JPH0621367U - Electric motor - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an electric motor, and an object of the present invention is to provide an electric motor that prevents rotation failure of the motor due to clogging between commutator pieces due to abrasion of the brush. [Structure] The brush holder 3 is provided on the outer periphery of a drum-shaped commutator 27 in which a plurality of commutator pieces 29 are annularly arranged.
The tip 15a of the brush 15 slidably held in
In an electric motor that is abutted by a spring 19 interposed in the brush holder 31, the brush holder 31 is rotatably attached to the motor casing 1 so as to be rotatable in the axial direction of the center line of the commutator 27. A spring for moving the brush holder 31 in the rotational direction between the brush holder 31 and the motor casing 1 according to wear of the brush 15 while forming a flare shape in which the outer periphery is formed in an arc shape along the locus of 31. 33
Attached.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to improvements in electric motors.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, an electric motor for driving a cooling fan of a vehicle radiator has a bearing 3 made of a sintered metal in which upper and lower ends of a motor casing 1 are impregnated with oil, as shown in Japanese Utility Model Laid-Open No. 61-114968 or FIG. Is mounted, and the rotating shaft 5 is supported by the bearing 3. A magnet 9 is arranged on the inner peripheral surface of the motor casing 1 so as to face the rotor 7 attached to the rotary shaft 5.

A drum-type commutator 13 in which a plurality of commutator pieces 11 are arranged around the central axis L of the rotary shaft 5 is attached near the rotor 7, and the outer peripheral surface of the commutator 13 is attached. A pair of brushes 15 is in contact with the.

The brush 15 is slidably held in a brush holder 17 having a rectangular cross section fixed to the inner peripheral surface of the motor casing 1, and a spring 19 is interposed in the brush holder 17. . The tip end 15a of the brush 15 is brought into contact with the commutator 13 by the spring force of the spring 19 to supply power to the commutator 13.

In addition, in the figure, 21 is an oil-impregnated felt, 23 is a material for supporting the bearing 3, and 25 is a thrust washer.

[0006]

[Problems to be solved by the device]

 Thus, conventionally, the brush 15 mainly contains carbon or graphite, and the tip 15a of the brush 15 gradually wears as the commutator 13 rotates.

However, since the brush 15 is always in contact with the same portion of the outer circumference of the commutator 13, the abrasion powder of the brush 15 causes this contact surface, that is, the commutator piece 11 in the range shown by the diagonal line A in the figure. There is a risk of clogging between them and, as a result, the motor may malfunction due to long-term use.

The present invention has been devised in view of the above circumstances, and an object thereof is to provide an electric motor in which clogging between commutator pieces due to abrasion of a brush is eliminated and rotation failure of the motor is prevented. To do.

[0009]

[Means for Solving the Problems]

 In order to achieve such an object, the present invention provides a brush holder, which is slidably held in a brush holder, on the outer periphery of a drum-shaped commutator in which a plurality of commutator pieces are annularly arranged. In an electric motor that is abutted by a spring interposed inside, the brush holder is attached to the motor casing so as to be rotatable in the axial direction of the center line of the commutator, and the commutator is moved along the path of the brush holder. The outer periphery of the brush holder is flared in a circular arc shape, and a spring is attached between the brush holder and the motor casing to move the brush holder in its rotation direction as the brush wears.

[0010]

[Action]

 According to the present invention, when the tip of the brush contacting the commutator is gradually worn, the brush is pushed out of the brush holder by the spring in the brush holder, but the brush is worn between the brush holder and the motor casing as the brush wears. The spring force of the spring causes the brush holder to move sequentially in the rotation direction, and the contact surface of the brush tip with respect to the commutator changes.

[0011]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same parts as those in the conventional example shown in FIG. 2 are designated by the same reference numerals, and their description will be omitted.

In FIG. 1, 27 is a drum-type commutator in which a plurality of commutator pieces 29 are arranged, and the commutator 27 is sequentially expanded to the rotor 7 side along a locus of a brush holder 31 described later. It has a flared cross-section with its outer periphery shaped like an arc so that it opens. The commutator pieces 29 are annularly arranged so that the commutator pieces 29 (conductive portions) in the central axis L direction of the commutator 27 and the gaps (insulating portions) therebetween are the same. .

Reference numeral 31 denotes a brush holder having a rectangular cross section which is rotatably mounted on the inner circumference of the motor casing 1 in the direction of the center line axis L of the commutator 27. The brush 15 is slidable in the brush holder 31. Is held. As in the conventional case, the tip 15a of the brush 15 is always in contact with the outer periphery of the commutator 27 by the spring force of the spring 19 interposed in the brush holder 31.

A spring 33 is attached between the brush holder 31 and the motor casing 1 to move the brush holder 31 in one direction (the direction of arrow B in the figure).

When the brush 15 is not worn, as shown in the figure, the spring 19 resists the spring force of the spring 33 to bring the brush 15 into contact with the outer circumference of the commutator 27 on the rotor 7 side. The spring force of the springs 19 and 33 is set. Then, as the tip 15a of the brush 15 wears, the spring 19 slightly expands to bring the brush 15 into contact with the commutator 27 and the spring force is weakened. The holder 31 is sequentially moved in the direction of arrow B, and the contact surface of the brush 15 with respect to the commutator 27 is gradually changed in the moving direction of the brush holder 31 (the direction of arrow B in the figure).

Since the present embodiment is configured in this way, as shown by the solid line in FIG. 1, the brush 15 at the beginning of use has a spring force of the spring 19 that opposes the spring force of the spring 33. The tip 15a comes into contact with the outer circumference of the commutator 27 on the rotor 7 side to supply power to the commutator 13.

When the tip 15a of the brush 15 gradually wears with use, the brush 15 is sequentially pushed out of the brush holder 31 by the spring force of the spring 19, and thus the brush 15 is worn by the spring 19 so that the brush 15 springs. As the spring 19 pushes the brush 15 against the commutator 27, the spring 19 expands to weaken the spring force, and the spring 33 moves the brush holder 31 in the direction of arrow B by the spring force of the weakened spring 19. Therefore, as the tip 15a of the brush 15 wears, the brush holder 31 gradually moves in the direction of arrow B as shown by the chain double-dashed line, and the contact surface of the tip 15a with respect to the commutator 27 changes in the same direction. It will be.

As described above, unlike the conventional example shown in FIG. 2, the electric motor according to the present embodiment does not have a structure in which the tip 15a of the brush 15 is always in contact with the same outer peripheral portion of the commutator 27. Since the contact surface with the commutator 27 changes with the wear of the tip 15a, according to the present embodiment, the abrasion powder of the brush 15 causes a partial gap between the commutator pieces 29 of the commutator 27. Clogs no longer occur, and as a result, there is no longer a risk that the motor will malfunction due to long-term use.

[0019]

[Effect of device]

 As described above, according to the present invention, the contact surface of the brush with the commutator changes as the tip of the brush wears.Therefore, according to the present invention, the commutator commutator of the commutator is changed by the abrasion powder of the brush. There is no partial clogging between the two parts, and as a result, there is no risk that the motor will fail to rotate during long-term use, and durability can be improved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part of an electric motor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a conventional electric motor.

[Explanation of symbols]

 1 Motor Casing 7 Rotor 15 Brush 15a Tip 19,33 Spring 27 Commutator 29 Commutator Piece 31 Brush Holder

Claims (1)

[Scope of utility model registration request] 1. A brush (1) slidably held in a brush holder (31) on the outer periphery of a drum type commutator (27) having a plurality of commutator pieces (29) arranged in an annular shape.
In an electric motor in which the tip (15a) of 5) is brought into contact with a spring (19) interposed in the brush holder (31), the brush holder (31) is moved in the axial direction of the center line of the commutator (27). Is rotatably attached to the motor casing (1), and the commutator (27) has a flare shape in cross section whose outer circumference is formed in an arc shape along the trajectory of the brush holder (31). An electric motor, characterized in that a spring (33) for moving the brush holder (31) in the rotation direction thereof is attached between the motor casing (1) and the motor casing (1) when the brush (15) is worn.