Estimation of Combustion Phasing Using the Combustion Net Torque Method

Paper in proceeding, 2011

A new and computationally efficient method, called the combustion net torque method, for estimating combustion phasing in an internal combustion engine using crankshaft torque data is presented. The work is motivated by the need of such an estimation method for real-time implementation of a torque based closed-loop combustion phasing control system. The ideal properties of the proposed method, based on torque calculated from cylinder pressure, are studied using simulations and experimental data from both a spark ignited and a compression ignited engine. A relation to 50% burned mass fraction, the most common measure of combustion phasing, is established and the robustness of the method is investigated. The results show that the ideal estimation accuracy of the proposed method is high, especially around the combustion phasing position where maximum engine efficiency is achieved. Also, the computational complexity of the combustion net torque method is significantly lower compared to other existing techniques for torque domain combustion phasing estimation.