JPH053660A - Linear step motor - Google Patents

Abstract

PURPOSE:To prevent occurrence of third higher harmonic in the thrust waveform of mover. CONSTITUTION:Core 21 of a mover 2 comprises first and second core sections 21a, 21b shifted from each other by one-sixth of the pitch P of slider tooth 2a in the advancing direction. Since third higher harmonics in the thrust waveforms of the first and second core sections 21a, 21b have reverse poralities, they are offset each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear step motor.

[0002]

2. Description of the Related Art Conventionally, a linear stepping motor shown in FIG. 5 has been known, which is composed of a stator 11 and a mover 12.

The stator 11 is formed of a magnetic material in the form of an elongated body, and is provided with a number of comb-shaped scale teeth 11a protruding in the longitudinal direction at a constant pitch P.

The mover 12 has two protruding pieces 13a, which are formed by laminating a plurality of U-shaped thin steel plates which are insulated from each other.
Iron core 13 formed in a U shape having 13b and its protruding piece
It consists of an exciting coil 14 wound around each of 13a and 13b, and the tip of each protruding piece 13a and 13b has a comb tooth-shaped slider facing the scale tooth 11a at the same pitch P as the scale tooth 11a. Four teeth 12a are provided so as to project.

In the mover 12, thrust is applied between the scale teeth 11a and the slider teeth 12a by a magnetic flux generated by applying an alternating current to the exciting coil 14 at a predetermined timing, so that the length of the stator 11 increases. It is designed to proceed along the direction.

[0006]

In the above-described conventional linear step motor, the thrust waveform acting on the mover 12 is distorted because it contains the higher harmonic component, especially the third harmonic. There is. For this reason, it is not possible to perform accurate positioning using microstep drive or the like.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a linear step motor capable of obtaining a thrust waveform of a mover while preventing generation of a third harmonic. ..

[0008]

In order to solve the above problems, a linear step motor according to the present invention includes a stator provided with comb-shaped scale teeth at a constant pitch in the longitudinal direction, and a scale tooth. In a linear step motor having an iron core provided with comb-teeth-shaped slider teeth facing the scale teeth at the same pitch and advancing in the longitudinal direction of the stator, the iron core has an advancing direction. Is composed of two first and second iron core portions that are separated by 1/6 of the pitch.

[0009]

According to the linear stepping motor of the present invention, since the iron core of the mover is composed of two first and second iron core portions that are offset by ⅙ pitch in the traveling direction, 1
Since the positive and negative polarities of the third harmonics of the thrust waveform acting on the second iron core and the second harmonic of the second iron core cancel each other out, their occurrence can be prevented.

[0010]

1 to 4 show an embodiment of the present invention. In describing the present embodiment, first, the basic configuration of a linear step motor to which the present invention is applied will be described with reference to FIGS. 2 and 3.

Reference numeral 1 denotes a stator, which is made of a magnetic material and is formed in an elongated shape, and a plurality of comb-tooth-shaped scale teeth 1a are provided at a constant pitch P in the longitudinal direction thereof.
Then, two of the stators 1 are arranged at predetermined intervals,
Both scale teeth 1a face each other and face each other
Are arranged in parallel so that the pitch P does not shift.

Reference numeral 2 denotes a mover, which is formed by stacking a plurality of H-shaped thin steel plates insulated from each other to form four protruding pieces 21a,
It comprises an iron core 21 formed in an H shape having 21b, 21c, 21d, and an exciting coil 22 wound around each of the projecting pieces 21a, 21b, 21c, 21d. , 21b, 21c, 21d are provided with four comb-teeth-shaped slider teeth 2a facing the scale teeth 1a at the same constant pitch P as the scale teeth 1a of the stator 1 protruding from each tip. .. The relative pitch deviation between the scale tooth 1a of the stator 1 and the slider tooth 2a of the mover 2 is 1/2 P at the protruding piece 21b, where P is the fixed pitch and 0 at the protruding piece 21a. 1 / 4P for protruding piece 21c, protruding piece 21d
Is set to be -1 / 4P, and two movers 2 configured as described above are arranged in the longitudinal direction of the stator 1.

In both of the two movers 2, as shown in FIG. 3, only two of the exciting coils 22 wound around each of the projecting pieces 21a, 21b, 21c and 21d are constantly subjected to alternating current. By causing the magnetic flux to flow to generate a so-called two-phase motor excitation, a thrust acts between the scale teeth 1a and the slider teeth 2a to propel it along the longitudinal direction of the stator 1. In FIG. 3, A, B, C and D correspond to the protruding pieces 21a, 21b, 21c and 21d, respectively.

Next, the structure of the iron core 21 of the mover 2 which is a feature of this embodiment will be described. As shown in FIG. 1, the iron core 21 is 1 / 6P in the moving direction of the mover 2, that is, in the direction orthogonal to the protruding direction of the slider teeth 2a at the center of the thickness of a plurality of H-shaped thin steel plates laminated. Slide the first iron core 21
It is divided into two parts, a and the second iron core portion 21b, and they are fixedly formed.

The relationship between the above configuration and the thrust force waveform of the mover 2 will be described with reference to FIG. In the figure, the horizontal axis is the traveling stroke, and the vertical axis is the thrust. The thrust force waveforms acting on the protruding pieces 21a, 21b, 21c, 21d have the same shape, and one of them is shown. Now, the first iron core portion 21a and the second iron core portion 21b
When and are not divided into two, their waveforms are the same, and let it be A ₀ (dashed-dotted line). From that state, as shown by the arrow, the first iron core portion 21a is shifted to the right in the traveling direction by 1 / 12P to be A ₁ (solid line),
The second iron core 21b to the left, which is the opposite direction to the traveling direction.
If / 12P is shifted to A ₂ (broken line), A ₁ and A ₂ are 1
It is offset by / 6P, and as described above, this represents the configuration in which the first iron core portion 21a and the second iron core portion 21b are displaced by 1 / 6P as a thrust waveform.

By the way, A ₁ and A ₂ include the third harmonic waves B ₁ and B ₂ , respectively, and the two central waveforms shown by the slanted lines in them have positive and negative signs opposite to each other and therefore cancel each other out. Therefore, the third harmonic can be reduced accordingly.

In this embodiment, the third harmonic waves B ₁ and B ₂
The two waveforms at both ends of are not removed, but this is because the two-phase motor excitation is performed so that the two movers 2 travel with the same thrust waveform, and the excitation timing of the two movers 2 is If it is changed to a 4-phase motor structure, the third
Harmonics can also be removed.

[0018]

According to the linear step motor of the present invention, since the iron core of the mover is composed of two first and second iron core portions which are deviated by 1/6 pitch in the traveling direction, 1
Since the positive and negative polarities of the third harmonic waves of the thrust waveforms acting on the second iron core portion and the second iron core portion cancel each other out, their occurrence can be prevented.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing a main part of an embodiment of the present invention.

FIG. 2 is a front view showing the overall structure of the above.

FIG. 3 is a diagram showing a waveform of an exciting current in the above.

FIG. 4 is a diagram showing a thrust waveform of the same.

FIG. 5 is a front view showing the overall structure of a conventional example.

[Explanation of symbols]

 1 Stator 1a Scale teeth 2 Mover 2a Slider teeth 21 Iron core 21a First iron core 21b Second iron core P P Constant pitch

Claims (1)

Claim: What is claimed is: 1. A stator provided with comb-shaped scale teeth at a constant pitch in the longitudinal direction, and a comb-shaped slider tooth facing the scale teeth at the same pitch as the scale teeth. A mover having an iron core provided and advancing in the longitudinal direction of the stator;
In a linear step motor having, the iron core is
A linear stepping motor comprising two first and second iron core portions that are separated by 1/6 of the pitch in the traveling direction.