Patent ID: 6877381
Filing Date: 2005-04-12
Classification: F02M

Abstract:
1. A differential pressure signaling device comprising a casing divided by a movable wall to provide respective chamber spaces on opposite sides of the wall, a first sensing port for communicating a first pressure to a first of the chamber spaces and a second sensing port for communicating a second pressure to a second of the chamber spaces, and a signaling mechanism for signaling change in differential pressure between the two chamber spaces comprising a first magnet disposed on the movable wall for movement therewith, a second magnet fixedly disposed within one of the chamber spaces and poled in magnetic opposition to the first magnet to oppose motion of the first magnet toward the second magnet, and a magnetoresistive sensor arranged relative to the magnets such that movement of the wall that occurs in consequence of change in pressure differential between the chamber spaces changes the magnetic flux acting on the magnetoresistive sensor, including a third magnet fixedly disposed on the casing end wall that bounds the end of the other chamber space.