EcoBoost engines constitute one of the strategies used by Ford Motor Company to deliver engines with improved fuel economy and performance. However, turbochargers exhibit many inherent NVH challenges that need to be addressed in order to deliver refined engines that meet customer’s expectation. One of these challenges is the turbocharger 1st order synchronous noise due to the interaction between the manufacturing tolerances of the rotating components and the dynamic behavior of the rotor.
This paper discusses an MBD/FEA/BEM based method to predict the nonlinear dynamic behavior of the rotor semi floating bearing, its impact on the bearing loads and the resulting powerplant noise due to the interaction with the turbocharger imbalance level. The MBD predictions of the bearing forces from the inner nonlinear hydrodynamic and outer semi floating squeeze damper bearings are used in an FEA/BEM analysis to predict the synchronous of turbocharger housing vibrations level and the synchronous powerplant radiated sound pressure.
Measurement data obtained for three different levels of turbocharger imbalance and for different engine conditions are presented in this paper. This data validates the analytical predictions of the rotor dynamic forces, the turbocharger housing vibrations and the powerplant radiated noise.