Electric drive unit and vehicle equipped with electric drive unit

Abstract

In this electric drive unit for a vehicle, a motor, an inverter, and a transmission are integrally provided in a housing. The motor and the transmission are disposed in the vehicle width direction. The inverter is disposed below the motor in the vehicle up-down direction and is disposed forward of the transmission in the vehicle front-rear direction.

Description

Electric drive unit and vehicle equipped with electric drive unit

[0001] The present invention relates to an electric drive unit and a vehicle equipped with the electric drive unit.

[0002] BACKGROUND ART In an electric drive device mounted on an electric vehicle, a technique for reducing the size by integrating a motor and an inverter is known.

[0003] Japanese Patent Application Laid-Open No. 2001-119810 discloses a vehicle drive device in which an inverter is integrally mounted in a space created on the upper surface of a motor.

[0004] When the motor and inverter are integrated, the inverter is more likely to absorb heat from the motor. It is also more likely to absorb heat from the transmission connected to the motor. If the inverter becomes too hot due to the heat absorbed from the motor and transmission, the electronic components with low heat resistance installed inside the inverter may be limited by their heat resistance temperature, and output may be limited to protect these components. Therefore, it is necessary to efficiently cool the inverter.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electric drive device in which a motor, an inverter, and a transmission are integrally configured, and which is capable of efficiently cooling the inverter.

[0006] According to one aspect of the present invention, the present invention is applied to an electric drive device for a vehicle in which a motor, an inverter, and a transmission are integrally provided in a housing. The motor and the transmission are arranged in the vehicle width direction. The inverter is arranged below the motor in the vehicle up-down direction and forward of the transmission in the vehicle front-rear direction.

[0007] FIG. 1 is a perspective view of the electric drive device according to this embodiment, as seen from above. FIG. 2 is a schematic view of the electric drive device according to this embodiment, as seen from the side. FIG. 3 is a perspective view of the electric drive device according to this embodiment, as seen from below. FIG. 4A is an enlarged view of the dashed line area X in FIG. 3. FIG. 4B is an enlarged view of the dashed line area Y in FIG. 3. FIG. 5 is a side view of the vicinity of the rear wheel of the vehicle according to this embodiment. FIG. 6A is an enlarged view of the dashed line area X in FIG. 3, and is an enlarged view of an electric drive device according to a modified example. FIG. 6B is an enlarged view of the dashed line area Y in FIG. 3, and is an enlarged view of an electric drive device according to a modified example.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] Fig. 1 is a perspective view of an electric drive device 1 according to this embodiment, seen from above the front side of a vehicle. Fig. 2 is a side view of the electric drive device 1.

[0010] The electric drive device 1 according to this embodiment shown in Fig. 1 is mounted on a vehicle 100 (see Fig. 5) to be described later so as to drive the rear wheels of the vehicle. The vehicle 100 is, for example, an electric automobile.

[0011] As shown in FIGS. 1 and 2, the electric drive device 1 is configured by integrating a motor 3, an inverter 4, and a transmission 5 within a housing 2.

[0012] The motor 3 includes a stator (not shown) and a rotor having a rotating shaft. The motor 3 is rotated by power supplied from the inverter 4 and functions as an electric motor that drives the drive wheels of the vehicle 100. The motor 3 also functions as a generator that is driven by the rotation of the wheels and generates (regenerates) electricity. Therefore, the motor 3 functions as a so-called motor generator (rotating electric machine) that functions as both an electric motor and a generator.

[0013] The inverter 4 includes various electronic components such as a power module, a smoothing capacitor, a noise filter, and a current sensor (not shown). The inverter 4 is electrically connected to the motor 3 and the battery, and converts DC power supplied from the battery into AC power and supplies it to the motor 3. When the vehicle is decelerating, the inverter 4 also charges the battery with regenerative power from the motor 3.

[0014] The transmission 5 is a reducer that reduces the rotation speed of the motor 3 and outputs the reduced rotation speed. The output of the transmission 5 is transmitted to the drive wheels of the vehicle 100.

[0015] Next, the detailed configuration of the housing 2 will be described. As shown in FIG. 1 , the housing 2 is divided into a motor housing section 2a that houses the motor 3, an inverter housing section 2b that houses the inverter 4, and a transmission housing section 2c that houses the transmission 5. When assembling the electric drive device 1, the motor 3, the inverter 4, and the transmission 5 are respectively housed in the housing 2 through the openings of each housing section. After that, covers or the like are fixed to each opening with bolts. In this way, the motor 3, the inverter 4, and the transmission 5 are housed integrally inside the single housing 2. The housing 2 is formed by casting a metal with high thermal conductivity (e.g., an aluminum alloy).

[0016] In this embodiment, when the housing 2 is mounted on the vehicle 100, the motor accommodating portion 2a and the transmission accommodating portion 2c are arranged side by side in the vehicle width direction A. The inverter accommodating portion 2b is arranged lower than the motor accommodating portion 2a in the vehicle up-down direction B. The inverter accommodating portion 2b is arranged forward of the transmission accommodating portion 2c in the vehicle fore-and-aft direction C. As a result, the motor 3 and the transmission 5 are arranged side by side in the vehicle width direction A. The inverter 4 is arranged lower than the motor 3 in the vehicle up-down direction B and forward of the transmission 5 in the vehicle fore-and-aft direction C.

[0017] The arrangement of the inverter accommodating portion 2b will be further described while describing the detailed configuration of the motor 3 and the transmission 5.

[0018] As shown in FIG. 2, the transmission 5 is a reduction gear having a three-shaft structure, and includes a first shaft 5a, a second shaft 5b, and a third shaft 5c.

[0019] The first shaft 5a extends toward the adjacent motor 3 and constitutes the rotation shaft of the motor 3. Alternatively, the first shaft 5a is configured as a separate member that is connected to the tip of the rotation shaft of the motor 3. This causes the first shaft 5a to rotate coaxially with the rotation shaft of the motor 3. A first gear (not shown) is also fixed to the first shaft 5a.

[0020] The second shaft 5b is disposed rearward of the first shaft 5a in the vehicle longitudinal direction C and above the first shaft 5a and the third shaft 5c in the vehicle vertical direction B. A second large-diameter gear and a second small-diameter gear are fixed to the second shaft 5b. Rotation of the first shaft 5a is transmitted to the second shaft 5b via the first gear and the second large-diameter gear that meshes with the first gear.

[0021] The third shaft 5c is disposed rearward of the second shaft 5b in the vehicle longitudinal direction C and below the first shaft 5a in the vehicle vertical direction B. A third gear that meshes with the second small-diameter gear is fixed to the third shaft 5c. Rotation of the second shaft 5b is transmitted to the third shaft 5c via the second small-diameter gear and the third gear. The third shaft 5c extends toward the rear wheels 101 (see FIG. 5) of the vehicle 100 and constitutes the axle of the rear wheels 101 (see FIG. 5). Alternatively, the third shaft 5c may be configured as a separate member that is connected to the axle of the rear wheels 101. As a result, rotation of the third shaft 5c is transmitted to the rear wheels 101, driving the rear wheels 101.

[0022] With this configuration, in a side view as shown in FIG. 2 , the line connecting the centers of the first shaft 5a, the second shaft 5b, and the third shaft 5c is generally L-shaped. Therefore, the transmission accommodating portion 2c also has a generally L-shaped shape in a side view, with a recess in the front lower portion. In other words, a large space is created in the housing 2 below the first shaft 5a of the transmission 5 and in front of the third shaft 5c. In this embodiment, the inverter accommodating portion 2b, which accommodates the inverter 4, is laid out so that part of this space fits into that space.

[0023] According to the above-described configuration, since the inverter accommodating portion 2b is located lower than the motor accommodating portion 2a, air can easily flow over the surface of the inverter accommodating portion 2b while the vehicle 100 is traveling, thereby air-cooling the inverter 4 accommodated therein. Furthermore, since the inverter accommodating portion 2b is located forward of the transmission accommodating portion 2c, air flowing during traveling flows over the surface of the inverter accommodating portion 2b before passing around the transmission accommodating portion 2c. This improves the cooling efficiency of the inverter 4.

[0024] Next, the configuration of the inverter accommodating section 2b will be described in more detail. Fig. 3 is a perspective view of the electric drive device 1 according to this embodiment, seen from below the front side of the vehicle. Fig. 4A is an enlarged view of the dashed line area X in Fig. 3. Fig. 4B is an enlarged view of the dashed line area Y in Fig. 3.

[0025] 3 , the inverter accommodating portion 2b is a part of the housing 2 and is an accommodating portion formed by a plurality of walls that constitute the housing 2. The inverter accommodating portion 2b has a front surface that extends in the vehicle up-down direction B and a bottom surface that extends rearward from the lower end of the front surface. These front and bottom surfaces can also be referred to as the front and bottom surfaces of the housing 2.

[0026] 1 and 2, a plurality of protrusions 6 are provided at corners where the front surface and the bottom surface of the inverter accommodating portion 2b are connected and spaced apart from each other along the vehicle width direction A. The protrusions 6 protrude forward and downward from the corners.

[0027] The protrusion 6 is formed as a substantially rectangular plate-like member. The rear end of the protrusion 6 is fixed to the front end portion (front edge) of the bottom surface of the inverter accommodating section 2b, and the tip is disposed so as to protrude diagonally downward. Note that the rear end of the protrusion 6 may be fixed to the lower end portion (lower edge) of the front surface instead of the front end portion (front edge) of the bottom surface.

[0028] As shown in Fig. 3, a plurality of first ribs 7 extending in the up-down direction are formed on the front surface of the inverter accommodating portion 2b. More specifically, the first ribs 7 are wall members that rise forward from the surface of the front surface of the inverter accommodating portion 2b and extend linearly in the up-down direction. Furthermore, as shown in Fig. 4A, the first ribs 7 are disposed between adjacent protrusions 6 in the vehicle width direction A in a front view. That is, the lower end of each of the first ribs 7 is located between adjacent protrusions 6 in the vehicle width direction.

[0029] Furthermore, as shown in Fig. 3, a plurality of second ribs 8 extending in the front-rear direction are formed on the bottom surface of the inverter accommodating section 2b. More specifically, the second ribs 8 are wall members that rise downward from the surface of the bottom surface of the inverter accommodating section 2b and extend linearly in the front-rear direction. As shown in Fig. 4B, the second ribs 8 are arranged to extend rearward from the position where the protrusions 6 are arranged in a bottom view. That is, the second ribs 8 extend straight from immediately behind the protrusions 6.

[0030] According to the above-described configuration, air flowing over the protrusions 6 while the vehicle 100 is traveling is redirected by the protrusions 6 and flows upward along the front surface of the inverter accommodating portion 2b. On the other hand, air passing between the protrusions 6 flows rearward along the bottom surface of the inverter accommodating portion 2b. In other words, the protrusions 6 divide the air flow into the front and bottom surfaces of the inverter accommodating portion 2b. This allows the air to flow over a wide area over the surface of the inverter accommodating portion 2b.

[0031] Furthermore, air rising along the front surface of the inverter accommodating section 2b flows between the multiple first ribs 7, and air flowing along the bottom surface of the inverter accommodating section 2b flows between the multiple second ribs 8. This rectifies the air flowing along the front and bottom surfaces, making it less likely for its flow speed to decrease.

[0032] Next, the configuration of the vehicle 100 equipped with the electric drive device 1 will be described.

[0033] Figure 5 is a side view of the vicinity of a rear wheel 101 of a vehicle 100 according to this embodiment. As shown in Figure 5, the vehicle 100 includes the electric drive device 1 described above and a battery case 9. The battery case 9 houses a battery (not shown) therein. A terminal 10 is provided on the side surface of the inverter housing 2b of the electric drive device 1, and the electric drive device 1 and the battery are electrically connected via this terminal 10.

[0034] The battery case 9 is disposed under the floor of the vehicle 100 so as to be spaced further forward of the vehicle 100 than the electric drive unit 1. The protrusion 6 provided on the housing 2 of the electric drive unit 1 is configured so that the tip of the protrusion 6 is located higher on the vehicle 100 than the bottom surface of the battery case 9 and further rearward than the rear end surface of the battery case 9.

[0035] The rear end of the bottom surface of the battery case 9 is formed as an inclined surface 9 a that slopes upward toward the rear of the vehicle 100 .

[0036] With the above configuration, air flowing along the bottom surface of the battery case 9 while the vehicle is running is more likely to flow into the inverter accommodating section 2b along the inclined surface 9a, thereby improving the cooling efficiency of the inverter 4 accommodated in the inverter accommodating section 2b.

[0037] According to the configuration described above, in the electric drive device 1 for the vehicle 100 in which the motor 3, inverter 4, and transmission 5 are integrally configured, the inverter 4 housed in the inverter housing section 2b can be efficiently cooled.

[0038] When the motor 3, inverter 4, and transmission 5 are integrally configured, the inverter 4 is more likely to absorb heat generated by the motor 3 and the transmission 5. However, in the electric drive device 1 according to this embodiment, the inverter accommodating portion 2b that accommodates the inverter 4 is provided in the housing 2 below the motor accommodating portion 2a that accommodates the motor 3. This allows air to flow more easily over the surface of the inverter accommodating portion 2b while the vehicle 100 is traveling, compared to when the inverter accommodating portion 2b is provided above the motor accommodating portion 2a. This allows the inverter 4 in the inverter accommodating portion 2b to be efficiently cooled by air cooling. Furthermore, the inverter accommodating portion 2b is provided forward of the transmission accommodating portion 2c that accommodates the transmission 5. This allows air flowing during traveling to first flow over the surface of the inverter accommodating portion 2b and then flow over the surface of the transmission accommodating portion 2c. In other words, relatively cool air that is not heated by the heat generated by the transmission accommodating portion 2c flows over the surface of the inverter accommodating portion 2b. This allows the inverter 4 accommodated therein to be efficiently cooled.

[0039] Furthermore, heat generated by the motor 3 and the transmission 5 tends to move upward in the housing 2. Therefore, with the above-described configuration in which the inverter 4 is provided below the motor 3, it is possible to suppress the heat received by the inverter 4 from the motor 3.

[0040] Furthermore, in the electric drive device 1 according to this embodiment, a plurality of protrusions 6 are arranged spaced apart from one another along the vehicle width direction A at the corner where the front surface and bottom surface of the inverter accommodating section 2b are connected.

[0041] With this configuration, the air flowing into the inverter accommodating portion 2b while the vehicle 100 is running is divided by the protrusions 6 into the front and bottom surfaces. That is, the air flows over a wider area on the surface of the inverter accommodating portion 2b. The larger the area through which the air flows, the more efficient the cooling, and therefore the inverter 4 accommodated therein can be cooled more efficiently.

[0042] In the electric drive device 1 according to this embodiment, a plurality of first ribs 7 are provided on the front surface of the inverter accommodating section 2 b along the up-down direction. Furthermore, the first ribs 7 are disposed between adjacent protrusions 6 in the vehicle width direction A in a front view.

[0043] With this configuration, while the vehicle 100 is traveling, the air that passes over the protrusion 6 and rises in front of the inverter accommodating portion 2b passes between the multiple first ribs 7. This rectifies the flow of air, making it less likely for the flow speed to decrease. The faster the flow speed of the air, the more improved the cooling efficiency, and the inverter 4 accommodated in the inverter accommodating portion 2b can be cooled more efficiently.

[0044] In the electric drive device 1 according to this embodiment, a plurality of second ribs 8 are provided on the bottom surface of the inverter accommodating section 2b along the front-rear direction. Furthermore, the second ribs 8 are arranged to extend straight from immediately behind the protrusion 6 adjacent to the protrusion 6 in the vehicle width direction A when viewed from below.

[0045] With this configuration, air that passes between the protrusions 6 and flows along the bottom surface of the inverter accommodating portion 2b while the vehicle 100 is traveling passes between the plurality of second ribs 8. This rectifies the flow of air, making it less likely for the flow velocity to decrease. Therefore, the inverter 4 accommodated in the inverter accommodating portion 2b can be cooled more efficiently, with the same effect as when the first rib 7 is provided.

[0046] Furthermore, if the housing 2 vibrates when the electric drive device 1 is operating, this may cause abnormal noise or malfunction of the device. However, by providing the first rib 7 and / or the second rib 8 in the inverter accommodating portion 2b, the rigidity of the housing 2 is improved, thereby making it possible to suppress the generation of vibrations during operation.

[0047] Furthermore, in the vehicle 100 according to this embodiment, whose rear wheels are driven by the electric drive unit 1, the tip of the protrusion 6 provided on the inverter housing 2b of the electric drive unit 1 is located above the bottom surface of the battery case 9 and behind the rear end surface of the battery case 9. Furthermore, the rear end of the bottom surface of the battery case 9 is formed as an inclined surface 9a that slopes upward as it extends rearward.

[0048] With this configuration, while the vehicle is traveling, the air flowing along the bottom surface of the battery case 9 is guided along the inclined surface 9a at the rear end of the battery case 9 to the protrusion 6 of the inverter accommodating section 2b. This makes it possible to suppress a decrease in the amount of air flowing over the surface of the inverter accommodating section 2b, even when the electric drive device 1 is mounted near the rear wheels 101 of the vehicle 100. This makes it possible to more efficiently cool the inverter 4 accommodated in the inverter accommodating section 2b.

[0049] Furthermore, because the tip of the protrusion 6 is located above the vehicle 100 relative to the bottom surface of the battery case 9, even if the vehicle 100 passes over a bump in the road, the protrusion 6 is prevented from coming into contact with the bump or the road surface. This prevents damage to the protrusion 6 and the resulting decrease in the cooling efficiency of the inverter 4.

[0050] The electric drive unit 1 according to this embodiment and the vehicle 100 equipped with the electric drive unit 1 have been described above. Next, modified examples of the electric drive unit 1 according to this embodiment will be described. Note that the modified examples described below fall within the scope of the present invention, just like this embodiment. Furthermore, detailed description of the aspects in which the same configuration as the previously described embodiment can be adopted will be omitted.

[0051] (Modification) Fig. 6A is an enlarged view of the dashed line area X in Fig. 3, which is an enlarged view of the electric drive device 1 according to a modification. Fig. 6B is an enlarged view of the dashed line area Y in Fig. 3, which is an enlarged view of the electric drive device 1 according to a modification.

[0052] 6A and 6B , the first rib 7 and the second rib 8 have a curved structure. In this modified example, the lower end of the first rib 7 is located between the protrusions 6 adjacent to each other in the vehicle width direction, and the second rib 8 extends from immediately behind the protrusions 6, similar to the previously described embodiment.

[0053] With this configuration, the area through which air flows between the first ribs 7 and the second ribs 8 is increased compared to when the first ribs 7 and the second ribs 8 have a linear structure. The larger the area through which air flows, the more efficient the cooling, and the more efficiently the inverter 4 accommodated in the inverter accommodating portion 2b can be cooled.

[0054] Although the embodiments of the present invention have been described above, the configurations described above merely show some of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

[0055] The vehicle on which the electric drive device 1 of the present embodiment is mounted is not limited to an electric automobile, but may also be, for example, a railway vehicle.

[0056] Furthermore, the electric drive unit 1 of this embodiment has been described as driving the rear wheels 101 of the vehicle 100, but it may also drive the front wheels of the vehicle 100.

[0057] Furthermore, the second shaft 5b of the transmission 5 does not necessarily have to be disposed above the first shaft 5a in the vehicle up-down direction B. If the second shaft 5b is disposed above the first shaft 5a, it is possible to maximize the space for providing the inverter accommodating section 2b. However, as long as a sufficiently large space for providing the inverter accommodating section 2b can be secured, the second shaft 5b may be disposed below the first shaft 5a.

[0058] Furthermore, as long as the inverter 4 can be cooled efficiently, the numbers of the protrusions 6, the first ribs 7, and the second ribs 8 provided on the inverter accommodating portion 2b are not particularly limited.

[0059] 1: electric drive device, 2: housing, 2a: motor housing, 2b: inverter housing, 2c: transmission housing, 3: motor, 4: inverter, 5: transmission, 5a: first shaft, 5b: second shaft, 5c: third shaft, 6: protrusion, 7: first rib, 8: second rib, 9: battery case, 9a: inclined surface, 10: terminal portion, 100: vehicle, 101: rear wheel, A: vehicle width direction, B: vehicle up-down direction, C: vehicle front-rear direction

Claims

1. An electric drive device for a vehicle in which a motor, an inverter, and a transmission are integrally provided within a housing, the motor and the transmission being arranged in the vehicle width direction, and the inverter being arranged below the motor in the vehicle up-down direction and forward of the transmission in the vehicle fore-and-aft direction.

2. An electric drive device as claimed in claim 1, wherein the transmission is a reducer with a three-shaft structure, and has: a first shaft that constitutes the rotating shaft of the motor or is connected to the rotating shaft of the motor; a second shaft that is arranged rearward of the first shaft and to which the power of the first shaft is transmitted; and a third shaft that is arranged rearward of the second shaft and below the first shaft and transmits the power of the second shaft to the drive wheels of the vehicle; and the inverter is arranged so as to be located below the first shaft and forward of the third shaft.

3. An electric drive device according to claim 2, wherein the second shaft is disposed above the first shaft and the third shaft.

4. An electric drive device as described in claim 1, wherein the housing comprises an inverter accommodating section that accommodates the inverter, the inverter accommodating section having a front surface extending in the vertical direction of the vehicle and a bottom surface extending rearward from the lower end of the front surface, and a plurality of protrusions arranged at corners where the front surface and the bottom surface are connected and spaced apart from each other along the vehicle width direction, the protrusions protruding forward and downward from the corners.

5. An electric drive device according to claim 4, wherein the inverter accommodating section has a plurality of first ribs extending in the up-down direction on the front surface, and the first ribs are arranged between the protrusions adjacent to each other in the vehicle width direction when viewed from the front.

6. An electric drive device according to claim 4, wherein the inverter accommodating section has a plurality of second ribs extending in the front-to-rear direction on the bottom surface, and the second ribs are arranged so as to extend rearward from the position where the protrusion is arranged in a bottom view.

7. An electric drive device according to claim 5 or 6, wherein the first rib and the second rib have a curved structure.

8. A vehicle comprising an electric drive device according to any one of claims 4 to 6 and a battery case housing a battery electrically connected to the electric drive device, wherein the electric drive device is configured to drive the rear wheels of the vehicle, the battery case is arranged under the floor of the vehicle so as to be spaced forward of the electric drive device, and the protrusion provided on the housing of the electric drive device has a tip located above the bottom surface of the battery case and behind the rear end surface of the battery case.

9. A vehicle according to claim 8, wherein the rear end of the bottom surface of the battery case is formed as an inclined surface that slopes upward toward the rear.

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