JP2001182784A - Geared motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem, where when a motor axis is supported by a guide part provide in the case for maintaining proper meshing conditions of the worm and worm wheel in a geared motor, rotation oscillation of a motor is transmitted directly to the case to result in vibration and noise. SOLUTION: In the geared motor, a dummy gear 4 is meshed with a worm 2 so as to be arranged at the other side of a worm wheel 3 which is also meshed with the worm 2, and the worm 2 is supported by both the worm wheel 3 and the dummy gear 4. With such a constitution, even when a load is exerted on the worm wheel 3, proper meshing conditions will be maintained between the worm 2 and the worm wheel 3. Moreover, since the motor axis does not come into direct contact with the case, vibration which is transmitted to the case is reduced, thereby resulting in lower vibration and low noise geared motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geared motor, and more particularly, to a geared motor that changes the rotational power of a motor by a gear mechanism.

[0002]

2. Description of the Related Art Conventionally, a geared motor has been used as a drive device used for electrically adjusting a lumbar support such as a waist rest portion of a vehicle seat or a headrest. The geared motor is mainly composed of a motor that generates rotational power and a plurality of gears, and generates a larger torque by sequentially shifting the rotational power generated by the motor to a low speed through the plurality of gears. Can be done.

[0003] In a geared motor, the rotational power generated on the motor shaft is firstly transmitted through a worm, which is a cylindrical screw gear having one or more threads, which is fixed to the motor shaft. Conveyed to. The worm wheel is a gear having a rotating shaft perpendicular to the motor shaft and having a tooth surface meshing with the worm. The rotational power given to the worm wheel in this way is
If necessary, the gears are sequentially decelerated via other gears, and the rotation output of the geared motor is obtained.

FIG. 4 is a schematic partial sectional view of a conventional geared motor provided with a guide portion. The conventional geared motor includes a motor 1, a worm 2, a worm wheel 3, gears 5a, 5b, 5c, 5d, and a lower case 7.
And an upper case 8. The gear 5d and the upper case 8 are not shown in FIG. The lower case 7 has guide portions 9a and 9b. The main body of the motor 1 is fixed to the lower case 7, the worm 2 is mounted around the motor shaft, and both ends of the motor shaft are provided with guide portions 9a, 9b.
Are rotatably supported. The worm wheel 3 and the gears 5a, 5b, 5c, 5d are rotatably supported by the lower case 7 and the upper case 8, respectively.

[0005] The operation of the conventional geared motor configured as described above will be described.

[0006] When the motor 1 is driven, rotational power is applied to the motor shaft. As the motor shaft rotates, the worm 2 mounted on the motor shaft rotates, and the worm 2
The worm wheel 3 arranged in mesh with the rotation of the worm wheel rotates. The gear 5 a is arranged coaxially with the worm wheel 3, and rotates in conjunction with the worm wheel 3. Each of the gears 5b to 5c is a superimposed gear, and the gear 5b is disposed so as to mesh with the gear 5a.
Are arranged so as to mesh with the gear 5b, and the gear 5d is arranged so as to mesh with the gear 5c.
With this arrangement, the rotational power of the motor 1 is sequentially reduced through a plurality of gears, and finally the gear 5
transmitted to d. With such a gear mechanism, the geared motor can obtain reduced rotational power.

In FIG. 4, when a certain load is applied to the worm wheel 3 when the worm 2 and the worm wheel 3 are engaged with each other, the worm 2 exerts a force in the direction in which the worm wheel 3 is pushed by the worm wheel 3. receive. Therefore, the motor shaft receives a clockwise moment on the drawing with the contact point with the motor body as a fulcrum. On the other hand, in this conventional geared motor, guide portions 9a and 9b are provided in the lower case 7, and each supports the motor shaft so as not to be displaced in a direction perpendicular to the axial direction. Accordingly, the rotating shaft of the motor receives a reaction force from the guide portion 9a to cancel the clockwise moment. Thus, in the conventional geared motor, the worm 2 and the worm wheel 3
Had maintained an appropriate meshing state.

[0008]

However, in the conventional geared motor, the motor shaft is supported by the guide portions 9a and 9b provided on the lower case 7, so that
Although the proper engagement between the worm 2 and the worm wheel 3 could be maintained, since the motor shaft was in direct contact with the case, the rotational vibration of the motor was transmitted from the motor shaft to the case, the lumbar support vibrated, and the noise was reduced. There was a problem of becoming large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a geared motor which can maintain an appropriate meshing state between a worm and a worm wheel and has low vibration and low noise.

[0010]

A first aspect of the present invention is a geared motor that generates the rotational power of a motor by changing the speed by a gear mechanism. The motor has a rotating shaft, and is mounted around the rotating shaft of the motor. The worm includes a worm, a worm wheel that meshes with the worm, and a small gear that meshes only with the worm and that meshes with the worm wheel in a direction opposite to the rotation axis of the worm.

According to a second aspect of the present invention, in the first aspect, the point at which the small gear meshes with the worm is closer to the tip of the rotating shaft of the motor than the point at which the wall wheel meshes with the worm. .

According to a third aspect of the present invention, in the first aspect, there is provided a worm supporting portion which is fixed to a rotating shaft of the motor adjacent to at least one of both side surfaces of the worm.

According to a fourth aspect, in the third aspect, the worm support is fitted into a concave portion provided on a side surface of the worm.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic partial sectional view showing a configuration of a geared motor according to an embodiment of the present invention. FIG. 2 is a diagram showing the gear meshing relationship in the geared motor according to the embodiment of the present invention.

1 and 2, the geared motor includes a motor 1, a worm 2, and a worm wheel 3.
, A dummy gear 4, a worm stop 6a, 6b, gears 5a, 5b, 5c, 5d, a lower case 7, and an upper case 8.
And The main body of the motor 1 is fixedly supported by a lower case 7 and an upper case 8, and the worm 2 is fixedly supported on the motor shaft by worm stops 6a and 6b. The worm 2 is, as shown in FIG.
The side surface on the motor body side has a concave portion having the same shape as the worm stop 6b.
b and the worm stop 6a are fixed to the motor shaft in such a manner that both ends are supported. The worm wheel 3, the dummy gear 4, and the gears 5a, 5b, 5c, 5d are rotatably supported by the lower case 7 and the upper case 8, respectively.

In the following, specific examples of the constituent members, shapes, and installation methods of the respective constituent elements when carrying out this embodiment will be described.

The motor 1 is a DC brush motor having a rotating shaft diameter of 2 mm and a rotation speed of about 7,000 rpm. Worm 2 has a lead angle of 7 degrees, a module of 0.5, and an outer diameter of 5.56.
mm of polyacetal resin worm. The worm wheel 3 is made of polyacetal resin. The worm stops 6a and 6b are made of brass and have a thickness of 1.2 mm. The dummy gear 4 is made of polyacetal resin, has eight teeth, and has an outer diameter of 5.4 mm. The lower case 7 and the upper case 8 are both made of PBT (polybutylene terephthalate), and are fixedly supported by screws to fix and support the outer shell of the motor 1 and a plurality of gear shafts. The gear shaft of the dummy gear 4 is made of stainless steel and has a diameter of 2 mm. After being press-fitted into the lower case, it is loosely mounted on the upper case.

Hereinafter, the operation of the geared motor according to the embodiment of the present invention configured as described above will be described.

When the motor 1 is driven, rotational power is given to the motor shaft. When the motor shaft rotates, the worm 2 fixed to the motor shaft rotates, and the worm 2
The worm wheel 3 and the dummy gear 4 arranged so as to mesh with each other rotate accordingly. The gear 5 a is arranged coaxially with the worm wheel 3 and rotates in conjunction with the worm wheel 3. The gear 5b is arranged in mesh with the gear 5a, and the gear 5c is
The gear 5d is arranged in mesh with the gear 5c. With this arrangement, the rotational power of the motor 1 is finally transmitted to the gear 5d, and the rotational power becomes the rotational output of the geared motor.
In this way, the rotational speed of the motor, which was about 7,000 rpm, can be finally reduced to about 7 rpm. The dummy gears 4 are arranged independently without meshing with other gears, and do not transmit the rotational power given by the worm 2 to other gears.

The effect of providing the dummy gear 4 will be described below.

In FIG. 1, when a certain load is applied to the worm wheel 3 in the engagement between the worm 2 and the worm wheel 3, the worm 2 is moved from the worm wheel 3 to the worm wheel 3 with respect to the rotation center axis of the motor shaft. Subject to force in opposite direction. Therefore, the motor shaft receives a clockwise moment in FIG. 1 with the contact point with the motor body as a fulcrum. On the other hand, in the geared motor of the present embodiment, a dummy gear 4 is provided at a position opposite to the worm wheel 3 when viewed from the worm 2. Therefore, the motor shaft receives a reaction force from the dummy gear 4 via the worm 2 so as to cancel the clockwise moment. Thus, in the geared motor according to the present embodiment, it is possible to maintain an appropriate meshing state between the worm 2 and the worm wheel 3.

As described above, the use of the dummy gear 4 prevents the motor shaft from directly contacting the lower case 7 unlike the conventional geared motor shown in FIG. 4, and the vibration of the motor shaft is reduced by the dummy gear 4 and the gear shaft. , The vibration and noise transmitted to the case are reduced. Further, the dummy gear 4 may be arranged so as to mesh with the worm 11, and can be arranged independently of other gears, so that assembling is easy and design flexibility is high. Further, since the size of the gears may be small, it is effective for downsizing the geared motor.

The dummy gear 4 can be arranged at any position where the dummy gear 4 can mesh with the worm 2 from the opposite side of the worm wheel 3. However, a counterclockwise moment having the same magnitude as the above-described clockwise moment needs to be generated by the dummy gear 4. Therefore, the load applied to the dummy gear 4 may be smaller at a position farther from the fulcrum (the contact point between the motor body and the motor shaft), that is, at the distal end side of the motor shaft. This is preferable in terms of scale.

Next, the effect of providing the worm stops 6a and 6b will be described. Generally, warm 2
The worm made of resin is used, but since the worm made of resin has a small holding force on the motor shaft, there is a possibility that the worm may be displaced in the thrust direction or the rotation direction due to a reaction force or the like received from the worm wheel 3. . Then, there arises a problem that an appropriate meshing state between the worm 2 and the worm wheel 3 is lost, or the worm 2 moves toward the distal end of the motor shaft and the worm 2 comes into contact with the case to generate a large vibration in the case. . Therefore, it is necessary to fix and support the worm 2 so as not to shift in the thrust direction and the rotation direction with respect to the motor shaft.

In this embodiment, two worm stops 6
a, 6b are fixed to the motor shaft so as to sandwich the worm 2 from both sides. Since both the worm stops 6a and 6b are made of metal, the holding force on the motor shaft is large. Therefore, by disposing the two worm stops 6a and 6b in this manner, the worm 2 is prevented from shifting in the thrust direction. Further, as shown in FIG. 3, a recess having the same shape as the worm stop 6b is provided on a side surface of the worm 2 on the side of the motor shaft main body, and the worm stop 6b is fixed to the motor shaft by being fitted into the recess. This prevents the worm 2 from shifting in the rotational direction with respect to the motor shaft.

As described above, according to the present embodiment, a proper engagement between the worm and the worm wheel can be maintained by supporting the motor rotation shaft by the worm wheel and the dummy gear. Furthermore, since the motor shaft does not directly contact the case, the rotational vibration of the motor transmitted to the case is reduced, and a geared motor with lower vibration and lower noise can be realized.

[0027]

According to the first aspect of the invention, the rotating shaft of the motor is supported from both sides by the worm wheel and the small gear, so that a proper meshing state between the worm and the worm wheel can be maintained. Since the motor does not directly contact the outer periphery of the geared motor, vibration of the rotating shaft of the motor can be prevented from being directly transmitted to the outer periphery of the geared motor, and a geared motor with lower vibration and lower noise can be realized.

According to the second aspect of the present invention, by engaging the small gear with the worm on the motor rotating shaft tip side of the worm wheel, the moment received by the rotating shaft of the motor from the worm wheel can be eliminated with a smaller force. Therefore, the load on the small gear can be reduced, the reliability can be improved, and the small gear can have a simpler configuration.

According to the third aspect of the invention, by providing the support portion so as to be in contact with the side surface of the worm, it is possible to prevent the worm from shifting in the thrust direction due to a reaction force or the like from the worm wheel.

According to the fourth aspect, by fitting the worm support into the recess on the side surface of the worm, it is possible to prevent the worm from rotating in the rotational direction with respect to the rotation axis of the motor due to a reaction force from the worm wheel or the like. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic partial sectional view showing a configuration of a geared motor according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a meshing relationship of gears in the geared motor according to the embodiment of the present invention.

FIG. 3 is a diagram showing shapes and positional relationships of a worm and a worm stop according to the embodiment of the present invention.

FIG. 4 is a schematic partial sectional view showing a configuration of a conventional geared motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Worm 3 ... Worm wheel 4 ... Dummy gear 5a, 5b, 5c, 5d ... Gear 6a, 6b ... Warm stop 7 ... Lower case 8 ... Upper case

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J009 DA11 EA05 EA06 EA11 EA19 EA25 EA32 EB30 FA14 5H607 AA04 BB04 BB09 DD03 EE31 EE32 EE36 JJ05 KK07

Claims (4)

[Claims] 1. A geared motor that generates a rotational power of a motor by changing the speed by a gear mechanism, comprising: a motor having a rotating shaft; a worm mounted around the rotating shaft of the motor; and a worm meshing with the worm. A geared motor comprising: a wheel; and a small gear that meshes only with the worm and meshes with the worm wheel from a direction opposite to the worm wheel. 2. The motor according to claim 1, wherein the point at which the small gear meshes with the worm is closer to the distal end of the rotating shaft of the motor than a point at which the wall wheel meshes with the worm. Geared motor as described. 3. The geared motor according to claim 1, further comprising a worm supporting portion fixed to a rotating shaft of the motor adjacent to at least one of both side surfaces of the worm. 4. The worm support portion is fitted in a concave portion provided on a side surface of the worm.
The geared motor according to claim 3.