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BOOSTED PASSIVE PURGE EVAP METHOD FOR NIRCOS VEHICLES

IP.com Disclosure Number: IPCOM000244359D
Publication Date: 2015-Dec-04
Document File: 1 page(s) / 266K

Publishing Venue

The IP.com Prior Art Database

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BOOSTED PASSIVE PURGE EVAP METHOD FOR NIRCOS VEHICLES

PHEV vehicles have a sealed fuel tank called NIRCOS (Non Integrated Refueling Canister Only System). The steel tanks can withstand +/- 5 PSI of pressure/vacuum. FTIV valve is normally closed valve that seals the fuel tank. NIRCOS tank is made of heavy steel to withstand pressures and vacuum builds from the diurnal temperature cycle.The fuel tanks are sealed due to limited engine run time which impacts canister cleaning. Since the NIRCOS tank is sealed, it almost always holds pressure or vacuum inside it. During the daylight hours, sun loading warms up the bulk liquid fuel and generates pressure inside the tank. During the night hours, the liquid fuel cools and vacuum is generated inside the fuel tank. The cooling effect causes passive purge to occur. Passive purge is able to clean out 40-50% of the canister. In most geographical areas, diurnal temperature cycles typically yield more pressure than vacuum inside fuel tanks due to the daylight hours being more than the night hours. However, the pressure energy inside the fuel tank is not typically used since if fuel tank pressure is released by opening FTIV, canister loading results which is not desirable. The pressure energy inside a NIRCOS tank is hence wasted.

Method

This method performs a "boosted" passive purge actively in vehicles with NIRCOS tanks. The pressure inside the fuel tank is used to "pump in" fresh air into the sealed canister. A bladder type "...