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Next-Generation Fluid Technology for CVT and AT
Technical Paper
2011-01-2122
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Globally, greater emphasis has been placed on vehicles to reduce carbon dioxide emission and fuel consumption. In light of this, Original Equipment Manufacturers (OEMs) have been developing various automatic transmissions such as the step automatic transmission (AT) and the continuously variable transmission (CVT) to improve both fuel consumption and drivability.
Step AT and belt-CVT's are very popular with Japanese OEMs and in particular, recent market trends show CVT use is expanding rapidly due to its potential for improved fuel efficiency. Since the fluid performance requirements for both AT's and CVT's are different depending on transmission design, AT and CVT fluids are currently used separately, with no single fluid technology currently available on the market. The desire for high belt-pulley capacity has driven studies concentrating on metal-on-metal friction for the development of CVT fluids, whereas the desire for anti-shudder durability has been the primary driver for ATF development. As those parameters are typically trade-offs, it is very difficult to achieve both in one fluid.
We herein report on the development of new fluid technologies that show high metal-on-metal friction coefficient with good anti-shudder durability and higher static friction coefficient. As such, the authors were able to develop a Next-Generation Fluid Technology for both CVT and AT applications. The technology has been developed by understanding the function and activity of each component, while further enhancing our understanding of the control of the friction characteristics of the fluid. This enabled the optimization of the whole formulation designed for both CVTF and ATF performance in the areas mentioned above.
Benchmark studies such as static and dynamic friction coefficient in SAE No.2 (JASO 348:2002), anti-shudder durability in LVFA (JASO M349:2001), metal-on-metal friction coefficient in the Block on Ring (JASO M358:2005) and SRV, Shell-4-ball (ASTM D2783), Foaming (ASTM D892), Oxidation stability (JIS K2514)… etc. were carried out in order to confirm the applicability of our fluid technology to Japanese CVTF and ATF applications. Based on the benchmark results, our developed fluid technologies are applicable for both CVTF and ATF performance applications.
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Shrestha, K., Kota, I., Takahiro, N., and Masami, F., "Next-Generation Fluid Technology for CVT and AT," SAE Technical Paper 2011-01-2122, 2011, https://doi.org/10.4271/2011-01-2122.Also In
References
- Morgan, C. Fewkes, R. Marty, S. D. “Development of a Belt CVT Fluid Test Procedure Using the VT20/25E Belt Box for the DEX-CVT® Specification” SAE Paper No. 2002-01-2819
- Shrestha, K. S. Fuji, T. “Study of Friction Material with Friction Fillers for Better Friction Performance in Slipping Clutch System” JAST Tribology Conference 2005
- Shrestha, K. S. Fuji, T. Maruo, K. “ATF Influence on Slipping Control System for Wet Friction Materials” The 2005 International Symposium on the Tribology of Vehicle Transmissions 13 16 18 th Feb 2005 Tsukuba, Japan
- Kaneko, H. Kugimiya, T. Kuribayashi, T. Arai, H. Honda, A. Akiyama, S. “Development of CVTF for steel pushing V-belt CVT” The 2001 International Symposium on the Tribology of Vehicle Transmissions 87 Feb 2001 Toyota, Japan
- Yamazaki, M. Kato, Y. Nakahara, T. Ichihashi, T. “Research on Improvement of Transmission Efficiency by Improving Friction Coefficient Between Element and Pulley of the Belt CVT” JSAE 20084972 2008
- Suzuki, A. Shimizu, K. Kurosawa, M. Saitou, T. Asano, H. “Development of New Xtronic CVT for middle class vehicle” SAE Paper No. 2005-08-0039 JSAE 20055134
- Tsukuda, K. Taniguchi, T. Tsukamoto, K. Tsuduki, S. Hattori, M. Takemoto, K. Habuchi, R. “Toyota's New Belt-drive Continuously Variable Transaxle for 1.3-liter FWD cars” SAE Paper No. 2006-01-1305
- Yamaguchi, M. Ootaki, M. Ito, K. Nirasawa, H. Totsuka, H. “Torque Converter-type High Fuel Economy CVT for Small Passenger Vehicles” SAE Paper No. 2009-01-1541
- Tersigni, S. H. Saathoff, L. D. Cleveland, C. S. Tang, H.-Z. Jones, M. S. Yatsunami, K. “A New Automatic Transmission Fluid with Extended Friction Durability and Minimal Temperature Dependence” SAE Paper No. 2008-01-1728
- Yamamori, K. Saitou, K. Yasushi, K. Ogawa, A. “Development of New Automatic Transmission Fluid for Fuel Economy” SAE Paper No. 2003-01-3258
- Kurihara, I. Kurosawa, O. “Design and Performance of Low-Viscosity ATF” SAE Paper No. 2007-01-3974
- Abraham, W. D. Lann, P. L. Ikeda, M. Tipton, C. D. “Future Automatic Transmission Fluids Now! The Melding of New Technology with Global OEM Needs” SAE Paper No. 2007-01-3975
- Sato, T. “Trends of metal pushing V-belt CVT fluid” JSAE 20074558 2007
- Friction characteristics test method for automatic transmission fluids
- Road vehicles - Test method for anti-shudder performance of automatic transmission fluids
- Standard test method for metal on metal friction characteristics of belt CVT fluids
- JPI-5S-32: Test method for wear preventive characteristics of lubricating fluid
- ASTM D892: Standard test method for foaming characteristics of lubricating oils