WO2018174235A1 - Linear motor - Google Patents

Abstract

The purpose of the invention is to provide a linear motor such that it is possible to significantly reduce attractive force while achieving a compact configuration and high thrust generation. The linear motor is provided with: a mover having a magnet array comprising an arrangement of a plurality of rectangular permanent magnets; a back yoke disposed so as to face the mover with a gap therebetween and serving as a stator; and an armature disposed on the opposite side from the back yoke so as to face the mover with a gap therebetween and serving as the stator. The magnetization direction of each of the plurality of permanent magnets is in a thickness direction thereof, and the magnetization directions of adjoining permanent magnets are in opposite directions. The armature has a plurality of magnetic pole teeth, each having a drive coil wound thereon, at an equal pitch, and the back yoke has a plurality of magnetic pole teeth arranged on a surface facing the mover at the same positions as the magnetic pole teeth of the armature in a movable direction of the mover.

Description

Linear motor

The present invention relates to a linear motor that extracts a linear motion output by combining a mover and a stator.

Conventionally, a method of converting the output of a rotary motor into linear motion using a ball screw has been used for X and Y movement, but since the moving speed is slow, a linear motor that can directly extract linear motion output can be used. Use is in progress. The linear motor is generally configured by combining a mover having a plurality of rectangular permanent magnets and an armature having a plurality of magnetic pole teeth.

Also, since a wire bonder and a chip mounter in a processing machine of a semiconductor manufacturing apparatus require a high-speed repetitive motion, it is preferable to use a linear motor that can obtain a large acceleration with a small mass. In order to reduce the size of such a linear motor, for example, as disclosed in Patent Document 1 or 2, the permanent magnet of the mover is not opposed to the entire surface of the armature as the stator, but is movable. A linear motor having a configuration in which the arrangement length of permanent magnets in the child is shorter than the length of the armature is employed.

This type of linear motor includes a mover having a magnet array in which a plurality of permanent magnets are arrayed and a flat plate-shaped back yoke integrated with the magnet array, and an armature having a drive coil in each of a plurality of magnetic pole teeth. Is configured to face each other with a gap. When the drive coil is energized, the mover (magnet arrangement and back yoke) moves, and the difference in length between the mover and the armature becomes the operable stroke of the linear motor.

When the mover is composed of a back yoke formed of a ferromagnetic material and a magnet arrangement, an attractive force is generated between the opposing stator. Due to the generated suction force, a large vertical drag acts on the bearing that supports the mover so as to be movable in a predetermined direction. This normal drag brings about a shortened life of the bearing. Further, the direction in which the normal force acts is a direction that intersects the movable direction of the mover. Therefore, it is necessary to select a bearing in consideration of the normal drag. Therefore, a larger bearing is selected than a bearing that conforms to the load of the mover. This leads to an increase in the size of the entire linear motor.

Therefore, unlike the linear motor described above, linear motors have been proposed in which only the magnet arrangement functions as a mover and the back yoke functions as a stator (Patent Documents 3 to 5, etc.).

In this type of linear motor, the magnet arrangement and the flat back yoke are separated, a gap is formed on the opposite side of the armature, the back yoke is opposed to the magnet arrangement, and only the magnet arrangement can be moved. Only the magnet array moves, and the back yoke does not move like the armature. The length of the magnet array is shorter than the length of the armature, and the difference in length is the stroke at which the linear motor can operate.

JP 2005-269822 A Republished patent WO2016 / 159034 JP 2005-117856 A JP2015-130754A JP 2005-184984 A

The mover is strongly attracted to the magnetic pole tooth surfaces of the opposing armature. The suction force F at this time is expressed by the following formula.
F = B ² S / 2μ ₀
(Where B: magnetic flux density on the magnetic pole teeth of the electrode, S: effective area facing the mover and armature, μ ₀ : permeability of vacuum)

In a linear motor having a mover in which a magnet array and a flat back yoke are integrated (integrated linear motor: Patent Document 1 or 2, etc.), this attractive force is usually several times to ten times or more than the rated thrust. It becomes. Therefore, there is a problem that the mover is bent by a large suction force. As a result, the dimensional accuracy of a processing machine using a linear motor in which such bending occurs is deteriorated. Further, it is necessary to increase the rigidity of the mover, and there is a problem that the configuration is increased in size.

Since excessive suction force is also applied to the linear guide that supports the mover, the linear guide needs to have a large rated load so that it can withstand this excessive suction force. I can't. Therefore, it is desirable to reduce the above suction force. However, when reducing the suction force, it is necessary to realize both a small configuration and generation of a large thrust.

Also, in the integrated linear motor, there is a problem that the cogging torque is increased due to a large edge effect and the detent force is large.

In a linear motor configured to move only the magnet array by separating the magnet array and the flat back yoke (separated linear motor: Patent Documents 3 to 5, etc.), the back yoke and the armature are included in the magnet array. Therefore, the entire suction force is smaller than that of the integrated linear motor. However, in the separation type linear motor, the magnetic pole area facing the magnet arrangement is only the area of the opposing magnetic pole teeth on the armature side, whereas it is almost the same as the area of all the magnets on the back yoke side. Therefore, when the magnetic flux density in both gaps is the same, a larger attractive force acts on the back yoke side according to the ratio of the magnetic pole area, so that the overall attractive force is greatly reduced. Can't hope.

Therefore, the gap between the magnet array and the back yoke is widened to reduce the magnetic flux density of the gap, and the attractive force between the magnet array and the back yoke is reduced to the same extent as the attractive force between the magnet array and the armature. It is possible. However, when the gap between the magnet array and the back yoke is widened, the magnetic flux density for generating the thrust from the armature also decreases, and there is a problem that the thrust becomes small. Therefore, in the separation type linear motors proposed so far, there is a problem that a reduction in thrust is inevitable in order to reduce the attractive force acting on the mover.

In the separate linear motor, as described above, the attractive force between the mover (magnet arrangement) and the stator (armature) and the attractive force between the mover and the back yoke have substantially the same magnitude. Since the directions are opposite, the suction force acting on the mover can be reduced. However, it has been clarified that the eddy current generated in the back yoke during operation is increased by separating the back yoke and the magnet arrangement. An increase in eddy current leads to heat generation. Such a linear motor is not suitable for a stage drive source in an apparatus that needs to keep the environmental temperature within a predetermined range, for example, a semiconductor manufacturing apparatus.

The present invention has been made in view of such circumstances, and provides a linear motor that can greatly reduce the suction force and reduce the detent force while achieving a compact configuration and generation of a large thrust. The purpose is to do.

Another object of the present invention is to provide a linear motor capable of suppressing eddy currents while reducing the attractive force acting on the magnet arrangement.

A linear motor according to the present invention includes a mover having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator that is opposed to the mover with a gap, and the mover An armature as a stator disposed opposite to the back yoke with a gap therebetween, and the magnetization direction of each of the plurality of permanent magnets is a thickness direction, and adjacent permanent magnets The magnetizing direction is reverse, the armature has a plurality of magnetic pole teeth each having a drive coil wound at an equal pitch, and the back yoke is arranged on the surface facing the mover. There are a plurality of magnetic pole teeth at the same position in the moving direction of the armature and the magnetic pole teeth of the armature, and the magnetic pole area of the magnetic pole teeth in the back yoke is 0 of the magnetic pole area of the magnetic pole teeth in the armature. .9 times to 1.1 times , The gap between the mover and the back yoke, and wherein the movable element and be equal to the gap or greater with the armature.

In the linear motor according to the present invention, a mover having a magnet arrangement in which a plurality of permanent magnets are arranged, a back yoke disposed opposite to the mover with a gap, and a gap on the opposite side of the back yoke. An armature disposed opposite to the mover. The magnet arrangement functions as a mover, and the back yoke and armature function as a stator. Each of the plurality of rectangular permanent magnets in the magnet array is magnetized in the thickness direction, and the magnetization directions are opposite between adjacent permanent magnets. The armature has a plurality of magnetic pole teeth at an equal pitch, and a drive coil is wound on each magnetic pole tooth. In the back yoke, the surface facing the mover is not flat, and a plurality of magnetic pole teeth are formed at an equal pitch. The pitch of the magnetic pole teeth in the back yoke is equal to the pitch of the magnetic pole teeth of the armature, and the position of the magnetic pole teeth in the back yoke is the same position as the magnetic pole teeth of the armature in the moving direction of the mover (linear motor). The magnetic pole area of the magnetic pole teeth of the back yoke is 0.9 to 1.1 times the magnetic pole area of the magnetic pole teeth of the armature. Further, the gap between the mover and the back yoke is not less than the gap between the mover and the armature.

In the linear motor of the present invention, the back yoke is provided with magnetic pole teeth having substantially the same magnetic pole area at the same position as the armature. That is, only the back yoke portion to which the drive magnetic flux from the armature is applied is brought close to the mover, and the gap from the mover is opened except for the portion facing the magnetic pole teeth of the armature. Since the magnetic pole area of the armature facing the mover and the magnetic pole area of the back yoke facing the mover are substantially equal, they are effectively canceled out and the overall attractive force is greatly reduced. Therefore, the suction force can be significantly reduced without increasing the gap between the mover and the back yoke. At this time, since it is not necessary to increase the gap between the mover and the back yoke, the reduction in thrust is small.

Also, since the shear region of the driving magnetic flux is generated in the back yoke due to the uneven shape due to the formation of the magnetic pole teeth on the back yoke, not only the armature but also the back yoke contributes to the generation of thrust. This thrust generation compensates for a decrease in thrust due to the increase in the gap (air gap) with the mover at two places, and a large thrust as a whole can be obtained. Therefore, the attractive force acting on the magnet arrangement (mover) can be greatly reduced while maintaining a large thrust.

In the linear motor of the present invention, a mover is provided between an armature having a plurality of magnetic pole teeth at an equal pitch and a back yoke having a plurality of magnetic pole teeth in the same position as the armature magnetic pole teeth. Since the cogging of the magnet arrangement in the direction perpendicular to the movable direction is reduced, the detent force of the mover can be reduced.

When the magnetic pole area of the back yoke magnetic pole teeth is made too large, a large amount of magnetic flux is picked up from around to increase the attractive force. On the other hand, when the magnetic pole area of the magnetic pole teeth of the back yoke is made too small, thrust is obtained For this reason, the magnetic flux is reduced and the thrust is reduced. Therefore, the magnetic pole area of the magnetic pole teeth of the back yoke is set to 0.9 to 1.1 times the magnetic pole area of the magnetic pole teeth of the armature.

Since the drive coil is wound on the armature magnetic pole teeth, the armature magnetic pole teeth are not so low, and the height of the armature magnetic pole teeth is higher than the height of the magnetic pole teeth in the back yoke. For this reason, since the height of the magnetic pole teeth is low in the back yoke, a magnetic flux is also generated in a portion other than the magnetic pole teeth, and the attractive force tends to be larger than that of the armature side. Therefore, the gap between the mover and the back yoke is made equal to or larger than the gap between the mover and the armature so that the suction force can be efficiently canceled.

The linear motor according to the present invention is characterized in that the height of the magnetic pole teeth in the back yoke is not less than 1/20 times and not more than twice the pitch of the magnetic pole teeth.

In the linear motor of the present invention, when the height of the magnetic pole teeth of the back yoke is made too small compared to the pitch, the effect of providing the magnetic pole teeth (uneven shape) cannot be obtained. If the height is made too large compared to the pitch, the effect does not change and the size goes down. Therefore, the height of the magnetic pole teeth in the back yoke is set to 1/20 times or more and 2 times or less of the pitch of the magnetic pole teeth.

The linear motor according to the present invention is characterized in that the length of the mover is shorter than the length of the armature and shorter than the length of the back yoke.

In the linear motor of the present invention, the length of the mover is shorter than the length of each of the armature and the back yoke. Therefore, it is a small configuration and a large acceleration can be secured. Further, since the edge effect is reduced, the cogging torque is reduced and the detent force can be reduced.

The linear motor according to the present invention is characterized in that the size of the gap between the mover and the back yoke and / or the size of the gap between the mover and the armature is variable.

In the linear motor of the present invention, the size of the gap between the mover and the back yoke and / or the size of the gap between the mover and the armature is variable. Therefore, by adjusting the size of the gap between the mover and the back yoke and / or the size of the gap between the mover and the armature according to the magnitude of the driving magnetomotive force at the time of use, the attraction force is almost zero. It is possible to

A linear motor according to the present invention includes a mover having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator that is opposed to the mover with a gap, and the mover An armature as a stator disposed opposite to the back yoke with a gap therebetween, and the magnetization direction of each of the plurality of permanent magnets is a thickness direction, and adjacent permanent magnets The magnetizing direction is reverse, the armature has a plurality of magnetic pole teeth each having a drive coil wound at an equal pitch, and the back yoke is arranged on the surface facing the mover. The armature has a plurality of magnetic pole teeth at the same position in the moving direction of the armature and the magnetic teeth of the armature, and the magnetic pole teeth of the back yoke have a plurality of plate-like members in the moving direction of the mover. Laminated in the direction that intersects And wherein the door.

In the linear motor of the present invention, it is possible to reduce the eddy current while reducing the attractive force acting on the mover by making the magnetic pole teeth have a laminated structure.

In the linear motor according to the present invention, the back yoke has a plurality of plate-like members stacked in the stacking direction of the magnetic pole teeth. Thus, the plate member constituting the laminated portion of the back yoke and the plate member constituting the magnetic pole teeth are integrated.

In the linear motor according to the present invention, the back yoke can further reduce the eddy current by forming a part of the thickness direction from the connecting portion with the magnetic pole teeth in a laminated structure. Further, since the plate-like member constituting the laminated portion of the back yoke and the plate-like member constituting the magnetic pole teeth are integrated, the number of manufacturing steps can be reduced.

The linear motor according to the present invention is characterized in that the plurality of plate-like members are subjected to insulation treatment on the laminated surface.

In the linear motor of the present invention, since the plurality of plate-like members are subjected to insulation treatment on the laminated surface, the eddy current can be further reduced.

In the linear motor according to the present invention, the mover has a holding member for holding the magnet arrangement, and the holding member has a plurality of holes into which the plurality of permanent magnets are inserted. It is characterized by that.

In the linear motor of the present invention, the magnet arrangement (a plurality of permanent magnets) is held by the holding member. Therefore, since the rigidity of the mover (magnet arrangement) is increased, the detent force can be reduced because deformation such as bending and bending of the permanent magnet hardly occurs.

The linear motor according to the present invention is characterized in that the mover has a plate-like base material to which the holding member and the plurality of permanent magnets are bonded and fixed.

In the linear motor of the present invention, the magnet array (plural permanent magnets) and the holding member are bonded and fixed to the plate-like base material in a state where the plural permanent magnets are inserted into the holes of the holding member. Therefore, the rigidity of the mover (magnet arrangement) can be further increased to further reduce the detent force, and the permanent magnet can be prevented from falling off.

In the linear motor of the present invention, the attractive force acting on the mover (magnet arrangement) can be greatly reduced and the detent force of the mover can be reduced while realizing a small configuration and generation of a large thrust. Can do. Therefore, the deformation | transformation by the bending accompanying a big attraction force can be suppressed, and the deterioration of the dimensional accuracy of the apparatus in which a linear motor is utilized can be prevented. Since the suction force can be reduced, the rigidity of the mover and the support system that supports the mover can be reduced, and not only can the size be reduced, but also the acceleration can be improved by reducing the weight of the movable mass. In addition, by providing a magnetic pole tooth structure on the back yoke, thrust from the back yoke is added to the mover, so that a reduction in thrust due to the provision of a gap between the magnet array and the back yoke is minimized. be able to.

In the linear motor of the present invention, it is possible to suppress eddy currents while reducing the attractive force acting on the mover (magnet arrangement).

1 is a perspective view illustrating a configuration of a linear motor according to a first embodiment. 1 is a side view showing a configuration of a linear motor according to a first embodiment. FIG. 3 is a plan view illustrating a configuration of a mover in the linear motor according to the first embodiment. FIG. 3 is an exploded perspective view illustrating a configuration of a mover in the linear motor according to the first embodiment. FIG. 3 is a side view showing the flow of magnetic flux in the linear motor according to the first embodiment. FIG. 3 is a diagram illustrating a side shape of a back yoke in the linear motor according to the first embodiment. 3 is a plan view showing an armature material used for manufacturing an armature in the linear motor according to Embodiment 1. FIG. FIG. 3 is a diagram showing armature windings in the linear motor of the first embodiment. FIG. 3 is a top view illustrating a configuration of the linear motor according to the first embodiment. 1 is a side view showing a configuration of a linear motor according to a first embodiment. 4 is a graph showing a variation in thrust with respect to an electrical angle of a linear motor as an example of the first embodiment. 3 is a graph showing thrust characteristics of an example linear motor according to the first embodiment. 3 is a graph showing the attractive force characteristics of a linear motor as an example of Embodiment 1; It is a side view which shows the structure of the linear motor of the 1st prior art example (structure which integrated the magnet arrangement | sequence and the back yoke into the needle | mover). It is a top view which shows the structure of the linear motor of a 1st prior art example. It is a side view which shows the structure of the linear motor of a 1st prior art example. It is a side view which shows the structure of the linear motor of the 2nd prior art example (structure which used only the magnet arrangement | sequence as a needle | mover and used the flat back yoke as a stator). It is a top view which shows the structure of the linear motor of a 2nd prior art example. It is a side view which shows the structure of the linear motor of a 2nd prior art example. It is a graph which shows the average thrust in the linear motor of a 1st prior art example, a 2nd prior art example, and an example of Embodiment 1. FIG. 6 is a graph showing average suction force in the linear motor of the first conventional example, the second conventional example, and an example of the first embodiment. 5 is a graph showing thrust characteristics of a linear motor of another example of the first embodiment. 6 is a graph showing the attractive force characteristics of a linear motor of another example of the first embodiment. 6 is a graph showing thrust characteristics of a linear motor of still another example of the first embodiment. 6 is a graph showing the attractive force characteristics of a linear motor of still another example of the first embodiment. FIG. 6 is a perspective view illustrating a configuration example of a linear motor according to a second embodiment. FIG. 6 is a side view illustrating a configuration example of a linear motor according to a second embodiment. It is a perspective view which shows the structural example of the magnetic pole tooth contained in a back yoke. It is a fragmentary perspective view which shows the structural example of the base board contained in a back yoke. It is a partial perspective view of a back yoke. It is a partial side view of a linear motor. It is a graph which shows the Joule loss of the linear motor by related technology. 6 is a graph showing Joule loss of a linear motor in a basic example of the second embodiment. It is a side view which shows the other structural example of a back yoke. It is a perspective view which shows the structural example of a magnetic pole tooth block. It is a perspective view which shows the structural example of a base part. It is a partial side view of a linear motor. 6 is a graph showing Joule loss of a linear motor in a basic example of the second embodiment. 6 is a graph showing Joule loss of a linear motor in a first modification of the second embodiment. It is a side view which shows the other structural example of a back yoke. It is a perspective view which shows the structural example of a magnetic-pole-tooth unit. It is a perspective view which shows the structural example of a magnetic-pole-tooth unit. It is a perspective view which shows the structural example of a base part. It is a side view which shows the other structural example of a back yoke. It is a perspective view which shows the structural example of a base part.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.

(Embodiment 1)
1 and 2 are a perspective view and a side view showing the configuration of the linear motor 1 of the first embodiment. 3 and 4 are a plan view and an exploded perspective view showing a configuration example of the mover 2 in the linear motor 1 of the first embodiment. 1 and 2, only the mover 2 represents a cross section from a direction parallel to the movable direction so that the arrangement of the magnets can be understood.

The linear motor 1 includes a mover 2, a back yoke 3, and an armature 4. A back yoke 3 is disposed opposite to the mover 2 with a gap, and an armature 4 is disposed opposite to the back yoke 3 with a gap between the mover 2. The back yoke 3 and the armature 4 function as a stator.

The elongated mover 2 includes a plurality of permanent magnets 21, a holding frame 22, and a fixed plate 23 as shown in FIG. 4. The juxtaposition direction of the plurality of permanent magnets 21 is the longitudinal direction of the mover 2. Each permanent magnet 21 has a rectangular shape. Each permanent magnet 21 is, for example, a Nd—Fe—B rare earth magnet. Each permanent magnet 21 is magnetized in the thickness direction (vertical direction in FIG. 2), and the magnetization directions of the adjacent permanent magnets 21 and 21 are opposite to each other. That is, in the magnet arrangement, the permanent magnet 21 magnetized in the direction from the back yoke 3 side toward the armature 4 side and the permanent magnet 21 magnetized in the direction from the armature 4 side toward the back yoke 3 side alternately. Is arranged.

As shown in FIG. 4, the holding frame 22 has a rectangular plate shape. The thickness of the holding frame 22 is smaller than the thickness of the permanent magnet 21. The holding frame 22 is provided with a plurality of rectangular holes 221. The holding frame 22 is made of a nonmagnetic material such as SUS or aluminum. The hole 221 has a shape corresponding to the permanent magnet 21. Each permanent magnet 21 is fitted into the hole 221 and fixed to the holding frame 22 with an adhesive. The holes 221 are provided so that the permanent magnets 21 fixed to the holding frame 22 are juxtaposed at an equal pitch. Further, when the permanent magnet 21 is fixed to the holding frame 22, the permanent magnet 21 is fitted into the hole 221 so that the magnetization directions of the adjacent permanent magnets 21 and 21 are opposite to each other. As shown in FIG. 3, each permanent magnet 21 is skewed at an angle θ.

The holding frame 22 is fixed to the fixing plate 23 with an adhesive while the plurality of permanent magnets 21 are inserted and held in the holes 221 of the holding frame 22. The bottom surfaces of the permanent magnets 21 are also bonded to the fixed plate 23. The fixed plate 23 is made of nonmagnetic SUS or the like. As described above, since the magnet array is held by the holding frame 22 and bonded and fixed to the fixing plate 23, the mover 2 has high rigidity and the permanent magnet 21 does not fall off. The mover 2 is disposed in the gap between the back yoke 3 and the armature 4 so that the fixed plate 23 faces the back yoke 3. The fixing plate 23 is not essential and is not necessary when the permanent magnet 21 is sufficiently held by the holding frame 22.

The lengths of the back yoke 3 and the armature 4 in the movable direction (left and right direction in FIG. 2) are substantially equal, and the lengths of the movable element 2 in the movable direction (left and right direction in FIG. 2) are the same. 4 is shorter than the length in 4, and the difference in length is a stroke at which the linear motor 1 can operate. With such a configuration, the edge effect is reduced.

The surface of the back yoke 3 that is made of mild steel, preferably a soft magnetic material (for example, silicon steel plate), that is not opposed to the mover 2 is flat, but the surface of the back yoke 3 that faces the mover 2 is Instead of a flat plate shape, a plurality of rectangular magnetic pole teeth 31 are formed at equal pitches in the movable direction. The height of each magnetic pole tooth 31 is 1/20 or more and 2 or less, preferably 1/10 or more and 1 or less, the formation pitch of the magnetic pole teeth 31. For example, the height of each magnetic pole tooth 31 is about half of the formation pitch of the magnetic pole teeth 31.

In the armature 4, a plurality of rectangular magnetic pole teeth 42 made of a soft magnetic material are integrally provided on a core 41 made of a soft magnetic material at an equal pitch in a movable direction, and a drive coil is provided on each magnetic pole tooth 42. 43 is sown.

The pitch of the magnetic pole teeth 31 in the back yoke 3 is equal to the pitch of the magnetic pole teeth 42 of the armature 4, and the positions of the magnetic pole teeth 31 in the back yoke 3 are the magnetic pole teeth 42 of the armature 4 in the moving direction of the mover 2. The position is the same. Further, the shape of the magnetic pole face of the magnetic pole teeth 31 of the back yoke 3 facing the mover 2 has a rectangular shape substantially the same as the magnetic pole face of the magnetic pole teeth 42 of the armature 4 facing the mover 2, The former magnetic pole area is 0.9 to 1.1 times the latter magnetic pole area. For example, the magnetic pole surface of the magnetic pole tooth 31 and the magnetic pole surface of the magnetic pole tooth 42 have the same rectangular shape and the same area. Further, the gap between the mover 2 and the back yoke 3 is the same as or larger than the gap between the mover 2 and the armature 4. For example, the latter gap is 0.5 mm, and the former gap is 0.5 mm or more. The gap between the mover 2 and the back yoke 3 in this case does not include the thickness of the fixed plate 23 even when the fixed plate 23 is included, and the distance between the mover 2 itself and the back yoke 3 (shortest) Distance). In other words, this gap is a magnetic gap (magnetic gap), and it is not necessary to consider the thickness of the fixed plate 23 that is a non-magnetic material.

The linear motor 1 of the first embodiment has a basic configuration of seven poles and six slots in which seven permanent magnets 21, six magnetic pole teeth 31 and magnetic pole teeth 42 face each other. The form shown in FIGS. 1 and 2 has a 14-pole 12-slot configuration that doubles the basic configuration.

In the linear motor 1 of the first embodiment, the back yoke 3 has a magnetic pole surface having substantially the same shape at the same position in the movable direction as the magnetic pole teeth 42 of the armature 4 on the surface facing the mover 2. Magnetic pole teeth 31 having substantially the same magnetic pole area are formed. Therefore, the magnitude of the suction force generated between the mover 2 and the back yoke 3 is substantially equal to the magnitude of the suction force generated between the mover 2 and the armature 4, and both suction forces are in the vertical direction in FIG. Is effectively canceled out, the suction force acting on the mover 2 as the whole linear motor 1 becomes very small. As described above, in the linear motor 1 according to the first embodiment, the suction force can be significantly reduced without increasing the gap between the mover 2 and the back yoke 3. Therefore, there is no need to increase the gap between the mover 2 and the back yoke 3, so that the thrust is not reduced.

In the linear motor 1 of the first embodiment, as described above, the armature 4 having a plurality of magnetic pole teeth 42 at an equal pitch, and the plurality of magnetic pole teeth 42 of the armature 4 in the movable direction and in the same position. Since the mover 2 is arranged between the back yoke 3 having the magnetic pole teeth 31 and the cogging torque of the magnet arrangement in the direction perpendicular to the movable direction is reduced, the detent force of the mover 2 is reduced. Reduction can be achieved. Further, since the magnet array is held by the holding frame 22 and is fixed to the fixing plate 23, the rigidity of the mover 2 can be increased, so that the permanent magnet 21 is not easily deformed such as bending and bending. However, it contributes to the reduction of the detent force of the mover 2.

In the linear motor 1 of the first embodiment, a plurality of magnetic pole teeth 31 are formed on the back yoke 3, and the shearing region of the driving magnetic flux is generated by the concavo-convex shape facing the mover 2. The back yoke 3 also contributes to the generation of thrust. FIG. 5 is a side view showing the flow of magnetic flux in the linear motor 1 of the first embodiment. In FIG. 5, arrows indicate the flow of magnetic flux. In the linear motor 1, thrust is generated by the shearing of the magnetic flux on the armature 4 side, and the thrust is also generated by the shearing of the magnetic flux on the back yoke 3 side. Is the total. In the linear motor in which the back yoke is flat without forming the magnetic pole teeth 31 as in the first embodiment, no thrust is generated on the back yoke side, and only the thrust due to magnetic flux shearing on the armature side. It becomes.

In the linear motor 1 of the first embodiment, since a gap is also provided between the mover 2 and the back yoke 3, there is a concern that the thrust is reduced by this gap. However, since the thrust can be generated also on the back yoke 3 side as described above, a large thrust can be realized by compensating for the decrease in the thrust caused by the gap.

From the above, in the linear motor 1 of the first embodiment, the suction force acting on the mover 2 can be greatly reduced while maintaining a large thrust. Therefore, the mover 2 hardly bends due to the suction force, and the dimensional accuracy in a processing machine in a semiconductor manufacturing apparatus using the linear motor 1 becomes very high.

Further, in the linear motor 1 of the first embodiment, since the attractive force can be reduced, there is no problem even if the permanent magnet 21 and the holding frame 22 having low rigidity are used. Therefore, it is possible to reduce the size of the mover 2 and to realize a large acceleration as the mover 2 is reduced in weight. Further, since the mover 2 is less worn, the life of the linear motor 1 can be extended.

In the linear motor, in order to move the mover smoothly, it is common to provide a linear guide on the side surface of the mover as described later. However, in the linear motor 1 of the first embodiment, the suction force is small. Therefore, a linear guide having a low rigidity can be used, which also contributes to the miniaturization and long life of the linear motor.

In the linear motor 1 of the first embodiment, the length of the mover 2 is made shorter than the lengths of the back yoke 3 and the armature 4, thereby further reducing the size, weight and speed.

Hereinafter, a specific configuration of the linear motor 1 according to the first embodiment manufactured by the present inventor and characteristics of the manufactured linear motor 1 will be described.

First, the mover 2 was produced. 14 rectangular permanent magnets 21 having a thickness of 5 mm, a width of 12 mm, and a length of 82 mm were cut out from a block of Nd—Fe—B rare earth magnet (B _r = 1.395 T, H _cJ = 1273 kA / m). . The cut out permanent magnet 21 was magnetized in the thickness direction. Next, a holding frame 22 as shown in FIG. 4 was cut out by wire cutting from a SUS plate having a thickness of 3 mm. The cut holding frame 22 was bonded and fixed to a fixing plate 23 made of a SUS plate having a thickness of 0.2 mm. A skew angle θ = 3.2 ° is applied to the 14 permanent magnets 21 coated with adhesive so that the magnetization directions of the adjacent permanent magnets 21 are opposite to each other in the holes 221 of the holding frame 22. Then, the permanent magnet 21 was adhered and fixed to the holding frame 22 and the fixing plate 23. Here, the thickness of the holding frame 22 is set to 3 mm with respect to the thickness of the permanent magnet 21 so that both the weight reduction of the mover 2 and the large rigidity of the magnet arrangement can be realized.

Unlike the above example, the holding frame 22 may be manufactured by a method in which six SUS plates having a thickness of 0.5 mm are punched by pressing and stacked and fixed by caulking. good. In this case, the manufacturing cost can be reduced.

Next, a back yoke 3 was produced. FIG. 6 is a view showing a side shape of the back yoke 3 in the linear motor 1 according to the first embodiment.

A block having dimensions as shown in FIG. 6 is cut out from mild steel (JIS standard G3101 type symbol SS400 material) and 18 magnetic pole teeth 31 having the same shape (width: 6 mm, height: 3 mm, length: 82 mm, A back yoke 3 having a magnetic pole area of 492 mm ² ) at an equal pitch (15.12 mm) was produced.

Next, an armature 4 was produced. FIG. 7 is a plan view showing an armature material used for manufacturing the armature 4 in the linear motor 1 of the first embodiment. 164 pieces of an armature material 44 having a shape as shown in FIG. 7 are cut out from a 0.5 mm-thick silicon steel plate (JIS standard C2552 type symbol 50A800 material), and the cut out 164 pieces are overlapped with a CO ₂ laser. A block body having a width of 82 mm, a height of 31 mm, and a length of 263.04 mm (18 core teeth of the same shape on the core 41 (width: 6 mm, height: 25 mm, length: 82 mm, magnetic pole) An area having an area of 492 mm ² ) at an equal pitch (15.12 mm) was obtained.

Next, a winding was inserted into this block body. FIG. 8 is a diagram illustrating windings of the armature 4 in the linear motor 1 according to the first embodiment. A drive coil 43 was obtained by impregnating an arm portion of each magnetic pole tooth 42 of the armature 4 with an enamel-coated conductor wire having a diameter of 2 mm 17 times by impregnating with varnish.

8, U, V, and W represent the U-phase, V-phase, and W-phase, respectively, of the three-phase AC power supply, and the coils of each phase are all connected in series. The U, V, and W coils are wired so that the current flows clockwise when viewed from above, and the -U, -V, and -W coils are wired so that the current flows counterclockwise when viewed from above. Thus, an armature 4 was produced. Six U coils, -U coils, V coils, -V coils, W coils, and -W coils were connected in a star connection to a three-phase AC power source.

Next, the manufactured back yoke 3 and armature 4 were fixed using a jig so that the distance between them was kept constant at 6 mm. Although the gap between the back yoke 3 and the armature 4 is fixed to 6 mm, the gap can be adjusted after the linear motor 1 is assembled. Next, after a linear guide (not shown) is attached to the side surface of the mover 2, the gap between the back yoke 3 and the armature 4 is separated from the back yoke 3 and the armature 4 by a predetermined distance, and the thickness is 5 mm. The linear motor 1 was produced by inserting the mover 2. At this time, the distance of the gap between the mover 2 and the magnetic pole teeth 31 of the back yoke 3 and the distance of the gap between the mover 2 and the magnetic pole teeth 42 of the armature 4 were both 0.5 mm. Further, a load cell was provided between the linear guide and the armature 4 so that the suction force could be measured.

Since the gap between the back yoke 3 and the armature 4 can be adjusted, the distance between the mover 2 and the armature 4 (magnetic pole teeth 42) is constant, and the mover 2 and the back yoke 3 ( The distance of the gap with the magnetic pole teeth 31) can be arbitrarily set to be variable. It should be noted that by adjusting the insertion position of the mover 2 into the gap between the back yoke 3 and the armature 4, the distance between the mover 2 and the back yoke 3 (the magnetic pole teeth 31), and the mover 2 and the electric machine It is also possible to set the ratio of the gap distance to the child 4 (the magnetic pole teeth 42) to a desired value.

In addition, as a mechanism for adjusting the gap between the linear guide that supports the armature 4 and the mover 2 and between the armature 4 and the back yoke 3, a mechanism for adjusting the height by inserting a gap adjusting screw or a cross-sectional shape It is possible to employ a mechanism for adjusting the height by inserting a shim plate having a taper shape with a screw.

9A and 9B are diagrams showing a configuration of the linear motor 1 as an example of the first embodiment manufactured as described above, FIG. 9A is a top view thereof, and FIG. 9B is a side view thereof. In FIG. 9B, the white arrow indicates the magnetization direction of the permanent magnet 21, and the solid arrow indicates the movable direction of the mover 2. The details of the production specifications of the linear motor 1 are as follows.

Magnetic pole configuration: 7 poles, 6 slots Permanent magnet 21 Material: Nd-Fe-B rare earth magnet (NMX made by Hitachi Metals)
-S49CH material)
The shape of the permanent magnet 21: thickness 5.0mm, width 12mm, length 82mm
Permanent magnet 21 pitch: 12.96 mm
Skew angle of the permanent magnet 21: 3.2 °
Shape of back yoke 3: thickness 6.0 mm, width 90 mm, length 263.04 mm
Back Yoke 3 Material: Mild Steel (JIS Standard G3101 Type Code SS400 Material)
Shape of magnetic pole teeth 31: width 6.0 mm, height: 3.0 mm, length: 82 mm
Pitch of magnetic pole teeth 31: 15.12 mm
Core 41 physique: height 31mm, width 82mm, length 263.04mm
Material of core 41: silicon steel plate (JIS standard C2552 type symbol 50A800 material)
The shape of the magnetic pole teeth 42: width 6.0 mm, height: 25 mm, length: 82 mm
Pitch of magnetic pole teeth 42: 15.12 mm
Drive coil 43 shape: width 15.12 mm, height 23 mm, length 91.12 mm
Winding thickness of drive coil 43: 4.06 mm
Winding diameter and number of windings of drive coil 43: Diameter 2 mm, 17 turns Winding resistance (1): 0.0189Ω
Mover 2 mass: 516.6 g

In the linear motor 1 described above, the length (190 mm) of the mover 2 is shorter than the lengths of the back yoke 3 and the armature 4 (both 263.04 mm). The pitch of the magnetic pole teeth 31 in the back yoke 3 and the pitch of the magnetic pole teeth 42 in the armature 4 are all equal to 15.12 mm, and the magnetic pole teeth 31 and the magnetic pole teeth 42 are at the same position in the movable direction.

The shape of the magnetic pole face of the magnetic pole teeth 31 facing the magnet arrangement and the shape of the magnetic pole face of the magnetic pole teeth 42 facing the magnet arrangement are rectangular with the same dimensions. That is, the width of the magnetic pole teeth 31 (the dimension in the movable direction) and the width of the magnetic pole teeth 42 (the dimensions in the movable direction) are both 6 mm and are equal, and the magnetic pole area of the magnetic pole teeth 31 facing the magnet arrangement and the magnet arrangement. The magnetic pole areas of the opposing magnetic pole teeth 42 are all equal to 492 mm ² .

The linear motor 1 assembled in this way is installed on a test bench for thrust measurement, and is driven by a three-phase constant current power source synchronized with the position of the mover 2 (magnet arrangement) to move the mover 2 to generate thrust and suction. The force was measured.

FIG. 10 is a graph showing the thrust fluctuation with respect to the electrical angle of the linear motor 1 as an example of the first embodiment. This variation in thrust is the thrust against the position of the mover 2 when the driving magnetomotive force (= the magnitude of the driving current × the number of turns of the driving coil 43) is 1200 A (the three-phase combined thrust of the U phase, V phase, and W phase). Represents changes. In FIG. 10, the horizontal axis represents the electrical angle [°], and the vertical axis represents the thrust [N]. In the figure, a represents the thrust by the armature 4, b in the figure represents the thrust by the back yoke 3, and c in the figure represents the total thrust (thrust added by the thrust by the armature 4 and the thrust by the back yoke 3). Yes. As shown in FIG. 10, it can be seen that a substantially constant large thrust is obtained over the entire region.

FIG. 11 is a graph showing the thrust characteristics of the linear motor 1 as an example of the first embodiment. This thrust characteristic represents a characteristic when the current applied to the drive coil 43 is changed. In FIG. 11, the horizontal axis represents the drive magnetomotive force [A], the left vertical axis represents the thrust [N], and the right vertical axis represents the thrust magnetomotive force ratio [N / A]. In the figure, a represents the thrust, and b in the figure represents the thrust magnetomotive force ratio. In this linear motor 1, the thrust proportional limit (thrust magnetomotive force ratio is reduced by 10%) is 1000 N when the driving magnetomotive force is 1200A.

FIG. 12 is a graph showing the attractive force characteristics of the linear motor 1 as an example of the first embodiment. This attraction force characteristic represents a characteristic when the current applied to the drive coil 43 is changed. In FIG. 12, the horizontal axis represents the driving magnetomotive force [A], and the vertical axis represents the attractive force [N]. The suction force indicates that the mover 2 is attracted to the armature 4 side on the + side, and the mover 2 is attracted to the back yoke 3 side on the − side. As the driving magnetomotive force increases, the attractive force increases. For example, when the driving magnetomotive force is 1200 A, the movable element 2 is attracted to the back yoke 3 side with an attractive force of about 290 N.

By the way, in order to evaluate the linear motor 1 of the first embodiment in comparison with the conventional linear motor, two types of linear motors (first conventional example and second conventional example) are manufactured as conventional examples, and those linear motors 1 are manufactured. Characteristics (thrust force and suction force) were measured.

First, the configuration of the first conventional example will be described. FIG. 13 is a side view showing the configuration of the linear motor of the first conventional example. The first conventional example is a linear motor (integrated linear motor) having a configuration according to Patent Document 1 or 2.

The linear motor 50 of the first conventional example includes a mover 51 in which a magnet array 52 and a back yoke 53 are integrated, and an armature 54 that is disposed to face the mover 51 with a gap. In the first conventional example, a structure in which the magnet array 52 and the back yoke 53 are integrated functions as a mover, and the armature 54 functions as a stator.

The configuration of the magnet array 52 is the same as the configuration of the magnet array of the mover 2 described above. That is, the magnet array 52 is configured by holding and fixing a plurality of rectangular permanent magnets 55 on a nonmagnetic material holding frame at an equal pitch and installing them in a movable direction (left-right direction in FIG. 13). 55 is magnetized in the thickness direction (vertical direction in FIG. 13), and the magnetization directions of the adjacent permanent magnets 55, 55 are opposite to each other. In the linear motor 50 of the first conventional example, the magnet array 52 is bonded to a flat steel back yoke 53 made of mild steel. The configuration of the armature 54 is the same as the configuration of the armature 4 described above, and a plurality of magnetic pole teeth 57 are integrally provided on the core 56 at an equal pitch in the movable direction. The drive coil 58 is wound on the front.

14A and 14B are diagrams showing the configuration of the linear motor 50 of the first conventional example, FIG. 14A is a top view thereof, and FIG. 14B is a side view thereof. In FIG. 14B, the white arrow indicates the magnetization direction of the permanent magnet 55, and the solid arrow indicates the movable direction of the mover 51. In addition, the magnitude | size of the clearance gap between the needle | mover 51 and the armature 54 was 0.5 mm or 1 mm. Details of the production specifications of the linear motor 50 are as follows.

Magnetic pole configuration: 7 poles, 6 slots Permanent magnet 55 Material: Nd-Fe-B rare earth magnet (NMX made by Hitachi Metals)
-S49CH material)
Shape of the permanent magnet 55: thickness 5.0mm, width 12mm, length 82mm
Permanent magnet 55 pitch: 12.96 mm
Skew angle of permanent magnet 55: 3.2 °
Shape of the back yoke 53: thickness 6.0mm, width 90mm, length 190mm
Material of back yoke 53: Mild steel (JIS standard G3101 type symbol SS400 material)
Core 56 physique: height 31mm, width 82mm, length 263.04mm
Material of core 56: silicon steel plate (JIS standard C2552 type symbol 50A800 material)
Shape of magnetic pole teeth 57: width 6.0 mm, height: 25 mm, length: 82 mm
Pitch of magnetic pole teeth 57: 15.12 mm
The shape of the drive coil 58: width 15.12mm, height 23mm, length 91.12mm
Winding thickness of drive coil 58: 4.06 mm
Winding diameter and number of windings of the drive coil 58: Diameter 2 mm, 17 turns Winding resistance (1): 0.0189Ω
Mass of mover 51 (magnet arrangement 52 + back yoke 53): 1321.01 g

The length of the mover 51 (integrated configuration of the magnet array 52 and the back yoke 53) in the movable direction (left-right direction in FIG. 13) is shorter than the length of the armature 54, and the difference in length is the difference of the linear motor 50. The stroke is operable.

Next, the configuration of the second conventional example will be described. FIG. 15 is a side view showing the configuration of the linear motor of the second conventional example. The second conventional example is a linear motor (separated linear motor) having a configuration according to Patent Documents 3 to 6. In FIG. 15, only the magnet array 62 represents a cross section from a direction parallel to the movable direction so that the arrangement of the magnets can be understood.

The linear motor 60 of the second conventional example has a magnet array 62, a back yoke 63 disposed opposite to the magnet array 62 with a gap therebetween, and a counter arrangement opposite to the back yoke 63 with a gap formed between the magnet arrays 62. Armature 64. Only the magnet array 62 functions as a mover, and the back yoke 63 and the armature 64 function as a stator.

The configuration of the magnet array 62 is the same as the configuration of the magnet array of the mover 2 described above. That is, the magnet array 62 is configured by a plurality of rectangular permanent magnets 65 being held and fixed on a nonmagnetic material holding frame at an equal pitch and installed in a movable direction (left and right direction in FIG. 15). 65 is magnetized in the thickness direction (vertical direction in FIG. 15), and the magnetization directions of the adjacent permanent magnets 65, 65 are opposite to each other. The back yoke 63 made of mild steel has a flat plate shape not only on the surface that does not face the magnet array 62 but also on the surface that faces the magnet array 62, and the magnetic pole teeth like the linear motor 1 of the first embodiment. Does not exist. The configuration of the armature 64 is the same as the configuration of the armature 4 described above, and a plurality of magnetic pole teeth 67 are integrally provided on the core 66 at an equal pitch in the movable direction. The drive coil 68 is wound on the front.

16A and 16B are diagrams showing the configuration of the linear motor 60 of the second conventional example, FIG. 16A is a top view thereof, and FIG. 16B is a side view thereof. In FIG. 16B, the white arrow indicates the magnetization direction of the permanent magnet 65, and the solid arrow indicates the movable direction of the magnet array 62 (movable element). Note that the size of the gap between the magnet array 62 and the back yoke 63 and the size of the gap between the magnet array 62 and the armature 64 were both 0.5 mm. Details of the production specifications of the linear motor 60 are as follows.

Magnetic pole configuration: 7 poles, 6 slots Permanent magnet 65 Material: Nd-Fe-B rare earth magnet (NMX made by Hitachi Metals)
-S49CH material)
Permanent magnet 65 shape: thickness 5.0 mm, width 12 mm, length 82 mm
Permanent magnet 65 pitch: 12.96 mm
Skew angle of permanent magnet 65: 3.2 °
Back yoke 63 shape: thickness 6.0 mm, width 90 mm, length 215 mm
Material of back yoke 63: Mild steel (JIS standard G3101 type symbol SS400 material)
Core 66 physique: height 31mm, width 82mm, length 263.04mm
Material of core 66: silicon steel plate (JIS standard C2552 type symbol 50A800 material)
Shape of magnetic pole teeth 67: width 6.0 mm, height: 25 mm, length: 82 mm
Pitch of magnetic pole teeth 67: 15.12 mm
Drive coil 68 shape: width 15.12 mm, height 23 mm, length 91.12 mm
Winding thickness of drive coil 68: 4.06 mm
Winding diameter and number of turns of drive coil 68: Diameter 2 mm, 17 turns Winding resistance (1 piece): 0.0189Ω
Mass of mover (magnet array 62): 516.6 g

The length of the magnet array 62 in the movable direction (left-right direction in FIG. 15) is shorter than the length of the armature 64, and the difference in length is an operable stroke of the linear motor 60.

Comparison of characteristics (thrust force and suction force) in the first conventional example, the second conventional example, and the first embodiment will be described.

FIG. 17 is a graph showing average thrusts in the linear motors of the first conventional example, the second conventional example, and the first embodiment. FIG. 17 represents the average thrust [N] when the driving magnetomotive force is 1200 A. FIG. 18 is a graph showing the average suction force in the linear motors of the first conventional example, the second conventional example, and the example. FIG. 18 shows the average attractive force [N] when the driving magnetomotive force is 1200A. Here, the average thrust and the average attractive force are obtained by measuring (calculating) 25 thrusts and attractive forces at 15 ° intervals in the range of the U-phase electrical angle of 0 ° to 360 °, and calculating the average.

In FIG. 17 and FIG. 18, A is a first conventional example in which the magnet array 52 and the back yoke 53 are integrated, and the linear motor 50 (hereinafter referred to as “the gap between the movable element 51 and the armature 54” is 0.5 mm). B is a linear motor 50 (hereinafter referred to as a linear motor) in which a gap between the mover 51 and the armature 54 is 1 mm in the first conventional example in which the magnet array 52 and the back yoke 53 are integrated. 50B), and C is the second conventional example in which the magnet array 62 and the back yoke 63 are separated from each other, and the gap between the magnet array 62 and the back yoke 63, and the magnet array 62 and the armature 64 The linear motor 60 has a gap of 0.5 mm, and D is an example of Embodiment 1 in which magnetic pole teeth 31 are formed on the back yoke 3 separated from the mover 2 (magnet arrangement). back Gap between the over click 3, and a linear motor 1 that both was 0.5mm the gap between the mover 2 and the armature 4.

The linear motor 50A (A in the figure) of the first conventional example has the largest thrust of 1030N, but the suction force is 4200N, which is a large value about four times the thrust. In the linear motor 50B (B in the figure) as a countermeasure for reducing the suction force, the thrust obtained is significantly reduced to 909N, whereas the suction force is not reduced so much and is 3360N. Therefore, it is understood that it is not a sufficient measure.

In the linear motor 60 of the second conventional example (C in the figure), a relatively large thrust of 980 N can be obtained, but the suction force is attracted to the back yoke 63 side by a large force as large as 1712 N. Sufficient reduction has not been made.

On the other hand, in the linear motor 1 (D in the figure) as an example of the first embodiment, a large thrust of 1000 N, which is comparable to the linear motor 50A, can be obtained. Further, the suction force can be greatly reduced to 290 N (about 1/14 of the linear motor 50A) on the back yoke 3 side. Therefore, in the linear motor 1 as an example of the first embodiment, it has been proved that the suction force can be significantly reduced while maintaining a large thrust.

By the way, in the linear motor 1 as an example of the first embodiment, as shown in FIG. 12, the magnitude of the attractive force varies depending on the magnitude of the driving magnetomotive force. Therefore, if the size of the gap between the mover 2 and the back yoke 3 is adjusted in accordance with a frequently used thrust region (drive magnetomotive force), the attractive force can be further reduced.

In the example of the first embodiment described above, the gap between the mover 2 and the back yoke 3 and the gap between the mover 2 and the armature 4 are both equal to 0.5 mm. In this example, the gap between the mover 2 and the armature 4 remains 0.5 mm, and the gap between the mover 2 and the back yoke 3 is 0.74 mm. Other configurations are the same as the above-described example.

FIG. 19 is a graph showing the thrust characteristics of the linear motor 1 of another example of the first embodiment, and FIG. 20 is a graph showing the attractive force characteristics of the linear motor 1 of another example of the first embodiment. . In FIG. 19, the horizontal axis represents the drive magnetomotive force [A], the left vertical axis represents the thrust [N], the right vertical axis represents the thrust magnetomotive force ratio [N / A], a is the thrust, and b is the thrust magnetomotive force. Each represents a ratio. In FIG. 20, the horizontal axis represents the drive magnetomotive force [A], and the vertical axis represents the attractive force [N].

In another example, the thrust is 978 N when the driving magnetomotive force is 1200 A, which is a little lower than the above-described example, but the attractive force is only 18 N when the driving magnetomotive force is 1200 A and is almost zero. Has been realized. This is a suction force at which the linear guide, the mover, and the surrounding structure can be ignored due to the deformation and life reduction due to the suction force. Therefore, when using with the driving magnetomotive force of 1200 A vicinity, it turns out that the linear motor 1 of another example is more suitable for the objective of reduction of an attractive force compared with the example mentioned above.

As still another example of the first embodiment, the linear motor 1 in which the gap between the mover 2 and the armature 4 remains 0.5 mm and the gap between the mover 2 and the back yoke 3 is 0.66 mm. Was made. Other configurations are the same as the above-described example.

FIG. 21 is a graph showing thrust characteristics of the linear motor 1 of still another example of the first embodiment, and FIG. 22 is a graph showing suction force characteristics of the linear motor 1 of still another example of the first embodiment. It is. In FIG. 21, the horizontal axis represents the driving magnetomotive force [A], the left vertical axis represents the thrust [N], the right vertical axis represents the thrust magnetomotive force ratio [N / A], a is the thrust, and b is the thrust magnetomotive force. Each represents a ratio. In FIG. 22, the horizontal axis represents the driving magnetomotive force [A], and the vertical axis represents the attractive force [N].

In still another example, when the driving magnetomotive force is 1200 A, the thrust is 984 N, which is a little lower than the above-described example, but the attractive force is only 5 N when the driving magnetomotive force is 600 A, and is almost the same. Zero has been realized. Therefore, it can be seen that when used with a driving magnetomotive force in the vicinity of 600 A, the linear motor 1 of still another example is optimal for reducing the attractive force.

From the above, by setting the size of the gap between the mover 2 and the back yoke 3 optimally according to the frequently used usage area, the suction force can be greatly reduced and almost zero can be achieved. . As a result, it is possible to prevent deterioration in dimensional accuracy due to bending of the mover 2 (magnet arrangement), a decrease in life due to an excessive load on the linear guide, and the like.

In the above-described embodiment, the example in which the size of the gap between the mover 2 and the armature 4 is fixed and the size of the gap between the mover 2 and the back yoke 3 is changed has been described. Further, an example in which the size of the gap between the mover 2 and the armature 4 is changed by fixing the size of the gap between the mover 2 and the back yoke 3, the size of the gap between the back yoke 3 and the armature 4. It is also possible to realize a suction force close to zero by, for example, changing the position of the mover 2 while fixing.

In the above-described embodiment, the linear motor 1 having the structure in which the movable element 2 is shorter than the armature 4 has been described. On the contrary, the linear motor having the structure in which the movable element is longer than the armature is also described in the present invention. The feature (formation of magnetic pole teeth on the back yoke) is applicable.

(Basic example of Embodiment 2)
23 and 24 are a perspective view and a side view showing a configuration example of the linear motor 1 of the second embodiment. 23 and 24, only the mover 2 represents a cross section from a direction parallel to the movable direction so that the arrangement of the magnets can be understood.

As in the first embodiment, the linear motor 1 according to the second embodiment includes the mover 2, the back yoke 3, and the armature 4, and the back yoke 3 and the armature 4 function as a stator.

The configurations of the mover 2 and the armature 4 in the linear motor 1 of the second embodiment are the same as the configurations of the mover 2 and the armature 4 in the linear motor 1 of the first embodiment described above. The description is omitted.

In the linear motor 1 of the second embodiment, the configuration of the back yoke 3 is different from that of the linear motor 1 of the first embodiment. The back yoke 3 includes magnetic pole teeth 31 and a base plate 32. The base plate 32 has a rectangular plate shape. The magnetic pole teeth 31 are fixed to the base plate 32. The magnetic pole teeth 31 are fixed so that a part thereof protrudes from the base plate 32. The shape of the protruding part is a rectangular parallelepiped shape. The plurality of magnetic pole teeth 31 are arranged at an equal pitch along the longitudinal direction of the base plate 32. For example, the magnetic pole teeth 31 are formed of a laminated silicon steel plate as will be described later. The base plate 32 is made of carbon steel such as SS400, for example.

The back yoke 3 and the armature 4 are arranged to face each other with a gap. The mover 2 is disposed in the gap. The first surface of the mover 2 faces the back yoke 3 with a gap. The second surface facing the first surface of the mover 2 faces the armature 4 with a gap.

As shown in FIG. 24, the lengths of the back yoke 3 and the armature 4 in the movable direction (left-right direction in FIG. 24) are substantially equal. Further, the pitch of the magnetic pole teeth 31 in the back yoke 3 is equal to the pitch of the magnetic pole teeth 42 of the armature 4. The positions of the magnetic pole teeth 31 in the back yoke 3 are the same as the positions of the magnetic pole teeth 42 of the armature 4 in the moving direction of the mover 2. Further, the magnetic pole surface of the magnetic pole tooth 31 and the magnetic pole surface of the magnetic pole tooth 42 have the same rectangular shape and the same area. Further, the gap between the mover 2 and the back yoke 3 is substantially the same as the gap between the mover 2 and the armature 4.

In the mover 2, the magnetization directions of the adjacent permanent magnets 21 and 21 are opposite to each other. When the mover 2 is arranged in the gap between the back yoke 3 and the armature 4, the permanent magnet 21 magnetized in the direction from the back yoke 3 side to the armature 4 side, and from the armature 4 side to the back yoke 3 side. The permanent magnets 21 magnetized in the direction are alternately arranged.

During the operation of the linear motor 1, an attractive force is generated between the magnetic pole teeth 31 of the back yoke 3 and the permanent magnet 21 of the mover 2. An attractive force is also generated between the magnetic pole teeth 42 of the armature 4 and the permanent magnet 21 of the mover 2. Two suction forces acting on the mover 2 are in opposite directions. By adjusting the magnetic circuit such that the magnetic pole surface of the magnetic pole tooth 31 and the magnetic pole surface of the magnetic pole tooth 42 have the same rectangular shape and the same area, the magnitude of the attractive force can be made substantially equal. Thereby, the attractive force generated between the magnetic pole teeth 31 and the permanent magnet 21 and the attractive force generated between the magnetic pole teeth 42 and the permanent magnet 21 can be balanced. That is, the two suction forces can be canceled out. If it is difficult to balance the two attractive forces due to factors such as processing errors and assembly errors, the distance between the magnetic pole teeth 31 and the permanent magnet 21 or the distance between the magnetic pole teeth 42 and the permanent magnet 21 is adjusted. To balance the two suction forces.

As described above, the linear motor 1 according to the second embodiment has the same configuration as the linear motor 1 according to the first embodiment described above. As in the linear motor 1 of the first embodiment, the suction force acting on the mover 2 can be greatly reduced while maintaining a large thrust. Also in the linear motor 1 according to the second embodiment, the detent force of the mover 2 can be reduced as in the linear motor 1 according to the first embodiment.

Hereinafter, the configuration of the back yoke 3 that is a feature of the second embodiment will be described in detail. FIG. 25 is a perspective view illustrating a configuration example of the magnetic pole teeth 31 included in the back yoke 3. The magnetic pole tooth 31 has a T-shaped cross section and has two projecting portions 31a and 31a projecting from the bottom portion (lower side in FIG. 25) in the lateral direction. (For this reason, in FIG. 25, the protrusions 31 a and 31 a are portions that engage with recesses 32 a and 32 a of an ant groove 321 described later). During the operation of the linear motor 1, the short direction of the magnetic pole teeth 31 is parallel to the movable direction of the mover 2.

The magnetic pole teeth 31 are formed by laminating magnetic pole pieces 311. The pole piece 311 includes an engaging protrusion 311a formed by cutting out a part of a rectangular plate shape. The pole piece 311 is formed of a thin plate such as silicon steel having soft magnetism. The stacked magnetic pole pieces 311 are fixed by heat welding or caulking. In the case of heat welding, for example, first, a surface of the pole piece 311 is coated with a thermosetting adhesive or a heat-welding coating is applied, and then heated while applying pressure to the plate surface after lamination. . The pole pieces 311 are fixed by heating.

Note that the eddy current loss decreases as the thickness of the magnetic pole piece 311 constituting the magnetic pole tooth 31 is reduced, that is, as the number of the magnetic pole pieces 311 is increased. In consideration of the strength and assembling work, the thickness of the pole piece 311 is preferably about 0.2 to 0.5 mm. The number and thickness of the magnetic pole pieces 311 constituting the magnetic pole teeth 31 may be appropriately designed according to required specifications.

FIG. 26 is a partial perspective view showing a configuration example of the base plate 32 included in the back yoke 3. FIG. 26 is drawn upside down from FIGS. 24 and 25 for convenience of explanation. The base plate 32 is provided with dovetail grooves 321 along the short direction. The dovetail 321 has a shape corresponding to the protruding portion 311 a of the magnetic pole piece 311 (the protruding portion 31 a of the magnetic pole tooth 31). The dovetail 321 has a recess 32a corresponding to the protrusion 311a (protrusion 31a). As shown in FIGS. 24 and 25, the base plate 32 is formed with a plurality of dovetail grooves 321. The plurality of dovetail grooves 321 are provided at an equal pitch along the movable direction of the mover 2. The arrangement direction of the plurality of dovetail grooves 321 is a direction parallel to the movable direction of the mover 2 when the linear motor 1 is operated.

FIG. 27 is a partial perspective view of the back yoke 3. Similarly to FIG. 26, for the convenience of explanation, it is drawn with the up and down directions of FIGS. 24 and 25 reversed. In the back yoke 3, the protruding portion 31 a of the magnetic pole tooth 31 is engaged with the dovetail groove 321.

The fixing of the magnetic pole teeth 31 to the base plate 32 is performed as follows, for example. Adhesive is applied to one or both of the dovetail 321 and the magnetic pole teeth 31. Using a jig or the like, the magnetic pole teeth 31 are fitted into the dovetail groove 321 for positioning. When the adhesive is cured, remove the jig. The fixing method is not limited to this. Other methods may be used as long as the pitch of the magnetic pole teeth 31 and the amount of protrusion of the magnetic pole teeth 31 from the base plate 32 can be fixed within a predetermined error range.

The linear motor 1 generates magnetic flux that flows through the magnetic pole teeth 42 of the armature 4, the permanent magnet 21 of the mover 2, and the magnetic pole teeth 31 of the back yoke 3 by applying a three-phase alternating current to the drive coil 43 of the armature 4. To do. The attraction force generated between the mover 2 and the armature 4 by the generated magnetic flux and the attraction force generated between the mover 2 and the back yoke 3 become the thrust of the mover 2, and the mover 2 moves. .

Next, the reduction of eddy current will be described. FIG. 28 is a partial side view of the linear motor 1. In FIG. 28, an example of the flow of magnetic flux is indicated by a solid line arrow, and an example of eddy current is indicated by a dotted line arrow. As shown in FIG. 28, in the magnetic pole teeth 31, the magnetic flux flows in the vertical direction on the paper. That is, it flows in a direction parallel to the plate surface of the magnetic pole piece 311 constituting the magnetic pole tooth 31. The eddy current tends to flow in a direction that prevents the magnetic flux from changing on a plane perpendicular to the direction in which the magnetic flux flows. That is, in the case shown in FIG. 28, it tends to flow counterclockwise and orthogonal to the direction in which the magnetic flux flows. The direction of the eddy current is a direction that tries to penetrate the plate surface of the magnetic pole piece 311 constituting the magnetic pole tooth 31. However, the magnetic pole teeth 31 are formed by laminating a plurality of magnetic pole pieces 311 and the electric resistance between the magnetic pole pieces 311 is large, so that eddy current can be reduced. Further, when an insulating film is applied to the plate surface (front surface) of the magnetic pole piece 311, the eddy current flowing between the magnetic pole pieces 311 can be further reduced.

29A and 29B are graphs showing an example of Joule loss due to eddy current, FIG. 29A is a graph showing Joule loss of a linear motor according to a related technique, and FIG. 29B is a linear motor in a basic example of the second embodiment. It is a graph which shows 1 Joule loss. The difference in configuration between the linear motor according to the related technology and the linear motor in the second embodiment is as follows. The former does not have a laminated structure of magnetic pole teeth. For example, the magnetic pole teeth in the former are soft magnetic blocks. Alternatively, the base plate 32 and the magnetic pole teeth 31 may be integrally formed of a soft magnetic material. On the other hand, in the latter, the magnetic pole teeth 31 have a laminated structure. Other conditions, the structure and dimensions of the linear motor, the number of coil turns, and the driving conditions were the same. For example, the driving current of the coil is 70.6 A, and the moving speed of the mover is 1000 mm / s.

29A and 29B, the horizontal axis is an electrical angle indicating the position of the mover 2. The unit of the horizontal axis is degree (°). The vertical axis in FIGS. 29A and 29B is Joule loss due to eddy current. The unit is watt (W). The graph attached with the back yoke shows the Joule loss at the back yoke. As shown in FIG. 29A, in a linear motor according to a related technology that does not have a laminated structure of magnetic pole teeth, the Joule loss at the back yoke is around 80 W, whereas the magnetic pole teeth 31 have a laminated structure. In the linear motor 1, the Joule loss in the back yoke 3 is reduced to about 50W.

29A and 29B, the graphs labeled U, V, and W show the Joule loss due to energization generated in the coil U phase, V phase, and W phase, respectively, in absolute values. In FIGS. 29A and 29B, the Joule loss in the coil due to energization of the coil is the same, but there is a large difference in the Joule loss in the back yoke. This result is an example showing that Joule loss due to eddy currents can be reduced when a laminated structure is used instead of a laminated structure of magnetic pole teeth under the same size and shape, and the linear motor size and linear motor speed are reduced. However, the absolute value of Joule loss due to eddy current changes, but the ratio of both effects at the same speed is maintained.

The linear motor 1 in Embodiment 2 has the following effects. The magnetic pole teeth 31 are formed by laminating magnetic pole pieces 311 formed of silicon steel plates. Therefore, the direction of the eddy current is a direction to penetrate the plate surface. At this time, the electric resistance in the eddy current direction in the magnetic pole teeth 31 is caused by the gap between the surfaces of the magnetic pole pieces 311, the contact resistance between the magnetic pole pieces, the oxide film formed on the surface of the magnetic pole pieces 311, etc. It is larger than the case where it is formed with. Therefore, the eddy current flowing through the magnetic pole teeth 31 can be reduced. Note that the surface (stacked surface) of the pole piece 311 may be subjected to an insulation process such as forming a coating of an insulating material. When the insulation process is performed, eddy currents can be further reduced between the silicon steel plates.

In the second embodiment, the magnetic pole teeth 31 of the back yoke 3 have a laminated structure. For example, when the entire back yoke is formed of a laminated steel plate, there is a concern that the rigidity is lowered. In this case, the back yoke 3 may be bent due to the suction force generated between the movable element 2 and the back yoke 3. However, in the basic example, only the magnetic pole teeth 31 have a laminated structure, and the base plate 32 to which the magnetic pole teeth 31 are fixed is not a laminated structure. Therefore, the bending of the back yoke 3 is based on a related technique (when the magnetic pole teeth 31 and the base plate 32 are each formed of a soft magnetic material, or when the magnetic pole teeth 31 and the base plate 32 are integrally formed of a soft magnetic material). Compared with, it is slight.

(First Modification of Embodiment 2)
The first modification relates to a form in which a part of the base plate constituting the back yoke 3 has a laminated structure. FIG. 30 is a side view showing another configuration example of the back yoke 3. The back yoke 3 includes a base portion 33 and a magnetic pole tooth block 34. The magnetic pole tooth block 34 includes a fitted portion 34 a and a plurality of magnetic pole teeth 31.

FIG. 31 is a perspective view showing a configuration example of the magnetic pole tooth block 34. The magnetic pole tooth block 34 is formed by laminating a plurality of magnetic pole tooth pieces (plate-like members) 341. The stacking direction of the magnetic pole tooth pieces 341 is a direction that intersects the arrangement direction of the magnetic pole teeth 31. The magnetic pole tooth piece 341 includes a fitted portion 341a, a connecting portion 341b, and a plurality of protruding portions 341c. The fitted portion 341a has an inverted trapezoidal cross section. The fitted portion 341 a is a portion that becomes the fitted portion 34 a of the magnetic pole tooth block 34. The protrusion 341c has a rectangular cross section. The plurality of protrusions 341 c are formed at an equal pitch in the longitudinal direction of the magnetic pole piece 341. The protruding portion 341 c is a portion that becomes the magnetic pole teeth 31 of the magnetic pole tooth block 34. The connecting portion 341b is a portion located between the fitted portion 341a and the protruding portion 341c in the height direction of the magnetic pole tooth piece 341. The connecting portion 341b connects the plurality of protruding portions 341c. The magnetic pole tooth piece 341 is made of, for example, a silicon steel plate. The connecting portion 341b is a plate-like member that constitutes a laminated portion that becomes a part of the base portion of the back yoke 3. The protruding portion 341 c is a plate-like member that constitutes the magnetic pole teeth 31. The magnetic pole tooth piece 341 is obtained by integrating two plate-like members.

FIG. 32 is a perspective view showing a configuration example of the base portion 33. The base portion 33 shown in FIG. 32 is inverted upside down from the base portion 33 shown in FIG. The base part 33 has a rectangular plate shape. The base portion 33 has a fitting groove 33a having a trapezoidal cross section.

The fitted portion 34 a of the magnetic pole tooth block 34 is fitted into the fitting groove 33 a of the base portion 33. In the base portion 33, the length of the movable element 2 in the movable direction may be set according to the length of the magnetic pole tooth block 34 in the movable direction. The magnetic pole tooth block 34 is fixed to the base portion 33 as follows. After the adhesive is applied to one or both of the fitting groove 33a and the fitting portion 34a, the fitting is performed. Thereby, the base part 33 and the magnetic pole tooth block 34 are fixed. As a result, the back yoke 3 is formed.

Next, the reduction of eddy current will be described. FIG. 33 is a partial side view of the linear motor 1. In FIG. 33, an example of the flow of magnetic flux is indicated by a solid arrow, and an example of an eddy current is indicated by a dotted arrow. The reduction of the eddy current in the magnetic pole teeth 31 is the same as that in the basic example described above, and thus the description thereof is omitted. Here, the reduction of the eddy current at the connection portion 341b of the magnetic pole tooth block 34 will be described. As shown in FIG. 33, the magnetic flux flows in the left-right direction on the paper surface at the connecting portion 341b. That is, it flows in a direction parallel to the plate surface of the magnetic pole tooth piece 341 constituting the magnetic pole tooth block 34. The eddy current tends to flow in a direction that prevents the magnetic flux from changing on a plane perpendicular to the direction in which the magnetic flux flows. That is, as shown in FIG. 33, the magnetic flux tends to flow counterclockwise about the direction in which the magnetic flux flows. The direction of this eddy current is a direction that tries to penetrate the plate surface of the magnetic pole tooth piece 341 constituting the magnetic pole tooth block 34. However, since the magnetic pole tooth block 34 has a plurality of magnetic pole tooth pieces 341 stacked and the electric resistance between the magnetic pole tooth pieces 341 is increased, eddy current can be reduced. Furthermore, when an insulating coating is applied to the plate surface, the eddy current flowing between the magnetic pole tooth pieces 341 can be further reduced.

Furthermore, the height of the connection part 341b will be described. As shown in FIG. 33, let d be the height of the connecting portion 341b. Magnetic flux flowing between adjacent magnetic pole teeth 31 flows in the left-right direction on the paper. The path through which the magnetic flux flows is the shortest path. Therefore, the magnetic flux does not flow in a portion away from the magnetic pole teeth 31 by a certain distance or more. Therefore, the height d of the connecting portion 341b may be a value that allows a sufficient amount of magnetic flux in the left-right direction on the paper surface to flow. Further, the base portion 33 where the magnetic flux does not flow can be formed of a nonmagnetic material. For example, the base portion 33 is formed of alumina having a high rigidity and a high Young's modulus. Alternatively, nonmagnetic stainless steel or aluminum alloy can be used.

34A and 34B are graphs showing an example of Joule loss due to eddy current, and FIG. 34A is a graph showing Joule loss of the linear motor 1 in the basic example. FIG. 34A is a reproduction of FIG. 29B. FIG. 34B is a graph showing Joule loss of the linear motor 1 in the first modification. In the basic example, the magnetic pole teeth 31 have a laminated structure, whereas in the first modification, a part of the magnetic pole teeth and the base plate has a laminated structure. Other conditions, the structure and dimensions of the linear motor, the number of coil turns, and the driving conditions were the same. For example, the driving current of the coil is 70.6 A, and the moving speed of the mover is 1000 mm / s.

As shown in FIG. 34A, in the linear motor 1 in the basic example, the Joule loss of the back yoke 3 is around 50 W, whereas in the linear motor 1 in the first modification, as shown in FIG. 34B, the back yoke 3 joule loss is reduced to around 2.5W. This is because the connection part 341b has a laminated structure, and eddy currents due to magnetic flux flowing through the connection part 341b are also reduced. In FIGS. 34A and 34B, the graphs labeled U, V, and W indicate absolute values of Joule loss due to energization generated in the coil U phase, V phase, and W phase, respectively. In FIGS. 34A and 34B, the Joule loss in the coil due to energization of the coil is the same, but there is a large difference in the Joule loss in the back yoke. This result shows that the latter can reduce Joule loss due to eddy current when the magnetic pole teeth and the back yoke are partly laminated with the same dimension and shape. For example, the absolute value of Joule loss due to eddy current varies depending on the size of the linear motor and the speed of the linear motor, but the ratio of both effects at the same speed is maintained.

In the linear motor 1 in the first modification, the magnetic pole tooth block 34 is configured by laminating silicon steel plates (magnetic pole tooth pieces 341). In addition to the magnetic pole teeth 31, the linear motor 1 has a laminated structure in a part in the thickness direction from the connection portion with the magnetic pole teeth 31 of the back yoke 3. For this reason, the magnetic flux flowing between the adjacent magnetic pole teeth 31 to the connecting portion 341 b is in a direction parallel to the surface of the magnetic pole tooth piece 341. The direction of the eddy current generated by the flow of the magnetic flux is a direction to penetrate the plate surface of the magnetic pole piece 341. However, the electrical resistance in the eddy current direction in the connecting portion 341b is larger than that in the case of not having a laminated structure due to a gap on the surface of the magnetic pole tooth piece 341 or an oxide film formed on the surface. Therefore, it is possible to reduce the eddy current flowing through the connection portion 341b. Therefore, the eddy current flowing through the back yoke 3 can be further reduced.

Further, in the first modified example, in addition to the effects described above in Basic Example 1, the following effects are provided. Since the base portion 33 which is a part of the back yoke 3 can be formed of a nonmagnetic material, it can be formed of a material having a high Young's modulus, such as alumina. Thereby, since the rigidity of the entire back yoke 3 is increased, it is possible to reduce the bending due to the attractive force generated between the back yoke 3 and the mover 2. Furthermore, when the rigidity of the entire back yoke 3 is higher than the required rigidity of the base portion 33, the back yoke 3 can be made thinner.

(Second Modification of Embodiment 2)
The second modification relates to a form in which a part of the base plate 32 constituting the back yoke 3 has a laminated structure. FIG. 35 is a side view showing another configuration example of the back yoke 3. The back yoke 3 includes a plurality of back yoke units 301 and a back yoke unit 302. The back yoke unit 301 includes a base portion 35 and a magnetic pole tooth unit 36. The back yoke unit 302 includes a base portion 35 and a magnetic pole tooth unit 37. The difference between the back yoke unit 301 and the back yoke unit 302 is the difference between the magnetic pole tooth units included. One end of the back yoke 3 is a back yoke unit 301 and the other end is a back yoke unit 302. Thereby, as shown in FIG. 35, it is possible to constitute the back yoke 3 having the magnetic pole teeth 31 at both ends.

36A and 36B are perspective views showing a configuration example of the magnetic pole tooth units 36 and 37, FIG. 36A shows a configuration example of the magnetic pole tooth unit 36, and FIG. 36B shows a configuration example of the magnetic pole tooth unit 37. The magnetic pole tooth unit 36 includes a plurality of magnetic pole teeth 31 formed in a comb shape and a fitted portion 36a. The magnetic pole teeth 31 have a rectangular cross section. The fitted portion 36a has an inverted trapezoidal cross section.

The magnetic pole tooth unit 36 is formed by laminating a plurality of magnetic pole tooth pieces (plate-like members) 361. The stacking direction of the magnetic pole tooth pieces 361 is a direction crossing the arrangement direction of the magnetic pole teeth 31. The magnetic pole tooth piece 361 includes a fitted portion 361a, a connecting portion 361b, and a plurality of protruding portions 361c. The fitted portion 361a has an inverted trapezoidal cross section. The fitted portion 361 a is a portion that becomes the fitted portion 36 a of the magnetic pole tooth unit 36. The protrusion 361c has a rectangular cross section. The plurality of protrusions 361 c are formed at an equal pitch in the longitudinal direction of the magnetic pole piece 361. The protruding portion 361 c is a portion that becomes the magnetic pole teeth 31 of the magnetic pole tooth unit 36. The connecting portion 361b is a portion located between the fitted portion 361a and the protruding portion 361c in the height direction of the magnetic pole tooth piece 361. The connecting portion 361b connects the plurality of protruding portions 361c. The magnetic pole tooth piece 361 is made of, for example, a silicon steel plate. The connecting portion 361b is a plate-like member that constitutes a laminated portion that becomes a part of the base portion of the back yoke 3. The protruding portion 361 c is a plate-like member that constitutes the magnetic pole teeth 31. The magnetic pole tooth piece 361 is formed by integrating two plate-like members.

The magnetic pole tooth unit 37 is formed by laminating a plurality of magnetic pole tooth pieces 371. The stacking direction of the magnetic pole tooth pieces 371 is a direction intersecting the arrangement direction of the magnetic pole teeth 31. The magnetic pole tooth piece 371 has substantially the same configuration as the magnetic pole tooth piece 361. Hereinafter, the difference between the magnetic pole tooth pieces 371 and the magnetic pole tooth pieces 361 will be mainly described. The magnetic pole tooth piece 371 includes a fitted portion 371a, a connecting portion 371b, and a plurality of protruding portions 371c. The connection portion 361b of the magnetic pole tooth piece 361 protrudes in the longitudinal direction at one end portion in the longitudinal direction. On the other hand, the connecting portion 371b of the magnetic pole tooth piece 371 does not protrude in the longitudinal direction at both ends in the longitudinal direction. Since the other configuration of the magnetic pole tooth piece 371 is the same as that of the magnetic pole tooth piece 361, the description thereof is omitted.

FIG. 37 is a perspective view showing a configuration example of the base portion 35. The base part 35 shown in FIG. 37 is inverted upside down from the base part 35 shown in FIG. The base part 35 has a rectangular plate shape. The base portion 35 is formed with a fitting groove 35a having a trapezoidal cross section.

In the fitting groove 35a of the base portion 35, the fitted portion 36a of the magnetic pole tooth unit 36 or the fitted portion 37a of the magnetic pole tooth unit 37 is fitted. In the base portion 35, the length of the movable element 2 in the movable direction may be set according to the length of the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 in the movable direction. The base 35 and the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 are fixed as follows. After the adhesive is applied to one or both of the fitting groove 35a and the fitted portion 361a or the fitted portion 371a, the fitting is performed. Thereby, the base part 33 and the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 are fixed. As a result, the back yoke unit 301 or the back yoke unit 302 is formed. Then, by selecting the number of back yoke units 301 according to the stroke of the linear motor 1 and combining a plurality of back yoke units 301 and one back yoke unit 302, the back yoke 3 can be made as shown in FIG. It is formed. The respective back yoke units 301 and 302 may be coupled by a known method, for example, the back surfaces of the back yoke units 301 and 302 may be fixed by a rectangular plate member.

In the linear motor 1 in the second modification, the magnetic pole tooth units 36 and 37 are configured by laminating silicon steel plates (magnetic pole tooth pieces 361 and 371). In addition to the magnetic pole teeth 31, the linear motor 1 has a laminated structure in a part in the thickness direction from the connection portion with the magnetic pole teeth 31 of the back yoke 3. Therefore, the magnetic flux flowing between the adjacent magnetic pole teeth 31 to the connecting portions 361b and 371b is in a direction parallel to the surfaces of the magnetic pole tooth pieces 361 and 371. The direction of the eddy current generated by the flow of the magnetic flux is a direction to penetrate the plate surfaces of the magnetic pole tooth pieces 361 and 371. However, the electrical resistance in the eddy current direction in the connection portions 361b and 371b is larger than that in the case of not using the laminated structure due to the gap between the surfaces of the magnetic pole teeth 361 and 371 or the oxide film formed on the surface. . Therefore, it is possible to reduce eddy currents flowing through the connection portions 361b and 371b. Therefore, the eddy current flowing through the back yoke 3 can be further reduced.

In addition, in the second modified example, in addition to the effects described above in Basic Example 1, the following effects are provided. Since the base portion 35 which is a part of the back yoke 3 can be formed of a nonmagnetic material, it can be formed of a material having a high Young's modulus, such as alumina. Thereby, since the rigidity of the entire back yoke 3 is increased, it is possible to reduce the bending due to the attractive force generated between the back yoke 3 and the mover 2. Furthermore, when the rigidity of the back yoke 3 as a whole is higher than the rigidity required for the material of the base portion 35, the back yoke 3 can be made thinner. In the second modification, the stroke of the linear motor 1 can be changed by making the number of back yoke units 301 included in the back yoke 3 variable.

The back yoke units 301 and 302 each have five magnetic pole teeth 31, but the invention is not limited thereto. Although the base portion 33 includes one magnetic pole tooth unit 36 or magnetic pole tooth unit 37, the present invention is not limited thereto. The magnetic pole tooth unit 36 and the magnetic pole tooth unit 37 are each provided with the same number of magnetic pole teeth 31, but the present invention is not limited thereto.

(Third Modification of Embodiment 2)
The third modified example relates to a configuration in which the base portion 35 is a single plate in the second modified example. FIG. 38A is a side view showing another configuration example of the back yoke 3. The back yoke 3 includes a base portion 33, a plurality of magnetic pole tooth units 36 and a magnetic pole tooth unit 37. The configurations of the magnetic pole tooth unit 36 and the magnetic pole tooth unit 37 are the same as those of the second modified example described above, and thus the description thereof is omitted.

FIG. 38B is a perspective view showing a configuration example of the base portion 33. The base part 33 shown in FIG. 38B is upside down with respect to the base part 33 shown in FIG. 38A. The base portion 33 is formed with a plurality of dovetail grooves (fitting grooves) 33a in a rectangular plate material. The dovetail groove 33 a has a shape corresponding to the fitted portions 36 a and 37 a of the magnetic pole tooth units 36 and 37. The back yoke 3 is fixed to the dovetail groove 33a of the base portion 33 with the fitting portions 36a and 37a of the magnetic pole tooth units 36 and 37, and then fixed with an adhesive or the like. The base portion 33 is made of a nonmagnetic material.

In the third modified example, in addition to the effects described above in Basic Example 1, the following effects are provided. The base portion 33 which is a part of the back yoke 3 can be made of a nonmagnetic material having a high Young's modulus, such as alumina. Thereby, since the rigidity of the entire back yoke 3 is increased, it is possible to reduce the bending due to the attractive force generated between the back yoke 3 and the mover 2.

In the basic example and the first to third modifications described above, the gap between the adjacent magnetic pole teeth 31 may be filled with a nonmagnetic material such as a resin mold. Thereby, the strength of the back yoke 3 is increased, and the bending of the back yoke 3 due to the suction force generated between the movable body 2 and the back yoke 3 can be more effectively suppressed.

The base plate 32 in the basic example described above may have a laminated structure in a part opposite to the direction in which the magnetic pole teeth 31 protrude from the root portion of the magnetic pole teeth 31 (thickness direction). In other words, the magnetic pole teeth 31 (projections 31a and 31a) having a laminated structure may be engaged with the recesses 32a and 32a in the laminated structure portion of the base plate 32 having a partially laminated structure. Thereby, it becomes possible to suppress the eddy current by the magnetic flux which flows in the movable direction of the needle | mover 2 similarly to a 1st modification and a 2nd modification.

The technical features (components) described in each embodiment can be combined with each other, and a new technical feature can be formed by combining them. The embodiments disclosed herein are illustrative in all respects and should not be considered as restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Linear motor 2 Movable element 3 Back yoke 4 Armature 21 Permanent magnet 22 Holding frame 23 Fixed plate 31 Magnetic pole tooth 32 Base board 33 Base part 34 Magnetic pole tooth block 35 Base part 36 Magnetic pole tooth unit 37 Magnetic pole tooth unit 41 Core 42 Magnetic pole tooth 43 drive coil 221 hole 301 back yoke unit 302 back yoke unit 311 magnetic pole piece 341 magnetic pole tooth piece 361 magnetic pole tooth piece 371 magnetic pole tooth piece

Claims (9)

A mover having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged; a back yoke as a stator that is arranged opposite to the mover with a gap; and the back yoke with a gap in the mover Has an armature as a stator arranged opposite to the opposite side,
The magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the magnetization directions of adjacent permanent magnets are opposite to each other,
The armature has a plurality of magnetic pole teeth each having a drive coil wound at an equal pitch,
The back yoke has a plurality of magnetic pole teeth at the same position in the moving direction of the armature and the magnetic pole teeth of the armature on the surface facing the mover,
The magnetic pole area of the magnetic pole teeth in the back yoke is 0.9 to 1.1 times the magnetic pole area of the magnetic pole teeth in the armature, and the gap between the mover and the back yoke is the movable element and the back yoke. Linear motor characterized by being equal to or larger than the gap with the armature. 2. The linear motor according to claim 1, wherein the height of the magnetic pole teeth in the back yoke is not less than 1/20 times and not more than 2 times the pitch of the magnetic pole teeth. 3. The linear motor according to claim 1, wherein a length of the mover is shorter than a length of the armature and shorter than a length of the back yoke. 4. The size of the gap between the mover and the back yoke and / or the size of the gap between the mover and the armature are variable. The linear motor described in 1. A mover having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged; a back yoke as a stator that is arranged opposite to the mover with a gap; and the back yoke with a gap in the mover Has an armature as a stator arranged opposite to the opposite side,
The magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the magnetization directions of adjacent permanent magnets are opposite to each other,
The armature has a plurality of magnetic pole teeth each having a drive coil wound at an equal pitch,
The back yoke has a plurality of magnetic pole teeth at the same position in the moving direction of the armature and the magnetic pole teeth of the armature on the surface facing the mover,
The magnetic pole teeth of the back yoke are formed by laminating a plurality of plate-like members in a direction crossing the moving direction of the mover. The back yoke is formed by laminating a plurality of plate-like members in the stacking direction of the magnetic pole teeth, a part of the reverse direction of the direction in which the magnetic pole teeth protrude from the base part of the magnetic pole teeth,
The linear motor according to claim 5, wherein the plate-like member constituting the laminated portion of the back yoke and the plate-like member constituting the magnetic pole teeth are integrated. The linear motor according to claim 5, wherein the plurality of plate-like members are subjected to insulation treatment on a laminated surface. The mover includes a holding member that holds the magnet array, and the holding member includes a plurality of holes into which the plurality of permanent magnets are inserted. The linear motor according to any one of 1 to 7. The linear motor according to claim 8, wherein the mover has a plate-like base material to which the holding member and the plurality of permanent magnets are bonded and fixed.

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