JP6790656B2 - Linear motor - Google Patents

Description

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

Conventionally, a method of converting the output of a rotary motor into linear motion with a ball screw has been used for X and Y movement, but since the moving speed is slow, a linear motor capable of directly extracting the linear motion output is used. It is being used. A linear motor is generally configured by combining a mover having a plurality of rectangular permanent magnets and an armature having a plurality of magnetic pole teeth.

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

This type of linear motor includes a mover having a magnet array in which a plurality of permanent magnets are arranged and a flat back yoke integrated into the magnet array, and an armature in which a drive coil is wound around a plurality of magnetic pole teeth. Are opposed to each other with a gap. By energizing the drive coil, 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-mentioned linear motor, a linear motor in which only the magnet arrangement functions as a mover and the back yoke functions as a stator has been proposed (Patent Documents 2 to 4 and the like).

In this type of linear motor, the magnet arrangement and the flat plate-shaped back yoke are separated, and the back yoke is made to face the magnet arrangement with a gap on the opposite side of the armature so that only the magnet arrangement can be moved. Only the magnet array moves, 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 operable stroke of the linear motor.

Japanese Unexamined Patent Publication No. 2005-269822 Japanese Unexamined Patent Publication No. 2005-117856 JP-A-2015-130754 Japanese Unexamined Patent Publication No. 10-290560

The mover is strongly attracted to the magnetic pole tooth surfaces of the opposing armatures. 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 magnetic pole teeth of the electrode element, S: there is opposition between the mover and the armature.
Effective area, μ ₀ : Vacuum permeability)

In a linear motor having a mover in which a magnet arrangement and a flat plate-shaped back yoke are integrated (integrated linear motor: Patent Document 1, etc.), this attractive force is usually several to ten times or more the rated thrust. .. Therefore, there is a problem that the mover bends due to a large suction force. As a result, the dimensional accuracy of the processing machine using the linear motor in which such bending occurs deteriorates. Further, it is necessary to increase the rigidity of the mover, which has a drawback that the configuration becomes large.

In addition, since the excessive attractive force is also applied to the linear guide that holds the magnet arrangement, the linear guide needs to have a large rated load so as to withstand this excessive attractive force, and in this respect as well, the configuration is increased. Is inevitable.

Therefore, it is desired to reduce the suction force as described above. However, when reducing the suction force, it is necessary to be able to realize both a small configuration and a large thrust generation.

In a linear motor (separate linear motor: Patent Documents 2 to 4, etc.) in which the magnet arrangement and the flat plate-shaped back yoke are separated and only the magnet arrangement is moved, the back yoke and the armature are included in the magnet arrangement. Since the suction force acts from both sides, the overall suction force is smaller than that of the integrated linear motor. However, in the separated linear motor, the area of the magnetic poles facing the magnet arrangement is only the area of the opposing 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 densities in both gaps are the same, a larger attractive force acts on the back yoke side according to the ratio of the magnetic pole areas, so that the overall attractive force is significantly reduced. I can't hope for it.

Therefore, the gap between the magnet arrangement and the back yoke is widened to reduce the magnetic flux density of the gap, and the attractive force between the magnet arrangement and the back yoke is reduced to the same level as the attractive force between the magnet arrangement and the armature. Can be considered. However, when the gap between the magnet arrangement and the back yoke is widened, the magnetic flux density for generating the thrust from the armature also decreases, so that there is a problem that the thrust becomes small.

Therefore, the separate linear motors such as Patent Documents 2 to 4 proposed so far have a problem that a decrease in thrust is unavoidable in order to reduce the suction 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. ..

The linear motor according to the present invention has a magnet arrangement as a mover in which a plurality of rectangular permanent magnets are arranged, a back yoke as a stator arranged with a gap in the magnet arrangement, and the magnet arrangement. It is provided with an armature as a stator that is arranged opposite to the back yoke with a gap, and the magnetization direction of each of the plurality of permanent magnets is the thickness direction, and the permanent magnets adjacent to each other are magnetized. The magnetizing directions are opposite, and the armature has a plurality of magnetic pole teeth on which drive coils are wound at equal pitches, and the back yoke is placed on a surface facing the magnet arrangement. It has a plurality of magnetic pole teeth in which the drive coil is not wound at the same position in the movable 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 the above. It 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 equal to or larger than the gap between the magnet arrangement and the armature. It is a feature.

In the linear motor of the present invention, a magnet array in which a plurality of permanent magnets are arranged, a back yoke arranged so as to face the magnet array with a gap, and a back yoke facing the magnet array with a gap on the opposite side of the back yoke. It has an arranged armature. The magnet array functions as a mover, and the back yoke and armature function as stators. Each of the plurality of rectangular permanent magnets in the magnet arrangement is magnetized in the thickness direction, and the magnetization directions are opposite between the adjacent permanent magnets. The armature has a plurality of magnetic pole teeth at equal pitches, and a drive coil is wound around each magnetic pole tooth. The surface of the back yoke facing the magnet arrangement is not flat, and a plurality of magnetic pole teeth are formed at equal pitches. 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 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 arrangement and the back yoke is larger than the gap between the magnet arrangement 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 from the armature is applied is brought close to the magnet arrangement, and a gap from the magnet arrangement is provided except for the portion facing the magnetic pole teeth of the armature. Since the magnetic pole area of the armature facing the magnet arrangement and the magnetic pole area of the back yoke facing the magnet arrangement are substantially equal to each other, they cancel each other out efficiently, and the total attractive force is significantly reduced. Therefore, the attractive force can be significantly reduced without increasing the gap between the magnet arrangement and the back yoke. At this time, since it is not necessary to increase the gap between the magnet arrangement and the back yoke, the decrease in thrust is small.

Further, since the sheared region of the driving magnetic flux is generated in the back yoke due to the uneven shape due to the formation of the magnetic pole teeth on the back yoke, not only the armature but also the back yoke contributes to the generation of thrust. This thrust generation compensates for the decrease in thrust caused by the increase in the gap (air gap) with the magnet arrangement at two locations, and a large thrust as a whole can be obtained. Therefore, the attractive force of the magnet arrangement (movable element) can be significantly reduced while maintaining a large thrust.

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 to increase the attractive force, while if the magnetic pole area of the magnetic pole teeth of the back yoke is too narrow, thrust is obtained. The magnetic flux for this 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 magnetic pole teeth of the armature, the magnetic pole teeth of the armature are not configured so low, and the height of the magnetic pole teeth of the armature is higher than the height of the magnetic pole teeth in 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 a portion other than the magnetic pole teeth, and the attractive force tends to be larger than that on the armature side. Therefore, the gap between the magnet arrangement and the back yoke is equal to or larger than the gap between the magnet arrangement and the armature so that the attractive force can be efficiently offset.

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 or more and 2 times or less 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 made too small compared to the pitch, the effect of providing the magnetic pole teeth (concave and convex shape) cannot be obtained, while the magnetic pole teeth. If the height of the magnet is made too large compared to the pitch, the effect will not change and it will go against the miniaturization. Therefore, the height of the magnetic pole teeth in the back yoke is set to 1/20 or more and 2 times or less the pitch of the magnetic pole teeth.

The linear motor according to the present invention is characterized in that the length of the magnet array is shorter than the 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 has a small configuration and can secure a large acceleration.

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 size of the driving magnetomotive force during use, the attractive force is almost zero. It is possible to.

In the linear motor of the present invention, the attractive force of the magnet arrangement (movable element) can be significantly reduced while realizing a compact configuration and generation of a large thrust. Therefore, deformation due to bending due to a large suction force can be suppressed, and deterioration in dimensional accuracy of the device in which the linear motor is used can be prevented. Since the attractive force can be reduced, the rigidity of the magnet arrangement (movable element) and the rigidity of the support system that supports the magnet arrangement (movable element) can be reduced. Can be improved. In addition, by providing the magnetic pole tooth structure on the back yoke, the thrust from the back yoke is applied to the magnet arrangement (movable element), so that the thrust is reduced due to the provision of a gap between the magnet arrangement and the back yoke. It 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 (movable element) in the linear motor of an Example. It is an exploded perspective view which shows the structure of the magnet arrangement (movable element) in the linear motor of an Example. It is a figure which shows the side surface shape of the back yoke in the linear motor of an Example. It is a top view which shows the armature material used for manufacturing 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 variation with respect to the electric 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 suction 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 conventional example (the structure which integrated the magnet arrangement and the back yoke into a mover). It is a figure which shows the structure of the linear motor of the 1st conventional example. It is a side view which shows the structure of the linear motor of the 2nd conventional example (the structure which used only the magnet arrangement as a mover, and the flat back yoke as a stator). It is a figure which shows the structure of the linear motor of the 2nd conventional example. It is a graph which shows the average thrust in the linear motor of the 1st conventional example, the 2nd conventional example, and an Example. It is a graph which shows the average suction force in the linear motor of the 1st conventional example, the 2nd conventional 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 suction force characteristic of the linear motor of another Example. It is a graph which shows the thrust characteristic of the linear motor of still another Example. It is a graph which shows the suction force characteristic of the linear motor of still another Example.

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

1 and 2 are perspective views and side views 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 arranged to face the magnet array 2 with a gap, and an armature 4 arranged to face the magnet array 2 with a gap on the opposite side of the back yoke 3. And have. Only the magnet array 2 functions as a mover, and the back yoke 3 and the armature 4 function as stators. The linear motor 1 is a 7-pole 6-slot type linear motor. In FIG. 2, only the magnet array 2 represents a cross section from a direction parallel to the movable direction so that the arrangement of the magnets can be seen.

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 lengths of the magnet arrangement 2 (movable element) in the movable direction (left-right direction in FIG. 2) are these back yokes. It is shorter than the length of the armature 3 and the armature 4, and the difference in length is the operable stroke of the linear motor 1.

The magnet array 2 is configured by supporting and fixing a plurality of rectangular permanent magnets 21 to a support frame 22 made of a non-magnetic material at equal pitches and juxtaposing them in a movable direction (horizontal 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 toward the armature 4 side and the permanent magnets 21 magnetized in the direction from the armature 4 side toward the back yoke 3 side alternate. It is located in.

The surface of the back yoke 3 made of mild steel, preferably a soft magnetic material (for example, a silicon steel plate), which does not face the magnet arrangement 2 is flat, but the surface of the back yoke 3 which faces the magnet arrangement 2 is flat. A plurality of rectangular magnetic pole teeth 31 are formed at equal pitches in the movable direction instead of being flat. The height of each magnetic pole tooth 31 is 1/20 times or more and 2 times or less, preferably 1/10 times or more and 1 times or less of the formation pitch of the magnetic pole teeth 31. For example, the height of each magnetic pole tooth 31 is about half of the forming pitch of the magnetic pole tooth 31.

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

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 magnetic pole teeth 31 of the armature 4 in the moving direction of the magnet arrangement 2 (movable element). It is the same as the position of each magnetic pole tooth 42. Further, the shape of the magnetic pole surface of the magnetic pole teeth 31 of the back yoke 3 facing the magnet arrangement 2 is a rectangular shape having substantially the same shape as the magnetic pole surface of the magnetic pole teeth 42 of the armature 4 facing the magnet arrangement 2. 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 surface of the magnetic pole tooth 31 and the magnetic pole surface of the magnetic pole tooth 42 have the same rectangular shape and have the same area. Further, the gap between the magnet arrangement 2 and the back yoke 3 is the same as or larger than the gap between the magnet arrangement 2 and the armature 4. For example, the latter gap is 0.5 mm, and the former gap is 0.5 mm or more.

The linear motor 1 of the present invention has a magnetic pole area having substantially the same shape as the magnetic pole teeth 42 of the armature 4 at the same position in the movable direction on the surface of the back yoke 3 facing the magnet arrangement 2. Form the magnetic pole teeth 31 which are substantially the same. Therefore, the magnitude of the attractive force generated between the magnet arrangement 2 and the back yoke 3 and the magnitude of the attractive force generated between the magnet arrangement 2 and the armature 4 are substantially equal to each other, and both attractive forces are in the vertical direction of FIG. Is effectively offset, so that the suction force of the mover as a whole of the linear motor 1 becomes very small. As described above, in the linear motor 1 of the present invention, the attractive force can be significantly reduced without increasing the gap between the magnet arrangement 2 and the back yoke 3. Therefore, it is not necessary to increase the gap between the magnet arrangement 2 and the back yoke 3, so that the thrust does not decrease.

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 shear region of the driving magnetic flux is generated due to the uneven shape facing the magnet arrangement 2, so that only the armature 4 is used. 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, the arrows indicate the flow of magnetic flux. In the linear motor 1, thrust is generated by shearing the magnetic flux on the armature 4 side, and thrust is also generated by shearing the magnetic flux on the back yoke 3 side. The thrust generated in the linear motor 1 is both of these thrusts. Is the sum of. 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, only the thrust due to the shearing of the magnetic flux on the armature side. ..

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

From the above, in the linear motor 1 of the present invention, the attractive force of the mover (magnet arrangement 2) can be significantly reduced while maintaining a large thrust. Therefore, the magnet array 2 hardly bends 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.

Further, 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 arrangement 2) and to realize a large acceleration as the mover (magnet arrangement 2) becomes lighter. Further, since the mover (magnet arrangement 2) is less worn, the life of the linear motor 1 can be extended.

In a linear motor, in order to smoothly move the mover, it is common to provide a linear guide on the side surface of the mover as described later. However, in the linear motor 1 of the present invention, the suction force is small, so that the attraction force is small. A linear guide with low rigidity can be used, which also contributes to the miniaturization and long life of the linear motor.

In the linear motor 1 of the present invention, the length of the magnet array 2 (movable element) is made shorter than the length of the back yoke 3 and the armature 4 (stator) to further reduce the size, weight and speed. I'm trying.

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

First, a magnet array 2 (movable element) was produced. 4 and 5 are a plan view and an exploded perspective view showing a configuration of a magnet array 2 (movable element) in the linear motor 1 of the embodiment.

Nd-Fe-B based rare earth magnet _{(B r = 1.395T, H cJ} = 1273kA / m) from the block, a thickness of 5 mm, a width 12 mm, was cut out a rectangular fourteen permanent magnets 21 of length 82mm .. The cut out permanent magnet 21 was magnetized in the thickness direction. Next, a support frame 22 as shown in FIG. 5 was cut out from an aluminum plate having a thickness of 5 mm by wire cutting. Then, 14 permanent magnets 21 are arranged and inserted into the cut-out 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 the magnets are bonded to each other. A magnet array 2 (movable element) was produced.

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

A block having the dimensions shown in FIG. 6 is machined from mild steel (JIS standard G3101 type code 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, the armature 4 was manufactured. 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 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 code 50A800 material), and the cut out 164 pieces are stacked and the side surface is subjected to a CO ₂ laser. A block body with a width of 82 mm, a height of 31 mm, and a length of 263.04 mm (18 magnetic pole teeth 42 of the same shape (width: 6 mm, height: 25 mm, length: 82 mm, magnetic pole) on the core 41. An area of 492 mm ² ) having an equal pitch (15.12 mm)) was obtained.

Next, a winding was inserted into this block body. FIG. 8 is a diagram showing the winding of the armature 4 in the linear motor 1 of the embodiment. A drive coil 43 was formed by impregnating an arm portion of each magnetic pole tooth 42 of the armature 4 with an enamel-coated lead wire having a diameter of 2 mm wound 17 times and impregnating it with varnish.

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

Next, the produced back yoke 3 and armature 4 were fixed using a jig so that the distance between them was kept constant at 6 mm. The gap between the back yoke 3 and the armature 4 was fixed to be 6 mm, but this gap was adjusted after assembling the linear motor 1. Next, after attaching a linear guide (not shown) to the side surface of the magnet arrangement 2 (movable element), the back yoke 3 and the armature 4 are separated from each other by a predetermined distance in the gap between the back yoke 3 and the armature 4. , A magnet array 2 (movable element) having a thickness of 5 mm was inserted to manufacture a linear motor 1. At this time, the distance between the magnet arrangement 2 (movable element) and the magnetic pole teeth 31 of the back yoke 3 and the distance between the magnet arrangement 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 is provided between the linear guide and the armature 4 so that the suction force can be measured.

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

In addition, as a mechanism for adjusting the gap between the armature 4 and the linear guide supporting the movable element magnet arrangement 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 mechanism for adjusting the height by inserting a shim plate having a tapered cross section with a screw can be adopted.

9A and 9B are views showing the configuration of the linear motor 1 of the embodiment produced in this manner, FIG. 9A is a top view thereof, and FIG. 9B is a side view thereof. In FIG. 9B, the white arrow represents the magnetizing direction of the permanent magnet 21, and the solid arrow represents the moving direction of the magnet array 2 (movable element). The details of the manufacturing specifications of this linear motor 1 are as follows.

Magnetic pole configuration: 7 poles, 6 slots Material of permanent magnet 21: Nd-Fe-B type rare earth magnet (NMX-S49CH manufactured by Hitachi Metals)
Material)
Shape of permanent magnet 21: thickness 5.0 mm, width 12 mm, length 82 mm
Permanent magnet 21 pitch: 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 code 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 code 50A800 material)
Shape of magnetic pole teeth 42: width 6.0 mm, height: 25 mm, length: 82 mm
Pitch of magnetic pole teeth 42: 15.12 mm
Shape of drive coil 43: width 15.12 mm, height 23 mm, length 91.12 mm
Winding thickness of drive coil 43: 4.06 mm
Diameter of winding of drive coil 43, number of turns: diameter 2 mm, 17 turns winding resistance (1 piece): 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 arrangement 2 (movable element) is shorter than the length (both 263.04 mm) of the back yoke 3 and the armature 4. The pitch of the magnetic pole teeth 31 in the back yoke 3 and the pitch of the magnetic pole teeth 42 in the armature 4 are both equal to 15.12 mm, and the magnetic pole teeth 31 and the magnetic pole teeth 42 are in the same position in the movable direction.

The shape of the magnetic pole surface of the magnetic pole teeth 31 facing the magnet array 2 (movable element) and the shape of the magnetic pole surface of the magnetic pole teeth 42 facing the magnet array 2 (movable element) are rectangular shapes having the same dimensions. That is, the width of the magnetic pole teeth 31 (dimension in the movable direction) and the width of the magnetic pole teeth 42 (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 arrangement 2 (movable element). The area and the magnetic pole area of the magnetic pole teeth 42 facing the magnet arrangement 2 (movable element) are both 492 mm ² and are equal.

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 (magnet arrangement 2) to move the mover (magnet arrangement 2). , Thrust and suction force were measured.

FIG. 10 is a graph showing thrust fluctuations with respect to the electric angle of the linear motor 1 of the embodiment. This thrust fluctuation is the thrust (U phase, V phase, W phase 3) with respect to the position of the mover (magnet arrangement 2) when the drive magnetomotive force (= magnitude of drive current x number of turns of drive coil 43) is 1200 A. It represents the change in phase synthetic thrust). In FIG. 10, the horizontal axis is the electric angle [°] and the vertical axis is the thrust [N]. Further, a in the figure 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 (the combined thrust of the thrust by the armature 4 and the thrust by the back yoke 3). There is. As shown in FIG. 10, it can be seen that a large thrust that is substantially constant is obtained over the entire area.

FIG. 11 is a graph showing the thrust characteristics of the linear motor 1 of the embodiment. This thrust characteristic represents a 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 [N], and the right vertical axis is the thrust magnetomotive force ratio [N / A]. Further, a in the figure represents a thrust, and b in the figure represents a thrust-magnetomotive force ratio, respectively. 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 embodiment. This attractive force characteristic represents a characteristic when the current applied to the drive coil 43 is changed. In FIG. 12, the horizontal axis is the driving magnetomotive force [A], and the vertical axis is the attractive force [N]. The attractive force indicates that the mover (magnet arrangement 2) is attracted to the armature 4 side on the + side, and the mover (magnet arrangement 2) is attracted to the back yoke 3 side on the − side. The attractive force increases as the driving magnetomotive force increases. For example, when the driving magnetomotive force is 1200A, the mover (magnet arrangement 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 manufactured 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 has a mover 51 in which a magnet array 52 and a back yoke 53 are integrated, and an armature 54 arranged so as to face 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 2 described above. That is, the magnet arrangement 52 is configured by supporting and fixing a plurality of rectangular permanent magnets 55 to a support frame made of a non-magnetic material at equal pitches and installing them in a movable direction (left-right direction in FIG. 13). The 55 is magnetized in the thickness direction (vertical direction in FIG. 13), and the magnetizing directions of the adjacent permanent magnets 55 and 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 plate-shaped back yoke 53 made of mild steel. Further, 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 movable direction, and each magnetic pole tooth 57 is integrally provided. The drive coil 58 is wound around.

FIG. 14 is a diagram showing the configuration of such a linear motor 50 of the first conventional example, FIG. 14A is a top view thereof, and FIG. 14B is a side view thereof. In FIG. 14B, the white arrow represents the magnetizing direction of the permanent magnet 55, and the solid arrow represents the moving direction of the mover 51. The size of the gap between the mover 51 and the armature 54 was set to 0.5 mm or 1 mm. The details of the manufacturing specifications of the linear motor 50 are as follows.

Magnetic pole configuration: 7 poles, 6 slots Permanent magnet 55 material: Nd-Fe-B series rare earth magnet (Hitachi Metals NMX-S49CH)
Material)
Shape of permanent magnet 55: thickness 5.0 mm, width 12 mm, length 82 mm
Permanent magnet 55 pitch: 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 code 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 code 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
Shape of drive coil 58: width 15.12 mm, height 23 mm, length 91.12 mm
Winding thickness of drive coil 58: 4.06 mm
Diameter of winding of drive coil 58, number of turns: diameter 2 mm, 17 turns winding resistance (1 piece): 0.0189Ω
Mass of mover 51 (magnet array 52 + back yoke 53): 1321.01 g

The length of the mover 51 (integrated configuration of the magnet arrangement 52 and the back yoke 53) in the movable direction (left-right direction in FIG. 13) is shorter than the length of the armature 54, and the difference in length is that of the linear motor 50. It becomes a movable 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 according to Patent Documents 2 to 4. In FIG. 15, only the magnet array 62 shows a cross section from a direction parallel to the movable 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 back yoke 63 having a gap between the magnet arrangement 62 and arranged to face the back yoke 63. It has an armature 64. Only the magnet array 62 functions as a mover, and the back yoke 63 and the armature 64 function as stators.

The configuration of the magnet array 62 is the same as the configuration of the magnet array 2 described above. That is, the magnet arrangement 62 is configured by supporting and fixing a plurality of rectangular permanent magnets 65 to a support frame made of a non-magnetic material at equal pitches 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 magnetizing directions of the adjacent permanent magnets 65 and 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 has magnetic pole teeth like the linear motor 1 of the present invention. do not do. Further, 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 movable direction, and each magnetic pole tooth 67 is integrally provided. The drive coil 68 is wound around.

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

Magnetic pole configuration: 7 poles, 6 slots Permanent magnet 65 material: Nd-Fe-B series rare earth magnet (Hitachi Metals NMX-S49CH)
Material)
Shape of permanent magnet 65: 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 °
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 code 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 code 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
Shape of drive coil 68: width 15.12 mm, height 23 mm, length 91.12 mm
Winding thickness of drive coil 68: 4.06 mm
Diameter of winding of drive coil 68, number of turns: 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 (horizontal direction in FIG. 15) is shorter than the length of the armature 64, and the difference in length is the operable stroke of the linear motor 60.

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

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

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

The linear motor 50A (A in the figure) of the first conventional example has the largest thrust of 1030N, but the suction force is 4200N, which is about four times as large as the thrust. In the linear motor 50B (B in the figure) as a measure for reducing the suction force, the obtained thrust is remarkably reduced to 909N, whereas the suction force is 3360N without much reduction. Therefore, it is understood that the measures are not sufficient.

The linear motor 60 (C in the figure) of the second conventional example can obtain a relatively large thrust of 980 N, but the suction force is as large as 1712 N and is sucked to the back yoke 63 side. Not enough reduction has been made.

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

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

In the above-described embodiment, the gap between the magnet arrangement 2 and the back yoke 3 and the gap between the magnet arrangement 2 and the armature 4 are both equal to 0.5 mm, but in other examples, the gap is equal to that of the magnet arrangement 2. The gap between the armature 4 and the armature 4 remains 0.5 mm, and the gap between the magnet arrangement 2 and the back yoke 3 is 0.74 mm. The 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 is the driving magnetomotive force [A], the left vertical axis is the thrust [N], the right vertical axis is the thrust magnetomotive force ratio [N / A], a is the thrust, and b is the thrust magnetomotive force. Each represents a ratio. Further, in FIG. 20, the horizontal axis is the driving magnetomotive force [A], and the vertical axis is the attractive force [N].

In the other embodiment, the thrust is 978N when the driving magnetomotive force is 1200A, which is a little lower than that in the above-described embodiment, but the attractive force is only 18N when the driving magnetomotive force is 1200A. Almost zero has been achieved. This is a level of suction force at which deformation and life reduction due to suction force can be ignored on the linear guide, mover, and surrounding structures. Therefore, when used with a driving magnetomotive force near 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 above-described embodiment. ..

As yet another embodiment, a linear motor 1 was produced in which the gap between the magnet arrangement 2 and the armature 4 remained 0.5 mm, and the gap between the magnet arrangement 2 and the back yoke 3 was 0.66 mm. The 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 is the driving magnetomotive force [A], the left vertical axis is the thrust [N], the right vertical axis is the thrust magnetomotive force ratio [N / A], a is the thrust, and b is the thrust magnetomotive force. Each represents a ratio. Further, in FIG. 22, the horizontal axis is the driving magnetomotive force [A], and the vertical axis is the attractive force [N].

In yet another embodiment, the thrust is 984N when the driving magnetomotive force is 1200A, which is slightly lower than that in the above-described embodiment, but the attractive force is only 5N when the driving magnetomotive force is 600A. Has achieved almost zero. Therefore, it can be seen that the linear motor 1 of another embodiment is most suitable for reducing the attractive force when it is used with a driving magnetomotive force near 600 A.

From the above, by optimally setting the size of the gap between the magnet arrangement 2 and the back yoke 3 according to the frequently used area, the attractive force can be significantly 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 (magnet arrangement 2) and shortening of life due to an overload on the linear guide.

In the above-described embodiment, an example in which the size of the gap between the magnet arrangement 2 and the armature 4 is fixed and the size of the gap between the magnet arrangement 2 and the back yoke 3 is changed has been described, but the opposite is true. In addition, an example in which the size of the gap between the magnet arrangement 2 and the back yoke 3 is fixed and the size of the gap between the magnet arrangement 2 and the armature 4 is changed, 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 fixing the magnet array 2 and changing the position of the magnet array 2.

Further, in the above-described embodiment, the linear motor 1 having a configuration in which the magnet arrangement 2 (movable element) is shorter than the armature 4 has been described, but conversely, the magnet arrangement (movable element) has a longer configuration than the armature. The feature of the present invention (forming magnetic pole teeth on the back yoke) can also be applied to the linear motor of the above.

It should be noted that the disclosed embodiments are exemplary in all respects and are not considered to be restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Linear motor 2 Magnet arrangement (movable element)
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 with a gap in the magnet arrangement, and a back yoke with a gap in the magnet arrangement. Is equipped with an armature as a stator placed 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 on which drive coils are wound at equal pitches.
The back yoke has a plurality of magnetic pole teeth on the surface facing the magnet array, at the same positions as the magnetic pole teeth of the armature in the movable direction of the magnet array , each of which is not wound with a drive coil. And
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 said. A linear motor characterized by being equal to or greater than the clearance with the armature. The linear motor according to claim 1, wherein the height of the magnetic pole teeth in the back yoke is 1/20 times or more and 2 times or less the pitch of the magnetic pole teeth. The linear motor according to claim 1 or 2, wherein the length of the magnet array is shorter than the length of the armature. Any one of claims 1 to 3, wherein 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. The linear motor described in.

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