The ever higher pressures and temperatures in modern engines make combustion increasingly efficient, but also place increasing demands on strength, for example of valves, pistons and camshafts.
Wherever mechanical components move, friction takes place. Friction should usually be kept as low as possible in combustion engines, as it generates heat – i.e. energy that is then lost elsewhere. Moreover, friction leads to increased wear, which can reduce the lifespan of engines and their components. Therefore, design engineers and material developers are also working on minimising friction loss in the powertrain.
As the correct use of operating fluids is a significant influencing factor in the “tribological system”, lubricants such as greases and oils and their viscosity are on the agenda of collective researchers. For instance, friction loss can be reduced through targeted thermal management of the engine oil – a topic that the planning group focuses on in specific projects.
In its research projects, the planning group also works on tribological issues regarding hybrid and electric vehicles, such as tribological fluid models for ancillary units in electrified powertrains. In doing so, FVV researchers are broadening their view of the key questions for the mobility of tomorrow.
Internal deposits in diesel injectors can lead to engine operating problems or a changed dynamic behavior of injectors. Common rail injectors for heavy-duty engines are particularly in focus because of their special requirements. These engines in particular are characterized by applications with the highest rail pressures, a high proportion of high-load operation and fields of application in a wide variety of regions and markets. To avoid loss of performance in current and future injection systems, a laboratory test method for preventive fuel screening with regard to the tendency to build up deposits was developed in a research project from FVV at LKV Rostock and verified with injection bench tests.Read more
In order to be able to design the piston assembly of a combustion engine, knowledge of oil transport in the piston ring is necessary. As the availability of this knowledge is poor, a one-cylinder research engine with complex measuring technology was developed in the project for investigating the tribologic states of the piston assembly. Among others, this measurement technology comprised a measurement lever system integrated into the crankcase as well as processes for determining lubricant viscosity and piston ring rotation. A newly developed simulation model reflected the piston ring package and determined the influencing factors on the oil supply. In this way the blowby (the gas that blows past the piston rings during the compression stroke), the axial ring movement, and the intermediate ring pressure for example can be reliably projected. As the developed flow solver for determining the oil transport is designed for industrial use, users can directly benefit from the project results.Read more
When designing frictionally engaged component joints, such as flange and screw connections for example, precise knowledge of the friction coefficient plays an important role. In addition, torque transmission can be ensured with the help of higher static friction values, which in turn reduces the number of connecting elements and their dimensions. In this project, static friction values were calculated on standardised test stands and geometric parameters derived. The share of friction mechanisms and the friction characteristics of frictionally engaged surface pairings could be shown separately for the first time through simulation. Investigations of PVD (Physical Vapour Deposition) coatings, thermal sprayed coatings and laser structures show that it is possible to significantly increase friction co-efficiency with all three methods. Thus the user has different variations at his disposal, which can be selected based on application-specific criteria. With the project results, the user is capable of designing frictionally engaged component connections with greater resource efficiency in the future.Read more
High power density is key for further increasing the efficiency of internal combustion engines. It can be reached by aligning operating fluids (fuels, coolants and lubricants) and materials to pair long service life and high fatigue strength with optimized friction. The projects initiated
by the Research Association for Combustion Engines (FVV) bridge the gap between basic research and industrial applications.
Projects of Planning group 4 »Strength & Tribology«
Research Association for Combustion Engines eV
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