Development of Compact Torque Converter with New Multiple Disk Clutch for Toyota New FWD Eight-Speed Transmission Direct Shift-8AT 2017-01-1118

Increasingly stringent environmental regulations requiring lower CO₂ emissions and higher fuel economy have made it essential to develop vehicles with superior fuel efficiency and cleaner emissions. At the same time, there is growing demand for even more powerful and quieter vehicles. To help satisfy these requirements, Toyota Motor Corporation has developed a new 8-speed automatic transmission for front wheel drive vehicles, incorporating its first compact torque converter with a multiple disk lock-up mechanism. This newly developed compact torque converter with a multiple disk lock-up mechanism was designed under the Toyota New Global Architecture (TNGA) development concept to achieve an excellent balance between higher efficiency through the commonization of components and stronger product appeal through installation on a whole family of transmissions. This compact torque converter is compatible with a variety of engines from inline 4-cylinder to V6 configurations. This transmission also includes a multiple disk lock-up clutch that can be used all through the torque range, which helps create a direct dynamic response and better fuel economy. A new ultra-flat torus was developed with the same stall performance as a torus for a V6 engine but with the same size as the previous inline 4-cylinder engine torus. This torus combines a maximum efficiency of at least 80% with an approximately 12% smaller flow diameter and an approximately 28% flatter design. This paper describes the main design characteristics of the new multiple disk clutch and torus.