Radiator pressure cap

Claim 1

In a radiator closure cap for cooperation with the radiator filler neck of a closed fluid cooling system, the cap comprising an outer circular closure member having lugs for attachment to the filler neck, a metal disc sealing member attached to the inner surface of said circular closure member and a gasket member adjacent the outer edge of said disc member that together provide a nonreleasing seal between said radiator cap and the upper rim of the filler neck upon securing said cap thereon, a center post member attached to the inner surface of said circular closure member, a generally circular cup shaped body member open at one end surrounding said center post and secured at its closed end to the said circular closure member by said center post, a plurality of openings in the side of said cup shaped member to interconnect the filler neck with the inside of the cup shaped member, an annular flexible fluid tight diaphragm secured at its outer edge to the open end of said cup shaped body member in fluid tight relationship therewith and being adapted to form a nonreleasing seal between said cup shaped member and a sealing surface formed on the lower part of the filler neck, the inner edge of said annular diaphragm being spaced apart from the surface of said center post to provide a fluid passage therebetween to permit movement of fluids between the radiator side of said annular diaphragm and the opposite side thereof, a relief valve mounted on said center post and seating on said radiator side of said annular diaphragm to seal said fluid passage, a relatively light spring urging said relief valve into sealing contact with said annular diaphragm to seal said fluid passage, a relatively heavy spring urging said annular diaphragm toward the radiator, and means on said center post to limit the movement of said relief valve as it follows the movement of said annular diaphragm away from the radiator toward said closure cap whereby excessive pressure in the radiator moves the annular diaphragm against the force of said heavy spring opening said relief valve to vent pressure from the radiator to the filler neck through the openings in said cup shaped body member when said relief valve is stopped by said limit means, vacuum in said radiator being equalized by the movement of said relief valve against said light spring force and away from said diaphragm.