TWI664795B - Linear motor - Google Patents

Abstract

Provided is a linear motor that can achieve a small configuration and generate a large thrust while greatly reducing suction and reducing starting torque. The linear motor system includes: a movable element, which is a magnet array having a plurality of rectangular permanent magnets arranged; a yoke behind the stator, which is arranged opposite to the movable element through a gap; and an armature that is a stator, which The opposite side of the back yoke system is opposite to the mover; the magnetization direction of the plurality of permanent magnets is the thickness direction, and the magnetization directions of adjacent permanent magnets are opposite to each other; the armature system has its own winding drive coils at equal intervals. The back yoke has a plurality of magnetic pole teeth at the same position as the magnetic pole teeth of the armature on the side opposite to the mover.

Description

Linear motor

The invention relates to a linear motor that combines a movable element with a stator and takes out a linear motion output.

Conventionally, a method of converting the output of a rotary motor into linear motion using a ball screw has been used for X and Y movements. However, because of the slow moving speed, a linear motor that can directly take out the linear motion output has been developed. A linear motor is generally composed of a movable element having a plurality of rectangular permanent magnets and an armature having a plurality of magnetic pole teeth.

In addition, since bonding wires and wafers of a processing machine of a semiconductor manufacturing apparatus require high-speed reciprocating motion, it is preferable to use a linear motor with a small mass and a large acceleration. As such a linear motor, for the purpose of miniaturization, for example, as disclosed in Patent Document 1 or 2, a permanent magnet that is not a mover is opposed to the entire surface of the armature that is a stator, and is formed so that A linear motor with a permanent magnet array shorter than the armature.

This linear motor system has a configuration in which a movable element and an armature face each other across a gap. The movable element system has a magnet array in which a plurality of permanent magnets are arranged, and a flat plate-shaped back yoke integrated with the magnet array. The armature system winds the driving coil around a plurality of magnetic pole teeth, respectively. By energizing the drive coil, the mover (magnet arrangement and back yoke) moves, and the difference between the length of the mover and the armature becomes the movable stroke of the linear motor.

In the case where a yoke and a magnet are arranged to form a mover after being formed of a ferromagnetic body, a suction force is generated between the facing stators. Due to the generated suction, a large vertical resistance acts on a bearing that supports the mover to move in a predetermined direction. This vertical resistance causes short-lived bearings. The direction in which the vertical resistance acts is a direction crossing the movable direction of the mover. Therefore, it is necessary to select a bearing in consideration of the vertical resistance. Therefore, the bearing is selected to be larger than a bearing based on the load caused by the mover. This leads to an increase in the size of the entire linear motor.

Therefore, a linear motor (patent documents 3 to 5 and the like) is proposed. This linear motor is a linear motor different from the linear motor described above, in which only the magnets are arranged as a mover, and the back yoke is used as a stator.

In such a linear motor, the magnet array is separated from the flat rear yoke, and the rear yoke and the magnet array are opposed to each other at intervals on the side opposite to the armature system, so that only the magnet array is movable. Only the magnets move in a row, and the back yoke does not move like the armature. The length of the magnet arrangement is shorter than the length of the armature, and the difference between this length becomes the stroke of the linear motor. [Patent Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-269822 [Patent Literature 2] Japanese Republished Patent Publication No. WO2016 / 159034 [Patent Literature 3] Japanese Patent Publication No. 2005-117856 [Patent Literature 4] Japanese Patent Laid-Open No. 2015- 130754 [Patent Document 5] Japanese Patent Laid-Open No. 2005-184984

[Problems to be Solved by the Invention]

The movable element system is strongly attracted by the magnetic pole tooth surface of the armature opposite to it. The suction F at this time is expressed by the following mathematical formula. F = B ² S / 2μ ₀ (where B is the magnetic flux density on the pole teeth of the armature, S is the relative effective area of the movable element and the armature, μ _{0 is} the permeability of the vacuum)

In the case of a linear motor (an integrated linear motor: Patent Document 1 or 2 and the like) having a mover that integrates a magnet array and a flat plate-shaped yoke, the suction force is several times to ten times the normal rated thrust. Therefore, there is a problem that the mover is warped by a large suction force. As a result, the dimensional accuracy of a processing machine using such a warped linear motor is deteriorated. In addition, it is necessary to increase the rigidity of the mover and to increase the size of the structure.

Because an excessively large suction force also affects the linear guides that support the mover, in order to withstand this excessively large suction force, the linear guides need a large rated load. At this point, the size of the structure cannot be avoided. Therefore, it is better to reduce the suction force as shown above. However, in order to reduce the suction force, it is necessary to make it in advance so that both a small structure and a large thrust force can be achieved.

Further, in the integrated linear motor, the cogging effect torque becomes large due to a large edge effect, and there is a problem that the starting torque is large.

Linear motors (separate linear motors: Patent Documents 3 to 5, etc.) configured to separate the magnet array from the flat rear yoke and move only the magnets are arranged because the attraction force from both the rear yoke and the armature acts on the magnet Arranged, so the overall suction force becomes smaller than the integrated linear motor. However, in the case of the separate linear motor, the area of the magnetic poles facing the magnet array is only the area of the pole teeth facing the armature side, and the area of the back yoke side is approximately the same as the total magnet area. Therefore, the magnetic flux density in the two gaps is the same. Because the percentage of the magnetic pole area becomes a large suction force on the back yoke side, the overall suction force cannot be expected to be greatly reduced.

Therefore, it is thought that the gap between the magnet array and the back yoke is widened, and the magnetic flux density of the gap is reduced, so that the attraction force between the magnet array and the back yoke is reduced to the same degree as the attraction force between the magnet array and the armature. However, when the gap between the magnet array and the back yoke is widened, since the magnetic flux density from the armature for generating thrust is also reduced, there is a problem that the thrust is reduced. Therefore, the conventionally proposed separated linear motor has a problem that it is unavoidable to reduce the thrust in order to reduce the suction force acting on the mover.

Also, as described above, in the separation type linear motor, the suction force between the mover (magnet arrangement) and the stator (armature) and the suction force between the mover and the yoke are approximately the same magnitude and are reversed, so It can reduce the suction force acting on the mover. However, it is understood that the eddy current generated in the back yoke during operation is increased because the back yoke is separated from the magnets. An increase in eddy current causes heat. Such a linear motor is not suitable for a device that needs to maintain the ambient temperature within a predetermined range, such as a drive source for a table of a semiconductor manufacturing device.

The present invention was developed in view of the above circumstances, and an object of the present invention is to provide a linear motor that can achieve a small configuration and generate a large thrust while greatly reducing suction and reducing starting torque.

Another object of the present invention is to provide a linear motor that can reduce eddy current while reducing the suction force acting on the magnet array. [Means for solving problems]

The linear motor of the present invention is characterized by comprising: a movable element, which is a magnet arrangement having a plurality of rectangular permanent magnets arranged; a yoke behind the stator, which is arranged opposite to the movable element through a gap; and an armature of the stator, The magnets are arranged opposite to the mover on the side opposite to the back yoke via a gap; the respective magnetization directions of the plurality of permanent magnets are in the thickness direction, and the magnetization directions of adjacent permanent magnets are opposite to each other; the armature system A plurality of magnetic pole teeth each having a driving coil wound at an equal distance; the back yoke is on a surface opposite to the mover, and has a plurality of positions at the same position as the magnetic pole teeth of the armature Magnetic pole teeth; the magnetic pole area of the magnetic pole teeth of the yoke is 0.9 times to 1.1 times the magnetic pole area of the magnetic pole teeth of the armature; the gap between the mover and the yoke; and the distance between the mover and the armature The gap is equal or larger.

The linear motor of the present invention includes: a movable element, a magnet array having a plurality of permanent magnets arranged; a rear yoke, which is arranged opposite to the movable element through a gap; and an armature, which is connected to the rear yoke through a gap. The opposite side is opposite to the mover. The magnets are arranged as a mover, and the back yoke and the armature are used as a stator. A plurality of rectangular permanent magnets arranged in a magnet are each magnetized in the thickness direction, and the direction of magnetization is reversed between adjacent permanent magnets. The armature system has a plurality of magnetic pole teeth at equal intervals, and a driving coil is wound around each magnetic pole tooth. The face of the back yoke and the movable member facing each other is not a flat plate, but a plurality of magnetic pole teeth are formed at equal intervals. The pitch of the pole teeth on the back yoke is equal to the pitch of the pole teeth of the armature. The position of the pole teeth on the back yoke is at the same position as the pole direction of the armature. 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, and the gap between the mover and the back yoke is more than the gap between the mover and the armature.

In the linear motor of the present invention, magnetic pole teeth having substantially the same magnetic pole area are provided at the same position as the rear yoke. In other words, only the rear yoke portion to which the drive magnetic flux from the armature is applied approaches the mover, and a configuration is provided in which the mover is spaced apart from the portion facing the magnetic pole teeth of the armature. Since the magnetic pole area of the armature opposite to the mover and the magnetic pole area of the rear yoke opposite to the mover are approximately equal, they effectively cancel each other out, and the overall suction force is greatly reduced. Therefore, even if the gap between the movable element and the rear yoke is not increased, the suction force can be reduced significantly. At this time, since it is not necessary to increase the gap between the mover and the yoke, the reduction in thrust is small.

In addition, since the concave-convex shape generated by the formation of the magnetic pole teeth of the back yoke generates a cutting area that drives magnetic flux in the back yoke, not only the armature but also the back yoke contributes to the generation of thrust. The generation of this thrust force compensates for the decrease in thrust force caused by increasing the gap (air gap) with the mover to two places, and a large thrust force can be obtained as a whole. Therefore, while maintaining a large thrust force, the suction force acting on the magnet array (movable element) can be greatly reduced.

In the linear motor of the present invention, the mover is disposed between an armature having a plurality of magnetic pole teeth at an equal interval, and a back yoke having a plurality of magnetic pole teeth in a movable direction at the same position as the magnetic pole teeth of the armature. Structure, the cogging effect torque of the magnet array in the direction perpendicular to the moving direction is reduced, and it is possible to reduce the starting torque of the mover.

When the magnetic pole area of the magnetic pole teeth of the yoke becomes too wide, a lot of magnetic flux is picked up from the surroundings, and the suction force becomes large. On the other hand, when the magnetic pole area of the magnetic pole teeth of the yoke becomes too narrow, it is used to: The magnetic flux that gets the thrust decreases, and the thrust decreases. Therefore, 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.

Because the magnetic pole teeth of the armature are wound with the drive coil, the magnetic pole teeth of the armature are not too low, and the height of the magnetic pole teeth of the armature becomes higher than the height of the magnetic pole teeth of the back yoke. Therefore, since the height of the back yoke magnetic pole teeth is low, magnetic flux is also generated in portions other than the magnetic pole teeth, and the suction force tends to become larger than the armature side. Therefore, in order to cancel the suction with high efficiency, the gap between the movable element and the rear yoke and the gap between the movable element and the armature are made equal or relatively large.

The linear motor system of the present invention is characterized in that the height of the magnetic pole teeth of the back yoke is 1/20 times or more and 2 times or less the distance between the magnetic pole teeth.

In the linear motor of the present invention, when the height of the magnetic pole teeth of the back yoke is much smaller than the distance, the effect of providing the magnetic pole teeth (concave-convex shape) cannot be obtained. On the other hand, the height of the magnetic pole teeth of the back yoke is much larger than the distance. In this case, the effect remains the same, but it is not conducive to miniaturization. Therefore, the height of the magnetic pole teeth of the yoke is made 1/20 times or more and 2 times or less the distance between the magnetic pole teeth.

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

In the linear motor of the present invention, the length of the mover is shorter than the length of each of the armature and the back yoke. Therefore, it has a small structure and can ensure a large acceleration. In addition, since the edge effect becomes smaller, the cogging effect torque becomes smaller, and it is possible to reduce the starting torque.

The linear motor system of the present invention is characterized in that the size of the gap between the movable element and the back yoke and / or the size of the gap between the movable element and the armature are variable.

In the linear motor of the present invention, the size of the gap between the mover and the back yoke and / or the size of the gap between the mover and the armature are variable. Therefore, according to the magnitude of the driving magnetomotive force during use, the gap between the movable element and the back yoke and / or the gap between the movable element and the armature can be adjusted, thereby making the suction force almost zero.

The linear motor of the present invention is characterized by comprising: a movable element, which is a magnet arrangement having a plurality of rectangular permanent magnets arranged; a yoke behind the stator, which is arranged opposite to the movable element through a gap; and an armature of the stator, The magnets are arranged opposite to the mover on the side opposite to the back yoke via a gap; the respective magnetization directions of the plurality of permanent magnets are in the thickness direction, and the magnetization directions of adjacent permanent magnets are opposite to each other; the armature system A plurality of magnetic pole teeth each having a driving coil wound at an equal distance; the back yoke is on a surface opposite to the mover, and has a plurality of positions at the same position as the magnetic pole teeth of the armature Magnetic pole teeth; the magnetic pole teeth of the back yoke are formed by laminating a plurality of plate-shaped members in a direction crossing the movable direction of the mover.

In the linear motor of the present invention, the magnetic pole teeth have a laminated structure, which can reduce the suction force acting on the mover and reduce the eddy current.

The linear motor system of the present invention is characterized in that a part of the back yoke system from the root of the magnetic pole teeth and the protruding direction system of the magnetic pole teeth is formed by laminating a plurality of plate-like members in a direction in which the magnetic pole teeth are laminated; The plate-shaped member of the laminated portion of the back yoke is integrated with the plate-shaped member constituting the magnetic pole teeth.

In the linear motor of the present invention, a yoke current can be further reduced by forming a laminated structure of a part in the thickness direction from the connection portion with the magnetic pole teeth by the back yoke. In addition, since the plate-like member constituting the laminated portion of the back yoke and the plate-like member constituting the magnetic pole teeth are integrated, manufacturing man-hours are reduced.

The linear motor system of the present invention is characterized in that the plurality of plate-like members are subjected to insulation treatment on the build-up layer.

In the linear motor of the present invention, the eddy current can be further reduced because a plurality of plate-like members are subjected to insulation treatment on the build-up layer.

The linear motor system of the present invention is characterized in that the movable element has a holding member for holding the magnet arrangement, and the holding member has a plurality of holes into which the plurality of permanent magnets can be inserted.

In the linear motor of the present invention, a magnet array (a plurality of permanent magnets) is held by a holding member. Therefore, since the rigidity of the movable element (magnet arrangement) becomes large, warping, bending, and the like of the permanent magnet are less likely to occur, and the starting torque can be reduced.

The linear motor system of the present invention is characterized in that: the movable element is provided with the holding member and a plate-shaped base material for fixing and fixing the plurality of permanent magnets.

In the linear motor of the present invention, in a state where a plurality of permanent magnets are inserted into the holes of the holding member, the magnet array (the plurality of permanent magnets) and the holding member are adhered and fixed to the plate-shaped base material. Thereby, the rigidity of the movable element (magnet arrangement) is further improved, and the starting torque is further reduced, and the permanent magnet can be prevented from falling off. [Inventive effect]

In the linear motor of the present invention, while achieving a small structure and generating a large thrust force, suction force acting on the mover (magnet arrangement) can be greatly reduced, and the starting torque of the mover can be reduced. Therefore, it is possible to suppress the deformation caused by the warpage accompanying the large suction force, and to prevent the dimensional accuracy of the device using the linear motor from being deteriorated. Because the suction force can be made smaller, the rigidity of the mover and the rigidity of the support system that supports the mover can be reduced. Not only can it be miniaturized, but also the acceleration can be improved by reducing the mass of the moveable mass. In addition, since the magnetic pole tooth structure is provided on the back yoke, since a thrust force from the back yoke is added to the movable element, the gap between the magnet array and the back yoke can reduce the reduction of the thrust force to a minimum.

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

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments of the present invention. (First Embodiment)

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 the configuration of the mover 2 of the linear motor 1 in the first embodiment. In addition, in FIGS. 1 and 2, only the movable element 2 is a cross section taken from a direction parallel to the movable direction in order to know the arrangement of the magnet.

The linear motor 1 includes a mover 2, a yoke 3, and an armature 4. The rear yoke 3 is disposed so as to face each other with a gap therebetween, and the armature 4 is disposed so as to be opposite to the movable member 2 on the side opposite to the rear yoke 3 system. The rear yoke 3 and the armature 4 function as a stator.

As shown in FIG. 4, the movable element 2 having a long shape includes a plurality of permanent magnets 21, a holding frame 22, and a fixing plate 23. The side-by-side direction of the plurality of permanent magnets 21 becomes the longitudinal direction of the movable element 2. Each of the permanent magnets 21 is formed in a rectangular shape. Each of the permanent magnets 21 is, for example, an Nd-Fe-B based rare earth magnet. Each of the permanent magnets 21 is magnetized in the thickness direction (upper and lower directions in FIG. 2), and the direction of magnetization between adjacent permanent magnets 21 and 21 is reversed. That is, the permanent magnets 21 magnetized in a direction from the armature 4 side to the armature 4 side and the permanent magnets 21 magnetized in a direction from the armature 4 side to the armature 4 side are arranged alternately in the magnet array.

As shown in FIG. 4, the holding frame 22 is formed in a rectangular plate shape. The thickness of the holding frame 22 is thinner than that of the permanent magnet 21. A plurality of rectangular holes 221 are provided in the holding frame 22. The holding frame 22 is made of a non-magnetic material such as SUS or aluminum. The hole 221 is formed in a shape corresponding to the permanent magnet 21. Each permanent magnet 21 is inserted into the hole 221 and fixed to the holding frame 22 with an adhesive. The holes 221 are provided to the permanent magnets 21 fixed to the holding frame 22 in parallel at equal intervals. When the permanent magnet 21 is fixed to the holding frame 22, the pair of holes 221 is fitted so that the magnetization direction between the adjacent permanent magnets 21 and 21 becomes reverse. As shown in FIG. 3, the permanent magnets 21 are arranged obliquely at an attention angle θ.

In a state where the plurality of permanent magnets 21 are inserted into the holes 221 of the holding frame 22 and held, the holding frame 22 is fixed to the fixing plate 23 with an adhesive. The bottom surface of the permanent magnet 21 is also adhered to the fixing plate 23. The fixing plate 23 is made of non-magnetic SUS. In this way, because the magnets are arrayed and held on the holding frame 22 and adhered to the fixed plate 23, the rigidity of the movable member 2 is high, and the permanent magnet 21 does not fall off. The movable element 2 is arranged between the rear yoke 3 and the armature 4 so that the fixed plate 23 and the rear yoke 3 face each other. The fixing plate 23 is not necessary, and is not necessary when the permanent magnet 21 is sufficiently held by the holding frame 22.

The lengths of the rear yoke 3 and the armature 4 in the movable direction (the left-right direction in FIG. 2) are approximately equal, and the length of the movable member 2 in the movable direction (the left-right direction in FIG. 2) is longer than those of the rear yoke 3 and The length of the armature 4 is shorter, and the difference between this length becomes the movable stroke of the linear motor 1. By this configuration, the edge effect is reduced.

The surface of the back yoke 3 on the side opposite to the mover 2 made of soft steel (such as a silicon steel plate) is preferably a flat plate shape, but the surface of the back yoke 3 on the side opposite to the mover 2 is flat. Instead of a flat plate shape, a plurality of rectangular magnetic pole teeth 31 are formed at regular intervals in the movable direction. The height of each magnetic pole tooth 31 is preferably 1/20 times or more and 2 times or less, and 1/10 times or more and 1 time or less the formation pitch of the magnetic pole teeth 31. For example, the height of each magnetic pole tooth 31 is about half of the formation pitch of the magnetic pole teeth 31.

In the armature 4, a plurality of rectangular magnetic pole teeth 42 of a soft magnetic system are integrally provided at an equal interval in the movable direction to the core 41 of the soft magnetic system, and a drive coil 43 is wound around each of the magnetic pole teeth 42.

The distance between the magnetic pole teeth 31 of the rear yoke 3 and the magnetic pole teeth 42 of the armature 4 are equal. The position of the magnetic pole teeth 31 of the rear yoke 3 is in the movable direction of the mover 2 and the magnetic pole teeth 42 of the armature 4. In the same position. In addition, the shape of the magnetic pole surface of the magnetic pole teeth 31 of the back yoke 3 opposite to the movable body 2 is formed into a rectangular shape substantially the same as that of the magnetic pole teeth 42 of the armature 4 and the magnetic pole surface facing the movable body 2. The magnetic pole area is 0.9 to 1.1 times that of the latter. For example, the magnetic pole surfaces of the magnetic pole teeth 31 and the magnetic pole surfaces of the magnetic pole teeth 42 are the same rectangle and have the same area. The gap between the movable element 2 and the rear yoke 3 and the gap between the movable element 2 and the armature 4 are equal or relatively large. For example, the clearance of the latter is 0.5 mm, and the clearance of the former is 0.5 mm or more. Even if the gap between the movable element 2 and the rear yoke 3 in this case includes a fixed plate 23 in structure, the thickness of the fixed plate 23 is not included, and the distance (shortest distance) between the movable element 2 itself and the rear yoke 3 is shown. In other words, this gap is a magnetic gap (magnetic gap), regardless of the thickness of the non-magnetic fixing plate 23.

The linear motor 1 of the first embodiment has as its basic structure a seven-pole six-slot having seven permanent magnets 21 and six magnetic pole teeth 31 and magnetic pole teeth 42 facing each other. The form shown in FIGS. 1 and 2 has a 14-pole 12-slot configuration that doubles the basic configuration.

In the linear motor 1 of the first embodiment, a magnetic pole tooth 31 is formed on the side of the back yoke 3 opposite to the movable element 2. The magnetic pole tooth 31 is the same as the magnetic pole tooth 42 of the armature 4 in the moving direction. The positions have magnetic pole faces of approximately the same shape, and the magnetic pole areas are approximately equal. Therefore, the magnitude of the suction force generated between the movable element 2 and the back yoke 3 and the magnitude of the suction force generated between the movable element 2 and the armature 4 become substantially equal, because the upper and lower directions of the two sides in FIG. 2 The suction force effectively cancels, so the suction system of the linear motor 1 acting on the mover 2 as a whole becomes small. In this way, in the linear motor 1 of the first embodiment, the suction force can be greatly reduced without increasing the gap between the movable element 2 and the rear yoke 3. Therefore, since it is not necessary to increase the gap between the movable element 2 and the rear yoke 3, a reduction in thrust does not occur.

In the linear motor 1 of the first embodiment, as described above, the armature 4 having a plurality of magnetic pole teeth 42 at equal intervals is the same as the armature 4 having the magnetic pole teeth 42 of the armature 4 in the movable direction. The position has a configuration in which the movable element 2 is arranged between the rear yoke 3 of the plurality of magnetic pole teeth 31. Therefore, the cogging effect torque of the magnet array in a direction perpendicular to the movable direction is reduced, and it is possible to reduce the starting of the movable element 2. Torque. Furthermore, since the magnets are held by the holding frame 22 and fixed to the fixing plate 23, the rigidity of the movable member 2 can be increased, and deformation such as warping and bending of the permanent magnet 21 is difficult to occur. Helps reduce the starting torque of the mover 2.

In the linear motor 1 of the first embodiment, a plurality of magnetic pole teeth 31 are formed on the rear yoke 3, and a cutting area for driving magnetic flux is generated by the concave-convex shape opposite to the movable member 2. Therefore, not only the armature 4 but also the rear The 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 Figure 5, arrows indicate the flow of magnetic flux. In the linear motor 1, a thrust is generated by cutting the magnetic flux on the armature 4 side, and a thrust is also generated by cutting the magnetic flux on the yoke 3 side. The thrust generated by the linear motor 1 becomes the two thrusts. with. In addition, since the magnetic pole teeth 31 shown in the first embodiment are not formed and the rear yoke is a flat linear motor, no thrust is generated on the rear yoke side, and it is generated only by cutting the magnetic flux on the armature 4 side. Thrust.

The linear motor 1 in the first embodiment. Since a gap is also provided between the movable element 2 and the rear yoke 3, there is a fear that the thrust may be reduced due to the gap. However, as described above, since the thrust force can also be generated on the back yoke 3 side, a reduction in the thrust force caused by the gap is compensated, and a large thrust force can be realized.

From the above, the linear motor 1 of the first embodiment is used. While maintaining a large thrust, the suction force acting on the mover 2 can be greatly reduced. Therefore, the movable body 2 is hardly warped by suction, and the dimensional accuracy is high in a processing machine or the like of a semiconductor manufacturing apparatus using the linear motor 1.

In addition, in the linear motor 1 of the first embodiment, it is not necessary to use a permanent magnet 21 and a holding frame 22 having a small rigidity. Therefore, the movable element 2 can be miniaturized, and a large acceleration can be realized with the lightening of the movable element 2. In addition, since the wear of the movable member 2 is also small, the life of the linear motor 1 can be extended.

In order to move the mover smoothly in the linear motor, as will be described later, a linear guide is generally provided on the side of the mover. However, in the linear motor 1 of the first embodiment, the suction force is reduced, so the linear guide can also be used. The smaller rigidity also contributes to the miniaturization and longevity of the linear motor.

In the linear motor 1 of the first embodiment, the length of the movable element 2 is made shorter than that of the back yoke 3 and the armature 4 in order to achieve further reduction in size, weight, and speed.

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

First, mover 2 is produced. From the Nd-Fe-B series rare-earth magnet (B _r = 1.395T, H _cJ = 1273kA / m), 14 rectangular permanent magnets 21 having a thickness of 5 mm, a width of 12 mm, and a length of 82 mm were cut. The cut permanent magnet 21 is excited in the thickness direction. Next, from a SUS board with a thickness of 3 mm, a holding frame 22 as shown in FIG. 4 was cut by wire cutting. The cut holding frame 22 is adhered and fixed to a fixing plate 23 composed of a SUS plate having a thickness of 0.2 mm. Then, the 14 permanent magnets 21 to which the adhesive is applied are provided with an inclination angle θ = 3.2 ° such that the magnetization directions of the adjacent permanent magnets 21 are reversed from each other, and are inserted into the holes 221 of the holding frame 22, thereby fixing the permanent magnets. 21 is adhered and fixed to the holding frame 22 and the fixing plate 23. Here, in order to achieve both the weight reduction of the movable element 2 and the large rigidity of the magnet arrangement, the thickness of the holding frame 22 is made 3 mm with respect to the thickness of the permanent magnet 21 5 mm.

In addition, it is different from the above example, and it is also possible to produce a holding frame 22 by stacking 6 pieces of a SUS plate with a thickness of 0.5 mm by punching and drilling and fixing it by a gap filling process. In this case, it is attempted to reduce production costs.

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

From soft steel (JIS G3101 type mark SS400 material), a block having a size as shown in Fig. 6 is cut, and 18 equally-shaped magnetic pole teeth 31 (width: 6mm, height :) are produced at equal intervals (15.12mm). 3mm, length: 82mm, magnetic pole area 492mm ² ).

Then, an armature 4 is produced. Fig. 7 is a plan view showing an armature material used for producing an armature 4 of the linear motor 1 of the first embodiment. Cut out 164 pieces of silicon steel plate (JIS standard C2552 type designation 50A800 material) with a thickness of 0.5 mm to form an armature material 44 as shown in Fig. 7. The cut 164 pieces are overlapped and a CO ₂ laser is used. The sides are melted into one body to obtain a block with a width of 82mm, a height of 31mm, and a length of 263.04mm (equally spaced (15.12mm) in the iron core 41. There are 18 magnetic pole teeth 42 (width: 6mm, height: 25mm, length: 82mm, magnetic pole area 492mm ² )).

Next, insert the windings into this block. Fig. 8 is a diagram showing the windings of the armature 4 of the linear motor 1 according to the first embodiment. The enamel-coated wire with a diameter of 2 mm was wound 17 times and dipped in varnish and fixed to the arms of each magnetic pole tooth 42 of the armature 4, thereby forming a driving coil 43.

U, V, and W in FIG. 8 represent U-phase, V-phase, and W-phase of a 3-phase AC power supply, respectively, and the coil systems of each phase are connected in series. U-coil, V-coil, and W-coil are wired so that current flows in a clockwise direction when viewed from above, and -U coil, -V coil, and -W coil are wired in a counter-clockwise direction when viewed from above. Make an armature 4. Then, each of the six U coils, V coils, W coils, -U coils, -V coils, and -W coils is star-wired, and then connected to a 3-phase AC power source.

Then, using a jig, the yoke 3 and the armature 4 after the production were fixed so that the interval between them was fixed at 6 mm. In addition, the gap between the rear yoke 3 and the armature 4 is fixed to 6 mm, but this gap is adopted as a structure that can be adjusted after the linear motor 1 is assembled. Next, after mounting a linear guide (not shown) on the side of the movable element 2, the movable element 2 having a thickness of 5 mm is inserted into the rear yoke 3 and the armature at a predetermined distance from the rear yoke 3 and the armature 4, respectively. 4 gaps, while the linear motor 1 was produced. At this time, the distance between the gap between the movable element 2 and the magnetic pole teeth 31 of the back yoke 3 and the gap between the movable element 2 and the magnetic pole teeth 42 of the armature 4 were both 0.5 mm. In order to measure the suction force, a force gauge is provided between the linear guide and the armature 4.

Since the gap between the rear yoke 3 and the armature 4 can be adjusted, the distance between the movable body 2 and the armature 4 (magnetic pole teeth 42) is fixed, and the movable body 2 and the rear yoke can be arbitrarily set. The distance of the gap of 3 (magnetic pole teeth 31) can be adjusted. In addition, by adjusting the insertion position of the movable element 2 to the gap between the rear yoke 3 and the armature 4, the distance between the gap of the movable element 2 and the rear yoke 3 (magnetic pole teeth 31), and the movable element 2 and the armature can be adjusted. The ratio of the distances of the gaps of 4 (magnetic pole teeth 42) is set 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 rear yoke 3, a mechanism for adjusting the height by inserting a gap adjustment screw or inserting a cross-sectional shape by the screw can be adopted. A mechanism for adjusting the height by forming a tapered gap filler plate.

9A and 9B are diagrams showing the configuration of the linear motor 1 as an example of the first embodiment produced in this way, and FIG. 9A is a top view thereof and FIG. 9B is a side view thereof. In FIG. 9B, a blank arrow indicates the direction of magnetization of the permanent magnet 21, and a solid arrow indicates the direction of movement of the movable element 2. The details of the manufacturing specifications of the linear motor 1 are as follows.

Magnetic pole structure: 7-pole 6-slot permanent magnet 21 Material: Nd-Fe-B series rare earth magnet (Hitachi Metal NMX-S49CH material) Shape of permanent magnet 21: 5.0mm thickness, 12mm width, 82mm length permanent magnet 21 Interval: 12.96mm Tilt angle of permanent magnet 21: 3.2∘ Shape of back yoke 3: thickness 6.0mm, width 90mm, length 263.04mm Material of back yoke 3: mild steel (JIS standard G3101 type mark SS400 material) Shape: Width: 6.0mm, Height: 3.0mm, Length: 82mm Pitch of the magnetic pole teeth 31: 15.12mm Physique of the core 41: Height 31mm, width 82mm, length 263.04mm Material of the core 41: Silicon steel plate (JIS standard C2552 Type Symbol 50A800 material) Shape of magnetic pole teeth 42: width: 6.0mm, height: 25mm, length: 82mm Pitch of magnetic pole teeth 42: 15.12mm Shape of drive coil 43: width: 15.12mm, height: 23mm, length: 91.12mm drive coil Winding thickness of 43: 4.06mm Diameter and number of windings of drive coil 43: 2mm in diameter, 17 turns of winding resistance (one): 0.0189Ω Mass of movable element 2: 516.6g

In the linear motor 1 described above, the length (190 mm) of the mover 2 is shorter than the lengths of both the 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 equal to 15.12 mm. The magnetic pole teeth 31 and the magnetic pole teeth 42 are located at the same position in the moving direction.

The shape of the magnetic pole surface of the magnetic pole teeth 31 opposed to the magnet arrangement and the shape of the magnetic pole surface of the magnetic pole teeth 42 opposed to the magnet arrangement are rectangular in the same size. That is, the width of the magnetic pole teeth 31 (the size in the movable direction) and the width of the magnetic pole teeth 42 (the size in the movable direction) are equal to 6 mm, and the magnetic pole area of the magnetic pole teeth 31 facing the magnet arrangement is opposite to that of the magnetic arrangement. The magnetic pole areas of the facing magnetic pole teeth 42 are equal, and both are 492 mm ² .

The linear motor 1 assembled in this manner was set on a test bench for thrust measurement, and was driven by a three-phase AC power source synchronized with the position of the mover 2 (magnet arrangement) to move the mover 2 to measure thrust and suction.

Fig. 10 is a graph showing a thrust force change of the linear motor 1 with respect to an electric angle as an example of the first embodiment. This thrust change indicates the thrust (position of U-phase, V-phase, W-phase, 3) of the position of the movable element 2 when the driving magnetomotive force (= the magnitude of the driving current × the number of turns of the driving coil 43) is taken as 1200A. (Combined thrust). In Fig. 10, the horizontal axis is the electrical angle [∘], and the vertical axis is the thrust [N]. In Fig. 10, a indicates the thrust of the borrowed armature 4; b in Fig. 10 indicates the thrust of the borrowed yoke 3; and c in Fig. 10 indicates the overall thrust (the thrust of the borrowed armature 4 and the borrowed The total thrust of the thrust of the yoke 3). As shown in FIG. 10, it was found that a substantially large thrust can be obtained over the entire area.

Fig. 11 is a graph showing the thrust characteristics of the linear motor 1 as an example of the first embodiment. This thrust characteristic is a characteristic indicating a case where the current applied to the drive coil 43 is changed. In Fig. 11, the horizontal axis driving magnetomotive force [A], the left vertical axis system thrust [N], and the right vertical axis system thrust magnetomotive force ratio [N / A]. In FIG. 11, a indicates the thrust, and b indicates the thrust magnetomotive force ratio in FIG. 11. In this linear motor 1, the thrust ratio 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 suction characteristics of the linear motor 1 as an example of the first embodiment. This suction characteristic is a characteristic indicating a case where the current applied to the drive coil 43 is changed. In Fig. 12, the horizontal axis is driving magnetomotive force [A], and the vertical axis is suction [N]. The suction system indicates that the movable element 2 is attracted to the + armature 4 side, and the movable element 2 is attracted to the-side yoke 3 side. As the driving magnetomotive force increases, the suction force gradually increases. For example, when the driving magnetomotive force is 1200A, the movable element 2 is attracted to the rear yoke 3 side with a suction force of about 290N.

In addition, in order to evaluate the linear motor 1 of the first embodiment in comparison with the conventional linear motor, two types of linear motors (first and second conventional examples) were prepared as conventional examples, and those linearities were measured. Motor characteristics (thrust and suction).

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

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

The configuration of the magnet array 52 is the same as the configuration of the magnet array of the movable element 2 described above. That is, the magnet array 52 is configured such that a plurality of rectangular permanent magnets 55 are fixedly fixed to a non-magnetic holding frame at equal intervals, and are arranged in a movable direction (left-right direction in FIG. 13). Each of the permanent magnets 55 It is magnetized in the thickness direction (upward and downward direction in FIG. 13), and the direction of magnetization between adjacent permanent magnets 55 and 55 is reversed. In the linear motor 50 of the first conventional example, the magnet array 52 is adhered to a flat plate-shaped yoke 53 made of mild steel. The structure of the armature 54 is the same as that of the armature 4 described above. A plurality of magnetic pole teeth 57 are integrally provided on the core 56 at equal intervals in the movable direction, and a drive coil 58 is wound around each of the magnetic pole teeth 57. .

14A and 14B are diagrams showing the configuration of the linear motor 50 of the first conventional example, and FIG. 14A is a top view thereof and FIG. 14B is a side view thereof. In FIG. 14B, a blank arrow indicates the direction of magnetization of the permanent magnet 55, and a solid arrow indicates the direction of movement of the movable element 51. The gap between the movable element 51 and the armature 54 is 0.5 mm or 1 mm. Details of the manufacturing specifications of the linear motor 50 are shown below.

Magnetic pole structure: 7-pole 6-slot permanent magnet 55 Material: Nd-Fe-B series rare-earth magnet (Hitachi Metals NMX-S49CH material) Shape of permanent magnet 55: 5.0mm thick, 12mm wide, 82mm long permanent magnet 55 Interval: 12.96mm Tilt angle of permanent magnet 55: 3.2∘ Shape of yoke 53: thickness 6.0mm, width 90mm, length 190mm Material of yoke 53: mild steel (JIS standard G3101 type mark SS400 material) Physique of core 56: Height 31mm, width 82mm, length 263.04mm Material of core 56: silicon steel plate (JIS standard C2552 type designation 50A800 material) Shape of magnetic pole teeth 57: width: 6.0mm, height: 25mm, length: 82mm Pitch of magnetic pole teeth 57: 15.12 mm Shape of the driving coil 58: width: 15.12mm, height: 23mm, length: 91.12mm Winding thickness of the driving coil 58: 4.06mm Diameter and number of windings of the driving coil 58: 2mm in diameter, 17 turns of winding resistance (1 Pcs): mass of 0.0189Ω mover 51 (magnet arrangement 52 + back yoke 53): 1321.01g

The length of the movable element 51 (integrated structure of the magnet array 52 and the back yoke 53) in the movable direction (left-right direction of FIG. 13) is shorter than that in the armature 54, and the difference between this length becomes the linear motor 50 The actionable stroke.

Next, a second conventional example will be described. Fig. 15 is a side view showing the structure of a linear motor according to a second conventional example. The second conventional example is a linear motor (a separate type linear motor) having a configuration according to Patent Documents 3 to 6. In addition, in FIG. 15, only the magnet arrangement 62 shows a cross section from a direction parallel to the movable direction in order to understand the arrangement of the magnets.

The linear motor 60 of the second conventional example includes a magnet array 62, a rear yoke 63 disposed opposite to the magnet array 62 with a gap therebetween, and a magnet yoke 62 disposed opposite to the magnet array 62 on the side opposite to the rear yoke 63 system with a gap therebetween. Armature 64. Only the magnet array 62 functions as a mover, and the rear 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 movable element 2 described above. In other words, the magnet array 62 is configured by fixing a plurality of rectangular permanent magnets 65 to a non-magnetic holding frame at equal intervals and placing the permanent magnets 65 in a movable direction (left-right direction in FIG. 15). It is magnetized in the thickness direction (upward and downward direction in FIG. 15), and the direction of magnetization between adjacent permanent magnets 65 and 65 is reversed. The mild steel yoke 63 is not only the surface on the side not facing the magnet array 62, but also the surface on the side opposite to the magnet array 62. The magnetic pole tooth system of the linear motor 1 of the first embodiment does not exist. . The structure of the armature 64 is the same as that of the armature 4 described above. A plurality of magnetic pole teeth 67 are integrally provided on the iron core 66 at equal intervals in the movable direction, and a drive coil 68 is wound around each of the magnetic pole teeth 67. .

16A and 16B are diagrams showing the structure of the linear motor 60 of the second conventional example, and FIG. 16A is a top view thereof and FIG. 16B is a side view thereof. In FIG. 16B, a blank arrow indicates the direction of magnetization of the permanent magnet 65, and a solid arrow indicates the direction of movement of the magnet array 62 (movable element). The gap between the magnet array 62 and the back yoke 63 and the gap between the magnet array 62 and the armature 64 are both 0.5 mm. The details of the manufacturing specifications of the linear motor 60 are as follows.

Magnetic pole structure: 7-pole 6-slot permanent magnet 65 Material: Nd-Fe-B series rare earth magnet (Hitachi Metals NMX-S49CH material) Shape of permanent magnet 65: 5.0mm thickness, 12mm width, 82mm length permanent magnet 65 Interval: 12.96mm Tilt angle of permanent magnet 65: 3.2∘ Shape of back yoke 63: thickness 6.0mm, width 90mm, length 215mm Material of back yoke 63: mild steel (JIS standard G3101 type mark SS400 material) Core 66 body: Height 31mm, width 82mm, length 263.04mm Material of core 66: silicon steel plate (JIS standard C2552 type designation 50A800 material) Shape of magnetic pole teeth 67: Width: 6.0mm, height: 25mm, length: 82mm Pitch of 67 pole teeth 67: 15.12 mm Drive coil 68 shape: width: 15.12mm, height: 23mm, length: 91.12mm winding thickness of the drive coil 68: 4.06mm diameter, number of turns of the winding of the drive coil 68: 2mm diameter, 17 turns winding resistance (1 Pcs): Mass of 0.0189Ω mover (magnet arrangement 62): 516.6g

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 becomes the movable stroke of the linear motor 60.

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

Fig. 17 is a graph showing the average thrust of a linear motor in the first, second, and first examples. FIG. 17 shows the average thrust [N] when the driving magnetomotive force is set to 1200A. Fig. 18 is a graph showing the average suction force of the linear motor in the first, second, and first examples. FIG. 18 shows the average suction force [N] when the driving magnetomotive force is set to 1200A. Here, the average thrust and the average suction are measured (calculated) at 25 points of thrust and suction at intervals of 15 ° from the U-phase electrical angle of 0 ° to 360 °, and the average values are calculated.

In FIGS. 17 and 18, A is a first conventional example in which the magnet array 52 and the back yoke 53 are integrated, and the gap between the movable element 51 and the armature 54 is a linear motor 50 (hereinafter also referred to as a linear Motor 50A), B is a linear motor 50 (hereinafter also referred to as linear motor 50B) of the first conventional example in which the magnet array 52 and the back yoke 53 are integrated, and the gap between the movable element 51 and the armature 54 is 1 mm. In the second conventional example in which the magnet array 62 is separated from the back yoke 53, the gap between the magnet array 62 and the armature 64 and the gap between the magnet array 62 and the armature 64 are made into a linear motor 60 of 0.5 mm. The magnetic pole teeth 31 are formed as an example of the first embodiment of the rear yoke 3 separated from the movable element 2 (magnet arrangement). The gap between the movable element 2 and the rear yoke 3 and the gap between the movable element 2 and the armature 4 are both 0.5. mm linear motor 1.

In the linear motor 50A (A in the figure) of the first conventional example, although the maximum thrust is 1030N, the suction force is 4200N, which is about four times the thrust. With regard to the linear motor 50B (B in the figure) as a countermeasure for reducing the suction force, the thrust force obtained is significantly reduced to 909N, and the suction force is 3360N, which is not too low. Therefore, understanding is not a sufficient countermeasure.

In the linear motor 60 (C in the figure) of the second conventional example, a relatively large thrust force of 980N can be obtained, but the suction force is 1712N, which is attracted by the yoke 63 side, and the suction force is not sufficiently reduced.

On the other hand, in the linear motor 1 (D in the figure), which is an example of the first embodiment, a thrust force of 1000 N which is not inferior to that of the linear motor 50A can be obtained. In addition, the suction force can be greatly reduced to 290N on the 3 side of the back yoke (about 1/14 of the linear motor 50A). Therefore, in the linear motor 1 as an example of the first embodiment, it was confirmed that the suction force can be greatly reduced while maintaining a large thrust force.

In the linear motor 1 as an example of the first embodiment, as shown in FIG. 12, the magnitude of the suction force is changed according to the magnitude of the driving magnetomotive force. Therefore, if the thrust area (driving magnetomotive force) is used in conjunction with the usual use, and the gap between the movable element 2 and the rear yoke 3 is adjusted, the suction force can be made smaller.

In the example of the first embodiment described above, the gap between the movable element 2 and the rear yoke 3 and the gap between the movable element 2 and the armature 4 are equal to 0.5 mm. However, in the other examples of the first embodiment, the movable element is The gap between 2 and armature 4 is still 0.5mm, and the gap between movable element 2 and rear yoke 3 is made 0.74mm. The other structures are the same as those of the above-mentioned example.

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

In other examples, when the driving magnetomotive force is 1200A, the thrust system becomes 978N, which is slightly worse than the above example, but as for the suction force, when the driving magnetomotive force is 1200A, it is only 18N, which can achieve almost zero. This is the suction force that can ignore the level of deformation or life reduction caused by suction force on the linear guide, the mover, or the surrounding structures. Therefore, it is known that the driving magnetomotive force is used at about 1200A. The linear motor 1 of another example is more suitable for the purpose of reducing the suction force than the above one.

As another example of the first embodiment, a linear motor 1 having a gap of 0.5 mm between the movable element 2 and the armature 4 and a 0.66 mm gap between the movable element 2 and the rear yoke 3 was produced. The other structures are the same as those of the above-mentioned example.

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

Furthermore, in other examples, when the driving magnetomotive force is 1200A, the thrust system becomes 984N, which is slightly worse than the above example, but as for the suction force, when the driving magnetomotive force is 600A, there is only 5N, which can achieve almost zero. It is known that the driving magnetomotive force is used at about 600A, and the linear motor 1 of the other example is most suitable for reducing the suction force.

From the above, the optimal size of the gap between the movable element 2 and the rear yoke 3 can be set in accordance with the use area with high frequency, the suction force can be greatly reduced, and almost zero can be achieved. As a result, it is possible to prevent deterioration in dimensional accuracy caused by warping of the movable element 2 (magnet arrangement), reduction in life of the linear guide due to excessive load, and the like.

Moreover, in the above-mentioned form, the example which fixed the magnitude | size of the gap of the movable element 2 and the armature 4 and changed the magnitude of the gap of the movable element 2 and the back yoke 3 was demonstrated. However, it is also possible to use the fixed movable element 2 to the contrary Examples where the size of the gap with the rear yoke 3 changes the size of the gap between the movable element 2 and the armature 4, the example where the size of the gap between the rear yoke 3 and the armature 4 is fixed and the position of the movable element 2 changes, etc. Achieve near zero suction.

Also, in the above-mentioned form, the linear motor 1 having a shorter movable body 2 than the armature 4 has been described. However, the linear motor having a longer movable body than the armature 4 has the characteristics of the present invention ( The magnetic pole teeth are formed on the back yoke).

(Basic example of the second embodiment)

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. In addition, in FIGS. 23 and 24, in order to understand the arrangement of the magnets only for the movable element 2 series, cross sections taken from a direction parallel to the movable direction are shown.

Like the first embodiment, the linear motor 1 of the second embodiment includes a movable element 2, a rear yoke 3, and an armature 4, and the rear yoke 3 and the armature 4 function as a stator.

In addition, since the configuration of the mover 2 and the armature 4 of the linear motor 1 in the second embodiment is the same as the configuration of the mover 2 and the armature 4 of the linear motor 1 in the first embodiment, the description is omitted. .

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

The rear yoke 3 and the armature 4 are opposed to each other with a gap therebetween. The movable element 2 is arranged in the gap. The first surface of the movable element 2 is opposed to the rear yoke 3 through a gap. A second surface facing the first surface of the movable member 2 is opposed to the armature 4 through a gap.

As shown in FIG. 24, the lengths of the rear yoke 3 and the armature 4 in the movable direction (the left-right direction in FIG. 24) are substantially equal. The pitch of the magnetic pole teeth 31 in the back yoke 3 is equal to the interval between the magnetic pole teeth 42 of the armature 4. The positions of the magnetic pole teeth 31 on the back yoke 3 are the same in the movable direction of the movable element 2 as the positions of the magnetic pole teeth 42 of the armature 4. The magnetic pole surfaces of the magnetic pole teeth 31 and the magnetic pole surfaces of the magnetic pole teeth 42 are the same rectangle and have the same area. The gap between the movable element 2 and the rear yoke 3 and the gap between the movable element 2 and the armature 4 are substantially equal.

In the movable element 2, the magnetization directions of the adjacent permanent magnets 21 and 21 are reversed. When the movable element 2 is disposed between the yoke 3 and the armature 4, the permanent magnets 21 that are magnetized in a direction from the yoke 3 side to the armature 4 side and the armature 4 side to the yoke are alternately disposed. The structure of the permanent magnet 21 magnetized in three directions.

During the operation of the linear motor 1, a suction force is generated between the magnetic pole teeth 31 of the rear yoke 3 and the permanent magnet 21 of the mover 2. In addition, a suction force is also generated between the magnetic pole teeth 42 of the armature 4 and the permanent magnet 21 of the mover 2. The two types of suction forces acting on the mover 2 are opposite to each other. By adjusting the magnetic pole surfaces of the magnetic pole teeth 31 and the magnetic pole surfaces of the magnetic pole teeth 42 to make the same rectangle or the same area, the magnitude of the suction force can be made substantially equal. This makes it possible to balance the suction force generated between the magnetic pole teeth 31 and the permanent magnet 21 and the suction force generated between the magnetic pole teeth 42 and the permanent magnet 21. That is, it is possible to cancel the two types of suction. In addition, when it is difficult to balance the two types of suction due to processing errors, assembly errors, and the like, 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 types of suction.

As described above, since the linear motor 1 of the second embodiment has the same configuration as the linear motor 1 of the first embodiment described above, the linear motor 1 of the second embodiment is also linear with the first embodiment. Like the motor 1, while maintaining a large thrust, the suction force acting on the mover 2 can be greatly reduced. Also, the linear motor 1 of the second embodiment can reduce the starting torque of the mover 2 in the same manner as the linear motor 1 of the first embodiment.

Hereinafter, the structure of the yoke 3 which is a characteristic 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 yoke 3. The magnetic pole teeth 31 are formed in a T-shaped cross section, and have two protruding portions 31a, 31a protruding from the bottom (on the lower side in FIG. 25) in the short-side direction. (For this reason, in the figure 25, the H-shape is laid horizontally.) The protruding portions 31a and 31a are portions that engage with the concave portions 32a and 32a of the dovetail groove 321 described later. When the linear motor 1 operates, the short-side direction of the magnetic pole teeth 31 is a direction parallel to the movable direction of the movable element 2.

The magnetic pole teeth 31 are formed by laminating magnetic pole pieces 311. The magnetic pole piece 311 includes a protruding portion 311 a for engagement formed by cutting out a rectangular plate-shaped portion. The magnetic pole piece 311 is formed of a thin plate such as silicon steel having soft magnetic properties. Fixing the laminated magnetic pole pieces 311 to each other is performed by thermal welding, gap filling, or the like. In the case of thermal welding, for example, first, a surface of the magnetic pole piece 311 is coated with a thermosetting adhesive or a film having a thermal welding added thereto, and then the plate surface is heated while applying pressure. Between the magnetic pole pieces 311 is fixed by heating.

In addition, the thinner the thickness of the magnetic pole pieces 311 constituting the magnetic pole teeth 31, that is, the more the number of the magnetic pole pieces 311 is increased, the less the eddy current loss is. If the strength or labor and time for assembly are considered, the thickness of the magnetic pole piece 311 is preferably about 0.2 to 0.5 mm. The number or thickness of the magnetic pole pieces 311 constituting the magnetic pole teeth 31 may be appropriately designed in accordance with the required specifications.

FIG. 26 is a partial perspective view showing a configuration example of the bottom plate 32 included in the back yoke 3. Fig. 26 is drawn for convenience of explanation, and the up-down direction is opposite to Figs. 24 and 25. The bottom plate 32 is provided with a dovetail groove 321 along the short side direction. The dovetail groove 321 is formed in a shape corresponding to the protruding portion 311 a of the magnetic pole piece 311 (the protruding portion 31 a of the magnetic pole tooth 31). The dovetail groove 321 has a recessed portion 32a corresponding to the protruding portion 311a (the protruding portion 31a). As shown in FIGS. 24 and 25, a plurality of dovetail grooves 321 are formed in the bottom plate 32. The plurality of dovetail grooves 321 are arranged at equal intervals along the movable direction of the movable element 2. The arrangement direction of the plurality of dovetail grooves 321 is a direction parallel to the movable direction of the mover 2 when the linear motor 1 is operated.

FIG. 27 is a partial perspective view showing the yoke 3. As in Fig. 26, for convenience of explanation, the up-down direction is drawn opposite to Figs. 24 and 25. In the rear yoke 3, the protruding portion 31 a of the magnetic pole tooth 31 is engaged with the dovetail groove 321.

The fixing system of the magnetic pole teeth 31 to the base plate 32 is performed as follows, for example. An adhesive is applied to one or both of the dovetail groove 321 and the magnetic pole teeth 31. The positioning of inserting the magnetic pole teeth 31 into the dovetail groove 321 is performed using a jig or the like. After the adhesive has hardened, remove the jig. The fixing method is not limited to this. As long as the distance between the magnetic pole teeth 31 or the protrusion amount of the magnetic pole teeth 31 from the base plate 32 is within a predetermined error range, other methods may be used.

The linear motor 1 generates a magnetic flux flowing through the magnetic pole teeth 42 of the armature 4, the permanent magnets 21 of the mover 2, and the magnetic pole teeth 31 of the yoke 3 by applying three-phase AC to the drive coil 43 of the armature 4. The magnetic force generated between the movable element 2 and the armature 4 and the suction force generated between the movable element 2 and the yoke 3 become the thrust of the movable element 2 and the movable element 2 moves.

Next, the reduction of eddy current will be explained. FIG. 28 is a partial side view showing the linear motor 1. In FIG. 28, an example of the flow direction of magnetic flux is shown by an arrow of a solid line, and an example of eddy current is shown by an arrow of a dotted line. As shown in FIG. 28, magnetic flux flows in the magnetic pole teeth 31 in the vertical direction on the paper surface. That is, it flows in a direction parallel to the plate surface of the magnetic pole piece 311 constituting the magnetic pole teeth 31. The eddy current is intended to flow in a direction that obstructs the change of the magnetic flux on a plane perpendicular to the flow direction of the magnetic flux. That is, in the case shown in FIG. 28, it is intended to flow in a direction orthogonal to the flow direction of the magnetic flux and counterclockwise. The direction of this eddy current is a direction to penetrate the plate surface of the magnetic pole piece 311 constituting the magnetic pole teeth 31. However, the magnetic pole teeth 31 are formed by laminating a plurality of magnetic pole pieces 311. Since the resistance between the magnetic pole pieces 311 is large, eddy currents can be reduced. Furthermore, when an insulating film is applied to the plate surface (surface) of the magnetic pole piece 311, the eddy current flowing between the magnetic pole pieces 311 can be further reduced.

Figures 29A and 29B are graphs showing examples of Joule losses caused by eddy currents, and Figure 29A is a graph showing Joule losses of linear motors according to related technologies. A graph of the Joule loss of the linear motor 1 as a basic example. The difference between the configuration of the linear motor according to the related art and the linear motor 1 in the second embodiment is as follows. The former is a laminated structure without magnetic pole teeth. For example, the former magnetic pole tooth is a piece of soft magnetic body. Alternatively, the base plate 32 and the magnetic pole teeth 31 may be integrally formed of a soft magnetic body. In contrast, the latter magnetic pole teeth 31 have a laminated structure. Other conditions, the structure, size and number of turns of the linear motor, and the driving conditions are the same. For example, the drive current of the coil is 70.6A, and the moving speed of the mover is taken as 1000mm / s.

The horizontal axes in FIGS. 29A and 29B show the electrical angle of the position of the movable element 2. The units on the horizontal axis are degrees (°). The Joule losses caused by the eddy currents on the vertical axis of Figs. 29A and 29B. The unit is tile (W). The yoke attached graph shows the Joule loss at the yoke. As shown in FIG. 29A, in the linear motor according to the related technology in which the magnetic pole teeth are not formed with a laminated structure, the Joule loss at the back yoke is about 80 W, and the linear motor of the second embodiment is formed with a laminated structure on the magnetic pole teeth 31. 1. The Joule loss at the back yoke 3 is reduced to about 50W.

In Figs. 29A and 29B, the graphs appended with U, V, and W represent the eddy current loss caused by the energization generated in the coils U, V, and W phases, respectively, in absolute values. In addition, in FIGS. 29A and 29B, the Joule loss in the coil caused by the energization of the coil is the same, but the Joule loss in the back yoke is greatly different. This result is an example of the case where the relative magnetic pole teeth are not formed as a laminated structure under the same size and shape. When the magnetic pole teeth are formed as a laminated structure, the Joule loss caused by eddy current can be reduced. The absolute value of the Joule loss caused by the eddy current changes, but the percentage of the effect of both at the same speed is maintained.

The linear motor 1 of the second embodiment has the following effects. The magnetic pole teeth 31 are formed by laminating magnetic pole pieces 311 formed of a silicon steel plate. Therefore, the direction of the eddy current is a direction to penetrate the plate surface. At this time, due to the gap on the surface of the magnetic pole piece 311 or the contact resistance between the magnetic pole pieces, the oxide film formed on the surface of the magnetic pole piece 311, the resistance system in the direction of the eddy current of the magnetic pole teeth 31 becomes softer than that of a soft magnetic body. It is often the case that the blocks form the magnetic pole teeth 31. Therefore, the eddy current flowing to the magnetic pole teeth 31 can be reduced. In addition, an insulation treatment such as a coating that forms an insulating substance may be applied to the surface (layer surface) of the magnetic pole piece 311. When an insulation treatment is applied, the eddy current can be further reduced between the silicon steel plates.

Furthermore, in the second embodiment, the magnetic pole teeth 31 included in the back yoke 3 have a laminated structure. For example, when a laminated steel plate is formed on the entire back yoke, there is a concern that the rigidity is reduced. In this case, the suction force generated between the movable element 2 and the rear yoke 3 may be warped. However, in the basic example, only the magnetic pole teeth 31 have a laminated structure, and the base plate 32 on which the magnetic pole teeth 31 are fixed does not have a laminated structure. Therefore, the warpage of the back yoke 3 is based on a related technology (a case where the magnetic pole teeth 31 and the base plate 32 are formed by a soft magnetic body or a case where the magnetic pole teeth 31 and the base plate 32 are formed integrally by a soft magnetic body). More slight. (First modification of the second embodiment)

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

FIG. 31 is a perspective view showing a configuration example of the magnetic pole tooth block 34. The magnetic pole tooth block 34 is formed by laminating a plurality of magnetic pole tooth pieces (plate-like members) 341. The stacked direction of the magnetic pole tooth pieces 341 is a direction crossing the arrangement direction of the magnetic pole teeth 31. The magnetic pole tooth pieces 341 include a fitted portion 341a, a connection portion 341b, and a plurality of protruding portions 341c. The fitted portion 341a has an inverted trapezoidal cross section. The fitted portion 341 a is a portion that becomes the fitted portion 34 a of the magnetic pole tooth block 34. The protruding portion 341c has a rectangular cross section. The plurality of protruding portions 341 c are formed at equal intervals in the longitudinal direction of the magnetic pole tooth piece 341. The protruding portion 341 c is a portion that becomes the magnetic pole teeth 31 of the magnetic pole tooth block 34. The connection portion 341 b is a portion between the fitted portion 341 a and the protruding portion 341 c in the height direction of the magnetic pole tooth piece 341. The connecting portion 341b connects a plurality of protruding portions 341c. The magnetic pole teeth 341 are formed of, for example, a silicon steel plate. The connecting portion 341 b is a plate-like member constituting a laminated portion that becomes a part of the bottom portion of the back yoke 3. The protruding portion 341 c is a plate-like member constituting the magnetic pole teeth 31. The magnetic pole tooth 341 is formed by integrating two plate-like members.

Fig. 32 is a perspective view showing a configuration example of the bottom portion 33. The bottom 33 shown in FIG. 32 reverses the upper and lower sides with the bottom 33 shown in FIG. 30. The bottom portion 33 is formed in a rectangular plate shape. The bottom portion 33 forms a fitting groove 33a having a trapezoidal cross section.

The fitted portion 34 a of the magnetic pole tooth block 34 is fitted into the fitting groove 33 a of the bottom portion 33. In addition, at the bottom portion 33, the length in the movable direction of the movable element 2 may be set in accordance with the length in the movable direction of the magnetic pole tooth block 34. The fixing system of the magnetic pole tooth block 34 to the bottom portion 33 is performed 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 bottom part 33 and the magnetic pole tooth block 34 are fixed. As a result, the back yoke 3 is formed.

Next, the reduction of eddy current will be explained. FIG. 33 is a partial side view of the linear motor 1. In FIG. 33, an example of the flow direction of the magnetic flux is indicated by an arrow of a solid line, and an example of an eddy current is indicated by an arrow of a dotted line. The reduction of the eddy current in the magnetic pole teeth 31 is the same as the above-mentioned basic example, and therefore description thereof is omitted. Here, reduction of the eddy current at the connection portion 341 b of the magnetic pole tooth block 34 will be described. As shown in FIG. 33, the magnetic flux flows in the left-right direction of the paper surface at the connection portion 341b. That is, it flows in a direction parallel to the plate surface of the magnetic pole tooth piece 341 constituting the magnetic pole tooth block 34. The eddy current is intended to flow in a direction that obstructs the change of the magnetic flux on a plane perpendicular to the flow direction of the magnetic flux. That is, as shown in FIG. 33, it is intended to flow in the counterclockwise direction using the flow direction of the magnetic flux as an axis. The direction of this eddy current is a direction through which the plate surface of the magnetic pole tooth piece 341 constituting the magnetic pole tooth block 34 is intended. However, the magnetic pole tooth block 34 is formed by laminating a plurality of magnetic pole tooth pieces 341. Since the resistance system between the magnetic pole tooth pieces 341 becomes large, the eddy current can be reduced. Furthermore, when an insulating film is applied to the plate surface, the eddy current flowing between the magnetic pole tooth pieces 341 can be further reduced.

The height of the connection portion 341b will be described. As shown in FIG. 33, the height of the connection portion 341b is taken as d. The magnetic flux flowing between the adjacent magnetic pole teeth 31 flows in the left-right direction of the paper surface. The path through which the magnetic flux flows is the shortest path. Therefore, the magnetic flux does not flow in a portion of the distance from the magnetic pole teeth 31 by a predetermined value or more. Therefore, the height d of the connection portion 341b may be set so that the magnetic flux in the left-right direction of the paper surface can sufficiently flow. In addition, the bottom portion 33 where the magnetic flux does not flow can be formed of a non-magnetic material. For example, the bottom portion 33 is formed of aluminum or the like having high rigidity and a large Young's modulus. Alternatively, non-magnetic stainless steel or aluminum alloy can be used.

34A and 34B are graphs showing an example of the Joule loss caused by the eddy current, and FIG. 34A is a graph showing the Joule loss of the linear motor 1 in the basic example. Figure 34A re-discloses Figure 29B. FIG. 34B is a graph showing the Joule loss of the linear motor 1 according to the first modification. In the relative basic example, the magnetic pole teeth 31 have a laminated structure. In the first modified example, a part of the magnetic pole teeth and the bottom plate have a laminated structure. Other conditions, the structure, size and number of turns of the linear motor, and the driving conditions are the same. For example, the drive current of the coil is 70.6A, and the moving speed of the mover is taken as 1000mm / s.

As shown in FIG. 34A, in the linear motor 1 of the basic example, the Joule loss with respect to the rear yoke 3 is about 50 W, and in the linear motor 1 of the first modification, as shown in FIG. 34B, the rear yoke 3 The Joule loss is reduced to about 2.5W. Since the connection portion 341b has a laminated structure, the eddy current caused by the magnetic flux flowing to the connection portion 341b is also reduced. In FIGS. 34A and 34B, the graphs appended with U, V, and W represent eddy current losses caused by energization generated in the coil U-phase, V-phase, and W-phase, respectively, in absolute values. In addition, in FIGS. 34A and 34B, the Joule loss in the coil caused by the energization of the coil is the same, but the Joule loss in the back yoke is greatly different. This result shows the case where only the magnetic pole teeth have a laminated structure and the magnetic pole teeth and the back yoke have a laminated structure under the same size and shape. The latter can reduce the Joule loss caused by eddy current. According to the linear example, The absolute value of the Joule loss caused by the eddy current varies with the size of the motor or the speed of the linear motor, but the percentage of the effect of both 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 laminating silicon steel plates (magnetic pole tooth pieces 341). The linear motor 1 has a laminated structure including not only the magnetic pole teeth 31 but also a part in the thickness direction from the connection portion between the rear yoke 3 and the magnetic pole teeth 31. Therefore, the magnetic flux system flowing to the connection portion 341 b between the adjacent magnetic pole teeth 31 is parallel to the surface of the magnetic pole tooth piece 341. The direction of the eddy current generated by the flow of the magnetic flux is a direction to penetrate the plate surface of the magnetic pole tooth plate 341. However, the resistance in the direction of the eddy current of the connection portion 341b becomes larger than that in the case where the laminated structure is not formed due to the gap on the surface of the magnetic pole tooth piece 341 or the oxide film formed on the surface. Therefore, the eddy current flowing to the connection portion 341b can be reduced. Therefore, the eddy current flowing to the back yoke 3 can be further reduced.

Moreover, in the first modification, not only the above-mentioned effects of the first basic example, but also the following effects. Since the bottom portion 33 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 large Young's modulus, such as alumina. Therefore, since the rigidity of the rear yoke 3 as a whole is increased, the warpage caused by the suction force generated between the rear yoke 3 and the movable body 2 can be reduced. Furthermore, depending on the material of the bottom portion 33, when the rigidity exceeds the rigidity required for the entire rear yoke 3, the rear yoke 3 can be made thin. (Second Modification of Second Embodiment)

The second modification relates to a form in which a part of the bottom plate 32 constituting the back yoke 3 has a laminated structure. FIG. 35 is a side view showing another configuration example of the yoke 3. The back yoke 3 system includes a plurality of back yoke units 301 and a back yoke unit 302. The rear yoke unit 301 includes a bottom 35 and a magnetic pole tooth unit 36. The back yoke unit 302 includes a bottom 35 and a magnetic pole tooth unit 37. The difference between the back yoke unit 301 and the back yoke unit 302 is a difference between the included magnetic pole tooth units. One end of the back yoke 3 is referred to as the back yoke unit 301, and the other end is referred to as the back yoke unit 302. Thereby, as shown in FIG. 35, the back yoke 3 provided with the magnetic pole teeth 31 in both ends can be comprised.

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

The magnetic pole tooth unit 36 is formed by laminating a plurality of magnetic pole tooth pieces (plate-shaped members) 361. The stacked direction of the magnetic pole tooth pieces 361 is a direction crossing the arrangement direction of the magnetic pole teeth 31. The magnetic pole tooth pieces 361 include a fitted portion 361a, a connection portion 361b, and a plurality of protruding portions 361c. The fitted portion 361a has an inverted trapezoidal cross section. The fitted portion 361 a is a portion that becomes the fitted portion 36 a of the magnetic pole tooth unit 36. The protruding portion 361c has a rectangular cross section. The plurality of protruding portions 361c are formed at equal intervals in the length direction of the magnetic pole tooth piece 361. The protruding portion 361 c is a portion that becomes the magnetic pole teeth 31 of the magnetic pole tooth unit 36. The connection portion 361b is a portion between the fitted portion 361a and the protruding portion 361c in the height direction of the magnetic pole tooth piece 361. The connecting portion 341b connects a plurality of protruding portions 361c. The magnetic pole teeth 361 are formed of, for example, a silicon steel plate. The connection portion 361 b is a plate-like member constituting a laminated portion that becomes a part of the bottom portion of the back yoke 3. The protruding portion 361 c is a plate-like member constituting the magnetic pole teeth 31. The magnetic pole tooth 361 is formed by integrating two plate-like members.

The magnetic pole tooth unit 37 is formed by laminating a plurality of magnetic pole tooth plates 371. The stacked direction of the magnetic pole tooth pieces 371 is a direction crossing the arrangement direction of the magnetic pole teeth 31, and the magnetic pole tooth pieces 371 have substantially the same structure as the magnetic pole tooth pieces 361. In the following, the differences between the magnetic pole teeth 371 and the magnetic pole teeth 361 will be mainly described. The magnetic pole piece 371 includes a fitted portion 371a, a connection portion 371b, and a plurality of protruding portions 371c. The connecting portion 361b of the magnetic pole tooth piece 361 is an end in one of the longitudinal directions and protrudes in the longitudinal direction. In contrast, the connection portions 371b of the magnetic pole tooth pieces 371 are at both ends in the longitudinal direction, and do not protrude in the longitudinal direction. The other configuration of the magnetic pole tooth 371 is the same as that of the magnetic pole tooth 361, so the description is omitted.

FIG. 37 is a perspective view showing a configuration example of the bottom portion 35. The bottom 35 shown in FIG. 37 reverses the upper and lower sides and the bottom 35 shown in FIG. 35. The bottom portion 35 is formed in a rectangular plate shape. The bottom portion 35 forms a fitting groove 35 a having a trapezoidal cross section.

The fitted portion 36 a of the magnetic pole tooth unit 36 or the fitted portion 37 a of the magnetic pole tooth unit 37 is fitted into the fitting groove 35 a of the bottom portion 35. In addition, at the bottom portion 35, the length in the movable direction of the movable element 2 may be set in accordance with the length in the movable direction of the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37. The bottom 35 is fixed to the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 as follows. After the adhesive is applied to one or both of the fitting groove 35a and the fitted portion 361a or the fitted portion 371a, the fitting is performed. Thereby, the bottom part 35 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. Further, in accordance with the stroke of the linear motor 1, the number of the yoke units 301 is selected, and a plurality of the yoke units 301 and one yoke unit 302 are combined, thereby forming the yoke 3 as shown in FIG. 35. . Each of the rear yoke units 301 and the rear yoke unit 302 is combined according to a well-known method. For example, the rear surfaces of the rear yoke units 301 and 302 may be fixed by rectangular plate-shaped 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 tooth pieces 361 and 371). The linear motor 1 has a laminated structure including not only the magnetic pole teeth 31 but also a part in the thickness direction from the connection portion between the rear yoke 3 and the magnetic pole teeth 31. Therefore, the magnetic flux system flowing between the adjacent magnetic pole teeth 31 to the connection portions 361b and 371b is parallel to the surfaces of the magnetic pole tooth pieces 361 and 371. The direction of the eddy current generated by the flow of the magnetic flux is a direction to penetrate the plate surfaces of the magnetic pole tooth pieces 361 and 371. However, due to the gap between the surfaces of the magnetic pole tooth pieces 361 and 371 or the oxide film formed on the surfaces, the resistance in the direction of the eddy current of the connection portions 361b and 371b becomes larger than that in the case where no multilayer structure is formed. Therefore, the eddy current flowing to the connection portions 361b and 371b can be reduced. Therefore, the eddy current flowing to the back yoke 3 can be further reduced.

Moreover, in the second modification, not only the above-mentioned effects of the first basic example, but also the following effects. Since the bottom 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 large Young's modulus, such as alumina. Therefore, since the rigidity of the rear yoke 3 as a whole is increased, the warpage caused by the suction force generated between the rear yoke 3 and the movable body 2 can be reduced. Furthermore, depending on the material of the bottom portion 35, when the rigidity exceeds the rigidity required for the entire rear yoke 3, the rear yoke 3 can be made thin. Further, in the second modification, the number of the rear yoke units 301 included in the rear yoke 3 can be changed to change the stroke of the linear motor 1.

The number of magnetic pole teeth 31 provided in each of the back yoke units 301 and 302 is five, but it is not limited to this. The bottom 35 is assumed to be provided with the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37, but it is not limited to this. The magnetic pole tooth unit 36 and the magnetic pole tooth unit 37 each have the same number of magnetic pole teeth 31, but it is not limited to this.

(Third Modification of Second Embodiment)

The third modification is the second modification and relates to a configuration in which the bottom portion 35 is formed as a single plate. Fig. 38A is a side view showing another configuration example of the yoke 3. The back yoke 3 includes a bottom portion 33, a plurality of magnetic pole tooth units 36, and a magnetic pole tooth unit 37. Since the configurations of the magnetic pole tooth unit 36 and the magnetic pole tooth unit 37 are the same as those of the second modification described above, description thereof will be omitted.

FIG. 38B is a perspective view showing a configuration example of the bottom portion 33. FIG. The bottom 33 shown in FIG. 38B reverses the upper and lower sides and the bottom 33 shown in FIG. 38A. The bottom portion 33 has a plurality of dovetail grooves (fitting grooves) 33a formed in a rectangular plate shape. The shape of the dovetail groove 33 a is a shape corresponding to the fitted portions 36 a and 37 a of the magnetic pole tooth units 36 and 37. The back yoke 3 is fixed to the dovetail groove 33a of the bottom 33 with an adhesive or the like after the dovetail groove 33a of the bottom 33 is fitted to the fitted portions 36a and 37a of the magnetic pole tooth units 36 and 37.

In the third modification, not only the above-mentioned effects of the first basic example but also the following effects are obtained. This is because the bottom portion 33 which is a part of the back yoke 3 can be made of a non-magnetic material having a large Young's modulus, such as alumina. Therefore, since the rigidity of the rear yoke 3 as a whole is increased, the warpage caused by the suction force generated between the rear yoke 3 and the movable member 2 can be reduced.

In the above-mentioned basic example and the first to third modified examples, a gap between the adjacent magnetic pole teeth 31 may be embedded by a non-magnetic material such as a resin mold. Thereby, the strength of the rear yoke 3 is increased, and the warpage of the rear yoke 3 caused by the suction generated between the movable yoke 2 and the movable body 2 can be more effectively suppressed.

The base plate 32 of the above-mentioned basic example may be formed as a laminated structure from a part of the root of the magnetic pole teeth 31 and a part of the protruding direction of the magnetic pole teeth 31 in the opposite direction (thickness direction). In other words, the magnetic pole teeth 31 (protruding portions 31a, 31a) of the laminated structure may be engaged with the recessed portions 32a, 32a in a laminated structure portion of the bottom plate 32 having a laminated structure. Thereby, as in the first modification and the second modification, it is possible to suppress eddy current caused by magnetic flux flowing in the movable direction of the movable element 2.

The technical features (constitutive elements) described in each embodiment can be combined with each other, and a new technical feature can be formed by combining them. The embodiment disclosed this time is an example on all matters and should not be considered as a limitation. The scope of the present invention is not the meaning described above, but according to the scope of the patent application, it is intended to include all changes within the meaning and scope equivalent to the scope of the patent application.

1‧‧‧ Linear Motor

2‧‧‧ mover

3‧‧‧ yoke

4‧‧‧ armature

21‧‧‧Permanent magnet

22‧‧‧ holding frame

23‧‧‧Fixing plate

31‧‧‧ magnetic pole teeth

32‧‧‧ floor

33‧‧‧ bottom

34‧‧‧ Magnetic pole tooth block

35‧‧‧ bottom

36‧‧‧ Magnetic tooth unit

37‧‧‧ Magnetic pole tooth unit

41‧‧‧Iron 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

Fig. 1 is a perspective view showing a configuration of a linear motor according to a first embodiment. Fig. 2 is a side view showing the configuration of the linear motor of the first embodiment. Fig. 3 is a plan view showing the configuration of a mover of the linear motor in the first embodiment. Fig. 4 is an exploded perspective view showing a configuration of a mover of the linear motor in the first embodiment. Fig. 5 is a side view showing the flow of magnetic flux in the linear motor of the first embodiment. Fig. 6 is a view showing a side shape of a yoke of the linear motor of the first embodiment. Fig. 7 is a plan view showing an armature material used in the production of the armature of the linear motor of the first embodiment. Fig. 8 is a view showing an armature winding of the linear motor in the first embodiment. Fig. 9A is a top view showing the configuration of the linear motor of the first embodiment. Fig. 9B is a side view showing the configuration of the linear motor of the first embodiment. Fig. 10 is a graph showing a thrust force change of an electric angle of a linear motor as an example of the first embodiment. Fig. 11 is a graph showing thrust characteristics of a linear motor as an example of the first embodiment. Fig. 12 is a graph showing the suction characteristics of a linear motor as an example of the first embodiment. Fig. 13 is a side view showing the configuration of a linear motor of the first conventional example (a configuration in which a magnet array is integrated with a back yoke as a mover). Fig. 14A is a top view showing the structure of the linear motor of the first conventional example. Fig. 14B is a side view showing the configuration of the linear motor of the first conventional example. Fig. 15 is a side view showing the structure of a linear motor of a second conventional example (a structure in which magnets are arranged as a mover and a flat plate-shaped yoke is used as a stator). Fig. 16A is a top view showing the structure of a linear motor according to a second conventional example. Fig. 16B is a side view showing the structure of a linear motor according to a second conventional example. Fig. 17 is a graph showing the average thrust of a linear motor in the first, second, and first examples. FIG. 18 is a graph showing the average suction force of a linear motor in the first, second, and first examples. Fig. 19 is a graph showing thrust characteristics of a linear motor according to another example of the first embodiment. Fig. 20 is a graph showing suction characteristics of a linear motor according to another example of the first embodiment. Fig. 21 is a graph showing thrust characteristics of a linear motor according to another example of the first embodiment. Fig. 22 is a graph showing suction characteristics of a linear motor according to another example of the first embodiment. Fig. 23 is a perspective view showing a configuration example of a linear motor according to a second embodiment. Fig. 24 is a side view showing a configuration example of a linear motor according to a second embodiment. Fig. 25 is a perspective view showing a configuration example of magnetic pole teeth included in the yoke. Fig. 26 is a partial perspective view showing a configuration example of a bottom plate included in the back yoke. Fig. 27 is a partial perspective view showing the yoke. Fig. 28 is a partial side view showing the linear motor. FIG. 29A is a graph showing the Joule loss of a linear motor according to the related technology. Fig. 29B is a graph showing the Joule loss of the linear motor in the basic example of the second embodiment. Fig. 30 is a side view showing another configuration example of the yoke. Fig. 31 is a perspective view showing a configuration example of a magnetic pole tooth block. Fig. 32 is a perspective view showing a configuration example of the bottom portion. Figure 33 is a partial side view of the linear motor. Fig. 34A is a graph showing the Joule loss of the linear motor in the basic example of the second embodiment. Fig. 34B is a graph showing the Joule loss of the linear motor in the first modification of the second embodiment. Fig. 35 is a side view showing another configuration example of the yoke. Fig. 36A is a perspective view showing a configuration example of a magnetic pole tooth unit. Fig. 36B is a perspective view showing a configuration example of a magnetic pole tooth unit. Fig. 37 is a perspective view showing a configuration example of the bottom portion. Fig. 38A is a side view showing another configuration example of the yoke. Fig. 38B is a perspective view showing a configuration example of the bottom portion.

Claims (9)

A linear motor is characterized by comprising: a movable element, a magnet array having a plurality of rectangular permanent magnets arranged; a yoke behind the stator, arranged opposite to the movable element through a gap; and an armature of the stator, the system The movable body is disposed opposite to the rear yoke through a gap, and 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 to each other. A plurality of magnetic pole teeth each having a driving coil wound at an equal distance; the back yoke is on a surface opposite to the movable element, and has a plurality of magnetic poles at the same position as the magnetic pole teeth of the armature Teeth; 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; Equal or larger. For example, the linear motor of item 1 of the patent application range, wherein the height of the magnetic pole teeth on the back yoke is 1/20 times or more and 2 times or less the distance between the magnetic pole teeth. For example, the linear motor of claim 1 or 2, wherein the length of the movable element is shorter than the length of the armature and shorter than the length of the yoke. For example, in the linear motor of the first patent application, 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. A linear motor is characterized by comprising: a movable element, a magnet array having a plurality of rectangular permanent magnets arranged; a yoke behind the stator, arranged opposite to the movable element through a gap; and an armature of the stator, the system The movable body is disposed opposite to the rear yoke through a gap, and 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 to each other. A plurality of magnetic pole teeth each having a driving coil wound at an equal distance; the back yoke is on a surface opposite to the movable element, and has a plurality of magnetic poles at the same position as the magnetic pole teeth of the armature Teeth; the magnetic pole teeth of the back yoke are formed by laminating a plurality of plate-like members in a direction crossing the movable direction of the mover. For example, the linear motor of item 5 of the patent application, wherein a part of the back yoke system from the root of the magnetic pole teeth and the protruding direction system of the magnetic pole teeth is formed by laminating a plurality of plate-like members in a direction in which the magnetic pole teeth are laminated The plate-like member constituting the laminated portion of the back yoke and the plate-like member constituting the magnetic pole teeth are integrated. For example, the linear motor of claim 5 or 6, wherein the plurality of plate-like members are subjected to insulation treatment on the build-up layer. For example, the linear motor of claim 5 in which the movable member has a holding member for holding the magnet array, and the holding member has a plurality of holes into which each of the plurality of permanent magnets is inserted. For example, the linear motor of item 8 of the patent application scope, wherein the movable element has the holding member and a plate-like bottom material for fixing and fixing the plurality of permanent magnets.