Variable Compression Ratio - A Design Solution for Fuel Economy Concepts

Schwaderlapp, Markus; Habermann, Knut; Yapici, Kurt Imren

doi:10.4271/2002-01-1103

Cited by 44 publications

(10 citation statements)

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“…Kwak et al [14] proposed a kinematic conceptual design procedure for in-line fourcylinder VCR engine mechanisms considering vertical second harmonic acceleration. The compression ratio of the VCR engine can be modified by moving or tilting the cylinder head, moving the crankshaft axis, varying the piston deck height or the combustion chamber volume, moving the crankpin, or modifying the connecting rod geometry using a control linkage system [1,15,16]. Mo et al [17] classified various VCR engine mechanisms according to their kinematic graphs.…”

Section: Kinematic Chains Mechanisms and Graphsmentioning

confidence: 99%

“…However, most vehicles sold on the market are still powered by internal combustion (IC) engines, and in order to keep pace with this global trend, technologies for ecofriendly and high-efficiency IC engines are constantly being developed, with variable compression ratio (VCR) engines being a classic example. The VCR engine operates at high or low compression ratios to maximize the efficiency or to avoid knock depending on the operating conditions, and numerous studies have proved that the technology can improve fuel efficiency and performance [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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Type Synthesis of Variable Compression Ratio Engine Mechanisms

Shim

Kwak

et al. 2020

Applied Sciences

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Type synthesis of two-degrees-of-freedom (DOF) planar mechanisms has been carried out using graph theory to determine the possible kinematic structures of variable compression ratio (VCR) engine mechanisms with two to three independent loops, and has resulted in the structures of 87 mechanisms satisfying search specification. By applying evaluation criteria to the enumerated mechanisms, the kinematic structures of three mechanisms are selected as suitable VCR engine mechanisms and verified by analysis results. In this research, VCR engine mechanisms with revolute joints and only one prismatic joint are enumerated, and the basic method to determine the VCR engine mechanisms with higher pairs is discussed. The procedure used in this research can be utilized to determine the kinematic structures of desired mechanisms and the results can be used as an atlas of two-DOF adjustable slider-crank mechanisms.

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Section: Kinematic Chains Mechanisms and Graphsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Type Synthesis of Variable Compression Ratio Engine Mechanisms

Shim

Kwak

et al. 2020

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…One of them was to use a connecting rod with variable length [27]. While the other one used eccentric bearings that change the TDC and BDC positions of the piston [28].…”

Section: Variable Compression Ratiomentioning

confidence: 99%

Zero-dimensional modelling of a four-cylinder turbocharged diesel engine with variable compression ratio and its effects on emissions

Khan

Gül

2019

SN Appl. Sci.

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With emission legislation becoming ever more stringent, declining fossil resources and an increase in greenhouse effect caused by CO 2 emissions, manufacturers are exploring new ways to match the emissions regulations without compromising on the performance of the engine. This study included development of zero-dimensional model of a 2.0 L turbocharged diesel engine and then study the effects of changing its compression ratio in the numerical model. This paper gave a framework in determining the effect of compression ratios in different operational conditions of the engine. Implementation of variable compression ratio technology on a numerical model proved to be very cost-effective, time saving and validated the fact that numerical models can be used to study different parameters of the engines during the development stage. The main effect of an increase in compression ratio, was found to be as expected, a decrease in brake specific fuel consumption and an increase in thermal efficiency with a greater impact at low rpm-low load regions. Assuming, that the variable compression ratio technology can be utilized in the engine, this work found the best combination of compression ratios around the engine map, giving a best fit of trade-offs between the emissions and performance of the engine. This study also validates the fact that variable compression ratio technology, if implemented in the engine could not only reduce emissions of the engine but can be given as an option to the end-user to switch to more economic fuel consumption values during idling or cruising at long distant journeys.

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“…Variable compression ratio technology has long been recognized as a method to improve engine fuel economy [1,2,3,4,5,6,7]. At low power levels the engine operates at higher compression ratio to capture the benefits of higher thermal efficiency, while at high power levels the engine operates at lower compression ratio to prevent knock.…”

Section: Introductionmentioning

confidence: 99%

Geometric Parameter Design of a Multiple-Link Mechanism for Advantageous Compression Ratio and Displacement Characteristics

Jiang

Smith

2014

SAE Technical Paper Series

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Variable compression ratio and variable displacement technologies are adopted in internal combustion engines because these features provide further degrees of freedom to optimize engine performance for various operating conditions. This paper focuses on a multiple-link mechanism that realizes variable compression ratio and displacement by varying the piston motion, specifically the Top Dead Center (TDC) and Bottom Dead Center (BDC) positions relative to the crankshaft. It is determined that a major requirement for the design of this mechanism is when the control action changes monotonically over its whole range, the compression ratio and the displacement should change in opposite directions monotonically. This paper presents an approach on how to achieve multiple-link mechanism geometric designs that fulfill this requirement. First, a necessary and sufficient condition, and a stronger sufficient condition are obtained on how the TDC and BDC positions should change with respect to the control action to fulfill the design requirement. Then Design of Experiments (DoE) methodology is used for creating sets of geometric designs of the mechanism, for which kinematics are calculated and checked against the conditions. A feasible design that satisfies the conditions is selected and detailed study on such characteristics as piston motion, stroke length, displacement, combustion chamber volume, and compression ratio etc. is performed. The design approach and obtained results serve as a basis for further analysis and optimization of the multiple-link mechanism.

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Variable Compression Ratio - A Design Solution for Fuel Economy Concepts

Cited by 44 publications

References 0 publications

Type Synthesis of Variable Compression Ratio Engine Mechanisms

Type Synthesis of Variable Compression Ratio Engine Mechanisms

Zero-dimensional modelling of a four-cylinder turbocharged diesel engine with variable compression ratio and its effects on emissions

Geometric Parameter Design of a Multiple-Link Mechanism for Advantageous Compression Ratio and Displacement Characteristics

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