JPH0695817B2 - Bearing structure of stepping motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor used for driving parts thereof, including the field of information equipment such as printers, facsimiles and copiers, and the field of industrial equipment such as sewing machines and FA equipment. , In particular, by configuring the bearing structure with a conductive resin having multiple protrusions, vibration is reduced, torque is increased by increasing the effective magnetic flux area, quality stability is improved compared to conventional bearing structures, and motor performance is improved. The present invention relates to a bearing structure for a stepping motor, which is intended to contribute to improving the performance of equipment by improving the performance.

[0002]

2. Description of the Related Art In recent years, the total demand for stepping motors has been increasing year by year, and their applications are widespread. Along with that, the competition of equipment performance has become fierce, and a minute improvement in motor performance has a large effect on the equipment performance difference. Against this background, demands for improved performance of motors are becoming stricter.

A conventional stepping motor bearing structure will be described below. FIG. 6 is a structural sectional view of a conventional stepping motor bearing structure. In FIG.
Reference numeral 1 is a rotor portion of the stepping motor. Reference numeral 2 is a stator portion configured with a rotor portion 1 and a constant gap,
The effective magnetic flux area is maintained at the width of B1. Since the torque of the motor is greatly affected by the width of B1, the width B1 is considered to be as large as possible. A winding portion 6 is formed in the stator. Reference numeral 3 is a conventional metal bearing boss, which is composed of a pair of upper and lower bearings 5 and a bearing 5 inserted in advance.

Since both the surface of the bearing boss and the surface of the stator are made of metal, they are fixed by welding at the joint portion 9. Welding and fixing are performed at multiple points and the welding state is checked. Further, an upper cover 7 and a lower cover 8 are attached to form a stepping motor.

[0005]

However, in the above-mentioned conventional structure, since it is necessary to join the bearing boss and the surface of the stator, the thickness of the bearing boss is inserted into the stator, so that the bearing boss and the rotor are inserted. If a certain gap A1 or A2 is to be taken, it is necessary to reduce the width of B1, which leads to a decrease in the effective magnetic flux area, and the torque of the motor tends to decrease. Further, if the flatness of the above-mentioned joint is not stabilized, welding fixation is affected, and therefore precise management is required. Further, when the metal-to-metal joint is unstable, a high-frequency vibration sound is generated, and the vibration of the rotor generated by continuous step driving tends to be amplified. It is considered that this tendency is also due to the fact that the metal bearing bosses are fixed by welding in place. It is also conceivable that the upper cover is made of metal and has a thin structure, and that there are few fixed contact portions and that no object that absorbs vibration is interposed.

The present invention solves the above-mentioned conventional problems by increasing the effective magnetic flux area obtained when the stator and the rotor face each other to increase the torque of the motor.
The bearing boss is made of a resin material that has a great effect of vibration damping,
A conductive resin material is used to dissipate the static electricity that charges the rotor when the motor is mounted.The structure also has a high degree of cushioning, and the joint stability between the bearing boss and the stator is increased to improve the motor stability. It is an object of the present invention to provide a stepping motor bearing structure capable of improving torque performance and vibration performance.

[0007]

In order to achieve this object, a bearing structure of a stepping motor according to the present invention uses a conductive resin material as a bearing boss material, and further comprises a plurality of protrusions on the surface thereof. It has a structure in which the used stator and cover are fixed by flexible insertion.

[0008]

With this structure, welding fixing by bearing the bearing boss and the surface of the stator together is unnecessary. Therefore, it is not necessary to insert the thickness of the bearing boss into the stator, and the thickness of the bearing boss can be increased to increase the effective magnetic flux area where the rotor and the stator face each other, which leads to an increase in torque. In addition, since the bearing boss made of conductive resin can have a complicated shape due to its material performance, multiple protrusions are formed on the surface of the bearing boss, and the flexibility of the protrusions fixes the stator and upper and lower covers by sandwiching them. Made possible Along with this, a vibration damping effect on the upper cover can be enabled.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1, FIG. 2, and FIG. 3, 10 is a bearing boss made of a conductive resin, and 11 is a bearing boss 1.
It is a portion that is flexibly fixed by a plurality of spherical projections 12 provided on the surface of 0.

In the bearing boss having the above structure,
The combination of the bearing boss and the stator is performed with the dimension E in FIG. E dimension is 1/3 compared to the conventional metal bearing boss
It is the following numerical value, and the remaining 2/3 or more is C of FIG.
1, C2. Therefore, the width D1 of the effective magnetic flux area of the rotor facing the stator can be set to D1> B1 as compared with the conventional width B1. That is, it becomes possible to increase the torque.

In fixing the bearing boss of this embodiment, a plurality of spherical projections provided on the surface of the bearing boss are pressed by the upper and lower covers,
It is held by sandwiching it with the stator. At this time, it is necessary to flexibly adjust the cumulative tolerance between the upper and lower covers by the spherical projections, and in this embodiment, this flexibility is realized by welding and adjusting the spherical projections. With this configuration, the vibration of the rotor is distributed to the stator and the cover, and the vibration of the motor can be reduced. In addition, the strength of the upper cover is also reinforced, and the bearing boss of the present invention including the material characteristics of the conductive resin has the effect of a vibration damping material.

FIG. 4 shows the torque characteristic of the conventional stepping motor bearing boss using the bearing boss of the stepping motor according to this embodiment, and FIG. 5 shows the vibration characteristic thereof.

As is apparent from FIG. 1, the bearing boss structure according to this embodiment can increase the torque by about 15% when the torque is up to 2000 PPS. Further, as is apparent from FIG. 5, the bearing boss structure according to the present embodiment greatly improves the vibration having the low frequency component around 1 kHz.

As described above, according to the present embodiment, the conventional metal bearing boss is welded and fixed, and is formed of a conductive resin having a plurality of protrusions, and the bearing boss has a sandwiched structure between the stator and the motor cover. By doing so, the effective magnetic flux area of the rotor can be increased, and the torque can be increased by about 15%. Further, the sandwiching structure causes a buffering effect of the motor vibration to reduce the vibration, which can greatly contribute to the performance improvement of various devices used.
When mounted on a motor, for example, when used in an electronic typewriter, etc., static electricity is generated due to the rotation of the plastic type letters, which charges the rotor and cannot escape to the ground. Discharge at
The microcomputer used in the equipment may malfunction. In order to prevent this phenomenon, a conductive resin is used for the bearing boss so that static electricity can escape to the ground.

[0016]

As described above, according to the present invention, by providing a plurality of protrusions for a flexible pinching structure and providing a bearing boss that mechanically and electrically contacts a motor cover, vibration and torque can be reduced. It is possible to realize an excellent bearing structure of a stepping motor that can improve the characteristics and the performance of the device.

[Brief description of drawings]

FIG. 1 is a motor sectional view of a bearing structure of a stepping motor according to an embodiment of the present invention.

FIG. 2 is an external view of a bearing boss of a stepping motor according to an embodiment of the present invention.

FIG. 3 is an enlarged view of an essential part for explaining flexible pinching in the bearing structure of the stepping motor in the embodiment of the invention.

FIG. 4 is a torque characteristic comparison diagram of a stepping motor according to an embodiment of the present invention and a conventional stepping motor.

5A is a vibration characteristic diagram of a conventional stepping motor, and FIG. 5B is a vibration characteristic diagram of a stepping motor according to an embodiment of the present invention.

FIG. 6 is a motor cross-sectional view of a conventional stepping motor bearing structure.

[Explanation of symbols]

 2 stator 7 motor cover 10 conductive resin bearing boss 12 spherical projection

Claims (2)

[Claims] 1. In a stepping motor comprising a stator, a rotor, a bearing for rotatably supporting the rotor, and a bearing boss for holding the bearing, a resin-molded bearing boss is sandwiched between the stator and the cover. ,
A bearing structure for a stepping motor, wherein the bearing boss is provided with a projection that makes point contact with the cover. 2. A bearing structure for a stepping motor according to claim 1, wherein the bearing boss is molded of a conductive resin to provide conductivity between the cover, the stator and the rotor.