Zagadnienie prognozowania trwalosci samochodowego silnika spalinowego

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Zagadnienie prognozowania trwalosci samochodowego silnika spalinowego

Niewczas, A. / Drozdzel, P.

The state of piston-cylinder assembly determines technical conditions of the whole engine. Piston-cylinder assembly clearance (calculated as a difference of the cylinder liner outside and inside diameter) can be used as an indicator of its technical state. The systematic growth of piston-cylinder assembly clearance during the operation of the engine is related to the tribological wear taking place mostly on bearing surface of the cylinder liner. The wear process depends on many random factors including the properties of construction material, non-recurrence, variation of production accuracy, differences in production batches, applied operating fluids and changeable service conditions. For the forecasting the car combustion durability, some stochastic models of the tribological wear of piston-rings-cylinder assembly elements have to be taken into account. The comprehensive results of long-term studies on the diesel engine operation and their production quality were presented. In particular, the diesel engines 359M and 4CT90 (rated power 110 kW and 63.5 kW, respectively) used in Polish STAR and LUBLIN trucks were tested for durability and reliability under standard, supervised and forced operational conditions, as well as on a test stand during their start-up. The start-up wear of 359M cylinder increased from 6.4 micrometer to 7.6 micrometer after 1000 start-ups with the decreasing the start-up temperature from 60 deg C to 10 deg C. The 4CT90 cylinder showed a wear of 0.51 micrometer at 75 deg C and 3.4 micrometer at 18 deg C under similar test conditions. The forecasted mileage of the trucks were 600000 km and 800000 km, respectively.