Ferromagnetic/fluid valve actuator

Abstract

An actuator base ( 16 ), bobbin ( 14 ), and pole piece ( 24 ) form a pocket for an armature ( 30 ) that a flexible membrane ( 40 ) encloses to form an armature chamber filled with an incompressible fluid. The membrane ( 40 ) protects the armature ( 30 ) from exposure to corrosive fluids flowing in a conduit ( 44 ). Conduit flow can be stopped by driving the membrane ( 40 ) against a valve seat ( 54 ). Pressure from the fluid in the conduit ( 44 ) is transmitted though the membrane to the fluid within the armature chamber so that the armature does not need to counteract force applied to the membrane ( 40 ) by the conduit fluid's pressure.

1 . In an electromagnetic actuator that includes a solenoid coil and an armature housing that forms an armature pocket within which a ferromagnetic armature is disposed, the actuator being operable by driving electric current through the solenoid coil to drive the armature between retracted and extended armature positions, the improvement wherein: 
 A) the actuator further includes a flexible membrane so secured at a mouth of the pocket as to deform outward when the armature travels to its extended armature position and as further to form with the armature housing a substantially fluid-tight armature chamber that contains the armature; and    B) a substantially incompressible fluid occupies substantially the entire chamber volume not occupied by the armature.    
     
     
         2 . An actuator as defined in  claim 1  wherein the incompressible fluid includes polypropylene glycol.  
     
     
         3 . An actuator as defined in  claim 2  wherein the incompressible fluid includes potassium phosphate.  
     
     
         4 . An actuator as defined in  claim 1  wherein the incompressible fluid includes potassium phosphate.