Vehicle drive systems

Abstract

In a planetary gear system which is a differential mechanism, the radial dimensions of the drive unit, to which the engine, first electric motor, second electric motor, and drive shaft are connected, can be reduced relative to the first to third rotating elements. [Solution] (a) The first planetary gear set 40 functions as a differential mechanism, (b) The second planetary gear set 44 functions as a reduction mechanism, (c) In the first planetary gear set 40, the first rotating element RE1 is connected to the engine 12 and the first electric motor MG1, the second rotating element RE2 is connected to the second electric motor MG2, and the third rotating element RE3 is connected to the first drive shaft 28, (d) The first electric motor MG1, the second electric motor MG2, the first planetary gear set 40, and the second planetary gear set 44 are arranged on the same first axis C1, and (e) The first electric motor MG1 and the second planetary gear set 44 are both located on the engine 12 side when viewed from the second electric motor MG2 and the first planetary gear set 40.

Description

Technical Field

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[0001] The present invention relates to a vehicle drive device including an engine, a drive unit including a first electric motor, a second electric motor, a first planetary gear device and a second planetary gear device each having three rotating elements, and a drive shaft for driving one of a front wheel and a rear wheel.

Background Art

[0002] There is known a vehicle drive device including an engine, a drive unit including an electric motor MG1, an electric motor MG2, and a plurality of planetary gear devices each having three rotating elements, and a drive shaft for driving one of a front wheel and a rear wheel. For example, the vehicle drive device described in Patent Document 1 is such a device. In the drive unit described in FIG. 14 of Patent Document 1, the electric motor MG1, the electric motor MG2, the planetary gear device 10, the planetary gear device 20, and the planetary gear device 40 are arranged coaxially. Thereby, the radial dimension of the drive unit, that is, the dimension around the body can be reduced.

Prior Art Documents

Patent Documents

[0003] [[ID=​​​​​​​​​​​​​​​The present invention was made against the above circumstances, and its objective is to provide a vehicle drive system that can reduce the radial dimensions of a drive unit in which an engine is connected to the first rotating element of a planetary gear system that functions as a differential mechanism, a first electric motor is connected to the first rotating element via a planetary gear system that functions as a reduction mechanism, a second electric motor is connected to the second rotating element, and a drive shaft is connected to the third rotating element. [Means for solving the problem]

[0006] The gist of the first invention is a vehicle drive system comprising an engine, a first drive unit including a first electric motor, a second electric motor, a first planetary gear system and a second planetary gear system each having three rotating elements, and a first drive shaft that drives either the front wheel or the rear wheel, wherein (a) the first planetary gear system has three rotating elements, a first rotating element, a second rotating element and a third rotating element, and functions as a differential mechanism, and (b) the second planetary gear system is configured to transmit power to the first electric motor to the first planetary gear system while reducing its rotational speed to be slower than that of the first electric motor. The reduction mechanism functions such that (c) the engine is connected to the first rotating element and the first electric motor is connected via the second planetary gear set, 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 first electric motor, the second electric motor, the first planetary gear set, and the second planetary gear set are arranged on the same first axis which is the axis of rotation, and (e) the first electric motor and the second planetary gear set are both located on the engine side when viewed from the second electric motor and the first planetary gear set.

[0007] The gist of the second invention is that, in the first invention, (a) the first planetary gear device is a double pinion type having a first sun gear, a first carrier, and a first ring gear, and (b) the first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear.

[0008] The gist of the third invention is that, in the first invention, (a) the first planetary gear device is a single-pinion type having a first sun gear, a first carrier, and a first ring gear, and (b) the first rotating element is the first ring gear, the second rotating element is the first sun gear, and the third rotating element is the first carrier.

[0009] The gist of the fourth invention is that, in the first invention, (a) the first planetary gear device is a double pinion type having a first sun gear, a first carrier, and a first ring gear, and (b) the first rotating element is the first ring gear, the second rotating element is the first sun gear, and the third rotating element is the first carrier.

[0010] The gist of the fifth invention is that, in the first invention, (a) the first planetary gear device is a single-pinion type having a first sun gear, a first carrier, and a first ring gear, and (b) the first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear.

[0011] The gist of the sixth invention is that, in any one of the first to fifth inventions, (a) the second planetary gear device is a single-pinion type having a second sun gear, a second carrier, and a second ring gear, and (b) one of the second sun gear and the second ring gear is fixed to a non-rotating member, the other of the second sun gear and the second ring gear is connected to the first electric motor, and the second carrier is connected to the first rotating element.

[0012] The gist of the seventh invention is that, in any one of the first to fifth inventions, (a) the second planetary gear device is a double pinion type having a second sun gear, a second carrier, and a second ring gear, and (b) one of the second sun gear and the second carrier is fixed to a non-rotating member, the other of the second sun gear and the second carrier is connected to the first electric motor, and the second ring gear is connected to the first rotating element.

[0013] The gist of the eighth invention is that, in any one of the first to seventh inventions, the first planetary gear set and the second planetary gear set are arranged adjacent to each other between the first motor and the second motor.

[0014] The gist of the ninth invention is that, in the eighth invention which references the first invention, (a) the first planetary gear device is a double pinion type having a first sun gear, a first pinion, a first carrier and a first ring gear, (b) the first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear, (c) the first pinion is supported by the first carrier from the engine side, (d) the second planetary gear device is a single pinion type having a second sun gear, a second pinion, a second carrier and a second ring gear, (e) the second ring gear is fixed to a non-rotating member, the second sun gear is connected to the first electric motor, the second carrier is connected to the first carrier, and (f) the second pinion is supported by the second carrier from the side opposite to the engine.

[0015] The gist of the tenth invention is that, in the first invention, (a) the second electric motor is located on the opposite side from the engine when viewed from the first planetary gear set, and (b) the first drive shaft is connected to the third rotating element without passing through the inside of the connecting shaft that connects the second electric motor and the second rotating element, via an output shaft having a second axis different from the first axis as its axis of rotation, and a power transmission mechanism that transmits power between the output shaft and the third rotating element.

[0016] The gist of the 11th invention is that, in the 10th invention, (a) the first drive shaft is a drive shaft that drives the front wheel, and (b) the output shaft extends from the power transmission mechanism to the engine side and is connected to the first drive shaft.

[0017] The gist of the twelfth invention is that, in any one of the first to eleventh inventions, a second drive shaft is further provided for driving the other of the front wheel and the rear wheel, and a second drive unit is further provided, which includes a third electric motor connected to the second drive shaft. [Effects of the Invention]

[0018] According to the vehicle drive system of the first invention, (a) the first planetary gear system has three rotating elements, a first rotating element, a second rotating element, and a third rotating element, and functions as a differential mechanism; (b) the second planetary gear system functions as a reduction mechanism that connects the first electric motor to the first planetary gear system so as to transmit power while reducing its rotational speed to that of the first electric motor; (c) the engine is connected to the first rotating element and the first electric motor is connected via the second planetary gear system, 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 first electric motor, the second electric motor, the first planetary gear system, and the second planetary gear system are arranged on a first axis which is the same axis of rotation; and (e) the first electric motor and the second planetary gear system are both located on the engine side as seen from the second electric motor and the first planetary gear system. For example, since the first electric motor is connected to the second planetary gear unit, the first electric motor and the second planetary gear unit are arranged adjacent to each other in the first axial direction. For example, since the second electric motor is connected to the second rotating element of the first planetary gear unit, the second electric motor and the first planetary gear unit are arranged adjacent to each other in the first axial direction. In the first axial direction, if both the first electric motor and the second planetary gear unit are located on the opposite side of the engine from the second electric motor and the first planetary gear unit, the engine and the second planetary gear unit are connected by passing through the position where the second electric motor and the first planetary gear unit are located. That is, in the first axial direction, the rotating shaft connecting the engine and the second planetary gear unit must be located at the same position as the rotating shaft connecting the second electric motor and the first planetary gear unit. For example, the rotating shaft connecting the engine and the second planetary gear unit is inserted through the inside of the rotating shaft connecting the second electric motor and the first planetary gear unit. The rotating shaft connecting the first planetary gear system and the first drive shaft must be positioned to avoid all of the following: the rotating shaft connecting the engine and the second planetary gear system, the rotating shaft connecting the second electric motor and the first planetary gear system, and the rotating shaft connecting the first electric motor and the second planetary gear system, which is located on the opposite side of the engine from the first planetary gear system in the first axial direction.On the other hand, in the first axial direction, if both the first electric motor and the second planetary gear system are located on the engine side when viewed from the second electric motor and the first planetary gear system, then neither the first electric motor nor the second planetary gear system is located on the opposite side of the first planetary gear system from the engine. Therefore, the rotating shaft connecting the first planetary gear system and the first drive shaft only needs to be positioned to avoid both the rotating shaft connecting the engine and the second planetary gear system, and the rotating shaft connecting the second electric motor and the first planetary gear system. In this way, when the first electric motor and the second planetary gear system are located on the engine side when viewed from the second electric motor and the first planetary gear system in the first axial direction, the constraints on positioning the rotating shaft connecting the first planetary gear system and the first drive shaft are relaxed compared to the case where they are not, making it easier to reduce the radial dimensions of the first drive unit. Reducing the radial dimensions of the first drive unit improves, for example, the mountability of the first drive unit on a vehicle.

[0019] According to the vehicle drive device of the second invention, in the first invention, (a) the first planetary gear device is a double pinion type having a first sun gear, a first carrier and a first ring gear, and (b) the first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear. With this connection configuration of the first planetary gear device which is a double pinion type, the mechanical point at which the rotational speed of the second electric motor is set to zero can be set by the reduction ratio.

[0020] According to the vehicle drive device of the third invention, in the first invention, (a) the first planetary gear device is a single-pinion type having a first sun gear, a first carrier, and a first ring gear, and (b) the first rotating element is the first ring gear, the second rotating element is the first sun gear, and the third rotating element is the first carrier. With this connection configuration of the first planetary gear device, which is a single-pinion type, the mechanical point at which the rotational speed of the second electric motor is set to zero can be set by the speed increase ratio.

[0021] According to the vehicle drive device of the fourth invention, in the first invention, (a) the first planetary gear device is a double pinion type having a first sun gear, a first carrier and a first ring gear, and (b) the first rotating element is the first ring gear, the second rotating element is the first sun gear, and the third rotating element is the first carrier. With this connection configuration of the first planetary gear device which is a double pinion type, the mechanical point at which the rotational speed of the second electric motor is set to zero can be set by the speed increase ratio.

[0022] According to the vehicle drive device of the fifth invention, in the first invention, (a) the first planetary gear device is a single-pinion type having a first sun gear, a first carrier, and a first ring gear, and (b) the first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear. With this connection configuration of the first planetary gear device, which is a single-pinion type, the mechanical point at which the rotational speed of the second electric motor is set to zero can be set by the speed increase ratio.

[0023] According to the vehicle drive device of the sixth invention, in any one of the first to third inventions, (a) the second planetary gear device is a single-pinion type having a second sun gear, a second carrier, and a second ring gear, and (b) one of the second sun gear and the second ring gear is fixed to a non-rotating member, the other of the second sun gear and the second ring gear is connected to the first electric motor, and the second carrier is connected to the first rotating element. With this single-pinion type connection configuration of the second planetary gear device, the second planetary gear device can be connected to the first planetary gear device so as to transmit power to the first electric motor at a speed lower than the rotational speed of the first electric motor.

[0024] According to the drive device for a vehicle of the seventh invention, in any one of the first to fifth inventions, (a) the second planetary gear device is a double pinion type having a second sun gear, a second carrier, and a second ring gear, and (b) one of the second sun gear and the second carrier is fixed to a non-rotating member, the other of the second sun gear and the second carrier is connected to the first electric motor, and the second ring gear is connected to the first rotating element. With such a connection configuration of the double pinion type second planetary gear device, the second planetary gear device can connect the first electric motor to the first planetary gear device in a power transmissible manner while reducing the rotational speed of the first electric motor.

[0025] According to the drive device for a vehicle of the eighth invention, in any one of the first to seventh inventions, the first planetary gear device and the second planetary gear device are arranged adjacent to each other between the first electric motor and the second electric motor. Thereby, integration of the first planetary gear device and the second planetary gear device can be achieved, and miniaturization of the first drive unit can be achieved in the axial direction of the first drive unit.

[0026] According to the vehicle drive device of the ninth invention, in the eighth invention citing the first invention, (a) the first planetary gear device is a double pinion type having a first sun gear, a first pinion, a first carrier, and a first ring gear; (b) the first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear; (c) the first pinion is supported by the first carrier from the engine side; (d) the second planetary gear device is a single pinion type having a second sun gear, a second pinion, a second carrier, and a second ring gear; (e) the second ring gear is fixed to a non-rotating member, the second sun gear is connected to the first electric motor, and the second carrier is connected to the first carrier; (f) the second pinion is supported by the second carrier from the side opposite to the engine. With such a configuration, the first carrier of the first planetary gear device and the second carrier of the second planetary gear device can be arranged adjacent to each other in the first axial direction. Also, since the first pinion of the first planetary gear device is supported by the first carrier from the engine side and the second pinion of the second planetary gear device is supported by the second carrier from the side opposite to the engine, the first pinion and the second pinion can be made common. As a result, further miniaturization of the first drive unit can be achieved.

[0027] According to the vehicle drive device of the tenth invention, in the first invention, (a) the second electric motor is arranged on the side opposite to the engine when viewed from the first planetary gear device; (b) the first drive shaft is connected to the third rotating element through an output shaft having a second axis different from the first axis as a rotation axis and a power transmission mechanism that transmits power between the output shaft and the third rotating element, without passing through the inside of a connecting shaft that connects the second electric motor and the second rotating element. Thus, an output shaft is provided to connect the first drive shaft and the third rotating element. When compared with the case where the output shaft passes through the inside of the connecting shaft that connects the second electric motor and the second rotating element, when the output shaft does not pass through the inside of the connecting shaft, it is easier to suppress an increase in the radial size of the second electric motor.

[0028] According to the vehicle drive system of the 11th invention, in the 10th invention, (a) the first drive shaft is a drive shaft that drives the front wheels, and (b) the output shaft extends from the power transmission mechanism toward the engine and is connected to the first drive shaft. When the output shaft extends from the power transmission mechanism toward the engine and is connected to the first drive shaft, the extension of the output shaft toward the opposite side of the engine from the power transmission mechanism can be reduced compared to the case where it is not. This makes it easier to secure space for, for example, a battery that exchanges power with the first and second electric motors.

[0029] According to the vehicle drive system of the 12th invention, in any one of the first to 11th inventions, a second drive shaft is further provided for driving the other of the front wheel and the rear wheel, and a second drive unit is further provided, which includes a third electric motor connected to the second drive shaft. With this configuration, for example, the vehicle's drive modes can include so-called series driving. Compared to the case where the second drive unit is not provided, a variety of drive modes can be realized when the second drive unit is provided. [Brief explanation of the drawing]

[0030] [Figure 1] This diagram illustrates the schematic configuration of a vehicle equipped with a vehicle drive system according to Example 1. [Figure 2] This diagram shows the configuration of a vehicle's drive system using a collinear diagram. [Figure 3] This is a collinear diagram illustrating the BEV mode, which generates torque for the first and second electric motors. [Figure 4] This is a collinear diagram illustrating the BEV mode, in which torque is generated in the second motor while the brakes are engaged. [Figure 5] This is a collinear diagram illustrating the BEV mode, in which torque is generated in the third motor while the brakes are engaged. [Figure 6]This is a collinear diagram illustrating the first HEV mode (series mode), in which the engine is driven to rotate and power is exchanged between the first and third electric motors. (a) is a collinear diagram when torque is generated in the third electric motor by the power generated by the first electric motor. (b) is a collinear diagram when the power generated by the third electric motor is consumed by the first electric motor's traction to apply engine braking. [Figure 7] This is a collinear diagram illustrating the second HEV mode (input split mode), in which the engine is running and power is exchanged between the second and third motors. (a) is a collinear diagram when torque is generated in the third motor by the power generated by the second motor. (b) is a collinear diagram when torque is generated in the second motor by the power generated by the third motor. [Figure 8] This is a collinear diagram illustrating the third HEV mode (output split mode) in which the engine is running and power is exchanged between the first and second motors. (a) is a collinear diagram when torque is generated in the second motor by the power generated by the first motor. (b) is a collinear diagram when torque is generated in the first motor by the power generated by the second motor. [Figure 9] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 2. [Figure 10] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 3. [Figure 11] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 4. [Figure 12] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 5. [Figure 13] This is a collinear diagram illustrating the second HEV mode in Example 5, in which the engine is operated and power is exchanged between the second and third electric motors. [Figure 14] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 6. [Figure 15] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 7. [Figure 16]This is a collinear diagram illustrating the second HEV mode in Example 7, in which the engine is operated and power is exchanged between the second and third electric motors. [Figure 17] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 8. [Figure 18] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 9. [Figure 19] This is a collinear diagram illustrating the second HEV mode in Example 9, in which the engine is operated and power is exchanged between the second and third electric motors. [Figure 20] This diagram illustrates the schematic configuration of a vehicle drive system according to Example 10. [Modes for carrying out the invention]

[0031] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. Unless otherwise specified, the drawings in each embodiment have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily accurately depicted. Furthermore, in each embodiment, if the configuration is substantially the same as that of a prior embodiment, the explanation will focus on the differences, and parts that are substantially common in function with those of the prior embodiment will be given the same reference numerals and their explanation will be omitted as appropriate. In each embodiment, if the configuration is substantially the same as that of a prior embodiment, unless otherwise specified, the drive mode can be switched to any of the multiple modes, similar to the prior embodiment.

[0032] Hereinafter, the radial direction centered on the first axis C1 will simply be referred to as the "radial direction." The "radial direction" refers to the radial direction in the front drive units 20, 120, 220, 320, 420, 520, 620, 720, 820, and 920 in each of the embodiments described later. [Examples]

[0033] Figure 1 is a diagram illustrating the schematic configuration of a vehicle 90 equipped with a vehicle drive unit 10 according to Embodiment 1.

[0034] Vehicle 90 is a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV). Furthermore, vehicle 90 is an all-wheel-drive vehicle capable of independently driving the left and right front wheels 14f and the left and right rear wheels 14r. All-wheel drive (AWD) and four-wheel drive (4WD) are synonymous. Note that "left and right" above refers to the left and right sides of vehicle 90 in the forward direction. Hereafter, "left and right front wheels 14f" and "left and right rear wheels 14r" will be simply referred to as "front wheels 14f" and "rear wheels 14r," respectively.

[0035] The vehicle 90 comprises an engine 12, wheels 14 including front wheels 14f and rear wheels 14r, a first power transmission path between the engine 12 and the front wheels 14f, and a second power transmission path between the engine 12 and the rear wheels 14r. The vehicle 90 also includes an inverter 70, a battery 72, and an electronic control unit 80.

[0036] The engine 12 is a power source for driving and is a well-known internal combustion engine. The engine torque Te [N·m], which is the output torque of the engine 12, is controlled by the electronic control unit 80. In this specification, unless otherwise specified, torque, driving force, power, and force (=power) are synonymous. In two-wheel drive driving (=2WD driving), either the front wheels 14f or the rear wheels 14r are the drive wheels. In four-wheel drive driving (=4WD driving), both the front wheels 14f and the rear wheels 14r are the drive wheels.

[0037] The first power transmission path includes, in order from the engine 12 side, a front drive unit 20, a transfer case 22, a front propeller shaft 24, a front differential gear 26, and left and right front drive shafts 28, as shown in Figure 1. Hereinafter, the left and right front drive shafts 28 will be simply referred to as "front drive shafts 28". The transfer case 22, front propeller shaft 24, front differential gear 26, and front drive shafts 28 are well-known configurations. The transfer case 22 is a front and rear wheel power distribution device capable of distributing the input power to the front wheels 14f and rear wheels 14r. The front drive unit 20 is a unit that drives at least the front wheel 14f of the front wheels 14f and rear wheels 14r, and corresponds to the "first drive unit" in the present invention. The front drive shaft 28 corresponds to the "first drive shaft" in the present invention.

[0038] The front drive unit 20 includes a first motor MG1, a second motor MG2, and a first planetary gear set 40 and a second planetary gear set 44, each having three rotating elements. The first motor MG1 and the second motor MG2 are rotating electric machines, so-called motor generators, that have functions as prime movers and generators, respectively, and are, for example, three-phase synchronous motors. The configuration of the front drive unit 20 will be described later.

[0039] As shown in Figure 1, the second power transmission path includes, in order from the engine 12 side, a front drive unit 20, a transfer case 22, a rear propeller shaft 30 that transmits power distributed by the transfer case 22 to the rear wheels 14r in the front-to-rear wheel distribution mode described later, an electronically controlled coupling device 32, a transmission shaft 34, a rear differential gear 36, and left and right rear drive shafts 38. A third electric motor MG3 is connected to the transmission shaft 34. The third electric motor MG3 is a rotating electric machine, a so-called motor generator, that has the functions of both a prime mover and a generator, and is, for example, a three-phase synchronous motor. Hereinafter, the left and right rear drive shafts 38 will be simply referred to as "rear drive shafts 38". The rear propeller shaft 30, electronically controlled coupling device 32, transmission shaft 34, rear differential gear 36, and rear drive shafts 38 have a well-known configuration. The electronically controlled coupling device 32 can adjust the torque transmitted from the transfer case 22 to the rear differential gear 36 by controlling its transmission torque capacity (also called the fastening torque). The transmission shaft 34 and the third electric motor MG3 constitute the rear drive unit 60. The configuration of the rear drive unit 60 will be described later. The rear drive unit 60 is a unit that drives the rear wheel 14r of the front wheel 14f and rear wheel 14r, and corresponds to the "second drive unit" in this invention. The rear drive shaft 38 corresponds to the "second drive shaft" in this invention.

[0040] The inverter 70 is a well-known power supply circuit that converts DC to AC and AC to DC. The first motor MG1, the second motor MG2, and the third motor MG3 are each connected to the battery 72 via the inverter 70. The torque of the first motor MG1, the second motor MG2, and the third motor MG3 is controlled by the inverter 70 controlled by the electronic control device 80, which will be described later. The output torque of the first motor MG1 is the first motor torque Tmg1 [N·m], the output torque of the second motor MG2 is the second motor torque Tmg2 [N·m], and the output torque of the third motor MG3 is the third motor torque Tmg3 [N·m]. The torque of the motors is the driving torque when the motor functions as a prime mover, and the regenerative torque when the motor functions as a generator. The battery 72 is an energy storage device that exchanges power with each of the first motor MG1, the second motor MG2, and the third motor MG3. For example, the first motor MG1, the second motor MG2, and the third motor MG3 are controlled via the inverter 70 to exchange power simultaneously. "Simultaneously" means, for example, that each of the first motor MG1, the second motor MG2, and the third motor MG3 is capable of independently powering or regenerating at the same time.

[0041] Thus, the vehicle drive system 10 comprises an engine 12, a front drive unit 20, a front drive shaft 28, a rear drive unit 60, and a rear drive shaft 38. The vehicle drive system 10 is capable of front-wheel drive, transmitting torque only to the front wheels 14f, and rear-wheel drive, transmitting torque only to the rear wheels 14r.

[0042] The front drive unit 20 comprises a first unit section U1a consisting of a first planetary gear set 40 and a second electric motor MG2, and a second unit section U2a consisting of a second planetary gear set 44 and a first electric motor MG1. The engine connecting shaft 50, which is connected to the engine 12, is connected to the first unit section U1a and the second unit section U2a as an input shaft. The engine connecting shaft 50 is the input shaft of the front drive unit 20.

[0043] The first planetary gear set 40, the second planetary gear set 44, the first electric motor MG1, and the second electric motor MG2 are arranged coaxially, and their rotational axis is the first axis C1. The first axis C1 is also the axis of the front drive unit 20. Both the first electric motor MG1 and the second electric motor MG2 are supported by a case 18. The case 18 is a non-rotating member, such as a case that houses the front drive unit 20. The case 18 corresponds to the "non-rotating member" in this invention. In Figure 1, the first unit section U1a and the second unit section U2a are depicted reflecting the arrangement of the engine 12, the first planetary gear set 40, the second planetary gear set 44, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively. The second unit section U2a is located on the engine 12 side when viewed from the first unit section U1a.

[0044] First, let's explain the first unit, U1a.

[0045] In the direction of the first axis C1, the second electric motor MG2 is positioned on the opposite side from the engine 12 when viewed from the first planetary gear set 40. The first planetary gear set 40 is a well-known double-pinion type planetary gear set having a first sun gear S1, a first pinion P1, a first carrier CA1, and a first ring gear R1. The first pinion P1 includes, for example, multiple pairs of meshing inner pinions P1a and outer pinions P1b. The engine 12 is connected to the first carrier CA1 via the engine connecting shaft 50, and the first electric motor MG1 is connected to it via the second planetary gear set 44, as will be described later. The second electric motor MG2 is connected to the first sun gear S1. The transfer 22 is connected to the first ring gear R1 via the unit output shaft 52, passing through the inside of the rotor shaft MG2r. That is, the rotation axis of the unit output shaft 52 is the first axis C1. The rotor shaft MG2r is a rotating shaft that connects the second electric motor MG2 and the first sun gear S1, and corresponds to the "connecting shaft" in this invention.

[0046] The first carrier CA1, the first sun gear S1, and the first ring gear R1 correspond to the "first rotating element," "second rotating element," and "third rotating element" in the present invention, respectively. The first planetary gear unit 40 functions as a differential mechanism that puts the first carrier CA1, the first sun gear S1, and the first ring gear R1 into a differential state. For example, the first unit U1a mechanically divides the power input to the first carrier CA1 between the first sun gear S1 and the first ring gear R1.

[0047] For example, the second motor MG2 is rotationally driven by the power divided to it by the first planetary gear unit 40. The second motor MG2 generates electricity using the power divided to it. The first planetary gear unit 40 functions as an electrically operated continuously variable transmission, in which the differential state of the first planetary gear unit 40 is controlled by the operating state of the second motor MG2. The electricity generated by the second motor MG2 is used to charge the battery 72 or to drive the first motor MG1 and the third motor MG3. The unit output shaft 52 is an output shaft from the first unit U1a to the transfer case 22, and also an output shaft from the front drive unit 20 to the transfer case 22.

[0048] Next, we will explain the second unit, U2a.

[0049] In the direction of the first axis C1, the first electric motor MG1 is positioned on the engine 12 side as viewed from the second planetary gear set 44. The second planetary gear set 44 is a well-known single-pinion type planetary gear set having a second sun gear S2, a second pinion P2, a second carrier CA2, and a second ring gear R2. The second ring gear R2 is connected to the case 18. The second sun gear S2 is connected to the first electric motor MG1. The second carrier CA2 is connected to the engine 12 and the first carrier CA1 via the engine connecting shaft 50. The engine connecting shaft 50 is connected to the first carrier CA1 and the second carrier CA2, respectively, via the inside of the rotor shaft MG1r, which connects the first electric motor MG1 and the second sun gear S2 of the second planetary gear set 44.

[0050] The second planetary gear unit 44 functions as a reduction mechanism that connects the first electric motor MG1 to the first planetary gear unit 40 in a way that allows power transmission while reducing its rotational speed to be lower than that of the first electric motor MG1. When the first electric motor MG1 functions as a prime mover, the first electric motor torque Tmg1 is added to the engine torque Te while being reduced by the second planetary gear unit 44 to a rotational speed lower than that of the first electric motor Nmg1 [rpm]. When the first electric motor MG1 functions as a generator, the first electric motor rotational speed Nmg1 is increased by the second planetary gear unit 44 to a rotational speed higher than that of the engine Ne [rpm], and the first electric motor MG1 is rotated by the engine torque Te. The engine rotational speed Ne and the first electric motor rotational speed Nmg1 are the rotational speed of the engine 12 and the rotational speed of the first electric motor MG1, respectively.

[0051] As described above, in the direction of the first axis C1, the first planetary gear unit 40 and the second planetary gear unit 44 are arranged adjacent to each other between the first motor MG1 and the second motor MG2. This allows for the integration of the first planetary gear unit 40 and the second planetary gear unit 44, and enables miniaturization of the front drive unit 20 in the axial direction. Furthermore, by making the first planetary gear unit 40 and the second planetary gear unit 44 into a single integrated part before assembling them to the front drive unit 20, the assembly work of the first planetary gear unit 40 and the second planetary gear unit 44 to the front drive unit 20 can be made more efficient.

[0052] The engine connecting shaft 50 is equipped with a brake BR. One end of the brake BR is connected to the engine connecting shaft 50, and the other end is connected to the case 18. The brake BR is an engagement device that is actuated by an actuator, such as an electric or hydraulic actuator, to selectively connect the members at both ends. The brake BR functions as a braking mechanism that selectively stops the rotation of the engine connecting shaft 50. The second carrier CA2, which is connected to the engine connecting shaft 50, can be selectively made non-rotatable or rotatable by the brake BR.

[0053] The rear drive unit 60 comprises a transmission shaft 34 and a third electric motor MG3. The third electric motor MG3 is supported, for example, by the vehicle body 62, which is a non-rotating member. When the transfer case 22 is in the front-wheel distribution mode described later, the rear drive unit 60 inputs the power of the third electric motor MG3 to the rear differential gear 36. When the transfer case 22 is in the front-to-rear wheel distribution mode described later, the rear drive unit 60 adds the power of the third electric motor MG3 to the power transmitted from the rear propeller shaft 30 to the transmission shaft 34 and inputs it to the rear differential gear 36.

[0054] The electronic control unit 80 is composed of a so-called microcomputer, which includes, for example, a CPU, RAM, ROM, input / output interface, etc. The CPU performs various controls on the vehicle 90 by performing signal processing according to a program pre-stored in the ROM, for example. For example, the electronic control unit 80 performs output control of the engine 12, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3, and also performs switching control of the drive mode of the vehicle 90, which will be described later. The electronic control unit 80 can be configured as needed, divided into units for overall control, engine control, electric motor control, etc.

[0055] The electronic control unit 80 receives various signals based on detection signals from various sensors and other devices installed in the vehicle 90. These signals include, for example, engine speed Ne, vehicle speed V [km / h], first motor speed Nmg1, second motor speed Nmg2 [rpm], third motor speed Nmg3 [rpm], accelerator opening θacc [%], shift position POSop, and charge state value SOC [%]. The second motor speed Nmg2 and third motor speed Nmg3 are the rotational speeds of the second motor MG2 and third motor MG3, respectively. The accelerator opening θacc is the amount of accelerator operation by the driver, representing the magnitude of the driver's acceleration operation. The shift position POSop is the lever position of a shift operation device (not shown), such as "P", "R", "N", or "D". The State of Charge (SOC) is the ratio of the actual amount of charge stored in the battery 72 to its predetermined full charge capacity, calculated based on factors such as the battery charge / discharge current and battery voltage.

[0056] The electronic control unit 80 outputs various control signals to various devices installed in the vehicle 90 (for example, the engine 12, inverter 70, brake BR, transfer case 22, electronically controlled coupling device 32, etc.). These various control signals include, for example, the engine control signal Se, the first motor control signal Smg1, the second motor control signal Smg2, the third motor control signal Smg3, the brake control signal Sbr, the transfer case control signal Str, and the torque control signal Sc. The engine control signal Se is a control signal for controlling the engine 12, such as the intake air volume, ignition timing, and fuel injection volume. The first motor control signal Smg1 is a control signal for controlling the first motor MG1, such as the drive current of the first motor MG1. The second motor control signal Smg2 is a control signal for controlling the second motor MG2, such as the drive current of the second motor MG2. The third motor control signal Smg3 is a control signal for controlling the third motor MG3, such as the drive current of the third motor MG3. The brake control signal Sbr is a request signal for controlling the brake BR to an ON or OFF state. In the engagement device, the ON state is synonymous with the engaged state (=connected state), and the OFF state is synonymous with the released state (=disconnected state). The transfer control signal Str is a control signal that selectively selects between a front wheel distribution mode, in which all input power is distributed to the front wheel 14f, and a front / rear wheel distribution mode, in which the input power is distributed to both the front wheel 14f and the rear wheel 14r. The torque control signal Sc is a control signal that controls the transmission torque capacity of the electronically controlled coupling device 32.

[0057] Figure 2 is a diagram showing the configuration of the vehicle drive system 10 using a collinear diagram. In Figure 2, the rear drive unit 60 is the main engine used for driving, for example, with priority over the front drive unit 20. In this case, the front drive unit 20 is considered a secondary engine. "FrOUT" in Figure 2 indicates the front wheels 14f, and "RrOUT" in Figure 2 indicates the rear wheels 14r.

[0058] The first planetary gear system 40 of the front drive unit 20 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 to RE3 of the first planetary gear system 40 is connected to an actuator such as an engine 12 or an electric motor. The collinear diagram in Figure 2 shows the three rotating elements of the first planetary gear system 40 arranged in a straight line. Expressed using the collinear diagram, in this embodiment, the first rotating element RE1 is the first carrier CA1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first ring gear R1. The engine 12 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. The front drive shaft 28, or front wheel 14f, is connected to the third rotating element RE3. Brake BR is a braking mechanism that, when engaged, stops the rotation of the first rotating element RE1. Furthermore, when the transfer case 22 is in front-to-rear wheel distribution mode, the third rotating element RE3 is connected to both the front drive shaft 28 and the rear drive shaft 38, i.e., the rear wheel 14r.

[0059] The third electric motor MG3 of the rear drive unit 60 is connected to the rear wheel 14r. Therefore, the third electric motor MG3 can be considered to be connected to the front wheel 14f via the ground (see dashed line). Furthermore, when the transfer case 22 is in front-to-rear wheel distribution mode, the third electric motor MG3 is connected to the front wheel 14f via the transmission shaft 34, electronically controlled coupling device 32, rear propeller shaft 30, transfer case 22, front propeller shaft 24, front differential gear 26, and front drive shaft 28, etc. (see dashed line). By controlling the power of the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3 to be transmitted and received simultaneously, it is possible to drive as if the third electric motor MG3 were connected to the front wheel 14f.

[0060] The electronic control unit 80 controls the engine 12, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3, and switches the drive mode of the vehicle 90 to one of several modes.

[0061] Here, when the transfer case 22 is in front-wheel distribution mode, several modes for switching the drive mode of the vehicle 90 will be explained using Figures 3 to 8. Figures 3 to 8 are diagrams that relatively represent the rotational speeds of each rotating element RE1 to RE3 of the first planetary gear unit 40 in the collinear diagram of Figure 2. In the collinear diagrams of Figures 3 to 8, the vertical lines Y1 to Y3 are arranged from left to right in the order of vertical line Y1, vertical line Y2, and vertical line Y3. Vertical line Y1 represents the rotational speed of the first sun gear S1, which is the second rotating element RE2 to which the second electric motor MG2 is connected. Vertical line Y2 represents the rotational speed of the first ring gear R1, which is the third rotating element RE3 to which the transfer case 22 (see "FrOUT" in the figure) is connected. The vertical line Y3 represents the rotational speed of the first carrier CA1, which is the first rotating element RE1 to which the first electric motor MG1 is connected via the engine 12 (see "ENG" in the figure) and the second planetary gear set 44. It also shows that the third electric motor MG3, connected to the rear wheel 14r (see "RrOUT" in the figure), is connected to the front wheel 14f via the ground. Each arrow indicates the magnitude and direction of the torque converted to the axis of each rotating element RE1 to RE3. Solid arrows indicate the torque output from each actuator, and dashed arrows indicate the torque transmitted mechanically.

[0062] Figure 3 is a collinear diagram illustrating Mode1_MG2, one of the Mode1 modes capable of BEV (Battery Electric Vehicle) driving, in which torque is generated in the first motor MG1 and the second motor MG2. In Figure 3, Mode1_MG2 is included in a plurality of modes that allow switching of the drive mode. Mode1_MG2 is a mode in which the engine 12 is stopped and torque is generated in the first motor MG1 and the second motor MG2 to perform BEV driving. In Mode1_MG2, the first motor MG1 and the second motor MG2 exchange power with the battery 72 and generate mutual torque so that the moment around the third rotating element RE3 becomes zero, thereby enabling BEV driving. At this time, for example, the torque Tmg1 of the first motor is controlled so that the engine 12 does not drag, that is, so that the rotational speed of the first rotating element RE1 becomes zero. In Mode1_MG2, the first planetary gear unit 40 is in a differential state, and torque is generated in the first motor MG1 and the second motor MG2, which is then mechanically transmitted to the output element, the third rotating element RE3. In Mode1_MG2, it is also possible to generate torque in the third motor MG3 to enable 4WD driving and increase the drive torque. Drive torque is the torque transmitted to the wheels 14 in order to move the vehicle 90.

[0063] Figure 4 is a collinear diagram illustrating Mode1_MG2_BRon, another Mode1 capable of BEV driving, which is a BEV mode in which torque is generated in the second motor MG2 while the brake BR is engaged. In Figure 4, Mode1_MG2_BRon is included in multiple modes that allow switching of the drive mode. Mode1_MG2_BRon is a mode in which BEV driving is performed by stopping the engine 12 and generating torque in the second motor MG2 while the brake BR is engaged. In Mode1_MG2_BRon, since the brake BR is engaged and the rotational speed of the first rotating element RE1 is fixed at zero, forward and reverse BEV driving is possible by the second motor MG2 using the power of the battery 72 without generating torque in the first motor MG1. At this time, BEV driving at the maximum torque of the second motor MG2 is possible. In Mode1_MG2_BRon, the first planetary gear unit 40 is in a non-differential state, and torque is generated in the second electric motor MG2, which is then mechanically transmitted to the output element, the third rotating element RE3. In addition, in Mode1_MG2_BRon, it is also possible to generate torque in the third electric motor MG3 to enable 4WD driving and increase the driving torque.

[0064] Figure 5 is a collinear diagram illustrating Mode1_MG3, another BEV mode within Mode1 that enables BEV driving, in which torque is generated in the third motor MG3 with the brake BR engaged. In Figure 5, Mode1_MG3 is included in multiple modes that allow switching of the drive mode. Mode1_MG3 is a mode in which BEV driving is performed by stopping the engine 12 and generating torque in the third motor MG3 with the brake BR engaged. In Mode1_MG3, since the brake BR is engaged and the rotational speed of the first rotating element RE1 is fixed at zero, forward and reverse BEV driving is possible using the power of the battery 72 and the third motor MG3 without dragging of the engine 12 or the first motor MG1.

[0065] Furthermore, in Mode1_MG3, it is possible to generate torque in the second electric motor MG2 to enable 4WD driving and increase the driving torque. Also, in Mode1_MG3, even if the brake BR is not engaged, it is possible to generate torque in the third electric motor MG3 to perform BEV driving. In other words, Mode1_MG3 may be a mode in which the engine 12 is stopped and torque is generated in the third electric motor MG3 to perform BEV driving.

[0066] Figure 6 is a collinear diagram illustrating the first HEV mode, or Mode 2, in which the engine 12 is rotationally driven and power is exchanged between the first electric motor MG1 and the third electric motor MG3. Figure 6(a) is a collinear diagram when torque is generated in the third electric motor MG3 by the power generated by the first electric motor MG1. Figure 6(b) is a collinear diagram when the power generated by the third electric motor MG3 is consumed by the traction of the first electric motor MG1 to apply engine braking. In Figure 6, Mode 2 is included in a plurality of modes that allow switching of the drive mode. Mode 2 is a mode that enables hybrid driving, or HEV driving, and is a series mode that enables series driving with the engine 12 as the power source.

[0067] In Figure 6(a), Mode 2 includes a mode in which the engine 12 is operated to power the first electric motor MG1 as a generator, and the third electric motor MG3 is powered by the generated electricity of the first electric motor MG1 to power the third electric motor MG3 as a prime mover. Mode 2 is a mode in which an electrically continuously variable transmission function can be realized in series mode operation with the brake BR released, using the engine 12 as the input and the rear wheels 14r as the output. In Mode 2, the power of the engine 12 is converted into power via the first electric motor MG1, and the generated electricity of the first electric motor MG1 is converted into power via the third electric motor MG3. Power conversion is the conversion between mechanical power and electrical power. In Mode 2, the explosion vibration torque of the engine 12 is less likely to be transmitted to the front drive shaft 28, so Mode 2 is advantageous for suppressing NV. "NV" is a general term for noise and vibration such as booming noise that occurs in the vehicle 90, and represents at least one of the noise and vibration in the vehicle 90. For this reason, Mode 2 is useful for use in low vehicle speed and low load ranges where quietness is required. Furthermore, Mode 2 is less susceptible to constraints such as booming noise when setting the operating point of the engine 12, allowing the engine 12 to be operated at a fuel-efficient operating point.

[0068] In Figure 6(b), Mode 2 includes a mode in which the third motor MG3 is operated as a generator, and the first motor MG1 is powered by the generated power of the third motor MG3 to rotate the engine 12. In this Mode 2, the power consumed by the powering of the first motor MG1 is supplied by the regenerative power of the third motor MG3 due to the kinetic energy of the vehicle 90, and the engine rotational speed Ne is increased by the powering of the first motor MG1. In the fuel-cut state, the rotation of the engine 12 is increased by the first motor torque Tmg1, and the torque converted to the axis of the first rotating element RE1 is a negative torque. Even when the engine 12 is operating with fuel injection, if the engine rotational speed Ne is increased by the first motor torque Tmg1 to a higher engine rotational speed Ne than in the self-sustaining operation state, the torque converted to the axis of the first rotating element RE1 is a negative torque. The positive direction of torque is the direction of torque while the engine 12 is operating. When engine 12 is running, it is equivalent to when engine 12 is generating positive torque on its own. In Mode 2 of Figure 6(b), the kinetic energy of the vehicle 90 is converted into power via the third electric motor MG3, and the power generated by the third electric motor MG3 is converted into power via the first electric motor MG1. Thus, in Mode 2, it is possible to apply engine braking. Even when engine braking is applied in Mode 2, the explosion vibration torque of engine 12 is not transmitted to the front drive shaft 28, which is advantageous for suppressing NVH (noise, vibration, and harshness).

[0069] Figure 7 is a collinear diagram illustrating the second HEV mode, or Mode 3, in which the engine 12 is operated and power is exchanged between the second electric motor MG2 and the third electric motor MG3. Figure 7(a) is a collinear diagram when torque is generated in the third electric motor MG3 by the power generated by the second electric motor MG2. Figure 7(b) is a collinear diagram when torque is generated in the second electric motor MG2 by the power generated by the third electric motor MG3. In Figure 7, Mode 3 is included in a plurality of modes that allow the drive mode to be switched. Mode 3 is a mode that enables hybrid driving, or HEV driving, and is an input split mode that enables input split driving with the engine 12 as the power source. In Mode 3, the first planetary gear set 40 is in a differential state, and torque is mechanically transmitted to the third rotating element RE3 by taking the reaction force of the engine torque Te in the second electric motor MG2. Mode 3 is a mode in which an electrically operated continuously variable transmission function can be realized by performing input split mode operation with the brake BR released, using the engine 12 as the input and the front wheels 14f and rear wheels 14r as the outputs. In Mode 3, it is possible to apply engine braking. Input split, when expressed using a collinear diagram, refers to a configuration in which two electric motors (MG2, MG3) and one engine 12 are connected to the three rotating elements of the first planetary gear unit 40, and the electric motor (MG3) is positioned as the output element (RE3).

[0070] The dashed line A1 in Figure 7(a) indicates a state in the first planetary gear unit 40 where a mechanical point is formed in which no electrical work is performed by setting the rotational speed of the second rotating element RE2 (second motor rotational speed Nmg2) to zero and thereby setting the power of the second motor MG2 to zero. At this mechanical point, the first planetary gear unit 40 has the rotational speed of the output element, the third rotating element RE3, set to the reduction side, or underdrive (U / D), relative to the engine rotational speed Ne. In other words, the mechanical point of the first planetary gear unit 40 is set to a reduction ratio α (=Nre3 / Ne<1). Note that the rotational speed Nre3 [rpm] is the rotational speed of the third rotating element. In Figure 7, Mode 3 is the U / D input split mode.

[0071] In Figure 7(a), Mode 3 includes at least a mode in which the engine 12 is operated to power the second motor MG2 as a generator, and the power generated by the second motor MG2 powers the third motor MG3 as a prime mover. In Mode 3, in addition to the mechanical transmission of torque to the third rotating element RE3, the power generated by the second motor MG2 is supplied to the third motor MG3, thereby generating torque in the third motor MG3. In Mode 3, the power of the engine 12 is converted to power via the second motor MG2, and the power generated by the second motor MG2 is converted to power via the third motor MG3. Since Mode 3 has high transmission efficiency in the high-load range, it is useful to use it in the high-load range, for example.

[0072] In Figure 7(b), Mode 3 may include a mode in which the engine 12 is running while the second motor MG2 is operated as the prime mover using the power generated by the third motor MG3. In this Mode 3, when torque is mechanically transmitted to the third rotating element RE3, the second motor MG2 is rotated in the forward direction, so the power consumed by the powering of the second motor MG2 is supplied by the regenerative power of the third motor MG3 due to the kinetic energy of the vehicle 90. In Mode 3 of Figure 7(b), the kinetic energy of the vehicle 90 is converted into power via the third motor MG3, and the power generated by the third motor MG3 is converted into power via the second motor MG2.

[0073] The vehicle drive system 10 is controlled to perform Mode 3 as shown in Figure 7(a) during normal driving, for example, when the drive mode is switched to prioritize energy efficiency. On the other hand, when the vehicle drive system 10 is switched to prioritize power performance, for example, and Mode 3 as shown in Figure 7(a) is not performed, it is controlled to perform Mode 3 as shown in Figure 7(b).

[0074] Figure 8 is a collinear diagram illustrating Mode 4, the third HEV mode, in which the engine 12 is operated and power is exchanged between the first electric motor MG1 and the second electric motor MG2. Figure 8(a) is a collinear diagram when torque is generated in the second electric motor MG2 by the power generated by the first electric motor MG1. Figure 8(b) is a collinear diagram when torque is generated in the first electric motor MG1 by the power generated by the second electric motor MG2. In Figure 8, Mode 4 is included in a plurality of modes that allow the drive mode to be switched. Mode 4 is a mode that enables hybrid driving, or HEV driving, and is an output split mode that enables output split driving with the engine 12 as the power source. In Mode 4, the first planetary gear set 40 is in a differential state, and torque is mechanically transmitted to the third rotating element RE3 by taking the reaction force of the engine torque Te in the second electric motor MG2. Mode 4 is a mode in which an electrically operated continuously variable transmission function can be realized, with the brake BR released, using the engine 12 as the input and the front wheel 14f as the output, operating in output split mode. In Mode 4, engine braking can be applied. Since the mechanical points of the first planetary gear unit 40 are set at a reduction ratio α, Mode 4 in Figure 8 is the U / D output split mode. Output split, when expressed using a collinear diagram, refers to a configuration in which two electric motors (MG1, MG2) and one engine 12 are connected to the three rotating elements of the first planetary gear unit 40, and the electric motor (MG1) is positioned at the input element (RE1) to which the engine 12 is connected.

[0075] In Figure 8(a), Mode 4 includes at least a mode in which the engine 12 is operated to power the first electric motor MG1 as a generator, and the second electric motor MG2 is powered by the electricity generated by the first electric motor MG1 as a prime mover. 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, so the power consumed by the powering of the second electric motor MG2 is supplied by the electricity generated by the first electric motor MG1 powered by the engine 12. In Mode 4, the power of the engine 12 is converted to power via the first electric motor MG1, and the electricity generated by the first electric motor MG1 is converted to power via the second electric motor MG2. Since Mode 4 has high transmission efficiency in the high vehicle speed range, it is useful to use it in the high vehicle speed range, for example.

[0076] In Figure 8(b), Mode 4 may include a mode in which the engine 12 is running while the first motor MG1 is operated as a prime mover using the power generated by the second motor MG2. In this Mode 4, when torque is mechanically transmitted to the third rotating element RE3, the second motor MG2 is set to negative rotation, so the power generated by the second motor MG2 is supplied to the first motor MG1, thereby generating torque in the first motor MG1. In Mode 4 of Figure 8(b), the power of the engine 12 is converted to power via the second motor MG2, and the power generated by the second motor MG2 is converted to power via the first motor MG1.

[0077] The vehicle drive system 10 is controlled to perform Mode 4 as shown in Figure 8(a) during normal driving, for example, when the drive mode is switched to prioritize energy efficiency. On the other hand, when the vehicle drive system 10 is switched to prioritize power performance, for example, and Mode 4 as shown in Figure 8(a) is not performed, it is controlled to perform Mode 4 as shown in Figure 8(b).

[0078] As described above using Figures 3 to 8, there are several modes in which the drive mode of the vehicle 90 can be switched when the transfer case 22 is in front-wheel distribution mode. However, the vehicle 90 can also be switched to modes other than those described above. For example, in the above-mentioned modes, different modes can be created by setting the transfer case 22 to front-to-rear wheel distribution mode.

[0079] According to this embodiment, (a) the first planetary gear unit 40 has three rotating elements RE1 to RE3 and functions as a differential mechanism, (b) the second planetary gear unit 44 functions as a reduction mechanism that connects the first electric motor MG1 to the first planetary gear unit 40 so as to transmit power while reducing its rotational speed to that of the first electric motor MG1, and (c) the engine 12 is connected to the first rotating element RE1 and the first electric motor MG1 is connected via the second planetary gear unit 44, and the second electric motor is connected to the second rotating element RE2 MG2 is connected, and the front drive shaft 28 is connected to the third rotating element RE3. (d) The first electric motor MG1, the second electric motor MG2, the first planetary gear unit 40, and the second planetary gear unit 44 are arranged on the first axis C1, which is the same axis of rotation. (e) The first electric motor MG1 and the second planetary gear unit 44, which constitute the second unit U2a, are both located on the engine 12 side when viewed from the second electric motor MG2 and the first planetary gear unit 40, which constitute the first unit U1a. For example, since the first electric motor MG1 is connected to the second planetary gear unit 44, the first electric motor MG1 and the second planetary gear unit 44 are arranged adjacent to each other in the direction of the first axis C1. For example, since the second electric motor MG2 is connected to the first sun gear S1 of the first planetary gear unit 40, the second electric motor MG2 and the first planetary gear unit 40 are arranged adjacent to each other in the direction of the first axis C1. In the direction of the first axis C1, if both the first electric motor MG1 and the second planetary gear unit 44 are located on the opposite side from the engine 12 as viewed from the second electric motor MG2 and the first planetary gear unit 40, then the engine 12 and the second planetary gear unit 44 are connected by passing through the position where the second electric motor MG2 and the first planetary gear unit 40 are located. That is, in the direction of the first axis C1, the engine connecting shaft 50 that connects the engine 12 and the second planetary gear unit 44 must be provided at the position where the rotor shaft MG2r connecting the second electric motor MG2 and the first planetary gear unit 40 is located. For example, the engine connecting shaft 50 is inserted through the inside of the rotor shaft MG2r.The unit output shaft 52 connecting the first planetary gear unit 40 and the front drive shaft 28 must be positioned to avoid all of the following: the engine connecting shaft 50 connecting the engine 12 and the second planetary gear unit 44; the rotor shaft MG2r connecting the second electric motor MG2 and the first planetary gear unit 40; and the rotor shaft MG1r connecting the first electric motor MG1 and the second planetary gear unit 44, which are located on the opposite side of the engine 12 from the first planetary gear unit 40 in the direction of the first axis C1. On the other hand, if both the first electric motor MG1 and the second planetary gear unit 44 are located on the engine 12 side from the second electric motor MG2 and the first planetary gear unit 40 in the direction of the first axis C1, then neither the first electric motor MG1 nor the second planetary gear unit 44 are located on the opposite side of the engine 12 from the first planetary gear unit 40. Therefore, the unit output shaft 52 connecting the first planetary gear unit 40 and the front drive shaft 28 only needs to be positioned to avoid both the engine connecting shaft 50 connecting the engine 12 and the second planetary gear unit 44, and the rotor shaft MG2r connecting the second electric motor MG2 and the first planetary gear unit 40. In this way, when the first electric motor MG1 and the second planetary gear unit 44 are positioned on the engine 12 side relative to the second electric motor MG2 and the first planetary gear unit 40 in the direction of the first axis C1, the constraints on positioning the unit output shaft 52 are relaxed compared to the case where they are not, making it easier to reduce the radial dimensions of the front drive unit 20. Reducing the radial dimensions of the front drive unit 20 improves, for example, the ease of mounting the front drive unit 20 onto the vehicle 90.

[0080] According to this embodiment, (a) the first planetary gear unit 40 is a double pinion type having a first sun gear S1, a first carrier CA1, and a first ring gear R1, and (b) the first rotating element RE1 is the first carrier CA1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first ring gear R1. With this double pinion type connection configuration of the first planetary gear unit 40, the mechanical point can be set with a reduction ratio α.

[0081] According to this embodiment, (a) the second planetary gear unit 44 is a single-pinion type having a second sun gear S2, a second carrier CA2, and a second ring gear R2, and (b) the second ring gear R2 is fixed to the case 18, the second sun gear S2 is connected to the first electric motor MG1, and the second carrier CA2 is connected to the first rotating element RE1. With this single-pinion type connection configuration of the second planetary gear unit 44, the second planetary gear unit 44 can connect the first electric motor MG1 to the first planetary gear unit 40 in a way that allows power to be transmitted while reducing the rotational speed of the first electric motor MG1 compared to the rotational speed of the first electric motor MG1.

[0082] In this embodiment, the first planetary gear unit 40 and the second planetary gear unit 44 are arranged adjacent to each other between the first electric motor MG1 and the second electric motor MG2. This allows for the integration of the first planetary gear unit 40 and the second planetary gear unit 44, and enables miniaturization of the front drive unit 20 in the axial direction.

[0083] In this embodiment, (a) a rear drive shaft 38 is provided, along with a rear drive unit 60 including a third electric motor MG3 connected to the rear drive shaft 38. With this configuration, for example, the drive modes of the vehicle 90 can include so-called series driving. Compared to the case where the rear drive unit 60 is not provided, a wider variety of drive modes can be realized when the rear drive unit 60 is provided. [Examples]

[0084] Figure 9 is a diagram illustrating the schematic configuration of the vehicle drive unit 110 according to Embodiment 2. The vehicle drive unit 110 is mounted on a vehicle 190. The vehicle 190 has substantially the same configuration as the vehicle 90 according to Embodiment 1 described above, but differs in that the front drive unit 20 is replaced with a front drive unit 120.

[0085] The front drive unit 120 has substantially the same configuration as the front drive unit 20 according to Embodiment 1, but differs in that the first unit part U1a is replaced by a first unit part U1a1. The front drive unit 120 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention.

[0086] The unit output shaft 56, which is the output shaft of the first unit section U1a1 and is also the output shaft of the front drive unit 120, does not pass through the inside of the rotor shaft MG2r. The rotor shaft MG2r is a rotating shaft that connects the second electric motor MG2 and the first sun gear S1, and corresponds to the "connecting shaft" in this invention. The unit output shaft 56 corresponds to the "output shaft" in this invention. The unit output shaft 56 and the first ring gear R1 are connected via a gear pair 54. The rotational axis of the unit output shaft 56 is the second axis C2, which is different from the first axis C1. The second axis C2 is, for example, parallel to the first axis C1. In this way, the unit output shaft 56 and the first ring gear R1 are connected via the gear pair 54 without passing through the inside of the rotor shaft MG2r. In other words, the front drive shaft 28 is connected to the third rotating element RE3 without passing through the inside of the rotor shaft MG2r, via the unit output shaft 56 and the gear pair 54 that transmits power between the unit output shaft 56 and the first ring gear R1. The gear pair 54 corresponds to the "power transmission mechanism" in this invention.

[0087] Similar to Embodiment 1 described above, in the direction of the first axis C1, the first planetary gear unit 40 and the second planetary gear unit 44 are arranged adjacent to each other between the first motor MG1 and the second motor MG2. Furthermore, the first carrier CA1 of the first planetary gear unit 40 and the second carrier CA2 of the second planetary gear unit 44 are arranged adjacent to each other in the direction of the first axis C1. In addition, the second pinion P2 of the second planetary gear unit 44 is supported by the second carrier CA2 from the side opposite to the engine 12. However, in this embodiment, the first pinion P1 of the first planetary gear unit 40 is supported by the first carrier CA1 from the engine 12 side.

[0088] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 1, the effects based on that configuration are achieved in the same way.

[0089] According to this embodiment, (a) the first planetary gear set 40 and the second planetary gear set 44 are arranged adjacent to each other between the first motor MG1 and the second motor MG2, (b) the first planetary gear set 40 is a double pinion type having a first sun gear S1, a first pinion P1, a first carrier CA1 and a first ring gear R1, (c) the first rotating element RE1 is the first carrier CA1, the second rotating element RE2 is the first sun gear S1, the third rotating element RE3 is the first ring gear R1, and (d) the first pinion (a) The first carrier CA1 is supported from the engine 12 side, (e) the second planetary gear set 44 is a single-pinion type having a second sun gear S2, a second pinion P2, a second carrier CA2 and a second ring gear R2, (f) the second ring gear R2 is fixed to the case 18, the second sun gear S2 is connected to the first electric motor MG1, the second carrier CA2 is connected to the first carrier CA1, and (g) the second pinion P2 is supported from the second carrier CA2 on the opposite side from the engine 12. With the above configuration (a), the first planetary gear set 40 and the second planetary gear set 44 can be integrated, and the front drive unit 120 can be made smaller in the axial direction of the front drive unit 120. With the configurations described in (b) to (g) above, the first carrier CA1 of the first planetary gear unit 40 and the second carrier CA2 of the second planetary gear unit 44 can be arranged adjacent to each other in the direction of the first axis C1. Furthermore, since the first pinion P1 of the first planetary gear unit 40 is supported by the first carrier CA1 from the engine 12 side, and the second pinion P2 of the second planetary gear unit 44 is supported by the second carrier CA2 from the opposite side of the engine 12, the inner-circumferential pinion P1a or outer-circumferential pinion P1b of the first pinion P1 and the second pinion P2 can be made common. This makes it possible to further miniaturize the front drive unit 120.

[0090] In this embodiment, (a) the second electric motor MG2 is positioned on the opposite side from the engine 12 when viewed from the first planetary gear unit 40, and (b) the front drive shaft 28 is connected to the third rotating element RE3 without passing through the inside of the rotor shaft MG2r via a unit output shaft 56 having a second axis C2 different from the first axis C1 as its axis of rotation, and a gear pair 54 that transmits power between the unit output shaft 56 and the third rotating element RE3. In this way, the unit output shaft 56 is provided to connect the front drive shaft 28 and the third rotating element RE3. Compared to the case where the unit output shaft 56 passes through the inside of the rotor shaft MG2r, when the unit output shaft 56 does not pass through the inside of the rotor shaft MG2r, it is easier to suppress an increase in the radial size of the second electric motor MG2. [Examples]

[0091] Figure 10 is a diagram illustrating the schematic configuration of the vehicle drive unit 210 according to Embodiment 3. The vehicle drive unit 210 is mounted on a vehicle 290. The vehicle 290 has substantially the same configuration as the vehicle 190 according to Embodiment 2 described above, but differs mainly in that the front drive unit 120 is replaced with a front drive unit 220, it does not have a transfer case 22, a front propeller shaft 24, a rear propeller shaft 30, and an electronically controlled coupling device 32, and the unit output shaft 56 is connected to a front differential gear 26.

[0092] The front drive unit 220 has substantially the same configuration as the front drive unit 120 according to Embodiment 2, but differs in that the first unit section U1a1 is replaced by a first unit section U1a2. The front drive unit 220 is a unit that drives the front wheel 14f of the rear wheels 14r, and corresponds to the "first drive unit" in the present invention. The unit output shaft 56, which is the output shaft of the first unit section U1a2, that is, the unit output shaft 56 of the front drive unit 220, is input to the front differential gear 26, not the transfer case 22. In other words, the unit output shaft 56 is input to the front differential gear 26 without going through the transfer case 22 and the front propeller shaft 24.

[0093] In the direction of the second axis C2, the unit output shaft 56 extends from the gear pair 54 towards the engine 12 and is connected to the front drive shaft 28.

[0094] Similar to the vehicle 190 in Embodiment 2 described above, the electronic control unit 80 can switch the drive mode of the vehicle 290 to one of several modes. However, since the transfer case 22 is not provided in this embodiment, the multiple modes do not include any that assume the transfer case 22 is in front-to-rear wheel distribution mode.

[0095] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 2, the effects based on that configuration are achieved in the same way.

[0096] In this embodiment, the unit output shaft 56 extends from the gear pair 54 toward the engine 12 and is connected to the front drive shaft 28. When the unit output shaft 56 extends from the gear pair 54 toward the engine 12 and is connected to the front drive shaft 28, the extension of the unit output shaft 56 toward the opposite side of the engine 12 from the gear pair 54 can be reduced compared to the case where it is not. This makes it easier to secure space for mounting a battery 72, for example. [Examples]

[0097] Figure 11 is a diagram illustrating the schematic configuration of the vehicle drive unit 310 according to Embodiment 4. The vehicle drive unit 310 is mounted on a vehicle 390. The vehicle 390 has substantially the same configuration as the vehicle 90 according to Embodiment 1 described above, but the main difference is that the front drive unit 20 has been replaced with a front drive unit 320. In Figure 11, parts other than the front drive unit 320 have been omitted as appropriate.

[0098] The front drive unit 320 has substantially the same configuration as the front drive unit 20 according to Embodiment 1, but differs in that the first unit section U1a is replaced by a first unit section U1b, and the second unit section U2a is replaced by a second unit section U2b. The front drive unit 320 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention. In Figure 11, the first unit section U1b and the second unit section U2b are depicted reflecting the arrangement of the engine 12, the first planetary gear unit 40, the second planetary gear unit 44, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively.

[0099] First, let's describe the first unit U1b. In the direction of the first axis C1, the second electric motor MG2 is positioned on the engine 12 side when viewed from the first planetary gear unit 40. That is, in the first unit U1b, the arrangement of the second electric motor MG2 and the first planetary gear unit 40 in the direction of the first axis C1 is the opposite of that of the first unit U1a described above. The connection relationships between the three rotating elements RE1 to RE3 of the first planetary gear unit 40 and the engine 12, the second electric motor MG2, and the transfer case 22 are the same as in the first unit U1a. The unit output shaft 52 connects the first ring gear R1 and the transfer case 22 without passing through the inside of the rotor shaft MG2r. On the other hand, the engine connecting shaft 50 is connected to the first carrier CA1 via the inside of the rotor shaft MG2r.

[0100] Next, the second unit section U2b will be described. In the direction of the first axis C1, the first electric motor MG1 is positioned on the opposite side from the engine 12 when viewed from the second planetary gear unit 44. That is, in the second unit section U2b, the arrangement of the first electric motor MG1 and the second planetary gear unit 44 in the direction of the first axis C1 is the opposite of that of the second unit section U2a described above. The connection relationship between the three rotating elements of the second planetary gear unit 44 and the engine 12, the first electric motor MG1, and the case 18 is the same as that of the second unit section U2a. The engine connecting shaft 50 is connected to the first carrier CA1 of the first planetary gear unit 40 via the inside of the rotor shaft MG1r. The rotor shaft MG1r is a rotating shaft that connects the first electric motor MG1 and the rotating elements of the second planetary gear unit 44.

[0101] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 1, the effects based on that configuration are achieved in the same way. [Examples]

[0102] Figure 12 is a diagram illustrating the schematic configuration of the vehicle drive unit 410 according to Embodiment 5. The vehicle drive unit 410 is mounted on a vehicle 490. The vehicle 490 has substantially the same configuration as the vehicle 90 according to Embodiment 1 described above, but the main difference is that the front drive unit 20 has been replaced with a front drive unit 420. In Figure 12, parts other than the front drive unit 420 have been omitted as appropriate.

[0103] The front drive unit 420 has substantially the same configuration as the front drive unit 20 according to Embodiment 1, but differs in that the first unit section U1a is replaced by a first unit section U1c, and the second unit section U2a is replaced by a second unit section U2c. The front drive unit 420 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention. The first unit section U1c has substantially the same configuration as the first unit section U1a described above, but differs in that the first planetary gear section 40 is replaced by a first planetary gear section 42. In Figure 12, the first unit section U1c and the second unit section U2c are depicted reflecting the arrangement of the engine 12, the first planetary gear section 42, the second planetary gear section 44, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively. The second unit U2c is located on the engine 12 side when viewed from the first unit U1c.

[0104] First, the first unit U1c will be described. In the direction of the first axis C1, the second electric motor MG2 is positioned on the opposite side from the engine 12 when viewed from the first planetary gear set 42. The first planetary gear set 42 is a well-known single-pinion type planetary gear set having a first sun gear S1, a first pinion P1, a first carrier CA1, and a first ring gear R1. The first planetary gear set 42 has three rotating elements: a first rotating element RE1, a second rotating element RE2, and a third rotating element RE3. In this embodiment, the first rotating element RE1 is the first ring gear R1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first carrier CA1. The engine 12 is connected to the first rotating element RE1 via the engine connecting shaft 50, and the first electric motor MG1 is connected to it via the second planetary gear set 44, as will be described later. The second rotating element RE2 is connected to the second electric motor MG2. The third rotating element RE3 is connected to the transfer 22 via the unit output shaft 52, passing through the inside of the rotor shaft MG2r. The rotor shaft MG2r is a rotating shaft that connects the second electric motor MG2 and the first sun gear S1, and corresponds to the "connecting shaft" in this invention.

[0105] Next, the second unit section U2c will be described. In the direction of the first axis C1, the first electric motor MG1 is positioned on the engine 12 side when viewed from the second planetary gear unit 44. The case 18 is connected to the second sun gear S2. The first electric motor MG1 is connected to the second ring gear R2. The engine 12 and the first ring gear R1 are connected to the second carrier CA2 via the engine connecting shaft 50. The engine connecting shaft 50 is connected to the first ring gear R1 and the second carrier CA2, respectively, via the inside of the rotor shaft MG1r.

[0106] Figure 13 is a collinear diagram illustrating the second HEV mode (input split mode) in this embodiment, in which the engine 12 is operated and power is exchanged between the second electric motor MG2 and the third electric motor MG3. Figure 13 is a collinear diagram corresponding to Figure 7(a) in Embodiment 1. In the collinear diagram of Figure 13, the vertical lines Y1 to Y3 represent the rotational speed of the first sun gear S1, which is the second rotating element RE2 to which the second electric motor MG2 is connected; the rotational speed of the first carrier CA1, which is the third rotating element RE3 to which the transfer 22 (see "FrOUT" in the figure) is connected; and the rotational speed of the first ring gear R1, which is the first rotating element RE1 to which the first electric motor MG1 is connected via the engine 12 (see "ENG" in the figure) and the second planetary gear unit 44.

[0107] The dashed line A2 in Figure 13 indicates a state in the first planetary gear unit 42 where a mechanical point is formed in which no electrical work is performed by setting the rotational speed of the second rotating element RE2 (second motor rotational speed Nmg2) to zero and thereby setting the power of the second motor MG2 to zero. At this mechanical point, the first planetary gear unit 42 has the rotational speed of the output element, the third rotating element RE3, set to the reduction side, or underdrive (U / D), relative to the engine rotational speed Ne. In other words, the mechanical point of the first planetary gear unit 42 is set to a reduction ratio α. In Figure 13, Mode 3 is the U / D input split mode.

[0108] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 1, the effects based on that configuration are achieved in the same way.

[0109] According to this embodiment, (a) the first planetary gear unit 42 is a single-pinion type having a first sun gear S1, a first carrier CA1, and a first ring gear R1, and (b) the first rotating element RE1 is the first ring gear R1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first carrier CA1. With this single-pinion type connection configuration of the first planetary gear unit 42, the mechanical point can be set with a reduction ratio α.

[0110] According to this embodiment, (a) the second planetary gear unit 44 is a single-pinion type having a second sun gear S2, a second carrier CA2, and a second ring gear R2, and (b) the second sun gear S2 is fixed to the case 18, the second ring gear R2 is connected to the first electric motor MG1, and the second carrier CA2 is connected to the first rotating element RE1. With this single-pinion type connection configuration of the second planetary gear unit 44, the second planetary gear unit 44 can connect the first electric motor MG1 to the first planetary gear unit 42 in a way that allows power to be transmitted while reducing the rotational speed of the first electric motor MG1 compared to the rotational speed of the first electric motor MG1. [Examples]

[0111] Figure 14 is a diagram illustrating the schematic configuration of the vehicle drive unit 510 according to Embodiment 6. The vehicle drive unit 510 is mounted on a vehicle 590. The vehicle 590 has substantially the same configuration as the vehicle 490 according to Embodiment 5 described above, but the main difference is that the front drive unit 420 has been replaced with a front drive unit 520. In Figure 14, parts other than the front drive unit 520 have been omitted as appropriate.

[0112] The front drive unit 520 has substantially the same configuration as the front drive unit 420 according to Embodiment 5, but differs in that the first unit section U1c is replaced by a first unit section U1d, and the second unit section U2c is replaced by a second unit section U2d. The front drive unit 520 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention. In Figure 14, the first unit section U1d and the second unit section U2d are depicted reflecting the arrangement of the engine 12, the first planetary gear unit 42, the second planetary gear unit 44, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively.

[0113] First, let's describe the first unit section U1d. In the direction of the first axis C1, the second electric motor MG2 is positioned on the engine 12 side when viewed from the first planetary gear unit 42. That is, in the first unit section U1d, the arrangement of the second electric motor MG2 and the first planetary gear unit 42 in the direction of the first axis C1 is the opposite of that of the first unit section U1c described above. The connection relationships between the three rotating elements RE1 to RE3 of the first planetary gear unit 42 and the engine 12, the second electric motor MG2, and the transfer case 22 are the same as in the first unit section U1c. The transfer case 22 is connected to the third rotating element RE3 via the unit output shaft 52, without passing through the inside of the rotor shaft MG2r. On the other hand, the engine connecting shaft 50 is connected to the first rotating element RE1 via the inside of the rotor shaft MG2r.

[0114] Next, the second unit section U2d will be described. In the direction of the first axis C1, the first electric motor MG1 is positioned on the opposite side from the engine 12 when viewed from the second planetary gear unit 44. That is, in the second unit section U2d, the arrangement of the first electric motor MG1 and the second planetary gear unit 44 in the direction of the first axis C1 is the opposite of that of the second unit section U2c described above. The connection relationship between the three rotating elements of the second planetary gear unit 44 and the engine 12, the first electric motor MG1, and the case 18 is the same as that of the second unit section U2c. The engine connecting shaft 50 is connected to the first ring gear R1 via the inside of the rotor shaft MG1r.

[0115] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 5, the effects based on that configuration are achieved in the same way. [Examples]

[0116] Figure 15 is a diagram illustrating the schematic configuration of the vehicle drive unit 610 according to Embodiment 7. The vehicle drive unit 610 is mounted on a vehicle 690. The vehicle 690 has substantially the same configuration as the vehicle 90 according to Embodiment 1 described above, but the main difference is that the front drive unit 20 has been replaced with a front drive unit 620. In Figure 15, parts other than the front drive unit 620 have been omitted as appropriate.

[0117] The front drive unit 620 has substantially the same configuration as the front drive unit 20 according to Embodiment 1, but differs in that the first unit section U1a is replaced by a first unit section U1e, and the second unit section U2a is replaced by a second unit section U2e. The front drive unit 620 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention. The second unit section U2e has substantially the same configuration as the second unit section U2a described above, but differs in that the second planetary gear section 44 is replaced by a second planetary gear section 46. In Figure 15, the first unit section U1e and the second unit section U2e are depicted reflecting the arrangement of the engine 12, the first planetary gear section 40, the second planetary gear section 46, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively. The second unit U2e is located on the engine 12 side when viewed from the first unit U1e.

[0118] First, the first unit section U1e will be described. In the direction of the first axis C1, the second electric motor MG2 is positioned on the opposite side from the engine 12 when viewed from the first planetary gear set 40. In this embodiment, the first rotating element RE1 is the first ring gear R1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first carrier CA1. The engine 12 is connected to the first rotating element RE1 via the engine connecting shaft 50, and the first electric motor MG1 is connected to it via the second planetary gear set 46, as will be described later. The second electric motor MG2 is connected to the second rotating element RE2. The transfer 22 is connected to the third rotating element RE3 via the unit output shaft 52, passing through the inside of the rotor shaft MG2r.

[0119] Next, the second unit U2e will be described. In the direction of the first axis C1, the first electric motor MG1 is positioned on the engine 12 side as seen from the second planetary gear set 46. The second planetary gear set 46 is a well-known double-pinion type planetary gear set having a second sun gear S2, a second pinion P2, a second carrier CA2, and a second ring gear R2. The second pinion P2 includes, for example, multiple pairs of inner-circumferential pinions P2a and outer-circumferential pinions P2b that mesh with each other. The case 18 is connected to the second carrier CA2. The first electric motor MG1 is connected to the second sun gear S2. The engine 12 and the first ring gear R1 are connected to the second ring gear R2 via the engine connecting shaft 50. The engine connecting shaft 50 is connected to the first ring gear R1 and the second ring gear R2, respectively, via the inside of the rotor shaft MG1r. The rotor shaft MG1r is a rotating shaft that connects the first electric motor MG1 and the rotating elements of the second planetary gear unit 46.

[0120] In the direction of the first axis C1, the first planetary gear set 40 and the second planetary gear set 46 are arranged adjacent to each other between the first motor MG1 and the second motor MG2. Therefore, the first planetary gear set 40 and the second planetary gear set 46 can be integrated, and the front drive unit 620 can be made smaller in the axial direction.

[0121] Figure 16 is a collinear diagram illustrating the second HEV mode in this embodiment, in which the engine 12 is operated and power is exchanged between the second electric motor MG2 and the third electric motor MG3. Figure 16 is a collinear diagram corresponding to Figure 7(a) in Embodiment 1. In the collinear diagram of Figure 16, the vertical lines Y1 to Y3 represent the rotational speed of the first sun gear S1, which is the second rotating element RE2 to which the second electric motor MG2 is connected; the rotational speed of the first ring gear R1, which is the first rotating element RE1 to which the first electric motor MG1 is connected via the engine 12 (see "ENG" in the figure) and the second planetary gear unit 46; and the rotational speed of the first carrier CA1, which is the third rotating element RE3 to which the transfer 22 (see "FrOUT" in the figure).

[0122] The dashed line A3 in Figure 16 indicates a state in the first planetary gear unit 40 where a mechanical point is formed in which no electrical work is performed by setting the rotational speed of the second rotating element RE2 (second motor rotational speed Nmg2) to zero and thereby setting the power of the second motor MG2 to zero. At this mechanical point, the first planetary gear unit 40 has the rotational speed of the output element, the third rotating element RE3, set to the overdrive (O / D) side relative to the engine rotational speed Ne. In other words, the mechanical point of the first planetary gear unit 40 is set to an overdrive ratio β (=Nre3 / Ne>1). In Figure 16, Mode 3 is the O / D input split mode.

[0123] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 1, the effects based on that configuration are achieved in the same way.

[0124] According to this embodiment, (a) the first planetary gear unit 40 is a double pinion type having a first sun gear S1, a first carrier CA1, and a first ring gear R1, and (b) the first rotating element RE1 is the first ring gear R1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first carrier CA1. With this double pinion type connection configuration of the first planetary gear unit 40, the mechanical point can be set at a speed increase ratio β.

[0125] According to this embodiment, (a) the second planetary gear unit 46 is a double pinion type having a second sun gear S2, a second carrier CA2, and a second ring gear R2, and (b) the second carrier CA2 is fixed to the case 18, the second sun gear S2 is connected to the first electric motor MG1, and the second ring gear R2 is connected to the first rotating element RE1. With this double pinion type connection configuration of the second planetary gear unit 46, the second planetary gear unit 46 can connect the first electric motor MG1 to the first planetary gear unit 40 in a way that allows power to be transmitted while reducing the rotational speed of the first electric motor MG1 to a speed lower than that of the first electric motor MG1. [Examples]

[0126] Figure 17 is a diagram illustrating the schematic configuration of the vehicle drive unit 710 according to Embodiment 8. The vehicle drive unit 710 is mounted on a vehicle 790. The vehicle 790 has substantially the same configuration as the vehicle 690 according to Embodiment 7 described above, but the main difference is that the front drive unit 620 has been replaced with a front drive unit 720. In Figure 17, parts other than the front drive unit 720 have been omitted as appropriate.

[0127] The front drive unit 720 has substantially the same configuration as the front drive unit 620 according to Embodiment 7, but differs in that the first unit section U1e is replaced by a first unit section U1f, and the second unit section U2e is replaced by a second unit section U2f. The front drive unit 720 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention. In Figure 17, the first unit section U1f and the second unit section U2f are depicted reflecting the arrangement of the engine 12, the first planetary gear unit 40, the second planetary gear unit 46, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively.

[0128] First, let's describe the first unit U1f. In the direction of the first axis C1, the second electric motor MG2 is positioned on the engine 12 side when viewed from the first planetary gear unit 40. That is, in the first unit U1f, the arrangement of the second electric motor MG2 and the first planetary gear unit 40 in the direction of the first axis C1 is the opposite of that of the first unit U1e described above. The connection relationships between the three rotating elements RE1 to RE3 of the first planetary gear unit 40 and the engine 12, the second electric motor MG2, and the transfer case 22 are the same as in the first unit U1e. The transfer case 22 is connected to the first carrier CA1 via the unit output shaft 52 without passing through the inside of the rotor shaft MG2r. On the other hand, the engine connecting shaft 50 is connected to the first ring gear R1 via the inside of the rotor shaft MG2r.

[0129] Next, the second unit U2f will be described. In the direction of the first axis C1, the first electric motor MG1 is positioned on the opposite side from the engine 12 when viewed from the second planetary gear unit 46. That is, in the second unit U2f, the arrangement of the first electric motor MG1 and the second planetary gear unit 46 in the direction of the first axis C1 is the opposite of that of the second unit U2e described above. The connection relationship between the three rotating elements of the second planetary gear unit 46 and the engine 12, the first electric motor MG1, and the case 18 is the same as that of the second unit U2e. The engine connecting shaft 50 is connected to the first ring gear R1 via the inside of the rotor shaft MG1r.

[0130] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 7, the effects based on that configuration are achieved in the same way. [Examples]

[0131] Figure 18 is a diagram illustrating the schematic configuration of the vehicle drive unit 810 according to Embodiment 9. The vehicle drive unit 810 is mounted on the vehicle 890. The vehicle 890 has substantially the same configuration as the vehicle 90 according to Embodiment 1 described above, but the main difference is that the front drive unit 20 has been replaced with a front drive unit 820. In Figure 18, parts other than the front drive unit 820 have been omitted as appropriate.

[0132] The front drive unit 820 has substantially the same configuration as the front drive unit 20 according to Embodiment 1, but differs in that the first unit part U1a is replaced by a first unit part U1g, and the second unit part U2a is replaced by a second unit part U2g. The front drive unit 820 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention. The first unit part U1g has substantially the same configuration as the first unit part U1a described above, but differs in that the first planetary gear device 40 is replaced by a first planetary gear device 42. The second unit part U2g has substantially the same configuration as the second unit part U2a described above, but differs in that the second planetary gear device 44 is replaced by a second planetary gear device 46. In Figure 18, the first unit section U1g and the second unit section U2g are depicted reflecting the arrangement of the engine 12, the first planetary gear unit 42, the second planetary gear unit 46, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively. The second unit section U2g is located on the engine 12 side when viewed from the first unit section U1g.

[0133] First, the first unit U1g will be described. In the direction of the first axis C1, the second electric motor MG2 is positioned on the opposite side from the engine 12 when viewed from the first planetary gear unit 42. In this embodiment, in the first planetary gear unit 42, which is a single-pinion type, the first rotating element RE1 is the first carrier CA1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first ring gear R1. The engine 12 is connected to the first rotating element RE1 via the engine connecting shaft 50, and the first electric motor MG1 is connected to it via the second planetary gear unit 46, as will be described later. The second electric motor MG2 is connected to the second rotating element RE2. The transfer 22 is connected to the third rotating element RE3 via the unit output shaft 52, passing through the inside of the rotor shaft MG2r.

[0134] Next, the second unit U2g will be described. In the direction of the first axis C1, the first electric motor MG1 is positioned on the engine 12 side when viewed from the second planetary gear unit 46. In the double-pinion type second planetary gear unit 46, the case 18 is connected to the second sun gear S2. The first electric motor MG1 is connected to the second carrier CA2. The engine 12 and the first carrier CA1 are connected to the second ring gear R2 via the engine connecting shaft 50. The engine connecting shaft 50 is connected to the first carrier CA1 and the second ring gear R2, respectively, via the inside of the rotor shaft MG1r.

[0135] Figure 19 is a collinear diagram illustrating the second HEV mode in this embodiment, in which the engine 12 is operated and power is exchanged between the second electric motor MG2 and the third electric motor MG3. Figure 19 is a collinear diagram corresponding to Figure 7(a) in Embodiment 1. In the collinear diagram of Figure 19, the vertical lines Y1 to Y3 represent the rotational speed of the first sun gear S1, which is the second rotating element RE2 to which the second electric motor MG2 is connected; the rotational speed of the first carrier CA1, which is the first rotating element RE1 to which the first electric motor MG1 is connected via the engine 12 (see "ENG" in the figure) and the second planetary gear unit 46; and the rotational speed of the first ring gear R1, which is the third rotating element RE3 to which the transfer 22 (see "FrOUT" in the figure).

[0136] The dashed line A4 in Figure 19 indicates a state in the first planetary gear unit 42 where a mechanical point is formed in which no electrical work is performed by setting the rotational speed of the second rotating element RE2 (second motor rotational speed Nmg2) to zero and thereby setting the power of the second motor MG2 to zero. At this mechanical point, the first planetary gear unit 42 has the rotational speed of the output element, the third rotating element RE3, set to the overdrive (O / D) side relative to the engine rotational speed Ne. In other words, the mechanical point of the first planetary gear unit 42 is set to the speed increase ratio β. In Figure 19, Mode 3 is the O / D input split mode.

[0137] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 1, the effects based on that configuration are achieved in the same way.

[0138] According to this embodiment, (a) the first planetary gear unit 42 is a single-pinion type having a first sun gear S1, a first carrier CA1, and a first ring gear R1, and (b) the first rotating element RE1 is the first carrier CA1, the second rotating element RE2 is the first sun gear S1, and the third rotating element RE3 is the first ring gear R1. With this single-pinion type connection configuration of the first planetary gear unit 42, the mechanical point can be set at a speed increase ratio β.

[0139] According to this embodiment, (a) the second planetary gear unit 46 is a double pinion type having a second sun gear S2, a second carrier CA2, and a second ring gear R2, and (b) the second sun gear S2 is fixed to the case 18, the second carrier CA2 is connected to the first electric motor MG1, and the second ring gear R2 is connected to the first rotating element RE1. With this double pinion type connection configuration of the second planetary gear unit 46, the second planetary gear unit 46 can connect the first electric motor MG1 to the first planetary gear unit 42 in a way that allows power to be transmitted while reducing the rotational speed of the first electric motor MG1 compared to the rotational speed of the first electric motor MG1. [Examples]

[0140] Figure 20 is a diagram illustrating the schematic configuration of the vehicle drive unit 910 according to Embodiment 10. The vehicle drive unit 910 is mounted on the vehicle 990. The vehicle 990 has substantially the same configuration as the vehicle 890 according to Embodiment 9 described above, but the main difference is that the front drive unit 820 has been replaced with a front drive unit 920. In Figure 20, parts other than the front drive unit 920 have been omitted as appropriate.

[0141] The front drive unit 920 has substantially the same configuration as the front drive unit 820 according to Embodiment 9, but differs in that the first unit section U1g is replaced by a first unit section U1h, and the second unit section U2g is replaced by a second unit section U2h. The front drive unit 920 is a unit that drives at least the front wheel 14f of the front wheel 14f and rear wheel 14r, and corresponds to the "first drive unit" in the present invention. In Figure 20, the first unit section U1h and the second unit section U2h are depicted reflecting the arrangement of the engine 12, the first planetary gear unit 42, the second planetary gear unit 46, the first electric motor MG1, and the second electric motor MG2 in the direction of the first axis C1, respectively.

[0142] First, let's describe the first unit section U1h. In the direction of the first axis C1, the second electric motor MG2 is positioned on the engine 12 side when viewed from the first planetary gear unit 42. That is, in the first unit section U1h, the arrangement of the second electric motor MG2 and the first planetary gear unit 42 in the direction of the first axis C1 is the opposite of that of the first unit section U1g described above. The connection relationships between the three rotating elements RE1 to RE3 of the first planetary gear unit 42 and the engine 12, the second electric motor MG2, and the transfer case 22 are the same as in the first unit section U1g. The transfer case 22 is connected to the first ring gear R1 via the unit output shaft 52 without passing through the inside of the rotor shaft MG2r.

[0143] Next, the second unit U2h will be described. In the direction of the first axis C1, the first electric motor MG1 is positioned on the opposite side from the engine 12 when viewed from the second planetary gear unit 46. That is, in the second unit U2h, the arrangement of the first electric motor MG1 and the second planetary gear unit 46 in the direction of the first axis C1 is the opposite of that of the second unit U2g described above. The connection relationship between the three rotating elements of the second planetary gear unit 46 and the engine 12, the first electric motor MG1, and the case 18 is the same as that of the second unit U2g. The engine connecting shaft 50 is connected to the first carrier CA1 via the inside of the rotor shaft MG1r.

[0144] According to this embodiment, by having the same configuration as in the aforementioned Embodiment 9, the effects based on that configuration are achieved in the same way.

[0145] Although each embodiment of the present invention has been described in detail above with reference to the drawings, the present invention is also applicable to other embodiments.

[0146] The "first drive unit" according to the present invention is not limited to the front drive units 20, 120, 220, 320, 420, 520, 620, 720, 820, and 920 of the above-described embodiments 1 to 10. For example, the "first drive unit" may be an arbitrary combination of one of the first unit parts U1a, U1a1, U1a2, U1b, U1c, U1d, U1e, U1f, U1g, and U1h, and one of the second unit parts U2a, U2b, U2c, U2d, U2e, U2f, U2g, and U2h. In a first drive unit combined in this manner, the first planetary gear sets 40 and 42 and the second planetary gear sets 44 and 46 may be arranged adjacent to the first motor MG1 and the second motor MG2. In such cases, the first planetary gear units 40, 42 and the second planetary gear units 44, 46 can be integrated, not limited to the aforementioned embodiments 1 to 3 and 7. For example, the first drive unit may be configured with a combination of one of the first unit parts U1a, U1a1, U1a2, U1c, U1e, U1g and one of the second unit parts U2a, U2e, U2g.

[0147] The aforementioned Embodiment 2 was a configuration in which the unit output shaft 56 and the first ring gear R1, which is the third rotating element RE3, were connected via a gear pair 54. However, the present invention is not limited to this configuration. For example, the unit output shaft 56 and the third rotating element RE3 may be connected by a chain and a sprocket. In this configuration, the chain and sprocket correspond to the "power transmission mechanism" in the present invention.

[0148] The aforementioned Embodiment 2 is a configuration in which, in the aforementioned Embodiment 1, a unit output shaft 56 is provided with a second axis C2 that is different from the first axis C1, instead of the unit output shaft 52 whose rotation axis is the first axis C1. However, the present invention is not limited to this configuration. For example, the present invention is also applicable to configurations in the aforementioned Embodiments 4 to 10 in which a unit output shaft 56 with a second axis C2 is provided instead of the unit output shaft 52 whose rotation axis is the first axis C1. In these configurations, in the direction of the first axis C1, the direction in which the first rotating element RE1 extends to connect to the engine connecting shaft 50 and the direction in which the third rotating element RE3 extends to connect to the unit output shaft 56 are on opposite sides. As a result, the connection between the third rotating element RE3 and the gear pair 54 is not obstructed by the connection between the first rotating element RE1 and the engine connecting shaft 50. In these embodiments, the unit output shaft 56 and the third rotating element RE3 may be connected by a chain and a sprocket.

[0149] The aforementioned Embodiment 3 is a configuration in which the transfer case 22, front propeller shaft 24, rear propeller shaft 30, and electronically controlled coupling device 32 are not provided, the unit output shaft 56 is connected to the front differential gear 26, and the rear drive unit 60 is replaced with a rear drive unit 260. However, the present invention is not limited to this configuration. For example, in the aforementioned Embodiments 4 to 10, the unit output shaft 56, whose rotational axis is the second axis C2, is provided instead of the unit output shaft 52, and the unit output shaft 56 extends from the gear pair 54 towards the engine 12 and is connected to the front drive shaft 28. The present invention is also applicable to a configuration in which the transfer case 22, front propeller shaft 24, rear propeller shaft 30, and electronically controlled coupling device 32 are not provided, and the unit output shaft 56 is connected to the front differential gear 26.

[0150] In the aforementioned embodiments 1 to 10, a one-way clutch may be used instead of the brake BR to stop the rotation of the first rotating element RE1. Also, in the aforementioned embodiments 1 to 10, the brake BR is not necessarily required. In this case, Mode1_MG2_BRon of Mode1 will not be executed. Furthermore, as mentioned 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.

[0151] In the aforementioned embodiments 1 to 10, the rear drive units 60 and 260 were equipped with a third electric motor MG3, but the present invention is also applicable to embodiments without a third electric motor MG3. In this embodiment, the multiple modes for switching the drive mode of the vehicle 90, etc., do not include a mode using the third electric motor MG3.

[0152] In the above-described embodiments 1 to 10, one of the front wheels 14f and rear wheels 14r to which power from the engine 12 and the second electric motor MG2 is transmitted may be the rear wheel 14r, and the other of the front wheels 14f and rear wheels 14r to which power from the third electric motor MG3 is transmitted may be the front wheel 14f. In other words, the "first drive shaft" may be the rear drive shaft 38 and the "second drive shaft" may be the front drive shaft 28.

[0153] In the aforementioned embodiments 1 to 10, in the PHEV, it is assumed that BEV driving using Mode1_MG3 will be frequently used, so the drive unit equipped with the third electric motor MG3 is considered the main engine. However, in the HEV, the drive unit equipped with the engine 12 and the second electric motor MG2 may be considered the main engine.

[0154] It should be noted that the above-described embodiment is merely one example, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0155] 10, 110, 210, 310, 410, 510, 610, 710, 810, 910: Vehicle drive unit, 12: Engine, 14f: Front wheel, 14r: Rear wheel, 18: Case (non-rotating member), 20, 120, 220, 320, 420, 520, 620, 720, 820, 920: Front drive unit (first drive unit), 28: Front drive shaft (first drive shaft), 38: Rear drive shaft (second drive shaft), 40, 42: First planetary gear unit, 44, 46: Second planetary gear unit, 54: Gear pair (power transmission) (Drive mechanism), 56: Unit output shaft (output shaft), 60: Rear drive unit (second drive unit), C1: First axis, C2: Second axis, CA1: First carrier, CA2: Second carrier, MG1: First motor, MG2: Second motor, MG2r: Rotor shaft (connecting shaft), MG3: Third motor, Nmg1: First motor rotation speed (rotation speed of the first motor), R1: First ring gear, R2: Second ring gear, RE1: First rotating element, RE2: Second rotating element, RE3: Third rotating element, S1: First sun gear, S2: Second sun gear

Claims

1. A vehicle drive system comprising an engine, a first drive unit including a first electric motor, a second electric motor, a first planetary gear set and a second planetary gear set each having three rotating elements, and a first drive shaft that drives either the front wheels or the rear wheels, The first planetary gear system has three rotating elements: a first rotating element, a second rotating element, and a third rotating element, and functions as a differential mechanism. The second planetary gear unit functions as a reduction mechanism that connects the first motor to the first planetary gear unit in a way that allows power to be transmitted while reducing its rotational speed to a speed lower than that of the first motor. The engine is connected to the first rotating element and the first electric motor is connected via the second planetary gear system, the second electric motor is connected to the second rotating element, and the first drive shaft is connected to the third rotating element. The first electric motor, the second electric motor, the first planetary gear set, and the second planetary gear set are arranged on a first axis which is the same axis of rotation. Both the first electric motor and the second planetary gear set are located on the engine side when viewed from the second electric motor and the first planetary gear set. A vehicle drive system characterized by the following features.

2. The first planetary gear system is a double pinion type having a first sun gear, a first carrier, and a first ring gear. The first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear. The vehicle drive system according to feature 1.

3. The first planetary gear system is a single-pinion type having a first sun gear, a first carrier, and a first ring gear. The first rotating element is the first ring gear, the second rotating element is the first sun gear, and the third rotating element is the first carrier. The vehicle drive system according to feature 1.

4. The first planetary gear system is a double pinion type having a first sun gear, a first carrier, and a first ring gear. The first rotating element is the first ring gear, the second rotating element is the first sun gear, and the third rotating element is the first carrier. The vehicle drive system according to feature 1.

5. The first planetary gear system is a single-pinion type having a first sun gear, a first carrier, and a first ring gear. The first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear. The vehicle drive system according to feature 1.

6. The aforementioned second planetary gear system is a single-pinion type having a second sun gear, a second carrier, and a second ring gear. One of the second sun gear and the second ring gear is fixed to a non-rotating member, the other of the second sun gear and the second ring gear is connected to the first electric motor, and the second carrier is connected to the first rotating element. The vehicle drive system according to feature 1.

7. The aforementioned second planetary gear system is a double pinion type having a second sun gear, a second carrier, and a second ring gear. One of the second sun gear and the second carrier is fixed to a non-rotating member, the other of the second sun gear and the second carrier is connected to the first electric motor, and the second ring gear is connected to the first rotating element. The vehicle drive system according to feature 1.

8. The first planetary gear set and the second planetary gear set are arranged adjacent to each other between the first motor and the second motor. The vehicle drive system according to feature 1.

9. The first planetary gear system is a double pinion type having a first sun gear, a first pinion, a first carrier, and a first ring gear. The first rotating element is the first carrier, the second rotating element is the first sun gear, and the third rotating element is the first ring gear. The first pinion is supported by the first carrier from the engine side, The aforementioned second planetary gear system is a single-pinion type having a second sun gear, a second pinion, a second carrier, and a second ring gear. The second ring gear is fixed to a non-rotating member, the second sun gear is connected to the first electric motor, and the second carrier is connected to the first carrier. The second pinion is supported by the second carrier from the side opposite to the engine. The vehicle drive system according to feature 8.

10. The second electric motor is positioned on the opposite side from the engine when viewed from the first planetary gear set. The first drive shaft is connected to the third rotating element without passing through the inside of the connecting shaft that connects the second motor and the second rotating element, via an output shaft whose rotation axis is a second axis different from the first axis, and a power transmission mechanism that transmits power between the output shaft and the third rotating element. The vehicle drive system according to feature 1.

11. The first drive shaft is a drive shaft that drives the front wheel, The output shaft extends from the power transmission mechanism towards the engine and is connected to the first drive shaft. The vehicle drive system according to claim 10.

12. The system further comprises a second drive shaft that drives the other of the front wheel and the rear wheel, and a second drive unit that includes a third electric motor connected to the second drive shaft. A vehicle drive system according to any one of claims 1 to 11.

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