Chevron pleated filter sheet cartridge for fluids

Claim 1

A FILTERING CARTRIDGE FOR FLUIDS CONSTITUTED BY AT LEAST ONE FILTERING SHEET FORMING A TUBULAR UNIT OF A GENERALLY CYLINDRICAL SHAPE, SAID TUBULAR UNIT HAVING A CONTINUOUS WALL WHICH IS FORMED BY RADIAL PLEATS SUPERPOSED SUBSTANTIALLY IN THE DIRECTION OF THE GEOMETRICAL AXIS OF THE CARTRIDGE AND WHICH DEFINES INSIDE THE CARTRIDGE AN EMPTY AXIAL SPACE, SAID SUPERPOSED PLEATS BEING STACKED ONE ON TOP OF THE OTHER IN NESTED RELATION SUBSTANTIALLY THROUGHOUT THE HEIGHT OF THE CARTRIDGE AND THROUGHOUT THE PERIPHERY OF SAID AXIAL SPACE AND BEING FORMED SO AS TO OBTAIN A GREATER DENSITY OF FILTERING MATERIAL ALONG THE PERIPHERY OF SAID EMPTY SPACE THAN AT ANY OTHER POINT OF THE CARTRIDGE, EACH OF SAID PLEATS BEING JOINED AT ONE OF ITS ENDS TO THE ADJACENT END OF THE NEXT ADJACENT AXIALLY DISPLACED PLEAT SO AS TO FORM A V THEREWITH, AND MEANS DEFINING A FLUID FLOW PASSAGE EXTENDING AT LEAST THROUGH ONE END OF SAID CARTRIDGE, INTO SAID EMPTY AXIAL SPACE AND TO SAID FILTERING SHEET.