Effect of in-cylinder pressure sensor behavior on Diesel engine performance for Closed-loop Combustion Control

This report describes the analysis, modeling and simulation of an in-cylinder pressure sensor. The final goal is to substantiate a set of minimal desired specifications for use in heavy duty Diesel engines. First the cylinder pressure sensor is divided into three subsystems. The first subsystem contains the mechanical behavior of the pressure sensor and is modeled as a transfer function. The second subsystem represents the electrical behavior while the third subsystem includes the data acquisition system. In cooperation with Sensata, a cylinder pressure sensor manufacturer a set of parameter variations is selected to simulate different sensor specifications. High resolution, real world measurement data is then used as reference and input for the model to evaluate the influence of a varying five different sensor properties: bandwidth, crank angle resolution, noise production, nonlinear behavior and analog to digital conversion quality. Using a standardized approach a total of eight Heat Release and pressure trace related combustion (control) parameters are assessed to evaluate the effects of the parameter variations: CA10, CA50, CA90, IMEP, pmax, CApmax, dp/dCAmax and CAdp/dcamax. A paired choice matrix describing the relations of these parameters on constructional and environmental engine parameters as fuel consumption and NOx are used to extract a set of desired sensor specifications. Finally this set of specifications is used in the model to compare the proposed specifications against the performance of a high-end reference sensor.