Electric motor

Abstract

This electric motor comprises: a rotor having a rotary shaft that extends in an axial direction in which an axis extends; a commutator attached to the rotary shaft; a brush that contacts the commutator; a brush spring that presses the brush against the commutator; and a brush box that surrounds the brush. The brush spring is a constant load spring having a spiral part around which a belt-like wire material is wound. The brush is subjected to an elastic force so as to be advanced toward the commutator side by the constant load spring, and includes a front end part in contact with the commutator and a rear end part in contact with the spiral part. The constant load spring is arranged such that with respect to the rotary shaft, the central axis of the spiral part is aligned with the axis of the rotary shaft. When the height of the brush in the axial direction is HB and the width of the brush is WB, WB < HB. The brush box has a top plate part covering the brush. The top plate part has a first wall part protruding toward the bottom part side of the brush box. The first wall part faces the brush with a gap therebetween in the width direction of the brush.

Description

electric motor

[0001] The present disclosure relates to electric motors.

[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 mounted on vehicles, etc. For example, electric motors are used in two-wheeled or four-wheeled vehicles to drive cooling fans that cool the radiators or batteries.

[0003] Known electric motors include brushed motors (commutator motors) that use brushes and brushless motors that do not use brushes. Of these, brushed 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 that contact the commutator.

[0004] In brush motors, brush springs are used to press the brushes against the commutator. The brush springs apply a spring load (pressing force) to the brushes by utilizing the elastic force generated by their spring resilience. Conventionally, coil springs or torsion springs have been used as brush springs in brush motors.

[0005] However, when a coil spring or torsion spring is used as the brush spring, the spring load applied to the brush by the brush spring is not constant but gradually decreases as the brush wears. This results in a large difference between the pressure (initial pressure) before the brush wears and the pressure (final pressure) when the motor reaches the end of its life due to brush wear. Therefore, when using a coil spring or torsion spring, it is possible to set the initial pressure high to ensure a certain level of final pressure. However, doing so increases the friction between the brush and commutator during rotor rotation in the initial stage, resulting in increased brush sliding loss.

[0006] In brushed motors, brush wear determines the motor's lifespan. Specifically, the lifespan of the brushes due to wear determines the motor's lifespan. Brush wear can be broadly divided into two causes: electrical wear caused by sparks (commutation sparks), and mechanical wear caused by the sliding of the brush against the commutator. The brush is pressed against the commutator by the pressing force of the brush spring. However, if this pressing force is too high, mechanical wear increases, and if the pressing force is too low, the brush will bounce, inducing sparks and increasing electrical wear.

[0007] Therefore, a conventional technique has been proposed in which a constant force spring, whose spring load does not change with brush wear (stroke), is used as the brush spring. The use of a constant force spring can suppress excessive mechanical and electrical wear. For example, Patent Document 1 discloses an electric motor that uses a spiral spring having a spiral portion formed by winding a strip-shaped wire as a constant force spring, and that can apply a constant spring load to the brush by bringing the spiral portion of the spiral spring into contact with the rear end surface of the brush.

[0008] However, in a brushed electric motor that uses a constant force spring as a brush spring, it is difficult to achieve both high output and compactness while preventing the constant force spring from shifting from its predetermined position.

[0009] Japanese Unexamined Patent Publication No. 118987 / 1987

[0010] The present disclosure has been made to solve these problems, and aims to provide an electric motor that uses a constant force spring as a brush spring, and that can achieve both high output and compactness while preventing the brush spring from shifting from a predetermined position.

[0011] In order to achieve the above object, one aspect of an electric motor according to the present disclosure includes a rotor having a rotating shaft extending in an axial direction of an axis, a commutator attached to the rotating shaft, brushes in contact with the commutator, brush springs that press the brushes against the commutator, and a brush box that surrounds the brushes, wherein the brush springs are constant force springs having a spiral portion around which a strip-shaped wire is wound, the brushes having a height in the axial direction and a width in the circumferential direction of the rotor, and the brushes are subjected to an elastic force by the constant force spring so as to move towards the commutator, and include a front end in contact with the commutator and a rear end in contact with the spiral portion, the constant force springs are arranged such that a central axis of the spiral portion is oriented along the axis of the rotating shaft, and the height of the brushes is set to H Ｂ and the width of the brush is W Ｂ Then, W Ｂ <H Ｂ The brush box has a top plate portion that covers the brush, and the top plate portion has a first wall portion that protrudes toward the bottom side of the brush box, and the first wall portion faces the brush with a gap in the width direction of the brush.

[0012] Another aspect of the electric motor according to the present disclosure is an electric motor including a rotor having a rotating shaft extending in an axial direction in which an axis extends, a commutator attached to the rotating shaft, brushes in contact with the commutator, brush springs that press the brushes against the commutator, and a brush box that surrounds the brushes, wherein the brush springs are constant force springs having spiral portions around which strip-shaped wire is wound, and the brushes have a height in the axial direction and a width in the circumferential direction of the rotor, and are elastically moved toward the commutator by the constant force spring. and includes a front end in contact with the commutator and a rear end in contact with the spiral portion, the constant force spring is arranged with respect to the rotation shaft so that the central axis of the spiral portion is oriented along the axis of the rotation shaft, the rear end of the brush is provided with a contact surface with which a part of the spiral portion contacts, and a protruding portion that protrudes rearward from the contact surface and contacts another part of the spiral portion, the protruding portion being provided closer to the side of the pair of sides of the brush to which the pigtail wire is connected.

[0013] According to the present disclosure, in an electric motor that uses a constant force spring as a brush spring, it is possible to achieve both high output and compactness while preventing the brush spring from shifting from a predetermined position.

[0014] FIG. 1 is a perspective view of an electric motor according to a first embodiment, as viewed from above. FIG. 2 is a perspective view of the electric motor according to the first embodiment, as viewed from below. FIG. 3 is a cross-sectional view of the electric motor according to the first embodiment, cut along a plane passing through the axis of the rotating shaft and the brushes. FIG. 4 is an exploded perspective view of the electric motor according to the first embodiment. FIG. 5 is an exploded perspective view of the brush holder and various components arranged in the brush holder shown in FIG. 4. FIG. 6 is a plan view of FIG. 4 with the cover plate removed. FIG. 7 is an enlarged view of region VII surrounded by the dashed line in FIG. 6. FIG. 8 is a perspective view of the cover plate, as viewed from above. FIG. 9 is a perspective view of the cover plate, as viewed from below. FIG. 10 is a cross-sectional view taken along line X-X in FIG. 6. FIG. 11 is a diagram illustrating the positional relationship between the brush, brush spring, and cover plate in the brush holder in the electric motor according to the first embodiment. FIG. 12 is a diagram illustrating the relationship between the brush, brush spring, and brush box in an electric motor of a comparative example. FIG. 13 is a diagram for explaining the movement of the brush spring in the electric motor of the comparative example. Fig. 14 is an enlarged plan view showing a part of an electric motor according to embodiment 2. Fig. 15 is an enlarged plan view showing a part of an electric motor according to a modification of embodiment 2. Fig. 16A is a diagram showing the structure of a brush box of an electric motor according to modification 1. Fig. 16B is a diagram showing brushes and brush springs in an electric motor according to modification 1. Fig. 17A is a diagram showing the structure of a brush box of an electric motor according to modification 2. Fig. 17B is a diagram showing brushes and brush springs in an electric motor according to modification 2.

[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] In this specification and the drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. The X-axis and Y-axis are perpendicular to each other and perpendicular to the Z-axis. In this embodiment, the Z-axis direction is the direction in which the axis C of the rotation shaft 21 extends.

[0017] Each drawing is a schematic diagram and is not necessarily a precise illustration. In all drawings, substantially the same components are denoted by the same reference numerals, and redundant explanations will be omitted or simplified.

[0018] In this embodiment, the radial direction of the stator 10 and the rotor 20 is referred to as the "radial direction," and the rotation direction of the rotor 20 is referred to as the "circumferential direction." In other words, the direction spreading from the axis C of the rotating shaft 21 as the center is the "radial direction," and the direction going around the axis C of the rotating shaft 21 as the center is the "circumferential direction." Therefore, the "radial direction" is a direction perpendicular to the direction of the axis C of the rotating shaft 21 (also simply referred to as the "axial direction"). In this specification, the terms "up" and "down" do not necessarily refer to the up direction (vertically upward) and the down direction (vertically downward) in absolute spatial recognition.

[0019] (Embodiment 1) The overall configuration of an electric motor 1 according to embodiment 1 will be described with reference to Figures 1 to 7. Figure 1 is a perspective view of the electric motor 1 according to embodiment 1 as viewed from above. Figure 2 is a perspective view of the electric motor 1 according to embodiment 1 as viewed from below. Figure 3 is a cross-sectional view of the electric motor 1 according to embodiment 1 cut along a plane that passes through the axis C of the rotating shaft 21 and the brushes 40. Figure 4 is an exploded perspective view of the electric motor 1 according to embodiment 1. Figure 5 is an exploded perspective view of the brush holder 60 and various components arranged in the brush holder 60 shown in Figure 4. Figure 6 is a plan view of Figure 4 with the cover plate 70 removed. Figure 7 is an enlarged view of an area VII surrounded by a dashed line in Figure 6.

[0020] As shown in FIG. 3 , the electric motor 1 includes a stator 10 and a rotor 20 that rotates due to the magnetic force of the stator 10 .

[0021] The electric motor 1 is a brushed electric motor and further includes a commutator 30 attached to a rotating shaft 21 of the rotor 20, at least one brush 40 in contact with the commutator 30, a brush spring 50 for pressing the brush 40 against the commutator 30, a brush holder 60 for holding the brush 40, and a cover plate 70 for covering the brush 40.

[0022] As shown in Figures 3 and 4, the electric motor 1 further includes a power supply terminal 80 electrically connected to the brush 40, a first bearing 91 and a second bearing 92 that support the rotating shaft 21, a first bracket 101, and a second bracket 102.

[0023] 3, the electric motor 1 is a type of direct current motor (DC motor) that is driven by direct current. The electric motor 1 uses a magnet as the stator 10 and an armature having a coil 22 as the rotor 20.

[0024] In this embodiment, the electric motor 1 is a flat-type (flat type) brushed coreless motor (flat motor) mounted on a vehicle such as a two-wheeled or four-wheeled vehicle. Therefore, the stator 10 and the rotor 20 do not have a core (iron core), and the electric motor 1 has a thin and lightweight configuration overall. Specifically, the electric motor 1 is a small motor used in a cooling fan for a radiator in a vehicle. The outer diameter (diameter) φ of the electric motor 1 is 120 mm or less. For example, the outer diameter φ of the electric motor 1 is φ60 mm, φ70 mm, φ90 mm, or the like.

[0025] 1 and 2, a power supply line 2 for supplying power to the electric motor 1 is connected to the electric motor 1. The electric motor 1 is driven by power supplied from an external power source such as a battery. For example, the electric motor 1 is driven by an input voltage of DC 12 V supplied via the power supply line 2 connected to the external power source.

[0026] Hereinafter, each component of the electric motor 1 will be described in detail with reference to FIGS.

[0027] As shown in FIG. 3 , the stator 10 is disposed between the rotor 20 and the stator 10 via a small air gap. The stator 10 generates a magnetic force acting on the rotor 20. The stator 10 is configured to generate magnetic flux on the air gap surface with the rotor 20. The stator 10, together with the rotor 20, which is an armature, forms a magnetic circuit. Specifically, the stator 10 is substantially donut-shaped as a whole. The stator 10 is configured so that north and south poles alternate and exist evenly on the air gap surface with the rotor 20 along the circumferential direction of the rotating shaft 21. The stator 10 is a field magnet that generates magnetic flux for generating torque. The stator 10 is composed of multiple magnets. The magnets that make up the stator 10 are, for example, permanent magnets. The direction of the main magnetic flux generated by the stator 10 (magnets) is along the extension direction of the rotating shaft 21. The stator 10 is fixed to a first bracket 101.

[0028] The rotor 20 has a rotating shaft 21 and a coil 22. The rotor 20 is a coreless rotor that does not have a core.

[0029] The rotor 20 rotates around the axis C along which the rotating shaft 21 extends. The rotor 20 generates a magnetic force that acts on the stator 10. The direction of the main magnetic flux generated by the rotor 20 is along the axis C along which the rotating shaft 21 extends.

[0030] The rotor 20 is disposed opposite the stator 10. The rotor 20 faces the stator 10 in the direction of the axis C along which the rotating shaft 21 extends. Specifically, the coil 22 of the rotor 20 and the stator 10 face each other in the direction of the axis C along which the rotating shaft 21 extends. In other words, the coil 22 and the stator 10 are aligned in the direction of the axis C of the rotating shaft 21.

[0031] The rotating shaft 21 is a shaft having an axis C. The rotating shaft 21 is a long, rod-shaped member. As an example, the rotating shaft 21 is a metal rod made of a metal material such as SUS (Steel Use Stainless Steel). The axis C included in the rotating shaft 21 serves as the center of rotation when the rotor 20 rotates. The longitudinal direction of the rotating shaft 21, i.e., the direction in which the rotating shaft 21 extends (extension direction), is the direction of the axis C.

[0032] The rotating shaft 21 is supported by a first bearing 91 and a second bearing 92. Specifically, a first end 21a, which is one end of the rotating shaft 21, is supported by the first bearing 91. On the other hand, a second end 21b, which is the other end of the rotating shaft 21, is supported by the second bearing 92. The rotating shaft 21 is rotatably supported by the first bearing 91 and the second bearing 92. As an example, the first bearing 91 and the second bearing 92 are bearings such as ball bearings.

[0033] The first end 21a of the rotating shaft 21 is the end on the output side (output shaft). The first end 21a protrudes from the first bracket 101 and the first bearing 91. A load such as a rotary fan is attached to the first end 21a. The electric motor 1 with a rotary fan attached to the rotating shaft 21 can be used as, for example, a cooling fan or an electric blower. The second end 21b of the rotating shaft 21 is the end on the counter-output side (counter-output shaft). The second end 21b does not protrude from the second bracket 102 or the second bearing 92.

[0034] The first bearing 91 is held by the first bracket 101. Specifically, the first bearing 91 is fixed to a recess provided in the first bracket 101. The second bearing 92 is held by the brush holder 60. Specifically, the second bearing 92 is fixed to a recess provided in the brush holder 60.

[0035] The first bracket 101 and the second bracket 102 are made of, for example, a metal material. For example, the first bracket 101 and the second bracket 102 are made of an iron-based material such as cold-rolled steel plate (SPC (Steel Plate Cold) material) or a metal such as aluminum. The first bracket 101 and the second bracket 102 form a housing. The stator 10 and the rotor 20 are arranged in this housing.

[0036] As shown in Figures 1 and 2, the first bracket 101 is an outer shell member of the electric motor 1. The first bracket 101 is formed in a cylindrical shape with a bottom and a cylindrical side wall. The magnets that make up the stator 10 are fixed to the bottom of the first bracket 101. The coils 22 of the rotor 20 are surrounded by the side wall of the first bracket 101.

[0037] The second bracket 102 is arranged to cover the brush holder 60. Specifically, the second bracket 102 is arranged to cover the opening of the brush holder 60. The second bracket 102 has a flat plate shape. In other words, the second bracket 102 is a flat plate-shaped cover that is arranged to cover the opening of the brush holder 60. The second bracket 102 is arranged between the first bracket 101 and the brush holder 60. Specifically, the second bracket 102 is sandwiched between the first bracket 101 and the brush holder 60.

[0038] The material of the first bracket 101 and the second bracket 102 is not limited to a metal material and may be a resin material. From the viewpoint of suppressing noise generated from the electric motor 1, it is preferable that the first bracket 101 and the second bracket 102 are made of a metal material. Specifically, the first bracket 101 and the second bracket 102 are made of a metal plate. The first bracket 101 is formed into a predetermined three-dimensional shape by performing a predetermined press process or the like on the metal plate. The second bracket 102 is a flat, planar metal plate.

[0039] The coils 22 of the rotor 20 shown in Fig. 3 are wound coils. The rotor 20 has a plurality of coils 22. Each of the plurality of coils 22 is an armature winding made of electric wire. The plurality of coils 22 are wound so as to generate a magnetic force acting on the stator 10 when a current flows through them. The direction of the main magnetic flux generated by each coil 22 is along the axis C along which the rotating shaft 21 extends. Specifically, each of the plurality of coils 22 is wound in a flat shape. The coil surfaces of the plurality of coils 22 are arranged in a position facing the direction along the axis C along which the rotating shaft 21 extends.

[0040] Each coil 22 is formed of an insulating-coated wire having a core wire made of a metal such as copper or aluminum and an insulating film coating the core wire. Each of the multiple coils 22 is a thin wound coil having a coil layer in which the insulating-coated wire is wound in a planar shape. Specifically, each of the multiple coils 22 is formed, for example, of one or more coil layers in which the insulating-coated wire is wound in a substantially fan-like shape in a planar view. The multiple coils 22 thus formed are arranged to surround the rotating shaft 21 when viewed from the direction of the axis C along which the rotating shaft 21 extends.

[0041] Each of the plurality of coils 22 is electrically connected to the commutator 30. Specifically, each of the plurality of coils 22 is electrically connected to one of the plurality of commutator segments 31 of the commutator 30. Therefore, a current flows through each of the plurality of coils 22 via the commutator segment 31 with which the brush 40 is in contact.

[0042] The multiple coils 22 are covered with molded resin 23. That is, the multiple coils 22 are resin-molded. Therefore, by being covered with the molded resin 23, the multiple coils 22 are molded integrally with the molded resin 23. The planar external shape of the molded resin 23 after molding the multiple coils 22 is circular. The molded resin 23 may be made of an insulating resin material such as phenolic resin or unsaturated polyester (bulk molding compound (BMC)). The molded resin 23 may be made of either a thermosetting resin or a thermoplastic resin.

[0043] In this way, the electric motor 1 is a coreless motor in which the rotor 20 does not have a core. In the electric motor 1, the multiple coils 22 of the rotor 20 are thin and molded with resin. This makes it possible to realize a flat, thin electric motor 1 with low inductance.

[0044] 3 , the commutator 30 is attached to the rotating shaft 21. Therefore, the commutator 30 rotates together with the rotating shaft 21 as the rotor 20 rotates. The commutator 30 is attached to the second end 21b of the rotating shaft 21. The commutator 30 attached to the rotating shaft 21 may be a part of the rotor 20.

[0045] The commutator 30 has a plurality of commutator bars 31 (commutator segments) arranged along the rotation direction of the rotating shaft 21. Specifically, the plurality of commutator bars 31 are arranged in an annular shape along the rotation direction of the rotating shaft 21 so as to surround the rotating shaft 21. Each commutator bar 31 is shaped as an elongated member extending in the longitudinal direction of the rotating shaft 21.

[0046] Each of the plurality of commutator segments 31 is a conductive terminal made of a metal material such as copper. The plurality of commutator segments 31 are electrically connected to the coils 22 of the rotor 20. The plurality of commutator segments 31 are arranged insulated and separated from one another. The plurality of commutator segments 31 are electrically connected by the coils 22 of the rotor 20.

[0047] As an example, the commutator 30 is a molded commutator, and is configured such that a plurality of commutator segments 31 are molded in the molded resin 23. In this case, the plurality of commutator segments 31 are embedded in the molded resin 23 so that their surfaces are exposed. The molded resin 23 is the commutator main body, and is a substantially cylindrical member having a through hole into which the rotating shaft 21 is inserted. The molded resin 23 is a resin molded body made of an insulating resin material, such as a thermosetting resin.

[0048] At least one brush 40 is in contact with the commutator 30. Specifically, a front end 41 of the brush 40 is in contact with the commutator segments 31 of the commutator 30. As the commutator 30 rotates due to the rotation of the rotary shaft 21, the brush 40 continues to come into contact with all of the commutator segments 31 in sequence.

[0049] As shown in FIGS. 3 and 5, the brush 40 includes a front end 41 and a rear end 42 opposite the front end 41 .

[0050] The front end 41 of the brush 40 is one end in the longitudinal direction of the brush 40 and is the tip end of the brush 40 on the rotating shaft 21 side (radially inner side). The front end 41 of the brush 40 contacts the commutator 30. The front end surface of the front end 41 is one end surface in the longitudinal direction of the brush 40 and contacts the commutator segments 31 of the commutator 30.

[0051] The rear end 42 of the brush 40 is the other end in the longitudinal direction of the brush 40 and is the tip end on the opposite side (radially outward) from the rotary shaft 21 side of the brush 40. The rear end 42 of the brush 40 contacts the spiral portion 51 of the brush spring 50. The rear end surface of the rear end 42 is the other end surface in the longitudinal direction of the brush 40 and contacts the spiral portion 51 of the brush spring 50.

[0052] The brushes 40 are power supply brushes for supplying power to the coils 22. Specifically, the brushes 40 supply power to the coils 22 by contacting the commutator segments 31 of the commutator 30. When the brushes 40 contact the commutator segments 31, the armature current supplied to the brushes 40 from the power supply terminals 80 flows to the coils 22 via the commutator segments 31.

[0053] As an example, the brush 40 is a conductive carbon brush made of carbon. The brush 40 is a long, substantially rectangular parallelepiped. In this case, the brush 40 is preferably a carbon brush containing a metal such as copper. This reduces the contact resistance between the brush 40 and the commutator segments 31. Such a brush 40 can be produced, for example, by crushing a mixture of graphite powder, copper powder, binder resin, and hardener, compression-molding the mixture into a rectangular parallelepiped, and then firing the mixture.

[0054] The cross-sectional shape of the brush 40 is substantially a vertically long rectangle. In other words, in the cross section of the brush 40, the height of the brush 40 is greater than the width of the brush 40. In other words, the width of the brush 40 is smaller than the height of the brush 40. In this way, the brush 40 has a narrow width. The height of the brush 40 is the dimension in the direction of the axis C of the rotating shaft 21. The width of the brush 40 is the dimension in the circumferential direction of the rotor 20. In other words, the width of the brush 40 is the dimension in the direction perpendicular to both the direction of the axis C of the rotating shaft 21 and the radial direction of the rotor 20.

[0055] A plurality of brushes 40 are provided. Specifically, as shown in Figures 4 and 5, two brushes 40 are provided in the electric motor 1. The two brushes 40 are arranged in a positional relationship that forms a "V" shape when viewed from the direction of the axis C of the rotating shaft 21. Specifically, the two brushes 40 are arranged at an interval of 60° along the rotation direction of the rotor 20.

[0056] An elastic force is applied to each brush 40 by the brush spring 50 so that the brush 40 moves toward the commutator 30. Specifically, each brush 40 receives a pressing force (spring load) from the brush spring 50 and is constantly in contact with the commutator segments 31 of the commutator 30. In other words, the brush 40 is pressed against the commutator 30 by the brush spring 50. In this way, the brush 40 is in sliding contact with the commutator 30 and receives a pressing force based on the elastic force of the brush spring 50. The brush 40 is arranged so that it can move in a direction (radial direction) intersecting the direction of the axis C along which the rotating shaft 21 extends due to wear with the commutator 30.

[0057] The number of brush springs 50 provided corresponds to the number of brushes 40. Since the electric motor 1 is provided with two brushes 40, it is also provided with two brush springs 50. The brushes 40 and the brush springs 50 are housed in a brush holder 60 and covered with a cover plate 70.

[0058] The brush spring 50 applies a pressure (spring pressure) to the brush 40 by means of its spring elastic force (spring restoring force), urging the brush 40 toward the commutator 30. In this embodiment, the brush spring 50 is a constant-load spring. Therefore, the spring load of the brush spring 50 does not change in response to wear (stroke) of the brush 40, and applies a uniform spring load to the brush 40 from the initial stage before the brush 40 begins to wear to the final stage when the brush 40 has worn and the motor 1 has reached the end of its life.

[0059] The brush spring 50, which is a constant force spring, is made of a strip-shaped wire material. As shown in Figures 5 to 7, the brush spring 50, which is a constant force spring, is a spiral spring having a spiral portion 51 (coil portion) in which a strip-shaped wire material is wound in a spiral shape. The brush spring 50, which is a constant force spring, is made of a single strip-shaped wire material made of a metal material such as a steel plate.

[0060] Specifically, brush spring 50, which is a constant force spring, is made of a long, strip-shaped metal plate. Spiral portion 51 of brush spring 50 is a portion in which the long, strip-shaped metal plate is wound in a spiral shape multiple times in only one direction. Pulling out one end of the wire from spiral portion 51 generates a force (spring restoring force) in brush spring 50 that causes the wire to return to its original spiral shape.

[0061] 6 and 7 , by bringing the spiral portion 51, in a state in which the wire is pulled out and a spring restoring force is applied, into contact with the rear end portion 42 of the brush 40, a pressing force (spring load) can be applied to the brush 40. In other words, the brush spring 50 applies a pressing force to the brush 40 by the spiral portion 51, pressing the brush 40 against the commutator 30.

[0062] Brush spring 50 is disposed so that the spiral portion is horizontally oriented relative to rotary shaft 21. In other words, brush spring 50 is disposed so that the central axis (spiral axis) of spiral portion 51 is oriented along the direction of axis C of rotary shaft 21. Specifically, the perpendicular to the spiral surface (coil surface) of spiral portion 51 is substantially perpendicular to axis C of rotary shaft 21.

[0063] 4 and 5, power is supplied to the brushes 40 from an external power supply located outside the electric motor 1. The external power supply is a power supply that exists outside the electric motor 1 and supplies a predetermined input voltage to the electric motor 1. In this embodiment, the external power supply is a DC power supply that supplies an input voltage of DC 12 V to the electric motor 1.

[0064] As shown in Figures 4 and 6, the brushes 40 are disposed in a brush holder 60. The brush holder 60 is a holding member that holds the brushes 40. The brush holder 60 holds not only the brushes 40, but also the brush springs 50, the cover plate 70, and the power terminals 80. As shown in Figures 1 to 3, the brush holder 60 is also an outer shell member that constitutes the outer shell of the electric motor 1. The brush holder 60 covers the second bracket 102 from the outside.

[0065] The brush holder 60 is made of an insulating resin material. In this embodiment, the brush holder 60 is a resin-molded product integrally formed from an insulating resin material. As an example, the resin material constituting the brush holder 60 is phenolic resin. However, the present invention is not limited to this.

[0066] As shown in Figures 3 and 6, the brush holder 60 has brush storage sections 61 in which the brushes 40 are stored. The brush storage sections 61 are brush cases that contain the brushes 40. The number of brush storage sections 61 corresponds to the number of brushes 40. As shown in Figure 6, the brush holder 60 has two brush storage sections 61. The two brush storage sections 61 are arranged in a positional relationship that forms a "V" shape when viewed from the direction of the axis C of the rotating shaft 21. Specifically, the two brush storage sections 61 are arranged at an interval of 60° along the rotation direction of the rotor 20.

[0067] Each brush housing 61 is elongated in a direction perpendicular to the axial center C of the rotary shaft 21 (i.e., in the radial direction) and has a rectangular concave cross-sectional shape. Specifically, as shown in FIG. 5 , the brush housing 61 has a bottom 61a and a pair of side walls 61b extending from the bottom 61a. That is, the bottom 61a and the pair of side walls 61b form a recess with a concave cross-sectional shape. The bottom 61a of the brush housing 61 supports the bottom surface of the brush 40. The pair of side walls 61b of the brush housing 61 sandwich the brush 40. The pair of side walls 61b respectively face a pair of side surfaces of the brush 40. While the pair of side walls 61b may be in contact with the side surfaces of the brush 40, it is preferable to provide a gap between the pair of side walls 61b and the side surfaces of the brush 40 to facilitate sliding of the brush 40 within the brush housing 61.

[0068] As shown in FIG. 3 , the brush storage section 61 accommodates the brush 40 and the brush spring 50. Therefore, the longitudinal length of the brush storage section 61 is longer than the length of the brush 40. Specifically, the spiral portion 51 of the brush spring 50 is disposed rearward of the rear end portion 42 of the brush 40. In other words, the spiral portion 51 is disposed in the brush storage section 61 so as to be located on the opposite side of the brush 40 from the side on which the commutator 30 is located within the brush storage section 61. As shown in FIG. 7 , the brush spring 50 is fixed to the brush spring 50 by a portion of a lead wire 52, which is a wire drawn from the spiral portion 51, being supported by the brush holder 60. Specifically, the lead wire 52 drawn from the spiral portion 51 passes beside the brush 40, is extended toward the commutator 30, and is fixed to a recess 61 c formed in the front of the brush storage section 61. More specifically, the bent portion formed at the tip of the lead wire 52 is engaged with the recess 61 c of the brush holder 60 , thereby fixing the lead wire 52 to the brush holder 60 .

[0069] The brush 40 stored in the brush storage section 61 slides within the brush storage section 61. Specifically, the brush 40 pressed against the brush spring 50 moves toward the commutator 30 within the brush storage section 61 due to a pressing force based on the elastic force of the brush spring 50 as the front end 41 of the brush 40 wears due to friction with the commutator segments 31. In other words, as the brush 40 wears, the rear end face of the rear end 42 of the brush 40 moves in a direction (radial direction) toward the axis C of the rotary shaft 21. As a result, the spiral portion 51 of the brush spring 50 in contact with the rear end 42 of the brush 40 also moves toward the axis C of the rotary shaft 21 together with the rear end 42 of the brush 40.

[0070] 3 and 4, a cover plate 70 is provided to cover the brush 40 stored in the brush storage section 61. The cover plate 70 is arranged to cover the brush storage section 61. The cover plate 70 covers not only the brush 40 but also the brush spring 50. The cover plate 70 covering the brush 40 may or may not be in contact with the upper surface of the brush 40. The cover plate 70 and the lead wire 52 of the brush spring 50 may or may not be in contact with each other. A gap exists between the cover plate 70 and the spiral portion 51 of the brush spring 50.

[0071] FIG. 8 is a perspective view of the cover plate 70 as viewed from above. FIG. 9 is a perspective view of the cover plate 70 as viewed from below. The cover plate 70 is a metal plate made of a metal material such as brass or stainless steel (SUS). In this embodiment, the cover plate 70 is made of a plate-shaped metal plate. For example, the cover plate 70 having the shape shown in FIGS. 8 and 9 can be obtained by subjecting a single metal plate punched into a predetermined shape to sheet metal processing such as bending or pressing. As shown in FIGS. 8 and 9 , the cover plate 70 has a cover portion 71, a wall portion 72, and legs 73.

[0072] The cover portion 71 is the main body (cover body) of the cover plate 70, and covers the brush 40. The cover portion 71 covers not only the brush 40 but also the brush spring 50. The cover portion 71 is formed in an elongated shape along the longitudinal direction of the brush 40. The cover portion 71 is arranged to cover the brush storage portion 61 of the brush holder 60.

[0073] The cover portion 71 is bent so as to have a step in the width direction of the cover portion 71. The cover portion 71 has a first plate portion 71a that is the upper portion of the step and a second plate portion 71b that is the lower portion of the step. As shown in FIG. 7 , the first plate portion 71a covers the upper surface of the brush 40. The second plate portion 71b, which is lower than the first plate portion 71a, is located closer to the brush spring 50 than the first plate portion 71a. The second plate portion 71b covers a portion of the brush spring 50. In the width direction of the cover portion 71, the width of the first plate portion 71a is longer than the width of the second plate portion 71b. However, this is not limited to this.

[0074] As shown in FIG. 7 , the second plate portion 71b of the cover portion 71 covers the lead wire 52 of the brush spring 50. The second plate portion 71b also covers a portion of the spiral portion 51. The second plate portion 71b is close to the lead wire 52 of the brush spring 50 and a portion of the spiral portion 51. This allows the brush spring 50 to abut against the second plate portion 71b when it tries to tilt, thereby preventing the brush spring 50 from tilting. Furthermore, since the brush spring 50 abuts against the second plate portion 71b when it tries to tilt, the brush spring 50 does not abut against the first plate portion 71a. In other words, the brush spring 50 does not come into contact with the first plate portion 71a.

[0075] The wall portion 72 is formed so as to protrude from a side end portion in the width direction of the cover portion 71. The wall portion 72 is erected on the cover portion 71. In this embodiment, the wall portion 72 protrudes from an end portion of the first plate portion 71a of the cover portion 71. The wall portion 72 also extends in the longitudinal direction of the cover portion 71. The wall portion 72 is formed by bending a portion of the metal plate that constitutes the cover plate 70. The wall portion 72 and the cover portion 71 are formed so as to have an L-shaped cross section.

[0076] The leg portions 73 are formed to protrude from the side edges in the width direction of the cover portion 71. The leg portions 73 are erected on the cover portion 71 and extend in a direction perpendicular to the main surface of the cover portion 71. The leg portions 73 protrude beyond the wall portions 72. The leg portions 73 are formed by bending a portion of the metal plate that constitutes the cover plate 70.

[0077] In this embodiment, three legs 73 are provided. One of the three legs 73 is provided on one side of the cover portion 71 on which the wall portion 72 is provided. Specifically, one leg 73 is provided on an end of the first plate portion 71 a of the cover portion 71. Two of the three legs 73 are provided on the other side of the cover portion 71. Specifically, two legs 73 are provided on ends of the second plate portion 71 b of the cover portion 71. The three legs 73 are inserted into three insertion holes 62 provided in the brush holder 60, respectively. Specifically, each leg 73 is press-fitted into a corresponding one of the insertion holes 62. The cover plate 70 is fixed to the brush holder 60 by press-fitting the legs 73 into the insertion holes 62.

[0078] Figure 10 is a cross-sectional view taken along line X-X in Figure 6. As shown in Figure 10, the brush 40 is surrounded by a brush housing portion 61 and a cover plate 70. In other words, the brush housing portion 61 and the cover plate 70 form a brush box BX that surrounds the brush 40. In other words, the brush box BX is made up of two parts: the brush housing portion 61 made of resin and the cover plate 70 made of metal.

[0079] The brush box BX surrounds the four sides of the brush 40 and stores the brush 40. Specifically, the brush 40 is surrounded by a bottom 61a and a pair of side walls 61b that constitute the brush storage section 61, and a cover plate 70.

[0080] The cover plate 70 covers not only the brush 40 but also the brush spring 50. Therefore, the brush box BX covers not only the brush 40 but also the brush spring 50. In other words, the brush spring 50 is stored in the brush box BX and is surrounded by the cover plate 70 and the bottom 61a and pair of side wall portions 61b that constitute the brush storage section 61.

[0081] The cover plate 70 that covers the brushes 40 is the top plate of the brush box BX. The wall 72 of the cover plate 70 is the first wall of the brush box BX. The bottom 61a of the brush storage section 61 is the bottom of the brush box BX. Of the pair of side walls 61b of the brush storage section 61, the side wall 61b from which the pigtail wire 45 is pulled out is the second wall of the brush box BX.

[0082] As shown in Figure 10, the wall 72 (first wall) of the cover plate 70 protrudes toward the bottom 61a of the brush storage section 61, which is the bottom of the brush box BX. Specifically, the wall 72, which is the first wall, protrudes toward the side wall 61b, which is the second wall of the pair of side walls 61b. A gap G exists between the wall 72 of the cover plate 70, which is the first wall, and the side wall 61b, which is the second wall. The pigtail wire 45 connected to the brush 40 is pulled out from the gap G.

[0083] The wall 72, which is the first wall of the brush box BX, faces the brush 40 with a gap in the width direction of the brush 40. Specifically, the wall 72 (first wall) faces the side of the pair of side surfaces of the brush 40 from which the pigtail wire 45 is pulled out.

[0084] The side wall 61b, which is the second wall of the brush box BX, also faces the side of the pair of side surfaces of the brush 40 from which the pigtail wire 45 is pulled out. The inner surface of the side wall 61b, which is the second wall, is close to the side surface of the brush 40.

[0085] In the cover plate 70, which is the top plate of the brush box BX, the first plate portion 71a of the cover portion 71 covers the upper surface of the brush 40. The second plate portion 71b of the cover portion 71 covers the lead wire 52 of the brush spring 50. The second plate portion 71b is located closer to the brush spring 50 than the first plate portion 71a (i.e., closer to the bottom portion 61a of the brush storage portion 61).

[0086] As shown in Figure 2, the brush holder 60 has a recess 63 formed in a concave shape on the outer surface side of the brush holder 60. The recess 63 is formed by providing an outwardly protruding wall portion 63a on the outer surface of the brush holder 60. A power supply terminal 80 is exposed in the recess 63. The power supply line 2 is connected to the power supply terminal 80. In other words, the power supply line 2 and the power supply terminal 80 are electrically and mechanically connected. The recess 63 is filled with an insulating member made of an insulating resin material.

[0087] The power supply terminals 80 receive power from an external power supply via the power supply line 2 as power supply power to be supplied to the brushes 40. Therefore, the power supply terminals 80 are electrically connected to the brushes 40. The power supply power supplied to the brushes 40 is then supplied to the coils 22 of the rotor 20. In this embodiment, the external power supply is a DC power supply, so the power supply terminals 80 receive a DC voltage as an input voltage via the power supply line 2. Therefore, two power supply terminals 80 are provided. One of the two power supply terminals 80 is a positive power supply terminal connected to the positive side of the DC power supply. The other of the two power supply terminals 80 is a negative power supply terminal connected to the negative side of the DC power supply. The two power supply terminals 80 are fixed to the brush holder 60.

[0088] As shown in FIG. 4 , the power supply terminal 80 and the brush 40 are electrically connected by a pigtail wire 45. The pigtail wire 45 is connected to one of a pair of side surfaces of the brush 40. The pigtail wire 45 is drawn out from the side surface of the brush 40. One end of the pigtail wire 45 is embedded in the side surface of the brush 40 and fixed to the brush 40. The other end of the pigtail wire 45 is connected to the power supply terminal 80. The pigtail wire 45 and the power supply terminal 80 are joined by, for example, soldering. When power is supplied from an external power supply to the power supply terminal 80 via the power supply line 2, a current is supplied to the brush 40 via the pigtail wire 45 connected to the power supply terminal 80.

[0089] In the electric motor 1 configured as described above, when power is supplied to the power supply terminals 80 via the power supply line 2, the power is supplied to the brushes 40 via the power supply terminals 80. As a result, an armature current (drive current) flows through the coils 22 via the commutator 30, which is in contact with the brushes 40, generating magnetic flux in the rotor 20 (coils 22). A magnetic force generated by the interaction between the magnetic flux generated in the rotor 20 and the magnetic flux generated by the stator 10 becomes torque that rotates the rotor 20. At this time, the direction of the current flowing through the coils 22 is switched depending on the positional relationship when the commutator segments 31 and the brushes 40 are in 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, and the rotor 20 rotates about the axis C of the rotating shaft 21.

[0090] 11 is a diagram showing the positional relationship between the brushes 40, brush springs 50, and cover plate 70 in the brush holder 60 in the electric motor 1 according to the first embodiment. The relationship between the brushes 40, brush springs 50, and brush box BX (brush storage section 61, cover plate 70) will be described in detail with reference to FIG.

[0091] As shown in FIG. 11, the height of the brush 40 in the direction of the axis C is H Ｂ and the width of the brush 40 is W Ｂ As mentioned above, the width of the brush 40 is smaller than the height of the brush 40. Therefore, WＢ <H Ｂ In this embodiment, the corners of the brush 40 are chamfered. Therefore, the width of the top and bottom surfaces of the brush 40 (excluding the chamfered portions) is W Ｂ１ Then, W Ｂ１ <W Ｂ If the corners of the brush 40 are not chamfered, W Ｂ１ =W Ｂ is.

[0092] Regarding the height dimension of the brush box BX (brush storage section 61), the height of the side wall section 61b, which is the second wall section, is H １ The height of the brush spring holding space, which is the space required to hold the spiral portion 51 of the brush spring 50, is H ２ The height of the first brush holding space, which is the space required to hold the brush 40, is H ３ The height of the second brush holding space, which is the space required to hold the brush 40, is H ４ In this case, the height H of the brush box BX (brush storage section 61) is H = H ２ +H ３ +H ４ These heights of the brush box BX are lengths in the direction of the axis C of the rotary shaft 21. In this embodiment, H ２ is the height from the lower spiral surface of the spiral portion 51 of the brush spring 50 to the inner surface of the second plate portion 71b of the cover plate 70. ３ is the height from the inner surface of the bottom 61a of the brush storage portion 61 to the lower spiral surface of the spiral portion 51 of the brush spring 50. ４ is the height from the inner surface of the second plate portion 71b of the cover plate 70 to the inner surface of the first plate portion 71a.

[0093] Regarding the width dimension of the brush box BX (brush storage section 61), the width of the brush holding space, which is the space for holding the brush 40, is W １ and the width of the space for holding the brush spring 50 is W ２ In this embodiment, W １ is the distance between the pair of side wall portions 61b in the brush storage portion 61. ２is the width of the side wall portion 61b on the side opposite to the side from which the pigtail wire 45 is drawn out, out of the pair of side wall portions 61b.

[0094] Regarding the brush spring 50, the height (spring width) of the spiral portion 51 is W Ｓ The outer diameter of the spiral portion 51 is D Ｓ (See FIGS. 16B and 17B, which will be described later).

[0095] The gap between the wall portion 72 (first wall portion) of the cover plate 70 and the brush 40 in the width direction of the brush 40 is denoted by K.

[0096] In this case, the electric motor 1 of the present embodiment satisfies the following relational expression.

[0097] ・H ２ >W Ｓ ・H ３ >H １ ・H ４ >0 (D Ｓ -W Ｂ ) / 2 < K < D Ｓ / 2・D Ｓ >W Ｂ ・W ２ <D Ｓ 12 and 13, the features of the electric motor 1 according to the present embodiment will be described, including the background to the development of the technology of the present disclosure. FIG. 12 is a diagram showing the relationship between the brush 40, the brush spring 50, and the brush box BX (brush storage section 61, cover plate 70X) in an electric motor 1X of a comparative example. FIG. 13 is a diagram for explaining the movement of the brush spring 50 in the electric motor 1X of the comparative example.

[0098] In a brushed motor, when attempting to achieve both high output and compactness, the current increases, resulting in increased brush wear. Therefore, increasing the cross-sectional area of ​​the brushes is considered to suppress brush wear. In this case, if the brush width (dimension in the direction of rotation of the motor) is increased to increase the cross-sectional area of ​​the brushes, the brushes come into greater contact with the commutator segments, resulting in a decrease in the torque constant, a decrease in motor efficiency, increased heat generation, and increased sparks. Therefore, in order to achieve both high output and compactness, it is advisable to narrow the brush width and increase the cross-sectional area of ​​the brushes. Specifically, as in the case of a motor 1X shown in FIG. 12, the width W of the brush 40 is increased. Ｂ The height H of the brush 40 Ｂ It is better to make it smaller than Ｂ <H Ｂ ).

[0099] In a high-speed brush motor, a certain amount of spring load is required from the brush spring to stabilize the contact between the commutator and the brush. Furthermore, in order to apply a constant spring load to the brush throughout the initial to final stages of brush wear, it is possible to use a constant-force spring as the brush spring 50, as in the motor 1X shown in FIG. 12 . However, when a constant-force spring is used as the brush spring 50, the cross section of the brush spring 50 becomes larger than when a coil spring is used as the brush spring 50. Therefore, if the brush spring 50, which is a constant-force spring, shifts from its predetermined position, the brush spring 50 may come into contact with components inside the motor, resulting in a loss of spring load, or the brush spring 50 may fall off, causing brush lock.

[0100] For example, if a constant force spring is used as the brush spring 50, as shown in Figure 13, the spiral portion 51 of the brush spring 50 that contacts the rear end of the brush 40 will follow different paths when the brush spring 50 is extended (when the brush 40 is assembled) and when the brush spring 50 is contracted (when the brush 40 is worn). As a result, the spiral portion 51 of the brush spring 50 may fall off toward the pigtail wire 45, as shown by the block arrow. If the electric motor 1 vibrates significantly during transportation or installation, the vibration may cause the brush spring 50 to jump up, causing the spiral portion 51 to climb over the rear end surface of the brush 40 and fall off. In particular, as described above, when the width W of the brush 40 is Ｂ The height H of the brush 40 Ｂ If we make it smaller than (W Ｂ <H Ｂ ), the width of the brush 40 becomes narrower, and the spiral portion 51 of the brush spring 50 becomes more likely to fall off.

[0101] At this time, the width W of the bottom surface of the brush 40 Ｂ１ and the height (spring width) W of the spiral portion 51 of the brush spring 50 Ｓ That is, W Ｂ１ ≒W Ｓ Or W Ｂ１ <W Ｓ and the width W of the brush 40 Ｂ is the height H of the brush 40 Ｂ becomes smaller than (W Ｂ <H Ｂ 12 and 13, the spiral portion 51 of the brush spring 50 cannot be installed vertically (in the direction of the axis C), and must be installed horizontally (in the direction of rotation).

[0102] Therefore, in order to achieve both high output and miniaturization of the brushed motor, the inventors of the present application have decided to set the width W of the brush 40. Ｂ The height H of the brush 40 Ｂ Make it smaller than (W Ｂ <H Ｂ ) and, even when the spiral portion 51 of the brush spring 50, which is a constant-load spring, is installed horizontally, the inventors have thoroughly studied measures that can prevent the spiral portion 51 of the brush spring 50 from falling off.

[0103] As a result, the inventors of the present invention discovered that this problem could be solved by devising the structure of the brush box BX.

[0104] Specifically, in the electric motor 1 according to this embodiment, a cover plate 70 constituting the top plate of the brush box BX is provided with a wall portion 72 (first wall portion) that protrudes toward the bottom side of the brush box BX and faces the brush 40 with a gap in the width direction of the brush 40.

[0105] With this configuration, the width W of the brush 40 Ｂ The height H of the brush 40 Ｂ Make it smaller than (W Ｂ <H Ｂ ), and even when the spiral portion 51 of the brush spring 50, which is a constant force spring, is installed horizontally, the spiral portion 51 of the brush spring 50 can be prevented from climbing over the rear end surface of the brush 40 and falling off. In other words, the wall portion 72 provided on the cover plate 70 (top plate portion) functions as a fall-off prevention wall that prevents the spiral portion 51 of the brush spring 50 from falling off. In this way, the electric motor 1 according to this embodiment can achieve both high output and compact size, while preventing the brush spring 50, which is a constant force spring, from shifting from its predetermined position.

[0106] At this time, the gap K between the wall portion 72 of the cover plate 70 and the brush 40 in the width direction of the brush 40 and the outer diameter D of the spiral portion of the brush spring 50 are Ｓ That is, K<D Ｓ It is preferable that the relational expression of / 2 is satisfied.

[0107] By satisfying this relational expression, the direction of the spring load applied from the center (coil center) of the spiral portion 51 of the brush spring 50 can be made perpendicular to the rear end surface of the brush 40. In other words, the spiral portion 51 of the brush spring 50 can apply a spring load perpendicular to the rear end surface of the brush 40. Therefore, the vector with which the brush spring 50 pushes the brush 40 can be made to be in the direction of travel of the brush 40. This prevents the spiral portion 51 from applying unnecessary force to the brush 40 that would tilt the brush 40, thereby stabilizing the sliding of the brush 40. D Ｓ >W Ｂ , K>(DＳ -W Ｂ It is even more preferable if the relational expression:

[0108] In the electric motor 1 according to the present embodiment, the height H １ , H ２ , H ３ , H ４ and the height W of the spiral portion 51 Ｓ Regarding the above, as mentioned above, H ２ >W Ｓ , H ３ >H １ , H ４ > 0.

[0109] By satisfying this relational expression, even if the spiral portion 51 of the brush spring 50 tilts and contracts while following the contact state with the brush 40, the spiral portion 51 of the brush spring 50 does not come into contact with parts inside the motor, thereby reducing loss of spring load.

[0110] In addition, in the electric motor 1 according to the present embodiment, as described above, W ２ <D Ｓ / 2 relationship is satisfied.

[0111] Since the pigtail wire 45 is pulled out from the brush 40 on one of the pair of side walls 61b of the brush storage section 61, there is no wall supporting the brush 40. Therefore, the width W of the side wall 61b on the side opposite to the side on which the pigtail wire 45 is pulled out is ２ and the outer diameter D of the spiral portion 51 of the brush spring 50. Ｓ And, W ２ <D Ｓ By setting the width of the brush spring 50 to 2 / 2, the center (coil center) of the spiral portion 51 of the brush spring 50 is contained within the width of the brush 40, and the direction of the spring load applied from the center of the spiral portion 51 of the brush spring 50 can be made perpendicular to the rear end surface of the brush 40. This makes it even more difficult for the spiral portion 51 to apply an unnecessary force to the brush 40 that would tilt the brush 40, making it possible to further stabilize the sliding of the brush 40.

[0112] Second Embodiment Next, an electric motor 1A according to a second embodiment will be described with reference to Fig. 14. Fig. 14 is an enlarged plan view showing a portion of the electric motor 1A according to the second embodiment.

[0113] The electric motor 1A of the present embodiment differs from the electric motor 1 of the first embodiment in the shape of the rear end portion 42 of the brush 40A. Specifically, as shown in FIG. 14 , in the electric motor 1A of the present embodiment, the rear end portion 42 of the brush 40A is provided with a contact surface 42a that contacts a portion of the spiral portion 51 of the brush spring 50, and a protruding portion 43 that protrudes rearward from the contact surface 42a and contacts another portion of the spiral portion 51. The protruding portion 43 is provided on one of the pair of side surfaces of the brush 40A closer to the side surface to which the pigtail wire 45 is connected. Specifically, the protruding portion 43 is provided on the end of the pair of side surfaces of the brush 40A that is closer to the side surface to which the pigtail wire 45 is connected (the end in the width direction of the brush 40A).

[0114] In the electric motor 1A of this embodiment as well, the cover plate 70 constituting the top plate portion of the brush box BX has a wall portion 72 facing the brushes 40A with a gap K therebetween.

[0115] With this configuration, the width W of the brush 40A Ｂ The height H of the brush 40A Ｂ Furthermore, even when the spiral portion 51 of the brush spring 50, which is a constant force spring, is installed horizontally, the spiral portion 51 of the brush spring 50 can be prevented from climbing over the rear end surface of the brush 40A and falling off. Therefore, it is possible to achieve both high output and compactness while preventing the brush spring 50, which is a constant force spring, from shifting from its predetermined position.

[0116] At this time, if the gap K between the wall portion 72 (anti-fall wall) and the brush 40A is narrow, the brush spring 50 may come into contact with the wall portion 72 of the cover plate 70, resulting in a loss of spring load or causing the brush spring 50 and the cover plate 70 to stick together due to micro-sliding wear.

[0117] In contrast, in the electric motor 1A of the present embodiment, the protrusion 43 is provided on the rear end 42 of the brush 40A, which prevents the spiral portion 51 of the brush spring 50 from shifting toward the wall portion 72 of the cover plate 70. Therefore, contact between the spiral portion 51 of the brush spring 50 and the wall portion 72 of the cover plate 70 can be prevented.

[0118] The protrusion 43 provided on the rear end 42 of the brush 40A has the function of preventing the spiral portion 51 of the brush spring 50 from climbing over the rear end surface of the brush 40 and falling off. In other words, the protrusion 43 of the brush 40A also functions as a fall-off prevention wall that prevents the spiral portion 51 of the brush spring 50 from falling off, similar to the wall portion 72 of the cover plate 70. Therefore, the electric motor 1A can achieve a double safety mechanism by using two fall-off prevention walls, the protrusion 43 of the brush 40A and the wall portion 72 of the cover plate 70.

[0119] Because the protruding portions 43 of the brushes 40A function as fall-off prevention walls, the electric motor 1A of this embodiment does not require the wall portions 72 to be provided on the cover plate 70. In other words, in this embodiment, the cover plate 70 may be changed to a cover plate 70X shown in FIG.

[0120] In addition, in the electric motor 1A according to the present embodiment, the inner side surface (the spiral portion 51 side) of the protrusion 43 provided at the rear end portion 42 of the brush 40A is a curved surface. However, this is not limited to this. Fig. 15 is an enlarged plan view showing a portion of an electric motor 1B according to a modification of the second embodiment. For example, as in the electric motor 1B shown in Fig. 15, the inner side surface (the spiral portion 51 side) of the protrusion 43B provided at the rear end portion 42 of the brush 40B may be a flat, inclined surface.

[0121] With this configuration, even if the spiral portion 51 of the brush spring 50 bounces up due to vibration or the like, it is returned to its original position by the inclined surface of the protruding portion 43B, thereby further preventing the brush spring 50 from shifting from its predetermined position.

[0122] (Modification 1) Next, an electric motor 1C according to Modification 1 will be described with reference to Fig. 16A and Fig. 16B. Fig. 16A is a diagram showing the structure of the brush box BX of the electric motor 1C according to Modification 1. Fig. 16B is a diagram showing the brush 40C and the brush spring 50 in the electric motor 1C according to Modification 1.

[0123] The electric motor 1C of this modification differs from the electric motor 1 of the first embodiment in the shape of a cover plate 70C of the brush box BX and the shape of the brushes 40C.

[0124] Specifically, as shown in FIGS. 16A and 16B , in the electric motor 1C of this modification, a groove 44 into which the spiral portion 51 of the brush spring 50 fits is formed in the rear end 42 of the brush 40C. This prevents the spiral portion 51 of the brush spring 50 from tilting. In the first embodiment, the second plate portion 71b of the cover portion 71 is formed by providing a step in the cover portion 71 of the cover plate 70. Even if the spiral portion 51 tilts, the second plate portion 71b of the cover portion 71 prevents the spiral portion 51 from coming into contact with components inside the electric motor 1C, thereby reducing loss of spring load. In this modification, the brush 40C prevents the spiral portion 51 from tilting. Therefore, the cover portion 71 of the cover plate 70 does not need to have a step. For this reason, this modification uses a cover plate 70C having a cover portion 71C without a step and a wall portion 72.

[0125] In the electric motor 1C configured as described above, the brush box BX, which is composed of the cover plate 70C and the brush housing 61, has a bottom portion, which is the bottom portion 61a of the brush housing 61, and a side wall portion 61b (the side wall portion 61b from which the pigtail wire 45 is drawn out) which stands on the bottom portion and faces the side surface of the brush 40C. The pigtail wire 45 connected to the brush 40C is drawn out from a gap G between the wall portion 72 (first wall portion) of the cover plate 70C and the side wall portion 61b which is the second wall portion. As shown in FIG. 16A, the height of the side wall portion 61b which is the second wall portion is set to H. １ The height from the lower spiral surface of the spiral portion 51 of the brush spring 50 to the inner surface of the cover plate 70, which is the top plate portion, is H ２The height from the inner surface of the bottom 61a of the brush storage section 61, which is the bottom of the brush box BX, to the lower spiral surface of the spiral section 51 is H ３ The height of the spiral portion 51 is W Ｓ and the height from the groove 44 of the brush 40C to the upper surface of the brush 40 is H Ｂ１ The height from the bottom surface of the brush 40 to the groove 44 of the brush 40C is H Ｂ２ Then, H ２ >W Ｓ , H ３ >H Ｂ２ >H １ , H Ｂ１ > 0.

[0126] As described above, in the electric motor 1C of this modified example, the cover plate 70C constituting the top plate portion of the brush box BX also has the wall portion 72 facing the brushes 40C with the gap K therebetween.

[0127] With this configuration, the width W of the brush 40C Ｂ The height H of the brush 40C Ｂ Furthermore, even when the spiral portion 51 of the brush spring 50, which is a constant force spring, is installed horizontally, the spiral portion 51 of the brush spring 50 can be prevented from climbing over the rear end surface of the brush 40C and falling off. Therefore, in this modified example, it is possible to achieve both high output and compactness while preventing the brush spring 50, which is a constant force spring, from shifting from its predetermined position.

[0128] (Modification 2) Next, an electric motor 1D according to Modification 2 will be described with reference to Fig. 17A and Fig. 17B. Fig. 17A is a diagram showing the structure of the brush box BX of the electric motor 1D according to Modification 2. Fig. 17B is a diagram showing the brush 40D and the brush spring 50 in the electric motor 1D according to Modification 2.

[0129] The electric motor 1D of this modification differs from the electric motor 1 of the first embodiment in the shape of the brush box BX and the shape of the brushes 40D.

[0130] Specifically, the brush box BX in the first embodiment is composed of two components: a brush storage section 61 and a cover plate 70. In contrast, as shown in FIG. 17A , the brush box BX in this modification is composed only of a brush storage section 61D. In addition to a bottom 61a and a pair of side walls 61b, the brush storage section 61D in this modification has an upper section 61d that serves as the top plate of the brush box BX. The upper section 61d (top plate) has a first plate section 61d1 that covers the top surface of the brush 40D, a second plate section 61d2 that is located closer to the spiral section 51 than the first plate section 61d1 and covers the upper spiral surface of the spiral section 51, and a third plate section 61d3 that covers the side surface on the top side of the brush 40D. The upper section 61d, which serves as the top plate, has a wall section 61d4 that protrudes toward the bottom section 61a. The wall 61d4 is a first wall that faces the brush 40D across a gap K in the width direction of the brush 40D, similar to the wall 72 of the cover plate 70 in the above embodiment. The pigtail wire 45 connected to the brush 40D is pulled out from a gap G between the wall 61d4, which is the first wall, and the side wall 61b, which is the second wall (the side wall 61b from which the pigtail wire 45 is pulled out, of the pair of side walls 61b).

[0131] In this manner, in the electric motor 1D of this modified example as well, the upper portion 61d of the brush storage portion 61 constituting the top plate portion of the brush box BX has a wall portion 61d4 facing the brush 40D with a gap K therebetween.

[0132] With this configuration, the width W of the brush 40D Ｂ The height H of the brush 40D Ｂ Furthermore, even when the spiral portion 51 of the brush spring 50, which is a constant force spring, is installed horizontally, the spiral portion 51 of the brush spring 50 can be prevented from climbing over the rear end surface of the brush 40D and falling off. Therefore, in this modified example, it is possible to achieve both high output and compactness while preventing the brush spring 50, which is a constant force spring, from shifting from its predetermined position.

[0133] As shown in FIG. 17B , in the electric motor 1D, the rear end 42 of the brush 40D is provided with a protrusion 43D that protrudes rearward and contacts the spiral portion 51. The protrusion 43D is provided closer to the side of the pair of sides of the brush 40 to which the pigtail wire 45 is connected. The side of the protrusion 43 facing the spiral portion 51 is a flat, inclined surface. The protrusion 43D is provided over the entire rear end 42 of the brush 40D. The inclined surface of the protrusion 43D forms the rear end surface of the brush 40D. Therefore, the spiral portion 51 of the brush spring 50 contacts only the inclined surface of the protrusion 43D, which forms the rear end surface of the brush 40D. This allows the spiral portion 51 of the brush spring 50 to apply a spring load to the rear end surface of the brush 40 in a diagonal direction opposite to the pigtail wire 45 side. In other words, the vector by which the brush spring 50 pushes the brush 40 can be in a diagonal direction opposite to the pigtail wire 45 side. Therefore, in the electric motor 1D of this modified example, the spiral portion 51 can be further prevented from falling off toward the pigtail wire 45 side.

[0134] In this way, the electric motor 1D in this modification has a structure in which the brush box BX is formed by integral molding using a slide mold and supports the upper and lower surfaces of the brush 40D. Specifically, as shown in FIG. 17A, the height of the side wall portion 61b, which is the second wall portion, is set to H １ and the height from the lower spiral surface of the spiral portion 51 to the inner surface of the second plate portion 61d2 of the upper portion 61d is H ２ The height from the inner surface of the bottom 61a of the brush box BX to the lower spiral surface of the spiral part 51 is H ３ The height from the inner surface of the second plate portion 61d2 to the inner surface of the first plate portion 61d1 in the upper portion 61d is H ４ The height from the inner surface of the third plate portion 61d3 to the inner surface of the first plate portion 61d1 in the upper portion 61d is H ５ The height of the spiral portion 51 is W Ｓ Then, H ２ >W Ｓ , H ３ >H １ , H ４ >H ５ The following relation is satisfied.

[0135] (Other Modifications) The electric motor according to the present disclosure has been described above based on the embodiment and modifications, but the present disclosure is not limited to the above embodiment and modifications.

[0136] For example, in the above embodiment, the two brushes 40 are arranged in a positional relationship that forms a V shape when viewed from above, but this is not limited to this. As an example, the two brushes 40 may be arranged in a straight line facing each other with the commutator 30 in between. In other words, the two brushes 40 may be arranged at 180° intervals along the rotation direction of the rotor 20. The number of brushes 40 is not limited to two.

[0137] In the above embodiment, the rotating shaft 21 is supported by two bearings, the first bearing 91 and the second bearing 92. However, this is not limiting. Specifically, the rotating shaft 21 may be supported by a single bearing.

[0138] Furthermore, in the above embodiment, the electric motor 1 is a coreless motor in which the stator 10 and the rotor 20 do not have cores. However, this is not limiting. For example, the electric motor 1 may be an electric motor in which the stator 10 and the rotor 20 have cores. However, by using a coreless motor as in the above embodiment, it is possible to realize an electric motor 1 that has low inductance and is thin.

[0139] In the above embodiment, the stator 10 is composed of only permanent magnets. However, this is not limiting. For example, the stator 10 may be a stator composed of permanent magnets and an iron core, or an armature composed of a stator winding and an iron core without using permanent magnets.

[0140] In the above embodiment, the electric motor 1 is a flat motor having an outer size in which the thickness is smaller than the outer diameter. However, this is not limited to this. The technology of the present disclosure can also be applied to, for example, a cylindrical electric motor having a cylindrical housing having an outer size in which the thickness is larger than the outer diameter.

[0141] Furthermore, in the above embodiment, the direction of the main magnetic flux generated by the stator 10 and the rotor 20 is the direction in which the axis C of the rotating shaft 21 extends. However, this is not limited to this. Specifically, the direction of the main magnetic flux generated by the stator 10 and the rotor 20 may be a direction perpendicular to the direction in which the axis C of the rotating shaft 21 extends (the radial direction of rotation of the rotating shaft 21). For example, the technology disclosed herein may also be applied to an inner rotor type motor in which the rotor 20 is arranged inside the stator 10.

[0142] In the above embodiment, the electric motor 1 is a vehicle motor used in a vehicle. However, the present disclosure is not limited to this. The technology of the present disclosure can also be applied to electric motors used in various other electrical devices, such as electric motors used in electric blowers mounted on electric vacuum cleaners.

[0143] 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 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 multiple claims.

[0144] The technology disclosed herein can be widely used in electric motors and various products equipped with electric motors, including products in the electrical equipment field such as automobiles and the field of household electrical appliances.

[0145] REFERENCE SIGNS LIST 1, 1A, 1B, 1C, 1D, 1X Electric motor 2 Power supply line 10 Stator 20 Rotor 21 Rotating shaft 21a First end 21b Second end 22 Coil 23 Molded resin 30 Commutator 31 Commutator segment 40, 40A, 40B, 40C, 40D Brush 41 Front end 42 Rear end 42a Contact surface 43, 43B, 43D Projection 44 Groove 45 Pigtail wire 50 Brush spring 51 Spiral portion 52 Lead wire 60 Brush holder 61, 61D Brush storage portion 61a Bottom 61b Side wall portion 61c Recessed portion 61d Upper portion 61d1 First plate portion 61d2 Second plate portion 61d3 Third plate portion 61d4 Wall portion 62 Insertion hole 63 Recessed portion 63a Wall portion 70, 70C, 70X Cover plate 71, 71C Cover portion 71a First plate portion 71b Second plate portion 72 Wall portion 73 Leg portion 80 Power terminal 91 First bearing 92 Second bearing 101 First bracket 102 Second bracket BX Brush box

Claims

1. A rotor having a rotating shaft extending in an axial direction in which an axis extends, a commutator attached to the rotating shaft, brushes in contact with the commutator, brush springs that press the brushes against the commutator, and a brush box that surrounds the brushes, wherein the brush springs are constant force springs having a spiral portion around which a strip-shaped wire is wound, the brushes have a height in the axial direction and a width in the circumferential direction of the rotor, and the brushes are subjected to an elastic force by the constant force spring so as to move toward the commutator, and include a front end that contacts the commutator and a rear end that contacts the spiral portion, the constant force springs are arranged so that the central axis of the spiral portion is oriented along the axis of the rotating shaft, and the height of the brushes is H Ｂ and the width of the brush is W Ｂ Then, W Ｂ <H Ｂ the brush box has a top plate portion that covers the brushes, the top plate portion has a first wall portion that protrudes toward a bottom side of the brush box, and the first wall portion faces the brushes with a gap in the width direction of the brushes.

2. The gap is K, and the outer diameter of the spiral part is D. Ｓ Then, K<D Ｓ 2. The electric motor according to claim 1, wherein:

3. D Ｓ >W Ｂ , K>(D Ｓ -W Ｂ 3. The electric motor of claim 2, wherein:

4. The top plate portion has a first plate portion that covers the upper surface of the brush, and a second plate portion that is located closer to the brush spring than the first plate portion and covers a part of the brush spring, the brush box has a second wall portion that stands on the bottom and faces the side of the brush, the pigtail wire connected to the brush is drawn out from between the first wall portion and the second wall portion, and the height of the second wall portion is H １ and the height from the lower spiral surface of the spiral portion to the inner surface of the second plate portion is H ２ and the height from the inner surface of the bottom of the brush box to the lower spiral surface of the spiral part is H ３ and the height from the inner surface of the second plate portion to the inner surface of the first plate portion is H ４ and the height of the spiral portion in the axial direction is W Ｓ Then, H ２ >W Ｓ , H ３ >H １ , H ４ 2. The electric motor of claim 1, wherein:

5. A groove into which the spiral portion fits is formed at the rear end of the brush, the brush box has a bottom and a second wall portion standing on the bottom and facing the side of the brush, the pigtail wire connected to the brush is drawn out from between the first wall portion and the second wall portion, and the height of the second wall portion is H １ and the height from the lower spiral surface of the spiral portion to the inner surface of the top plate portion is H ２ and the height from the inner surface of the bottom of the brush box to the lower spiral surface of the spiral part is H ３ and the height of the spiral part is W Ｓ and the height from the groove to the top surface of the brush is H Ｂ１ The height from the bottom surface of the brush to the groove is H Ｂ２ Then, H ２ >W Ｓ , H ３ >H Ｂ２ >H １ , H Ｂ１ 2. The electric motor of claim 1, wherein:

6. An electric motor according to any one of claims 1 to 5, further comprising a brush holder having a brush storage section for storing the brushes, the brush box having the brush storage section and a cover plate that covers the brushes, and the top plate section being the cover plate.

7. The rear end of the brush is provided with a protruding portion that protrudes rearward and contacts the spiral portion, the protruding portion is provided on one of a pair of sides of the brush closer to the side to which the pigtail wire is connected, the side of the protruding portion facing the spiral portion is an inclined surface, the top plate portion has a first plate portion that covers the top surface of the brush, a second plate portion that is located closer to the spiral portion than the first plate portion and covers the upper spiral surface of the spiral portion, and a third plate portion that covers the side surface on the top surface side of the brush, the brush box has a second wall portion that stands on the bottom and faces the side of the brush, the pigtail wire connected to the brush is pulled out from between the first wall portion and the second wall portion, and the height of the second wall portion is H １ and the height from the lower spiral surface of the spiral portion to the inner surface of the second plate portion is H ２ and the height from the inner surface of the bottom of the brush box to the lower spiral surface of the spiral part is H ３ and the height from the inner surface of the second plate portion to the inner surface of the first plate portion is H ４ and the height from the inner surface of the third plate portion to the inner surface of the first plate portion is H ５ and the height of the spiral part is W Ｓ Then, H ２ >W Ｓ , H ３ >H １ , H ４ >H ５ The electric motor according to claim 1 , wherein:

8. An electric motor as described in claim 1, wherein the rear end of the brush is provided with a contact surface with which a part of the spiral portion comes into contact, and a protruding portion that protrudes rearward from the contact surface and comes into contact with another part of the spiral portion, and the protruding portion is provided on one of a pair of side surfaces of the brush closer to the side to which the pigtail wire is connected.

9. The electric motor according to claim 8, wherein the side surface of the protrusion facing the spiral portion is an inclined surface.

10. An electric motor according to any one of claims 1 to 5 and 7 to 9, wherein the first wall portion extends along the longitudinal direction of the brush.

11. A rotor having a rotating shaft extending in the axial direction of an axis, a commutator attached to the rotating shaft, a brush in contact with the commutator, a brush spring for pressing the brush against the commutator, and a brush box surrounding the brush, wherein the brush spring is a constant force spring having a spiral portion around which a strip-shaped wire is wound, the brush is subjected to an elastic force by the constant force spring so as to move toward the commutator, and includes a front end in contact with the commutator and a rear end in contact with the spiral portion, the constant force spring is arranged so that the central axis of the spiral portion is oriented along the axis of the rotating shaft, and the rear end of the brush is provided with a contact surface with which a part of the spiral portion contacts, and a protruding portion that protrudes rearward from the contact surface and contacts another part of the spiral portion, and the protruding portion is provided on one of a pair of side surfaces of the brush closer to the side to which the pigtail wire is connected. Electric motor.

12. The electric motor according to claim 11, wherein the side surface of the protrusion facing the spiral portion is an inclined surface.

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