Design of a highly efficient friction clutch apparatus for vehicle applications using a self-energizing mechanism

Abstract

This study proposes a new design for a friction clutch actuator using the self-energizing principle for vehicle applications such that the power consumption for clutch control is significantly reduced. The self-energizing effect can be created by simply adding wedge structures to a conventional clutch system, and it assists in significantly reducing the actuation energy of the clutch with little additional cost. In this paper, a mathematical model of the clutch actuation system is derived on the basis of static force analyses with particular emphasis on the torque amplification factor due to the self-energizing effect. The slope angles of the wedges in the proposed clutch actuator are determined in order that the clutch system ensures appropriate torque amplification while considering various factors such as the variations in the friction coefficient and the return spring force. In addition, model-based analyses of the new clutch actuator system are performed in order to predict the dynamic effects of the self-energizing mechanism on the system, particularly for the clutch engagement process. The feasibility of the proposed clutch design and its high energy efficiency are verified experimentally using three prototypes with different slope angles.