Theoretical And Experimental Study On The Dynamic Characteristic Of Metal Pushing V-Belt Type Continuously Variable Transmission

The metal pushing V-belt type continuously variable transmission (CVT) is an ideal transmission system, which offers significant advantages for performance and fuel economy for automobile. Study on the transmission mechanism and dynamic characteristic of CVT has important theoretical meaning and engineering practical value. The creative results on dynamic characteristic of CVT and transmission mechanism based on system theoretical analysis and experiment research are acquired under the project (59835160) financed by National Science Foundation.The mechanics models of metal-bands transmission concerning clamp force of pulley, axial force, thrust and tension is built based on Coulomb friction theory. The forces acting on the metal blocks and rings of CVT are respectively calculated under different conditions, and factors including component parameters, speed ratio influenced on load distributing are analyzed. The transmission mechanism of the CVT driving by tensions and thrust force tension is revealed; the important conclusions among axial force of pulley, torque, rotate speed are drawn.For the first time, the theoretical system on the dynamic characteristics of metal-belt continuously variable transmission is put forward and established. The transmission model composing of the driving axis, driving pulley, driven axis, driven pulley, metal blocks and metal rings is built and the node-node rod discrete finite element model is proposed. The dynamic characteristics of metal-belt continuously variable transmission are theoretically studied under different conditions, which lays a theoretical foundation for dynamic qualification research, improvement of load capacity, dynamic response analysis and evaluating the fatigue life of the transmission system.For the first time, the experimental modality analysis on the key component composed of metal rings and blocks is studied. The modal frequencies, damp ratios and modal shapes of subsystem are obtained; problems in deciding boundary condition of finite element model are resolved, which provides an important basis for noise and vibration reduction.The principle and method of ambient test is studied. For the first time, the modal parameters of the CVT are identified by the acceleration signal of the CVT picked up in transmission test bench when the transmission system is in operation. The difficult problem that can not be solved by common experimental modality analysis is overcome. The experiment conclusions coincide with theoretic solution and bear theoretic research out.For the first time, the vibration characteristic of CVT is studied in transitional and steady state. The law of the vibration characteristic of CVT influenced by different input rotate speeds, torque and speed ratio is studied in time and frequency domains. After the mechanism of CVT in the transitional state is studied, distributing rules and relationship between the speed change ratio and torque under different conditions are investigated online by the means of three-dimension waterfall at constant interval, which providing theoretical evidence for noise and vibration reduction, for improving comfort of car.The theoretical system and testing analysis methods put forward in this paper settle basis for the mechanical optimization, the dynamic response analysis and evaluating fatigue life of CVT.