Combustion And Performance Evaluation Of Medium And Large Displacement Motorcycle Engine

Combustion analysis is one of the important research work in engine development, and combustion test is an effective way to evaluate the performance of engine. Therefore, as the foundation of noise control,fuel economy, and vehicle emission control, engine combustion test technology is the bond of performance parameters and control. The judgment and evaluation of products according to the combustion data is of great value in the process of research and development.In this thesis, specific analysis of different combustion data due to different cylinder pressure sensor was done according to engine combustion test. And the different evaluation in this situation was proposed. Besides, knock is easy to be noticed in medium and large displacement motorcycle engine.To solve this problem, different ignition advance angle curve is set in the prototype engine, different combustion data was acquired. Based on analysis of combustion test data, the best ignition advance angle is chosen at different speed and the original ignition strategy was optimized, in which the performance of engine was guaranteed and abnormal combustion was greatly diminished. And the significant influence of ignition advance angle in engine is verified. Furthermore, based on the test data of three engines with different displacement, performance parameters are compared, combustion process and heat release stability are analyzed, and abnormal combustion phenomenon are diagnosed. In the end, the developing direction of medium and large displacement motorcycle engine is proposed.The main work of this thesis is based on the engine combustion bench test, the basic data of the transient cylinder pressure, the maximum explosion pressure in the cylinder and the accumulated heat release were measured. And thus analysis of the mean indicated pressure, corresponding to the cyclic variation rate of indicated mean pressure, combustion pressure cycle fluctuations, maximum combustion pressure and corresponding crank angle, the maximum pressure rise rate and corresponding crank angle position, combustion knock intensity, combustion heat release rate, cumulative heat release rate and the combustion characteristic parameters of engine combustion(especially the flame development period and the rapid combustion period) influence in combustion. Finally through the data analysis of each prototype, evaluation is proposed and the corresponding engine optimization methods is put forward.