JP6531206B2 - Motor with speed reduction mechanism - Google Patents

Description

  The present invention relates to a motor with a speed reduction mechanism, including a commutator fixed to an armature shaft, a brush slidingly contacting the commutator, and a brush holder slidably holding the brush toward the commutator.

  Conventionally, a motor with a speed reduction mechanism including a commutator fixed to an armature shaft, a brush slidingly contacting the commutator, and a brush holder slidably holding the brush toward the commutator is, for example, an automobile or the like. It is used as a drive source of a wiper device mounted on a vehicle of The motor with a reduction mechanism used in the wiper device is provided with a reduction mechanism so that a large output can be obtained while being small, whereby the rotation of the armature shaft is reduced by the reduction mechanism to increase torque, and then a link mechanism etc. It is converted into a swinging motion through the power conversion mechanism and transmitted to the wiper arm. The motor with speed reduction mechanism further includes a resin holder stay attached to a yoke that rotatably accommodates the rotation shaft, and the brush is slidably held by the brush holder provided on the holder stay toward the commutator. ing. Further, the brush is pressed by the spring toward the commutator, whereby the tip end portion of the brush comes into sliding contact with the commutator in an elastic contact state.

  In a motor with a reduction mechanism used for a wiper device, since it is mounted in a narrow space (bulk head etc.) of a vehicle such as an automobile, downsizing is essential, and further, needs for high performance To provide various electrical components (circuit breakers etc.). That is, development of a motor with a speed reduction mechanism that can be miniaturized while mounting various electrical components is in progress. Thus, for example, a technology described in Patent Document 1 is known as a motor devised to achieve miniaturization.

  The motor described in Patent Document 1 includes a pair of feed brushes (brushes) formed in a substantially rectangular parallelepiped shape, and pigtails (conductive wires) are electrically connected to the respective feed brushes. Each feeding brush is slidably held by the brush holder, and is pressed toward a commutator by means of the spring force of each torsion coil spring.

JP, 2009-112095, A (Drawing 3 and Drawing 4)

  By the way, when the motor is miniaturized, along with this, the diameter size of the components constituting the motor becomes smaller, and hence the diameter size of the commutator also becomes smaller. This also reduces the width dimensions of the segments forming the commutator. 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 smaller.

  Therefore, in the motor described in the above-mentioned patent document 1, since the brush formed in a substantially rectangular parallelepiped shape is used, the width dimension along the rotation direction of the commutator becomes small also on the base end side of the brush. You will be forced to use small diameter conductors. Here, if the diameter of the conductive wire is reduced, the current density of the current flowing through the conductive wire increases, and the conductive wire may easily generate heat and cause problems such as burnout.

  Therefore, it is conceivable to increase the width dimension of the proximal end side of the brush along the rotation direction of the commutator, but simply by doing so, the holding of the brush by the brush holder becomes unstable. For example, in the case where the application target of the brush is a forward or reverse motor, the brush is inclined to one side and the other side as the commutator rotates in the forward and reverse directions, which causes a large noise. In this case, repeated tilting of the brush may cause cracks in the brush, which in turn may cause problems such as shortening the life of the motor.

  An object of the present invention is to provide a motor with a speed reduction mechanism capable of coping with downsizing and high output without reducing the diameter of the conductive wire and suppressing noise and prolonging the life of the brush.

  The motor with a reduction mechanism according to the present invention includes a yoke formed in a bottomed cylindrical shape, a 4-pole magnet fixed to the inner peripheral surface of the yoke, and an armature rotatably accommodated in the yoke. The armature is wound around an armature shaft rotatably supported by the yoke, an armature core fixed to the armature shaft and disposed with a predetermined gap from the magnet, and the armature core A motor unit having an armature coil, a commutator fixed to the armature shaft, a gear case fixed to the opening side of the yoke, and a reduction mechanism housed in the gear case and decelerating the rotation of the armature shaft A base having a speed reduction mechanism portion having a pair of substantially parallel flat portions and an arc portion connected to the flat portions; A pair of brush holders formed integrally in a tunnel and having a ceiling wall and a pair of side walls, a brush slidably held by the brush holder and slidably contacting the commutator, A spring support rod extending in the axial direction of the armature shaft and integrally provided on the base in proximity to the brush holder, a coil body through which the spring support rod is inserted, and a coil forming one end of the coil body A power supply unit having a feed unit having a proximal end portion and a torsion coil spring having a coil distal end portion having a distal end curved portion forming the other end side of the coil main body The brush is integrally provided at a proximal end portion disposed radially outward of the armature shaft and the proximal end portion, and a radial direction of the armature shaft relative to the proximal end portion. A conductive wire is electrically connected to the surface of the proximal end facing the ceiling wall, and both sides of the distal end along the rotation direction of the armature shaft A distance between the surfaces is formed to be narrower than a distance between both side surfaces of the proximal end along the rotation direction of the armature shaft, and on both side surfaces of the brush along the rotation direction of the armature shaft, A tapered surface is provided between the proximal end and the distal end, and a surface of the proximal end of the brush facing the ceiling and a surface of the distal end facing the ceiling. The two side surfaces of the brush are connected to each other by an inclined surface, and the pair of brush holders are disposed 90 degrees apart from each other in the rotational direction of the armature shaft, and each of the brush holders is of the armature shaft. Outside along the radial direction A guide groove formed in the ceiling wall from the side toward the inside and formed in one of the side walls from the outside to the inside along the radial direction of the armature shaft, and a guide groove for guiding the conductive wire; A spring opening for receiving the coil distal end, a pair of proximal end supports for supporting both sides of the proximal end along the rotational direction of the armature shaft, and both sides of the distal end along the rotational direction of the armature shaft A plate-like member whose height relative to the axial direction of the armature shaft is formed higher than the top wall at a position adjacent to the brush holder on the base A circuit protection element is provided upright, and the conductive wire passes through the guide groove formed in the top wall and is electrically connected to a terminal provided on the upper portion of the circuit protection element. Special To.

  The motor with a reduction mechanism according to the present invention is characterized in that the circuit protection element is a circuit current limiting element.

  The motor with a reduction mechanism of the present invention is characterized in that the circuit current limiting element is a circuit breaker.

  In the motor with a reduction mechanism according to the present invention, the length dimension of the tip along the radial direction of the armature shaft on the surface side facing the top wall of each brush is the tip along the radial direction of the armature shaft The length dimension of the proximal portion along the radial direction of the armature shaft on the surface side of each brush facing the ceiling wall is longer than the length dimension of the side support portion, and the diameter of the armature shaft It is characterized in that it is formed shorter than the length dimension of the proximal end support portion along the direction.

  In the motor with a reduction mechanism according to the present invention, a curved surface portion which curves along the rotation direction of the armature shaft is formed at the base end portion, and the brush is pressed toward the commutator radially outward of the curved surface portion. The radially outer side of the torsion coil spring is substantially point-contacted, and the spring support posts provided corresponding to each of the pair of brush holders are all disposed on one side along the rotational direction of the armature shaft It is characterized by

  In the motor with a reduction mechanism according to the present invention, a symmetry axis passing through the center of the armature shaft and an intermediate portion of the pair of brush holders is with respect to a symmetry axis passing through the center of the armature shaft and the central portion of the arc portion. A pair of the brush holders are disposed in the arc portion so as to be offset by a predetermined angle in the rotational direction of the armature shaft.

  The motor with a reduction mechanism according to the present invention is characterized in that the power feeding unit has a holder stay whose outer shell is formed in a substantially oval shape by a resin material, and a pair of the brush holders integrally formed on the holder stay. Do.

  In the motor with a reduction mechanism according to the present invention, a through hole is provided in the axial center of the base, the armature shaft and the commutator are inserted into the through hole, and the distal end side support portion along the circumferential direction of the through hole It is characterized in that concave portions recessed outward in the radial direction of the through hole are provided on both sides.

  According to the motor with a reduction mechanism of the present invention, since the width dimension of the base end of the brush can be secured while narrowing the tip end of the brush, it is possible to cope with the downsizing of the motor with a reduction mechanism. In addition, since the diameter of the conductive wire does not need to be reduced even if the motor with the reduction mechanism is miniaturized, it is possible to suppress the decrease in the amount of power supplied to the commutator while suppressing the heat generation of the conductive wire. It is possible to cope with the life extension and high output. Furthermore, since the brush holder supports the distal end and the proximal end of the brush from both sides along the rotation direction of the armature shaft by the pair of proximal end support portions and the pair of distal end side support portions, the forward and reverse rotation of the commutator The inclination to one side and the other side of the brush accompanying with can be suppressed, and the life extension of a brush can be achieved, suppressing the noise of the motor with a reduction mechanism.

  Further, according to the motor with a reduction mechanism of the present invention, the tip end side supporting portion is provided closer to the commutator of the brush holder, so that a sufficient brush stroke can be secured.

  Furthermore, according to the motor with a reduction mechanism of the present invention, a curved surface portion curved along the rotation direction of the armature shaft is formed at the base end portion, and a spring pressing the brush toward the commutator contacts the curved surface portion. Therefore, regardless of the rotation direction of the commutator, the brush can slide smoothly with respect to the brush holder, and as a result, generation of rattling and abnormal noise can be suppressed.

It is a top view of the rear wiper motor carried in vehicles. 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 A part of FIG. (A) is the perspective view which looked at the brush from the front-end | tip part side, (b) is the perspective view which looked at the brush from the proximal end 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 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 a power feeding unit shown in FIG. 1, and FIG. 3 is a perspective view showing a structure of a broken circle A in FIG. 4 (a) is a perspective view of the brush viewed from the tip end side, FIG. 4 (b) is a perspective view of the brush viewed from the base end side, and FIG. 5 (a) is the brush holder viewed from the guide groove side The top view and (b) show the sectional view of the brush holder corresponding to (a), respectively.

  As shown in FIG. 1, a rear wiper motor 10 as a motor with a reduction mechanism is used as a drive source of a rear wiper device (not shown) mounted on a rear hatch of a vehicle such as an automobile. A mechanism unit 30 is provided.

  The motor unit 20 is configured as a 4-pole motor with a brush, and includes a yoke 21 formed in 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 drawing) are fixed to the inner peripheral surface of the yoke 21, and the armature 23 is provided inside the magnet 22 via a predetermined gap (air gap). It is housed rotatably.

  The armature 23 includes an armature shaft 24 rotatably supported by the yoke 21. 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 the armature core 26 is wound with a plurality of armature coils (not shown). The coil end of each armature coil is electrically connected to each segment 25a.

  A feed unit 50 is attached to the inside of the opening side (left side in the drawing) of the yoke 21, and the drive current supplied from the connector CN provided in the reduction mechanism unit 30 is transmitted to the armature 23 via the feed unit 50. It is supposed to be supplied. When a drive current is supplied to the armature 23, the motor unit 20 operates to rotate the armature shaft 24 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 and forming a molten aluminum material. The gear case 31 is fixed to the opening side of the yoke 21 by two fixing screws S.

  The tip end side of the armature shaft 24 protrudes from the opening side of the yoke 21 and extends inside the gear case 31, and at the tip portion of the armature shaft 24, the worm shaft 32 rotatably accommodated in the gear case 31. The proximal portions are linked. In the gear case 31, a worm wheel 33 having a tooth portion 33a is supported by a support shaft 34 and rotatably accommodated, and the tooth portion 33a of the worm wheel 33 is integrally provided on the worm shaft 32. It is engaged with the worm 32a.

  A power conversion mechanism 36 is accommodated in the gear case 31 in order to convert the rotational movement of the worm wheel 33 into a rocking movement and transmit the rocking movement 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 38a that meshes with the pinion 37. The pin member 39 provided at the axial center of the sector gear portion 38a and the output shaft 35 are rotatably connected by the connection plate 40. The power conversion member 38 also includes an arm portion 38 b extending from the sector gear portion 38 a toward the worm wheel 33, and a tip end portion of the arm portion 38 b is rotatably connected to the 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 disposed at the tip (not shown) of the output shaft 35 projecting to the outside of the gear case 31. It is fixed. Thereby, when the motor unit 20 operates and the armature shaft 24 rotates, the rotation is decelerated by the worm 32 a and the worm wheel 33, torque is increased, and the torque is transmitted to the worm wheel 33. Then, the rotational movement of the worm wheel 33 is converted into a rocking movement by the power conversion mechanism 36 and is output from the output shaft 35 to the rear wiper arm, and the rear wiper arm reciprocates the rear window glass.

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

  As shown in FIGS. 2 and 3, the feeder unit 50 is a holder stay whose outer shell is formed in a substantially oval shape corresponding to the cross-sectional shape of the yoke 21 (see FIG. 1) by injection molding of a resin material such as plastic. It has 51. Thus, the feeding 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 which are integrated with each other. The base 52 is a substantially oval plate which 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 axial center of the base 52, and the armature shaft 24 and the commutator 25 are inserted into the through hole 52 e, thereby penetrating the feed 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 is in contact with the inner peripheral surface of the yoke 21 by mounting the power supply unit 50 on the yoke 21.

  A pair of brush holders 54 are integrally provided on one arc portion 52 a of the base 52, and each brush holder 54 is configured to slidably hold the brushes 55. The brush holders 54 are disposed 90 degrees apart from each other in the rotational direction of the armature shaft 24 with respect to the center of the armature shaft 24, that is, the axial center of the through hole 52e. Each brush holder 54 is disposed in the arc portion 52a such that the sliding direction of the brush 55 is directed to the center of the through hole 52e. Furthermore, each brush holder 54 has a symmetry axis A1 passing through the center of the armature shaft 24 and an intermediate portion of each brush holder 54 with respect to a symmetry axis A2 passing through the center of the armature shaft 24 and the central portion of the arc 52a. The arc portion 52 a is disposed so as to be deviated 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 base end 55a and a tip 55b. Here, in a state where the brush 55 is slidably held by the brush holder 54, the base end 55a is located radially outside of the armature shaft 24, and the tip 55b is located radially inside of the armature shaft 24. It is positioned at (the commutator 25 side).

  The end of a pigtail PG as a conductive wire is electrically connected to one side surface 55c of the proximal end 55a along the axial direction of the armature shaft 24. The pigtail PG has a proximal end 55a (brush 55). The drive current is supplied to the Here, the pigtail PG applied to the present embodiment is a conductive wire corresponding to a large output having a sufficient diameter dimension, and in a normal operation state of the rear wiper motor 10, the pigtail PG generates heat and burns off. There is nothing to do.

  The thickness dimension of the proximal end 55a, that is, the width dimension of the proximal end 55a along the rotational direction of the armature shaft 24 is set to the width dimension T1 to which the pigtail PG can be connected. Further, the thickness dimension of the distal end portion 55b, that is, the width dimension along the rotational 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 55a (T2 <T1) . The distal end 55b is formed to be narrower from both side surfaces of the proximal end 55a along the rotation direction of the armature shaft 24. Therefore, the brush 55 has a width centered on the reference line B along the radial direction of the armature shaft 24. It is formed to be a mirror image in the direction.

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

  As described above, by making the width dimension T2 of the distal 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 miniaturization of the rear wiper motor 10 is realized. It is like that. Also, by setting the width dimension T1 and the length dimension L1 of the base end 55a to such dimensions that the pigtail PG can be connected respectively, it is necessary to reduce the diameter of the pigtail corresponding to the downsizing of the rear wiper motor 10. As a result, the output of the rear wiper motor 10 can be increased.

  Here, tapered surfaces TP are provided on both side surfaces of the brush 55 along the rotational direction of the armature shaft 24 and between the base end 55 a and the tip 55 b. Each tapered surface TP smoothly connects the proximal end 55 a and the distal end 55 b to secure the rigidity of the brush 55. Specifically, for example, even if a transverse stress such as pricking on the brush 55 is applied, stress concentration is dispersed by each tapered surface TP as compared with the case where the proximal end 55a and the distal end 55b are connected at a right angle. it can. As described above, by providing the tapered surfaces TP, the rigidity of the brush 55 is secured, and thus the brush 55 is prevented from being damaged prematurely.

  A pair of curved surface portions CS curved along the rotation direction of the armature shaft 24 is provided on the opposite side of the proximal end 55a from the distal end 55b side. The radius of curvature of each curved surface portion CS is set to R1, and the tip curved portion 56c (see FIG. 3) of the torsion coil spring 56 comes in contact with one curved surface portion CS of each curved surface portion CS. There is. As described above, by bringing the end curved portion 56c of the torsion coil spring 56 into contact with the curved surface portion CS, smooth sliding of the brush 55 with respect to the brush holder 54 is realized. However, the base end 55 a is not limited to providing the pair of curved surface portions CS, but the radius of curvature may be increased to provide one curved surface portion.

  As shown in FIGS. 3 and 5, the brush holder 54 is formed in a substantially rectangular box shape, and is formed in a tunnel shape having a top wall 54a and a pair of side walls 54b. The brush holder 54 holds the brush 55 through a slight gap, whereby the brush 55 can be moved back and forth smoothly toward the commutator 25 (see FIG. 2), that is, smoothly approached or separated 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, and the guide groove 54c is directed inward from the outside along the radial direction of the armature shaft 24 of the top wall 54a. It is formed by notching at a predetermined cutting depth. The width dimension of the guide groove 54c is set to a size slightly larger than the diameter dimension of the pigtail PG, whereby the pigtail PG does not interfere with the guide groove 54c and thus the damage of the pigtail PG is prevented. Smooth sliding is ensured.

  A spring slit 54d into which the torsion coil spring 56 is formed is formed in one of the side walls 54b, and the spring slit 54d is also formed from the outside along the radial direction of the armature shaft 24 similarly to the guide groove 54c. Cut to a predetermined depth of cut toward the The width dimension of the spring slit 54d is set to a size slightly larger than the diameter dimension of the torsion coil spring 56, whereby the torsion coil spring 56 is caught on the spring slit 54d or the like, and the pressing force of the brush 55 against the commutator 25 varies. I try to suppress the

  As shown in FIG. 5, each side wall 54b includes a proximal end support 54e and a distal end support 54f. The base end side supporting portions 54e opposed to 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 54 f supports the tip 55 b (see FIG. 4) of the brush 55 from both sides along the rotational direction of the armature shaft 24. Thus, the brush holder 54 can slidably hold the tapered brush 55 without swinging in the rotational direction of the armature shaft 24.

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

  Thus, the proximal end 55a (the length) of the brush 55 is provided by providing the distal end side supporting portions 54f at the distal end of the brush holder 54 near the commutator 25 and setting the length dimension L3 short (L3 <L4). The dimension L1) is supported by each proximal end support portion 54e (length dimension L4), and the tip end 55b (length dimension L2) of the brush 55 is supported by each tip end support portion 54f (length dimension L3) Be done. Thus, a sufficient brush stroke of the tapered brush 55 with respect to the brush holder 54 is secured. In addition, since the sliding portion between the brush 55 and the brush holder 54 is a portion of the base end portion 55a and a portion of each distal end side supporting portion 54f, the sliding area of the brush 55 against the brush holder 54 is reduced. The increase in the sliding resistance of 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 body 56a, a coil base end 56b forming one end side of the coil body 56a, and the other end side of the coil body 56a, and a tip curved portion 56c set to a curvature radius R2 Have. Further, on the base 52 of the holder stay 51, a pair of spring columns 57 are integrally provided in proximity to the side of the spring slits 54d of the brush holders 54. The spring support 57 is inserted into the coil body 56 a of the torsion coil spring 56, that is, the spring support 57 supports the torsion coil spring 56.

  The coil base end 56 b is in contact with a support 58 provided in close proximity to the guide wall 53 of the holder stay 51, and the tip curve 56 c is in contact with one curved surface CS of the brush 55. As a result, each brush 55 is pressed toward the commutator 25 by each torsion coil spring 56, and the tip 55b of each brush 55 comes into sliding contact with the outer peripheral surface of the commutator 25 elastically.

  As shown in FIG. 2, the holder stay 51 is provided with a pair of feed terminals 59 connected to the connector CN (see FIG. 1). One of the feed terminals 59 is electrically connected to one of the pigtails PG via a choke coil (not shown), and the other of the feed terminals 59 is a circuit breaker 60 and a choke coil (not shown). And is connected to the other pigtail PG. Each feed terminal 59 is connected to a power source such as a battery mounted on a vehicle via a connector CN, and the drive current is supplied from the power source to each feed terminal 59 based on the on operation of a wiper switch provided in the vehicle compartment. It is supposed to be Then, when the drive current is supplied to each feed terminal 59, the drive current diverted 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, and the armature shaft is produced. 24 are supposed to rotate.

  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) illustrate the sliding state of the brush relative to the brush holder, and FIGS. 7 (a) and 7 (b) illustrate the inclined state of the brush according to the forward and reverse rotation of the commutator. The figures are shown respectively.

  FIG. 6 (a) shows a state where the brush 55 is substantially new, and FIG. 6 (b) shows a state where the wear of the brush 55 has progressed. When the motor unit 20 (see FIG. 1) of the rear wiper motor 10 operates and the tip 55b of the brush 55 and the commutator 25 come in sliding contact, the tip 55b gradually wears and shortens. At this time, since the radial outer side of the distal end curved portion 56c of the torsion coil spring 56 and the radial outer side of one curved surface portion CS provided at the base end 55a of the brush 55 are in contact with each other, It has become. Therefore, the spring force F of the torsion coil spring 56 acts on the commutator 25 substantially straightly without causing the brush 55 to cling to the brush holder 54.

  As the distal end 55b of the brush 55 is worn away, the distal end curved portion 56c 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, since the torsion coil spring 56 does not interfere with the spring slit 54d, it moves smoothly. Also, at this time, the pigtail PG (broken line) moves in the guide groove 54c (see FIG. 5), but the pigtail PG does not interfere with the guide groove 54c, and therefore, moves smoothly. 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 55 b of the brush 55 with almost no loss.

  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 contact with the brush holder 54. There is almost no backlash. Therefore, the motor unit 20 is excellent in quietness which hardly generates noise due to the rattling of the brush 55.

  For example, as shown in FIG. 7, when the motor unit 20 is a forward / reverse rotation type electric motor, the brush 55 moves in the arrow M1 direction (counterclockwise direction) as the commutator 25 rotates in the arrow FWD direction (clockwise). The brush 55 is inclined in the direction of arrow M2 (clockwise) as the commutator 25 rotates in the direction of the arrow REV (counterclockwise). In this case, as shown in FIG. 4, the brush 55 is formed so as to be a mirror image in the width direction centering on the reference line B along the radial direction of the armature shaft 24. The degree of inclination (angle of inclination) is balanced and substantially equal, thereby suppressing partial wear of the tip 55 b of the brush 55 while suppressing the generation of noise due to rattling 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 formed by the radially outer base end 55 a of the armature shaft 24 and the radially inner end 55 b of the armature shaft 24. The pigtail PG is electrically connected to one side surface 55c of the proximal end 55a along the axial direction of the armature shaft 24, and the distal end 55b has a width from both side surfaces along the rotational direction of the armature shaft 24 of the proximal end 55a. It was formed to be narrow. Further, the length dimension L2 of the tip 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 55a of the brush 55 along the radial direction of the armature shaft 24. In the brush holder 54, a pair of proximal end support portions 54 e supporting the proximal end 55 a of the brush 55 from both sides along the rotational direction of the armature shaft 24 and the distal end 55 b of the brush 55 in the rotational direction of the armature shaft 24. A pair of distal end side supporting portions 54f are provided to support from both sides along the length, and a length dimension L4 of the proximal end side supporting portion 54e along the radial direction of the armature shaft 24 is set to the distal side supporting portion 54f along the radial direction Longer than the length dimension L3.

  As a result, the width dimension T1 of the base end 55a of the brush 55 can be secured while narrowing the tip 55b of the brush 55, so that the rear wiper motor 10 can be made smaller. In addition, since it is not necessary to reduce the diameter size of the pigtail PG even if the rear wiper motor 10 is miniaturized, 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. Support high power and high output. Furthermore, the brush holder 54 supports the distal end 55 b and the proximal end 55 a of the brush 55 from both sides along the rotational direction of the armature shaft 25 by the pair of proximal support portions 54 e and the pair of distal support portions 54 f. Therefore, it is possible to suppress the noise of the rear wiper motor 10 and prolong the life of the brush 55 while suppressing the inclination to the one side and the other side of the brush 55 accompanying the forward and 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, it can respond to both forward and reverse rotation type electric motor and one-way rotation type electric motor. Furthermore, the length dimension L2 of the tip 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 55a of the brush 55 along the radial direction of the armature shaft 24 (L2> L1), the rear wiper motor 10 can be made smaller and lighter. In addition, since the length dimension L4 of the proximal end side support portion 54e along the radial direction of the armature shaft 24 is longer than the length dimension L3 of the distal end side support portion 54f along the radial direction of the armature shaft 24 (L4> L3) Sufficient brush stroke can be secured, and frequent maintenance such as brush replacement is not required.

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

  Furthermore, according to the rear wiper motor 10 according to the present embodiment, the base end 55a is provided with the curved surface portion CS that curves along the rotation direction of the armature shaft 24, and the brush 55 is used as the commutator 25 for the curved surface portion CS. Since the torsion coil spring 56 is pressed in contact, the brush 55 can slide smoothly against the brush holder 54 regardless of the rotation direction of the commutator 25, and as a result, generation of rattling and abnormal noise is suppressed. be able to.

  It goes without saying that the present invention is not limited to the above embodiment, and various changes can be made without departing from the scope of the invention. For example, although the present invention is applied to the rear wiper motor 10 in the above embodiment, 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 another device other than the wiper device.

  In the above embodiment, although the torsion coil spring 56 is used as the spring, the present invention is not limited to this, and as long as the brush 55 can be pressed straight toward the commutator 25, the distance between the lines can be Other springs such as a coil spring formed in a spiral shape so as to have a predetermined gap may be used.

10 Rear wiper motor (motor with reduction mechanism)
DESCRIPTION OF SYMBOLS 20 motor part 21 yoke 22 magnet 23 armature 24 armature shaft 25 commutator 25a segment 26 armature core 30 deceleration mechanism part 31 gear case 32 worm shaft 32a worm 33 worm wheel 33a tooth part 34 spindle 35 output shaft 36 power conversion mechanism 37 pinion 38 power Converting member 38a Sector gear portion 38b Arm portion 39 Pin member 40 Connecting plate 41 Pin member 50 Feeding unit 51 Holder stay 52 Base 52a, 52b Arc portion 52c, 52d Flat portion 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 support 54f Front end support 55 Brush 55a Base end 55b End 55c One side 56 Torsion coil spring (spring)
56a Coil body 56b Coil base end 56c Tip curved portion 57 Spring support 58 Support portion 59 Feeding terminal 60 Circuit breaker CN connector CS Curved surface PG Pigtail (conductive wire)
TP taper surface S fixing screw

Claims (8)

A yoke having a bottomed cylindrical shape,
A 4-pole magnet fixed to the inner circumferential surface of the yoke;
An armature rotatably accommodated in the yoke;
The armature is wound around the armature shaft rotatably supported by the yoke, an armature core fixed to the armature shaft and disposed with a predetermined gap from the magnet, and the armature core An armature coil, and a commutator fixed to the armature shaft;
A motor unit having
A gear case fixed to the opening side of the yoke;
A reduction mechanism housed in the gear case and decelerating the rotation of the armature shaft;
A speed reduction mechanism having
A base comprising a pair of substantially parallel flat portions and an arc portion connected to the flat portions;
A pair of brush holders formed integrally in the base and formed in a tunnel shape, having a top wall and a pair of side walls;
A brush slidably held by the brush holder and in sliding contact with the commutator;
A spring support extending axially of the armature shaft and integrally provided on the base in proximity to the brush holder;
Torsion including a coil main body through which the spring support is inserted, a coil base end forming one end of the coil main body, and a coil distal end having a tip curved portion forming the other end of the coil main body Coil spring,
A feed unit having
A motor with a reduction mechanism that can rotate in both forward and reverse directions,
The brush is
A proximal end disposed radially outward of the armature shaft;
A distal end provided integrally with the proximal end and disposed radially inward of the armature shaft than the proximal end;
Have
A conductive wire is electrically connected to the surface of the base end facing the top wall,
A distance between both side surfaces of the distal end portion along the rotation direction of the armature shaft is formed narrower than a distance between both side surfaces of the proximal end portion along the rotation direction of the armature shaft.
Tapered surfaces are provided on both sides of the brush along the rotational direction of the armature shaft, and between the proximal end and the distal end, respectively.
The surface of the proximal end of the brush facing the ceiling wall, the surface of the tip facing the ceiling wall, and both sides of the brush are connected to each other by inclined surfaces.
The pair of brush holders are disposed 90 degrees apart from each other in the rotational direction of the armature shaft,
Each said brush holder is
A guide groove formed on the top wall from the outside along the radial direction of the armature shaft and guiding the conductive wire;
A spring opening formed on one of the side walls from the outside along the radial direction of the armature shaft to the inside and receiving the coil distal end of the torsion coil spring;
A pair of proximal support portions supporting both sides of the proximal end portion along the rotation direction of the armature shaft;
A pair of distal side support portions supporting both sides of the distal end portion along the rotational direction of the armature shaft;
Have
The base is provided with a plate-like circuit protection element erected at a position adjacent to the brush holder and having a height relative to the axial direction of the armature shaft that is higher than the top wall.
The motor with a speed reduction mechanism, wherein the conductive wire is electrically connected to a terminal provided in an upper portion of the circuit protection element through the guide groove formed in the top wall.   The motor with a reduction mechanism according to claim 1, wherein the circuit protection element is a circuit current limiting element.   The motor with a reduction mechanism according to claim 2, wherein the circuit current limiting element is a circuit breaker.   The motor with a reduction mechanism according to any one of claims 1 to 3, wherein the length dimension of the tip portion along the radial direction of the armature shaft on the surface side facing the top wall of each brush is The length of the proximal end portion of the distal end side supporting portion along the radial direction of the armature shaft is longer than that of the proximal end portion along the radial direction of the armature shaft on the surface side facing the top wall of each brush A motor with a speed reduction mechanism, wherein a length dimension is formed shorter than a length dimension of the proximal end support portion along a radial direction of the armature shaft.   The motor with a reduction gear mechanism according to any one of claims 1 to 4, wherein a curved surface portion which curves along the rotation direction of the armature shaft is formed at the base end portion, and radially outward of the curved surface portion. The radially outer side of the torsion coil spring for pressing the brush toward the commutator is substantially in point contact with the outside in the radial direction, and the spring support provided corresponding to each of the pair of brush holders is all of the armature shaft A motor with a reduction mechanism, characterized in that it is disposed on one side along the rotational direction.   The motor with a reduction mechanism according to any one of claims 1 to 5, wherein a symmetry axis passing through a center of the armature shaft and an intermediate portion of the pair of brush holders is a center of the armature shaft and the arc portion. A motor with a speed reduction mechanism, wherein a pair of the brush holders are arranged in the circular arc portion so as to be offset at a predetermined angle in the rotational direction of the armature shaft with respect to a symmetry axis passing through the central portion.   The motor with a reduction mechanism according to any one of claims 1 to 6, wherein the power supply unit includes a holder stay whose outer shell is formed in a substantially oval shape by a resin material, and a pair of the holder stays integrally formed on the holder stay. And a brush holder.   The motor with a reduction mechanism according to any one of claims 1 to 7, wherein a through hole is provided in an axial center of the base, the armature shaft and the commutator are inserted into the through hole, and the through hole is formed. A motor with a reduction gear mechanism, wherein concave portions recessed outward in the radial direction of the through hole are provided on both sides of the tip end side support portion along the circumferential direction.

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