| As a common transmission mode in engine timing system,silent chain drive has been widely used in the engine field because of its high transmission efficiency and strong carrying capacity.This paper is supported by Science and Technology Development Project of Jilin Province “Key Technology Research on the Timing Chain System of Passenger Vehicle Hybrid Engine(20200401136GX)”and National Natural Science Foundation project “Variation Theory and Key Design Technology of Silent Chain(51775222)”.In this paper,the parameter design of the timing silent chain system and its simulation model are established.It is found that the timing silent chain system is reasonable in design and meets the needs of actual work through a series of simulation comparison and analysis.At the same time,this paper provides some reference for further research on vibration and noise reduction of timing system.The specific research contents are as follows:In this paper,the overall layout of the timing silent chain system is designed according to the position coordinates and the size of the space provided by the engine manufacturer.Afterwards,each component of the system: chain plate,sprocket,tensioning guide and fixed guide are designed with parameters,and the overall design of the timing silent chain system is completed finally.In this paper,the geometric model of the system is established in CATIA,and its physical model is established in Recur Dyn,a dynamic analysis software,by applying kinematics constraints,driving constraints and other initial conditions.Finally,the trajectory,transmission ratio and angular velocity are selected for comparative analysis under three different rotational speeds.The results show that the engine timing silent chain transmission system designed in this paper runs smoothly and meets the requirements of actual working conditions.Based on the finite element model of the timing silent chain transmission system established by Ansys Workbench,this paper studies the vibration characteristics of the timing system designed.It is found that the maximum stress and maximum deformation of the system meet the requirements of material properties through the static analysis of the entire system.The mode shapes and corresponding natural frequencies of the timing silent chain system are obtained under the modal analysis with prestress.The modal analysis results show that the vibration of the system occurs mostly on the side of the crankshaft sprocket near the tensioner and the span stage of the two camshaft sprockets.The contact force between the chain plate and the sprocket extracted from the dynamic simulation analysis is added as an excitation force to the frequency response analysis of the system.And the results of the harmonic response analysis show that the position where the system is prone to resonance appeared at720 Hz.In this paper,the acoustic radiation simulation model of timing silent chain transmission system is established by the acoustic radiation analysis software Virtual.Lab Acoustics to study the noise characteristics of timing system.The response function curve of sound pressure frequency in the simulation calculation results shows that the main frequency of system noise is 720 Hz.By extracting the sound pressure distribution nephograph of the timing silent chain system at this frequency,it can be found that the system noises are mainly distributed on the side of the crankshaft sprocket near the tensioner and the span stage of the two camshaft sprockets.This result is basically consistent with the main vibration location in the finite element simulation analysis,which verifies the accuracy of the timing system noise analysis in this paper.In summary,the multi-body dynamics simulation,vibration characteristics and acoustic radiation simulation analysis of the timing silent chain transmission system are studied,which laid a certain research foundation for the subsequent optimization design of timing silent chain system and the NVH research of engine timing system. |
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