Design And Simulation Of Hydraulic Tensioning Systems For Timing Silent Chain Of Hybrid Passenger Vehicle Engines

This dissertation was supported by the National Natural Science Foundation project "Mutation Mechanism and Key Design Technology of Toothed Chain(51775222)" and the Key Research and Development Project of Jilin Provincial Science and Technology Development Plan "Key Technology Research of Engine Timing Chain System for Passenger Car Hybrid Power(20200401136GX)".The hydraulic tensioner plays an important role in the engine timing system and can compensate for the elongation caused by installation errors,chain wear,and stretching.At the same time,it can improve the vibration of the chain and reduce engine noise.Existing hydraulic tensioners in engine timing systems are basically improved and derived from traditional one-way valve-type hydraulic tensioners and are independent components of the engine system that cannot be adjusted by the vehicle control system.Therefore,based on the design requirements of a certain host factory,this paper proposes a new hydraulic tensioning system based on a dual-nozzle baffle servo valve control,builds relevant simulation models,and verifies the effectiveness of the scheme.The specific research contents are as follows:Firstly,after analyzing the limitations of the existing hydraulic tensioners and combining the relevant theory of electro-hydraulic servo systems,a design scheme for a hydraulic tensioning system based on electro-hydraulic servo control is proposed.According to the design requirements of the hydraulic tensioner for the hybrid power passenger car timing system proposed by a certain host factory,a dual-nozzle baffle servo valve is selected as the core control unit of the system,and a mathematical model of the hydraulic tensioning system based on the dual-nozzle baffle valve is established to construct the transfer function of the hydraulic tensioning system,and finally,a new hydraulic tensioning system is designed.Secondly,based on the Amesim simulation platform,a simulation analysis model of the servo valve-controlled cylinder and its auxiliary structure of the hydraulic tensioning system is built,and based on the transfer function model,the relevant characteristics are analyzed to verify the stability of the hydraulic tensioning system.Based on the Amesim-Simulink joint simulation platform,the characteristics of three different control strategies,position-based PID control,incremental PID control,and fuzzy PID control,are compared and analyzed in dynamic response,and the fuzzy PID algorithm is selected as the control strategy of the system because its response sensitivity and resolution can meet the design requirements.Thirdly,the joint simulation technology of Amesim-Simulink-Recur Dyn is used to analyze the dynamic characteristics of the designed hydraulic tensioning system.The sprocket speeds of the engine timing toothed chain system are set to 1000r/min,2000r/min,3000r/min,and 4000r/min,respectively,and the tension between the system chain plates,the running track of the chain plate center of gravity,the plunger stroke of the hydraulic tensioner,and the displacement of the tensioning guide rail are calculated.The results show that the timing chain system operates smoothly during simulation.In conclusion,the hydraulic tensioning system based on the dual-nozzle baffle servo valve proposed in this article is feasible.The designed hydraulic tensioning system has high stability,fast response speed,and strong anti-interference ability.The new hydraulic tensioning system can meet the design requirements of the host factory.