Filter cartridge end cap assembly

Claim 1

An end cap assembly for a filter cartridge including a tubular filter element comprising: an end cap having an inner surface, an outer surface, an outer circumference connecting said inner and said outer surfaces and having dimensions such that the inner surface of said filter element may be drawn over said circumference, and a projection coextensive with said circumference and extending beyond said outer surface, said projection having a small volume relative to said end cap volume; a lock ring having an inner surface, an outer surface, an inner circumferential surface connecting said inner and said outer surfaces and sized to capture said filter element between said lock ring inner circumferential surface and said end cap outer circumference and a projection coextensive with said lock ring inner circumferential surface and having a small volume relative to said lock ring volume and extending beyond said lock ring outer surface a distance substantially equal to the extension of said end cap projection so that, when said end cap and said lock ring are assembled to capture said filter element, and with said end cap outer surface and said lock ring outer surface aligned, said end cap projection and said lock ring projection extend substantially equally from said end cap and said lock ring outer surfaces and capture said filter element therebetween; said projections being supplied so that heat may be applied to said projections after assembly of said lock ring to said end cap to fuse said lock ring to said end cap to provide a leak-proof seal therebetween.