[...]... particular application before invoking this strategy 2.3.4 Air-assisted injection A significant number of references exist for the application of air-assisted injectors to gasoline direct- injection in two-stroke engines [102-120,317] and PFI engines [38,82,121-124,374] Unfortunately, the number dealing with four-stroke DI gasoline engines is much more limited [71,72,125-129], although it is important... is comparable to PFI In addition to the above, reliable and efficient hardware and control strategies for gasoline direct injection technology will have to be developed and verified under field conditions For the same reasons that port fuel injection gradually replaced carburetor and throttle-body injection, a GDI combustion configuration that will be an enhancement of one of the concepts outlined in... operation, the injection system should provide the capability for rapid injection late in the compression stroke into an ambient pressure of up to 1.0 MPa, which requires a relatively high fuel injection pressure The fuel injection pressure has been determined to be very important for obtaining both effective spray atomization and the required level of spray penetration A higher fuel injection 445 F... variable injection pressure is a viable system strategy A wide range of gasoline, having variable alcohol content, sulfur content and driveability indices are available in the field This quality range makes it a necessity that a robust fuel system be developed and proven for GDI production engines [296] To avoid dilution of the engine oil, most GDI fuel pumps are lubricated with gasoline [373] However, gasoline. .. air flows through the valve opening For direct injection in both GDI and diesel engines, however, the mixture preparation time is significantly less than is available for port fuel injection, and there is much more dependence on the primary spray characteristics to prepare and distribute the fuel to the optimum locations It is well established that a port-injected gasoline engine can operate quite acceptably... function of fuel injection duration and injection pressure are shown in Fig 22 The maximum penetrations of both the initial sac spray and the main spray increase linearly as the injection duration increases For injection corresponding to the idle operation, the axial penetration of the initial sac spray is larger than that of the main spray, with both exhibiting less dependence on the injection pressure... best fuel economy is obtained at 8.0 MPa This may be an injection rate effect rather than a mean-drop-size effect, as a lower fuel injection pressure yields comparatively longer fuel injection duration, thus providing more time for fuel evaporation and dispersion At higher engine speeds, a higher fuel injection pressure combined with a shorter fuel injection duration is reported to be effective in avoiding... spray cone, and impacts directly on the piston crown for early injection An important point is that observations for an injection timing of 80 ° ATDC on the intake stroke confirmed that there is no major impingement of the fuel spray upon the piston except for this initial slug of fuel from the sac volume For earlier injection timings, however, a large portion of the main spray directly impacts the piston... from carburetor to throttle-body injection, then to simultaneous-fire PFI, and more recently to phased-sequential-fire PFI The result is that today the sparkignited PFI engine remains the benchmark standard for automobile powerplants [38] In order to displace this standard, the practical development targets for future GDI engines, as compared to current best-practice PFI engines, are as follows [42]:... combustion, the fuel spray characteristics are of significant importance to direct- injection gasoline combustion systems Parameters such as the spray cone angle, mean drop size, spray penetration, and fuel delivery rate are known to be critical, and the optimum matching of these parameters to the airflow field, piston bowl geometry and spark location usually constitute the essence of a GDI combustion system . direct injection gasoline direct injection gasoline direct-injection spark-ignited gasoline direct injection gasoline direct injection spark-ignited direct-injection 1. Introduction 1.1. Overview. PROGRESS IN ENERGY AND COMBUSTION SCIENCE www.elsevier.com/locate/pecs Automotive spark-ignited direct-injection gasoline engines F. Zhao ~'*, M C. Lai ~, D.L. Harrington b aDepartment. PROGRESS IN ENERGY AND COMBUSTION SCIENCE An International Review Journal Automotive spark-ignited direct-injection gasoline engines Editors F. ZHAO, M C. LAI, D.L. HARRINGTON PERGAMON Published