Closed-loop control of start of combustion using difference pressure management

Abstract

Abstract

A great deal of attention is being paid to the common-rail direct injection (CRDI) diesel engine as a promising technology for enhancing engine performance and satisfying stringent emission regulations. In a conventional CRDI diesel engine, the start of combustion (SOC) is controlled in an open-loop manner by adjusting the start of energizing (SOE) of an injector. The open-loop SOC control cannot compensate for unexpected variations in the injection delay and ignition delay resulting from cycle-by-cycle variation, cylinder-to-cylinder variation, production variation, and ageing. In this study, cylinder pressure was investigated as a means for controlling the SOC of a CRDI diesel engine. Various pressure variables were compared for the purpose of detecting the SOC of a CRDI diesel engine. The crank angle position at which the difference pressure becomes 10 bar (CA_DP10) was selected as the pressure variable for the detection of the SOC. The control performance was evaluated with engine-dynamometer experiments in steady and transient operating conditions. The experimental results showed that difference pressure managing can be effectively used for real-time detection of the SOC. Furthermore, the SOC detection technique enables the fuel control strategy to be transformed from an open-loop scheme to a closed-loop scheme.