JPH0287952A - Small-sized motor - Google Patents

Abstract

PURPOSE:To control generation of vibration and noise by pressure welding and fixing one end of a plastic brush holder via an elastic body to the end face of a cylindrical yoke arranged at the inner periphery of a plastic motor housing. CONSTITUTION:A motor housing 2 and an end cover 3 constitute the outer shape of a motor and both are molded out of plastics. Then, a high rigidity cylindrical yoke 14 for forming the magnetic path of a motor is fitted to the inner periphery of said motor housing 2. In this case, one end 11 of a brush holder 7 is pressure welded and fixed via an elastic body 12 to the end face of said high rigidity iron cylindrical yoke 14. Further, a base 9 surface near the brush holder 7 is pressure welded and fixed to the inside of the end cover 3 via a second elastic body 17. In this manner, vibration generated between a brush 6 and a commutator 4 is absorbed in a position near the source of its vibration in the form of holding said brush 6 in between. Therefore, it is possible to perform vibration damping and to improve the depression effect of vibration and noise of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small electric motor, and more particularly to the structure of mounting an elastic body for suppressing vibration (noise) of the electric motor.

[Conventional technology]

In electric motors with brushes, the sliding friction between the brushes and commutator is a source of vibration and noise. Therefore, for example, in the field of small electric motors such as automobile blowers, various countermeasures have been conventionally taken. for example.

As disclosed in Japanese Utility Model Publication No. 52-24725, a protrusion is provided inside the housing of the motor, an elastic body is attached to the outer edge of a brush holding insulating plate housed in the housing, and the elastic body is attached to the protrusion. The tightening is fixed between the part and the end frame (end cover), or
No. 4, Japanese Unexamined Patent Publication No. 58-175947, etc., an elastic coating was formed on the inner wall surface of the brush, and an elastic coating was formed on the surface of the base body to absorb vibrations. .

[Problem to be solved by the invention]

Incidentally, in recent years, in the field of small electric motors, there has been a trend to make parts such as housings made of plastic due to the need for weight reduction. When a plastic molded product is used for the electric motor housing, the rigidity of the housing is significantly lower than that of a metal housing. Low rigidity of the housing leads to a decrease in vibration absorption efficiency.

Therefore, in the above-mentioned elastic body mounting method (method in which an elastic body is interposed between the end frame and the housing) of Utility Model Publication No. 52-24725, when the housing is made of plastic, the vibrations from the brush side are sufficiently absorbed by the elastic body. A new problem has arisen that cannot be solved. In addition, in this method, the elastic body of the brush insulating plate is mounted relatively far away from the brush holder, so indirect vibration damping is achieved at a location far from the brush vibration source, and the damping ratio increases accordingly. tended to decrease.

On the other hand, when an elastic body is provided in the brush holder as in JP-A No. 55-23774, it is a vibration suppression means with the highest damping ratio, and the above-mentioned problem can be avoided, but the elastic body coating is costly. In addition, there was a problem in that it was technically difficult to control the dimensional accuracy of the elastic coating to ensure brush sliding properties.

JP-A-58-175947 has a structure intermediate between these, but like the former, there are points that should be improved in terms of cost and dimensional accuracy control associated with the molding of elastic coatings.

The present invention has been made in view of the above points, and its purpose is to fully meet the demands for both plasticization (light weight) of parts such as motor housings and suppression of vibration and noise. It is an object of the present invention to provide a small electric motor that does not require strict dimensional control accuracy of a noise suppression mechanism, is cost-effective, and is easy to assemble.

[Means to solve the problem]

The present invention takes the following measures to achieve the above object.

Hereinafter, the present invention will be explained in the first part to facilitate understanding of its contents.
The embodiments shown in the figures will be described with reference to the reference numerals.

That is, the present invention provides a small electric motor comprising a brush holder 7 that accommodates and holds a brush 6, a rotor 5 having a commutator 4 that makes sliding contact with the brush 6, etc., in which the brush holder 7 is attached to a base for supporting the holder. 9, a highly rigid cylindrical yoke 14 is integrally molded with the base from plastic, the motor housing 2 is also molded from plastic, and the magnetic path of the motor is formed on the inner periphery of the motor housing 2.
is fixedly arranged, and one end 11 of the brush holder 7 is press-fitted to the cylindrical yoke 14 via an elastic body 12.

[Effect]

According to the present invention having such a configuration, the electric motor housing 2 is made of plastic to reduce its weight, and one end 11 of the brush holder 7 is formed on the inner periphery of the housing 2 instead of the low-rigidity plastic housing 2. It is press-fixed to one end of the arranged cylindrical yoke 14 for forming a magnetic circuit.

This cylindrical yoke 14 is usually made of iron and has the highest rigidity among the components of the electric motor.
The vibration absorption rate of the elastic body 12 in contact with increases. Furthermore, in the present invention, one end 11 of the holder 7 is fixed to the yoke 14 via the elastic body 12, so vibrations are absorbed at a position extremely close to the brush 6 (vibration source), so the vibration damping ratio can be significantly increased. Can be done. That is, due to one or more synergistic effects, the sliding frictional vibrations generated between the commutator and the brushes receive the most effective vibration damping force. Therefore, the sliding frictional vibrations generated between the brush 6 and the commutator 4 are sufficiently absorbed by the elastic body 12 and effectively suppressed from being transmitted to the housing 2 side. It is possible to achieve low vibration and low noise. Moreover,
Even if the elastic body 12 is located near the vibration source, there is no need to apply an elastic coating inside the brush holder, which is difficult to mold, as in the conventional case, and the elastic body at one end of the brush can simply be made into a part of the cylindrical yoke. Since the elastic body is simply fixed by pressure contact, the elastic body can be easily assembled.

〔Example〕

An embodiment of the present invention will be described based on the drawings.

FIG. 1 is a partially cutaway sectional view of a small electric motor according to an embodiment of the present invention applied to an automobile blower.

In FIG. 1, 1 is a centrifugal fan used for blowing air, 2 is a housing of an electric motor, and 3 is an end cover. The housing 2 and end cover 3 constitute the outer shape of the electric motor. The housing 2 and end cover 3 are molded from plastic, and a highly rigid cylindrical yoke 14 is fitted on the inner periphery of the housing 1 to form a magnetic path for the electric motor. A permanent magnet 13 serves as a field pole (stator), and is fixedly arranged on the inner circumference of the cylindrical yoke 14.

Inside the electric motor, there is a rotor 5° with a commutator 4 and brushes 6.
, a brush holder 7, a holder base 9, etc. are incorporated.

Here, the structure of the brush 6, brush holder 7, base 9, etc. will be explained with reference to FIG.

FIG. 2 is an exploded perspective view showing the brush holding assembly 10 and the end cover 3 in this embodiment. In the figure, (A) shows the state when the brush holding assembly 10 is assembled inside the end cover 3. (b) represents the brush holding assembly 10
Represents the state upside down.

As is clear from FIG. 2(a), the base 9 has a rectangular plate shape, and has a hole 9a formed in the center thereof through which the rotor shaft is inserted. On one side of the base 9, there is a
As shown in the figure, a pair of rectangular brush holders 7 have 18
They are arranged facing each other with an interval of 0°. The brush holder 7 and base 9 are integrally molded from plastic. Each brush holder 7 is open at both ends as shown in FIG.
is accommodated, and the brush 6 is attached to the rear end side or by a spring (described later).
It is applied to the end 8a of the helical spring 8 and is elastically supported.

At the position adjacent to each brush holder 7 on the base 9 surface,
A support post 18 is formed, a spring 8 is fitted into the support post 18, and one end 8a of the spring 8 extends to one end (rear end) of the opening of the brush holder 7, and this spring end 8a connects the brush 6 to the commutator 4.
Support while biasing to the side. The strut 18 and the base 9 are integrally molded of plastic.

A part of the brush 6 protrudes from the tip of the brush holder 7,
A tongue-like projection 11 is integrally provided with the brush holder 7 and protrudes outward at the rear end. A rectangular parallelepiped elastic body (insulating elastic member) 12 is inserted into the tongue-like protrusion 11 .

On the surface of the base 9 on the side opposite to the brush holder, a second cylindrical elastic body 17 is fixedly arranged at each corner.

This cylindrical elastic body 17 is press-fitted into a protrusion 16 provided on the base 9, as shown in FIG.

When such a brush holding assembly 10 is assembled inside the end cover 3, the rotor shaft is inserted into the insertion hole 9a of the base 9 with the tips of the brushes 6 in opposing contact with the outer peripheral surface of the commutator 4. An elastic body 12 inserted through the tongue and attached to the tongue-shaped projection 11
is fitted into the notched recess 15 provided at one end of the cylindrical yoke 14, and the second elastic body 17 is interposed between the base 9 and the inside of the end cover 3, and the small flange of the end cover 3 3a into the motor installation flange (large flange 24) on the housing 2 side, and
This is done by tightening the screws together. According to such attachment, a narrowing force acts between the end cover 3 and the cylindrical yoke 14, and the elastic compression body 12.17 is appropriately compressed by this narrowing force.

Specifically, the force from the cylindrical yoke 15 acts on the elastic body 12, and the force from the end cover 3 acts on the elastic body 12 at f52.
Elastic body 17. Base 9. By acting through the brush holder 7 and the tongue-like protrusions], ], the elastic body 12 is pressed and fixed to the end surface of the cylindrical yoke 15. Second elastic body 17
is sandwiched between the base 9 and the inside of the end cover 3.

Next, connection of the brush 6 to an external power source will be explained.

As shown in FIG. 2(A), one surface of the brush holder 7 has a notch 7a, one surface of the base 9 has a pair of notched grooved protrusions (guide grooves) 21a, 21b, and a small portion of the end cover 3. The flange 3a has a small hole 23a.

23b and the protrusion guide 22 are formed.

Further, as shown in FIG. 1, the flange 2 of the housing 2
4 is formed with a connector 25 for external connection. Conductive wire (pigtail) 19a of each brush.

Standard terminals 20a and 20b of an external connection connector are attached to the tip of 1-9b.

Standard terminals 20a, 20b and conductive wire 19a.

1 and 9 b are notches 7 provided in each brush holder 7.
a, guide grooves 21a, 21b of base 9, end cover 3
A numbered ventilation window 3b, a protrusion guide 22 and a small hole 2.
3a and 23b (7, inserted and fixed into the external connection connector part 25), connection to an external power source is possible via this external connection connector 25. In addition, base 9
To prevent a short circuit between the conductive wires 19a, 19b and the commutator 4 after assembling the brush holding assembly O, a protective guide 26 is installed on the commutator side as shown in FIG. will be distributed.

According to this embodiment, the following effects are achieved.

First, in order to reduce the weight by using plastic molded parts for the electric motor housing 2, end cover 3, brush holder 7, base 9, etc., one end of the brush holder in this example is used. 1], instead of the low-rigidity plastic housing 2, a structure is adopted in which the end face of a high-rigidity iron cylindrical yoke 14 is pressed and fixed via an elastic body 12.
The surface of the base 9 closest to the holder 7 is connected to the second elastic body 1.7.
Since the brushes 6 and commutator 4 are press-fitted to the inside of the end cover 3, the sliding friction vibrations generated between the brushes 6 and the commutator 4 are absorbed by sandwiching the brushes (3) at a position close to the vibration source. It can provide effective vibration damping and improve the effect of suppressing the vibration and noise of the motor.6Moreover, the installation of the elastic body 12.17 is extremely quick and easy, and the dimensional accuracy is better than the conventional elastic body coating. It is advantageous compared to varnishes because it does not require the strictness of a method.

Secondly, the connection of the brush 6 to the external connection connector 25 is made through the guide hole 2 provided in the base 9.

21b, ventilation window 3b of end cover 3, protrusion guide 22
．． Conductive wires J, 9a, ] using small holes 23a, 23b, etc.
, a standard terminal 20a provided at the tip of 9b.

20b can be directly inserted into each connector 25, so one assembly is easy. Furthermore, standard terminals 20a on the + side and - side
, 20b and the conductive wires L9a, 19b are connected to the guide hole 2], a, 21b provided in the base 9, and the protrusion guide 22 and small hole 23a of the end cover.

Since they are separated at 23b, the conductive wires are prevented from becoming twisted and are insulated, thereby improving the reliability of the motor.

Thirdly, since the holder 7 and the base 9 are integrally molded from plastic, assembly work can be simplified. Conventionally, the holder, base, etc. were separated and reassembled, which took time and effort, and the assembly was difficult because connectors, harnesses, etc. were used to connect conductive wires from the brush to the external connector. Simplification of attachment was desired.

〔Effect of the invention〕

As described above, the present invention satisfies both the demands for plasticization (light weight) of electric motor housings, etc. and suppression of vibration and noise, and also improves the accuracy and strictness of dimensional control of the vibration and noise suppression mechanism. It is possible to provide a small electric motor that is not required, is easy to assemble, and is advantageous in terms of cost.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view showing one embodiment of the present invention, and FIG. 2 is an exploded perspective view of an end cover and brush holding assembly used in the above embodiment. 2...ttt1 machine housing, 3...end cover, 3b...ventilation window, 4...commutator, 5...rotor, 6...brush, 7...brush holder, 9 ...Base, 11...Brush holder end, 12...Elastic body,
14... Cylindrical yoke 517... Second elastic body, 1
9a, 19b... Conductive wire, 20a, 20b-=terminal for external connection, 21a, 21b... Guide hole, 22... Projection guide, 23a, 23b... Small hole, 24... Flange, 25 ...Connector for external connection.

Claims (4)

[Claims] 1. In a small electric motor consisting of a brush holder that accommodates and holds brushes, and a rotor having a commutator that makes sliding contact with the brushes, the brush holder is integrally molded of plastic together with the base on a base for supporting the holder. , and the motor housing is also made of plastic, a highly rigid cylindrical yoke that forms a magnetic path for the motor is fixedly arranged on the inner periphery of the motor housing, and an elastic body is attached to one end of the brush holder on the end face of the cylindrical yoke. A small electric motor characterized by being press-fitted and fixed through a wire. 2. In the first claim, the base for supporting the holder is disposed facing inside an end cover provided at one end of the motor housing, and a second elastic body is interposed between the end cover and the base. Small electric motor. 3. In the first or second claim, a flange for installing the motor is formed on the outer periphery of the motor housing, a connector for external connection is provided on the flange, and one end of a conductive wire extending from the brush of the brush holder is provided with a flange for installing the motor. Attach an external connection terminal, and insert and fix this external connection terminal into the inside of the external connection connector through a guide hole provided in the base, a ventilation window, a protrusion guide, and a small hole provided in the end cover. A small electric motor. 4. In the third claim, a guide hole provided in the base;
The protrusion guide and the small hole provided in the end cover allow the positive conductive wire and the negative conductive wire of the conductive wire to be inserted while being separated from each other to prevent the conductive wires from becoming twisted and to insulate them. A small electric motor.