This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
An Investigation into the Onset of Knock in a CFR Engine
Technical Paper
2006-01-3344
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Internal combustion engine knock has limited compression ratios of spark ignition engines for most of the history of gasoline engines. This limitation continues to exist today. While knock is generally a low engine speed, high load phenomenon, this operating condition is infrequently used by many vehicle operators, and if the engine is brought to this operating condition generally little time is spent in this knock prone condition. This study seeks to investigate the transition into knock due to throttle changes from part to full load. The experimental results using a CFR engine operating on iso-octane fuel show that knock is delayed by at least one high load engine cycle after the throttle is opened. Optimization of spark timing to account for this effect provides for the best increase of engine load without audible knock occurring. Detailed analysis of the data with companion modeling strongly suggests that lower peak cylinder pressures from the cycle before the first Wide Open Throttle (WOT) cycle contribute to a cooler first WOT cycle charge temperature that hinders knock occurrence.
Recommended Content
Authors
Topic
Citation
Hamilton, L., Cowart, J., Minck, M., and Caton, P., "An Investigation into the Onset of Knock in a CFR Engine," SAE Technical Paper 2006-01-3344, 2006, https://doi.org/10.4271/2006-01-3344.Also In
References
- Konig, G. Sheppard, C.G.W. “End Gas Autoignition and Knock in a Spark Ignition Engine” SAE Paper 902135 1990
- Heywood, J. B. Chun, K. M. Cowart, J. S. “Understanding Knock in Engines” MIT Report 1989
- Russ, S. “A Review of the Effect of Engine Operating Conditions on Borderline Knock” Ford Research Laboratory 1996
- Cowart, J. S. et al. “The Intensity of Knock in an Internal Combustion Engine: An experimental and Modeling Study” SAE paper 922327 1992
- Noda, T. et al. “Development of Transient Knock Prediction Technique by Using a Zero-Dimensional Knocking Simulation with Chemical Kinetics” SAE paper 2004-01-0618 2004
- Heywood, J. B. “Internal Combustion Engine Fundamentals” McGraw-Hill 1988
- Burgdorf, K. Denbratt, I. “Comparison of Cylinder Pressure Based Knock Detection Methods” SAE paper 972932 1997
- Baik, S. H. Chun, K. M. “A Study on the Transient Knock Control in a Spark-Ignition Engine” SAE paper 981062 1998
- Aquino, C.F. “Transient A/F Characteristics for Cold Operation of the 5 L Central Fuel Injection Engine” SAE # 810494 1981
- Cowart, J. S. “A Comparison of Transient Air-Fuel Measurement Techniques” SAE Paper 2002-01-2753 2002
- Konig Maly Bradley Lau Sheppard “Role of Exothermic Centers on Knock Initiation and Knock Damage” SAE Paper 902136 1990
- Chun, K. M. Heywood, J. B. Keck, J. C. “Prediction of Knock Occurrence in a Spark-Ignition Engine,” Twenty-Second Symposium on Combustion, The Combustion Institute 1988
- Chen, Y. H. Chen, J. Y. “Development of Isooctane Skeletal Mechanisms for Fast and Accurate Predictions of SOC and Emissions of HCCI Engines based on LLNL Detailed Mechanism,” Western States Section of the Combustion Institute Meeting 2005