Vehicle drive system

Abstract

To provide a simply configured vehicle drive apparatus that is improved to be incorporated in a vehicle.SOLUTION: A vehicle drive apparatus 10 disclosed includes motor housings 11, 12, a gear-box housing 13, an inverter case 14 and a PN wire 9. The motor housings 11, 12 constitute outer shrouds for a left motor 1 and a right motor 2 that drive the left and right wheels of a vehicle with power from a battery. The gear-box housing 13 houses a gear box 3 that amplifies torque of the motors 1, 2 and transmits the torque to the left and right wheels, is disposed between the motor housings 11, 12, and is arranged offset in a front-back direction with respect to the motor housings 11, 12. The inverter case 14 houses a pair of semiconductor modules 6, 7, and is arranged above the motor housings 11, 12. The PN wire 9 interconnects the battery and semiconductor modules 6, 7, and is connected from a lower surface side of the inverter case 14 so as to pass through a first space 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive device that drives the left and right wheels of a vehicle using battery power. [Background technology]

[0002] Conventionally, vehicle drive systems that use two motors (electric motors) to drive the left and right wheels of a vehicle have been known. For example, systems have been proposed in which separate motors are connected to the left and right wheels, enabling the left and right wheels to be driven independently of each other. In such vehicle drive systems, by differentiating the driving forces of the left and right motors, it is possible to generate differences in rotation speed and torque between the left and right wheels. This improves the vehicle's turning performance and vehicle body stability during turning (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-184523 Summary of the Invention [Problem to be solved by the invention]

[0004] The vehicle drive system described above has a built-in inverter for controlling the rotation state of the AC motor. The DC power of the battery installed in the vehicle is converted to AC power by the inverter and then supplied to the left and right motors. The PN line (power supply line) through which electricity flows from the battery to the inverter is inserted, for example, from the top or rear of the inverter and fastened to a bus bar inside the inverter. This tends to increase the dimensions of the inverter in the fore-and-aft direction of the vehicle, posing a problem that makes it difficult to improve vehicle mountability. Furthermore, when a suspension system or other structures (e.g., a suspension cross member, a stabilizer, etc.) are arranged around the vehicle drive system, layout constraints may make it impossible to connect the PN line to the top or rear of the inverter.

[0005] One of the objects of the present invention was invented in light of the above-mentioned problems, and is to provide a vehicle drive device that can be improved in vehicle mountability with a simple configuration. However, in addition to this object, another object of the present invention is to achieve effects derived from the respective configurations shown in the "Mode for Carrying Out the Invention" described below, which cannot be obtained with conventional technologies. [Means for solving the problem]

[0006] The disclosed vehicle drive device includes left and right motor housings that form the exterior of a left motor and a right motor that drive the left and right wheels of a vehicle using battery power; a gearbox housing that incorporates a gearbox that amplifies the torque of the left motor and the right motor and transmits it to the left and right wheels, the gearbox housing being sandwiched between the left and right motor housings and offset in the fore-and-aft direction relative to the left and right motor housings; an inverter case that incorporates a pair of semiconductor modules that convert DC power to AC power and supply power to the left motor and the right motor and is positioned above the left and right motor housings; and a PN wire that connects the battery and the semiconductor modules and is connected from the underside of the inverter case so as to pass through a first space that is convex in the fore-and-aft direction and is surrounded by the left and right motor housings and the gearbox housing. [Effects of the Invention]

[0007] According to the disclosed vehicle drive device, the vehicle mountability can be improved with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic exploded perspective view of a vehicle drive device according to an embodiment; [Figure 2] FIG. 2 is a left side view of the vehicle drive device shown in FIG. [Figure 3] 2 is a cross-sectional view illustrating the internal structure of the vehicle drive device shown in FIG. 1. [Figure 4] FIG. 2 is a perspective view for explaining an inverter of the vehicle drive device shown in FIG. [Figure 5] 5(A) to 5(C) are three-view diagrams of the inverter shown in FIG. [Figure 6] FIG. 5 is an exploded perspective view illustrating the internal structure of the inverter shown in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0009] [1. Configuration] 1 to 6 are diagrams for explaining the configuration of a vehicle drive device 10 according to this application example (embodiment). The front-rear, left-right, and up-down directions in the drawings represent directions determined with reference to the driver of the vehicle on which the vehicle drive device 10 is installed. As shown in FIG. 1, the vehicle drive device 10 is provided with a left motor 1, a right motor 2, a gearbox 3, and an inverter 4. The left motor 1 and the right motor 2 are electric motors that receive power from a battery installed in the vehicle and drive the left and right wheels of the vehicle.

[0010] The left motor 1 is connected to a power transmission path that connects to at least the left wheel axle. Similarly, the right motor 2 is connected to a power transmission path that connects to at least the right wheel axle. In electric vehicles and hybrid vehicles equipped with other drive motors and engines, the left motor 1 and right motor 2 function as yaw moment generators that generate turning force by increasing or decreasing the driving force and braking force of at least the left and right wheels. In electric vehicles not equipped with other drive motors, in addition to the above functions, they also function as a drive source for the vehicle.

[0011] The left motor 1 and the right motor 2 each incorporate electric motor elements such as a stator, rotor, and motor shaft. As shown in Figure 3, these elements are housed in left and right motor housings 11 and 12 (left motor housing 11 and right motor housing 12) that form the exterior of each motor 1 and 2. The stator has a structure in which a coil is wound around a laminated core made of, for example, laminated insulating steel plates, and is fixed to the motor housings 11 and 12. The rotor is a cylindrical rotor with a permanent magnet inserted into a laminated core made of, for example, laminated insulating steel plates. It is inserted loosely inside the stator and fixed to the axial motor shaft while being concentric with the central axis of the stator. Changing the frequency of the AC power applied to the stator changes the rotational speed of the magnetic field inside the stator, thereby changing the angular speed of the rotor and motor shaft. One end of the motor shaft is connected to a gearbox 3.

[0012] The gearbox 3 is a driving force transmission device sandwiched between the left and right motor housings 11, 12. The gearbox 3 has a gearbox housing 13 that forms the exterior and a gear mechanism built into it. The gear mechanism amplifies the torque of the left motor 1 and the right motor 2 and transmits it to the left and right wheels. The gear mechanism also includes a mechanism (such as a differential gear mechanism or a planetary gear mechanism) for generating a torque difference between the left and right wheel axles.

[0013] The gearbox housing 13 of this embodiment is disposed offset downward in the front-to-rear direction relative to the left and right motor housings 11, 12. Specifically, as shown in FIG. 2, the positional relationship between the left and right motor housings 11, 12 and the gearbox housing 13 is set so that the gearbox 3 is disposed in a position offset toward the front and downward of the vehicle in a side view, based on the rotation axis C of the left motor 1 and the right motor 2. With this layout, a basin-shaped recess 8 that is recessed downward in the front-to-rear direction is formed between the left and right motor housings 11, 12. As shown in FIG. 3, in the vehicle drive device 10 of this embodiment, the inverter 4 is disposed inside this recess 8.

[0014] The inverter 4 is a converter (DC-AC inverter) that converts power from a DC circuit (DC power) into power from an AC circuit (AC power) on the motors 1 and 2. The inverter 4 converts DC power into AC power and supplies it to both the left motor 1 and the right motor 2. A capacitor 5 and a pair of semiconductor modules 6 and 7 (left semiconductor module 6 and right semiconductor module 7) are provided inside an inverter case 14 that forms the exterior of the inverter 4. The inverter case 14 is disposed above the left and right motor housings 11 and 12 (in a recess 8 surrounded by the left and right motor housings 11 and 12 and the gearbox housing 13) and is fixed to the left and right motor housings 11 and 12. The inverter case 14 is formed by combining an inverter upper case 15 that covers the upper surfaces of the capacitor 5 and the semiconductor modules 6 and 7 and an inverter lower case 16 that covers the lower surfaces.

[0015] Here, the space of the recess 8 adjacent to the motor housings 11, 12 in the front-to-rear direction when viewed from the side is referred to as the first space 41. Furthermore, of the spaces surrounded by the left and right motor housings 11, 12 and the gearbox housing 13, the space adjacent and above the motor housings 11, 12 when viewed from the side is referred to as the second space 42. These first space 41 and second space 42 are indicated by two-dot chain lines in FIG. 2. The first space 41 is formed with a shape (convex) that protrudes in the front-to-rear direction on its front or rear side. Furthermore, the second space 42 is formed with a shape (convex) that protrudes downward on its bottom side. The inverter case 14 is disposed in the second space 42.

[0016] Capacitor 5 is an electronic component that smooths the power supplied to motors 1 and 2. In a current-controlled inverter, capacitor 5 is installed in the power supply line for AC power converted by semiconductor modules 6 and 7. In a voltage-controlled inverter, capacitor 5 is installed on the input side of DC power. Capacitor 5 functions as a kind of filter, so to speak, and plays a role in stabilizing the current supplied to motors 1 and 2.

[0017] Semiconductor modules 6 and 7 are power modules formed on a substrate (electronic circuit board) with a three-phase bridge circuit including multiple switching elements and diodes. DC power is converted into three-phase AC power by intermittently switching the connection state of each switching element. Semiconductor elements such as thyristors, IGBTs (Insulated Gate Bipolar Transistors), and power MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors) are used as switching elements. The AC power generated by one semiconductor module, 6, is supplied to the left motor 1, and the AC power generated by the other semiconductor module, 7, is supplied to the right motor 2.

[0018] As shown in Figures 1 and 2, a first bulge 31 that bulges upward is formed in the center (center in the front-to-rear direction) of inverter upper case 15. Capacitor 5 is attached to the inside of the lower side of first bulge 31 and fixed so as to be suspended from inverter upper case 15. In addition, a second bulge 32 is provided rearward of first bulge 31 in the vehicle, and a third bulge 33 is provided forward of first bulge 31 in the vehicle. Like capacitor 5, semiconductor modules 6 and 7 are also attached to the inside of the lower side of bulge 32 and 33 and fixed so as to be suspended from inverter upper case 15.

[0019] 2 and 4, the PN line 9 for power supply connecting the battery and the semiconductor modules 6, 7 is connected from the underside of the inverter case 14 so as to pass through the first space 41. The connection point between this PN line 9 and the inverter case 14 is located behind the gearbox housing 13, in the space sandwiched between the left and right motor housings 11, 12. The PN line 9 is connected to the underside of the inverter case 14 and routed downward through a position that is opposite the gearbox housing 13 in the front-to-rear direction relative to the left and right motor housings 11, 12.

[0020] 2, the PN wire 9 extending from the junction box 30 is routed to avoid the suspension cross member 29 (a suspension cross structural member). The junction box 30 is a device that relays power from the battery and supplies it to the semiconductor modules 6, 7 via the PN wire 9, and is disposed behind the inverter case 14. The PN wire 9 is connected to the rear underside of the inverter case 14 and then to the junction box 30.

[0021] The suspension cross member 29 is a member that supports the left and right wheels of the vehicle via the suspension. The gearbox housing 13 and the left and right motor housings 11, 12 are attached above the suspension cross member 29. The PN line 9 is routed so as to pass above the lower end of the suspension cross member 29. By connecting the PN line 9 to the underside of the inverter case 14 in this way, the space of the recess 8 is effectively utilized, and the overall shape of the vehicle drive device 10 becomes compact. Furthermore, since the PN line 9 can be assembled from one direction, from the rear of the vehicle, the workability of connecting the PN line 9 is greatly improved.

[0022] 5(A) to 5(C) are three-view diagrams showing the internal structure of the inverter 4, and FIG. 6 is an exploded perspective view showing the inverter 4 with the inverter lower case 16 removed, viewed diagonally upward from below. Inside the inverter case 14, a ferrite core 17, a resin plate 18, multiple bus bars 20, a control board 25, and a resin member 26 are provided. The ferrite core 17 is a component used to counter noise in the inverter 4, and is a ceramic magnetic body formed in an annular (doughnut) shape. As shown in FIGS. 5(B) and 5(C), the ferrite core 17 is disposed below the left semiconductor module 6.

[0023] The resin plate 18 is a plate-like member made of resin and arranged between the ferrite core 17 and the left semiconductor module 6, and is suspended and fixed to the inverter upper case 15. The resin plate 18 is provided with an opening 19 of a size corresponding to the hole in the ferrite core 17. A shielding layer made of a magnetic sheet that suppresses noise propagation is also provided inside the resin plate 18. This makes it difficult for electromagnetic waves generated, for example, in the left semiconductor module 6 to propagate downward from the resin plate 18, thereby suppressing electromagnetic interference with the control board 25. The control board 25 is the control board for the semiconductor modules 6 and 7.

[0024] Busbar 20 is a conductor rod for efficiently transmitting a large current, and is formed by bending a rod-shaped or plate-shaped metal to fit the installation position. Busbar 20 is routed so as to pass through ferrite core 17 and the inside of opening 19. One end of busbar 20 is connected to PN line 9 at a position that avoids ferrite core 17 when viewed from below, as shown in FIG. 5(C). The other end of busbar 20 is connected to semiconductor modules 6 and 7.

[0025] The resin member 26 is a resin member that holds the ferrite core 17, the bus bar 20, and the control board 25 of the semiconductor modules 6 and 7. As shown in FIG. 6 , the box-shaped portion 34 located directly below the ferrite core 17 is recessed downward compared to the other portions, forming a step in front of and behind the ferrite core 17. Utilizing this step, the control board 25 is suspended and fixed below the resin member 26 in front of the ferrite core 17. The control board 25 is located on the lower surface of the resin member 26, opposite the upper surface on which the semiconductor modules 6 and 7 are located. Similar to the resin plate 18, a shielding layer made of a magnetic sheet that suppresses noise propagation is provided inside the resin member 26. This further suppresses electromagnetic interference to the control board 25.

[0026] A through hole 27 having a size corresponding to the hole in the ferrite core 17 is provided in the bottom surface of the box-shaped portion 34. The bus bar 20 is provided to pass through this through hole 27 and penetrate the inside of the ferrite core 17 and the opening 19. In addition, a working hole 28 is provided in the side surface of the box-shaped portion 34 facing the front of the vehicle. The working hole 28 is an opening for inserting a tool when tightening a fastener provided at the connection point between the bus bar 20 and the left semiconductor module 6.

[0027] 6 includes pairs of a first bus bar 21, a second bus bar 22, a third bus bar 23, and a fourth bus bar 24. The first bus bar 21 is connected to the PN line 9 via a fastener and is routed along the lower surface and rear side surface of the box-shaped portion 34. The second bus bar 22 is connected to the first bus bar 21 on the lower surface side of the box-shaped portion 34, and is connected to the left semiconductor module 6 through a hole in the ferrite core 17. The left semiconductor module 6 is connected to the PN line 9 via the first bus bar 21 and the second bus bar 22, and is supplied with power from the battery.

[0028] One end of the third bus bar 23 is fastened to the left semiconductor module 6 via a fastener, and the other end is connected to the capacitor 5. One end of the fourth bus bar 24 is connected to the right semiconductor module 7, and the other end is connected to the capacitor 5. Inside the capacitor 5, the third bus bar 23 and the fourth bus bar 24 are electrically connected. The right semiconductor module 7 is connected to the PN line 9 not only via the bus bars 21 to 24 but also via the capacitor 5, and is supplied with power from the battery.

[0029] [2. Actions and Effects] (1) In the vehicle drive device 10 described above, as shown in FIG. 2 , the PN wire 9 extending from the junction box 30 is connected to the underside of the inverter case 14 so as to pass through the first space 41. This structure allows the inverter 4 to have shorter front-to-rear and up-to-down dimensions compared to, for example, a structure in which the PN wire 9 is connected to the top or rear of the inverter case 14, thereby enabling the inverter 4 to have a more compact overall shape. Furthermore, the space in the recess 8 behind the gearbox housing 13 can be effectively utilized, thereby enabling the vehicle drive device 10 to be more compact. Additionally, the PN wire 9 is surrounded by the left and right motor housings 11 and 12 and the gearbox housing 13, thereby enhancing protection for the PN wire 9. Furthermore, the PN wire 9 can be assembled from one direction, toward the rear of the vehicle, significantly improving the ease of connecting the PN wire 9. Therefore, the vehicle drive device 10 described above allows for improved vehicle mountability with a simple configuration.

[0030] (2) In the above-described vehicle drive device 10, as shown in FIG. 2, the gearbox housing 13 is disposed offset downward relative to the left and right motor housings 11, 12. The inverter case 14 is disposed in a second space 42 that is convex downward. This allows the vertical dimension of the vehicle drive device 10 to be reduced. The PN wire 9 connected to the underside of the inverter case 14 is routed downward through a position that is opposite the gearbox housing 13 in the front-to-rear direction relative to the left and right motor housings 11, 12. This allows for efficient use of dead space (the space at the rear lower side in FIG. 2) and allows the vehicle drive device 10 to be made smaller.

[0031] (3) In the above-described vehicle drive device 10, the PN line 9 is routed so as to pass above the lower end of the suspension cross member 29. With this configuration, the PN line 9 can be routed without impeding the suspension function, and the periphery of the PN line 9 can be protected by the suspension cross member 29. (4) In the above-described vehicle drive device 10, the PN line 9 is connected to the rear underside of the inverter case 14 and connected to the junction box 30. The junction box 30 is disposed in a position relatively close to and rearward of the inverter case 14. This configuration simplifies the wiring layout of the PN line 9 while avoiding interference between the PN line 9 and surrounding structures, thereby improving the workability of connecting the PN line 9.

[0032] (5) In the above-described vehicle drive device 10, as shown in FIG. 5(C), the PN line 9 is connected to the inverter case 14 at a position that avoids the ferrite core 17. This allows the PN line 9 to be connected to the bus bar 20 at a position that is approximately the same height as the ferrite core 17 in a side view, and the PN line 9 can be moved upward as a whole. For example, as shown in FIG. 2, even if an obstruction (suspension cross member 29) is present below the vehicle drive device 10, the PN line 9 can be routed without difficulty. This increases the degree of freedom in the layout of the PN line 9, the vehicle drive device 10, and various devices arranged in the vicinity thereof (e.g., suspension cross member 29, junction box 30, etc.).

[0033] [3. Modifications] The above-described embodiment is merely illustrative, and is not intended to exclude various modifications and applications of techniques not explicitly described in the present embodiment. Each configuration of the present embodiment can be modified in various ways without departing from the spirit of the present embodiment. Furthermore, each configuration of the present embodiment can be selected or combined as needed.

[0034] For example, in the above-described embodiment, the vehicle drive device 10 is illustrated in which the gearbox 3 is positioned toward the front and downward of the vehicle in a side view with respect to the rotation axis C of the motors 1 and 2. However, the gearbox 3 may be offset toward the rear and downward of the vehicle. At least, by offsetting the gearbox housing 13 downward relative to the left and right motor housings 11 and 12, it becomes easier to position the inverter case 14 using the recess 8, and it becomes easier to connect the PN wire 9 to its underside. Therefore, it is possible to obtain the same functions and effects as the above-described embodiment. [Explanation of symbols]

[0035] 1,2 Motor 3 Gearbox 4 inverters 5. Capacitors 6,7 Semiconductor modules 8 recess 9 PN line 10 Vehicle drive unit 11,12 Motor housing 13 Gearbox housing 14 Inverter case 15 Inverter upper case 16 Inverter lower case 17 Ferrite core 18 Resin Plate 19 Opening 20 Busbar 21 First bus bar 22 Second bus bar 23 Third bus bar 24 Fourth bus bar 25 Control board 26 Resin parts 27 Through hole 28 Working hole 29 Suspension cross member 30 Junction Box 31 First bulge 32 Second bulge 33 Third bulge 34 Box-shaped part 41 First Space 42 Second Space

Claims

1. left and right motor housings that form exteriors of a left motor and a right motor that drive the left and right wheels of a vehicle using power from a battery; a gearbox housing that houses a gearbox that amplifies the torque of the left motor and the right motor and transmits the amplified torque to the left and right wheels, the gearbox housing being sandwiched between the left and right motor housings and offset in the front-rear direction from the left and right motor housings; an inverter case that houses a pair of semiconductor modules that convert DC power into AC power and supply the AC power to the left motor and the right motor, and that is disposed above the left and right motor housings; a PN line connecting the battery and the semiconductor module and connected from the underside of the inverter case so as to pass through a first space that is convex in the front-rear direction and is surrounded by the left and right motor housings and the gearbox housing; A vehicle drive device comprising:

2. The gearbox housing is disposed offset downward relative to the left and right motor housings, the inverter case is disposed in a second space that is convex downward and is surrounded by the left and right motor housings and the gearbox housing, The PN wire is connected to the underside of the inverter case and routed downward through a position opposite the gearbox housing in the front-rear direction with respect to the left and right motor housings.

2. The vehicle drive system according to claim 1, wherein:

3. a suspension cross member that supports the left and right wheels of the vehicle via a suspension and to which the gearbox housing and the left and right motor housings are attached above; The PN line is routed so as to pass above the lower end of the suspension cross member.

3. The vehicle drive device according to claim 2.

4. a junction box disposed behind the inverter case and relaying power from the battery to supply the power to the semiconductor module via the PN line; The gearbox housing is disposed offset forward and downward relative to the left and right motor housings, The PN line is connected to the rear lower surface side of the inverter case and is connected to the junction box.

4. The vehicle drive system according to claim 2 or 3.

5. the inverter case incorporates a ferrite core formed in an annular shape below the semiconductor module, The PN line is connected at a position that avoids the ferrite core when viewed from below.

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

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