WO2014167720A1 - Movable element and linear motor - Google Patents

Abstract

A movable element according to the present invention comprises: a shaft (11) having a rod shape extending in a first direction; and a plurality of magnets (12, 13) having a cylindrical shape through which the shaft (11) is inserted, the plurality of magnets (12, 13) having thrust magnets (12) generating magnetic flux parallel to a first direction and radial magnets (13) generating magnetic flux in the radial direction of the cylindrical shape. The thrust magnets (12) and the radial magnets (13) are alternately arranged side by side so that the thrust magnets (12) are arranged at both ends. Fixing members (14) made of a magnetic material are further provided adjacently further outward along the first direction with respect to each thrust magnet (12) arranged at both ends.

Description

Mover and linear motor

The present invention relates to a mover and a linear motor.

Conventionally, a linear motor in which the mover performs a linear operation has been used. As such a linear motor, there is a shaft type linear motor in which a shaft penetrating through a through hole formed in a stator operates as a mover.

A shaft that functions as a mover in a shaft type linear motor may have a plurality of cylindrical magnets attached thereto. For example, a magnet attached to a shaft includes a magnet that generates a magnetic flux in a direction parallel to the extending direction of the shaft (hereinafter also simply referred to as a thrust magnet), and a magnet that generates a magnetic flux in a cylindrical radial direction (hereinafter simply referred to as a magnet). (Also referred to as a radial magnet). For example, as disclosed in Patent Document 1, the magnets may be arranged in a so-called Halbach arrangement in which thrust magnets and radial magnets are alternately arranged.

JP 2011-147333 A

However, according to the conventional technique, among the magnets arranged in the Halbach arrangement, the path of the magnetic flux generated from the magnet arranged at the end is different from the path of the magnetic flux generated from the magnet arranged at the center. As a result, leakage magnetic flux is likely to be generated. And there existed a problem that the thrust characteristic of a linear motor may deteriorate by generation | occurrence | production of leakage magnetic flux.

The present invention has been made in view of the above, and an object of the present invention is to obtain a mover that can suppress leakage magnetic flux from magnets arranged in a Halbach array and improve the thrust characteristics of a linear motor. To do.

In order to solve the above-described problems and achieve the object, the present invention includes a shaft that has a rod-like shape extending in a first direction, and a plurality of magnets that have a cylindrical shape and through which the shaft passes. The plurality of magnets includes a thrust magnet that generates a magnetic flux parallel to the first direction and a radial magnet that generates a magnetic flux in the radial direction of the cylindrical shape, and the thrust magnets are disposed at both ends. In this way, the thrust magnets and the radial magnets are arranged alternately and are made of a magnetic body arranged adjacent to the outer side along the first direction with respect to the respective thrust magnets arranged at both ends. It further has a fixing part.

The movable element according to the present invention has an effect that it is possible to obtain a movable element capable of improving the thrust characteristics of the linear motor by suppressing generation of leakage magnetic flux.

FIG. 1 is a cross-sectional view showing a schematic configuration of a linear motor according to Embodiment 1 of the present invention. FIG. 2 is a diagram illustrating a manufacturing procedure of the mover. FIG. 3 is a diagram illustrating a manufacturing procedure of the mover. FIG. 4 is a diagram illustrating a manufacturing procedure of the mover. FIG. 5 is a diagram illustrating a manufacturing procedure of the mover. FIG. 6 is a diagram for explaining the magnetic flux generated from the magnet included in the mover in the linear motor according to the first embodiment. FIG. 7 is a diagram for describing magnetic flux generated from a magnet included in a mover in a linear motor shown as a comparative example.

Hereinafter, a mover and a linear motor according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a schematic configuration of a linear motor according to Embodiment 1 of the present invention. The linear motor 50 is a linear motor in which the shaft 11 pierced through the through hole 1a formed in the casing 1 operates linearly along the direction indicated by the arrow Z (first direction). That is, the linear motor 50 is a shaft type linear motor in which the shaft 11 side functions as a mover and the casing 1 side functions as a stator.

A space capable of accommodating the shaft 11 is formed inside the casing 1. The casing 1 is formed with a through hole 1a that penetrates both ends of the shaft 11 accommodated therein. A linear bush 4 that holds the shaft 11 movably along the direction indicated by the arrow Z is attached to the through hole 1a.

Inside the casing 1, a coil 2 and a yoke 3 are provided. The coil 2 is provided inside the casing 1 so as to surround the periphery of the shaft 11. The yoke 3 is provided outside the coil 2 inside the casing 1. The stator of the linear motor 50 is configured including the casing 1, the coil 2, the yoke 3, and the linear bush 4 described above.

The mover of the linear motor 50 includes a shaft 11, magnets 12 and 13, and a retaining ring (snap ring, fixed portion) 14. 2 to 4 are diagrams showing a procedure for manufacturing the mover. Hereinafter, the description of the manufacturing procedure of the mover will be made including the detailed configuration of the mover.

As shown in FIG. 2, the shaft 11 has a rod-like shape extending in the direction indicated by the arrow Z. The shaft 11 is formed with two grooves 11a extending along the circumferential direction. As shown in FIG. 3, the retaining ring 14 is fitted into one of the two grooves 11a. The retaining ring 14 is made of a magnetic material such as iron.

A plurality of magnets 12 and 13 having a cylindrical shape are attached to the shaft 11. More specifically, the shaft 11 is passed inside the plurality of magnets 12 and 13 having a cylindrical shape. The magnets 12 and 13 that are initially attached to the shaft 11 are pressed against a retaining ring 14 that has been previously fitted into one groove 11a. Further, the plurality of magnets 12 and 13 are disposed adjacent to each other between the two grooves 11a.

The magnets 12 and 13 attached to the shaft 11 include a thrust magnet 12 in which the direction of the generated magnetic flux is parallel to the direction in which the shaft 11 extends, and a radial magnet 13 in which the direction of the generated magnetic flux is the radial direction of the shaft 11. Is done.

The first magnet and the last magnet attached to the shaft 11 are the thrust magnets 12. Further, the thrust magnets 12 and the radial magnets 13 are alternately arranged. That is, the magnets 12 and 13 are attached to the shaft 11 in a Halbach array in which both ends are thrust magnets 12.

When all the magnets 12 and 13 are attached to the shaft 11 as shown in FIG. 4, the retaining ring 14 is fitted into the other groove 11a as shown in FIG. The inner peripheral surfaces of the magnets 12 and 13 and the outer peripheral surface of the shaft 11 are bonded by an adhesive or the like. Thereby, the magnets 12 and 13 are fixed to the shaft 11.

Referring back to FIG. 1, one retaining ring 14 is disposed so that the thrust magnet 12 provided at the end is in close contact therewith. A gap is provided between the other retaining ring 14 and the thrust magnet 12. The clearance between the other retaining ring 14 and the thrust magnet 12 is filled with a hardened portion 15. The curing unit 15 is, for example, an adhesive, and is fixed between the retaining rings 14 by being cured after being filled with a gap. The curing unit 15 is not limited to an adhesive, and any curing unit 15 may be used as long as it is cured after filling the gap.

The region where at least the magnets 12 and 13 are arranged in the movable part is accommodated in the casing 1. In the casing 1, the magnets 12 and 13 of the mover and the coil 2 of the stator are opposed to each other. Then, by controlling the current flowing through the coil 2, the mover can be moved in the direction indicated by the arrow Z.

FIG. 6 is a diagram for explaining the magnetic flux generated from the magnet included in the mover in the linear motor 50 according to the first embodiment. In the linear motor 50, among the magnets 12 and 13 arranged on the shaft 11, adjacent to the outer side along the extending direction of the shaft 11 with respect to the thrust magnets 12 arranged at both ends. A retaining ring 14 made of a magnetic material is provided.

By providing the retaining ring 14 outside the thrust magnet 12 at the end, the magnetic flux generated from the thrust magnet 12 at the end passes through the outer peripheral surface of the retaining ring 14 that is a magnetic body. Thus, the magnetic flux generated from the thrust magnet 12 at the end passes through the same path as that in which a radial magnet is further provided outside the thrust magnet 12. In other words, the magnetic flux generated from the thrust magnet 12 at the end passes through the same path as the radial magnet 13 provided on both sides of the thrust magnet 12.

Therefore, the magnetic flux paths X1 and X5 generated on the end side and the magnetic flux paths X2 to X4 generated in other portions, that is, the portions where the radial magnets 13 are provided on both sides of the thrust magnet 12 are provided. It is possible to make the distance that the air passes through the air uniform. As a result, the magnetic resistances of the paths X1 to X5 of the magnetic flux generated from the magnets 12 and 13 of the mover can be made uniform, and the amount of magnetic flux passing through the paths X1 to X5 can be made uniform.

FIG. 7 is a diagram for explaining the magnetic flux generated from the magnets 12 and 13 included in the mover in the linear motor 100 shown as the comparative example. In the linear motor 100 shown as a comparative example, no magnetic body is provided on both sides of the magnets 12 and 13 arranged on the shaft 11.

Therefore, the paths Y1 and Y5 of the magnetic flux generated from the thrust magnet 12 at the end are portions that pass through the air as compared to the paths Y2 to Y5 of the magnetic flux generated from the magnets 12 and 13 provided at the other portions. Will increase. Therefore, in the paths Y1 and Y5, the magnetic resistance increases and the amount of magnetic flux decreases, and the amount of magnetic flux in the adjacent paths Y2 and Y4 increases accordingly. Thereby, in the paths Y2 and Y4, a leakage magnetic flux that leaks to the outside of the yoke 3 is likely to be generated, and the thrust of the linear motor 100 may be reduced.

On the other hand, in the mover of the linear motor 50 according to the first embodiment, the amount of magnetic flux passing through the paths X1 to X5 is made uniform as described with reference to FIG. The thrust characteristics can be improved.

Further, the thrust magnet 12 that is first attached to the shaft 11 is positioned only by abutting against a retaining ring 14 that is previously fitted in the groove 11a. Further, the magnets 12 and 13 attached thereafter are also positioned by simply contacting the magnets 12 and 13 attached in front thereof. Therefore, it is possible to facilitate the positioning work when attaching the magnets 12 and 13 to the shaft 11.

In addition, since the hardened portion 15 is filled in the gap between the retaining ring 14 fitted after the magnets 12 and 13 are attached and the thrust magnet 12, the retaining ring 14 and Even when there is a gap between the thrust magnet 12, the magnets 12 and 13 can be more firmly fixed.

Further, thrust is applied to the magnets 12 and 13 attached to the shaft 11 in a direction parallel to the moving direction of the mover. Further, the inner peripheral surfaces of the magnets 12 and 13 and the outer peripheral surface of the shaft 11 are bonded by an adhesive or the like, and inertia force is applied to the bonded surfaces in a direction parallel to the thrust during acceleration / deceleration of the mover. Join. Since the adhesive surface between the inner peripheral surface of the magnets 12 and 13 and the outer peripheral surface of the shaft 11 is parallel to the direction in which the inertial force is applied, it may be difficult to exhibit sufficient adhesive strength against the inertial force.

In the mover according to the first embodiment, since the retaining ring 14 or the hardened portion 15 is provided on both sides in the direction along the thrust (inertia force) applied to the magnets 12 and 13, the thrust (inertia force) is generated. On the other hand, the magnets 12 and 13 can be mechanically fixed. Thereby, it can prevent more reliably that the magnets 12 and 13 shift | deviate by the thrust (inertial force) added to a needle | mover.

Further, for example, when a convex portion is formed on the outer peripheral surface of the shaft 11 instead of the retaining ring 14 to prevent the magnets 12 and 13 from being displaced by thrust (inertial force), the portion other than the convex portion is polished. It is necessary to form the thickness of the shaft 11. For this reason, there is a case where the manufacturing cost increases due to a request for processing accuracy or an increase in processing procedures.

In the first embodiment, the magnets 12 and 13 can be obtained simply by fitting the retaining ring 14 into the groove 11 a formed in the shaft 11 or filling the hardened portion 15 between the retaining ring 14 and the thrust magnet 12. Can be prevented from shifting due to thrust (inertial force), so that the manufacturing cost can be suppressed.

Moreover, since the shaft 11 and the magnets 12 and 13 become smaller as the linear motor 50 becomes smaller, the bonding surface between the magnets 12 and 13 and the shaft 11 becomes smaller. In this way, even when the adhesion surface between the magnets 12 and 13 and the shaft 11 is small and sufficient adhesion strength is difficult to be exhibited, the retaining rings 14 and the hardened portion 15 can surely shift the magnets 12 and 13. Can be prevented.

In the first embodiment, a plurality of magnets 12 and 13 are arranged in a Halbach arrangement in which thrust magnets are arranged at both ends. Therefore, the magnets 12 and 13 attached to the shaft 11 have fewer radial magnets 13 than the thrust magnets 12. In general, since the radial magnet 13 is more expensive than the thrust magnet 12, the mover according to the first embodiment that can reduce the number of the radial magnets 13 can reduce the manufacturing cost.

In addition, when a gap is not formed between the retaining ring 14 and the thrust magnet 12 to be attached later, the hardening portion 15 may not be provided. Further, the cross-sectional shape of the shaft 11 may be a circular shape as shown in FIG. 2 or a polygonal shape such as a quadrangle. Further, the shaft 11 may have a columnar shape as shown in FIG. 2 or a cylindrical shape. The shaft 11 may be a magnetic material or a non-magnetic material.

As described above, the mover according to the present invention is useful for a mover of a shaft type linear motor in which the shaft side functions as a mover.

1 casing, 1a through hole, 2 coil, 3 yoke, 4 linear bush, 11 shaft, 11a groove, 12 thrust magnet, 13 radial magnet, 14 retaining ring (fixed part), 15 hardened part, 50, 100 linear motor.

Claims (4)

1. A shaft having a rod-like shape extending in a first direction;
   A plurality of magnets exhibiting a cylindrical shape and through which the shaft passes,
   The plurality of magnets include a thrust magnet that generates a magnetic flux parallel to the first direction, and a radial magnet that generates a magnetic flux in the radial direction of the cylindrical shape,
   The thrust magnets and the radial magnets are alternately arranged so that the thrust magnets are arranged at both ends,
   A mover further comprising: a fixed portion made of a magnetic body disposed adjacent to the outer side along the first direction with respect to each of the thrust magnets disposed at both end portions.
2. A groove is formed in the shaft along the circumferential direction at a position where the fixing portion is provided,
   The mover according to claim 1, wherein the fixed portion is a retaining ring fitted into the groove.
3. Among the fixed parts, one fixed part is arranged so that the thrust magnet is in close contact, and the other fixed part is provided with a gap between the thrust magnet,
   The mover according to claim 2, further comprising a hardened portion that is filled and hardened in the gap.
4. A mover according to any one of claims 1 to 3,
   A stator that moves the mover along the first direction, and
   The stator is
   A casing in which at least the magnet is arranged in the shaft, and a through-hole is formed to penetrate both ends of the shaft;
   A coil provided inside the casing and surrounding the shaft;
   A linear motor comprising: a yoke provided inside the casing and outside the coil.

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