JP2003209963A - Linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motor with high accuracy capable of minimizing the occurrence of thrust fluctuation without the risk of deteriorating magnetic field efficiency caused by the influence of end effects at both ends of a york. <P>SOLUTION: In a linear motor equipped with a field magnet pole 2 having a Halbach array structure provided on a york 1 and an armature 4 having an armature winding 3 disposed opposed to the field magnet pole 2 through a magnetic space, the width Wc in the advancing direction of a first main magnetic pole 2C disposed at each of both ends of the york 1 is made narrower than the width Wa in the advancing direction of a second main magnetic pole 2A disposed at each position other than both the ends of the york 1. The width Wd in the advancing direction of the first sub-magnetic pole 2D disposed adjacent to the first main magnetic pole 2C is made wider than the width Wb in the advancing direction of the second sub-magnetic pole 2D disposed opposed to the first sub-magnetic pole 2D of the second main magnetic pole 2A. When taking the distance between centers of the second main magnetic poles 2A as a pole pitch P and the distance between centers of the first main magnetic pole 2C and second main magnetic poles 2A as P', the relation between P an P' is shown as P'=1.03×P. <P>COPYRIGHT: (C)2003,JPO

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 FA equipment such as semiconductor manufacturing equipment and machine tools, and particularly having a field pole having a Halbach array structure.

[0002]

2. Description of the Related Art Conventionally, in FA equipment such as semiconductor manufacturing equipment or machine tools, a permanent magnet forming a field pole and a magnetic pole surface of the permanent magnet are provided so as to achieve high-speed and high-accuracy feeding and machining. The use of linear motors with armatures in which the armature windings are arranged facing each other with a magnetic gap in between is being sought. FIG. 3 is a plan sectional view of a conventional linear motor. In FIG. 3, reference numeral 1 denotes a yoke, which is made up of a pair of two parallel ferromagnetic materials. Reference numeral 2 denotes a field pole, which has a Halbach array structure composed of permanent magnets that are adjacent to each other along the traveling direction on the yoke 1 and that are composed of a main magnetic pole 2E and an auxiliary magnetic pole 2F having different magnetic pole directions. Reference numeral 3 denotes an armature winding arranged so as to face the field pole 2 with a magnetic gap therebetween, and 4 denotes an armature provided with the armature winding 3, which is movable relative to the longitudinal direction of the field pole 2. To do. Here, in the field pole 2, the sub pole 2
The ratio of the width in the traveling direction of F to the width in the traveling direction of the main magnetic pole 2E is
It is set to 0.75 to 0.8. In such a configuration, the linear motor moves the field pole 2 linearly by using the armature 4 as a stator and the field pole 2 as a mover that relatively moves.

[0003]

However, in the prior art, the main magnetic pole 2E and the auxiliary magnetic pole 2 located at the center of the yoke 1 are used.
The dimensional ratio of the magnet width of F and the main pole 2 located at the end of the yoke 1
Since the dimensional ratio of the magnet widths of E and the auxiliary magnetic pole 2F is the same, the magnetic path at both ends of the yoke 1 is different from the central part of the yoke 1 due to the end effect, and the magnetic field efficiency deteriorates. There was a problem that fluctuations occurred. As a result, control performance has deteriorated in machine tools and semiconductor devices incorporating a linear motor. The present invention has been made to solve the above problems, and a highly accurate linear motor capable of reducing the occurrence of thrust fluctuations as much as possible without deteriorating the magnetic field efficiency due to the effect of the end effect at both ends of the yoke. The purpose is to provide.

[0004]

In order to solve the above-mentioned problems, the present invention according to claim 1 provides a pair of two yokes made of ferromagnetic materials parallel to each other and a moving direction on the yoke. An electric machine having a field pole having a Halbach array structure composed of a main pole and a sub pole having different magnetic pole directions, and an armature winding arranged to face the field pole via a magnetic gap. A linear motor having a child and a movable element that relatively moves one of the field pole and the armature, and the other as a stator, wherein the main magnetic pole is disposed at both ends of the yoke. The width Wc of the first main magnetic pole in the traveling direction is formed to be narrower than the width Wa of the second main magnetic pole provided at the inner position except both ends of the yoke in the traveling direction. 1st sub-magnet arranged next to 1 main pole Width Wd of the traveling direction of the second
It is formed so as to be wider than the width Wb in the traveling direction of the second auxiliary magnetic pole arranged on the side opposite to the first auxiliary magnetic pole of the main magnetic pole, and the distance between the centers of the second main magnetic poles is a pole pitch P, When the distance between the centers of the first main magnetic pole and the second main magnetic pole is P ′, there is a relation of P ′ = 1.03 × P. According to a second aspect of the present invention, in the linear motor according to the first aspect, when the number of poles of the main magnetic pole is an even number, the first
The width of the main magnetic pole in the advancing direction is 0.45 to 0.55 of the width of the second main magnetic pole in the advancing direction. According to a third aspect of the present invention, in the linear motor according to the first aspect, when the number of poles of the main magnetic pole is an odd number, the width of the first main magnetic pole in the traveling direction is set to the width of the second main magnetic pole in the traveling direction. 0.75 to 0.
It is set to 85.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan sectional view of a linear motor showing an embodiment of the present invention. It should be noted that description of the components of the present invention that are the same as those of the prior art will be omitted, and only different points will be described. In the figure, 2C is a first main magnetic pole, 2D is a first auxiliary magnetic pole, 2A is a second main magnetic pole, and 2B is a second auxiliary magnetic pole. The features of the present invention are as follows. That is, in one main magnetic pole forming the field pole, the width Wc of the first main magnetic pole 2C arranged at both ends of the yoke 1 in the traveling direction is the second main magnetic pole 2A provided at a position excluding both ends of the yoke 1. The width Wd of the second auxiliary magnetic pole 2A is smaller than the width Wa of the auxiliary auxiliary magnetic pole 2D in the moving direction of the first auxiliary magnetic pole 2D arranged adjacent to the first main magnetic pole 2C. Is formed so as to be wider than the width Wb in the traveling direction of the second auxiliary magnetic pole 2B arranged on the side opposite to the first auxiliary magnetic pole 2D, and the distance between the centers of the second main magnetic poles 2A is the pole pitch P, When the distance between the centers of the first main magnetic pole 2C and the second main magnetic pole 2A is P ′, the relationship is P ′ = 1.03 × P.

Next, the magnetic field analysis result of the linear motor according to this embodiment by the finite element method will be described. FIG. 2 is a schematic diagram showing the magnetic flux distribution of the linear motor in this embodiment. In the figure, for convenience, the model is cut in half with respect to the axis along the traveling direction of the linear motor.
Compared with the conventional one, the width Wc of the first main magnetic pole 2C is set to the second main magnetic pole 2C.
The width Wd of the first auxiliary magnetic pole 2D is made narrower than the width Wa of A, and the width Wd of the first auxiliary magnetic pole 2D is made wider than the width Wb of the second auxiliary magnetic pole 2B, and the distance between the centers of the first main magnetic pole 2C and the second main magnetic pole 2A is expressed by the above formula. With such a limitation, as shown in FIG. 2, the flow of the magnetic flux becomes substantially the same at both ends of the yoke 1 and the center position in the traveling direction of the yoke 1, so that there is no thrust fluctuation in the stroke of the linear motor.

Therefore, in this embodiment, the width Wc in the traveling direction of the first main magnetic poles 2C disposed at both end positions of the yoke 1 as one main magnetic pole constituting the field magnetic pole is at a position excluding both ends of the yoke 1. Width Wa of the second main magnetic pole 2A provided in
The width Wd in the traveling direction of the first auxiliary magnetic pole 2D, which is formed so as to be narrower and is arranged next to the first main magnetic pole 2C as the other auxiliary magnetic pole, has the first auxiliary magnetic pole 2D of the second main magnetic pole 2A. Is formed to be wider than the width Wb in the traveling direction of the second auxiliary magnetic pole 2B disposed on the opposite side to the second main magnetic pole 2
The pole pitch P is the distance between the centers of the two comrades, and the first main pole 2
When the distance between C and the center of the second main magnetic pole 2A is P ′,
Since the structure having the relation of P ′ = 1.03 × P is provided, the flow of magnetic flux at both ends of the yoke and the flow of magnetic flux at the center of the yoke become substantially uniform, and due to the influence of the end effect at both ends of the yoke 1. It is possible to provide a movable and highly accurate linear motor that can minimize the occurrence of thrust fluctuations without deteriorating the magnetic field efficiency. Since the fluctuation of the thrust of the linear motor can be suppressed, the controllability can be improved in a machine tool or a semiconductor device in which the linear motor is incorporated.

In the above embodiment, the optimum widths of the main magnetic pole and the auxiliary magnetic pole were examined by analysis and experiments in order to suppress the thrust fluctuation of the linear motor. For example, in addition to the conditions shown in the above embodiment, when the number of poles of the main magnetic pole is an even number, the width of the first main magnetic pole 2C in the traveling direction is set to the second main magnetic pole 2A.
It was confirmed that when the width in the traveling direction is set to 0.45 to 0.55, the thrust variation of the linear motor can be reduced by 15% to 20% compared to the conventional case. When the number of main magnetic poles is an odd number, the width of the first main magnetic pole 2C in the traveling direction is set to the second main magnetic pole 2A.
It was confirmed that when the width in the traveling direction is set to 0.75 to 0.85, the thrust variation of the linear motor can be reduced by 120% to 30% compared to the conventional case. As a result, it is possible to further suppress the thrust force variation of the linear motor.

[0009]

As described above, according to the present invention, the width Wc in the traveling direction of the first main magnetic poles arranged at both ends of the yoke as one main magnetic pole constituting the field magnetic pole is equal to that of the yoke. Width Wa in the traveling direction of the second main pole provided at a position excluding both ends
The width Wd in the traveling direction of the first auxiliary magnetic pole, which is formed so as to be narrower and is arranged next to the first main magnetic pole as the other auxiliary magnetic pole, is on the side opposite to the first auxiliary magnetic pole of the second main magnetic pole. It is formed so as to be wider than the width Wb of the arranged second auxiliary pole in the traveling direction, and the distance between the centers of the second main poles is the pole pitch P, and the distance between the centers of the first main pole and the second main pole is When the distance is P ′, the structure is such that P ′ = 1.03 × P, so that the flow of magnetic flux at both ends of the yoke and the flow of magnetic flux at the center of the yoke are substantially uniform, and both ends of the yoke are It is possible to provide a movable and highly accurate linear motor capable of reducing the occurrence of thrust fluctuations as much as possible without deteriorating the magnetic field efficiency due to the influence of the end effect in FIG.
Since the fluctuation of the thrust of the linear motor can be suppressed, the controllability can be improved in a machine tool or a semiconductor device in which the linear motor is incorporated.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a linear motor showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a magnetic flux distribution of a linear motor in this embodiment.

FIG. 3 is a plan sectional view of a linear motor showing a conventional technique.

[Explanation of symbols]

1 York 2 field magnetic pole 2A Second main pole 2B Second auxiliary magnetic pole 2C 1st main pole 2D first auxiliary pole 3 armature winding 4 armature

Claims (3)

[Claims] 1. A pair of two yokes (1) made of ferromagnetic materials parallel to each other, and a main magnetic pole and a sub magnetic pole having different magnetic poles along the traveling direction on the yoke (1). Field pole having Halbach array structure composed of (2)
And an armature (4) having an armature winding (3) arranged to face the field pole (2) via a magnetic gap, the field pole (2) and the armature ( 4) In a linear motor in which one of the two is relative to a mover and the other is a stator, the main magnetic poles of the first main magnetic pole (2C) arranged at both ends of the yoke (1). A width Wc in the traveling direction is provided at a position inside the yoke (1) excluding both ends of the yoke (1).
A) is formed so as to be narrower than the width Wa in the traveling direction of A), and the auxiliary magnetic pole has a width Wd in the traveling direction of the first auxiliary magnetic pole (2D) arranged adjacent to the first main magnetic pole (2C). The second main magnetic pole (2A) is formed to be wider than the width Wb of the second auxiliary magnetic pole (2B) arranged on the side opposite to the first auxiliary magnetic pole (2D) in the traveling direction. The pole pitch P is the distance between the centers of the magnetic poles (2A), and the first main magnetic pole (2C) and the second main magnetic pole (2).
When the distance between the centers of A) is P ′, P ′ = 1.03
A linear motor having a relationship of × P. 2. When the number of poles of the main magnetic pole is an even number, the width of the first main magnetic pole (2C) in the traveling direction is 0.45 to the width of the second main magnetic pole (2A) in the traveling direction. The linear motor according to claim 1, wherein the linear motor is 0.55. 3. When the number of poles of the main magnetic pole is an odd number, the width of the first main magnetic pole (2C) in the traveling direction is set to the second main magnetic pole (2).
2. The linear motor according to claim 1, wherein the width in the traveling direction of A) is 0.75 to 0.85.