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REID VAPOR PRESSURE ESTIMATION BY MONITORING PURGE USING IAO2 SENSOR FOR EONV MONITOR ROBUSTNESS

IP.com Disclosure Number: IPCOM000244783D
Publication Date: 2016-Jan-15
Document File: 1 page(s) / 216K

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REID VAPOR PRESSURE ESTIMATION BY MONITORING PURGE USING IAO2

SENSOR FOR EONV MONITOR ROBUSTNESS

Vehicles sold in North America market are required to perform Evap leak detection. A major noise factor in the Evap leak monitor is fuel volatility. Reid vapor pressure (RVP) is the vapor pressure measured at 100 0F. The higher the RVP, the more volatile is the fuel. Present methods for detecting vapor leak (US 6283098B1 and US 20150046026A1) for EVAP monitor relies on pressure or vacuum bleed-up for diagnostics. Depending on the RVP of the fuel the pressure bleed-up could vary substantially and could result in false fail for the diagnostics. Hence, an accurate estimate of fuel RVP is desirable.

Method

Currently, PCM strategy attempts to infer some fuel characteristics such as % ethanol. However, this inference can have errors in it and only works in a combusting engine. In HEV, the inference may not be available at times due to battery run mode.

This method computes the RVP using the in-vehicle hydrocarbon measurements obtained using IAO2 sensor. Normally, an IAO2 sensor measures the air/fuel ratio. In this method, the intake manifold is instrumented with an IAO2 sensor to measure the HC concentration in the purge as shown in Fig 1.

st

concentration after refueling

The method relies on measuring the difference in hydrocarbon concentration, using IAO2 sensor, of the first purge event after refueling. The higher the RVP of a fuel, higher is the increase in HC concentr...