Brush contact structure and motor

Abstract

To provide a brush contact structure in which a start failure of a motor due to an abrasion of a brush is suppressed.SOLUTION: A brush contact structure comprises: a commutator 34 to be provided to a rotator of a motor; a brush 40 to be contacted to the commutator 34; a brush holder 50 that movably holds the brush 40; and a pressure part 60 that presses a rear end part 42 of the brush 40 that is held by the brush holder 50 to make a sliding surface 41a to be formed to a tip end part 41 of the brush 40 to be contacted to the commutator 34. The brush 40, the brush holder 50, and the pressure part 60, are provided so as to a pair of them at a position that is opposite in a flat surface orthogonal to a rotational center shaft OA of the commutator 34 with the rotational center shaft OA as a center. A center shaft OS that is parallel to a movement direction of each brush 40 is separated in parallel each other to a shaft line OA1 orthogonal to the rotational center shaft OA of the commutator 34. The sliding surface 41a of each brush 40 is inclined to the flat surface orthogonal to the center shaft OS of each brush 40.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a brush contact structure and a motor provided with this brush contact structure.

Background Art

[0002] In a DC motor with brushes, the brushes that supply current to the commutator are movably held in brush holders. The brushes held in the brush holders are pressed against the commutator by a pressing member such as a spring so that the contact between the sliding surface at the tip and the commutator is maintained. As a result, as the sliding surface of the brush wears, the brush is pushed out toward the commutator side, so that the contact between the brush and the commutator is maintained (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] A gap is provided between the brush and the brush holder to smoothly move the brush within the brush holder. Therefore, when the commutator rotates, the brush comes into contact with the commutator in an inclined state within the brush holder. When the commutator always rotates in the same direction, only one R surface is formed on the sliding surface of the worn brush, so the wear powder of the burned brush does not deposit on the sliding surface. However, when the rotation direction of the motor is repeatedly reversed (forward rotation / reverse rotation), the direction in which the brush in the brush holder inclines changes according to the rotation direction of the commutator. As a result, two R surfaces are formed on the sliding surface of the worn brush. Since the wear powder of the burned brush deposits at the center of the two R surfaces, when the commutator stops at that part, during energization for starting, the energization from the brush to the commutator is blocked by the deposited wear powder, and the motor may have a poor start. In the brush contact structure of the prior art, the two R surfaces formed on the sliding surface of the brush and the deposition of the wear powder of the brush will be described later.

[0005] An object of the present invention is to provide a brush contact structure and a motor that suppress poor starting of the motor due to brush wear.

Means for Solving the Problems

[0006] One aspect of the present invention includes a commutator provided on a rotor of a motor, a brush that contacts the commutator, a brush holder that movably holds the brush, and a pressing portion that presses the rear end portion of the brush held by the brush holder to bring the sliding surface formed at the tip portion of the brush into contact with the commutator. The brush, the brush holder, and the pressing portion are provided in pairs at positions facing each other around the rotation center axis in a plane orthogonal to the rotation center axis of the commutator. The central axes parallel to the moving direction of each brush are separated from each other in parallel with respect to the axis orthogonal to the rotation center axis of the commutator, and the sliding surfaces of the respective brushes are inclined with respect to the planes orthogonal to the central axes of the respective brushes, which is a brush contact structure. Another aspect of the present invention is a motor including the above brush contact structure.

Advantages of the Invention

[0007] According to the brush contact structure and the motor of the present invention, it is possible to provide a brush contact structure and a motor that suppress the malfunction of the motor caused by the wear of the brush.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7A

Figure 7B

Figure 8

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the brush contact structure and the motor according to the present invention will be described with reference to the drawings. The drawings attached to this specification are all schematic diagrams, and in consideration of ease of understanding, etc., the shape, scale, aspect ratio in the vertical and horizontal directions, etc. of each part are changed or exaggerated from the actual object. Also, in the drawings, hatching indicating the cross section of members is appropriately omitted.

[0010] In this specification and the like, with respect to terms specifying shape, geometric conditions, and the degree thereof, such as terms like "parallel", "orthogonal", "direction", etc., in addition to the strict meaning of the term, a range that can be regarded as approximately parallel, approximately orthogonal, etc., and a range that can be generally regarded as that direction are included.

[0011] In this specification and the like, a direction parallel to the rotation center axis OA of the motor 1 shown in FIG. 1 is defined as the X direction (hereinafter, also referred to as the "axial direction X"). In the axial direction X, one side is the X1 direction and the other side is the X2 direction. The two directions orthogonal to the X direction are the Y (Y1 - Y2) direction and the Z (Z1 - Z2) direction. The Y direction is a direction (vertical direction / radial direction) that intersects the axial direction X perpendicularly. The Z direction is a direction (horizontal direction / radial direction) that intersects the axial direction horizontally. In this specification and the like, the "~ direction" is also appropriately referred to as the "~ side".

[0012] First, the overall configuration of the motor 1 having the brush contact structure of the embodiment will be described. FIG. 1 is a cross-sectional view showing the overall configuration of the motor 1 of the embodiment. FIG. 1 is a cross-sectional view of the X - Y plane obtained by cutting the motor 1 along the rotation center axis OA. In FIG. 1, for the sake of easy understanding of the configuration of the brush 40 and the brush holder 50, the illustration of the pressing portion 60 (described later) is omitted.

[0013] FIG. 2 is a conceptual diagram for explaining the brush contact structure of the embodiment. FIG. 2 is a conceptual diagram when viewing the commutator 34, the brush 40, and the brush holder 50 constituting the brush contact structure of the embodiment from the X2 side to the X1 side. FIG. 3A is a cross-sectional view showing the first configuration of the pressing portion 60. FIG. 3B is a cross-sectional view showing the second configuration of the pressing portion 60. FIGS. 3A and 3B respectively correspond to the cross-sectional views taken along the s1 - s1 line in FIG. 1.

[0014] The motor 1 of the embodiment is configured as a DC motor with brushes. As shown in FIG. 1, the motor 1 includes a frame 10, a stator 20, a rotor 30, brushes 40, a brush holder 50, a pressing portion 60 (see FIGS. 3A / 3B), etc. Among these, the commutator 34, the brushes 40, the brush holder 50, and the pressing portion 60 constitute a brush contact structure in this embodiment.

[0015] The frame 10 is an exterior member of the motor 1 and includes a frame body 11, a bracket 12, bearings 13, a bearing case 14, an input terminal 15, etc. The frame body 11 is a substantially cylindrical housing that holds the stator 20 on the inner peripheral side. A bracket 12 is provided at the end of the frame body 11 on the X1 side. The bracket 12 is a member that closes the opening on the X1 side of the frame body 11 and holds the bearing 13 on the X1 side. A bearing case 14 is provided at the end of the frame body 11 on the X2 side. The bearing case 14 is a member that holds the bearing 13 on the X2 side. The frame body 11 holds the rotor 30 via two bearings 13 provided at both ends in the axial direction X. The input terminal 15 is a terminal for supplying current to the brushes 40 (described later) and is connected to an external drive circuit (not shown).

[0016] The stator 20 is a member that forms a magnetic field for rotating the rotor 30 and is constituted by, for example, permanent magnets having S poles and N poles. The permanent magnets as the stator 20 are arranged at equal intervals on the inner peripheral surface of the frame body 11 so that the S poles and the N poles do not contact each other.

[0017] The rotor 30 is a component that rotates about the rotation center axis OA due to the magnetic interaction with the magnetic field formed by the stator 20. The rotor 30 is disposed on the inner circumferential side of the stator 20. The rotor 30 includes a rotating shaft 31, a core 32, a coil 33, a commutator 34, etc. The rotating shaft 31 is inserted so as to penetrate the rotation center axis OA of the rotor 30 and is fixed to the rotor 30. Bearings 13 are respectively fitted to both ends of the rotating shaft 31 in the X direction. The bearing 13 is a component that rotatably supports the rotating shaft 31 and is held by the bracket 12 and the bearing case 14. That is, the rotating shaft 31 can rotate about the rotation center axis OA by being supported by the bracket 12 and the bearing case 14 via the bearing 13.

[0018] The core 32 is a member (iron core) around which the coil 33 is wound and is fixed to the rotating shaft 31. The coil 33 is a wire-shaped member wound around the core 32 and is composed of, for example, a copper wire. The commutator 34 is an electrode electrically connected to the coil 33 and is provided along the outer circumference of the rotating shaft 31. The commutator 34 is divided into three parts by grooves 34a (see FIGS. 3A / 3B) provided along the outer circumference. The divided commutators are electrically insulated from each other.

[0019] In the embodiment, an example in which the commutator 34 is divided into three parts will be described, but the number of divisions of the commutator 34 is not limited to this. The sliding surface 41a (described later) formed at the tip 41 of the brush 40 contacts the commutator 34. When current is supplied from the brush 40 in contact with the commutator 34 to the commutator 34, current flows through the coil 33 wound around the core 32 of the rotor 30. Thereby, the rotor 30 (core 32) generates a rotational force due to the magnetic interaction with the magnetic field formed by the stator 20.

[0020] The brush 40 is a conductive member that supplies current to the commutator 34. The brush 40 is, for example, a carbon brush formed in the shape of an elongated square prism. The brush holder 50 is a frame that movably holds the brush 40. The brush holder 50 of the embodiment is integrally formed with the bracket 12. Note that the brush holder 50 is not limited to being integrally formed with the bracket 12. The brush holder 50 may be a separate component and may be attached to the bracket 12 by, for example, press-fitting, caulking, screwing, or the like.

[0021] As shown in FIG. 2, a pair of the brush 40 and the brush holder 50 are provided at positions facing each other about the rotation center axis OA in a plane (Y-Z plane) orthogonal to the rotation center axis OA of the commutator 34. More specifically, the pair of brushes 40, brush holders 50 (and the pressing portion 60 described later) are provided at point-symmetrical positions about the rotation center axis OA. Also, as shown in FIG. 1, the central axis OS (hereinafter also referred to as the "central axis OS of the brush 40") parallel to the moving direction Y of the brush 40 is orthogonal to the rotation center axis OA of the commutator 34. In FIG. 1, the central axis OS of the brush 40 and the line s1-s1 indicating the cross-sectional position in FIGS. 3A and 3B (described later) are shown as the same line.

[0022] As shown in FIG. 2, the central axis OS of each brush 40 is separated from the axis OA1 (hereinafter also referred to as the "axis OA1 of the commutator 34") orthogonal to the rotation center axis OA of the commutator 34 by a distance g1 in parallel. That is, each brush holder 50 is arranged such that the central axes OS of the respective brushes 40 are separated from the axis OA1 of the commutator 34 at equal intervals (interval g1). The distance g1 by which the central axis OS of the brush 40 is separated from the axis OA1 of the commutator 34 is, for example, 0.2 to 0.4 mm. Note that the numerical value of the interval g1 described here is an example and is not limited thereto. Also, in FIG. 2, an example is shown in which the direction of the axis OA1 is parallel to the vertical direction Y, but the direction of the axis OA1 may be parallel to the horizontal direction Z, for example.

[0023] A gap g2 is provided between the outer peripheral surface of the brush 40 and the inner peripheral surface of the brush holder 50. The gap g2 is provided to smoothly move the brush 40 within the brush holder 50. The gap g2 is provided between each outer peripheral surface (4 surfaces) of the brush 40 formed in the shape of an elongated quadrangular prism and each inner peripheral surface (4 surfaces) of the brush holder 50 facing each outer peripheral surface of the brush 40. The dimension of the gap g2 at each position is, for example, 0.05 to 0.15 mm. Note that, as shown in FIGS. 3A / 3B, the brush 40 is used in an inclined state inside the brush holder 50, but each of the above-described parts is designed to have the positional relationship shown in FIG. 2 with respect to the commutator 34.

[0024] Also, as shown in FIG. 2, the sliding surface 41a of each brush 40 is inclined with respect to a plane P (X-Z plane) orthogonal to the central axis OS of each brush 40. The angle θ by which the sliding surface 41a of the brush 40 is inclined with respect to the plane P is, for example, 6 to 10 degrees. The pair of brushes 40 and the brush holders 50 are provided at point-symmetrical positions about the rotation center axis OA. Therefore, the angle θ by which the sliding surface 41a of each of the pair of brushes 40 is inclined with respect to the plane P is the same. Also, the sliding surface 41a of each brush 40 is a flat surface and is inclined so that the flat surfaces are parallel to each other about the rotation center axis OA of the commutator 34. Note that the numerical value of the angle θ described here is an example and is not limited thereto.

[0025] Next, the first configuration and the second configuration of the pressing portion 60 will be described with reference to FIGS. 3A and 3B. Note that since the configuration of the pressing portion 60 is substantially the same on the Y1 side and the Y2 side, the configuration of the pressing portion 60 provided on the Y2 side will be described as an example.

[0026] First, the first configuration of the pressing portion 60 will be described. As shown in FIG. 3A, the pressing portion 60 of the first configuration is constituted by a torsion spring 61. The torsion spring 61 is a spring that generates a repulsive force around the rotation axis of the coil. The coil 61a of the torsion spring 61 is fitted into a support shaft 12a provided on the bracket 12 (hereinafter, the support shaft 12a will be described with the center of the coil 61a). The first arm 61b of the torsion spring 61 is fixed to a hook (not shown) provided on the bracket 12. Thereby, the counterclockwise rotation of the first arm 61b around the support shaft 12a is restricted.

[0027] On the other hand, the end of the second arm 61c of the torsion spring 61 is in contact with the rear end portion 42 of the brush 40. In the first configuration of the pressing portion 60, the brush holder 50 is provided with a groove portion 51 through which the second arm 61c of the torsion spring 61 passes. In the torsion spring 61, the coil 61a is twisted in the winding direction (counterclockwise) around the support shaft 12a. Therefore, a repulsive force (restoring force) is generated in the second arm 61c of the torsion spring 61 clockwise around the support shaft 12a. In the first configuration of the pressing portion 60, the rear end portion 42 of the brush 40 is pressed in the direction of the rotation center axis OA by the repulsive force generated in the second arm 61c of the torsion spring 61 and comes into contact with the commutator 34.

[0028] As described with reference to FIG. 2, the central axis OS of each brush 40 is spaced apart by a distance g1 parallel to the axis OA1 of the commutator 34. Further, the sliding surface 41a of each brush 40 is inclined with respect to the plane P (X-Z plane) orthogonal to the central axis OS of the brush 40. Therefore, as shown in FIGS. 3A and 3B described later, the brush 40 whose rear end portion 42 is pressed in the direction of the rotation center axis OA by the pressing portion 60 is inclined within the brush holder 50. The brush 40 is inclined such that the acute end 41b, which is an acute angle at the tip portion 41, contacts the adjacent inner peripheral surface of the brush holder 50, and the obtuse end 41c, which is an obtuse angle at the tip portion 41, is separated from the adjacent inner peripheral surface of the brush holder 50. Since the pair of brushes 40 have the same configuration, the directions in which the respective brushes 40 pressed by the pressing portion 60 are inclined are point-symmetric about the rotation center axis OA.

[0029] Next, the second configuration of the pressing portion 60 will be described. As shown in FIG. 3B, the pressing portion 60 of the second configuration is constituted by a coil spring 63. The coil spring 63 is a coil-shaped spring that generates a repulsive force in the extending direction. One end portion of the coil spring 63 abuts on the rear end portion 42 of the brush 40. The other end portion of the coil spring 63 abuts on the sealing plate 52. The sealing plate 52 is a member that closes the outer peripheral side in the radial direction Y in the brush holder 50. The coil spring 63 is housed in a compressed state between the rear end portion 42 of the brush 40 and the sealing plate 52. Therefore, a repulsive force (restoring force) is generated in the coil spring 63 in the direction of the rotation center axis OA. In the second configuration of the pressing portion 60, the rear end portion 42 of the brush 40 is pressed in the direction of the rotation center axis OA by the repulsive force of the coil spring 63 and comes into contact with the commutator 34.

[0030] Note that the configuration of the pressing portion 60 is not limited to the first and second configurations described above. The pressing portion 60 may have any configuration as long as it can press the rear end portion 42 of the brush 40 and bring the sliding surface 41a of the brush 40 into contact with the commutator 34.

[0031] Next, the brush contact structure of the present embodiment and the brush contact structure of the prior art will be compared to explain the differences in the effects of the respective brush contact structures. First, the brush contact structure of the prior art will be described. In the following description, parts that perform the same functions as the brush contact structure of the embodiment are appropriately assigned the same reference numerals or reference numerals with the same last two digits, and duplicate descriptions are appropriately omitted.

[0032] FIG. 4 is a conceptual diagram for explaining the brush contact structure of the prior art. FIG. 5A is a conceptual diagram showing the state of the brush 140 when the commutator 34 is rotated forward in the brush contact structure of the prior art. FIG. 5B is a conceptual diagram showing the state of the brush 140 when the commutator 34 is rotated backward in the brush contact structure of the prior art. FIG. 6 is a conceptual diagram showing the state in which the sliding surface of the brush 140 is worn in the brush contact structure of the prior art. Note that, in order to make it easier to understand the state in which the sliding surface of the brush 140 is worn, FIG. 6, like FIG. 4, shows a state in which the brush 140 is not inclined inside the brush holder 150.

[0033] In the following description, the counterclockwise rotation direction R1 of the commutator 34 about the rotation center axis OA is defined as "forward rotation", and the clockwise rotation direction R2 is defined as "reverse rotation". However, in the commutator 34, either rotation direction may be defined as "forward rotation" or "reverse rotation".

[0034] As shown in FIG. 4, in the brush contact structure of the prior art, the central axis OS of each brush 140 coincides with the axis OA1 of the commutator 34. Further, the sliding surface 141a of each brush 140 is a flat surface and is formed to be parallel to a plane P (X-Z plane) orthogonal to the central axis OS of the brush 140. Note that, in the brush contact structure of the prior art, the brush 140 is used in an inclined state inside the brush holder 150 as shown in FIG. 5A / FIG. 5B (described later), but each part described above is designed to have the positional relationship shown in FIG. 4 with respect to the commutator 34.

[0035] In the conventional brush contact structure, when the brush 40 is pressed toward the commutator 34 by the pressing portion 60, the direction in which the brush 140 tilts is different depending on the rotation direction of the commutator 34. Specifically, as shown in FIG. 5A, when the commutator 34 rotates forward, each brush 140 tilts in the direction opposite to the rotation direction R1 (clockwise) due to the frictional force generated between the sliding surface 41a and the commutator 34. Further, as shown in FIG. 5B, when the commutator 34 rotates reversely, each brush 140 tilts in the direction opposite to the rotation direction R2 (counterclockwise) due to the frictional force generated between the sliding surface 41a and the commutator 34.

[0036] As described above, in the conventional brush contact structure, the tilt direction of each brush 140 is reversed according to the rotation direction of the commutator 34. Therefore, when the rotation direction (forward rotation / reverse rotation) of the commutator 34 is repeatedly reversed, if the tip portion 141 of the brush 140 wears as the operating time elapses, as shown in FIG. 6, two R surfaces are formed on the sliding surface 141a of each brush 140. Wear powder of the burned brush accumulates at the center ct of the sliding surface 141a on which the two R surfaces are formed. Therefore, in a motor having the conventional brush contact structure, when the commutator 34 stops at that part, energization from the brush 140 to the commutator 34 may be interrupted by the accumulated wear powder during energization for starting, resulting in poor starting.

[0037] Next, the brush contact structure of the embodiment will be described. FIG. 7A is a conceptual diagram showing the state of the brush 40 when the commutator 34 is rotated forward in the brush contact structure of the embodiment. FIG. 7B is a conceptual diagram showing the state of the brush 40 when the commutator 34 is rotated reversely in the brush contact structure of the embodiment. FIG. 8 is a conceptual diagram showing the state in which the sliding surface of the brush 40 is worn in the brush contact structure of the embodiment.

[0038] In the brush contact structure of the embodiment, the central axis OS of each brush 40 is spaced apart by a distance g1 parallel to the axis OA1 of the commutator 34. Further, the sliding surface 41a of each brush 40 is inclined with respect to a plane P (X-Z plane) orthogonal to the central axis OS of the brush 40 (see FIG. 2). Therefore, when the brush 40 is pressed toward the commutator 34 by the pressing portion 60, as shown in FIG. 7A, the acute end 41b constituting the tip portion 41 of the brush 40 is inclined so as to contact the inner peripheral surface 50a on the tip side (commutator 34 side) of the brush holder 50.

[0039] As a result, in each brush 40, the substantially central portion of the sliding surface 41a contacts the commutator 34, the acute end 41b contacts the inner peripheral surface 50a on the tip side of the brush holder 50, and the corner portion 41d located on the diagonal line and on the opposite side to the acute end 41b contacts the inner peripheral surface 50a on the rear end side (pressing portion 60 side) of the brush holder 50. Therefore, each brush 40 is stably held at three points, i.e., the sliding surface 41a, the acute end 41b, and the corner portion 41d, with respect to the commutator 34 and the brush holder 50.

[0040] In the brush contact structure of the embodiment, since each brush 40 is stably held by the commutator 34 and the brush holder 50, as shown in FIG. 7A, when the commutator 34 rotates forward (rotation direction R1), and as shown in FIG. 7B, when the commutator 34 rotates backward (rotation direction R2), in either case, each brush 40 contacts the commutator 34 in the same inclination direction against the frictional force generated between the sliding surface 41a and the commutator 34, so that the inversion of the inclination direction does not occur.

[0041] Therefore, even when the rotation direction (forward rotation / reverse rotation) of the commutator 34 is repeatedly reversed and the tip 41 of the brush 40 wears over time, as shown in FIG. 8, only one R surface is formed on the sliding surface 41a of each brush 40. On the sliding surface 41a with only one R surface formed, the wear powder of the burned brush 40 is removed from the sliding surface 41a as the commutator 34 rotates, so it does not accumulate on the sliding surface 41a. Therefore, the problem of the energization from the brush 40 to the commutator 34 being blocked by the accumulated wear powder is less likely to occur. Thus, in the motor 1 having the brush contact structure of the embodiment, the wear powder of the burned brush 40 does not accumulate on the sliding surface 41a, and the problem of the energization from the brush 40 to the commutator 34 being blocked is less likely to occur, so it is possible to suppress the start-up failure due to the wear of the brush 40. Such an effect can be expected not only when the rotation direction of the commutator 34 is repeatedly reversed but also when the commutator 34 rotates in only one direction. Further, according to the brush contact structure of the embodiment, in addition to the above effect, effects such as further extending the life of the motor, reducing noise, and reducing electrical noise can be expected.

[0042] In the brush contact structure of the embodiment, the central axis OS of each brush 40 is spaced apart from the axis OA1 of the commutator 34 at equal intervals (interval g1). Therefore, each brush 40 can be brought into contact with the commutator 34 with a more uniform pressing force.

[0043] In the brush contact structure of the embodiment, the central axis OS of each brush 40 is spaced apart from the axis OA1 of the commutator 34, for example, at an interval of 0.2 to 0.4 mm. Therefore, each brush 40 can be brought into contact with the commutator 34 with a more appropriate pressing force.

[0044] In the brush contact structure of the embodiment, the sliding surface 41a of each brush 40 is a flat surface, and the flat surfaces are inclined so as to be parallel to each other around the rotation center axis OA of the commutator 34. Therefore, the wear amount of each brush 40 can be made more uniform.

[0045] In the brush contact structure of the embodiment, the sliding surface 41a of each brush 40 is inclined at an angle θ of, for example, 6 to 10 degrees with respect to a plane P (X-Z plane) orthogonal to the central axis OS of each brush 40. Therefore, each brush 40 can be brought into contact with the commutator 34 more stably.

[0046] As described above, one embodiment of the brush contact structure and the motor according to the present invention has been described. However, the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within the scope capable of achieving the object of the present invention are included in the present invention.

[0047] In the embodiment, the motor 1 having the structure shown in FIG. 1 has been described as a DC motor with brushes to which the brush contact structure and the motor according to the present invention are applied, but the present invention is not limited to this. The structure of the motor 1 shown in FIG. 1 is an example, and the motor may have any structure as long as the brush contact structure of the embodiment can be applied.

[0048] In the embodiment, an example in which the central axes OS of the respective brushes 40 are separated from each other at equal intervals (interval g1) with respect to the axis OA1 of the commutator 34 has been described, but the present invention is not limited to this. The central axes OS of the respective brushes 40 may be separated from the axis OA1 of the commutator 34 at different intervals.

[0049] In the embodiment, an example in which the sliding surfaces 41a of the respective brushes 40 are inclined such that the flat surfaces are parallel to each other about the rotation center axis OA of the commutator 34 has been described, but the present invention is not limited to this. The sliding surfaces 41a of the respective brushes 40 may be inclined such that the flat surfaces are non-parallel about the rotation center axis OA of the commutator 34.

[0050] In the embodiment, an example in which a pair of the brush 40 and the brush holder 50 are provided at positions facing each other about the rotation center axis OA has been described, but the present invention is not limited thereto. A plurality of pairs (for example, two pairs) of the brush 40 and the brush holder 50 may be provided at positions facing each other about the rotation center axis OA.

[0051] The above-described embodiments and modified forms can be used in appropriate combinations. However, since the configurations of the respective embodiments are apparent from the drawings and the description, detailed descriptions thereof are omitted. Furthermore, the brush contact structure and the motor according to the present invention are not limited to the embodiments described above.

Explanation of Reference Numerals

[0052] 1 Motor 30 Rotor 34 Commutator 40 Brush 41a Sliding Surface 50 Brush Holder 60 Pressing Portion

Claims

1. A commutator provided on a rotor of a motor, a brush that contacts the commutator, a brush holder that movably holds the brush, and a pressing portion that presses a rear end portion of the brush held by the brush holder to bring a sliding surface formed at a tip portion of the brush into contact with the commutator. The brush, the brush holder, and the pressing portion are provided in pairs at positions facing each other around the rotation center axis of the commutator in a plane orthogonal to the rotation center axis of the commutator. Center axes parallel to the moving direction of each brush are separated from each other in parallel with respect to an axis orthogonal to the rotation center axis of the commutator. The sliding surfaces of the respective brushes are inclined with respect to a plane orthogonal to the center axis of the respective brushes, a brush contact structure.

2. The center axes parallel to the moving direction of the respective brushes are separated from each other at equal intervals with respect to an axis orthogonal to the rotation center axis of the commutator. The brush contact structure according to claim 1.

3. The center axes parallel to the moving direction of the respective brushes are separated from each other at an interval of 0.2 to 0.4 mm with respect to an axis orthogonal to the rotation center axis of the commutator. The brush contact structure according to claim 2.

4. The sliding surfaces of the respective brushes are flat surfaces, and are inclined so that the flat surfaces are parallel to each other around the rotation center axis of the commutator. The brush contact structure according to claim 1.

5. The sliding surfaces of the respective brushes are inclined at an angle of 6 to 10 degrees with respect to a plane orthogonal to the center axis of the respective brushes. The brush contact structure according to claim 4.

6. A motor including the brush contact structure according to any one of claims 1 to 5.

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