JPH11308850A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor which significantly reduces cogging torque due to the effects of the permanent magnets at both ends of a needle and in which the speed ripple is small, even if the needle is lightened. SOLUTION: This linear motor of 3/8 in slots number for each pole and each phase, where three-phase armature winding 15 is applied to an armature and 8N-1 (n is a natural number) pieces of first permanent magnets 12, are arranged in a row in a magnetic field and two pieces of second permanent magnets 13 different in size from the first magnet 12 are arranged at both ends. In this case, linear motor that the width w' of a second permanent magnet 13 is, 0.5W<W'<0.6W, is realized, when the width of the first permanent magnet 12 is W. When the slot pitch is made τ, the distance λ' between the center of the second permanent magnet 13 and that of the first permenent magnet 12 on its inside can be made 0.9τ<λ'<1.0τ.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor for use in, for example, a semiconductor manufacturing apparatus or an FA machine, which dislikes cogging force, thrust ripple, and heat generation, and requires high speed, high acceleration / deceleration, or high precision positioning.

[0002]

2. Description of the Related Art A conventional linear motor is disclosed in US Pat. No. 4,633,108. This linear motor is composed of a mover in which a permanent magnet for a magnetic field is attached to a flat back yoke, and a stator in which a concentrated winding coil is wound around a tooth and a plurality of coils are arranged in the moving direction. . Further, when the pole pitch, which is the distance between adjacent permanent magnets, is λ, and the slot pitch, which is the distance between adjacent teeth, is τ, τ: λ
Has a 2: 3 relationship.

[0003]

However, the prior art has the following problems. That is, in the linear motor described in U.S. Pat. No. 4,633,108, a cogging force having a period of the slot pitch τ is generated when the mover moves due to the influence of the permanent magnets disposed at both ends of the mover. As a result, speed ripples occur, causing various problems during transport and processing. Further, according to the conventional configuration, when the pole pitch is λ and the slot pitch is τ,
Although τ: λ has a relationship of 2: 3, when this configuration is applied to a method of arranging permanent magnets at both ends of the mover when the number of slots for each pole and each phase can increase the winding coefficient, the cogging force is reduced. Instead, it became large and it was difficult to apply. Therefore, the problem to be solved by the present invention is:
It is an object of the present invention to provide a linear motor having a small speed ripple even when the weight of the mover is reduced by greatly reducing the cogging force due to the influence of the permanent magnets at both ends of the mover.

[0004]

In order to solve the above problems, a linear motor according to the present invention is provided with a three-phase armature winding on an armature and 8N-1 (N is a natural number) number of field motors. In a linear motor having 3/8 slots in each pole and each phase, one permanent magnet is arranged in a row, and two second permanent magnets having different sizes from the first permanent magnet are arranged at both ends. 1
When the width of the permanent magnet is W, the width W 'of the second permanent magnet is 0.5W <W'<0.6W. When the slot pitch is τ, the center distance λ ′ between the second permanent magnet and the first permanent magnet inside the second permanent magnet is 0.9τ <λ ′ <1.0τ. Further, the linear motor has M (M is a natural number)
Motor units, one of which is composed of two armature units, each of which is composed of two armature units each of which is connected to a split core having armature windings concentrated as armatures, and permanent magnets arranged in a line on a non-magnetic material frame. Permanent magnet unit 1 deployed
And two armature units sandwich one permanent magnet unit so as to form a constant left and right gap. With the above configuration, the cogging force generated by the influence of the permanent magnets at both ends of the mover can be reduced.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view as viewed from the front in claims 1 and 2, FIG. 2 is a cross-sectional view along AA 'in FIG. 1, and FIG. 3 is a diagram showing the shape of a permanent magnet and an armature.
In these figures, 1 is a mover, 2 is a first permanent magnet unit, 3 is a second permanent magnet unit, 4 is a linear guide, 5 is a stator, 6 is a stator frame, 7 is a mountain-shaped fixing member, 8 Is a first armature unit, 9 is a second armature unit, 10 is a third armature unit, 11 is a fourth armature unit, 12 is a first permanent magnet, 13 is a second permanent magnet, 14
Is a split core, and 15 is an armature winding. First, mover 1
Will be described. The mover 1 includes a linear guide 4 for supporting the movable member on both sides, and two permanent magnet units 2 and 3 for a field disposed perpendicular to the table surface. One magnet unit has two types of permanent magnets 1
A total of nine 2 and permanent magnets 13 are arranged in a line. First, the first permanent magnets 12 are located inside the mover 1 and are arranged at every pole pitch λ such that the polarities alternate. The second permanent magnets 13 are located at both ends of the mover 1 and are arranged to have a polarity opposite to the polarity of the first permanent magnets 12 adjacent thereto. Here, the relationship between the width W of the first permanent magnet 12 and the width W ′ of the second permanent magnet 13 is W: W ′ = 1: 0.54.

Next, the stator 5 will be described. The stator 5 includes four armature units 8 to 11 sandwiching the two magnet units 2 and 3 and the armature units 8 to 1
1 is affixed to the angled fixing member 7 and the linear guide 4
And a stator frame 6 receiving a mountain-shaped fixing member 7. One armature unit includes 18 split cores 14 and armature windings 15 preliminarily wound on the cores. Further, the surface of the armature winding 15 is stycast with a resin having good heat conductivity. In such a configuration, the relationship between the slot pitch τ and the pole pitch λ is τ: λ = 8: 9, and the distance from the center of the second permanent magnet 13 to the center of the first permanent magnet 12 adjacent thereto. The relationship with the distance λ ′ is τ: λ ′ = 1: 0.94. The distance L from the left end face of the second permanent magnet 13 to the left end face of the adjacent first permanent magnet 12 is L = λ ′ + (W−W ′) / 2 = 0.94 × τ + 0.23
× W. If W = 0.9 × τ, the slot pitch τ and the first permanent magnet 12
The relationship of the distance L from the left end surface of the second permanent magnet 13 to the left end surface of the second permanent magnet 13 is as follows: L = 0.94 × τ + 0.23 × 0.9 × τ = 1.15 ×
τ τ: L = 1: 1.15

With the above configuration, cogging force generated by the influence of the permanent magnets 12 and 13 at both ends of the mover 1 can be almost eliminated. Therefore, this effect will be described in comparison with a conventional example. According to the prior art, the relationship between the slot pitch τ and the distance L is τ: L = 2: 3 = 1: 1.5. When the magnet widths W and W 'and the slot pitch τ are the same as those of the present embodiment, the relationship between the slot pitch τ and the above-mentioned distance λ ′ is derived as follows: τ: λ ′ = 1: 1.29. That is, L and λ ′ are longer in the prior art than in the embodiment of the present invention. FIG. 4 shows the result of comparing the cogging force due to such a difference in structure. As can be seen from FIG. 4, the arrangement of the magnet according to the prior art is approximately 8 in the present invention.
Cogging force occurs at twice the amplitude. Further, the cogging force changes depending on the magnitude of λ ′ / τ, and λ ′ shown in the embodiment.
It becomes minimum when /τ=0.94. FIG. 5 shows the relationship between λ ′ / τ and the cogging force. The shape in which the cogging force is minimized depends on the ratio of the width W of the first permanent magnet 12 to the width W ′ of the second permanent magnet 13, but the condition is 0.9τ <λ ′ <1.0τ. ... (1) and 0.5 W <W ′ <0.6 W (2) If the expression (2) is satisfied, the cogging force can be made relatively small. That is,
Compared with the case where W = W ', the cogging force can be reduced to about 1/3 by employing only the expression (2), and by satisfying the condition of the expression (1), the present invention The cogging force can be reduced to about ８ of that of the technology.

[0008]

As described above, according to the configuration of the present invention, the cogging force due to the influence of the permanent magnets at both ends of the mover can be greatly reduced. In addition, not only the amplitude of the cogging force but also the order of generation of the cogging force are increased, and a linear motor having a small speed ripple can be realized even if the mover is reduced in weight.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the embodiment of the present invention as viewed from above.

FIG. 3 is a diagram showing a shape of an embodiment of the present invention.

FIG. 4 is a diagram showing cogging force waveforms according to the present invention and the prior art.

FIG. 5 is a diagram showing a relationship between a permanent magnet shape and a cogging force amplitude value according to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 mover, 2 first permanent magnet unit, 3 second permanent magnet unit, 4 linear guide, 5 stator, 6 stator frame, 7 angled fixing member, 8 first armature unit, 9 second armature unit , 10 third armature unit, 11 fourth armature unit, 12 first permanent magnet, 13 second permanent magnet, 14 split core, 15 armature winding

Claims (3)

[Claims] A three-phase armature winding is applied to an armature, and 8N-1 (N is a natural number) first permanent magnets are arranged in a line in a field, and the first permanent magnets are provided at both ends thereof. Is the number of slots in each pole and each phase where two second permanent magnets having different sizes are provided.
/ 8, wherein the width of the first permanent magnet is W, and the width W 'of the second permanent magnet is 0.5W <W'<0.6W. 2. When the slot pitch is τ, a center distance λ ′ between the second permanent magnet and the first permanent magnet inside the second permanent magnet is defined as λ ′.
2. The linear motor according to claim 1, wherein 0.9τ <λ ′ <1.0τ. 3. The linear motor is composed of M (M is a natural number) motor units, and one of the motor units is an electric motor in which a split core in which armature windings are concentrated and wound as an armature is connected. A permanent magnet unit in which permanent magnets are arranged in a line on a non-magnetic material frame, and two armature units sandwich the one permanent magnet unit so as to form a constant left and right gap. The linear motor according to claim 1, wherein: