Effect of Valve Clearance on Performance and Emissions of Diesel Engines
Valve clearance is a key parameter of traditional diesel engines,and a reasonable valve clearance should take into account engine reliability,performance,and emissions.By testing the performance and emis-sions under steady-state operating conditions on an engine test bench,the relationship between different intake and exhaust valve clearances and engine performance and emissions is studied.The experimental results show that the impact of intake valve clearance on performance and emissions is relatively small,while the impact of ex-haust valve clearance on engine performance and emissions is much greater than that of intake valve clearance.The exhaust valve clearance has a significant impact on the engine charge efficiency,especially at high speeds and heavy loads.The charge efficiency of a 0.4mm clearance is 0.027 higher than that of a 0.2mm clearance;Due to the influence of valve clearance on charge efficiency,the exhaust valve clearance has a greater impact on the ex-haust temperature of high-speed and heavy loads than other areas.Valve clearance causes a 14.3℃decrease in exhaust temperature;The emission of nitrogen oxides is positively correlated with exhaust valve clearance,and its impact on nitrogen oxides at medium,high speeds,and high loads is greater than in other regions;Carbon smoke emissions are generally negatively correlated with exhaust valve clearance,which has a significant impact on low speed and medium load conditions.Valve clearance reduces smoke intensity by 0.12 FSN.
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万方数据
维普
