Abstract
Changes in engine performance and efficiency, the tightness of ring-pack and wear of piston group parts during long-lasting bench durability test were investigated. The tests were conducted on 2 modern automotive diesel engines. The parameters analysed improved in the initial period of engine operation and then they started to deteriorate gradually; however, the rates of change were different for different parameters. The rate of change was the highest in the case of lubricating oil consumption (100% increase during the test). The blowby increased in that period of time by 25-60%, depending on the condition of engine operation. The changes in power and specific fuel consumption were much smaller – only a few percent. Moreover, using the previously developed method utilizing the simulations made with the use of the ring-pack model, the durability of the piston group was predicted. The predicted durability was equal to 300,000 km.
Highlights
The piston group dictates the tightness of the combustion chamber
After and during the durability test, speed characteristics and other measurements were performed to determine the parameters of the engine including blow-by and oil consumption
The results of the first measurements, made before the durability test (t = 0), were ignored – it was assumed that the improvement in the values of the parameters observed in the first period of engine operation was associated with the run-in of the engines and that the run-in process had finished before the przeprowadzano tzw. próby olejowe
Summary
The piston group dictates the tightness of the combustion chamber. Component wear increases blow-by and oil consumption and so causes a loss of power, energy efficiency and an increase in emissions. The tendency for increasing unit power means that the constituent parts of the piston group are subjected to increasing mechanical and thermal loads, which causes quicker wear. Experience from servicing indicates, that a large increase in the power density affects the wear of more loaded engine parts, and the durability and reliability of whole engines. Before being put into production, engines are subjected to harsh durability tests. In this paper the results of bench durability tests of a car diesel engine are presented. The engine tested was a development version of an engine with power increased by 30% relative to the base version. The results of the piston group durability prediction made with the use of the ring-pack model are presented in the paper
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