Pressure compensating vapor management valve

摘要

A fuel tank vapor management valve (VMV) for controlling purge flow from a vapor storage canister to an engine inlet manifold. In one embodiment, an existing VMV utilizing an electrically operated atmospheric bleed valve or EVR for controlling vacuum pressure on one side of the regulator valve diaphragm is modified to have an additional vacuum ported valve seat in the EVR to be opened and closed by the bleed valve instead of providing a vacuum port in the regulator diaphragm signal pressure chamber. The inlet of the EVR is connected to the storage canister instead of being ported to the atmosphere which equalizes canister pressure across the regulator diaphragm thus preventing undesired opening of the regular valve when the engine is shut off. In another embodiment, an existing VMV is unmodified, with the EVR bleed port connected to the canister and the shut-off valve is connected in the line connecting the engine manifold with the regulator valve diaphragm signal pressure chamber. The shut-off valve may be either electrically operated or pressure actuated by engine manifold vacuum.