Thomas L Frederick

US Patent:

52440028, Sep 14, 1993

Filed:

Dec 18, 1991

Appl. No.:

7/809931

Inventors:

Thomas R. Frederick - Amherst NY

Assignee:

Moog Controls, Inc. - East Aurora NY

International Classification:

F15B 13043

US Classification:

137 1

Abstract:

An electro hydraulic servo valve has a pair of oppositely polarized magnets mounted in the surface of the spool of the valve to be controlled. A Hall effect sensor is mounted in the housing adjacent the magnets to precisely measure the position of the spool relative to the housing. The magnets and transducer are mounted on the longitudinal centerline of the spool to eliminate the spurious signals, due to temperature, vibrations, shock, hydraulic supply pressure and back pressure. The strength and spacing of the magnets and air gap are chosen to provide a linear output signal over the range of displacement desired and to provide the accuracy of location necessary for the particular configuration.