This content is not included in your SAE MOBILUS subscription, or you are not logged in.
A New Rotary Valve for 2-Stroke Engines Enabling Over-Expansion
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 05, 2016 by SAE International in United States
Annotation ability available
One way to increase efficiency and performance of 2-stroke engines is the addition of an exhaust valve to control the opening/closure of the exhaust port. With this implementation it is possible to change the exhaust timing for different conditions. However, conventional systems cannot change the exhaust opening and closure timings independently. The work herein presented shows the development of a new exhaust rotary valve enabling the control of the opening independently from the control of the closure of the exhaust port. The study is based on kinetic and thermodynamic analysis.
Some manufacturers use exhaust rotary valves but none of them performs a fully rotary motion. This kind of motion has various benefits such as smoothness and most notably the ability to control both the opening and the closure timing of the exhaust independently.
Regarding the kinematic analysis, a simple model was created to determine the most suitable valve angles. This combines the kinematic of the piston with the kinematic of the valve in order to determine the required valve angles to perform the required exhaust timing. With this model the authors were able to obtain the valve parameters for different engine conditions and visualize geometry limitations of the valve for each engine event.
For the thermodynamic analysis the authors were able to use the data from the referred kinematic model to create a 3D model of the engine. The 3D model was then implemented using the software CONVERGE CFD which simulated the flow and thermal effect of the valve on the engine behaviour. The simulations were performed for a single engine geometry but with different valve conditions/geometry and different compression ratios. It was concluded that indeed it is possible to effectively implement this kind of valve and achieve the intended over-expansion effect.
CitationMartins, J., Pereira, C., and Brito, F., "A New Rotary Valve for 2-Stroke Engines Enabling Over-Expansion," SAE Technical Paper 2016-01-1054, 2016, https://doi.org/10.4271/2016-01-1054.
- Martins, Jorge (2013). Internal Combustion Engines (in Portuguese) (4th edition). Porto: Publindústria
- Yamaha (2009). Yamaha technology 1980: YPVS (Yamaha Power Valve System). Available: http://www.yamaha-motor.eu/designcafe/en/about-design/technology/index.aspx?segment=About%20-Design%20-%20Technology&view=article&id=440980, Last accessed 2nd March, 2015
- Anderson, S. (1986). Exhaust Power Valves. Cycle World Magazine, April, 89-94.
- Zim. Korn. (2002). Schematics. Available: http://www.nsr125.com/schem.htm, Last accessed 1st May, 2015
- Dan (1999). Power valves. Available: http://www.dansmc.com/powervalve.htm, Last accessed 6th April, 2015
- MARTINS, J.J.G., et. al. (2004). Martins, J., Uzuneanu, K., Ribeiro, B., and Jasasky, O., "Thermodynamic Analysis of an Over-Expanded Engine," SAE Technical Paper 2004-01-0617, 2004, doi:10.4271/2004-01-0617.
- Turner, J. W. G., Blundell, D. W., Larkman, D. B., Burke, P., Pearson, R. J., Richardson, S., Green, N. M.,Brewster, S., Kenny, R. G. and Kee, R. J.. (2009). Omnivore: an automotive flex-fuel 2-stroke engine with variable compression ratio, variable charge trapping and direct fuel injection. In: Meche.E I.. Internal Combustion Engines: Performance, Fuel Economy and Emissions Conference, 2009, 2009-12-08 - 2009-12-09, London.
- MARTINS, J J G (2009). Process for Efficiency Improvement of a 2-Stroke Engine with Rotary Valve on the Exhaust, Portuguese Patent nº103663, 9th June, 2009, (published in "Boletim da Propriedade Industrial no. 115/2009", 17th July 2009)
- Issa, R. I. (1986). Solution of the Implicitly Discretised Fluid Flow Equations by Operator-Splitting, Journal of Computational Physics, Volume 62.
- Lindemann, F. A., et. al. (1922). Discussion on 'the radiation theory of chemical action', Transaction of the Faraday Society, 17:598.
- Han, Z., and Reitz, R. D. (1995). Turbulence Modeling of Internal Combustion Engines Using RNG k-ϵ Models, Combustion Science and Technology, Volume 106.
- Amsden, A. A. (1997). KIVA-3V: A Block Structured KIVA Program for Engines with Vertical or Canted Valves, Los Alamos National Laboratory Report No. LA-13313-MS.
- Heywood, J. B. (1988). Internal combustion engines fundamentals. New York: McGraw-Hill, Inc.