Abstract
This paper presents a case study to reduce noise radiated from a torque converter newly developed for an automatic transmission assembled to a passenger car. It was realized that the torque converter radiated a pure tone noise bothering drivers in the middle of a developing stage. Then, the torque converter was investigated by measuring noise level and noise characteristics with noise measurement instrument. The pure tone noise was dominating the bothering noise and the overall noise including the pure tone noise was much higher than a design standard. The pure tone noise was shown to be the same as the frequency of multiplication of the number of impeller and torque converter speed. Through fluid dynamic analysis for different numbers of impeller blades, there were a proper number of blades to effectively reduce the noise as low as drivers could not recognize the noise in cabin. Finally, the improved torque converter is in mass-production and being applied to a 1,800~2,000cc engine.
Keywords:Torque Converter, CFD, Vortex, Radiation Sound, Order Tracking