Vehicle drive systems

Abstract

The present invention provides a vehicle drive system that can suppress axle movement when the parking brake is released and suppress the reduction in belt durability due to impact load when the parking lock mechanism is activated. [Solution] The vehicle drive system 10 includes an engine 12, a first planetary gear system 40 positioned on a first axis C1 and transmitting power from the engine 12, a sub-shaft 36 positioned on a second axis C2 different from the first axis C1 and outputting input power to the front drive shaft 24, a belt 38 that transmits power output from the first planetary gear system 40 to the sub-shaft 36, and a parking lock mechanism PLC that prevents the rotation of the front drive shaft 24. In the vehicle drive system 10, the parking lock mechanism PLC is provided in the power transmission path downstream of the belt 38, that is, between the belt 38 and the front wheel 14f.

Description

Technical Field

[0001] The present invention relates to a vehicle drive device including a prime mover, a power transmission mechanism that transmits power from the prime mover, a belt that transmits the power output from the power transmission mechanism to an output shaft, and a parking lock mechanism that prevents rotation of a vehicle axle.

Background Art

[0002] A vehicle drive device including a prime mover, a power transmission mechanism disposed on a first axis and transmitting power from the prime mover, an output shaft disposed on a second axis different from the first axis and outputting the input power to a vehicle axle, and a belt that transmits the power output from the power transmission mechanism to the output shaft is known. For example, the vehicle drive device described in Patent Document 1 is such a device. In the vehicle drive device described in Patent Document 1, there is no description of a parking lock mechanism that prevents rotation of a vehicle axle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the vehicle drive device described in Patent Document 1, depending on the position where the parking lock mechanism is provided, there is a risk that the vehicle axle may move due to the deflection of the belt when the parking brake (= parking brake) is released, and an impact load when the operation of the parking lock mechanism is started may be transmitted to the belt, leading to a decrease in the durability of the belt.

[0005] The present invention was made against the above circumstances, and its objective is to provide a vehicle drive system that can suppress the movement of the axle when the parking brake is released and can suppress the reduction in belt durability due to impact load when the parking lock mechanism is activated. [Means for solving the problem]

[0006] The gist of the present invention is a vehicle drive system comprising: a prime mover; a power transmission mechanism disposed on a first axis and transmitting power from the prime mover; an output shaft disposed on a second axis different from the first axis and outputting input power to an axle; a belt that transmits power output from the power transmission mechanism to the output shaft; and a parking lock mechanism that prevents the rotation of the axle, wherein the parking lock mechanism is provided in the power transmission path downstream of the belt. [Effects of the Invention]

[0007] According to the vehicle drive system of the present invention, the parking lock mechanism is provided in the power transmission path downstream of the belt. This suppresses the movement of the axle due to the deflection of the belt when the parking brake is released, and also suppresses the input of impact load from the parking lock mechanism to the belt when the operation of the parking lock mechanism is started, thereby suppressing a decrease in the durability of the belt. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the schematic configuration of a vehicle equipped with a vehicle drive system according to Example 1. [Figure 2] This is a collinear diagram explaining the BEV_MG2 mode. [Figure 3] This is a collinear diagram illustrating the series mode. [Figure 4] This is a collinear diagram illustrating the output split mode. [Figure 5]This diagram illustrates the schematic configuration of a vehicle equipped with a vehicle drive system according to Embodiment 2. [Figure 6] This diagram illustrates the schematic configuration of a vehicle equipped with a vehicle drive system according to Embodiment 3. [Modes for carrying out the invention]

[0009] 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 depicted accurately. [Examples]

[0010] Figure 1 is a diagram illustrating the schematic configuration of a vehicle 90 equipped with a vehicle drive unit 10 according to Embodiment 1.

[0011] Vehicle 90 is a hybrid vehicle. For example, vehicle 90 is a HEV (Hybrid Electric Vehicle) or a PHEV (Plug-in Hybrid Electric Vehicle). 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 left and right with respect to the forward direction of vehicle 90. 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.

[0012] The vehicle 90 is equipped with a first power transmission path PT1 between the engine 12 and the front wheels 14f. 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 device 80. In this specification, unless otherwise specified, torque, driving force, power, and force (=power) are synonymous. During two-wheel drive driving (=2WD driving), either the front wheels 14f or the rear wheels 14r are the drive wheels. During four-wheel drive driving (=4WD driving), both the front wheels 14f and the rear wheels 14r are the drive wheels. The engine 12 corresponds to the "prime mover" in this invention.

[0013] The first power transmission path PT1 is provided with, in order from the engine 12 side, a front drive unit 20, a front differential gear 22, and left and right front drive shafts 24, and the configuration is well known except for the front drive unit 20. Hereinafter, the left and right front drive shafts 24 will be simply referred to as "front drive shafts 24". The front drive unit 20 is a unit that drives the front wheels 14f. The front drive shafts 24 correspond to the "axles" in this invention.

[0014] 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 42, each having three rotating elements. The first motor MG1 and the second motor MG2 are rotating electric machines, so-called motor generators, that have the functions of both a motor and a generator, respectively, and are, for example, three-phase synchronous motors. The detailed configuration of the front drive unit 20 will be described later.

[0015] Vehicle 90 is equipped with a second power transmission path PT2 between the third electric motor MG3 and the rear wheel 14r. The third electric motor MG3 is the power source for driving. The third electric motor MG3 is a rotating electric machine, a so-called motor generator, which has at least the function of an electric motor among the functions of an electric motor and a generator, and is, for example, a three-phase synchronous motor.

[0016] In the second power transmission path PT2, in order from the third motor MG3 side, a transmission shaft 56, a rear differential gear 52, left and right rear drive shafts 54, etc. are provided, and these are of well-known configurations. The third motor MG3 is connected to the transmission shaft 56. Hereinafter, the left and right rear drive shafts 54 will be simply referred to as the "rear drive shaft 54". The transmission shaft 56 and the third motor MG3 constitute a rear drive unit 50. The rear drive unit 50 is a unit that drives the rear wheels 14r. Details of the configuration of the rear drive unit 50 will be described later. The rear drive shaft 54 corresponds to the "other axle" in the present invention.

[0017] The vehicle 90 includes an inverter 60, a battery 62, and an electronic control unit 80.

[0018] The inverter 60 is a well-known power supply circuit that converts DC to AC or AC to DC. The first motor MG1, the second motor MG2, and the third motor MG3 are each connected to the battery 62 via the inverter 60. The first motor MG1, the second motor MG2, and the third motor MG3 are each controlled in torque by the inverter 60 being controlled by the electronic control unit 80. 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 motor becomes a driving torque when those motors function as motors, and becomes a regenerative torque when those motors function as generators. The battery 62 is a power 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 so that power is exchanged simultaneously via the inverter 60. "Simultaneously" means, for example, in a state where each of the first motor MG1, the second motor MG2, and the third motor MG3 can independently perform driving or regeneration simultaneously.

[0019] As described above, the vehicle drive device 10 includes an engine 12, a front drive unit 20, a front drive shaft 24, a rear drive unit 50, and a rear drive shaft 54. The vehicle drive device 10 is capable of front-wheel drive that transmits torque only to the front wheels 14f and rear-wheel drive that transmits torque only to the rear wheels 14r.

[0020] Hereinafter, the front drive unit 20 will be described.

[0021] In the front drive unit 20, the engine 12, the first planetary gear device 40, the second planetary gear device 42, the first electric motor MG1, and the second electric motor MG2 are arranged coaxially, and their rotation axes are the first axis C1. Both the first electric motor MG1 and the second electric motor MG2 are supported by the case 18. The case 18 is a non-rotating member, for example, a case that houses the front drive unit 20 and the like.

[0022] The first planetary gear unit 40 is a well-known double-pinion type having a first sun gear S1, a first pinion P1, a first carrier CA1, and a first ring gear R1. The first pinion P1 meshes with the first sun gear S1 and the first ring gear R1, respectively. The first carrier CA1 supports the first pinion P1 so that it can rotate and revolve. The outer circumference of the rotating member on which the first ring gear R1 is provided as an inner tooth is provided with outer teeth R1o. The first pinion P1 includes, for example, a plurality of pairs of inner pinions P1a and outer pinions P1b that mesh with each other. The engine 12 is connected to the first carrier CA1 via an engine connecting shaft 30, and the first electric motor MG1 is connected via a second planetary gear unit 42, as will be described later. The engine connecting shaft 30 is the input shaft from the engine 12 to the front drive unit 20. The first sun gear S1 is connected to the second electric motor MG2 via the main shaft 32. The first ring gear R1 is connected to the sub-shaft 36 via a belt 38. Specifically, the belt 38 is wrapped around the outer teeth R1o and the driven gear 36g which is fixed to the sub-shaft 36 so as not to rotate relative to it. The belt 38 is a flat, strip-shaped member that transmits power, and includes, for example, a V-belt or a chain belt. The sub-shaft 36 is the output shaft from the front drive unit 20 to the front differential gear 22. The rotation axis of the sub-shaft 36 is the second axis C2, which is parallel to the first axis C1. The first planetary gear unit 40 corresponds to the "power transmission mechanism" in this invention. The sub-shaft 36 corresponds to the "output shaft" in this invention.

[0023] The first carrier CA1, the first sun gear S1, and the first ring gear R1 correspond to the "first rotating element RE1," "second rotating element RE2," and "third rotating element RE3" 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 planetary gear unit 40 mechanically divides the power input to the first carrier CA1 between the first sun gear S1 and the first ring gear R1.

[0024] For example, the second motor MG2 is rotationally driven by the power divided to it by the first planetary gear unit 40. For example, 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 62 or to drive the first motor MG1 or the third motor MG3.

[0025] The second planetary gear unit 42 is a well-known single-pinion type planetary gear unit having a second sun gear S2, a second pinion P2, a second carrier CA2, and a second ring gear R2. The second pinion P2 meshes with the second sun gear S2 and the second ring gear R2, respectively. The second carrier CA2 supports the second pinion P2 so that it can rotate and revolve. 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 30. The second planetary gear unit 42 functions as a reduction mechanism that connects the first electric motor MG1 to the first planetary gear unit 40 so that power can be transmitted while reducing its rotational speed below that of the first electric motor MG1. The second planetary gear unit 42 corresponds to the "reduction mechanism" in the present invention.

[0026] The engine connecting shaft 30 is equipped with a brake BR. One end of the brake BR is connected to the engine connecting shaft 30, and the other end is connected to the case 18. The brake BR is an engagement device in which the members at both ends are selectively connected by an actuator, such as an electric or hydraulic actuator. The brake BR functions as a braking mechanism that selectively stops the rotation of the engine connecting shaft 30.

[0027] The rear drive unit 50 comprises a transmission shaft 56 and a third electric motor MG3. The third electric motor MG3 is supported, for example, by a non-rotating member, the vehicle body 58. The rear drive unit 50, for example when driving in four-wheel drive mode, inputs the power of the third electric motor MG3 to the rear differential gear 52.

[0028] For example, the rear drive unit 50 is the primary engine used for propulsion, with priority given to it over the front drive unit 20. In this case, the front drive unit 20 is considered a secondary engine.

[0029] Since the third electric motor MG3 of the rear drive unit 50 is connected to the rear wheel 14r, it can be considered to be connected to the front wheel 14f via the ground. 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.

[0030] The vehicle 90 is equipped with a shift device 64, a parking lock mechanism PLC, and a parking brake 70, which are well-known configurations.

[0031] The shift positions of the shift lever 66 of the shift device 64 are, for example, the positions "P", "R", "N", and "D". "P" is the position for parking. "R" is the position for reverse driving, enabling reverse driving. "N" is the position for neutral driving. "D" is the position for forward driving, enabling forward driving.

[0032] The parking lock mechanism PLC is a well-known parking lock mechanism that can prevent the rotation of the front drive shaft 24. The parking lock mechanism PLC is located downstream of the belt 38 in the first power transmission path PT1. "Downstream of the belt 38" means between the belt 38 and the front wheel 14f in the first power transmission path PT1. For example, the parking lock mechanism PLC is located on the sub-shaft 36. When the shift position is set to "P", the parking gear 36p, which is connected to the sub-shaft 36 in a way that prevents relative rotation, is made immobile by the parking lock mechanism PLC. This also prevents the rotation of the front drive shaft 24 and the front wheel 14f connected to the sub-shaft 36. When the parking lock mechanism PLC is released, the rotation of the sub-shaft 36 is permitted. This also allows the rotation of the front drive shaft 24 and the front wheel 14f connected to the sub-shaft 36.

[0033] The parking brake 70 is a brake for keeping the vehicle 90 stationary when parked, and has a well-known configuration. The parking brake 70 includes, for example, a brake lever 72 and a brake cable 74. The amount of force applied to the brake lever 72 is converted into tension in the brake cable 74 and transmitted to, for example, the wheel brake 76 of the rear wheel 14r. The wheel brake 76 of the rear wheel 14r applies braking torque to the rear wheel 14r according to, for example, the amount of force applied to the brake lever 72 by the driver.

[0034] By the way, the belt 38 is a component with low rigidity, meaning it is easily deformed. For example, compared to the front drive shaft 24, front differential gear 22, sub-shaft 36, and first planetary gear unit 40, the belt 38 is more prone to bending in the rotational direction.

[0035] For example, when vehicle 90 is stopped on an uphill or downhill road and the parking brake 70 is engaged, if the parking brake 70 is released, vehicle 90 may slide backward or forward even if the parking lock mechanism PLC is engaged. This is because a change in rotation occurs due to the rotational deflection of the components between the parking lock mechanism PLC and the front drive shaft 24 in the first power transmission path PT1. In this embodiment, the parking lock mechanism PLC is located downstream of the belt 38 in the first power transmission path PT1. Therefore, when the parking brake 70 is released, the amount by which vehicle 90 slides backward or forward depends solely on the rotational deflection of the components in the first power transmission path PT1, i.e., the relatively rigid components excluding the belt 38.

[0036] For example, when the parking lock mechanism PLC is activated while the vehicle 90 is at a very low speed, an impact load to prevent rotation by the parking lock mechanism PLC is input to both the member located upstream of the parking lock mechanism PLC in the first power transmission path PT1 and the member located downstream of the parking lock mechanism PLC in the first power transmission path PT1. In this case, the magnitude of the impact load input to the member located downstream of the parking lock mechanism PLC is greater than the magnitude of the impact load input to the member located upstream of the parking lock mechanism PLC. This is because the impact load input to the member located upstream of the parking lock mechanism PLC is intended to stop the engine 12 and the second electric motor MG2, etc. In contrast, the impact load input to the member located downstream of the parking lock mechanism PLC is intended to stop the front wheel 14f, to which the vehicle weight is applied as a load, and the rear wheel 14r connected to the front wheel 14f via the ground. In this embodiment, the parking lock mechanism PLC is located downstream of the belt 38 in the first power transmission path PT1. Therefore, when the parking lock mechanism PLC is activated while the vehicle 90 is traveling at a very low speed, the belt 38 is subjected to an impact load that is input to a component located upstream of the parking lock mechanism PLC.

[0037] The electronic control unit 80 is configured to include, for example, a so-called microcomputer, and performs various controls on the vehicle 90 by performing signal processing according to a pre-stored program.

[0038] The electronic control unit 80 receives various signals based on detection signals from various sensors and other devices installed in the vehicle 90. These various signals include, for example, the engine speed Ne [rpm] which is the rotational speed of the engine 12, the vehicle speed V [km / h], the first motor speed Nmg1, the second motor speed Nmg2 [rpm], the third motor speed Nmg3 [rpm], the accelerator opening θacc [%], the shift position POSop, and the charge state value SOC [%]. The engine speed Ne is the rotational speed of the engine 12. The first motor speed Nmg1, the second motor speed Nmg2, and the third motor speed Nmg3 are the rotational speeds of the first motor MG1, the second motor MG2, and the 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 operation position POSop is the operating position of the shift lever 66, such as "P", "R", "N", or "D". The charge state value (SOC) is the ratio of the actual amount of charge stored in the battery 62 to a predetermined full charge capacity, calculated based on, for example, the battery charge / discharge current and battery voltage.

[0039] The electronic control unit 80 outputs various control signals to each device of the vehicle 90 (engine 12, inverter 60, brake BR, etc.), including an engine control signal Se that controls the operating state of the engine 12, and control signals Smg1, Smg2, and Smg3 of the first, second, and third motors respectively, which control the operating states of the first, second, and third motors MG1 to MG3 via the inverter 60, as well as a brake control signal Sbr that controls the open / closed state of the brake BR.

[0040] The electronic control unit 80 is configured to switch the drive mode to one of several modes by controlling the engine 12, the first electric motor MG1, the second electric motor MG2, and the third electric motor MG3. When switching the drive mode, the electronic control unit 80 controls the brake BR to engage as needed. For example, the multiple drive modes include BEV_MG2 mode, series mode, and output split mode.

[0041] Here, the multiple switchable drive modes of the vehicle 90 will be explained using Figures 2 to 4. Figures 2 to 4 are diagrams that relatively represent the rotational speeds of each rotating element RE1 to RE3 of the first planetary gear unit 40. In these collinear diagrams, the vertical lines Y1 to Y3 represent the rotating elements of the first sun gear S1, first ring gear R1, and first carrier CA1 of the first planetary gear unit 40, respectively. In Figures 2 to 4, "ENG" represents the engine 12, "FrOUT" represents the front wheel 14f, and "RrOUT" represents the rear wheel 14r. Each arrow indicates the magnitude and direction of the torque. Solid arrows indicate the torque output from each actuator, and dashed arrows indicate the transmitted torque. Figures 2-4 show the converted values ​​of the rotational speed (Nmg1, Nmg3) and torque (Tmg1, Tmg3) of the first motor MG1 and the third motor MG3, respectively, at the first carrier CA1 and the first ring gear R1.

[0042] Figure 2 is a collinear diagram illustrating the BEV_MG2 mode. The BEV_MG2 mode 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 (Battery Electric Vehicle) driving. In BEV_MG2 mode, the first motor MG1 and the second motor MG2 exchange power with the battery 62 and generate mutual torque so that the moment around the third rotating element RE3 becomes zero, thereby enabling BEV driving. At this time, the first motor torque Tmg1 is controlled so that, for example, the engine 12 does not drag, that is, so that the rotational speed of the first rotating element RE1 becomes zero. In BEV_MG2 mode, the first planetary gear set 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. Furthermore, in BEV_MG2 mode, it is possible to generate torque in the third electric motor MG3 to enable 4WD driving and increase the driving torque.

[0043] Figure 3 is a collinear diagram illustrating the series mode. The series mode is a mode in which the brake BR is released, the engine 12 is running, and the third motor MG3 outputs a positive torque Tmg3 from the third motor MG3 due to the power generated by the first motor MG1. The series mode is a mode in which HEV (Hybrid Electric Vehicle) driving is possible, and it is a mode in which series driving with the engine 12 as the power source is possible. In the series mode, the first motor torque Tmg1 is a negative torque, and the first motor MG1 is operated as a generator by the power of the engine 12, and the third motor MG3 is operated as an electric motor. In the series mode, the explosion vibration of the engine 12 is not transmitted to the front drive shaft 24, which is advantageous in terms of reducing booming noise, etc.

[0044] Figure 4 is a collinear diagram illustrating the output split mode. The output split mode is a mode in which the brake BR is released, the engine 12 is running, and the states of the first motor MG1 and the second motor MG2 are controlled so that the power balance between the two is balanced. In the output split mode, one of the first motor MG1 and the second motor MG2 is operated as a motor, and the other is operated as a generator. The output split mode is a mode in which HEV driving is possible, and it is a mode in which output split driving with the engine 12 as the power source is possible. As shown in Figure 4(a), in the output split mode, when the second motor MG2 is rotating in the forward direction, the second motor torque Tmg2 is set to a positive torque so that the second motor MG2 operates as a motor, and the first motor torque Tmg1 is set to a negative torque so that the first motor MG1 operates as a generator. As shown in Figure 4(b), in output split mode, when the second motor MG2 is rotating in the negative direction, the second motor torque Tmg2 is set to a positive torque so that the second motor MG2 operates as a generator, and the first motor torque Tmg1 is set to a positive torque so that the first motor MG1 operates as a motor. The first planetary gear unit 40 is in a differential state, and the reaction force of the combined torque Tsum (=Te+Tmg1) of the engine torque Te and the first motor torque Tmg1 is taken by the second motor MG2, thereby mechanically transmitting torque to the first ring gear R1. The third motor MG3 is in a non-driven state.

[0045] The above describes the multiple modes to which the vehicle 90's drive mode can be switched, using Figures 2-4, but the vehicle 90 can also be switched to modes other than those shown.

[0046] According to this embodiment, the vehicle drive system 10 includes an engine 12, a first planetary gear system 40 positioned on a first axis C1 and transmitting power from the engine 12, a sub-shaft 36 positioned on a second axis C2 and outputting input power to the front drive shaft 24, a belt 38 that transmits power output from the first planetary gear system 40 to the sub-shaft 36, and a parking lock mechanism PLC that prevents the rotation of the front drive shaft 24. The parking lock mechanism PLC is provided on the sub-shaft 36 downstream of the belt 38 in the first power transmission path PT1. Because the parking lock mechanism PLC is provided downstream of the belt 38 in the first power transmission path PT1 in this way, the movement of the front drive shaft 24 due to the deflection of the belt 38 when the parking brake 70 is released is suppressed compared to when it is not provided. Furthermore, since the parking lock mechanism PLC is located downstream of the belt 38 in the first power transmission path PT1, the impact load from the parking lock mechanism PLC to the belt 38 when the operation of the parking lock mechanism PLC is started is suppressed compared to when it is not located downstream, thereby suppressing a decrease in the durability of the belt 38.

[0047] According to this embodiment, (a) the power transmitted from the first planetary gear unit 40 to the sub-shaft 36 is power from the engine 12, (b) further comprising a first electric motor MG1, a second electric motor MG2, and a second planetary gear unit 42 that connects the first electric motor MG1 to the first planetary gear unit 40 in a manner that allows power to be transmitted while reducing the rotational speed Nmg1 of the first electric motor, and (c) the first planetary gear unit 40 has three rotating elements: a first rotating element RE1, a second rotating element RE2, and a third rotating element RE3. 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 42, the second electric motor MG2 is connected to the second rotating element RE2, and the sub-shaft 36 is connected to the third rotating element RE3 via a belt 38. With this configuration, for example, the drive modes of the vehicle 90 include an output split mode and a BEV_MG2 mode. As a result, when the first electric motor MG1 and the second planetary gear system 42 are provided, a wider variety of drive modes can be realized compared to when they are not provided.

[0048] In this embodiment, the first planetary gear unit 40, the second planetary gear unit 42, the first electric motor MG1, and the second electric motor MG2 are arranged on a common first axis C1. When the first planetary gear unit 40, the second planetary gear unit 42, the first electric motor MG1, and the second electric motor MG2 are arranged on a common first axis C1, the radial dimensions of the front drive unit 20 can be reduced compared to when they are not arranged on a common first axis C1.

[0049] In this embodiment, the vehicle drive system 10 further includes a third electric motor MG3 that applies power to the rear drive shaft 54. With this configuration, for example, the drive modes of the vehicle 90 can include a series mode. As a result, when a rear drive unit 50 is provided, a wider variety of drive modes can be realized compared to when the rear drive unit 50 is not provided. [Examples]

[0050] Figure 5 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 by a front drive unit 120. Therefore, in this embodiment, the explanation will focus on the parts that differ from Embodiment 1, and parts that are substantially common in function with Embodiment 1 will be given the same reference numerals and their explanations will be omitted as appropriate.

[0051] The front drive unit 120 has almost the same configuration as the front drive unit 20 described above, but the main differences are that a gear pair 134 is provided instead of the second planetary gear unit 42 as a reduction mechanism, and that the second planetary gear unit 42 is not provided.

[0052] The first electric motor MG1 is positioned on a third axis C3 parallel to the first axis C1. The first electric motor MG1 is connected to the first carrier CA1 via a gear pair 134. The gear pair 134 consists of a large-diameter gear 134a and a small-diameter gear 134b that mesh with each other. The large-diameter gear 134a is fixed to the engine connecting shaft 30 so as not to rotate relative to it, and the small-diameter gear 134b is fixed to the rotor shaft of the first electric motor MG1 so as not to rotate relative to it. The large-diameter gear 134a is larger in diameter than the small-diameter gear 134b.

[0053] The gear pair 134 functions as a reduction mechanism that connects the first electric motor MG1 to the engine 12 in a way that allows power to be transmitted while reducing its rotational speed to that of the first electric motor MG1. The gear pair 134 corresponds to the "reduction mechanism" in this invention. When the first electric motor MG1 functions as an electric motor, the gear pair 134 reduces its rotational speed to that of the first electric motor Nmg1 [rpm], and the first electric motor torque Tmg1 is added to the engine torque Te and input to the first carrier CA1. When the first electric motor MG1 functions as a generator, the gear pair 134 increases the rotational speed of the first electric motor Nmg1 to that of the engine rotational speed Ne, and the engine torque Te rotates the first electric motor MG1.

[0054] In this embodiment, as in the aforementioned Embodiment 1, the multiple drive modes include, for example, the BEV_MG2 mode, the series mode, and the output split mode.

[0055] 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]

[0056] Figure 6 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 in that the front drive unit 120 is replaced by a front drive unit 220. Therefore, in this embodiment, the explanation will focus on the parts that differ from Embodiment 2, and parts that are substantially common in function with Embodiment 2 will be denoted by the same reference numerals and their explanations will be omitted as appropriate.

[0057] The front drive unit 220 has almost the same configuration as the aforementioned front drive unit 120, but the main difference is that it does not have the first planetary gear unit 40.

[0058] The front drive unit 220 includes a drive gear 232g fixed to the main shaft 32 so as not to rotate relative to it, a driven gear 236g fixed to the sub-shaft 36 so as not to rotate relative to it, and a belt 238. The belt 238 is wrapped around the drive gear 232g and the driven gear 236g. The drive gear 232g corresponds to the "power transmission mechanism" in this invention.

[0059] In this embodiment, as in the aforementioned Embodiment 2, the multiple drive modes include, for example, the BEV_MG2 mode, the series mode, and the output split mode.

[0060] 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.

[0061] The above-described examples are embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, without departing from its spirit.

[0062] In the aforementioned embodiments 1, 2, and 3, the "prime mover" in the present invention was an engine 12, but it is not limited to this. It is not particularly limited as long as it functions as a power source for driving.

[0063] In the aforementioned embodiments 1 and 2, the first planetary gear unit 40 was of the double pinion type, but the present invention is not limited to this embodiment. For example, the present invention is also applicable to an embodiment in which the first planetary gear unit 40 is of the single pinion type.

[0064] In the aforementioned embodiments 1 and 2, the second planetary gear unit 42 was of the single type, but the present invention is not limited to this. For example, the present invention is also applicable to embodiments in which the second planetary gear unit 42 is of the double pinion type.

[0065] In the aforementioned embodiments 1 and 2, a one-way clutch may be used instead of the brake BR to stop the rotation of the first rotating element RE1. In the aforementioned embodiment 3, a one-way clutch may be used instead of the brake BR to stop the rotation of the engine 12. Furthermore, in the aforementioned embodiments 1, 2, and 3, the brake BR is not necessarily required.

[0066] In the aforementioned embodiments 1, 2, and 3, the rear drive unit 50 was equipped with a third electric motor MG3, but the present invention is also applicable to embodiments without the third electric motor MG3. In such embodiments, the multiple modes for switching the drive modes of the vehicles 90, 190, and 290 do not include modes using the third electric motor MG3.

[0067] In the aforementioned embodiments 1, 2, and 3, the power from the engine 12 and the second electric motor MG2 may be transmitted to the rear wheel 14r, and the power from the third electric motor MG3 may be transmitted to the front wheel 14f. In other words, the "axle" in this invention may be the rear drive shaft 54, and the "other axle" in this invention may be the front drive shaft 24. [Explanation of symbols]

[0068] 10, 110, 210: Vehicle drive system, 12: Engine (prime mover), 24: Left and right front drive shafts (axles), 36: Sub-shaft (output shaft), 38: Belt, 40: First planetary gear system (power transmission mechanism), 42: Second planetary gear system (reduction mechanism), 54: Left and right rear drive shafts (another axle), 134: Gear pair (reduction mechanism), 232g: Drive gear (power transmission mechanism), 238: Belt, C1: First axis, C2: Second axis, MG1: First motor, MG2: Second motor, MG3: Third motor, Nmg1: First motor rotation speed (rotation speed of the first motor), PLC: Parking lock mechanism, RE1: First rotating element, RE2: Second rotating element, RE3: Third rotating element

Claims

1. A vehicle drive system comprising: a prime mover; a power transmission mechanism positioned on a first axis and transmitting power from the prime mover; an output shaft positioned on a second axis different from the first axis and outputting the input power to the axle; a belt that transmits the power output from the power transmission mechanism to the output shaft; and a parking lock mechanism that prevents the rotation of the axle, The parking lock mechanism is provided in the power transmission path downstream of the belt. Vehicle drive system.

2. In claim 1, The aforementioned prime mover is an engine, The power transmission mechanism is a first planetary gear system, Furthermore, it includes a first electric motor, a second electric motor, and a reduction mechanism that connects the first electric 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 electric motor. The first planetary gear system has three rotating elements: a first rotating element, a second rotating element, and a third rotating element. The engine is connected to the first rotating element, and the first electric motor is connected to it via the reduction mechanism. The second electric motor is connected to the second rotating element, and the output shaft is connected to the third rotating element via the belt. Vehicle drive system.

3. In claim 2, The reduction mechanism is a second planetary gear system, The second planetary gear unit, the first motor, and the second motor are arranged on the first axis. Vehicle drive system.

4. In claim 2 or 3, Furthermore, it includes a third electric motor that applies power to an axle other than the aforementioned axle. Vehicle drive system.

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