Study On Vibration And Noise Characteristics Of Rounded-jointed Silent Chain System Based On Multivariate Variation

The rounded-jointed silent chain system is an indispensable part of the chain drive type,which has a very wide applications and outstanding advantages.This paper is supported by NSFC Project “Research on Variation Mechanism and Key Design Technology of Silent Chain”(51305154)and Jilin Province Science and Technology Planning Program “Research on Multiphase Hy-Vo Chain System Key Technologies”(20150204075GX).In this paper,the multi-variation types,the variation characteristics of meshing mechanism,the system vibration characteristics and acoustic radiation characteristics of the rounded-jointed silent chain system are studied respectively.Specific research contents are as follows:In this paper,the concept and necessity of multi-variation of silent chain system are elaborated.The specific variation forms of shape variation,parameter variation and meshing mechanism variation of rounded-jointed silent chain system and its importance are introduced.In addition,a new type of silent chain is described.In this paper,in order to study the variation of meshing mechanism of rounded-jointed silent chain system,five simulation models of with different meshing mechanism are established to analyze the movement trajectory and angular velocity fluctuation of the marker chain plate.The results show that the inner-outer compound meshing plates plays a more prominent role in reducing the meshing impact of the rounded-jointed silent chain system and improving the transmission accuracy than the outer meshing plate.In this paper,the finite element model of the rounded-jointed silent chain system is established,and the vibration characteristics are explored.The pre-stressed modal analysis is performed.Results show that the system vibration mostly occurs on the driven sprocket and the loose and tight sides,and the stress is concentrated in the crotch of the chain plate.The crotch of the chain plate belongs to the weak area.Frequency response analysis of silent chain system is carried out.Results show that most of the natural frequencies are far from the excitation frequencies,and the probability of resonance is small.In addition,the sixth natural frequency is slightly similar to the excitation frequency.Under this frequency,the maximum stress distributes near the start position in the meshing between the tight side and the drive sprocket,but the stress value is far less than the yield strength of the material,indicating that the parts of the system will not instantaneously fail when in the case of resonance.In this paper,the noise mechanism of the rounded-jointed silent chain system is analyzed,and three kinds of excitation factors are summarized,including machining and assembly error,stiffness excitation and meshing impact excitation.The specific excitation forms and characteristics of the three kinds of excitation factors are introduced,as well as the importance and research value of meshing impact excitation.In order to study the noise characteristics of the rounded-jointed silent chain system,the direct boundary element method(DBEM)was used to simulate the acoustic radiation of the system.The main frequency of noise,the main location of noise source and the characteristics of noise pressure distribution at different frequencies are explored by experiments.The acoustic radiation analysis of the rounded-jointed silent chain system verifies the accuracy of the harmonic response analysis using meshing impact as the exciting force of the system,and verifies the correctness of the analysis of the noise mechanism,which provides a strong theoretical basis for the optimization of the structure and the suppression of the vibration and noise of the silent chain system.In summary,the multi-variation types of the rounded-jointed silent chain system are summarized,and the meshing mechanism variation is studied deeply,which lays a foundation for the next personalized research of the rounded-jointed silent chain system.The vibration and noise characteristics of the system are studied respectively,which provides an important reference for subsequent improving system performance,optimizing system structure and further exploring the NVH characteristics of the silent chain system.