Dynamic Analysis of Damper System in Torque Converter

This paper presents a newly proposed damper system in torque converter to minimize the vibration in powertrain system. The lock-up clutch in torque converter makes engine and transmission connected directly. When the lock-up clutch is engaged, the torque fluctuation of engine is attenuated by the damper system. This function decides the vehicle powertrain dynamic characteristics. To calculate the dynamic characteristics of vehicle, the vehicle model with a six-cylindered diesel engine and eight-speed A/T and three damper systems (conventional damper, turbine damper and new damper system) were structured by using AMESim® that is a commercial S/W. At first, the proposed damper system was analyzed by using the damper spring stiffness of previous damper system. New resonance frequency was appeared around 45Hz which didn't exist in previous damper system. However, this resonance frequency was critical to the dynamic characteristics of the vehicle because engine operation range was between 40Hz and 250Hz. Therefore, this resonance frequency should be excluded from engine operation range. For solving this problem, the stiffness of damper spring was changed by using the stiffness equation proposed by regression analysis. As a result, new resonance frequency could be excluded from engine operation range, and the magnitude of frequency response function of the new damper system was less than that of the previous damper system. The torque and speed fluctuations of the vehicle model with new damper system were also reduced.