This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Fundamental Characteristics of an Air-Assisted Direct Injection Combustion System as Applied to 4-Stroke Automotive Gasoline Engines
ISSN: 0148-7191, e-ISSN: 2688-3627
Published March 06, 2000 by SAE International in United States
Annotation ability available
Event: SAE 2000 World Congress
Gasoline direct injection technology is rapidly evolving. At present, there does not exist a dominant combustion system, however many believe that the ultimate system will be spray or jet guided. These combustion systems rely on an ignitable mixture being promoted directly from the injection source to the spark plug gap location. Very small droplet sizes, coupled with low penetration rates and diffuse sprays, characteristic of air-assisted direct injection systems, are ideally suited to these spray guided combustion systems. The ability of the air assisted system to function with the spark plug directly in the injected spray without plug fouling problems is testament to the quality of fuel preparation enabled by the dual fluid injection process.
This paper presents the findings of some fundamental characterisation of Orbital's low pressure air-assisted, spray guided combustion system, including effects of injection pressure, injected gas composition, and in-cylinder charge motion. The results presented demonstrate the ability of the system to operate in highly stratified conditions at very lean A/F ratios with an injection pressure of only 6.5bar. As well, the direct injected air is identified as playing an important role at part load conditions by increasing combustion stability when using high EGR levels, enabling the simultaneous achievement of low fuel consumption and low raw engine emissions. The injected air is also instrumental in providing “soft” stratification gradients which result in excellent stability and high levels of robustness, both of which are important in ensuring easy transition from engine testcell to vehicle platforms.
CitationCathcart, G. and Zavier, C., "Fundamental Characteristics of an Air-Assisted Direct Injection Combustion System as Applied to 4-Stroke Automotive Gasoline Engines," SAE Technical Paper 2000-01-0256, 2000, https://doi.org/10.4271/2000-01-0256.
- Niefer, H.G., Frey, J., Karl, G., Krämer, S.,“Der DE-Ottomotor: Quo vadis - wohin führt der Weg? (The DI Gasoline Engine: Quo vadis - where does the road lead?),” Vienna Motor-Symposium, 1999.
- Fraidl, G.K., Piock, W.F., Holy, G., Unger, E.M., Wirth, M.,“Otto - Direkteinspritzung - das Verbrauchskonzept für EURO 4 (Gasoline Direct Injection - The Low Fuel Consumption Concept for EURO 4,” Vienna Motor-Symposium, 1999.
- Houston, R., Cathcart, G., “Combustion and Emissions Characteristics of Orbital's Combustion Process Applied to Multi-Cylinder Automotive Direct Injected 4-Stroke Engines,” SAE 980153.
- Benson, R.S., Whitehouse, N.D.,“Internal Combustion Engines,” 1, Pergamon Press, 1979.
- Heywood, J.B.,“Internal Combustion Engine Fundamentals,” McGraw-Hill Book Co., 1988.
- Stone, C.R., Beckwith, P.,“A turbulent combustion model used to give insights into cycle-by-cycle variations in spark ignition engine combustion,” C448/013 IMechE, 1992.
- Poola, R.B., Stork, K.C., Sekar, R., Callaghan, K., Nemser, S., “Variable Air Composition with Polymer Membrane - A New Low Emissions Tool,” SAE 980178.
- Lavoie, G.A., Heywood, J.B., Keck, J.C.,“Experimental and theoretical study of nitric oxide formation in internal combustion engines,” Combustion Science and Technology 1, 313, 1970.
- Blumberg, P.N.,“Nitric Oxide Emissions From Stratified Charge Engines: Prediction and Control,” Combustion Science and Technology, Vol 8, 5-24, 1973.
- Iwamato, Y., Noma, K., Nakayama, O., Yamauchi, T., Ando, H.,“Development of Gasoline Direct Injection Engine,” SAE 970541.
- Harada, J., Tomita, T., Mizuno, H., Mashiki, Z., Ito, Y., “Development of Direct Injection Gasoline Engine,” SAE 970540.
- Grigo, M., Schmidt, R., Wolters, P.,“Charge Motion Controlled Combustion System for Direct Injection SI Engines,” Advanced Engine Design & Performance, GPC '98.
- Preussner, C., Döring, C., Fehler, S., Kampmann, S.,“GDI: Interaction Between Mixture Preparation, Combustion System and Injector Performance,” SAE 980498.