Vehicle drive system

Abstract

To increase vehicle driving force without increasing the size of a vehicle drive device.SOLUTION: A vehicle drive device 100 includes: motors 11, 12 as travel drive sources; a transmission 2 that has an input shaft to which torque is input, a transmission mechanism that changes the speed of the rotation of the input shaft, and a transmission case that stores the input shaft and the transmission mechanism; a rotary shaft 15 that extends coaxially with the input shaft on the outside of the transmission case, and is connected to the input shaft; and a power transmission unit that transmits torque from the motors 11, 12 to the rotary shaft 15. The motors 11, 12 are arranged at substantially-symmetrical positions with the rotary shaft 15 as the symmetrical axis.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive device having a plurality of electric motors as a drive source for traveling. [Background technology]

[0002] Vehicles equipped with multiple motors for driving the vehicle have been known (see, for example, Patent Document 1). In Patent Document 1, a motor (in-wheel motor) is built into each wheel of the vehicle, and each wheel is driven to rotate by the driving of each motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6355927 Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Document 1, when multiple motors for driving the vehicle are configured as in-wheel motors, the driving force of each motor drives each wheel, which requires a large motor to increase the driving force of the wheels, resulting in an increase in the size of the device. [Means for solving the problem]

[0005] A vehicle drive device according to one aspect of the present invention includes a transmission having a first electric motor and a second electric motor that are drive sources for driving the vehicle, an input shaft to which torque is input, a speed change mechanism that changes the rotation of the input shaft, and a transmission case that houses the input shaft and the speed change mechanism, a rotating shaft that extends coaxially with the input shaft outside the transmission case and is connected to the input shaft, a first power transmission unit that transmits torque from the first electric motor to the rotating shaft, and a second power transmission unit that transmits torque from the second electric motor to the rotating shaft. the first power transmission unit has an endless first belt-shaped member that is looped between a first output unit, from which torque of the first electric motor is output, and a first portion of the rotating shaft; the second power transmission unit has an endless second belt-shaped member that is looped between a second output unit, from which torque of the second electric motor is output, and a second portion of the rotating shaft; The first electric motor and the second electric motor are disposed at positions approximately symmetrical with respect to the rotation axis. [Effects of the Invention]

[0006] According to the present invention, the driving force of the wheels can be increased without using a large motor, and the device can be made smaller. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a side view of a vehicle to which a vehicle drive device according to an embodiment of the present invention is applied; [Figure 2] Arrow II view of Figure 1. [Figure 3] 1 is a perspective view showing the overall configuration of a vehicle drive device according to an embodiment of the present invention; [Figure 4] 1 is a side view showing the overall configuration of a vehicle drive device according to an embodiment of the present invention; [Figure 5] 1 is an exploded perspective view of a drive unit that is a part of a vehicle drive device according to an embodiment of the present invention; [Figure 6] FIG. 6 is a cross-sectional view of a main part of the drive unit of FIG. 5. [Figure 7A] FIG. 6 is a perspective view of a case that constitutes the drive unit of FIG. 5. [Figure 7B] FIG. 7B is a perspective view of the case as seen from a different direction from FIG. 7A. [Figure 8] FIG. 6 is a perspective view of a holder that constitutes the drive unit of FIG. 5. [Figure 9] FIG. 6 is a perspective view of a bracket that constitutes the drive unit of FIG. 5. [Figure 10] 6 is a cross-sectional view showing the configuration of a connection portion between a rotary shaft of the drive unit and an input shaft of a transmission in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 10. A vehicle drive device according to an embodiment of the present invention is a device for driving a vehicle, and can be applied to various vehicles such as passenger cars, trucks, and work vehicles. Below, an example in which the vehicle drive device is applied to a four-wheel truck will be described as an example.

[0009] Fig. 1 is a side view of a vehicle (truck) 200 equipped with a vehicle drive device 100 according to an embodiment of the present invention, and Fig. 2 is a bottom view (view along arrow II in Fig. 1) of the vehicle 200 showing a schematic configuration of the vehicle drive device 100. Note that in Figs. 1 and 2, the front-rear direction (length direction), left-right direction (width direction), and up-down direction (height direction) of the vehicle 200 are indicated by arrows.

[0010] 1, vehicle 200 has a pair of left and right front wheels 201, a pair of left and right rear wheels 202, a cabin 203 arranged above the front wheels 201, a chassis (body frame) 204 forming the skeleton of vehicle 200, and a cargo bed 205 arranged above chassis 204. Vehicle 200 is a rear-wheel drive vehicle configured with front wheels 201 as driven wheels and rear wheels 202 as drive wheels, and rear wheels 202 are driven by vehicle drive device 100. Vehicle drive device 100 is arranged below chassis 204 and in the vicinity of rear wheels 202.

[0011] For convenience, in FIG. 2, the rear wheels 202 and the left and right drive shafts 206 connected to the rear wheels 202 are each shown by a two-dot chain line. Only the outermost contour of the chassis 204 is shown by a solid line. As shown in FIG. 2, the vehicle driving device 100 is disposed between the left and right rear wheels 202. The front end of the vehicle driving device 100 is located forward of the front ends of the rear wheels 202, and the rear end is located rearward of the drive shafts 206 and forward of the rear ends of the rear wheels 202.

[0012] The vehicle drive system 100 has a drive unit 1, a transmission 2, and a differential mechanism 3. The drive unit 1 is attached to the left end of the transmission 2, and torque output from the drive unit 1 is input to the input shaft of the transmission 2. The transmission 2 changes the rotation of the input shaft at a predetermined gear ratio. The differential mechanism 3 is provided at the rear of the transmission 2, and distributes the torque output from the transmission 2 to the left and right, transmitting it to left and right drive shafts 206. This rotates the drive shafts 206, driving the left and right rear wheels 202.

[0013] The vehicle drive device 100 is supported by a plurality of support parts 211 to 213 provided on the bottom of the chassis 204. Specifically, left a support portion 211 provided at the front; right The device is supported by a support portion 212 provided at the front and a support portion 213 provided at the rear and in the center in the left-right direction via a well-known mounting mechanism.

[0014] Assuming that an engine is originally connected to transmission 2 and drive unit 1 is connected in place of the engine, drive unit 1 is configured to be approximately the same size as the engine overall. This allows drive unit 1 to be placed directly in the engine installation space, and the engine mount can be reused as a support for vehicle drive device 100. This makes it possible to easily and inexpensively convert an engine vehicle that has an engine as a driving source into an electric vehicle that has drive unit 1.

[0015] 3 is a perspective view (viewed from diagonally forward left and above) showing the overall configuration of the vehicle drive device 100. As shown in FIGS. 2 and 3, the transmission 2 has a transmission case 20 and a transmission mechanism 21 housed in the transmission case 20. Although not shown, the transmission mechanism 21 has an input shaft and an output shaft rotatably supported by the transmission case 20 and extending parallel to each other in the left-right direction, and multiple gear stages that transmit rotation of the input shaft to the output shaft. The transmission case 20 is configured in a substantially cylindrical shape centered on an axis CL1 (see FIG. 4) that extends in the left-right direction so as to house the input shaft, output shaft, and multiple gear stages.

[0016] 4 is a side view (enlarged view of the main part of FIG. 1) of the vehicle drive device 100 as viewed from the left. As shown in FIG. 4, the differential mechanism 3 is provided so as to bulge rearward from the transmission 2. The bottom surfaces of the differential mechanism 3 and the transmission 2 are located on the same or nearly the same horizontal plane. Behind the transmission 2, a drive shaft 206 protrudes in the left-right direction from both left and right end surfaces of the differential mechanism 3.

[0017] The vehicle drive device 100 of this embodiment is characterized by the configuration of the drive unit 1. Fig. 5 is an exploded perspective view of the drive unit 1. As shown in Figs. 3 to 5, the drive unit 1 has a pair of front and rear motors 11, 12, a holder 13 that supports the motors 11, 12, a case 14 that supports the holder 13, a rotating shaft 15 that is rotatably supported inside the case 14, a pair of power transmission units 16, 17 that transmit the torque of the motors 11, 12 to the rotating shaft 15, and a bracket 18 for attaching the drive unit 1 to the chassis 204.

[0018] The rotating shaft 15 extends in the left-right direction along an axis line CL1 that passes through the center of the rotating shaft 15. In the following, a direction parallel to the axis line CL1 may be referred to as an axial direction, a direction extending radially from the axis line CL1 (a direction perpendicular to the axis line CL1) as a radial direction, and a direction along which a circle centered on the axis line CL1 extends as a circumferential direction.

[0019] The motors 11 and 12 are electric motors of the same configuration, and are formed, for example, by three-phase AC synchronous motors. As shown in FIG. 1, a battery 250 is mounted in front of the vehicle drive device 100 and below the chassis 204. DC power from the battery 250 is converted into three-phase AC power by a power conversion circuit (not shown) and supplied to the motors 11 and 12. This drives the pair of motors 11 and 12 simultaneously. Note that the torques output from the motors 11 and 12 when the vehicle is traveling are the same. Using the two motors 11 and 12 as a traveling drive source makes it possible to generate a large traveling drive torque without using a large motor.

[0020] As shown in FIG. 4, one motor 11 is disposed in front of and below the rotating shaft 15. The bottom surface of the motor 11 is located on the same horizontal plane as the bottom surface of the transmission 2. The other motor 12 is disposed behind the rotating shaft 15 and between the drive shaft 206 and the chassis 204. As described above, in this embodiment, the pair of motors 11 and 12 are disposed substantially symmetrically with respect to the rotating shaft 15, with the rotating shaft 15 serving as the axis of symmetry. As a result, as shown in FIG. 1, the angle θ formed by a pair of line segments extending from the center of the rotating shaft 15 (axis line CL1) to the centers of the motors 11 and 12, respectively (referred to as the crossing angle), becomes large. Here, "substantially symmetrical" refers to a case where the crossing angle θ is equal to or greater than a predetermined angle θ1 (e.g., 135°), and also includes a case where the crossing angle θ is 180° in the strict sense.

[0021] If the front motor 11 were positioned so that the crossing angle θ was 180° while the rear motor 12 was positioned above the drive shaft 206, the bottom surface of the motor 11 would be located lower than the bottom surface of the transmission 2, and the distance from the road surface to the motor 11 (minimum ground clearance) would be shorter. On the other hand, if the front motor 11 were positioned in the position shown in FIG. 4 and the motor 12 were positioned so that the crossing angle θ was 180°, there is a risk of interference between the motor 12 and the drive shaft 206. Therefore, the crossing angle θ is set to a value equal to or greater than a predetermined angle θ1 so that the rear motor 12 is positioned without interfering with the drive shaft 206 while ensuring sufficient ground clearance for the front motor 11. Preferably, the crossing angle θ is set to a value as close to 180° as possible (180° if possible).

[0022] 5, the output shafts of the motors 11 and 12 extend in the left-right direction parallel to the axis CL1, and are provided at their distal ends (right ends) with drive pulleys 111 and 121 of identical configuration. The rear motor 12 is disposed a predetermined length to the right of the front motor 11, and the drive pulley 121 is located a predetermined length to the right of the drive pulley 111. The distances from the axis CL1 to the output shafts of the motors 11 and 12 are equal to each other.

[0023] The power transmission units 16, 17 are positioned with a lateral offset from each other. The left-side power transmission unit 16 has a driven pulley 161 with a larger diameter than the drive pulley 111 and an endless belt 162. The belt 162 is looped between the driven pulley 161 and the drive pulley 111 in front of it, and the rotation of the drive pulley 111 is reduced in speed via the belt 162 and transmitted to the driven pulley 161. The right-side power transmission unit 17 has a driven pulley 171 with a larger diameter than the drive pulley 121 and an endless belt 172. The belt 172 is looped between the driven pulley 171 and the drive pulley 121 behind it, and the rotation of the drive pulley 121 is reduced in speed via the belt 172 and transmitted to the driven pulley 171. The driven pulleys 161 and 171 have the same configuration (diameter and width), and the belts 162 and 172 also have the same configuration (length and width).

[0024] The driven pulleys 161 and 171 are attached to the rotary shaft 15 so as to rotate integrally with the rotary shaft 15. FIG. 6 is a cross-sectional view of the main part of the drive unit 1 taken along the axis CL1. As shown in FIGS. 5 and 6, the rotary shaft 15 has a stepped outer circumferential surface, and has a large diameter portion 151 and a stepped portion 152 extending from the large diameter portion 151. left The small diameter portion 152 extends toward the large diameter portion 151. right 6, the large diameter portion 151 has an inner ring of a ball bearing 41 attached to the outer peripheral surface of the large diameter portion 151. The outer ring of the ball bearing 41 is attached to the inner peripheral surface of a substantially ring-shaped bearing support portion 141 centered on the axis CL1 provided on the case 14. In this way, the rotating shaft 15 is rotatably supported by the case 14 via the ball bearing 41.

[0025] A washer 42, a driven pulley 171, a collar 43, and a driven pulley 161 are fitted onto the outer peripheral surface of the small diameter portion 152, in that order from the right. A threaded hole 154 is provided at the left end of the rotating shaft 15, and a bolt 44 is threaded into the threaded hole 154. The washer 42, the driven pulley 171, the collar 43, and the driven pulley 161 are sandwiched and fixed between the seating surface of the bolt 44 and the left end face of the large diameter portion 151. The inner ring of the bearing 41 is sandwiched and fixed between the end face of a step portion 151a provided on the outer peripheral surface of the large diameter portion 151 and the washer 42. The outer ring of the bearing 41 is sandwiched and fixed between a side wall portion 142 extending radially inward from the left end of the bearing support portion 141 and a circlip (snap ring) 45 fitted into a groove on the inner peripheral surface of the bearing support portion 141.

[0026] Case 14 is generally cylindrical in shape and covers the periphery of rotary shaft 15 and driven pulleys 161, 171. As shown in Fig. 5, case 14 has a base 143 provided at the right end, a flange 144 provided at the left end, and a sidewall 145 extending in the left-right direction and connecting base 143 and flange 144.

[0027] The side wall portion 145 is inclined so as to approach the axis CL1 as it goes leftward, and the size of the flange portion 144 centered on the axis CL1, that is, the overall size of the flange portion 144 on a plane perpendicular to the axis CL1, is smaller than the overall size of the base portion 143 centered on the axis CL1. As shown in Fig. 3, the base portion 143 is formed with a generally L-shaped cross section so as to cover the periphery of the left end portion of the transmission case 20, which allows the case 14 to be positioned with respect to the transmission case 20 with high precision.

[0028] 7A is a perspective view of the case 14 alone, as viewed diagonally from the front left and slightly above, and FIG. 7B is a perspective view of the case 14 alone, as viewed diagonally from the rear left and slightly below. As shown in FIG. 7A, the base 143 is provided with a plurality of through holes 143a and threaded holes 143b in the circumferential direction. The case 14 is fastened to the left end surface of the transmission case 20 by threading bolts that pass through the through holes 143a into threaded holes in the flange portion of the transmission case 20 and by threading bolts that pass through the flange portion of the transmission case 20 into the threaded holes 143b. Note that the base 143 may be provided with only one of the through holes 143a and the threaded holes 143b.

[0029] The case 14 is not provided over the entire circumference about the axis CL1, but is provided by cutting a portion of the case 14 in the circumferential direction. That is, the case 14 has an end face 146 cut by an imaginary plane that passes through a reference line CL2 rearward of the axis CL1 in FIG. 4 and extends in the left-right direction. As shown in FIG. 7B , the end face 146 (shown hatched for convenience) is located radially outward from the bearing support portion 141, and a portion of the base portion 143, the side wall portion 145, and the flange portion 144 are each cut through the end face 146. A plurality of screw holes 146a are formed in the end face 146.

[0030] As shown in Fig. 4, cover 140 is fastened to end surface 146 via bolts 147 that are threaded into screw holes 146a. When cover 140 is fastened to end surface 146 of case 14, it completely surrounds rotating shaft 15 and driven pulleys 161, 171 (Fig. 6). In this way, cover 140 surrounds rotating shaft 15 and driven pulleys 161, 171 integrally with case 14, and cover 140 may be treated as part of the case. That is, case 14 may be treated as a first case (main case), and cover 140 may be treated as a second case (sub-case).

[0031] As shown in Fig. 5, belt 162 extends forward from driven pulley 161, and belt 172 extends rearward from driven pulley 171. As shown in Figs. 7A and 7B, a pair of upper and lower cutouts 148 of a predetermined depth are provided in side wall 145 of case 14 from the left end face of flange 144 to the right in correspondence with the position of belt 162. The depth of cutout 148 corresponds to the width of belt 162. As a result, as shown in Fig. 3, belt 162 passes through case 14 via cutout 148, and belt 162 can be driven without interfering with case 14.

[0032] As shown in FIGS. 7A and 7B , a notch 149 of a predetermined depth is provided in side wall portion 145 of case 14 extending upward from end face 146 to correspond to the position of belt 172. More specifically, notch 149 is located to the right of notch 148, corresponding to belt 172 being located to the right of belt 162 as shown in FIG. 5 . The depth of notch 149 corresponds to the width of belt 172. As a result, as shown in FIG. 3 , belt 172 passes through case 14 through notch 149, and belt 172 can be driven without interfering with case 14. Note that the depth of notch 149 may be made shorter than the width of belt 172, and a notch may be provided in cover 140 ( FIG. 4 ) so as to be continuous with notch 149. Because notch 149 is provided in end face 146 rather than the left end face of flange portion 144, the depth of notch 149 can be made shorter.

[0033] Cover 140 is attached to end face 146 of case 14 after belt 172 has been placed through notch 149. When cover 140 is attached to case 14, the entrance (lower end) of notch 149 is closed by cover 140, and notch 149 becomes a substantially rectangular opening.

[0034] As shown in Fig. 7B, a plurality of screw holes 144a are formed in the left end surface of the flange portion 144. Bolts 181 (Fig. 4) are threaded into these screw holes 144a, thereby fastening the holder 13 to the left end surface of the flange portion 144. Fig. 8 is a perspective view of the holder 13 alone, viewed from the left rear and slightly above. As shown in Fig. 8, the holder 13 has a flange portion 131 and a pair of front and rear motor support portions 132 and 133 that extend forward and rearward from the front and rear ends of the flange portion 131, respectively.

[0035] Like the flange portion 144 of the case 14, the flange portion 131 is formed in a generally arcuate shape centered on the axis CL1, and the right end surface of the flange portion 131 abuts against the left end surface of the flange portion 144. The motor support portions 132 and 133 are each configured in a generally C-shape corresponding to the shape of the outer peripheral surfaces of the motors 11 and 12. The rear motor support portion 133 extends rearward from the periphery of the flange portion 131, while the front motor support portion 132 bulges out to the left of the flange portion 131 to accommodate misalignment of the belts 162 and 172 in the left-right direction.

[0036] A pair of through holes 134 are formed at both ends of the motor support part 132 in the vertical direction, and the motor 11 is fixed to the motor support part 132 by bolts 135 (FIG. 3) inserted into the through holes 134. A pair of through holes 136 are formed at both ends of the motor support part 133 in the vertical direction, and the motor 12 is fixed to the motor support part 133 by bolts 137 (FIG. 3) inserted into the through holes 136.

[0037] A plurality of through holes 131a are formed in the flange portion 131 and the motor support portion 132 overlapping the flange portion 131, corresponding to the positions of the screw holes 144a (FIG. 7B) of the flange portion 144 of the case 14. As shown in FIG. 4, a bracket 18 is attached to the left end surface of the holder 13. FIG. 9 is a perspective view of the bracket 18 alone, as seen from diagonally forward right. As shown in FIG. 9, the bracket 18 has an attachment portion 182 attached to the holder 13, an attachment portion 183 attached to the chassis 204, and an arm portion 184 connecting the attachment portions 182 and 183. The arm portion 184 extends diagonally forward, leftward, and upward from the attachment portion 182.

[0038] The mounting portion 182 is divided into two circumferentially, with the right end surface of one abutting against the left end surface of the flange portion 131 of the holder 13 and the other right end surface abutting against the left end surface of the motor support portion 132. A plurality of through holes 182a are formed in the mounting portion 182 in correspondence with the positions of the through holes 131a of the holder 13. As shown in FIG. 4, bolts 181 inserted through the through holes 182a of the bracket 18 and the through holes 131a of the holder 13 are threaded into the screw holes 144a (FIG. 7B) of the case 14, thereby fixing the bracket 18 and the holder 13 to the case 14 at once.

[0039] FIG. 10 is a cross-sectional view showing the configuration of the connection between the rotating shaft 15 of the drive unit 1 and the transmission 2. For convenience, part of the transmission 2 is shown by a virtual line (two-dot chain line). As shown in FIG. 10, the transmission 2 has an input shaft 23 that extends in the left-right direction coaxially with the rotating shaft 15. Although not shown, not only the input shaft 23 but also an output shaft that extends in the left-right direction parallel to the input shaft 23 is arranged inside the transmission case 20. Multi-stage gears (not shown) are provided on the outer circumferential surface of the input shaft 23, and torque is transmitted from the input shaft 23 to the output shaft by meshing with gears provided on the outer circumferential surface of the output shaft.

[0040] The left end of the input shaft 23 protrudes leftward from the transmission case 20. The input shaft 23 is rotatably supported by the transmission case 20 via a pair of left and right bearings (ball bearings) 25, 26. More specifically, a portion of the input shaft 23 a predetermined length to the right of the left end and the right end of the input shaft 23 are supported by the bearings 25, 26. A cylindrical shaft portion 27 is provided at the left end (tip end) of the input shaft 23, and a shaft portion 28 having a larger diameter than the shaft portion 27 is provided to the right of the shaft portion 27. A spline is formed on the outer peripheral surface of the shaft portion 28.

[0041] A bottomed hole 155 of a predetermined depth and having a substantially cylindrical shape centered on the axis CL1 is provided in the connecting portion 153 at the right end of the rotary shaft 15, extending from the right end face of the rotary shaft 15 to the left. The bottomed hole 155 has a hole portion 156 at the back of the bottomed hole 155 and a hole portion 157 on the right side of the hole portion 156, the hole portion 157 having a larger diameter than the hole portion 156. The diameter of the hole portion 156 is equal to (or nearly equal to) the diameter of the shaft portion 27, and the shaft portion 27 is fitted into the hole portion 156 with no gap (or almost no gap). Splines are formed on the inner peripheral surface of the hole portion 157, and the splines of the hole portion 157 mesh with the splines of the shaft portion 28. This allows torque to be transmitted from the rotary shaft 15 to the input shaft 23.

[0042] The portion where the shaft portion 27 is fitted into the hole portion 156 is called the fitting portion FP. The rotating shaft 15 is supported at two axial locations by the bearing 41 and the fitting portion FT. This makes it possible to suppress deflection (tilting) of the rotating shaft 15 when torque is applied to the rotating shaft 15 without increasing the size of the bearing 41. As a result, the case 14 having the bearing support portion 141 can be configured compactly.

[0043] The small diameter portion 152 of the rotating shaft 15 has a pulley support portion 152A to which a driven pulley 161 is attached, and a pulley support portion 152B to which a driven pulley 171 is attached. A tensile force F1 acts on the pulley support portion 152A in the direction of the arrow (forward) in FIG. 10 via the driven pulley 161 and the belt 162. A tensile force F2 acts on the pulley support portion 152B in the direction of the arrow (rearward) in FIG. 10 via the driven pulley 171 and the belt 172. The directions in which the tensile forces F1 and F2 act are substantially opposite. As a result, the tensile forces F1 and F2 acting on the rotating shaft 15 cancel each other out, and the radial load acting on the bearing 41 can be reduced.

[0044] 5 and 6, the assembly procedure for the drive unit 1 will be described. First, with the bearing 41 attached to the rotating shaft 15, the rotating shaft 15 is inserted from the right into the bearing support portion 141 of the case 14. Then, a circlip 45 is attached to the groove on the inner peripheral surface of the bearing support portion 141, and the rotating shaft 15 is rotatably attached to the case 14. Next, from the left, a washer 42, a driven pulley 171, a collar 43, and a driven pulley 161 are fitted onto the outer peripheral surface of the rotating shaft 15 in this order, and then a bolt 44 is screwed into the threaded hole 154 of the rotating shaft 15 to secure the washer 42, the driven pulley 171, the collar 43, and the driven pulley 161 to the rotating shaft 15. At this time, the belts 162, 172 are looped around the driven pulleys 161, 171 in advance, and the driven pulleys 161, 171 are assembled to the rotary shaft 15 in a state where the belts 162, 172 are taken out to the outside of the case 14 via the notches 148, 149 (FIG. 7B).

[0045] Next, the pair of motors 11, 12 are fixed to the motor support portions 132, 133 (FIG. 8) of the holder 13. Furthermore, the holder 13 is attached to the flange portion 144 (FIG. 7B) of the case 14 using bolts 181 (FIG. 4). At this time, the bracket 18 is also attached at the same time. Next, the belts 162, 172 are looped around the drive pulleys 111, 121 of the motors 11, 12, respectively, and then a predetermined tension is applied to the belts 162, 172. Finally, the cover 140 is attached to the end surface 146 (FIG. 4) of the case 14, completing the assembly of the drive unit 1.

[0046] After the drive unit 1 is assembled, the base 143 of the case 14 is fastened to the left end of the transmission case 20 using a bolt. At this time, the base 143, which has a generally L-shaped cross section, is positioned relative to the transmission 2, so that the input shaft 23 and the rotating shaft 15 can be positioned coaxially with high precision. As a result, the input shaft 23 can be easily fitted into the bottomed hole 155 of the rotating shaft 15.

[0047] According to this embodiment, the following effects can be achieved. (1) Vehicle drive device 100 includes motors 11, 12 that are drive sources for traveling vehicle 200, a transmission 2 having an input shaft 23 to which torque is input, a speed change mechanism 21 that changes the rotation of input shaft 23, and a transmission case 20 that houses input shaft 23 and speed change mechanism 21, a rotating shaft 15 that extends coaxially with input shaft 23 outside transmission case 20 and is connected to input shaft 23, and power transmission units 16, 17 that transmit the torque of motors 11, 12 to rotating shaft 15, respectively (FIGS. 1, 5, 10). Motors 11 and 12 are arranged at approximately symmetrical positions in the radial direction of rotating shaft 15, with rotating shaft 15 as the axis of symmetry (FIG. 4).

[0048] As a result, the torque of the multiple motors 11 and 12 is input to the input shaft 23 of the transmission 2 via the rotating shaft 15. This allows the torque of the rear wheel 202 to be increased without using a large motor, thereby enabling the vehicle drive device 100 to be made more compact. Furthermore, because the multiple motors 11 and 12 are arranged in approximately symmetrical positions across the rotating shaft 15, the tensile forces F1 and F2 acting on the pulley support portions 152A and 152B of the rotating shaft 15 via the belts 162 and 172 are in opposite directions and are offset. This reduces the radial load acting on the rotating shaft 15. Furthermore, when driving wheels using in-wheel motors, for example, the driving force of a single motor drives a single wheel. Therefore, the total driving force of the multiple motors cannot be transmitted to a single wheel, which may result in insufficient driving force being generated when the wheel spins. In this regard, in the present embodiment, the driving forces of the multiple motors 11 and 12 are input to the transmission 2, allowing each wheel to generate sufficient driving force as needed.

[0049] (2) The vehicle drive device 100 further includes a case 14 attached to the transmission case 20 and covering the periphery of the rotary shaft 15, and a single bearing 41 interposed between the case 14 and the rotary shaft 15 to rotatably support the rotary shaft 15 from the case 14 (FIGS. 5 and 6). The power transmission unit 16 includes an endless belt 162 wound between a drive pulley 111, to which the torque of the motor 11 is output, and a pulley support portion 152A (driven pulley 161) of the rotary shaft 15, and the power transmission unit 17 includes an endless belt 172 wound between a drive pulley 121, to which the torque of the motor 12 is output, and a pulley support portion 152B (driven pulley 171) of the rotary shaft 15 (FIGS. 5 and 10). The pulley support portion 152A and the pulley support portion 152B are provided axially spaced apart from each other between the left end of the rotary shaft 15 and the bearing 41 (FIG. 10). As a result, tensile forces F1 and F2 act in opposite directions at two axial locations on the rotating shaft 15 via the belts 162 and 172. This reduces the radial load acting on the bearing 41, allowing the bearing 41 and the case 14 that supports the bearing 41 to be made smaller.

[0050] (3) The transmission 2 further includes a pair of left and right bearings 25, 26 that rotatably support the input shaft 23 (FIG. 10). The right end (fitting portion FP) of the rotating shaft 15 is fitted to the left end of the input shaft 23 so as to be able to transmit torque (FIG. 10). As a result, the rotating shaft 15 is supported at two locations in the left-right direction by the fitting portion FP and the bearing 41, so that runout of the rotating shaft 15 can be suppressed without increasing the size of the bearing 41.

[0051] (4) The vehicle further includes a pair of left and right drive shafts 206 that transmit the torque output from the transmission 2 to the left and right rear wheels 202, and a differential mechanism 3 that transmits the torque output from the transmission 2 to the pair of left and right drive shafts 206 (FIG. 2). The motor 11 and the rotating shaft 15 are disposed in front of the drive shafts 206, and the motor 12 is disposed above the drive shafts 206 (FIG. 4). This positions the vehicle drive device 100 closer to the drive shafts 206, thereby increasing the ground contact load of the rear wheels 202 and improving the tire grip.

[0052] (5) The height of the lower end of the motor 11 from the road surface is approximately the same as the height of the lower end of the differential mechanism 3 from the road surface (FIG. 4). As a result, when one motor 12 is disposed above the drive shaft 206, the other motor 11 can be disposed in a position approximately symmetrical to the motor 12 with the rotation axis 15 as the axis of symmetry, while still ensuring sufficient ground clearance for the motor 11.

[0053] This embodiment can be modified in various ways. Some modified examples will be described below. In the above embodiment, one motor 12 (second electric motor) is arranged above the drive shaft 206, and the other motor 11 (first electric motor) and the rotating shaft 15 are arranged in front of the drive shaft 206, but the first electric motor and the rotating shaft may be arranged behind the drive shaft.

[0054] In the above embodiment, a belt 162 (first belt-shaped member) is looped between the drive pulley 111 (first output part) to which the torque of the motor 11 is output and the driven pulley 161 provided on the pulley support part 152A (first part) of the rotary shaft 15, and a belt 172 (second belt-shaped member) is looped between the drive pulley 121 (second output part) to which the torque of the motor 12 is output and the driven pulley 171 provided on the pulley support part 152B (second part) of the rotary shaft 15. Here, the endless belt-shaped member may be configured by something other than a belt (for example, a chain).

[0055] In the above embodiment, a single bearing 41 that rotatably supports the rotating shaft 15 is interposed between the case 14 (case portion) that covers the periphery of the rotating shaft and the rotating shaft 15, but the configuration of the rotating shaft support portion is not limited to that described above. In the above embodiment, a pair of left and right pulley support portions 152A, 152B is provided between the left end portion (one axial end portion) of the rotating shaft 15 and the bearing 41, but the arrangement of the pulley support portions is not limited to that described above. In the above embodiment, the input shaft 23 of the transmission 2 is rotatably supported from the transmission case 20 via a pair of left and right bearings 25, 26, but the input shaft 23 may be rotatably supported via more input shaft support portions.

[0056] In the above embodiment, the holes 156, 157 of the rotary shaft 15 and the shaft portions 27, 28 of the input shaft 23 are fitted together via splines so as to enable torque transmission. That is, the right end (the other axial end) of the rotary shaft 15 and the left end (one axial end) of the input shaft 23 are joined together with a spigot joint, but the hole may be provided on the input shaft 23 and the shaft may be provided on the rotary shaft 15, and the two may be fitted together. Therefore, the configuration of the fitting portion FP that fits the one axial end of the input shaft 23 and the one axial end of the rotary shaft 15 together is not limited to the above.

[0057] In the above embodiment, the vehicle driving device 100 is mounted on the bottom of the truck chassis 204, and the rear wheels 202 are driven by the vehicle driving device 100, but the configuration of the vehicle on which the vehicle driving device is mounted is not limited to that described above. The vehicle driving device may drive the front wheels of the vehicle instead of the rear wheels. It may also drive both the front and rear wheels. A vehicle may be provided with multiple vehicle driving devices.

[0058] The above description is merely an example, and the present invention is not limited to the above-described embodiment and modifications as long as the features of the present invention are not impaired. One or more of the above-described embodiment and modifications can be arbitrarily combined, and modifications can also be combined with each other. [Explanation of symbols]

[0059] 1 drive unit, 2 transmission, 3 differential mechanism, 11, 12 motor, 14 case, 15 rotating shaft, 16, 17 power transmission part, 20 transmission case, 21 transmission mechanism, 23 input shaft, 25, 26 bearing, 41 bearing, 100 vehicle drive device, 111, 121 driving pulley, 152A, 152B pulley support part, 161, 171 driven pulley, 162, 172 belt, 200 vehicle, 206 drive shaft

Claims

1. a first electric motor and a second electric motor that are drive sources for the vehicle; a transmission including an input shaft to which torque is input, a speed change mechanism that changes the rotation speed of the input shaft, and a transmission case that houses the input shaft and the speed change mechanism; a rotary shaft extending coaxially with the input shaft outside the transmission case and connected to the input shaft; a first power transmission unit that transmits torque of the first electric motor to the rotary shaft; a second power transmission unit that transmits the torque of the second electric motor to the rotary shaft, the first power transmission unit includes an endless first belt-shaped member wound between a first output unit, from which torque of the first electric motor is output, and a first portion of the rotary shaft; the second power transmission unit includes an endless second belt-shaped member wound between a second output unit, from which torque of the second electric motor is output, and a second portion of the rotary shaft; The vehicle drive device, wherein the first electric motor and the second electric motor are disposed at substantially symmetrical positions with the rotation axis as an axis of symmetry.

2. 2. The vehicle drive device according to claim 1, a case portion attached to the transmission case and covering the periphery of the rotary shaft; a single rotating shaft support portion interposed between the case portion and the rotating shaft and supporting the rotating shaft rotatably from the case portion, The vehicle drive device, wherein the first portion and the second portion are provided between one axial end of the rotating shaft and the rotating shaft support portion and spaced apart from each other in the axial direction.

3. 3. The vehicle drive device according to claim 2, The transmission further includes a plurality of input shaft support portions in the axial direction that rotatably support the input shaft, The vehicle drive device, wherein the other axial end of the rotary shaft is fitted to one axial end of the input shaft so as to be able to transmit torque.

4. 4. The vehicle drive device according to claim 1, a pair of left and right drive shafts that transmit torque output from the transmission to left and right wheels; a differential mechanism that transmits torque output from the transmission to the pair of left and right drive shafts, the first electric motor and the rotating shaft are disposed in front of or behind the drive shaft, The vehicle drive device is characterized in that the second electric motor is disposed above the drive shaft.

5. 5. The vehicle drive device according to claim 4, The vehicle drive device according to claim 1, wherein the first electric motor is disposed so that the height of the lower end thereof from the road surface is substantially the same as the height of the lower end of the differential mechanism from the road surface.

6. In the vehicle drive device according to claim 1, a case portion attached to the transmission case and covering the periphery of the rotary shaft; a holder attached to an end of the case portion and supporting the first electric motor and the second electric motor, The holder is an attachment portion attached to an end portion of the case portion; a first electric motor support portion extending radially from the mounting portion toward one side and supporting the first electric motor; a second electric motor support portion extending radially from the mounting portion toward the other side and supporting the second electric motor.

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