Design analysis of torsichrone centrifugal pendulum vibration absorbers

The number of applications of centrifugal pendulum vibration absorber (CPVA) in the automotive industry is growing steadily. The request of low fuel consumption and torque increase at low speed stimulated a large variety of drive concepts, such as downsizing, cylinder deactivation and hybrid powertrains. These design solutions increased the severity of torsional vibrations as well as the need of more effective devices to damp them out. For this reason, in recent years new types of CPVAs have appeared on the market. In particular, a pendulum with trapezoidal architecture, called torsichrone, has been developed. Its distinctive feature consists in the exploit of absorbers rotational kinetic energy for additional vibration attenuation. This paper investigates the kinematics and the nonlinear dynamics of trapezoidal dampers by means of intrinsic geometry theoretical tools and perturbation methods, respectively. It also offers insights about the influence of absorber center of mass path on the overall performance. Furthermore, optimization criteria for the rotational component of absorbers motion are proposed. On the basis of such analyses, design guidelines are recommended. Finally, to assess vibration isolation effectiveness and local stability behavior of trapezoidal CPVAs, a numerical comparison with the tautochrone parallel pendulum and results of multibody dynamics simulation are discussed.