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A DIAGNOSTIC FOR A LATCHABLE REFUELING VALVE IN PHEV VEHICLES

IP.com Disclosure Number: IPCOM000243425D
Publication Date: 2015-Sep-21
Document File: 1 page(s) / 221K

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The IP.com Prior Art Database

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A DIAGNOSTIC FOR A LATCHABLE REFUELING VALVE IN PHEV VEHICLES

PHEV vehicles have a sealed fuel tank, due to limited engine run time which constrains cleaning the canister. A PHEV vehicle uses a Non Integrated Refueling Canister Only System (NIRCOS).Vapors from running loss and diurnal temperature cycles must be contained inside the sealed the fuel tank. The NIRCOS canister adsorbs refueling vapors only; hence it is a smaller sized canister. A Fuel tank isolation valve (FTIV) is normally closed and the fuel tank is made of heavy steel to withstand the pressure and vacuum builds from diurnal temperature cycle inside the tank. The FTIV draws considerable current when energized. Some systems may use an energy efficient latchable valve instead. A latchable valve closes when pulsed with a 100ms voltage and opens when pulsed again. Since the valve is pulsed to an open state and pulsed to a closed state, the control module (PCM) must keep track of valve position in memory.Should the battery go low, the valve position information could be invalid, and the PCM may need re-flashing, memory corruption, or actual valve replacement. Lack of knowledge in the valve position could potentially leave the NIRCOS system in an undesirable open state and emissions would be impacted as the canister would have been loaded from diurnal and running loss vapors. A common method to infer valve position is observing pressure/vacuum generation from diurnal temperature cycle.

Method

This method infers the valve pos...