JPS5819141A - Bracket for miniature dc motor - Google Patents

Abstract

PURPOSE:To improve the electric noise performance of a DC motor by burying a magnetic metal plate in a bracket, mounting a terminal board on the surface and bringing a terminal passing through the bracket in contact with a magnetic metal plate, thereby facilitating an assembling work. CONSTITUTION:A bracket plate 15 made of a magnetic metal plate is buried in synthetic resin to form an end bracket 11. A terminal board 16 is mounted on the surface of the bracket 11, a brush 20 is secured, a terminal 17 is provided through the bracket 11 from the board 16, and is contacted with the plate 15 via a swelled part 19 formed at the intermediate of the terminal 17. Since the terminal and the end bracket are integrated in this manner, the assembling work can be facilitated, and since the plate 15 may be grounded, the electric noise performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bracket for a small DC motor, in which a terminal plate to which a brush is connected and a bracket plate made of a magnetic metal plate are integrally molded from synthetic resin, and The terminal board and the bracket board are brought into reliable contact with each other to improve bracket assembly accuracy and electrical noise performance, and to reduce costs.

A conventional small DC motor bracket consists of a composite assembly involving several types of parts, as shown in FIG. That is, the central recess 21 of the bracket metal fitting 1 made of an iron plate
C. Insert the resin thrust plate 3 and bearing 4 for receiving the rotating shaft, and connect the bracket 3 to the plate spring part 8 integrally provided on the insulating plate 7 to which the brush 6 and brush terminal plate 6 are attached. The bearing 4 is held between the brushes 6 and 6. A brush terminal plate 6 and an insulating plate 7 are fixed to the bracket 3 with screws 9. In addition, in order to ground the back electromotive force flowing through the brush 6, the terminal portion 10 of the terminal plate 6, which passes through the insulating plate 7 and the bracket metal fitting 1, is bent in the direction of arrow A and brought into contact with the bracket metal fitting 1, so that it can be electrically welded. and is fixed to the bracket metal fitting 1.

Figure 3 shows the electrical noise level when the terminal board 6 is not grounded and when it is grounded.A is the case where the terminal board 6 is not grounded, and the pulse voltage reaches 6V at the peak, but when it is grounded, the pulse voltage reaches 2V. The effect is more than halved.

Conventionally, this grounding is performed by electrical welding, as described above, but even with electrical welding, variations in welding strength can be considered. Its electrical conductivity is more effective than screws and grommets, but it is not perfect.In particular, stable conductivity is required to prevent electrical noise, so variations in electrical welding are caused by electrical noise. There were also variations in characteristics. Furthermore, due to the variations, electrical welding work was difficult and work efficiency was extremely poor.

The present invention has been made in view of the above-mentioned conventional drawbacks, and one embodiment of the present invention will be described below with reference to FIG. 3. In the figure, 11 is a disc-shaped end bracket made of synthetic resin.
A recess 13 for housing the bearing 12 is formed in the center, and a plurality of protrusions 4 are integrally formed in the four parts 13 to constitute a bearing holding part. Reference numeral 16 designates a ring-shaped bracket plate made of a magnetic metal plate that is resin-molded integrally with the end bracket 11, with its inner and outer circumferential ends exposed and the rest buried in the end bracket. Reference numeral 16 designates a brush terminal plate which is molded integrally with the end bracket 11 by resin molding, and is fixed to the surface of the end bracket 11 so that its upper surface is exposed. 17 is a terminal portion of the brush terminal plate 16 that passes through the end bracket 11, and a through hole 18 provided in the bracket plate 16 is located in the end bracket.
A bulging part 19 is integrally provided to press into contact with the terminal.In this case, the appropriate press-fitting clearance is 20 to 100μ, and after resin molding, the terminal part will not move and will always be in good condition. The terminal portion and the bracket plate 16 come into contact with each other. The brush 2o is placed in a position-controlled manner on the brush terminal plate H, and is electrically attached to the brush terminal plate 16 by spot welding or the like. Also, bearing 1
2 is held by the end bracket 11 by the elasticity of the protrusion 14 by simply inserting it into the four parts 12 of the end bracket 11.

According to the above configuration, there is no need to process the conventional thrust plate 3 and insulating plate 7 at the same time using resin, and the parts to be assembled as a bracket assembly are the end bracket 11, the bearing 12, and so on. Since there are three types of brushes 20, the accuracy of bracket assembly is significantly improved and the number of man-hours for assembling the bracket is reduced. In addition, stable contact between the terminal portion 17 of the terminal plate 16 and the bracket plate 16 can be ensured without using electrical welding, and the terminal plate 16 is reliably grounded by the bracket plate 15, resulting in improved electrical noise performance. You can also plan.

As is clear from the above description, according to the present invention, since the bracket plate and the terminal plate are integrally molded with the end bracket, the assembly accuracy of the parts is improved, a good rectifying effect is obtained, and the assembly is easy. 9. It is also possible to reduce costs. In addition, since the terminal board is grounded to the bracket board, electrical noise performance is improved1, and there is no need to use electrical welding for this connection.Moreover, the terminal part of the terminal board is held by the end bracket, This has the effect that the contact with the bracket plate is always stable.

[Brief explanation of the drawing]

FIG. 1a is a cross-sectional view of a bracket assembly for a conventional small DC motor, FIG. 1 is an enlarged cross-sectional view of the same essential parts, and FIG. Figure 2 is an enlarged sectional view of the same essential part, and Figures 3a and 3b are waveform diagrams that compare and show the level of electrical noise depending on whether or not the brush terminal plate is grounded. 11... End bracket, 12...
Bearing, 13... Recess, 16... Bracket plate, 16... Terminal plate, 17... Terminal portion, 18... Through hole , 19... bulge, 20... brush. Name of agent: Patent attorney Toshio Nakao and 1 other person11
Figure 1 (α) Figure 2

Claims (1)

[Claims] A bracket plate made of a magnetic metal plate is embedded in a synthetic resin end bracket that is resin molded, and a terminal plate is integrally fixed so as to be located on the surface of this end bracket. A bracket for a shed DC motor, wherein the plate is provided with a terminal portion that penetrates the end bracket, and a portion of the terminal portion located in the end bracket is formed with a bulge portion that comes into pressure contact with a through hole provided in the bracket plate. .