STATOR FOR AN ELECTRIC MOTOR

Abstract

This stator comprises a core, several coils wound around the core, a housing comprising at least two support columns in contact with an end face of the core, and a bridge connecting the at least two support columns, and a resin covering the core, the several coils, and the housing.

Description

Electric motor stator

[0001] The present disclosure relates to a stator for an electric motor.

[0002] Conventionally, the stator of an electric motor is molded with resin for purposes such as waterproofing (see, for example, Patent Document 1). Molding is a method in which an insert is loaded into a mold, and then resin is injected into the mold. That is, after the stator is loaded into the mold, resin is injected into the mold. As a result, the outside of the stator is covered with resin, and the resin is filled around the coils. In order to miniaturize a molded stator, it is necessary to reduce the thickness of the resin covering the outside of the stator.

[0003] Japanese Patent Application Laid-Open No. 2014-218063

[0004] To reduce the thickness of the resin covering the outside of the stator, it is necessary to narrow the gap between the mold and the outer part of the stator during molding. However, narrowing the gap may result in insufficient resin reaching the gap during molding. In other words, molding defects may occur during molding. To avoid molding defects, the resin injection pressure may be increased. However, increasing the injection pressure may damage stator components such as the coil.

[0005] Therefore, there is a need for a technology that can improve the flow of resin during molding without increasing the resin injection pressure.

[0006] The stator of the present disclosure comprises a housing having a core, a plurality of coils wound around the core, at least two struts abutting the end faces of the core, and a bridge connecting the at least two struts to each other, and a resin covering the core, the plurality of coils, and the housing.

[0007] Fig. 1 is a plan view of a stator before molding. Fig. 2 is an exploded plan view of a stator before molding. Fig. 3 is a right side view of a stator before molding. Fig. 4 is a left side view of a stator before molding. Fig. 5 is a plan view of a stator after molding. Fig. 6 is an exploded perspective view of a core. Fig. 7 is an exploded perspective view of a core. Fig. 8 is a schematic view for explaining the flow of resin during molding. Fig. 9 is a perspective view of a stator of another embodiment.

[0008] Hereinafter, a stator of an electric motor according to an embodiment of the present disclosure will be described with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplicate descriptions of those components may be omitted.

[0009] <One embodiment> Fig. 1A is a plan view of a stator before molding. Fig. 1B is an exploded plan view of a stator before molding. Fig. 1C is a right side view of a stator before molding. Fig. 1D is a left side view of a stator before molding. Fig. 2 is a plan view of a stator after molding. Figs. 3A and 3B are exploded perspective views of a core.

[0010] The stator 1 is a component that constitutes the electric motor and generates a magnetic force that rotates a rotor (not shown).

[0011] The stator 1 includes a core 2, a plurality of coils 3, an insulating portion 4, a first housing 5, a second housing 6, and a resin 7. At least one of the first housing 5 and the second housing 6 corresponds to the housing described in the claims.

[0012] The core 2 is a component that serves as a path for magnetic flux. The core 2 is manufactured by laminating a plurality of plate materials formed by press working or the like. The plate materials are, for example, electromagnetic steel plates.

[0013] The core 2 has a core back (not shown) formed in a substantially cylindrical shape, and teeth (not shown) extending from the core back toward the center.

[0014] The core 2 has a first end face 21 and a second end face 22. The first end face 21 is a face that constitutes an end portion in a first direction along the central axis of the core 2. The second end face 22 is a face that constitutes an end portion in a second direction along the central axis of the core 2. The second direction is the opposite direction to the first direction. At least one of the first end face 21 and the second end face 22 corresponds to an end face recited in the claims.

[0015] The plurality of coils 3 are wound around the teeth of the core 2. The plurality of coils 3 are made of, for example, copper wire.

[0016] The insulating portion 4 is a member interposed between the teeth and the coil 3 to insulate the teeth from the coil 3. The insulating portion 4 is made of a predetermined insulating material. A printed circuit board (not shown) may be embedded in the insulating portion 4.

[0017] 3B and other figures, when the insulating portion 4 covers the side portion of the coil 3, a resin hole (not shown) may be formed in the insulating portion 4 parallel to the central axis of the core 2. The resin hole formed in the insulating portion 4 is a hole through which the resin 7 passes when the stator 1 is molded. Furthermore, the resin hole formed in the insulating portion 4 is a hole into which the resin 7 is finally filled when the stator 1 is molded.

[0018] The first housing 5 is a member that covers at least a portion of the coil 3 wound around the core 2. The first housing 5 is attached to the first end surface 21 of the core 2 using, for example, screws or bolts and nuts.

[0019] A central hole 51 is formed in the first housing 5. The central hole 51 is a circular through-hole whose center is on the central axis of the core 2.

[0020] The first housing 5 includes at least an end surface member 52 and an outer peripheral member 53. The end surface member 52 is a member that is perpendicular to the central axis of the core 2. The outer peripheral member 53 is, for example, a member that is perpendicular to the end surface member 52 and extends toward the first end surface 21 of the core 2. The first housing 5 is, for example, integrally molded by casting.

[0021] One or more resin holes 521 are formed in the end surface member 52 parallel to the central axis of the core 2. The resin holes 521 are through holes. The resin holes 521 are holes through which the resin 7 passes when the stator 1 is molded. The resin holes 521 are also holes into which the resin 7 is finally filled when the stator 1 is molded.

[0022] The resin holes 521 are formed at positions corresponding to the spaces between the coils 3. The spaces between the coils 3 are the spaces between two coils wound around adjacent teeth. In other words, the resin holes 521 are formed so that the resin holes 521 and the spaces between the coils 3 are aligned in a straight line.

[0023] The second housing 6 is a member that covers at least a portion of the coil 3 wound around the core 2. The second housing 6 is attached to the second end surface 22 of the core 2 using, for example, screws or bolts and nuts.

[0024] The second housing 6 has at least two support columns 61, a bridge 62, and an end surface member 63. The at least two support columns 61, the bridge 62, and the end surface member 63 are integrally formed by, for example, casting.

[0025] At least two support columns 61 are members that abut against the second end face 22 of the core 2. Each support column 61 extends parallel to the central axis of the core 2. The cross section of each support column 61 may have any shape. Here, the cross section refers to a cross section that is perpendicular to the central axis of the core 2.

[0026] The bridge 62 is a member that connects at least two struts 61 to each other. The bridge 62 connects one end of each strut 61 to each other. Here, one end of each strut 61 refers to the end located opposite to the end that abuts against the second end face 22 of the core 2.

[0027] A gap is formed between the second end face 22 of the core 2 and the bridge 62. In other words, when the second housing 6 is attached to the core 2, a hole is formed at a position surrounded by the second end face 22, the two support posts 61, and the bridge 62. As will be described later, this gap or hole allows the resin 7 to pass through during molding. Furthermore, this gap is finally filled with the resin 7 during molding.

[0028] The end surface member 63 is a member that is perpendicular to the central axis of the core 2. The end surface member 63 covers the coil 3 and the insulating portion 4. A center hole 631 is formed in the end surface member 63. The center hole 631 is a circular through hole that is centered on the central axis of the core 2.

[0029] The end surface member 63 has component mounting holes 632 formed around the center hole 631. The component mounting holes 632 are, for example, screw holes. After the stator 1 is molded, various components are attached to the stator 1 using bolts or the like.

[0030] One or more resin holes 633 are formed in the end surface member 63 parallel to the central axis of the core 2. The resin holes 633 are through holes. The resin holes 633 are holes through which the resin 7 passes when the stator 1 is molded. The resin holes 633 are also holes into which the resin 7 is finally filled when the stator 1 is molded.

[0031] The resin 7 covers at least the core 2, the coil 3 and the housing. That is, the resin 7 covers the stator 1 by molding.

[0032] 4 is a schematic diagram illustrating the flow of resin 7 during molding. The stator 1 is loaded into a mold and molded by an injection molding machine. Specifically, the resin 7 flowing from an injection port (not shown) for the resin 7 collides with the end surface member 52 of the first housing 5, or flows along the outer surface of the outer peripheral member 53 without colliding with the end surface member 52.

[0033] The resin 7 that has flowed along the outer surface of the outer peripheral member 53 flows in the direction in which the second housing 6 is disposed. As a result, the outer surface of the stator 1 is covered with the resin 7.

[0034] Furthermore, the resin 7 flowing from the injection port collides with the end surface member 52 of the first housing 5, or flows from the center hole 51 of the first housing 5 toward the inside of the first housing 5 without colliding with the end surface member 52. Furthermore, the resin 7 flowing from the injection port flows from the resin hole 521 formed in the end surface member 52 of the first housing 5 toward the inside of the first housing 5.

[0035] The resin 7 flowing inside the first housing 5 passes between the coils 3 wound around the core 2. Here, the coil 3 refers to the coil 3 wound around one tooth. Therefore, the space between the coils 3 refers to the gap that exists between the coils 3 wound around two adjacent teeth.

[0036] A portion of the resin 7 that has passed between the coils 3 flows out from the gap formed between the second end face 22 of the core 2 and the bridge 62 of the second housing 6. The remainder of the resin 7 that has passed between the coils 3 flows toward the inside of the second housing 6. The resin 7 that has flowed toward the inside of the second housing 6 flows out from the resin holes 633 formed in the end face member 63 of the second housing 6. Note that, because a mold is placed in the central portion of the stator 1 where the rotor is assembled, the resin 7 does not flow into this central portion.

[0037] 5 is a perspective view of a stator 1 according to another embodiment. The bridges 62 of the second housing 6 have inclined surfaces 622 extending in a direction from an outer surface 621 of the bridges 62 toward the coil 3. The outer surface 621 of the bridges 62 is a surface of the bridges 62 that is parallel to the central axis of the core 2.

[0038] The inclined surface 622 extending in the direction toward the coil 3 is a surface formed by bending the outer surface 621 of the bridge 62 at a predetermined angle toward the central axis of the core 2. In this case, one end of the inclined surface 622 is disposed at the same height as the outer peripheral surface of the core 2. That is, the outer surface 621 of the bridge 62 is formed on the same plane as the outer peripheral surface of the core 2. Note that the "same plane" does not necessarily mean the same plane in a strict sense. Furthermore, the other end of the inclined surface 622 facing the one end is disposed more inward of the outer peripheral surface of the core 2.

[0039] The inclination angle of the inclined surface 622 is, for example, in the range of 10° to 45° from the outer surface 621 of the bridge 62. The angle of the inclined surface 622 may be, for example, 30°. Note that the inclined surface 622 formed on the bridge 62 may not be flat, but may be curved. In other words, the inclined surface 622 may have any shape as long as the resin can flow smoothly from the gap between the bridge 62 and the core 2 during molding.

[0040] Furthermore, the support 61 may have an inclined surface 612 extending in a direction from the outer surface 611 of the support 61 toward the central axis of the core 2. The outer surface 611 of the support 61 is a surface of the support 61 formed on the same plane as the outer surface 621 of the bridge 62. The inclined surface 612 extending in a direction toward the central axis of the core 2 is a surface formed by bending the outer surface 611 of the support 61 toward the central axis of the core 2 by a predetermined angle.

[0041] The inclination angle of the inclined surface 612 is, for example, in the range of 10° to 45° from the outer surface 611 of the support 61. The angle of the inclined surface 612 may be, for example, 30°. Note that the inclined surface 612 formed on the support 61 may not be a flat surface but may be a curved surface.

[0042] The stator 1 according to each of the above embodiments comprises a housing having a core 2, a plurality of coils 3 wound around the core 2, at least two pillars 61 abutting the end faces of the core 2, and a bridge 62 connecting the at least two pillars 61 to each other, and a resin 7 covering the core 2, the plurality of coils 3, and the housing.

[0043] Therefore, when the stator 1 is molded, the resin 7 flows out from the gap formed between the end face of the core 2 and the bridge 62. As a result, the flow of the resin 7 is improved when the stator 1 is molded, thereby preventing molding defects.

[0044] If this gap were not formed, in other words, if the gap were covered by the second housing 6, the flow of the resin 7 in the portion covering the gap would be poor. For example, if the gap between the second housing 6 and the mold is narrow in that portion, there is a risk that the resin 7 will not sufficiently reach that portion. The stator 1 of this embodiment solves this problem.

[0045] Furthermore, resin holes 633 are formed in the end surface members 63 of the housing, and the resin holes 633 are filled with the resin 7. That is, when the stator 1 is molded, the resin 7 passes through the resin holes 633. This further improves the flow of the resin 7 during molding. When molding is completed, the resin holes 633 are filled with the resin 7.

[0046] Furthermore, the bridge 62 has an inclined surface 622 that extends from the outer surface 621 of the bridge 62 toward the coil 3. Furthermore, the support 61 has an inclined surface 612 that extends from the outer surface 611 of the support 61 toward the central axis of the core 2. This allows the resin 7 that passes between the coil 3 during molding to smoothly flow out from the gap between the second end face 22 and the bridge 62. In other words, the flow of the resin 7 during molding is further improved.

[0047] Furthermore, one end of the inclined surface 622 and one end of the inclined surface 612 are positioned at the same height as the outer peripheral surface of the core 2, and the other end opposite to the one end is positioned more inward than the outer peripheral surface of the core 2. Therefore, the resin 7 flowing out from the gap between the second end face 22 of the core 2 and the bridge 62 smoothly merges with the resin 7 flowing along the outer peripheral surface of the core 2. In other words, the flow of the resin 7 during molding is improved.

[0048] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible to these embodiments without departing from the gist of the present disclosure or the gist of the present disclosure derived from the content of the claims and their equivalents. Furthermore, these embodiments can also be implemented in combination.

[0049] The following are supplementary notes related to embodiments of the present disclosure. Supplementary Note [1] A stator comprising: a housing having a core, a plurality of coils wound around the core, at least two support posts abutting an end face of the core, and a bridge connecting the at least two support posts to each other; and resin covering the core, the plurality of coils, and the housing. Supplementary Note [2] The stator according to Supplementary Note [1], wherein a resin hole is formed in an end face of the housing, and the resin is filled into the resin. Supplementary Note [3] The stator according to Supplementary Note [1] or [2], wherein the resin hole is formed at a position corresponding to a space between the plurality of coils. Supplementary Note [4] The stator according to any one of Supplements [1] to [3], wherein the support post has an inclined surface extending from an outer surface of the support post toward a central axis of the core. Supplementary Note [5] The stator according to any one of Supplements [1] to [4], wherein the bridge has an inclined surface extending from an outer surface of the bridge toward the plurality of coils. Supplementary note [6] The stator according to supplementary note [4] or [5], wherein one end of the inclined surface is positioned at the same height as the outer peripheral surface of the core, and the other end opposite to the one end is positioned inside the outer peripheral surface of the core.

[0050] REFERENCE SIGNS LIST 1 stator 2 core 21 first end face 22 second end face 3 coil 4 insulating portion 5 first housing 51 center hole 52 end face member 521 resin hole 53 outer peripheral member 6 second housing 61 support 611 outer surface 612 inclined surface 62 bridge 621 outer surface 622 inclined surface 63 end face member 631 center hole 632 component mounting hole 633 resin hole 7 resin

Claims

1. A stator comprising: a core; a plurality of coils wound around the core; a housing having at least two struts abutting the end faces of the core and a bridge connecting the at least two struts to each other; and a resin covering the core, the plurality of coils, and the housing.

2. The stator according to claim 1, wherein a resin hole is formed in an end face of the housing, and the resin is filled into the resin hole.

3. A stator according to claim 2, wherein the resin holes are formed at positions corresponding to the spaces between the coils of the plurality of coils.

4. A stator according to any one of claims 1 to 3, wherein the support pillar has an inclined surface that extends from the outer surface of the support pillar toward the central axis of the core.

5. A stator according to any one of claims 1 to 4, wherein the bridge has an inclined surface extending from the outer surface of the bridge toward the plurality of coils.

6. A stator according to claim 4 or 5, wherein one end of the inclined surface is positioned at the same height as the outer peripheral surface of the core, and the other end opposite to the one end is positioned inside the outer peripheral surface of the core.

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