Filter unit and filter cartridge therefor

Claim 1

A FILTER UNIT COMPRISING IN COMBINATION: A CORE IN THE FORM OF A RIGID TUBULAR MEMBER ADAPTED TO ACCOMMODATE FLUID THERETHROUGH; AT LEAST ONE PAIR OF MUTUALLY OVERLYING FILTER ELEMENT SHEETS IN THE FORM OF A STRIP OF FINE MESH STAINLESS STEEL WIRE FILTER MATERIAL REELED UPON ITSELF ON SAID CORE; WEB MEANS OF COARSE MESH MATERIAL BETWEEN SAID PAIR AND ALL OVERLYING SURFACES OF SAID STRIP SEPARATING AND SUPPORTING THE SAME REELED UPON ITSELF ON SAID CORE AND ADAPTED TO COMMUNICATE FLUID THERETHROUGH BETWEEN SAID SHEETS; A SEALING STRIP WELDED ON A DIFFERENT EDGE ON EACH SHEET AND TO AN UNDERLYING EDGE OF AN ADJACENT SHEET EDGE SURFACE THROUGHOUT THE LENGTH THEREOF WHEN REELED ON SAID CORE AND PREVENTING PASSAGE OF LIQUID THEREBETWEEN; SEALING RINGS EXTENDING AROUND SAID REELED STRIPS AT EACH END THEREOF; A ONE-WAY VALVE MEMBER IN SAID TUBULAR CORE; A RIGID TUBULAR CASE EXTENDING ABOUT AND CONTACTING THE EXTERIOR OF SAID REELED SHEETS TO DEFINE WITH THE LATTER AND SAID CORE A RIGID FILTER CARTRIDGE AND EXTENDING BEYOND EITHER END THEREOF; FIRST AND SECOND CUP-SHAPED END FITTINGS FOR SAID CARTRIDGE FITTING WITHIN SAID ENDWISE EXTENSIONS OF SAID TUBULAR CASE AND CONTACTING OPPOSITE ENDS OF SAID ROLLED FILTER ELEMENT SHEETS AND DEFINING WITH SAID CARTRIDGE RESPECTIVE FLUID CHAMBERS COMMUNICATING WITH SAID CORE AND THE EDGES OF SAID REELED SHEETS AT BOTH ENDS THEREOF AND ABUTTING THE RESPECTIVE ENDS THEREOF; RETAINING MEANS THREADEDLY ENGAGING SAID CASING AND MAINTAINING SAID END FITTINGS IN POSITION WITHIN SAID ENDWISE EXTENSIONS OF SAID TUBULAR CASING AND PREVENTING MOVEMENT OF SAID ROLLED FILTER ELEMENT SHEETS; AN INLET PORT LOCATED IN SAID FIRST END FITTING ALONG THE CENTRAL AXIS THEREOF, AND AN OUTLET PORT LOCATED IN SAID SECOND END FITTING ALONG THE CENTRAL AXIS THEREOF AND CO-AXIAL WITH SAID INLET PORT AND DEFINING AN AXIAL FLOW PATH FOR FLUID.