Abstract: A method and apparatus for overmolding a plastic shroud onto a bobbin including the step of providing a protrusion ring on the surface of the bobbin surrounding each standoff between the bobbin and a mold wall and extending outwards from the surface of the bobbin. A plurality of standoffs and protrusion rings is presently preferred. The protrusion rings are small relative to the standoffs, have low thermal mass, and thus are readily melted by the injected molten plastic, causing interstitching between the bobbin material and the overmolding material. The interstitching creates a highly effective hermetic seal against moisture leakage along the surface of the bobbin away from the standoff site. Perfect melting of the standoffs is no longer required, and standoffs can be designed to assure proper positioning of the bobbin during the complete overmolding process.

Abstract: A method and apparatus for overmolding a plastic shroud onto a bobbin including the step of providing a protrusion ring on the surface of the bobbin surrounding each standoff between the bobbin and a mold wall and extending outwards from the surface of the bobbin. A plurality of standoffs and protrusion rings is presently preferred. The protrusion rings are small relative to the standoffs, have low thermal mass, and thus are readily melted by the injected molten plastic, causing interstitching between the bobbin material and the overmolding material. The interstitching creates a highly effective hermetic seal against moisture leakage along the surface of the bobbin away from the standoff site. Perfect melting of the standoffs is no longer required, and standoffs can be designed to assure proper positioning of the bobbin during the complete overmolding process.

Abstract: A thermoplastic carrier sheet is die-cut to have a size and shape matching that of a PEM bipolar plate. A plurality of holes are punched in the carrier sheet in the pattern of gasket beading to be formed subsequently. In a mold, liquid gasket resin fills the mold on both sides of the carrier sheet to form the gasket, flowing through the holes in the sheet and thereby causing the gasket to become mechanically attached to the sheet. A carrier element having a flange portion substantially identical with the outer profile of the bipolar plates is laminated to the sheet edge. During assembly of a fuel cell, the carrier element automatically positions the gasket correctly on the plate and prevents the gasket from twisting or shifting. In a currently preferred embodiment, a membrane electrode assembly is attached within an appropriate opening in the carrier sheet.

Abstract: A shaft for receiving a polymer overmolding of a gear from an axial single-gate mold. The shaft is provided with a plurality of features for preventing rotation of the molded gear on the shaft, the features being in the form of axial-direction flats, the number of such flats being greater than the prior art two (double D) and preferably four (quadral D). In a four-flat mold and shaft arrangement having a single, axial mold gate, longitudinal knit lines between the quadral D's are virtually non-existent, and polymer in these regions is substantially as strong as polymer elsewhere in the casting.

Abstract: A short-stroke solenoid-actuated valve suitable for pulsewidth modulated operation including a plurality of components formed of powdered metal, preferably a 400-series stainless steel compressed to about 6.0 g/cm3, to be sound absorptive and ferromagnetic; resilient radial seal means disposed in an annular groove in an outer surface of the valve for sealing against a cylindrical receiving surface; metal mesh shaft seal means for inhibiting leakage from the valve into the actuator; and a dielectric polymeric encapsulant loaded with a thermally conductive particulate substance to increase the heat-transfer modulus of the encapsulant.