Position sensor for latching solenoid valve

Abstract

The invention is directed to an improved position sensor for a latching solenoid ( ). In the preferred embodiment, the solenoid has a permanent magnet ( ), a coil ( ) adapted to be selectively energized by either a positive or negative current, a first pole-piece ( ) and a second pole-piece ( ), a first armature ( ) positioned between the pole pieces, a first air-gap ( ) and a second air-gap ( ) between the armature and the first and second pole pieces, respectively, and a first magnetic flux path ( ) and second magnetic flux path ( ) associated with the first and second pole pieces, respectively, the armature being movable between an alternate first position ( ) and second position ( ) wherein flux from the magnet will hold the armature in either of the positions, the armature, magnet and air-gaps being so configured and arranged that selective energization of the coil produces a coil flux to cause the armature to move to and latch in one of the positions. The improvement comprises an indicator pole piece ( ), an indicator armature ( ) being movable between a first indicator position ( ) and a second indicator position ( ), an indicator air-gap ( ) between the indicator pole piece and the indicator armature, the indicator pole piece, armature, and air-gap being arranged in only one of the flux paths such that the magnet flux in the flux path influences the indicator armature, whereby the position of the indicator armature provides an indication of the position of the first armature.