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METHOD TO INFER VEHICLE FUEL RVP

IP.com Disclosure Number: IPCOM000244487D
Publication Date: 2015-Dec-16
Document File: 1 page(s) / 230K

Publishing Venue

The IP.com Prior Art Database

Abstract

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METHOD TO INFER VEHICLE FUEL RVP

Vehicles sold in North America are required to perform Evap leak detection as part of OBDII requirements. Green states required to monitor for 0.02" leaks as part of the Clean Air Act Section 177. (CAA).For PHEV, engine run time is limited hence a vacuum pump is required to perform Evap leak detection. One such vacuum pump is the ELCM system.ELCM test sequence begins with obtaining a "reference check" by turning on its vacuum pump and evacuating small volume where internal 0.02" reference orifice is located. The reference vacuum value obtained becomes pass/fail threshold. The internal reference orifice compensates for prevailing environmental factors such as temperature, altitude and humidity. By having an internal reference orifice, the leak detection becomes self- calibrating and there is no need to store 3D maps in the PCM to compensate for temperature, humidity, altitude, fuel level.One noise factor that the ELCM does not compensate for is fuel volatility (RVP). Fuel is isolated from the ELCM in a PHEV via the closed FTIV valve. If highly vaporous fuel (i.e., winter fuel) is present in the fuel tank, the high vapor content would counteract the vacuum pull of the ELCM pump and the result would be false monitor results.

Method

As fuel is evacuated from a fuel tank when the fuel tank is vented to atmosphere, the partial pressures equilibrium in the vapor dome between is disturbed. When the system is sealed again after a known...