Electric motor and outdoor unit

Abstract

One form of an electric motor according to the present disclosure comprises: a rotor that is rotatable about a central axis; a shaft that extends in an axial direction and is rotatable about the central axis together with the rotor; a stator that is disposed on the radially outer side of the rotor and faces the rotor with a gap therebetween in the radial direction; a bearing that rotatably supports a portion of the shaft on one side in the axial direction relative to the rotor; a bearing holding part that holds the bearing; a circuit board disposed on one side in the axial direction relative to the bearing holding part; and a housing that internally accommodates each of the rotor, the stator, the bearing holding part, and the circuit board. The housing is of cylindrical shape surrounding the central axis and extending in the axial direction. The housing has: a motor frame having an opening that opens on one side in the axial direction; and a heat-dissipating part that occupies the opening. At least a part of the stator is embedded in the motor frame. The circuit board is held in place by the bearing holding part and the heat-dissipating part.

Description

Electric motor and outdoor unit

[0001] The present disclosure relates to an electric motor and an outdoor unit.

[0002] As a fan motor included in an outdoor unit of a refrigeration cycle apparatus, an electric motor is disclosed in which each of a stator and a wiring board is covered by a cover portion formed of a resin material (see, for example, Patent Document 1).

[0003] International Publication No. 2020 / 178927

[0004] Generally, electronic components including power semiconductor elements that generate current supplied to the stator are mounted on the wiring board. Since the heat generation amount of the power semiconductor element is larger than the heat generation amount of other electronic components, it greatly contributes to the temperature rise of the wiring board. In the above electric motor, since the wiring board is covered by the cover portion, it is difficult to reduce the thermal resistance between the wiring board and the heat dissipation member even if a heat dissipation member such as a heat sink is arranged around the wiring board. Therefore, it is difficult to increase the amount of heat transferred from the wiring board to the heat dissipation member, and thus it is difficult to increase the amount of heat dissipated from the wiring board to the outside of the electric motor. Therefore, it is difficult to suppress the temperature of the wiring board from becoming too high.

[0005] In view of the above circumstances, an object of the present disclosure is to provide an electric motor and an outdoor unit capable of suppressing the temperature of the circuit board from becoming too high.

[0006] One embodiment of the electric motor according to the present disclosure comprises: a rotor rotatable about a central axis extending in the axial direction; a shaft extending in the axial direction along the central axis and rotatable together with the rotor about the central axis; a stator positioned radially outside the rotor with respect to the central axis and facing the rotor at a radial distance; a bearing rotatably supporting a portion of the shaft on one side in the axial direction relative to the rotor; a bearing holder for holding the bearing; a circuit board positioned on one side in the axial direction relative to the bearing holder; and a housing that houses the rotor, the stator, the bearing holder, and the circuit board inside, wherein the housing is cylindrical, surrounding the central axis and extending in the axial direction, and has a motor frame with an opening that opens on one side in the axial direction, and a heat dissipation portion that closes the opening, at least a portion of the stator being embedded in the motor frame, and the circuit board being held between the bearing holder and the heat dissipation portion.

[0007] One embodiment of the outdoor unit according to this disclosure comprises the above-mentioned electric motor, a blower fan that is rotationally driven by the electric motor, and a heat exchanger through which the airflow generated by the blower fan passes.

[0008] According to this disclosure, it is possible to suppress the temperature of the circuit board in the electric motor and the outdoor unit from becoming too high.

[0009] This is a schematic diagram showing the general configuration of the refrigeration cycle device in the embodiment. This is a perspective view showing the outdoor unit in the embodiment. This is a cross-sectional view showing the outdoor unit in the embodiment, taken along the line III-III in Figure 2. This is a perspective view showing the electric motor in the embodiment. This is a cross-sectional view showing the electric motor in the embodiment. This is a first perspective view showing a part of the electric motor in the embodiment. This is a second perspective view showing a part of the electric motor in the embodiment. This is a partially enlarged cross-sectional view showing a part of the electric motor in the embodiment. This is a third perspective view showing a part of the electric motor in the embodiment. This is a fourth perspective view showing a part of the electric motor in the embodiment. This is a perspective view showing the rotor in the embodiment. This is a perspective view showing the holding member in the embodiment. This is a cross-sectional view of the electric motor in the embodiment, taken along the line XIII-XIII in Figure 5.

[0010] Embodiments of this disclosure will be described below with reference to the drawings. However, the scope of this disclosure is not limited to the embodiments described below, and can be modified at will within the scope of the technical concept of this disclosure. Furthermore, in the following drawings, the scale and number of components in each structure may differ from those in the actual structure in order to make each component easier to understand.

[0011] The X-axis is shown in the drawings as appropriate. The X-axis is the front-to-back direction of the outdoor unit 10. The X-axis is also the direction in which the central axis J of the electric motor 30 extends. In this embodiment, the central axis J is a virtual axis. In the following description, the direction in which the central axis J extends, that is, the direction parallel to the X-axis, is referred to as the "axial direction" or "front-to-back direction". The radial direction centered on the central axis J is simply referred to as the "radial direction". The side of the radial direction that moves away from the central axis J is referred to as the "outer radial direction". The side of the radial direction that moves closer to the central axis J is referred to as the "inner radial direction". The circumferential direction centered on the central axis J is simply referred to as the "circumferential direction". In the following description, the side of the axial direction in which the X-axis arrow points (+X side) is referred to as the "one side of the axial direction" or "rear side". The side of the axial direction opposite to the side in which the X-axis arrow points (-X side) is referred to as the "other side of the axial direction" or "front side".

[0012] The circumferential direction is indicated by the arrow θ in each diagram. The side of the circumferential direction in which the arrow θ points (the +θ side) is called "one side of the circumferential direction." The side of the circumferential direction opposite to the side in which the arrow θ points (the -θ side) is called "the other side of the circumferential direction." One side of the circumferential direction is the side that proceeds clockwise around the central axis J when viewed from one side in the axial direction. The other side of the circumferential direction is the side that proceeds counterclockwise around the central axis J when viewed from one side in the axial direction.

[0013] The Y-axis is shown in the drawings as appropriate. The Y-axis represents the left-right direction of the outdoor unit 10 and the electric motor 30. The left-right direction intersects with the axial direction. In this embodiment, the left-right direction is perpendicular to the axial direction. In the following description, the side of the left-right direction to which the Y-axis arrow points (+Y side) will be referred to as the "left side". The side of the left-right direction opposite to the side to which the Y-axis arrow points (-Y side) will be referred to as the "right side".

[0014] The Z-axis is shown in the drawings as appropriate. The Z-axis is the vertical direction. In this embodiment, the vertical direction is perpendicular to both the left-right direction and the axial direction. The vertical direction does not have to be perpendicular to at least one of the left-right direction and the axial direction. In the following description, the side of the vertical direction to which the Z-axis arrow points (+Z side) will be referred to as the "upper side". The side of the vertical direction opposite to the side to which the Z-axis arrow points (-Z side) will be referred to as the "lower side". Note that the left side, right side, upper side, and lower side are merely names used to describe the relative positional relationship of each part, and the actual arrangement may be different from the arrangement indicated by these names.

[0015] Figure 1 is a schematic diagram showing the general configuration of the refrigeration cycle device 100 in the embodiment. Figure 2 is a perspective view showing the outdoor unit 10 in the embodiment. Figure 3 is a cross-sectional view showing the outdoor unit 10 in the embodiment, and is a cross-sectional view taken along line III-III in Figure 2. In the embodiment, the refrigeration cycle device 100 shown in Figure 1 is an air conditioner. The refrigeration cycle device 100 comprises an outdoor unit 10, an indoor unit 20, and a circulation path section 18. The outdoor unit 10 is located outdoors. The indoor unit 20 is located indoors. The outdoor unit 10 and the indoor unit 20 are connected to each other by a circulation path section 18 through which refrigerant 19 circulates. The refrigeration cycle device 100 adjusts the temperature of the indoor air by performing heat exchange between the refrigerant 19 circulating in the circulation path section 18 and the air in the room where the indoor unit 20 is located. As the refrigerant 19, a fluorine-based refrigerant or a hydrocarbon-based refrigerant with a low global warming potential can be used.

[0016] The outdoor unit 10 comprises a housing 11, a compressor 12, a heat exchanger 13, a flow control valve 14, a blower fan 15, an electric motor 30, a four-way valve 16, and a control unit 17. The compressor 12, heat exchanger 13, flow control valve 14, blower fan 15, electric motor 30, four-way valve 16, and control unit 17 are housed inside the housing 11. The compressor 12, heat exchanger 13, flow control valve 14, and four-way valve 16 are each provided in the portion of the circulation path 18 located inside the housing 11. The compressor 12, heat exchanger 13, flow control valve 14, and four-way valve 16 are each connected by the portion of the circulation path 18 located inside the housing 11.

[0017] The four-way valve 16 is installed in the part of the circulation path 18 that is connected to the discharge side of the compressor 12. The four-way valve 16 reverses the direction in which the refrigerant 19 circulates within the circulation path 18 by switching a part of the circulation path 18. If the path connected to the four-way valve 16 is the path shown by the solid line on the four-way valve 16 in Figure 1, the refrigerant 19 flows within the circulation path 18 in the direction shown by the solid arrow in Figure 1. If the path connected to the four-way valve 16 is the path shown by the dashed line on the four-way valve 16 in Figure 1, the refrigerant 19 flows within the circulation path 18 in the direction shown by the dashed arrow in Figure 1.

[0018] The indoor unit 20 comprises a housing 21, a heat exchanger 22, a blower fan 23, and a control device 24. The heat exchanger 22, blower fan 23, and control device 24 are housed inside the housing 21. The indoor unit 20 performs cooling operation to cool the indoor air and heating operation to heat the indoor air.

[0019] When the indoor unit 20 is operating in cooling mode, the refrigerant 19 flowing through the circulation path 18 flows in the direction indicated by the solid arrow in Figure 1. That is, the refrigerant 19 flowing through the circulation path 18 passes through the compressor 12, the heat exchanger 13 of the outdoor unit 10, the flow control valve 14, and the heat exchanger 22 of the indoor unit 20 in that order, and returns to the compressor 12. In cooling mode, the heat exchanger 13 of the outdoor unit 10 functions as a condenser, and the heat exchanger 22 of the indoor unit 20 functions as an evaporator.

[0020] When the indoor unit 20 is operating in heating mode, the refrigerant 19 flowing through the circulation path 18 flows in the direction shown by the dashed line in Figure 1. In other words, the refrigerant 19 flowing through the circulation path 18 passes through the compressor 12, the heat exchanger 22 of the indoor unit 20, the flow control valve 14, and the heat exchanger 13 of the outdoor unit 10 in that order, and returns to the compressor 12. In heating mode, the heat exchanger 13 of the outdoor unit 10 functions as an evaporator, and the heat exchanger 22 of the indoor unit 20 functions as a condenser.

[0021] Next, the outdoor unit 10 of the embodiment will be described in detail. As shown in Figure 2, the housing 11 is a roughly rectangular box shape. As shown in Figure 3, the housing 11 has a front panel 11a that covers the internal space of the housing 11 from the front (-X side), a rear panel 11d that covers the internal space of the housing 11 from the rear (+X side), a top plate 11t that covers the internal space of the housing 11 from above, and a bottom plate 11c that covers the internal space of the housing 11 from below.

[0022] A fan grille 11G is attached to the front panel 11a. The fan grille 11G covers the front opening 11b provided in the front panel 11a from the front. The front opening 11b is a hole that penetrates the front panel 11a in the front-to-back direction (X-axis direction). In this embodiment, when viewed from the front, the front opening 11b is substantially circular in shape.

[0023] The housing 11 houses a heat exchanger 13, a blower fan 15, an electric motor 30, and an electric motor holder 27. Although not shown in the illustration, the housing 11 also houses a compressor 12, a flow control valve 14, a four-way valve 16, and a control unit 17. The electric motor holder 27 is plate-shaped and extends vertically (Z-axis direction). The plate surface of the electric motor holder 27 faces forward and backward (X-axis direction). Although not shown in the illustration, when viewed from the front and rear, the electric motor holder 27 is roughly rectangular with its longest side extending vertically. The left-right dimension (Y-axis direction) of the electric motor holder 27 is smaller than the left-right dimension of the housing 11. The upper end of the electric motor holder 27 is fixed to the top plate 11t, and the lower end of the electric motor holder 27 is fixed to the bottom plate 11c. In this way, the electric motor holder 27 is fixed to the housing 11.

[0024] The heat exchanger 13 is located behind (towards the +X side of) the motor holder 27. As described above, the circulation path section 18 (see Figure 1) is connected to the heat exchanger 13. A refrigerant flows inside the heat exchanger 13. An airflow A generated by the blower fan 15 passes through the heat exchanger 13.

[0025] The blower fan 15 is positioned between the front panel 11a and the motor holder 27. The blower fan 15 has a cylindrical portion 15a and a plurality of rotating blades 15b. The cylindrical portion 15a is substantially cylindrical in shape, extending in the front-rear direction (X-axis direction) with respect to the central axis J. The cylindrical portion 15a has openings on both sides in the front-rear direction. Each of the plurality of rotating blades 15b is a curved plate shape that protrudes radially outward from the outer circumferential surface of the cylindrical portion 15a. Each rotating blade 15b is spaced apart from each other in the circumferential direction. Each rotating blade 15b faces the front opening 11b in the front-rear direction.

[0026] The electric motor 30 rotates the blower fan 15 around the central axis J. In this embodiment, the electric motor 30 is an electric motor. The shaft 53 of the electric motor 30 is substantially cylindrical and extends along the central axis J. The shaft 53 passes through the inside of the cylindrical portion 15a in the front-rear direction. The shaft 53 is fixed to the cylindrical portion 15a.

[0027] When the electric motor 30 rotates the shaft 53 around the central axis J, the blower fan 15 rotates around the central axis J. In other words, the blower fan 15 is rotationally driven by the electric motor 30. As each rotor blade 15b rotates around the central axis J, air flows into the housing 11 from the air intake 11f provided on the rear panel 11d. This creates an airflow A that flows from the rear (+X side) to the front (-X side) by the blower fan 15. The airflow A passes through the heat exchanger 13 and the rotor blades 15b and is blown out to the front of the housing 11 through the front opening 11b. This increases the heat exchange efficiency in the heat exchanger 13.

[0028] Figure 4 is a perspective view showing the electric motor 30 in the embodiment. Figure 5 is a cross-sectional view showing the electric motor 30 in the embodiment. Figure 6 is a first perspective view showing a part of the electric motor 30 in the embodiment. Next, the electric motor 30 in the embodiment will be described. The electric motor 30 in the embodiment shown in Figure 4 is an electric motor. As described above, the electric motor 30 rotates the blower fan 15. As shown in Figure 5, the electric motor 30 includes a housing 31, a rotor 50, a shaft 53, a stator 60, a retaining member 66, a bearing retaining part 70, a circuit board 76, and bearings 91, 92.

[0029] The housing 31 houses the various components of the electric motor 30, such as the rotor 50, stator 60, bearing holder 70, and circuit board 76. As shown in Figure 4, the housing 31 is substantially cylindrical, extending axially around the central axis J. The housing 31 may also have other shapes, such as a rectangular tube extending axially. The housing 31 includes a motor frame 32 and a heat dissipation section 40.

[0030] As shown in Figure 5, the motor frame 32 is cylindrical, extending axially around the central axis J. In this embodiment, the motor frame 32 is substantially cylindrical, extending axially with the central axis J as its center. The motor frame 32 may also have other shapes, such as a rectangular cylinder extending axially. The motor frame 32 houses various parts that constitute the electric motor 30, such as the rotor 50, stator 60, bearing holder 70, and circuit board 76. The motor frame 32 has an opening 32a that opens on one side in the axial direction (+X side). Viewed from the axial direction, the opening 32a is substantially circular, centered on the central axis J.

[0031] In this embodiment, the motor frame 32 is made of resin. The material used to construct the motor frame 32 can be a thermoplastic resin such as polybutylene terephthalate (PBT) or polyphenylene sulfide (PPS), or a thermosetting resin such as bulk molding compound (BMC). In this embodiment, the motor frame 32 is formed by insert molding, with the stator 60 and the retaining member 66 each serving as insert members. As a result, at least a portion of the stator 60 and at least a portion of the retaining member 66 are embedded in the motor frame 32. The motor frame 32 has a side wall portion 33, a mounting portion 33g, a bottom wall portion 37, and a second bearing retaining portion 38. As shown in Figure 6, the motor frame 32 has a support portion 34, a fixing portion 35, and a substrate support portion 36.

[0032] As shown in Figure 5, the side wall portion 33 is substantially cylindrical in shape and extends axially with respect to the central axis J. The side wall portion 33 surrounds each part constituting the electric motor 30, such as the rotor 50, the bearing holder portion 70, and the circuit board 76, from the radial outside. The side wall portion 33 has a first side wall portion 33a, a second side wall portion 33c, and a stepped surface 33e.

[0033] The first side wall portion 33a is substantially cylindrical in shape, extending axially with respect to the central axis J. The first side wall portion 33a is the portion of the side wall portion 33 on the other axial side (-X side). The first side wall portion 33a surrounds the rotor 50 from the radial outside. At least a part of the stator 60 and at least a part of the retaining member 66 are embedded inside the first side wall portion 33a. In this embodiment, the entire stator 60 is embedded inside the first side wall portion 33a. The first side wall portion 33a faces the rotor 50 with a radial gap between them.

[0034] The second side wall portion 33c is substantially cylindrical in shape, extending axially with respect to the central axis J. The second side wall portion 33c is the portion of the side wall portion 33 on one axial side (+X side). The other axial end of the second side wall portion 33c (-X side) is connected to the axial end of the first side wall portion 33a. The second side wall portion 33c surrounds the bearing holder portion 70, the bearing 91, and the circuit board 76 from the radially outer side. The outer diameter of the second side wall portion 33c is approximately the same as the outer diameter of the first side wall portion 33a. The inner diameter of the second side wall portion 33c is larger than the inner diameter of the first side wall portion 33a.

[0035] The stepped surface 33e shown in Figure 6 is part of the inner circumferential surface of the side wall portion 33 and is a stepped surface facing one side in the axial direction (+X side). Viewed from the axial direction, the stepped surface 33e is approximately annular with the central axis J as its center. The radially inner end of the stepped surface 33e is connected to one axial end of the inner circumferential surface of the first side wall portion 33a, and the radially outer end of the stepped surface 33e is connected to the other axial end (-X side) of the inner circumferential surface of the second side wall portion 33c.

[0036] The mounting portion 33g is a substantially rectangular parallelepiped that protrudes radially outward from the second side wall portion 33c. The mounting portion 33g is provided with a mounting hole 33h that penetrates the mounting portion 33g in the axial direction. When viewed from the axial direction, the mounting hole 33h is substantially circular in shape. In this embodiment, the motor frame 32 has four mounting portions 33g. The number of mounting portions 33g on the motor frame 32 may be three or fewer, or five or more. Each mounting portion 33g is arranged at substantially equal intervals in the circumferential direction. Although not shown in the figures, when a screw passed through each mounting hole 33h in the axial direction is tightened into a female screw hole provided in the motor holder 27 shown in Figure 3, the motor 30 is fixed to the motor holder 27.

[0037] As shown in Figure 6, the support portion 34 protrudes from the stepped surface 33e to one side in the axial direction (+X side). As shown in Figure 5, the support portion 34 supports the bearing holding portion 70 from the other side in the axial direction (-X side). As shown in Figure 6, the support portion 34 is provided with a first hole portion 34a that penetrates the support portion 34 in the axial direction. Viewed from the axial direction, the first hole portion 34a is substantially circular in shape. In this embodiment, the motor frame 32 has three support portions 34. The number of support portions 34 on the motor frame 32 may be two or fewer, or four or more. Each support portion 34 is provided at substantially equal intervals in the circumferential direction.

[0038] The fixing portion 35 protrudes from the stepped surface 33e to one side in the axial direction. The fixing portion 35 is provided with a second hole 35a that penetrates the fixing portion 35 in the axial direction. When viewed from the axial direction, the second hole 35a is substantially circular in shape. In this embodiment, the motor frame 32 has three fixing portions 35. The number of fixing portions 35 on the motor frame 32 may be two or fewer, or four or more. Each fixing portion 35 is provided at substantially equal intervals in the circumferential direction. Each fixing portion 35 is positioned on the other side (-θ side) in the circumferential direction of different support portions 34 and is connected to the support portion 34 in the circumferential direction.

[0039] Of the three fixing parts 35, the upper (+Z side) and right (-Y side) fixing part 35 has a second support surface 35c on the other side (-θ side) in the circumferential direction, facing one side in the axial direction (+X side). The second support surface 35c is located on the other side (-X side) in the axial direction than the surface of the fixing part 35 facing one side in the axial direction.

[0040] The substrate support portion 36 protrudes from the upper (+Z) and left (+Y) side of the stepped surface 33e to one side in the axial direction (+X). A first support surface 36a facing one side in the axial direction is provided on one side (+θ) of the substrate support portion 36. The first support surface 36a is located on the other side in the axial direction (-X side) of the surface of the substrate support portion 36 facing one side in the axial direction.

[0041] As shown in Figure 5, the bottom wall portion 37 is a substantially annular plate shape centered on the central axis J. The radial outer edge of the bottom wall portion 37 is connected to the other axial end (-X side) of the side wall portion 33. The second bearing holder portion 38 is a substantially cylindrical shape that protrudes in the axial direction. The second bearing holder portion 38 is open on one axial side (+X side). The axial end of the second bearing holder portion 38 on one side is connected to the radial inner edge of the bottom wall portion 37. A bearing 92 is held on the inner circumferential surface of the second bearing holder portion 38. The bearing 92 is a substantially annular shape centered on the central axis J. In this embodiment, the bearing 92 is a rolling bearing. The bearing 92 may also be a sliding bearing. The second bearing holder portion 38 is provided with a hole 38a that penetrates the second bearing holder portion 38 in the axial direction. Viewed from the axial direction, the hole 38a is a substantially circular shape centered on the central axis J.

[0042] The heat dissipation unit 40 is fixed to one end of the motor frame 32 in the axial direction (+X side). The heat dissipation unit 40 closes the opening 32a of the motor frame 32 from one side in the axial direction. The heat dissipation unit 40 includes a heat sink 41, a heat transfer member 46, and an insulating sheet 48.

[0043] As shown in FIG. 4, the heat sink 41 is substantially disc-shaped about the central axis J. As shown in FIG. 5, the heat sink 41 closes the opening 32a from one axial side. In the embodiment, the heat sink 41 is made of metal. As the material constituting the heat sink 41, aluminum, copper, iron, etc. can be used. In the embodiment, the heat sink 41 is made of aluminum. The heat sink 41 has a main body portion 42 and a flange portion 44.

[0044] The main body portion 42 is substantially disc-shaped about the central axis J. The main body portion 42 is the radially inner portion of the heat sink 41. As shown in FIG. 4, a plurality of heat radiation fins 42e are provided on the main body portion 42. As shown in FIG. 5, the main body portion 42 has a main body recess 身凹部42a and a main body clamping surface 42c.

[0045] As shown in FIG. 4, the plurality of heat radiation fins 42e are provided on the surface of the main body portion 42 facing one axial side (+X side). Each heat radiation fin 42e is provided on the upper (+Z side) portion of the main body portion 42. Each heat radiation fin 42e protrudes toward one axial side and is plate-shaped extending in the vertical direction (Z-axis direction). Each heat radiation fin 42e is exposed outside the motor 30. In the embodiment, since the heat sink 41 has a plurality of heat radiation fins 42e, the surface area of the heat sink 41 can be increased. Thereby, the amount of heat radiated from the heat sink 41 to the outside of the motor 30 can be increased.

[0046] As shown in FIG. 5, the main body recess 42a is a depression that depresses from the surface of the main body portion 42 facing the other axial side (-X side) toward one axial side (+X side). The lower (-Z side) end of the main body recess 42a is located slightly above (+Z side) the lower end of the main body portion 42. The upper end of the main body recess 42a is located above the central axis J and below the heat transfer member 46.

[0047] The main body clamping surface 42c is a surface located above the main body recess 42a among the surfaces facing the other axial side of the main body portion 42. The main body clamping surface 42c faces the heat transfer member 46 in the axial direction. The main body clamping surface 42c is in contact with the heat transfer member 46 in the axial direction. Thereby, the heat sink 41 is in contact with the heat transfer member 46 in the axial direction.

[0048] As shown in FIG. 4, the flange portion 44 projects radially outward from the radially outer edge of the main body portion 42. The flange portion 44 has a substantially disc shape centered on the central axis J. The radially outer edge of the flange portion 44 is in contact with the end portion on the one axial side (+X side) of the side wall portion 33 in the axial direction. Three flange holes 44a penetrating the flange portion 44 in the axial direction are provided in the flange portion 44. Each flange hole 44a is provided at substantially equal intervals in the circumferential direction. Although not shown, each flange hole 44a overlaps axially with the different second hole portions 35a shown in FIG. 6.

[0049] As shown in FIG. 5, the space inside the housing 31 includes a first space S1 and a second space S2. The first space S1 is the space on the other axial side (-X side) of the bearing holding portion 70 among the spaces inside the housing 31. The first space S1 is a space surrounded by the first side wall portion 33a, the bottom wall portion 37, the second bearing holding portion 38, and the bearing holding portion 70. The rotor 50 is disposed in the first space S1. The second space S2 is the space on the one axial side (+X side) of the bearing holding portion 70 among the spaces inside the housing 31. The second space S2 is a space surrounded by the second side wall portion 33c, the heat dissipation portion 40, and the bearing holding portion 70. The circuit board 76 is disposed in the second space S2.

[0050] Figure 7 is a second perspective view showing a part of the electric motor 30 in the embodiment. Figure 8 is a partially enlarged cross-sectional view showing a part of the electric motor 30 in the embodiment. As shown in Figure 7, the insulating sheet 48 is a sheet that extends in a direction perpendicular to the axial direction. In the embodiment, the thickness of the insulating sheet 48 is about 500 μm. The insulating sheet 48 is made of resin. The insulating sheet 48 has insulating properties. In the embodiment, the insulating sheet 48 is made of polyethylene terephthalate. The material constituting the insulating sheet 48 may be other resins such as polyester. As shown in Figure 8, in the axial direction, the insulating sheet 48 is placed between the circuit board 76 and the heat sink 41. As a result, the insulating sheet 48 electrically insulates the circuit board 76 and the heat sink 41. As shown in Figure 7, when viewed from the axial direction, the insulating sheet 48 covers the upper (+Z side) portion of the circuit board 76. Furthermore, as shown in Figure 8, the lower (-Z side) end of the insulating sheet 48 is located below the main body clamping surface 42c and, when viewed from the axial direction, overlaps with the main body recess 42a. As a result, even if the axial distance between the circuit board 76 and the heat sink 41 is reduced, the insulating sheet 48 ensures sufficient creepage distance between the circuit board 76 and the heat sink 41. Therefore, since the axial distance between the circuit board 76 and the heat sink 41 can be reduced, the axial enlargement of the electric motor 30 can be suppressed. As shown in Figure 7, the insulating sheet 48 is provided with an opening 48a.

[0051] The opening 48a is a hole that penetrates the insulating sheet 48 in the axial direction. Viewed from the axial direction, the opening 48a is approximately rectangular in shape, with its longer side extending in the left-right direction (Y-axis direction). Viewed from the axial direction, the opening 48a overlaps with the upper (+Z side) portion of the circuit board 76 and the heat transfer member 46.

[0052] As shown in Figure 8, the heat transfer member 46 is sheet-shaped and extends in a direction perpendicular to the axial direction. As shown in Figure 7, in this embodiment, when viewed from the axial direction, the heat transfer member 46 is substantially rectangular in shape, with its longer side extending in the left-right direction (Y-axis direction). When viewed from the axial direction, the heat transfer member 46 may also have other shapes such as circular or triangular. When viewed from the axial direction, the outer edge of the heat transfer member 46 surrounds the opening 48a. When viewed from the axial direction, the heat transfer member 46 overlaps with the upper (+Z side) portion of the circuit board 76. As shown in Figure 8, in the axial direction, the heat transfer member 46 is positioned between the circuit board 76 and the heat sink 41. The heat transfer member 46 is in contact with the upper portion of the circuit board 76 from one side in the axial direction (+X side). The heat transfer member 46 is made of resin. The heat transfer member 46 is insulating. As a result, the heat transfer member 46 electrically insulates the circuit board 76 from the heat sink 41. In this embodiment, the heat transfer member 46 is made of silicone resin. The heat transfer member 46 is flexible. The heat transfer member 46 has a flange portion 46a and a contact portion 46c.

[0053] The flange portion 46a is the part of the heat transfer member 46 that is positioned in the axial direction between the circuit board 76 and the insulating sheet 48. The flange portion 46a is held in the axial direction by the circuit board 76 and the insulating sheet 48. As shown in Figure 7, when viewed from the axial direction, the flange portion 46a is a roughly rectangular annular shape surrounding the opening 48a.

[0054] The contact portion 46c is the part of the heat transfer member 46 that overlaps with the opening 48a when viewed from the axial direction. As described above, the heat transfer member 46 is flexible. Also, as shown in Figure 8, the heat transfer member 46 and the insulating sheet 48 are each held in the axial direction by the circuit board 76 and the main body clamping surface 42c. As a result, when the insulating sheet 48 is pressed against the heat transfer member 46, the flange portion 46a elastically deforms, causing the insulating sheet 48 to move to the other side (-X side) in the axial direction. As a result, the contact portion 46c enters the interior of the opening 48a and comes into axial contact with the main body clamping surface 42c. In other words, the contact portion 46c comes into contact with the heat sink 41. As described above, the heat transfer member 46 is in contact with the circuit board 76. As a result, the heat transfer member 46 comes into contact with the circuit board 76 and the heat sink 41, respectively. Also, as shown in Figure 7, when viewed from the axial direction, the insulating sheet 48 surrounds the contact portion 46c. Although not shown in the diagram, in this embodiment, when viewed from the axial direction, the multiple heat dissipation fins 42e overlap with the contact portion 46c.

[0055] Figure 9 is a third perspective view showing a part of the electric motor 30 in the embodiment. Figure 10 is a fourth perspective view showing a part of the electric motor 30 in the embodiment. As shown in Figure 5, the bearing holder 70 is located inside the second side wall 33c. The bearing holder 70 is located on one axial side (+X side) of the rotor 50 and stator 60. The bearing holder 70 is located on the other axial side (-X side) of the circuit board 76. In the embodiment, the bearing holder 70 is made of resin. Thermoplastic resins such as PBT, PPS, and BMC can be used as the material for the bearing holder 70. As shown in Figure 9, the bearing holder 70 has a holding body 71 and a plurality of leg portions 74.

[0056] As shown in Figure 5, the retaining body portion 71 is substantially disc-shaped, extending in a direction perpendicular to the axial direction. The retaining body portion 71 is substantially disc-shaped with respect to the central axis J. The retaining body portion 71 is provided with a recess 71a. Furthermore, as shown in Figure 9, the retaining body portion 71 has a plurality of body protrusions 71c and a plurality of projections 72. That is, the bearing retaining portion 70 has a plurality of projections 72.

[0057] As shown in Figure 5, the recess 71a is a recess that extends from the other axial side (-X side) of the retaining body portion 71 toward one axial side (+X side). Viewed from the axial direction, the recess 71a is substantially circular in shape with the central axis J at its center. The bearing 91 is held on the inner circumferential surface of the recess 71a. Thus, the bearing retaining portion 70 holds the bearing 91. The bearing 91 is substantially annular in shape with the central axis J at its center. In this embodiment, the bearing 91 is a rolling bearing. The bearing 91 may also be a sliding bearing.

[0058] As shown in Figure 9, each of the multiple main body protrusions 71c is a projection that extends radially outward from the holding main body 71. Viewed from the axial direction, each main body protrusion 71c is approximately semicircular in shape. Each main body protrusion 71c is arranged at approximately equal intervals in the circumferential direction.

[0059] Each of the multiple projections 72 is a projection that protrudes from the retaining body 71 to one side in the axial direction (+X side). When viewed from the axial direction, each projection 72 is substantially circular in shape. In this embodiment, the bearing retaining part 70 has six projections 72. The number of projections 72 on the bearing retaining part 70 may be five or fewer, or seven or more. The multiple projections 72 include three first projections 72a and three second projections 72c.

[0060] Each first projection 72a protrudes from the holding body portion 71 to one side in the axial direction (+X side). Each first projection 72a is spaced apart from each other in the circumferential direction. In this embodiment, each first projection 72a is spaced equally apart from each other in the circumferential direction. Each second projection 72c protrudes from different body projections 71c to one side in the axial direction. Each second projection 72c is spaced apart from each other in the circumferential direction. In this embodiment, each second projection 72c is spaced equally apart from each other in the circumferential direction. As shown in Figure 10, when viewed from the axial direction, each projection 72 overlaps with the circuit board 76 in the axial direction. Each projection 72 supports the circuit board 76 from the other side in the axial direction (-X side) in the axial direction.

[0061] As shown in Figure 9, each of the multiple leg portions 74 is plate-shaped and protrudes radially outward from the holding body portion 71. The plate surface of each leg portion 74 is oriented in the axial direction. In this embodiment, the bearing holding portion 70 has three leg portions 74. The number of leg portions 74 in the bearing holding portion 70 may be two or four or more. Each leg portion 74 is spaced apart from each other in the circumferential direction. In this embodiment, each leg portion 74 is spaced equally apart from each other in the circumferential direction. As shown in Figures 5 and 9, the first space S1 and the second space S2 are connected in the axial direction via the spaces between the leg portions 74. As shown in Figure 10, in this embodiment, when viewed from the axial direction, the upper (+Z side) portion of the circuit board 76 overlaps with the space between a pair of leg portions 74. That is, when viewed from the axial direction, a part of the circuit board 76 overlaps with the space between the leg portions 74.

[0062] As shown in Figure 5, the leg portion 74 is provided with through holes 74a. The through holes 74a are holes that penetrate the leg portion 74 in the axial direction. Although not shown in the figure, when viewed from the axial direction, each through hole 74a overlaps with a first hole portion 34a provided in different support portions 34.

[0063] Figure 11 is a perspective view showing the rotor 50 in an embodiment. As shown in Figure 5, the rotor 50 is located inside the motor frame 32. More specifically, the rotor 50 is located inside the first side wall portion 33a. The rotor 50 is substantially annular in shape with respect to the central axis J. The rotor 50 is rotatable about the central axis J. The rotor 50 includes a rotor core 51, a plurality of magnets 52, and a connecting portion 55.

[0064] The rotor core 51 is annular in shape with respect to the central axis J. In this embodiment, the rotor core 51 is substantially annular in shape with respect to the central axis J. The rotor core 51 surrounds the shaft 53 from the radial outside. Each of the multiple magnets 52 is housed inside the rotor core 51. The magnets 52 are spaced apart in the circumferential direction. Although not shown in the figures, in this embodiment, the rotor 50 has 10 magnets 52. The number of magnets 52 in the rotor 50 may be 9 or less, or 11 or more.

[0065] The shaft 53 is substantially cylindrical and extends along the central axis J. The shaft 53 passes axially through the inside of the rotor core 51 and through the hole 38a of the second bearing holder 38. One axial side (+X side) of the shaft 53 is located inside the housing 31. The axial end of the shaft 53 is rotatably supported about the central axis J by a bearing 91. Thus, the bearing 91 rotatably supports the portion of the shaft 53 that is axially ahead of the rotor 50. The axial central portion of the shaft 53 is rotatably supported about the central axis J by a bearing 92. As a result, the shaft 53 is rotatable about the central axis J. The other axial side (-X side) of the shaft 53 protrudes forward of the motor frame 32, i.e., to the other axial side, through the hole 38a. As a result, as shown in Figure 3, the other axial portion of the shaft 53 passes through the inside of the cylindrical portion 15a in the front-to-back direction (X-axis direction) and is fixed to the cylindrical portion 15a. Therefore, when the shaft 53 rotates about the central axis J, each rotor blade 15b rotates as described above, and an airflow A is formed that flows from the rear side (+X side) to the front side (+X side).

[0066] As shown in Figure 11, the connecting portion 55 is substantially annular in shape with respect to the central axis J. The connecting portion 55 connects the shaft 53 and the rotor core 51. As a result, when the rotor 50 rotates about the central axis J, the shaft 53 rotates together with the rotor 50 about the central axis J. In this embodiment, the connecting portion 55 is made of resin. In this embodiment, the connecting portion 55 is formed by insert molding, with the rotor core 51 containing a plurality of magnets 52 and the shaft 53 each serving as insert members. The connecting portion 55 has an inner ring portion 56a, an outer ring portion 56c, a plurality of ribs 57, cover portions 58a, 58c, and a plurality of protrusions 58e.

[0067] As shown in Figure 5, the inner ring portion 56a is an annular shape that surrounds the shaft 53 from the radially outer side. In this embodiment, the inner ring portion 56a is substantially annular with respect to the central axis J. The inner ring portion 56a is fixed to the radially outward-facing surface of the shaft 53. The outer ring portion 56c is an annular shape that surrounds the inner ring portion 56a from the radially outer side. In this embodiment, the outer ring portion 56c is substantially annular with respect to the central axis J. The outer ring portion 56c faces the inner ring portion 56a with a radial gap between them. The outer ring portion 56c is fixed to the radially inward-facing surface of the rotor core 51.

[0068] As shown in Figure 11, the multiple ribs 57 are arranged between the inner ring portion 56a and the outer ring portion 56c. Each rib 57 is plate-shaped and extends radially. Each rib 57 is spaced apart from each other in the circumferential direction. The radial inner end of each rib 57 is connected to the inner ring portion 56a. The radial outer end of each rib 57 is connected to the outer ring portion 56c. In this way, each rib 57 connects the inner ring portion 56a and the outer ring portion 56c. In this embodiment, each rib 57 is inclined circumferentially with respect to the axial direction. Each rib 57 may extend axially. In this embodiment, each rib 57 is located on one side of the circumferential direction (+θ side) as it moves toward the other side of the axial direction (-X side). Each rib 57 may be located on the other side of the circumferential direction (-θ side) as it moves toward the other side of the axial direction.

[0069] The cover portion 58a is substantially disc-shaped with respect to the central axis J. The plate surface of the cover portion 58a faces axially. The radially inner end of the cover portion 58a is connected to one axial end (+X side) of the outer ring portion 56c. The cover portion 58a is fixed to the surface of the rotor core 51 facing one axial side. The cover portion 58a covers at least a portion of the surface of the rotor core 51 facing one axial side. In this embodiment, the cover portion 58a covers the entire surface of the rotor core 51 facing one axial side. The cover portion 58a does not have to cover the entire surface of the rotor core 51 facing one axial side.

[0070] As shown in Figure 5, the cover portion 58c is substantially disc-shaped with the central axis J at its center. The plate surface of the cover portion 58a faces axially. The radially inner end of the cover portion 58a is connected to the other axial end (-X side) of the outer ring portion 56c. The cover portion 58a is fixed to the surface of the rotor core 51 facing the other axial side.

[0071] As shown in Figure 11, the multiple protrusions 58e are projections that extend from the cover portion 58a to one side in the axial direction (+X side). Viewed from the axial direction, each protrusion 58e is substantially rectangular in shape, with its longer side extending in the radial direction. In this embodiment, the connecting portion 55 has five protrusions 58e. The number of protrusions 58e on the connecting portion 55 may be four or fewer, or six or more. Note that the connecting portion 55 does not necessarily have multiple protrusions 58e.

[0072] The airflow AF shown in Figure 5 represents the airflow that flows from the first space S1 to the second space S2 through the space between the legs 74 as the rotor 50 rotates around the central axis J. When the rotor 50 rotates around the central axis J, the air in the first space S1 is agitated by the rotor 50. As a result, the airflow AF that flows from the first space S1 to the second space S2 through the space between the legs 74 is formed.

[0073] As the rotor 50 rotates about the central axis J, the connecting portion 55 rotates together with the rotor 50 about the central axis J. Therefore, in this embodiment, as the rotor 50 rotates about the central axis J, the air in the first space S1 can be agitated by each rib 57. This makes it possible to more effectively enhance the agitation capacity of the air in the first space S1 due to the rotation of the rotor 50. Consequently, the flow velocity of the air flowing from the first space S1 to the second space S2 can be increased.

[0074] Furthermore, as described above, in the embodiment, each rib 57 is inclined in the circumferential direction with respect to the axial direction. Therefore, when the rotor 50 rotates about the central axis J, the flow velocity of the air flowing in the axial direction can be suitably increased by each rib 57. This makes it possible to suitably increase the flow velocity of the air flowing from the first space S1 to the second space S2.

[0075] Furthermore, as described above, in this embodiment, the connecting portion 55 has a plurality of protrusions 58e. Therefore, when the rotor 50 rotates about the central axis J, the air in the first space S1 can be agitated by each protrusion 58e. This allows for a more favorable increase in the agitation capacity of the air in the first space S1 due to the rotation of the rotor 50, and thus allows for a more favorable increase in the flow velocity of the air flowing from the first space S1 to the second space S2.

[0076] As shown in Figure 5, the stator 60 is substantially annular in shape with a central axis J. The stator 60 is positioned radially outward from the rotor 50. The stator 60 faces the rotor 50 with a radial gap between them. As described above, at least a portion of the stator 60 is embedded inside the first side wall portion 33a. This allows the stator 60 to be held by the motor frame 32. In this embodiment, the entire stator 60 is embedded inside the first side wall portion 33a. The stator 60 has a stator core 61, an insulator 62, and a plurality of coil portions 63.

[0077] The stator core 61 is substantially annular in shape with a central axis J at its center. The stator core 61 surrounds the rotor 50 from the radially outer side. The stator core 61 has a core back portion 61a and a tooth portion 61c. The core back portion 61a is substantially annular in shape with a central axis J at its center. The tooth portion 61c protrudes radially inward from the radially inward-facing surface of the core back portion 61a. In this embodiment, the stator core 61 has a plurality of tooth portions 61c. Each tooth portion 61c is spaced apart from each other in the circumferential direction. The insulator 62 insulates the stator core 61 from the plurality of coil portions 63. In this embodiment, the insulator 62 is made of resin. The insulator 62 has insulating properties. In this embodiment, the stator 60 has a plurality of insulators 62. Each insulator 62 is mounted on a different tooth portion 61c from each other.

[0078] Each of the multiple coil sections 63 is mounted on a different tooth section 61c via an insulator 62. Each coil section 63 is composed of a coil wound around the outer circumferential surface of the tooth section 61c. The coil sections 63 are spaced apart from each other in the circumferential direction. In this embodiment, the multiple coil sections 63 include multiple U-phase coils, multiple V-phase coils, and multiple W-phase coils. Each U-phase coil, each V-phase coil, and each W-phase coil is supplied with an alternating current from the circuit board 76, with an electrical angle difference of 120° from each other. When current is supplied to each coil section 63, each coil section 63 constitutes an electromagnet with its magnetic poles facing radially. When each coil section 63 constitutes an electromagnet, an electromagnetic force is applied to each magnet 52 of the rotor 50. When alternating currents with electrical angles shifted by 120° from each other are supplied from the circuit board 76 to each U-phase coil, each V-phase coil, and each W-phase coil, an electromagnetic force is applied to each magnet 52 of the rotor 50 in the circumferential direction, causing the rotor 50 to rotate about its central axis J. As a result, the shaft 53 rotates together with the rotor 50 about its central axis J.

[0079] Figure 12 is a perspective view showing the retaining member 66 in the embodiment. As shown in Figure 12, the retaining member 66 is substantially annular in shape with a central axis J. As shown in Figure 5, the retaining member 66 holds the conductive member 81. At least a portion of the retaining member 66 is embedded inside the first side wall portion 33a, each support portion 34, and each fixing portion 35. As a result, the retaining member 66 is held by the motor frame 32. In the embodiment, the retaining member 66 is made of resin. For example, PBT can be used as the material for the retaining member 66. As shown in Figure 12, the retaining member 66 has an annular retaining portion 67, a first protrusion 68, and a second protrusion 69. The retaining member 66 is provided with a plurality of insertion holes 67b.

[0080] The annular holding portion 67 is a substantially circular plate shape centered on the central axis J. The plate surface of the annular holding portion 67 is oriented in the axial direction. As shown in Figure 5, the annular holding portion 67 is embedded inside the first side wall portion 33a. As shown in Figure 12, the annular holding portion 67 is provided with a plurality of protrusions 67a and a plurality of claw portions 67d.

[0081] Each protrusion 67a projects from the upper (+Z) portion of the surface of the annular holding portion 67 facing one side in the axial direction (+X side) to one side in the axial direction. In this embodiment, the annular holding portion 67 is provided with three protrusions 67a. Each protrusion 67a is spaced apart in the circumferential direction. As shown in Figure 6, the upper end of each protrusion 67a projects from the first side wall portion 33a to one side in the axial direction.

[0082] As shown in Figure 12, each claw portion 67d is plate-shaped and protrudes from the radial outer edge of the annular retaining portion 67 to the other axial side (-X side). The plate surface of each claw portion 67d faces radially. Each claw portion 67d is provided at approximately equal intervals in the circumferential direction. Although not shown in the figure, the tip of each claw portion is located inside a recess provided on the radially outward-facing surface of the stator core 61. In this way, the retaining member 66 is attached to the stator 60.

[0083] As shown in Figure 5, the multiple through holes 67b are holes that penetrate the annular holding portion 67 and the different protrusions 67a in the axial direction. As shown in Figure 6, in this embodiment, the holding member 66 is provided with three through holes 67b. A conductive member 81 is passed through each of the through holes 67b in the axial direction.

[0084] Each conductive member 81 is made of metal. Each conductive member 81 is electrically conductive. As shown in Figure 10, one end of each conductive member 81 in the axial direction (+X side) is fixed to the circuit board 76 by solder (not shown). This electrically connects each conductive member 81 to the circuit board 76. As shown in Figure 5, different lead wires 63a drawn from the U-phase coil, V-phase coil, and W-phase coil are connected to the other end of each conductive member 81 in the axial direction (-X side). This electrically connects the circuit board 76 to the multiple coil sections 63 via each conductive member 81.

[0085] As shown in Figure 12, the first projection 68 is substantially cylindrical in shape and protrudes from the annular holding portion 67 to one side in the axial direction (+X side). The first projection 68 is provided with a first female screw hole 68a that is recessed from the surface of the first projection 68 facing one side in the axial direction to the other side in the axial direction (-X side). In this embodiment, the holding member 66 has three first projections 68. Each first projection 68 is provided at substantially equal intervals in the circumferential direction. As shown in Figure 5, each first projection 68 is embedded inside different support portions 34 of the motor frame 32. Although not shown, when viewed from the axial direction, each first female screw hole 68a overlaps with each of the different first holes 34a and different through holes 74a. When the screw 93 is passed through the through hole 74a and the first hole 34a respectively and tightened into each of the first female screw holes 68a, the bearing holder 70 is fixed to the motor frame 32, as shown in Figure 7.

[0086] As shown in Figure 12, the second projection 69 is substantially cylindrical in shape and protrudes from the annular holding portion 67 to one side in the axial direction (+X side). The second projection 69 is provided with a second female screw hole 69a that is recessed from the surface of the second projection 69 facing one side in the axial direction to the other side in the axial direction (-X side). In this embodiment, the holding member 66 has three second projections 69. Each second projection 69 is provided at substantially equal intervals in the circumferential direction. Although not shown, each first projection 68 is embedded inside different fixing portions 35 of the motor frame 32 shown in Figure 6. Although not shown, when viewed from the axial direction, each second female screw hole 69a overlaps with different flange holes 44a and different second holes 35a, respectively. When the screw 94 shown in Figure 4 is passed axially through the flange hole 44a and the second hole 35a, respectively, and tightened into the second female screw holes 69a, the heat sink 41 is fixed to the motor frame 32. In other words, the heat dissipation section 40 is fixed to the motor frame 32.

[0087] Figure 13 is a cross-sectional view of the electric motor 30 in the embodiment, and is a cross-sectional view taken along line XIII-XIII in Figure 5. As shown in Figure 5, the circuit board 76 is plate-shaped and extends in a direction perpendicular to the axial direction. As described above, the circuit board 76 is electrically connected to a plurality of coil sections 63 and supplies current to the plurality of coil sections 63. That is, the circuit board 76 supplies current to the stator 60. As described above, the circuit board 76 is located in the second space S2 of the housing 31. As shown in Figure 10, when viewed from the axial direction, the circuit board 76 is substantially rectangular in shape with its long side extending in the vertical direction (Z-axis direction). As shown in Figure 5, the circuit board 76 is located on one side (+X side) of the bearing holder 70 in the axial direction. The circuit board 76 is located between the bearing holder 70 and the heat dissipation section 40 in the axial direction. As described above, the plurality of protrusions 72 of the bearing holder 70 support the circuit board 76 in the axial direction from the other side (-X side). Furthermore, as described above, the heat transfer member 46 of the heat dissipation section 40 is in contact with the upper (+Z side) portion of the circuit board 76 from one side in the axial direction. As a result, the circuit board 76 is held between the multiple protrusions 72 and the heat dissipation section 40. In other words, the circuit board 76 is held between the bearing holding section 70 and the heat dissipation section 40. This ensures stable contact between the circuit board 76 and the heat dissipation section 40, thereby increasing the amount of heat transferred from the circuit board 76 to the heat dissipation section 40.

[0088] Multiple electronic components 77 are mounted on the circuit board 76. The multiple electronic components 77 include multiple first electronic components 77a, multiple second electronic components 77c, and multiple third electronic components 77e. As shown in Figure 8, the multiple first electronic components 77a are mounted on the upper (+Z) portion of the surface of the circuit board 76 facing the other side in the axial direction (-X side). As shown in Figure 13, on the surface of the circuit board 76 facing the other side in the axial direction, multiple first electronic components 77a, i.e., multiple electronic components 77, are mounted in the portion that overlaps with the space between the leg portions 74 when viewed from the axial direction. The multiple first electronic components 77a, i.e., multiple electronic components 77, include at least one switching element 77b, a capacitor, and a resistor, etc. Although not shown in the illustration, in this embodiment, the multiple first electronic components 77a include six switching elements 77b. In this embodiment, the switching elements are, for example, power semiconductor elements such as insulated-gate bipolar transistors (IGBTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs). Each switching element 77b generates alternating current supplied to the stator 60 from the direct current supplied to the circuit board 76. When the motor 30 is operating, the amount of heat generated by the switching elements 77b is greater than the amount of heat generated by other electronic components. Therefore, in order to suppress the temperature rise of the circuit board 76, it is necessary to increase the amount of heat dissipated from the switching elements 77b to the outside of the motor 30.

[0089] As shown in Figure 5, the multiple second electronic components 77c are mounted on the lower (-Z) portion of the other side (-X) in the axial direction of the circuit board 76. The multiple second electronic components 77c include capacitors and resistors, etc. As shown in Figure 10, the multiple third electronic components 77e are mounted on the one side (+X) in the axial direction of the circuit board 76. The multiple third electronic components 77e include capacitors and resistors, etc. Each of the multiple second electronic components 77c and the multiple third electronic components 77e may include a switching element 77b.

[0090] In Figure 8, the arrow HF indicates the flow of heat dissipated from the circuit board 76 to the outside of the motor 30. As described above, since the circuit board 76 is held between the bearing holding portion 70 and the heat dissipation portion 40, stable contact can be maintained between the circuit board 76 and the heat dissipation portion 40. This reduces the thermal resistance between the circuit board 76 and the heat dissipation portion 40, thereby increasing the amount of heat transferred from the circuit board 76 to the heat dissipation portion 40. Consequently, the amount of heat dissipated from the circuit board 76 to the outside of the motor 30 via the heat dissipation portion 40 can be increased.

[0091] As shown in Figure 5, when the rotor 50 rotates about the central axis J, as described above, air flows from the first space S1 to the second space S2 through the spaces between the legs 74 of the bearing holder 70, and the air that flows into the second space S2 flows along the circuit board 76. Therefore, the air flowing through the second space S2 easily comes into contact with the circuit board 76. This increases the amount of heat dissipated from the circuit board 76 to the air flowing through the second space S2. Also, as described above, on the other side (-X side) of the axial direction of the circuit board 76, a plurality of first electronic components 77a, including at least one switching element 77b, are mounted on the portion that overlaps with the spaces between the legs 74 when viewed from the axial direction. Therefore, the air flowing through the second space S2 easily comes into contact with the switching element 77b. This increases the amount of heat dissipated from the switching element 77b to the air flowing through the second space S2. The air flowing through the second space S2 flows along the circuit board 76 and then comes into contact with the heat sink 41. This increases the amount of heat transferred from the circuit board 76 and switching element 77b to the heat sink 41 via the air flowing through the second space S2. Consequently, the amount of heat dissipated from the circuit board 76 and switching element 77b to the outside of the electric motor 30 can be increased.

[0092] According to this embodiment, the electric motor 30 includes a rotor 50 rotatable about a central axis J, a shaft 53 extending axially along the central axis J and rotatable together with the rotor 50 about the central axis J, a stator 60 positioned radially outside the rotor 50 and facing the rotor 50 at a radial distance, a bearing 91 rotatably supporting the portion of the shaft 53 on one axial side (+X side) of the rotor 50, a bearing holder 70 holding the bearing 91, a circuit board 76 positioned on one axial side of the bearing holder 70, and a housing 31 that houses the rotor 50, stator 60, bearing holder 70, and circuit board 76 inside. The housing 31 is cylindrical, extending axially around a central axis J, and includes a motor frame 32 having an opening 32a on one side in the axial direction, and a heat dissipation section 40 that closes the opening 32a. At least a portion of the stator 60 is embedded in the motor frame 32, and the circuit board 76 is held between the bearing holding section 70 and the heat dissipation section 40. Therefore, as described above, the circuit board 76 and the heat dissipation section 40 are in stable contact, which reduces the thermal resistance between the circuit board 76 and the heat dissipation section 40. This increases the amount of heat transferred from the circuit board 76 to the heat dissipation section 40. As a result, the amount of heat dissipated from the circuit board 76 to the outside of the motor 30 via the heat dissipation section 40 can be increased. Consequently, it is possible to prevent the temperature of the circuit board 76 from becoming too high.

[0093] According to this embodiment, the heat dissipation section 40 includes a metal heat sink 41 that closes the opening 32a, and a resin heat transfer member 46 that is positioned axially between the circuit board 76 and the heat sink 41 and contacts both the circuit board 76 and the heat sink 41. Therefore, the thermal conductivity of the heat sink 41 can be increased compared to the case where the heat sink 41 is made of resin. This increases the amount of heat dissipated from the circuit board 76 to the outside of the electric motor 30 via the heat sink 41. Consequently, it is possible to prevent the temperature of the circuit board 76 from becoming too high.

[0094] Furthermore, in this embodiment, the circuit board 76 and the conductive heat sink 41 can be brought into contact via an insulating heat transfer member 46. This allows the heat transfer member 46 to electrically insulate the circuit board 76 and the heat sink 41. Therefore, short circuits between the circuit board 76 and the heat sink 41 can be suppressed.

[0095] Furthermore, in this embodiment, the heat transfer member 46 is made of flexible silicone resin. This improves the adhesion between the heat transfer member 46 and the circuit board 76 and the heat sink 41. As a result, the thermal resistance between the circuit board 76 and the heat transfer member 46, and the thermal resistance between the heat transfer member 46 and the heat sink 41 can be reduced. Therefore, since the thermal resistance between the circuit board 76 and the heat sink 41 can be reduced, the amount of heat transferred from the circuit board 76 to the heat sink 41 can be more effectively increased. Thus, the temperature of the circuit board 76 can be more effectively prevented from becoming too high.

[0096] According to this embodiment, a plurality of heat dissipation fins 42e are provided on the surface of the heat sink 41 facing one side in the axial direction (+X side). Therefore, as described above, the surface area of ​​the surface of the heat sink 41 facing one side in the axial direction can be increased by the plurality of heat dissipation fins 42e. This makes it possible to more effectively increase the amount of heat dissipated from the circuit board 76 to the outside of the electric motor 30 via the heat sink 41. Consequently, it is possible to more effectively suppress the temperature of the circuit board 76 from becoming too high.

[0097] According to this embodiment, the heat dissipation section 40 extends in a direction perpendicular to the axial direction and has an insulating sheet 48 that electrically insulates the circuit board 76 and the heat sink 41. The heat transfer member 46 has a contact portion 46c that contacts the heat sink, and when viewed from the axial direction, the insulating sheet 48 surrounds the contact portion 46c. Therefore, since the insulating sheet 48 electrically insulates the circuit board 76 and the heat sink 41, short circuits between the circuit board 76 and the heat sink 41 can be more effectively suppressed.

[0098] According to this embodiment, when viewed from the axial direction, the multiple heat dissipation fins 42e overlap with the contact portion 46c. Therefore, the distance between each heat dissipation fin 42e and the contact portion 46c can be easily shortened, making it easier to reduce the thermal resistance between each heat dissipation fin 42e and the contact portion 46c. This allows for a more favorable increase in the amount of heat dissipated from the circuit board 76 to the outside of the motor 30 via the heat transfer member 46 and the heat sink 41. Consequently, it is possible to more favorably suppress the temperature of the circuit board 76 from becoming too high.

[0099] According to this embodiment, the bearing holder 70 has a plurality of protrusions 72 projecting to one side in the axial direction (+X side), and the circuit board 76 is held between the plurality of protrusions 72 and the heat dissipation portion 40. Therefore, the circuit board 76 can be supported from the other side in the axial direction (-X side) by the plurality of protrusions 72, which have a small area when viewed from the axial direction, making it easier to suppress contact between each protrusion 72 and the plurality of electronic components 77 mounted on the circuit board 76. This makes it possible to suppress stress on the electronic components 77. Furthermore, since the circuit board 76 can be stably supported by each protrusion 72, the circuit board 76 and the heat dissipation portion 40 can be made to contact more stably. This makes it possible to increase the amount of heat dissipated from the circuit board 76 to the outside of the motor 30 via the heat dissipation portion 40. Therefore, it is possible to suppress the temperature of the circuit board 76 from becoming too high while suppressing damage to the electronic components 77.

[0100] According to the embodiment, the bearing holder 70 has a holding body portion 71 that extends in a direction perpendicular to the axial direction, and a plurality of legs 74 that protrude radially outward from the holding body portion 71. The plurality of legs 74 are spaced apart from each other in the circumferential direction, and when viewed from the axial direction, a part of the circuit board 76 overlaps with the space between the legs 74. Therefore, when the rotor 50 rotates about the central axis J, the air flowing from the first space S1 to the second space S2 through the space between the legs 74 can be suitably brought into contact with the circuit board 76. This increases the amount of heat transferred from the circuit board 76 to the air flowing through the second space S2. Also, as described above, the air flowing through the second space S2 flows along the circuit board 76 and then comes into contact with the heat sink 41. Therefore, the amount of heat transferred from the circuit board 76 to the heat sink 41 via the air flowing through the second space S2 can be increased. Therefore, the amount of heat dissipated from the circuit board 76 to the outside of the electric motor 30 can be more effectively increased, thus more effectively preventing the temperature of the circuit board 76 from becoming too high.

[0101] According to this embodiment, on the other side (-X side) of the circuit board 76 facing axially, a plurality of first electronic components 77a, i.e., a plurality of electronic components 77, are mounted in the portion that overlaps with the space between the leg portions 74 when viewed from the axial direction. Therefore, when the rotor 50 rotates about the central axis J, the air flowing from the first space S1 to the second space S2 through the space between the leg portions 74 can be suitably brought into contact with each of the plurality of first electronic components 77a. This allows the amount of heat transferred from the plurality of first electronic components 77a to the heat sink 41 via the air flowing through the second space S2 to be suitably increased. Consequently, the amount of heat dissipated from the plurality of first electronic components 77a to the outside of the motor 30 can be suitably increased, thus suitably preventing the temperature of the plurality of first electronic components 77a from becoming too high.

[0102] In this embodiment, each of the multiple first electronic components 77a, i.e., multiple electronic components 77, includes at least one switching element 77b. As described above, the heat generated by the switching element 77b is greater than that generated by the other electronic components. Therefore, the temperature of the switching element 77b tends to rise. In contrast, in this embodiment, when the rotor 50 rotates about the central axis J, the air flowing from the first space S1 to the second space S2 through the space between the legs 74 can be suitably brought into contact with the switching element 77b. This allows the amount of heat transferred from the switching element 77b to the heat sink 41 via the air flowing through the second space S2 to be suitably increased. Therefore, the amount of heat dissipated from the switching element 77b to the outside of the motor 30 can be suitably increased, thus suitably preventing the temperature of the switching element 77b from becoming too high. This further suitsably prevents the temperature of the circuit board 76 from becoming too high.

[0103] According to the embodiment, the rotor 50 has an annular rotor core 51 that surrounds the shaft 53 from the radially outer side, and a connecting portion 55 that connects the shaft 53 and the rotor core 51. The connecting portion 55 has an annular inner ring portion 56a fixed to the radially outward-facing surface of the shaft 53, an annular outer ring portion 56c fixed to the radially inward-facing surface of the rotor core 51, and a plurality of ribs 57 connecting the inner ring portion 56a and the outer ring portion 56c. The plurality of ribs 57 are arranged at intervals from each other in the circumferential direction. Therefore, as described above, when the rotor 50 rotates about the central axis J, the air in the first space S1 can be stirred by each rib 57. As a result, as described above, the flow velocity of the air flowing from the first space S1 to the second space S2 can be increased. Therefore, the amount of heat transferred from the circuit board 76 to the air flowing through the second space S2 can be more effectively increased. Therefore, the amount of heat dissipated from the circuit board 76 to the outside of the electric motor 30 can be more effectively increased, thus more effectively preventing the temperature of the circuit board 76 from becoming too high.

[0104] According to this embodiment, each of the multiple ribs 57 is inclined circumferentially with respect to the axial direction. Therefore, as described above, when the rotor 50 rotates about the central axis J, the velocity of the air flowing axially can be more effectively increased by each rib 57. This allows for a more effectively increased velocity of the air flowing from the first space S1 to the second space S2. Consequently, the amount of heat transferred from the circuit board 76 to the air flowing through the second space S2 can be more effectively increased. Therefore, the amount of heat dissipated from the circuit board 76 to the outside of the motor 30 can be more effectively increased, thus preventing the temperature of the circuit board 76 from becoming too high.

[0105] According to the embodiment, the connection portion 55 has a cover portion 58a that covers at least a part of the surface of the rotor core 51 facing one side in the axial direction (+X side), and a plurality of protrusions 58e that protrude from the cover portion 58a to one side in the axial direction. Therefore, as described above, when the rotor 50 rotates about the central axis J, the air in the first space S1 can be stirred by each protrusion 58e. As a result, as described above, the flow velocity of the air flowing from the first space S1 to the second space S2 can be more favorably increased. Therefore, the amount of heat transferred from the circuit board 76 to the air flowing through the second space S2 can be more favorably increased. Consequently, the amount of heat dissipated from the circuit board 76 to the outside of the electric motor 30 can be more favorably increased, and the temperature of the circuit board 76 can be more favorably prevented from becoming too high.

[0106] According to this embodiment, the outdoor unit 10 includes an electric motor 30, a blower fan 15 rotated by the electric motor 30, and a heat exchanger 13 through which the airflow A generated by the blower fan 15 passes. As described above, the circuit board 76 of the electric motor 30 is held by a bearing holding portion 70 and a heat dissipation portion 40. Therefore, as described above, the circuit board 76 and the heat dissipation portion 40 are in stable contact, which increases the amount of heat dissipated from the circuit board 76 to the outside of the electric motor 30 via the heat dissipation portion 40. Consequently, it is possible to prevent the temperature of the circuit board 76 from becoming too high.

[0107] While embodiments of this disclosure have been described above, this disclosure is not limited to the configurations of the embodiments described above, and the following configurations and methods may also be adopted.

[0108] The bearing retainer may be a disc shape having only a retaining body and no multiple legs. In this configuration, the outer diameter of the retaining body is larger than that of the retaining body in the above-described embodiment, and through holes are provided in the retaining body, and the retaining body is fixed to the motor frame by screws. Therefore, in this configuration, the first space and the second space are separated from each other by the bearing retainer. However, as described above, since the connecting part has multiple ribs and multiple protrusions, even in this configuration, the air agitation capacity of the first space can be suitably increased. As a result, the temperature rise in the first space can be suppressed, and therefore the temperature rise in the second space can be suppressed. Consequently, it is possible to prevent the temperature of the circuit board from becoming too high. Furthermore, in this configuration, the rigidity of the bearing retainer can be increased compared to the above-described embodiment. Therefore, vibrations transmitted from the rotor and shaft to the housing via the bearing and bearing retainer can be suitably suppressed. Consequently, vibrations of the electric motor can be suitably suppressed. In this context, the configuration in which the first space and the second space are separated by the bearing holder means a configuration in which air is less likely to flow between the first space and the second space, and a small gap may exist between the outer circumference of the disc-shaped bearing holder and the inner circumference of the motor frame.

[0109] The object driven by the electric motor is not limited to the blower fan of the outdoor unit; for example, it may also be the blower fan of the indoor unit.

[0110] The configuration of the heat dissipation section is not limited to this embodiment; for example, the multiple heat dissipation fins, when viewed from the axial direction, do not need to overlap with the contact area. Also, the heat sink does not need to have heat dissipation fins. Furthermore, the heat dissipation section does not need to have an insulating sheet.

[0111] The configurations and methods described herein can be combined as appropriate, provided they are not contradictory.

[0112] 10...Outdoor unit, 13...Heat exchanger, 15...Blower fan, 30...Electric motor, 31...Housing, 32...Motor frame, 32a...Opening, 40...Heat dissipation section, 41...Heat sink, 42e...Heat dissipation fins, 46...Heat transfer element, 46c...Contact section, 48...Insulating sheet, 50...Rotor, 51...Rotor core, 53...Shaft, 55...Connection section, 56a...Inner ring section, 56c...Outer ring section, 57...Rib, 58a...Cover section, 58e...Protruding section, 60...Stator, 70...Bearing holder section, 71...Holding body section, 72...Protrusion, 74...Leg section, 76...Circuit board, 77a...First electronic component (electronic component), 77b...Switching element, 91...Bearing, J...Central axis

Claims

1. An electric motor comprising: a rotor rotatable about a central axis extending in the axial direction; a shaft extending in the axial direction along the central axis and rotatable together with the rotor about the central axis; a stator positioned radially outside the rotor with respect to the central axis and facing the rotor at a radial distance; a bearing rotatably supporting a portion of the shaft on one side in the axial direction relative to the rotor; a bearing holder for holding the bearing; a circuit board positioned on one side in the axial direction relative to the bearing holder; and a housing that houses the rotor, the stator, the bearing holder, and the circuit board inside, wherein the housing comprises: a motor frame that is cylindrical, surrounding the central axis and extending in the axial direction, and having an opening on one side in the axial direction; and a heat dissipation portion that closes the opening; at least a portion of the stator is embedded in the motor frame; and the circuit board is held between the bearing holder and the heat dissipation portion.

2. The electric motor according to claim 1, wherein the heat dissipation section comprises a metal heat sink that closes the opening, and a resin heat transfer member disposed between the circuit board and the heat sink in the axial direction and in contact with the circuit board and the heat sink, respectively.

3. The electric motor according to claim 2, wherein a heat dissipation fin is provided on the surface of the heat sink facing one side in the axial direction.

4. The electric motor according to claim 2 or 3, wherein the heat dissipation portion extends in a direction perpendicular to the axial direction and has an insulating sheet that electrically insulates the circuit board from the heat sink, the heat transfer member has a contact portion that contacts the heat sink, and the insulating sheet surrounds the contact portion when viewed from the axial direction.

5. The electric motor according to claim 4, wherein a plurality of heat dissipation fins are provided on the surface of the heat dissipation portion facing one side in the axial direction, and when viewed from the axial direction, the plurality of heat dissipation fins overlap with the contact portion.

6. The motor according to any one of claims 1 to 5, wherein the bearing holder has a plurality of protrusions projecting to one side in the axial direction, and the circuit board is held by the plurality of protrusions and the heat dissipation portion.

7. The motor according to any one of claims 1 to 6, wherein the bearing retaining portion has a retaining body portion that extends in a direction perpendicular to the axial direction, and a plurality of legs portion that protrude radially outward from the retaining body portion, the plurality of legs portion that are spaced apart from each other in a circumferential direction with respect to the central axis, and a portion of the circuit board that overlaps with the space between the legs portion when viewed from the axial direction.

8. The electric motor according to claim 7, wherein a plurality of electronic components are mounted on the other side of the circuit board facing the other side in the axial direction, in a portion that overlaps with the space between the legs when viewed from the axial direction.

9. The electric motor according to claim 8, wherein the plurality of electronic components include at least one switching element.

10. The electric motor according to any one of claims 1 to 9, wherein the rotor has an annular rotor core surrounding the shaft from the radially outward direction, and a connecting portion connecting the shaft and the rotor core, the connecting portion having an annular inner ring portion fixed to the radially outward-facing surface of the shaft, an annular outer ring portion fixed to the radially inward-facing surface of the rotor core, and a plurality of ribs connecting the inner ring portion and the outer ring portion, the plurality of ribs being spaced apart from each other in the circumferential direction about the central axis.

11. The electric motor according to claim 10, wherein each of the plurality of ribs is inclined in the circumferential direction with respect to the axial direction.

12. The electric motor according to claim 10 or 11, wherein the connecting portion has a cover portion that covers at least a part of the surface of the rotor core facing one side in the axial direction, and a plurality of protrusions that project from the cover portion to one side in the axial direction.

13. An outdoor unit comprising: an electric motor according to any one of claims 1 to 12; a blower fan rotated by the electric motor; and a heat exchanger through which the airflow generated by the blower fan passes.

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