Virtual Processing And Dynamic Analysis Of High-speed Silent Chain Sprocket

Silent chain drive is widely used in the timing mechanism of gasoline engine, such as motorcar and motorcycle engine. However the polygon movement and the meshing contact effect of silent chain drive damages the synchronization and uniformity of transmission. It is necessary to develope new kind of silent chain drive to improve the transmission performance of silent chain mechanism.First of all, the polygon movement and the meshing contact of silent chain drive were analyzed. In order to reduce the meshing impact between the silent chain and the sprocket, to decrease the fluctuation of the chain at the high-speed situation, and to improve the stability of the chain drive, taking ObjectARX based on MFC as the designing tool, and using ADAMS as the analyzing tool, the design of a new tooth profile sprocket was developed. Based on the meshing process between the sprocket and the tight-side chain, simulated the shaped process of cutting by taking use of the Boolean operation of the software, the paper indicated the design method using the chain to envelope the sprocket blank to generate the sprocket teeth.The thesis pointed out the developing aspect of the design software that a part modeling with the enveloped surface, which is swept by 3D solid or surface, can be created. The study developed a software insert that can generate all kinds of spur gear modeling in the environment of AutoCAD, and based on that the study developed a software insert which can generate the involute sprocket model with a large pressure angle and a big modification coefficient. The thesis illustrated how to operate the entities in the AutoCAD database to do the position transformation, especially showed the relationship between the transformation matrix and the vector coordinates while doing the rotating transformation. The paper made some deviation analyse on the given model, got the relationship between the step number and the deviation of the tooth surface.The rigid dynamic models of two silent chain mechanisms (including the beeline profile sprocket and the involute sprockets separately mesh with the normal silent chain) were built by means of the 3-D modeling and mechanical dynamic analysis technology. The dynamic simulation of drive wheel at speeds of 500r/min to 8000r/min was achieved. The analysis results show that the meshing impact of the involute sprocket mechanism is less than the beeline profile sprocket mechanism in the same conditions, and the tight-side fluctuation of the silent chain of involute profile sprocket mechanism is larger than that of the beeline profile sprocket mechanism, and the driven wheel angle velocity nonuniformity coefficient shows the same situation with the tight-side fluctuation of the chain.