JPH0626053Y2 - Bearing structure for small electric motors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a bearing structure for a small electric motor which supports a rotor shaft protruding toward a commutator by an oil-impregnated bearing fixed to a housing.

“Prior Art” Since the bearing and commutator are close to each other in a small electric motor, it is necessary to take measures to prevent oil from the bearing from adhering to the commutator.

JP-B-57-21493 and JP-B-63-249.
Japanese Unexamined Patent Publication No. 57-57 discloses a bearing structure in which an oil-impregnated bearing is used to support the rotor shaft protruding toward the commutator side.

[Problems to be Solved by the Invention] However, in the bearing structure disclosed in Japanese Utility Model Publication No. 57-21493, the frame is provided between the disk-shaped spacer washer abutting the end face of the commutator and the oil-impregnated bearing end face. A non-contact gap is formed so that the inner end surface of the oil-impregnated bearing and the spacer washer do not come into contact with each other by interposing a plate-shaped pressing spring fixedly fixed to the above and a holding spring between the pressing spring and the frame. It is a thing. The holding spring presses the end face of the commutator through the spacer washer by the holding spring. Therefore, there is a problem that a load is applied to the rotation of the rotor shaft. Further, there is a problem that the position of the oil-impregnated bearing is separated from the commutator due to the non-contact gap, which is disadvantageous in preventing vibration of the rotating portion and the dimension in the rotor axial direction becomes long.

On the other hand, the one disclosed in Japanese Utility Model Laid-Open No. 63-24957 discloses a synthetic resin-made ring-shaped protrusion having an L-shaped cross-section protruding between the oil-impregnated bearing and the commutator toward the rotor shaft. By providing it integrally with the brush holder, it is possible to prevent the oil flowing out from the oil-impregnated bearing, and because the brush holder and the protruding part are an integrally molded product of synthetic resin, the parts price is high and the oil-impregnated bearing and commutator are There is a problem in that it is disadvantageous in preventing the vibration of the rotating part due to the distance.

Further, in any of the above cases, there is almost no problem when the motor shaft is used in a horizontal posture, but when the motor shaft is used with the commutator side facing up and the shaft is in a vertical posture, the oil impregnated bearing is rotated. There is a problem that a part of the sucked oil flows downward along the shaft without being shaken off and adheres to the commutator.

The present invention has been made to solve the above problems, and provides a bearing structure that prevents unnecessary oil from being sucked out from an oil-impregnated bearing and does not cause a problem even when the motor shaft is used in a vertical direction. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the bearing structure of the small electric motor of the present invention is a small electric motor supporting the shaft of the rotor protruding toward the commutator by an oil-impregnated bearing fixed to the housing. In the bearing structure, a thrust washer that contacts the end surface of the oil-impregnated bearing is provided on the shaft, the end surface member of the rotor can be abutted on the thrust washer, and a protrusion formed on the outer periphery of the thrust washer is provided in the housing. It is characterized in that it is engaged with and is provided with a detent.

[Operation] In the bearing structure configured as described above, the thrust washer is stationary and is stationary. Therefore, sliding does not occur between the oil-impregnated bearing and the end surface of the oil-impregnated bearing, so that the impregnated oil is not sucked out.

Further, the oil sucked out from the hole of the oil-impregnated bearing due to the sliding contact with the shaft is absorbed into the oil-impregnated bearing again at the end portion and the end surface of the hole by the capillary phenomenon.

[Embodiment] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a vertical sectional view showing a DC motor according to the present invention.

This electric motor is a small direct current motor mounted on an automobile. Upper and lower case bodies 2 and 3 made of metal are fitted on the upper and lower sides of a housing 1 made of resin, and constitute outer shells of a motor. A speed reducer 4 is installed in a space above the resin housing 1, and a stator 5, a rotor 6 and the like of a DC machine are installed in a space below the resin housing 1.

A cylindrical permanent magnet 5 is fitted and fixed to the inner peripheral surface of the lower case body 3 to form a stator 5 of the motor. The permanent magnets 5 are magnetized in the thickness direction, and the magnetized directions alternate on the circumference. An oil-impregnated bearing 8 that supports the shaft 7 of the rotor 6 is fixed to the center of the bottom of the lower case body 3.

As shown in FIG. 2, the resin housing 1 includes brush holders 11 and 11 ', and spring springs 12 and 12' for pressing brushes.
Shaft 13, 13 ', PTC thermistor 1
4, groove portions 15 for accommodating four, box portions 17, 17 'for fixing wiring such as pigtails 16, 16', and groove portions 18, 19 for locking the thrust washer 30 are integrally formed. FIG. 2 is a view taken along the line II-II in FIG. 1 with the lower case body 3 and the rotor 6 removed. Wirings such as the pigtail 16 and brushes are omitted in FIG.

A spherical oil-impregnated bearing 20 for supporting the shaft 7 of the rotor 6 is fixed to the central portion of the resin housing 1.
Further, a shaft 21 for supporting a gear is vertically installed on the upper surface of the resin housing 1.

A bearing 23 for supporting the output shaft 9 is provided in the center of the upper case body 2.
Is fixed. These bearings 8, 20, and 23 are all made of sintered metal impregnated with lubricating oil.

The spherical oil-impregnated bearing 20 in the central portion of the resin housing 1 and the oil-impregnated bearing 8 of the lower case body 3 rotatably support the rotor 6 shown in FIG. The rotor 6 includes an armature 25 and a commutator 26, and is fixed to the shaft 7. Commutator 2
A collar 27 as shown in FIG. 4 is fixed to the end face of 6,
It forms an end face member of the rotor 6.

A thrust washer 30 according to the present invention is disposed between the collar 27 forming the end surface of the rotor 6 and the end surface of the spherical oil-impregnated bearing 20. As shown in FIG. 5, the thrust washer 30 has a disc shape having two protrusions 30A and 30B on the left and right sides, and is made of fluororesin. The thrust washer 30 is disposed in close contact with the end surface of the spherical oil-impregnated bearing 20, and the protrusions 30A and 30B thereof are inserted into and engaged with the grooves 18 and 19 of the resin housing 1, and are locked to prevent rotation.

In the rotor 6, the end face of the collar 27 is the thrust washer 30.
The lower end of the shaft 7 is slidably contacted with the lower case body 3 to regulate the axial position thereof. Since the thrust force is not applied to the shaft 7 from the load, the thrust load supported by the thrust washer 30 is small, and it can be sufficiently supported by the self-lubricating property of the fluororesin.

Further, the thrust washer 30 may be a metal plate having a lubricating coating such as molybdenum formed on its surface.

A pinion 41 is fixed to the tip of the shaft 7 protruding upward from the resin housing 1, and the rotation is transmitted to the gear 43 of the output shaft 9 via the idle gear 42 supported by the upright shaft 21. It is designed to be driven to decelerate and rotate.

The operation will be described. When the motor is energized and the rotor 6 rotates, the collar 27 forming the end face member of the rotor 6 may come into sliding contact with the thrust washer 30. But,
Since the thrust washer 30 is locked to the resin housing 1 by the protrusions 30A and 30B, the thrust washer 30 does not rotate with the shaft 7 and is stationary. Therefore, there is no sliding contact with the end surface of the spherical oil-impregnated bearing 20, and oil is not sucked out from the end surface. In addition, the shaft 7 and the spherical oil-impregnated bearing 20
Even if a part of the oil sucked out by sliding contact with the oil flows downward, it is sucked into the gap between the end surface of the spherical oil-impregnated bearing 20 and the thrust washer 30 by the capillary phenomenon, and is absorbed inside the spherical oil-impregnated bearing 20 again. It Therefore, it is possible to prevent oil from adhering to the surface of the commutator 26.

Moreover, since the thrust washer 30 is locked to the resin housing 1, the thrust washer 3 is rotated as the shaft rotates.
Zero does not cause non-uniform vibration and does not produce abnormal noise.

[Advantage of Invention] The present invention, which has the above-described structure and includes the thrust washer locked to prevent rotation, sucks out the impregnated oil without sliding between it and the end surface of the oil-impregnated bearing. In addition, the oil sucked out from the hole of the oil-impregnated bearing due to the sliding contact with the shaft is absorbed inside the oil-impregnated bearing again at the end and end face of the hole by the capillary phenomenon, so the number of parts is not increased. With a simple structure, it is possible to prevent unnecessary oil from being sucked out from the oil-impregnated bearing.
Therefore, even when the motor shaft is set in the vertical direction and the commutator is used in a posture such that it is below the bearing, there is an effect that a problem due to oil adhesion does not occur.

Further, since the oil-impregnated bearing can be arranged closer to the commutator, there is an advantage that it becomes easy to prevent the shaft from swinging.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a longitudinal sectional view of a DC motor, FIG. 2 is a view taken along the line II-II of FIG. 1, FIG. 3 is a front view showing a rotor, and FIG. FIG. 5 is a plan view and a sectional view showing a collar, and FIG. 5 is a plan view and a sectional view showing a thrust washer. 1 ... Resin housing, 4 ... Reduction gear, 6 ... Rotor, 7 ...
Shaft, 9 ... Output shaft, 8, 20 ... Oil-impregnated bearing, 26 ... Commutator,
27 ... Collar (end member), 30 ... Thrust washer,
30A, 30B ... Projections.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Shown 63-24957 (JP, U) Shown 53-1104 (JP, U) Shown 57-21493 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A bearing structure of a small electric motor which supports a shaft of a rotor protruding toward a commutator by an oil-impregnated bearing fixed to a housing, wherein a thrust washer in contact with an end face of the oil-impregnated bearing is provided on the shaft, A bearing structure for a small electric motor, characterized in that an end face member of the rotor can be brought into contact with a thrust washer, and a protrusion formed on the outer periphery of the thrust washer is engaged with a housing to prevent rotation.