Vehicle drive device

Abstract

Provided is a vehicle drive device capable of making a vehicle body less susceptible to vibration when the vehicle is driven with the engine running.　In a differential mechanism, the engine and a first electric motor are coupled to a first rotating element, a second electric motor is coupled to a second rotating element, and a first drive shaft for driving either front wheels or rear wheels is coupled to a third rotating element. Further, a third electric motor is coupled to a second drive shaft for driving the other of the front wheels and the rear wheels. As a result, a plurality of modes can be realized as driving modes. For example, when the vehicle is driven with the engine running, what is known as series drive can be performed by operating the first electric motor that is coupled to the same rotating element as the engine as an electricity generator, and driving the second drive shaft by operating the third electric motor as a prime mover using the generated electric power. In the mode in which series drive is performed, it is possible to prevent torque vibration of the engine from being transmitted to the first drive shaft.

Description

Vehicle drive unit

[0001] The present invention relates to a vehicle drive system including an engine, three electric motors, a differential mechanism, and drive shafts for driving front and rear wheels, respectively.

[0002] A well-known vehicle drive system includes an engine, a first electric motor, a second electric motor, a third electric motor, a differential mechanism, a first drive shaft that drives one of the front wheels and the rear wheels, and a second drive shaft that drives the other of the front wheels and the rear wheels. For example, a vehicle drive system described in Patent Document 1 (Patent Document 1) is such a system. Patent Document 1 discloses that the differential mechanism has four rotating elements: a first rotating element, a second rotating element, a third rotating element, and a fourth rotating element. Patent Document 1 also discloses that the engine is connected to the first rotating element, the first electric motor is connected to the second rotating element, the second electric motor is connected to the third rotating element, and the first drive shaft is connected to the fourth rotating element. Patent Document 1 also discloses that the third electric motor is connected to the second drive shaft.

[0003] U.S. Patent No. 8,512,189

[0004] The vehicle drive system of Patent Document 1 realizes a compound split mode in which, while the engine is running, one of the first and second electric motors is operated as a generator and the other is operated as a prime mover to drive the first drive shaft. The vehicle drive system of Patent Document 1 also realizes an input split mode in which, while the engine is running, one of the first and second electric motors is operated as a generator and the third electric motor is operated as a prime mover to drive the second drive shaft. However, when the vehicle is running with the engine running, the first or second electric motor generates a reaction torque against the engine torque, and engine torque vibration is transmitted to the first drive shaft, which may cause vibration of the vehicle body.

[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 vibration of the vehicle body when the vehicle is driven with the engine running.

[0006] The gist of the first invention is (a) a vehicle drive device including an engine, a first electric motor, a second electric motor, a third electric motor, a differential mechanism, a first drive shaft that drives one of the front wheels and the rear wheels, and a second drive shaft that drives the other of the front wheels and the rear wheels, (b) the differential mechanism has three rotating elements: a first rotating element, a second rotating element, and a third rotating element, (c) 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, and (d) the third electric motor is connected to the second drive shaft.

[0007] Furthermore, a second invention is a vehicle drive device described in the first invention, wherein the differential mechanism 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.

[0008] Furthermore, a third invention is a vehicle drive device described in the first invention, wherein the differential mechanism 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, and the third rotating element is the other of the sun gear and the ring gear.

[0009] Furthermore, a fourth invention is a vehicle drive device described in the first invention, wherein the differential mechanism 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, and the third rotating element is the ring gear.

[0010] Furthermore, a fifth invention is a vehicle drive device described in the first invention, wherein the differential mechanism 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, and the third rotating element is the other of the sun gear and the carrier.

[0011] Furthermore, a sixth invention is a vehicle drive device described in any one of the second to fifth inventions, in which the first electric motor is arranged on a rotational axis different from the rotational axis of the planetary gear device, and the first electric motor is connected to the first rotating element via a power transmission member.

[0012] Furthermore, a seventh invention is a vehicle drive device described in any one of the first to fifth inventions, further comprising a brake mechanism that stops the rotation of the first rotating element by being engaged.

[0013] Furthermore, the eighth invention is a vehicle drive device described in any one of the first to fifth inventions, further comprising a clutch mechanism that, when released, cuts off power transmission between the third rotating element and the first drive shaft.

[0014] Furthermore, a ninth invention is that the vehicle drive device described in the eighth invention further includes a parking mechanism that switches between a parking lock state in which a rotating member that rotates together with the second drive shaft is mechanically fixed so as not to rotate, and a non-parking lock state in which the rotating member is rotatable.

[0015] Furthermore, a tenth invention is a vehicle drive device described in any one of the first to fifth inventions, further comprising a clutch mechanism that, when released, cuts off power transmission between the third electric motor and the second drive shaft.

[0016] In addition, an eleventh invention is that the vehicle drive device described in the tenth invention further includes a parking mechanism that switches between a parking lock state in which a rotating member that rotates together with the first drive shaft is mechanically fixed so that it cannot rotate, and a non-parking lock state in which the rotating member is rotatable.

[0017] Furthermore, a twelfth invention is a vehicle drive device described in any one of the first to fifth inventions, further comprising a first clutch mechanism that, when released, cuts off power transmission between the third rotating element and the first drive shaft, and a second clutch mechanism that, when released, cuts off power transmission between the third electric motor and the second drive shaft.

[0018] According to the first aspect of the present invention, an engine and a first electric motor are coupled to a first rotating element of a differential mechanism, a second electric motor is coupled to a second rotating element of the differential mechanism, and a first drive shaft that drives one of the front and rear wheels is coupled to a third rotating element of the differential mechanism. Furthermore, a third electric motor is coupled to a second drive shaft that drives the other of the front and rear wheels. This allows for multiple drive modes by controlling the engine and simultaneously transmitting and receiving electric power from the first, second, and third electric motors. For example, when running a vehicle with the engine running, the first electric motor, which is coupled to the same rotating element as the engine, is operated as a generator, and the third electric motor is operated as a prime mover using the generated electric power to drive the second drive shaft, thereby achieving so-called series running. In the series running mode, torque vibrations of the engine are prevented from being transmitted to the first drive shaft. Therefore, the vehicle body is less likely to vibrate when running a vehicle with the engine running.

[0019] According to the second aspect of the present invention, the differential mechanism is a single-pinion planetary gear set, 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 size of the differential mechanism when the mechanical point at which the rotational speed of the second rotating element, i.e., the rotational speed of the second motor, is set to zero is set using a reduction ratio.

[0020] According to the third aspect of the present invention, the differential mechanism is a single-pinion planetary gear set, 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 makes it possible to reduce the size of the differential mechanism 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 is set using the speed increase ratio.

[0021] According to the fourth aspect of the present invention, the differential mechanism is a double-pinion planetary gear set, the first rotating element is one of a carrier and a 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 makes it possible to reduce the size of the differential mechanism when the mechanical point at which the rotational speed of the second rotating element, i.e., the rotational speed of the second motor, is set to zero is set using a reduction ratio.

[0022] According to the fifth aspect of the present invention, the differential mechanism is a double-pinion planetary gear set, 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 size of the differential mechanism 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 is set using the speed increase ratio.

[0023] According to the sixth aspect of the present invention, the first electric motor is disposed on a rotation axis different from that of the planetary gear device and is connected to the first rotating element via a power transmission member, thereby preventing the size of the first electric motor from increasing in the direction of the rotation axis.

[0024] According to the seventh aspect of the present invention, the vehicle further includes a brake mechanism that stops rotation of the first rotating element, thereby enabling motor running, in which the vehicle runs using the second electric motor as a power source while the engine is stopped, i.e., battery electric vehicle (BEV) running, for example, BEV running at the maximum torque of the second electric motor.

[0025] According to the eighth aspect of the present invention, the vehicle further includes a clutch mechanism that interrupts power transmission between the third rotating element and the first drive shaft. This prevents power loss due to drag of components upstream of the first drive shaft, such as the second electric motor, when the vehicle is driven by the second drive shaft. This is particularly useful when frequently using a mode in which the vehicle runs using the third electric motor as a power source while the second electric motor is stopped.

[0026] According to the ninth aspect of the present invention, in addition to the clutch mechanism that interrupts the power transmission between the third rotating element and the first drive shaft, a parking mechanism that mechanically fixes a rotating member that rotates together with the second drive shaft so that it cannot rotate is further provided. As a result, the clutch mechanism and the parking mechanism are not arranged together on the first drive shaft side, which prevents the vehicle from becoming large in size.

[0027] According to the tenth aspect of the present invention, the vehicle further includes a clutch mechanism that interrupts power transmission between the third electric motor and the second drive shaft, thereby preventing power loss due to drag of the third electric motor when the first drive shaft is driven to run the vehicle.

[0028] According to the eleventh aspect of the present invention, in addition to the clutch mechanism that interrupts the power transmission between the third electric motor and the second drive shaft, a parking mechanism that mechanically fixes a rotating member that rotates together with the first drive shaft so that it cannot rotate is further provided. As a result, the clutch mechanism and the parking mechanism are not arranged together on the second drive shaft side, which prevents the vehicle from becoming large in size.

[0029] According to the twelfth aspect of the present invention, the vehicle further includes a first clutch mechanism that interrupts power transmission between the third rotating element and the first drive shaft, and a second clutch mechanism that interrupts power transmission between the third electric motor and the second drive shaft. This prevents power loss due to drag of a component upstream of the first drive shaft, such as the second electric motor, when the second drive shaft is driven to run the vehicle. Furthermore, it prevents power loss due to drag of the third electric motor when the first drive shaft is driven to run the vehicle.

[0030] 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.

[0023] FIG. 1 is a diagram illustrating the configuration of the vehicle drive device using a nomographic diagram.

[0024] FIG. 1 is a nomographic diagram illustrating a BEV mode in which torque is generated in a first electric motor and a second electric motor.

[0025] FIG. 1 is a nomographic diagram illustrating a BEV mode in which torque is generated in a second electric motor with the brakes engaged.

[0026] FIG. 1 is a nomographic diagram illustrating a BEV mode in which torque is generated in a third electric motor with the brakes engaged.

[0027] FIG. 1 is a nomographic diagram illustrating a first HEV mode (series mode) in which power is exchanged between the first electric motor and the third electric motor by driving the engine to rotate.

[0028] FIG. 1(a) is a nomographic diagram illustrating a case in which torque is generated in the third electric motor by power generation of the first electric motor.

[0029] FIG. 1(b) is a nomographic diagram illustrating a case in which engine braking is applied by consuming power generated by the third electric motor in powering the first electric motor.

[0029] 1A is a nomographic diagram illustrating a case where torque is generated in the third electric motor by electric power generated by the second electric motor. FIG. 1B is a nomographic diagram illustrating a case where torque is generated in the second electric motor by electric power generated by the third electric motor. FIG. 1C is a nomographic diagram illustrating a third HEV mode (output split mode) in which the engine is operated and electric power is exchanged between the first electric motor and the second electric motor. FIG. 1A is a nomographic diagram illustrating a case where torque is generated in the second electric motor by electric power generated by the first electric motor. FIG. 1B is a nomographic diagram illustrating a case where torque is generated in the first electric motor by electric power generated by the second electric motor. FIG. 1C is a nomographic diagram illustrating a schematic configuration of a vehicle equipped with a vehicle drive system to which the present invention is applied, the vehicle being different from the vehicle of FIG. 1. FIG. 1D is a nomographic diagram illustrating a schematic configuration of a vehicle equipped with a vehicle drive system to which the present invention is applied (single pinion O / D type), the vehicle being different from the vehicle of FIG. 1. 12 is a nomographic diagram illustrating the configuration of the vehicle drive device of FIG. 11. FIG. 13 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, and is a diagram illustrating a vehicle different from the vehicle of FIG.FIG. 14 is a nomographic diagram illustrating the configuration of the vehicle drive device of FIG. 13. FIG. 15 is a nomographic diagram illustrating the configuration of a vehicle drive device (double pinion O / D type) to which the present invention is applied, which is a diagram illustrating a vehicle different from the vehicle of FIG. 1. FIG. 16 is a nomographic diagram illustrating the configuration of the vehicle drive device of FIG. 15. FIG. 17 is a nomographic diagram illustrating the configuration of a vehicle drive device different from the vehicle drive device of FIG. 1. FIG. 18 is a nomographic diagram illustrating a BEV mode in which torque is generated in the second electric motor with the one-way clutch engaged. FIG. 19 is a nomographic diagram illustrating the configuration of a vehicle to which the present invention is applied, which is a diagram illustrating a vehicle different from the vehicle of FIG. 1.

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0032] 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 includes 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 unit 10f that drives the front wheels 12f and a rear drive unit 10r that drives the rear wheels 12r. Note that the above "left and right" refer to left and right relative to the forward direction of the vehicle 8.

[0033] The front drive unit 10f includes an engine 20, a first electric motor MG1, a second electric motor MG2, and a front power transmission device 30. The rear drive unit 10r includes a third electric motor MG3 and a rear power transmission device 50. 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.

[0034] The engine 20 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 20. 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.

[0035] 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 controlling the inverter 62 by an electronic control device 70 (described later). The torque of the first electric motor MG1 is a first electric motor torque Tmg1, the torque of the second electric motor MG2 is a second electric motor torque Tmg2, and the torque of the third electric motor MG3 is a third electric motor torque Tmg3. The torque of the electric motor is a power running torque when the electric motor functions as a prime mover, and is a regenerative torque when the electric motor functions as a generator. The battery 64 is an electric storage device that supplies and receives electric power to 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.

[0036] The front power transmission device 30 is provided in a power transmission path between the engine 20, the first electric motor MG1, and the second electric motor MG2, and the front wheels 12f. The front power transmission device 30 includes a differential mechanism 32, a front counter gear 34, a front differential gear 36, and left and right front drive shafts 38. The differential mechanism 32 and the front differential gear 36 are connected via the front counter gear 34. The front drive shaft 38 is connected to the front differential gear 36. The front power transmission device 30 transmits power from the engine 20, the second electric motor MG2, and the like to the front wheels 12f. The front drive shaft 38 is a first drive shaft that drives the front wheels 12f, which are one of the front wheels 12f and the rear wheels 12r.

[0037] The differential mechanism 32 is a single-pinion planetary gear device having a sun gear S, a pinion P, a carrier C that supports the pinion P so that it can rotate and revolve, and a ring gear R that meshes with the sun gear S via the pinion P. A second electric motor MG2 is connected to the sun gear S. The engine 20 and a first electric motor MG1 are connected to the ring gear R. The carrier C meshes with a front counter gear 34. A front drive shaft 38 is connected to the carrier C.

[0038] The engine 20 and the second electric motor MG2 are each disposed on a first axis CS1, which is the rotational axis of the differential mechanism 32. The first electric motor MG1 is disposed on a second axis CS2. The second axis CS2 is a rotational axis different from the first axis CS1 and is parallel to the first axis CS1. Therefore, the front power transmission device 30 further includes a power transmission member 40. The first electric motor MG1 is connected to a ring gear R of the differential mechanism 32 via the power transmission member 40. The power transmission member 40 includes, for example, an intermediate gear 40a fixed to the rotor shaft MG1rs of the first electric motor MG1 so as not to rotate relative to it, and a belt 40b connecting the intermediate gear 40a and the ring gear R. The intermediate gear 40a has a smaller diameter than the ring gear R, and the power transmission member 40 functions, for example, as a reduction mechanism. By arranging the first electric motor MG1 on the second axis CS2, the size of the front drive unit 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.

[0039] The front power transmission device 30 further includes a brake BR. One end of the brake BR is connected to the ring gear R of the differential mechanism 32, 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 power transmission device 30, etc. The brake BR is an engagement device that is operated by, for example, an electric or hydraulic actuator to selectively connect members at both ends. The brake BR functions as a brake mechanism that selectively stops rotation of the ring gear R of the differential mechanism 32. The ring gear R is selectively made non-rotatable or rotatable by the brake BR.

[0040] The rear power transmission device 50 is provided in the power transmission path between the third electric motor MG3 and the rear wheels 12r. The rear power transmission device 50 includes an output gear 52, a rear counter gear 54, a rear differential gear 56, and left and right rear drive shafts 58. 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 meshed 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 drive shafts 58 are connected to the rear differential gear 56. 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. The rear power transmission device 50 transmits power from the third electric motor MG3 to the rear wheels 12r. The rear drive shaft 58 is a second drive shaft that drives the other of the front wheels 12f and the rear wheels 12r, 12r. A third electric motor MG3 is connected to the rear drive shaft 58.

[0041] The rear power transmission device 50 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 power transmission device 50. 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 locked so as to be unable to rotate 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 58. The output gear 52 and the rear drive shaft 58 are selectively locked or unlocked by the parking mechanism PLC.

[0042] 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 executes various controls of the vehicle 8 by, for example, performing signal processing according to a program pre-stored in the ROM. For example, the electronic control unit 70 executes output control of the engine 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3, and executes 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 needed.

[0043] 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 rotation 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.

[0044] 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 20. 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).

[0045] FIG. 2 is a nomographic diagram showing the configuration of the vehicle drive system 10. In FIG. 2, the rear drive unit 10r is a main unit that is used for driving with priority over, for example, the front drive unit 10f. In this case, the front drive unit 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.

[0046] The differential mechanism 32 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. An actuator is connected to each of the rotating elements RE1-RE3 of the differential mechanism 32. The nomographic diagram of FIG. 2 illustrates the three rotating elements of the differential mechanism 32 arranged in a straight line. Expressed using the nomographic diagram, the first rotating element RE1 is a ring gear R. The engine 20 and the first electric motor MG1 are connected to the first rotating element RE1. The second rotating element RE2 is a sun gear S. The second electric motor MG2 is connected to the second rotating element RE2. The third rotating element RE3 is a carrier C. The front drive shaft 38, i.e., the front wheels 12f, are connected to the third rotating element RE3. The brake BR is a brake mechanism that stops rotation of the first rotating element RE1 when engaged.

[0047] 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, the second electric motor MG2, and the 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.

[0048] The electronic control device 70 controls the engine 20, 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.

[0049] 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 rotating elements RE1-RE3 of the differential mechanism 32 in the alignment chart of FIG. 2. In this alignment chart, vertical lines Y1-Y3 are arranged in the order 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 rotating element RE2 connected to the second electric motor MG2. The vertical line Y2 represents the rotational speed of the carrier C, which is the third rotating element RE3 connected to the front wheels 12f (see "FrOUT" in the drawings). The vertical line Y3 represents the rotational speed of the ring gear R, which is the first rotating element RE1 connected to the engine 20 (see "ENG" in the drawings) and the first electric motor MG1. The diagram also shows that the third electric motor MG3 connected to the rear wheel 12r (see "RrOUT" in the diagram) is connected to the front wheel 12f via the ground. The arrows indicate the magnitude and direction of torque converted onto the axis of each rotating element RE1-RE3. The solid arrows indicate torque output from each actuator, and the dashed arrows indicate mechanically transmitted torque.

[0050] 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 enabling 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 20 is stopped and torque is generated in the first electric motor MG1 and the second electric motor MG2 to achieve 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. In this case, the first electric motor torque Tmg1 is controlled, for example, so as to prevent drag of the engine 20, i.e., so that the rotational speed of the first rotating element RE1 becomes zero. In Mode1_MG2, the differential mechanism 32 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.

[0051] FIG. 4 is a nomographic diagram illustrating another BEV mode, Mode1_MG2_BRon, in which the second electric motor MG2 generates torque with the brake BR engaged, which is another mode of Mode 1 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 the engine 20 is stopped and the second electric motor MG2 generates torque with the brake BR engaged, thereby achieving BEV driving. In Mode1_MG2_BRon, the brake BR is engaged and the rotational speed of the first rotating element RE1 is fixed to zero. This enables forward and reverse BEV driving by the second electric motor MG2 using the power of the battery 64 without generating torque in the first electric motor MG1. In this mode, BEV driving is enabled with the maximum torque of the second electric motor MG2. In Mode1_MG2_BRon, the differential mechanism 32 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.

[0052] FIG. 5 is a nomographic diagram illustrating another BEV mode, Mode1_MG3, in which the third electric motor MG3 generates torque with the brake BR engaged, which is another mode of Mode 1 that enables BEV driving. In FIG. 5 , Mode1_MG3 is included in the multiple modes that allow switching of the drive mode. Mode1_MG3 is a mode in which the engine 20 is stopped and the third electric motor MG3 generates torque 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 allows the third electric motor MG3 to drive the vehicle forward and backward using the power of the battery 64 without dragging the engine 20 or the first electric motor MG1.

[0053] In Mode1_MG3, it is also possible to increase the drive torque by causing the second electric motor MG2 to generate torque. Furthermore, in Mode1_MG3, it is also 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 20 is stopped and the third electric motor MG3 is caused to generate torque to perform BEV running.

[0054] Fig. 6 is a nomographic diagram illustrating a first HEV mode, i.e., Mode 2, in which the engine 20 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 a plurality of modes that allow switching of the drive mode. Mode 2 is a mode that allows hybrid driving, i.e., HEV driving, and is a series mode that allows series driving using the engine 20 as a power source.

[0055] In FIG. 6A, Mode 2 includes a mode in which the engine 20 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 electric power generated by 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 input from the engine 20 and the output from the rear wheels 12r. In Mode 2, the power of the engine 20 is converted via the first electric motor MG1, and the electric power generated by 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 20 is not transmitted to the front drive shaft 38, so Mode 2 is advantageous for suppressing NV. "NV" is a general term for noises and vibrations, such as booming sounds, that occur in the vehicle 8, and represents at least one of the noise and vibrations in the vehicle 8. For this reason, Mode 2 is useful for use in low vehicle speed and low load ranges where quietness is required, for example. Furthermore, Mode 2 is less likely to be restricted by booming sounds, for example, when setting the operating point of the engine 20, so the engine 20 can be operated at an operating point that is fuel-efficient.

[0056] In FIG. 6B , 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 20. In Mode 2, the electric power consumed by the powering 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 powering of the first electric motor MG1. The rotation speed of the engine 20 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 20 is operated by injecting fuel, if the engine rotation speed Ne is increased by the first electric motor torque Tmg1 to a value higher than that in the self-sustaining operation state, the torque converted onto the shaft of the first rotating element RE1 is negative torque. The positive torque direction is the direction of torque when the engine 20 is running. The state in which the engine 20 is running is synonymous with the state in which the engine 20 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 20 is not transmitted to the front drive shaft 38, which is advantageous for suppressing NV.

[0057] FIG. 7 is a nomographic diagram illustrating a second HEV mode, i.e., Mode 3, in which the engine 20 is operated and power is exchanged between the second electric motor MG2 and the third electric motor MG3. FIG. 7(a) 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. FIG. 7(b) 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 the 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 20 as a power source. In Mode 3, the differential mechanism 32 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, performing input split mode operation with the engine 20 as the input and the front wheels 12f and rear wheels 12r as the 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 arranged as the output element (RE3).

[0058] The two-dot chain line A in Figure 7(a) indicates a state in which a mechanical point is formed in the differential mechanism 32 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, the rotational speed of the third rotating element RE3, which is the output element, is on the deceleration side, i.e., underdrive (U / D) side, relative to the engine rotational speed Ne. In other words, the mechanical point of the differential mechanism 32 is set by the reduction ratio. In Figure 7, Mode 3 is the U / D input split mode.

[0059] 7A, Mode 3 includes at least a mode in which the engine 20 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 20 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 low vehicle speed / high load range, and is therefore useful for use in, for example, the low vehicle speed / high load range.

[0060] 7(b), 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 20 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. 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 in FIG. 7(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 second electric motor MG2.

[0061] The vehicle drive device 10 is controlled to perform Mode 3 shown in (a) of Fig. 7 during normal driving in which 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 (a) of Fig. 7 is not executed, the vehicle drive device 10 is controlled to perform Mode 3 shown in (b) of Fig. 7.

[0062] FIG. 8 is a nomographic diagram illustrating a third HEV mode, i.e., Mode 4, in which the engine 20 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 the multiple modes that allow switching of the drive mode. Mode 4 is a mode that allows hybrid driving, i.e., HEV driving, and is an output split mode that allows output split driving using the engine 20 as a power source. In Mode 4, the differential mechanism 32 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 in a released state, an electric continuously variable transmission function can be realized, in which the input is the engine 20 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 32 is set by the reduction ratio, Mode 4 in FIG. 8 is a U / D output split mode. Expressed using a nomographic 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 a differential mechanism, the electric motor (MG1) is located at the input element (RE1) to which the engine is connected.

[0063] In (a) of Fig. 8, Mode 4 includes at least a mode in which the engine 20 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 20. In Mode 4, the power of the engine 20 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.

[0064] 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 20 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 20 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.

[0065] The vehicle drive system 10 is controlled to perform Mode 4 shown in (a) of Fig. 8 during normal driving in which 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 system 10 is controlled to perform Mode 4 shown in (b) of Fig. 8.

[0066] As described above, in this embodiment, the engine 20 and the first electric motor MG1 are connected to the first rotating element RE1, the second electric motor MG2 is connected to the second rotating element RE2, and the front drive shaft 38 is connected to the third rotating element RE3. Furthermore, the third electric motor MG3 is connected to the rear drive shaft 58. This allows for multiple drive modes to be realized by controlling the engine 20 and simultaneously transmitting and receiving electric power from the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3. For example, when the vehicle 8 is traveling with the engine 20 running, the first electric motor MG1 can be operated as a generator, and the third electric motor MG3 can be operated as a prime mover with the generated electric power, thereby achieving series traveling. In the series mode, torque vibrations of the engine 20 can be prevented from being transmitted to the front drive shaft 38. Therefore, the vehicle body can be less likely to vibrate when the vehicle 8 is traveling with the engine 20 running.

[0067] Furthermore, according to this embodiment, the differential mechanism 32 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 allows for downsizing when the mechanical point in the differential mechanism 32 is set by the reduction ratio.

[0068] Furthermore, according to this embodiment, the first electric motor MG1 is disposed on a rotational axis (second axis CS2) that is different from the rotational axis (first axis CS1) of the differential mechanism 32, and is coupled to the first rotating element RE1 via the power transmission member 40. This makes it possible to prevent the size of the first electric motor MG1 from becoming larger in the direction of the first axis CS1.

[0069] Furthermore, according to this embodiment, the brake BR that stops the rotation of the first rotating element RE1 is further provided, which allows the vehicle to run as a BEV using the second electric motor MG2 as a power source with the engine 20 stopped, for example, at the maximum torque of the second electric motor MG2.

[0070] 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.

[0071] FIG. 9 is a diagram illustrating a schematic configuration of a vehicle 100 equipped with a vehicle drive system 110 (including a front drive unit 110f and a rear drive unit 110r) to which the present invention is applied. In FIG. 9 , the front power transmission device 130 of the front drive unit 110f further includes a clutch CL that interrupts power transmission between the differential mechanism 32 and the front drive shaft 38. The clutch CL is provided, for example, on the front counter gear 34. The clutch CL is an engagement device that is operated by, for example, an electric or hydraulic actuator to connect and disconnect the power transmission path between the carrier C of the differential mechanism 32 and the front differential gear 36. The clutch CL functions as a clutch mechanism that selectively interrupts power transmission between the carrier C and the front drive shaft 38. The electronic control unit 70 outputs various command signals to the clutch CL, which is one of various devices equipped in the vehicle 100. The clutch control command signal ScI is a request signal for controlling the clutch CL to an engaged state or a disengaged state. The clutch CL is a clutch mechanism that, when in a released state, interrupts the transmission of power between the third rotating element RE3 and the front drive shaft 38.

[0072] In the vehicle drive system 110, the parking mechanism PLC is provided in the rear power transmission device 50, which is not provided with the clutch CL.

[0073] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained.

[0074] Furthermore, according to this embodiment, a clutch CL is further provided to interrupt power transmission between the third rotating element RE3 and the front drive shaft 38. This prevents power loss due to drag of components upstream of the front drive shaft 38, such as the second electric motor MG2, when the vehicle 100 is driven in a mode that drives the rear drive shaft 58, such as Mode1_MG3 or Mode2. This is particularly useful when frequently using a mode in which the second electric motor MG2 is stopped and the vehicle is driven using the third electric motor MG3 as a power source, such as Mode1_MG3 or Mode2. For example, in a PHEV equipped with a battery 64 with a larger capacity than that of an HEV, it is expected that BEV driving using Mode1_MG3 will be frequently used.

[0075] Furthermore, according to this embodiment, in addition to the clutch CL provided in the front power transmission device 130, a parking mechanism PLC is further provided in the rear power transmission device 50, which is not provided with the clutch CL. As a result, the clutch CL and the parking mechanism PLC are not arranged together on the front drive shaft 38 side, i.e., in the front power transmission device 130, and therefore the vehicle drive device 110 can be prevented from becoming larger in size.

[0076] FIG. 10 is a diagram illustrating a schematic configuration of a vehicle 200 equipped with a vehicle drive system 210 (including a front drive unit 210f and a rear drive unit 210r) to which the present invention is applied. In FIG. 10 , the rear power transmission device 250 of the rear drive unit 210r further includes a clutch CL that interrupts power transmission between the output gear 52 and the rear drive shaft 58. The clutch CL is provided, for example, on the rear counter gear 54. The clutch CL is an engagement device that is operated by, for example, an electric or hydraulic actuator to connect and disconnect the power transmission path between the output gear 52 and the rear differential gear 56. The clutch CL functions as a clutch mechanism that selectively interrupts power transmission between the third electric motor MG3 and the rear drive shaft 58. The clutch CL is a clutch mechanism that interrupts power transmission between the third electric motor MG3 and the rear drive shaft 58 when disengaged.

[0077] In the vehicle drive system 210, the parking mechanism PLC is provided in the front power transmission device 230, which is not provided with a clutch CL. One end of the parking mechanism PLC is coupled to a non-rotating member (not shown). Additionally, the parking mechanism PLC is operated, for example, by an electric actuator or a manually operated mechanical actuator, to engage or disengage the other end with the carrier C of the differential mechanism 32. The non-rotating member to which the parking mechanism PLC is coupled is, for example, a case that houses the front power transmission device 230. The parking mechanism PLC is a known parking lock device that switches between, for example, a parking lock state in which the carrier C is mechanically fixed so as to be non-rotatable, and a non-parking lock state in which the carrier C is rotatable. The carrier C is a rotating member that rotates together with the front drive shaft 38. The carrier C and the front drive shaft 38 are selectively non-rotatable or rotatable by the parking mechanism PLC.

[0078] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained.

[0079] Furthermore, according to this embodiment, a clutch CL is further provided to interrupt the power transmission between the third electric motor MG3 and the rear drive shaft 58. This prevents power loss due to drag of the third electric motor MG3 when the vehicle 200 is driven in a mode that drives the front drive shaft 38, such as Mode1_MG2, Mode1_MG2_BRon, or Mode 4.

[0080] Furthermore, according to this embodiment, in addition to the clutch CL provided in the rear power transmission device 250, a parking mechanism PLC is further provided in the front power transmission device 230, which is not provided with the clutch CL. As a result, the clutch CL and the parking mechanism PLC are not arranged together on the rear drive shaft 58 side, that is, in the rear power transmission device 250, and therefore the size of the vehicle drive device 210 can be prevented from becoming large.

[0081] 11 is a diagram illustrating a schematic configuration of a vehicle 300 equipped with a vehicle drive system 310 (including a front drive unit 310f and a rear drive unit 310r) to which the present invention is applied. In FIG. 11, a front power transmission device 330 of the front drive unit 310f includes a differential mechanism 332. The differential mechanism 332 and a front differential gear 36 are connected via a front counter gear 34, similar to the front power transmission device 30 of the first embodiment described above.

[0082] The differential mechanism 332 is a single-pinion planetary gear device having 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 20 and a first electric motor MG1 are connected to the carrier C. The first electric motor MG1 is connected to the carrier C via a power transmission member 40. The ring gear R meshes with a front counter gear 34. A front drive shaft 38 is connected to the ring gear R. One end of a brake BR is connected to the output shaft of the engine 20 or the carrier C, and the other end is connected to a non-rotating member (not shown) such as a case.

[0083] FIG. 12 is a nomographic diagram illustrating the configuration of the vehicle drive device 310. In FIG. 12, the differential mechanism 332 of the front drive unit 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 332 is coupled to an actuator. Expressed using the nomographic diagram, the first rotating element RE1 is the carrier C. The engine 20 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 38, i.e., the front wheels 12f, are coupled to the third rotating element RE3. The brake BR is a brake mechanism that stops the 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, and therefore a description thereof will be omitted.

[0084] 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 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3.

[0085] In the differential mechanism 332, the rotational speed of the third rotating element RE3, which is the output element, is set to the speed-up side, i.e., the overdrive (O / D) side, relative to the engine rotational speed Ne at the mechanical point. That is, the differential mechanism 332 has a mechanical point set by a speed-up ratio. Therefore, in the vehicle drive system 310, Mode 3 is an O / D input split mode, and Mode 4 is an O / D output split mode.

[0086] As described above, according to this embodiment, a plurality of drive modes can be realized by controlling the engine 20 and simultaneously transmitting and receiving electric power to the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3. Therefore, similar to the first embodiment, when the vehicle 300 is driven with the engine 20 running, the vehicle body can be made less likely to vibrate.

[0087] Furthermore, according to this embodiment, the differential mechanism 332 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 allows for downsizing when the mechanical point in the differential mechanism 332 is set by the speed-up ratio.

[0088] 13 is a diagram illustrating a schematic configuration of a vehicle 400 equipped with a vehicle drive system 410 (including a front drive unit 410f and a rear drive unit 410r) to which the present invention is applied. In FIG. 13, a front power transmission device 430 of the front drive unit 410f includes a differential mechanism 432. The differential mechanism 432 and the front differential gear 36 are connected via the front counter gear 34, similar to the front power transmission device 30 of the first embodiment described above.

[0089] The differential mechanism 432 is a double-pinion planetary gear device having a sun gear S, pinions Pa and Pb, a carrier C, and a ring gear R. The pinions Pa and Pb are pairs of pinions that mesh with each other. A second electric motor MG2 is connected to the sun gear S. The engine 20 and a first electric motor MG1 are connected to the carrier C. The first electric motor MG1 is connected to the carrier C via a power transmission member 40. The ring gear R meshes with the front counter gear 34. A front drive shaft 38 is connected to the ring gear R. One end of the brake BR is connected to the output shaft of the engine 20 or the carrier C, and the other end is connected to a non-rotating member (not shown) such as a case.

[0090] FIG. 14 is a nomographic diagram illustrating the configuration of the vehicle drive device 410. In FIG. 14, the differential mechanism 432 of the front drive unit 410f 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 432 is coupled to an actuator. Expressed using the nomographic diagram, the first rotating element RE1 is the carrier C. The engine 20 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 38, i.e., the front wheels 12f, are coupled to the third rotating element RE3. The brake BR is a brake mechanism that stops the rotation of the first rotating element RE1 when engaged. The rear drive unit 410r is the same as the rear drive unit 10r of the first embodiment, and therefore a description thereof will be omitted.

[0091] Similar to the vehicle drive device 10 of the first embodiment described above, the vehicle drive device 410 is capable of switching the drive mode between multiple modes by controlling the engine 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3.

[0092] In the differential mechanism 432, 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 at the mechanical point. That is, the mechanical point of the differential mechanism 432 is set by the reduction ratio. Therefore, in the vehicle drive system 410, Mode 3 is a U / D input split mode, and Mode 4 is a U / D output split mode.

[0093] As described above, according to this embodiment, a plurality of drive modes can be realized by controlling the engine 20 and simultaneously transmitting and receiving electric power to the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3. Therefore, similar to the first embodiment, when the vehicle 400 is driven with the engine 20 running, the vehicle body can be made less likely to vibrate.

[0094] Furthermore, according to this embodiment, the differential mechanism 432 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 allows for downsizing when the mechanical point in the differential mechanism 432 is set by the reduction ratio.

[0095] 15 is a diagram illustrating the schematic configuration of a vehicle 500 equipped with a vehicle drive system 510 (including a front drive unit 510f and a rear drive unit 510r) to which the present invention is applied. In FIG. 15, a front power transmission device 530 of the front drive unit 510f includes a differential mechanism 532. The differential mechanism 532 and the front differential gear 36 are connected via the front counter gear 34, similar to the front power transmission device 30 of the first embodiment described above.

[0096] The differential mechanism 532 is a double-pinion planetary gear device having 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. The engine 20 and a first electric motor MG1 are connected to the ring gear R. The first electric motor MG1 is connected to the ring gear R via a power transmission member 40. The carrier C meshes with the front counter gear 34. A front drive shaft 38 is connected to the carrier C. One end of the brake BR is connected to the ring gear R, and the other end is connected to a non-rotating member (not shown), such as a case.

[0097] FIG. 16 is a nomographic diagram illustrating the configuration of the vehicle drive device 510. In FIG. 16, the differential mechanism 532 of the front drive unit 510f 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 532 is coupled to an actuator. Expressed using the nomographic diagram, the first rotating element RE1 is the ring gear R. The engine 20 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 carrier C. The front drive shaft 38, i.e., the front wheels 12f, are coupled to the third rotating element RE3. The brake BR is a brake mechanism that stops the rotation of the first rotating element RE1 when engaged. The rear drive unit 510r is the same as the rear drive unit 10r of the first embodiment, and therefore a description thereof will be omitted.

[0098] Similar to the vehicle drive device 10 of the first embodiment described above, the vehicle drive device 510 is capable of switching the drive mode between multiple modes by controlling the engine 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3.

[0099] In the differential mechanism 532, the rotational speed of the third rotating element RE3, which is the output element, is set to the speed-up side, i.e., the overdrive (O / D) side, relative to the engine rotational speed Ne at the mechanical point. That is, the mechanical point of the differential mechanism 532 is set by the speed-up ratio. Therefore, in the vehicle drive device 510, Mode 3 is an O / D input split mode, and Mode 4 is an O / D output split mode.

[0100] As described above, according to this embodiment, a plurality of drive modes can be realized by controlling the engine 20 and simultaneously transmitting and receiving electric power to the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3. Therefore, similar to the first embodiment, when the vehicle 500 is driven with the engine 20 running, the vehicle body can be made less likely to vibrate.

[0101] Furthermore, according to this embodiment, the differential mechanism 532 is a double-pinion planetary gear device, in which the first rotating element RE1 is the ring gear R, the second rotating element RE2 is the sun gear S, and the third rotating element RE3 is the carrier C. This allows for downsizing when the mechanical point in the differential mechanism 532 is set by the speed-up ratio.

[0102] FIG. 17 is a nomographic diagram illustrating the configuration of a vehicle drive device 610 (including a front drive unit 610f and a rear drive unit 610r). In FIG. 17, the vehicle drive device 610 differs from the vehicle drive device 10 in the configuration of the vehicle drive device 10 in the first embodiment described above in that the brake BR provided in the vehicle drive device 10 is replaced with a one-way clutch OWC. The one-way clutch OWC may be used instead of the brake BR as a brake mechanism that stops rotation of the first rotating element RE1 by being engaged. Similarly, the one-way clutch OWC may be used instead of the brake BR in the vehicle drive devices 110, 210, 310, 410, and 510 in the second to sixth embodiments described above.

[0103] 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 ring gear R, i.e., the first rotating element RE1, of the differential mechanism 32, 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 20 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 20 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 disengaged.

[0104] FIG. 18 is a nomographic diagram illustrating a BEV mode, i.e., Mode1_MG2_OWC, in which the second electric motor MG2 generates torque with the one-way clutch OWC engaged. Mode1_MG2_OWC is one of Modes 1 that enable BEV driving. In FIG. 18, Mode1_MG2_OWC is included in a plurality of modes that enable switching of the drive mode. Mode1_MG2_OWC is a mode in which the engine 20 is stopped and the second electric motor MG2 generates torque 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 that BEV driving by the second electric motor MG2 is enabled using the power of the battery 64. At this time, BEV driving is enabled with the second electric motor MG2 at its maximum torque. In Mode1_MG2_OWC, it is also possible to increase the drive torque by causing the third electric motor MG3 to generate torque, as shown in Fig. 18. Note that the vehicle drive device 610 includes, as Mode 1 that enables BEV driving, Mode1_MG3, which is a mode in which the engine 20 is stopped and torque is generated by the third electric motor MG3 to perform BEV driving.

[0105] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained.

[0106] 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.

[0107] For example, in the differential mechanism 32 of the above-described Examples 1-3, 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 20 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.

[0108] In the differential mechanism 332 of the fourth embodiment described above, 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 38 is connected to the sun gear S.

[0109] In the differential mechanism 432 of the fifth embodiment described above, 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 20 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.

[0110] In the differential mechanism 532 of the sixth 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 38 is connected to the sun gear S.

[0111] Here, as shown in the above-mentioned Examples 1-7, 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.

[0112] In the above-described Examples 1-7, 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 intermediate gear 40a and the first rotating element RE1 are connected via a counter gear that meshes with both of them.

[0113] Furthermore, in the above-described Examples 1-7, the first electric motor MG1 may be arranged on the same rotational axis as the engine 20 and the second electric motor MG2. In other words, the first electric motor MG1 may be arranged on the first axis CS1, which is the rotational axis of the differential mechanism 32. Even in this case, a certain effect can be obtained in that the vehicle body can be made less likely to vibrate when traveling with the engine 20 running.

[0114] In addition, in the above-described Examples 1 to 6, 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.

[0115] In the seventh 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.

[0116] Furthermore, the parking mechanism PLC and the clutch CL shown in the second and third embodiments may be integrated into either the front power transmission device or the rear power transmission device, which still provides a certain effect of making it difficult for the vehicle body to vibrate when traveling with the engine 20 running.

[0117] Furthermore, the clutch CL shown in the second and third embodiments may be disposed in either the front power transmission device 730 or the rear power transmission device 750, as shown in a vehicle drive system 710 provided in a vehicle 700 in FIG. 19. In FIG. 19, the vehicle drive system 710, which includes a front drive unit 710f and a rear drive unit 710r, is provided with a front power transmission device 730 and a rear power transmission device 750. The clutch CL includes a first clutch CL1 provided in the front power transmission device 730 and a second clutch CL2 provided in the rear power transmission device 750. The first clutch CL1 is a first clutch mechanism that, when disengaged, interrupts power transmission between the third rotating element RE3 and the front drive shaft 38, and is a clutch mechanism similar to the clutch CL of the second embodiment. The second clutch CL2 is a second clutch mechanism that, when disengaged, interrupts power transmission between the third electric motor MG3 and the rear drive shaft 58, and is the same clutch mechanism as the clutch CL in the third embodiment. This prevents power loss due to drag of a component upstream of the front drive shaft 38, such as the second electric motor MG2, when the vehicle 700 is driven in a mode that drives the rear drive shaft 58, such as Mode1_MG3 or Mode 2. Furthermore, when the vehicle 700 is driven in a mode that drives the front drive shaft 38, such as Mode1_MG2, Mode1_MG2_BRon, Mode1_MG2_OWC, or Mode 4, power loss due to drag of the third electric motor MG3 can be prevented.

[0118] In addition, in the above-described Examples 1 to 7, one of the front wheels 12f and the rear wheels 12r to which the power of the engine 20 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 58, and the second drive shaft may be the front drive shaft 38.

[0119] Furthermore, in the above-mentioned Examples 1-7, since it is expected that the PHEV will make heavy use of BEV driving using Mode 1_MG3, the drive unit equipped with the third electric motor MG3 is used as the main engine, but in the HEV, the drive unit equipped with the engine 20 or the second electric motor MG2 may be used as the main engine.

[0120] 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.

[0121] 10: Vehicle drive device 12f: Front wheels 12r: Rear wheels 20: Engine 32: Differential mechanism (single pinion planetary gear device) S: Sun gear (second rotating element) C: Carrier (third rotating element, rotating member that rotates together with first drive shaft) R: Ring gear (first rotating element) 38: Front drive shaft (first drive shaft) 40: Power transmission member 52: Output gear (rotating member that rotates together with second drive shaft) 58: Rear drive shaft (second drive shaft) 110: Vehicle drive device 210: Vehicle drive device 310: Vehicle drive device 332: Differential mechanism (single pinion planetary gear device) S: Sun gear (second rotating element) C: Carrier (first rotating element) R: Ring gear (third rotating element) 410: Vehicle drive device 432: Differential mechanism (double pinion planetary gear device) S: Sun gear (second rotating element) C: Carrier (first rotating element) R: Ring gear (third rotating element) 510: Vehicle drive device 532: 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) 610: Vehicle drive device 710: Vehicle drive device BR: Brake (brake mechanism) CL: Clutch (clutch mechanism) CL1: First clutch (first clutch mechanism) CL2: Second clutch (second clutch mechanism) CS1: First shaft center (rotational shaft center of planetary gear device) CS2: Second shaft center (rotational shaft center of first electric motor) MG1: First electric motor MG2: Second electric motor MG3: Third electric motor OWC: One-way clutch (brake mechanism) PLC: Parking mechanism RE1: First rotating element RE2: Second rotating element RE3: Third rotating element

Claims

1. A vehicle drive device comprising an engine, a first electric motor, a second electric motor, a third electric motor, a differential mechanism, a first drive shaft that drives one of the front wheels and the rear wheels, and a second drive shaft that drives the other of the front wheels and the rear wheels, wherein the differential mechanism has three rotating elements: a first rotating element, a second rotating element, and a third rotating element, wherein 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, and the vehicle drive device is characterized in that the second drive shaft is connected to the third electric motor.

2. The vehicle drive device described in claim 1, characterized in that the differential mechanism 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.

3. The vehicle drive device according to claim 1, characterized in that the differential mechanism 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, and the third rotating element is the other of the sun gear and the ring gear.

4. The vehicle drive device described in claim 1, characterized in that the differential mechanism 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, and the third rotating element is the ring gear.

5. The vehicle drive device according to claim 1, characterized in that the differential mechanism 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, and the third rotating element is the other of the sun gear and the carrier.

6. A vehicle drive device as described in any one of claims 2 to 5, characterized in that the first electric motor is arranged on a rotational axis different from that of the planetary gear device, and the first electric motor is connected to the first rotating element via a power transmission member.

7. A vehicle drive device according to any one of claims 1 to 5, further comprising a brake mechanism that stops rotation of the first rotating element when brought into an engaged state.

8. A vehicle drive device as described in any one of claims 1 to 5, further comprising a clutch mechanism that, when released, cuts off power transmission between the third rotating element and the first drive shaft.

9. A vehicle drive device as described in claim 8, further comprising a parking mechanism that switches between a parking lock state in which the rotating member that rotates together with the second drive shaft is mechanically fixed so as not to rotate, and a non-parking lock state in which the rotating member is rotatable.

10. A vehicle drive device as described in any one of claims 1 to 5, further comprising a clutch mechanism that, when released, cuts off power transmission between the third electric motor and the second drive shaft.

11. A vehicle drive device as described in claim 10, further comprising a parking mechanism that switches between a parking lock state in which a rotating member that rotates together with the first drive shaft is mechanically fixed so as not to rotate, and a non-parking lock state in which the rotating member is rotatable.

12. A vehicle drive device as described in any one of claims 1 to 5, further comprising: a first clutch mechanism that, when released, cuts off the power transmission between the third rotating element and the first drive shaft; and a second clutch mechanism that, when released, cuts off the power transmission between the third electric motor and the second drive shaft.

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