Development of a Compact Torque Converter with a New Multiple Disk Clutch for Toyota’s New FWD 8-speed Transmission

Paper #:
  • 2017-01-1118

  • 2017-03-28
Increasingly stringent environmental regulations, such as reducing carbon dioxide emissions and increasing fuel economy targets, have made it essential to develop vehicles with superior fuel efficiency and cleaner emissions. At the same time, the demand for improved vehicle characteristics such as driving performance and NVH are increasing. Toyota Motor Corporation has developed a new eight-speed automatic transaxle (UA80) which has realized these requirements at a high level, and is adopted into the new Sienna and Highlander. UA80 is the first Toyota transaxle which incorporates the TNGA concept. It has high level competitiveness in a wide torque range from L4 engines to V6 engines by using both optimization and standardization of main components. Additionally, UA80 has achieved an increased ease of installation by optimizing the transaxle size and arrangement while still achieving a low gravity center. UA80’s low gravity center contributes to the vehicle’s attractiveness by improving driving performance, NVH and design flexibility. The UA80 Torque Converter is Toyota’s first use of a Multiple Disk Clutch and the smallest torus in this torque range for FWD vehicles. The Multiple Disk Clutch utilizes slip control in all torque ranges of UA80 and it has Highly Accurate and Highly Responsive Lock up Piston Mechanics. As a result, the vehicle can use the Lock up Clutch in any condition and the vehicle driver experiences an improved connection between pedal application and vehicle response and improved the fuel efficiency. To enable packaging of the Multiple Disk Clutch, The New Next Generation Flat Torus has approximately 12% smaller flow diameter and approximately 28% higher flatness than U660. Despite these restrictions, this torus keeps a high torque capacity, and a max efficiency over 80%. This paper describes the major features, adopted techniques and performance of The Multiple Disk Clutch and The New Torus.
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