Optimal Feedback Control with in-Cylinder Pressure Sensor under Engine Start Conditions 2011-01-1422
In-cylinder pressure sensor, which provides the means for precise combustion control to achieve improved fuel economy, lower emissions, higher comfort, additional diagnostic functions etc., is becoming a necessity in future diesel engines, especially for chemical-kinetics dominated PCCI (Premixed Charge Compression Ignition) or LTC (Low Temperature Combustion) engines. In this paper, new control strategy is investigated to utilize in-cylinder pressure information into engine start process, in order to guarantee the success of engine start and in the meantime prevent penalty of fuel economy or pollutant emissions due to excessive fuel injection.
An engine start acceleration model is established to analyze the engine start process. “In-cylinder Combustion Analysis Tool” (i-CAT), is used to acquire and process the in-cylinder pressure data and deliver the combustion indices to ECU (Engine Control Unit). Feedback control is accomplished in ECU based on this information. The engine start performance is verified and analyzed by engine bench tests. By using feedback control, engine speed overshooting and unnecessary fuel consumption can be avoided during the starting process. Result shows feedback control can guarantee adequate fuel injection to overcome the frictional force and assure the desired engine speed profile during the cranking condition, without the effort of elaborate calibration.