Driveline system development to overcome prop-shaft roughness phenomena

摘要

This paper determines the vehicle interior noise effects of the driveline system components. In a commercial vehicle development program; it has been found out that interior sound levels exceeds the target between mid engine speed ranges due to the high 4.5th, 5th engine order contributions through a resonance between 200-300 Hz. According to the vehicle level transfer path analysis performed in a semi-anechoic chassis dynamometer; root cause of the issue is identified as the excitation forces on the driveline-body attachment points (Center Bearing Points). And also possible triggering mechanisms of the attachment point vibrations have been determined as the relative prop-shaft angles & prop-shaft modal characteristics with respect to the earlier best practice cases. As the first step of the driveline system development; relative prop-shaft angles have been optimized by iterating the several angle configurations. After the driveline angle optimization; Prop-shaft design has been modified by using finite element tools in order to improve the frequency response characteristics of the assembly. Validation of the system modal characteristic has been performed by vehicle level measurements. In conclusion vehicle interior noise characteristics have been improved in order to achieve the program targets by developing the prop-shaft modal characteristics and changing the body attachment strategy.