Vehicle drive apparatus

Abstract

To provide a vehicle drive apparatus which enables series traveling to be performed, and in addition, which can suppress occurrence of gear rattle noise when the series traveling is performed.SOLUTION: A differential mechanism includes three rotary elements consisting of a first rotary element, a second rotary element, and a third rotary element. An engine and a first electric motor are connected to the first rotary element of the differential mechanism, a second electric motor is connected to the second rotary element, and a first drive shaft for driving one of front and rear wheels is connected to the third rotary element. Further, a third electric motor is connected to a second drive shaft for driving the other of the front and rear wheels. When series traveling is performed such that the first electric motor is operated as a power generator by operation of the engine, and that the third electric motor is operated as a prime mover by power generated by the first electric motor, an electronic controller causes the second electric motor to generate additional torque, thereby reducing gear backlash in the differential mechanism and suppressing occurrence of gear rattle noise.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive system that includes an engine, three electric motors, a differential mechanism, drive shafts that drive front and rear wheels, and a control device. [Background technology]

[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 and rear wheels, a second drive shaft that drives the other of the front and rear wheels, and a control device. For example, Patent Document 1 discloses such a vehicle drive 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 8,512,189 Summary of the Invention [Problem to be solved by the invention]

[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 the torque vibration of the engine is transmitted to the first drive shaft, which may cause the vehicle body to vibrate.

[0005] In order to suppress the vehicle body vibrations, a configuration in which engine torque vibrations are not transmitted to the first drive shaft can be considered. For example, a 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, a second drive shaft that drives the other of the front wheels and the rear wheels, and a control device, wherein the differential mechanism has three rotating elements: a first rotating element, a second rotating element, and a third rotating element, and 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, the first drive shaft is connected to the third rotating element, and the third electric motor is connected to the second drive shaft.

[0006] The vehicle drive device configuration controls the engine and simultaneously controls the first, second, and third electric motors to exchange electric power, enabling so-called series running, in which the first electric motor connected to the same rotating element as the engine is operated as a generator and the third electric motor is operated as a prime mover with the generated electric power to drive the second drive shaft when the vehicle is running with the engine. In series running, torque vibration of the engine is prevented from being transmitted to the first drive shaft, making it possible to reduce the likelihood of the vehicle body vibrating when the vehicle is running with the engine.

[0007] Here, when a vehicle equipped with the vehicle drive device is running in series, the pressing force between the gears of the differential mechanism becomes smaller, and there is a risk that gear rattle noise will occur due to explosive vibrations of the engine.

[0008] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle drive device that is configured to enable series driving and can suppress the generation of gear rattle noise when series driving is performed. [Means for solving the problem]

[0009] The gist of the first invention is a vehicle drive device including: (a) 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, a second drive shaft that drives the other of the front wheels and the rear wheels, and a control device; (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; (d) the third electric motor is connected to the second drive shaft; and (e) the control device is configured to generate torque in the second electric motor when performing series driving in which the engine is operated to operate the first electric motor as a generator while the third electric motor is operated as a prime mover using the generated power of the first electric motor.

[0010] Furthermore, a second invention is a vehicle drive device according to the first invention, wherein the control device is configured to cause the first rotating element to generate a positive torque in the second electric motor in the same direction as the torque of the engine when the first rotating element is operating when the series running is performed.

[0011] Furthermore, a third invention is a vehicle drive device according to the first invention, wherein the control device is configured to cause the first rotating element to generate a negative torque in the second electric motor in the opposite direction to the torque of the engine when the first rotating element is operating when the series running is performed.

[0012] A fourth aspect of the present invention is a vehicle drive device according to the first aspect of the present invention, wherein the control device is configured to, when performing the series running, cause the second electric motor to generate a positive torque in the same direction as the torque of the engine when the vehicle is accelerating, on the first rotating element, and a negative torque in the opposite direction to the torque of the engine when the vehicle is decelerating, on the first rotating element.

[0013] A fifth aspect of the present invention is a vehicle drive device according to any one of the first to fourth aspects of the present invention, wherein the control device is configured to increase the torque generated by the second electric motor as the torque of the engine increases when the series running is performed. [Effects of the Invention]

[0014] According to the first aspect of the present invention, the differential mechanism has three rotating elements: a first rotating element, a second rotating element, and a third rotating element. 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. The third electric motor is connected to the second drive shaft. The control device is configured to cause the second electric motor to generate torque when performing series running in which the engine is operated to operate the first electric motor as a generator and the third electric motor is operated as a prime mover using the generated power of the first electric motor. This makes it possible to perform series running in which the first electric motor, which is connected 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 power to drive the second drive shaft. This prevents torque vibrations of the engine from being transmitted to the first drive shaft, thereby reducing the likelihood of vibration of the vehicle body. Furthermore, when the series running is performed, the pressing force between the gears of the differential mechanism becomes smaller, and there is a risk that gear rattle noise will occur due to the explosive vibration of the engine. However, by generating torque in the second electric motor, the gear rattle can be eliminated, and the occurrence of gear rattle noise can be suppressed.

[0015] According to the second aspect of the present invention, the control device is configured to, when the series running is performed, cause the second electric motor to generate a positive torque in the same direction as the torque of the engine when the first rotating element is operating, thereby making it possible to suitably eliminate backlash in the gears when the vehicle is accelerating.

[0016] According to the third aspect of the present invention, the control device is configured to, when performing the series running, cause the second electric motor to generate a negative torque opposite to the torque of the engine when the first rotating element is operating, thereby making it possible to suitably eliminate backlash in the gears when the vehicle is decelerating.

[0017] According to the fourth aspect of the present invention, the control device is configured to, during series running, cause the second electric motor to generate a positive torque in the same direction as the torque of the engine operating on the first rotating element when the vehicle is accelerating, and a negative torque in the opposite direction to the torque of the engine operating on the first rotating element when the vehicle is decelerating, thereby making it possible to preferably eliminate backlash in the gears regardless of whether the vehicle is accelerating or decelerating.

[0018] According to the fifth aspect of the present invention, the control device is configured to increase the torque generated by the second electric motor as the torque of the engine increases, thereby making it possible to suitably eliminate backlash in the gears regardless of the magnitude of the torque of the engine. [Brief explanation of the drawings]

[0019] [Figure 1] 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. [Figure 2] FIG. 2 is a nomographic diagram illustrating the configuration of the vehicle drive device. [Figure 3] FIG. 2 is a diagram illustrating a main part of a control system for various controls in the vehicle drive device. [Figure 4] 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 5] 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 6] 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 7] 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 8] 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 9] 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 10] FIG. 10 is a diagram showing an example of a drive mode switching map used for drive mode switching control, which is used in charge consumption running. [Figure 11] FIG. 10 is a diagram showing an example of a drive mode switching map used for drive mode switching control, which is used in charge-maintenance running. [Figure 12] 11 is a diagram showing an example of a drive mode switching map used for drive mode switching control, which is used in charge consumption running, and in which the drive force in FIG. 10 is replaced with the accelerator opening. [Figure 13] FIG. 12 is a diagram showing an example of a drive mode switching map used for drive mode switching control, which is used in charge-maintenance running, and in which the drive force in FIG. 11 is replaced with the accelerator opening. [Figure 14]10 is a nomographic diagram illustrating a case where a positive torque in the same direction as the torque of the engine during operation is generated in the second electric motor by the first rotating element in the backlash elimination control performed by the electronic control device. FIG. [Figure 15] 15 is a schematic diagram illustrating the operating state of the differential mechanism in the case of FIG. 14. FIG. [Figure 16] FIG. 15 is a diagram showing torque acting on the crankshaft of the engine in the case of FIG. 14. [Figure 17] 10 is a nomographic diagram illustrating a case where a negative torque in a direction opposite to the torque of the engine during operation is generated in the second electric motor by the first rotating element in the backlash elimination control performed by the electronic control device. FIG. [Figure 18] 18 is a schematic diagram illustrating the operating state of the differential mechanism in the case of FIG. 17. FIG. [Figure 19] FIG. 18 is a diagram showing torque acting on the crankshaft of the engine in the case of FIG. 17. [Figure 20] 10 is an example of a map of setting values ​​of torque to be generated by a second electric motor in backlash elimination control performed by an electronic control device. [Figure 21] 1 is an example of a flowchart illustrating a main part of the control operation of the electronic control device, and is a flowchart illustrating the control operation of backlash elimination control performed by the electronic control device. [Figure 22] FIG. 10 is a diagram showing an example of a time chart when the electronic control device performs backlash elimination control. [Figure 23] 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 24] 24 is a nomographic diagram illustrating the configuration of the vehicle drive device of FIG. 23. FIG. [Figure 25] FIG. 24 is a nomographic diagram illustrating a case where a positive torque in the same direction as the torque of the engine during operation is generated in the second electric motor by the first rotating element in the backlash elimination control performed by the electronic control device provided in the vehicle drive device of FIG. 23. [Figure 26] 26 is a schematic diagram illustrating the operating state of the differential mechanism in the case of FIG. 25. FIG. [Figure 27]24 is an example of a map of setting values ​​of torque to be generated by a second electric motor in backlash eliminating control performed by an electronic control device provided in the vehicle drive device of FIG. 23. [Figure 28] 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, the diagram illustrating a vehicle different from the vehicle of FIG. [Figure 29] FIG. 29 is a nomographic diagram illustrating the configuration of the vehicle drive device of FIG. 28. [Figure 30] FIG. 29 is a nomographic diagram illustrating a case where a positive torque in the same direction as the torque of the engine during operation is generated in the second electric motor by the first rotating element in the backlash elimination control performed by the electronic control device provided in the vehicle drive device of FIG. [Figure 31] 31 is a schematic diagram illustrating the operating state of the differential mechanism in the case of FIG. 30. FIG. [Figure 32] 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 33] 33 is a nomographic diagram showing the configuration of the vehicle drive device of FIG. 32. FIG. [Figure 34] FIG. 33 is a nomographic diagram illustrating a case where a positive torque in the same direction as the torque of the engine during operation is generated in the second electric motor by the first rotating element in the backlash elimination control performed by the electronic control device provided in the vehicle drive device of FIG. [Figure 35] 35 is a schematic diagram illustrating the operating state of the differential mechanism in the case of FIG. 34. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0021] FIG. 1 is a diagram illustrating the 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 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The engine 20 and the second electric motor MG2 are each disposed on a first axis CS1, which is the rotation axis of the differential mechanism 32. The first electric motor MG1 is disposed on a second axis CS2. The second axis CS2 is a rotation 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 as, for example, 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.

[0028] 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 rotatable or non-rotatable by the brake BR.

[0029] The rear power transmission device 50 is provided in a 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 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 drive shaft 58 is 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.

[0030] 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 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 58. The output gear 52 and the rear drive shaft 58 are selectively non-rotatable or rotatable by the parking mechanism PLC.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] FIG. 3 is a diagram illustrating essential parts of a control system for various controls in the vehicle drive system 10. In FIGS. 1 and 3, 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 pre-stored in the ROM. For example, the electronic control unit 70 controls the outputs of the engine 20, 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 divided into a hybrid control ECU 72 (see "PHEV-ECU" in FIG. 3), an engine control ECU 74 (see "ENG-ECU" in FIG. 3), an electric motor control ECU 76 (see "MG-ECU" in FIG. 3), and the like, as needed.

[0035] The hybrid control ECU 72 receives various signals based on detection signals from various sensors provided in the vehicle 8. The various sensors include, for example, an accelerator pedal position sensor 80, a vehicle speed sensor 81, a battery sensor 82, a BEV switch 83, and a shift position sensor 84. The various sensors also include, for example, a first electric motor rotation sensor 85, a second electric motor rotation sensor 86, and a third electric motor rotation sensor 87, each of which may be a resolver. The various sensors also include, for example, an engine rotation speed sensor 88, a brake switch 89, a brake operation amount sensor 90, a crawl switch 91, and a traction switch 92. The various signals also include, for example, an accelerator pedal position θacc, a vehicle speed V, a signal for calculating the charge state of charge (SOC), a BEV-on signal BEVon, and a shift operation position POSop. The various signals also include, for example, a first electric motor rotation speed Nmg1, a second electric motor rotation speed Nmg2, and a third electric motor rotation speed Nmg3. The various signals include, for example, an engine rotation speed Ne, a brake-on signal BPon, a brake operation amount θbp, a crawl-on signal CRon, a traction-on signal TRon, and the like.

[0036] The BEV switch 83 is a switch operated by the driver when BEV driving is required. When the BEV switch 83 is operated, the engine 20 is not started, and the vehicle is driven in BEV mode using only the power of the battery 64. The crawl switch 91 is a switch operated by the driver when a situation is anticipated in which the vehicle will be driven at an extremely low speed and with a high load on a rocky road, for example. The towing switch 92 is a switch operated by the driver when the vehicle 8 is driven with a towed vehicle coupled to the rear of the vehicle.

[0037] The accelerator opening θacc is the amount of accelerator operation by the driver, which indicates the magnitude of the driver's acceleration operation. The vehicle speed V is the speed of the vehicle 8. The signals for calculating the state of charge SOC are the battery charge / discharge current and battery voltage detected by the battery sensor 82. The state of charge SOC is the remaining charge of the battery 64 and is calculated by the electronic control unit 70 based on the battery charge / discharge current and battery voltage. The battery sensor 82 also detects the battery temperature. The BEV-on signal BEVon is a signal indicating that the BEV switch 83 has been operated by the driver. The shift operation position POSop is the lever position of the shift operation device, such as "P," "R," "N," or "D." The first electric motor rotation speed Nmg1 is the rotation speed of the first electric motor MG1. The second electric motor rotation speed Nmg2 is the rotation speed of the second electric motor MG2. The third electric motor rotation speed Nmg3 is the rotation speed of the third electric motor MG3. The engine rotation speed Ne is the rotation speed of the engine 20. The brake-on signal BPon is a signal indicating that the brake pedal for applying the wheel brakes is being operated by the driver. The brake operation amount θbp is a signal indicating the magnitude of the brake pedal depression operation by the driver, i.e., the magnitude of the brake operation, and is synonymous with the brake pedal depression force. The crawl-on signal CRon is a signal indicating that the crawl switch 91 has been operated by the driver. The tow-on signal TRon is a signal indicating that the tow switch 92 has been operated by the driver.

[0038] The engine control ECU 74 receives input of an air-fuel ratio A / F and the like based on detection signals from an air-fuel ratio sensor 93 and the like provided on the vehicle 8. The motor control ECU 76 receives input of a first electric motor rotation angle θmg1, a second electric motor rotation angle θmg2, a third electric motor rotation angle θmg3 and the like based on detection signals from a first electric motor rotation sensor 85, a second electric motor rotation sensor 86, a third electric motor rotation sensor 87, and the like.

[0039] The air-fuel ratio A / F is a signal that represents the state of the air-fuel ratio in the exhaust gas. The first electric motor rotation angle θmg1 is a signal that represents the rotational position, which is the rotational angle of the rotor of the first electric motor MG1 from a predetermined reference position. The second electric motor rotation angle θmg2 is a signal that represents the rotational position, which is the rotational angle of the rotor of the second electric motor MG2 from a predetermined reference position. The third electric motor rotation angle θmg3 is a signal that represents the rotational position, which is the rotational angle of the rotor of the third electric motor MG3 from a predetermined reference position.

[0040] The hybrid control ECU 72 outputs various command signals to the engine control ECU 74. The various command signals to the engine control ECU 74 include, for example, a command signal for a target engine torque Tetgt, a fuel cut request signal FCreq for requesting a fuel cut operation, etc. The hybrid control ECU 72 also outputs various command signals to the electric motor control ECU 76. The various command signals to the electric motor control ECU 76 include, for example, a command signal for a target first electric motor torque Tmg1tgt, a command signal for a target second electric motor torque Tmg2tgt, and a command signal for a target third electric motor torque Tmg3tgt, etc. The hybrid control ECU 72 also outputs a brake control command signal Sbr to the brake BR, etc.

[0041] The target engine torque Tetgt is a target value of the engine torque Te. The fuel cut operation is a control operation that cuts off the supply of fuel to the engine 20. The target first electric motor torque Tmg1tgt is a target value of the first electric motor torque Tmg1. The target second electric motor torque Tmg2tgt is a target value of the second electric motor torque Tmg2. The target third electric motor torque Tmg3tgt is a target value of the third electric motor torque Tmg3. 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).

[0042] The engine control ECU 74 outputs an engine control command signal Se and the like to the engine control device 60, etc. The engine control command signal Se is a command signal for controlling the engine 20, and includes command signals for the intake air amount Qair, the ignition timing TMig, the fuel injection amount Qfi, etc.

[0043] The motor control ECU 76 outputs a first motor control command signal Smg1, a second motor control command signal Smg2, a third motor control command signal Smg3, etc. to the inverter 62, etc. The first motor control command signal Smg1 is a command signal for controlling the first motor MG1 and includes command signals such as a first motor current Img1. The second motor control command signal Smg2 is a command signal for controlling the second motor MG2 and includes command signals such as a second motor current Img2. The third motor control command signal Smg3 is a command signal for controlling the third motor MG3 and includes command signals such as a third motor current Img3. The first motor current Img1 is a drive current for the first motor MG1. The second motor current Img2 is a drive current for the second motor MG2. The third motor current Img3 is a drive current for the third motor MG3.

[0044] The hybrid control ECU 72 determines various command signals based on the driver's intentions, such as the accelerator opening θacc and the brake operation amount θbp, the first electric motor rotation speed Nmg1, the second electric motor rotation speed Nmg2, the third electric motor rotation speed Nmg3, and the engine rotation speed Ne. For example, the hybrid control ECU 72 determines a brake control command signal Sbr to control the engagement and release states of the brake BR. The engine control ECU 74 determines an engine control command signal Se based on a command signal for a target engine torque Tetgt, a fuel cut request signal FCreq requesting a fuel cut operation, and the like. The engine control ECU 74 outputs the engine control command signal Se to control the engine 20. The electric motor control ECU 76 determines electric motor control command signals Smg1, Smg2, and Smg3 based on a target first electric motor torque Tmg1tgt, a target second electric motor torque Tmg2tgt, and a target third electric motor torque Tmg3tgt, etc. The electric motor control ECU 76 outputs electric motor control command signals Smg1, Smg2, Smg3 to control the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3.

[0045] As a result, the electronic control unit 70 is configured to control the engine 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3, and to switch the drive mode to one of a plurality of modes. Furthermore, when switching the drive mode, the electronic control unit 70 controls the brake BR to be engaged as necessary.

[0046] Here, the multiple modes into which the drive mode of the vehicle 8 can be switched will be described with reference to FIGS. 4 to 9. FIGS. 4 to 9 each show the relative rotational speeds of the rotational 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 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 carrier C, 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 ring gear R, which is the first rotational element RE1 connected to the engine 20 (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.

[0047] FIG. 4 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. 4, 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 perform 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 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.

[0048] FIG. 5 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. 5, 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 20 and causing the second electric motor MG2 to generate torque 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 possible with the second electric motor MG2 using power from the battery 64 without generating torque in the first electric motor MG1. In this case, BEV driving is possible with maximum torque from 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.

[0049] FIG. 6 is a nomographic diagram illustrating Mode1_MG3, a BEV mode in which the third electric motor MG3 generates torque with the brake BR engaged, which is yet another mode within Mode1 that enables BEV driving. In FIG. 6, Mode1_MG3 is included in 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 prevents drag from occurring in the engine 20 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.

[0050] 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 20 is stopped and the third electric motor MG3 is caused to generate torque to perform BEV running.

[0051] FIG. 7 is a nomographic diagram illustrating a first HEV mode, or 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. 7(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. 7(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. 7, 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 20 as a power source is possible.

[0052] In FIG. 7A, Mode 2 includes a mode in which the engine 20 is running 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 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, with the input from the engine 20 and the output from the rear wheels 12r, performing series mode operation. In Mode 2, power is converted between the engine 20 and the first electric motor MG1, and between the first electric motor MG1 and 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, 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 when used, for example, at low vehicle speeds and low loads where quietness is required. Furthermore, in Mode 2, for example, the setting of the operating point of the engine 20 is less subject to restrictions such as muffled noise, and therefore the engine 20 can be operated at an operating point that provides good fuel efficiency.

[0053] In FIG. 7(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 20. 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 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 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 20 is operating. The case where the engine 20 is operating is synonymous with the case where the engine 20 alone generates positive torque. In Mode 2 of FIG. 7(b), power is converted between the kinetic energy of the vehicle 8 and the third electric motor MG3, and power is converted between the third electric motor MG3 and 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.

[0054] FIG. 8 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. (a) of FIG. 8 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. 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 third electric motor MG3. In FIG. 8, Mode 3 is included in a plurality of modes that enable switching of the drive mode. Mode 3 is a mode that enables hybrid driving, i.e., HEV driving, and is an input split mode that enables 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 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).

[0055] The two-dot chain line A in FIG. 8(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 in the differential mechanism 32, 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 32 is set by the reduction ratio. In FIG. 8, Mode 3 is the U / D input split mode.

[0056] In (a) of Figure 8, 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, power is converted between the engine 20 and the second electric motor MG2, and between the second electric motor MG2 and the third electric motor MG3. Mode 3 has high transmission efficiency in the low vehicle speed and high load range, and is therefore useful for use in the low vehicle speed and high load range, for example.

[0057] In (b) of Fig. 8, 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, and therefore the electric power consumed in 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. 8, power conversion is performed between the kinetic energy of the vehicle 8 and the third electric motor MG3, and power conversion is performed between the third electric motor MG3 and the second electric motor MG2.

[0058] The vehicle drive device 10 is controlled to perform Mode 3 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 3 shown in (a) of Fig. 8 is not executed, the vehicle drive device 10 is controlled to perform Mode 3 shown in (b) of Fig. 8.

[0059] FIG. 9 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. 9 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. 9 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. 9, Mode 4 is included in a plurality of 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 released, 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. 9 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.

[0060] In (a) of Fig. 9, 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, power conversion is performed between the engine 20 and the first electric motor MG1, and power conversion is performed between the first electric motor MG1 and 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.

[0061] 9(b), 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 in FIG. 9(b), power conversion is performed between the engine 20 and the second electric motor MG2, and power conversion is performed between the second electric motor MG2 and the first electric motor MG1.

[0062] The vehicle drive device 10 is controlled to perform Mode 4 shown in (a) of Fig. 9 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. 9 is not executed, the vehicle drive device 10 is controlled to perform Mode 4 shown in (b) of Fig. 9.

[0063] The electronic control unit 70 is configured to switch the drive mode based on the vehicle speed V and the road load. The road load is, for example, the accelerator opening θacc. Alternatively, the road load is, for example, the required value of the driving force Fr based on the accelerator opening θacc and the vehicle speed V, or the actual value of the driving force Fr. For example, in the low vehicle speed / low load range, the first HEV mode, or Mode 2, is set as the drive mode (see Mode 2 shown in FIG. 7). In the low vehicle speed / high load range, the second HEV mode, or Mode 3, is set as the drive mode (see Mode 3 shown in FIG. 8). In the high vehicle speed range, the third HEV mode, or Mode 4, is set as the drive mode (see Mode 4 shown in FIG. 9).

[0064] Figures 10, 11, 12, and 13 each show an example of a drive mode switching map used for drive mode switching control. Each of these drive mode switching maps is a predetermined relationship on a two-dimensional coordinate system with vehicle speed V on the horizontal axis and road load on the vertical axis, with boundaries defining an area corresponding to one of a plurality of modes. In other words, each of these drive mode switching maps is a predetermined relationship for determining which drive mode to set.

[0065] Figures 10 and 11 show the case where the road load is set to driving force Fr, and Figures 12 and 13 show the case where the road load is set to accelerator pedal position θacc. Figure 12 shows the case where the driving force Fr in Figure 10 is replaced with accelerator pedal position θacc, and Figure 13 shows the case where the driving force Fr in Figure 11 is replaced with accelerator pedal position θacc. Figures 10 and 12 are drive mode switching maps used in CD (Charge Depleting) driving, in which the vehicle drives while consuming the state of charge SOC. Figures 11 and 13 are drive mode switching maps used in CS (Charge Sustain) driving, in which the vehicle drives to maintain the state of charge SOC.

[0066] 10 and 12 are used, for example, in a PHEV or the like equipped with a battery 64 of a relatively large capacity, when a CD mode is set for CD running, i.e., running while consuming the charged amount. In an HEV or the like equipped with a battery 64 of a smaller capacity than a PHEV, FIGS. 10 and 12 may not be used. FIGS. 11 and 13 are used, for example, in a PHEV or the like, when a CS mode is set for CS running, i.e., running while maintaining the charged amount. Alternatively, FIGS. 11 and 13 are used, for example, in an HEV or the like.

[0067] When the CD mode is set and the SOC is sufficient, FIG. 10 or FIG. 12 is selected, and Mode 1 is set across the entire range. When the CD mode is set but the SOC is low, or when the CS mode is set, FIG. 11 or FIG. 13 is selected. In FIG. 11 or FIG. 13, Mode 2 is set in the low-speed, low-load range where muffled noise is likely to be a problem. Mode 3 is set in the high-load range because it has high transmission efficiency in the high-load range. Mode 4 is set in the high-speed range because it has good transmission efficiency at the overdrive gear ratio, which is frequently used at high vehicle speeds. Even when the SOC is low and the usable range of the SOC is narrow, Mode 1 may be set in the range where the output of power from the battery 64 is small if consumption of the SOC is acceptable. Alternatively, Mode 1 may be set when the operating efficiency of the engine 20 is poor. In FIG. 11 or FIG. 13, Mode 1 is set in the low-speed, low-load range depending on the SOC.

[0068] 11 or 13, it can be seen that in the low vehicle speed / high load range, Mode 3 is set as the drive mode, and in the high vehicle speed range, Mode 4 is set as the drive mode. Or, looking at it from another perspective, it can be seen that in the high load range, Mode 3 is set as the drive mode, and in the high vehicle speed / low load range, Mode 4 is set as the drive mode.

[0069] However, when the vehicle 8 is traveling in Mode 2 in which the engine 20 is running to operate the first electric motor MG1 as a generator, and the third electric motor MG3 is operating as a prime mover using the generated power of the first electric motor MG1 (hereinafter referred to as series traveling), the pressing force between the pinion P and ring gear R of the differential mechanism 32 becomes smaller, and there is a risk that gear rattle noise will occur due to explosive vibrations of the engine 20.

[0070] Therefore, the electronic control device 70 of this embodiment performs control to generate an additional torque T2ad in the second electric motor MG2 when the vehicle 8 is running in series (hereinafter referred to as backlash reduction control), thereby reducing gear backlash and suppressing the occurrence of gear rattle noise. The additional torque T2ad corresponds to the "torque" and "torque generated in the second electric motor" in this invention.

[0071] FIG. 14 is a nomographic diagram illustrating the backlash elimination control performed by the electronic control device 70. FIG. 15 is a schematic diagram illustrating the operating state of the differential mechanism 32 during backlash elimination control, in which clockwise rotation around the first axis CS1 on the page is the direction in which the rotational speed is positive. FIG. 16 is a diagram illustrating engine shaft torque, which is the torque acting on the crankshaft (ring gear R) of the engine 20 during backlash elimination control. Note that in the following explanation, parts common to the above-mentioned FIG. 7(a) (mode 2 nomographic diagram) are assigned the same reference numerals and will not be described again. In addition, the offset torques (OT2ad1, OT2ad2) generated in the first rotating element RE1 by the mechanical transmission of the additional torque T2ad are indicated by outlined arrows.

[0072] When the vehicle 8 is running in series, the electronic control device 70 performs backlash-eliminating control by causing the second electric motor MG2 to generate an additional torque T2ad. Figures 14 to 16 show a case where the additional torque T2ad generates, of the offset torques (OT2ad1, OT2ad2) that are generated in the first rotating element RE1, an offset torque OT2ad1 that is a positive torque in the same direction as the engine torque Te during operation.

[0073] As shown in Figure 16, engine torque Te is expressed as the sum of a DC component Tedc, which indicates the average value of output over time, and an AC component Teac, which indicates the fluctuation of output over time caused by factors such as explosive vibrations of the engine 20. When the vehicle 8 is running in series, the engine torque Te and the first electric motor torque Tmg1 generated by the first electric motor MG1 are balanced, canceling out the DC component Tedc. The AC component Teac is located on the horizontal axis at 0 [N·m] and fluctuates between positive and negative values ​​across the 0 [N·m] value. In other words, torque fluctuations that vary between positive and negative values ​​occur in the ring gear R, which is the first rotating element RE1. This torque fluctuation causes rattle between the ring gear R and the pinion P, resulting in rattle noise.

[0074] The carrier C, which is the third rotating element RE3, is connected to the vehicle 8, which has a large inertia, and tends to maintain a constant rotational speed compared to the other rotating elements. Therefore, as shown in FIG. 15, the negative torque T2ad1 generated in the sun gear S by the second electric motor MG2 is transmitted to the ring gear R via the pinion P as an offset torque OT2ad1 (positive torque). The collinear diagram in FIG. 14 shows an operation in which the negative torque T2ad1 generated in the sun gear S is generated as an offset torque OT2ad1 (positive torque) in the ring gear R. As shown in FIG. 16, by generating the offset torque OT2ad1, the AC component Teac acting on the crankshaft (ring gear R) of the engine 20 is offset to the positive torque side, and the ring gear R is pressed in the acceleration direction (clockwise on the page in FIG. 15), thereby suppressing the occurrence of gear rattle noise. The offset torque OT2ad1 is determined in advance by design or experimentation to be a suitable value that can offset the lowest value of the AC component Teac toward the positive torque side and that can be as small as possible. Similarly, the negative torque T2ad1 is determined in advance by design or experimentation to be a suitable value that becomes the offset torque OT2ad1. The offset torque OT2ad1 corresponds to the "positive torque" in this invention.

[0075] By controlling the generation of the negative torque T2ad1, the second electric motor MG2 operates as a generator, and the electric power generated by the second electric motor MG2 is preferably used to power the third electric motor MG3 or to charge the battery 64, etc.

[0076] When the vehicle 8 is accelerating, the rotation speed of the third rotating element RE3 (carrier C) increases, and backlash is more easily eliminated when the AC component Teac is offset to the positive torque side. Therefore, the second electric motor MG2 generates negative torque T2ad1 to generate offset torque OT2ad1 (positive torque), thereby suitably eliminating backlash in the gears when the vehicle 8 is accelerating.

[0077] 17 to 19 are diagrams corresponding to the aforementioned Figs. 14 to 16, respectively, when the additional torque T2ad generates an offset torque OT2ad2, which is a negative torque opposite to the engine torque Te during operation, among the offset torques (OT2ad1, OT2ad2) generated in the first rotating element RE1. Fig. 17 is a collinear diagram, Fig. 18 is a schematic diagram explaining the operating state of the differential mechanism 32, and Fig. 19 is a diagram explaining the engine shaft torque, which is the torque acting on the crankshaft (ring gear R) of the engine 20.

[0078] The carrier C, which is the third rotating element RE3, is connected to the vehicle 8, which has a large inertia, and tends to maintain a constant rotational speed compared to the other rotating elements. Therefore, as shown in FIG. 18, the positive torque T2ad2 generated in the sun gear S by the second electric motor MG2 is transmitted to the ring gear R via the pinion P as an offset torque OT2ad2 (negative torque). The collinear diagram in FIG. 17 shows an operation in which the positive torque T2ad2 generated in the sun gear S is generated as an offset torque OT2ad2 (negative torque) in the ring gear R. By generating the offset torque OT2ad2 (negative torque), as shown in FIG. 19, the AC component Teac acting on the crankshaft (ring gear R) of the engine 20 is offset to the negative torque side, and the ring gear R is pressed in the deceleration direction (counterclockwise on the page of FIG. 18), thereby suppressing the occurrence of gear rattle noise. The offset torque OT2ad2 is determined in advance by design or experimentation to be a suitable value that can offset the highest value of the AC component Teac to the negative torque side and can be as small as possible. Similarly, the positive torque T2ad2 is determined in advance by design or experimentation to be a suitable value that becomes the offset torque OT2ad2. The offset torque OT2ad2 corresponds to the "negative torque" in this invention.

[0079] In the control of generating the positive torque T2ad2, the second electric motor MG2 operates as a prime mover, and the electric power consumed in the power running of the second electric motor MG2 is supplied by a portion of the electric power generated by the first electric motor MG1, while most of the electric power is supplied to the power running of the third electric motor MG3. Alternatively, when all of the electric power generated by the first electric motor MG1 is supplied to the power running of the third electric motor MG3, the electric power consumed in the power running of the second electric motor MG2 may be supplied by the electric power of the battery 64.

[0080] When the vehicle 8 is decelerating, the rotation speed of the third rotating element RE3 (carrier C) is decreasing, and it is easier to eliminate backlash if the AC component Teac is offset to the negative torque side. Therefore, the second electric motor MG2 generates positive torque T2ad2 to generate offset torque OT2ad2 (negative torque), thereby suitably eliminating backlash in the gears when the vehicle 8 is decelerating.

[0081] Fig. 20 is an example of a setting value map of the additional torque T2ad generated by the second electric motor MG2 in the backlash eliminating control performed by the electronic control device 70. In the backlash eliminating control, the offset torque (OT2ad1, OT2ad2) to be generated is switched depending on the acceleration or deceleration of the vehicle 8. That is, when the vehicle 8 is accelerating, the second electric motor MG2 generates a negative torque T2ad1 to generate the offset torque OT2ad1 (positive torque), and when the vehicle 8 is decelerating, the second electric motor MG2 generates a positive torque T2ad2 to generate the offset torque OT2ad2 (negative torque). Fig. 20 is a setting value map of the additional torque T2ad (negative torque T2ad1, positive torque T2ad2) for generating the offset torque (OT2ad1, OT2ad2). As the engine torque Te increases, the AC component Teac also increases. Therefore, the necessary offset torques (OT2ad1, OT2ad2) are increased in accordance with the increase in engine torque Te, and the set values ​​of the additional torques T2ad (negative torque T2ad1, positive torque T2ad2) are also increased accordingly. This allows gear backlash to be suitably eliminated regardless of the magnitude of the engine torque Te. In addition, the determination of acceleration / deceleration of the vehicle 8 is made, for example, by providing hysteresis to the determination value, so that the vehicle is determined to be either accelerating or decelerating even when traveling at a constant speed that is neither accelerating nor decelerating, and backlash elimination control is performed so that the additional torque T2ad does not become 0.

[0082] 21 is an example of a flowchart illustrating the control operation of the electronic control unit 70, and is a flowchart illustrating the control operation of the backlash elimination control performed by the electronic control unit 70. This flowchart is executed repeatedly, for example, while the vehicle is running.

[0083] First, in step (hereinafter, "step" will be omitted) S10, it is determined whether the vehicle 8 is in series running. If the determination in S10 is negative, in S20, the backlash elimination control, i.e., the generation of the additional torque T2ad by the second electric motor MG2, is stopped or not performed, and this routine is terminated.

[0084] If the determination in S10 is positive, then in S30 it is determined whether the vehicle 8 is accelerating. Whether or not the vehicle 8 is accelerating is determined, for example, based on whether the vehicle speed V has increased by a predetermined value or more within a predetermined period of time. If the determination in S30 is negative, that is, if the vehicle 8 is decelerating or traveling at a constant speed, then S40 is executed. In S40, a positive torque T2ad2 is generated by the second electric motor MG2, and an offset torque OT2ad2 (negative torque) is generated in the first rotating element RE1 (ring gear R), and this routine is then terminated.

[0085] If the determination in S30 is affirmative, S50 is executed. In S50, the second electric motor MG2 generates a negative torque T2ad1, and the first rotating element RE1 (ring gear R) generates an offset torque OT2ad1 (positive torque), and this routine is then terminated.

[0086] FIG. 22 is an example of a time chart when the backlash eliminating control performed by the electronic control device 70 involves control for generating an offset torque OT2ad1 (positive torque) by a negative torque T2ad1, that is, the control of S50 in FIG. 21.

[0087] First, at time t0, the accelerator is turned on (accelerator opening θacc is changed to θ1), a third electric motor torque Tmg3 (not shown) is output, and driving begins in Mode1_MG3 drive mode. Next, at time t1, the vehicle speed V reaches a target vehicle speed V1 for switching to Mode2 (series driving), so in order to switch to Mode2 (series driving), an engine starting torque Tg is generated by the first electric motor MG1, and motoring is started to rotate the crankshaft at the engine starting torque Tg in order to start the engine 20. As a result of motoring, a negative torque that resists motoring rotation is generated in the engine 20. Next, at time t2, the engine rotation speed Ne reaches a startable rotation speed Ne1, and fuel injection and ignition are performed. Furthermore, the engine starting torque Tg generated by the first electric motor MG1 is changed to a torque Tgs, and torque support is provided until the engine rotation speed Ne stabilizes. Then, at time t3 when the engine 20 has completed ignition and the engine rotation speed Ne has stabilized, the mode is switched to Mode 2 (series running), the second electric motor MG2 generates a negative torque T2ad1, and an offset torque OT2ad1 (positive torque) (not shown) is generated, thereby eliminating backlash in the gears and suppressing the occurrence of gear rattle noise.

[0088] As described above, according to this embodiment, the differential mechanism 32 has three rotating elements: the first rotating element RE1, the second rotating element RE2, and the third rotating element RE3. 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. The third electric motor MG3 is connected to the rear drive shaft 58. The electronic control device 70 is configured to generate an additional torque T2ad in the second electric motor MG2 when performing series running in which the engine 20 is operated to operate the first electric motor MG1 as a generator and the third electric motor MG3 is operated as a prime mover using the power generated by the first electric motor MG1. As a result, series running is possible in which the first electric motor MG1, which is connected to the same rotating element RE1 as the engine 20, is operated as a generator, and the generated electric power is used to operate the third electric motor MG3 as a prime mover to drive the rear drive shaft 58. This prevents torque vibrations of the engine 20 from being transmitted to the front drive shaft 38, making it less likely for the vehicle body to vibrate. Furthermore, when series running is performed, the pressing force between the gears of the differential mechanism 32 is reduced, which could cause gear rattle noise due to explosive vibrations of the engine 20. However, by generating additional torque T2ad in the second electric motor, the gear rattle can be eliminated, thereby suppressing the occurrence of gear rattle noise.

[0089] Furthermore, according to this embodiment, the electronic control device 70 is configured to cause the second electric motor MG2 to generate an offset torque OT2ad1 (positive torque) for the first rotating element RE1 during series running, thereby making it possible to suitably eliminate backlash in the gears when the vehicle 8 is accelerating.

[0090] Furthermore, according to this embodiment, the electronic control device 70 is configured to cause the second electric motor MG2 to generate an offset torque OT2ad2 (negative torque) for the first rotating element RE1 during series running, thereby making it possible to suitably eliminate backlash in the gears when the vehicle 8 is decelerating.

[0091] Furthermore, according to this embodiment, when performing series running, the electronic control device 70 is configured to cause the second electric motor MG2 to generate an offset torque OT2ad1 (positive torque) on the first rotating element RE1 when the vehicle 8 is accelerating, and to generate an offset torque OT2ad2 (negative torque) on the first rotating element RE1 when the vehicle 8 is decelerating. This makes it possible to suitably eliminate backlash in the gears regardless of whether the vehicle 8 is accelerating or decelerating.

[0092] Furthermore, according to this embodiment, the electronic control device 70 is configured to increase the additional torque T2ad generated by the second electric motor MG2 as the engine torque Te increases during series running, thereby enabling gear backlash to be suitably eliminated regardless of the magnitude of the engine torque Te.

[0093] 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]

[0094] 23 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. 23, 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.

[0095] 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 is in mesh 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.

[0096] FIG. 24 is a nomographic diagram illustrating the configuration of the vehicle drive device 310. In FIG. 24, 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 wheel 12f, is coupled to the third rotating element RE3. The brake BR is a brake mechanism 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 in the first embodiment described above, and therefore a description thereof will be omitted.

[0097] Similar to the vehicle driving device 10 of the first embodiment, the vehicle driving device 310 is capable of switching between a plurality of driving modes by controlling the engine 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 by the electronic control device 70. Furthermore, when switching between driving modes, the vehicle driving device 310 is controlled by the electronic control device 70 to engage the brake BR as necessary.

[0098] In the differential mechanism 332, 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 the mechanical point. That is, in the differential mechanism 332, the mechanical point is set by the speed-increasing ratio. Therefore, in the vehicle drive device 310, Mode 3 is the O / D input split mode, and Mode 4 is the O / D output split mode.

[0099] Fig. 25 is a nomographic diagram illustrating the backlash elimination control performed by the electronic control device 70 of this embodiment, and Fig. 26 is a schematic diagram illustrating the operating state of the differential mechanism 332 during the backlash elimination control. Fig. 25 corresponds to Fig. 14 of the first embodiment, and Fig. 26 corresponds to Fig. 15 of the first embodiment.

[0100] 25 and 26 show a case where an offset torque OT2ad1 (positive torque) is generated in the first rotating element RE1 (carrier C) by the additional torque T2ad. In this embodiment, the combination of torque directions of the offset torques (OT2ad1, OT2ad2) generated by the additional torque T2ad (negative torque T2ad1, positive torque T2ad2) is opposite to that in the first embodiment. That is, the offset torque OT2ad1 (positive torque) is generated by the generation of the positive torque T2ad2 by the second electric motor MG2, and the offset torque OT2ad2 (negative torque) is generated by the generation of the negative torque T2ad1 by the second electric motor MG2.

[0101] When the vehicle 300 is running in series, the engine torque Te and the first electric motor torque Tmg1 for generating electricity by the first electric motor MG1 are balanced, and as in the case of the above-described first embodiment, torque fluctuations across positive and negative values ​​occur in the carrier C, which is the first rotating element RE1, due to the AC component Teac. This torque fluctuation causes rattles between the sun gear S and the pinion P, and between the pinion P and the ring gear R, which causes rattle noise.

[0102] The ring gear R, which is the third rotating element RE3, is connected to the vehicle 300, which has a large inertia, and tends to maintain a constant rotational speed compared to the other rotating elements. Therefore, the positive torque T2ad2 generated in the sun gear S by the second electric motor MG2 is transmitted to the carrier C via the pinion P as an offset torque OT2ad1 (positive torque) (see FIGS. 25 and 26). By generating the offset torque OT2ad1 (positive torque), the AC component Teac acting on the crankshaft (carrier C) of the engine 20 is offset to the positive torque side, as in the case of the above-described first embodiment (FIG. 16), and the carrier C is pressed in the acceleration direction (clockwise on the page of FIG. 26), thereby suppressing the occurrence of gear rattle noise.

[0103] Furthermore, when the second electric motor MG2 generates negative torque T2ad1 and offset torque OT2ad2 (negative torque), the AC component Teac acting on the crankshaft (carrier C) of the engine 20 is offset to the negative torque side, as in the case of the above-described first embodiment (FIG. 19). The carrier C is pressed in the deceleration direction (counterclockwise on the page of FIG. 26), and the occurrence of gear rattle noise is suppressed.

[0104] When the vehicle 300 is accelerating, i.e., when the rotation speed of the third rotating element RE3 (ring gear R) is increasing, backlash is more easily eliminated if the AC component Teac is offset toward the positive torque side. On the other hand, when the vehicle 300 is decelerating, i.e., when the rotation speed of the third rotating element RE3 (ring gear R) is decreasing, backlash is more easily eliminated if the AC component Teac is offset toward the negative torque side. Therefore, the second electric motor MG2 generates positive torque T2ad2 to generate offset torque OT2ad1 (positive torque), which effectively eliminates gear backlash when the vehicle 300 is accelerating, and the second electric motor MG2 generates negative torque T2ad1 to generate offset torque OT2ad2 (negative torque), which effectively eliminates gear backlash when the vehicle 300 is decelerating.

[0105] Fig. 27 is an example of a map showing a set value of the additional torque T2ad generated by the second electric motor MG2 in the backlash-eliminating control performed by the electronic control unit 70. This map is used to perform control similar to that of the first embodiment (control shown by the map in Fig. 20), in which the offset torque (OT2ad1, OT2ad2) generated is switched depending on the acceleration / deceleration of the vehicle and the additional torque T2ad is increased depending on the magnitude of the engine torque Te. In this embodiment, the combination of the torque directions of the offset torques (OT2ad1, OT2ad2) generated by the additional torque T2ad (negative torque T2ad1, positive torque T2ad2) is opposite to that of the first embodiment, and therefore Fig. 27 is a map in which the positive and negative directions are reversed during vehicle acceleration and deceleration, as compared to Fig. 20 of the first embodiment.

[0106] Furthermore, by reversing the combination of torque directions of the offset torques (OT2ad1, OT2ad2) generated by the additional torque T2ad (negative torque T2ad1, positive torque T2ad2) from that of the first embodiment, the flowchart shown in FIG. 21 and the time chart shown in FIG. 22 of the first embodiment can be implemented in the same way in this embodiment.

[0107] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained. [Example]

[0108] 28 is a diagram illustrating a schematic configuration of a vehicle 400 equipped with a vehicle drive device 410 (including a front drive unit 410f and a rear drive unit 410r) to which the present invention is applied. In FIG. 28, 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.

[0109] 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.

[0110] FIG. 29 is a nomographic diagram illustrating the configuration of the vehicle drive device 410. In FIG. 29, 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 wheel 12f, is coupled to the third rotating element RE3. The brake BR is a brake mechanism that stops rotation of the first rotating element RE1 when engaged. The rear drive unit 410r is the same as the rear drive unit 10r in the first embodiment described above, and therefore a description thereof will be omitted.

[0111] Similar to the vehicle driving device 10 of the first embodiment, the vehicle driving device 410 is capable of switching between a plurality of driving modes by controlling the engine 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 by the electronic control device 70. Furthermore, when switching between driving modes, the vehicle driving device 410 is controlled by the electronic control device 70 to engage the brake BR as necessary.

[0112] In differential mechanism 432, 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 432, the mechanical point is set by the reduction ratio. Therefore, in vehicle drive device 410, Mode 3 is U / D input split mode, and Mode 4 is U / D output split mode.

[0113] Fig. 30 is a nomographic diagram illustrating the backlash elimination control performed by the electronic control device 70 of this embodiment, and Fig. 31 is a schematic diagram illustrating the operating state of the differential mechanism 432 during backlash elimination control. Fig. 30 and Fig. 31 show a case where an offset torque OT2ad1 (positive torque) is generated in the first rotating element RE1 (carrier C) by the additional torque T2ad, with Fig. 30 corresponding to Fig. 14 of the first embodiment and Fig. 31 corresponding to Fig. 15 of the first embodiment.

[0114] When the vehicle 400 is running in series, the engine torque Te and the first electric motor torque Tmg1 for generating electricity by the first electric motor MG1 are balanced, and as in the case of the above-described first embodiment, torque fluctuations across positive and negative values ​​are generated in the carrier C, which is the first rotating element RE1, due to the AC component Teac. This torque fluctuation generates rattles between the sun gear S and the pinion Pa, and between the pinion Pb and the ring gear R, which causes rattle noise.

[0115] As shown in Figures 30 and 31, in this embodiment, compared to the first embodiment, the first rotating element RE1 changes from the ring gear R to the carrier C, and the third rotating element RE3 changes from the carrier C to the ring gear R. However, similar to the first embodiment, the negative torque T2ad1 generated in the second electric motor MG2 generates an offset torque OT2ad1 (positive torque) in the first rotating element RE1. Similarly, the positive torque T2ad2 generated in the second electric motor MG2 generates an offset torque OT2ad2 (negative torque) in the first rotating element RE1. That is, in the backlash elimination control of this embodiment, the first rotating element RE1 is set as the carrier C and the third rotating element RE3 is set as the ring gear R, and thus the same control operation as in the first embodiment is performed.

[0116] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained. [Example]

[0117] Fig. 32 is a diagram illustrating a schematic configuration of a vehicle 500 equipped with a vehicle drive device 510 (including a front drive unit 510f and a rear drive unit 510r) to which the present invention is applied. In Fig. 32, 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.

[0118] 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. An 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 is in mesh 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.

[0119] FIG. 33 is a diagram illustrating the configuration of a vehicle drive device 510 using a collinear diagram. In FIG. 33, a differential mechanism 532 of a 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 collinear diagram, the first rotating element RE1 is a ring gear R. The engine 20 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 38, i.e., the front wheels 12f, are coupled to the third rotating element RE3. The brake BR is a brake mechanism that stops rotation of the first rotating element RE1 when engaged. The rear drive unit 510r is the same as the rear drive unit 10r in the first embodiment described above, and therefore a description thereof will be omitted.

[0120] Similar to the vehicle driving device 10 of the first embodiment, the vehicle driving device 510 is capable of switching between a plurality of driving modes by controlling the engine 20, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 by the electronic control device 70. Furthermore, when switching between driving modes, the vehicle driving device 510 is controlled by the electronic control device 70 to engage the brake BR as necessary.

[0121] In differential mechanism 532, the rotational speed of third rotating element RE3, which is the output element, is on the speed-increasing side, or overdrive (O / D) side, relative to engine rotational speed Ne at a mechanical point. That is, in differential mechanism 532, the mechanical point is set by a speed-increasing ratio. Therefore, in vehicle drive device 510, Mode 3 is an O / D input split mode, and Mode 4 is an O / D output split mode.

[0122] Fig. 34 is a nomographic diagram illustrating the backlash elimination control performed by the electronic control device 70 of this embodiment, and Fig. 35 is a schematic diagram illustrating the operating state of the differential mechanism 532 during backlash elimination control. Fig. 34 and Fig. 35 show a case where an offset torque OT2ad1 (positive torque) is generated in the first rotating element RE1 (ring gear R) by the additional torque T2ad, with Fig. 34 corresponding to Fig. 25 of the second embodiment described above, and Fig. 35 corresponding to Fig. 26 of the second embodiment.

[0123] When the vehicle 500 is running in series running, the engine torque Te and the first electric motor torque Tmg1 for generating electricity by the first electric motor MG1 are balanced, and as in the case of the above-described first embodiment, torque fluctuations across positive and negative values ​​are generated in the ring gear R, which is the first rotating element RE1, due to the AC component Teac. This torque fluctuation generates rattle between the pinion Pb and the ring gear R, which causes rattle noise.

[0124] As shown in Figures 34 and 35, in this embodiment, compared to the second embodiment, the first rotating element RE1 changes from a carrier C to a ring gear R, and the third rotating element RE3 changes from a ring gear to a carrier C. However, as in the second embodiment, an offset torque OT2ad1 (positive torque) is generated in the first rotating element RE1 due to the positive torque T2ad2 generated in the second electric motor MG2. Similarly, an offset torque OT2ad2 (negative torque) is generated in the first rotating element RE1 due to the negative torque T2ad1 generated in the second electric motor MG2. That is, in the backlash elimination control of this embodiment, the first rotating element RE1 is set to the ring gear R and the third rotating element RE3 is set to the carrier C, and thus a control operation similar to that in the second embodiment is performed.

[0125] As described above, according to this embodiment, the same effects as those of the second embodiment, ie, the first embodiment, can be obtained.

[0126] 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.

[0127] For example, in the differential mechanism 32 of the first 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 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.

[0128] In the differential mechanism 332 of the second 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.

[0129] In the differential mechanism 432 of the third 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.

[0130] In the differential mechanism 532 of the fourth 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.

[0131] Here, as shown in the above-mentioned Examples 1-4, 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.

[0132] In the above-described Examples 1-4, 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.

[0133] In addition, in the above-described Examples 1 to 4, the first electric motor MG1 may be disposed 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 disposed on the first axis CS1, which is the rotational axis of the differential mechanism 32.

[0134] In addition, in the above-described embodiments 1-4, a one-way clutch may be used as the brake mechanism for stopping the rotation of the first rotating element RE1 instead of the brake BR.

[0135] In addition, in the above-described Examples 1 to 4, the brake BR does not necessarily have to be provided. In this case, Mode1_MG2_BRon in 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.

[0136] In addition, in the above-described Examples 1 to 4, 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.

[0137] Furthermore, in the above-mentioned Examples 1-4, 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 20 or the second electric motor MG2 may be used as the main engine.

[0138] 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]

[0139] 8: Vehicle 10: Vehicle drive unit 12f: Front wheels (first drive wheels) 12r: Rear wheels (second drive wheels) 20: Engine 32: Differential mechanism S: Sun gear (second rotating element) C: Carrier (third rotating element) R: Ring gear (first rotating element) 38: Front drive shaft (first drive shaft) 58: Rear drive shaft (second drive shaft) 70: Electronic control unit (control unit) 300: Vehicle 310: Vehicle drive unit 332: Differential mechanism S: Sun gear (second rotating element) C: Carrier (first rotating element) R: Ring gear (third rotating element) 400: Vehicle 410: Vehicle drive unit 432: Differential mechanism S: Sun gear (second rotating element) C: Carrier (first rotating element) R: Ring gear (third rotating element) 500: Vehicle 510: Vehicle drive unit 532: Differential mechanism S: Sun gear (second rotating element) C: Carrier (third rotating element) R: Ring gear (first rotating element) MG1: First electric motor MG2: Second electric motor MG3: Third electric motor Te: Engine torque (engine torque) OT2ad1: Offset torque (positive torque generated in the first rotating element) OT2ad2: Offset torque (negative torque generated in the first rotating element) T2ad: Additional torque (torque generated in the second electric motor) T2ad1: Negative torque T2ad2: Positive torque Tmg1: First electric motor torque (torque of the first electric motor) RE1: First rotating element RE2: Second rotating element RE3: Third rotating element

Claims

1. 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 front wheels and rear wheels, a second drive shaft that drives the other of the front wheels and the rear wheels, and a control device, the differential mechanism has three rotation elements: a first rotation element, a second rotation element, and a third rotation element; 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, The third electric motor is connected to the second drive shaft, The control device is configured to cause the second electric motor to generate torque when performing series running in which the engine is operated to operate the first electric motor as a generator and the third electric motor is operated as a prime mover using the generated power of the first electric motor. A vehicle drive device characterized by:

2. The control device is configured to, when the series running is performed, cause the first rotating element to generate a positive torque in the second electric motor in the same direction as the torque of the engine during operation.

2. The vehicle drive system according to claim 1.

3. The control device is configured to, when the series running is performed, cause the first rotating element to generate a negative torque in the second electric motor in a direction opposite to the torque of the engine during operation.

2. The vehicle drive system according to claim 1.

4. The control device is configured to, when the series running is performed, cause the second electric motor to generate, on the first rotating element, a positive torque in the same direction as the torque of the engine when the vehicle is operating when the vehicle is accelerating, and cause the first rotating element to generate, on the second electric motor, a negative torque in the opposite direction to the torque of the engine when the vehicle is operating when the vehicle is decelerating.

2. The vehicle drive system according to claim 1.

5. The control device is configured to increase the torque generated by the second electric motor as the torque of the engine increases during series running.

5. The vehicle drive device according to claim 1, wherein the first and second power supplies are connected to the first and second power supplies.

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