JP6096417B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor provided with a brush device, and relates to an electric motor characterized by the brush device.

  In general, an electric motor including a brush device includes a motor yoke having a magnet provided on the inner periphery thereof, an armature that is rotatably disposed inside the motor yoke, and a brush device that supplies current to the armature. The armature includes a commutator having a plurality of commutator pieces to which coils are connected, and the brush device includes at least two brushes that are in sliding contact with the commutator pieces.

FIG. 12 shows a conventional example of a commutator and a brush device in the electric motor as described above. FIG. 12 is a partial cross-sectional view of the commutator and the brush device viewed from the axial direction of the armature shaft. The commutator 313 is fitted on the armature shaft 311 of the armature, and the brush device 320 is arranged so as to surround the commutator 313. Yes.

The commutator 313 includes a columnar commutator main body 313a into which the armature shaft 311 is inserted, and a plurality of commutator pieces 313b provided on the outer wall of the commutator main body 313a at equal pitches in the circumferential direction. The brush device 321 includes a substantially disc-shaped brush holder stay 321, a brush holder 324 attached to the brush holder stay 321, a brush 322 disposed in the brush holder 324, and a spring 325. Yes.

The brush 322 is held in the brush holder 324 so as to be linearly movable toward the commutator 313, and is biased toward the commutator piece 313 b of the commutator 313 by the spring 325, and the commutator piece 313 b in the biased state. Slid in contact. Here, the brush 322 includes a fixing portion 340 where the pigtail 323 is arranged and fixed, and a sliding contact portion 341 which is arranged at a position closer to the commutator 313 than the fixing portion 340 and slides on the commutator piece 313. . The pigtail 323 supplies current to the brush 322.

Here, in order to improve the performance of the electric motor, it is generally required to improve the rectification between the commutator 312 and the brush 322. As a technique for improving the rectification property, there is a technique for decreasing the inter-segment voltage between adjacent commutator pieces (313b, 313b) by increasing the number of segments of the commutator 313, that is, the number of the commutator pieces 313b. FIG. 12 shows a commutator 313 in which the number of commutator pieces 313b is set to “18” in order to reduce the voltage between segments. Here, even in the electric motor in which the number of the commutator pieces 313b is increased as described above, there is a demand for downsizing the motor body, and the outer diameter of the commutator 313 needs to be reduced due to the demand for downsizing. In this way, when the outer diameter of the commutator 313 is reduced, the arc length (a) of each commutator piece 313b is set short.

  Thus, when the arc length (a) of the commutator piece 313b is set short, the circumferential length (b) of the sliding contact portion 341 of the brush 322 is a certain length (for example, this arc length). When set to (a) the same length as (a), the “time for which the brush 322 short-circuits” between adjacent commutator pieces (313b, 313b) is close to the “time for which short-circuiting is not performed”. There is a problem in that the “time to end up” becomes relatively long.

In order to solve this problem, for example, in the electric motor shown in Patent Document 1, the shape of the slidable contact portion slidably contacting the commutator is set differently from the shape of the fixed portion where the pigtail is arranged and fixed on the brush. ing. More specifically, the area of the facing surface facing the commutator in the sliding contact portion of the brush is set to be smaller than the area of the facing surface of the fixed portion.

JP 2001-112218 A

  However, when the shapes of the opposing surfaces of the fixed portion and the sliding contact portion are different in the brush as described above, it is difficult to stably and reliably guide the brush toward the commutator.

Therefore, the present invention has been made in view of the above-described circumstances, and in the electric motor in which the shape of the facing surface of the fixed portion of the pigtail and the facing surface of the sliding contact portion are different from each other in the brush, the brush is used as a commutator. The present invention provides an electric motor that enables stable and reliable guidance.

In order to solve the above problems, an electric motor according to claim 1 includes a motor yoke having a magnet provided on the inner periphery thereof, and a commutator that is rotatably disposed inside the motor yoke and to which a coil is connected. And a brush device having a brush slidably in contact with the armature commutator. The brush device of the electric motor is formed in a substantially U-shaped cross section, and holds the brush so that it can move directly toward the commutator, a spring that biases the brush toward the commutator, and the brush holder And a brush holder stay formed of a resin that guides the brush toward the commutator together with the brush holder. In such an electric motor, the brush is arranged at a position closer to the commutator than the fixed portion where the pigtail is arranged and fixed, and the cross-sectional area of the facing surface facing the commutator is smaller than the fixed portion. A fixed sliding portion is guided toward the commutator by the brush holder, and the sliding contact portion is guided by sliding contact guide means formed integrally with the brush holder stay. The slidable contact guide means is formed of a pair of projecting portions that are erected in the brush holder stay in the axial direction and are disposed in the brush holder so as to face each other in the circumferential direction, and both outer walls of the pair of projecting portions are While abutting on the brush holder, both inner walls guide the sliding contact portion. The length in the circumferential direction of the fixed portion of the brush is formed larger than the interval between the inner walls of the pair of protrusions.

The electric motor of claim 2 is the electric motor according to claim 1, commutator is formed in a cylindrical shape, that the brush is linearly movable arranged radially with respect to the commutator Features.
According to a third aspect of the present invention, there is provided the electric motor according to the first aspect, wherein the commutator is formed in a disk shape, and the brush is disposed so as to be linearly movable in the axial direction with respect to the commutator. And

The electric motor of claim 4 is the electric motor according to claim 3, sliding portions guiding means, the brush holder stay by the shape and substantially the same shape of the opposing surfaces of the sliding contact portion of the brush The sliding contact portion is guided by the insertion hole.

According to the electric motor of the present invention, in the electric motor in which the shape of the facing surface of the fixed portion of the pigtail and the facing surface of the sliding contact portion are different in the brush, the brush can be stably and reliably guided toward the commutator. It becomes possible.

It is a front view of the electric motor with a reduction gear in the 1st Embodiment of this invention. It is a perspective view of the armature and brush apparatus with which the electric motor in the 1st Embodiment of this invention is equipped. It is a perspective view of the brush apparatus in the 1st Embodiment of this invention. It is a perspective view of the brush in the 1st Embodiment of this invention. FIG. 4 is a developed perspective view of a portion surrounded by a range A in FIG. 3. It is a front view of the brush apparatus in the 1st Embodiment of this invention. It is a front view of the brush apparatus in the 2nd Embodiment of this invention. It is a perspective view of the brush apparatus in the 3rd Embodiment of this invention. It is a perspective view of the brush apparatus seen from the viewpoint F in FIG. It is a perspective view of the brush in the 3rd Embodiment of this invention. FIG. 9 is a developed perspective view of a portion surrounded by a range G in FIG. 8. It is a partial sectional view of a commutator and a brush device in a conventional example.

  (First Embodiment) Next, a reduction gear-equipped electric motor according to a first embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a front view of the electric motor with a reduction gear according to the first embodiment of the present invention, and FIG. 2 is a perspective view of the armature and brush device provided in the electric motor according to the first embodiment of the present invention. is there.

  As shown in FIG. 1, the electric motor 1 with a speed reducer includes an electric motor 2 and a speed reducer 3 to which the electric motor 2 is attached and decelerates the rotational output of the electric motor 2. Here, the speed reducer 3 decelerates the rotation of the electric motor 2 and outputs a decelerated rotation, and a connector 4 to which a power supply coupler (not shown) that supplies current to the electric motor 4 is connected. .

  As shown in FIG. 1 and FIG. 2, the electric motor 2 includes a motor yoke 5 having four magnets 6 forming four magnetic poles provided on the inner peripheral surface, and an armature rotatably disposed inside the motor yoke. 10 and a brush device 20 that supplies current from the connector 4 to the armature 10.

  As shown in FIG. 2, the armature 10 includes an armature shaft 11 on which worms (11 a, 11 b) are formed, an armature core 12 that is externally fixed to the armature shaft 11, and a coil 14 that is wound around the armature core 12. And a commutator 13 which is externally fitted and fixed to the armature shaft 11 at a position close to the armature core 12. Here, the commutator 13 includes a columnar commutator main body 13a inserted and fixed to the armature shaft 11, and a plurality of commutator pieces 13b arranged on the outer wall of the commutator main body 13a at equal circumferential pitches. A coil 14 is electrically connected to 13b. As described above, the commutator 13 is formed in a cylinder shape, and in this embodiment, the number of the commutator pieces 13b is set to “18”.

  Next, the brush apparatus 20 of this Embodiment is demonstrated based on FIGS. 2-6. Here, FIG. 3 is a perspective view of the brush device according to the first embodiment of the present invention, and FIG. 4 is a perspective view of the brush according to the first embodiment of the present invention. 5 is a developed perspective view of a portion surrounded by a range A in FIG. 3, and FIG. 6 is a front view of the brush device according to the first embodiment of the present invention.

  As shown in FIG. 2, the brush device 20 is disposed so as to surround the commutator 13 of the armature 10. As shown in FIG. 3, the brush device 20 includes a substantially disc-shaped brush holder stay 21 formed of resin, brush holders (24a, 24b, 24c) attached to the brush holder stay 21, and brush holders (24a, 24a, 24b, 24c), and three springs (22a, 22b, 22c) that are held so as to move linearly toward the commutator 13 and springs that urge the brushes (22a, 22b, 22c) toward the commutator 13. 25a, 25b, 25c). Further, the brush device 20 is provided with a choke coil (28, 29) for noise countermeasures and a circuit breaker (C / B) 30 for countermeasures against fail-safety caused by heat.

  Here, the brush 22 includes a positive brush 22a, a negative brush 22b, and a high-speed brush 22c, and these brushes (22a, 22b, 22c) are arranged so as to be in sliding contact with the commutator piece 13b of the commutator 13. Yes. Further, the springs (25a, 25b, 25c) are attached to the support columns (26a, 26b, 26c) formed integrally with the brush holder stay 21, and one ends are held by the pressing portions (27a, 27b, 27c), and others. The end is set to push the rear end of the brush (22a, 22b, 22c).

  Next, the shape of the brush 22 will be described in detail with reference to FIG. Note that the shapes of the three brushes (22a, 22b, 22c) are all set to be substantially the same as that of the brush 22.

As shown in FIG. 4, the brush 22 includes a fixed portion 40 in which the pigtail 23 is disposed and fixed, and a sliding contact portion 41 that is integrally formed with the fixed portion 40 and disposed closer to the commutator 13 than the fixed portion 40. . Here, the shapes of the sliding contact portion 41 and the fixing portion 40 are the sliding contact portion 41 in the cross-sectional areas (A1, A2) of the facing surfaces (M1, M2) of the sliding contact portion 41 and the fixing portion 40 facing the commutator 13. The cross-sectional area A1 is smaller than the cross-sectional area A2 of the fixed portion 40. Specifically, the circumferential length (b1) of the facing surface M1 of the sliding contact portion 41 is set to a value smaller than the circumferential length (b2) of the facing surface M2 of the fixed portion 40. By forming the shapes of the sliding contact portion 41 and the fixed portion 40 as described above, the brush 22 is configured in a substantially T shape when viewed from the axial direction of the armature shaft 11.

Thus, by setting the circumferential length (b2) of the fixing portion 40 in the brush 22 to a certain length or more, the pigtail 23 can be sufficiently fixed and held. And by shortening the circumferential length (b1) of the sliding contact portion 41 in the brush 22, it is possible to shorten the "time for short-circuiting" between the adjacent commutator pieces (13b, 13b). The performance of the electric motor 2 can be improved.

Next, a structure for guiding the brushes (22a, 22b, 22c) toward the commutator 13 will be described with reference to FIGS. The brushes (22a, 22b, 22c) are surrounded by a brush holder (24a, 24b, 24c) having a substantially U-shaped cross section and a brush holder stay 21, and basically the brushes (22a, 22b, 22c) are brush holders ( 24a, 24b, 24c) and the brush holder stay 21 are guided toward the commutator 13. In detail, it is guided toward the commutator 13 by the structure described below.

As shown in FIGS. 5 and 6, the brush holder stay 21 is integrally provided with three pairs of protrusions (sliding contact guide means) (31, 32) (33, 34) (35, 36) on the inner peripheral edge. Is formed. The pair of projecting portions (31, 32) (33, 34) (35, 36) are formed so as to stand in the axial direction from the brush holder stay 21 and are circumferential in the brush holders (24a, 24b, 24c). It is arranged to face.

And both outer walls (31 of a pair of protrusion part (31, 32) (33, 34) (35, 36))
a, 32a) (33a, 34a) (35a, 36a) are supported in contact with the inner wall of the brush holder (24a, 24b, 24c). On the other hand, the inner walls (31b, 32b) (33b, 34b) (35b, 36b) of the pair of protrusions (31, 32) (33, 34) (35, 36) are brushes (22a, 22b, 22c). The sliding contact portions (41, 41, 41) are guided. Further, the fixing portions (40, 40, 40) of the brushes (22a, 22b, 22c) are guided toward the commutator 13 by the brush holders (24a, 24b, 24c).

As described above, the fixed portion 40 is guided by the brush holders (24 a, 24 b, 24 c), and the sliding contact portion 41 whose circumferential length is set smaller than the fixed portion 40 is provided on the brush holder stay 21. By guiding the pair of protrusions (31, 32) (33, 34) (35, 36) more independently and independently, the brushes (22a, 22b, 22c) are stably and reliably directed toward the commutator 13. It is possible to guide.

Further, by providing the sliding contact portion guide means on the brush holder stay 21 instead of the brush holder (24a, 24b, 24c), it is possible to use a brush holder that is generally used in an electric motor. Is possible.

Further, the sliding contact portions (41, 41, 41) of the brushes (22a, 22b, 22c) are held and guided from both sides in the circumferential direction by the pair of projecting portions (31, 32) (33, 34) (35, 36). Thus, the brush (22a, 22b, 22c) can be reliably guided in any rotation when the armature 10 rotates forward and backward.

(Second Embodiment) Next, a brush device 120 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a front view of the brush device according to the second embodiment of the present invention. In the brush device 120 of the second embodiment, unlike the brush device 20 of the first embodiment, only the high-speed brush 122c is set to have a short circumferential length of the sliding contact portion 141c, and the sliding contact portion is only in the guidance of the high-speed brush 122c. Guide means (135, 136) are used. Hereinafter, the structure of the brush device 120 will be described with reference to FIG.

The brush device 120 includes a substantially disc-shaped brush holder stay 121 made of resin, brush holders (124a, 124b, 124c) attached to the brush holder stay 121, and brush holders (124a, 124b, 124c). Three brushes (122a, 122b, 122c) that are held to move directly toward the commutator 13, and springs (125a, 125b, 125c) that urge the brushes (122a, 122b, 122c) toward the commutator 13. Is mainly provided.

Here, the brush 122 includes a positive brush 122a, a negative brush 122b, and a high-speed brush 122c, and these brushes (122a, 122b, 122c) are arranged so as to be in sliding contact with the commutator piece 13b of the commutator 13. Yes. Further, the springs (125a, 125b, 125c) are attached to the support columns (126a, 126b, 126c) formed integrally with the brush holder stay 121, and one ends are held by the pressing portions (127a, 127b, 127c). The end is set to push the rear end of the brush (122a, 122b, 122c).

The brush 122c includes a fixing portion 140c where the pigtail 123 is arranged and fixed, and a sliding contact portion 141c which is integrally formed with the fixing portion 141c and which is arranged closer to the commutator 13 than the fixing portion 141c. Here, the shape of the sliding contact portion 141c and the fixed portion 140c is such that the sectional area of the sliding contact portion 141c and the fixed portion 140c facing the commutator 13 is the same as the sectional area of the fixed portion 140c. It has a smaller shape. Specifically, the circumferential length of the facing surface of the sliding contact portion 141c is set to a value smaller than the circumferential length of the facing surface of the fixed portion 140c. By forming the shapes of the sliding contact portion 141c and the fixing portion 140c as described above, the brush 122c is configured in a substantially T shape when viewed from the axial direction of the armature shaft 11. Here, unlike the high-speed brush 122c, the positive brush 122a and the negative brush 122b do not have a structure in which the shape of the facing surface is changed between the fixed portion and the sliding contact portion, and the fixed portion and the sliding contact portion are integrated integrally. Is formed.

Next, a structure for guiding the high speed brush 122c toward the commutator 13 will be described. The brush 122c is surrounded by a brush holder 124c having a substantially U-shaped cross section and a brush holder stay 121. The brush 122c is basically guided toward the commutator 13 by the brush holder 124c and the brush holder stay 121. In detail, it is guided toward the commutator 13 by the structure described below.

The brush holder stay 121 is integrally formed with a pair of protruding portions (sliding contact guide means) (135, 136) on the inner peripheral edge. The pair of projecting portions (135, 136) are respectively erected in the axial direction from the brush holder stay 121, and are disposed in the brush holder 124c so as to face each other in the circumferential direction.

Then, both outer walls (135a, 136a) of the pair of protrusions (135, 136) are supported in contact with the inner wall of the brush holder 124c. On the other hand, both inner walls (135b, 136b) of the pair of protrusions (135, 136) guide the sliding contact portion 141c of the brush 122c. The fixing portion 140c of the brush 122c is guided toward the commutator 13 by the brush holder 124c. Here, the positive brush 122a and the negative brush 122b are guided toward the commutator 13 by the brush holders (124a, 124b) and the brush holder stay 121, unlike the high-speed brush 122c.

As described above, by setting the circumferential length of the sliding contact portion 141c of the high speed brush 122c to be short, the time for which the high speed brush 122c short-circuits between the adjacent commutator pieces (13b, 13b) can be shortened. Therefore, electromagnetic imbalance caused by short-circuiting between the adjacent commutator pieces (13b, 13b) from the high-speed brush 122c can be reduced, and sound and vibration generated during motor operation can be reduced.

(Third Embodiment) Next, a brush device 220 according to a third embodiment of the present invention will be described with reference to FIGS. Here, FIG. 8 is a perspective view of the brush device according to the third embodiment of the present invention, and FIG. 9 is a perspective view of the brush device viewed from the viewpoint F in FIG. FIG. 10 is a perspective view of a brush according to the third embodiment of the present invention, and FIG. 11 is an exploded perspective view of a portion surrounded by a range G in FIG.

As shown in FIG. 8, the commutator 213 provided in the electric motor in the third embodiment is formed in a disk shape. That is, the commutator 213 includes a disk-shaped commutator main body 213a and a plurality of commutator pieces 213b arranged radially at equal pitches on the end surface of the commutator main body 213a. The brush device 220 abuts the commutator 213 from the commutator piece 213b side of the commutator 213 and supplies current to the commutator 213.

8 and 9, the brush device 220 includes a substantially disc-shaped brush holder stay 221, brush holders (224a, 224b, 224c) attached to the brush holder stay 221, and brush holders (224a). , 224b, 224c) and three brushes (222a, 222b, 222c) that are held so as to be linearly movable toward the commutator 213, and a spring that biases the brushes (222a, 222b, 222c) toward the commutator 213. (225a, 225b, 225c). Further, the brush device 220 is provided with choke coils (228, 229) for noise countermeasures, and C / B 230 for countermeasures against heat-safe fail-safety.

Here, the brush 222 includes a positive brush 222a, a negative brush 222b, and a high-speed brush 222c, and these brushes (222a, 222b, 222c) are arranged so as to be in sliding contact with the commutator piece 213b of the commutator 213. Yes. Further, as shown in FIG. 11, the springs (225a, 25b, 25c) are arranged in the brush holders (224a, 224b, 224c), and one ends thereof are fixedly supported by the brush holders (224a, 224b, 224c). The other end is set so as to push the rear end portion of the brush (222a, 222b, 222c).

Next, the shape of the brush 222 will be described in detail with reference to FIG. Note that the shapes of the three brushes (222a, 222b, 222c) are all set to be substantially the same as that of the brush 222.

As shown in FIG. 10, the brush 222 includes a fixing portion 240 where the pigtail 223 is disposed and fixed, and a sliding contact portion 241 which is integrally formed with the fixing portion 240 and is positioned closer to the commutator 213 than the fixing portion 240. . Here, the shapes of the sliding contact portion 241 and the fixing portion 240 are the sliding contact portion 241 in the cross-sectional areas (A3, A4) of the facing surfaces (M3, M4) of the sliding contact portion 241 and the fixing portion 240 facing the commutator 213. The sectional area A3 is smaller than the sectional area A4 of the fixed portion 240. Specifically, the facing surface M3 of the sliding contact portion 241 is formed in a trapezoidal shape, and the circumferential length (b3) of the facing surface M3 of the sliding contact portion 241 is the circumferential length of the facing surface M4 of the fixing portion 240 ( It is set to a value smaller than b4).

Thus, the pigtail 223 can be sufficiently fixed and held by setting the circumferential length (b4) of the fixing portion 240 in the brush 222 to a certain length or more. Then, by setting the circumferential length (b3) of the sliding contact portion 241 in the brush 222 to be short, it is possible to shorten the “time for short-circuiting” between the adjacent commutator pieces (213b, 213b). The electric motor performance can be improved.

Next, a structure for guiding the brushes (222a, 222b, 222c) toward the commutator 213 will be described with reference to FIGS. The brushes (222a, 222b, 222c) are contained in brush holders (224a, 224b, 224c) having a substantially U-shaped cross section, and basically the brushes (222a, 222b, 222c) are brush holders (224a, 224b, 224c). ) To the commutator 13. In detail, it is guided toward the commutator 213 by the structure described below.

As shown in FIGS. 9 and 1, the brush holder stay 221 has insertion holes (sliding portion guide means) (h1, h2, h3) at positions corresponding to the respective brush holders (224a, 224b, 224c). Has been. The insertion holes (h1, h2, h3) are formed in substantially the same shape as the shape of the facing surface M3 of the sliding contact portions (241a, 241b, 241c) of the brushes (222a, 222b, 222c), respectively. The sliding contact portions (241a, 241b, 241c) of the brushes (222a, 222b, 222c) are inserted into the insertion holes (h1, h2, h3), and the brushes (h1, h2, h3) are brushed ( The sliding contact portions (241a, 241b, 241c) of 222a, 222b, 222c) are guided.

As described above, the fixing portion 240 is guided by the brush holders (224 a, 224 b, 224 c), and the sliding contact portion 241 whose circumferential length is set smaller than the fixing portion 240 is provided on the brush holder stay 21. By being separately guided independently by the insertion holes (h1, h2, h3), the brushes (222a, 222b, 222c) can be stably and reliably guided toward the commutator 13.

Further, by providing the sliding contact portion guide means on the brush holder stay 221 instead of the brush holder (224a, 224b, 224c), it is possible to use a brush holder generally used in an electric motor. Is possible.

Further, the armature rotates in the forward direction by holding and guiding the sliding contact portions (241a, 241b, 241c) of the brushes (222a, 222b, 222c) from both sides in the circumferential direction through substantially the same insertion holes (h1, h2, h3). The brushes (222a, 222b, 222c) can be reliably guided in any rotation during reverse rotation.

The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Electric motor with reduction gear 2 Electric motor 3 Reduction gear 5 Motor yoke 6 Magnet 10 Armature 11 Armature shaft 13, 213, 313 Commutator 13a, 213a, 313a Commutator main body 13b, 213b, 313b Commutator piece 14 Coil 20, 120, 220, 320 Brush device 21, 121, 221, 321 Brush holder stay 22, 122, 222, 322 Brush 22a, 122a, 222a Positive brush 22b, 122b, 222b Negative brush 22c, 122c, 222c High speed brush 23, 223, 323, 23a, 123a, 223a, 23b, 123b, 223b, 23c, 123c, 223c Pigtail 24, 124, 324, 24a, 124a, 224a, 24b, 124b, 224b, 24b, 124b 224b brush holder 25a, 125a, 225a, 25b, 125b, 225b, 25c, 125c, 225c, 325 spring
26a, 126a, 26b, 126b, 26c, 126c Posts 27a, 127a, 27b, 127b, 27c, 127c Presser portions 31, 32, 33, 34, 35, 36, 135, 136 Protruding portions (sliding contact portion guiding means)
31a, 32a, 33a, 34a, 35a, 36a, 135a, 136a Outer walls 31b, 32b, 33b, 34b, 35b, 36b, 135b, 136b Inner walls h1, h2, h3 Insertion holes (sliding contact guide means)
M1, M2, M3, M4 facing surface

Claims (4)

A motor yoke provided with a magnet on the inner periphery, an armature having a commutator rotatably disposed inside the motor yoke and connected to a coil, and a brush device having a brush slidably contacting the armature commutator. The brush device of the electric motor includes a brush holder that is formed in a substantially U-shaped cross-section, and holds the brush so as to be directly movable toward the commutator, and the brush is attached to the commutator. In an electric motor comprising: a spring that urges toward the brush; and a brush holder stay that is formed from a resin that is attached to the brush holder and guides the brush toward the commutator together with the brush holder;
The brush is disposed at a fixed portion where a pigtail is disposed and fixed, and a slide disposed at a position closer to the commutator than the fixed portion, and a cross-sectional area of a facing surface facing the commutator is set smaller than the fixed portion. The fixed portion is guided toward the commutator by the brush holder, and the sliding contact portion is guided by sliding contact guide means formed integrally with the brush holder stay,
The sliding contact portion guide means is formed of a pair of projecting portions that are erected in the brush holder stay in the axial direction and are disposed facing each other in the circumferential direction in the brush holder. Both outer walls abut against the brush holder, and both inner walls guide the sliding contact portion ,
The electric motor according to claim 1, wherein a circumferential length of the fixed portion of the brush is formed larger than an interval between inner walls of both the pair of projecting portions . The electric motor according to claim 1,
The electric motor is characterized in that the commutator is formed in a cylinder shape, and the brush is arranged so as to be linearly movable in the radial direction with respect to the commutator. The electric motor according to claim 1,
The electric motor is characterized in that the commutator is formed in a disk shape, and the brush is arranged so as to be linearly movable in the axial direction with respect to the commutator. In the electric motor according to claim 3,
The sliding contact portion guiding means is formed by an insertion hole formed in the brush holder stay in substantially the same shape as the facing surface of the sliding contact portion of the brush, and the sliding contact portion is guided by the insertion hole. An electric motor characterized by that.

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