Study On Control Strategy And Performance Of Natural Gas Engine Meeting China Stage Five Emission Regulations

With the oil resource becoming deficiency, vehical emmissions limit has become increasingly strict. The new resource development for gas as substitute resource will become the main development in automobile industry. The research purpose includes: get rid of the rely on oversea Natural gas engine electronic control system technology, master the key skill of natural gas engine control, develop independent intellectual property rights of the meet the power performance and emission requirements of the natural gas engine electronic control system.First of all, the research has been done on the main gas engine control system and aftertreatment of exhaust technical route, combine the condition of our country to verify the electronic control injection system and machine optimized combustion and SCR post-processing technology route plan.Research and analysis have been done on the key components of Electronic Fuel Injection and structure of electronic throttle valve and opening control principle, besides, the close loop control model has been built including continuous current dynamo, back-moving spring and Friction torque reduction gear group via Matlab. The simulation result showed that opening control has good responsiveness, following performance, thus lay a solid foundation for the control of electronic throttle valve.On the foundation of Electronic Fuel Injection accuracy control, we introduced the Knock the throttle flow estimation model, combined with Speed density method flow estimation model, to estimate the Natural gas engine steady state transient air-fuel ratio control of air volume, thus improved the control effect of speed density estimate model of transient air-fuel ratio.SCR after treatment techniques have been done for natural gas engine and we have done research on the NOx emmission, air flow and SCR catalytic conversion efficiency. In addition, the rerearch has been conducted on the urea solution injection rate according to engine nox emission pulse spectrum, and the steady state has been made and exhaust temperature mutation transient conditions urea solution injection rate control strategy.Engine rig test has showed that natural gas engine has better air-fuel ratio than control effect, In the natural gas engine operating conditions can be well follow target air-fuel ratio value; ETC test cycle showed that natural gas engine emissions has set to China stage five emission standard and meet the goal of subject research.