Motor device
The motor device addresses heat transfer issues by using a heat sink extension to redirect heat away from the sealing material, maintaining sealing integrity and reducing adhesive deterioration, thus enhancing reliability and efficiency.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- JTEKT CORP
- Filing Date
- 2025-01-17
- Publication Date
- 2026-07-23
Smart Images
Figure JP2025001324_23072026_PF_FP_ABST
Abstract
Description
Motor device
[0001] The present disclosure relates to a motor device.
[0002] For example, the motor device of Patent Document 1 has a motor and an ECU that controls the driving of the motor. The ECU is attached to the axial end of the motor via a metal frame member. The ECU has a substrate on which various electronic components including a heating element are provided. The heating element is disposed on the surface of the substrate facing the frame member. The heat generated by the heating element is radiated to the frame member via a heat dissipation material.
[0003] The motor device of Patent Document 1 has a cover member. The cover member is attached to the frame member so as to cover the ECU. The tip of the peripheral wall of the frame member is fixed to the frame member with an adhesive in a state of being inserted into an adhesive groove provided on the surface of the frame member opposite to the motor. Thereby, it is possible to prevent water or the like from entering the inside of the cover member from the gap between the frame member and the cover member.
[0004] Japanese Unexamined Patent Application Publication No. 2019 - 216604
[0005] The motor device of Patent Document 1 has the following concern. That is, there is a possibility that the heat from the heating element is transmitted to the adhesive via the frame member. This promotes the deterioration of the adhesive. When the adhesive deteriorates, there is a concern that the sealing performance between the inside and the outside of the cover member may decrease.
[0006] A motor device according to one aspect of the present disclosure includes a motor having a first end on which an output shaft protrudes and a second end on the opposite side of the first end, on which a metal heat sink is provided; a connector assembly disposed to the side of the motor when viewed in the axial direction of the motor; and a substrate disposed to overlap the heat sink and the connector assembly when viewed in the axial direction of the motor. The second end has a metal housing portion that accommodates the portion of the heat sink exposed from the second end, and the housing portion has a protruding portion that extends to the side of the motor. A fitting hole is provided in the end wall of the protruding portion that penetrates in the axial direction of the motor, and the connector assembly is configured to be fitted into the fitting hole via a sealing material. The heat sink has an extension portion that extends inside the housing portion toward the fitting hole. An electronic component configured to generate heat when energized is provided in the region of the substrate that overlaps with the extension portion when viewed in the axial direction of the motor. The electronic component is configured to contact the extension portion in a heat-transferable manner.
[0007] Figure 1 is a perspective view showing the external appearance of a motor device according to one embodiment. Figure 2 is a perspective view of the motor device of Figure 1 in an exploded view. Figure 3 is a cross-sectional view of the main part of the motor device of Figure 1. Figure 4 is a cross-sectional view of the heat dissipation area of the extension of Figure 3. Figure 5 is a cross-sectional view of the main part of a motor device according to a comparative example. Figure 6 is a cross-sectional view of the main part of a motor device according to a comparative example.
[0008] A motor device 11 according to one embodiment will be described. The motor device 11 is mounted, for example, on the steering system of a vehicle. The steering system includes an electric power steering system and a steer-by-wire steering system.
[0009] <Overall Configuration> As shown in Figure 1, the motor device 11 includes a motor 12 and an electronic control device 13. The motor 12 is, for example, a three-phase brushless motor. The three phases are U-phase, V-phase, and W-phase. The motor 12 has two sets of windings. The electronic control device 13 is provided at the axial end of the motor 12. The electronic control device 13 independently controls the power supply to the two sets of windings.
[0010] <Motor 12> As shown in Figure 2, the motor 12 has a case 12A. The case 12A is a cylindrical metal body with a circular cross-section. Inside the case 12A are a stator, a busbar module, and a rotor. The stator has a core and a plurality of windings. The core is a hollow cylindrical body with a circular cross-section and is fitted to the inner surface of the case 12A. The plurality of windings are wound around the core via an insulator. The busbar module has a holder made of synthetic resin and a plurality of busbars held in the holder. The busbars correspond to each of the three phases. One end of a winding is connected to each busbar. The rotor is inserted into the stator and the busbar module without contact. The rotor has an output shaft 12B and a magnet fixed to the outer surface of the output shaft 12B. The magnet is a cylindrical body with a circular cross-section. The output shaft 12B is rotatably supported by bearings on the inner circumferential surface of the case 12A.
[0011] The motor 12 has a first end on the side from which the output shaft 12B protrudes, and a second end on the opposite side from the first end. The first end of the motor 12 is also the first end of the case 12A, and the second end of the motor 12 is also the second end of the case 12A.
[0012] A housing portion 21 is provided at the second end of the motor 12. The housing portion 21 is made of metal and is integrally provided with the case 12A. The housing portion 21 is a box-shaped body with a rectangular cross-section and has an opening 21A. The opening 21A opens in the direction opposite to the direction in which the output shaft 12B of the motor 12 protrudes. The housing portion 21 has a protruding portion 21B. The protruding portion 21B is the part of the housing portion 21 that protrudes to the side of the motor 12. The side is perpendicular to the axial direction of the motor 12. The housing portion 21 has a fitting hole 21C. The fitting hole 21C is provided in the end wall of the protruding portion 21B. The end wall of the protruding portion 21B is also the end wall of the housing portion 21. The fitting hole 21C penetrates the end wall of the protruding portion 21B in the axial direction of the motor 12. The shape of the fitting hole 21C is, for example, a rectangle extending tangentially to the case 12A when viewed from the axial direction of the motor 12. The four corners of the rectangle may be rounded.
[0013] A heat sink 22 is provided at the second end of the motor 12. The heat sink 22 is made of a metal with excellent thermal conductivity, such as aluminum. The second end of the case 12A is open, and a part of the heat sink 22 is fitted into the second end of the case 12A. The heat sink 22 also functions as a bearing holder. The bearing holder is a member that holds a bearing that rotatably supports the output shaft 12B. The heat sink 22 has a heat sink body 22A and an extension portion 22B.
[0014] The heat sink body 22A is a cylindrical body having a circular cross-sectional shape. The heat sink body 22 has a first end that fits into the second end of the case 12A, and a second end that penetrates the end wall of the housing 21 in the axial direction of the motor 12 and is exposed inside the housing 21.
[0015] The extension portion 22B is provided at the second end of the heat sink body 22A. The extension portion 22B is a plate-like body that extends from the outer circumferential surface of the heat sink body 22A toward the fitting hole 21C when viewed from the axial direction of the motor 12, and is arranged inside the housing portion 21. The extension portion 22B extends to the vicinity of the fitting hole 21C. The extension portion 22B widens toward the fitting hole 21C when viewed from the axial direction of the motor 12. The surface of the extension portion 22B opposite to the heat sink body 22A extends linearly along the long side of the fitting hole 21C, and has, for example, approximately the same length as the length of the long side of the fitting hole 21C. The outer circumferential surface of the heat sink body 22A and the outer circumferential surface of the extension portion 22B are continuous via a smooth curved surface. The extension portion 22B has a first end face that faces the end wall of the overhang portion 21B in the axial direction of the motor 12, and a second end face that is flush with the second end face of the heat sink body 22A. The second end face of the heat sink body 22A is the end face opposite to the first end of the heat sink body 22A that is fitted into the second end of the case 12A.
[0016] The heat sink 22 is provided with three first motor terminals 23A. The three first motor terminals 23A correspond to the three phase windings that constitute the first winding group. Each of the first motor terminals 23A is part of a busbar. Inside the case 12A, one end of the first winding of each phase is connected to the busbar of the corresponding phase. The first motor terminals 23A penetrate the heat sink 22 in the axial direction of the motor 12 via an insulating member. The three first motor terminals 23A are arranged in a line tangentially to the contour of the motor 12 when viewed from the axial direction of the motor 12.
[0017] The heat sink 22 is provided with three second motor terminals 23B. The three second motor terminals 24A correspond to the three phase windings that constitute the second winding group. Each of the second motor terminals 23B is part of a busbar. Inside the case 12A, one end of the second winding of each phase is connected to the busbar of the corresponding phase. The second motor terminals 23B penetrate the heat sink 22 in the axial direction of the motor 12 via an insulating member. The three second motor terminals 23B are arranged in a line tangentially to the contour of the motor 12 when viewed from the axial direction of the motor 12.
[0018] The ends of the heat sink 22, from which the first motor terminal 23A and the second motor terminal 23B protrude, are exposed inside the housing 21. <Electronic control unit 13> As shown in Figure 2, the electronic control unit 13 includes a connector assembly 31, a circuit board 32, and a cover 33.
[0019] The connector assembly 31 has a body 41 made of synthetic resin. The body 41 includes a base 41A, a first power connector 41B, a second power connector 41C, a first signal connector 41D, and a second signal connector 41E.
[0020] The base 41A is, for example, a box-shaped body having a rectangular cross-section, and opening in the same direction as the opening 21A of the housing section 21. The rectangle includes a rectangle or a trapezoid. The base 41A has a first end face facing in the opposite direction to the opening 21A of the housing section 21, and a second end face facing in the opposite direction to the first end face, i.e., in the same direction as the opening 21A of the housing section 21. The direction opposite to the opening 21A of the housing section 21 is downward in Figure 2. The direction in the same direction as the opening 21A of the housing section 21 is upward in Figure 2. The first end face of the base 41A is also the first end face of the body 41, and the second end face of the base 41A is also the second end face of the body 41.
[0021] The first power connector 41B is provided on the first end face of the base 41A. The first power connector 41B is a cylindrical body that extends from the first end face of the base 41A in the axial direction of the motor 12. The first power connector 41B is open in the direction that the first end face of the base 41A faces. The first power connector 41B is a so-called male connector.
[0022] The first power connector 41B is mated with the first mating connector, which is a so-called female connector. The first power connector 41B is mated inside the first mating connector. The first mating connector is connected via first wiring to a DC power source such as a battery located outside the motor device 11. The first power connector 41B is a first power connector for supplying power from the DC power source to the circuit board 32.
[0023] The second power connector 41C is provided on the first end face of the base 41A. The second power connector 41C is a so-called male connector having the same configuration as the first power connector 41B. The first power connector 41B and the second power connector 41C are spaced apart in the direction of the long side of the base 41A. The direction of the long side is the direction in which the length of the side of the base 41A is longer.
[0024] The second power connector 41C is mated with a second mating connector, which is a so-called female connector. The second power connector 41C is mated inside the second mating connector. The second mating connector is connected via second wiring to a DC power source, such as a battery, located outside the motor device 11. The second power connector 41C is a second power connector for supplying power from the DC power source to the circuit board 32.
[0025] The first signal connector 41D is provided on the first end face of the base 41A. The first signal connector 41D is positioned between the first power connector 41B and the second power connector 41C in the long-side direction of the base 41A. The first signal connector 41D is a cylindrical body that extends from the first end face of the base 41A in the axial direction of the motor 12. The first signal connector 41D opens in the direction that the first end face of the base 41A faces. The third connector 41C is a so-called male connector.
[0026] The first signal connector 41D is mated with a third mating connector, which is a so-called female connector. The first signal connector 41D is mated inside the third mating connector. The third mating connector is connected via a third wiring to a vehicle control device located outside the motor device 11. The first signal connector 41D is a first signal connector for sending and receiving signals between the circuit board 32 and the vehicle control device.
[0027] The second signal connector 41E is provided on the first end face of the base 41A. The second signal connector 41E is a so-called male connector having the same configuration as the first signal connector 41D. The second signal connector 41E is positioned between the second power connector 41C and the first signal connector 41D in the long side direction of the base 41A.
[0028] The second signal connector 41E is mated with its mating partner, the fourth mating connector. The fourth mating connector is a so-called female connector. The second signal connector 41E is mated inside the fourth mating connector. The fourth mating connector is connected via a fourth wiring to a vehicle control device located outside the motor device 11. The second signal connector 41E is a second signal connector for sending and receiving signals between the circuit board 32 and the vehicle control device.
[0029] The connector assembly 31 has a first power terminal 42 and a first ground terminal 43. The first power terminal 42 is provided along a path that extends from inside the first power connector 41B and penetrates the base 41A in the axial direction of the motor 12. The first end of the first power terminal 42 is located inside the first power connector 41B. The second end of the first power terminal 42 is upright with respect to the second end face of the base 41A. The first ground terminal 43 is provided in the same manner as the first power terminal 42. The first power terminal 42 and the first ground terminal 42 are spaced apart in the long side direction of the base 41A.
[0030] The connector assembly 31 has a second power terminal 44 and a second ground terminal 45. The second power terminal 44 is provided along a path that extends from inside the second power connector 41C and penetrates the base 41A in the axial direction of the motor 12. The first end of the second power terminal 44 is located inside the second power connector 41C. The second end of the second power terminal 44 is upright with respect to the second end face of the base 41A. The second ground terminal 45 is provided in the same manner as the second power terminal 44. The second power terminal 44 and the second ground terminal 45 are spaced apart in the long side direction of the base 41A.
[0031] The connector assembly 31 has a plurality of first signal terminals 46. The first signal terminals 46 are provided along a path that extends from inside the first signal connector 41D and penetrates the base 41A in the axial direction of the motor 12. The first end of the first signal terminal 46 is located inside the first signal connector 41D. The second end of the first signal terminal 46 is upright relative to the second end face of the base 41A. The plurality of first signal terminals 46 are arranged at intervals along the long side of the base 41A.
[0032] The connector assembly 31 has a plurality of second signal terminals 47. The second signal terminals 47 are provided along a path that extends from inside the second signal connector 41E and penetrates the base 41A in the axial direction of the motor 12. The first end of the second signal terminal 47 is located inside the second signal connector 41E. The second end of the second signal terminal 47 is upright with respect to the second end face of the base 41A. The plurality of second signal terminals 47 are arranged at intervals along the long side of the base 41A.
[0033] The connector assembly 31 is attached to the housing 21 of the motor 12. The first power connector 41B, the second power connector 41C, the first signal connector 41D, and the second signal connector 41E are inserted into the fitting holes 21C through the opening 21A of the housing 21. The outer circumferential surface of the base 41A is fitted to the inner circumferential surface of the fitting holes 21C of the housing 21. A flange portion 41F is provided around the entire circumference of the outer circumferential surface of the base 41A. The flange portion 41F is maintained in contact with the peripheral portion of the fitting holes 21C of the end wall of the protruding portion 21B in the axial direction of the motor 12. The first power connector 41B, the second power connector 41C, the first signal connector 41D, and the second signal connector 41E protrude from the end wall of the protruding portion 21B in the direction opposite to the opening 21A of the housing 21.
[0034] The circuit board 32 is positioned corresponding to the housing section 21. The outer contour shape of the circuit board 32 corresponds to the inner contour shape of the housing section 21 when viewed from the axial direction of the motor 12. The circuit board 32 is positioned overlapping the end of the heat sink 22 exposed inside the housing section 21 and the end of the connector assembly 31 exposed inside the housing section 21. The circuit board 32 is fixed to a support provided on the body 41 and a support provided inside the housing section 21, for example, by screws. The screws pass through the circuit board 32 and are tightened into the support. The circuit board 32 is maintained in a position perpendicular to the axial direction of the motor 12.
[0035] The second end of the first power terminal 42 is inserted into the corresponding first power terminal hole of the substrate 32. The second end of the first ground terminal 43 is inserted into the corresponding first ground terminal hole of the substrate 32. Both the first power terminal hole and the first ground terminal hole are through holes that penetrate the substrate 32 in the thickness direction. The first power terminal hole constitutes the first power terminal connection portion. The first power terminal connection portion is the part of the substrate 32 to which the first power terminal 42 is connected.
[0036] The second end of the second power terminal 44 is inserted into the corresponding second power terminal hole of the circuit board 32. The second end of the second ground terminal 45 is inserted into the corresponding second ground terminal hole of the circuit board 32. Both the second power terminal hole and the second ground terminal hole are through holes that penetrate the circuit board 32 in the thickness direction. The second power terminal hole constitutes the second power terminal connection section. The second power terminal connection section is the portion of the circuit board 32 to which the second power terminal 44 is connected.
[0037] Multiple first signal terminals 46 are each inserted into corresponding first signal terminal holes in the substrate 32. Multiple second signal terminals 47 are each inserted into corresponding second signal terminal holes in the substrate 32. Both the first and second signal terminal holes are through holes that penetrate the substrate 32 in the thickness direction. The first signal terminal holes constitute the first signal terminal connection section. The first signal terminal connection section is the portion of the substrate 32 to which the first signal terminals 46 are connected. The second signal terminal holes constitute the second signal terminal connection section. The second signal terminal connection section is the portion of the substrate 32 to which the second signal terminals 47 are connected.
[0038] Multiple first motor terminals 23A are each inserted into corresponding first motor terminal holes in the substrate 32. Multiple second motor terminals 23B are each inserted into corresponding second motor terminal holes in the substrate 32. Both the first motor terminal holes and the second motor terminal holes are through holes that penetrate the substrate 32 in the thickness direction. The first motor terminal holes constitute the first motor terminal connection portion. The first motor terminal connection portion is the part of the substrate 32 to which the first motor terminals 23A are connected. The second motor terminal holes constitute the second motor terminal connection portion. The second motor terminal connection portion is the part of the substrate 32 to which the second motor terminals 23B are connected.
[0039] The circuit board 32 has an electrical circuit for supplying power to two winding groups of the motor 12. The electrical circuit includes, for example, two inverter circuits and two microcomputers. The first inverter circuit converts DC power from a DC power source into three-phase AC power to generate power to supply to the first winding group. The second inverter circuit converts DC power from a DC power source into three-phase AC power to generate power to supply to the second winding group. The microcomputers are, for example, chip-type integrated circuits. The first microcomputer controls the power supply to the first winding group via the first inverter circuit. The second microcomputer controls the power supply to the second winding group via the second inverter circuit.
[0040] The cover 33 is made of synthetic resin. The cover 33 is a box-shaped body with a rectangular cross-section. The cover 33 is open towards the motor 12. The cover 33 is attached to the housing 21 with the connector assembly 31 and the circuit board 32 attached, so as to cover the opening 21A of the housing 21.
[0041] <Heat Dissipation Structure of Motor Device 11> Next, the heat dissipation structure of the motor device 11 will be described. As shown in Figure 3, a part of the base 41A is positioned inside the fitting hole 21C. A sealing material 51 is interposed between the outer circumferential surface of the part of the base 41A that is positioned inside the fitting hole 21C and the inner circumferential surface of the fitting hole 21C. A sealing material 51 is also interposed between the flange portion 41F and the end wall of the protruding portion 21B. The sealing material 51 is, for example, a paste-like material that is filled into the gap between members to maintain waterproofness or airtightness. The sealing material may also function as an adhesive. The airtightness between the end wall of the protruding portion 21B and the body 41 is ensured by the sealing material 51.
[0042] The substrate 32 has a back surface and a front surface. The back surface is the surface of the substrate 32 facing the end wall of the protruding portion 21B in the axial direction of the motor 12. The front surface is the surface of the substrate 32 opposite to the back surface. Various electronic components are provided on the front and back surfaces of the substrate 32. The electronic components include a heat-generating element 32A that generates heat when energized. The heat-generating element 32A is provided, for example, on the front surface of the substrate 32. The heat-generating element 32A is positioned, for example, in the vicinity of the sealing material 51 when viewed from the axial direction of the motor 12. When viewed from the axial direction of the motor 12, a part of the heat-generating element 32A may overlap with a part of the sealing material 51.
[0043] A gap δ is formed in the axial direction of the motor 12 between the first end face of the extension part 22B and the end wall of the protruding part 21B. The second end face of the extension part 22B has a heat radiating part 22C. The heat radiating part 22C is a part of the extension part 22B that exchanges heat with the heat generating element 32A through the substrate 32. The second end face may have a concavo-convex shape according to the shape of the electronic component provided on the back surface of the substrate 32. That is, the heat radiating part 22C may be, for example, a columnar body having a rectangular cross-sectional shape and protruding from the second end face of the substrate 32 toward the substrate 32. The heat radiating part 22C faces the part of the substrate 32 where the heat generating element 32A is provided in the axial direction of the motor 12. A heat radiating material 52 is interposed between the heat radiating part 22C and the part of the substrate 32 where the heat generating element 32A is provided. The heat radiating material 52 is, for example, heat radiating grease. The heat radiating part 22C is maintained in a state of being in contact with the substrate 32 through the heat radiating material 52.
[0044] <Operation of the Present Embodiment> Next, the operation of the present embodiment will be described. As shown in FIG. 4, the heat generated by the heat generating element 32A is radiated to the extension part 22B through the substrate 32 and the heat radiating material 52. A gap δ is formed between the extension part 22B and the end wall of the protruding part 21B. That is, an air layer exists between the extension part 22B and the end wall of the protruding part 21B. Air has a lower thermal conductivity than a metal such as aluminum that forms the heat sink 22. In other words, a metal such as aluminum that forms the heat sink 22 has a smaller thermal resistance than air. Therefore, when viewed from the axial direction of the motor 12, even if the heat generating element 32A and the sealing material 51 are arranged close to each other, the heat generated by the heat generating element 32A being transmitted to the sealing material 51 through the end wall of the protruding part 21B is suppressed. The heat generated by the heat generating element 32A is efficiently radiated to the heat sink 22 having a smaller thermal resistance than air. Therefore, deterioration of the sealing material 51 due to heat is suppressed.
[0045] Furthermore, the heating element 32A is provided on the surface of the substrate 32. This makes it easier to secure space between the substrate 32 and the end wall of the protruding portion 21B. Consequently, it is possible to secure the thickness of the extension portion 22B in the axial direction of the motor 12, and thereby secure a sufficient volume of the extension portion 22B to dissipate the heat generated by the heating element 32A. In other words, since the heat capacity of the extension portion 22B is sufficiently secured, the heat generated by the heating element 32A is efficiently dissipated to the heat sink body 22A via the extension portion 22B.
[0046] <Comparative Example> As shown in Figure 5, if the extension portion 22B is not provided as the heat sink 22, the following heat dissipation structure is expected to be adopted. That is, the heat sink 22 consists only of the heat sink body 22A. For this reason, a heat dissipation portion 21D is provided on the end wall of the protruding portion 21B. The heat dissipation portion 21D is, for example, a columnar body having a rectangular cross-sectional shape, and protrudes from the end wall of the protruding portion 21B toward the substrate 32. The tip of the heat dissipation portion 21D faces the portion of the substrate 32 on which the heat-generating element 32A is provided in the axial direction of the motor 12. A heat dissipation material 52 is interposed between the tip of the heat dissipation portion 21D and the portion of the substrate 32 on which the heat-generating element 32A is provided. The tip of the heat dissipation portion 21D is maintained in contact with the substrate 32 via the heat dissipation material 52.
[0047] When this configuration is adopted, the heat generated by the heating element 32A is transmitted to the end wall of the protruding portion 21B via the substrate 32, the heat dissipation material 52, and the heat dissipation section 21D. Therefore, if the heating element 32A and the sealing material 51 are arranged in close proximity to each other when viewed from the axial direction of the motor 12, the heat generated by the heating element 32A is more easily transmitted to the sealing material 51 via the end wall of the protruding portion 21B. For this reason, from the viewpoint of suppressing the heat applied to the sealing material 51, it is preferable to provide an extension portion 22B as a heat sink 22 and dissipate the heat generated by the heating element 32A to the heat sink 22.
[0048] In addition, other heating elements 32B may be arranged in the area of the surface of the substrate 32 located directly above the heat sink 22. In this case, for example, the heat sink 22 is in contact with the portion of the substrate 32 where the other heating element 32B is provided via the heat dissipation material 52. The heat generated by the other heating element 32B is dissipated to the heat sink 22 via the substrate 32 and the heat dissipation material 52. This is the same in the present embodiment.
[0049] As shown in FIG. 6, particularly when the heating element 32A is provided on the back surface of the substrate 32, depending on the size of the heating element 32A, there may not be enough space between the substrate 32 and the end wall of the overhanging portion 21B. A heat dissipation material 52 is interposed between the substrate 32 and the end wall of the overhanging portion 21B. Therefore, it may not be possible to ensure the thickness of the end wall of the overhanging portion 21B in the axial direction of the motor 12, and there may not be enough volume of the end wall of the overhanging portion 21B to dissipate the heat generated by the heating element 32A. That is, since the heat capacity of the end wall of the overhanging portion 21B is not sufficiently ensured, the heat generated by the heating element 32A is likely to be transmitted to the sealing material 51. Therefore, from the viewpoint of suppressing the heat applied to the sealing material 51, it is preferable to provide the heating element 32A on the surface of the substrate 32 and ensure the thickness of the extension portion 22B, and thus the volume of the extension portion 22B, in the axial direction of the motor 12.
[0050] <Effect of the present embodiment> According to the present embodiment, the following effects can be obtained. (1) The motor device 11 includes a motor 12, a connector assembly 31, and a substrate 32. The motor 12 has a first end on the side where the output shaft 12B protrudes and a second end on the opposite side of the first end where the metal heat sink 22 is provided. The connector assembly 31 is arranged on the side of the motor 12 when viewed from the axial direction of the motor. The substrate 32 is arranged so as to overlap the heat sink 22 and the connector assembly 31 when viewed from the axial direction of the motor 12.
[0051] The second end of the motor 12 has a metal housing 21 that accommodates the portion of the heat sink 22 that is exposed from the second end. The housing 21 has an overhang 21B that extends laterally from the motor 12. A fitting hole 21C is provided in the end wall of the overhang 21, which penetrates the motor 12 in the axial direction. The connector assembly 31 is fitted into the fitting hole 31 via a sealing material 51.
[0052] The heat sink 22 has an extension 22B that extends from inside the housing 21 toward the fitting hole 21C. A heating element 32A, which is an electronic component that generates heat when energized, is provided in the region of the substrate 32 that overlaps with the extension 22B when viewed from the axial direction of the motor 12. The heating element 32A is in heat-transferable contact with the extension 22.
[0053] In this configuration, the heat generated by the heating element 32A is transferred to the extension 22B of the heat sink 22. Therefore, compared to, for example, the case where the heat generated by the heating element 32A is dissipated to the end wall of the protruding portion 21B, the transfer of heat to the sealing material 51 via the end wall of the protruding portion 21B is suppressed. Consequently, deterioration of the sealing material 51 due to heat is suppressed.
[0054] (2) The heat sink 22 only needs to be provided with an extension 22B. In other words, there is no need to add any special parts or configurations to the motor device 11 to suppress the heat applied to the sealing material 51. Therefore, the increase in the product cost of the motor device 11 due to the addition of parts or configurations is suppressed. In addition, the reliability of the sealing material 51 can be ensured without changing the assembly process of the motor device 11. The increase in the assembly cost of the motor device 11 is also suppressed.
[0055] (3) A gap δ is provided between the extension portion 22B and the end wall of the overhang portion 21B in the axial direction of the motor 12. With this configuration, an air layer is formed between the extension portion 22B and the end wall of the overhang portion 21B. Air has a lower thermal conductivity than the metal forming the heat sink 22. Therefore, the heat generated by the heat-generating element 32A is suppressed from being transmitted to the end wall of the overhang portion 21B via the extension portion 22B.
[0056] (4) The heating element 32A is positioned adjacent to the fitting hole 21C when viewed from the axial direction of the motor 12. The heating element 32A is positioned so as to overlap with the portion of the extension 22 that is closest to the fitting hole 21C when viewed from the axial direction of the motor 12. For example, when the heat generated by the heating element 32A is dissipated to the end wall of the protruding portion 21B, the closer the heating element 32A is to the fitting hole 21C when viewed from the axial direction of the motor 12, the easier it is for the heat generated by the heating element 32A to be transferred to the sealing material 51 via the end wall of the protruding portion 21B. In the motor device 11 of this embodiment, the heating element 32A is in heat-transferable contact with the extension 22. For this reason, even if the heating element 32A is positioned adjacent to the fitting hole 21C when viewed from the axial direction of the motor 12, the transfer of heat to the sealing material 51 via the end wall of the protruding portion 21 is suppressed.
[0057] (5) The heating element 32A is provided on the surface of the substrate 32 opposite to the extension 22B in the axial direction of the motor 12. The surface of the substrate 32 opposite to the extension 22B is the surface of the substrate 32. With this configuration, it is easier to secure the thickness, and therefore the volume, of the extension 22 in the axial direction of the motor 12 compared to the case where the heating element 32A is provided on the surface of the substrate 32 facing the extension 22B in the axial direction of the motor 12. As the heat capacity of the extension 22B is secured, the heat generated by the heating element 32A is efficiently dissipated to the heat sink body 22A via the extension 22B.
[0058] <Other Embodiments> This embodiment may be implemented with the following modifications: Case 12A may be a cylindrical body having a cross-sectional shape other than circular. Case 12A may be a cylindrical body having a square cross-sectional shape, for example.
[0059] - The heat dissipation material 52 may be omitted. In this case, the heat-generating element 32A will be in direct contact with the extension 22B. Since the heat sink 22 including the extension 22B is made of a metal with excellent thermal conductivity, the heat generated by the heat-generating element 32A is easily transferred to the heat sink body 22A via the extension 22B.
[0060] - The gap δ between the first end face of the extension 22B and the end wall of the overhang 21B may be eliminated. That is, the end walls of the extension 22B and the overhang 21B may be arranged to be in contact with each other in the axial direction of the motor 12. As shown by the dashed line in Figure 3, for example, the entire first end face of the extension 22B may be in contact with the end wall of the overhang 21B. As shown by the dashed line in Figure 4, for example, a part of the first end face of the extension 22B may be in contact with the end wall of the overhang 21B.
[0061] In this case, it is preferable that the thermal conductivity of the heat sink 22 is higher than that of the case 12A including the housing 21. For example, if the heat sink 22 is made of aluminum, the case 12A is made of iron. With this configuration, the heat generated by the heat generating element 32A is more easily transferred to the heat sink body 22A via the extension 22B, even if the first end face of the extension 22B is in contact with the end wall of the overhang 21B. Therefore, the transfer of heat generated by the heat generating element 32A to the end wall of the overhang 21B via the extension 22B is suppressed.
Claims
1. A motor device comprising: a motor having a first end on which an output shaft protrudes and a second end on the opposite side of the first end, on which a metal heat sink is provided; a connector assembly disposed to the side of the motor when viewed in the axial direction of the motor; and a substrate disposed to overlap the heat sink and the connector assembly when viewed in the axial direction of the motor, wherein the second end has a metal housing portion that accommodates the portion of the heat sink exposed from the second end, the housing portion has a protruding portion that extends to the side of the motor, the end wall of the protruding portion is provided with a fitting hole that penetrates in the axial direction of the motor, the connector assembly is configured to be fitted into the fitting hole via a sealing material, the heat sink has an extension portion that extends inside the housing portion toward the fitting hole, an electronic component configured to generate heat when energized is provided in the region of the substrate that overlaps with the extension portion when viewed in the axial direction of the motor, and the electronic component is configured to contact the extension portion in a heat transferable manner.
2. The motor device according to claim 1, wherein a gap is provided between the extension and the end wall of the overhang in the axial direction of the motor.
3. The motor device according to claim 1, wherein the end walls of the extension and the overhang are in contact with each other in the axial direction of the motor, and the thermal conductivity of the heat sink including the extension is higher than the thermal conductivity of the housing including the overhang.
4. The motor device according to any one of claims 1 to 3, wherein the electronic component is arranged adjacent to the fitting hole when viewed from the axial direction of the motor.
5. The motor device according to any one of claims 1 to 3, wherein the electronic component is provided on the surface of the substrate opposite to the extension in the axial direction of the motor.