Simulation Analysis of Miller Cycle on Performance of Supercharged Direct Injection Gasoline Engine

Abstract:

In this paper， the Miller cycle process of hybrid engine is mainly studied. A one-dimensional hydrodynamic model of intake camshaft with 130° wrap angle is established. The effect of Miller cycle realized by independent and joint adjustment of inlet valve opening （IVO） and exhaust valve closing （EVC） on engine performance is simulated and analyzed. It is shown that with the deepening of Miller cycle， under low load conditions，the intake exhaust gas reabsorption mass increases， the volumetric coefficient and pump mean effective pressure （PMEP） decreases， and the brake specific fuel consumption （BSFC） decreases； under medium load condition， the volumetric coefficient increases， the pump mean effective pressure decreases significantly，the crankshaft angle corresponding to 50% heat release rate （CA50） decreases， and the brake specific fuel consumption decreases； under high load conditions，the brake specific fuel consumption increases sharply. The combined regulation of IVO and EVC can further improve the engine performance and increase the thermal efficiency at the best fuel consumption point by 0.43%.

Key words:supercharged direct injection gasoline engine;Miller cycle;hydrodynamics;one-dimensional model