JPS6051451A - Linear stepping motor - Google Patents

Abstract

PURPOSE:To suppress the variation in the moving distance of every one step to extremely small value when a motor is stepwisely driven by disposing a soft magnetic material at the advancing direction side of a moving element to a stator core secured to a base. CONSTITUTION:A plurality of metal plates 14 of a soft magnetic material are bonded fixedly, and bonded fixedly to the surface of a base at both sides of the advancing direction of a moving element 2 to stator cores 3, 4 secured into a containing hole 11 of a base 1 of a linear stepping motor. A magnetic flux from a portion not opposed to the teeth 3a, 3b, 4a, 4b of the stator core of slider pieces 7, 8 secured to the element 2 is passed through the plates 14. Thus, only magnetic fluxes from the pieces 7, 8 opposed to the teeth 3a, 3b, 4a, 4b are passed, and the cores 3, 4 are held substantially in constant magnetic flux density. Accordingly, no unbalance in the thrusts occurs among the teeth 3a, 3b, 4a, 4b, and the variation in the moved distance per one step can be largely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a linear stepping motor.

Linear stepping motors are currently being widely used as drive sources for driving magnetic heads in magnetic disk drives.
As one example, the present applicant has already filed a Utility Application filed in 1983-125.
695 has a structure as shown in "2". As shown in FIG. 1, this linear stepping motor is roughly composed of a base 1 that is the fixed side of the motor and a mover 2 that is the movable side of the motor. A stator storage hole 11 is provided for storing and fixing the coil 5.6 wound around the stator core. In this storage hole 11, the stator core 3,
4 is fixed with its teeth 3a, 3b, 4a, 4b slightly protruding from the upper surface of the base 1.

On the other hand, the mover 2, which is the movable side of the motor, is provided with a storage R9 for storing and fixing a pair of slider pieces 7.8, which are arranged with permanent magnets 10 magnetized in two width directions in between. In this storage groove 9.

Each slider piece 7.8 is fixed with its respective teeth 7a, 8a slightly protruding from the lower surface of the slider 2.

Further, a V-groove 12 is formed in the base 1 and the mover 2 along the direction of relative movement thereof.

A ball 13 for smoothly moving the mover 2 with respect to the base 1 is arranged in the groove 12.

What is the base 1 and mover 2 configured in this way?

Teeth 3a, 3b, 4a, 4b of stator core 3.4,
The slider pieces 7.8 are arranged with their peaks 7a and 8a facing each other, and the mover 2 is driven stepwise on the base 1 by exciting the stator core 3.4.

However, in the above-mentioned linear stepping motor, when the stator cores 3 and 4 are excited by the two-phase excitation force type and the mover 2 is driven in steps, the amount of movement per step is shown in Fig. 8. This caused the problem that the current situation changed drastically. Furthermore, Figure 8 shows 1
This is a plot of changes in the amount of deviation relative to the reference position (O on the vertical axis) for each step. This change in the amount of movement for each step has been a major problem because it causes trunk displacement when a linear stepping motor is used in a head feeding mechanism of a magnetic disk drive.

The cause of the change in the amount of movement per step of the linear stepping motor is from the slider pieces 7 and 8 to the stator cores 3 and 4.
It is thought that this is because the density of the magnetic flux entering each tooth portion 3a, 3b, 4a, 4b is non-uniform.

That is, the magnetic flux generated from the permanent magnet 10 held in the mover 2 of the linear stepping motor passes through the slider pieces 7 and 8 to the N of the slider piece 7 and 8 as shown in FIG.
, S has almost uniform parallel magnetic flux with respect to the facing surfaces of S, but by making the mover 2 and the base 1 face each other, the teeth 3a, 3b, 4a, 4b of the stator core and the peaks of the slider piece are 7a and 8a are arranged to face each other, since the stator core 3.4 fixed to the base 1 is made of a high magnetic permeability material, the teeth of the stator core 3a, 3b, 4a, 4h
The magnetic flux from the slider pieces 7, 8 facing the stator core is drawn into the teeth 3a, 3b, 4a, 4b, and
Teeth 3a, 3b, 4 of stator core of slider piece 7°8
Even the magnetic flux in the portions not facing a and 4b is drawn into the stator cores 3 and 4 (see Figures 3 and 4).
The density of the magnetic flux that enters the teeth 3a, 4a of the stator core is greater than the density of the magnetic flux that enters the teeth 3b, 4h.

Furthermore, the density of the magnetic flux that enters the toothed portion 3a and the density of the magnetic flux that enters the toothed portion 4a vary greatly depending on the position of the mover 2, and if the mover 2 is located biased to one side with respect to the stator cores 3 and 4. , the density of the magnetic flux that enters the teeth of the stator core on the side where the mover 2 is biased increases. That is.

As shown in Figures 3 and 4, the stator core 3
When the slider pieces 7 and 8 of the slider 2 are biased toward the toothed portion 3a, the density of the magnetic flux entering the toothed portion 3a is as follows.
It is larger than the density of the magnetic flux that enters the tooth portion 4a.

The linear stepping motor in this state is
When step driving is performed using the phase excitation force method, the density of the magnetic flux that enters the ridges 3a and teeth 4a of the stator core is different, so the propulsive force applied from the stator cores 3 and 4 to the teeth 3a and 4a becomes unbalanced. As shown in the experimental results shown in FIG. 8, this caused the amount of movement per step to vary greatly from step to step. In FIG. 8, the vertical axis shows the amount of deviation from the reference value of the movement amount for each step, and the horizontal axis shows the number of steps.

In order to solve the above-mentioned drawbacks, the present invention arranges a soft magnetic material on the side of the stator core in the moving direction of the mover to make the magnetic flux density in the stator core constant, thereby increasing the speed of one step of a linear stepping motor. This makes it possible to keep the change in the amount of movement small each time.

The present invention will be described in detail below with reference to the two drawings.

FIG. 5 shows an embodiment of the present invention in which a plurality of metal plates 14 made of soft magnetic material are adhesively fixed to the base 1 of the linear stepping motor shown in FIG.

In FIG. 5, the same reference numerals as in FIG. 1 are used for the same parts as in FIG. 1. In FIG. 5, the metal plate 14 includes the stator core 3 fixed in the storage hole 11 of the base 1
1 to 4, they are adhesively fixed to the base surfaces on both sides of the moving element 2 in the direction of movement. This metal plate 14 includes permalloy,
A soft magnetic material such as a silicon steel plate is used, and the teeth 3a of the stator core of the slider pieces 7 and 8 fixed to the slider 2 are made of a soft magnetic material such as a silicon steel plate.
, 3b, 4a, and 4b are arranged so that the magnetic flux from the portions not facing them passes through the inside of the metal plate 14, as shown in FIGS. 6 and 7. As a result, only the magnetic flux from the slider piece 7.8 facing the teeth passes through the teeth 3a, 3b, 4a, 4b of the stator core 3.4, so that the stator cores 3, 4 are approximately The magnetic flux density will be kept constant. Therefore, in this linear stepping motor, there is no thrust imbalance between the teeth 3a, 3b, 4a, and 4b of the stator core, and as shown in the experimental results in FIG. Volume fluctuations are significantly reduced. In FIG. 9, the vertical axis shows the amount of deviation from the reference value of the movement amount for each step, and the horizontal axis shows the number of steps. Furthermore, instead of using a plurality of metal plates 14, one metal plate may be adhesively fixed to both sides of the stator core.

FIG. 10 is a diagram showing a further embodiment of the present invention, in which the base 1 has the same length as the base 1 and is wider than the stator cores 3 and 4.
A metal plate 15 made of a soft magnetic material is provided with holes 16 through which the stator cores 3 and 4 protrude, and is fixed to the base 1 by adhesive.

According to this configuration, only one metal plate needs to be glued to the base 1, which simplifies assembly.
, 4 are also provided with metal plates 15 made of soft magnetic material, which also has the effect of shielding magnetic flux leakage from the stator core 3.4. FIG. 11 shows a hole 1 for protruding the stator core 3 in a soft magnetic metal plate 17 that is the same length as the base 1 and wider than the stator core 3.4.
8 and a protrusion hole 19 for the stator core 4, respectively.
In this embodiment, not only both sides of the stator core 3.4 but also the space between the stator core 3 and the stator core 4 are covered with a metal plate I7 made of a soft magnetic material. Since the magnetic flux leaking from between 4 and 4 can also be shielded, the shielding effect is better than that of the embodiment shown in FIG.

As explained above, according to the present invention, for the stator core fixed to the base of the linear stepping motor,
A soft magnetic material is placed on the moving direction side of the slider so that the density of the magnetic flux entering the stator core from the slider piece remains almost constant.

When the stator core is excited and the motor is driven step by step, the following effect is achieved: (1) Changes in the amount of movement for each step can be kept extremely small.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional linear stepping motor.
Figure 2 is a plan view showing the state of the magnetic flux of the slider piece;
4 is a side view of the same, FIG. 5 is a perspective view of the linear stepping motor according to the present invention, and FIG.
FIG. 7 is a plan view showing the state of magnetic flux of the linear stepping motor according to the present invention, FIG. 7 is a side view of the same, and FIG. FIG. 9 is a diagram showing the amount of deviation from the reference value of the amount of movement for each step of the linear stepping motor in the present invention. FIGS. 10 and 11 are plan views showing two other embodiments of the present invention. 1. Base, 2. ,,,Mover, 3,4. ,,
Stator core 7.8. ,, slider piece, 10. ,,,
Permanent magnet, 14,15.17. . A metal plate made of soft magnetic material. Patent applicant Hideharu Watanabe, Patent Attorney, Sankyo WI Machinery Co., Ltd. 9- -314- 瀝 hi'f(j 发+ 111 Rmu 吻葵 - TO-Fence Procedural Amendment (Voluntary) January 170, 1980 Patent Agency Commissioner Kazuo Wakasugi 1, Indication of the case Patent Application No. 154.978 of 1982, 2 Name of the invention Linear stepping motor 3, Relationship to the skin case involving the City of Nagano Address of patent applicant Suwa, Nagano Prefecture 5329 Shimosuwa-cho, District Name (2)
23) Sankyo Co., Ltd. 11'7t J Current Sekisakusho Representative
Person: Kubo [Excuse 4, Agent Address: 1-17 Shinbashi, Minato-ku, Tokyo 2°C Outdated Description of the Invention (Paper and Drawings\-1/Attachment 1, Specification, Page 4, No. 15) In the 17th line from the 1st line, it says ``Pull in...becomes more personable than the density.1''.
The magnetic flux density within h is non-uniform. For example, when the slider piece 7.8 and the stator cores 3, 4 are in the positional relationship shown in FIGS. 3 and 4, the density of the magnetic flux that enters the teeth 3b, 4a of the stator core is
It is larger than the density of magnetic flux entering +. ” he corrected. 2. Correct the figures 6 and 7 of the drawings as shown in the attached figures. More-1-

Claims (1)

[Scope of Claims] A stator core held on a base with its peaks exposed, and a mover disposed opposite to the base. In a linear stepping motor having a slider piece held by the mover and having teeth facing the teeth of the stator core, with respect to the stator core,
A linear stepping motor characterized in that a soft magnetic material is arranged on the moving direction side of the moving element.