JP2018078800A - Electric motor with brush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration of brushes slidably contacted to a commutator and reduce noise of an electric motor with the brushes.SOLUTION: A holder stay is provided to a power feeding unit of a motor part configured as a 4-pole motor, and a pair of brush holders 51 are provided to this holder stay while being shifted by 90 degrees from each other in a rotation direction around an armature shaft 17. A pair of brushes 52 slidably contacted with a commutator 18 are held so as to freely advance or retreat by the corresponding brush holders 51, and pressed toward the commutator 18 by twisted coil springs 53 attached to the holder stay. Coil main bodies 53a of the twisted coil springs 53 are arranged on an opposite side of the rotation direction of the armature shaft 17 to the corresponding brushes 52. Coil ends 53c of the twisted coil springs 53 are contacted to base ends 52a of the brushes 52 to incline the brushes 52 in the rotation direction side of the armature shaft 17 to a radial direction of the commutator 18.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an electric motor with a brush used as, for example, a drive source of a wiper device of an automobile.

  An electric motor with a brush provided with a commutator (commutator) fixed to an armature shaft and a pair of brushes slidably in contact with the commutator is used as a drive source for a wiper device of an automobile, for example. In the wiper device, the rotation of the armature shaft of the brushed electric motor is decelerated by a speed reducer and is converted into a swinging motion by a power conversion mechanism such as a link mechanism and transmitted to the wiper arm. Therefore, a one-way rotation type brushed electric motor in which an armature shaft rotates only in one direction is used for the wiper device.

  Such an electric motor with a brush includes a resin holder stay mounted on a yoke, and the brush is held by a pair of brush holders provided on the holder stay so as to be movable back and forth toward the commutator. Further, the brush is urged toward the commutator by the urging means, and elastically slidably contacts the commutator at the tip.

  For example, a torsion coil spring is used as the biasing means for biasing the brush toward the commutator. Since the torsion coil spring can be arranged adjacent to the brush or brush holder in the rotational direction, the radial dimension of the holder stay can be made smaller than the structure in which the compression spring is arranged side by side on the base end side of the brush. The attached electric motor can be reduced in size.

  For example, in Patent Document 1, in an electric motor with a brush configured as a four-pole motor, the brushes are arranged so as to be shifted from each other by 90 degrees in the rotation direction around the armature shaft and between the brushes of the holder stay. A pair of torsion coil springs is attached to the portion, and an electric motor with a brush is described in which each torsion coil spring urges each brush toward the commutator.

JP 2009-112095 A

  However, since the torsion coil spring is configured to push the base of the brush with the coil end protruding from the coil body, the direction in which the coil end pushes the brush is inclined with respect to the axial direction of the brush depending on the position of the brush in the advancing and retracting direction. The brush is in sliding contact with the commutator while being inclined in the rotational direction with respect to the radial direction of the commutator. And like the electric motor with a brush shown in patent document 1, in the right-and-left symmetrical structure which has arrange | positioned both torsion coil springs in the space between each brush, either one brush is always in a rotation direction. On the other hand, there is a problem in that the brush vibrates and the noise of the electric motor with the brush increases because the commutator is slidably contacted in a state inclined in the opposite direction.

  An object of the present invention is to reduce the noise of an electric motor with a brush by suppressing vibration of a brush that is in sliding contact with a commutator.

  The brushed electric motor of the present invention includes a yoke formed in a bottomed cylindrical shape, four magnets fixed to the inner surface of the yoke, rotatably accommodated in the yoke, and rotatably supported by the yoke. An armature shaft, a commutator and an armature core fixed to the armature shaft, an armature including an armature coil wound around the armature core, and a gear case fixed to the open end of the yoke; A speed reducer that is housed in the gear case and decelerates the rotation of the armature shaft, a pair of arc portions concentric with the armature shaft, and a pair of flat portions connected to the arc portion, A holder holder made of resin having a base formed in an oval shape, and provided on one arc portion of the base, A pair of brush holders formed in a tunnel shape having side walls, brushes attached to the brush holders and capable of moving forward and backward toward the commutator, and the corresponding brushes facing the commutator. And an urging member that is urged and tilted in a rotational direction with respect to a radial direction of the commutator, wherein the urging member includes a coil body and a pair protruding from the coil body. The pair of brush holders are formed on the top wall so as to extend in the moving direction of the brush, and a pigtail slit on which the pigtail provided on the brush is moved, and in the moving direction of the brush A coil end slit formed on one of the side walls so as to extend and to which the coil end is moved. The coil body is disposed 90 degrees apart from each other about the Chua axis in the rotational direction, and the coil body is attached to a support provided on the opposite side of the commutator from the rotational direction side with respect to the brush holder. Is provided with a bent portion that comes into contact with the proximal end of the brush, and the bent portion contacts the proximal end side of the brush with the side wall of the pair of side walls on which the support column is located. The brush is urged so that the contact point between the brush and the coil end is closer to the commutator than the line passing through the axial center of the coil body and perpendicular to the axial direction of the brush. Features.

  The electric motor with a brush according to the present invention is characterized in that the symmetry axis of the pair of brush holders is shifted in the rotation direction of the armature shaft with respect to the symmetry axis of the arc portion.

  The electric motor with brush according to the present invention is characterized in that a circuit breaker connected to one of the brushes is provided between the pair of brush holders in the holder stay.

  According to the present invention, since the pair of brushes are inclined by the urging member to the rotational direction side with respect to the radial direction of the commutator, both the brushes are inclined to the rotational direction side with respect to the commutator. Can be slid in contact. Thereby, the vibration of a brush can be suppressed and the noise of this electric motor with a brush can be reduced.

It is a top view of the rear wiper motor provided with the motor part which is one embodiment of the present invention. 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 around the brush holder shown in FIG. (a), (b) is sectional drawing which shows the holding structure of the brush by a brush holder, respectively. It is explanatory drawing which shows the sliding contact state to the commutator of each brush shown in FIG. As a comparative example, it is explanatory drawing which shows the sliding contact state to the commutator of each brush at the time of arrange | positioning both torsion coil springs between each brush.

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

  A rear wiper motor 11 shown in FIG. 1 is used as a drive source of a rear wiper device provided in a vehicle such as an automobile, and includes a motor unit 12 and a speed reducer 13.

  The motor unit 12 is an electric motor with a brush configured as a four-pole motor. The motor unit 12 includes a bottomed cylindrical yoke 15 with four magnets 14 fixed on the inner surface, and an armature 16 rotates inside the yoke 15. It is freely housed. The armature 16 includes an armature shaft 17 that is rotatably supported by the yoke 15, and a commutator 18 and an armature core 19 are fixed to the armature shaft 17. A plurality of armature coils (not shown) are wound around the armature core 19, and the coil ends of these armature coils are connected to the commutator 18. A power supply unit 21 is attached to the yoke 15, and a drive current supplied from a connector 22 provided in the speed reducer 13 is supplied to the armature 16 through the power supply unit 21. When a drive current is supplied to the armature 16, the motor unit 12 operates and the armature shaft 17 rotates in a predetermined direction. That is, the motor unit 12 is a one-way rotation type in which the armature shaft 17 rotates only in one direction.

  On the other hand, the speed reducer 13 includes a gear case 23 formed in a bathtub shape, and the gear case 23 is fixed to the opening end of the yoke 15 by two screw members 24 and 25. The distal end of the armature shaft 17 protrudes from the opening end of the yoke 15 and is disposed inside the gear case 23, and a worm shaft 26 rotatably accommodated in the gear case 23 is connected to the distal end. In the gear case 23, a worm wheel 27 is supported by a support shaft 28 and is rotatably accommodated. The worm wheel 27 is engaged with a worm 26a provided on the worm shaft 26.

  A power conversion mechanism 32 is accommodated in the gear case 23 in order to convert the rotational motion of the worm wheel 27 into a swing motion and transmit it to the output shaft 31. The power conversion mechanism 32 includes a pinion 33 fixed to the output shaft 31, and a power conversion member 34 is provided between the pinion 33 and the worm wheel 27. The power conversion member 34 includes a sector gear portion 34 a that meshes with the pinion 33, and a pin member 35 and an output shaft 31 that are provided at the axis of the sector gear portion 34 a are rotatably connected by a connecting plate 36. The power conversion member 34 includes an arm portion 34 b extending from the sector gear portion 34 a toward the worm wheel 27, and the tip of the arm portion 34 b is rotatably connected to the side surface of the worm wheel 27 by a pin member 37.

  The output shaft 31 is rotatably supported by the gear case 23, and a rear wiper arm (not shown) for wiping the rear window glass is fixed to the tip of the output shaft 31 that protrudes outside the gear case 23. When the motor unit 12 is operated to rotate the armature shaft 17, the rotation is decelerated by the worm 26 a and the worm wheel 27 and transmitted to the worm wheel 27, and the rotation of the worm wheel 27 is swung by the power conversion mechanism 32. It is converted into motion and output from the output shaft 31. As a result, the rear wiper arm fixed to the output shaft 31 is driven to swing by the rear wiper motor 11.

  Next, details of the power supply unit 21 provided in the motor unit 12 will be described.

  As shown in FIG. 2, the power supply unit 21 includes a holder stay 41. The holder stay 41 has a structure in which a base 42 and a guide wall 43 are integrally formed of a resin material. The base 42 has a plate shape perpendicular to the axial direction of the armature shaft 17, and has an oval shape corresponding to the cross-sectional shape of the yoke 15. That is, the base 42 has an oval shape including a pair of arc portions 42a and 42b concentric with the armature shaft 17 and a pair of flat portions 42c and 42d connected to the arc portions 42a and 42b. A through hole 42 e is provided in the shaft center of the base 42, and the armature shaft 17 and the commutator 18 are inserted through the through hole 42 e and penetrate the power supply unit 21. The guide wall 43 is formed integrally with the outer peripheral edge of the base 42, and when the power supply unit 21 is attached to the yoke 15, the outer surface of the guide wall 43 comes into contact with the inner surface of the yoke 15.

  A pair of brush holders 51 are provided on one arc portion 42 a of the base 42, and brushes 52 are attached to the brush holders 51, respectively.

  Each of these brush holders 51 is formed of a resin material integrally with the base 42, and has a tunnel shape including a top wall 51a and a pair of side walls 51b as shown in FIGS. As shown in FIG. 2, the pair of brush holders 51 are arranged 90 degrees apart from each other in the rotation direction of the armature shaft 17 with the center of the armature shaft 17, that is, the axis of the through hole 42e as the center. It faces the center of the through hole 42e. In addition, each brush holder 51 has an axis A1 that passes through an intermediate portion with respect to the rotation direction around the center of the armature shaft 17, that is, the axis of the through hole 42e, that is, the symmetry axis A1 with respect to the rotation direction of both brush holders 51. An axis passing through the center of the armature shaft 17 (axial center of the through hole 42e) and the central portion in the rotational direction of the arc portion 42a, that is, the axis of symmetry A2 of the arc portion 42a is arranged so as to deviate in the rotational direction of the armature shaft 17. Yes.

  On the other hand, each brush 52 is formed in a rectangular parallelepiped shape by a conductor such as carbon or graphite, and is mounted inside the corresponding brush holder 51. The width of the brush 52 is slightly smaller than the interval between the inner surfaces of the side walls 51b of the brush holder 51, and the brush 52 mounted on the brush holder 51 is held by the brush holder 51 and can move forward and backward toward the commutator 18. In other words, it is movable in the axial direction approaching / separating from the commutator 18.

  The holder stay 41 is provided with a pair of torsion coil springs 53 as urging members. The torsion coil spring 53 includes a coil main body 53a and a pair of coil ends 53b and 53c protruding from both axial ends of the coil main body 53a. The base 42 is provided with a pair of support columns 54 adjacent to the corresponding brush holders 51 on the opposite side to the rotation direction of the armature shaft 17 (counterclockwise direction side in FIG. 2). Each 53 is attached to the column 54 by inserting the coil body 53 a through the corresponding column 54. That is, the coil main body 53 a of each torsion coil spring 53 is disposed adjacent to the corresponding brush 52 on the opposite side to the rotation direction of the armature shaft 17.

  One coil end 53 b of the torsion coil spring 53 mounted on the column 54 is in contact with a support portion 55 provided on the holder stay 41, and the other coil end 53 c is a base end formed in a semi-columnar shape of the brush 52. 52a. Thereby, each brush 52 is urged toward the commutator 18 by the corresponding torsion coil spring 53, and the tip thereof is elastically slidably contacted with the outer peripheral surface of the commutator 18.

  As shown in FIGS. 3 and 4, the side wall 51b of the brush holder 51 is formed with a slit 51c extending in the axial direction so that the coil end 53c can move along the slit 51c in accordance with the forward / backward movement of the brush 52. It has become. A slit 51d extending in the axial direction is formed in the ceiling wall 51a of the brush holder 51, and a power feeding pigtail 52b provided on the top surface of the brush 52 according to the forward / backward movement of the brush 52 is a slit 51d. Can be moved along.

  The holder stay 41 is provided with a pair of power supply terminals 61a and 61b connected to the connector 22. A pigtail 52b for power supply of one brush 52 is connected to one power supply terminal 61a via a choke coil (not shown), The pigtail 52b for power supply of the other brush 52 is connected to the other power supply terminal 61b via a circuit breaker 62 and a choke coil (not shown). These power supply terminals 61a and 61b are connected to a power source such as a battery mounted on the vehicle via the connector 22, and when the rear wiper switch provided in the vehicle interior is turned on, the power supply terminals 61a and 61b are connected to the power supply terminals 61a and 61b. A drive current is supplied. When a drive current is supplied to the power supply terminals 61a and 61b, the drive current commutated at a predetermined timing by the brush 52 and the commutator 18 is supplied to the armature coil, and an electromagnetic force is generated in the armature 16 to generate the armature shaft 17. Rotates.

  In the rear wiper motor 11, the torsion coil spring 53 tilts the brush 52 toward the rotational direction of the armature shaft 17 with respect to the radial direction of the commutator 18 in order to reduce noise from the sliding contact portion between the brush 52 and the commutator 18. In this inclined state, the brush 52 is brought into sliding contact with the outer peripheral surface of the commutator 18.

  As shown in FIG. 5, when the brush 52 is in contact (sliding contact) with the commutator 18, the coil end 53 c of the torsion coil spring 53 passes through the axis of the coil body 53 a and is orthogonal to the axial direction of the brush 52. It is in contact with the base end 52a of the brush 52 on the side of the commutator 18 with respect to the line segment L. Therefore, the base end 52a formed in the semi-cylindrical shape of the brush 52 is pushed toward the opposite side to the rotation direction of the armature shaft 17 by the coil end 53c. On the other hand, since the width of the brush 52 held by the brush holder 51 is slightly smaller than the interval between the inner surfaces of the side walls 51b of the brush holder 51, the axial direction of the brush holder 51, that is, the radial direction of the commutator 18 is used. The armature shaft 17 can be tilted in the rotation direction inside the brush holder 51. Therefore, when the base end 52a formed in a semi-cylindrical shape of the brush 52 is pushed by the coil end 53c in the direction opposite to the rotation direction of the armature shaft 17, the brush 52 is distal to the radial direction of the commutator 18. Is inclined to the rotational direction side so as to be positioned on the rotational direction side of the armature shaft 17 with respect to the base end 52a.

  Here, the coil main bodies 53 a of the torsion coil springs 53 that bias the brushes 52 are all arranged on the opposite side of the rotation direction of the armature shaft 17 with respect to the corresponding brushes 52. Are inclined in the same direction with respect to the radial direction of the commutator 18, that is, in the rotational direction side of the armature shaft 17. Accordingly, both brushes 52 are in sliding contact with the outer peripheral surface of the commutator 18 in a state where the brush 52 is inclined to the rotational direction side of the armature shaft 17 with respect to the radial direction of the commutator 18. As a result, the noise of the motor unit 12 is reduced.

  On the other hand, in the modification shown in FIG. 6, since both torsion coil springs 53 are arranged between the brushes 52, the left side in FIG. 6 is biased by one torsion coil spring 53. The brush 52 is inclined to the rotational direction side of the armature shaft 17 with respect to the radial direction of the commutator 18 and vibration thereof is reduced. The other torsion coil spring 53 corresponds to the coil body 53a. Since the brush 52 on the right side in the figure pushed by the torsion coil spring 53 is arranged with respect to the radial direction of the commutator 18, the rotational direction of the brush 52 on the right side in FIG. The commutator 18 is slidably contacted in a state inclined to the opposite side. For this reason, in the configuration of the comparative example, the vibration of one brush can be suppressed, but the vibration of the other brush necessarily increases, thereby increasing the noise of the motor unit 12.

  As described above, in the motor unit 12 used in the rear wiper motor 11, the coil main body 53 a of the torsion coil spring 53 that biases each of the brushes 52 is all opposite to the brush 52 in the rotational direction of the armature shaft 17. Therefore, both brushes 52 can be inclined to the rotational direction side of the armature shaft 17 with respect to the radial direction of the commutator 18. Thereby, the vibration by the sliding contact with the commutator 18 of both the brushes 52 can be suppressed, and the noise of the motor part 12 can be reduced.

  Further, in the motor unit 12 used in the rear wiper motor 11, both the torsion coil springs 53 are arranged on the same side with respect to the corresponding brush 52, so that the torsion coil springs 53 have the same shape. Things can be used. As a result, it is only necessary to prepare a torsion coil spring 53 having one type of shape, so the number of parts of the motor unit 12 can be reduced and the cost thereof can be reduced.

  Further, in the motor unit 12 used in the rear wiper motor 11, both brushes 52 are arranged such that the axis of symmetry A1 is shifted to the rotational direction side of the armature shaft 17 with respect to the axis of symmetry A2 of the arc part 42a. Therefore, the pair of brush holders 51, the brush 52, and the torsion coil spring 53 can be efficiently arranged on one arc portion 42a. Thereby, the space efficiency of the holder stay 41 can be improved and the motor part 12, ie, the rear wiper motor 11, can be reduced in size.

  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-described embodiment, the present invention is applied to the power supply unit 21 of the motor unit 12 used in the rear wiper motor 11, but is not limited thereto, and is used as a drive source for a vehicle front wiper device, for example. The present invention may be applied to an electric motor with a brush used as a drive source for other devices, such as a power supply unit of a motor unit.

  Moreover, in the said embodiment, although the coil main body 53a of a pair of torsion coil spring 53 is arrange | positioned on the opposite side to the rotation direction of the armature shaft 17 with respect to each corresponding brush 52, it is not restricted to this. Instead, the coil main bodies 53a of the torsion coil springs 53 may be arranged on the rotation direction side of the armature shaft 17 with respect to the corresponding brushes 52, respectively.

  Furthermore, in the embodiment, the torsion coil spring 53 is used as the biasing member. However, the present invention is not limited to this, and each corresponding brush 52 is biased toward the commutator 18 and is also provided in the radial direction of the commutator 18. On the other hand, other urging members such as compression springs may be used as long as they can be inclined in the rotational direction.

11 Rear wiper motor 12 Motor part (electric motor with brush)
DESCRIPTION OF SYMBOLS 13 Reduction gear 14 Magnet 15 Yoke 16 Armature 17 Armature shaft 18 Commutator 19 Armature core 21 Feeding unit 22 Connector 23 Gear case 24, 25 Screw member 26 Worm shaft 26a Worm 27 Warm wheel 28 Support shaft 31 Output shaft 32 Power conversion mechanism 33 Pinion 34 Power conversion member 34a Sector gear part 34b Arm part 35 Pin member 36 Connecting plate 37 Pin member 41 Holder stay 42 Base 42a, 42b Arc part 42c, 42d Flat part 42e Through hole 43 Guide wall 51 Brush holder 51a Top wall 51b Side wall 51c, 51d Slit 52 Brush 52a Base end 52b Pigtail 53 Torsion coil spring 53a Coil body 53b, 53c Coil end 54 Post 55 Support portions 61a, 61b Feed terminal 2 circuit breaker A1, A2 symmetry axis L segment

Claims (3)

A yoke formed in a cylindrical shape with a bottom, four magnets fixed to the inner surface of the yoke, an armature shaft rotatably accommodated in the yoke and rotatably supported by the yoke, and fixed to the armature shaft A commutator and an armature core, and an armature having an armature coil wound around the armature core, and
A speed reducer having a gear case fixed to the open end of the yoke, and a speed reduction mechanism housed in the gear case for reducing the rotation of the armature shaft;
A resin holder stay having a pair of arc portions concentric with the armature shaft and a pair of flat portions connected to the arc portions, and having a base formed in an oval shape;
A pair of brush holders provided in one arc portion of the base and formed in a tunnel shape including a top wall and a pair of side walls;
A brush attached to the brush holder and capable of moving forward and backward toward the commutator;
A biasing member that biases the corresponding brush toward the commutator and inclines toward the rotational direction with respect to the radial direction of the commutator;
An electric motor with a brush,
The biasing member includes a coil body and a pair of coil ends protruding from the coil body,
The pair of brush holders are formed on the top wall so as to extend in the moving direction of the brush, a pigtail slit provided on the brush for moving the pigtail, and one side wall extending in the moving direction of the brush A coil end slit to which the coil end is moved, and arranged 90 degrees apart from each other in the rotational direction about the armature axis,
The coil body is attached to a support provided on the opposite side to the rotation direction side of the commutator with respect to the brush holder,
The coil end is provided with a bent portion that comes into contact with the proximal end of the brush, and the bent portion is disposed on the side wall on the side where the support column is located, of the pair of side walls. Energize the brush to contact the sides,
An electric motor with a brush, wherein a contact portion between the brush and the coil end is on the commutator side with respect to a line segment passing through an axis of the coil body and orthogonal to the axial direction of the brush. The electric motor with a brush according to claim 1,
An electric motor with a brush, wherein a pair of brush holders has a symmetry axis shifted in a rotation direction of the armature shaft with respect to a symmetry axis of the arc portion. In the electric motor with a brush according to claim 1 or 2,
An electric motor with a brush, wherein a circuit breaker connected to one of the brushes is provided between the pair of brush holders in the holder stay.

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