JP2003259607A - Brush for motor and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the low noise of a motor formed by elastically bringing the inside diameter side face of a brush energized from the outside diameter side into sliding contact with the outer periphery of a commutator integrally fitted onto a motor shaft. <P>SOLUTION: This motor is constructed in a following way: By forming a sliding surface 8d formed into a recessed curved face along the outer periphery of the commutator 6 and an inclined surface 8e formed into a recessed curved surface meeting the curved surface of the sliding contact surface 8d, an edge 8f crossing the inclined surface 8e of the sliding surface 8d is formed so as to be straight when viewed from the front side, and a sliding-contact width S in the direction of a motor shaft 4 is maintained so as to be roughly constant. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a brush in an electric motor for constituting an electric component such as a vehicle and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, some electric motors of this type include
A brush urged by an ammo is brought into sliding contact with the outer peripheral surface of the commutator that is integrally fitted to the outer peripheral surface of the motor shaft,
There is a structure in which power is supplied to a coil wound around the outer periphery of a motor shaft. In such a structure, the brush is mounted on the side of the motor yoke that constitutes the electric motor, is installed in a brush holder that is formed radially around the motor shaft, and does not depend on the ammunition arranged on the outer diameter side of the brush. It is known that the brush is biased toward the radial side so that the inner diameter side surface of the brush comes into elastic contact with the outer peripheral surface of the commutator. In this case, as the brush, in order to stabilize the posture when the brush is internally supported by the brush holder, a brush that is larger than a sliding contact portion that slidably contacts the commutator outer peripheral surface is used. Therefore, the brush is, for example, as shown in FIG.
0a is formed with a concave curved sliding contact surface 10b located at one end in the motor axial direction along the commutator outer peripheral surface,
The one having an inclined surface 10c which is located at the other portion in the motor axial direction and is inclined so as to be separated from the outer peripheral surface of the commutator is used.

[0003]

However, in the conventional brush 10, the inclined surface 10 following the sliding contact surface 10b is used.
Since c is formed in a flat plate shape (flat shape), when the sliding contact surface 10b is cut into a curved surface, the sliding contact surface 10b and the inclined surface 10c intersect each other.
As shown in FIG. 8, the one edge portion 10d has a curved shape in the circumferential direction (a curved shape in which the intermediate portion bulges toward the inclined surface). For this reason, the sliding contact width of the sliding contact surface 10b that faces the motor axis direction changes so as to become wider during relative rotation with the commutator (motor shaft). By the way, on the outer peripheral surface of the commutator, a plurality of segments are arranged adjacent to each other while being insulated in the circumferential direction, and a plurality of slight steps are formed between the respective segments. Therefore, the sliding sound when the sliding contact surface of the brush gets over these steps is one of the noises when the electric motor is driven. Then, as described above, the driving sound of the electric motor using the brush 10 in which one edge portion 10d of the sliding contact surface 10b is curved and the sliding contact width changes in the rotation direction of the motor shaft. However, there is a need for improvement in today's world where there is a large demand for quietness. Incidentally, when the driving sound when the brush 10 is used is analyzed by, for example, a sound analyzer, it is observed that the high frequency component is large and the sound pressure is high. Moreover, the sound at this time is as shown in FIG.
As shown in (B), it was found that the high-frequency component was large, a wide range of sounds from low to high were simultaneously produced, and the sliding contact sound was sensuously increased. As shown in FIG. 8A, when the sliding contact surface 10b rotates relative to the commutator in the direction of arrow A and makes sliding contact, the curved edge portion 1 of the sliding contact surface 10b is described.
Since each part of 0d repeatedly crosses the commutator step, it is presumed that the sound over the step at this time is generated simultaneously as sliding sounds with different wavelengths. There was a problem to be solved by the invention.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in order to solve these problems, and it is an outer periphery of a commutator integrally fitted on a motor shaft. In the electric motor in which the inner diameter side surface of the brush biased from the outer diameter side is in sliding contact with the surface in an elastically-pressed manner,
In forming the inner diameter side surface of the brush with a sliding contact surface formed in a concave curved surface along the commutator outer peripheral surface and an inclined surface inclined so as to be separated from the commutator outer peripheral surface, the inclined surface is formed into a sliding contact surface. It is formed to have a concave curved surface that matches the curved surface of (1) so that the sliding contact width of the sliding contact surface in the motor axial direction is maintained substantially constant. And by doing in this way, the sliding contact noise with a commutator can be made quiet and it can be set as an electric motor of low noise. Further, the present invention is
On the outer peripheral surface of the commutator that is integrally fitted to the motor shaft,
In an electric motor in which an inner diameter side surface of a brush urged from the outer diameter side slidably contacts, a step of forming a curved contact surface along the inner diameter side surface of the brush and a commutator outer circumference And a step of forming an inclined surface inclined so as to separate from the surface into a concave curved surface that matches the curved surface of the sliding contact surface. And by doing in this way, the sliding contact noise with a commutator can be made quiet and it can be set as an electric motor of low noise. In this case, the concave curved surface of the inclined surface and the concave curved surface of the sliding contact surface of the present invention can be formed to have the same curvature.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to FIG.
~ It demonstrates based on the drawing of FIG. In the drawings, reference numeral 1 denotes a drive unit for constructing an electric power steering apparatus, and a casing 2 of the drive unit 1 has a cylindrical bottomed bottom surface on which a bearing portion 2a is formed. A base end portion 4a of an armature shaft (a motor shaft, which corresponds to the drive shaft of the present invention) 4 that constitutes the armature 3 is rotatably supported via a bearing 2b. On the other hand, the front end portion 4b of the armature shaft 4 projects from the front end side surface of the bracket 5 arranged so as to cover the opening of the casing 4, and the base end side portion of the front end portion 4b is opened in the bracket 5. Bearing 5b in bearing boss hole 5a
It is rotatably supported via.

Further, 6 is a commutator externally fitted and fixed to the tip side portion of the armature shaft 4. The commutator 6 has a plurality of axially long segments 6a which are insulated from each other on a peripheral surface thereof with a predetermined gap. It is formed so that it is buried in the state of being buried. On the other hand, the bracket 5 supports a holder stay 7, and the holder stay 7 is formed with a pair of brush holders 7a in the circumferential direction.
The brushes 8 are housed in the brush holders 7a so as to be retractable and retractable, and the ammunition 9 is housed between the outer diameter side surface 8a of the brush 8 and the outer diameter side piece 7b of the brush holder 7a. Has been done. by this,
The brush 8 is urged toward the inner diameter side by the urging force of the ammunition machine 9, and the inner diameter side surface 8b is set so as to elastically slidably contact the outer peripheral surface of the commutator 6. A permanent magnet 2c is fixed to the inner peripheral surface of the casing 2, and an external power source is supplied to the armature coil 3a of the armature 3 via the brush 8 and the commutator 6,
The armature 3 is set so as to rotate integrally with the armature shaft 4.

Now, the brush 8 has a pigtail 8 from a base end side surface (in this embodiment, a bottom surface side of the casing 2).
c is extended and is set so as to be connected to an external power source through the pigtail 8c. And brush 8
A sliding surface 8d, which is a concave curved surface having a curvature similar to that of the outer peripheral surface, is formed along the outer peripheral surface of the commutator 6 at the tip side portion of the inner diameter side surface of the sliding surface 8d. On the end side, an inclined surface 8e is formed, which is separated from the outer peripheral surface of the commutator 6 toward the base end side.

The inclined surface 8e has a linear inclination in a side view with reference to the inclined surface 8e, but is formed in a curved surface having a concave central portion in a front view. It is set to be similar to the curvature of the curved surface of the sliding contact surface 8d. At this time, the inclined surface 8e is formed into a curved surface such that the shape of the inclined surface 8e when it is cross-sectioned with an arbitrary surface orthogonal to the direction of the motor shaft 4 is concave at any place (see FIG. 4 (E)), One edge 8f of the slidable contact surface formed by the intersection of the inclined surface 8e and the slidable contact surface 8d has a linear shape, and as shown in FIG. When the front surface of the contact surface 8d is viewed in a rectangular shape,
The sliding contact width S facing the direction of the motor shaft 4 is set to be substantially constant. As a result, when the sliding contact surface 8d rotates relatively in the sliding contact shape in the arrow A direction on the outer peripheral surface of the commutator 6 in which a step is formed between the adjacent segments 6a, the sliding contact surface 8d is As a result of sliding contact with the outer peripheral surface of the commutator 6 at a substantially constant position, only one portion H, which is the tip of the sliding contact surface 8d in the rotational direction of the edge 8f of the sliding contact surface 8d, crosses over the step portion. It is set so that the sound generated thereby can be reduced and the wavelength of the generated sound can be made uniform because the sliding contact width S is constant, so that a quiet driving sound can be obtained. Incidentally, the drive sound of the drive unit 1 including the brush 8 formed according to the present embodiment is shown in FIG.
As shown in FIG. 6A, according to this, the range of high frequency components is reduced as compared with the driving sound when the conventional brush 10 shown in FIG. It was observed. In addition, it was confirmed by observation with a sound analyzer that the high-frequency component was reduced and the sound pressure was lowered, as compared with the conventional brush using the sliding contact width changing.

In the embodiment of the present invention configured as described above, when the drive unit 1 constituting the power steering is driven, the brush 8 has the sliding surface 8d formed on the inner diameter side surface on the commutator 6 side. The inclined surface 8e formed so as to be separated from the outer peripheral surface of the commutator 6 is a concave curved surface that matches the concave curved surface of the sliding surface 8d, and the edge portion 8f where the sliding surface 8d and the inclined surface 8e intersect is formed. The sliding width S, which is substantially linear and faces the axial direction of the sliding surface 8d, is substantially constant in the circumferential direction. For this reason, only the portion H that contacts the step formed between the segments 6a on the outer periphery of the commutator 6 is the front side portion H of the edge portion 8f in the rotation direction, and the sound over the step is reduced, resulting in low noise. In addition, it is possible to prevent the sounds of different wavelengths from being produced at the same time, the width of the sounds is reduced, and it is possible to avoid the sensory noise. Therefore, the quiet drive unit 1 can be obtained. it can.

Furthermore, in this case, the inclined surface 8e of the brush is used.
Is formed into a curved surface such that the shape of the cross section taken along an arbitrary plane orthogonal to the direction of the motor shaft 4 is concave at any position. Therefore, assuming that the brush sliding contact surface 8d is worn for a long period of time, the sliding contact width of the sliding contact surface 8e changes from the initial use, but the sliding width dimension is constant in the circumferential direction. The state of the noise is maintained as it is, and the noise can be kept low for a long time.
Furthermore, since the inclined surface 8e of the brush 8 is simply formed as a concave curved surface, it is possible to easily reduce the noise without increasing the number of parts when implementing the noise reduction.

Of course, the present invention is not limited to the above-mentioned embodiment, and a plurality of sliding surfaces can be formed in the motor axial direction on the inner diameter side surface of the brush. By making the inclined surface that is separated from the commutator formed on the concave curved surface that matches the concave curved surface of the sliding surface, the sliding width of the sliding surface can be made constant. The effect can be obtained.

[Brief description of drawings]

FIG. 1 is a side view of a drive unit that constitutes a power steering device.

FIG. 2 is a partial cross-sectional side view of a drive unit that constitutes the power steering device.

FIG. 3 is a front view of a drive unit that constitutes the power steering device.

FIG. 4 (A), (B), (C), (D), (E)
Are the perspective view, top view, side view, front view, and
It is a XX sectional view of FIG.

5 (A) and 5 (B) are pattern diagrams for explaining the action in relative rotation between the commutator outer peripheral surface and the sliding contact surface.

6A and 6B are graphs showing driving sounds of a driving unit using a brush according to the present embodiment and graphs showing driving sounds of a driving unit using a brush according to a conventional example, respectively. Is.

7 (A), (B), (C), (D), (E)
Are perspective views, plan views, side views, and
It is a front view and the XX sectional view of FIG. 7 (B).

FIG. 8A and FIG. 8B are pattern diagrams for explaining the action in relative rotation between the commutator outer peripheral surface and the conventional brush sliding contact surface.

[Explanation of symbols]

1 drive unit 2 casing 5 bracket 6 commutator 6a segment 7 Holder stay 8 brushes 8b Inner diameter side 8d sliding surface 8e inclined surface 9 ammo

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Hagiwara             Gunma prefecture Kiryu city Hirosawa town             Mitsuba Co., Ltd. F-term (reference) 5H613 AA01 BB14 BB15 BB16 BB22                       GA04 GB09 QQ05 SS05

Claims (3)

[Claims] 1. An electric motor in which an inner diameter side surface of a brush urged from the outer diameter side slidably contacts an outer peripheral surface of a commutator externally fitted to a motor shaft in an elastic pressure manner. In forming a sliding contact surface formed in a concave curved surface along the commutator outer peripheral surface and an inclined surface inclined so as to be separated from the commutator outer peripheral surface, the inclined surface is formed into a concave shape matching the curved surface of the sliding contact surface. Form on a curved surface,
A brush in an electric motor in which the sliding contact width of the sliding contact surface in the motor axial direction is maintained substantially constant. 2. An electric motor in which an inner diameter side surface of a brush urged from the outer diameter side is in sliding contact with the outer peripheral surface of a commutator integrally fitted on the motor shaft in an elastically pressing manner. A step of forming a curved sliding contact surface along the commutator outer peripheral surface, and a step of forming an inclined surface inclined so as to separate from the commutator outer peripheral surface into a concave curved surface matching the curved surface of the sliding contact surface. A method for manufacturing a brush in an electric motor, characterized in that 3. The brush in an electric motor according to claim 1, wherein the concave curved surface of the inclined surface and the concave curved surface of the sliding contact surface are formed to have the same curvature, or a manufacturing method thereof.