Software Design Of Gas System For Dual-fuel Engine And PID Control Strategy

In current world, the research on clean alternative fuels tends to be an incrementally important discipline of engine techniques due to the shortage of the global petroleum resource and the serious air pollution problems. Especially, the Compressed Natural Gas (CNG) has being used extensively as a clean alternative fuel on engine. Thus, gasoline/CNG dual-fuel engine is dominant in the CNG engine for its high efficiency and low mission. In order to promote the development of the dual-fuel vehicle techniques in China, the research on the basal theory and the experiments on the electronic controlled gasoline/CNG dual-fuel engine should be carried out.This paper introduces a series of electronically controlled gas injection system designed based on 477 dual-fuel engine. It is consisted with two major parts: gas jet modules and ignition module. ECU hardware system adopts PIC2420 single-chip as the core device and designs a reasonable input and output circuit. A gas jet module is using the closed-loop oxygen sensor control strategy of gasoline ECU to acquire its feedback of the pulse width. Meanwhile, the gas jet module uses the method of the timer freedom interrupt to achieve the adjustment of the four-cylinder gas pulse width control. Ignition module achieves the premise of changing the crankshaft signal as conditions with the method of tracking crankshaft signal. As well, it uses the gasoline ECU's ignition control strategy to achieve the spark advance angle closed-loop control strategy.To point out MAP online and amend the parameters of condition, this system researched and developed the back-stage monitoring software. It achieved the display of status parameters and the real-time modification of control parameters through serial communication. The software of Electric control system calibrates the gas MAP and ignition MAP on Chery A15 cars through the test of the software protus. Being combined the method of look-up table with oxygen sensor closed-loop feedback control with ignition control strategy of gasoline ECU, the Electric control system pass the nation III(GB18352.3-2005) gas detection experiment.Finally, the idle experimental data of gas status is used to model for the jet module of dual-fuel engine. With the simulation research of the methods of location-type PID control and incremental-type PID control, it is proved that the incremental-type PID control method is better for the closed-loop control of dual-duel engine.