JP7400655B2 - Electric drive device and electric power steering device - Google Patents

Description

The present invention 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.

An electric power steering device that uses a motor to generate auxiliary steering torque includes an electronic control device that controls the motor. For example, Patent Document 1 describes a drive device that can mount electronic components on a board with high density.

Japanese Patent Application Publication No. 2016-034204 JP2007-288929A JP2017-092100A

In the electric drive device of Patent Document 1, the motor, the electronic control device, and the connector are arranged in this order along an axial direction parallel to the shaft of the motor. Since the direction of insertion into and removal from the connector is the axial direction, the electric drive device of Patent Document 1 increases in size in the axial direction.

On the other hand, in the electric drive devices of Patent Document 2 and Patent Document 3, the direction of insertion into and removal from the connector is the radial direction of the shaft of the motor. As a result, the electric drive device of Patent Document 2 and Patent Document 3 has a smaller axial size than the electric drive device of Patent Document 1.

In the electric drive device of Patent Document 2 and Patent Document 3, the terminal of the connector is electrically connected to the board. The power supplied from the terminal is supplied to a power circuit including a field effect transistor (FET) that supplies current to the coil group via a power supply wiring in the board. As the electric power for driving the motor becomes larger, the power supply wiring within the board needs to be made larger, and the area of the board becomes larger (see Patent Document 3 [0015], FIG. 2). Therefore, there is a demand for an electric drive device in which the shaft of the motor is small in the radial direction.

Therefore, the inventor of the present application decided to suppress the size in the axial direction parallel to the motor shaft and in the radial direction of the shaft by attaching the circuit board to the bus bar module integrated with the connector. Here, when the busbar module is housed in the heatsink, the relative positions of the circuit board, the busbar module, and the heatsink may vary. Variations in the relative positions of the circuit board, busbar module, and heat sink affect the relative positions of the magnet attached to the shaft and the rotation angle sensor mounted on the circuit board, resulting in a decrease in the accuracy of shaft rotation angle detection. there is a possibility.

The present invention has been made in view of the above-mentioned problems, and can increase the detection accuracy of the rotation angle of the shaft while suppressing the size in the axial direction parallel to the shaft of the motor and the radial direction of the shaft. The purpose of the present invention is to provide an electric drive device and an electric power steering device.

To achieve the above object, an electric drive device according to one embodiment includes: a shaft extending in the axial direction from a load side to a counter-load side; a motor rotor interlocking with the shaft; a motor stator that rotates the motor rotor; and a cylindrical housing that houses the motor stator therein, a magnet provided at the end of the shaft on the opposite load side, an electronic control device including a circuit board, and a connector. A first power terminal, a second power terminal, a positive bus bar wiring that electrically connects the connector and the first power terminal, and a negative bus bar wiring that electrically connects the connector and the second power terminal. and a bus bar module having a through hole into which the shaft is inserted, a hollow portion through which the shaft passes, a first surface provided on the opposite load side, and a bus bar module erected on the first surface. a heat sink having a first positioning pin and a second positioning pin, and a bearing disposed in the hollow part of the heat sink and supporting the shaft; a rotation angle sensor that is disposed on the load side of the main body and detects rotation of the magnet, and the housing, the heat sink, the bus bar module, and the circuit board are arranged in this order in the axial direction, The rotation angle sensor faces the magnet, the first positioning pin and the second positioning pin penetrate the busbar module and the circuit board, respectively, and the rotation angle sensor faces the magnet, and the first positioning pin and the second positioning pin penetrate the busbar module and the circuit board, respectively. The first locating pin, the shaft, and the second locating pin are aligned on a straight line.

As a result, the size of the motor in the axial direction parallel to the shaft and in the radial direction of the shaft is suppressed, and the electric drive device becomes smaller. Since the first positioning pin and the second positioning pin pass through the busbar module and the circuit board, even if the busbar module is housed in the heat sink, the relative positions of the circuit board, the busbar module, and the heat sink will be the same as those of the first positioning pin. and a second positioning pin. This reduces variations in the relative positions of the circuit board, bus bar module, and heat sink. As a result, the accuracy of the relative position of the magnet attached to the shaft and the rotation angle sensor mounted on the circuit board increases, so the detection accuracy of the rotation angle of the shaft increases.

As a desirable aspect, the first positioning pin, the rotation angle sensor, and the second positioning pin are aligned in a straight line when viewed in the axial direction. This increases the accuracy of the relative position of the rotation angle sensor mounted on the circuit board.

As a desirable aspect, the first positioning pin and the second positioning pin are arranged at positions sandwiching the shaft when viewed in the axial direction. This disperses the stress of fixing the busbar module to the heatsink, making it difficult for the busbar module to move relative to the heatsink. The stress of fixing the circuit board to the heat sink is dispersed, making it difficult for the busbar module to move relative to the heat sink.

As a desirable aspect, the first positioning pin and the second positioning pin protrude beyond the circuit board from the load side to the anti-load side. This makes it easier to guide the first positioning pin and the second positioning pin to the through hole of the circuit board.

In a desirable aspect, the heat sink has a raised part having a second face raised from the first face, and a first protrusion and a second protrusion that protrude from the first face toward the anti-load side, When the busbar module is housed in the step between the first surface and the second surface, the busbar module and the first convex portion are brought into contact with each other and fixed, and the load side is lowered from the load side than the second surface. The second convex portion protruding toward the opposite load side and the circuit board are in contact with and fixed to each other. As a result, the contact area between the busbar module and the heat sink is made small, and even if the molding tolerance of the busbar module is larger than the shape processing tolerance of the heat sink, the mounting position of the busbar module with respect to the heat sink is less affected by the molding tolerance. Further, since a gap is created between the circuit board and the heat sink, the heat dissipating material is easily held in the gap.

In a desirable aspect, the through hole of the circuit board through which the first positioning pin passes has a length in a radial direction that is larger than a length in a direction perpendicular to the radial direction. This increases the clearance between the first positioning pin and the through hole of the circuit board, and the first positioning pin and the second positioning pin do not pinch the circuit board in a state where stress is applied to the circuit board. As a result, the circuit board is not distorted, the rotation angle sensor is less likely to be misaligned in the axial direction, and the detected values of the rotation angle sensor are less likely to vary. Then, the detection accuracy of the rotation angle sensor becomes higher.

In a desirable embodiment, the electric power steering device includes an electric drive device, and the electric drive device generates an auxiliary steering torque. As a result, the size of the motor in the axial direction parallel to the shaft and the radial direction of the shaft is suppressed, and the degree of freedom in the arrangement of the electric power steering device is improved.

According to the present invention, there is provided an electric drive device and an electric power steering device that can increase the detection precision of the rotation angle of the shaft while suppressing the size in the axial direction parallel to the shaft of the motor and the radial direction of the shaft. be able to.

FIG. 1 is a perspective view schematically showing a vehicle equipped with an electric power steering device according to an embodiment. FIG. 2 is a schematic diagram of the electric power steering device according to the embodiment. FIG. 3 is a side view showing an example of the arrangement of the ECU according to the embodiment. FIG. 4 is a sectional view schematically showing a cross section of the motor according to the embodiment. FIG. 5 is a schematic diagram showing the wiring of the motor according to the embodiment. FIG. 6 is a schematic diagram showing the relationship between the motor and the ECU according to the embodiment. FIG. 7 is a perspective view showing a configuration example of the electric drive device according to the embodiment. FIG. 8 is an exploded perspective view showing a configuration example of the electric drive device according to the embodiment. FIG. 9A is a perspective view showing a configuration example of a busbar module according to an embodiment. FIG. 9B is an explanatory diagram showing an example of the internal configuration of FIG. 9A. FIG. 10A is a perspective view showing a configuration example of a busbar module, viewed from a different direction from FIG. 9A. FIG. 10B is an explanatory diagram showing an example of the internal configuration of FIG. 10A. FIG. 11 is a perspective view illustrating a state in which the busbar module is accommodated in the step of the heat sink. FIG. 12 is a top view illustrating a state in which the busbar module is accommodated in the step of the heat sink. FIG. 13 is a top view illustrating a state in which the busbar module is accommodated in the step of the heat sink and the circuit board is attached. FIG. 14 is a step view taken along line XIV-XIV in FIG. 13. FIG. 15 is an explanatory diagram for explaining the positional relationship between the shaft and the positioning pin. FIG. 16 is a perspective view for explaining the relationship between the arrangement of heat-generating electronic components on the circuit board and the second surface of the heat sink facing the electronic components. FIG. 17 is a cross-sectional view for explaining a partial cross-section of the electric drive device. FIG. 18 is an explanatory diagram showing the positional relationship between the permanent magnet, the first sensor, and the second sensor of this embodiment. FIG. 19 is a circuit diagram showing the circuit configuration of the sensor chip of this embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

FIG. 1 is a perspective view schematically showing a vehicle equipped with an electric power steering device according to an embodiment. FIG. 2 is a schematic diagram of the electric power steering device according to the embodiment. 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 explained with reference to FIG. 2.

The electric power steering device 100 includes a steering wheel 91, a steering shaft 92, a universal joint 96, an intermediate shaft 97, a universal joint 98, and a first It includes a rack and pinion mechanism 99 and a tie rod 72. The electric power steering device 100 also includes a torque sensor 94 that detects the steering torque of the steering shaft 92, a motor 30, and an electronic control unit (hereinafter referred to as ECU (Electronic Control Unit)) 10 that controls the motor 30. It includes a speed reduction device 75 and a second rack and pinion mechanism 70. A vehicle speed sensor 82, a power supply device 83 (for example, a vehicle-mounted battery), and an ignition switch 84 are provided in the vehicle body. Vehicle speed sensor 82 detects the traveling speed of vehicle 101. The vehicle speed sensor 82 outputs the detected vehicle speed signal SV to the ECU 10 through CAN (Controller Area Network) communication. Electric power is supplied to the ECU 10 from the power supply device 83 while the ignition switch 84 is on.

The electric drive device 1 includes a motor 30 and an ECU 10 fixed to the opposite load side of the shaft 31 of the motor 30. Furthermore, the electric drive device 1 may include an adapter that connects the ECU 10 and the motor 30.

As shown in FIG. 2, the steering shaft 92 includes an input shaft 92A, an output shaft 92B, and a torsion bar 92C. The input shaft 92A has one end connected to the steering wheel 91 and the other end connected to the torsion bar 92C. The output shaft 92B has one end connected to the torsion bar 92C and the other end connected to the universal joint 96. Note that the torque sensor 94 detects the steering torque applied to the steering shaft 92 by detecting the twist of the torsion bar 92C. The torque sensor 94 outputs a steering torque signal T corresponding to the detected steering torque to the ECU 10 via CAN communication. The steering shaft 92 is rotated by the steering force applied to the steering wheel 91.

The intermediate shaft 97 has an upper shaft 97A and a lower shaft 97B, and transmits the torque of the output shaft 92B. Upper shaft 97A is connected to output shaft 92B via universal joint 96. On the other hand, the lower shaft 97B is connected to a first pinion shaft 99A of a first rack and pinion mechanism 99 via a universal joint 98. The upper shaft 97A and the lower shaft 97B are, for example, spline-coupled.

The first rack and pinion mechanism 99 includes a first pinion shaft 99A, a first pinion gear 99B, a rack shaft 99C, and a first rack 99D. The first pinion shaft 99A has one end connected to the lower shaft 97B via the universal joint 98, and the other end connected to the first pinion gear 99B. A first rack 99D formed on the rack shaft 99C meshes with a first pinion gear 99B. The rotational motion of the steering shaft 92 is transmitted to the first rack and pinion mechanism 99 via an intermediate shaft 97. This rotational motion is converted by the first rack and pinion mechanism 99 into linear motion of the rack shaft 99C. The tie rods 72 are connected to both ends of the rack shaft 99C.

The motor 30 is a motor that generates auxiliary steering torque to assist the driver in steering. The motor 30 may be a brushless motor or a brush motor having brushes and a commutator.

The ECU 10 includes a rotation angle sensor 23a. The rotation angle sensor 23a detects the rotation phase of the motor 30. ECU 10 acquires a rotation phase signal of motor 30 from rotation angle sensor 23a, a steering torque signal T from torque sensor 94, and a vehicle speed signal SV of vehicle 101 from vehicle speed sensor 82. The ECU 10 calculates an auxiliary steering command value of the assist command based on the rotational phase signal, the steering torque signal T, and the vehicle speed signal SV. The ECU 10 supplies current to the motor 30 based on the calculated auxiliary steering command value.

The speed reducer 75 includes a worm shaft 75A that rotates together with the shaft 31 of the motor 30, and a worm wheel 75B that meshes with the worm shaft 75A. Therefore, the rotational motion of shaft 31 is transmitted to worm wheel 75B via worm shaft 75A. In addition, in this embodiment, the side of the shaft 31 on the deceleration device 75 side is referred to as a load side end, and the side of the shaft 31 opposite to the deceleration device 75 is referred to as an anti-load side end.

The second rack and pinion mechanism 70 includes a second pinion shaft 71A, a second pinion gear 71B, and a second rack 71C. The second pinion shaft 71A is fixed such that one end thereof is coaxial with the worm wheel 75B and rotates together with the worm wheel 75B. The other end of the second pinion shaft 71A is connected to the second pinion gear 71B. The second rack 71C formed on the rack shaft 99C meshes with the second pinion gear 71B. The rotational motion of the motor 30 is transmitted to the second rack and pinion mechanism 70 via the speed reduction device 75. This rotational motion is converted into linear motion of the rack shaft 99C by the second rack and pinion mechanism 70.

The driver's steering force input to the steering wheel 91 is transmitted to the first rack and pinion mechanism 99 via the steering shaft 92 and intermediate shaft 97. The first rack and pinion mechanism 99 transmits the transmitted steering force to the rack shaft 99C as a force applied in the axial direction of the rack shaft 99C. At this time, the ECU 10 acquires the steering torque signal T input to the steering shaft 92 from the torque sensor 94. ECU 10 acquires vehicle speed signal SV from vehicle speed sensor 82. The ECU 10 acquires a 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 second rack and pinion mechanism 70 via the speed reduction device 75. The second rack and pinion mechanism 70 transmits the auxiliary steering torque to the rack shaft 99C as a force applied in the axial direction of the rack shaft 99C. In this way, the driver's steering of the steering wheel 91 is assisted by the electric power steering device 100.

As shown in FIG. 2, the electric power steering device 100 is of a rack assist type in which an assist force is applied to the second rack and pinion mechanism 70, but the present invention is not limited thereto. The electric power steering device 100 may be, for example, a column assist system in which the assist force is applied to the steering shaft 92, or a pinion assist system in which the assist force is applied to the first pinion gear 99B.

FIG. 3 is a side view showing an example of the arrangement of the ECU according to the embodiment. As shown in FIG. 3, the electric drive device 1 including the ECU 10 and the motor 30 is arranged in a speed reduction device 75. In the connector CNT shown in FIG. 3, a wire harness can be inserted and removed in parallel to the direction in which the rack shaft 99C shown in FIG. 2 extends. In this embodiment, the axial direction Ax refers to a direction parallel to the direction in which the shaft 31 of the motor 30 (see FIG. 4) extends. The axial direction Ax is often inclined with respect to the vertical direction VD. This is because the axial direction Ax is determined based on the space of the vehicle 101 (see FIG. 1).

FIG. 4 is a sectional view schematically showing a cross section of the motor according to the embodiment. FIG. 5 is a schematic diagram showing the wiring of the motor according to the embodiment. In this 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. 4, the motor 30 includes a housing 930, a motor stator having a stator core 931, and a motor rotor 932. The motor stator includes a cylindrical stator core 931, a plurality of first coils 37, and a plurality of second coils 38. Stator core 931 includes an annular back yoke 931a and a plurality of teeth 931b protruding from the inner peripheral surface of back yoke 931a. Twelve teeth 931b are arranged in the circumferential direction. 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 number of magnets 932b is, for example, eight. The rotation of the motor rotor 932 is interlocked with the rotation of the shaft 31.

As shown in FIG. 4, the first coil 37 is wound in a concentrated manner around each of the plurality of teeth 931b. The first coil 37 is concentratedly wound around the outer periphery of the teeth 931b via an insulator. All the first coils 37 are included in the first coil system. The first coil system according to the embodiment is supplied with current and excited by the inverter circuit 251 (see FIG. 6) 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 such that two first coils 37 are adjacent to each other in the circumferential direction. Three first coil groups Gr1 each including 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. Note that 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. Further, it is preferable that n be an odd number. As explained above, in this embodiment, there are a plurality of coil groups, and each of the three phases is divided into at least two systems, the first coil group gr1 and the second coil group Gr2, and the stator core is excited by three-phase alternating current. be done.

As shown in FIG. 4, the second coil 38 is wound in a concentrated manner around each of the plurality of teeth 931b. The second coil 38 is concentratedly wound around the outer periphery of the teeth 931b via an insulator. The teeth 931b around which the second coil 38 is wound in a concentrated manner are different from the teeth 931b around which the first coil 37 is wound in a concentrated manner. All second coils 38 are included in the second coil system. The second coil system is supplied with current and excited by the inverter circuit 251 (see FIG. 6) 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 such that two second coils 38 are adjacent to each other in the circumferential direction. Three second coil groups Gr2 each including 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. Note that the number of second coil groups Gr2 does not necessarily have to be three; it is sufficient that 3n pieces are arranged at equal intervals in the circumferential direction, where n is a natural number. Further, it is preferable that n be an odd number.

As shown in FIG. 5, the six first coils 37 include two first U-phase coils 37Ua and 37Ub that are excited by the first U-phase current I1u, and two first U-phase coils 37Ua and 37Ub that are excited by the first V-phase current I1v. It includes a first V-phase coil 37Va and a first V-phase coil 37Vb, and two first W-phase coils 37Wa and 37Wb that are excited by the first W-phase current I1w. The first U-phase coil 37Ub is connected in series to the first U-phase coil 37Ua. The first V-phase coil 37Vb is connected in series to the first V-phase coil 37Va. The first W-phase coil 37Wb is connected in series to the first W-phase coil 37Wa. The winding directions of the first coil 37 around the teeth 931b are all the same. Further, the first U-phase coil 37Ub, the first V-phase coil 37Vb, and the first W-phase coil 37Wb are connected by a star connection (Y connection).

As shown in FIG. 5, the six second coils 38 include two second U-phase coils 38Ua and a second U-phase coil 38Ub that are excited by the second U-phase current I2u, and two second U-phase coils 38Ua and 38Ub that are excited by the second V-phase current I2v. It includes a second V-phase coil 38Va and a second V-phase coil 38Vb, and two second W-phase coils 38Wa and two second W-phase coils 38Wb that are excited by the second W-phase current I2w. The second U-phase coil 38Ub is connected in series to the second U-phase coil 38Ua. The second V-phase coil 38Vb is connected in series to the second V-phase coil 38Va. The second W-phase coil 38Wb is connected in series to the second W-phase coil 38Wa. The winding directions of the second coils 38 around the teeth 931b are all the same, and are the same as the winding directions of the first coils 37. Further, the second U-phase coil 38Ub, the second V-phase coil 38Vb, and the second W-phase coil 38Wb are connected by a star connection (Y connection).

As shown in FIG. 4, the three first coil groups Gr1 include 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.

As shown in FIG. 4, the three second coil groups Gr2 include 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.

The first coil 37 excited by the first U-phase current I1u faces the second coil 38 excited by the second U-phase current I2u in the radial direction of the stator core 931. In the following description, the radial direction of stator core 931 is simply referred to as the radial direction. For example, as shown in FIG. 4, the first U-phase coil 37Ua faces the second U-phase coil 38Ua, and the first U-phase coil 37Ub faces the second U-phase coil 38Ub in the radial direction.

The first coil 37 excited by the first V-phase current I1v is radially opposed to the second coil 38 excited by the second V-phase current I2v. For example, as shown in FIG. 4, the first V-phase coil 37Va faces the second V-phase coil 38Va, and the first V-phase coil 37Vb faces the second V-phase coil 38Vb in the radial direction.

The first coil 37 excited by the first W-phase current I1w is radially opposed to the second coil 38 excited by the second W-phase current I2w. For example, as shown in FIG. 4, the first W-phase coil 37Wa faces the second W-phase coil 38Wa, and the first W-phase coil 37Wb faces the second W-phase coil 38Wb in the radial direction.

FIG. 6 is a schematic diagram showing the relationship between the motor and the ECU according to the embodiment. As shown in FIG. 6, the ECU 10 includes a detection circuit 23, a control circuit 24, a first power circuit 25A, and a second power circuit 25B. The detection circuit 23 includes a rotation angle sensor 23a and a motor rotation speed calculation section 23b. The control circuit 24 includes a control calculation section 241, a gate drive circuit 242, and a cutoff drive circuit 243. The first power circuit 25A includes an inverter circuit 251 and a current cutoff circuit 255. The second power circuit 25B includes an inverter circuit 251 and a current cutoff circuit 255. Further, the inverter circuit 251 includes a plurality of switching elements 252 and a current detection circuit 254 for detecting a current value. Note that in FIG. 6, circuits that do not require explanation are omitted as appropriate.

The control calculation unit 241 calculates a motor current command value. The motor rotation speed calculation unit 23b calculates the motor electrical angle θm and outputs it to the control calculation unit 241. The motor current command value output from the control calculation section 241 is input to the gate drive circuit 242 . The gate drive circuit 242 controls the first power circuit 25A and the second power circuit 25B based on the motor current command value.

As shown in FIG. 6, the ECU 10 includes a rotation angle sensor 23a. The rotation angle sensor 23a is, for example, a magnetic sensor. The detected value of the rotation angle sensor 23a is supplied to the motor rotation speed calculation section 23b. The motor rotation speed calculation unit 23b calculates the motor electrical angle θm based on the detected value of the rotation angle sensor 23a, and outputs it to the control calculation unit 241.

The control calculation unit 241 receives the steering torque signal T detected by the torque sensor 94, the vehicle speed signal SV detected by the vehicle speed sensor 82, and the motor electrical angle θm output from the motor rotation speed calculation unit 23b. be done. The control calculation unit 241 calculates a motor current command value based on the steering torque signal T, vehicle speed signal SV, and motor electrical angle θm, and outputs it to the gate drive circuit 242.

The gate drive circuit 242 calculates a first pulse width modulation signal based on the motor current command value and outputs it to the inverter circuit 251 of the first power circuit 25A. The inverter circuit 251 switches the switching element 252 so that the current values of three phases are obtained according to the duty ratio of the first pulse width modulation signal, so that a first U-phase current I1u, a first V-phase current I1v, and a first W-phase current are generated. A three-phase alternating current including current I1w is generated. The first U-phase current I1u excites the first U-phase coil 37Ua and the first U-phase coil 37Ub, the first V-phase current I1v excites the first V-phase coil 37Va and the first V-phase coil 37Vb, and the first W-phase current I1w excites the first U-phase coil 37Ua and the first U-phase coil 37Ub. Phase coil 37Wa and first W-phase coil 37Wb are excited.

The gate drive circuit 242 calculates a second pulse width modulation signal based on the motor current command value and outputs it to the inverter circuit 251 of the second power circuit 25B. The inverter circuit 251 switches the switching element 252 so that the current values of three phases are obtained according to the duty ratio of the second pulse width modulation signal, so that a second U-phase current I2u, a second V-phase current I2v, and a second W-phase current are generated. A three-phase alternating current including current I2w is generated. The second U-phase current I2u excites the second U-phase coil 38Ua and the second U-phase coil 38Ub, the second V-phase current I2v excites the second V-phase coil 38Va and the second V-phase coil 38Vb, and the second W-phase current I2w excites the second V-phase coil 38Va and the second V-phase coil 38Vb. The phase coil 38Wa and the second W-phase coil 38Wb are excited.

The inverter circuit 251 is a power conversion circuit that converts DC power to AC power. As described above, the inverter circuit 251 includes a plurality of switching elements 252. The switching element 252 is, for example, a field effect transistor. A smoothing capacitor 253 is connected in parallel to the inverter circuit 251 . The smoothing capacitor 253 is, for example, an electrolytic capacitor. The circuit board 20 includes a plurality of smoothing capacitors connected in parallel as smoothing capacitors 253 .

Furthermore, as described above, the inverter circuit 251 includes the current detection circuit 254. Current detection circuit 254 includes, for example, a shunt resistor. The current value detected by the current detection circuit 254 is sent to the control calculation section 241. Note that the current detection circuit 254 may be connected to detect the current value of each phase of the motor 30.

Current cutoff circuit 255 is arranged between inverter circuit 251 and first coil 37 or second coil 38. If the current value detected by the current detection circuit 254 is determined to be abnormal, the control calculation unit 241 drives the current cutoff circuit 255 via the cutoff drive circuit 243 to reduce the current flowing from the inverter circuit 251 to the first coil 37. can be blocked. Further, the control calculation unit 241 can drive the current cutoff circuit 255 via the cutoff drive circuit 243 to cut off the current flowing from the inverter circuit 251 to the second coil 38 . In this way, the current flowing to the first coil 37 and the current flowing to the second coil 38 are independently controlled by the control calculation unit 241. Further, input/output signals such as the steering torque signal T and the vehicle speed signal SV are transmitted to the control calculation unit 241 via the connector CNT.

FIG. 7 is a perspective view showing a configuration example of the electric drive device according to the embodiment. FIG. 8 is an exploded perspective view showing a configuration example of the electric drive device according to the embodiment. As shown in FIGS. 7 and 8, the electric drive device 1 includes a motor 30 and an ECU 10 disposed on the opposite load side of the motor 30. Motor 30 includes a housing 930. The housing 930 has a cylindrical shape, and has a stator inside thereof that includes a motor rotor 932 and a plurality of coil groups divided into two systems for each three phases, for example, a first coil group Gr1 and a second coil group Gr2 (see FIG. 4). and the shaft 31.

A magnet 32 is attached to the end of the shaft 31 on the anti-load side. When viewed from the axial direction Ax, half of the magnet 32 is magnetized as an S pole and half as an N pole. Alternatively, the magnet 32 may have S poles and N poles alternately arranged on the outer circumferential surface when viewed in the circumferential direction.

As shown in FIG. 8, the ECU 10 includes a circuit board 20, a heat sink 40 that supports the circuit board 20, a bus bar module BBM integrally formed with the connector CNT, and a lid 50. A circuit board 20 and a bus bar module BBM are attached to the heat sink 40. When viewed from the axial direction Ax, the connector CNT is arranged in a direction in which the wire harness can be inserted and removed from the radially outer side of the shaft 31 of the motor 30.

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 board made of resin or the like. 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), and a field effect transistor (FET). Field effect transistors), magnetic sensors, electrolytic capacitors, resistance elements, diodes, thermistors, etc. These plurality of electronic components constitute the detection circuit 23, control circuit 24, first power circuit 25A, and second power circuit 25B shown in FIG.

Heat sink 40 supports circuit board 20 . A circuit board 20 is fixed to one surface (anti-load side) of the heat sink 40. The heat sink 40 is made of a metal with high heat dissipation properties, such as aluminum or copper, and efficiently dissipates the heat generated by the circuit board 20 to the outside.

The lid body 50 is made of metal or resin, and prevents foreign matter and moisture from entering the electric drive device 1.

FIG. 9A is a perspective view showing a configuration example of a busbar module according to an embodiment. FIG. 9B is an explanatory diagram showing an example of the internal configuration of FIG. 9A. FIG. 10A is a perspective view showing a configuration example of a busbar module, viewed from a different direction from FIG. 9A. FIG. 10B is an explanatory diagram showing an example of the internal configuration of FIG. 10A.

As shown in FIGS. 9A, 9B, 10A, and 10B, the bus bar module BBM includes a connector CNT, an electrode terminal portion 64A, an annular portion 63, an electrode terminal portion 64B, a connecting portion 64C, and an arm portion 64D. , a guide portion 64E, a first power terminal Tdc, a second power terminal Tgnd, a communication terminal Tcan for performing CAN communication, and an input/output terminal Tio for inputting and outputting data by a method other than CAN communication. .

As shown in FIG. 9B, the first power supply terminal Tdc is a metal terminal that supplies the power supply voltage Vdc of the power supply device 83 (see FIG. 2). The second power supply terminal Tgnd is a metal terminal that supplies a negative power supply voltage (for example, a reference voltage such as ground) of the power supply device 83. Power wiring PW (see FIG. 2) that transmits power from the power supply device 83 is connected to the first power circuit 25A and the second power circuit 25B via the first power supply terminal Tdc and the second power supply terminal Tgnd, respectively. .

Moreover, as shown in FIG. 9A, the communication terminal Tcan and the input/output terminal Tio are each metal terminals. A signal transmission wiring for transmitting input/output signals such as a steering torque signal T and a vehicle speed signal SV is connected to the control calculation unit 241 (see FIG. 6) of the control circuit 24 via a communication terminal Tcan and an input/output terminal Tio. be done.

The first power terminal Tdc shown in FIG. 9A is inserted into the through hole Hdc shown in FIG. 8. The second power terminal Tgnd shown in FIG. 9A is inserted into the through hole Hgnd shown in FIG. 8 . The first power terminal Tdc2 shown in FIG. 9A is inserted into the through hole Hdc2 shown in FIG. 8. The second power terminal Tgnd2 shown in FIG. 9A is inserted into the through hole Hgnd2 shown in FIG. 8. A communication terminal Tcan shown in FIG. 9A is inserted into the through hole Hcan shown in FIG. 8 . The input/output terminal Tio shown in FIG. 9A is inserted into the through hole Hio shown in FIG. 8.

As shown in FIGS. 9B and 10B, positive busbar wirings 65 and 66, negative busbar wiring 67, and capacitor terminal plate 68 are resin-molded and embedded in the busbar module BBM. The positive bus bar wirings 65 and 66, the negative bus bar wiring 67, and the capacitor terminal plate 68 are formed by punching a metal plate such as copper. The resin of the bus bar module BBM is, for example, polybutylene terephthalate (PBT).

A capacitor 62 is connected between the capacitor terminal plate 68 and the negative bus bar wiring 67. Similarly, a capacitor 62 is connected between the capacitor terminal plate 68 and the positive bus bar wiring 65. A choke coil 61 is connected between the positive bus bar wiring 65 and the positive bus bar wiring 66. The choke coil 61 and the capacitor 62 remove high frequency components of the power wiring PW from the power supply device 83 described above.

As shown in FIG. 9A, the bus bar module BBM includes an electrode terminal portion 64A and an electrode terminal portion 64B. The electrode terminal portion 64A and the electrode terminal portion 64B sandwich the annular portion 63 therebetween. A first power terminal Tdc and a second power terminal Tgnd shown in FIG. 10A are embedded in the electrode terminal portion 64B shown in FIG. 9A. A first power terminal Tdc2 and a second power terminal Tgnd2 shown in FIG. 10A are embedded in the electrode terminal portion 64A shown in FIG. 9A. The first power terminal Tdc and the first power terminal Tdc2 are electrically connected via a positive bus bar wiring 66. The second power terminal Tgnd and the first power terminal Tdc2 are electrically connected via the negative bus bar wiring 67. The first power terminal Tdc and the second power terminal Tgnd are connected to the first power circuit 25A and the second power circuit 25B (see FIG. 6) described above. The first power terminal Tdc2 and the second power terminal Tgnd2 are connected to the control circuit 24 (see FIG. 6). Therefore, the first power supply terminal Tdc has a larger cross-sectional area than the first power supply terminal Tdc2. The second power supply terminal Tgnd has a larger cross-sectional area than the second power supply terminal Tgnd2.

As shown in FIG. 10A, the connecting portion 64C suppresses twisting of the bus bar module BBM and facilitates handling during assembly. An arm portion 64D is provided on the radially outer side of the connecting portion 64C. As shown in FIG. 10A, the guide portion 64E protrudes from the arm portion 64D at least in the axial direction Ax.

As shown in FIG. 8, a through hole 43H for accommodating the guide portion 64E of the bus bar module BBM is provided between the raised portion 46 having the second surface 42 and the outer peripheral edge 43d of the heat sink 40. When the annular portion 63 of the bus bar module BBM is inserted into the groove 43a, the guide portion 64E of the bus bar module BBM is inserted into the through hole 43H.

As shown in FIGS. 8 and 9A, the busbar module BBM has a through hole BBH1 and a through hole BBH2 that penetrate the busbar module BBM. The through hole BBH1 is a long hole, and the through hole BBH2 is a round hole. The through hole BBH1 and the through hole BBH2 may each be a notch. As shown in FIG. 9A, the fixed portion 64W of the busbar module BBM has a through hole 64H that penetrates the busbar module BBM.

Referring to FIG. 8, the substrate main body 21 has a first surface 21b and a second surface 21a located on the opposite side of the first surface 21b. The detection circuit 23, the control circuit 24, the first power circuit 25A, and the second power circuit 25B shown in FIG. 6 are composed of one or more electronic components mounted on the first surface 21b or the second surface 21a. For example, as shown in FIG. 8, the rotation angle sensor 23a is composed of one electronic component mounted on the first surface 21b of the substrate body 21.

Further, the control circuit 24 shown in FIG. 6 is composed of a plurality of electronic components each mounted on the second surface 21a of the board body 21.

Further, the circuit board 20 includes a smoothing capacitor 253 mounted on the second surface 21a of the board body 21.

As shown in FIG. 8, the substrate body 21 is provided with a plurality of through holes 2321 and 2322 that penetrate between the first surface 21b and the second surface 21a.

Further, as shown in FIG. 8, the electric drive device 1 includes a first coil wiring 321 connecting the first coil group Gr1 and the circuit board 20, and a second coil wiring 321 connecting the second coil group Gr2 and the circuit board 20. A coil wiring 322 is provided. The first coil wiring 321 and the second coil wiring 322 may be included in the ECU 10 or the motor 30.

The first coil wiring 321 that has passed through the through hole 43H of the heat sink 40 is inserted into the through hole 2321, and the circuit board 20 and the first coil wiring 321 are electrically connected. The second coil wiring 322 that has passed through the through hole 43H of the heat sink 40 is inserted into the through hole 2322, and the circuit board 20 and the second coil wiring 322 are electrically connected.

As shown in FIG. 9A, inside the annular portion 63, there is a through hole 69 without resin. In this way, the through hole 69 is formed in the main body of the bus bar module BBM. As shown in FIG. 8, the opposite-load side of the shaft 31 of the motor 30 passes through the heat sink 40 and is exposed to the first surface 41.

As shown in FIG. 8, the substrate body 21 is provided with a plurality of through holes BH1 and BH2 that penetrate between the first surface 21b and the second surface 21a. The through hole BH1 and the through hole BH2 may be cutouts. The substrate body 21 is provided with a plurality of through holes Hbt that penetrate between the first surface 21b and the second surface 21a.

The rotation angle sensor 23a is disposed on the anti-load side of the shaft 31 and on an extension line of the axial direction Ax. The substrate body 21 has a plane perpendicular to the axial direction Ax as a mounting surface for the rotation angle sensor 23a. The rotation angle sensor 23a is mounted on the substrate body 21 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 is, for example, a spin valve sensor. A spin valve sensor is an element that detects changes in the direction of magnetic flux using a nonmagnetic layer sandwiched between a pinned layer of ferromagnetic material whose magnetization direction is fixed by an antiferromagnetic layer, etc., and a free layer of ferromagnetic material. It is a sensor that can 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. The sensor chip of the rotation angle sensor 23a will be described later.

As shown in FIG. 8, the heat sink 40 has a step between a first surface 41 and a second surface 42 on the anti-load side of the heat sink main body, and the bus bar module BBM is housed in the step. As a result, in the grooves 43a, 43b, and 43c formed by the step difference between the first surface 41 and the second surface 42, the annular portion 63, the electrode terminal portion 64B, the first power terminal Tdc, and the Two power supply terminals Tgnd are arranged.

As shown in FIG. 8, the heat sink 40 includes a first protrusion 44P, a second protrusion 47, and a third protrusion 48 that protrude from the first surface 41 toward the anti-load side. Note that the first surface 41 does not need to be a flat surface, as long as it is lower than the second surface 42 in the axial direction Ax. Each of the first convex portions 44P has a female screw portion 44H that is opened in the axial direction Ax from the upper surface on the anti-load side. The second convex portions 47 each have a female threaded portion SH that is opened in the axial direction Ax from the upper surface on the anti-load side. Each of the third convex portions 48 has a female screw portion CH that is opened in the axial direction Ax from the upper surface on the anti-load side. As shown in FIG. 8, the lid 50 is fixed to the heat sink 40 by fastening the male threaded portion CT passing through the lid 50 to the female threaded portion CH.

As shown in FIG. 8, the heat sink 40 has a protrusion 46 that protrudes from the first surface 41 toward the anti-load side. The raised portion 46 has a second surface 42 located on the opposite load side than the first convex portion 44P. The second convex portion 47 and the third convex portion 48 protrude more toward the anti-load side than the protruding portion 46 .

As shown in FIG. 8, the heat sink 40 includes a positioning pin 49P1 and a positioning pin 49P2 that protrude from the first surface 41 toward the anti-load side. The positioning pin 49P1 and the positioning pin 49P2 protrude from the raised portion 46 toward the anti-load side.

FIG. 11 is a perspective view illustrating a state in which the busbar module is accommodated in the step of the heat sink. FIG. 12 is a top view illustrating a state in which the busbar module is accommodated in the step of the heat sink. FIG. 13 is a top view illustrating a state in which the busbar module is accommodated in the step of the heat sink and the circuit board is attached. As shown in FIGS. 11 and 12, when the heat sink 40 accommodates the bus bar module BBM, the position of the second surface 42 of the heat sink 40 in the axial direction Ax becomes approximately the same position as the anti-load side surface of the bus bar module BBM. . Thereby, the electric drive device 1 suppresses the size of the motor 30 in the axial direction Ax parallel to the shaft 31 and in the radial direction of the shaft 31.

When the heat sink 40 accommodates the busbar module BBM, the first convex portion 44P shown in FIG. 8 comes into contact with the fixing portion 64W of the busbar module BBM shown in FIG. 9A, and the position of the busbar module BBM in the Z direction is regulated. The through hole 64H shown in FIG. 9A and the female threaded portion 44H shown in FIG. 8 overlap, the male threaded portion BBT is fastened to the female threaded portion 44H, and the bus bar module BBM is fixed to the heat sink 40. As shown in FIG. 11, when the heat sink 40 accommodates the bus bar module BBM, the second convex portion 47 protrudes from the second surface 42 toward the anti-load side.

Further, when the heat sink 40 accommodates the bus bar module BBM, the positioning pin 49P1 shown in FIG. 8 penetrates the through hole BBH1 of the bus bar module BBM. The through hole BBH1 has a portion that is slightly smaller than the diameter of the positioning pin 49P1. Positioning pin 49P2 passes through through hole BBH2 of bus bar module BBM. The through hole BBH2 has a portion that is slightly smaller than the diameter of the positioning pin 49P2.

As shown in FIG. 12, the positioning pin 49P1, the shaft 31 of the motor 30, and the positioning pin 49P2 are aligned on the straight line 49L. The shaft 31 of the motor 30 is located on the straight line 49L. More preferably, the axial direction Ax passing through the center of the shaft 31 of the motor 30 is located on the straight line 49L. Thereby, even if the male threaded portion BBT is fastened to the female threaded portion 44H, the position of the bus bar module BBM relative to the heat sink 40 becomes difficult to move.

The circuit board 20 shown in FIG. 8 comes into contact with the second convex portion 47, and the position of the circuit board 20 in the Z direction is regulated. The female threaded portion SH overlaps the through hole Hbt shown in FIG. The male threaded portion BT is fastened to the female threaded portion SH, and the circuit board 20 is fixed to the heat sink 40. Since the second convex portion 47 protrudes further toward the anti-load side than the second surface 42, a gap is created between the second surface 42 and the circuit board 20.

FIG. 14 is a step view taken along line XIV-XIV in FIG. 13. FIG. 15 is an explanatory diagram for explaining the positional relationship between the shaft and the positioning pin. As shown in FIG. 14, the shaft 31 is rotatably supported by a bearing 33 and a bearing 34. The bearing 33 is interposed between the heat sink 40 and the shaft 31. A bearing support portion 411 is provided on the load side of the heat sink 40, and a hollow portion 35 of the heat sink 40 is provided through which the shaft 31 passes. The bearing 33 is arranged inside the hollow part 35 of the heat sink 40 surrounded by the bearing support part 411. The bearing 34 is interposed between the housing 930 and the shaft 31.

As described above, the magnet 32 is attached to the end of the shaft 31 on the anti-load side. Since the bearing 33 has high component precision, the position of the magnet 32 disposed on the anti-load side of the heat sink 40 in the axial direction Ax is constant.

The positioning pin 49P1 and the positioning pin 49P2 are directly attached to the heat sink 40 and are erected on the first surface 41. Since the length of the positioning pin 49P1 and the positioning pin 49P2 is greater than the thickness of the bus bar module BBM at the position where the through hole BBH1 and the through hole BBH2 are located, as shown in FIG. 11, they protrude beyond the bus bar module BBM.

As shown in FIGS. 13 and 15, the positioning pin 49P1, the shaft 31, and the positioning pin 49P2 are aligned on the straight line 49L in plan view. Thereby, even if the male threaded portion BT is fastened to the female threaded portion SH, the position of the rotation angle sensor 23a relative to the bus bar module BBM becomes difficult to move.

As shown in FIGS. 13 and 15, in this embodiment, the positioning pin 49P1 and the positioning pin 49P2 are positioned to sandwich the shaft 31 in plan view. The through hole BBH1' and positioning pin 49P1' shown in FIG. 15 are a comparative example. The distance from the positioning pin 49P2 to the shaft 31 is L3. In this embodiment, the distance L1 between the positioning pin 49P1 and the positioning pin 49P2 is larger than the distance L3. In the comparative example, the distance L2 between the positioning pin 49P1' and the positioning pin 49P2 is smaller than the distance L3.

Here, in FIG. 15, when the positioning pin 49P1 is at the center of the through hole BBH1 and the positioning pin 49P2 is at the center of the through hole BBH2, the center of the positioning pin 49P1 and the center of the positioning pin 49P2 in plan view. The imaginary line connecting these lines is a straight line 49L.

There is a minute gap (hereinafter referred to as clearance) between the positioning pin 49P1 and the through hole BH1, and there is a minute clearance between the positioning pin 49P2 and the through hole BH2. Although it is desirable to reduce these clearances, there is a limit to how small the clearances can be made.

FIG. 16 is a perspective view for explaining the relationship between the arrangement of heat-generating electronic components on the circuit board and the second surface of the heat sink facing the electronic components. As shown in FIG. 8, the circuit board 20 overlaps the second surface 42 of the heat sink 40 and the bus bar module BBM when viewed in the axial direction Ax. Here, in the circuit board 20, the first power circuit 25A and the second power circuit 25B generate the most heat, so the first power circuit 25A and the second power circuit 25B are arranged so as to face the second surface 42 of the heat sink 40. Placed.

As shown in FIG. 16, the positioning pin 49P1 and the positioning pin 49P2 protrude beyond the circuit board 20 from the load side to the counter-load side. Thereby, the positioning pin 49P1 and the positioning pin 49P2 can be easily guided to the through holes BH1 and BH2 of the circuit board 20.

As shown in FIG. 14, it is desirable that the rotation angle sensor 23a faces the magnet 32, and that the rotation error of the rotation angle sensor 23a with respect to the shaft 31 is small. As explained above, the positioning pin 49P1 and the positioning pin 49P2 are positioned to sandwich the shaft 31 in plan view.

As shown in FIG. 13, there is a clearance between the positioning pin 49P1 and the through hole BBH1, and there is a slight clearance between the positioning pin 49P2 and the through hole BBH2. Due to these clearances, the maximum angle that the virtual line connecting the center of the positioning pin 49P1 and the center of the positioning pin 49P2 makes with the straight line 49L is the angle α. Similarly, the maximum angle between the virtual line connecting the center of the positioning pin 49P1' and the center of the positioning pin 49P2 and the straight line 49L is the angle β. Even if the clearance between the positioning pin 49P1 and the through hole BH1 is the same as the clearance between the positioning pin 49P1' and the through hole BH1', the distance L1 is larger than the distance L3, so the angle α is It becomes smaller than the angle β.

As shown in FIG. 13, since the angle α is smaller than the angle β, the rotation angle sensor 23a can be attached to the heat sink 40 with high accuracy. A shaft 31 is supported by a heat sink 40 via a bearing 33, and a magnet 32 is attached to an end of the shaft 31. As a result, the rotation error of the rotation angle sensor 23a with respect to the shaft 31 becomes small. Then, variations in the detection value of the rotation angle sensor 23a are less likely to occur.

If the clearance is small and the positioning pins 49P1 and 49P2 sandwich the circuit board 20 while stress is applied to the circuit board 20, there is a possibility that the circuit board 20 will be distorted and the rotation angle sensor 23a will be misaligned in the axial direction Ax. There is. On the other hand, in this embodiment, as shown in FIG. 13, the through hole BBH1 of the circuit board 20 is larger in the radial direction RD than in the direction perpendicular to the radial direction. From this, the clearance in the radial direction RD between the positioning pin 49P1 and the through hole BBH1 becomes large, and it is possible for the positioning pin 49P1 and the positioning pin 49P2 to sandwich the circuit board 20 in a state where stress is applied to the circuit board 20. do not have. As a result, the circuit board 20 is not distorted, the rotation angle sensor 23a is less likely to be misaligned in the axial direction Ax, and the detected value of the rotation angle sensor 23a is less likely to vary. Then, the detection accuracy of the rotation angle sensor 23a becomes higher.

The second surface 42 shown in FIG. 8 has a surface 42a sandwiched between the arm portion 64D shown in FIG. 11 and the annular portion 63, and a surface 42b connecting the surfaces 42a.

FIG. 17 is a cross-sectional view for explaining a partial cross-section of the electric drive device. As shown in FIG. 17, a heat dissipating material Tm is applied between the circuit board 20 and the second surface 42 of the heat sink 40 in order to dissipate heat generated by the circuit board 20. The heat dissipating material Tm is, for example, a material in which a silicone polymer is mixed with a thermally conductive filler, and is called TIM (Thermal Interface Material). The heat dissipating material Tm may be any material other than the above-mentioned materials as long as it has a higher thermal conductivity than the board body 21 of the circuit board 20.

In FIG. 16, a field effect transistor TR and a shunt resistor SR, which are electronic components that generate heat, are arranged on the first surface 21b (see FIG. 8) of the circuit board 20. In FIG. 16, the circuit board 20 is drawn with broken lines to indicate the positions of the field effect transistor TR and the shunt resistor SR on the circuit board 20. The field effect transistor TR is provided not only on the switching element 252 shown in FIG. 6 but also on the current cutoff circuit 255, the cutoff drive circuit 243, and the wiring that supplies the power supply voltage Vdc. The shunt resistor SR is provided in the current detection circuit 254 shown in FIG.

A heat dissipating material Tm is provided between the field effect transistor TR and the shunt resistor SR and the heat sink 40. Thereby, the heat of the field effect transistor TR and the shunt resistor SR can be radiated to the heat sink 40. As shown in FIG. 16, the field effect transistor TR and the shunt resistor SR are arranged at positions overlapping the surfaces 42a and 42b shown in FIG. 11 in plan view. Therefore, the heat dissipating material Tm is applied to the entire application area ATm excluding the edges of the surfaces 42a and 42b shown in FIG. As shown in FIGS. 11 and 16, the coating region ATm and the region where the field effect transistor TR and the shunt resistor SR are arranged overlap when viewed in the axial direction Ax.

As shown in FIG. 17, there is a first gap G1 between the outer periphery of the annular portion 63 and the wall surface 46I (see FIG. 17) of the raised portion 46 of the heat sink 40. As shown in FIG. A second gap G2 exists between the arm portion 64D and the wall surface 46O of the raised portion 46. Even if the coefficient of thermal expansion of the busbar module BBM and the coefficient of thermal expansion of the heat sink 40 are different, the first gap G1 and the second gap G2 can alleviate the influence of the thermal expansion of the busbar module. Further, even if the molding tolerance of the busbar module is larger than the shape processing tolerance of the heat sink, the first gap G1 and the second gap G2 exist, so the mounting position of the busbar module BBM with respect to the heat sink 40 is less affected by the molding tolerance. .

The first gap G1 communicates the space between the circuit board 20 and the second surface 42 of the heat sink 40 with the space of the through hole 45H through which the shaft 31 passes through the heat sink 40. Therefore, there is a possibility that the heat dissipating material Tm moves to the vicinity of the shaft 31 of the motor 30 through the first gap G1.

Therefore, in this embodiment, a first protrusion 64P that narrows the first gap G1 is provided on the outer periphery of the annular portion 63 shown in FIGS. 10A and 17. The first protruding portion 64P protrudes from the annular portion 63 toward the raised portion 46. An overlap Δw1 is formed between the end 64PE of the first protrusion 64P and the opposite-load side edge of the wall surface 46I. Thereby, the first protrusion 64P suppresses movement of the heat dissipation material Tm. As a result, the heat dissipating material Tm is easily held between the circuit board 20 and the heat sink 40. Then, heat generation of the circuit board 20 is suppressed, and the heat dissipating material Tm becomes difficult to adhere to the shaft 31. Further, as shown in FIG. 3, even if the axial direction Ax is inclined with respect to the vertical direction VD, the heat dissipating material Tm is easily held between the circuit board 20 and the heat sink 40. Therefore, the degree of freedom of the possible inclination of the axial direction Ax with respect to the vertical direction VD increases. Note that the raised portion 46 is provided with a relief portion 42IE in a portion close to the end portion 64PE of the first protrusion portion 64P. The distance between the raised portion 46 and the end 64PE of the first protrusion 64P can be reduced.

The first protrusion 64P shown in FIGS. 10A and 17 is provided along the edge of the annular portion 63 on the anti-load side. This brings the first protrusion 64P closer to the second surface 42 of the heat sink 40, making it easier to hold the heat dissipation material Tm between the circuit board 20 and the heat sink 40.

As shown in FIG. 17, there is a storage portion 43M in which a portion of the heat sink 40 facing the load side of the annular portion 63 is recessed in the axial direction Ax. Even if the heat dissipation material Tm enters the first gap G1, the heat dissipation material Tm remains in the storage portion 43M, making it difficult for the heat dissipation material Tm to adhere to the shaft 31.

The distance D11 from the circuit board 20 to the magnet 32 is less than half the distance D12 from the circuit board 20 to the first surface 41. Thereby, even if the heat dissipating material Tm reaches the first surface 41, it becomes difficult for the heat dissipating material Tm to adhere to the magnet 32.

The distance D13 from the circuit board 20 to the annular portion 63 of the bus bar module BBM is larger than the distance D11. The distance D14 from the circuit board 20 to the load side surface of the annular portion 63 of the bus bar module BBM is smaller than the distance D12.

The storage portion 43M is formed in an annular shape, and the annular portion 63 of the busbar module BBM covers the storage portion 43M. The distance D15 from the circuit board 20 to the bottom of the storage section 43M is larger than the distance D12.

The second gap G2 communicates the space between the circuit board 20 and the second surface 42 of the heat sink 40 with the space of the through hole 43H. Therefore, there is a possibility that the heat dissipating material Tm moves into the space inside the motor 30 through the second gap G2.

Therefore, the arm portion 64D shown in FIGS. 10A and 17 includes a second protrusion 64PP that narrows the second gap G2. The second protruding portion 64PP protrudes from the arm portion 64D toward the raised portion 46. An overlap Δw2 is formed between the end 64PPE of the second protrusion 64PP and the opposite edge of the wall surface 42I. Thereby, the second protrusion 64PP suppresses movement of the heat dissipation material Tm. As a result, the heat dissipating material Tm is easily held between the circuit board 20 and the heat sink 40. Then, heat generation of the circuit board 20 is suppressed, and the heat dissipating material Tm becomes difficult to adhere to the shaft 31. Further, as shown in FIG. 3, even if the axial direction Ax is inclined with respect to the vertical direction VD, the heat dissipating material Tm is easily held between the circuit board 20 and the heat sink 40. Therefore, the degree of freedom of the possible inclination of the axial direction Ax with respect to the vertical direction VD increases. Note that the raised portion 46 is provided with a relief portion 42IO in a portion close to the end portion 64PPE of the second protrusion portion 64PP. The distance between the raised portion 46 and the end portion 64PPE of the second protrusion portion 64PP can be reduced.

The second protruding portion 64PP shown in FIGS. 10A and 17 is provided along the edge of the arm portion 64D on the anti-load side. This brings the second protrusion 64PP close to the second surface 42 of the heat sink 40, making it easier to hold the heat dissipation material Tm between the circuit board 20 and the heat sink 40.

As shown in FIG. 17, a through hole HB that overlaps the through hole 2321 of the circuit board 20 is formed in the guide portion 64E. The opening center of the through hole HB is parallel to the axial direction Ax. An opening with a diameter DA is provided at the opposite end of the through hole HB. The end of the through hole HB on the load side has an opening with a diameter DB larger than the diameter DA, and a tapered inner wall HBTT gradually decreases from the diameter DB to the diameter DA as it goes inward from the end on the motor stator side. There is. That is, the tapered inner wall HBTT gradually becomes smaller from the diameter DB to the diameter DA as it progresses inward from the load side to the anti-load side in the axial direction Ax.

In advance, the circuit board 20 is fixed to the bus bar module BBM with the guide portion 64E accommodated in the through hole 43H, and the first coil wiring 321 and the second coil wiring 322 shown in FIG. Insert into hole HB. The first coil wiring 321 is guided by the tapered inner wall HBTT (see FIG. 17) and extends along the center of the opening. As a result, the first coil wiring 321 centered at the center of the opening is inserted into the through hole 2321. Similarly, the second coil wiring 322 is guided by the tapered inner wall HBTT (see FIG. 17) in the through hole HB that overlaps the through hole 2322 (see FIG. 8), and comes to align with the center of the opening. As a result, the first coil wiring 321 centered at the center of the opening is inserted into the through hole 2321, and the second coil wiring 322 centered at the center of the opening is inserted into the through hole 2322. The first coil wiring 321 and the second coil wiring 322 are each electrically connected to the internal circuit of the board body 21. This improves the electrical connection stability between the first coil wiring 321 or the second coil wiring 322 and the circuit board 20, and also improves the ease of assembling the electric drive device 1.

FIG. 18 is an explanatory diagram showing the positional relationship between the permanent magnet, the first sensor, and the second sensor of this embodiment. FIG. 19 is a circuit diagram showing the circuit configuration of the sensor chip of this embodiment. As shown in FIG. 17, the rotation angle sensor 23a and the magnet 32 are arranged in the through hole 69 surrounded by the annular portion 63. This prevents foreign matter from entering.

As shown in FIG. 18, the sensor chip of the rotation angle sensor 23a includes a first sensor 116 and a second sensor 124. The rotation angle sensor 23a is a magnetic sensor in which a first sensor 116 and a second sensor 124 are integrated. As shown in FIG. 19, the first sensor 116 includes a first direction detection circuit 118 and a second direction detection circuit 122. The first sensor 116 outputs the detected voltages detected by the first direction detection circuit 118 and the second direction detection circuit 122 to the ECU 10.

The first direction detection circuit 118 includes MR elements R _x1 , R _x2 , R _x3 , and R _x4 , connection terminals T ₁₂ , T ₂₃ , T ₃₄ , and T ₄₁ , and an amplifier 120 . The MR elements R _x1 , R _x2 , R _x3 , and R _x4 are TMR (Tunnel Magneto Resistance) elements. The MR elements R _x1 , R _x2 , R _x3 , and R _x4 may be, for example, any one of a GMR (Giant Magneto Resistance) element, an AMR (Anisotropic Magneto Resistance) element, and a Hall element.

A TMR element is composed of a magnetization fixed layer whose magnetization direction is fixed, a free layer whose magnetization direction changes according to an external magnetic field, and a nonmagnetic layer disposed between the magnetization fixed layer and the free layer. Ru. The resistance value of the TMR element changes depending on the angle that the direction of magnetization of the free layer makes with respect to the direction of magnetization of the fixed magnetization layer. For example, when the angle is 0°, the resistance value is minimum, and when the angle is 180°, the resistance value is maximum. The arrows shown in each MR element R _x1 , R _x2 , R _x3 , and R _x4 shown in FIG. 19 indicate the magnetization direction of the respective magnetization fixed layer. MR elements R _x1 , R _x2 , R _x3 , and R _x4 form a bridge circuit as shown in FIG. 19 .

Connection terminal T ₁₂ and connection terminal T ₃₄ are connected to amplifier 120 . Connection terminal _T41 is connected to drive voltage Vcc. Here, the drive voltage Vcc is shown independently from the ECU 10 for convenience in FIG. 19, but is a voltage supplied from the ECU 10. The connection terminal _T23 is connected to earth GND, as shown in FIG. The ECU 10 applies a voltage between the connection terminal T ₄₁ and the connection terminal T ₂₃ via the harness 18.

Amplifier 120 is an amplification circuit that amplifies input electrical signals. The input side of the amplifier 120 is connected to the connection terminal T ₁₂ and the connection terminal T ₃₄ . The output side of the amplifier 120 is connected to the ECU 10. The amplifier 120 amplifies the detection signals input from the connection terminals T ₁₂ and T ₃₄ and outputs the amplified signals to the ECU 10.

The second direction detection circuit 122 includes MR elements R _y1 , R _y2 , R _y3 , and R _y4 , connection terminals T ₁₂ , T ₂₃ , T ₃₄ , and T ₄₁ , and an amplifier 120 . The second direction detection circuit 122 includes MR elements R _y1 , R _y2 , R _y3 , and R _y4 instead of MR elements R _x1 , R _x2 , R _x3 , and R _x4 . Among the configurations of the second direction detection circuit 122, the same components as those of the first direction detection circuit 118 are given the same reference numerals, and the description thereof will be omitted.

The MR elements R _y1 , R _y2 , R _y3 , and R _y4 have the same configuration as the MR elements R _x1 , R _x2 , R _x3 , and R _x4 except for the magnetization direction of the magnetization fixed layer. The arrows written on each MR element R _y1 , R _y2 , R _y3 , and R _y4 indicate the magnetization direction of the respective magnetization fixed layer.

Note that the second sensor 124 has the same configuration as the first sensor 116, so similar configurations are denoted by the same reference numerals, and a description thereof will be omitted.

When the first direction detection circuit 118 and the second direction detection circuit 122 are arranged at a predetermined distance from the axial direction Ax of the shaft 31 (see FIG. 17), they can output highly accurate detection signals. The first sensor 116 can output a predetermined detection signal when in a predetermined relationship with the magnet 32. In this way, the first sensor 116 needs to be at a predetermined position with respect to the axial direction Ax of the shaft 31 and the magnet 32. Similarly, the second sensor 124 also needs to be at a predetermined position with respect to the axial direction Ax of the shaft 31 and the magnet 32.

As described above, as shown in FIG. 12, the positioning pin 49P1, the shaft 31 of the motor 30, and the positioning pin 49P2 are located on the straight line 49L. As shown in FIG. 13, the positioning pin 49P1, the rotation angle sensor 23a, and the positioning pin 49P2 are aligned on the straight line 49L. Thereby, the first sensor 116 is at a predetermined position with respect to the axial direction Ax of the shaft 31 and the magnet 32. Similarly, the second sensor 124 is also at a predetermined position with respect to the axial direction Ax of the shaft 31 and the magnet 32. As a result, the output accuracy of the rotation angle sensor 23a increases.

As described above, the electric drive device 1 according to the embodiment includes the motor 30, the ECU 10 provided on the opposite load side of the shaft 31 to drive and control the motor 30, and the bus bar module BBM. The ECU 10 includes a magnet 32 at the end of the shaft 31 on the anti-load side, and a circuit board 20 disposed on the anti-load side of the shaft 31 on an extension line of the shaft 31 in the axial direction (for example, the axial direction Ax). ,including. The circuit board 20 includes a detection circuit 23 including a rotation angle sensor 23a that detects rotation of the magnet 32, a control circuit 24, a first power circuit 25A, and a second power circuit 25B. The rotation angle sensor 23a is a magnetic sensor that detects the rotation of the magnet 32.

The busbar module BBM includes a connector CNT, a first power supply terminal Tdc, a second power supply terminal Tgnd, positive busbar wirings 65 and 66 that electrically connect the connector CNT and the first power supply terminal Tdc, and a connector CNT and a second power supply terminal Tgnd. A negative bus bar wiring 67 that electrically connects the two power supply terminals Tgnd is integrally molded with the connector CNT by resin molding.

The positive bus bar wiring 66 and the negative bus bar wiring 67 detour along an extension of the shaft 31 from the connector CNT. The positive bus bar wiring 66 and the negative bus bar wiring 67 are connected to the first power supply terminal Tdc at the through hole Hdc and the through hole Hgnd, which are located at a position where the distance from the connector CNT is greater than the distance from the connector CNT to the extension line of the shaft 31. , are connected to the board body 21 via the second power supply terminal Tgnd. According to this structure, the direction of insertion into and removal from the connector CNT is in the radial direction of the shaft 31 of the motor 30 in a plane perpendicular to the axial direction Ax. Therefore, the size of the electric drive device 1 in the axial direction Ax is suppressed. In addition, since the positive bus bar wiring 66 and the negative bus bar wiring 67 are separate from the power wiring of the board main body 21, the first power circuit 25A and the second power circuit 25B in the board main body 21 are connected to the power supply to the circuit board 20. The area of wiring can be reduced. As a result, the area of the board body 21 is suppressed, and the circuit board 20 becomes smaller. The radial size of the electric drive device 1 is also suppressed.

The rotation angle sensor 23 a is attached to the board body 21 of the circuit board 20 and faces the magnet 32 . A bus bar module BBM is accommodated in the step between the first surface 41 and the second surface 42 of the heat sink 40. The first positioning pin 49P1 and the second positioning pin 49P2 penetrate the bus bar module BBM and the circuit board 20, respectively. The first positioning pin 49P1, the center of the shaft (in the axial direction Ax), and the second positioning pin 49P2 are aligned on the straight line 49L. The relative positions of the circuit board 20, bus bar module BBM, and heat sink 40 are regulated by the first positioning pin 49P1 and the second positioning pin 49P2. Thereby, variations in the relative positions of the circuit board 20, the bus bar module BBM, and the heat sink 40 are reduced. As a result, the accuracy of the relative position between the magnet 32 attached to the shaft 31 and the rotation angle sensor 23a mounted on the circuit board 20 is increased, so the detection accuracy of the rotation angle of the shaft 31 is increased.

That is, the first positioning pin 49P1, the rotation angle sensor 23a, and the second positioning pin 49P2 are aligned on a straight line. This increases the accuracy of the relative position of the rotation angle sensor 23a mounted on the circuit board 20. When the male threaded portion BBT is fastened to the female threaded portion 44H, stress is applied to the busbar module. When the male threaded portion BT is fastened to the female threaded portion SH, stress is applied to the circuit board 20. The first positioning pin 49P1 and the second positioning pin 49P2 are arranged at positions sandwiching the center of the shaft 31. Thereby, the stress of the work of fixing the busbar module BBM to the heat sink 40 is dispersed, and the busbar module becomes difficult to move relative to the heat sink 40. The stress of the work of fixing the circuit board 20 to the heat sink 40 is dispersed, and the bus bar module BBM becomes difficult to move relative to the heat sink 40.

When the groove 43a formed by the step difference between the first surface 41 and the second surface 42 comes into contact with the outer periphery of the annular portion 63 of the busbar module BBM, thereby restricting the mounting position of the busbar module BBM with respect to the heat sink 40. Since the dimensional variations of the bus bar module BBM and the dimensional variations of the heat sink 40 are different, the position of the bus bar module BBM with respect to the heat sink 40 tends to be inaccurate. In this embodiment, the heat sink 40 has a first convex portion 44P and a second convex portion 47 that protrude from the load side to the anti-load side. When the busbar module BBM is accommodated in the step between the first surface 41 and the second surface 42, the busbar module BBM and the first convex portion 44P are brought into contact and fixed. As a result, even if the contact portion between the busbar module BBM and the heat sink 40 is made small and the first gap G1 is provided between the raised portion 46 shown in FIG. 17 and the outer periphery of the annular portion 63 of the busbar module BBM, The position of the busbar module BBM can be regulated. This alleviates the influence of dimensional variations in the bus bar module BBM and the heat sink 40. Further, a second convex portion 47 that protrudes from the load side to the anti-load side with respect to the second surface 42 is in contact with and fixed to the circuit board 20. This creates a gap between the circuit board 20 and the heat sink 40, so that the heat dissipation material Tim is easily held in the gap.

The bus bar module BBM includes a communication terminal Tcan. The communication terminal Tcan is electrically connected to the board body 21 at a position where the distance from the connector CNT is smaller than the distance from the connector CNT to the extension line of the shaft 31. The control circuit 24 can be arranged so that the wiring from the communication terminal Tcan is shortened, and as shown in FIG. 11, the control circuit 24 generates less heat than the first power circuit 25A and the second power circuit 25B. It becomes easier to arrange it near the connector CNT.

At least some of the electronic components (for example, the plurality of switching elements 252) included in the first power circuit 25A and at least some of the electronic components (for example, the plurality of switching elements 252) included in the second power circuit 25B, It is attached to the first surface 21b of the substrate body 21. The second surface 42 of the heat sink 40 and electronic components that generate heat, such as the switching element 252, the field effect transistor TR, and the shunt resistor SR, can face each other directly or via a heat dissipating material. The heat dissipating material is a material made by mixing a silicone polymer with a thermally conductive filler, and is called TIM (Thermal Interface Material). Thereby, the heat generated in the first power circuit 25A and the second power circuit 25B can be dissipated more effectively.

Further, the electric power steering device 100 includes the above-described electric drive device 1, and the electric drive device 1 generates an auxiliary steering torque. Thereby, the size in the axial direction Ax parallel to the shaft 31 of the motor 30 and in the radial direction of the shaft 31 is suppressed, and the degree of freedom in arrangement of the electric power steering device 100 is improved.

1 Electric drive device 10 ECU
18 Harness 20 Circuit board 21 Board body 23a Rotation angle sensor 30 Motor 31 Shaft 32 Magnets 33, 34 Bearing 35 Hollow part 40 Heat sink 41 First surface 42 Second surface 43H Through hole 44P First protrusion 45H Through hole 46 Protrusion 47 Second convex portion 48 Third convex portion 49P1 Positioning pin (first positioning pin)
49P2 Positioning pin (second positioning pin)
50 Lid body 63 Annular part 64D Arm part 64E Guide part 64H Through hole 64W Fixed part 65, 66 Positive bus bar wiring 67 Negative bus bar wiring 69 Through hole 100 Electric power steering device 101 Vehicle 411 Bearing support part 930 Housing 931 Stator core 931a Back yoke 931b Teeth 932 Motor rotor 932a Rotor yoke 932b Magnet 2321 Through hole 2322 Through hole ATm Application area Ax Axial BBM Bus bar module BH1, BH1', BH2, BBH1, BBH1', BBH2 Through hole CNT Connector

Claims (7)

a shaft extending in the axial direction from the load side to the anti-load side;
a motor rotor interlocking with the shaft;
a motor stator that rotates the motor rotor;
a motor including the motor rotor and a cylindrical housing housing the motor stator therein;
a magnet provided at the end of the shaft on the anti-load side;
an electronic control device including a circuit board;
a connector, a first power terminal, a second power terminal, a positive bus bar wiring that electrically connects the connector and the first power terminal, and electrically connects the connector and the second power terminal. a busbar module integrally molded with a negative electrode busbar wiring and having a through hole into which the shaft is inserted;
A heat sink having a hollow portion through which the shaft passes, a first surface provided on the opposite load side, and a first positioning pin and a second positioning pin provided upright on the first surface;
a bearing disposed in the hollow part of the heat sink and supporting the shaft;
Equipped with
The circuit board includes a board main body, and a rotation angle sensor that is arranged on the load side of the board main body and detects rotation of the magnet,
The housing, the heat sink, the bus bar module, and the circuit board are arranged in this order in the axial direction,
The rotation angle sensor faces the magnet,
The first positioning pin and the second positioning pin penetrate the busbar module and the circuit board, respectively,
In the electric drive device, the first positioning pin, the shaft, and the second positioning pin are aligned in a straight line when viewed in the axial direction. The electric drive device according to claim 1, wherein the first positioning pin, the rotation angle sensor, and the second positioning pin are aligned in a straight line when viewed in the axial direction. The electric drive device according to claim 2, wherein the first positioning pin and the second positioning pin are arranged to sandwich the shaft when viewed in the axial direction. The electric drive device according to any one of claims 1 to 3, wherein the first positioning pin and the second positioning pin protrude beyond the circuit board from the load side to the anti-load side. The heat sink has a protrusion having a second surface protruding from the first surface, and a first convex portion and a second convex portion protruding from the first surface toward the anti-load side,
When the busbar module is accommodated in the step between the first surface and the second surface, the busbar module and the first convex portion abut and are fixed,
5 . The circuit board according to claim 1 , wherein the second convex portion that protrudes from the load side toward the anti-load side beyond the second surface is in contact with and fixed to the circuit board. Electric drive. The electric motor according to any one of claims 1 to 5, wherein the through hole of the circuit board through which the first positioning pin penetrates has a radial length larger than a length in a direction orthogonal to the radial direction. Drive device. comprising the electric drive device according to any one of claims 1 to 6,
An electric power steering device in which the electric drive device generates an auxiliary steering torque.

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