Study On Low Emission Performance Of Single Cylinder Air-Cooled Diesel Engine With Electronic Unit Pump

The production and application of single cylinder air-cooled diesel engine are very large in China.The China?emission standard of non-road diesel engine is quiet strict with small-power diesel engine,and China?emission standard of non-road diesel engine will be implemented in2020.Therefore,the research on low emission technology of single cylinder air-cooled diesel engine has an important academic significance and engineering application value.This paper analyzes the main technical route of small-power diesel engine to reduce the emissions of the 195FD air-cooled diesel engine.Electronic unit pump system is used to optimize the emissions of the diesel engine,due to the cost,diesel engine structure and other factors restriction.According to the working characteristics of the electronic unit pump,the fuel supply cam profile of 195FD diesel engine with uniform speed section is designed to make sure that the oil supply rate is high at different oil supply advance angles.Combustion system is designed by increasing the hole number of the nozzle,optimizing the flow of the nozzle,increasing the combustion chamber diameter appropriately,designing the space reasonably,increasing the compression ratio appropriately,reducing intake swirl,and reducing inlet and exhaust resistance.In order to improve the engine performance and reduce the engine emissions,the matching experiment was carried out to optimize the diesel engine combustion system parameters.The characteristics of fuel supply delay and fuel injection delay were obtained by analyzing the fuel injection process of the electronic unit pump system.On this basis,the MAP of the cycle fuel supply and fuel supply advance angle were set,and calibration tests of the oil supply advance angle and the working section were carried out.The variation of combustion process of low emission diesel engine were analyzed by measuring tubing pressure and cylinder pressure.As a result,to reduce the HC and CO emissions at the light and medium loads,the fuel supply advance angle was increased as the load decreased,and the fuel supply advance angle of10%load condition was 5°CA ahead of that at full load.To reduce the NO_X emission,the fuel supply advance angle at calibration speed was 9°CA ahead of that at 1600 r/min to ensure a slight increase in the fuel injection advance angle,and this can also control the variation of the combustion timing and combustion process of diesel engine at different speed conditions to optimize the NO_X,HC,CO and smoke emissions.The optimal MAP of fuel supply advance angle under different speed and load conditions are determined by calibrating the diesel engine.The initial emission results of CO,HC+NO_X and PM are 3.87,5.92 and 0.31 g/(kW·h).195FD diesel engine has met emission standard in the environmental protection department,and this engine is the only one single-cylinder air-cooled diesel engine that has met the China?emission standard of non-road diesel engine by using electronic unit pump system.According to the China?emission standard of non-road diesel engine,the emission control area of the 195FD diesel engine is determined,and the emission of multiple working conditions in the control area is measured.The results show that the emission of the diesel engine are lower than the limits of the China?emission standard of non-road diesel engine.This paper studys the technology for reducing the emissions of single cylinder air-cooled diesel engine with electronic unit pump system.The research work can guide the technology of reducing the small-power engine emissions.