Wiper System Dynamic Forces: from the Test Bench to the Vehicle

Acoustic comfort inside the vehicle is required whenever a wiper system is in function: front wiper motor noise is of great influence on the global comfort and its perception inside the car is 100% due to transmission of vibrations through wiper system fixation points on the vehicle. As any active source, both car manufacturer and system supplier need to be involved, at early stages of project development, in order to master the vibroacoustic integration of the system into the vehicle. This paper presents an experimental methodology dedicated to the front wiper system that offers the possibility to estimate the acoustic comfort inside the vehicle during project deployment phase, when modifications can still be proposed. Based on the XP-R-19701 standard, the procedure allows to measure, on a bench, the dynamic forces transmitted via the fixation points and details how to transpose them to the vehicle, taking into account the different specificities of the wiper system. Using a time recording of these dynamic forces and knowing the transfer path of the vehicle, the sound pressure inside the cabin can be estimated through various cycles and replayed by the car manufacturer. This methodology is a powerful tool that allows both car manufacturer and supplier to design the sound of the wiper system and can lead to accurate specifications for the wiper system supplier at very early stages of project.