Sugil Choi, Taeoh Tak*
The Journal of Mechanical Science and Technology, vol. 25, no. 2, pp.293-299, 2011

Abstract : The purpose of this research was to analyze the dynamic behavior of a seatbelt system, focusing on the kinematics of its motorized retractor mechanism as well as its overall performance. The motorized retractor was modeled based on the multibody principle, taking into consideration of the detailed kinematic configuration of the one-way clutch mechanism, which is the critical component of the system. The conditions for fail-safe operation along with the effects of the design parameters of the clutch were studied. It was found that groove length is the most significant design parameter in the engagement and disengagement process. The seatbelt model was setup integrating motorized retractor, flexible webbing and dummy models into a single dynamics system. The validity of the model was confirmed by the good correlation of the simulated and measured webbing forces values obtained from a pre-tensioner detonation test. Using this model, the dynamic performance of the motorized-retractor-driven seatbelt system was evaluated according to a predetermined scenario, and the effectiveness of the retractor’s control of driver posture regardless of the initial torso position was investigated. It was concluded that the seatbelt-driver interaction model can be used as an effective and practical design tool for motorized retractors as well as entire seatbelt systems.

Keyword : Seatbelt system; Motorized retractor; One-way clutch; Webbing; Multibody dynamics