Development of a Compact and High-Performance Torque Converter Based on a New Parameter Sensitivity Mapping

Automatic transmissions are required to obtain higher efficiency and to reduce their size and weight in order to improve environmental friendliness and fuel economy. Especially in the torque converter development process, there is a need to strengthen the torque multiplication capability to compensate driving force in the non-boost region as a result of recent trends toward engine downsizing. At the same time, there are more rigorous space-saving requirements from the standpoint of ensuring vehicle collision safety. To meet these various requirements, a new torque converter has been developed that provides world-class performance in a minimized torus size. The capacity factor and the torque ratio are the two major parameters of torque converter performance. There are many dimensional parameters concerning the blades and cross-sectional shapes of torus that must be considered in the performance design. It is difficult to optimize these parameters because they involve numerous tradeoffs. In this development project, the quantitative sensitivities between each of the parameters were broadly mapped. As a result, it was found that points existed in every parameter combination for optimizing both performance and size. Such points were found in regions away from those widely used previously in torque converter design. This paper outlines the mapping method used in this project and describes the newly developed torque converter.