Filter mfr. with folded paper element - for filtration of and removal of water from fuel etc.

摘要

Mfr. of a filter box comprising a cylindrical outer housing and a concentric inner pipe with a folded bellows-type filter element of paper occupying the annular space between the housing and the inner pipe. The filter element is formed by zig-zag folding of a strip of paper, and when in position, the fold-edges extend radially outwards from the inner pipe to the housing whilst the zig-zag edges of the paper lie on the inner and outer cylindrical surfaces. The medium to be filtered flows in the axial direction through the element. In the procedure claimed, the folded paper is first extended to a length equal to the circumference of the inner cylindrical shape it later assumes. The bellows is then firmly fixed to a strip of material (which will later form the inner pipe) which lies along one of the sides on which the zig-zag edges are exposed. The end of the material extends past the end of the filter to act later as an overlap joint. The bellows is then bent into the required annular cylindrical shape and the ends of the strip of filter paper are joined together. with the inner sealing strip overlap edge still unfastened, the element is inserted into the housing using a jointing material. Pressure is finally applied from inside the central pipe to firmly seal the outer cylindrical surfaces to the housing and to seal the inner overlap joint. Provides ease of production, and reliable seal formation.