Drive unit

Abstract

This device provides a drive unit with a vertically arranged circuit board configuration that offers high heat dissipation efficiency from heat-generating elements. [Solution] The drive unit 800 comprises a motor 80, a control unit 102, a heat sink 602, and a sensor unit. The heat sink 602 has a column portion 620 that supports the control unit 102, and a partition wall portion 70 that separates the motor and the control unit in the axial direction of the rotation shaft. The column portion 620 has a pair of first arrangement portions 631, 632 and a pair of second arrangement portions 641, 642 that are arranged facing radially outward. The sensor unit has a sensor magnet 882 attached to the shaft 87, and a rotation angle sensor board 502 on which a rotation angle sensor that detects the rotation angle of the rotor 86 based on the change in magnetic flux of the sensor magnet 882 is mounted. The heat sink 602 is formed by joining the respective components of the column portion 620 and the partition wall portion 70. The sensor unit is positioned on the motor 80 side relative to the partition wall portion 70.

Description

Technical Field

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

Background Art

[0002] Conventionally, in a drive device in which a motor and a control unit are integrally provided, there is known a drive device in which a power module and a circuit board of the control unit are arranged along the rotation axis direction. In such a configuration where the circuit board is "vertically arranged", downsizing in the radial direction is possible.

[0003] For example, in the electric power steering device disclosed in Patent Document 1, the heat sink includes a rectangular parallelepiped column portion extending in the axial direction of the rotation axis. Two sets of control boards and power modules constituting two systems of motor drive circuits are respectively arranged in a pair of arrangement portions corresponding to two opposing surfaces of the column portion and in arrangement portions corresponding to the other two opposing surfaces.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the device of Patent Document 1, the heat sink includes a disk-shaped base portion and a rectangular parallelepiped column portion standing upright at the central portion of the base portion. The base portion is provided inside the inner peripheral wall surface of the cylindrical portion of the motor. Control boards and power modules are arranged in a pair of arrangement portions located on four side surfaces of the column portion and in the other pair of arrangement portions, and the entire column portion is covered with a unit case (housing in Patent Document 1). That is, the heat sink has no portion exposed to the outside. Therefore, the heat dissipation effect from heat generating elements such as switching elements constituting the inverter, which generate heat due to energization of the motor, is insufficient.

[0006] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a drive device in which the circuit board is arranged vertically and which has a high heat dissipation effect from the heat-generating element. [Means for solving the problem]

[0007] The drive device according to the present invention comprises a motor (80), control units (101, 102), heat sinks (601, 602), and a sensor unit. The motor includes a stator (84) and a rotor (86) that rotates about a shaft (87) provided on a rotation axis (O). The control unit is provided integrally with the motor on one side in the axial direction of the rotation axis and drives and controls the motor.

[0008] The heat sink has columnar sections (610, 620) and partition sections (70). The columnar sections have a pair of first arrangement sections (631, 632) positioned on either side of the rotating shaft, and one or a pair of second arrangement sections (641, 642) connecting the pair of first arrangement sections, which face outward and support the control unit. The partition sections are plate-shaped and perpendicular to the rotating shaft, separating the motor and the control unit in the axial direction of the rotating shaft.

[0009] The sensor unit includes a sensor magnet (882) attached to the shaft, and a rotation angle sensor board (502) on which one or more rotation angle sensors (53) that detect the rotation angle of the rotor based on the change in magnetic flux of the sensor magnet are mounted.

[0010] The control unit has multiple heat-generating elements (371-376) that generate heat when the motor is energized, located on at least one of the first or second mounting sections of the column. The heat sink is formed by joining the components of the column and the partition wall. The sensor is located on the motor side relative to the partition wall.

[0011] Thus, in the present invention, the heat of the heating element is efficiently released to the outside through the heat sink, so that a high heat dissipation effect can be obtained. For example, an exposed heat dissipation surface (643) where the heating element of the control unit is not arranged is provided at least on one of the first arrangement part or the second arrangement part of the column part.

Brief Description of the Drawings

[0012] [Figure 1] Schematic configuration diagram of an electric power steering apparatus to which a driving device is applied. [Figure 2] Circuit diagram of a two-system motor drive system. [Figure 3] Axial sectional view of the driving device according to the first embodiment. [Figure 4] View in the direction of arrow IV of the column part in FIG. 3. [Figure 5] View in the direction of arrow V in FIG. 3. [Figure 6] Radial sectional view taken along line VI-VI in FIG. 3. [Figure 7] Side view of the heat sink according to the first embodiment. [Figure 8] View in the direction of arrow VIII in FIG. 7. [Figure 9] View with a rotation angle sensor board added in the direction of arrow IX in FIG. 7. [Figure 10] View showing a modification of the first embodiment regarding the arrangement of capacitors. [Figure 11] Axial sectional view of the driving device according to the second embodiment. [Figure 12] Radial sectional view taken along line XII-XII in FIG. 11. [Figure 13] Exploded side view of the heat sink according to the second embodiment. [Figure 14] View in the direction of arrow XIV in FIG. 13. [Figure 15] View with a rotation angle sensor board added in the direction of arrow XV in FIG. 13. [Figure 16] Radial sectional view of the driving device of the comparative example.

Embodiments for Carrying Out the Invention

[0013] A plurality of embodiments of the drive device according to the present invention will be described based on the drawings. The same reference numerals are assigned to substantially the same configurations in the plurality of embodiments, and the description thereof will be omitted. The "present embodiment" includes the first and second embodiments. The drive device of the present embodiment is applied, for example, as a steering assist motor of an electric power steering device. This drive device is a so-called "mechatronic" drive device in which a motor and a control unit for driving and controlling the motor are integrally configured. Further, in the drive device of the present embodiment, the circuit board of the control unit is arranged along the rotation axis direction of the motor. Such an arrangement of the circuit board is referred to as a "vertical arrangement".

[0014] [Configuration of Electric Power Steering Device] Referring to FIG. 1, the schematic configuration of the electric power steering device 99 will be described. Although FIG. 1 illustrates a rack assist type electric power steering device, the drive device 800 of the present embodiment is similarly applicable to a column assist type electric power steering device. The steering system 90 including the electric power steering device 99 includes a steering wheel 91, a steering shaft 92, a pinion gear 96, a rack shaft 97, wheels 98, and the electric power steering device 99 and the like.

[0015] A torque sensor 93 for detecting a steering torque is provided on the steering shaft 92 to which the steering wheel 91 is connected. A pinion gear 96 that meshes with the rack shaft 97 is provided at the tip of the steering shaft 92. When the driver rotates the steering wheel 91, the rotational motion of the steering shaft 92 is converted into a linear motion of the rack shaft 97 by the pinion gear 96. A pair of wheels 98 connected to both ends of the rack shaft 97 are steered at an angle corresponding to the displacement amount of the rack shaft 97.

[0016] The electric power steering system 99 includes a "mechatronics-integrated" drive unit 800 in which the motor 80 and the control unit 10 are integrated, and a reduction gear 89 that reduces the rotation of the motor 80 and transmits it to the rack shaft 97. The motor 80 is a two-system three-phase brushless motor with two sets of three-phase windings, and its output shaft rotates around the rotation axis O.

[0017] The control unit 10 is integrated with the motor 80 on one axial side of the rotation axis O and drives and controls the motor 80. Three-phase AC power is supplied to two sets of three-phase windings from two inverters within the control unit 10, causing the motor 80 to output steering assist torque. DC power is supplied to the power connector 23 of the control unit 10 from the onboard batteries BT1 and BT2. Sensor signals detected by an external torque sensor 93 are input to the signal connector 24 via the harness 94.

[0018] Figure 2 shows the circuit configuration of a two-system motor drive system. The stator of the motor 80 has two sets of windings 810 and 820. The first power circuit 310 converts the power of the first battery BT1 and supplies power to the first winding 810 according to a command from the control circuit 410. The second power circuit 320 converts the power of the second battery BT2 and supplies power to the second winding 820 according to a command from the control circuit 420. Since the configurations of the first and second power circuits 310 and 320 and the control circuits 410 and 420 are the same, the symbols of the components of each system are not distinguished and are given the same symbols.

[0019] The two-system configuration shown in Figure 2 is a "complete two-system" configuration in which the power circuits 310 and 320 of each system are connected to separate batteries BT1 and BT2. Alternatively, a "two-system drive" configuration may be used in which the power circuits 310 and 320 of each system are connected to a common battery. The power circuits 310 and 320 include a choke coil 33, a power relay 35, a reverse connection protection relay 36, a capacitor 34, an inverter 370, motor relays 381, 382, ​​383, etc. In the following description, the symbols for batteries BT1 and BT2 will be omitted as appropriate.

[0020] The choke coil 33, power relay 35, and reverse connection protection relay 36 are provided on the power line connecting the positive terminal of the battery to the high-potential side of the inverter 370. The capacitor 34 is, for example, an aluminum electrolytic capacitor and is connected in parallel with the inverter 370 on the input side of the inverter 370. In Figure 2, each capacitor 34 is shown with a single symbol, but multiple capacitors 34 may be connected in parallel to ensure sufficient capacitance. The choke coil 33 and capacitor 34 constitute an LC filter and function as noise suppression elements to reduce noise. In this specification, the choke coil 33 and capacitor 34, which are cylindrical components constituting the control unit 10, are defined as "large components".

[0021] The power relay 35 and the reverse connection protection relay 36 are made of, for example, MOSFETs. The parasitic diode of the power relay 35 conducts current from the inverter 370 side to the battery side. When the battery is connected in the forward direction, the power relay 35 cuts off the current from the battery side to the inverter 370 side when it is OFF. The parasitic diode of the reverse connection protection relay 36 conducts current from the battery side to the inverter 370 side. When the battery is connected in reverse, the reverse connection protection relay 36 cuts off the current from the inverter 370 side to the battery side when it is OFF.

[0022] The inverter 370 includes multiple three-phase upper and lower arm switching elements 371-376, each composed of, for example, MOSFETs. Specifically, the switching elements 371, 372, and 373 of the upper arm and the switching elements 374, 375, and 376 of the lower arm are bridge-connected. The switching elements 371-376 of the inverter 370 (hereinafter also referred to as "inverter elements 371-376") are "heat-generating elements" that generate heat when the motor 80 is energized.

[0023] In the configuration example shown in Figure 2, shunt resistors are provided on the ground side of the switching elements 374, 375, and 376 on the lower arm of each phase as current sensors to detect the phase current. The phase current detected by the current sensors is input to the microcontroller 43 and used for current feedback control, etc. The arrangement and configuration of the current sensors are not limited to the example in Figure 2, and any known technology may be used.

[0024] Motor relays 381, 382, ​​and 383 are, for example, composed of MOSFETs and are installed in the current path connecting the inter-arm connection points of each phase of the inverter 370 to the winding assemblies 810 and 820. When motor relays 381, 382, ​​and 383 are turned OFF, the reverse input from the motor 80 to the inverter 370 is interrupted.

[0025] The control circuits 410 and 420 include a microcontroller 43 and a driver IC 45, and control the drive of the inverter 370 based on input signals. The microcontroller 43 receives signals such as the rotation angle of the motor 80 detected by the rotation angle sensor 53 and the steering torque of the driver detected by an external torque sensor 93. The microcontroller 43 performs control calculations based on the input signals and outputs a command signal to the driver IC 45. The driver IC 45 outputs drive signals to the switching elements 371-376, power relay 35, reverse connection protection relay 36, and motor relays 381, 382, ​​and 383 of the inverter 370. The microcontrollers 43 of the two control circuits 410 and 420 may communicate with each other via microcontroller-to-microcontroller communication to exchange control information and abnormal information for each system and perform coordinated control.

[0026] [Drive System Configuration] Next, the specific configuration of the drive unit 800 will be described. In this embodiment, the circuit board is "vertically arranged" along the axial direction of the rotation axis O. Conventionally, a drive unit in which the circuit board is vertically arranged is known, as disclosed in Patent Document 1 (International Publication No. 2019 / 073594). Figure 16 shows the configuration of the prior art based on Figures 2 and 3 of Patent Document 1 as a comparative example. The reference numerals in Patent Document 1 are quoted as they are, but they are followed by the letters "a" to "f", so they will not be confused with the reference numerals in this embodiment.

[0027] In the comparative example drive device, control boards 4a and 4b are arranged in a pair of arrangement sections 41d and 41e of the column section 41b, and power modules 50a and 50b are arranged in another pair of arrangement sections 41f and 41g. The power modules 50a and 50b are constructed by resin-encapsulating multiple switching elements that constitute an inverter circuit, with the elements mounted on the wiring. The smoothing capacitors 30a and 30b are fixed to support members 45a and 45b and are vertically stacked radially outward from the control boards 4a and 4b. The comparative example drive device has the following problems [A]-[C].

[0028] [A] In the comparative example apparatus, the heat sink comprises a disc-shaped base portion and a rectangular column portion 41b that stands upright in the center of the base portion. The base portion is provided on the inside of the inner circumferential wall surface of the cylindrical portion of the motor. Control boards 4a, 4b and power modules 50a, 50b are arranged in a pair of arrangement portions 41d, 41e and another pair of arrangement portions 41f, 41g located on the four sides of the column portion 41b, and the entire column portion 41b is covered by a unit case (housing in Patent Document 1). In other words, the heat sink has no parts that are exposed to the outside. As a result, the heat dissipation effect from heat-generating elements that generate heat when the motor is energized, such as switching elements that constitute the inverter, was insufficient.

[0029] [B] In the comparative example apparatus, power modules 50a and 50b are attached to the heatsink in close contact via signal lines 50c and 50d and output terminals 51a and 51b. If the contact with the heatsink is lost due to vibration caused by external forces, the heat dissipation effect from power modules 50a and 50b may decrease.

[0030] [C] In the comparative example apparatus, the cylindrical axes of the large components, capacitors 30a and 30b, are arranged to be perpendicular to the axis of rotation. Therefore, when using larger capacitors, there was a problem in that they could not be accommodated in the gap space of the unit case (housing in Patent Document 1).

[0031] Therefore, in this embodiment, a drive device is provided that solves these problems with a configuration in which the circuit board is arranged vertically. Specifically, to address problem A, a drive device is provided that has a high heat dissipation effect from the heat-generating element; to address problem B, a drive device is provided that has a high heat dissipation effect from the switching element constituting the inverter; and to address problem C, a drive device is provided that can suppress radial size increase even when using larger components. In the following explanation of the effects of the configuration of this embodiment, the symbols for the corresponding problems A to C will be indicated in parentheses.

[0032] (First Embodiment) Referring to Figures 3 to 9, the configuration of the drive unit of the first embodiment will be described. Figures 3 to 6 show the drive unit in its assembled state. Figures 7 to 9 show the heat sink 601 alone, and Figure 9 includes the rotation angle sensor board 501. Here, the reference numeral "601" is used for the heat sink in the first embodiment, and the reference numeral "101" is used for the control unit. The drive unit 800 mainly comprises a motor 80, a heat sink 601, a control unit 101, and a unit case 20.

[0033] The lower side of Figure 3 corresponds to the front side where the output shaft of the motor 80 is located, and the upper side of Figure 3 corresponds to the rear side where the connector is located. In the following description, the terms "upper" and "lower" may be used as appropriate, based on the viewing direction of Figure 3. The motor 80 includes a stator 84 and a rotor 86 housed in a motor case 83. The motor case 83 is formed in a substantially bottomed cylindrical shape consisting of a bottom portion 831 and a cylindrical portion 832, with a control unit 101 provided on the opening side. A fastening receiving portion 837 used for fastening the heat sink 601 to the partition portion 70 is provided on the outer wall of the opening side of the cylindrical portion 832.

[0034] The stator 84 has two sets of three-phase windings 810 and 820 wound around an iron stator core 845 fixed inside the cylindrical portion 832 of the motor case 83. The stator core 845 is made of laminated steel plates or the like. A rotating magnetic field is formed in the stator 84 when power is supplied from the control unit 101 to the windings 810 and 820 via the motor wire 85.

[0035] The rotor 86 has multiple permanent magnets 866 provided on the outer circumference of an iron rotor core 865. The rotor core 865 is made of laminated steel plate or the like. The rotor 86 rotates around a shaft 87 provided on the rotation axis O due to the rotating magnetic field formed in the stator 84. The shaft 87, which is fixed to the rotor 86, is rotatably supported by a front bearing 873 held at the bottom 831 of the motor case 83 and a rear bearing 874 held at the partition wall 70 of the heat sink 601. In the first embodiment, a sensor magnet 881 for detecting the rotation angle is attached to the rear end face of the shaft 87.

[0036] The heat sink 601 is made of an aluminum alloy or the like. As shown in Figures 7 to 9, the heat sink 601 has a roughly rectangular columnar portion 610 with the rotation axis O as the axis of symmetry, and a plate-shaped partition portion 70. The columnar portion 610 of the heat sink 601 in the first embodiment has a hollow shape with a recess 649 formed on one of its surfaces.

[0037] A heat sink 601 with a hollow column 610 is suitable for manufacturing as a single molded product of the column 610 and the partition wall 70 by casting or die casting. By forming it as a single molded product, heat transfer is less likely to be blocked, and efficient heat dissipation becomes possible (Problem A). However, the column 610 and the partition wall 70 may be manufactured as two separate parts and then joined by welding or brazing.

[0038] On three sides of the column portion 610, a pair of first mounting sections 631 and 632 and a second mounting section 641 are provided, facing radially outward, to support the control unit 101. The pair of first mounting sections 631 and 632 are arranged parallel to each other with the rotation axis O in between. The second mounting section 641 is perpendicular to the pair of first mounting sections 631 and 632 and connects the pair of first mounting sections 631 and 632. The connector-side end face 65 of the column portion 610, which is the end face opposite the motor 80, faces the inner wall of the top plate portion 21 of the unit case 20.

[0039] The first arrangement sections 631 and 632 have support sections 67 protruding at multiple locations, namely four locations near both ends in the axial and circumferential directions of the rotation axis O, to which the power circuit boards 301 and 302 are fixed. The second arrangement section 641 has support sections 67 protruding at two locations at both ends in the axial direction on the circumferential centerline to which the control circuit board 400 is fixed. The top surface of each support section 67 is a flat seating surface 68.

[0040] The side of the second arrangement portion 641 facing the rotation axis O functions as an exposed heat dissipation surface 643. As will be described later, the side of the second arrangement portion 64 facing the rotation axis O corresponds to the side opposite to the side to which the control circuit board 400 is fixed. In the first embodiment, the heat dissipation effect is improved because the heat dissipation surface 643 is secured by forming a recess 649 in the column portion 610 (Problem A).

[0041] The partition wall 70 is plate-shaped and perpendicular to the rotation axis O, separating the motor 80 and the control unit 101 in the axial direction of the rotation axis O. By isolating the motor 80 and the control unit 101 with the partition wall 70, heat from both can be efficiently dissipated (Problem A). The upper surface 72 of the main body 71 of the partition wall 70 is connected to the column 610 side. The lower surface 73 of the main body 71 faces the stator 84 and rotor 86 of the motor 80.

[0042] A shaft hole 75 is formed in the center of the partition wall 70, into which the rear end of the shaft 87 is inserted. A rotation angle sensor board 501, on which a rotation angle sensor 53 is mounted, is installed directly above the shaft hole 75 at the bottom of the recess 649 of the column 610. The rotation angle sensor 53 detects the rotation angle of the rotor 86 based on the change in magnetic flux of a sensor magnet 881 attached to the rear end face of the shaft 87. The rotation angle signal detected by the rotation angle sensor 53 is transmitted to the microcontroller 43 via the rotation angle signal wiring 54. A motor wire hole 76 is formed on the outside of the column 610, through which three-phase two-system motor wires 85 are inserted.

[0043] Multiple fastening portions 77 for fastening to the motor case 83 are provided at several locations (for example, three locations) on the outer circumference of the main body portion 71. The heat sink 601 and the motor 80 are fixed together when a screw 17 inserted through the screw hole 78 of the fastening portion 77 is screwed into the fastening receiving portion 837 of the motor case 83.

[0044] The outer peripheral side surface 74 of the partition wall 70 is exposed to the outside. In other words, in the comparative example, the entire heat sink is covered by other components, whereas in this embodiment, a part of the heat sink 601 is exposed to the outside and fixed to the motor 80. As a result, heat from heat-generating elements such as inverter elements 371-376 is efficiently released to the outside through the heat sink 601, thus achieving a high heat dissipation effect (Problem A).

[0045] Next, the control unit 101 will be described. To describe all embodiments comprehensively, the control unit 10 has "one or more circuit boards fixed to the first or second placement portion of the column portion of the heat sink." In the first embodiment, the control unit 101 has three circuit boards 301, 302, and 400, and in the second embodiment, the control unit 102 has four circuit boards 301, 302, 401, and 402. Note that the rotation angle sensor board 501 is not included in "circuit boards." The three circuit boards in the first embodiment are two power circuit boards 301 and 302 and one control circuit board 400. As "at least one circuit board," at least the power circuit boards 301 and 302 have heating elements mounted on them.

[0046] Figure 4 shows the mounting layout of the first power circuit board 301. The mounting layout of the second power circuit board 302 is similar, so we will use the first power circuit board 301 as an example and explain it with reference to Figure 2. The first power circuit board 301 has multiple switching elements 371-376 etc. mounted on it, which constitute the inverter 370 in the power circuit 310 that supplies power to the motor 80. The upper arm elements 371-373 of each phase are connected to the power terminal 25p of the power connector 23 via the power line 27p. The lower arm elements 374-376 of each phase are connected to the ground terminal 25g of the power connector 23 via the ground line 27g.

[0047] In addition, a power relay 35 and a reverse connection protection relay 36 are mounted on the power line 27p, and motor relays 381, 382, ​​and 383 are mounted on the motor 80 side of the inverter 370. As shown by the dashed lines (i.e., hidden lines) in Figure 4, the heat-generating inverter elements 371-376 and the relays 35, 36, 381, 382, ​​and 383 are mounted on the heat sink 601 side of the power circuit board 301. A heat dissipation gel 18 is filled between the power circuit board 301 and the heat sink 601. This allows for efficient heat dissipation (Problem A).

[0048] The large components, the choke coil 33 and capacitor 34, are positioned on the opposite side of the power circuit board 301 from the heat sink 601. The arrangement of the large components will be described later, after mentioning the unit case 20. Thus, the two power circuit boards 301 and 302 each have two separate power circuits 310 and 320 that supply power to the corresponding winding assemblies 810 and 820 of the motor 80. The configuration is simplified by using circuit boards of the same specifications in common.

[0049] As shown in Figures 3 to 6, the two power circuit boards 301 and 302 are fixed to a pair of first placement sections 631 and 632. In this embodiment, instead of using a power module as in the comparative example, the power circuit boards 301 and 302, on which inverter elements 371-376 are directly mounted individually, are fixed to the first placement sections 631 and 632 of the heat sink 601. Therefore, the heat dissipation effect from the inverter elements 371-376 can be maintained at a high level regardless of vibrations caused by external forces (Problem B). In addition, since a power module is not used, the wiring pattern can be made thicker and losses can be reduced.

[0050] More specifically, the power circuit boards 301 and 302 are fastened to the boards using board screws 16 while in contact with the seating surfaces 68 of support parts 67 that protrude at multiple locations in the axial direction of the rotation axis O in the first placement sections 631 and 632. A thread-locking adhesive may be applied to the outer circumference of the board screws 16 or to the screw holes. For example, the support parts 67 are provided at two locations in the axial direction of the rotation axis O, corresponding to one end and the other end of the power circuit boards 301 and 302. This ensures that the power circuit boards 301 and 302 are stably fixed to the heat sink 601. Therefore, the heat generated by the inverter elements 371-376 mounted on the power circuit boards 301 and 302 is efficiently dissipated (Problem B).

[0051] The control circuit board 400 has components for control circuits 410 and 420 that control the drive of the inverter 370 based on input signals. In the first embodiment, a single control circuit board 400 is provided with both the two control circuits 410 and 420 that control the drive of the two inverters 370. Therefore, the number of components is reduced.

[0052] In Figure 3, the microcontroller 43, driver IC 45, etc. of the first control circuit 410 are mounted on the right side of the center line of the control circuit board 400, and the microcontroller 43, driver IC 45, etc. of the second control circuit 420 are mounted on the left side of the center line. The components of the control circuits 410 and 420 of each system are arranged symmetrically. This ensures that the wire distances are equal for each system, resulting in better balance. Similar to the power circuit boards 301 and 302, the components of the control circuits 410 and 420 are mounted on the side of the control circuit board 400 facing the heat sink 601. In addition, a heat dissipation gel 18 is filled between the control circuit board 400 and the heat sink 601.

[0053] External signals are input to the microcontroller 43 via external signal wiring 28 from the control terminal 26 of the control system connector 24. In addition, a rotation angle signal is input from the rotation angle sensor 53 mounted on the rotation angle sensor board 501 via rotation angle signal wiring 54. The microcontroller 43 and the driver IC 45 are connected by a communication line 44. The driver IC 45 outputs drive signals to the inverter elements 371-376 and relays 35, 36, 381, 382, ​​and 383 of the power circuit boards 301 and 302 via drive signal wiring 46.

[0054] As shown in Figures 3 to 6, in the first embodiment, one control circuit board 400 is fixed to one second mounting section 641. Similar to the power circuit boards 301 and 302, the control circuit board 400 is fastened with board screws 16 while in contact with the seating surfaces 68 of support parts 67 that protrude at multiple locations in the axial direction of the rotation axis O in the second mounting section 641.

[0055] The unit case 20 is made of resin material and has a bottomed cylindrical shape with a top plate portion 21 and an outer cylinder portion 22. The unit case 20 covers the control unit 101 supported by the column portion 610. For example, the lower end of the outer cylinder portion 22 is inserted into and bonded to an annular groove formed in the upper surface 72 of the main body portion 71 of the partition wall portion 70. The top plate portion 21 is provided with a power connector 23 and a signal connector 24. As shown in Figure 5, in a complete two-system configuration, the power connector 23 and signal connector 24 are redundantly provided for each system. In contrast, in a two-system drive configuration where a common battery or external signal is used for both systems, a single pair of connectors 23 and 24 may be provided.

[0056] As shown in Figures 3 and 6, the gap between the cylindrical unit case 20 and the power circuit boards 301 and 302 contains cylindrical electronic components defined as large components: a choke coil 33 and a capacitor 34. The choke coil 33 and the capacitor 34 are positioned within the unit case 20 with their cylindrical axes aligned along the axis of rotation O.

[0057] Furthermore, the choke coil 33 and capacitor 34 of the same system are arranged in series along the axial direction of the rotation axis O. In addition, in the modified example shown in Figure 10, in a configuration in which each system includes multiple capacitors 34, one or more choke coils 33 and multiple capacitors 34 are arranged in series along the axial direction of the rotation axis O. In other words, at least some of the multiple large components are arranged in series along the axial direction of the rotation axis O.

[0058] Here, "arranged in series" means that other large components are included within the projection range of the largest component in diameter. Each large component does not need to be strictly on the same axis and may be eccentric within the projection range. This allows for more efficient placement of large components in the gap space within the unit case 20 compared to the comparative example where the axis of the capacitor cylinder is arranged perpendicular to the axis of rotation (Problem C). Therefore, even if larger large components are used, they can be efficiently accommodated in the gap space within the unit case 20.

[0059] Furthermore, as shown in Figure 6, the large components 33 and 34 of the first and second systems are positioned point-symmetrically with respect to the rotation axis O. This allows the large components 33 and 34 to be efficiently placed in the gap space where the radial distance of the rotation axis O is maximized (Problem C).

[0060] In addition, the power circuit boards 301 and 302, on which the large components 33 and 34 are mounted, are fixed to support parts 67 provided at multiple locations in the first arrangement sections 631 and 632. The large components 33 and 34 of each system are positioned on a plane X whose cylindrical axis passes through the midpoint of the multiple support parts 67 in the circumferential direction of the rotation axis O. As a result, the large components 33 and 34 are balanced and positioned on the stably fixed power circuit boards 301 and 302 (Problem C).

[0061] (Second Embodiment) Referring to Figures 11 to 15, the differences in the configuration of the drive unit of the second embodiment compared to the first embodiment will be explained in particular. Figures 11 to 12 show the drive unit in its assembled state. Figures 13 to 15 show the heat sink 602 by itself, and Figure 9 shows the rotation angle sensor board 502. Here, the reference numeral for the heat sink in the second embodiment is "602", and the reference numeral for the control unit is "102".

[0062] The drive unit 800 mainly comprises a motor 80, a heat sink 602, a control unit 102, and a unit case 20. The motor 80 is the same as in the first embodiment except for the arrangement of the sensor magnet 882. The unit case 20 is the same as in the first embodiment. The right side view of the power circuit board 301 in Figure 11 is the same as in Figure 4 of the first embodiment.

[0063] As shown in Figures 13 to 15, the heat sink 602 of the second embodiment has a solid column portion 620 without recesses and a plate-shaped partition wall portion 70. For example, the heat sink 602 is formed by joining two parts, the column portion 620 and the partition wall portion 70, by welding or brazing. That is, the motor-side end face 66 of the column portion 620 is joined to the upper surface 72 of the partition wall portion 70. In particular, the outer circumference of the motor-side end face 66 is firmly fixed to the upper surface 72 of the partition wall portion 70. This makes manufacturing easier. However, the column portion 620 and the partition wall portion 70 may be manufactured as a single molded product.

[0064] On the four sides of the column portion 620, a pair of first mounting portions 631, 632 and a pair of second mounting portions 641, 642 are provided facing radially outward to support the control unit 102. The pair of first mounting portions 631, 632 are the same as in the first embodiment. The pair of second mounting portions 641, 642 are perpendicular to the pair of first mounting portions 631, 632 and connect the pair of first mounting portions 631, 632. Similar to the first mounting portions 631, 632, the second mounting portions 641, 642 have four support portions 67 protruding from them near both ends in the axial and circumferential directions of the rotation axis O, to which the control circuit boards 401, 402 are fixed.

[0065] In the second embodiment, a sensor magnet 882 for detecting the rotation angle is attached to the outer circumference of the shaft 87. The sensor magnet 882 and the rotation angle sensor board 502 on which the two rotation angle sensors 53 are mounted are positioned on the motor 80 side relative to the partition wall 70. This makes it possible to accommodate configurations where there is no recess in the column 620 and the rotation angle sensor board cannot be installed on the control unit 102 side of the partition wall 70. As shown in Figure 15, the two rotation angle sensors 53 detect the rotation angle of the rotor 86 based on the change in magnetic flux of the sensor magnet 882. The rotation angle signal detected by each rotation angle sensor 53 is transmitted to the respective microcontroller 43 via the rotation angle signal wiring 54.

[0066] As described above, in the second embodiment, the control unit 102 has four circuit boards 301, 302, 401, and 402. As shown in Figure 12, two power circuit boards 301 and 302 are fixed to a pair of first mounting sections 631 and 632, similar to the first embodiment. Two control circuit boards 401 and 402 are fixed to a pair of second mounting sections 641 and 642. The control circuit boards 401 and 402 are fastened with board screws 16 in contact with the seating surfaces 68 of support sections 67 that protrude at multiple locations in the axial direction of the rotation axis O in each of the second mounting sections 641 and 642.

[0067] The two control circuit boards 401 and 402 each contain two separate control circuits 410 and 420 for controlling the drive of two inverters 370. As shown in Figure 11, the control circuit board 401 has the microcontroller 43, driver IC 45, etc., of the first control circuit 410 mounted on it. The microcontroller 43 receives a rotation angle signal from the rotation angle sensor 53 mounted on the rotation angle sensor board 502 via the rotation angle signal wiring 54. The control circuit board 402 is similarly equipped with the second control circuit 420. The configuration is simplified by using circuit boards with the same specifications in common.

[0068] The other configurations of the heat sink 602 and control unit 102 in the second embodiment are the same as in the first embodiment. The effects of the common configurations are as described above.

[0069] As described above, the second embodiment differs from the first embodiment mainly in the following respects. (1) The control unit 102 has a total of four circuit boards, including two control circuit boards 401 and 402. (2) The solid column portion 620 has a pair of second arrangement portions 641 and 642. (3) The sensor magnet 882 and the rotation angle sensor substrate 502 are positioned on the motor 80 side relative to the partition wall 70.

[0070] However, these features do not necessarily have to be realized as a set, and items (2) and (3) may be combined individually with the first embodiment of the three-board configuration. For example, in the first embodiment, a solid column portion 620 may be used, and the control circuit board 400 may be fixed to only one side of the pair of second arrangement portions 641 and 642. Also, in the first embodiment, it is possible to replace the configuration of the sensor magnet and the rotation angle sensor board with that of the second embodiment.

[0071] (Other embodiments) (a) The column portion of the heat sink does not necessarily have to have a rectangular cross-section perpendicular to the axis of rotation; it may also be a parallelogram or a trapezoid. The shape of the partition wall and the fastening structure to the motor case are not limited to the above embodiment, and any shape or structure that can obtain the same effects as the above embodiment is acceptable.

[0072] (b) The drive device of the present invention is not limited to two systems, but may also be applied to a single motor drive system. In that case, one power circuit board may be fixed to only one of the pair of first mounting sections. Alternatively, the electronic components constituting one power circuit may be mounted on two separate power circuit boards and fixed to the pair of first mounting sections. Furthermore, in the case of a two-system configuration, instead of dividing the two power circuits onto two separate power circuit boards for each system, the electronic components for the two systems may be mounted on two separate power circuit boards depending on the type of electronic components, etc.

[0073] (c) In a configuration in which two control circuits are provided on a single control circuit board, the components of each circuit do not need to be arranged symmetrically if an asymmetric arrangement is advantageous for wiring or layout reasons.

[0074] (d) The method of fixing the power circuit board and control circuit board to the column is not limited to fastening with screws, but may also be crimping or pressure welding. As mentioned above, screw fastening and the application of screw-locking adhesive may be used in combination.

[0075] (e) The arrangement of large components is not limited to the above embodiment, and some or all of the large components may be arranged so that the axis of the cylinder is different from the axis of rotation. Also, multiple large components do not have to be arranged in series.

[0076] (f) The drive unit 800 of the present invention is not limited to the steering assist motor of an electric power steering system, but may be used as a drive unit for a reaction motor or steering motor of a steer-by-wire system, or any other motor.

[0077] The present invention is not limited in any way to the embodiments described above, and can be implemented in various forms without departing from its spirit. [Explanation of Symbols]

[0078] 101, 102(10) ... Control unit, 301, 302... Power circuit board (circuit board), 371-376... Switching elements (heating elements), 400, 401, 402... Control circuit boards (circuit boards), 502... Rotation angle sensor board, 53... Rotation angle sensor, 601, 602... Heatsinks, 610, 620...Column part, 631, 632...first placement part, 641, 642...Second placement part, 70...Bulkhead part, 80...motor, 84... Stator, 86... Rotor, 87... Shaft, 882... Sensor magnet.

Claims

1. A motor (80) including a stator (84) and a rotor (86) that rotates around a shaft (87) provided on a rotation axis (O), A control unit (101, 102) is provided integrally with the motor on one side of the axial direction of the rotating shaft and drives and controls the motor, A pair of first arrangement parts (631, 632) are arranged on either side of the rotating shaft, one or a pair of second arrangement parts (641, 642) connecting the pair of first arrangement parts are provided facing radially outward, and a column part (610, 620) supports the control unit, and a heat sink (601, 602) is plate-shaped perpendicular to the rotating shaft and has a partition wall part (70) that separates the motor and the control unit in the axial direction of the rotating shaft, A sensor unit having a sensor magnet (882) attached to the shaft, and a rotation angle sensor board (502) on which one or more rotation angle sensors (53) that detect the rotation angle of the rotor based on the change in magnetic flux of the sensor magnet are mounted, A drive device equipped with, The control unit has a plurality of heating elements (371-376) that generate heat when the motor is energized, and these are arranged in at least one of the first arrangement portion or the second arrangement portion side of the column. The heat sink is formed by joining together the column portion and the partition wall portion. The sensor unit is a drive device located on the motor side with respect to the partition wall.

2. The drive device according to claim 1, wherein at least one of the first arrangement portion or the second arrangement portion of the column portion is provided with an exposed heat dissipation surface (643) on which the heat-generating element of the control unit is not arranged.

3. The drive device according to claim 1, wherein the circuit boards (301, 302) on which the heating element of the control unit is mounted are fastened to the heat sink by a plurality of screws (16).

4. The drive device according to claim 1, wherein the heating element is mounted on the surface of a circuit board in which a heat dissipation gel (18) is filled between it and the heat sink.

5. The circuit board is fastened to the heat sink by a plurality of screws (16). The drive device according to claim 4, wherein the heat dissipation gel is filled in the area surrounded by the plurality of screws.

6. The drive device according to any one of claims 1 to 5, wherein the outer peripheral surface (74) of the partition wall is exposed to the outside.

7. The drive device according to claim 1, wherein the motor wire hole (76) through which the motor wire (85) that energizes the stator is inserted is located outside the column portion and is positioned on either side of the column portion.

8. The control unit is The power circuit that supplies power to the motor includes one or two power circuit boards (301, 302) on which a plurality of switching elements (371-376) constituting an inverter (370) are mounted, and one or two control circuit boards (400, 401, 402) on which components of a control circuit that controls the drive of the inverter based on an input signal are mounted. The power circuit board is fixed to the first arrangement section, The drive device according to claim 1, wherein the control circuit board is fixed to the second arrangement portion.

9. The stator of the motor has two sets of windings (810, 820), The drive device according to claim 8, wherein the control unit has two power circuit boards, each provided with two separate power circuits (310, 320) for supplying power to the corresponding winding assemblies of the motor.

10. The drive device according to claim 9, wherein the control unit has two control circuit boards (401, 402) each provided with two control circuits (410, 420) for controlling the drive of the two inverters.

11. The drive device according to claim 9, wherein the control unit has a single control circuit board (400) on which two control circuits (410, 420) for controlling the drive of the two inverters are both provided.

12. The drive device according to claim 11, wherein the control circuit board has components of each control circuit arranged symmetrically.

13. The drive device according to any one of claims 8 to 12, wherein at least the power circuit board is fixed in the first arrangement portion in contact with the seating surfaces (68) of support portions (67) protruding from multiple locations in the axial direction of the rotating shaft.

14. The drive device according to claim 13, wherein at least the plurality of support portions in the first arrangement portion are provided at positions corresponding to one end and the other end of the power circuit board in the axial direction of the rotation shaft.

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