Simulation and Evaluation of a Variable Valve Timing Single Cylinder Spark Ignition Engine

A Comprehensive computer simulation model was developed for a single cylinder spark ignition engine to simulate the Compression, Combustion, Expansion, Exhaust and Intake processes including the heat losses through the cylinder walls. The gas exchange processes were simulated with the help of a finite difference scheme and a separate boundary condition was developed for the throttle action on a conventional carburetor. The model after validating with the experimental data was used to arrive at the optimum duration and lift of the intake valve corresponding to different throttle positions of the equivalent conventional engine. These optimum values were used in the design of a 3 dimensional cam. Based on this design a new variable valve timing engine (VVT) has been designed and developed. Comparison between the computed and experimental data for the VVT engine was observed to be satisfactory. It is anticipated that the present technique could pave the way for the design and development of a variable valve timing engine.