JP7725916B2 - electric motor - Google Patents

Description

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

Conventionally, electric motors have been known that have a circuit board inside them that controls the rotational drive of the motor. These circuit boards contain electronic components that generate heat when current is passed through them, and electric motors that have a heat sink that dissipates the heat generated by these electronic components to the outside of the motor are also known.

For example, Patent Document 1 describes a brushless motor equipped with a control board, an IPM (electronic component) that serves as an inverter, and a heat transfer member, in which the heat transfer member forms a path for dissipating heat generated by the IPM mounted on the control board when current is applied to the IPM, to the outside of the brushless motor case.

Patent Document 2 also describes a brushless motor that includes a steel plate bracket that holds a bearing and houses and secures a stator; a circuit board that is placed within the steel plate bracket and that has a heat-generating component (electronic component) mounted thereon; a heat-transfer component that is placed between the steel plate bracket and the heat-generating component and transfers heat generated by the heat-generating component to the steel plate bracket; and a fixing member for fixing the heat-transfer component onto the heat-generating component.

JP 2012-80653 A JP 2015-192544 A

In Patent Document 1, the heat transfer member is placed on an IPM, which is an electronic component that generates heat when current is applied. However, part of the underside of the heat transfer member is not supported by the electronic component, which creates the risk that the heat transfer member will be fixed at an angle relative to the electronic component when the motor is assembled. This results in a problem of reduced heat transfer and insulation between the electronic component and the heat transfer member.

On the other hand, in Patent Document 2, the fixing member is composed of an engagement portion that secures the electronic component and a heat transfer component holder that is fitted into the heat transfer component, which creates the problem of a complicated assembly process when connecting the heat transfer component holder to the engagement portion. Furthermore, because the fixing member is formed to fit the size of the heat transfer component, if the size of the heat transfer component is changed, the fixing member also needs to be reshaped to fit the size of the heat transfer component.

In light of the above circumstances, the object of the present invention is to provide an electric motor that prevents the heat transfer member from being fixed at an angle relative to the electronic components inside the electric motor, while minimizing the complexity of the assembly process.

To achieve the above object, one embodiment of the present invention provides an electric motor comprising: a rotor having a rotating shaft; a stator arranged on the outer diameter side of the rotor; a housing case that houses the stator; a circuit board arranged in the internal space covered by the housing case; and a heat transfer member that forms a heat transfer path between the circuit board and the housing case; electronic components and a support member are arranged on the circuit board; and the heat transfer member is supported by the electronic components and the support member.

In the above-described electric motor, the heat transfer member is supported by the electronic components arranged on the circuit board and the support member. This allows the heat transfer member to be supported more stably than if the heat transfer member were supported only by the electronic components, and prevents the heat transfer member from being fixed at an angle relative to the electronic components during assembly.

The electronic component may have a first support surface that supports the heat transfer member, and the support member may have a second support surface that supports the heat transfer member together with the first support surface.

The second support surface may be formed in a position that does not overlap with the first support surface when viewed in a direction perpendicular to the circuit board.

The second support surface may be positioned on the outer diameter side of the first support surface.

The electronic component may have a main body and lead portions extending from the main body, and the support member may have an outer frame portion surrounding the outer periphery of the electronic component.

The outer frame portion may have a restricting portion that restricts the range of resin applied to the lead portion, and the restricting portion may be formed in a position that does not overlap with the second support surface when viewed from a direction perpendicular to the circuit board.

The height of the second support surface from the circuit board may be greater than the height of the restricting portion.

The outer frame portion may have a locking portion that abuts against the surface of the main body portion on which the lead portion is formed.

This invention provides an electric motor that prevents the heat transfer member from being fixed at an angle relative to the electronic components inside the motor, while minimizing the complexity of the assembly process.

1 is a partial cross-sectional view of an electric motor according to an embodiment of the present invention. 1 is a cross-sectional view of a main part of an electric motor according to an embodiment of the present invention. 1A and 1B are diagrams showing a support member of an electric motor according to an embodiment of the present invention, in which FIG. 1A is a top view of the support member, and FIG. 1B is a side cross-sectional view of the support member. 1A and 1B are diagrams showing a support member of an electric motor according to an embodiment of the present invention, in which FIG. 1A is a top perspective view of the support member, and FIG. 1B is a bottom perspective view of the support member. FIG. 10 is a cross-sectional view of a main part of a comparative example electric motor that does not have a support member.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, identical or similar parts are designated by identical or similar reference numerals. However, it should be noted that the drawings are schematic and may differ from the actual product. Therefore, specific component parts should be determined in light of the following description.

Furthermore, the embodiments shown below are merely examples of devices and methods that embody the technical concept of the present invention, and the technical concept of the present invention does not limit the shape, structure, arrangement, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

Figure 1 is a partial cross-sectional view of an electric motor 1 according to an embodiment. The electric motor 1 of this embodiment is used, for example, as a drive source for a blower fan mounted in the indoor unit of an air conditioner.

[Overall configuration of the electric motor]
The electric motor 1 includes a stator 2 (stator core 21 ), a rotor 3 , a housing case 10 , a support member 4 , and a base plate portion 5 .

In the following, as an example, the electric motor 1 will be described as an inner rotor brushless DC motor in which a cylindrical rotor 3 having a permanent magnet portion 32 is rotatably arranged radially inside a cylindrical stator 2 that generates a rotating magnetic field. However, the electric motor is not limited to this, and may be other electric motors such as an outer rotor brushless DC motor or an AC motor.

In the following description, the axis C of the rotating shaft 6 is also the central axis of the electric motor 1, i.e., the rotation axis of the rotor 3. The radial direction is the direction that passes through the axis C and is perpendicular to the axial direction. The inner diameter side is the inside in the radial direction, and the outer diameter side is the outside in the radial direction. Furthermore, the circumferential direction is the direction of rotation around the axis C.

(rotor)
The rotor 3 has a rotor body 31, a permanent magnet portion 32, and a rotating shaft 6. The rotor body 31 is a laminate of plates made of a soft magnetic material, such as a plurality of electromagnetic steel sheets. The permanent magnet portion 32 is fixed in an annular shape to the outer circumferential surface of the rotor body 31, and the rotating shaft 6 is fixed to the inner circumferential surface of the rotor body 31 by press-fitting, caulking, or the like. This causes the rotating shaft 6 to rotate integrally with the rotor body 31.

The rotor 3 is a surface magnet type in which a permanent magnet portion 32 is fixed in an annular shape to the outer circumferential surface. The permanent magnet portion 32 is formed in an annular shape from multiple permanent magnets (e.g., 8 or 10 pieces) so that north and south poles alternate in the circumferential direction. The permanent magnet portion 32 is typically formed from a sintered metal such as an Nd-Fe-B alloy, but may also be a plastic magnet formed in an annular shape by solidifying magnetic powder with resin. The permanent magnet portion 32 is not limited to a surface magnet type in which a permanent magnet is fixed to the outer circumferential surface of the rotor body 31; for example, it may be an embedded magnet type in which multiple plate-shaped permanent magnets are embedded in the rotor body 31.

(stator)
The stator 2 includes a stator core 21, coils 22, and insulators 23. The stator core 21 is a laminate of plates made of a soft magnetic material, such as electromagnetic steel sheets. The stator core 21 includes an annular yoke and a plurality of teeth protruding inward from the yoke. A coil 22 is wound around each tooth of the stator core 21 via an insulator 23. The plurality of coils 22 includes coils corresponding to three phases: U, V, and W. These coils are connected to each other, for example, at an electrical neutral point (point N). The outer peripheral surface of the stator 2 (stator core 21) is covered by a housing case 10 (see FIG. 1). The stator core 21 of the stator 2 is disposed radially opposite the permanent magnet portion 32 of the rotor 3 with a gap (magnetic gap) between them.

(Storage case)
The housing case 10 holds a first bearing 71 and a second bearing 81 (described below) that support the rotating shaft 6, and houses and fixes the stator 2. The housing case 10 has a first housing case 11 and a second housing case 12 that are divided in the axial direction of the rotating shaft 6. The first housing case 11 is provided on the output end 61 side of the rotating shaft 6, and the second housing case 12 is provided on the anti-output end 62 side of the rotating shaft 6. The first housing case 11 on the output end 61 side is formed in a cylindrical shape with a bottom and has a flange 111 at the end on the opening side of the first housing case 11. A portion of the stator 2 is inserted into this first housing case 11 along the axial direction of the rotating shaft 6. A first bearing accommodating portion 113 (described later) having a cylindrical shape with a bottom and a smaller diameter than the bottom surface 112 and protruding toward the output end portion 61 in the axial direction is formed in the center of the bottom surface 112 of the first accommodating case 11, and the first bearing 71 is held in the first bearing accommodating portion 113.

The second housing case 12 on the anti-output end 62 side is formed in a cylindrical shape with a bottom, similar to the first housing case 11, and has a flange 121 at the open end of the second housing case 12. This second housing case 12 is positioned to cover the remaining portion of the stator 2 and the circuit board 51 located on the anti-output end 62 side in the axial direction of the rotating shaft 6 of the stator 2, and the flange 121 of the second housing case 12 is fastened to the flange 111 of the first housing case 11 with fastening members 14. A second bearing housing 123 (see Figure 2) is formed in the center of the bottom surface 122 of the second housing case 12. The second bearing 81 is cylindrical and has a smaller diameter than the bottom surface 122 and protrudes toward the anti-output end 62 in the axial direction.

The first storage case 11 and the second storage case 12 are formed, for example, by pressing a metal plate.

(bearings)
1, the first bearing 71 is a ball bearing including an outer ring 711, an inner ring 712, and a plurality of balls 713. The second bearing 81 is a ball bearing including an outer ring 811, an inner ring 812, and balls 813.

The outer ring 711 of the first bearing 71 is fixed to the first housing case 11 (first bearing housing portion 113), and the inner ring 712 of the first bearing 71 is fixed to the output end 61 side of the rotating shaft 6. The outer ring 813 of the second bearing 81 is fixed to the second housing case 12 (second bearing housing portion 123), and the inner ring 812 of the second bearing 81 is fixed to the non-output end 62 side of the rotating shaft 6. As a result, the rotating shaft 6 is supported by the first bearing 71 and the second bearing 81 so as to be rotatable around the axis C relative to the housing case 10.

Figure 2 is a cross-sectional view of a main portion of an electric motor 1 according to an embodiment of the present invention.

(Bearing accommodating portion)
1, the first bearing accommodating portion 113 accommodates the first bearing 71. The first bearing accommodating portion 113 has a generally cylindrical shape centered on the axis C, and accommodates the first bearing 71 therein.
The second bearing accommodating portion 123 accommodates the second bearing 81. The second bearing accommodating portion 123 has a generally cylindrical shape centered on the axis C, and accommodates the second bearing 81 therein.
2, the second bearing accommodating portion 123 is formed by pressing the accommodating case 10. As a result of forming the second bearing accommodating portion 123 by pressing, the second accommodating case 12 has a recess 124 provided so as to surround the outer periphery of the second bearing accommodating portion 123. The recess 124 is formed such that the bottom surface 122 of the second accommodating case 12 is recessed in an annular shape toward the output end portion 61.

Figure 3 also shows the support member 4 of the electric motor 1 according to an embodiment of the present invention, where (A) is a top view of the support member 4 and (B) is a cross-sectional side view of the support member 4.

(Substrate part)
As shown in FIG. 2 , the substrate unit 5 includes a circuit board 51, electronic components 52 that generate heat when current is applied and are mounted on the surface of the circuit board 51 (the surface opposite the output end 62 of the rotating shaft 6), and lead portions 522 mounted on the surface of the circuit board 51. The circuit board 51 has a central hole 50 through which the rotating shaft 6 passes and is formed in a generally circular plate shape. The circuit board 51 is supported on a board support base (not shown) provided within the housing case 10. The circuit board 51 is electrically connected to the ends 24 of the coils 22. The circuit board 51 is electrically connected to the ends 221 of the coils 22, thereby electrically connecting the electronic components 52 and the coils 22, and enabling a drive signal output from the electronic components 52 to be supplied to the coils 22.

The electronic component 52 is disposed on the circuit board 51 and has an upper surface 523 as a first support surface that supports the heat transfer member 91 (described later) (see Figure 3). The electronic component 52 also has a main body 521 having the upper surface 523, and lead portions 522 formed on the outer periphery of the main body 521.

As shown in Figure 3, the main body 521 is a package made of synthetic resin that incorporates a semiconductor element, and the lead portions 522 are multiple metal external terminals that electrically connect the semiconductor element to the circuit board 51.
The upper surface portion 523 is the upper surface side (the surface opposite to the output end portion 62) of the main body portion 521. When the electronic components 52 are mounted on the circuit board 51, the upper surface portion 523 is approximately parallel to the circuit board 51 and supports the heat transfer member 91.
The lead portion 522 is provided on one side surface 524 that forms the outer periphery of the main body portion 521 .

The electronic components 52 that generate heat when current is applied are primarily semiconductor components such as power supply ICs and ICs for controlling motor drive current, but may also include passive components such as capacitors. In addition to the electronic components 52, the circuit board 51 also carries other components such as a connector component 53 that connects to a power cable (not shown). The power cable is connected to a power source (not shown) through a cable insertion portion 13 (see Figure 1) formed in part of the housing case 10.

(Heat transfer member)
3A and 3B form a heat transfer path between the circuit board 51 on which the electronic components 52 are arranged and the housing case 10. The heat transfer member 91 is a block-shaped component made of a metal material with high thermal conductivity, such as aluminum or copper. The heat transfer member 91 transfers heat from the electronic components 52 transferred from the heat dissipation sheet 92 to the adhesive member 93, and dissipates the heat from the second housing case 12 to the outside (outside the electric motor 1). As shown in FIG. 3B, the adhesive member 93 is a heat-conductive adhesive that bonds the top surface 911 of the heat transfer member 91 to the bottom surface 122 of the second housing case 12, and transfers the heat transferred from the heat transfer member 91 to the housing case 10.
As shown in FIG. 3A, the area of the heat transfer member 91 when viewed in a direction perpendicular to the circuit board 51 is preferably larger than the area of the upper surface 523 of the electronic component 52.

As shown in FIG. 3(B), the heat dissipation sheet 92 transfers heat generated by the electronic components 52 to the underside 912 of the heat transfer member 91. The heat dissipation sheet 92 is a flexible, adhesive, rectangular heat transfer member made of a material such as silicone.

The heat dissipation sheet 92 has a larger area than the heat transfer member 91 when viewed perpendicular to the circuit board 51 (in the direction of the rotational axis of the electric motor 1). This allows the insulating heat dissipation sheet 92 to be placed across the entire opposing surfaces of the electronic component 52 and heat transfer member 91, ensuring electrical insulation between the electronic component 52 and heat transfer member 91.

Furthermore, because the heat dissipation sheet 92 has a larger area than the heat transfer member 91 when viewed perpendicular to the circuit board 51 (the direction of the rotational axis of the electric motor 1), the heat generated by the electronic components 52 can be transferred to the heat transfer member 91 more efficiently than when the heat dissipation sheet 92 has a smaller area than the heat transfer member 91.

Furthermore, when the first housing case 11 and the second housing case 12 are fitted together, the heat dissipation sheet 92 comes into close contact with both the heat transfer member 91 and the electronic component 52, and at the same time, the force pressing the heat transfer member 91 against the electronic component 52 is released by the deformation of the heat dissipation sheet 92. This ensures a stable thermal connection between the heat transfer member 91 and the electronic component 52, improving heat transfer, and also prevents damage to the electronic component 52 or circuit board 51 due to the force applied axially from the heat transfer member 91.

The adhesive member 93 not only bonds the casing 10 and the heat transfer member 91 together, but also absorbs variations in the axial positions of the casing 10 and the heat transfer member 91 due to deformation of the adhesive member 93 before solidification.
Furthermore, when the first housing case 11 and the second housing case 12 are fitted together, the adhesive member 93 adheres the housing case 10 and the heat transfer member 91 together, and at the same time, the adhesive member 93 dissipates the pressing force from the housing case 10 to the heat transfer member 91 by deforming the adhesive member 93. This ensures a stable thermal connection between the housing case 10 and the heat transfer member 91, improving heat transfer, and also prevents the electronic components 52 and the circuit board 51 from being damaged by the force applied in the axial direction from the housing case 10.

Figure 4 shows the support member 4 of the electric motor 1 according to an embodiment of the present invention, where (A) is a top perspective view of the support member 4 and (B) is a bottom perspective view of the support member 4.

(Support member)
3A and 3B, the support member 4 is disposed on the circuit board 51. The support member 4 has a support surface portion 41 (second support surface) that supports the heat transfer member 91. The support surface portion 41 (second support surface) of the support member 4 supports the heat transfer member 91 together with the upper surface portion 523 (first support surface) of the electronic component 52. In other words, the heat transfer member 91 is supported by the upper surface portion 523 (first support surface) of the electronic component and the support surface portion 41 (second support surface) of the support member 4. The support member 4 of this embodiment is approximately rectangular.

The support member 4 is, for example, an injection-molded synthetic resin such as PBT (polybutylene terephthalate). Furthermore, the support member 4 can ensure physical strength and heat resistance by mixing glass filler into the synthetic resin.

The support member 4 has an outer frame portion 40 that surrounds the outer periphery of the electronic component 52 (see Figure 3(A)). Furthermore, the outer frame portion 40 has a first frame portion 401, a second frame portion 402, a third frame portion 403, and a fourth frame portion 404, and inside the outer frame portion 40, a space portion 400 is formed by the above four frame portions, which surround the electronic component 52 (see Figure 4).

As shown in FIG. 4, the outer frame portion 40 is rectangular, with the first frame portion 401 and the third frame portion 403 corresponding to the long sides and the second frame portion 402 and the fourth frame portion 404 corresponding to the short sides. Also, as shown in FIG. 3, the first frame portion 401 and the third frame portion 403 face each other on the two long sides of the outer periphery of the electronic component 52, and the third frame portion 403 and the fourth frame portion 404 face each other on the remaining two short sides.

The support member 4 has multiple support base portions 410 formed to protrude outward from the first frame portion 401 of the outer frame portion 40 (see FIG. 4). Each support base portion 410 is roughly rectangular and has a support surface portion 41 on the heat transfer member 91 side that supports the heat transfer member 91. The height of the support surface portion 41 from the top surface of the circuit board 51 (second height H2) is roughly equal to the height of the top surface portion 523 of the electronic component 52 from the top surface of the circuit board 51 (i.e., the thickness of the electronic component 52). In this embodiment, the height of the support surface portion 41 from the top surface of the circuit board 51 is slightly lower than the height of the top surface portion of the electronic component 52 from the top surface of the circuit board 51. Furthermore, the bottom surface 912 of the heat transfer member 91 supported by the top surface portion 523 and support surface portion 41 is parallel to the circuit board 51.

Also, as shown in FIG. 3(A), the support surface portion 41 (second support surface) of the support member 4 is located so as not to overlap the upper surface portion 523 (first support surface) of the electronic component 52 when viewed from a direction perpendicular to the circuit board 51 (the direction of the rotational axis of the electric motor 1). Furthermore, the support base portion 410 having the support surface portion 41 is preferably located symmetrically with respect to the center of the length of the first frame portion 401. This allows for stable support of the heat transfer member 91.

4A and 4B, the support base 410 having the support surface 41 is divided into four parts along the length of the first frame 401. This makes it possible to prevent sink marks (depressions caused by volumetric shrinkage after molding) from occurring in the support surface 41, compared to when support bases having a length equivalent to a plurality of parts are integrally provided along the first frame 401, and therefore prevents a decrease in the dimensional accuracy of the support surface 41 in the height direction.
In addition, a hole 411 is formed in the center of each support base portion 410, penetrating the support base portion 410 in the height direction, as a recessed portion to further suppress a decrease in the dimensional accuracy of the support surface portion 41 in the height direction due to sink marks.

The support member 4 is positioned corresponding to the mounting position of the electronic component 52 on the circuit board 51, with the outer frame portion 40 surrounding the outer periphery of the electronic component 52. In this embodiment, the support surface portion 41 (second support surface) of the support member 4 is positioned radially outward from the top surface portion 523 (first support surface) of the electronic component 52. Also, as shown in FIG. 2, the support surface portion 41 of the support member 4 is positioned radially outward from the recess 124 formed in the second housing case 12.

As shown in FIG. 3(B), the outer frame portion 40 has a restricting portion 42 that faces the lead portion 522 of the electronic component 52. The restricting portion 42 restricts the application range of the resin W that is applied to the lead portion 522. In this embodiment, the third frame portion 403, a non-contact surface forming portion 463 of the second frame portion 402 (described below), and a non-contact surface forming portion 464 of the fourth frame portion 404 (described below) function as the restricting portion 42. The restricting portion 42 is formed so that a small gap is formed between the restricting portion 42 and the lead portion 522 when the support member 4 is placed on the circuit board 51. Furthermore, the restricting portion 42 is formed in a position that is not adjacent to the support base portion 410 having the support surface portion 41.

Also, as shown in Figures 3 and 4, the second height H2, which is the height of the support surface portion 41 from the circuit board 51, is formed to be higher than the first height H1, which is the height of the restriction portion 42 from the circuit board 51.

The second frame portion 402 has, on its surface facing the electronic component 52, a contact surface 451 that contacts one side surface of the short side of the main body portion 521 of the electronic component 52, and a non-contact surface 461 that does not contact the one side surface. The second frame portion 402 has a contact surface forming portion 453 on which the contact surface 451 is formed, and a non-contact surface forming portion 463 on which the non-contact surface 461 is formed. The fourth frame portion 404 has, on its surface facing the electronic component 52, a contact surface 452 that contacts the other side surface of the short side of the main body portion 521 of the electronic component 52, and a non-contact surface 462 that does not contact the other surface. The fourth frame portion 404 has a contact surface forming portion 454 on which the contact surface 452 is formed, and a non-contact surface forming portion 464 on which the non-contact surface 462 is formed.

The abutment surface forming portion 454 has an abutment upper surface portion 471 formed on the same plane as the support surface portion 41, and an inclined portion 472 formed between the abutment upper surface portion 471 and the non-abutment surface forming portion 464, which have different heights from the circuit board 51. The abutment upper surface portion 471 may be molded integrally with the support surface portion 41, as shown in FIG. 4(A). The abutment inclined portion 472 is formed at an acute angle from the non-abutment surface forming portion 464 toward the abutment upper surface portion 471, but is not limited to this and may be formed at a right angle. Also, although not shown, the abutment surface forming portion 453, like the abutment surface forming portion 454, has the abutment upper surface portion 471 and an inclined portion 472 connecting the abutment upper surface portion 471 and the non-abutment surface forming portion 463.

In this embodiment, when the support member 4 is placed on the circuit board 51, the height of the abutment surface forming portion 453 (abutment upper surface portion 471) of the second frame portion 402 from the circuit board 51 and the height of the abutment surface forming portion 454 (abutment upper surface portion 471) of the fourth frame portion 404 from the circuit board 51 are both the same height as the second height H2, which is the height of the support surface portion 41. In other words, the abutment surface forming portion 453 of the second frame portion 402 and the abutment surface forming portion 454 of the fourth frame portion 404, together with the support surface portion 41 formed on the first frame portion 401, support the heat transfer member 91.

Furthermore, the restricting portion 42 is formed so that when the support member 4 is placed on the circuit board 51, its height from the circuit board 51 is a first height H1. Specifically, the height of the third frame portion 403 from the circuit board 51, the height of the non-contact surface forming portion 463 of the second frame portion 402 from the circuit board 51, and the height of the non-contact surface forming portion 464 of the fourth frame portion 404 from the circuit board 51 are all set to the first height H1. The non-contact surface forming portion 463 of the second frame portion 402, the non-contact surface forming portion 464 of the fourth frame portion 404, and the third frame portion 403 all function as restricting portions 42 that restrict the application range of the resin W applied to the lead portions 522.

Here, it is preferable that the first height H1 of the restricting portion 42 is greater than the height of the lead portion 522. By making the first height H1 of the restricting portion 42 greater than the height of the lead portion 522, the lead portion 522 can be sufficiently coated with the resin W, even if the resin W does not exceed the first height H1 of the restricting portion 42, and insulation can be ensured. The applied height of the resin W is equal to or greater than the height that can cover the lead portion 522, and is set to be equal to or less than the first height H1 here.

The outer frame portion 40 has locking portions 43 that abut against the side surfaces 524 of the main body portion 521 on which the lead portions 522 are formed. In this embodiment, as shown in Figures 3(B) and 4(A) and (B), the locking portions 43 are provided on the inside of the outer frame portion 40 and are formed as protrusions that protrude inward. The locking portions 43 are provided on the second frame portion 402 and the fourth frame portion 404. By the locking portions 43 abutting against the side surfaces 524 of the main body portion 521 on which the lead portions 522 are formed, the distance between the third frame portion 403 of the outer frame portion 40 and the lead portions 522 of the electronic component 52 is maintained, and an appropriate area can be secured for application of the resin W.

The position where the locking portion 43 abuts against the side surface 524 of the main body portion 521 will be described in more detail. As shown in Figure 3(B), the locking portion 43 is located below the lead portion 522 extending from the side surface 524 of the main body portion 521. The locking portion 43 is formed in a tapered shape such that the protruding height gradually increases from the circuit board 51 toward the heat transfer member 91. Therefore, when the electronic component 52 is placed on the circuit board 51 and the support member 4 is attached from above, the locking portion 43 can be positioned so that it is recessed below the lead portion 522 while reducing the load on the lead portion 522, allowing the locking portion 43 to abut against the side surface 524 of the main body portion 521.

As shown in FIG. 4(A), the support member 4 has a protrusion 44 on the fourth frame portion 404. The protrusion 44 is provided so as to protrude from the fourth frame portion 404 toward the outside of the outer frame portion 40. The protrusion 44 functions as an incorrect installation prevention feature that prevents the support member 4 from being installed in the wrong orientation on the electronic component 52. For example, if the orientation in which the support member 4 is to be installed is different from the actual intended orientation (for example, the support member 4 is upside down), the protrusion 44 comes into contact with other electronic components (e.g., a capacitor) on the circuit board 51, preventing the support member 4 from being installed in the wrong orientation.

[Motor Action]
According to the electric motor 1, the electronic component 52 and the support member 4 are arranged on the circuit board 51, and the heat transfer member 91 is supported by the upper surface portion 523 (first support surface) of the electronic component 52 and the support surface portion 41 (second support surface) of the support member 4. This allows the heat transfer member 91 to be stably supported, and prevents the heat transfer member 91 from being fixed in an inclined state with respect to the electronic component 52 during assembly.

For example, in the comparative electric motor 1A shown in Figure 5, which does not have the support member 4, the heat transfer member 91A is positioned offset relative to the electronic component 52A, resulting in an area on one end of the underside of the heat transfer member 91A that is not supported by the electronic component 52A. As a result, in the comparative electric motor 1A, as shown in the area enclosed by circle A, the support for the heat transfer member 91A and the heat dissipation sheet 92A becomes unstable, causing the heat transfer member 91A and the heat dissipation sheet 92A to tilt relative to the circuit board 51A and potentially come into contact with the circuit board 51A (the dashed-dotted line indicates the tilted state of the heat transfer member 91A and the heat dissipation sheet 92A). In this case, if the heat transfer member 91A remains tilted, it becomes difficult to attach the housing 10 that covers the heat transfer member 91, making assembly of the electric motor 1A difficult. Additionally, if the heat transfer member 91A were to be fixed in a tilted position inside the housing case 10, it would be impossible to ensure an insulating distance between the circuit board 51A and the heat transfer member 91A, potentially preventing the desired electrical insulation characteristics from being achieved. Furthermore, tilting the heat transfer member 91A reduces the contact area between the electronic component 52A and the heat transfer member 91A, which face each other across the heat dissipation sheet 92A, increasing the thermal resistance between the electronic component 52A and the heat transfer member 91A, preventing the heat generated by the electronic component 52A from being effectively dissipated outside the electric motor 1A.

In contrast, in this embodiment, the support member 4 uses the support surface portion 41 to support at least a portion of the area on the lower surface 912 of the heat transfer member 91 that is not supported by the upper surface portion 523 of the electronic component 52. This prevents the heat transfer member 91 and heat dissipation sheet 92 from tilting relative to the circuit board 51, even if the heat transfer member 91 is positioned offset relative to the electronic component 52. Furthermore, by preventing the heat transfer member 91A from tilting, as described above, it is possible to obtain the desired electrical insulation characteristics and heat dissipation characteristics of the electronic component 52 (in other words, to facilitate heat transfer from the electronic component 52 to the housing case 10), and to improve assembly ease.

Furthermore, according to this embodiment, the heat transfer member 91 can be stably supported by the electronic components 52 and the support member 4 during and after assembly, making it easy to increase the size of the heat transfer member 91 and improve heat dissipation, enabling sufficient heat dissipation even when the electric motor 1 is increased in output.

Furthermore, according to this embodiment, even if the shape or size of the heat transfer member 91 is changed, the underside 912 of the heat transfer member 91 can be supported without changing the support member 4. Therefore, there is no need to change the shape of the support member 4 to match the size of the heat transfer member 91. (In addition, because there is no need for a process to connect the heat transfer member 91 to the support member 4, the process of assembling the electric motor 1 due to the support member 4 can be prevented from becoming complicated.)

The upper surface 523 of the electronic component 52 functions as a first support surface that supports the heat transfer member 91, and the support surface 41 of the support member 4 functions as a second support surface that supports the heat transfer member 91, thereby preventing the heat transfer member 91 from being fixed in an inclined position.

The support surface portion 41 (second support surface) of the support member 4 is formed in a position that does not overlap with the upper surface portion 523 (first support surface) when viewed perpendicular to the circuit board 51, thereby increasing the area that supports the heat transfer member 91 and enabling stable support of the heat transfer member 91. Furthermore, by using the upper surface portion 523 of the electronic component 52 as the support surface for the heat transfer member 91, a heat transfer path between the electronic component 52 and the heat transfer member 91 is reliably secured, thereby improving heat dissipation from the electronic component 52.

By positioning the support surface portion 41 radially outward of the upper surface portion 523, the heat transfer member 91 can be prevented from being fixed at an angle by the support member 4 even if it is positioned offset radially outward relative to the electronic component 52.

As described above, the second bearing accommodating portion 123 formed in the second housing case 12 is typically formed by press working. The annular recess 124 is also formed around the second bearing accommodating portion 123 by the press working (see FIG. 2). When assembling the electric motor 1, the heat transfer member 91 is placed on the electronic component 52 and then the second housing case 12 is placed axially over the electronic component 52, sandwiching the heat transfer member 91 between the circuit board 51 and the second housing case 12. As a result, the heat transfer member 91 is fixed inside the housing case 10 while being sandwiched between the circuit board 51 and the second housing case 12. At this time, the heat transfer member 91 is pushed into the recess 124 formed in the second housing case 12 and tends to be positioned toward the outer diameter side of the electric motor 1 (the area not supported by the electronic component 52) relative to the electronic component 52 (avoiding the recess 124, as shown in FIG. 2). As a result, the heat transfer member 91 tends to tilt toward the outer diameter of the motor 1, as shown in Figure 5.

However, in this embodiment, as shown in FIG. 2, the support surface portion 41 is formed on the first frame portion 401 (the frame portion located farthest from the recess 124 on the outer diameter side). Therefore, even if the heat transfer member 91 is positioned biased toward the outer diameter side, which is the area not supported by the electronic component 52 by the recess 124, the support surface portion 41 can support the heat transfer member 91 so that it does not fall over.

The restricting portion 42 is formed at a position on the outer frame portion 40 away from the support surface portion 41. By restricting the application area of the resin W applied to the lead portions 522, the application area can be restricted when electrically insulating the lead portions 522, and the resin W can be prevented from spreading onto the circuit board 51.

Furthermore, the restricting portion 42 is formed in a position that does not overlap with the support surface portion 41 when viewed from a direction perpendicular to the circuit board 51 (the direction of the rotational axis of the electric motor 1). As a result, even if resin W is accidentally applied to the upper surface of the restricting portion 42 that restricts the application range of the resin W, the support surface portion 41 is positioned away from the restricting portion 42, so the flatness of the support surface portion 41 that supports the heat transfer member 91 can be maintained, and the heat transfer member 91 can be stably supported.

Furthermore, because the second height H2 of the support surface portion 41 is higher than the first height H1 of the restricting portion 42, the resin W can be prevented from rising higher than the second height H2. This prevents the resin W from rising higher than the upper surface 523 of the electronic component 52, even if an excessive amount of resin W is applied or if resin W is applied to the upper surface of the restricting portion 42. If the height of the restricting portion 42 or the height of the resin W (first height H1) were higher than the second height H2 of the support surface portion 41, a gap that inhibits heat transfer would be created between the upper surface 523 of the electronic component 52 and the lower surface 912 of the heat transfer member 91, potentially preventing sufficient transfer of heat generated by the electronic component 52 to the heat transfer member 91. In other words, by making the second height H2 of the support surface portion 41 higher than the first height H1 of the restricting portion 42, a heat transfer path from the electronic component 52 to the heat transfer member 91 is reliably secured, thereby improving heat dissipation from the electronic component 52.

The outer frame 40 has a locking portion 43 that abuts against the side surface 524 of the main body 521 on which the lead portions 522 are formed. This not only makes it easier to position the support member 4 on the electronic component 52, but also prevents gaps from forming between the electronic component 52 and the support member 4. This ensures that the resin W can be applied over a sufficient area, allowing for stable application of the resin W and making it easier to ensure electrical insulation.

In addition, the locking portion 43 prevents gaps from forming between the electronic component 52 and the support member 4, ensuring that the heat transfer member 91 is stably supported without tilting due to the gap.

In this embodiment, the support base portions 410 having the support surface portions 41 are provided in four locations on the first frame portion 401, but this is not limited to this and they may be provided in two locations. Even when the first support base portions 410 are provided in the two locations described above, it is preferable that they are provided one at a time symmetrically from the center of the length of the first frame portion 401.

Furthermore, while the support surface portion 41 is shown as being rectangular, this is not limiting and the support surface portion 41 may also be circular or elliptical.

In addition, in this embodiment, the outer frame portion 40 continuously surrounds the outer periphery of the electronic component 52, but a portion of the outer frame portion 40 may be interrupted. For example, the outer frame portion 40 may be interrupted (cut out) in the center of the third frame portion 403 in the longitudinal direction. In this case, the support member 4 can be easily attached by expanding the third frame portion 403 side of the outer frame portion 40.

In addition, while the present embodiment illustrates a case in which the heat dissipation sheet 92 is disposed between the electronic component 52 and the support member 4, this is not limited to this. For example, an adhesive member (not shown) may be interposed between the lower surface 912 of the heat transfer member 91 and the support surface portion 41 of the support member 4. Furthermore, the lower surface 912 of the heat transfer member 91 may be in direct contact with the support surface portion 41 of the support member 4.

In addition, in this embodiment, the housing 10 of the electric motor 1 is configured from a member formed by pressing a metal plate, but this is not limited to this. For example, the housing 10 may be configured from a member formed by die-casting a metal such as aluminum. Also, for example, the housing 10 may be configured from a resin outer shell with a bottomed cylindrical opening formed integrally with the stator core, and a metal bracket that closes the opening of the resin outer shell.

REFERENCE SIGNS LIST 1, 1A... electric motor 2... stator 21... stator core 3... rotor 32... permanent magnet portion 4... support member 40... outer frame portion 41... support surface portion (second support surface)
42: Restricting portion 43: Locking portion 44: Protrusion portion 451, 452: Contact surface 453, 454: Contact surface forming portion 461, 462: Non-contact surface 463, 464: Non-contact surface forming portion 400: Space portion 5: Substrate portion 51: Circuit board 52: Electronic component 521: Main body portion 522: Lead portion 523: Upper surface portion (first support surface)
6...rotating shaft 91, 91A, 91B...heat transfer member 912...underside 92, 92A, 92B...heat dissipation sheet 93...adhesive member 10...accommodation case 11...first accommodation case 12...second accommodation case C...axial center H1...first height H2...second height

Claims (7)

a rotor having a rotating shaft;
a stator disposed on the outer diameter side of the rotor;
a housing case that houses the stator;
a circuit board disposed in an internal space covered by the housing case;
a heat transfer member that forms a heat transfer path between the circuit board and the housing case,
an electronic component having a first support surface that supports the heat transfer member and a support member having a second support surface that supports the heat transfer member together with the first support surface are disposed on the circuit board;
One surface of the heat transfer member is supported by the electronic component and the support member. 2. The electric motor according to claim 1 ,
the second support surface is formed at a position that does not overlap with the first support surface when viewed in a direction perpendicular to the circuit board. 3. The electric motor according to claim 1 or 2 ,
The second support surface is disposed on the outer diameter side of the first support surface. The electric motor according to any one of claims 1 to 3 ,
The electronic component has a main body and a lead extending from the main body,
The support member further has an outer frame portion that surrounds an outer periphery of the electronic component. 5. The electric motor according to claim 4 ,
the outer frame portion has a restricting portion that restricts the range of application of the resin to the lead portion,
the restricting portion is formed at a position that does not overlap with the second support surface when viewed in a direction perpendicular to the circuit board. 6. The electric motor according to claim 5 ,
The height of the second support surface from the circuit board is greater than the height of the restriction portion. The electric motor according to any one of claims 4 to 6 ,
the outer frame portion has a locking portion that abuts against a surface of the main body portion on which the lead portions are formed.