Vehicle drive device

Abstract

To provide a vehicle drive device capable of reducing an axial dimension of a first drive unit in a configuration capable of achieving various modes.SOLUTION: The engine, the second electric motor, the planetary gear device, and the counter drive gear are disposed on a first axis parallel to the counter driven shaft. The first electric motor is disposed on a second axis parallel to the first axis and is coupled to the first rotating element via a power transmission member. This makes it possible to reduce the axial dimension of the first drive unit. The counter drive gear is disposed on the engine side with respect to the planetary gear device. Thus, the axial dimension of the first drive unit can be reduced as compared to the case where the counter drive gear is disposed on the second electric motor side with respect to the planetary gear unit. Therefore, in the vehicle drive device capable of realizing various modes, the axial dimension of the first drive unit can be reduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive device that includes an engine and a drive unit that includes two electric motors and a planetary gear device. [Background technology]

[0002] A well-known vehicle drive system includes an engine, a first drive unit including a planetary gear set having a first electric motor, a second electric motor, and three rotating elements, i.e., a first rotating element, a second rotating element, and a third rotating element, and a first drive shaft that drives one of the front wheels and the rear wheels. For example, a hybrid vehicle drive system is described in Patent Document 1. Patent Document 1 discloses that the axial dimension of the first drive unit is reduced by arranging the input and output shafts of the first electric motor substantially parallel to the input and output shafts of the engine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-80135 Summary of the Invention [Problem to be solved by the invention]

[0004] To realize a variety of drive modes, a possible configuration is one in which the first rotating element of the planetary gear set is connected to an engine and a first electric motor, the second rotating element is connected to a second electric motor, and the third rotating element is connected to a first drive shaft. The drive mode is, for example, a hybrid electric vehicle (HEV) mode in which the engine is operated and power is exchanged between the first electric motor and the second electric motor. The drive mode is, for example, a battery electric vehicle (BEV) mode in which the engine is stopped and torque is generated in the first electric motor and the second electric motor. Even in a vehicle drive system configured in this manner, it is desirable to reduce the axial dimension of the first drive unit. The axial dimension is, for example, the length of the first drive unit in the direction of the first axis, which is the rotational axis of the planetary gear set.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle drive device that can reduce the axial dimension of the first drive unit in a configuration that allows various modes to be realized. [Means for solving the problem]

[0006] The gist of a first invention is a vehicle drive device including: (a) an engine; a first drive unit including a planetary gear set having a first electric motor, a second electric motor, and three rotation elements, i.e., a first rotation element, a second rotation element, and a third rotation element; and a first drive shaft that drives one of front wheels and rear wheels, wherein (b) the first drive unit includes a first gear pair having a counter drive gear and a counter driven gear that meshes with the counter drive gear, a counter driven shaft that is arranged parallel to the first drive shaft and on which the counter driven gear is non-rotatable relative to the counter driven shaft, a final drive gear that is arranged on the counter driven shaft alongside the counter driven gear and is non-rotatable relative to the counter driven shaft, and a final drive gear that meshes with the final drive gear. (c) the first drive unit is configured such that the engine and the first electric motor are connected to the first rotating element, the second electric motor is connected to the second rotating element, and the first drive shaft is connected to the third rotating element via the first gear pair and the second gear pair, (d) the second electric motor, the planetary gear device, and the counter drive gear are arranged in this order from the engine side on a first axis which is a rotational axis of the planetary gear device and is parallel to the counter driven shaft, namely, the counter drive gear, the planetary gear device, and the second electric motor, and (e) the first electric motor is arranged on a second axis which is a rotational axis which is parallel to the first axis, and is connected to the first rotating element via a power transmission member.

[0007] A second invention is a vehicle drive device according to the first invention, wherein the planetary gear device is a double-pinion type planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is one of the carrier and the sun gear, the second rotating element is the other of the carrier and the sun gear, and the third rotating element is the ring gear.

[0008] A third aspect of the present invention is the vehicle drive device according to the second aspect, wherein the first drive unit further includes a bearing that supports the counter drive gear, the sun gear, the ring gear, and the counter drive gear are each helical gears, and the helix angles of the sun gear, the ring gear, and the counter drive gear are set such that the direction of the thrust force generated in the ring gear by the meshing reaction force and the direction of the thrust force generated in the counter drive gear by the meshing reaction force are opposite to each other. Thrust force is synonymous with thrust load.

[0009] Furthermore, a fourth invention is a vehicle drive device described in the third invention, wherein the twist angle of the ring gear is an angle that causes the direction of the thrust force generated in the ring gear by the meshing reaction force to be from the ring gear toward the counter drive gear.

[0010] A fifth invention is a vehicle drive device according to the first invention, wherein the planetary gear device is a double-pinion type planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is the ring gear, the second rotating element is one of the sun gear and the carrier, and the third rotating element is the other of the sun gear and the carrier.

[0011] A sixth invention is a vehicle drive device according to the first invention, wherein the planetary gear device is a single-pinion planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is one of the ring gear and the sun gear, the second rotating element is the other of the ring gear and the sun gear, and the third rotating element is the carrier.

[0012] Furthermore, a seventh invention is a vehicle drive device described in the first invention, wherein the planetary gear device is a single-pinion type planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is the carrier, the second rotating element is one of the sun gear and the ring gear, and the third rotating element is the other of the sun gear and the ring gear.

[0013] An eighth invention is a vehicle drive device according to the seventh invention, wherein the second rotating element is the sun gear, the third rotating element is the ring gear, the first drive unit further includes a bearing supporting the counter drive gear, the sun gear, the ring gear, and the counter drive gear are each helical gears, and the twist angles of the sun gear, the ring gear, and the counter drive gear are such that the direction of the thrust force generated in the ring gear by the meshing reaction force and the direction of the thrust force generated in the counter drive gear by the meshing reaction force are opposite to each other.

[0014] Furthermore, a ninth invention is that in the vehicle drive device described in the first invention, the counter-driven shaft is positioned vertically below a position horizontal to the first axis when mounted on the vehicle.

[0015] Furthermore, a tenth aspect of the present invention is that in the vehicle drive device described in the first aspect of the present invention, the final drive gear is positioned closer to the second electric motor than the counter driven gear in the axial direction of the counter driven gear.

[0016] An eleventh aspect of the present invention is that, in the vehicle drive device described in the first aspect of the present invention, the final driven gear is an input rotating member of a differential gear to which the first drive shaft is connected, and is arranged on the rotational axis of the first drive shaft.

[0017] In addition, a twelfth invention is that in the vehicle drive device described in the first invention, the first drive unit further includes a brake mechanism that stops the rotation of the first rotating element when engaged.

[0018] In addition, a thirteenth aspect of the present invention is a vehicle drive device according to any one of the first to twelfth aspects of the present invention, further comprising a second drive shaft that drives the other of the front wheels and the rear wheels, and a second drive unit that includes a third electric motor connected to the second drive shaft. [Effects of the Invention]

[0019] According to the first aspect of the present invention, the planetary gear device of the first drive unit has an engine and a first electric motor connected to a first rotating element, a second electric motor connected to a second rotating element, and a first drive shaft connected to a third rotating element via a first gear pair and a second gear pair. This allows the vehicle drive system to realize a variety of drive modes. The second electric motor, the planetary gear device, and the counter drive gear are arranged on a first axis parallel to the counter driven shaft. The first electric motor is arranged on a second axis parallel to the first axis and is connected to the first rotating element via a power transmission member. This allows the axial dimension of the first drive unit to be reduced. The counter drive gear is arranged on the engine side relative to the planetary gear device. This allows the axial dimension of the first drive unit to be reduced compared to a system in which the counter drive gear is arranged on the second electric motor side relative to the planetary gear device. Therefore, the axial dimension of the first drive unit can be reduced in a vehicle drive system that allows a variety of drive modes to be realized.

[0020] According to the second aspect of the present invention, the planetary gear set is a double-pinion type, the first rotating element is one of the carrier and the sun gear, the second rotating element is the other of the carrier and the sun gear, and the third rotating element is a ring gear. This allows the axial dimension of the first drive unit to be reduced when the mechanical point at which the rotational speed of the second rotating element, i.e., the rotational speed of the second electric motor, is set to zero using a reduction ratio. Furthermore, connecting the first drive shaft to the third rotating element via the first gear pair and the second gear pair allows for a simpler configuration, thereby reducing the size of the first drive unit.

[0021] According to the third aspect of the present invention, the first drive unit further includes a bearing supporting the counter drive gear. The sun gear, the ring gear, and the counter drive gear are each helical gears. The helix angles of the sun gear, the ring gear, and the counter drive gear are set such that the direction of the thrust force generated in the ring gear by the meshing reaction force is opposite to the direction of the thrust force generated in the counter drive gear by the meshing reaction force. This cancels out at least a portion of the thrust force generated in the ring gear and the thrust force generated in the counter drive gear, thereby reducing the input load to the bearing supporting the counter drive gear. This allows for smaller bearings and lower loss.

[0022] According to the fourth aspect of the present invention, the helix angle of the ring gear is set to an angle that causes the direction of the thrust force generated in the ring gear by the meshing reaction force to be directed from the ring gear toward the counter drive gear, thereby causing the direction of the thrust force generated in the sun gear by the meshing reaction force to be opposite to the direction toward the bearing, thereby effectively reducing the input load to the bearing that supports the counter drive gear.

[0023] According to the fifth aspect of the present invention, the planetary gear set is a double pinion type, the first rotating element is a ring gear, the second rotating element is one of a sun gear and a carrier, and the third rotating element is the other of the sun gear and the carrier. This makes it possible to reduce the axial dimension of the first drive unit when the mechanical point at which the rotational speed of the second rotating element in the planetary gear set, i.e., the rotational speed of the second electric motor, is set to zero, is set using a speed-up ratio.

[0024] According to the sixth aspect of the present invention, the planetary gear set is a single-pinion type, the first rotating element is one of a ring gear and a sun gear, the second rotating element is the other of the ring gear and the sun gear, and the third rotating element is a carrier. This makes it possible to reduce the axial dimension of the first drive unit when the mechanical point at which the rotational speed of the second rotating element in the planetary gear set, i.e., the rotational speed of the second electric motor, is set to zero using a reduction ratio.

[0025] According to the seventh aspect of the present invention, the planetary gear set is a single-pinion type, the first rotating element is a carrier, the second rotating element is one of a sun gear and a ring gear, and the third rotating element is the other of the sun gear and the ring gear. This allows the axial dimension of the first drive unit to be reduced when the mechanical point at which the rotational speed of the second rotating element, i.e., the rotational speed of the second electric motor, is set to zero using a speed-up ratio. Furthermore, connecting the first drive shaft to the third rotating element via the first gear pair and the second gear pair allows for a simpler configuration, thereby reducing the size of the first drive unit.

[0026] According to the eighth aspect of the present invention, the second rotating element is the sun gear, and the third rotating element is the ring gear. The first drive unit further includes a bearing supporting the counter drive gear. The sun gear, the ring gear, and the counter drive gear are each helical gears. The helix angles of the sun gear, the ring gear, and the counter drive gear are such that the direction of the thrust force generated in the ring gear by the meshing reaction force is opposite to the direction of the thrust force generated in the counter drive gear by the meshing reaction force. This cancels out at least a portion of the thrust force generated in the ring gear and the thrust force generated in the counter drive gear, thereby reducing the input load to the bearing supporting the counter drive gear. This allows for smaller bearings and lower loss.

[0027] According to the ninth aspect of the present invention, the counter driven shaft is disposed vertically below a position horizontal to the first axis when mounted on the vehicle, which allows the second axis to be closer to the first drive shaft when mounted on the vehicle, thereby reducing the size of the vehicle drive device.

[0028] According to the tenth aspect of the present invention, the final drive gear is positioned closer to the second electric motor than the counter driven gear in the axial direction of the counter driven gear. As a result, the counter drive gear is positioned closer to the engine than the planetary gear device, which makes it possible to appropriately reduce the axial dimension of the first drive unit.

[0029] According to the eleventh aspect of the present invention, the final driven gear is an input rotation member of a differential gear to which the first drive shaft is connected. As a result, the counter drive gear is disposed closer to the engine than the planetary gear device, thereby making it possible to appropriately shorten the axial dimension of the first drive unit.

[0030] According to the twelfth aspect of the present invention, the first drive unit further includes a brake mechanism that stops rotation of the first rotating element. This allows the vehicle drive device to realize a variety of drive modes, including a mode in which the vehicle can run using the second electric motor as a power source while the engine is stopped, i.e., BEV running.

[0031] According to the thirteenth aspect of the present invention, a third electric motor is coupled to the second drive shaft. This allows the vehicle drive system to realize a variety of drive modes, including a mode that allows so-called series running. For example, when running the vehicle with the engine running, the first electric motor is operated as a generator using engine power, and the generated power is used to operate the third electric motor as a prime mover to drive the second drive shaft, thereby enabling series running. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle equipped with a vehicle drive device (double pinion U / D type) to which the present invention is applied. [Figure 2] FIG. 2 is a nomographic diagram illustrating the configuration of the vehicle drive device. [Figure 3] FIG. 4 is a collinear diagram illustrating a BEV mode in which torque is generated in the first electric motor and the second electric motor. [Figure 4] FIG. 10 is a collinear diagram illustrating a BEV mode in which torque is generated by the second electric motor with the brake engaged. [Figure 5] FIG. 10 is a collinear diagram illustrating a BEV mode in which torque is generated by the third electric motor with the brakes engaged. [Figure 6] 1A and 1B are nomographic diagrams illustrating a first HEV mode (series mode) in which the engine is driven to rotate and power is exchanged between the first electric motor and the third electric motor. (a) is a nomographic diagram illustrating a case in which torque is generated in the third electric motor by the electric power generated by the first electric motor. (b) is a nomographic diagram illustrating a case in which the electric power generated by the third electric motor is consumed by the power running of the first electric motor to apply engine braking. [Figure 7] 10A and 10B are nomographic diagrams illustrating a second HEV mode (input split mode) in which the engine is operated and power is exchanged between the second electric motor and the third electric motor. (a) is a nomographic diagram illustrating a case in which torque is generated in the third electric motor by the electric power generated by the second electric motor. (b) is a nomographic diagram illustrating a case in which torque is generated in the second electric motor by the electric power generated by the third electric motor. [Figure 8] 10A and 10B are nomographic diagrams illustrating a third HEV mode (output split mode) in which the engine is operated and power is exchanged between the first and second electric motors. (a) is a nomographic diagram illustrating a case in which torque is generated in the second electric motor by the power generated by the first electric motor. (b) is a nomographic diagram illustrating a case in which torque is generated in the first electric motor by the power generated by the second electric motor. [Figure 9] 1A is a diagram illustrating an example of the arrangement of each component of a front drive device according to the present embodiment, and FIG. 1B is a diagram illustrating an example of the arrangement of each component of a front drive device according to a comparative example. [Figure 10] 1 is a diagram illustrating a schematic configuration of a vehicle equipped with a vehicle drive device (double pinion O / D type) to which the present invention is applied, the diagram illustrating a vehicle different from the vehicle of FIG. [Figure 11] 11 is a nomographic diagram showing the configuration of the vehicle drive device of FIG. 10. FIG. [Figure 12] 1 is a diagram illustrating a schematic configuration of a vehicle equipped with a vehicle drive device (single pinion U / D type) to which the present invention is applied, and is a diagram illustrating a vehicle different from the vehicle of FIG. [Figure 13] 13 is a nomographic diagram showing the configuration of the vehicle drive device of FIG. 12. FIG. [Figure 14] 1 is a diagram illustrating a schematic configuration of a vehicle equipped with a vehicle drive device (single pinion O / D type) to which the present invention is applied, and is a diagram illustrating a vehicle different from the vehicle of FIG. [Figure 15] 15 is a nomographic diagram illustrating the configuration of the vehicle drive device of FIG. 14. FIG. [Figure 16]2 is a nomographic diagram showing the configuration of a vehicle drive device different from the vehicle drive device of FIG. 1. FIG. [Figure 17] FIG. 10 is a nomographic diagram illustrating a BEV mode in which torque is generated in the second electric motor with the one-way clutch engaged. [Figure 18] 2 is a diagram illustrating the setting of the torsion angles of the ring gear and counter drive gear of the differential mechanism in the configuration of the vehicle drive device of FIG. 1. FIG. [Figure 19] 15 is a diagram for explaining the setting of the torsion angles of the ring gear and counter drive gear of the differential mechanism in the configuration of the vehicle drive device of FIG. 14. FIG. [Figure 20] FIG. 1 is a diagram illustrating a schematic configuration of a vehicle equipped with a vehicle drive device (double pinion U / D type) of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0034] FIG. 1 is a diagram illustrating a schematic configuration of a vehicle 8 equipped with a vehicle drive system 10 to which the present invention is applied. In FIG. 1, the vehicle 8 is equipped with drive wheels 12 and a vehicle drive system 10 that drives the drive wheels 12. The drive wheels 12 include left and right front wheels 12f and left and right rear wheels 12r. The vehicle drive system 10 includes a front drive system 10f that drives the front wheels 12f and a rear drive system 10r that drives the rear wheels 12r. The vehicle drive system 10 is equipped with a drive shaft 14 that drives the drive wheels 12 and a drive unit 16 that drives the drive shaft 14. The drive shaft 14 includes left and right front drive shafts 14f and left and right rear drive shafts 14r. The drive unit 16 includes a front drive unit 16f and a rear drive unit 16r. Note that the above "left and right" refer to left and right with respect to the forward direction of the vehicle 8.

[0035] The front drive system 10f includes an engine 18, a front drive shaft 14f, and a front drive unit 16f. The rear drive system 10r includes a rear drive shaft 14r and a rear drive unit 16r. The front drive shaft 14f is a first drive shaft of the present invention that drives the front wheels 12f, which are one of the front wheels 12f and the rear wheels 12r. The rear drive shaft 14r is a second drive shaft of the present invention that drives the rear wheels 12r, which are the other of the front wheels 12f and the rear wheels 12r. The front drive unit 16f is a first drive unit of the present invention that drives the front drive shaft 14f. The rear drive unit 16r is a second drive unit of the present invention that drives the rear drive shaft 14r.

[0036] The front drive unit 16f includes a first electric motor MG1, a second electric motor MG2, a front power transmission mechanism 20, an input shaft 22, and a differential mechanism 24. The rear drive unit 16r includes a third electric motor MG3 and a rear power transmission mechanism 50.

[0037] The vehicle 8 is a hybrid vehicle (HEV (Hybrid Electric Vehicle)) or a plug-in hybrid vehicle (PHEV (Plug-in Hybrid Electric Vehicle)). The vehicle 8 is also an all-wheel drive vehicle capable of independently driving the front wheels 12f and the rear wheels 12r. All-wheel drive (AWD) and four-wheel drive (4WD) are synonymous. The vehicle drive system 10 is capable of front-wheel drive, in which torque is transmitted only to the front wheels 12f, and rear-wheel drive, in which torque is transmitted only to the rear wheels 12r.

[0038] The engine 18 is, for example, a known internal combustion engine. An electronic control unit 70 (described later) controls an engine control device 60, thereby controlling the engine torque Te of the engine 18. The engine control device 60 is provided in the front drive unit 10f and includes a throttle actuator, a fuel injection device, an ignition device, etc.

[0039] The first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 are rotating electric machines, so-called motor generators, that function as a prime mover that generates mechanical power from electric power and as a generator that generates electric power from mechanical power. The first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 are each connected to a battery 64 provided in the vehicle drive system 10 via an inverter 62 provided in the vehicle drive system 10. The torque of the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 is controlled by an electronic control device 70 (described later) controlling the inverter 62. The torque of the first electric motor MG1 is first electric motor torque Tmg1, the torque of the second electric motor MG2 is second electric motor torque Tmg2, and the torque of the third electric motor MG3 is third electric motor torque Tmg3. The torque of the electric motors is power running torque when the electric motors function as prime movers, and is regenerative torque when the electric motors function as generators. The battery 64 is an electricity storage device that supplies and receives electric power to and from each of the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3. The first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 are controlled via the inverter 62 so that electric power is supplied and received simultaneously. "Simultaneously" means, for example, that the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 are each capable of power running or regenerating independently and simultaneously.

[0040] The front power transmission mechanism 20 is a first power transmission mechanism provided in a power transmission path between the differential mechanism 24 and the front drive shaft 14f, i.e., the front wheels 12f. The front power transmission mechanism 20 includes a counter gear pair 26, a counter driven shaft 28, a final gear pair 30, a front differential gear 32, etc.

[0041] The input shaft 22 is a rotating member that connects the engine 18 and the differential mechanism 24. The counter gear pair 26 is a first gear pair of the present invention, having a counter drive gear 34 and a counter driven gear 36 that meshes with the counter drive gear 34. The final gear pair 30 is a second gear pair of the present invention, having a final drive gear 38 and a final driven gear 32r that meshes with the final drive gear 38. The counter driven shaft 28 is a rotating shaft that is arranged parallel to the front drive shaft 14f. The counter driven gear 36 and the final drive gear 38 are mounted on the counter driven shaft 28 so that they cannot rotate relative to each other. The counter driven gear 36 and the final drive gear 38 are arranged side by side on the counter driven shaft 28. The final drive gear 38 has a smaller diameter than the counter driven gear 36. The final driven gear 32r is a ring gear of the front differential gear 32 and functions as an input rotation member of the front differential gear 32 of the present invention. The front differential gear 32 is the differential gear of the present invention to which the front drive shaft 14f is connected. The differential mechanism 24 and the front drive shaft 14f are connected via the front power transmission mechanism 20 and the like.

[0042] The differential mechanism 24 is a double-pinion planetary gear device of the present invention that has a sun gear S, pinions Pa and Pb, a carrier C, and a ring gear R. The carrier C supports the pinions Pa and Pb so that they can rotate and revolve. The ring gear R meshes with the sun gear S via the pinions Pa and Pb. The pinions Pa and Pb are multiple pairs of pinions that mesh with each other. A second electric motor MG2 is connected to the sun gear S. An engine 18 and a first electric motor MG1 are connected to the carrier C. A front drive shaft 14f is connected to the ring gear R via a counter gear pair 26, a final gear pair 30, etc.

[0043] The engine 18, second electric motor MG2, differential mechanism 24, and counter drive gear 34 are each disposed on a first axis CS1, which is the rotational axis of the differential mechanism 24. The first axis CS1 is a rotational axis parallel to the counter driven shaft 28. The first electric motor MG1 is disposed on a second axis CS2, which is a rotational axis parallel to the first axis CS1. The counter driven gear 36 and final drive gear 38 are each disposed on a third axis CS3, which is the rotational axis of the counter driven shaft 28. The front differential gear 32 and front drive shaft 14f are each disposed on a fourth axis CS4, which is the rotational axis of the front drive shaft 14f.

[0044] The engine 18 is connected to the carrier C of the differential mechanism 24 via the input shaft 22. The first electric motor MG1 is disposed on a second axis CS2 that is different from the first axis CS1. For this reason, the front drive unit 16f further includes a power transmission member 40. The first electric motor MG1 is connected to the carrier C via the power transmission member 40. Part or all of the first electric motor MG1 is disposed in a position that overlaps with the range on the first axis CS1 from the position where the engine 18 is disposed to the position where the second electric motor MG2 is disposed, when viewed radially from the first axis CS1.

[0045] The power transmission member 40 includes, for example, a first intermediate gear 40a fixed to the rotor shaft MG1rs of the first electric motor MG1 so as not to rotate relative to it, a second intermediate gear 40b connected to the carrier C, and a belt 40c connecting the first intermediate gear 40a and the second intermediate gear 40b. The first intermediate gear 40a has a smaller diameter than the second intermediate gear 40b, and the power transmission member 40 functions as, for example, a reduction mechanism. By arranging the first electric motor MG1 on the second axis CS2, the size of the front drive device 10f in the direction of the first axis CS1 is reduced compared to when the first electric motor MG1 is arranged on the first axis CS1. In other words, the axial dimension of the front drive unit 16f is reduced.

[0046] The front drive unit 16f further includes a brake BR. One end of the brake BR is connected to the input shaft 22, and the other end is connected to a non-rotating member (not shown). The non-rotating member to which the brake BR is connected is, for example, a case that houses the front drive unit 16f and the like (see the front case 90 in FIG. 18, which will be described later). The brake BR is an engagement device that is actuated by, for example, an electric or hydraulic actuator to selectively connect the members at both ends. The brake BR functions as a brake mechanism that selectively stops the rotation of the input shaft 22. The carrier C, which is connected to the input shaft 22, is selectively made non-rotatable or rotatable by the brake BR.

[0047] The rear power transmission mechanism 50 is a second power transmission mechanism provided in the power transmission path between the third electric motor MG3 and the rear drive shaft 14r, i.e., the rear wheels 12r. The rear power transmission mechanism 50 includes an output gear 52, a rear counter gear 54, a rear differential gear 56, and the like. The output gear 52 is fixed to the rotor shaft MG3rs of the third electric motor MG3 so as not to rotate relative to the rotor shaft MG3rs, and is in mesh with the rear counter gear 54. The output gear 52 and the rear differential gear 56 are connected via the rear counter gear 54. The rear differential gear 56 is a differential gear to which the rear drive shaft 14r is connected. The third electric motor MG3 is connected to the rear drive shaft 14r via the rear power transmission mechanism 50 and the like. The output gear 52 has a smaller diameter than the rear counter gear 54, and the output gear 52 and the rear counter gear 54 function as, for example, a reduction mechanism.

[0048] The rear drive unit 16r further includes a parking mechanism PLC. One end of the parking mechanism PLC is connected to a non-rotating member (not shown). The parking mechanism PLC is operated by, for example, an electric actuator or a manually operated mechanical actuator, and the other end of the parking mechanism PLC is engaged with or disengaged from the output gear 52. The non-rotating member to which the parking mechanism PLC is connected is, for example, a case that houses the rear drive unit 16r and the like. The parking mechanism PLC is a known parking lock device that switches between a parking lock state in which the output gear 52 is mechanically fixed so as to be non-rotatable, and a non-parking lock state in which the output gear 52 is rotatable. The output gear 52 is a rotating member that rotates together with the rear drive shaft 14r. The output gear 52 and the rear drive shaft 14r are selectively non-rotatable or rotatable by the parking mechanism PLC.

[0049] The vehicle drive system 10 further includes an electronic control unit 70 as a controller including control devices related to the control of the vehicle drive system 10 and the like. The electronic control unit 70 includes, for example, a so-called microcomputer equipped with a CPU, RAM, ROM, an input / output interface, and the like. The CPU performs various controls of the vehicle 8 by, for example, performing signal processing according to a program stored in the ROM in advance. For example, the electronic control unit 70 controls the outputs of the engine 18, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3, and performs drive mode switching control, which will be described later. The electronic control unit 70 is configured to be divided into units for overall control, engine control, electric motor control, etc., as necessary.

[0050] Various signals based on detection signals from various sensors provided in the vehicle 8 are input to the electronic control device 70. The various signals include, for example, the engine speed Ne, the vehicle speed V, the first electric motor rotation speed Nmg1, the second electric motor rotation speed Nmg2, the third electric motor rotation speed Nmg3, the accelerator opening θacc, the operation position POSop, and the charge level SOC. The operation position POSop is, for example, the lever position of the shift operation device, such as "P," "R," "N," or "D." The charge level SOC [%] is the remaining charge of the battery 64, calculated based on, for example, the battery charge / discharge current and the battery voltage.

[0051] The electronic control device 70 outputs various command signals to various devices (e.g., engine control device 60, inverter 62, brake BR, etc.) provided in the vehicle 8. The various command signals include, for example, an engine control command signal Se, a first electric motor control command signal Smg1, a second electric motor control command signal Smg2, a third electric motor control command signal Smg3, and a brake control command signal Sbr. The engine control command signal Se is a command signal for controlling the intake amount, ignition timing, fuel injection amount, etc., for controlling the engine 18. The first electric motor control command signal Smg1 is a command signal for controlling the first electric motor MG1, for example, a first electric motor current, etc. The second electric motor control command signal Smg2 is a command signal for controlling the second electric motor MG2, for example, a second electric motor current, etc. The third electric motor control command signal Smg3 is a command signal for controlling the third electric motor MG3, for example, a third electric motor current, etc. The brake control command signal Sbr is a request signal for controlling the brake BR to an ON state or an OFF state. Note that, in an engagement device, the ON state is synonymous with an engaged state (= connected state), and the OFF state is synonymous with a released state (= disconnected state).

[0052] FIG. 2 is a nomographic diagram showing the configuration of the vehicle drive system 10. In FIG. 2, the rear drive system 10r is a main unit that is used for driving with priority over, for example, the front drive system 10f. In this case, the front drive system 10f is considered an auxiliary unit. "FrOUT" in FIG. 2 indicates the front wheels 12f, and "RrOUT" in FIG. 2 indicates the rear wheels 12r.

[0053] The differential mechanism 24 of the front drive unit 10f has three rotating elements: a first rotating element RE1, a second rotating element RE2, and a third rotating element RE3. Each of the rotating elements RE1-RE3 of the differential mechanism 24 is connected to an actuator. The nomographic diagram of FIG. 2 illustrates the three rotating elements of the differential mechanism 24 arranged in a straight line. Expressed using the nomographic diagram, the first rotating element RE1 is the carrier C. The engine 18 and the first electric motor MG1 are connected to the first rotating element RE1. The second rotating element RE2 is the sun gear S. The second electric motor MG2 is connected to the second rotating element RE2. The third rotating element RE3 is the ring gear R. The front drive shaft 14f, i.e., the front wheels 12f, are connected to the third rotating element RE3 via a counter gear pair 26, a final gear pair 30, and the like. The brake BR is a brake mechanism of the present invention that stops rotation of the first rotating element RE1 when engaged.

[0054] The third electric motor MG3 of the rear drive unit 10r is connected to the rear wheels 12r, and can therefore be considered to be connected to the front wheels 12f via the ground (see dashed lines). By controlling the first electric motor MG1, second electric motor MG2, and third electric motor MG3 so that electric power is exchanged simultaneously, it is possible to travel as if the third electric motor MG3 were connected to the front wheels 12f.

[0055] The electronic control device 70 controls the engine 18, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3, and is capable of switching the drive mode to one of a plurality of modes.

[0056] Here, the multiple modes into which the drive mode of the vehicle 8 can be switched will be described with reference to FIGS. 3 to 8. FIGS. 3 to 8 each show the relative rotational speeds of the rotational elements RE1-RE3 of the differential mechanism 24 in the alignment chart of FIG. 2. In this alignment chart, vertical lines Y1-Y3 are arranged in the order of Y1, Y2, and Y3 from the left side of the drawing. The vertical line Y1 represents the rotational speed of the sun gear S, which is the second rotational element RE2 connected to the second electric motor MG2. The vertical line Y2 represents the rotational speed of the ring gear R, which is the third rotational element RE3 connected to the front wheels 12f (see "FrOUT" in the drawing). The vertical line Y3 represents the rotational speed of the carrier C, which is the first rotational element RE1 connected to the engine 18 (see "ENG" in the drawing) and the first electric motor MG1. Furthermore, this indicates that the third electric motor MG3 connected to the rear wheels 12r (see "RrOUT" in the drawing) is connected to the front wheels 12f via the ground. Each arrow indicates the magnitude and direction of torque converted onto the axis of each rotating element RE1-RE3. The solid arrow indicates the torque output from each actuator, and the dashed arrow indicates the mechanically transmitted torque.

[0057] FIG. 3 is a nomographic diagram illustrating Mode1_MG2, a BEV mode in which torque is generated in the first electric motor MG1 and the second electric motor MG2, which is one of Mode1 modes that enables BEV driving. In FIG. 3, Mode1_MG2 is included in multiple modes that allow switching of the drive mode. Mode1_MG2 is a mode in which the engine 18 is stopped and torque is generated in the first electric motor MG1 and the second electric motor MG2, thereby enabling BEV driving. In Mode1_MG2, the first electric motor MG1 and the second electric motor MG2 exchange power with the battery 64 and generate mutual torque so that the moment around the third rotating element RE3 becomes zero, thereby enabling BEV driving. At this time, the first electric motor torque Tmg1 is controlled, for example, so as not to cause drag of the engine 18, i.e., so that the rotational speed of the first rotating element RE1 becomes zero. In Mode1_MG2, the differential mechanism 24 is in a differential state, and torque is generated in the first electric motor MG1 and the second electric motor MG2, and the torque is mechanically transmitted to the third rotating element RE3, which is the output element. Note that in Mode1_MG2, it is also possible to increase the drive torque by generating torque in the third electric motor MG3.

[0058] FIG. 4 is a nomographic diagram illustrating Mode1_MG2_BRon, a BEV mode in which torque is generated by the second electric motor MG2 with the brake BR engaged, which is another mode of Mode1 that enables BEV driving. In FIG. 4, Mode1_MG2_BRon is included in multiple modes that allow switching of the drive mode. Mode1_MG2_BRon is a mode in which BEV driving is performed by stopping the engine 18 and generating torque at the second electric motor MG2 with the brake BR engaged. In Mode1_MG2_BRon, the brake BR is engaged and the rotational speed of the first rotating element RE1 is fixed to zero. Therefore, forward and reverse BEV driving is enabled by the second electric motor MG2 using the power of the battery 64 without generating torque at the first electric motor MG1. In this case, BEV driving is enabled with the maximum torque of the second electric motor MG2. In Mode1_MG2_BRon, the differential mechanism 24 is in a non-differential state, and torque is generated in the second electric motor MG2, which mechanically transmits the torque to the third rotating element RE3, which is the output element. Note that in Mode1_MG2_BRon, it is also possible to increase the drive torque by generating torque in the third electric motor MG3.

[0059] FIG. 5 is a nomographic diagram illustrating Mode1_MG3, a BEV mode in which torque is generated by the third electric motor MG3 with the brake BR engaged, which is yet another mode within Mode1 that enables BEV driving. In FIG. 5, Mode1_MG3 is included in multiple modes that allow switching of the drive mode. Mode1_MG3 is a mode in which the engine 18 is stopped and torque is generated by the third electric motor MG3 with the brake BR engaged, thereby achieving BEV driving. In Mode1_MG3, the brake BR is engaged and the rotational speed of the first rotating element RE1 is fixed to zero. This prevents drag from the engine 18 or the first electric motor MG1, and enables forward and reverse BEV driving by the third electric motor MG3 using the power of the battery 64.

[0060] In Mode1_MG3, it is also possible to increase the drive torque by causing the second electric motor MG2 to generate torque. Also, in Mode1_MG3, it is possible to perform BEV running by causing the third electric motor MG3 to generate torque even if the brake BR is not engaged. In other words, Mode1_MG3 may be a mode in which the engine 18 is stopped and the third electric motor MG3 is caused to generate torque to perform BEV running.

[0061] FIG. 6 is a nomographic diagram illustrating a first HEV mode, or Mode 2, in which the engine 18 is rotationally driven and power is exchanged between the first electric motor MG1 and the third electric motor MG3. FIG. 6(a) is a nomographic diagram when torque is generated in the third electric motor MG3 by the electric power generated by the first electric motor MG1. FIG. 6(b) is a nomographic diagram when engine braking is applied by consuming the electric power generated by the third electric motor MG3 through the power running of the first electric motor MG1. In FIG. 6, Mode 2 is included in multiple modes that allow switching of the drive mode. Mode 2 is a mode in which hybrid driving, or HEV driving, is possible, and is a series mode in which series driving using the engine 18 as a power source is possible.

[0062] In FIG. 6A, Mode 2 includes a mode in which the engine 18 is operated to operate the first electric motor MG1 as a generator while the third electric motor MG3 is operated as a prime mover using the generated electric power of the first electric motor MG1. Mode 2 is a mode in which, with the brake BR disengaged, an electric continuously variable transmission function can be realized, performing series mode operation with the engine 18 as the input and the rear wheels 12r as the output. In Mode 2, the power of the engine 18 is converted via the first electric motor MG1, and the generated electric power of the first electric motor MG1 is converted via the third electric motor MG3. The power conversion is between mechanical and electrical power. In Mode 2, explosive vibration torque of the engine 18 is not transmitted to the front driveshaft 14f, which is advantageous for suppressing NV. "NV" is a general term for noise and vibration, such as booming noise, generated in the vehicle 8, and represents at least one of the noise and vibration in the vehicle 8. Therefore, Mode 2 is useful for use, for example, in low-speed, low-load ranges where quietness is required. Furthermore, in Mode 2, for example, the setting of the operating point of the engine 18 is less subject to restrictions such as muffled noise, so the engine 18 can be operated at an operating point that provides good fuel efficiency.

[0063] In FIG. 6(b), Mode 2 includes a mode in which the third electric motor MG3 is operated as a generator, and the first electric motor MG1 is powered by the electric power generated by the third electric motor MG3 to rotate and drive the engine 18. In Mode 2, the electric power consumed by the power running of the first electric motor MG1 is covered by the regenerative electric power of the third electric motor MG3 generated by the kinetic energy of the vehicle 8, and the engine rotation speed Ne is increased by the power running of the first electric motor MG1. The rotation speed of the engine 18 is increased by the first electric motor torque Tmg1 in a fuel-cut state, and the torque converted onto the shaft of the first rotating element RE1 is negative torque. Note that even when the engine 18 is operated by injecting fuel, if the engine rotation speed Ne is increased by the first electric motor torque Tmg1 to a speed higher than that in the autonomous operation state, the torque converted onto the shaft of the first rotating element RE1 is negative torque. The positive direction of torque is the direction of torque when the engine 18 is operating. The state in which the engine 18 is operating is synonymous with the state in which the engine 18 alone generates positive torque. In Mode 2 of FIG. 6(b), the kinetic energy of the vehicle 8 is converted into power via the third electric motor MG3, and the electric power generated by the third electric motor MG3 is converted into power via the first electric motor MG1. In this way, engine braking can be applied in Mode 2. Even when engine braking is applied in Mode 2, the explosive vibration torque of the engine 18 is not transmitted to the front drive shaft 14f, which is advantageous for suppressing NV.

[0064] FIG. 7 is a nomographic diagram illustrating a second HEV mode, i.e., Mode 3, in which the engine 18 is operated and power is exchanged between the second electric motor MG2 and the third electric motor MG3. (a) of FIG. 7 is a nomographic diagram illustrating a case in which torque is generated in the third electric motor MG3 by the electric power generated by the second electric motor MG2. (b) of FIG. 7 is a nomographic diagram illustrating a case in which torque is generated in the second electric motor MG2 by the electric power generated by the third electric motor MG3. In FIG. 7, Mode 3 is included in multiple modes that allow switching of the drive mode. Mode 3 is a mode that allows hybrid driving, i.e., HEV driving, and is an input split mode that allows input split driving using the engine 18 as a power source. In Mode 3, the differential mechanism 24 is in a differential state, and the second electric motor MG2 takes up the reaction force of the engine torque Te, thereby mechanically transmitting torque to the third rotating element RE3. Mode 3 is a mode in which, with the brake BR released, an electric continuously variable transmission function can be realized that performs input split mode operation with the engine 18 as input and the front wheels 12f and rear wheels 12r as output. In Mode 3, engine braking can be applied. Expressed using a nomographic diagram, input split refers to a type in which two electric motors (MG2, MG3) and one engine are connected to three rotating elements of a differential mechanism, and the electric motor (MG3) is located as the output element (RE3).

[0065] The two-dot chain line A in FIG. 7(a) indicates a state in which a mechanical point is formed in the differential mechanism 24 where no electrical work is performed by setting the rotational speed of the second rotating element RE2 (second electric motor rotational speed Nmg2) to zero and the power of the second electric motor MG2 to zero. At this mechanical point in the differential mechanism 24, the rotational speed of the third rotating element RE3, which is the output element, is on the deceleration side, i.e., the underdrive (U / D) side, relative to the engine rotational speed Ne. In other words, the mechanical point of the differential mechanism 24 is set by the reduction ratio. In FIG. 7, Mode 3 is the U / D input split mode.

[0066] In (a) of Figure 7, Mode 3 includes at least a mode in which the engine 18 is operated to operate the second electric motor MG2 as a generator, while the third electric motor MG3 is operated as a prime mover by the electric power generated by the second electric motor MG2. In Mode 3, torque is mechanically transmitted to the third rotating element RE3, and the electric power generated by the second electric motor MG2 is supplied to the third electric motor MG3, causing the third electric motor MG3 to generate torque. In Mode 3, the power of the engine 18 is converted via the second electric motor MG2, and the electric power generated by the second electric motor MG2 is converted via the third electric motor MG3. Mode 3 has high transmission efficiency in the high load range, and is therefore useful for use in the high load range, for example.

[0067] In (b) of Fig. 7, Mode 3 may include a mode in which the second electric motor MG2 is operated as a prime mover by electric power generated by the third electric motor MG3 while the engine 18 is running. In Mode 3, the second electric motor MG2 is rotated in the forward direction when torque is mechanically transmitted to the third rotating element RE3, and therefore the electric power consumed by the power running of the second electric motor MG2 is covered by regenerative electric power of the third electric motor MG3 that is generated by the kinetic energy of the vehicle 8. In Mode 3 of (b) of Fig. 7, the kinetic energy of the vehicle 8 is converted into power via the third electric motor MG3, and the electric power generated by the third electric motor MG3 is converted into power via the second electric motor MG2.

[0068] The vehicle drive device 10 is controlled to perform Mode 3 shown in Fig. 7(a) during normal driving where the drive mode is switched with emphasis on energy efficiency, for example. On the other hand, when the drive mode is switched with emphasis on power performance, for example, and Mode 3 shown in Fig. 7(a) is not executed, the vehicle drive device 10 is controlled to perform Mode 3 shown in Fig. 7(b).

[0069] FIG. 8 is a nomographic diagram illustrating a third HEV mode, i.e., Mode 4, in which the engine 18 is operated and power is exchanged between the first electric motor MG1 and the second electric motor MG2. (a) of FIG. 8 is a nomographic diagram illustrating a case in which torque is generated in the second electric motor MG2 by the electric power generated by the first electric motor MG1. (b) of FIG. 8 is a nomographic diagram illustrating a case in which torque is generated in the first electric motor MG1 by the electric power generated by the second electric motor MG2. In FIG. 8, Mode 4 is included in a plurality of modes that enable switching of the drive mode. Mode 4 is a mode that enables hybrid driving, i.e., HEV driving, and is an output split mode that enables output split driving using the engine 18 as a power source. In Mode 4, the differential mechanism 24 is in a differential state, and the second electric motor MG2 takes up the reaction force of the engine torque Te, thereby mechanically transmitting torque to the third rotating element RE3. Mode 4 is a mode in which, with the brake BR released, an electric continuously variable transmission function can be realized, in which the input is the engine 18 and the output is the front wheels 12f, performing output split mode operation. In Mode 4, engine braking can be applied. Since the mechanical point of the differential mechanism 24 is set by the reduction ratio, Mode 4 in FIG. 8 is U / D output split mode. Expressed using a collinear diagram, output split refers to a type in which, when two electric motors (MG1, MG2) and one engine are connected to three rotating elements of the differential mechanism, the electric motor (MG1) is located at the input element (RE1) to which the engine is connected.

[0070] In (a) of Fig. 8, Mode 4 includes at least a mode in which the engine 18 is operated to operate the first electric motor MG1 as a generator, while the second electric motor MG2 is operated as a prime mover by the electric power generated by the first electric motor MG1. In Mode 4, when torque is mechanically transmitted to the third rotating element RE3, the second electric motor MG2 is rotated in the forward direction. Therefore, the electric power consumed by the power running of the second electric motor MG2 is covered by the electric power generated by the first electric motor MG1 using the power of the engine 18. In Mode 4, the power of the engine 18 is converted via the first electric motor MG1, and the electric power generated by the first electric motor MG1 is converted via the second electric motor MG2. Mode 4 has high transmission efficiency at high vehicle speeds, and is therefore useful for use at high vehicle speeds, for example.

[0071] In (b) of Fig. 8, Mode 4 may include a mode in which the first electric motor MG1 is operated as a prime mover by the electric power generated by the second electric motor MG2 while the engine 18 is running. In Mode 4, the second electric motor MG2 is rotated in the negative direction when torque is mechanically transmitted to the third rotating element RE3. Therefore, the electric power generated by the second electric motor MG2 is supplied to the first electric motor MG1, causing the first electric motor MG1 to generate torque. In Mode 4 of (b) of Fig. 8, the power of the engine 18 is converted via the second electric motor MG2, and the electric power generated by the second electric motor MG2 is converted via the first electric motor MG1.

[0072] The vehicle drive device 10 is controlled to perform Mode 4 shown in (a) of Fig. 8 during normal driving where the drive mode is switched with emphasis on energy efficiency, for example. On the other hand, when the drive mode is switched with emphasis on power performance, for example, and Mode 4 shown in (a) of Fig. 8 is not executed, the vehicle drive device 10 is controlled to perform Mode 4 shown in (b) of Fig. 8.

[0073] Incidentally, it is desirable to reduce the axial dimension of the front drive unit 16f. FIG. 20 is a diagram illustrating a schematic configuration of a vehicle 500 equipped with a vehicle drive system 510 (including a front drive system 510f and a rear drive system 510r) of a comparative example. In FIG. 20, the coupling relationships of the components in the drive unit 516 (including a front drive unit 516f and a rear drive unit 516r) of the vehicle drive system 510 are the same as those of the drive unit 16 of the vehicle drive system 10. The arrangement of the components in the front drive unit 516f of the front drive system 510f is different from that of the front drive unit 16f of the vehicle drive system 10. In the front drive unit 516f of the comparative example, the second electric motor MG2, the differential mechanism 24, and the counter drive gear 34 are arranged on the first axis CS1 in the order of the differential mechanism 24, the counter drive gear 34, and the second electric motor MG2, from the engine 18 side. Furthermore, the position of the final drive gear 38 in the direction of the counter driven shaft 28, i.e., the direction of the third axis CS3, is located closer to the engine 18 than the counter driven gear 36. On the other hand, the position of the final gear pair 30, which is connected to the front drive shaft 14f via the front differential gear 32, in the direction of the fourth axis CS4, i.e., the vehicle width direction, is physically restricted by the position of the engine 18. Therefore, since the final gear pair 30 (synonymous with the front differential gear 32) cannot be moved closer to the engine 18, the second electric motor MG2, the differential mechanism 24, and the counter drive gear 34 are separated from the engine 18 in the direction of the first axis CS1. As a result, the axial dimension of the front drive unit 516f is increased. Note that the rear drive unit 510r is the same as the rear drive unit 10r, and therefore a description thereof will be omitted.

[0074] Returning to Figure 1, in the front drive unit 16f of this embodiment, the second electric motor MG2, the differential mechanism 24, and the counter drive gear 34 are arranged on the first axis CS1 in the following order from the engine 18 side: counter drive gear 34, differential mechanism 24, and second electric motor MG2. The final drive gear 38 is arranged closer to the second electric motor MG2 than the counter driven gear 36 in the direction of the counter driven shaft 28, i.e., the direction of the third axis CS3.

[0075] Figure 9 is a diagram illustrating an example of the arrangement of the components of the front drive unit 10f. Figure 9(a) is a diagram illustrating an example of the arrangement of the components of the front drive unit 10f of this embodiment. Figure 9(b) is a diagram illustrating an example of the arrangement of the components of a front drive unit 510f of a comparative example.

[0076] In FIG. 9(a), when the front drive unit 10f is mounted on the vehicle 8, the first axle center CS1, the second axle center CS2, the third axle center CS3, and the fourth axle center CS4 are arranged parallel to a horizontal direction perpendicular to the forward / rearward traveling direction of the vehicle 8. The same is true for the front drive unit 510f in FIG. 9(b). As shown in FIG. 9(a), when the front drive unit 10f is mounted on the vehicle 8, the counter-driven shaft 28 of the front drive unit 10f is arranged vertically below a position horizontal to the first axle center CS1. In the front drive unit 10f, the first electric motor MG1, i.e., the second axle center CS2, can be brought closer to the front drive shaft 14f (see arrow B) while avoiding interference between the belt 40c and the counter-driven shaft 28 or the final drive gear 38. This allows the vertical size of the front drive unit 10f to be reduced. 9(b), the counter-driven shaft 28 of the front drive unit 510f is disposed in a position parallel to the first axis CS1 or in a position vertically above the position parallel to the first axis CS1 when the front drive unit 510f is mounted on the vehicle 500. Therefore, in the front drive unit 510f, the first electric motor MG1 needs to be disposed vertically above or forward in the forward / rearward travel direction (see arrow D) to avoid interference between the belt 40c and the counter-driven shaft 28 or the final drive gear 38. This may increase the vertical size of the front drive unit 510f (see vertical height H).

[0077] As described above, according to this embodiment, the differential mechanism 24 has the engine 18 and the first electric motor MG1 connected to the first rotating element RE1, the second electric motor MG2 connected to the second rotating element RE2, and the front drive shaft 14f connected to the third rotating element RE3. This allows the vehicle drive system 10 to realize a variety of drive modes. The second electric motor MG2, the differential mechanism 24, and the counter drive gear 34 are arranged on the first axis CS1 parallel to the counter driven shaft 28. The first electric motor MG1 is arranged on the second axis CS2 parallel to the first axis CS1 and is connected to the first rotating element RE1 via the power transmission member 40. This allows the axial dimension of the front drive unit 16f to be shortened. The counter drive gear 34 is arranged on the engine 18 side of the differential mechanism 24. This allows the axial dimension of the front drive unit 16f to be shorter than in a case where the counter drive gear 34 is disposed closer to the second electric motor MG2 than the differential mechanism 24 (see FIG. 20). Therefore, in the vehicle drive system 10 that can realize a variety of modes, the axial dimension of the front drive unit 16f can be reduced.

[0078] Furthermore, according to this embodiment, the differential mechanism 24 is a double-pinion planetary gear device, with the first rotating element RE1 being the carrier C, the second rotating element RE2 being the sun gear S, and the third rotating element RE3 being the ring gear R. This makes it possible to shorten the axial dimension of the front drive unit 16f when setting the mechanical point by the reduction ratio in the differential mechanism 24. Furthermore, when connecting the front drive shaft 14f to the third rotating element RE3 via the counter gear pair 26, the final gear pair 30, etc., the configuration can be simplified, and the physical size of the front drive unit 16f can be reduced.

[0079] Furthermore, according to this embodiment, the counter driven shaft 28 is disposed in a position vertically lower than a position horizontal to the first axis CS1 when mounted on the vehicle 8. This allows the second axis CS2 to be closer to the front drive shaft 14f when mounted on the vehicle 8, thereby reducing the size of the vehicle drive device 10.

[0080] Furthermore, according to this embodiment, the final drive gear 38 is positioned closer to the second electric motor MG2 in the direction of the counter driven shaft 28 than the counter driven gear 36. As a result, the counter drive gear 34 is positioned closer to the engine 18 than the differential mechanism 24, which makes it possible to appropriately shorten the axial dimension of the front drive unit 16f.

[0081] Furthermore, according to this embodiment, the final driven gear 32r is an input rotating member of the front differential gear 32 to which the front drive shaft 14f is connected. As a result, the counter drive gear 34 is disposed closer to the engine 18 than the differential mechanism 24, thereby making it possible to appropriately shorten the axial dimension of the front drive unit 16f.

[0082] Furthermore, according to this embodiment, the front drive unit 16f further includes a brake BR that stops the rotation of the first rotating element RE1. This allows the vehicle drive system 10 to realize a variety of drive modes, including a mode in which the vehicle can run as a BEV, using the second electric motor MG2 as a power source, with the engine 18 stopped.

[0083] Furthermore, according to this embodiment, the third electric motor MG3 is coupled to the rear drive shaft 14r. This allows the vehicle drive system 10 to realize a variety of drive modes, including a mode in which so-called series running can be performed. For example, when running the vehicle 8 with the engine 18 running, the first electric motor MG1 is operated as a generator, and the third electric motor MG3 is operated as a prime mover with the generated electric power to drive the rear drive shaft 14r, thereby enabling series running.

[0084] Next, another embodiment of the present invention will be described. In the following description, parts common to the embodiments will be given the same reference numerals and the description thereof will be omitted. [Example]

[0085] FIG. 10 is a diagram illustrating the schematic configuration of a vehicle 100 equipped with a vehicle drive system 110 (including a front drive system 110f and a rear drive system 110r) to which the present invention is applied. In FIG. 10, the vehicle drive system 110 includes a drive shaft 14 that drives the drive wheels 12 and a drive unit 116 (including a front drive unit 116f and a rear drive unit 116r) that drives the drive shaft 14. The front drive unit 116f includes a differential mechanism 124 and other components. The front drive unit 116f is the first drive unit of the present invention. The differential mechanism 124 and the front drive shaft 14f are connected via a front power transmission mechanism 20 and other components, as in the first embodiment described above. The rear drive unit 116r is the second drive unit of the present invention.

[0086] The differential mechanism 124 is a double-pinion planetary gear device of the present invention that includes a sun gear S, pinions Pa and Pb, a carrier C, and a ring gear R. A second electric motor MG2 is connected to the sun gear S. An engine 18 and a first electric motor MG1 are connected to the ring gear R. A front drive shaft 14f is connected to the carrier C via a counter gear pair 26, a final gear pair 30, etc.

[0087] The first electric motor MG1 is connected to the input shaft 22, which is connected to the ring gear R, via a power transmission member 40. In this embodiment, the second intermediate gear 40b is fixed to the input shaft 22 so as not to rotate relative to it. One end of the brake BR is connected to the input shaft 22, and the other end is connected to a non-rotating member (not shown) such as a case.

[0088] In the front drive unit 116f, the second electric motor MG2, the differential mechanism 124, and the counter drive gear 34 are arranged on the first axis CS1 in the order of the counter drive gear 34, the differential mechanism 124, and the second electric motor MG2, starting from the engine 18. The final drive gear 38 is arranged closer to the second electric motor MG2 than the counter driven gear 36 in the direction of the counter driven shaft 28.

[0089] FIG. 11 is a nomographic diagram illustrating the configuration of the vehicle drive device 110. In FIG. 11, the differential mechanism 124 of the front drive device 110f has three rotating elements: a first rotating element RE1, a second rotating element RE2, and a third rotating element RE3. Each of the rotating elements RE1-RE3 of the differential mechanism 124 is coupled to an actuator. Expressed using the nomographic diagram, the first rotating element RE1 is a ring gear R. The engine 18 and a first electric motor MG1 are coupled to the first rotating element RE1. The second rotating element RE2 is a sun gear S. The second rotating element RE2 is coupled to a second electric motor MG2. The third rotating element RE3 is a carrier C. The front drive shaft 14f, i.e., the front wheels 12f, are coupled to the third rotating element RE3 via a counter gear pair 26, a final gear pair 30, and the like. The brake BR is a brake mechanism of the present invention that stops rotation of the first rotating element RE1 when engaged. The rear drive unit 110r is the same as the rear drive unit 10r of the first embodiment described above, and therefore a description thereof will be omitted.

[0090] Similar to the vehicle drive device 10 of the first embodiment described above, the vehicle drive device 110 is capable of switching the drive mode between multiple modes by controlling the engine 18, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3.

[0091] In the differential mechanism 124, the rotational speed of the third rotating element RE3, which is the output element, is set to the speed-increasing side, i.e., the overdrive (O / D) side, relative to the engine rotational speed Ne at the mechanical point. That is, in the differential mechanism 124, the mechanical point is set by the speed-increasing ratio. Therefore, in the vehicle drive system 110, Mode 3 is an O / D input split mode, and Mode 4 is an O / D output split mode.

[0092] As described above, according to this embodiment, similar to the first embodiment, in the vehicle drive system 110 that can realize a variety of modes, the axial dimension of the front drive unit 116f can be reduced.

[0093] Furthermore, according to this embodiment, the differential mechanism 124 is a double-pinion planetary gear device, with the first rotating element RE1 being the ring gear R, the second rotating element RE2 being the sun gear S, and the third rotating element RE3 being the carrier C. This makes it possible to shorten the axial dimension of the front drive unit 116f when setting the mechanical point in the differential mechanism 124 using the speed-up ratio. [Example]

[0094] FIG. 12 is a diagram illustrating the schematic configuration of a vehicle 200 equipped with a vehicle drive system 210 (including a front drive system 210f and a rear drive system 210r) to which the present invention is applied. In FIG. 12, the vehicle drive system 210 includes a drive shaft 14 that drives the drive wheels 12 and a drive unit 216 (including a front drive unit 216f and a rear drive unit 216r) that drives the drive shaft 14. The front drive unit 216f includes a differential mechanism 224 and other components. The front drive unit 216f is the first drive unit of the present invention. The differential mechanism 224 and the front drive shaft 14f are connected via a front power transmission mechanism 20 and other components, as in the first embodiment described above. The rear drive unit 216r is the second drive unit of the present invention.

[0095] The differential mechanism 224 is a single-pinion planetary gear device of the present invention that has a sun gear S, a pinion P, a carrier C, and a ring gear R. A second electric motor MG2 is connected to the sun gear S. The engine 18 and a first electric motor MG1 are connected to the ring gear R. A front drive shaft 14f is connected to the carrier C via a counter gear pair 26, a final gear pair 30, etc.

[0096] The first electric motor MG1 is connected to the input shaft 22, which is connected to the ring gear R, via a power transmission member 40. In this embodiment, the second intermediate gear 40b is fixed to the input shaft 22 so as not to rotate relative to it. One end of the brake BR is connected to the input shaft 22, and the other end is connected to a non-rotating member (not shown) such as a case.

[0097] In the front drive unit 216f, the second electric motor MG2, the differential mechanism 224, and the counter drive gear 34 are arranged on the first axis CS1 in the order of the counter drive gear 34, the differential mechanism 224, and the second electric motor MG2, starting from the engine 18. The final drive gear 38 is arranged closer to the second electric motor MG2 than the counter driven gear 36 in the direction of the counter driven shaft 28.

[0098] FIG. 13 is a nomographic diagram illustrating the configuration of the vehicle drive device 210. In FIG. 13, the differential mechanism 224 of the front drive device 210f has three rotating elements: a first rotating element RE1, a second rotating element RE2, and a third rotating element RE3. Each of the rotating elements RE1-RE3 of the differential mechanism 224 is coupled to an actuator. Expressed using the nomographic diagram, the first rotating element RE1 is a ring gear R. The engine 18 and the first electric motor MG1 are coupled to the first rotating element RE1. The second rotating element RE2 is a sun gear S. The second rotating element RE2 is coupled to the second electric motor MG2. The third rotating element RE3 is a carrier C. The front drive shaft 14f, i.e., the front wheels 12f, are coupled to the third rotating element RE3 via a counter gear pair 26, a final gear pair 30, and the like. The brake BR is a brake mechanism of the present invention that stops rotation of the first rotating element RE1 when engaged. The rear drive unit 210r is the same as the rear drive unit 10r of the first embodiment described above, and therefore a description thereof will be omitted.

[0099] Similar to the vehicle drive device 10 of the first embodiment described above, the vehicle drive device 210 is capable of switching the drive mode between multiple modes by controlling the engine 18, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3.

[0100] In differential mechanism 224, the rotational speed of third rotating element RE3, which is the output element, is on the deceleration side, i.e., underdrive (U / D) side, relative to engine rotational speed Ne at the mechanical point. That is, in differential mechanism 224, the mechanical point is set by the reduction ratio. Therefore, in vehicle drive system 210, Mode 3 is U / D input split mode, and Mode 4 is U / D output split mode.

[0101] As described above, according to this embodiment, similar to the first embodiment described above, in the vehicle drive system 210 that can realize a variety of modes, the axial dimension of the front drive unit 216f can be reduced.

[0102] Furthermore, according to this embodiment, the differential mechanism 224 is a single-pinion planetary gear device, with the first rotating element RE1 being the ring gear R, the second rotating element RE2 being the sun gear S, and the third rotating element RE3 being the carrier C. This makes it possible to shorten the axial dimension of the front drive unit 216f when setting the mechanical point in the differential mechanism 224 using the reduction ratio. [Example]

[0103] FIG. 14 is a diagram illustrating the schematic configuration of a vehicle 300 equipped with a vehicle drive system 310 (including a front drive system 310f and a rear drive system 310r) to which the present invention is applied. In FIG. 14, the vehicle drive system 310 includes a drive shaft 14 that drives the drive wheels 12 and a drive unit 316 (including a front drive unit 316f and a rear drive unit 316r) that drives the drive shaft 14. The front drive unit 316f includes a differential mechanism 324 and other components. The front drive unit 316f is the first drive unit of the present invention. The differential mechanism 324 and the front drive shaft 14f are connected via a front power transmission mechanism 20 and other components, as in the first embodiment described above. The rear drive unit 316r is the second drive unit of the present invention.

[0104] The differential mechanism 324 is a single-pinion planetary gear device of the present invention that has a sun gear S, a pinion P, a carrier C, and a ring gear R. A second electric motor MG2 is connected to the sun gear S. The engine 18 and a first electric motor MG1 are connected to the carrier C. A front drive shaft 14f is connected to the ring gear R via a counter gear pair 26, a final gear pair 30, etc.

[0105] As in the first embodiment, the first electric motor MG1 is connected to the carrier C via a power transmission member 40. One end of the brake BR is connected to the input shaft 22, and the other end is connected to a non-rotating member (not shown) such as a case.

[0106] In the front drive unit 316f, the second electric motor MG2, the differential mechanism 324, and the counter drive gear 34 are arranged on the first axis CS1 in the order of the counter drive gear 34, the differential mechanism 324, and the second electric motor MG2, starting from the engine 18. The final drive gear 38 is arranged closer to the second electric motor MG2 than the counter driven gear 36 in the direction of the counter driven shaft 28.

[0107] FIG. 15 is a nomographic diagram illustrating the configuration of a vehicle drive device 310. In FIG. 15, a differential mechanism 324 of a front drive device 310f has three rotating elements: a first rotating element RE1, a second rotating element RE2, and a third rotating element RE3. Each of the rotating elements RE1-RE3 of the differential mechanism 324 is coupled to an actuator. Expressed using the nomographic diagram, the first rotating element RE1 is the carrier C. The engine 18 and the first electric motor MG1 are coupled to the first rotating element RE1. The second rotating element RE2 is the sun gear S. The second rotating element RE2 is coupled to the second electric motor MG2. The third rotating element RE3 is the ring gear R. The front drive shaft 14f, i.e., the front wheels 12f, are coupled to the third rotating element RE3 via a counter gear pair 26, a final gear pair 30, and the like. The brake BR is a brake mechanism of the present invention that stops rotation of the first rotating element RE1 when engaged. The rear drive unit 310r is the same as the rear drive unit 10r of the first embodiment described above, and therefore a description thereof will be omitted.

[0108] Similar to the vehicle drive device 10 of the first embodiment described above, the vehicle drive device 310 is capable of switching the drive mode between multiple modes by controlling the engine 18, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3.

[0109] In the differential mechanism 324, the rotational speed of the third rotating element RE3, which is the output element, is set to the speed-increasing side, or overdrive (O / D) side, relative to the engine rotational speed Ne at a mechanical point. That is, in the differential mechanism 324, the mechanical point is set by a speed-increasing ratio. Therefore, in the vehicle drive device 310, Mode 3 is an O / D input split mode, and Mode 4 is an O / D output split mode.

[0110] As described above, according to this embodiment, similar to the first embodiment, in the vehicle drive system 310 that can realize a variety of modes, the axial dimension of the front drive unit 316f can be reduced.

[0111] Furthermore, according to this embodiment, the differential mechanism 324 is a single-pinion planetary gear device, with the first rotating element RE1 being the carrier C, the second rotating element RE2 being the sun gear S, and the third rotating element RE3 being the ring gear R. This makes it possible to shorten the axial dimension of the front drive unit 316f when setting the mechanical point in the differential mechanism 324 using the speed-up ratio. Furthermore, when connecting the front drive shaft 14f to the third rotating element RE3 via the counter gear pair 26, the final gear pair 30, etc., the configuration can be simplified, allowing the size of the front drive unit 316f to be reduced. [Example]

[0112] FIG. 16 is a nomographic diagram illustrating the configuration of a vehicle drive device 410 (including a front drive device 410f and a rear drive device 410r). In FIG. 16, the vehicle drive device 410 differs from the configuration of the vehicle drive device 10 in the first embodiment in that the brake BR provided in the vehicle drive device 10 is replaced with a one-way clutch OWC. The brake mechanism of the present invention, which stops the rotation of the first rotating element RE1 by being engaged, may use a one-way clutch OWC instead of the brake BR. Similarly, the vehicle drive devices 110, 210, and 310 in the second to fourth embodiments may also use a one-way clutch OWC instead of the brake BR.

[0113] The one-way clutch OWC has two rotating elements, for example, inner and outer rings, that are rotatable relative to one another. One of these rotating elements is connected to the first rotating element RE1, and the other is connected to a non-rotating member (not shown), such as a case. The one-way clutch OWC is idling in the forward rotation direction, which is the rotation direction when the engine 18 is running, while automatically engaging in the reverse rotation direction. In other words, the one-way clutch OWC is an engagement device that allows the first rotating element RE1 to rotate in the forward rotation direction, which is the rotation direction when the engine 18 is running, and prevents the first rotating element RE1 from rotating in the reverse rotation direction. The one-way clutch OWC is automatically engaged by the interaction between the inner ring and the outer ring. Therefore, the one-way clutch OWC does not require a control command signal, such as the brake control command signal Sbr, for controlling the brake BR to be engaged or released.

[0114] FIG. 17 is a nomographic diagram illustrating Mode1_MG2_OWC, a BEV mode in which torque is generated by the second electric motor MG2 with the one-way clutch OWC engaged. Mode1_MG2_OWC is one of Modes 1 that allows BEV driving. In FIG. 17, Mode1_MG2_OWC is included in multiple modes that allow switching of the drive mode. Mode1_MG2_OWC is a mode in which the engine 18 is stopped and torque is generated by the second electric motor MG2 with the one-way clutch OWC engaged, thereby performing BEV driving. In Mode1_MG2_OWC, the rotational speed of the first rotating element RE1 is fixed to zero due to the engagement of the one-way clutch OWC, so BEV driving is enabled by the second electric motor MG2 using power from the battery 64. At this time, BEV driving is enabled with maximum torque of the second electric motor MG2. In Mode1_MG2_OWC, as shown in FIG. 17, it is also possible to increase the drive torque by generating torque in the third electric motor MG3.

[0115] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained. [Example]

[0116] FIG. 18 is a diagram illustrating the setting of the helix angles of the ring gear R of the differential mechanism 24 and the counter drive gear 34 in the configuration of the vehicle drive system 10 in the first embodiment described above. In FIG. 18, the front drive unit 16f further includes a bearing 80 that supports the counter drive gear 34. The bearing 80 supports, for example, the counter drive gear 34 rotatably relative to a front case 90. The front case 90 is a non-rotating member that houses the front drive unit 16f. The sun gear S of the differential mechanism 24, the ring gear R of the differential mechanism 24, and the counter drive gear 34 are each helical gears.

[0117] In the front drive unit 16f, power from the engine 18 and power from the second electric motor MG2 are input to the counter drive gear 34. If a large input load is applied to the bearing 80, this will result in an increase in the size of the bearing 80 and an increase in loss.

[0118] Therefore, in the front drive unit 16f, in order to reduce the input load to the bearing 80, at least a portion of the thrust force generated in the counter drive gear 34 is offset by the thrust force generated in the ring gear R.

[0119] The helix angles of the sun gear S, the ring gear R, and the counter drive gear 34 are set so that the direction of the thrust force generated in the ring gear R by the meshing reaction force is opposite to the direction of the thrust force generated in the counter drive gear 34 by the meshing reaction force. In other words, the helix angles of the sun gear S, the ring gear R, and the counter drive gear 34 are set so that the thrust force generated in the ring gear R and the thrust force generated in the counter drive gear 34 are opposite to each other.

[0120] In Figure 18, the black arrow DTra indicates the direction of the thrust force acting on the ring gear R, which is directed toward the counter drive gear 34. The black arrow DTda indicates the direction of the thrust force acting on the counter drive gear 34, which is opposite to the direction of the black arrow DTra. In the front drive unit 16f, the torsion angles of the sun gear S, ring gear R, and counter drive gear 34 are set so that thrust forces in the directions indicated by the black arrows DTra and DTda are generated. Alternatively, the dashed arrow DTrb indicates the direction of the thrust force acting on the ring gear R, which is opposite to the direction toward the counter drive gear 34. The dashed arrow DTdb indicates the direction of the thrust force acting on the counter drive gear 34, which is opposite to the direction indicated by the dashed arrow DTrb. In the front drive unit 16f, the torsion angles of the sun gear S, ring gear R, and counter drive gear 34 are set so that thrust forces are generated in the directions indicated by the dashed arrows DTrb and DTdb.

[0121] As described above, according to this embodiment, the helix angles of the sun gear S, ring gear R, and counter drive gear 34 are set so that the direction of the thrust force generated on the ring gear R by the meshing reaction force is opposite to the direction of the thrust force generated on the counter drive gear 34 by the meshing reaction force. This causes at least a portion of the thrust force generated on the ring gear R and the thrust force generated on the counter drive gear 34 to cancel each other out, thereby reducing the input load to the bearing 80. Therefore, in addition to the same effects as those of the first embodiment, the bearing 80 can be made smaller and its loss can be reduced. [Example]

[0122] In the front drive unit 16f of Figure 18, when the direction of the thrust force generated in the sun gear S by the meshing reaction force is opposite to the direction toward the bearing 80, the input load to the bearing 80 can be reduced more than when the thrust force is directed toward the bearing 80. The differential mechanism 24 is a double-pinion planetary gear device. Therefore, when the direction of the thrust force generated in the ring gear R is directed toward the counter drive gear 34, the direction of the thrust force generated in the sun gear S by the meshing reaction force is opposite to the direction toward the bearing 80.

[0123] The torsion angle of the ring gear R is set to an angle that causes the direction of the thrust force generated in the ring gear R by the meshing reaction force to be directed from the ring gear R to the counter drive gear 34. In other words, the torsion angles of the sun gear S, ring gear R, and counter drive gear 34 are each set so that the direction of the thrust force generated in the ring gear R is directed from the ring gear R to the counter drive gear 34.

[0124] 18, the black arrow DTsa indicates the direction of the thrust force acting on the sun gear S, which is opposite to the direction toward the bearing 80. In the front drive unit 16f, the torsion angles of the sun gear S, ring gear R, and counter drive gear 34 are set so that thrust forces are generated in the directions indicated by the black arrows DTra, DTda, and DTsa, respectively.

[0125] As described above, according to this embodiment, the torsion angle of the ring gear R is set to an angle that causes the direction of the thrust force generated in the ring gear R by the meshing reaction force to be directed from the ring gear R toward the counter drive gear 34. As a result, the direction of the thrust force generated in the sun gear S by the meshing reaction force is opposite to the direction toward the bearing 80, and the input load to the bearing 80 can be suitably reduced. [Example]

[0126] FIG. 19 is a diagram illustrating the setting of the torsion angles of the ring gear R of the differential mechanism 324 and the counter drive gear 34 in the configuration of the vehicle drive device 310 in the aforementioned fourth embodiment. In FIG. 19, the front drive unit 316f further includes a bearing 330 that supports the counter drive gear 34. The bearing 330 supports, for example, the counter drive gear 34 rotatably with respect to the front case 340. The front case 340 is a non-rotating member that houses the front drive unit 316f. The sun gear S of the differential mechanism 324, the ring gear R of the differential mechanism 324, and the counter drive gear 34 are each helical gears.

[0127] In the front drive unit 316f, power from the engine 18 and power from the second electric motor MG2 are input to the counter drive gear 34. If a large input load is applied to the bearing 330, this will result in an increase in the size of the bearing 330 and an increase in loss.

[0128] Therefore, in the front drive unit 316f, in order to reduce the input load to the bearing 330, at least a part of the thrust force generated in the counter drive gear 34 is offset by the thrust force generated in the ring gear R.

[0129] The helix angles of the sun gear S, the ring gear R, and the counter drive gear 34 are set so that the direction of the thrust force generated in the ring gear R by the meshing reaction force is opposite to the direction of the thrust force generated in the counter drive gear 34 by the meshing reaction force. In other words, the helix angles of the sun gear S, the ring gear R, and the counter drive gear 34 are set so that the thrust force generated in the ring gear R and the thrust force generated in the counter drive gear 34 are opposite to each other.

[0130] In Figure 19, the black arrow DTrc indicates the direction of the thrust force acting on the ring gear R, which is directed toward the counter drive gear 34. The black arrow DTdc indicates the direction of the thrust force acting on the counter drive gear 34, which is opposite to the direction of the black arrow DTrc. In the front drive unit 316f, the torsion angles of the sun gear S, ring gear R, and counter drive gear 34 are set so that thrust forces in the directions indicated by the black arrows DTrc and DTdc are generated. Alternatively, the dashed arrow DTrd indicates the direction of the thrust force acting on the ring gear R, which is opposite to the direction toward the counter drive gear 34. The dashed arrow DTdd indicates the direction of the thrust force acting on the counter drive gear 34, which is opposite to the direction indicated by the dashed arrow DTrd. In the front drive unit 316f, the torsion angles of the sun gear S, ring gear R, and counter drive gear 34 are set so that thrust forces are generated in the directions indicated by the dashed arrows DTrd and DTdd.

[0131] As described above, according to this embodiment, the helix angles of the sun gear S, ring gear R, and counter drive gear 34 are set so that the direction of the thrust force generated on the ring gear R by the meshing reaction force is opposite to the direction of the thrust force generated on the counter drive gear 34 by the meshing reaction force. This causes at least a portion of the thrust force generated on the ring gear R and the thrust force generated on the counter drive gear 34 to cancel each other out, thereby reducing the input load to the bearing 330. Therefore, in addition to the same effects as those of the fourth embodiment, the bearing 330 can be made smaller and its loss can be reduced.

[0132] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0133] For example, in the above-described first to eighth embodiments, the rear drive units 10r, 110r, 210r, 310r, and 410r may not be provided. Even in this case, the present invention can be applied in which the first electric motor MG1 is disposed on the second axis CS2 and the counter drive gear 34 is disposed closer to the engine 18 than the differential mechanisms 24, 124, 224, and 324. Furthermore, various drive modes such as "Mode1_MG2," "Mode1_MG2_BRon," "Mode4," and "Mode1_MG2_OWC" can be realized.

[0134] Furthermore, in the differential mechanism 24 of the above-described first, fifth, sixth, and seventh embodiments, the first rotating element RE1 may be one of the carrier C and the sun gear S, and the second rotating element RE2 may be the other of the carrier C and the sun gear S. When the first rotating element RE1 is the sun gear S and the second rotating element RE2 is the carrier C, the engine 18 and the first electric motor MG1 are connected to the sun gear S, and the second electric motor MG2 is connected to the carrier C.

[0135] In the differential mechanism 124 of the second embodiment described above, the second rotating element RE2 may be one of the sun gear S and the carrier C, and the third rotating element RE3 may be the other of the sun gear S and the carrier C. When the second rotating element RE2 is the carrier C and the third rotating element RE3 is the sun gear S, the second electric motor MG2 is connected to the carrier C, and the front drive shaft 14f is connected to the sun gear S.

[0136] In the differential mechanism 224 of the third embodiment described above, the first rotating element RE1 may be one of the ring gear R and the sun gear S, and the second rotating element RE2 may be the other of the ring gear R and the sun gear S. When the first rotating element RE1 is the sun gear S and the second rotating element RE2 is the ring gear R, the engine 18 and the first electric motor MG1 are connected to the sun gear S, and the second electric motor MG2 is connected to the ring gear R.

[0137] In the differential mechanism 324 of the aforementioned fourth embodiment, the second rotating element RE2 may be one of the sun gear S and the ring gear R, and the third rotating element RE3 may be the other of the sun gear S and the ring gear R. When the second rotating element RE2 is the ring gear R and the third rotating element RE3 is the sun gear S, the second electric motor MG2 is connected to the ring gear R, and the front drive shaft 14f is connected to the sun gear S. In the differential mechanism 324 of the aforementioned eighth embodiment, the second rotating element RE2 is limited to the sun gear S, and the third rotating element RE3 is limited to the ring gear R.

[0138] Here, as shown in the above-mentioned Examples 1-8, the second rotating element RE2 is a rotating element that is arranged at either end of a nomographic diagram in which the three rotating elements of the differential mechanism are arranged in a straight line.

[0139] In the above-described Examples 1-8, the power transmission member 40 may be, for example, a chain and sprocket, or a gear pair. For example, when the power transmission member 40 is a gear pair, the first intermediate gear 40a and the second intermediate gear 40b are connected via counter gears that mesh with each other.

[0140] In addition, in the above-described Examples 1-4 and 6-8, the brake BR does not necessarily have to be provided. In this case, Mode1_MG2_BRon of Mode 1 is not executed. As described above, in Mode1_MG3, BEV driving is possible even if the brake BR is not engaged, so Mode1_MG3 can be executed even if the brake BR is not provided.

[0141] In the fifth embodiment, the one-way clutch OWC does not necessarily have to be provided. In this case, Mode1_MG2_OWC is not executed. When the one-way clutch OWC is not provided, Mode1_MG2, which performs BEV driving by generating torque in the first electric motor MG1, is possible. Furthermore, Mode1_MG3 can be executed even if the one-way clutch OWC is not provided.

[0142] In addition, in the above-described Examples 1-8, one of the front wheels 12f and the rear wheels 12r to which the power of the engine 18 or the second electric motor MG2 is transmitted may be the rear wheels 12r, and the other of the front wheels 12f and the rear wheels 12r to which the power of the third electric motor MG3 is transmitted may be the front wheels 12f. In other words, the first drive shaft may be the rear drive shaft 14r, and the second drive shaft may be the front drive shaft 14f.

[0143] Furthermore, in the above-mentioned Examples 1-8, since it is expected that BEV driving using Mode1_MG3 will be frequently used in a PHEV, a drive unit equipped with the third electric motor MG3 is used as the main engine, but in an HEV, a drive unit equipped with the engine 18 or the second electric motor MG2 may be used as the main engine.

[0144] In addition, in the above-described Examples 1-8, the front power transmission mechanism 20 may further include a clutch mechanism that, when disengaged, interrupts power transmission between the third rotating element RE3 and the front drive shaft 14f. The clutch mechanism is controlled to a disengaged state when the vehicle is traveling in a BEV mode, such as Mode1_MG3, in which torque is generated by the third electric motor MG3. This prevents power loss due to drag of components upstream of the front drive shaft 14f, such as the second electric motor MG2, during BEV traveling using the third electric motor MG3 as a power source.

[0145] In addition, in the above-described Examples 1-8, the rear power transmission mechanism 50 may further include a clutch mechanism that is disengaged to interrupt power transmission between the third electric motor MG3 and the rear drive shaft 14r. The clutch mechanism is controlled to the disengaged state when the vehicle is traveling in a BEV mode that causes the second electric motor MG2 to generate torque, such as Mode1_MG2 or Mode1_MG2_BRon. This prevents power loss due to drag of the third electric motor MG3 during BEV traveling using the second electric motor MG2 as a power source.

[0146] In addition, in FIG. 9 of the first embodiment described above, the forward and backward directions may be reversed.

[0147] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0148] 8: Vehicle 10: Vehicle drive unit 12f: Front wheels 12r: Rear wheels 14f: Front drive shaft (first drive shaft) 14r: Rear drive shaft (second drive shaft) 16f: Front drive unit (first drive unit) 16r: Rear drive unit (second drive unit) 18: Engine 24: Differential mechanism (double pinion type planetary gear device) S: Sun gear (second rotating element) C: Carrier (first rotating element) R: Ring gear (third rotating element) 26: Counter gear pair (first gear pair) 28: Counter driven shaft 30: Final gear pair (second gear pair) 32: Front differential gear (differential gear) 32r: Final driven gear (input rotating member) 34: Counter drive gear 36: Counter driven gear 38: Final drive gear 40: Power transmission member 80: Bearing 100: Vehicle 110: Vehicle drive device 116f: Front drive unit (first drive unit) 116r: Rear drive unit (second drive unit) 124: Differential mechanism (double pinion type planetary gear device) S: Sun gear (second rotating element) C: Carrier (third rotating element) R: Ring gear (first rotating element) 200: Vehicle 210: Vehicle drive device 216f: Front drive unit (first drive unit) 216r: Rear drive unit (second drive unit) 224: Differential mechanism (single pinion type planetary gear device) S: Sun gear (second rotating element) C: Carrier (third rotating element) R: Ring gear (first rotating element) 300: Vehicle 310: Vehicle drive device 316f: Front drive unit (first drive unit) 316r: Rear drive unit (second drive unit) 324: Differential mechanism (single pinion type planetary gear device) S: Sun gear (second rotating element) C: Carrier (first rotating element) R: Ring gear (third rotating element) 330: Bearing 410: Vehicle drive unit BR: Brake (brake mechanism) CS1: First shaft center CS2: Second shaft center MG1: First electric motor MG2: Second electric motor MG3: Third electric motor OWC: One-way clutch (brake mechanism) RE1: First rotating element RE2: Second rotating element RE3: Third rotating element

Claims

1. A vehicle drive device including an engine, a first drive unit including a planetary gear device having a first electric motor, a second electric motor, and three rotation elements, i.e., a first rotation element, a second rotation element, and a third rotation element, and a first drive shaft that drives one of front wheels and rear wheels, the first drive unit further includes a first gear pair having a counter drive gear and a counter driven gear meshing with the counter drive gear, a counter driven shaft arranged parallel to the first drive shaft and on which the counter driven gear is non-rotatable relative to the first drive shaft, and a second gear pair having a final drive gear arranged alongside the counter driven gear on the counter driven shaft and non-rotatable relative to the counter driven shaft, and a final driven gear meshing with the final drive gear, the first drive unit is configured such that the engine and the first electric motor are connected to the first rotating element, the second electric motor is connected to the second rotating element, and the first drive shaft is connected to the third rotating element via the first gear pair and the second gear pair, the second electric motor, the planetary gear device, and the counter drive gear are arranged in the order of the counter drive gear, the planetary gear device, and the second electric motor from the engine side on a first axis that is a rotation axis of the planetary gear device and that is parallel to the counter driven shaft, A vehicle drive device characterized in that the first electric motor is arranged on a second axis, which is a rotational axis parallel to the first axis, and is connected to the first rotating element via a power transmission member.

2. the planetary gear device is a double-pinion planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is one of the carrier and the sun gear, the second rotating element is the other of the carrier and the sun gear, 2. The vehicle drive device according to claim 1, wherein the third rotating element is the ring gear.

3. the first drive unit further includes a bearing that supports the counter drive gear; the sun gear, the ring gear, and the counter drive gear are each helical gears, 3. The vehicle drive device according to claim 2, wherein the twist angles of the sun gear, the ring gear, and the counter drive gear are set such that the direction of the thrust force generated in the ring gear by the meshing reaction force and the direction of the thrust force generated in the counter drive gear by the meshing reaction force are opposite to each other.

4. 4. The vehicle drive device according to claim 3, wherein the torsion angle of the ring gear is an angle that causes a thrust force generated in the ring gear by a meshing reaction force to be directed from the ring gear toward the counter drive gear.

5. the planetary gear device is a double-pinion planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is the ring gear, the second rotating element is one of the sun gear and the carrier, 2. The vehicle drive device according to claim 1, wherein the third rotating element is the other of the sun gear and the carrier.

6. the planetary gear device is a single-pinion planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is one of the ring gear and the sun gear, the second rotating element is the other of the ring gear and the sun gear, 2. The vehicle drive device according to claim 1, wherein the third rotating element is the carrier.

7. the planetary gear device is a single-pinion planetary gear device having a sun gear, a carrier, and a ring gear, the first rotating element is the carrier, the second rotating element is one of the sun gear and the ring gear, 2. The vehicle drive device according to claim 1, wherein the third rotating element is the other of the sun gear and the ring gear.

8. the second rotating element is the sun gear, the third rotating element is the ring gear, the first drive unit further includes a bearing that supports the counter drive gear; the sun gear, the ring gear, and the counter drive gear are each helical gears, 8. The vehicle drive device according to claim 7, wherein the twist angles of the sun gear, the ring gear, and the counter drive gear are set such that the direction of the thrust force generated in the ring gear by the meshing reaction force and the direction of the thrust force generated in the counter drive gear by the meshing reaction force are opposite to each other.

9. 2. The vehicle drive device according to claim 1, wherein the counter driven shaft is disposed in a position vertically below a position horizontal to the first axis when the device is mounted on the vehicle.

10. 2. The vehicle drive device according to claim 1, wherein the final drive gear is positioned closer to the second electric motor than the counter driven gear in the axial direction of the counter driven gear.

11. 2. The vehicle drive device according to claim 1, wherein the final driven gear is an input rotating member of a differential gear that is arranged on the rotational axis of the first drive shaft and is connected to the first drive shaft.

12. 2. The vehicle drive device according to claim 1, wherein the first drive unit further includes a brake mechanism that stops rotation of the first rotating element by being brought into an engaged state.

13. 13. The vehicle drive device according to claim 1, further comprising: a second drive shaft that drives the other of the front wheels and the rear wheels; and a second drive unit including a third electric motor connected to the second drive shaft.

Images