JP2014033493A - Electric rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric rotary machine which suppresses roughness of a commutator face, avoids influence of the roughness and can improve brush life.SOLUTION: A lower end face of a brush 24 slidably contacts with a surface of a commutator 27 with rotation of a rotation shaft 2 to be worn out. In the brush 24, one inclined face in a radial direction and an upper end face of the brush 24 are energized and depressed from two directions of an axial direction of the commutator 27 and the radial direction toward a rotation shaft center J1 by first and second springs 35a and 35b. In the brush 24, a side in a radial direction side inclines to an energizing side in the axial direction by a prescribed angle, and a cross section shape of a side parallel to the axial direction is formed in a parallelogram. A position where the brush 24 is brought into contact with the commutator 27 moves forward in the axial direction on the commutator 27 with wear of a sliding face 31. Even if roughness occurs on a surface of the commutator 27, the sliding face 31 moves to a new contact position with wear of the brush 24.

Description

  The present invention relates to an electric rotating machine used for an electric motor and a generator.

  2. Description of the Related Art Conventionally, there has been known an electric motor capable of performing electric power supply to an armature, that is, a rotor by performing sliding contact between a commutator and a brush for an electric rotating machine. For example, an electric power steering device (EPS) is known. Is used. The brush of the electric motor is made of carbon, and is housed in a metal sleeve provided in the brush holder for energizing the commutator provided in the rotor, and is pushed from the sleeve to the commutator side and protrudes by the spring. It is provided as possible (see, for example, Patent Document 1).

JP 2004-304865 A

  However, in the above electric motor, the position where the brush and the commutator are in contact with each other is constant, and the brush and the commutator surface are always in contact with each other and rotating while being rubbed. It becomes the main factor of life deterioration. The surface of the commutator surface is roughened by sparks and wear due to energization and vibration from the brush. When the commutator surface is rough, there is a case where the amount of wear of the brush increases and a contact failure between the brush and the commutator may occur. As a result, the brush life may be deteriorated and the motor efficiency may be reduced. In particular, the electric motor used in the electric power steering apparatus is required to have a long life and high reliability.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric rotating machine that can suppress the roughness of the commutator surface, avoid the influence of the roughness, and improve the brush life. It is to provide.

  In order to solve the above problem, an electric rotating machine according to claim 1 is provided with a cylindrical commutator fixed on a rotating shaft and a circumferential direction of the commutator, and is slid on the commutator. A plurality of brushes that are in contact with each other, a first biasing member that biases each brush in the axial direction of the commutator, and a first biasing member that biases each brush toward the axial center in the radial direction of the commutator. Each of the brushes, and a side surface perpendicular to the axial direction is inclined at a predetermined angle to one of the axial directions with respect to a radial direction of the commutator. The gist of the sliding contact surface is that it moves forward in the axial direction of the brush in the direction of the inclination of the brush as the wear progresses.

  According to the above configuration, in the electric rotating machine, the brush is moved in the two axial directions of the commutator by the two urging members and the radial direction toward the axial center as the brush slides on the rotating commutator. Be energized. In the brush, the side surface perpendicular to the axial direction of the brush is inclined at a predetermined angle to one side of the axial direction of the commutator, and the position of the sliding surface of the brush that contacts the commutator surface is in the axial direction of the brush Move side forward. As a result, it is possible to suppress the surface roughness of the commutator and to avoid adverse effects due to the surface roughness. As a result, the brush life can be improved, and the life of the electric motor can be extended and the reliability can be improved.

  The gist of the invention described in claim 2 is that, in the electric rotating machine according to claim 1, the cross-sectional shape of the side surface parallel to the axial direction of the brush is formed in a parallelogram.

  According to the said structure, the cross-sectional shape of the side surface parallel to the axial direction of a brush is formed in the electric rotary machine in the parallelogram. As a result, even if the surface of the commutator is rough, the sliding contact surface of the brush has a certain length in the axial direction and moves to a new contact position on the commutator surface as the brush wears. To do. As a result, even if the commutator surface is rough, the influence of the roughness can be avoided by the movement of the sliding contact surface, and the brush life can be improved.

  According to the present invention, it is possible to provide an electric rotating machine that can suppress the roughness of the commutator surface, avoid the influence of the roughness, and improve the brush life.

1 is a longitudinal sectional view showing a schematic configuration of an electric motor according to an embodiment of the present invention. Schematic which shows the relationship between the commutator of FIG. 1, and a brush. The longitudinal cross-sectional view which shows the relationship between the commutator of FIG. 2, and a brush. Schematic which shows the contact positional relationship of a brush and a commutator in the abrasion state of a brush.

Next, as an example of an embodiment of the present invention, an electric motor used as a drive source in an electric power steering apparatus for assisting the steering force of the steering will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a schematic configuration of an electric motor according to an embodiment of the present invention. The electric motor 1 is an inner rotor type brushed DC (direct current) motor. As shown in FIG. 1, the electric motor 1 includes an annular armature (rotor) 3 that is coupled to the rotary shaft 2 so as to be able to rotate together, an annular stator (stator) 4 surrounding the armature 3, and A cylindrical motor housing 5 including a yoke 20 that houses the armature 3 and the stator 4 and a housing 28 is provided. For example, in the case of a column assist type EPS motor, a worm speed reducer (not shown) is arranged on the left side in the axial direction of the electric motor 1 in FIG.

  The electric motor 1 of this embodiment is supported rotatably on the inner side of a stator 4 having a permanent magnet 7 fixed to the inner periphery of a yoke 20 made of a magnetic material having a substantially bottomed cylindrical shape. And a plurality of power supply brushes (hereinafter referred to as brushes) 24 for supplying power to the armature 3.

  The armature 3 includes an armature core 6 and a commutator 27 that are fixed to the rotating shaft 2 and rotate integrally with the rotating shaft 2. In the present embodiment, the rotary shaft 2 is pivotally supported by bearings 29a and 29b provided on the housing 28 that closes the bottom 20a of the yoke 20 and the opening end 20b of the yoke 20, respectively. It is arranged along. The armature 3 is rotatably accommodated in the yoke 20 with the armature core 6 disposed at the axial position corresponding to the permanent magnet 7 by the bearings 29a and 29b. Further, the open end 20b of the yoke 20 protrudes radially outward, and the protruding portion is fixed to the housing 28 by a plurality of bolts (not shown).

  Furthermore, the armature core 6 includes a plurality of (for example, twelve) teeth 30 formed of laminated steel plates (for example, silicon steel plates) made of a magnetic material extending radially outward in the radial direction. A winding (motor coil) 9 is wound around each of the teeth 30. The permanent magnet 7 that faces the outer periphery of the armature core 6 with a certain gap and is fixed to the inner periphery of the stator 4 has N poles and S poles alternately along the circumferential direction. A plurality (for example, four poles) of magnetic poles are formed so as to be.

  On the other hand, the commutator 27 is provided on one end side in the axial direction of the armature core 6, has a columnar shape having a diameter smaller than that of the armature core 6, and is a peripheral surface of the cylindrical body 32 fixed to the rotating shaft 2. A plurality of (for example, twelve) segments 33 are fixed to each other. Specifically, the cylindrical body 32 is disposed in the yoke 20 on the opening end 20b side (left side in FIG. 1) from the armature core 6 and is made of a conductive material (for example, copper, carbon, etc.). The segments 33 formed from are arranged at predetermined intervals along the peripheral surface of the cylindrical body 32. The segments 33 are electrically connected to the windings 9 wound around the teeth 30.

  In addition, the electric motor 1 of the present embodiment has a plurality of (in this embodiment, for example, two to four) arranged along the circumferential direction so as to surround the commutator 27 on the radially outer side of the commutator 27. A brush 24 is provided. The brush 24 is made of carbon (for example, graphite) mixed with metal powder (for example, copper). Each brush 24 is housed in a resin brush holder 34 and is urged by coil springs (hereinafter referred to as first and second springs; first and second urging members) 35a and 35b. Thereby, it is provided on the commutator 27 side so as to be able to protrude and arranged so that the tip thereof is in sliding contact with each segment 33 disposed on the peripheral surface of the commutator 27. In addition, one end of a pigtail 25 for supplying power to the brush 24 is electrically connected to the end surface of the brush 24 opposite to the surface in contact with the commutator 27. The other end of the pigtail 25 is electrically connected to a battery (not shown).

  The brush 24 has two pairs of brushes, each of which has a positive electrode side and a negative electrode side brush arranged at an opposite position of about 180 ° on the outer peripheral side of the commutator 27 and arranged at an adjacent position with an interval of about 90 ° in the circumferential direction. Positive and negative voltages corresponding to the motor rotation are applied to the brush pairs (four) by an external controller (ECU) (not shown). The brushes 24 are in sliding contact with the segments 33 corresponding to the rotational position of the commutator 27, thereby energizing the windings 9 connected to the segments 33 of the commutator 27.

  That is, in the electric motor 1 of the present embodiment, which is a DC motor with brushes, the segments 33 that are in sliding contact with the brushes 24 are moved by the rotation of the armature 3, so Switching (rectification) is performed. The electric motor 1 generates motor torque based on electromagnetic force (electromagnetic attractive force and repulsive force) generated between the winding 9 and each magnetic pole formed on the stator 4 side by energizing the winding 9. It is the composition to do.

  The electric motor 1 is attached and fixed to a worm speed reducer (not shown), for example, in a column assist type electric power steering device, by a flange portion that protrudes radially outward from the left end of the housing 28 in the axial direction. 2 is coupled to the worm shaft rotating shaft via a boss 37 for transmitting torque.

  Further, in the electric motor 1 of the present embodiment, an external ECU for controlling the electric motor 1 is connected to a connector (not shown) taken out from the housing 28 of the electric motor 1 via a harness. The ECU is equipped with a control circuit unit including a drive circuit that supplies a drive current to the winding 9 of the electric motor 1 and a control circuit that controls the drive circuit.

  With the above configuration, the drive current controlled by the ECU is supplied to each winding 9 of the electric motor 1. Thereby, a rotating magnetic field is generated in the winding 9, torque is generated in the permanent magnet 7, and the armature 3 is rotationally driven.

2 is a schematic diagram showing the relationship between the commutator and the brush in FIG. 1, and FIG. 3 is a longitudinal sectional view showing the relationship between the commutator and the brush in FIG.
As shown in FIG. 2, the brush 24 has a first and second springs (coil springs) 35 a and 35 b that are arranged in the axial direction of the commutator 27 and the radial direction toward the rotation axis center J1. One side surface in the radial direction (left side slope in the figure) and upper end surface are urged and pressed, respectively. The sliding contact surface 31 that is the lower end surface of the brush 24 is worn by sliding with the surface of the commutator 27 as the rotating shaft 2 rotates. In the brush 24, the side surface on the radial side is inclined at a predetermined angle toward the biasing side in the axial direction, and the cross-sectional shape of the side surface parallel to the axial direction is formed into a parallelogram. 24 and the commutator 27 move within the contact range B in the direction indicated by the arrow A in the figure.

  As shown in FIG. 3, the brush 24 is attached to the brush holder 34 fixed to the housing 28 (see FIG. 1) via first and second springs 35 a and 35 b and a pressing member 36. The brush 24 and the commutator 27 are in contact with each other on a sliding contact surface 31 having a certain length in the axial direction. The brush 24 is biased by a pressing member 36 provided at the tip of the first spring 35 a, and the pressing member 36 causes the slope of one side (left side in the figure) of the opposite side whose cross-sectional shape is inclined to a parallelogram. It is pressed and moves forward in the axial direction. The amount of movement at this time is proportional to the amount of wear of the brush 24. The pressing member 36 is a non-conductive member, for example, formed of a resin material. The sliding contact surface 31 which is the lower end surface of the brush 24 slides on the commutator 27, and the brush 24 is worn. Then, as the brush 24 is urged and pressed in the radial direction by the second spring 35b and wears, the upper end surface moves downward in the radial direction.

  Next, the movement of the brush 24 as the wear of the brush 24 progresses will be described. FIG. 4 is a schematic diagram showing a contact position relationship between the brush and the commutator in a state where the brush is worn.

As shown in FIG. 4, first, in the initial state, the brush 24 is urged and pressed by the first and second springs 35 a and 35 b and the pressing member 36, and slides on the surface of the commutator 27. Wear of the slidable contact surface 31 which is the lower end surface of 24 occurs (FIG. 4A).
Next, as wear progresses, the contact position of the brush 24 with the commutator 27 moves to the right in the figure (FIG. 4B).
Subsequently, when the surface of the commutator 27 is roughened due to sparks or the like (FIG. 4C), the sliding contact surface 31 moves to the right over time due to wear, and the surface of the commutator 27 is roughened. It passes through the generated site (FIG. 4 (d)).
Further, the brush 24 reaches the final state with the right end portion in contact with the brush holder 34 (FIG. 4E).

  Next, the operation and effect of the electric motor 1 according to the present embodiment configured as described above will be described.

  According to the above configuration, the lower end surface of the brush 24 is worn in sliding contact with the surface of the commutator 27 as the rotating shaft 2 rotates. At this time, the brush 24 has one side surface and an upper end surface in the radial direction of the brush 24 from the two directions of the axial direction of the commutator 27 and the radial direction toward the rotation axis center J1 by the first and second springs 35a and 35b. Each is energized and pressed. Further, the brush 24 is formed such that the side surface on the radial side is inclined at a predetermined angle toward the biasing side in the axial direction, and the cross-sectional shape of the side surface parallel to the axial direction is formed into a parallelogram. For this reason, as the sliding contact surface 31 of the brush 24 is worn by sliding between the brush 24 and the commutator 27, the position where the brush 24 and the commutator 27 are in contact moves forward in the axial direction on the commutator 27. . Further, since the side surface on the radial direction side of the brush is inclined forward in the moving direction of the brush, even when the surface of the commutator 27 is rough, the sliding contact surface 31 is caused by the wear of the brush 24. Move to a new contact position forward in the axial direction.

  This suppresses the surface roughness of the commutator 27 that is generated when the brush 24 is in sliding contact with the commutator 27, increases the amount of wear of the brush 24 due to the occurrence of the roughness, and poor contact between the brush 24 and the commutator 27. Such adverse effects can be avoided. As a result, the brush life can be improved, and in particular, the long life and high reliability required for the electric motor 1 used in the electric power steering apparatus can be realized.

  As described above, according to the present embodiment, it is possible to provide an electric motor that can suppress the roughness of the commutator surface, avoid the influence of the roughness, and improve the brush life.

  As mentioned above, although embodiment which concerns on this invention was described, this invention can also be implemented with another form.

  In the present embodiment, the present invention has been embodied and described by taking the electric motor 1 as an example. However, the present invention is not limited to this and may be used as a generator.

  According to the above configuration, the radial side surface of the brush 24 is inclined in the axial direction toward the armature 3 side, but is not limited thereto, and may be inclined to the side opposite to the armature 3. At this time, the first spring 35 a and the pressing member 36 are provided on the armature 3 side of the brush 24.

  Moreover, although the cross-sectional shape of the side surface parallel to the axial direction of the brush 24 has been described as a parallelogram in the above-described embodiment, the present invention is not limited to this, and a pseudo parallelogram whose opposite sides are not equal in inclination angle may be used.

Furthermore, in the above-described embodiment, the number of brushes of the electric motor 1 is four. However, the number of brushes is not necessarily limited thereto, and a plurality of brush pairs or a pair of brushes 24 arranged with the commutator 27 interposed therebetween. The electric motor 1 may be formed. Also, the number of segments 33 may be embodied in other numbers.

  In the above embodiment, an example in which the electric motor (DC motor with brush) 1 is applied to a so-called column assist type of an electric power steering apparatus (EPS) is shown, but the present invention is not limited to this, and a pinion assist type or rack assist type electric motor is used. You may apply to a power steering apparatus. Moreover, you may apply to the apparatus (for example, electric oil pump apparatus etc.) used for the other use using the same electric motor.

1: electric motor, 2: rotating shaft, 3: armature (rotor), 4: stator (stator), 5: motor housing, 6: armature core, 7: permanent magnet, 9: winding (motor coil) 20: yoke, 20a: bottom, 20b: open end, 24: brush, 25: pigtail, 26: armature core, 27: commutator, 28: housing, 29a, 29b: bearing, 30: teeth,
31: sliding surface, 32: cylindrical body, 33: segment, 34: brush holder,
35a, 35b: first and second springs (first and second urging members), 36: pressing member,
37: Boss
J1: Center of rotation axis

Claims (2)

A cylindrical commutator fixed on the rotation axis;
A plurality of brushes that are provided along the circumferential direction of the commutator and that are in sliding contact with the commutator;
A first biasing member that biases each brush in the axial direction of the commutator;
A second biasing member that biases each brush toward the axial center in the radial direction of the commutator;
Each brush has a side surface perpendicular to the axial direction inclined at a predetermined angle with respect to the radial direction of the commutator at one angle in the axial direction, and the sliding surface of each brush follows the progress of wear. An electric rotating machine that moves forward in the inclination direction side of the brush in the axial direction. The electric rotating machine according to claim 1,
The electric rotating machine is characterized in that a cross-sectional shape of a side surface parallel to the axial direction of the brush is formed in a parallelogram.

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