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1

Distribution of ring pressure over a worn cylinder liner surface

Serdecki W., Krzymień P.

Combustion Engines

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2015

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R. 54, nr 2

53--63

EN

A trial to define the effect of changes in cylinder geometry on compression ring pressure distribution has been presented in this paper which refers to the earlier papers of the authors. The analysis encompasses these cylinders where both circumferential and axial deformations occurred, relative to constructional and assembly errors but above all to engine operation. The conclusions withdrawn from these analyses were applied to exemplary calculations that try to evaluate the effect of cylinder deformation on correct collaboration of ring and liner and particularly on possibility of circumferential gaps leading to blow-by. The drafts presented in the paper show exemplary results of ring pressure distribution for a complete ring path between the dead centers and selected engine operational data. Moreover, such areas of cylinder surface were shown where slots between compression ring and cylinder liner might occur with high probability.

PL

W niniejszym opracowaniu, wiążącym się tematycznie z wcześniejszymi publikacjami autorów, dokonano próby określenia wpływu zmian geometrii cylindra na rozkład nacisku uszczelniającego pierścienia tłokowego. Analizami objęto cylindry, w których wystąpiły zarówno obwodowe, jak i osiowe zmiany kształtu, spowodowane np. błędami konstrukcyjnymi i montażowymi, ale przede wszystkim związane z eksploatacją silnika. Wynikające z tych analiz wnioski wykorzystano do przykładowych obliczeń, obejmujących ocenę wpływu deformacji cylindra na poprawność współpracy pierścienia z gładzią cylindra, a w szczególności na możliwość pojawienia się szczelin obwodowych, ułatwiających wystąpienie przedmuchów gazów. Na zamieszczonych w opracowaniu wykresach pokazano przykładowe wyniki obliczeń rozkładu nacisku pierścienia na gładź cylindra, obejmujące całą drogę pierścienia pomiędzy punktami zwrotnymi, dla wybranych parametrów pracy silnika spalinowego o ZS. Wskazano również obszary położone na gładzi cylindra, w których występuje duże prawdopodobieństwo pojawienia się szczelin pomiędzy gładzią cylindra a powierzchnią ślizgową pierścienia uszczelniającego.

2

Dependence of piston ring parameters determination accuracy on the method of calculation

Serdecki W., Krzymień P.

Journal of KONES

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2011

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Vol. 18, No. 4

435-441

EN

Mathematical models are commonly used at the stage of piston ring design and during examination of ring collaboration with liner surface. Both analytical and numerical methods are used for development of such models. In the case of models based on analytical methods the range of their application is usually limited only to selected cases while the use of numerical methods allow to widen the range of their applications but their accuracy depends on increment used. The paper presents a procedure of verification of the piston ring mathematical model constructed by the authors using numerical methods. Conformity between the results obtained using this program and the results of analytical calculations concerning the displacement of ring free ends brought about by the acting loads was the aim of the analysis. Exemplary computations were carried out for three compression rings of different geometry. Regarding the conformity of achieved results as satisfactory for practical use probable causes of observed discrepancies were pointed out. Relations between energy accumulated in curved bar and loading force (according to the Castiliano's theorem) were used in a course of calculations. Exemplary calculations were carried out for compression rings of three types engine, i.e. automotive, bulldozer and marine ones. A probable cause of differences between results of calculations carried out according to various analytical methods have been pointed out assuming their accuracy as satisfactory for practical purposes.

3

Determination of compression ring wall pressure distribution

Serdecki W.

Journal of Polish CIMAC

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2010

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Vol. 5, no 1

171-178

EN

On a correctly designed engine piston-cylinder assembly the contact of ring and bore should take place through a layer of oil, called oil film. In order to obtain a continuous oil film a proper lubricating oil should be introduced into the region of node elements collaboration, sliding surfaces should have adequate geometry and parameters of collaboration should be chosen suitably. The ring pressure against the liner is one of important quantities that affect formation of oil film. Selection of ring pressure circumferential distribution is pretty complex and depends on a number of factors and changes along the engine life. Presented paper discuss the methods of ring pressure distribution along its circumference and indicate problems connected with measurements. Moreover, basic assumptions used for construction of compression ring mathematical model as well as results obtained using that model were presented for full and partial loads. A need for the construction of computational program that could take into consideration evenly worn and distorted bore surface have been validated as well.