Vehicle drive device

Abstract

A vehicle drive device (10) comprising a motor unit (1), which has a drive motor mounted in a vehicle and a gear mechanism for transmitting torque from the motor to left and right wheels of the vehicle, and an inverter (4), which is arranged above the motor unit (1) and has a capacitor (5) that smooths power and a semiconductor module (6) that includes a plurality of switching elements, wherein the inverter (4) has a tray unit (16) for accommodating the capacitor (5) and the semiconductor module (6), and a flat plate-shaped cover (15) that is attached to the tray unit (16) and covers the capacitor (5) and the semiconductor module (6) from above. A cooling unit (20) through which a refrigerant for cooling the inverter (4) is circulated is integrated into the cover (15). The capacitor (5) and the semiconductor module (6) both are attached to a lower surface (17) of the cover (15).

Description

Technical Field

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

Background Art

[0002] Conventionally, a vehicle drive device that drives the left and right wheels of a vehicle only with a motor (electric motor) is known. For example, a device has been proposed in which individual motors are connected to each of the left and right wheels so that the left and right wheels can be driven independently of each other. In such a vehicle drive device, by making the driving forces of the left and right motors different, a rotational speed difference or a torque difference can be generated between the left and right wheels. As a result, the turning performance and the vehicle body stability during turning of the vehicle are improved (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, the inverter is installed on a partition wall that separates the accommodation space of the speed reducer and the accommodation space of the inverter. For this reason, in the accommodation space of the inverter, an excess space is likely to be generated above the inverter, and there is room for improvement in achieving compactness. In addition, the inverter includes various components such as a capacitor and a semiconductor module. However, depending on the arrangement of these components, the inverter may not be able to be formed compactly. For example, when the components of the inverter are arranged vertically one above the other, there is a problem that the vertical dimension of the inverter tends to increase. Therefore, there is a need to develop a vehicle drive device that can compactly accommodate the inverter in a limited mounting space.

[0005] In addition, the components of the inverter generate heat during inverter operation. In particular, capacitors and semiconductor modules are likely to become hot, so they are cooled by water cooling or air cooling. However, if the cooling is insufficient, it will lead to performance degradation and progressive deterioration, so it is necessary to ensure high cooling performance.

[0006] One of the objectives of this case is to provide a vehicle drive device that is devised in light of the above problems, mounts the inverter compactly, and enhances the cooling performance. In addition to this objective, it is also another objective of this case to achieve effects that can be derived from each configuration shown in the "Mode for Carrying Out the Invention" described later and that cannot be obtained by the conventional technology.

Means for Solving the Problems

[0007] The disclosed vehicle drive device includes a motor unit having a drive motor mounted on the vehicle and a gear mechanism that transmits the torque of the motor to each of the left and right wheels of the vehicle, and an inverter disposed above the motor unit and having a capacitor for smoothing power and a semiconductor module including a plurality of switching elements. The inverter has a tray portion that houses the capacitor and the semiconductor module, and a flat cover that is attached to the tray portion and covers the capacitor and the semiconductor module from above. A cooling portion through which the refrigerant for cooling the inverter flows is integrated with the cover, and both the capacitor and the semiconductor module are attached to the lower surface of the cover. The cooling unit includes a first cooling passage through which the refrigerant flows in one direction, and a second cooling passage that is formed as a space wider than the first cooling passage directly above the position where the semiconductor module is mounted and through which the refrigerant flows. The motor unit has a rotating shaft extending in the left-right direction of the vehicle and is arranged with the left and right motors spaced apart from each other in the left-right direction, and has the left and right motors for driving the left and right wheels. The gear mechanism amplifies the torque of the left and right motors and transmits it to each of the left and right wheels. The semiconductor module includes two modules used for each of the left and right motors. The second cooling passage is provided directly above the position where each of the two modules is mounted. The first cooling passage is provided so as to connect the two second cooling passages in series and surround the capacitor in three directions or from four directions.

Effects of the Invention

[0008] According to this, by adopting a layout in which the capacitor and the semiconductor module are suspended from the cover, space can be effectively utilized, so that the inverter can be mounted compactly. Further, the components of the inverter can be cooled by the refrigerant flowing through the cooling section integrated with the cover. In particular, since this cooling section is separated from the motor unit that is the heat source, it is not heated by the heat of the motor unit, and an air-cooling effect can also be expected, so that the cooling performance can be enhanced.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0010] = Outline of Vehicle Drive Device = FIG. 7 is a schematic diagram showing the configuration of a vehicle drive device 10 of the present invention. The vehicle drive device 10 of the present invention includes a motor unit 1 having a drive motor and a gear mechanism that transmits the torque of the motor to each of the left and right wheels, and an inverter 4 disposed above the motor unit 1. The inverter 4 is mounted compactly and includes a cooling section 20 that effectively cools the capacitor 5 and the semiconductor module 6 that are components of the inverter 4.

[0011] As shown in FIG. 7, in the vehicle drive device 10, the inverter case 14 of the inverter 4 is disposed above at least one of the casings (at least one of the motor housing 12 and the gearbox housing 13) provided in the motor unit 1. The inverter 4 includes a capacitor 5 that smoothes electric power and a semiconductor module 6 that includes a plurality of switching elements. The inverter 4 has a tray portion 16 that houses the capacitor 5 and the semiconductor module 6, and a cover 15 that is attached to the tray portion 16, and the inverter case 14 is configured by these tray portion 16 and cover 15.

[0012] The cover 15 is a flat member that covers the capacitor 5 and the semiconductor module 6 from above, and a cooling portion 20 through which the refrigerant for cooling the inverter 4 flows is integrated. Both the capacitor 5 and the semiconductor module 6 are attached to the lower surface 17 of the cover 15. That is, the capacitor 5 and the semiconductor module 6 are in a "hanging layout" and are cooled by the cooling portion 20 provided above them.

[0013] The cooling portion 20 is disposed at a distance from the motor unit 1, and has a first cooling passage (not shown in FIG. 7) through which the refrigerant flows in one direction, and a second cooling passage 22 formed as a space wider than the first cooling passage directly above the position where the semiconductor module 6 is attached. The refrigerant also flows in the second cooling passage 22 to effectively cool the semiconductor module 6 that is most likely to become highly heated. Note that fins, heat sinks, or the like for enhancing the cooling efficiency may be provided in the second cooling passage 22.

[0014] Hereinafter, the configuration of the vehicle drive device 10 will be described in detail with specific examples. Note that the examples described below are merely examples, and there is no intention to exclude various modifications and applications of technologies not explicitly shown in this example (and modified examples).

Example

[0015] [1. Configuration] Figures 1 to 4 and 6 are diagrams for explaining the configuration of the vehicle drive device 10 according to this application example (embodiment). The front-back, left-right, and up-down directions in the figures represent the directions defined based on the driver of the vehicle on which the vehicle drive device 10 is mounted. As shown in FIG. 1, the vehicle drive device 10 is provided with a motor unit 1 having a drive motor 2 and a gearbox 3 mounted on the vehicle, and an inverter 4. In this embodiment, a motor unit 1 including two motors 2 (electric motors) that receive power from a battery (not shown) mounted on the vehicle and drive the left and right wheels of the vehicle is exemplified.

[0016] The two motors 2 have a rotation axis C extending in the left-right direction (vehicle width direction) (in the drawing, the rotation center of the rotation axis indicated by the dashed line is labeled C). They are coaxial and arranged at a distance from each other in the left-right direction. Hereinafter, the motor 2 arranged on the left side of the vehicle is also referred to as the "left motor 2L", and the motor 2 arranged on the right side of the vehicle is also referred to as the "right motor 2R". The left motor 2L is connected to at least a power transmission path connected to the left wheel shaft. Similarly, the right motor 2R is connected to at least a power transmission path connected to the right wheel shaft. In an electric vehicle or a hybrid vehicle equipped with other drive motors or an engine, the motor 2 functions as a yaw moment generation source that generates a turning force by at least increasing or decreasing the driving force and braking force of the left and right wheels. In an electric vehicle not equipped with other drive motors, in addition to the above functions, the motor 2 also has the function of a drive source for the vehicle.

[0017] The two motors 2 of this embodiment are configured similarly to each other. Each motor 2 has a structure with built-in motor elements such as a stator, a rotor, and a motor shaft inside. As shown in FIG. 2, these elements are housed in the left and right motor housings 12 (left motor housing 12L, right motor housing 12R) that form the exterior of each motor 2 (the motor elements of each motor 2 are installed inside). The motor housing 12 is configured such that the bottom of the bottomed cylindrical body faces outward in the left-right direction, and an end bell is attached to the opening on the central side in the left-right direction.

[0018] The stator has a structure in which a coil is wound around a laminated iron core formed by laminating electromagnetic steel sheets coated with an insulating film, for example, and is a stator fixed to each motor housing 12. The rotor is, for example, a cylindrical rotor in which a permanent magnet is inserted into a laminated iron core formed by laminating electromagnetic steel sheets coated with an insulating film, and is loosely inserted inside the stator in a state concentric with the central axis of the stator and fixed to the shaft-shaped motor shaft. By changing the frequency of the alternating current power supplied to the stator, the rotational speed of the magnetic field inside the stator changes, and the angular velocity of the rotor and the motor shaft is changed. One end of the motor shaft is connected to the gearbox 3. The left motor 2L is disposed on the left side of the gearbox 3, and the right motor 2R is disposed on the right side of the gearbox 3.

[0019] The gearbox 3 is a driving force transmission device sandwiched between the left motor housing 12L and the right motor housing 12R. This gearbox 3 has a gearbox housing 13 forming an exterior and a gear mechanism built therein. The gear mechanism is a mechanism that amplifies the torque of the left motor 2L and the right motor 2R and transmits it to the left and right wheels. Further, the gear mechanism includes a mechanism (for example, a differential gear mechanism or a planetary gear mechanism) for generating a torque difference between the left wheel shaft and the right wheel shaft.

[0020] The gearbox housing 13 of the present embodiment is disposed offset downward with respect to the left and right motor housings 12L, 12R. Specifically, with reference to the rotation axis C of the motor 2, the positional relationship between the left and right motor housings 12L, 12R and the gearbox housing 13 is set so that the gearbox 3 is disposed at a position offset downward and forward (in the radial direction of the left and right motors 2) in a side view. With such a layout, the gearbox 3 forms a recess 8 that is recessed downward together with the motor housings 12L, 12R. As shown in FIG. 2, the recess 8 has a basin shape that is recessed downward between the left and right motor housings 12L, 12R.

[0021] The inverter 4 is a converter (DC-AC inverter) that mutually converts the power of the DC circuit (DC power) and the power of the AC circuit on the motor 2 side (AC power). This inverter 4 has a function of converting DC power into AC power and supplying power to both of the left and right motors 2. The inverter 4 is disposed in the mounting space S (the two-dot chain line in FIG. 2) above the left and right motors 2 and the gearbox 3 (i.e., the motor unit 1). This mounting space S is a space formed between the vehicle drive device 10 and the surrounding devices and the vehicle body at the position where the vehicle drive device 10 is mounted, and includes the recess 8 between the motor housings 12L and 12R and the space above the motor housings 12L and 12R, and is T-shaped in a front view.

[0022] In addition, in the present embodiment, the upper end of each motor housing 12 is located directly above the rotation axis C of each motor 2 (the portion overlapping the rotation axis C in a top view). For this reason, the portion of the mounting space S above the motor housing 12 (the space corresponding to the horizontal bar of the T shape) has the smallest area directly above the rotation axis C. In other words, the mounting space S is secured largely at a position shifted from the rotation axis C rather than at a position overlapping the rotation axis C in a top view.

[0023] As shown in FIG. 1, the inverter 4 includes a capacitor 5 for smoothing power and a semiconductor module 6 including a plurality of switching elements. The capacitor 5 and the semiconductor module 6 are built in an inverter case 14 that forms the exterior of the inverter 4. Note that the components of the inverter 4 include not only the capacitor 5 and the semiconductor module 6 but also, for example, a current sensor (not shown) for detecting the current value of the inverter 4. Components other than the capacitor 5 and the semiconductor module 6 are also built in the inverter case 14 together with the capacitor 5 and the semiconductor module 6.

[0024] The inverter case 14 is disposed in the mounting space S and fixed to the left and right motor housings 12L and 12R. The inverter case 14 is formed by combining a tray portion (inverter lower case) 16 that houses the capacitor 5 and the semiconductor module 6, and a flat cover (inverter upper case) 15 that covers the capacitor 5 and the semiconductor module 6 from above. The tray portion 16 of the present embodiment is provided separately from the gearbox 3 (gearbox housing 13). However, the tray portion 16 may be provided integrally with the gearbox 3 (as a part of the gearbox housing 13).

[0025] The capacitor 5 is an electronic component having a larger thickness dimension (dimension in the vertical direction) compared to other components (semiconductor module 6 and current sensor) of the inverter 4. In the present embodiment, one capacitor 5 is used for both the left and right motors 2L and 2R. The capacitor 5 is interposed in the power supply line of the AC power converted by the semiconductor module 6 in a current control type inverter, and is interposed on the input side of the DC power in a voltage control type inverter. The capacitor 5 functions as a kind of filter and plays a role of stabilizing the current supplied to the motor 2.

[0026] The semiconductor module 6 is a power module formed by forming a three-phase bridge circuit including a plurality of switching elements, diodes, etc. on a substrate (substrate for electronic circuit). By intermittently switching the connection state of each switching element, DC power is converted into three-phase AC power. As the switching element, a semiconductor element such as a thyristor, IGBT (Insulated Gate Bipolar Transistor), or power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) is used.

[0027] The semiconductor module 6 of this embodiment includes left and right (a pair of) modules 6L and 6R (left module 6L and right module 6R) used for each of the left and right motors 2L and 2R. The left and right modules 6L and 6R are provided separately from each other. The left module 6L is a semiconductor module dedicated to the left motor 2L. The AC power generated by the left module 6L is supplied to the left motor 2L. On the other hand, the right module 6R is a semiconductor module dedicated to the right motor 2R. The AC power generated by the right module 6R is supplied to the right motor 2R.

[0028] Regarding the arrangement of the inverter 4 in this embodiment, the capacitor 5 with the largest thickness dimension is arranged in the recess 8 (inside the recess 8 or directly above the recess 8). Further, the semiconductor module 6 is arranged at a position different from both the capacitor 5 and each rotation axis C inside the recess 8 or directly above the recess 8 in a top view. Therefore, in a top view, the capacitor 5 is located between the left and right motor housings 12L and 12R, and the semiconductor module 6 is displaced in the front-rear direction and the left-right direction with respect to the capacitor 5 and the rotation axis C and does not overlap with the capacitor 5 and the rotation axis C. In this embodiment, the left module 6L is arranged behind the capacitor 5 and the right module 6R is arranged in front of the capacitor 5, but this arrangement may be reversed.

[0029] The inverter case 14 has a shape corresponding to the arrangement of the capacitor 5 and the semiconductor module 6 and the like so as to be able to accommodate the components of the inverter 4. In this embodiment, since both the capacitor 5 and the semiconductor module 6 are arranged so as to overlap the recess 8 in the vertical direction, that is, inside the recess 8 or directly above the recess 8, the inverter case 14 has a shape corresponding to the shape of the recess 8 in a top view, in other words, a substantially rectangular shape that is long in the front-rear direction in a top view.

[0030] As shown in FIGS. 2 and 3, both the capacitor 5 and the semiconductor module 6 are attached to the lower surface 17 of the cover 15 (hereinafter also referred to as the "cover lower surface 17"). The cover lower surface 17 is the inner surface facing the tray portion 16 side (lower side) when the cover 15 is attached to the tray portion 16. The capacitor 5 and the semiconductor module 6 attached to the cover lower surface 17 are accommodated in the tray portion 16 in a state of being suspended from the cover lower surface 17.

[0031] As shown in FIGS. 1 and 3, the cover 15 of this embodiment has a flat plate portion 23 attached to the periphery of the tray portion 16, a convex portion 24 formed convexly upward from the flat plate portion 23 and accommodating the capacitor 5, and a cooling portion 20 through which a refrigerant for cooling the capacitor 5 and the semiconductor module 6 flows. The cooling portion 20 is disposed at a distance from the motor 2 and the gearbox 3, and has a first cooling passage 21 through which the refrigerant flows in one direction and a second cooling passage 22 formed as a space wider than the first cooling passage 21. The configuration of the cooling portion 20 will be described later.

[0032] The flat plate portion 23 is a portion that closes an opening formed by the periphery of the tray portion 16 and is a portion where the cooling portion 20 integrated with the cover 15 is provided. The convex portion 24 has a shape that bulges upward at the central portion (central in the front-rear direction) of the cover 15 (flat plate portion 23). The capacitor 5 is fixed to a position on the cover lower surface 17 corresponding to the convex portion 24 so as to be in a state of being suspended from the convex portion 24. That is, the convex portion 24 is formed to bulge into a shape that can at least include the capacitor 5 (here, a substantially rectangular parallelepiped shape).

[0033] The cover 15 of this embodiment further has two bulging portions 25 (left bulging portion 25L and right bulging portion 25R) that bulge upward in the front-back direction of the convex portion 24. Each bulging portion 25 has a convex shape with a smaller dimension in the vertical direction (the amount of bulge from the flat plate portion 23) compared to the convex portion 24, and has a bottom surface flush with the flat plate portion 23. That is, each bulging portion 25 is hollow and has a space as the second cooling passage 22 inside. Below each of the bulging portions 25L and 25R, the respective modules 6L and 6R are arranged. The left and right modules 6L and 6R are respectively fixed to positions on the lower surface 17 of the cover corresponding to the bulging portions 25L and 25R so as to be in a state of being suspended from the flat plate portion 23.

[0034] As shown in FIGS. 1, 3, 4, and 6, the second cooling passage 22 is integrally formed with the cover 15 and is provided in two bulging portions 25L and 25R that bulge upward from the flat plate portion 23. The second cooling passage 22 includes a left second cooling passage 22L and a right second cooling passage 22R that respectively cool the left and right modules 6L and 6R. The left second cooling passage 22L and the right second cooling passage 22R are respectively provided directly above the positions where the left module 6L and the right module 6R are attached, and actively cool the semiconductor module 6 by the refrigerant flowing inside. It is preferable that fins, heat sinks, etc. for enhancing the cooling efficiency are provided in the second cooling passage 22.

[0035] As shown in FIGS. 1, 3, and 4, the first cooling passage 21 is also integrally formed with the cover 15 and has a tubular shape that bulges upward from the flat plate portion 23. Inside the first cooling passage 21, a space (hollow portion) through which the refrigerant flows is provided. The first cooling passage 21 of this embodiment includes a rear supply passage 21a and a rear discharge passage 21b connected to the left second cooling passage 22L in the rear bulging portion 25L, a front supply passage 21d and a front discharge passage 21e connected to the right second cooling passage 22R in the front bulging portion 25R, and a connection passage 21c connecting the rear discharge passage 21b and the front supply passage 21d.

[0036] The two supply paths 21a and 21d and the two discharge paths 21b and 21e all extend along the left - right direction. The rear supply path 21a extends rightward from the rear bulging portion 25L, and the rear discharge path 21b extends leftward from the rear bulging portion 25L. On the other hand, the front supply path 21d extends leftward from the front bulging portion 25R, and the front discharge path 21e extends rightward from the front bulging portion 25R. The connection path 21c is arranged to the left of the convex portion 24 and extends along the front - rear direction. Thus, the first cooling passage 21 composed of the five flow paths 21a - 21e connects the two second cooling passages 22L and 22R in series and is formed so as to surround the condenser 5 arranged at the convex portion 24 from three directions, and cools the condenser 5 with the refrigerant flowing through the first cooling passage 21.

[0037] The cooling part 20 is formed on the flat plate part 23 so as to overlap the convex part 24 when viewed from a direction orthogonal to the up - down direction. In other words, the vertical position of the cooling part 20 is set to coincide with (or be included in) the vertical position of the convex part 24. In this embodiment, the cooling part 20 is formed such that each of the two supply paths 21a and 21d and the two discharge paths 21b and 21e overlaps the convex part 24 when viewed from the front - rear direction, and the connection path 21c overlaps the convex part 24 when viewed from the left - right direction. Also, pipes 28 and 29 are respectively connected to the rear supply path 21a and the front discharge path 21e.

[0038] As shown by the white arrows in FIG. 4, refrigerant is supplied to the first cooling passage 21 from the pipe 28. This refrigerant is supplied to the left second cooling passage 22L through the rear supply path 21a, cools the left module 6L via, for example, a heat sink, and then is discharged to the rear discharge path 21b. This refrigerant is supplied to the front supply path 21d through the connection path 21c, supplied from the front supply path 21d to the right second cooling passage 22R, cools the right module 6R via a heat sink (not shown in the figure) as well, and then is discharged to the front discharge path 21e. The refrigerant discharged to the front discharge path 21e is discharged from the pipe 29 to the outside of the inverter 4.

[0039] In addition, in the first cooling passage 21 of the present embodiment, the portion extending in the left - right direction is inclined upward toward the outer side in the left - right direction within the mounting space S. Specifically, as shown in FIGS. 2 and 6, the rear discharge passage 21b and the front supply passage 21d extending leftward from the bulging portion 25 are linearly inclined upward so as to go upward as they are separated from the bulging portion 25. Thereby, as shown in FIG. 2, within the T - shaped mounting space S in the front view, interference between the first cooling passage 21 and surrounding objects (for example, the motor housing 12) is avoided, so that the inverter 4 can be arranged more compactly.

[0040] Supplementary to this, the inverter 4 can be arranged more compactly by being brought closer by the gearbox housing 13 and arranged within the recess 8 as much as possible. However, when the cover 15 is made to be the minimum size capable of hanging down the capacitor 5 etc., among the first cooling passages 21 integrated with the cover 15, the connection passage 21c protrudes outside the outer peripheral edge of the cover 15. For this reason, if the rear discharge passage 21b and the front supply passage 21d connected to the connection passage 21c are not inclined upward, the possibility that the first cooling passage 21 interferes with surrounding objects (for example, the motor housing 12) becomes high. Or, in order to avoid this interference, the inverter 4 has to be arranged above the recess 8. Therefore, as described above, if the portion extending in the left - right direction (in this embodiment, the rear discharge passage 21b and the front supply passage 21d) is inclined upward, such problems are solved.

[0041] Note that the configuration of the cooling unit 20 is not limited to that shown in FIG. 4 etc. For example, as shown in FIG. 5, the first cooling passage 21′ may be provided so as to connect two second cooling passages 22L and 22R in series and surround the capacitor 5 from all four sides. This first cooling passage 21′ further has an extension passage 21f extending rearward from the front discharge passage 21e and arranged on the right side of the capacitor 5, in addition to the rear supply passage 21a, the rear discharge passage 21b, the connection passage 21c, the front supply passage 21d, and the front discharge passage 21e that constitute the first cooling passage 21 of FIG. 4.

[0042] The pipe 29 is connected to the rear end of the extension path 21f, and the refrigerant that has flowed through the first cooling path 21' is discharged from the rear end of the extension path 21f to the outside of the inverter 4. In this way, if the condenser 5 is surrounded on all four sides, it is possible to eliminate the locations that cannot be cooled around the condenser 5. In this case, it is preferable that the front discharge path 21e extending in the left - right direction and connected to the extension path 21f slopes upward toward the outside in the left - right direction (away from the bulging portion 25R).

[0043] [2. Function, Effect] (1) As shown in FIGS. 1 to 3 and FIG. 7, in the above - described vehicle drive device 10, both the condenser 5 and the semiconductor module 6, which are components constituting the inverter 4, have a "hanging layout" attached to the lower surface of the cover 17. As a result, the space inside the inverter case 14 can be effectively utilized, and compared with the structure in which the condenser 5 and the semiconductor module 6 are attached to a base plate separate from the cover 15, the base plate can be omitted. In other words, since the function of the base plate can be shared by the cover 15, the number of parts can be reduced, the vertical dimension of the inverter 4 can be reduced, and space saving can be achieved. Therefore, according to the vehicle drive device 10, the inverter 4 can be compactly mounted in the limited mounting space S, and miniaturization of the vehicle drive device 10 can be realized.

[0044] In addition, the refrigerant flowing through the cooling part 20 integrated with the cover 15 can cool the components of the inverter 4 including the condenser 5 and the semiconductor module 6. In particular, since this cooling part 20 is far from the motor unit 1 which is a heat source, it is not heated by the heat of the motor unit 1, the refrigerant temperature can be kept low, and the cooling efficiency can be improved. In addition, since there is an air flow on the upper surface (the surface) of the cover 15, the cooling part 20 can be air - cooled, and this can also improve the cooling efficiency. Also, in the space surrounded by the tray part 16 and the cover 15 (that is, inside the inverter case 14), high - temperature air stays upward, but since the cooling part 20 is above, the ambient temperature inside the case can also be lowered. Therefore, according to the vehicle drive device 10, high cooling performance can be ensured.

[0045] (2) As shown in FIGS. 1 and 3, the cover 15 is provided with a convex portion 24 that is formed convexly upward from the flat plate portion 23 and houses the capacitor 5. In this way, by locally protruding the convex portion 24 that houses the capacitor 5 having a large thickness dimension from the flat plate portion 23, it is possible to secure the accommodation property of the capacitor 5 while avoiding an increase in the overall size of the cover 15. Further, the capacitor 5 can be air-cooled through the convex portion 24.

[0046] (3) According to the cooling unit 20 described above, since the second cooling passage 22 is provided directly above the position where the semiconductor module 6 is attached, the semiconductor module 6 can be efficiently cooled by the refrigerant flowing through the second cooling passage 22.

[0047] (4) Further, in the vehicle drive device 10 described above, while cooling the modules 6L and 6R with the refrigerant flowing through the second cooling passage 22, the capacitor 5 can be cooled by the refrigerant flowing through the first cooling passage 21 that surrounds the capacitor 5 from three directions or four directions. Therefore, the cooling efficiency of the inverter 4 can be improved. Also, by integrating the series-connected first cooling passage 21 with the cover 15, a hose separate from the inverter 4 can be eliminated, and the number of components can be reduced. Further, by eliminating the hose, it is not necessary to consider the bending and swinging of the hose, so the degree of freedom in layout is increased, and a more compact layout is more easily realized.

[0048] (5) In the vehicle drive device 10 described above, the inverter 4 is arranged in the mounting space S, and the capacitor 5 having the largest thickness dimension among the components of the inverter 4 is arranged in the concave portion 8, so a more compact arrangement can be realized. Further, since the portion of the first cooling passage 21 extending in the left-right direction is provided inclined, the inverter 4 can be mounted compactly without interfering with the objects around the concave portion 8.

[0049] In this embodiment, both the left and right modules 6L and 6R are disposed in the recess 8 and are respectively arranged in the front-rear direction with respect to the capacitor 5. Thus, by disposing both the capacitor 5, which is a component of the inverter 4, and the left and right modules 6L and 6R in the recess 8, the vertical dimension of the vehicle drive device 10 can be made more compact. Further, by arranging the capacitor 5 between the left and right modules 6L and 6R, each unit of the left and right motors 2L and 2R (an assembled product including the motor housing 12, the semiconductor module 6, etc., and the wiring from the motor 2) can be made common. Therefore, this contributes to simplifying the assembly work of the vehicle drive device 10 and reducing costs.

[0050] Also, in this embodiment, as shown in FIGS. 1 and 4, a cooling portion 20 is formed on the flat plate portion 23 of the cover 15 so as to overlap the convex portion 24 when viewed from a direction orthogonal to the vertical direction. Thus, by arranging the cooling portion 20 at the same height position as the convex portion 24 in the vertical direction, the dead space adjacent to the convex portion 24 in the direction orthogonal to the vertical direction can be effectively utilized. Therefore, the cooling performance of the semiconductor module 6 can be ensured while making the vertical dimension of the vehicle drive device 10 more compact.

[0051] [3. Others] Each configuration of the above-described embodiment and modification can be implemented with various modifications without departing from their gist. Also, each configuration of the embodiment and modification can be selected as needed or combined as appropriate.

[0052] For example, in the above-described first cooling passages 21 and 21', the rear discharge passage 21b and the front supply passage 21d are connected in series by the connection passage 21c. Instead of this, the rear supply passage 21a and the rear discharge passage 21b connected to the left second cooling passage 22L and the front supply passage 21d and the front discharge passage 21e connected to the right second cooling passage 22R may be connected in parallel. That is, the number of the first cooling passages through which the refrigerant flows in one direction is not limited to one, and for example, a cooling portion having two first cooling passages parallel to each other may be integrated with the cover.

[0053] For example, in the above-described embodiment, the vehicle drive device 10 in which the gearbox 3 is disposed at a position offset downward and forward in a side view with respect to the rotation axis C of the motor 2 is illustrated. However, the gearbox 3 may be offset downward and rearward. At least, by offsetting the gearbox housing 13 downward with respect to the left and right motor housings 12L and 12R, the arrangement of the inverter case 14 using the recess 8 becomes easy, and the inverter 4 can be easily arranged compactly in the mounting space S. Therefore, the same operations and effects as those of the above-described embodiment can be obtained.

[0054] The left and right modules 6L and 6R may be integrated. That is, the semiconductor module 6 may be provided as one common module for the left and right motors 2, similar to the capacitor 5. In this case, only one second cooling passage 22 may be arranged directly above one semiconductor module 6. The shape of the cover 15 described above is an example. The cover 15 only needs to have at least the cooling part integrated, and may be a flat plate shape without the convex part 24 or the bulging part 25.

Explanation of Signs

[0055] 1 Motor unit 2 Motor 3 Gearbox 4 Inverter 5 Capacitor 6 Semiconductor module 8 Recess 10 Vehicle drive device 12 Motor housing 13 Gearbox housing 14 Inverter case 15 Cover 16 Tray part 17 Cover lower surface 20 Cooling part 21 First cooling passage 21a Rear supply passage 21b Rear discharge passage (portion extending in the left - right direction) 21c Connection passage 21d Front supply passage (portion extending in the left - right direction) 21e Rear discharge path 21f Extension path 22 Second cooling passage 22L Left second cooling passage 22R Right second cooling passage 23 Flat plate part 24 Protrusion 28, 29 Pipes C Rotation axis S Mounting space

Claims

1. A motor unit having a drive motor mounted on a vehicle and a gear mechanism for transmitting the torque of the motor to each of the left and right wheels of the vehicle, An inverter disposed above the motor unit and having a capacitor for smoothing power and a semiconductor module including a plurality of switching elements, The inverter has a tray portion for housing the capacitor and the semiconductor module, and a flat cover attached to the tray portion and covering the capacitor and the semiconductor module from above, A cooling portion through which a refrigerant for cooling the inverter flows is integrated with the cover, Both the capacitor and the semiconductor module are attached to the lower surface of the cover, The cooling portion has a first cooling passage through which the refrigerant flows in one direction, and a second cooling passage formed as a space wider than the first cooling passage directly above the position where the semiconductor module is attached and through which the refrigerant flows, The motor unit has a rotating shaft extending in the left - right direction of the vehicle and left and right motors disposed apart from each other in the left - right direction for driving the left and right wheels, The gear mechanism amplifies the torque of the left and right motors and transmits it to each of the left and right wheels, The semiconductor module includes two modules used for each of the left and right motors, The second cooling passages are respectively provided directly above the positions where the two modules are attached, The first cooling passage connects the two second cooling passages in series and is provided so as to surround the capacitor in three directions or four directions, A vehicle drive device, characterized in that.

2. The cover has a flat plate portion attached to the periphery of the tray portion and provided with the cooling portion, and a convex portion formed convexly upward from the flat plate portion and housing the capacitor, The vehicle drive device according to Claim 1, characterized in that.

3. The motor unit has a gearbox sandwiched between the left and right motors and forming a recess recessed downward together with the motor housings of the left and right motors, The inverter is disposed in a mounting space including the recess and having a T - shape in a front view above the left and right motors and the gearbox, and at least the capacitor is located in the recess, A portion of the first cooling passage that extends in the left-right direction of the vehicle slopes upward toward the outside in the left-right direction within the mounting space. The vehicle drive device according to claim 1 or 2, characterized by the above.

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