JPH01311848A - Brush structure in rotary electronic machine - Google Patents

Abstract

PURPOSE:To detect the state of the abrasion of a brush by forming a broad section in order to change sliding contacting length of the brush in the direction of rotation of a commutator when the brush is worn up to a specified position. CONSTITUTION:A brush 7 slid and contacted to a commutator 2 in an elastic pressing manner wears broad 7b on use in a sliding contacting surface and its sliding contacting length in the direction of rotation of the commutator 2 lengthens. Consequently, the stroke of a neutral state in which the brush 7 is slid and contacted between the mutual adjacent segments of the commutator 2 is lengthened, and the center of the position of the sliding an contacting of the brush 7 is displaced at a certain angle from the center of a magnet. The change can be detected by a current detector and revolution detector; therefore, the small residue of the brush 7 can be identified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a brush structure for a rotating electrical machine that slides into pressure-like contact with a commutator.

[Prior art and problems to be solved by the invention] Generally,
This seed brush is adapted to come into sliding contact with the commutator in a pressing manner under the urging force of the bullet. By the way, brushes gradually wear out due to sliding contact with the commutator, but in the past, it was not possible to know the wear status of the brush, so people used to continue using the brush without realizing that it had worn to the limit. If you do so, the rotary electric machine may suddenly stop working, or the commutator may be damaged, and in this case, the entire rotary electric machine must be replaced.

[Means to solve the problem]

In view of the above-mentioned circumstances, the present invention was devised for the purpose of providing a brush structure for a rotating electrical machine that can eliminate these drawbacks. The present invention is characterized in that a wide portion is formed to change the sliding length of the brush in the direction of rotation of the commutator when the brush is worn to a predetermined position.

According to the present invention, with this configuration, it is possible to detect when the brush has worn down to a predetermined position.

〔Example〕

Next, one embodiment of the present invention will be described based on the drawings. In the drawings, 1 is an electric motor, and the motor 1 includes:
The rotor 3 with the commutator 2, the magnet 5 fixed to the case 4, the brush 7 fitted into the brush holder 6 so as to be retractable, etc. are all the same as before.

The brush 7 protrudes from the brush holder 6 due to the biasing force of the bullet 8, and the inner end surface of the protruding brush 7 is connected to the commutator 2.
The brush 7 is designed to come into sliding contact with the commutator 2 in an elastic manner, but the side to which the pigtail 9 is connected is widened in the direction of rotation of the commutator 2. In other words, the brush 7 initially has a small sliding contact area with the commutator 2 because the tip portion 7a is not wide, but after being worn by an amount of I due to use, it becomes larger in the rotational direction due to the wide portion 7b. It is configured so that

In the embodiment of the present invention configured as described above, the brush 7 that slides in pressure-like contact with the commutator 2 wears out due to use, and the sliding contact surface becomes a wide part 7b, so that the length of sliding contact in the direction of rotation of the commutator 2 is long. Become.

By the way, for the motor 1, the relationship between the load current ■ and the output torque T, and the relationship between the load current I- and the rotational speed N are generally shown as the characteristic curves of the X-line and Y-line in FIG. However, in such a motor 1, if the sliding length of the brush 7 in the direction of rotation of the commutator 2 becomes longer as described above, the stroke in the neutral state where the brush 7 slides into adjacent segments of the commutator 2 becomes longer. Naru, and brush 7
The center of the sliding contact position is angularly shifted from the center of the magnet, and therefore the characteristic curve is
, change as shown by the line, and be identified as d. Therefore, by detecting this change using, for example, a current detector or a rotation speed detector, it can be determined that the remaining amount of the brush 7 is small.

In this way, according to the present invention, it is possible to know when the brush 7 has reached its wear limit, and to replace it at an appropriate time. Therefore, it is possible to prevent the motor 1 from suddenly stopping due to wear and tear of the brush 7, and also to prevent damage to the commutator 2, thereby greatly extending the life of the motor 1. can.

Furthermore, in this case, when the brush 7 approaches its wear limit, the wide portion 7b comes into sliding contact with the brush 7, which slows down the wear rate and helps extend the life of the brush 7 itself, thereby preventing the brush 7 from missing its replacement time. is effectively prevented.

It should be noted that the present invention is of course not limited to the above-mentioned embodiments, and the shape of the brush may be as shown in FIGS. It is sufficient if the length can be changed. Furthermore, in consideration of fitting into the brush holder 6, the part where the pigtail 9 is implanted is made into a wide part 7b as shown in FIG. good.

[Effect]

In summary, since the present invention is constructed as described above, when the brush that is in sliding contact with the commutator in an elastic manner wears out due to use and reaches the wide part, the length of the brush in sliding contact with the commutator in the rotating direction changes. , This changes the characteristics of the rotating electrical machine. Therefore, by detecting this change in characteristics, it is possible to know when the brush has worn out and it is time to replace it, and as a result, it is possible to simplify the maintenance management of the rotating electrical machine. It is possible to effectively avoid this and ensure highly reliable motor drive.

[Brief explanation of the drawing]

The drawings show an embodiment of the brush structure in a rotating electrical machine according to the present invention, in which FIG. 1 is a cross-sectional view of the motor, FIG. 2 is a perspective view of the brush, and FIG. 3 A, B, and C are views of the brush. FIG. 4, which is a perspective view of the brush showing the other side, is a graph showing the characteristics of the motor. In the figure, 2 is a commutator, 7 is a brush, and 7b is a wide part. Fig. 3 A B Fig. 4

Claims (1)

[Claims] A brush structure for a rotating electric machine, characterized in that a wide portion is formed on a brush that slides in an elastic manner on a commutator in order to change the sliding length of the brush in the commutator rotation direction when the brush wears to a predetermined position.