PURPOSE: To prevent the occurrence of de-polarization and nullify the reversal of polarity for expanding an application area by using an electrostrictive element not subjected to an electric field depolarization process, and having a displacement amount and Curie temperature equal to or above the predetermined values, and capability somewhere between piezoelectric and electrostrictive characteristics.
CONSTITUTION: A hydraulic pressure regulating valve has a spool 6 moving right and left, upon actuating one electrostrictive element 4 of two such elements, thereby closing a valve 2 and opening each of valves 1 and 3. As a result, oil is introduced through the valve 1 and high pressure is generated in one cylinder chamber 9 of two such chambers. Also, oil after the valve 3 is discharged to the outside of a system through a communication pipe 8. Consequently, a cylinder 7 moves right. On the other hand, when the other electrostrictive element 5 is actuated, the cylinder 7 moves left, according to action similar to the above. In this constitution, the elements 4 and 5 are made of an electrostrictive element not subjected to an electric field depolarization process, and having a displacement amount equal to or above 0.06%, Curie temperature equal to 150°C or above, and capability somewhere between piezoelectric and electrostrictive characteristics.
AOKI SHINICHI
TSUDA TAKESHI
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