WO2014020695A1

WO2014020695A1 - Linear motor

Info

Publication number: WO2014020695A1
Application number: PCT/JP2012/069443
Authority: WO
Inventors: 憲昭吉村
Original assignee: 株式会社安川電機
Priority date: 2012-07-31
Filing date: 2012-07-31
Publication date: 2014-02-06
Also published as: JPWO2014020695A1; KR20150027790A; CN204334284U; JP5472489B1

Abstract

The present invention provides a linear motor that simultaneously achieves cogging reduction and high thrust. This linear motor (1) is equipped with: a field magnet (3) wherein multiple permanent magnets (31) are arranged in a row with alternating poles; and an armature (2) which has multiple teeth (24) which are arranged so as to face the field magnet (3) with a space (P) therebetween, a yoke section (25) for connecting the multiple teeth (24) together, and winding wires (23) respectively wound around the multiple teeth (24). The multiple teeth (24) face the field magnet (3) at tip sections (24t) via the space (P) and are connected to the yoke section (25) at rear end sections (24e). Among the multiple teeth (24), a non-end tooth (24b), that is, a tooth not positioned on either end, is positioned such that a space (P) formed between the field magnet (3) and the non-end tooth (24b) is larger than a space (P) formed between the field magnet (3) and teeth (24a) positioned on either end. Cross-sectional areas near the tip sections (24t) of all of the multiple teeth (24) or non-end teeth (24b) are smaller than cross-sectional areas near the rear end sections (24e) thereof.

Description

Linear motor

The present invention relates to a linear motor.

Conventionally, linear motors are used for table feed in semiconductor manufacturing equipment and machine tools. The linear motor has a field in which a plurality of permanent magnets are linearly arranged, and an armature facing the field, and one of the field and armature functions as a stator, When the other functions as a mover, the field and the armature move relative to each other. The armature has a plurality of teeth that face each other via a field and a gap, and a yoke portion that connects rear end portions of the plurality of teeth. In order to reduce cogging when the number of teeth is three, a linear motor having an armature in which a recess is formed at the tip of a central tooth has been proposed (see, for example, Patent Document 1).

JP-A-7-99767

In the linear motor, cogging is required to be further reduced. If the teeth of the armature of the linear motor are made thin (that is, the cross-sectional area of the teeth is reduced), cogging can be reduced, but the thrust is reduced instead. In order to improve the thrust, it is effective to make the teeth thicker, but then cogging will increase. Therefore, it is desired to provide a linear motor with low cogging and high thrust.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a linear motor that achieves both low cogging and high thrust.

In order to solve the above-described problems, a linear motor as an exemplary aspect of the present invention includes a field in which a plurality of permanent magnets are arranged in rows so as to have different polarities, and a field and a gap. A plurality of teeth arranged so as to face each other, a yoke portion connecting the plurality of teeth, and an armature having a winding wound around each of the plurality of teeth. The plurality of teeth are opposed to the field through the air gap at the front end portion, and are connected to the yoke portion at the rear end portion. One of the non-end teeth that is not located at both ends of the plurality of teeth is arranged such that a gap between the teeth is larger than that of the teeth located at both ends. The cross-sectional area in the vicinity of the front end portion of all of the plurality of teeth or the non-end portion teeth is smaller than the cross-sectional area in the vicinity of the rear end portion of the teeth.

All of the plurality of teeth or the non-end teeth may have a stepped portion whose cross-sectional area changes sharply at any position from the rear end to the front end.

The length from the rear end portion to the stepped portion may be in the range of 1/6 or more and 2/3 or less of the length from the rear end portion to the front end portion.

The length from the rear end portion to the stepped portion may be the same in the plurality of teeth having the stepped portion.

All of the plurality of teeth or the non-end portion teeth may have a tapered portion whose cross-sectional area changes gently at any position from the rear end portion to the front end portion.

The length of the non-end teeth from the rear end portion to the front end portion may be shorter than the teeth located at both ends.

The cross-sectional area of the tip portion of the non-end teeth may be smaller than the cross-sectional area of the tip portion of the teeth positioned at both ends.

The shape at the rear end of the plurality of teeth may be the same. The end surface of the front end portion of the non-end tooth may be a curved surface. Further, the total number of the plurality of teeth may be three.

Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

According to the present invention, both low cogging and high thrust can be achieved. Therefore, a linear motor that can be smoothly and powerfully driven can be provided.

It is a figure which shows the external appearance perspective view and side of the linear motor which concerns on Embodiment 1. FIG. FIG. 2 is a structural diagram illustrating an outline of an internal structure of an armature and a field of the linear motor illustrated in FIG. 1. It is an internal structure figure of the armature of the conventional linear motor. 6 is an internal structure diagram of an armature according to Embodiment 2. FIG. 6 is an internal structure diagram of an armature according to Embodiment 3. FIG. FIG. 6 is an internal structure diagram of an armature according to a fourth embodiment. 6 is an internal structure diagram of an armature according to Modification 1. FIG. 10 is an internal structure diagram of an armature according to Modification 2. FIG. 10 is an internal structure diagram of an armature according to Modification 3. FIG. It is an internal structure figure of the armature which concerns on the comparison type A. It is an internal structure figure of the armature concerning comparative type B. It is a graph which shows the relationship between the electric current in an Example, and thrust. It is a graph which shows the relationship between the position of the needle | mover in an Example, and a cogging thrust.

[Embodiment 1]
Hereinafter, the linear motor according to the first embodiment will be described with reference to the drawings. FIG. 1 is an external perspective view and a side view of a linear motor 1 according to the first embodiment. The linear motor 1 has an armature 2 and a field 3. The armature 2 functions as a mover, and the field 3 functions as a stator. The armature 2 can move relative to the field 3 in the direction of arrow A. The field 3 may extend linearly along the direction of arrow A, for example. The field 3 may have a curved portion within a range in which the armature 2 can be relatively moved.

The armature 2 has an armature coil 21 inside. The field 3 has a plurality of permanent magnets 31 (see FIG. 2) having different polarities inside. The armature 2 and the field 3 are arranged so that the armature core 22 of the armature coil 21 and the permanent magnet 31 are opposed to each other via a gap (magnetic gap). The armature 2 is guided by a guide structure (not shown) of the field 3 so that a gap is secured even during relative movement.

FIG. 2 is a structural diagram showing an outline of the internal structure of the armature 2 and the field 3. FIG. 2 is a view of the linear motor 1 cut along a plane X shown in FIG. For ease of explanation, only the main configuration is shown in FIG. 2, and the other components are not shown.

In the field 3, a plurality of permanent magnets 31 are arranged in a row. The permanent magnets 31 are alternately arranged so as to have different polarities, that is, as “· S · N · S · N ·”.

The armature coil 21 of the armature 2 is configured by winding a winding 23 around an armature core 22. Specifically, a winding 23 is wound around a bobbin (not shown), and the bobbin is inserted into a tooth 24 as a part of the armature core 22. 24 (or armature core 22) may be expressed as “winding 23 is wound around”. The armature core 22 has a plurality of teeth 24 that project in a tooth shape toward the field 3 and a yoke portion 25 that connects the teeth with a rear end portion 24e. The tip 24t of the tooth 24 is opposed to the field 3 via the air gap P. The armature core 22 is generally made of a magnetic material. Although the number of teeth 24 in the armature core 22 is not particularly limited, in the first embodiment, the armature core 22 has three teeth 24.

The winding 23 wound around the three teeth is connected to a three-phase AC power source. When currents having different phases (U-phase, V-phase, W-phase) are supplied to these three windings 23, the magnetic field generated by the armature 2 and the magnetic field generated by the permanent magnet 31 of the field 3 are used. The armature 2 relatively moves on the field 3.

The three teeth 24 have end teeth 24a disposed at both ends and non-end teeth 24b not positioned at both ends. In the first embodiment, the non-end portion tooth 24b is a central one. As shown in FIG. 3, in the conventional linear motor, the end teeth 124a and the non-end teeth 124b have the same shape and size. Further, both the end teeth 124a and the non-end teeth 124b have the same shape and the same cross-sectional area from the rear end portion connected to the yoke portion 125 to the front end portion facing the field.

However, in the linear motor 1 according to the first embodiment, the end teeth 24a and the non-end teeth 24b have different shapes. The teeth 24 according to the first embodiment will be described assuming that the cross-sectional shape is a quadrangular shape. The non-end portion teeth 24b have a shorter protruding length (length from the rear end portion 24e to the front end portion 24t) than the end teeth 24a. The gap P in the non-end portion tooth 24b is larger than the gap P in the end portion tooth 24a. The magnetic resistance between the armature 2 and the field 3 in the non-end tooth 24b becomes larger than the magnetic resistance in the end tooth 24a, and cogging (vibration) occurs when the armature 2 moves along the extending direction of the field 3. ) Is reduced.

Both the end teeth 24 a and the non-end teeth 24 b have stepped portions 26. The stepped portion 26 is a portion where the cross-sectional area of the tooth 24 changes sharply at any position from the rear end portion 24e to the front end portion 24t. The cross-sectional area (tooth width Te × teeth stacking thickness) in the portion from the rear end portion 24e to the stepped portion 26 is greater than the cross-sectional area (teeth width Tt × tooth stacking thickness) in the portion from the stepped portion 26 to the tip end portion 24t. Is also big. Since the cross-sectional area on the rear end portion 24e side is large and the cross-sectional area on the front end portion 24t side is small, it is possible to achieve both a large motor thrust and a reduction in cogging.

The position of the stepped portion 26 is not limited, but the length from the rear end 24e to the stepped portion 26 is preferably in the range of 1/6 to 2/3 of the protruding length of the tooth 24. It is also preferable that the position of the stepped portion 26 in the end tooth 24a (the length from the rear end portion 24e to the stepped portion 26) and the position of the stepped portion 26 in the non-end portion tooth 24b are the same.

The bobbin for the winding 23 is inserted into the rear end 24e side of each tooth 24. It is preferable that the cross-sectional shape and size in the vicinity of the rear end portion 24e of the end tooth 24a are the same as the cross-sectional shape and size in the vicinity of the rear end portion 24e of the non-end portion tooth 24b. Thereby, the bobbin of the same dimension can be used for the end teeth 24a and the non-end teeth 24b. In the first embodiment, the cross-sectional shape and size in the vicinity of the tip portion 24t of the end tooth 24a are the same as the cross-sectional shape and size in the vicinity of the tip portion 24t of the non-end portion tooth 24b.

As described above, when the configuration of the armature 2 according to the first embodiment is summarized, the three teeth 24 are configured to have two end teeth 24a and one non-end portion tooth 24b. Each tooth 24 corresponds to three phases of U phase, V phase, and W phase. The non-end portion teeth 24b are shorter than the end portion teeth 24a. The gap P in the non-end tooth 24b is larger than the gap P in the end tooth 24a. The end teeth 24a and the non-end teeth 24b have a large cross-sectional area (tooth width Te x teeth stacking thickness) on the rear end 24e side and a small cross-sectional area (tooth width Tt x teeth stacking thickness) on the front end 24t side. In addition, a stepped portion 26 whose cross-sectional area changes sharply in the middle of the protruding length is provided. The end teeth 24a and the non-end teeth 24b are common in the position of the stepped portion 26, the cross-sectional area and shape in the vicinity of the rear end portion 24e, and the cross-sectional area and shape in the front end portion 24t. The length from the rear end portion 24e to the stepped portion 26 is 1/6 to 2/3 of the protruding length of the tooth 24.

Since the armature 2 has such a configuration, the linear motor 1 according to the first embodiment solves the difficult problem of achieving both sufficiently large thrust characteristics and low cogging.

The cross-sectional area in the vicinity of the rear end portion 24e of the non-end portion teeth 24b is made smaller than the cross-sectional area in the vicinity of the rear end portion 24e of the end portion teeth 24a, thereby reducing the magnetic resistance in the non-end portion teeth 24b. It can be made larger than the magnetoresistance in Making the cross-sectional area in the vicinity of the tip 24t of the non-end tooth 24b smaller than the cross-sectional area in the vicinity of the tip 24t of the end tooth 24a also contributes to an increase in magnetic resistance in the non-end tooth 24b.

The position of the stepped portion 26 in the end tooth 24a and the position of the stepped portion 26 in the non-end tooth 24b are not necessarily the same. It is sufficient that the gap P in the non-end tooth 24b is larger than the gap P in the end tooth 24a, and the protruding length of the non-end tooth 24b is not necessarily shorter than the protruding length of the end tooth 24a.

[Embodiment 2]
FIG. 4 is an internal structure diagram of the armature 202 of the linear motor according to the second embodiment. In this armature 202, the teeth 224 (224a, 224b) have a tapered portion 226 instead of a stepped portion. The tapered portion 226 is a portion where the cross-sectional area of the teeth 224 changes gently at any position from the rear end portion 224e to the front end portion 224t. The taper portion 226 gradually reduces the cross-sectional area of the teeth 224 from the rear end 224e to the front end 224t, and the cross-sectional area in the vicinity of the front end 224t is reduced. Similar to the linear motor 1 of the first embodiment, the linear motor according to the second embodiment also achieves both high thrust and low cogging.

In addition, about the other structure in Embodiment 2, since it is the same as that of Embodiment 1, description is abbreviate | omitted.

[Embodiment 3]
FIG. 5 is an internal structure diagram of the armature 302 of the linear motor according to the third embodiment. In this armature 302, the tip end portion 324t of the non-end portion teeth 324b (324) has a concave (curved) shape. Thereby, the magnetic resistance in the non-end tooth 324b can be further increased than the magnetic resistance in the end tooth 324a (324).

In addition, about the other structure in Embodiment 3, since it is the same as that of Embodiment 1, description is abbreviate | omitted.

[Embodiment 4]
FIG. 6 shows the internal structure of the armature 402 of the linear motor according to the fourth embodiment. The armature 402 has a total of six teeth 424 including two end teeth 424a and four non-end teeth 424b. In the fourth embodiment, two non-end teeth 424b1 closer to the center among the plurality of non-end teeth 424b have the same configuration as the non-end teeth 24b in the first embodiment. The other two, that is, the non-end portion teeth 424b2 positioned outside the two non-end portion teeth 424b1 closer to the center have the same configuration as the end portion teeth 424a. The end teeth 424a have the same configuration as the end teeth 24a in the first embodiment.

In addition, about the other structure in Embodiment 4, since it is the same as that of Embodiment 1, description is abbreviate | omitted.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

For example, as in Modification 1 shown in FIG. 7, the end teeth 424a and the two non-end teeth 424b1 closer to the center have the same configuration as that of the fourth embodiment, and are arranged outside the non-end teeth 424b1. The gap Pb2 between the two non-end teeth 424b2 positioned may be intermediate between the gap Pa in the end teeth 424a and the gap Pb1 in the non-end teeth 424b1 closer to the center.

As in Modification 2 shown in FIG. 8, the end teeth 424 a have the same configuration as the end teeth 24 a in the first embodiment, and two ends teeth are positioned outside the two non-end teeth 424 b 1 closer to the center. The non-end portion teeth 424b2 have the same configuration as the non-end portion teeth 24b in the first embodiment. It may be an intermediate size.

As in Modification 3 shown in FIG. 9, the end teeth 424a and the two non-end teeth 424b1 closer to the center have the same configuration as the end teeth 424a in the first embodiment, and the non-end teeth 424b1 The two non-end portion teeth 424b2 located outside may have the same configuration as the non-end portion teeth 24b in the first embodiment. That is, the gap Pa in the end teeth 424a and the gap Pb1 in the non-end teeth 424b1 may be the same size, and the gap Pb2 in the non-end teeth 424b2 may be larger than them.

How large the gap in the non-end teeth is to be larger than the gap in the end teeth, whether the gaps in the non-end teeth are all the same, and the gap in any non-end teeth As to whether the gap is larger than the non-end tooth, an optimum configuration is selected according to design circumstances such as which phase (U phase, V phase, W phase) is assigned to each tooth. Of course, the number of the non-end portion teeth 424b may be one in the first embodiment, four in the fourth embodiment, or more.

[Example]
A comparative experiment using the linear motor 1 according to the first embodiment was performed. The comparison targets are the following two types of linear motors.

Comparison type A: As in the first embodiment, the non-end tooth A1 was shortened to make the gap P1 in the non-end tooth A1 larger than the gap P2 in the end tooth A2. No stepped portion is provided, and each of the teeth A1 and A2 has a quadrangular shape with no change in cross-sectional area. The cross-sectional area is the cross-sectional area at the tip 24t of the tooth 24 in the first embodiment (tooth width Tt × tooth stacking thickness). ) (See FIG. 10).

Comparison type B: As in the first embodiment, the non-end tooth B1 was shortened so that the gap P1 in the non-end tooth B1 was larger than the gap P2 in the end tooth B2. No stepped portion is provided, and each of the teeth B1 and B2 has a quadrangular shape with no change in cross-sectional area. The cross-sectional area is the cross-sectional area at the rear end portion 24e of the tooth 24 in the first embodiment (tooth width Te × tooth stack). Thickness) (see FIG. 11).

The relationship between the current and the thrust when the three linear motors (Embodiment 1, comparison type A, comparison type B) are driven is shown in the graph of FIG. 12, and the relationship between the position of the mover and the cogging thrust is shown in FIG. It was shown in the graph. 12 and 13, it can be seen that the linear motor of the first embodiment has a thrust characteristic equivalent to that of the comparative type B and has a cogging characteristic equivalent to that of the comparative type A.

Arrow: A
Gaps: P, P1, P2, Pa, Pb1, Pb2
Plane: X
Linear motor: 1
Armature: 2,202,302,402
Armature coil: 21
Armature core: 22
Winding: 23
Teeth: 24, 224, 324
End teeth: 24a, 124a, 224a, 324a, 424a, A2, B2
Non-end teeth: 24b, 124b, 224b, 324b, 424b, 424b1, 424b2, A1, B1
Rear end: 24e, 224e
Tip: 24t, 224t, 324t
Relay part: 25, 125
Stepped part: 26
Tapered portion: 226
Field: 3
Permanent magnet: 31

Claims

A magnetic field in which a plurality of permanent magnets are arranged in a row so as to have different polarities alternately;
A plurality of teeth arranged so as to be opposed to the field through a gap, a yoke portion connecting the plurality of teeth, and an armature having a winding wound around each of the plurality of teeth; With
The plurality of teeth are opposed to the field through the gap at the front end, and are connected to the yoke portion at the rear end.
Any of the non-end teeth that are not located at both ends of the plurality of teeth is arranged so that a gap between the teeth is larger than that of the teeth located at both ends,
A linear motor in which the cross-sectional area of the plurality of teeth or the non-end portion teeth in the vicinity of the front end portion is smaller than the cross-sectional area of the teeth in the vicinity of the rear end portion.
2. All of the plurality of teeth or the non-end portion teeth have a stepped portion whose cross-sectional area changes sharply at any position from the rear end portion to the tip end portion. The linear motor described in 1.
The linear motor according to claim 2, wherein a length from the rear end portion to the stepped portion is in a range of 1/6 or more and 2/3 or less of a length from the rear end portion to the tip end portion. .
The linear motor according to claim 2 or 3, wherein a length from the rear end portion to the stepped portion is the same in a plurality of teeth having the stepped portion.
All of the plurality of teeth, or the non-end portion teeth, have a tapered portion whose cross-sectional area gradually changes at any position from the rear end portion to the tip end portion. The linear motor described.
The linear motor according to any one of claims 1 to 5, wherein the non-end portion teeth are shorter in length from the rear end portion to the tip end portion than teeth positioned at the both ends.
The linear motor according to any one of claims 1 to 6, wherein a cross-sectional area of a tip portion of the non-end tooth is smaller than a cross-sectional area of a tip portion of the teeth positioned at both ends.
The linear motor according to any one of claims 1 to 7, wherein shapes of rear ends of the plurality of teeth are the same.
The linear motor according to any one of claims 1 to 8, wherein an end surface of a tip portion of the non-end tooth is a curved surface.
The linear motor according to any one of claims 1 to 9, wherein a total number of the plurality of teeth is three.