Robust cylinder pressure estimation in heavy-duty diesel engines

Abstract

The robustness of a new single-cylinder pressure sensor concept is experimentally demonstrated on a six-cylinder heavy-duty diesel engine. Using a single-cylinder pressure sensor and a crank angle sensor, this single-cylinder pressure sensor concept estimates the in-cylinder pressure traces in the remaining cylinders by applying a real-time, flexible crankshaft model combined with an adaptation algorithm. The single-cylinder pressure sensor concept is implemented on CPU/field-programmable gate array–based hardware. For steady-state engine operating conditions, the added value of the adaptation algorithm is demonstrated for cases in which a fuel quantity change or start of injection change is applied in a single, non-instrumented cylinder. It is shown that for steady-state and transient engine conditions, the cylinder pressure traces and corresponding combustion parameters, indicated mean effective pressure, peak cylinder pressure, and crank angle at 50% heat release, can be estimated with 1.2 bar, 6.0 bar, and 1.1 CAD inaccuracy, respectively.