Performance Optimization For DCI11 Heavy-duty Diesel Engine

In recent years,the domestic heavy-duty diesel engine has been developing towards the direction of high power and high torque.Many diesel companies have launched their own heavy-duty diesel engine platform.The maximum power of the11L displacement engines is up to 323kW,and the maximum torque is 2100N·m.This paper deals with the problems of the comprehensive performance optimization including power,economy and noise performance base on a 11L displacement 420Ps engine.The optimization of the fuel injector,the pre injection strategy,the steady state and transient performance carry out.After optimization,the engine power is increased by 6.6%to 440Ps/323kW,and the maximum torque is increased by 7.5%to 2150N·m.In the study,the test of the injector selective preference,the simulation analysis shows that the engine fuel injection duration is too long when reached 323kW power index by base engine injector.This caused the fuel beam against the cylinder,and caused oil soot content very high.At last,a lager flow injector with 27%flow increased used to shorten the injection duration.That avoids the impingement of the fuel injection beam,and reduces the oil soot content by 72.1%compared with the base engine injector.In the pilot injection optimization,the relationship between engine noise caused by the rise of cylinder pressure and pilot injection parameters is investigated.The noise and rise of cylinder pressure are more sensitive to the pilot injection switch strategy,but not sensitive to the pilot injection timing and quantity.Finally,by expanding the range of pilot injection opening,the noise mutation problem of the engine during the free acceleration test and the vehicle acceleration process solved.In the steady state calibration optimization test,the MBC toolbox is used to build engine model.The NO_x emission calculated according to the weight of the law is used as the boundary condition,and the optimization results are obtained by optimizing the calculation of the fuel consumption calculated by the weight of fuel consumption.The fuel consumption weight of the base engine is obtained by the reverse solution.The fuel consumption weight distribution according to the difference of the road spectrum of the base engine and the dCi440-51 engine is investigated for the ESC fuel consumption calculating.In the transient calibration test,it was found during the analysis of the basic engine that the calibration of the smoke limit mainly played a role in the PM emission,and had no effect on the NO_x emission.Therefore,two different methods used to calibrate NO_x emission and PM emission respectively.The K-means clustering algorithm used to transform the ETC test cycle into a steady state test cycle with 12operating points.By calibrating the NO_x emission of the steady-state cycle,the NO_x emission requirements of the ETC test cycle reached.The constant speed with increasing torque test of different loads was realized by the method of piecewise constant speed with increasing torque.Then by comparing the peak opacity smoke peak of different load load-step test,the engine load area caused the peak opacity smoke is located,we can calibrate the smoke limit accurately,and achieve the PM emission target of the ETC test.