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Development of Extremely Flat Torque Converter for Automatic Transmission Systems
Published October 22, 2006 by Society of Automotive Engineers of Japan in Japan
With the reduction in size and weight of automatic transmissions, the allowable size of Torque Converter is also decreasing. In contrast, suitable performance for more powerful engines and increased capacity for absorbing vibration are also required. To satisfy these needs of the market, an Extremely Flat Torque Converter (EFTC) with high capacity fluid performance and Long Travel Damper System (LTDS) have been developed. To use the LTDS, the size of the blades, which is the real factor of power transmission, has been decreased by 40% as compared to the latest ultra-flat models, and the flat ratio (FR) of the blades is 35% less than conventional models. In order to obtain the desired high fluid performance from this extremely flat torque, the core shape turns out to be a key factor, and the controllability of outgoing flow angle influenced by the Pitch/Chord ratio of the reactor blades is also important. Fluid performance is designed by a sensitivity study using the well-known, one-dimensional analysis method and detailed investigation with three-dimensional numerical simulation, and is verified by performance test results of prototypes.