Study Of Key Technique For Cng Engine Controller

With the increasing of automotive quantity, the contradiction of oil and emissionpollution become more serious.Alternative fuels researching will be the hot spot in theautomotive industry.Due to abundance of NG and its low emission, NG become theideal alternative fuel.This study is a part of CNG engine product development, whichis a National863project. This paper mainly design key technique of CNG enginecontroller and do experiment researching. Achievement of this work will promoteproduct development process of CNG engine electronic control system.This paper introduce development and technique ways of CNG automotive andCNG engine control system briefly, especially explain UEGO’s structure,characteristic and its operating principle.We also introduce structure and configurationof the CNG engine control system.On the base of project’s aim,we design the schemeof CNG engine ECU and accomplish configuration and selection of components.In the development process of CNG engine controller,We use MC68376ascentral chip of Motorola,and design peripheral circuit based on internal module ofMC68376followed by V type developing model,including power circuit,referencevoltage circuit,reset circuit,input signal processing circuit and output driving circuit.Based on the theory of UEGO, we develop UEGO control module and heatercontrol module.This AFR and temperature output characteristic will be optimized andcalibrated in the engine bench experiment. We also use separate component to designUEGO control module elementarily.Control software development is one of the most important steps in the lifecycle of electronic control unit development.This paper mainly develop the software ofsignal measurement module,UEGO heater driving module, we also take some CANcommunication researching.We also design HIL simulation platform for the CNG engine electronic controlsystem and could debug function of the controller easily, and optimize the CNGengine controller on this platform.Engine experiments indicate that the CNG engine controller’s performance isstable, and the UEGO control module operate accurately, stably on the wholeoperating conditions.This controller realize AFR closed loop control, and performanceof engine achieve project anticipating goal.