JPH10174352A - Motor's slip off preventive structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor's slip off preventive structure by which the slip off of the rotor of a motor is performed without fail without the number of parts increasing, and decides, downsizing, thinning, weight reduction, and cost down can be made. SOLUTION: An upper oil retaining metal bearing 1 is fitted at the upper inner surface of a bearing bush 3 fixed to a substrate 5. On the other hand, a lower oil retaining metal bearing 2 is fitted under the shaft 4 attached to a rotor 6. If the shaft 4 and the rotor 6 seek to slip off upward, the topside of the lower oil retaining metal bearing 2 hits on the down side of the upper oil retaining metal bearing 1, and the slip off more than it is restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor retaining structure having a shaft pivotally supported by a bearing bush via a bearing and having a rotor fixed thereto.

[0002]

2. Description of the Related Art Referring to FIG. 5, a general structure of a motor generally used in the related art and a structure for preventing the motor from coming off will be described. A cylindrical bearing bush 3c is fixed to the substrate 5.
The shaft 4c is pivotally supported by the bearing bush 3c via the upper bearing 1c and the lower bearing 2c. Shaft 4
The rotor 6 for fixing the rotor magnet 7 to the inner surface is fitted to c. In addition, the rotor 6 is thrust supported by the upper bearing 1c via the washer 8. On the other hand, the stator 9 is fixed to the outer periphery of the bearing bush 3c. The stator 9 is arranged to face the rotor magnet 7 with an appropriate gap 10 therebetween. With the above structure, when the stator 9 is energized, the shaft 4 c and the rotor 6 rotate by the magnetic force between the stator 9 and the rotor magnet 7.

The lower end of the shaft 4c protrudes from the lower end of the lower bearing 2c, and a retaining bush 12 on which a washer 11 is mounted is fixed to the protruding portion. Shaft 4c
Is prevented by the contact of the washer 11 of the retaining bush 12 with the lower surface of the lower bearing 2c.

[0004] On the other hand, there are a number of known techniques relating to a motor retaining structure. For example, Japanese Utility Model Laid-Open No. 55-1031
3 and JP-A-6-186451. A "turntable driving motor" disclosed in Japanese Utility Model Laid-Open Publication No. 55-10313 discloses a plate-like flange (8) fixed to a base (1) for holding and rotating a peripheral flange (4) of a rotor cover (3). This restrains the child cover (3) from moving beyond a predetermined range. On the other hand, a "polygon scanner motor" disclosed in Japanese Patent Application Laid-Open No. Hei 6-186492 holds a rotor (5) side by a flat stopper (8) fixed to a base plate (7), and the axis of the rotor (5). This restricts the movement in the direction.

[0005]

Since the retaining structure of the conventional motor shown in FIG. 5 is a structure in which the retaining bush 12 and the like are fixed to the shaft 4c as described above, the shaft length of the shaft 4c is long. As a result, the motor becomes larger. Further, since the shaft length of the shaft 4c is long, the bending rigidity against external force acting on the shaft at the time of rotation decreases, and when the diameter is small, smooth rotation cannot be obtained, and the outside diameter of the shaft needs to be increased. Only the weight increases. Further, there is a problem in that separate parts such as the retaining bush 12 and the washer 11 are required, so that the cost is increased, the number of assembling steps is increased, and the weight is increased.

On the other hand, each of the above-mentioned known techniques has its own characteristics. However, each of them requires a separate part for retaining the parts, which results in a complicated structure, an increase in weight and an increase in cost. There is a point.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and secures the stopper without increasing the number of parts, and can be reduced in size, thickness, and weight, and the shaft and the rotor can be rotated stably. It is an object of the present invention to provide a motor retaining structure that can be removed.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above objects, the present invention provides a fixed vertical cylindrical bearing bush, and is pivotally supported inside the bearing bush via a pair of bearings. A shaft, a rotor provided on a portion of the shaft protruding above the bearing bush, and a stator fixed to the outside of the bearing bush and opposed to a rotor magnet fixed to the rotor with an appropriate gap therebetween. The bearing includes an upper oil-impregnated metal bearing and a lower oil-impregnated metal bearing. The upper oil-impregnated metal bearing is fixed to the bearing bush and rotatably supports the shaft. The bearing bush is fixed to the side to relatively rotate and support the bearing bush. Further, a stepped portion is formed on an inner surface of the bearing bush so as to project into a space between the upper oil-impregnated metal bearing and the lower oil-impregnated metal bearing.
Further, a thrust receiver is provided on a lower end surface of the bearing bush, and a lower end of the shaft is supported by the thrust receiver in a thrust manner.

The shaft is pivotally supported on the bearing bush via the upper oil-impregnated metal bearing and the lower oil-impregnated metal bearing, and does not need to be provided with a projection on the lower side. When the shaft tries to escape upward, the upper surface of the lower oil-impregnated metal bearing fixed to the shaft comes into contact with the lower surface of the lower oil-impregnated metal bearing. Since the upper oil-impregnated metal bearing is fixed to the bearing bush, the shaft cannot move further in the axial direction and is prevented from falling off. Also, by forming a stepped portion in the middle of the bearing bush, even if the shaft tries to come out upward, the lower oil-impregnated metal bearing abuts the stepped portion and the shaft is prevented from coming off. As described above, the present invention does not require a special component for retaining, so that the size and thickness can be reduced, and the cost and weight can be reduced.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a micromotor retaining structure according to an embodiment of the present invention.
FIG. 1 is an axial sectional view showing the entire structure of a micromotor having a retaining structure according to the present invention. The cylindrical bearing bush 3 is fixed to the substrate 5 by caulking or the like. The upper oil-impregnated metal bearing 1 is fitted on the upper side of the inner surface of the bearing bush 3. The shaft 4 faces the inner surface of the upper oil-impregnated metal bearing 1 via a small gap, and is rotatably supported by the metal bearing 1. The lower oil-impregnated metal bearing 2 is fitted to the lower outer peripheral surface of the shaft 4. A minute gap is formed between the outer surface of the lower oil-impregnated metal bearing 2 and the inner surface of the bearing bush 3, and the shaft 4 is rotatably supported on the inner surface of the bearing bush 3 via the metal bearing 2. Further, a space 15 having an appropriate space is formed between the lower surface of the upper oil-impregnated metal bearing 1 and the upper surface of the lower oil-impregnated metal bearing 2.

On the other hand, a thrust receiver 14 is fitted below the inner surface of the bearing bush 3 so as to close the lower surface opening of the bearing bush 3, and a wear-resistant member 13 is mounted on the thrust receiver 14. The lower end of the shaft 4 abuts on the thrust support 13.

A stator 9 is fixed to the outer surface of the bearing bush 3. The stator 9 is arranged to face the rotor magnet 7 of the rotor 6 with a gap 10 therebetween. In addition,
In the motor of the present embodiment, the length dimension of the rotor magnet 7 along the axial direction is longer than the length dimension of the stator 9, and the axial center point of the rotor magnet 7 is disposed above the axial center point of the stator 9. Is done.

With the above structure, when power is supplied to the stator 9 from the substrate 5 side, the shaft 4 and the rotor 6 are driven to rotate by the magnetic interaction between the stator 9 and the rotor magnet 7. On the other hand, the rotor magnet 7
Is equivalent to the center point of the length dimension of the rotor magnet 7, and since this center point is above the center point of the stator 9, a downward force acts on the shaft 4 and the shaft 4 The lower end is the thrust receiver 14 and the member 1
3 for thrust support.

Next, the function of the motor shown in FIG. As described above, the downward force acts on the shaft 4 due to the magnetic force, and the shaft 4 is prevented from coming off. However, this alone may not be sufficient. FIG. 2 shows a state where the shaft 4 is about to move upward by any external force. Shaft 4
The lower oil-impregnated metal bearing 2 is fitted to the lower part of the shaft, so that the lower oil-impregnated metal bearing 2 is also moved upward by the upward movement of the shaft 4, and the upper surface thereof is moved upward as shown in the figure. Hit the underside of However, since the upper oil-impregnated metal bearing 1 is fitted to the bearing bush 3, the lower oil-impregnated metal bearing 2 is restrained from moving upward at a position where it contacts the upper oil-impregnated metal bearing 1. for that reason,
The shaft 4 and the rotor 6 are prevented from coming off.

As described above, according to the present invention, unlike the prior art and the known art, a special member is not used to prevent the shaft from coming off, but only by devising the structure of the bearing for pivotally supporting the shaft 4, it is ensured. It is designed to keep from falling off. Therefore, it is not necessary to increase the axial length of the shaft 4, and the bending rigidity can be maintained. Of course, since separate parts are not used, the cost is reduced and the assemblability is improved. Further, since the whole is reduced in size and thickness, the weight can be reduced.

FIG. 3 shows an embodiment in which the present invention is applied to a motor having a slightly different structure from the motor shown in FIG. The upper oil-impregnated metal bearing 1a is fitted on the upper side of the bearing bush 3a which is erected and fixed on the substrate 5a, and the upper oil-impregnated metal bearing 1a is moved upward by the retaining portion 16 at the upper end of the bearing bush 3a. Is restrained from moving. On the other hand, the lower oil-impregnated metal bearing 2a is fitted to the shaft 4a, the lower end of which contacts the thrust receiver 14a on the substrate 5a. The bearing bush 3a is fixed by caulking its lower end flange portion with cut-and-raised pieces 5a 'of the substrate 5a (for example, at three locations in the circumferential direction of the bearing bush 3a).
The other structure is almost the same as that of the micromotor shown in FIG. 1, and the description thereof will not be repeated.

In the case of the motor shown in FIG. 3, the lower oil-impregnated metal bearing 2a is also prevented from coming off by contact with the upper oil-impregnated metal bearing. Further, the upper oil-impregnated metal bearing 1a
, The shaft 4a is more reliably prevented from falling off.

FIG. 4 shows still another motor employing the retaining structure of the present invention. A stepped portion 17 protruding in the radial direction is formed at an intermediate portion of the inner surface of the bearing bush 3b fixed to the substrate 5b. The stepped portion 17 is formed so as to project into the space 15 between the upper oil-impregnated metal bearing 1b and the lower oil-impregnated metal bearing 2b. The upper oil-impregnated metal bearing 1 is provided on the inner surface on the upper side of the bearing bush 3b.
b is fitted. A lower oil-impregnated metal bearing 2b is fitted to a lower side of the shaft 4b fitted to the rotor 6. Further, the shaft 4b is thrust supported by a thrust receiver 14b fitted to the lower end of the bearing bush 3b.

In the above structure, when the shaft 4b tries to come out upward, the upper surface of the lower oil-impregnated metal bearing 2b hits the stepped portion 17, and the further prevention is prevented. Also in the case of the present invention, the same effects can be obtained because special other components are not required for retaining the same as in the above embodiment.

[0020]

【The invention's effect】

1) According to the motor retaining structure of the first aspect of the present invention, the shaft and the rotor are securely retained without using special parts, and there is no need to increase the axial length of the shaft. Therefore, the size and thickness can be reduced, and the weight and cost can be reduced. Also, the assembling is easy and the workability can be improved. Further, the bending rigidity of the shaft is high, and stable rotation is performed. 2) According to the motor retaining structure described in claim 2 of the present invention, the retaining is more reliably performed by forming the stepped portion for retaining in the bearing bush. 3) According to the motor retaining structure described in claim 3 of the present invention, the shaft can be thrust supported by the thrust receiver on the lower end surface of the bearing bush.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a motor employing a retaining structure of the present invention.

FIG. 2 is a partially enlarged axial sectional view for explaining a retaining function in FIG. 1;

FIG. 3 is an axial sectional view of another motor employing the retaining structure of the present invention.

FIG. 4 is an axial sectional view of still another motor that employs the retaining structure of the present invention.

FIG. 5 is an axial sectional view of a conventional motor.

[Explanation of symbols]

 1, 1a, 1b Upper oil-impregnated metal bearing 2, 2a, 2b Lower oil-impregnated metal bearing 3, 3a, 3b Bearing bush 4, 4a, 4b Shaft 6 Rotor 7 Rotor magnet 9 Stator 10 Gap 14, 14a, 14b Thrust receiver 15 Space part 17 Stepped part

Claims (3)

[Claims] 1. A fixed vertical cylindrical bearing bush, a shaft pivotally supported by a pair of bearings inside the bearing bush, and a shaft provided on a portion of the shaft protruding above the bearing bush. A motor having a fixed rotor and a stator fixed to the rotor and fixed to the outside of the bearing bush and opposed to the rotor magnet via an appropriate gap, wherein the bearing is an upper oil-impregnated metal bearing and a lower oil-impregnated metal bearing The upper oil-impregnated metal bearing is fixed to the bearing bush and rotatably supports the shaft.
The retaining structure for a motor, wherein the lower oil-impregnated metal bearing is fixed to the shaft side to relatively rotate and support the bearing bush. 2. The motor according to claim 1, wherein a stepped portion projecting into a space between the upper oil-impregnated metal bearing and the lower oil-impregnated metal bearing is formed on an inner surface of the bearing bush. Retaining structure. 3. The motor retaining structure according to claim 1, wherein a thrust receiver is provided on a lower end surface of the bearing bush, and a lower end of the shaft is thrust supported by the thrust receiver.