JP3377360B2 - Power supply for small DC motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a power supply device for a small direct current motor, and more particularly, it is used as a silent reception notification means of a wireless communication device, and is a thin cylinder type which does not allow a large deflection of a brush. It is suitable for use in a motor.

[0002]

2. Description of the Related Art A conventional thin cylinder type motor, for example, is shown in FIG. 4 of Japanese Patent Application No. 4-176110.

[0003]

In the conventional power feeding device having the above-mentioned structure, since the motor main body is a thin cylinder, the amount of deflection of the brush slidably contacting the cylindrical commutator cannot be made large, and the middle portion is bent to form an L shape. However, it is very difficult to assemble the brushes so that they can be slidably contacted with the cylindrical commutator with proper pressure. Moreover, since it is a cylindrical commutator type, a considerable space is required in the axial direction, so that the length of the rotor is substantially sacrificed, which is not preferable in terms of characteristics. As a countermeasure against this, as shown in the cross-sectional view of the main part of FIG. 4, it is conceivable to use a flat plate commutator C and slide the brush B in the axial direction. With this structure, the assembly is easy, and the space occupied in the axial direction as a power supply device is reduced, so the rotor length can be effectively used and the problem of characteristics is improved, but this time, the amount of deflection of the brush is The problem will be exacerbated.

An object of the present invention is to increase the amount of deflection of the brush as a power supply device for a thin cylinder type DC motor to reduce variations in the sliding contact pressure of the brush. By making the rotor thinner, the drive element portion of the rotor can be made longer and the characteristics are not sacrificed.

[0005]

In order to solve the above problems, according to the present invention, a flat plate commutator arranged on a rotor is slidably contacted with a brush arranged on a bracket in the axial direction. In a power supply device for a small DC motor, the bracket (2) has a terminal (3) as a diaphysis.
It is made of synthetic resin embedded so that
Brush planting at the bottom of the bracket as part of the
The installation part (3a) is exposed.
The base end (4a) of the brush (4) is planted,
Rises from the base end in the axial direction and bends in the radial direction
Sliding part (4c) and brush tip on the commutator.
This can be achieved by a structure including a sliding contact portion (4b) that is in contact with and flexes in the axial direction . As a result, the amount of flexural displacement of the brush can be made large by utilizing the thickness of the bracket, and the variation in the brush sliding contact pressure can be reduced, and the bracket is embedded in the synthetic resin so that the terminal serves as the diaphysis. By forming by (3), even if the brush installation portion of the terminal is exposed at the bottom portion of the bracket or the bottom portion of the terminal, there is no risk of peeling of the terminal and there is no problem in strength. As a result, the thickness of the bracket can be effectively used. In addition, according to a second aspect of the present invention, the terminal includes a brush planting portion (3
When a) is exposed axially outward from the bracket
Both of them have a mounting terminal (3b), part of which also serves as power supply.
Then, it may be projected in the radial direction. With this configuration, the printed wiring board can be easily placed and fixed by soldering.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional front view of the essential parts of a first embodiment of a power supply device for a small DC motor according to the present invention, and FIG.
FIG. 3 is a sectional side view of an essential part of the second embodiment, and FIG. 3 is a sectional view of an essential part of a modified example of the second embodiment.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the construction of a concrete first embodiment of the present invention will be described with reference to the sectional front view of the essential portions shown in FIG. In the figure, reference numeral 1 denotes a thin tubular case in which a bracket 2 made of a slidable synthetic resin is fitted in the opening, and a terminal 3 is embedded in the bracket 2 so as to serve as a diaphysis, and a bottom portion thereof is A part is exposed as the brush planting portion 3a, and is projected outward from the outer diameter of the case 1 as the power supply terminal 3b. The base end 4a of the thin plate brush 4 clad with a noble metal is spot-welded to the brush planting portion 3a. This thin plate brush 4 has a rising portion 4c that is axially raised from the base end 4a in order to effectively utilize the thickness of the bracket 2, and the upper end of the bracket 2 is bent in the radial direction and the tip end thereof is bent. 4b has a sliding contact portion which has a roundness and contacts the flat plate commutator 5 arranged on the rotor R. That is, in the thin plate brush 4 thus configured, the effective length for determining the amount of deflection can be increased by the thickness of the bracket 2. For this reason, the amount of deflection for obtaining a predetermined sliding contact pressure can be increased, and variations in the sliding contact pressure are reduced. The rotor R includes a core b having teeth a formed by laminating a plurality of silicon steel plates, an armature coil 7 wound around the teeth, and a bearing 9 arranged on the case 1 via a shaft 8 and a bracket 2 itself. It is rotatably supported by the configured bearing 2a,
It receives the magnetic force of the cylindrical magnet M and functions as a motor by the electric power input from the power supply terminal 3b. In the figure, W is an eccentric weight arranged at the output part of the shaft 8 for generating vibration, T is a mounting terminal arranged at the bottom of the case, and together with the power supply terminal 3b,
This is for placing the motor main body on the printed wiring board P indicated by the imaginary line by laying it down by soldering or the like. The posture where the motor is laid down so that the opposite side of the mounting terminal does not go out from the upper surface of the case. Is taken into consideration so that it does not become high.

The cross-sectional side surface of the main part shown in FIG. 2 is applied to a radial sliding contact type as a second embodiment of the present invention.
That is, in the figure, the thin plate brush 44 is spotted on the brush planting portion 3a at the base portion 44a, is raised in the thickness portion of the bracket 2, is extended in the radial direction, and is slidably contacted with the cylindrical commutator 55. It is like this. Therefore, the effective length that determines the amount of flexure of the brush can be made longer than that of the one arranged above the bracket.

As shown in FIG. 3, as a modification, the thin plate brush 444 is folded back in the radial direction within the thickness of the bracket 2 to further increase the effective length.
By doing so, the amount of deflection of the brush can be further increased, so that the variation of the sliding contact type is reduced.

In each of the above embodiments, the rotor structure is exemplified as the cored type, but it is needless to say that the coreless type is applicable, and the brush may be a linear brush instead of a thin plate.

[0011]

As described above, the power feeding device according to the present invention is configured to utilize the thickness of the bracket in order to increase the amount of deflection of the brush. Therefore, although the brush is slender, the brush can be slidably contacted with the commutator. Variations in sliding contact pressure can be reduced, and a long-life motor can be provided.

[Brief description of drawings]

FIG. 1 is a sectional front view of a main part of a first embodiment of a power supply device for a small DC motor according to the present invention.

FIG. 2 is a sectional side view of a main part of the second embodiment.

FIG. 3 is a sectional view of an essential part of a modification of the second embodiment.

FIG. 4 is a sectional view of a main part of a conventional power supply device for a small DC motor.

[Explanation of symbols]

1 case 2 bracket 3 terminals 3a Brush planting section 3b Power supply terminal 4,44,444 Thin plate brush 4c Startup section

Claims (2)

(57) [Claims] 1. A power supply device for a small DC motor, comprising a flat plate commutator arranged on a rotor and a brush arranged on the bracket slidably contacting the bracket in the axial direction.
(2) is buried so that the terminal (3) becomes the diaphysis
It is made of synthetic resin and is used as a part of the terminal.
At least the inside of the racket at the bottom of the racket (3
a) is exposed, and the brush is installed in the brush planting part.
The base end (4a) of (4) is planted, and the brush is the base end.
A rising part that rises axially from the axis and bends in the radial direction
(4c) and the tip of the brush comes into sliding contact with the commutator.
A power supply device for a small DC motor, which comprises a sliding contact portion (4b) that flexes in the axial direction . 2. The terminal is a brush planting portion (3a).
Is also exposed axially outward from the bracket.
In addition, a part of it is used as a mounting terminal (3b) that also serves as power supply.
The power supply device for a small DC motor according to claim 1, wherein the power supply device is radially projected .