Drive device

Abstract

A rotary electric machine according to the present invention has a motor housing and the motor housing has a recessed section in an upper section thereof. An inverter device has a lid-like inverter housing, electric components are disposed facing the rotary electric machine on an inner surface of the inverter housing, and the inverter housing is fixed to a rotary electric machine housing, whereby an accommodation chamber for accommodating the electric components is formed with the inverter housing and the recessed section. In the accommodation chamber, the electric components include a first electric component and a second electric component that reaches a higher temperature than the first electric component, and the first electric component and the second electric component are disposed spaced away from each other in the axial direction of the rotary electric machine.

Description

Drive unit

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

[0002] A power conversion device that supplies power to a rotating electric machine is configured by accommodating electrical components such as a power module, a capacitor module, and bus bars in a housing. JP6406443B discloses a configuration in which a power module and a capacitor module are arranged on the upper surface of a support member that has a cooling flow path, and the support member is accommodated in an electric motor housing and closed by a top plate.

[0003] In conventional technology, the need for support members to cool the power module and a top plate to cover the motor housing increases the number of parts, resulting in increased size and weight. While it is possible to omit the support members to reduce size and weight, this creates the problem that heat-generating electrical components, such as bus bars, are likely to affect other electrical components.

[0004] The present invention has been made in view of the above problems, and has an object to provide a technique for suppressing the influence of heat on electrical components.

[0005] One embodiment of the present invention is applied to a drive unit including a rotating electric machine and an inverter device mounted on top of the rotating electric machine and transmitting and receiving electric power to and from the rotating electric machine. The drive unit has a motor housing that houses the rotating electric machine, and the motor housing has a recess in its upper part. The inverter device has a lid-shaped inverter housing, and electrical components are arranged on the inner surface of the inverter housing facing the rotating electric machine. When the inverter housing is fixed to the rotating electric housing, an accommodation chamber that accommodates the electrical components is formed by the inverter housing and the recess in the motor housing. In the accommodation chamber, the electrical components include a first electrical component and a second electrical component that becomes hotter than the first electrical component, and the first electrical component and the second electrical component are arranged spaced apart in the axial direction of the rotating electric machine.

[0006] According to the present invention, in a configuration in which electrical components are arranged on the inner surface of the inverter housing and accommodated in an accommodation chamber between the inverter housing and the motor housing, by arranging the second electrical component, which becomes hot, and the first electrical component at a distance from each other, it is possible to prevent the heat from the second electrical component from being transferred to the first electrical component.

[0007] Fig. 1 is a cross-sectional view of a drive device according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of an inverter device, Fig. 3 is a perspective view of a motor housing, and Fig. 4 is a perspective view of the drive device.

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

[0009] FIG. 1 is a configuration diagram of a drive device 1 according to an embodiment of the present invention.

[0010] The drive device 1 includes a power conversion device (inverter device) 10, a motor 20, and a reducer 30. The drive device 1 is mounted on an electric vehicle, and receives power from a battery (not shown) to drive the motor 20, thereby causing the electric vehicle to run.

[0011] The motor 20 drives the electric vehicle by transmitting rotation to the drive wheels via the reduction gear 30. The motor 20 also functions as a generator that generates regenerative power when the electric vehicle decelerates. The reduction gear 30 reduces the rotation of the rotary shaft 22 of the motor 20 and transmits the reduced rotation to the drive wheels. The motor 20 and the reduction gear 30 are disposed in a motor housing 21.

[0012] The motor 20 includes an inner housing 23, a stator 24, and a rotor 25. The inner housing 23, which houses the stator 24 and the rotor 25, is fitted into the motor housing 21. A gap is formed between the motor housing 21 and the inner housing 23, and this gap serves as a coolant flow path 41. The coolant flow path 41 is formed so that coolant circulates around the outer periphery of the stator 24 of the motor 20. A rotating shaft 22 is provided at the center of rotation of the rotor 25. The rotating shaft 22 is connected to a reducer 30.

[0013] The inverter device 10 is disposed above the motor housing 21. The inverter device 10 includes an inverter housing 11 and electrical components housed in the inverter housing 11, such as a power module 12, a capacitor module 13, and a three-phase inverter-side bus bar 14.

[0014] The inverter housing 11 has a box-like shape with its outer edge extending toward the motor housing 21 and opening downward. The inverter housing 11 covers the motor housing 21 like a lid and is fixed to the motor housing 21 by bolts or the like. When the inverter housing 11 is fixed to the motor housing 21, the space defined by the inner surface of the inverter housing 11 and the upper recess 21a of the motor housing 21 forms an accommodation chamber 101 that accommodates electrical components.

[0015] In the accommodation chamber 101, the power module 12 and the capacitor module 13 are fixed to the inner surface of the inverter housing 11 and are arranged to face the motor housing 21. The inverter-side bus bar 14 is connected to the power module 12 on the inverter housing 11 side and is arranged to face the motor housing 21 at a position separated from the power module 12. The tip portion of the inverter-side bus bar 14 is connected to the motor-side bus bar 28.

[0016] A three-phase motor-side bus bar 28 extends from the upper axial end of the motor 20. The motor-side bus bar 28 is composed of an extension portion 28a that extends outward (to the right in FIG. 1 ) along the axial direction from the coil end 27 of the motor 20, and an upper extension portion 28b that extends upward from the end of the extension portion 28a.

[0017] The motor-side bus bar 28 and the inverter-side bus bar 14 are fixed by connecting portions 29. The connecting portions 29 are made up of bolts and nuts, and are fastened together with fixing holes formed in the inverter-side bus bar 14 and fixing holes formed in the upper extension portions 28b of the motor-side bus bar 28, thereby establishing electrical continuity between them.

[0018] Next, the arrangement of electrical components in the inverter device 10 configured as above will be described.

[0019] The inverter device 10 has a housing chamber 101 in which a power module 12, a capacitor module 13, and an inverter-side bus bar 14 are provided. A lower end of the inverter-side bus bar 14 is connected to a motor-side bus bar 28 by a connection portion 29.

[0020] Here, heat transfer between these electrical components provided in the housing chamber 101 of the inverter device 10 will be described.

[0021] Generally, functional electrical components such as the power module 12 and the capacitor module 13 have a set upper limit of operating temperature and a relatively low heat resistance temperature (e.g., 150°C) (hereinafter referred to as "first electrical components"). On the other hand, electrical wire components such as the inverter-side bus bar 14 and the motor-side bus bar 28 have a wide operating temperature range and a relatively high heat resistance temperature (e.g., 300°C) (hereinafter referred to as "second electrical components"). The motor-side bus bar 28 reaches a higher temperature due to heat transferred from the coil end 27 of the motor 20. Furthermore, the connection 29 connecting the inverter-side bus bar 14 and the motor-side bus bar 28 reaches a higher temperature due to contact resistance. The inverter-side bus bar 14 connects the connection 29 and the power module 12, but because the creepage distance between them is large and the bus bar is fixed within the inverter housing 11, the impact of heat on the first electrical components is small.

[0022] When the first electrical component and the second electrical component are arranged in the same space within the accommodation chamber 101, the heat generated from the second electrical component, which has a wider operating temperature range and a higher temperature, is radiated and transferred to the first electrical component, which has a lower temperature than the second electrical component.

[0023] Of the first electrical components, the power module 12 is a heat-generating component, and is therefore configured to be in direct contact with the cooling water flow path formed in the inverter housing 11 and to be constantly cooled. Of the first electrical components, the capacitor module 13 is configured not to be cooled by cooling water because the range of heat generation is small. Therefore, if a heat-generating second electrical component is placed nearby, the capacitor module 13 will receive the heat and be significantly affected by the heat.

[0024] In contrast, among the second electric components, the connection portion 29 connecting the inverter-side bus bar 14 and the motor-side bus bar 28 becomes hot during operation, and is therefore a component that is likely to transfer heat to the first electric component. As a result of the second electric component transferring heat to the first electric component, the first electric component may receive heat and approach its heat resistance temperature.

[0025] To prevent this, it is conceivable to construct the inverter housing in a box shape so that heat is not transferred to the electrical components inside the inverter device chamber, but such a construction creates new problems, such as an increase in the size and weight of the inverter device.

[0026] In this embodiment, as will be described below, the inverter device 10 is configured to prevent heat problems from occurring in the electrical components within the inverter device 10 while suppressing increases in size and weight.

[0027] Fig. 2 is a cross-sectional view of the drive device 1, with the inverter device 10 at the center. Fig. 3 is a perspective view of the accommodation chamber 101 of the motor housing 21, with the inverter device 10 removed.

[0028] 2 , the extension portion 28 a of the motor-side bus bar 28 extends axially from the coil end 27 of the motor 20 outward on the opposite side from the reducer 30. The capacitor module 13 is disposed in the accommodation chamber 101 to the left of the power module 12, i.e., at a position separated from the motor-side bus bar 28.

[0029] This results in the capacitor module 13 fixed to the inverter housing 11 and the connection portion 29 connecting the inverter side bus bar 14 and the motor side bus bar 28 being positioned at a distance in the axial direction, thereby preventing heat from the motor side bus bar 28 and the connection portion 29 from being transferred to the capacitor module 13.

[0030] Furthermore, in the drive unit 1 of this embodiment, a flat shielding wall 102 is formed on the top surface of the motor housing 21, i.e., on the bottom surface of the accommodation chamber 101, standing upward from the bottom surface. The shielding wall 102 separates the interior of the accommodation chamber 101 into an area where the first electric components (power module 12, capacitor module 13) are arranged and an area where the second electric components (motor-side bus bar 28, connection portion 29) are arranged.

[0031] More specifically, as shown in FIG. 3 , the shielding wall 102 extends in a direction perpendicular to the axial direction and is erected on the upper surface of the motor housing 21 so as to separate an area (first area 111) in which the inverter side bus bar 14, the motor side bus bar 28, and the connection portion 29 are arranged from an area (second area 112) in which the power module 12 and the capacitor module 13 are arranged.

[0032] As a result, the presence of the shielding wall 102 on the line connecting the connection portion 29 and the capacitor module 13 prevents the heat of the connection portion 29 from being directly transferred to the capacitor module 13 .

[0033] In the motor housing 21, the axial position at which the shielding wall 102 is erected is configured to be approximately the same as the axial position at which the seal member 23a provided on the inner housing 23 fitted inside the motor housing 21 is positioned.

[0034] The seal member 23a of the inner housing 23 is compressed against the inner circumferential surface of the motor housing 21 to seal the coolant flow path 41 so that the coolant does not leak. For this reason, radially outward stress acts on the motor housing 21 at the point where the seal member 23a contacts. Therefore, by forming the shielding wall 102 at the point of the motor housing 21 where stress acts, the thickness of the motor housing 21 is increased, and the rigidity of the motor housing 21 at the point where the seal member 23a contacts can be increased. This makes it possible to more reliably seal the coolant in the coolant flow path 41.

[0035] Furthermore, as shown in Fig. 3, a plurality of flat ribs 103 are formed on the top surface of the motor housing 21, i.e., the bottom surface of the accommodation chamber 101, at a position facing the capacitor module 13. A coolant flow path 41 is formed between the motor housing 21 and the inner housing 23 of the motor 20, and the ribs 103 are arranged so as to be located radially outward of the coolant flow path 41 of the motor housing 21. Note that the ribs 103 are not limited to being flat, and can have various shapes such as a plurality of protrusions or irregularities formed on the top surface of the motor housing 21.

[0036] By arranging the plurality of ribs 103 on the motor housing 21, the atmosphere around the ribs 103 is cooled by the cooling water, thereby reducing the heat transferred from the second electric component, and in particular the heat transferred to the capacitor module 13.

[0037] Next, a description will be given of the flow path of the cooling water in the drive unit 1. Fig. 4 is a perspective view of the drive unit 1 of this embodiment.

[0038] The inverter housing 11 of the drive unit 1 is provided with a cooling water inlet 45 through which cooling water flows in from the outside. The cooling water inlet 45 communicates with an inverter-side cooling water flow path (not shown) formed in the inverter housing 11. The cooling water that flows into the inverter-side cooling water flow path cools the electrical components (power module 12) of the inverter unit 10, and then flows into the housing-side flow path 43 from a motor-side cooling water inlet 43a formed at the point where the inverter housing 11 and the motor housing 21 contact each other. The housing-side flow path 43 has a communication port 44 (see FIG. 2 ) that communicates with the cooling water flow path 41 formed between the motor housing 21 and the inner housing 23 within the motor housing 21. The communication port 44 is located near the shielding wall 102.

[0039] The motor 20 is cooled by cooling water that flows in from a housing-side flow path 43 and flows into a cooling water flow path 41 via a communication port 44. The cooling water flow path 41 communicates with a cooling water outlet 42 formed in the motor housing. The cooling water that has circulated through the cooling water flow path 41 flows out from the cooling water outlet 42.

[0040] In the motor housing 21, the coolant with the lowest temperature that flows in from the inverter housing 11 through the motor-side coolant inlet 43a flows into the coolant flow path 41 through the communication port 44 located in the vicinity of the shielding wall 102, thereby lowering the temperature of the shielding wall 102. This reduces the heat transferred from the second electric component.

[0041] As described above, this embodiment relates to a drive unit 1 including a rotating electric machine (motor 20) and an inverter device 10 disposed above the motor 20 for transmitting and receiving electric power to and from the motor 20. The motor 20 includes a motor housing 21 having a recess 21a at its upper portion. The inverter device 10 includes a lid-shaped inverter housing 11. Electrical components are disposed on the inner surface of the inverter housing 11 facing the motor 20. The inverter housing 11 is fixed to the motor housing 21, whereby the inverter housing 11 and the recess 21a form an accommodation chamber 101 for accommodating the electrical components. The electrical components in the accommodation chamber 101 include a first electrical component (e.g., capacitor module 13) and a second electrical component (e.g., motor-side bus bar 28) that reaches a higher temperature than the first electrical component. The first electrical component and the second electrical component are disposed spaced apart in the axial direction of the rotating electric machine.

[0042] In this configuration, electrical components are arranged on the inner surface of the inverter housing 11 and housed in the accommodation chamber 101 between the inverter housing 11 and the motor housing 21, and by arranging the second electrical component, which becomes hot, and the first electrical component at a distance from each other, it is possible to prevent the heat from the second electrical component from being transferred to the first electrical component.

[0043] In addition, in this embodiment, a shielding wall 102 is formed in the recess 21a of the motor housing 21, separating the space within the accommodating chamber 101 into a first region 111 in which the first electrical component is arranged and a second region 112 in which the second electrical component is arranged.

[0044] In this configuration, a shielding wall 102 is formed to separate the first electrical component, which is more likely to receive heat, from the second electrical component, which is more likely to provide heat, thereby preventing the heat from the first electrical component from being directly transferred to the second electrical component.

[0045] In this embodiment, a cylindrical inner housing 23 is fitted into the motor housing 21, and a stator 24 of the motor 20 is fitted inside. A coolant flow path 41 is formed between the inner housing 23 and the motor housing 21. A seal member 23a is provided at the joint where the inner housing 23 and the motor housing 21 come into contact, and a shielding wall 102 is erected on the outer periphery of the joint of the motor housing 21.

[0046] In this configuration, by forming a shielding wall 102 at the joint where stress from the inner housing 23 is applied, the rigidity of the motor housing 21 can be increased, thereby more reliably sealing the cooling water in the cooling water flow path 41.

[0047] In addition, in this embodiment, the first electrical component is the capacitor module 13 that constitutes the inverter device 10, and a rib 103 that protrudes toward the capacitor module 13 is formed in the recess 21a at a position opposite the capacitor module 13.

[0048] In this configuration, multiple ribs 103 are arranged on the outer surface of the cooling water flow path 41 of the motor housing 21, which allows the atmosphere around the ribs 103 to be cooled, thereby reducing the heat transferred to the capacitor module 13.

[0049] In addition, in this embodiment, the second electrical component is a three-phase motor-side bus bar 28 that transfers power between the motor 20 and the inverter device 10, and the motor-side bus bar 28 extends axially outward from the shielding wall 102 in the motor 20.

[0050] In this configuration, the motor side bus bar 28 is positioned axially away from the first electrical component (capacitor module 13), thereby preventing the heat generated by the second electrical component, the motor side bus bar 28 and the connection portion 29, from being transmitted to the first electrical component.

[0051] In addition, in this embodiment, the motor housing 21 is provided with a motor-side cooling water inlet 43a through which cooling water flows in, and a cooling water flow path 41 through which the cooling water flowing in from the motor-side cooling water inlet 43a circulates around the outer periphery of the stator 24, and a communication port 44 connecting the motor-side cooling water inlet 43a and the cooling water flow path 41 is provided in a position close to the shielding wall 102.

[0052] In this configuration, in the motor housing 21, the coolant with the lowest temperature flowing in from the inverter housing 11 flows into the coolant flow path 41 through the communication port 44 located close to the shielding wall 102, thereby lowering the temperature of the shielding wall 102 and reducing the heat transferred from the second electrical component.

[0053] The above describes embodiments of the present invention and their modifications. However, the above embodiments and modifications merely illustrate some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0054] In this embodiment, a hybrid vehicle has been described in which an engine drives a generator and the vehicle runs on the driving force of a motor, but the present invention is not limited to this and can be similarly applied to a drive device of an electric vehicle that runs on the driving force of a motor.

Claims

1. A drive device including a rotating electric machine and an inverter device disposed on an upper portion of the rotating electric machine and configured to exchange electric power with the rotating electric machine, the rotating electric machine has a motor housing, the motor housing having a recess in an upper portion thereof, the inverter device has a lid-shaped inverter housing, electrical components are arranged on an inner surface of the inverter housing facing the rotating electric machine, and the inverter housing is fixed to the motor housing to form an accommodation chamber in which the electrical components are accommodated, between the inverter housing and the recess; In the storage chamber, the electrical components include a first electrical component and a second electrical component that has a higher temperature than the first electrical component; the first electrical component and the second electrical component are disposed apart from each other in an axial direction of the rotating electric machine, a shielding wall is formed in the recess of the motor housing to separate a space within the accommodation chamber into a region in which the first electric component is disposed and a region in which the second electric component is disposed. Drive unit.

2. 2. The drive device according to claim 1, The motor housing includes a cylindrical inner housing into which a stator of the rotating electric machine is fitted, A cooling water flow path is formed between the inner housing and the motor housing, and a seal member is provided at a joining portion where the inner housing and the motor housing are in contact with each other, The shielding wall is erected on an outer circumferential portion of the joint portion of the motor housing. Drive unit.

3. 2. The drive device according to claim 1, the first electric component is a capacitor module constituting the inverter device, a rib protruding toward the capacitor module is formed in the recess at a position facing the capacitor module; Drive unit.

4. 2. The drive device according to claim 1, the second electric component is a three-phase bus bar that transfers electric power between the rotating electric machine and the inverter device, The three-phase bus bar is provided in the rotating electric machine so as to extend axially outward beyond the shielding wall. Drive unit.

5. 2. The drive device according to claim 1, the motor housing includes a cooling water inlet into which cooling water flows, and a cooling water flow path through which the cooling water flowing in from the cooling water inlet circulates around an outer periphery of the rotating electric machine, A communication port that communicates the cooling water inlet and the cooling water flow path is provided at a position close to the shielding wall. Drive unit.