Supply System Simulation And Injection Control Of The CNG Engine

Natural gas, as one of the most potential alternative energy in the21st century, isincreasingly applied to the cars. Gas-fueled vehicles have both good economic performanceand emission performance. Therefore, with the increasing promotion of this kind ofautomobiles in the market as well as the development of engine electronic control technology,it’s not hard to say that the requirements for control systems of natural gas engines will bemore and more demanded. Thus it is of great academic significance and practical value to doin-depth research and analysis on the CNG engine control system, as well as to improve andperfect the CNG engine performance.Based on the modeling and simulation platform of multidisciplinary field and complexsystem, namely AMESim software, the simulation model of CNG engine’s gas-supplyingsystem and the control model of the incremental PID in the idle speed are established. It isproved that its injection law obeys the working law of the nozzle through doing experimentson the jet flow of the electronically controlled natural gas nozzle. The results of the idle speedPID control model show that the engine excess air coefficient fluctuates within1, whose idlespeed is relatively smooth, which realizes the demanded requirements that the control systemcan control automatically, which makes the idle speed relatively stable in operation.The present situation of the CNG engine development is analyzed in the paper, throughwhich the CNG engine gas supply system and jet control are functioned as the research object,and by which the overall scheme is designed for injection system of the CNG engine. TheFreescale16-bit microprocessor, namelyMC9S12XDP512, is developed as electronicallycontrolled muti-point sequential gas injection systems of the microprocessor. Meanwhile, thehardware and software designs are made for the electronically controlled gas injection system.On the aspects of the hardware, the article provides modules of the signal input, centralcontrol unit and actuator driver. Also, researches on the CNG engine injection control strategyare well waged. In addition, in view of the control strategy for the control software design,some programming are provided, including the main programming of the system, as well asthe programming of jet control program design, the injection pulse width calculation and theimputing programming of the input signal in the software system.Based on the thorough analysis on the high-speed electromagnetic valve drivetechnology of the gas nozzle in the paper, an effective way is put forward to reduce theheating phenomenon of the MOS tube and solenoid valve, as well as to improve the stabilityof the system and component’s life, which is operated under a driving mode by maintainingthe high pressure to low pressure through hardware and software.Using homemade electronically controlled engine experimental instrument V1.0laboratory equipment, Accomplishment the debug and simulation experiments for the injection control hardware system of the gas engine. Test results show that the injectioncontrol system can satisfy the need to accurately control the injection moment and width ofthe injection pulse, upon which the injection drive waveform conforms to the requirements ofthe design, Testing nozzles current of software controlling mode at different voltages,different PWM wave period, duty cycle, Test nozzle flow of the hardware controlling mode.At last, the shortages of system are provided and improvement scheme and measure etcare given in this paper.