JPH01286763A - Dc linear motor - Google Patents

Abstract

PURPOSE:To reduce in cost and size a DC linear motor by connecting center yokes to each other at their ends, providing a yoke at its outside, and short- circuiting thereby between poles. CONSTITUTION:An integral moving body 32 is composed of center yokes 11, 21 disposed in parallel, and coils 12, 22 wound at a predetermined interval around the yokes. Permanent magnets 13A, 13B disposed at opposite positions at a predetermined interval on the outer periphery of the coil 12, permanent magnets 23A, 23B disposed similarly to the magnets 13A, 13B, and outer thin plate yokes 24A, 24B are provided to construct a DC linear motor. S-, N-poles of the yokes 24A, 24B are short-circuited by the combinations of the respective two magnets 13A, 23A and 12B, 23B, and operated as the neutral point of a magnetic field. The magnetic field is introduced from the N-poles of the magnets 13A, 13B through the coil 12 to the yoke 11, and introduced from the end of the yoke 11 through the coil 22 and the like to the magnets 23A, 23B.

Description

[Detailed Description of the Invention] Field of Application in Ea Industry] The present invention relates to a DC linear motor, and more specifically, it is used for driving heads in devices such as magnetic disks and optical disks, or for driving heads and media in magnetic cards and optical card devices. This invention relates to a voice coil type OC linear motor suitable for performing linear motion.

[Prior Art] When trying to obtain linear motion by driving a rotary motor, which is commonly used in industrial equipment, various motion conversion mechanisms are required to convert rotational motion into linear motion. The presence of such a converter makes it difficult to obtain highly accurate positioning and high-speed response, and the structure becomes complicated, which impedes miniaturization. On the other hand, linear motor mechanisms provide direct linear motion using the motor itself, eliminating the need for a motion conversion mechanism, making it possible to simplify and downsize the motor structure, as well as improve precision when combined with electrical control. Because they exhibit high positioning and high-speed response, their use in recent years has rapidly increased in application fields that were previously impossible with rotary motors.

By the way, there are various types of linear motors, but voice coil type DC linear motors (hereinafter referred to as VCM) have a relatively similar structure, and the main movable part that generates thrust is a coil, so it is difficult to load. It has the great advantages of being lightweight and providing high-speed response. But on the other hand,
In principle, with vClll, the permanent magnet surface facing the coil is either N or S pole, and the magnetic path is closed outside the coil movable part to create a loop, so if the stroke is long, Due to the saturation magnetic flux density, the cross-sectional area of the yoke becomes large, resulting in an increase in the overall size of the structure.

Figures 3^ and 3B show an example of the configuration of a conventional VCM, with Figure 3A being a cross section, and Figure 38 being a cross section of the
A cross section taken along the ^-A line in the figure is shown.

In these figures, 1 is a center yoke, and 2 is a coil provided around the center yoke 1 at a predetermined interval.
In the figure, it is held so that it can be moved left and right. 3^ and 3B are permanent magnets that maintain a predetermined distance from the outside of the coil 2 and are arranged in the same direction as the center yoke l, so that their same poles face the outside of the coil 2, that is, in this example. In the case of , the N pole is provided so as to face the outside of the coil 2, and is held by outer yokes, 4^ and 4B, provided along each of these permanent magnets Go^ and 3B.

Reference numeral 5^ denotes an auxiliary yoke that connects the respective ends of the center yoke 1 and the outer yoke 4A, and 5B represents an auxiliary yoke that connects the respective ends of the center yoke 1 and the outer yoke 4B. Therefore, in the VCM configured in this way, the magnetic flux generated from each of the magnets 3^ and 3B flows toward the center yoke 1 as shown by the arrows, and the magnetic fluxes from the magnets 3^ and 3B flow toward the center yoke 1 and the auxiliary yokes 5^ and 5.
B, are led to outer yokes 4^ and 4B, and return to permanent magnets 3^ and 3B, respectively. Therefore, approximately 1/2 of the total magnetic flux passing through the gaps 68 and 6B between the permanent magnets 3^ and 3B and the center yoke 1 flows toward the right end of the center yoke 1, and flows toward the right end of the center yoke 1, and the auxiliary yokes 5^ and 5B
and approximately one-half more flows to each outer yoke 4^ and 48. That is, the total magnetic flux is about 172 at the right end cross-section B-B of the center yoke 1, and the total magnetic flux is about ! /4 will flow in each, and if the yokes are used within the saturation magnetic flux density, the cross-sectional areas of the outer yokes 4^ and 4B are required to be approximately 172 times the cross-sectional area of the center yoke 1 if they are made of the same material. be done.

In addition, as another conventional example, as shown in FIGS. 4A and 4B, there is a structure in which the outer yoke 4 is integrally constructed to increase the cross-sectional area. Other than that, it is basically the same as the conventional example described above.

[Problems to be Solved by the Invention] However, as mentioned above, in the conventional VCM, the size and total weight of the two outer yokes are almost the same as the center yoke, and in order to lengthen the driving range of the coil, that is, the stroke. If you lengthen the magnet, ! l! At the same time as the number of magnetic fluxes increases and the cross-sectional area of the center yoke increases, the two outer yokes also become thicker in proportion to the increase, and the cross-sectional area of the auxiliary yoke also increases.

As a practical example, in a VCM with an air gap magnetic flux density of 2000 Gauss, a stroke of 80 mm, and a magnet width of 35 m, the total weight of the two outer yokes and the auxiliary yoke is approximately 17 of the total am.
2, which has the disadvantage that the ratio of these components to the overall height becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a DC linear motor which can eliminate the above-mentioned conventional drawbacks and which can reduce the overall height and weight.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a plurality of center yokes arranged in parallel and having one ends connected to each other,
A plurality of coils are loosely fitted around each of the plurality of center yokes at a predetermined interval so as to be freely movable, and a plurality of coils configured on the moving body of the body, and a plurality of coils arranged at a predetermined interval along the direction of movement on both sides of the moving body. a plurality of pairs of permanent magnets arranged parallel to the center yoke and spaced apart from each other, and a plurality of permanent magnets provided on the same side of the plurality of pairs of permanent magnets. a plurality of permanent magnets provided on the same side, each having a plurality of outer yokes disposed on the same side, the poles of the surfaces facing the coils of the plurality of permanent magnets provided on the same side being different from each other between adjacent comrades; The poles of the outer yoke are short-circuited by each of the outer yokes.

[Function] According to the present invention, a plurality of pairs of permanent magnets are arranged on both sides of a plurality of coils configured in an integral moving body, in parallel with the center yoke, at a predetermined distance from each coil, and spaced apart from each other. However, on the same side facing the coil, different poles are formed between adjacent magnets, and by providing a yoke further outside these permanent magnets, the outer yoke A neutral point between adjacent permanent magnets can be obtained, the thickness of the outer yoke can be reduced, and the overall structure can be made thinner and lighter.

[Examples] Examples of the present invention will be described below in detail and specifically based on the drawings.

1A to 1C show an embodiment of the present invention. In these figures, 11 and 21 are center yokes arranged in parallel, and 12 and 22 are predetermined holes around the center yokes 11 and 21, respectively. The coils are wound with a gap maintained between them, and the coil 12 and the coil 22 are the 13th coil.
As shown in the figure, the center yokes 11 and 21 are fixed back to back to each other, and are configured as an integral moving body 32.

Permanent magnets 13^ and 1311 are respectively arranged at opposing positions with a predetermined spacing from the outer periphery of the coil 12, and in this example, the opposing surfaces of the permanent magnets 13^ and 13B are arranged as north poles. It's Nishide.

Further, 23A and 23B are permanent magnets that are similarly placed at a position facing the outer periphery of the coil 22 at a predetermined distance. This is how it should be. 24^ is permanent magnet 1
24B is an outer thin plate yoke holding permanent magnets 1311 and 23B, while center yokes 11 and 21 have their ends joined to each other as shown in FIG. 1C. The outer thin plate yokes 24^ and 24B are fixed to the ends thereof.

In the DC linear motor configured in this way, the outer thin plate yokes 24 and 24B are each connected to two magnets.
The combination of and 23^ and 13B and 238 short-circuits the south pole and north pole to each other and acts as a neutral point of the magnetic field, and the magnetic flux flows from the north pole of magnets 13^ and 13B to the center yoke via the coil 12. ! The center yoke 21 is guided by the summer and soaked in the center yoke 21 from its end.
From there, it passes through the coil 22 and is guided to the magnets 23^ and 23B. Thus, the bulk of the magnetic flux in the thin plate yokes 24 and 24B is directed in the direction shown by arrow M in FIG. It becomes a flow. Therefore, the plate thicknesses of the thin plate yokes 248 and 24B can be reduced based on the distribution state of the saturation magnetic flux density in the thin plate yokes 248 and 24B.

According to the inventor's estimate, the distance of the moving body 32 is 200.
In the case of a conventional VCM, each of the outer yokes 4^ and 4B would require a thickness of approximately lesm, whereas in the case of the structure of the above embodiment, the thin plate yoke 24 It is possible to make each of ^ and 24B as thin as about 2 ms.

Further, the thick auxiliary yokes 5^ and 5B as shown in the conventional example are not required, and the ends of the thin plate yokes 24^ and 24B are simply bent and fixed for connection as shown in Fig. 1A. Only B is sufficient for both weight and structure.

FIG. 2 shows another embodiment of the present invention. In this example, only the upper part of the VCM is shown for the sake of clarity. In this example, two coils 12 and 22 are attached to a coil holding frame. It is sandwiched between 33 and 34 to form an integral moving body 42. Note that the other configurations follow the previously described embodiment.

As mentioned above, permanent magnets 13^, 23^.

13B and 23B have the same total volume as before,
Although it is made of inexpensive materials such as ferrite.

If further miniaturization is required, rare earth metals, zirconia, or the like may be used.

Further, in the embodiment described above, two coils are arranged in parallel, but the number of coils is not limited to this, and may be three, for example. However, in such a case, it goes without saying that it is necessary to construct the outer thin plate yoke so that the total number of magnetic fluxes between its NS poles is the same and the neutral point of the magnetic field is maintained.

Further, the coils may be electrically connected in series or in parallel, and by making the directions of current flowing through each coil opposite to each other, thrust in the same direction can be obtained.

[Effects of the Invention] As explained above, according to the present invention, a plurality of conventional motors in which the pole faces of the magnets facing the coils are adjacent to each other and different from each other are arranged in parallel, and the plurality of coils are connected to each other at their ends, and a yoke is provided on the outside of adjacent magnets, and these outsides are connected to each other at their ends. Since the magnetic poles are short-circuited by the yoke, the following effects can be obtained.

(1) Individual magnets are miniaturized, and the mold for the magnet is small, which contributes to cost reduction, especially in the case of special production in small numbers.

(2) The outer yoke can be manufactured by sheet metal processing using a thin plate, and costs can be reduced by using parts of the same shape.

(3) The overall weight and shape can be reduced, and a C linear motor can be provided which is suitable for use in an information recording and reproducing device that drives a carriage to record and reproduce information.

[Brief explanation of the drawing]

Figure 1^ is a cross-sectional view showing an example of the configuration of the DC linear motor of the present invention, Figure 1B is a cross-sectional view taken along the line C--C of Figure 1A, and Figure 1C is a cross-sectional view of the DC linear motor of the present invention.
Figure A is a top view, Figure 2 is a perspective view of the upper half of another embodiment of the present invention, Figure 3A is a sectional view of an example of the configuration of a conventional DC linear motor, and Figure 3B is Figure 3A. A cross-sectional view taken along line ^-8 in the figure, FIG. 48, and FIG. 4B are a perspective view and a front view of another conventional example. 11.21... Center yoke, 12.22-... Coil, 13^, 13B, 23^, 23B -... Permanent magnet, 2
4^, 24B...outer thin plate yoke, 32.42...
Motion body, 33J4-... Coil holding frame. One pod of the light of the light shows the 1 beggar. Figure 3A showing the advantage to cedar 1 Figure 3A/) 1st person 1zub village f
7 Fig. 4A/Taryok 1/Taryok gravel Fig. 4A/) Five faces Fig. 48

Claims (1)

[Scope of Claims] A plurality of center yokes arranged in parallel and connected to each other at one end, and an integrated moving body that is loosely fitted around each of the plurality of center yokes with a predetermined gap therebetween so as to be movable. a plurality of pairs of permanent magnets arranged on both sides of the moving body at predetermined intervals along the moving direction and parallel to the center yoke and spaced apart from each other; , an outer yoke provided on the outside of each of the plurality of permanent magnets provided on the same side of the plurality of pairs of permanent magnets, the plurality of permanent magnets provided on the same side; The poles of the surfaces facing the coils are different between adjacent comrades, and the poles of the plurality of permanent magnets provided on the same side are short-circuited by each of the outer yokes. DC linear motor.