JPH065361U - Electric motor with worm gear - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an electric motor with a worm gear, in which the sliding portion has little dimensional change and whose characteristics are improved and which has good durability. [Structure] By providing a bush 4 made of an iron plate on the sliding portion between the protrusion 3a at the center of the gear case 3 and the inner diameter of the worm wheel 2, the dimensional change is small with respect to the load and thermal stress applied to the worm wheel 2. In addition, a stable friction coefficient can be obtained. Therefore, it is possible to improve the characteristics and the durability with less variation in the characteristics.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electric motor with a worm gear used for electric parts for automobiles.

[0002]

[Prior art]

 In recent years, there has been a strong demand for improvement in durability of worm gear electric motors used for electric parts for automobiles.

A conventional electric motor with a worm gear will be described below with reference to FIGS. 3 and 4. 3 is an axial sectional view thereof, and FIG. 4 is an XX sectional view of FIG. In FIG. 4, the worm wheel 11 is supported on the outer circumference of a bearing portion 12 a formed integrally with the gear case 12. A torque transmission plate 13 is supported by an output shaft bearing 14 which is press-fitted and fixed to the gear case 12. The output shaft 15 is fixed by a retaining ring 16. A gear cover 17 covers the opening of the gear case 12. Reference numeral 19a is a shock absorber.

The operation of the worm gear electric motor configured as described above will be described below.

Torque is transmitted to a worm 19 formed at one end of the motor shaft 18 and a worm wheel 11 meshing with the worm 19, and the worm wheel 11 is supported by a bearing portion 12 a of a gear case 12 and rotates. . At this time, the inner circumference of the worm wheel 11 and the bearing portion 12a of the gear case always slide in the rotating direction, and frictional heat is generated by receiving a load.

[0006]

[Problems to be solved by the device]

 In such a conventional configuration, since both the worm wheel and the gear case bearing are made of synthetic resin, the load on the worm wheel and the thermal stress generated by the sliding due to the rotation cause the bearing and the worm. The sliding clearance with the inner circumference of the wheel is not stable, the friction coefficient becomes unstable, and the durability of the worm wheel deteriorates due to fluctuations in the output shaft torque and wear of the sliding part, resulting in reduced durability. Had.

The present invention solves the above problems by suppressing fluctuations in the friction coefficient of the worm wheel and the bearing portion that supports the worm wheel, suppressing rattling and wear deterioration of the support portion of the worm wheel, and durability with little variation in characteristics. It is intended to provide an electric motor with a worm gear with improved performance.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention includes a bush made of an iron plate between a protrusion at the center of a gear case and an inner diameter of a worm wheel that slides on the outer periphery thereof.

[0009]

[Action]

 Since the present invention employs a metal bush on the sliding surface with the above configuration, the dimensional change of the bearing part is small even with heat stress, and the clearance between the worm wheel and the sliding part is stable. I can keep it. Also, a stable friction coefficient can be obtained without wear.

[0010]

【Example】

 An electric motor with a worm gear according to an embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, 1 is a worm formed on a motor shaft, 2 is a worm wheel made of synthetic resin that meshes with the worm, and 3 is a gear case. A bush 4 made of an iron plate is inserted into the protruding portion 3a at the center of the gear case, and its outer diameter constitutes a bearing portion. An output shaft bearing 5 is press-fitted and fixed to the inner diameter of the center of the gear case 3. 6 is a shock absorber, and 7 is a torque transmission plate, which is fixed to an output shaft 8 supported by an output shaft bearing 5 by a retaining ring 9. The other configurations are the same as those of the conventional example and are omitted.

FIG. 2A shows a perspective view of the bush 4, and FIG. 2B shows a side sectional view thereof. As described above, according to the present embodiment, since the bush 4 formed of the iron plate is inserted between the sliding portion between the protrusion 3a of the gear case 3 and the inner diameter of the worm wheel 2, the worm wheel 2 has Since the bearing part is made of metal against the applied load and heat stress, the dimensions do not change, and the clearance between the worm wheel and the sliding part can be maintained in a stable state. Further, since the sliding portion is made of metal, it is possible to obtain a stable friction coefficient without abrasion. Therefore, it is possible to improve the characteristics and extend the durability with less variation in characteristics.

[0013]

[Effect of device]

 As is clear from the above description, in the present invention, since the bush formed of an iron plate is inserted in the sliding portion, the friction coefficient of the worm wheel sliding portion is stabilized and the load applied to the worm wheel is stabilized. By stabilizing the clearance of the sliding portion against heat stress, it is possible to provide a worm-gear electric motor with improved durability and less variation in characteristics.

[Brief description of drawings]

FIG. 1 is a front sectional view of an electric motor with a worm gear according to an embodiment of the present invention.

FIG. 2A is a perspective view of a bush included in the electric motor with a worm gear according to an embodiment of the present invention. FIG. 2B is a side sectional view of FIG.

FIG. 3 is an axial sectional view of a conventional worm gear motor.

4 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 1, 19 Worm 2, 11 Worm wheel 3, 12 Gear case 3a, 12a Projection part 4 Bushing 5, 14 Output shaft bearing 6, 19a Damper 7,13 Torque transmission plate 8,15 Output shaft 9,16 Stop ring 10,17 Gear cover 18 Motor shaft 20 Commutator 21 Brush 22 Winding 23 Magnet 24 Frame 25 Lead wire

Claims (1)

[Scope of utility model registration request] 1. A protrusion at the center of a gear case made of resin,
Between the inner diameter of the worm wheel that slides on its outer circumference,
Electric motor with worm gear equipped with metal bush.