Automotive cold start fuel volatility compensation
First Claim
1. An internal combustion engine air/fuel ratio control method, comprising the steps of:
- sensing an engine startup operation;
sampling an input signal indicating engine speed following the engine startup operation;
estimating fuel volatility as a function of engine speed;
identifying the estimated fuel volatility as one of a high volatility and a low volatility;
modifying a correction value, by (a) increasing the correction value upon identifying the estimated fuel volatility as a low volatility, and (b) decreasing the correction value upon identifying the estimated fuel volatility as a high volatility;
correcting an air/fuel ratio control command as a function of the modified correction value; and
controlling engine air/fuel ratio in accordance with the corrected air/fuel ratio control command to provide for accurate engine air/fuel ratio control over a range of fuel volatilities.
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Abstract
Automotive internal combustion engine fuel volatility is estimated during cold start operations by stabilizing air admission to the engine and analyzing engine speed over a modeling period following an engine coldstart after engine speed has stabilized and prior to closed-loop engine operation. If engine speed deviates significantly away from an expected engine speed for the current engine intake air and fuel, a fuel volatility deviation is diagnosed. The magnitude of the fuel volatility deviation away from a nominal fuel volatility is determined as a function of the magnitude of the engine speed deviation. A fuel volatility correction value is updated as a function of the engine speed deviation and is applied throughout an ignition cycle, including during the modeling period to compensate for the fuel volatility deviation.
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Citations
5 Claims
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1. An internal combustion engine air/fuel ratio control method, comprising the steps of:
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sensing an engine startup operation; sampling an input signal indicating engine speed following the engine startup operation; estimating fuel volatility as a function of engine speed; identifying the estimated fuel volatility as one of a high volatility and a low volatility; modifying a correction value, by (a) increasing the correction value upon identifying the estimated fuel volatility as a low volatility, and (b) decreasing the correction value upon identifying the estimated fuel volatility as a high volatility; correcting an air/fuel ratio control command as a function of the modified correction value; and controlling engine air/fuel ratio in accordance with the corrected air/fuel ratio control command to provide for accurate engine air/fuel ratio control over a range of fuel volatilities. - View Dependent Claims (2, 3, 4, 5)
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Specification