Electric motor

Abstract

This electric motor comprises: a rotor having a rotating shaft extending in the shaft center direction; a commutator attached to the rotating shaft; a brush contacting the commutator; a brush holder having a brush housing portion for housing the brush and a through-hole through which the rotating shaft passes; and a conductive wire, one end portion of which is connected to the brush. The brush holder is provided with one or more guide portions that guide the conductive wire when the conductive wire moves as the brush is abraded.

Description

electric motor

[0001] The present disclosure relates to electric motors.

[0002] Electric motors are used in a variety of products, including household appliances such as vacuum cleaners, industrial equipment such as semiconductor manufacturing equipment, and vehicles such as automobiles. For example, electric motors are used to rotate rotary fans in electric blowers mounted on vacuum cleaners. Electric motors are also used in electronic stability control (ESC) systems in two-wheeled and four-wheeled automobiles.

[0003] Known electric motors include commutator motors, which use brushes, and brushless motors, which 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] In a commutator motor, brushes are housed in a brush housing portion. Conventionally, a commutator motor has been proposed in which the brush housing portion is provided on the inner surface of a brush holder that covers an opening of a housing that houses a rotor and a stator (see Patent Document 1).

[0005] A pigtail wire is connected to the brush of the commutator motor, and for example, one end of the pigtail wire is fixed to a side surface of the brush, and the other end is fixed to a power terminal and an electronic component such as a choke coil.

[0006] The pigtail wire connected to the brush moves as the brush slides due to wear of the brush. As the pigtail wire moves, its shape changes. In particular, the pigtail wire is a braided wire or a twisted wire. Therefore, as the pigtail wire moves, not only its shape but also its thickness changes.

[0007] In an electric motor having a plate-shaped brush holder that covers an opening in a housing, the pigtail wire is placed in the brush holder together with the brush. In this case, the brush holder is formed with a concave-convex structure of various sizes, such as a brush storage section.

[0008] The pigtail wires attached to the brush holders move toward the commutator as the motor operates and the brushes wear. As the pigtail wires change shape and thickness, they can interfere with the uneven structure of the brush holder. This can result in a reduction in the pressure the brushes exert on the commutator.

[0009] In this way, when the pressure of the brushes against the commutator decreases, poor conduction between the brushes and the commutator can occur, even though the effective wear portion of the brushes remains, and the motor may lose its function, shortening its lifespan.

[0010] JP 2013-135493 A

[0011] The present disclosure has been made to solve such problems, and has an object to provide an electric motor that can suppress a decrease in lifespan.

[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 extending in an axial direction, a commutator attached to the rotating shaft, brushes in contact with the commutator, a brush holder having a through hole through which the rotating shaft passes and a brush storage section for storing the brushes, and conductive wires having one end connected to the brushes, wherein the brush holder is provided with one or more guide sections for guiding the conductive wires as they move as the brushes wear.

[0013] According to the present disclosure, it is possible to prevent a decrease in the pressing pressure of the brushes against the commutator, and therefore to prevent a decrease in the life of the electric motor.

[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 rotation axis of the electric motor. FIG. 3 is an exploded perspective view of the electric motor according to the embodiment. FIG. 4 is a perspective view of a brush holder in the electric motor according to the embodiment, in which various components are arranged, as viewed from the inner surface. FIG. 5 is a perspective view of the brush holder in the electric motor according to the embodiment, as viewed from the inner surface. FIG. 6 is a perspective view of a brush holder in an electric motor of a comparative example, as viewed from the inner surface. FIG. 7 is a plan view of the brush holder in the electric motor using the brush holder of FIG. 6, as viewed from the inner surface, for illustrating movement of a pigtail wire when the brush wears and slides. FIG. 8 is an enlarged cross-sectional view of the brush holder and a brush in the electric motor using the brush holder of FIG. 6, for illustrating movement of a pigtail wire when the brush wears and slides. FIG. 9 is a plan view of the brush holder in the electric motor according to the embodiment, as viewed from the inner surface, for illustrating movement of a pigtail wire when the brush wears and slides. FIG. 10 is an enlarged cross-sectional view of the brush holder and the brush in the electric motor according to the embodiment, illustrating the movement of the pigtail wire when the brush wears and slides.

[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, components, the arrangement and connection of the components, steps, and the order of steps 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 a precise illustration. In each figure, the same reference numerals are used for components that are substantially the same as those in other figures, and duplicate explanations are omitted or simplified. 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.

[0017] (Embodiment) First, 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 the embodiment. Fig. 2 is a cross-sectional view of the electric motor 1 when cut along a plane passing through a rotating shaft 21 of the electric motor 1 according to the embodiment. Fig. 2 shows only the portion that appears in the cross section. Fig. 3 is an exploded perspective view of the electric motor 1 according to the embodiment. Fig. 4 is a perspective view of the brush holder 70 in the electric motor 1 according to the embodiment, in which various components are arranged, as viewed from the inner surface side.

[0018] The electric motor 1 is a commutator motor with brushes. As shown in Figures 1 to 4, the electric motor 1 includes a stator 10, a rotor 20, a commutator 30, brushes 40, pigtail wires 45, brush springs 50, a frame 60, a brush holder 70, a first bearing 81, and a second bearing 82. The electric motor 1 further includes a seal member 90 to ensure airtightness of the frame 60.

[0019] The electric motor 1 is a direct current motor (DC motor) 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) installed in the automobile. Each component of the electric motor 1 will be described in detail below.

[0020] 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. The stator 10 is composed of multiple magnets. The magnets that make up the stator 10 are, for example, permanent magnets with south and north poles.

[0021] 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., when viewed in 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 with an adhesive, a leaf spring, or the like.

[0022] 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.

[0023] The rotor 20 is an armature and includes a rotor core 22 and a winding 23 wound around the rotor core 22. In Fig. 2, the winding 23 is shown schematically.

[0024] 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.

[0025] 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.

[0026] The first portion 21a of the rotating shaft 21 protrudes from one side of the rotor core 22. The first portion 21a is supported by the first bearing 81. 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 81. A load is attached to the tip end (output-side end) of the rotating shaft 21 that protrudes from the first bearing 81.

[0027] 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 82. 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).

[0028] As an example, the first bearing 81 and the second bearing 82 are bearings that rotatably support the rotating shaft 21. In this way, the rotating shaft 21 is rotatably supported by the first bearing 81 and the second bearing 82. The first bearing 81 is fixed to the brush holder 70. The second bearing 82 is fixed to the frame 60.

[0029] 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 in the direction of the axis C of the rotating shaft 21. The rotor core 22 is not limited to a laminated body of electromagnetic steel sheets, but 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.

[0030] 3, 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 that is a direction perpendicular to the axis C of the rotating shaft 21. The plurality of teeth 22a are disposed at equal intervals in the rotation direction of the rotating shaft 21. A slot is formed between two adjacent teeth 22a.

[0031] 2 and 3, windings 23 are wound around the rotor core 22. The electric wires constituting the windings 23 are, for example, insulated wires. The electric wires constituting the windings 23 include a conductive wire made of a conductive material such as copper as a core wire, and an insulating film that coats the conductive wire.

[0032] 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 for each slot of the rotor core 22.

[0033] The windings 23 are electrically connected to the commutator 30. Specifically, the windings 23 are electrically connected to the 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. The direction of the main magnetic flux generated by the rotor 20 (teeth 22a) is radial, with the rotation axis 21 as the center. The windings 23 are concentrated windings. The windings 23 are wound around each of the multiple teeth 22a via insulators 24.

[0034] 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 the multiple magnets that constitute the stator 10, with a small air gap between it and the stator 10.

[0035] 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 81.

[0036] As shown in FIGS. 2 and 3 , the commutator 30 has a plurality of commutator bars 31 (commutator segments). The commutator bars 31 are arranged in a circular pattern at equal intervals around the rotating shaft 21. The commutator bars 31 are conductive terminals made of a metal material such as copper. The commutator bars 31 are 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. 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. For example, two adjacent commutator bars 31 or commutator bars 31 located at different positions are connected by the windings 23.

[0037] 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. 4 , 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 to the windings 23 of the rotor 20 via the commutator segments 31. In other words, the current supplied from the power source is supplied to the commutator segments 31 via the pigtail wire 45 and the brushes 40. The current supplied to the commutator segments 31 is passed through 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 brush 40 has an elongated shape in an initial state before it is worn, and is, for example, an elongated substantially rectangular parallelepiped.

[0038] The brush 40 has a front end face 40a that is in contact with the commutator 30, and a rear end face 40b that is the face opposite to the front end face 40a. The front end face 40a is an end face at the front end, which is one end in the longitudinal direction of the brush 40. The rear end face 40b is an end face at the rear end, which is the other end in the longitudinal direction of the brush 40. The front end face 40a is a sliding contact surface that comes into sliding contact with the commutator segments 31 of the commutator 30.

[0039] 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). 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. The front end surface 40a, which is the inner tip of each brush 40, abuts against the commutator segments 31 of the commutator 30. When the electric motor 1 operates and the rotating shaft 21 rotates, the commutator 30 also rotates, so that the front end surface 40a of each brush 40 continues to come into contact with all of the commutator segments 31 in sequence.

[0040] Each brush 40 is arranged to be able to slide against 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 40a of each brush 40 is constantly in contact with the commutator segments 31 of the commutator 30. In this way, each brush 40 is pressed against the commutator 30 by the brush spring 50.

[0041] As shown in Fig. 4, a pigtail wire 45 is connected to the brush 40. Specifically, a first end 45a, which is one end of the pigtail wire 45, is connected to the brush 40. The first end 45a of the pigtail wire 45 is fixed to a side surface of the brush 40. For example, the first end 45a of the pigtail wire 45 is fixed to the brush 40 by being embedded in the side surface of the brush 40. The first end 45a of the pigtail wire 45 is connected to a side surface of the brush 40 at a portion rearward (closer to the rear end) of the brush 40 relative to the center in the longitudinal direction.

[0042] The pigtail wire 45 is an example of a conductive wire. Current supplied from the power supply terminal 100 flows through the pigtail wire 45. In other words, the pigtail wire 45 is a power supply line for supplying power to the brush 40. Therefore, when the brush 40 comes into contact with the commutator segments 31, the current (armature current) supplied to the brush 40 via the pigtail wire 45 flows through the commutator segments 31 to the windings 23 of the rotor 20.

[0043] The other end of the pigtail wire 45, that is, a second end 45b, is fixed to the choke coil 110. The second end 45b of the pigtail wire 45 and the choke coil 110 are fixed together by welding such as spot welding.

[0044] 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 40b of the brush 40. The brush spring 50 applies pressure (spring pressure) to the brush 40 by its spring elastic force (spring restoring force). This urges the brush 40 toward the commutator 30. The brush spring 50 is a compression coil spring. The brush spring 50 is not limited to a compression coil spring, and may be a torsion spring or the like.

[0045] The brush 40 is housed in a brush housing portion 71 provided in the brush holder 70. The brush 40 housed in the brush housing portion 71 slides within the brush housing portion 71 by being pressed by the brush spring 50. Therefore, it is preferable to provide an appropriate gap (clearance) between the inner surface of the brush housing portion 71 and the outer surface of the brush 40 so that the brush 40 can slide smoothly within the brush housing portion 71. The brush 40 pressed against the brush spring 50 moves within the brush housing portion 71 toward the commutator 30 as the front end surface 40a 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.

[0046] The frame 60 (housing) is a case that houses the stator 10. That is, the frame 60 houses the stator 10. The frame 60 also houses the rotor 20. Specifically, the frame 60 houses the rotor core 22 and the windings 23 of the rotor 20.

[0047] The frame 60 is a substantially cylindrical housing with a bottom and an opening 60a. In the present embodiment, the frame 60 is substantially cylindrical with a bottom. 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 conductive resin material instead of a metal material.

[0048] The frame 60 also serves as a bracket that holds the second bearing 82. Therefore, the frame 60 is provided with a bearing holder 61 that holds the second bearing 82. The second bearing 82 is disposed inside the frame 60.

[0049] As shown in FIG. 2 , the brush holder 70 is a plate-shaped cover disposed so as to cover the opening 60a of the frame 60. That is, the brush holder 70 covers the opening 60a of the frame 60. The opening shape of the opening 60a of the frame 60 is circular. Therefore, the shape of the brush holder 70 in a top view is also circular. The brush holder 70 is fitted into the opening 60a of the frame 60. The brush holder 70 is pressed into the open end of the frame 60 by press-fitting. In this way, the brush holder 70 is fixed to the open end of the frame 60. Therefore, the side surface of the outer peripheral end of the brush holder 70 contacts the inner surface of the open end of the frame 60.

[0050] The frame 60 and the brush holder 70 constitute an outer casing of the electric motor 1. The outer casing constituted by the frame 60 and the brush holder 70 accommodates not only 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.

[0051] 2 and 4, the brush holder 70 is a holding member that holds the brush 40. Specifically, the brush holder 70 has a brush storage portion 71 as a brush holding portion for holding the brush 40.

[0052] The brush holder 70 also serves as a bracket that holds the first bearing 81. The first bearing 81 is fixed to the brush holder 70. As shown in Figures 1 and 2, the first bearing 81 is disposed on the outer surface of the brush holder 70 and fixed thereto.

[0053] 1 and 3, a recess 70a is formed on the outer surface of the brush holder 70. The recess 70a is a reservoir tank for temporarily storing liquid such as oil that leaks from mechanical parts around the electric motor 1. The recess 70a is formed so as to protrude inward, recessing a portion of the outer surface.

[0054] As shown in FIG. 3, a step portion 70b on which the seal member 90 is placed is formed on the outer surface of the brush holder 70. The step portion 70b is formed in a flange shape at the outer peripheral end of the brush holder 70. The step portion 70b is formed in an annular shape around the entire circumference of the brush holder 70. The step portion 70b is formed by reducing the thickness of the outer peripheral end of the brush holder 70. As shown in FIG. 2, the seal member 90 is sandwiched between the rising surface of the step portion 70b and the inner surface of the frame 60. Specifically, the seal member 90 is fixed to the step portion 70b by being press-fitted into the step portion 70b.

[0055] The seal member 90 placed on the step portion 70b is an annular seal ring for ensuring airtightness between the frame 60 and the brush holder 70. The seal member 90 contacts the inner surface of the frame 60. As shown in FIG. 3, the seal member 90 is annular. The seal member 90 has rubber elasticity. The seal member 90 is made of a resin material such as an elastomer, or an elastic material.

[0056] The brush holder 70 is made of a resin material. That is, the brush holder 70 is a resin plate made of resin. For example, the brush holder 70 is made of polyphthalamide (PPA) or nylon 6. The brush holder 70 is a resin-molded product integrally formed from a resin material.

[0057] As shown in FIG. 4 , a pair of power terminals 100 and a choke coil 110 are arranged on the inner surface (inner surface) of the brush holder 70. Specifically, the pair of power terminals 100 are arranged in a terminal arrangement portion 70c provided on the brush holder 70. The terminal arrangement portion 70c is, for example, a recess provided on a protruding portion protruding from the inner surface of the brush holder 70. Each of the pair of power terminals 100 is fixed to the brush holder 70, for example, by being inserted into the terminal arrangement portion 70c. The pair of choke coils 110 are arranged in a coil arrangement portion 70d provided on the brush holder 70. Each of the pair of choke coils 110 is fixed to the brush holder 70, for example, by a locking claw provided on the inner surface of the brush holder 70. The coil arrangement portion 70d is, for example, a recess formed by recessing the inner surface of the brush holder 70.

[0058] The pair of power supply terminals 100 are power supply terminals for supplying power from an external power supply. One of the pair of power supply terminals 100 is a positive power supply terminal connected to the positive side of a DC power supply. The other of the pair of power supply terminals 100 is a negative power supply terminal connected to the negative side of the DC power supply.

[0059] The choke coil 110 is inserted in the current path between the brush 40 and the power supply terminal 100. This makes it possible to remove noise contained in the current flowing in the current path between the brush 40 and the power supply terminal 100.

[0060] The choke coils 110 are arranged in one-to-one correspondence with the brushes 40. In this embodiment, two brushes 40 are arranged, and therefore two choke coils 110 are arranged. One of the two choke coils 110 is inserted in the current path between one of the two brushes 40 and one of the pair of power supply terminals 100. The other of the two choke coils 110 is inserted in the current path between the other of the two brushes 40 and the other of the pair of power supply terminals 100.

[0061] Specifically, in each choke coil 110, one end of the choke coil 110 is fixed to the second end 45b of the pigtail wire 45. As described above, one end of the choke coil 110 and the second end 45b of the pigtail wire 45 are connected and fixed by welding or the like.

[0062] The coil wire of the choke coil 110 is hard. Therefore, the tip portion of the choke coil 110 does not contact the brush holder 70 and is floating above the inner surface of the brush holder 70. Therefore, the connection portion CP (welded portion), where one end of the choke coil 110 and the second end 45b of the pigtail wire 45 are connected, does not contact the brush holder 70, and a gap exists between the connection portion CP and the brush holder 70. There does not have to be a gap between the connection portion CP and the brush holder 70. In other words, the connection portion CP may be in contact with the brush holder 70.

[0063] The other end of each choke coil 110 is electrically connected to the power supply terminal 100 via a conductive member. The other end of the choke coil 110 and the power supply terminal 100 may be directly connected.

[0064] In the electric motor 1 configured as described above, current supplied to the brushes 40 via the power supply terminals 100 flows as an armature current (drive current) through the commutator 30 to the windings 23 of the rotor 20. This generates magnetic flux in the rotor 20. The magnetic flux generated in the rotor 20 interacts with the magnetic flux generated by the stator 10, generating a magnetic force that serves as torque to rotate the rotor 20. At this time, the direction of the current flow is switched depending on the positional relationship between the commutator segments 31 and the brushes 40 when they come into contact. By switching the direction of the current flow in this way, a rotational force in a fixed direction is generated by the magnetic repulsive and attractive forces generated between the stator 10 and the rotor 20, causing the rotor 20 to rotate about the axis C of the rotating shaft 21.

[0065] Next, the detailed configuration of the brush holder 70 will be described using Fig. 5 while referring to Figs. 2 to 4. Fig. 5 is a perspective view of the brush holder 70 in the electric motor 1 according to the embodiment, as viewed from the inner surface side. Fig. 5 is a view of Fig. 4 with the various components arranged on the brush holder 70 omitted. Only the brush holder 70 is shown in Fig. 5.

[0066] As shown in Figures 4 and 5, various uneven structures are integrally formed on the inner surface of the resin brush holder 70. Various components are arranged on the inner surface of the brush holder 70. These components are held by the brush holder 70. Specifically, the brushes 40, pigtail wires 45, power terminals 100, choke coils 110, cover plates 120, etc. are arranged on the inner surface of the brush holder 70.

[0067] The brush holder 70 has a brush storage portion 71 that stores the brush 40. The brush storage portion 71 is a part of the brush holder 70. The brush storage portion 71 is provided on the inner surface of the brush holder 70.

[0068] A brush storage section 71 is provided for each brush 40. In this embodiment, two brushes 40 are used. Therefore, as shown in Figures 4 and 5, two brush storage sections 71 are provided in the brush holder 70.

[0069] Each brush housing 71 has a brush opening 71a on the commutator 30 side (rotary shaft 21 side) for exposing the front end faces 40a of the brushes 40. The brushes 40 housed in the brush housing 71 protrude from the brush opening 71a and come into contact with the commutator segments 31 of the commutator 30.

[0070] Each brush housing 71 is formed by forming the brush holder 70 into a concave shape. Each brush housing 71 is elongated, with the direction in which the brush 40 moves as the longitudinal direction. Each brush housing 71 is elongated in a direction perpendicular to the axis C of the rotary shaft 21 (i.e., in the radial direction of the rotary shaft 21). Each brush housing 71 has a concave cross-sectional shape.

[0071] As shown in FIG. 5 , each brush housing 71 has a pair of side walls, a first side wall 711 and a second side wall 712, that sandwich the brush 40. The pigtail wire 45 is connected to the side surface of the brush 40. Therefore, one of the first side wall 711 and the second side wall 712 has a portion that is shorter in height than the other. In this embodiment, the first side wall 711 has a low-back portion 713 that is a portion that is shorter in height than the second side wall 712. The pigtail wire 45 passes over the low-back portion 713 of the first side wall 711 and is pulled out from the side of the brush housing 71. The low-back portion 713 of the first side wall 711 extends to the brush opening 71 a. As a result, the pigtail wire 45 pulled out from the side of the brush storage section 71 passes over the low back portion 713 of the first side wall 711 and approaches the commutator 30 as the brush 40 wears and slides toward the commutator 30.

[0072] Of the first side wall 711 and the second side wall 712, a step portion 714 is provided on the outer side surface of the first side wall 711. The step portion 714 is formed in a staircase shape. The step portion 714 is formed with only one step. The step portion 714 has a step surface 714a that is one step lower than the top surface of the low-back portion 713 of the first side wall 711. The step portion 714 may be formed with multiple steps.

[0073] As shown in FIG. 4 , the brush housing 71 is covered by a cover plate 120. That is, the cover plate 120 covers the brushes 40. The cover plate 120 is, for example, a metal cover made of a metal plate. The cover plate 120 is arranged to cover the brush housing 71. The cover plate 120 is provided with locking claws. The locking claws can be press-fitted into locking holes formed in the brush holder 70 to secure the cover plate 120 to the brush holder 70. The locking holes are formed, for example, in the first side wall 711 and the second side wall 712.

[0074] The brush 40 stored in the brush storage section 71 is surrounded on all four sides by the brush storage section 71 and the cover plate 120. In other words, the brush storage section 71 and the cover plate 120 form a substantially rectangular cylindrical brush box that stores the brush 40. Because the first side wall 711 that forms the brush storage section 71 has a low back portion 713, part of the side of the brush box formed by the brush storage section 71 and the cover plate 120 is open. The pigtail wire 45 connected to the brush 40 is pulled out from an opening provided in the side of the brush box.

[0075] As shown in Figure 2, each brush housing 71 houses a brush spring 50 as well as a brush 40. Therefore, the longitudinal length of the brush housing 71 is longer than the length of the brush 40. The brush spring 50 is held by being sandwiched between the rear end surface 40b of the brush 40 and the rear end of the brush housing 71. The cover plate 120 covers not only the brush 40 but also the brush spring 50.

[0076] As described above, the brush holder 70 covers the opening 60a of the frame 60. Therefore, the brush holder 70 covers the rotor 20 housed in the frame 60. Specifically, as shown in FIG. 2, the brush holder 70 covers the rotor core 22 to which the rotating shaft 21 is fixed. For this reason, as shown in FIGS. 3 to 5, the brush holder 70 is provided with a through-hole 72 for passing the rotating shaft 21 therethrough. The through-hole 72 is provided in the center of the brush holder 70. The opening shape of the through-hole 72 is circular. The center of the through-hole 72 coincides with the axis C of the rotating shaft 21.

[0077] 4 and 5, the brush holder 70 has an annular wall 73 that surrounds the through-hole 72. The annular wall 73 is formed on the inner surface of the brush holder 70 so as to protrude from the opening edge of the through-hole 72.

[0078] The annular wall 73 has portions with different heights. Specifically, the annular wall 73 has a first wall portion 731 and a second wall portion 732 that is shorter in height than the first wall portion 731. Two first wall portions 731 and two second wall portions 732 are provided. One of the two first wall portions 731 (the first wall portion 731 on the power terminal 100 side) is sandwiched between two second wall portions 732. The other of the two first wall portions 731 forms part of the inner side wall of the recessed portion 70a that serves as the reservoir tank.

[0079] The second wall portion 732 is formed continuously with the step portion 714 formed on the first side wall 711 that constitutes the brush storage portion 71. In other words, the second wall portion 732 and the step portion 714 are formed integrally. The upper surface of the second wall portion 732 and the step surface 714a of the step portion 714 are flush with each other. The height of the second wall portion 732 and the height of the step surface 714a of the step portion 714 are the same.

[0080] The annular wall 73 further has a third wall portion 733. The height of the third wall portion 733 is lower than the height of the first wall portion 731. The height of the third wall portion 733 is higher than the height of the second wall portion 732. The third wall portion 733 is formed continuously with the second side wall 712 that constitutes the brush storage portion 71.

[0081] The front portion of the brush housing 71 is connected to the annular wall 73. The brush housing 71 and the annular wall 73 are integrally formed. Therefore, a brush opening 71a of the brush housing 71 is provided in the annular wall 73. Specifically, the brush opening 71a is provided in the third wall portion 733. The second wall portion 732, which has the lowest height, is provided in the vicinity of this brush opening 71a.

[0082] The brush holder 70 has ribs 74. The ribs 74 are formed on the inner surface of the brush holder 70. The ribs 74 are formed in a convex shape so as to protrude from the inner surface of the brush holder 70. The ribs 74 are formed in an elongated shape. The ribs 74 extend outward from the through holes 72. The ribs 74 are formed in a linear shape. The ribs 74 extend in a direction perpendicular to the rotation shaft 21 (i.e., in the radial direction).

[0083] As will be described later, a portion of the rib 74 functions to guide the pigtail wires 45. Therefore, two ribs 74 are formed for each of the two pigtail wires 45. Specifically, each of the two ribs 74 extends from near the center of a corresponding one of the two choke coils 110 toward the center of the through hole 72 (the axis C of the rotating shaft 21). Each rib 74 has a rectangular cross-sectional shape in a plane perpendicular to the longitudinal direction. Therefore, the upper surface of each rib 74 is flat. The number of ribs 74 is not limited to two, and may be one, or three or more. The multiple ribs 74 are formed radially from the through hole 72.

[0084] Each rib 74 has an inclined portion 741 with an inclined upper surface. Specifically, the inclined portion 741 has an inclined surface 741a whose height gradually increases toward the through-hole 72 (rotation shaft 21).

[0085] Each rib 74 is connected to the second wall portion 732 of the annular wall 73. The inclined portion 741 of the rib 74 is formed on the portion of the rib 74 on the through-hole 72 side. The inclined portion 741 of the rib 74 is formed continuously with the second wall portion 732 of the annular wall 73. In other words, the inclined portion 741 and the second wall portion 732 are formed integrally. The inclined surface 741a of the inclined portion 741 is inclined so that the height increases toward the upper surface of the second wall portion 732. The maximum height of the inclined surface 741a of the inclined portion 741 is the same as the height of the second wall portion 732.

[0086] The connection portion CP, where the second end 45b of the pigtail wire 45 is connected to the choke coil 110, is located above the rib 74. Specifically, in a top view, the connection portion CP is located outside the inclined portion 741. However, the rib 74 and the connection portion CP are not in contact with each other. In other words, there is a small gap between the connection portion CP and the rib 74. The connection portion CP is spaced apart from the upper surface of the rib 74.

[0087] The connection portion CP does not have to be located above the rib 74. In other words, the connection portion CP may be located above a part of the inner surface of the brush holder 70 other than the rib 74. There may be no gap between the connection portion CP and the rib 74. In other words, the connection portion CP may be in contact with the rib 74.

[0088] The thickness of the plate-shaped base portion (plate) of the brush holder 70 is thin. Therefore, the ribs 74 also function as reinforcing ribs for improving the strength of the brush holder 70. In other words, the ribs 74 are formed as a result of partially recessing the inner surface of the brush holder 70 in order to reduce the thickness of the base portion of the brush holder 70.

[0089] In the brush holder 70 configured as described above, one or more guide portions (pigtail wire guide portions) are provided on the inner surface of the brush holder 70 to guide the pigtail wire 45 when the pigtail wire 45 moves as the brush 40 wears. The pigtail wire guide portions are intended to ensure that the pigtail wire 45, which moves in accordance with the sliding of the brush 40 due to wear of the brush 40, moves in a constant manner. Specifically, the pigtail wire guide portions smooth the movement of the pigtail wire 45.

[0090] The brush holder 70 has a sloped portion 741 formed on the rib 74 as a first guide portion, which is one of the pigtail wire guide portions. The brush holder 70 has a stepped portion 714 formed on the first side wall 711 constituting the brush storage portion 71 as a second guide portion, which is one of the pigtail wire guide portions. The brush holder 70 has a second wall portion 732 formed on the annular wall 73 as a third guide portion, which is one of the pigtail wire guide portions.

[0091] Next, the function and effect of the pigtail wire guide portion provided on the brush holder 70 will be described in comparison with a motor of a comparative example with reference to FIGS.

[0092] Fig. 6 is a perspective view of a brush holder 70X in a comparative example electric motor, as viewed from the inner surface. Fig. 7 is a plan view of the brush holder 70X in a motor using the brush holder 70X in Fig. 6 , as viewed from the inner surface, for illustrating the movement of the pigtail wire 45 when the brush 40 wears and slides. Fig. 8 is an enlarged cross-sectional view of the brush holder 70X and the brush 40 in a motor using the brush holder 70X in Fig. 6 , for illustrating the movement of the pigtail wire 45 when the brush wears and slides. Fig. 9 is a plan view of the brush holder 70 in a motor 1 according to the embodiment, as viewed from the inner surface, for illustrating the movement of the pigtail wire 45 when the brush 40 wears and slides. Fig. 10 is an enlarged cross-sectional view of the brush holder 70 and the brush 40 in a motor 1 according to the embodiment, for illustrating the movement of the pigtail wire 45 when the brush 40 wears and slides.

[0093] 6, in the brush holder 70X of the electric motor of the comparative example, similarly to the brush holder 70 of the present embodiment, a brush 40, a pigtail wire 45, a brush spring 50, a power terminal 100, and a choke coil 110 are arranged. One end of the pigtail wire 45 is connected to a side surface of the brush 40. The other end of the pigtail wire 45 is connected and fixed to the choke coil 110.

[0094] 6, the brush holder 70X of the comparative example has a brush storage section 71X that stores the brushes 40, similar to the brush holder 70 of the present embodiment. However, the brush storage section 71X of the brush holder 70X of the comparative example is different from the brush storage section 71 of the brush holder 70 of the present embodiment. The first side wall 711X that constitutes the brush storage section 71X of the brush holder 70X of the comparative example does not have a step portion 714 formed thereon.

[0095] In the brush housing 71X of the brush holder 70X of the comparative example, similar to the brush housing 71 of the present embodiment, the first side wall 711X has a low-back portion 713 that is lower in height than the second side wall 712. Therefore, also in the brush holder 70X of the comparative example, the pigtail wire 45 connected to the side surface of the brush 40 is drawn out passing over the low-back portion 713.

[0096] The brush holder 70X of the comparative example has an annular wall 73X, similar to the brush holder 70 of the present embodiment. However, the annular wall 73X of the brush holder 70X of the comparative example is different from the annular wall 73 of the brush holder 70 of the present embodiment. The annular wall 73X of the brush holder 70X of the comparative example does not have a second wall portion 732. Specifically, the annular wall 73X of the brush holder 70X of the comparative example has only the first wall portion 731 and the third wall portion 733 provided on the annular wall 73 of the brush holder 70 of the present embodiment.

[0097] The brush holder 70 of the present embodiment is formed with ribs 74, but the brush holder 70X of the comparative example is not formed with a structure corresponding to the ribs 74.

[0098] In a comparative example electric motor using a brush holder 70X having such a configuration, as the brush 40 wears out as the motor is driven from a state before the brush 40 wears out as shown in Fig. 7(a), the rear end surface of the brush 40 approaches the commutator (rotating shaft) as shown in Fig. 7(b). At this time, the pigtail wire 45 connected to the brush 40 is pulled by the brush 40 and moves toward the commutator (inward). Specifically, as shown in Fig. 7(b), the pigtail wire 45 moves toward the commutator, with the connection point CP where the pigtail wire 45 and the choke coil 110 are connected serving as a fixed end.

[0099] In this case, the length of the pigtail wire 45 does not change. Therefore, the shape of the pigtail wire 45 changes as it moves toward the commutator. For example, as shown in FIG. 7B, part or all of the pigtail wire 45 may be curved so as to be convex inward (toward the commutator), or conversely, so as to be convex outward. Alternatively, as shown in FIG. 8, part or all of the pigtail wire 45 may be curved so as to be convex upward in the thickness direction of the brush holder 70X, or so as to be convex downward in the thickness direction of the brush holder 70X.

[0100] Moreover, the pigtail wire 45 is a braided wire or a stranded wire. Therefore, as shown in Figures 7 and 8, not only the shape but also the thickness may change as the pigtail wire 45 moves. For example, the thickness of the pigtail wire 45 may increase in some areas as the pigtail wire 45 moves.

[0101] As described above, the inner surface of the brush holder 70X is formed with an uneven structure including the brush storage portion 71X, the annular wall 73X, etc. Therefore, as shown in Figures 7 and 8, when the pigtail wire 45 moves toward the commutator while changing in shape and thickness as the brush 40 wears, the pigtail wire 45 may get caught on the uneven structure of the brush holder 70X, causing interference between the pigtail wire 45 and the uneven structure of the brush holder 70X.

[0102] For example, the pigtail wire 45 may come into contact with the wall surface of the first side wall 711X that constitutes the brush storage section 71X, with the choke coil 110, or, in the final stages of wear of the brush 40, with the annular wall 73X, or with other uneven structures formed on the brush holder 70X, causing interference.

[0103] As a result, in an electric motor using the brush holder 70X of the comparative example, unintended sliding loss may occur in the brush 40 connected to the pigtail wire 45, and the force (pressing pressure) of the brush 40 pressing against the commutator due to the spring elasticity of the brush spring 50 may decrease. In particular, when the brush 40 is in its final stage of wear, the pigtail wire 45 is likely to interfere with the uneven structure of the brush holder 70X, which may reduce the pressing force of the brush 40 against the commutator. This may result in poor electrical continuity between the brush 40 and the commutator, even though the effective wear portion of the brush 40 remains. In other words, an electric motor using the brush holder 70X of the comparative example may lose its function as an electric motor and have a shortened lifespan.

[0104] In contrast, in the electric motor 1 according to this embodiment, the brush holder 70 is provided with one or more guide portions that guide the pigtail wire 45 when the pigtail wire 45 moves as the brush 40 wears.

[0105] With this configuration, when the brush 40 wears from the state before wear shown in Figure 9(a) to the state shown in Figure 9(b), the pigtail wire 45 moves toward the commutator, with the connection part CP where the pigtail wire 45 and the choke coil 110 are connected as the fixed end, as shown in Figure 9(b).The pigtail wire 45 is guided by the guide part provided on the brush holder 70 and deforms while moving with a constant movement.

[0106] Specifically, in the brush holder 70 of this embodiment, a first guide portion, which is one of the guide portions, is provided on the rib 74. Specifically, the first guide portion provided on the rib 74 is an inclined portion 741 having an inclined surface 741a whose height gradually increases toward the through hole 72. The connection portion CP, where the pigtail wire 45 and the choke coil 110 are connected, is located outside the inclined portion 741 and above the rib 74.

[0107] In this case, even if the shape or thickness of the pigtail wire 45 changes when the pigtail wire 45 moves toward the commutator with the connection portion CP as a fixed end, the pigtail wire 45 moves in a constant motion while being guided along the inclined surface 741 a of the inclined portion 741 (first guide portion), which is the upper surface of the rib 74, without getting caught on the side surface of the rib 74. In other words, the inclined surface 741 a of the inclined portion 741 is a guide surface that guides the pigtail wire 45.

[0108] Moreover, in this embodiment, the rib 74 and the second wall portion 732 of the annular wall 73 are formed continuously. The maximum height of the inclined surface 741 a of the inclined portion 741 is the same as the height of the second wall portion 732 of the annular wall 73.

[0109] With this configuration, the pigtail wire 45 is guided along the inclined surface 741 a of the inclined portion 741 and moves toward the commutator. Even if the pigtail wire 45 goes beyond the inclined surface 741 a, the pigtail wire 45 moves to the upper surface of the second wall portion 732. This prevents the pigtail wire 45 from getting caught on the annular wall 73.

[0110] In the brush holder 70 of the present embodiment, a second guide portion, which is another of the guide portions, is provided in the brush housing portion 71. Specifically, the second guide portion provided in the brush housing portion 71 is provided in the first side wall 711 of the pair of first side walls 711 and second side walls 712 that constitute the brush housing portion 71. In the present embodiment, the second guide portion provided in the first side wall 711 is a step portion 714 provided on the outer side surface of the first side wall 711.

[0111] In this case, even if the shape or thickness of the pigtail wire 45 changes when the pigtail wire 45 moves toward the commutator due to wear of the brush 40, the pigtail wire 45 moves in a constant manner, guided by the step portion 714 (second guide portion) of the first side wall 711, as shown in Fig. 10. This prevents the pigtail wire 45 from interfering with the brush storage portion 71.

[0112] Moreover, in this embodiment, the first side wall 711 and the second wall portion 732 are formed continuously. The height of a step surface 714 a, which is one step lower than the step portion 714 formed on the first side wall 711, is the same as the height of the second wall portion 732 of the annular wall 73.

[0113] With this configuration, the pigtail wire 45, which is guided along the step portion 714 of the first side wall 711 and moves beyond the step portion 714, moves onto the upper surface of the second wall portion 732. Therefore, the pigtail wire 45 can be prevented from getting caught on the annular wall 73.

[0114] In the brush holder 70 of the present embodiment, a third guide portion, which is yet another guide portion, is provided on the annular wall 73. Specifically, the third guide portion provided on the annular wall 73 is a second wall portion 732 that exists near the brush opening 71 a of the brush storage portion 71.

[0115] In this case, even if the shape or thickness of the pigtail wire 45 changes as the brush 40 wears and the pigtail wire 45 moves toward the commutator, and a portion of the pigtail wire 45 reaches the annular wall 73, the pigtail wire 45 is guided by the second wall portion 732 (third guide portion) of the annular wall 73. This prevents the pigtail wire 45 from hitting or getting caught on the tall first wall portion 731. This prevents the pigtail wire 45 from interfering with the annular wall 73.

[0116] In this way, in the electric motor 1 of this embodiment, when the pigtail wire 45 moves toward the commutator 30 as the brush 40 wears, it is guided using at least one of one or more guide portions (first guide portion, second guide portion, third guide portion) provided on the brush holder 70.

[0117] 9 and 10, the pigtail wire 45 moves toward the commutator while maintaining a constant shape. This prevents interference between the pigtail wire 45 and the uneven structure of the brush holder 70. As a result, a reduction in the pressing force of the brush 40 against the commutator 30 can be prevented. This prevents poor conduction between the brush 40 and the commutator 30 and other problems. This prevents a reduction in the pressing force of the brush 40 against the commutator 30, thereby preventing a shortened lifespan of the electric motor 1.

[0118] As described above, the electric motor 1 of this embodiment comprises a rotor 20 having a rotating shaft 21 extending in the axial direction, a commutator 30 attached to the rotating shaft 21, brushes 40 in contact with the commutator 30, a brush holder 70 having a through hole 72 through which the rotating shaft 21 passes and a brush storage section 71 for storing the brush 40, and a conductive wire corresponding to the pigtail wire 45 having one end connected to the brush 40, and the brush holder 70 is provided with one or more guide sections for guiding the conductive wire as it moves as the brush 40 wears.

[0119] This makes it possible to prevent a decrease in the pressing pressure of the brushes 40 against the commutator 30. Therefore, it is possible to prevent a decrease in the life of the electric motor 1.

[0120] (Modification) The electric motor according to the present disclosure has been described above based on the embodiment, but the present disclosure is not limited to the above embodiment.

[0121] For example, in the above embodiment, a pigtail wire is used as an example of the conductive wire connected to the brush 40. However, the conductive wire connected to the brush 40 is not limited to a pigtail wire. For example, the conductive wire connected to the brush 40 may be an electric wire such as a vinyl wire. However, the thickness of a pigtail wire is easily deformed. For this reason, the guide portion according to the present disclosure is more effective when a pigtail wire is used as the conductive wire connected to the brush 40.

[0122] The electric motor 1 in the above embodiment includes the choke coil 110. However, this is not limiting. That is, the electric motor 1 does not necessarily have to include the choke coil 110. In this case, the second end 45b of the pigtail wire 45 may be directly connected to the power supply terminal 100 or may be connected to another conductive component connected to the power supply terminal 100. In either case, when the pigtail wire 45 moves toward the commutator due to wear of the brush 40, the second end 45b of the pigtail wire 45 becomes the fixed end.

[0123] 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 stator core.

[0124] In the above embodiment, the electric motor 1 is 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 devices, not limited to electrical devices mounted on automobiles. For example, the electric motor 1 may be used in household electrical devices, industrial devices, power tools, etc.

[0125] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that a person skilled in the art would conceive, or forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the spirit of the present disclosure.

[0126] The electric motor according to the present disclosure can be used in various products in which an electric motor is installed, such as automobiles.

[0127] REFERENCE SIGNS LIST 1 electric motor 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 40a front end surface 40b rear end surface 45 pigtail wire 45a first end 45b second end 50 brush spring 60 frame 60a opening 61 bearing holding portion 70 brush holder 70a recess 70b step portion 70c terminal arrangement portion 70d coil arrangement portion 71 brush storage portion 71a brush opening 72 through hole 73 annular wall 74 rib 81 first bearing 82 second bearing 90 seal member 100 power terminal 110 choke coil 120 Cover plate 711 First side wall 712 Second side wall 713 Low back portion 714 Step portion (second guide portion) 714a Step surface 731 First wall portion 732 Second wall portion (third guide portion) 733 Third wall portion 741 Inclined portion (first guide portion) 741a Inclined surface CP Connection portion

Claims

1. A rotor having a rotation axis extending in an axial direction; A commutator attached to the rotating shaft; A brush in contact with the commutator; a brush holder having a through hole through which the rotating shaft passes and a brush storage portion for storing the brush; a conductive wire having one end connected to the brush; the brush holder is provided with one or more guide portions that guide the conductive wire when the conductive wire moves as the brush wears; Electric motor.

2. The brush holder has a rib extending in a direction perpendicular to the axial direction, The rib has a first guide portion as one of the guide portions.

2. The electric motor according to claim 1.

3. The first guide portion is an inclined portion having an inclined surface whose height gradually increases toward the through hole.

3. The electric motor according to claim 2.

4. The brush storage section has a pair of side walls that sandwich the brush, One of the pair of side walls has a second guide portion as one of the guide portions. The electric motor according to any one of claims 1 to 3.

5. The second guide portion is a step portion provided on an outer side surface of one of the pair of side walls.

5. The electric motor according to claim 4.

6. The brush holder has an annular wall surrounding the through hole, The annular wall is formed with a brush opening for exposing a front end surface of the brush housed in the brush housing portion, The annular wall has a first wall portion and a second wall portion having a height shorter than that of the first wall portion, The second wall portion is provided in the vicinity of the brush opening as a third guide portion, which is one of the guide portions. The electric motor according to any one of claims 1 to 3.

7. The height of the second wall portion is the same as the maximum height of the inclined surface of the rib provided on the inner surface of the brush holder.

7. The electric motor according to claim 6.

8. The height of the second wall portion is the same as the height of a step surface that is one step lower than a step portion formed on an outer surface of one of a pair of side walls that constitute the brush storage portion.

7. The electric motor according to claim 6.

9. a power supply terminal and a choke coil inserted in a current path between the power supply terminal and the brush are disposed on the brush holder; The other end of the conductive wire is connected to the choke coil. The electric motor according to any one of claims 1 to 3.

10. the other end of the conductive wire and the choke coil are fixed by welding.

10. The electric motor according to claim 9.

11. a connection portion at which the other end of the conductive wire and the choke coil are connected is located above a rib provided on the brush holder; 10. The electric motor according to claim 9.

12. The one end of the conductive wire is fixed to a side surface of the brush. The electric motor according to any one of claims 1 to 3.

13. The conductive wire is a pigtail wire. The electric motor according to any one of claims 1 to 3.