Engine control using real time combustion and compressible gas flow models

The goal of this project was to develop algorithms for controlling the operation of an engine with variable valve actuation. These algorithms were to be based on physical models allowing better control with fewer calibration tables. The control system was to provide good cylinder mass air charge and exhaust gas residual mass fraction estimates for engines with variable valve timing and variable valve lift.; A single cylinder research engine and a new single cylinder test system were used to develop these algorithms. Single cylinder research engines are normally tested under steady state conditions. To allow testing under transient conditions, a new test system was developed. The system utilized two new components. The first component was a high bandwidth single cylinder transient hydrostatic dynamometer that allowed rapid changes in speed, as well as replication of the multi-cylinder engine speed trajectory. The second component was an intake manifold airflow simulator that would reproduce the intake manifold dynamics of a multi-cylinder engine on the single cylinder engine. The complete system allowed transient speed and transient throttle testing on the single cylinder engine that was more representative of multi-cylinder operation.; The test system was then used to develop and test new engine control strategies. An engine model was developed using one-dimensional compressible gas wave dynamics for the intake and exhaust system along with a detailed thermodynamic model of the cylinder. The model was designed to operate in real time, allowing various estimated engine parameters to be used for controlling the engine.; The engine model was integrated with the engine control functions using a torque-based strategy and a carefully coordinated command structure. The engine model ran ahead of the engine allowing the cylinder mass air charge to be calculated and the correct amount of fuel to be injected for the corresponding cycle on the actual engine. The system provided accurate cylinder mass air charge and exhaust gas residual mass fraction information under a wide range of test conditions, with less calibration effort than traditional engine control techniques.