Electric motor

Abstract

The motor includes: a rotor having a rotating shaft extending in an axial direction; 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 holder that holds the brush spring. The brush spring is a constant load spring having a wrap formed by winding a belt-shaped wire material, and the constant load spring applies a pressing force to the brush by means of the wrap in contact with the rear end surface of the brush. The holder has a first support portion that supports the wrap portion when the wrap portion moves toward the rotating shaft due to wear of the brush, and the spring load generated by the brush spring becomes zero when the wrap portion comes into contact with the first support portion.

Description

Technical Field

[0001] This disclosure relates to an electric motor. Background Technology

[0002] Electric motors are also widely used in fields such as electrical systems installed in automobiles and other vehicles. For example, two-wheeled or four-wheeled vehicles use electric motors to drive cooling fans that cool radiators and 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 includes: a stator; a rotor that rotates under the magnetic force of the stator; a commutator that is mounted on the rotating shaft of the rotor; and brushes that are in contact with the commutator.

[0004] Brush springs are used in brushed motors to press the brushes against the commutator. The brush springs utilize their elasticity to apply pressure to the brushes. Traditionally, coil springs or torsion springs were used as brush springs in brushed motors.

[0005] However, when using helical springs or torsion springs as brush springs, such as Figure 20 As shown by the dashed line, the spring load applied to the brush by the brush spring is not constant, but gradually decreases as the brush wears. Figure 20 This diagram schematically illustrates the variation of the brush spring load relative to brush wear when using helical springs, torsion springs, and constant-load springs as brush springs. Therefore, the difference between the initial pressure (starting pressure) before brush wear and the final pressure (ending pressure) when the motor reaches the end of its lifespan due to brush wear becomes larger. Therefore, when using helical or torsion springs, it is advisable to set the initial pressure higher to ensure a final pressure above constant. However, this results in increased friction between the brushes and the commutator during the initial stage of rotor rotation, leading to increased 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, higher pressure increases mechanical wear, while lower pressure causes the brushes to spring back, generating sparks and increasing electrical wear.

[0007] Therefore, conventionally, techniques have been proposed to use a constant-load spring as the brush spring, where the spring load remains constant relative to the brush wear (stroke). By using a constant-load 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 a strip of wire wound in a spiral shape as a constant-load spring, and 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] A constant-load spring can apply a constant spring load to the brush, thus effectively suppressing brush wear. However, as... Figure 20 As the solid line shows, even a constant-load spring is not actually a constant load; there are periods when a constant spring load cannot be applied to the brush. In other words, even with a constant-load spring, there are periods where the spring load changes as the brush wears. Specifically, as... Figure 20 As shown, in the initial stage when the brush begins to wear and in the final stage when the brush is nearing the end of its lifespan, the spring load generated by the constant load spring is not constant, but gradually decreases as the brush wears.

[0009] Therefore, even when using constant load springs as brush springs, brush wear becomes unstable, and the quality of the motor sometimes deteriorates.

[0010] In particular, towards the end of the brush's lifespan, if the spring load is not constant, not only will electrical wear caused by sparking accelerate, but the pressing force applied to the brush by the constant load spring will also be insufficient or unstable. Consequently, the contact resistance between the brush and the constant load spring increases unevenly, leading to a deterioration in the motor's characteristics or unstable operation. Therefore, the quality of the motor deteriorates.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 61-118987 Summary of the Invention

[0014] This disclosure was made to solve such a problem. The purpose of this disclosure is to provide an electric motor that can improve the quality of the motor at the end of the brush life.

[0015] 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; a commutator mounted on the rotating shaft; a brush in contact with the commutator; a brush spring for pressing the brush against the commutator; and a retainer for retaining the brush spring, the brush spring being a constant load spring having a spiral portion formed by winding a strip of wire, the constant load spring applying a pressing force to the brush by means of the spiral portion in contact with the rear end face of the brush, the retainer having a first support portion that supports the spiral portion when the spiral portion moves toward the rotating shaft due to brush wear, and when the spiral portion abuts against the first support portion, the spring load generated by the brush spring becomes zero.

[0016] According to this disclosure, the quality of electric motors at the end of their brush life can be improved. Attached Figure Description

[0017] Figure 1 This is a perspective view of the electric motor as seen from above in the embodiment.

[0018] Figure 2 This is a perspective view of the electric motor as seen from below in the embodiment.

[0019] Figure 3 This is a cross-sectional view of the electric motor according to the embodiment.

[0020] Figure 4 This is a perspective view showing the brush holder in the electric motor and various components disposed on the brush holder according to the embodiment.

[0021] Figure 5 The electric motor in the implementation method Figure 4 The exploded perspective view of the brush holder and various components is shown.

[0022] Figure 6 This is a top view showing the arrangement of the electric motor, brushes, and brush springs in the brush holder according to the embodiment.

[0023] Figure 7 This is a top view showing the situation where the spiral portion of the brush spring in the electric motor of the embodiment moves due to brush wear.

[0024] Figure 8A This is a perspective view showing the structure of the brush spring assembled before the brush holder in the electric motor of the embodiment.

[0025] Figure 8B This is a side view showing the structure of the brush spring assembled before the brush holder in the electric motor of the embodiment.

[0026] Figure 9This diagram illustrates the configuration of an electric motor in which the brush spring is assembled onto the brush holder.

[0027] Figure 10 This is a diagram schematically illustrating the change in the spring load of the brush spring in an electric motor according to an embodiment, relative to the amount of brush wear.

[0028] Figure 11 This is a top view showing the structure of the brush holder of the electric motor in Modified Example 1.

[0029] Figure 12 This is a top view showing the structure of the brush holder of the electric motor in Modified Example 2.

[0030] Figure 13 This is a top view showing the structure of the brush holder of the electric motor in Modified Example 3.

[0031] Figure 14 This is a diagram showing the first variation of a brush spring as a constant load spring.

[0032] Figure 15 This is a diagram showing the second variation of a brush spring as a constant load spring.

[0033] Figure 16 It means to use Figure 14 and Figure 15 The top view of the structure of the brush holder of the motor in the modified example 4 of the brush spring shown.

[0034] Figure 17 This is a top view showing the structure of the brush holder of the electric motor in Modified Example 5.

[0035] Figure 18A This is a diagram showing the structure of another brush spring assembled before the brush holder in the electric motor of Modified Example 6.

[0036] Figure 18B This is a side view showing the structure of another brush spring assembled before the brush holder in the electric motor of Modified Example 6.

[0037] Figure 19 This refers to the motor in variation example 6. Figure 18A , Figure 18B The diagram shows another brush spring assembled with the brush holder.

[0038] Figure 20 This is a schematic diagram illustrating the variation of the spring load of a brush spring relative to the amount of brush wear when using helical springs, torsion springs, and constant load springs as brush springs. Detailed Implementation

[0039] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below represent 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, any 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.

[0040] Each figure is a schematic diagram and not necessarily a rigorous illustration. Furthermore, in each figure, structures substantially identical to those in other figures are labeled with the same reference numerals, and repetitive descriptions are omitted or simplified.

[0041] 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 direction extending from the axis C of the rotation shaft 21 (also simply referred to as the "axial direction"). In this specification, the terms "up" and "down" do not necessarily refer to the absolute spatial perception of the upward (vertical) and downward (vertical) directions.

[0042] (Implementation Method)

[0043] use Figures 1 to 7 The overall structure of the electric motor 1 in the embodiment will be described. Figure 1 This is a perspective view of the electric motor 1 as seen from above in the embodiment. Figure 2 This is a perspective view of the electric motor 1 as seen from below in the embodiment. Figure 3 This is a cross-sectional view of the electric motor 1 according to the embodiment. Figure 4 This is a perspective view showing the brush holder 60 in the electric motor 1 according to the embodiment and various components disposed on the brush holder 60. Figure 5 The electric motor 1 in the implementation method Figure 4 The exploded perspective view of the brush holder 60 and various components is shown. Figure 6 This is a top view showing the brush 40 and brush spring 50 disposed in the brush holder 60 in the electric motor 1 of the embodiment. Figure 7 This diagram illustrates the situation where the spiral portion 51 of the brush spring 50 in the electric motor 1 of the embodiment moves due to wear of the brush 40. Figure 7 In the original text, brush 40 was omitted.

[0044] like Figure 3As shown, the electric motor 1 includes a stator 10 and a rotor 20 that rotates under the magnetic force of the stator 10. The electric motor 1 is a brushed electric motor. The electric motor 1 also includes: a commutator 30 mounted on 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 covering the brush 40. Figure 3 , Figure 4 and Figure 5 As shown, the motor 1 also includes a power terminal 80 electrically connected to the brush 40, a first bearing 91, a second bearing 92, a first bracket 101, and a second bracket 102.

[0045] Electric motor 1 is a type of DC motor (DC motor) driven by direct current. In electric motor 1, a magnet is used as the stator 10. An armature with coils 22 is used as the rotor 20. Electric motor 1 is a flat-type (flat-plate) brushed coreless motor (flat-plate motor) mounted in two-wheeled or four-wheeled vehicles. Therefore, the stator 10 and rotor 20 do not have a core, resulting in a thin and lightweight overall structure for electric motor 1. Specifically, electric motor 1 is a small motor used for cooling fans in radiators of vehicles. The outer diameter (φ) of electric motor 1 is 120 mm or less. For example, the outer diameter φ of electric motor 1 is φ60 mm, φ70 mm, or φ90 mm, etc. Electric motor 1 is driven by power supplied from an external power source such as a battery. For example, electric motor 1 is driven by a DC 12V input voltage supplied via a power supply line connected to an external power source.

[0046] The following is a detailed description of each component of the electric motor 1.

[0047] like Figure 3 As shown, the stator 10 is disposed 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 a structure that generates magnetic flux on the air gap surface opposite the rotor 20, separated by the air gap. The stator 10, together with the armature stator 10, forms a magnetic circuit. Specifically, the stator 10 is generally annular. The stator 10 is configured such that N poles and S poles are alternately and equally present on the air gap surface opposite the rotor 20, separated by the air gap, along the circumference of the rotation axis 21. The stator 10 is the magnetic field that generates magnetic flux for generating torque. The stator 10 is composed of multiple magnets 11. The magnets 11 constituting the stator 10 are, for example, permanent magnets.

[0048] The stator 10 comprises multiple magnets 11 arranged such that N and S poles are alternately and equally present throughout the circumference. The direction of the main magnetic flux generated by the stator 10 (magnets) is along the axis C of the rotation shaft 21. The direction of the main magnetic flux is generated in the direction corresponding to the magnetic poles of the magnets 11. The stator 10 (magnets 11) 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 of 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 of the rotating shaft 21. The direction of the main magnetic flux generated by the rotor 20 corresponds to the direction of the current flowing through the coil 22.

[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 of the rotating shaft 21. Specifically, the coil 22 of the rotor 20 and the stator 10 are opposite to each other in the direction of the axis C of the rotating shaft 21. That is, the coil 22 and the stator 10 are arranged in the direction of the axis C of the rotating shaft 21.

[0052] The rotating shaft 21 is a shaft containing 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 (Stainless Steel). 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, 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. 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 of the rotating shaft 21 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 fan. The second end 21b of the rotating shaft 21 is the output-opposite end (output-opposite shaft). The second end 21b of the rotating shaft 21 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 second bracket 102. Specifically, the second bearing 92 is fixed to a recess provided in the second bracket 102.

[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 11 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. The first bracket 101 and the second bracket 102 may also be made of resin. 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 metal. Specifically, the first bracket 101 and the second bracket 102 are made of metal sheet. The first bracket 101 is formed into a predetermined three-dimensional shape by performing a predetermined stamping process or the like on the metal sheet. The second bracket 102 is a flat, plate-shaped metal sheet.

[0060] Figure 3 The 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. Each coil 22 is 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 of the rotation shaft 21. Specifically, each coil 22 is wound into a flat shape. The coil faces of each coil 22 are arranged in an orientation facing the axis C of the rotation shaft 21.

[0061] Each of the multiple coils 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 the insulated wire wound in a planar shape. Specifically, each of the multiple coils 22 is composed of one or more coil layers, for example, the insulated wire substantially wound into a fan shape when viewed from above. The multiple coils 22 thus configured are arranged to surround the rotation shaft 21 when viewed from the axis C of rotation.

[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. Thus, current flows to the multiple coils 22 via the commutator segments 31 that are in contact with the brushes 40.

[0063] Multiple coils 22 are covered by molding resin 23. That is, the multiple coils 22 are resin molded. Therefore, the multiple coils 22 are integrally formed together with the molding resin 23 by being covered by it. 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 resin (BMC (Bulk Molding Compound)). 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 molded in a thin shape using resin molding. As a result, a thin motor 1 with low inductance and a flattened profile can be achieved.

[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 shaft 21. Specifically, the plurality of commutator segments 31 are arranged in a ring shape along the rotation direction of the rotation shaft 21 in a manner that surrounds the rotation shaft 21. Each commutator segment 31 is a long strip-shaped member extending along the length direction of the rotation shaft 21.

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

[0068] As an example, the commutator 30 is a molded commutator. The commutator 30 is a structure formed by molding multiple commutator segments 31 using molding resin 23. In this case, the multiple commutator segments 31 are embedded in the molding resin 23 with their surfaces exposed. The molding resin 23 is the commutator body. The molding resin 23 is a substantially cylindrical member 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] like Figure 3 As shown, at least one brush 40 is in contact with the commutator 30. Specifically, the front end of the brush 40 is in contact with the commutator segment 31 of the commutator 30. Since the commutator 30 rotates by the rotation of the rotating shaft 21, the brush 40 continuously contacts all the commutator segments 31 in sequence.

[0070] like Figure 3 and Figure 5 As shown, the brush 40 includes a front end surface 40a that contacts the commutator 30 and a rear end surface 40b that is opposite to the front end surface 40a.

[0071] The front end face 40a of the brush 40 is the end face of the front end of one end of the brush 40 in the longitudinal direction. The front end face 40a is the top end face of the brush 40 on the rotating shaft 21 side (radially inward). The front end face 40a is the contact surface that contacts the commutator segment 31 of the commutator 30.

[0072] The rear end face 40b of the brush 40 is the end face of the rear end portion, which is the other end of the brush 40 in the longitudinal direction. The rear end face 40b is the top end face of the brush 40 on the side opposite to the side of the rotation shaft 21 (radially outward). The rear end face 40b is the contact surface that contacts the brush spring 50. Specifically, the spiral portion 51 of the brush spring 50 contacts the rear end face 40b.

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

[0075] In this embodiment, multiple brushes 40 are provided. Specifically, as shown... Figures 3-5 As shown, the motor 1 is provided with two brushes 40. The two brushes 40 are arranged opposite each other with a gap between them and the commutator 30. That is, the two brushes 40 are arranged at a 180° interval along the rotation direction of the rotor 20. Therefore, the two brushes 40 are arranged in a straight line. The angle between the length directions of the two brushes 40 is 180°. Therefore, the commutator 30 is pressed in one axial direction by the two brushes 40 arranged in a straight line. Furthermore, the number of brushes 40 is not limited to two.

[0076] The brush 40 is in constant contact with the commutator segments 31 of the commutator 30 due to the pressing force from the brush spring 50. That is, the brush 40 is pressed against the commutator 30 by the brush spring 50. Thus, the brush 40 is configured to slide in contact with the commutator 30 due to the pressing force from the brush spring 50, and is capable of moving radially in a direction intersecting the axis C of the rotating shaft 21 due to wear with the commutator 30.

[0077] like Figure 5 and Figure 6 As shown, two brushes 40 are disposed on the brush holder 60. Specifically, the two brushes 40 are disposed on the brush holder 60 such that their length direction is orthogonal to the axis C of the rotating shaft 21 (that is, the radial direction of the rotation of the rotating shaft 21).

[0078] The number of brush springs 50 is determined by the number of brushes 40. In this embodiment, 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 elastic force (spring restoring force), exerting a force on the brush 40 toward the commutator 30. The brush spring 50 is a constant load spring. Therefore, the brush spring 50 applies a uniform load to the brush 40. In other words, the brush spring 50, as a constant load spring, applies a uniform pressing force to the brush 40.

[0080] The brush spring 50 is made of strip-shaped wire. The brush spring 50 is a spiral spring. For example... Figure 5 and Figure 6 As shown, the brush spring 50 has a spiral portion 51 (coil portion) formed by spirally winding a strip of wire. The brush spring 50 is constructed, for example, using a strip of wire made of a metal material such as a steel plate.

[0081] Specifically, the brush spring 50 is composed of a long, strip-shaped metal plate. Therefore, the spiral portion 51 is the part of the brush spring 50 where the long, strip-shaped metal plate is spirally wound multiple times in only one direction. For the brush spring 50, when one end of the wire is pulled from the spiral portion 51, a force (spring restoring force) is generated that attempts to return it to its original spiral state.

[0082] like Figure 3 and Figure 5 As shown, the brush spring 50 applies a pressing force (load) to the brush 40 using the spiral portion 51 that contacts the rear end face 40b of the brush 40. In other words, the brush spring 50 presses the brush 40 against the commutator 30 using the spiral portion 51. Specifically, the brush spring 50 applies a pressing force to the brush 40 using the spring restoring force of the spiral portion 51, which is in a state of spring restoring force contact with the rear end face 40b of the brush 40. Thus, the brush 40 is forced towards the commutator 30.

[0083] From an external power source located outside the motor 1 via Figure 2 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. The external power supply supplies a predetermined input voltage to the motor 1. The external power supply is a DC power source that supplies a DC 12V input voltage to the motor 1.

[0084] Power terminal 80 receives power from an external power source 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. Figure 4 and Figure 6 As shown, the power terminal 80 and the brush 40 are electrically connected by a braided wire 41. The braided wire 41 is fixed to the brush 40. Specifically, one end of the braided wire 41 is fixed to the brush 40, and the other end of the braided wire 41 is connected to the power terminal 80. The braided wire 41 is fixed to the brush 40, for example, by extending from the side of the brush 40. The braided wire 41 and the power terminal 80 are joined, for example, using solder or the like.

[0085] like Figure 4 and Figure 6 As shown, the power terminal 80 is fixed to the brush holder 60. Specifically, the power terminal 80 is fixed to the brush holder 60 by partially pressing it into an insertion hole provided in the brush holder 60. The power terminal 80 is electrically connected to an external power source via a power cord.

[0086] The motor 1 is provided with two power supply terminals 80. The two power supply terminals 80 receive DC power from an external power source. In this case, one of the two power supply terminals 80 is a positive-side power supply terminal (high-voltage side terminal) connected to the positive side of the DC power source. The other power supply terminal 80 is a negative-side power supply terminal (low-voltage side terminal) connected to the negative side of the DC power source.

[0087] Alternatively, a noise reduction capacitor can be connected to both power supply terminals 80. In this case, the capacitor is connected to the two power supply terminals 80 in parallel. This allows noise generated by the motor 1 to be suppressed.

[0088] like Figure 3 and Figure 4 As shown, the brush 40 is disposed on 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 holds 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 main surface of the second bracket 102 from the outside.

[0089] The brush holder 60 is made of an insulating resin material. The brush holder 60 is a resin molded article integrally formed from the insulating resin material. For example, the resin material constituting the brush holder 60 is phenolic resin. However, it is not limited to this.

[0090] like Figures 3-6 As shown, the brush holder 60 has a brush receiving portion 60a that serves as a spatial area for receiving the brushes 40. The brush receiving portion 60a is formed as a concave portion. The number of brush receiving portions 60a varies depending on the number of brushes 40. Two brush receiving portions 60a are formed in the brush holder 60. The two brush receiving portions 60a are longer in a direction orthogonal to the axis C of the rotation shaft 21 (i.e., radially), and their cross-sectional shape is formed as a rectangular concave shape.

[0091] like Figure 3 and Figure 6 As shown, the brush housing 60a houses both the brush 40 and the brush spring 50. Therefore, the length of the brush housing 60a 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 face 40b of the brush 40. That is, the brush spring 50 is disposed in the brush housing 60a such that the spiral portion 51 is located on the side opposite to the side where the commutator 30 is located within the brush housing 60a.

[0092] The brush spring 50 is configured such that the spiral axis of the spiral portion 51 is aligned with the axis C of the rotation shaft 21. That is, the spiral surface (coil surface) of the spiral portion 51 is substantially orthogonal to the axis C of the rotation shaft 21. The brush spring 50 is housed in the brush housing portion 60a with the spiral portion 51 placed horizontally.

[0093] like Figure 5 and Figure 6 As shown, the brush spring 50 has a lead wire 52 extending from the spiral section 51. The brush spring 50 is fixed to the brush holder 60 by the partial support of the lead wire 52.

[0094] The brush 40, housed in the brush housing 60a, slides within the brush housing 60a under the pressure of the brush spring 50. The brush 40, pressed by the brush spring 50, wears down due to friction between its front end face 40a and the commutator segment 31, thus moving towards the commutator 30 within the brush housing 60a under the pressure of the brush spring 50. In other words, through the wear of the brush 40, its rear end face 40b moves radially towards the axis C of the rotating shaft 21. Therefore, as... Figure 7 As shown, the spiral portion 51 of the brush spring 50, which is in contact with the rear end face 40b of the brush 40, also moves in the direction (radial) toward the axis C of the rotating shaft 21.

[0095] like Figure 3 and Figure 4 As shown, a cover plate 70 is provided to cover the brush 40 housed in the brush housing 60a. The cover plate 70 covers not only the brush 40 but also the brush spring 50. The cover plate 70 is fixed to the brush holder 60 by partially pressing it into the brush holder 60. The cover plate 70 is made of a metal material such as brass or stainless steel (SUS). The cover plate 70 is made of a plate-shaped metal sheet. The cover plate 70 is formed by bending or stamping a metal sheet that has been punched into a predetermined shape.

[0096] like Figures 5-7 As shown, the brush holder 60 has three support portions—a first support portion 61, a second support portion 62, and a third support portion 63—that serve as support points for supporting the brush spring 50. The first support portion 61, the second support portion 62, and the third support portion 63 are the wall portions of the brush holder 60.

[0097] like Figure 7 As shown, the first support portion 61 is located on the moving path of the scroll portion 51 of the brush spring 50. When the scroll portion 51 of the brush spring 50 moves toward the rotating shaft 21 due to wear of the brush 40, the first support portion 61 supports the scroll portion 51. That is, as... Figure 6 As shown, the first support portion 61 does not contact the spiral portion 51 before the brush 40 wears. Figure 7 As shown, when the brush 40 wears and the scroll portion 51 slides together with the brush 40, the scroll portion 51 abuts against the first support portion 61, thereby supporting the scroll portion 51. When the scroll portion 51 abuts against the first support portion 61, the spring load generated by the brush spring 50 becomes zero. That is, the pressing force exerted by the brush spring 50 on the brush 40 becomes zero, and the sliding of the brush 40 stops. The zero spring load can also include a state where the brush spring 50 has a pressing force on the brush 40, but the brush 40 does not move in the direction of the rotation axis 21.

[0098] In this embodiment, the first support portion 61 is inclined relative to the moving direction of the scroll portion 51 of the brush spring 50 (the sliding direction of the brush 40). Specifically, the first support portion 61 is a concave curved surface relative to the scroll portion 51 of the brush spring 50. As an example, the first support portion 61 is a curved surface having the same curvature as the curved surface constituting the outer surface of the scroll portion 51. Furthermore, the first support portion 61 is not limited to a curved surface, and may also be a planar inclined surface inclined relative to the moving direction of the scroll portion 51 of the brush spring 50. For example, the first support portion 61 may also be a chamfered surface.

[0099] like Figure 6 and Figure 7 As shown, the second support portion 62 and the third support portion 63 support portions of the lead wire 52 extending from the spiral portion 51 of the brush spring 50. Because the lead wire 52 is supported by the second support portion 62 and the third support portion 63, the brush spring 50 is held in place by the brush holder 60 and thus fixed. Furthermore, even if the brush 40 wears and slides towards the commutator 30, the portion of the lead wire 52 supported by the second support portion 62 and the third support portion 63 will not roll back into the spiral portion 51, but will remain held in place by the second support portion 62 and the third support portion 63.

[0100] like Figure 5 As shown, the lead wire 52 extending from the spiral portion 51 of the brush spring 50 is bent at both the first bend 50a and the second bend 50b. The second bend 50b is located closer to the spiral portion 51 than the first bend 50a.

[0101] By bending the lead wire 52 in this way, the brush spring 50 has: a first portion 52a, which is a portion of the lead wire 52 located on the top side (outer end side) of the first bend portion 50a; and a second portion 52b, which is a portion of the lead wire 52 between the first bend portion 50a and the second bend portion 50b. The plate-shaped wire constituting the first portion 52a is erected on the plate-shaped wire constituting the second portion 52b.

[0102] In this embodiment, the lead wire 52 is bent at the first bend 50a with the first portion 52a facing the rotating shaft 21 side (commutator 30 side). Specifically, at the first bend 50a, the lead wire 52 is bent at an acute angle of less than 90°. At the second bend 50b, the lead wire 52 is bent at a right angle of 90°. Therefore, the cross-sections of the first portion 52a and the second portion 52b are substantially V-shaped.

[0103] like Figure 7 As shown, the second support portion 62 of the brush holder 60 supports the lead wire 52 by locking the first portion 52a of the lead wire 52. The second support portion 62 and the first portion 52a of the lead wire 52 are in line contact (at... Figure 7 (Point contact in the top view). The second support portion 62 has a planar support surface that contacts the lead wire 52. Specifically, a bent piece 52a1 is formed at the top end of the first portion 52a of the lead wire 52. The planar second support portion 62 supports the root portion (bent portion) of the bent piece 52a1.

[0104] like Figure 7 As shown, the third support portion 63 supports the lead wire 52 by locking the second portion 52b of the lead wire 52. The third support portion 63 and the second portion 52b of the lead wire 52 are in surface contact (at... Figure 7 (Line contact is shown in the top view). The third support portion 63 has a planar support surface that contacts the lead wire 52. Specifically, the planar second support portion 62 supports the planar second portion 52b of the lead wire 52.

[0105] The second support portion 62 is located on the opposite side (outer side) of the first support portion 61 from the side opposite to the rotating shaft 21 in the sliding direction of the brush 40. That is, the first support portion 61 is located on the side closer to the rotating shaft 21 (inner side) in the sliding direction of the brush 40 than the second support portion 62. The third support portion 63 is located on the side closer to the rotating shaft 21 than the first support portion 61 in the sliding direction of the brush 40. That is, the first support portion 61 is located between the second support portion 62 and the third support portion 63 in the sliding direction of the brush 40.

[0106] The brush holder 60 has slots for inserting the lead wire 52. Specifically, the brush holder 60 has a first slot 60b for inserting the first portion 52a of the lead wire 52 and a second slot 60c for inserting the second portion 52b of the lead wire 52. That is, the first slot 60b and the second slot 60c are storage portions for storing the wire constituting the brush spring 50.

[0107] The first groove 60b and the second groove 60c are connected to form a single groove. Specifically, the groove formed by the first groove 60b and the second groove 60c is formed by a right-angle bend with the angle between the first groove 60b and the second groove 60c being 90°.

[0108] The first groove 60b has a pair of opposing inner side surfaces (inner wall surfaces). The first portion 52a of the lead wire 52 is sandwiched between the pair of inner side surfaces constituting the first groove 60b. The first portion 52a is inserted into the first groove 60b in an inclined position relative to the length direction of the first groove 60b. Therefore, the second support portion 62, which serves as a support surface, becomes one of the inner side surfaces of the pair of inner side surfaces constituting the first groove 60b. As described above, the second support portion 62 makes line contact with the root portion of the bent piece 52a1 of the first portion 52a of the lead wire 52.

[0109] A curved piece 52a1 formed at the top end of the first portion 52a is embedded in the first groove 60b. Specifically, the curved piece 52a1 is embedded in the first groove 60b in the groove width direction. At this time, before the brush 40 wears, the curved piece 52a1 may contact each of the pair of inner surfaces constituting the first groove 60b, or it may only contact one of the pair of inner surfaces constituting the first groove 60b (the second support portion 62). That is, the top end of the curved piece 52a1 may not contact the other inner surface of the pair of inner surfaces constituting the first groove 60b (the surface opposite the second support portion 62).

[0110] The second groove 60c has a pair of opposing inner surfaces (inner wall surfaces). The second portion 52b of the lead wire 52 is sandwiched between the pair of inner surfaces constituting the second groove 60c. Specifically, the third support portion 63, which serves as a support surface, becomes one of the inner surfaces of the pair of inner surfaces constituting the second groove 60c. The third support portion 63 is in contact with the surface of the second portion 52b of the lead wire 52.

[0111] One of the pair of inner surfaces constituting the second groove 60c does not contact the lead wire 52, but may contact it. The other inner surface constituting the second groove 60c has a protrusion 64 that protrudes toward the lead wire 52 inserted into the second groove 60c. By providing the protrusion 64, the second portion 52b of the lead wire 52 inserted into the second groove 60c can be supported in a state where it is sandwiched between the third support portion 63 and the second portion 52b.

[0112] Reference Figure 7 Use Figure 8A , Figure 8B and Figure 9 The method of placing the brush 40 and brush spring 50 on the brush holder 60 is explained. Figure 8A and Figure 8BThis is a diagram showing the structure of the brush spring 50 assembled before the brush holder 60 in the electric motor 1 of the embodiment. Figure 8A This is a 3D diagram of brush spring 50. Figure 8B This is a side view of the brush spring 50. Figure 9 This diagram illustrates the configuration of the electric motor 1 according to the embodiment, where the brush spring 50 is assembled onto the brush holder 60. Figure 9 In the middle, the dashed circle represents Figure 8A , Figure 8B The state of the spiral section 51 of the brush spring 50 shown.

[0113] Figure 8A , Figure 8B The brush spring 50 shown is in a state where no stress is applied to the brush spring 50. Figure 8A , Figure 8B The brush spring 50, as shown, is provided in the brush storage section 60a of the brush holder 60.

[0114] Specifically, such as Figure 9 As shown, the brush spring 50 is fixed to the brush holder 60 by supporting the lead wire 52 of the brush spring 50 on the second support portion 62 and the third support portion 63 of the brush holder 60. That is, the brush spring 50 is fixed to the brush holder 60 by hooking the first portion 52a and the second portion 52b of the lead wire 52 onto the second support portion 62 and the third support portion 63, respectively. In this case, the first portion 52a of the lead wire 52 is inserted into the first slot 60b and locked to the second support portion 62, and the second portion 52b of the lead wire 52 is inserted into the second slot 60c and locked to the third support portion 63.

[0115] At this time, the spiral portion 51 of the brush spring 50 abuts against the first support portion 61, becoming slightly pushed out by the first support portion 61. That is, the spiral portion 51 abutting against the first support portion 61 is in a state different from that before the brush spring 50 was assembled onto the brush holder 60. Figure 9 The dotted circle (the circle) has been slightly moved toward the side opposite to the rotation axis 21 (commutator 30). In other words, the scroll section 51 is pressed toward the side opposite to the rotation axis 21 (outer side).

[0116] Thus, when the brush spring 50 is assembled onto the brush holder 60, the brush spring 50 is supported by the brush holder 60 at three points: the first support portion 61, the second support portion 62, and the third support portion 63. In other words, the brush spring 50 is supported by the brush holder 60 at three points. Therefore, during assembly, the brush spring 50 is held in place by its own spring force within the brush holder 60. Consequently, the assemblability of the brush spring 50 is improved.

[0117] At this time, in such Figure 8BThe length (spring leg length) of the first part 52a of the lead wire 52 of the brush spring 50 assembled before the brush holder 60 is shown as L. Figure 9 When the length of the first groove 60b into which the first part 52a is inserted is set to W, it is better for W < L.

[0118] By doing so, when the brush spring 50 is assembled onto the brush holder 60, it is possible to prevent the inner side of the second portion 52b, inserted into the second groove 60c, from collapsing towards the commutator 30 side (rotation shaft 21 side). In other words, it is possible to prevent the second portion 52b from separating from the third support portion 63. As a result, as... Figure 9 As shown, when the brush spring 50 is assembled onto the brush holder 60, it can maintain three-point support for the brush spring 50 at three locations: the first support portion 61, the second support portion 62, and the third support portion 63.

[0119] like Figure 8B As shown, in the brush spring 50 assembled before the brush holder 60, when the angle (foldback angle) formed by the first part 52a and the second part 52b of the lead wire 52 of the brush spring 50 is set as α, it is preferable that angle α is an acute angle. That is, α < 90° is preferable. Figure 9 As shown, after assembling the brush spring 50 onto the brush holder 60, when the angle (foldback angle) formed by the first part 52a and the second part 52b of the lead wire 52 of the brush spring 50 is set as β, it is better to satisfy the relationship α≤β≤90°.

[0120] By doing so, it is possible to prevent the lead wire 52 of the brush spring 50 inserted into the first slot 60b and the second slot 60c from disengaging from the first slot 60b and the second slot 60c. That is, in the state before the spiral portion 51 of the brush spring 50 abuts against the first support portion 61 (the state in which the lead wire 52 of the brush spring 50 is extended), the lead wire 52 inserted into the first slot 60b and the second slot 60c is directed towards the brush 40 ( Figure 9 When a tensile force is applied (in the direction below the paper surface), the brush spring 50 may disengage from slots 1 60b and 2 60c. However, by setting the relationship α≤β≤90°, a force is applied to resist the disengagement of the brush spring 50. This prevents the lead wire 52 inserted into slots 1 60b and 2 60c from disengaging from them.

[0121] In particular, in this embodiment, a bent piece 52a1 is formed at the top end of the first portion 52a. Therefore, when a tensile force is applied to the lead wire 52 in the direction toward the brush 40 before the spiral portion 51 abuts against the first support portion 61, the bent piece 52a1 embedded in the first groove 60b is engaged within the first groove 60b. This more reliably prevents the lead wire 52 from disengaging from the first groove 60b and the second groove 60c.

[0122] Next, after holding the brush spring 50 in the brush holder 60, the rear end face 40b of the brush 40 with the braided wire 41 attached is brought into contact with the spiral portion 51 of the brush spring 50, and the brush 40 is placed in the brush receiving portion 60a. At this time, the front end of the brush 40 extends from the brush receiving portion 60a and exists in the area where the commutator 30 is disposed. At this time, the braided wire 41 attached to the brush 40 can also be connected to the power terminal 80.

[0123] Next, from Figure 9 From the state shown, the brush 40 is moved in the direction (outward) away from the rotating shaft 21. Specifically, the brush 40 is moved inward toward the brush housing 60a until the front end face 40a of the brush 40 is located at the front end of the brush housing 60a.

[0124] At this time, the spiral portion 51 of the brush spring 50, which abuts against the rear end face 40b of the brush 40, moves inward toward the brush receiving portion 60a as the brush 40 moves. Meanwhile, since the lead wire 52 of the brush spring 50 is secured to the second support portion 62 and the third support portion 63 of the brush holder 60, as the brush 40 moves, the strip-shaped wire constituting the brush spring 50 is led out from the spiral portion 51 along the inner side of the brush receiving portion 60a. In other words, the brush 40 moves inward while bearing a gradually increasing spring force from the spiral portion 51 of the brush spring 50.

[0125] Next, the rotor 20, on which the commutator 30 is mounted, is placed on the brush holder 60. Thus, as... Figure 6 As shown, the front end face 40a of the brush 40 contacts the commutator 30, and the brush 40 is held in place. That is, the brush 40 is positioned in the brush holder 60 in a state where it receives pressure from the brush spring 50.

[0126] In the electric motor 1 configured as described above, when power is supplied to the power terminal 80, the power supplied to the power terminal 80 is also supplied to the brushes 40. As a result, the armature current (drive current) flows through the commutator 30, which is in contact with the brushes 40, to the coil 22, generating magnetic flux in the rotor 20 (coil 22). Furthermore, 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 through the coil 22 is switched according to the positional relationship between the commutator segments 31 and the brushes 40 when they are in contact. Thus, by switching the direction of current flow, a rotational force in a constant 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.

[0127] At this time, the brush 40, held in the brush holder 60, is pressed against the commutator 30 by the brush spring 50. Therefore, as the rotor 20 rotates, the front end face 40a of the brush 40 wears down due to friction with the commutator segments 31 of the commutator 30. That is, the brush 40 shortens in length due to wear against the commutator segments 31. Consequently, the rear end face 40b of the brush 40 moves towards the commutator 30 within the brush housing 60a as the brush 40 wears down. At this time, as the brush 40 shortens due to wear, the wire constituting the brush spring 50 is wound in a spiral shape 51. That is, the lead wire 52 extending from the spiral shape 51 shortens, as... Figure 7 As shown, the scroll section 51 moves toward the commutator 30. Figure 7 In the diagram, the single-dot dashed line represents the trajectory of the center O of the volute 51 as it moves due to the wear of the brush 40.

[0128] like Figure 7 As shown by the dashed line, this is the intermediate stage between the initial stage when brush 40 begins to wear and the final stage when brush 40 is nearing the end of its lifespan. Figure 7 When the brush spring 50 is between the two middle scrolls 51 of the four scrolls 51, the scrolls 51 of the brush spring 50 move linearly toward the rotating shaft 21. Therefore, as Figure 10 As shown, during this intermediate stage, even if the brush 40 wears, the spring load generated by the brush spring 50 remains constant and does not change. Figure 10 This is a diagram schematically showing the change in the spring load of the brush spring 50 in the electric motor 1 of the embodiment relative to the amount of brush wear.

[0129] On the other hand, such as Figure 7 As shown by the dashed line, this is the initial stage when brush 40 begins to wear. Figure 7 (between the two leftmost of the four volutes 51) and the final stage when the brush 40 is nearing the end of its lifespan ( Figure 7When the brush spring 50 is between the two rightmost of the four scroll sections 51, the scroll section 51 does not move in a straight line, but moves in a turning manner. That is, the scroll section 51 is offset to the left or right relative to the center line along the length direction of the brush 40. Therefore, as Figure 10 As shown, in the initial and final stages, the spring load applied by the brush spring 50 to the brush 40 is not constant, but gradually decreases as the brush 40 wears.

[0130] Thus, even when a constant load spring is used as the brush spring 50, the spring load is not constant during the final stage of the brush 40's lifespan (end of brush life). Therefore, in this final stage, not only does electrical wear caused by sparking increase rapidly, but the pressing force applied by the brush spring 50 to the brush 40 becomes insufficient or unstable, sometimes leading to a decline in motor quality. Furthermore, this decline in motor quality cannot be visually identified from the outside of the motor. Therefore, from the perspective of motor users, there are calls for improved ease of use, such as difficulty in knowing when the motor should be replaced.

[0131] Therefore, in the electric motor 1, a first support portion 61 is provided in the brush holder 60. When the spiral portion 51 of the brush spring 50 moves toward the rotating shaft 21 (commutator 30) due to wear of the brush 40, this first support portion 61 supports the spiral portion 51. In the electric motor 1, the spring load of the brush spring 50 becomes zero when the spiral portion 51 abuts against the first support portion 61. That is, when the wear of the brush 40 reaches a predetermined amount, the pressing force applied by the brush spring 50 to the brush 40 immediately becomes zero, forcibly stopping the sliding of the brush 40.

[0132] According to this structure, even if the brush spring 50 is a constant load spring, the period of inconsistent spring load can be shortened. Therefore, it is possible to suppress the unstable wear of the brush 40 at the end of its brush life. Consequently, the quality of the motor 1 at the end of the brush life can be improved.

[0133] In this embodiment, such as Figure 10 As shown, the moment when the spring load generated by the brush spring becomes zero when the vortex portion 51 abuts against the first support portion 61 of the brush holder 60 is the middle of the period when the spring load of the brush spring 50 is not constant (the final stage period) after the period when the spring load of the brush spring 50 is constant (the middle period).

[0134] Therefore, the duration of the final stage of the motor 1 at the end of its brush life can be shortened. Consequently, the unstable wear of the brush 40 at the end of its brush life can be suppressed. Therefore, the quality of the motor 1 at the end of its brush life can be improved.

[0135] By changing the position of the first support portion 61 of the brush holder 60, the timing of contact between the scroll portion 51 and the first support portion 61 (i.e., the lifespan of the motor 1) can be changed. The timing of contact between the scroll portion 51 and the first support portion 61 can also be changed depending on the type of motor 1. In this case, the timing of contact between the scroll portion 51 and the first support portion 61 can also be... Figure 10 The changes are shown in the final stage. However, it is not limited to this. For example, the moment when the volute 51 abuts against the first support 61 could also be... Figure 10 The middle stage shown is the mid-term. Therefore, although the lifespan of motor 1 is shortened, the period of inconsistent spring load on the brush spring 50 at the end of its lifespan can be completely eliminated. Thus, the quality of motor 1 at the end of its brush lifespan can be further improved.

[0136] (Variation example)

[0137] The electric motor 1 of this disclosure has been described above based on the embodiments. However, this disclosure is not limited to the above embodiments. Figure 11 This is a top view showing the structure of the brush holder 60A of the electric motor 1 in Modified Example 1. Figure 12 This is a top view showing the structure of the brush holder 60B of the electric motor 1 in Modified Example 2. Figure 13 This is a top view showing the structure of the brush holder 60C of the electric motor 1 in Modified Example 3. Figure 14 The figure shows a first modified example of a brush spring 50A, which is a constant load spring. Figure 15 The figure shows a second variation of the brush spring 50B, which is a constant load spring. Figure 16 This indicates that they are used separately. Figure 14 and Figure 15 A top view of the structure of the brush holder 60D of the motor 1 in the modified example 4 with brush springs 50A and 50B shown. Figure 17 This is a top view showing the structure of the brush holder 60E of the electric motor 1 in Modified Example 5. Figure 18A and Figure 18B This is a diagram showing the structure of the other brush springs 50C assembled before the brush holder in the motor 1 of Modified Example 6. Figure 18A This is a 3D diagram of a 50C brush spring. Figure 18B This is a side view of the brush spring 50C. Figure 19 This is a diagram showing the situation in the motor 1 of Modified Example 6 where another brush spring 50 is assembled to the brush holder 60.

[0138] For example, in this embodiment, the first support portion 61 of the brush holder 60 is a concave curved surface relative to the spiral portion 51 of the brush spring 50. However, it is not limited to this. Specifically, it can also be like... Figure 11As shown in the brush holder 60A, the first support portion 61A is a curved surface that is convex relative to the spiral portion 51 of the brush spring 50. Alternatively, it can be like... Figure 12 As shown in the brush holder 60B, the first support portion 61B is a right-angled corner (sharp corner).

[0139] Furthermore, in this embodiment, the first support portion 61 of the brush holder 60 is located on the side closer to the rotation axis 21 (commutator 30 side) than the second support portion 62 in the sliding direction of the brush 40. However, it is not limited to this. For example, it can also be like... Figure 13 As shown in the brush holder 60C, the first support portion 61C is located on the side opposite to the rotating shaft 21 in the sliding direction of the brush 40, compared to the second support portion 62. According to this structure, compared to the above embodiment, while accelerating the lifespan of the motor, unstable operation of the motor 1 can be suppressed. Therefore, the quality of the motor 1 can be further improved.

[0140] In this embodiment, the lead wire 52 of the brush spring 50 is bent at both the first bend 50a and the second bend 50b. However, it is not limited to this. For example, it can also be bent as follows: Figure 14 The brush spring 50A shown is... Figure 15 As shown in the brush spring 50B, the lead wire 52 is bent at three points: the first bend 50a, the second bend 50b, and the third bend 50c. In this case, the third bend 50c is located between the first bend 50a and the second bend 50b. The lead wire 52 has a third portion 52c between the first portion 52a and the second portion 52b. The lead wire 52 is bent at the first bend 50a with the first portion 52a facing the side opposite to the rotation axis 21.

[0141] exist Figure 14 In the brush spring 50A shown, the lead wire 52 is bent such that the first portion 52a and the second portion 52b form an acute angle or a right angle, and the second portion 52b and the third portion 52c form a right angle. Figure 14 In the brush spring 50A shown, the angle α (return angle) formed by the first part 52a and the third part 52c is α≤90°.

[0142] exist Figure 15 In the brush spring 50B shown, the lead wire 52 is bent such that the first portion 52a and the third portion 52c form an acute angle or a right angle, and the third portion 52c and the second portion 52b form an acute angle or a right angle. Figure 15 In the brush spring 50B shown, the angle γ (return angle) formed by the second part 52b and the third part 52c is γ≤90°.

[0143] Figure 14The brush spring shown is 50A or Figure 15 The brush spring 50B shown can be assembled into Figure 16 The brush holder shown is 60D.

[0144] At this time, the lead wires 52 of brush springs 50A and 50B are bent at the first bend 50a with the first portion 52a facing the side opposite to the rotating shaft 21. In addition to the first portion 52a and the second portion 52b, the lead wire 52 also has a third portion 52c. Therefore, in Figure 16 In the brush holder 60D shown, in the sliding direction of the brush 40, the second support portion 62D is located on the side opposite to the side of the rotation axis 21 (outer side) to the third support portion 63. The brush holder 60D has a fourth support portion 65 that supports the third portion 52c of the lead wire 52.

[0145] In such Figure 14 As shown, in the brush spring 50A assembled before the brush holder 60D, the angle (foldback angle) formed by the first part 52a and the third part 52c of the lead wire 52 of the brush spring 50A is set as α, as follows. Figure 16 As shown, when the angle (foldback angle) between the first part 52a and the third part 52c of the lead wire 52 of the brush spring 50A after assembling the brush spring 50A onto the brush holder 60D is set to β, it is better to satisfy the relationship α≤β≤90°. By doing so, it is possible to prevent the lead wire 52 of the brush spring 50A from detaching from the brush holder 60D.

[0146] In addition, in such Figure 15 As shown, in the brush spring 50B assembled before the brush holder 60D, the angle (foldback angle) formed by the second part 52b and the third part 52c of the lead wire 52 of the brush spring 50B is set as γ, as follows. Figure 16 As shown, when the angle (foldback angle) between the second part 52b and the third part 52c of the lead wire 52 of the brush spring 50B after assembling the brush spring 50B onto the brush holder 60D is set to δ, it is better to satisfy the relationship γ≤δ≤90°. By doing so, it is possible to prevent the lead wire 52 of the brush spring 50B from detaching from the brush holder 60D.

[0147] Furthermore, in the above embodiment, the third support portion 63 of the brush holder 60D contacts the lead wire 52 surface of the brush spring 50. However, it is not limited to this. For example, it can also be like... Figure 17 As shown in the brush holder 60E, a protrusion 63a is provided in the third support portion 63, and the third support portion 63 contacts the lead wire 52 of the brush spring 50.

[0148] Furthermore, in the above embodiment, the brush holder 60 for holding the brush spring 50 is used as the retainer. However, it is not limited to this. Specifically, the retainer for holding the brush spring 50 may be a component other than the brush holder 60 for holding the brush 40. That is, it is not necessary for one retainer to serve as both the retainer for holding the brush 40 and the retainer for holding the brush spring 50; instead, the retainer for holding the brush 40 and the retainer for holding the brush spring 50 may be separate.

[0149] Furthermore, in the above embodiment, the rear end face 40b of the brush 40 is provided as a plane perpendicular to the sliding direction of the brush 40. However, it is not limited to this. For example, the rear end face 40b of the brush 40 may also be an inclined surface that is inclined relative to the sliding direction of the brush 40. A recess may also be formed in the portion of the rear end face 40b of the brush 40 where the spiral portion 51 of the brush spring 50 abuts. As a result, a portion of the spiral portion 51 enters the recess, so that when the brush 40 slides, the spiral portion 51 is stably held on the rear end face 40b of the brush 40.

[0150] Furthermore, in the above embodiment, the rotating shaft 21 is supported by two bearings, a first bearing 91 and a second bearing 92. However, it is not limited to this. Specifically, the rotating shaft 21 may also be supported by a single bearing.

[0151] 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, as in the above embodiment, by making it a coreless motor, it is possible to achieve a motor 1 with lower inductance and a thinner profile.

[0152] 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 can be a stator composed of permanent magnets and an iron core, or it can be an armature composed of stator windings and an iron core without using permanent magnets.

[0153] Furthermore, in the above embodiment, the motor 1 is a flat, plate 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.

[0154] Furthermore, in the above embodiment, the direction of the main magnetic flux generated by the stator 10 and the rotor 20 is the direction of the axis C of the rotating shaft 21. However, it is not limited to this. 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 axis C of the rotating shaft 21 (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.

[0155] In the above embodiment, the brush spring 50 has a bent tab 52a1 at the top end of the lead wire 52. However, the brush spring 50 is not limited to this arrangement. Specifically, as... Figure 18A , Figure 18B and Figure 19 As shown, the brush spring 50C can also be configured without a bending tab at the tip of the lead wire 52B. When using the brush spring 50C of this modified example, Figure 18B The angle α1 between the first part 52a and the second part 52b shown expands to... Figure 19 The first part 52a is mounted on the second support 62 at an angle β1 formed by the first part 52a and the second part 52b. In this case, the angle between the first part 52a and the second part 52b is such that α1 < β1. As a result, the first part 52a exerts an elastic force that wants to return to the second part 52b. The first part 52a is held in place by the second support 62 by this elastic force.

[0156] 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 various other electrical devices, such as electric fans used in electric vacuum cleaners.

[0157] Furthermore, this disclosure also includes various modifications conceived by those skilled in the art to the above embodiments and variations, or methods implemented by arbitrarily combining the constituent elements and functions of the embodiments without departing from the spirit of this disclosure. This disclosure also includes methods that arbitrarily combine two or more claims from the multiple claims recited in the claims at the time of filing of this application, to the extent that they are not technically contradictory. For example, when a referenced claim recited in the claims at the time of filing of this application is designated as a plurality of claims or a plurality of referenced-multiple claims, to the extent that it is not technically contradictory, the combination of all claims included in such plurality of claims or plurality of referenced-multiple claims is also included in this disclosure.

[0158] Industrial availability

[0159] The technology disclosed herein can be widely used in various products equipped with electric motors, primarily in the fields of automotive electrical equipment and household electrical appliances.

[0160] Explanation of reference numerals in the attached figures

[0161] 1. Electric motor; 10. Stator; 11. Magnet; 20. Rotor; 21. Rotating shaft; 21a. First end; 21b. Second end; 22. Coil; 23. Molded resin; 30. Commutator; 31. Commutator segment; 40. Brush; 40a. Front end face; 40b. Rear end face; 41. Braided wire; 50, 50A, 50B, 50C. Brush spring; 50a. First bend; 50b. Second bend; 50c. Third bend; 51. Spiral section; 52, 52B. Lead wire; 52a. First section; 52 a1, Bending plate; 52b, Second part; 52c, Third part; 60, 60A, 60B, 60C, 60D, 60E, Brush holder; 60a, Brush storage part; 60b, First groove; 60c, Second groove; 61, 61A, 61B, 61C, First support part; 62, 62D, Second support part; 63, Third support part; 64, 63a, Protrusion; 65, Fourth support part; 70, Cover plate; 80, Power terminal; 91, First bearing; 92, Second bearing; 101, First bracket; 102, Second bracket.

Claims

1. An electric motor, wherein, This electric motor has the following features: A rotor having a rotating shaft extending along the axial direction; A commutator, which is mounted on the rotating shaft; The brush is in contact with the commutator; A brush spring for pressing the brush against the commutator; as well as A retainer that holds the brush spring. The brush spring is a constant load spring with a spiral section, which is formed by winding a strip of wire. The constant load spring applies pressure to the brush by means of the spiral portion that contacts the rear end face of the brush. The retainer has a first support portion that supports the scroll portion when it moves toward the rotating axis due to brush wear. When the volute portion abuts against the first support portion, the spring load generated by the brush spring becomes zero.

2. The electric motor according to claim 1, wherein, The moment when the spring load generated by the brush spring becomes zero due to the contact between the vortex portion and the first support portion is midway through the period after the period when the spring load of the brush spring is constant, and midway through the period when the spring load of the brush spring is not constant.

3. The electric motor according to claim 1, wherein, The zero spring load includes a state in which the brush spring has a pressing force on the brush, but the brush does not move in the direction of the rotation axis.

4. The electric motor according to any one of claims 1 to 3, wherein, The constant load spring has a lead wire that extends from the spiral section. The retainer has a second support portion that supports a portion of the lead wire.

5. The electric motor according to claim 4, wherein, The lead wire is bent at the first bend. The second support portion supports the lead wire by locking the first portion, which is located on the top side of the lead wire compared to the first bend portion.

6. The electric motor according to claim 5, wherein, The lead wire is bent at the first bend with the first portion facing the rotation axis.

7. The electric motor according to claim 5, wherein, The lead wire is bent at the first bend in such a way that the first portion is oriented toward the side opposite to the rotation axis.

8. The electric motor according to claim 5, wherein, The retainer has a first groove for insertion of the first part.

9. The electric motor according to claim 8, wherein, A curved piece is formed at the top of the first part. The curved piece is embedded in the first groove.

10. The electric motor according to claim 8, wherein, When the length of the first part of the brush spring before it is assembled to the retainer is set to L, and the length of the first groove is set to W, then W < L.

11. The electric motor according to claim 5, wherein, The lead wire is further bent at the second bend, located closer to the spiral section than the first bend. The retainer also has a third support portion that partially supports the lead wire. The third support portion supports the portion between the first bend and the second bend of the lead wire, which is the second portion.

12. The electric motor according to claim 11, wherein, The third support portion has a support surface that contacts the surface of the second support portion.

13. The electric motor according to claim 12, wherein, The retainer has a second groove for insertion of the second portion. The second groove has a pair of opposing inner surfaces. The supporting surface is one of the pair of inner surfaces.

14. The electric motor according to claim 13, wherein, The other inner side of the pair of inner sides is provided with a protrusion that protrudes toward the lead wire inserted into the second slot.

15. The electric motor according to claim 11, wherein, When the angle between the first part and the second part is set as α in the brush spring before it is assembled into the retainer, and the angle between the first part and the second part is set as β after the brush spring is assembled into the retainer, the relationship α≤β≤90° is satisfied.

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