JPH03164057A - Linear motor - Google Patents

Abstract

PURPOSE:To provide a large thrust, a long stroke by disposing magnets having different polarities at both sides of coil assemblies along the moving route of the assemblies, and further disposing magnetic units at the advancing side face of the assemblies. CONSTITUTION:First and second magnets 18A, 20A having different polarities are disposed along the moving route of coil assemblies 4, 6 moving at center poles 8, 10 on a lower board 12A. Third and fourth magnets 18B, 20B are similarly arranged on the lower surface of an upper board 12B. Further, magnetic units 50, 52 are disposed on the advancing side faces of the assemblies 4, 6. Thus, magnetic circuits M1, M2 for forming a magnetic circuit are formed perpendicularly to the advancing direction of the assemblies 4, 6. Thus, magnetic fluxes flowing to the board and the pole are only magnetic flux generated perpendicularly to the member, a large thrust and a long stroke can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) The present invention generally relates to a voice coil type linear motor, and particularly relates to a linear motor capable of realizing large thrust and long stroke.

Traditionally, voice coil type linear motors have been widely used in various fields, such as as a magnetic head drive device for magnetic disk drives, or as a table drive device for laser processing machines and semiconductor manufacturing machines. .

In general, voice coil type linear motors have the disadvantage that the larger the thrust and longer the stroke, the larger the device becomes due to the problem of magnetic saturation of the iron core (yoke).

That is, as shown in FIGS. 7 and 8, the conventional voice coil type linear motor has a movable plate 2 to which, for example, a magnetic head of a magnetic disk device is attached, and a lower surface of the movable plate 2. A coil assembly 4 is fixed to the coil assembly 4. The coil assembly 4 includes a center ball 8 made of magnetic material.
is arranged so that the coil assembly 4, that is, the movable plate 2, is slidable relative to the center ball 8.

A lower yoke, that is, a substrate 1 facing the center ball 8
2 is arranged, and the substrate l2 and the center ball 8 are integrated with a spacer 14 interposed therebetween.

A magnet 18 is arranged on the substrate l2 along the moving path of the coil assembly 4.

As described above, in the conventional linear motor, the traveling direction of the coil and the flowing direction of the magnetic flux coincide, so it is very difficult to achieve both a long stroke and a large thrust at the same time. In other words, to achieve a large thrust, the gap magnetic flux density between the coil and the magnet must be relatively large.
This means increasing the amount of flux (magnetic flux) generated from the magnet per unit length in the traveling direction.

Therefore, in order to achieve a long stroke at this time, the magnet must be extended long in the direction of travel, and the total amount of flux generated from the magnet becomes enormous, and the cross-sectional area of the lower yoke becomes large due to magnetic saturation. No choice but was. This results in an increase in the size of the linear motor, resulting in inconveniences such as the inability to mold large magnets, such as rare earth magnets, and it is virtually impossible to manufacture them.

For this reason, even in voice coil type linear motors that are currently widely used and are said to have a large thrust and a long stroke, the thrust is 20 N and the stroke is 100 mm.

In recent years, there has been a demand for voice coil type linear motors that can achieve larger thrust and stroke, such as a thrust of 300 N and a stroke of 600 mm. For this purpose, a large number of magnets are placed in a row along the moving coil so that adjacent poles are different, that is, alternately with north poles and
A multi-pole type glue near motor arranged so as to form the S pole has been proposed and put into practical use.

However, in such a multi-pole type glue motor, the magnets with north and south poles are arranged alternately in one row, so a magnetic attraction force acts on the moving coil side, causing the moving side to This affected the bearings, etc., and significantly shortened the life of the equipment. Furthermore, it is necessary to change the flow of current to the moving coil as the magnetic poles of the magnet change, and a switching circuit such as a Hall element is required to excite the coil, which increases the cost of the device. It also had the problem of large thrust fluctuations.

Therefore, the object of the present invention is to eliminate the influence of unnecessary 6B air suction force, extend the life of the device, and achieve large thrust and long stroke without causing fluctuations in thrust, at a low cost, and The purpose is to provide a small glue near moyu.

The above-mentioned objective for achieving the above is fully achieved in the linear mode according to the present invention. In summary, the present invention includes first and second center balls arranged in parallel, first and second coil assemblies slidably provided on the first and second center balls, respectively, and the first and second center balls arranged in parallel. a magnetic body fixed to at least one side surface of the first and second coil assemblies between the first and second center balls; a movable plate to which the first and second coil assemblies are attached; First and second magnets are disposed on one side of the first and second coil assemblies, respectively, and have different polarities along the movement path of the first and second coil assemblies; The first and second coil assemblies are disposed on the other measurement section of the first and second coil assemblies along the moving path of the first and second coil assemblies so as to face the first and second magnets. 1st and 2nd
third and fourth magnets having the same polarity as the magnet; a substrate made of a magnetic material to which the first and second magnets are attached; and a substrate made of a magnetic material to which the third and fourth magnets are attached. The present invention is a near moderator characterized in that it is equipped with a printed circuit board. Preferably, each of the first, second, third, and fourth magnets is configured by arranging a plurality of magnets at predetermined intervals.

Practical 1L Example Next, the linear motor according to the present invention will be explained in more detail with reference to the drawings.

1 to 4 show an embodiment of a linear motor according to the present invention. According to this embodiment, the linear motor 1 has first and second center balls 8 and 10 made of magnetic material and arranged in parallel. First and second coil assemblies 4, 6 are provided in a loose fit. A coil head, that is, a movable plate 2, to which a movable table of a laser processing machine, a semiconductor manufacturing machine, etc., for example, is attached, is fixed to the first and second coil assemblies 4 and 6 on the left and right outer side surfaces in FIG. be done. 1st
and the second two coil assemblies 4, 6 may have the same shape and dimensions.

According to this embodiment, each coil assembly 4, 6 has a coil winding of rectangular cross section, as will be explained in more detail later, so that a center ball 8 passing through the coil assembly , lO also have a rectangular cross section. Preferably,
A steel pipe is fitted around the center ball.

The linear motor 1 also includes a magnetic material on both vertical side surfaces of the first and second coil assemblies in this embodiment along the movement paths of the coil assemblies 4 and 6 along the center balls 8 and 10. The formed rectangular lower substrate (lower yoke) 12
A and an upper substrate (earth yoke) 12B are arranged. Both substrates 12A,]. 2B are fixed together with a spacer 14 via center balls 8 and 10, as seen in FIG. The baser 14 may be made of a magnetic material, or may be made of a non-magnetic material such as stainless steel (SUS304). Also, the first and second center balls 8, 10 have both ends covered with magnetic material 16.
Children can connect with each other.

According to the present invention, on the lower substrate 12A, along the moving path of the coil assemblies 4, 6 that move opposite to the first and second center balls 8, 10, that is, along each center ball, first and second magnets 18 A, respectively;
2OA is placed. At this time, the first magnet disposed along the moving path of the first coil assembly 4]. 8
The polarities of A and the second magnet 2OA disposed along the movement path of the second coil assembly 6 are made to be different from each other. In this embodiment, the first magnet 18A has an S pole, and the second magnet 2OA has an N pole.

Further, on the lower surface of the upper substrate 12B, along the movement path of the coil assemblies 4, 6 that move along the respective center balls, facing the first and second center balls 8, 1O,
Third and fourth magnets 18B and 20B are arranged, respectively. At this time, the third magnet 18B disposed along the moving path of the first coil assembly 4 has the same polarity as the first magnet 18A disposed opposite to it, and
A fourth coil assembly disposed along the movement path of the second coil assembly 6.
The magnet 20B has the same polarity as the second magnet 2OA disposed opposite to it.

First, second, third and fourth magnets 18A, 2OA,
18B and 20B may consist of a single magnet extending along the travel path of each coil assembly, as illustrated in FIG. 1, or as illustrated in FIG. , the first and third magnets 18A, 18B have a width a,
It is constructed by arranging a plurality of magnets 18a to 18h having a length β at equal intervals at a distance b, and the second and fourth magnets 2OA and 20B also have a width a and a length a. A plurality of magnets 20a to 20h are connected at a distance b.
It can also be constructed by arranging them at equal intervals. At this time, the first magnet 18A and the second magnet 2OA are arranged so that the third magnet 18B and the fourth magnet 20B are out of phase with each other by b/2 along the arrangement direction, and the first and second magnets The winding length C of the two-coil assemblies 4 and 6 (that is, the coil width in the magnet arrangement direction) is m (a
+b) (m is an integer).

Moreover, each magnet 18A, 20A. 18B and 20B are provided over an appropriate length dimension depending on the required stroke amount of the first and second coil assemblies 4 and 6, that is, the movable table 2.

Furthermore, according to the present invention, as shown in detail in FIGS. 5 and 6, there is a groove between the center balls 8 and 10 of the first and second coil assemblies 4 and 6 and on the side surfaces in the traveling direction. , magnetic bodies 50 and 52 are arranged, respectively. In some cases,
It is also possible to provide the magnetic material only on one side surface.

According to the linear motor 1 of the present invention constructed as described above, the magnetic circuit, as understood from FIGS. 4 and 6, includes the first magnet 18A→substrate 12A−second magnet 20A−second magnet Center ball 10 → magnetic material 50, 52
1. First center ball 8 -> magnetic circuit M1 consisting of first magnet 18A, third magnet 18B - board 12B
→Fourth magnet 20B→Second center ball 10→Magnetic bodies 50, 52→First center ball 8→A magnetic circuit Ma consisting of third magnet 18B is formed, and each magnetic circuit has movable first and second The coil assemblies 4 and 6 are formed substantially perpendicular to the traveling direction thereof. Of course, the directions of the currents i flowing through the first and second coil assemblies 4 and 6 are different from each other.

As described above, it will be understood that the linear motor 1 of the present invention is significantly different from the conventional linear motor in which the magnetic circuit is formed along the direction of movement of the coil assembly in the manner in which the magnetic circuit M is formed. In other words, in conventional linear motors, when the stroke of the movable coil, that is, the movable table, is increased, the flux flowing to the substrate and center ball inevitably becomes large, causing the problem of magnetic saturation, and causing the problem of magnetic saturation. The ball needed to be huge. In contrast, in the nonia moder of the present invention, even if the stroke is made larger and the length or number of magnets is increased, the flux flowing to the board and center ball is equal to the flux of all the magnets provided on the board. Instead, it is simply a f that occurs orthogonally to such a member. This prevents the substrate and center ball from becoming huge due to magnetic saturation as in the conventional case.

Further, according to the present invention, even when a large thrust force is required, it can be achieved simply by designing the ampere-turns of the coils of the first and second coil assemblies to the required value. Further, according to the present invention, unlike conventional high-thrust linear motors, increasing the ampere turn of the coil does not have any effect on the magnet, which is also a great advantage. That is, according to the present invention, the gap magnetic flux density between the center ball and the magnets is 18 (A.B) and 20 (A.B).
This results in the result that the influence of increasing the ampere turns of the coil is alleviated.

Further, according to the configuration of the present invention, the first, second, third and fourth
The magnet can be composed of multiple magnets, and has the advantage that it can be used later when it is difficult to form large magnets such as rare earth magnets. Even when used as a magnet, as described above, it has the advantage that thrust fluctuations can be suitably suppressed by appropriately selecting the arrangement of each magnet and the coil width.

In addition, in particular, in the magnetic circuits M , , M z , the flux F flowing from the second center ball 10 to the first center ball 8 causes the coils in adjacent portions of the first coil assembly 4 and the coil 6 of the second assembly to If the flow crosses the movable table 2, it will generate a thrust that obstructs the original thrust for the movable table 2. However, according to the present invention, as described above, the , second coil assembly 4
, 6, the flux F flowing from the second center ball 10 to the first center ball 8 does not cross the coils in adjacent portions of the coils of the first coil assembly and the second assembly. The above problem is solved by bypassing the flux F.

Therefore, the magnetic bodies 50 and 52
It has a size sufficient to allow the flux flowing from the center ball 8 to the first center ball 8 to pass therethrough without any resistance.

According to the present invention, the thrust is 300N or more and the stroke is 600N.
It is possible to easily manufacture a small glue near motor with performance of 1 mm or more.

4.11 As described above, in the linear motor according to the present invention, the coil assemblies are slidably provided on the two center balls arranged in parallel, and the polarities of the coil assemblies differ from each other along the movement path of the coil assemblies. Because the structure is such that magnets are arranged opposite to each other on both sides of each coil assembly, and a magnetic body is arranged on the side of each coil assembly in the traveling direction,
It eliminates the effects of unnecessary magnetic attraction, extends the life of the device, achieves large thrust and long stroke without causing any fluctuation in thrust, and has the advantages of being low-cost and compact. have

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along the line 1-1 in the second diagram of an embodiment of the linear motor according to the present invention, FIG. 2 is a central vertical sectional view, and FIG.
The figure is a plan view showing the structure of the magnet with the movable plate removed, Figure 4 is an enlarged sectional view taken along line IV-IV in Figure 1, Figure 5 is a perspective view of the coil bobbin, and Figure 6 is the flux diagram. A sectional view explaining the flow, FIG. 7 is a plan view of a conventional linear motor, and FIG. 8 is a front view. 2: Movable plates 4, 6: First and second coil assemblies 8, 10: First and second center balls 12A, 12B: Substrate 18A: First magnet 18B: Third magnet 20A: Second magnet 2 O B : 4th magnet 50, 52: Magnetic body 1 Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6

Claims (1)

[Claims] 1) first and second center balls arranged in parallel;
first and second coil assemblies slidably provided on the first and second center balls, respectively, and at least one of the first and second coil assemblies between the first and second center balls; A magnetic body fixed to one side part,
a movable plate to which the first and second coil assemblies are attached; and a movable plate disposed on one side of the first and second coil assemblies, respectively, along a movement path of the first and second coil assemblies. , first and second magnets having different polarities, and the first and second magnets facing the first and second magnets along the moving path of the first and second coil assemblies. third and fourth magnets arranged on the other side of the two-coil assembly and having the same polarity as the opposing first and second magnets; and formed of a magnetic material to attach the first and second magnets. A linear motor comprising: a magnetic substrate; and a substrate made of a magnetic material to which the third and fourth magnets are attached.