| Abstract |
In order to protect the environment and reduce carbon emissions, regardless of fuel vehicles or hybrid electric vehicles, the focus of engine development for vehicle is to reduce displacement and increase efficiency. The improvement of the efficiency of the traditional four-stroke Otto engine can be improved very little, almost reaching the limit, so the Atkinson engine is adopted. Its extension stroke is longer than the compression stroke, and the efficiency is higher than that of the same displacement Otto cycle engine, so some car manufacturers use it with electric motors as the power output of hybrid electric vehicles. This paper discuss the efficiency of the Atkinson cycle engine and the Otto cycle engine, and give a mechanism synthesis simulation of the Atkinson engine with Python programming. In theory, increasing the compression ratio of the Otto cycle will improve the efficiency, but the improvement rate is getting lower and lower. From the efficiency improvement rate simulation results, it can be seen that the compression ratio is most suitable at 11.5, which is close to the actual engine. In the Atkinson cycle, the stroke volume ratio increases from 1 (as Otto cycle), the engine efficiency increases, but the improvement rate also decreases, and the increase in the extension stroke makes the mechanism design difficult. Simplify the Atkinson engine mechanism into a combination of four-link and slider mechanism. This article also uses Python's Mechanism module to synthesize the Atkinson engine mechanism. The stroke volume ratio can be calculated from the results of the Atkinson engine mechanism motion simulation. |
