Coordination Control Of Speed And Air-fuel Ratio For Marine Natural Gas Engine

At present,the breakthrough of new technology for marine natural gas engine is mainly focused on the research of electronic control system.In recent years,a large number of simulation software has shorted the development cycle of the engine control system,but as a multivariable,coupled strong,real-time changes in parameters of the controlled object,the natural gas engine is not possible to obtain completely authentic data by simulation modeling alone.Therefore,this study aimed at Yuchai Machinery Co.,Ltd YC6 K natural gas engine,designed and developed a complete electronic control system,then designed the hardware and software of the bottom drive and the engine management system in detail,and completed a series of experiments to verify the control system through the actual matching machine.On this basis,the coordination relationship and control mode between the speed and air-fuel ratio of natural gas engine are studied deeply through experiments.Air-fuel ratio is one of the core parameters of natural gas engine,how to maintain proper air-fuel ratio to ensure full combustion in various working conditions is also one of the key factors in control system research.Unlike automotive engine based on torque control,the marine engine is based on rotational speed control,that is,to control the engine to achieve a certain speed regulation power relying on the target speed of the car clock under the precondition of satisfying the economic emission requirement.So this paper studies the air-fuel ratio and rotational speed which are the two key control elements of natural gas engine,and analyses coupling relationship of coordinated control between them through the experiment,and puts forward a new control strategy combined with experimental verification to get a certain rule.The developed natural gas engine controller by this study can control the throttle opening,ignition advance angle,injection pulse width and so on precisely and independently,and can achieve the coordinated control of rotational speed and air-fuel ratio under different operating conditions.The experimental results show that the closed-loop strategy of auto-tuning PID can guarantee the stability of the steady-state time and space combustion ratio,and the feedforward MAP is used to obtain a better transient response of the air-fuel ratio.After the experiment,the target Air-fuel ratio is set to the fixed value equivalent value,the actual air-fuel ratios of different working conditions are got by changing load,then the values are labeled on the MAP as the new target Air-fuel ratio,and the control strategy is perfected.At last,the control effect is tested in transient condition by means of sudden adding and sudden unloading load and set rotational speed target value,and the control law of the speed and air-fuel ratio of this type of natural gas engine is experimentally studied,and the power of the control system is verified.