JP7600488B2 - Motor - Google Patents

Description

The present invention relates to a motor.

Conventionally, there is a molded motor in which the stator of the motor is molded from resin to form a casing, and the rotor is supported inside the casing via bearings. This type of motor has excellent waterproofing of the stator, and excellent vibration and sound insulation against the vibration of the stator when the motor is driven. A conventional molded motor is described, for example, in JP 2007-6603 A.
JP 2007-6603 A

The DC brushless motor of JP 2007-6603 A has a stator assembly (6) in which the stator is molded as a single unit, and a rotor assembly. The bearing (5) on the non-output shaft side is supported by a bracket (10) and fixed to the stator assembly (6). A printed circuit board (8) carrying a drive IC (7) is attached to the stator assembly (6). Heat dissipation silicon (11) is applied between the bracket (10) and the drive IC (7). A heat sink (12) made of aluminum is attached to the bracket (10). This allows heat generated in the drive IC (7) to be dissipated by the bracket (10) and the heat sink (12) via the heat dissipation silicon (11) (paragraphs 0016, 0017, 0020, etc.).

The shaft (3) is fixed to the inner ring of the bearing (5). The shaft (3) is connected to a rotating part or a reduction mechanism of the equipment on which the worker performs maintenance. However, as described above, although the bearing (5) is supported by the bracket (10), only heat dissipation silicone (11) is applied between the bracket (10) and the driving IC (7). For this reason, the insulation performance between the driving IC (7) and the shaft (3) is not sufficiently ensured.

The object of the present invention is to provide a structure for a molded motor having a casing with an integrally molded stator that can ensure insulation performance between a heat dissipation component that promotes heat dissipation from electronic components housed inside and a shaft to which a rotating part or reduction gear mechanism of the device to be driven is connected.

The first exemplary invention of the present application is a motor having a stationary part and a rotating part that rotates around a central axis via a bearing part, the stationary part having a stator, a casing that houses at least a part of the stator, a cover that is fixed to the casing and directly or indirectly holds the bearing part, and a circuit board that extends in a radial direction and is electrically connected to the stator, the rotating part having a rotor and a shaft that is attached to the rotor and extends along the central axis, the circuit board has electronic components for driving the motor, and the casing has a rotor that is rotatable in at least one axial direction. The cover has an internal space that opens at a casing opening formed on the side of the bearing and continues from the casing opening to the other axial side, the electronic component is located in the internal space, the cover covers the casing opening from one axial side of the circuit board, and has a resin cover body and a heat dissipation component attached to the cover body and having a higher thermal conductivity than the cover body, the end of the heat dissipation component on the other axial side contacts the electronic component directly or indirectly via a separate member, and the cover body is interposed at least in the radial direction between the bearing and the heat dissipation component.

According to the first exemplary invention of the present application, a resin cover body, which is an insulator, is interposed between the heat dissipation component that promotes heat dissipation from the electronic components and the bearing that rotatably supports the shaft. This ensures sufficient insulation between the electronic components and heat dissipation component and the bearing that supports the shaft. As a result, it is possible to prevent electricity flowing through the circuit board from being transmitted to the shaft via the heat dissipation component and the bearing.

FIG. 1 is a vertical cross-sectional view of a motor according to a first embodiment. FIG. 2 is a perspective view of a cover and an upper bearing housing portion according to the first embodiment. FIG. 3 is a perspective view of a cover main body and an upper bearing housing portion according to the first embodiment. FIG. 4 is a perspective view of the heat dissipation component according to the first embodiment. FIG. 5 is a perspective view of the cover and the upper bearing housing according to the first embodiment. FIG. 6 is a partial vertical cross-sectional view of the motor according to the first embodiment. FIG. 7 is a perspective view of a cover and an upper bearing housing portion according to a modified example. FIG. 8 is a partial vertical cross-sectional view of a motor according to a modified example. FIG. 9 is a partial vertical cross-sectional view of a motor according to a modified example.

Below, an exemplary embodiment of the present invention will be described with reference to the drawings. In this application, the direction parallel to the central axis of the motor is called the "axial direction", the direction perpendicular to the central axis of the motor is called the "radial direction", and the direction along the arc centered on the central axis of the motor is called the "circumferential direction". In this application, the axial direction is the up-down direction, and the circuit board side with respect to the stator is called the up-down direction, and the shape and positional relationship of each part will be described. However, this definition of the up-down direction is not intended to limit the orientation of the motor according to the present invention during manufacture and use. In other words, in the following embodiments and modifications, the "upper side (upper end)" is to be read as "one axial side (end on one axial side)", and the "lower side (lower end)" is to be read as "the other axial side (end on the other axial side)". In this application, the "parallel direction" also includes a substantially parallel direction. In this application, the "orthogonal direction" also includes a substantially orthogonal direction.

1. First embodiment
<1-1. Motor configuration>
1 is a vertical cross-sectional view of a motor 1. This motor 1 is used in home appliances such as indoor and outdoor units of air conditioners. However, the motor of the present invention may be used for purposes other than home appliances. For example, the motor of the present invention may be mounted on transportation equipment such as automobiles and trains, office automation equipment, medical equipment, tools, large industrial equipment, etc., to generate various driving forces.

As shown in FIG. 1, the motor 1 has a stationary part 2 and a rotating part 3. The stationary part 2 is fixed to the frame of the device to be driven. The rotating part 3 is supported rotatably around a central axis 9 extending vertically relative to the stationary part 2 via a bearing part 60 (described later). A rotating part or a reduction mechanism of the device to be driven is fixed to a shaft 31 (described later) of the rotating part 3.

The stationary portion 2 of this embodiment has a stator 21, a casing 22, a cover 23, a circuit board 24, and a bearing housing portion 25. The bearing housing portion 25 includes an upper bearing housing portion 251 and a lower bearing housing portion 252. The upper bearing housing portion 251 forms a part of the cover 23. The lower bearing housing portion 252 forms a part of the casing 22. However, in the following, for ease of understanding, the cover 23 and the upper bearing housing portion 251 are distinguished from each other, and the casing 22 and the lower bearing housing portion 252 are distinguished from each other.

The stator 21 is an armature that generates magnetic flux in response to a drive current supplied from an external power source via a circuit board 24. The stator 21 surrounds the radial outside of the rotor 32 (described later) in an annular shape. The stator 21 has a stator core 211, an insulator 212, and a number of coils 213. The stator core 211 is made of laminated steel plates in which electromagnetic steel plates are stacked in the axial direction. The stator core 211 is fixed to the casing 22. The stator core 211 also has an annular core back 41 and a number of teeth 42 that protrude radially inward from the core back 41. The core back 41 is arranged approximately coaxially with the central axis 9. The multiple teeth 42 are arranged at approximately equal intervals in the circumferential direction.

The insulator 212 is made of resin, which is an insulating material. The insulator 212 is attached to the stator core 211. The upper surface, lower surface, and both circumferential side surfaces of each tooth 42 are covered with the insulator 212. The coil 213 is made of a conductive wire wound around the tooth 42 via the insulator 212. The insulator 212 is interposed between the stator core 211 and the coil 213, thereby preventing an electrical short circuit between the stator core 211 and the coil 213.

The casing 22 is a resin member that holds the stator 21 and the lower bearing portion 62 described below. In this embodiment, the casing 22 is an insert molded product obtained by pouring resin into a mold that holds the stator 21 and the lower bearing housing portion 252. The casing 22 has a cylindrical portion 221 and a bottom plate portion 222.

The cylindrical portion 221 extends in an approximately cylindrical shape in the axial direction. The rotor 32 is disposed radially inside the cylindrical portion 221. In this embodiment, the surfaces of the stator 21, except for the radially inner end faces of the teeth 42, are covered with the resin forming the casing 22. This makes it possible to prevent water from entering the inside of the stator 21. In addition, the coils 213 and the stator core 211 of the stator 21 can be electrically insulated. However, the entire stator 21, including the radially inner end faces of the teeth 42, may be covered with the resin forming the casing 22. In other words, the casing 22 only needs to accommodate at least a portion of the stator 21.

The bottom plate portion 222 expands in an annular shape from the lower end of the cylindrical portion 221 toward the inside in the radial direction. The bottom plate portion 222 is located below the stator 21 and the rotor 32. The bottom plate portion 222 also covers the outer peripheral surface and part of the lower surface of the lower bearing housing portion 252, and holds the lower bearing housing portion 252.

The casing 22 also has an internal space 220 that opens at a casing opening 223 at the upper end of the cylindrical portion 221 and continues downward from the casing opening 223. A circuit board 24 including electronic components 26 (described later) of the stationary portion 2, and a part of a shaft 31 (described later) and a rotor 32 (described later) of the rotating portion 3 are located in the internal space 220. This allows the entire motor 1 to be made smaller in the axial direction. However, the position at which the casing opening 223 is formed is not limited to this. The casing opening 223 may be formed on at least one of the upper and lower sides of the casing 22.

The cover 23 is disposed above the casing 22 and is a generally plate-shaped member that expands in a radial direction around the upper bearing housing 251 in an annular shape. The cover 23 in this embodiment is an insert molded product obtained by pouring resin into a mold that holds the heat dissipation component 232 and the upper bearing housing 251 described later. The resin hardens to form the cover body 231. The cover body 231 covers the outer peripheral surface and part of the lower surface of the upper bearing housing 251 and holds the upper bearing housing 251. In this way, by having the resin cover body 231, the reverberation (noise) of the cover body 231 caused by vibrations from the motor 1 can be kept lower than when a metal cover is used.

A circular recess 230 is formed on the underside of the cover 23. The recess 230 recesses upward from the underside of the periphery of the cover 23. The upper end of the cylindrical portion 221 of the casing 22 fits into the recess 230. This fixes the cover 23 and the casing 22 to each other by press-fitting. The cover 23 covers the casing opening 223 from above the circuit board 24. This prevents water and foreign matter from entering the inside of the casing 22. A more detailed structure of the cover 23 will be described later.

The circuit board 24 extends radially above the stator 21 and rotor 32 and below the cover 23. An electronic circuit including electronic components 26 for driving the motor 1 is mounted on the surface of the circuit board 24. The ends of the conductors (not shown) constituting the coil 213 are pulled out to the upper side and electrically connected to the electronic circuit. That is, the circuit board 24 is electrically connected to the stator 21. In addition, the conductors (not shown) extending from the external power source are electrically connected to the circuit board 24. That is, the coil 213 and the external power source are electrically connected via the circuit board 24. The current supplied from the external power source flows to the coil 213 via the circuit board 24. The circuit board 24 may be electrically connected to a control circuit mounted on the device to be driven, and may receive a signal line from the control circuit.

The electronic components 26 are classified into a first electronic component 261 and a second electronic component 262. The first electronic component 261 is an electronic component that is relatively prone to heat generation among the electronic components mounted on the circuit board 24. The first electronic component 261 includes, for example, a switching element such as an FET or an IGBT. The first electronic component 261 also includes a power semiconductor in which multiple switching elements are housed in one package. The second electronic component 262 is an electronic component that is relatively difficult to heat generation among the electronic components mounted on the circuit board 24. Furthermore, in this embodiment, a thermally conductive sheet 240 (separate member) that contacts the first electronic component 261 is disposed on the upper side of the circuit board 24. The material of the thermally conductive sheet 240 is, for example, an elastic sheet containing silicone rubber and having high thermal conductivity.

The upper bearing housing 251 has a generally cylindrical shape with a closed top. As described above, the cover 23 is an insert molded product obtained by pouring resin into a mold that holds the heat dissipation component 232 and the upper bearing housing 251, which will be described later. In other words, the upper bearing housing 251 is fixed to the cover body 231 of the cover 23 by molding the molded resin. The upper end of the shaft 31 and the upper bearing 61, which will be described later, are housed inside the upper bearing housing 251. The material used for the upper bearing housing 251 is a metal having electrical conductivity, such as iron or aluminum.

The lower bearing housing 252 has a generally annular shape. As described above, the casing 22 is an insert molded product obtained by pouring resin into a mold that holds the stator 21 and the lower bearing housing 252. That is, the lower bearing housing 252 is fixed to the bottom plate 222 of the casing 22 by molding the molded resin. The lower bearing housing 252 also houses a lower bearing 62 that rotatably supports the shaft 31, which will be described later. The material used for the lower bearing housing 252 is a conductive metal such as iron or aluminum.

The rotating part 3 has a shaft 31 and a rotor 32.

The shaft 31 is a columnar member extending vertically along the central axis 9. The shaft 31 is supported so as to be rotatable about the central axis 9. The lower end of the shaft 31 protrudes downward beyond the lower end of the casing 22. For example, an air conditioner fan, which is the rotating part of the device to be driven, is attached to the lower end of the shaft 31. The lower end of the shaft 31 may also be connected to a drive part other than the fan via a power transmission mechanism such as a gear.

In this embodiment, the shaft 31 protrudes downward, but the present invention is not limited to this. The shaft 31 may protrude above the cover 23, and its upper end may be connected to the drive unit. The shaft 31 may also protrude both below the casing 22 and above the cover 23, and both its lower end and upper end may be connected to the drive unit.

The rotor 32 is an annular member that is disposed radially inside the stator 21 and around the shaft 31 and rotates together with the shaft 31. The rotor 32 has a rotor core 321 and multiple magnets 322.

The rotor core 321 is made of laminated steel plates in which electromagnetic steel plates are stacked in the axial direction. A rotor through hole 320 is provided on the radially inner side of the rotor core 321. The rotor through hole 320 penetrates the rotor 32 in the axial direction along the central axis 9. The shaft 31 is inserted into the rotor through hole 320 and attached to the inner peripheral surface of the rotor core 321 by press-fitting. However, the shaft 31 may be attached to the rotor core 321 by adhesion instead of or in addition to the press-fitting.

The multiple magnets 322 are arranged around the rotor core 321. The radially outer surface of each magnet 322 is a magnetic pole face that faces the radially inner end face of the teeth 42 of the stator 21. The multiple magnets 322 are arranged at equal intervals in the circumferential direction so that the north pole faces and the south pole faces are arranged alternately.

In addition, a ring-shaped magnet may be used instead of the multiple magnets 322. When using a ring-shaped magnet, it is sufficient that the outer peripheral surface of the magnet is magnetized with alternating north and south poles in the circumferential direction. In addition, the multiple magnets 322 may be arranged around the rotor core 321 as in this embodiment, or may be arranged in a state where they are embedded inside the rotor core 321.

The bearing portion 60 includes an upper bearing portion 61 and a lower bearing portion 62. The upper bearing portion 61 rotatably supports the shaft 31 above the rotor 32. The lower bearing portion 62 rotatably supports the shaft 31 below the rotor 32. In this embodiment, the upper bearing portion 61 and the lower bearing portion 62 are both ball bearings having a sphere 601, an outer ring 602, and an inner ring 603. In the ball bearing, the outer ring 602 and the inner ring 603 rotate relative to each other via the sphere 601. The sphere 601, the outer ring 602, and the inner ring 603 are made of a conductive metal such as iron. That is, the outer peripheral surface and the inner peripheral surface of both the upper bearing portion 61 and the lower bearing portion 62 are connected by a conductive member.

In this embodiment, the entire sphere 601, outer ring 602, and inner ring 603 are made of a conductive material, but the present invention is not limited to this. For example, even if an insulating material is used for a part of the upper bearing portion 61 and the lower bearing portion 62, it is sufficient that the outer peripheral surface and the inner peripheral surface of the upper bearing portion 61 and the lower bearing portion 62 are connected by a conductive member. In addition, although a ball bearing is used as the bearing in this embodiment, other types of bearings such as a sleeve bearing may be used as long as the outer peripheral surface and the inner peripheral surface of the bearing are conductive.

The outer ring of the upper bearing portion 61 is fixed to the upper bearing housing portion 251. As a result, the outer ring of the upper bearing portion 61 is electrically connected to the upper bearing housing portion 251. The outer ring of the lower bearing portion 62 is fixed to the lower bearing housing portion 252. As a result, the outer ring of the lower bearing portion 62 is electrically connected to the lower bearing housing portion 252. In addition, the inner rings of each of the upper bearing portion 61 and the lower bearing portion 62 are fixed to the shaft 31.

When the motor 1 is driven, electricity is applied from an external power source to the first electronic component 261 and the second electronic component 262 on the circuit board 24. The first electronic component 261 and the second electronic component 262 generate a drive current for applying electricity to the coil 213 and control the current application. When the drive current is supplied to the coil 213, a magnetic flux is generated in the multiple teeth 42 of the stator core 211. Then, a circumferential torque is generated by the action of the magnetic flux between the teeth 42 and the magnets 322 mounted on the rotor 32. As a result, the rotating part 3 rotates around the central axis 9. In addition, devices directly or indirectly attached to the shaft 31 rotate together with the rotating part 3.

As described above, the upper bearing portion 61 is supported by the metallic upper bearing housing portion 251. The lower bearing portion 62 is supported by the metallic lower bearing housing portion 252. This prevents relative dimensional changes and deformation between the upper bearing portion 61 and the upper bearing housing portion 251, and between the lower bearing portion 62 and the lower bearing housing portion 252, even if the temperature of each portion rises when the motor 1 is in operation. This prevents the rotating portion 3 from spinning freely, and maintains high rotational accuracy.

<1-2. Detailed structure of the cover>
Next, the structure of the cover 23 will be described in more detail.

Figure 2 is a perspective view of the cover 23 and the upper bearing housing section 251. As shown in Figure 2, the cover 23 has the above-mentioned cover body section 231 and the heat dissipation component 232. The cover body section 231 is made of resin. On the other hand, the heat dissipation component 232 is made of a metal such as aluminum. Therefore, the heat dissipation component 232 has a higher thermal conductivity than the cover body section 231.

Figure 3 is a perspective view of the cover body 231 and the upper bearing housing 251 as viewed from above. Figure 4 is a perspective view of the heat dissipation component 232. Figure 5 is a perspective view of the cover 23 and the upper bearing housing 251 as viewed from below. As shown in Figure 3, the cover body 231 formed by resin injection molding has a plate-shaped portion 51 and a hole portion 52. The plate-shaped portion 51 spreads in a plate-like shape in the horizontal direction. The hole portion 52 is a trace where the heat dissipation component 232 was placed during resin injection molding, and penetrates the plate-shaped portion 51 in the axial direction. That is, as shown in Figures 2 to 4, in the cover 23 formed by resin injection molding, the heat dissipation component 232 is placed in the hole portion 52 and attached to the cover body 231. Also, as shown in Figure 5, the heat dissipation component 232 is exposed below the cover 23.

1, the lower end of the heat dissipation component 232 indirectly contacts the first electronic component 261 through the heat conduction sheet 240 having a high thermal conductivity. Also, as shown in FIG. 2 and FIG. 4, the upper surface of the heat dissipation component 232 is provided with a plurality of fins 71 exposed to the outside of the motor 1. Each fin 71 is a protrusion protruding upward. This allows the heat generated in the first electronic component 261 to be dissipated from the heat dissipation component 232 to the outside of the motor 1 through the heat conduction sheet 240. In particular, in this embodiment, the heat dissipation component 232 is exposed below the cover 23 and directly contacts the heat conduction sheet 240 without an air layer, thereby further improving the heat dissipation performance. Note that the heat conduction sheet 240 may not be provided. That is, the lower end of the heat dissipation component 232 may directly contact the first electronic component 261 without the heat conduction sheet 240.

The second electronic component 262, which is relatively less susceptible to heat generation, is spaced axially from the plate-shaped portion 51 of the cover 23. The second electronic component 262 includes, for example, an IC component. In addition, the lower end of the heat dissipation component 232 in this embodiment is located below the plate-shaped portion 51. This allows the first electronic component 261 to come into contact with the heat dissipation component 232 without the second electronic component 262 coming into contact with the cover main body portion 231.

As shown in FIG. 4, the heat dissipation component 232 has a fixing portion 72 provided on the horizontal outer side of the multiple fins 71. The fixing portion 72 extends approximately perpendicular to the axial direction. However, the fixing portion 72 may be slightly inclined from the direction approximately perpendicular to the axial direction. When the cover 23 is resin molded, the heat dissipation component 232 is fixed by covering the side surface 721 of the fixing portion 72 and the lower end surface 722 of the fixing portion 72 with the resin forming the cover body portion 231. This prevents the heat dissipation component 232 from coming off the cover body portion 231 in the axial direction. In addition, since the heat dissipation component 232 can be attached to the cover body portion 231 without using screws, adhesives, etc., there is almost no gap between the heat dissipation component 232 and the cover body portion 231. Therefore, even if water is splashed on the cover 23 from the outside of the motor 1, it is possible to prevent the water from entering the inside of the motor 1. However, the side surface 721 of the fixing portion 72 and the upper end surface 723 of the fixing portion 72 may be covered by the resin that forms the cover body portion 231. In other words, the side surface 721 of the fixing portion 72 and at least a part of the upper end surface 723 and the lower end surface 722 of the fixing portion 72 may be covered by the resin that forms the cover body portion 231 to fix the heat dissipation component 232.

As shown in FIG. 4, the heat dissipation component 232 further has an axial extension 73 extending in the axial direction below the multiple fins 71. Also, as shown in FIG. 5, the cover body 231 has a first protrusion 53. The first protrusion 53 protrudes downward from the plate-shaped portion 51 at the periphery of the hole 52. In this embodiment, the entire side surface of the axial extension 73 of the heat dissipation component 232 is covered with the resin that forms the first protrusion 53. This increases the area of the heat dissipation component 232 covered by the resin that forms the cover body 231. As a result, even if the heat dissipation component 232 receives an external force, it is suppressed from tilting or falling. However, it is sufficient that at least a part of the side surface of the axial extension 73 of the heat dissipation component 232 is covered with the resin that forms the cover body 231.

3, a step 521 is formed on the periphery of the hole 52 at the upper end of the cover body 231. The step 521 is recessed downward from the upper surface of the plate-shaped portion 51. The step 521 is wider in the direction perpendicular to the axial direction than other portions of the hole 52. The step 521 is provided with a lower portion of the fins 71 of the heat dissipation component 232 and a fixing portion 72. That is, the lower portion of the fins 71 of the heat dissipation component 232 is located in the hole 52, and the portion protruding above the cover body 231 is reduced. This allows the axial height of the motor 1 to be reduced. However, by providing the step 521 deeper, all of the fins 71 of the heat dissipation component 232 may be located in the hole 52.

Figure 6 is a partial vertical cross-sectional view of the motor 1. As shown in Figure 6, the upper bearing housing 251 has a cylindrical portion 91 and a flange portion 92. The cylindrical portion 91 extends cylindrically along the central axis 9. The upper bearing portion 61 is disposed inside the cylindrical portion 91. The flange portion 92 extends radially outward from the lower end of the cylindrical portion 91. The cover body 231 has a second protruding portion 54 having an annular shape. The second protruding portion 54 protrudes downward from the radially inner end of the plate-shaped portion 51. A circumferential portion of the second protruding portion 54 constitutes a part of the first protruding portion 53 described above. The flange portion 92 of the upper bearing housing 251 is covered with a resin that forms the second protruding portion 54.

This forms a structure in which a part of the resin cover body 231, which is an insulator, is interposed between the upper bearing housing 251 and the upper bearing 61 and the heat dissipation component 232 and the electronic component 26. As a result, electrical insulation performance between the upper bearing housing 251 and the upper bearing 61 and the heat dissipation component 232 and the electronic component 26 is sufficiently ensured. Then, electricity flowing through the circuit board 24 on which the first electronic component 261 and the second electronic component 262 are mounted is suppressed from being transmitted to the shaft 31 via the heat dissipation component 232, the upper bearing housing 251, and the upper bearing 61. In particular, in this embodiment, the second protrusion 54 extending in the axial direction is interposed between the upper bearing housing 251 and the upper bearing 61 and the electronic component 26, thereby ensuring a longer insulation distance.

In addition, by resin molding the cover 23 having such a structure, it is possible to simultaneously form a structure capable of insulating the heat dissipation components 232 and electronic components 26 from the upper bearing portion 61, and the upper bearing housing portion 251 that holds the upper bearing portion 61. This allows the manufacturing process to be shortened. In addition, in this embodiment, the cylindrical portion 91 of the upper bearing housing portion 251 is located lower than the upper end portion of the motor 1. This reduces the axial height of the motor 1 while maintaining the fixing strength of the upper bearing housing portion 251 to the cover body portion 231.

As shown in FIG. 4, the fixing portion 72 of the heat dissipation component 232 forms a base shape extending perpendicularly to the axial direction from the multiple fins 71. Also, as shown in FIG. 2, the upper end face of the base shape is an exposed surface 724 exposed from the cover body 231 to the outside of the motor 1. When the cover 23 is resin molded, the peripheral portion of the multiple fins 71 is pressed from above by a mold to prevent the heat dissipation component 232 inserted into the cover 23 from floating up. As a result, after resin molding, the peripheral portion of the multiple fins 71 becomes the exposed surface 724 exposed to the outside. If water is splashed on the cover 23 from outside the motor 1, water is likely to accumulate on the exposed surface 724.

Therefore, in this embodiment, a groove 55 is further formed in the cover body 231. The groove 55 is recessed downward from a part of the upper end face of the cover body 231, and connects the outer peripheral surface of the cover body 231 and the hole 52. The groove 55 is also continuous with the exposed surface 724. As a result, even if water is splashed onto the cover 23 from outside the motor 1, it can be drained through the groove 55 without accumulating on the exposed surface 724.

2. Modifications
Although the exemplary embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

The upper bearing housing 251 and the lower bearing housing 252 may not be provided. For example, the upper bearing 61 may be fixed directly to the cover body 231 of the cover 23 without the upper bearing housing 251. That is, the cover 23 may be configured to hold the upper bearing 61 directly or indirectly. A part of the cover body 231 made of resin, which is an insulator, may be interposed between the upper bearing 61 and the heat dissipation component 232 at least in the radial direction. This ensures sufficient electrical insulation between the upper bearing 61 and the heat dissipation component 232 and the electronic component 26. The lower bearing 62 may be fixed directly to the bottom plate 222 of the casing 22 without the lower bearing housing 252. That is, the casing 22 may be configured to hold the lower bearing 62 directly or indirectly.

Figure 7 is an oblique view of cover 23B and upper bearing housing according to one modified example, viewed from above. In the example of Figure 7, surface 234B of cover body 231B that constitutes hole 52B inclines in a direction away from the radial center of hole 52B as it moves upward. In other words, hole 52B increases in radial width as it moves upward. This allows air to flow smoothly from outside motor 1 into hole 52B and then out of hole 52B to the outside of motor 1. As a result, the heat dissipation performance of heat dissipation component 232B is further improved.

Figure 8 is a partial vertical cross-sectional view of a motor 1C according to another modified example. As shown in the example of Figure 8, the fixing portion 72C of the heat dissipation component 232C may be slightly inclined with respect to the horizontal direction. Even in this case, the side surface 721C of the fixing portion 72C of the heat dissipation component 232C and at least a part of the upper end surface 723C and the lower end surface 722C of the fixing portion 72C are firmly fixed by being covered with the resin that forms the cover body portion 231C.

Figure 9 is a partial vertical cross-sectional view of a motor 1D according to another modified example. In the example of Figure 9, the heat dissipation component 232D has multiple fins 71D, a fixed portion 72D, and an axial extension portion 73D. The axial extension portion 73D extends in the axial direction below the multiple fins 71D. The fixed portion 72D extends approximately perpendicular to the axial direction outside the lower end of the axial extension portion 73D. The heat dissipation component 232D is firmly fixed by covering the side surface 721D of the fixed portion 72D and the upper end surface 723D of the fixed portion 72D with the resin that forms the cover main body portion 231D. Furthermore, by having such a structure, the heat dissipation component 232D is prevented from coming off or falling off the cover 23D.

The detailed shape of each component may differ from the shape shown in each drawing of this application. Furthermore, the elements appearing in the above-mentioned embodiments and variations may be combined as appropriate to the extent that no contradiction occurs.

This invention can be used in motors.

1, 1C, 1D Motor 2 Stationary portion 3 Rotating portion 9 Central shaft 21 Stator 22 Casing 23, 23B, 23D Cover 24 Circuit board 25 Bearing storage portion 26 Electronic component 31 Shaft 32 Rotor 41 Core back 42 Teeth 51 Plate-shaped portion 52, 52B Hole portion 53 First protrusion 54 Second protrusion 55 Groove portion 60 Bearing portion 61 Upper bearing portion 62 Lower bearing portion 71, 71D Fins 72, 72C, 72D Fixed portion 73, 73D Axial extension portion 91 Cylindrical portion 92 Flange portion 211 Stator core 212 Insulator 213 Coil 220 Internal space 223 Casing opening 231, 231B, 231C, 231D Cover main body portion 232, 232B, 232C, 232D Heat dissipation component 240 Heat conductive sheet 251 Upper bearing housing portion 252 Lower bearing housing portion 261 First electronic component 262 Second electronic component 724 Exposed surface

Claims (9)

A motor,
A stationary portion;
a rotating part that rotates around a central axis via a bearing part;
having
The stationary portion is
A stator;
a casing that accommodates at least a portion of the stator;
a cover fixed to the casing and directly or indirectly holding the bearing portion;
A circuit board extending in a radial direction and electrically connected to the stator;
having
The rotating part is
A rotor;
a shaft attached to the rotor and extending along the central axis;
having
The circuit board includes:
Electronic components for driving the motor are included,
the casing has an internal space that is open at least at a casing opening formed on one axial side and continues from the casing opening to the other axial side,
the electronic component is located in the internal space,
The cover covers the casing opening from one axial side of the circuit board, and
A resin cover body;
a heat dissipation component attached to the cover body and having a higher thermal conductivity than the cover body;
having
an end portion of the heat dissipation component on the other axial side contacts the electronic component directly or indirectly via a separate member;
the cover body is interposed between the bearing portion and the heat dissipation component at least in a radial direction,
The cover is
a metal bearing housing portion fixed to the cover body portion and having the bearing portion disposed therein;
The cover body portion is
A plate-shaped portion extending in a plate shape is provided.
The bearing housing portion is
a cylindrical portion in which the bearing portion is disposed and which extends cylindrically along the central axis;
a flange portion extending radially outward from the other axial end of the cylindrical portion;
having
The cover body portion is
The plate-shaped portion further includes a second protruding portion protruding from a radially inner end portion of the plate-shaped portion toward the other axial side,
The flange portion is covered with a resin that forms the second protrusion portion. 2. The motor according to claim 1,
The cover body is interposed between the bearing housing portion and the heat dissipation component. 3. The motor according to claim 2,
The cover body portion is
The plate-shaped portion further has a hole passing through the plate-shaped portion in the axial direction,
the heat dissipation component is disposed in the hole, and an end portion on the other axial direction side of the heat dissipation component is located on the other axial direction side of the plate-shaped portion,
The electronic component includes a first electronic component and a second electronic component,
the first electronic component is in contact with the heat dissipation component directly or indirectly via another member;
The second electronic component is spaced apart from the plate-shaped portion. 4. The motor according to claim 3,
The heat dissipation component is
A fixing portion extending perpendicular to the axial direction,
The heat dissipation component is fixed to the motor by covering the side surfaces of the fixed portion and at least a portion of the end faces on one axial side and the other axial side of the fixed portion with resin that forms the cover main body portion. The motor according to claim 3 or claim 4,
The heat dissipation component is
The motor further includes a plurality of fins exposed to an outside thereof,
a motor in which some or all of the plurality of fins on the other axial side are positioned in the hole portion. A motor according to any one of claims 3 to 5,
The cover body portion is
a first protruding portion protruding from the plate-like portion toward the other axial side at a peripheral edge of the hole,
At least a portion of a side surface of the heat dissipation component is covered with the resin that forms the first protrusion. 4. The motor according to claim 3,
The cylindrical portion is located on the other axial side of the one axial end of the motor. A motor according to any one of claims 1 to 7,
The heat dissipation component of the motor is made of metal. A motor,
A stationary portion;
a rotating part that rotates around a central axis via a bearing part;
having
The stationary portion is
A stator;
a casing that accommodates at least a portion of the stator;
a cover fixed to the casing and directly or indirectly holding the bearing portion;
A circuit board extending in a radial direction and electrically connected to the stator;
having
The rotating part is
A rotor;
a shaft attached to the rotor and extending along the central axis;
having
The circuit board includes:
Electronic components for driving the motor
having
the casing has an internal space that is open at least at a casing opening formed on one axial side and continues from the casing opening to the other axial side,
the electronic component is located in the internal space,
The cover covers the casing opening from one axial side of the circuit board, and
A resin cover body;
a heat dissipation component attached to the cover body and having a higher thermal conductivity than the cover body;
having
the other axial end of the heat dissipation component indirectly contacts the electronic component via a separate member;
the cover body is interposed between the bearing portion and the heat dissipation component at least in a radial direction,
The cover body portion is
A plate-like portion that expands like a plate;
a hole portion passing through the plate-shaped portion in an axial direction;
having
The cover body portion is
a first protruding portion protruding from the plate-shaped portion toward the other axial side at a peripheral edge of the hole;
and
At least a portion of a side surface of the heat dissipation component is covered with a resin that forms the first protrusion,
At least a portion of the end portion on the other axial side of the first protrusion contacts the separate member.

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