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A STUCK OPEN FLVV DIAGNOSTIC AND MITIGATION FOR GASOLINE VEHICLES

IP.com Disclosure Number: IPCOM000237701D
Publication Date: 2014-Jul-03
Document File: 1 page(s) / 235K

Publishing Venue

The IP.com Prior Art Database

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A STUCK OPEN FLVV DIAGNOSTIC AND MITIGATION FOR GASOLINE VEHICLES

Vehicles sold in North America market typically have a fill limit float valve inside the tank. The FLVV is the Fill Limit Venting Valve. During refueling, it is the passage way for fuel vapors to enter the canister where the vapors are adsorbed.As the fuel level reaches 100% of tank capacity, liquid fuel displaces the spring loaded FLVV and causes it to shut closed. Once the FLVV closes, a dramatic pressure rise develops inside the fuel tank. This pressure rise causes the refueling dispense nozzle to shut off liquid fuel. Pump shutoff occurs when the dispensing nozzle sees a 12 InH2O back pressure at the nozzle. If FLVV is stuck closed, operator will not be able to refuel the tank easily and premature shutoffs occur. If FLVV is stuck open, operator will be able to refuel. However, the pressure rise will not develop when the fuel level reaches 100% and dispensing pump will continue delivering fuel until fuel overflows (fuel spitback).This failure mode is highly undesirable as fuel may spill outside the vehicle.

Method

The invention centers around developing a diagnostic for a stuck open FLVV and performing mitigation action to prevent liquid fuel overflow and spillage. A stuck open FLVV is typically characterized by fuel level saturating at 100% but tank pressure as measured by the FTPT sensor staying steady(> 0.5 and

0.5 Inh2O is needed to allow liquid to fill the vapor dome. After the time delay...