JPH08205481A - Brush for dc motor - Google Patents

Abstract

PURPOSE: To enhance the efficiency of motor by improving poor commutation at initial conditions. CONSTITUTION: When a commutotor 1 is rotating, a brush 2 inserted idly into a brush holder 3 is stabilized in the brush holder 3 while being displaced by the sliding friction based on the rotation of the commutator 1. The brush 2 has such sliding face as a commutator segment has a width W2 of semicircular surface at the sliding part with respect to the width W1 of commutator segment at initial conditions. Furthermore, noncontact faces 2a are provided on the opposite sides and the brush 2 can slide on a commutator segment on the center line or across the adjacent commutator segments. With such arrangement, the commutation is enhanced and the characteristics are stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor, and more particularly to the shape of an initial sliding surface of a brush.

[0002]

2. Description of the Related Art A conventional brush shape is disclosed in
Some are described in Japanese Patent Publication No. 5-328672. This has a radius R with a radius R of a semicircular surface slidingly contacting in the circumferential direction as a center point at a position at least longer than the radius of the commutator, and the brush is pressed against the inner wall of the brush holder by sliding friction when the commutator rotates. With the brush having a shape such that the arc of the commutator passes through the center of the brush in the width direction, the characteristic fluctuation and the deterioration of noise are prevented.

[0003]

In the prior art, the brush is effective only in the structure in which the inner wall of the brush holder is completely pressed by the sliding friction when the commutator is rotated, and the brush is inclined in the brush holder. However, the characteristics fluctuation was not taken into consideration.

It is an object of the present invention to improve the efficiency of a DC motor even in a structure in which it is completely pressed against the inner wall of the brush retainer or in a structure in which the brush is inclined, by preventing characteristic fluctuations due to deterioration of rectification caused by uneven contact of the brush. It is in.

[0005]

[Means for Solving the Problems] In order to solve the problems,
In the present invention, regardless of the holding state in the brush retainer in the initial state, the sliding surface of the brush is a semi-circular surface that is in sliding contact with the commutator piece on the center line in the circumferential direction, and further has non-contact surfaces on both sides. Set up.

[0006]

The brush is completely pressed in the brush holder by the sliding friction of the brush when the commutator rotates. Or the brush tilts. At this time, ideally, if the brush sliding surface comes into contact with all of the opposing commutator pieces, a good commutation state can be obtained and characteristic fluctuations do not occur, but in reality, the sliding contact will occur in a tilted state, so that the centerline By providing a semi-circular surface that is in sliding contact with the commutator piece, the rectifying function is excellent and the characteristic variation is small.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is an embodiment of the present brush, showing a commutator and a fragmentary cross section showing the brush, and FIG. 2 is an enlarged view. Reference numeral 1 denotes a commutator in which electric power is supplied to the armature from a power source, 2 is a brush for supplying electric power to the commutator 1, 3 is a brush holder for holding the brush 2, and the brush 2 is inclined with respect to the brush holder 3. Sliding at contact point 4 in the case diagram.
In FIG. 4, the brush 2 slides at the contact point 4 when it is pressed against the inner wall of the brush holder 3. The width W1 of the brush 2 is usually determined from the relationship with the rectifying band, and has a structure that covers two or more commutator pieces. Initially, the contact point 4 of the conventional brush is in sliding contact with the commutator piece 12 on the front side in the rotation direction with respect to the commutator piece 11 on the center line as shown in FIGS. 3 and 5, so that the brush is moved in the rotation direction. The same result is obtained and rectification failure occurs,
Characteristic fluctuation occurs. Therefore, the width W2 of the semicircular surface of the sliding portion is set to the width W3 of the commutator piece with respect to the width W1 of the commutator piece, and the non-contact surfaces 2a are further provided on both sides thereof, and the brush 2 is loosely inserted into the brush holder 3. Brush holder 3 based on rotation of commutator 1
1 and 2 in the state of FIG. 1, FIG. 2 and FIG.
When the commutator 1 rotates, the brush 2 stabilizes in a tilted state in the brush holder 3 due to sliding friction. Since the brush 2 is provided with the semi-circular surface width W2 and the non-contact surface 2a width, the brush 2 can be brought into sliding contact with the commutator piece on the center line, a favorable rectifying action can be obtained, and the characteristics are stable. In FIG. 4, when the commutator 1 rotates, the brush 2 is stabilized in a state of being pressed against the inner wall of the brush holder 3 by sliding friction. Since the brush 2 is provided with the semi-circular surface width W2 and the non-contact surface 2a width, similar to the above,
The characteristics are stable due to good rectification. FIG. 6 is a view showing a case where the semicircular surface width W2 extends over the adjacent commutator piece,
In this case, since the commutator piece 11 on the center line and the commutator piece 12 on the front side in the rotation direction are in sliding contact with each other at two points, deterioration of the rectifying action can be prevented and the same effect as described above can be obtained. As described above, the operation is performed in the initial state, and the brush 2 eventually comes into sliding contact with the entire surface, so that a stable DC motor can be obtained without fluctuation in characteristics from the initial state.

[0008]

According to the present invention, it is possible to prevent the output performance from deteriorating due to defective rectification in the initial state and improve the efficiency.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a sliding contact between a brush and a commutator in an inclined state in a brush holder according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a sliding contact between a brush and a commutator in an inclined state in a brush holder according to an embodiment of the present invention.

FIG. 3 is a partial cross-sectional view showing sliding contact between a brush and a commutator in an inclined state in a conventional brush holder.

FIG. 4 is a partial cross-sectional view showing a sliding contact between a brush and a commutator in a state of being pressed in the brush holder according to the embodiment of the present invention.

FIG. 5 is a partial cross-sectional view showing a sliding contact between a brush and a commutator in a state of being pressed in a conventional brush holder.

FIG. 6 is a partial cross-sectional view showing a sliding contact between a brush and a commutator in a state where the brush straddles an adjacent commutator piece according to an embodiment of the present invention.

[Explanation of reference numerals] 1 ... commutator, 2 ... brush, 3 ... brush retainer, 4 ... contact point, 11 ... commutator piece on center line, 12 ... commutator piece in front of rotation direction.

Front Page Continuation (72) Inventor, Hisao Tomite, No. 3085, Nishigouchi, Higashiishikawa, Hitachinaka, Ibaraki 5 Hitachi Car Electronics Co., Ltd.

Claims (2)

[Claims] 1. A brush, which is loosely inserted in a brush holder slidably contacting a commutator of the armature for supplying electric power from a power source to the armature, has a sliding surface in a circumferential center in an initial state. A brush for a DC electric motor, characterized in that a semicircular surface that is in sliding contact with a commutator piece on the wire is provided, and further non-contact surfaces are provided on both sides. 2. A semicircular surface which is in sliding contact with the commutator piece on the center line in the circumferential direction and the two commutator pieces at the inlet in the rotational direction in the initial state, and further has no contact on both sides. DC motor brush with a surface.