JP2018050430A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor capable of largely reducing a suction force while achieving a small construction and the occurrence of a large thrust.SOLUTION: A linear motor comprises: a magnet arrangement 2 as a movable element in which a plurality of rectangle permanent magnets 21 are arranged; a back yoke 3 as a stator oppositely arranged with a gap in the magnet arrangement 2; and an armature 4 as a stator oppositely arranged to the side opposite to the back yoke 3 with the gap in the magnet arrangement 2. A magnetization direction of each permanent magnet 21 is a thickness direction. The magnetization direction of both adjacent permanent magnets 21 is inversely directed. The armature 4 includes a plurality of magnetic pole teeth 42 to which a driving coil 43 is winded in an equal pitch. The back yoke 3 includes a plurality of magnetic pole teeth 31 in a surface opposite to the magnet arrangement 2 at the same position in the movable direction with the magnetic pole teeth 42.SELECTED DRAWING: Figure 2

Description

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

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

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

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

  Further, unlike the above-described linear motor, there has been proposed a linear motor in which only the magnet arrangement functions as a mover and the back yoke functions as a stator (Patent Documents 2 to 4, etc.).

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

JP 2005-269822 A JP 2005-117856 A JP-A-2015-130754 Japanese Patent Laid-Open No. 10-290560

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

  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, etc.), this attractive force is usually several times to ten times or more than the rated thrust. . Therefore, there is a problem that the mover is bent by a large suction force. As a result, the dimensional accuracy of a processing machine using a linear motor in which such bending occurs is deteriorated. Further, it is necessary to increase the rigidity of the mover, and there is a problem that the configuration is increased in size.

  In addition, since the excessive attractive force is also exerted on the linear guide that holds the magnet arrangement, the linear guide needs to have a large rated load so that it can withstand this excessive attractive force. Is inevitable.

  Therefore, it is desirable to reduce the above suction force. However, when reducing the suction force, it is necessary to realize both a small configuration and generation of a large thrust.

  In a linear motor (separated linear motor: Patent Documents 2 to 4 and the like) configured to move only the magnet array by separating the magnet array and the flat back yoke, the back yoke and the armature are included in the magnet array. Therefore, the entire suction force is smaller than that of the integrated linear motor. However, in the separation type linear motor, the magnetic pole area facing the magnet arrangement is only the area of the opposing magnetic pole teeth on the armature side, whereas it is almost the same as the area of all the magnets on the back yoke side. Therefore, when the magnetic flux density in both gaps is the same, a larger attractive force acts on the back yoke side according to the ratio of the magnetic pole area, so that the overall attractive force is greatly reduced. Can't hope.

  Therefore, the gap between the magnet array and the back yoke is widened to reduce the magnetic flux density of the gap, and the attractive force between the magnet array and the back yoke is reduced to the same extent as the attractive force between the magnet array and the armature. It is possible. However, when the gap between the magnet array and the back yoke is widened, the magnetic flux density for generating the thrust from the armature also decreases, and there is a problem that the thrust becomes small.

  Therefore, in the separation type linear motors such as Patent Documents 2 to 4 proposed so far, there is a problem that a reduction in thrust is unavoidable in order to reduce the attractive force of the mover.

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

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

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

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

  In addition, the uneven shape due to the formation of the magnetic pole teeth on the back yoke causes a shear region of the driving magnetic flux to be 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 a decrease in thrust due to an increase in the gap (air gap) with the magnet arrangement in two places, and a large thrust as a whole can be obtained. Therefore, the attractive force of the magnet arrangement (mover) can be greatly reduced while maintaining a large thrust.

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

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

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

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

  The linear motor according to the present invention is characterized in that a length of the magnet array is shorter than a length of the armature.

  In the linear motor of the present invention, the length of the magnet array is shorter than the length of the armature. Therefore, it is a small configuration and a large acceleration can be secured.

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

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

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

It is a perspective view which shows the structure of the linear motor of this invention. It is a side view which shows the structure of the linear motor of this invention. It is a side view which shows the flow of the magnetic flux in the linear motor of this invention. It is a top view which shows the structure of the magnet arrangement | sequence (movable element) in the linear motor of an Example. It is a disassembled perspective view which shows the structure of the magnet arrangement | sequence (movable element) in the linear motor of an Example. It is a figure which shows the side shape of the back yoke in the linear motor of an Example. It is a top view which shows the armature raw material used for preparation of the armature in the linear motor of an Example. It is a figure which shows the winding of the armature in the linear motor of an Example. It is a figure which shows the structure of the linear motor of an Example. It is a graph which shows the thrust fluctuation | variation with respect to the electrical angle of the linear motor of an Example. It is a graph which shows the thrust characteristic of the linear motor of an Example. It is a graph which shows the attraction force characteristic of the linear motor of an Example. It is a side view which shows the structure of the linear motor of the 1st prior art example (structure which integrated the magnet arrangement | sequence and the back yoke into the needle | mover). It is a figure which shows the structure of the linear motor of a 1st prior art example. It is a side view which shows the structure of the linear motor of the 2nd prior art example (structure which used only the magnet arrangement | sequence as a needle | mover and used the flat back yoke as a stator). It is a figure which shows the structure of the linear motor of a 2nd prior art example. It is a graph which shows the average thrust in the linear motor of a 1st prior art example, a 2nd prior art example, and an Example. It is a graph which shows the average suction | attraction force in the linear motor of a 1st prior art example, a 2nd prior art example, and an Example. It is a graph which shows the thrust characteristic of the linear motor of another Example. It is a graph which shows the attractive force characteristic of the linear motor of another Example. It is a graph which shows the thrust characteristic of the linear motor of other Example. It is a graph which shows the attractive force characteristic of the linear motor of other Example.

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

  1 and 2 are a perspective view and a side view showing the configuration of the linear motor of the present invention. The linear motor 1 includes a long magnet array 2, a back yoke 3 disposed opposite to the magnet array 2 with a gap therebetween, and an armature 4 disposed opposite to the back yoke 3 with a gap disposed between the magnet arrays 2. And have. Only the magnet array 2 functions as a mover, and the back yoke 3 and the armature 4 function as a stator. The linear motor 1 is a 7-pole 6-slot linear motor. In FIG. 2, only the magnet arrangement 2 represents a cross section from a direction parallel to the movable direction so that the arrangement of the magnets can be understood.

  The lengths of the back yoke 3 and the armature 4 in the movable direction (left-right direction in FIG. 2) are substantially equal, and the length of the magnet array 2 (movable element) in the movable direction (left-right direction in FIG. 2) is the length of these back yokes. 3 and the length of the armature 4, and the difference in length is an operable stroke of the linear motor 1.

  The magnet array 2 is configured by supporting and fixing a plurality of rectangular permanent magnets 21 on a support frame 22 made of a non-magnetic material at an equal pitch and juxtaposed in a movable direction (left and right direction in FIG. 2). Each permanent magnet 21 is magnetized in the thickness direction (vertical direction in FIG. 2), and the magnetization directions of the adjacent permanent magnets 21 and 21 are opposite to each other. That is, in the magnet arrangement 2, 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. Is arranged.

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

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

  The pitch of the magnetic pole teeth 31 in the back yoke 3 is equal to the pitch of the magnetic pole teeth 42 of the armature 4, and the position of each magnetic pole tooth 31 in the back yoke 3 is the position of the armature 4 in the moving direction of the magnet array 2 (movable element). The position of each magnetic pole tooth 42 is the same. Further, the shape of the magnetic pole surface facing the magnet array 2 of the magnetic pole teeth 31 of the back yoke 3 has a rectangular shape substantially the same as the magnetic pole surface of the armature 4 facing the magnet array 2 of the magnetic pole teeth 42, The former magnetic pole area is 0.9 to 1.1 times the latter magnetic pole area. For example, the magnetic pole surface of the magnetic pole tooth 31 and the magnetic pole surface of the magnetic pole tooth 42 have the same rectangular shape and the same area. Further, the gap between the magnet array 2 and the back yoke 3 is the same as or larger than the gap between the magnet array 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 the linear motor 1 of the present invention, the surface of the back yoke 3 facing the magnet array 2 has a magnetic pole surface having substantially the same shape at the same position in the movable direction as the magnetic pole teeth 42 of the armature 4. Are formed with the same magnetic pole teeth 31. Therefore, the magnitude of the attractive force generated between the magnet array 2 and the back yoke 3 and the magnitude of the attractive force generated between the magnet array 2 and the armature 4 are substantially equal to each other. Is effectively canceled out, and the attractive force of the mover as the whole linear motor 1 becomes very small. Thus, in the linear motor 1 of the present invention, the attractive force can be significantly reduced without increasing the gap between the magnet array 2 and the back yoke 3. Therefore, it is not necessary to increase the gap between the magnet array 2 and the back yoke 3, so that the thrust is not reduced.

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

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

  From the above, in the linear motor 1 of the present invention, the attractive force of the mover (magnet array 2) can be greatly reduced while maintaining a large thrust. Therefore, the magnet array 2 hardly undergoes bending due to the attractive force, and the dimensional accuracy in a processing machine or the like in a semiconductor manufacturing apparatus using the linear motor 1 becomes very high.

  Moreover, in the linear motor 1 of the present invention, since the attractive force can be reduced, there is no problem even if the permanent magnet 21 and the support frame 22 having low rigidity are used. Therefore, it is possible to reduce the size of the mover (magnet array 2) and to realize a large acceleration as the mover (magnet array 2) becomes lighter. Further, since the mover (magnet array 2) is less worn, 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. However, in the linear motor 1 of the present invention, the suction force becomes small. Linear guides with low rigidity can be used, and this also contributes to miniaturization and longer life of linear motors.

  In the linear motor 1 of the present invention, the length of the magnet array 2 (mover) is shorter than the length of the back yoke 3 and the armature 4 (stator), thereby further reducing the size, weight, and speed. I am trying.

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

  First, magnet array 2 (mover) was produced. FIG.4 and FIG.5 is the top view and exploded perspective view which show the structure of the magnet arrangement | sequence 2 (movable element) in the linear motor 1 of an Example.

14 rectangular permanent magnets 21 having a thickness of 5 mm, a width of 12 mm, and a length of 82 mm were cut out from a block of Nd-Fe-B rare earth magnet (B _r = 1.395 T, H _cJ = 1273 kA / m). . The cut out permanent magnet 21 was magnetized in the thickness direction. Next, the support frame 22 as shown in FIG. 5 was cut out by wire cutting from an aluminum plate having a thickness of 5 mm. Then, 14 permanent magnets 21 are inserted into the cut support frame 22 with a skew angle of 3.2 ° so that the magnetization directions of the adjacent permanent magnets 21 are opposite to each other, and bonded. Thus, magnet array 2 (mover) was produced.

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

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

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

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

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

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

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

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

  FIGS. 9A and 9B are diagrams showing the configuration of the linear motor 1 of the embodiment produced in this way, FIG. 9A is a top view thereof, and B is a side view thereof. In FIG. 9B, the white arrow indicates the magnetization direction of the permanent magnet 21, and the solid arrow indicates the movable direction of the magnet array 2 (movable element). The details of the production specifications of the linear motor 1 are as follows.

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

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

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

  The assembled linear motor 1 is placed on a thrust measurement test bench and driven by a three-phase constant current power source synchronized with the position of the mover (magnet array 2) to move the mover (magnet array 2). The thrust and suction force were measured.

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

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

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

  By the way, in order to evaluate the linear motor 1 of the present invention in comparison with the conventional linear motor, two types of linear motors (first conventional example and second conventional example) are produced as conventional examples, and their characteristics ( Thrust and suction force) were measured.

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

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

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

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

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

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

  Next, the configuration of the second conventional example will be described. FIG. 15 is a side view showing the configuration of the linear motor of the second conventional example. The second conventional example is a linear motor (separated linear motor) having a configuration according to Patent Documents 2 to 4. In FIG. 15, only the magnet array 62 represents a cross section from a direction parallel to the movable direction so that the arrangement of the magnets can be understood.

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

  The configuration of the magnet array 62 is the same as the configuration of the magnet array 2 described above. That is, the magnet array 62 is configured by supporting and fixing a plurality of rectangular permanent magnets 65 on a support frame made of a non-magnetic material at an equal pitch and installing them in a movable direction (left-right direction in FIG. 15). 65 is magnetized in the thickness direction (vertical direction in FIG. 15), and the magnetization directions of the adjacent permanent magnets 65, 65 are opposite to each other. The back yoke 63 made of mild steel has a flat plate shape not only on the surface not facing the magnet array 62 but also on the surface facing the magnet array 62, and there are magnetic pole teeth like the linear motor 1 of the present invention. do not do. The configuration of the armature 64 is the same as the configuration of the armature 4 described above, and a plurality of magnetic pole teeth 67 are integrally provided on the core 66 at an equal pitch in the movable direction. The drive coil 68 is wound on the front.

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

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

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

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

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

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

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

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

  By the way, in the linear motor 1 of this invention, as shown also in FIG. 12, the magnitude | size of attraction force changes with the magnitude | sizes of a drive magnetomotive force. Therefore, if the size of the gap between the magnet array 2 and the back yoke 3 is adjusted in accordance with a frequently used thrust region (drive magnetomotive force), the attractive force can be further reduced.

  In the embodiment described above, the gap between the magnet array 2 and the back yoke 3 and the gap between the magnet array 2 and the armature 4 are both equal to 0.5 mm. The gap between the armature 4 and the armature 4 remains 0.5 mm, and the gap between the magnet array 2 and the back yoke 3 is 0.74 mm. Other configurations are the same as those in the above-described embodiment.

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

  In another embodiment, the thrust is 978 N when the driving magnetomotive force is 1200 A, which is a little lower than the above-described embodiment, but the attractive force is only 18 N when the driving magnetomotive force is 1200 A. Almost zero can be realized. This is a suction force at which the linear guide, the mover, and the surrounding structure can be ignored due to the deformation and life reduction due to the suction force. Therefore, when used with a driving magnetomotive force in the vicinity of 1200 A, it can be seen that the linear motor 1 of the other embodiment is more suitable for the purpose of reducing the attractive force than the embodiment described above. .

  As still another example, a linear motor 1 was manufactured in which the gap between the magnet array 2 and the armature 4 remained 0.5 mm and the gap between the magnet array 2 and the back yoke 3 was 0.66 mm. Other configurations are the same as those in the above-described embodiment.

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

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

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

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

  In the above-described embodiment, the linear motor 1 having the configuration in which the magnet array 2 (movable element) is shorter than the armature 4 has been described. On the contrary, the configuration in which the magnet array (movable element) is longer than the armature. The features of the present invention (formation of magnetic pole teeth on the back yoke) can also be applied to this linear motor.

  The disclosed embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Linear motor 2 Magnet arrangement (mover)
3 Back yoke 4 Armature 21 Permanent magnet 22 Support frame 31 Magnetic pole teeth 41 Core 42 Magnetic pole teeth 43 Drive coil

Claims (4)

A magnet arrangement as a mover in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator arranged to face the magnet arrangement with a gap, and the back yoke with a gap in the magnet arrangement Has an armature as a stator arranged opposite to the opposite side,
The magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the magnetization directions of adjacent permanent magnets are opposite to each other,
The armature has a plurality of magnetic pole teeth each having a drive coil wound at an equal pitch,
The back yoke has a plurality of magnetic pole teeth at the same position in a movable direction of the magnet arrangement and the magnetic pole teeth of the armature on a surface facing the magnet arrangement,
The magnetic pole area of the magnetic pole teeth in the back yoke is 0.9 to 1.1 times the magnetic pole area of the magnetic pole teeth in the armature, and the gap between the magnet arrangement and the back yoke is the magnet arrangement and the Linear motor characterized by being equal to or larger than the gap with the armature.   2. The linear motor according to claim 1, wherein the height of the magnetic pole teeth in the back yoke is not less than 1/20 times and not more than twice the pitch of the magnetic pole teeth.   The linear motor according to claim 1, wherein a length of the magnet array is shorter than a length of the armature.   4. The size of the gap between the magnet arrangement and the back yoke and / or the size of the gap between the magnet arrangement and the armature are variable. The linear motor described in 1.

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