JPH10322961A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve quality as well as reduce manufacturing cost. SOLUTION: A rotary shaft whereon an armature and a commutator are pivoted, is borne rotatably by an inner ring 6a of a baring 6. A cover 3 which forms a housing together with a case is made of plate material having elasticity and is provided with a bottomed cylindrical retainer 5. An outer ring 6b of the bearing 6 is set in a free condition in a circular part 5a of the retainer 5 and is also pressurized in the direction of an arrow A by a bottom part 5c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor, and more particularly to a bearing structure for rotatably supporting a rotating shaft of the electric motor.

[0002]

2. Description of the Related Art As shown in FIGS. 6 and 7, an electric motor 1 of this type generally has a bottomed cylindrical case 2 and a lid 2.
A winding 12 is connected to a rotating shaft 8 rotatably supported via bearings 6 and 7 in a housing 4 composed of a rotating shaft 8 and an armature 9 and a terminal 11 mounted on the rotating shaft 8. And a plurality of magnets 13 fixed to the inner peripheral surface of the case 2 so as to surround the outer periphery of the armature 9. The power supply brush 1 further includes two power supply brushes 14 held by a holder 15 and slidably contacting the outer peripheral surface of the commutator 10.
The direction of the current supplied to the winding 12 of the armature 9 is switched by mechanical sliding contact between the commutator 4 and the commutator 10.

In the electric motor 1 configured as described above,
In order to suppress the rotational vibration of the armature 9 attached to the rotating shaft 8 rotatably supported by the bearings 6 and 7, a so-called preload is applied to the rotating shaft 8 at all times in the direction of arrow A in the drawing. . This will be described in more detail with reference to FIG.
At the center of the lid 20, a holding portion 21 formed in a shallow dish shape is recessed, and an outer ring 6b of the bearing 6 is loosely fitted into an annular portion 21a of the holding portion 21. ing. The inner ring 6 a of the bearing 6 is mounted on the output end 8 a of the rotating shaft 8.

[0006] In FIG. 6, the other end 8 b of the rotating shaft 8 is axially mounted on an inner ring 7 a of a bearing 7, and the outer ring 7
b is a bottomed cylindrical holding portion 2a recessed in the bottom plate of the case 2.
The rotating shaft 8 is rotatably supported by the holding parts 21 and 2a via bearings 6 and 7.
In the state where the load is not applied in the axial direction as described above, when the rotating shaft 8 rotates under the influence of the clearance inside the bearing, the rotational vibration increases. Therefore, in order to suppress this rotational vibration, the outer ring 6 b of the bearing 6 on the output side and the bottom 21
A preload in the direction of arrow A is applied to the rotating shaft 8 via the bearing 6 by the washer 22.

[0005]

However, in the above-mentioned conventional electric motor, since the washer 22 is used for applying the preload in the direction of arrow A, the washer 22 is forgotten to be assembled or dropped during assembly. Alternatively, there has been a problem of a product defect due to a defective assembly. In addition, the number of components has increased due to the addition of the washer 22, and the manufacturing cost has also increased.

The present invention has been made in view of the above-described conventional problems, and has as its object to provide an electric motor that improves quality and reduces manufacturing costs.

[0007]

In order to achieve the above object, an electric motor according to the present invention is configured such that both ends of a rotary shaft are rotatable on a housing via a pair of bearings, and an outer ring of at least one of the bearings is provided. In an electric motor supported movably in the axial direction of a rotating shaft, a lid constituting the housing is formed of an elastic plate material, and one of the pair of bearings is axially moved by the elasticity of the lid. In this case, the one movably supported is urged toward the other side. Therefore, the rotating shaft is preloaded by the lid via the bearing.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1A is a cross-sectional view of the electric motor according to the present invention, FIG. 1B is a side view, and FIG. In these figures, the same or equivalent members described in the prior art shown in FIGS. 6 and 7 are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate. The feature of the present invention lies in that a preload in the direction of arrow A is applied to the outer ring 6b of the bearing 6 by the elasticity of the lid 3 itself.

That is, the lid 3 is entirely formed of an elastic plate material, and a shallow dish-shaped holding portion 5 is provided in the center thereof. A plurality of cutouts 5b are formed at the base of the annular portion 5a of the holding portion 5 at equal angular positions in the circumferential direction, and the annular portion 5a is formed so that the outer ring 6b of the bearing 6 is fitted. Have been.

In such a configuration, the outer race 6 of the bearing 6
The outer ring 6b is fitted into the annular portion 5a by attaching the lid 3 to the case 2 by screws 17 so that the annular portion 5a of the holding portion 5 of the lid 3 is engaged with the outer ring 6b.
Are supported by the holding portion 5 so as to be movable in the axial direction of the rotating shaft 8. When the cover 3 is attached to the case 2, when the bottom 5 c of the holding portion 5 contacts the outer ring 6 b of the bearing 6, the cover 3
Annular portion 5a such that a gap is formed between
Height is set. Therefore, cover 3 is screwed 1
7, the bottom portion 5c of the holding portion 5 presses the outer ring 6b in the direction of arrow A by the elasticity of the lid 3, so that a preload in the direction of arrow A is applied to the rotating shaft 8 via the bearing 6. Can be At this time, the notch 5b provided at the base of the annular portion 5a functions to reduce the elasticity of the lid 3, so that the outer ring 7b of the other bearing 7 is
There is no need to be pressed against the bottom of a more strongly than necessary, and there is no hindrance to the rotation of the rotating shaft 8.

At the same time, the bearing 6 is provided in the annular portion 5a of the holding portion 5.
Even when the outer ring 6b is fitted in a static engagement state, the notch 5b can provide a resilient force, so that there is no problem in energizing the rotating shaft 8 in the axial direction. In this manner, the notch 5b can absorb errors and variations in manufacturing the holding portion 5 of the lid 3. The urging force of the lid 3 can be adjusted by changing the outer dimensions or the number of the notches 5b.

FIG. 3 is a sectional view of a main part showing a second embodiment of the present invention. In the second embodiment, the outer ring 6b of the bearing 6 is movably supported in the axial direction of the rotating shaft 8 by the concave portion 15a having a circular cross section formed on the end face of the holder 15. The inner diameter of the annular portion 5a of the holding portion 5 is formed slightly larger than the outer diameter of the outer ring 6b of the bearing 6, and a gap is formed between the inner peripheral surface of the annular portion 5a and the outer peripheral surface of the outer ring 6b. I have. In the second embodiment, the holder 15
Thus, the bearing 6 is movably supported in the axial direction of the rotary shaft 8, and the lid 3 has a function of only applying a preload in the direction of arrow A to the bearing 6.

As described above, the function of supporting the bearing 6 movably in the axial direction of the rotary shaft 8 and the function of applying a preload are shared between the holder 15 and the lid 3, so that the holding portion of the lid 3 is held. There is no need to fit the annular portion 5 a of 5 into the outer ring 6 b of the bearing 6. For this reason, when attaching the lid 3 to the case 2, it is not necessary to adjust the alignment with the bearing 6, and a gap is formed between the inner peripheral surface of the annular portion 5 a and the outer peripheral surface of the outer ring 6 b. Therefore, even if a manufacturing error occurs, the outer ring 6b is not tightly fitted by the annular portion 5a.

FIG. 4 is a sectional view of a main part showing a third embodiment of the present invention. In the third embodiment, in the second embodiment described above, a plurality of protrusions 5d are provided on the bottom 5c of the holding portion 5 around the rotation shaft 8 at equal angular intervals in the circumferential direction. The outer ring 6b of the bearing 6 is pressed in the direction of arrow A via these projections 5d. Since the pressing is performed via the protrusion 5d, there is no variation in the pressing force, and a constant preload is reliably applied.

FIG. 5 is a sectional view of a main part showing a fourth embodiment of the present invention. In the fourth embodiment, the lid 3
A plurality of projections 3a are provided around the rotation shaft 8 at equal intervals in the circumferential direction without providing the holding portion 5, and the outer ring 6b of the bearing 6 is moved through the projections 3a in the direction of arrow A. Is pressed. Since it is not necessary to form the holding portion 5 in this manner, the shape of the lid 3 is simplified, and thus the manufacturing is facilitated. In the third and fourth embodiments described above, the projections 5d and 3a are divided into a plurality of parts. However, the present invention is not limited to this. May be provided.

In the present embodiment, the electric motor 1 is a DC motor. However, the present invention is not limited to this, and can be applied to an AC motor.

[0017]

As described above, according to the present invention, the problem of product failure due to forgetting to assemble a washer, dropping out during assembling, or improper assembling does not occur as in the prior art. improves. Also, the number of parts is reduced, and the manufacturing cost is reduced.

Further, according to the second aspect, a certain preload is reliably applied by the projection.

[Brief description of the drawings]

FIG. 1 shows an electric motor according to the present invention, in which (a) is a cross-sectional view and (b) is a side view.

FIG. 2 is an enlarged sectional view showing a main part of the electric motor according to the present invention.

FIG. 3 is an enlarged sectional view showing a main part of an electric motor according to a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view showing a main part of an electric motor according to a third embodiment of the present invention.

FIG. 5 is an enlarged sectional view showing a main part of an electric motor according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view of a conventional electric motor.

FIG. 7 is an enlarged sectional view showing a main part of a conventional electric motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Case, 2a, 5 ... Holding part, 3 ...
Lid body, 3a, 5b projection, 5a annular part, 6, 7 bearing, 6a, 7a inner ring, 6b, 7b outer ring, 8 rotary shaft, 9 armature, 10 commutator, 12 winding ,
13 ... magnet, 14 ... power supply brush, 15 ... holder.

Claims (2)

[Claims] 1. An electric motor in which both ends of a rotating shaft are rotatably supported by a housing via a pair of bearings and an outer ring of at least one of the bearings is movably supported in the axial direction of the rotating shaft. The lid is formed of an elastic plate material, and the elasticity of the lid urges one of the pair of bearings in the axial direction and the other movably supported to the other side. Electric motor. 2. The electric motor according to claim 1, wherein a projection is provided on the lid, and a bearing is urged through the projection.