Design And Dynamic Analysis Of V-type Engine Timing Silent Chain System

Timing system is an important part of the engine gas distribution system and itsmain function is opening and closing the intake and exhaust valve in an accurate andtimely manner by controlling the valve opening and closing moments according to thework order and the working process of the engine, so that the combustible mixture ofair is charged into the cylinder in a timely fashion while the exhaust gas is dischargedfrom the cylinder. Thus the ventilation process is achieved and the engine has a goodpower output performance. In recent years, in order to meet the needs of high-speedautomobile engine, a growing number of engine gas distribution systems begin to usethe silent chain timing system. However, silent chain timing system of the domestic islong-term dependent on foreign imports due to the lack of engagement mechanismand design method of the silent chain timing system, which has seriously hamperedthe development of domestic independent brand.On the basis of elaborating the research status of the timing chain system andwith the help of modern design methods, this paper combined a project of QingdaoChoho Industrial Co. Ltd to put forward a design method for the the V-type enginetiming silent chain system and its various components and then analyses the dynamiccharacteristics of timing silent chain system.On the basis of elaborating the ventilation process of the automobile engine andgas distribution process of the system, this paper analysed three factors which affectedthe ventilation process: the delay angle of the intake, exhaust advance angle and thevalve overlap angle.Among them, the delay angle of the intake had the greatest impacton engine performance. Then this paper introduced the valve timing technology andvariable valve timing technology. Based on analyzing different engagementmechanisms of silent chain meshing process, this paper compared the advantages anddisadvantages of different engagement mechanisms and their application conditions, which provided a solid theoretical foundation for the design of silent chain timingsystem.This paper calculated the transmission power of the timing system and theeffective circumferential force and the silent chain of static strength factor of safety,then designed the overall layout of the silent chain timing system and put forward thedesign and calculation method for the timing silent chain system and its variouscomponents according to the timing box size and related parameters provided bytiming system manufacturers. The pitch of the chain plate and design parameters ofthe chain plate were obtained refer to the value calculated on the last step. Theparameter of the sprocket was acquired in view of the principle of silent chainmeshing process. Arm guides and the tensioner guide were designed to refer to thedegree of tightness for each side of the the silent chain system and their radius ofcurvature were calculated. Next, the length of silent chain in the timing chain wascalculated and rounded to take an even multiple chains according to the curvatureradius of the guide and the angle of the tensioning guide was obtained with the help ofthe Matlab program and the maximum working stroke of hydraulic tensioner wascalculated according to the condition of the force in loose side of the silent chainsystem.This paper analysed the dynamic characteristics of the silent chain timing systemin three working conditions of driving sporcket:1000r/min、3000r/min and5000r/min.This paper analysed the polygon effect of the timing silent chain system by focusingon the trace of the timing silent chain system polygon effect and proposed a new ideato design the system structure of timing silent chain system by modifying the trace ofit. This paper researched the timing characteristics of the silent chain timing systemfrom the point of view of the silent chain drive efficiency and analysed the forces ofthe timing silent chain system to meet the static strength of the silent chainrequirements by analysing the force between the chain tension and the reaction forcechain plates and tensioner.The analysis results shown that this V-type engine timingsilent chain system met the requirements of design and complex and changing workenvironment.The results of analysis were shown that this paper presented the design methodwas scientific and feasible and the research results of this paper had extremely important practical significance for improving the capability of independentinnovation of timing silent chain system and the process of autonomy.