Research On Transient Air-feul Ratio Control Of Gasoline Direct Injection Engine

In the steady condition, it’s easy to control the air-fuel radio, but in the transient condition, it’s hard to control that because of the intake inertia, intake fluctuations, this will increase the pollutant emissions. In order to satisfy the emission regulation, the precise and quick Control of air-fuel ratio is necessary. So this paper proposed the Proportional-Integral-Derivative Neural Network(PIDNN) to control the transient air-fuel ratio and did following works:Firstly, based on a four cylinders direct injection engine, this paper built the engine model in AMESim, and according to this engine’s combustion parameters, built the single cylinder direct injection engine test platform.Then, after analyzing the PIDNN, this paper built the engine controller in Matlab/Simulink software. Using the interface between two softwares, the co-simulation was made to identify air-fuel ratio, and control air-fuel ratio in real time. The simulation load was selected as small and medium load conditions. This paper did the simulation at different engine speeds, and also did the simulation among different change rates of throttle opening.in transient condition.In the same throttle opening change condition, PIDNN control effect is better in higher speed than in lower speed.In different change rates of throttle opening.in transient condition, the control effect becomes better as the change rate gets slower. When the throttle opening changes from 10% to 40% costs more than 2s, the excess air coefficient always stays around 1. The changes of throttle opening have no influence on mixture concentration.Finally,this paper did the experimental study about air-fuel ratio control on a single cylinder direct injection engine, designed the air-fuel ratio control ECU software, accomplished throttle position measurement and control, intake pressure measurement, oxygen sensor signal collection, designed the throttle load change controller, accomplished the throttle opening change under precise time, designed the upper computer. The test load was selected as small and medium load conditions. This paper did the test at different engine speeds, and among different change rates of throttle opening.in transient condition.The test shows that PIDNN controller has very good control effect on air-fuel ratio. When the throttle opening increases, the excess air coefficient’s overshoot is under 1.2. When the throttle opening decreases, the mixture is enriched to about 0.8. And PIDNN controller gets the mixture back to the theoretical air fuel ratio within 2s. The test results show the PIDNN control strategy’s validity of the control on air-fuel ratio in reality.