Brushed motor
Patent Information
- Application Number
- JP2024545084
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2024-02-27
- Publication Date
- 2026-02-04
- Estimated Expiration
- 2044-02-27
AI Technical Summary
Motors with brushes often experience damage such as cracks at the bent portion of the brush due to high stress, leading to potential breakage.
A motor design that includes a brush with a depression or recess formed in the bent portion on at least one surface, increasing the density and strength of the bent area to prevent damage.
The motor effectively prevents or suppresses breakage at the bent portion of the brush, enhancing its durability and reliability.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a motor with a brush.
Background Art
[0002] A motor with a brush has a configuration in which a brush formed by sintering, for example, carbon powder is pressed against a commutator fixed to a rotating shaft by a biasing means. The brush is formed, for example, in a substantially U shape (including a substantially V shape and a substantially L shape. Hereinafter, referred to as a U shape or the like), one end side of the U shape or the like is supported, and the other end side of the U shape or the like is bent so as to contact the commutator (see, for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Thus, for example, a brush formed by being bent such as in a U shape is likely to have a large stress acting on the bent portion between the supported one end side and the other end side in contact with the commutator, and there is a tendency for damage such as cracks to occur at the bent portion.
[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a motor with a brush that can prevent or suppress damage at the bent portion of a bent brush.
Means for Solving the Problems
[0006] The present invention provides a motor with a brush, comprising a commutator fixed to a rotating shaft, a brush having one end pivotally supported and the other end in contact with the commutator and having a bent portion between the one end and the other end, and a depression for increasing the density of the bent portion is formed in a range of the bent portion on at least one of front and back surfaces of the brush.
Advantages of the Invention
[0007] The motor with a brush according to the present invention can prevent or suppress breakage at the bent portion of the brush formed by bending.
Brief Description of the Drawings
[0008]
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6A
Figure 6B
Embodiments for Carrying Out the Invention
[0009] Embodiments of the motor with a brush according to the present invention will be described as follows with reference to the drawings.
[0010] FIG. 1 is a sectional view showing a longitudinal section including the center of the rotating shaft 40 of the brush motor 100, FIG. 2 is a perspective view of the brush 80 of the brush motor 100 shown in FIG. 1 as viewed from the cap 20 side (in the direction of arrow A in FIG. 1), and FIG. 3 is a perspective view showing the brush 80 supported by the cap 20. However, FIG. 3 shows only one supported brush 80 and omits the description of the other brush 80. The brush motor 100 is a brushless coreless motor which is an embodiment of the brush motor according to the present invention.
[0011] The brush motor 100 (hereinafter simply referred to as the motor 100) includes, as shown in FIG. 1, a housing 10, a cap 20, a magnet 30, a rotating shaft 40, a coil 50, a commutator 60, and a brush 80.
[0012] One end face of the cylindrical tube portion 11 extending parallel to the axis C1 of the housing 10 is closed by an end wall 12. The other open end face of the tube portion 11 is closed by mounting a substantially disk-shaped cap 20. The cap 20 not only serves to close the other open end face of the tube portion 11 but also serves as a brush base for supporting the brush 80. That is, the cap 20 is an example of a brush base for supporting the brush 80. Further, a sleeve portion 13 extending parallel to the axis C1 is formed inside the housing 10. A cylindrical magnet 30 is fixed to the outer peripheral surface of the sleeve portion 13.
[0013] The rotating shaft 40 has a shaft portion 41 extending along the axis C1, a flange portion 42 having a larger diameter than the shaft portion 41, and a boss portion 43 protruding along the axis C1 on the side opposite to the shaft portion 41 with respect to the flange portion 42. The shaft portion 41 of the rotating shaft 40 is inserted inside the sleeve portion 13.
[0014] The rotating shaft 40 is rotatably supported about the axis C1 by a bearing 14 provided on the end wall 12 and a bearing 15 provided on the sleeve portion 13. One end of the rotating shaft 40 on the side supported by the bearing 14 projects outward from the bearing 14, while one end on the bearing 15 side is disposed inside the housing 10.
[0015] The coil 50 is formed in a cylindrical shape extending parallel to the shaft portion 41 around the shaft portion 41, and is disposed away from the magnet 30 and the cylindrical portion 11 in the space between the magnet 30 and the cylindrical portion 11 of the housing 10. The coil 50 is fixed to the outer periphery of the flange portion 42 of the rotating shaft 40 and rotates integrally with the rotating shaft 40.
[0016] The commutator 60 is fixed to the boss portion 43 and rotates integrally with the rotating shaft 40.
[0017] The brush 80 is, for example, a carbon brush formed by sintering. Two brushes 80 are provided, and the two brushes 80 are disposed opposite to each other with the commutator 60 interposed therebetween as shown in FIG. 2. The brush 80 is supported by a support pin 70 on the cap 20 as shown in FIG. 3. The brush 80 is formed in a substantially U shape in a plan view (a state seen in the directions of the axes C1 and C2) as shown in FIGS. 2 and 3.
[0018] Specifically, the brush 80 has one end side portion 81 including one end portion in the substantially U shape, the other end side portion 82 including the other end portion in the substantially U shape, and an intermediate portion 83 that connects the one end side portion 81 and the other end side portion 82. A bent portion 85, which is a bent portion in the substantially U shape, is formed in the intermediate portion 83.
[0019] FIG. 4 is a perspective view showing a spring groove 23 and a pin hole 24 formed in the support surface 21 of the cap 20, a torsion spring 90, and a support pin 70, and FIG. 5 is a perspective view showing details of the brush 80.
[0020] On one end side portion 81, as shown in FIGS. 3 and 5, a support shaft hole 84 (through hole) through which a support pin 70 is passed is formed. The end face 82a of the other end side portion 82 is a surface that contacts the circumferential surface of the commutator 60. The brush 80 is pivotally supported on the cap 20 by the support pin 70 passed through the support shaft hole 84, and is supported so as to be swingable (rotatable) around the axis C2 of the support pin 70.
[0021] The bent portion 85 is, for example, a portion that connects, at the outermost circumferential portion in the radial direction, a portion extending radially outward from the one end side portion 81 and a portion extending radially outward from the other end side portion 82 in the middle portion 83. The portion extending radially outward from the one end side portion 81 and the portion extending radially outward from the other end side portion 82 are, for example, portions that intersect at an acute angle.
[0022] The brush 80 is supported on the surface 21 (hereinafter referred to as the support surface 21) of the cap 20 facing the inside of the housing 10 in a state of being attached to the housing 10. As shown in FIG. 4, a spring groove 23 in which a torsion spring 90 described later is disposed and a pin hole 24 in which the support pin 70 is disposed are formed in the support surface 21.
[0023] As shown in FIG. 4, the support pin 70 has a fixed shaft portion 71 fitted into the pin hole 24 of the cap 20, a flange portion 73 that presses the winding portion 92 of a torsion spring 90 described later, and a support shaft portion 72 passed through the support shaft hole 84 of the brush 80. The fixed shaft portion 71, the flange portion 73, and the support shaft portion 72 are formed in a straight line along the axis C2 direction.
[0024] Here, as shown in FIG. 5, among the surfaces 86 and 87 of the brush 80 in a plan view (viewed along the axis C1 direction), a spring groove 89 in which a straight portion 95 of a torsion spring 90 described later is hooked is formed in the middle portion 83 of the surface 86 (the lower surface in FIG. 2 and the upper surface in FIG. 3; hereinafter referred to as the front (omote) surface 86) facing the flange portion 42 of the rotating shaft 40.
[0025] The torsion spring 90 is a spring member that applies a biasing force to press the end face 82a of the brush 80 against the peripheral surface of the commutator 60. As shown in FIG. 4, the torsion spring 90 has a straight portion 91 at one end, a straight portion 95 at the other end, and a spiral winding portion 92 formed between the straight portions 91 and 95, and generates a torque (biasing force) around the axis C2 of the winding portion 92 between the two straight portions 91 and 95.
[0026] Specifically, as shown in FIG. 4, the straight portion 91 and the winding portion 92 of the torsion spring 90 are arranged in a state of being inserted into the spring groove 23 of the cap 20. On the other hand, as shown in FIG. 3, the straight portion 95 of the torsion spring 90 is hooked on a spring groove 89 formed on the surface 86 of the brush 80. At this time, the rotation of one straight portion 91 around the axis C2 is blocked by the spring groove 23, and the other straight portion 95 is hooked on the spring groove 89 of the brush 80 in a state where the winding portion 92 is twisted in a direction in which the diameter becomes smaller than the natural state.
[0027] As a result, a torque in the direction of restoring to the natural state is generated in the winding portion 92, and this torque acts on the brush 80 through the straight portion 95 of the torsion spring 90, becoming a biasing force that presses the end face 82a of the other end side portion 82 of the brush 80 against the peripheral surface of the commutator 60.
[0028] The torsion spring 90 is arranged in a state where the straight portion 91 and the winding portion 92 are inserted into the spring groove 23 of the cap 20, and as shown in FIG. 3, the winding portion 92 is pressed from above against the flange portion 73 of the support pin 70 fixed to the pin hole 24.
[0029] Note that the torsion spring 90 of the present embodiment is formed with a radially extending portion 93 that extends radially outward and an axially extending portion 94 that extends in the direction of the axis C2 between the winding portion 92 and the straight portion 95 at the other end, and offsets the straight portion 95 from the back surface 87 to the surface 86 of the brush 80.
[0030] Further, on the surface 86 of the brush 80, in the range of the bent portion 85, there is formed a recess 88 having a substantially arc-shaped contour when viewed from above and a substantially U-shaped contour in a cross-section (longitudinal section) cut in the depth direction. The recess 88 is not formed over the entire width direction W from the inner peripheral edge to the outer peripheral edge of the bent portion 85 on the surface 86, but is formed only in a part of the width direction W.
[0031] In the brush 80 shown in FIG. 5, the recess 88 is formed at substantially the center in the width direction W of the bent portion 85. That is, the recess 88 is formed only in a range on the outer peripheral side of the inner peripheral edge of the bent portion 85 and on the inner peripheral side of the outer peripheral edge of the bent portion 85, and the portions on the outer peripheral side and the inner peripheral side of the recess 88 on the surface 86 are formed flat. Also, the central portion of the bottom surface of the recess 88 is formed flat.
[0032] However, the recess 88 is not limited to that shown in FIG. 5. For example, the recess 88 may be formed in the range from the inner peripheral edge to the outer peripheral edge of the bent portion 85 (including the inner peripheral edge and the outer peripheral edge) in the width direction W.
[0033] The recess 88 is formed by a convex portion provided on a mold for forming the surface 86 of the brush 80 in the sintering process of manufacturing the brush 80.
[0034] That is, the portions other than the recess 88 on the surface 86 of the brush 80 are formed flat, and the recess 88 is formed by the convex portion. Therefore, the convex portion of the mold has a longer dimension for pushing into the material of the brush 80 (for example, carbon powder) than the other portions (flat surfaces) other than the convex portion. Since the convex portion of the mold applies a strong pressure to the material of the brush 80 by the amount of the increased dimension, the density of the recess 88 of the brush 80 is higher than that of the portions other than the recess 88. As a result, the recess 88 of the brush 80 formed by sintering is formed with higher strength than the portions other than the recess 88.
[0035] Therefore, the motor 100 can prevent or suppress breakage at the bent portion 85 of the brush 80.
[0036] In the motor 100 of this embodiment, the spring groove 89 on which the straight portion 95 of the torsion spring 90 is hooked is formed to be recessed more than other portions of the surface 86, just like the recess 88. Therefore, the portion of the intermediate portion 83 where the spring groove 89 is formed is also formed with higher density and higher strength than other portions, similar to the bent portion 85 where the recess 88 is formed. And the recess 88 is connected to the spring groove 89, and the recess 88 and the spring groove 89 are integrally formed continuously.
[0037] For this reason, the range where the strength is increased by the recess 88 extends to the range where the strength is increased by the spring groove 89. Moreover, since the recess 88 and the spring groove 89 are continuous, the motor 100 can ensure the continuity of the portion where the strength of the brush 80 is increased. Also, since the recess 88 and the spring groove 89 are continuous, the motor 100 can discharge the sliding powder of the brush 80 accumulated inside the recess 88 to the outside of the recess 88 through the spring groove 89. That is, when the sliding powder of the brush 80 accumulates in the recess 88, the mechanical and electrical characteristics of the brush 80 may deteriorate, but the motor 100 can suppress these situations.
[0038] Note that in the motor 100, the recess 88 and the spring groove 89 are formed on the same surface 86, but the surface on which the recess 88 is formed and the surface on which the spring groove 89 is formed may be separate surfaces. Therefore, in the motor 100, the recess 88 may be formed on the surface 86 and the spring groove 89 may be formed on the back surface 87, or the recess 88 may be formed on the back surface 87 and the spring groove 89 may be formed on the surface 86.
[0039] In particular, in the case where the recess 88 is formed on the back surface 87 and the spring groove 89 is formed on the front surface 86 as in the latter case, the recess 88 faces the cap 20, making it difficult for the sliding powder of the brush 80 to reach the recess 88. Also, since the spring groove 89 is located on the side opposite to the cap 20, the straight portion 95 of the torsion spring 90 is more likely to be caught in the spring groove 89. Therefore, the motor 100 can suppress the accumulation of the sliding powder of the brush 80 in the recess 88 while suppressing the straight portion 95 of the torsion spring 90 from coming out of the spring groove 89.
[0040] Also, in this case, further, the flange portion 73 of the support pin 70 may cover at least a part (preferably all) of the recess 88 of the brush 80 from the back surface 87 side of the brush 80. Specifically, for example, by enlarging the entire outer diameter of the flange portion 73 or protruding a part of the flange portion 73, the flange portion 73 may cover at least a part of the recess 88. When configured in this way, the motor 100 can more effectively suppress the accumulation of the sliding powder of the brush 80 in the recess 88.
[0041] However, when the brush 80 is formed by sintering, it is preferable that the recess 88 and the spring groove 89 are formed on the same surface because it facilitates mold manufacturing.
[0042] Also, the motor 100 may not have the spring groove 89 on the front surface 86 or the back surface 87 of the brush 80. That is, the motor 100 only needs to be provided with a portion for hooking one end portion (corresponding to the straight portion 95) of the torsion spring 90 on the brush 80, and it is not necessary that the portion for hooking the torsion spring 90 is the front surface 86 or the back surface 87 of the brush 80. Therefore, for the motor 100, the portion for hooking the torsion spring 90 may be formed on the side surface of the brush 80.
[0043] Also, the recess 88 may be formed on both the front surface 86 and the back surface 87 of the brush 80 in the motor 100. That is, in the motor 100, the recess 88 only needs to be formed on at least one of the front surface 86 and the back surface 87 of the brush 80.
[0044] Also, the recess 88 in the motor 100 is not limited in terms of any dimension of its width, length, and depth.
[0045] (Modification example) FIG. 6A is a perspective view showing a brush 180 in which a support shaft hole 84 extending along the axis C2 is formed by connecting two holes 84a and 84b with different inner diameters along the direction of the axis C2, and a support pin 170 in which two shaft portions 75 and 74 with different outer diameters are connected along the direction of the axis C2. FIG. 6B is a plan view of the surface 86 of the brush 180 viewed from the front.
[0046] The brush 180 shown in FIG. 6A is a modification example of the brush 80 in the motor 100, and the illustrated support pin 170 is a modification example of the support pin 70 in the motor 100. And a motor in which the brush 80 in the motor 100 is replaced with the brush 180 and the support pin 70 is replaced with the support pin 170 is a modification example of the motor 100.
[0047] Similar to the brush 80, the brush 180 has a recess 88 formed in the bent portion 85 on the surface 86. Also, as shown in FIGS. 6A and 6B, the support shaft hole 84 formed in the one - end side portion 81 of the brush 180 is a stepped hole formed by connecting two holes 84a and 84b with different inner diameters (a large - diameter hole 84a with a relatively large inner diameter and a small - diameter hole 84b with a relatively small inner diameter) along the direction of the axis C2. Also, the support pin 170 is a stepped pin formed by connecting two shaft portions 75 and 74 with different outer diameters along the direction of the axis C2. And the large - diameter hole 84a, similar to the recess 88, has a higher density than the portion other than the large - diameter hole 84a. As a result, the large - diameter hole 84a formed by sintering has a higher strength than the portion other than the large - diameter hole 84a.
[0048] Here, the shaft portion 75 with an outer diameter larger than that of the shaft portion 74 can be passed through the large-diameter hole 84a with an inner diameter larger than that of the small-diameter hole 84b, but cannot be passed through the small-diameter hole 84b with a small inner diameter. The shaft portion 74 with an outer diameter smaller than that of the shaft portion 75 can be passed through the small-diameter hole 84b with a small inner diameter. And the brush 180 is swingable (rotatable) about the axis C2 by the support pin 170 when the shaft portion 75 is passed through the large-diameter hole 84a and the shaft portion 74 is passed through the small-diameter hole 84b.
[0049] And the motor of the modified example formed in this way also exhibits the same operations and effects as the motor 100 of the embodiment. Moreover, in the motor of the modified example, the support shaft hole 84 of the brush 180 is formed in a stepped manner, and the strength of the support shaft hole 84 is increased. Therefore, the motor of the modified example can prevent or suppress damage at the support shaft hole 84 of the brush. Also, in the motor of the modified example, the support shaft hole 84 of the brush 180 and the support pin 170 passed through the support shaft hole 84 are each formed in a stepped manner. Therefore, the motor of the modified example can prevent the brush 180 from coming off the support pin 170 when the support pin 170 is fixed to the cap 20.
[0050] In addition, in the motors of the above-described embodiment and modified example, although the spring groove 89 of the brush 80 and the hole 84a of the brush 180 have the function of increasing the density of the brush, they may not have the function of increasing the density of the brush. Also, in the motors of the above-described embodiment and modified example, the brushes 80 and 180 are formed by sintering, but the motor may be formed by a forming method other than sintering for the brushes 80 and 180. In that case as well, it is sufficient if a depression 88 for increasing the density of the bent portion 85 is formed within the range of the bent portion 85 of the brush 80.
Claims
1. a commutator fixed to the rotating shaft; a brush having one end supported by a shaft and the other end in contact with the commutator, the brush having a bent portion between the one end and the other end; a brush base having a support surface that supports the brush, The brush has depressions formed in the range of the bent portions on at least one of the front and back surfaces to increase the density of the bent portions, The recess is formed on one of the front and rear surfaces facing the support surface.
2. 2. The brushed motor according to claim 1, wherein the recess is not formed on one of the front and rear surfaces opposite to the surface facing the support surface.
3. a commutator fixed to the rotating shaft; a brush having one end supported by a shaft and the other end in contact with the commutator, the brush having a bent portion between the one end and the other end, The brush has depressions formed in the range of the bent portions on at least one of the front and back surfaces to increase the density of the bent portions, a spring member that presses the brush against the commutator; The brush has a groove formed on the surface where the recess is formed, for catching the spring member, The recess is connected to the groove.
4. a commutator fixed to the rotating shaft; a brush having one end supported by a shaft and the other end in contact with the commutator, the brush having a bent portion between the one end and the other end, The brush has depressions formed in the range of the bent portions on at least one of the front and back surfaces to increase the density of the bent portions, The brush has a through hole formed in the pivotally supported portion through which the support shaft passes, the through hole is formed with a step having a large diameter hole with a large inner diameter and a small diameter hole with a small inner diameter, A brushed motor, wherein the large diameter holes are holes that increase the density of the portions where the brushes are supported.