JPH0662559A - Pm type stepping motor - Google Patents

Abstract

PURPOSE:To provide a PM type stepping motor that causes low vibration and noise. CONSTITUTION:A spacer 11 is sandwiched between first and second magnets 5a fixed to a shaft 6. The inside diameter of this spacer 11 is set larger than the outside diameter of the shaft 6, and a rotor made of an elastic body 12 is sandwiched between the inside diameter surface of the spacer 11 and the outside diameter surface of the shaft 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PM type stepping motor used in a head drive device of a floppy disk drive, a lens drive device of a video camera, a drive device of various OA equipment and the like.

[0002]

2. Description of the Related Art In recent years, miniaturization, thinning, and high-classification of equipment have been rapidly progressing, and PM type stepping motors used in such equipment have also been made compact, thin, low in vibration, and low in noise. There is a demand for conversion.

A PM type stepping motor used in a conventional floppy disk drive will be described below. 2 is a sectional view of a conventional PM type stepping motor, and FIG. 3 is a perspective view of a yoke. In FIG. 2 and FIG. 3, reference numeral 1 is a conducting wire, which is wound around the first coil bobbin 2. Reference numeral 3 denotes a yoke having a plurality of comb-teeth-shaped pole teeth 3a on its inner circumference (see FIG. 3), which are arranged on both sides of the coil bobbin 2 to form a first stator portion. This first stator part is provided with a second stator part similar to the first stator part.
The stator portions are overlapped with each other, and the first and second stator portions constitute the stator portion. The stator portion is housed in a cup-shaped motor frame 4 with its outer periphery abutting.
A plurality of magnetized magnets 5 are fixed to the shaft 6 on the outer peripheral surface facing the plurality of pole teeth 3a to form a rotor. This rotor is rotatably held by a bearing 7 fixed to the motor frame 4, a pivot bearing 9 provided in the mounting bracket 8, and a holding spring 10 provided in the opening of the motor frame 4.

In the above structure, the conductor wire 1 of each stator section
The comb-shaped pole teeth 3a of the yoke 3 by sequentially energizing the
Are excited, and the rotor is rotated by the attraction or repulsion of the magnets 5 which are magnetized opposite to the magnets.

[0005]

However, in the above-mentioned conventional configuration, the distance between the outer peripheral surface of the magnet 5 and the plurality of pole teeth 3a of the yoke 3 facing the outer peripheral surface is not uniform, or the outer circumference of the magnet 5 is not uniform. When the surface magnetic flux density of a plurality of magnetized portions of the surface becomes non-uniform, the attraction or repulsion force between the magnet 5 and the plurality of pole teeth 3a of the yoke during rotor rotation becomes non-uniform. There is a problem that the rotor vibrates greatly due to the noise and the noise when driving the motor becomes high.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a PM type stepping motor having low vibration and low noise.

[0007]

In order to achieve this object, a PM type stepping motor of the present invention has a spacer provided on a rotor shaft and between two magnets, the spacer being supported by an elastic body. I am trying.

[0008]

In this structure, the vibration of the rotor during rotation of the rotor is damped by the spacer and the elastic body, and the vibration of the motor
It will reduce noise.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same components as those in the conventional example are designated by the same reference numerals.

As shown in FIG. 1, a plurality of magnetized two magnets 5a are fixed to the shaft 6 by press-fitting and gluing on the outer periphery of the shaft 6, which is arranged so as to face the plurality of pole teeth 3a of each yoke. The brass spacer 11 is supported between the two magnets 5a on the shaft 6 only by the elastic body (rubber) 12 without contacting the two magnets 5a. The inner diameter of this brass spacer 11 is
The elastic body (rubber) 12 is arranged in the circumferential direction of the shaft 6 so that the outer diameter of the spacer 11 does not exceed the outer diameter of the magnet 5a by setting the outer diameter of the shaft 6 to the middle of the outer diameter of the spacer 11. They are evenly arranged. Since the structure of the stator and the structure for holding the rotor are the same as those of the conventional example, description thereof will be omitted.

The operation of the PM type stepping motor of the present embodiment constructed as described above will be described below.
First, by energizing the conductor 1, the rotor operates in the same manner as in the conventional example, and the rotor rotates. At this time, the rotor vibrates due to magnetic nonuniformity which is generated by precision. When the rotor starts to vibrate, the inertial force of the brass spacer 11 supported by the elastic body (rubber) 12 acts to suppress the vibration of the rotor.

As described above, according to this embodiment, since the spacer 11 supported by the elastic body (rubber) 12 is provided on the shaft 6 of the rotor, the vibration when the PM type stepping motor is driven is reduced. It can suppress and reduce noise.

In this embodiment, the inner diameter of the spacer 11 is
Although the intermediate diameter of the outer diameter of the shaft 6 and the outer diameter of the spacer 11 is set approximately, the inner diameter of the spacer 11 may be changed depending on the characteristics of the PM type stepping motor embodying the present invention, the length of the magnet 5a, and the like. Further, although the material of the spacer 11 is brass, it goes without saying that other materials such as other metals and synthetic resins may be used. Further, although the elastic body 12 is made of rubber, it goes without saying that the elastic body 12 may be made of other elastic material such as synthetic resin.

[0014]

As is apparent from the above description of the embodiments, the present invention has a structure in which the rotor is provided with the spacer supported by the elastic body, so that an excellent PM type stepping motor with small vibration and low noise can be obtained. Can be realized.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a conventional PM type stepping motor.

FIG. 3 is a perspective view of a yoke of a PM type stepping motor.

[Explanation of symbols]

 2 coil bobbin 3 yoke 3a yoke pole tooth 5, 5a magnet 11 spacer 12 elastic body

Claims (1)

[Claims] 1. A shaft, a first magnet fixed to the shaft, a second magnet fixed to the shaft at a distance from the first magnet, and the first and second magnets. PM type stepping motor including a spacer provided between the spacers and having an inner diameter larger than the outer diameter of the shaft, and a rotor including an elastic body arranged between the inner diameter surface of the spacer and the outer diameter surface of the shaft. .