The Control Strategy Of Inhomogeneity Correction For Each Cylinder Of High Pressure Common Rail Diesel Engine Based On Rotational Speed Fluctuation

With the increasingly stringent internal combustion engine emission regulations,the exhaust treatment technology for diesel engine has made great progress,and it can effectively solve the problem of diesel engine tail gas pollution,so the diesel engine also is increasingly being used as a power source for passenger cars.But different from the gasoline engine,the diesel engine itself quality is larger,when the fuel injection of each cylinder is not uniform,the vibration of the body caused by the instantaneous speed fluctuation will be more serious,which will affect the comfort of the car and shorten the life of the diesel engine.Therefore,through the uniformity of each cylinder control system to reduce the fluctuation of rotating speed of diesel engine is imperative.Although modern diesel engines are all matched with special high pressure common rail injection systems,which can accurately control the injection quantity in each cylinder.However,due to the inevitable wear and tear phenomenon during the use of diesel engine,the combustion pressure of each cylinder is inconsistent,resulting in the larger and inconsistency of the instantaneous speed of each cylinder,which will cause the engine vibration.With the progress of microcomputer technology,the electronically controlled system of modern diesel engine is matched with high-performance microprocessor,which can make more precise control of the fuel injection of diesel engine.This provides a good technical platform for the control of the inhomogeneity of each cylinder.This study has sufficient support for software and hardware resources.The control unit of the test prototype adopts the domestic HT5 control system,which has the complete hardware and the underlying architecture.It can directly use the control unit to develop the control strategy of diesel engine.The software uses HT-Link calibration software,which can display the running state of the test prototype in real time,and also monitor and store the experimental data.Because the research content of this thesis is mainly to develop the control strategy to reduce the instantaneous speed fluctuation of each cylinder of diesel engine.Therefore,the rail pressure control,intake flow calculation and pedal signal acquisition and processing were optimized before the experiment to reduce the influence on the instantaneous speed fluctuation.And update the instantaneous speed algorithm before the experiment.The fluctuation of the instantaneous speed is taken into account from two aspects of the inside cycle and the outside cycle,by using the strategy of average fuel injection to reduce the fluctuation of the instantaneous speed between the cycles,and by using the acceleration contribution and the inhomogeneity of each cylinder to reduce the fluctuation of the instantaneous speed in the cycle.Therefore,the acceleration contribution and the content of the inhomogeneity of each cylinder are introduced in the control strategy.The fuzzy PID control system is integrated in the control strategy.To realize the PID selftuning,during the operation of diesel engine,the acceleration contribution and acceleration contribution rate of each cylinder is calculated as input of the fuzzy controller,and the output terminal is the corresponding PID controller parameter.In this thesis,the control strategies are simulated and tested respectively.The simulation model is used to verify the feasibility of the control strategy,and the effect of the control strategy is verified by the experiment.Through the analysis of the test data after the control strategy,we can see that the prototype runs at 1000r/min,and the control strategy can effectively reduce the fluctuation of its instantaneous speed.