New Method Research Of Diesel Engine Gas Recirlation Control

With the development of economy and the increasing of the number of automobiles, harmful emission of pollutants is a major problem in the world today. All countries has made strict rules about the emission of pollutants. Owing to the number of diesel vehicles is increasing, it is imperative to control the diesel engine emission. The main emissions of diesel engine are Nitrgen oxide (NOx) and Particle matter( PM ).It is difficult to reduce at the same time by engine internal purification. Besides, their corresponding after-treatment technology are not mature, so the research on diesel engine emissions control has broad prospects, meanwhile, it has important practical and social significance.At present, exhaust gas recirculation (EGR) has been widely used in nitrogen oxide purification. The development and application of EGR electronic control system had been further studied in foreign. Recently, the EGR application was studied in civil. Linear EGR walve structure and working process of EGR system were studied to establish EGR system mathematical expression, and build the corresponding physical model of EGR systems in MATLAB/SIMULINK environment. Fuzzy PID controller was designed and Smith predictor controller was improved, by simulating in the SIMULINK to get a good transient response.In order to effectively reduce diesel engine emissions of nitrogen oxides, The electronically controlled EGR system control strategy was analyzed. In this paper, a variable EGR rate closed loop control system which regard TMS320F2812 chip as the main controller and regard the engine speed and load as the input signal, and regard EGR valve opening as the feedback signal ,and regard the pulse signal of main controller as the output signal to control positive inversion and step number of stepping motor was establish, and the method of reducing diesel Particle matter and Nitrgen oxides was analyzed. The EGR system arrangement mode is designed and the determination of control scheme was analyzed. The hardware and software of the whole electronic control EGR system were designed. In terms of hardware, acquisition circuit of speed and load,stepping motor drive circuit,liquid crystal display circuit and other peripheral circuits were designed. In terms of software, speed and load acquisition subroutine,A/D sampling subroutine,stepping motor drive circuit subroutine,liquid crystal display subroutine were designed.