JP3065492B2 - Stepping motor preload device - Google Patents

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 formed from a sintered alloy or when a metal rotary shaft is manufactured by polishing, the diameter of the bearing hole and the diameter of the rotary shaft are 1 mm.
In the range of 10 mm to 10 mm, each processing accuracy is substantially the same. That is, as shown in FIG. 7, the clearances A and B between the bearing hole 72 of the bearing and the rotating shaft 71 are the same regardless of whether the diameter of the rotating shaft 71 is 1 mm or more.

For this reason, the bearing hole 72 of the bearing and the rotating shaft 7
The clearance setting value of 1 does not change irrespective 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. It is large, and the rotation shaft easily moves in the bearing hole with respect to the bearing hole during rotation, that is, the shaft is apt to be warped.

As shown in FIG. 5, a spring 53 is provided between the rotor 51 and the bearing 52 in the relationship between the rotating shaft 54 of the stepping motor and the bearing 52, and a preload is applied in the axial direction (Y direction of the arrow). There are technologies that are configured to work. However, the spring 53 does not generate a lateral pressure (the direction of the arrow X). That is, the preload acts in the axial direction of the rotor 51, but does not act in the radial direction of the rotor 51, so that the rotating shaft 54 does not move while contacting the inner circumference of the bearing as shown in FIG. Therefore, since the rotating shaft is neutral with respect to the bearing and moves freely, there is a disadvantage that the rotating shaft and the bearing collide with each other (so-called unevenness of the shaft) to easily generate abnormal noise.

[0005] As a means for preventing abnormal noise due to shaft unsteadiness, there is a technique for reducing the clearance between the bearing and the rotating shaft at the manufacturing stage. In this case, a new device is introduced according to the diameter and the clearance is individually adjusted. It is necessary to take measures such as adjusting the diameter of the bearing and the diameter of the rotating shaft individually for each combination, and selecting each of them individually. This not only increases the number of manufacturing steps but also increases the cost.

Therefore, as a technique for solving the above-mentioned problem without depending on the manufacturing apparatus as described above, various techniques have been proposed in which lateral pressure is applied to the rotating shaft to prevent the rotating shaft from running out. 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 brake attached to the magnetic body in a state facing 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 of pressing against the rotor to the brake pad (for example, see Japanese Utility Model Laid-Open No. 4-80282).

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

[0008]

SUMMARY OF THE INVENTION
In the technique proposed in Japanese Patent Publication No. 80282, a lateral pressure can always be applied by pressing a braking pad against a rotor, but a sliding noise is generated due to sliding with the rotor outer diameter.
Further, the structure is complicated. 2-7779
In the technique proposed in Japanese Patent Application Laid-Open Publication No. H11-157, the preload is applied by a sphere, but there is a disadvantage that the assemblability is poor.

An object of the present invention is to provide a stepping motor preloading device which applies a lateral pressure to a rotor without using any special parts, stabilizes a rotating shaft, and prevents abnormal noise.

[0010]

According to a first aspect of the present invention, there is provided a stage according to the first aspect.
The preloading device of the motor includes a rotating shaft formed integrally with the rotor, a sintered alloy sliding bearing that supports the rotating shaft,
In pressure unit of the stepping motor and a spring providing a preload which is disposed between the sintered alloy sliding bearing and the rotor, and inclined surface is inclined spring arrangement surface of the rotor at a predetermined angle, wherein the sintering A spring is arranged on the outer periphery of the rotating shaft between the coupling gold sliding bearing and the spring mounting surface, and the rotating shaft is radially preloaded in response to the rotation of the rotor from the spring by the inclined spring mounting surface.
It is characterized in that the applied lateral pressure is urged against the rotor.

[0011] pressure unit of the stepping motor according to the claims 2, between the rotating shaft formed on the rotor and integrally sintered alloy sliding bearing for supporting the rotary shaft, and said sintered alloy sliding bearing and the rotor And a spring for applying a preload disposed on the stepping motor.
A spring is arranged on the outer periphery of the rotating shaft between the sintered alloy plain bearing and the spring arrangement surface, and a bridge is arranged between the rotor side end of the spring and the spring arrangement surface to rotate the rotor from the spring. Rotary shaft is preloaded radially according to
The lateral pressure which is characterized by being urged in the rotor.

[0012]

According to the present invention, the spring arrangement surface of the rotor is inclined at a predetermined angle, and a spring is disposed on the outer periphery of the rotating shaft between the sintered alloy sliding bearing and the spring arrangement surface. Since the side pressure is applied to the spring by the spring arrangement surface, the side pressure is applied to the rotating shaft by the spring so that the rotating shaft is radially pre-pressed. Therefore, the rotating shaft is always applied to the bearing inner diameter (inner peripheral surface). Exercise by being pressed. Therefore, the rotation axis becomes to be regulated freely within sintered alloy sliding bearing, is prevented collision of the rotary shaft and the sintered alloy sliding shaft <br/> receiving is, the rotation axis of the sintered alloy sliding bearing Since the rotation is performed while the peripheral surface is in sliding contact, abnormal noise generated between the sintered alloy sliding bearing and the rotating shaft can be prevented.

[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 present invention.

[0014] Figures 1 and 2 show an embodiment of the invention according to claim 1, 1 is an explanatory cross-sectional view of a pressure unit of the stepping motor, Fig. 2 is an explanatory diagram of the operation of FIG.
The stepping motor M in the present example includes a stator (not shown) and a rotor 10.
0 is arranged in the stator and configured to rotate. The rotor 10 of the present example includes a center piece 11,
The rotor is integrally formed with the rotating shaft 13 by press-fitting and the like.
The rotating shaft 13 is supported by a bearing 14.
The bearings 14 and 12 of the present embodiment will be described by taking a plain bearing made of a sintered alloy as an example.

In this embodiment, on one side of the center piece 11,
A spring arrangement surface 15 is formed as an inclined surface inclined at a predetermined angle in one direction. The rotating shaft 13 between the spring arrangement surface 15 formed of the inclined surface and the bearing 14
A coil spring 16 as a spring is disposed on the outer periphery of the coil. The coil spring 16 of this example is fixed to the center piece 11. In this example, a washer 17 is arranged between the coil spring 16 and the bearing 14.

In the case of this embodiment, the coil spring 1 is formed by the spring arrangement surface 15 of the center piece 11.
6, a resilient force having a certain directionality can be given in addition to the vertical direction of the coil, and a so-called coil spring 16 can urge a side pressure against the rotating shaft 13. That is, since the side pressure is always applied to the rotating shaft 13, the rotating shaft 13 is always pressed against the bearing inner diameter and moves.
Collision between the rotating shaft 13 and the bearing 14 is prevented, and generation of abnormal noise is prevented.

[0017] will be described with reference to this effect in Figure 2. FIG.
As shown in, F: force applied to the rotary shaft, f: spring load, _{f H:} spring load (horizontal direction), _{f V:} When spring load (vertical direction), the spring arrangement surface 1
By tilting 5 θ °, or the coil spring 16
Cal load f is, _{f H,} is decomposed into two directions _{f V,} so that the lateral pressure _{f H} by the coil spring 16 acts constantly.
Therefore, the side pressure F always acts on the rotating shaft 13 to one side. That is, due to the lateral pressure F, the rotating shaft 13 is moved in the radial direction.
And the rotating shaft 13 comes into contact with the inner periphery of the bearing. As a result, as shown in FIG. 6, the rotating shaft 13 cannot move freely, and as shown in FIG. 3, the rotating shaft 13 rotates while being in contact with the inner periphery of the bearing.

At this time, the lateral pressure f due to the coil spring
_H × the lateral pressure F acting on the rotating shaft 13, F × l ₁ = f
_H × l ₂ , fH = l ₁ / l ₂ × F, and the angle θ
Is determined by f _H = f sin θ, θ = sin ⁻¹ (f _H / f).

As a method of applying the side pressure by the spring, it is conceivable to give the spring a direction in advance, unlike the above-described example. For example, the tip side of the spring is formed by bending in one direction in advance, or both ends of the spring are bent, and furthermore, the center of the spring is formed to be inclined in a certain direction. It is conceivable that the spring is undulated and does not have the expected shape, or the stress is concentrated due to stress concentration, and the spring is concentric. If the preload is difficult to produce, or if the preload is distorted, a predetermined lateral pressure will not be generated, and the preload cannot be urged stably.

With the configuration as in the present embodiment, since the lateral pressure is always applied to the rotating shaft 13, the rotary shaft 13 is always pressed against the inner diameter of the bearing and moves. Can be generated.

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

In this embodiment, the piece 21 is connected to the coil spring 16
The coil spring 16 is arranged between the coil spring 16 and the spring arrangement surface 15 so that the coil spring 16 generates a preload (side pressure) in a certain direction, similarly to the above embodiment. For this reason, in this embodiment, unlike the above embodiment, the center piece 11
It is not necessary to form an inclined surface on the surface. Other configurations are the same as those of the above embodiment.

[0023]

In general, in a shaft supporting structure in which the rotating shaft slides on the inner peripheral surface of the bearing, a step having this structure is particularly preferred.
In a ping motor , the greater the clearance between the sintered alloy plain bearing and the rotating shaft, the more easily the rotating shaft becomes unsteady, and thus the greater the noise. Therefore, noise can be suppressed by configuring the rotating shaft to be preloaded as in the present invention. In other words, since the lateral pressure is always applied and the rotating shaft is urged to the sintered alloy sliding bearing and slides in contact therewith, the noise is reduced and the noise becomes almost constant regardless of the clearance, so that the initial product It is also possible to reduce variations in noise and ease dimensional accuracy.

[0024] Further, when the operation time is long motor, sintered
The load on the alloy sliding bearing can be reduced. That is, since the rotating shaft slides in a state of being urged and contacted with the sintered alloy sliding bearing , there is no concentrated load or collision load on the shaft sliding surface due to the running of the rotating shaft, and the bearing due to the cumulative operation of the motor. The occurrence of unevenness on the sliding surface can be reduced, and as a result, the increase in noise over time can be suppressed.

[0025] According to the present invention, as described above, Steppin '
This is effective in the preloading device for the motor , particularly in the following cases. In other words, when the clearance between the sintered alloy plain bearing and the rotating shaft is large, or when there is a large clearance due to variations in the initial part dimensions, it is possible to prevent the rotating shaft from running out, and to reduce noise caused by the product. Variation is small.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a preloading device for a stepping motor according to claim 1;

FIG. 2 is an operation explanatory view of FIG. 1;

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

FIG. 4 is an explanatory sectional view of a preloading device for a stepping motor according to claim 2;

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

FIG. 6 is an explanatory diagram showing a relationship between a bearing and a rotating 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 Rotation axis14 Bearings (sintered alloy plain bearings)  15 Spring arrangement surface 16 Coil spring 17 Washer

Claims (2)

(57) [Claims] 1. A rotor and a rotary shaft formed integrally disposed a preload between the sintered alloy sliding bearing for supporting the rotary shaft, and said sintered alloy sliding shaft <br/> receiving the rotor A stepping motor preload device comprising:
The spring arrangement surface of the rotor is an inclined surface inclined at a predetermined angle, and a spring is arranged on the outer periphery of a rotating shaft between the sintered alloy sliding bearing and the spring arrangement surface, and the spring arrangement is the inclined surface. pressure unit of the stepping motor, characterized in that the lateral pressure rotating shaft is preloaded in the radial direction in accordance with rotation of the spring of the rotor formed by biasing the rotor by a surface. 2. A rotor and a rotary shaft formed integrally disposed a preload between the sintered alloy sliding bearing for supporting the rotary shaft, and said sintered alloy sliding shaft <br/> receiving the rotor A stepping motor preload device comprising:
A spring is arranged on the outer periphery of the rotating shaft between the sintered alloy plain bearing and the spring arrangement surface, and a bridge is arranged between the rotor side end of the spring and the spring arrangement surface to rotate the rotor from the spring. Rotary shaft is preloaded radially according to
A preloading device for a stepping motor, wherein a side pressure applied to the rotor is applied to the rotor.