Electromagnetic locking type actuator

An electromagnetic locking type actuator, comprising:

• a body having a fluid passage therethrough;
• a control member reciprocatable in said body for controlling the fluid pressure in said passage;
• an electromagnetic means positioned on said body for applying a first magnetomotive force to said control member, said electromagnetic means having an inner yoke, an outer yoke including a flange portion around said inner yoke, an electromagnetic coil between said inner and outer yokes, and means for directing an energizing current through said coil in one direction and in a second direction which is the opposite of said one direction;
• and
• a permanent magnet means positioned adjacent to and separated from said electromagnetic coil by said flange portion of the outer yoke for directing flux to said yokes for applying a second magnetomotive force in one direction to said control member at all times, said electromagnetic means, when an electric current in one direction is applied thereto, generating a first magnetomotive force in the said one direction for moving said control member toward said permanent magnet means and said electromagnetic means to a movement terminating position, and said permanent magnet means holding said control member at said movement terminating position after said first magnetomotive force no longer acts after the electric current is discontinued, and when an electric current in a direction opposite said one direction is applied thereto, generating a first magnetomotive force cancelling out said second magnetomotive force, whereby said control member is released from the effect of magnetomotive forces;
• said electromagnetic means having a magnetic gap between said inner yoke and said flange portion of the outer yoke for preventing the flux of said permanent magnet means from leaking directly to said inner yoke from said flange portion of the outer yoke.