JP2006304438A - Linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motor in which various problems caused by flux leakage can be solved by preventing flux leakage at the opposite ends of a stator. <P>SOLUTION: The linear motor comprises a stator arranged with a plurality of permanent magnets on the inside of a pair of yokes arranged oppositely, and a moving element with an armature winding portion arranged movably between the pair of yokes wherein flux leakage preventing portions are provided at the opposite ends of the pair of yokes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a linear motor, and more particularly to a device devised so that magnetic flux leakage from both ends of a pair of yokes constituting a stator can be prevented.

  A conventional linear motor has a configuration as shown in FIG. 6, for example. First, there is a stator 201, and this stator 201 is provided with a pair of yokes 203, 203 facing each other. The yokes 203 are connected via a yoke support member 205 installed in the lower part thereof. More specifically, the yoke 203 has a structure in which a plurality of yoke elements 203a are connected, and each yoke element 203a is fixed to the yoke support member 205 by a plurality of fixing screws (three in FIG. 6). ing.

  A plurality of permanent magnets 209 are installed at a predetermined pitch on the inner side surfaces of the pair of yokes 203, 203. In this case, the magnetic poles of the adjacent permanent magnets 209 and 209 are arranged so as to have different polarities, and the permanent magnets 209 and 209 facing each other are arranged so that the magnetic poles thereof have different polarities.

  A movable element 211 is disposed between the pair of yokes 203 of the stator 201 so as to be movable in the direction indicated by the arrow X in FIG. The mover 211 is composed of an upper plate 213 and a resin mold part 215 attached below the upper plate 213. As shown in FIG. 7, the resin mold part 215 includes a coil substrate 217 and a plurality of winding coil parts 219 installed on the coil substrate 217.

  In the above configuration, by supplying a predetermined current to the winding coil portion 219, thrust in the arrow X direction is generated in the mover 211, and thereby the mover 211 moves in the direction indicated by the arrow X. Become.

The conventional configuration has the following problems.
That is, when the both ends of the pair of yokes 203, 203 constituting the stator 201 are viewed, they are in an open state, and as a result, as shown in FIG. 8, magnetic flux leakage occurs at the open ends. As a result, there is a problem in that external devices such as a magnetic linear encoder are adversely affected.
In FIG. 8, the magnetic flux is indicated by a virtual line.
Further, there is a problem that an effective magnetic flux cannot be obtained at both ends where such magnetic flux leakage occurs, and a necessary thrust cannot be obtained. Therefore, conventionally, there has been a problem that the effective stroke has to be set shorter than the entire length of the stator 201.

  For example, Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6, Patent Literature 7, Patent Literature 8 and the like are disclosed as linear motors having the same type of configuration.

JP 2001-245464 A JP 2001-95224 A JP-T 09-511380 JP 2004-266914 A JP 2001-197718 A JP 2001-327152 A JP 05-184126 A JP 2004-187350 A

  The present invention has been made on the basis of the above points, and its object is to prevent a magnetic flux leakage at both ends of the stator and solve various problems caused by the magnetic flux leakage. Is to provide.

In order to solve the above problems, a linear motor according to a first aspect of the present invention includes a stator in which a plurality of permanent magnets are arranged inside a pair of opposing and arranged yokes, and a pair of yokes of the stator. And a mover having an armature winding portion movably disposed therebetween, wherein a magnetic flux leakage prevention portion for preventing magnetic flux leakage is provided at both ends of the pair of yokes. It is characterized by being.
A linear motor according to claim 2 is the linear motor according to claim 1,
The magnetic flux leakage prevention portion is a magnetic plate attached to both ends of the pair of yokes.
According to a third aspect of the present invention, there is provided the linear motor according to the second aspect, wherein the magnetic plate has a U-shaped cross section.

As described above, the linear motor according to the present invention is movable between a stator in which a plurality of permanent magnets are arranged inside a pair of opposing and arranged yokes and the pair of yokes of the stator. A linear motor comprising a mover having an armature winding portion disposed, and a magnetic flux leakage prevention portion for preventing magnetic flux leakage is provided at both ends of the pair of yokes. As a result, magnetic flux leakage at both ends of the stator can be prevented, the influence on the external device can be reduced, and the effective stroke length can be extended.
Further, the magnetic flux leakage prevention portion may be, for example, a magnetic plate attached to both ends of the pair of yokes.
Further, when the cross-sectional shape of the magnetic plate is U-shaped, it is convenient for securing a stroke.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First, as shown in FIG. 1, there is a stator 1, which is provided with a pair of yokes 3 and 3 facing each other. The yoke 3 has a structure in which a plurality of yoke elements 3a are connected, and is fixed to a base member (not shown).

  A plurality of permanent magnets 9 are installed at a predetermined pitch on the inner side surfaces of the pair of yokes 3 and 3. In this case, the magnetic poles of the adjacent permanent magnets 9 and 9 are arranged so as to have different polarities, and the opposing permanent magnets 9 and 9 are arranged so that the magnetic poles thereof have different polarities.

  A mover 11 is disposed between the pair of yokes 3 and 3 of the stator 1 so as to be movable in a direction indicated by an arrow X in FIG. The mover 11 includes an upper plate 13 and a resin mold portion 15 attached below the upper plate 13. As shown in FIG. 2, the resin mold portion 15 includes a coil substrate 17 and a plurality of winding coil portions 19 installed on the coil substrate 17.

Magnetic plates 21 and 21 as magnetic flux leakage prevention members are installed at both ends of the pair of yokes 3 and 3 of the stator 1 already described.
In the figure, only one of the magnetic plates 21 is shown.
By installing such magnetic plates 21, 21, magnetic flux leakage at both ends of the stator 1 is to be prevented.

The operation will be described based on the above configuration.
First, in a normal operation, when a predetermined current is supplied to the winding coil unit 19, a thrust in the direction indicated by the arrow X is generated in the mover 11, whereby the mover 11 is moved by the arrow X. It will move in the direction shown.
In addition, the magnetic flux at both ends of the stator 1 is as shown in FIG. 3. Since the magnetic plate 21 is installed as shown in FIG. 3, the magnetic plate 21 is not leaked to the outside. It will be in the closed state.
In FIG. 3, the magnetic flux is indicated by a virtual line.

As described above, according to the present embodiment, the following effects can be obtained.
First, magnetic flux leakage at both ends of the stator 1 can be effectively prevented. This will be described with reference to FIG. 4A shows the structure of a conventional linear motor stator 201, and FIG. 4B shows the configuration of the linear motor stator 1 of the present embodiment. In both of these structures, FIG. 4C shows the change in magnetic flux density outside the magnetic gap, and FIG. 4D shows the change in magnetic flux density in the magnetic gap.

First, looking at the situation outside the magnetic air gap, as shown in the diagram on the left side of FIG. 4C, in the conventional case, the magnetic flux density rapidly increases at the end of the stator 201. This means that magnetic flux leakage occurs in the magnetic gap at the end. On the other hand, as shown in the diagram on the right side of FIG. 4 (c), in the case of the present embodiment, the magnetic flux density does not increase even at the end, and this is the magnetic gap at the end. This means that there is no magnetic flux leakage.

On the other hand, looking at the situation inside the magnetic air gap, as shown in the diagram on the left side of FIG. 4D, in the conventional case, the magnetic flux density rapidly decreases at the end of the stator 201. . This means that magnetic flux leakage occurs in the magnetic gap at the end. On the other hand, as shown in the diagram on the right side of FIG. 4 (d), in the case of the present embodiment, the magnetic flux density does not decrease even at the end, and this is the magnetic gap at the end. This means that there is no magnetic flux leakage.

Thus, since the magnetic flux leakage at both ends of the stator 1 is effectively prevented, first, the influence of the magnetic flux on the external device, for example, the magnetic linear encoder can be reduced.
Further, it is possible to prevent a reduction in thrust at both end portions of the stator 1, thereby increasing the effective stroke length. This means that the apparatus can be miniaturized.
Moreover, since the cross-sectional shape of the magnetic material plate 21 is U-shaped, it is convenient for securing a stroke.

Next, a second embodiment of the present invention will be described with reference to FIG. In this case, the magnetic material plate 21 is formed in a flat plate shape, and other configurations are the same as those in the first embodiment.
Even with such a configuration, the same effect can be obtained.

The present invention is not limited to the first and second embodiments.
First, the shape of the magnetic material plate is not limited to the illustrated shape, and may be various shapes, for example, an arc shape.
It is also conceivable to provide the magnetic plate integrally with the yoke.
Moreover, the structure of the magnetic flux leakage prevention part of structures other than a magnetic material plate is also considered.
Further, the material of each component is not particularly limited.

The present invention relates to a linear motor, and particularly relates to a device devised so as to prevent magnetic flux leakage from both ends of a pair of yokes constituting a stator, and is suitable, for example, for a single-axis actuator.

It is a figure which shows the 1st Embodiment of this invention, and is a perspective view which shows the structure of a part of linear motor. It is a figure which shows the 1st Embodiment of this invention, and is II-II sectional drawing of FIG. It is a figure which shows the 1st Embodiment of this invention and is a top view of the linear motor for demonstrating an effect | action. 4A and 4B are diagrams showing a first embodiment of the present invention, in which FIG. 4A is a plan view showing the configuration of a conventional linear motor, and FIG. 4B is a plan view showing the configuration of the linear motor according to the embodiment; FIG. 4C is a characteristic diagram showing the change in magnetic flux density outside the magnetic gap between the embodiment and the conventional case, and FIG. 4D is the change in magnetic flux density in the magnetic gap. FIG. 5 is a characteristic diagram showing the comparison between the case of the embodiment and the case of the prior art. It is a figure which shows the 2nd Embodiment of this invention, and is a top view of the linear motor for demonstrating an effect | action. It is a figure which shows a prior art example, and is a perspective view which shows the structure of a part of linear motor. It is a figure which shows a prior art example, and is VII-VII sectional drawing of FIG. It is a figure which shows a prior art example, and is a top view of the linear motor for demonstrating magnetic flux leakage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stator 3 Yoke 3a Yoke element 9 Permanent magnet 11 Movable element 13 Upper plate 15 Resin mold 17 Coil board 19 Winding coil part 21 Magnetic body plate (Magnetic flux leakage prevention member)

Claims (3)

A stator having a plurality of permanent magnets arranged inside a pair of opposed and disposed yokes, and an armature winding portion movably disposed between the pair of yokes of the stator. In a linear motor comprising:
A linear motor characterized in that a magnetic flux leakage prevention portion for preventing magnetic flux leakage is provided at both ends of the pair of yokes. The linear motor according to claim 1,
The linear motor according to claim 1, wherein the magnetic flux leakage prevention part is a magnetic plate attached to both ends of the pair of yokes. The linear motor according to claim 2,
A linear motor characterized in that the magnetic plate has a U-shaped cross section.

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