Torsional Vibration Analysis Of The Crankshaft With Rigidly Coupling Rubber V-belt CVT

CVT is often used in the transmission mechanism of automobile and motorcycle for its flexibility characteristics of shifting. CVT is often used in car by laying a clutch or fluid coupling between crankshaft and the CVT. However, in some cases because of the cost or restrictions, the clutch or hydraulic coupler is not allow to be lay, such as a motorcycle or UTV and other single cylinder engine often rigidly coupled CVT with end of the crankshaft. Now because of the limitation of structure, CVT is rigidly connected with the crankshaft of four-cylinder engine. Also the torsional vibration of the four-cylinder engine crankshaft is one of the major causes of engine failure, so this article will study torsional vibration parameters of CVT rigidly coupled crankshaft to analyze its feasibility. Details are as follows:① In order to quickly understand the impact of crankshaft torsional vibration for CVT rigidly coupled with the crankshaft of four-cylinder engine, crankshaft torsional vibration modal of finite element is calculated for the crankshaft of four cylinder clutch CVT and rigid connection CVT. It found that the torsional vibration modal frequency for crankshaft with rigid connection CVT of four cylinder is one more than crankshaft with clutch CVT of four cylinder, and the extra order frequency is lower than the original frequency. In order to study the characteristics of the crankshaft torsional vibration at the extra frequency, finite element technique has been used to verify the equivalent CVT structure. It is preparation for the following calculation.② For crankshaft with rigid connection CVT of the four-cylinder engine will cause one more order of free vibration frequency, it computes the torsional vibration parameters of four-cylinder crankshaft with clutch CVT by firstly to understand its torsional parameters. And also it is compared with experimental data to ensure the accuracy of the model. Then it is modeling and calculation to the crankshaft of four-cylinder engine with rigid coupled CVT that base on the equivalent CVT structure combined with the crankshaft of four-cylinder engine with clutch CVT. And it understood the characteristics of torsional vibration parameters of the four-cylinder engine crankshaft with rigidly coupled CVT. It found that torsional vibration amplitudes and shear stress at end of CVT for the four-cylinder engine crankshaft with rigid connection CVT is comparatively large than the four-cylinder crankshaft with clutch CVT.③ Address the above problems, the torsional vibration parameters of the crankshaft with rigid coupling CVT and clutch CVT of single-cylinder engine were analyzed, and it learned that the torsional vibration parameters features for the crankshaft of single-cylinder engine. Through comparative analysis, it found that it is much lower for the crankshaft torsional vibration of the single-cylinder engine than the crankshaft of four-cylinder engine, and the crankshaft of single-cylinder engine does not appear the same characteristics as the crankshaft torsional of four-cylinder engine that value of shear stress and amplitude is very large at the CVT end. So the structure of the four-cylinder engine crankshaft rigidly coupled CVT requires further optimization and validation.