Use of in-cylinder pressure measurement and the response surface method for combustion feedback control in a diesel engine

Abstract

An engine control algorithm was designed and implemented on a heavy-duty diesel engine. The goal was to develop a control system that could adjust split injection parameters to accommodate changes in operating parameters such as fuel and ambient air conditions, and mechanical wear during engine operation. An in-cylinder pressure transducer was chosen for the closed-loop feedback signal to be used in conjunction with the control algorithm. The control algorithm incorporated a version of the response surface method (RSM) to adjust the fuel injection parameters and to locate the optimum settings. Optimizations of double injections at 821 r/min and 25 per cent load and 0, 15, and 30 per cent exhaust gas recirculation (EGR) were first performed using a combination of the genetic algorithm (GA) and the RSM to provide baseline cylinder pressure data and to develop control criteria. These optima were then used to calibrate the control system by providing target values for the RSM control algorithm. Tests were conducted using a heat release estimate to control heat release phasing and magnitude. The control algorithm was able to adjust the timing of the first and second injections, as well as the amount of fuel injected in each pulse to phase combustion properly.