Development And Study On Key Technologies Of Miller Cycle Engine

The development of new technology to achieve more efficient,environmentally friendly and energy-saving internal combustion engine is necessary to meet the future requirements for emission reduction and fuel economy.More and more technologies,such as the Miller cycle combustion,were applied to improve the engine thermal efficiency and economy with low emissions.By adjusting the intake and exhaust valve timing,the Miller cycle combustion had the relatively low air charge temperature and pressure in the compression-stroke,which would increase thermal efficiency and fuel economy with lower pumping loss and makes higher geometric compression ratio design possible,furthermore,the maximum torque at low engine speed could be improved but tendency of knock would be increased.The present status and development trend of gasoline engine technology research were mentioned in this work.Using experiments conducted on one 1.5L turbocharged engine,comparison of the performance and emission characteristics induced by different plans of injectors,turbochargers and camshafts,etc.were studied and the final plan was set.Besides,the development goals,the design of combustion system,the experimental condition control and emission control strategies were introduced.The calibration of electronic control system parameters was conducted on the prototype engine with the final plan design mentioned above by using some calibration tools such as INCA and CAMEO.The influence of valve timing on fuel consumption,emission characteristics,pre-ignition tendency on high intake temperature condition and model calculation accuracy was investigated.Furthermore,the control strategies under the warm-up operating condition were studied.