JP7151698B2 - linear motor - Google Patents

Description

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

Conventionally, for X and Y movement, a method of converting the output of a rotary motor into linear motion using a ball screw has been used. Usage is in progress. A linear motor is generally configured by combining a mover having a plurality of rectangular permanent magnets and an armature having a plurality of magnetic pole teeth.

In addition, since wire bonders and chip mounters in processing machines of semiconductor manufacturing equipment require high-speed repetitive motion, it is preferable to use linear motors that are small in mass and capable of obtaining large acceleration. In order to reduce the size of such a linear motor, for example, as disclosed in Patent Document 1 or 2, the permanent magnet of the mover is not opposed to the entire surface of the armature as the stator, but a movable magnet is used. A linear motor is employed in which the arrangement length of the permanent magnets in the child is shorter than the length of the armature.

A linear motor of this type consists of a mover having a magnet array in which a plurality of permanent magnets are arranged and a flat back yoke integrated with the magnet array, and an armature in which a drive coil is wound around each of a plurality of magnetic pole teeth. are opposed to each other with a gap between them. When the drive coil is energized, the mover (magnet arrangement and back yoke) moves, and the length difference between the mover and the armature becomes the operable stroke of the linear motor.

When the mover is composed of a back yoke made of a ferromagnetic material and a magnet array, an attractive force is generated between the mover and the opposing stator. Due to the generated attraction force, a large vertical force acts on the bearing that supports the mover so that it can move in a predetermined direction. This normal force shortens the bearing life. Also, the direction in which the normal force acts is the direction intersecting with the movable direction of the mover. Therefore, it is necessary to select a bearing in consideration of the normal force. Therefore, a large bearing is selected rather than a bearing suitable for the load of the mover. This leads to an increase in size of the linear motor as a whole.

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

In this type of linear motor, the magnet array and the flat back yoke are separated, and the back yoke faces the magnet array with a gap on the side opposite to the armature, allowing only the magnet array to move. Only the magnet array moves, the back yoke does not move as well as the armature. The length of the magnet array is shorter than the length of the armature, and this length difference is the operable stroke of the linear motor.

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

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

In a linear motor having a mover in which a magnet array and a flat back yoke are integrated (integrated linear motor: patent document 1 or 2, etc.), this attractive force is usually several times to ten times or more the rated thrust. becomes. Therefore, there is a problem that the mover bends due to a large attractive force. As a result, the dimensional accuracy of a processing machine using a linear motor that causes such deflection is deteriorated. In addition, it is necessary to increase the rigidity of the mover, and there is a problem that the configuration becomes large.

Since excessive suction force is also exerted on the linear guide that supports the mover, the linear guide must have a large rated load to withstand this excessive suction force. can't Therefore, it is desirable to reduce the suction force as described above. However, when reducing the attraction force, it is necessary to realize both a compact configuration and a large thrust force generation.

In addition, the integrated linear motor has a problem that the cogging torque becomes large due to the large edge effect, and the detent force becomes large.

In a linear motor (separate type linear motor: Patent Documents 3 to 5, etc.) configured to move only the magnet array by separating the magnet array and the flat back yoke, the magnet array includes the back yoke and the armature. Since the attraction force works from both and, compared with the integrated linear motor, the overall attraction force is smaller. However, in the separated linear motor, the magnetic pole area facing the magnet arrangement is only the area of the facing magnetic pole teeth on the armature side, whereas the area on the back yoke side is almost the same as the area of all the magnets. Therefore, when the magnetic flux density in both gaps is the same, a larger attractive force acts on the back yoke side according to the ratio of the magnetic pole areas, resulting in a significant reduction in the overall attractive force. cannot hope.

Therefore, the magnetic flux density in the gap is reduced by widening the gap between the magnet array and the back yoke, thereby reducing the attractive force between the magnet array and the back yoke to the same extent as the attractive force between the magnet array and the armature. can be considered. However, when the gap between the magnet array and the back yoke is widened, the magnetic flux density for generating thrust from the armature also decreases, resulting in a problem of reduced thrust. Therefore, in the separated linear motors proposed so far, there is a problem that the reduction of the thrust force is inevitable in order to reduce the attraction force acting on the mover.

In the separated linear motor, as described above, the attractive force between the mover (magnet arrangement) and the stator (armature) and the attractive force between the mover and the back yoke are substantially the same. , are reversed, it is possible to reduce the attractive force acting on the mover. However, it has been found that the separation of the back yoke and the magnet arrangement increases the eddy current generated in the back yoke during operation. Increased eddy currents lead to heat generation. Such a linear motor is not suitable for use as a drive source for a stage in an apparatus that must maintain an ambient temperature within a predetermined range, such as a semiconductor manufacturing apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a linear motor capable of significantly reducing the suction force and reducing the detent force while achieving a compact configuration and the generation of a large thrust force. intended to

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

A linear motor according to the present invention includes: a mover having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged; a back yoke as a stator disposed facing the mover with a gap; and an armature as a stator arranged opposite to the back yoke with a gap therebetween. The armature has a plurality of magnetic pole teeth, each of which is wound with a drive coil, at an equal pitch. A plurality of magnetic pole teeth are provided at the same position in the moving direction of the armature as the magnetic pole teeth of the armature. 0.9 times to 1.1 times, and the gap between the mover and the back yoke is equal to or larger than the gap between the mover and the armature.

In the linear motor of the present invention, a mover having a magnet arrangement in which a plurality of permanent magnets are arranged, a back yoke facing the mover with a gap therebetween, and a gap on the side opposite to the back yoke. and an armature arranged to face the mover. The magnet array functions as a mover, and the back yoke and armature function as a stator. Each of the plurality of rectangular permanent magnets in the magnet array is magnetized in the thickness direction, and the magnetization directions are opposite between adjacent permanent magnets. The armature has a plurality of magnetic pole teeth arranged at an equal pitch, and each magnetic pole tooth is wound with a drive coil. The back yoke has a surface facing the mover that is not flat but has a plurality of magnetic pole teeth formed at equal pitches. The pitch of the magnetic pole teeth on the back yoke is equal to the pitch of the magnetic pole teeth on the armature, and the position of the magnetic pole teeth on the back yoke is the same as the magnetic pole teeth on the armature in the moving direction of the mover (linear motor). The magnetic pole area of the magnetic pole teeth of the back yoke is 0.9 to 1.1 times the magnetic pole area of the magnetic pole teeth of the armature. Also, the gap between the mover and the back yoke is greater than the gap between the mover 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 armature. That is, only the back yoke portion to which the driving magnetic flux is applied from the armature is brought close to the mover, and a gap is provided from the mover except for the portion facing the magnetic pole teeth of the armature. Since the magnetic pole area of the armature facing the mover and the magnetic pole area of the back yoke facing the mover are substantially equal, they are effectively canceled out, and the overall attractive force is greatly reduced. Therefore, it is possible to greatly reduce the suction force without increasing the gap between the mover and the back yoke. At this time, since there is no need to increase the gap between the mover and the back yoke, the drop in thrust is small.

In addition, due to the uneven shape of the magnetic pole teeth formed on the back yoke, a sheared region of the drive magnetic flux is generated in the back yoke, so that not only the armature but also the back yoke contributes to the generation of thrust. This thrust generation compensates for the drop in thrust caused by the increased air gaps with the mover at two locations, and a large overall thrust can be obtained. Therefore, it is possible to greatly reduce the attractive force acting on the magnet array (mover) while maintaining a large thrust.

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

If the magnetic pole area of the magnetic pole teeth of the back yoke is too wide, a large amount of magnetic flux is picked up from the surroundings, resulting in a large attractive force. The magnetic flux for the thrust decreases and the thrust decreases. Therefore, the magnetic pole area of the magnetic pole teeth of the back yoke is set to 0.9 to 1.1 times the magnetic pole area of the magnetic pole teeth of the armature.

Since the magnetic pole teeth of the armature are wound with drive coils, the magnetic pole teeth of the armature are not formed very low, and the height of the magnetic pole teeth of the armature is higher than the height of the magnetic pole teeth of the back yoke. For this reason, since the height of the magnetic pole teeth is low in the back yoke, magnetic flux is generated in portions other than the magnetic pole teeth, and the attracting force tends to be larger than that on the armature side. Therefore, the gap between the mover and the back yoke is made equal to or larger than the gap between the mover and the armature so that the attractive force can be effectively canceled.

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

In the linear motor of the present invention, if the height of the magnetic pole teeth of the back yoke is too small compared to the pitch, the effect of providing the magnetic pole teeth (concavo-convex shape) cannot be obtained. If the height of is made too large compared to the pitch, the effect is the same and goes against the trend of miniaturization. Therefore, the height of the magnetic pole teeth in the back yoke is set to 1/20 to 2 times the pitch of the magnetic pole teeth.

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

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

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

In the linear motor of the present invention, the size of the gap between the mover and the back yoke and/or the size of the gap between the mover and the armature are variable. Therefore, by adjusting the size of the gap between the mover and the back yoke and/or the size of the gap between the mover and the armature according to the size of the drive magnetomotive force during use, the attractive force can be reduced to almost zero. It is possible to

A linear motor according to the present invention includes: a mover having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged; a back yoke as a stator disposed facing the mover with a gap; and an armature as a stator arranged opposite to the back yoke with a gap therebetween. The armature has a plurality of magnetic pole teeth, each of which is wound with a drive coil, at an equal pitch. The magnetic pole teeth of the armature and the magnetic pole teeth of the armature are provided at the same positions in the moving direction of the mover, and the magnetic pole teeth of the back yoke form a plurality of plate members in the moving direction of the mover. It is characterized by being laminated in a direction intersecting with.

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

In the linear motor according to the present invention, a part of the back yoke in a direction opposite to the direction in which the magnetic pole teeth protrude from the roots of the magnetic pole teeth is formed by laminating a plurality of plate-like members in the lamination direction of the magnetic pole teeth. The plate member forming the laminated portion of the back yoke and the plate member forming the magnetic pole tooth are integrated.

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

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

In the linear motor of the present invention, the laminated surfaces of the plurality of plate-like members are insulated, so it is possible to further reduce eddy currents.

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

In the linear motor of the present invention, the holding member holds the magnet arrangement (plurality of permanent magnets). Therefore, since the rigidity of the mover (magnet arrangement) is increased, deformation such as bending and bending of the permanent magnet is less likely to occur, and the detent force can be reduced.

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

In the linear motor of the present invention, the magnet arrangement (plurality of permanent magnets) and the holding member are adhesively fixed to the plate-like base material with the plurality of permanent magnets inserted into the holes of the holding member. Therefore, it is possible to further increase the rigidity of the mover (magnet arrangement) to further reduce the detent force, and prevent the permanent magnets from falling off.

In the linear motor of the present invention, it is possible to greatly reduce the attractive force acting on the mover (magnet arrangement) while realizing a compact configuration and generating a large thrust force, and reduce the detent force of the mover. can be done. Therefore, it is possible to suppress deformation due to bending due to a large suction force, and prevent deterioration of the dimensional accuracy of the device using the linear motor. Since the attraction force can be reduced, the rigidity of the movable element and the rigidity of the support system that supports the movable element can be reduced, and not only can the size be reduced, but also the acceleration can be improved by reducing the weight of the movable mass. In addition, by providing the back yoke with a magnetic pole tooth structure, the thrust from the back yoke is applied to the mover, minimizing the decrease in thrust caused by providing a gap between the magnet arrangement and the back yoke. be able to.

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

1 is a perspective view showing the configuration of a linear motor according to Embodiment 1; FIG. 2 is a side view showing the configuration of the linear motor of Embodiment 1; FIG. 4 is a plan view showing the configuration of the mover in the linear motor of Embodiment 1; FIG. 2 is an exploded perspective view showing the configuration of a mover in the linear motor of Embodiment 1; FIG. 4 is a side view showing the flow of magnetic flux in the linear motor of Embodiment 1; FIG. 4 is a diagram showing a side shape of a back yoke in the linear motor of Embodiment 1; FIG. 4 is a plan view showing an armature material used for manufacturing an armature in the linear motor of Embodiment 1; FIG. 4 is a diagram showing armature windings in the linear motor of Embodiment 1. FIG. 2 is a top view showing the configuration of the linear motor of Embodiment 1; FIG. 2 is a side view showing the configuration of the linear motor of Embodiment 1; FIG. 4 is a graph showing a thrust force variation with respect to an electrical angle of the linear motor of the example of Embodiment 1. FIG. 4 is a graph showing thrust characteristics of a linear motor as an example of Embodiment 1; 5 is a graph showing attractive force characteristics of a linear motor as an example of Embodiment 1. FIG. FIG. 2 is a side view showing the configuration of a linear motor of a first conventional example (a configuration in which a magnet arrangement and a back yoke are integrated to form a mover); It is a top view which shows the structure of the linear motor of a 1st prior art example. It is a side view which shows the structure of the linear motor of a 1st prior art example. FIG. 11 is a side view showing a configuration of a linear motor of a second conventional example (a configuration in which only a magnet arrangement is used as a mover and a flat back yoke is used as a stator). FIG. 11 is a top view showing the configuration of a linear motor of a second conventional example; FIG. 11 is a side view showing the configuration of a linear motor of a second conventional example; 7 is a graph showing the average thrust in the linear motors of the first conventional example, the second conventional example, and an example of the first embodiment; 7 is a graph showing the average attraction force in the linear motors of the first conventional example, the second conventional example, and an example of the first embodiment; 7 is a graph showing thrust characteristics of a linear motor of another example of Embodiment 1. FIG. 7 is a graph showing attractive force characteristics of another linear motor according to the first embodiment; 7 is a graph showing thrust characteristics of a linear motor of still another example of Embodiment 1; 9 is a graph showing attraction force characteristics of a linear motor of still another example of Embodiment 1; FIG. 11 is a perspective view showing a configuration example of a linear motor according to Embodiment 2; FIG. 8 is a side view showing a configuration example of a linear motor according to Embodiment 2; 4 is a perspective view showing a configuration example of magnetic pole teeth included in the back yoke; FIG. FIG. 4 is a partial perspective view showing a configuration example of a base plate included in the back yoke; FIG. 4 is a partial perspective view of a back yoke; It is a partial side view of a linear motor. It is a graph which shows the joule loss of the linear motor by related technology. 9 is a graph showing Joule loss of a linear motor in a basic example of Embodiment 2; FIG. 11 is a side view showing another configuration example of the back yoke; It is a perspective view which shows the structural example of a magnetic pole tooth block. It is a perspective view which shows the structural example of a base part. It is a partial side view of a linear motor. 9 is a graph showing Joule loss of a linear motor in a basic example of Embodiment 2; 9 is a graph showing Joule loss of a linear motor in the first modified example of the second embodiment; FIG. 11 is a side view showing another configuration example of the back yoke; FIG. 4 is a perspective view showing a configuration example of a magnetic pole tooth unit; FIG. 4 is a perspective view showing a configuration example of a magnetic pole tooth unit; It is a perspective view which shows the structural example of a base part. FIG. 11 is a side view showing another configuration example of the back yoke; It is a perspective view which shows the structural example of a base part.

Hereinafter, the present invention will be described in detail based on the drawings showing its embodiments.

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

A linear motor 1 includes a mover 2 , a back yoke 3 and an armature 4 . A back yoke 3 is opposed to the mover 2 with a gap therebetween, and an armature 4 is opposed to the back yoke 3 with a gap in the mover 2. - 特許庁The back yoke 3 and armature 4 function as a stator.

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

As shown in FIG. 4, the holding frame 22 has a rectangular plate shape. The thickness of the holding frame 22 is smaller than the thickness of the permanent magnet 21 . 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 has a shape corresponding to that of the permanent magnet 21 . Each permanent magnet 21 is fitted in a hole 221 and fixed to the holding frame 22 with an adhesive. The holes 221 are provided so that the permanent magnets 21 fixed to the holding frame 22 are arranged side by side at equal pitches. When fixing the permanent magnets 21 to the holding frame 22, they are fitted into the holes 221 so that the magnetization directions of the adjacent permanent magnets 21, 21 are opposite to each other. As shown in FIG. 3, each permanent magnet 21 is skewed at an angle θ.

The holding frame 22 is fixed to the fixed plate 23 with an adhesive in a state in which the plurality of permanent magnets 21 are inserted into the holes 221 of the holding frame 22 and held. The bottom surface of each permanent magnet 21 is also adhered to the fixed plate 23 . The fixing plate 23 is made of non-magnetic SUS or the like. Since the magnet arrangement is held by the holding frame 22 and adhered to the fixing plate 23, the rigidity of the mover 2 is high and the permanent magnets 21 do not come off. The mover 2 is arranged in the gap between the back yoke 3 and the armature 4 so that the fixed plate 23 faces the back yoke 3 . Note that the fixing plate 23 is not essential, and is unnecessary when the permanent magnet 21 is sufficiently held by the holding frame 22 .

The lengths of the back yoke 3 and the armature 4 in the movable direction (horizontal direction in FIG. 2) are substantially equal, and the lengths of the movable element 2 in the movable direction (horizontal direction in FIG. 2) are equal to those of the back yoke 3 and the armature 4, and the length difference is the operable stroke of the linear motor 1. With such a configuration, an attempt is made to reduce the edge effect.

The surface of the back yoke 3, which is made of soft steel, preferably a soft magnetic material (for example, a silicon steel plate), on the side not facing the mover 2 is flat, but the surface of the back yoke 3 on the side facing the mover 2 is flat. A plurality of rectangular magnetic pole teeth 31 are formed at equal pitches in the moving direction instead of being flat. The height of each magnetic pole tooth 31 is 1/20 to 2 times the formation pitch of the magnetic pole teeth 31, preferably 1/10 to 1 time. For example, the height of each magnetic pole tooth 31 is about half the formation pitch of the magnetic pole teeth 31 .

In the armature 4, a plurality of rectangular magnetic pole teeth 42 made of a soft magnetic material are integrally provided on a core 41 made of a soft magnetic material at equal pitches in the moving direction. 43 is wound.

The pitch of the magnetic pole teeth 31 in the back yoke 3 is equal to the pitch of the magnetic pole teeth 42 of the armature 4, and the position of each magnetic pole tooth 31 in the back yoke 3 is equal to that of each magnetic pole tooth 42 of the armature 4 in the moving direction of the mover 2. is the same as the position of The shape of the magnetic pole surface of the magnetic pole tooth 31 of the back yoke 3 facing the mover 2 is substantially the same as that of the magnetic pole surface of the magnetic pole tooth 42 of the armature 4 facing the mover 2, and is rectangular. The magnetic pole area of the former is 0.9 to 1.1 times the magnetic pole area of the latter. For example, the magnetic pole face of the magnetic pole tooth 31 and the magnetic pole face of the magnetic pole tooth 42 have the same rectangular shape and the same area. Also, the gap between the mover 2 and the back yoke 3 is the same as or larger than the gap between the mover 2 and the armature 4 . For example, the latter gap is 0.5 mm and the former gap is 0.5 mm or more. In this case, the gap between the mover 2 and the back yoke 3 does not include the thickness of the fixed plate 23 even if the fixed plate 23 is included in the configuration, and the gap between the mover 2 itself and the back yoke 3 (shortest distance) distance). In other words, this gap is a magnetic gap (magnetic gap), and there is no need to consider the thickness of the fixed plate 23, which is a non-magnetic material.

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

In the linear motor 1 of Embodiment 1, the surface of the back yoke 3 facing the mover 2 has magnetic pole surfaces of substantially the same shape at the same positions as the magnetic pole teeth 42 of the armature 4 in the moving direction. Magnetic pole teeth 31 having substantially the same magnetic pole area are formed. Therefore, the magnitude of the attraction force generated between the mover 2 and the back yoke 3 is substantially equal to the magnitude of the attraction force generated between the mover 2 and the armature 4. are effectively canceled out, the attractive force acting on the mover 2 as a whole of the linear motor 1 becomes very small. As described above, in the linear motor 1 of Embodiment 1, the attractive force can be significantly reduced without increasing the gap between the mover 2 and the back yoke 3 . Therefore, since it is not necessary to increase the gap between the mover 2 and the back yoke 3, the thrust does not decrease.

Further, in the linear motor 1 of Embodiment 1, as described above, the armature 4 having the plurality of magnetic pole teeth 42 at equal pitches, and the plurality of magnetic pole teeth 42 of the armature 4 at the same positions in the moving direction as the magnetic pole teeth 42 of the armature 4 . Since the mover 2 is arranged between the back yoke 3 having the magnetic pole teeth 31, the cogging torque of the magnet arrangement in the direction perpendicular to the moving direction is reduced. reduction can be achieved. Furthermore, since the magnet arrangement is held by the holding frame 22 and fixed to the fixed plate 23 by adhesion, the rigidity of the mover 2 can be increased, so that the permanent magnets 21 are less likely to deform such as flexing and bending. However, it contributes to the reduction of the detent force of the mover 2 .

In the linear motor 1 of Embodiment 1, a plurality of magnetic pole teeth 31 are formed on the back yoke 3, and the uneven shape facing the mover 2 generates a shearing region of the driving magnetic flux. In addition, the back yoke 3 also contributes to the generation of thrust. FIG. 5 is a side view showing the flow of magnetic flux in the linear motor 1 of Embodiment 1. FIG. In FIG. 5, arrows indicate the flow of magnetic flux. In the linear motor 1, thrust is generated by shearing magnetic flux on the armature 4 side, and thrust is also generated by shearing magnetic flux on the back yoke 3 side. is the sum of In a linear motor having a flat back yoke without forming the magnetic pole teeth 31 as in Embodiment 1, no thrust is generated on the back yoke side, and only thrust due to shearing of magnetic flux on the armature side is generated. becomes.

In the linear motor 1 of Embodiment 1, since a gap is also provided between the mover 2 and the back yoke 3, there is concern that this gap may reduce the thrust force. However, as described above, since thrust can be generated on the back yoke 3 side as well, it is possible to compensate for the drop in thrust due to the gap and achieve a large thrust.

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

In addition, in the linear motor 1 of Embodiment 1, since the attractive force can be reduced, even if the permanent magnet 21 and the holding frame 22 with low rigidity are used, no problem occurs. Therefore, it is possible to reduce the size of the mover 2 and realize a large acceleration due to the weight reduction of the mover 2 . Further, since the wear of the mover 2 is small, the life of the linear motor 1 can be extended.

In a linear motor, in order to move the mover smoothly, it is common to provide a linear guide on the side surface of the mover as will be described later. Therefore, a linear guide with low rigidity can be used, which also contributes to miniaturization and extension of the life of the linear motor.

In the linear motor 1 of Embodiment 1, the length of the mover 2 is made shorter than the lengths of the back yoke 3 and the armature 4 to further reduce the size, weight, and speed of the motor.

A specific configuration of the linear motor 1 according to Embodiment 1 manufactured by the present inventor and characteristics of the manufactured linear motor 1 will be described below.

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

In addition, unlike the above example, the holding frame 22 may be manufactured by stacking six sheets of 0.5 mm thick SUS plates with holes formed by press working and fixing them by caulking. good. In this case, the manufacturing cost can be reduced.

Next, a back yoke 3 was produced. FIG. 6 is a diagram showing a side shape of the back yoke 3 in the linear motor 1 of Embodiment 1. FIG.

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

Next, an armature 4 was produced. FIG. 7 is a plan view showing an armature material used for manufacturing the armature 4 in the linear motor 1 of Embodiment 1. FIG. 164 pieces of the armature material 44 having a shape as shown in _FIG . A block body (width: 82 mm, height: 31 mm, length: 263.04 mm) (core 41 with 18 magnetic pole teeth 42 of the same shape (width: 6 mm, height: 25 mm, length: 82 mm, magnetic pole A structure having an area of 492 mm ² ) at an equal pitch (15.12 mm) was obtained.

Next, winding wires were inserted into this block. FIG. 8 is a diagram showing windings of the armature 4 in the linear motor 1 of Embodiment 1. FIG. A drive coil 43 is formed by winding 17 turns of an enamel-coated conductor wire with a diameter of 2 mm around the arm portion of each magnetic pole tooth 42 of the armature 4 and fixing it by impregnating it with varnish.

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

Next, the back yoke 3 and the armature 4 thus produced were fixed using a jig so that the distance therebetween was maintained at a constant 6 mm. The gap between the back yoke 3 and the armature 4 was fixed to be 6 mm, but the structure was such that this gap could be adjusted after the linear motor 1 was assembled. Next, after attaching a linear guide (not shown) to the side surface of the mover 2, a 5 mm thick guide was inserted between the back yoke 3 and the armature 4 at a predetermined distance from each of the back yoke 3 and the armature 4. A linear motor 1 was produced by inserting the mover 2 of . At this time, the gap distance between the mover 2 and the magnetic pole teeth 31 of the back yoke 3 and the gap distance between the mover 2 and the magnetic pole teeth 42 of the armature 4 were both 0.5 mm. A load cell was provided between the linear guide and the armature 4 so as to measure the attractive force.

Since the gap between the back yoke 3 and the armature 4 can be adjusted, the gap between the mover 2 and the armature 4 (magnetic pole teeth 42) can be adjusted while the gap between the mover 2 and the armature 4 (magnetic pole teeth 42) is kept constant. The distance of the gap from the magnetic pole tooth 31) can be arbitrarily set and made variable. By adjusting the insertion position of the mover 2 into the gap between the back yoke 3 and the armature 4, the distance between the mover 2 and the back yoke 3 (magnetic pole teeth 31) and the gap between the mover 2 and the armature 4 can be changed. It is also possible to set the ratio of the gap distance to the child 4 (magnetic pole tooth 42) to a desired value.

In addition, as a mechanism for adjusting the gap between the linear guide that supports the armature 4 and the mover 2 and between the armature 4 and the back yoke 3, a mechanism for adjusting the height by inserting a gap adjusting screw and a cross-sectional shape A mechanism for adjusting the height by inserting a tapered shim plate with a screw can be adopted.

9A and 9B are diagrams showing the configuration of an example of the linear motor 1 according to Embodiment 1 manufactured in this manner, FIG. 9A being a top view thereof and FIG. 9B being a side view thereof. In FIG. 9B , the hollow arrow indicates the magnetization direction of the permanent magnet 21 and the solid arrow indicates the movable direction of the mover 2 . Further, details of manufacturing specifications of the linear motor 1 are as follows.

Magnetic pole configuration: 7 poles 6 slots Material of permanent magnet 21: Nd-Fe-B rare earth magnet (Hitachi Metals NMX
-S49CH material)
Shape of permanent magnet 21: thickness 5.0 mm, width 12 mm, length 82 mm
Pitch of permanent magnet 21: 12.96 mm
Skew angle of permanent magnet 21: 3.2°
Shape of back yoke 3: thickness 6.0 mm, width 90 mm, length 263.04 mm
Material of back yoke 3: Mild steel (JIS standard G3101 type symbol SS400 material)
Shape of magnetic pole tooth 31: width 6.0 mm, height: 3.0 mm, length: 82 mm
Pitch of magnetic pole teeth 31: 15.12 mm
Body size of core 41: height 31 mm, width 82 mm, length 263.04 mm
Material of core 41: Silicon steel plate (JIS standard C2552 type symbol 50A800 material)
Shape of magnetic pole tooth 42: width 6.0 mm, height: 25 mm, length: 82 mm
Pitch of magnetic pole teeth 42: 15.12 mm
Shape of drive coil 43: width 15.12 mm, height 23 mm, length 91.12 mm
Winding thickness of drive coil 43: 4.06 mm
Diameter and number of windings of drive coil 43: 2 mm in diameter, 17 turns Winding resistance (one piece): 0.0189 Ω
Mass of mover 2: 516.6 g

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

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

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

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

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

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

By the way, in order to evaluate the linear motor 1 of Embodiment 1 in comparison with a conventional linear motor, two types of linear motors (a first conventional example and a second conventional example) were produced as conventional examples, and their Characteristics (thrust and suction) were measured.

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

A linear motor 50 of the first conventional example has a mover 51 formed by integrating a magnet array 52 and a back yoke 53, and an armature 54 facing the mover 51 with a gap. In the first conventional example, the structure in which the magnet array 52 and the back yoke 53 are integrated functions as a mover, and the armature 54 functions as a stator.

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

14A and 14B are diagrams showing the configuration of such a first conventional linear motor 50, FIG. 14A being a top view and FIG. 14B being a side view. In FIG. 14B , the hollow arrow indicates the magnetization direction of the permanent magnet 55 and the solid arrow indicates the movable direction of the mover 51 . The size of the gap between the mover 51 and the armature 54 was 0.5 mm or 1 mm. Details of manufacturing specifications of the linear motor 50 are as follows.

Magnetic pole configuration: 7 poles 6 slots Material of permanent magnet 55: Nd-Fe-B rare earth magnet (Hitachi Metals NMX
-S49CH material)
Shape of permanent magnet 55: thickness 5.0 mm, width 12 mm, length 82 mm
Pitch of permanent magnets 55: 12.96 mm
Skew angle of permanent magnet 55: 3.2°
Shape of back yoke 53: thickness 6.0 mm, width 90 mm, length 190 mm
Material of back yoke 53: Mild steel (JIS standard G3101 type symbol SS400 material)
Body size of core 56: height 31 mm, width 82 mm, length 263.04 mm
Material of core 56: Silicon steel plate (JIS standard C2552 type symbol 50A800 material)
Shape of magnetic pole tooth 57: width 6.0 mm, height: 25 mm, length: 82 mm
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 and number of windings of the drive coil 58: diameter 2 mm, 17 turns Winding resistance (one piece): 0.0189 Ω
Mass of mover 51 (magnet array 52 + back yoke 53): 1321.01 g

The length in the movable direction (horizontal direction in FIG. 13) of the mover 51 (integrated configuration of the magnet array 52 and the back yoke 53) is shorter than the length of the armature 54. It becomes an operable stroke.

Next, the configuration of the second conventional example will be described. FIG. 15 is a side view showing the configuration of the linear motor of the second conventional example. The second conventional example is a linear motor (separate type linear motor) having a configuration conforming to Patent Documents 3-6. In FIG. 15, only the magnet array 62 is shown in cross section from a direction parallel to the moving direction so that the arrangement of the magnets can be seen.

The linear motor 60 of the second conventional example has a magnet arrangement 62, a back yoke 63 arranged to face the magnet arrangement 62 with a gap, and a gap arranged to face the magnet arrangement 62 on the opposite side of the back yoke 63. and an armature 64 . Only the magnet array 62 functions as a mover, and the back yoke 63 and armature 64 function as stators.

The configuration of the magnet array 62 is the same as the configuration of the magnet array of the mover 2 described above. That is, the magnet array 62 is configured by holding and fixing a plurality of rectangular permanent magnets 65 in a holding frame made of a non-magnetic material at equal pitches and installing them in the movable direction (horizontal direction in FIG. 15). 65 is magnetized in the thickness direction (vertical direction in FIG. 15), and the magnetization directions of adjacent permanent magnets 65, 65 are opposite to each other. The back yoke 63 made of mild steel has a flat plate-like surface not only on the side not facing the magnet array 62 but also on the side facing the magnet array 62 . does not exist. The configuration of the armature 64 is the same as the configuration of the armature 4 described above, and a plurality of magnetic pole teeth 67 are integrally provided on the core 66 at equal pitches in the moving direction. A drive coil 68 is wound on the .

16A and 16B are diagrams showing the configuration of such a linear motor 60 of the second conventional example, FIG. 16A being its top view and FIG. 16B being its side view. In FIG. 16B, hollow arrows represent the magnetization direction of the permanent magnet 65, and solid line arrows represent the movable direction of the magnet array 62 (mover). The size of the gap between the magnet array 62 and the back yoke 63 and the size of the gap between the magnet array 62 and the armature 64 were both 0.5 mm. Further, details of manufacturing specifications of the linear motor 60 are as follows.

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

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

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

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

In FIGS. 17 and 18, A denotes a linear motor 50 (hereinafter referred to as linear motor 50) in the first conventional example of integrated magnet arrangement 52 and back yoke 53 with a gap of 0.5 mm between the mover 51 and the armature 54. and B is a linear motor 50 (hereinafter referred to as a linear motor 50B), and C is the gap between the magnet array 62 and the back yoke 63 and the gap between the magnet array 62 and the armature 64 in the second conventional example in which the magnet array 62 and the back yoke 63 are separated from each other. The linear motor 60 has a gap of 0.5 mm for both. The linear motor 1 has a gap between the back yoke 3 and a gap between the mover 2 and the armature 4, both of which are set to 0.5 mm.

In the linear motor 50A (A in the figure) of the first conventional example, the maximum thrust is 1030N, but the attractive force is 4200N, which is about four times as large as the thrust. In the linear motor 50B (B in the figure) as a countermeasure for reducing the attraction force, the obtained thrust is remarkably lowered to 909N, whereas the attraction force is 3360N without much reduction. Therefore, it is understood that sufficient countermeasures are not taken.

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

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

By the way, in the linear motor 1 of the example of Embodiment 1, as shown in FIG. 12, the magnitude of the attractive force changes depending on the magnitude of the drive magnetomotive force. Therefore, by adjusting the size of the gap between the mover 2 and the back yoke 3 according to the thrust force region (driving magnetomotive force) that is often used, the attractive force can be further reduced.

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

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

In another example, when the driving magnetomotive force is 1200A, the thrust is 978N, which is slightly lower than the previous example. has been realized. This is a level of attractive force at which the linear guide, mover, and surrounding structures can be disregarded for deformation and life reduction due to the attractive force. Therefore, when used with a drive magnetomotive force of around 1200 A, it can be seen that the linear motor 1 of another example is more suitable for the purpose of reducing the attractive force than the example described above.

Further, as still another example of the first embodiment, the linear motor 1 is configured such that the gap between the mover 2 and the armature 4 is kept at 0.5 mm and the gap between the mover 2 and the back yoke 3 is set at 0.66 mm. was made. Other configurations are the same as the example described above.

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

In yet another example, when the driving magnetomotive force is 1200A, the thrust is 984N, which is slightly lower than the previous example. We have achieved zero. Therefore, when used with a driving magnetomotive force of around 600 A, it can be seen that the linear motor 1 of still another example is optimal for reducing the attractive force.

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

In the embodiment described above, an example in which the size of the gap between the mover 2 and the armature 4 is fixed and the size of the gap between the mover 2 and the back yoke 3 is varied has been described. Second, the size of the gap between the mover 2 and the back yoke 3 is fixed, and the size of the gap between the mover 2 and the armature 4 is changed. is fixed and the position of the mover 2 is changed, it is possible to realize an attractive force close to zero.

Further, in the above embodiment, the linear motor 1 having the configuration in which the mover 2 is shorter than the armature 4 has been described. (forming magnetic pole teeth on the back yoke) can be applied.

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

A linear motor 1 of Embodiment 2 includes a mover 2, a back yoke 3, and an armature 4, as in Embodiment 1, and the back yoke 3 and armature 4 function as a stator.

The configuration of the mover 2 and the armature 4 in the linear motor 1 of Embodiment 2 is the same as the configuration of the mover 2 and the armature 4 in the linear motor 1 of Embodiment 1 described above. are omitted.

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

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

As shown in FIG. 24, the back yoke 3 and the armature 4 have approximately the same length in the movable direction (horizontal direction in FIG. 24). Also, the pitch of the magnetic pole teeth 31 in the back yoke 3 is equal to the pitch of the magnetic pole teeth 42 in the armature 4 . The position of each magnetic pole tooth 31 in the back yoke 3 is the same as the position of each magnetic pole tooth 42 of the armature 4 in the movable direction of the mover 2 . The magnetic pole face of the magnetic pole tooth 31 and the magnetic pole face of the magnetic pole tooth 42 have the same rectangular shape and the same area. Also, the gap between the mover 2 and the back yoke 3 is substantially the same as the gap between the mover 2 and the armature 4 .

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

During operation of the linear motor 1 , an attractive force is generated between the magnetic pole teeth 31 of the back yoke 3 and the permanent magnets 21 of the mover 2 . An attractive force is also generated between the magnetic pole teeth 42 of the armature 4 and the permanent magnets 21 of the mover 2 . The two attractive forces acting on the mover 2 are in opposite directions. By adjusting the magnetic circuit such that 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 the same area, the magnitudes of the attractive forces can be made substantially equal. Thereby, the attractive force generated between the magnetic pole tooth 31 and the permanent magnet 21 and the attractive force generated between the magnetic pole tooth 42 and the permanent magnet 21 can be balanced. That is, the two attractive forces can cancel each other. If it is difficult to balance the two attractive forces due to factors such as machining errors and assembly errors, the spacing between the magnetic pole teeth 31 and the permanent magnets 21 or the spacing between the magnetic pole teeth 42 and the permanent magnets 21 should be adjusted. to balance the two forces of attraction.

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

The configuration of the back yoke 3, which is a feature of the second embodiment, will be described in detail below. 25 is a perspective view showing a configuration example of the magnetic pole teeth 31 included in the back yoke 3. FIG. The magnetic pole tooth 31 has a T-shaped cross section and has two projecting portions 31a, 31a projecting in the short direction from the bottom portion (lower side in FIG. 25). Protrusions 31a, 31a (for this reason, in FIG. 25, the H shape is turned sideways) are portions that engage with recesses 32a, 32a of a dovetail groove 321, which will be described later. During operation of the linear motor 1 , the lateral direction of the magnetic pole teeth 31 is parallel to the moving direction of the mover 2 .

The magnetic pole tooth 31 is formed by stacking magnetic pole pieces 311 . The magnetic pole piece 311 includes an engaging projection 311a formed by cutting out a portion of a rectangular plate. The magnetic pole piece 311 is formed of a thin plate of soft magnetic silicon steel or the like. The laminated magnetic pole pieces 311 are fixed to each other by heat welding, caulking, or the like. In the case of heat welding, for example, first, the surfaces of the magnetic pole pieces 311 are coated with a thermosetting adhesive or coated with a heat-welding coating. . The heating fixes the pole pieces 311 together.

Eddy current loss is reduced as the thickness of the magnetic pole piece 311 forming the magnetic pole tooth 31 is reduced, that is, as the number of magnetic pole pieces 311 is increased. Considering the strength and labor required for assembly, the thickness of the pole piece 311 is desirably about 0.2 to 0.5 mm. The number and plate thickness of the magnetic pole piece 311 constituting the magnetic pole tooth 31 may be appropriately designed according to required specifications.

FIG. 26 is a partial perspective view showing a configuration example of the base plate 32 included in the back yoke 3. FIG. For convenience of explanation, FIG. 26 is drawn upside down from FIGS. 24 and 25 . A dovetail groove 321 is provided in the base plate 32 along the lateral direction. The dovetail groove 321 has a shape corresponding to the projecting portion 311a of the magnetic pole piece 311 (the projecting portion 31a of the magnetic pole tooth 31). The dovetail groove 321 has a concave portion 32a corresponding to the projecting portion 311a (projecting portion 31a). As shown in FIGS. 24 and 25, the base plate 32 has a plurality of dovetail grooves 321 formed therein. A plurality of dovetail grooves 321 are provided at equal pitches along the moving direction of the mover 2 . The array direction of the plurality of dovetail grooves 321 is parallel to the moving direction of the mover 2 when the linear motor 1 operates.

FIG. 27 is a partial perspective view of the back yoke 3. FIG. As in FIG. 26, the vertical direction is reversed from that of FIGS. 24 and 25 for convenience of explanation. In the back yoke 3 , the projecting portion 31 a of the magnetic pole tooth 31 is engaged with the dovetail groove 321 .

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

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

Next, reduction of eddy current will be described. FIG. 28 is a partial side view of the linear motor 1. FIG. In FIG. 28, an example of a magnetic flux flow is indicated by a solid arrow, and an example of an eddy current is indicated by a dotted arrow. As shown in FIG. 28, in the magnetic pole tooth 31, the magnetic flux flows in the vertical direction of the drawing. That is, it flows in a direction parallel to the plate surface of the magnetic pole piece 311 that constitutes the magnetic pole tooth 31 . The eddy current tends to flow in a direction that hinders the change of magnetic flux on a plane perpendicular to the direction in which the magnetic flux flows. That is, in the case shown in FIG. 28, the magnetic flux tends to flow in the counterclockwise direction perpendicular to the direction in which the magnetic flux flows. The direction of this eddy current is the direction of penetrating the plate surface of the magnetic pole piece 311 forming the magnetic pole tooth 31 . However, since the magnetic pole tooth 31 has a plurality of laminated magnetic pole pieces 311 and the electric resistance between the magnetic pole pieces 311 is large, it is possible to reduce the eddy current. Furthermore, when the plate surface (surface) of the magnetic pole pieces 311 is coated with an insulating film, it is possible to further reduce the eddy current flowing between the magnetic pole pieces 311 .

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

The horizontal axis in FIGS. 29A and 29B is the electrical angle indicating the position of the mover 2. In FIG. The unit of the horizontal axis is degrees (°). The vertical axis in FIGS. 29A and 29B is Joule loss due to eddy currents. The unit is watt (W). The graph labeled with back yoke shows the joule loss in the back yoke. As shown in FIG. 29A, in the linear motor according to the related technology in which the magnetic pole teeth are not laminated, the joule loss in the back yoke is about 80 W. In the linear motor 1, the Joule loss in the back yoke 3 is reduced to around 50W.

In FIGS. 29A and 29B, the graphs labeled U, V, and W show absolute values of Joule loss due to energization occurring in the U-phase, V-phase, and W-phase coils, respectively. Note that in FIGS. 29A and 29B, the joule loss in the coil due to the energization of the coil is the same, but there is a large difference in the joule loss in the back yoke. This result is an example showing that Joule loss due to eddy current can be reduced when the magnetic pole tooth is of a laminated structure compared to when the magnetic pole tooth is not of a laminated structure under the same size and shape. Although the absolute value of the Joule loss due to the eddy current changes depending on the velocity, the ratio of both effects is maintained at the same speed.

The linear motor 1 according to Embodiment 2 has the following effects. The magnetic pole teeth 31 are constructed by stacking magnetic pole pieces 311 formed of silicon steel plates. Therefore, the direction of the eddy current is the direction of penetrating the plate surface. At this time, the electrical resistance of the magnetic pole tooth 31 in the eddy current direction is reduced by the gap on the surface of the magnetic pole piece 311, the contact resistance between the magnetic pole pieces, the oxide film formed on the surface of the magnetic pole piece 311, and the like. It is larger than the case of forming with Therefore, it is possible to reduce the eddy current flowing through the magnetic pole tooth 31 . The surface (laminated surface) of the pole piece 311 may be subjected to an insulating treatment such as forming a film of an insulating material. When the insulation treatment is applied, it becomes possible to further reduce the eddy current between the silicon steel plates.

Further, in Embodiment 2, the magnetic pole teeth 31 of the back yoke 3 have a laminated structure. For example, if the entire back yoke is made of laminated steel plates, there is a concern that the rigidity will decrease. In that case, there is a risk that the back yoke 3 will bend due to the attraction force generated between it and the mover 2 . However, in the basic example, only the magnetic pole tooth 31 has a laminated structure, and the base plate 32 to which the magnetic pole tooth 31 is fixed does not have a laminated structure. Therefore, the bending of the back yoke 3 is caused by the related technology (when the magnetic pole teeth 31 and the base plate 32 are respectively formed of a soft magnetic material, or when the magnetic pole teeth 31 and the base plate 32 are integrally formed of a soft magnetic material). It is minor in comparison.

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

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

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

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

Next, reduction of eddy current will be described. 33 is a partial side view of the linear motor 1. FIG. In FIG. 33, an example of magnetic flux flow is indicated by a solid arrow, and an example of eddy current is indicated by a dotted arrow. The reduction of the eddy current in the magnetic pole tooth 31 is the same as in the basic example described above, so the explanation is omitted. Here, reduction of eddy currents at the connecting portion 341b of the magnetic pole tooth block 34 will be described. As shown in FIG. 33, the magnetic flux flows in the left-right direction of the drawing at the connecting portion 341b. That is, it flows in a direction parallel to the plate surface of the magnetic pole tooth piece 341 that constitutes the magnetic pole tooth block 34 . The eddy current tends to flow in a direction that hinders the change of magnetic flux on a plane perpendicular to the direction in which the magnetic flux flows. In other words, as shown in FIG. 33, the magnetic flux tends to flow counterclockwise around the direction in which the magnetic flux flows. The direction of this eddy current is the direction of penetrating the plate surface of the magnetic pole tooth piece 341 constituting the magnetic pole tooth block 34 . However, since the magnetic pole tooth block 34 has a plurality of laminated magnetic pole teeth 341 and the electric resistance between the magnetic pole teeth 341 is large, it is possible to reduce the eddy current. Furthermore, when the plate surface is coated with an insulating film, the eddy current flowing between the magnetic pole teeth 341 can be further reduced.

Furthermore, the height of the connecting portion 341b will be described. As shown in FIG. 33, the height of the connecting portion 341b is d. The magnetic flux flowing between adjacent magnetic pole teeth 31 flows in the horizontal direction of the drawing. The path along which the magnetic flux flows follows the shortest path. Therefore, the magnetic flux does not flow in the portion separated from the magnetic pole tooth 31 by a certain distance or more. Therefore, the height d of the connecting portion 341b should be set to a value that allows the magnetic flux in the horizontal direction of the paper to flow sufficiently. Also, the base portion 33 through which magnetic flux does not flow can be made of a non-magnetic material. For example, the base portion 33 is made of alumina having high rigidity and a large Young's modulus. Alternatively, nonmagnetic stainless steel, aluminum alloy, or the like can be used.

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

As shown in FIG. 34A, in the linear motor 1 of the basic example, the Joule loss of the back yoke 3 is around 50 W, whereas in the linear motor 1 of the first modified example, as shown in FIG. 3 is reduced to around 2.5W. This is because, since the connection portion 341b has a laminated structure, the eddy current due to the magnetic flux flowing through the connection portion 341b is also reduced. In FIGS. 34A and 34B, the graphs labeled U, V, and W show absolute values of Joule loss due to energization occurring in the U-phase, V-phase, and W-phase coils, respectively. Note that in FIGS. 34A and 34B, the joule loss in the coil due to the energization of the coil is the same, but there is a large difference in the joule loss in the back yoke. This result shows that the Joule loss due to eddy current can be reduced in the case where only the magnetic pole teeth have a laminated structure and in the case where the magnetic pole teeth and part of the back yoke have a laminated structure under the same size and shape. This is an example, and although the absolute value of Joule loss due to eddy current changes depending on the size of the linear motor and the speed of the linear motor, the ratio of both effects is maintained at the same speed.

In the linear motor 1 according to the first modification, the magnetic pole tooth block 34 is constructed by stacking silicon steel plates (magnetic pole tooth pieces 341). In the linear motor 1 , in addition to the magnetic pole teeth 31 , a portion of the back yoke 3 connected to the magnetic pole teeth 31 in the thickness direction has a laminated structure. Therefore, the magnetic flux flowing through the connecting portion 341 b between the adjacent magnetic pole teeth 31 is parallel to the surface of the magnetic pole tooth piece 341 . The direction of the eddy current generated by the flow of magnetic flux is the direction of penetrating the plate surface of the magnetic pole tooth piece 341 . However, due to the gaps on the surface of the magnetic pole tooth piece 341 and the oxide film formed on the surface thereof, the electrical resistance in the eddy current direction at the connecting portion 341b is greater than in the case where the laminated structure is not used. Therefore, it is possible to reduce the eddy current flowing through the connecting portion 341b. Therefore, the eddy current flowing through the back yoke 3 can be further reduced.

Moreover, in the first modified example, in addition to the above-described effects of the basic example 1, the following effects are obtained. Since the base portion 33, which is a part of the back yoke 3, can be made of a non-magnetic material, it can be made of a material with a high Young's modulus, such as alumina. As a result, the rigidity of the back yoke 3 as a whole is increased, so that bending caused by the attraction force generated between the back yoke 3 and the mover 2 can be reduced. Furthermore, when the rigidity of the back yoke 3 as a whole exceeds the required rigidity due to the material of the base portion 33, the thickness of the back yoke 3 can be reduced.

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

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

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

The magnetic pole tooth unit 37 is formed by laminating a plurality of magnetic pole tooth pieces 371 . The stacking direction of the magnetic pole tooth pieces 371 is a direction that intersects the arrangement direction of the magnetic pole teeth 31 . The magnetic pole tooth piece 371 has substantially the same configuration as the magnetic pole tooth piece 361 . In the following, the differences between the magnetic pole tooth piece 371 and the magnetic pole tooth piece 361 will be mainly described. The magnetic pole tooth piece 371 includes a mated portion 371a, a connecting portion 371b, and a plurality of protrusions 371c. A connecting portion 361b of the magnetic pole tooth piece 361 protrudes in the longitudinal direction at one end in the longitudinal direction. On the other hand, the connecting portion 371b of the magnetic pole tooth piece 371 does not protrude in the longitudinal direction at both ends in the longitudinal direction. The rest of the configuration of the magnetic pole tooth piece 371 is the same as that of the magnetic pole tooth piece 361, so the description is omitted.

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

A fitted portion 36 a of the magnetic pole tooth unit 36 or a fitted portion 37 a of the magnetic pole tooth unit 37 is fitted into the fitting groove 35 a of the base portion 35 . In the base portion 35, the length of the mover 2 in the movable direction may be set according to the length of the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 in the movable direction. The fixing between the base portion 35 and the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 is performed as follows. After applying an adhesive to one or both of the fitting groove 35a and the fitted portion 361a or the fitted portion 371a, fitting is performed. Thereby, the base portion 35 and the magnetic pole tooth unit 36 or the magnetic pole tooth unit 37 are fixed. As a result, the back yoke unit 301 or the back yoke unit 302 is formed. By selecting the number of back yoke units 301 according to the stroke of the linear motor 1 and connecting a plurality of back yoke units 301 and one back yoke unit 302, the back yoke 3 can be formed as shown in FIG. It is formed. The respective back yoke units 301 and 302 may be connected by a known method, for example, the back surfaces of the back yoke units 301 and 302 may be fixed with a rectangular plate member.

In the linear motor 1 according to the second modification, the magnetic pole tooth units 36 and 37 are constructed by laminating silicon steel plates (magnetic pole tooth pieces 361 and 371). In the linear motor 1 , in addition to the magnetic pole teeth 31 , a portion of the back yoke 3 connected to the magnetic pole teeth 31 in the thickness direction has a laminated structure. Therefore, the magnetic flux flowing through the connecting portions 361b and 371b between the adjacent magnetic pole teeth 31 is parallel to the surfaces of the magnetic pole teeth 361 and 371. As shown in FIG. The direction of eddy currents generated by the flow of magnetic flux is the direction of penetrating the plate surfaces of the magnetic pole teeth 361 and 371 . However, due to gaps between the surfaces of the magnetic pole teeth 361 and 371 and oxide films formed on the surfaces, the electrical resistance in the eddy current direction at the connection portions 361b and 371b is greater than in the case where the laminated structure is not used. . Therefore, it is possible to reduce the eddy current flowing through the connecting portions 361b and 371b. Therefore, the eddy current flowing through the back yoke 3 can be further reduced.

Moreover, in the second modification, in addition to the above-described effects of the basic example 1, the following effects are obtained. Since the base portion 35, which is a part of the back yoke 3, can be made of a non-magnetic material, it can be made of a material with a high Young's modulus, such as alumina. As a result, the rigidity of the back yoke 3 as a whole is increased, so that bending caused by the attraction force generated between the back yoke 3 and the mover 2 can be reduced. Furthermore, when the rigidity of the back yoke 3 as a whole exceeds the required rigidity due to the material of the base portion 35, the thickness of the back yoke 3 can be reduced. Further, in the second modification, the stroke of the linear motor 1 can be changed by making the number of the back yoke units 301 included in the back yoke 3 variable.

Although five magnetic pole teeth 31 are provided in each of the back yoke units 301 and 302, the present invention is not limited to this. Although the base portion 35 is provided with one magnetic pole tooth unit 36 or one magnetic pole tooth unit 37, it is not limited to this. Although the magnetic pole tooth unit 36 and the magnetic pole tooth unit 37 are each provided with the same number of magnetic pole teeth 31, the present invention is not limited to this.

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

38B is a perspective view showing a configuration example of the base portion 33. FIG. The base portion 33 shown in FIG. 38B is vertically inverted from the base portion 33 shown in FIG. 38A. The base portion 33 has a plurality of dovetail grooves (fitting grooves) 33a formed in a rectangular plate material. The dovetail groove 33a has a shape corresponding to the fitted portions 36a and 37a of the magnetic pole tooth units 36 and 37, respectively. After the back yoke 3 is fitted into the dovetail groove 33a of the base portion 33 and into the fitted portions 36a and 37a of the magnetic pole tooth units 36 and 37, the back yoke 3 is fixed with an adhesive or the like. The base portion 33 is made of a non-magnetic material.

In the third modified example, in addition to the above-described effects of the basic example 1, the following effects are obtained. The base portion 33, which is part of the back yoke 3, can be made of a non-magnetic material with a high Young's modulus, such as alumina. As a result, the rigidity of the back yoke 3 as a whole is increased, so that bending caused by the attraction force generated between the back yoke 3 and the mover 2 can be reduced.

In the basic example and the first to third modifications described above, the gaps between the adjacent magnetic pole teeth 31 may be filled with a non-magnetic material such as a resin mold. As a result, the strength of the back yoke 3 is increased, and the bending of the back yoke 3 due to the attraction force generated between it and the mover 2 can be suppressed more effectively.

The base plate 32 in the basic example described above may have a laminated structure partially in the direction (thickness direction) opposite to the direction in which the magnetic pole teeth 31 protrude from the roots of the magnetic pole teeth 31 . In other words, the magnetic pole teeth 31 (protrusions 31a, 31a) having a laminated structure may be engaged with the concave portions 32a, 32a in the laminated structure portion of the base plate 32 having a partially laminated structure. As a result, eddy current due to the magnetic flux flowing in the moving direction of the mover 2 can be suppressed, as in the first and second modifications.

The technical features (components) described in each embodiment can be combined with each other, and new technical features can be formed by combining them. The embodiments disclosed this time are illustrative in all respects and should be considered not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the meaning described above, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

1 linear motor 2 mover 3 back yoke 4 armature 21 permanent magnet 22 holding frame 23 fixed plate 31 magnetic pole tooth 32 base plate 33 base portion 34 magnetic pole tooth block 35 base portion 36 magnetic pole tooth unit 37 magnetic pole tooth unit 41 core 42 magnetic pole tooth 43 drive coil 221 hole 301 back yoke unit 302 back yoke unit 311 magnetic pole piece 341 magnetic pole tooth piece 361 magnetic pole tooth piece 371 magnetic pole tooth piece

Claims (5)

A mover having a magnet arrangement in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator disposed facing the mover with a gap therebetween, and the back yoke with a gap between the mover. has an armature as a stator arranged opposite to the opposite side,
The magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the magnetization directions of adjacent permanent magnets are opposite to each other,
The armature has a plurality of magnetic pole teeth, each of which is wound with a drive coil, at an equal pitch,
The back yoke has a plurality of magnetic pole teeth, on the surface facing the mover, at the same position as the magnetic pole teeth of the armature in the moving direction of the mover, and having no drive coil wound thereon. and
A linear motor, wherein the magnetic pole teeth of the back yoke are formed by stacking a plurality of plate members in a direction intersecting the moving direction of the mover. A part of the back yoke in a direction opposite to the direction in which the magnetic pole teeth protrude from the root of the magnetic pole teeth is formed by stacking a plurality of plate-like members in the stacking direction of the magnetic pole teeth,
2. The linear motor according to claim 1, wherein the plate member forming the laminated portion of the back yoke and the plate member forming the magnetic pole teeth are integrated. 3. The linear motor according to claim 1, wherein said plurality of plate-shaped members are subjected to insulation treatment on the laminated surfaces. 2. The mover has a holding member that holds the magnet array, and the holding member has a plurality of holes into which the plurality of permanent magnets are inserted respectively. 3. The linear motor according to any one of 3. 5. The linear motor according to claim 4, wherein the mover has a plate-like base member to which the holding member and the plurality of permanent magnets are adhered and fixed.

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