Brushless motor

Abstract

To provide a brushless motor capable of preventing cooling air guided by a guide flow path from flowing into a gap between a cylindrical portion and a rotor housing and ensuring cooling air to be supplied to a cooling target including a stator, a heat sink, and a circuit board.SOLUTION: In a brushless motor 10, a motor holder 22 has an extending portion 62 that extends from a cylindrical portion 54 to an outside in a radial direction of the motor holder and is formed in a duct shape, an inlet 64 that opens toward one side in an axial direction of the motor holder and takes in cooling air is formed at a tip portion of the extending portion, and extends along the radial direction of the motor holder inside the extending portion. A guide passage 66 for guiding the cooling air taken in from the inlet to a main body 42 of a centerpiece 18 is formed, and a wall 68 extending along the radial direction of the motor holder and closing the gap between the inlet and a rotor housing 28 is provided inside the extending portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a brushless motor. [Background technology]

[0002] A conventional brushless motor includes a rotor having a cylindrical rotor housing with a top, a motor shaft disposed at the axial center of the rotor, a stator housed inside the rotor housing, a centerpiece having a main body facing an opening in the rotor housing and supporting the stator and motor shaft, a circuit board disposed on the opposite side of the main body from the stator, a heat sink disposed in the main body and connected to the circuit board so as to be heat transferable, and a motor holder having a cylindrical portion surrounding the rotor housing (see, for example, Patent Document 1). In this brushless motor, the motor holder has a duct-shaped extension portion extending radially outward from the cylindrical portion. An intake opening is formed at the tip of the extension portion, opening toward one axial side of the motor holder, for taking in cooling air. A guide channel is formed inside the extension portion, extending radially along the motor holder, for guiding the cooling air taken in from the intake opening toward the main body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3426151 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned brushless motor, the cooling air guided by the guide passage flows into the gap between the cylindrical portion and the rotor housing, which may result in a shortage of cooling air being supplied to the objects to be cooled, including the stator, heat sink, and circuit board.

[0005] The technology disclosed herein provides a brushless motor that can prevent cooling air guided by a guide flow path from flowing into the gap between the cylindrical portion and the rotor housing, thereby ensuring that cooling air is supplied to objects to be cooled, including the stator, heat sink, and circuit board. [Means for solving the problem]

[0006] The technology disclosed herein provides a motor holder (22) including a rotor (14) having a cylindrical rotor housing (28) with a top end, a motor shaft (12) provided at the axial center of the rotor, a stator (16) accommodated inside the rotor housing, a center piece (18) having a main body portion (42) facing an opening (28A) of the rotor housing and supporting the stator and the motor shaft, a circuit board (20) arranged on the opposite side of the main body portion from the stator, a heat sink (26) provided in the main body portion and connected to the circuit board so as to be capable of conducting heat, and a motor holder (22) having a cylindrical portion (54) surrounding the rotor housing. the motor holder has an extension portion (62) formed in a duct shape, extending from the cylindrical portion radially outward of the motor holder, an intake port (64) opening toward one axial side of the motor holder is formed at the tip of the extension portion and taking in cooling air, a guide flow path (66) extending along the radial direction of the motor holder is formed inside the extension portion and guiding the cooling air taken in from the intake port toward the main body portion, and a wall (68) extending along the radial direction of the motor holder and blocking the gap between the intake port and the rotor housing is provided inside the extension portion.

[0007] According to the technology of the present disclosure, a brushless motor is provided that can prevent the cooling air guided by the guide flow path from flowing into the gap between the cylindrical portion and the rotor housing, thereby ensuring that the cooling air is supplied to the objects to be cooled, including the stator, heat sink, and circuit board. [Brief explanation of the drawings]

[0008] [Figure 1]1 is a plan view of a brushless motor according to an embodiment of the technology of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 3 is an enlarged view of a main part of FIG. 2. [Figure 4] FIG. 3 is an enlarged view of a main part of FIG. 2. [Figure 5] FIG. 5 is a cross-sectional view taken along line BB in FIG. 4. [Figure 6] FIG. 5 is a cross-sectional view taken along line CC in FIG. 4. [Figure 7] 1 is a perspective view showing a main configuration of a brushless motor according to an embodiment of the disclosed technique; [Figure 8] 10 is an enlarged longitudinal cross-sectional view of a main portion of a brushless motor according to an embodiment of the disclosed technique, showing an aspect in which the gap between a cylindrical portion and a rotor housing is enlarged. FIG. [Figure 9] FIG. 2 is a perspective view showing the main configuration of a brushless motor according to a first comparative example. [Figure 10] FIG. 10 is a perspective view showing the main configuration of a brushless motor according to a second comparative example. [Figure 11] FIG. 11 is an enlarged longitudinal sectional view of a main part showing the main configuration of a brushless motor according to a third comparative example. [Figure 12] FIG. 11 is an enlarged longitudinal sectional view of a main portion of a brushless motor according to a third comparative example, showing an aspect in which the gap between the cylindrical portion and the rotor housing is enlarged. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the technology of the present disclosure will be described below.

[0010] The brushless motor 10 of this embodiment shown in Fig. 1 is a fan motor used in a blower mounted on a vehicle such as a passenger automobile. As shown in Fig. 2 and Fig. 3, the brushless motor 10 includes a motor shaft 12, a rotor 14, a stator 16, a center piece 18, a circuit board 20, a motor holder 22, a circuit case 24, and a heat sink 26. In each figure, arrow Z1 indicates one axial side of the brushless motor 10, and arrow Z2 indicates the other axial side of the brushless motor 10.

[0011] The rotor 14 has a cylindrical rotor housing 28 with an opening 28A and a rotor magnet 30 fixed to the inside of the peripheral wall of the rotor housing 28. A cylindrical fixing portion 32 is formed in the center of the ceiling of the rotor housing 28, and the motor shaft 12 is press-fitted into the inside of the fixing portion 32. The motor shaft 12 is press-fitted into the inside of the fixing portion 32, thereby being provided at the axial center of the rotor 14. The tip of the motor shaft 12 protrudes from the rotor housing 28 to one axial side of the brushless motor 10.

[0012] The stator 16 is housed inside the rotor housing 28. The stator 16 is disposed radially inside the rotor magnet 30 and facing the rotor magnet 30. The stator 16 has a stator core 34 and a plurality of windings 36. The plurality of windings 36 are wound around a plurality of teeth 38 formed radially on the stator core 34, with a resin insulator 40 interposed between them. The entire stator 16, including the stator core 34 and the plurality of windings 36, forms an annular shape.

[0013] Center piece 18 is made of resin. Center piece 18 has a main body 42 facing opening 28A of rotor housing 28, a cylindrical support portion 44 protruding from the center of main body 42 toward stator 16, and a cylindrical support member 46 attached to support portion 44 from one axial side of brushless motor 10. Main body 42 is formed in a roughly disk shape with its thickness direction aligned with the axial direction of brushless motor 10. Main body 42 is sized to face the entire opening 28A of rotor housing 28.

[0014] The support portion 44 and the support member 46 are inserted inside the annular stator core 34. The stator core 34 is fixed to the main body portion 42, for example, by screws, so that the stator 16 is supported by the centerpiece 18. A bearing accommodating portion 48 is formed in the main body portion 42, and a bearing accommodating portion 50 is formed in the support member 46. A bearing 52 is accommodated in each of the bearing accommodating portions 48, 50, and the motor shaft 12 is press-fitted into the bearing 52. The motor shaft 12 is supported by the support portion 44 and the support member 46 via the bearing 52, so that the rotor 14 is rotatably supported with respect to the centerpiece 18.

[0015] The circuit board 20 is disposed on the opposite side of the main body 42 from the stator 16. The circuit board 20 is fixed to the main body 42, for example, by screws. A plurality of switching elements are mounted on the circuit board 20 to switch the current supplied to the plurality of windings 36. The current supplied to the plurality of windings 36 is switched by the plurality of switching elements, thereby forming a rotating magnetic field in the stator 16. Furthermore, the formation of the rotating magnetic field in the stator 16 causes attractive and repulsive forces to act between the stator 16 and the rotor 14, causing the rotor 14 to rotate.

[0016] The motor holder 22 is made of, for example, resin, and is provided around the rotor housing 28. The motor holder 22 has a cylindrical portion 54 that surrounds the rotor housing 28, and an annular portion 56 that extends radially outward from the cylindrical portion 54 of the motor holder 22. A gap 58 is provided between the cylindrical portion 54 and the rotor housing 28 in the radial direction of the brushless motor 10. The annular portion 56 is formed in the shape of an annular plate with its thickness direction aligned with the axial direction of the brushless motor 10. A plurality of mounting portions 60 are provided on the outer periphery of the annular portion 56. The brushless motor 10 is fixed to the object by attaching the plurality of mounting portions 60 to the object.

[0017] The circuit case 24 is formed in a flat container shape and is attached to the main body 42 with its opening facing the main body 42. The circuit case 24 is disposed on the opposite side of the main body 42 from the stator 16, and houses the circuit board 20. The circuit case 24 is fixed to the motor holder 22 by, for example, screws.

[0018] The motor holder 22 has an extension portion 62 that extends from the cylindrical portion 54 radially outward of the brushless motor 10. The extension portion 62 is formed in a duct shape. An intake port 64 is formed at the tip of the extension portion 62 for taking in cooling air W. The intake port 64 is located outside the main body portion 42 in the radial direction of the brushless motor 10 and opens toward one axial side of the brushless motor 10. The radial direction of the brushless motor 10 is the same as the radial direction of the motor holder 22, and the axial direction of the brushless motor 10 is the same as the axial direction of the motor holder 22. A guide flow path 66 is formed inside the extension portion 62 and extends along the radial direction of the brushless motor 10. The guide flow path 66 extends from the intake port 64 toward the main body portion 42 and guides the cooling air W.

[0019] A wall 68 extending radially of the brushless motor 10 is provided inside the extension portion 62. The wall 68 is provided between the intake 64 and the rotor housing 28 in the radial direction of the brushless motor 10, and closes the gap between the intake 64 and the rotor housing 28. Because the rotor 14 including the rotor housing 28 rotates, a small gap is provided between the wall 68 and the rotor housing 28. The gap between the wall 68 and the rotor housing 28 is set to the smallest possible gap so that the rotor housing 28 does not interfere with the wall 68 during rotation. The wall 68 extends from the intake 64 side to a position opposite the end of the rotor housing 28 on the opening 28A side. The wall 68 forms a wall portion on one axial side of the brushless motor 10 relative to the guide flow passage 66, and the bottom of the extension portion 62 forms a wall portion on the other axial side of the brushless motor 10 relative to the guide flow passage 66.

[0020] The annular portion 56 is formed between the intake port 64 and the cylindrical portion 54 in the radial direction of the brushless motor 10, and is formed integrally with the extension portion 62. The annular portion 56 is located on one axial side of the brushless motor 10 relative to the wall 68, and a space 70 is provided between the wall 68 and the annular portion 56 in the axial direction of the brushless motor 10.

[0021] The heat sink 26 is made of a metal such as aluminum that has high thermal conductivity. The heat sink 26 is fixed to the circuit board 20 by screws or the like. The heat sink 26 is connected to the circuit board 20 in a manner that allows heat to be transferred therethrough. Specifically, the heat sink 26 is connected to a plurality of switching elements and the like on the circuit board 20 in a manner that allows heat to be transferred therethrough.

[0022] As shown in Figures 4 to 7, the heat sink 26 is provided on the main body 42. The heat sink 26 extends along the periphery of the motor shaft 12 (see Figure 6 in particular). The heat sink 26 is C-shaped when viewed in the axial direction of the brushless motor 10. The main body 42 has a ceiling 72 that covers the heat sink 26 from the stator 16 side. The ceiling 72 also extends along the periphery of the motor shaft 12 in correspondence with the heat sink 26, and is C-shaped when viewed in the axial direction of the brushless motor 10. The ceiling 72 is formed along the periphery of the support part 44.

[0023] A cooling air flow path 74 is formed between the heat sink 26 and the ceiling portion 72, and the cooling air W is guided to the cooling air flow path 74 by the guide flow path 66. In addition, the wall 68 prevents the cooling air W taken in from the intake 64 from flowing into the gap 58 between the cylindrical portion 54 and the rotor housing 28, and guides the cooling air W to the cooling air flow path 74 between the heat sink 26 and the ceiling portion 72.

[0024] More specifically, the heat sink 26 has a facing portion 76 and multiple protrusions 78. The facing portion 76 faces the ceiling portion 72 in the axial direction of the main body portion 42. The multiple protrusions 78 protrude from the facing portion 76 toward the ceiling portion 72 and are arranged in the cooling air flow path 74 between the heat sink 26 and the ceiling portion 72 (more specifically, between the facing portion 76 and the ceiling portion 72).

[0025] A plurality of through holes 80 are formed in the ceiling portion 72. Each through hole 80 penetrates the main body portion 42 in the axial direction and communicates with the cooling air flow path 74. The axial direction of the main body portion 42 is the same as the axial direction of the brushless motor 10. Each through hole 80 is formed at a position corresponding to a slot (not shown) between adjacent teeth 38.

[0026] A connector section 82 is provided on the main body section 42. The connector section 82 is configured to include a connector case, connector terminals, etc. A partition wall 84 is provided on the main body section 42 to separate the cooling air flow path 74 from the connector section 82. The partition wall 84 is formed in a concave shape along the inside of the recess (i.e., the opening of the C) of the ceiling section 72, which is C-shaped when viewed in the axial direction of the brushless motor 10.

[0027] The main body 42 has a plurality of openings 86. The plurality of openings 86 are formed on the outer periphery of the main body 42. The plurality of openings 86 communicate with the cooling air flow path 74 and open radially outward from the main body 42. The radial direction of the main body 42 is the same as the radial direction of the brushless motor 10.

[0028] In the brushless motor 10, the mounting angle of the motor holder 22 relative to the center piece 18 is changeable. That is, by selectively connecting any one of the plurality of openings 86 to the guide flow path 66, the mounting angle of the motor holder 22 relative to the center piece 18 can be changed. Depending on the mounting angle of the motor holder 22 relative to the center piece 18, any one of the plurality of openings 86 communicates with the guide flow path 66. The remaining openings 86 of the plurality of openings 86 are blocked by blocking portions 88 provided on the motor holder 22.

[0029] Radial ribs 90 extending radially are formed on the ceiling portion 72. The radial ribs 90 extend from the ceiling portion 72 to one axial side of the brushless motor 10. The ceiling portion 72 is spaced apart from the support portion 44 in the radial direction of the brushless motor 10, and connecting ribs 92 that connect the ceiling portion 72 and the support portion 44 are formed radially between the ceiling portion 72 and the support portion 44 in the radial direction of the brushless motor 10.

[0030] Next, the effects of this embodiment will be described.

[0031] First, to clarify the effects of this embodiment, a comparative example will be described. As shown in Fig. 9, in the first comparative example, the ceiling portion 72 (see Fig. 7, etc.) is omitted from the main body portion 42, unlike this embodiment. However, when the ceiling portion 72 is omitted, the cooling air W is diffused, and therefore the cooling air W is supplied from the guide flow path 66 to only a part of the heat sink 26, and there is a risk that the cooling air W will not reach the entire heat sink 26.

[0032] In contrast, in this embodiment, the main body 42 has a ceiling portion 72 that covers the heat sink 26 from the side of the stator 16, and the guide flow path 66 guides the cooling air W taken in from the intake 64 to a cooling air flow path 74 between the heat sink 26 and the ceiling portion 72. Therefore, because the ceiling portion 72 can suppress diffusion of the cooling air W, the cooling air W can be distributed throughout the entire heat sink 26 even when the heat sink 26 extends along the periphery of the motor shaft 12.

[0033] Moreover, the heat sink 26 has an opposing portion 76 that faces the ceiling portion 72 in the axial direction of the main body 42, and a plurality of protrusions 78 that protrude from the opposing portion 76 toward the ceiling portion 72 and are disposed in the cooling air flow path 74. Therefore, the cooling air W hits the plurality of protrusions 78, thereby improving the cooling performance of the heat sink 26.

[0034] Additionally, the ceiling portion 72 is formed with a plurality of through holes 80 that communicate with the cooling air flow path 74 and penetrate the main body portion 42 in the axial direction. Therefore, the cooling air W flowing through the cooling air flow path 74 can be discharged to the stator 16 side via the plurality of through holes 80. This allows the stator 16 to be cooled.

[0035] Furthermore, the main body 42 is provided with a partition wall 84 that separates the cooling air flow path 74 from the connector 82. This prevents the cooling air W flowing through the cooling air flow path 74 from leaking into the connector 82.

[0036] The motor holder 22 also has a plurality of openings 86 that can selectively communicate with the guide flow passage 66. Therefore, by selectively connecting any one of the plurality of openings 86 with the guide flow passage 66, the mounting angle of the motor holder 22 with respect to the center piece 18 can be changed.

[0037] 10, the blocking portion 88 is omitted from this embodiment. However, when the blocking portion 88 is omitted, the cooling air W flowing through the cooling air flow path 74 leaks out through the remaining opening 86.

[0038] In contrast to this, in this embodiment, the remaining openings 86 are blocked by the blocking portions 88. Therefore, the cooling air W flowing through the cooling air flow path 74 can be prevented from leaking through the remaining openings 86.

[0039] Furthermore, radial ribs 90 extending radially are formed on the ceiling portion 72. Therefore, the rigidity of the ceiling portion 72 can be ensured.

[0040] Furthermore, a plurality of connecting ribs 92 are formed between the ceiling portion 72 and the support portion 44, connecting the ceiling portion 72 and the support portion 44. Therefore, the rigidity of the ceiling portion 72 and the support portion 44 can be ensured.

[0041] In a third comparative example shown in Fig. 11 , the wall 68 is omitted from this embodiment. However, if the wall 68 is omitted, the cooling air W guided by the guide flow path 66 flows into the gap 58 between the cylindrical portion 54 and the rotor housing 28, and the cooling air W leaks to the outside through the gap 58, which may result in a shortage of cooling air W supplied to the objects to be cooled, including the stator 16, the heat sink 26, and the circuit board 20. In particular, as shown in Fig. 12 , if the gap 58 between the cylindrical portion 54 and the rotor housing 28 is large, the amount of cooling air W flowing into the gap 58 between the cylindrical portion 54 and the rotor housing 28 increases.

[0042] In contrast, in this embodiment, a wall 68 extending radially of the motor holder 22 is provided inside the extension portion 62, and the wall 68 blocks the gap between the intake 64 and the rotor housing 28. This prevents the cooling air W guided by the guide flow path 66 from flowing into the gap 58 between the cylindrical portion 54 and the rotor housing 28, ensuring that the cooling air W is supplied to the objects to be cooled, including the stator 16, the heat sink 26, and the circuit board 20. In particular, as shown in FIG. 8 , even when the gap 58 between the cylindrical portion 54 and the rotor housing 28 is large, the cooling air W can be prevented from flowing into the gap 58, which is very effective.

[0043] Furthermore, the wall 68 guides the cooling air W taken in from the intake 64 to the cooling air flow path 74 between the heat sink 26 and the ceiling portion 72. Therefore, the guide flow path 66 prevents the cooling air W from being guided inside the rotor housing 28, and the cooling air W can be supplied from the guide flow path 66 to the heat sink 26.

[0044] Furthermore, an annular portion 56 is located on one axial side of the wall 68 of the motor holder 22 between the intake port 64 and the cylindrical portion 54, and is formed integrally with the extending portion 62. The annular portion 56 extends radially outward from the cylindrical portion 54 of the motor holder 22, and a space 70 is provided between the wall 68 and the annular portion 56 in the axial direction of the motor holder 22. Therefore, compared to when the wall 68 and the annular portion 56 are formed integrally without the space 70, the wall 68 and the annular portion 56 can each be made thinner. This makes it possible to prevent sink marks in the resin on the wall 68 and the annular portion 56 when the motor holder 22 is formed by resin molding.

[0045] The above describes one embodiment of the technology of the present disclosure, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modifications within the scope of the gist of the present disclosure.

[0046] Below, supplementary notes are provided regarding the technology of the present disclosure. (Appendix 1) a rotor (14) having a cylindrical rotor housing (28); a motor shaft (12) provided at the axial center of the rotor; a stator (16) housed inside the rotor housing; a center piece (18) having a body portion (42) facing the opening (28A) of the rotor housing and supporting the stator and the motor shaft; a circuit board (20) disposed on the opposite side of the main body from the stator; a heat sink (26) provided in the main body and connected to the circuit board so as to be capable of conducting heat; a motor holder (22) having a cylindrical portion (54) surrounding the rotor housing; Equipped with the motor holder has an extension portion (62) formed in a duct shape and extending radially outward from the cylindrical portion of the motor holder, an intake port (64) that opens toward one axial side of the motor holder and takes in cooling air is formed at the tip of the extension portion; A guide flow path (66) is formed inside the extension portion, extending along the radial direction of the motor holder and guiding the cooling air taken in from the intake port toward the main body portion, A wall (68) is provided inside the extension portion, extending along the radial direction of the motor holder and closing the gap between the intake port and the rotor housing. Brushless motor (10). (Appendix 2) The heat sink extends around the motor shaft, The main body has a ceiling portion (72) that covers the heat sink from the stator side, The wall guides the cooling air taken in from the intake port to a cooling air flow path (74) between the heat sink and the ceiling portion. 2. The brushless motor according to claim 1. (Appendix 3) a ring portion (56) is formed integrally with the extension portion between the intake port and the cylindrical portion, the ring portion (56) being located on one axial side of the motor holder relative to the wall and extending from the cylindrical portion toward the radially outward side of the motor holder; a space (70) is provided between the wall and the annular portion in the axial direction of the motor holder; 10. The brushless motor according to claim 1 or 2. [Explanation of symbols]

[0047] 10...brushless motor, 12...motor shaft, 14...rotor, 16...stator, 18...center piece, 20...circuit board, 22...motor holder, 24...circuit case, 26...heat sink, 28...rotor housing, 28A...opening, 30...rotor magnet, 32...fixed portion, 34...stator core, 36...winding, 38...teeth, 40...insulator, 42...main body, 44...support portion, 46...support member, 48...bearing accommodating portion, 50...bearing accommodating portion, 52...bearing, 54...cylindrical portion, 56...annular portion, 58...gap, 60...mounting portion, 62...extending portion, 64...inlet, 66...guide flow passage, 68...wall, 70...space, 72...ceiling portion, 74...cooling air flow passage, 76...opposing portion, 78...projection portion, 80...through hole, 82...connector portion, 84...partition wall, 86...opening, 88...blocking portion, 90...radiating rib, 92...connecting rib

Claims

1. a rotor (14) having a cylindrical rotor housing (28); a motor shaft (12) provided at the axial center of the rotor; a stator (16) housed inside the rotor housing; a center piece (18) having a body portion (42) facing the opening (28A) of the rotor housing and supporting the stator and the motor shaft; a circuit board (20) disposed on the opposite side of the main body from the stator; a heat sink (26) provided on the main body and connected to the circuit board in a heat conductive manner; a motor holder (22) having a cylindrical portion (54) surrounding the rotor housing; Equipped with the motor holder has an extension portion (62) formed in a duct shape, extending from the cylindrical portion to the outside in the radial direction of the motor holder, An intake port (64) that opens toward one axial side of the motor holder and takes in cooling air is formed at the tip of the extension portion, A guide flow path (66) is formed inside the extension portion, extending along the radial direction of the motor holder and guiding the cooling air taken in from the intake port toward the main body portion, A wall (68) is provided on the inside of the extension portion, extending along the radial direction of the motor holder and closing the gap between the intake port and the rotor housing. A brushless motor (10).

2. The heat sink extends around the motor shaft, The main body portion has a ceiling portion (72) that covers the heat sink from the stator side, The wall guides the cooling air taken in from the intake port to a cooling air flow path (74) between the heat sink and the ceiling portion.

2. The brushless motor according to claim 1.

3. a ring portion (56) is formed integrally with the extension portion between the intake port and the cylindrical portion, the ring portion being located on one axial side of the motor holder relative to the wall and extending from the cylindrical portion toward the radially outward side of the motor holder; a space (70) is provided between the wall and the annular portion in the axial direction of the motor holder; 3. The brushless motor according to claim 1 or 2.

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