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![Schematischer Reibkraftverlauf, modifiziert nach [5]](publication/354152634/figure/fig4/AS:1061282543321109@1630040884545/Schematischer-Reibkraftverlauf-modifiziert-nach-5.png)
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![Stribeck-Kurve, modifiziert nach [4]](publication/354152634/figure/fig1/AS:1061282543321101@1630040884272/Stribeck-Kurve-modifiziert-nach-4_Q320.jpg)
![Schematischer Reibkraftverlauf, modifiziert nach [5]](publication/354152634/figure/fig4/AS:1061282543321109@1630040884545/Schematischer-Reibkraftverlauf-modifiziert-nach-5_Q320.jpg)
Zusammenfassung
Für die Realisierung der in Paris definierten Klimaschutzziele wird die Optimierung des Verbrennungsmotors weiterhin eine tragende Rolle spielen. Sowohl für den Kleinmotor im Hybridantrieb als auch für den Großmotor in Nutzfahrzeugen und Baumaschinen hat eine Effizienzsteigerung höchste Priorität. Maßnahmen zur Reduktion der mechani...
Citations
... In an internal combustion engine operating with variable speed and load, the oil film thickness h min is not a constant value and depends directly on the oil viscosity h dependent on temperature, the relative speed u w of the lubricated surfaces and inversely proportionally to the loading force N (engine load) according to the relationship [24]: (2) where: C -coefficient depending on the dimensions of the coupling elements. ...
Wykazano, że podstawowym zanieczyszczeniem powietrza wlotowego do silnika jest pył drogowy, którego głównym składnikiem jest pył mineralny naniesiony z okolicznych obszarów, gdzie generowany jest przez działanie pojazdów terenowych, maszyn roboczych oraz maszyn rolniczych. Wykazano, że dwa podstawowe składniki pyłu mineralnego krzemionka (SiO2) i korund (Al2O3), których udział w pyle dochodzi do 95%, mają jednocześnie największą twardość, co decyduje o zużyciu elementów silnika. Wykazano, że największe zużycie dwóch współpracujących tarciowo powierzchni powodują ziarna pyłu o rozmiarach równych w danej chwili grubości filmu olejowego. Wykazano, że wszystkie ziarna pyłu o rozmiarach ziaren powyżej 1 m powodują przyspieszone zużycie dwóch współpracujących elementów, jednak największe zużycie powodowane są przez ziarna z zakresu 5÷20 m. Przedstawiono wpływ nadmiernego zużycia skojarzenia tłok-pierścienie tłokowe-cylinder (T-P-C) silnika, wynikającego z rzeczywistej eksploatacji pojazdów oraz badań stanowiskowych na spadek ciśnienia sprężania, intensywność przedmuchu spalin do miski olejowej i moc silnika. Wykazano, że podstawowym składnikiem zanieczyszczeń oleju jest pył mineralny, który przenika z powietrza wlotowego do oleju znajdującego się na powierzchni tulei cylindrowej, skąd pierścienie zgarniają go do miski olejowej. Omówiono wpływ cząstek pyłu na zużycie erozyjne sprężarki i turbiny w urządzeniu doładowującym silnika. Przedstawiono wyniki badań empirycznych wpływu osadzania się ziaren pyłu mineralnego i oleju na elemencie pomiarowym przepływomierza powietrza na zmianę wartości generowanego napięcia wyjściowego będącego miarą strumienia powietrza płynącego do silnika.
... Energies 2022, 15,1182 10 of 52 greater than the particle size dp, there is no contact between the dust grains and the mating surfaces and they do not cause damage to the surfaces. In an internal combustion engine, which operates with variable speed and load, the oil film thickness hmin is not a constant value and depends directly proportional to the oil viscosity depending on the temperature, relative speed in the lubricated surfaces and inversely proportional to the loading force N (engine load) according to the relation [80]: In an internal combustion engine, which operates with variable speed and load, the oil film thickness h min is not a constant value and depends directly proportional to the oil viscosity depending on the temperature, relative speed in the lubricated surfaces and inversely proportional to the loading force N (engine load) according to the relation [80]: ...
... Energies 2022, 15,1182 10 of 52 greater than the particle size dp, there is no contact between the dust grains and the mating surfaces and they do not cause damage to the surfaces. In an internal combustion engine, which operates with variable speed and load, the oil film thickness hmin is not a constant value and depends directly proportional to the oil viscosity depending on the temperature, relative speed in the lubricated surfaces and inversely proportional to the loading force N (engine load) according to the relation [80]: In an internal combustion engine, which operates with variable speed and load, the oil film thickness h min is not a constant value and depends directly proportional to the oil viscosity depending on the temperature, relative speed in the lubricated surfaces and inversely proportional to the loading force N (engine load) according to the relation [80]: ...
... Most of the dynamic clearances are in the range of 0-20 µm. In an internal combustion engine, which operates with variable speed and load, the oil film thickness hmin is not a constant value and depends directly proportional to the oil viscosity depending on the temperature, relative speed in the lubricated surfaces and inversely proportional to the loading force N (engine load) according to the relation [80]: ...
This paper systematically reviews the research progress in the field of the influence of air pollutants in the engine inlet on the accelerated wear of the elements of the association: piston, piston rings, cylinder liner (P-PR-CL), and plain bearing (journal–panel). It was shown at the outset that the primary component of air pollution is road dust. Its main components are dust grains of hard minerals (SiO2, Al2O3), which penetrate the oil film area between two frictionally mating surfaces causing their abrasive wear. Therefore, the effect of three dust parameters (grain size and hardness, and dust concentration in air) on the accelerated wear of the friction pair: piston, piston rings, cylinder liner(P-PR-CL), and plain bearing (journal–pan) is presented extensively. It was noted that the wear values of the same component were obtained by different researchers using different testing techniques and evaluated by different indices. It has been shown that the greatest wear of two frictionally cooperating surfaces is caused by dust grains with sizes equal to the thickness of the oil film at a given moment, which in typical combustion engine associations assumes varied and variable values in the range of 0–50 µm. The oil film thickness between the upper ring and the cylinder liner varies and depends on the crankshaft rotation angle, engine speed and load, and oil viscosity, and takes values less than 10 µm. It was shown that the maximum wear of the cylinder liner, resulting from the cooperation with the piston rings, occurs in the top dead centre (TDC) area and results from unfavorable (high temperature, low piston speed) operating conditions of these elements. From the extensive literature data cited, it follows that abrasive wear is caused by dust grains of specific dimensions, most often 5–20 µm, the greater the wear the greater the hardness of the grains and the sulfur content of the fuel. At the same time, it was shown that the main bearing, crankshaft bearing, and oil ring experienced maximum wear by a different range of particle size, respectively: 20–40, 5–10, and 20–80 μm. It was shown that the mass of dust that enters the engine cylinders and thus the wear of the components is determined by the concentration of dust, the value of which is definitely reduced by the air filter. However, it was pointed out that the low initial filtration efficiency and the presence of large dust grains in the purified air in the initial period of the filter operation (after replacement of the filter element with a new one) may have an impact on the accelerated wear of mainly (P-PR-CL) association. The next stage of the paper presents the effects of excessive wear of the cylinder liner and piston rings of the engine, resulting from actual vehicle operation and bench tests on the decrease in compression pressure and engine power, increase in the intensity of exhaust gas blow-by into the oil sump and increase in oil consumption and exhaust gas toxicity. This paper addresses the current problem of the effect of engine inlet air contaminants on the performance of the air flow meter, which is an essential sensor of the modern internal combustion engine. The phenomenon of deposition of contaminants (mineral dust, salt, carbon deposit, and moisture) on the measuring element (wire or layer anemometer) of the air flow meter has been analyzed. The empirical results presented show that the mineral dust layer on the measuring element of the air flow meter causes a 17.9% reduction in output voltage, and the dust and oil layer causes a 46.7% reduction in output voltage. This affects the decrease in engine power and exhaust toxicity.
Liquid e-fuels such as methanol represent a possible solution to emission-neutral drivetrains. Reduced emissions from the combustion process increase the influence of cylinder wall interaction of the fuel spray and the influence of the fuel ingress into the lubricating oil. Combining emission analysis methods and optical measurements allows a deeper understanding of the processes around the piston assembly group and cylinder wall. This paper aims to increase the understanding of the processes resulting from fuel spray and cylinder wall interaction. Emission measurements from a single-cylinder SI research engine were gathered across multiple operating parameters. Optical measurements were taken at similar operating points using an optically accessible engine. A laser-induced fluorescence (LIF) setup with dyed fuel was used for the optical measurements. This paper focuses on thermodynamic steady state measurements at 2000 rpm, varying loads between 3 and 11 bar IMEP, and corresponding optical measurements at 11 bar IMEP. The measurements of both engines were correlated, and a more profound understanding of the processes involved and their influence on emission behavior was derived. Measurements showed a lower particle emission behavior with a tendency of a higher PN 10 to PN 23 ratio and higher formic acid emissions using methanol fuel compared to gasoline. A higher wall film interaction with methanol could be visualized, and possible effects were correlated to the exhaust emission measurements. Tests with two start of injection timings (SOI) of 430° crank angle (CA) after fired top dead center, as used for gasoline operation, and 550°CA as an optimized SOI for methanol operation were compared. A correlation between the results from the thermodynamic engine and the optically accessible engine was demonstrated. The optical measurements showed lower penetration depths for the optimized SOI and lower fuel spray-to-piston interaction. The thermodynamic measurements have shown higher efficiencies and fewer emissions for the optimized SOI.
Internal combustion engines are increasingly regulated in regard to efficiency and environmental impact, which requires advanced optimization strategies of engine components. The contact between the top ring and the cylinder liner is critical to the efficiency of an internal combustion engine. As shown in a previous study, an amorphous carbon coating can greatly improve the friction properties of piston rings. This work expands on these results by fabricating laser‐interference‐induced microchannels on the coating perpendicular to the direction of movement with a mean depth of 0.97 and 3.13 μm spatial period to further optimize the tribology. Fired single‐cylinder engine measurements of the microtextured rings show a significant reduction in mean piston assembly friction of 5% for operation points that are relevant for urban transportation and up to 10% for specific operation points. Subsequent multibody elastohydrodynamic simulations prove that measured friction changes result from the compression ring microtexture. In particular, the microtexture increases the hydrodynamic pressure, reduces hydrodynamic losses, and leads to 20% lowered compression ring losses for an entire combustion cycle of the investigated operation point. In the future, such tribological concepts can be deployed in internal combustion engines that are powered by sustainable hydrogen or methanol.
div class="section abstract"> The further increase in the efficiency of heavy-duty engines is essential in order to reduce CO2 emissions in the transport sector. This is also valid for the future use of alternative fuels, which can be CO2-neutral, but can cause higher total costs of ownership due to higher prices and limited availability. In addition to thermodynamic optimization, the reduction of mechanical losses is of great importance. In particular, there is a high potential in the piston bore interface, since continuously increasing cylinder pressures have a strong influence on the frictional and lateral piston forces. To meet these future challenges of increasing heavy-duty engine efficiency, AVL has developed a floating liner engine for heavy-duty applications based on its tried and tested passenger car floating liner concept. This article describes the concept of the friction single-cylinder engine developed to measure both the frictional forces and the lateral forces that occur between the piston assembly and cylinder liner during fired engine operation. Four force sensors convert the floating movement of the liner group into the corresponding frictional force. Due to the crank angle based measurement, a very detailed analysis of measures to increase mechanical efficiency of the piston bore interface is possible. In addition, the frictional power can be derived and used to evaluate the CO2 potential of the technologies investigated. The design of the single-cylinder engine has a high degree of flexibility to enable quick component changes and the use of different cranktrains. In a first study, a variation in the crankshaft offset and the potential of this measure to increase engine efficiency are investigated. The results show a clear influence of the cranktrain geometry on the lateral piston force and also on the frictional force during the upstrokes and downstrokes. This measurement campaign confirms the possibilities of the system to contribute to the development of future highly efficient heavy-duty engines.
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