JPH06217479A - Rotor for motor - Google Patents

Abstract

PURPOSE:To provide a rotor for motor in which vibration and noise can be suppressed as low as possible. CONSTITUTION:A rotor body 2 is injection molded concentrically about a shaft 1 using a liquid crystal polymer. A recess 5a is made in the outer peripheral face of an outer cylindrical section 5 constituting a rotor body and first and second cylindrical permanent magnets 6, 7 and a cylindrical spacer 8 are fitted in the recess 5a. Liquid crystal polymer has good vibration damping characteristics and vibration is retarded in a motor or various OA machines mounting such rotor(vibration is damped in a relatively short time) and noise is also suppressed. Furthermore, since high dimensional accuracy can be achieved, dimensional unbalance causing acceleration of noise and also magnetic unbalance can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor used for a permanent magnet type stepping motor or the like.

[0002]

2. Description of the Related Art In the case of a permanent magnet type stepping motor, for example, as shown in FIG. 4, a permanent magnet is formed around a cylindrical rotor body b in which a shaft a is inserted and arranged in a central portion, with an adhesive layer c interposed therebetween. d is bonded and integrated. The shaft a is rotatably supported by a motor main body (not shown), and the inner peripheral surface of the motor main body (rotor main body b
A stator yoke provided with magnetic pole teeth is arranged at a position facing (permanent magnet d)). Then, the rotor body b is formed using a metal such as an iron plate or aluminum, or recently, is formed using a synthetic resin such as PBT.

[0003]

By the way, the above stepping motor is mounted in an OA device such as a hard disk (floppy disk) drive device. However, noises and vibrations that occur during rotation in recent years have become a problem, and such noises, etc. There has been a demand to reduce as much as possible.

However, in the above-mentioned conventional rotor, the vibration damping characteristic is poor and vibration is likely to occur, making it difficult to reduce noise. Further, when it is made of metal, the inertia becomes large, which causes a problem of promoting the vibration. Further, in the case of PBT, the above-mentioned problem due to inertia is not so large, but since the molding shrinkage rate is large, imbalance in size and shape occurs, and accordingly magnetic imbalance also occurs. As a result, the rotor does not rotate smoothly, causing uneven rotation, which also causes vibration, and the vibration damping characteristic is not good.

The present invention has been made in view of the above background, and an object of the present invention is to provide a rotor for a motor capable of suppressing the occurrence of vibration and the accompanying noise as much as possible. is there.

[0006]

In order to achieve the above-mentioned object, in the present invention, a substantially cylindrical rotor body is arranged on the outer periphery of a shaft portion rotatably supported by the motor body, and the rotor body is also provided. A rotor for a motor, in which a permanent magnet is mounted at a predetermined position on the outer surface of, and at least the rotor body is formed of a liquid crystal polymer.

[0007]

[Function] Since liquid crystal polymer has good vibration damping characteristics, it can be stopped when step driven (especially when stopped (including temporary stop).
When the rotor tries to vibrate due to inertial force,
Since the rotor body made of liquid crystal polymer is located around the shaft where vibration is most likely to occur, it is difficult for the vibration to occur, and the vibration is attenuated in a relatively short time after the occurrence of the vibration. As a result, noise generation due to vibration is also suppressed.

Further, since the liquid crystal polymer can exhibit high dimensional accuracy after molding, the imbalance in size and shape, and hence the magnetic imbalance is reduced, and further, the liquidity is good and the strength is strong, so that it is thin and compact. Can be
Thereby, the inertia is reduced. This makes it more difficult for vibration to occur.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a motor rotor according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an embodiment of a rotor according to the present invention. As shown in the drawing, a rotor body 2 is concentrically provided around the outer periphery of a shaft 1. The rotor body 2 is molded by injection molding using a liquid crystal polymer. The inner cylindrical portion 3 has an inner diameter that matches the outer diameter of the shaft 1.
And a disc-shaped connecting member 4 formed in a protruding state outside the axial center position of the inner cylindrical portion 3, and connected to the outer peripheral side edge of the connecting member 4 so as to be concentric with the inner cylindrical portion 3. It is formed from the outer cylindrical portion 5 arranged.

A concave portion 5a extending in the circumferential direction is formed on the outer peripheral surface of the outer cylindrical portion 5, and the cylindrical first and second permanent magnets 6, 7 and the cylindrical shape are formed in the concave portion 5a. The spacer 8 is attached. In this example, the thicknesses of the first and second permanent magnets 6, 7 and the spacer 8 are substantially the same, and the recess 5
The depth of a is shallower than the wall thickness. As a result, as shown in the drawing, the end portions of both permanent magnets 6 and 7 are exposed. It should be noted that this is because the permanent magnets 6 and 7 and the spacer 8 are inserted and arranged in a mold for injection molding, and both ends of the permanent magnets 6 and 7 are gripped to position the respective parts. It is the above request. The spacer 8 may be formed of a metal such as aluminum or a synthetic resin, and may be formed of a liquid crystal polymer (preliminarily formed) like the rotor main body 2. Is optional, but when formed of a liquid crystal polymer, the generation of vibration and noise can be further reduced.

The liquid crystal polymer forming the rotor body 2 has good vibration damping characteristics, and the rotor body made of such liquid crystal polymer is located around the shaft where vibration is most likely to occur when step-driving. In addition, vibration is unlikely to occur in a motor equipped with the rotor of the present invention, and thus various OA devices, etc. (vibration is attenuated in a relatively short time after occurrence of vibration), and noise generation due to vibration can also be suppressed.
In addition, since the liquid crystal polymer can have high dimensional accuracy after molding, the imbalance in size, which promotes the generation of noise, and eventually the magnetic imbalance is reduced. In addition, it has good fluidity and strong strength
The size can be reduced, and the inertia can be reduced accordingly. That is, it is possible to eliminate the conventional causes of vibration and noise.

Next, noise was measured in order to verify the effect of the above-mentioned embodiment. That is, as shown in FIG. 2, the motor 10 to be measured (manufactured by using each rotor body formed by using the liquid crystal polymer (LCP) of this example, conventional aluminum and PBT (comparative example)) Is hung by a thread 11, and the motor 10 is rotationally driven with the driving frequency appropriately changed in that state, and the noise generated at that time is collected by a microphone 12 arranged at a position 50 mm away from the motor 10. Was measured by a sound level meter 13 connected to the microphone 12. And the result is shown in FIG. As shown in the figure, the noise generated from the rotor (motor) manufactured using the liquid crystal polymer of the present invention was minimized.

In the above embodiment, the rotor body 2
When installing permanent magnets etc. on the outer periphery of the rotor, injection molding was used to mount the rotor magnets at the same time as manufacturing the rotor body. May be fixed by adhesion or the like, and further, the shaft or the like may of course be manufactured using a liquid crystal polymer. Furthermore, in the above-described embodiment, a rotor used for a two-phase stepping motor and a type using two axially separated permanent magnets in order to reduce the amount of permanent magnets used has been described. However, for example, one permanent magnet that is long in the axial direction may be used, and a single-phase or multi-phase motor may be used and various types of motors may be used. In short, at least the rotor body is made of a liquid crystal polymer. It should be done.

[0014]

As described above, since the motor rotor according to the present invention is formed of the liquid crystal polymer, it is possible to suppress the occurrence of vibration as much as possible and reduce the noise generated by such vibration. Further, since the liquid crystal polymer has high strength and good fluidity, it can be made thin, and secondary effects such as weight reduction and size reduction are also generated.

[Brief description of drawings]

FIG. 1 is a sectional view showing a preferred embodiment of a motor rotor according to the present invention.

FIG. 2 is a diagram illustrating a configuration of an apparatus used for a noise experiment.

FIG. 3 is a diagram showing experimental results for demonstrating the effect of the present invention.

FIG. 4 is a sectional view showing an example of a conventional motor rotor.

[Explanation of symbols]

 1 shaft 2 rotor body 6,7 first and second permanent magnets

Claims (3)

[Claims] 1. A rotor for a motor, wherein a substantially cylindrical rotor body is arranged on the outer periphery of a shaft portion rotatably supported by the motor body, and a permanent magnet is mounted at a predetermined position on the outer surface of the rotor body. A rotor for a motor, wherein at least the rotor body is made of a liquid crystal polymer. 2. A rotor for a motor, wherein the permanent magnet is divided into a plurality of parts in the axial direction, and a spacer member is interposed between adjacent permanent magnets, wherein the spacer member is formed of a liquid crystal polymer. The rotor for a motor according to claim 1, wherein: 3. The motor rotor according to claim 1, wherein the shaft portion and the rotor body are integrally formed of liquid crystal polymer.