Patent Application
20150018167
The present invention relates to an electric automobile drive apparatus that changes the speed (reduces the speed) of the output of an electric motor, and transmits that output to the driving wheels.
An electric motor that is the power source of an electric automobile generates maximum torque during start up, and in order for the torque and rotational speed characteristics of the output shaft to be favorable for an automobile, there is no need for there to be a transmission as in the case of a typical automobile having an internal combustion engine as the drive source. However, even in the case of an electric automobile, by providing a transmission, it is possible to improve the acceleration performance and high-speed performance. More specifically, by providing a transmission, it becomes possible to make the relationship between the traveling speed and acceleration of the vehicle smooth and approach that of an automobile in which a gasoline engine is installed and in which a transmission is provided in the power transmission system.
For example, when a power transmission apparatus having a large speed reducing ratio is provided between the output shaft of an electric motor that is the drive source of an electric automobile and the input shaft of a differential gear that is linked with the driving wheels, the relationship between the acceleration (G) and traveling speed (km/h) of the electric automobile is such that the left half of the solid line “a” and the chain line “b” in
In other words, one clutch mechanism 7a can be controlled by an actuator, and the other clutch mechanism 7b is constructed by an over-running clutch that becomes disengaged when the rotating speed becomes greater than a fixed value. When the one clutch mechanism 7a is engaged, the other clutch mechanism 7b becomes disengaged and idle, so the rotation torque of the driving-side rotating shaft 4 is transmitted to the driven-side rotating shaft 5 by way of the one gear transmission mechanism 6a having the small speed reducing ratio. When the one clutch mechanism 7a is in the disengaged state, the other clutch mechanism 7b is engaged, and the rotation torque of the driving-side rotating shaft 4 is transmitted to the driven-side rotating shaft 5 by way of the other gear transmission mechanism 6b having the large speed reducing ratio. The rotation transmission apparatus 3 transmits the rotation of the driven-side rotating shaft 5 to the input section of a differential gear 8, and rotates and drives the output shafts 9a, 9b that support the pair of left and right driving wheels.
Incidentally, by employing a continuously-variable transmission such as a toroidal continuously-variable transmission disclosed in JP 2007-315595 (A) and JP 2008-025821 (A) as a transmission that is assembled between a driving-side rotating shaft and a driven-side rotating shaft, the relationship between the traveling speed and the acceleration of a vehicle that is illustrated in
An electric automobile drive apparatus that comprises a mode that makes it possible to transmit the rotation of a driving-side rotating shaft to a driven-side rotating shaft while bypassing a continuously-variable transmission by providing a continuously-variable transmission and rotation transmission shaft between the driving-side rotating shaft (output shaft of an electric motor) and the driven-side rotating shaft (driving shaft) so as to be parallel to each other in the power transmission direction, and switching the clutch mechanism is disclosed in JP 2001-180312 (A). However, in this construction, there is room for further improvement in order to further improve the transmission efficiency of the electric automobile drive apparatus.
Taking into consideration the situation described above, it is the object of the present invention to provide an electric automobile drive apparatus that is capable of making the relationship between the traveling speed and acceleration of a vehicle smooth and closer to being ideal, and that is capable of maintaining the transmission efficiency.
By providing a continuously-variable transmission and a rotation-transmission shaft parallel to each other in the power transmission direction between a driving-side rotating shaft and a driven-side rotating shaft, and by switching clutch mechanisms, in construction that comprises only a mode in which the rotation of the driving-side rotating shaft bypasses the continuously-variable transmission and is transmitted to the driven-side rotating shaft, power is transmitted by way of the same power transmission path even when traveling in the low-speed high-torque range, or when traveling in the high-speed low-torque range. However, as can be seen in
The electric automobile drive apparatus of the present invention comprises a toroidal continuously-variable transmission and at least two clutch mechanisms that are provided between an input shaft that is rotated and driven by an electric motor and an output section that outputs power based on the rotation of the input shaft. The toroidal continuously-variable transmission comprises: an output disk, an input disk, plural support members, plural power rollers, and a mechanism that is able to regulate torque that is transmitted by the toroidal continuously-variable transmission. The output disk has an output-side curved surface that is a toroidal curved surface. The input disk is supported concentric with the output disk such that an input-side curved surface that is a toroidal curved surface faces the output-side curved surface, and so as to be able to rotate relative to the output disk. The support members are respectively arranged so as to be able to pivotally displace around pivot shafts that are located at positions that are skewed with respect to the center axis of the output disk and input disk. The power rollers are respectively supported by the support members so as to freely rotate, and are held between the output-side curved surface and the input-side curved surface.
Particularly, in the electric automobile drive apparatus of the present invention, it is possible to switch the transmission state between the input shaft and the output section among three modes: a bypass mode in which essentially all of the power from the electric motor is transmitted to the output section by bypassing the toroidal continuously-variable transmission; a low-speed mode in which all or part of the power from the electric motor undergoes a speed change by the toroidal continuously-variable transmission and is transmitted to the output section by way of the toroidal continuously-variable transmission, and a state having a speed reducing ratio that is larger than that in the bypass mode is achieved; and a high-speed mode in which all or part of the power from the electric motor undergoes a speed change by the toroidal continuously-variable transmission and is transmitted to the output section by way of the toroidal continuously-variable transmission, and a state having a speed reducing ratio that is smaller than that in the bypass mode (a state having a speed increasing ratio that is larger than that in the bypass mode) is achieved. In other words, the electric automobile drive apparatus of the present invention achieves a bypass mode by switching the engaged and disengaged states of the clutch mechanisms and controlling operation of the mechanism that is able to regulate torque that is transmitted by the toroidal continuously-variable transmission so as to keep the size of the torque that passes through the toroidal continuously-variable transmission to a minimum (ideally zero) regardless of the size of the output torque from the electric motor. Moreover, the electric automobile drive apparatus of the present invention switches between the low-speed mode and high-speed mode by switching the engaged and disengaged states of the clutch mechanisms and controlling operation of the mechanism that is able to regulate torque that is transmitted by the toroidal continuously-variable transmission according to the size of the output torque from the electric motor.
More specifically, the mechanism that is able to regulate the torque that is transmitted by the toroidal continuously-variable transmission is constructed by hydraulic actuators that comprise a pair of hydraulic chambers and that cause the support members to displace in the axial direction of the pivot shafts. By adjusting the supply of pressurized oil to the pair of hydraulic chambers, in the bypass mode, the hydraulic pressure of pressurized oil entering the pair of hydraulic chambers is the same regardless of the size of the output torque from the electric motor, and the hydraulic pressure difference (differential pressure) between the pair of hydraulic chambers is made to be zero. Moreover, in the low-speed mode and the high-speed mode, that differential pressure is a suitable size that corresponds to the size of the output torque from the electric motor.
Alternatively, the mechanism that is able to regulate the torque that is transmitted by the toroidal continuously-variable transmission is constructed by a hydraulic pressure apparatus that applies pressure in a direction that brings the input disk and output disk close together in order to maintain surface pressure in the traction sections, which are areas of rolling contact between the peripheral surfaces of the power rollers and the output-side curved surface and input-side curved surface. By adjusting the supply of pressurized oil to the pressure apparatus, in both the low-speed mode and the high-speed mode, the pressure that is generated by the pressure apparatus is a suitable size that corresponds to the size of the output torque from the electric motor. Moreover, in the bypass mode, the size of the pressure that is generated by the pressure apparatus is kept at a minimum (ideally zero) regardless of the size of the output torque from the electric motor.
Preferably, by adjusting the construction and assembly position of each of the elements of the electric automobile drive apparatus (gear mechanisms, clutch mechanisms and toroidal continuously-variable transmission), and the number of gears for making it possible to transmit power between these elements, the overall speed ratio of the electric automobile drive apparatus is made to match in the maximum speed increasing state in the low-speed mode, in the bypass mode, and in the maximum speed reducing state in the high-speed mode. More preferably, when traveling in the bypass mode, the support members are pivotally displaced around the pivot shafts, and the speed ratio of the toroidal continuously-variable transmission is adjusted.
Preferably, selectively or additionally, the toroidal continuously-variable transmission is a double-cavity toroidal continuously-variable transmission comprising a pair of input disks that are located at positions that are separated from each other in the axial direction, are concentric with each other, and are arranged such that the inside-side curved surfaces face each other, and an output-disk unit that is provided between the pair of input disks in a state such that the output-side curved surfaces face the input-side curved surfaces; with plural power rollers being held between each of the input-side curved surfaces of the pair of input disks and the output-side curved surfaces of the output-disk unit.
Preferably, at least one planetary-gear mechanism is provided between the input shaft and the output section.
In an embodiment in which this kind of planetary-gear mechanism is provided, the output section is constructed by a driven-side rotating shaft that is provided parallel to the input shaft, and that is rotated and driven by the input shaft by way of a gear power transmission mechanism. Moreover, a first planetary-gear mechanism and a second planetary-gear mechanism (two planetary-gear mechanisms) are provided around the driven-side rotating shaft.
The first planetary-gear mechanism comprises a first sun gear, a first ring gear, a first carrier and plural first planet gears. The first sun gear is supported around the driven-side rotating shaft so as to rotate freely with respect to the driven-side rotating shaft, and can be rotated and driven by the output disk. The first ring gear is arranged around the first sun gear, and is supported so as to freely rotate in synchronization with the driven-side rotating shaft. The first carrier is supported by a fixed part such as the casing so as not to be able to rotate. The first planet gears are supported by the first carrier so as to rotate freely, and transmit power between the first sun gear and the first ring gear.
The second planetary-gear mechanism comprises a second sun gear, a second ring gear, a second carrier and plural second planet gears. The second sun gear is supported around the driven-side rotating shaft so as to rotate freely with respect to the driven-side rotating shaft. The second ring gear is arranged around the second sun gear, and is supported so as to be able to be rotated and driven by the output disk. The second carrier is supported by a fixed part so as not to be able to rotate. The second planet gears are supported by the second carrier, and transmit power between the second ring gear and the second sun gear.
In this embodiment, three clutch mechanisms are provided. In other words, a first clutch mechanism is provided in the gear power transmission mechanism, and is engaged when achieving the bypass mode, and is disengaged when achieving the low-speed mode and high-speed mode; a second clutch mechanism is provided between the output disk and first sun gear, and is engaged when achieving the low-speed mode, and is disengaged when achieving the bypass mode and high-speed mode; and a third clutch mechanism is provided between the output disk and second ring gear, and is engaged when achieving the high-speed mode, and is disengaged when achieving the bypass mode and low-speed mode. More specifically, the gear power transmission mechanism is constructed by a bypass gear-transmission mechanism that has a driving-side gear that is provided so as to be concentric with the input shaft and so as to be able to rotate in synchronization with the input shaft, and a driven-side gear that is provided so as to be concentric with the driven-side rotating shaft, and so as to be able to rotate relative to the driven-side rotating shaft; and the first clutch mechanism is provided between the driven-side gear and the driven-side rotating shaft.
In another embodiment in which a planetary-gear mechanism is provided, the output section is constructed by a driven-side gear that is supported around the input shaft so as to rotate freely with respect to the input shaft, and so as to be able to transmit power from the output disk. Moreover, the planetary-gear mechanism is constructed by one planetary-gear mechanism having a sun gear, a ring gear, a carrier, and plural planet gears. The sun gear is supported around the input shaft so as to freely rotate relative to the input shaft. The ring gear is arranged around the sun gear and is connected to the input disk and the driven-side gear so as to be able to transmit the power separately. The carrier is supported between the sun gear and the ring gear so as to be concentric with the sun gear and the ring gear, and so as to be able to be rotated and driven by the input shaft. Moreover, the planet gears are supported by the carrier so as to rotate freely, and transmit power between the sun gear and the ring gear.
In this embodiment, two clutch mechanisms are provided. More specifically, a first clutch mechanism is provided between the ring gear and the driven-side gear, and is engaged when achieving the bypass mode and the low-speed mode, and is disengaged when achieving the high-speed mode; and a second clutch mechanism is provided between the output disk and the driven-side gear, and is engaged when achieving the bypass mode and the high-speed mode, and is disengaged when achieving the low-speed mode.
In yet another embodiment in which the planetary-gear mechanism is provided, the output section is constructed by a driven-side rotating shaft that is provided so as to be parallel to the input shaft and so as to be able to transmit power from the output disk. Moreover, the planetary-gear mechanism is constructed by one planetary-gear mechanism having a sun gear, a ring gear, a carrier and plural planet gears. The sun gear is supported around the driven-side rotating shaft so as to freely rotate in synchronization with the driven-side rotating shaft. The ring gear is arranged around the sun gear and is connected to the input shaft so as to be able to transmit power from the input shaft. The carrier is supported between the sun gear and the ring gear so as to be concentric with the sun gear and the ring gear, and so as to be able to be rotated and driven by the output disk. The planet gears are supported by the carrier so as to rotate freely, and transmit power between the sun gear and the ring gear.
In this embodiment, two clutch mechanisms are provided. More specifically, a first clutch mechanism is provided between the output disk and the driven-side rotating shaft, and is engaged when achieving the bypass mode and the low-speed mode, and is disengaged when achieving the high-speed mode; and a second clutch mechanism is provided between the input shaft and the ring gear, and is engaged when achieving the bypass mode and the high-speed mode, and is disengaged when achieving the low-speed mode.
With the present invention, construction of an electric automobile drive apparatus is achieved that is capable of making the relationship between the traveling speed and acceleration of a vehicle to be smooth and closer to the ideal, and that is capable of maintaining transmission efficiency. In other words, a toroidal continuously-variable transmission is used as a transmission mechanism that is provided between the output shaft of an electric motor and a rotation-transmission apparatus that is connected to the driving wheel. Therefore, it is possible to obtain acceleration performance and high-speed performance of a vehicle that is closer to or better than that of a gasoline-engine vehicle in which a typical transmission is installed. Moreover, in the present invention, it is possible to switch among modes (low-speed mode and high-speed mode) that transmit all or part of the output torque of the electric motor to the driving wheels by way of a toroidal continuously-variable transmission, and a mode (bypass mode) that transmits essentially all of the output torque from the electric motor by bypassing the toroidal continuously-variable transmission. Therefore, by operating in the bypass mode when traveling from the low-speed low-torque range to the intermediate-speed intermediate torque range, it is possible to maintain the overall transmission efficiency of the electric automobile drive apparatus. Furthermore, in the present invention, when transmitting the output torque from the electric motor, it is possible to switch between the low-speed mode having a large speed reducing ratio and the high-speed mode having a small speed reducing ratio. Therefore, the overall transmission efficiency of an electric automobile drive apparatus can be regulated within a better range for both the low-speed high-torque range and high-speed low-torque range.
The bypass gear-transmission mechanism 10 comprises a driving-side gear 14, a driven-side gear 15 and a first clutch mechanism 16. The driving-side gear 14 is provided in the middle section of the driving-side rotating shaft 4a, is concentric with the driving-side rotating shaft 4a and is able to rotate in synchronization with the driving-side rotating shaft 4a. The driving-side rotating shaft 4a is rotated and driven by the electric motor 1a, and as the driving-side gear 14 rotates, this rotation is transmitted to the driven-side gear 15 that engages with the driving-side gear 14. The driven-side gear 15 is provided around the driven-side rotating shaft 5a, is concentric with the driven-side rotating shaft 5a, and is able to rotate relative to the driven-side rotating shaft 5a. The first clutch mechanism 16 is controlled (caused to engage or disengage) by an actuator, and is provided between the driven-side gear 15 and the driven-side rotating shaft 5a.
The toroidal continuously-variable transmission 11 comprises a pair of input disks 17a, 17b, an integrated output disk 18, plural power rollers 19, plural trunnions 20 that corresponds to support members, the same number of actuators 21 as trunnions 20, and a pressure apparatus 22. The input disks 17a, 17b are supported around portions near both ends of an input rotating shaft 23 that is provided so as to be concentric with the driving-side rotating shaft 4a and so as to be able to rotate in synchronization with the input rotating shaft 23 with the inside surfaces (input-side curved surfaces), which are toroidal curved surfaces, facing each other. The output disk 18 is supported between the input disks 17a, 17b so as to be able to rotate relative to the input disks 17a, 17b with both side surfaces in the axial direction of the output disk 18 (output-side curved surfaces), which are toroidal curved surfaces, facing the inside surfaces of the input disks 17a, 17b.
The plural power rollers 19 are respectively held between the inside surfaces of the input disks 17a, 17b and both side surfaces of the output disk 18. As the power rollers 19 rotate with the input disks 17a, 17b, the power rollers 19 transmit power between the input disks 17a, 17b and the output disk 18. Each of the power rollers 19 is supported by the inside surface of a support beam 24 of a respective trunnion 20 by way of a support shaft 25, the base-end half and the tip-end half thereof being eccentric with each other, and plural rolling bearings, so as to be able to rotate around the tip-end half of the support shaft 25, and so as to be able to pivotally displace a little around the base-end section of the support shaft 25. A thrust ball bearing 26 and a thrust needle bearing 27, which are part of the plural rolling bearings, are provided in order from the power roller 19 side between the outside surface of the power roller 19 and the inside surface of the support beam 24 of the trunnion 20. The trunnions 20 are supported so as to be able to pivotally displace freely around pivot shafts 28a, 28b that are located in positions that are skewed with respect to the center axes of the input disks 17a, 17b and output disk 18. Moreover, the actuators 21 are hydraulic, and cause the trunnions 20 to displace in the axial direction of the pivot shafts 28a, 28b. In order for this, each actuators 21 is constructed so as to cause the outer peripheral edge of a seal ring 31 that is adhered around the outer-circumferential surface of a piston 30 to come into sliding contact with the inner-circumferential surface of a cylinder chamber 32, and this divides the inside of the cylinder chamber 29 into a pair of hydraulic chambers 32a, 32b that are separated so as to be oil tight from each other. A sleeve 34, which also functions as a lock nut, and a thrust rolling bearing 35b are provided in that order from the pivot shaft 28a side between a cylindrical section 33 that is provided in the center section of the piston 30 and the pivot shaft 28a that is provided on one end (bottom end in
The pressure apparatus 22 is constructed by a hydraulic pressure apparatus that, as pressurized oil enters in, generates a pressure force that is proportional to that pressurized oil, and presses the input disks 17a, 17b and the output disk 18 toward each other. As a result, surface pressure is maintained between the peripheral surfaces of the power rollers 19 and traction sections, which are rolling contact sections on the side surfaces of the input disks 17a, 17b and the output disk 18.
During operation of the toroidal continuously-variable transmission 11 (when power is transmitted), the driving-side rotating shaft 4a rotates and drives one input disk 17a by way of the pressure apparatus 22. As a result, the pair of input disks 17a, 17b that are supported by both end sections of the input rotating shaft 23 rotate in synchronization while being pressed toward each other. This rotation is transmitted to the output disk 18 by way of the plural power rollers 19, and obtained from an output gear 38 that is provided concentric with the output disk 18. The rotation of the output gear 38 is transmitted to a gear 39 that is supported around the driven-side rotating shaft 5a so as to be concentric with the driven-side rotating shaft 5a, and so as to be able to rotate freely with respect to the driven-side rotating shaft 5a. When changing the transmission gear ratio between the input rotating shaft 23 and the output gear 38, the trunnions 20 are caused to displace in the axial direction of the pivot shafts 28a, 28b according to the supply of pressurized oil to the actuators 21, which changes the directions of the tangential forces that act on the rolling contact sections (traction sections) between the peripheral surfaces of the power rollers 19 and the side surfaces of the input disks 17a, 17b and the output disk 18 (generates side slipping of the rolling contact sections). As the directions of the tangential forces change, the trunnions 20 pivot around the pivot shafts 28a, 28b, changing the positions of contact between the peripheral surfaces of the power rollers 19 and the side surfaces of the input disks 17a, 17b and output disk 18. By causing the peripheral surfaces of the power rollers 19 to come in contact with the portions near the outside in the radial direction of the inside surfaces of the input disks 17a, 17b and the portions near the inside in the radial direction of both side surfaces of the output disk 18, the transmission gear ratio between the input rotating shaft 23 and the output gear 38 is on the speed increasing side. On the other hand, by causing the peripheral surfaces of the power rollers 19 to come in contact with the portions near the inside in the radial direction of the inside surfaces of the input disks 17a, 17b and the portions near the outside in the radial direction of both side surfaces of the output disk 18, the transmission gear ratio between the input rotating shaft 23 and the output gear 38 is on the speed reducing side.
In this example, a half-toroidal continuously-variable transmission that is constructed as described above is used, however, in the present invention, it is also alternatively possible to use a full-toroidal continuously-variable transmission. Moreover, the construction of the portion in the half-toroidal continuously-variable transmission for supporting the power rollers by trunnions is not limited to the construction illustrated in
The first planetary-gear mechanism 12 for low speed comprises a first carrier 40, a first sun gear 41, plural first planet gears 42 and a first ring gear 43. The first planetary gear mechanism 12 is constructed by a single pinion planetary gear mechanism in which the first planet gears 42 are supported by the carrier 40 so as to rotate freely engage with both the first sun gear 41 and the first ring gear 43. The first carrier 40 is supported by and fastened to a stationary portion such as an installation section that is provided inside the casing so as not to rotate. The first ring gear 43 is supported by the driven-side rotating shaft 5a so as to be concentric with the driven-side rotating shaft 5a, and so as to be able to rotate in synchronization with the driven-side rotating shaft 5a. The first sun gear 41 is provided around the driven-side rotating shaft 5a so as to be concentric with the driven-side rotating shaft 5a, and so as to be able to rotate freely with respect to the driven-side rotating shaft 5a. A second clutch mechanism 44 that is capable of being controlled (engaged or disengaged) by an actuator is provided between the gear 39 and first sun gear 41.
The second planetary-gear mechanism 13 for high speed comprises a second carrier 45, a second sun gear 46, plural second planet gears 47 and a second ring gear 48. The second planetary gear mechanism 13, as in the case of the first planetary gear mechanism 12, is constructed by a single pinion planetary gear mechanism in which the second planet gears 47 that are supported by the second carrier 45 so as to rotate freely engage with both the second sun gear 46 and second ring gear 48. The second carrier 45 is supported by and fastened to a stationary portion such as an installation section that is provided inside the casing so as not to rotate. The second sun gear 46 is supported around the driven-side rotating shaft 5a so as to be concentric with the driven-side rotating shaft 5a, and so as to rotate in synchronization with the driven-side rotating shaft 5a. The second ring gear 48 is supported so as to be able to rotate freely with respect to the driven-side rotating shaft 5a, and a third clutch mechanism 49 that is capable of being controlled (engaged or disengaged) by an actuator is provided between the gear 39 and second ring gear 48. In this example, the ratio between the number of teeth m48 of the second ring gear 48 and the number of teeth m46 of the second sun gear 46 (m48/m46) is equal to the ratio between the number of teeth m43 of the first ring gear 43 and the number of teeth m41 of the first sun gear (m43/m41) (m48/m46=m43/m41), and the speed reducing ratio of the second planetary-gear mechanism 13 (m48/m46) equals the speed reducing ratio of the first planetary-gear mechanism 12 (m43/m41). However, it is also possible for the speed reducing ratios of the first planetary-gear mechanism 12 and the second planetary-gear mechanism 13 to be different from each other.
The electric automobile drive apparatus of this example switches between a transmitting state or non-transmitting state for transmitting power between the input disks 17a, 17b and output disk 18, by switching between the engaged state and disengaged state of each of the three clutch mechanisms 16, 44, 49 according to the rotational speed and rotational torque of the output shaft of the electric motor 1a, and by controlling the operation of a mechanism (at least one member of the pressure apparatus 22 and actuators 22) that is a member of the toroidal continuously-variable transmission 11 and that regulates the torque that is transmitted by the toroidal continuously-variable transmission 11. As a result, it is possible to switch the transmission state among three modes: a bypass mode in which the rotation of the driving-side rotating shaft 4a bypasses the toroidal continuously-variable transmission 11 and is transmitted to the driven-side rotating shaft 5a; a low-speed mode in which the rotation of the driving-side rotating shaft 4a undergoes a change in speed (reduction in speed) by the toroidal continuously-variable transmission 11 and first planetary-gear mechanism 12, and is then transmitted to the driven-side rotating shaft 5a, achieving a state having a larger speed reducing ratio than that in the bypass mode; and a high-speed mode in which the rotation of the driving-side rotating shaft 4a undergoes a change in speed (reduction in speed) by the toroidal continuously-variable transmission 11 and second planetary-gear mechanism 13, and is then transmitted to the driven-side rotating shaft 5a, achieving a state having a smaller speed reducing ratio than that in the bypass mode.
In the bypass mode, a state is set in which the first clutch mechanism 16 is engaged, and the second clutch mechanism 44 and third clutch mechanism 49 are disengaged, operation of the mechanism (pressure apparatus 22 and/or hydraulic actuators 21) that regulate the torque that is transmitted by the toroidal continuously-variable transmission 11 is controlled, and power is not transmitted between the input disks 17a, 17b and the output disk 18. In order for this, the pressure that is generated by the pressure apparatus 22 is set to a minimum value, ideally zero, by adjusting the supply of pressurized oil to the pressure apparatus 22 regardless of the size of the rotation torque of the driving-side rotating shaft 4a. As a result, the surface pressure in the traction sections that are rolling contact sections between the peripheral surfaces of the power rollers 19 and the side surfaces of the input disks 17a, 17b and output disk 18 becomes close to zero. In other words, essentially all of the power from the electric motor 1a bypasses the toroidal continuously-variable transmission 11 and is transmitted to the driven-side rotating shaft 5a, which is the output section.
It is also possible to achieve a state in which power is not transmitted between the input disks 17a, 17b and the output disk 18 by adjusting the supply of pressurized oil to the actuators 21 having a pair of hydraulic chambers 28a, 28b in addition to or alternative to controlling the pressure force generated by the pressure apparatus 22. In other words, the difference in the pressurized oil (differential pressure) existing between the pair of hydraulic chambers 28a, 28b of the actuators 21 is set to zero regardless of the size of the rotation torque of the driving-side rotating shaft 4a (the pressure of the pressurized oil entering inside the hydraulic chambers 28a, 28b is the same as each other). More specifically, during execution of the bypass mode, the pressurized oil entering into the hydraulic chambers 28a, 28b is controlled so that the hydraulic pressure inside the hydraulic chambers 28a, 28b is the same. Alternatively, it is possible to connect (forcibly) the hydraulic chambers 28a, 28b together, or it is also possible to connect both of the hydraulic chambers 28a, 28b to a drain (hydraulic power source having a hydraulic pressure of zero). In either case, by making the differential pressure that exists between the hydraulic chambers 28a, 28b zero, the force that is applied to the trunnions during operation of (during transmission of power by) a toroidal continuously-variable transmission 10b (known traction force that is called 2Ft in the field of toroidal continuously-variable transmission technology) is not supported, and torque is not transmitted by the toroidal continuously-variable transmission 10b.
In construction in which in the bypass mode in which essentially all of the output torque of the electric motor 1a bypasses the toroidal continuously-variable transmission and is transmitted to the driven-side rotating shaft 5a, which is the output section, only control is performed so that the hydraulic pressure of the pressurized oil entering in the pair of hydraulic chambers of the actuators 21 is the same, it is possible to provide a mechanical device such as a loading cam as the pressure apparatus 22 that presses the input disks 17a, 17b and output disk 18 in a direction toward each other.
As described above, by performing at least one of control to make the pressure force that is generated by the pressure apparatus 22 a minimum, and control to make the hydraulic pressure of the hydraulic chambers 28a, 28b of the actuators 21 the same, power is not transmitted between the input disks 17a, 17b and the output disk 18 or the transmission of power is kept very small. As a result, rotation of the driving-side rotating shaft 4a bypasses the toroidal continuously-variable transmission 11 as illustrated by the bold lines in
In the low-speed mode, together with engaging the second clutch mechanism 44 and disengaging the first clutch mechanism 16 and the third clutch mechanism 49, the operation of a mechanism (pressure apparatus 22 and/or hydraulic actuators 21) that regulates torque that is transmitted by the toroidal continuously-variable transmission 11 is controlled, and a state is set in which power is transmitted between the input disks 17a, 17b and the output disk 18. In other words, the pressure force that is generated by the pressure apparatus 22 and the differential pressure between the pair of hydraulic chambers 28a, 28b of the actuators 21 are each set to appropriate sizes according to the size of the rotation torque of the driving-side rotating shaft 4a. As a result, as illustrated by the bold lines in
In the high-speed mode, the third clutch mechanism 49 is engaged, and the first clutch mechanism 16 and second clutch mechanism 44 are disengaged, and as in the case of the low-speed mode, the operation of a mechanism (pressure mechanism 22 and/or hydraulic actuators 21) that regulates the torque that is transmitted by the toroidal continuously-variable transmission 11 is controlled, and a state is set to transmit power between the input disks 17a, 17b and the output disk 18. As a result, as illustrated by the bold lines in
The electric automobile drive apparatus of this example, by switching the three clutch mechanisms 16, 44, 49 according to the output of the electric motor 1a (rotational speed and rotational torque of the output shaft of the electric motor 1a), and controlling the operation of the mechanism (pressure apparatus 22 and/or hydraulic actuators 21) that regulate the torque transmitted by the toroidal continuously-variable transmission 11, is able to switch between three modes: a bypass mode, low-speed mode and high-speed mode. More specifically, the low-speed mode is when the output from the electric motor 1a is in the low-speed high-torque range, the bypass mode is when the output from the electric motor 1a is from the low-speed low-torque range to the intermediate-speed intermediate-torque range, and the high-speed mode is when the output from the electric motor 1a is in the high-speed and low-torque range. Particularly, in the case of the electric automobile drive apparatus of this example, in a state in which the speed ratio of the toroidal continuously-variable transmission 11 is 1 or near 1 (for example, in a range of 0.5 or more to 1.5 or less), the mode is switched to the bypass mode. In this way, by operating the vehicle in the bypass mode when traveling from the low-speed high-torque range to the intermediate speed and intermediate torque range where the torque loss of the toroidal continuously-variable transmission 11 becomes relatively large, the overall transmission efficiency of the electric automobile drive apparatus is maintained. On the other hand, during operation in the low-speed mode or high-speed mode, by adjusting the speed ratio of the toroidal continuously-variable transmission 11, the overall transmission efficiency of the toroidal continuously-variable transmission 11 is in a suitable range found from
Moreover, in this example, by adjusting the construction and assembly locations of each of the components (bypass gear-transmission mechanism, two planetary-gear mechanisms 12, 19, three clutch mechanisms 16, 44, 49 and toroidal continuously-variable transmission 11) of the electric automobile drive apparatus, and the number of gears for making it possible to transmit power between these elements, the overall speed ratios of the electric automobile drive apparatus (1/speed reducing ratio, speed increasing ratio) are made to match in the maximum speed increasing state in the low-speed mode, in the bypass mode and in the maximum deceleration state in the high-speed mode. When traveling in the bypass mode, construction is such that the trunnions 20 of the toroidal continuously-variable transmission 11 are caused to pivotally displace around the pivot shafts 28a, 28b, and the speed ratio of the toroidal continuously-variable transmission 11 (speed ratio between the input disks 17a, 17b and the output disk 18) is caused to change. The reason for this is to prevent or reduce the overall speed ratio of the electric automobile drive apparatus from becoming non continuous when switching between the low-speed mode and the bypass mode, and when switching between the bypass mode and high-speed mode. In other words, when switching from the low-speed mode to the high-speed mode by way of the bypass mode, during the vehicle travelling in the bypass mode, the speed ratio of the toroidal continuously-variable transmission 11 is caused to change from a value that achieves the overall maximum speed increasing state of the electric automobile drive apparatus in the low-speed mode to a value that achieves the overall maximum speed reducing state of the electric automobile drive apparatus in the high-speed mode. On the other hand, when switching from the high-speed mode to the low-speed mode by way of the bypass mode, during the vehicle travelling in the bypass mode, the speed ratio of the toroidal continuously-variable transmission 11 is caused to change in the opposite direction from in the case when switching from the low-speed mode to the high-speed mode.
With the electric automobile drive apparatus of this example, it is possible to make the relationship between the traveling speed and acceleration of a vehicle smooth and closer to the ideal, and it is possible to improve the transmission efficiency. In other words, the output torque of the electric motor 1a undergoes a change in speed by the toroidal continuously-variable transmission 11, and is transmitted to the rotation-transmission apparatus 3a. Therefore, the acceleration performance and high-speed performance of a vehicle, when compared with the conventional construction illustrated in
In this example, as long as it is possible to achieve three modes: bypass mode, low-speed mode and high-speed mode, the construction and assembly location of each of the elements (planetary gear mechanisms 12, 13, clutch mechanisms 16, 44, 49 and toroidal continuously-variable transmission 11) of the electric automobile drive apparatus, and the number of gears for making it possible to transmit power between these elements can be suitably changed.
The first gear 57 is able to rotate and drive an intermediate shaft 60 that is provided so as to be concentric with the toroidal continuously-variable transmission 11 and an input rotating shaft 23 by engaging with an intermediate gear 61 that is provided around the intermediate shaft 60 so as to be able rotate in synchronization with the intermediate shaft 60. When the toroidal continuously-variable transmission 11 is operating (when power is being transmitted), the rotation of the intermediate shaft 60 is transmitted to the input disks 17a, 17b by way of the pressure apparatus 22, the speed is changed between the input disks 17a, 17b and the output disk 18, and that rotation is then obtained from an output gear 38 that is provided so as to be concentric with the output disk 18. Then, the rotation of the output gear 38 is transmitted by way of an intermediate gear 62 to a second gear 63 that is supported by the other end section in the axial direction (right end section in
In this example, by adjusting the engaged and disengaged (engagement) state of the two clutch mechanisms 58, 59, and the operation of the mechanism (pressure apparatus 22 and/or hydraulic actuators 21) that regulate the torque that is transmitted by the toroidal continuously-variable transmission 11, it is possible to switch among three modes. In other words, in the bypass mode, both of the clutch mechanisms 58, 59 are engaged, and operation of at least one of the pressure mechanism 22 and the hydraulic actuators 21 that cause the trunnions 20 (see
In this example, in the low-speed mode, the more the speed ratio of the toroidal continuously-variable transmission 11 is changed to the speed increasing side, the overall speed ratio of the electric automobile drive apparatus also changes to the speed increasing side. On the other hand, in the high-speed mode, the more the speed ratio of the toroidal continuously-variable transmission 11 is changed to the speed reducing side, the overall speed ratio of the toroidal continuously-variable transmission 11 changes to the speed increasing side. Moreover, the overall speed ratio of the toroidal continuously-variable transmission 11 is made to match on the maximum speed increasing side in the low-speed mode, in the bypass mode, and on the maximum speed reducing side in the high-speed mode. In this example, switching between the low-speed mode and the bypass mode, and switching between the bypass mode and the high-speed mode is performed at or near the maximum speed increasing ratio of the toroidal continuously-variable transmission 11. As a result, when switching modes, it is possible to prevent or reduce the extent of which the overall speed ratio of the electric automobile drive apparatus becomes non continuous, and it becomes possible to perform detailed adjustment of the overall speed ratio of the electric automobile drive apparatus.
With the electric automobile drive apparatus of this example, in both the low-speed mode and high-speed mode, it is possible to achieve a so-called power-split state in which part of the power of the driving-side rotating shaft 4a bypasses the toroidal continuously-variable transmission 11 and is transmitted. As a result, it is possible to keep the power that is inputted to the toroidal continuously-variable transmission 11 small, and to improve the durability of the toroidal continuously-variable transmission 11. Moreover, in this example, in the bypass mode, the overall planetary-gear mechanism 51 rotates as one, so a state is set in which power is not transmitted between the sun gear 54 and the ring gear 55 by way of the planet gears 53. As a result, it is possible to eliminate energy loss due to engagement of gears inside the planetary-gear mechanism 51, and it is possible to achieve a highly efficient electric automobile drive apparatus. The construction and functions of other parts are the same as in the first example of an embodiment.
In this example, the bypass clutch mechanism 68 is engaged, and the low-speed clutch mechanism 69 and high-speed clutch mechanism 70 are disengaged, and the operation of a mechanism that is able to regulate the torque that is transmitted by the toroidal continuously-variable transmission 11, or more specifically, the operation of at least one of a pressure apparatus 22 and hydraulic actuators 21 (see
In regards to the construction of the first example of an embodiment of the electric automobile drive apparatus of the present invention illustrated in
In Example 1, the gear ratio of the first planetary-gear mechanism 12 (number of teeth of the ring gear 43/number of teeth of the sun gear 41) and the gear ratio of the second planetary-gear mechanism 13 (number of teeth of the ring gear 48/number of teeth of the sun gear 46) were both set to 1.5, the gear ratio of the rotation transmission apparatus 3a (number of teeth of the output-side gear/number of teeth of the input-side gear) was set to 4, and the gear ratio of the bypass gear-transmission mechanism 10 (number of teeth of the driven-side gear 15/number of teeth of the driving-side gear 14) was set to 1. In this way, the overall speed ratio of the electric automobile drive apparatus was made to match in the case in which the speed ratio of the toroidal continuously-variable transmission 11 in the low-speed mode is approximately 1.5, in the case of the bypass mode, and in the case in which the speed ratio of the toroidal continuously-variable transmission 11 in the high-speed mode is approximately 0.6.
When the electric automobile drive apparatus was caused to operate under such conditions, the relationship between the overall speed ratio of the electric automobile drive apparatus and the speed ratio of the toroidal continuously-variable transmission 11 was as illustrated in
In regards to the construction of the second example of an embodiment of the electric automobile drive apparatus of the present invention illustrated in
In Example 2, the gear ratio of the planetary-gear mechanism 51 (number of teeth of the ring gear 55/number of teeth of the sun gear 54) was set to 2, the gear ratio of the rotation transmission apparatus 3a (number of teeth of the output-side gear/number of teeth of the input-side gear) was set to 4, the gear ratio between the first gear 57 and the intermediate gear 61 (number of teeth of the intermediate gear 61/number of teeth of the first gear 57) was set to 2, and the gear ratio between the second gear 63 and the output gear 38 (number of teeth of the output gear 38/number of teeth of the second gear 63) was set to 0.784. With this kind of construction, the overall speed ratio of the electric automobile drive apparatus was made to match each other on the maximum speed increasing side in the low-speed mode, in the bypass mode, and on the maximum speed reducing side in the high-speed mode. At the same time, in a state in which the speed ratio of the toroidal continuously-variable transmission 11 was on the maximum speed increasing side (approximately 2.5), the overall speed ratio of the electric automobile drive apparatus was controlled so as to be on the maximum speed increasing side in the low-speed mode and on the maximum speed reducing side in the high-speed mode.
When the electric automobile drive apparatus was operated under such conditions, the relationship between the overall speed ratio of the electric automobile drive apparatus and the speed ratio of the toroidal continuously-variable transmission 11 was as illustrated in
In regards to the construction of the third example of an embodiment of the electric automobile drive apparatus of the present invention illustrated in
In Example 3, the gear ratio of the planetary-gear mechanism (number of teeth of the ring gear 55a/number of teeth of the sun gear 54a) was set to 2, the gear ratio of the rotation-transmission apparatus 3a (number of teeth of the output-side gear/number of teeth of the input-side gear) was set to 4, the gear ratio between the driving-side gear 14 and the first driven-side gear 64 (number of teeth of the first driven-side gear 64/number of teeth of the driving-side gear 14) was set to 1, and the gear ratio between the second driven-side gear 65 and the output gear 38 (number of teeth of the output gear 38/number of teeth of the second driven-side gear 65) was set to 0.3922. With this kind of construction, the overall speed ratio of the electric automobile drive apparatus was made to match on the maximum speed increasing side in the low-speed mode, in the bypass mode and on the maximum speed reducing side in the high-speed mode. Moreover, in this example, the speed ratio of the toroidal continuously-variable transmission 11 could be adjusted in the range 0.3922 to 2.550, and in a state in which the speed ratio of the toroidal continuously-variable transmission 11 was on the maximum speed increasing side, the overall speed ratio of the electric automobile drive apparatus was on the maximum speed increasing side in the low-speed mode, and on the maximum speed reducing side in the high-speed mode.
When the electric automobile drive apparatus is operated under these conditions, the relationship between the overall speed ratio of the electric automobile drive apparatus and the speed ratio of the toroidal continuously-variable transmission 11 was as illustrated in
The present invention makes it possible in an electric automobile drive apparatus in which a toroidal continuously-variable transmission is assembled in the power transmission path to maintain the overall transmission efficiency of the electric automobile drive apparatus. Therefore, with the present invention, in an electric automobile drive apparatus, it is possible to actively use a toroidal continuously-variable transmission as the transmission mechanism, and it is possible to make the acceleration performance and high-speed performance of an electric automobile in which the present invention is applied close to or better than that of a gasoline engine automobile in which a typical transmission is installed. In this way, the present invention greatly contributes to electric automobile drive apparatuses and the field of electric automobiles.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-145193 | Jul 2013 | JP | national |
