electric motor

Abstract

The electric motor comprises: a rotor having a rotating shaft extending along a axial direction, the axial direction being the direction in which the rotating shaft extends axially; a commutator mounted on the rotating shaft; brushes in contact with the commutator; brush springs pressing the brushes against the commutator; and a brush housing surrounding the brushes. The brush springs are constant-force springs having a spiral portion formed by winding a strip of wire. The brushes are subjected to a spring force by the constant-force spring in a manner that propels them toward the commutator side, and include a front end in contact with the commutator and a rear end in contact with the spiral portion. The constant-force spring is configured relative to the rotating shaft such that the central axis of the spiral portion is aligned along the axial direction of the rotating shaft. When the height of the brush in the axial direction is set as H... B Set the width of the brush to W. B When W is satisfied B <H B The brush box has a top plate that covers the brush. The top plate has a first wall that protrudes toward the bottom side of the brush box. The first wall is spaced apart from the brush in the width direction of the brush.

Description

Technical Field

[0001] This disclosure relates to electric motors. Background Technology

[0002] Electric motors are widely used in household electrical appliances, such as electric vacuum cleaners, and also in electrical equipment installed in vehicles. For example, in two-wheeled or four-wheeled vehicles, electric motors are used to drive cooling fans that cool radiators or batteries.

[0003] As electric motors, brushed motors (commutator motors) that use brushes and brushless motors that do not use brushes are known. Among them, a brushed motor has a stator, a rotor that rotates by the magnetic force of the stator, a commutator mounted on the rotating shaft of the rotor, and brushes that are in contact with the commutator.

[0004] In brushed motors, brush springs are used to press the brushes against the commutator. The brush spring applies a spring load (pressing force) to the brushes using the elastic force generated by the spring's resilience. Traditionally, coil springs or torsion springs were used as brush springs in brushed motors.

[0005] However, when using helical or torsion springs as brush springs, the spring load applied by the brush spring to the brush is not constant, but gradually decreases as the brush wears. Therefore, the difference between the initial pressure before brush wear (initial pressure) and the final pressure when the motor reaches the end of its lifespan due to brush wear (final pressure) becomes larger. Thus, when using helical or torsion springs, a higher initial pressure is considered to ensure a certain final pressure. However, this increases the friction between the brush and the commutator during the initial stage of rotor rotation, leading to greater brush sliding losses.

[0006] In brushed motors, brush wear determines the motor's lifespan. Specifically, the lifespan of the brushes, determined by wear, becomes the motor's lifespan. The main causes of brush wear can be broadly categorized into two types: electrical wear caused by sparking (rectifier sparking) and mechanical wear caused by sliding between the brush and the commutator. The brushes are pressed against the commutator by pressure from the brush springs. However, when this pressure is high, mechanical wear increases; when the pressure is low, the brushes bounce and generate sparks, thus increasing electrical wear.

[0007] Therefore, in the past, a technique has been proposed to use a constant-force spring as the brush spring, where the spring load remains constant relative to the brush wear (stroke). By using a constant-force spring, excessive mechanical and electrical wear can be suppressed. For example, Patent Document 1 discloses an electric motor that uses a spiral spring with a spiral portion formed by winding a strip of wire into a spiral shape as a constant-force spring, in which the spiral portion of the spiral spring contacts the rear end face of the brush, thereby applying a constant spring load to the brush.

[0008] However, in brushed motors that use constant force springs as brush springs, it is difficult to suppress the constant force spring from deviating from its specified position while simultaneously achieving high output and miniaturization.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 61-118987 Summary of the Invention

[0012] This disclosure was made to solve such a problem. The purpose of this disclosure is to provide an electric motor that, in which a constant force spring is used as the brush spring, can suppress the brush spring from deviating from a specified position while achieving both high output and miniaturization.

[0013] To achieve the above objectives, a technical solution for an electric motor disclosed herein comprises: a rotor having a rotating shaft extending along an axial direction, the axial direction being the direction in which the rotating shaft extends axially; a commutator mounted on the rotating shaft; brushes contacting the commutator; brush springs pressing the brushes against the commutator; and a brush housing surrounding the brushes, the brush springs being constant force springs having a spiral portion formed by winding strip-shaped wires, the brushes having a height in the axial direction and a width in the circumferential direction of the rotor, being subjected to elastic force by the constant force spring in a manner that propels them toward the commutator side, and including a front end contacting the commutator and a rear end contacting the spiral portion, the constant force spring being configured relative to the rotating shaft such that the central axis of the spiral portion is aligned with the axial direction of the rotating shaft, when the height of the brush is set to H. B The width of the brush is set to W. B When W is satisfied B <H B The brush box has a top plate portion covering the brush, the top plate portion having a first wall portion protruding toward the bottom side of the brush box, the first wall portion being openly opposed to the brush in the direction of the width of the brush.

[0014] Another technical solution of the electric motor disclosed herein includes: a rotor having a rotating shaft extending along an axial direction, the axial direction being the direction in which the rotating shaft extends axially; a commutator mounted on the rotating shaft; brushes contacting the commutator; brush springs pressing the brushes against the commutator; and a brush housing surrounding the brushes, the brush springs being constant force springs having a spiral portion formed by winding strip-shaped wires, the brushes having height in the axial direction and width in the circumferential direction of the rotor, and being pressed by the constant force springs. The constant force spring is applied in a manner that moves toward the commutator side and includes a front end that contacts the commutator and a rear end that contacts the scroll portion. The constant force spring is configured relative to the rotation axis such that the central axis of the scroll portion is in the direction along the axis of the rotation axis. The rear end of the brush is provided with: a contact surface for partial contact of the scroll portion; and a protrusion that protrudes rearward from the contact surface and for another partial contact of the scroll portion. The protrusion is provided near the side of one of a pair of sides of the brush connected to the brush braid.

[0015] According to this disclosure, in an electric motor using a constant force spring as the brush spring, it is possible to suppress the brush spring from shifting from a specified position while achieving both high output and miniaturization. Attached Figure Description

[0016] Figure 1 This is a perspective view of the electric motor in Embodiment 1 viewed from above.

[0017] Figure 2 This is a perspective view of the electric motor in Embodiment 1 viewed from below.

[0018] Figure 3 This is a cross-sectional view of the motor of Embodiment 1 when cut with a plane passing through the axis of rotation and through the brush.

[0019] Figure 4 This is an exploded perspective view of the electric motor according to Embodiment 1.

[0020] Figure 5 yes Figure 4 An exploded perspective view of the brush holder and the various components disposed within it.

[0021] Figure 6 Is Figure 4 The top view shows the state of the device with the cover removed.

[0022] Figure 7 yes Figure 6 An enlarged view of region VII, which is enclosed by a dashed line.

[0023] Figure 8 This is a three-dimensional view of the cover plate viewed from above.

[0024] Figure 9 This is a three-dimensional view of the cover plate viewed from below.

[0025] Figure 10 yes Figure 6 A cross-sectional view at line XX.

[0026] Figure 11 This is a diagram showing the positional relationship between the brushes, brush springs, and cover plates in the brush holder of the electric motor in Embodiment 1.

[0027] Figure 12 This is a diagram showing the relationship between the brushes, brush springs, and brush box in a comparative example motor.

[0028] Figure 13 This diagram is used to illustrate the operation of the brush springs in the electric motor of the comparative example.

[0029] Figure 14 This is an enlarged top view showing a portion of the electric motor in Embodiment 2.

[0030] Figure 15 This is a partial enlarged top view of the electric motor in a modified example of Embodiment 2.

[0031] Figure 16A This is a diagram showing the structure of the brush box of the electric motor in Modified Example 1.

[0032] Figure 16B This is a diagram showing the brushes and brush springs in the electric motor of Variation Example 1.

[0033] Figure 17A This is a diagram showing the structure of the brush box of the electric motor in Modified Example 2.

[0034] Figure 17B This is a diagram showing the brushes and brush springs in the electric motor of Variation Example 2. Detailed Implementation

[0035] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are all specific examples of the present disclosure. Therefore, the numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, and connection methods shown in the following embodiments are examples and are not intended to limit the present disclosure. Therefore, the constituent elements in the following embodiments that are not described in the independent claims representing the highest-level concept of the present disclosure will be described as arbitrary constituent elements.

[0036] In this specification and accompanying drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional orthogonal coordinate system. The X-axis and Y-axis are mutually orthogonal and both orthogonal to the Z-axis. In this embodiment, the Z-axis direction is the direction in which the axis C of the rotation axis 21 extends.

[0037] Each figure is a schematic diagram and not necessarily a strict representation. In all figures, substantially identical structures are labeled with the same reference numerals, and repetitive descriptions are omitted or simplified.

[0038] In this embodiment, the radial direction of the stator 10 and rotor 20 is defined as "radial," and the rotational direction of the rotor 20 is defined as "circumferential." That is, the direction extending from the axis C of the rotation shaft 21 is "radial," and the direction surrounding the axis C of the rotation shaft 21 is "circumferential." Therefore, "radial" becomes a direction orthogonal to the axis C direction of the rotation shaft 21 (also simply referred to as the "axial direction"). In this specification, terms such as "up" and "down" do not necessarily refer to the absolute spatial orientation of the upward (vertical above) and downward (vertical below) directions.

[0039] (Implementation Method 1)

[0040] use Figures 1 to 7 The overall structure of the electric motor 1 in Embodiment 1 will be described. Figure 1 This is a perspective view of the motor 1 in Embodiment 1 as viewed from above. Figure 2 This is a perspective view of the motor 1 in Embodiment 1 as viewed from below. Figure 3 This is a cross-sectional view of the motor 1 of Embodiment 1 when cut by a plane passing through the axis C of the rotating shaft 21 and through the brush 40. Figure 4 This is an exploded perspective view of the electric motor 1 according to Embodiment 1. Figure 5 yes Figure 4 An exploded perspective view of the brush holder 60 and the various components disposed on the brush holder 60. Figure 6 Is Figure 4 The top view shows the state of the device with the cover plate 70 removed. Figure 7 yes Figure 6 An enlarged view of region VII, which is enclosed by a dashed line.

[0041] like Figure 3 As shown, the motor 1 has a stator 10 and a rotor 20 that rotates using the magnetic force of the stator 10.

[0042] The electric motor 1 is a brushed electric motor. The electric motor 1 also includes: a commutator 30 mounted on the 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.

[0043] like Figure 3 , Figure 4 As shown, the motor 1 also includes: a power terminal 80 electrically connected to the brush 40; a first bearing 91 and a second bearing 92 supporting the rotating shaft 21; a first bracket 101; and a second bracket 102.

[0044] like Figure 3 As shown, motor 1 is a DC motor (DC motor) driven by a direct current. In motor 1, a magnet is used as the stator 10, and an armature with coils 22 is used as the rotor 20.

[0045] In this embodiment, the electric motor 1 is a flat-type brushed coreless motor (flat motor) mounted in a two-wheeled or four-wheeled vehicle. Therefore, the stator 10 and rotor 20 do not have a core, resulting in an overall thin and lightweight structure for the electric motor 1. Specifically, the electric motor 1 is a small motor used in the cooling fan of a radiator in a vehicle. The outer diameter (φ) of the electric motor 1 is 120 mm or less. As an example, the outer diameter φ of the electric motor 1 is φ60 mm, φ70 mm, or φ90 mm, etc.

[0046] like Figure 1 and Figure 2 As shown, a power supply line 2 for supplying power to the motor 1 is connected to the motor 1. The motor 1 is driven by power supplied from an external power source such as a battery. For example, the motor 1 is driven by a DC 12V input voltage supplied via the power supply line 2 connected to an external power source.

[0047] The following is for reference Figures 1 to 7 The components of the electric motor 1 are described in detail.

[0048] like Figure 3As shown, the stator 10 is configured with a small air gap between it and the rotor 20. The stator 10 generates a magnetic force acting on the rotor 20. The stator 10 is configured to generate magnetic flux at the air gap surface that forms the air gap with the rotor 20. The stator 10 and the rotor 20, which serves as the armature, together form a magnetic circuit. Specifically, the stator 10 is substantially annular in shape. The stator 10 is configured to have alternating and equal N and S poles at the air gap surface that forms the air gap with the rotor 20 along the circumference of the rotation axis 21. The stator 10 is an excitation element that generates magnetic flux for generating torque. The stator 10 is composed of multiple magnets. The magnets constituting the stator 10 are, for example, permanent magnets. The direction of the main magnetic flux generated by the stator 10 (magnets) is the direction extending along the rotation axis 21. The stator 10 is fixed to the first bracket 101.

[0049] The rotor 20 has a rotating shaft 21 and a coil 22. The rotor 20 is a coreless rotor without a core.

[0050] The rotor 20 rotates around the axis C extending from the rotating shaft 21. The rotor 20 generates a magnetic force acting on the stator 10. The direction of the main magnetic flux generated by the rotor 20 is along the axis C, and the rotating shaft 21 extends along the axis C.

[0051] The rotor 20 is configured opposite to the stator 10. The rotor 20 is opposite to the stator 10 in the direction of the axis C extending from the rotation shaft 21. Specifically, the coil 22 of the rotor 20 is opposite to the stator 10 in the direction of the axis C extending from the rotation shaft 21. That is, the coil 22 and the stator 10 are arranged in the direction of the axis C of the rotation shaft 21.

[0052] The rotating shaft 21 is a shaft with a center C. The rotating shaft 21 is a long, rod-shaped component. For example, the rotating shaft 21 is a metal rod made of a metal material such as SUS (Steel Use Stainless). The center C of the rotating shaft 21 becomes the center of rotation when the rotor 20 rotates. The length direction of the rotating shaft 21, that is, the direction in which the rotating shaft 21 extends (the extension direction), is the direction of the center C.

[0053] The rotating shaft 21 is supported by a first bearing 91 and a second bearing 92. Specifically, one end of the rotating shaft 21, namely the first end 21a, is supported by the first bearing 91. On the other hand, the other end of the rotating shaft 21, namely the second end 21b, is supported by the second bearing 92. The rotating shaft 21 is supported by the first bearing 91 and the second bearing 92 to allow it to rotate freely. As an example, the first bearing 91 and the second bearing 92 are bearings such as ball bearings.

[0054] The first end 21a of the rotating shaft 21 is the output-side end (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 mounted on the first end 21a. The motor 1 with the rotary fan mounted on the rotating shaft 21 can be used, for example, as a cooling fan or an electric blower. Furthermore, the second end 21b of the rotating shaft 21 is the non-output-side end (non-output shaft). The second end 21b does not protrude from the second bracket 102 and the second bearing 92.

[0055] The first bearing 91 is held in 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 in the brush holder 60. Specifically, the second bearing 92 is fixed to a recess provided in the brush holder 60.

[0056] The first bracket 101 and the second bracket 102 are made of metal materials, for example. For instance, the first bracket 101 and the second bracket 102 are made of ferrous materials such as cold-rolled steel sheet (SPC (Steel Plate Cold) material) or metals such as aluminum. The first bracket 101 and the second bracket 102 form a housing. The stator 10 and the rotor 20 are disposed within this housing.

[0057] like Figure 1 and Figure 2 As shown, the first bracket 101 is the housing component of the electric motor 1. The first bracket 101 is formed into a bottomed cylindrical shape with a bottom and cylindrical sidewalls. The magnet constituting the stator 10 is fixed to the bottom of the first bracket 101. The coil 22 of the rotor 20 is surrounded by the sidewalls of the first bracket 101.

[0058] The second bracket 102 is configured to cover the brush holder 60. Specifically, the second bracket 102 is configured to cover the opening of the brush holder 60. The second bracket 102 is flat. That is, the second bracket 102 is a flat cover configured to cover the opening of the brush holder 60. The second bracket 102 is disposed between the first bracket 101 and the brush holder 60. Specifically, the second bracket 102 is held between the first bracket 101 and the brush holder 60.

[0059] The materials of the first bracket 101 and the second bracket 102 are not limited to metal, but may also be resin. From the viewpoint of suppressing noise generated from the electric motor 1, the first bracket 101 and the second bracket 102 are preferably made of metal. Specifically, the first bracket 101 and the second bracket 102 are made of metal plates. The first bracket 101 is formed into a predetermined three-dimensional shape by performing a predetermined stamping process or the like on the metal plate. The second bracket 102 is a flat, plate-shaped metal plate.

[0060] Figure 3The rotor 20 shown has coils 22, which are winding coils. The rotor 20 has multiple coils 22. Each coil 22 is an armature winding made of wire. The multiple coils 22 are wound in such a way that a magnetic force acting on the stator 10 is generated by the flow of current. The direction of the main magnetic flux generated by each coil 22 is along the axis C, and the rotation shaft 21 extends along the axis C. Specifically, the multiple coils 22 are each wound into a flat shape. The coil faces of the multiple coils 22 are arranged in an orientation facing the axis C, and the rotation shaft 21 extends along the axis C.

[0061] Each coil 22 is composed of an insulated wire having a core made of a metal such as copper or aluminum and an insulating film covering the core. Each coil 22 is a thin winding coil having a coil layer formed by winding the insulated wire into a planar shape. Specifically, each coil 22 is, for example, composed of one or more coil layers formed by winding the insulated wire into a substantially fan shape when viewed from above. The coils 22 thus configured are arranged to surround the rotation axis 21 when viewed along the axis C extending from the rotation axis 21.

[0062] Multiple coils 22 are electrically connected to the commutator 30. Specifically, the multiple coils 22 are electrically connected to any one of the multiple commutator segments 31 of the commutator 30. Therefore, current flows to the multiple coils 22 via the commutator segments 31 contacted by the brushes 40.

[0063] Multiple coils 22 are covered by molding resin 23. That is, multiple coils 22 are resin molded. Therefore, the multiple coils 22 are integrally formed with the molding resin 23 by being covered by the molding resin 23. The top view of the molding resin 23 after molding the multiple coils 22 is circular. The molding resin 23 can be, for example, an insulating resin material such as phenolic resin or unsaturated polyester (Bulk Molding Compound (BMC)). The molding resin 23 can be any of thermosetting resin and thermoplastic resin.

[0064] Thus, the motor 1 is a coreless motor in which the rotor 20 does not have a core. In the motor 1, the multiple coils 22 of the rotor 20 are thin and are molded in resin. As a result, a thin motor 1 with low inductance and a flat shape can be realized.

[0065] like Figure 3 As shown, the commutator 30 is mounted on the rotating shaft 21. Therefore, the commutator 30 rotates together with the rotating shaft 21 as the rotor 20 rotates. The commutator 30 is mounted on the second end 21b of the rotating shaft 21. The commutator 30 mounted on the rotating shaft 21 can also be a part of the rotor 20.

[0066] The commutator 30 has a plurality of commutator segments 31 arranged along the rotation direction of the rotation axis 21. Specifically, the plurality of commutator segments 31 are arranged in a ring around the rotation axis 21 in the rotation direction of the rotation axis 21. Each commutator segment 31 is a long strip-shaped member extending along the length direction of the rotation axis 21.

[0067] Each commutator segment 31 is a conductive terminal made of a metal material such as copper. The commutator segments 31 are electrically connected to the coils 22 of the rotor 20. The commutator segments 31 are arranged insulated and separate from each other. The commutator segments 31 are electrically connected to the coils 22 of the rotor 20.

[0068] As an example, the commutator 30 is a molded commutator, consisting of a plurality of commutator segments 31 molded from molding resin 23. In this case, the plurality of commutator segments 31 are embedded in the molding resin 23 with their surfaces exposed. The molding resin 23 is the commutator body, a substantial cylindrical component having a through hole for the insertion of the rotating shaft 21. The molding resin 23 is, for example, a resin molded body made of an insulating resin material such as a thermosetting resin.

[0069] At least one brush 40 is in contact with the commutator 30. Specifically, the front end 41 of the brush 40 is in contact with the commutator segment 31 of the commutator 30. As the commutator 30 rotates by the rotation of the rotating shaft 21, the brush 40 is in continuous contact with all the commutator segments 31 in sequence.

[0070] like Figure 3 and Figure 5 As shown, the brush 40 includes a front end portion 41 and a rear end portion 42 located on the side opposite to the front end portion 41.

[0071] The front end portion 41 of the brush 40 is one end of the brush 40 along its length, and is the top end of the brush 40 on the side (radially inward) near the rotating shaft 21. The front end portion 41 of the brush 40 contacts the commutator 30. The front end face of the front end portion 41 is one end face of the brush 40 along its length, and contacts the commutator segment 31 of the commutator 30.

[0072] The rear end portion 42 of the brush 40 is another end portion along the length of the brush 40, and is the top end portion of the brush 40 on the side opposite to the side of the rotating shaft 21 (radially outward). The rear end portion 42 of the brush 40 contacts the spiral portion 51 of the brush spring 50. The rear end face of the rear end portion 42 is another end face along the length of the brush 40, and contacts the spiral portion 51 of the brush spring 50.

[0073] Brush 40 is a power supply brush used to supply power to coil 22. Specifically, brush 40 supplies power to coil 22 by contacting commutator segments 31 of commutator 30. Through the contact between brush 40 and commutator segments 31, armature current supplied from power terminal 80 to brush 40 flows to coil 22 via commutator segments 31.

[0074] As an example, the brush 40 is a conductive carbon brush made of carbon. The brush 40 is a long, rectangular parallelepiped. In this case, the brush 40 is preferably a carbon brush containing metals such as copper. This reduces the contact resistance between the brush 40 and the commutator segment 31. Such a brush 40 can be manufactured, for example, by crushing and compressing a mixture obtained by mixing graphite powder, copper powder, binder resin, and curing agent into a rectangular parallelepiped and then firing it.

[0075] The cross-sectional shape of brush 40 is a longitudinally elongated, essentially rectangular shape. That is, in the cross-section of brush 40, the height of brush 40 is greater than the width of brush 40. In other words, the width of brush 40 is smaller than its height. Thus, brush 40 has a narrowed width shape. The height of brush 40 is its dimension along the axis C of the rotating shaft 21. The width of brush 40 is its dimension along the circumference of the rotor 20. That is, the width of brush 40 is its dimension in a direction orthogonal to both the axis C of the rotating shaft 21 and the radial direction of the rotor 10.

[0076] There are multiple brush 40 settings. Specifically, such as... Figure 4 and Figure 5 As shown, the motor 1 is provided with two brushes 40. The two brushes 40 are arranged in a figure-eight position when viewed from the axis C of the rotating shaft 21. Specifically, the two brushes 40 are arranged at a 60° interval along the rotation direction of the rotor 20.

[0077] Each brush 40 is spring-loaded by a brush spring 50 in a manner that propels it toward the commutator 30. Specifically, each brush 40 is subjected to a pressing force (spring load) from the brush spring 50, and is always in contact with the commutator segments 31 of the commutator 30. That is, the brush 40 is pressed against the commutator 30 by the brush spring 50. Thus, the brush 40 is in sliding contact with the commutator 30 due to the pressing force based on the spring force of the brush spring 50. The brush 40 is configured to be able to move in a direction (radial) intersecting the axis C extending from the rotation shaft 21 due to wear with the commutator 30.

[0078] The number of brush springs 50 is determined by the number of brushes 40. Since there are two brushes 40 in the motor 1, there are also two brush springs 50. The brushes 40 and brush springs 50 are housed in the brush holder 60 and covered by the cover plate 70.

[0079] The brush spring 50 applies pressure (spring pressure) to the brush 40 using its spring force (spring restoring force), exerting force on the brush 40 toward the commutator 30. In this embodiment, the brush spring 50 is a constant force spring. Therefore, the spring load of the brush spring 50 does not change relative to the wear (stroke) of the brush 40, and a uniform spring load is applied to the brush 40 from the initial stage before the brush 40 wears out to the end stage when the brush 40 wears out and the motor 1 reaches the end of its life.

[0080] The brush spring 50, acting as a constant force spring, is composed of a strip of wire. For example... Figures 5-7 As shown, the brush spring 50, which is a constant force spring, is a spiral spring having a spiral portion 51 (coil portion) formed by winding a strip of wire into a spiral shape. The brush spring 50, which is a constant force spring, is, for example, made of a strip of wire, which is made of metal materials such as steel plates.

[0081] Specifically, the brush spring 50, which is a constant force spring, is made of a long, strip-shaped metal plate. The spiral portion 51 of the brush spring 50 is formed by winding the long, strip-shaped metal plate into a spiral shape multiple times in only one direction. By pulling one end of the wire out from the spiral portion 51, the brush spring 50 can generate a force (spring restoring force) that makes the wire want to roll back into the original spiral portion 51.

[0082] like Figure 6 and Figure 7 As shown, the spiral portion 51, which is given a spring restoring force by pulling out the wire, contacts the rear end portion 42 of the brush 40, and can apply a pressing force (spring load) to the brush 40. That is, the brush spring 50 applies a pressing force to the brush 40 using the spiral portion 51, pressing the brush 40 against the commutator 30.

[0083] The brush spring 50 is configured with its scroll portion in a horizontal position relative to the rotating shaft 21. That is, the brush spring 50 is configured such that the central axis (scroll axis) of the scroll portion 51 is oriented along the axis C of the rotating shaft 21. Specifically, the perpendicular line of the scroll surface (coil surface) of the scroll portion 51 is substantially orthogonal to the axis C of the rotating shaft 21.

[0084] From an external power source located outside the motor 1 via Figure 4 and Figure 5 The power supply terminal 80 shown supplies power to the brush 40. The external power supply is a power source located outside the motor 1, supplying the motor 1 with a specified input voltage. In this embodiment, the external power supply is a DC power source that supplies the motor 1 with a DC 12V input voltage.

[0085] like Figure 4 and Figure 6As shown, the brush 40 is disposed within the brush holder 60. The brush holder 60 is a retaining member that holds the brush 40. The brush holder 60 not only holds the brush 40, but also the brush spring 50, the cover plate 70, and the power terminal 80. Figures 1-3 As shown, the brush holder 60 is also a housing component constituting the housing of the motor 1. The brush holder 60 covers the second bracket 102 from the outside.

[0086] The brush holder 60 is made of an insulating resin material. In this embodiment, the brush holder 60 is a resin molded article integrally formed from an insulating resin material. As an example, the resin material constituting the brush holder 60 is phenolic resin. However, it is not limited to this.

[0087] like Figure 3 and Figure 6 As shown, the brush holder 60 has a brush housing 61 for housing the brushes 40. The brush housing 61 is a brush housing that encloses the brushes 40. The number of brush housings 61 varies depending on the number of brushes 40. Figure 6 As shown, two brush housing portions 61 are formed in the brush holder 60. The two brush housing portions 61 are arranged in a figure-eight position when viewed from the axis C of the rotating shaft 21. Specifically, the two brush housing portions 61 are arranged at a 60° interval along the rotation direction of the rotor 20.

[0088] Each brush receiving section 61 is elongated in a direction orthogonal to the axis C of the rotating shaft 21 (i.e., radially), and its cross-sectional shape is a rectangular concave shape. Specifically, as shown... Figure 5 As shown, the brush holder 61 has a bottom 61a and a pair of sidewalls 61b vertically disposed on the bottom 61a. That is, the bottom 61a and the pair of sidewalls 61b form a concave section. The bottom 61a of the brush holder 61 supports the bottom surface of the brush 40. The pair of sidewalls 61b of the brush holder 61 hold the brush 40. The pair of sidewalls 61b are respectively opposite to a pair of side surfaces of the brush 40. The pair of sidewalls 61b may also contact the side surfaces of the brush 40, but it is preferable that there is a gap between the pair of sidewalls 61b and the side surfaces of the brush 40 so that the brush 40 can easily slide in the brush holder 61.

[0089] like Figure 3 As shown, the brush spring 50 is also housed together with the brush 40 in the brush housing 61. Therefore, the length of the brush housing 61 in the longitudinal direction is longer than the length of the brush 40. Specifically, the spiral portion 51 of the brush spring 50 is disposed behind the rear end portion 42 of the brush 40. In other words, the spiral portion 51 is disposed in the brush housing 61 in a manner opposite to the side where the commutator 30 is located, relative to the brush 40. Figure 7As shown, the brush spring 50 is fixed to the brush holder 60 by partially supporting the wire 52 pulled out from the spiral section 51. Specifically, the wire 52 pulled out from the spiral section 51 extends past the side of the brush 40 toward the commutator 30 and is fixed to the recess 61c formed in front of the brush receiving section 61. More specifically, the wire 52 is fixed to the brush holder 60 by engaging the bend formed at the tip of the wire 52 with the recess 61c of the brush holder 60.

[0090] The brush 40, housed in the brush housing 61, slides within the brush housing 61. Specifically, the front end 41 of the brush 40 gradually wears down due to friction with the commutator segment 31. As a result, the brush 40, pressed by the brush spring 50, moves towards the commutator 30 within the brush housing 61 using the pressing force based on the elasticity of the brush spring 50. That is, as the brush 40 gradually wears down, the rear end 42 of the brush 40 gradually moves in a direction (radial) toward the axis C of the rotating shaft 21. Consequently, the spiral portion 51 of the brush spring 50, which contacts the rear end 42 of the brush 40, also gradually moves together with the rear end 42 of the brush 40 toward the axis C of the rotating shaft 21.

[0091] like Figure 3 and Figure 4 As shown, a cover plate 70 is provided to cover the brush 40 housed in the brush housing 61. The cover plate 70 is configured to cover the brush housing 61. The cover plate 70 covers not only the brush 40 but also the brush spring 50. The cover plate 70 may or may not contact the upper surface of the brush 40. The cover plate 70 may or may not contact the pull-out wire 52 of the brush spring 50. There is a gap between the cover plate 70 and the spiral portion 51 of the brush spring 50.

[0092] Figure 8 This is a three-dimensional view of the cover plate when viewed from above at angle 70. Figure 9 This is a perspective view of the cover plate 70 from below. The cover plate 70 is a sheet metal made of a metal material such as brass or stainless steel (SUS). In this embodiment, the cover plate 70 is made of a sheet metal. For example, by performing sheet metal processing such as bending or stamping on a sheet metal plate that has been cut to a specified shape, a suitable cover plate can be obtained. Figure 8 and Figure 9 The cover plate 70 is shown in the diagram. (Example) Figure 8 and Figure 9 As shown, the cover plate 70 has a cover portion 71, a wall portion 72, and a leg portion 73.

[0093] The cover 71 is the main body (cover body) of the cover plate 70, covering the brush 40. The cover 71 covers not only the brush 40 but also the brush spring 50. The cover 71 is formed into an elongated strip along the length of the brush 40. The cover 71 is configured to cover the brush storage part 61 of the brush holder 60.

[0094] The cover portion 71 is bent in a manner that creates a step in the width direction of the cover portion 71. The cover portion 71 has a first plate portion 71a as the upper part of the step and a second plate portion 71b as the lower part of the step. Figure 7 As shown, the first plate portion 71a covers the upper surface of the brush 40. The portion lower than the first plate portion 71a, namely the second plate portion 71b, is located on the side 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 a limitation.

[0095] like Figure 7 As shown, the second plate portion 71b of the cover portion 71 covers the pull-out wire 52 of the brush spring 50. The second plate portion 71b also covers a portion of the scroll portion 51. The second plate portion 71b is close to both the portion of the scroll portion 51 and the pull-out wire 52 of the brush spring 50. Therefore, when the brush spring 50 is to tilt, the brush spring 50 abuts against the second plate portion 71b, thus suppressing the tilting of the brush spring 50. In addition, since the brush spring 50 abuts against the second plate portion 71b when the brush spring 50 is to tilt, the brush spring 50 does not abut against the first plate portion 71a. That is, the brush spring 50 does not contact the first plate portion 71a.

[0096] The wall portion 72 is formed to protrude from a side end 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 the end of the first plate portion 71a of the cover portion 71. In addition, the wall portion 72 extends along the length direction of the cover portion 71. The wall portion 72 is formed by partially bending the metal plate constituting the cover plate 70. The wall portion 72 and the cover portion 71 are formed with an L-shaped cross-section.

[0097] The leg 73 is formed to protrude from the side end of the cover 71 in the width direction. The leg 73 is erected on the cover 71 and extends in a direction orthogonal to the main surface of the cover 71. The leg 73 protrudes compared to the wall portion 72. The leg 73 is formed by partially bending the metal plate constituting the cover plate 70.

[0098] In this embodiment, three legs 73 are provided. One of the three legs 73 is located on one side of the cover 71 where the wall portion 72 is provided. Specifically, one leg 73 is located at the end of the first plate portion 71a of the cover 71. Two of the three legs 73 are located on the other side of the cover 71. Specifically, two legs 73 are located at the end of the second plate portion 71b of the cover 71. The three legs 73 are respectively inserted into three insertion holes 62 provided in the brush holder 60. Specifically, each leg 73 is pressed into a corresponding insertion hole 62. By pressing the legs 73 into the insertion holes 62, the cover 70 is fixed to the brush holder 60.

[0099] Figure 10 yes Figure 6 A cross-sectional view at line XX. For example... Figure 10 As shown, the brush 40 is surrounded by the brush housing 61 and the cover plate 70. That is, the brush housing 61 and the cover plate 70 constitute the brush box BX surrounding the brush 40. In other words, the brush box BX is composed of two parts: the resin brush housing 61 and the metal cover plate 70.

[0100] The brush box BX surrounds the four sides of the brush 40 and houses the brush 40. Specifically, the brush 40 is surrounded by the cover plate 70 and the bottom 61a and a pair of side wall portions 61b that constitute the brush housing portion 61.

[0101] The cover plate 70 covers not only the brush 40 but also the brush spring 50. Therefore, the brush housing BX covers not only the brush 40 but also the brush spring 50. That is, the brush spring 50 is housed in the brush housing BX and is surrounded by the cover plate 70 and the bottom 61a and a pair of sidewall portions 61b that constitute the brush housing portion 61.

[0102] The cover plate 70 covering the brush 40 is the top plate of the brush box BX. The wall portion 72 of the cover plate 70 is the first wall portion of the brush box BX. The bottom 61a of the brush storage portion 61 is the bottom of the brush box BX. The side wall portion 61b of the pair of side wall portions 61b of the brush storage portion 61 from which the brush feed braid 45 is led is the second wall portion of the brush box BX.

[0103] like Figure 10 As shown, the wall portion 72 (first wall portion) of the cover plate 70 protrudes towards the bottom of the brush box BX, i.e., the bottom 61a side of the brush storage portion 61. Specifically, the wall portion 72, which is the first wall portion, protrudes towards the side wall portion 61b, which is the second wall portion, one of a pair of side wall portions 61b. A gap G exists between the wall portion 72, which is the first wall portion, and the side wall portion 61b, which is the second wall portion, of the cover plate 70. The brush braid wire 45, which is connected to the brush 40, is led out from this gap G.

[0104] The wall portion 72, which is the first wall portion of the brush box BX, is positioned opposite the brush 40 with an open gap in the width direction of the brush 40. Specifically, the wall portion 72 (first wall portion) is opposite to the side of the brush feed braid 45 that is led out from one of the pair of side portions of the brush 40.

[0105] The side wall 61b, which is the second wall of the brush box BX, is also opposite to the side of the brush feed braid 45 that is led out from the pair of sides of the brush 40. The inner surface of the side wall 61b, which is the second wall, is close to the side of the brush 40.

[0106] In the cover plate 70, which serves as 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 pull-out wire 52 of the brush spring 50. The second plate portion 71b is located closer to the brush spring 50 side (i.e., the bottom 61a side of the brush storage portion 61) than the first plate portion 71a.

[0107] like Figure 2 As shown, the brush holder 60 has a recess 63 formed in a concave shape on its outer surface. The recess 63 is formed by providing an outwardly protruding wall portion 63a on the outer surface of the brush holder 60. The power terminal 80 is exposed in the recess 63. The power supply line 2 is connected to the power terminal 80. That is, the power supply line 2 is electrically connected and mechanically connected to the power terminal 80. An insulating member made of insulating resin material is filled in the recess 63.

[0108] Power terminal 80 receives power from an external power source via power supply line 2 as power to supply power to brush 40. Therefore, power terminal 80 is electrically connected to brush 40. The power supplied to brush 40 is then supplied to coil 22 of rotor 20. In this embodiment, the external power source is a DC power source, therefore power terminal 80 receives DC voltage as input voltage via power supply line 2. Therefore, two power terminals 80 are provided. One of the two power terminals 80 is a positive-side power supply terminal connected to the positive side of the DC power source. The other of the two power terminals 80 is a negative-side power supply terminal connected to the negative side of the DC power source. Both power terminals 80 are fixed to brush holder 60.

[0109] like Figure 4 As shown, the power terminal 80 and the brush 40 are electrically connected via a brush braid 45. The brush braid 45 is connected to one of a pair of sides of the brush 40. The brush braid 45 extends from the side of the brush 40. One end of the brush braid 45 is embedded in the side of the brush 40 and fixed to the brush 40. The other end of the brush braid 45 is connected to the power terminal 80. The brush braid 45 and the power terminal 80 are joined, for example, using solder. Power is supplied to the power terminal 80 from an external power source via the power supply line 2, thereby supplying current to the brush 40 via the brush braid 45 connected to the power terminal 80.

[0110] In the electric motor 1 configured as described above, when power is supplied to the power terminal 80 via the power supply line 2, the power is also supplied to the brushes 40 via the power terminal 80. As a result, armature current (drive current) flows to the coil 22 via the commutator 30, which is in contact with the brushes 40, generating magnetic flux in the rotor 20 (coil 22). The 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 the torque that rotates the rotor 20. At this time, the direction of the current flowing to the coil 22 is switched by utilizing the positional relationship between the commutator segments 31 and the brushes 40. By switching the direction of current flow in this way, a rotational force in a certain direction is generated by the repulsive and attractive forces of the magnetic forces generated between the stator 10 and the rotor 20, causing the rotor 20 to rotate around the axis C of the rotation shaft 21.

[0111] Figure 11 This is a diagram showing the positional relationship between the brush 40, brush spring 50, and cover plate 70 in the brush holder 60 of the electric motor 1 in Embodiment 1. Figure 11 The relationship between the brush 40, the brush spring 50, and the brush box BX (brush storage part 61, cover plate 70) is explained in detail.

[0112] like Figure 11 As shown, regarding brush 40, the height of brush 40 in the direction of its axis C is set as H. B Set the width of the brush 40 to W. B As mentioned above, the width of brush 40 is smaller than the height of brush 40. Therefore, W is satisfied. B <H B In this embodiment, the corners of the brush 40 are chamfered. Therefore, when the width of the upper and lower surfaces (excluding the chamfered portions) of the brush 40 is set to W... B1 When W is satisfied B1 <W B Without chamfering the corners of brush 40, W B1 =W B .

[0113] Regarding the height of the brush box BX (brush storage section 61), the height of the side wall portion 61b, which serves as the second wall portion, is defined as H1; the height of the brush spring holding space, which serves as the space required to hold the scroll portion 51 of the brush spring 50, is defined as H2; the height of the first brush holding space, which serves as the space required to hold the brush 40, is defined as H3; and the height of the second brush holding space, which serves as the space required to hold the brush 40, is defined as H4. In this case, the height H of the brush box BX (brush storage section 61) becomes H = H2 + H3 + H4. These heights related to the brush box BX are lengths in the direction of the axis C of the rotation shaft 21. In this embodiment, H2 is the height from the scroll surface below the scroll portion 51 of the brush spring 50 to the inner surface of the second plate portion 71b of the cover plate 70. H3 is the height from the inner surface of the bottom 61a of the brush storage section 61 to the scroll surface below the scroll portion 51 of the brush spring 50. H4 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.

[0114] Regarding the width of the brush box BX (brush storage section 61), the width of the brush holding space, which serves as the space for holding the brush 40, is defined as W1, and the width of the space for holding the brush spring 50 is defined as W2. In this embodiment, W1 is the interval between a pair of sidewall portions 61b of the brush storage section 61. W2 is the width of the sidewall portion 61b on the side opposite to the side from which the brush braid 45 is led out.

[0115] Regarding the brush spring 50, the height (spring width) of the spiral section 51 is set to W. S Let the outer diameter (diameter) of the vortex section 51 be D. S (See below) Figure 16B and Figure 17B ).

[0116] 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 set as K.

[0117] In this case, the following relationship is satisfied in the motor 1 of this embodiment.

[0118] H2>W S

[0119] H3 > H1

[0120] H4>0

[0121] · (D) S -W B ) / 2 < K < D S / 2

[0122] ·D S>W B

[0123] ·W2<D S / 2

[0124] Here, use Figure 12 and Figure 13 The features of the electric motor 1 of this embodiment will be described, including the process of implementing the technology disclosed herein. Figure 12 This is a diagram showing the relationship between the brush 40, the brush spring 50, and the brush box BX (brush storage part 61, cover plate 70X) in the comparative example motor 1X. Figure 13 This is a diagram used to illustrate the operation of the brush spring 50 in the electric motor 1X of the comparative example.

[0125] In brushed motors, when balancing high output and miniaturization, increased current leads to increased brush wear. Therefore, to suppress brush wear, increasing the brush cross-sectional area is considered. However, increasing the brush width (the dimension in the motor's rotation direction) and thus the brush cross-sectional area increases the contact area between the brush and the commutator segments, resulting in a decreased torque constant, reduced motor efficiency, increased heat generation, or increased sparking. Therefore, to balance high output and miniaturization, it is preferable to narrow the brush width while increasing the brush cross-sectional area. Specifically, as... Figure 12 As shown in the motor 1X, it is preferable to make the width W of the brush 40. B The height H is less than 40mm of the brush. B (W) B <H B ).

[0126] In high-speed brushed motors, to ensure stable contact between the commutator and the brushes, the spring load applied by the brush springs to the brushes needs to be at least a certain level. Furthermore, to maintain a constant spring load on the brushes from the initial stage to the later stage of brush wear, such as... Figure 12 As shown in the motor 1X, a constant force spring is considered as the brush spring 50. However, when a constant force spring is used as the brush spring 50, the cross-section of the brush spring 50 becomes larger compared to the case where a coil spring is used as the brush spring 50. Therefore, when the brush spring 50, as a constant force spring, deviates from its designated position, the brush spring 50 comes into contact with components inside the motor, resulting in a loss of spring load, or brush locking occurs due to the brush spring 50 falling off.

[0127] For example, when a constant force spring is used as the brush spring 50, such as Figure 13As shown, the spiral portion 51 of the brush spring 50, which contacts the rear end of the brush 40, follows different trajectories when the brush spring 50 is extended (during brush 40 assembly) and when the brush spring 50 is contracted (during brush 40 wear). As a result, as indicated by the block arrow, the spiral portion 51 of the brush spring 50 may detach towards the brush braid 45. If the motor 1 vibrates significantly during transport or installation, the brush spring 50 may spring up due to this vibration, and the spiral portion 51 may detach beyond the rear end face of the brush 40. In particular, when the width W of the brush 40 is made as described above... B The height H is less than 40mm of the brush. B Time (W) B <H B As the width of the brush 40 narrows, the spiral portion 51 of the brush spring 50 is prone to detachment.

[0128] At this time, the width W of the bottom surface of brush 40 B1 The height (spring width) W of the spiral portion 51 of the brush spring 50 S Become W B1 ≈W S or W B1 <W S The brush width is 40W. B The height H is less than 40mm of the brush. B (W) B <H B This makes it impossible to position the scroll portion 51 of the brush spring 50 longitudinally (along the axis C), as... Figure 12 and Figure 13 As shown, the spiral portion 51 of the brush spring 50 must be positioned horizontally (along the direction of rotation).

[0129] Therefore, the inventors of this application conducted in-depth research on the following strategy: even when seeking a balance between high output and miniaturization of the brushed motor, the width W of the brush 40 is reduced. B The height H of the brush is 40. B Small (W) B <H B Furthermore, when the scroll portion 51 of the brush spring 50, which serves as a constant force spring, is horizontally positioned, it is also possible to prevent the scroll portion 51 of the brush spring 50 from falling off.

[0130] As a result, the inventors of this application discovered that the problem could be solved by designing the structure of the brush box BX.

[0131] Specifically, in the motor 1 of this embodiment, a wall portion 72 (first wall portion) is provided on the cover plate 70 constituting the top plate portion of the brush box BX. The wall portion 72 protrudes toward the bottom side of the brush box BX and is openly opposed to the brush 40 in the width direction of the brush 40.

[0132] According to this structure, even when the width W of the brush 40 is... B The height H of the brush is 40. B Small (W) B <H B Furthermore, even when the scroll portion 51 of the brush spring 50, which functions as a constant force spring, is horizontally positioned, it is possible to prevent the scroll portion 51 of the brush spring 50 from detaching beyond the rear end face of the brush 40. That is, the wall portion 72 provided on the cover plate 70 (top plate portion) functions as an anti-detachment wall to prevent the scroll portion 51 of the brush spring 50 from detaching. Thus, the motor 1 according to this embodiment can suppress the brush spring 50, which functions as a constant force spring, from shifting from a predetermined position while simultaneously achieving high output and miniaturization.

[0133] 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 Preferably, K < D is satisfied. S The relationship is / 2.

[0134] By satisfying this relationship, 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 face of the brush 40. That is, the spiral portion 51 of the brush spring 50 can apply a spring load perpendicularly to the rear end face of the brush 40. Therefore, the vector of the brush spring 50 pressing the brush 40 can be made to be the travel direction of the brush 40. As a result, no unnecessary force that would cause the brush 40 to tilt is applied to the brush 40 by the spiral portion 51, thus stabilizing the sliding of the brush 40. It is further preferable to satisfy D. S >W B K > (D S -W B The relationship is ) / 2.

[0135] Furthermore, in the electric motor 1 of this embodiment, the heights H1, H2, H3, and H4 related to the height H of the brush box BX in the axial direction C of the rotating shaft 21, and the height W of the scroll section 51 are also considered. S As mentioned above, H2 > W S The relationship between H3 > H1 and H4 > 0.

[0136] By satisfying this relationship, 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 will not come into contact with the components inside the motor, thus reducing the loss of spring load.

[0137] Furthermore, in the electric motor 1 of this embodiment, as described above, W2 < D is satisfied. S The relationship is / 2.

[0138] On one of the pair of sidewall portions 61b of the brush receiving portion 61, the brush braid 45 is led out from the brush 40, so there is no wall supporting the brush 40. Therefore, by measuring the width W2 of the sidewall portion 61b opposite to the side where the brush braid 45 is led out and the outer diameter D of the spiral portion 51 of the brush spring 50, the brush braid 45 is drawn out from the brush receiving portion 61. S Let W2 < D S / 2, thus the center (coil center) of the spiral portion 51 of the brush spring 50 is within the width of the brush 40, making the direction of the spring load applied from the center of the spiral portion 51 of the brush spring 50 perpendicular to the rear end face of the brush 40. Therefore, it is less likely to apply excessive force from the spiral portion 51 to the brush 40, causing the brush 40 to tilt, thus making the sliding of the brush 40 more stable.

[0139] (Implementation Method 2)

[0140] Next, use Figure 14 The electric motor 1A of Embodiment 2 will be described. Figure 14 This is a partial enlarged top view of the electric motor 1A according to Embodiment 2.

[0141] In this embodiment, the shape of the rear end portion 42 of the brush 40A differs from that of the motor 1 in Embodiment 1 described above. Specifically, as follows... Figure 14 As shown, in the motor 1A of this embodiment, the rear end portion 42 of the brush 40A is provided with: a contact surface 42a, which partially contacts the spiral portion 51 of the brush spring 50; and a protrusion 43, which protrudes rearward beyond the contact surface 42a and provides another partial contact with the spiral portion 51. The protrusion 43 is provided near the side of one of the pair of sides of the brush 40A where the brush braid 45 is connected. Specifically, the protrusion 43 is provided at the end of the side of one of the pair of sides of the brush 40A where the brush braid 45 is connected (the end in the width direction of the brush 40A).

[0142] In the electric motor 1A of this embodiment, the cover plate 70 constituting the top plate of the brush box BX also has a wall portion 72 opposite to the brush 40A with an opening gap K.

[0143] According to this structure, even when the width W of the brush is 40A... B The height H of the brush 40A B Even when the volute portion 51 of the brush spring 50, which functions as a constant force spring, is horizontally positioned, it is possible to prevent the volute portion 51 of the brush spring 50 from detaching beyond the rear end face of the brush 40A. Therefore, it is possible to suppress the brush spring 50, which functions as a constant force spring, from shifting from a predetermined position while achieving both high output and miniaturization.

[0144] At this time, if the gap K between the wall 72 (anti-fall-off wall) and the brush 40A is narrow, the following possibilities exist: the brush spring 50 contacts the wall 72 of the cover plate 70, resulting in a loss of spring load, or the brush spring 50 is fixed to the cover plate 70 due to micro-sliding wear.

[0145] In contrast, in the motor 1A of this embodiment, since a protrusion 43 is provided at the rear end 42 of the brush 40A, it is possible to suppress the spiral portion 51 of the brush spring 50 from shifting toward the wall portion 72 of the cover plate 70. Therefore, it is possible to prevent the spiral portion 51 of the brush spring 50 from contacting the wall portion 72 of the cover plate 70.

[0146] The protrusion 43 provided at the rear end 42 of the brush 40A serves to prevent the spiral portion 51 of the brush spring 50 from falling off beyond the rear end face of the brush 40. In other words, the protrusion 43 of the brush 40A, like the wall portion 72 of the cover plate 70, functions as an anti-fall-off wall to prevent the spiral portion 51 of the brush spring 50 from falling off. Therefore, in the electric motor 1A, a dual safety mechanism consisting of the protrusion 43 of the brush 40A and the wall portion 72 of the cover plate 70 can be realized.

[0147] Since the protrusion 43 of the brush 40A functions as an anti-detachment wall, the cover plate 70 may not have a wall portion 72 in the motor 1A of this embodiment. That is, in this embodiment, the cover plate 70 may be changed to... Figure 12 The cover plate shown is 70X.

[0148] Furthermore, in the electric motor 1A of this embodiment, the side surface inside the protrusion 43 (the side of the volute portion 51) provided at the rear end 42 of the brush 40A is a curved surface. However, it is not limited to this. Figure 15 This is a partial enlarged top view of the electric motor 1B, a modified example of Embodiment 2. For example, as shown... Figure 15 As shown in the motor 1B, the side surface inside the protrusion 43B (the side of the vortex portion 51) provided at the rear end 42 of the brush 40B can also be a planar inclined surface.

[0149] According to this structure, even if the spiral portion 51 of the brush spring 50 bounces up due to vibration or the like, it will return to its original position using the inclined surface of the protrusion 43B. This further suppresses the brush spring 50 from shifting from its intended position.

[0150] (Variation Example 1)

[0151] Next, use Figure 16A and Figure 16B The motor 1C of Modified Example 1 will be described. Figure 16A This is a diagram showing the structure of the brush box BX of the electric motor 1C in Modified Example 1. Figure 16BThis is a diagram showing the brush 40C and brush spring 50 of the electric motor 1C in Modified Example 1.

[0152] In this modified example, the shape of the cover plate 70C of the brush box BX and the shape of the brush 40C are different from those of the motor 1 in Embodiment 1 described above.

[0153] Specifically, such as Figure 16A and Figure 16B As shown, in the electric motor 1C of this modified example, a groove 44 is formed at the rear end 42 of the brush 40C to insert the spiral portion 51 of the brush spring 50. This suppresses tilting of the spiral portion 51 of the brush spring 50. In the above-described embodiment 1, 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. According to the second plate portion 71b of the cover portion 71, even if the spiral portion 51 tilts, it will not contact the components inside the electric motor 1C, reducing the loss of spring load. In this modified example, the tilting of the spiral portion 51 is suppressed by using the brush 40C. Therefore, it is also possible that the cover portion 71 of the cover plate 70 is not provided with a step. Therefore, in this modified example, a cover plate 70C having a cover portion 71C without a step and a wall portion 72 is used.

[0154] In the motor 1C configured in this way, the brush box BX, consisting of a cover plate 70C and a brush housing 61, has: a bottom, which is the bottom 61a of the brush housing 61; and a side wall portion 61b (the side wall portion 61b from which the brush braid 45 is led out of the pair of side wall portions 61b), which is erected at the bottom and faces the side of the brush 40C. The brush braid 45, which is connected to the brush 40C, is led out from the gap G between the wall portion 72 (first wall portion) of the cover plate 70C and the side wall portion 61b (second wall portion). Figure 16A As shown, when the height of the side wall portion 61b, which is the second wall portion, is set to H1, the height from the scroll surface of the scroll portion 51 of the brush spring 50 below to the inner surface of the cover plate 70, which is the top plate portion, is set to H2, the height from the inner surface of the bottom 61a of the brush storage portion 61, which is the bottom of the brush box BX, to the scroll surface of the scroll portion 51 below, and the height of the scroll portion 51 is set to W... S Let H be the height from the groove 44 of brush 40C to the upper surface of brush 40. B1 Let H be the height from the lower surface of brush 40 to the groove 44 of brush 40C. B2 When H2 > W S H3 > H B2 >H1, H B1 A relational expression greater than 0.

[0155] In the above-described modified electric motor 1C, the cover plate 70C constituting the top plate of the brush box BX also has a wall portion 72 opposite to the brush 40C with an opening gap K.

[0156] According to this structure, even when the width W of the brush is 40C, B The height H of the brush 40C B Even when the volute portion 51 of the brush spring 50, which functions as a constant force spring, is horizontally positioned, it is possible to prevent the volute portion 51 of the brush spring 50 from detaching beyond the rear end face of the brush 40C. Therefore, in this modified example, it is possible to suppress the brush spring 50, which functions as a constant force spring, from shifting from a predetermined position while simultaneously achieving high output and miniaturization.

[0157] (Variation Example 2)

[0158] Next, use Figure 17A and Figure 17B The motor 1D of Modified Example 2 will be described. Figure 17A This is a diagram showing the structure of the brush box BX of the electric motor 1D in Modified Example 2. Figure 17B This is a diagram showing the brush 40D and brush spring 50 of the motor 1D in Modified Example 2.

[0159] In this modified example, the shape of the brush box BX and the shape of the brush 40D are different from those of the motor 1 in Embodiment 1 described above.

[0160] Specifically, the brush box BX in Embodiment 1 described above consists of two parts: a brush storage section 61 and a cover plate 70. On the other hand, as... Figure 17A As shown, the brush box BX of this modified example is composed only of the brush housing portion 61D. In addition to a bottom 61a and a pair of sidewall portions 61b, the brush housing portion 61D of this modified example also has an upper portion 61d that serves as the top plate portion of the brush box BX. The upper portion 61d (top plate portion) has: a first plate portion 61d1 that covers the upper surface of the brush 40D; a second plate portion 61d2 that is located closer to the spiral portion 51 than the first plate portion 61d1 and covers the spiral surface of the upper side of the spiral portion 51; and a third plate portion 61d3 that covers the upper surface portion of the side surface of the brush 40D. The upper portion 61d, as the top plate portion, has a wall portion 61d4 that protrudes toward the bottom 61a. The wall portion 61d4, like the wall portion 72 of the cover plate 70 in the above embodiment, is a first wall portion opposite to the brush 40D with a gap K in the width direction of the brush 40D. The brush braid 45 connected to the brush 40D is led out from the gap G between the wall portion 61d4, which is the first wall portion, and the side wall portion 61b, which is the second wall portion (the side wall portion 61b on the side from which the brush braid 45 is led out of the pair of side wall portions 61b).

[0161] Thus, in the electric motor 1D of this modified example, the upper part 61d of the brush receiving part 61 constituting the top plate of the brush box BX also has a wall part 61d4 opposite to the brush 40D with an opening gap K.

[0162] According to this structure, even when the width W of the brush is 40D... B The height H of the brush 40D B Even when the volute portion 51 of the brush spring 50, which functions as a constant force spring, is horizontally positioned, it is possible to prevent the volute portion 51 of the brush spring 50 from detaching beyond the rear end face of the brush 40D. Therefore, in this modified example, it is possible to suppress the brush spring 50, which functions as a constant force spring, from shifting from a predetermined position while simultaneously achieving high output and miniaturization.

[0163] like Figure 17B As shown, in the electric motor 1D, a protrusion 43D is provided at the rear end 42 of the brush 40D, protruding rearward and contacting the spiral portion 51. The protrusion 43D is located near the side of one of the pair of sides of the brush 40 where the brush braid 45 is connected. The side of the protrusion 43D near the spiral portion 51 is a planar inclined surface. The protrusion 43D is provided throughout the entire rear end 42 of the brush 40D. The inclined surface of the protrusion 43D is the rear end face of the brush 40D. Therefore, the spiral portion 51 of the brush spring 50 only contacts the rear end face of the brush 40D, i.e., the inclined surface of the protrusion 43D. Thus, the spiral portion 51 of the brush spring 50 can apply a spring load to the rear end face of the brush 40 in an oblique direction opposite to the direction of the brush braid 45. That is, the vector of the brush spring 50 pressing the brush 40 is oblique in the direction opposite to the direction of the brush braid 45. Therefore, in the electric motor 1D of this modified example, it is possible to further suppress the vortex section 51 from falling off towards the braided wire 45 side.

[0164] Thus, the motor 1D of this modified example has a structure in which the upper and lower surfaces of the brush 40D are supported by a brush box BX formed integrally by using a sliding mold. Specifically, as Figure 17A As shown, when the height of the side wall portion 61b, which serves as the second wall portion, is set to H1, 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 set to H2, the height from the inner surface of the bottom 61a of the brush box BX to the lower spiral surface of the spiral portion 51 is set to H3, the height from the inner surface of the second plate portion 61d2 of the upper portion 61d to the inner surface of the first plate portion 61d1 is set to H4, the height from the inner surface of the third plate portion 61d3 of the upper portion 61d to the inner surface of the first plate portion 61d1 is set to H5, and the height of the spiral portion 51 is set to W... S When H2 > W S The relationships H3 > H1 and H4 > H5.

[0165] (Other variations)

[0166] The electric motor of this disclosure has been described above based on the embodiments and modifications. However, this disclosure is not limited to the above embodiments and modifications.

[0167] For example, in the above embodiment, the two brushes 40 are arranged in a figure-eight configuration when viewed from above, but this is not a limitation. As an example, the two brushes 40 may also be arranged opposite each other in a straight line, separated by the commutator 30. That is, the two brushes 40 may also be arranged at 180° intervals along the rotation direction of the rotor 20. Furthermore, the number of brushes 40 is not limited to two.

[0168] Furthermore, in the above embodiment, the rotating shaft 21 is supported by two bearings, the first bearing 91 and the second bearing 92. However, it is not limited to this. Specifically, the rotating shaft 21 may also be supported by a single bearing.

[0169] Furthermore, in the above embodiment, the motor 1 is a coreless motor in which the stator 10 and rotor 20 do not have cores. However, it is not limited to this. For example, the motor 1 may also be a motor in which the stator 10 and rotor 20 have cores. However, by making it a coreless motor as described in the above embodiment, it is possible to achieve a motor 1 with lower inductance and a thinner profile.

[0170] Furthermore, in the above embodiment, the stator 10 is composed only of permanent magnets. However, it is not limited to this. For example, the stator 10 may also be a stator composed of permanent magnets and an iron core, or it may be an armature composed of stator windings and an iron core without using permanent magnets.

[0171] Furthermore, in the above embodiment, the motor 1 is a flat motor with a thickness smaller than its outer diameter. However, it is not limited to this. The technology disclosed herein can also be applied, for example, to cylindrical motors with a cylindrical housing having a thickness larger than its outer diameter.

[0172] 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 a limitation. Specifically, the direction of the main magnetic flux generated by the stator 10 and the rotor 20 can also be a direction orthogonal to the direction in which the axis C of the rotating shaft 21 extends (the radial direction of the rotation of the rotating shaft 21). For example, the technology disclosed herein can also be applied to an inner rotor type motor in which the rotor 20 is disposed inside the stator 10.

[0173] Furthermore, in the above embodiment, the electric motor 1 is a vehicle motor used in a vehicle. However, it is not limited to this. The technology disclosed herein can also be applied, for example, to electric motors used in electric blowers such as electric vacuum cleaners, and electric motors used in various other electrical devices.

[0174] In addition, this disclosure also includes various modifications conceived by those skilled in the art to the above embodiments, or methods implemented by arbitrarily combining the constituent elements and functions of the embodiments without departing from the spirit of this disclosure. Solutions obtained by arbitrarily combining two or more claims from the multiple claims recited in the claims at the time of filing this application, to the extent that they are not technically contradictory, are also included in this disclosure. For example, when a dependent claim recited in the claims at the time of filing this application is designated as a plurality of dependent claims or a plurality of dependent claims by referencing all superior claims to the extent that they are not technically contradictory, the combination of all claims included in such plurality of dependent claims or a plurality of dependent claims is also included in this disclosure.

[0175] Industrial availability

[0176] The technology disclosed herein can be widely used in electric motors and various products equipped with electric motors, exemplified by products in the fields of automotive and other electrical equipment and household electrical equipment.

[0177] Explanation of reference numerals in the attached figures

[0178] 1. 1A, 1B, 1C, 1D, 1X, 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, Protrusion; 44. Groove; 45. Brush braid; 50. Brush spring; 51. Spiral section; 52. Lead-out wire; 60. Brush holder; 61. 6 1D, Brush housing; 61a, Bottom; 61b, Side wall; 61c, Recess; 61d, Upper part; 61d1, First plate; 61d2, Second plate; 61d3, Third plate; 61d4, Wall; 62, Insertion hole; 63, Recess; 63a, Wall; 70, 70C, 70X, Cover plate; 71, 71C, Cover; 71a, First plate; 71b, Second plate; 72, Wall; 73, Leg; 80, Power terminal; 91, First bearing; 92, Second bearing; 101, First bracket; 102, Second bracket; BX, Brush box.

Claims

1. An electric motor, wherein, This electric motor has the following features: A rotor having a rotating shaft extending along an axial direction, the axial direction being the direction in which the rotating shaft extends axially; A commutator, which is mounted on the rotating shaft; The brush is in contact with the commutator; A brush spring that presses the brush against the commutator; as well as Brush housing, which surrounds the brush, The brush spring is a constant force spring having a spiral portion formed by winding a strip of wire. The brush has height in the axial direction and width in the circumferential direction of the rotor. It is spring-loaded by the constant-force spring in a manner that propels it toward the commutator side, and includes a front end that contacts the commutator and a rear end that contacts the scroll portion. The constant force spring is configured relative to the rotating shaft such that the central axis of the scroll portion is aligned with the axis of the rotating shaft. When the height of the brush is set to H B The width of the brush is set to W. B When W is satisfied B <H B , The brush box has a top plate that covers the brush. The top plate has a first wall portion that protrudes toward the bottom side of the brush box. The first wall portion is openly positioned opposite the brush in the direction of the width of the brush.

2. The electric motor according to claim 1, wherein, When the gap is set to K, and the outer diameter of the vortex section is set to D... S When K < D S / 2.

3. The electric motor according to claim 2, wherein, Satisfy D S >W B K > (D S -W B ) / 2.

4. The electric motor according to claim 1, wherein, 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 portion of the brush spring. The brush box has a second wall portion that is vertically disposed at the bottom and opposite to the side of the brush. The brush braid wire connected to the brush extends from between the first wall portion and the second wall portion. When the height of the second wall portion is set to H1, the height from the lower scroll surface of the scroll portion to the inner surface of the second plate portion is set to H2, the height from the inner surface of the bottom of the brush box to the lower scroll surface of the scroll portion is set to H3, the height from the inner surface of the second plate portion to the inner surface of the first plate portion is set to H4, and the height of the scroll portion in the axial direction is set to W... S When H2 > W S H3 > H1, H4 > 0.

5. The electric motor according to claim 1, wherein, A groove is formed at the rear end of the brush for the spiral portion to be inserted. The brush box has a bottom and a second wall portion that is vertically disposed on the bottom and opposite to the side of the brush. The brush braid wire connected to the brush extends from between the first wall portion and the second wall portion. When the height of the second wall portion is set to H1, the height from the lower scroll surface of the scroll portion to the inner surface of the top plate portion is set to H2, the height from the inner surface of the bottom of the brush box to the lower scroll surface of the scroll portion is set to H3, and the height of the scroll portion is set to W... S The height from the groove to the upper surface of the brush is set as H. B1 The height from the lower surface of the brush to the groove is set as H. B2 When H2 > W S H3 > H B2 >H1, H B1 >0.

6. The electric motor according to any one of claims 1 to 5, wherein, The motor also includes a brush holder with a brush storage section for receiving the brushes. The brush box has a brush storage section and a cover plate covering the brush. The top plate portion is the cover plate.

7. The electric motor according to claim 1, wherein, The rear end of the brush has a protrusion that extends rearward and contacts the volute portion. The protrusion is located on one of the pair of sides of the brush that is connected to the brush braid. The side of the protrusion closest to the volute is an inclined surface. 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 volute portion than the first plate portion and covers the upper volute surface of the volute portion. And the third plate portion, which covers the upper surface portion of the side of the brush. The brush box has a second wall portion that is vertically disposed at the bottom and opposite to the side of the brush. The brush braid wire connected to the brush extends from between the first wall portion and the second wall portion. When the height of the second wall portion is set to H1, the height from the lower spiral surface of the spiral portion to the inner surface of the second plate portion is set to H2, the height from the inner surface of the bottom of the brush box to the lower spiral surface of the spiral portion is set to H3, the height from the inner surface of the second plate portion to the inner surface of the first plate portion is set to H4, the height from the inner surface of the third plate portion to the inner surface of the first plate portion is set to H5, and the height of the spiral portion is set to W... S When H2 > W S H3 > H1, H4 > H5.

8. The electric motor according to claim 1, wherein, The rear end of the brush is provided with: a contact surface for partial contact of the spiral portion; and a protrusion that protrudes rearward beyond the contact surface and for another partial contact of the spiral portion. The protrusion is located on one of the two sides of the brush that is connected to the brush braid.

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

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

11. An electric motor, wherein, This electric motor has the following features: A rotor having a rotating shaft extending along an axial direction, the axial direction being the direction in which the rotating shaft extends axially; A commutator, which is mounted on the rotating shaft; The brush is in contact with the commutator; A brush spring that presses the brush against the commutator; as well as Brush housing, which surrounds the brush, The brush spring is a constant force spring having a spiral portion formed by winding a strip of wire. The brush is subjected to a spring force by the constant force spring in a manner that propels it toward the commutator side, and includes a front end that contacts the commutator and a rear end that contacts the scroll portion. The constant force spring is configured relative to the rotating shaft such that the central axis of the scroll portion is aligned with the axis of the rotating shaft. The rear end of the brush is provided with: a contact surface for partial contact of the spiral portion; and a protrusion that protrudes rearward beyond the contact surface and for another partial contact of the spiral portion. The protrusion is located on one of the two sides of the brush that is connected to the brush braid.

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

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