Motor device

Abstract

A motor device (31) includes a motor (40), a first substrate (51), and a second substrate (52). The motor has a motor housing (41) and an end wall (42) attached to an axial end portion of the motor housing. The first substrate has low heat generation elements (61A, 61B) and is disposed so as to face a part of the end wall in the axial direction of the motor. The second substrate has high heat generating elements (75A, 75B, 84A, 84B, 81A1, 81B1), and is disposed on a side opposite to the end wall with respect to the first substrate in the axial direction of the motor. The second substrate has a first portion (52A) facing the first substrate and a second portion (52B) facing the end wall. The thermal resistance between the second portion and the end wall is smaller than the thermal resistance between the first substrate and the end wall.

Description

Technical Field

[0001] The present disclosure relates to a motor arrangement. Background Art

[0002] In the past, there was a motor device in which a motor and a control device were integrally provided. For example, the motor device of Patent Document 1 includes a motor and an ECU. The ECU is mounted on a heat sink, which is provided at the axial end of the motor. The ECU includes a connector unit, a main substrate, a sub-substrate, and a connecting component. The connector unit includes a connector for connecting to the outside. The connector unit is installed at a distance in the axial direction relative to the heat sink. The main substrate is fixed to the axial end face of the heat sink. The sub-substrate is fixed to the connector unit. The main substrate and the sub-substrate face each other in the axial direction. The main substrate and the sub-substrate are connected to each other via the connecting component.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-144197

[0004] The motor device of Patent Document 1 has the following concerns: For example, the volume of the heat sink must be ensured according to the amount of heat generated by the electronic components mounted on the substrate. This may increase the size of the motor device, particularly the axial dimension. Summary of the Invention

[0005] A motor device according to one embodiment of the present disclosure includes a motor, a first substrate, and a second substrate. The motor includes a metal motor housing and a metal end wall mounted on an axial end of the motor housing. The first substrate includes a low-heating element and is arranged to face a portion of the end wall in the axial direction of the motor, and is configured to control the power supply to the motor. The second substrate includes a high-heating element that generates more heat than the low-heating element and is arranged on the opposite side of the end wall relative to the first substrate in the axial direction of the motor, and is configured to supply power to the motor through control based on the first substrate. The second substrate includes a first portion facing the first substrate and a second portion facing the end wall. The thermal resistance between the second portion and the end wall is smaller than the thermal resistance between the first substrate and the end wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a structural diagram of a steering mechanism according to one embodiment of a motor device.

[0007] Figure 2 yes Figure 1 Exploded perspective view of the motor unit.

[0008] Figure 3 Yes Figure 2 A top view of the first surface of the control substrate.

[0009] Figure 4 Yes Figure 2 A bottom view of the second surface of the control substrate.

[0010] Figure 5 Yes Figure 2 A top view of the first surface of the power substrate.

[0011] Figure 6 Yes Figure 2 A bottom view of the second surface of the power substrate.

[0012] Figure 7 Yes Figure 1 A sectional view of the main parts of the motor device. DETAILED DESCRIPTION

[0013] A motor device according to one embodiment will be described. The motor device is mounted on a steering system of a vehicle, for example.

[0014] like Figure 1 As shown, the steering device of the vehicle includes a steering mechanism 11. The steering mechanism 11 is a mechanism portion that steers steerable wheels 12 of the vehicle according to the steering operation of the steering wheel.

[0015] The steering mechanism 11 includes a pinion shaft 21, a steering shaft 22, and a housing 23. The housing 23 rotatably supports the pinion shaft 21. Furthermore, the housing 23 accommodates the steering shaft 22 for axial reciprocation. The pinion shaft 21 is positioned to intersect the steering shaft 22. The pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 22a of the steering shaft 22. Both ends of the steering shaft 22 are connected to the steered wheels 12 via rack ends 24 and tie rods 25.

[0016] The steering system is a steer-by-wire steering system or an electric power steering system. In the case of a steer-by-wire steering system, the pinion shaft 21 is not mechanically connected to the steering wheel. In the case of an electric power steering system, the pinion shaft 21 is mechanically connected to the steering wheel via the steering shaft.

[0017] The steering mechanism 11 includes a motor device 31, a transmission mechanism 32, and a conversion mechanism 33. The motor device 31 is a source of steering force applied to the steering shaft 22. The steering force is a force used to steer the steering wheel 12. The transmission mechanism 32 is, for example, a belt drive mechanism. The transmission mechanism 32 transmits the rotation of the motor 31 to the conversion mechanism 33. The conversion mechanism 33 is, for example, a ball screw mechanism. The conversion mechanism 33 converts the rotation transmitted via the transmission mechanism 32 into axial movement of the steering shaft 22. The steering angle θ of the steering wheel 12 is changed by axial movement of the steering shaft 22. wThe steering shaft 22 is driven by the motor device 31 .

[0018] If the steering system is a steer-by-wire steering system, the motor device 31 functions as a steering motor. The steering motor generates a steering force, which is a force used to steer the steered wheels 12. If the steering system is an electric power steering system, the motor device 31 functions as an assist motor. The assist motor generates an assist force, which is a force used to assist in steering wheel operation.

[0019] <Structure of Motor Device 31>

[0020] Next, the structure of the motor device 31 will be described.

[0021] like Figure 2 As shown, the motor device 31 includes a motor 40 and a control device 50. The motor 40 is, for example, a three-phase brushless motor. The motor 40 has, for example, two winding systems. The control device 50 is mounted at an axial end of the motor 40. The control device 50 independently controls the power supply to the two winding systems.

[0022] The control device 50 includes a control substrate 51 , a power substrate 52 , a connector assembly 53 , and a cover 53 .

[0023] The control substrate 51 has electronic components for controlling the power supply to the motor 40. The power substrate 52 has electronic components for supplying power to the motor 40 under the control of the control substrate 51. The motor 40 has a substrate housing portion 40A at the axial end thereof. The control substrate 51 is housed inside the substrate housing portion 40A. The power substrate 52 is mounted on the axial end of the motor 40 so as to cover the control substrate 51. In the axial direction of the motor 40, the power substrate 52 is arranged at a position farther away from the motor 40 than the control substrate 51. The control substrate 51 is the first substrate of the motor device 31. The power substrate 52 is the second substrate of the motor device 31.

[0024] The connector assembly 53 is made of synthetic resin. The connector assembly 53 has a first power connector 53A and a second power connector 53B. The first power connector 53A extends in the opposite direction of the motor 40 and opens in the opposite direction of the motor 40. The first power connector 53A has a power terminal and a ground terminal. A power plug as a combination object is fitted into the first power connector 53A. The power plug is provided at the first end of the power cord. The second end of the power cord is connected to a DC power source such as a vehicle-mounted battery. The power of the DC power source is supplied to the control board 51 and the power board 52 via the power terminal and the ground terminal. The second power connector 53B has the same structure as the first power connector 53A. The DC power source is equivalent to an external power source.

[0025] The connector assembly 53 includes a first signal connector 53C and a second signal connector 53D. The first signal connector 53C extends in the direction opposite to the motor 40. The first signal connector 53C has a signal terminal. A signal plug, which is a component of the first signal connector 53C, is engaged with the first signal connector 53C. The signal plug is provided at the first end of the signal line. The second end of the signal line is connected to the vehicle control device. The control board 51 and the vehicle control device exchange signals via the signal terminal. The second signal connector 53D has the same structure as the first signal connector 53C.

[0026] The cover 54 is made of synthetic resin. It is a box-shaped body that opens toward the motor 40. The end wall of the cover 54 has a fitting hole 54A. The outer peripheral portion of the connector assembly 53 fits into the fitting hole 54A. The connectors (53A, 53B, 53C, 54C) of the connector assembly 53 pass through the fitting hole 54A and protrude outward from the end wall of the cover 54. The cover 54 is attached to the axial end of the motor 40. Together with the connector assembly 53, the cover 54 covers the end of the motor 40.

[0027] <Control Board 51>

[0028] like Figure 3 As shown, the control substrate 51 is, for example, a rectangular flat plate. The control substrate 51 has a first surface and a second surface located on opposite sides of each other. The first surface is the surface of the control substrate 51 located opposite the power substrate 52 when the motor unit 31 is assembled. The second surface is the surface of the control substrate 51 facing the power substrate 52 when the motor unit 31 is assembled.

[0029] The first surface of the control board 51 includes a first microcomputer 61A and a second microcomputer 61B. The first microcomputer 61A and the second microcomputer 61B are arranged so as to be line-symmetrical with respect to a first center line O1. The first center line O1 is a straight line passing through the center of the control board 51 when viewed from a direction perpendicular to the control board 51. The first surface includes a first inter-board connector 62A and a second inter-board connector 62B. The first inter-board connector 62A and the second inter-board connector 62B are arranged so as to be line-symmetrical with respect to the first center line O1.

[0030] like Figure 4As shown, the second surface of the control substrate 51 includes a first ground connection member 63A and a second ground connection member 63B. The first ground connection member 63A and the second ground connection member 63B are arranged symmetrically with respect to the first center line O1. The first ground connection member 63A is arranged, for example, at a position corresponding to or near the first inter-substrate connector 62A. The second ground connection member 63B is arranged, for example, at a position corresponding to or near the second inter-substrate connector 62B. The first ground connection member 63A and the second ground connection member 63B are each elastic metal member and exhibit elasticity in a direction perpendicular to the control substrate 51. The metal is, for example, copper and is electrically conductive.

[0031] <Power substrate 52>

[0032] like Figure 5 As shown, the power substrate 52 is, for example, in the form of a flat plate. The power substrate 52 has a first surface and a second surface located on opposite sides of each other. The first surface is the surface of the power substrate 52 located opposite the control substrate 51 when the motor unit 31 is assembled. The second surface is the surface of the power substrate 52 facing the control substrate 51 when the motor unit 31 is assembled.

[0033] The first surface of the power substrate 52 includes a first ripple capacitor 71A and a second ripple capacitor 71B. The first ripple capacitor 71A and the second ripple capacitor 71B are arranged line-symmetrically with respect to a second center line O2. The second center line O2 is a straight line that passes through the center of the power substrate 52 when viewed from a direction perpendicular to the power substrate 52. When viewed from a direction perpendicular to the power substrate 52, the second center line O2 coincides with the first center line O1 of the control substrate 51.

[0034] The first surface of the power substrate 52 includes a first power supply filter 72A and a second power supply filter 72B. The first power supply filter 72A and the second power supply filter 72B are arranged line-symmetrically with respect to the second center line O2. The first power supply filter 72A and the second power supply filter 72B each include a capacitor and a coil.

[0035] The first surface of the power substrate 52 includes a first power terminal connection portion 73A and a second power terminal connection portion 73B. The first power terminal connection portion 73A and the second power terminal connection portion 73B are arranged line-symmetrically with respect to the second center line O2. The first power terminal connection portion 73A is the portion of the power substrate 52 that connects the power terminal of the first power connector 53A to the ground terminal. The second power terminal connection portion 73B is the portion of the power substrate 52 that connects the power terminal of the second power connector 53B to the ground terminal.

[0036] The first surface of the power substrate 52 includes a first signal terminal connection portion 74A and a second signal terminal connection portion 74B. The first signal terminal connection portion 74A and the second signal terminal connection portion 74B are arranged line-symmetrically with respect to the second center line O2. The first signal terminal connection portion 74A is the portion of the power substrate 52 to which the signal terminals of the first signal connector 53C are connected. The second power signal connection portion 74B is the portion of the power substrate 52 to which the signal terminals of the second signal connector 5D are connected.

[0037] The first surface of the power substrate 52 includes a first power supply circuit 75A and a second power supply circuit 75B. The first power supply circuit 75A and the second power supply circuit 75B are arranged so as to be line-symmetrical with respect to the second center line O2. The first power supply circuit 75A and the second power supply circuit 75B are each chip-type integrated circuits. The first power supply circuit 75A converts the voltage of the vehicle's DC power supply to a voltage suitable for the operation of the electrical circuits of the first system, including the first microcomputer 61A. The second power supply circuit 75B converts the voltage of the vehicle's DC power supply to a voltage suitable for the operation of the electrical circuits of the second system, including the second microcomputer 61B. This conversion includes a process of lowering the voltage of the vehicle's DC power supply.

[0038] like Figure 6 As shown, the second surface of the power substrate 52 includes a first inverter circuit 81A and a second inverter circuit 81B. The first inverter circuit 81A and the second inverter circuit 81B are arranged symmetrically with respect to the second center line O2. The first inverter circuit 81A and the second inverter circuit 81B each include a plurality of switching elements. The switching elements are, for example, FETs (Field Effect Transistors).

[0039] The switching elements of the first inverter circuit 81A perform switching operations to convert DC power supplied from the DC power supply into three-phase AC power. The AC power generated by the first inverter circuit 81A is supplied to the first winding group of the motor 40 via a power supply path such as a bus bar. The switching elements of the second inverter circuit 81B perform switching operations to convert DC power supplied from the DC power supply into three-phase AC power. The AC power generated by the second inverter circuit 81B is supplied to the second winding group of the motor 40 via a power supply path such as a bus bar.

[0040] The second surface of the power substrate 52 includes a first phase disconnect relay group 82A and a second phase disconnect relay group 82B. The first phase disconnect relay group 82A and the second phase disconnect relay group 82B are arranged symmetrically with respect to the second center line O2. The first phase disconnect relay group 82A opens and closes the power supply path for each of the three phases between the first inverter circuit 81A and the first winding group of the motor 40. The second phase disconnect relay group 82b opens and closes the power supply path for each of the three phases between the second inverter circuit 81B and the second winding group of the motor 40. The phase disconnect relays may be, for example, FETs.

[0041] The second surface of the power substrate 52 includes a first power supply relay 83A and a second power supply relay 83B. The first power supply relay 83A and the second power supply relay 83B are arranged symmetrically with respect to the second center line O2. The first power supply relay 83A opens and closes the power supply path between the vehicle-mounted DC power supply and the first inverter circuit 81A. The second power supply relay 83B opens and closes the power supply path between the vehicle-mounted DC power supply and the second inverter circuit 81B. The DC power supply is, for example, a battery. The power supply relay may also be, for example, an FET.

[0042] The second surface of the power substrate 52 includes a first pre-driver 84A and a second pre-driver 84B. The first pre-driver 84A and the second pre-driver 84B are arranged symmetrically with respect to the second center line O2. The first pre-driver 84A generates a drive signal for the first inverter circuit 81A based on a command from the first microcomputer 61A. The second pre-driver 84B generates a drive signal for the second inverter circuit 81B based on a command from the second microcomputer 61B.

[0043] The second surface of the power substrate 52 includes a third substrate connector 85A and a fourth substrate connector 85B. The third and fourth substrate connectors 85A and 85B are arranged symmetrically with respect to the second center line O2. The third substrate connector 85A is located at a position corresponding to the first substrate connector 62A when the motor unit 31 is assembled. The fourth substrate connector 85B is located at a position corresponding to the second substrate connector 62B when the motor unit 31 is assembled.

[0044] The second surface of the power substrate 52 includes a rotation angle sensor 86 . The rotation angle sensor 86 is located near the center of the second surface. The rotation angle sensor 86 is located on the second center line O2 . The rotation angle sensor 86 is a magnetic sensor, such as an MR sensor (Magneto Resistive Sensor). The rotation angle sensor 86 detects the rotation angle of the motor 40 .

[0045] The first microcomputer 61A generates a command to the first pre-driver 84A based on the rotation angle of the motor 40 detected by the rotation angle sensor 86. The second microcomputer 61B generates a command to the second pre-driver 84B based on the rotation angle of the motor 40 detected by the rotation angle sensor 86.

[0046] <Assembled State of Motor Device 31>

[0047] Next, the assembled state of the motor device 31 will be described.

[0048] like Figure 7 As shown, the motor 40 includes a motor housing 41 and a cover 42. The motor housing 41 has an axially open end. This end is the end of the motor housing 41 on the side where the control device 50 is mounted. The cover 42 fits into the opening of the motor housing 41 to close the opening. The cover 42 functions as an axial end wall of the motor housing 41. The motor housing 41 and the cover 42 are each made of metal. The metal may be, for example, iron or an aluminum alloy.

[0049] The motor 40 has an output shaft 43. The output shaft 43 is supported so as to be rotatable relative to the inner circumferential surface of the motor housing 41. The end of the output shaft 43 passes through the cover 42 in the axial direction in a non-contact state. The end is the end of the output shaft 43 on the side near the control device 50. A magnet 43B is fixed to the end of the output shaft 43 via a retaining frame 43A. A spacer 43C is sandwiched between the end of the output shaft 43 and the magnet 43B. The retaining frame 43A and the spacer 43C are each made of a non-magnetic material such as synthetic resin.

[0050] The control board 51 is housed within the board housing portion 40A. The end of the second ground connection member 63B on the side opposite the control board 51 contacts the inner end wall of the board housing portion 40A. The second ground connection member 63B is maintained slightly compressed in a direction perpendicular to the control board 51. Although not shown, the end of the first ground connection member 63A on the side opposite the control board 51 is also maintained in contact with the inner end wall of the board housing portion 40A. The first ground connection member 63A is maintained slightly compressed in a direction perpendicular to the control board 51.

[0051] The power substrate 52 is supported by the cover 42 so as to cover the control substrate 51. The rotation angle sensor 86 faces the magnet 43B in the axial direction, with the holder 43A interposed therebetween. The fourth substrate connector 85B is connected to the second substrate connector 62B. Although not shown, the third substrate connector 85A is maintained connected to the first substrate connector 62A.

[0052] The second power connector 53B includes a power terminal 53E and a ground terminal 53F. The power terminal 53E and the ground terminal 53F each have a first end and a second end. The first end is located within the peripheral wall of the second power connector 53B. The second end extends perpendicularly through the power substrate 52. The second end is connected to the power substrate 52 by welding. Although not shown, the first power connector 53A also includes a power terminal 53E and a ground terminal 53F.

[0053] The second signal connector 53D has a plurality of signal terminals 53G. Each signal terminal 53G has a first end and a second end. The first end is located within the peripheral wall of the second signal connector 53D. The second end extends perpendicularly through the power substrate 52. The second end is connected to the power substrate 52 by welding. Although not shown, the first signal connector 53C also has a plurality of signal terminals 53G.

[0054] The power substrate 52 is connected to the positive terminal of a DC power supply via a power terminal 53E. The power substrate 52 is connected to the negative terminal of the DC power supply via a ground terminal 53F. DC power from the DC power supply is supplied to the power substrate 52 via the power terminal 53E and the ground terminal 53F. DC power is supplied to the control substrate 51 via the first and third substrate connectors 62A and 85A, and the second and fourth substrate connectors 62B and 85B.

[0055] The power substrate 52 is connected to the vehicle control device via the signal terminals 53G. The power substrate 52 can exchange signals with the vehicle control device via the signal terminals 53G. The control substrate 52 can exchange signals with the vehicle control device via the first and third inter-substrate connectors 62A and 85A, as well as the second and fourth inter-substrate connectors 62B and 85B.

[0056] <Heat Dissipation Structure of Motor Device 31>

[0057] Next, the heat dissipation structure of the motor device 31 will be described.

[0058] like Figure 7 As shown, the control board 51 is fixed to the connector assembly 53. The connector assembly 53 has a plurality of first pillars 53H. Figure 7 Only one first support post 53H is shown. First support post 53H is located at the end of connector assembly 53 opposite the power connectors (53A, 53B). First support post 53H extends toward cover 42. Control board 51 is secured to the front end of first support post 53H with screws 53I. The front end is the end of first support post 53H near cover 42.

[0059] The power substrate 52 is fixed to the connector assembly 53. The connector assembly 53 has a plurality of second pillars 53J. The second pillars 53J are provided at the end of the connector assembly 53 opposite the power connectors (53A, 53B). The second pillars 53J extend toward the cover 42. The protrusion of the second pillars 53J from the connector assembly 53 is shorter than the protrusion of the first pillars 53H from the connector assembly 53. The power substrate 52 is fixed to the front ends of the second pillars 53J with screws 53K. The front ends are the ends of the second pillars 53J on the side near the cover 42.

[0060] The power substrate 52 is also fixed to the cover 42. The cover 42 has a plurality of support portions 42A. Figure 7 Only one support portion 42A is shown. Support portion 42A is provided on the axially outer end surface of cover 42. Power substrate 52 is secured to the front end of support portion 42A by screws 42B. The front end is the end of support portion 42A that is farther from the axially outer end surface of cover 42.

[0061] The cover 42 has a substrate accommodating portion 40A and a heat dissipating portion 40B. The substrate accommodating portion 40A and the heat dissipating portion 40B are provided at the axial end portions of the cover 42. The end portions are the ends of the cover 42 on the axial outer side. The substrate accommodating portion 40A and the heat dissipating portion 40B are adjacent to each other in a direction perpendicular to the axial direction. A height difference is provided between the substrate accommodating portion 40A and the heat dissipating portion 40B. That is, the axial position of the end wall surface of the substrate accommodating portion 40A and the axial position of the end wall surface of the heat dissipating portion 40A are different from each other. The end wall surface of the substrate accommodating portion 40A is axially farther from the end wall of the cover 54 than the end wall surface of the heat dissipating portion 40B. In other words, the end wall surface of the substrate accommodating portion 40A is located axially inward of the motor 40 than the end wall surface of the heat dissipating portion 40B. The end wall surface of the substrate accommodating portion 40A is the first surface of the cover 42. The end wall surface of the heat dissipating portion 40B is the second surface of the cover 42. The heat dissipation portion 40B is a portion of the cover 42 that exchanges heat with the power substrate 52 .

[0062] The end wall surface of the substrate housing portion 40A faces the control substrate 51 in the axial direction. A first gap D1 is formed between the end wall surface of the substrate housing portion 40A and the control substrate 51.

[0063] The power substrate 52 includes a first portion 52A and a second portion 52B. The first portion 52A is the portion of the power substrate 52 that faces the control substrate 51. The second portion 52B is the portion of the power substrate 52 that faces the end wall surface of the heat dissipation section 40B. That is, the second portion 52B does not overlap with the control substrate 51 in the axial direction. A second gap D2 is formed between the second portion 52B and the end wall surface of the heat dissipation section 40B. The second gap D2 is narrower than the first gap D1.

[0064] The thermal resistance between the second portion 52B of the power substrate 52 and the heat dissipation portion 40B is lower than the thermal resistance between the control substrate 51 and the end wall surface of the substrate housing portion 40A. Furthermore, a portion of the power substrate 52 contacts the cover 42. Therefore, the thermal resistance of the heat dissipation path between the power substrate 52 and the cover 42 is lower than the thermal resistance of the heat dissipation path between the control substrate 51 and the cover 42. Thermal resistance is a numerical indicator that quantifies the difficulty of heat transfer. Higher thermal resistance indicates less heat transfer, while lower thermal resistance indicates easier heat transfer.

[0065] The thermal resistance between the control board 51 and the lid 42, and the thermal resistance between the second portion 52B of the power board 52 and the lid 42, includes the thermal resistance due to heat radiation. Radiated heat decays in proportion to the square of the distance between the heat source and the object. If the distance is doubled, the radiated heat decays to 1 / 4, and if the distance is tripled, the heat decays to 1 / 9. The " / " represents division. Therefore, heat generated from the second portion 52B of the power board 52 is more easily transferred to the lid 42 than heat generated from the control board 51.

[0066] The power substrate 52 includes a heat generating element. A heat generating element is an electronic component that generates heat when electricity is applied. The heat generating element includes a high heat generating element. Examples of the high heat generating element include the first power supply circuit 75A, the second power supply circuit 75B, the first pre-driver 84A, and the second pre-driver 84B. Examples of the high heat generating element include the switching element 81A1 of the first inverter circuit 81A and the switching element 81B1 of the second inverter circuit 81B. The switching element 81B1 is one of the electronic components that generates a particularly high amount of heat among the high heat generating elements. The heat generated by the first power supply circuit 75A, the second power supply circuit 75B, the first pre-driver 84A, and the second pre-driver 84B is less than the heat generated by the first inverter circuit 81A and the second inverter circuit 81B.

[0067] The first power supply circuit 75A, the second power supply circuit 75B, the first pre-driver 84A, and the second pre-driver 84B are provided on, for example, the first portion 52A of the power substrate 52. Figure 7 , only the second power supply circuit 75B and the second pre-driver 84B are shown. The switching elements 81A1 and 81B1 are provided, for example, on the second portion 52B of the power substrate 52. The surfaces of the switching elements 81A1 and 81B1 on the opposite side to the second surface of the power substrate 52 are in contact with the heat dissipation portion 40B of the cover 42 via the heat dissipation members 81A2 and 81B2. Figure 7 , only the switching element 81B1 is shown.

[0068] Heat sinks 81A2 and 81B2 are, for example, heat dissipation grease. Heat dissipation grease has high thermal conductivity. Applying heat dissipation grease between switching elements 81A1 and 81B1 and heat dissipation section 40B fills gaps created by minute irregularities between switching elements 81A1 and 81B1 and heat dissipation section 40B. This promotes heat conduction between switching elements 81A1 and 81B1 and heat dissipation section 40B.

[0069] The control substrate 51 includes heating elements. These heating elements include low-heat-generating elements. Examples of these low-heat-generating elements include the first microcomputer 61A and the second microcomputer 61B. The low-heat-generating elements generate less heat than the high-heat-generating elements. Examples of these high-heat-generating elements include the first power supply circuit 75A, the second power supply circuit 75B, the first pre-driver 84A, the second pre-driver 84B, and the switching elements 81A1 and 81B1.

[0070] like Figure 7 As indicated by the dashed arrows, heat generated by the high-heat-generating components of power substrate 52 is dissipated via heat dissipation path A1. Heat dissipation path A1 is a heat conduction path between the high-heat-generating components of power substrate 52 and cover 42. Heat dissipation path A1 includes power substrate 52, the contact area between power substrate 52 and cover 42, and the non-contact area between power substrate 52 and cover 42.

[0071] A portion of the heat is transferred to the cover 42 by thermal conduction through the power substrate 52 and the contact area between the power substrate 52 and the cover 42. The heat generated by the switching elements 81A1 and 81B1 is efficiently transferred to the cover 42 via the heat sinks 81A2 and 81B2. A portion of the heat is directly transferred to the cover 42 by radiation. The heat transferred to the cover 42 is dissipated to the outside through the motor housing 41. A portion of the heat is also transferred to the atmosphere by convection.

[0072] The control substrate 51 does not directly contact the cover 42. Therefore, the heat dissipation of the control substrate 51 is lower than that of the power substrate 52. However, the control substrate 51 does not include high-heat-generating components. High-heat-generating components are provided on the power substrate 52, which is separate from the control substrate 51. Therefore, the first microcomputer 61A and the second microcomputer 61B are less susceptible to heat from the surrounding environment. Therefore, the temperature of the first microcomputer 61A and the second microcomputer 61B can be suppressed to below a predetermined heat-resistant temperature. The heat generated by the first microcomputer 61A and the second microcomputer 61B is transferred to the atmosphere or the cover 42, for example, through convection or radiation.

[0073] <Effects of implementation>

[0074] This embodiment has the following effects.

[0075] (1) The motor 40 includes a motor housing 41 and a cover 42 mounted on an axial end of the motor housing 41. The control substrate 51 includes a low-heat-generating element. The control substrate 51 is arranged to face a portion of the cover 42 in the axial direction of the motor 40. The power substrate 52 includes a high-heat-generating element that generates more heat than the low-heat-generating element. In the axial direction of the motor 40, the power substrate 52 is arranged on the side opposite to the cover 42 relative to the control substrate 51. In other words, in the axial direction of the motor 40, the control substrate 51 is arranged between the cover 42 and the power substrate 52. The power substrate 52 includes a first portion 52A facing the control substrate 51 and a second portion 52B facing the cover 42. The thermal resistance between the second portion 52B of the power substrate 52 and the cover 42 is smaller than the thermal resistance between the control substrate 51 and the cover 42.

[0076] According to this structure, the low-heat-generating element and the high-heat-generating element are arranged on different substrates. Therefore, the heat of the high-heat-generating element is not easily transferred to the control substrate 51, and thus is not easily transferred to the low-heat-generating element. The temperature rise of the low-heat-generating element is suppressed, and thus, the structure for dissipating the heat generated by the low-heat-generating element can be omitted. For example, it is not necessary to make the end wall surface of the substrate accommodating portion 40A contact with the control substrate 51, or to sandwich a heat sink between the end wall surface of the substrate accommodating portion 40A and the control substrate 51.

[0077] The heat generated by the high-heat-generating element is efficiently transferred to the cover 42 via the power substrate 52. This is because the thermal resistance between the second portion 52B of the power substrate 52 and the cover 42 is smaller. If the thermal resistance between the second portion 52B of the power substrate 52 and the cover 42 is smaller than, for example, the thermal resistance between the control substrate 51, which does not require a structure for heat dissipation, and the cover 42, sufficient heat dissipation can be ensured relative to the heat generated by the high-heat-generating element. Therefore, there is no need to provide a heat sink at the end of the motor 40 to ensure heat dissipation. The size of the motor device 31, especially the axial size, can be made smaller compared to when no heat sink is provided. The motor device 31 can also be made lighter compared to when no heat sink is provided.

[0078] (2) The axial distance D2 between the second portion 52B of the power substrate 52 and the cover 42 is shorter than the axial distance D1 between the control substrate 51 and the cover 42. According to this configuration, by making the axial distance D2 between the second portion 52B of the power substrate 52 and the cover 42 shorter than the axial distance D1 between the control substrate 51 and the cover 42, the thermal resistance between the second portion 52B of the power substrate 52 and the cover 42 can be made smaller than the thermal resistance between the control substrate 51 and the cover 42.

[0079] (3) The cover 42 includes a substrate housing portion 40A and a heat dissipation portion 40B. The end wall surface of the substrate housing portion 40A is located axially inward of the motor 40 relative to the end wall surface of the heat dissipation portion 40B. The end wall surface of the substrate housing portion 40A is the surface of the cover 42 facing the control substrate 51. The end wall surface of the heat dissipation portion 40B is the surface of the cover 42 facing the second portion 52B of the power substrate 52. According to this structure, the volume of the cover 42 can be reduced in accordance with the end wall surface of the substrate housing portion 40A being located axially inward of the motor 40 relative to the end wall surface of the heat dissipation portion 40B. In other words, the axial thickness of the portion of the cover 42 facing the control substrate 51 can be made thinner. The motor device 31 can be made lighter in accordance with the reduction in the volume of the cover 42.

[0080] (4) The motor device 31 includes a connector assembly 53 made of synthetic resin. In the axial direction of the motor 40, the connector assembly 53 is arranged at a position farther from the cover 42 than the power substrate 52. In other words, in the axial direction of the motor 40, the connector assembly 53 is arranged on the opposite side of the cover 42 relative to the power substrate 52. The connector assembly 53 holds a plurality of terminals for supplying power or signals to the control substrate 51 and the power substrate 52. The terminals include a power terminal 53E, a ground terminal 53F, and a signal terminal 53G. The control substrate 51 is fixed to the connector assembly 53. The power substrate 52 is fixed to both the connector assembly 53 and the cover 42. According to this structure, the heat generated by the high-heat-generating element is transferred to the cover 42 via the power substrate 52. Since the control substrate 51 is not fixed to the cover 42, the heat transferred to the cover 42 is not easily transferred from the cover 42 to the control substrate 51. Therefore, the temperature rise of the control substrate 51 is suppressed.

[0081] (5) The control substrate 51 and the power substrate 52 exchange power and signals via the inter-substrate connectors (62A, 85A, 62B, 85B). The power substrate 52 includes a power supply circuit (75A, 75B). The power supply circuit converts the voltage of the vehicle-mounted DC power supply into a voltage suitable for the operation of the electrical circuits, including the microcomputer (61A, 61B) provided on the control substrate 51. Only the voltage converted by the power supply circuit is supplied to the control substrate 51 via the inter-substrate connector. The voltage converted by the power supply circuit is lower than the voltage of the vehicle-mounted DC power supply. Therefore, for example, compared to the case where the voltage from the vehicle-mounted DC power supply is supplied to the control substrate 51, heat generation of the control substrate 51 can be suppressed.

[0082] (6) The high-heat-generating element includes switching elements 81A1 and 81B1, pre-drivers (84A and 84B), and power supply circuits (75A and 75B). Switching elements 81A1 and 81B1 are located on the second portion 52B of the power substrate 52. Pre-drivers (84A and 84B) and power supply circuits (75A and 75B) are located on the first portion 52A of the power substrate 52.

[0083] The first portion 52A of the power substrate 52 is the portion of the power substrate 52 that faces the control substrate 51. Therefore, there is a risk of heat being transferred from the first portion 52A of the power substrate 52 to the control substrate 51, for example, through radiation. In this regard, the above-described configuration reduces the amount of heat transferred from the first portion 52A of the power substrate 52 to the control substrate 51, compared to, for example, a case where the inverter circuit (81A, 81B) is provided in the first portion 52A of the power substrate 52. This is because the pre-driver (84A, 84B) and power supply circuit (75A, 75B) generate less heat than the inverter circuit (81A, 81B).

[0084] (7) The switching elements 81A1 and 81B are provided on the surface of the power substrate 52 facing the cover 42. The switching elements 81A1 and 81B are in contact with the cover 42 via the heat sinks 81A2 and 81B2. With this structure, the heat generated by the switching elements 81A1 and 81B is efficiently transferred to the cover 42 via the heat sinks 81A2 and 81B2.

[0085] (8) The control system and power supply system of the motor 40 are each two systems. The number of electronic components on the control substrate 51 and the power substrate 52 is twice that of a case where the control system and power supply system of the motor 40 are each one system. Therefore, the mounting density of the electronic components on the substrate becomes higher. Therefore, for example, when a high-heat-generating element and a low-heat-generating element are installed on the same substrate, the multiple electronic components transfer heat to each other, which easily causes the temperature of the electronic components to rise.

[0086] For example, consider installing the microcomputer (61A, 61B), a low-heat-generating component, and the pre-driver (81A, 81B), a high-heat-generating component, and the power supply circuit (75A, 75B), on the same substrate. In this case, there is a concern not only about the high-heat-generating component but also about the microcomputer (61A, 61B), a low-heat-generating component. Therefore, it is necessary to provide a structure in the motor unit 31 to suppress the temperature rise of the microcomputer (61A, 61B).

[0087] In this embodiment, the microcomputer (61A, 61B), pre-driver (81A, 81B), and power supply circuit (75A, 75B) are distributed on separate substrates. This reduces heat transfer between the microcomputer (61A, 61B) and pre-driver (81A, 81B), and between the microcomputer (61A, 61B) and power supply circuit (75A, 75B). This reduces the temperature rise of the microcomputer (61A, 61B). This eliminates the need for a separate structure in the motor device 31 to reduce the temperature rise of the microcomputer (61A, 61B). This embodiment is suitable for a motor device 31 having multiple control systems and multiple power supply systems.

[0088] <Other Implementation Methods>

[0089] This embodiment can also be implemented with modifications as follows.

[0090] Heat sinks 81A2 and 81B2 can also be omitted. In this case, a gap is formed between switching elements 81A1 and 81B1 and heat sink 40B. The gap is relatively small. Therefore, the heat generated by switching elements 81A1 and 81B1 is efficiently transferred to heat sink 40B, for example, by radiation.

[0091] Instead of fixing the power substrate 52 to the connector assembly 53 and the cover 42, the power substrate 52 may be fixed to the connector assembly 53 and the motor housing 41, for example. In this case, for example, a support portion for supporting the power substrate 52 is provided on the motor housing 41. This also ensures heat dissipation from the power substrate 52.

[0092] The motor 40 may also be a motor having a single winding system. Furthermore, the control system and power supply system of the motor 40 may each be a separate system. In this case, the connector assembly 53 may be configured such that the first power connector 53A and the first signal connector 53C are omitted, or the second power connector 53B and the second signal connector 53D are omitted.

Claims

1. A motor device, characterized in that: have: A motor having a metal motor housing and a metal end wall mounted on an axial end of the motor housing; a first substrate having a low-heat-generating element and arranged to face a portion of the end wall in the axial direction of the motor, and configured to control power supply to the motor; as well as a second substrate having a high-heat-generating element that generates more heat than the low-heat-generating element and arranged on the side of the first substrate opposite to the end wall in the axial direction of the motor, and configured to supply power to the motor under control based on the first substrate; The second substrate has a first portion facing the first substrate and a second portion facing the end wall. The thermal resistance between the second portion and the end wall is smaller than the thermal resistance between the first substrate and the end wall.

2. The motor device according to claim 1, wherein: An axial distance between the second portion and the end wall is shorter than an axial distance between the first substrate and the end wall.

3. The motor device according to claim 1 or 2, characterized in that: The end wall has a first surface facing the first substrate and a second surface facing the second portion of the second substrate. The first surface is located axially inward of the motor relative to the second surface.

4. The motor device according to claim 1 or 2, characterized in that: A connector assembly is further provided, the connector assembly being made of synthetic resin and arranged at a position farther from the end wall than the second substrate in the axial direction of the motor, and holding a plurality of terminals configured to supply power or signals to the first substrate and the second substrate. The first substrate is fixed to the connector assembly. The second substrate is fixed to the connector assembly and the end wall or the motor housing.

5. The motor device according to claim 1 or 2, characterized in that: further comprising an inter-substrate connector that connects the first substrate and the second substrate and is configured to exchange power and signals between the first substrate and the second substrate; The high heat generating element includes a power supply circuit configured to convert a voltage supplied from an external power source into a voltage suitable for the operation of the electric circuit including the low heat generating element provided on the first substrate. The inter-board connector is configured to supply only the voltage converted by the power supply circuit to the first board.

6. The motor device according to claim 1 or 2, characterized in that: The high-heat-generating element comprises: a switching element constituting an inverter circuit for supplying electric power to the motor; a pre-driver configured to drive the inverter circuit based on a command from the first substrate; and a power supply circuit configured to convert a voltage supplied from an external power supply into a voltage suitable for the operation of the electric circuit including the low-heat-generating element provided on the first substrate; The switching element is arranged on the second portion of the second substrate. The pre-driver and the power supply circuit are arranged on the first portion of the second substrate.

7. The motor device according to claim 6, characterized in that The switching element is provided on a surface of the second substrate facing the end wall, and is in contact with the end wall via a heat sink.

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