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METHOD TO LOWER FUEL RVP IN SADDLE SHAPED FUEL TANKS

IP.com Disclosure Number: IPCOM000247924D
Publication Date: 2016-Oct-11
Document File: 1 page(s) / 198K

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The IP.com Prior Art Database

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METHOD TO LOWER FUEL RVP IN SADDLE SHAPED FUEL TANKS

Most All Wheel Drive (AWD) vehicles have two fuel tanks that are connected to each other at the top due to packaging constraints around the AWD gear differential unit and shaft. These are called saddle tanks.Saddle tanks are typically positioned east-west in the rear of a car with one tank on driver side and the other on passenger side. The active side has a fuel pump and a Fuel Level Indication ("FLI1"). The passive side (without an active pump) has another Fuel Level Indication ("FLI2"). The active side is maintained full of fuel as a jet pump driven off the main electric fuel pump siphons fuel from the passive side to the active side. In non HEV saddle tanks, FLI1 >> FLI2, since the jet pump always seeks to keep the active tank full. In HEVs, the fuel may linger inside the fuel tank for months if customers drive in electric mode. If customer refuels a vehicle in the winter months with high volatility Reid Vapor Pressure (RVP) fuel and Evap diagnostic executes in the summer months, the Evap diagnostic monitor may experience robustness issues from false failures due to the natural high vaporization of the winter fuel. Summer fuel is typically low RVP to reduce hydrocarbon emissions and winter fuel is high RVP to improve vehicle cold starting quality. Ideally, vehicles should not have high RVP fuel in the summer.

Method

Our new method keeps track of the last refueling event in the PCM and infers the fuel RVP either onboard via Hydrocarbon sensor or by correlation to a real time calendar and GPS.If the fuel is determined to be high RVP and the season has changed from cold to warm bas...