Electric motor

Abstract

This electric motor is provided with: a rotor having a rotation shaft; a commutator attached to the rotation shaft; a brush in contact with the commutator; a stator for generating a magnetic force acting on the rotor; a frame in which the stator is housed; a resin plate disposed so as to cover the opening of the frame; and a seal member disposed on the bottom surface of a step part provided on the outer surface of an outer peripheral end part of the plate and positioned between a rising surface of the step part and an inner peripheral surface of the frame. A plurality of support parts for supporting the plate are provided along the circumferential direction on the inner peripheral surface of the frame. The plate has a plurality of reception parts for receiving the plurality of support parts. When a circle centered on the axis of the rotation shaft is equally divided into a plurality of regions along the circumferential direction by a plurality of division lines with the width of the brush as a reference unit, the plurality of reception parts are respectively positioned on the plurality of division lines.

Description

electric motor

[0001] The present disclosure relates to electric motors, and more particularly to commutator motors with brushes.

[0002] Electric motors are widely used in the fields of household electrical appliances such as electric vacuum cleaners, as well as in the field of electrical equipment for automobiles, etc. For example, in automobiles, electric motors are used in anti-lock brake systems (ABSs), air suspensions, radiator cooling fans, etc.

[0003] Known electric motors include commutator motors (brushed motors) that use brushes and brushless motors (brushless motors) that do not use brushes. Of these, commutator motors include a stator, a rotor that rotates due to the magnetic force of the stator, a commutator attached to the rotating shaft of the rotor, and brushes in contact with the commutator.

[0004] One known example of this type of commutator motor is one in which a resin plate is attached to cover an opening in a frame that houses a stator and a rotor (see, for example, Patent Document 1). In a motor with such a structure, brushes are held by the resin plate.

[0005] In the electric motor disclosed in Patent Document 1, in order to hold the plate in the frame, a plurality of support portions for supporting the plate are provided at intervals along the circumferential direction on the inner peripheral surface of the frame. A plurality of receiving portions for receiving the support portions of the frame are provided on the outer peripheral end of the plate, in accordance with the support portions provided on the frame.

[0006] Electric motors are often combined with mechanical components, for example. In this case, a ring-shaped seal (seal ring) made of elastomer or the like may be provided on the electric motor to ensure airtightness between the mechanical components and the electric motor. For example, in an electric motor in which a plate is attached to cover an opening in a frame, a seal is disposed on the bottom surface of a step provided on the outer surface of the outer peripheral end of the plate. The seal disposed in this manner is sandwiched between the raised surface of the stepped portion of the plate and the inner peripheral surface of the frame. In other words, the seal is inserted into an insertion groove surrounded by the bottom surface and raised surface of the stepped portion of the plate and the inner peripheral surface of the frame.

[0007] By using such a seal, the plate and seal that contact the mechanical component are pressed down toward the inside of the frame by the stress generated when the electric motor and mechanical component are assembled, so that the plate can be held in a specified position on the frame and the installation position of the seal can be maintained, thereby ensuring airtightness between the mechanical component and the electric motor (plate).

[0008] However, in conventional electric motors that have a structure in which the plate is fixed to the frame by abutting the receiving portions of the plate with the support portions of the frame, the multiple receiving portions provided on the outer peripheral edge of the plate are not evenly spaced along the circumferential direction. Therefore, the outer peripheral edge of the plate has areas where the receiving portions are spaced widely and areas where the receiving portions are spaced closely. Therefore, when force is applied to the plate when the electric motor is assembled with a mechanical component, creep is likely to occur in the areas where the receiving portions are spaced widely, and the areas where the receiving portions are spaced widely are pressed down toward the inside of the frame. In other words, the outer peripheral edge of the plate is partially pressed down along the circumferential direction, resulting in a partial reduction in the surface pressure between the seal member and the mechanical component. As a result, the filling rate of the seal member in the insertion groove decreases in the areas where the receiving portions are spaced widely, reducing the airtightness between the electric motor and the mechanical component.

[0009] In particular, in response to recent environmental changes or strengthened specifications required by customers, it is sometimes necessary to further improve the airtightness between mechanical parts and electric motors. One possible solution to this problem is to increase the filling rate of the seal material in the insertion groove. However, increasing the filling rate of the seal material increases the reaction force of the seal material on the insertion groove of the plate. This makes the plate more susceptible to creep. As a result, the airtightness between the motor and mechanical parts is significantly reduced. Furthermore, in automotive electric motors, external environmental changes (such as high temperature changes) are significant, which can further promote creep and significantly reduce the airtightness between the motor and mechanical parts.

[0010] Japanese Patent No. 7308456

[0011] The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide an electric motor that can suppress a decrease in airtightness between the electric motor and mechanical components.

[0012] In order to achieve the above object, one aspect of the electric motor according to the present disclosure comprises a rotor having a rotating shaft, a commutator attached to the rotating shaft, brushes in contact with the commutator, a stator that generates a magnetic force acting on the rotor, a frame in which the stator is housed, a resin plate arranged to cover an opening of the frame, and a sealing member that is arranged on the bottom surface of a step portion provided on the outer surface of the outer peripheral end of the plate and is located between the rising surface of the step portion and the inner peripheral surface of the frame, wherein a plurality of support portions that support the plate are provided along the circumferential direction on the inner peripheral surface of the frame, and the plate has a plurality of receiving portions that receive the plurality of support portions, and when a circle centered on the axis of the rotating shaft is equally divided into a plurality of regions along the circumferential direction by a plurality of dividing lines using the width of the brush as a reference unit, the plurality of receiving portions are each located on the plurality of dividing lines.

[0013] According to the present disclosure, it is possible to prevent a decrease in airtightness between the electric motor and the mechanical component.

[0014] FIG. 1 is a perspective view of an electric motor according to an embodiment. FIG. 2 is a cross-sectional view of the electric motor according to the embodiment taken along a plane passing through the axis of the rotating shaft. FIG. 3 is a perspective view of a plate in the electric motor according to the embodiment as viewed from the inner surface. FIG. 4 is a perspective view of a frame in the electric motor according to the embodiment. FIG. 5 is a cross-sectional perspective view showing a portion of the electric motor according to the embodiment taken along a plane passing through a support portion. FIG. 6 is a cross-sectional front view showing a portion of the electric motor according to the embodiment taken along a plane passing through a support portion. FIG. 7 is a cross-sectional view showing an example of an electric motor according to the embodiment combined with a mechanical component. FIG. 8 is a diagram for explaining the layout of a plurality of receiving portions provided on the plate. FIG. 9 is a diagram for explaining the layout of a plurality of support portions provided on the frame. FIG. 10 is a plan view of a plate in an electric motor of a comparative example. FIG. 11 is a plan view of a plate in an electric motor according to a first modification. FIG. 12 is a plan view of a plate in an electric motor according to a second modification. FIG. 13 is a plan view of a plate in an electric motor according to a third modification.

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present disclosure will be described as optional components.

[0016] Each figure is a schematic diagram and is not necessarily an exact representation. Therefore, the scales and the like are not necessarily the same in each figure. In all figures, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0017] In this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition. In this embodiment, for convenience, the direction in which the axis C of the rotating shaft 21 extends is defined as the up-down direction. However, this up-down direction may differ from the actual up-down direction depending on the usage state of the electric motor 1, etc. In this embodiment, the radial direction of the stator 10 and the rotor 20 is defined as the "radial direction," and the rotation direction of the rotor 20 is defined as the "circumferential direction." In other words, the direction perpendicular to the axis C of the rotating shaft 21 of the rotor 20 is defined as the "radial direction." The direction circumferentially around the axis C of the rotating shaft 21 is defined as the "circumferential direction." The direction in which the axis C of the rotating shaft 21 extends (the longitudinal direction of the rotating shaft 21) is defined as the "axial direction."

[0018] (Embodiment) The configuration of an electric motor 1 according to an embodiment will be described with reference to Figs. 1 to 4. Fig. 1 is a perspective view of the electric motor 1 according to an embodiment. Fig. 2 is a cross-sectional view of the electric motor 1 according to an embodiment taken along a plane passing through the axis C of the rotating shaft 21. Fig. 3 is a perspective view of a plate 70 in the electric motor 1 according to the embodiment as seen from the inner surface. Fig. 4 is a perspective view of a frame 60 in the electric motor 1 according to the embodiment.

[0019] The electric motor 1 is a commutator motor with brushes. As shown in Figures 1 to 3, the electric motor 1 includes a stator 10, a rotor 20, a commutator 30, brushes 40, brush springs 50, a frame 60, a plate 70, a seal member 80, a first bearing 91, and a second bearing 92.

[0020] The electric motor 1 is a direct current (DC) motor that is driven by direct current. As an example, the electric motor 1 is an in-vehicle motor used in an automobile. For example, the electric motor 1 is used in a hydraulic pump of an ABS (Anti-lock Brake System) that is installed in an automobile.

[0021] Hereinafter, each component of the electric motor 1 according to the embodiment will be described in detail.

[0022] The stator 10 generates a magnetic force acting on the rotor 20 to rotate it. The stator 10 is configured to generate magnetic flux on the air gap surface with the rotor 20. The stator 10 forms a magnetic circuit together with the rotor 20, which is an armature. The stator 10 is configured so that north and south poles alternate on the air gap surface with the rotor 20 along the circumferential direction of the rotating shaft 21 of the rotor 20. The stator 10 is a field magnet that creates magnetic flux to generate torque. In this embodiment, the stator 10 is made up of a plurality of magnets. The magnets that make up the stator 10 are, for example, permanent magnets having south and north poles.

[0023] The multiple magnets constituting the stator 10 are arranged so that north and south poles alternate evenly in the circumferential direction. Therefore, the direction of the main magnetic flux generated by the stator 10 (magnets) is perpendicular to the direction in which the axis C of the rotating shaft 21 extends. The multiple magnets are arranged at equal intervals in the circumferential direction so as to surround the rotor core 22 of the rotor 20. As an example, each magnet has an arc shape with a substantially constant thickness when viewed from above, i.e., from the direction in which the axis C extends. Each magnet is fixed to the frame 60. Specifically, each magnet is fixed to the inner circumferential surface of the frame 60 by adhesive, leaf springs, or the like.

[0024] The rotor 20 rotates due to the magnetic force generated in the stator 10. The rotor 20 has a rotation shaft 21. The rotor 20 rotates around the rotation shaft 21. Specifically, the rotor 20 rotates around the axis C of the rotation shaft 21.

[0025] The rotor 20 is an armature and includes a rotor core 22 and windings 23 wound around the rotor core 22. In Fig. 2, the windings 23 are shown schematically.

[0026] The rotating shaft 21 is a shaft that serves as the center of rotation of the rotor 20. As an example, the rotating shaft 21 is a metal rod made of a metal material such as stainless steel. The rotating shaft 21 extends in the longitudinal direction, which is the direction of the axis C.

[0027] The rotating shaft 21 passes through the rotor core 22. The rotating shaft 21 is fixed to the rotor core 22. Specifically, the rotating shaft 21 is fixed to the rotor core 22 in a state where it passes through the center of the rotor core 22 so as to extend on both sides of the rotor core 22. The rotating shaft 21 is fixed to the rotor core 22 by being press-fitted or shrink-fitted into a central hole formed in the rotor core 22.

[0028] The first portion 21a of the rotating shaft 21 protrudes from one side of the rotor core 22. The first portion 21a of the rotating shaft 21 is supported by the first bearing 91. The first portion 21a of the rotating shaft 21 is an output-side portion (output shaft) of the rotating shaft 21. Specifically, the first portion 21a of the rotating shaft 21 protrudes from the first bearing 91. A load is attached to the tip end (output-side end) of the rotating shaft 21 that protrudes from the first bearing 91.

[0029] On the other hand, the second portion 21b of the rotating shaft 21 protrudes from the other side of the rotor core 22. The second portion 21b of the rotating shaft 21 is supported by a second bearing 92. The second portion 21b of the rotating shaft 21 is a portion of the rotating shaft 21 on the counter-output side (counter-output shaft).

[0030] As an example, each of the first bearing 91 and the second bearing 92 is a bearing that rotatably supports the rotating shaft 21. In this way, the rotating shaft 21 is supported by the first bearing 91 and the second bearing 92 in a rotatable state. The first bearing 91 is fixed to the outer surface of the plate 70. The second bearing 92 is fixed to the bottom surface of the frame 60. Each of the first bearing 91 and the second bearing 92 is, for example, a ball bearing. However, the present invention is not limited to this.

[0031] The rotor core 22 is an armature core around which the windings 23 are wound. The rotor core 22 is a magnetic body made of a magnetic material. The rotor core 22 is, for example, a laminated body in which a plurality of punched electromagnetic steel sheets formed into a predetermined shape are stacked along the direction in which the axis C of the rotating shaft 21 extends. The rotor core 22 is not limited to a laminated body of electromagnetic steel sheets. The rotor core 22 may also be a bulk body made of a magnetic material. A small air gap exists between the outer peripheral surface of the rotor core 22 and the stator 10.

[0032] The rotor core 22 has a plurality of teeth 22a. The plurality of teeth 22a are formed radially so as to protrude in a radial direction, which is a direction perpendicular to the axis C of the rotating shaft 21. The plurality of teeth 22a are disposed at equal intervals across the rotation direction of the rotating shaft 21. A slot is formed between two adjacent teeth 22a.

[0033] 2, windings 23 are wound around rotor core 22. The electric wires constituting windings 23 are, for example, insulated wires. The electric wires constituting windings 23 include a conductive wire made of a conductive material such as copper as a core wire, and an insulating film that coats this conductive wire.

[0034] The windings 23 are wound around the rotor core 22 via insulators 24. The insulators 24 are made of an insulating resin material or the like. The insulators 24 are attached between the windings 23 and the rotor core 22. The windings 23 are provided in each slot of the rotor core 22.

[0035] The windings 23 are electrically connected to the commutator 30. Specifically, the windings 23 are electrically connected to commutator segments 31 of the commutator 30. When a current flows through the windings 23 via the commutator 30, the rotor 20 generates a magnetic force that acts on the stator 10. Specifically, when a current flows through the windings 23, each of the multiple teeth 22a of the rotor core 22 generates a magnetic force that acts on the stator 10. In this embodiment, the direction of the main magnetic flux generated by the stator 10 is radially from the rotating shaft 21. The windings 23 are concentrated windings. The windings 23 are wound around each of the multiple teeth 22a via insulators 24.

[0036] The rotor 20 is an inner rotor. As shown in Fig. 2, the rotor 20 is disposed inside the stator 10. Specifically, the rotor core 22 of the rotor 20 is surrounded by a plurality of magnets that constitute the stator 10, with a minute air gap between the rotor 20 and the stator 10.

[0037] A commutator 30 is attached to the rotating shaft 21 of the rotor 20. Therefore, the commutator 30 rotates together with the rotating shaft 21. The commutator 30 is attached to a portion of the rotating shaft 21 between the rotor core 22 and the first bearing 91.

[0038] As shown in FIG. 2 , the commutator 30 has a plurality of commutator bars 31 (commutator segments). The commutator bars 31 are arranged at equal intervals in a circular ring shape surrounding the rotating shaft 21. The commutator bars 31 are conductive terminals made of a metal material such as copper. Each of the commutator bars 31 is electrically connected to the windings 23 of the rotor 20. As an example, the commutator 30 is a molded commutator. The commutator 30 is configured such that the commutator bars 31 are molded in resin. In this case, the commutator bars 31 are embedded in the molded resin so that their surfaces are exposed. The commutator bars 31 are insulated and separated from one another. However, for example, two adjacent commutator bars 31 are connected to each other by the windings 23.

[0039] As shown in FIG. 2 , brushes 40 are in contact with the commutator 30. Specifically, the brushes 40 are in contact with the commutator segments 31 of the commutator 30. The brushes 40 are power supply brushes (conductive brushes) that supply power to the windings 23 of the rotor 20. Specifically, as shown in FIG. 3 , a pigtail wire 45 through which current supplied from a power source flows is connected to the brushes 40. When the brushes 40 are in contact with the commutator segments 31, the current (armature current) supplied to the brushes 40 via the pigtail wire 45 flows through the commutator segments 31 to the windings 23 of the rotor 20. As an example, the brushes 40 are carbon brushes made of carbon. Specifically, the brushes 40 are carbon brushes containing a metal such as copper. The brushes 40 are elongated in their initial state before wear. As an example, the brushes 40 are elongated and substantially rectangular parallelepiped.

[0040] 2 , the brush 40 has a front end surface 41 that is a surface that contacts the commutator 30, and a rear end surface 42 that is a surface opposite to the front end surface 41. The front end surface 41 is an end surface at the front end, which is one end in the longitudinal direction of the brush 40. The rear end surface 42 is an end surface at the rear end, which is the other end in the longitudinal direction of the brush 40. The front end surface 41 is a sliding contact surface that comes into sliding contact with the commutator segments 31 of the commutator 30.

[0041] The brushes 40 are arranged so that their longitudinal direction is perpendicular to the axis C of the rotating shaft 21 (i.e., the radial direction of rotation of the rotating shaft 21). In this embodiment, a plurality of brushes 40 are arranged. Specifically, two brushes 40 are arranged. In this case, a pair of brushes 40 is provided, arranged opposite each other with the commutator 30 in between so as to sandwich the commutator 30. A front end surface 41, which is the inner tip of each brush 40, abuts against the commutator segments 31 of the commutator 30. When the motor 1 operates and the rotating shaft 21 rotates, the commutator 30 rotates as well, so that the front end surface 41 of each brush 40 continues to come into contact with all of the commutator segments 31 in sequence.

[0042] Each brush 40 is disposed so as to be in sliding contact with the commutator 30. As shown in Fig. 2, each brush 40 receives a pressing force from a brush spring 50 and is constantly in contact with the commutator 30 while the motor 1 is in operation. Specifically, the front end surface 41 of each brush 40 is constantly in contact with the commutator segments 31 of the commutator 30. In this manner, each brush 40 is pressed against the commutator 30 by the brush spring 50.

[0043] The brush spring 50 is an elastic member for pressing the brush 40 against the commutator 30. The brush spring 50 is arranged in a one-to-one correspondence with the brush 40. A portion of the brush spring 50 contacts the rear end surface 42 of the brush 40. The brush spring 50 applies a pressure (spring pressure) to the brush 40 by means of a spring elastic force (spring restoring force). This urges the brush 40 toward the commutator 30. In this embodiment, the brush spring 50 is a compression coil spring. The brush spring 50 is not limited to a compression coil spring. The brush spring 50 may be a torsion spring, a constant force spring, or the like.

[0044] The brush 40 is held by a plate 70. As shown in FIG. 3 , the brush 40 is housed in a brush holder 71 provided on the plate 70. The brush 40 housed in the brush holder 71 slides within the brush holder 71 by being pressed by the brush spring 50. Therefore, to allow the brush 40 to slide smoothly within the brush holder 71, it is preferable to provide an appropriate gap (clearance) between the inner surface of the brush holder 71 and the outer surface of the brush 40. The brush 40, pressed against the brush spring 50, moves within the brush holder 71 toward the commutator 30 as the front end surface 41 of the brush 40 wears. Specifically, the brush 40 moves in a direction perpendicular to the axis C of the rotating shaft 21, i.e., in the radial direction.

[0045] 2 , the frame 60 is a housing (case) that houses the stator 10. That is, the frame 60 houses the stator 10. The frame 60 houses not only the stator 10 but also the rotor 20. Specifically, the frame 60 houses the rotor core 22 and the windings 23 of the rotor 20.

[0046] 2 and 4, the frame 60 is a cylindrical housing with a bottom and an opening 61. The frame 60 is cylindrical with a bottom. Therefore, the opening shape of the opening 61 of the frame 60 is circular. The frame 60 is a metal frame made of a metal material such as an iron-based material. The frame 60 may be made of a resin material instead of a metal material.

[0047] As shown in FIG. 4 , a plurality of support portions 62 (frame support portions) that support the plate 70 are provided on the inner peripheral surface 60a of the frame 60. The support portions 62 are provided at intervals along the circumferential direction. That is, the support portions 62 are arranged in an annular shape when viewed from above. In this embodiment, twelve support portions 62 are provided at equal intervals along the circumferential direction. Therefore, the twelve support portions 62 are provided at intervals of 30°.

[0048] The multiple support portions 62 are convex portions formed in a protruding shape. Each of the multiple support portions 62 protrudes from the inner peripheral surface 60a of the frame 60 toward the rotation shaft 21. The support portions 62 are part of the frame 60. Specifically, the support portions 62 are formed by processing a part of the inner peripheral surface 60a of the frame 60 into a convex shape. For example, the support portions 62 can be formed by hitting the outer peripheral surface 60b of the frame 60 with a jig such as a punch. In this case, a recess is formed in the outer peripheral surface 60b of the frame 60. In other words, the support portions 62 have a shape formed by extruding a thick portion of the cylindrical portion of the frame 60.

[0049] FIG. 5 is a cross-sectional perspective view showing a portion of the electric motor 1 according to the embodiment when cut along a plane passing through the support portion 62. FIG. 6 is a cross-sectional front view showing a portion of the electric motor 1 according to the embodiment when cut along a plane passing through the support portion 62. As shown in FIGS. 5 and 6 , the cross-sectional shape of the protruding portion of the support portion 62 is, for example, a triangle. Specifically, the cross-sectional shape of the support portion 62 is a right-angled triangle. In this case, the cross-sectional shape of the recess formed in the outer peripheral surface 60b of the frame 60 is also a right-angled triangle. The cross-sectional shape of the support portion 62 is not limited to a triangle and may be a rectangle, a semicircle, or the like.

[0050] 5 and 6 , the support portion 62 has a support surface 62a that supports the plate 70. The support surface 62a is a flat surface. The support surface 62a has a constant width in the radial direction. The support surface 62a extends linearly or arcuately along the circumferential direction. The support surface 62a is not limited to a flat surface.

[0051] The frame 60 also functions as a bracket that holds the second bearing 92. Therefore, the frame 60 is provided with a bearing holder 63 that holds the second bearing 92. In this embodiment, the bearing holder 63 is a recess provided in the bottom of the frame 60, and the second bearing 92 is disposed inside the frame 60.

[0052] As shown in Fig. 2, the plate 70 is a cover disposed to cover the opening 61 of the frame 60. That is, the plate 70 covers the opening 61 of the frame 60. Therefore, the plate 70 has a circular shape in a plan view. The plate 70 is formed in a disk shape as a whole. As shown in Fig. 3, the plate 70 is provided with a through-hole 70c through which the rotation shaft 21 passes.

[0053] The plate 70 is fitted into the opening 61 of the frame 60. In this embodiment, the plate 70 is fitted into the opening 61 of the frame 60 by press-fitting. For example, the plate 70 can be fixed to the frame 60 by forcing the plate 70 into the opening 61 of the frame 60. In this case, the side end surface of the outer peripheral end of the plate 70 is in contact with the inner peripheral surface 60a of the frame 60. Note that the side end surface of the outer peripheral end of the plate 70 does not have to be in contact with the inner peripheral surface 60a of the frame 60.

[0054] The plate 70 is a resin plate made of a resin material. For example, the plate 70 is made of polyphthalamide (PPA) or nylon 66. The plate 70 is an injection-molded product integrally formed from a resin material.

[0055] 2, the frame 60 and the plate 70 constitute the outer casing of the electric motor 1. The outer casing constituted by the frame 60 and the plate 70 not only houses the stator 10 and the rotor 20, but also other components that constitute the electric motor 1, such as the commutator 30 and the brushes 40.

[0056] The plate 70 also functions as a holding member (brush holder) that holds the brush 40. Specifically, as shown in FIG. 3 , the plate 70 has a brush holding portion 71 for holding the brush 40. The brush 40 is stored in the brush holding portion 71. In other words, the brush holding portion 71 is a brush storage portion that stores the brush 40. The brush holding portion 71 is a part of the plate 70. The brush holding portion 71 is provided on the inner surface 70a of the plate 70.

[0057] A brush holder 71 is provided for each brush 40. In this embodiment, since two brushes 40 are used, two brush holders 71 are provided on the plate 70.

[0058] Each brush holder 71 is formed in a concave shape on the inner surface of the plate 70. Each brush holder 71 is elongated with the direction in which the brush 40 moves as the longitudinal direction. In this embodiment, each brush holder 71 is elongated in a direction perpendicular to the axis C of the rotary shaft 21 (i.e., the radial direction of the rotation of the rotary shaft 21). Each brush holder 71 has a concave cross-sectional shape.

[0059] As shown in Figure 3, the brush holder 71, which houses the brushes 40, is covered by a cover plate 100. The cover plate 100 is, for example, a metal cover made of a metal plate. The cover plate 100 is arranged to cover the brush holder 71. The cover plate 100 is provided with locking claws. The cover plate 100 can be fixed to the plate 70 by inserting the locking claws into locking holes formed in the plate 70.

[0060] The brush 40 stored in the brush holder 71 is surrounded on all four sides by the brush holder 71 and the cover plate 100. In other words, the brush holder 71 and the cover plate 100 form a substantially rectangular cylindrical brush box that stores the brush 40.

[0061] Each brush holder 71 houses a brush spring 50 as well as a brush 40. Therefore, the longitudinal length of the brush holder 71 is longer than the length of the brush 40. The brush spring 50 is held by being sandwiched between the rear end surface 42 of the brush 40 and the rear end of the brush holder 71. The cover plate 100 covers not only the brush 40 but also the brush spring 50.

[0062] As shown in FIG. 3 , the plate 70 has receiving portions 72 (plate receiving portions) that receive the support portions 62 provided on the frame 60. The receiving portions 72 are support receiving portions that support the support portions 62 of the frame 60. A plurality of receiving portions 72 are provided to match the plurality of support portions 62. Specifically, the number of receiving portions 72 is the same as the number of support portions 62. The receiving portions 72 and the support portions 62 correspond one-to-one. In this embodiment, since twelve support portions 62 are provided on the frame 60, twelve receiving portions 72 are provided on the plate 70.

[0063] The plurality of receiving portions 72 are provided at intervals along the circumferential direction, similar to the plurality of support portions 62. That is, the plurality of receiving portions 72 are arranged in an annular shape. In this embodiment, like the support portions 62, twelve receiving portions 72 are provided at equal intervals along the circumferential direction. Therefore, the twelve receiving portions 72 are provided at intervals of 30°.

[0064] 3, 5, and 6, the plurality of receiving portions 72 are provided on the outer peripheral edge of the plate 70. The plurality of receiving portions 72 are provided on the inner surface 70a of the plate 70. Specifically, each of the plurality of receiving portions 72 is a recess formed in a concave shape in a part of the plate 70. Each of the plurality of receiving portions 72 is formed so as to recess the inner surface 70a of the plate 70.

[0065] The receiving portion 72 serves as an abutment portion that abuts against the support portion 62 of the frame 60. The receiving portion 72 has an abutment surface 72a (receiving surface) that abuts against the support surface 62a of the support portion 62 of the frame 60. The abutment surface 72a is flat. The abutment surface 72a has a constant width in the radial direction. The abutment surface 72a extends linearly or arcuately along the circumferential direction. Note that the abutment surface 72a is not limited to being flat.

[0066] The circumferential length of the receiving portion 72 is longer than the circumferential length of the support portion 62 of the frame 60. In other words, the circumferential length of the abutment surface 72a of the receiving portion 72 is longer than the circumferential length of the support surface 62a of the support portion 62. In this case, the circumferential length of the receiving portion 72 is preferably 1.4 times or more the circumferential length of the support portion 62 of the frame 60. In other words, the circumferential length of the abutment surface 72a of the receiving portion 72 is preferably 1.4 times or more the circumferential length of the support surface 62a of the support portion 62. Making the circumferential length of the abutment surface 72a of the receiving portion 72 1.4 times or more the circumferential length of the support surface 62a of the support portion 62 is preferable from the perspective of manufacturing for the following reasons.

[0067] That is, when the plate 70 is formed from a resin material, there is a risk of variations occurring in the receiving portions 72. However, by making the circumferential length of the abutment surface 72a of the receiving portion 72 at least 1.4 times the circumferential length of the support surface 62a of the support portion 62, it is possible to absorb the variations occurring in the receiving portions 72. Furthermore, when the support portions 62 are formed on the frame 60 using a jig, it is possible to absorb the variations occurring in the support portions 62. Because there are multiple receiving portions 72 and multiple support portions 62, it is possible to stably absorb the variations occurring in these portions.

[0068] Furthermore, the circumferential length of the receiving portion 72 is preferably 1.8 times or less the circumferential length of the support portion 62 of the frame 60. In other words, the circumferential length of the abutting surface 72a of the receiving portion 72 is preferably 1.8 times or less the circumferential length of the support surface 62a of the support portion 62. If the circumferential length of the abutting surface 72a of the receiving portion 72 is 1.8 times or less the circumferential length of the support surface 62a of the support portion 62, the electric motor 1 is preferable in the following respects.

[0069] That is, if the length of the receiving portion 72 is too long, there is a concern that the receiving portion 72 may not be able to sit properly, i.e., may not be stable, on the support portion 62. Therefore, by setting the circumferential length of the receiving portion 72 to an appropriate length, the stability of the receiving portion 72 on the support portion 62 can be ensured.

[0070] Furthermore, if the length of the receiving portion 72 is increased, the range of the portion where the thickness of the wall surface is thinned becomes wider by forming the receiving portion 72 on the wall surface that forms the outer periphery of the plate 70. Therefore, by appropriately setting the length of the receiving portion 72, the strength of the wall surface that forms the outer periphery of the plate 70 can be appropriately maintained.

[0071] As shown in Fig. 2, a step portion 73 is provided at the outer peripheral edge of the plate 70. The step portion 73 is provided on the outer surface 70b of the plate 70. The step portion 73 is formed in an annular shape around the entire circumference of the outer peripheral edge of the plate 70. The step portion 73 is a groove-like recess formed in a concave shape in a portion of the plate 70. For example, the step portion 73 is formed by reducing the thickness of the outer peripheral edge of the plate 70.

[0072] 5 and 6, the stepped portion 73 thus formed has a bottom surface 73a and a rising surface 73b. The bottom surface 73a of the stepped portion 73 is a step-down bottom surface that is one step lower and is a plane that is parallel to a plane perpendicular to the rotation axis 21. The rising surface 73b of the stepped portion 73 is a step side surface that is a plane perpendicular to the bottom surface 73a. Therefore, the cross-sectional shape of the stepped portion 73 is L-shaped.

[0073] A seal member 80 is disposed in the step portion 73. Specifically, the seal member 80 is disposed on the bottom surface 73a of the step portion 73. The seal member 80 is located between the rising surface 73b of the step portion 73 and the inner circumferential surface 60a of the frame 60. Specifically, the seal member 80 is inserted into an insertion groove SP having a concave cross section that is surrounded by the bottom surface 73a of the step portion 73, the rising surface 73b of the step portion 73, and the inner circumferential surface 60a of the frame 60. The insertion groove SP is formed in an annular shape at the outer circumferential end of the plate 70.

[0074] The width (radial length) of the bottom surface 73a of the step portion 73 is slightly shorter than the width of the seal member 80. Therefore, the seal member 80 arranged in the step portion 73 is sandwiched between the rising surface 73b of the step portion 73 and the inner circumferential surface 60a of the frame 60. For example, the seal member 80 is held in the step portion 73 by being press-fitted into the insertion groove SP.

[0075] The seal member 80 is an annular seal ring that ensures airtightness between the frame 60 and the plate 70. Therefore, the seal member 80 held in the step portion 73 of the plate 70 contacts the inner peripheral surface 60a of the frame 60. The seal member 80 also ensures airtightness between the electric motor 1 and a mechanical component to which the electric motor 1 is attached.

[0076] As shown in Fig. 1, the seal member 80 has an annular shape. The seal member 80 has rubber elasticity and is made of a resin material such as an elastomer. As shown in Figs. 5 and 6, the cross-sectional shape of the seal member 80 is, for example, an X-shape. However, this is not limiting. For example, the cross-sectional shape of the seal member 80 may be a circle, a rectangle, or the like.

[0077] A first bearing 91 is held on the outer surface 70b of the plate 70. Therefore, the plate 70 also functions as a bracket that holds the first bearing 91. The first bearing 91 is disposed on and fixed to the outer surface 70b of the plate 70.

[0078] A recess 74 is formed in the outer surface 70b of the plate 70. The recess 74 is a reservoir tank for temporarily storing liquid such as oil leaking from mechanical parts around the electric motor 1. The recess 74 is formed by depressing a portion of the outer surface 70b.

[0079] The plate 70 also holds components other than the brush 40. Specifically, as shown in Fig. 3, the plate 70 holds a power terminal 110, a ground terminal 120, and a choke coil 130. Specifically, a pair of power terminals 110, one ground terminal 120, and a pair of choke coils 130 are arranged and fixed on an inner surface 70a of the plate 70.

[0080] The pair of power supply terminals 110 are power supply terminals for supplying power from an external power supply. One of the pair of power supply terminals 110 is a positive power supply terminal connected to the positive side of the DC power supply. The other of the pair of power supply terminals 110 is a negative power supply terminal connected to the negative side of the DC power supply. The pair of power supply terminals 110 are fixed to the plate 70 by, for example, being fitted into the plate 70.

[0081] The ground terminal 120 (earth terminal) is connected to the metal frame 60. The ground terminal 120 is electrically connected to components that make up the circuit of the electric motor 1. For example, the ground terminal 120 is connected to a capacitor for removing electromagnetic noise.

[0082] The ground terminal 120 is provided on the outer peripheral edge of the plate 70. Specifically, the ground terminal 120 is located on the circumference of a circle formed by the plurality of receptacles 72 arranged in an annular shape. In other words, the ground terminal 120 is arranged in an annular shape together with the plurality of receptacles 72.

[0083] The choke coil 130 is inserted in the current path between the brush 40 and the power supply terminal 110. The choke coil 130 is arranged in a one-to-one correspondence with the brush 40. In this embodiment, two brushes 40 are arranged, and therefore two choke coils 130 are arranged. One of the two choke coils 130 is inserted in the current path between one of the two brushes 40 and one of the pair of power supply terminals 110. The other of the two choke coils 130 is inserted in the current path between the other of the two brushes 40 and the other of the pair of power supply terminals 110. By arranging the choke coil 130 in this manner, it is possible to remove noise contained in the current flowing in the current path between the brush 40 and the power supply terminal 110. Note that the choke coil 130 may not be arranged, and the brush 40 and the power supply terminal 110 may be directly connected.

[0084] In the electric motor 1 configured as described above, current supplied to the brushes 40 via the power supply terminals 110 flows as an armature current (drive current) through the commutator 30 to the windings 23 of the rotor 20, generating magnetic flux in the rotor 20. The magnetic force generated by the interaction between the magnetic flux generated in the rotor 20 and the magnetic flux generated from the stator 10 becomes torque that rotates the rotor 20. At this time, the direction of the current flow is switched depending on the positional relationship when the commutator segments 31 and the brushes 40 come into contact. In this way, switching the direction of the current flow generates a rotational force in a fixed direction due to the magnetic repulsive and attractive forces generated between the stator 10 and the rotor 20. This rotational force causes the rotor 20 to rotate about the axis C of the rotating shaft 21.

[0085] The electric motor 1 configured as described above is combined with, for example, a mechanical component. FIG. 7 is a cross-sectional view showing an example of the electric motor 1 according to the embodiment combined with a mechanical component 2. In this case, as shown in FIG. 7 , when the outer surface 2 a of the mechanical component 2 is abutted against the frame 60 and combined with the electric motor 1, the portion of the seal member 80 protruding from the insertion groove SP is pressed by the outer surface 2 a of the mechanical component 2. In other words, the seal member 80 is subjected to stress not only in the radial direction of the rotating shaft 21 but also in the axial direction. This causes the seal member 80 to elastically deform and be pressed into the insertion groove SP. As a result, airtightness between the mechanical component 2 and the electric motor 1 can be ensured. In particular, the elastically deformed seal member 80 being pressed into the insertion groove SP increases the filling rate of the seal member 80 in the insertion groove SP. Therefore, high airtightness between the mechanical component 2 and the electric motor 1 can be ensured.

[0086] Next, a design method for the layout of the plurality of receiving portions 72 provided on the plate 70 and the support portions 62 provided on the frame 60 will be described in detail with reference to FIGS. 8 and 9. FIG. 8 is a diagram for explaining the layout of the plurality of receiving portions 72 provided on the plate 70. FIG. 8 is a plan view of the plate 70 with various components such as the brush 40 held on its inner surface 70a. FIG. 9 is a diagram for explaining the layout of the plurality of support portions 62 provided on the frame 60. FIG. 9 is a top view of the frame 60.

[0087] As shown in Fig. 8 , when a circle centered on the axis C of the rotating shaft 21 is equally divided into a plurality of regions by a plurality of dividing lines DL along the circumferential direction of the axis C of the rotating shaft 21, the plurality of receiving portions 72 are located on the plurality of dividing lines DL. The plurality of dividing lines DL equally divide the circle centered on the axis C of the rotating shaft 21 into a plurality of regions, with the width of the brush 40 being the smallest reference unit. For example, the circle constituting the outline of the plate 70 is equally divided into a plurality of regions by dividing lines DL, with the width of the brush 40 being the smallest reference unit. In this case, the circle constituting the outline of the plate 70 is equally divided into n regions by n dividing lines DL.

[0088] The division lines DL are equal division lines that divide a circle centered on the axis C of the rotating shaft 21 into multiple regions around the axis C of the rotating shaft 21. Therefore, the division lines DL are boundary lines that indicate the boundaries between two adjacent regions among the multiple equally divided regions. The multiple division lines DL exist at equal intervals along the circumferential direction around the axis C of the rotating shaft 21. Therefore, the angle (pitch angle) θ between two adjacent division lines DL among the multiple division lines DL is the same. For example, if the circle that constitutes the outline of the plate 70 is equally divided into n regions by n division lines DL, then θ = 360° / n. Each of the multiple regions equally divided by the division lines DL is a sector. The arc lengths of the multiple regions are the same.

[0089] In this way, each of the plurality of receiving portions 72 is located on a corresponding one of the plurality of dividing lines DL, which are set with the width of the brush 40 as the minimum arrangement pitch. In other words, each of the plurality of receiving portions 72 overlaps the corresponding dividing line DL. Each of the plurality of receiving portions 72 is arranged so as to straddle the corresponding dividing line DL.

[0090] In Figure 8, a circle (the circle constituting the outline of the plate 70) centered on the axis C of the rotating shaft 21 is equally divided into 12 regions by 12 parting lines DL. Therefore, the angle (pitch angle) between two adjacent parting lines DL is 30°. The 12 receiving portions 72 are located on the 12 parting lines DL, respectively.

[0091] As shown in Fig. 9, the support portions 62 of the frame 60 into which the plate 70 is fitted are arranged to correspond to the receiving portions 72 provided on the plate 70. Specifically, the support portions 62 are located on the parting lines DL. The parting lines DL shown in Fig. 9 are the same as the parting lines DL shown in Fig. 8.

[0092] Therefore, like the receiving portions 72, each of the support portions 62 is located on a corresponding one of the plurality of dividing lines DL, which are set with the width of the brush 40 as the minimum arrangement pitch. In other words, each support portion 62 also overlaps the corresponding dividing line DL. Each support portion 62 is also arranged so as to straddle the corresponding dividing line DL. Specifically, the 12 support portions 62 are located on the 12 dividing lines DL, respectively.

[0093] As with the receiving portion 72, the radial center lines of the support portions 62 all coincide with the parting lines DL. That is, the radial center line of each of the twelve support portions 62 coincides with the corresponding parting line DL among the twelve parting lines DL.

[0094] Next, the effects of the electric motor 1 according to the embodiment will be described in comparison with an electric motor 1X of a comparative example, including how the technology of the present disclosure was developed. Fig. 10 is a plan view of a plate 70X in the electric motor 1X of the comparative example.

[0095] 10, a plate 70X in an electric motor 1X of the comparative example has a plurality of receiving portions 72X arranged in an annular configuration to receive support portions of the plate 70X. However, the receiving portions 72X are not arranged at equal intervals in the circumferential direction.

[0096] Therefore, if the electric motor 1X of the comparative example is combined with the mechanical component 2 as shown in FIG. 7 , a force is applied to the plate 70X. As a result, creep is more likely to occur in the areas of the multiple receiving portions 72X arranged in an annular shape where the receiving portions 72X are spaced apart widely. As a result, the areas of the plate 70X where the receiving portions 72X are spaced apart widely are pressed down toward the inside of the frame. In other words, the outer peripheral edge of the plate 70X is partially pressed down along the circumferential direction. This partially reduces the surface pressure between the seal member 80 and the mechanical component 2. As a result, the filling rate of the seal member 80 in the insertion groove SP decreases in the areas of the plate 70X where the receiving portions 72X are spaced apart widely. This therefore reduces the airtightness between the electric motor 1X and the mechanical component 2.

[0097] To solve this problem, the inventors first considered increasing the number of receiving portions 72X on the plate 70X and reducing the spacing between the receiving portions 72X. However, because the receiving portions 72X are provided on the outer peripheral edge of the plate 70X, and structures such as the brush 40 or brush holder are present on the outer peripheral edge of the plate 70X, there is a limit to how many receiving portions 72X can be increased. In other words, reducing the spacing between the receiving portions 72X could result in interference between the receiving portions 72X and the rear ends of the brushes 40. To address this issue, shortening the length of the brushes 40 could be considered to prevent interference between the receiving portions 72X and the rear ends of the brushes 40. However, shortening the length of the brushes 40 would shorten the life of the brushes 40 and, ultimately, the life of the electric motor 1X.

[0098] Therefore, the inventors have discovered a design method in which, as shown in Fig. 8, the brush 40 is allowed to be present up to the outer peripheral edge of the plate 70, and multiple receiving portions 72 are arranged using the width of the brush 40 as the smallest reference unit. Thus, the inventors have arrived at the technique of the present disclosure.

[0099] Specifically, when a circle centered on the axis C of the rotating shaft 21 is divided evenly into multiple regions along the circumferential direction by multiple dividing lines DL, with the width of the brush 40 used as the reference unit, the multiple receiving portions 72 are each located on the multiple dividing lines DL.

[0100] In this way, by positioning the receiving portions 72 on the dividing lines DL that evenly divide the circle, it is possible to make the spacing between the receiving portions 72 of the multiple receiving portions 72 more uniform. In other words, it is possible to reduce the difference in spacing between the portions with wide spacing between the receiving portions 72 and the portions with narrow spacing between the receiving portions 72 at the outer peripheral edge of the plate 70.

[0101] Furthermore, the plurality of dividing lines DL are set with the width of the brush 40 as the minimum reference unit (minimum arrangement pitch). Therefore, even if the brush 40 is present up to the outer periphery of the plate 70, the intervals between the receiving portions 72 can be made nearly equal.

[0102] With this configuration, even if a force is applied to the plate 70 when the electric motor 1 and the mechanical component 2 are combined, it is possible to prevent a portion of the outer peripheral edge of the plate 70 from being pressed down inward of the plate 70. This makes it possible to prevent creep from occurring in the plate 70. This makes it possible to prevent a portion of the outer peripheral edge of the plate 70 from being pressed down, thereby partially reducing the filling rate of the seal member 80 in the insertion groove SP, i.e., reducing the airtightness between the electric motor 1 and the mechanical component 2.

[0103] Furthermore, in the electric motor 1 according to this embodiment, the radial center line of each of the plurality of receiving portions 72 coincides with the corresponding one of the plurality of parting lines DL.

[0104] This configuration allows the spacing between the receiving portions 72 to be uniform for all of the plurality of receiving portions 72. This minimizes creep at the outer peripheral edge of the plate 70. This further prevents a decrease in airtightness between the electric motor 1 and the mechanical component 2.

[0105] In addition, in the electric motor 1 according to this embodiment, the circumferential length of the receiving portion 72 of the plate 70 is 1.4 times or more the circumferential length of the support portion 62 of the frame 60 .

[0106] This configuration can effectively prevent creep from occurring at the outer peripheral end of the plate 70. This can further prevent a decrease in airtightness between the electric motor 1 and the mechanical component 2.

[0107] In addition, in the electric motor 1 according to this embodiment, the circumferential length of the receiving portion 72 of the plate 70 is 1.8 times or less the circumferential length of the support portion 62 of the frame 60 .

[0108] This configuration can prevent the formation of a portion where the wall thickness is thinner than necessary at the outer peripheral end of the plate 70. This further prevents a decrease in airtightness between the electric motor 1 and the mechanical component 2.

[0109] (Modification) The electric motor 1 according to the present disclosure has been described above based on the embodiment, but the present disclosure is not limited to the above embodiment.

[0110] For example, in the above embodiment, the radial center lines of all of the multiple receiving portions 72 provided on the plate 70 coincide with the corresponding dividing lines DL. However, this is not limited to this. FIG. 11 is a plan view of a plate 70A in an electric motor 1A according to a first modification. Specifically, as in the plate 70A in the electric motor 1A shown in FIG. 11 , the multiple receiving portions 72 may include receiving portions 72A whose radial center lines 72L and dividing lines DL (equal dividing lines) do not coincide with each other. In other words, it is sufficient that at least a portion of the receiving portion 72 overlaps the dividing line DL. In this case, not all of the multiple receiving portions 72 are provided at equal intervals along the circumferential direction. The multiple support portions 62 provided on the frame 60 may be provided at positions corresponding to the receiving portions 72 and not be provided at equal intervals along the circumferential direction, as in the above embodiment, as long as they can abut against the receiving portions 72.

[0111] In the above embodiment, the brush 40 is located at the outer circumferential edge of the plate 70, and therefore the placement of the receiving portions 72 is considered with the width of the brush 40 as the smallest reference unit (minimum placement pitch). However, if the ground terminal 120 is also located at the outer circumferential edge of the plate 70, the placement of the receiving portions 72 must be considered to avoid interference between the receiving portions 72 and the ground terminal 120. In this case, since the width of the brush 40 is greater than the width of the ground terminal 120 in the above embodiment, the multiple regions separated by the dividing line DL are equally divided with the width of the brush 40 as the smallest reference unit. However, this is not limited to this. FIG. 12 is a plan view of the plate 70 in an electric motor 1B according to a second modification. For example, if the width of the ground terminal 120 is greater than the width of the brush 40, as in the electric motor 1B shown in FIG. 12, the multiple regions separated by the dividing line DL may be equally divided with the width of the ground terminal 120 as the smallest reference unit. In other words, the multiple regions divided by the dividing lines DL may be equally divided using at least one of the width of the brush 40 and the width of the ground terminal 120 as a reference unit. In Fig. 12, the circle constituting the plate 70 is equally divided into nine regions by nine dividing lines DL. Therefore, the angle between two adjacent dividing lines DL is 40°.

[0112] In the above embodiment, the two brushes 40 are arranged linearly with the commutator 30 interposed therebetween. However, this is not limiting. For example, the two brushes 40 may be arranged radially (e.g., in a V-shape) around the axis C of the rotating shaft 21. Alternatively, four brushes 40 may be arranged, as in the electric motor 1C shown in FIG. 13 . FIG. 13 is a plan view of a plate 70C in an electric motor 1C according to a third modification. In this case, two pairs of brushes 40 are provided, each pair facing each other across the commutator 30. In each pair of brushes 40, the angle between one pair of brushes 40 and the other pair of brushes 40 is, for example, approximately 60°. The receiving portions 72 are omitted in FIG. 13 . However, multiple receiving portions 72 are provided on the plate 70C using a design method similar to that of the above embodiment.

[0113] In the above embodiment, the support portion 62 is a part of the frame 60. However, this is not limiting. For example, the support portion 62 may be a component that is separately attached to the frame 60.

[0114] In the above embodiment, the stator 10 is made up of a magnet. However, this is not limiting. For example, the stator 10 may be made up of a stator core and a winding wound around the rotor core.

[0115] In the above embodiment, the electric motor 1 has been described as being used in an automobile. However, this is not limiting. That is, the electric motor 1 in the above embodiment can be used in various electrical appliances. For example, the electric motor 1 may be used in household electrical appliances such as vacuum cleaners or refrigerators, in industrial appliances such as automotive appliances and robots, or in power tools.

[0116] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments and variations that would occur to a person skilled in the art, or forms realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. The present disclosure also includes any combination of two or more claims from the multiple claims set forth in the claims at the time of filing, provided that there is no technical contradiction. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of the technical contradiction, the present disclosure also includes all combinations of claims included in that multiple claim or multiple multiple claims.

[0117] The present disclosure can be used in various products equipped with electric motors, including automobiles and the like.

[0118] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C Electric motor 2 Mechanical part 2a Outer surface 10 Stator 20 Rotor 21 Rotating shaft 21a First portion 21b Second portion 22 Rotor core 22a Teeth 23 Winding 24 Insulator 30 Commutator 31 Commutator segment 40 Brush 41 Front end surface 42 Rear end surface 45 Pigtail wire 50 Brush spring 60 Frame 60a Inner peripheral surface 60b Outer peripheral surface 61 Opening 62 Support portion 62a Support surface 63 Bearing holder 70, 70A, 70C Plate 70a Inner surface 70b Outer surface 70c Through hole 71 Brush holder 72, 72A Receiving portion 72a Contact surface 72L Radial center line 73 Step portion 73a Bottom surface 73b Rising surface 74 Recessed portion 80 Sealing member 91 First bearing 92 Second bearing 100 Cover plate 110 Power terminal 120 Ground terminal 130 Choke coil SP Insertion groove DL Parting line

Claims

1. A rotor having a rotating shaft, a commutator attached to the rotating shaft, a brush in contact with the commutator, a stator that generates a magnetic force acting on the rotor, a frame that houses the stator, a resin plate disposed so as to cover an opening of the frame, and a seal member disposed on a bottom surface of a step portion provided on an outer surface of an outer peripheral end portion of the plate and located between a rising surface of the step portion and an inner peripheral surface of the frame. A plurality of support portions for supporting the plate are provided along the circumferential direction on the inner peripheral surface of the frame. The plate has a plurality of receiving portions for receiving the plurality of support portions. When a circle centered on the axis of the rotating shaft is evenly divided into a plurality of regions along the circumferential direction by a plurality of dividing lines with the width of the brush as a reference unit, each of the plurality of receiving portions is located on one of the plurality of dividing lines. An electric motor.

2. The electric motor according to claim 1, wherein a radial center line of each of the plurality of receiving portions coincides with a corresponding one of the plurality of dividing lines.

3. The electric motor according to claim 1, wherein the plurality of receiving portions include a receiving portion in which a radial center line of the receiving portion does not coincide with the corresponding dividing line.

4. The electric motor according to claim 1, wherein a circumferential length of the receiving portion is 1.4 times or more of a circumferential length of the support portion.

5. The electric motor according to claim 1, wherein a circumferential length of the receiving portion is 1.8 times or less of a circumferential length of the support portion.

6. The electric motor according to any one of claims 1 to 5, wherein the brush is held by the plate.

7. Further having a ground terminal held by the plate, wherein the plurality of regions are evenly divided with at least one of the width of the brush and the width of the ground terminal as a reference unit. The electric motor according to any one of claims 1 to 5.

8. The electric motor according to claim 7, wherein the width of the brush is larger than the width of the ground terminal, and the plurality of regions are evenly divided with the width of the brush as a reference unit.

9. The electric motor according to claim 7, wherein the width of the ground terminal is larger than the width of the brush, and the plurality of regions are evenly divided with the width of the ground terminal as a reference unit.

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