| Hy-Vo silent chain is a high-end product of the silent chain,which is widely used in various fields because it can significantly reduce the meshing impact and the noise in the transmission process.Supported by National Natural Science Foundation of China Project: Research on Mechanism of Variation and Key Technology of Silent Chain(No.51775222),the variation types,the internal tooth profile curve of inner-outer composite meshing plate,the calculation of the modification coefficient of sprocket and the dynamic characteristics of dual-phase Hy-Vo silent chain transmission system are studied in this paper.The specific research contents of this paper are as follows:The common variation types of Hy-Vo silent chain and the characteristics of each variation type are introduced,and the advantages and disadvantages of different types are analyzed in this paper.On the basis of previous work,a new variant design idea is put forward,that is,changing the internal profile curve of the chain plate of silent chain to improve the transmission performance.In this paper,the formulas of inner tooth profile curve of dual-phase Hy-Vo silent chain are obtained by using mathematical geometric analysis methods such as meshing principle of silent chain,pitch variation principle of Hy-Vo silent chain and coordinate transformation formula,and the corresponding inner tooth profile mathematical model is established according to the formula.Traditional calculation method of modification coefficient of Hy-Vo silent chain plate needs to determine measured distance over pins of silent chain sprocket beforehand.By structuring measuring pin in CAD and using measuring function in CAD,the measured distance over pins of processed sprocket can be calculated,which is cumbersome and not accurate.In this paper,a new method is derived based on the traditional calculation method of modification coefficient of Hy-Vo silent chain plate.Firstly,the chain plate-sprocket and hob-sprocket subsystems are established,then the modification coefficient is obtained based on the equation of the outer straight line of the chain plate with the change of the tooth half-angle of the Hy-Vo silent chain plate,the procedure of this method is simpler and the calculation accuracy is high.In this paper,a 3D model of the new inner-outer composite meshing plate is established based on the inner tooth profile equation,and two different silent chain systems are established in the dynamics software Recurdyn.The new type of dual-phase Hy-Vo silent chain system uses inner-outer composite meshing plate designed in this paper,and the inner tooth profile curve of the chain plate is described by the formula derived in this paper.The inner tooth profile curve of the inner-outer composite meshing plate of the traditional dual-phase Hy-Vo silent chain system is described by the comprehensive radius.In this paper,the transmission characteristics of two different systems are compared from the following aspects: tight side fluctuation of chain,rotating speed ratio of driving sprocket and driven sprocket,angular speed of chain plate,contact force of chain plate meshing into sprocket and so on.The results show that the fluctuation value of the driven sprocket of the new type of chain system is smaller when the speed reaches stable,and the running curve is smoother;compared with the traditional chain system,the tight side fluctuation amplitude of the new chain system is smaller.This is because the inner tooth profile of the plate of the new chain system is a smooth curve described by the equation derived in this paper.The new chain system runs more smoothly and can better reduce the polygon effect in the process of the silent chain drive.At the same time,because the inner tooth profile curve of the new chain plate is closer to the ideal mathematical curve of Hy-Vo silent chain,the contact force between chain plate and sprocket is smaller and the engagement is smoother than that of traditional chain plate and sprocket.In this paper,the pre-stressed modal analysis of the designed silent chain system is carried out by using workbench of ANSYS.The first six modes of the driving and driven sprockets are obtained by modal analysis.The results show that the stress produced by inertia load is very small and far from the yield limit of sprocket;The natural frequencies of the first six modes of the silent chain system are obtained by simulation,the first four modes are 617.26 Hz,627.34 Hz,629.27 Hz and 646.29 Hz,and the last two modes are 1650.4 Hz and 1660.1 Hz.The engagement frequencies of driving sprocket,driven sprocket and chain are 1166.7Hz and 1233.3Hz respectively,the engagement frequencies of sprocket and chain plate differ greatly from the natural frequencies of the silent chain system itself,so the chain system will not resonate.The design method of silent chain proposed in this paper provides a new idea for the variation design of dual-phase Hy-Vo silent chain system,and is of great significance to improve the transmission performance of Hy-Vo chain system and realize the independent intellectual property rights of high-end silent chain products at an early date. |
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