Study On Electronic Control System Development And Performance Of CNG Single-Fuel And Multi-point Injection Engine

Title:Study on Electronic Control System Development and Performance of CNG Single-Fuel and Multi-point Injection EngineMajor:Transportation Environment and Safety TechnologyAdviser:Prof.Wang YunpengIn recent years,along with the rapid development of China's automobile industry,China has become the world's fourth largest auto producer and second largest consumer,but the cars brought about by the surge in oil shortages,air pollution are problems which auto industry can not avoid.The search for clean alternative fuel vehicle,to reduce dependence on oil,reduce emissions,the automotive industry has been a hot topic.In a variety of alternative fuels used by the car,CNG relying on its advantages such as economy,low pollution emissions,rich reserves,which has become the most widely used vehicle alternative fuels in the world.In this paper,combined with co-operation project of Brilliance inc and Jilin University, Mitsubishi 4G64 engine converted single-fuel CNG engine for research,the development of electronically controlled multi-point fuel injection CNG single-engine control unit,and the engine's electronic control system calibration工作.In order to give full play to the CNG fuel economy,low emissions of pollutants from the advantages of solving the transient engine operating conditions poor air-fuel ratio control precision,this paper has established the average amount of engine model(MVEM),application-based model MVEM state predictor Transient condition of the gas into the accurate estimates that the design of the transient condition air-fuel ratio control strategy to achieve the status of transient air-fuel ratio is more precise control.This paper shows that the development of tests to verify the electronic control system software and hardware design;CNG engine and emission control accuracy has been improved significantly.The main work are as follows:(1)Analyzing of CNG engine's electronic control system's working principle and its problem,especially on the CNG engine air-fuel ratio control theory and methods in-depth analysis,in order to solve the problem of air measuring device's lag in response and the air flow's large measuring error caused by the intake manifold in charge of the gas emission effect in transient conditions,the paper established a CNG engine intake of the average amount of dynamic model(MVEM). (2)A design of air flow's measurement method based on state predictor.In order to achieve better control accuracy,using the Kalman filter to estimate the non-linear system of sta(?)e and parameters to achieve accurate measurement of air flow,the algorithm test study shew that the design of measurement and control algorithms with a quick response,real-time and effective filtering.(3)Application of Italy's landirenzo OMEGAS' Gas supply equipment,completing more points CNG inlet sequence jet engine modification work in the Mitsubishi 4G64 electronic control gasoline engine,building the CNG engine test platform.(4)For CNG engine's work characteristics and control demand,selecting single-chip of Motorola MPC555 as the main ECU chips.The modified CNG engine using the original engine sensors and ignition control system,on the basis of full analyzing the hardware characteristics of sensors and actuators,re-design the sensor input signal processing circuit and the actuator hardware device driver circuit,taking into account hardware aspects of the anti-jamming measures to improve the reliability of the work of the control unit and anti-jamming performance.(5)Performing an deeply analysis of control process of electronic control system, studying multi-tasking technology and analysis of the structure of the interruption,according to the actual input and output needs,reasonably determine the different tasks' priority,as well as the different interrupt request priority.(6)Designing the CNG engine start-up optimization control strategy,warm-control strategy,the estimation of transient conditions' control strategy based on the MVEM model's air flow calculation algorithm,as well as the engine steady-state strategy,so that the CNG engine can work in different conditions,but always working near ideal air-fuel ratio to achieve reducing emissions and fuel consumption.For engine control calibration parameters, the design of PC calibration procedures;carried out anti-jamming electronic control system software research and put forward concrete measures.(7)Study of the excess air ratio and ignition timing control,and other control parameter's impact on the CNG engine power and emissions,after full analysis of the impact on engine power,economy and emissions,getting excess air ratio and ignition timing Map in steady State conditions.Through the comparison test of CNG engine based on model control and look-up table control,performing an analysis of model-based control features.The results show that the design of MVEM model-based control of the CNG engine in the transient speed up process,can be accurately and quickly control the air-fuel ratio, effectively reducing engine emissions,has reached the desired results.(8)For the trial process,the valve seat of serious wear and tear,poor reliability,analysis of the valve seat of the reasons for failure to re-design a new valve seat materials,the trial showed that the new valve seat material meet the requirements of use.The main innovation points are as follows:(1)Performing an deeply analysis of the CNG engine's poor air-fuel ratio control accuracy in transient condition,the paper established a CNG engine dynamic model(MVEM) based on the average amount,and designed air flow measurement method based on state predictor,replacing look-up table methods.Using the Kalman filter to estimate the state and non-linear system parameters.Tests show that the air-fuel ratio control strategy designed in this paper,can be accurately and rapidly control of the air-fuel ratio,effectively reducing engine emissions.(2)Using 32-bit high-performance CPU MPC555 and carrying out the ECU-specific software and hardware development:for the work characteristics of CNG engine,the ECU had a multi-task real-time control algorithms.The latter test shows that the developed ECU meet the needs of the CNG engine in the function and performance.(3)For CNG engine test,the emergence of serious valve seat wear,poor reliability, in-depth analysis of the valve seat of the reasons for failure to study the valve seat material by grinding principle,design a new valve Seat material,the trial showed that the new valve seat materials used to meet the requirements.