JPWO2018174235A1 - Linear motor - Google Patents

Abstract

Abstract: Provided is a linear motor capable of significantly reducing a suction force and a detent force while achieving a small configuration and generating a large thrust. A linear motor has a movable element having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator arranged opposite to the movable element with a gap, and a back yoke with a gap in the movable element. An armature as a stator oppositely disposed on the opposite side, the magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the magnetization directions of the adjacent permanent magnets are opposite, Has a plurality of magnetic pole teeth each having a drive coil wound thereon at the same pitch, and the back yoke is located on the surface facing the mover at the same position as the magnetic pole teeth of the armature in the movable direction of the mover. Has a plurality of magnetic pole teeth.

Description

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

  Conventionally, a method of converting the output of a rotary motor into linear motion with a ball screw has been used for X and Y movement. However, since the moving speed is slow, a linear motor capable of directly extracting linear motion output is used. Usage is being promoted. A 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.

  Further, 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 having a small mass and a large acceleration. In order to reduce the size of such a linear motor, for example, as disclosed in Patent Literature 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 the permanent magnets in the armature is shorter than the armature length is employed.

  This type of linear motor includes a mover having a magnet arrangement in which a plurality of permanent magnets are arranged, a flat back yoke integrated with the magnet arrangement, and an armature in which a drive coil is wound around each of a plurality of magnetic pole teeth. Are opposed to 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 stroke at which the linear motor can operate.

  When the mover is composed of a back yoke made of a ferromagnetic material and a magnet array, an attractive force is generated between the stator and the opposing stator. Due to the generated attraction force, a large vertical reaction acts on a bearing that supports the mover so as to be movable in a predetermined direction. This normal drag results in a shortened bearing life. 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 vertical drag. Therefore, a larger bearing is selected than a bearing that conforms to the load imposed by the mover. This leads to an increase in the size of the entire linear motor.

  Therefore, unlike the above-described linear motors, 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 and the like).

  In this type of linear motor, the magnet arrangement and the flat back yoke are separated, and the back yoke is opposed to the magnet arrangement with a gap on the side opposite to the armature, so that only the magnet arrangement can be moved. Only the magnet arrangement 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 between the lengths is the operable stroke of the linear motor.

JP 2005-269822 A Re-published patent WO2016 / 159034 JP 2005-117856 A JP 2015-130754 A JP 2005-184984 A

The mover is strongly attracted to the magnetic pole tooth surfaces of the opposed armature. The suction force F at this time is represented by the following equation.
F = B ² S / 2μ ₀
(However, B: magnetic flux density on the magnetic pole teeth of the electrode, S: effective area facing the mover and the armature, μ ₀ : magnetic permeability in 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 or the like), the attractive force is usually several times to ten times or more the rated thrust. Becomes Therefore, there is a problem that the mover bends due to 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 drawback that the configuration is increased in size.

  Excessive suction force is also exerted on the linear guide that supports the mover, so the linear guide must have a large rated load to withstand this excessive suction force. I can't. Therefore, it is desired to reduce the above-mentioned suction force. However, when reducing the suction force, it is necessary to be able to realize both the small configuration and the generation of a large thrust.

  Further, 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 having a configuration in which a magnet array and a flat back yoke are separated to move only the magnet array (separable linear motors: Patent Documents 3 to 5 and the like), the magnet array has a back yoke and an armature. Therefore, the overall 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 magnetic pole teeth facing the armature side, while the area of all magnets on the back yoke side is almost the same. Therefore, when the magnetic flux densities in both gaps are the same, a larger attractive force acts on the back yoke side according to the ratio of the magnetic pole areas, so that the overall attractive force is greatly reduced. Can not hope.

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

  Further, in the separation type linear motor, as described above, the attraction force between the mover (magnet arrangement) and the stator (armature) and the attraction force between the mover and the back yoke have substantially the same magnitude. , The suction force acting on the mover can be reduced. However, it became clear that the eddy current generated in the back yoke during operation increased due to the separation of 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 device that needs to maintain an environmental temperature within a predetermined range, for example, a stage driving source in a semiconductor manufacturing device.

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

  It is another object of the present invention to provide a linear motor capable of suppressing an eddy current while reducing an attractive force acting on a magnet array.

  The 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 disposed to face the mover with a gap, and a movable yoke. An armature as a stator disposed opposite to the back yoke with a gap therebetween, wherein the magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the permanent magnets The magnetization direction is opposite, the armature has a plurality of magnetic pole teeth each having a drive coil wound thereon at an equal pitch, and the back yoke is provided on a surface facing the mover, The armature has a plurality of magnetic pole teeth at the same position in the moving direction of the armature as the magnetic pole teeth, 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. 0.9 to 1.1 times The gap between the movable element and said back yoke, characterized by equal to or greater the gap between the mover and the armature.

  In the linear motor of the present invention, a mover having a magnet array in which a plurality of permanent magnets are arranged, a back yoke arranged to face the mover with a gap, and a gap on the side opposite to the back yoke An armature facing the mover. The magnet arrangement functions as a mover, and the back yoke and the 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 direction is opposite between adjacent permanent magnets. The armature has a plurality of magnetic pole teeth at an equal pitch, and a drive coil is wound around 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 on the back yoke is equal to the pitch of the magnetic pole teeth of the armature, and the position of the magnetic pole teeth on the back yoke is the same 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. The gap between the mover and the back yoke is equal to or larger 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 a gap from the mover is provided in a portion other than 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 to each other, they are effectively canceled each other, and the overall attractive force is significantly reduced. Therefore, the suction force can be significantly reduced without increasing the gap between the mover and the back yoke. At this time, since there is no need to increase the gap between the mover and the back yoke, the reduction in thrust is small.

  Further, a shearing region of the drive 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, so that not only the armature but also the back yoke contributes to the generation of thrust. The generation of this thrust compensates for the decrease in thrust caused by the increase in the gap (air gap) with the mover at two locations, and a large thrust as a whole is obtained. Therefore, the attractive force acting on the magnet arrangement (movable element) can be significantly reduced while maintaining a large thrust.

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

  If the magnetic pole area of the magnetic pole teeth of the back yoke is too large, a large amount of magnetic flux is picked up from the surroundings to increase the attractive force, while if the magnetic pole area of the magnetic pole teeth of the back yoke is too small, thrust is obtained. 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 around the magnetic pole teeth of the armature, the magnetic pole teeth of the armature are not configured so low, and the height of the magnetic pole teeth of the armature is higher than the height of the magnetic pole teeth of the back yoke. For this reason, in the back yoke, since the height of the magnetic pole teeth is low, a magnetic flux is generated also 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 effectively canceled.

  The linear motor according to the present invention is characterized in that the height of the magnetic pole teeth on the back yoke is 1/20 to 2 times the pitch of the magnetic pole teeth.

  In the linear motor of the present invention, if the height of the magnetic pole teeth of the back yoke is too small compared to the pitch, the effect of providing the magnetic pole teeth (uneven shape) cannot be obtained. If the height is too large compared to the pitch, the effect is not changed and the miniaturization is reversed. Therefore, the height of the magnetic pole teeth on the back yoke is set to be not less than 1/20 times and not more than twice 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, the configuration is small, 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 according to 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 are 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 during use, the attraction force can be reduced to almost zero. It is possible to

  The 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 disposed to face the mover with a gap, and a movable yoke. An armature as a stator disposed opposite to the back yoke with a gap therebetween, wherein the magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the permanent magnets The magnetization direction is opposite, the armature has a plurality of magnetic pole teeth each having a drive coil wound thereon at an equal pitch, and the back yoke is provided on a surface facing the mover, The magnetic pole teeth of the armature and the moving direction of the mover have a plurality of magnetic pole teeth at the same position, and the magnetic pole teeth of the back yoke move a plurality of plate-shaped members in the moving direction of the mover. Layered in the direction that intersects The features.

  In the linear motor according to the present invention, by forming the magnetic pole teeth in a laminated structure, it is possible to reduce the eddy current while reducing the attraction force acting on the mover.

  In the linear motor according to the present invention, in the back yoke, a part of a direction opposite to a direction in which the magnetic pole teeth protrude from a root portion of the magnetic pole teeth is formed by stacking a plurality of plate members in a stacking direction of the magnetic pole teeth. The plate member forming the laminated portion of the back yoke and the plate member forming the magnetic pole teeth are integrated with each other.

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

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

  In the linear motor according to the present invention, since the plurality of plate-shaped members are subjected to the 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 that holds 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 the following.

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

  The linear motor according to the present invention is characterized in that the mover has a plate-shaped 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 arrangement (the plurality of permanent magnets) and the holding member are bonded and fixed to the plate-shaped base member in a state where the plurality of 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.

  ADVANTAGE OF THE INVENTION In the linear motor of this invention, the attraction force which acts on a mover (magnet arrangement | sequence) can be reduced sharply, and the detent force of a mover is reduced, realizing a small structure and large generation of a thrust. Can be. Therefore, deformation due to bending caused by a large suction force can be suppressed, and deterioration of dimensional accuracy of a device using a linear motor can be prevented. Since the suction force can be reduced, the rigidity of the mover and the rigidity of the support system for supporting the mover can be reduced, so that not only the size can be reduced, but also the acceleration can be improved by reducing the weight of the movable mass. In addition, since the thrust from the back yoke is added to the mover by providing the magnetic pole tooth structure on the back yoke, the reduction in thrust due to the provision of a gap between the magnet arrangement and the back yoke is minimized. be able to.

  Further, in the linear motor of the present invention, it is possible to suppress the eddy current while reducing the attraction force acting on the mover (magnet arrangement).

FIG. 2 is a perspective view illustrating a configuration of the linear motor according to the first embodiment. FIG. 2 is a side view illustrating a configuration of the linear motor according to the first embodiment. FIG. 3 is a plan view showing a configuration of a mover in the linear motor according to the first embodiment. FIG. 2 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 illustrating a flow of a 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. FIG. 3 is a plan view showing an armature material used for manufacturing an armature in the linear motor according to the first embodiment. FIG. 3 is a diagram showing windings of an armature in the linear motor according to the first embodiment. FIG. 2 is a top view illustrating a configuration of the linear motor according to the first embodiment. FIG. 2 is a side view illustrating a configuration of the linear motor according to the first embodiment. 4 is a graph illustrating a thrust variation with respect to an electrical angle of a linear motor according to an example of the first embodiment; 4 is a graph illustrating a thrust characteristic of the linear motor according to one example of the first embodiment; 5 is a graph showing a suction force characteristic of the linear motor according to the first embodiment; FIG. 6 is a side view showing a configuration of a linear motor of a first conventional example (a configuration in which a magnet arrangement and a back yoke are integrated to form a 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 a 2nd conventional example (The structure which used only the magnet arrangement as a mover and the flat-plate-shaped back yoke as a stator). It is a top view which shows the structure of the linear motor of a 2nd conventional example. It is a side view showing the composition of the linear motor of the 2nd conventional example. 5 is a graph showing an average thrust in the linear motor according to the first conventional example, the second conventional example, and the example of the first embodiment. 6 is a graph showing an average suction force of the linear motor according to the first conventional example, the second conventional example, and the example of the first embodiment; 6 is a graph showing thrust characteristics of a linear motor according to another example of the first embodiment. 9 is a graph showing a suction force characteristic of a linear motor according to another example of the first embodiment. 7 is a graph illustrating a thrust characteristic of a linear motor according to still another example of the first embodiment. 9 is a graph illustrating a suction force characteristic of a linear motor according to still another example of the first embodiment. FIG. 9 is a perspective view illustrating a configuration example of a linear motor according to a second embodiment. FIG. 10 is a side view illustrating a configuration example of a linear motor according to a second embodiment. FIG. 4 is a perspective view illustrating a configuration example of magnetic pole teeth included in a back yoke. FIG. 4 is a partial perspective view illustrating a configuration example of a base plate included in a back yoke. It is a partial perspective view of a back yoke. It is a partial side view of a linear motor. 6 is a graph showing Joule loss of a linear motor according to a related technique. 14 is a graph showing Joule loss of a linear motor in a basic example of Embodiment 2. It is a side view which shows the other example of a structure of a back yoke. It is a perspective view which shows the example of a structure of a magnetic pole tooth block. FIG. 4 is a perspective view illustrating a configuration example of a base unit. It is a partial side view of a linear motor. 14 is a graph showing Joule loss of a linear motor in a basic example of Embodiment 2. 14 is a graph showing Joule loss of a linear motor according to a first modification of the second embodiment. It is a side view which shows the other example of a structure of a back yoke. It is a perspective view which shows the example of a structure of a magnetic pole tooth unit. It is a perspective view which shows the example of a structure of a magnetic pole tooth unit. FIG. 4 is a perspective view illustrating a configuration example of a base unit. It is a side view which shows the other example of a structure of a back yoke. FIG. 4 is a perspective view illustrating a configuration example of a base unit.

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

(Embodiment 1)
1 and 2 are a perspective view and a side view showing the configuration of the linear motor 1 according to 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 according to the first embodiment. 1 and 2, only the mover 2 shows 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 arranged facing the movable element 2 with a gap, and an armature 4 is arranged facing the opposite side of the movable element 2 from the back yoke 3 with a gap. The back yoke 3 and the armature 4 function as a stator.

  As shown in FIG. 4, the mover 2 having a long shape includes a plurality of permanent magnets 21, a holding frame 22, and a fixed plate 23. 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, an Nd—Fe—B-based 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 magnets 21 magnetized in the direction from the back yoke 3 side to the armature 4 side and the permanent magnets 21 magnetized in the direction from the armature 4 side to the back yoke 3 side alternately. Are located.

  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 non-magnetic material such as SUS or aluminum. The hole 221 has a shape corresponding to the permanent magnet 21. Each permanent magnet 21 is fitted in 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. When fixing the permanent magnets 21 to the holding frame 22, the permanent magnets 21 are fitted into the holes 221 such that the magnetization directions of the adjacent permanent magnets 21 are opposite to each other. As shown in FIG. 3, each of the permanent magnets 21 is skewed at an angle θ.

  The holding frame 22 is fixed to the fixing plate 23 with an adhesive in a state where the plurality of permanent magnets 21 are inserted and held in the holes 221 of the holding frame 22. Further, the bottom surface of each permanent magnet 21 is also adhered to the fixed plate 23. The fixed plate 23 is made of non-magnetic SUS or the like. As described above, since the magnet arrangement is held by the holding frame 22 and fixedly adhered to the fixed plate 23, the rigidity of the mover 2 is high, and the permanent magnet 21 does not fall off. The mover 2 is arranged in the gap between the back yoke 3 and the armature 4 such that the fixed plate 23 faces the back yoke 3. Note that the fixing plate 23 is not essential, and is unnecessary 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 (horizontal direction in FIG. 2) are substantially equal, and the length of the mover 2 in the movable direction (horizontal direction in FIG. 2) is equal to the length of the back yoke 3 and the armature. The length of the linear motor 1 is shorter than the length of the linear motor 1. With such a configuration, the edge effect is reduced.

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

  In the armature 4, a plurality of rectangular magnetic pole teeth 42 made of a soft magnetic material are integrally provided at a constant pitch in the movable direction on a core 41 made of a soft magnetic material. 43 is turned.

  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 position of each magnetic pole tooth 31 in the back yoke 3 is Is the same as the position. The shape of the magnetic pole face of the magnetic pole teeth 31 of the back yoke 3 facing the mover 2 is substantially the same as the shape of 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 times to 1.1 times the latter magnetic pole area. For example, the magnetic pole surface of the magnetic pole teeth 31 and the magnetic pole surface of the magnetic pole teeth 42 have the same rectangular shape and the same area. The gap between the mover 2 and the back yoke 3 is equal to 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. In this case, the gap between the mover 2 and the back yoke 3 does not include the thickness of the fixed plate 23 even when the fixed plate 23 is included as a component, and the gap between the mover 2 itself and the back yoke 3 (the shortest). Distance). In other words, this gap is a magnetic gap (magnetic gap), and there is no need to consider the thickness of the fixed plate 23 which 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 and six magnetic pole teeth 31 and magnetic pole teeth 42 face each other. The embodiment shown in FIGS. 1 and 2 has a 14-pole, 12-slot configuration which is twice the basic configuration.

  In the linear motor 1 of the first embodiment, the surface of the back yoke 3 facing the mover 2 has a magnetic pole surface of substantially the same shape as the magnetic pole teeth 42 of the armature 4 at the same position in the movable direction. Magnetic pole teeth 31 having substantially the same magnetic pole area are formed. Therefore, the magnitude of the attraction force generated between the mover 2 and the back yoke 3 is substantially equal to the magnitude of the attraction force generated between the mover 2 and the armature 4, and both suction forces are in the vertical direction in FIG. Are effectively canceled out, the suction force acting on the mover 2 as a whole of the linear motor 1 becomes very small. As described above, in the linear motor 1 according to the first embodiment, a large reduction in suction force can be realized 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 does not decrease.

  Further, in the linear motor 1 according to the first embodiment, as described above, the armature 4 having the plurality of magnetic pole teeth 42 at the same pitch, and the plurality of the magnetic pole teeth 42 of the armature 4 at the same position in the movable direction. And the back yoke 3 having the magnetic pole teeth 31, the cogging torque of the magnet arrangement in the direction perpendicular to the moving direction is reduced. Reduction can be achieved. Furthermore, since the magnet array is held by the holding frame 22 and fixed to the fixed plate 23 by adhesion, the rigidity of the mover 2 can be increased, so that the permanent magnet 21 is hardly deformed such as bending or bending. However, this contributes to a reduction in the detent force of the mover 2.

  In the linear motor 1 according to the first embodiment, a plurality of magnetic pole teeth 31 are formed on the back yoke 3, and a shearing region of the drive magnetic flux is generated by the uneven 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 according to the first embodiment. In FIG. 5, arrows indicate the flow of magnetic flux. In the linear motor 1, a thrust is generated by the shearing of the magnetic flux on the armature 4 side, and a thrust is also generated by the shearing of the magnetic flux on the back yoke 3 side. Is the sum of 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 the magnetic flux shearing on the armature side. Becomes

  In the linear motor 1 according to 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 may be reduced by the gap. However, since the thrust can be generated on the back yoke 3 side as described above, a large thrust can be realized by compensating for a 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 significantly reduced while maintaining a large thrust. Accordingly, the movable element 2 hardly bends due to the suction force, and the dimensional accuracy of a processing machine in a semiconductor manufacturing apparatus using the linear motor 1 becomes extremely high.

  Further, in the linear motor 1 according to the first embodiment, since the attraction force can be reduced, no problem occurs 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 weight of the mover 2 is reduced. Also, since the wear of the mover 2 is small, the life of the linear motor 1 can be extended.

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

  In the linear motor 1 according to the first embodiment, the length of the mover 2 is 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 inventor and characteristics of the manufactured linear motor 1 will be described.

First, the mover 2 was manufactured. Nd-Fe-B based rare earth magnet _{(B r = 1.395T, H cJ} = 1273kA / m) from the block, a thickness of 5 mm, a width 12 mm, was cut out a rectangular fourteen permanent magnets 21 of length 82mm . 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 from a SUS plate having a thickness of 3 mm by wire cutting. The cut-out holding frame 22 was bonded and fixed to a fixing plate 23 made of a SUS plate having a thickness of 0.2 mm. Then, the skew angle θ = 3.2 ° is applied to the 14 permanent magnets 21 coated with the 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 bonded 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 to 5 mm so as to achieve both the weight reduction of the mover 2 and the high rigidity of the magnet arrangement.

  In addition, unlike the above-described example, the holding frame 22 may be manufactured by a method in which six SUS sheets each having a hole formed by press working on a 0.5 mm thick SUS plate are stacked and fixed by caulking. good. In this case, the manufacturing cost can be reduced.

  Next, the back yoke 3 was produced. FIG. 6 is a diagram illustrating 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), and 18 magnetic pole teeth 31 of the same shape (width: 6 mm, height: 3 mm, length: 82 mm, The back yoke 3 having a magnetic pole area of 492 mm ² ) at an equal pitch (15.12 mm) was manufactured.

Next, the armature 4 was manufactured. FIG. 7 is a plan view showing an armature material used for manufacturing the armature 4 in the linear motor 1 according to the first embodiment. The armature material 44 having a shape as shown in FIG. 7 is cut out from a silicon steel sheet (JIS standard C2552, type code 50A800) having a thickness of 0.5 mm, 164 sheets are cut out, and the cut out 164 sheets are piled up and the side surface is irradiated with CO ₂ laser. After melting and integrating, a block body having a width of 82 mm, a height of 31 mm, and a length of 263.04 mm (18 magnetic pole teeth 42 having the same shape on the core 41 (width: 6 mm, height: 25 mm, length: 82 mm, magnetic pole) (Structure having an area of 492 mm ² ) at an equal pitch (15.12 mm)).

  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. The armature of each magnetic pole tooth 42 of the armature 4 was wound with an enamel-coated lead wire having a diameter of 2 mm 17 times and impregnated with varnish and fixed to form a drive coil 43.

  In FIG. 8, U, V, and W indicate the U, V, and W phases of the three-phase AC power supply, respectively, and the coils of each phase are all connected in series. The U coil, V coil, and W coil are connected so that current flows clockwise when viewed from above, and the -U coil, -V coil, and -W coil are connected such that current flows counterclockwise when viewed from above. Thus, an armature 4 was manufactured. Then, six U-coils, -U-coils, V-coils, -V-coils, W-coils, and -W-coils were star-connected, and connected to a three-phase AC power supply.

  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 was fixed to be 6 mm, the gap was configured to be adjustable after assembling the linear motor 1. Next, after attaching a linear guide (not shown) to the side surface of the mover 2, the gap between the back yoke 3 and the armature 4 is separated by a predetermined distance from the back yoke 3 and the armature 4 to a thickness of 5 mm. The linear motor 1 was manufactured by inserting the mover 2 of FIG. At this time, the distance between the magnetic pole teeth 31 of the mover 2 and the back yoke 3 and the distance between the magnetic pole teeth 42 of the armature 4 and the armature 4 were both set to 0.5 mm. 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 movable element 2 and the back yoke 3 (with the distance between the movable element 2 and the armature 4 (magnetic pole teeth 42) kept constant. The distance between the magnetic pole teeth 31) and the gap can be set arbitrarily and made variable. 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 (magnetic pole teeth 31), and the distance between the mover 2 and the It is also possible to set the ratio of the distance of the gap with the child 4 (magnetic pole teeth 42) to a desired value.

  In addition, as a mechanism for adjusting the gap between the armature 4 and the linear guide supporting 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 sectional shape A mechanism for adjusting the height by inserting a shim plate having a tapered shape with screws can be adopted.

  9A and 9B are diagrams showing a configuration of the linear motor 1 according to the 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, open arrows indicate the magnetization direction of the permanent magnet 21, and solid arrows indicate the movable direction of the mover 2. The details of the manufacturing specifications of the linear motor 1 are as follows.

Magnetic pole configuration: 7 poles 6 slots Material of permanent magnet 21: Nd-Fe-B based rare earth magnet (NMX manufactured by Hitachi Metals, Ltd.)
-S49CH material)
Shape of permanent magnet 21: thickness 5.0 mm, width 12 mm, length 82 mm
Pitch of permanent magnet 21: 12.96 mm
Skew angle of permanent magnet 21: 3.2 °
Back yoke 3 shape: thickness 6.0 mm, width 90 mm, length 263.04 mm
Back yoke 3 material: Mild steel (JIS standard G3101 type code SS400)
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 the core 41: silicon steel plate (JIS standard C2552, type code 50A800)
Shape of magnetic pole teeth 42: width 6.0 mm, height: 25 mm, length: 82 mm
Pitch of magnetic pole teeth 42: 15.12 mm
Shape of drive coil 43: width 15.12 mm, height 23 mm, length 91.12 mm
The winding thickness of the drive coil 43: 4.06 mm
Diameter and number of windings of the driving coil 43: 2 mm in diameter, 17 turns Winding resistance (1 piece): 0.0189Ω
Mass of the mover 2: 516.6 g

  In the linear motor 1 described above, the length of the mover 2 (190 mm) is shorter than the length 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 both 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 pole face of the magnetic pole tooth 31 facing the magnet arrangement and the shape of the magnetic pole face of the magnetic pole tooth 42 facing the magnet arrangement are rectangular shapes having the same dimensions. That is, the width (the dimension in the movable direction) of the magnetic pole teeth 31 and the width (the dimension in the movable direction) of the magnetic pole teeth 42 are both equal to 6 mm, and are equal to the pole area and the magnet arrangement of the magnetic pole teeth 31 facing the magnet arrangement. The magnetic pole areas of the magnetic pole teeth 42 facing each other are 492 mm ² and are equal.

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

  FIG. 10 is a graph showing a change in thrust with respect to an electrical angle of the linear motor 1 according to the example of the first embodiment. This thrust variation is caused by the thrust (the three-phase combined thrust of U-phase, V-phase, and W-phase) with respect to the position of the mover 2 when the drive magnetomotive force (= the magnitude of the drive current × the number of turns of the drive coil 43) is 1200 A. Represents the change. In FIG. 10, the horizontal axis is the electrical angle [°], and the vertical axis is the thrust [N]. In the figure, a represents the thrust by the armature 4, b represents the thrust by the back yoke 3, and c represents the total thrust (the added thrust of the thrust by the armature 4 and the thrust by the back yoke 3). I have. 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 according to the example of the first embodiment. The thrust characteristics represent characteristics when the current applied to the drive coil 43 is changed. In FIG. 11, the horizontal axis represents the driving magnetomotive force [A], the left vertical axis represents the thrust [N], and the right vertical axis represents the thrust magnetomotive force ratio [N / A]. Further, a in the figure represents the thrust, and b in the figure represents the thrust magnetomotive force ratio. In this linear motor 1, the thrust proportional limit (the thrust magnetomotive force ratio is reduced by 10%) is 1000N when the driving magnetomotive force is 1200A.

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

  By the way, in order to evaluate the linear motor 1 of the first embodiment in comparison with a conventional linear motor, two types of linear motors (a first conventional example and a second conventional example) are manufactured as a conventional example, and those linear motors are manufactured. The characteristics (thrust and suction) 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 has a mover 51 in which a magnet array 52 and a back yoke 53 are integrated, and an armature 54 that is opposed to the mover 51 with a gap. In the first conventional example, a structure in which the magnet arrangement 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 a plurality of rectangular permanent magnets 55 at a constant pitch on a holding frame made of a non-magnetic material and installing the permanent magnets 55 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 are opposite to each other. In the linear motor 50 of the first conventional example, the magnet arrangement 52 is bonded to a flat 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 a constant pitch in the movable direction. The drive coil 58 is wound.

  14A and 14B are views showing the configuration of such a 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, open arrows indicate the magnetization direction of the permanent magnet 55, and solid arrows indicate the movable direction of the mover 51. The size of the gap between the mover 51 and the armature 54 was 0.5 mm or 1 mm. The details of the manufacturing specifications of the linear motor 50 are as follows.

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

  The length of the mover 51 (integrated configuration of the magnet arrangement 52 and the back yoke 53) in the movable direction (the left-right direction in FIG. 13) is shorter than the length of the armature 54. 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 (separable linear motor) having a configuration according to Patent Documents 3 to 6. In FIG. 15, only the magnet arrangement 62 shows 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 facing the magnet array 62 with a gap, and a facing yoke 63 opposite to the back yoke 63 with a gap in the magnet array 62. And an armature 64. Only the magnet arrangement 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 holding a plurality of rectangular permanent magnets 65 at a constant pitch on a non-magnetic material holding frame and installing the permanent magnets 65 in the movable direction (the left-right direction in FIG. 15). The magnet 65 is magnetized in the thickness direction (vertical direction in FIG. 15), and the magnetizing directions of the adjacent permanent magnets 65 are opposite to each other. The back yoke 63 made of mild steel has not only the surface on the side not facing the magnet array 62 but also the surface on the side facing the magnet array 62 having a flat plate shape, and has 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 a constant pitch in the movable direction. The drive coil 68 is wound.

  16A and 16B are diagrams showing the configuration of such a second conventional linear motor 60, FIG. 16A is a top view thereof, and FIG. 16B is a side view thereof. In FIG. 16B, open arrows represent the magnetization direction of the permanent magnet 65, and solid arrows represent the movable direction of the magnet array 62 (movable element). 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. The details of the manufacturing specifications of the linear motor 60 are as follows.

Magnetic pole configuration: 7 poles 6 slots Material of permanent magnet 65: Nd-Fe-B based rare earth magnet (NMX manufactured by Hitachi Metals, Ltd.)
-S49CH material)
Shape of permanent magnet 65: thickness 5.0 mm, width 12 mm, length 82 mm
Pitch of permanent magnet 65: 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 code SS400)
Core 66 physique: height 31mm, width 82mm, length 263.04mm
Material of the core 66: silicon steel plate (JIS standard C2552, type code 50A800)
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
Shape of drive coil 68: width 15.12 mm, height 23 mm, length 91.12 mm
The winding thickness of the drive coil 68: 4.06 mm
Diameter and number of windings of the driving coil 68: number of turns: 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 (the left-right direction in FIG. 15) is shorter than the length of the armature 64, and the difference in this length is the stroke in which the linear motor 60 can operate.

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

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

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

  In the linear motor 50A (A in the figure) of the first conventional example, the thrust is the largest and is 1030N, but the suction force is 4200N, which is about four times as large as the thrust. In the linear motor 50B (B in the figure) as a measure to reduce the suction force, the obtained thrust is significantly reduced to 909N, whereas the suction force is not significantly reduced to 3360N. Therefore, it is understood that sufficient measures have not been taken.

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

  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 significantly reduced to 290N (about 1/14 of the linear motor 50A) on the back yoke 3 side. Therefore, it has been proved that the linear motor 1 according to the example of the first embodiment can greatly reduce the suction force 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 attraction force changes according to 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 according to the thrust area (drive magnetomotive force) that is often used, the attraction 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 all equal to 0.5 mm. In the example, the gap between the mover 2 and the back yoke 3 was 0.74 mm while the gap between the mover 2 and the armature 4 was kept at 0.5 mm. The other configuration is the same as the above-described example.

  FIG. 19 is a graph showing the thrust characteristics of another example of the linear motor 1 of the first embodiment, and FIG. 20 is a graph showing the attraction force characteristics of the linear motor 1 of another example of the first embodiment. . In FIG. 19, the horizontal axis is the driving magnetomotive force [A], the left vertical axis is the thrust [N], the right vertical axis is 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 is the driving magnetomotive force [A], and the vertical axis is the attraction force [N].

  In another example, when the driving magnetomotive force is 1200 A, the thrust is 978 N, which is a little lower than in the above-described example. However, when the driving magnetomotive force is 1200 A, the thrust is only 18 N and almost zero. Has been realized. This is a suction force at a level at which deformation and reduction in life of the linear guide, the mover, and peripheral structures due to the suction force can be ignored. Therefore, when using the driving magnetomotive force near 1200 A, it is understood that the linear motor 1 of another example is more suitable for the purpose of reducing the attraction force than the above-described example.

  Further, as still another example of the first embodiment, a linear motor 1 in which the gap between the mover 2 and the back yoke 3 is 0.66 mm while the gap between the mover 2 and the armature 4 remains 0.5 mm. Was prepared. The other configuration is the same as the above-described example.

  FIG. 21 is a graph illustrating a thrust characteristic of a linear motor 1 according to still another example of the first embodiment. FIG. 22 is a graph illustrating an attraction force characteristic of the linear motor 1 according to still another example of the first embodiment. It is. In FIG. 21, the horizontal axis is the driving magnetomotive force [A], the left vertical axis is the thrust [N], the right vertical axis is 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 is the driving magnetomotive force [A], and the vertical axis is the attraction force [N].

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

  From the above, by appropriately setting the size of the gap between the mover 2 and the back yoke 3 in accordance with the frequently used area, the suction force can be significantly reduced and almost zero can be achieved. . As a result, it is possible to prevent the dimensional accuracy from deteriorating due to the bending of the mover 2 (magnet arrangement) and to shorten the life due to an excessive load on the linear guide.

  In the above-described embodiment, an 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. An example in which the size of the gap between the mover 2 and the back yoke 3 is fixed and the size of the gap between the mover 2 and the armature 4 is changed, such as 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 the position.

  Further, in the above-described embodiment, the linear motor 1 in which the mover 2 is shorter than the armature 4 has been described. On the contrary, the present invention also applies to a linear motor in which the mover is longer than the armature. (The magnetic pole teeth are formed 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 according to the second embodiment. 23 and 24, only the mover 2 shows 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 according to the second embodiment includes the mover 2, the back yoke 3, and the armature 4 as in the first embodiment, and the back yoke 3 and the armature 4 function as stators.

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

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

  The back yoke 3 and the armature 4 are opposed to each other with a gap therebetween. Then, the mover 2 is arranged in the gap. The first surface of the mover 2 faces the back yoke 3 with a gap. A 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 (the horizontal 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 position of each magnetic pole tooth 31 in the back yoke 3 is the same as the position of each magnetic pole tooth 42 of the armature 4 in the moving direction of the mover 2. The magnetic pole surface of the magnetic pole teeth 31 and the magnetic pole surface of the magnetic pole teeth 42 have the same rectangular shape and the same area. The gap between the mover 2 and the back yoke 3 is almost 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, 21 are opposite. When the mover 2 is disposed 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 In this configuration, the permanent magnets 21 magnetized in the directions are alternately arranged.

  When the linear motor 1 operates, 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. Further, an attractive force is also generated between the magnetic pole teeth 42 of the armature 4 and the permanent magnets 21 of the mover 2. The 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 teeth 31 and the magnetic pole surface of the magnetic pole teeth 42 have the same rectangular shape and the same area, the magnitude of the attraction 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 cancel each other. If it is difficult to balance the two attractive forces due to factors such as processing errors and assembly errors, adjust 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. 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 above-described first embodiment. Like the linear motor 1 of the first embodiment, the suction force acting on the mover 2 can be significantly reduced while maintaining a large thrust. Further, in the linear motor 1 according to the second embodiment, similarly to the linear motor 1 according to the first embodiment, the detent force of the mover 2 can be reduced.

  Hereinafter, the configuration of the back yoke 3 which is a feature of the second embodiment will be described in detail. FIG. 25 is a perspective view showing a configuration example of the magnetic pole teeth 31 included in the back yoke 3. The magnetic pole teeth 31 have a T-shaped cross section, and have two protruding portions 31a, 31a protruding in the lateral direction from the bottom (the lower side in FIG. 25). (Therefore, in FIG. 25, the H-shape is formed horizontally.) The protruding portions 31a, 31a are portions to be engaged with concave portions 32a, 32a of the dovetail 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 stacking magnetic pole pieces 311. The pole piece 311 includes an engagement protrusion 311a formed by cutting out a part of a rectangular plate shape. The pole piece 311 is formed of a thin plate of soft magnetic silicon steel or the like. The stacked magnetic pole pieces 311 are fixed to each other by heat welding or caulking. In the case of heat welding, for example, first, a thermosetting adhesive is applied to the surface of the pole piece 311 or a material having a heat-welding coating film is laminated, and then heated while applying pressure to the plate surface. . The pole pieces 311 are fixed to each other by heating.

  The eddy current loss decreases as the thickness of the pole piece 311 constituting the pole teeth 31 decreases, that is, as the number of the pole pieces 311 increases. In consideration of the strength and the labor of assembling, the thickness of the pole piece 311 is desirably 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. 26 is drawn upside down from FIGS. 24 and 25 for convenience of explanation. The base plate 32 is provided with a dovetail groove 321 along the lateral direction. The dovetail groove 321 has a shape corresponding to the protrusion 311a of the magnetic pole piece 311 (the protrusion 31a of the magnetic pole teeth 31). The dovetail groove 321 has a concave portion 32a corresponding to the projection 311a (projection 31a). As shown in FIGS. 24 and 25, a plurality of dovetail grooves 321 are formed in the base plate 32. 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 operates.

  FIG. 27 is a partial perspective view of the back yoke 3. As in FIG. 26, for convenience of description, the drawing is drawn upside down from FIGS. 24 and 25. In the back yoke 3, the protrusion 31 a of the magnetic pole tooth 31 is engaged with the dovetail groove 321.

  The magnetic pole teeth 31 are fixed to the base plate 32, for example, as follows. An adhesive is applied to one or both of the dovetail groove 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 has hardened, 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 so as to be within a predetermined error range.

  The linear motor 1 generates a magnetic flux flowing 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. I do. The attraction force generated between the mover 2 and the armature 4 due to 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, 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 the magnetic flux is indicated by a solid arrow, and an example of the eddy current is indicated by a dotted 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, the magnetic flux flows in a direction parallel to the plate surface of the magnetic pole piece 311 constituting the magnetic pole teeth 31. The eddy current tends to flow in a direction that prevents a change in the magnetic flux on a plane perpendicular to the direction in which the magnetic flux flows. That is, in the case shown in FIG. 28, the magnetic flux tends to flow counterclockwise at right angles to the direction in which the magnetic flux flows. The direction of the eddy current is a direction that is going to penetrate the plate surface of the pole piece 311 constituting the magnetic pole teeth 31. However, since 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, eddy current can be reduced. Further, when an insulating coating is applied to the plate surface (front surface) of the pole piece 311, eddy current flowing between the 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 according to a basic example of the second embodiment. 2 is a graph showing a Joule loss of 1. The difference between the configuration of the linear motor according to the related technology and the configuration of the linear motor according to the second embodiment is as follows. The former does not have the magnetic pole teeth in a laminated structure. 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 turns of the coil, and the driving conditions were the same. For example, the driving current of the coil was 70.6 A, and the moving speed of the mover was 1000 mm / s.

  The horizontal axis in FIGS. 29A and 29B 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 watts (W). The graph 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 technique in which the magnetic pole teeth are not formed in a laminated structure, the Joule loss in the back yoke is about 80 W, whereas the magnetic pole teeth 31 are formed in a laminated structure. In the linear motor 1, the Joule loss in the back yoke 3 is reduced to about 50W.

  In FIGS. 29A and 29B, the graphs denoted by U, V, and W show the absolute values of the Joule loss due to energization generated in the coils U, V, and W phases, respectively. In FIGS. 29A and 29B, the Joule loss in the coil due to energization of the coil is the same, but there is a great difference in the Joule loss in the back yoke. This result is an example showing that Joule loss due to eddy current can be reduced when the magnetic pole teeth are not laminated under the same dimensions and shape when the laminated structure is used, and the size of the linear motor and the speed of the linear motor are reduced. Although the absolute value of Joule loss due to eddy current changes depending on the eddy current, the ratio of both effects at the same speed is maintained.

  The linear motor 1 according to the second embodiment has the following effects. The magnetic pole teeth 31 are formed by stacking magnetic pole pieces 311 formed of a silicon steel plate. Therefore, the direction of the eddy current is a direction in which the eddy current tends to pass through the plate surface. At this time, the electric resistance of the magnetic pole teeth 31 in the eddy current direction due to the gap between the surfaces of the magnetic pole pieces 311 and the contact resistance between the magnetic pole pieces 311 and the oxide film formed on the surface of the magnetic pole pieces 311 is reduced by the soft magnetic material block. It is larger than the case of forming with. Therefore, the eddy current flowing through the magnetic pole teeth 31 can be reduced. In addition, the surface (laminated surface) of the pole piece 311 may be subjected to insulation treatment such as forming a coating of an insulating material. When the insulation treatment is performed, it becomes possible to further reduce the eddy current between the respective 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 may decrease. In this case, the back yoke 3 may be bent by the suction force generated between the movable element 2 and the movable element 2. 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 does not have a laminated structure. Therefore, the bending of the back yoke 3 is based on a related technique (a case where the magnetic pole teeth 31 and the base plate 32 are each formed of a soft magnetic material, or a case where the magnetic pole teeth 31 and the base plate 32 are integrally formed of a soft magnetic material). It is insignificant even compared to.

(First Modification of Second Embodiment)
The first modification relates to a mode 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 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 stacking a plurality of magnetic pole teeth (plate-like members) 341. The lamination direction of the magnetic pole teeth 341 is a direction that intersects the arrangement direction of the magnetic pole teeth 31. The magnetic pole piece 341 includes a fitted portion 341a, a connection portion 341b, and a plurality of protrusions 341c. The fitted portion 341a has an inverted trapezoidal cross section. The fitted portion 341a is a portion to be the fitted portion 34a of the magnetic pole tooth block 34. The protrusion 341c has a rectangular cross section. The plurality of protrusions 341c are formed at equal pitches in the longitudinal direction of the magnetic pole teeth 341. The protruding portion 341c is a portion serving as 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 teeth 341. The connection portion 341b connects the plurality of protrusions 341c. The magnetic pole piece 341 is formed of, for example, a silicon steel plate. The connection 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 341c is a plate-like member constituting the magnetic pole teeth 31. The magnetic pole tooth piece 341 is formed by integrating two plate-shaped members.

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

  The fitted portion 34a of the magnetic pole tooth block 34 fits into the fitting groove 33a of the base portion 33. In the base portion 33, the length of the mover 2 in the movable direction may be set in accordance with the length of the magnetic pole tooth block 34 in the movable direction. The magnetic pole tooth block 34 is fixed to the base 33 as follows. After the adhesive is applied to one or both of the fitting groove 33a and the fitted 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, 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 the magnetic flux is indicated by a solid arrow, and an example of the eddy current is indicated by a dotted arrow. The reduction of the eddy current in the magnetic pole teeth 31 is the same as in the above-described basic example, and therefore, the description 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, at the connection portion 341b, the magnetic flux flows in the left-right direction on the paper. That is, the magnetic pole teeth 341 constituting the magnetic pole tooth block 34 flow in a direction parallel to the plate surface. The eddy current tends to flow in a direction that prevents a change in the magnetic flux 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 the eddy current is a direction in which the magnetic pole tooth block 341 constituting the magnetic pole tooth block 34 is going to penetrate the plate surface. However, the magnetic pole tooth block 34 is formed by laminating a plurality of magnetic pole teeth 341 and the electric resistance between the magnetic pole teeth 341 is increased, so that eddy current can be reduced. Further, when an insulating coating is applied to the plate surface, the eddy current flowing between the magnetic pole teeth 341 can be further reduced.

  Further, the height of the connection portion 341b will be described. As shown in FIG. 33, the height of the connection part 341b is d. The magnetic flux flowing between the adjacent magnetic pole teeth 31 flows in the left-right direction on the paper. The path through which the magnetic flux flows follows the shortest path. Therefore, no magnetic flux flows in a portion that is at least a certain distance from the magnetic pole teeth 31. Therefore, the height d of the connection portion 341b may be set to a value that allows the magnetic flux in the left-right direction of the paper to flow sufficiently. Further, the base 33 through which the magnetic flux does not flow can be formed of a non-magnetic material. For example, the base 33 is formed of alumina having high rigidity and a large Young's modulus. Alternatively, non-magnetic stainless steel, aluminum alloy, or the like 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 reproduces FIG. 29B again. FIG. 34B is a graph illustrating Joule loss of the linear motor 1 according to the first modification. In the basic example, the magnetic pole teeth 31 have a laminated structure, whereas in the first modification, the magnetic pole teeth and a part of the base plate have a laminated structure. Other conditions, the structure and dimensions of the linear motor, the number of turns of the coil, and the driving conditions were the same. For example, the driving current of the coil was 70.6 A, and the moving speed of the mover was 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 modified example, as shown in FIG. The Joule loss of No. 3 is reduced to about 2.5 W. This is because the eddy current due to the magnetic flux flowing through the connecting portion 341b is also reduced because the connecting portion 341b has a laminated structure. In FIGS. 34A and 34B, the graphs denoted by U, V, and W show the absolute values of the Joule loss due to the energization occurring 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 great difference in the Joule loss in the back yoke. The results show that the latter can reduce Joule loss due to eddy current between the case where only the magnetic pole teeth are laminated under the same dimensions and the case where the magnetic pole teeth and part of the back yoke are laminated. For example, the absolute value of the Joule loss due to the eddy current changes depending on the size of the linear motor and the speed of the linear motor, but the ratio of the two effects at the same speed is maintained.

  In the linear motor 1 according to the first modification, the magnetic pole tooth block 34 is formed by stacking silicon steel plates (magnetic pole teeth 341). The linear motor 1 has, in addition to the magnetic pole teeth 31, a part in the thickness direction from the portion where the back yoke 3 is connected to the magnetic pole teeth 31 has a laminated structure. Therefore, 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 teeth 341. The direction of the eddy current generated by the flow of the magnetic flux is a direction that tends to pass through the plate surface of the magnetic pole tooth 341. However, the electric resistance in the eddy current direction at the connection portion 341b is larger than that in the case where the laminated structure is not formed due to the gap between the surfaces of the magnetic pole teeth 341 and the 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.

  In addition, the first modified example has the following effects in addition to the above-described effects of the first basic example. Since the base 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, for example, alumina. Thereby, the rigidity of the entire back yoke 3 increases, so that it is possible to reduce the bending caused by the suction force generated between the back yoke 3 and the mover 2. Furthermore, when the rigidity of the entire back yoke 3 exceeds the required rigidity due to the material of the base portion 33, the thickness of the back yoke 3 can be reduced.

(Second Modification of Second Embodiment)
The second modification relates to an embodiment 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 302. The back yoke unit 301 includes a base 35 and a magnetic pole tooth unit 36. The back yoke unit 302 includes a base 35 and a magnetic pole tooth unit 37. The difference between the back yoke unit 301 and the back yoke unit 302 is the included magnetic pole tooth unit. One end of the back yoke 3 is referred to as a back yoke unit 301, and the other end is referred to as a back yoke unit 302. Thereby, as shown in FIG. 35, it is possible to configure the back yoke 3 having the magnetic pole teeth 31 at both ends.

  36A and 36B are perspective views showing configuration examples 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 stacking a plurality of magnetic pole teeth (plate-like members) 361. The lamination direction of the magnetic pole teeth 361 is a direction that intersects the direction in which the magnetic pole teeth 31 are arranged. The magnetic pole piece 361 includes a fitted portion 361a, a connection portion 361b, and a plurality of protrusions 361c. The fitted portion 361a has an inverted trapezoidal cross section. The fitted portion 361a is a portion to be the fitted portion 36a of the magnetic pole tooth unit 36. The protrusion 361c has a rectangular cross section. The plurality of protrusions 361c are formed at equal pitches in the longitudinal direction of the magnetic pole teeth 361. The protruding portion 361c is a portion serving as 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 teeth 361. The connection portion 361b connects the plurality of protrusions 361c. The magnetic pole piece 361 is formed 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 361c is a plate-like member constituting the magnetic pole teeth 31. The magnetic pole tooth piece 361 is obtained by integrating two plate-shaped members.

  The magnetic pole tooth unit 37 is formed by stacking a plurality of magnetic pole teeth 371. The lamination direction of the magnetic pole teeth 371 is a direction that intersects the arrangement direction of the magnetic pole teeth 31. The magnetic pole tooth 371 has substantially the same configuration as the magnetic pole tooth 361. The following mainly describes the magnetic pole teeth 371 different from the magnetic pole teeth 361. The magnetic pole piece 371 includes a fitted portion 371a, a connection portion 371b, and a plurality of protrusions 371c. The connecting portion 361b of the magnetic pole tooth piece 361 protrudes in the longitudinal direction at one end in the longitudinal direction. On the other hand, the connecting portions 371b of the magnetic pole teeth 371 do not protrude in the longitudinal direction at both ends in the longitudinal direction. The other configuration of the magnetic pole tooth 371 is the same as that of the magnetic pole tooth 361, and thus the description is omitted.

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

  The fitted portion 36a of the magnetic pole tooth unit 36 or the fitted portion 37a of the magnetic pole tooth unit 37 fits into the fitting groove 35a of the base portion 35. In the base portion 35, the length of the movable element 2 in the movable direction may be set in accordance with the length of the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 in the movable direction. The fixing of the base portion 35 to the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 is performed as follows. The fitting is performed after an adhesive is applied to one or both of the fitting groove 35a and the fitted part 361a or the fitted part 371a. Thereby, the base 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 connecting the plurality of back yoke units 301 and one back yoke unit 302, as shown in FIG. It is formed. The back yoke units 301 and 302 may be connected by a known method, for example, the back surfaces of the back yoke units 301 and 302 may be fixed by rectangular plate members.

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

  In addition, the second modification has the following effects in addition to the above-described effects of the first basic example. Since the base portion 35 which is a part of the back yoke 3 can be formed of a non-magnetic material, it can be formed of a material having a high Young's modulus, for example, alumina. Thereby, the rigidity of the entire back yoke 3 increases, so that it is possible to reduce the bending caused by the suction force generated between the back yoke 3 and the mover 2. Furthermore, when the rigidity of the entire back yoke 3 exceeds the required rigidity due to the material of the base portion 35, the thickness of the back yoke 3 can be reduced. In the second modification, the stroke of the linear motor 1 can be changed by making the number of the back yoke units 301 included in the back yoke 3 variable.

  Although the back yoke units 301 and 302 each have five magnetic pole teeth 31, the number is not limited to five. Although the base 33 has one magnetic pole tooth unit 36 or one magnetic pole tooth unit 37, the present invention is not limited to this. Although the magnetic pole tooth unit 36 and the magnetic pole tooth unit 37 have the same number of magnetic pole teeth 31, respectively, the invention is not limited thereto.

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

  FIG. 38B is a perspective view illustrating a configuration example of the base unit 33. The base 33 shown in FIG. 38B is upside down from the base 33 shown in FIG. 38A. The base portion 33 has a plurality of dovetail grooves (fitting grooves) 33a formed in a rectangular plate material. The dovetail groove 33a has a shape corresponding to the fitted portions 36a and 37a 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 fitted portions 36a and 37a of the magnetic pole tooth units 36 and 37 with an adhesive or the like. The base 33 is formed of a non-magnetic material.

  In the third modified example, in addition to the above-described effects of the first basic example, the following effects are obtained. The base 33, which is a part of the back yoke 3, can be made of a non-magnetic material having a high Young's modulus, for example, alumina. Thereby, the rigidity of the entire back yoke 3 increases, so that it is possible to reduce the bending caused by the suction force generated between the back yoke 3 and the mover 2.

  In the above-described basic example and the first to third modified examples, the gap between the adjacent magnetic pole teeth 31 may be filled with a nonmagnetic material, for example, 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 back yoke 3 and the mover 2 can be more effectively suppressed.

  The base plate 32 in the basic example described above may have a laminated structure in a part (thickness direction) opposite to the direction in which the magnetic pole teeth 31 protrude from the root of the magnetic pole teeth 31. In other words, the magnetic pole teeth 31 (projections 31a, 31a) having a laminated structure may be engaged with the concave portions 32a, 32a in the laminated structure portion of the base plate 32 having a partially laminated structure. This makes it possible to suppress eddy current due to magnetic flux flowing in the movable direction of the mover 2 as in the first and second modifications.

  The technical features (components) described in the embodiments can be combined with each other, and new technical features can be formed by combining the features. The embodiment disclosed this time is an example in all points and should be considered as not being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Linear motor 2 Mover 3 Back yoke 4 Armature 21 Permanent magnet 22 Holding frame 23 Fixing plate 31 Magnetic pole teeth 32 Base plate 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 teeth 43 Drive coil 221 hole 301 Back yoke unit 302 Back yoke unit 311 Magnetic pole piece 341 Magnetic pole tooth 361 Magnetic pole tooth 371 Magnetic pole tooth

Claims (9)

A mover having a magnet array in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator disposed to face the mover with a gap, and a back yoke with a gap in the mover; Is provided with an armature as a stator arranged opposite to the opposite side,
The magnetization direction of each of the plurality of permanent magnets is a thickness direction, and the magnetization directions of adjacent permanent magnets are opposite,
The armature has a plurality of magnetic pole teeth at each of which a drive coil is wound at an equal pitch,
The back yoke has, on a surface facing the mover, a plurality of magnetic pole teeth at the same position in the movable direction of the armature and the mover of the armature,
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 movable element and the back yoke is A linear motor characterized by being equal to or larger than a gap with an 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 twice 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.   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 is variable. The linear motor according to 1. A mover having a magnet array in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator disposed to face the mover with a gap, and a back yoke with a gap in the mover; Is provided with an armature as a stator arranged opposite to the opposite side,
The magnetization direction of each of the plurality of permanent magnets is a thickness direction, and the magnetization directions of adjacent permanent magnets are opposite,
The armature has a plurality of magnetic pole teeth at each of which a drive coil is wound at an equal pitch,
The back yoke has, on a surface facing the mover, a plurality of magnetic pole teeth at the same position in the movable direction of the armature and the mover of the armature,
The magnetic pole teeth of the back yoke are formed by laminating a plurality of plate-shaped members in a direction intersecting a movable direction of the mover. The back yoke has a part in a direction opposite to a direction in which the magnetic pole teeth protrude from a root portion of the magnetic pole teeth, and a plurality of plate members are stacked in the stacking direction of the magnetic pole teeth.
The linear motor according to claim 5, wherein a plate-shaped member forming a laminated portion of the back yoke and a plate-shaped member forming the magnetic pole teeth are integrated. The linear motor according to claim 5, wherein the plurality of plate-shaped members are subjected to insulation treatment on a laminated surface.   The said mover has the holding member which hold | maintains the said magnet arrangement | sequence, The said holding member has several holes in which each of these permanent magnets is inserted. 8. The linear motor according to any one of claims 1 to 7.   The linear motor according to claim 8, wherein the mover has a plate-shaped base material to which the holding member and the plurality of permanent magnets are bonded and fixed.

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