Actuator

Abstract

An actuator includes an electromagnetostrictive element that has one end located on a front side and the other end located on a rear side, an output shaft that penetrates the electromagnetostrictive element and is pressurized toward the rear side of the electromagnetostrictive element, a housing that houses therein the electromagnetostrictive element and the output shaft, bearing portions that respectively support the front side and the rear side of the output shaft, a bias spring provided between the rear side of the output shaft and the housing, and a displacement sensor that detects a position in an axial direction of the shaft.

What is claimed is:  
     
         1 . An actuator comprising: 
 an electromagnetostrictive element that has one end located on a front side and the other end located on a rear side;    an output shaft that penetrates the electromagnetostrictive element and is pressurized toward the rear side of the electromagnetostrictive element;    a housing that houses therein the electromagnetostrictive element and the output shaft;    bearing portions that respectively support the front side and the rear side of the output shaft;    a bias spring provided between the rear side of the output shaft and the housing; and    a displacement sensor that detects a position in an axial direction of the shaft.    
     
     
         2 . An actuator comprising: 
 an electromagnetostrictive element that has one end located on a front side and the other end located on a rear side;    a first output shaft that penetrates the electromagnetostrictive element and is pressurized toward the rear side of the electromagnetostrictive element;    a housing that houses therein the electromagnetostrictive element and the first output shaft;    a second output shaft that houses therein the front side of the first output shaft and is pressurized toward the front side of the electromagnetostrictive element; and    bearing portions that respectively support the rear side of the first output shaft and the second output shaft.    
     
     
         3 . An actuator as claimed in  claim 2 , further comprising bias springs provided between the rear side of the first output shaft and the housing and between the second output shaft and the housing.  
     
     
         4 . An actuator comprising: 
 an electromagnetostrictive element that has one end located on a front side and the other end located on a rear side;    a first output shaft that penetrates the electromagnetostrictive element and is pressurized toward the rear side of the electromagnetostrictive element;    a housing that houses therein the electromagnetostrictive element and the first output shaft;    a rear-side sleeve that rotatably supports the rear side of the first output shaft;    a second output shaft that houses therein the front side of the first output shaft and is pressurized toward the front side of the electromagnetostrictive element;    a front-side sleeve that rotatably supports the second output shaft; and    a device for making the first output shaft and/or the second output shaft movable in the axial direction and rotating either one of the first output shaft and the second output shaft.    
     
     
         5 . An actuator as claimed in  claim 4 , wherein the first output shaft and the second output shaft are able to move relatively to each other in the axial direction and to mutually transmit the rotation thereof.  
     
     
         6 . An actuator comprising: 
 an electromagnetostrictive element that has one end located on a front side and the other end located on a rear side;    a rear-side center shaft pressurized toward the rear side of the electromagnetostrictive element;    a rear-side bearing portion provided between rear-side center shaft and the housing to make the rear-side center shaft rotatable relative to the housing;    an output shaft pressurized toward the front side of the electromagnetostrictive element;    a front-side sleeve that rotatably supports the output shaft relative to the housing; and    a front-side bearing portion that supports the output shaft rotatably relative to the housing and movably in the axial direction.    
     
     
         7 . An actuator as claimed in  claim 6 , further comprising a rotation transmission shaft capable of moving relatively in the axial direction and mutually transmitting rotation which is provided between the front side and the rear side of the electromagnetostrictive element.  
     
     
         8 . An actuator as claimed in  claim 5 , further comprising a bias spring provided between the output shaft and the front-side sleeve.  
     
     
         9 . An actuator as claimed in  claim 4 , wherein the electromagnetostrictive element is a Giant-magnetostrictive element.  
     
     
         10 . An actuator as claimed in  claim 5 , wherein the electromagnetostrictive element is a Giant-magnetostrictive element.  
     
     
         11 . An actuator as claimed in  claim 6 , wherein the electromagnetostrictive element is a Giant-magnetostrictive element.  
     
     
         12 . An actuator as claimed in  claim 7 , wherein the electromagnetostrictive element is a Giant-magnetostrictive element.  
     
     
         13 . An actuator as claimed in  claim 8 , wherein the electromagnetostrictive element is a Giant-magnetostrictive element.