Warren P. Williamson

Pivot pin bearing/seal with loose eyelet especially suited for disposable continuous flow blood filtration system cartridges

A pivot pin bearing/seal especially adapted for supporting the rotor of a disposable filtration cartridge of a continuous-flow plasmapheresis blood separation system includes a lubricious plastic pivot pin injection molded with a recess at its end. The recess is surrounded by a sharp circular inside edge. A stainless steel eyelet, deep drawn from successive dies, is loosely inserted into the pin recess, a radial outer surface defined at the junction between the eyelet shank and the eyelet flange contacting the pin sharp edge. The eyelet rotates relative to the pin, the circular line path of rotational contact being defined by the smooth curved surface under the flange of the eyelet and the sharp inside edge surrounding the pin recess which quickly burnishes to a good rotational seal. A silicon elastomer seal ring is disposed between the eyelet flange and the rotating filtration rotor to establish a fluid-tight essentially non-rotating seal between the eyelet and the rotor (and therefore causing the eyelet to rotate with the rotor relative to the pin). Coaxial sealing structures may be provided in cascade-type filter cartridges.