New Methods for the Selection of Injectors and the Start-Tuning of Gasoline Engines with Port Injection

Authors

Dipl.-Ing. M. Frank, Dipl.-Ing. M. Gesk, Dr.-Ing. W. Samenfink, Dipl.-Ing. J. Gerhardt, Robert Bosch GmbH, Stuttgart; Dipl.-Ing. B. Hackl, Dipl.-Ing. M. Urbanek, Dr. P. Hofmann, Univ.-Prof. Dr. B. Geringer, Technische Universität Wien

Year

2006

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 622

Summary

To achieve the emission limits in the future, the potential of the mixture formation during the cold start has to be raised. But such improvements must not decrease the cost/profit balance of gasoline engines with port fuel injection. Analyses with different mixture formation systems have been made. Some conventional standard injectors as well as injectors with reduced Sauter Mean Diameter (SMD) have been analysed concerning their potential to reduce the HC emissions during the cold start. Additionally some injectors whose injection orifice plate was fabricated using a new technology were tested. With a high and low pressure indication, a 1-D gas change analysis as well as measurements with a fast flame ionization detector, the crank angle based HC mass flow was deduced. To evaluate the different injectors next to the HC emissions the characteristics of the combustion, the speed rise and the wall-applied fuel mass were analysed. The reduction of the SMD leads to an improvement of the mixture formation and the homogenization, so that with emaciation the energy conversion with an optimal efficiency of the combustion during the first cycles was much faster. Next to the lower HC emissions the peak pressure was higher, the speed rise was faster and efficient catalyst heat methods like late ignition angles could be realized earlier.

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