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1

Study on selected parameters of engine with the active combustion chamber

Głogowski Michał, Woźniak Marek, Szydłowski Tomasz, Siczek Krzysztof

Combustion Engines

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2023

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R. 62, nr 3

3--12

EN

The present study was focused on the combustion engine with a variable compression ratio (VCR), namely the four-stroke air-cooled engine with the active combustion chamber (ACC). An indicated pressure, torque, power, and specific fuel consumption of that engine were investigated experimentally as a goal of the present study. Experiments were conducted using two versions of an engine. Two parameters particularly influencing the ACC engine performance including the maximum compression ratio CRmax and the indicator γfm determining the correct operation of the ACC system, were described. It was found that the ACC engine allowed avoiding detonation combustion without changing the amount and composition of the combustible mixture, and even without delaying the ignition advance angle. In addition, the possible range of control of the combustion process allowed the ACC engine to operate with different types of hydrocarbon fuels, for example, in the form of petrol with various alcohol admixtures. The very intense flow of the combustible mixture inside the cylinder of the ACC engine allowed describing the combustion in the ACC engine with zero-dimensional mathematical models with the dual Vibe function providing the proper characterization of the heat release process. The use of very high maximum compression ratios allows the ACC engine to operate to a certain extent as a Homogeneous Charge Compression Ignition (HCCI) engine with high lambda coefficients.

2

Theoretical study of the motion characteristics of a variable length connecting rod mechanism

Chen Jiadui, Liu Qinghua, Yang B.

Engineering Transactions

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2022

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Vol. 70, iss. 1

3--22

EN

The sustainable development of society calls for automobile engines with high efficiency and very low pollutant emission. The variable compression ratio (VCR) technique is one of the effective methods to deal with this issue. Engines with variable length connecting rod (VLEs) yield higher efficiency than other VCR engines. This paper focuses on a variable length connecting rod mechanism that achieves a VCR by changing the positions of the bottom dead center (BDC) and the top dead center (TDC) (controlled by the rotation of the eccentric sleeve) relative to the crankshaft. A kinematic model is also proposed to calculate and analyze the motion characteristics of the variable length connecting rod mechanism. The effects of eccentric size and eccentric phase on the piston motion, the TDC and BDC positions, the stroke length, the crank angles at TDC and BDC, and the compression ratio are studied in detail. It is found that the piston exhibits good motion characteristics with proper eccentric size and eccentric phase, and the compression ratio can be adjusted by varying the eccentric phase with proper eccentric size. A comparison between the proposed mechanism with another mechanism is also conducted. Therefore, this work can serve as a necessary reference for designing, analyzing, and optimizing VLEs.

3

The Szymkowiak’s over-expanded cycle in the rocker engine with the variable compression ratio - kinematics

Szwaja Stanisław, Szymkowiak Mirosław

Combustion Engines

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2022

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R. 61, nr 2

68--72

EN

The article discusses the innovative concept of the over-expanded thermodynamic cycle, the author of which is the Polish engineer-designer Mirosław Szymkowiak. This cycle is realized on the basis of a new and innovative, previously unknown design, of a piston-crankshaft linkage mechanism with the aid of an additional element known as a rocker arm. Additionally, the proposed mechanism allows for a smooth change of the compression/expansion ratio of the engine during its operation. In the beginning, the earlier conceptions of the rocker engine developed by Szymkowiak were presented, and then the main construction assumptions and kinematic calculations were described. It was confirmed, that the developed linkage has big potential in improving the engine's thermal efficiency by approximately 12% relative. Additionally, it significantly reduces the exhaust gas pressure, when the exhaust valve is opened, therefore, contributes to the reduction of the noise emitted by the engine.

4

High compression spark ignition engine with variable compression ratio using Active Combustion Chamber

Kubiak Przemysław, Glogowski Michal, Soghabatyan Tigran, Mrowicki Adam, D'Errico Gianluca

Archiwum Motoryzacji

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2019

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Vol. 86, nr 4

5--26

EN

Abstract In this article Authors present the continuation of the calculations for theoretical ACC engine cycle, considering additionally “VCR function” – changeable compression level. For this purpose the self-acting volume change, realized by ACC system, was used. The ACC system was adjusted appropriately to control the compression level. The analysis is based on three cases, representing delayed, premature and optimal reaction of ACC system. Reactions are presented in form of plots with indicated pressure in the combustion chamber. As the result of the conducted analysis and interpretation of obtained graphs, the calculation approach of compression ratio for ACC presented in previous article is being challenged. For the optimal reaction of ACC system, the theoretical operation schematics are devised and presented in the key points of the work. Based on the schematics, the values of theoretical efficiency were calculated for different cycles of theoretical ACC engine, in which regulation of compression ratio takes place. Moreover, the presented analysis includes graphs with optimal courses of indicated pressure for significantly different work parameters of ACC engine, showing its regulation possibilities. Also the time scaled graphs (with millisecond as basic time unit) are presented to show the possibilities of dynamic ACC systems, which are comparable with the combustion time (from 3 to 0,5 ms). In this paper the general discussion is started about the compression ratio in more complex kinematic systems including ACC.

5

Device for control the valvetrain and cylinder pressure of a spark-ignition engine

Mamala J., Graba M., Bieniek A., Hennek K.

Journal of KONES

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2018

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Vol. 25, No. 3

339--346

EN

This article describes the method of controlling an electric magnetic linear actuator that moves an inlet valve of an internal combustion engine. Thanks to the use of the electric control of the inlet valve of the internal combustion engine, it was possible to implement a variable effective compression ratio of the operating power unit, adapting it to the current needs and engine load. In this design, valvetrain was modified by introducing an autonomous intake valve operation with the use of a specially designed electromagnetic actuator. The introduction of this system necessitated an additional modification of the intake camshaft. The control was carried out with the use of a real-time controller with a built-in FPGA unit. The proposed design of a system with an electromagnetic actuator will allow obtaining an additional degree of freedom in the control unit. Particular attention should be paid to registered values or air pressure in the intake stroke for a closed or partially opened throttle, which generates significant pumping losses. The use of an electromagnetic actuator in the intake can help reduce said losses.

6

Nissan gasoline engine strategy for higher thermal efficiency

Mizuno H.

Combustion Engines

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2017

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R. 56, nr 2

141--145

EN

Rising highly concern about the environment has led to demands for the improvement of the efficiency of gasoline engines. Engine thermal efficiency will reach about 40% by technologies as boosted EGR, miller cycle and so on. This evolution trend will be continuously required to survive engines for the future. In this background, further improvement based on theoretical thermal efficiency of high compression ratio and specific heat capacity should be promoted. In addition, energy loss reduction such as represented by cooling loss and friction is also very important for the efficient and effective improvement. NISSAN’s challenges will be introduced to solve these propositions.

7

Research on a prototype spark ignition (SI) variable compression ratio engine fitted with a pneumatic energy accumulator

Łaziński P., Głogowski M., Leyko J.

Combustion Engines

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2014

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R. 53, nr 4

54--65

EN

The paper describes investigations performed on a prototype variable compression ratio engine fitted with a pneumatic energy accumulator. The engine was built in the Chair of Vehicles and Basics of Machine Design at Lodz University of Technology. Due to the design and principle of operation, the engine may be an alternative to the already existing VCR engines. The pneumatic energy accumulator fitted in the cylinder head with an additional moving piston allows continuous adjustment of the compression ratio. The system is adaptive and adjusts itself to the engine load, reducing the increment of maximum pressure inside the cylinder. The research focuses on the influence of adjustment parameters of the energy accumulator on the movement of the additional piston and engine performance. Engine operation stability and reproducibility of the cycles has also been investigated. An attempt was made to characterize the engine and the energy accumulator in terms of efficiency and range of applicability (profitability of application).

PL

W artykule opisano badania prototypowego silnika o zmiennym stopniu sprężania wyposażonego w pneumatyczny akumulator energii. Silnik zbudowano w Katedrze Pojazdów i Podstaw Budowy Maszyn Politechniki Łódzkiej. Ze względu na swą konstrukcję i zasadę działania jest to pewna alternatywa dla dzisiejszych rozwiniętych już konstrukcji silników VCR. Zamontowany w głowicy pneumatyczny akumulator energii z ruchomym dodatkowym tłokiem pozwala na ciągłą regulację stopnia sprężania. Regulacja ta jest również adaptacyjna i dostosowuje stopień sprężania do obciążenia silnika, ograniczając wzrost ciśnienia maksymalnego w cylindrze. W badaniach skupiono się nad wpływem parametrów regulacyjnych akumulatora energii na ruch dodatkowego tłoka oraz osiągi silnika. Badano także stabilność pracy i powtarzalność cykli. Podjęto próbę scharakteryzowania silnika i pneumatycznego akumulatora energii pod względem sprawności i wyznaczenia przedziału stosowalności (opłacalności efektów stosowania).

8

Modification of the SI engine parameters with adaptation control of compression ratio

Sendyka B., Soczówka J.

Silniki Spalinowe

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2009

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R. 48, SC2

326--330

EN

The first part of the publication comprises the idea of controlling compression ratio in the SI engine. It is also shown the impact of flexible stage of compression on the parameters of the engine and improving them. The publication also reveals the system of adaptive control and benefits gained from it. Moreover, the factors influencing the controlling system, forces operating on controlling system by variable compression ratio are also presented. The second part of the publication presents the results of experimental researches on engines with adaptation controlling of flexible compression ratio. There are also shown charts of the engine performance to the limits of ranges for controlling taking into consideration the lowest and highest range of compression in the function of rotational speed. The last part includes conclusions concerning benefits from applying the flexible compression ratio and adaptation controlling system. It also mentions possibilities of adapting the system to stock production.

PL

W pierwszej części publikacji zawarta jest idea sterowania stopniem sprężania w silniku ZI. Przedstawiono wpływ zmiennego stopnia sprężania na parametry silnika i polepszenie tych parametrów. Pokazany jest układ adaptacyjnego sterowania oraz korzyści uzyskane z jego zastosowania. Przedstawiono także czynniki wpływające na układ sterowania, siły działające na układ sterowania zmiennym stopniem sprężania. Opisano główne elementy składowe układu sterowania oraz wielkości sterujące układem. W drugiej części publikacji przedstawiono wyniki badań eksperymentalnego silnika z adaptacyjnym sterowaniem zmiennego stopnia sprężania. Przestawiono wykresy sprawności ogólnej silnika w granicznych zakresach sterowania dla najmniejszego i największego stopnia sprężania w funkcji prędkości obrotowej dla jednakowych obciążeń. W końcowej części zawarto wnioski na temat korzyści płynących z zastosowania zmiennego stopnia sprężania oraz adaptacyjnego układu sterowania. Opisano możliwość przystosowania takiego układu do produkcji seryjnej.

9

A preliminary project of multi cylinder, variable compression ratio (VCR) engine for research purposes

Lejda K., Woś P.

Silniki Spalinowe

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2009

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R. 48, SC2

152--157

EN

In the paper the conception for application of variable compression ratio technology in fourcylinder, research engine is presented. Variation of the engine compression ratio is performed by changing combustion chambers volume owing to shifting the cylinder block - head assembly perpendicularly to the crankshaft axis. The pros and cons of that method in comparison with few other, still studied projects are described. The paper also consists of an analysis of possible range for CR variation, as well calculations for selection appropriate working elements in the shifting system. The range of the next development works, which are essential for project finalization, is specified. The construction based at 4 VD 14,5/12-1 SRW engine, will be used for studying fuel economy and CO2 reduction problems in relation to the newest natural environment requirements. The research on an advanced, near-zero emission, low temperature combustion (LTC) technology will be also possible.

PL

W artykule przedstawiona jest koncepcja realizacji technologii zmiennego stopnia sprężania w badawczym silniku czterocylindrowym, polegająca na zmianie objętości komór spalania wskutek kontrolowanego przesuwu i pozycjonowania zespołu blok cylindrowy – głowica względem wału korbowego silnika. Opisane są zalety i wady przedstawionej metody w porównaniu do innych, będących wciąż w fazie studialnej projektów. Artykuł zawiera analizę możliwego do osiągnięcia zakresu zmienności stopnia sprężania oraz obliczenia i dobór elementów wykonawczych w układzie przesuwu zespołu cylinder - głowica. Określono również zakres dalszych prac konstrukcyjnych niezbędnych dla finalizacji projektu. Opracowywany silnik, oparty o istniejącą konstrukcję 4 VD 14,5/12-1 SRW, będzie wykorzystany do badań nad możliwością obniżenia zużycia paliwa i redukcji emisji CO2 w świetle najnowszych wymagań w tym zakresie. Możliwe będą też badania procesów roboczych silnika wykorzystujących zaawansowane, niskoemisyjne techniki spalania niskotemperaturowego.