Bidirectional filter

Claim 1

A BIDIRECTIONAL FILTER COMPRISING A HOUSING HAVING FIRST AND SECOND OPENINGS THEREIN OPERABLE IN FUNCTION ALTERNATIVELY AS INLETS AND OUTLETS, A FILTER ELEMENT IN SAID HOUSING HAVING AN INLET SIDE AND A DISCHARGE SIDE, FIRST AND SECOND PASSAGES CONNECTING FIRST AND SECOND OPENINGS, RESPECTIVELY, TO THE INLET SIDE OF SAID FILTER ELEMENT, THIRD AND FOURTH PASSAGES CONNECTING SAID FIRST AND SECOND OPENINGS, RESPECTIVELY, TO THE DISCHARGE SIDE OF SAID FILTER ELEMENT, A DIFFERENTIAL PRESSURE RESPONSIVE VALVE ASSEMBLY OPERABLE IN ONE POSITION TO OPEN SAID FIRST AND FOURTH PASSAGES AND CLOSE SAID SECOND AND THIRD PASSAGES, SAID VALVE ASSEMBLY HAVING FIRST AND SECOND PAIRS OF COAXIAL VALVE ELEMENTS, THE VALVE ELEMENTS OF SAID FIRST PAIR HAVING OPENINGS THERETHROUGH FORMING PARTS OF THE PASSAGES CONNECTING ONE SIDE OF SAID FILTER ELEMENT TO SAID HOUSING OPENINGS, AND A VALVE SEAT FORMED ON EACH OF THE VALVE ELEMENTS OF SAID FIRST PAIR ENGAGEABLE BY SAID SECOND PAIR VALVE ELEMENTS TO CLOSE SAID VALVE ELEMENT OPENINGS, SAID FIRST AND SECOND PAIRS OF VALVE ELEMENTS BEING AUTOMATICALLY AXIALLY SHIFTABLE IN RESPONSE TO A CHANGE IN DIRECTION OF FLOW BETWEEN SAID HOUSING OPENINGS TO CLOSE SAID FIRST AND FOURTH PASSAGE AND OPEN SAID SECOND AND THIRD PASSAGES, THE AUTOMATIC SHIFTING OF SAID VALVE ELEMENTS IN RESPONSE TO A CHANGE IN DIRECTION OF FLOW BEING OPERABLE TO CAUSE FLUID TO FLOW THROUGH SAID FILTER ELEMENT IN THE SAME DIRECTION.