Pressure relief valve and method of manufacturing the same

Abstract

A flap-type pressure relief valve for venting of pressure out of, for example, an automobile passenger compartment has a flap assembly manufactured by a co-molding operation and inserted into a valve housing to block the flow of air therethrough. The valve flap assembly includes a flap carrier frame formed from a relatively rigid plastic in the first shot of a two-shot co-molding process, and at least one flap formed from a relatively flexible plastic in the second shot. The co-molding joins the flap to a first perimeter wall of the frame along an edge of the flap, and the flap is sufficiently flexible to bend about a line adjacent the edge. In a two flap version, a second flap co-molded into connection with a second perimeter wall of the frame. The resulting flap assembly can be easily connected with the separately-molded valve housing by securing the frame to the housing such that the flaps are positioned over valve seat within the housing. The flaps are co-molded into connection with the frame such that when the frame is secured to the housing to position the flaps over the air passages, the flaps are bent away from the as-molded configurations, thereby generating elastic force urging the flaps toward the respective valve seats. The flaps can have rigid plastic stiffeners co-molded into connection therewith. The stiffeners are preferably formed simultaneously with the frame in the first shot of the co-molding process.