Investigation On Power Performance And Fuel Economy Of The Gasoline Engine With Variable Valve Timing Strategy

Variable control for valve timing is one of the important issues for development of automobile technology. At present,Various device of variable valve timing have been widely used for the automobile engine. The main reason for the efficiency decrease at part load conditions for four-stroke spark-ignition (SI) engines is the flow restriction at the cross-sectional area of the intake system. Traditionally, valve-timing has been designed to optimize operation at high engine-speed and wide open throttle conditions. Several investigations have demonstrated that improvements at part load conditions in engine performance can be accomplished if the valve-timing is variable. Controlling valve-timing can be used to improve the torque and power curve as well as to reduce fuel consumption and emissions.In this paper, with a G10C engine as the research object, combine the real situation of the subject, the application of Variable Valve Timing system is studied applying the simulation analysis and experimental method. Major research work can be summed up as follows: Establish a model of engine by BOOST, and change the valve-timing to get the relationship between the valve-timing and the performance, than the trend of phase is obtained. Though the analysis of the structural characteristics and the influence factors of the VVT system and the performance test on the engine with the VVT system, the optimal phase under different conditions is found, the relationship between the valve-timing and the performance shows that the analysis results and the experimental results are consistent.Simulation and Analysis are confirmed by the experimental. The results obtained indicate that the variable valve timing strategy has a strong influence on the gas intake process, which in turn influences the engine parameters. In the rotate speed range of 2000r/min-4400r/min, the torque can achieve 8-10% improvement by the application of VVT system. At the same time, BSFC decrease 3%。At 4400r/min, the peak torque achieve 130.9 Nm,At 6000r/min, peak power achieve 72.6kw/h。This result basically achieve the target。By the analysis of the influence of intake valve-timing on both engine torque and fuel economy at different engine speeds, the relationship between the valve-timing and the performance is found, the trend of the phase is obtained, and the research provides better reference value for the application of the VVT system.