VARIABLE RELUCTANCE POSITION SENSOR

摘要

A position sensor (10) is disclosed having a transducer (14) formed by a Hall-effect device (24) and permanent magnet (22) secured within a housing (20) on either side of a low permeability gap (26). A target (12) secured to an active member (16), such as an EGR valve plunger moves within the gap (26). The target (12) has a flux modulating property that varies with position along a direction of travel (18). Variable reluctance is achieved in some embodiments by varying the cross section of the target (12) with position. In some embodiments, a second target (12b) having substantially constant reluctance secures to the active member (16) and moves within a gap (26) defined by a second transducer. The output of the second transducer (14b) is used to normalize the output of the first transducer (14a) and compensate for anomalies such as drift and movement other than in the direction of travel (18) of the active member (16).