Wyniki wyszukiwania - BazTech

1

Geometry of the improved layer over a piston skirt

Iskra A., Krzymień P., Wróblewski E.

Combustion Engines

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2015

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R. 54, nr 3

192--196

EN

Geometry of the slot between piston skirt and cylinder bore affects the friction losses of the IC engine to the far extent. It appears that these losses depend more on the area covered with oil than the thickness of oil layer separating collaborating parts. Barrel-shaped or stepwise piston skirt is the way to reduce the oil covered area. The first concept has been used for years while the stepwise profile has not been applied for various reasons, although this idea providing higher load capacity of oil layer in stepwise slot was published in literature in the fifties of twentieth century. The stepwise profile can be obtained covering the cylindrical or taper piston skirt with a thin layer of carbon nanotubes (CNT). This paper presents the results of simulation and test stand investigations leading to the reduction in friction losses and abrasive wear of piston skirt and cylinder bore. Covering the piston skirt with a thin layer of CNT one can get an extremely advantageous tribological properties of the piston assembly which means the expected parameters of oil film and in a case of film rupture – an ignorable abrasive wear of the CNT layer and/or cylinder bore.

PL

Geometria szczeliny między powierzchnią boczną tłoka a cylindrem w bardzo dużym stopniu wpływa na straty tarcia w silniku spalinowym. Okazuje się, że na wymienione straty w większym stopniu wpływa obszar pokryty filmem olejowym niż grubość filmu olejowego rozdzielającego współpracujące elementy. Drogą do zmniejszenia obszaru pokrytego filmem olejowym jest baryłkowy lub schodkowy kształt powierzchni bocznej tłoka. Pierwszy sposób stosowany jest od dawna, natomiast kształt schodkowy z różnych powodów nie był dotychczas stosowany, chociaż publikacje o największej nośności filmu olejowego utworzonego w szczelinie schodkowej ukazały się jeszcze w latach pięćdziesiątych dwudziestego wieku. Kształt schodkowy szczeliny można uzyskać nanosząc cienką warstwę nanorurek węglowych (CNT) na cylindryczną lub stożkową powierzchnię boczną tłoka. W artykule przedstawiono wyniki badań stanowiskowych i symulacyjnych zmierzających do redukcji strat tarcia i zużycia ściernego powierzchni bocznej tłoka i gładzi cylindra. Syntetyzując na powierzchni bocznej tłoka cienką warstwę CNT uzyskuje się bardzo dobre właściwości trybologiczne pary kinematycznej, jaką stanowi zespół tłok – cylinder, co oznacza oczekiwane parametry filmu olejowego, a w przypadku jego braku, prowadzącego do bezpośredniego kontaktu mikro-nierówności tłoka i cylindra - pomijalne zużycie ścierne warstwy CNT i/lub gładzi cylindra.

2

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.

3

Selected applications of carbon nanotubes in construction of internal combustion engine

Kałużny J., Iskra A., Babiak M., Krzymień P., Giersig M., Kempa K.

Journal of Polish CIMAC

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2014

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Vol. 9, no 2

105--116

EN

For over hundred years the internal combustion engine has been applied as the drive of various vehicles and it is continuously improved. The most important requirements that should be satisfied by future engines concern reduction in fuel consumption and exhaust emissions preserving possibly low cost of engine manufacturing. In order to fulfill such demands a concept of so called "downsizing" has been proposed which concept is based on high values of mean effective pressure, and as a consequence high mechanical and thermal loads. Further increase of engine power per liter is still possible but new materials are needed in order to keep the manufacturing costs at the reasonable level. The paper presents an analysis of operational conditions of selected parts of supercharged engines constructed according to the downsizing concept and shows areas where the use of new materials could be most profitable. Results of engine tests carried out using modernized catalytic reactors and pistons in which advantages of the carbon nanotubes unique properties were deliberately taken have been presented in this paper as well. The obtained results allow to conclude that the nanotube layer over the piston skirt offers the friction losses reduction by as much as 16% relative to the whole engine. The observed properties of nanotubes can be profitable in a number of applications indicated in the paper.

4

Analysis of parameters variability of compression ring and cylinder liner collaboration during engine operation

Serdecki W., Krzymień P.

Journal of Polish CIMAC

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2014

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Vol. 9, no 1

121--128

EN

Construction of piston-rings-liner assembly of contemporary engines of low and medium power secures a long time reliable operation. In the case of engines of higher output, e.g. marine and railway ones still occur failures caused by improper collaboration of piston rings and cylinder liner. One can mention variations in collaboration surface and difficulties with supply and proper distribution of lubricating oil over the entire surface of cylinder liner among the most important ones. Changes in value of parameters characteristic for compression ring and cylinder liner collaboration that occur during engine run have been analyzed in the following study. Attention has been paid to the ability of ring contact with the liner, especially those features that cause the formation of light slots between ring face and liner surface. Drafts presented in the paper show the results of compression ring pressure distribution and the geometry of light slots carried out for technical data of the earth moving machine engine. Simulation computations take into account both the effect of engine operation cycle phase and selected stages of its run as well.

5

An analysis of phenomena accompanying ring collaboration with worn cylinder surface

Serdecki W., Krzymień P.

Combustion Engines

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2013

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R. 52, nr 2

40--47

EN

The presented study which refers to the earlier papers of the authors discusses an effect of cylinder wall deformation on the effectiveness of compression ring operation. Presented models permit a mathematical description of a deformed cylinder and definition of ring wall pressure relative to these deformations. The drafts presented in the paper, obtained in a course of calculations of a compression ring installed in a work machine engine, allow to evaluate the effect of cylinder deformations on distribution of ring circumferential pressure and point out areas where the light slots could occur.

PL

W niniejszej pracy, wiążącej się tematycznie z wcześniejszymi publikacjami autorów, określono wpływ zmian kształtu otworu cylindra na skuteczność pracy pierścienia uszczelniającego. Zaprezentowano modele, umożliwiające matematyczny opis odkształconego otworu cylindra, a także wyznaczenie odpowiadającego tym odkształceniom nacisku pierścienia na gładź cylindra. Na zamieszczonych w opracowaniu wykresach, uzyskanych podczas obliczeń pierścienia uszczelniającego pracującego w silniku spalinowym maszyny roboczej, pokazano przebiegi pozwalające ocenić wpływu wartości zniekształcenia otworu cylindra na rozkład nacisków obwodowych, a także wskazano miejsca, w których możliwe jest pojawienie się tzw. szczelin świetlnych.

6

How the wear of cylinder liner affects the cooperation of piston - cylinder assembly of IC engine

Serdecki W., Krzymień P.

Journal of KONES

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2012

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Vol. 19, No. 1

357-363

EN

A ring pack of modern IC engine consists of at least one compression ring that should guarantee secure a necessary tightness of combustion chamber. A circumferential wall pressure of correctly designed compression ring should be sufficient to achieve a full contact between wall and ring, which means light tightness preventing gas blowby. Lack of tightness is being considered as a principal cause of deterioration of engine performance data including torque instability, and a rapid grow in ring and cylinder wear within the area of blow-by. During engine design process mathematical models are applied which implement analytical and numerical methods of calculation. Analytical methods that were used earlier presented a limited range of application and lower accuracy in comparison to the numerical methods but they allowed achieving approximate results quicker. Taking this into consideration the presented study describes the most important relations between ring geometry and its wall pressure, which were obtained using the analytical methods. Presented formulas facilitate the evaluation of cylinder wear effect on the ring circumferential pressure distribution, especially the change in liner diameter. An attempt of light slits evaluation has been performed as well. The study was supplemented with graphs and calculative example.

7

The effect of changes in cylinder liner geometry on the operation of piston compression ring

Serdecki W., Krzymień P.

Czasopismo Techniczne. Mechanika

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2012

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R. 109, z. 3-M

285--294

EN

Presented paper deals with cylinder deformations which could be most often encountered and tries to explain the causes of such situations. The essential part of the paper presents relations which allow to describe cylinder shape of any geometry and the attached example explains better the principles of their application. The obtained relations will be applied to the constructed mathematical model, in particular in a module describing the link between cylinder deformations and blowby during engine run. It should be added that the presented study is a part of a series concerning the collaboration of compression ring with the cylinder wall observed on a running engine.

PL

W niniejszym opracowaniu opisano najczęściej spotykane deformacje cylindra i dokonano próby wyjaśnienia przyczyn ich powstawania. W zasadniczej jego części zaprezentowano związki pozwalające opisać kształt cylindra o dowolnej, złożonej geometrii, a załączony przykład obliczeniowy pozwala lepiej wyjaśnić zasady ich stosowania. U zyskane zależności zostaną wykorzystane w budowanym modelu matematycznym, w module dotyczącym wpływu odkształceń cylindra na przedmuchy gazów spalinowych w czasie pracy silnika. N ależy dodać, że niniejsze opracowanie jest częścią większego cyklu dotyczącego współpracy uszczelniającego pierścienia tłokowego z gładzią cylindra w czasie pracy silnika spalinowego.

8

Distribution of piston compression ring pressure against the deformed cylinder wall

Serdecki W., Krzymień P.

Silniki Spalinowe

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2011

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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.

9

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.

10

Lube oil consumption's impact on environment

Krzymień P.

Journal of KONES

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2010

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Vol. 17, No. 2

265-270

EN

The problem of lube oil consumption has been the point of interest of scientists for years,first because of economy and later - because of stringent standards of environment protection. From the point of economy lube oil consumption is not a problem of modern engines. On the other hand even a brief look proves that there is a quite wide range of admissible consumption from negligible values up to even l litr per 100 km. The question is why this range is so wide. Possible answer is that engine manufacturers leave so wide margin taking into consideration situations of very short trips, mainly in towns, when engine runs not fully warmed up with greater clearances, especially within the piston-cylinder assembly. Any oil consumption results in emission of particulate matter, which conveys a weighty number of hydrocarbons of which the most manifest serious hazardous properties, mainly carcinogenic ones. Nowadays, standards of environment protection require for instance the use of diesel particle filters and the excessive oil consumption could lead to the premature damage of these devices. Correct operation of the DPF could be disturbed not only by the excessive oil consumption but also by the use of improper oil, i.e. the non-low ash one. Certain additives that improve oil properties could produce ash as a result of oil combustion, which could clog filter irreversibly.

11

Compression rings of low-speed high power engines

Serdecki W., Krzymień P.

Journal of KONES

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2010

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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.

12

Tests on piston ring – cylinder liner collaboration of high power engine

Serdecki W., Krzymień P., Brzeziński Ł.

Silniki Spalinowe

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2009

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R. 48, SC1

35--42

EN

Presented paper describes the most important modifications recently introduced to the high power engine piston-cylinder assembly and an analysis of effect of these changes on collaboration between rings and cylinder liner. One of the key issues brought about in the paper is the evaluation of constructional modifications performed on piston-cylinder assembly elements and their effect on oil film quality and friction losses encountered during operation of this assembly. Results of simulation tests on oil film formation on marine engine cylinder liner surface will be used for the analysis.

PL

W pracy opisano najważniejsze zmiany wprowadzone w ostatnich latach w budowie układu tłokowocylindrowego silników dużej mocy oraz przeanalizowano wpływ tych zmian na przebieg współpracy pierścieni z gładzią cylindra. Jednym z ważniejszych zagadnień poruszanych w pracy jest ocena wpływu zmian konstrukcyjnych elementów układu tłokowo-cylindrowego na jakości filmu olejowego tworzonego na gładzi cylindra oraz na straty tarcia towarzyszące pracy tego układu. Wnioski wynikające z dokonanego przeglądu zostaną wykorzystane przy budowie modeli matematycznych dotyczących kształtowania się parametrów filmu olejowego na gładzi cylindrowej silnika dużej mocy.

13

Problems of engine idle run at lowered temperature

Iskra A, Kałużny J, Babiak M, Krzymień P

Silniki Spalinowe

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2009

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R. 48, SC1

93--97

EN

The effect of engine temperature on fuel consumption has been analyzed in the paper. Actual conditions of passenger car engine run and increasing contribution of idle run time at the warm-up stage was the subject of particular interest. The paper presents results of engine fuel consumption vs. temperature when engine run idle; these tests have been carried out on the Volkswagen TDI engine on a test stand. Using a numerical model the effect of temperature on friction losses generated at engine main kinematic nodes were analyzed and possibilities of fuel consumption limitation at warm-up stage were defined as well.

PL

W artykule przeanalizowano wpływ temperatury silnika na zużycie paliwa. W sposób szczególny uwzględniono rzeczywiste warunki eksploatacji silników samochodów osobowych i rosnący udział czasu pracy na biegu jałowym w fazie nagrzewania silnika. Przedstawiono wyniki badań zużycia paliwa na biegu jałowym w funkcji temperatury silnika, badania te przeprowadzone zostały na silniku Volkswagen TDI. Przy użyciu modelu numerycznego przeanalizowano wpływ temperatury na straty tarcia w głównych węzłach tarcia silnika oraz określono możliwości ograniczenia zużycia paliwa w fazie nagrzewania silnika.

14

Collaboration of piston-cylinder assembly parts in conditions of transition

Krzymień P

Silniki Spalinowe

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2009

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R. 48, SC1

305--308

EN

The paper presents data on collaboration of complete piston and cylinder liner during engine warm-up. Change in piston-cylinder clearance as well as change in oil viscosity vs. temperature rise have been taken into consideration. The obtained results allow to conclude about the trend in lubrication oil consumption and friction losses generated by the piston-cylinder set before the engine achieves the state of heat balance.

PL

Artykuł opisuje współpracę tłoka z pierścieniami i tulei cylindrowej podczas rozgrzewania silnika. Uwzględniono zmiany luzu tłoka w cylindrze oraz zmianę lepkości oleju smarującego wywołane wzrostem temperatury. Uzyskane wyniki pozwalają przewidywać kierunek zmian tak zużycia oleju jak i strat tarcia jakie obserwowane są w silniku zanim osiągnie on stan równowagi cieplnej.

15

Model Tests Of Piston Ring-Cylinder Liner Collaboration On High Power Engines

Serdecki W., Krzymień P.

Journal of Polish CIMAC

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2009

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Vol. 4, no 2

259-266

EN

Proper selection of materials for cylinder liner and piston rings, correct design of collaborating surfaces as well as the use of lubricating oils of better and better properties assure long and reliable operation of piston rings in small and medium size engines. In the case of high power engines, especially marine ones failures caused by incorrect collaboration of rings and liner still happen. Supply and correct distribution of lubricating oil over cylinder surface could be one of the causes of this phenomenon. Regulations introduced by classification societies make impossible research on piston ring – cylinder liner set of running engines. Mathematical models or simulation test benches are the possible way of carrying out such tests. This paper presents some test rigs and analytical models revealing their advantages and shortcomings.

16

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

Serdecki W., Krzymień P.

Journal of KONES

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2009

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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.

17

Lubricating oil consumption at low temperatures

Iskra A., Krzymień A., Krzymień P.

Journal of KONES

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2009

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Vol. 16, No. 4

163-170

EN

The problem of lubricating oil consumption still seems to be important one at least because of the use of DPFs in exhaust systems of diesels. Even a minor consumption can be a source of particulate matter that blocksfilters. On the other hand formation of oil film parameters that guarantee minimum oil consumption could lead to the increased friction losses. Ali these remarks relate to the nominal temperature ofoperation. Situation can differ at temperature of cold start. Presented paper deals the problem of oil consumption at lower temperatures. The observation concerning friction losses under these conditions are mentioned as well. Parameters influencing the lubricating oil consumption, oil consumption at nominal temperature of engine run, oil consumption at low temperature are presented in the paper. As well course of oil film thickness, layer thickness and friction force for upper compression ring at engine nominal temperature of operation, course of oil film thickness, layer thickness and friction force for upper compression ring at lower engine run temperature, ring face wetting level at nominal temperature of operation, ring face wetting level at lower temperature of operation, lubricating oil consumption and friction losses generated by ring pack of single cylinder are subject of the paper.

18

Determination Of Cranktrain Frictional Resistance Using The Motored Engine Method

Serdecki W., Krzymień P.

Journal of Polish CIMAC

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2008

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Vol. 3, no 2

9-13

EN

Friction losses generated in engine kinematic nodes have an essential effect on its general efficiency. Measurement of these losses and indication of areas where they are generated can contribute to their minimization at the stage of engine design and during its operation as well. Most of the loss measurement methods requires an intervention in engine construction. The method of engine motoring does not require such intervention and at the same time offers possibility of precise measurement of engine resistance. The results obtained with the use of this method are considered hardly precise (among others because of different conditions during engine normal operation and its motoring), nevertheless they allow to estimate the influence of various effects on resistance observed on an engine. This study presents the results of tests on the effect of certain quantities characteristic for engine operation as well as properties of lube oil applied on the course of instantaneous values of motored engine torque. Another achievement of the study is the recommendation of test conditions securing highest possible accuracy of engine resistance torque determination. The simulation tests were carried out on the 170A.000 engine.

19

The effect of engine run irregularity level on oil film over cylinder liner surface

Iskra A., Krzymień P.

Journal of KONES

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2008

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Vol. 15, No. 2

125-129

EN

At idle run the engine operates in extremely unfavourable conditions because of vibrations generated by cyclic forces which makes that oil film parameters on liner surface become critical as well. This paper presents one of the crankshaft vibrations results namely the speed that differs from a generally known dependence described with two harmonics rco sin less than p and 1/2Xrco sin2 less than p. Taking into consideration the deterioration of oil film - the thickness in particular - at low idle speed, a further speed decrease could cause the oil film rupture. This means that in the case of piston-cylinder assembly elements the process of abrasive wear occurs first of all at idle run. Avoiding such situations lead to a considerable extension of engine life. The minimum piston speed outside both dead centres could be increased by the rise in idle run speed. Unfortunately, this leads to an increase in fuel consumption, e.g. when waiting for a green light in urban traffic. The only way to improve the oil film parameters at idle run is to improve the engine speed irregularity level 8. Certain possibilities in this field are offered by the hybrid drive. This paper presents an introductory analysis of possible improvement in oil film parameters over cylinder liner achieved by the decrease in speed irregularity level 8.

20

Hints for determination of the reasons of IC engine crank mechanism bearings damage

Krzymień A., Krzymień P.

Journal of KONES

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2008

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Vol. 15, No. 2

257-262

EN

In order to reduce the risk of premature wear or sudden failure of slide bearings it is necessary to take the relevant preventive steps. These can be determined on the ground of damage investigation and analysis of their causes. This paper presents some suggestions as to find causes of bearing failure, taking into account operational conditions, loads, applied lubricant and the quality of mating surfaces. A precise recognition of different causes of bearing failures should allow to reduce the hazard of premature wear and to take relevant preventing steps.Remarks on determination of bearing damage presented above and examples of damage presented in references try to show both to user and manufacturer their possible causes. If frequency of definite failure is occasional, most probably it results from unsuitable conditions of bearing operation (e.g. contaminated lubricating oil, oil film rupture, high temperature) or improper assembly (e.g. unsuitable bolt tightness, erroneous bearing clearance) of a certain engine. If damage concerns an entire engine family, one common cause should be defined. A precise recognition of damage various causes allow to diminish the hazard of premature wear by taking the appropriate preventing steps. Because of that very careful examination of the nature and distribution of any damage traces is recommended. Most often the research provide valuable hints how to construct, manufacture, assembly and operate bearings.