Drive device

Abstract

Provided is a drive device comprising: a motor for an electric vehicle; an inverter; and a case for accommodating the motor and the inverter. The drive device is configured so that, in the case, the inverter is located below the motor, and a coolant path is provided between the motor and the inverter, a coolant for cooling the motor flowing through the coolant path. The motor and the inverter are electrically connected by a bus bar one end of which is connected to each phase of the motor and the other end of which is connected to the inverter. The bus bar has: a first extension section extending from the motor in the motor axial-direction and extending in a direction of separation from the motor; a second extension section that is curved downward from the first extension part and that extends therefrom; and a third extension part that is curved from the second extension part in the axial direction of the motor and that connects to the inverter.

Description

Drive unit

[0001] The present invention relates to a drive device.

[0002] In order to reduce the size of drive devices used in electric vehicles, etc., it is necessary to house the motor and inverter in a single case. JP6178564B2 discloses an electric compressor in which the motor and inverter are housed in a single housing (case).

[0003] However, since inverters include many electronic components, their heat resistance temperature is lower than that of motors. Therefore, when a motor and inverter are housed in a single case, as in the electric compressor described in JP6178564B2, there is a risk that the inverter's heat resistance temperature will be exceeded due to heat received from the motor.

[0004] On the other hand, if the inverter is placed below the motor to reduce heat reception from the motor, there is a risk that foreign matter may easily get into the inverter from the motor. For example, if a conductive foreign matter gets into the inverter, it may cause an electrical short circuit.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a drive device that can suppress the temperature rise of the inverter and the intrusion of foreign matter into the inverter.

[0006] According to one aspect of the present invention, there is provided a drive device including a motor for an electric vehicle, an inverter, and a case that houses the motor and the inverter. In this drive device, the inverter is located below the motor within the case, and a coolant path through which a coolant for cooling the motor flows is provided between the motor and the inverter. The motor and the inverter are electrically connected by a bus bar, one end of which is connected to each phase of the motor and the other end of which is connected to the inverter. The bus bar has a first extension portion that extends from the motor in the axial direction of the motor and away from the motor, a second extension portion that bends downward from the first extension portion and extends, and a third extension portion that bends from the second extension portion in the axial direction of the motor and connects to the inverter.

[0007] Fig. 1 is a schematic diagram showing the main configuration of a drive device according to a first embodiment of the present invention. Fig. 2 is a schematic diagram showing a connection between a motor and an inverter of the drive device. Fig. 3 is a diagram showing a connection between a motor and an inverter of a drive device according to a second embodiment.

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

[0009] First Embodiment FIG. 1 is a schematic diagram showing the main configuration of a drive device 100 according to an embodiment of the present invention, and is a cross-sectional side view of the drive device 100. As shown in FIG.

[0010] 1 , the drive device 100 includes a motor 10, an inverter 20, a bus bar 30 that electrically connects the motor 10 and the inverter 20, a coolant passage 40 through which a coolant flows, and a case 50 that houses the motor 10 and the inverter 20. The drive device 100 is an electric powertrain (ePT) that is mounted on an electric vehicle and receives a supply of electric power from a battery (not shown) to drive the motor 10, thereby propelling the electric vehicle.

[0011] The motor 10 is an electric motor (drive motor) that receives power from a battery (not shown) and rotates the drive wheels of the electric vehicle via the axles. In this embodiment, the motor 10 is a three-phase motor. When the electric vehicle decelerates, the motor 10 rotates along with the drive wheels, generating regenerative power. In other words, the motor 10 is a rotating electric machine that also functions as a generator. The motor 10 is housed in a case 50 and is positioned above the inverter 20 within the case 50. The motor 10 is electrically connected to the inverter 20 via a bus bar 30.

[0012] Specifically, the motor 10 is composed of a stator 11, a rotor 12, and a rotating shaft 13 configured as a shaft member protruding from an end face of the rotor 12. The stator 11 is disposed radially outward of the rotor 12 and has a stator core 111 in which a plurality of coils are disposed, and coil ends 112 protrude from the end of the stator core 111 in the axial direction of the rotating shaft 13 (hereinafter also referred to as the axial direction). A bus bar 30 connected to the inverter 20 is connected to the coil ends 112. The rotor 12 is disposed inside the stator 11 so as to be rotatable relative to the stator 11.

[0013] The inverter 20 includes electrical components such as a power module and a capacitor, and converts DC power output by the battery into AC power and supplies it to the motor 10 to drive the motor 10. The inverter 20 also converts regenerative power of the motor 10 from AC power to DC power and supplies it to the battery to charge it. The inverter 20 is housed in a case 50 and is disposed below the motor 10 within the case 50. The inverter 20 is also electrically connected to the motor 10 by a bus bar 30.

[0014] The bus bar 30 is wiring that electrically connects the motor 10 and the inverter 20. A plurality of bus bars 30 (the number of phases of the motor) are provided, with one end connected to each phase of the motor 10 at the coil end 112 and the other end connected to the inverter 20. In detail, the bus bar 30 has a first extension portion 31 that extends from the coil end 112 of the motor 10 in the axial direction of the motor 10 and in a direction away from the motor 10, a second extension portion 32 that bends downward from the first extension portion 31 and extends, and a third extension portion 33 that bends from the second extension portion 32 in the axial direction of the motor 10 and connects to the inverter 20. That is, as shown in FIG. 1 , the bus bar 30 is formed in a so-called U-shape.

[0015] The bus bar 30 is provided with a current sensor 34 that detects the current flowing through the motor 10. The current sensor 34 is disposed directly below a coolant passage 40, which will be described later.

[0016] The bus bar 30 is covered with a bus bar cover 35 made of a resin material below the coil end 112. The bus bar cover 35 will be described in detail later.

[0017] The case 50 is made of aluminum or the like and houses the motor 10 and the inverter 20. The case 50 is configured by integrating a motor housing 51 that houses the motor 10 and an inverter housing 52 that houses the inverter 20.

[0018] The motor housing 51 comprises an inner housing 511 that houses the motor 10, an outer housing 512 that houses the inner housing 511 inside, and a cover 513 that covers the opening of the inner housing 511 in the axial direction of the motor 10. The inner housing 511 and the outer housing 512 are cylindrical, with the inner housing 511 housing the stator 11 inside, and the outer housing 512 housing the inner housing 511 inside. The inner housing 511 and the outer housing 512 have flanges 5111 and 5121, respectively, near the peripheries of the coil ends 112 of the motor 10. The inner housing 511 and the outer housing 512 are fastened together at the flanges 5111 with bolts or the like.

[0019] The inverter housing 52 is configured in a lid shape and is configured to cover the inverter 20, which is disposed outside the motor housing 51 (outer housing 512) and below the motor 10. The inverter housing 52 is fastened to the motor housing 51 (outer housing 512), so that the motor housing 51 and the inverter housing 52 are integrated to form the case 50.

[0020] The coolant path 40 is a cooling water path through which coolant that cools the motor 10 flows, but is not limited to this and may be, for example, a flow path through which cooling gas flows. The coolant path 40 is provided between the motor 10 and the inverter 20. More specifically, the coolant path 40 is formed between the inner housing 511 and the outer housing 512 of the motor housing 51. As described above, the current sensor 34 is disposed directly below the coolant path 40. The coolant path 40 is sealed by a sealing member such as an O-ring.

[0021] As described above, the drive device 100 accommodates the motor 10 and the inverter 20 in the case 50, and the inverter 20 is disposed below the motor 10 within the case 50. Because the drive device 100 accommodates the motor 10 and the inverter 20 in a single case 50, the device can be made compact.

[0022] Here, since the inverter includes many electronic components and has a lower heat resistance temperature than the motor, if the motor and inverter are housed in a single case, there is a risk that the inverter will exceed its heat resistance temperature due to heat received from the motor. In contrast, in the drive device 100 of this embodiment, the inverter 20 is disposed below the motor 10, so that heat received by the inverter 20 from the motor 10 is suppressed, and a rise in the temperature of the inverter 20 is suppressed. In other words, the inverter 20 is prevented from exceeding its heat resistance temperature.

[0023] Since inverters contain many electronic components, they require stricter impurity control than motors to prevent electrical short circuits and thus require more stringent impurity management. However, placing the inverter below the motor in the case presents a problem of increased susceptibility to contaminants from the motor into the inverter. In particular, when electrically connecting the upper motor and the lower inverter using a bus bar, a hole (opening) through which the bus bar passes must be provided at the bottom of the motor housing in the case. However, there is a risk that impurities (foreign matter) from the motor may pass through the gap in the opening and enter the inverter. Therefore, in this embodiment, as described above, the bus bar 30 electrically connecting each phase of the motor 10 to the inverter 20 is configured to have a U-shape. That is, the bus bar 30 is configured to have a first extension portion 31 extending from the motor 10 in the axial direction of the motor 10 and away from the motor 10, a second extension portion 32 bending downward from the first extension portion 31 and extending, and a third extension portion 33 bending from the second extension portion 32 in the axial direction of the motor 10 and connecting to the inverter 20. By configuring the bus bar 30 in this manner, the hole (opening) in the motor housing 51 through which the bus bar 30 passes is formed in the axial direction of the motor 10. Therefore, foreign matter is prevented from falling from the motor 10 through the passage of the bus bar 30 into the inverter 20, and the intrusion of foreign matter into the inverter 20 is suppressed. In other words, the intrusion of foreign matter into the inverter 20 can be suppressed while suppressing a temperature rise in the inverter 20.

[0024] The connection between the motor 10 and the inverter 20 in the drive device 100 will be described in detail below.

[0025] FIG. 2 is a schematic cross-sectional view showing the connection portion between the motor 10 and the inverter 20 of the drive device 100.

[0026] 2, the inverter 20 is located below the motor 10 within the case 50. This prevents the inverter 20 from increasing in temperature due to heat received from the motor 10. The motor 10 is housed in a motor housing 51 (inner housing 511, outer housing 512, cover 513), and within the case 50, the motor 10 side and the inverter 20 side form separate spaces.

[0027] As described above, the bus bar 30 of the drive device 100 has a first extension portion 31 that extends from the coil end 112 of the motor 10 in the axial direction of the motor 10 and away from the motor 10, a second extension portion 32 that bends downward and extends from the first extension portion 31, and a third extension portion 33 that bends from the second extension portion 32 in the axial direction of the motor 10 and connects to the inverter 20. By shaping the bus bar 30 in this manner, foreign matter is prevented from falling from the motor 10 through the passage of the bus bar 30 onto the inverter 20, and the intrusion of foreign matter into the inverter 20 is suppressed.

[0028] As shown in FIG. 2 , the motor housing 51 (inner housing 511, outer housing 512) includes flanges 5111, 5121 at the axial ends of the stator core 111 (where the coil ends 112 are formed). The flanges 5111, 5121 may have any shape as long as they have at least a portion extending in the vertical direction at the axial end of the stator core 111. Because the motor housing 51 includes the flanges 5111, 5121 extending in the vertical direction at the axial end of the stator core 111, foreign matter from the motor 10 located above is further prevented from entering the inverter 20. The flanges 5111, 5121 also include openings 53 that open in the axial direction of the motor 10. The openings 53 open to a space on the motor 10 side and a space on the inverter 20 side. The third extension portion 33 of the busbar 30 is bent from the second extension portion 32 in the axial direction of the motor 10 , passes through the openings 53 in the flanges 5111 and 5121 of the motor housing 51 , and is connected to the inverter 20 .

[0029] As shown in FIG. 2 , bus bars 30 connected to each phase of the motor 10 (hereinafter also referred to as three-phase bus bars) are covered by bus bar covers 35 made of resin below the coil ends 112 of the motor 10. The bus bar cover 35 covers the periphery of the bus bar 30 and has an extension portion 351 extending in the vertical direction. The extension portion 351 has a contact portion 352 that axially contacts a surface of a flange 5121 of the motor housing 51 (outer housing 512) closer to the inverter 20. The contact portion 352 contacts a portion of the flange 5121 that extends downward from the axial end of the stator core 111. Because the bus bar cover 35 is disposed in axial contact with the flange 5121 of the motor housing 51 (outer housing 512), the opening 53 connecting the space on the motor 10 side and the space on the inverter 20 side is sealed by the bus bar cover 35. This prevents foreign matter from the motor 10 from entering the inverter 20 through the opening 53. That is, the intrusion of foreign matter from the motor 10 into the inverter 20 is further suppressed. Furthermore, foreign matter from the motor 10 normally falls from the coil ends 112. However, because the busbar cover 35 is provided below the coil ends 112, the intrusion of foreign matter from the motor 10 into the inverter 20 is further suppressed. Furthermore, because the busbar cover 35 is made of a resin material with low thermal conductivity, heat transfer from the motor 10 to the inverter 20 is further suppressed, and the temperature rise of the inverter 20 is further suppressed. Note that disposing the busbar cover 35 in axial contact with the flange 5121 of the motor housing 51 (outer housing 512) also has the advantage of facilitating assembly and positioning of the busbar cover 35.

[0030] As shown in FIG. 2 , a current sensor 34 that detects the current flowing through the motor 10 is provided on the bus bar 30 between the bus bar cover 35 and the inverter 20. The current sensor 34 is provided directly below the coolant path 40 formed between the inner housing 511 and the outer housing 512. This prevents the current sensor 34 from being subjected to thermal interference from the motor 10. That is, the current sensor 34 is an electronic component, and like the inverter 20, its heat resistance temperature is lower than that of the motor 10. Therefore, in this embodiment, the coolant path 40 is provided between the motor 10 and the inverter 20, and the current sensor 34 is provided directly below the coolant path 40, thereby preventing the current sensor 34 from being subjected to thermal interference from the motor 10. This prevents the temperature of the current sensor 34 from rising and exceeding its heat resistance temperature.

[0031] According to the drive device 100 of the first embodiment, the following effects can be obtained.

[0032] In the drive device 100, the inverter 20 is located below the motor 10 within a case 50 that houses the motor 10 and the inverter 20. The bus bar 30 electrically connects each phase of the motor 10 to the inverter 20. The bus bar 30 has a first extension portion 31 that extends from the motor 10 in the axial direction of the motor 10 and away from the motor 10, a second extension portion 32 that bends downward from the first extension portion 31 and extends, and a third extension portion 33 that bends from the second extension portion 32 in the axial direction of the motor 10 and connects to the inverter 20. That is, the bus bar 30 has a U-shape. Since the inverter 20 is located below the motor 10 in this way, heat reception by the inverter 20 from the motor 10 is suppressed within the case 50, and a temperature rise in the inverter 20 is suppressed. Furthermore, by configuring the bus bar 30 in a U-shape, foreign matter is prevented from falling from the motor 10 through the passage of the bus bar 30 onto the inverter 20, and the intrusion of foreign matter into the inverter 20 is suppressed. That is, the intrusion of foreign matter into the inverter 20 can be suppressed while suppressing a temperature rise in the inverter 20.

[0033] The drive unit 100 includes a case 50 that is formed by integrating a motor housing 51 that houses the motor 10 and an inverter housing 52 that houses the inverter 20. This defines separate spaces within the case 50 for the motor 10 and the inverter 20. The drive unit 100 further includes a busbar cover 35 made of a resin material that covers the busbar 30. The busbar cover 35 has an abutment portion 352 that abuts against the surface of the flange 5121 of the motor housing 51 that is closer to the inverter 20. Because the busbar cover 35 is positioned so as to abut against the surface of the flange 5121 of the motor housing 51 that is closer to the inverter 20, the busbar cover 35 seals the opening 53 that connects the space on the motor 10 side and the space on the inverter 20 side. This prevents foreign matter from the motor 10 from entering the inverter 20 through the opening 53 that connects the space on the motor 10 side and the space on the inverter 20 side. That is, the intrusion of foreign matter from the motor 10 into the inverter 20 is further suppressed.

[0034] Furthermore, since the busbar cover 35 is made of a resin material with low thermal conductivity, heat transfer from the motor 10 to the inverter 20 is further suppressed, and the temperature rise of the inverter 20 is further suppressed.

[0035] Furthermore, since the bus bar cover 35 is disposed in contact with the flange 5121 of the motor housing 51, the assembly and positioning of the bus bar cover 35 is facilitated.

[0036] In the drive device 100, the bus bar cover 35 is disposed below the coil end 112 of the motor 10. This further prevents foreign matter from the motor 10 from entering the inverter 20.

[0037] In the drive device 100, the flanges 5111, 5121 of the motor housing 51 have portions that extend downward at least at the axial end of the stator core 111 of the motor 10. This further prevents foreign matter from the motor 10 located above from entering the inverter 20.

[0038] In the drive device 100, a current sensor 34 that detects the current flowing through the motor 10 is provided on the bus bar 30, and the current sensor 34 is disposed directly below a coolant path 40 that is provided between the motor 10 and the inverter 20. In this way, because the current sensor 34 is disposed directly below the coolant path 40, thermal interference of the current sensor 34 from the motor 10 is suppressed. This suppresses a temperature rise in the current sensor 34, and prevents the current sensor 34 from exceeding its heat resistance temperature.

[0039] 1 and 2 of this embodiment, the first extension portion 31 and the third extension portion 33 of the bus bar 30 are configured to extend horizontally in the axial direction, but the first extension portion 31 and the third extension portion 33 do not have to extend in a direction completely horizontal to the axial direction. Similarly, the second extension portion 32 is configured to extend perpendicular to the axial direction, but the second extension portion 32 does not have to extend in a direction completely perpendicular to the axial direction. In other words, the bus bar 30 only needs to be formed in a substantially U-shape.

[0040] In addition, in this embodiment, the coolant passage 40 is formed between the inner housing 511 and the outer housing 512 of the motor housing 51, but this is not necessarily limited to this. The coolant passage 40 may be provided anywhere between the motor 10 and the inverter 20.

[0041] Furthermore, as in the present embodiment, it is preferable that the drive device 100 includes a bus bar cover 35 that covers the bus bar 30, but this is not necessarily limited to this, and the drive device 100 does not necessarily have to include the bus bar cover 35. If the bus bar 30 is formed in a U-shape, it is possible to suppress foreign matter from entering the inverter 20 to some extent.

[0042] Furthermore, as in this embodiment, it is preferable to place the current sensor 34 directly below the refrigerant path 40, but this is not necessarily limited to this, and the current sensor 34 may be placed in a position other than directly below the refrigerant path 40. If the inverter 20 is located below the motor 10 and the current sensor 34 provided on the bus bar 30 connecting the motor 10 and the inverter 20 is also located below the motor 10, it is possible to suppress thermal interference from the motor 10 to some extent.

[0043] Second Embodiment A drive device 100 according to a second embodiment will be described with reference to Fig. 3. In this embodiment, the shape of the motor housing 51 is different from that of the first embodiment. Note that elements similar to those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0044] FIG. 3 is a cross-sectional view showing a connection portion between the motor 10 and the inverter 20 in the drive device 100 of the second embodiment.

[0045] As shown in FIG. 3 , in this embodiment, the bottom surface of the inner housing 511 of the motor housing 51 that houses the motor 10 has an inclined portion 5112 .

[0046] The inclined portion 5112 is located below the outside of the shaft end of the motor 10 and is inclined downward in the axial direction of the motor 10 and away from the inverter 20. Since the bottom surface of the motor housing 51 (inner housing 511) has a shape that is inclined downward in the direction away from the inverter 20, impurities (foreign matter) that fall from the motor 10 accumulate in the space A above the inclined portion 5112. In other words, even if impurities that fall from the motor 10 accumulate, they do not enter the inverter 20. Therefore, it is possible to further prevent foreign matter from entering the inverter 20.

[0047] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0048] Furthermore, although the above-described embodiments have been described as separate embodiments, they may be combined as appropriate.

Claims

1. A drive device comprising a motor for an electric vehicle, an inverter, and a case that houses the motor and the inverter, wherein the inverter is located below the motor within the case, and a refrigerant path is provided between the motor and the inverter through which a refrigerant that cools the motor flows, and the motor and the inverter are electrically connected by a bus bar, one end of which is connected to each phase of the motor and the other end of which is connected to the inverter, and the bus bar has a first extension portion that extends from the motor in the axial direction of the motor and away from the motor, a second extension portion that bends downward from the first extension portion and extends, and a third extension portion that bends from the second extension portion in the axial direction of the motor and connects to the inverter.

2. A drive device according to claim 1, further comprising a bus bar cover made of a resin material that covers the bus bar, wherein the case is formed by integrating a motor housing that houses the motor and an inverter housing that houses the inverter, the motor housing having a flange, and the bus bar cover having an abutment portion that abuts against a surface of the flange that is closer to the inverter.

3. A drive device according to claim 2, wherein the bus bar cover is disposed below a coil end of the motor.

4. A drive device according to claim 2, wherein the flange of the motor housing has a portion that extends downward at least at the axial end of the stator core of the motor, and the abutment portion of the bus bar cover abuts against this portion.

5. A drive device according to claim 2, wherein the bottom surface of the motor housing has an inclined portion that slopes downward in the axial direction of the motor and away from the inverter, below the outer side of the shaft end of the motor.

6. A drive device according to any one of claims 1 to 5, wherein the bus bar is provided with a current sensor that detects the current flowing through the motor, and the current sensor is disposed directly below the refrigerant path.

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