The Research And Realization Of The Uniformity Control Strategy Of Each Cylinder Of The High Pressure Common Rail Diesel Engine

During engine operation,the torque output from each cylinder is inconsistent due to differences in the amount of circulating fuel injection,combustion characteristics,and wear of the components in each cylinder.Unbalanced output torque of each cylinder will lead to intensified torsional vibration of the engine crankshaft and deterioration of NVH characteristics,which seriously affects the working stability and reliable durability of the diesel engine.The cam curve has a great influence on the injection process of the conventional diesel engine,so it is difficult to reduce the unbalance of the torque output of each cylinder on the conventional diesel engine.With the development of diesel high pressure common rail injection technology,diesel fuel injection can be accurately calculated and accurately controlled.The Cylinder Uniformity Control is the basic requirement for ensuring the stable operation of the diesel engine,and is the key technology for improving the uniformity of combustion of each cylinder in the cycle and improving the comprehensive performance of the diesel engine.Aiming at the problem of non-uniformity of torque output of each cylinder of high pressure common rail diesel engine,the Cylinder Uniformity Control is designed by systematically analyzing the fuel injection control mechanism of diesel engine.The control strategy is divided into two functions: non-uniform quantization and correction injection quantity calculation.The unbalanced measurement function uses the segment signal of the engine to quantify the unbalance of each cylinder through the missing tooth processing,the resampling processing and the band pass filtering.The corrected fuel injection calculation function can calculate the corrected fuel injection amount of each cylinder based on the quantitative result and the current working condition.After the calculation is completed,the control strategy distributes the corrected fuel injection amount of each cylinder to each injection based on the desired injection amount of each injection.By analyzing the uniformity control function requirements of each cylinder,the uniformity control model of each cylinder was constructed by MATLAB/Simulink software.Through the model in-loop testing and software-in-the-loop testing,the control strategy is functionally verified,and then the control model is integrated with the diesel engine control system independently developed by the laboratory,and the bench test is carried out.The test shows that the uniformity control strategy of each cylinder can accurately correct the fuel injection amount in the range of 800 rpm to 1300 rpm and injection volume of 2 milligrams per stroke to 50 milligrams per stroke.To achieve the purpose of reducing the torque output unbalance of each cylinder and optimizing the NVH characteristics.