Patent ID: 8081053
Filing Date: 2011-12-20
Classification: H01F

Abstract:
1. A solenoid actuator attached to hydraulic equipment, comprising: a shaft connected to the hydraulic equipment, the shaft having a center axis; a case made of a magnetic material; a bobbin made of a non-magnetic material and having a hollow portion; a coil wound on the bobbin and housed in the case; a pressure tube made of a non-magnetic material and fitted into the hollow portion of the bobbin, the pressure tube having a first open end and a second open end; a base made of a magnetic material in a cylindrical shape and inserted into the pressure tube; a sleeve made of a magnetic material in a cylindrical shape and disposed in the pressure tube to face the base via a magnetic gap in the direction of the center axis, the case and the sleeve being magnetically connected through the first open end of the pressure tube, and the base and the sleeve forming an operation chamber on the inside thereof; and a plunger made of a magnetic material, fixed to the shaft and housed in the operation chamber while maintaining an annular gap relative to a wall of the operation chamber so as to be free to displace along the center axis, wherein the case comprises an inner cylindrical portion which projects into the pressure tube, and the sleeve is fitted onto an outer circumferential surface of the inner cylindrical portion.