Integration And Application Of Fuel Adjustment Characteristic Test System

The fuel injection spectrum of the electronically controlled gasoline engine is completely solidified in the ECU.In addition,the current injection control of the engine uses negative feedback control.It is difficult to control the injection amount of the engine without an external electronic control development system.Therefore,colleges and universities that do not have the ability to develop electronically controlled ECUs have stopped or canceled the fuel-tuning characteristics test for gasoline engines.In view of the current status of the industry,it is necessary to develop a more universal experimental device that can be connected to most existing engines on the market.An experimental device for adjusting the characteristics of gasoline engine fuel can be completed without changing the original ECU.This subject takes modern gasoline engine as the research object,and studies the development status of electronically controlled injection system of gasoline engine in detail.Based on the characteristics and research needs of four-stroke gasoline engines,the principles and requirements of software and hardware design for this subject are proposed.Based on this,the following work was done:(1)An in-depth study of gasoline engine was carried out,and the development status of gasoline electromechanical injection system and the influence of air-fuel ratio on engine emissions,economy and power were analyzed in detail.The wiring mode and driving mode of the gasoline engine fuel injector are studied.(2)The STM32F103 microcomputer is used to design the hardware system of the experimental device.The hardware system includes a fuel injection signal acquisition circuit,a fuel injector circuit,a relay switching circuit,and a resistance display screen to display and set the injection pulse width circuit.In order to make the development circuit board more regular,the topic integrates the system into a circuit board.(3)The software system of the electric control unit is designed.Firstly,the overall program logic block diagram is designed.Using the idea of sub-modules,the acquisition module program,the driving fuel injection program,the resistance display screen to display the injection pulse width,the set experimental value module program,and the relay switching program are designed.Through the R-232 interface,the communication between the resistance display screen and the single-chip microcomputer is realized.The experimental device for fuel adjustment characteristics is completed by setting the injection pulse width without changing the original ECU.This project has completedhardware and software development.(4)Using the existing engine test bench,the fuel adjustment characteristic test of the gasoline engine was completed.That is,by changing the injection quantity of the engine,the relationship between the gasoline engine's emissions,economy,and power and the excess air coefficient was measured.