Reduction of Friction Losses by Local Management of the Oil Temperatures
In the development stage, the lubrication system of a combustion engine has to be designed for operating points of highest load and speed. But the customer-relevant operation is dominated by moderate loads and speeds. It can therefore be concluded to reduce the friction losses in hydrodynamically dominated journal bearings such as the crankshaft by a lower oil viscosity due to local oil temperature increase in operating points of partial load. However, it must be ensured that mixed friction after speed or load increase does not rise critically.
Within the aspiration to reduce the fuel consumption and emissions of vehicles driven by combustion engines, the reduction of engine-out emissions and the increase of the total efficiency are fundamental approaches. Conventional passenger cars are operated mainly in lower partial loads most of their lifetime. Under these conditions, oil temperatures which are far below the maximum allowed, dominate inside the journal bearings....
The research project "Reduction of friction losses by local management of the oil temperatures" (project number 18419 N/1) was financially supported by the Federal Ministry of Economics and Energy (BMWi) via the Federation of Industrial Research Associations AiF (IGF number 18419). The authors thank for the financial support and also for the support by the working group during the project within the FVV which was leaded by the Chairman Dr. U. Lehmann (Federal-Mogul Wiesbaden GmbH).