Leaf valve

A leaf valve is a one-way valve (check valve) consisting of a diagonal obstruction with an opening covered by a hinged flap.
Patents exist in the United States which specify the mechanical use of leaf valves to control various types of fluids.
United States Patent 4930535 is a folding leaf valve which is described as a valve that, "folds upon itself to provide positive sealing of a pressurized chamber under a variety of pressure conditions. In particular, the valve stem folds to effectively close the lumen and provide a positive seal even at low differential pressure."
United States Patent 4795340 is a single leaf valve for a gas-fired boiler. It has a seat for a valve leaf, and a single valve leaf for the two constituents, this single valve leaf being flexible and deformable... Application, in particular, to gas-fired boilers of the pulsed-combustion type."
United States Patent 5441133 – This hydraulic damper has a leaf valve stopper, the patented invention relates to a hydraulic damper. A leaf valve and a main valve are provided at an inner seat and an outer seat having different heights to each other arranged at outlet ports of a piston in such a way as they may be opened or closed... an attenuation force can be stabilized.. and the leaf valve is supported by the tapered or curved surface of the stopper when flexed, resulting in that no cracks are generated.