Research On The Performance Of China Ⅳ Off-Road Diesel Engine

As Off-Road Emission Regulation becomes more and more stringent,China had released Off-Road Stage 3 and 4 Emission Regulation requirement on 2014,and on 2016 Stage 3 has be executed,so Stage 4 also will be carried out on future.To meet more stringent regulation requirement,the article based on 7.8 litres diesel engine,first clears the working points of test bench experiment、parameters and requirement of test instruments and sets up the method of dynamic performance evaluation,then does the research on emission performance、economic performance and dynamic performance base on the factors of injector、turbo charge、injection advance angle and pressure.Base on theory simulation calculation,we find the influence of cylinder combustion temperature、equivalence ratio and injection rate by different injector hole number、injector hole diameter(flow)、injection angle.Then through experiment data,verify the theory simulation calculation.As the result,the proper increase the number of injection holes is beneficial to the combustion in the cylinder,it can increase the cylinder temperature,increase NOx,but decrease particle,fuel consumption.The appropriate decrease of fuel injection flow is beneficial to fuel atomization and fuel injection duration,which can bring the reduction of CO and HC.The appropriate increase of the injection spray angle is proper with the combustion chamber,which can bring the decrease of smoke.In order to meet requirements of the emission and the applications of off-road vehicles at the same time.By choosing different compressor with same turbo,do the research on the influence of emission performance、economic performance and dynamic performance.Through experiment data,we find that smaller compressor turbo charge compares with bigger one,brings more intake air mass on middle and low speed,faster dynamic performance,better requirement of off-road vehicles application.As the same time,smaller compressor turbo charge brings better economic performance.Refer to the emission performance,two type trubo charges are almost the same.Finally,with the same injection pressure,we do the experiment by changing the injection advance angle on the 8-conditions operating points.We find that the appropriate increase of injection advance angle is beneficial to the combustion in the cylinder,which results in the decrease of the particles and fuel consumption,but the increase of NOx.Then at the same injection advance angle,we do the experiment by changing the injection pressure on the 8-conditions operating points.We find that the proper increase of pressure can make fuel atomization better,bring better fuel and air mixing,and also promote the decrease of particle and fuel consumption,but also increase the NOx.