Possibilities to identify engine combustion model parameters by analysis of the instantaneous crankshaft angular speed

In this paper, novel method for obtaining information about combustion process in individual cylinders of a multi-cylinder spark ignition engine based on instantaneous crankshaft angular velocity is presented. The method is based on robust box constrained Levenberg-Marquardt minimization of non-linear least squares given for measured and simulated instantaneous crankshaft angular speed which is determined from the solution of the engine dynamics torque balance equation. Combination of in-house developed comprehensive zero-dimensional two-zone spark ignition engine combustion model and analytical friction loss model in angular domain have been applied to provide sensitivity and error analysis regarding Wiebe combustion model parameters, heat transfer coefficient, and compression ratio. The analysis is employed to evaluate the basic starting assumption and possibility to provide reliable combustion analysis based on instantaneous engine crankshaft angular speed