Mechanical Retractor Noise Evaluation on Electrodynamic Shaker: Test Procedure 2018-01-1532
Modern vehicles are driven with various speeds over specific rough road tracks to detect the presence of annoying buzz, squeak and rattle sounds. As known in the occupant safety industry the mechanical locking systems of seat belt retractors can be significant noise sources, when excited by road vibrations.
A reliable bench test procedure is necessary to quantify the acoustic performance of retractors, verify production quality, and derive realistic acoustic product targets. With this goal, a vibration noise test procedure has been developed condensing the work over three years by the K2 Comet automotive research project X2T1, various OEM retractor noise specifications closed to public and own research. The load case in this specification has been defined as horizontal 60 Hz bandlimited broadband excitation, while the N10 instationary loudness metric has been selected to characterize the retractor acoustic performance. A single load case along with a single value linear metric have been found to adequately characterize retractor noise without added test complexity. The enhanced reliability can promote the selection of a more silent retractor type and eases discussions in the automotive industry about retractor noise. This publication offers a developed test procedure, with the potential to reduce the number of retractor noise procedures currently in use.