JPH023382B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brush structure for a small motor, and more particularly to a brush holding structure used in a small DC motor equipped with a commutator.

Conventionally, in this type of small motor brush, a leaf spring was used as a holding spring 7 for holding the brush 6, and a terminal plate 33 was welded to one end of this holding spring 7, as shown in FIG. . Therefore, the spring constant of the holding spring 7 becomes large, and in order to make the spring constant suitable for a small DC motor with a small rotational torque, it is necessary to divide the holding spring 7 into a plurality of pieces in the width direction. Such machining becomes more difficult as the size becomes smaller, and the machining accuracy tends to be lower, which has the disadvantage that the brush 6 cannot be brought into stable contact with the commutator 8. On the other hand, if the thickness of the retaining spring 7 is reduced in order to reduce the spring constant, welding to the terminal plate 33 becomes difficult. In addition, in order to fix the retaining spring 7 in a fixed position, a claw 34 provided on the terminal plate 33 is inserted into the terminal hole 10 of the bracket 3.
However, the contact position of the brush 6 to the commutator 8 and the contact position of the brush 6 may vary depending on the welding strength between the holding spring 7 and the terminal plate 33, the accuracy of the welding position, the positional accuracy of the press-fit, and the holding force of the press-fit. The drawbacks were that pressure was easily affected, the yield was poor, and the lifespan was short.

The present invention has been made to solve the above-mentioned conventional drawbacks, and its main purpose is to integrate the retaining spring and the terminal to eliminate welding points, thereby reducing the difficulty of processing by welding. Another purpose is to hold the brush in a position separated from the commutator when the brush is assembled, and to make the brush contact the commutator with a predetermined contact force after assembly, so that the assembly work can be carried out. It's about making it easier.

Embodiments of the present invention will be described below based on the drawings. The brush structure of a small motor according to the present invention has a bracket 3 attached to one end of a casing 2 in the axial direction of a rotor 1, a support column 4 protruding from the inner surface of the bracket 3, and a torsion coil on the outer periphery of the support column 4. A spring 5 is inserted, and a holding spring 7 having a brush 6 at its tip extends from one end of the torsion coil spring 5, and the spring force of the torsion coil spring 5 urges the brush 6 in the direction of contacting the commutator 8. The terminal wire 9 extending from the other end of the torsion coil spring 5 projects outside the casing 2 through the terminal hole 10 formed in the bracket 3, and the holding spring 7 is held at a position where the brush 6 is separated from the commutator 8. A temporary fixing pin 31 that locks against the spring force of the torsion coil spring 5 is protruded from the inner surface of the bracket 3, and a holding spring 7 is provided at a position corresponding to the holding spring 7 that is locked to the temporary fixing pin 31. It is characterized in that a through hole 32 is formed into which a jig for releasing the lock with the temporary fixing pin 31 is inserted.
In this embodiment, a cup-type coreless motor is exemplified. As shown in FIG. 2, the casing 2 is formed of a cylindrical frame 12 with a bottom and a bracket 3 that closes the open end of the frame 12.
and a stator 15 having magnet pieces 14 disposed inside the rotor 1. The magnet piece 14 is held by a yoke 16 fixed to the frame 12, and a shaft hole 18 is formed in the center of the yoke 16, into which a rotating shaft 17 is inserted. Bearings 19 are mounted on both ends of the yoke 16 on the circumferential surface of the shaft hole 18 . One end of the rotor coil 13 on the side of the bracket 3 is fixed to the outer periphery of a disc-shaped base 20, and a rotating shaft 17 is inserted and fixed in the center of the base 20. A ring-shaped surge absorbing varistor 21 is fixed to one surface of the base 20, and electrodes provided on the surface of the varistor 21, terminals of the rotor coil 13, and the commutator 8 are fixed by soldering. Commutator 8 is rotor coil 13
The brush 6 is formed into a substantially L-shape in which a segment 23 that slides into contact with the brush 6 rises from a riser 22 that is soldered to the riser 22 , and the segment 23 is fixed to a commutator base 24 that is inserted into the rotating shaft 17 . A torsion coil spring 5 is attached to the bracket 3 for applying contact pressure to the brush 6 in contact with the commutator 8. That is, as shown in FIG. 3, a cylindrical support column 4 is provided protruding from the inner surface of the bracket 3, and a torsion coil spring 5 is inserted into the outer periphery of the support column 4. A linear retaining spring 7 extends from one end on the tip side, and a terminal wire 9 extends from one end on the base side of the support column 4 of the torsion coil spring 5. A brush 6 made of carbon is fixed to the tip of a retaining spring 7 extending along the circumferential direction from one end of the torsion coil spring 5. Further, a terminal wire 9 extending from the other end of the torsion coil spring 5 projects to the outside of the casing 2 through a terminal hole 10 formed in the bracket 3 and penetrating inside and outside. By the way, terminal hole 1
0 is formed as a long hole extending in the radial direction of the bracket 3, as shown in FIG. However, the torsion coil spring 5
The terminal wire 9 extending from one end is bent into an L shape, passed through the terminal hole 10, and the bent portion of the terminal wire 9 is inserted into the locking piece 3.
0, the torsion coil spring 5
This prevents the terminal wire 9 from coming off in the axial direction of the support column 4, and also prevents the terminal wire 9 from wobbling. The torsion coil spring 5 has a spring force that urges the brush 6 toward the commutator 8, and when this spring force acts, the terminal wire 9 comes into pressure contact with the locking piece 30. As shown in FIGS. 3 and 4, on the inner surface of the bracket 3, there is a temporary fixing pin 3 that locks the retaining spring 7 against the spring force of the torsion coil spring 5 at a position where the brush 6 is separated from the commutator 8.
1 is provided protrudingly. A through hole 32 is formed in the bracket 3 to correspond to the retaining spring 7 which is engaged with the temporary fixing pin 31 and penetrates from the inside to the outside. Therefore, by locking the tip of the retaining spring 7 to the temporary fixing pin 31, it becomes easy to prevent the brush 6 from hitting the commutator 8 when the bracket 3 is attached to the frame 12.
After assembling the casing 2, in order to bring the brush 6 into contact with the commutator 8, a jig such as a pin is inserted through the through hole 32 and the holding spring 7 is pushed, thereby locking the temporary fixing pin 31 and the holding spring 7. It will be lifted. Here, since the contact pressure of the brush 6 against the commutator is obtained by the torsion coil spring 5, the spring force will not weaken even if the retaining spring 7 is retained on the temporary fixing pin 31 for a long time. be.

As described above, the present invention includes a support column protruding from the inner surface of the bracket, a torsion coil spring inserted into the outer periphery of the support column, and a retaining spring having a brush at the tip extending from one end of the torsion coil spring. Since the terminal wire extends from the other end of the torsion coil spring, the retaining spring and the terminal wire are integrated to bring the brush into contact with the commutator, and there is no need to weld the retaining spring and the terminal wire as in the conventional method. This has the advantage of reducing the number of parts and improving the precision of the parts, and since the brush is pressed against the commutator by the spring force of the torsion coil spring, the contact between the brush and the commutator is stable. It has the advantage of Further, in the present invention, a temporary fixing pin that locks the holding spring against the spring force of the torsion coil spring at a position where the brush is separated from the commutator is provided protruding from the inner surface of the bracket, and the holding spring and the temporary fixing pin are locked. A through hole is formed into which a jig to release the brush is inserted, so if you lock the retaining spring to the temporary fixing pin during assembly, there is no need to spread the retaining spring by hand to separate the brush from the commutator. , it is sufficient to simply fit the frame of the casing and the bracket, and then use a jig such as a pin through the through hole to release the temporary fixing pin from the retaining spring.
As a result, assembly work becomes easier.
In addition, since the brush is urged toward the commutator by a torsion coil spring, the spring force does not weaken even if the retaining spring is locked to the temporary fixing pin for a long time, and the brush can be brought into contact with the commutator with stable pressure. It is something that can be done. Furthermore, in the present invention, since the brush attached to one end of the torsion coil spring is brought into contact with the commutator, the contact area between the brush and the commutator is not limited by the diameter of the torsion coil spring, and the commutator is This has the advantage that the contact resistance between the child and the brush can be reduced, and the contact between the two is also stable. Furthermore, in the present invention, since the terminal wire extending from the other end of the torsion coil spring projects outside the casing through the terminal hole formed in the bracket, the brush can be attached to the bracket by passing the terminal wire through the terminal hole. In addition, since the other end of the torsion coil spring protrudes outside the casing and becomes the terminal wire, there is little contact resistance on the terminal side, and because the contact resistance is low, there is no heat generation. It has the effect of being small.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a conventional example, FIG. 2 is a sectional view showing an example of a small motor using the present invention, and FIG.
The figure is a perspective view of the main part of the present invention, and FIG.
is a bracket, 4 is a support column, 5 is a torsion coil spring, 6 is a brush, 7 is a holding spring, 8 is a commutator, 9 is a terminal wire, 10 is a terminal hole, 31 is a temporary fixing pin, 32
is a through hole.

Claims (1)

[Claims] 1 A bracket is attached to one end of the casing in the axial direction of the rotor, a support column is provided protruding from the inner surface of the bracket, a torsion coil spring is inserted into the outer periphery of the support column, and a torsion coil spring is inserted from one end of the torsion coil spring to the tip. A retaining spring having a brush extends, and the spring force of the torsion coil spring urges the brush in a direction to abut the commutator, and the terminal wire extending from the other end of the torsion coil spring connects to the terminal hole in which the bracket is formed. A temporary fixing pin that protrudes outside the casing through the bracket and locks the retaining spring against the spring force of the torsion coil spring at a position where the brush is separated from the commutator is provided on the inner surface of the bracket and is locked to the temporary fixing pin. A brush structure for a small motor, characterized in that a through hole into which a jig for releasing the lock between the holding spring and the temporary fixing pin is inserted is formed at a position corresponding to the held holding spring.