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.
Development of Next-Generation Continuously Variable Transmission Fluid Technology
Sae Technical Papers
SAE 2012 International Powertrains, Fuels & Lubricants Meeting ; 2012
2012-09-10
Conference paper
English
Development of Next-Generation Continuously Variable Transmission Fluid Technology
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