Research On The Relationship Between The Reliability Of Timing Drive System And The Moment Of Systematic Resistance

Timing drive system as an important part of the engine,its role is to transfer the power of the crankshaft to the engine valve mechanism,and then complete the control of the intake and exhaust.A good engine timing drive system should have the characteristics of compact structure,smooth operation,low vibration noise and low maintenance cost.The reasonable design of the timing wheel drive system affects the dynamic performance and reliability of the engine to a certain extent.The camshaft load torque is the resistance moment of the system that the camshaft is subjected to during the operation of the valve train,mainly from the reverse torque of the valve tappet acting on the cam tip,which is one of the excitation sources as the main factor in the design and analysis of the timing drive system,the periodical changes of size has a great impact on design and work stability of engine timing drive system,and even related to the normal operation of the engine valve mechanism.In this study,a four-cylinder four-stroke engine valve mechanism and a timing drive system are used as the test sample.And in the AVL-EXCITE Timing Drive module of multi-body dynamics simulation software,the multi-valve body is simulated and analog calculation was done to the original engine valve mechanism,then the variation curve of the camshaft load torque as one of the important boundary conditions of the timing drive system is obtained.As the engine is in the actual work process,there is the phenomenon of belt jump teeth,which will lead to phase disorder,valve and piston collision accident.Transmission torque increase is one of the important causes of belt jump teeth,and the camshaft bearing friction increase will make the camshaft load torque becomes larger,and then impact the engine timing drive system.In this study,the dynamic model of the timing drive system is established,and the camshaft load torque is calculated as the main boundary condition,and the dynamic characteristics of the components of the timing drive system are analog calculated and analyzed.Our main concern is whether the belt can be a smooth movement,including belt displacement,speed,acceleration,roulette speed fluctuations,belt and wheel relative sliding,etc.;Whether the belt can be smooth transmission,including the changes in transmission force,torque,and meshing points.In the meanwhile,the judgment condition and specific optimization scheme of the belt are proposed to improve the belt transmission smoothly,and the reliability of the belt drive reliability of the research model is also evaluated.