| Development of valve switching mechanism is the key to the variable strokeengine. A kind of valve switching mechanism, which has the function of strokeswitching and valve timing adjusting, was designed on the basis of Honda WH125-6engine. The working mode can be switched between two stroke mode and four strokemode through the action of the switching mechanism. So the power of the engine canbe improved without changing the displacement and mass.The engine camshaft is designed, it consists of the CAM worked in four-strokemode and the CAM worked in two-stroke mode. The working mode can be switchedby changing the position of the CAM. The switching mode, lubrication mode,positioning mode, and transmission mode are designed in this paper. According to theexperiments, it proves indirectly that the switching mechanism can work well in thesingle mode.Based on the law that the small deformation in the coupled multi-body can havean impact on the operation of the mechanism. The simulation model of valve train isbuilt based on the multi-body dynamics theory, and the simulation model of the engineis built based on the thermodynamic theory. The engine performance is influenced bythe deformation of the CAM, and its law has been got. Then, compared with theexperimental data, it has showed that the experimental data curve is close to the engineperformance curve under flexible CAM.The control program and the virtual prototype are combined using the jointsimulation of ADAMS and MATLAB. So the engine mode can be switched under theengine switching signal. The parameters of the switching mechanism in workingprocess, the limited speed with rocker flying off, the appropriate spring stiffness forpositioning can be achieved.In preparation for the experiment of the switching mechanism, the NC machiningsimulation and forming are carried on with CATIA. And some problems in theexperimental process are salved, including the design of the engine seat, the modification/design and processing of the rockers. |
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