This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Development of Next-Generation Continuously Variable Transmission Fluid Technology
ISSN: 0148-7191, e-ISSN: 2688-3627
Published September 10, 2012 by SAE International in United States
Annotation ability available
Public concern and increasing regulations surrounding environmental issues, such as CO₂ emissions, are making it important for car makers to improve the fuel efficiency of the vehicles they manufacture and sell. A wide array of transmission technologies are being employed towards this end including, but not limited to, 6, 7, and 8 speeds stepped automatic transmissions, dual clutch transmissions (DCT) and continuously variable transmissions (CVT). The number of passenger cars equipped with CVTs has been increasing and push belt CVT types (b-CVT) are widely used. Since engine torque is transferred to the wheels via friction between the steel elements of the belt and the steel pulleys in a b-CVT, having a high metal on metal friction is required. As the CVT fluid is a key part of the CVT system, using a special CVT Fluid (CVTF) is critical in order to provide and maintain the required high metal-on-metal friction performance.
We herein report the development of new CVTF technology which has high metal-on-metal friction that supports improved system efficiency and of a new Low Viscosity CVTF that improves fuel economy. A variety of screening tools including JASO M358-2005 block on ring test and an in-house CVT metal on metal friction test, referred to as the 3-Element Test were chosen and utilized for the validation. The performance of the fluids has been confirmed by measuring the torque capacity in a full-scale CVT belt box tester. Also the wet clutch performance was evaluated using a modified version of the JASO M348-2002 friction test method as well as wear protection by the FZG test and anti-oxidation by Indiana Stirring Oxidation Test (ISOT).
The results of all of the above testing show that these new CVTF technology can meet current and future requirements of CVTs.
|Technical Paper||A Study on Shudder in Automatic Transmission Lock-up Clutch Systems and Its Countermeasures|
|Technical Paper||Transient Flow Field Analysis Around a Lockup Clutch Inside a Torque Converter|
CitationCha, S., Whitticar, D., Gajanayake, A., and Ikeda, M., "Development of Next-Generation Continuously Variable Transmission Fluid Technology," SAE Technical Paper 2012-01-1670, 2012, https://doi.org/10.4271/2012-01-1670.
- Morgan, C. Fewkes, R. Marty, S. “Development of a Belt CVT Fluid Test Procedure Using the VT20/25E Belt Box for the DEX-CVT® Specification,” SAE Technical Paper 2002-01-2819 2002 10.4271/2002-01-2819
- Narita, K. Abe, A. Deshimaru, J. Hara, S. “Improvement of Torque Capacity of Metal V. Belt Type CVT Fluids” SAE Technical Paper 2003-01-1977 2003 10.4271/2003-01-1977
- Pennings, B. van Drogen, M. Brandsma, A. Ginkel, E. et al. “Van Doorne CVT Fluid Test: A Test Method on Belt-Pulley Level to Select Fluids for Push Belt CVT Applications,” SAE Technical Paper 2003-01-3253 2003 10.4271/2003-01-3253
- van der Sluis, F. van Dongen, T. van Spijk, G. van der velde, A. et al. “Efficiency Optimization of the Pushbelt CVT,” SAE Technical Paper 2007-01-1457 2007 10.4271/2007-01-1457
- Kurashina, H. Ito, Y. Isomura, H. Yamaguchi, K. “A Study of Transmission fluid Performance on Fuel Economy,” SAE Technical Paper 2007-01-1980 2007 10.4271/2007-01-1980
- Saito, T. “Application of Stress Simulation under Transient Condition for Metal Pushing V-belt of CVT,” SAE Technical Paper 2008-01-0415 2008 10.4271/2008-01-0415
- van der Noll, E. van der Sluis, F. van Dongen, T. van der Velde, A. “Innovative Self-optimising Clamping Force Strategy for the Pushbelt CVT,” SAE Int. J. Engines 2 1 1489 1498 2009 10.4271/2009-01-1537
- Kobayashi, D. Mabuchi, Y. Katoh, Y. “A Study on the Torque Capacity of a Metal Pushing V-Belt for CVTs,” SAE Technical Paper 980822 1998 10.4271/980822
- Nakazawa, K. Mitsui, H. Kakegawa, K. Murakami, Y. et al. “Performance of a CVT Fluid for High Torque Transmitting Belt-CVTs,” SAE Technical Paper 982675 1998 10.4271/982675
- Japanese Automobile Standard JASO M358-2005 “Standard test method for metal on metal friction characteristics of belt CVT fluids”
- Vermilya, D. Ward, W. “The Development of CVT Fluids with Higher Friction Coefficients,” SAE Technical Paper 2003-01-1978 2003 10.4271/2003-01-1978
- Pennings, B. van Drogen, M. Brandsma, A. van Ginkel, E. Lemmens, M. “Van Doorne CVT Fluid Test: A Test Method on Belt-Pulley Level to Select Fluids for Push Belt CVT Applications” SAE Technical Paper 2003-01-3253 2003 10.4271/2003-01-3253
- Japanese Automobile Standard JASO M348-2002 “Test method for friction property of automatic transmission fluids”
- Yoo, S. Cha, S. Ikeda, M. Nakagawa, I. et al. “Development of Next-Generation Automatic Transmission Fluid Technology,” SAE Technical Paper 2007-01-3976 2007 10.4271/2007-01-3976