REID VAPOR PRESSURE ESTIMATION BY MONITORING PURGE USING IAO2 SENSOR FOR EONV MONITOR ROBUSTNESS
Publication Date: 2016-Jan-15
The IP.com Prior Art Database
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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.
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.
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...