Comparative Evaluation of Seat Belt Retractor Websense Mechanism Rattle Noise

Seat belt retractors utilize mechanical sensors which, by their nature, rattle under moderate vibration loading. These sensors must be free to move however they must also be properly constrained in order to minimize rattle and its associated annoyance. The sensor under investigation, the websense, activates a locking mechanism when the seat belt acceleration reaches a certain maximum value. In one application, it was determined the rattle noise from this mechanism needed to be dramatically reduced; steps were taken to reduce that noise.

This paper documents the steps taken to effect noise reduction, including design changes, a computational investigation showing the relative contribution of each potential design change using the software N-hance.BSR, and laboratory-based rattle noise measurements comparing the final result to the initial product.