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Reducing Part Load Pumping Loss and Improving Thermal Efficiency through High Compression Ratio Over-Expanded Cycle
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 08, 2013 by SAE International in United States
Annotation ability available
In vehicle application, most of time gasoline engines are part load operated, especially in city traffic, part load operation covers most common operation situations, however part load performances deteriorate due to pumping losses and low thermal efficiency. Many different technologies have been applied to improve part load performances. One of them is to adopt over-expanded (Atkinson/Miller) cycle, which uses late/early intake valve closing (LIVC/EIVC) to reduce pumping losses in part load operation. But over-expanded cycle has an intrinsic drawback in that combustion performance deteriorates due to the decline in the effective compression ratio (CR). Combining with high geometry CR may be an ideal solution, however there is a trade-off between maintaining a high CR for good part load fuel consumption and maintaining optimal combustion phasing at higher load. As a result, variable compression ratio systems, which include variable engine mechanisms and variable timing, need to be implemented to resolve these problems.
This paper analyzes potential benefits of meaningful concept of high CR over-expanded cycle gasoline engine combining over-expanded cycle with high geometry CR, while two stage variable valve lift (VVL) system is employed to achieve functional synergies. Compared with conventional over-expanded cycle engines, Atkinson cycle and Miller cycle work in concert to overcome their own drawbacks. LIVC (Atkinson cycle) with high valve lift is implemented at high load to reduce effective CR, which can optimize combustion phasing and reduce knock tendency. But thermal efficiency is still relatively high due to high geometry CR and un-affected expansion ratio. At part load, EIVC(Miller cycle) with low valve lift is adopted, effective CR is maintained at a high level to improve thermal efficiency, at the same time, pumping losses decrease as volumetric efficiency is reduced. The paper describes the fuel economy benefit obtained with this concept. In addition, power performance is also discussed.
CitationWan, Y. and Du, A., "Reducing Part Load Pumping Loss and Improving Thermal Efficiency through High Compression Ratio Over-Expanded Cycle," SAE Technical Paper 2013-01-1744, 2013, https://doi.org/10.4271/2013-01-1744.
- Martins , J. , Uzuneanu , K. , Ribeiro , B. , and Jasasky , O. Thermodynamic Analysis of an Over-Expanded Engine SAE Technical Paper 2004-01-0617 2004 10.4271/2004-01-0617
- Watanabe , S. , Koga , H. , and Kono , S. Research on Extended Expansion General-Purpose Engine Theoretical Analysis of Multiple Linkage System and Improvement of Thermal Efficiency SAE Technical Paper 2006-32-0101 2006 10.4271/2006-32-0101
- Mallikarjuna , J. and Ganesan , V. Theoretical and Experimental Investigations of Extended Expansion Concept for SI Engines SAE Technical Paper 2002-01-1740 2002 10.4271/2002-01-1740
- Boretti , A. and Scalzo , J. Exploring the Advantages of Atkinson Effects in Variable Compression Ratio Turbo GDI Engines SAE Technical Paper 2011-01-0367 2011 10.4271/2011-01-0367
- Gheorghiu , V. Ultra-Downsizing of Internal Combustion Engines SAE Technical Paper 2011-28-0049 2011 10.4271/2011-28-0049
- Parvate-Patil , G. , Hong , H. , and Gordon , B. An Assessment of Intake and Exhaust Philosophies for Variable Valve Timing SAE Technical Paper 2003-32-0078 2003 10.4271/2003-32-0078
- Leone , T. , Christenson , E. , and Stein , R. Comparison of Variable Camshaft Timing Strategies at Part Load SAE Technical Paper 960584 1996 10.4271/960584
- Zaccardi , J. , Pagot , A. , Vangraefschepe , F. , Dognin , C. et al. Optimal Design for a Highly Downsized Gasoline Engine SAE Technical Paper 2009-01-1794 2009 10.4271/2009-01-1794
- Muta , K. , Yamazaki , M. , and Tokieda , J. Development of New-Generation Hybrid System THS II - Drastic Improvement of Power Performance and Fuel Economy SAE Technical Paper 2004-01-0064 2004 10.4271/2004-01-0064
- Kawamoto , N. , Naiki , K. , Kawai , T. , Shikida , T. et al. Development of New 1.8-Liter Engine for Hybrid Vehicles SAE Technical Paper 2009-01-1061 2009 10.4271/2009-01-1061
- Hitomi , M. , Sasaki , J. , Hatamura , K. , and Yano , Y. Mechanism of Improving Fuel Efficiency by Miller Cycle and Its Future Prospect SAE Technical Paper 950974 1995 10.4271/950974
- França , O. Impact Of The Miller Cycle in the Efficiency of an FVVT (Fully Variable Valve Train) Engine during Part Load Operation SAE Technical Paper 2009-36-0081 2009 10.4271/2009-36-0081
- Akihisa , D. and Daisaku , S. Research on Improving Thermal Efficiency through Variable Super-High Expansion Ratio Cycle SAE Technical Paper 2010-01-0174 2010 10.4271/2010-01-0174
- Taylor , J. , Fraser , N. , Dingelstadt , R. , and Hoffmann , H. Benefits of Late Inlet Valve Timing Strategies Afforded Through the Use of Intake Cam In Cam Applied to a Gasoline Turbocharged Downsized Engine SAE Technical Paper 2011-01-0360 2011 10.4271/2011-01-0360
- Kadota , M. , Ishikawa , S. , Yamamoto , K. , Kato , M. et al. Advanced Control System of Variable Compression Ratio (VCR) Engine with Dual Piston Mechanism SAE Int. J. Engines 2 1 1009 1018 2009 10.4271/2009-01-1063
- Sugiyama , T. , Hiyoshi , R. , Takemura , S. , and Aoyama , S. Technology for Improving Engine Performance using Variable Mechanisms SAE Technical Paper 2007-01-1290 2007 10.4271/2007-01-1290
- Cao , Y. Thermodynamic Cycles of Internal Combustion Engines for Increased Thermal Efficiency, Constant-Volume Combustion, Variable Compression Ratio, and Cold Start SAE Technical Paper 2007-01-4115 2007 10.4271/2007-01-4115
- Stansfield , P. , Wigley , G. , Garner , C. , Patel , R. et al. Unthrottled Engine Operation using Variable Valve Actuation: The Impact on the Flow Field, Mixing and Combustion SAE Technical Paper 2007-01-1414 2007 10.4271/2007-01-1414
- Aimin DU , Guoqiang LI , Jiejie WU Simulation of working process for 4G 1 8 gasoline engine and the test verification Machinery Design & Manufacture 2011
- Deyu Wu , Maolin Fu , Jianquan Li , Xiaoying Gu A Study on Knock Intensity Indices in Spark Ignition Engines Transactions of CSICE 1997
- Shun-ai JIN , Yong LI , Xiu-jing SHANG Simulation of Combustion Process and Knock Prediction in Gasoline Engines Transactions of CSICE 1999
- Hattrell , T. , Sheppard , C. , Burluka , A. , Neumeister , J. et al. Burn Rate Implications of Alternative Knock Reduction Strategies for Turbocharged SI Engines SAE Technical Paper 2006-01-1110 2006 10.4271/2006-01-1110
- Gheorghiu , V. CO2-Emission Reduction by Means of Enhancing the Thermal Conversion Efficiency of Ice Cycles SAE Technical Paper 2010-01-1511 2010 10.4271/2010-01-1511
- Gheorghiu , V. CO 2 -Emission Reduction by Means of Enhanced Thermal Conversion Efficiency of Ice Cycles SAE Technical Paper 2009-24-0081 2009 10.4271/2009-24-0081