Wyniki wyszukiwania - BazTech

1

Reverse engineering of research engine cylinder-head

Cieślik Wojciech, Szwajca Filip, Wisłocki Krzysztof

Combustion Engines

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2022

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R. 61, nr 2

73--82

EN

The pursuit of increasing the efficiency of internal combustion engines is an ongoing engineering task that requires numerous research efforts. New concepts of injection or combustion systems require preliminary investigation work using research engines. These engines, usually single-cylinder, make it possible to isolate a single variable in a complex combustion mixture preparation process, thus enabling analysis of the changes being made. However, these engines are relatively expensive and their designs are offered by a limited number of manufacturers. The authors of this paper have successfully undertaken the engineering task of modifying an existing research engine cylinder head in such a way as to implement an electronically controlled variable valve timing system of the intake system. The process of reverse engineering, together with design assumptions that finally contributed to the construction of the assumed solution has been described in this paper.

2

Measurement and evaluation of functional and operational coefficients of hydraulic solenoid valve prototypes used for variable valve timing control in combustion engines

Kalinowski Marcin, Kamiński Zbigniew

Acta Mechanica et Automatica

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2021

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Vol. 15, no. 2

74--81

EN

: This paper describes the engineering structure and functions of a typical solenoid valve used in hydraulic mechanisms that are based on variable camshaft timing (VCT). The main operating parameters and functional utility coefficients of hydraulic solenoid valves have been defined. Tests of 10 reference and 10 prototype valves were run on a test stand for a comparative assessment of both engineering concepts based on Welch and Mann–Whitney statistical tests of the mean values of designated coefficients. The studies identified differences between both designs, and the obtained research material was used as an input to improve the performance of the engineered concept. To perform a final evaluation of the effects that arise as a result of changes introduced to some functional–operational coefficients, additional tests are required to be run on an engine testbed. The applied test methodology may then be used for control and verification tests of the valves, which can further be used in VCT technology.

3

Investigating the Effects of Variable Valve Timing on Spark Ignition Engine Performance

Bapiri Sepehr, Sorusbay Cem

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 2

100--111

EN

In this study, a prototype four-stroke spark ignition engine with four cylinders (two valves per cylinder), with and without turbocharger, as well as variable valve timing system to adjustment of variable valve duration has been investigated. This study covers the effects of intake valve opening (IVO), Intake valve closing (IVC), exhaust valve opening (EVO) and exhaust valve closing (EVC) angles on engine performances and fuel economy. The calculations of engine performance were carried out using the 1-Dimensional simulation with AVL BOOST software. The effects of different valve timing strategies and a combination of them from simulations were analyzed and compared with the reference fixed valve timing cases. It was shown that substantial improvements in fuel consumption and performance can be achieved. The improvements of Indicated Specific Fuel Consumption (ISFC) are remarkable in turbocharged models. Furthermore, we can see the noticeable improvements in torque and power in the naturally aspirated engine.

4

Thermodynamic analysis of combustion events in the natural gas fuelled SI engine with VVT

Szwaja M., Mazuro P., Szwaja S.

Journal of KONES

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2018

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Vol. 25, No. 4

421--427

EN

The main aim of the research was to investigate influence of overlap of the natural gas fuelled spark ignited engine on the following parameters: Indicated Mean Effective Pressure (IMEP), heat rate release including combustion phases (ignition lag, main combustion phase). The content of the study includes results from processing in-cylinder pressure measurements, heat release rate analysis, combustion phases, and finally the conclusions. The tests were carried out on the test bed including the single cylinder research engine with a displacement volume of 550 cm3. The engine was equipped with independent cam phasors for both intake and exhaust valves, but for this investigation, the exhaust valve timing was fixed (the exhaust cam centre line was fixed at -95 crank angle (CA) deg before Top Dead Centre) and intake valve timing was changed (the intake cam centre line was varied from 90 to 150 CA deg after Top Dead Centre). The overlap was changed in the range from 85 to 25 CA deg. 8 tests series were performed, each singular series consisted of 300 consecutive engine combustion cycles. As observed, by varying the valve overlap it contributes to significant change in the peak combustion pressure, peak of heat release rate, and combustion phases. Summing up, variable valve timing affects compression and expansion strokes by changing polytropic indexes due to various amounts of exhaust residuals trapped in the cylinder. It affects not only engine volumetric efficiency but also the heat release rate and IMEP, so it does engine performance. Thus, variable valve timing can be considered as valuable tool that can be applied to the natural gas fuelled internal combustion engine.

5

Control of fiat multiair valve-lift system using atmega microcontroller

Racewicz S., Olejnik A.

Journal of KONES

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2017

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Vol. 24, No. 3

229--236

EN

The article presents a device based on the ATmega microcontroller for precise Fiat MultiAir valve-lift system control. The Fiat MultiAir system is the patented electromechanical actuation system of the inlet valves. It allows a control of the inlet valves open time for each combustion chamber independently. The described device has been installed in the Fiat 0.9 TwinAir CNG 80 HP internal combustion engine controlled by the ECU Master open motor controller. As the ECU Master Controller software and hardware does not support Fiat’s MultiAir system control, the above-mentioned device had to be designed. The device consists of the ATmega88 microcontroller, which analyses the signals from the shaft and the cam sensors. Then, the DC converter is powering the solenoid valves of the MultiAir system via two transistors. When the solenoid valve is closed, the incompressible hydraulic fluid transmits the inletcam lobe’s motion to the valve as in a traditional engine. When the solenoid valve is open, the oil bypasses the passage, decoupling the valve, which then closes conventionally via spring pressure. In order to find the specific moments of turning the solenoids on and off the measurements on the original Fiat motor controller have been performed. The acquired oscillograms have been analysed and presented in the article. Studied Fiat 0.9 TwinAir engine is a part of the power generation unit and has been coupled with the three-phase electric power generator MeccAlte 16 kW with an AC exciter.

6

Variable valve timing scheduling in a 4-stroke internal combustion cylinder utilizing artificial neural networks

Bapiri S., Chaghaneh O., Ghomashi H.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 3

114--121

EN

The apparently simple structure of a four-stroke internal combustion cylinder belies the complicated problem of optimizing valve operation in response to a change in crankshaft rotation speed. The objective of this study was to determine the cylinder pressure for valve event angles in order to determine the optimal strategy for the timing of valve events when independently-actuated valves are available. In this work, an artificial neural network is applied to create a prediction matrix to anticipate the best variable valve timing approach according to rotation speed.

7

Experimental and modeling study of the gasoline HCCI engine with internal gas recirculation

Hunicz J., Gęca M.

Silniki Spalinowe

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2013

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R. 52, nr 1

3-9

EN

In this study experimental and modeling investigations of a gasoline HCCI engine with internal gas recirculation have been presented. Experimental measurements enabled identification of attainable range of valvetrain settings and air excess coefficient that allows a realization of the HCCI combustion. Factors determining the charge exchange process and the resulting in-cylinder temperature were specified based on computational analysis.

PL

W pracy przedstawiono wyniki badań eksperymentalnych i modelowych procesu roboczego benzynowego silnika HCCI z wewnętrzną recyrkulacją spalin. Na podstawie wyników badań eksperymentalnych określono zakres faz rozrządu oraz współczynnika nadmiaru powietrza, w którym możliwa jest realizacja procesu HCCI. Przeprowadzone badania symulacyjne pozwoliły na zidentyfikowanie czynników kształtujących przebieg wymiany ładunku oraz temperaturę w cylindrze.

8

Combustion control in gasoline HCCI engine with direct fuel injection and exhaust gas trapping

Hunicz J.

Journal of KONES

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2010

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Vol. 17, No. 2

137-144

EN

Homogeneous charge compression ignition (HCCI) seems to be the most promising solution for gasoline engines in the light of future emissions regulations. This novel combustion technique allows for significant reduction of fuel consumption and engine-out NOX emissions at low and medium engine load/speed conditions. High heat release rate enables realization of the Otto cycle close to ideal, increasing thermal efficiency. Among different approaches to invoke an auto-ignition of air-fuel mixture, exhaust gas trapping with the use of a negative valve overlap is under intensive investigations. The paper presents research results ofcontrolling an auto-ignition and combustion phasing in a single cylinder gasoline engine with direct fuel injection operated in the negative valve overlap mode. The experiments were performed at variable valvetrain settings, providing a control of EGR rate and volumetric efficiency. Additionally, the combustion process was investigated at variable air-fuel ratio. It was found that volumetric efficiency and EGR ratę are mainly dependent on exhaust valve timing, while a timing of intake valve determined combustion on-set and its duration. The effects of EGR rate and air-fuel ratio on combustion timing and exhaust gas emissions were isolated. The direct fuel injection showed its benefits versus mixture formation outside the cylinder. The application of variable injection timing provided additional possibility to control the combustion timing and exhaust emissions. However, it was found that the fuel injection strategy should be related to the engine load conditions.

9

Motion properties of hydraulically actuated valve train

Zbierski K., Smoczyński M.

Journal of KONES

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2009

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Vol. 16, No. 3

517-526

EN

This paper shows motion properties of hydraulically actuated engine valve train. The experimental model of the hydraulic valve drive is to be presented in this paper. It consists of parts: engine valve, hydraulic actuator and electric control hydraulic distributor, which control the flow of supply oil to the hydraulic actuator. It is hydraulic single-acting drive for valves of internal combustion engines. The methodology of the experimental research is to be explained. The measurements of the valve movement for the different supply pressures and for different opening distributor times were realized in this research. The recorded valve motion was base to detail analysis of velocity and acceleration of the engine valve motion. The researches show possibility of short opening time for typical valve of the high-speed internat combustion engine. Called attention to high speed and stroke against seat, while valve is closing. Especially called attention to possibility to formatting of the course of the valve lift. It may be used for better load exchange in internal combustion engines. The paper points out on the power supply of the system with the working pressure about 15 MPa what gives: smaller delay movement of the timing valve, quicker its opening, and also the large value of stroke of the timing valve.

PL

W artykule opisano właściwości ruchu zaworu rozrządu wymuszanego hydraulicznie. Zaprezentowano model doświadczalny składający się z zaworu rozrządu, siłownika hydraulicznego i rozdzielacza sterującego przepływem oleju zasilającego siłownik hydrauliczny. Jest to model hydraulicznego napędu zaworu jednostronnego działania. Uzasadniono przyjętą metodykę badań oraz przeprowadzono pomiary przebiegów wzniosu zaworu przy różnych wartościach ciśnień zasilających siłownik hydrauliczny i różnych czasach otwarcia rozdzielacza. W oparciu o zarejestrowane przebiegi wzniosów zaworu przeprowadzono szczegółową analizę prędkości i przyspieszeń zaworu. Pokazano możliwość uzyskania krótkiego czasu otwarcia dla typowego zaworu szybkoobrotowego silnika spalinowego. Zwrócono uwagę na dużą prędkość i uderzenie zaworu o gniazdo w chwili jego zamykania. Zwrócono także uwagę na stosunkowo dużą możliwość kształtowania krzywej wzniosu. Może zostać ona wykorzystana dla polepszenia wymiany ładunku w tłokowych silnikach spalinowych. Artykuł zwraca uwagę na zasilaniu układu ciśnieniem roboczym o wartości około 15 MPa, co daje: mniejsze opóźnienie ruchu zaworu rozrządu, szybsze jego otwieranie, a także dużą wartość skoku zaworu rozrządu.

10

Increase of the total efficiency using the Atkinson cycle in the spark ignition engine

Sendyka B., Sochan A.

Journal of KONES

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2009

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Vol. 16, No. 2

407-411

EN

The paper presents the results of investigations performed on a combustion engine with Atkinson cycle included and application of variable valve timing. Investigations were carried out at constant rotational speed 2500 and 3500 RPM and at throttle opening 25% and 50%. Influence of the advance/delay angle of inlet valves closing on formation of exhaust gases toxic components such as: carbon monoxide, hydrocarbons and nitric oxides was presented. Basing on the obtained results difference of toxicity of exhaust gases before and after application of phase shifter and their concentration in places of total efficiency increments was demonstrated. Especially The Atkinson cycle comparing with conventional Otto cycle, characteristics of the electric motor applied in Toyota Prius generation, starting and work of engines (combustion engine and electric motor) during vehicle standstill, relation of specific fuel consumption in function of rotational speed for a Toyota Prius engine, generation II, in total efficiency of engines with Atkinson cycle and Mitsubishi GDI in function of rotational speed, relative increase in total efficiency as rotational speed function, influence of intake valves opening angle on concentration in exhaust gases: carbon monoxide, hydrocarbons and nitric oxides at diferrent throttle opening values are presented in the paper.