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This study measures, during various transients of speed and load, in-cylinder-, intake-/exhaust- (manifold) pressures and engine torque. The tests were conducted on a typical high power-density, passenger car powertrain (common-rail diesel engine, of in-line 4-cylinder configuration equipped with a Variable Geometry Turbocharger). The objective was to quantify the deterioration (relative to a steady-steady condition) in transient Specific Fuel Consumption (SFC) that may occur during lagged-boost closed-loop control and thus propose an engine control strategy that minimises the transient SFC deterioration. The results, from transient characterisation and the analysis method applied in this study, indicate that transient SFC can deteriorate up to 30% (function of load transient) and is primarily caused by excessive engine pumping-loss.

This paper describes the application of the relay auto-tuning method for the automatic calibration of the conventional EGR closed-loop controller maps in a typical Diesel engine. The paper briefly presents the theoretical background on the relay auto-tuning procedure and describes the implementation of such a procedure for the PID tuning of the EGR closed-loop system on a 4-cylinder engine with common-rail injection and variable-geometry turbocharger, for passenger car application. The relay auto-tuning method involves the implementation of the relay action in closed-loop to estimate the critical gain and critical frequency of the system, which are in turn used to estimate plant parameters for a first-order system with delay. PID controller gains are then calculated based on well-established tuning rules. The effect of the relay amplitude on the critical parameters is examined and the modifications required in the presence of noise or asymmetries in the measurements are discussed.

The study measured Mass Air Flow, (MAF), Manifold Absolute Pressure, (MAP), and emissions of NO and soot during fourteen transients of speed and load, representative of the Extra Urban Drive Cycle (EUDC). The tests were conducted on a typical passenger car/light-duty truck powertrain (a turbocharged common-rail diesel engine, of in-line 4-cylinder configuration). The objective was to compare NO and soot with corresponding steady-state emission results and propose an engine measurement methodology that will potentially quantify deviation (i.e. deterioration with respect to steady state optimum) in emissions of NO and soot during transients. Comparison between steady state, quasi-steady-states (defined later in the paper) and transients indicated that discrete quasi-steady-state engine operation, can be used for accurate prediction of transient emissions of NO and soot.