| Air flow in loop scavenged process will have directly effect on the performances of gasoline engine, including power performance, fuel economy and emission performance. The intake system and the valve timing system have directly effect on the volumetric efficiency of the engine, which is one of the factors in the air flow in loop scavenged process. Variable intake pipe length technology can make better use of the effect of the gas fluctuation, which changes the traditional engine with single fixed structure, and can improve the volumetric efficiency and power performance and is an effective way of improving engine performance and reducing harmful emissions. As one of the new technologies of modern engines, variable valve timing technology which changes the traditional engines with fixed valve timing, can provide the best valve timing on the engine operating conditions and improve volumetric efficiency, and to a certain extent, can improve emissions, idling stability and low-speed smooth.In this paper, on the basis of gasoline engine working process calculation and software calculation principle of AVL BOOST. The TJ376QE gasoline engine work process model is established. Through validating the reliability of the model, the computational result and experimental result is almost consistent. On the base of the above-model, the performance of the gasoline engine is studied, the length of intake pipe length and the valve timing are optimized. The corresponding contour diagrams are compiled by using MATLAB to compare optimization. The changing point of variable intake system and valve timing system are confirmed. On the above base, the integrated performance of the gasoline engine is predicted with inner valve seat diameter of intake valve. The volumetric efficiency and the combustion properties of the gasoline engine can be improved under this optimum. The availability of variable intake system and valve timing system is discussed in theory. |
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