Self-cleaning filter device

Claim 1

A FILTER DEVICE FOR A FLUID SYSTEM, SAID FILTER DEVICE COMPRISING, (A) A HOUSING HAVING AN INLET AND AN OUTLET, (B) A FILTERING ELEMENT CARRIED IN SAID HOUSING INTERMEDIATE SAID INLET AND SAID OUTLET, (C) MEANS OPERABLE TO VARY THE POROSITY OF SAID FILTER ELEMENT, (D) PRESSURE RESPONSIVE MEANS OPERABLE TO ACTUATE SAID LAST MENTIONED MEANS TO INCREASE THE POROSITY OF SAID FILTERING ELEMENT UPON A PREDETERMINED INCREASE IN THE PRESSURE DIFFERENTIAL ACROSS SAID FILTERING ELEMENT, (E) SAID FILTERING ELEMENT COMPRISING A POROUS CONTAINER CARRIED IN SAID HOUSING AND A PLURALITY OF FILTERING PARTICLES CARRIED IN SAID CONTAINER, AND (F) SAID POROSITY VARYING MEANS COMPRISING A WALL MEMBER CARRIED IN SAID CONTAINER AND ENGAGING SAID FILTERING PARTICLES, MEANS NORMALLY URGING SAID WALL MEMBER AGAINST SOME OF SAID FILTERING PARTICLES TO IMPART COMPRESSION THERETO, AND MEANS ACTUATED BY SAID PRESSURE RESPONSIVE MEANS TO MOVE SAID WALL MEMBER AWAY FROM SAID FILTERING PARTICLES UPON A PREDETERMINED INCREASE IN THE PRESSURE DIFFERENTIAL ACROSS SAID FILTERING ELEMENT.