Abstract A Lock-Up clutch is installed inside a Torque Converter to improve fuel efficiency. The Lock-Up facing generates heat, and the temperature of the friction surface rises during Slipping Lock-Up. The temperature must be maintained below the acceptable level for ATF (Automatic Transmission Fluid). Therefore, a prediction technics is required at the development stage. Heat flow analysis by CFD (Computational Fluid Dynamics) has been conducted to predict the temperature of the Lock-Up clutch friction surface. In this paper, the target is a Torque Converter with multi plate Lock-Up clutch. An appropriate boundary condition was applied to the flow simulation in order to set the correct total flow rate in the torque converter, and by verifying analysis results, it is confirmed that the prediction of friction surface temperature is close to the data from the experiment. In addition, it is realized that the flow rate has great influence on the temperature of friction surface. Therefore, the analysis which changes the circulation flow rate gradually has been conducted in order to research the magnitude of flow rate effects to the temperature of the friction surface. As a result, it was confirmed that the relation between flow rate and temperature is not in proportion, but at lower flow levels, an increase in the flow results in a greater temperature change than at higher flow levels. From the above, CFD analysis of friction surface temperature during Slipping Lock-Up has led to an accurate prediction, and it has also clarified the influence of flow rate on the facing temperature.Introduction One of the most urgent and important tasks around the world, is to respond the global warming. This results in technical development to improve the fuel efficiency in various fields of the Auto industry. The Torque Converter industry is seeking methods to gain greater efficiency in transmission of power between the engine and the transmission. Expanding the Lock-Up clutch range is one of the technics for the improvement of fuel efficiency. Engaging the Lock-Up clutch fitted inside the Torque Converter connects the input shaft and output shaft to transmit the power, bypassing the hydrodynamic fluid coupling. The losses due to the fluid torque path would be reduced by using this method, and also it leads the improvement of fuel efficiency. Recently, there is a trend of expanding the Lock-Up range. For further expanding the Lock-Up range, the clutch is slipped. One of the ways to improve this capability is the use of a multi plate Lock-Up clutch, and seeking the improvement of fuel efficiency by using more clutch slip to expand the lock up range. Use of slipping in the long term generates heat; the oil temperature must be maintained at an acceptable level for ATF (Automatic Transmission Fluid). It is important to predict the temperature at the design stage, but it is not easily achieved because of the complicated mechanism of the heat dissipation from Lock-Up clutch. The heat transfer is greatly affected by the flow of ATF [ 1]. Moreover experimental measurement is difficult because Lock-Up clutch is located inside the packaged Torque Converter.Analysis of Temperature Prediction of Friction Surface over Multi Plate Lock-Up Clutch for Torque Converter2014-01-1750 Published 04/01/2014 Yuya Kishi Exedy Corporation, Ltd. Nobuyuki Oshima Hokkaido Univ. Shinji Fujimoto and Tomohiro Tasaka Exedy Corporation, Ltd. CITATION: Kishi, Y., Oshima, N., Fujimoto, S., and Tasaka, T., "Analysis of Temperature Prediction of Friction Surface over Multi Plate Lock-Up Clutch for Torque Converter," SAE Technical Paper 2014-01-1750, 2014, doi:10.4271/2014-01-1750. Copyright © 2014 SAE InternationalDownloaded from SAE International by University of Wisconsin - Madison , Saturday, September 08, 2018In addition, surrounding environment greatly influences the temperature and it makes the analysis of a partial model around the clut