JP2002058269A - Supermagnetostrictive actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supermagnetostrictive actuator for not bringing about a measuring error or an actuation fault when a measuring instrument or a facility exists in a circumference by suppressing a leakage magnetic flux as much as possible and not bringing about the actuation fault when a magnetic element is existed closely. SOLUTION: Permanent magnets (6B, 6T) for magnetic biases are arranged at both ends of a supermagnetostrictive rod (2), and are mounted in a cylindrical yoke (4) formed of a highly magnetic permeable material to form a closed magnetic path. An upper surface (4T) of the yoke (4) is slidably fitted along an inside of a peripheral surface (4S), and corners (4b, 4s and 4t) easy to bring about the leakage magnetic flux are finished in a rounded state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetostrictive actuator used for converting electric energy into mechanical energy.

[0002]

FIG. 3 shows a conventional giant magnetostrictive actuator 3.
0, a cylindrical permanent magnet 32 and a giant magnetostrictive rod 3
3 and a pair of upper and lower yokes 34 and 35 for connecting these upper ends and lower ends thereof to form a closed magnetic path.

In order to apply a magnetic bias to the giant magnetostrictive rod 33, an electromagnet 36 formed by winding a coil around the giant magnetostrictive rod 33 is provided in a space surrounded by the permanent magnet 32 and the yokes 34 and 35. Is arranged. Further, a spring 37 for applying a prestress to the giant magnetostrictive rod 33 is disposed between the casing 31 and the yoke 35.

According to this, a magnetic bias is applied to the giant magnetostrictive rod 33 via the yokes 34 and 35 by the permanent magnet 32, and a current is applied to the electromagnet 36 in a state where a prestress is applied by the spring 37. When supplied, the giant magnetostrictive rod 33 expands and contracts according to the magnitude of the magnetic force, and the push rod 38 provided at the tip of the giant magnetostrictive rod 33 moves, so that the displacement can be taken out as mechanical power.

[0005]

However, in this case, although the main magnetic flux of the magnetic force generated by the permanent magnet 32 and the electromagnet 36 flows in the closed magnetic circuit, the leakage magnetic flux φ is easily generated between the yokes 34 and 35. There was a problem.

That is, when a magnetic field generated by the permanent magnet 32 forms a closed magnetic path from the yoke 35 side to the opposite yoke 34 side through the giant magnetostrictive rod 33 disposed at the center thereof, Since the giant magnetostrictive rod 33 is interposed and the yokes 34 and 35 are vertically divided, a leakage magnetic flux φ is easily generated therebetween. When the magnetic force generated by the electromagnet 36 forms a closed magnetic path from the yoke 34 side to the opposite yoke 35 side through the permanent magnet 32 disposed around the yoke 34, the permanent magnet 32 is placed in the closed magnetic path. Since the yokes 34 and 35 are vertically separated by being interposed,
During this time, a leakage magnetic flux φ is likely to occur.

For this reason, when there are measuring instruments and equipment around the actuator 30 which are susceptible to the magnetic field, a measurement error or malfunction occurs, or when a magnetic substance exists around the actuator 30, the magnetic field leaks more easily. 30 has a problem of causing a malfunction.

Further, the yoke 35 includes an annular member 35a integrally attached to the permanent magnet 32 and a giant magnetostrictive rod 3
3, a gap G is formed between the two members so that the giant magnetostrictive rod 33 can freely expand and contract.
Is also a magnetic resistance, causing leakage magnetic flux.

Accordingly, the present invention minimizes the generation of magnetic flux leakage so that measurement errors and malfunctions do not occur when measuring instruments and equipment are present in the surroundings, and when magnetic materials are present nearby. Another object of the present invention is to provide a giant magnetostrictive actuator that does not cause a malfunction.

[0010]

In order to solve this problem, the present invention provides a giant magnetostrictive actuator which expands and contracts a giant magnetostrictive rod by a change in magnetic force to output its displacement. The bottom surface and the top surface of the cylindrical yoke are brought into contact with each other through a pair of permanent magnets for magnetic bias provided coaxially at both ends thereof, and a coil is wound around the giant magnetostrictive rod to form an electromagnet. The cylindrical yoke is formed such that a bottom surface portion is fixed to the peripheral surface portion, and an upper surface portion is slidably fitted in the axial direction along the inside of the peripheral surface portion, and has a maximum relative magnetic permeability of 1000 or more. It is formed of a magnetically permeable material, and a corner formed on the surface of the yoke is rounded.

According to the present invention, both ends of the giant magnetostrictive rod are
Since the bottom surface and the top surface of the cylindrical yoke are brought into contact with each other via the permanent magnet for magnetic bias, they form a closed magnetic path. At this time, the permanent magnet for magnetic bias is provided coaxially with the giant magnetostrictive rod, and there is no need to arrange a cylindrical permanent magnet on the peripheral surface thereof, so that the yoke is not divided vertically. That is, since the bottom surface and the top surface of the cylindrical yoke are magnetically connected via the peripheral surface,
Almost no magnetic flux leakage occurs.

Also, since the upper surface of the cylindrical yoke is fitted slidably in the axial direction along the inside of the peripheral surface,
There is almost no gap between the upper surface and the peripheral surface, and the generation of leakage magnetic flux is suppressed. Furthermore, the cylindrical yoke has a maximum relative permeability of 1
Since it is formed of a material having a high magnetic permeability of 000 or more, it is easy to pass a magnetic field, and the corners formed on the surface of the yoke are round-finished, and there are no sharp corners that easily cause leakage magnetic flux. The generation of the leakage magnetic flux is suppressed in both the material and the shape.

When a current flows through an electromagnet formed by winding a coil around the giant magnetostrictive rod, the magnetic force acts on the giant magnetostrictive rod without waste through the yoke, and a large displacement is obtained with a relatively small current. be able to.

[0014]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a sectional view showing a giant magnetostrictive actuator according to the present invention.

The giant magnetostrictive actuator 1 of this embodiment is designed to expand and contract a giant magnetostrictive rod 2 by a change in magnetic force to output the displacement, and a cylindrical yoke is provided in a casing 3 made of a nonmagnetic material. 4, a giant magnetostrictive rod 2 is provided at the center thereof, and a coil is wound around the giant magnetostrictive rod 2 to form an electromagnet 5.

As the giant magnetostrictive rod 2, a cylindrical ETR is used.
EMATERFENOL-D (trade name of Etrimer)
And permanent magnets 6B and 6T for magnetic bias, which are formed to have the same diameter as the giant magnetostrictive rod 2, are provided coaxially at both ends. As the permanent magnets 6B and 6T, neodymium / iron / boron magnets or SmCo magnets belonging to the class having the strongest magnetic force among rare earth magnets are used.
The giant magnetostrictive rod 2 is in contact with the bottom surface 4B and the top surface 4T of the cylindrical yoke 4 via the permanent magnets 6B and 6T,
A closed magnetic path is formed together with the yoke 4.

The cylindrical yoke 4 has a bottom surface portion 4B fixed to the cylindrical peripheral surface portion 4S and an upper surface portion 4T formed in a disk shape, and slides axially along the inside of the peripheral surface portion 4S. It is fitted as possible. A fluororesin coating film 7 is formed on the entire surface of the upper surface 4T and the inner surface of the peripheral surface 4S in order to reduce the coefficient of friction when sliding with each other.

Further, a bottom portion 4B, a peripheral portion 4S, and a top portion 4
Each member of T is 45 permalloy, 50 permalloy, 78
Made of high magnetic permeability material with a maximum relative permeability of 1000 or more such as permalloy, pure iron, silicon steel, soft magnetic amorphous, directional silicon steel, permendur, alpalm, sendust, supermalloy with Mo, supermalloy with Cu, etc. ing. Further, all corners are rounded so that sharp corners such as a portion 4b where the bottom surface 4B and the peripheral surface 4S are continuous, an upper edge 4s of the peripheral surface 4S, and a periphery 4t of the upper surface 4T are not exposed. Finished.

The upper surface 4 is provided in the casing 3.
A spring 8 for applying a prestress to the giant magnetostrictive rod 2 is disposed from outside the T, and the giant magnetostrictive rod 2 is provided on the upper surface 4T.
Non-magnetic material push rod 9 for transmitting the displacement of the outside
Is provided.

The above is one configuration example of the present invention, and its operation will be described below. Permanent magnets 6 at both ends of giant magnetostrictive rod 2
B and 6T are arranged and attached to the center of the cylindrical yoke 4, and the coil wound in a cylindrical shape is mounted in the gap between the giant magnetostrictive rod 2 and the yoke 4 to form the electromagnet 5. Next, the upper surface portion 4T is attached to the distal end side of the giant magnetostrictive rod 2 and is fitted into the peripheral surface portion 4S, and after being put in the casing 3,
Set the spring 8 and finally cover 3T of the casing 3
Tighten.

As a result, a closed magnetic path is formed by the giant magnetostrictive rod 2 and the yoke 4, and the magnetic force of the permanent magnets 6B and 6T passes through the closed magnetic path and acts on the giant magnetostrictive rod 2 as a magnetic bias. At this time, since the permanent magnet for magnetic bias is provided coaxially with the giant magnetostrictive rod 2 and the cylindrical permanent magnet is not disposed on the peripheral surface 4S of the yoke 4, the yoke 4 is vertically divided. Not even.

That is, the cylindrical yoke 4 has its peripheral surface 4
Since the bottom surface 4B and the top surface 4T are magnetically connected via S, almost no leakage magnetic flux is generated. Further, since the upper surface portion 4T of the cylindrical yoke 4 is fitted slidably in the axial direction along the inside of the peripheral surface portion 4S, the upper surface portion 4T and the peripheral surface portion 4S are in close contact with each other, and there is almost no gap therebetween. The generation of leakage magnetic flux is also suppressed.

Further, the cylindrical yoke has a maximum relative magnetic permeability of 100.
Since it is formed of a material having a high magnetic permeability of 0 or more, a magnetic field easily passes therethrough, and further, a portion 4b where the bottom surface portion 4B and the peripheral surface portion 4S are continuous, an upper edge 4s of the peripheral surface portion 4S, a peripheral edge 4t of the upper surface portion 4T, and the like. Since the corners formed on the surface of the yoke are rounded and there are no sharp corners that easily generate leakage magnetic flux, generation of leakage magnetic flux is suppressed both in material and shape.

Further, by tightening the lid 3T of the casing 3, the resilience of the spring 8 is transmitted to the giant magnetostrictive rod 2 via the upper surface 4T of the yoke 4, and a prestress is applied.

Next, when a DC or AC current is applied to the coil of the electromagnet 5, the electromagnet 5 forms a magnetic field that passes through a closed magnetic path composed of the giant magnetostrictive rod 2 and the cylindrical yoke 4, and the magnetic field varies in accordance with the magnetic field strength. The giant magnetostrictive rod 2 expands and contracts.
In the experiment, when a current of ± 1.7 (A) was supplied to the coil of the electromagnet 5, a magnetic force having a magnetic field strength of 450 (Oe) acted on the giant magnetostrictive rod 2 and the tip of the push rod 9 ±± 1.
A displacement of 3 μm was generated, and it was confirmed that it could be used in the range of DC to 3 kHz.

In this case as well, since the generation of the leakage magnetic flux is suppressed in the same manner as described above, the energy loss is small, and if there is a measuring device or equipment around the actuator 1 which is easily affected by the magnetic field, a measurement error or malfunction may occur. Also does not cause. Further, even if there is a magnetic material around the actuator 1, the magnetic flux leaks due to the influence, or the actuator 1
Does not cause malfunction. Therefore, it can be used as a positioning actuator or a high-frequency actuator in equipment that is easily affected by minute magnetic fields, such as semiconductor manufacturing equipment and liquid crystal-related equipment.

[0027]

As described above, according to the present invention, the generation of magnetic flux leakage from the yoke can be suppressed as much as possible, thereby reducing measurement errors and malfunctions when there are measuring instruments and equipment around. There is an extremely excellent effect that the output characteristics as rated can be obtained without causing malfunction and without causing a malfunction even when a magnetic material is present nearby.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a giant magnetostrictive actuator according to the present invention.

FIG. 2 is a sectional view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Giant magnetostrictive actuator 2 ... Giant magnetostrictive rod 3 ... Casing 4 ... Cylindrical yoke 4B ... Bottom part 4T ... Top part 4S ... Peripheral part 5 ... Electromagnet 6B, 6T ... ... permanent magnet 7 ... coating film 8 ... spring

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayoshi Tatsu 1-3-3 Azaminominamiminami, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside Moritex Yokohama Technical Center Co., Ltd.

Claims (3)

[Claims] 1. A giant magnetostrictive rod according to a change in magnetic strength.
A giant magnetostrictive actuator which expands and contracts and outputs its displacement, wherein the giant magnetostrictive rod (2) is cylindrically formed via magnetic bias permanent magnets (6B, 6T) provided coaxially at both ends thereof. An electromagnet (5) is formed by abutting the bottom surface (4B) and the top surface (4T) of the yoke (4) and winding a coil around the giant magnetostrictive rod (2). The bottom surface portion (4B) of the yoke (4) has a peripheral surface portion (4B).
S), the upper surface (4T) is fitted slidably in the axial direction along the inside of the peripheral surface (4S), and is formed of a high magnetic permeability material having a maximum relative magnetic permeability of 1000 or more. And a corner portion (4b, 4s, 4t) formed on the surface of the yoke (4) is round-finished. 2. The super-magnetostrictive rod, wherein the cylindrical yoke (4) is housed in a casing (3) formed of a non-magnetic material, and inside the casing (3) from outside the upper surface (4T). 2. The giant magnetostrictive actuator according to claim 1, wherein a spring (8) for applying a prestress is arranged on (2). 3. A coating film (7) of a fluororesin is formed on at least one of a sliding portion between a peripheral surface (4S) and an upper surface (4T) of the yoke (4). Giant magnetostrictive actuator.