Patent Application
20100167868
The disclosure of Japanese Patent Application No. 2008-335125 filed on Dec. 26, 2008 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present invention relates to a friction type continuously variable transmission which has a friction member in contact with an input side friction wheel and an output side friction wheel with oil intervening therebetween and changes the contact position to steplessly shift the speed of rotation between an input shaft and an output shaft, relates preferably to a conical friction ring type continuously variable transmission in which conical friction wheels (cones) are disposed respectively on two shafts disposed in parallel so as to transmit rotation between the two shafts via a ring disposed to be movable in an axial direction, and relates particularly to a friction type continuously variable transmission including a pressing device which applies an axial force in an axial direction to a friction wheel such as a cone so as to obtain a traction force with a friction member such as a ring.
Conventionally, there has been known a conical friction ring type (cone ring type) continuously variable transmission which has a steel ring interposed in a form surrounding a primary cone between two friction wheels (primary cone, secondary cone) each of which being a conical shape, transmits motive power from the primary cone to the secondary cone via the ring, and changes the contact position between the ring and the two cones by moving the ring in an axial direction so as to perform stepless speed shifting.
As the pressing device of the conical friction ring type continuously variable transmission, there has been proposed one described in Published Japanese Translation of PCT Application No. JP-A-2006-513375. This pressing device (described as a press-on device in Published Japanese Translation of PCT Application No. JP-A-2006-513375) has, as a basic structure, a torque cam disposed between a secondary cone and a secondary shaft, applies to the secondary cone an axial force corresponding to torque in a relative rotational direction of the secondary cone and the secondary shaft, and retains a traction force between a primary cone supported unmovably in the axial direction and the secondary cone to which the axial force is applied and the ring for performing the above-described stepless speed shifting.
The above-described pressing device in which one torque cam is provided has difficulty in applying an appropriate axial force across the entire speed range with respect to the total load or a partial load of the continuously variable transmission. The pressing device in Published Japanese Translation of PCT Application No. JP-A-2006-513375 has a second press-on device disposed in addition to a first press-on device unit with the torque cam in which a second axial force by the second press-on device acts in addition to or subtracting from a first axial force by the first press-on device, so as to have more appropriate axial force characteristics. Various embodiments are described as the second press-on device. For example, there is one using hydraulic pressures in which the second axial force acts to cancel out the first axial force to thereby obtain a two-stage axial force characteristic bending in middle, so as to prevent energy loss and decrease in device operating life caused by a unnecessarily large load acting on the continuously variable transmission because the linear first axial force by the torque cam is too large at a portion where output torque is large.
There is proposed an embodiment using a torque cam as the second press-on device (see
In the pressing device (press-on device) in the above-described Published Japanese Translation of PCT Application No. JP-A-2006-513375, since the two torque cams act in series in directions to cancel out each other, setting of axial forces by the torque cams is complicated, and it is difficult to obtain appropriate axial force characteristics. Further, end cam plates (press-on plates 114, 115) on outside of both the two torque cams disposed in series are spline-coupled to be movable in an axial direction, and an intermediate cam plate (press-on plate 116) located between both the torque cams and having cams formed on both side ends are spline-coupled to the secondary cone to be movable in the axial direction. Large relative rotation occurs between the end cam plates and the intermediate cam plate, and a thrust bearing which allows relative rotation is needed between one of the end cam plates (press-on plate 115) and the secondary cone. Accordingly, the number of parts increases and the structure becomes complicated, thereby causing increase in cost and size of the device.
Therefore, it is an object of the present invention to provide a friction type continuously variable transmission having a pressing device in which two torque cams are disposed in parallel and capable of solving the above-described problems.
The present invention resides in a friction type continuously variable transmission including an input side friction wheel drive-coupled to an input shaft, an output side friction wheel drive-coupled to an output shaft, and a friction member pressure-contacting with the input side friction wheel and the output side friction wheel and transmitting motive power with both the friction wheels, and in the friction type continuously variable transmission, a contact position of the friction member with the input side friction wheel and the output side friction wheel is changed to steplessly shift speed of rotation between the input shaft and the output shaft. The friction type continuously variable transmission includes: a pressing device which is disposed between the input shaft and the input side friction wheel or between the output side friction wheel and the output shaft and applies an axial force to pressure-contact the input side friction wheel and the output side friction wheel with the friction member. In the friction type continuously variable transmission, the pressing device has a first torque cam and a second torque cam which are. disposed in parallel with a transmission path of torque, the first torque cam passes transfer torque in a region where the transfer torque is smaller than a predetermined value so as to generate an axial force corresponding to the transfer torque, and the second torque cam passes transfer torque in a region where the transfer torque is larger than the predetermined value so as to generate an axial force corresponding to the transfer torque.
The pressing device is disposed between the output side friction wheel and the output shaft.
In the pressing device, a spring is disposed in series in an axial force direction of the first torque cam. The first torque cam generates an axial force corresponding to transfer torque transmitted via the first torque cam in a state exceeding an axial force by a preload of the spring, and the second torque cam has a predetermined play and generates an axial force based on the first torque cam within the predetermined play, and running out of the predetermined play causes transmission of torque via the second torque cam to generate an axial force corresponding to increase of the transfer torque.
A cam angle of the second torque cam is set larger than a cam angle of the first torque cam.
The friction type continuously variable transmission further includes an adjusting unit that adjusts an axial length of the spring, and the adjusting unit adjusts the predetermined value by which the second torque cam generates an axial force.
The pressing device includes: a flange part fixed with respect to the output shaft; and a spring unit having a pressure receiving member and a spring, the pressure receiving member being disposed between the output side friction wheel and the output shaft to be relatively unrotatable and movable in an axial direction with respect to the output side friction wheel or the output shaft. The first torque cam has a plurality of first balls disposed in a first facing portion facing between the pressure receiving member of the spring unit and the flange part or the output side friction wheel which relatively rotates with respect to the spring unit, and applies an axial force to the output side friction wheel while moving the pressure receiving member in the axial direction based on an axial force exceeding an axial force by a preload of the spring, and the second torque cam has a plurality of second balls disposed in a second facing portion facing between the output side friction wheel and the flange part and a predetermined play to float the second balls in the second facing portion, and when the predetermined play runs out in the second facing portion, transfer torque is transmitted via the second torque cam to apply an axial force corresponding to the transfer torque to the output side friction wheel.
In the pressing device, the spring unit is disposed to be relatively unrotatable and movable in the axial direction with respect to the output side friction wheel, the first torque cam includes a plurality of first end face pairs each formed in the first facing portion where the pressure receiving member and the flange part face each other, and the plurality of first balls disposed respectively between the plurality of first end face pairs, and the second torque cam includes a plurality of second end face pairs each formed in the second facing portion where the output side friction wheel and the flange part face each other, and the plurality of second balls disposed respectively between the plurality of second end face pairs.
In the pressing device, the spring unit is disposed to be relatively unrotatable and movable in the axial direction with respect to the output shaft, the first torque cam includes a plurality of first end face pairs each formed in the first facing portion where the pressure receiving member and the output side friction wheel face each other, and the plurality of first balls disposed respectively between the plurality of first end face pairs, and the second torque cam includes a plurality of second end face pairs each formed in the second facing portion where the output side friction wheel and the flange part face each other, and the plurality of second balls disposed respectively between the plurality of second end face pairs.
The spring, first end faces of the pressure receiving member, the first balls, and first end faces of the flange part are disposed in series in the axial direction from one side in the axial direction of the output side friction wheel, and second end face pairs of the output side friction wheel and the flange part are formed on a more outer peripheral side than first end face pairs of the pressure receiving member and the flange part.
The spring, first end faces of the pressure receiving member and second end faces of the output side friction wheel, the first balls and the second balls, and the first end faces and the second end faces of the flange part are disposed in series in the axial direction from one side in the axial direction of the output side friction wheel, a plurality of recessed and projecting portions are formed in an inner peripheral face of the output side friction wheel and a plurality of projecting portions are formed in the pressure receiving member to fit in the plurality of recessed portions of the output side friction wheel, and the first end face pairs are formed in the plurality of projecting portions of the pressure receiving member and the flange part and the second end face pairs are formed in the plurality of projecting portions of the output side friction wheel and the flange part.
The input side friction wheel and the output side friction wheel are conical friction wheels which are drive-coupled respectively to the input shaft and the output shaft disposed in parallel and are disposed so that large diameter portions and small diameter portions of the conical friction wheels are reverse from each other in an axial direction, and the friction member is a ring sandwiched and pressed by opposing inclined faces of both the conical friction wheels and is movable in the axial direction.
It should be noted that the reference numerals in parentheses above are for comparison with the drawings and for convenience in facilitating understanding of the invention, and do not affect the structures in claims by any means.
According to a first aspect of the present invention, in the pressing device, the two torque cams are used to mechanically generate an axial force corresponding to transfer torque, and energy consumption is lower as compared to a pressing device using hydraulic pressure. The two torque cams are disposed in parallel with the transmission path. In a region where the transfer torque is smaller than a predetermined value, torque is transmitted wholly via the first torque cam. In a region where the transfer torque is larger than the predetermined value, the transfer torque is shared by the second torque cam. Since the first and second torque cams thus function in the transfer torque regions different from each other to generate an axial force, an axial force required in the friction type continuously variable transmission can be set appropriately corresponding to each speed range and each load torque, and this enables secure and highly reliable stepless speed shifting in the friction type continuously variable transmission. Further, the pressing device does not apply an excessive axial force, thereby reducing energy loss during motive power transmission and improving transmission efficiency. This enables to extend the operating life of the friction type continuously variable transmission, and allows size reduction and weight reduction of parts such as a bearing and a case retaining an axial force, thereby improving compactness.
According to a second aspect of the present invention, in the pressing device, the first and second torque cams generate an axial force corresponding to output torque in each region, and thus a required axial force can be applied neither excessively nor insufficiently across all speed change ratios from the highest speed (O/D) side to the lowest speed (U/D) side of the friction type continuously variable transmission.
According to a third aspect of the present invention, a spring is disposed in series in an axial force direction with the first torque cam. Thus, when a preload of the spring is larger than the axial force of the first torque cam, the axial force based on the preload of the spring is obtained, and torque transmission in a low torque region (first stage) can be secured. Further, the second torque cam has a predetermined play, and operation of the second torque cam can be switched easily and reliably with the predetermined play. For example, it is possible to appropriately set an axial force generation region (second stage) by the first torque cam with a relatively steep gradient adapted to the highest speed side of a partial load, and an axial force generation region (third stage) by the second torque with a relatively gentle gradient adapted to a required axial force at each speed change ratio under a total load.
According to a fourth aspect of the present invention, the cam angle of the first torque cam is smaller than the cam angle of the second torque cam. Thus, while compressing the spring disposed in series with the first torque cam, the first torque cam relatively rotates to generate an axial force. When the predetermined play of the second torque cam runs out, the second torque cam with a small amount of movement in the axial direction with respect to the relative rotation functions entirely to generate an axial force, and the functioning states of the first and second torque cams can be switched easily and reliably at a predetermined value of transfer torque. At this time, the first torque cam generates an axial force by a relatively large gradient with respect to transfer torque with the relatively small cam angle, and the second torque cam generates an axial force by a relatively small gradient with respect to transfer torque with the relatively large cam angle. Thus, an axial force characteristic complying with the axial forces required in the friction type continuously variable transmission can be obtained.
According to a fifth aspect of the present invention, by the adjusting unit such as a shim for adjusting the axial length of the spring, a switching position at which the second torque cam takes a share of torque transmission can be set easily and reliably, and output torque and an axial force when this switching occurs can be set appropriately. An appropriate axial force characteristic that is neither excessive nor insufficient can be easily set under a partial load and the total load and across an entire speed range.
According to a sixth aspect of the present invention, the flange part serves also as a member to which axial forces of the first torque cam and the second torque cam are applied, and the second torque cam applies the axial force of the second stage directly from the flange part to the output side friction wheel. Accordingly, the second torque cam can be disposed on the outer peripheral side of the first torque cam, and members to be disposed in series in the axial direction can be decreased, thereby achieving compactness in the axial direction. Also a member to couple the first torque cam and the second torque cam can be omitted, and this allows reduction of the number of parts.
Further, relative rotation of the shaft and the flange part and the output side friction wheel can only be relative rotation occurring via the first torque cam and the second torque cam. This eliminates the need of disposing bearings, and allows reduction of the number of parts.
According to a seventh aspect of the present invention, in the pressing device, the spring unit is disposed to be relatively unrotatable and movable in the axial direction with respect to the output side friction wheel. The first torque cam includes a plurality of first end face pairs each formed in the first facing portion where the pressure receiving member and the flange part face each other, and the plurality of first balls disposed respectively between the plurality of first end face pairs. The second torque cam includes a plurality of second end face pairs each formed in the second facing portion where the output side friction wheel and the flange part face each other, and the plurality of second balls disposed respectively between the plurality of second end face pairs. Thus a structure in which no relative rotation occurs except in the first torque cam and the second torque cam can be achieved.
According to an eight aspect of the present invention, in the pressing device, the spring unit is disposed to be relatively unrotatable and movable in the axial direction with respect to the shaft. The first torque cam includes a plurality of first end face pairs each formed in the first facing portion where the pressure receiving member and the output side friction wheel face each other, and the plurality of first balls disposed respectively between the plurality of first end face pairs. The second torque cam includes a plurality of second end face pairs each formed in the second facing portion where the output side friction wheel and the flange part face each other, and the plurality of second balls disposed respectively between the plurality of second end face pairs. Thus a structure in which no relative rotation occurs except in the first torque cam and the second torque cam can be achieved.
According to a ninth aspect of the present invention, second end face pairs of the output side friction wheel and the flange part are formed on a more outer peripheral side than first end face pairs of the pressure receiving member and the flange part. Thus, the second torque cam can be disposed on the more outer peripheral side than the first torque cam. This allows reduction of members to be disposed in series in the axial direction, thereby achieving compactness in the axial direction.
According to a tenth aspect of the present invention, the first end face pairs are formed in the plurality of projecting portions of the pressure receiving member and the flange part and the second end face pairs are formed in the plurality of projecting portions of the output side friction wheel and the flange part. Thus, the first torque cam and the second torque cam can be disposed alternately in the circumferential direction, thereby achieving compactness in the axial direction and moreover achieving compactness in the radial direction.
According to an eleventh aspect of the present invention, a conical friction ring (cone ring) type continuously variable transmission, which includes the conical friction wheels and the ring sandwiched between the opposing inclined faces of the conical friction wheels, is applied as the friction type continuously variable transmission. Thus, with the pressing device retaining a traction force between the ring and the conical friction wheels, precise and reliable stepless speed shifting can be performed by a quick response, and therefore it is optimum as a transmission for automobile.
A continuously variable transmission U mounted on a vehicle such as an automobile includes, as shown in
Motive power generated in an engine 30 is transmitted to a primary shaft (input shaft) 4 of the conical friction ring type continuously variable transmission 1 via the starting device 31 and the forward-reverse switching device 32 disposed downstream of the starting device 31 on a power transmission path, steplessly shifted in speed by the conical friction ring type continuously variable transmission 1, and output to a secondary shaft (output shaft) 11. The motive power is further transmitted to the differential 33 by a secondary gear 36 provided on the secondary shaft 11 and a mount gear 34 meshing therewith, and output to left and right driving wheels 35, 35.
Note that the continuously variable transmission U is presented as an example to which the conical friction ring type continuously variable transmission 1 is applied, and the present invention is not limited to this and may be applied to other devices such as a hybrid driving device having an engine and a motor as drive sources. Further, the conical friction ring type continuously variable transmission is presented representatively as an example of the friction type continuously variable transmission, and may be applied to any friction type continuously variable transmission which has a friction member in contact with an input side friction wheel and an output side friction wheel with oil intervening therebetween and changes the contact position to steplessly shift the speed of rotation between an input shaft and an output shaft, such as ring cone type continuously variable transmission in which a ring is disposed surrounding both the conical friction wheels and toroidal type continuously variable transmission. Further, this friction type continuously variable transmission U is partially immersed in traction oil. The traction oil is supplied between the contact portions by scooping up or the like, and motive power is transmitted via a shearing force of the oil.
The conical friction ring type continuously variable transmission 1 is structured from a primary cone (conical friction wheel) 2 as an input side friction wheel, a secondary cone (conical friction wheel) 10 as an output side friction wheel, a ring 3 as a friction member interposed between the primary cone 2 and the secondary cone 10, and a pressing device 12 including a spring unit 40, a first torque cam 15, and a second torque cam 20.
The primary cone 2 is coupled integrally to the primary shaft (input shaft) 4 coupled to the forward-backward switching device 32 and is supported rotatably on the case 5, and has a conical shape having a constant inclination angle. Further, surrounding an outer periphery of the primary cone 2, the ring 3 made of steel is disposed between the primary cone and the secondary cone 10.
The secondary cone 10 has a conical hollow shape having a same inclination angle as that of the primary cone 2, is inserted with the secondary shaft 11 (output shaft) provided in parallel with the primary shaft 4 in a direction axially opposite to the primary cone 2, and is supported rotatably on the case 5 by bearings 37, 38. The pressing device 12 according to this first embodiment is interposed between the secondary cone 10 and the secondary shaft 11.
The pressing device 12 is structured from, as shown in
The flange part 19 is a member formed in a stepped flange shape, disposed to be relatively unrotatable with the secondary shaft 11 by a spline, and restricted from moving in an axial direction (X2 direction) with respect to the secondary shaft 11 by a step portion. That is, the flange part 19 receiving a force in a direction (X2 direction) to depart from the secondary cone 10 by the first and second torque cams 15, 20, which will be described in detail later, is fixed with respect to the secondary shaft 11. Further, the secondary shaft 11 is supported integrally on the case 5 by a conical roller bearing (see
The pressure receiving member 14 of the spring unit 40 is disposed on an inner peripheral face of a tip side (on the X1 direction side) of the secondary cone 10 to be relatively unrotatable and movable in the axial direction with respect to the secondary cone 10 by a spline. Further, the spring 13 of the spring unit 40 is formed of disk springs arranged in an axial direction (X1-X2 direction), and is pressured between the secondary cone 10 and the pressure receiving member 14. In short, the secondary cone 10, the pressure receiving member 14, and the spring 13 are structured to rotate integrally, which eliminates the need of bearings disposed between these members. In addition, it is desired that the spring 13 is a disk spring. For example, the spring 13 may be a coil spring, and in other words, the present invention may be applied with any spring as long as the spring is capable of applying a preload to the secondary cone 10.
The first torque cam 15 is structured from a plurality of first end cam pairs (first end face pairs) 17 each formed in a first facing portion 16 where the pressure receiving member 14 and the flange part 19 face each other, and a plurality of first balls 18 disposed respectively between the plurality of first end cam pairs 17. The first end cam pairs 17 are structured from wavy end cams (first end faces) 14a formed in an end face on the X2 direction side of the pressure receiving member 14 and wavy end cams (first end faces) 19a formed in a portion facing the pressure receiving member 14 on an end face on the X1 direction side of the flange part 19. In short, the spring 13, the end cams 14a of the pressure receiving member 14, the first balls 18, and the end cams 19a of the flange part 19 are disposed in series in the axial direction from an inner peripheral tip side (X1 direction side) of the secondary cone 10.
The first torque cam 15 having the plurality of first balls 18 disposed and interposed between the plurality of first end cam pairs 17 is structured such that one member moves relative to the other member in a direction to depart therefrom along the axial direction by relative rotation of the pressure receiving member 14 and the flange part 19. That is, it is structured such that the movement in the X2 direction of the flange part 19 is restricted as described above, and the pressure receiving member 14 moves toward the X1 direction side to compress the spring 13.
The second torque cam 20 is structured from a plurality of second end cam pairs (second end face pairs) 22 each formed in a second facing portion 21 where the secondary cone 10 and the flange part 19 face each other, and a plurality of second balls 23 disposed respectively between the plurality of second end cam pairs 22. The second end cam pairs 22 are formed of a long groove shape extending in a circumferential direction, and at a predetermined rotation amount of the cam pairs 22, there is formed a predetermined play l (see
The second torque cam 20 having the plurality of second balls 23 disposed and interposed between the plurality of second end cam pairs 22 is structured such that one member moves relative to the other member in a direction to depart therefrom along the axial direction by relative rotation beyond the predetermined play of the secondary cone 10 and the flange part 19. That is, it is structured such that the movement in the X2 direction of the flange part 19 is restricted as described above, and the secondary cone 10 is pressed toward the X1 direction side.
As shown in
Moreover, the flange part 19 is formed with a step having a projecting cross-sectional shape, and this projecting portion is disposed in a direction in which a radial dimension of the secondary cone 10 becomes small (X1 direction). Thus, the flange part can be fitted with the conical shape of the secondary cone 10, thereby achieving compactness in the axial direction.
In the pressing device 12 structured as above, first the spring 13 energizes the secondary cone 10 in the X1 direction side constantly (specifically, even during non-operation in which motive power transmission by the conical friction ring type continuously variable transmission 1 is not performed) with respect to the secondary shaft 11 fixed in the axial direction, thereby acting as a preload of axial force that presses (pressure-contacts) the ring 3 against the primary cone 2 and the secondary cone 10 (first stage; see
Next, in the pressing device 12, when brought into operation in which torque is transmitted from the secondary cone 10 to the secondary shaft 11, the first torque cam 15 relatively rotates corresponding to (complying) load torque acting on the secondary shaft 11. Based on the relative rotation of the first torque cam 15, with respect to the secondary shaft 11 (the flange part 19) fixed in the axial direction the secondary cone 10 (the pressure receiving member 14) is applied an axial force in the X1 direction that has a large axial force increasing rate with respect to the load torque (second stage; see
At this time, the torque transmitted from the primary cone 2 is transmitted to the secondary shaft 11 via the secondary cone 10, the pressure receiving member 14, the first torque cam 15, and the flange part 19, as shown by a thick line denoted by a reference letter L in
Then, in the pressing device 12, when torque larger than that in the second stage is transmitted and the secondary cone 10 and the secondary shaft 11 (the flange part 19) rotate relatively beyond the play of the second torque cam 20, a cam portion of the second torque cam 20 operates corresponding to load torque acting on the secondary shaft 11. Based on the relative rotation of the second torque cam 20, with respect to the secondary shaft 11 (the flange part 19) fixed in the axial direction, the secondary cone 10 is applied an axial force in the X1 direction with a smaller increasing rate than that of the axial force in the second stage (third stage; see
Thus, the axial force in the X1 direction acting on the secondary cone 10 by the spring 13, the first torque cam 15, and the second torque cam 20 acts on the primary cone 2 restricted from moving in the axial direction as a sandwiching pressure to press the ring 3 against both the cones 2, 10 to apply a friction force required for torque transmission between the ring 3 and both the cones 2, 10 in the traction oil, and motive power is thereby transmitted between both the cones 2, 10. Further, the axial force applied by the pressing device 12 has the three stages of first stage, second stage, and third stage as shown in
Although the above description describes positive torque transmitted from the secondary cone 10 to the secondary shaft 11, note that an axial force in the X1 direction is generated similarly also by reverse torque (reverse drive) transmitted from the secondary shaft 11 to the secondary cone 10 due to engine braking or the like, since the end cams of the first and second end cam pairs 17, 22 are wavy shaped.
As described above, in the conical friction ring type continuously variable transmission 1 according to the first embodiment, the flange part 19 serves also as a member to which axial forces of the first torque cam 15 and the second torque cam 20 are applied, and the second torque cam 20 applies the axial force of the third stage directly from the flange part 19 to the secondary cone 10. Accordingly, the second torque cam 20 can be disposed on the outer peripheral side of the first torque cam 15, and members to be disposed in series in the axial direction can be reduced, thereby achieving compactness in the axial direction. Also a member to couple the first torque cam 15 and the second torque cam 20 can be omitted, and this allows reduction of the number of parts.
100661 Further, the relative rotation of the secondary shaft 11 and the flange part 19 and the secondary cone 10 can only be the relative rotation occurring via the first torque cam 15 and the second torque cam 20. This eliminates the need of disposing bearings, and allows reduction of the number of parts.
Further, since the second end cam pairs 22 of the secondary cone 10 and the flange part 19 are formed on the more outer peripheral side than the first end cam pairs 17 of the pressure receiving member 14 and the flange part 19, the second torque cam 20 can be disposed on the more outer peripheral side than the first torque cam 15. This allows reduction of members to be disposed in series in the axial direction, thereby achieving compactness in the axial direction.
Next, a second embodiment made by partially changing the first embodiment will be described with reference to
A conical friction ring type continuously variable transmission 1 according to the second embodiment is structured by providing the above-described conical friction ring type continuously variable transmission 1 with a pressing device 112, as shown in
The pressing device 112 is structured from, as shown in
The first torque cam 115 is structured from a plurality of first end cam pairs (first end face pairs) 117 each formed in a first facing portion 116 where the pressure receiving member 114 and the flange part 119 face each other, and a plurality of first balls 118 disposed respectively between the plurality of first end cam pairs 117. The first end cam pairs 117 are structured from wavy end cams (first end faces) 114a formed in an end face on the X2 direction side of the pressure receiving member 114 having a plurality of projecting portions 114c formed in a radial form to fit in recessed portions 110c among a plurality of recessed and projecting portions 110c, 110d formed in an inner peripheral face of the secondary cone 110 and wavy end cams (first end faces) 119a formed in a portion facing the plurality of projecting portions 114c of the pressure receiving member 114 on an end face on the X1 direction side of the flange part 119. In short, the spring 13, the end cams 114a of the pressure receiving member 114, the first balls 118, and the end cams 119a of the flange part 119 are disposed in series in the axial direction from the inner peripheral tip side (X1 direction side) of the secondary cone 110.
The first torque cam 115 having the plurality of first balls 118 disposed and interposed between the plurality of first end cam pairs 117 is structured such that one member moves relative to the other member in a direction to depart therefrom along the axial direction by relative rotation of the pressure receiving member 114 and the flange part 119. That is, it is structured such that the movement in the X2 direction of the flange part 119 is restricted as described above, and the pressure receiving member 114 moves toward the X1 direction side to compress the spring 13.
The second torque cam 120 is structured from a plurality of second end cam pairs (second end face pairs) 122 each formed in a second facing portion 121 where the secondary cone 110 and the flange part 119 face each other, and a plurality of second balls 123 disposed respectively between the plurality of second end cam pairs 122. The second end cam pairs 122 are structured from wavy end cams 110a formed in an end face of the projecting portions 110d projecting in an inner diameter direction to face the flange part 119 among the plurality of recessed and projecting portions 110c, 110d, which are formed in the inner peripheral face of the secondary cone 110 such that the projecting portions 114c of the pressure receiving member 114 formed in the radial form engage with the recessed portions 110c. The second end cam pairs 122 are also structured from wavy end cams (second end face) 119b formed in a portion facing the end cams 110a of the secondary cone 110 on an end face on the X1 direction side of the flange part 119. In short, the plurality of second end cam pairs 122 of the second torque cam 120 and the plurality of first end cam pairs 117 of the first torque cam 115 are disposed alternately in a circumference direction, and hence can be structured with a radial dimension smaller than that of the pressing device 12 according to the first embodiment.
The second torque cam 120 having the plurality of second balls 123 disposed and interposed between the plurality of second end cam pairs 122 is structured such that one member moves relative to the other member in a direction to depart therefrom along the axial direction by relative rotation of the secondary cone 110 and the flange part 119. That is, it is structured such that the movement in the X2 direction of the flange part 119 is restricted as described above, and the secondary cone 110 is pressed toward the X1 direction side.
The pressing device 112 structured as above operates to apply axial forces of three stages of first stage, second stage, and third stage similarly to the operation of the pressing device 12 according to the first embodiment, as shown in
As described above, in the conical friction ring type continuously variable transmission 1 according to the second embodiment, the first end cam pairs 117 are formed in the plurality of projecting portions (projecting in an outer diameter direction) of the pressure receiving member 114 and the flange part 119, and the second end cam pairs 122 are formed in the plurality of projecting portions (projecting in the inner diameter direction) of the secondary cone 110 and the flange part 119. Thus, the first torque cam 115 and the second torque cam 120 can be disposed alternately in the circumferential direction, thereby achieving compactness in the axial direction and moreover achieving compactness in the radial direction.
The structures, operations and effects of those other than the above-described parts are similar to those of the first embodiment, and thus descriptions thereof are omitted.
Next, a third embodiment made by partially changing the first embodiment will be described with
A conical friction ring type continuously variable transmission 1 according to the third embodiment is structured by providing the above-described conical friction ring type continuously variable transmission 1 with a pressing device 212, as shown in
The pressing device 212 is structured from, as shown in
The first torque cam 215 is structured from a plurality of first end cam pairs (first end face pairs) 217 each formed in a first facing portion 216 where the secondary cone 210 and the pressure receiving member 214 face each other, and a plurality of first balls 218 disposed respectively between the plurality of first end cam pairs 217. The first end cam pairs 217 are structured from wavy end cams (first end faces) 210a formed on an inner peripheral side of the secondary cone 210 and formed in an end face directed in the X2 direction, and wavy end cams (first end faces) 214a formed in an end face on the X1 direction side of the pressure receiving member 214. In short, the end cams 210a of the secondary cone 210, the first balls 218, the end cams 214a of the pressure receiving member 214, and the spring 13 are disposed in series in the axial direction from the inner peripheral tip side (X1 direction side) of the secondary cone 210.
The first torque cam 215 having the plurality of first balls 218 disposed and interposed between the plurality of first end cam pairs 217 is structured such that one member moves relative to the other member in a direction to depart therefrom along the axial direction by relative rotation of the secondary cone 210 and the pressure receiving member 214. That is, it is structured such that the movement in the X2 direction of the flange part 219 is restricted as described above, and a force acts on the pressure receiving member 214 toward the X2 direction side so as to compress the spring 13.
The second torque cam 220 is structured from a plurality of second end cam pairs (second end face pairs) 222 each formed in a second facing portion 221 where the secondary cone 210 and the flange part 219 face each other, and a plurality of second balls 223 disposed respectively between the plurality of second end cam pairs 222. The second end cam pairs 222 are structured from wavy end cams 210b formed in an end face of the secondary cone 210 facing the flange part 219, and wavy end cams 219a formed in a portion facing the secondary cone 210 on an end face on the XI direction side of the flange part 219.
The second torque cam 220 having the plurality of second balls 223 disposed and interposed between the plurality of second end cam pairs 222 is structured such that one member moves relative to the other member in a direction to depart therefrom along the axial direction by relative rotation of the secondary cone 210 and the flange part 219. That is, it is structured such that the movement in the X2 direction of the flange part 219 is restricted as described above, and the secondary cone 210 is pressed toward the X1 direction side.
The pressing device 212 structured as above operates to apply axial forces of three stages of first stage, second stage, and third stage similarly to the operation of the pressing device 12 according to the first embodiment, as shown in
The structures, operations and effects of those other than the above-described parts are similar to those of the first embodiment, and thus descriptions thereof are omitted.
Next, operations of the pressing device according to the present invention will be described with reference to
Next, in the second stage shown in
Next, the third stage will be described based on
At this time, a cam angle δ of the end cams of the second torque cam 20 is set larger than a cam angle γ of the end cams of the first torque cam 15. Thus, a relative rotation amount of the secondary cone 10 with respect to the flange part 19 based on output torque is smaller on the second torque cam 20 as compared to the first torque cam 15, and the torque transmitted from the secondary cone 10 to the flange part (secondary shaft) 19 is transmitted wholly via the second torque cam 20. Therefore, the first torque cam 15 is at a compressing position compressing the spring 13 by A-X, and is retained in a state generating an axial force F2 corresponding to output torque b, and the second torque cam 20 generates an axial force increasing corresponding to the output torque by a gradient β in addition to the axial force F2 formed of a constant value. Since the second torque cam 20 has the cam angle δ larger than the cam angle γ of the first torque cam 15, increase of an axial force with respect to the output torque is small due to the inclined plane principle, and the third stage has a gentler gradient as compared to the second stage (β<α).
Next, operations of applying axial force characteristics of the pressing device to the conical friction ring type continuously variable transmission will be described with reference to
When a total load acts on the conical friction ring type continuously variable transmission 1 and maximum torque is transmitted from the input shaft 4 to the output shaft 11, that is, the engine is operated at full throttle and transmits the torque to the driving wheels, an axial force generated by the pressing device 12 corresponding to output torque is as shown by a required axial force line A under total load. The required torque axial force line A under total load (maximum torque) shows an axial force that is necessary and sufficient for applying a friction force that does not cause slipping between both the primary and secondary cones 2, 10 and the ring 3 when transmitting the maximum torque. During underdrive (deceleration) U/D, that is, the ring 3 is on the right side of
The required axial force line A under total load sets an axial force required for motive power transmission at each speed change ratio when transmitting the maximum torque in the conical friction ring type continuously variable transmission 1. O/D with smallest output torque and axial force in the third stage of the present invention shown in
It is rational that a required axial force line A for maximum torque by two torque cams shown in
When transfer torque from the input shaft 4 to the output shaft 11 is a partial load, an axial force line required for transmitting partial torque corresponding to the partial load is shown as B1, B2, B3, B4 in
The conical friction ring type continuously variable transmission 1 is under the environment of the traction oil, through which motive power is transmitted via traction transmission with an oil film of the traction oil intervening between the ring and both the conical friction wheels (cones). The axial force characteristic (line) A of the third stage is set based on the gradient β connecting the point F2 of the axial force required for traction transmission to transmit maximum torque in a state that rotation transmitted from the input side friction wheel to the output side friction wheel is set to a highest speed (O/D) side, and the point F3 of the axial force required for traction transmission to transmit maximum torque in a state that the rotation is set to a lowest speed (U/D) side. Further, the axial force characteristic (line) C of the second stage is set based on the gradient a connecting the point of the axial force 0 at which output torque is 0 and the point F2 of the axial force required for the traction transmission to transmit maximum torque in a state that the rotation is set to the highest speed (O/D) side.
Then the constant axial force F1 by the spring preload in the first stage is set to an axial force larger than a (solidification) pressure (glass transition pressure) at which the oil film of the traction oil changes from a viscous characteristic of liquid to an elastic characteristic by solidification between the ring and both the conical friction wheels.
The characteristic formed by one torque cam shown in
The characteristic formed by two torque cams shown in
By the present invention shown in
The constant axial force in the first stage is set lower than the axial force (axial force when transmitting maximum torque) A2 by the linear function shown in
Next, the spring 13 used in the pressing device will be described with reference to
Accordingly, the required load H is set on the characteristic G during load decrease, and a load V on the characteristic E during load increase is set so as to correspond to the deflection d corresponding to the required load, and the spring 13 is assembled to have the load V. Thus, the axial force required in the first stage is obtained even during load decrease.
Next, adjustment in assembly of the spring 13 will be described with reference to
Accordingly, a shim 150 with a predetermined thickness is interposed in the spring 13 formed of a large number of disk springs to adjust the length of the spring 13. Thus, the stroke of the spring 13 is adjusted to be a set value X so that the output torque b and the axial force F2 between the second stage and the third stage become set values. The shim 150 enables to adjust the gap between the pressure receiving member 14 and the secondary cone 10 by the thickness or number thereof. This also adjusts the gap between the flange part 19 and the secondary cone 10, thereby adjusting the predetermined play amount l of the second torque cam 20. Note that, although the stroke of the spring 13 is adjusted by the shim 150, the present invention is not limited to this. The thickness of a part of the disk springs may be adjusted, or a length direction adjusting unit for the spring 13 such as a screw may be provided.
Note that, although the above-described embodiments are described with the pressing device 12, 112, 212 disposed in the secondary cone 10, 110, the present invention is not limited to this. The present invention may be applied even when the pressing device is disposed in the primary cone 2, or disposed in both the primary cone 2 and the secondary cone 10, 110. Further, the above description describes the friction type continuously variable transmission of cone ring type, but the present invention is not limited to this. The present invention may be applied to other friction type continuously variable transmissions such as a continuously variable transmission (ring cone type) in which a ring is disposed so as to surround both the two conical friction wheels, a continuously variable transmission in which a friction wheel contacting both friction wheels and moving in an axial direction is interposed between two cone-shaped friction wheels, a continuously variable transmission using a friction wheel having a spherical shape such as toroidal, and a continuously variable transmission in which friction disks of an input side and an output side are disposed to be sandwiched by pulley-like friction wheels formed of a pair of sheaves energized in a direction to come close to each other, and the pulley-like friction wheels are moved to change inter-axis distances to both the friction disks for shifting speed.
A friction type continuously variable transmission having a pressing device according to the present invention is preferable as a conical friction ring type continuously variable transmission, may be used as a power transmission in various fields such as industrial machines and transport machines, and may be used particularly as a transmission mounted on a vehicle.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-335125 | Dec 2008 | JP | national |
