JPH0667145B2 - Small electric motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small electric motor, and more particularly to an elastic body mounting structure for suppressing vibration (noise) of the electric motor.

[Conventional technology]

In a motor with a brush, sliding friction between the brush and the commutator is a source of vibration and noise. Therefore, for example, in the field of small electric motors such as blowers for automobiles, various measures have been conventionally taken. For example, as disclosed in Japanese Utility Model Publication No. 52-24725, a protrusion is provided inside a housing of an electric motor, and an elastic body is attached to an outer edge portion of a brush holding insulating plate housed in the housing. Tighten and fix between the protrusion and the end frame (end cover),
As disclosed in JP-A-55-23774 and JP-A-58-175947, an elastic film is formed on the inner wall surface of the brush or an elastic film is formed on the surface of the base body to absorb vibration. I was trying.

[Problems to be Solved by the Invention]

By the way, in recent years, in the field of small electric motors, there is a tendency to make components such as a housing plastic because of the need for weight reduction. When a plastic molded product is used for the motor housing, the rigidity of the housing is significantly reduced as compared with the metal housing. The low rigidity of the housing reduces the vibration absorption efficiency. Therefore, in the elastic body mounting method (method in which an elastic body is interposed between the end frame and the housing) of the above-mentioned JP-B-52-24725, when the housing is made of plastic, vibration from the brush side is sufficient with the elastic body. A new problem that cannot be absorbed arises. Further, in this method, since the elastic body mounting position of the brush insulating plate is located relatively far from the brush holder, it indirectly suppresses vibration by damping vibration at a position away from the brush vibration source, and the damping ratio Tended to decrease.

On the other hand, when an elastic body is provided in the brush holder as in JP-A-55-23774, it is a vibration suppressing means having the highest damping ratio, and the above-mentioned problem can be avoided, but the elastic film forming is costly. There is a problem in that it causes a rise in height and it is technically difficult to control the dimensional accuracy of the elastic film to secure the slidability of the brush. Japanese Unexamined Patent Publication No. 58-175947 eliminates these intermediate structures, but like the former, there are points to be improved in terms of cost and dimensional accuracy control, which are associated with the elastic film forming.

The present invention has been made in view of the above points, and an object of the present invention is to sufficiently meet the requirements of both plasticization (weight reduction) of components such as an electric motor housing and suppression of vibration and noise, and It is an object of the present invention to provide a small electric motor, which does not require strict dimensional control accuracy of the vibration / noise suppression mechanism, is advantageous in terms of cost, and is excellent in assembling.

[Means for Solving the Problems]

The present invention takes the following means in order to achieve the above object.

The present invention will be described below in order to facilitate understanding of its contents.
An embodiment of the drawing will be described with reference to reference numerals.

That is, the present invention relates to a small electric motor including a brush holder 7 for holding and holding a brush 6, a rotor 5 having a commutator 4 in sliding contact with the brush 6, and the like. The brush holder 7 is a base for supporting the holder. 9 is integrally molded together with the base by plastic, and the electric motor housing 2 is also plastic molded, and a high-rigidity cylindrical yoke 14 forming a magnetic path of the electric motor is fixedly arranged on the inner periphery of the electric motor housing 2. One end 11 of the brush holder 7 is press-contacted and fixed to an end surface of the yoke 14 via an elastic body 12.

[Action]

According to the present invention having such a configuration, the electric motor housing 2 can be plastically molded to reduce the weight thereof, while the one end 11 of the brush holder 7 is replaced with the plastic housing 2 having a low rigidity and is provided on the inner circumference of the housing 2. It is fixed to one end of the arranged cylindrical yoke 14 for forming a magnetic circuit by press contact. The cylindrical yoke 14 is usually made of iron and has the highest rigidity among the components of the electric motor, so that the vibration absorption rate of the elastic body 12 in contact with the yoke 14 increases. Further, in the present invention,
Since the one end 11 of the holder 7 is pressed and fixed to the yoke 14 via the elastic body 12, the vibration is absorbed at a position extremely close to the brush 6 (vibration source), so that the vibration damping ratio can be remarkably increased. That is, due to the above synergistic action, the sliding frictional vibration generated between the commutator and the brush receives the most effective vibration damping force. Therefore, the brush 6 and the commutator 4
The sliding frictional vibration generated between the two is sufficiently absorbed by the elastic body 12 and effectively suppressed from being transmitted to the housing 2 side.
It is possible to reduce the vibration and noise of the electric motor while making the housing plastic. Moreover, even if the elastic body 12 is located near the vibration source, it is not necessary to apply an elastic body coating that is difficult to form in the brush holder or the like as in the conventional case. The elastic body can be easily assembled because it is only fixed by pressure.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway sectional view of a small electric motor, which is 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 the end cover 3 form the outer shape of the electric motor. The housing 2 and the end cover 3 are made of plastic, and a high-rigidity cylindrical yoke 14 for forming a magnetic path of the electric motor is fitted on the inner circumference of the housing 1. 13 is a permanent magnet that serves as a field pole (stator),
It is fixedly arranged on the inner circumference of the cylindrical yoke 14.

A rotor 5 with a commutator 4, a brush 6, a brush holder 7, a holder base 9 and the like are incorporated in the electric motor.

Here, the structure of the brush 6, the brush holder 7, the base 9 and the like will be described 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 FIG. 2, (a) shows a state when the brush holding assembly 10 is assembled inside the end cover 3. (B) shows a state in which the brush holding assembly 10 is turned upside down.

The base 9 has a quadrangular plate shape as is apparent from FIG. 2 (a), and a hole for inserting the rotor shaft in the center thereof.
9a is formed. As shown in FIG. 2B, a pair of rectangular brush holders 7 are arranged on one surface of the base 9 so as to face each other at 180 ° intervals. The brush holder 7 and the base 9 are integrally molded by plastic. Each brush holder 7
As shown in FIG. 1, both ends are open to accommodate the brush 6, and the rear end of the brush 6 is elastically supported by being applied to an end portion 8a of a spring (spring spring) 8 described later. .

At a position adjacent to each brush holder 7 on the surface of the base 9,
The pillar 18 is formed, and the spring 8 is fitted to the pillar 18,
One end 8a is extended to one end (rear end) of the opening of the brush holder 7, and this spring end 8a supports the brush 6 while biasing the brush 6 toward the commutator 4. The column 18 is integrally molded with the base 9 by plastic.

At the tip of the brush holder 7, a part of the brush 6 projects,
A tongue-shaped projection 11 is integrally provided with the brush holder 7 at the rear end so as to project outward. A rectangular parallelepiped elastic body (insulating elastic member) 12 is inserted into the tongue-shaped projection 11.

The second cylindrical elastic body 17 is fixedly arranged at each corner on the surface of the base 9 opposite to the brush holder side. This cylindrical elastic body
The protrusion 17 is pressed into a protrusion 16 provided on the base 9 as shown in FIG.

When the 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 tip of the brush 6 facing and contacting the outer peripheral surface of the commutator 4. The elastic body 12 inserted and attached to the tongue-shaped projection 11 is fitted into the notch recess 15 provided at one end of the cylindrical yoke 14, and the second elastic member is provided between the base 9 and the inside of the end cover 3. A small flange for the end cover 3 while interposing the body 17
3a is fitted into the motor installation flange (large flange 24) on the housing 2 side, and the flanges 3a and 24 are screwed together. According to such mounting, the ridge pressure acts between the end cover 3 and the cylindrical yoke 14, and the elastic compression body
12,17 are properly compressed by this narrow pressure.

Specifically, the force from the cylindrical yoke 15 acts on the elastic body 12, and the force from the end cover 3 passes through the second elastic body 17, the base 9, the brush holder 7, and the tongue-shaped projection 11. The elastic body 12 is pressed against and fixed to the end surface of the cylindrical yoke 15 by acting as a result. The second elastic body 17 is sandwiched between the base 9 and the inside of the end cover 3.

Next, the external power supply connection of the brush 6 will be described.

As shown in FIG. 2 (a), a notch 7a is provided on one surface of the brush holder 7, a pair of notched groove projections (guide grooves) 21a, 21b are provided on one surface of the base 9, and a small portion of the end cover 3 is provided. Flange 3a
Small holes 23a, 23b and a projection guide 22 are formed in the.

Further, as shown in FIG. 1, the flange 24 of the housing 2
An external connection connector 25 is formed on the. Standard terminals 20a and 20b of external connection connectors are attached to the tips of the conductive wires (pigtails) 19a and 19b of each brush.

The standard terminals 20a, 20b and the electric conductors 19a, 19b are provided with a notch 7a provided in each brush holder 7, guide grooves 21a, 21b of the base 9, a ventilation window 3b provided in the end cover 3, a projection guide 22 and a small hole.
It is inserted and fixed in the external connection connector portion 25 through 23a and 23b. Connection to an external power source is possible via this external connection connector 25. In addition, on the commutator side of the base 9,
In order to prevent a short circuit between the conductive wires 19a, 19b and the commutator 4 after the brush holding assembly 10 is assembled, a protection guide 26 is arranged as shown in FIG.

According to this embodiment, the following effects are obtained.

First, the electric motor housing 2, the end cover 3, the brush holder 7, the base 9 and the like are made by plastic molding to reduce the weight, but the brush holder end 11 of the present embodiment is In place of the rigid plastic housing 2, a structure is adopted in which the end surface of a highly rigid iron cylindrical yoke 14 is pressed and fixed via an elastic body 12, and the base 9 surface closest to the holder 7 is provided with a second elastic body 17. Since it is pressure-contacted and fixed to the inner side of the end cover 3 via the brush, the sliding friction vibration generated between the brush 6 and the commutator 4 is generated at a position close to the vibration source of the brush 6
Is absorbed in the form of sandwiching. Therefore, the most effective vibration damping can be performed, and the vibration / noise suppression effect of the electric motor can be improved. Moreover, the elastic bodies 12 and 17 can be attached very easily, and the dimensional accuracy is not required to be as strict as in the conventional elastic body coating method, which is advantageous in terms of cost.

Secondly, the connection of the brush 6 to the external connection connector 25 is performed by the guide holes 21a and 21b provided in the base 9 and the end cover 3
Using the ventilation window 3b, the projection guide 22, the small holes 23a, 23b, etc., connect the standard terminals 20a, 20b provided at the tips of the conductive wires 19a, 19b to the respective connectors.
Assembling is easy because it can be directly inserted into 25. Further, the positive side and negative side standard terminals 20a and 20b and the conductive wires 19a and 19b.
Are separated from each other by the guide holes 21a and 21b provided in the base 9, the projection guide 22 of the end cover and the small holes 23a and 23b, so that the conductive wire is prevented from being twisted and insulated, and the reliability of the motor is improved. be able to.

Thirdly, since the holder 7 and the base 9 are integrally formed by plastic, the assembling work can be simplified. Conventionally, it takes time and effort to assemble the holder and base separately after assembling them, and since the connector, harness, etc. are used for the conductive wire connection from the brush to the external connection connector, There was a desire for simplification of sex.

〔The invention's effect〕

As described above, according to the present invention, it is possible to sufficiently meet the requirements of both plasticization (lightening) of the motor housing and the suppression of vibration and noise, and strictness in the dimensional control accuracy 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 description of drawings]

FIG. 1 is a partially cutaway sectional view showing an embodiment of the present invention, and FIG. 2 is an exploded perspective view of an end cover and a brush holding assembly used in the above embodiment. 2 ... Motor 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, 17 ... Second
Elastic body, 19a, 19b ... Conductive wire, 20a, 20b ... External connection terminal, 21a, 21b ... Guide hole, 22 ... Projection guide, 23a, 23b
...... Small hole, 24 ...... Flange, 25 ...... Connector for external connection.

Claims (4)

[Claims] 1. A small electric motor comprising a brush holder for accommodating and holding a brush, a rotor having a commutator in sliding contact with the brush, etc., and the brush holder on a base for supporting the holder together with the base. It is integrally molded by plastic, and the electric motor housing is also plastic molded, and a high-rigidity cylindrical yoke that forms a magnetic path of the electric motor is fixedly arranged on the inner periphery of the electric motor housing, and the end of the cylindrical holder is provided with the brush holder. A small electric motor, one end of which is pressed and fixed via an elastic body. 2. The base for supporting the holder according to claim 1, is arranged so as to face an inside of an end cover provided at one end of the electric motor housing, and a second elastic body is provided between the end cover and the base. A small electric motor with an intervening. 3. The electric motor housing according to claim 1 or 2, wherein a flange for electric motor installation is formed on the outer periphery of the electric motor housing, and an external connection connector is provided on the flange, while extending from the brush of the brush holder. An external connection terminal is attached to one end of the conductive wire, and the external connection terminal is passed through the guide hole provided in the base, the ventilation window provided in the end cover, the projection guide and the small hole to the inside of the external connection connector A small electric motor that is inserted and fixed in. 4. The guide hole provided in the base, the projection guide and the small hole provided in the end cover according to claim 3, wherein the plus side conductive wire and the minus side conductive wire of the conductive wire are separated from each other. A small electric motor that is inserted in this state to prevent twisting and insulation of these conductive wires.