JPS5855629B2 - Brush Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brush device such as a DC motor.

As shown in FIG. 1, a conventional brush device for a DC motor includes a brush B having a sliding contact 2 made of a resistive material fixed to one end of a metal plate 1, and a sliding contact 2 attached to a segment g12g2 of a commutator G. The sliding contacts 2 were arranged so as to be in contact with each other, and power was supplied from the back surface of the sliding contact 2 through the metal plate 1.

Therefore, the resistance value between the metal plate 1 and the sliding surface of the sliding contact 2 is uniform at each point on the sliding surface, and the segment g1 t
The potential of the part in contact with g2 is f and the current density is uniform, and since the resistance values of parts a and b of sliding contact 2 are the same, current flows in part b with the same current density as part a, When part b of brush B separates from segment g1, coil L
This has the disadvantage that a large surge voltage is generated due to the cutting of the brush B, and the resulting sparks damage the brush B.

In order to overcome this drawback, a commutator structure was proposed in which a resistive material R is inserted near the line (sring) 1 between segments Fgt to g3, as shown in Figure 2, so that the current is gradually cut off when the coil L is cut. It was done.

However, since the materials of the resistance material R and the segments g1 to g3 are different, a difference in wear occurs, which increases the occurrence of chattering of the flange B, and furthermore, the wear particles of the segments g1 to g3 get on the resistance material R, and the initial effect is not achieved. There were various drawbacks such as the fact that it was difficult to bond the segments g1 to g3 and the resistance material R, and that processing was difficult.

It is therefore an object of the invention to provide a brush device that is able to overcome the aforementioned problems.

FIG. 3 shows an embodiment in which the present invention is applied to a flat plate commutator, in which the brush B has a sliding plate made of a resistive material such as carbon or a metal having a resistance value at one end of the = side surface of the insulating resin plate 11. A moving contact is provided.

A conductive layer e is formed on the insulating resin plate 11.
Segment g12g2 of commutator G with one end as a sliding contact
A power source E is connected to the other end of the conductive layer e.

Therefore, the resistance value between the conductive layer e and the surface 12 of the sliding contact increases as the surface 12 moves forward in the rotational direction of the commutator G.

When power is supplied to the sliding contact from the power source E, the current density of the current entering from the conductive layer e and exiting from the surface 12 of the sliding contact is
2, the current density changes with respect to the rotational direction of the commutator G as shown in FIG. is the segment g in the current density distribution shown in Figure 4.
1, when the commutator G moves to the left in the diagram and the sliding contact shorts the segment l'' gl + g2, the current in the segment Fgt is smaller than that of the conventional example,
Conversely, a larger current flows through segment g2 than in the conventional example.

When the sliding contact leaves the segment g1, that is, when the coil L is disconnected, a large current flows in the section a and the current in the section b becomes small, so that no large surge voltage is generated.

When the sliding contact is on segment g2, power is supplied with the current distribution shown in FIG. 4 in the same way as when it is on segment g1.

FIG. 5 shows another embodiment in which the present invention is applied to a cylindrical commutator, in which an L-shaped conductive layer e is formed on the upper surface of a columnar sliding contact made of a resistive material via an insulating material 14. Sliding surface 1
A brush B disposed in contact with a side surface 13 orthogonal to the brush B is housed in a cylindrical holder H so as to be movable up and down, and is arranged so that the sliding surface 12 is brought into contact with the segments g1 + g2 of the commutator G by means of a spring 15. This embodiment is designed to perform the same function as the above embodiment.

As described above, according to the present invention, the current flowing through the sliding contact of the brush when the coil is cut is reduced, so the generation of surge voltage is small, the generation of sparks is reduced, and radio wave interference can be prevented. This has the effect of preventing damage to the brush and segments and improving the life of the brush.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams of a conventional example, Figure 3 is a schematic diagram showing an embodiment of the present invention, Figure 4 is a current density distribution diagram of a sliding contact, and Figure 5 is a diagram of the current density distribution of a sliding contact. It is a schematic diagram showing another example. B... Brush, D... Sliding contact, e.
... Conductive layer, G ... Commutator, g18g2
...Segment, L...Coil.

Claims (1)

[Claims] 1. A brush with a conductive layer for power supply provided on a surface perpendicular to the surface that slides on the commutator segment of a sliding contact made of a resistive material is commutated so that the conductive layer for power supply is on the rear side in the direction of rotation of the commutator. A brush device characterized in that it is arranged in contact with a child.