Search Results

Engine running tests and excitation tests were performed to reveal the vibration behavior in a turbocharger-exhaust system related to the turbocharger's operating sound. The operating sound was caused by the resonant vibration excited by the unbalanced inertia force of the rotor. The turbocharger-exhaust system had six resonant frequencies in the operating speed range of the rotor. At resonant speeds, the whole turbocharger was translating or rotating due to bending and torsional deflection of the exhaust manifold. Based on the test results, the vibration behavior could be well simulated by a rigid body-spring model with six degree of freedom. Furthermore, the model was used to analyze the relation between the stiffness of the exhaust manifold and the vibration level. Increasing the stiffness of the exhaust manifold was effective in sufficiently reducing the vibration and sound.

The whirl noise on turbochargers is generated by the self-induced vibration of the oil film in the bearing system. The noise is characterized by its frequency behavior that doesn't increase proportionately to the turbo shaft speed. It tends to be felt annoying. In this paper, to improve the whirl vibration, a statistical analysis approach was applied to the bearing specifications. The results from experiments showed that the bearing clearances played an important role in the reduction of the whirl vibration. To further investigate into this phenomenon, the shaft oscillation behavior was measured. And a vibration simulation program for the turbocharger bearing system was also developed.