| Summary: | 碩士 === 崑山科技大學 === 機械工程研究所 === 91 === The V-belt Continuously Variable Transmission (CVT) systems are widely used in almost all kinds of scooters. The major mechanism of the traditional CVT is composed of centrifugal rollers, the compression spring and the torque cam. They are used to adjust the speed ratios for complying with the engine speed and the rear wheel load. In addition to the low transmission efficiency at the lower speed, the centrifugal rollers and movable flange have the worn-up problems which may reduce the materials life-cycle. In order to improve these problems, the aim of our study is to design a brand new Electronically-Controlled Continuously Variable Transmission (ECCVT) system to overcome the limitation of the traditional CVT mechanism. In stead of the centrifugal rollers and movable flange, the new ECCVT use the electronic control equipment to change the speed ratios. Therefore, it gets rid of the material worn-up problems. The ECCVT system can also provide the overall system with higher durability and reliability, and the accurate movement. Combined with the sensor signals of the engine speed, the vehicle speed and the TPS (Throttle Position Sensor), the suitable speed ratio can be calculated. One ECCVT system can be used for different types of engines and in different kinds of driving conditions. By controlling the shift timing and the changing speed of speed ratios, the ECCVT can fulfill the various engine configurations and loading. Therefore, the ECCVT system can be expected to have better power transmission and higher energy transferred efficiencies.
At the present stage, the design and experiment test of the new ECCVT system have been accomplished, the experiment results show that the ECCVT system can provide a better transmission efficiency at the lower speeds and the worn-up problems can be avoided. When the external load is changed from 1.16 N-m to 5.8 N-m, the transmission efficiency increases from 45% to 80% obviously. But the increasing tendency is becoming smoothly when the load is above 3.48 N-m. Based on the dynamic test data, the average transmission efficiency of the ECCVT system is 5% higher than that of the traditional CVT system. But, if the speed changed of speed ratio is too fast, the transmission efficiency will drop obviously while the speed ratio starts to change and latter-on the transmission efficiency will increase with the increasing speed ratios.
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