Brush retaining device and electric motor

Abstract

To provide a brush retaining device capable of suppressing operation noise.SOLUTION: According to an embodiment, a brush retaining device includes a retaining part and a pressing mechanism. The retaining part retains a brush for supplying power to a commutator. The pressing mechanism presses the brush against a circumferential surface of the commutator. The front-end portion of the retaining part faces the commutator. The retaining part has elastic gripping parts for sandwiching the brush on the front-end portion side.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present invention relates to a brush retainer and an electric motor. [Background technology]

[0002] A brush holder is provided in an electric motor including brushes. It is desirable to suppress operating noise in the electric motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6323916 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE DISCLOSURE An embodiment of the present invention provides a brush retainer that can reduce operating noise. [Means for solving the problem]

[0005] According to an embodiment, a brush holding device includes a holding portion and a pressing mechanism. The holding portion holds a brush that supplies power to a commutator. The pressing mechanism presses the brush against a peripheral surface of the commutator. A tip portion of the holding portion faces the commutator. The holding portion has an elastic gripping portion on the tip portion side that clamps the brush. Effect of the Invention

[0006] According to an embodiment of the present invention, a brush holder capable of suppressing operating noise can be provided. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a top view illustrating a brush holding device according to the first embodiment. [Diagram 2] FIG. 2 is a view seen from the direction of arrow A in FIG. [Diagram 3] FIG. 3 is a perspective view illustrating a part of the brush holding device according to the first embodiment. [Figure 4] 4(a) and 4(b) are schematic views illustrating a holding portion of the brush holding device according to the first embodiment. [Diagram 5] FIG. 5 is a diagram illustrating a part of the brush holding device according to the first embodiment. [Figure 6] FIG. 6 is a perspective view illustrating a part of the brush holding device according to the second embodiment. [Figure 7] 7(a) and 7(b) are schematic views illustrating a holding portion of a brush holding device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

[0009] (First embodiment) Fig. 1 is a top view showing an example of a brush holding device 1. Fig. 2 is a view seen from the direction of arrow A in Fig. 1. The brush holding device 1 holds, for example, brushes 30. The brushes 30 supply power to a commutator 2 (for example, a commutator) used in an electric motor. The commutator 2 has, for example, a cylindrical shape.

[0010] 1, the brush holding device 1 includes, for example, an annular portion 10, a holding portion 20, and a pressing mechanism 40. The annular portion 10 and the holding portion 20 hold a brush 30.

[0011] The annular portion 10 may be, for example, disk-shaped. The annular portion 10 includes a hole 10a. The hole 10a is circular. The commutator 2 can be inserted into the hole 10a. The inner diameter of the hole 10a is larger than the outer diameter of the commutator 2. For example, when the brush holding device 1 is provided on the electric motor, the center position of the commutator 2 and the center position C1 of the annular portion 10 are the same center position.

[0012] In the embodiment, the thickness direction of the annular portion 10 is defined as a height direction Z. The direction rotating around the center position C1 is defined as a circumferential direction ω. The direction passing through the center position C1 and perpendicular to the height direction Z is defined as an axial direction L.

[0013] The annular portion 10 is provided with two holding portions 20. The two holding portions 20 are fixed to the annular portion 10. The two holding portions 20 may be opposed to each other across a center position C1. The two holding portions 20 may have, for example, the same configuration as each other. The annular portion 10 holds, for example, a lower surface 30d of the brush 30.

[0014] FIG. 3 is a perspective view showing an example of the appearance of a portion of the brush holding device 1. As shown in FIG. As shown in FIG. 3, in the brush holding device 1, a holding portion 20 and a pressing mechanism 40 are provided on the first surface 10b of the annular portion 10.

[0015] The brush 30 may have, for example, a substantially rectangular parallelepiped shape (including a cubic shape). The holding portion 20 holds the brush 30. The holding portion 20 includes, for example, a first side portion 21, a second side portion 22, and an upper surface portion 23. The first side portion 21 holds the first side surface 30a of the brush 30. The second side portion 22 holds the second side surface 30b of the brush 30. The upper surface portion 23 holds the upper surface 30c of the brush 30. A rectangular parallelepiped-shaped space is formed by the first surface 10b of the annular portion 10, the first side portion 21, the second side portion 22, and the upper surface portion 23. The brush 30 is provided in this space. The tip surface of the brush 30 may have a shape that follows the peripheral surface of the commutator 2.

[0016] The tip portion 20a of the holding portion 20 faces the commutator 2. The first side portion 21 includes a first gripping portion 21a on the tip portion 20a side. The first gripping portion 21a has a cantilever structure. The second side portion 22 includes a second gripping portion 22a on the tip portion 20a side. The second gripping portion 22a has a cantilever structure. The distance in the circumferential direction ω between the first gripping portion 21a and the brush 30 becomes shorter toward the tip portion 20a side (commutator 2 side) of the holding portion 20. The distance in the circumferential direction ω between the second gripping portion 22a and the brush 30 becomes shorter toward the tip portion 20a side (commutator 2 side) of the holding portion 20. For example, the first gripping portion 21a moves toward the second gripping portion 22a side as it moves toward the tip portion 20a side. For example, the second gripping portion 22a moves toward the first gripping portion 21a as it advances toward the tip portion 20a. According to the embodiment, the brush 30 is clamped between the first gripping portion 21a and the second gripping portion 22a. The symbol F indicates the pressing force with which the first gripping portion 21a presses the brush 30. In Fig. 3, the pressing force with which the second gripping portion 22a presses the brush 30 is omitted from illustration.

[0017] For example, the holding portion 20 includes a slit that provides elasticity to the first gripping portion 21a. For example, a slit S11 is provided between the first gripping portion 21a and the first surface 10b of the annular portion 10. A slit S12 is provided between the first gripping portion 21a and the upper surface portion 23. This makes the first gripping portion 21a of the holding portion 20 elastic in the circumferential direction.

[0018] For example, the holding portion 20 includes a slit that provides elasticity to the second gripping portion 22a. For example, a slit S21 is provided between the second gripping portion 22a and the first surface 10b of the annular portion 10. A slit S22 is provided between the second gripping portion 22a and the upper surface portion 23. This makes the second gripping portion 22a of the holding portion 20 elastic in the circumferential direction.

[0019] 4(a) and 4(b) are schematic diagrams showing an example of the front view of the holding portion 20 as viewed from the tip portion 20a side. Fig. 4(a) is a schematic diagram showing a state in which the holding portion 20 does not hold the brush 30. Fig. 4(b) is a schematic diagram showing a state in which the holding portion 20 holds the brush 30.

[0020] Width W1 shown in Fig. 4(a) is the distance between first grip portion 21a and second grip portion 22a when brush 30 is not being held. Width W2 shown in Fig. 4(b) is the distance between first grip portion 21a and second grip portion 22a when brush 30 is being held. For example, width W2 is the width of brush 30. Width W2 is wider than width W1.

[0021] As shown in FIG. 4(a) and FIG. 4(b), when the holding portion 20 holds the brush 30, the first gripping portion 21a and the second gripping portion 22a spread apart by distances d1 and d2, respectively, and hold the sides of the brush 30. For example, the first gripping portion 21a includes a contact portion P1 that contacts the brush 30 in the circumferential direction ω. For example, at the contact portion P1, the clearance between the first gripping portion 21a and the brush 30 becomes zero. The second gripping portion 22a includes a contact portion P2 that contacts the brush 30 in the circumferential direction ω. For example, at the contact portion P2, the clearance between the second gripping portion 22a and the brush 30 becomes zero.

[0022] 3, the first side surface portion 21, the second side surface portion 22, and the top surface portion 23 may include cutout portions 21b, 22b, and 23b, respectively. The cutout portion 21b is aligned along the longitudinal direction of the first side surface portion 21, for example. The cutout portion 22b is aligned along the longitudinal direction of the second side surface portion 22, for example. The cutout portion 23b is aligned along the longitudinal direction of the top surface portion 23, for example. The second side surface portion 22 and the top surface portion 23 may not have cutout portions.

[0023] The pressing mechanism 40 presses the brush 30 held by the holding portion 20 against the circumferential surface of the commutator 2. The pressing mechanism 40 is, for example, a spring portion. The pressing mechanism 40 is provided on the first surface 10b of the annular portion 10. The pressing mechanism 40 includes a first protrusion 41, a second protrusion 42, and a spring 43. The first protrusion 41 and the second protrusion 42 are provided on the first surface 10b of the annular portion 10. The first protrusion 41 is located near the first side surface portion 21. The second protrusion 42 is located near the first protrusion 41. The spring 43 is wound around the first protrusion 41. One end of the wound spring 43 is engaged with the second protrusion 42. The wound spring 43 passes through the cutout portion 21b of the first side surface portion 21. The other end of the passed spring 43 is located on the rear end surface of the brush 30. The other end located on this rear end surface forms a push-in portion 43a.

[0024] The brush 30 held in the holding portion 20 is pressed toward the commutator 2 by the pressing portion 43a of the pressing mechanism 40. The tip surface of the brush 30 fits along the circumferential surface of the commutator 2. This brings the circumferential surface of the commutator 2 and the tip surface of the brush 30 into close contact with each other.

[0025] As the commutator 2 rotates in the circumferential direction ω, the brush 30 in close contact with the commutator 2 is also displaced in the circumferential direction ω. At this time, the displacement of the brush 30 in the circumferential direction ω is restricted by the first gripping portion 21a and the second gripping portion 22a. The first gripping portion 21a and the second gripping portion 22a are in close contact with the side surfaces of the brush 30, respectively, and have elasticity. For example, the first gripping portion 21a, the second gripping portion 22a, and the brush 30 are integrated. Therefore, when the commutator 2 rotates in the circumferential direction ω, it is possible to prevent the first gripping portion 21a and the brush 30 from colliding with each other. For example, it is possible to prevent the second gripping portion 22a and the brush 30 from coming into contact with each other.

[0026] As described above, for example, the brush holding device 1 can significantly suppress the contact noise between the brush 30 and the holding portion 20. For example, the brush holding device 1 can prevent the generation of contact noise.

[0027] In the above example, contact noise caused by contact at the tip portions of the two side surfaces of the brush 30 (first grip portion 21a and second grip portion 22a) is suppressed. In the embodiment, the contact noise may be suppressed at least on one of the two side surfaces of the brush 30. In this case as well, a reduction effect after contact can be obtained. For example, at least one of the first grip portion 21a and the second grip portion 22a may have the above configuration.

[0028] Generally, a clearance exists between the outer surface of the brush and the inner surface of the holder so that no sliding resistance occurs in the direction in which the brush is pressed against the holder. When the electric motor rotates, the brush moves a distance equal to the clearance as the electric motor rotates, causing the brush and the brush holder to come into contact with each other, generating contact noise.

[0029] As a means for reducing the contact noise, for example, a reference example in which the clearance is made small to the extent possible in manufacturing can be considered. For example, a reference example in which the direction of the holding portion is tilted from the axial direction to limit the displacement of the brush can be considered. In these reference examples, the clearance does not become zero. In these reference examples, it is difficult to sufficiently suppress the contact noise.

[0030] In the embodiment, for example, contact noise can be significantly suppressed. According to the embodiment, for example, the generation of contact noise can be prevented. According to the embodiment, it is possible to provide a brush holding device capable of suppressing contact noise.

[0031] In the embodiment, for example, the slits provide elasticity to the first gripping portion 21a and the second gripping portion 22a. The number and shape of the slits can be modified in various ways. At least one of the first gripping portion 21a, the second gripping portion 22a, and the upper gripping portion 23a may have elasticity. For example, three or more slits may be provided in each of the first gripping portion 21a and the second gripping portion 22a.

[0032] Fig. 5 is a diagram showing an example of a part of a brush holding device 1A which is a modified example of the brush holding device 1. Fig. 5 shows an example in which three slits are provided in the first gripping portion 21a and the second gripping portion 22a. As shown in Fig. 5, the first gripping portion 21a of the brush holding device 1A is provided with a slit S13 in addition to the slits S11 and S12. The second gripping portion 22a is provided with a slit S23 in addition to the slits S21 and S22. By providing the slit S13 between the slits S11 and S12 and the slit S23 between the slits S21 and S22, the elastic forces of the first gripping portion 21a and the second gripping portion 22a can be weakened. This makes it possible to control the elastic forces of the first gripping portion 21a and the second gripping portion 22a.

[0033] Second embodiment In the second embodiment, the tip portion of the upper surface portion has elasticity. In the second embodiment, the configuration described in relation to the first embodiment may be applied within a technically possible range.

[0034] FIG. 6 is a perspective view showing an example of the external appearance of a portion of the brush holding device 1B. As shown in FIG. 6, the upper gripping portion 23a is provided on the tip portion 20a side of the upper surface portion 23. The upper gripping portion 23a has a cantilever structure. The upper gripping portion 23a descends toward the first surface 10b as it approaches the tip. For example, as the upper gripping portion 23a advances toward the tip side, the distance between the upper gripping portion 23a and the first surface 10b of the annular portion 10 becomes shorter. According to the embodiment, the brush 30 is clamped by the first surface 10b and the upper gripping portion 23a. The symbol F indicates the pressing force with which the upper gripping portion 23a presses the brush 30.

[0035] The holding portion 20 includes slits that provide elasticity to the upper gripping portion 23a. For example, a slit S31 is provided between the upper gripping portion 23a and the first side surface portion 21. A slit S32 is provided between the upper gripping portion 23a and the second side surface portion 22. This makes the upper gripping portion 23a of the holding portion 20 elastic at least in the height direction Z.

[0036] 7(a) and 7(b) are schematic diagrams showing an example of the front view of the holding portion 20 as viewed from the tip portion 20a side. Fig. 7(a) is a schematic diagram showing a state in which the holding portion 20 does not hold the brush 30. Fig. 7(b) is a schematic diagram showing a state in which the holding portion 20 holds the brush 30.

[0037] Height H1 shown in Fig. 7(a) is the height between upper gripping portion 23a and first surface 10b of annular portion 10 when brush 30 is not being held. Height H2 (>height H1) shown in Fig. 7(b) is the height between upper gripping portion 23a and first surface 10b of annular portion 10 when brush 30 is being held. Height H2 when brush 30 is being held is higher than height H1 when brush 30 is not being held.

[0038] 7(a) and 7(b), when the holding portion 20 holds the brush 30, the upper gripping portion 23a is raised by a distance d3, and the upper gripping portion 23a holds the upper surface 30c of the brush 30. For example, the upper gripping portion 23a includes a contact portion P3 that contacts the brush 30 in the height direction Z. In other words, at the contact portion P3, the clearance between the upper gripping portion 23a and the brush 30 becomes zero.

[0039] As the commutator 2 rotates in the circumferential direction, the brush 30 in close contact with the commutator 2 is also displaced in the circumferential direction ω. At this time, the upper gripping portion 23a and the upper surface of the brush 30 are in close contact with each other, so the circumferential displacement of the brush 30 is restricted. This makes it possible to prevent the first gripping portion 21a and the brush 30 from colliding with each other. For example, it is possible to prevent the second gripping portion 22a and the brush 30 from coming into contact with each other.

[0040] In the brush holding device 1B according to the embodiment, the contact noise between the brush 30 and the holding portion 20 can be suppressed.

[0041] In the brush holding device 1B, in addition to the upper gripping portion 23a described in relation to the second embodiment, the first gripping portion 21a and the second gripping portion 22a described in relation to the first embodiment may be provided.

[0042] Third embodiment In the third embodiment, for example, the sliding resistance is adjusted at the contact portions of the side surfaces and the upper and lower surfaces of the brush 30. By the adjustment, for example, the displacement of the brush 30 along the axial direction L caused by the pressing mechanism 40 is suppressed.

[0043] In the third embodiment, the frictional force is adjusted to adjust the sliding resistance. The adjustment forces include a frictional force R1 generated between the first gripping portion 21a and the brush 30, and a frictional force R2 generated between the second gripping portion 22a and the brush 30. The pressing force F with which the gripping portions 21a and 22a press the brush 30 in the circumferential direction ω, and the frictional forces R (R1, R2) can be set as follows.

[0044] The pressing force (elastic force) F is, F = k x where k is the spring constant, and x is, for example, the distance that the first gripping portion 21a and the second gripping portion 22a move in the circumferential direction ω when the brush 30 is pressed against them (for example, d1 and d2 in FIG. 4).

[0045] The friction force R is R = μ × F R = μ × k × x μ is the friction coefficient μ1 between the first gripping portion 21a and the brush 30, or the friction coefficient μ2 between the second gripping portion 22a and the brush 30.

[0046] The friction force R can be adjusted by changing the spring constant k and the friction coefficient μ. For example, the spring constant k can be changed by the following various configurations. For example, the thickness of the first gripping portion 21a and the second gripping portion 22a may be changed. For example, a smaller thickness results in a smaller spring constant k. A larger thickness results in a larger spring constant k. For example, the height of the first gripping portion 21a and the second gripping portion 22a may be changed. For example, the length of the slits S11, S12, S21, and S22 in the height direction may be changed. If the height of the slits is low, the spring constant k becomes small. If the height of the slits is high, the spring constant k becomes large. For example, the material of the retaining portion 20 may be changed. Changing the material can change the elastic modulus. A higher elastic modulus results in a higher spring constant k. A lower elastic modulus results in a lower spring constant k. For example, the interference dimension may be changed in a state in which the brush 30 is held by the holding portion 20. When the interference dimension is small, the spring constant k is small. When the interference dimension is large, the spring constant k is large.

[0047] The friction coefficient μ can be changed, for example, by the following various methods. For example, the material composition of the brush 30 may be changed. For example, if the ratio of the sliding material in the brush 30 is high, the friction coefficient μ becomes low. For example, if the ratio of the sliding material in the brush 30 is low, the friction coefficient μ becomes high. For example, the material of the brush holder 1 may be changed. For example, if the sliding grade of the brush holder 1 is high, the friction coefficient μ becomes low. For example, if the sliding grade of the brush holder 1 is low, the friction coefficient μ becomes high. For example, a lubricant (grease) may be provided at contact portions P1 and P2 between the holding portion 20 and the brush 30. The lubricant may be, for example, conductive.

[0048] In the brush holding device 1 of the third embodiment, the sliding resistance of the brush 30 held by the holding portion 20 may be determined by the elastic force of the gripping portion of the holding portion 20 and the frictional force between the tip portion and the brush 30. The elastic force of the gripping portion includes, for example, the elastic force of the first gripping portion 21a. The elastic force of the tip portion includes, for example, the elastic force of the second gripping portion 22a. The frictional force between the gripping portion and the brush 30 includes, for example, the frictional force between the first gripping portion 21a and the brush 30. The frictional force between the gripping portion and the brush 30 includes, for example, the frictional force between the second gripping portion 22a and the brush 30. This makes it possible to appropriately control the sliding resistance of the brush 30 held by the holding portion 20.

[0049] Regarding the brush holding device 1A according to the second embodiment, the sliding resistance between the upper gripping portion 23a and the brush 30 can be adjusted by using the configuration described in the third embodiment.

[0050] According to the embodiment, a brush holding device capable of suppressing operating noise can be provided.

[0051] The above describes the embodiment of the present invention with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configurations of the elements of the brush holder, such as the holding portion, the annular portion, and the pressing mechanism, are within the scope of the present invention as long as a person skilled in the art can implement the present invention in a similar manner and obtain similar effects by appropriately selecting from the known range.

[0052] Any combination of two or more elements of each embodiment, within the scope of technical feasibility, is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0053] In addition, all brush holding devices that can be implemented by a person skilled in the art by making appropriate design modifications based on the brush holding device described above as an embodiment of the present invention also fall within the scope of the present invention as long as they include the gist of the present invention.

[0054] In addition, within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and it will be understood that these modifications and alterations also fall within the scope of the present invention. [Explanation of symbols]

[0055] 1: Brush holder 1A: Brush holder 1B: Brush holder 2: Commutator 10: Ring section 10a: Hole 10b: 1st side 20: Holding part 20a:Tip part 21: 1st side part 21a: 1st gripping part 21b: Notch 22: 2nd side part 22a: Second gripping part 22b: Notch 23:Top part 23a: Top grip part 23b: Notch 30: Brush 40: Pressing mechanism 41: 1st protrusion 42:Second protrusion 43: Spring 43a: Push-in part C1: Center position F: Pressing force H1: Height H2: Height L: Axial direction P1: Contact part P2: Contact part P3: Contact part S11: Slit S12: Slit S13: Slit S21: Slit S22: Slit S23: Slit S31: Slit S32: Slit W1, W2: Width Z: Height direction d1: distance d2: distance d3: distance ω: Circumferential direction

Claims

1. a holding portion for holding a brush that supplies power to the commutator; a pressing mechanism for pressing the brush against a peripheral surface of the commutator; Equipped with A tip portion of the holding portion faces the commutator, A brush holding device, wherein the holding portion has an elastic gripping portion on the tip portion side that clamps the brush.

2. The brush holder of claim 1 , wherein the sliding resistance of the brush is determined based on an elastic force of the gripping portion and a frictional force between the gripping portion and the brush.

3. The brush retainer of claim 1 , wherein the retaining portion includes slits that render the gripping portion resilient.

4. Further comprising an annular portion; the annular portion includes a hole into which the commutator can be inserted and holds a lower surface of the brush; The brush is disposed on an upper surface of the annular portion; The brush is rectangular in shape, the retaining portion includes a first side portion, a second side portion, and a top portion; the first side portion holds a first side of the brush; the second side portion holds a second side of the brush; The upper surface portion supports an upper surface of the brush, The brush retainer of claim 1 , wherein the grip portion is included in at least one of the first side portion, the second side portion, and the top portion.

5. An electric motor comprising the brush holding device according to any one of claims 1 to 4.

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