Research And Design Of Electronic Control System For LNG Engine

With the increasing number of vehicles,the oil crisis and the pollution ofenvironment become more serious,so an eco-friendly alternative fuel forvehicles is widely concerned.Because of the abundant reserves and thelow-emission characters,atural gas is a good choice.The liquefied naturalgas(LNG) is becoming more popular these years, because it is clean andhas long driving range as well as better emission performance, therefore,developing a LNG engine electronic control system with excellentproperties has profound significance.In this paper,the NQ120N engine was became to a LNG engine bymodified its fuel supply system,NG temperature control scheme is designedin order to solve the impact of the different temperature of NG whichgasified from vaporization in different conditions, then the electroniccontrol system was designed after the engine was modified.According to the performance of LNG fuel,the design of electroniccontrol system is based on the MC9S12XS128MCU. The hardware systeminclude the design of ECU circuit, digital signal processing circuits, analogsignal processing circuits and actuator drive circuit. The peak-hold typedriving circuit of the NG gas jet valve and the single-cylinder independent ignition driving circuit are used according to the characteristics of LNGengine.The control strategy of engine jet and ignition is studied, and thesoftware is designed by using the idea of modularization, including theflow chart of main program, working procedure and interruptsubroutine.. In order to improve the anti-interference of the system, a seriesof hardware and software anti-interference measures are adoptedThe average LNG model and the test bench model of the engine areestablished by using Matlab/Simulink, and the initial MAP chart of the jetand ignition angle is obtained by using the method of simulation.. In orderto realize the initial MAP data easily and quickly, the virtual simulationcalibration system to obtain the engine MAP is designed.The loop simulation experiment was established in the upper computermonitoring which was developed by LabVIEW,mainly include the jetsignal and ignition angle signal in different conditions.According to theresult of the test,the electronic control system was proved to be correct andreasonable.