Drive unit

Abstract

To provide a driving device that has a configuration in which circuit boards are arranged vertically and that can suppress increase in radial size even when larger-sized components are used.SOLUTION: A driving device 800 comprises a motor 80, a control unit 101, a heat sink 601, and a unit case 20. The heat sink 601 has a pillar part 610 that supports the control unit 101. In the pillar part 610, a pair of first arrangement parts 631 and 632 arranged on both sides of a rotation axis O, and one second arrangement part 641 connecting between the pair of first arrangement parts 631 and 632 are provided while facing radially outward. The unit case 20 is cylindrical and covers the control unit 101. The control unit 101 has circuit boards 301, 302, and 400. When a choke coil 33 and a capacitor 34, which are cylindrical electronic components that configure the control unit 10, are defined as large-sized components, a plurality of large-sized components are arranged in the unit case 20 so that axes of the cylinders are along an axial direction of the rotation axis O.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] In a conventional drive device in which a motor and a control unit are integrally provided, the power module and circuit board of the control unit are arranged along the rotation axis direction. In this type of "vertical arrangement" of the circuit board, it is possible to reduce the radial size.

[0003] For example, in the electric power steering device disclosed in Patent Document 1, the heat sink has a rectangular parallelepiped pillar portion extending in the axial direction of the rotation shaft. Two sets of control boards and power modules that constitute two motor drive circuits are respectively arranged in a pair of arrangement portions corresponding to two opposing sides of the pillar portion and in arrangement portions corresponding to the other two opposing sides. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 073594 Summary of the Invention [Problem to be solved by the invention]

[0005] In this specification, the choke coil and capacitor, which are cylindrical electronic components that make up the control unit, are defined as large components. In the device of Patent Document 1, the cylindrical axis of the capacitor, which is a large component, is arranged so that it is perpendicular to the axial direction of the rotation shaft. Therefore, when using a larger-sized capacitor, there is a problem that it cannot be accommodated in the gap space of the unit case (housing in Patent Document 1).

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a drive device in which the circuit board is arranged vertically and which can suppress radial enlargement even when larger components are used. [Means for solving the problem]

[0007] The drive device according to the present invention includes a motor (80), control units (101, 102), heat sinks (601, 602), and a unit case (20). The motor includes a stator (84) and a rotor (86) that rotates around a shaft (87) provided on a rotation axis (O). The control unit is provided integrally with the motor on one axial side of the rotation axis, and drives and controls the motor.

[0008] The heat sink has pillars (610, 620) that support the control unit. The pillars have a pair of first arrangement parts (631, 632) arranged on either side of the rotation axis, and one or a pair of second arrangement parts (641, 642) that connect the pair of first arrangement parts and face radially outward. A cylindrical unit case covers the control unit supported by the pillars.

[0009] The control unit has one or more circuit boards (301, 302, 400, 401, 402) fixed to the first or second placement portion of the column.

[0010] The choke coil (33) and capacitor (34), which are cylindrical electronic components that make up the control unit, are defined as large components. Multiple large components are arranged inside the unit case with their cylindrical axes aligned with the axial direction of the rotating shaft. For example, at least some of the multiple large components are arranged in series along the axial direction of the rotating shaft. Furthermore, for example, one choke coil and one or more capacitors are arranged in series along the axial direction of the rotating shaft.

[0011] Although there is a limit to the radial direction of the rotating shaft between the circuit board fixed to the pillar portion and the inner wall of the unit case, a space at least equal to the longitudinal dimension of the board is secured in the axial direction of the rotating shaft. In this invention, the cylindrical axes of multiple large components are arranged along the axial direction of the rotating shaft, so even if larger-sized large components are used, they can be efficiently accommodated in the gap space within the unit case. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of an electric power steering device to which a drive device is applied; [Figure 2] Circuit diagram of a dual-motor drive system. [Figure 3] FIG. 2 is an axial cross-sectional view of the drive device according to the first embodiment. [Figure 4] 4 is a view of the column portion of FIG. 3 taken in the direction of arrow IV. [Figure 5] View from the V direction in Figure 3. [Figure 6] FIG. 6 is a radial cross-sectional view taken along line VI-VI in FIG. 3. [Figure 7] FIG. 2 is a side view of the heat sink according to the first embodiment. [Figure 8] FIG. 8 is a view taken in the direction of arrow VIII in FIG. 7. [Figure 9] 9 is a view taken in the direction of an arrow IX in FIG. 7, with a rotation angle sensor substrate added. [Figure 10] FIG. 10 is a diagram showing a modified example of the first embodiment relating to the arrangement of capacitors. [Figure 11] FIG. 6 is an axial cross-sectional view of a drive device according to a second embodiment. [Figure 12] 12 is a radial cross-sectional view taken along line XII-XII in FIG. 11 . [Figure 13] FIG. 10 is an exploded side view of a heat sink according to a second embodiment. [Figure 14] 14 is a view taken in the direction of arrow XIV in FIG. 13. [Figure 15] 14 is a view taken in the direction of the arrow XV in FIG. 13, with a rotation angle sensor board added. [Figure 16] FIG. 4 is a radial cross-sectional view of a drive device according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Several embodiments of the drive device according to the present invention will be described with reference to the drawings. In the several embodiments, substantially identical components are assigned the same reference numerals and will not be described again. The first and second embodiments will be collectively referred to as "the present embodiment." The drive device of the present embodiment is applied, for example, as a steering assist motor for an electric power steering device. This drive device is a so-called "mechanically integrated" drive device in which a motor and a control unit that drives and controls the motor are integrated. Furthermore, in the drive device of the present embodiment, the circuit board of the control unit is arranged along the direction of the rotational axis of the motor. This arrangement of the circuit boards is called a "vertical arrangement."

[0014] [Configuration of electric power steering device] The schematic configuration of an electric power steering device 99 will be described with reference to Fig. 1. Although a rack-assist type electric power steering device is shown in Fig. 1, the drive unit 800 of this embodiment is similarly applicable to a column-assist type electric power steering device. A 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, the electric power steering device 99, etc.

[0015] A torque sensor 93 that detects steering torque is provided on a steering shaft 92 to which a steering wheel 91 is connected. A pinion gear 96 that meshes with a rack shaft 97 is provided at the tip of the steering shaft 92. When the driver turns the steering wheel 91, the rotational motion of the steering shaft 92 is converted into 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 to an angle that corresponds to the amount of displacement of the rack shaft 97.

[0016] The electric power steering device 99 includes a "mechanically and electrically integrated" drive device 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 a rack shaft 97. The motor 80 is a two-system three-phase brushless motor having two sets of three-phase windings, and its output shaft rotates around a rotation axis O.

[0017] The control unit 10 is provided integrally with the motor 80 on one axial side of the rotation axis O, and drives and controls the motor 80. Two inverter systems within the control unit 10 supply three-phase AC power to two sets of three-phase windings, causing the motor 80 to output steering assist torque. DC power is supplied to the power supply connector 23 of the control unit 10 from the on-board batteries BT1 and BT2. A sensor signal detected by an external torque sensor 93 is input to the signal connector 24 via a harness 94.

[0018] 2 shows the circuit configuration of a dual-system motor drive system. The stator of motor 80 has two winding sets 810, 820. Power circuit 310 of the first system converts the power of first battery BT1 and supplies it to first winding set 810 in accordance with commands from control circuit 410. Power circuit 320 of the second system converts the power of second battery BT2 and supplies it to second winding set 820 in accordance with commands from control circuit 420. Because the configurations of power circuits 310, 320 and control circuits 410, 420 of the first and second systems are the same, the same reference numerals will be used without distinction between the components of each system.

[0019] The dual-system system shown in Fig. 2 has a "complete dual-system" configuration in which the power circuits 310, 320 of each system are connected to individual batteries BT1, BT2. Alternatively, the system may have a "dual-drive system" configuration in which the power circuits 310, 320 of each system are connected to a common battery. The power circuits 310, 320 include a choke coil 33, a power supply 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 reference numerals for the batteries BT1, BT2 will be omitted where appropriate.

[0020] The choke coil 33, power relay 35, and reverse polarity protection relay 36 are provided on a power line connecting the positive electrode of the battery and 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. While FIG. 2 shows the capacitor 34 for each system with a single symbol, multiple capacitors 34 may be connected in parallel to ensure sufficient capacity. The choke coil 33 and capacitor 34 form 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 that make up the control unit 10, are defined as "large components."

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

[0022] The inverter 370 includes a plurality of three-phase upper and lower arm switching elements 371-376, each configured with, for example, MOSFETs. More specifically, the upper arm switching elements 371, 372, and 373 of the U-phase, V-phase, and W-phase and the lower arm switching elements 374, 375, and 376 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 of Fig. 2, shunt resistors are provided as current sensors to detect phase currents on the ground side of the switching elements 374, 375, and 376 of the lower arms of each phase. The phase currents detected by the current sensors are input to the microcomputer 43 and used for current feedback control, etc. The arrangement and configuration of the current sensors are not limited to the example of Fig. 2, and any well-known technology may be adopted.

[0024] The motor relays 381, 382, ​​and 383 are configured with, for example, MOSFETs, and are provided in current paths connecting the inter-arm connection points of each phase of the inverter 370 with the winding sets 810 and 820. When the motor relays 381, 382, ​​and 383 are turned OFF, the reverse input from the motor 80 to the inverter 370 is cut off.

[0025] The control circuits 410, 420 include a microcomputer 43 and a driver IC 45, and control the driving of the inverter 370 based on input signals. The microcomputer 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 microcomputer 43 performs control calculations based on the input signals and outputs command signals to the driver IC 45. The driver IC 45 outputs drive signals to the switching elements 371-376 of the inverter 370, the power supply relay 35, the reverse connection protection relay 36, and the motor relays 381, 382, ​​and 383. The microcomputers 43 of the two control circuits 410, 420 may communicate control information, abnormality information, and the like between the systems via inter-microcomputer communication to perform coordinated control.

[0026] [Driver configuration] Next, a specific configuration of the drive device 800 will be described. In this embodiment, the circuit board is "vertically arranged" along the axial direction of the rotation axis O. A conventional drive device with a vertically arranged circuit board is disclosed in Patent Document 1 (International Publication No. 2019 / 073594). Figure 16 shows the configuration of the conventional technology 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 the letters "a" to "f" are added to the end to prevent confusion with the reference numerals of this embodiment.

[0027] In the drive device of the comparative example, control boards 4a and 4b are arranged on a pair of arrangement sections 41d and 41e of column section 41b, and power modules 50a and 50b are arranged on the other pair of arrangement sections 41f and 41g. Power modules 50a and 50b are configured by resin-sealing multiple switching elements that make up an inverter circuit while mounted on wiring. Smoothing capacitors 30a and 30b are fixed to support members 45a and 45b and vertically stacked radially outward from control boards 4a and 4b. This comparative example drive device has the following problems [A]-[C].

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

[0029] [B] In the device of the comparative example, the power modules 50a and 50b are attached in close contact with the heat sink via the signal lines 50c and 50d and the output terminals 51a and 51b. If the close contact with the heat sink is broken due to vibrations caused by an external force, the heat dissipation effect from the power modules 50a and 50b may be reduced.

[0030] [C] In the device of the comparative example, the cylindrical axes of capacitors 30a and 30b, which are large components, are arranged so that they are perpendicular to the axial direction of the rotation shaft. Therefore, when using a larger capacitor, there is a problem that it cannot be accommodated in the gap space of the unit case (housing in Patent Document 1).

[0031] Therefore, this embodiment provides a drive device that solves these problems with a configuration in which the circuit board is arranged vertically. That is, to address problem A, a drive device is provided that has a high heat dissipation effect from the heat-generating elements, to address problem B, a drive device is provided that has a high heat dissipation effect from the switching elements that make up the inverter, and to address problem C, a drive device that can suppress an increase in radial size 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 are written in parentheses.

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

[0033] The lower side of Fig. 3 corresponds to the front side where the output shaft of the motor 80 is provided, and the upper side of Fig. 3 corresponds to the rear side where a connector is provided. In the following description, the terms "upper" and "lower" may be used as appropriate for convenience, based on the viewing direction of Fig. 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 generally cylindrical shape with a bottom, consisting of a bottom portion 831 and a cylindrical portion 832, and a control unit 101 is provided on the opening side. A fastening receiving portion 837 is provided on the outer wall on the opening side of the cylindrical portion 832, and is used to fasten the heat sink 601 to the partition wall portion 70.

[0034] Stator 84 has two three-phase winding groups 810, 820 wound around iron stator core 845 fixed inside cylindrical portion 832 of motor case 83. Stator core 845 is made of laminated steel plates or the like. When electricity is applied from control unit 101 to winding groups 810, 820 via motor wires 85, a rotating magnetic field is formed in stator 84.

[0035] The rotor 86 has a plurality of permanent magnets 866 provided on the outer periphery of an iron rotor core 865. The rotor core 865 is made of laminated steel plates or the like. The rotor 86 rotates about a shaft 87 provided on a rotation axis O due to a rotating magnetic field formed in the stator 84. The shaft 87 fixed to the rotor 86 is rotatably supported by a front bearing 873 held in a bottom portion 831 of the motor case 83 and a rear bearing 874 held in a partition portion 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 surface 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 substantially rectangular parallelepiped pillar portion 610 with the rotation axis O as the axis of symmetry, and a plate-like partition wall portion 70. The pillar portion 610 of the heat sink 601 of the first embodiment has a hollow shape with a recess 649 formed on one surface.

[0037] The heat sink 601 having hollow pillars 610 is suitable for manufacturing the pillars 610 and the partition wall 70 as an integrally molded product by casting or die-casting. By forming the pillars 610 and the partition wall 70 as an integrally molded product, heat transfer is less likely to be blocked, enabling efficient heat dissipation (Problem A). However, the pillars 610 and the partition wall 70 may be manufactured as two parts and then joined by welding or brazing.

[0038] A pair of first arrangement portions 631, 632 and one second arrangement portion 641 that support the control unit 101 are provided on three side surfaces of the pillar portion 610 facing radially outward. The pair of first arrangement portions 631, 632 are arranged parallel to each other with the rotation axis O in between. The one second arrangement portion 641 is perpendicular to the pair of first arrangement portions 631, 632 and connects the pair of first arrangement portions 631, 632. A connector-side end face 65, which is the end face of the pillar portion 610 opposite the motor 80, faces the inner wall of the top panel portion 21 of the unit case 20.

[0039] Support portions 67 to which the power circuit boards 301, 302 are fixed are protruded from the first arrangement portions 631, 632 at multiple locations, i.e., four locations near both ends in the axial and circumferential directions of the rotation axis O. Support portions 67 to which the control circuit board 400 is fixed are protruded from the second arrangement portion 641 at two locations on the center line in the axial direction. The top surface of each support portion 67 forms a flat seat surface 68.

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

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

[0042] A shaft hole 75 into which the rear end of the shaft 87 is inserted is formed in the center of the partition wall 70. 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 pillar 610. The rotation angle sensor 53 detects the rotation angle of the rotor 86 based on changes 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 microcomputer 43 via a rotation angle signal wiring 54. A motor wire hole 76 into which three-phase, two-system motor wires 85 are inserted is formed on the outside of the pillar 610.

[0043] Fastening portions 77 for fastening to the motor case 83 are provided at multiple locations (for example, three locations) on the outer periphery of the main body 71. Screws 17 inserted through threaded holes 78 of the fastening portions 77 are threadedly engaged with fastening receiving portions 837 of the motor case 83, thereby fixing the heat sink 601 and the motor 80 together.

[0044] The outer peripheral side surface 74 of the partition wall portion 70 is exposed to the outside. That is, in the comparative example, the entire heat sink is covered by other components, whereas in this embodiment, the heat sink 601 is fixed to the motor 80 with part of it exposed to the outside. This allows heat from heat-generating elements such as the inverter elements 371-376 to be efficiently released to the outside via the heat sink 601, thereby achieving a high heat dissipation effect (issue A).

[0045] Next, the control unit 101 will be described. In a comprehensive description of all embodiments, the control unit 101 has "one or more circuit boards fixed to the first arrangement portion or the second arrangement 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 "circuit boards" do not include the rotation angle sensor board 501. The three circuit boards in the first embodiment are two power circuit boards 301 and 302 and one control circuit board 400. As for "at least one circuit board," at least the power circuit boards 301 and 302 have heat generating elements mounted thereon.

[0046] Figure 4 shows the mounting layout of power circuit board 301 of the first system. Since the mounting layout of power circuit board 302 of the second system is similar, the first system power circuit board 301 will be used as an example and described with reference to Figure 2. Power circuit board 301 of the first system has mounted thereon a plurality of switching elements 371-376 and the like that constitute inverter 370 in power circuit 310 that supplies power to motor 80. Upper arm elements 371-373 of each phase are connected to power terminal 25p of power system connector 23 via power line 27p. Lower arm elements 374-376 of each phase are connected to ground terminal 25g of power system connector 23 via ground line 27g.

[0047] In addition, a power supply relay 35 and a reverse connection protection relay 36 are mounted on the power supply line 27p, and motor relays 381, 382, ​​and 383 are mounted on the motor 80 side of the inverter 370. As shown by dashed lines (i.e., hidden lines) in Fig. 4, the inverter elements 371-376, which are heat-generating elements, and the relays 35, 36, 381, 382, ​​and 383 are mounted on the surface of the power circuit board 301 facing the heat sink 601. 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, choke coil 33 and capacitor 34, are arranged on the opposite side of power circuit board 301 from heat sink 601. The arrangement of the large components will be described later after referring to unit case 20. In this way, two power circuit boards 301, 302 are provided with two systems of power circuits 310, 320 for supplying power to corresponding winding sets 810, 820 of motor 80. The configuration is simplified by using common circuit boards with the same specifications.

[0049] 3 to 6, two power circuit boards 301 and 302 are fixed to a pair of first arrangement portions 631 and 632. In this embodiment, a power module as in the comparative example is not used, and the power circuit boards 301 and 302, on which the inverter elements 371-376 are directly mounted individually, are fixed to the first arrangement portions 631 and 632 of the heat sink 601. Therefore, it is possible to maintain a high heat dissipation effect from the inverter elements 371-376 regardless of vibrations caused by external forces (objective B). Furthermore, because a power module is not used, it is possible to increase the thickness of the wiring patterns and reduce loss.

[0050] Specifically, the power circuit boards 301, 302 are fastened by the board screws 16 while abutting against bearing surfaces 68 of support portions 67 that protrude from the first arrangement portions 631, 632 at a plurality of locations in the axial direction of the rotation axis O. An anti-loosening adhesive may be applied to the outer peripheries of the board screws 16 or to the screw holes. For example, the support portions 67 are provided at positions corresponding to one end and the other end of the power circuit boards 301, 302 in the axial direction of the rotation axis O, i.e., at two locations in the axial direction. This allows the power circuit boards 301, 302 to be stably fixed to the heat sink 601. Therefore, heat generated by the inverter elements 371-376 mounted on the power circuit boards 301, 302 is efficiently dissipated (Problem B).

[0051] The control circuit board 400 is mounted with components of control circuits 410 and 420 that control the drive of the inverter 370 based on an input signal. In the first embodiment, one control circuit board 400 is provided with two systems of control circuits 410 and 420 that control the drive of the two systems of inverters 370. Therefore, the number of components can be reduced.

[0052] 3, the microcomputer 43, driver IC 45, etc. of the first system control circuit 410 are mounted on the right side of the center line of the control circuit board 400, and the microcomputer 43, driver IC 45, etc. of the second system control circuit 420 are mounted on the left side of the center line. The components of the control circuits 410, 420 of each system are arranged line-symmetrically. This makes the conductor distances equal in each system, resulting in good balance. As with the power circuit boards 301, 302, the components of the control circuits 410, 420 are mounted on the surface 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] An external signal is input to the microcomputer 43 from the control terminal 26 of the control system connector 24 via the external signal wiring 28. Also, a rotation angle signal is input from the rotation angle sensor 53 mounted on the rotation angle sensor board 501 via the rotation angle signal wiring 54. The microcomputer 43 and the driver IC 45 are connected by a communication line 44. The driver IC 45 outputs drive signals via drive signal wiring 46 to the inverter elements 371-376 of the power circuit boards 301 and 302 and to the relays 35, 36, 381, 382, ​​and 383.

[0054] 3 to 6, in the first embodiment, one control circuit board 400 is fixed to one second arrangement portion 641. Similar to the power circuit boards 301 and 302, the control circuit board 400 is fastened by board screws 16 in a state in which the control circuit board 400 abuts against bearing surfaces 68 of support portions 67 that are provided in the second arrangement portion 641 at multiple locations in the axial direction of the rotation axis O.

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

[0056] 3 and 6, a choke coil 33 and a capacitor 34, which are cylindrical electronic components defined as large components, are disposed in the gap between the cylindrical unit case 20 and the power circuit boards 301 and 302. The choke coil 33 and the capacitor 34 are disposed in the unit case 20 with their cylindrical axes aligned in the axial direction of the rotation axis O.

[0057] Furthermore, the choke coils 33 and capacitors 34 of the same system are arranged in series along the axial direction of the rotation axis O. Furthermore, in the modified example shown in FIG. 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 projected range of the large component with the largest diameter. The large components do not need to be arranged strictly on the same axis; they may be eccentric within the projected range. This allows the large components to be arranged more efficiently in the gaps within the unit case 20 compared to the comparative example in which the cylindrical axis of the capacitor is arranged perpendicular to the axial direction of the rotation shaft (Problem C). Therefore, even if a larger-sized large component is used, it can be efficiently accommodated in the gaps within the unit case 20.

[0059] 6, the large components 33 and 34 of the first and second systems are arranged in positions that are point-symmetric with respect to the rotation axis O. This allows the large components 33 and 34 to be efficiently arranged in the gap space where the radial distance from the rotation axis O is maximized (Problem C).

[0060] In addition, the power circuit boards 301, 302 on which the large components 33, 34 are mounted are fixed to support parts 67 provided at multiple locations on the first arrangement parts 631, 632. The large components 33, 34 of each system are arranged on a plane X whose cylindrical axes pass through the middles of the multiple support parts 67 in the circumferential direction of the rotation axis O. This allows the large components 33, 34 to be arranged in a well-balanced manner on the stably fixed power circuit boards 301, 302 (Problem C).

[0061] (Second embodiment) With reference to Figures 11 to 15, the configuration of the drive device of the second embodiment will be described, particularly the differences from the first embodiment. Figures 11 to 12 show the drive device in an assembled state. Figures 13 to 15 show the heat sink 602 alone, and Figure 9 also shows the rotation angle sensor board 502. Here, the heat sink of the second embodiment is designated by the reference numeral "602", and the control unit is designated by the reference numeral "102".

[0062] The drive device 800 mainly includes 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 FIG. 11 is based on FIG. 4 of the first embodiment.

[0063] As shown in FIGS. 13 to 15, the heat sink 602 of the second embodiment has a solid pillar portion 620 without any recesses, and a plate-like partition wall portion 70. For example, the heat sink 602 is formed by joining two parts, the pillar portion 620 and the partition wall portion 70, by welding or brazing. That is, the motor-side end surface 66 of the pillar portion 620 is joined to the upper surface 72 of the partition wall portion 70. In particular, the outer periphery of the motor-side end surface 66 is firmly fixed to the upper surface 72 of the partition wall portion 70. This facilitates manufacturing. However, the pillar portion 620 and the partition wall portion 70 may also be manufactured as an integrally molded product.

[0064] A pair of first arrangement portions 631, 632 and a pair of second arrangement portions 641, 642 that support the control unit 102 are provided facing radially outward on the four side surfaces of the pillar portion 620. The pair of first arrangement portions 631, 632 are the same as those in the first embodiment. The pair of second arrangement portions 641, 642 are perpendicular to the pair of first arrangement portions 631, 632 and connect the pair of first arrangement portions 631, 632. Similar to the first arrangement portions 631, 632, the second arrangement portions 641, 642 have support portions 67 that protrude from them at four locations 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 a rotation angle is attached to the outer periphery of the shaft 87. The sensor magnet 882 and a rotation angle sensor board 502 on which two rotation angle sensors 53 are mounted are arranged on the motor 80 side of the partition wall 70. This makes it possible to accommodate a configuration in which there is no recess in the column portion 620 and the rotation angle sensor board cannot be installed on the control unit 102 side of the partition wall 70. As shown in FIG. 15 , the two rotation angle sensors 53 detect the rotation angle of the rotor 86 based on changes in magnetic flux of the sensor magnet 882. The rotation angle signals detected by the rotation angle sensors 53 are transmitted to the microcomputers 43 of the respective systems via 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 Fig. 12, the two power circuit boards 301 and 302 are fixed to a pair of first arrangement portions 631 and 632, as in the first embodiment. The two control circuit boards 401 and 402 are fixed to a pair of second arrangement portions 641 and 642. The control circuit boards 401 and 402 are fastened by board screws 16 in a state in which the control circuit boards 401 and 402 abut against bearing surfaces 68 of support portions 67 that protrude from each of the second arrangement portions 641 and 642 at multiple locations in the axial direction of the rotation axis O.

[0067] Two control circuit boards 401, 402 are provided with two control circuits 410, 420 for each system, which control the drive of the two inverters 370. As shown in Fig. 11, the control circuit board 401 is mounted with a microcomputer 43 of the first system control circuit 410, a driver IC 45, etc. A rotation angle signal is input to the microcomputer 43 from a rotation angle sensor 53 mounted on a rotation angle sensor board 502 via a rotation angle signal wiring 54. The control circuit board 402 is similarly provided with a second system control circuit 420. The configuration is simplified by using circuit boards with the same specifications in common.

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

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

[0070] However, these features are not necessarily realized as a set, and items (2) and (3) may be combined independently with the three-board configuration of the first embodiment. For example, in the first embodiment, a solid pillar 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, 642. Also, in the first embodiment, the configuration of the sensor magnet and rotation angle sensor board may be replaced with that of the second embodiment.

[0071] (Other embodiments) (a) The cross section of the column portion of the heat sink perpendicular to the rotation axis is not limited to a rectangle, but may be a parallelogram or a trapezoid. The shape of the partition wall and the fastening structure to the motor case are not limited to those of the above embodiment, and any shape or structure may be used as long as it provides the same effects as those of the above embodiment.

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

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

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

[0075] (e) The arrangement of the 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 axial direction of the rotation shaft. Furthermore, 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 being used as a steering assist motor in an electric power steering device, but may also be used as a reaction motor or steering motor in a steer-by-wire system, or as a drive unit for any other motor.

[0077] As described above, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the present invention. [Explanation of symbols]

[0078] 101, 102(10) ···Control unit, 20... unit case, 301, 302: Power circuit board (circuit board), 33···Choke coil (large part), 34 Capacitor (large part), 370···Inverter, 371-376···Switching element (heat generating element), 400, 401, 402: Control circuit board (circuit board), 601, 602...heat sink, 610, 620...Column part, 631, 632...1st placement part, 641, 642...Second placement part, 80···motor, 84···Stator, 86···Rotor, 87···Shaft.

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) that is provided integrally with the motor on one side of the rotation shaft in the axial direction and that drives and controls the motor; a heat sink (601, 602) including a pair of first arrangement portions (631, 632) arranged on either side of the rotation axis, and one or a pair of second arrangement portions (641, 642) connecting the pair of first arrangement portions, which are provided facing radially outward, and having pillar portions (610, 620) that support the control unit; a cylindrical unit case (20) that covers the control unit supported on the pillar portion; A drive device comprising: the control unit has one or more circuit boards (301, 302, 400, 401, 402) fixed to the first arrangement portion or the second arrangement portion of the column; If the choke coil (33) and the capacitor (34), which are cylindrical electronic components that constitute the control unit, are defined as large components, A drive device in which the multiple large parts are arranged within the unit case with their cylindrical axes aligned with the axial direction of the rotation shaft.

2. The drive device according to claim 1 , wherein at least some of the plurality of large components are arranged in series along the axial direction of the rotation shaft.

3. 3. The drive device according to claim 2, wherein one or more of the choke coils and one or more of the capacitors are arranged in series along the axial direction of the rotating shaft.

4. 4. The drive device according to claim 1, wherein the plurality of large components are arranged in point symmetry with respect to the rotation axis.

5. The circuit board on which the large component is mounted is fixed to support portions (67) provided at a plurality of locations in the first arrangement portion, 5. The drive device according to claim 1, wherein the large component has a cylindrical axis arranged on a plane that passes through the middle of the plurality of support portions in the circumferential direction of the rotation shaft.

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