WO2022209762A1

WO2022209762A1 - Electric motor

Info

Publication number: WO2022209762A1
Application number: PCT/JP2022/010907
Authority: WO
Inventors: パーオブトンパッタラワディー
Original assignee: 株式会社富士通ゼネラル
Priority date: 2021-03-29
Filing date: 2022-03-11
Publication date: 2022-10-06
Also published as: JP7255621B2; CN117044086A; JP2022152645A

Abstract

[Problem] To provide an electric motor capable of stably dissipating heat generated from a circuit board. [Solution] The electric motor according to the one embodiment of the present invention comprises: a heat sink that covers an opening end portion of a cylindrical resin outer shell; and a circuit board disposed in an internal space covered by the resin outer shell and the heat sink. The heat sink has: a disc portion; an annular protruding portion that protrudes from the disc portion toward the circuit board side in the axial direction; and a projecting portion which is disposed on the inner diameter side of the resin outer shell relative to the annular protruding portion and which protrudes from the disc portion toward the circuit board side to come into thermal contact with the circuit board. The disc portion has an axial-direction positioning portion that abuts against the opening end portion of the resin outer shell, and the annular protruding portion has a radial-direction positioning portion that abuts against the inner peripheral surface or outer peripheral surface of the resin outer shell.

Description

Electric motor

The present invention relates to an electric motor, and more particularly to a heat dissipation structure for a circuit board built into the electric motor.

　Conventionally, there has been known an electric motor provided with a circuit board inside the electric motor for controlling the rotational drive of the electric motor. Electric motors having heat sinks are also known in which the circuit board includes electronic components that generate heat when energized, and the heat generated by the electronic components is dissipated to the outside of the motor.

For example, in Patent Document 1, a resin for molding a stator core (hereinafter referred to as a resin shell) and a bearing on the non-output side of the motor are supported and attached to the end of the resin shell on the non-output side of the motor. a metal bracket; a radiation fin (heat sink) fixed to an end of the resin shell via the metal bracket and including projections that can be inserted into holes provided on the outer surface of the metal bracket; A brushless motor is provided with a circuit board disposed inside, and a structure is described in which the protrusions are brought into contact with electronic components on the circuit board via thermally conductive resin.

JP 2009-131127 A

In Patent Document 1, heat radiation fins as heat sinks are fixed to the ends of the resin shell via metal brackets. However, motors with heat sinks are subject to dimensional variations and assembly variations. Dimensional variations are variations in the dimensions of each part itself. Assembly variations are variations in the relative positions of the parts (the position of one part when the position of the other part is used as a reference) that occurs when the parts are assembled. In particular, when the heat sink is formed by casting (die casting), the dimensional accuracy of the heat sink itself tends to be low, and dimensional variations tend to increase.

Therefore, in the structure of Patent Document 1, in which the heat sink (radiating fin) is fixed to the end of the resin shell via a metal bracket, the above-described shaft between the heat sink and the end of the resin shell may be affected by the various variations in the electric motor. Variations in direction and radial relative position are likely to occur. As a result, variations in relative positions in the axial and radial directions between the protrusions of the heat sink and the circuit board are likely to occur, and gaps may occur between the electronic components of the circuit board and the protrusions of the heat sink. , there is a possibility that sufficient heat dissipation cannot be performed (that is, the heat dissipation performance is lowered).

In view of the circumstances as described above, an object of the present invention is to provide an electric motor that can stably dissipate heat generated in a circuit board.

An electric motor according to one aspect of the present invention includes: a cylindrical resin shell having an open end on one end in an axial direction; a stator core integrally formed with the resin shell; and an inner diameter side of the stator core. a rotor arranged in the inner space, a heat sink covering the open end of the resin shell, and a circuit board arranged in an internal space covered with the resin shell and the heat sink. The heat sink includes a disk portion, an annular protrusion projecting from the disk portion toward the circuit board in the axial direction, and an inner diameter side of the resin outer shell relative to the annular protrusion. a projecting portion projecting from the terminal toward the circuit board side and in thermal contact with the circuit board. The disc portion has an axial positioning portion that contacts the open end of the resin shell, and the annular protrusion has a radial positioning portion that contacts the inner or outer peripheral surface of the resin shell. .

According to the electric motor, the axial positioning portion abuts the opening end portion of the resin outer shell, and the radial positioning portion abuts the inner peripheral surface or the outer peripheral surface of the resin outer shell, whereby the heat sink is provided. Positional accuracy in the axial direction and the radial direction between the protrusion and the circuit board is ensured. Thereby, the heat generated in the circuit board can be stably dissipated through the heat sink.

The radial positioning portion may be formed on the outer peripheral surface of the annular projecting portion and may abut on the inner peripheral surface of the resin outer shell.

The axial positioning portion may be located on the outer peripheral side of the annular protrusion of the disk portion.

The protrusion height in the axial direction of the protrusion may be greater than the protrusion height of the annular protrusion.

The circuit board may include a wiring board and an electronic component mounted on the wiring board that generates heat when energized, and the protrusion may have a facing surface facing the electronic component.

The cylindrical resin shell may have a mounting surface to which the circuit board is fixed.

The heat sink may further have a bearing accommodating portion that accommodates a first bearing that rotatably supports the rotating shaft.

A method of manufacturing an electric motor according to one embodiment of the present technology forms the heat sink by die casting.

According to the present invention, the heat generated in the circuit board can be stably dissipated.

1 is a cross-sectional view of an electric motor according to a first embodiment of the present invention; FIG. 4 is a perspective view of a resin outer shell in the electric motor; FIG. It is a perspective view of the heat sink in the said electric motor, Comprising: (A) is a top side perspective view, (B) is a back side perspective view. FIG. 4A is a cross-sectional view showing a process for processing a heat sink in the electric motor, wherein (A) is a cross-sectional view showing a process for processing a radial positioning portion, and (B) is a process for processing an axial positioning portion and a facing surface; It is a sectional view. FIG. 7 is a cross-sectional view of a main part of an electric motor according to a second embodiment of the invention;

Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and may differ from reality. Therefore, specific components should be determined with reference to the following description.

Further, the embodiments shown below are examples of apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is based on the shape, structure, arrangement, etc. of the component parts. It is not specific to the following. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

<First embodiment>
FIG. 1 is a cross-sectional view of an electric motor 1 according to the first embodiment. The electric motor 1 of the present embodiment is used, for example, as a rotational drive source for a blower fan mounted in an indoor unit of an air conditioner.

[Overall configuration of electric motor]
The electric motor 1 includes a stator core 21 , a rotor 3 , a resin shell 10 , a first bearing 71 , a second bearing 81 , a heat sink 4 and a circuit board 5 .

The stator core 21 is integrally formed with the resin outer shell 10 .
The rotor 3 is fixed to the rotating shaft 6 and arranged on the inner diameter side of the stator core 21 .
The resin shell 10 has a cylindrical shape having an open end 101 at one end in a direction parallel to the axis C of the rotating shaft 6 (hereinafter also referred to as an axial direction).
The heat sink 4 is arranged to cover the open end 101 of the resin shell 10 .
The circuit board 5 is arranged in an internal space covered with the resin shell 10 and the heat sink 4 .

In the following, as an example, an inner rotor type brushless DC motor in which a cylindrical rotor 3 having a permanent magnet portion 31 is rotatably disposed radially inside a cylindrical stator 2 that generates a rotating magnetic field will be described. A motor 1 will be described. The electric motor 1 is of course not limited to this, and may be, for example, an outer rotor type brushless DC motor, an AC motor, or another electric motor.

Also, in the following description, the axis C of the rotating shaft 6 is also the central axis of the electric motor 1, that is, the rotating shaft of the rotor 3. The radial direction is a direction passing through the axis C and orthogonal to the axial direction. The inner diameter side is the inner side in the radial direction, and the outer diameter side is the outer side in the radial direction. Furthermore, the circumferential direction is the direction of rotation about the axis C. As shown in FIG.

(rotor)
The rotor 3 has an annular permanent magnet portion 31 and a rotor main body 30 . The rotor main body 30 has an outer peripheral surface and an inner peripheral surface. A permanent magnet portion 31 is fixed to the outer peripheral surface of the rotor main body 30 . A rotary shaft 6 is fixed to the inner peripheral surface of the rotor main body. As a result, the rotating shaft 6 rotates integrally with the rotor main body 30 .

The rotor 3 is a surface magnet type in which a permanent magnet portion 31 is annularly fixed to the outer peripheral surface. The permanent magnet portion 31 is annularly formed of a plurality of (e.g., 8 or 10) permanent magnets so that N poles and S poles appear alternately at equal intervals in the circumferential direction. The permanent magnet portion 31 is typically made of a sintered metal such as an Nd--Fe--B alloy. A plastic magnet may also be used.

As shown in FIG. 1, the rotor body 30 has an outer core 32, an insulating member 33, and an inner core .

The outer core 32 is annular and forms the outer peripheral surface of the rotor main body 30 . The outer core 32 is a laminate of plates made of a soft magnetic material such as a plurality of electromagnetic steel plates. The inner peripheral iron core 34 is formed in an annular shape and forms the inner peripheral surface of the rotor main body 30 .
The inner peripheral core 34 is a laminate of plates made of a soft magnetic material such as a plurality of electromagnetic steel plates. The rotating shaft 6 is fixed to the center of the inner peripheral iron core 34 by press fitting or caulking.

The insulating member 33 electrically insulates between the outer core 32 and the inner core 34 . As a result, the difference between the static capacitance on the stator side and the static capacitance on the rotor side of the electric motor 1 can be reduced, and electrolytic corrosion of the

bearings

71 and 81 can be suppressed. The insulating member 33 is made of dielectric resin such as PBT (polybutylene terephthalate) or PET (polyethylene terephthalate), and is fixed between the outer core 32 and the inner core 34 . The insulating member 33 may be an annular molded body, or may be a resin material filled between the outer core 32 and the inner core 34 by insert molding or the like.

(stator)
The stator 2 includes a stator core 21 having a cylindrical yoke portion and a plurality of teeth extending radially from the yoke, and windings (coils) 22 wound around the teeth. there is The stator core 21 is, for example, a laminate of plates made of a soft magnetic material such as a plurality of electromagnetic steel plates. The outer peripheral surface of the stator 2 (stator core 21) is covered with a resin shell 10 (see FIG. 1). The stator 2 is arranged such that the permanent magnet portion 31 of the rotor 3 faces the stator core 21 of the stator 2 in the radial direction via an air gap (magnetic gap).

(Resin shell)
The resin shell 10 is made of an insulating resin material. FIG. 2 is a perspective view of the resin shell 10 in the electric motor 1, and as shown in FIG. It is formed in a hollow cylindrical shape with Here, the counter-output end portion 61 is the end portion of the rotary shaft 6 opposite to the output end portion 62 . The output end portion 62 is the end portion of the electric motor 1 on the load side (the side connected to the load).
As described above, the resin shell 10 is integrally molded with the stator 2 . The resin material forming the resin shell 10 is not particularly limited, and is formed of, for example, BMC (Bulk Molding Compound: unsaturated polyester resin) resin.

Also, the resin shell 10 has a mounting surface 9 . The mounting surface 9 is formed on the side of the inner peripheral surface 10a of the resin outer shell 10, is an inner peripheral plane perpendicular to the axial direction, and is axially opposite to the rotor 3 with a gap therebetween. It is provided on the end portion 61 side. The mounting surface 9 supports the circuit board 5 which will be described later. In the present embodiment, the mounting surface 9 is the surface of the counter-output end portion 61 side of the step provided so as to protrude from the inner peripheral surface 10a of the resin outer shell 10 toward the inner diameter side. The mounting surface 9 may be formed continuously in the circumferential direction of the inner peripheral surface 10a of the resin outer shell 10, or may be formed at a plurality of locations at intervals in the circumferential direction.

The resin outer shell 10 further has a second bearing accommodating portion 82 that accommodates a second bearing 81, which will be described later. The general shape of the second bearing accommodating portion 82 is a cylindrical shape centered on the axis C and one end side of which is closed. The second bearing accommodating portion 82 is provided on the bottom portion 102 of the resin outer shell 10 on the side opposite to the open end portion 101 .

(circuit board)
The circuit board 5 includes a wiring board 50 and an electronic component 51 mounted on the surface of the wiring board 50 (the surface on the side opposite to the output end 61 of the rotary shaft 6) and generating heat when energized. The circuit board 5 is generally disc-shaped, and the periphery of the circuit board 5 is supported by the mounting surface 9 and fixed by, for example, adhesion, adhesion, screw fastening, soldering, or the like. A positioning protrusion may be provided on the peripheral edge of the circuit board 5, and a positioning recess may be provided on the inner peripheral surface 10a of the resin shell 10 to engage with the protrusion. It can be fixed to the mounting surface 9 while being positioned in the circumferential direction.

The electronic components 51 that generate heat when energized are mainly semiconductor package components such as power supply ICs and motor drive current control ICs, but may also include passive components such as capacitors. In addition to the electronic component 51, the wiring board 50 is mounted with other components such as a connector component to be connected to a power cable, but illustration of these components is omitted. The power cable is connected to a power source (not shown) through a cable insertion portion 105 formed in the vicinity of the open end portion 101 of the resin shell 10 over a predetermined angular range in the circumferential direction.

As shown in FIG. 2, the mounting surface 9 is provided with a plurality of (two in this example) positioning pins 9c penetrating the circuit board 5 .
Further, the inner peripheral surface 10a of the resin outer shell 10 may be partially provided with a positioning recess 104 for accommodating the circuit board 5. This also allows the circuit board 5 to be positioned on the mounting surface 9 in a state of being positioned in the circumferential direction. can be fixed to
2 is formed to be electrically connected to the circuit board 5, and the circuit board 5 is positioned on the mounting surface 9 by a plurality of positioning pins 9c. At the same time, it is fixed on the mounting surface 9 by soldering the circuit board 5 and the end portion 221 of the coil.

(bearing)
As shown in FIG. 1, the first bearing 71 is a ball bearing having an outer ring 711, an inner ring 712, a plurality of balls 713, and the like. The second bearing 81 is a ball bearing having an outer ring 811, an inner ring 812, balls 813, and the like.

The outer ring 711 of the first bearing 71 is fixed to the heat sink 4 (first bearing housing portion 41), and the inner ring 712 of the first bearing 71 is fixed to the counter-output end portion 61 side of the rotary shaft 6. The outer ring 813 of the second bearing 81 is fixed to the resin outer shell 10 (second bearing accommodating portion 82 ), and the inner ring 812 of the second bearing 81 is fixed to the output end portion 62 of the rotary shaft 6 . As a result, the rotating shaft 6 is rotatably supported around the axis C with respect to the heat sink 4 and the resin shell 10 by the first bearing 71 and the second bearing 81 .

(heatsink)
The heat sink 4 has a first bearing accommodating portion 41 , a disk portion 42 , an annular projecting portion 43 and a projecting portion 44 . The heat sink 4 is attached and fixed to the open end 101 of the resin shell 10 . The heat sink 4 is made of a metal material having excellent thermal conductivity, such as aluminum. The heat sink 4 is integrally formed with a disk portion 42, an annular projecting portion 43, and a projecting portion 44, respectively. The heat sink 4 is molded by die casting (casting), for example.

The heat sink 4 functions as a cover member (bracket) that closes the opening of the resin outer shell 10 by covering the opening end 101 of the resin outer shell 10, and a bearing housing part (bearing house) that supports the first bearing 71. and a function as a heat radiating member that radiates heat generated by the electronic components 51 inside the motor to the outside of the motor. The heat sink 4 is fixed to the open end 101 of the resin outer shell 10 using a plurality of unillustrated screw members.

3(A) is a perspective view of the inner side of the heat sink 4 (lower side in FIG. 1), and FIG. 3(B) is a perspective view of the outer side of the heat sink 4 (upper side in FIG. 1).

The disk portion 42 is an annular plate portion having a center hole 40 centered on the axis C. In this embodiment, the outer diameter of the disc portion 42 is the same or substantially the same size as the outer diameter of the open end portion 101 of the resin shell 10 . As shown in FIGS. 3A and 3B, the disk portion 42 has an upper surface 423 and a rear surface 424 on the opposite side. As will be described later, the upper surface portion 423 of the disc portion 42 is formed with the first bearing accommodating portion 41 . A rear surface 424 of the disk portion 42 is provided with the axial positioning portion 420 , the annular projection portion 43 and the projection portion 44 .

The annular projecting portion 43 is formed so as to project from the rear surface 424 side of the disk portion 42 toward the circuit board 5 side. Further, the annular projecting portion 43 has a radial positioning portion 430 that contacts the inner peripheral surface 10 a of the resin outer shell 10 .

The projecting portion 44 is arranged on the inner diameter side of the annular projecting portion 43, projects from the back surface 424 side of the disk portion 42 toward the circuit board 5 side, and thermally contacts the circuit board 5 (the electronic component 51 in this embodiment). come into contact with In this embodiment, as shown in FIG. 1, when the heat sink 4 is attached to the resin outer shell 10, the protrusion 44 is formed in a region between the first bearing accommodating portion 41 and the annular protrusion 43 in the radial direction. It is arranged and faces the electronic component 51 .
The details of each unit will be described below.

(First bearing accommodating portion)
The first bearing housing portion 41 houses the first bearing 71 . The first bearing accommodating portion 41 has a cylindrical shape with one end side centered on the axis C and is closed, and accommodates the first bearing 71 . The first bearing accommodating portion 41 is formed on the upper surface 423 side of the inner peripheral edge portion 401 of the center hole 40 of the disc portion 42 .

(Disc part)
The disk portion 42 has an axial positioning portion 420 . As shown in FIG. 3A, the axial positioning portion 420 is formed on the rear surface 424 side of the outer peripheral edge portion 422 of the disc portion 42 . In this embodiment, the outer peripheral edge portion 422 is a region of the disk portion 42 on the outer diameter side of the annular projecting portion 43 .

The axial thickness of the disk portion 42 in the region on the inner diameter side of the outer peripheral edge portion 422 may be thinner than the axial thickness of the outer peripheral edge portion 422 . When the thickness of the disk portion 42 in the area on the inner diameter side of the outer peripheral edge portion 422 is made thinner than the outer peripheral edge portion 422, as shown in FIG. 425 may be provided. A plurality of rib portions 425 are radially formed from the first bearing accommodating portion 41 toward the annular projecting portion 43 . By providing the plurality of rib portions 425, the strength of the heat sink 4 can be ensured.

The axial positioning portion 420 is formed on the rear surface 424 side of the outer peripheral edge portion 422 and contacts the open end portion 101 of the resin outer shell 10 . As shown in FIG. 1, the axial positioning portion 420 abuts the open end portion 101 in the direction of the axis C. As shown in FIG. For example, the axial positioning portion 420 may be processed into a flat surface by a lathe or the like after the heat sink 4 is formed by die casting or the like. In this embodiment, the axial positioning portion 420 is formed on a plane perpendicular to the axis C. As shown in FIG.

As shown in FIG. 3A, the axial positioning portion 420 is formed by a plane perpendicular to the axis C over the entire rear surface 424 side of the outer peripheral edge portion 422, but this is not the only option. For example, the axial positioning portion 420 of the heat sink 4 may have an annular projection projecting toward the open end 101, and the open end 101 of the resin shell 10 has an annular projection corresponding to the projection. It may have grooves. A cross section of the protruding portion viewed from the radial direction may be trapezoidal or curved.

As shown in FIGS. 3A and 3B, holes 421 through which screws are inserted are formed at a plurality of locations on the outer peripheral edge portion 422 of the disc portion 42 . In this embodiment, three holes 421 are provided at equal angular intervals on the outer peripheral edge 422 . Note that the number and positions of the holes 421 provided in the outer peripheral edge portion 422 can be changed as appropriate, and the outer peripheral edge portion 422 need not be provided with the hole portions 421 . In this embodiment, the opening end 101 of the resin shell 10 is formed with the screw receiving portion 103 shown in FIG. The heat sink 4 is fixed to the open end 101 of the resin outer shell 10 with a plurality of screws inserted through the holes 421 . At this time, the heat sink 4 is positioned in the circumferential direction with respect to the open end portion 101 of the resin shell 10 .

The disc part 42 further has a notch part 426 formed over a predetermined angular range in a part of the outer peripheral edge part 422 thereof. The notch portion 426 is provided at a position corresponding to the above-described cable insertion portion formed over the vicinity of the open end portion 101 of the resin outer shell 10 . Accordingly, the notch 426 can be used as a mark for positioning the heat sink 4 in the resin shell 10 in the circumferential direction when the heat sink 4 is assembled to the open end 101 of the resin shell 10 .

(Annular protrusion)
As mentioned above, the annular projection 43 has a radial positioning portion 430 . In this embodiment, the radial positioning portion 430 is formed on the outer peripheral surface of the annular projecting portion 43 that contacts the inner peripheral surface of the open end portion 101 of the resin outer shell 10 . That is, as shown in FIGS. 1, 2, and 3A, the radial positioning portion 430 has a cylindrical surface that fits into the inner peripheral surface 10a of the resin outer shell 10. As shown in FIG.

As shown in FIG. 3(A), the annular projecting portion 43 is formed in an annular shape around the axis C on the rear surface 424 of the disc portion 42 . As shown in FIG. 1, the cross section parallel to the axis C of the annular protrusion 43 is generally rectangular. Further, as shown in FIG. 3A, the annular projecting portion 43 is continuously formed in the circumferential direction without any discontinuities, but this is not the only option, and a discontinuous portion may be provided.

(protrusion)
As described above, the projecting portion 44 is arranged on the inner diameter side of the annular projecting portion 43 and projects from the back surface 424 of the disk portion 42 toward the circuit board 5 side in the axial direction.

As shown in FIG. 3(A), in the present embodiment, the protrusion 44 is a rectangular parallelepiped block that protrudes toward the electronic component 51 mounted on the circuit board 5 . Furthermore, the protrusion 44 has a facing surface 441 that faces the electronic component 51 . In addition, the shape of the protrusion 44 is not limited to a rectangular parallelepiped shape, and may be, for example, a cylindrical shape.

Although details will be described later, as shown in FIG. 1, it is preferable that the projection height of the projection 44 in the axial direction be greater than the projection height of the annular projection 43 . The protruding height here is the height protruding in the axial direction with respect to the back surface 424 of the disc portion 42 . In the present embodiment, the facing surface 441 of the protrusion 44 is positioned closer to the circuit board 5 than the tip of the annular protrusion 43 in the axial direction. The protrusion height of the protrusion 44 is such that when the axial positioning portion 420 of the disc portion 42 abuts against the open end portion 101 of the resin shell 10 , the facing surface 441 of the protrusion 44 touches the upper surface of the electronic component 51 . It is set to form a gap with a size within a predetermined range.

The shape of the facing surface 441 viewed from the electronic component 51 side may be formed in accordance with the shape of the electronic component 51, and is, for example, a square plane (see FIG. 3A). The facing surface 441 may be processed into a flat surface by a lathe or the like after the heat sink 4 is formed by die casting or the like, for example.

A heat transfer member 52 and an adhesive member 53 are arranged in order from the electronic component 51 side between the electronic component 51 and the protrusion 44 . is in thermal contact with the electronic component 51 via the . The distance between facing surface 441 and electronic component 51 is set to be equal to or less than the total thickness of heat transfer member 52 and adhesive member 53 . Accordingly, the opposing surface 441 can be stably brought into contact with the upper surface of the electronic component 51 via the heat transfer member 52 and the adhesive member 53 . Alternatively, only the heat transfer member 52 or the adhesive member 53 may be arranged between the electronic component 51 and the protrusion 44 .

The heat transfer member 52 preferably has good thermal conductivity and high insulation, and for example, a heat dissipation sheet made of silicone resin is used. Similarly, the adhesive member 53 preferably has good thermal conductivity and high insulating properties, and for example, a silicon resin adhesive is used. The adhesive member 53 not only bonds the heat transfer member 52 and the protrusion 44 together, but also absorbs variations in axial position between the protrusion 44 and the electronic component 51 due to deformation of the adhesive member 53 . Further, the adhesive member 53 relieves the pressing force from the protrusion 44 to the electronic component 51 by deformation of the adhesive member 53 when the heat sink 4 is fitted to the resin shell 10 . As a result, stable thermal connection between the protrusion 44 and the electronic component 51 can be ensured, and the electronic component 51 and the circuit board 5 can be prevented from being damaged by the force applied from the protrusion 44 in the axial direction.

[Processing process of heat sink]
FIG. 4 is a schematic diagram showing a part of the processing steps of the heat sink 4 in this embodiment. In the present embodiment, in order to increase the dimensional accuracy in the direction of the axis C of the heat sink 4 formed by die casting (casting), as post-processing, the axial positioning portion 420 and the opposing surface 441 of the heat sink 4 are made flat. It is machined on a lathe. The heat sink 4 is first formed as a casting in a casting (die casting) process by solidifying a metal (alloy) poured into a mold (not shown). After that, the heat sink 4 is machined by lathe processing for the radial positioning portion 430 , the axial positioning portion 420 , and the facing surface 441 . In the present embodiment, a case is exemplified in which the heat sink 4 is machined in the order of the radial positioning portion 430, the axial positioning portion 420, and the facing surface 441 by a normal lathe (general-purpose lathe).

In lathe processing, the cast heat sink 4 is fixed to a headstock (not shown) (mechanism for rotating attached members) using a chuck (claw) not shown. As a result, the heat sink 4 rotates around the axis C. As shown in FIG. Next, by bringing a cutting tool B (cutting tool) fixed to the tool post into contact with the rotating heat sink 4 , the end surface of the heat sink 4 is shaved. At this time, by moving the cutting tool B in the radial direction of the axis C, a plane perpendicular to the axis C is formed. Further, by moving the cutting tool B parallel to the axis C, a cylindrical surface is formed.

FIG. 4(A) is a cross-sectional view showing the machining process of the radial positioning portion 430. FIG. That is, as shown in FIG. 4A, by moving the cutting tool B in parallel with the axis C, the radial positioning portion 430, which is the outer peripheral surface of the annular projecting portion 43, can be adjusted with high accuracy in its radial dimension. It is formed. At this time, since the radial positioning portion 430 is formed on the outer peripheral surface of the annular protrusion 43, when the tool B is brought closer to the lathe from the outer diameter side of the axis C, the annular protrusion 43 is machined. out of the way. Therefore, even if the heat sink 4 is formed by die casting (casting), when combining the resin outer shell 10 (not shown) and the heat sink 4, the outer peripheral surface (radial direction positioning portion 430) of the annular projecting portion 43 and the resin outer shell 10 can be brought into contact with the inner peripheral surface 10a (not shown) of 10 with high dimensional accuracy.

FIG. 4B is a cross-sectional view showing the process of machining the axial positioning portion 420 and the facing surface 441. As shown in FIG.
Further, as shown in FIG. 4(B), by moving the cutting tool B in the radial direction perpendicular to the axis C, the axial positioning portion 420 formed on the outer diameter side of the annular projecting portion 43 moves along the axis. Directional dimensions are formed with high accuracy. At this time, since the axial positioning portion 420 is formed on the outer peripheral side of the annular protrusion 43 described above, when the tool B is brought closer to the lathe from the outer diameter side of the axis C, the annular protrusion 43 does not interfere with processing. Therefore, even if the heat sink 4 is formed by die casting (casting), when combining the resin outer shell 10 (not shown) and the heat sink 4, the axial positioning portion 420 of the heat sink 4 and the open end portion 101 of the resin outer shell 10 are separated. (not shown) can be brought into contact with high dimensional accuracy.

Further, as shown in FIG. 4B, by moving the cutting tool B in the radial direction perpendicular to the axis C, the facing surface 441 of the protrusion 44 formed on the inner diameter side of the annular protrusion 43 is Axial dimensions are formed with high accuracy. At this time, although the facing surface 441 is formed on the inner peripheral side of the annular projecting portion 43 , the projecting height of the projecting portion 44 is formed to be higher than the projecting height of the annular projecting portion 43 . Also, when the cutting tool B is brought closer to the lathe from the outer diameter side of the axis C, the annular projecting portion 43 does not interfere with the machining. Therefore, even if the heat sink 4 is molded by die casting (casting), when the resin shell 10 (not shown) and the heat sink 4 are combined, the circuit board 5 fixed to the resin shell 10 and the protrusions 44 of the heat sink 4 are not in contact with each other. can be positioned with high dimensional accuracy.

[Action of heat sink]
As described above, the heat sink 4 of this embodiment includes the axial positioning portion 420 that contacts the open end portion 101 of the resin outer shell 10 and the radial positioning portion that contacts the inner peripheral surface of the open end portion 101 of the resin outer shell 10 . 430. Therefore, at the same time as the heat sink 4 is assembled to the resin outer shell 10 , the heat sink 4 is positioned in both the axial direction and the radial direction with respect to the resin outer shell 10 .

More specifically, the heat sink 4, which is an integrated component, is provided with an axial positioning portion 420 for positioning the relative position of the heat sink 4 in the axial direction with respect to the resin outer shell 10, and the heat sink 4 with respect to the electronic component 51 of the circuit board 5. A facing surface 441 of the protrusion 44 is provided for positioning the relative axial position of the . Therefore, the accuracy of the relative position of the heat sink 4 in the axial direction with respect to the resin shell 10 is ensured. As a result, variations in the axial relative positions (dimensional variations and assembly variations) between the facing surfaces 441 of the projections 44 and the electronic components 51 are suppressed, and heat is stably transferred from the electronic components 51 to the heat sink 4 . can sufficiently dissipate heat to the outside of the

In addition, since the heat sink 4 is formed with the radial positioning portion 430 , it is possible to reduce radial assembly variations between the heat sink 4 and the resin outer shell 10 . It is possible to accurately face the electronic component 51 on the circuit board 5 fixed to the shaft in the axial direction. Further, the first bearing 71 can be arranged coaxially with the axis C with high accuracy.

Therefore, according to this embodiment, there is no need for a separate supporting member for positioning between the heat sink 4 and the open end 101 of the resin shell 10 (for example, the metal bracket described in Patent Document 1). A heat sink 4 can be assembled directly to the shell 10 . As a result, the number of parts can be reduced and assembly workability can be improved compared to the case where the heat radiation fins are fixed to the ends of the resin shell via metal brackets that support the bearings, as described in Patent Document 1, for example. In addition, it is possible to improve the positioning accuracy of the heat sink with respect to the resin shell.

That is, when another member such as the metal bracket is interposed between the resin shell and the heat sink (radiating fin), the thickness variation of the metal bracket and the heat sink itself, the processing size variation, and the assembly variation of the resin shell and the metal bracket Influenced by various variations such as variations in assembly of the metal bracket and the heat sink, variation in relative position between the heat sink and the resin shell in the axial and radial directions is likely to occur. For this reason, there is a possibility that the desired heat transfer characteristics cannot be stably ensured due to variations in the desired distance between the circuit board and the protrusion of the heat sink.

In contrast, according to the present embodiment, the heat sink 4 is directly attached to the open end portion 101 of the resin shell 10 without interposing the metal bracket. The protrusion 44 of the heat sink 4 can be positioned with high precision with respect to the circuit board 5 (electronic component 51). As a result, variations in the distance between the facing surface 441 of the protrusion 44 of the heat sink 4 and the electronic component 51 of the circuit board 5 can be suppressed. Therefore, the distance between the projecting portion 44 (opposing surface 441) and the circuit board 5 (electronic component 51) becomes larger than necessary (for example, the distance between the opposing surface 441 and the electronic component 51 is greater than the thickness of the heat transfer member 52). and the thickness of the adhesive member 53), and it is possible to prevent the heat transfer from the electronic component 51 to the heat sink 4 from being hindered and stable heat dissipation to be impossible. Furthermore, it is possible to prevent the distance between the facing surface 441 and the electronic component 51 from becoming smaller than necessary, and to prevent the electronic component 51 and the circuit board 5 from being damaged by the force applied from the protrusion 44 in the axial direction.

Also, according to this embodiment, the heat sink 4 includes the bearing housing portion 41, so that the first bearing 71 can be supported without the need for the metal bracket. As a result, the number of parts can be reduced and the assembling workability of the electric motor 1 can be improved.

Further, according to the present embodiment, when the heat sink 4 is formed by die-casting with large dimensional variations, the axial positioning portion 420 and the opposing surface 441 are end-faced in a post-process using a lathe, so that the heat sink 4 dimensional variation in the axial direction can be reduced. Therefore, variation in the axial relative position (assembly variation) between the facing surface 441 of the protrusion 44 and the electronic component 51 is further suppressed, and heat is stably transferred from the electronic component 51 to the heat sink 4, thereby can sufficiently dissipate heat to

<Second embodiment>
FIG. 5 is a schematic cross-sectional view of essential parts of an electric motor 1A according to a second embodiment of the invention. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

As shown in FIG. 5, the electric motor 1A of this embodiment includes a heat sink 4A having a disk portion 42A, an annular projecting portion 43A, and a projecting portion 44. As shown in FIG. The heat sink 4A of this embodiment differs from that of the first embodiment in that the annular projecting portion 43A is located outside the open end portion 101 of the resin outer shell 10 .

In this embodiment, the disk portion 42A has an outer diameter larger than the outer diameter of the open end portion 101 of the resin outer shell 10. The disk portion 42A has an axial positioning portion 420A on its rear surface 424 side, which contacts the open end portion 101 of the resin outer shell 10 . The axial positioning portion 420A is formed of a plane perpendicular to the axis C, as in the first embodiment.

The annular projecting portion 43A is formed on the rear surface 424 side of the disk portion 42A so as to protrude in the axial direction from the outer peripheral edge portion 427 of the disk portion 42A. In this embodiment, the outer peripheral edge portion 427 is a region of the disk portion 42A on the outer peripheral side of the axial positioning portion 420A. The radial positioning portion 430A is formed on the inner peripheral surface of the annular projecting portion 43A and contacts the outer peripheral surface of the resin outer shell 10 .

The heat sink 4A of this embodiment configured as described above includes an axial positioning portion 420A that contacts the open end portion 101 of the resin outer shell 10, and a radial positioning portion 420A that contacts the outer peripheral surface of the open end portion 101 of the resin outer shell 10. It has a part 430 . Therefore, as in the first embodiment, the heat sink 4A is positioned both in the axial direction and the radial direction with respect to the resin outer shell 10 at the same time as the heat sink 4A is attached to the resin outer shell 10. FIG. As a result, the projections 44 of the heat sink 4A can be positioned with high accuracy with respect to the circuit board 5 (electronic components 51), so that good heat transfer can be achieved between the heat sink 4A and the circuit board 5 (electronic components 51). characteristics can be secured.

<Modification>
In each of the embodiments described above, the case where the

heat sink

4, 4A has one protrusion 44 has been described. For example, if there are two or more electronic components with different heights, a plurality of projections corresponding to the respective heights may be provided. may be formed so as to protrude into the two electronic components at .

Further, in the above-described embodiment, a load (torque) is provided at one end of the shaft 6 of the electric motor 1, and a single-shaft motor that produces an output in response to the load has been described as an example. A dual-shaft motor may be used in which a load (torque) is provided to the motor and the output is generated in response to the load.

Also, in the present embodiment described above, the circuit board 5 has a disk shape along the inner peripheral surface 10a of the resin outer shell 10, but it is of course not limited to this. It may have any shape as long as it can be supported on the mounting surface 9, and may be rectangular, for example.

Furthermore, in the above embodiment, the rotor main body 30 has a three-part structure consisting of the outer core 32, the insulating member 33, and the inner core 34. However, it is not limited to this, and may be composed of a single core member. good too.

Further, the rotor 3 is not limited to the surface magnet type as in the embodiment, but may be an embedded magnet type in which a plurality of magnet embedding holes for embedding permanent magnets are formed in the rotor main body 30 (rotor core). good too.

DESCRIPTION OF SYMBOLS 1, 1A...

Electric motor

4, 4A... Heat sink 10... Resin shell 101... Opening end part 2... Stator 21... Stator iron core 3... Rotor 31... Permanent magnet part 32... Outer circumference side iron core 33... Insulating member 34... Inner circumference Side iron core 4 Heat sink 41 First

bearing accommodating portion

42,

42A Disk portion

43, 43A Annular projection 44

Projection

420, 420A

Axial positioning portion

430, 430A Annular projection 5 Circuit board 51... Electronic component 6... Rotary shaft C... Axis center

Claims

A cylindrical resin shell having an open end at one end in the axial direction, a stator core formed integrally with the resin shell, a rotor disposed on the inner diameter side of the stator core, and the resin a heat sink covering the open end of the outer shell; and a circuit board arranged in an internal space covered with the resin outer shell and the heat sink,
The heat sink
a disk portion;
an annular projecting portion projecting from the disk portion toward the circuit board in the axial direction;
a protruding portion disposed on the inner diameter side of the resin outer shell relative to the annular protruding portion, protruding from the disk portion toward the circuit board side and in thermal contact with the circuit board;
has
The disk portion has an axial positioning portion that contacts the open end portion of the resin outer shell,
The said annular protrusion part has a radial direction positioning part contact|abutted to the inner peripheral surface or outer peripheral surface of the said resin outer shell. Electric motor.
The electric motor according to claim 1,
The radial positioning portion is formed on the outer peripheral surface of the annular projecting portion and is in contact with the inner peripheral surface of the resin outer shell.
The electric motor according to claim 1 or 2,
The axial positioning portion is located on the outer peripheral side of the annular projecting portion of the disk portion.
The electric motor according to any one of claims 1 to 3,
The projection height in the axial direction of the projection is greater than the projection height of the annular projection.
The electric motor according to any one of claims 1 to 4,
The circuit board includes electronic components that generate heat when energized,
The electric motor, wherein the protrusion has a facing surface facing the electronic component.
The electric motor according to any one of claims 1 to 5,
The electric motor, wherein the resin shell has a mounting surface to which the circuit board is fixed.
The electric motor according to any one of claims 1 to 6,
The electric motor has a rotating shaft to which the rotor is fixed, and a first bearing that rotatably supports the rotating shaft,
The electric motor, wherein the heat sink further includes a bearing accommodating portion that accommodates the first bearing.
A method for manufacturing an electric motor according to any one of claims 2 to 4,
The method of manufacturing an electric motor, wherein the heat sink is formed by die casting.