Filter unit having dual purpose valve assembly

Claim 1

AN OIL FILTER COMPRISING A CASING WITH AN INLET AND A CENTRAL OUTLET, SAID INLET BEING DISPOSED OUTWARDLY OF SAID OUTLET, AN ANNULAR TUBULAR FILTER SUPPORT MEMBER SURROUNDING SAID OUTLET, A FLANGE ON SAID MEMBER, AN ANNULAR FILTER ELEMENT SEATED ON SAID FLANGE, AN ANNULAR VALVE MEMBER SLIDABLY DISPOSED ON SAID TUBULAR SUPPORT MEMBER, PORT MEANS IN SAID TUBULAR MEMBER FOR COMMUNICATING SAID INLET WITH SAID OUTLET, SAID VALVE MEMBER EMBODYING A VALVE DISC PORTION FOR SEATING OVER SAID INLET AND ANOTHER PORTION FOR CLOSING OFF SAID PORT MEANS AND BLOCKING THE LATTER AND SAID INLET, BIASING MEANS MAINTAINING SAID DISC PORTION SEATED OVER SAID INLET WHEN OIL CEASES TO FLOW THROUGH SAID INLET, SAID DISC PORTION BEING DISPOSED TO PERMIT THE PRESSURE OF OIL ENTERING SAID INLET TO ACT AGAINST ITS TOTAL AREA TO UNSEAT IT A SUFFICIENT DISTANCE DURING NORMAL OPERATION OF THE FILTER ELEMENT WHILE MAINTAINING SAID OTHER PORTION SEATED OVER SAID PORT MEANS, AND DISPOSED TO PERMIT A SUBSTANTIALLY HIGHER OIL PRESSURE TO ACT AGAINST A REDUCED AREA OF SAID DISC PORTION WHEN THE FILTER IS CLOGGED TO MOVE SAID DISC PORTION AWAY FROM SAID INLET A FURTHER DISTACNE TO UNCOVER SAID PORT MEANS TO PERMIT OIL TO SHORT CIRCUIT SAID FILTER ELEMENT.