Determining Vibro-Acoustic Effects in Multidomain Systems Using a Custom Simscape Gear Library

Due to the increasing electrification of vehicles, the combustion engine is gradually being replaced by high-performance electric machines. Eliminating the acoustical noise generated by the engine exposes other sources of noise, such as gear whine or gear rattle. Within a gearbox, gear mesh excitation is a main source of vibration and can be characterized as parametric, geometric, and impulse excitation. Nevertheless, the vibro-acoustic behavior of an entire drivetrain depends on additional properties and system configurations such as type of electric machine, lubrication, bearing, battery status, heat conduction, and other cross-domain interaction mechanisms. Therefore, in order to predict, analyze, and optimize the vibro-acoustic behavior of a mechatronic drive system, a simulation model spanning multiple physical domains is critical to the product development process.

This presentation provides an overview of how Bosch modeled gear mesh excitation in Simscape™. Radial, tangential, and axial gear forces are calculated within the model. Additionally, the transmission error, which is the deviation between pinion and driven gear, is determined, providing an approximation of noise generation. Since the physical model is implemented as a generic gear model library in Simscape, it can be used for one-dimensional mechanical studies in SimDriveline™ as well as three-dimensional multibody simulations in SimMechanics™. Finally, using the physical network method in Simscape enables Bosch to analyze the effects of gear vibration across physical domains for a wide range of mechatronic systems.