Importance

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Abstract

An onboard refueling vapor recovery system for a motor vehicle prevents fuel vapor displaced from the vehicle fuel tank during a refueling operation from being discharged into the atmosphere and stores the fuel vapor for subsequent combustion in the vehicle engine. The system operates in parallel with a known vapor recovery system employed to minimize venting of vapor from the fuel tank through the normal fuel tank vent, this known system being inadequate to cope with the massive surge of vapor expelled during refueling which presently is vented to atmosphere through the fuel tank fill pipe. The refueling vapor recovery system includes a refueling vapor storage canister which is directly connected via a substantially unrestricted flow passage to the head space of the tank when, and only when, a standard fuel dispensing nozzle is operatively located in the fill pipe inlet. The nozzle is inserted through a seal which prevents the escape of vapor from the fill pipe. A float valve in the tank closes the passage to the refueling canister when the tank is filled and the consequent pressure increase will normally actuate the conventional nozzle shutoff mechanism. Emergency devices in the system will sound an audible signal if the nozzle shutoff malfunctions and will dump fuel from the filler pipe if manual shutoff of the nozzle does not occur in response to the audible signal. The system includes further internal pressure and flow regulating devices.

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First Claim