Abstract
In order to improve CVT (Continuous Variable Transmission) used for automobiles, the breakdown test is assigned. When it was tested under conditions of a high-speed rotation and high load of transmitted torque at the examination, the torsional vibration problem in the input-output shaft system is generated and the examination can’t be continued. This paper considered the cause of this 198Hz-vibration problem the countermeasure. As a result, we got the following knowledge: (1) According to experiment including a variety of operation of testing machine, we found out that the limitation beyond stable zone depend upon the rotational speed and transmitted torque. (2) The analytical approaches gave two results: one understood that the onset of this unstable self-excited vibration stable condition is caused by the negative damping property of CVT belt frictional force and the other that the most severe vibration which should stop our machine is generated by the parametric excitation. The mechanism of this parametric excitation was made clear that it happens at very narrow condition of a certain frequency relationship, i.e., the deference between two natural frequencies of input and output shaft equals to the output shat speed. (3) For the troubleshooting, our solution is to install dynamic mass damper which is featured by setting the natural frequency of the damper being agreed with the natural frequency of the input shaft. Finally, I achieved stabilization of the self-excitation vibration.
