JP5869313B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor including a commutator fixed to an armature shaft, a brush slidably contacting the commutator, and a brush holder that slidably holds the brush toward the commutator.

  Conventionally, an electric motor including a commutator (commutator) fixed to an armature shaft, a brush slidably contacting the commutator, and a brush holder that slidably holds the brush toward the commutator is, for example, a vehicle such as an automobile. It is used as a drive source for the wiper device mounted on the machine. The electric motor used in the wiper device is equipped with a speed reduction mechanism so that a large output can be obtained even though it is small. As a result, the rotation of the armature shaft is reduced by the speed reduction mechanism to increase the torque, and then the power conversion of the link mechanism, etc. It is converted into a swing motion through a mechanism and transmitted to the wiper arm. The electric motor further includes a resin holder stay attached to a yoke that rotatably accommodates the rotation shaft, and the brush is slidably held toward the commutator by the brush holder provided in the holder stay. . Further, the brush is pressed toward the commutator by a spring, so that the tip end portion of the brush comes into sliding contact with the commutator in an elastic contact state.

  The electric motor used in the wiper device is mounted in a limited space (bulk head, etc.) of a vehicle such as an automobile, and therefore downsizing is essential. Electrical components (circuit breakers, etc.) are provided. That is, the development of an electric motor that can be miniaturized while mounting various electrical components is underway, and as such an electric motor, for example, the technique described in Patent Document 1 is known.

  The motor (electric motor) described in Patent Document 1 includes a pair of power supply brushes (brushes) formed in a substantially rectangular parallelepiped shape, and a pigtail (conductive wire) is electrically connected to each power supply brush. ing. Each power supply brush is slidably held by a brush holder and is pressed toward a commutator (commutator) by the spring force of each torsion coil spring.

JP 2009-112095 A (FIGS. 3 and 4)

  By the way, when the electric motor is reduced in size, the diameter dimension of the components constituting the electric motor is reduced accordingly, and consequently the diameter dimension of the commutator is also reduced. Thereby, the width dimension of the segment forming the commutator is also reduced. Then, even in the brush whose size is determined by the width dimension of the segment, the width dimension along the rotation direction of the commutator becomes small.

  Therefore, in the electric motor described in Patent Document 1 described above, since the brush formed in a substantially rectangular parallelepiped shape is used, the width dimension along the rotation direction of the commutator is reduced even on the base end side of the brush. Therefore, it is necessary to use a conductive wire having a smaller diameter. Here, when the diameter dimension of the conductive wire is reduced, the current density of the current flowing through the conductive wire increases, and the conductive wire is likely to generate heat and may be damaged.

  Therefore, it is conceivable to increase the width of the base end side of the brush along the rotation direction of the commutator. However, simply doing this makes the brush holder unstable by the brush holder. For example, when the application target of the brush is a forward / reverse rotation type electric motor, the brush is inclined to one side and the other side with forward / reverse rotation of the commutator, which causes generation of a large noise. In this case, when the brush is repeatedly inclined, the brush is cracked, and as a result, problems such as shortening the life of the electric motor may occur.

  An object of the present invention is to provide an electric motor that can cope with downsizing and high output of an electric motor without reducing the diameter of a conductive wire, and can extend the life of a brush while suppressing noise of the electric motor. There is.

Electric motor of the present invention, a commutator which is fixed to the armature shaft, includes a brush in sliding contact on the commutator, and a brush holder slidably holding towards the brush to the commutator, it can be normal and reverse rotation motor The brush has a proximal end portion on the radially outer side of the armature shaft and a distal end portion on the radially inner side of the armature shaft, and is along the axial direction of the armature shaft at the proximal end portion. A conductive wire is electrically connected to one side surface, and the distal end portion is formed to be narrow from both side surfaces along the rotation direction of the armature shaft of the base end portion, and the radial direction of the armature shaft is the length of the tip, longer than the length of the proximal portion along the radial direction of the armature shaft, in both side surfaces along the rotational direction of the armature shaft, and the group Parts respectively provided with a tapered surface between said distal end portion, the brush holder includes a pair of base end support portion supporting both sides along the proximal end portion in the rotation direction of the armature shaft, the distal portion A pair of distal end side support portions that are supported from both sides along the rotation direction of the armature shaft, and the length dimension of the base end side support portion along the radial direction of the armature shaft is set in the radial direction of the armature shaft. It is longer than the length dimension of the said front end side support part which follows.

  The electric motor of the present invention is characterized in that the tip side support portion is provided near the commutator of the brush holder.

  In the electric motor of the present invention, a curved surface portion that curves along the rotation direction of the armature shaft is formed at the base end portion, and a spring that presses the brush toward the commutator is brought into contact with the curved surface portion. Features.

  According to the electric motor of the present invention, the brush is formed from the proximal end portion on the radially outer side of the armature shaft and the distal end portion on the radially inner side of the armature shaft, and one side surface along the axial direction of the armature shaft of the proximal end portion The conductive wire is electrically connected to the base, and the distal end portion is formed to be narrow from both side surfaces along the rotation direction of the armature shaft at the base end portion. Further, the length dimension of the tip end portion of the brush along the radial direction of the armature shaft is made longer than the length dimension of the base end portion of the brush along the radial direction of the armature shaft. The brush holder has a pair of base end side support portions that support the base end portion of the brush from both sides along the rotation direction of the armature shaft, and a pair of tip ends that support the tip end portion of the brush from both sides along the rotation direction of the armature shaft. A side support portion is provided, and the length dimension of the base end side support portion along the radial direction of the armature shaft is made longer than the length dimension of the distal end side support portion along the radial direction of the armature shaft.

  Thereby, since the width dimension of the base end part of a brush can be ensured, making the front-end | tip part of a brush narrow, it can respond to size reduction of an electric motor. In addition, even if the electric motor is downsized, it is not necessary to reduce the diameter of the conductive wire, so that it is possible to suppress a decrease in the amount of power supplied to the commutator while suppressing heat generation of the conductive wire, thereby extending the life of the electric motor. Can correspond to output. Furthermore, since the brush holder supports the tip end and the base end of the brush from both sides along the rotation direction of the armature shaft by the pair of base end support portions and the pair of tip end support portions, the commutator rotates forward and backward. By suppressing the inclination of the brush toward one side and the other side, it is possible to extend the life of the brush while suppressing noise of the electric motor. Moreover, since the inclination to the one side and the other side of the brush can be suppressed, it is possible to deal with both forward and reverse rotating electric motors and one-way rotating electric motors. Furthermore, the length of the tip of the brush along the radial direction of the armature shaft is longer than the length of the base end of the brush along the radial direction of the armature shaft, so the electric motor can be made smaller and lighter. Can be planned. In addition, the length dimension of the base side support part along the radial direction of the armature shaft is longer than the length dimension of the tip side support part along the radial direction of the armature shaft, so that a sufficient brush stroke can be secured. Maintenance such as brush replacement is not necessary.

  According to the electric motor of the present invention, since the front end side support portion is provided near the commutator of the brush holder, a more sufficient brush stroke can be ensured.

  According to the electric motor of the present invention, a curved surface portion that curves along the rotation direction of the armature shaft is formed at the base end portion, and a spring that presses the brush toward the commutator is brought into contact with the curved surface portion. Regardless of the rotation direction, the brush can be slid smoothly with respect to the brush holder, and as a result, the occurrence of looseness and abnormal noise can be suppressed.

It is a top view of the rear wiper motor mounted in a vehicle. It is sectional drawing which shows the detail of the electric power feeding unit shown in FIG. It is a perspective view which shows the structure of the broken-line circle | round | yen A part of FIG. (A) is the perspective view which looked at the brush from the front end part side, (b) is the perspective view which looked at the brush from the base end part side. (A) is the top view which looked at the brush holder from the guide groove side, (b) is sectional drawing of the brush holder corresponding to (a). (A), (b) is explanatory drawing explaining the sliding state with respect to the brush holder of a brush. (A), (b) is explanatory drawing explaining the inclination state of the brush accompanying the forward / reverse rotation of a commutator.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  1 is a plan view of a rear wiper motor mounted on a vehicle, FIG. 2 is a cross-sectional view showing details of the power supply unit shown in FIG. 1, and FIG. 3 is a perspective view showing the structure of a broken line circle A portion of FIG. 4A is a perspective view of the brush viewed from the distal end side, FIG. 4B is a perspective view of the brush viewed from the proximal end side, and FIG. 5A is a brush holder viewed from the guide groove side. The top view and (b) respectively represent a cross-sectional view of the brush holder corresponding to (a).

  As shown in FIG. 1, a rear wiper motor 10 as an electric motor is used as a drive source of a rear wiper device (not shown) mounted on a rear hatch or the like of a vehicle such as an automobile, and includes a motor unit 20 and a speed reduction mechanism unit. 30.

  The motor unit 20 is configured as a 4-pole motor with a brush, and includes a yoke 21 formed into a bottomed cylindrical shape by pressing a steel plate as a magnetic body. A total of four magnets 22 (only two are shown in the figure) are fixed to the inner peripheral surface of the yoke 21, and an armature 23 is placed inside the magnet 22 via a predetermined gap (air gap). It is housed rotatably.

  The armature 23 includes an armature shaft 24 that is rotatably supported by the yoke 21, and a commutator 25 and an armature core 26 are fixed to the armature shaft 24. The commutator 25 includes a plurality of segments 25a (see FIG. 2), and a plurality of armature coils (not shown) are wound around the armature core 26. The coil end of each armature coil is electrically connected to each segment 25a.

  A power feeding unit 50 is mounted inside the opening side (left side in the figure) of the yoke 21, and the drive current supplied from the connector CN provided in the speed reduction mechanism unit 30 is supplied to the armature 23 via the power feeding unit 50. It comes to be supplied. When a drive current is supplied to the armature 23, the motor unit 20 operates and the armature shaft 24 rotates in a predetermined direction at a predetermined speed. Here, the motor unit 20 forming the rear wiper motor 10 is a one-way rotation type in which the armature shaft 24 rotates only in one direction.

  The speed reduction mechanism unit 30 includes a gear case 31 formed in a substantially bathtub shape by casting a molten aluminum material. The gear case 31 is fixed to the opening side of the yoke 21 by two fixing screws S.

  The distal end side of the armature shaft 24 protrudes from the opening side of the yoke 21 and extends into the gear case 31. The distal end portion of the armature shaft 24 has a worm shaft 32 rotatably accommodated in the gear case 31. The proximal portion is connected. In the gear case 31, a worm wheel 33 having a tooth portion 33 a is supported by a support shaft 34 and is rotatably accommodated. The tooth portion 33 a of the worm wheel 33 is provided integrally with the worm shaft 32. It is meshed with the worm 32a.

  A power conversion mechanism 36 is accommodated in the gear case 31 in order to convert the rotational motion of the worm wheel 33 into a swing motion and transmit the swing motion to the output shaft 35. The power conversion mechanism 36 includes a pinion 37 fixed to the output shaft 35, and a power conversion member 38 is provided between the pinion 37 and the worm wheel 33. The power conversion member 38 includes a sector gear portion 38 a that meshes with the pinion 37, and the pin member 39 provided at the axis of the sector gear portion 38 a and the output shaft 35 are rotatably connected by a connecting plate 40. The power conversion member 38 includes an arm portion 38 b extending from the sector gear portion 38 a toward the worm wheel 33, and a tip portion of the arm portion 38 b is rotatably connected to a side surface of the worm wheel 33 by a pin member 41.

  The output shaft 35 is rotatably supported by the gear case 31, and a rear wiper arm (not shown) for wiping the rear window glass is provided at a tip portion (not shown) of the output shaft 35 protruding outside the gear case 31. It is fixed. Thus, when the motor unit 20 is operated and the armature shaft 24 rotates, the rotation is decelerated by the worm 32 a and the worm wheel 33 to increase the torque, and is transmitted to the worm wheel 33. Then, the rotational motion of the worm wheel 33 is converted into a swing motion by the power conversion mechanism 36 and output from the output shaft 35 to the rear wiper arm, and the rear wiper arm performs a reciprocating wiping operation on the rear window glass.

  Next, the detailed structure of the power supply unit 50 attached to the motor unit 20 will be described.

  As shown in FIGS. 2 and 3, the power supply unit 50 is a holder stay in which the outer shape is formed in a substantially oval shape corresponding to the cross-sectional shape of the yoke 21 (see FIG. 1) by injection molding a resin material such as plastic. 51 is provided. As a result, the power supply unit 50 is mounted so as not to rotate relative to the yoke 21 without rattling.

  The holder stay 51 includes a base 52 and a guide wall 53 that are integrated with each other. The base 52 is a substantially oval plate that extends in a direction perpendicular to the armature shaft 24. That is, the base 52 includes a pair of arc portions 52a and 52b concentric with the armature shaft 24 and a pair of flat portions 52c and 52d connected to the arc portions 52a and 52b. A through hole 52 e is provided in the axis of the base 52, and the armature shaft 24 and the commutator 25 are inserted through the through hole 52 e, thereby penetrating the power supply unit 50. On the other hand, the guide wall 53 is integrally provided on the outer peripheral edge of the base 52 and extends in the axial direction of the armature shaft 24. The outer peripheral surface of the guide wall 53 comes into contact with the inner peripheral surface of the yoke 21 by attaching the power supply unit 50 to the yoke 21.

  A pair of brush holders 54 are integrally provided in one arc portion 52a of the base 52, and each brush holder 54 holds a brush 55 slidably. The brush holders 54 are arranged 90 degrees apart from each other in the rotation direction of the armature shaft 24 around the center of the armature shaft 24, that is, the axis of the through hole 52e. Each brush holder 54 is disposed on the arc portion 52a so that the sliding direction of the brush 55 is directed to the center of the through hole 52e. Furthermore, each brush holder 54 has an axis of symmetry A1 passing through the center of the armature shaft 24 and an intermediate portion of each brush holder 54, and an axis of symmetry A2 passing through the center of the armature shaft 24 and the central portion of the arc portion 52a. The armature shaft 24 is disposed on the arc portion 52a so as to deviate by a predetermined angle in the rotational direction of the armature shaft 24.

  As shown in FIGS. 2 and 4, the brush 55 is formed in a substantially rectangular parallelepiped shape by a conductor such as carbon or graphite, and includes a proximal end portion 55 a and a distal end portion 55 b. Here, in a state where the brush 55 is slidably held on the brush holder 54, the base end portion 55a is located on the radially outer side of the armature shaft 24, and the distal end portion 55b is located on the radially inner side of the armature shaft 24. It is located on the (commutator 25 side).

  One side surface 55c of the base end portion 55a along the axial direction of the armature shaft 24 is electrically connected to an end portion of a pigtail PG as a conductive wire. The pigtail PG is connected to the base end portion 55a (brush 55). Is supplied with a drive current. Here, the pigtail PG applied to the present embodiment is a conductive wire having a sufficient diameter and corresponding to a large output. In the normal operation state of the rear wiper motor 10, the pigtail PG generates heat and burns out. There is nothing wrong.

  The thickness dimension of the base end part 55a, that is, the width dimension of the base end part 55a along the rotation direction of the armature shaft 24 is set to a width dimension T1 that can connect the pigtail PG. Further, the thickness dimension of the distal end portion 55b, that is, the width dimension along the rotation direction of the armature shaft 24 of the distal end portion 55b is set to a width dimension T2 smaller than the width dimension T1 of the proximal end portion 55a (T2 <T1). . The distal end portion 55b is formed to be narrow from both side surfaces along the rotation direction of the armature shaft 24 of the base end portion 55a. Therefore, the brush 55 has a width around the reference line B along the radial direction of the armature shaft 24. It is formed to be a mirror image object in the direction.

  The length dimension along the radial direction of the armature shaft 24 of the base end portion 55a is set to L1, and the length dimension L1 of the base end portion 55a is set to a length dimension L1 that can connect the pigtail PG. That is, the length dimension L1 and the width dimension T1 of the base end portion 55a are set to substantially the same dimension (L1≈T1). On the other hand, the length dimension along the radial direction of the armature shaft 24 of the distal end portion 55b is set to a length dimension L2 longer than the length dimension L1 of the proximal end portion 55a (L2> L1).

  Thus, by making the width dimension T2 of the tip end portion 55b smaller than the width dimension T1 of the base end portion 55a, the brush 55 has a tapered shape in which the commutator 25 side is narrowed, and the rear wiper motor 10 is reduced in size. I am doing so. In addition, it is necessary to reduce the diameter dimension of the pigtail in accordance with the downsizing of the rear wiper motor 10 by setting the width dimension T1 and the length dimension L1 of the base end portion 55a to dimensions that can respectively connect the pigtail PG. The output of the rear wiper motor 10 is increased.

  Here, tapered surfaces TP are provided on both side surfaces of the brush 55 along the rotation direction of the armature shaft 24 and between the proximal end portion 55a and the distal end portion 55b. Each tapered surface TP ensures the rigidity of the brush 55 by smoothly connecting the base end portion 55a and the tip end portion 55b. Specifically, for example, even if a lateral stress that acts on the brush 55 is applied, the stress concentration is dispersed by the respective tapered surfaces TP as compared with the case where the base end portion 55a and the front end portion 55b are connected at a right angle. it can. As described above, by providing each tapered surface TP, the rigidity of the brush 55 is secured, and as a result, the brush 55 is prevented from being damaged early.

  A pair of curved surface portions CS that are curved along the rotation direction of the armature shaft 24 are provided on the side opposite to the distal end portion 55b side of the base end portion 55a. The curvature radius of each curved surface portion CS is set to R1, and the curved surface portion CS of one of the curved surface portions CS comes into contact with the tip curved portion 56c (see FIG. 3) of the torsion coil spring 56. Yes. Thus, the smooth sliding of the brush 55 with respect to the brush holder 54 is realized by bringing the tip curved portion 56c of the torsion coil spring 56 into contact with the curved surface portion CS. However, the base end portion 55a is not limited to the pair of curved surface portions CS, and one curved surface portion may be provided by increasing the curvature radius thereof.

  3 and 5, the brush holder 54 is formed in a substantially rectangular parallelepiped box shape, and is formed in a tunnel shape including a top wall 54a and a pair of side walls 54b. The brush holder 54 holds the brush 55 through a slight gap so that the brush 55 can move forward and backward smoothly toward the commutator 25 (see FIG. 2), that is, smoothly approach or separate from the commutator 25. It can be done.

  A guide groove 54c is formed in the top wall 54a so as to extend in the radial direction of the armature shaft 24. The guide groove 54c is directed from the outside along the radial direction of the armature shaft 24 of the top wall 54a toward the inside. It is formed by cutting out at a predetermined cut depth. The width dimension of the guide groove 54c is set to be slightly larger than the diameter dimension of the pigtail PG, so that the pigtail PG does not interfere with the guide groove 54c, thereby preventing the damage of the pigtail PG and the brush 55. Ensures smooth sliding.

  A spring slit 54d into which the torsion coil spring 56 enters is formed on one of the side walls 54b. The spring slit 54d also has an inner side from the outer side along the radial direction of the armature shaft 24 in the same manner as the guide groove 54c. It is formed by being cut out at a predetermined depth of cut. The width dimension of the spring slit 54d is set to be slightly larger than the diameter dimension of the torsion coil spring 56. As a result, the torsion coil spring 56 is caught by the spring slit 54d, and the pressing force of the brush 55 against the commutator 25 varies. I try to suppress it.

  As shown in FIG. 5, each side wall 54b includes a proximal end side support portion 54e and a distal end side support portion 54f. The opposing base end side support portions 54e that face each other are configured to support the base end portion 55a (see FIG. 4) of the brush 55 from both sides along the rotation direction of the armature shaft 24. The support part 54f supports the front-end | tip part 55b (refer FIG. 4) of the brush 55 from the both sides along the rotation direction of the armature shaft 24. As shown in FIG. As a result, the brush holder 54 can hold the tapered brush 55 slidably without being shaken toward the rotation direction of the armature shaft 24.

  Each front end side support portion 54f is provided at the inner side along the radial direction of the armature shaft 24, that is, at the front end of the brush holder 54 near the commutator 25, and the length dimension along the radial direction of the armature shaft 24 of each front end side support portion 54f. Is set to L3. On the other hand, the length dimension along the radial direction of the armature shaft 24 of each proximal end support part 54e is set to a length dimension L4 longer than the length dimension L3 of each distal end support part 54f (L4> L3). ).

  Thus, by providing each front end side support portion 54f at the front end of the brush holder 54 near the commutator 25 and setting its length dimension L3 to be short (L3 <L4), the base end portion 55a (length) of the brush 55 is set. The dimension L1) is supported by each base end side support part 54e (length dimension L4), and the tip part 55b (length dimension L2) of the brush 55 is supported by each tip side support part 54f (length dimension L3). Is done. Thereby, sufficient brush stroke of the brush 55 formed in the taper shape with respect to the brush holder 54 is ensured. Further, since the sliding portion between the brush 55 and the brush holder 54 becomes a portion of the base end portion 55a and each of the distal end side support portions 54f, the sliding area of the brush 55 with respect to the brush holder 54 is reduced, and the brush An increase in the sliding resistance 55 is suppressed.

  As shown in FIGS. 2 and 3, the holder stay 51 is provided with a pair of torsion coil springs (springs) 56. The torsion coil spring 56 includes a coil main body 56a, a coil base end portion 56b that forms one end side of the coil main body 56a, and a distal end bending portion 56c that forms the other end side of the coil main body 56a and is set to a curvature radius R2. I have. In addition, a pair of spring struts 57 are integrally provided on the base 52 of the holder stay 51 adjacent to the spring slits 54 d of the brush holders 54. The spring column 57 is inserted into the coil body 56 a of the torsion coil spring 56, that is, the spring column 57 supports the torsion coil spring 56.

  The coil base end portion 56 b is in contact with a support portion 58 provided in the vicinity of the guide wall 53 of the holder stay 51, and the distal end curved portion 56 c is in contact with one curved surface portion CS of the brush 55. Accordingly, each brush 55 is pressed toward the commutator 25 by each torsion coil spring 56, and the tip end portion 55 b of each brush 55 is elastically slidably contacted with the outer peripheral surface of the commutator 25.

  As shown in FIG. 2, the holder stay 51 is provided with a pair of power supply terminals 59 connected to the connector CN (see FIG. 1). One of the power supply terminals 59 is electrically connected to one pigtail PG via a choke coil (not shown), and the other of the power supply terminals 59 is a circuit breaker 60 and a choke coil (not shown). To the other pigtail PG. Each power supply terminal 59 is connected to a power source such as a battery mounted on the vehicle via a connector CN, and a drive current is supplied from the power source to each power supply terminal 59 based on an ON operation of a wiper switch provided in the vehicle interior. It has come to be. When a driving current is supplied to each power supply terminal 59, the driving current commutated at a predetermined timing by the brush 55 and the commutator 25 is supplied to the armature coil, and an electromagnetic force is generated in the armature 23 to generate an armature shaft. 24 rotates.

  Next, the operation of the rear wiper motor 10 formed as described above, in particular, the sliding state of the brush 55 forming the power supply unit 50 with respect to the brush holder 54 will be described in detail with reference to the drawings.

  6 (a) and 6 (b) are explanatory views for explaining the sliding state of the brush with respect to the brush holder, and FIGS. 7 (a) and 7 (b) are explanatory views for explaining the inclined state of the brush accompanying the forward / reverse rotation of the commutator. Each figure is shown.

  FIG. 6A shows a state in which the brush 55 is substantially new, and FIG. 6B shows a state in which the wear of the brush 55 has progressed. When the motor portion 20 (see FIG. 1) of the rear wiper motor 10 is operated and the tip portion 55b of the brush 55 and the commutator 25 are in sliding contact with each other, the tip portion 55b is gradually worn and shortened. At this time, since the radially outer side of the distal end curved portion 56c of the torsion coil spring 56 and the radially outer side of one curved surface portion CS provided on the proximal end portion 55a of the brush 55 are in contact with each other, the two are substantially point contact. It has become. Therefore, the spring force F of the torsion coil spring 56 acts on the commutator 25 substantially straight without twisting the brush 55 against the brush holder 54.

  When the tip 55b of the brush 55 is worn, the tip curved portion 56c side of the torsion coil spring 56 enters the spring slit 54d of the brush holder 54 and moves in the spring slit 54d. At this time, the torsion coil spring 56 does not interfere with the spring slit 54d, and thus moves smoothly. At this time, the pigtail PG (broken line) moves in the guide groove 54c (see FIG. 5), but the pigtail PG also moves smoothly because it does not interfere with the guide groove 54c. Furthermore, since the sliding area between the brush 55 and the brush holder 54 is reduced, the spring force F of the torsion coil spring 56 is transmitted to the tip 55b of the brush 55 with almost no loss in the middle thereof.

  Here, as the commutator 25 rotates in the direction of the arrow R, the brush 55 is inclined in the direction of the arrow M. However, since the motor unit 20 is a one-way rotation type, the brush 55 is in relation to the brush holder 54. Most of them don't shake. Therefore, the motor unit 20 is excellent in quietness that hardly generates noise due to the shakiness of the brush 55.

  For example, as shown in FIG. 7, when the motor unit 20 is a forward / reverse rotating electric motor, the brush 55 moves in the direction of the arrow M1 (counterclockwise) as the commutator 25 rotates in the direction of arrow FWD (clockwise). ) And the brush 55 is inclined in the arrow M2 direction (clockwise) as the commutator 25 rotates in the arrow REV direction (counterclockwise). In this case, as shown in FIG. 4, the brush 55 is formed to be a mirror image object in the width direction with the reference line B along the radial direction of the armature shaft 24 as the center, and therefore in the directions of the arrows M1 and M2. The inclination degree (inclination angle) of the brushes 55 is substantially equal to each other, thereby suppressing the occurrence of noise due to the shakiness of the brush 55 and suppressing the uneven wear of the tip 55b of the brush 55.

  As described above in detail, according to the rear wiper motor 10 according to the present embodiment, the brush 55 is moved from the radially outer base end portion 55 a of the armature shaft 24 and the radially inner distal end portion 55 b of the armature shaft 24. The pigtail PG is electrically connected to one side surface 55c along the axial direction of the armature shaft 24 of the base end portion 55a, and the distal end portion 55b is widened from both side surfaces along the rotation direction of the armature shaft 24 of the base end portion 55a. It was formed to be narrow. The length L2 of the tip 55b of the brush 55 along the radial direction of the armature shaft 24 is longer than the length L1 of the base end 55a of the brush 55 along the radial direction of the armature shaft 24. The brush holder 54 includes a pair of base end side support portions 54 e that support the base end portion 55 a of the brush 55 from both sides along the rotation direction of the armature shaft 24, and a tip end portion 55 b of the brush 55 in the rotation direction of the armature shaft 24. A pair of distal-end-side support portions 54f that are supported from both sides, and the length L4 of the proximal-end-side support portion 54e along the radial direction of the armature shaft 24 is set to the distal-end-side support portion 54f along the radial direction of the armature shaft 24. It was made longer than the length dimension L3.

  As a result, the width dimension T1 of the base end portion 55a of the brush 55 can be secured while the tip end portion 55b of the brush 55 is narrowed, so that the rear wiper motor 10 can be reduced in size. Even if the rear wiper motor 10 is downsized, it is not necessary to reduce the diameter of the pigtail PG. Therefore, it is possible to suppress the decrease in the amount of power supplied to the commutator 25 while suppressing the heat generation of the pigtail PG. To meet the demands for higher output and higher output. Further, the brush holder 54 supports the distal end portion 55b and the proximal end portion 55a of the brush 55 from both sides along the rotation direction of the armature shaft 25 by the pair of proximal end side support portions 54e and the pair of distal end side support portions 54f. Therefore, it is possible to extend the life of the brush 55 while suppressing the noise of the rear wiper motor 10 by suppressing the inclination of the brush 55 to one side and the other side due to the forward / reverse rotation of the commutator 25. Moreover, since the inclination to the one side and the other side of the brush 55 can be suppressed, both forward and reverse rotating electric motors and one-way rotating electric motors can be handled. Further, the length dimension L2 of the distal end portion 55b of the brush 55 along the radial direction of the armature shaft 24 is longer than the length dimension L1 of the proximal end portion 55a of the brush 55 along the radial direction of the armature shaft 24 (L2>). L1), the rear wiper motor 10 can be further reduced in size and weight. Further, since the length dimension L4 of the proximal end side support part 54e along the radial direction of the armature shaft 24 is longer than the length dimension L3 of the distal end side support part 54f along the radial direction of the armature shaft 24 (L4> L3). Sufficient brush strokes can be secured, and maintenance such as brush replacement need not be performed frequently.

  Further, according to the rear wiper motor 10 according to the present embodiment, since the front end side support portion 54f is provided at the front end of the brush holder 54 near the commutator 25, a more sufficient brush stroke can be secured.

  Furthermore, according to the rear wiper motor 10 according to the present embodiment, the base end portion 55a is formed with the curved surface portion CS that is curved along the rotation direction of the armature shaft 24, and the brush 55 is attached to the commutator 25 on the curved surface portion CS. Since the torsion coil spring 56 is pressed against the brush holder 54, the brush 55 can be slid smoothly with respect to the brush holder 54 regardless of the direction of rotation of the commutator 25, thereby suppressing the occurrence of looseness and noise. be able to.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the above embodiment, the present invention is applied to the rear wiper motor 10, but the present invention is not limited to this and may be applied to a drive source of a front wiper device of a vehicle such as an automobile. The present invention may be applied to a drive source of a device other than the wiper device.

  In the above embodiment, the torsion coil spring 56 is used as the spring. However, the present invention is not limited to this, and any wire can be used as long as the brush 55 can be pressed straight toward the commutator 25. Other springs such as a coil spring spirally formed to have a predetermined gap may be used.

10 Rear wiper motor (electric motor)
20 motor part 21 yoke 22 magnet 23 armature 24 armature shaft 25 commutator 25a segment 26 armature core 30 reduction mechanism part 31 gear case 32 worm shaft 32a worm 33 worm wheel 33a tooth part 34 support shaft 35 output shaft 36 power conversion mechanism 37 pinion 38 power Conversion member 38a Sector gear part 38b Arm part 39 Pin member 40 Connecting plate 41 Pin member 50 Power supply unit 51 Holder stay 52 Base 52a, 52b Arc part 52c, 52d Flat part 52e Through hole 53 Guide wall 54 Brush holder 54a Top wall 54b Side wall 54c Guide Groove 54d Slit for spring 54e Base end side support portion 54f Front end side support portion 55 Brush 55a Base end portion 55b Tip end portion 55c One side 56 Torsion coil spring (spring)
56a Coil body 56b Coil base end portion 56c Tip bent portion 57 Spring support 58 Support portion 59 Power supply terminal 60 Circuit breaker CN connector CS Curved surface portion PG Pigtail (conductive wire)
TP Taper surface S Fixing screw

Claims (3)

An electric motor including a commutator fixed to the armature shaft, a brush that is in sliding contact with the commutator, and a brush holder that slidably holds the brush toward the commutator,
The brush has a proximal end portion on the radially outer side of the armature shaft and a distal end portion on the radially inner side of the armature shaft, and a conductive wire on one side surface of the proximal end portion along the axial direction of the armature shaft. And the distal end portion is formed to be narrow from both side surfaces along the rotation direction of the armature shaft of the base end portion, and the length of the distal end portion along the radial direction of the armature shaft The dimension is longer than the length dimension of the base end portion along the radial direction of the armature shaft, on both side surfaces along the rotation direction of the armature shaft, and between the base end portion and the tip end portion, respectively. With a tapered surface,
The brush holder includes a pair of base end side support portions that support the base end portion from both sides along the rotation direction of the armature shaft, and a pair of tip ends that support the tip end portion from both sides along the rotation direction of the armature shaft. And a length dimension of the proximal end support section along the radial direction of the armature shaft is longer than a length dimension of the distal support section along the radial direction of the armature shaft. An electric motor characterized by   2. The electric motor according to claim 1, wherein the tip side support portion is provided near the commutator of the brush holder.   3. The electric motor according to claim 1, wherein a curved surface portion that is curved along a rotation direction of the armature shaft is formed at the base end portion, and a spring that presses the brush toward the commutator is formed on the curved surface portion. An electric motor characterized by contact.

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