Pressure differential bypass sensor switch

Claim 1

A pressure differential sensor switch for use in a fluid circulating system, said pressure differential sensor switch being adapted to perform an electrical switching function when an excessive pressure differential develops between a high fluid pressure location in the system and a low fluid pressure location in the system, said pressure differential sensor switch comprising: a housing having a first passage with a central axis and a second passage, with a central axis said first passage having a first opening that is exposed to said high fluid pressure location and a second opening that is exposed to said low fluid pressure location, said central axis of said second passage being disposed in a non-parallel orientation with respect to said central axis of said first passage; a reciprocable piston located in said first passage of said housing and reciprocable therein, said reciprocable piston being reciprocable in said first passage of said housing between a first piston location adjacent said first opening and a second piston location adjacent said second opening, said reciprocable piston having a first side that is exposed to the pressure at said high fluid pressure location through said first opening and a second side that is exposed to the pressure at said low fluid pressure location through said second opening; biasing means located in said first passage of said housing and resiliently biasing said reciprocable piston toward said first piston location, the force exerted by said biasing means being sufficient to maintain said reciprocable piston at said first piston location when the differential in pressure between said pressure at said high fluid pressure location and said pressure at said low fluid pressure location is below a predetermined differential in pressure, the force exerted by said biasing means also being insufficient to maintain said piston at said first piston location when said differential in pressure exceeds said predetermined differential in pressure, whereby said reciprocable piston will move to said second piston location when said differential in pressure exceeds said predetermined differential in pressure; a permanent magnet carried by said reciprocable piston and reciprocable therewith; and an axial travel electrical switch located in said second passage of said housing, said axial travel electrical switch having a switching element that is movable only along said central axis of said second passage between a first position and a second position, one of said first position and said second position being a switch opened position and the other of said first position and said second position being a switch closed position, said switching element of said axial travel electrical switch being responsive to magnetic forces and being adapted to be moved by magnetic force from one of said first position and said second position to the other of said first position and said second position, said second passage being positioned relative to said first passage such that said permanent magnet acts magnetically on said switching element of said axial travel electrical switch to move said switching element of said axial travel electrical switch from said one of said first position and said second position to the other of said first position and said second position when said reciprocable piston moves in said first passage from said first piston location to said second piston location to move said permanent magnet that is carried by said reciprocable piston.