TW201840105A - Linear motor - Google Patents

Abstract

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

Description

Linear motor

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

Conventionally, in the X and Y movements, a method of converting the output of the rotary motor into a linear motion by a ball screw has been used. However, since the moving speed is slow, development of a linear motor that can directly take out linear motion output is developed. A linear motor is generally constructed by combining a movable body having a plurality of rectangular permanent magnets with an armature having a plurality of magnetic pole teeth.

Further, since the bonding wire and the crystal carrier of the processing machine of the semiconductor manufacturing apparatus require high-speed reciprocating motion, it is preferable to use a linear motor having 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 movable member is opposed to the entire surface of the armature as a stator, but is formed in a movable body. A linear motor in which the length of the permanent magnets is shorter than the length of the armature.

The linear motor has a configuration in which a movable member and an armature are opposed to each other via a gap, and the movable sub-system has a magnet array in which a plurality of permanent magnets are arranged, and a flat back yoke integrated with the magnet. The armature winds the drive coils around a plurality of magnetic pole teeth. By energizing the drive coil, the movable member (magnet arrangement and back yoke) moves, and the difference between the length of the movable member and the armature becomes an operable stroke of the linear motor.

When the yoke and the magnet are arranged to form a movable member after being formed of a ferromagnetic body, a suction force is generated between the opposing stators. Due to the suction generated, a large vertical resistance acts on the bearing that supports the movable member to be movable in a predetermined direction. This vertical resistance causes the short life of the bearing. Further, the direction in which the vertical resistance acts is a direction in which the movable direction of the movable member intersects. Therefore, it is necessary to select the bearing under consideration of the vertical resistance. Therefore, it becomes a bearing that is larger than the bearing that is selected according to the load caused by the movable member. This leads to an increase in the size of the linear motor as a whole.

Therefore, a linear motor (Patent Documents 3 to 5, etc.) which is different from the linear motor described above is proposed, and only the magnets are arranged to act as a movable member, and the back yoke acts as a linear motor of the stator.

In such a linear motor, the magnet array is separated from the flat back yoke, and the back yoke and the magnet are arranged to face each other with the interval on the side opposite to the armature, so that only the magnet array can be moved. Only the magnets are arranged to move, 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 in length becomes the actionable stroke of the linear motor. [Prior patent documents] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. WO-A-2005-159034 (Patent Document 3) Japanese Laid-Open Patent Publication No. 2005-117856 (Patent Document 4) JP-A-2015- Publication No. 130754 [Patent Document 5] Japanese Patent Laid-Open Publication No. 2005-184984

[Problems to be solved by the invention]

The movable subsystem is strongly attracted to the magnetic tooth flanks of the armature. The suction force F at this time is expressed in accordance with the following mathematical expression. F=B ² S/2μ ₀ (where B: the magnetic flux density on the magnetic pole teeth of the armature, S: the relative effective area of the movable element and the armature, μ ₀ : the magnetic permeability of the vacuum)

A linear motor (integrated linear motor: Patent Document 1 or 2) having a movable body in which a magnet array is integrated with a flat back yoke, and the suction force is several times to ten times or more of the normal rated thrust. Therefore, there is a problem that the movable body is warped due to a large suction force. As a result, the dimensional accuracy of the processing machine using such a warped linear motor is deteriorated. Further, it is necessary to increase the rigidity of the movable member, and it is disadvantageous in that the configuration is increased in size.

Since the excessive suction force also affects the linear guide that supports the movable member, in order to withstand such excessive suction force, the linear guide rail requires a large rated load, and the enlargement of the configuration cannot be avoided at this point. Therefore, it is preferable to reduce the suction force as shown above. However, in order to reduce the suction force, it is necessary to make a small structure and generate a large thrust in advance.

Further, in the integrated linear motor, the cogging torque is increased due to a large edge effect, and the starting torque is large.

A linear motor (separate type linear motor: Patent Documents 3 to 5, etc.) in which the magnet array is separated from the flat back yoke and the magnets are arranged to move, because the suction force acts on the magnet from both the back yoke and the armature. Arranged, so the overall suction force becomes smaller than the integrated linear motor. However, in the split type linear motor, the area of the magnetic pole facing the magnet array is approximately the same area as the total magnet area on the back yoke side with respect to the area of the magnetic pole teeth facing the armature side. 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, so that 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 made small, so that the suction force of the magnet array and the back yoke is reduced to the same extent as the suction force between the magnet array and the armature. However, in the case where the gap between the magnet array and the back yoke is widened, since the magnetic flux density from the armature for generating the thrust is also reduced, there is a problem that the thrust force is small. Therefore, the split type linear motor proposed so far has a problem that the thrust force cannot be prevented from being reduced in order to reduce the suction force acting on the movable member.

Further, in the split type linear motor, as described above, since the suction force between the movable member (magnet arrangement) and the stator (armature) and the suction force of the movable member and the back yoke are substantially the same size and reversed, The suction acting on the movable member can be reduced. 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 magnet arrangement. An increase in the eddy current causes heat to be generated. 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 of a workbench of a semiconductor manufacturing device.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a linear motor capable of reducing the suction force and reducing the starting torque while achieving a small configuration and generating a large thrust.

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

The linear motor of the present invention is characterized in that: a movable member is a magnet arrangement having a plurality of rectangular permanent magnets; a stator back yoke is disposed opposite to the movable body via a gap; and an armature as a stator, Separating the movable member with the gap on the side opposite to the back yoke; the magnetization directions of the plurality of permanent magnets are in the thickness direction, and the magnetization directions of the adjacent permanent magnets are opposite; the armature system Having a plurality of magnetic pole teeth each wound with a driving coil at equal intervals; the back yoke is on a surface facing the movable member, and has a plurality of positions at the same position as the magnetic pole teeth of the armature in a movable direction of the movable member a magnetic pole tooth; a magnetic pole area of the magnetic pole tooth of the back yoke is 0.9 to 1.1 times a magnetic pole area of the magnetic pole tooth of the armature, a gap between the movable body and the back yoke, and the movable body and the armature The gaps are equal or relatively large.

In the linear motor of the present invention, the movable motor has a magnet array in which a plurality of permanent magnets are arranged; the back yoke is disposed to face the movable body via a gap; and the armature is interposed between the back and the yoke. The opposite side is disposed opposite to the movable member. The magnets act as a mover, and the back yoke and armature act as a stator. The plurality of rectangular permanent magnets arranged in the magnet are magnetized in the thickness direction, and the magnetization directions are reversed between the adjacent permanent magnets. The armature has a plurality of magnetic pole teeth at equal intervals, and the drive coils are wound around the respective magnetic pole teeth. The surface of the back yoke and the movable body is not a flat plate, but a plurality of magnetic pole teeth are formed at equal intervals. The pitch of the magnetic pole teeth of the back yoke is equal to the pitch of the magnetic pole teeth of the armature, and the position of the magnetic pole teeth of the back yoke is at the same position as the magnetic pole teeth of the armature in the movable direction of the movable body. The magnetic pole area of the magnetic pole teeth of the back yoke is 0.9 times to 1.1 times the magnetic pole area of the magnetic pole teeth of the armature, and the gap between the movable element and the back yoke is more than the gap between the movable arm and the armature.

In the linear motor of the present invention, the back yoke is also provided with magnetic pole teeth having substantially the same magnetic pole area at the same position as the back yoke. In other words, it is configured such that only the back yoke portion to which the driving magnetic flux from the armature is applied approaches the movable member, and the movable member is interposed with a gap other than the portion facing the magnetic pole teeth of the armature. Since the magnetic pole area of the armature opposed to the movable member and the magnetic pole area of the yoke facing the movable body are substantially equal to each other, the mutual efficiency is largely canceled, and the overall suction force is greatly reduced. Therefore, even if the gap between the movable member and the back yoke is not increased, the suction force can be greatly reduced. At this time, since it is not necessary to increase the gap between the movable member and the back yoke, the reduction in thrust is small.

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

In the linear motor of the present invention, since the movable member is disposed between the armature having a plurality of magnetic pole teeth at equal intervals, and the back yoke having a plurality of magnetic pole teeth at the same position as the magnetic pole teeth of the armature in the movable direction With this configuration, the cogging torque of the magnets arranged in the direction perpendicular to the movable direction is reduced, and the starting torque of the movable member can be reduced.

In the case where the magnetic pole area of the magnetic pole teeth of the back yoke is made too large, a large amount of magnetic flux is picked up from the surroundings, and the suction force is increased, and on the other hand, when the magnetic pole area of the magnetic pole teeth of the back yoke is made too narrow, The magnetic flux that gets the thrust is reduced, and the thrust is reduced. Therefore, the magnetic pole area of the magnetic pole teeth of the back yoke is made 0.9 times to 1.1 times the magnetic pole area of the magnetic pole teeth of the armature.

Since the magnetic pole teeth of the armature are wound around the driving coil, the magnetic pole tooth system of the armature is configured to be 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 generated in portions other than the magnetic pole teeth, and the suction force tends to be larger than the armature side. Therefore, in order to perform high-efficiency cancellation of the suction force, the gap between the movable member and the back yoke and the gap between the movable member and the armature are made equal or larger.

The linear motor 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, in the case where the height of the magnetic pole teeth of the back yoke is much smaller than the pitch, the effect of providing the magnetic pole teeth (concavo-convex shape) cannot be obtained, and on the other hand, the height of the magnetic pole teeth of the back yoke is much larger than the pitch. In the case of the same effect, it is not conducive to miniaturization. Therefore, the height of the magnetic pole teeth of the back yoke is made 1/20 times or more and 2 times or less of the distance between the magnetic pole teeth.

The linear motor of the present invention is characterized in that the length of the movable member 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 movable member is shorter than the length of each of the armature and the back yoke. Therefore, it is a small structure and ensures a large acceleration. Further, since the edge effect is small, the cogging torque is reduced, and the starting torque can be reduced.

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

In the linear motor of the present invention, the size of the gap between the movable member and the back yoke and/or the size of the gap between the movable member and the armature are variable. Therefore, the magnitude of the gap between the movable member and the back yoke and/or the size of the gap between the movable member and the armature can be adjusted in accordance with the magnitude of the driving magnetomotive force at the time of use, whereby the suction force can be made almost zero.

The linear motor of the present invention is characterized in that: a movable member is a magnet arrangement having a plurality of rectangular permanent magnets; a stator back yoke is disposed opposite to the movable body via a gap; and an armature as a stator, Separating the movable member with the gap on the side opposite to the back yoke; the magnetization directions of the plurality of permanent magnets are in the thickness direction, and the magnetization directions of the adjacent permanent magnets are opposite; the armature system Having a plurality of magnetic pole teeth each wound with a driving coil at equal intervals; the back yoke is on a surface facing the movable member, and has a plurality of positions at the same position as the magnetic pole teeth of the armature in a movable direction of the movable member a magnetic pole tooth; the magnetic pole tooth of the back yoke is formed by laminating a plurality of plate-like members in a direction crossing the movable direction of the movable member.

In the linear motor of the present invention, by forming the magnetic pole teeth in a laminated structure, the eddy current can be reduced while reducing the suction force acting on the movable member.

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

In the linear motor of the present invention, the yoke system has a laminated structure from a portion in the thickness direction from the connecting portion with the magnetic pole teeth, whereby the eddy current can be further reduced. Further, since the plate-like member constituting the laminated portion of the back yoke is integrated with the plate-like member constituting the magnetic pole teeth, the number of manufacturing steps is reduced.

The linear motor of the present invention is characterized in that the plurality of plate-like members are subjected to an insulating treatment on the laminate.

In the linear motor of the present invention, since a plurality of plate-like members apply an insulating treatment to the laminate, the eddy current can be further reduced.

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

In the linear motor of the present invention, the magnet arrangement (a plurality of permanent magnets) is held by the holding member. Therefore, since the rigidity of the movable member (magnet arrangement) is increased, deformation of the permanent magnet such as warpage or bending is less likely to occur, and the starting torque can be reduced.

The linear motor of the present invention is characterized in that the movable sub-system has the holding member and a plate-shaped base material to which the plurality of permanent magnets are adhered and fixed.

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

In the linear motor of the present invention, the suction force acting on the movable member (magnet arrangement) can be greatly reduced and the starting torque of the movable member can be reduced while achieving a small configuration and generating a large thrust. Therefore, the deformation caused by the warpage accompanying the large suction force can be suppressed, and the deterioration of the dimensional accuracy of the device using the linear motor can be prevented. Since the suction force can be made small, the rigidity of the movable member and the rigidity of the support system supporting the movable member can be made small, and not only the miniaturization can be achieved, but also the acceleration can be improved by the weight reduction of the movable mass. Further, since the magnetic pole tooth structure is provided to the back yoke, since the thrust from the back yoke is added to the movable body, the gap is provided between the magnet array and the back yoke to minimize the reduction in thrust caused.

Further, in the linear motor of the present invention, the eddy current can be suppressed while reducing the suction force acting on the movable member (magnet arrangement).

Hereinafter, the present invention will be described in detail based on the drawings showing embodiments of the present invention. (First embodiment)

Fig. 1 and Fig. 2 are a perspective view and a side view showing the configuration of the linear motor 1 of the first embodiment. 3 and 4 are a plan view and an exploded perspective view showing the configuration of the movable member 2 of the linear motor 1 according to the first embodiment. Further, in the first and second figures, only the movable member 2 indicates a cross section in a direction parallel to the movable direction in order to know the arrangement of the magnets.

The linear motor 1 includes a movable member 2, a back yoke 3, and an armature 4. The back yokes 3 are disposed to face each other with a gap therebetween, and the armatures 4 are disposed to face each other with a gap between the movable members 2 on the side opposite to the back yokes 3 . The back yoke 3 and the armature 4 function as a stator.

As shown in FIG. 4, the elongated movable member 2 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 member 2. Each of the permanent magnets 21 is formed in a rectangular shape. Each of the permanent magnets 21 is, for example, a Nd—Fe—B based rare earth magnet. Each of the permanent magnets 21 is magnetized in the thickness direction (the lower direction in the second drawing), and the magnetization direction is reversed between the adjacent permanent magnets 21 and 21. In other words, the magnets are arranged alternately in the permanent magnet 21 magnetized in the direction from the back yoke 3 side toward the armature 4 side, and the permanent magnet 21 magnetized in the direction from the armature 4 side to the back yoke 3 side.

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 the thickness 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 of the permanent magnets 21 is fitted into the hole 221 and fixed to the holding frame 22 with an adhesive. The holes 221 are provided to be fixed to the permanent magnets 21 of the holding frame 22 in parallel at equal intervals. Moreover, when the permanent magnet 21 is fixed to the holding frame 22, the magnetization direction in which the holes 221 are fitted between the adjacent permanent magnets 21 and 21 is reversed. As shown in Fig. 3, each of the permanent magnets 21 is arranged obliquely at a caution angle θ.

In a state in which a 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. Further, 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 manner, since the magnet array is held by the holding frame 22 and adhered to the fixing plate 23, the rigidity of the movable member 2 is high, and the permanent magnet 21 does not fall off. The movable member 2 is disposed in the gap between the back yoke 3 and the armature 4 such that the fixed plate 23 faces the back yoke 3. Further, the fixing plate 23 is not essential, and it is not necessary to sufficiently hold the permanent magnet 21 by the holding frame 22.

The lengths of the back yoke 3 and the armature 4 in the movable direction (the horizontal direction in the second drawing) are substantially equal, and the length of the movable member 2 in the movable direction (the horizontal direction in the second drawing) is proportional to the back yoke 3 and The length of the armature 4 is shorter, and the difference in length becomes the operable stroke of the linear motor 1, by which the edge effect is reduced.

It is a flat plate shape of the back yoke 3 which is preferably made of a soft magnetic material (for example, a ruthenium steel plate) and which does not face the movable member 2, but the surface of the back yoke 3 opposite to the movable body 2 It is not a flat plate shape, and is formed in a plurality of rectangular magnetic pole teeth 31 at equal intervals in the movable direction. The height of each of the magnetic pole teeth 31 is 1/20 times or more and 2 times or less of the pitch of the magnetic pole teeth 31, and preferably 1/10 times or more and 1 time or less. For example, the height of each of the magnetic pole teeth 31 is about half of the pitch of the magnetic pole teeth 31.

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

The pitch of the magnetic pole teeth 31 of the back yoke 3 is equal to the pitch of the magnetic pole teeth 42 of the armature 4, and the position of the magnetic pole teeth 31 of the back yoke 3 is in the movable direction of the movable member 2 and the magnetic pole teeth 42 of the armature 4. The same location. Further, the shape of the magnetic pole tooth 31 of the back yoke 3 and the magnetic pole surface facing the movable member 2 are formed into a rectangular shape having substantially the same shape as the magnetic pole surface of the magnetic pole tooth 42 of the armature 4 facing the movable member 2, the former The magnetic pole area is 0.9 to 1.1 times the magnetic pole area of the latter. For example, the magnetic pole faces of the magnetic pole teeth 31 and the magnetic pole faces of the magnetic pole teeth 42 have the same rectangular shape and have the same area. Further, the gap between the movable member 2 and the back yoke 3 and the gap between the movable member 2 and the armature 4 are equal or larger. For example, the latter has a gap of 0.5 mm and the former has a gap of 0.5 mm or more. Even in this case, the gap between the movable member 2 and the back yoke 3 is configured to include the fixing plate 23, and the thickness of the fixing plate 23 is not included, and the distance between the movable member 2 itself and the back yoke 3 (the shortest distance) is shown. In other words, this gap is a magnetic gap (magnetic gap), and it is not necessary to consider the thickness of the non-magnetic fixing plate 23.

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

In the linear motor 1 of the first embodiment, the magnetic pole teeth 31 are formed on the surface of the back yoke 3 facing the movable member 2, and the magnetic pole teeth 31 are the same as the magnetic pole teeth 42 of the armature 4 in the movable direction. The magnetic pole faces having substantially the same shape are located, and the magnetic pole areas are substantially equal. Therefore, the magnitude of the suction force generated between the movable member 2 and the back yoke 3 and the magnitude of the suction force generated between the movable member 2 and the armature 4 become substantially equal to each other in the lower direction on the second drawing. The suction force is effectively canceled, so that the suction force of the linear motor 1 acting on the movable member 2 as a whole becomes small. In this manner, in the linear motor 1 of the first embodiment, the suction force can be greatly reduced without increasing the gap between the movable member 2 and the back yoke 3. Therefore, since it is not necessary to increase the gap between the movable member 2 and the back yoke 3, the reduction in thrust does not occur.

Further, in the linear motor 1 of the first embodiment, as described above, the armature 4 having the plurality of magnetic pole teeth 42 at equal intervals and the magnetic pole teeth 42 of the armature 4 are in the same movable direction. Since the configuration of the movable member 2 is disposed between the back yokes 3 having a plurality of magnetic pole teeth 31, the cogging torque of the magnet array in the direction perpendicular to the movable direction is reduced, and the start of the movable member 2 can be reduced. Torque. Further, since the magnet array is 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 warpage and bending of the permanent magnet 21 is hard 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 in the back yoke 3, and since the concave and convex shape opposed to the movable member 2 generates a cutting region for driving the magnetic flux, 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 the magnetic flux of the linear motor 1 of the first embodiment. In Fig. 5, the arrow indicates the flow of the magnetic flux. In the linear motor 1, the thrust is generated by the cutting of the magnetic flux on the armature 4 side, and the thrust by the magnetic flux on the side of the back yoke 3 also generates the thrust, and the thrust generated by the linear motor 1 becomes the two thrusts. with. Further, in the linear motor in which the magnetic pole teeth 31 are not formed as in the first embodiment and the back yoke is in the form of a flat plate, no thrust is generated on the back yoke side, and only the magnetic flux by the armature 4 side is cut. The thrust.

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

From the above, the linear motor 1 of the first embodiment is used. The suction force acting on the movable member 2 can be greatly reduced while maintaining a large thrust. Therefore, the warp of the suction force is hardly generated in the movable member 2, and the dimensional accuracy of the processing machine or the like in the semiconductor manufacturing apparatus using the linear motor 1 becomes high.

Further, in the linear motor 1 of the first embodiment, it is possible to use the permanent magnet 21 and the holding frame 22 which are small in rigidity. Therefore, the movable member 2 can be miniaturized, and a large acceleration can be realized with the weight reduction of the movable member 2. Moreover, since the wear of the movable member 2 is also small, the life of the linear motor 1 can be made long.

In the linear motor, in order to smoothly move the movable member, as will be described later, the linear guide is generally provided on the side surface of the movable member. However, in the linear motor 1 of the first embodiment, since the suction force is small, the linear guide can be used. This is also a small rigidity, which also contributes to the miniaturization and longevity of linear motors.

In the linear motor 1 of the first embodiment, the length of the movable member 2 is made shorter than the length of the back yoke 3 and the armature 4, so that further miniaturization, weight reduction, and speed increase can be achieved.

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

First, the mover 2 is made. From the Nd-Fe-B rare earth magnet (B _r = 1.395T, H _cJ = 1273 kA/m), 14 permanent magnets 21 having a thickness of 5 mm, a width of 12 mm, and a length of 82 mm were cut out. The cut permanent magnet 21 is excited in the thickness direction. Next, the holding frame 22 as shown in Fig. 4 was cut by wire cutting from a SUS plate having a thickness of 3 mm. The cut holding frame 22 is adhered and fixed to a fixing plate 23 made of a SUS plate having a thickness of 0.2 mm. Then, the 14 permanent magnets 21 to which the adhesive is applied are given an inclination angle θ=3.2 ∘ and embedded in the hole 221 of the holding frame 22 so that the magnetization directions of the adjacent permanent magnets 21 become opposite to each other, and the permanent magnets are inserted. 21 is adhesively fixed to the holding frame 22 and the fixing plate 23. Here, in order to achieve both the weight reduction of the movable member 2 and the rigidity of the magnet array, the thickness of the holding frame 22 is set to 3 mm with respect to the thickness of the permanent magnet 21 of 5 mm.

Further, unlike the above-described example, the holding frame 22 may be formed by a method in which a SUS plate having a thickness of 0.5 mm is overlapped by a press-worked hole and fixed by a gap filling process. In this case, the plan is to reduce the production costs.

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

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

Then, the armature 4 is produced. Fig. 7 is a plan view showing an armature material used for fabricating the armature 4 of the linear motor 1 of the first embodiment. From the 矽 steel plate (JIS Standard C2552 type mark 50A800 material) having a thickness of 0.5 mm, 164 pieces of armature material 44 having a shape as shown in Fig. 7 were cut, and the cut 164 pieces were overlapped and made by CO ₂ laser. The side surface is melted into one body, and a block having a width of 82 mm, a height of 31 mm, and a length of 263.04 mm (having 18 equally spaced magnetic pole teeth 42 at a pitch (15.12 mm) of the core 41 (width: 6 mm, height: 25 mm, length: 82 mm, magnetic pole area 492 mm ² ).

Next, the winding is inserted into this block. Fig. 8 is a view showing the winding of the armature 4 of the linear motor 1 of the first embodiment. The enamel coated wire having a diameter of 2 mm was wound for 17 turns and immersed in a varnish and fixed to the arm portions of the respective magnetic pole teeth 42 of the armature 4, whereby the drive coil 43 was formed.

U, V, and W in Fig. 8 show the U phase, V phase, and W phase of the three-phase AC power supply, respectively, and the coil systems of the respective phases are connected in series. When the U coil, the V coil, and the W coil are wired, the current flows in the clockwise direction when viewed from above, and the -U coil, the -V coil, and the -W coil are wired so that the current flows in the counterclockwise direction when viewed from above. Make armature 4. Further, each of the six U coils, the V coil, the W coil, the -U coil, the -V coil, and the -W coil is star-connected, and is connected to a three-phase AC power supply.

Then, the manufactured back yoke 3 and the armature 4 were fixed using a jig to maintain the interval between the two at a fixed 6 mm. Further, the gap between the back yoke 3 and the armature 4 is fixed to be 6 mm, but this gap is used to adjust the structure after assembling the linear motor 1. Next, after the linear guide (not shown) is attached to the side surface of the movable member 2, the movable body 2 having a thickness of 5 mm is inserted into the back yoke 3 and the armature so as to be spaced apart from the back yoke 3 and the armature 4 by a predetermined distance. With a gap of 4, a linear motor 1 was fabricated. At this time, the distance between the movable member 2 and the magnetic pole teeth 31 of the back yoke 3 and the distance between the movable member 2 and the magnetic pole teeth 42 of the armature 4 are both 0.5 mm. Further, in order to measure the suction force, the load cell is disposed between the linear guide and the armature 4.

Since the structure in which the gap between the back yoke 3 and the armature 4 can be adjusted is formed, the distance between the movable member 2 and the armature 4 (magnetic pole teeth 42) can be fixed, and the movable member 2 and the back yoke can be arbitrarily set. The distance between the gaps of 3 (magnetic pole teeth 31) is made adjustable. Further, the distance between the movable member 2 and the back yoke 3 (magnetic pole teeth 31) and the movable member 2 and the armature can be adjusted by adjusting the insertion position of the movable member 2 for the gap between the back yoke 3 and the armature 4. The ratio of the distances of the gaps of 4 (magnetic pole teeth 42) is set to a desired value.

Further, as a mechanism for adjusting the gap between the armature 4 and the linear guide supporting the movable member 2 and between the armature 4 and the back yoke 3, a mechanism for adjusting the height by inserting the gap adjusting screw or a screw insertion sectional shape may be employed. Become a tapered shim plate to adjust the height of the mechanism.

Figs. 9A and 9B are views showing a configuration of a linear motor 1 according to an example of the first embodiment produced in this manner, and Fig. 9A is a top view thereof, and Fig. 9B is a side view thereof. In Fig. 9B, the blank arrow indicates the magnetization direction of the permanent magnet 21, and the solid arrow indicates the movable direction of the movable member 2. Moreover, 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-based rare earth magnet (NMX-S49CH material made of Hitachi Metal) Shape of permanent magnet 21: thickness 5.0 mm, width 12 mm, length 82 mm permanent magnet 21 Distance: 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) Magnetic pole tooth 31 Shape: width: 6.0 mm, height: 3.0 mm, length: 82 mm Pitch of magnetic pole teeth 31: 15.12 mm Physique of core 41: height 31 mm, width 82 mm, length 264.04 mm Material of core 41: 矽 steel plate (JIS specification C2552 type mark) 50A800 material) Shape of magnetic pole tooth 42: Width: 6.0 mm, Height: 25 mm, Length: 82 mm Pitch of magnetic pole tooth 42: 15.12 mm Shape of drive coil 43: Width: 15.12 mm, Height: 23 mm, Length: 91.12 mm Drive coil Winding thickness of 43: 4.06mm Diameter of winding of driving coil 43 and number of turns: diameter 2mm, winding resistance of 17 turns (1): 0.0189Ω Mass of movable 2: 516.6g

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

The shape of the magnetic pole surface of the magnetic pole tooth 31 facing the magnet array and the shape of the magnetic pole surface of the magnetic pole tooth 42 facing the magnet array are rectangular in the same size. In other words, the width (the dimension in the movable direction) of the magnetic pole teeth 31 and the width (the dimension in the movable direction) of the magnetic pole teeth 42 are equal, and both are 6 mm, and the magnetic pole area of the magnetic pole teeth 31 opposed to the magnet array and the magnet arrangement are opposed to each other. The magnetic pole areas of the magnetic pole teeth 42 are equal, both of which are 492 mm ² .

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

Fig. 10 is a graph showing the thrust fluctuation of the electric angle of the linear motor 1 according to an example of the first embodiment. This thrust variation indicates the thrust of the position of the movable member 2 in the case where the driving magnetomotive force (= the magnitude of the driving current × the number of turns of the driving coil 43) is regarded as 1200 A (U phase, V phase, and W phase 3) Phase synthesis thrust) changes. In Fig. 10, the horizontal axis is the electrical angle [∘], and the vertical axis is the thrust [N]. Further, in Fig. 10, a indicates the thrust by the armature 4, and in Fig. 10, b indicates the thrust by the back yoke 3, and in Fig. 10, c indicates the overall thrust (by the thrust of the armature 4 and the borrowing The sum of the thrusts of the yokes 3). As shown in Fig. 10, it is known that a substantially constant thrust can be obtained over the entire area.

Fig. 11 is a graph showing the thrust characteristics of the linear motor 1 according to 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 drives the magnetomotive force [A], the left vertical axis is the thrust [N], and the right vertical axis is the thrust magnetomotive force ratio [N/A]. Further, in Fig. 11, a represents the thrust, and in Fig. 11, b represents the thrust magnetomotive force ratio. In this linear motor 1, the thrust proportional limit (the thrust magnetomotive force ratio is reduced by 10%) is 1000 N when the driving magnetomotive force is 1200 A.

Fig. 12 is a graph showing the suction characteristics of the linear motor 1 of 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 drives the magnetomotive force [A], and the vertical axis shows the suction force [N]. Further, the suction system indicates that the movable member 2 is attracted to the + lateral armature 4 side, and the movable member 2 is attracted to the side of the back yoke 3 side. In response to the increase in the driving magnetomotive force, the suction force is gradually increased. For example, in the case where the driving magnetomotive force is 1200 A, the movable member 2 is attracted to the back yoke 3 side with a suction force of about 290 N.

In order to evaluate the linear motor 1 of the first embodiment in comparison with a conventional linear motor, two kinds of linear motors (the first conventional example and the second conventional example) were produced as a conventional example, and those linearities were measured. The characteristics of the motor (thrust and suction).

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

The linear motor 50 of the first conventional example has a movable member 51 in which the magnet array 52 and the back yoke 53 are integrated, and an armature 54 that is disposed to face the movable member 51 with the gap interposed 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 in which the magnets of the movable member 2 described above are arranged. In other words, the magnet array 52 is formed by fixing a plurality of rectangular permanent magnets 55 at a constant pitch to a non-magnetic holding frame, and is formed in a movable direction (left-right direction of FIG. 13), and each permanent magnet 55 is provided. It is magnetized in the thickness direction (downward direction in Fig. 13), and its magnetization direction is reversed between adjacent permanent magnets 55, 55. In the linear motor 50 of the first conventional example, the magnet array 52 is adhered to the flat yoke 53 of a soft steel. Further, the configuration of the armature 54 is the same as that of the above-described armature 4, and a plurality of magnetic pole teeth 57 are integrally provided to the core 56 at equal intervals in the movable direction, and the drive coil 58 is wound around the magnetic pole teeth 57. .

Figs. 14A and 14B are views 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, the blank arrow indicates the magnetization direction of the permanent magnet 55, and the solid arrow indicates the movable direction of the movable member 51. Further, the size of the gap between the movable member 51 and the armature 54 is made 0.5 mm or 1 mm. The details of the manufacturing specifications of this linear motor 50 are as follows.

Magnetic pole structure: 7-pole 6-slot permanent magnet 55 Material: Nd-Fe-B-based rare earth magnet (NMX-S49CH material made of Hitachi Metal) Shape of permanent magnet 55: thickness 5.0 mm, width 12 mm, length 82 mm permanent magnet 55 Distance: 12.96mm Tilt angle of permanent magnet 55: 3.2∘ Shape of back yoke 53: thickness 6.0mm, width 90mm, length 190mm Material of back yoke 53: mild steel (JIS specification G3101 type mark SS400 material) Physique of core 56: Height 31mm, width 82mm, length 263.04mm Core material: 矽 steel plate (JIS standard C2552 type symbol 50A800 material) Magnetic pole tooth 57 shape: width: 6.0mm, height: 25mm, length: 82mm Pitch of magnetic pole teeth 57: 15.12 Mm Drive coil 58 shape: Width: 15.12 mm, Height: 23 mm, Length: 91.12 mm Winding thickness of drive coil 58: 4.06 mm Diameter of winding of drive coil 58, number of turns: diameter 2 mm, 17-turn winding resistance (1 ()): 0.01189Ω The mass of the movable 51 (magnet arrangement 52 + back yoke 53): 1321.01g

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

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

The linear motor 60 according to the second conventional example has a magnet array 62, a back yoke 63 that is disposed to face the magnet array 62 with a gap therebetween, and a magnet argon 62 disposed opposite to the back yoke 63 with a gap interposed therebetween. Armature 64. Only the magnet array 62 acts as a mover, and the back yoke 63 and the armature 64 act as a stator.

The configuration of the magnet array 62 is the same as the configuration in which the magnets of the movable member 2 described above are arranged. In other words, the magnet array 62 is configured such that a plurality of rectangular permanent magnets 65 are fixed to the non-magnetic holding frame at equal intervals, and are formed in a movable direction (left-right direction of FIG. 15). Each of the permanent magnets 65 is provided. It is magnetized in the thickness direction (downward direction in Fig. 15), and its magnetization direction is reversed between adjacent permanent magnets 65, 65. The yoke 63 of the mild steel is not only a surface that does not face the magnet array 62, but also a flat 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. . Further, the configuration of the armature 64 is the same as that of the above-described armature 4, and a plurality of magnetic pole teeth 67 are integrally provided to the core 66 at equal intervals in the movable direction, and the drive coil 68 is wound around the magnetic pole teeth 67. .

Figs. 16A and 16B are views showing the configuration 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, the blank arrow indicates the magnetization direction of the permanent magnet 65, and the solid arrow indicates the movable direction of the magnet array 62 (movable). Further, the size of the gap between the magnet array 62 and the back yoke 63 and the size of the gap between the magnet array 62 and the armature 64 are both 0.5 mm. Further, 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-based rare earth magnet (NMX-S49CH material made of Hitachi Metal) Shape of permanent magnet 65: thickness 5.0 mm, width 12 mm, length 82 mm permanent magnet 65 Distance: 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: Height 31 mm, width 82 mm, length 264.04 mm Core 66 material: 矽 steel plate (JIS standard C2552 type symbol 50A800 material) Magnetic pole tooth 67 shape: width: 6.0 mm, height: 25 mm, length: 82 mm Pitch of magnetic pole teeth 67: 15.12 Mm Drive coil 68 shape: Width: 15.12mm, Height: 23mm, Length: 91.12mm Winding thickness of drive coil 68: 4.06mm Winding diameter of drive coil 68, number of turns: diameter 2mm, 17-turn winding resistance (1 ()): 0.01189 Ω movable mass (magnet arrangement 62) mass: 516.6g

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

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

Fig. 17 is a graph showing the average thrust of the linear motor in the first conventional example, the second conventional example, and the first embodiment. Fig. 17 is a graph showing the average thrust [N] in the case where the driving magnetomotive force is set to 1200A. In addition, Fig. 18 is a graph showing the average suction force of the linear motor in the first conventional example, the second conventional example, and the first embodiment. Fig. 18 is a graph showing the average suction force [N] in the case where the driving magnetomotive force is set to 1200A. Here, the average thrust and the average suction force are measured (calculated) at a distance of 15 从 from the U-phase electric angle of 0 ∘ to 360 推力 at an interval of 15 推力, and the suction force is extracted at 25 points, and the average value is calculated.

In the first and third embodiments of the magnet array 52 and the back yoke 53, a linear motor 50 having a gap of 0.5 mm between the movable member 51 and the armature 54 (hereinafter also referred to as linear) is shown in Figs. The motor 50A), B is a linear motor 50 (hereinafter also referred to as a linear motor 50B) in which the gap between the movable member 51 and the armature 54 is 1 mm in the first conventional example of the magnet array 52 and the back yoke 53. In the second conventional example in which the magnet array 62 and the back yoke 53 are separated, a gap between the magnet array 62 and the armature 64 and a gap between the magnet array 62 and the armature 64 are 0.5 mm. The linear motor 60 is used. The magnetic pole tooth 31 is formed as an example of the first embodiment of the back yoke 3 separated from the movable member 2 (magnet arrangement), and the gap between the movable member 2 and the back yoke 3 and the gap between the movable member 2 and the armature 4 are 0.5. Linear motor 1 of mm.

In the linear motor 50A (A in the figure) of the first conventional example, although the maximum thrust is 1030 N, the suction force is 4200 N, which is a value which is about four times the thrust. In the linear motor 50B (B in the figure) as a countermeasure for reducing this suction force, the relative thrust is remarkably lowered to 909 N, and the suction force is 3360 N, which is not lowered. Therefore, understanding has not become a sufficient countermeasure.

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

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

Further, in the linear motor 1 of the first embodiment, as shown in Fig. 12, the magnitude of the suction force varies depending on the magnitude of the driving magnetomotive force. Therefore, if the thrust region (driving magnetomotive force) which is often used is used, the size of the gap between the movable member 2 and the back yoke 3 is adjusted, and the suction force can be made smaller.

In an example of the first embodiment described above, the gap between the movable member 2 and the back yoke 3 and the gap between the movable member 2 and the armature 4 are equal to 0.5 mm. However, in another example of the first embodiment, the movable member is movable. The gap between the 2 and the armature 4 is still 0.5 mm, and the gap between the movable member 2 and the back yoke 3 is made 0.74 mm. Further, other configurations are the same as those of the above-described example.

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

In another example, in the case where the driving magnetomotive force is 1200 A, the thrust system is 978 N, which is slightly inferior to the above example. However, as for the suction force, when the driving magnetomotive force is 1200 A, only 18 N can be achieved, and almost zero can be realized. This is a suction that neglects the level of deformation or life reduction caused by the suction of the linear guide or the movable or peripheral structure. Therefore, it is known that the linear motor 1 of another example is suitable for the purpose of reducing the suction force in the case where the driving magnetomotive force of about 1200 A is used.

Further, as another example of the first embodiment, the linear motor 1 in which the gap between the movable member 2 and the armature 4 is still 0.5 mm and the gap between the movable member 2 and the back yoke 3 is 0.66 mm is produced. Further, other configurations are the same as those of the above-described example.

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

Further, in another example, when the driving magnetomotive force is 1200 A, the thrust system is 984 N, which is slightly inferior to the above-described example. However, as for the suction force, when the driving magnetomotive force is 600 A, only 5 N can be achieved, and almost zero can be realized. It is known that the driving magnetomotive force of about 600 A is used, and the linear motor 1 of another example is most suitable for reducing the suction force.

From the above matters, the optimum size of the gap between the movable member 2 and the back yoke 3 is set in accordance with the use region where the frequency is high, and 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 warpage of the movable member 2 (magnet arrangement), reduction in life due to excessive load on the linear guide rail, and the like.

Further, in the above-described embodiment, the case where the size of the gap between the movable member 2 and the armature 4 is fixed and the size of the gap between the movable member 2 and the back yoke 3 is changed is described. However, the movable movable member 2 may be used instead. An example in which the size of the gap between the movable member 2 and the armature 4 is changed by the size of the gap of the back yoke 3, and an example in which the position of the movable yoke 2 is changed by the size of the gap between the fixed yoke 3 and the armature 4 is also changed. A suction force close to zero can be achieved.

Further, in the above-described form, the linear motor 1 in which the movable member 2 is shorter than the armature 4 has been described. However, the linear motor having a configuration in which the movable member is longer than the armature is also a feature of the present invention ( The formation of magnetic pole teeth in the back yoke is applicable. (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. Further, in Fig. 23 and Fig. 24, in order to understand only the arrangement of the magnets by the movable member 2, the cross section in the direction parallel to the movable direction is shown.

The linear motor 1 of the second embodiment includes the movable member 2, the back yoke 3, and the armature 4 as in the first embodiment, and the back yoke 3 and the armature 4 function as a stator.

In addition, the configuration of the movable member 2 and the armature 4 of the linear motor 1 of the second embodiment is the same as that of the movable member 2 and the armature 4 of the linear motor 1 of the first embodiment. Therefore, 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 bottom plate 32. The bottom plate 32 is formed in a rectangular shape. The magnetic pole teeth 31 are fixed to the bottom plate 32. The magnetic pole teeth 31 are fixed such that a part thereof protrudes from the bottom plate 32. The shape of the protruding portion is a rectangular parallelepiped shape. A plurality of magnetic pole teeth 31 are arranged at equal intervals along the length direction of the bottom plate 32. The magnetic pole teeth 31 are formed of, for example, a laminated steel sheet as described later. The bottom plate 32 is formed of, for example, carbon steel such as SS400.

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

As shown in Fig. 24, the lengths of the back yoke 3 and the armature 4 in the movable direction (the horizontal direction in Fig. 24) are substantially equal. Further, the pitch of the magnetic pole teeth 31 of the back yoke 3 is equal to the mutual moment of the magnetic pole teeth 42 of the armature 4. The position of each of the magnetic pole teeth 31 of the back yoke 3 is the same as the position of each of the magnetic pole teeth 42 of the armature 4 in the movable direction of the movable member 2. Further, the magnetic pole faces of the magnetic pole teeth 31 and the magnetic pole faces of the magnetic pole teeth 42 have the same rectangular shape and have the same area. Further, the gap between the movable member 2 and the back yoke 3 and the gap between the movable member 2 and the armature 4 are substantially equal.

In the movable member 2, the magnetization directions of the adjacent permanent magnets 21, 21 are reversed. When the movable member 2 is disposed in the gap between the back yoke 3 and the armature 4, the permanent magnet 21 that is magnetized in the direction from the back yoke 3 side toward the armature 4 side and the rear yoke from the armature 4 side are alternately arranged. The structure of the permanent magnet 21 magnetized in the direction of the 3 side.

At the time of the operation of the linear motor 1, a suction force is generated between the magnetic pole teeth 31 of the back yoke 3 and the permanent magnet 21 of the movable member 2. Further, a suction force is also generated between the magnetic pole teeth 42 of the armature 4 and the permanent magnets 21 of the movable member 2. The two suction systems acting on the movable member 2 are opposite to each other. By adjusting the equal magnetic path in which the magnetic pole faces of the magnetic pole teeth 31 and the magnetic pole faces of the magnetic pole teeth 42 are formed in the same rectangular shape or the same area, the magnitude of the suction force can be made substantially equal. Thereby, 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 can be balanced. That is, the two kinds of suction forces can be canceled each other. Further, in the case where it is difficult to balance the two types of suction due to a machining error, an assembly error, or the like, the interval between the magnetic pole teeth 31 and the permanent magnet 21 or the distance between the magnetic pole teeth 42 and the permanent magnet 21 is adjusted to balance the two kinds of suction forces.

As described above, since the linear motor 1 of the second embodiment has the same configuration as that of 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, the suction force acting on the movable member 2 can be greatly reduced while maintaining a large thrust. Further, in the linear motor 1 of the second embodiment, similarly to the linear motor 1 of the first embodiment, the starting torque of the movable member 2 can be reduced.

Hereinafter, the configuration of the back yoke 3 which is the feature of the second embodiment will be described in detail. Fig. 25 is a perspective view showing a configuration example of the magnetic pole teeth 31 included in the back yoke 3. The magnetic pole teeth 31 are formed in a T-shaped cross section, and have two projecting portions 31a and 31a projecting in the short side direction from the bottom portion (the lower side in Fig. 25). (Therefore, in the twenty-fifth diagram, the H-shaped shape is formed) the protruding portions 31a and 31a are engaged with the concave portions 32a and 32a of the dovetail groove 321 which will be described later. When the linear motor 1 is operated, the short-side direction of the magnetic pole teeth 31 is a direction parallel to the movable direction of the movable member 2.

The magnetic pole teeth 31 are formed by laminating the magnetic pole pieces 311. The pole piece 311 includes a protruding portion 311a for engagement formed by cutting out one of the rectangular plate-like portions. The pole piece 311 is formed of a thin plate of soft magnetic ore steel or the like. The fixing of the laminated pole pieces 311 to each other is performed by heat welding or caulking. In the case of heat welding, for example, first, a layer of a thermosetting adhesive or a film having a heat-fusible property is applied to the surface of the pole piece 311, and then the plate surface is heated while applying pressure thereto. The magnetic pole pieces 311 are fixed by heating.

Further, the thinner the thickness of the pole piece 311 constituting the magnetic pole teeth 31, that is, the more the number of the pole pieces 311 is increased, the more the eddy current loss is reduced. When considering the strength or the labor and time of assembly, the thickness of the pole piece 311 is preferably about 0.2 to 0.5 mm. The number of sheets or the thickness of the pole piece 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 a view in which the vertical direction is reversed from Fig. 24 and Fig. 25 for convenience of explanation. 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 311a of the pole piece 311 (the protruding portion 31a of the magnetic pole tooth 31). The dovetail groove 321 has a concave portion 32a corresponding to the protruding portion 311a (protrusion portion 31a). As shown in Figs. 24 and 25, a plurality of dovetail grooves 321 are formed in the bottom plate 32. A plurality of dovetail grooves 321 are disposed at equal intervals along the movable direction of the movable member 2. The arrangement direction of the plurality of dovetail grooves 321 is a direction parallel to the movable direction of the movable member 2 when the linear motor 1 operates.

Fig. 27 is a partial perspective view showing the back yoke 3. As in the case of Fig. 26, for the sake of convenience of explanation, the upper and lower directions are reversed from those of Figs. 24 and 25. In the back yoke 3, the protruding portion 31a of the magnetic pole tooth 31 is engaged with the dovetail groove 321 .

The fixing of the magnetic pole teeth 31 to the bottom plate 32 is performed, for example, as follows. The adhesive is applied to one or both of the dovetail 321 and the magnetic pole teeth 31. The positioning of the magnetic pole teeth 31 in the dovetail groove 321 is performed using a jig or the like. After the adhesive has hardened, remove the fixture. Further, the fixing method is not limited to this. As long as it can be fixed to the distance between the magnetic pole teeth 31, or the amount of protrusion of the magnetic pole teeth 31 from the bottom plate 32 is within a predetermined error range, other methods are also possible.

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

Next, the reduction of the eddy current will be described. Figure 28 is a partial side view showing the linear motor 1. In Fig. 28, an example of the flow direction of the magnetic flux is indicated by the arrow of the solid line, and an example of the eddy current is indicated by the arrow of the dotted line. As shown in Fig. 28, in the magnetic pole teeth 31, the magnetic flux flows in the downward direction on the paper surface. That is, it flows in a direction parallel to the plate surface of the pole piece 311 constituting the magnetic pole teeth 31. The eddy current is intended to flow in a direction that hinders the change of the magnetic flux in 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 the eddy current is intended to penetrate the direction of the plate surface of the pole piece 311 constituting the magnetic pole teeth 31. However, the magnetic pole teeth 31 are laminated with a plurality of magnetic pole pieces 311, and since the electric resistance between the magnetic pole pieces 311 is large, the eddy current can be reduced. Further, when an insulating film is applied to the surface (surface) of the pole piece 311, the eddy current flowing between the pole pieces 311 can be further reduced.

Fig. 29A and Fig. 29B are diagrams showing an example of the Joule loss caused by the eddy current, Fig. 29A is a graph showing the Joule loss of the linear motor according to the related art, and Fig. 29B is shown in the second embodiment. A graph of the Joule loss of the linear motor 1 of the basic example. The difference between the linear motor according to the related art and the configuration of the linear motor 1 according to the second embodiment is as follows. The former does not have a magnetic pole tooth as a laminated structure. For example, in the former, the magnetic pole tooth is a soft magnetic body block. Alternatively, the bottom plate 32 and the magnetic pole teeth 31 may be integrally formed of a soft magnetic material. On the other hand, the latter magnetic pole teeth 31 have a laminated structure. Other conditions, the structure of the linear motor, the size of the coil, the number of turns of the coil, and the driving conditions are the same. For example, the drive current of the coil is 70.6 A, and the moving speed of the movable body is regarded as 1000 mm/s.

The horizontal axis of the 29A and 29B shows the electrical angle of the position of the movable member 2. The unit degree of the horizontal axis (∘). The longitudinal axis of the 29th and 29th diagrams is the Joule loss caused by the eddy current. The unit is tile (W). The graph of the attached back yoke indicates the Joule loss at the back yoke. As shown in Fig. 29A, in the linear motor according to the related art in which the magnetic pole teeth are not laminated, the Joule loss in the back yoke is about 80 W, and the linear motor in the second embodiment in which the magnetic pole teeth 31 are laminated. 1. The Joule loss at the back yoke 3 is reduced to about 50W.

In Fig. 29A and Fig. 29B, the graphs of U, V, and W are added to indicate the eddy current loss caused by the energization of the U phase, the V phase, and the W phase of the coil, respectively, in absolute values. Further, in Figs. 29A and 29B, the Joule loss in the coil caused by energization of the coil is the same, but there is a large difference in the Joule loss of the back yoke. This result shows an example in which the magnetic pole teeth are not formed in a laminated structure in the same size shape, and the Joule loss due to the eddy current can be reduced in the case where the magnetic pole teeth are formed in a laminated structure, depending on the size of the linear motor or the speed of the linear motor. The absolute value of the Joule loss caused by the eddy current varies, but the percentage of the effect at both of the same speed is maintained.

The linear motor 1 of the second embodiment has the effects as described below. The magnetic pole teeth 31 are formed by laminating magnetic pole pieces 311 formed of a ruthenium steel sheet. Therefore, the direction of the eddy current is the direction through which the plate surface is intended to pass. At this time, due to the gap of the surface of the pole piece 311 or the contact resistance between the pole pieces, the oxide film formed on the surface of the pole piece 311, etc., the resistance in the direction of the eddy current of the magnetic pole teeth 31 becomes a soft magnetic body. The case where the block forms the magnetic pole teeth 31 is large. Therefore, the eddy current flowing to the magnetic pole teeth 31 can be reduced. Further, an insulating treatment for forming a coating of an insulating material or the like may be applied to the surface (layer) of the pole piece 311. In the case where the insulation treatment is applied, the eddy current can be further reduced between the respective steel plates.

Further, in the second embodiment, the magnetic pole teeth 31 of the back yoke 3 are formed in a laminated structure. For example, when a laminated steel plate is formed on the entire back yoke, there is a fear that the rigidity is lowered. In this case, warping can occur in the back yoke 3 due to the suction force generated between the movable member 2. However, in the basic example, only the magnetic pole teeth 31 are formed in a laminated structure, and the bottom plate 32 of the fixed magnetic pole teeth 31 is not formed in a laminated structure. Therefore, the warp of the back yoke 3 is smaller than that according to the related art (the case where the magnetic pole teeth 31 and the bottom plate 32 are formed by the soft magnetic body, or the magnetic pole teeth 31 and the bottom plate 32 are integrally formed by the soft magnetic body) More minor. (First Modification of Second Embodiment)

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

Fig. 31 is a perspective view showing a configuration example of the magnetic pole block 34. The magnetic pole block 34 is formed by laminating a plurality of magnetic pole pieces (plate members) 341. The lamination direction of the magnetic pole piece 341 is a direction intersecting the arrangement direction of the magnetic pole teeth 31, and the magnetic pole piece 341 includes the fitted portion 341a, the connecting portion 341b, and a plurality of protruding portions 341c. The fitted portion 341a has an inverted trapezoidal shape in cross section. The fitted portion 341a is a portion that is the fitted portion 34a of the magnetic pole block 34. The protruding portion 341c has a rectangular cross section. A plurality of protruding portions 341c are formed at equal intervals in the longitudinal direction of the magnetic pole piece 341. The protruding portion 341c is a portion that becomes the magnetic pole tooth 31 of the magnetic pole block 34. The connecting portion 341b is located at a portion between the fitting portion 341a and the protruding portion 341c in the height direction of the magnetic pole piece 341. The connecting portion 341b is connected to a plurality of protruding portions 341c. The pole piece 341 is formed, for example, of a ruthenium plate. The connecting portion 341b is a plate-like member that constitutes a laminated portion that is a part of the bottom portion of the back yoke 3. The protruding portion 341c is a plate-like member that constitutes the magnetic pole teeth 31. The magnetic pole piece 341 is formed by integrating two plate-shaped members.

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

The fitted portion 34a of the magnetic pole piece 34 is fitted into the fitting groove 33a of the bottom portion 33. Further, in the bottom portion 33, the length of the movable member 2 in the movable direction may be set in accordance with the length of the movable direction of the magnetic pole block 34. The fixing of the pair of bottom portions 33 of the magnetic pole block 34 is performed as follows. After the adhesive is applied to one or both of the fitting groove 33a or the fitted portion 34a, the adhesive is fitted. Thereby, the bottom portion 33 and the magnetic pole block 34 are fixed. As a result of the above, the back yoke 3 is formed.

Next, the reduction of the eddy current will be described. Figure 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 the arrow of the solid line, and an example of the eddy current is indicated by the arrow of the dotted line. The reduction of the eddy current in the magnetic pole teeth 31 is the same as the above-described basic example, and thus the description thereof will be omitted. Here, the reduction of the eddy current at the connection portion 341b of the magnetic pole block 34 will be described. As shown in Fig. 33, in the connecting portion 341b, the magnetic flux flows in the left-right direction of the paper surface. That is, it flows in a direction parallel to the plate surface of the magnetic pole piece 341 constituting the magnetic pole piece 34. The eddy current is intended to flow in a direction that hinders the change of the magnetic flux in 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 with the flow direction of the magnetic flux as the axis. The direction of the eddy current is intended to penetrate the direction of the plate surface of the pole piece 341 constituting the magnetic pole block 34. However, the magnetic pole block 34 is formed by laminating a plurality of magnetic pole pieces 341, and since the electric resistance between the magnetic pole pieces 341 is large, the eddy current can be reduced. Further, when an insulating film is applied to the plate surface, the eddy current flowing between the magnetic pole pieces 341 can be further reduced.

Further, the height of the connecting portion 341b will be described. As shown in Fig. 33, the height of the connecting portion 341b is regarded 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 along. Therefore, the magnetic flux does not flow in a portion spaced apart from the magnetic pole teeth 31 by a predetermined value or more. Therefore, the height d of the connecting portion 341b is set so that the magnetic flux in the left-right direction of the paper surface can sufficiently flow. Further, as for the bottom portion 33 where the magnetic flux does not flow, it can be formed of a non-magnetic material. For example, the bottom portion 33 is formed by aluminum or the like having high rigidity and a large Young's modulus. Alternatively, non-magnetic stainless steel or aluminum alloy or the like can be used.

Figs. 34A and 34B are diagrams 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 of the basic example. Figure 34A again reveals Figure 29B. Fig. 34B is a graph showing the Joule loss of the linear motor 1 in the first modification. The magnetic pole tooth 31 has a laminated structure with respect to the basic example, and in the first modification, a part of the magnetic pole tooth and the bottom plate has a laminated structure. Other conditions, the structure of the linear motor, the size of the coil, the number of turns of the coil, and the driving conditions are the same. For example, the drive current of the coil is 70.6 A, and the moving speed of the movable body is regarded as 1000 mm/s.

As shown in Fig. 34A, in the linear motor 1 of the basic example, the Joule loss with respect to the back yoke 3 is about 50 W, and in the linear motor 1 of the first modification, as shown in Fig. 34B, at the back yoke 3 The Joule loss is reduced to approximately 2.5W. Since the connecting portion 341b has a laminated structure, the eddy current caused by the magnetic flux flowing to the connecting portion 341b is also reduced. In Figs. 34A and 34B, the graphs of U, V, and W are respectively expressed as absolute values of eddy current losses caused by energization of the U phase, V phase, and W phase of the coil. Further, in Figs. 34A and 34B, the Joule loss in the coil caused by energization of the coil is the same, but there is a large difference in the Joule loss of the back yoke. This result shows a case where the magnetic pole teeth are formed into a laminated structure in the same size shape, and a part of the magnetic pole teeth and the back yoke is laminated, and the latter can further reduce the Joule loss caused by the eddy current, according to the linearity. The absolute value of the Joule loss caused by the eddy current varies depending on the size of the motor or the speed of the linear motor, but the percentage effect of both at the same speed is maintained.

In the linear motor 1 of the first modification, the magnetic pole block 34 is formed by laminating a ruthenium plate (magnetic pole piece 341). The linear motor 1 has a laminated structure in which a part of the thickness direction is formed not only from the magnetic pole teeth 31 but also from the connection portion of the back yoke 3 and the magnetic pole teeth 31. Therefore, the magnetic flux flowing between the adjacent magnetic pole teeth 31 to the connecting portion 341b is parallel to the surface of the magnetic pole piece 341. The direction of the eddy current generated by the flow of the magnetic flux is the direction of the plate surface to be penetrated by the magnetic pole piece 341. However, the gap in the surface of the magnetic pole piece 341 or the oxide film formed on the surface thereof is larger in the eddy current direction of the connecting portion 341b than in the case where the laminated structure is not formed. 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.

Further, in the first modification, not only the above-described effects of the first basic example but also the following effects are obtained. 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 composed of a material having a large Young's modulus, such as alumina. Therefore, since the rigidity of the entire back yoke 3 is increased, the warpage caused by the suction force generated between the movable yoke 2 and the movable member 2 can be alleviated. Further, depending on the material of the bottom portion 33, the back yoke 3 can be made thinner when the rigidity exceeds the rigidity required for the entire back yoke 3. (Second Modification of Second Embodiment)

The second modification is a configuration in which a part of the bottom plate 32 constituting the back yoke 3 is formed into a laminated structure. Fig. 35 is a side view showing another configuration example of the back yoke 3. The back yoke 3 includes a plurality of back yoke units 301 and a back yoke unit 302. The back yoke unit 301 includes a bottom portion 35 and a magnetic pole tooth unit 36. The back yoke unit 302 includes a bottom portion 35 and a magnetic pole tooth unit 37. The difference between the back yoke unit 301 and the back yoke unit 302 is the difference of the magnetic pole tooth units. One end portion of the back yoke 3 is referred to as a back yoke unit 301, and the other end portion is referred to as a back yoke unit 302. Thereby, as shown in Fig. 35, the back yoke 3 having the magnetic pole teeth 31 at both end portions can be formed.

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

The magnetic pole tooth unit 36 is formed by laminating a plurality of magnetic pole pieces (plate members) 361. The lamination direction of the magnetic pole piece 361 is a direction intersecting the arrangement direction of the magnetic pole teeth 31, and the magnetic pole piece 361 includes the fitted portion 361a, the connecting portion 361b, and a plurality of protruding portions 361c. The fitted portion 361a has an inverted trapezoidal shape in cross section. The fitted portion 361a is a portion of the fitted portion 36a of the magnetic pole tooth unit 36. The protruding portion 361c is formed in a rectangular shape in cross section. A plurality of protruding portions 361c are formed at equal intervals in the longitudinal direction of the magnetic pole piece 361. The protruding portion 361c is a portion that becomes the magnetic pole tooth 31 of the magnetic pole tooth unit 36. The connecting portion 361b is a portion located between the fitting portion 361a and the protruding portion 361c in the height direction of the magnetic pole piece 361. The connecting portion 341b is connected to a plurality of protruding portions 361c. The pole piece 361 is formed, for example, of a ruthenium plate. The connecting portion 361b is a plate-like member that constitutes a laminated portion which is a part of the bottom portion of the back yoke 3. The protruding portion 361c is a plate-like member that constitutes the magnetic pole teeth 31. The pole piece 361 is formed by integrating two plate members.

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

Fig. 37 is a perspective view showing a configuration example of the bottom portion 35. The bottom portion 35 shown in Fig. 37 is an inversion of the top and bottom and the bottom portion 35 shown in Fig. 35. The bottom portion 35 is formed in a rectangular plate shape. The bottom portion 35 is formed with a fitting groove 35a having a trapezoidal cross section.

The fitted portion 36a of the magnetic pole tooth unit 36 or the fitted portion 37a of the magnetic pole tooth unit 37 is fitted into the fitting groove 35a of the bottom portion 35. Further, in the bottom portion 35, the length of the movable member 2 in the movable direction may be set in accordance with the length of the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 in the movable direction. The fixing of the bottom portion 35 to the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 is performed as follows. The adhesive is applied to one or both of the fitting groove 361a or the fitted portion 371a, and then fitted. Thereby, the bottom portion 33 is fixed to the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37. As a result of the above, the back yoke unit 301 or the back yoke unit 302 is formed. Further, in response to the stroke of the linear motor 1, the number of the back yoke units 301 is selected, and a plurality of back yoke units 301 and one back yoke unit 302 are combined, whereby the back yoke 3 is formed as shown in Fig. 35. . Each of the back yoke unit 301 and the back yoke unit 302 is coupled according to a known method. For example, the back surfaces of the back yoke units 301 and 302 may be fixed by a rectangular plate member.

In the linear motor 1 of the second modification, the magnetic pole tooth units 36 and 37 are formed by laminating a ruthenium steel plate (magnetic pole pieces 361 and 371). The linear motor 1 has a laminated structure in which a part of the thickness direction is formed not only from the magnetic pole teeth 31 but also from the connection portion of the back yoke 3 and the magnetic pole teeth 31. Therefore, the magnetic flux flowing between the adjacent magnetic pole teeth 31 to the connecting portions 361b and 371b is parallel to the surfaces of the magnetic pole pieces 361 and 371. The direction of the eddy current generated by the flow of the magnetic flux is the direction of the plate surface to be penetrated by the magnetic pole pieces 361 and 371. However, the gap between the surfaces of the magnetic pole pieces 361 and 371 or the oxide film formed on the surface thereof is larger in the eddy current direction of the connecting portions 361b and 371b than in the case where the laminated structure is not formed. Therefore, the eddy current flowing to the connecting 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-described effects of the first basic example but also the following effects are obtained. 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 made of a material having a large Young's modulus, such as alumina. Therefore, since the rigidity of the entire back yoke 3 is increased, the warpage caused by the suction force generated between the movable yoke 2 and the movable member 2 can be alleviated. Further, depending on the material of the bottom portion 35, the back yoke 3 can be made thinner when the rigidity exceeds the rigidity required for the entire back yoke 3. Further, in the second modification, the stroke of the linear motor 1 can be changed by changing the number of the back yoke units 301 included in the back yoke 3.

Further, the number of the magnetic pole teeth 31 included in each of the back yoke units 301 and 302 is five, but it is not limited thereto. The bottom portion 33 is provided with the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37, but is not limited thereto. The magnetic pole tooth unit 36 and the magnetic pole tooth unit 37 each have the same number of magnetic pole teeth 31, but are not limited thereto. (Third Modification of Second Embodiment)

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

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

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

In the above-described basic example and the first to third modifications, a gap between the adjacent magnetic pole teeth 31 may be buried by a non-magnetic material such as a resin mold. Thereby, the strength of the back yoke 3 is increased, and the warpage of the yoke 3 after the suction force generated between the movable member 2 and the movable member 2 can be more effectively suppressed.

In the bottom plate 32 of the above-described basic example, a part of the base portion 32 of the magnetic pole tooth 31 and the protruding direction of the magnetic pole tooth 31 (in the thickness direction) may be formed in a laminated structure. In other words, the magnetic pole teeth 31 (the protruding portions 31a and 31a) of the laminated structure may be engaged with the concave portions 32a and 32a in the laminated structure portion of the bottom plate 32 in which a part of the laminated structure is formed. Thereby, as in the first modification and the second modification, the eddy current caused by the magnetic flux flowing in the movable direction of the movable member 2 can be suppressed.

The technical features (constitution elements) described in the respective embodiments can be combined with each other, and by combining, new technical features can be formed. The embodiments disclosed herein are exemplified in all matters and should not be considered as limiting. The scope of the present invention is not intended to be limited by the scope of the invention.

1‧‧‧Linear motor

2‧‧‧ movable

3‧‧‧ Back yoke

4‧‧‧ Armature

21‧‧‧ permanent magnet

22‧‧‧ Holding frame

23‧‧‧ Fixed plate

31‧‧‧Magnetic teeth

32‧‧‧floor

33‧‧‧ bottom

34‧‧‧Magnetic tooth block

35‧‧‧ bottom

36‧‧‧Magnetic tooth unit

37‧‧‧Magnetic tooth unit

41‧‧‧ iron core

42‧‧‧Magnetic teeth

43‧‧‧ drive coil

221‧‧‧ hole

301‧‧‧ Back yoke unit

302‧‧‧ Back yoke unit

311‧‧‧Magnetic pole piece

341‧‧‧Magnetic pole pieces

361‧‧‧Magnetic pole pieces

371‧‧‧Magnetic pole pieces

Fig. 1 is a perspective view showing the configuration of a linear motor according to the 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 movable body of the linear motor of the first embodiment. Fig. 4 is an exploded perspective view showing the configuration of a movable member of the linear motor of the first embodiment. Fig. 5 is a side view showing the flow of the magnetic flux of the linear motor of the first embodiment. Fig. 6 is a view showing the shape of the side surface of the back yoke of the linear motor of the first embodiment. Fig. 7 is a plan view showing an armature material used in the manufacture of the armature of the linear motor of the first embodiment. Fig. 8 is a view showing the winding of the armature of the linear motor of 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 the thrust variation of the electric angle of the linear motor according to the first embodiment. Fig. 11 is a graph showing the thrust characteristics of the linear motor of an example of the first embodiment. Fig. 12 is a graph showing the suction characteristics of the linear motor of an example of the first embodiment. Fig. 13 is a side view showing a configuration of a linear motor of a first conventional example (a configuration in which a magnet array is integrated with a back yoke and configured as a movable member). Fig. 14A is a top view showing the configuration of a 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 a configuration of a linear motor of a second conventional example (a configuration in which only a magnet is arranged as a movable member and a flat rear yoke is used as a stator). Fig. 16A is a top view showing the configuration of a linear motor of the second conventional example. Fig. 16B is a side view showing the configuration of a linear motor of the second conventional example. Fig. 17 is a graph showing the average thrust of the linear motor in the first conventional example, the second conventional example, and the first embodiment. Fig. 18 is a graph showing the average suction force of the linear motor in the first conventional example, the second conventional example, and the first embodiment. Fig. 19 is a graph showing the thrust characteristics of a linear motor of another example of the first embodiment. Fig. 20 is a graph showing the suction characteristics of a linear motor of another example of the first embodiment. Fig. 21 is a graph showing the thrust characteristics of a linear motor of another example of the first embodiment. Fig. 22 is a graph showing the suction characteristics of a linear motor of 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 back yoke. Fig. 26 is a partial perspective view showing a configuration example of a bottom plate included in the back yoke. Figure 27 is a partial perspective view showing the back yoke. Figure 28 is a partial side view showing the linear motor. Figure 29A is a graph showing the Joule loss of a linear motor in accordance with the associated technology. Fig. 29B is a graph showing the Joule loss of the linear motor of the basic example of the second embodiment. Fig. 30 is a side view showing another configuration example of the back yoke. Fig. 31 is a perspective view showing a configuration example of a magnetic pole block. Fig. 32 is a perspective view showing a configuration example of the bottom. 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 according to the first modification of the second embodiment. Fig. 35 is a side view showing another configuration example of the back 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 the magnetic pole tooth unit. Fig. 37 is a perspective view showing a configuration example of the bottom. Fig. 38A is a side view showing another configuration example of the back yoke. Fig. 38B is a perspective view showing a configuration example of the bottom.

Claims (9)

A linear motor comprising: a movable body, a magnet arrangement having a plurality of rectangular permanent magnets; a stator back yoke disposed opposite to the movable body via a gap; and an armature as a stator The movable member is disposed opposite to the back yoke through the gap; the magnetization direction of each of the plurality of permanent magnets is a thickness direction, and the magnetization directions of the adjacent permanent magnets are opposite to each other; the armature is And a plurality of magnetic pole teeth each having a driving coil wound at equal intervals; the back yoke is on a surface facing the movable body, and has a plurality of magnetic poles at a position where the movable direction of the movable member is the same as the magnetic pole teeth of the armature a magnetic pole area of the magnetic pole tooth of the back yoke is 0.9 to 1.1 times the magnetic pole area of the magnetic pole tooth of the armature, a gap between the movable element and the back yoke and a gap between the movable element and the armature Equal or larger. A linear motor according to claim 1, wherein 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. A linear motor according to claim 1 or 2, wherein the length of the movable member is shorter than the length of the armature and shorter than the length of the back yoke. The linear motor of any one of claims 1 to 3, wherein a size of a gap between the movable member and the back yoke and/or a size of a gap between the movable member and the armature is variable. A linear motor comprising: a movable body, a magnet arrangement having a plurality of rectangular permanent magnets; a stator back yoke disposed opposite to the movable body via a gap; and an armature as a stator The movable member is disposed opposite to the back yoke through the gap; the magnetization direction of each of the plurality of permanent magnets is a thickness direction, and the magnetization directions of the adjacent permanent magnets are opposite to each other; the armature is And a plurality of magnetic pole teeth each having a driving coil wound at equal intervals; the back yoke is on a surface facing the movable body, and has a plurality of magnetic poles at a position where the movable direction of the movable member is the same as the magnetic pole teeth of the armature a tooth; the magnetic pole tooth of the back yoke is formed by laminating a plurality of plate-like members in a direction crossing the movable direction of the movable member. The linear motor of claim 5, wherein the back yoke is formed by laminating a plurality of plate-like members in a laminating direction of the magnetic pole teeth from a portion of the magnetic pole teeth that is opposite to a direction in which the magnetic pole teeth protrude. The plate-like member constituting the laminated portion of the back yoke is integrated with the plate-like member constituting the magnetic pole tooth. A linear motor according to claim 5 or 6, wherein the plurality of plate-like members apply an insulating treatment to the laminate. The linear motor of any one of claims 1 to 7, wherein the movable sub-system has a holding member for holding the magnet arrangement, the holding member having a plurality of holes into which the plurality of permanent magnets are inserted. The linear motor of claim 8, wherein the movable sub-system has the holding member and a plate-shaped bottom material for fixing the plurality of permanent magnets.