Theoretical Analysis of Performance for Roller Type Centrifugal Pendulum Absorber

The development of fuel-saving technologies has been an important issue in the automotive industry to respond to global warming and energy problems. On the other hand, in the power train, the technology to improve fuel efficiency by combining downsizing and turbocharger has been put to practical use and has spread mainly in Europe. To reduce the displacement of the engine, it is effective to reduce the number of cylinders. However, reducing the number of cylinders increases torque fluctuations from the engine and deteriorates NV performance. Therefore, the importance of torsional vibration reduction technology has been increasing rapidly in recent years, and research and development are being actively carried out. Among them, the centrifugal pendulum absorber (CPA) using pendulums type dynamic vibration absorber has been put into practical use, because it exhibits a vibration reduction effect in almost all rotation speed regions by changing the natural angular frequency of the pendulum in proportion to the rotation speed. Denman has found the epicycloidal trajectory in which the natural angular frequency of the pendulum does not depend on the pendulum amplitude, derives the Lagrangian equation when damping the pendulum is ignored, and examines the effect on the system when CPA is attached. When the pendulum trajectory is a circular orbit, it is difficult to optimize because the natural angular frequency of the pendulum changes depending on the pendulum amplitude. On the other hand, in the epicycloid trajectory in which the natural angular frequency does not depend on the pendulum amplitude proposed by Denman, it is easy to aim for the fluctuation order of the torsional vibration to be reduced, but the performance is exhibited only in the region very close to the resonance point. Recently, the roller type CPA has been investigated because it is very simple structure and it has a similar characteristic of pendulum type CPA. However, the effect of the trajectory has not been clarified for the roller type of CPA. Therefore, in this study, focusing on the roller trajectory for the purpose of improving the performance of roller type CPA, the influence of the trajectory on the vibration damping performance of roller type CPV is clarified. In order to clarify the influence of the roller trajectory, in the theoretical analysis, the roller trajectory is an arbitrary path and it is represented by a 6-order function. Next, in order to verify the effectiveness of the theoretical analysis result, a multibody dynamics model corresponding to the theoretical analysis model is developed and the results of both are compared. Furthermore, theoretical analysis calculations clarify the influence of the roller trajectory on the performance of CPA numerically.