JP2008253026A - Electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the scattering of the abrasion powder of a brush to a bearing side while avoiding enlargement. <P>SOLUTION: This electric motor comprises: a commutator 50 fixed at a rotating shaft 30 having an output part at its one end; a brush holder 70 which holds the brush 60 sliding with the external peripheral face of the commutator 50, and has a penetration hole 71a into which the commutator 50 penetrates; and a bearing which is located between the brush holder 70 and one end of the rotating shaft 30, and supports the rotating shaft 30. A step 80 extending toward the circumferential direction is formed at least at a part of the internal peripheral face of the penetration hole 71a, and a receiving part 83 in which the step face of the step 80 receives the abrasion powder of the brush 60 is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric motor, for example, an electric motor suitable for use in a vehicle brake hydraulic pressure control device.

  Conventionally, as this type of electric motor, a commutator (commutator) fixed to a rotating shaft, an insertion hole through which the commutator is inserted, and a brush housing portion for housing a plurality of brushes that come into contact with the commutator And each brush is configured to be urged toward the commutator by a coil spring or the like provided in the brush accommodating portion and to come into contact with the commutator. Yes.

  By the way, the brush is made of a conductive material such as carbon or metal, and is worn by contact with the commutator to generate conductive wear powder. Such wear powder scatters due to factors such as the centrifugal force of the commutator and static electricity, and adheres to the inner peripheral surface of the insertion hole of the brush holder, or adheres to the bearing that supports the rotating shaft on the output side of the rotating shaft. . For this reason, there is a possibility that the insulation resistance between the brushes may be lowered when the amount of worn powder increases.

  Therefore, conventionally, a technique has been disclosed in which a groove extending in the axial direction of the rotating shaft is provided on the inner peripheral surface of the brush holder facing the commutator, and the wear powder adheres to the groove (for example, Patent Document 1). reference).

  In addition, in order to prevent scattered wear powder from adhering to the bearing side that supports the rotating shaft, conventionally, a shielding member is interposed between the commutator and the bearing, and the shielding member scatters to the bearing side. Techniques configured to block wear powder that is generated are disclosed (see, for example, Patent Documents 2 and 3).

JP-A-8-196059 JP 2000-516680 JP 2004-350457 A

  However, in the technique described in Patent Document 1, it is not possible to suppress the scattering of wear powder to the bearing side, and the conductive parts such as the bearing and the motor housing are electrically connected to the brush and the commutator. As a result, the insulation resistance may be reduced.

  In this regard, by adopting the techniques described in Patent Documents 2 and 3, it is possible to suppress the abrasion powder from scattering to the brush side, but a shielding member is interposed between the commutator and the bearing. Since it is necessary, it is necessary to set the length of the rotating shaft longer by the thickness of the shielding member. For this reason, there existed a problem that the whole electric motor enlarged in a rotating shaft direction.

  From such a point of view, the present invention is an electric motor that can suitably prevent a decrease in insulation resistance in the motor housing, and brush wear powder is scattered on the bearing side while avoiding an increase in size. It is an object of the present invention to provide an electric motor that can suppress the above.

  The present invention that solves such a problem holds a rotating shaft having an output portion at one end, a commutator fixed to the rotating shaft, and a brush that is in sliding contact with the outer peripheral surface of the commutator, and the commutator is inserted through the rotating shaft. A brush holder having an insertion hole, and a bearing that supports the rotation shaft between the brush holder and one end of the rotation shaft, and includes at least an inner peripheral surface of the insertion hole. A step portion extending in the circumferential direction is formed in a part, and the step surface of the step portion constitutes a receiving portion that receives the abrasion powder of the brush.

According to this electric motor, at least a part of the inner peripheral surface of the insertion hole has a stepped shape with a stepped portion extending in the circumferential direction, and the stepped surface of the stepped portion removes the abrasion powder of the brush. Since the receiving part is configured, wear powder is generated when the brush comes into contact with the commutator, and even if the wear powder scatters toward the bearing side, this is suitably received by the step receiving part (step surface). As a result, the wear powder is prevented from being scattered to the bearing side. As a result, it is possible to suitably prevent wear powder from adhering to conductive parts such as bearings and motor housings and increasing the amount.
Therefore, it is possible to prevent a problem that the insulation resistance is lowered due to electrical connection between the conductor parts such as the bearing and the motor housing and the brush and the commutator.

  In addition, since the receiving portion is located on the inner peripheral surface of the insertion hole of the brush holder, as in the conventional case, when the shielding member or the like is interposed between the commutator and the bearing, Therefore, it is not necessary to secure a space for the space between the brush holder and the bearing, and it is not necessary to set a long shaft length of the rotating shaft. Therefore, it is possible to prevent the entire electric motor from becoming large in the axial direction of the rotating shaft.

  Further, according to the present invention, the stepped portion is adjacent to the brush side of the small-diameter portion on the bearing side of the inner peripheral surface, and has a larger diameter than the small-diameter portion. It is preferable that the receiving portion is formed from a difference in diameter between the small diameter portion and the large diameter portion. According to this electric motor, by providing a small-diameter portion and a large-diameter portion adjacent to the small-diameter portion on the inner peripheral surface of the brush holder, the receiving portion can be obtained from the difference in diameter between the small-diameter portion and the large-diameter portion. Since the (step surface) is formed, an electric motor capable of suitably catching wear powder with a simple configuration is obtained.

  In the present invention, it is preferable that the receiving portion of the stepped portion is positioned closer to the bearing than a sliding contact portion between the commutator and the brush. According to this electric motor, since the receiving portion is located on the bearing side with respect to the sliding contact portion between the commutator and the brush, it is possible to effectively catch (catch) wear powder scattered to the bearing side, It is possible to suitably suppress the abrasion powder from scattering to the bearing side.

In the present invention, it is preferable that an inner wall portion extending from the large diameter portion toward the brush is provided in a part of the large diameter portion. According to this electric motor, the abrasion powder scattered toward the inner surface side of the brush holder can be received (captured) by the inner wall portion, and it is preferable to prevent the abrasion powder from adhering to the inner surface of the brush holder. be able to.
In addition, the inner wall part is provided in a part of the large-diameter part and does not surround all around the commutator, so even if wear powder adheres to the inner wall and increases, it surrounds all around the commutator. In this case, the abrasion powder does not adhere to the surface, and the insulation resistance between the brushes can be suitably maintained. Therefore, an electric motor that can maintain stable rotation for a long period of time can be obtained.

  In the present invention, it is preferable that the stepped portion is provided concentrically around the rotation axis. According to this electric motor, the clearance between the commutator and the stepped portion is kept constant, and the scattered abrasion powder can be effectively received (caught).

  According to the present invention, an electric motor that can suitably prevent a decrease in insulation resistance, and can prevent brush abrasion powder from scattering to the bearing side while avoiding an increase in size. Is obtained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. In the following embodiments, an electric motor used in a vehicle brake hydraulic pressure control device is illustrated, but the application of the electric motor according to the present invention is not limited.

  As shown in FIG. 1, the electric motor M according to the present embodiment is applied to a vehicle brake hydraulic pressure control device U and serves as a power source for a reciprocating pump P mounted on a base body 100. It is integrally fixed to one surface of 100.

  In addition to the electric motor M, the base 100 is attached with a reciprocating pump P, a normally open electromagnetic valve 101, a normally closed electromagnetic valve 102, a pressure sensor 103, a reservoir 104, a control housing 105, and the like. As shown in FIG. 2, the control housing 105 includes a control board 106 for controlling the electric motor M and the electromagnetic valves 101 and 102, a connection terminal 107 for supplying electric power to the electric motor M, and the electromagnetic valves 101 and 102. The electromagnetic coil 108 and the like for driving are accommodated.

  The electric motor M includes a motor housing 10, a stator 20, a rotating shaft 30, a rotor 40, a commutator (commutator) 50, a brush 60, a brush holder 70, a brush accommodating portion 73, a coil spring 73b, a stopper 74, and a pigtail 90 ( 3) and the like.

  The motor housing 10 includes a yoke 11 that is formed in a substantially bottomed cylindrical shape, and a cover 12 that covers the opening of the yoke 11. A ball bearing 11 b is fixed to the bottom of the yoke 11. A recess 12a is formed inside the cover 12, and a ball bearing 12b is fixed to the recess 12a. In the present embodiment, the ball bearing 12b corresponds to the “bearing” in the “claims”.

  The rotating shaft 30 is rotatably supported by the ball bearings 11b and 12b, and has an output portion on one end side (side supported by the ball bearing 12b). The rotating shaft 30 includes a main shaft portion 31, an eccentric shaft portion 32 protruding from the end surface of the main shaft portion 31, and a tip shaft portion 33 protruding from the end surface of the eccentric shaft portion 32. A ball bearing 32a that is in contact with a plunger (not shown) of the reciprocating pump P shown in FIG. 1 is fitted in the eccentric shaft portion 32 so that the plunger can reciprocate between the eccentric shaft portion 32 and the ball bearing 32a. The eccentric cam is configured. The tip shaft portion 33 is coaxially supported by the main shaft portion 31 and is rotatably supported by a ball bearing 33 a fixed to the mounting hole 110 of the base body 100. A seal member 111 is interposed between the base body 100 and the electric motor M.

  The rotor 40 includes a core 41 fitted into the main shaft portion 31 of the rotating shaft 30, an insulator 42 covering the core 41, and a magnet wire (armature winding) 43 wound around a slot formed in the core 41. It has. The rotor 40 is located on the inner peripheral side of the stator 20.

  The commutator 50 is fitted in the main shaft portion 31 between the rotor 40 and the ball bearing 12 b and rotates together with the main shaft portion 31. The commutator 50 is inserted into an insertion hole 71a, which will be described later, formed in the brush holder 70, and the brush 60 held by the brush holder 70 is in sliding contact with the outer peripheral surface thereof.

The brush 60 is movably accommodated in the brush accommodating portion 73 while being urged toward the commutator 50 by a coil spring 73b as a brush spring, and the tip surface of the brush 60 is energized by the urging force of the coil spring 73b. It comes in contact with the outer peripheral surface.
As shown in FIG. 4, a feeding pigtail 90 is connected to the brush 60 at the rear end of one surface thereof (the surface facing the circumferential direction of the yoke 11). The brush 60 is inserted into the brush accommodating portion 73 by inserting the pigtail 90 into the guide groove 73 d of the brush accommodating portion 73.
Such a brush 60 is made of a conductive material such as carbon or metal, and generates abrasion powder when it contacts the commutator 50.

  As shown in FIG. 2, the brush holder 70 includes a holder main body 70A disposed so as to surround the commutator 50, and a rod-like portion 70B protruding from the holder main body 70A. The holder main body 70A is connected to the cover 12 and the rotor 40. Is fixed by being fitted into the yoke 11.

  When the electric motor M is assembled to the base body 100, the rod-like part 70 </ b> B is inserted into the insertion hole 109 formed in the base body 100, and the tip portion protrudes toward the control housing 105 side. The rod-like portion 70B includes two power supply paths 78 made of a conductor (only one is shown in FIG. 2). The power supply path 78 is disposed over the entire length of the rod-shaped portion 70B, and the base end portion thereof is connected to a connection terminal 70c that protrudes from the holder main body 70A into the rod-shaped portion 70B. The tip of the power supply path 78 is connected to the connection terminal 107 of the control housing 105 when the electric motor M is assembled to the base body 100.

  As shown in FIG. 3A, the holder main body 70 </ b> A has an annular portion 71 having an insertion hole 71 a through which the commutator 50 (see FIG. 2) is inserted, and an outer peripheral edge of the annular portion 71 with a predetermined interval. The number of brush accommodating portions 73, 73,..., Arranged in a radial manner so as to surround the standing peripheral wall portion 72, the insertion hole 71a of the annular portion 71, and the same number as the brush accommodating portions 73. Terminals 75, 75,...

  In the annular portion 71, the peripheral portion of the portion where the brush accommodating portion 73 is disposed (the portion where the peripheral wall portion 72 is not erected) is notched in a concave shape, and each notched portion 71b of the notched portion 71b is cut. The insertion opening 73g on the rear end surface of the brush accommodating portion 73 is exposed in the space.

  The peripheral wall portion 72 is formed on the inner surface of the annular portion 71 (the surface facing the rotor 40 shown in FIG. 2), and is fixed to the peripheral wall portion 11a of the yoke 11 (see FIG. 2).

  The brush housing 73 holds the brush 60 in a slidable manner, and is formed on the inner surface side of the annular portion 71 in this embodiment. The brush accommodating portion 73 has a square cylindrical shape (see FIGS. 3A and 4), and has a front end face facing the insertion hole 71a (a surface on the side of the commutator 50, see FIG. 2) to open the brush 60. The insertion opening 73g is opened in the rear end face (the surface on the peripheral wall 11a side of the yoke 11, see FIG. 2) facing the space of the notch 71b, and the brush 60 is urged toward the commutator 50 side. The coil spring 73b to be inserted can be inserted. A guide groove 73 d (see FIG. 4) for inserting the pigtail 90 connected to the rear end portion of the brush 60 is formed on one side surface (surface facing the circumferential direction of the yoke 11) of the brush housing portion 73. It is formed along the sliding direction. The guide groove 73d is provided on the same side surface in all the brush accommodating portions 73.

  As shown in FIGS. 3A and 4, the stopper 74 is locked to the rear end surface of the brush accommodating portion 73 (the surface on the peripheral wall portion 11 a side of the yoke 11, see FIG. 2) and is formed on the rear end surface. Further, the insertion opening 73g (see FIG. 3A) is closed, and the brush 60 and the coil spring 73b inserted into the brush accommodating portion 73 are prevented from being detached.

As shown in FIGS. 3B and 4, the insertion hole 71 a is formed with a stepped portion 80 extending in the circumferential direction on a part of the inner peripheral surface, and the stepped surface formed by the stepped portion 80. The receiving part 83 which receives the abrasion powder of the brush 60 is comprised by 81a and the internal peripheral surface 82a adjacent to this. In the present embodiment, the step portion 80 includes a small diameter portion 81 and a large diameter portion 82 having a larger diameter than the small diameter portion 81.
As shown in FIG. 5, the small-diameter portion 81 is provided on the ball bearing 12 b side of the inner peripheral surface of the insertion hole 71 a and is formed so as to be close to the outer peripheral surface on one end side of the commutator 50. The surface facing the brush 60 side of the small diameter portion 81 is a surface orthogonal to the axis of the rotating shaft 30, and forms a step surface 81 a with the adjacent large diameter portion 82.

The large-diameter portion 82 is provided adjacent to the brush 60 side of the small-diameter portion 81, has a larger diameter than the small-diameter portion 81, and is formed to be separated from the outer peripheral surface of the commutator 50. The inner peripheral surface 82a of the large diameter portion 82 is a surface parallel to the axis of the rotating shaft 30, and is a surface orthogonal to the adjacent inner peripheral surface 82a.
That is, the receiving portion 83 includes a step surface 81a (small diameter portion 81) orthogonal to the axis of the rotating shaft 30 and an inner peripheral surface 82a (large diameter portion) continuous to the step surface 81a and parallel to the axis of the rotating shaft 30. 82), and as shown in FIG. 5, the cross-sectional shape is substantially L-shaped. Accordingly, a concave space is formed around the commutator 50 by the receiving portion 83. In this embodiment, as shown to Fig.3 (a), the receiving part 83 is formed in three places between the brush accommodating parts 73 in the insertion hole 71a, and each receiving part 83 is the circumferential direction of the insertion hole 71a. It is set as the structure which does not continue to.

  Further, as shown in FIG. 5, the receiving portion 83 is provided so as to be positioned closer to the ball bearing 12 b than the sliding contact portion between the commutator 50 and the brush 60. That is, the receiving portion 83 is positioned between the sliding contact portion and the ball bearing 12b and receives (captures) the wear powder of the brush 60 as will be described later.

  A part of the large diameter portion 82 is provided with an inner wall portion 84 extending from the large diameter portion 82 toward the brush 60 as shown in FIGS. As shown in FIG. 5, the inner wall portion 84 has an inner surface that is continuous with an inner peripheral surface 82a constituting the receiving portion 83 of the stepped portion 80, and as shown in FIG. 3B, one end portion 84a. The side is connected to the side surface of the brush accommodating portion 73 adjacent thereto and closed, and the other end portion 84b side is provided so as to have a gap with the brush accommodating portion 73 adjacent thereto. Therefore, the inner wall portion 84 does not continue in the circumferential direction of the large-diameter portion 82, and the space of the insertion hole 71a and the space on the inner surface side of the annular portion 71 through the gap S provided on the side of the other end portion 84b. Has come to communicate.

  Further, as shown in FIG. 5, a concave portion 76 is formed in the annular portion 71 of the holder main body 70A on the side facing the ball bearing 12b. The recess 76 serves to expand the volume between the holder main body 70A and the cover 12, and even if the wear powder scatters toward the cover 12, the scattered wear powder moves to the holder main body 70A. It becomes easy to get caught and it is suppressed that it adheres to the ball bearing 12b side.

Next, as shown in FIGS. 3A and 4, the terminal 75 is exposed at the inner surface side of the annular portion 71 and is disposed at a portion close to the brush housing portion 73. The end of the pigtail 90 is connected to each terminal 75 via a connection terminal 91.
A part of the terminal 75 penetrates from the inner surface side to the outer surface side of the holder main body 70A via a terminal (not shown), and is connected to a connection terminal 70c provided on the outer surface side, and is connected to the power feeding path 78 of the rod-shaped portion 70B. Has been.

  One end of the pigtail 90 is connected to the side of the rear end of the brush 60 as described above, and the other end is connected to the terminal 75 via the connection terminal 91. The pigtail 90 is formed by weaving a plurality of conductive wires, and has enough flexibility to follow the movement of the brush 60. The inner wall portion 84 of the large-diameter portion 82 also serves to prevent the pigtail 90 that has moved to the tip side of the brush 60 as the brush 60 wears from being exposed into the insertion hole 71a.

Next, as shown in FIG. 6, a procedure for mounting the holder main body 70A (70) on the yoke 11 will be described.
(1) Prior to mounting the holder main body 70A, first, the rotor 40 and the commutator 50 are press-fitted into the rotating shaft 30 and assembled.
(2) The brush 60, the coil spring 73b, and the stopper 74 are assembled to the brush holder 70, and the brush holder 70 is inserted into the rotating shaft 30.
(3) From above, the cover 12 into which the ball bearing 12b is press-fitted is press-fitted into the rotary shaft 30 and assembled.
(4) Press-fit the bearing 32 a into the eccentric shaft portion 32.
(5) Finally, the parts assembled in the above (1) to (4) are press-fitted and assembled to the yoke 11 to which the ball bearing 11b and the stator 20 are fixed in advance.
By this press-fitting, the peripheral wall portion 72 of the holder main body 70 </ b> A comes into contact with and is fixed to the peripheral wall portion 11 a of the yoke 11. The peripheral wall 72 is fixed at a predetermined position by a protrusion 13 (see FIG. 5) that protrudes from the peripheral wall 11a of the yoke 11.

  Thus, when the holder main body 70A is attached to the opening of the yoke 11, the commutator 50 is partially accommodated in the insertion hole 71a of the holder main body 70A as shown in FIG. The receiving portion 83 of the stepped portion 80 is positioned between the sliding contact portion with the ball bearing 12b and the ball bearing 12b.

Therefore, even if the brush 60 is brought into contact with the commutator 50 due to the use of the electric motor M, wear powder is generated, and even if the wear powder scatters toward the ball bearing 12b, it is received by the receiving portion 83 (step difference) of the step portion 80. The surface 81a and the inner peripheral surface 82a) are suitably received (captured), and the scattering of wear powder toward the ball bearing 12b is suppressed.
When the brush 60 is worn by use, the connecting portion of the pigtail 90 moves to the commutator 50 side along the guide groove 73d by the biasing force of the coil spring 73b, and the brush 60 is in good contact with the commutator 50. Is maintained.

According to the electric motor M according to the present embodiment configured as described above, the stepped portion 80 extending in the circumferential direction is formed on at least a part of the inner peripheral surface of the insertion hole 71a. Since the step surface 81a and the inner peripheral surface 82a constitute the receiving portion 83 that receives the abrasion powder of the brush 60, the abrasion powder is generated when the brush 60 comes into contact with the commutator 50, and the abrasion powder is directed toward the ball bearing 12b. Even if it is scattered, this is suitably received (captured) by the receiving portion 83 of the stepped portion 80, and the abrasion powder is prevented from scattering to the ball bearing 12b side. As a result, it is possible to suitably prevent the wear powder from adhering to the conductive parts such as the ball bearing 12b and the cover 12 and increasing it.
Therefore, it is possible to prevent a problem that the insulation resistance is lowered due to electrical connection between the conductive parts such as the ball bearing 12b and the cover 12 and the brush 60 and the commutator 50.

  Further, since the stepped portion 80 is provided on the inner peripheral surface of the insertion hole 71a of the holder main body 70A, the stepped portion 80 is provided as in the conventional case, such as when a shielding member is interposed between the commutator and the bearing. Therefore, it is not necessary to secure a space for this, and it is not necessary to set the axial length of the rotating shaft 30 to be long. Therefore, it is possible to prevent the entire electric motor M from becoming large in the axial direction of the rotary shaft 30.

  Further, the step portion 80 is constituted by a small diameter portion 81 and a large diameter portion 82, and the receiving portion 83 is formed from a difference in diameter between the small diameter portion 81 and the large diameter portion 82. An electric motor M that can suitably receive (capture) wear powder with a simple configuration of forming the portion 82 is obtained.

  Further, since the receiving portion 83 is positioned closer to the ball bearing 12b than the slidable contact portion between the commutator 50 and the brush 60, the wear powder scattered toward the ball bearing 12b is effectively received (captured). Therefore, it is possible to suitably suppress the scattering of wear powder toward the ball bearing 12b.

In addition, since the inner wall portion 84 extending from the large diameter portion 82 toward the brush 60 is provided in a part of the large diameter portion 82, wear powder scattered in the radial direction of the brush holder 70 is removed from the inner wall portion 84. Can be received (captured), and it is possible to suitably prevent the wear powder from adhering to the inner surface side of the holder main body 70A.
Further, since the inner wall portion 84 is provided in a part of the large diameter portion 82 and does not surround the entire commutator 50, even if wear powder adheres to the inner wall portion 84 and increases, The situation where the abrasion powder adheres so as to surround all the surroundings can be maintained, and the insulation resistance between the brushes 60 can be suitably maintained. Therefore, an electric motor M that can maintain a stable rotation over a long period of time is obtained.

  Further, since the stepped portion 80 is provided concentrically around the rotating shaft 30, the clearance between the commutator 50 and the stepped portion 80 is kept constant, and the scattered wear powder is effectively received (captured). be able to.

In the above-described embodiment, the step surface 81 a of the step portion 80 is configured as a surface orthogonal to the axis of the rotating shaft 30, and the inner peripheral surface 82 a of the step portion 80 is a surface parallel to the axis of the rotating shaft 30. However, the present invention is not limited to these, and each surface may be provided at a desired angle, or each surface may be a curved surface instead of a flat surface.
Further, the step portion 80 is constituted by the small diameter portion 81 and the large diameter portion 82, but the medium diameter portion that is larger in diameter than the small diameter portion 81 and smaller in diameter than the large diameter portion 82, has a small diameter portion 81 and a large diameter. It may be further formed between the portion 82 and formed into a multistage shape.
Furthermore, although the step portion 80 is provided at three locations in the circumferential direction of the insertion hole 71a, the step portion 80 may be provided on the entire circumference of the insertion hole 71a.

1 is an exploded perspective view showing a vehicle brake hydraulic pressure control device in which an electric motor according to an embodiment of the present invention is used. 1 is an exploded side sectional view showing a vehicle brake hydraulic pressure control device in which an electric motor according to an embodiment of the present invention is used. (A) is a figure which shows the inner surface of a brush holder, (b) is an enlarged explanatory view of a step part. It is the partially-omission perspective view which looked at the brush holder from the inner surface side. It is the schematic cross section which showed the step part. It is explanatory drawing at the time of an assembly | attachment.

Explanation of symbols

M Electric motor 10 Motor housing 12b Ball bearing
DESCRIPTION OF SYMBOLS 30 Rotating shaft 31 Main shaft part 41 Laminated core 42 Insulator 43 Magnet wire 50 Commutator 60 Brush 70 Brush holder 70A Holder main body 73 Brush accommodation part 80 Step part 81 Small diameter part 81a Step surface 82 Large diameter part 82a Inner peripheral surface 83 Receiving part 84 Inner wall U Vehicle brake fluid pressure control device

Claims (5)

A rotating shaft having an output at one end;
A commutator fixed to the rotating shaft;
A brush holder that holds a brush that is in sliding contact with the outer peripheral surface of the commutator and has an insertion hole through which the commutator is inserted;
An electric motor comprising a bearing between the brush holder and one end of the rotating shaft and supporting the rotating shaft;
A step portion extending in the circumferential direction is formed on at least a part of the inner peripheral surface of the insertion hole, and the step surface of the step portion constitutes a receiving portion that receives the abrasion powder of the brush. Electric motor. The step portion has a small diameter portion adjacent to the commutator on the bearing side on the inner peripheral surface, a large diameter adjacent to the brush side of the small diameter portion, and having a larger diameter than the small diameter portion and separated from the commutator. It consists of a diameter part,
The electric motor according to claim 1, wherein the receiving portion is formed from a difference in diameter between the small diameter portion and the large diameter portion.   The electric motor according to claim 1, wherein the receiving portion is located on the bearing side with respect to a sliding contact portion between the commutator and the brush.   The electric motor according to claim 2, wherein an inner wall portion extending from the large diameter portion toward the brush is provided in a part of the large diameter portion.   The electric motor according to any one of claims 1 to 4, wherein the stepped portion is provided concentrically around the rotation shaft.

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