Dynamic simulation of a single-cylinder diesel engine including dynamometer modelling and friction

The recent drive to reduce emissions and improve efficiency means that there is a real need for improved models for the simulation of direct-injection diesel engines. With a view to improving the transient fuel control, a model of the non-linear transient dynamics of a generic direct-injection single-cylinder diesel engine is developed in order to predict the instantaneous engine speed and torque. The instantaneous crankshaft speed is determined from the solution of the engine-external load dynamics equation, where the engine torque is tracked on a crank angle basis. The model is based on an analysis of all the major forces internal to the engine and dynamometer. The friction components of the piston assembly, the bearings, the valve train, the pumping and the pumps are also included. The model is implemented in MATLAB/SIMULINK, and simulation results of both transient and steady state dynamics are presented. The simulation results of the instantaneous engine speed are compared with measured data, and it is seen that there is excellent agreement between them.