DAMPER DEVICE

BACKGROUND

The disclosure according to the present disclosure relates to a damper device that includes an input element and an output element.

Hitherto, there has been known, as a damper device that is applicable to a starting device, a double-path damper used in association with a torque converter (see Published Japanese Translation of PCT Application No. 2012-506006, for example). In the damper device, a vibration path from an engine and a lock-up clutch (32) to an output hub (37) is divided into two parallel vibration paths B and C, and the two vibration paths B and C each have a pair of springs and a separate intermediate flange (36, 38) disposed between the pair of springs. In addition, a turbine (34) of the torque converter is coupled to the intermediate flange (36) of the vibration path B in order to make the natural frequencies of the two vibration paths different from each other, and the natural frequency of the intermediate flange (36) of the vibration path B is lower than the natural frequency of the intermediate flange (38) of the vibration path C. In such a damper device, in the case where the lock-up clutch (32) is engaged, vibration from the engine is input to the two vibration paths B and C of the damper device. When engine vibration at a certain frequency reaches the vibration path B which includes the intermediate flange (36) coupled to the turbine (34), the phase of vibration between the intermediate flange (36) of the vibration path B and the output hub (37) is shifted by 180 degrees with respect to the phase of input vibration. In this event, since the natural frequency of the intermediate flange (38) of the vibration path C is higher than the natural frequency of the intermediate flange (36) of the vibration path B, vibration which is input to the vibration path C is transferred to the output hub (37) without causing a shift (deviation) of the phase. In this way, vibration of the output hub (37) can be damped by shifting the phase of vibration transferred from the vibration path B to the output hub (37) and the phase of vibration transferred from the vibration path C to the output hub (37) by 180 degrees.

SUMMARY

In order to improve the vibration damping performance of the double-path damper described in Published Japanese Translation of PCT Application No. 2012-506006 mentioned above, it is necessary to appropriately set the natural frequencies of the vibration paths B and C by adjusting the spring constants of elastic bodies on both sides of the intermediate flanges and the weights of the intermediate flanges. If an attempt is made to make the natural frequencies of the vibration paths B and C appropriate by adjusting the spring constants of the elastic bodies, however, the rigidity of the entire double-path damper may be fluctuated significantly. If an attempt is made to make the two natural frequencies appropriate by adjusting the weights of the intermediate flanges and the turbine which is connected thereto, meanwhile, the weights of the flanges and the turbine, and hence the weight of the entire torque converter, may be increased. Thus, in the double-path damper described above, it is not easy to appropriately set the natural frequencies of the vibration paths B and C such that the vibration damping performance is improved, and vibration may not be damped well even by the damper device described in Published Japanese Translation of PCT Application No. 2012-506006 depending on the frequency of vibration to be damped.

An exemplary aspect of the present disclosure provides a damper device which is capable of setting the natural frequency easily and appropriately and the durability of which can be improved while suppressing an increase in size of the entire device.

The present disclosure provides a damper device that includes an input element to which torque from an engine is transferred; an output element; a first intermediate element; a second intermediate element; a first elastic body that transfers torque between the input element and the first intermediate element; a second elastic body that transfers torque between the first intermediate element and the output element; a third elastic body that transfers torque between the input element and the second intermediate element; a fourth elastic body that transfers torque between the second intermediate element and the output element; and a fifth elastic body that transfers torque between the first intermediate element and the second intermediate element. In the damper device, the third and fourth elastic bodies are disposed on a radially inner side with respect to the first and second elastic bodies; and the input element includes a first input member that has a first abutment portion abutting against an end portion of the first elastic body in a circumferential direction and that is rotatably supported by a first support portion, and a second input member that rotates together with the first input member, that has a second abutment portion abutting against an end portion of the third elastic body in the circumferential direction on the radially inner side with respect to the first abutment portion, and that is rotatably supported by a second support portion provided at a different position from that of the first support portion.

In the damper device, two natural frequencies can be set for the entire device when deflection of all of the first to fifth elastic bodies is allowed. The studies and the analyses conducted by the inventors revealed that the natural frequency of the damper device which included the first to fifth elastic bodies became lower as the rigidity of the fifth elastic body was lowered, and that variations in equivalent rigidity of the damper device with respect to variations in rigidity of the fifth elastic body were significantly small compared to variations in equivalent rigidity of the damper device with respect to variations in rigidities of the first to fourth elastic bodies. Thus, by adjusting the rigidity of the fifth elastic body, it is possible to set the two natural frequencies of the entire damper device easily and appropriately while keeping the equivalent rigidity of the device appropriate and suppressing an increase in weights (moments of inertia) of the first and second intermediate elements. In the damper device, in addition, a load from the input element, which abuts against both the first and second elastic bodies, can be distributed to the first and second support portions. Thus, the durability of the damper device can be improved while suppressing an increase in size of the support portions for the input element and hence the entire device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a starting device that includes a damper device according to the present disclosure.

FIG. 2 is a sectional view illustrating the starting device of FIG. 1.

FIG. 3 is a front view illustrating the constituent elements of the damper device according to the present disclosure.

FIG. 4 is a diagram illustrating the average attachment radii of first to fourth elastic bodies in the damper device according to the present disclosure.

FIG. 5 is a perspective view illustrating the constituent elements of the damper device according to the present disclosure.

FIG. 6 is a perspective view illustrating the constituent elements of the damper device according to the present disclosure.

FIG. 7 is a diagram illustrating torque transfer paths in the damper device according to the present disclosure.

FIG. 8 illustrates an example of the relationship between the rotational speed of an engine and theoretical torque fluctuations of output elements of damper devices.

FIG. 9 illustrates an example of the relationship between the rigidity of the first elastic body in the damper device according to the present disclosure and the natural frequency on the low-rotation side, the frequency of the antiresonance point, and the equivalent rigidity of the damper device.

FIG. 10 illustrates an example of the relationship between the rigidity of the second elastic body in the damper device according to the present disclosure and the natural frequency on the low-rotation side, the frequency of the antiresonance point, and the equivalent rigidity of the damper device.

FIG. 11 illustrates an example of the relationship between the rigidity of the third elastic body in the damper device according to the present disclosure and the natural frequency on the low-rotation side, the frequency of the antiresonance point, and the equivalent rigidity of the damper device.

FIG. 12 illustrates an example of the relationship between the rigidity of the fourth elastic body in the damper device according to the present disclosure and the natural frequency on the low-rotation side, the frequency of the antiresonance point, and the equivalent rigidity of the damper device.

FIG. 13 illustrates an example of the relationship between the rigidity of a fifth elastic body in the damper device according to the present disclosure and the natural frequency on the low-rotation side, the frequency of the antiresonance point, and the equivalent rigidity of the damper device.

FIG. 14 illustrates an example of the relationship between the moment of inertia of a first intermediate element in the damper device according to the present disclosure and the natural frequency on the low-rotation side, the frequency of the antiresonance point, and the equivalent rigidity of the damper device.

FIG. 15 illustrates an example of the relationship between the rotational speed of the engine and a phase difference Δλ between vibration transferred from the second elastic body to the output element and vibration transferred from the fourth elastic body to the output element.

FIG. 16 illustrates the relationship between the torque distribution ratios of the elastic bodies in the damper device according to the present disclosure and the vibration damping performances.

FIG. 17 illustrates an example of the relationship between the rotational speed of the engine and torque fluctuations of the output element of the damper device with a hysteresis taken into consideration.

DETAILED DESCRIPTION OF EMBODIMENTS

Now, an embodiment of the disclosure according to the present disclosure will be described with reference to the drawings.

FIG. 1 is a schematic diagram illustrating a starting device 1 that includes a damper device 10 according to the present disclosure. FIG. 2 is a sectional view illustrating the starting device 1. The starting device 1 illustrated in the drawings is mounted on a vehicle that includes an engine (in the present embodiment, an internal combustion engine) EG that serves as a motor. In addition to the damper device 10, the starting device 1 includes: a front cover 3 coupled to a crankshaft of the engine EG; a pump impeller (input-side fluid transmission element) 4 fixed to the front cover 3; a turbine runner (output-side fluid transmission element) 5 that is coaxially rotatable with the pump impeller 4; a damper hub 7 that serves as a power output member coupled to the damper device 10 and fixed to an input shaft IS of a transmission (power transfer device) TM that is an automatic transmission (AT), a continuously variable transmission (CVT), a dual clutch transmission (DCT), a hybrid transmission, or a speed reducer; a lock-up clutch 8; and so forth.

In the following description, unless specifically stated, the term “axial direction” basically indicates the direction of extension of a center axis CA (axis; see FIG. 4) of the starting device 1 and the damper device 10. In addition, unless specifically stated, the term “radial direction” basically indicates the radial direction of a rotational element such as the starting device 1 or the damper device 10, that is, the direction of extension of a line that extends in directions (radial directions) that are orthogonal to the center axis CA from the center axis CA of the starting device 1 or the damper device 10. Furthermore, unless specifically stated, the term “circumferential direction” basically indicates the circumferential direction of a rotary element such as the starting device 1 or the damper device 10, that is, the direction along the rotational direction of such a rotary element.

As illustrated in FIG. 2, the pump impeller 4 has a pump shell 40 tightly fixed to the front cover 3 and a plurality of pump blades 41 disposed on the inner surface of the pump shell 40. As illustrated in FIG. 2, the turbine runner 5 has a turbine shell 50 and a plurality of turbine blades 51 disposed on the inner surface of the turbine shell 50. The inner peripheral portion of the turbine shell 50 is fixed to a turbine hub 52 via a plurality of rivets. The turbine hub 52 is rotatably supported by the damper hub 7. Movement of the turbine hub 52 (turbine runner 5) in the axial direction of the starting device 1 is restricted by the damper hub 7 and a snap ring mounted to the damper hub 7.

The pump impeller 4 and the turbine runner 5 face each other. A stator 6 is disposed between and coaxially with the pump impeller 4 and the turbine runner 5. The stator 6 adjusts a flow of working oil (working fluid) from the turbine runner 5 to the pump impeller 4. The stator 6 has a plurality of stator blades 60. The rotational direction of the stator 6 is set to only one direction by a one-way clutch 61. The pump impeller 4, the turbine runner 5, and the stator 6 form a torus (annular flow passage) that allows circulation of working oil, and function as a torque converter (fluid transmission apparatus) with a torque amplification function. It should be noted, however, that the stator 6 and the one-way clutch 61 may be omitted from the starting device 1, and that the pump impeller 4 and the turbine runner 5 may function as a fluid coupling.

The lock-up clutch 8 can establish and release lock-up in which the front cover 3 and the damper hub 7 are coupled to each other via the damper device 10. In the present embodiment, the lock-up clutch 8 is constituted as a hydraulic single-plate clutch, and has a lock-up piston (power input member) 80 disposed inside the front cover 3 and in the vicinity of the inner wall surface of the front cover 3 on the engine EG side and fitted so as to be movable in the axial direction with respect to the damper hub 7. In addition, as illustrated in FIG. 2, a friction material 88 is affixed to a surface of the lock-up piston 80 on the outer peripheral side and on the front cover 3 side. Furthermore, a lock-up chamber (engagement oil chamber) 85 is defined between the lock-up piston 80 and the front cover 3. The lock-up chamber 85 is connected to a hydraulic control device (not illustrated) via a working oil supply passage and an oil passage formed in the input shaft IS.

Working oil from the hydraulic control device, which is supplied radially outward from a portion near the axis of the pump impeller 4 and the turbine runner 5 (the vicinity of the one-way clutch 61) to the pump impeller 4 and the turbine runner 5 (torus) via the oil passage which is formed in the input shaft IS, can flow into the lock-up chamber 85. Thus, if the pressure in a fluid transmission chamber 9 defined by the front cover 3 and the pump shell of the pump impeller 4 and the pressure in the lock-up chamber 85 are kept equal to each other, the lock-up piston 80 is not moved toward the front cover 3, and the lock-up piston 80 is not frictionally engaged with the front cover 3. If the hydraulic pressure in the fluid transmission chamber 9 is made higher than the hydraulic pressure in the lock-up chamber 89 by the hydraulic control device (not illustrated), in contrast, the lock-up piston 80 is moved toward the front cover 3 by a pressure difference to be frictionally engaged with the front cover 3. Consequently, the front cover 3 (engine EG) is coupled to the damper hub 7 via the lock-up piston 80 and the damper device 10. A hydraulic multi-plate clutch that includes at least one friction engagement plate (a plurality of friction materials) may be adopted as the lock-up clutch 8. In this case, a clutch drum or a clutch hub of the hydraulic multi-plate clutch functions as the power input member.

The damper device 10 damps vibration between the engine EG and the transmission TM. As illustrated in FIG. 1, the damper device 10 includes, as rotary elements (rotary members, i.e. rotary mass bodies) that rotate coaxially relative to each other, a drive member (input element) 11, a first intermediate member (first intermediate element) 12, a second intermediate member (second intermediate element) 14, and a driven member (output element) 16. The damper device 10 further includes, as torque transfer elements (torque transfer elastic bodies): a plurality of (e.g. two in the present embodiment) first outer springs (first elastic bodies) SP11 disposed between the drive member 11 and the first intermediate member 12 to transfer rotational torque (torque in the rotational direction); a plurality of (e.g. two in the present embodiment) second outer springs (second elastic bodies) SP12 disposed between the first intermediate member 12 and the driven member 16 to transfer rotational torque; a plurality of (e.g. three in the present embodiment) first inner springs (third elastic bodies) SP21 disposed between the drive member 11 and the second intermediate member 14 to transfer rotational torque; a plurality of (e.g. three in the present embodiment) second inner springs (fourth elastic bodies) SP22 disposed between the second intermediate member 14 and the driven member 16 to transfer rotational torque; and a plurality of (e.g. two in the present embodiment) intermediate springs (fifth elastic bodies) SPm disposed between the first intermediate member 12 and the second intermediate member 14 to transfer rotational torque.

In the present embodiment, linear coil springs made of a metal material spirally wound so as to have an axis that extends straight when no load is applied are adopted as the first and second outer springs SP11 and SP12, the first and second inner springs SP21 and SP22, and the intermediate springs SPm. Consequently, a hysteresis due to a friction force generated between the springs which transfer torque and the rotary elements, that is, the difference between torque output when torque input to the drive member 11 is increasing and torque output when torque input to the drive member 11 is decreasing, can be reduced by expanding and contracting the springs SP11 to SPm along the axes more appropriately than the case where are coil springs are used. The hysteresis may be quantified by the difference between torque output from the driven member 16 when the torsional angle of the damper device 10 is brought to a predetermined angle with torque input to the drive member 11 increasing and torque output from the driven member 16 when the torsional angle of the damper device 10 is brought to the predetermined angle described above with torque input to the drive member 11 decreasing. At least one of the springs SP11 to SPm may be an arc coil spring. The term “axis of a spring” means the center of winding of a metal material wound spirally in a linear coil spring or an arc coil spring.

In the present embodiment, in addition, as illustrated in FIG. 3, the first outer springs SP11, the second outer springs SP12, and the intermediate springs SPm are arranged side by side in the order of SP11, SP12, SPm, SP11, SP12, and SPm, for example, along the circumferential direction of the damper device 10 (first intermediate member 12), and disposed in the outer peripheral region in the fluid transmission chamber 9 in proximity to the outer periphery of the starting device 1. In this way, by disposing the intermediate springs SPm side by side with the first and second outer springs SP11 and SP12 on the outer peripheral side along the circumferential direction, it is possible to secure the torsional angle (stroke) between the first and second outer springs SP11 and SP12 and the intermediate springs SPm well. In contrast, as illustrated in FIG. 3, the first and second inner springs SP21 and SP22 are disposed on the radially inner side of the first and second outer springs SP11 and SP12 and the intermediate springs SPm such that one first inner spring SP21 and one second inner spring SP22 are paired (act in series with each other), and such that the first and second inner springs SP21 and SP22 are arranged alternately along the circumferential direction of the damper device 10 (second intermediate member 14), and surrounded by the springs SP11, SP12, and SPm.

Consequently, in the damper device 10, an average attachment radius ro of the first and second outer springs SP11 and SP12 is larger than an average attachment radius ri of the first and second inner springs SP21 and SP22. As illustrated in FIG. 4, the average attachment radius ro of the first and second outer springs SP11 and SP12 is the average value (=(r_SP11+r_SP12)/2) of an attachment radius r_SP11of the first outer springs SP11, which is the distance from the center axis CA of the damper device 10 to the axis of the first outer springs (first elastic bodies) SP11, and an attachment radius r_SP12of the second outer springs SP12, which is the distance from the center axis CA to the axis of the second outer springs (second elastic bodies) SP12. As illustrated in FIG. 4, the average attachment radius ri of the first and second inner springs SP21 and SP22 is the average value (=(r_SP21+r_SP22)/2) of an attachment radius r_SP21of the first inner springs SP21, which is the distance from the center axis CA to the axis of the first inner springs (third elastic bodies) SP21, and an attachment radius r_SP22of the second inner springs SP22, which is the distance from the center axis CA to the axis of the second inner springs (fourth elastic bodies) SP22. The attachment radius r_SP11, r_SP12, r_SP21, or r_SP22may be the distance between the center axis CA and a point (e.g. the center or an end portion in the axial direction) determined in advance on the axis of the springs SP11, SP12, SP21, or SP22.

In the present embodiment, in addition, the first and second outer springs SP11 and SP12 (and the intermediate springs SPm) are arranged on the same circumference so that the attachment radius r_SP11and the attachment radius r_SP12are equal to each other, and the axis of the first outer springs SP11 and the axis of the second outer springs SP12 are included in one plane that is orthogonal to the center axis CA. In the present embodiment, further, the first and second inner springs SP21 and SP22 are arranged on the same circumference so that the attachment radius r_SP21and the attachment radius r_SP22are equal to each other, and the axis of the first inner springs SP21 and the axis of the second inner springs SP22 are included in one plane that is orthogonal to the center axis CA. In the damper device 10, additionally, the first and second inner springs SP21 and SP22 are disposed on the radially inner side of the first and second outer springs SP11 and SP12 so as to overlap the first and second outer springs SP11 and SP12 in the axial direction as seen in the radial direction. Consequently, it is possible to make the damper device 10 compact in the radial direction, and to shorten the axial length of the damper device 10.

It should be noted, however, that as illustrated in FIG. 4, the attachment radius r_SP11from the center axis CA to the axis of the first outer springs SP11 and the attachment radius r_SP12from the center axis CA to the axis of the second outer springs SP12 may be different from each other. In addition, the attachment radius r_SP21from the center axis CA to the axis of the first inner springs SP21 and the attachment radius r_SP22from the center axis CA to the axis of the second inner springs SP22 may be different from each other. That is, the attachment radius r_SP11, r_SP12of at least one of the first and second outer springs SP11 and SP12 may be larger than the attachment radius r_SP21, r_SP22of at least one of the first and second inner springs SP21 and SP22. Furthermore, the axis of the first outer springs SP11 and the axis of the second outer springs SP12 may not be included in one plane that is orthogonal to the center axis CA. In addition, the axis of the first inner springs SP21 and the axis of the second inner springs SP22 may not be included in one plane that is orthogonal to the center axis CA. In addition, the axes of the springs SP11, SP12, SP21, and SP22 may be included in one plane that is orthogonal to the center axis CA, and at least one of the axes of the springs SP11, SP12, SP21, and SP22 may not be included in the one plane.

In the present embodiment, the rigidity, that is, the spring constant, of the first outer springs SP11 is defined as “k₁₁”, the rigidity, that is, the spring constant, of the second outer springs SP12 is defined as “k₁₂”, the rigidity, that is, the spring constant, of the first inner springs SP21 is defined as “k₂₁”, and the rigidity, that is, the spring constant, of the second inner springs SP22 is defined as “k₂₂”. The spring constants k₁₁, k₁₂, k₂₁, and k₂₂are selected such that the relations k₁₁≠k₂₁and k₁₁/k₂₁≠k₁₂/k₂₂are met. More particularly, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂meet the relations k₁₁/k₂₁<k₁₂/k₂₂and k₁₁<k₁₂<k₂₂<k₂₁. That is, the smaller one (k₁₁) of the spring constants k₁₁and k₁₂of the first and second outer springs SP11 and SP12 is smaller than the smaller one (k₂₂) of the spring constants k₂₁and k₂₂of the first and second inner springs SP21 and SP22. When the rigidity, that is, the spring constant, of the intermediate springs SPm is defined as “k_m”, further, the spring constants k₁₁, k₁₂, k₂₁, k₂₂, and k_mmeet the relation k₁₁<k_m<k₁₂<k₂₂<k₂₁.

As illustrated in FIG. 2, the drive member 11 of the damper device 10 includes: an annular first plate member (first input member) 111 fixed to the lock-up piston 80 of the lock-up clutch 8; an annular second plate member (second input member) 112 rotatably supported (aligned) by the damper hub 7 and coupled so as to be rotatable together with the first plate member 111; and an annular third plate member (third input member) 113 disposed in more proximity to the turbine runner 5 than the second plate member 112 and coupled (fixed) to the second plate member 112 via a plurality of rivets (couplers) 125. Consequently, the drive member 11, that is, the first, second, and third plate members 111, 112, and 113, rotates together with the lock-up piston 80, and the front cover 3 (engine EG) and the drive member 11 of the damper device 10 are coupled to each other through engagement of the lock-up clutch 8.

As illustrated in FIGS. 2 and 5, the first plate member 111 has: an annular fixed portion 111a fixed to the inner surface (a surface to which the friction material 88 is not affixed) of the lock-up piston 80 on the outer peripheral side via a plurality of rivets; a short tubular portion 111b that extends in the axial direction from the outer peripheral portion of the fixed portion 111a; a plurality of (e.g. four in the present embodiment) spring abutment portions (first abutment portions) 111c that extend radially outward at intervals (equal intervals) in the circumferential direction from the free end portion of the tubular portion 111b and that extend in the axial direction away from the fixed portion 111a; and a plurality of (e.g. twelve in the present embodiment) engagement projecting portions 111e that extend in the axial direction from the free end portion of the tubular portion 111b at intervals in the circumferential direction. As illustrated in FIG. 2, the lock-up piston 80 to which the first plate member 111 is fixed is rotatably supported by a cylindrical first support portion 71 formed on the damper hub 7.

The second plate member 112 is constituted as an annular plate-like member, disposed in more proximity to the lock-up piston 80 than the third plate member 113, and rotatably supported by a cylindrical second support portion 72 formed on the damper hub 7. As illustrated in FIG. 2, the second support portion 72 of the damper hub 7 is formed as shifted in the axial direction of the damper device 10 from the first support portion 71 so as to be in more proximity to the turbine runner 5 than the first support portion 71. In addition, the second support portion 72 has an outside radius that is larger than that of the first support portion 71, and is provided on the radially outer side of the first support portion 71.

In addition, the second plate member 112 has: a plurality of (e.g. three in the present embodiment) spring housing windows 112w (see FIGS. 3 and 5) that extend arcuately and that are disposed at intervals (at equal intervals) in the circumferential direction; a plurality of (e.g. three in the present embodiment) spring support portions 112a that extend along the inner peripheral edges of the respective spring housing windows 112w and that are arranged at intervals (equal intervals) in the circumferential direction; a plurality of (e.g. three in the present embodiment) spring support portions 112b that extend along the outer peripheral edges of the respective spring housing windows 112w and that are arranged at intervals (equal intervals) in the circumferential direction to face the respective spring support portions 112a in the radial direction of the second plate member 112; and a plurality of (e.g. three in the present embodiment) spring abutment portions (second abutment portions) 112c. The plurality of spring abutment portions 112c of the second plate member 112 are provided such that each spring abutment portion 112c is interposed between the spring housing windows 112w (spring support portions 112a and 112b) which are adjacent to each other along the circumferential direction. Furthermore, a plurality of (e.g. twelve in the present embodiment) engagement recessed portions 112e are formed at the outer peripheral portion of the second plate member 112 at intervals in the circumferential direction. The engagement recessed portions 112e are fitted with the respective engagement projecting portions 111e of the first plate member 111 with backlash in the radial direction. The first and second plate members 111 and 112 are relatively movable in the radial direction with the engagement projecting portions 111e fitted with the engagement recessed portions 112e.

The third plate member 113 is also constituted of an annular plate-like member. The third plate member 113 has: a plurality of (e.g. three in the present embodiment) spring housing windows that extend arcuately and that are disposed at intervals (at equal intervals) in the circumferential direction; a plurality of (e.g. three in the present embodiment) spring support portions 113a that extend along the inner peripheral edges of the respective spring housing windows and that are arranged at intervals (equal intervals) in the circumferential direction; a plurality of (e.g. three in the present embodiment) spring support portions 113b that extend along the outer peripheral edges of the respective spring housing windows and that are arranged at intervals (equal intervals) in the circumferential direction to face the respective spring support portions 113a in the radial direction of the third plate member 113; and a plurality of (e.g. three in the present embodiment) spring abutment portions (third abutment portions) 113c. The plurality of spring abutment portions 113c of the third plate member 113 are provided such that each spring abutment portion 113c is interposed between the spring support portions 113a and 113b (spring housing windows) which are adjacent to each other along the circumferential direction.

As illustrated in FIG. 2, the first intermediate member 12 includes an elastic body support member 121 and a coupling member 122. The elastic body support member 121 is formed in an annular shape so as to support (guide) the outer peripheral portions of the first and second outer springs SP11 and SP12, the side portions (right side portions in FIG. 2) of the first and second outer springs SP1 and SP12 on the lock-up piston 80 side (engine EG side), and the outer peripheral side of the side portions of the first and second outer springs SP11 and SP12 on the turbine runner 5 side (transmission TM side). The elastic body support member 121 is rotatably supported (aligned) in the radial direction by the tubular portion 111b of the first plate member 111 of the drive member 11, and disposed in the outer peripheral region in the fluid transmission chamber 9. By disposing the first intermediate member 12 in the outer peripheral region in the fluid transmission chamber 9 in this way, it is possible to make the moment of inertia (inertia) of the first intermediate member 12 larger. In addition, the elastic body support member 121 has a plurality of (e.g. two at intervals of 180° in the present embodiment) spring abutment portions 121c disposed at intervals in the circumferential direction. The spring abutment portions 121c extend in the axial direction from the side portion of the elastic body support member 121 on the lock-up piston 80 side toward the turbine runner 5.

The coupling member 122 which constitutes the first intermediate member 12 has: an annular fixed portion (annular portion) 122a fixed to the turbine shell 50 of the turbine runner 5 by welding, for example; a plurality of (e.g. two at intervals of 180° in the present embodiment) spring abutment portions (first spring abutment portions) 122c that extend in the axial direction from the outer peripheral portion of the fixed portion 122a at intervals in the circumferential direction; a plurality of (e.g. four in the present embodiment) second spring abutment portions 122d that extend in the axial direction from the outer peripheral portion of the fixed portion 122a between the spring abutment portions 122c; and a support portion 122s in a short cylindrical shape that extends in the axial direction from the inner peripheral portion of the fixed portion 122a toward the same side as the spring abutment portions 122c and 122d extend. The plurality of second spring abutment portions 122d of the coupling member 122 are formed symmetrically with respect to the axis of the coupling member 122 such that two (a pair of) second spring abutment portions 122d are proximate to each other (see FIG. 3). The two second spring abutment portions 122d which are paired with each other are arranged in the circumferential direction at an interval that matches the natural length of the intermediate springs SPm, for example.

The second intermediate member 14 has: an annular supported portion (annular portion) 14a; a plurality of (e.g. three at intervals of 120° in the present embodiment) spring abutment portions (first spring abutment portions) 14c that extend in the axial direction from the inner peripheral portion of the supported portion 14a at intervals in the circumferential direction; and a plurality of (e.g. four in the present embodiment) second spring abutment portions 14d that extend in the axial direction from the outer peripheral portion of the supported portion 14a toward the same side as the spring abutment portions 14c extend. The plurality of second spring abutment portions 14d of the second intermediate member 14 are formed symmetrically with respect to the axis of the second intermediate member 14 such that two (a pair of) second spring abutment portions 14d are proximate to each other (see FIG. 3). The two second spring abutment portions 14d which are paired with each other are arranged in the circumferential direction at an interval that matches the natural length of the intermediate springs SPm, for example.

As illustrated in FIG. 2, the second intermediate member 14 is rotatably supported by the coupling member 122 of the first intermediate member 12 which is fixed to the turbine runner 5, and the supported portion 14a of the second intermediate member 14 is positioned between the third plate member 113 of the drive member 11 and the turbine runner 5 in the axial direction. In the present embodiment, the supported portion 14a of the second intermediate member 14 is formed with a recessed portion with which the support portion 122s of the coupling member 122 is fitted, and the second intermediate member 14 is rotatably supported by the support portion 122s. In addition, movement of the second intermediate member 14 toward the turbine runner 5 is restricted with the supported portion 14a of the second intermediate member 14 abutting against the distal end of the support portion 122s. Furthermore, a plurality of movement restriction projecting portions 113s are formed at the outer peripheral portion of the third plate member 113 at intervals in the circumferential direction. The plurality of movement restriction projecting portions 113s project from the surface on the turbine runner 5 side toward the second intermediate member 14. Thus, movement of the second intermediate member 14 in the direction away from the turbine runner 5 (toward the lock-up piston 80) is restricted with the supported portion 14a of the second intermediate member 14 abutting against the movement restriction projecting portions 113s of the third plate member 113.

The driven member 16 is constituted as an annular plate-like member. As illustrated in FIG. 2, the driven member 16 is disposed between the second plate member 112 and the third plate member 113 of the drive member 11 in the axial direction, and fixed to the damper hub 7 (in the present embodiment, the second support portion 72) via rivets. Consequently, the driven member 16 is rotated together with the damper hub 7. The driven member 16 has: a plurality of (e.g. three in the present embodiment) spring housing windows that extend arcuately and that are disposed at intervals (equal intervals) in the circumferential direction; a plurality of (e.g. three in the present embodiment) inner spring abutment portions (inner abutment portions) 16ci formed at intervals in the circumferential direction in proximity to the inner peripheral edge of the driven member 16; and a plurality of (e.g. four in the present embodiment) outer spring abutment portions (outer abutment portions) 16co that are arranged at intervals (equal intervals) in the circumferential direction on the radially outer side with respect to the plurality of inner spring abutment portions 16ci and that extend in the axial direction from the turbine runner 5 side toward the lock-up piston 80. The plurality of inner spring abutment portions 16ci of the driven member 16 are provided such that each inner spring abutment portion 16ci is interposed between the spring housing windows which are adjacent to each other along the circumferential direction.

As illustrated in FIG. 2, the first and second outer springs SP11 and SP12 are supported by the elastic body support member 121 of the first intermediate member 12 such that one first outer spring SP11 and one second outer spring SP12 are paired (act in series with each other), and such that the first and second outer springs SP11 and SP12 are arranged alternately along the circumferential direction of the first intermediate member 12. In addition, with the damper device 10 in an attached state, the spring abutment portions 111c of the first plate member 111 of the drive member 11 each abut against the end portion (end portion in the deflection direction; the same applies hereinafter) of a corresponding one of first and second outer springs SP11 and SP12 in the circumferential direction. Furthermore, as illustrated in FIG. 3, the spring abutment portions 121c of the elastic body support member 121 are each provided between the first and second outer springs SP11 and SP12, which are adjacent to and pared with each other (act in series with each other), so as to abut against the end portions of such first and second outer springs SP11 and SP12 in the circumferential direction. In addition, as illustrated in FIG. 3, the spring abutment portions 122c of the coupling member 122 are each also provided between the first and second outer springs SP11 and SP12, which are adjacent to and paired with each other, so as to abut against the end portions of such first and second outer springs SP11 and SP12 in the circumferential direction.

That is, with the damper device 10 in the attached state, a first end portion (end portion on the intermediate spring SPm side in FIG. 3) of each first outer spring SP11 abuts against a corresponding one of the spring abutment portions 111c of the drive member 11, and a second end portion (end portion on the second outer spring SP12 side in FIG. 3) of each first outer spring SP11 abuts against a corresponding one of the spring abutment portions 121c and a corresponding one of the spring abutment portions 122c of the first intermediate member 12. With the damper device 10 in the attached state, in addition, a first end portion (end portion on the first outer spring SP11 side in FIG. 3) of each second outer spring SP12 abuts against a corresponding one of the spring abutment portions 121c and a corresponding one of the spring abutment portions 122c of the first intermediate member 12, and a second end portion (end portion on the intermediate spring SPm side in FIG. 3) of each second outer spring SP12 abuts against a corresponding one of the spring abutment portions 111c of the drive member 11.

Furthermore, as with the spring abutment portions 111c of the drive member 11, the outer spring abutment portions 16co of the driven member 16 are each provided between the first and second outer springs SP11 and SP12, which are not paired (do not act in series with each other), so as to abut against the end portions of such first and second outer springs SP11 and SP12 in the circumferential direction. That is, with the damper device 10 in the attached state, the first end portion (end portion on the intermediate spring SPm side) of the first outer spring SP11 and the second end portion (end portion on the intermediate spring SPm side) of the second outer spring SP12 which is paired with the first outer spring SP11 abut against the respective outer spring abutment portions 16co of the driven member 16. As a result, the driven member 16 is coupled to the drive member 11 via the plurality of first outer springs SP11, the first intermediate member 12 (the elastic body support member 121 and the coupling member 122), and the plurality of second outer springs SP12.

In addition, the coupling member 122 of the first intermediate member 12 is fixed to the turbine runner 5. Thus, the first intermediate member 12 and the turbine runner 5 are coupled so as to rotate together with each other. In this way, by coupling the turbine runner 5 (and the turbine hub 52) to the first intermediate member 12, it is possible to further increase the substantial moment of inertia of the first intermediate member 12 (the total of the moments of inertia of the elastic body support member 121, the coupling member 122, the turbine runner 5, and so forth). In addition, by coupling the turbine runner 5 and the first intermediate member 12, which is disposed on the radially outer side of the first and second inner springs SP21 and SP22, that is, in the outer peripheral region in the fluid transmission chamber 9, to each other, it is possible to prevent the coupling member 122 from passing through a space between the third plate member 113 of the drive member 11 or the first and second inner springs SP21 and SP22 and the turbine runner 5 in the axial direction. Consequently, it is possible to suppress an increase in axial length of the damper device 10, and hence the starting device 1, better.

Meanwhile, as illustrated in FIGS. 2 and 3, the plurality of spring support portions 112a of the second plate member 112 support (guide) the side portions of the associated first and second inner springs SP21 and SP22 (one each) on the lock-up piston 80 side from the inner peripheral side. In addition, the plurality of spring support portions 112b support (guide) the side portions of the associated first and second inner springs SP21 and SP22 on the lock-up piston 80 side from the outer peripheral side. Furthermore, as illustrated in FIG. 2, the plurality of spring support portions 113a of the third plate member 113 support (guide) the side portions of the associated first and second inner springs SP21 and SP22 (one each) on the turbine runner 5 side from the inner peripheral side. In addition, the plurality of spring support portions 113b support (guide) the side portions of the associated first and second inner springs SP21 and SP22 on the turbine runner 5 side from the outer peripheral side. That is, the first and second inner springs SP21 and SP22 are supported by the spring support portions 112a and 112b of the second plate member 112 and the spring support portions 113a and 113b of the third plate member 113, which constitute the drive member 11, such that one first inner spring SP21 and one second inner spring SP22 are paired (act in series with each other) and such that the first and second inner springs SP21 and SP22 are arranged alternately in the circumferential direction (circumferential direction of the second intermediate member 14).

Furthermore, as illustrated in FIG. 3, with the damper device 10 in the attached state, the spring abutment portions 112c of the second plate member 112 are each provided between the first and second inner springs SP21 and SP22, which are supported by different spring housing windows 112w (spring support portions 112a, 112b, 113a, and 113b) and which are not paired (do not act in series with each other), so as to abut against the end portions of such first and second inner springs SP21 and SP22 in the circumferential direction. Similarly, with the damper device 10 in the attached state, the spring abutment portions 113c of the third plate member 113 are each provided between the first and second inner springs SP21 and SP22, which are supported by different spring support portions 112a, 112b, 113a, and 113b (spring housing windows) (which are not paired), so as to abut against the end portions of such first and second inner springs SP21 and SP22 in the circumferential direction. In addition, as illustrated in FIG. 3, the spring abutment portions 14c of the second intermediate member 14 are each provided between the first and second inner springs SP21 and SP22, which are paired with each other (act in series with each other), so as to abut against the end portions of such first and second inner springs SP21 and SP22 in the circumferential direction.

That is, with the damper device 10 in the attached state, a first end portion of each first inner spring SP21 abuts against a corresponding one of the spring abutment portions 112c and a corresponding one of the spring abutment portions 113c of the drive member 11, and a second end portion of each first inner spring SP21 abuts against a corresponding one of the spring abutment portions 14c of the second intermediate member 14. Furthermore, with the damper device 10 in the attached state, a first end portion of each second inner spring SP22 abuts against a corresponding spring abutment portions 14c of the second intermediate member 14, and a second end portion of each second inner spring SP22 abuts against a corresponding one of the spring abutment portions 112c and a corresponding one of the spring abutment portions 113c of the drive member 11. As illustrated in FIG. 3, spring seats Ss may be disposed between each spring abutment portion 14c and the second end portion of the corresponding first inner spring SP21 and between the spring abutment portion 14c and the first end portion of the corresponding second inner spring SP22.

In addition, with the damper device 10 in the attached state, as with the spring abutment portions 112c and 113c of the drive member 11, the inner spring abutment portions 16ci of the driven member 16 are each provided between the first and second inner springs SP21 and SP22, which are not paired (do not act in series with each other), so as to abut against the end portions of such first and second inner springs SP21 and SP22 in the circumferential direction. Consequently, with the damper device 10 in the attached state, the first end portion of each first inner spring SP21 also abuts against the corresponding inner spring abutment portion 16ci of the driven member 16, and the second end portion of each second inner spring SP22 also abuts against the corresponding inner spring abutment portion 16ci of the driven member 16. As a result, the driven member 16 is coupled to the drive member 11 via the plurality of first inner springs SP21, the second intermediate member 14, and the plurality of second inner springs SP22.

With the damper device 10 in the attached state, each intermediate spring SPm is supported from both sides by the pair of second spring abutment portions 122d of the first intermediate member 12 (coupling member 122), and supported from both sides by the pair of second spring abutment portions 14d of the second intermediate member 14. Consequently, the first intermediate member 12 and the second intermediate member 14 are coupled to each other via the plurality of intermediate springs SPm. In the present embodiment, as illustrated in FIGS. 1 and 6, spring seats Ss are disposed between the end portions of the intermediate springs SPm and the second spring abutment portions 14d and 122d.

Furthermore, as illustrated in FIG. 1, the damper device 10 includes: a first stopper 21 that restricts relative rotation between the first intermediate member 12 and the driven member 16 and deflection of the second outer springs SP12; a second stopper 22 that restricts relative rotation between the second intermediate member 14 and the driven member 16 and deflection of the second inner springs SP22; and a third stopper 23 that restricts relative rotation between the drive member 11 and the driven member 16. The first and second stoppers 21 and 22 are configured to restrict relative rotation between the associated rotary elements and deflection of the springs generally at the same time as input torque transferred from the engine EG to the drive member 11 has reached torque (a first threshold) T1 that is determined in advance and that is less than torque T2 (a second threshold) corresponding to a maximum torsional angle θmax of the damper device 10. In addition, the third stopper 23 is configured to restrict relative rotation between the drive member 11 and the driven member 16 when torque input to the drive member 11 has reached the torque T2 corresponding to the maximum torsional angle θmax. Consequently, the damper device 10 has damping characteristics in two stages.

In the present embodiment, as illustrated in FIG. 2, the first stopper 21 is constituted from: a plurality of stopper portions 122x that extend in the axial direction from the coupling member 122, which constitutes the first intermediate member 12, toward the lock-up piston 80 at intervals in the circumferential direction; and a plurality of notch portions 161x formed in the outer peripheral portion of the driven member 16 at intervals in the circumferential direction to extend arcuately. With the damper device 10 in the attached state, the stopper portions 122x of the first intermediate member 12 (coupling member 122) are inserted through any of a plurality of arcuate slits 14v formed in the outer peripheral portion of the supported portion 14a of the second intermediate member 14 at intervals in the circumferential direction, and disposed in the respective notch portions 161x of the driven member 16 so as not to abut against the wall surfaces of the driven member 16 which define the end portions of the notch portions 161x on both sides. Consequently, when each stopper portion 122x of the coupling member 122 and one of the wall surfaces which define the end portions of the notch portion 161x on both sides abut against each other along with relative rotation between the first intermediate member 12 and the driven member 16, relative rotation between the first intermediate member 12 and the driven member 16 and deflection of the second outer springs SP12 are restricted. In the present embodiment, the stopper portions 122x of the first intermediate member 12 and the wall surfaces of the second intermediate member 14 which define the end portions of the slits 14v on both sides do not abut against each other during a period before relative rotation between the drive member 11 and the driven member 16 is restricted by the third stopper 23.

In the present embodiment, in addition, as illustrated in FIG. 2, the second stopper 22 is constituted from: a plurality of slits 14x formed in the inner peripheral portion of the supported portion 14a of the second intermediate member 14 at intervals in the circumferential direction to extend arcuately; and a plurality of stopper portions 162x that extend in the axial direction from the driven member 16 toward the turbine runner 5 at intervals in the circumferential direction. With the damper device 10 in the attached state, the stopper portions 162x of the driven member 16 are inserted through any of a plurality of arcuate slits 113v formed in the outer peripheral portion of the third plate member 113 of the drive member 11 at intervals in the circumferential direction, and disposed in the respective slits 14x of the second intermediate member 14 so as not to abut against the wall surfaces of the second intermediate member 14 which define the end portions of the slits 14x on both sides. Consequently, when each stopper portion 162x of the driven member 16 and one of the wall surfaces of the second intermediate member 14 which define the end portions of the slits 14x on both sides abut against each other along with relative rotation between the second intermediate member 14 and the driven member 16, relative rotation between the second intermediate member 14 and the driven member 16 and deflection of the second inner springs SP22 are restricted. In the present embodiment, the stopper portions 162x of the driven member 16 and the wall surfaces of the third plate member 113 which define the end portions of the slits 113v on both sides do not abut against each other during a period before relative rotation between the drive member 11 and the driven member 16 is restricted by the third stopper 23.

In the present embodiment, further, as illustrated in FIG. 2, the third stopper 23 is constituted from: collars mounted to the plurality of rivets which couple the second and third plate members 112 and 113, which constitute the drive member 11, to each other, and a plurality of notch portions 163x formed in the driven member 16 at intervals in the circumferential direction to extend arcuately. With the damper device 10 in the attached state, the plurality of rivets 125 and the collars are disposed in the respective notch portions 163x of the driven member 16 so as not to abut against the wall surfaces of the driven member 16 which define the end portions of the notch portions 163x on both sides. Consequently, when each collar discussed above and one of the wall surfaces which define the end portions of the notch portions 163x on both sides abut against each other along with relative rotation between the drive member 11 and the driven member 16, relative rotation between the drive member 11 and the driven member 16 is restricted.

In the damper device 10, as discussed above, the average attachment radius ro of the first and second outer springs SP11 and SP12 corresponding to the first intermediate member 12 is determined to be larger than the average attachment radius ri of the first and second inner springs SP21 and SP22. That is, the axis of the first and second outer springs SP11 and SP12 which have a spring constant (rigidity) that is smaller than that of the first and second inner springs SP21 and SP22 is positioned on the outer side, in the radial direction of the damper device 10, with respect to the axis of the first and second inner springs SP21 and SP22. In the damper device 10, in addition, the first and second outer springs SP11 and SP12 are disposed such that the entire first and second outer springs SP11 and SP12 are positioned on the radially outer side with respect to the first and second inner springs SP21 and SP22.

Consequently, it is possible to increase the moment of inertia of the first intermediate member 12, and to lower the rigidities of the first and second outer springs SP11 and SP12. In addition, in the case where the average attachment radius ro of the first and second outer springs SP11 and SP12 is larger than the average attachment radius ri of the first and second inner springs SP21 and SP22, the first and second outer springs SP11 and SP12, which are low in rigidity and relatively light in weight, are disposed on the outer peripheral side of the damper device 10, and the first and second inner springs SP21 and SP22, which are high in rigidity and relatively heavy in weight, are disposed on the center axis CA side of the damper device 10. Consequently, it is possible to reduce the hysteresis of the entire damper device 10 by reducing a friction force generated between the springs SP11, SP12, SP21, and SP22 and the associated rotary elements because of a centrifugal force.

In addition, by causing the elastic body support member 121 (first intermediate member 12) to support the first and second outer springs SP11 and SP12, it is possible to reduce the relative speed between the first and second outer springs SP11 and SP12, which are deflected in accordance with the torsional angle of the elastic body support member 121 with respect to the drive member 11 or the driven member 16, and the elastic body support member 121. Thus, a friction force generated between the elastic body support member 121 and the first and second outer springs SP1 and SP12 can be reduced. Thus, it is possible to lower the hysteresis of the entire damper device 10.

In the damper device 10, further, the first intermediate member 12 includes: the elastic body support member 121 which is rotatably supported by the first plate member 111 of the drive member 11 and which supports the first and second outer springs SP11 and SP12 so as to be arranged alternately along the circumferential direction; and the coupling member 122 which is coupled so as to rotate together with the turbine runner 5. The elastic body support member 121 has the spring abutment portions 121c which are each provided between the first and second outer springs SP11 and SP12, which are adjacent to each other, so as to abut against the end portions of such first and second outer springs SP11 and SP12. The coupling member 122 has the first spring abutment portions 122c which are each provided between the first and second outer springs SP11 and SP12, which are adjacent to each other, so as to abut against the end portions of such first and second outer springs SP11 and SP12. Consequently, it is possible to couple the first intermediate member 12 to both the first outer springs SP11 and the second outer springs SP12, which are disposed on the radially outer side, and to couple the first intermediate member 12 to the turbine runner 5 while making the entire device compact by suppressing an increase in axial length of the damper device 10.

By coupling the turbine runner 5 (and the turbine hub) to the first intermediate member 12, the substantial moment of inertia of the first intermediate member 12 (the total of the moments of inertia of the elastic body support member 121, the coupling member 122, the turbine runner 5, and so forth) can be further increased. In addition, by causing both the spring abutment portions 121c of the elastic body support member 121 and the spring abutment portions 122c of the coupling member 122 to abut against the end portions of the first and second outer springs SP11 and SP12, it is possible to smoothly expand and contract the first and second outer springs SP11 and SP12.

In the damper device 10, in addition, the drive member 11 includes: the first plate member 111 which has the spring abutment portions 111c which each abut against the end portions of the first outer springs SP11; and the second plate member 112 which has the spring abutment portions 112c which are provided on the radially inner side with respect to the spring abutment portions 111c and which abut against the end portions of the first inner springs SP21 which are included in a second torque transfer path P2. The first plate member 111 is rotatably supported by the first support portion 71 of the damper hub 7. The second plate member 112 is rotatably supported by the second support portion 72 of the damper hub 7 which is provided as shifted in at least the axial direction of the damper device 10 from the first support portion (71).

Consequently, a load applied from the drive member 11, which abuts against both the first outer springs SP11 and the first inner springs SP21, to the damper hub 7 can be distributed to the first and second support portions 71 and 72. Thus, it is possible to secure the strength and the durability of the damper hub 7 while suppressing an increase in axial length etc. As a result, in the damper device 10 which has at least the first and second torque transfer paths P1 and P2, the durability of the damper hub 7 which supports the drive member 11 can be improved while suppressing an increase in size of the entire device. It should be noted, however, that the first support portion which supports the first plate member 111 of the drive member 11 and the second support portion which supports the second plate member 112 may be provided to a member other than the damper hub 7 that is disposed coaxially with the damper hub 7, such as the first or second intermediate member 12 or 14, for example.

Furthermore, by fixing the first plate member 111 to the lock-up piston 80 and fitting the first plate member 111 with the second plate member 112 with backlash in the radial direction (so as to be relatively movable in the radial direction), it is possible to rotate both the first and second plate members 111 and 112 together with each other using torque from the lock-up piston 80 while supporting (aligning) the first and second plate members 111 and 112 so as to be individually rotatable. Additionally, by providing the first support portion 71, which supports the lock-up piston 80 and the first plate member 111, on the radially inner side with respect to the second support portion 72, it is possible to maintain the assemblability of the damper device 10 well, and to sufficiently secure the pressure reception area of the lock-up piston 80 (capacity of the lock-up chamber 85).

In the damper device 10, in addition, the drive member 11 includes the third plate member 113 which has the spring abutment portions 113c which abut against the end portions of the first inner springs SP21 and which is coupled so as to be arranged side by side with the second plate member 112 in the axial direction of the damper device 10. Furthermore, the second and third plate members 112 and 113 support the first and second inner springs SP21 and SP22 such that the first and second inner springs SP21 and SP22 are arranged alternately along the circumferential direction of the damper device 10. In addition, the driven member 16 is disposed between the second and third plate members 112 and 113 in the axial direction, and has the outer spring abutment portions 16co which abut against end portions of the second outer springs SP12 and the inner spring abutment portions 16ci which abut against the end portions of the second inner springs SP22. The second intermediate member 14 is disposed on the opposite side of the third plate member 113 from the driven member 16 in the axial direction of the damper device 10, and has the first spring abutment portions 14c which extend in the axial direction and which are each provided between the first and second inner springs SP21 and SP22, which are adjacent to each other, so as to abut against the end portions of such first and second inner springs SP21 and SP22. Consequently, in the damper device 10, the springs SP11, SP12, SP11, SP12, SP21, SP22, and SPm can be disposed while suppressing complication of the structure.

In the damper device 10, further, the driven member 16 is disposed between the second and third plate members 112 and 113, and the second intermediate member 14 is disposed side by side with the second and third plate members 112 and 113 in the axial direction. Consequently, it is possible to reduce a force (a force in the direction of moving the second and third plate members 112 and 113 apart from each other) applied from the first and second inner springs SP21 and SP22, which receive a centrifugal force during rotation of the drive member 11 etc., to the second and third plate members 112 and 113 via the spring support portions 112b and 113b to deform the second and third plate members 112 and 113 by suppressing an increase in distance between the second and third plate members 112 and 113. Thus, it is possible to secure the strength, durability, etc. of a coupling portion (around the rivets) between the second and third plate members 112 and 113 well while suppressing an increase in size of such a coupling portion and hence the entire damper device 10. As a result, the durability of the second and third plate members 112 and 113 which are coupled to each other, and hence the entire damper device 10, can be improved while suppressing an increase in size of the entire device. Additionally, by causing the first spring abutment portions 14c of the second intermediate member 14 to extend in the axial direction of the damper device 10, it is possible to couple the second intermediate member 14, which is disposed side by side with the second and third plate members 112 and 113 in the axial direction, to both the first and second inner springs SP21 and SP22.

In the damper device 10, in addition, the coupling member 122, which constitutes the first intermediate member 12, rotatably supports the second intermediate member 14, and restricts movement of the second intermediate member 14 toward the turbine runner 5 (one side in the axial direction). Furthermore, the third plate member 113 of the drive member 11 has the movement restriction projecting portions 113s which restrict movement of the second intermediate member 14 in the direction away from the turbine runner 5. Consequently, it is possible to appropriately support the second intermediate member 14, which is disposed side by side with the second and third plate members 112 and 113 of the drive member 11 in the axial direction, using the coupling member 122 (first intermediate member 12).

Next, operation of the damper device 10 will be described. In the starting device 1, when lock-up by the lock-up clutch 8 is released, for example, rotational torque (power) transferred from the engine EG to the front cover 3 is transferred to the input shaft IS of the transmission TM via a path that includes the pump impeller 4, the turbine runner 5, the first intermediate member 12, the second outer springs SP12, the driven member 16, and the damper hub 7 and a path that includes the pump impeller 4, the turbine runner 5, the first intermediate member 12, the intermediate springs SPm, the second intermediate member 14, the second inner springs SP22, the driven member 16, and the damper hub 7. When lock-up is established by the lock-up clutch 8 of the starting device 1, in contrast, rotational torque (input torque) transferred from the engine EG to the drive member 11 via the front cover 3 and the lock-up clutch 8 (lock-up piston 80) is transferred to the driven member 16 and the damper hub 7 via all the springs SP11 to SPm until torque input to the drive member 11 reaches the torque T1 described above, that is, while deflection of all of the first and second outer springs SP11 and SP12, the first and second inner springs SP21 and SP22, and the intermediate springs SPm is allowed.

That is, during a period before input torque reaches the torque T1 during establishment of lock-up, the first outer springs (first elastic bodies) SP11 transfer rotational torque from the drive member 11 to the first intermediate member 12, and the second outer springs (second elastic bodies) SP12 transfer rotational torque from the first intermediate member 12 to the driven member 16. In addition, the first inner springs (third elastic bodies) SP21 transfer rotational torque from the drive member 11 to the second intermediate member 14, and the second inner springs (fourth elastic bodies) SP22 transfer rotational torque from the second intermediate member 14 to the driven member 16. Thus, as illustrated in FIG. 7, the damper device 10 has, as torque transfer paths between the drive member 11 and the driven member 16, the first torque transfer path P1 which includes the first outer springs SP11, the first intermediate member 12, and the second outer springs SP12 and the second torque transfer path P2 which includes the first inner springs SP21, the second intermediate member 14, and the second inner springs SP22.

In the damper device 10, in addition, as discussed above, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22 meet the relation k₁₁<k₁₂<k₂₂<k₂₁. Therefore, when torque is transferred to the drive member 11 during a period before input torque reaches the torque T1 during establishment of lock-up, as illustrated in FIG. 7, the second intermediate member 14 is (slightly) twisted with respect to the first intermediate member 12 toward the advancing direction side (toward the downstream side) in the rotational direction (the rotational direction at the time when the vehicle travels forward). Consequently, the intermediate springs SPm are each pressed by one of the pair of second spring abutment portions 14d of the second intermediate member 14 on the side opposite to the advancing direction side in the rotational direction, toward one of the pair of second spring abutment portions 122d of the first intermediate member 12 on the advancing direction side in the rotational direction. That is, before input torque reaches the torque T1 during execution of lock-up, the intermediate springs SPm transfer a part of torque (a part of average torque) transferred from the drive member 11 to the second intermediate member 14 via the first inner springs SP21, to the first intermediate member 12. Thus, the damper device 10 has a third torque transfer path P3 that includes the first inner springs SP21, the second intermediate member 14, the intermediate springs SPm, the first intermediate member 12, and the second outer springs SP12.

As a result, during a period before torque input to the drive member 11 reaches the torque T1 described above during establishment of lock-up, torque is transferred from the drive member 11 to the driven member 16 via the first, second, and third torque transfer paths P1, P2, and P3. More particularly, while deflection of all of the first and second outer springs SP11 and SP12, the first and second inner springs SP21 and SP22, and the intermediate springs SPm is allowed, rotational torque from the first outer springs SP11 and rotational torque from the first inner springs SP21, the second intermediate member 14, and the intermediate springs SPm are transferred to the second outer springs SP12. In addition, rotational torque from the first inner springs SP21 is transferred to the second inner springs SP22. While deflection of all of the first and second outer springs SP11 and SP12, the first and second inner springs SP21 and SP22, and the intermediate springs SPm is allowed, fluctuations in torque transferred to the drive member 11 are damped (absorbed) by the springs SP11 to SPm. Consequently, it is possible to improve the vibration damping performance of the damper device 10 well when input torque transferred to the drive member 11 is relatively small and the rotational speed of the drive member 11 is low.

In addition, when the first and second stoppers 21 and 22 are caused to operate with torque input to the drive member 11 reaching the torque T1 described above, relative rotation between the first intermediate member 12 and the driven member 16 and deflection of the second outer springs SP12 are restricted by the first stopper 21, and relative rotation between the second intermediate member 14 and the driven member 16 and deflection of the second inner springs SP22 are restricted by the second stopper 22. Consequently, deflection of the intermediate springs SPm is also restricted as relative rotation of the first and second intermediate members 12 and 14 with respect to the driven member 16 is restricted. Thus, the first outer springs SP11 and the first inner springs SP21 act in parallel with each other to damp (absorb) fluctuations in torque transferred to the drive member 11 since torque input to the drive member 11 reaches the torque T1 described above until the input torque reaches the torque T2 described above to cause the third stopper 23 to operate.

Subsequently, the procedure for designing the damper device 10 will be described.

In the damper device 10, as discussed above, while deflection of all of the first and second outer springs SP11 and SP12, the first and second inner springs SP21 and SP22, and the intermediate springs SPm is allowed, torque (average torque) is transferred between the drive member 11 and the driven member 16 via all of the springs SP11 to SPm. The inventors diligently studied and analyzed the damper device 10 which had complicated torque transfer paths which were neither series nor parallel. As a result, the inventors found that such a damper device 10 had two natural frequencies for the entire device while deflection of all of the springs SP11 to SPm is allowed. According to the studies and the analyses conducted by the inventors, in the damper device 10, in addition, when resonance (in the present embodiment, resonance of the first intermediate member 12 at the time when the first and second intermediate members 12 and 14 are vibrated in phase with each other) at the lower one of the two natural frequencies (a natural frequency on the low-rotation side (low-frequency side) is generated in accordance with the frequency of vibration transferred to the drive member 11, the phase of vibration transferred from the second outer springs SP12 to the driven member 16 and the phase of vibration transferred from the second inner springs SP22 to the driven member 16 are shifted from each other. Therefore, as the rotational speed of the drive member 11 becomes higher after resonance at the lower one of the two natural frequencies is generated, one of vibration transferred from the second outer springs SP12 to the driven member 16 and vibration transferred from the second inner springs SP22 to the driven member 16 cancels out at least a part of the other.

With such findings, the inventors formulated an equation of motion indicated by the following formula (1) for a vibration system that included the damper device 10 in which torque was transferred from the engine (internal combustion engine) EG to the drive member 11 through establishment of lock-up. In the formula (1), “J₁” is the moment of inertia of the drive member 11, “J₂₁” is the moment of inertia of the first intermediate member 12, “J₂₂” is the moment of inertia of the second intermediate member 14, and “J₃” is the moment of inertia of the driven member 16. In addition, “θ₁” is the torsional angle of the drive member 11, “θ₂₁” is the torsional angle of the first intermediate member 12, “θ₂₂” is the torsional angle of the second intermediate member 14, and “θ₃” is the torsional angle of the driven member 16. Furthermore, “k₁” is the synthetic spring constant of the plurality of first outer springs SP11 which are provided between the drive member 11 and the first intermediate member 12 to act in parallel with each other, “k₂” is the synthetic spring constant of the plurality of second outer springs SP12 which are provided between the first intermediate member 12 and the driven member 16 to act in parallel with each other, “k₃” is the synthetic spring constant of the plurality of first inner springs SP21 which are provided between the drive member 11 and the second intermediate member 14 to act in parallel with each other, “k₄” is the synthetic spring constant of the plurality of second inner springs SP22 which are provided between the second intermediate member 14 and the driven member 16 to act in parallel with each other, “k₅” is the synthetic spring constant (rigidity) of the plurality of intermediate springs SPm which are provided between the first intermediate member 12 and the second intermediate member 14 to act in parallel with each other, “k_R” is the rigidity, that is, the spring constant, of the transmission TM, a drive shaft, etc. which are disposed between the driven member 16 and the wheels of the vehicle, and “T” is input torque transferred from the engine EG to the drive member 11.

$\begin{matrix} [Expression 1] \\ (\begin{matrix} J_{1} & 0 & 0 & 0 \\ 0 & J_{21} & 0 & 0 \\ 0 & 0 & J_{22} & 0 \\ 0 & 0 & 0 & J_{3} \end{matrix}) (\begin{matrix} {\ddot{θ}}_{1} \\ {\ddot{θ}}_{21} \\ {\ddot{θ}}_{22} \\ {\ddot{θ}}_{3} \end{matrix}) + (\begin{matrix} k_{1} + k_{3} & - k_{1} & - k_{3} & 0 \\ - k_{1} & k_{1} + k_{2} + k_{5} & - k_{5} & - k_{2} \\ - k_{3} & - k_{5} & k_{3} + k_{4} + k_{5} & - k_{4} \\ 0 & - k_{2} & - k_{4} & k_{2} + k_{4} + k_{R} \end{matrix}) (\begin{matrix} θ_{1} \\ θ_{21} \\ θ_{22} \\ θ_{3} \end{matrix}) = (\begin{matrix} T \\ 0 \\ 0 \\ 0 \end{matrix}) & (1) \end{matrix}$

Furthermore, the inventors assumed that the input torque T was vibrated periodically as indicated by the following formula (2), and assumed that the torsional angle θ₁of the drive member 11, the torsional angle θ₂₁of the first intermediate member 12, the torsional angle θ₂₂of the second intermediate member 14, and the torsional angle θ₃of the driven member 16 responded (were vibrated) periodically as indicated by the following formula (3). In the formulas (2) and (3), “ω” is the angular frequency of periodic fluctuations (vibration) of the input torque T. In the formula (3), “Θ₁” is the amplitude (vibration amplitude, i.e. maximum torsional angle) of vibration of the drive member 11 caused along with transfer of torque from the engine EG, “Θ₂₁” is the amplitude (vibration amplitude) of vibration of the first intermediate member 12 caused as torque from the engine EG is transferred to the drive member 11, “Θ₂₂” is the amplitude (vibration amplitude) of vibration of the second intermediate member 14 caused as torque from the engine EG is transferred to the drive member 11, and “Θ₃” is the amplitude (vibration amplitude) of vibration of the driven member 16 caused as torque from the engine EG is transferred to the drive member 11. Under such assumptions, an identity of the following formula (4) can be obtained by substituting the formulas (2) and (3) into the formula (1) and dividing both sides by “sin ωt”.

$\begin{matrix} [Expression 2] \\ T = T_{0} \sin ω t & (2) \\ [\begin{matrix} θ_{1} \\ θ_{21} \\ θ_{22} \\ θ_{3} \end{matrix}] = [\begin{matrix} Θ_{1} \\ Θ_{21} \\ Θ_{22} \\ Θ_{3} \end{matrix}] \sin ω t & (3) \\ (\begin{matrix} - ω^{2} J_{1} + k_{1} + k_{3} & - k_{1} & - k_{3} & 0 \\ - k_{1} & - ω^{2} J_{21} + k_{1} + k_{2} + k_{5} & - k_{5} & - k_{2} \\ - k_{3} & - k_{5} & - ω^{2} J_{22} + k_{3} + k_{4} + k_{5} & - k_{4} \\ 0 & - k_{2} & - k_{4} & - ω^{2} J_{3} + k_{2} + k_{4} + k_{R} \end{matrix}) (\begin{matrix} Θ_{1} \\ Θ_{21} \\ Θ_{22} \\ Θ_{3} \end{matrix}) = (\begin{matrix} T \\ 0 \\ 0 \\ 0 \end{matrix}) & (4) \end{matrix}$

The inventors then focused on the fact that, if the vibration amplitude Θ₃of the driven member 16 in the formula (4) became zero, no vibration was transferred in theory to the transmission TM, the drive shaft, etc. in a stage subsequent to the driven member 16 as vibration from the engine EG is damped by the damper device 10. Thus, from such a viewpoint, the inventors obtained a conditional expression indicated by the following formula (5) by solving the identity of the formula (4) for the vibration amplitude Θ₃and setting Θ₃to zero. In the case where the relationship of the formula (5) is met, vibrations from the engine EG transferred from the drive member 11 to the driven member 16 via the first, second, and third torque transfer paths P1, P2, and P3 cancel out each other, and the vibration amplitude Θ₃of the driven member 16 becomes zero in theory.

$\begin{matrix} [Expression 3] \\ ω^{2} = \frac{k_{5} \cdot (k_{1} + k_{3}) \cdot (k_{2} + k_{4}) + k_{1} k_{2} k_{3} + k_{1} k_{2} k_{4} + k_{1} k_{3} k_{4} + k_{2} k_{3} k_{4}}{J_{21} k_{3} k_{4} + J_{22} k_{1} k_{2}} & (5) \end{matrix}$

From such analysis results, it is understood that, with the damper device 10 configured as discussed above, an antiresonance point A at which the vibration amplitude Θ3 (torque fluctuations) of the driven member 16 becomes zero in theory as indicated in FIG. 8 may be set because the phase of vibration transferred from the second outer springs SP12 to the driven member 16 and the phase of vibration transferred from the second inner springs SP22 to the driven member 16 are shifted by 180 degrees (inverted) from each other through generation of resonance at the lower one of the two natural frequencies so that the vibrations cancel out each other. In addition, by defining the frequency of the antiresonance point A as “fa” and substituting “ω=2πfa” into the formula (5) given above, the frequency fa of the antiresonance point A is represented by the following formula (6). FIG. 8 indicates an example of the relationship between the rotational speed of the engine EG and the vibration amplitude (torque fluctuations) in theory (under the assumption that no hysteresis is provided) of the driven members of the damper device according to the present disclosure and a damper device from which the intermediate springs SPm have been omitted (the damper device described in Published Japanese Translation of PCT Application No. 2012-506006; hereinafter referred to as a “damper device according to a comparative example”).

$\begin{matrix} [Expression 4] \\ fa = \frac{1}{2 π} \sqrt{\frac{k_{5} \cdot (k_{1} + k_{3}) \cdot (k_{2} + k_{4}) + k_{1} k_{2} k_{3} + k_{1} k_{2} k_{4} + k_{1} k_{3} k_{4} + k_{2} k_{3} k_{4}}{J_{21} k_{3} k_{4} + J_{22} k_{1} k_{2}}} & (6) \end{matrix}$

If it is assumed that the torsional angle θ₁of the drive member 11 and the torsional angle θ₂of the driven member 16 are zero and both displacements of the drive member 11 and the driven member 16 are zero, meanwhile, the formula (1) can be transformed into the following formula (7). Furthermore, if it is assumed that the first and second intermediate members 12 and 14 are vibrated in harmony with each other as indicated by the following formula (8), an identity of the following formula (9) can be obtained by substituting the formula (8) into the formula (7) and dividing both sides by “sin ωt”.

$\begin{matrix} [Expression 5] \\ (\begin{matrix} J_{21} & 0 \\ 0 & J_{22} \end{matrix}) (\begin{matrix} {\ddot{θ}}_{21} \\ {\ddot{θ}}_{22} \end{matrix}) + (\begin{matrix} k_{1} + k_{2} + k_{5} & - k_{5} \\ - k_{5} & k_{3} + k_{4} + k_{5} \end{matrix}) (\begin{matrix} θ_{21} \\ θ_{22} \end{matrix}) = (\begin{matrix} 0 \\ 0 \end{matrix}) & (7) \\ (\begin{matrix} θ_{21} \\ θ_{22} \end{matrix}) = (\begin{matrix} Θ_{21} \\ Θ_{22} \end{matrix}) \sin ω t & (8) \\ (\begin{matrix} - ω^{2} J_{21} + k_{1} + k_{2} + k_{3} & - k_{5} \\ - k_{5} & - ω^{2} J_{22} + k_{3} + k_{4} + k_{5} \end{matrix}) (\begin{matrix} Θ_{21} \\ Θ_{22} \end{matrix}) = (\begin{matrix} 0 \\ 0 \end{matrix}) & (9) \end{matrix}$

In the case where the first and second intermediate members 12 and 14 are vibrated in harmony with each other, both the amplitudes Θ₂₁and Θ₂₂are not zero. Thus, the determinant of the square matrix on the left side of the formula (9) is zero, and a conditional expression of the following formula (10) must be met. Such a formula (10) is a quadratic equation for the square value ω²of two natural angular frequencies of the damper device 10. Thus, the two natural angular frequencies ω₁and ω₂of the damper device 10 are represented by the following formulas (11) and (12), and ω₁<ω₂is met. As a result, if the frequency of resonance (resonance point R1) that causes the resonance point A, that is, the natural frequency of the first intermediate member 12, is defined as “f₂₁”, and if the frequency of resonance (resonance point R2) generated on the high-rotation side with respect to the antiresonance point A, that is, the natural frequency of the second intermediate member 14, is defined as “f₂₂”, the natural frequency f₂₁on the low-rotation side (low-frequency side) is represented by the following formula (13), and the natural frequency f₂₂(f₂₂>f₂₁) on the high-rotation side (high-frequency side) is represented by the following formula (14).

$\begin{matrix} [Expression 6] \\ (- ω^{2} J_{21} + k_{1} + k_{2} + k_{5}) (- ω^{2} J_{22} + k_{3} + k_{4} + k_{5}) - k_{5}^{2} = 0 & (10) \\ ω_{1} = \sqrt{\frac{1}{2} {\begin{matrix} \frac{k_{1} + k_{2} + k_{5}}{J_{21}} + \frac{k_{3} + k_{4} + k_{5}}{J_{22}} - \\ \sqrt{{(\frac{k_{3} + k_{4} + k_{5}}{J_{22}} - \frac{k_{1} + k_{2} + k_{5}}{J_{21}})}^{2} + \frac{4 k_{5}^{2}}{J_{21} J_{22}}} \end{matrix}}} & (11) \\ ω_{2} = \sqrt{\frac{1}{2} {\begin{matrix} \frac{k_{1} + k_{2} + k_{5}}{J_{21}} + \frac{k_{3} + k_{4} + k_{5}}{J_{22}} + \\ \sqrt{{(\frac{k_{3} + k_{4} + k_{5}}{J_{22}} - \frac{k_{1} + k_{2} + k_{5}}{J_{21}})}^{2} + \frac{4 k_{5}^{2}}{J_{21} J_{22}}} \end{matrix}}} & (12) \\ f_{21} = \frac{1}{2 π} \sqrt{\begin{matrix} \frac{k_{1} + k_{2} + k_{5}}{2 J_{21}} + \frac{k_{3} + k_{4} + k_{5}}{2 J_{22}} - \\ \sqrt{{(\frac{k_{3} + k_{4} + k_{5}}{2 J_{22}} - \frac{k_{1} + k_{2} + k_{5}}{2 J_{21}})}^{2} + \frac{k_{5}^{2}}{J_{21} J_{22}}} \end{matrix}} & (13) \\ f_{22} = \frac{1}{2 π} \sqrt{\begin{matrix} \frac{k_{1} + k_{2} + k_{5}}{2 J_{21}} + \frac{k_{3} + k_{4} + k_{5}}{2 J_{22}} + \\ \sqrt{{(\frac{k_{3} + k_{4} + k_{5}}{2 J_{22}} - \frac{k_{1} + k_{2} + k_{5}}{2 J_{21}})}^{2} + \frac{k_{5}^{2}}{J_{21} J_{22}}} \end{matrix}} & (14) \end{matrix}$

In addition, an equivalent rigidity k_eqof the damper device 10 at the time when deflection of all of the first and second outer springs SP11 and SP12, the first and second inner springs SP21 and SP22, and the intermediate springs SPm is allowed can be obtained as follows. That is, if it is assumed that constant input torque T=T₀(static external force) is transferred to the drive member 11, and if it is assumed that the balanced relationship indicated by the following formula (15) is met, an identity of the following formula (16) can be obtained by substituting T=T₀and the formula (15) into the formula (1).

$\begin{matrix} [Expression 7] \\ [\begin{matrix} θ_{1} \\ θ_{21} \\ θ_{22} \\ θ_{3} \end{matrix}] = [\begin{matrix} Θ_{1} \\ Θ_{21} \\ Θ_{22} \\ Θ_{3} \end{matrix}] & (15) \\ (\begin{matrix} k_{1} + k_{3} & - k_{1} & - k_{3} & 0 \\ - k_{1} & k_{1} + k_{2} + k_{5} & - k_{5} & - k_{2} \\ - k_{3} & - k_{5} & k_{3} + k_{4} + k_{5} & - k_{4} \\ 0 & - k_{2} & - k_{4} & k_{2} + k_{4} + k_{R} \end{matrix}) (\begin{matrix} Θ_{1} \\ Θ_{21} \\ Θ_{22} \\ Θ_{3} \end{matrix}) = (\begin{matrix} T_{0} \\ 0 \\ 0 \\ 0 \end{matrix}) & (16) \end{matrix}$

Furthermore, a relation T₀=k_eq·(Θ₁−Θ₃) is met among the torque T₀, the equivalent rigidity k_eqof the damper device 10, the vibration amplitude (torsional angle) Θ₁of the drive member 11, and the vibration amplitude (torsional angle) Θ₃of the driven member 16. Furthermore, when the identity of the formula (16) is solved for the vibration amplitudes (torsional angles) Θ₁and Θ₃, “Θ₁−Θ₃” is represented by the following formula (17). Thus, the equivalent rigidity k_eqof the damper device 10 is represented by the following formula (18) using T₀=k_eq·(Θ₁−Θ₃) and the formula (17).

$\begin{matrix} [Expression 8] \\ Θ_{1} - Θ_{3} = \frac{{k_{5} \cdot (k_{1} + k_{2} + k_{3} + k_{4}) + (k_{1} + k_{2}) (k_{3} + k_{4})} T_{0}}{k_{5} (k_{1} + k_{3}) (k_{2} + k_{4}) + (k_{1} k_{2} k_{3} + k_{1} k_{2} k_{4} + k_{1} k_{3} k_{4} + k_{2} k_{3} k_{4})} & (17) \\ K_{eq} = \frac{k_{5} (k_{1} + k_{3}) (k_{2} + k_{4}) + (k_{1} k_{2} k_{3} + k_{1} k_{3} k_{4} + k_{1} k_{2} k_{4} + k_{2} k_{3} k_{4})}{k_{5} (k_{1} + k_{2} + k_{3} + k_{4}) + (k_{1} + k_{2}) (k_{3} + k_{4})} & (18) \end{matrix}$

The results of analysis conducted by the inventors on the natural frequency f₂₁on the low-rotation side, the frequency fa of the antiresonance point A, and the equivalent rigidity k_eqof the damper device 10 obtained as discussed above are indicated in FIGS. 9 to 14. FIGS. 9 to 14 indicate the mode of variations in the natural frequency f₂₁, the frequency fa of the antiresonance point A, and the equivalent rigidity k_eqat the time when only one of the synthetic spring constants k₁, k₂, k₃, k₄, and k₅and the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14 is varied while keeping the others of the parameters at constant values (fixed values).

In the case where only the synthetic spring constant (rigidity) k₁of the first outer springs (first elastic bodies) SP11 is varied while keeping the synthetic spring constants k₂, k₃, k₄, and k₅and the moments of inertia J₂₁and J₂₂in the damper device 10 at constant values, as indicated in FIG. 9, the natural frequency f₂, and the frequency fa of the antiresonance point A become higher as the synthetic spring constant k₁is larger, and become gradually lower as the synthetic spring constant k₁becomes smaller. In contrast, as illustrated in FIG. 9, the equivalent rigidity k_eqis increased steeply when the synthetic spring constant k₁is increased slightly from a value adapted in advance, and decreased steeply when the synthetic spring constant k₁is decreased slightly from the adapted value. That is, variations (variation gradient) in the equivalent rigidity k_eqare very large with respect to variations in the synthetic spring constant k₁of the first outer springs SP11.

Meanwhile, in the case where only the synthetic spring constant (rigidity) k₂of the second outer springs (second elastic bodies) SP12 is varied while keeping the synthetic spring constants k₁, k₃, k₄, and k₅and the moments of inertia J₂₁and J₂₂in the damper device 10 at constant values, as indicated in FIG. 10, the natural frequency f₂₁and the frequency fa of the antiresonance point A become higher as the synthetic spring constant k₂is larger, and become gradually lower as the synthetic spring constant k₂becomes smaller. Furthermore, as illustrated in FIG. 10, the equivalent rigidity k_eqis increased steeply when the synthetic spring constant k₂is increased slightly from a value adapted in advance, and decreased steeply when the synthetic spring constant k₂is decreased slightly from the adapted value. That is, variations (variation gradient) in the equivalent rigidity k_eqare also very large with respect to variations in the synthetic spring constant k₂of the second outer springs SP12.

On the other hand, in the case where only the synthetic spring constant (rigidity) k₃of the first inner springs (third elastic bodies) SP21 is varied while keeping the synthetic spring constants k₁, k₂, k₄, and k₅and the moments of inertia J₂₁and J₂₂in the damper device 10 at constant values, as indicated in FIG. 11, the natural frequency f₂₁becomes slightly higher (is kept generally constant) as the synthetic spring constant k₃becomes larger, and the frequency fa of the antiresonance point A becomes higher as the synthetic spring constant k₃is smaller, and becomes gradually lower as the synthetic spring constant k₃becomes larger. In addition, as illustrated in FIG. 11, the equivalent rigidity k_eqis decreased steeply when the synthetic spring constant k₃is decreased slightly from a value adapted in advance, and increased steeply when the synthetic spring constant k₃is increased slightly from the adapted value. That is, variations (variation gradient) in the equivalent rigidity k are also very large with respect to variations in the synthetic spring constant k₃of the first inner springs SP21.

Furthermore, also in the case where only the synthetic spring constant (rigidity) k₄of the second inner springs (fourth elastic bodies) SP22 is varied while keeping the synthetic spring constants k₁, k₂, k₃, and k₅and the moments of inertia J₂₁and J₂₂in the damper device 10 at constant values, as indicated in FIG. 12, the natural frequency f₂₁becomes slightly higher (is kept generally constant) as the synthetic spring constant k₄becomes larger, and the frequency fa of the antiresonance point A becomes higher as the synthetic spring constant k₄is smaller, and becomes gradually lower as the synthetic spring constant k₄becomes larger. In addition, as illustrated in FIG. 12, the equivalent rigidity k_eqis decreased steeply when the synthetic spring constant k₄is decreased slightly from a value adapted in advance, and increased steeply when the synthetic spring constant k₄is increased slightly from the adapted value. That is, variations (variation gradient) in the equivalent rigidity k_eqare also very large with respect to variations in the synthetic spring constant k₄of the second inner springs SP22.

In the case where only the synthetic spring constant (rigidity) k₅of the intermediate springs (fifth elastic bodies) SPm is varied while keeping the synthetic spring constants k₁, k₂, k₃, and k₄and the moments of inertia J₂₁and J₂₂in the damper device 10 at constant values, as indicated in FIG. 13, the natural frequency f₂₁and the frequency fa of the antiresonance point A become higher as the synthetic spring constant k₅is larger, and become gradually lower as the synthetic spring constant k₅becomes smaller. In addition, as illustrated in FIG. 13, the difference (fa−f₂₁) between the natural frequency f₂₁and the frequency fa of the antiresonance point A corresponding to a certain synthetic spring constant k₅becomes gradually larger as the synthetic spring constant k₅becomes larger. Furthermore, in the case where only the synthetic spring constant k₅of the intermediate springs SPm is varied, as illustrated in FIG. 13, the equivalent rigidity k_eqbecomes higher as the synthetic spring constant k₅is larger, and becomes gradually lower as the synthetic spring constant k₅becomes smaller. That is, variations (variation gradient) in the equivalent rigidity k_eqwith respect to variations in the synthetic spring constant (rigidity) k₅of the intermediate springs SPm are significantly small compared to variations (variation gradient) in the equivalent rigidity k_eqwith respect to variations in the synthetic spring constants (rigidities) k₁, k₂, k₃, and k₄.

Meanwhile, in the case where only the moment of inertia J₂₁of the first intermediate member 12 is varied while keeping the synthetic spring constants k₁, k₂, k₃, k₄, and k₅and the moment of inertia J₂₂of the second intermediate member 14 in the damper device 10 at constant values, as indicated in FIG. 14, the natural frequency f₂₁and the frequency fa of the antiresonance point A become higher as the moment of inertia J₂₁is smaller, and become gradually lower as the moment of inertia J₂₁becomes larger. Furthermore, if only the moment of inertia J₂₁of the first intermediate member 12 is varied, as illustrated in FIG. 14, the equivalent rigidity k_eqis kept generally constant. Moreover, in the case where only the moment of inertia J₂₂of the second intermediate member 14 is varied while keeping the synthetic spring constants k₁, k₂, k₃, k₄, and k₅and the moment of inertia J₂₁of the first intermediate member 12 in the damper device 10 at constant values, although not indicated in the drawings, results similar to those obtained in the case where only the moment of inertia J₂₁of the first intermediate member 12 is varied are obtained.

As seen from the analysis results discussed above, by lowering the rigidity of the intermediate springs SPm (reducing the spring constant k_mand the synthetic spring constant K₅), it is possible to reduce the natural frequency f₂₁on the low-rotation side (see the formula (13)) and the frequency fa of the antiresonance point A (see the formula (6)). By enhancing the rigidity of the intermediate springs SPm (increasing the spring constant k_mand the synthetic spring constant K₅), conversely, it is possible to increase the difference between the natural frequency f₂₁on the low-rotation side and the frequency fa of the antiresonance point A. Furthermore, the equivalent rigidity k_eqis not lowered significantly even if the rigidity of the intermediate springs SPm is lowered (even if the spring constant k_mand the synthetic spring constant K₅arc reduced). Thus, in the damper device 10, by adjusting the rigidity (the spring constant k_mand the synthetic spring constant K₅) of the intermediate springs SPm, it is possible to appropriately set the natural frequency f₂₁on the low-rotation side and the frequency fa of the antiresonance point A while keeping the equivalent rigidity k_eqappropriate in accordance with the maximum torque input to the drive member 11 and suppressing an increase in weights of the first and second intermediate members 12 and 14, that is, the moments of inertia J₂₁and J₂₂. By lowering the rigidities of the first and second outer springs SP11 and SP12 (reducing the spring constants k₁₁and k₁₂and the synthetic spring constants K₁and K₂), in addition, it is possible to reduce the natural frequency f₂₁on the low-rotation side and the frequency fa of the antiresonance point A. By enhancing the rigidities of the first and second inner springs SP21 and SP22 (increasing the spring constants k₂₁and k₂₂and the synthetic spring constants K₃and K₄), further, it is possible to reduce the frequency fa of the antiresonance point A.

In the vehicle on which the engine (internal combustion engine) EG is mounted as a source that generates power for travel, the efficiency of power transfer between the engine EG and the transmission TM can be improved, and the fuel efficiency of the engine EG can be improved, by lowering a lock-up rotational speed Nlup so that torque from the engine EG is mechanically transferred to the transmission TM early. It should be noted, however, that in a low-rotational speed range of about 500 rpm to 1500 rpm, in which the lock-up rotational speed Nlup may be set, vibration transferred from the engine EG to the drive member 11 via a lock-up clutch is increased, and that the vibration level is increased remarkably in vehicles on which an engine with a reduced number of cylinders such as a three-cylinder or four-cylinder engine, in particular, is mounted. Thus, in order that large vibration is not transferred to the transmission TM etc. during or immediately after establishment of lock-up, it is necessary to lower the vibration level in a rotational speed range around the lock-up rotational speed Nlup of the entire damper device 10 (driven member 16) which transfers torque (vibration) from the engine EG to the transmission TM when lock-up is established.

In the light of this, the inventors configured the damper device 10 such that the antiresonance point A discussed above was formed when the rotational speed of the engine EG was in the range of 500 rpm to 1500 rpm (the assumed setting range of the lock-up rotational speed Nlup) on the basis of the lock-up rotational speed Nlup which was determined for the lock-up clutch 8. If the number of cylinders of the engine (internal combustion engine) EG is defined as “n”, a rotational speed Nea of the engine EG corresponding to the frequency fa of the antiresonance point A is represented as Nea=(120/n)·fa. Thus, in the damper device 10, the synthetic spring constant k₁of the plurality of first outer springs SP11, the synthetic spring constant k₂of the plurality of second outer springs SP12, the synthetic spring constant k₃of the plurality of first inner springs SP21, the synthetic spring constant k₄of the plurality of second inner springs SP22, the synthetic spring constant k₅of the plurality of intermediate springs SPm, the moment of inertia J₂₁of the first intermediate member 12 (with the moment of inertia of the turbine runner 5 etc., which is coupled so as to rotate therewith, taken into consideration (added); the same applies hereinafter), and the moment of inertia J₂₂of the second intermediate member 14 are selected and set so as to meet the following formula (19). That is, in the damper device 10, the spring constants k₁₁, k₁₂, k₂₁, k₂₂, and k_mof the springs SP11 to SPm and the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14 are selected and set on the basis of the frequency fa of the antiresonance point A (and the lock-up rotational speed Nlup).

$\begin{matrix} [Expression 9] \\ 500 rpm \leq \frac{120}{n} fa \leq 1500 rpm & (19) \end{matrix}$

In this way, by setting the antiresonance point A which may bring the vibration amplitude Θ₃of the driven member 16 to zero in theory (which may lower vibration) within the low-rotational speed range from 500 rpm to 1500 rpm (the assumed setting range of the lock-up rotational speed Nlup), as indicated in FIG. 8, resonance that causes the antiresonance point A (resonance unavoidably caused in order to form the antiresonance point A; in the present embodiment, resonance of the first intermediate member 12; see the resonance point R1 in FIG. 8) can be shifted to the lower-rotation side (lower-frequency side) so as to be included in a non-lock-up region of the lock-up clutch 8 (see the dash-double-dot line in FIG. 8). That is, in the present embodiment, resonance of the first intermediate member 12 (resonance at the lower one of the two natural frequencies) is virtual and not generated in a rotational speed range in which the damper device 10 is used. In addition, as indicated in FIG. 8, a rotational speed corresponding to the lower one of the two natural frequencies of the damper device 10 (the natural frequency of the first intermediate member 12) is lower than the lock-up rotational speed Nlup of the lock-up clutch 8, and a rotational speed corresponding to the higher one of the two natural frequencies of the damper device 10 (the natural frequency of the second intermediate member 14) is higher than the lock-up rotational speed Nlup. Consequently, one of vibration transferred from the second outer springs SP12 to the driven member 16 and vibration transferred from the second inner springs SP22 to the driven member 16 can be used to cancel out at least a part of the other since the time when lock-up is established by the lock-up clutch 8.

To configure the damper device 10 so as to meet the formula (19) given above, the spring constants k₁₁, k₁₂, k₂₁, k₂₂, and k_mand the moments of inertia J₂₁and J₂₂are preferably selected and set such that the frequency of resonance that causes the antiresonance point A (see the resonance point R1 in FIG. 8) is lower than the frequency fa of the antiresonance point A and is as small a value as possible. Therefore, in the damper device 10 according to the present embodiment, the values of the spring constants k₁₁, k₁₂, k₂₁, k₂₂, and k_mare determined so as to meet the relation k_1l<k_m<k₁₂<k₂₂<k₂₁discussed above.

That is, in the damper device 10, the spring constant k_mof the intermediate springs SPm and the spring constants k₁₁and k₁₂of the first and second outer springs SP11 and SP12 are determined to be small such that the natural frequency f21 on the low-rotation side and the frequency fa of the antiresonance point A is reduced more. Furthermore, the spring constants k₂₁and k₂₂of the first and second inner springs SP21 and SP22 are determined to be large such that the natural frequency f₂₁on the low-rotation side is reduced more. Consequently, it is possible to set the start point of a rotational speed band (frequency band) in which one of vibration transferred from the second outer springs SP12 to the driven member 16 and vibration transferred from the second inner springs SP22 to the driven member 16 is used to cancel out at least a part of the other on the lower-rotation side (lower-frequency side) by reducing the natural frequency f₂₁on the low-rotation side and the frequency fa of the antiresonance point A. By setting the start point of such a rotational speed band on the low-rotation side, further, the rotational speed (frequency) at which the phase of vibration transferred from the second outer springs SP12 to the driven member 16 and the phase of vibration transferred from the second inner springs SP22 to the driven member 16 are shifted by 180 degrees from each other can also be set to the low-rotation side. As a result, it is possible to allow lock-up at a still lower rotational speed, and to further improve the vibration damping performance in the low-speed range.

In addition, in the damper device 10, as indicated in FIG. 8, when the rotational speed of the engine EG is further enhanced after damping of vibration of the driven member 16 peaks around the antiresonance point A, resonance (in the present embodiment, resonance of the second intermediate member 14; see the resonance point R2 in FIG. 8) at the higher one of the two natural frequencies is generated, and vibration transferred from the second outer springs SP12 to the driven member 16 and vibration transferred to from the second inner springs SP22 to the driven member 16 are brought into phase with each other. That is, in the damper device 10 according to the present embodiment, one of vibration transferred from the second outer springs SP12 to the driven member 16 and vibration transferred from the second inner springs SP22 to the driven member 16 cancels out at least a part of the other during a period since resonance (resonance of the first intermediate member 12) at the lower one of the two natural frequencies described above is generated until resonance (resonance of the second intermediate member 14) at the higher one of the two natural frequencies is generated. Thus, the spring constants (synthetic spring constants) k₁, k₂, k₃, k₄, and k₅and the moments of inertia J₂₁and J₂₂are preferably selected and set such that the frequency of resonance generated on the high-rotation side (high-frequency side) with respect to the antiresonance point A is higher. Consequently, it is possible to generate such resonance (resonance point R2) in the high-rotational speed range in which vibration does not easily become manifest, which further improves the vibration damping performance of the damper device 10 in the low-rotational speed range.

Furthermore, in the damper device 10, in order to improve the vibration damping performance around the lock-up rotational speed Nlup, it is necessary to separate the lock-up rotational speed Nlup and the rotational speed of the engine EG corresponding to the resonance point R2 from each other as much as possible. Thus, in configuring the damper device 10 so as to meet the formula (19), the spring constants k₁, k₂, k₃, k₄, and k₅and the moments of inertia J₂₁and J₂₂are preferably selected and set so as to meet Nlup≦(120/n)·fa (=Nea). Consequently, it is possible for the lock-up clutch 8 to establish lock-up while suppressing transfer of vibration to the input shaft IS of the transmission TM well, and for the damper device 10 to damp vibration from the engine EG extremely well immediately after the establishment of lock-up.

As discussed above, by designing the damper device 10 on the basis of the frequency fa of the antiresonance point A, it is possible to improve the vibration damping performance of the damper device 10 extremely well. The studies and the analyses conducted by the inventors confirmed that, in the case where the lock-up rotational speed Nlup is determined as a value around 1000 rpm, for example, extremely good results in practice were obtained by configuring the damper device 10 so as to meet 900 rpm≦(120/n)·fa≦1200 rpm, for example.

In addition, as seen from the formulas (13) and (14), the two natural frequencies f₂₁and f₂₂of the damper device 10 are affected by both the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14. That is, in the damper device 10, the first intermediate member 12 and the second intermediate member 14 are coupled to each other via the intermediate springs SPm. Thus, vibration of the first intermediate member 12 and vibration of the second intermediate member 14 are coupled to each other (vibrations of the first and second intermediate members 12 and 14 affect each other) with a force from the intermediate springs SPm (see the white arrows in FIG. 7) acting on both the first and second intermediate members 12 and 14. In this way, with vibration of the first intermediate member 12 and vibration of the second intermediate member 14 coupled to each other, the natural frequencies f₂₁and f₂₂are affected by both the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14. Thus, in the damper device 10, it is possible to easily shift resonance at the lower one of the two natural frequencies f₂₁and f₂₂to the low-rotation side, that is, the non-lock-up region, while suppressing an increase in weights of the first and second intermediate members 12 and 14, that is, the moments of inertia J₂₁and J₂₂, and to set the natural frequencies f₂₁and f₂₂and the frequency fa of the antiresonance point A easily and appropriately such that the vibrations cancel out each other at the driven member 16 better when the rotational speed of the drive member 11 is lower.

Furthermore, in the damper device 10, the two natural frequencies f₂₁and f₂₂are affected by both the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14. Thus, by adjusting the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14, as indicated in FIG. 8, the natural frequency f₂₁(resonance point R1) on the low-rotation side can be easily shifted to the lower-rotation side of the non-lock-up region compared to the damper device according to the comparative example described above while determining the frequency fa of the antiresonance point A as a value about a frequency fa′ of the antiresonance point of the damper device according to the comparative example. Consequently, with the damper device 10, it is possible to lower the vibration level around the antiresonance point A compared to the damper device according to the comparative example (see the broken line in FIG. 8). In this way, by lowering the vibration level around the antiresonance point A by reducing the natural frequency f₂₁on the low-rotation side, it is possible to keep the lock-up rotational speed Nlup lower even in the case where the order of vibration from the engine EG is lowered along with execution of reduced cylinder operation of the engine EG which has a cylinder stop function.

In addition, the analysis conducted by the inventors has revealed that, by coupling vibrations of the first and second intermediate members 12 and 14 to each other by coupling the first and second intermediate members 12 and 14 to each other using the intermediate springs SPm, vibrations transferred from the first, second, and third torque transfer paths P1, P2, and P3 described above to the driven member 16 tend to cancel out each other, which may reduce the actual vibration amplitude of the driven member 16 around the antiresonance point A and decrease the difference in torque amplitude (torque fluctuations) between the second outer springs SP12 and the second inner springs SP22 (bring the torque amplitudes of the second outer springs SP12 and the second inner springs SP22 closer to each other). Thus, with the damper device 10, it is possible to allow lock-up (coupling between the engine EG and the drive member 11) at lower rotational speeds, and to improve the vibration damping performance in the low-rotational speed range in which vibration from the engine EG tends to become large.

Here, assuming k₅=0 in the formula (13) given above, a natural frequency f₂₁′ of the first intermediate member in the damper device according to the comparative example from which the intermediate springs SPm have been omitted is represented by the following formula (20). Assuming k₅=0 in the formula (14) given above, a natural frequency f₂₂′ of the second intermediate member in the damper device according to the comparative example is represented by the following formula (21). In the damper device according to the comparative example, as seen from the formulae (20) and (21), the natural frequency f₂₁′ of the first intermediate member is not affected by the moment of inertia J₂₂of the second intermediate member, and the natural frequency f₂₂of the second intermediate member is not affected by the moment of inertia J₂₁of the first intermediate member. From this respect, it is understood that, with the damper device 10, the degree of freedom in design of the natural frequencies f₂₁and f₂₂of the first and second intermediate members 12 and 14 may be improved compared to the damper device according to the comparative example.

$\begin{matrix} [Expression 10] \\ f_{21}^{'} = \frac{1}{2 π} \sqrt{\frac{k_{1} + k_{2}}{J_{21}}} & (20) \\ f_{22}^{'} = \frac{1}{2 π} \sqrt{\frac{k_{3} + k_{4}}{J_{22}}} & (21) \end{matrix}$

In addition, assuming k₅=0 in the formula (6) given above, the frequency fa′ of the antiresonance point in the damper device according to the comparative example is represented by the following formula (22). When the formula (6) and the formula (22) are compared with each other, in the case where the spring constants k₁, k₂, k₃, and k₄and the moments of inertia J₂₁and J₂₂are the same, the vibration amplitude fa′ of the antiresonance point in the damper device according to the comparative example is smaller than the frequency fa of the antiresonance point A in the damper device 10. It should be noted, however, that with the damper device 10, the value of the frequency fa of the antiresonance point A can be easily set to a value about the frequency fa′ of the antiresonance point of the damper device according to the comparative example (see the broken line in FIG. 8) by mainly selecting the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14 as appropriate.

$\begin{matrix} [Expression 11] \\ {fa}^{'} = \frac{1}{2 π} \sqrt{\frac{k_{1} k_{2} k_{3} + k_{1} k_{2} k_{4} + k_{1} k_{3} k_{4} + k_{2} k_{3} k_{4}}{J_{21} k_{3} k_{4} + J_{22} k_{1} k_{2}}} & (22) \end{matrix}$

In the damper device 10 discussed above, the first and second outer springs SP11 and SP12 which have a spring constant (rigidity) that is smaller than that of the first and second inner springs SP21 and SP22 are disposed on the outer side of the first and second inner springs SP21 and SP22 in the radial direction of the damper device 10. Consequently, it is possible to increase the moment of inertia J₂₁of the first intermediate member 12, and to lower the rigidity of the first and second outer springs SP11 and SP12, so that the natural frequency (f₂₁) of the first intermediate member 12 is further lowered. In the damper device 10, in addition, the first and second outer springs SP11 and SP12 which have a low rigidity and a relatively light weight are disposed on the outer peripheral side of the damper device 10, and the first and second inner springs SP21 and SP22 which have a high rigidity and a relatively heavy weight are disposed on the center axis CA side of the damper device 10. Consequently, the hystereses of the first and second outer springs SP11 and SP12 on the outer peripheral side can be reduced by the weight reduction of the first and second outer springs SP11 and SP12 due to the low rigidity, and the hystereses of the first and second inner springs SP21 and SP22 on the inner peripheral side can be reduced by lowering a centrifugal force that acts on the first and second inner springs SP21 and SP22. Thus, with the damper device 10, it is possible to reduce the hysteresis of the entire device by reducing a friction force generated between the springs SP11, SP12, SP21, and SP22 and the associated rotary elements because of a centrifugal force. As a result, the vibration damping performance of the damper device 10 can be improved extremely well by bringing the antiresonance point A described above closer to the frequency of vibration (resonance) to be damped.

Furthermore, in the damper device 10 according to the present embodiment, the first intermediate member 12 is configured such that the moment of inertia J₂₁is larger than the moment of inertia J₂₂of the second intermediate member 14, and further the first intermediate member 12 is coupled to the turbine runner 5 so as to rotate therewith. Consequently, it is possible to further lower the vibration level around the antiresonance point A by further reducing the natural frequency f₂₁on the low-frequency side. In addition, by coupling the first intermediate member 12 so as to rotate together with the turbine runner 5, the substantial moment of inertia J₂₁of the first intermediate member 12 (the total of the moments of inertia of the first intermediate member 12, the turbine runner 5, etc.) can be increased. Consequently, it is possible to set the resonance point of the first intermediate member 12 on the lower-rotation side (lower-frequency side) by further reducing the natural frequency f₂₁on the low-frequency side.

The basic procedure for designing the damper device 10 under the assumption that no hysteresis is provided has been described so far. However, it is practically extremely difficult to eliminate the hysteresis in the damper device 10 which includes the plurality of springs SP11, SP12, SP21, SP22, and SPm. In the damper device 10 which includes the first and second torque transfer paths P1 and P2, in addition, the frequency at which the phase of vibration transferred from the second outer springs SP12 to the driven member 16 is shifted by 180 degrees with respect to the phase of vibration transferred from the second inner springs SP22 to the driven member 16 may be shifted to the high-frequency side (high-rotation side) from the theoretical value because of the hysteresis. When such a shift of the phase inversion to the high-frequency side is caused, the frequency at which the vibration amplitude of the driven member 16 is minimized because vibration from the second outer springs SP12 and vibration from the second inner springs SP22 cancel out each other may also be shifted to the high-frequency side (high-rotation side). In the light of this, the inventors closely investigated the effect of the hysteresis on the phase inversion of vibration due to resonance at the natural frequency on the low-frequency side in the damper device 10 and the damper device according to the comparative example.

The inventors first performed a simulation for a model of the damper device according to the comparative example in which the theoretical frequency fa′ (see the formula (18) given above) of the antiresonance point is caused to generally coincide with a frequency ftag of resonance due to vibration of the entire damper device and the drive shaft of the vehicle (resonance due to vibration generated between the drive member and the drive shaft) to verify variations in phase of vibration due to resonance at the natural frequency f₂₁′ on the low-frequency side. In FIG. 15, the simulation result for the damper device according to the comparative example is indicated by the broken line. It was revealed that, in the damper device according to the comparative example, as indicated in FIG. 15, a frequency f at which the phases of vibrations in the two torque transfer paths were shifted by 180 degrees from each other was shifted to the high-frequency side (high-rotation side) with respect to the frequency flag (an engine rotational speed corresponding thereto) of vibration to be damped as indicated by the broken line in the drawing. Thus, it is considered that the damper device according to the comparative example may not damp resonance due to vibration of the entire damper device and the drive shaft of the vehicle well.

The inventors further performed a simulation for a model of the damper device 10 in which the theoretical frequency fa (see the formula (6) given above) of the antiresonance point A is caused to generally coincide with the frequency flag (the same value as with the comparative example) of resonance due to vibration of the entire damper device 10 and the drive shaft of the vehicle to verify variations in phase of vibration due to resonance at the natural frequency f₂₁on the low-frequency side in the damper device 10. In FIG. 15, the simulation result for the damper device 10 is indicated by the solid line. As seen from the simulation results in FIG. 15, with the damper device 10 configured as discussed above, it is possible to reduce the effect of the hysteresis on the phase inversion of vibration due to resonance at the natural frequency f₂₁on the low-frequency side well compared to the damper device according to the comparative example.

That is, with the damper device 10 which includes the intermediate springs SPm, as discussed above, resonance at the natural frequency f₂₁on the low-frequency side, that is, resonance of the first intermediate member 12, can be easily shifted to the low-frequency side by adjusting the moments of inertia J₂₁and J₂₂of the first and second intermediate members 12 and 14. In the damper device 10, in addition, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22 meet the relations k₁₁<k₂₁and k₁₁/k₂₁≠k₁₂/k₂₂. Consequently, it is possible to transfer torque (a part of average torque) from the second intermediate member 14 to the first intermediate member 12 via the third torque transfer path P3 which includes the intermediate springs SPm. This reduces torque distribution to the first outer springs SP11 to reduce the spring constant k₁₁(rigidity reduction), and allows a friction force generated between the first outer springs SP11 and the rotary elements to be reduced because of a reduction in weight of the first outer springs SP11 due to the rigidity reduction. Thus, it is possible to reduce the hysteresis of the first outer springs SP11, and to immediately complete the phase inversion of vibration (make the gradient of phase variations steep) transferred from the second outer springs SP12 to the driven member 16 (vibration through the first torque transfer path P1) due to resonance at the natural frequency f₂₁, that is, resonance of the first intermediate member 12, as indicated by the thin solid line in FIG. 15. As a result, with the damper device 10, the effect of the hysteresis on the phase inversion can be reduced and, as indicated by the solid line in FIG. 15, the frequency fr at which the phase of vibration transferred from the second outer springs SP12 to the driven member 16 is shifted by 180 degrees with respect to the phase of vibration transferred from the second inner springs SP22 to the driven member 16 can be shifted to the low-frequency side (low-rotation side) with respect to the frequency ftag of vibration to be damped.

In the damper device 10, further, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22 meet the relations k₁₁/k₂₁<k₂/k₂₂and k₁₁<k₁₂<k₂₂<k₂₁. In the case where such relations are met, torque (a part of average torque) is transferred from the second intermediate member 14 to the first intermediate member 12 via the third torque transfer path P3 which includes the intermediate springs SPm, which increases torque transferred by the second outer springs SP12 which are provided between the first intermediate member 12 and the driven member 16. Meanwhile, in theory, the torque T which is input to the drive member 11 (sum of transfer torque of the first outer springs SP11 and transfer torque of the first inner springs SP21) and the sum of transfer torque of the second outer springs SP12 and transfer torque of the second inner springs SP22 are equal to each other. Thus, in the case where the relations k₁₁/k₂₁<k₁₂/k₂₂and k₁₁<k₁₂<k₂₂<k₂₁are met, the spring constant k₁₁of the first outer springs SP11 can be reduced (rigidity reduction) by further reducing torque distribution to the first outer springs SP11 and, further, the spring constant k₁₂of the second outer spring SP12 can also be reduced (rigidity reduction). Thus, with the damper device 10, it is possible to further reduce a friction force generated between the first and second outer springs SP11 and SP12 and the rotary elements, that is, the hysteresis, because of a weight reduction of the first and second outer springs SP11 and SP12 due to the rigidity reduction, and to shift resonance at the natural frequency f₂₁, that is, resonance of the first intermediate member 12, to the low-frequency side. As a result, as indicated by the thick solid line in FIG. 15, a shift of the frequency fr described above to the high-frequency side due to the hysteresis can be reduced well.

FIG. 16 illustrates the relationship among a torque distribution ratio γ₁of the first outer springs SP11 and the first inner springs SP21 to which torque is transferred from the drive member 11, a torque distribution ratio γ₂of the second outer springs SP12 and the second inner springs SP22 which transfer torque to the driven member 16, and the vibration damping performance of the damper device 10. The inventors also analyzed the relationship between the torque distribution ratios γ₁and γ₂and the vibration damping performance of the damper device 10 at the time when the torque T which was input to the drive member 11 was a predetermined value that is less than the torque T1 described above (when deflection of all of the springs SP11, SP12, SP21, SP22, and SPm was allowed). When torque that the first outer springs SP11 transfer from the drive member 11 to the first intermediate member 12 is defined as “T₁₁” and torque that the first inner springs SP21 transfer from the drive member 11 to the second intermediate member 14 is defined as “T₂₁”, the torque distribution ratio T1 is represented as γ₁=T₁₁/(T₁₁+T₂₁). When torque that the second outer springs SP12 transfer from the first intermediate member 12 to the driven member 16 is defined as “T₁₂” and torque that the second inner springs SP22 transfer from the second intermediate member 14 to the driven member 16 is defined as “T₂₂”, the torque distribution ratio γ₂is represented as γ₂=T₁₂/(T₁₂+T₂₂). In addition, as discussed above, the relation T=T₁₁+T₂₁=T₁₂+T₂₂is met in theory between the input torque T and the torques T₁₁, T₂₁, T₁₂, and T₂₁. In this analysis as well, as in FIG. 8 etc., the vibration damping performance of the damper device 10 was evaluated on the basis of the vibration amplitude (torque fluctuations) of the driven member 16.

As with the damper device 10, in the case where torque (a part of average torque) is transferred from the second intermediate member 14 to the first intermediate member 12 via the third torque transfer path P3 which includes the intermediate springs SPm, the torque distribution ratios γ₁and γ₂are included in a region X positioned on the upper side of a line segment that indicates γ₁=γ₂in FIG. 16 (excluding points on the line segment which indicates γ₁=γ₂). Such a region X is a region in which the relation γ₁<γ₂, that is, T₁₁/(T₁₁+T₂₁)<T₁₂/(T₁₂+T₂₂), is met. The inventors obtained through analysis a range in the region X in which the vibration damping performance was secured well while suppressing an increase in coil radius or axial length of the springs SP11, SP12, SP21, SP22, and SPm, that is, an increase in size of the damper device 10.

As a result of the analysis, it was revealed that the vibration damping performance was secured well while suppressing an increase in size of the damper device 10 in the case where the torque distribution ratios γ₁and γ₂were included in a region Y indicated in FIG. 16. The region Y is a region that meets γ₁<γ₂, 0.07≦γ₁=T₁₁/(T₁₁+T₂₁)≦0.28, and 0.12≦γ₂=T₁₂/(T₁₂+T₂₂)≦0.42. Furthermore, the analysis conducted by the inventors has revealed that the vibration damping performance of the damper device 10 may be further improved in the case where the torque distribution ratios γ₁and γ₂are included in a region Z in the region Y indicated in FIG. 16. The region Z is a region that generally meets γ₁<γ₂, 0.1≦γ₁=T₁₁/(T₁₁+T₂₁)≦0.25, and 0.13≦γ₂=T₁₂/(T₁₂+T₂₂)≦0.39. Thus, the damper device 10 is preferably configured to meet γ₁<γ₂, 0.07≦γ₁=T₁₁/(T₁₁+T₂₁)≦0.28, and 0.12≦γ₂=T₁₂/(T₁₂+T₂₂)≦0.42, more preferably γ₁<γ₂, 0.1≦γ₁=T₁₁/(T₁₁+T₂₁)≦0.25, and 0.13≦γ₂=T₁₂/(T₁₂+T₂₂)≦0.39.

In addition, when torque that the intermediate springs SPm transfer between the first and second intermediate members 12 and 14 is defined as “T_m”, γ₂−γ₁=T_m/(T₁₁+T₂₁)=T_m/(T₁₂+T₂₂) is met. Such a value (γ₂−γ₁) indicates the proportion of transfer torque of the intermediate springs SPm to the input torque T (torque output from the driven member 16). The analysis conducted by the inventors has revealed that the vibration damping performance may be secured well while suppressing an increase in size of the damper device 10 when 0<γ₂−γ₁≦0.35 is met. Since it is also considered that the relation T₁₁+T₂₁=T₁₂+T₂₂is not met to be exact because of a loss or the like, the damper device 10 may be configured to meet one of 0<γ₂−γ₁≦0.35 and 0<T_m/(T₁₂+T₂₂)≦0.35.

FIG. 17 illustrates an example of the relationship between the rotational speed of the engine EG and the vibration amplitude (torque fluctuations) of the driven member of the damper device 10 and the damper device according to the comparative example, from which the intermediate springs SPm have been omitted, with the hysteresis taken into consideration. In FIG. 17, the solid line indicates the simulation result for the vibration amplitude (torque fluctuations) of the driven member of the damper device 10 with the hysteresis taken into consideration, and the broken line indicates the simulation result for the vibration amplitude (torque fluctuations) of the driven member of the damper device according to the comparative example with the hysteresis taken into consideration. A model of the damper device 10 used in such simulation was built by determining various specifications so as to meet the relation k₁₁<k_m<k₁₂<k₂₂<k₂₁and the relations γ₁<γ₂, 0.07≦γ₁=T₁₁/(T₁₁+T₂₁)≦0.28, and 0.12≦γ₂=T₁₂/(T₁₂+T₂₂)≦0.42, and such that the theoretical frequency fa of the antiresonance point A generally coincided with the frequency flag of resonance due to vibration of the entire damper device 10 and the drive shaft of the vehicle discussed above. Meanwhile, a model of the damper device according to the comparative example used in the simulation was built by determining various specifications such that the theoretical frequency fa′ of the antiresonance point generally coincided with the frequency flag (the same value as with the damper device 10) of resonance due to vibration of the entire damper device and the drive shaft of the vehicle.

As indicated in FIG. 17, with the damper device 10, resonance at the natural frequency f₂₁on the low-frequency side which causes the antiresonance point A, that is, resonance of the first intermediate member 12, can be shifted to the lower-frequency side to be moved away from the antiresonance point A, compared to the damper device according to the comparative example. Thus, it is understood that the vibration damping performance of the damper device 10 can be improved extremely well, compared to the damper device according to the comparative example, by bringing the frequency fa of the antiresonance point A closer to the frequency flag of vibration (resonance) to be damped. As a result, with the starting device 1 which includes the damper device 10, it is possible to set the lock-up rotational speed Nlup of the lock-up clutch 8 to the lower-rotation side (e.g. a rotational speed that is lower than the rotational speed of the engine EG corresponding to the frequency flag), compared to the damper device according to the comparative example. That is, by selecting the spring constants k₁₁, k₁₂, k₂₁, k₂₂, and k_mso as to meet k₁₁<k_m<k₁₂<k₂₂<k₂₁, it is possible to improve the vibration damping performance of the damper device 10 extremely well by appropriately transferring torque from the second intermediate member 14 to the first intermediate member 12 via the intermediate springs SPm.

In the damper device 10 described above, the natural frequency of the second intermediate member 14 corresponding to the first and second inner springs SP21 and SP22, which are disposed on the radially inner side of the first and second outer springs SP11 and SP12, may be made lower than the natural frequency of the first intermediate member 12. That is, the natural frequency of the second intermediate member 14 may be determined from the formula (13) given above, and the natural frequency of the first intermediate member 12 may be determined from the formula (14) given above. In this case, further, the smaller one of the spring constants k₂₁and k₂₂of the first and second inner springs SP21 and SP22 is preferably smaller than the smaller one of the spring constants k₁₁and k₁₂of the first and second outer springs SP11 and SP12. That is, in this case, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂are preferably selected so as to meet k₂₁≠k₁₁and k₂₁/k₁₁≠k₂₂/k₁₂. More particularly, the spring constants k₁₁, k₁₂, k₂₁, k₂₂, and k_mare preferably selected so as to meet the relations k₂₁/k₁₁<k₂₂/k₁₂and k₂₁<k_m<k₂₂<k₁₂<k₁₁.

In the damper device 10 configured in this way, the first and second inner springs SP21 and SP22 corresponding to the second intermediate member 14, which has a lower natural frequency than that of the first intermediate member 12, are disposed on the radially inner side of the first and second outer springs SP11 and SP12 corresponding to the first intermediate member 12. Consequently, it is possible to increase the torsional angle (stroke) of the first and second outer springs SP11 and SP12 with a high rigidity, and the rigidity of the first and second outer springs SP11 and SP12 can be lowered while allowing transfer of large torque to the drive member 11. As a result, it is possible to reduce the equivalent rigidity keq of the damper device 10, and to shift resonance of the entire vibration system including the damper device 10, that is, resonance due to vibration of the entire damper device 10 and the drive shaft of the vehicle (resonance due to vibration generated between the drive member and the drive shaft), to the lower-rotation side (lower-frequency side). Thus, the vibration damping performance of the damper device 10 can be improved extremely well by bringing the frequency of the antiresonance point A described above closer to the frequency of resonance of the entire vibration system.

In the damper device 10 described above, in addition, the spring constant K₂₁of the first inner springs SP21 is larger than the spring constant K₂₂of the second inner springs SP22 (k₂₂<k₂₁). However, the disclosure is not limited thereto. That is, in order to make it easy to design the damper device 10, the specifications such as the spring constant K₂₁, the coil radius, and the axial length of the first inner springs SP21 may be the same as the specifications such as the spring constant K₂₂, the coil radius, and the axial length of the second inner springs SP22 (k₂₂=k₂₁).

In the damper device 10, further, the spring constant k_mof the intermediate springs SPm may be determined to be smaller than the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22. That is, as discussed above, the natural frequency f₂₁on the low-rotation side (low-frequency side) and the frequency fa of the antiresonance point A are lower as the synthetic spring constant k₅of the intermediate springs SPm is smaller (see FIG. 13). Thus, by making the spring constant (rigidity) k_mof the intermediate springs SPm smaller than the spring constants k₁₁, k₁₂, k₂₁, and k₂₂, the natural frequency f₂₁and the frequency fa can be made much smaller. Adopting such a configuration also makes it possible to set the start point of a rotational speed band in which one of vibration transferred from the second outer springs SP12 to the driven member 16 and vibration transferred from the second inner springs SP22 to the driven member 16 is used to cancel out at least a part of the other on the lower-rotation side. By setting the start point of such a rotational speed band on the low-rotation side, additionally, the rotational speed (frequency) at which the phase of vibration transferred from the second outer springs SP12 to the driven member 16 and the phase of vibration transferred from the second inner springs SP22 to the driven member 16 are shifted by 180 degrees from each other can also be set to the low-rotation side (low-frequency side). In this case, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22 preferably meet at least the relations k₁₁≠k₂₁and k₁₁/k₂₁≠k₁₂/k₂₂.

In the damper device 10, in addition, the spring constant k_mof the intermediate springs SPm may be determined to be larger than the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22. That is, as discussed above, the difference (fa−f₂₁) between the natural frequency f₂₁on the low-rotation side (low-frequency side) and the frequency fa of the antiresonance point A is larger as the synthetic spring constant k₅of the intermediate springs SPm is larger (see FIG. 13). Thus, by making the spring constant (rigidity) k_mof the intermediate springs SPm larger than the spring constants k₁₁, k₁₂, k₂₁, and k₂₂, it is possible to widen the rotational speed band in which one of vibration transferred from the second outer springs SP12 to the driven member 16 and vibration transferred from the second inner springs SP22 to the driven member 16 is used to cancel out at least a part of the other, that is, a range in which the vibration level of the driven member 16 may be lowered well, by increasing the difference from the difference (fa−f₂₁) between the natural frequency f₂₁and the frequency fa.

In this case, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22 are preferably adjusted such that the natural frequency f₂₁and the frequency fa of the antiresonance point A are further reduced and the difference (fa−f₂₁) therebetween is more increased. From the viewpoint of ease of setting the values of the spring constants k₁₁, k₁₂, k₂₁, and k₂₂for further reducing the natural frequency f₂₁and the frequency fa of the antiresonance point A, such a configuration is advantageously applied to a damper device for which maximum torque input to the drive member 11 is relatively small and the required equivalent rigidity keq is relatively low. In this case as well, the spring constants k₁₁, k₁₂, k₂₁, and k₂₂of the first and second outer springs SP11 and SP12 and the first and second inner springs SP21 and SP22 preferably meet the relations k₁₁≠k₂₁and k₁₁/k₂₁≠k₁₂/k₂₂.

Furthermore, the damper device 10 may further include at least one torque transfer path provided in parallel with the first and second torque transfer paths P1 and P2, for example, in addition to the first, second, and third torque transfer paths P1, P2, and P3. Moreover, at least one of the first and second torque transfer paths P1 and P2, for example, of the damper device 10 may be additionally provided with at least one set of an intermediate member and springs (elastic bodies).

In the starting device 1, in addition, in the case where slip control in which the actual slip speed (actual rotational speed difference) between the engine EG and the input shaft (drive member 11) of the transmission TM is caused to coincide with a target slip speed, the frequency fa of the antiresonance point A described above may be caused to coincide with a frequency fs of shudder generated when the slip control is executed, or may be set to a value that is close to the frequency fs of the shudder. Consequently, it is possible to reduce shudder generated when the slip control is executed. If the moment of inertia of the lock-up piston 80 and the drive member 11 which rotate together with each other is defined as “J_pd”, the frequency fs of the shudder can be represented as fs=½π·√(k_eq/J_pd) using the moment of inertia J_pdand the equivalent rigidity k_eqof the damper device 10.

As has been described above, the present disclosure provides a damper device (10) that has an input element (11) to which torque from an engine (EG) is transferred and an output element (16), including: a first intermediate element (12); a second intermediate element (14); a first elastic body (SP11) that transfers torque between the input element (11) and the first intermediate element (12); a second elastic body (SP12) that transfers torque between the first intermediate element (12) and the output element (16); a third elastic body (SP21) that transfers torque between the input element (11) and the second intermediate element (14); a fourth elastic body (SP22) that transfers torque between the second intermediate element (14) and the output element (16); and a fifth elastic body (SPm) that transfers torque between the first intermediate element (12) and the second intermediate element (14). In the damper device, the third and fourth elastic bodies (SP21, SP22) are disposed on a radially inner side with respect to the first and second elastic bodies (SP11, SP12); and the input element (11) includes a first input member (111) that has a first abutment portion (111c) abutting against an end portion of the first elastic body (SP11) in a circumferential direction and that is rotatably supported by a first support portion (71), and a second input member (112) that rotates together with the first input member (111), that has a second abutment portion (112c) abutting against an end portion of the third elastic body (SP21) on the radially inner side with respect to the first abutment portion (111c), and that is rotatably supported by a second support portion (72) provided at a different position from that of the first support portion (71).

The input element (11, 111b) may support the first intermediate element (12) in a radial direction.

The input element may include a third input member that rotates together with the first and second input members; and the second and third input members may support the third and fourth elastic bodies in a radial direction.

The first input member (11) may have an abutment portion (111c) that extends in an axial direction to abut against the end portion of the first elastic body (SP11) in the circumferential direction.

The first input member (111) may be fitted with the second input member with a backlash in a radial direction. Consequently, it is possible to rotate both the first and second input members together with each other while supporting (aligning) the first and second input members so as to be individually rotatable.

The damper device (10) may further include a power input member (80) which is rotatably supported by the first support portion (71) and to which torque from the engine (EG) is transferred; and the first input member (111) may be fixed to the power input member (80).

The second support portion (72) may be provided so as to be displaced from the first support portion (71) at least in an axial direction.

The fifth elastic body may be disposed side by side with the first and second elastic bodies along a circumferential direction. Consequently, it is possible to shorten the axial length of the damper device, and to secure the strokes of the first, second, and fifth elastic bodies well.

The input element (11) may further include a third input member (113) that has a third abutment portion (113c) abutting against the end portion of the third elastic body (SP21) and that is coupled so as to be arranged side by side with the second input member (112) in an axial direction; the second and third input members (112, 113) may support the third and fourth elastic bodies (SP21, SP22) such that the third and fourth elastic bodies (SP21, SP22) are arranged alternately along the circumferential direction; and the output element (16) may be disposed between the second and third input members (112, 113) in the axial direction, and have an abutment portion (16co) abutting against an end portion of the second elastic body (SP12) and an abutment portion (16ci) abutting against an end portion of the fourth elastic body (SP22). Consequently, it is possible to reduce a force (a force in the direction of moving the second and third input members apart from each other) applied from the third and fourth elastic bodies, which receive a centrifugal force during rotation of the input element etc., to the second and third input members to deform the second and third input members by suppressing an increase in distance between the second and third input members. As a result, it is possible to secure the strength, durability, etc. of a coupling portion between the second and third input members well while suppressing an increase in size of such a coupling portion and hence the entire damper device.

One (12) of the first and second intermediate elements may be coupled so as to rotate together with a turbine runner (5) that constitutes a fluid transmission apparatus together with a pump impeller (4). Consequently, the substantial moment of inertia of one of the first and second intermediate elements (the total moment of inertia) can be increased. Thus, it is possible to further reduce the lower one of the two natural frequencies of the damper device.

The first intermediate element (12) may include an elastic body support member (121) that is supported by the input element (11, 111) in a radial direction to support the first and second elastic bodies (SP11, SP12) such that the first and second elastic bodies (SP11, SP12) are arranged alternately along the circumferential direction and that has an abutment portion (121c) provided between the first and second elastic bodies (SP11, SP12) which are adjacent to each other so as to abut against end portions of such first and second elastic bodies (SP11, SP12), and a coupling member (122) that is coupled so as to rotate together with the turbine runner (5) and that has an abutment portion (122c) provided between the first and second elastic bodies (SP11, SP12) which are adjacent to each other so as to abut against the end portions of such first and second elastic bodies (SP11, SP12). Consequently, it is possible to couple the first intermediate element to both the first elastic body and the second elastic body, which are disposed on the radially outer side, and to couple the first intermediate element to the turbine runner while making the entire damper device compact. Additionally, by causing both the abutment portion of the elastic body support member and the abutment portion of the coupling member to abut against the end portions of the first and third elastic bodies, it is possible to smoothly expand and contract the first and third elastic bodies. A natural frequency of the first intermediate element (12) at a time when torque is transferred from the input element to the output element via all of the first to fifth elastic bodies may be lower than a natural frequency of the second intermediate element (14) at a time when torque is transferred from the input element to the output element via all of the first to fifth elastic bodies.

A lower one of a rigidity of the first elastic body (SP11) and a rigidity of the second elastic body (SP12) may be lower than a lower one of a rigidity of the third elastic body (SP21) and a rigidity of the fourth elastic body (SP22).

A natural frequency of the second intermediate element (14) at a time when torque is transferred from the input element to the output element via all of the first to fifth elastic bodies may be lower than a natural frequency of the first intermediate element (12) at a time when torque is transferred from the input element to the output element via all of the first to fifth elastic bodies.

A lower one of a rigidity of the third elastic body (SP21) and a rigidity of the fourth elastic body (SP22) may be lower than a lower one of a rigidity of the first elastic body (SP11) and a rigidity of the second elastic body (SP12).

The damper device (10) may be configured such that deflection of the first to fifth elastic bodies (SP11, SP12, SP21, SP22, SPm) is not restricted until torque (T) transferred to the input element (11) becomes equal to or more than a threshold (T1) determined in advance. Consequently, it is possible to improve the vibration damping performance of the damper device well when torque transferred to the input element is relatively small and the rotational speed of the input element is low.

The output element (16) may be functionally (directly or indirectly) coupled to an input shaft (IS) of a transmission (TM).

The disclosure according to the present disclosure is not limited to the embodiment described above in any way, and it is a matter of course that the disclosure may be modified in various ways without departing from the range of the extension of the present disclosure. Furthermore, the embodiment described above is merely a specific form of the disclosure described in the “SUMMARY” section, and does not limit the elements of the disclosure described in the “SUMMARY” section.

INDUSTRIAL APPLICABILITY

The disclosure according to the present disclosure can be utilized in the field of manufacture of damper devices or the like.

Number	Date	Country	Kind
2015-071610	Mar 2015	JP	national
2015-071793	Mar 2015	JP	national
2015-115845	Jun 2015	JP	national
2015-147598	Jul 2015	JP	national
2015-233742	Nov 2015	JP	national

DAMPER DEVICE

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