Electric drive unit and electric power steering system

Abstract

To provide an electric drive unit and an electric power steering system, which improve assembly workability of insertion of a head of an electrolytic capacitor for smoothing into a recess, while suppressing the heat generation of a driving element of an inverter circuit and the electrolytic capacitor for smoothing.SOLUTION: An electric drive unit comprises a motor having a flange part, and an electronic control device that controls motor rotation. The electronic control device includes a circuit board and a lid body. The motor includes a bearing holder. The bearing holder includes a bearing holder base, and a first recess which is positioned on the radial outside of a bearing in an axial view, which is depressed to a load side from an anti-load side surface of the bearing holder base and which assumes an arc shape in a longitudinal direction. A plurality of electrolytic capacitors of the circuit board are housed in the first recess.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to an electric drive device and an electric power steering device that include an electronic control device that controls the rotation of a motor. [Background technology]

[0002] An electric power steering device that generates an auxiliary steering torque by means of a motor is equipped with an electronic control device that controls the motor (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 088162 [Patent Document 2] Japanese Patent Publication No. 2023-086611 Summary of the Invention [Problem to be solved by the invention]

[0004] The electric drive device of Patent Document 1 has a heat sink to improve the heat dissipation efficiency of the multiple electrolytic capacitors, and has multiple recesses for accommodating the respective electrolytic capacitors.

[0005] In the electric drive device of Patent Document 2, the load-side surface of the top plate of the lid is in contact with the electrolytic capacitor via a heat dissipation material.

[0006] The heat generated by the smoothing electrolytic capacitor is smaller than that generated by the drive element of the inverter circuit that outputs the current that excites the coil, and the axial height of the smoothing electrolytic capacitor is greater than the axial height of the drive element of the inverter circuit.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an electric drive device and an electric power steering device that improve the assembly workability of inserting the head of the smoothing electrolytic capacitor into the recess while suppressing heat generation in the drive element of the inverter circuit and the smoothing electrolytic capacitor. [Means for solving the problem]

[0008] In order to achieve the above object, one embodiment of the electric drive device is an electric drive device including a motor and an electronic control device that controls rotation of the motor, wherein the motor includes a shaft extending axially from a load side to an anti-load side, a motor rotor that interlocks with the shaft, a motor stator that rotates the motor rotor, a housing that houses the motor rotor and the motor stator, a flange portion provided on the anti-load side of the housing, a magnet provided on the anti-load side of the shaft, a bearing that rotatably supports the shaft, and a bearing holder that supports the bearing, and the electronic control device includes a circuit board and a metal cover that covers the circuit board, and the circuit board includes a double-sided mountable board main body and a plurality of smoothing electrolytic capacitors arranged on a first surface of the board main body on the load side. the cover body includes a top plate portion and a first heat receiving surface of the cover body that receives heat from the drive element via a heat dissipation material; the bearing holder includes a base portion of the bearing holder and a first recess portion that is recessed from the surface of the base portion of the bearing holder on the anti-load side toward the load side and has an arc-shaped longitudinal direction, and is located radially outward of the bearing in the axial direction; the plurality of electrolytic capacitors are arranged along a curve centered on a reference point on the axial extension of the shaft, as viewed in the axial direction, and the plurality of electrolytic capacitors are housed in the first recess portion.

[0009] This allows heat generated by the inverter circuit to be dissipated to the cover, and heat generated by the smoothing electrolytic capacitor to be dissipated to the bearing holder.The electrolytic capacitors are then lined up in an arc and inserted into the arc-shaped first recess.When the circuit board is installed, even if the circuit board swings in the rotational direction, the electrolytic capacitors are unlikely to hit the wall of the first recess, so this configuration improves the ease of assembly work of inserting the heads of the smoothing electrolytic capacitors into the recess.Since the electrolytic capacitors are housed in the first recess, the axial size of the electric drive device is reduced.

[0010] In a preferred embodiment, adjacent electrolytic capacitors are spaced apart, and the angle between the farthest electrolytic capacitor and the reference point is 90 degrees or more and less than 180 degrees. If this angle exceeds 180 degrees, the electrolytic capacitors are likely to hit the walls of the first recess when the circuit board is inserted at an angle. In contrast, with the above configuration, the electrolytic capacitors are less likely to hit the walls of the first recess.

[0011] In a preferred embodiment, a second recess having an arc-shaped longitudinal direction is provided on an extension of the first recess as viewed in the axial direction, recessed from the anti-load side surface of the base of the bearing holder toward the load side, thereby reducing the weight of the electric drive device.

[0012] In a preferred embodiment, a third recess is provided between the first recess and the second recess in the axial direction, recessed from the anti-load side surface of the base of the bearing holder toward the load side and having an arc-shaped longitudinal direction, and thick portions are provided between the first recess and the second recess, between the second recess and the third recess, and between the third recess and the first recess, respectively. This allows the weight of the electric drive device to be reduced while ensuring the rigidity of the bearing holder to support the bearing.

[0013] In a preferred embodiment, the motor stator comprises a stator core that rotates the motor rotor, and a plurality of coil groups that are divided into at least two systems of coil groups, a first coil group and a second coil group, for each three phase, and that excite the stator core with three-phase AC; the circuit board includes, on the second surface, a first inverter circuit mounting area that mounts a first inverter circuit that supplies current to the first coil group, and a second inverter circuit mounting area that mounts a second inverter circuit that supplies current to the second coil group; the first inverter circuit mounting area is arranged on the edge of a first side of the circuit board; the second inverter circuit mounting area is arranged on the edge of a second side that is adjacent to the first side and in a direction different from the first side; and the plurality of electrolytic capacitors are arranged radially inward of the first inverter circuit mounting area and the second inverter circuit mounting area. As a result, the electrolytic capacitors are adjacent to the first inverter circuit and the second inverter circuit without overlapping with each other in the axial direction, so that the heat generated by the first inverter circuit and the second inverter circuit and the heat generated by the electrolytic capacitors are less likely to overlap, thereby increasing the packaging density of the circuit board and further miniaturizing the electric drive device.

[0014] In a preferred embodiment, the electric power steering system includes an electric drive unit that generates an auxiliary steering torque, thereby suppressing heat generation and improving the reliability of the electric power steering system. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to provide an electric drive device and an electric power steering device that improve the assembly workability of inserting the head of the smoothing electrolytic capacitor into the recess while suppressing heat generation in the drive element of the inverter circuit and the smoothing electrolytic capacitor. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view that schematically shows a vehicle equipped with an electric power steering device according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram of the electric power steering device according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view schematically showing a cross section of the motor according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram showing wiring of the motor according to the first embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the relationship between the motor and the ECU according to the first embodiment. [Figure 6] FIG. 6 is a side view of the electric drive device according to the first embodiment. [Figure 7] FIG. 7 is a plan view of the electric drive device according to the first embodiment. [Figure 8] FIG. 8 is a perspective view of the electric drive device according to the first embodiment with the cover removed. [Figure 9] FIG. 9 is a perspective view of the back surface of the lid according to the first embodiment. [Figure 10] FIG. 10 is a plan view of the electric drive device according to the first embodiment with the circuit board removed. [Figure 11] FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. [Figure 12] FIG. 12 is an enlarged partial cross-sectional view of FIG. [Figure 13] 13 is a cross-sectional view taken along the line XII-XII in FIG. [Figure 14] FIG. 14 is a plan view illustrating a state in which electronic components are mounted on the second surface of the circuit board according to the first embodiment. [Figure 15] FIG. 15 is a plan view illustrating a state in which electronic components are mounted on the first surface of the circuit board according to the first embodiment. [Figure 16] FIG. 16 is a schematic diagram of an electric power steering device according to the second embodiment. [Figure 17] FIG. 17 is a schematic diagram of an electric power steering device according to the third embodiment. [Figure 18] FIG. 18 is a schematic diagram of an electric power steering device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Modes (embodiments) for carrying out the present disclosure will be described in detail with reference to the drawings. The present disclosure is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the components described below can be combined as appropriate.

[0018] (Embodiment 1) Fig. 1 is a perspective view that schematically shows a vehicle equipped with an electric power steering device according to embodiment 1. Fig. 2 is a schematic diagram of the electric power steering device according to embodiment 1. As shown in Fig. 1, a vehicle 101 is equipped with an electric power steering device 100. An overview of the electric power steering device 100 will be described with reference to Fig. 2.

[0019] The electric power steering device 100 includes, in the order in which a force applied by a driver (operator) is transmitted, a steering wheel 191, a steering shaft 192, a universal joint 196, an intermediate shaft 197, a universal joint 198, a first rack-and-pinion mechanism 199, and a tie rod 172. The electric power steering device 100 also includes a torque sensor 194 that detects the steering torque of the steering shaft 192, a motor 30, an electronic control unit (hereinafter referred to as an ECU (Electronic Control Unit)) 10 that controls the motor 30, and a reduction gear 175. A vehicle speed sensor 182, a power supply device 183 (e.g., an on-board battery), and an ignition switch 184 are provided on the vehicle body. The vehicle speed sensor 182 detects the traveling speed of the vehicle 101. The vehicle speed sensor 182 outputs the detected vehicle speed signal SV to the ECU 10 via CAN (Controller Area Network) communication. The ECU 10 is supplied with power from a power supply device 183 when an ignition switch 184 is in an on state.

[0020] As shown in Fig. 2, the steering shaft 192 includes an input shaft 192A and an output shaft 192B. One end of the input shaft 192A is connected to the steering wheel 191, and the other end is connected to the torsion bar. One end of the output shaft 192B is connected to the torsion bar, and the other end is connected to a universal joint 196. The torque sensor 194 detects the torsion of the torsion bar to detect the steering torque applied to the steering shaft 192. The torque sensor 194 outputs a steering torque signal T corresponding to the detected steering torque to the ECU 10. The steering shaft 192 rotates due to the steering force applied to the steering wheel 191.

[0021] Intermediate shaft 197 transmits torque from output shaft 192B. First rack and pinion mechanism 199 has a first pinion shaft 199A, a first pinion gear 199B, a rack shaft 199C, and a first rack 199D. One end of first pinion shaft 199A is connected to intermediate shaft 197 via universal joint 198, and the other end is connected to first pinion gear 199B. First rack 199D formed on rack shaft 199C meshes with first pinion gear 199B.

[0022] As described above, the rotational motion of the steering shaft 192 is transmitted to the first rack and pinion mechanism 199 via the intermediate shaft 197. This rotational motion is converted into linear motion of the rack shaft 199C by the first rack and pinion mechanism 199. The tie rods 172 are connected to both ends of the rack shaft 199C.

[0023] The motor 30 generates an auxiliary steering torque to assist the driver in steering, and may be a brushless motor or a brush motor having brushes and a commutator.

[0024] The ECU 10 includes a rotation angle sensor 23a. The rotation angle sensor 23a detects the rotation phase of the motor 30. The ECU 10 acquires a rotation phase signal of the motor 30 from the rotation angle sensor 23a, acquires a steering torque signal T from the torque sensor 194, and acquires a vehicle speed signal SV of the vehicle 101 from the vehicle speed sensor 182. The ECU 10 calculates an assist steering command value of the assist command based on the rotation phase signal, the steering torque signal T, and the vehicle speed signal SV. The ECU 10 supplies a current to the motor 30 based on the calculated assist steering command value.

[0025] The electric drive device 1 includes a motor 30 and an ECU 10 fixed to the anti-load side of the shaft of the motor 30. The electric drive device 1 may also include an adapter that connects the ECU 10 and the motor 30.

[0026] The reduction gear 175 includes a worm shaft that rotates integrally with the shaft 31 of the motor 30, and a worm wheel that meshes with the worm shaft. Therefore, the rotational motion of the shaft of the motor 30 is transmitted to the worm wheel via the worm shaft. In the first embodiment, the end of the motor shaft on the reduction gear 175 side is referred to as the load side end, and the end of the motor shaft opposite the reduction gear 175 is referred to as the anti-load side end.

[0027] The steering force of the driver input to the steering wheel 191 is transmitted to the first rack-and-pinion mechanism 199 via the steering shaft 192 and the intermediate shaft 197. The first rack-and-pinion mechanism 199 transmits the transmitted steering force to the rack shaft 199C as a force applied in the axial direction of the rack shaft 199C. At this time, the ECU 10 acquires the steering torque signal T input to the steering shaft 192 from the torque sensor 194. The ECU 10 acquires the vehicle speed signal SV from the vehicle speed sensor 182. The ECU 10 acquires the rotation phase signal of the motor 30 from the rotation angle sensor 23a. The ECU 10 then outputs a control signal to control the operation of the motor 30. The auxiliary steering torque generated by the motor 30 is transmitted to the output shaft 192B via the reduction gear 175. In this manner, the electric power steering device 100 assists the steering of the steering wheel 191 by the driver.

[0028] As shown in FIG. 2, the electric power steering device 100 is of a column assist type in which an assist force is applied to the output shaft 192B of the steering shaft 192.

[0029] FIG. 3 is a cross-sectional view schematically illustrating a cross section of the motor according to the first embodiment. FIG. 4 is a schematic diagram illustrating wiring of the motor according to the first embodiment. In the first embodiment, the circumferential direction is a direction along a concentric circle centered on the shaft 31. The radial direction is a direction away from the shaft 31 in a plane perpendicular to the axial direction AX. As shown in FIG. 3, the motor 30 includes a housing 930, a motor stator having a stator core 931, and a motor rotor 932. The motor stator includes the cylindrical stator core 931, a plurality of first coils 37, and a plurality of second coils 38. The stator core 931 includes an annular back yoke 931a and a plurality of teeth 931b protruding from the inner circumferential surface of the back yoke 931a. Twelve teeth 931b are arranged in the circumferential direction. The motor rotor 932 includes a rotor yoke 932a and a magnet 932b. The magnets 932b are provided on the outer peripheral surface of the rotor yoke 932a. The number of magnets 932b is, for example, 8. The rotation of the motor rotor 932 is linked to the rotation of the shaft 31.

[0030] As shown in FIG. 3, the first coil 37 is concentratedly wound around each of the multiple teeth 931b. The first coil 37 is concentratedly wound around the outer periphery of the tooth 931b with an insulator interposed therebetween. All of the first coils 37 are included in a first coil system. The first coil system according to the first embodiment is supplied with current and excited by a first inverter circuit 251A (see FIG. 5) included in the first power circuit 25A. The first coil system includes, for example, six first coils 37. The six first coils 37 are arranged so that two first coils 37 are adjacent to each other in the circumferential direction. Three first coil groups Gr1, each consisting of adjacent first coils 37, are arranged at equal intervals in the circumferential direction. That is, the first coil system includes three first coil groups Gr1 arranged at equal intervals in the circumferential direction. The number of first coil groups Gr1 does not necessarily have to be three; it is sufficient that 3n first coil groups Gr1 are arranged at equal intervals in the circumferential direction, where n is a natural number. Furthermore, it is preferable that n is an odd number. As described above, in the first embodiment, there are a plurality of coil groups, and each of the three phases is divided into at least two systems, a first coil group Gr1 and a second coil group Gr2, and the stator core is excited by three-phase AC.

[0031] As shown in FIG. 3, the second coil 38 is concentratedly wound around each of the multiple teeth 931b. The second coil 38 is concentratedly wound around the outer periphery of the teeth 931b with an insulator interposed therebetween. The teeth 931b around which the second coil 38 is concentratedly wound are different from the teeth 931b around which the first coil 37 is concentratedly wound. All of the second coils 38 are included in a second coil system. The second coil system is supplied with current and excited by a second inverter circuit 251B (see FIG. 5) included in the second power circuit 25B. The second coil system includes, for example, six second coils 38. The six second coils 38 are arranged so that two second coils 38 are adjacent to each other in the circumferential direction. Three second coil groups Gr2, each consisting of adjacent second coils 38, are arranged at equal intervals in the circumferential direction. That is, the second coil system includes three second coil groups Gr2 arranged at equal intervals in the circumferential direction. The number of second coil groups Gr2 does not necessarily have to be three, but may be 3n, where n is a natural number, and it is preferable that n is an odd number.

[0032] 4, the six first coils 37 include two first U-phase coils 37Ua and 37Ub excited by a first U-phase current I1u, two first V-phase coils 37Va and 37Vb excited by a first V-phase current I1v, and two first W-phase coils 37Wa and 37Wb excited by a first W-phase current I1w. 1U-phase coil 37Ub is connected in series to 1U-phase coil 37Ua. 1V-phase coil 37Vb is connected in series to 1V-phase coil 37Va. 1W-phase coil 37Wb is connected in series to 1W-phase coil 37Wa. All of the first coils 37 are wound in the same direction around teeth 931b. Furthermore, first U-phase coil 37Ub, first V-phase coil 37Vb, and first W-phase coil 37Wb are joined together in a star connection (Y connection).

[0033] 4, the six second coils 38 include two second U-phase coils 38Ua and 38Ub excited by a second U-phase current I2u, two second V-phase coils 38Va and 38Vb excited by a second V-phase current I2v, and two second W-phase coils 38Wa and 38Wb excited by a second W-phase current I2w. 2U-phase coil 38Ub is connected in series to 2U-phase coil 38Ua. 2V-phase coil 38Vb is connected in series to 2V-phase coil 38Va. 2W-phase coil 38Wb is connected in series to 2W-phase coil 38Wa. The winding directions of all second coils 38 about teeth 931b are the same as the winding direction of first coil 37. Furthermore, the second U-phase coil 38Ub, the second V-phase coil 38Vb, and the second W-phase coil 38Wb are joined together in a star connection (Y connection).

[0034] 3, the three first coil groups Gr1 are comprised of a first UV coil group Gr1UV, a first VW coil group Gr1VW, and a first UW coil group Gr1UW. The first UV coil group Gr1UV includes a first U-phase coil 37Ub and a first V-phase coil 37Va that are adjacent to each other in the circumferential direction. The first VW coil group Gr1VW includes a first V-phase coil 37Vb and a first W-phase coil 37Wa that are adjacent to each other in the circumferential direction. The first UW coil group Gr1UW includes a first U-phase coil 37Ua and a first W-phase coil 37Wb that are adjacent to each other in the circumferential direction.

[0035] 3, the three second coil groups Gr2 are composed of a second UV coil group Gr2UV, a second VW coil group Gr2VW, and a second UW coil group Gr2UW. The second UV coil group Gr2UV includes a second U-phase coil 38Ub and a second V-phase coil 38Va that are adjacent to each other in the circumferential direction. The second VW coil group Gr2VW includes a second V-phase coil 38Vb and a second W-phase coil 38Wa that are adjacent to each other in the circumferential direction. The second UW coil group Gr2UW includes a second U-phase coil 38Ua and a second W-phase coil 38Wb that are adjacent to each other in the circumferential direction.

[0036] First coil 37, which is excited by first U-phase current I1u, faces second coil 38, which is excited by second U-phase current I2u, in the radial direction of stator core 931. In the following description, the radial direction of stator core 931 will be simply referred to as the radial direction. For example, as shown in FIG. 3, first U-phase coil 37Ua faces second U-phase coil 38Ua, and first U-phase coil 37Ub faces second U-phase coil 38Ub in the radial direction.

[0037] First coil 37, excited by first V-phase current I1v, faces, in the radial direction, second coil 38, excited by second V-phase current I2v. For example, as shown in Fig. 3, first V-phase coil 37Va faces, in the radial direction, second V-phase coil 38Va, and first V-phase coil 37Vb faces, in the radial direction, second V-phase coil 38Vb.

[0038] First coil 37, which is excited by first W-phase current I1w, faces, in the radial direction, second coil 38, which is excited by second W-phase current I2w. For example, as shown in Fig. 3, first W-phase coil 37Wa faces, in the radial direction, second W-phase coil 38Wa, and first W-phase coil 37Wb faces, in the radial direction, second W-phase coil 38Wb.

[0039] Fig. 5 is a schematic diagram showing the relationship between the motor and the ECU according to embodiment 1. As shown in Fig. 5, the ECU 10 includes a detection circuit 23, a control circuit 24, a first power circuit 25A, a second power circuit 25B, a power supply management circuit 27, a breaker drive circuit 243, and a power supply relay drive circuit 246. Note that in Fig. 5, circuits that do not require explanation are omitted as appropriate.

[0040] The control circuit 24 has a control arithmetic circuit 241, a first motor drive circuit 26A, and a second motor drive circuit 26B. Input / output signals such as a steering torque signal T and a vehicle speed signal SV are transmitted to the control arithmetic circuit 241 via a connector CNT. Since the circuit board 20 is a multilayer resin board provided with multiple conductive layers, the connection wiring electrically connecting the connector CNT to the control arithmetic circuit 241 of the control circuit 24 is routed on the internal conductive layers of the circuit board 20.

[0041] Power is supplied to the wiring PW from the power supply device 183 via a connector CNT. The noise filter circuit 90 has a choke coil 91 and a capacitor 92, and removes high-frequency components superimposed on the power supplied from the wiring PW. The connection wiring PWS routed to the circuit board 20 is connected to the wiring PW from the power supply device 183. One end of the connection wiring PWS is connected to the noise filter circuit 90 (choke coil 91, capacitor 92), and the other end of the connection wiring is connected to the first inverter circuit 251A of the first power circuit 25A or the second inverter circuit 251B of the second power circuit 25B via a power supply circuit 256. When the first inverter circuit 251A and the second inverter circuit 251B are not to be distinguished from each other, they will be simply referred to as the inverter circuit 251.

[0042] The power supply circuit 256 is disposed between the noise filter circuit 90 and the inverter circuit 251. The power supply circuit 256 includes a power cutoff element 257 and a reverse connection protection element 258. The power cutoff element 257 and the reverse connection protection element 258 are field effect transistors (FETs). The forward direction of the parasitic diode of the reverse connection protection element 258 is opposite to the forward direction of the parasitic diode of the power cutoff element 257. Therefore, even if reverse polarity power is mistakenly supplied from the power supply device 183, the reverse connection protection element 258 cuts off the reverse polarity power and protects the inverter circuit 251.

[0043] The power supply management circuit 27 is a switching IC that controls the ON / OFF of the power supply and the distribution of power to the circuits mounted on the circuit board 20. The power supply management circuit 27 controls, for example, the distribution of power used by the control circuit 24. One end of the connection wiring is connected to the noise filter circuit 90 (choke coil 91, capacitor 92), and the other end of the connection wiring is connected to the power supply management circuit 27.

[0044] The detection circuit 23 has two rotation angle sensors 23a and a sensor control unit 23b. The detection circuit 23 can continue to function even if one rotation angle sensor 23a fails. The first power circuit 25A has a first inverter circuit 251A and a current interruption circuit 255. The second power circuit 25B has a second inverter circuit 251B and a current interruption circuit 255.

[0045] The first motor drive circuit 26A has a first gate drive circuit 242a, multiple current detection circuits 244, and a boost circuit 245. The second motor drive circuit 26B has a second gate drive circuit 242b, multiple current detection circuits 244, and a boost circuit 245. The boost circuit 245 supplies boosted power to the first gate drive circuit 242a, the second gate drive circuit 242b, the breaker drive circuit 243, and the power relay drive circuit 246.

[0046] When the power relay drive circuit 246 turns on the power cutoff element 257 and the reverse connection protection element 258 based on the control of the control calculation circuit 241 , power from the power supply device 183 is supplied to each inverter circuit 251 .

[0047] The inverter circuit 251 also has a plurality of drive elements 252. The drive elements 252 are field effect transistors (FETs), also called switching elements. The drive elements 252 connected to the high potential side constitute an upper arm, and the drive elements 252 connected to the low potential side constitute a lower arm. A shunt resistor SR is connected to each of the three drive elements 252 in the lower arm. Note that one shunt resistor SR is connected to each of the three drive elements 252, but only one shunt resistor SR may be connected to each of the three drive elements 252.

[0048] The control and calculation circuit 241 controls the first motor drive circuit 26A or the second motor drive circuit 26B. For example, the control and calculation circuit 241 calculates a motor current command value and controls the first motor drive circuit 26A or the second motor drive circuit 26B using the motor current command value. The sensor control unit 23b calculates the motor electrical angle θm based on the detection value of the rotation angle sensor 23a and outputs it to the control and calculation circuit 241. The first gate drive circuit 242 controls the first power circuit 25A based on the motor current command value. The second gate drive circuit 242b controls the second power circuit 25B based on the motor current command value. In this way, the current flowing to the first coil 37 and the current flowing to the second coil 38 are each independently controlled by the control and calculation circuit 241.

[0049] 5, the ECU 10 includes a rotation angle sensor 23a. The rotation angle sensor 23a is, for example, a magnetic sensor. A detection value of the rotation angle sensor 23a is supplied to a sensor control unit 23b. The sensor control unit 23b outputs an output value corresponding to the motor electrical angle θm to a control calculation circuit 241 based on the detection value of the rotation angle sensor 23a.

[0050] The control calculation circuit 241 receives as input the steering torque signal T detected by the torque sensor 194, the vehicle speed signal SV detected by the vehicle speed sensor 82, and an output value corresponding to the motor electrical angle θm output from the sensor control unit 23b. The control calculation circuit 241 calculates a motor current command value based on the steering torque signal T, the vehicle speed signal SV, and the motor electrical angle θm calculated from the above output value, and outputs the motor current command value to the first gate drive circuit 242a and the second gate drive circuit 242b.

[0051] First gate drive circuit 242a calculates a first pulse-width modulated signal based on the motor current command value and outputs the gate drive signal to first inverter circuit 251A of first power circuit 25A. The gate drive signal is a pulse signal generated based on the gate voltage boosted by boost circuit 245. First inverter circuit 251A switches drive element 252 to generate three-phase current values ​​according to the duty ratio of the first pulse-width modulated signal, thereby generating a three-phase AC current including a first U-phase current I1u, a first V-phase current I1v, and a first W-phase current I1w. The first U-phase current I1u excites first U-phase coil 37Ua and first U-phase coil 37Ub, the first V-phase current I1v excites first V-phase coil 37Va and first V-phase coil 37Vb, and the first W-phase current I1w excites first W-phase coil 37Wa and first W-phase coil 37Wb.

[0052] Second gate drive circuit 242b calculates a second pulse-width modulated signal based on the motor current command value and outputs the gate drive signal to second inverter circuit 251b of second power circuit 25B. The gate drive signal is generated based on the voltage boosted by boost circuit 245. Second inverter circuit 251b switches drive element 252 to generate three-phase current values ​​according to the duty ratio of the second pulse-width modulated signal, thereby generating a three-phase AC current including a second U-phase current I2u, a second V-phase current I2v, and a second W-phase current I2w. The second U-phase current I2u excites second U-phase coil 38Ua and second U-phase coil 38Ub, the second V-phase current I2v excites second V-phase coil 38Va and second V-phase coil 38Vb, and the second W-phase current I2w excites second W-phase coil 38Wa and second W-phase coil 38Wb.

[0053] The inverter circuit 251 is a power conversion circuit that converts DC power into AC power. As described above, the inverter circuit 251 has a plurality of drive elements 252. The drive elements 252 are, for example, field effect transistors. A smoothing electrolytic capacitor 253 is connected in parallel to the inverter circuit 251. In other words, the circuit board 20 includes a plurality of electrolytic capacitors (four electrolytic capacitors in the first embodiment) connected in parallel.

[0054] The current detection circuit 244 is also connected to, for example, a shunt resistor SR. The shunt resistor SR is an example of a current detection element. The current detection element may be a Hall element or the like. The current detection circuit 244 includes a differential amplifier circuit using an operational amplifier and a low-pass filter. The differential amplifier circuit of the current detection circuit 244 amplifies the signal of the detection value detected by the shunt resistor SR, attenuates components higher than the cutoff frequency of the amplified detection value via a low-pass filter, and sends the detection value detected by the shunt resistor SR to the control calculation circuit 241 as a current value.

[0055] The current interruption circuit 255 is disposed between the inverter circuit 251 and the first coil 37 or the second coil 38. If the current value detected by the current detection circuit 244 is determined to be abnormal, the control and calculation circuit 241 drives the current interruption circuit 255 via the interruption drive circuit 243 to interrupt the current flowing from the inverter circuit 251 to the first coil 37. The control and calculation circuit 241 also drives the current interruption circuit 255 via the interruption drive circuit 243 to interrupt the current flowing from the inverter circuit 251 to the second coil 38. If the current value detected by the current detection circuit 244 is determined to be abnormal, the control and calculation circuit 241 turns off the power interruption element 257 and the reverse connection protection element 258 via the power relay drive circuit 246 to protect the inverter circuit 251.

[0056] FIG. 6 is a side view of the electric drive device according to the first embodiment. FIG. 7 is a plan view of the electric drive device according to the first embodiment. FIG. 8 is a perspective view of the electric drive device according to the first embodiment with the cover removed. FIG. 9 is a perspective view of the back side of the cover according to the first embodiment. FIG. 10 is a plan view of the electric drive device according to the first embodiment with the circuit board removed. FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. 6. FIG. 12 is a cross-sectional view showing an enlarged partial cross-section of FIG. 11. FIG. 13 is a cross-sectional view taken along the line XII-XII in FIG. 6. As shown in FIGS. 6 and 7, the electric drive device 1 includes a motor 30 and an ECU 10 arranged on the anti-load side of the motor 30.

[0057] As shown in Figures 6 and 7, the ECU 10 includes a flange portion 40 and a cover 50 that covers the anti-load side of the motor 30. As shown in Figures 6 and 7, the cover 50 is fixed by being sandwiched between the flange portion 40 and the head of a bolt CT, which is a fixing member. As shown in Figures 8, 10, and 11, the flange portion 40 protrudes radially outward beyond the inner wall of the housing 930. In the embodiment, the flange portion 40 is formed integrally with the housing 930, but it may also be possible for the flange portion 40 to be separate from the housing 930, and for the flange portion 40 and the housing 930 to be fixed together with bolts or the like.

[0058] As shown in Fig. 6, a connector CNT is attached to the load side of the flange portion 40. The connector CNT is electrically connected to the circuit board 20. The connector CNT has terminals CNTP of the connector CNT including a power supply terminal, a communication terminal for performing CAN communication, and an input / output terminal for inputting and outputting data by a method other than CAN communication. The resin material of the connector CNT is, for example, polybutylene terephthalate (PBT). The terminals CNTP of the connector CNT are electrically connected to the circuit board 20.

[0059] As shown in Fig. 8, the flange portion 40 supports the circuit board 20 via a bearing holder 60 and a bolt BT1. The bolt BT1, which is a fixing member shown in Fig. 10, passes through a positioning portion 69 of the bearing holder 60 and is fastened to a female thread portion (not shown) formed in the flange portion 40. As shown in Figs. 8 and 10, the bearing holder 60 is fixed by being sandwiched between the flange portion 40 and the head of the bolt BT2.

[0060] The flange portion 40 has a base portion 41, a flange upper surface 41F (first surface), a groove portion 42, three position restriction portions 43, and a protrusion portion 45. The flange upper surface 41F (first surface), the groove portion 42, and the protrusion portion 45 are each annular, and are arranged so as to surround the outside of the circuit board 20 and the bearing holder 60. The protrusion portion 45, the groove portion 42, and the flange upper surface 41F (first surface) are arranged from the radially inner side to the radially outer side.

[0061] The protrusion 45 is an annular wall that protrudes toward the anti-load side from the base 41. The top of the protrusion 45 on the anti-load side is a plane that is perpendicular to the axial direction AX.

[0062] 10 and 11, the size of the bearing holder 60 when viewed in the axial direction AX is such that it can fit inside the support portion 52 of the lid 50. As shown in FIG. 11, the edge of the bearing holder 60 is positioned so that it overlaps the upper surface of the protrusion 45. This eliminates the need to seal between the bearing holder 60 and the lid 50, and between the bearing holder 60 and the flange 40. In the electric drive unit 1 of the first embodiment, it is sufficient to seal between the flange upper surface 41F and the edge portion 51 of the lid 50.

[0063] The flange upper surface 41F is an opposing surface facing the edge lower surface 51F (second surface) of the edge portion 51 of the lid 50. The flange upper surface 41F is a plane perpendicular to the axial direction AX. Over most of the flange upper surface 41F, the radial length of the flange upper surface 41F is greater than the radial length of the top of the protrusion 45 on the anti-load side.

[0064] The groove 42 is provided between the flange upper surface 41F and the protruding portion 45 and between the position restricting portion 43 and the protruding portion 45, and is an annular recess recessed below the flange upper surface 41F.

[0065] The position restricting portion 43 is an island-shaped portion on the flange upper surface 41F that protrudes from the flange upper surface 41F. The number of position restricting portions 43 is not limited to three, as long as there is more than one. The apex of the position restricting portion 43 on the anti-load side is a plane that is perpendicular to the axial direction AX. The apex of the position restricting portion 43 on the anti-load side is closer to the flange upper surface 41F than the apex of the protruding portion 45 on the anti-load side.

[0066] 8 supports the circuit board 20. The circuit board 20 is fixed to one surface (anti-load side) of the bearing holder 60. The flange portion 40 is made of a metal material with high heat dissipation properties, such as aluminum or copper, and also functions as a heat sink that transfers heat generated by electronic components mounted on the circuit board 20 to the flange portion 40.

[0067] 10 and 11, the first recess 63H, the second recess 64H, and the third recess 65H are recessed further than the surface on the anti-load side of the base 61 of the bearing holder 60. The first recess 63H is a recess whose longitudinal direction is arc-shaped when viewed in the axial direction AX.

[0068] The electrolytic capacitor 253 mounted on the first surface 21b of the circuit board 20 is inserted into the first recess 63H of the bearing holder 60. A heat dissipation material TM is applied between the circuit board 20 and the bottom surface (second heat-receiving surface) of the first recess 63H of the bearing holder 60. The heat dissipation material TM is, for example, a material obtained by mixing a thermally conductive filler with a silicone polymer, and is called a TIM (Thermal Interface Material). The heat dissipation material TM may be any material other than the above materials as long as it has a higher thermal conductivity than the board main body 21 of the circuit board 20. An end of a second electronic component other than the driving element 252 (for example, the electrolytic capacitor 253) is inserted inside the first recess 63H. Heat generated by the electrolytic capacitor 253 is transmitted to the bearing holder 60 via the heat dissipation material TM, thereby suppressing heat generation by the electrolytic capacitor 253.

[0069] For example, if the heat dissipation material TM is placed on the bottom surface (second heat receiving surface) of the first recess 63H at a depth that can cool at least 1 / 4 of the length of the axial direction AX of the electrolytic capacitor 253, the heat dissipation material TM can be interposed between the electrolytic capacitor 253 and the bottom surface (second heat receiving surface) of the first recess 63H even if manufacturing errors occur in the length and outer diameter of the electrolytic capacitor 253 in the axial direction AX, manufacturing errors in the thickness of the board body 21 of the circuit board 20, and assembly errors.

[0070] The second recess 64H is an arc-shaped recess that extends from the anti-load side surface of the base 61 of the bearing holder 60 toward the load side on an extension of the first recess 63H. The electrolytic capacitor 253 is not inserted into the second recess 64H. The second recess 64H reduces the volume of the base 61, contributing to a reduction in the weight of the electric drive unit 1.

[0071] The third recess 65H is located on an extension of the first recess 63H, between the first recess 63H and the second recess 64H. The third recess 65H is recessed from the anti-load side surface of the base 61 of the bearing holder 60 toward the load side, and is an arc-shaped recess with a longitudinal direction. The electrolytic capacitor 253 is not inserted into the third recess 65H. The third recess 65H reduces the volume of the base 61, contributing to a lighter weight of the electric drive device 1.

[0072] A thick portion 61A is present between the first recess 63H and the second recess 64H. A thick portion 61B is present between the second recess 64H and the third recess 65H. A thick portion 61C is present between the third recess 65H and the first recess 63H. The thick portions 61A, 61B, and 61C are thicker than the first recess 63H, the second recess 64H, and the third recess 65H. Due to the presence of the thick portions 61A, 61B, and 61C, the rigidity of the entire bearing holder 60 is ensured even when the first recess 63H, the second recess 64H, and the third recess 65H are provided, and the bearing holder 60 can support the bearing 33 with high precision.

[0073] As shown in Figure 11, shaft 31 is rotatably supported by bearing 33 and bearing 34. Bearing 33 is interposed between cylindrical portion 68 of flange portion 40 and shaft 31. Bearing 33 is disposed inside cylindrical portion 68. Bearing 34 is interposed between housing 930 and shaft 31. In this way, bearing holder 60 fixes the outer ring of bearing 33 inside cylindrical portion 68.

[0074] The bolt BT1, which is a fixing member shown in Fig. 8, passes through the circuit board 20 and is fastened to a female thread FH1 formed in the support pillar shown in Fig. 10. The circuit board 20 is fixed by being sandwiched between the support pillar 66 of the bearing holder 60 and the head of the bolt BT1.

[0075] The lid 50 is made of metal and prevents foreign matter and moisture from entering the interior of the electric drive device 1. As shown in FIGS. 9 and 11 , the lid 50 has a top plate portion 55 and a support portion 52. As shown in FIG. 11 , the top plate portion 55 covers the circuit board 20. The support portion 52 is located radially outward of the top plate portion 55 and extends toward the flange portion 40 beyond the top plate portion 55, covering the side of the circuit board 20. The edge portion 51 is an end portion of the support portion 52 that faces the flange portion 40.

[0076] The top plate portion 55 has a first heat receiving surface 54 protruding toward the load side, a wall portion 53 surrounding the electronic components, and a storage portion 53R surrounded by the wall portion 53. The support portion 52 has a through hole 51H penetrating in the axial direction AX, and a bolt CT (see FIG. 7) is inserted into the through hole 51H.

[0077] 9 and 11, in order to dissipate heat generated by the circuit board 20, the first heat receiving surface 54 faces the circuit board 20. A heat dissipation material TM is applied between the drive element 252 of the circuit board 20 and the first heat receiving surface 54 of the lid 50. The heat generated by the drive element 252 is transmitted to the lid 50 via the heat dissipation material TM, thereby suppressing heat generation by the drive element 252.

[0078] 9 and 11, the end of the first electronic component (for example, electrolytic capacitor 259) other than drive element 252 is inserted inside wall portion 53. As shown in FIG. 11, a heat dissipation material TM is applied between circuit board 20 and the bottom surface (third heat receiving surface) of reservoir 53R. Heat generated by electrolytic capacitor 259 is transferred to lid 50 via heat dissipation material TM, thereby suppressing heat generation by electrolytic capacitor 259.

[0079] The storage portion 53R has a ring-shaped wall portion 53 that surrounds the bottom surface (second heat receiving surface) of the storage portion 53R and protrudes further toward the load side than the bottom surface (second heat receiving surface) of the storage portion 53R. This makes it easier to hold the heat dissipation material TM, stabilizing heat dissipation.

[0080] As shown in FIG. 8, the circuit board 20 includes a board body 21 and a plurality of electronic components mounted on the board body 21. The board body 21 is, for example, a printed circuit board made of resin or the like. The circuit board 20 is a multilayer board having a plurality of conductive layers provided therein, and is a double-sided mounting board that allows for double-sided mounting. The plurality of electronic components mounted on one board body 21 include, for example, a central processing unit (CPU), an application specific integrated circuit (ASIC), a field effect transistor (FET), a magnetic sensor, an electrolytic capacitor, a resistor, a diode, a thermistor, and the like. These plurality of electronic components form the detection circuit 23, the control circuit 24, the first power circuit 25A, and the second power circuit 25B shown in FIG. 5.

[0081] For example, as shown in Fig. 8, a plurality of drive elements 252, a first motor drive circuit 26A, a second motor drive circuit 26B, an electrolytic capacitor 259, a choke coil 91, a capacitor 92, etc. are mounted on the anti-load side of the circuit board 20. The electrolytic capacitor 259 is connected to the boost circuit 245 (Fig. 5) to form a switched capacitor circuit. Here, as shown in Fig. 11, the load side of the circuit board 20 is the first surface 21b (the surface on the load side), and the anti-load side of the circuit board 20 is the second surface 21a (the surface on the anti-load side).

[0082] The detection circuit 23, the control circuit 24, the first power circuit 25A, and the second power circuit 25B shown in Fig. 5 are configured with one or more electronic components mounted on the first surface 21b or the second surface 21a. For example, as shown in Fig. 11, the detection circuit 23 is configured with one electronic component mounted on the first surface 21b of the substrate main body 21.

[0083] 5 is configured with a plurality of electronic components mounted on the second surface 21a of the substrate body 21. Furthermore, as shown in FIG. 11, the circuit board 20 includes an electrolytic capacitor 253 mounted on the second surface 21a of the substrate body 21.

[0084] The detection circuit 23 is disposed on the anti-load side of the shaft 31, on an extension of the axial direction AX of the magnet 32. The substrate body 21 has a plane perpendicular to the axial direction AX as its mounting surface for the detection circuit 23. The rotation angle sensor 23a (see FIG. 5) of the detection circuit 23 is mounted within the detection circuit 23 so as to be able to sense changes in the magnetic field of the magnet 32. It is desirable that the magnet 32 ​​and the rotation angle sensor 23a face each other in the axial direction AX. The rotation angle sensor 23a may be disposed on the second surface 21a instead of the first surface 21b of the substrate body 21, or may be disposed on both the first surface 21b and the second surface 21a of the substrate body 21.

[0085] The rotation angle sensor 23a is, for example, a spin valve sensor. A spin valve sensor is an element in which a non-magnetic layer is sandwiched between a pinned layer of a ferromagnetic material, the magnetization direction of which is fixed by an antiferromagnetic layer or the like, and a free layer of a ferromagnetic material, and is a sensor that can detect changes in the direction of magnetic flux. Spin valve sensors include GMR (Giant Magneto Resistance) sensors and TMR (Tunnel Magneto Resistance) sensors. Note that the rotation angle sensor 23a may be any sensor that can detect the rotation of the magnet 32. The rotation angle sensor 23a may be, for example, an AMR (Anisotropic Magneto Resistance) sensor or a Hall sensor.

[0086] As shown in FIG. 8, the electric drive device 1 includes first coil wiring 321 that connects the first coil group Gr1 (see FIG. 3) to the circuit board 20, and second coil wiring 322 that connects the second coil group Gr2 (see FIG. 3) to the circuit board 20. The first coil wiring 321 and the second coil wiring 322 may be included in the ECU 10 or may be included in the motor 30. The first coil wiring 321 and the second coil wiring 322 are inserted into through holes in the circuit board 20, and the circuit board 20 is electrically connected to the first coil wiring 321 and the second coil wiring 322. Note that the first coil wiring 321 and the second coil wiring 322 are omitted from FIG. 11.

[0087] 8, a connector CNT is attached to the load side of the flange portion 40. The connector CNT includes a first connector terminal PPW that supplies power, a second connector terminal PCN that serves as a communication terminal for performing CAN communication, and a third connector terminal PTS that serves as a communication terminal for inputting and outputting data by a method other than CAN communication.

[0088] As shown in Fig. 11, the motor 30 includes a housing 930. The motor rotor 932 includes a rotor yoke 932a and a magnet 932b. The magnet 932b is provided on the outer peripheral surface of the rotor yoke 932a. The housing 930 is cylindrical and accommodates therein the motor rotor 932, a stator including a plurality of coil groups divided into two systems for each three phase, for example, a first coil group Gr1 and a second coil group Gr2 (see Fig. 3), and the shaft 31.

[0089] As shown in Figures 10 and 11, a magnet 32 ​​is attached to one end of the shaft 31 via a magnet holder 32A. Half of the magnet 32 ​​is magnetized as a south pole when viewed from the axial direction AX, and the other half is magnetized as a north pole. Alternatively, the magnet 32 ​​may have south and north poles arranged alternately on its outer surface when viewed in the circumferential direction. Because the bearing 33 has high component precision, the position of the magnet 32, which is located on the anti-load side of the flange portion 40, in the axial direction AX is constant. The end where the magnet 32 ​​is located is the anti-load end of the shaft 31.

[0090] 11, the other end of the shaft 31 is provided with a motor gear 31G that transmits rotation to the worm shaft (see FIG. 2) of the reduction gear 175. The end of the shaft 31 at which the motor gear 31G is provided is the load side end of the shaft 31.

[0091] Fig. 11 is a cross-sectional view taken along the line XI-XI in Fig. 6. Fig. 12 is a cross-sectional view showing an enlarged partial cross-section of Fig. 11. Fig. 13 is a cross-sectional view taken along the line XII-XII in Fig. 6.

[0092] As shown in Fig. 11, when the lid 50 and the flange 40 are fitted together, the edge 51 is located radially outward of the protrusion 45. As shown in Fig. 12, the flange upper surface 41F and the edge lower surface 51F (second surface) of the edge 51 of the lid 50 face each other and are fixed together with a maximum distance 49D between them. The outer side surface 45S of the protrusion 45 and the inner side surface 51S of the edge 51 face each other and are fixed together with a maximum distance 45D between them. The maximum distance 45D is smaller than the maximum distance 49D.

[0093] As shown in Figure 13, the top of the position restricting portion 43 and the edge lower surface 51F (second surface) of the edge portion 51 of the lid 50 are in contact. The height from the flange upper surface 41F to the top of the position restricting portion 43 is a distance 43D. The outer side surface 45S of the protrusion 45 and the inner side surface 51S of the edge portion 51 face each other and are fixed in place while being separated by a maximum distance 45D. The distance 43D is the same as the maximum distance 49D.

[0094] When the bolt CT is fastened to the female thread 44, the cover 50 and the flange 40 are fixed together. This causes the top of the position restricting portion 43 to abut against the edge lower surface 51F, restricting the position of the edge lower surface 51F relative to the flange upper surface 41F. As a result, the distance 43D and the maximum distance 49D become approximately equal, and the maximum distance 49D tends to be constant around the flange 40.

[0095] As shown in Figures 12 and 13, a foam-in-place gasket 49 is filled between the edge portion 51 and the flange portion 40. The foam-in-place gasket 49 is also called a liquid gasket, and is paste-like and shape-changeable when uncured, and when cured, it becomes elastic and its outer shape is fixed. The cured foam-in-place gasket 49 becomes a sealing material that is waterproof and dustproof against external moisture and dust. The cured foam-in-place gasket 49 can prevent the intrusion of moisture and dust.

[0096] The flange portion 40 has a base portion 41, a protruding portion 45, a flange upper surface 41F (first surface), a position restricting portion 43, and a groove portion 42. The base portion 41 is a portion that protrudes radially outward from the motor 30. The protruding portion 45 protrudes from the base portion 41 toward the anti-load side and protrudes continuously in an annular shape when viewed in the axial direction AX. The flange upper surface 41F is provided radially outward from the protruding portion 45 and faces the cover 50. The multiple position restricting portions 43 are island-shaped convex portions that protrude from the first surface on the flange upper surface 41F toward the anti-load side. The groove portion 42 is provided annularly along the protruding portion when viewed in the axial direction, and is provided between the flange upper surface 41F and the protruding portion 45 and between the position restricting portion 43 and the protruding portion 45, and is a portion that is recessed from the flange upper surface 41F.

[0097] The cover 50 has a top plate 55, a support portion 52, and an edge portion 51. The support portion 52 is radially outward of the top plate 55 and extends further toward the load side than the top plate 55. The edge portion 51 is radially outward of the protrusion 45. The edge portion 51 of the cover 50 has an edge lower surface 51F (second surface) facing the flange upper surface 41F and a radially inner edge side surface 51S facing the radially outer side surface 45S of the protrusion 45. The form-in-place gasket 49 seals the groove 42, the gap between the flange upper surface 41F and the edge lower surface 51F, and the gap between the outer side surface 45S of the protrusion 45 and the edge inner side surface 51S. The bolt CT fastens the edge portion 51 to the position restricting portion 43 with the edge lower surface 51F contacting the position restricting portion 43.

[0098] This makes it easy to fit the lid 50 onto the flange 40. Furthermore, the edge 51 of the lid 50 can be positioned relative to the flange 40 without the form-in-place gasket 49 easily coming into contact with the position restricting portion 43. As a result, the assembly work of attaching the lid 50 to the flange 40 is made easier, and the form-in-place gasket 49 provides waterproofing to the electric drive unit 1.

[0099] The maximum distance 45D between the outer side surface 45S of the protrusion 45 and the inner side surface 51S of the rim 51 is smaller than the maximum distance 49D between the flange upper surface 41F and the rim lower surface 51F, so that the uncured foam-in-place gasket 49 expands in a direction that improves waterproofing.

[0100] Fig. 14 is a plan view illustrating a state in which electronic components are mounted on a second surface of the circuit board according to embodiment 1. Fig. 15 is a plan view illustrating a state in which electronic components are mounted on a first surface of the circuit board according to embodiment 1. The first connector terminal PPW (see Fig. 8) is electrically connected to the first connection region APW of the circuit board 20 shown in Figs. 14 and 15. The second connector terminal PCN (see Fig. 8) is electrically connected to the second connection region ACN of the circuit board 20 shown in Figs. 14 and 15. The third connector terminal PTS (see Fig. 8) is electrically connected to the third connection region ATS of the circuit board 20 shown in Figs. 14 and 15.

[0101] As shown in FIGS. 14 and 15, the board body 21 of the circuit board 20 has a first side 21s1, a second side 21s2, a third side 21s3, and a fourth side 21s4.

[0102] 14, a first connection region APW, a second connection region ACN, a third connection region ATS, and a power supply circuit region A90 are arranged at the edge of the fourth side 21s4. In the power supply circuit region A90, a power management circuit 27, a choke coil 91 that constitutes a noise filter circuit, and a plurality of capacitors 92 are arranged.

[0103] As shown in Figure 14, the edge of the first side 21s1 includes a first system connection area A321 to which the first coil wiring 321 (see Figure 8) is connected, a power supply circuit mounting area A256A in which the first system power supply circuit 256 (see Figure 5) is arranged, a power supply interruption circuit mounting area A255A in which the first system current interruption circuit 255 (see Figure 5) is arranged, a first inverter circuit mounting area A251A in which the first inverter circuit 251A (see Figure 5) is arranged, and a current element mounting area ASRA in which the first system shunt resistor SR (see Figure 5) is arranged.

[0104] As shown in Figure 14, the edge of the first side 21s1 is provided with a power supply circuit mounting area A256B where the second system power supply circuit 256 (see Figure 5) is arranged, a power supply interruption circuit mounting area A255B where the second system current interruption circuit 255 (see Figure 5) is arranged, a second inverter circuit mounting area A251B where the second inverter circuit 251B (see Figure 5) is arranged, and a current element mounting area ASRB where the second system shunt resistor SR (see Figure 5) is arranged.

[0105] As shown in FIG. 14, the edge of the first side 21s1 has a first system connection area A322 to which the second coil wiring 322 (see FIG. 8) is connected.

[0106] As shown in FIG. 14, an electrolytic capacitor 259, a first motor drive circuit 26A, or a second motor drive circuit 26B is disposed in the central portion of the board.

[0107] 15, the detection circuit 23 is disposed on an extension of the axial direction AX of the shaft 31. Here, in the board body 21 of the circuit board 20, a plurality of smoothing electrolytic capacitors 253 are arranged along an imaginary curve VC centered on a reference point on the extension of the axial direction AX of the shaft 31. The control arithmetic circuit 241 is disposed on the opposite side of the electrolytic capacitor 253 across the reference point on the extension of the axial direction AX of the shaft 31.

[0108] 14 and 15, the electrolytic capacitors 253 are disposed radially inward of the first inverter circuit mounting area A251A and the second inverter circuit mounting area A251B as viewed in the axial direction AX. As a result, the electrolytic capacitors 253 are adjacent to the first inverter circuit 251A and the second inverter circuit 251B and are not positioned to overlap with each other in the axial direction AX. This prevents the heat generated by the first inverter circuit 251A and the second inverter circuit 251B from overlapping with the heat generated by the electrolytic capacitors 253.

[0109] As shown in FIG. 11, when the circuit board 20 is attached to the bearing holder 60, the head of the electrolytic capacitor 253 is housed in the first recess 63H as shown in FIGS.

[0110] An imaginary line connecting the centers of the first recess 63H, the second recess 64H, and the third recess 65H in the width direction (radial direction) coincides with the curve VC described above. As a result, the multiple electrolytic capacitors 253 are accommodated side by side in the longitudinal direction of the first recess 63H. Because adjacent electrolytic capacitors 253 are spaced apart, heat is dispersed and does not concentrate between them.

[0111] 10 , when the arrangement of the plurality of electrolytic capacitors 253 is grasped by drawing a first imaginary line XVL that passes through a reference point on an extension of the axial direction AX of the shaft 31 and divides the plurality of electrolytic capacitors 253 in half, and a second imaginary line YVL that is perpendicular to the first imaginary line XVL and passes through a reference point on an extension of the axial direction AX of the shaft 31, the angle between the farthest electrolytic capacitor 253 and the reference point is equal to or greater than 90 degrees and less than 180 degrees. This makes it less likely that the electrolytic capacitors 253 will hit the thick portions 61A and 61C when the circuit board 20 is attached to the bearing holder 60, improving the ease of assembly.

[0112] As described above, the electric drive device 1 according to the first embodiment includes the motor 30 and the ECU 10 provided on the anti-load side of the shaft 31 for driving and controlling the motor 30. The ECU 10 includes the magnet 32 ​​at the end of the shaft 31 on the anti-load side, and the circuit board 20 arranged on the anti-load side of the shaft 31, on an extension of the axial direction of the shaft 31 (for example, the axial direction AX). The circuit board 20 has a detection circuit 23 including a rotation angle sensor 23a that detects rotation of the magnet 32 ​​(shaft 31). The rotation angle sensor 23a is a magnetic sensor that detects rotation of the magnet 32.

[0113] The ECU 10 includes a circuit board 20, a metal cover 50 that covers the circuit board 20, a form-in-place gasket 49, and a plurality of bolts CT for fastening the flange portion 40 and the cover 50 together.

[0114] The circuit board 20 has a driving element 252 of an inverter circuit 251 that drives a motor stator, and the top plate 55 of the lid 50 has a first heat receiving surface 54 that receives heat from the driving element 252 via a heat dissipation material TM. This allows the heat from the driving element 252, which generates a large amount of heat, to be transferred to the metal lid 50, suppressing a rise in temperature of the driving element 252.

[0115] The ECU 10 includes a bearing holder 60 that holds a bearing 33 that rotatably supports the shaft 31. The bearing holder 60 is disposed between the motor rotor 932 and the circuit board 20 in the axial direction AX, and is fixed to the flange portion 40. The circuit board 20 has a plurality of electrolytic capacitors 253, which are second electronic components other than the driving element 252, on its load-side surface.

[0116] The bearing holder 60 has a bottom surface (second heat receiving surface) of the first recess 63H of the bearing holder 60 that receives heat from the electrolytic capacitor 253 via the heat dissipation material TM. This makes it possible to suppress the overall heat generation of the circuit board 20 even if the mounting density of electronic components on the circuit board 20 is increased, thereby enabling the circuit board 20 and the electric drive device 1 themselves to be made smaller.

[0117] The multiple electrolytic capacitors 253 are arranged along a curve VC centered on a reference point on an extension of the axial direction AX of the shaft 31, as viewed in the axial direction AX, and are housed in first recesses 63H that are aligned along the curve VC. This makes it less likely that the electrolytic capacitors 253 will come into contact with the bearing holder 60 when the circuit board 20 is attached to the bearing holder 60, improving assembly workability. Furthermore, even if the attachment position of the circuit board 20 is determined by swinging the circuit board 20 around the reference point on an extension of the axial direction AX of the shaft 31, the electrolytic capacitors 253 are less likely to come into contact with the bearing holder 60, improving the degree of freedom in attaching the circuit board 20.

[0118] The electric power steering device 100 includes the electric drive device 1 described above, and the electric drive device 1 generates an auxiliary steering torque. This suppresses torque ripple in the motor 30, improving the operability of the electric power steering device 100.

[0119] (Embodiment 2) 16 is a schematic diagram of an electric power steering device according to embodiment 2. Note that the same components as those described in the above-mentioned embodiment 1 and embodiment 2 are given the same reference numerals, and redundant description will be omitted.

[0120] As shown in Fig. 16, the electric power steering device 100A is of a rack-parallel type. The shaft 31 of the motor 30 is connected to a power transmission mechanism 173. The power transmission mechanism 173 has a pulley 176 and a belt 177. The rotation of the belt 177 rotates a nut of a ball screw device 178. As a result, an assist force is applied to the rack shaft 199C based on the rotation of the shaft 31 of the motor 30.

[0121] (Embodiment 3) Fig. 17 is a schematic diagram of an electric power steering device according to a third embodiment. Note that the same components as those described in the first and second embodiments are given the same reference numerals, and redundant description will be omitted. The electric power steering device 100B shown in Fig. 17 is of a pinion assist type that applies an assist steering torque to a first pinion shaft 199A. In the electric power steering device 100B, a torque sensor 194 is connected to the first pinion shaft 199A.

[0122] The motor 30 rotates the worm shaft reduction gear 175. The worm wheel of the reduction gear 175 rotates integrally with the first pinion shaft 199A. This allows the motor 30 to rotate the first pinion gear 199B. The first pinion gear 199B meshes with the first rack 199D. As a result, the electric drive unit 1 applies an assist force to the first rack 199D via the reduction gear 175. The first pinion gear 199B may be disposed orthogonal to the first rack 199D, or may be disposed obliquely away from the orthogonal orientation. As described above, the electric power steering device 100B of the third embodiment is of a single-pinion assist type.

[0123] (Embodiment 4) Fig. 18 is a schematic diagram of an electric power steering device according to a fourth embodiment. Note that the same components as those described in the first to third embodiments are assigned the same reference numerals, and redundant description will be omitted. The electric power steering device 100C includes an output shaft 192B and a second pinion gear 171B in addition to a first pinion shaft 199A and a first pinion gear 199B. The electric power steering device 100C is of a dual pinion assist type. A torque sensor 194 detects the torque between a pinion shaft 195 and a first pinion gear 199B.

[0124] The motor 30 rotates the reduction gear 175 of the worm shaft. The worm wheel of the reduction gear 175 rotates integrally with the output shaft 192B. This allows the motor 30 to rotate the second pinion gear 171B. The second pinion gear 171B meshes with the second rack 171C. As a result, the electric drive unit 1 applies an assist force to the second rack 171C via the reduction gear 175. The second pinion gear 171B may be disposed orthogonal to the second rack 171C, or may be disposed obliquely away from the orthogonal orientation. The electric power steering device 100C of the fourth embodiment is of a dual pinion assist type. [Explanation of symbols]

[0125] 1 Electric drive unit 10 ECU 20 Circuit Board 21 Board body 21a 2nd side 21b 1st page 21s1 Side 1 21s2 Second side 21s3 Third side 21s4 4th side 23 Detection circuit 23a Rotation angle sensor 23b Sensor control unit 24 Control circuit 25A 1st power circuit 25B Second power circuit 26A First motor drive circuit 26B Second motor drive circuit 27 Power management circuit 30 motor 31 Shaft 32 Magnet 37 First coil 38 Second coil 40 flange 41 Base 41F Flange top surface 42 Groove 43 Position regulation part 44 Female thread 45 Protrusion 50 Lid 51 Edge 51F lower edge 51S inner side 52 Support part 53 Wall 53R storage section 54 1st heat receiving surface 55 Top plate 60 Bearing holder 61 Base 61A, 61B, 61C Thick part 63H First recess 64H 2nd recess 65H 3rd recess 100, 100A, 100B, 100C Electric power steering device 251 Inverter Circuit 252 driving element 253, 259 Electrolytic capacitors 930 Housing 931 stator core 932 Motor rotor A251A 1st inverter circuit mounting area A251B Second inverter circuit mounting area A255A Power Cutoff Circuit Mounting Area A255B Power cutoff circuit mounting area A256A Power supply circuit mounting area A256B Power supply circuit mounting area A321 1st Line Connection Area A322 1st Line Connection Area A90 Power supply circuit area ACN Second Connection Area APW 1st connection area ASRA current element placement area ASRB current element placement area ATS 3rd connection area AX Axial direction BT1, BT2, CT bolts CNT Connector Gr1 1st coil group Gr2 Second coil group TM heat dissipation material

Claims

1. An electric drive device comprising a motor and an electronic control device that controls the rotation of the motor, The motor a shaft extending in an axial direction from a load side to a non-load side; a motor rotor coupled to the shaft; a motor stator that rotates the motor rotor; a housing that accommodates the motor rotor and the motor stator therein; a flange portion provided on the anti-load side of the housing; a magnet provided on the anti-load side of the shaft; a bearing that rotatably supports the shaft; a bearing holder for supporting the bearing; Including, The electronic control device A circuit board; a metal cover that covers the circuit board; Including, The circuit board includes: A board body that can be mounted on both sides, a plurality of smoothing electrolytic capacitors arranged on a first surface of the substrate body on the load side; a driving element of an inverter circuit mounted on a second surface of the substrate body on the opposite side to the load side and driving the motor stator; a detection circuit that is located on an extension line of the magnet in the axial direction and is attached to the substrate body, and that detects rotation of the shaft; Including, The lid body is The top plate and the cover has a first heat receiving surface that receives heat from the drive element via a heat dissipation material; Including, The bearing holder includes: a base of the bearing holder; a first recessed portion recessed from a surface on the anti-load side of the base portion of the bearing holder toward the load side and having an arc-shaped longitudinal direction, at a position radially outward of the bearing as viewed in the axial direction; Including, the plurality of electrolytic capacitors are arranged along a curve having a center at a reference point on an extension line of the shaft in the axial direction, as viewed in the axial direction; The plurality of electrolytic capacitors are accommodated in the first recess. Electric drive unit.

2. Adjacent electrolytic capacitors are spaced apart, the angle between the farthest electrolytic capacitor and the reference point is equal to or greater than 90 degrees and less than 180 degrees; The electric drive device according to claim 1 .

3. a second recess having an arc-shaped longitudinal direction, recessed from the anti-load side surface of the base of the bearing holder toward the load side, on an extension line of the first recess as viewed in the axial direction; The electric drive device according to claim 1 .

4. a third recess portion having an arc-shaped longitudinal direction and recessed from a surface of the anti-load side of the base portion of the bearing holder toward the load side, between the first recess portion and the second recess portion as viewed in the axial direction; a thick portion is provided between the first recess and the second recess, between the second recess and the third recess, and between the third recess and the first recess, The electric drive device according to claim 3 .

5. the motor stator includes a stator core that rotates the motor rotor, and a plurality of coil groups that are divided into at least two systems of first coil groups and second coil groups for each of three phases, and that excite the stator core with three-phase AC; The circuit board includes: the second surface includes a first inverter circuit mounting area for mounting a first inverter circuit that supplies current to the first coil group, and a second inverter circuit mounting area for mounting a second inverter circuit that supplies current to the second coil group, the first inverter circuit mounting region is disposed on an edge of a first side of the circuit board; the second inverter circuit mounting area is adjacent to the first side and is disposed on an edge of a second side in a direction different from the first side; the plurality of electrolytic capacitors are arranged radially inside the first inverter circuit mounting area and the second inverter circuit mounting area; 2. The electric drive device according to claim 1.

6. The electric drive device according to any one of claims 1 to 5, An electric power steering device in which the electric drive device generates an auxiliary steering torque.

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