Drive unit

Abstract

To provide a driving device capable of reducing heat applied from a motor driving element to the other circuit.SOLUTION: A driving device integrally comprises a motor and a control unit 40 that controls the motor. The control unit 40 includes: a heat sink and a substrate 41 that are arranged on a rotational shaft O of the motor; a fixing member 51 that fixes the substrate 41; a motor driving element 55 that performs power conduction to the motor; a power wiring pattern 56 that is connected to the motor driving element 55 to supply power; and a control circuit 61 that transmits a control signal to the motor driving element 55. The control circuit 61 is arranged on a substrate center part 45. The power wiring pattern 56 is arranged on a substrate outer peripheral part 46. A screw 51 is made of a material with a heat transmission rate higher than that of the substrate 41, and fixes the substrate 41 to the heat sink as well as being arranged at the substrate outer peripheral part 46. The motor driving element 55 is arranged near the screw 51 between the screw 51 and the control circuit 61.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A known conventional drive device is, for example, that described in Patent Document 1. In Patent Document 1, an electric actuator having a motor and a drive control device serving as a control unit for controlling the motor are integrally provided. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-180155 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the wiring pattern to which the motor drive switching elements are connected is formed up to the fastening holes for fixing the circuit board, and the circuit board is attached to the ECU housing by fastening screws, so that heat transferred from the switching elements to the wiring pattern is released to the ECU housing. However, there is a possibility that heat may be transferred to other circuits mounted on or around the path of the wiring pattern.

[0005] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a drive device that can reduce the heat given off from a motor drive element to other circuits. [Means for solving the problem]

[0006] The drive device of the present invention integrally comprises a motor (20) and a control unit (40) that controls the motor. a heat sink (33) disposed outside the rotation axis (O) of the motor; Located on the motor's rotation axis (O) TajiThe motor drive circuit board includes a plate (41), a fixing member (51) for fixing the board, a motor drive element (55) for supplying current to the motor, a power wiring pattern (56) connected to the motor drive element for supplying power, and a control circuit (61) for sending a control signal to the motor drive element.

[0007] The portion of the substrate within a predetermined distance from the rotation axis and closer to the rotation axis than the outer edge (44) of the substrate is defined as the substrate center (45). The portion of the substrate other than the substrate center is defined as the substrate outer periphery (46).

[0008] The control circuit is disposed in the center of the board. The power wiring pattern includes a power supply pattern connected to the high-potential side of the motor drive element to supply power, and a ground pattern connected to the low-potential side of the motor drive element. A part of the projection area of ​​the ground pattern overlaps with the The fixing member is made of a material with a higher thermal conductivity than the substrate, is placed on the periphery of the substrate, and fixes the substrate to a heat sink. The motor drive element is placed between the fixing member and the control circuit, closer to the fixing member. If the surface of the substrate on which the motor drive element is mounted is referred to as the first mounting surface and the side opposite the first mounting surface is referred to as the second mounting surface, then at the periphery of the substrate, a power supply pattern is provided on the first mounting surface, and a ground pattern is provided on the back side of the power supply pattern on the second mounting surface side. The power supply pattern has an escape recess formed in the area where the fixing member is provided, which opens toward the inside of the board so as not to overlap with the area of ​​the fixing member, and the ground pattern has no escape recess formed therein.

[0009] This structure allows the heat from the motor drive element to be absorbed and dissipated by the heat sink via the fixing member, suppressing the temperature rise of the motor drive element. Because the motor drive element is positioned closer to the fixing member than the control circuit, the heat from the motor drive element is less likely to be transferred to the control circuit. This reduces the impact of heat from the motor drive element on other circuits.

[0010] In conventional motors, wiring patterns are formed up to fastening holes for heat dissipation rather than for power or signal transmission, which increases manufacturing costs. In contrast, in the present invention, heat from the motor drive elements is dissipated to the heat sink via the fixing member, so there is no need to make the wiring patterns larger than necessary for heat dissipation, thereby reducing manufacturing costs. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a longitudinal sectional view of the drive device according to the embodiment. [Figure 2] 2 is a view of the circuit board, electronic components, and screw in FIG. 1 as seen from the direction of arrow II. [Figure 3] Enlarged view of part III in Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the drive device will be described with reference to the drawings.

[0013] [One embodiment] 1, the driving device 10 integrally comprises a motor 20 and a control unit 40 that controls the motor 20. The control unit 40 controls the motor 20 to generate a desired torque based on information input from the outside and information such as the motor current detected inside the control unit 40. The torque of the motor 20 is output to the outside from the output end of the rotating shaft 26.

[0014] Motor 20 is a three-phase brushless motor and includes a stator 21, a rotor 25, and a housing 31 that accommodates them. Stator 21 has a stator core 22 fixed to housing 31 and a three-phase winding set 23 assembled to stator core 22. Three-phase winding set 23 is connected to control unit 40 via lead wires (not shown).

[0015] The rotor 25 has a rotating shaft 26 supported by a rear bearing 35 and a front bearing 36, and a rotor core 27 into which the rotating shaft 26 is fitted. The rotor 25 is provided inside the stator 21 and is rotatable relative to the stator 21. A permanent magnet 37 is provided on one end of the rotating shaft 26.

[0016] The housing 31 has a cylindrical case 32, a front end frame 33 provided at one end of the case 32, and a rear end frame 34 provided at the other end of the case 32. The front end frame 33 and the rear end frame 34 are fastened to each other with bolts (not shown). The front end frame 33 also functions as a heat sink for the control unit 40. Hereinafter, when describing the function of the front end frame 33 as a heat sink, it will be referred to as the "heat sink 33" as appropriate.

[0017] As shown in Figures 1 and 2, the control unit 40 includes a heat sink 33 and a substrate 41 arranged on the rotation axis O of the motor 20, a screw 51 as a fixing member for fixing the substrate 41, a motor drive element 55 for supplying current to the motor 20, a power wiring pattern 56 connected to the motor drive element 55 for supplying power, a control circuit 61 for sending a control signal to the motor drive element 55, and a rotation angle sensor 62 for detecting the rotation angle of the rotating shaft 26.

[0018] The substrate 41 is disposed on the opposite side of the heat sink 33 from the stator 21. In one embodiment, there is one substrate 41, but in other embodiments, there may be two or more substrates. The screws 51 are inserted through the through-holes 42 of the substrate 41. The motor drive element 55 is composed of a switching element such as a MOSFET, and performs switching operation in response to a control signal from the control circuit 61 to switch the energized state of the three-phase winding set 23. The control circuit 61 performs calculations based on information from the outside, a rotation angle sensor 62, etc., and generates signals to command the motor drive element 55, etc.

[0019] The control unit 40 further includes a cover 64 arranged to cover the board 41 and the electronic components mounted thereon, and a connector 66 for connecting the control unit 40 to the outside.

[0020] Cover 64 protects control unit 40 from external impacts and prevents dust, water, and the like from entering control unit 40. Electronic components other than motor drive element 55 and control circuit 61 are not shown in Figures 1 and 2. Connector 66 is fixed to connector connection portion 43 of circuit board 41 with screws 63, and extends outside cover 64 through opening 65.

[0021] A portion of the substrate 41 within a predetermined distance from the rotation axis O and closer to the rotation axis O than an outer edge 44 of the substrate 41 is defined as a substrate central portion 45. Further, a portion of the substrate 41 other than the substrate central portion 45 is defined as a substrate outer peripheral portion 46.

[0022] The control circuit 61 is disposed in the substrate central portion 45. In particular, in one embodiment, the control circuit 61 is disposed on the rotation axis O and approximately in the center of the substrate central portion 45.

[0023] The screws 51 are arranged on the outer periphery 46 of the substrate to ensure a sufficient mounting area, and fix the substrate 41 to the heat sink 33. In one embodiment, three screws 51 are provided at intervals in the circumferential direction around the rotation axis O.

[0024] The power wiring pattern 56 and the motor drive element 55 are arranged on the outer periphery 46 of the substrate. The power wiring pattern 56 is arranged radially outward (i.e., closer to the outer edge 44) than the motor drive element 55, and is formed so as to surround the motor drive element 55 and the control circuit 61 by more than half the circumference and extend along the outer edge 44.

[0025] The mounting surface of the substrate 41 opposite the heat sink 33 is defined as a first mounting surface 47. The mounting surface of the substrate 41 on the heat sink 33 side is defined as a second mounting surface .

[0026] The motor driving element 55 is disposed on the first mounting surface 47. That is, the motor driving element 55 is disposed on the opposite side of the substrate 41 from the heat sink 33.

[0027] The power wiring pattern 56 includes a power supply pattern 57 arranged on the first mounting surface 47 and connected to the high-potential side of the motor driving element 55 to supply power, and a ground pattern 58 arranged on the second mounting surface 48 and connected to the low-potential side of the motor driving element 55.

[0028] The screw 51 is made of a metal material with a higher thermal conductivity than the resin substrate 41, and has a heat receiving portion 52, a threaded portion 53, and a connecting portion 54. The heat receiving portion 52 is made from the head of the screw 51, and is disposed near the motor drive element 55 on the first mounting surface 47. The threaded portion 53 is screwed into the heat sink 33. The connecting portion 54 connects the heat receiving portion 52 and the threaded portion 53.

[0029] The motor driving element 55 is disposed between the screw 51 and the control circuit 61 and closer to the screw 51. In other words, the size of the gap between the motor driving element 55 and the heat receiving part 52 is smaller than the size of the gap between the motor driving element 55 and the control circuit 61.

[0030] (effect) As described above, in one embodiment, the control circuit 61 is arranged in the central portion 45 of the board. The power wiring pattern 56 is arranged in the peripheral portion 46 of the board. The screw 51 is made of a material with a higher thermal conductivity than the board 41, and is arranged in the peripheral portion 46 of the board and fixes the board 41 to the heat sink 33. The motor drive element 55 is arranged between the screw 51 and the control circuit 61, closer to the screw 51.

[0031] With this structure, heat from the motor drive element 55 can be absorbed and dissipated by the heat sink 33 via the screw 51, thereby suppressing a rise in temperature of the motor drive element 55. Because the motor drive element 55 is positioned closer to the screw 51 than the control circuit 61, the heat from the motor drive element 55 is less likely to be transferred to the control circuit 61. This reduces the impact of heat from the motor drive element 55 on other circuits.

[0032] In conventional configurations, wiring patterns are formed up to the fastening holes in the circuit board for heat dissipation rather than for the transmission and reception of power and signals, which increases manufacturing costs. In contrast, in one embodiment, heat from the motor drive element 55 is dissipated to the heat sink 33 via the screws 51, so there is no need to form the power wiring pattern 56 larger than necessary for heat dissipation, thereby reducing manufacturing costs.

[0033] In one embodiment, the power wiring pattern 56 is disposed radially outward compared to the motor drive element 55, and is formed so as to extend along the outer edge 44. By disposing the power wiring pattern 56, through which a larger current flows compared to the signal wiring pattern, as far outward as possible in this manner, heat from the power wiring pattern 56 is more easily released to the outside rather than being trapped inside the drive device.

[0034] In one embodiment, the motor drive element 55 is disposed on the opposite side of the substrate 41 from the heat sink 33. The screw 51 has a heat receiving portion 52 disposed near the motor drive element 55 on the first mounting surface 47 of the substrate 41, a threaded portion 53 that screws into the heat sink 33, and a connecting portion 54 that connects the heat receiving portion 52 and the threaded portion 53. This allows the heat received by the motor drive element 55 at the heat receiving portion 52 located near the motor drive element 55 to be effectively dissipated to the heat sink 33 via the connecting portion 54 and the threaded portion 53.

[0035] [Other embodiments] In other embodiments, the number of screws is not limited to three, but may be two or less, or four or more. Furthermore, other types of fastening members, such as clips or pins, may be used instead of screws. Furthermore, the motor drive element may be disposed across the periphery and center of the substrate.

[0036] 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 invention. [Explanation of symbols]

[0037] 10 drive device, 20 motor, 33 heat sink, 40 control unit, 41 substrate, 44 outer edge, 45 substrate center, 46 substrate outer periphery, 51 screw (fixing member), 55 motor drive element, 56 power wiring pattern, 61 control circuit, O rotation axis.

Claims

1. A drive device integrally comprising a motor (20) and a control unit (40) that controls the motor, The control unit includes a heat sink (33) arranged outside the rotation axis (O) of the motor, a substrate (41) arranged on the rotation axis (O) of the motor, a fixing member (51) for fixing the substrate, a motor drive element (55) for supplying current to the motor, a power wiring pattern (56) connected to the motor drive element for supplying power, and a control circuit (61) for sending a control signal to the motor drive element, A portion of the substrate within a predetermined distance from the rotation axis and closer to the rotation axis than the outer edge (44) of the substrate is defined as a substrate central portion (45), and a portion of the substrate other than the substrate central portion is defined as a substrate outer peripheral portion (46). the control circuit is disposed in the center of the substrate; the power wiring pattern includes a power supply pattern connected to a high potential side of the motor drive element to supply power, and a ground pattern connected to a low potential side of the motor drive element, and is arranged on the outer periphery of the substrate; the fixing member is made of a material having a higher thermal conductivity than the substrate, and is disposed at an outer periphery of the substrate so as to overlap a portion of the projection area of ​​the ground pattern, and fixes the substrate to the heat sink; the motor drive element is disposed between the fixed member and the control circuit and closer to the fixed member, a surface of the substrate on which the motor drive element is mounted is defined as a first mounting surface, and a surface opposite to the first mounting surface is defined as a second mounting surface; the power supply pattern is provided on the first mounting surface at the outer periphery of the substrate, and the ground pattern is provided on the second mounting surface side and on a back side of the power supply pattern; a power supply pattern having an escape recess formed in a location where the fixing member is provided, the escape recess opening toward the inside of the substrate so as not to overlap with the area of ​​the fixing member, and the ground pattern having no escape recess formed therein.

2. The drive device according to claim 1 , wherein the power wiring pattern is disposed radially outward from the motor drive element and is formed to extend along the outer edge.

3. the motor drive element is disposed on the opposite side of the substrate from the heat sink, 3. The drive device of claim 1, wherein the fixing member has a heat receiving portion (52) arranged near the motor drive element on the mounting surface (47) of the board, a threaded portion (53) that screws into the heat sink, and a connecting portion (54) that connects the heat receiving portion and the threaded portion.

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