Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE Energy saving in vehicles
Based on analysis of over 100 vehicles by Oak Ridge National Laboratory using EPA Test Car List Data Files, it is reported by U.S. Environmental Protection Agency that estimated energy loss is about 70% in engine, about 5% in parasitic system, 18 to 25% in power to wheels system and 5% to 6% in powertrain, (Fig.2, Ref.4). Report in Handelsblatt Euroforum shows that, by making the same percentage of reduction in weight change, drag coefficients, rolling resistance and energy consumption in powertrain respectively, the best reduction in fuel consumption could be achieved by a reduction in energy consumption in powertrain, (Fig.3, Ref.5). Technologies such as automated manual transmissions (AMTs), double-clutch, lock-up transmissions and continuously variable transmissions (CVTs) can reduce these losses.
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velocity joint (CVJ) systems, all wheel driving (AWD) systems, transmissions and axles (TranAxles) systems and e-Drive systems. As a global business serving the leading vehicle manufacturers, GKN Driveline develops, builds and supplies an extensive range of automotive driveline products and systems with an improved efficiency – for use in the smallest ultra low-cost car to the most sophisticated premium vehicle demanding the most complex driving dynamics.
Tribology in powertrain system Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear. In order to have good performance with enhanced life and improved efficiency, it is essential to understand tribology systems, including system requirements, system designs, materials, surface engineering, surface metrology, movement of parts and service conditions etc.
In GKN transmissions/axles systems and e-Drive systems, the tribology system is mainly working in a regime of full oil film lubrication conditions, (Fig.4). In this regime, two surfaces are fully separated by an oil film. A reduction of oil viscosity could decrease the internal shear force between oil molecules as a result of reducing friction and improving efficiency, (Fig.4). However, after a reduction of oil viscosity, the oil film thickness could decrease as a result of potential risk of surface damage under high pressures. At the same time, a protection of contact surfaces from surface damage becomes an important factor during starting movement in systems. Therefore the use of special additives is required.
Figure 2. Energy comparison during driving, (Ref.4).
Figure 4. Key areas where GKN products perform.
Figure 3. A reduction of fuel consumption in vehicle from different consideration, (Ref.5).
GKN Driveline is the world’s leading manufacturer of automotive driveline systems to deliver optimum solutions accurately engineered to all specifications in powertrain, including constant
In modern CVJ systems, key parts perform in a regime of boundary lubrication conditions because the pressures are up to 8 GPa on the point contact surfaces in ball types of CVJs and 4 GPa on the line contact surfaces in tripod type of CVJs. At such high pressures, contact surfaces could be prevented from wear and cold welding with low friction by selecting proper
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