Wyniki wyszukiwania - BazTech

1

Distribution of ring pressure over a worn cylinder liner surface

Serdecki W., Krzymień P.

Combustion Engines

|

2015

|

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 The conclusions withdrawn from these analyses were applied to exemplary calculations that try to evaluate the effect of cylinder deformation on correct collaboration of ring and liner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

Analysis of ring pressure distribution on a deformed cylinder face

Serdecki W.

Journal of Polish CIMAC

|

2012

|

Vol. 7, no 1

219-226

EN

Elastic properties of correctly designed piston compression ring should provide full contact of ring face and the cylinder surface. Actually, because of various phenomena and processes experienced during engine assembly and operation an initially cylindrical liner is being subjected to wear and deformations which eventually affects that contact and cause formation of slots distributed along the cylinder circumference. Following paper describes the most often met deformations of cylinder and presents an evaluation of their influence on the process of compression ring collaboration with the surface of misshaped cylinder. Mathematical relations that allow to calculate the change of ring cylinder pressure and location of areas where blow-by can occur have been presented as well. The presented analyses were supplemented with charts illustrating changeability of certain quantities characteristic for ring and liner construction, using a marine engine ring as an example. The relations established during investigation will be used for a construction of mathematical model of phenomena accompanying the operation of piston-cylinder assembly elements, in the subject of blow-by in particular.

3

Distribution of piston compression ring pressure against the deformed cylinder wall

Serdecki W., Krzymień P.

Silniki Spalinowe

|

2011

|

R. 50, nr 2

17-24

EN

The following study presents typical cylinder deformations that come up during engine assembly and operation and provides results of analysis of how these changes affect the operation of the compression ring. Special attention has been paid to the effect of cylinder diameter increase on the distribution of the circumferential wall pressure and the cause of light gaps formation has been explained. The analyses presented in the following paper have been carried out using a computer program that has been formulated based on a compression ring mathematical model. Exemplary results of simulation have been obtained for a medium speed generator engine of a cylinder diameter of 0.48 m.

PL

W opracowaniu opisano typowe deformacje cylindra pojawiające się podczas montażu i eksploatacji silnika oraz przedstawiono wyniki analizy wpływu tych zmian na pracę pierścienia uszczelniającego. W szczególności omówiono wpływ wzrostu średnicy cylindra na rozkład obwodowego nacisku pierścienia oraz wyjaśniono przyczyny powstawania tzw. szczelin świetlnych. Prezentowane w opracowaniu analizy przeprowadzono przy wykorzystaniu programu obliczeniowego powstałego na podstawie modelu matematycznego uszczelniającego pierścienia tłokowego. Zaprezentowane w artykule przykładowe wyniki symulacji uzyskano dla agregatowego silnika średnioobrotowego o średnicy cylindra równej 0,48 mm.

4

Analysis of relations between the compression ring characteristic parameters

Serdecki W.

Journal of Polish CIMAC

|

2011

|

Vol. 6, no 2

171-180

EN

A proper design of compression ring secures its correct and long term operation. A good ring contact to cylinder wall along the whole circumference with the required distribution of circumferential pressure at the same time are symptoms of this correctness. The analytical methods and more often numerical ones are applied when designing piston rings. A characteristic parameter most often designated as K, which facilitates the comparison of different ring designs and allows for anticipation of its elastic properties is used at the stage of ring design. The following study presents the most significant mathematical relations between the ring geometry and forces that are acting on ring, and shows that results of force operation could differ relative to the point of their application. Relations between the tangential force and the circumferential one have been established as well. For three compression rings verifying tests consisting in definition of selected parameters using analytical and numerical methods have been carried out. The analysis of attained results and trials on explanation of noticed discrepancies are presented in the study as well.

5

Determination of compression ring wall pressure distribution

Serdecki W.

Journal of Polish CIMAC

|

2010

|

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.

6

Compression rings of low-speed high power engines

Serdecki W., Krzymień P.

Journal of KONES

|

2010

|

Vol. 17, No. 4

415-422

EN

The paper describes the design of compression rings used in low-speed, high power marine engines and it analyses relations between the most important operational parameters. Ring material, dimensions, geometry of sliding surfaces, distribution of circumferential pressure as well as operational conditions (thermal and mechanical loads, way of lubrication) were taken into consideration for the analysis mentioned above. Moreover, the paper points at modifications in ring geometry that have been happening for last years, comparing previous and recent designs. The effect of ring circumferential pressure against liner on the piston-cylinder assembly operation has been considered and the causes of its variability have been pointed out as well. When presenting the methods of measurement and tangential force calculations basic advantages and disadvantages have been presented as well as the evaluation of changes resulting from the ring circumferential wear. The compression ring mathematical model developed by the authors allows for a precise definition of relations between ring geometry and distribution of ring circumferential pressure. A need for a more accurate method of ring circumferential pressure evaluation has been justified in summary, giving hints necessaryfor its preparation.

7

Model investigation of piston ring-cylinder liner collaboration on a high power engine

Serdecki W., Krzymień P.

Journal of KONES

|

2009

|

Vol. 16, No. 4

407-413

EN

Failures caused by improper collaboration between piston ring and cylinder liner still happen on engines ofhigh output, marine ones in particular. Among causes of this phenomenon one can mention higher mechanical and thermal loads of crank mechanism as well as difficulties in supply and distribution of lubricating oil over the entire surface of cylinder liner. It would be extremely difficult and because of regulations in most cases impossible to perform tests on correct collaboration between rings and liner of real running engine and on the other hand such tests on a test stand would be quite expensive. Use of mathematical models and tests on simulation model stands offers a way to reduce these costs. Basic dependences connecting piston ring geometry with oil film parameters and introductory results of computations performed with the use of analytical model of test stand will be presented in this paper. The tests are to be carried out for ring geometry corresponding to that of marine engine rings. Due to that, using presented earlier formulas and computer program constructed by the authors the phenomena accompanying operation of different versions of rings were analyzed from the point of oil film thickness and generated friction losses. These ring versions which revealed the most advantageous properties will be made and tested on a test stand.