JP2002119040A - Linear motor - Google Patents

Abstract

(57) [Problem] To provide a linear motor capable of suppressing generation of cogging thrust. SOLUTION: A field iron core in which a plurality of permanent magnets 2 constituting a field pole are arranged in a straight line is arranged, and an armature winding 5 is arranged oppositely to a row of the permanent magnets 2 via a magnetic gap. A linear motor having an armature 4 composed of an armature core 4, wherein one of the field pole and the armature 3 is a stator and the other is a movable element, and is relatively driven. The core blocks 1A and 1B are divided in the thrust direction, a gap is provided between the core blocks, and a magnetic spacing member 6 is inserted into the gap between the core blocks. Thereby, the cogging thrust between the field pole and the teeth 4b or the cogging thrust due to the end effect at both ends of the field iron core 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 linear motor used in a transport system for FA equipment, for example, a table feed of a machine tool or a stepper drive mechanism of a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a linear motor used for a transport system of an FA device, for example, a table feed of a machine tool or a stepper drive mechanism of a semiconductor manufacturing apparatus. FIG. 7 is a side sectional view of a conventional linear motor. In the drawings, a moving magnet type linear motor will be described as an example. In the figure, reference numeral 10 denotes a plate-shaped field iron core, 2 denotes a plurality of permanent magnets constituting field poles having different polarities alternately on the field iron core 10, and 3 denotes an electric machine opposed to the magnetic pole surface of the permanent magnet 2 via a gap. The armature 4 is an armature iron core, which is formed by punching out an electromagnetic steel sheet into a comb-like shape to form a tooth 4a and a yoke 4b.
5 are armature windings in which an armature iron plate formed by laminating and fixing is fixed. Here, the teeth 4a provided on the armature core 4 are such that when the number of phases of the armature winding 5 is n, the number of field poles is P, and the number of teeth per field pole is q,
The armature winding 5 is wound around the slots 4c located between the teeth 4a with the number of n × P × q provided over the entire length of the field core 10 in the traveling direction. In the linear motor having such a configuration, the field iron core 10 having the field poles is used as a mover, the armature 3 is used as a stator, and the field iron core 10 runs in the longitudinal direction of the armature 3. ing.

[0003]

In the prior art, a magnetic circuit is generally formed between the teeth 4a formed on the armature core 4 and the permanent magnets 2 serving as field poles.
A cogging thrust is generated due to a change in magnetic resistance caused by the opening shape of c, and this cogging thrust has contributed to a thrust variation that occurs when the field pole and the armature 3 move relative to each other. Further, since the magnetic circuits formed at both ends of the field iron core 10 are open, a cogging thrust due to the end effect is also generated, which also contributes to the thrust fluctuation. The present invention has been made to solve the above problems, and has as its object to provide a linear motor capable of suppressing generation of cogging thrust.

[0004]

In order to solve the above-mentioned problems, the present invention according to claim 1 has a field magnet in which a plurality of permanent magnets constituting a field pole are alternately arranged in a line so as to have alternately different polarities. An iron core, an armature composed of an armature core disposed so as to face the permanent magnet array via a magnetic gap and an armature winding in which a coil is wound around a slot of the armature core. A linear motor having one of the field pole and the armature as a stator and the other as a mover, wherein the field pole and the armature run relatively to each other. And the core block is divided in the thrust direction, a gap is provided between the core blocks, and a spacing member of a magnetic material is inserted into the gap between the core blocks. According to a second aspect of the present invention, in the linear motor according to the first aspect, the number of divisions of the core block is n, the length of one core block is L, and the number P of field poles included in the entire core block is P. LCM is the least common multiple of the number of teeth S contained in one iron core block.
(P, S), when a natural number not including a multiple of the number of divisions of the core block is represented by m ₁ , the length of the interval piece is

[0005]

(Equation 7)

[0006] According to a third aspect of the present invention, in the linear motor according to the first aspect, the number of divisions of the iron core block is n, the length of one iron core block is L, and the number of field poles included in the entire iron core block is P, and a natural number that does not contain a multiple of the division number of the core block when expressed in m _1, the length of the distance piece

[0007]

(Equation 8)

[0008] It is shown by. According to a fourth aspect of the present invention, in the linear motor according to the first aspect, the number of divisions of the iron core block is n, the length of one iron core block is L, and the number P of field poles included in the entire iron core block is P.
And the least common multiple of the number of teeth S included in one iron core block and LCM (P, S),
Using the coefficient m _{1 according} to claim ₂ and the coefficient m _{2 according} to claim 3, the relationship between the coefficient m ₁ and the coefficient m ₂ is:

[0009]

(Equation 9)

It is assumed that the following expression is satisfied, and the length of the interval piece is determined using the coefficient m _1.

[0011]

(Equation 10)

This is represented by the following equation. According to a fifth aspect of the present invention, in the linear motor according to the first aspect, the number of divisions of the iron core block is n, the length of one iron core block is L, and the number of field poles included in the entire iron core block is P, wherein the natural number that does not contain a multiple of the division number of the core blocks in a case where expressed in m _1, claim 1 factor described m ₁
With claim 2 coefficients according m ₂ and the relationship of the coefficients m ₁ and the coefficient m ₂ is,

[0013]

[Equation 11]

It is assumed that the following expression is satisfied, and the length of the interval piece is determined by using the coefficient m _2.

[0015]

(Equation 12)

This is expressed by the following equation.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a linear motor according to a first embodiment of the present invention. 2A and 2B show characteristics according to the first embodiment, wherein FIG. 2A shows the cogging thrust caused by the field poles and the teeth generated in each iron core block, and FIG. 2B shows the cogging thrust caused by the end effect generated in each iron core block. is there. In the present invention, the same components as those in the related art are denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described. In the figure, 1A is a first iron core block, 1B is a second iron core block, and 6 is a spacing piece. The differences between the present invention and the prior art are as follows. The field core is composed of the first core block 1A and the second core block 1.
B and placed in the thrust direction, and the iron core blocks 1A, 1
B, a gap is provided between the core blocks, and a spacing member 6 made of a magnetic material is inserted into the gap between the iron core blocks. The number of divisions of the core block is n, the length of one core block is L, the number P of field poles included in the entire core block, the number S of the teeth 4b included in one core block, the number P of the magnetic poles and The least common multiple of the number S of teeth is LCM (P, S), and a natural number not including a multiple of the number of divisions of the core block is a coefficient m _1.
When expressed by, the length L _C of the spacing piece 6 is derived by Expression (1).

[0018]

(Equation 13)

In the linear motor shown in FIG. 1, the number n of divisions of the iron core block is 2, the number of magnetic poles P of the field magnet in the entire iron core block is 4, and the number S of teeth 4a in one iron core block is S.
In this case, when the coefficient m ₁ = 1 and the length L _C of the interval piece 6 is obtained from the equation (1), L /
It becomes 12. The phase difference of the induced voltage induced in the armature winding 5 by the first core block 1A and the second core block 1B is 60 °. Therefore, the phase band indicating the arrangement of the armature windings 5 is as shown in FIG. In the linear motor having the phase band of the armature winding 5, the cogging thrust between the field poles of the iron core blocks 1A and 1B and the teeth 4a is as shown in FIG. 2A, and the cogging thrust is canceled. . The cogging thrust due to the end effect is shown in FIG.
As shown in (b), the cogging thrust increases.
Since the first embodiment is configured as described above, it is possible to eliminate the thrust fluctuation generated when the field pole and the armature 3 move relative to each other, and when the cogging thrust due to the interaction between the field pole and the teeth 4a of the armature is large. It is an effective means.

Next, a second embodiment of the present invention will be described. FIG. 3 is a sectional view of a linear motor showing a second embodiment of the present invention, and FIG. 4 shows characteristics according to the second embodiment. FIG. 3 (a) shows field poles generated in each iron core block. The cogging thrust due to the teeth, and (b) is the cogging thrust due to the end effect generated in each iron core block. It is the same that a gap is provided between each core block and a spacing member 6 of a magnetic material is inserted into the gap between the core blocks. The differences between the second embodiment and the first embodiment are as follows. That is, the field iron core is divided into a first iron core block 1A, a second iron core block 1B, and a third iron core block 1C, and is arranged in the thrust direction. When the number of divisions of the core block is represented by n, the number of field poles P included in the entire core block, and a natural number not including a multiple of the division number of the core block by m ₂ , the spacing piece 6
The length L _CE derived by Equation (2).

[0021]

[Equation 14]

The linear motor of FIG. 3, since the case 3 the division number n of the core block, the number of magnetic poles P of the field magnetic in the entire core blocks of 6, at this time, as coefficients m ₂ = 1,
When the length L _CE of the interval piece 6 is obtained from the equation (2), it becomes L / 6. 1st core block 1A, 2nd core block 1B,
The phase difference between the induced voltages induced in the armature winding 5 by the third core block 1C is 120 °. Therefore, the phase band indicating the arrangement of the armature windings 5 is as shown in FIG. In the linear motor having the phase band of the armature winding 5, the cogging thrust between the field poles of each of the iron core blocks 1A to 1C and the teeth 4a is as shown in FIG. It becomes big because there is no.
Further, the cogging thrust due to the end effect is as shown in FIG. 4B, and the cogging thrusts cancel each other. Since the second embodiment has such a configuration, it is possible to eliminate the fluctuation of the thrust generated in the magnetic circuit formed at both ends of the iron core block, and this is an effective means when the cogging thrust due to the end effect is large.

Next, a third embodiment will be described. FIG. 5 is a side sectional view of a linear motor showing a third embodiment of the present invention.
Shows the characteristic according to the third embodiment,
(A) is the cogging thrust generated by the field poles and the teeth generated in each iron core block, and (b) is the cogging thrust generated by the end effect generated in each iron core block. It is the same that a gap is provided between each core block and a spacing member 6 of a magnetic material is inserted into the gap between the core blocks. The differences between the third embodiment and the first and second embodiments are as follows. Using the coefficient m ₁ described in the first embodiment and the coefficient m ₂ described in the second embodiment, m ₁ and m ₂ are determined so that the length L _C = L _{CE of the} interval piece 6. The relationship between m ₁ and m ₂ at this time is expressed by equation (3).

[0024]

(Equation 15)

In equation (3), for example, as shown in FIG. 3, the number S of teeth 4a in one iron core block is 6, and the number P of field poles included in the entire iron core block is 4
And the relationship between the obtained m ₁ and m ₂ is m ₁ = 3
× m ₂ . Here, assuming that m ₂ = 1, m ₁ = 3. When the length of the interval piece 6 is obtained from the equation (1) using m ₁ = 3 at this time, L / 4 is obtained. Also, when the length of the interval piece 6 is obtained from the equation (2) using m ₂ = 1, the length is also L / 4. The phase difference of the induced voltage induced in the armature winding 5 by the first core block 1A and the second core block 1B is 180 °. for that reason,
The phase band indicating the arrangement of the armature windings 5 is as shown in FIG. In the linear motor having the phase band of the armature winding 5, the cogging thrust between the field poles of the iron core blocks 1A and 1B and the teeth 4a is as shown in FIG. Thrusts cancel each other. The cogging thrust due to the end effect is as shown in FIG. 6B, and the cogging thrusts cancel each other. Since the third embodiment is configured as described above, it is possible to eliminate the thrust fluctuation generated at the time of relative movement between the field pole and the armature 3 and the thrust fluctuation generated at the magnetic circuits formed at both ends of the iron core block. Cogging thrust between the teeth 4a and
This is an effective means for both the cogging thrust due to the end effect.
Although the first, second and third embodiments have been described, the present invention is not limited to the combination of the field poles and the teeth as described above, and the combination of the field poles and the teeth may be any combination. I do not care.

[0026]

As described above, according to the first to third embodiments of the present invention, the field core is divided into a plurality of core blocks, and the distance between the respective core blocks is increased. The spacing pieces are provided at intervals, so that the phases of the cogging thrust by the respective iron core blocks are shifted, and the cogging thrust of the entire field yoke can be reduced. Of these, the first embodiment is effective in reducing the cogging thrust between the field pole and the teeth, the second embodiment is effective in reducing the cogging thrust due to the end effect, and the third embodiment is effective. Is effective for reducing both the cogging thrust between the field pole and the teeth and the cogging thrust due to the end effect. In addition, by adopting a manufacturing method in which the field yoke is divided into blocks, when a cogging thrust that cannot be specified due to various dimensional errors or the like occurs in the manufacturing process, the length of the interval piece between the core blocks is appropriately adjusted. The cogging thrust can be easily reduced by adjusting.

[Brief description of the drawings]

FIG. 1 is a sectional view of a linear motor according to a first embodiment of the present invention.

FIGS. 2A and 2B show characteristics according to the first embodiment, wherein FIG. 2A shows a cogging thrust caused by field poles and teeth generated in each iron core block, and FIG. 2B shows a cogging thrust caused by an end effect generated in each iron core block. It is.

FIG. 3 is a sectional view of a linear motor according to a second embodiment of the present invention.

4A and 4B show characteristics according to the second embodiment, wherein FIG. 4A shows a cogging thrust caused by field poles and teeth generated in each iron core block, and FIG. 4B shows a cogging thrust caused by an end effect generated in each iron core block. It is.

FIG. 5 is a sectional view of a linear motor showing a third embodiment of the present invention.

FIG. 6A is a cogging thrust caused by field poles and teeth generated in each iron core block, and FIG. 6B is a cogging thrust caused by an end effect generated in each iron core block.

FIG. 7 is a sectional view of a conventional linear motor.

[Explanation of symbols]

 Reference Signs List 1A First iron core block (field iron core) 1B Second iron core block (field iron core) 1C Third iron core block (field iron core) 2 Permanent magnet 3 Armature 4 Armature iron core 4a Teeth 4b Yoke 4c Slot 5 Armature winding 6 Spacer

Claims (5)

[Claims] 1. A field iron core in which a plurality of permanent magnets constituting a field pole are alternately arranged in a line so as to alternately have different polarities, and are arranged so as to be opposed to the row of permanent magnets via a magnetic gap. An armature constituted by an armature core and an armature winding in which a coil is wound around a slot of the armature core; one of the field poles and the armature being a stator, and the other being a stator. In a linear motor in which the field pole and the armature run relatively as a mover, the field iron core is divided into a plurality of iron core blocks and arranged in a thrust direction, and a gap is provided between the iron core blocks. And a spacing piece of a magnetic material is inserted into a gap between the iron core blocks. 2. The number of divisions of the iron core block is n, the length of one iron core block is L, the number P of field poles included in the entire iron core block, and the number of teeth included in one iron core block. The least common multiple with S is LCM (P,
S), when a natural number not including a multiple of the number of divisions of the core block is represented by m ₁ , the length of the interval piece is The linear motor according to claim 1, wherein: 3. The number of divisions of the core block is n, the length of one core block is L, the number of field poles included in the entire core block is P, and a multiple of the division number of the core block is included. When no natural number is represented by m ₁ , the length of the interval piece is The linear motor according to claim 1, wherein: 4. The number of divisions of the core block is n, the length of one core block is L, the number P of field poles included in the entire core block, and the number of teeth included in one core block. a case showing the least common multiple of the S in LCM (P, S), using the coefficients m ₂ of claim 3, wherein the coefficient m ₁ according to claim 2, wherein the coefficient m ₁ and the coefficient m ₂ Is related to And the length of the spacing piece is expressed by the following equation using the coefficient m _1. The linear motor according to claim 1, wherein the linear motor is represented by the following equation: 5. The number of divisions of the core block is n, the length of one core block is L, the number of field poles included in the entire core block is P, and a multiple of the number of divisions of the core block is included. Where no natural number is represented by m ₁ , and using the coefficient m _{1 according} to claim ₂ and the coefficient m _{2 according} to claim 3, the relationship between the coefficient m ₁ and the coefficient m ₂ is expressed as 5] And the length of the spacing piece is given by the following equation using the coefficient m _2. The linear motor according to claim 1, wherein the linear motor is represented by the following equation: