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Modelling and Control of Engine Torque for Short-Circuit Flow and EGR Evacuation
ISSN: 0148-7191, e-ISSN: 2688-3627
Published March 28, 2017 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Low-Pressure Exhaust Gas Recirculation (LP-EGR) has been shown to be an effective means of improving fuel economy and suppressing knock in downsized, boosted, spark ignition engines. LP-EGR is particularly beneficial at low-speed, high-load conditions, but can lead to combustion instability at lower loads. The transport delays inherent in LP-EGR systems slow the reduction of intake manifold EGR concentrations during tip-out events, which may lead to excessive EGR concentrations at low load.
This paper explores leveraging Variable Valve Timing (VVT) as a means of improving the rate of reduction of intake manifold EGR concentration prior to tip-out. At higher boost levels, high valve overlap may result in intake manifold gas passing directly to the exhaust manifold. This short-circuiting behaviour could potentially improve EGR evacuation rates. However, introducing short-circuit flow may lead to lean exhaust flow through the catalyst, and/or necessitate rich in-cylinder conditions that could counteract the fuel economy benefits of increasing high load LP-EGR rates. Therefore, this paper seeks to quantify the improvement in EGR evacuation rate and duration of short circuiting that may be achieved while at boosted conditions with high valve overlap, in preparation for a tip out.
To conduct this investigation, a controller is first proposed, capable of regulating torque at boosted operating conditions with high valve overlap and external EGR. This controller extends a published control architecture, by accounting for both short-circuit flow and external EGR.
The developed controller is then applied to a GT-Power model to regulate torque during constant torque LP-EGR evacuations, where high valve overlap is shown to improve evacuation times by 15-25%.
CitationWiese, A., Stefanopoulou, A., Buckland, J., and Karnik, A., "Modelling and Control of Engine Torque for Short-Circuit Flow and EGR Evacuation," SAE Technical Paper 2017-01-0606, 2017, https://doi.org/10.4271/2017-01-0606.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
- Takaki, D., Tsuchida, H., Kobara, T., Akagi, M. et al., "Study of an EGR System for Downsizing Turbocharged Gasoline Engine to Improve Fuel Economy," SAE Technical Paper 2014-01-1199, 2014, doi:10.4271/2014-01-1199.
- Cairns, A., Fraser, N., and Blaxill, H., "Pre Versus Post Compressor Supply of Cooled EGR for Full Load Fuel Economy in Turbocharged Gasoline Engines," SAE Technical Paper 2008-01-0425, 2008, doi:10.4271/2008-01-0425.
- Wei, H., Zhu, T., Shu, G., Tan, L., et al., “Gasoline Engine Exhaust Gas Recirculation - A Review”. Applied Energy. 99:534-544, 2012.
- Roth, D., Keller, P., and Becker, M., "Requirements of External EGR Systems for Dual Cam Phaser Turbo GDI Engines," SAE Technical Paper 2010-01-0588, 2010, doi:10.4271/2010-01-0588.
- Karnik, A. Y., Jankovic, M. J., and Shelby, M. H., “Scavenging in a Turbocharged Engine”. Int. J. Powertrains, 1(4):420-437, 2012.
- Colin, G., Chamaillard, Y., and Bellicaud, B., 2011. “Robust Control for the Air Path of a Downsized Engine”. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 225, 2011.
- GT-Suite (v7.4.0 Build 1). Windows, Gamma Technologies.
- Buckland, J. H., Jankovic, M., Grizzle, J. W., and Freudenberg, J. S., “Estimation of Exhaust Manifold Pressure in Turbocharged Gasoline Engines with Variable Valve Timing”. In ASME 2008 Dynamic Systems and Control Conference, pp. 315-321. American Society of Mechanical Engineers, 2008.
- Jankovic, M., and Magner, S. W., “Cylinder Air-Charge Estimation for Advanced Intake Valve Operation in Variable Cam Timing Engines”. JSAE Review, 22:445-452, 2001.
- Benejes, J., Reyes, E., and Lujàn, J. M., “Modelling Study of the Scavenging Process in a Turbocharged Diesel Engine with Modified Valve Operation”. Proceedings of the Institution of Mechanical Engineers, 210(4):383-393, 1996.
- Martensson, J. and Flardh, O., "Modeling the Effect of Variable Cam Phasing on Volumetric Efficiency, Scavenging and Torque Generation," SAE Technical Paper 2010-01-1190, 2010, doi:10.4271/2010-01-1190.
- Jankovic, M., Frischmuth, F., Stefanopoulou, A., and Cook, J. A., “Torque Management of Engines with Variable Cam Timing”. IEEE Control Systems, 18(5):34-42, 1998
- Lee, D., Jiang, L., Yilmaz, H., and Stefanopoulou, A. G., “Air Charge Control for Spark Ignition Engines with Internal Exhaust Gas Recirculation”. In Proceedings of the 2010 American Control Conference, pp 1471-1476. IEEE, 2010.