Structurally integrated piezoelectric actuators for reducing rear axle gear whine noise

The gear whine phenomenon in vehicles is a well-known acoustic issue which often needs a development of individual measures. Especially in rear- wheel and four-wheel drive vehicles, the acoustical optimization of the rear axle leads to the major goal conflict: improvement of the vibrational isolation of the rear axle versus excellent driving dynamics of the vehicle. A promising solution for this issue is described in this paper. The key objective is to reduce the noise contributions of the rear axle using an active vibration control system (AVC) based on piezoelectric actuators on the transfer path from the axle into the vehicle. In the first part of the paper, the development process of the AVC system is described. In the second part of the paper, a rear axle test bench is presented which is used to validate the simulation results. A multi component control algorithm has been implemented in order to get an optimum reduction of relevant forces at the mounting points to the vehicle using one or more actuators. In preparation for a series launch of the AVC system, an assembly concept for applying the piezoelectric actuators to the rear sub frame in a series production process is presented.