JPH0923617A - Rotation detector for motor - Google Patents

Abstract

PURPOSE: To obtain a rotation detector for motor where each commutator is provided with an extension for detecting the rotation and an auxiliary brush is not mounted between adjacent extensions. CONSTITUTION: The commutator segment 4 of a commutator 3 is provided with a narrow extension 4b being cut on the opposite sides in the circumferential direction with respect to the body part such that the interval of extension 4b is longer than the circumferential dimension of an auxiliary brush.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation detecting device in a motor for detecting the rotation of an armature core provided in the motor.

[0002]

2. Description of the Related Art In general,
Some motors are designed to detect the rotation of the armature core, and as a detection means therefor, there is disclosed in Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Laid-Open No. 245454, a commutator provided on a commutator is provided with a long extension, and the extension is detected by an auxiliary brush to detect the rotation of the armature core. .

In this case, the detection accuracy is
The higher the number of commutator pieces on which the extension parts are formed, the higher the detection accuracy becomes. The extension parts are formed on all the commutator pieces and each extension part is detected.
However, in such a case, since the interval between the adjacent commutator pieces is narrower than the width of the auxiliary brush, the auxiliary brush straddles both the adjacent commutator piece extensions, and the sliding contact occurs simultaneously. In the sliding contact state, there is a problem that one of the armature coils is short-circuited, the driving efficiency is lowered, and the detection signal is disturbed due to the short-circuit.

[0004]

SUMMARY OF THE INVENTION The present invention was devised with the object of providing a rotation detecting device for a motor capable of eliminating these drawbacks in view of the above-mentioned circumstances, and an armature core In providing the extension part for the auxiliary brush for rotation detection to be slidably contacting the commutator piece of the commutator provided in, the extension part has a gap between the extension parts of the adjacent commutator pieces in the circumferential direction of the auxiliary brush. It is characterized in that it is cut out so as to be larger than the dimension of.

According to the present invention, according to the present invention, all commutators are provided with the extension portions for rotation detection, but the auxiliary brushes do not straddle the extension portions adjacent to each other. It was done.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 is an armature core of a motor with a rotation detection function, and a commutator 3 is integrally provided on a core shaft 2 of the armature core 1.
The present invention is applied to the commutator piece 4 that constitutes the commutator 3. That is, the commutator piece 4 has the columnar insulating base material 5
The brush 6 for driving the motor is slidably embedded in the outer peripheral portion of the motor with a gap A, and the commutator piece 4 is used for detecting rotation from the main body portion 4a with which the brush 6 for driving the motor slides. An extension portion 4b for sliding contact with the auxiliary brush 7 is integrally formed in a narrow state. That is, the extension portion 4b is the main body portion 4
Both sides in the circumferential direction are notched with respect to a and are narrow, and the gap B between the extension portions 4b of the adjacent commutator pieces 4 is larger than the dimension C of the auxiliary brush 7 in the circumferential direction. (B>C> A), so that the auxiliary brush 7 is designed so as not to be in sliding contact with a pair of adjacent extension portions 4b at the same time. The auxiliary brush 7 is connected to a rotation detecting circuit 8 as shown in FIG. 4, and detects the rotation of the armature core 1.

In the embodiment of the present invention configured as described above, the rotation detection of the armature core 1 is detected by the auxiliary brush 7.
Is carried out every time it makes sliding contact with the extension portion 4b. In this case,
The extension portion 4b is narrower than the main body portion 4a, and the gap B between the adjacent extension portions 4b is larger than the dimension C of the auxiliary brush 7 in the circumferential direction. 4b
Never slide in contact with one another at the same time. As a result, although all the commutator pieces 4 can perform rotation detection with high accuracy, the auxiliary brush 7 is simultaneously brought into sliding contact with the adjacent extension portion 4b, and one of the armature coils is short-circuited. Drive efficiency is not lowered, and the detection signal is not disturbed by the chattering phenomenon due to the short circuit, and rotation is detected as a regular rectangular wave.

It should be noted that the present invention is not limited to the above-described embodiment, but the method for forming the narrow extension is not limited to the one in which both sides in the circumferential direction of the main body are cut out. Instead, as in the second embodiment shown in FIG. 5, it can be formed by notching only one side in the circumferential direction.

[0009]

In summary, since the present invention is constructed as described above, the extension portions of the commutator piece are notched so that the gap between the extension portions is larger than the circumferential size of the auxiliary brush. Therefore, unlike the conventional one, adjacent commutator pieces do not come into sliding contact with each other, and as a result, due to the short circuit of the armature coil while providing the extension part for rotation detection on all the commutator pieces. It is possible to avoid a decrease in drive efficiency and a disturbance in the detection signal, and it is possible to perform rotation detection with higher accuracy.

[Brief description of drawings]

FIG. 1 is a side sectional view of a motor.

FIG. 2 is a side view of a main part of a commutator.

FIG. 3 is a cross-sectional perspective view of essential parts of the commutator.

FIG. 4 is a rotation detection circuit diagram.

FIG. 5 is a side view of an essential part showing a second embodiment.

[Explanation of symbols]

 1 Armature Core 2 Armature Core Shaft 3 Commutator 4 Commutator Piece 4a Body 4b Extension 6 Brush 7 Auxiliary Brush

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 12, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

Claims (1)

[Claims] 1. A commutator piece of a commutator provided in an armature core is provided with an extension portion for sliding contact of an auxiliary brush for rotation detection, wherein the extension portion is a gap between extension portions of adjacent commutator pieces. A rotation detecting device for a motor, characterized in that it is cut out so as to be larger than the size of the auxiliary brush in the circumferential direction.