Power control unit mounting structure for motor unit

Abstract

To provide a power control unit attachment structure of a motor unit which does not need a space for installing a pipe of a liquid refrigerant.SOLUTION: In a power control unit attachment structure (a PCU attachment structure of a motor unit) of a MG 41, a power control unit (a PCU 43) is integrally attached to a side of a motor unit in the motor unit (MG41) mounted on an electric motor car 10 which is an electric vehicle. Fins 433 for cooling the PCU 43 are provided at the PCU 43. The fins 433 are arranged so that cooling air from the front FR of the electric vehicle flows to the rear of the electric vehicle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a power control unit mounting structure for a motor unit. [Background technology]

[0002] Some hybrid vehicles are equipped with a power generation motor that generates electricity using engine power and a drive motor that generates power for running. Because the motor generates heat when driven, cooling of the motor is necessary to ensure continuous operation (see, for example, Patent Document 1).

[0003] Furthermore, vehicles are equipped with a PCU (Power Control Unit) that incorporates electronic components such as semiconductors to drive motors (power generating motors and drive motors). The PCU must be cooled to ensure continuous operation. Such vehicles are equipped with a cooling device to cool the PCU. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-3752 Summary of the Invention [Problem to be solved by the invention]

[0005] In a vehicle, if the PCU cooling device is water-cooled, piping is required to transport a liquid refrigerant such as water to the power control unit. However, in vehicles with small interior spaces, such as light vehicles, it is difficult to secure space within the interior space to run piping for the liquid refrigerant.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a power control unit mounting structure for a motor unit that does not require space for passing piping for a liquid refrigerant. [Means for solving the problem]

[0007] In order to achieve the above object, the power control unit mounting structure of a motor unit according to the present invention is a motor unit mounted on an electric vehicle, comprising: It has a motor unit and a muffler aligned in the vehicle width direction. The power control unit is attached to the side of the motor unit. the motor unit, the muffler, and the power control unit are arranged side by side in the vehicle width direction, and the motor unit is located between the muffler and the power control unit; The power control unit is provided with fins for cooling the power control unit, and the fins are arranged so that cooling air below the electric vehicle flows toward the rear of the electric vehicle.

[0008] According to this configuration, the power control unit can be cooled using the cooling air below the electric vehicle, which eliminates the need for piping compared to when a liquid is used as a cooling medium.

[0009] In addition, in the power control unit mounting structure for a motor unit according to the present invention, the height of the fins of the power control unit is equal to or less than the height of the drive shaft.

[0010] According to this configuration, by arranging the fins of the power control unit at a low position on the vehicle, the fins can be more easily exposed to the cooling air caused by the vehicle moving, thereby improving cooling performance.

[0011] In addition, in the motor unit and power control unit mounting structure according to the present invention, a heat source is provided on the side of the motor unit, and the power control unit is provided on the opposite side of the motor unit from the heat source.

[0012] According to this configuration, it is possible to suppress the heat received by the power control unit from the heat source, thereby improving the cooling performance. [Effects of the Invention]

[0013] According to the present invention, in the power control unit mounting structure for the motor unit, the power control unit can be cooled using the cooling air from below the vehicle, so no space is required to pass piping for the liquid refrigerant. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic bottom view showing a part of an electric vehicle. [Figure 2] FIG. 2 is a side view of the lower part on the vehicle rear side of the electric vehicle. [Figure 3] FIG. 3 is a perspective view of the electric vehicle from the rear side. [Figure 4] FIG. 4 is a front view of the motor unit, PCU, and transaxle of the electric vehicle. [Figure 5] FIG. 5 is a front view of the PCU and transaxle shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of the PCU shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of an electric vehicle will be described with reference to FIGS. 1 to 6. In this specification, components according to the embodiment and their descriptions may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may also be identified by names different from those in this specification. Furthermore, the components may also be described using expressions different from those in this specification.

[0016] 1 is a schematic bottom view showing a portion of an electric vehicle 10. In this embodiment, the electric vehicle (electric vehicle) 10 is a hybrid vehicle (HV). Note that the electric vehicle 10 may also be a plug-in hybrid vehicle (PHEV), an electric vehicle (EV), a fuel cell vehicle (FCV), or any other type of vehicle that uses electricity for driving force.

[0017] As shown in the drawings, for convenience, the present specification defines an X-axis, a Y-axis, and a Z-axis. The X-axis, the Y-axis, and the Z-axis are perpendicular to one another. The X-axis is set along the vehicle width direction. The Y-axis is set along the front-rear direction. The Z-axis is set along the vertical direction.

[0018] Furthermore, in this specification, the X direction (vehicle width direction), Y direction (front-rear direction), and Z direction (vertical direction) are defined. The X direction is a direction along the X axis and includes the +X direction (rightward) indicated by the X axis arrow and the −X direction (leftward) opposite to the X axis arrow. The Y direction is a direction along the Y axis and includes the +Y direction (forward) indicated by the Y axis arrow and the −Y direction (rearward) opposite to the Y axis arrow. The Z direction is a direction along the Z axis and includes the +Z direction (upward) indicated by the Z axis arrow and the −Z direction (downward) opposite to the Z axis arrow.

[0019] The electric vehicle 10 includes a vehicle body 11, a pair of rear wheels 12, a rear suspension 13, a pair of drive shafts 14, an E-Axle 15, a fuel tank 16, and an exhaust pipe 17. The electric vehicle 10 further includes a front wheel, an engine, a battery, and various other components.

[0020] The vehicle body 11 includes, for example, a chassis and a floor panel.

[0021] The rear wheel 12, rear suspension 13, drive shaft 14, E-Axle 15, fuel tank 16, exhaust pipe 17, front wheel, engine, and battery are directly or indirectly supported on a vehicle body 11. The engine is, for example, a gasoline engine. The battery is, for example, a battery pack made up of a combination of multiple secondary batteries such as lithium-ion batteries.

[0022] The rear suspension 13 is a De Dion suspension or a torsion beam suspension. However, the rear suspension 13 is not limited to these examples. The rear suspension 13 has a pair of trailing arms 31 and an intermediate beam 32. The intermediate beam 32 may also be called a torsion beam.

[0023] The pair of trailing arms 31 are spaced apart from each other in the vehicle width direction. The trailing arms 31 extend approximately in the front-to-rear direction. Each of the pair of trailing arms 31 is attached to the corresponding rear wheel 12 and the corresponding side member. Note that the trailing arms 31 may also be attached to other parts of the vehicle body 11.

[0024] A pair of rear wheels 12 are rotatably mounted on rear ends 31 a of corresponding trailing arms 31 .

[0025] The trailing arm 31 is suspended from the vehicle body 11 via a spring. The rear suspension 13 can absorb vibrations acting on the vehicle body 11 in the vertical direction by means of the spring.

[0026] The intermediate beam 32 connects the pair of trailing arms 31. The intermediate beam 32 is attached to the trailing arm 31 midway between the two ends of the trailing arm 31. The intermediate beam 32 extends substantially in the vehicle width direction.

[0027] The exhaust pipe 17 extends approximately in the front-rear direction, and discharges exhaust gas from the cylinders of the engine to the outside from the rear end of the electric vehicle 10. The exhaust pipe 17 has a muffler 51.

[0028] The muffler 51 is formed in a box shape and reduces exhaust noise. The muffler 51 is aligned with the MG 41 (described later) in the vehicle width direction. In this embodiment, the muffler 51 is spaced from the MG 41 to the left. Therefore, the MG 41 is located between the PCU 43 and the muffler 51.

[0029] The pair of drive shafts 14 are located rearward of the intermediate beam 32. The pair of drive shafts 14 are spaced rearward from the intermediate beam 32. Each of the pair of drive shafts 14 extends approximately in the vehicle width direction and is connected to the corresponding rear wheel 12. The drive shaft 14 rotates approximately integrally with the rear wheel 12. Therefore, the drive shaft 14 can drive the rear wheel 12.

[0030] The E-Axle 15 has a motor generator (MG) 41, a transaxle (TA) 42, and a power control unit (PCU) 43. Note that the E-Axle 15 may have other components.

[0031] The MG 41 is located rearward of the intermediate beam 32 and rearward of the drive shaft 14. The MG 41 is spaced rearward from the drive shaft 14 and the intermediate beam 32. Note that a portion of the MG 41 may be located at the same position as the drive shaft 14 in the front-rear direction.

[0032] The MG 41 can function as both an electric motor and a generator. The MG 41 is, for example, a permanent magnet synchronous motor. However, the MG 41 is not limited to this example. The MG 41 includes a rotor 45. The MG 41 also includes a stator and other components.

[0033] The rotor 45 includes, for example, a permanent magnet and an output shaft. The MG 41 rotates the rotor 45 around a central axis Ax1. The central axis Ax1 extends substantially in the front-to-rear direction. The central axis Ax1 is the central axis of rotation of the rotor 45 and also the central axis of the output shaft of the rotor 45. Note that the central axis Ax1 may be slightly different from the central axis of the output shaft.

[0034] The central axis Ax1 of rotation of the rotor 45 extends in a direction intersecting with the central axis Ax2 of rotation of the drive shaft 14. The central axis Ax2 is the central axis of rotation of the drive shaft 14 and is also the central axis of the drive shaft 14. Note that the central axis Ax2 may be slightly different from the central axis of the drive shaft 14.

[0035] The drive shaft 14 has a rotational center axis Ax2 extending approximately in the vehicle width direction. In this embodiment, the rotor 45 has a rotational center axis Ax1 extending in a direction perpendicular to the rotational center axis Ax2 of the drive shaft 14.

[0036] The TA 42 includes a differential gear (diff) 46. The TA 42 may further include a transmission and other components. The differential 46 transmits rotation of the rotor 45 to the drive shaft 14. A plurality of gears included in the differential 46 or other components of the TA 42 convert the rotation of the rotor 45 about the central axis Ax1 into rotation of the drive shaft 14 about the central axis Ax2.

[0037] The PCU 43 is attached to, for example, the end surface of the MG 41 in the right direction. Therefore, the PCU 43 is aligned with the MG 41 in the vehicle width direction. However, the position of the PCU 43 is not limited to this example. The PCU 43 controls the driving of the MG 41. For example, the PCU 43 has an inverter.

[0038] When the electric vehicle 10 is traveling, the DC current output from the battery is converted to AC current by the inverter, and the AC current is supplied to the MG 41. This causes the MG 41 to perform power running, generating power. For example, when the remaining battery capacity falls below a predetermined value, the MG 41 may perform power generation operation while the engine is running.

[0039] Furthermore, when the electric vehicle 10 decelerates, the MG 41 operates in a regenerative manner, and the power transmitted from the rear wheels 12 to the MG 41 is converted into AC power. At this time, the MG 41 acts as a resistor in the driving system, and this resistance acts as a braking force (regenerative braking force) that brakes the electric vehicle 10. At this time, in the PCU 43, the AC power supplied from the MG 41 to the inverter is converted into DC power by the inverter. The DC power is then supplied to the battery, thereby charging the battery.

[0040] The fuel tank 16 stores a fuel such as gasoline. If the electric vehicle 10 is an electric vehicle, a battery is disposed in front of the intermediate beam 32 instead of the fuel tank 16. If the electric vehicle 10 is a fuel cell vehicle, the fuel tank 16 stores hydrogen.

[0041] Fig. 2 is a side view of the lower part at the rear side of the electric vehicle. Fig. 3 is a perspective view of the rear side of the electric vehicle. Fig. 4 is a front view of MG41, PCU 43, and TA 42, which are motor units of the electric vehicle. Fig. 5 is a front view of PCU 43 and TA 42 shown in Fig. 4. Fig. 6 is a cross-sectional view of PCU 43 shown in Fig. 4.

[0042] The mounting structure for the power control unit (PCU 43) of the motor unit (MG41) according to the present invention is mounted, for example, at the rear of the electric vehicle 10 in the longitudinal direction.

[0043] The MG 41, TA 42, and PCU 43 according to this embodiment are unitized and integrated by joining their respective housings 411, 421, and 431 (see FIG. 1). More specifically, the housing 411 of the MG 41 and the housing 421 of the TA 42 are joined, and the housing 411 of the MG 41 and the housing 431 of the PCU 43 are joined. In other words, the PCU 43 is integrally attached to the side of the MG 41. Note that the electric vehicle 10 according to this embodiment has been described as one in which the MG 41, TA 42, and PCU 43 are integrated. However, the electric vehicle 10 according to this embodiment is not limited to this, and the MG 41 and the PCU 43 may be integrated.

[0044] The exhaust pipe 17 is a heat source because it discharges exhaust gas from the engine to the outside of the vehicle. In the electric vehicle 10 according to this embodiment, the PCU 43, the MG 41, and the exhaust pipe 17 are arranged side by side in the vehicle width direction, as shown in Figs. 1 and 3 .

[0045] PCU 43 is disposed on the opposite side of exhaust pipe 17, which is a heat source, across MG 41 in the vehicle width direction. In other words, PCU 43 is disposed on the opposite side of exhaust pipe 17, which is a heat source, across MG 41. Therefore, PCU 43 is disposed away from exhaust pipe 17, which is a heat source, and therefore, reception of heat from the heat source can be suppressed.

[0046] 4, the PCU 43 is attached to the MG 41 so that the height of the fins 433 of the PCU 43 is approximately the same as the height of the drive shaft 14 in the vertical direction. That is, in the electric vehicle 10 according to this embodiment, the height of the fins 433 of the PCU 43 is equal to or less than the height of the drive shaft 14. Furthermore, the arrangement of the fins 433 relative to the drive shaft 14 in the vertical direction is not limited to the above, and the fins 433 of the PCU 43 may be arranged below the drive shaft 14 in the vertical direction.

[0047] As shown in FIG. 3, the PCU 43 is attached to the MG 41 so as to be exposed outside the vehicle, and has a housing 431 shown in FIGS. 4 and 5. The housing 431 has, for example, a wall 432 that is perpendicular to the vehicle width direction and has an outer surface 432f along the front-rear direction (see FIG. 3). The wall 432 has fins 433 for cooling the PCU 43. As shown in FIGS. 4 and 5, the fins 433 have protrusions 433a that protrude outward from the outer surface 432f of the wall 432, and recesses 433b that are recessed toward the inside of the housing 431 relative to the protrusions 433a. The protrusions 433a and the recesses 433b are each formed, for example, in a linear shape along the front-rear direction. A plurality of such protrusions 433a and recesses 433b are provided on the wall 432, and the protrusions 433a and the recesses 433b are arranged alternately in the vertical direction.

[0048] When the vehicle is traveling, cooling air is generated that passes under the vehicle body 11 LO of the electric vehicle 10. The cooling air flows in the directions of arrows F1, F2, F3, and F4 (i.e., from the front to the rear in the longitudinal direction of the vehicle). Between arrows F3 and F4, the cooling air flows along each of the recesses 433b of the fins 433. Therefore, the PCU 43 is cooled by the cooling air that flows from the front to the rear in the longitudinal direction of the vehicle by the fins 433.

[0049] As shown in Fig. 6, the PCU 43 includes a substrate 434, a power semiconductor (a so-called insulated gate bipolar transistor) 435, and a capacitor 436. The substrate 434, the power semiconductor 435, and the capacitor 436 are disposed in an internal space 431s located inside a housing 431 of the PCU 43. The power semiconductor 435 is attached to the substrate 434 and disposed opposite the rear surface of the fin 433 in the vehicle width direction, with the internal space 431s of the housing 431 interposed therebetween. In other words, the fin 433 and the power semiconductor 435 are disposed so as to overlap with each other when viewed from the vehicle width direction with the internal space 431s interposed therebetween. Therefore, when the electric vehicle 10 is traveling, the power semiconductor 435 is cooled by cooling air generated by the traveling.

[0050] As described above, in the PCU mounting structure for the drive motor (motor unit) 41 according to this embodiment, the PCU 43 is provided with fins 433 for cooling the PCU 43, and the fins 433 are arranged so that cooling air below the body 11 of the electric vehicle 10 flows from front to rear in the longitudinal direction of the electric vehicle 10. Therefore, the PCU 43 can be cooled using the cooling air below the body 11 of the electric vehicle 10, which eliminates the need for piping compared to when a liquid is used as a cooling medium. As a result, piping for circulating the liquid as a cooling medium is no longer necessary, which reduces the manufacturing cost of the electric vehicle 10.

[0051] Furthermore, in the PCU mounting structure for the MG41 according to this embodiment, the PCU 43 is integrally mounted on the side of the MG41 in the vehicle width direction, for example. Therefore, compared to a vehicle in which the PCU and the drive motor are provided separately and a space is provided between the PCU and the drive motor, the space in which components are arranged can be made smaller by the space provided. As a result, the space in which components are arranged can be effectively used in vehicles with limited mounting space, such as light vehicles.

[0052] Furthermore, in the PCU mounting structure for MG41 according to this embodiment, the height of the fins 433 of the PCU 43 is equal to or less than the height of the drive shaft 14. Therefore, by disposing the PCU 43 at a low position in the vertical direction of the electric vehicle 10, the PCU 43 can be more easily exposed to the cooling air caused by the movement of the electric vehicle 10, thereby improving the cooling performance of the PCU 43.

[0053] Furthermore, in the PCU mounting structure for MG 41 according to this embodiment, a heat source (muffler 51 in this embodiment) is provided on the side of MG 41, and PCU 43 is provided on the opposite side of the heat source across MG 41. This makes it possible to suppress heat reception by PCU 43 from the heat source, thereby improving cooling performance.

[0054] Furthermore, in the PCU mounting structure for MG41 according to this embodiment, when viewed from the vehicle width direction with internal space 431s interposed therebetween, fins 433 and power semiconductors 435 are arranged so as to overlap. Therefore, when electric vehicle 10 is running, power semiconductors 435 are cooled by cooling air generated by the running. On the other hand, in a vehicle in which other components are arranged between the fins and the power semiconductors, the air in the internal space cooled by the fins is heated by the other components, and cooling of the power semiconductors by the air in the internal space cooled by the fins is hindered.

[0055] In addition, in the PCU mounting structure for the MG 41 according to this embodiment, the PCU 43, the MG 41, and the muffler 51 are arranged side by side in the vehicle width direction. Therefore, in vehicles with limited mounting space, such as light vehicles, the mounting space can be effectively utilized.

[0056] Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, this embodiment is included within the scope and spirit of the invention, and is also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0057] 10...electric vehicle (electric vehicle), 14...drive shaft, 17...exhaust pipe (heat source), 41...MG (motor unit), 43...PCU (power control unit), 433...fin

Claims

1. A motor unit mounted on an electric vehicle, a muffler arranged in the vehicle width direction with the motor unit; A power control unit is integrally attached to the side of the motor unit, the motor unit, the muffler, and the power control unit are arranged side by side in the vehicle width direction, the motor unit is located between the muffler and the power control unit, the power control unit is provided with fins for cooling the power control unit, The fins are arranged so that cooling air from the front of the electric vehicle flows to the rear of the electric vehicle. A power control unit mounting structure for a motor unit.

2. The height of the fins of the power control unit is equal to or less than the height of the drive shaft.

2. The power control unit mounting structure for a motor unit according to claim 1.

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