JP2008099379A - Low-profile linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems that a linear motor to be used for an X-Y stage for placing samples for an analysis instrument or various test equipment has a limitation in reduction in profile to obtain a desired thrust force, leaks a large number of magnetic fluxes and has low degree of freedom in assembling design. <P>SOLUTION: This linear motor has a configuration in which a pair of magnet arrays forming a mover are disposed with a formed predetermined gap, and an armature array forming a stator is disposed in the gap to allow a magnetic flux to be generated in a permanent magnet of each magnet array to efficiently act to armature core of the armature array, and yokes are disposed in the opposite side surface of an opposing surface of each magnet array to reduce leakage of magnetic flux. Thus, the low-profile linear motor enabling high thrust force and reduction in profile is realized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a linear motor used for a stage that is required to be thin, such as an X-Y stage for sample loading of analytical instruments and various inspection apparatuses. More preferably, the present invention relates to a thin linear motor used for an application such as an analytical instrument in which there is a concern about adverse effects on peripheral devices due to leakage of magnetic flux from the linear motor.

  In recent years, various structures have been proposed as linear motors used in specimen mounting X-Y stages of analytical instruments and various inspection apparatuses.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-7884) includes a stator in which a permanent magnet array in which a plurality of permanent magnets are arranged in a predetermined direction on a base, and a plurality of magnetic pole members fitted with coils. There has been proposed a structure having a mover that is arranged in a predetermined direction, has one end of the magnetic pole member disposed opposite to the permanent magnet row via a gap, and the other end is integrally fixed by a yoke. Yes. The permanent magnet is magnetized in a direction perpendicular to the permanent magnet arrangement surface of the base, and the magnetization directions of adjacent permanent magnets are alternately different.

Patent Document 2 (Japanese Patent Laid-Open No. 2006-54974) proposes a linear motor having a structure shown in FIG. 6 and realizing high thrust. This structure has a movable element 116 on both sides of the plate-like yoke 111.
And a pair of movers 116 on which an armature core 114 around which an armature coil 115 is wound is disposed so as to face each permanent magnet 112. Further, the armature core 114 is integrally connected with an end different from the end facing the permanent magnet 12 as shown in the figure. The permanent magnet 112 is magnetized in a direction perpendicular to the permanent magnet arrangement surface of the plate-like yoke 111, and the magnetization directions of the adjacent permanent magnets 112 are alternately different, and the permanent magnet 112 is interposed via the on-plate yoke 111. The two permanent magnets 112 facing each other have opposite magnetization directions.

  Patent Document 3 (Japanese Patent Laid-Open No. 2003-134792) proposes a linear motor having a structure shown in FIG. In this structure, in a linear motor composed of a field pole 204 composed of a pair of yokes 201, 202 in which a plurality of permanent magnets 203 are arranged and an armature (not shown), the opposing yokes 201, 202 are arranged in the longitudinal direction. The magnetic flux is connected by a plurality of flat magnetic bodies 206 at a predetermined interval toward the plate, and the leakage magnetic flux from the linear motor is reduced by passing most of the leakage magnetic flux through the plate magnetic body 206.

JP 2004-7884 A

JP 2006-54974

Japanese Patent Laid-Open No. 2003-134792

  The linear motor structure shown in Patent Document 1 makes it easy to obtain a relatively high thrust by effectively using the winding space of the coil constituting the mover, but uses a magnetic pole member extending in the thickness direction of the linear motor as an essential member. Therefore, there is a limit to the reduction in thickness, and it has been difficult to realize a linear motor having a thickness of several millimeters.

  The linear motor structure shown in Patent Document 2 is not only difficult to reduce in thickness because it uses an armature core (magnetic pole member) that extends in the thickness direction of the linear motor as in the case of Patent Document 1, but it also has a plate-like yoke. The permanent magnets 112 arranged on both surfaces of the 111 are bonded so that their magnetization directions are opposite to each other via the plate-like yoke 111 (the same magnetic poles face each other), so a large amount of leakage magnetic flux is generated in the surrounding space. There is a problem that will let you. The generation of the leakage magnetic flux not only adversely affects various devices arranged in the vicinity of the linear motor, but is not preferable from the viewpoint of magnetic efficiency, and causes a reduction in thrust. In addition, since the armature core 114 has a commonly connected portion at one end, there is a problem in that interference of magnetic flux of each phase occurs.

  Although the linear motor structure shown in Patent Document 3 can achieve a reduction in leakage magnetic flux by arranging a plurality of flat plate-like magnetic bodies 206, a magnetic body is later applied to the magnetic circuit portion (field pole 204) constituting the linear motor. As a result, there is a possibility that the magnetic flux density in the magnetic gap in which the armature is arranged is changed, and a predetermined thrust may not be obtained.

  The present invention has been made to solve the above-described problems. An object of the present invention is to provide a thin linear motor that realizes a high thrust with little leakage magnetic flux. In particular, the object is to provide a thin linear motor having a thickness of 10 mm or less that is highly versatile and realizes a high thrust.

  In order to achieve the above object, the thin linear motor according to claim 1 is provided with a movable plate that is supported so as to be movable in one axial direction, and a plurality of permanent magnets on one main surface of the movable plate. A pair of magnet arrays arranged in the same direction as the movable plate are arranged to face each other with a predetermined gap in a direction perpendicular to the moving direction of the movable plate, and each permanent magnet is magnetized in the opposing direction of the pair of magnet arrays and the movable plate The direction of the magnetization of the permanent magnets adjacent to each other in the moving direction of the movable magnet row alternately opposite to each other, and the direction of the magnetization of the permanent magnet arranged at the opposite position through the gap, A plurality of electric elements made of a soft magnetic material, which is arranged in a gap formed by the pair of magnet rows and wound with an exciting coil, and having a yoke arranged on the opposite side surface of the opposing surface Core is movable An electric element array that is arranged in the same direction as the rate movement direction and can magnetize an electric core in the direction opposite to the pair of magnet arrays by an exciting current applied to the exciting coil, and a base plate that supports the electric element array It features a thin linear motor composed of a stator having the same.

  The thin linear motor according to claim 2 is the thin linear motor according to claim 1, characterized in that the movable plate is made of a soft magnetic material and the base plate is made of a nonmagnetic material.

In the thin linear motor according to claim 1, the permanent magnets constituting the pair of magnet rows are magnetized in the opposing direction of the pair of magnet rows, and the magnetization directions of the permanent magnets adjacent in the moving direction of the movable plate are alternately Since the direction of magnetization of the permanent magnets that are opposite to each other and opposite to each other through the gap is the same, the direction perpendicular to the moving direction of the movable plate, that is, the direction parallel to the main surface of the movable plate (horizontal direction) Since a yoke is provided on the side surface opposite to the opposing surface of each magnet row, almost no magnetic flux leaks outside the yoke.
Therefore, there is no need to worry about adverse effects on various devices arranged in the vicinity of the linear motor due to magnetic flux leakage, and the degree of freedom of design for incorporation into various devices is increased. There is no need to worry about the adverse effect on the thrust caused by the addition of the magnetic shield member as described in Patent Document 3 described above.

  In addition, a plurality of electric cores made of a soft magnetic material formed by winding an exciting coil are arranged in the same direction as the moving direction of the movable plate, and in the opposite direction of the pair of magnet rows by the exciting current applied to the exciting coil. Since the magnet circuit is arranged so as to be magnetized and the magnetic circuit is closed through the yoke, it is possible to efficiently magnetize the electric core, and the magnet core is arranged in the gap formed by the pair of magnet arrays. Therefore, the linear motor can be thinned.

  Furthermore, since the magnetic flux generated from each permanent magnet is all applied to the electric core due to the arrangement structure of the pair of magnet rows and the electric core, the magnetic flux generated from the permanent magnet is efficiently used for thrust and per magnet weight. The thrust ratio can be increased.

  In the thin linear motor according to claim 2, leakage of magnetic flux to the outside of the linear motor can be further reduced by using the movable plate as a soft magnetic material. That is, due to the magnetization direction of the permanent magnet and the arrangement of the yoke described above, the magnetic flux is generated in a direction parallel to the main surface of the movable plate (horizontal direction) and is not substantially generated in the thickness direction of the linear motor. Even if magnetic flux leaks in the thickness direction of the linear motor, if the movable plate is a soft magnetic material, the movable plate itself functions as a member of the magnetic circuit to prevent leakage of magnetic flux to the outside. Is possible.

  In addition, by using a non-magnetic material for the base plate that supports the electric element array, it is possible to prevent adverse effects on proper magnetic circuit formation.

  According to the present invention, it is possible to provide a thin linear motor with high thrust with less magnetic flux leakage.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 (a) is a front view showing an embodiment of a thin linear motor of the present invention, FIG. 1 (b) is a plan view, FIG. 1 (c) is a side view, and FIG. It is a top view in the state where a movable plate was removed in order to show arrangement relation. The magnet row 4 and the yoke 5 are bonded to the movable plate side.

  In the figure, 1 is a mover and 2 is a stator. The mover 1 has a plate-like movable plate 3 and a plurality of permanent magnets arranged on one main surface of the movable plate 3 arranged in the same direction as the moving direction of the movable plate (direction of arrow XX ′ in the figure). The movable magnet row is composed of a pair of magnet rows 4 and 4 and the yokes 5 and 5 are arranged on the side surface opposite to the opposing surface of each magnet row 4 and 4.

  In the illustrated embodiment, the plate-shaped movable plate 3 is made by cutting pure iron, which is a soft magnetic material, into a predetermined size. The yokes 5 and 5 are also made of pure iron, which is a soft magnetic material, and are arranged at two locations on one main surface of the movable plate 3 such that the longitudinal direction coincides with the moving direction of the movable plate. The yokes 5 and 5 and the movable plate 3 may be composed of independent members. When the pure iron, which is the soft magnetic material, is cut out, the yokes 5 and 5 are formed in a protruding shape so that the movable plate 3 You may comprise integrally with the same member.

  A plurality of block-shaped Nd—Fe—B rare earth sintered magnets are affixed to the insides (opposite surface sides) of the yokes 5 and 5 to form a pair of magnet arrays 4 and 4. The magnetization directions of the permanent magnets are magnetized in a direction opposite to the pair of magnet arrays 4 and 4 as indicated by white arrows in FIG. 2 and the magnetization directions of the permanent magnets adjacent to the moving direction of the movable plate 3 are the same. The permanent magnets are alternately arranged in opposite directions, and are arranged so that the magnetization directions of the permanent magnets arranged at opposite positions via the gap are the same. Therefore, the magnetic flux is generated in a direction perpendicular to the moving direction of the movable plate 3, that is, in a direction parallel to the main surface of the movable plate 3 (horizontal direction).

  Permanent magnets arranged in this thin linear motor are not limited to the Nd-Fe-B rare earth sintered magnets, and well-known permanent magnets such as Sm-Co rare earth sintered magnets and Sr ferrite sintered magnets are employed. However, it is preferable to use the Nd-Fe-B rare earth sintered magnet in order to achieve a small thrust and light weight and high thrust.

  The stator 2 includes a plurality of electric cores 7 made of a soft magnetic material formed by winding the exciting coil 6 shown in FIGS. 3 and 4 arranged in the same direction as the moving direction of the movable plate 3 and the exciting coil. The pair of magnets 4 and 4 can be magnetized by an excitation current applied to 6 in the opposing direction of the pair of magnets 4, and the base plate 9 supports the electron array 8.

  In the illustrated embodiment, the armature core 7 is cut out of pure iron and processed into the shape shown in FIG. 3, and then the excitation coil 6 made of enamel-coated conductor (diameter 0.3 mm) is aligned and wound 50 times in the center. Furthermore, it fixed with the adhesive agent. Next, in order to perform three-phase driving with the electric core 7 around which the exciting coil 6 is wound, three sets of three-phase coils are constructed (referred to as u, v, and w phases, respectively) Seven cases (21 in total) were arranged in the same direction as the movement direction of the movable plate 3.

  More specifically, the electronic element array 8 is fixed with an epoxy resin adhesive at a substantially central part of a base plate 9 made of nonmagnetic material obtained by machining stainless steel (SUS316L), and further, u phase, v phase The w phase was connected in series with each other. In addition, one of the two ends connected in series was a neutral point by connecting the u-phase, v-phase, and w-phase to one point.

  As is apparent from FIG. 2, the arrangement relationship between each of the magnet arrays 4 and 4 and the electric core 7 is two permanent magnets (three lengths for one cycle) (two permanent magnets). A pair of S poles and N poles) are arranged to face each other. Therefore, the magnetic circuit is closed through the yokes 5 and 5 with respect to a set (three pieces) of the cores, and since the magnetic resistance is small, the armature core 7 can be efficiently magnetized.

  Furthermore, by arranging all the arranged cores 7 in series for each phase, the core 7 located directly opposite the permanent magnet has a closed magnetic circuit, so the inductance is large. However, the electric core 7 that does not directly face the permanent magnet has a small inductance because the magnetic circuit is open. For this reason, the applied voltage is almost concentrated on the electric core 7 that is directly opposed to the permanent magnet regardless of the moving position of the mover, and the electric core 7 that is not directly opposed to the permanent magnet consumes little power. High conversion efficiency can be obtained. In particular, since the armature cores 7 are independent without being connected to each other as in Patent Document 2, magnetic flux interference does not occur between the armature cores, and efficient thrust generation can be performed.

  In the above embodiment, the case of three-phase driving has been described, but the effect of the present invention can be exhibited without being limited to this driving method. However, in order to reduce the occurrence of coking thrust and thrust ripple and realize smooth movement, three-phase driving is preferable.

  The electron core 7 is preferably made of a material having a high saturation magnetic flux density from the viewpoint of magnetic efficiency (particularly, the saturation magnetic flux density Bs ≧ 2.0T). In addition to the above pure iron, for example, Fe—Co alloy, Fe—Si alloy, etc. Is preferably used.

  In the thin linear motor of the present invention, as shown in the figure, the length of the electric element array 8 in the moving direction of the movable plate 3 is sufficiently longer than the length of the magnet arrays 4 and 4 (length of the electric element array ≧ magnet array). Length + movable range of movable plate), the magnetic flux generated from the permanent magnet can be used effectively throughout the entire movable range (moving range) of movable plate 3, and the thrust ratio per magnet weight is increased. Can take.

  In the figure, 10 and 10 are linear guides that support the movable plate 3 so as to be movable in a predetermined uniaxial direction, guide rails 11 and 11 fixed on the base plate 9 constituting the stator 2, and the guide rails 11, 11 includes sliding portions 12 and 12 that slide in a predetermined uniaxial direction via 11. The movable plate 3 in which the pair of magnet rows 4 and 4 and the yokes 5 and 5 are arranged on the sliding portions 12 and 12 is attached to a screw or the like while adjusting the gap between the magnet rows 4 and 4 and the electric element row 8. The movable element 1 is configured by fixing the two.

  As described above, the thin linear motor of the present invention is a so-called magnet movable type in which a permanent magnet is arranged on the movable element 1 side, and therefore has a simple configuration without a movable harness, and can be incorporated into various devices and used in daily work. Handling is also easy.

   In the figure, reference numeral 13 denotes an optical linear encoder mounted on the base plate 9 in order to detect the position of the movable plate 3. Reference numeral 14 in the figure denotes a glass linear scale that is bonded and fixed to the movable plate 3, and is disposed at a position facing the optical linear encoder 13. By providing such a position detection device, highly accurate positioning is possible, and the features of the present invention can be realized more effectively.

  In the thin linear motor having the above configuration, when an exciting current is applied to the exciting coil 6, the electric core 7 is magnetized by the exciting current in a direction opposite to the pair of magnets 4 and 4, and is generated in the electric core 7. Due to the interaction between the magnetic flux and the magnetic flux generated from the permanent magnet, a relative thrust acts between the mover 1 and the stator 2, and the movable plate 3 moves in a predetermined uniaxial direction via the linear guide 10. Will be. The moving direction of the movable plate 3 can be switched by switching the direction of the excitation current.

  The present inventor made it possible to provide an ultra-thin linear motor having a width of 55 mm, a length of 90 mm, and a thickness of 7 mm with the structure of the above embodiment. When the dimensions of the movable plate were 55 mm wide and 60 mm long, and the stroke was 20 mm, a high thrust of 10 N or more could be realized. It has become possible to provide a linear motor with a thickness of 10 mm or less, which has been impossible with conventional structures that enable such high thrust.

  FIG. 5 shows the repeat positioning accuracy of the ultra-thin linear motor. This repeated positioning accuracy is obtained by moving the movable plate 3 from the specific position by a predetermined amount, issuing a command to return to the original position, and measuring the displacement (displacement) of the position when returning to the original position. . In Fig. 5, the movement from the first specific position to return to the original position is set as one set, this is repeated, the displacement is measured each time and graphed, the horizontal axis indicates the number of repetitions, the vertical axis Shows the displacement. In the figure, the case where the first specific position is the center position of the base plate 9 and the case where each position is shifted by 10 mm to the left and right are described as the center part and the end part (+10 mm, -10 mm).

  FIG. 5 shows that the positioning accuracy of the ultra-thin linear motor is high.

(A) Front view showing an embodiment of the present invention, (b) Plan view showing an embodiment of the present invention, (c) Side view showing an embodiment of the present invention Partially exploded plan view of FIG. Front view and plan view showing an electric core used in the present invention The top view which shows the electric element row | line | column used by this invention The graph which shows the repeat positioning accuracy of the ultra-thin linear motor which is embodiment of this invention Conventional linear motor Other conventional linear motors

Explanation of symbols

1 Mover
2 Stator
3 Movable plate
4 Magnet row
5 York
6 Excitation coil
7 Electron coil
8 Electron train
9 Base plate
10 Linear guide
11 Guide rail
12 Sliding part
13 Optical linear encoder
14 Linear scale
111 Plate-shaped yoke
112 Permanent magnet
113 Stator
114 Armature core
115 Armature coil
116 Mover
201, 202 York
203 Permanent magnet
204 Field pole
206 Magnetic material

Claims (2)

A movable plate supported so as to be movable in one axial direction, and a pair of magnet arrays formed by arranging a plurality of permanent magnets on one main surface of the movable plate in the same direction as the moving direction of the movable plate are perpendicular to the moving direction of the movable plate. Forming a predetermined gap in the direction and facing each other, each permanent magnet is magnetized in the direction opposite to the pair of magnet rows, and the magnetization directions of the permanent magnets adjacent to the moving direction of the movable plate are alternately reversed, and A movable element having a movable magnet array in which the directions of magnetization of the permanent magnets arranged at opposing positions through the gap are the same, and a yoke arranged on the side surface opposite to the opposing surface of each magnet array; Arranged in the gap formed by the magnet array, a plurality of cores made of a soft magnetic material formed by winding an exciting coil are arranged in the same direction as the moving plate and applied to the exciting coil. Thin linear motor comprising a stator having a armature core by the excitation current and the magnetizable electric element row to the pair of magnet rows opposite direction, a base plate for supporting the electrical terminal sequence that. 2. The thin linear motor according to claim 1, wherein the movable plate is made of a soft magnetic material and the base plate is made of a nonmagnetic material.

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