Wyniki wyszukiwania - Biblioteka Nauki

1

Mathematical model of the hydraulic valve timing system

100%

Mitianiec W. , Bac J.

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tom Vol. 18, No. 2

311-321

EN

The paper presents a conception and mathematical model of the hydraulic valve timing system. It describes the complex physical phenomena that occur between system components and the hydraulic liquid. Basing on postulates and initial conditions model, one was simulated the movement of elements system resulting from the flow of pressured liquid. The model was simulated in Matlab/Simulink program for different geometrical parameters of the hydraulic system and electric control parameters in order to obtain required lift and timing of valves in YARIS SI 1.3 l engine. The paper presents structure of Simulink model and results of calculation in Simulink. One represented the influence of various parameters and dimensions system on the character of valve lift. The relationship between the diameter of the rod and the liquid significantly affects the valve time-area parameter. The feeding liquid pressure in the system and the re-steering time have the biggest influence on course of valve lift. After preliminary tests the guidelines for the hydraulic valve timing system have been developed. The determined simulation results in Simulink were used to calculate of the device work in the engine computer model created in GT-Power program. The proposed solution was compared with the cam valve timing systems. On the basis of the simulations tests show a big superiority of the hydraulic valve timing system at higher rotational speeds.

2

Tribological properties of the seat insert - valve - guide assembly for valve driven magnetoelectrically

88%

Siczek K. , Siczek K.

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tom Vol. 17, No. 4

439-445

EN

The researches have been carried out, where the object has been the set of two friction couples: valve stem - valve guide and valve seat - seat insert. The camless driven valve has been common for each of such cases. The analyzed valve has been driven by magnetoelectrical drive. The speciał research stand has been elaborated and its scheme has been presented in the article. It has been measured the valve lift and valve acceleration, the impact force, the friction force, temperature values for valve guide and for seat insert, sound level during impacting on the stand. The aim of researches has been to determine the dynamic parameters, the friction force between valve stem and valve guide, the impact force for valve impacting seat insert vs. frequency and valve lift. The analyzed valves have mated with seat inserts and valve guides made of cast iron, in oil absence. The valves have been made of TiAl6Zr4Sn2Mo2 alloy. The researched friction couples have operated in temperature equal 293 K. The increase of frequency has resulted in small changes for values of lift and in greater changes of acceleration, during valve impact into its seat insert. The greatest values of impact force and acceleration have been for the small, middle and high values of valve lift, either. The ratio of impact force and valve acceleration has changed in thin bands. The friction force has decreased slightly with frequency increase and has decreased with valve lift increase. The sound level has increased with the frequency increase, and has not been dependent upon valve lift.

3

The simulation researches on the wear for elements of the seat insert-valve-valve guide assembly

88%

Siczek K. , Kuchar M.

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tom Vol. 17, No. 4

431-438

EN

The researches have been carried out, where the object has been the elements of valve trains in the different combustion engines. Those elements have been valve, valve guide and seat insert. The analysed valves have been driven by special camshaft, with the cams of trapezoid shape. The special research stand has been elaborated and its scheme has been presented in the article. The mentioned research stand has been driven by electric motor. The rotational velocity of the camshaft has been controlled and measured. The aim of the researches has been to obtain values of wear for valve, seat insert, valve guide vs. valve lift, and rpm of camshaft. The dynamic parameters have been analyzed for the seat insert - valve - valve guide assembly, experimentally and by simulation either. During researches the values of valve lift, of valve acceleration, of temperature for seat insert and additionally sound level have been measured. The wear of valve, seat insert and valve guide has been measured, basing on their initial and post-research geometry. The results of experimental researches obtained for different materials for valve, valve guide and seat insert have been presented in the article. The simulation model of the analyzed seat insert - valve - valve guide assembly has been elaborated and presented in the article. Such model has been needed to calculate the values o f the settle velocityfor the analyzed valve. The wear of titanium valve has been a little greater than of the steel valve, the wear of cast iron seat insert mating with steel valve has been much greater than for titanium valve case. The wear of valve guides, made of bronze has been several times less than those of cast iron.

4

The researches on the tribological properties of elements of the seat insert-valve-valve guide assembly

88%

Siczek K.

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tom Vol. 17, No. 4

423-430

EN

The researches have been carried out, where the object has been the elements of valve trains in the different combustion engines. Those elements have been valve, valve guide and seat insert. The analysed valves have been driven by special camshaft, with the cams of trapezoid shape. The special research stand has been elaborated and its scheme has been presented in the article. The mentioned research stand has been driven by electric motor. The rotational velocity of the camshaft has been controlled and measured. The aim of the researches has been to obtain values of wear for valve, seat insert, valve guide vs. valve lift, and rpm of camshaft. The dynamic parameters have been analyzed for the seat insert - valve - valve guide assembly, experimentally and by simulation either. During researches the values of valve lift, of valve acceleration, of temperature for seat insert and additionally sound level have been measured. The wear of valve, seat insert and valve guide has been measured, basing on their initial and post-research geometry. The results of experimental researches obtained for different materials for valve, valve guide and seat insert have been presented in the article. The simulation model of the analyzed seat insert - valve - valve guide assembly has been elaborated and presented in the article. Such model has been needed to calculate the values o f the settle velocityfor the analyzed valve. The wear of titanium valve has been a little greater than of the steel valve, the wear of cast iron seat insert mating with steel valve has been much greater than for titanium valve case. The wear of valve guides, made of bronze has been several times less than those of cast iron.

5

Pulse powered turbine engine concept – numerical analysis of influence of different valve timing concepts on thermodynamic performance

75%

Tarnawski P. , Ostapski W.

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nr 3

6

Tendencje rozwojowe okrętowych silników spalinowych

51%

Kowalski J.

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2016

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tom nr 12

19--24

PL

W ostatnim 10-leciu nastąpił gwałtowny rozwój konstrukcji tłokowych silników spalinowych. Był on spowodowany m.in. zaostrzeniem przepisów dotyczących ochrony środowiska, w tym emisji związków toksycznych do atmosfery. W pracy zaprezentowano nowe rozwiązania techniczne stosowane w silnikach okrętowych, prowadzące do ograniczenia emisji tlenków azotu i tlenków siarki przy jednoczesnym ograniczeniu zużycia paliwa. Prezentowana analiza ma na celu przedstawienie i ocenę dostępnych rozwiązań konstrukcyjnych oraz próbę oceny dalszych kierunków rozwoju silników stosowanych w okrętownictwie. Skupiono się przy tym na tych rozwiązaniach konstrukcyjnych, które wpływają na przebieg procesu spalania w cylindrach silnika. Przedstawione zostały również koncepcje, które jak dotychczas nie znalazły szerszego zastosowania w okrętownictwie, ale mogą stanowić obiecującą alternatywę w przyszłych rozwiązaniach konstrukcyjnych silników spalinowych.

EN

Rapid development of the construction of internal combustion engines occurs in the past 10 years. It was caused by, i.e. the growth of environmental legislation, including toxic emissions into the atmosphere. The paper presents new technical solutions, used in marine engines, leading to the reduction of emissions of nitrogen oxides and sulfur oxides while reducing fuel consumption. Mentioned analysis is to present and evaluate the available design solutions and attempt to assess further development directions of marine engines constructions. The special attention was paid on construction solutions which influence on the combustion process in the engine cylinders. Paper includes concepts that so far have not found wider application in shipbuilding also, but it may be a promising alternative for future construction solutions for combustion engines.