JPH08116646A - Preloader for stepping motor - Google Patents

Abstract

PURPOSE: To obtain a preloader for stepping motor in which a side pressure is applied to a rotor without requiring any special component in order to stabilize the rotary shaft thus preventing noise. CONSTITUTION: The preloader for step motor comprises a rotary shaft 13 formed integrally with a rotor 10, a bearing 14 for supporting the rotary shaft 13, and a spring 16 interposed between the bearing 14 and the rotor 10 in order to apply a preload. The surface 15 of the rotor 10 for arranging the spring is inclined at a predetermined angle and a coil spring 16 is disposed around the rotary shaft 13 between the bearing 10 and the spring arranging surface 15. The coil spring 16 applies a side pressure to the rotor 10 through the inclining spring arranging surface 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preloading device for a stepping motor, and more particularly to a preloading device for a stepping motor which prevents abnormal noise caused by imbalance between a rotating shaft and a bearing portion.

[0002]

2. Description of the Related Art Generally, when a bearing is made of a sintered alloy, and when a metal rotary shaft is manufactured by polishing, the hole diameter of the bearing and the shaft diameter of the rotary shaft are 1 mm.
In the range of 10 mm to 10 mm, the processing accuracies are the same. That is, as shown in FIG. 7, whether the diameter of the rotating shaft 71 is 1 mm or more, the clearances A and B between the bearing hole 72 of the bearing and the rotating shaft 71 are the same.

Therefore, the bearing hole 72 of the bearing and the rotating shaft 7
The clearance setting value with 1 also does not change regardless of the shaft diameter. If the bearing has a small diameter, the clearance with respect to the diameter of the rotating shaft becomes large as shown in FIG. 6, and the play between the rotating shaft and the bearing hole becomes large. It is large, and the movement of the rotary shaft within the bearing hole, that is, the shaft misalignment, easily occurs with respect to the bearing hole during rotation.

Further, as shown in FIG. 5, in the relationship between the rotary shaft 54 of the stepping motor and the bearing 52, a spring 53 is arranged between the rotor 51 and the bearing 52 to preload in the axial direction (direction of arrow Y). There is a technology configured to work. However, the spring 53 does not generate lateral pressure (direction of arrow X). That is, the preload works in the axial direction of the rotor 51, but does not work in the radial direction of the rotor 51. Therefore, as shown in FIG. 6, the rotating shaft 54 does not move while making contact with the inner circumference of the bearing. For this reason, since the rotary shaft is neutral with respect to the bearing and freely moves, there is a disadvantage that the rotary shaft and the bearing collide with each other (so-called shaft misalignment), and abnormal noise is likely to occur.

As a means for preventing abnormal noise due to shaft misalignment, there is a technique for closing the clearance between the bearing and the rotary shaft at the manufacturing stage. In that case, a new device is introduced according to the diameter to make the clearance separate. Or it is necessary to take measures such as individually adjusting the bearing diameter and the rotating shaft diameter for each combination and individually selecting, which not only increases the number of manufacturing steps but also increases the cost.

Therefore, as a technique for solving the above problem without depending on the manufacturing apparatus as described above, various techniques for applying a lateral pressure to the rotating shaft to prevent the rotating shaft from being rough are proposed. For example, an electromagnet provided on a stator of a stepping motor, a magnetic body provided to face the electromagnet via an elastic member, and a braking attached to the magnetic body so as to face the rotor of the stepping motor. There is a technique in which a pad is provided, and the elastic body applies an urging force in a direction in which the elastic body is pressed against the rotor to the braking pad (see, for example, Japanese Utility Model Application Laid-Open No. 4-80282).

As another proposed technique, a rotor core is mounted on the outer periphery of one side of a motor shaft rotatably supported by a support frame, and the rotor core is housed in a stator.
A thrust-direction long hole is formed in the one end of the motor shaft, an elastic body is housed in the long hole, and a member that comes into point contact with a holding plate installed on a stator that houses the rotor core is the elastic body. There is also known a technique of interposing between the press plate and the holding plate (see, for example, Japanese Utility Model Laid-Open No. 2-7779).

[0008]

[Problems to be Solved by the Invention]
According to the technique proposed in Japanese Patent No. 80282, lateral pressure can be constantly applied by pressing the braking pad against the rotor, but sliding noise is generated due to sliding with the outer diameter of the rotor.
Moreover, the structure is complicated. See also Kaikai 2-7779
The technique proposed in Japanese Patent Publication has a disadvantage that the pre-load is applied by the sphere, but the assemblability is poor.

An object of the present invention is to provide a preloading device for a stepping motor in which lateral pressure is applied to the rotor without using special parts to stabilize the rotating shaft and prevent abnormal noise.

[0010]

A preload device for a stepping motor according to claim 1 of the present application is a rotary shaft formed integrally with a rotor, a bearing for supporting the rotary shaft, and a bearing arranged between the bearing and the rotor. A preload device for a stepping motor, comprising: a spring for applying a preload, and an outer circumference of a rotary shaft between the bearing and the spring placement surface, wherein the spring placement surface of the rotor is an inclined surface inclined at a predetermined angle. A coil spring is disposed on the rotor, and lateral pressure is applied from the spring to the rotor by the spring disposition surface that is the inclined surface.

A preload device for a stepping motor according to claim 2 of the present application provides a rotating shaft formed integrally with a rotor, a bearing for supporting the rotating shaft, and a preload arranged between the bearing and the rotor. In a stepping motor preload device including a spring, a coil spring is arranged on the outer circumference of the rotating shaft between the bearing and the spring arrangement surface, and between the rotor side end of the coil spring and the spring arrangement surface. It is characterized in that a piece is arranged on the rotor and a lateral pressure is applied from the spring to the rotor.

[0012]

According to the present invention, the spring arrangement surface of the rotor is an inclined surface inclined at a predetermined angle, and the coil spring is arranged on the outer periphery of the rotating shaft between the bearing and the spring arrangement surface to form the inclined surface. Since the lateral pressure is applied to the spring by the spring arrangement surface, the lateral pressure is constantly applied to the rotary shaft by the coil spring, so that the rotary shaft is constantly pressed against the inner diameter (inner peripheral surface) of the bearing to move. For this reason,
The rotation shaft is restricted in freedom within the bearing, collision between the rotation shaft and the bearing is prevented, and the rotation shaft rotates while slidingly contacting the inner peripheral surface of the bearing. It is possible to prevent the generated abnormal noise.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. The members, arrangements, and the like described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.

1 and 2 show an embodiment of the invention according to claim 1, FIG. 1 is an explanatory sectional view of a preload device for a stepping motor, and FIG. 2 is an operation explanatory view of FIG.
The stepping motor M in this example is composed of a stator (not shown) and a rotor 10.
Zero is arranged in the stator and is configured to rotate. The rotor 10 of this example includes a center piece 11 and
The magnet 12 and the rotor 12 are integrally formed with the rotary shaft 13 by press fitting and fixing.
The rotating shaft 13 is supported by bearings 14.
The bearings 14 and 12 of this example will be described by taking sliding bearings made of a sintered alloy as an example.

In this example, on one side of the center piece 11,
A spring placement surface 15 is formed of an inclined surface that is inclined in one direction by a predetermined angle. Then, the rotating shaft 13 between the bearing 14 and the spring disposition surface 15 composed of this inclined surface
A coil spring 16 is arranged on the outer periphery of the. The coil spring 16 of this example is fixed to the center piece 11. In this example, the coil spring 16 and the bearing 1
The washer 17 is disposed between the washer 17 and the No. 4.

According to the present embodiment, the coil spring 1 is formed by the spring disposition surface 15 of the center piece 11.
Not only in the coil up-and-down direction of 6, the elastic force having a certain directional property can be given, and the so-called coil spring 16 can apply the lateral pressure to the rotating shaft 13. That is, since the lateral pressure is constantly applied to the rotating shaft 13, the rotating shaft 13 is constantly pressed against the inner diameter of the bearing to move,
Collision between the rotating shaft 13 and the bearing 14 is prevented, and abnormal noise is prevented.

This operation will be described with reference to FIG. Figure 2
As shown by, when F is a force applied to the rotating shaft, f is a spring load, f _{H is a} spring load (horizontal direction), and f _{V is a} spring load (vertical direction), the spring placement surface 15
By inclining θ by θ °, the load f applied to the coil spring 16 is decomposed into two directions of f _{H and} f _V , and the lateral pressure f _H by the coil spring 16 always acts. Therefore, the lateral pressure F on one side always acts on the rotary shaft 13. As a result, the rotary shaft 13 cannot freely move as shown in FIG. 6, and as shown in FIG. 3, the rotary shaft 13 rotates while being in contact with the inner circumference of the bearing.

At this time, the lateral pressure f generated by the coil spring
_{Between H} and the lateral pressure F acting on the rotary shaft 13, F × l ₁ = f _H
There is a relationship of × l ₂ , f _H = l ₁ / l ₂ × F, and the angle θ is
_{f H = fsinθ, θ = sin} -1 determined by (f _H / f).

As a method of applying a lateral pressure by a spring, it is possible to preliminarily give the spring directivity unlike the above-described example. For example, the tip side of the spring is bent in one direction in advance, or both ends of the spring are bent, and the center of the spring is inclined in a certain direction. It is possible to position it on the plane of the surface and the plane of the bearing, but even in this way the spring does not have the expected shape, the stress is concentrated and the spring is dented, the spring is concentric As described above, it is difficult to make the pre-load, and when it is distorted, a predetermined lateral pressure is not generated, and the inconvenience occurs, so that the pre-load cannot be stably biased.

With the construction of this example, since the lateral pressure is constantly applied to the rotary shaft 13, the bearing is constantly pressed against the inner diameter of the bearing to move, so that the above-mentioned inconvenience does not occur and the preload (lateral pressure) is surely achieved. Can be configured to be generated.

FIG. 3 is an explanatory sectional view of a preloading device for a stepping motor according to a second aspect of the present invention. The same members and arrangements as those in the embodiment shown in FIGS. .

In this example, the piece 21 is replaced by the coil spring 16
And the spring disposing surface 15 are arranged so that the coil spring 16 generates a preload (lateral pressure) in a certain direction, as in the above embodiment. Therefore, in this example, unlike the above-described example, the center piece 11
There is no need to form an inclined surface on the. The other structure is the same as that of the above embodiment.

[0023]

In the shaft support structure in which the rotary shaft generally makes sliding contact with the inner peripheral surface of the bearing, particularly in the stepping motor having this structure, the larger the clearance between the bearing and the rotary shaft is, the more easily the rotary shaft is turbulent. Therefore, the noise becomes loud. Therefore, it is possible to suppress noise by configuring the rotary shaft so as to be preloaded as in the present invention. That is, since the lateral pressure always acts and the rotating shaft slides in a state of being urged and contacting the bearing, the noise is reduced and the noise becomes substantially constant regardless of the clearance. It is possible to reduce the size and ease the dimensional accuracy.

Further, in the case of a motor having a long operating time, the load on the sintered bearing can be reduced. That is, since the rotating shaft slides in a state of being urged and in contact with the bearing, there is no concentrated load or collision load on the shaft sliding surface due to the sway of the rotating shaft, and the bearing sliding surface due to the accumulated operation of the motor The generation of irregularities can be reduced, and as a result, the increase in noise over time can be suppressed.

As described above, the present invention is effective in the stepping motor preload device, particularly in the following cases. In other words, when there is a large clearance between the bearing and the rotating shaft, or when there is a large clearance due to initial part size variations, it is possible to prevent the rotating shaft from turbulence and to reduce the noise variation due to the product. Become.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view of a preload device for a stepping motor according to a first aspect of the present invention.

FIG. 2 is a diagram for explaining the operation of FIG.

FIG. 3 is an explanatory diagram showing a relationship between a bearing and a rotary shaft.

FIG. 4 is an explanatory sectional view of a preload device for a stepping motor according to a second aspect of the present invention.

FIG. 5 is an explanatory cross-sectional view of a preload device for a stepping motor showing a conventional example.

FIG. 6 is an explanatory diagram showing a relationship between a bearing and a rotary shaft.

FIG. 7 is an explanatory diagram of a clearance between a bearing and a rotating shaft.

[Explanation of symbols]

 10 Rotor 11 Centerpiece 12 Magnet 13 Rotating Shaft 14 Bearing 15 Spring Arrangement Surface 16 Coil Spring 17 Washer

Claims (2)

[Claims] 1. A preloading device for a stepping motor, comprising: a rotary shaft formed integrally with a rotor; a bearing for supporting the rotary shaft; and a spring arranged between the bearing and the rotor for providing a preload. In, the spring arrangement surface of the rotor is an inclined surface inclined at a predetermined angle, and a coil spring is arranged on the outer periphery of the rotating shaft between the bearing and the spring arrangement surface. A stepping motor preload device characterized in that a side pressure is applied from a spring to the rotor by means of a spring. 2. A preload device for a stepping motor, comprising: a rotary shaft integrally formed with a rotor; a bearing for supporting the rotary shaft; and a spring for providing a preload arranged between the bearing and the rotor. In, a coil spring is arranged on the outer circumference of the rotating shaft between the bearing and the spring arrangement surface,
A preload device for a stepping motor, characterized in that a piece is arranged between an end portion of the coil spring on the rotor side and a spring arrangement surface, and a side pressure is applied from the spring to the rotor.