JPH06197573A - Actuator and pump incorporating magnetostriction element - Google Patents

Abstract

PURPOSE:To simplify the structure of a magnetostriction actuator or magnetostriction pump utilizing a magnetostriction element, and, at the same time, to reduce the number of parts used in the actuator or pump. CONSTITUTION:This is actuator is composed of a magnetostriction element 11, cylindrical elastic body 12 incorporating the element 11, casing 13 housing the elastic body 12 and provided with a hydraulic pressure chamber 16 on the top of the elastic body 12, piston 17 which is installed to the casing 13 in a slidable state while the piston is brought into contact with the liquid contained in the chamber 16, and coil 14 surrounding the casing 13. The pump incorporating the magnetostriction element is provided with a check valve in place of the piston 17 for sucking up the liquid into the liquid chamber and another check valve for discharging the liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostrictive actuator or a magnetostrictive pump using a magnetostrictive element.

[0002]

2. Description of the Related Art It has been attempted to use a piezoelectric (electrostrictive) element or a magnetostrictive element having a high response speed as an actuator. For example, an actuator driven by an electrostrictive body is disclosed in Japanese Patent Laid-Open No.
As disclosed in JP-A-2-28507, the electrostrictive element laminate contracts the pump chamber above it to send the liquid to the working chamber with a check valve for discharge, and pushes up the output rod. Piezoelectric (piezoelectric) actuators are used for shock absorbers of automobile suspensions (Sato et al., "Development of Piezo-TEMS -Cersior Suspension-", Toyota Technology, Vol. 39, No. 2, December 1989, 17). See page 25). In this case, the minute expansion of the piezoelectric element is increased by the displacement magnifying mechanism (hydraulic system).

In order to expand and contract the piezoelectric element, it is necessary to apply a high voltage of several hundreds of volts, electrodes are provided at both ends of the element, and a connecting mechanism therefor is required, and in some cases, a sealing mechanism is also required. It is necessary, has a complicated structure, and has a large number of parts. Further, a magnetostrictive actuator is proposed in JP-A-2-237477, a coil is arranged around the magnetostrictive element, and a permanent magnet is arranged around the coil.
A pair of magnetic pole yokes that guide the magnetic flux from both end faces of the permanent magnet to the magnetostrictive element are arranged, and are moved by the magnetostrictive element and a moving member is attached to one of the magnetic pole yokes. Magnetostrictive element, like the electrostrictive element, its elongation (displacement)
Is very small, so a displacement magnifying mechanism by hydraulic pressure (hydraulic pressure) is provided in order to obtain the acting movement amount as an actuator.

There are various types of pumps (for example, Akira Hashimoto: Introduction to Hydraulic Technology, Industrial Research Committee, (19
84), pp. 23-43).

[0005]

The structure of the conventional electrostrictive actuator or magnetostrictive actuator is complicated (the number of parts is large), which is an obstacle to miniaturization and high reliability of the device. Further, the conventional pump generally has a complicated structure, and it is difficult to control the minute flow rate.

An object of the present invention is to provide a magnetostrictive actuator and a magnetostrictive pump which have a simple structure and a small number of parts.

[0007]

Means for Solving the Problems The above-mentioned object is to provide a magnetostrictive element, a cylindrical elastic body having the magnetostrictive element inside, a cylindrical elastic body inside and an upper part of the cylindrical elastic body. An actuator having a magnetostrictive element, which comprises a casing having a hydraulic chamber, a piston in contact with the liquid in the liquid chamber and slidably provided on the casing, and a coil surrounding the casing. .

Further, a magnetostrictive element, a cylindrical elastic body having the magnetostrictive element inside, a casing having the cylindrical elastic body inside and a hydraulic chamber above the cylindrical elastic body, The object of the present invention is also achieved by a pump having a built-in magnetostrictive element, which comprises a check valve for sucking a liquid into a liquid chamber, a check valve for discharging a liquid from the liquid chamber, and a coil surrounding the casing. To be achieved.

[0009]

The function of the magnetostrictive element changes when a magnetic field is applied. When the material is a positive magnetostrictive material, the magnetostrictive element extends in the element axial direction in the magnetic field direction when a magnetic field is applied (magnetostrictive element 1A shown by the broken line in FIG. 1). At this time, the magnetostrictive element contracts in the radial direction at the same time, and the volume of the magnetostrictive element does not substantially change. In the present invention, the magnetostrictive element is pushed into the tubular elastic body in a state where the magnetostrictive element is extended (contracted in the radial direction) by applying a magnetic field.
Further, the tubular elastic body (the elastic body 2A shown by the broken line in FIG. 1) in this state is pushed into the inside of the casing 3,
This elastic body is sandwiched between the magnetostrictive element and the casing and installed with a contraction amount y. When the magnetic field application is released, the magnetostrictive element returns to contract (as indicated by 1B in FIG. 1) and expands in the radial direction (by Δr), and the elastic body 2B pushes against the magnetostrictive element 1B. And contracts in the radial direction and extends in the longitudinal direction (by ΔL). The contraction amount x of the elastic body at this time is larger than the contraction amount y when the magnetic field is applied. Rubber, metal, plastic (F
(Including RP).

Therefore, the volume V of the cylindrical elastic body when a magnetic field is applied
The volume change ΔV between _H and the volume V ₀ without a magnetic field is represented by the following mathematical expression (A) with reference to FIG. 1. ΔV = V _H −V ₀ V _H = π {R ² − (r−Δr) ² } (L−ΔL) V ₀ = π (R ² −r ² ) L ΔV = π [2rL · Δr− (R ² -R ² ) ΔL]

[0011]

[Equation 1]

In the equation, μ is the Poisson's ratio of the elastic body,
Letting λ _S be the magnetostriction of the magnetostrictive element in the axial direction,

[0013]

[Equation 2]

And therefore,

[0015]

[Equation 3]

For example, a general rubber material (Poisson's ratio μ = 0.5) is used as the tubular elastic body, and a magnetostrictive element (diameter 6 mm ×
Length 50 mm), r = 3, L = 50, casing inner diameter R 4 mm, magnetostriction of magnetostrictive element λ _S = 1
At 000 × 10 ^-6 , a volume change of ΔV = 0.31 mm ³ occurs. In the present invention, the hydraulic chamber of the casing is provided above the magnetostrictive element and the elastic body, and the volume change Δ of the elastic body with and without magnetism applied in this hydraulic chamber.
V is generated, and the liquid in the hydraulic chamber can be pushed out by ΔV from the hydraulic chamber. This pushed liquid can move the piston slidably provided in the casing, and the action of the actuator can be obtained. Further, by providing a check valve for sucking liquid into the liquid chamber and a check valve for discharging liquid from the liquid chamber, a pump having a discharge amount of ΔV per cycle can be obtained.

Further, as shown in the formula (A), in order to increase ΔV, a material having a Poisson's ratio of the elastic body as large as possible is desirable, and a rubber material or the like is particularly desirable.
Further, it is preferable that R / r is also small, and 1 <R / r <1.2 is preferable.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings by way of example embodiments of the present invention. In the magnetostrictive actuator and the magnetostrictive pump according to the present invention, the magnetostrictive element and the tubular elastic body act on the liquid in the hydraulic chamber of the casing. First, the magnetostrictive element and the tubular (cylindrical) shape.
The incorporation of the elastic body into the casing will be described with reference to FIG.

The magnetostrictive element 11 is manufactured and prepared according to a usual method. For the magnetostrictive material, for example, Tb _0.3 Dy
_0.7 Fe _1.9 etc. A cylindrical cylinder made of rubber is prepared as the elastic body 12, and its inner diameter is slightly smaller than the diameter of the magnetostrictive element 11 when a magnetic field is applied, and its outer diameter is slightly larger than the inner diameter of the casing 13. The casing 13 is made of a non-magnetic metal material, and the coil 14 for generating a magnetic field is made so as to surround the casing 13.

As shown in FIG. 2, a current is passed through the coil 14 to generate a magnetic field, the magnetostrictive element 11 is disposed at the center of the coil, and the magnetostrictive phenomenon extends the magnetostrictive element in the longitudinal direction (the element diameter is Shrinkage), while maintaining this state, the magnetostrictive element 11 is pushed into the through hole of the cylindrical elastic body 12. Then, the elastic body 12 is maintained in the coil magnetic field, and the elastic body is pushed into the casing 13. In FIG. 2, the coil 14 is lowered together with the magnetostrictive element 11, and the magnetostrictive element 11 and the elastic body 12 are sequentially pushed into the casing 13.
On the contrary, it is also possible to assemble the magnetostrictive element by fitting the elastic body and the casing in order.

FIGS. 3 and 4 are schematic sectional views of the magnetostrictive actuator according to the present invention. The casing 13 incorporated in FIG.
A cylinder portion is formed which forms a hydraulic chamber 16 filled with water. FIG. 3 shows the case where no magnetic field is applied, and FIG. 4 shows the case where a magnetic field is applied by the coil 14. The sliding piston 17 has an O-ring 1 as a sealing means for preventing liquid leakage.
8 is attached.

As shown in FIG. 3, when the current flow to the coil 14 is stopped and the magnetic field is not applied to the magnetostrictive element 11, the magnetostrictive element 11 contracts in the longitudinal direction more than in the assembly in FIG. Expand radially. Due to the lateral expansion of the element 11, the elastic body 12 contracts by Δr in the radial direction and expands by ΔL in the longitudinal direction (see FIG. 1), and the elastic body 12 decreases in volume (contracts) by ΔV as compared with when a magnetic field is applied. It will be. At this time, the storage capacity of the liquid (for example, oil) 15 in the hydraulic chamber 16 of the casing 13 is increased by ΔV, the liquid that pushes up the piston 17 is pushed back to the hydraulic chamber 16, and the piston 17 descends ( Usually, a weak force that pushes down the piston 17 is applied in advance).

Next, as shown in FIG. 4, a current is applied to the coil 14 to generate a magnetic field, and the magnetic field is applied to the magnetostrictive element 11, so that the magnetostrictive effect causes the magnetostrictive element 11 to extend in the longitudinal direction and in the radial direction. Shrink. As a result, as described above, the volume of the elastic body 12 increases by ΔV, the accommodation capacity of the hydraulic chamber 16 decreases by that amount, and the liquid 15 is pushed out from the hydraulic chamber,
Push up the piston 17. For example, assuming that the diameter of the piston 17 is 1 mm, if the volume change (increase) of ΔV = 0.31 mm ³ described above, the piston 17 is moved by a distance of about 0.39 mm. Thus, a magnetostrictive actuator capable of reciprocating the piston can be obtained.

FIG. 5 is a schematic sectional view of the magnetostrictive pump according to the present invention, in which the casing 13 incorporated in FIG. 2 is provided with a liquid suction check valve 21 and a liquid discharge check valve 22. A cylinder portion forming 23 is attached. In the case of FIG. 5, the cylindrical elastic body 13 is applied without applying a magnetic field.
Due to the ΔV volume contraction of, the check valve for liquid suction 21 is opened and the liquid is put into the liquid chamber 23 from the reserve tank 25.
On the other hand, the liquid discharge check valve 22 is closed. A current is applied to the coil 14 to generate a magnetic field, which causes the magnetostrictive element 11 to be distorted and causes the ΔV volume expansion of the elastic body 12 to cause the liquid in the hydraulic chamber 23 to pass through the liquid discharge check valve 22 to the hydraulic system 26. send. At this time, the check valve 2 for liquid suction
1 will be closed.

In this way, a magnetostrictive pump having a discharge amount of ΔV per cycle of magnetic field application of liquid (oil or the like) can be obtained. In the above description, a magnetostrictive material having a positive magnetostriction coefficient that extends in the magnetic field direction when a magnetic field is applied is used, but a magnetostrictive material having a negative magnetostriction coefficient can be used as well.

[0026]

As described above, the actuator and pump having the magnetostrictive element according to the present invention have a very simple structure as compared with the conventional case, and the number of components is small. Therefore, it is possible to significantly reduce the occurrence of troubles and to provide a magnetostrictive actuator and a magnetostrictive pump with improved reliability.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating changes in a magnetostrictive element and a tubular elastic body according to the present invention.

FIG. 2 is a schematic exploded view illustrating assembly of a magnetostrictive element, a tubular elastic body, and a casing according to the present invention.

FIG. 3 is a schematic sectional view of the magnetostrictive actuator according to the present invention when a magnetic field is not applied.

FIG. 4 is a schematic sectional view of the magnetostrictive actuator according to the present invention when a magnetic field is applied.

FIG. 5 is a schematic sectional view of the magnetostrictive pump according to the present invention when a magnetic field is not applied.

[Explanation of symbols]

 1A ... Magnetostrictive element when magnetic field is applied 1B ... Magnetostrictive element when magnetic field is not applied 2A ... Cylindrical elastic body when magnetic field is applied 2B ... Cylindrical elastic body when magnetic field is not applied 3 ... Casing 11 ... Magnetostrictive element 12 ... Cylindrical elastic body 13 ... Casing 14 ... Coil 15 ... Liquid 16 ... Liquid pressure chamber 17 ... Piston 21 ... Liquid suction check valve 22 ... Liquid discharge check valve 23 ... Liquid pressure chamber 25 ... Reserve tank

Claims (2)

[Claims] 1. A magnetostrictive element (11), a cylindrical elastic body (12) having the magnetostrictive element inside, and a hydraulic chamber provided inside the cylindrical elastic body and above the cylindrical elastic body. A casing (13) having (16), and a piston (1) in contact with the liquid (15) in the liquid chamber and slidably provided on the casing.
7) and a coil (14) surrounding the casing, the actuator having a built-in magnetostrictive element. 2. A magnetostrictive element (11), a cylindrical elastic body (12) having the magnetostrictive element inside, and a hydraulic chamber provided with the cylindrical elastic body inside and above the cylindrical elastic body. A casing (13) having (23), a check valve (21) for sucking liquid into the liquid chamber, and a check valve (22) for discharging liquid from the liquid chamber.
And a coil (14) surrounding the casing, the pump having a built-in magnetostrictive element.