JPH02288278A - Magnetostrictive type actuator - Google Patents

Abstract

PURPOSE:To obtain a magnetostrictive actuator in which a micro displacement can be stably and desirably driven by providing driving force generating means made of a magnetic unit having magnetostriction, magnetic field generating means disposed around the unit, and means for shielding thermal conduction from an exterior to the unit. CONSTITUTION:An actuator has an air core coil 1, a magnetostrictive rod 3, and a thermally insulating layer 2 disposed around the rod 3 for shielding thermal conduction from the exterior of the rod to the rod. The coil 1 and permanent magnets 4a, 4b disposed oppositely to the longitudinal direction of the rod 3 form a magnetic circuit. A DC magnetic bias is applied in advance to the rod 3 at the magnets 4a, 4b to improve linearity between a control current and the displacement of the rod 3. The layer 2 is composed by spirally winding a water-cooled pipe 2a inside the coil 2, and cooling water managed to a predetermined temperature by a water temperature managing unit is supplied to the pipe 2a. Accordingly, a micro displacement can be stably and desirably driven irrespective of thermal disturbance.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention comprises a magnetic material that is distorted when magnetized by the application of an external magnetic field, that is, has magnetostriction, and that is displaced by the application of the external magnetic field. The present invention relates to a magnetostrictive actuator that can control the amount.

(Prior Art) With recent advances in measurement engineering and development in the field of precision machinery, there is a desire for the development of displacement drivers (actuators) that generate minute displacements on the micron order.

As this type of actuator, one is known in which a piezoelectric material such as PZT is used as a displacement generating element and a control voltage is applied to the displacement generating element. For this type of displacement generating element, the absolute drive displacement amount.

Good precision controllability, toughness, etc. are required.

By the way, the use of a magnetic material having magnetostriction (magnetostrictive material) is being considered as the displacement generating element that satisfies the above-mentioned requirements because it has greater rigidity than piezoelectric material. When using this type of magnetic material, a means for applying a control magnetic field to the magnetic material is provided as an actuator, but as a means for applying this magnetic field, a magnetic circuit such as an electromagnet is easily supplied with a control current. It is used because the magnetic field can be controlled.

(Problem to be Solved by the Invention) However, in an actuator equipped with such a magnetic circuit, when a control current is supplied to the magnetic circuit with the aim of securing the necessary displacement range, the magnetic circuit is affected by the influence of this current. The circuit generates heat, and the magnetic material thermally expands due to the influence of this heat, which becomes a major factor in reducing stability and controllability in minute displacement drive on the micron order.

An object of the present invention is to solve these conventional problems, and to provide a magnetostrictive actuator that can drive minute displacements with good stability and controllability without being affected by thermal disturbances.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a magnetostrictive actuator according to the present invention includes a driving force generating means made of a magnetic material having magnetostriction, and a driving force generating means disposed around the magnetic material. The gist of the present invention is to include a magnetic field generating means for applying a magnetic field to the magnetic body, and a means for shielding heat conduction from the outside of the magnetic body to the magnetic body, and a means for shielding heat conduction from the outside of the magnetic body to the magnetic body. There is.

A magnetostrictive actuator according to another aspect of the present invention includes a driving force generating means made of a magnetic material having magnetostriction, a magnetic field generating means disposed around the magnetic material and applying a magnetic field to the magnetic material, and a driving force generating means made of a magnetic material having magnetostriction; The gist is that the device is equipped with a temperature control means for keeping the body at a constant temperature.

(Function) According to the magnetostrictive actuator having the above configuration, an electromagnet is used as the magnetic field generating means, and even if a temperature rise occurs outside the magnetic material, such as when the electromagnet generates heat due to the current supplied to the electromagnet, the magnetic material The means for shielding heat conduction placed around the magnetic body shields heat conduction from the outside of the magnetic body to the magnetic body, making it possible to control small displacements with stability and controllability without being affected by thermal disturbances. Can be driven well.

Further, the same effect can be obtained by using a temperature control means consisting of a mechanism such as flowing cooling water inside the magnetic body or forcing the magnetic body to cool with air (Example).Hereinafter, regarding the magnetostrictive actuator according to the present invention,
This will be explained with reference to FIGS. 1 and 2.

In FIG. 1 showing an embodiment of the magnetostrictive actuator according to the present invention, the magnetostrictive actuator includes an air-core coil 1 as a part of the magnetic field generating means, and a magnetostrictive rod 3 (diameter 10 (1), length 50■), and a thermal insulating layer 2 disposed around the magnetostrictive rod 3 as a means for shielding heat conduction from the outside of the magnetostrictive rod 3 to the magnetostrictive rod 3. There is.

The magnetostrictive rod 3 is made of rare earth/iron-based Laves type intermetallic compound T b O, 3D Y O, 7F e 1
．． 9 compositions of magnetic materials are used. A stay 6 is attached to one end of the magnetostrictive rod 3, and serves as a joint when connecting the deformation amount of the magnetostrictive rod 3 to a driven device such as an XY stage.

Further, the air-core coil 1 is connected to a power source (not shown) for supplying a control current to the air-core coil 1. A permanent magnet 4a is arranged to face the air-core coil 1 and the magnetostrictive rod 3 in the longitudinal direction.

4b constitutes a magnetic circuit. This permanent magnet 4a,
4b, a direct current magnetic bias is applied to the magnetostrictive rod 3 in advance to improve the linearity of the relationship between the control current and the amount of displacement of the magnetostrictive rod 3, and to adjust the displacement to a standard appropriately set in the direction of the arrow 7. It is intended to be done within ± of the value.

The thermal insulation layer 2 has a structure in which a water-cooled vibrator 2a is spirally wound inside the air-core coil 1, and the water-cooled vibrator 2a is heated to a constant temperature by a water temperature control device such as a constant temperature bath (not shown). Temperature-controlled cooling water is supplied to the

Therefore, in this embodiment, in the water-cooled vibrator 2a,
By supplying temperature-controlled cooling water, conduction of heat generated in the air-core coil 1 to the magnetostrictive rod 3 by the control current supplied to the air-core coil 1 is interrupted, and the temperature of the magnetostrictive rod 3 is also controlled. Therefore, minute displacements can be driven with good stability and controllability without being affected by thermal disturbances.

Therefore, by performing step control while controlling the temperature of the cooling water to, for example, ±1°C or less, it is possible to perform stable and good minute displacement control as shown in Figure 2, and it is possible to perform fine displacement control from micron order to submicron order. It has become clear that this method can be applied to minute displacement control such as positioning.

In the above embodiment, the water cooling pipe 2a is arranged around the magnetostrictive rod 3 to shield heat conduction from the outside of the magnetostrictive rod 3, but instead of the cooling water in the water cooling pipe 2a, air, Gases such as nitrogen, oxygen, argon, etc. may be used, or these gases may be used as an atmosphere without being inserted into the pipe. It goes without saying that a generally known heat insulating layer may be formed. [Effects of the Invention] As explained above, in the magnetostrictive actuator according to the present invention, the electromagnet is used as the magnetic field generating means. used,
Even if a temperature rise occurs outside the magnetic material, such as when the electromagnet generates heat due to the current supplied to the electromagnet, there is a means to shield heat conduction placed around the magnetic material. In order to shield this heat conduction to the magnetic material,
Furthermore, since the temperature is maintained at a constant temperature by the temperature control means, minute displacements can be driven with good stability without being affected by thermal disturbances.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an embodiment of a magnetostrictive actuator according to the present invention, and FIG. 2 is a characteristic diagram of the actuator according to the present invention obtained by driving minute displacement control. 1... Air core coil 2... Thermal insulation layer 3... Magnetostrictive rod

Claims (2)

[Claims] (1) A driving force generating means made of a magnetic material having magnetostriction;
a magnetic field generating means disposed around the magnetic body to apply a magnetic field to the magnetic body; a means disposed around the magnetic body for shielding heat conduction from the outside of the magnetic body to the magnetic body; A magnetostrictive actuator comprising: (2) a driving force generating means made of a magnetic material having magnetostriction;
A magnetostrictive actuator comprising: magnetic field generating means disposed around the magnetic body and applying a magnetic field to the magnetic body; and temperature adjusting means keeping the magnetic body at a constant temperature.