Engine Performance Optimizaition Based On Moving-coil Gas Fuel Injection Device

In order to improve the thermal efficiency and power performance of heavy-duty gas fuel engine,the research group developed a moving coil type electronically controlled gas fuel injection device,to realize high-power gas engine fuel supply timing,quantitative.It has many advantages such as large inject flow rate,fast reaction speed,easily controlled characteristic and so on,effectively improve the power and economy of heavy-duty gas engine.However,when the electronic control injection device is used in heavy-duty gas fuel engine,there are many problems,such as the optimal injection is not clear,and the thermal efficiency is low in some load conditions.Aiming at the above problems,the paper studies the heavy-duty gas engine by means of theoretical analysis,simulation calculation and experimental verification.Establishing and validating of simulation model of the engine working process,simulation and optimization of electronically controlled injection device of injection timing,research on the variable compression ratio and the application of Miller cycle in heavy-duty gas fuel engine.The performance of the engine and the injector is verified by the experiment,which provides a theoretical basis for the multi-point electronic control injection technology.Specific work is as follows:(1)The simulation model of the working process of heavy-duty multi-point injection gas fuel engine was established.Introduced the basic principle of engine working process,and the combustion model,heat transfer model and knock model of engine simulation model are analyzed and selected.And the reliability of the simulation model is verified by the experiment.The design and flow characteristics of electronically controlled injector for heavy-duty gas fuel engine are studied,lays the foundation for the research of the heavy-duty gas fuel engine with electronically controlled multi-point injection.(2)The timing of electronically controlled fuel injection for heavy-duty gas fuel engine is optimized.The joint simulation optimization platform of genetic algorithm and AVL BOOST simulation software is established.Analysis the influence of engine speed,load and fuel supply rate on fuel injection timing,and the constraint model for determining the injection starting point and end point.The influence of engine speed and load on injection timing is analyzed by means of fluid simulation.Under the different operating conditions,the fuel injection timing is optimized under different operating conditions by using the combined simulation optimization platform,and it has a certain effect on engine economic improvement.Comparative analysis of the performance of the engine is optimized when the premixed supply mode with electronic controlled injection,electronic timing optimization,engine speed range power full load average growth of more than 5.5%,improve the economics of more than 6.4%,the rated speed 1000r/min under each load economy improvement above 5.75%.(3)Exploration research the application of variable compression ratio and Miller cycle in heavy-duty gas engine.Under the premise that the engine does not knock combustion,optimized the compression ratio under various operating conditions,avoid the full load due to changes in fuel components caused by the knock and improve the economy of some load.Under moderate load,the thermal efficiency of the engine is improved by 4%~8%,and the thermal efficiency is improved by 10% under the condition of high speed and small load.Comprehensive application Miller cycle and variable compression ratio technology,and optimized the engine operating conditions,made the power performance under full load and the economy under part load has been improved to some extent,power and thermal efficiency can be improved by more than 10% under the condition of high speed and small load.(4)The experiment of heavy-duty multi-point injection gas fuel engine is completed.Analysis of the test results and the heavy-duty device of engine electronic fuel gas injection,analysis results show that the time of opening and closing of the electronically controlled injection device is 3.3ms and 2.9ms,valve lift(between 0~4mm)of injection device and pulse width can be adjusted continuously,the valve seating velocity is less than 0.1m/s,the high reaction speed and good control characteristics of the electronic controlled injector are guaranteed.The power of the engine under 1000r/min is 5.29% higher than that of the original engine;and gas consumption rate decreased by more than 7.5% in each load condition,and at least decreased by 5.7% in some cases,power and economy improve and optimization of injection timing simulation results of 5.65% and 7.2% coincides.The uniformity of each cylinder was obviously improved,and the effect was more than 10%.