Refinement of the Interior Booming Noise Caused by the Lock-up Clutch in Automatic Transmission Vehicle

For the purpose of enhancing the fuel economy in compact cars, it has been tried to expand the lock-up rpm of damper clutch in automatic transmission. But this way is likely to cause the interior booming noise accompanied by the body vibration. It is why lowering the engine rpm, where the damper starts to be locked up is, causes powertrain vibration increases due to the shortage of the engine power needed by the vehicle load. Therefore, in this study, the causes and paths of the booming noise and body vibration coming from expanding the lock-up rpm will be investigated. That is, the following questions are examined. How much the vibration of the powertrain increases, how the vibration of the powertrain transfers and thus, how and how much the interior booming noise increases. Specially, using RMA (running mode analysis) method, the principal vibration path and the resonance of vehicle body will be investigated. Through investigation, this study will propose a few kinds of structural modifications and among those modifications the optimized modification will be adopted as the refinement of the booming noise and the body vibration.