VAPOR RECOVERY SYSTEM WITH TWO STAGE VALVE

摘要

An onboard vapor recovery system for a vehicle fuel system having a fuel tan k (10), a filler neck (12) dynamically sealed by high pressure fuel flow from a filler nozzle, and a vapor recovery apparatus such as a carbon canister (18) . The system includes a liquid level operated control valve (20) which shuts o ff refueling with a two-stage closing operation providing an initial soft shuto ff and a final shutoff. The system also includes head valve means (22) in the fuel tank to maintain a predetermined pressure head sufficient to hold the system closed against further refueling at least temporarily, and a positive action, one-way check valve (24) in the lower end of the filler pipe (12) to prevent spitback of fuel from the pressurized tank (10) once refueling has ceased.