Combustion And Emission Performance Optimization For Low Emission Outboard Gasoline Engine Based On The Electronic Controlled Technologies

As a vertical shaft gasoline engine,the outboard engine suspended on the boat is a power propulsion system.At present,China has produced small-power outboard engine and needs to develop medium-power and low-emission outboard engine.With the improvement of environmental protection requirements,European and American countries have strict emission regulations.Therefore,it is a great value of academic significance and engineering application to research on high performance and low emission outboard gasoline engine.The research object was outboard engine F60.The technical route of foreign outboard engines was analyzed,the high performance and low emission technical program were achieved by using open-loop electronic controlled system and optimizing combustion system.Combination methods of simulation calculation and experimental research were adopted to optimize the structure of the intake and exhaust system by the steady flow test rig.The flow coefficients optimized of intake and exhaust ports were increased by 10.56%and 8.28%respectively and the air volume intake was increased.The constructions of the electronic controlled intake manifold injection system and the ignition system were completed,the excess air ratio map was set under different operating conditions.The software Ricardo Wave was used to establish the simulation model and set boundary conditions,the power,fuel consumption and main emissions of the outboard engine were studied by adjusting Excess air ratio and ignition advance angle.The influences of E4 mode on combustion and emission of NOx,HC and CO were analyzed under different operating conditions.The variation tendency of excess air ratio,ignition advance angle and power,economy and emission performance of F60 outboard gasoline engine was obtained.The multi-schemes of excess air ratio and ignition advance angle were analyzed at different operating points of propeller characteristics,the quantitative characteristics of mixture concentration and ignition advance angle were obtained.Combined with the simulation results,the excess air ratio MAP and the ignition advance angle MAP of the electronic controlled system were formed.The F60 outboard gasoline engine was experimented,the final CO emission result was 169.5 g/(kW·h)and the HC+NO_X was11.42 g/(kW·h),the results accounted for 56.5%and 65.5%of the EPA emission limits respectively.According to the standard,the Not-to-exceed zone constructed was tested and the results met the emission limits.By 350 hours of deterioration test,the F60 outboard gasoline engine met the limits of US and EU emission regulations.Compared with the similar engines of international famous enterprises,the performance and emission of the F60 outboard gasoline engine reached the advanced level.The study on combustion and emission control scheme of medium-power electronic-controlled outboard gasoline engine conduces to promote the development of outboard engine technology in China.