Results of Combustion Optimization by Use of Multihole Nozzles in Modern Passenger Car Diesel Engines

Authors

Dr.-Ing. U. Dohle, Dr.-Ing. M. Krüger, Dipl.-Ing. D. Naber, Dipl.-Ing. J. O. Stein, Dipl.-Ing. Y. Gauthier, Robert Bosch GmbH, Stuttgart

Year

2006

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 622

Summary

A possibility to improve air/fuel mixture formation without deterioration of efficiency at higher engine load by using smaller nozzle holes could be Multihole Concepts with two hole rows. These concepts are characterized by big degrees of freedom concerning spray orientation hydraulic layout, number of spray holes and twist angle between top and bottom hole row. Hence based on experience of Robert Bosch GmbH a nozzle matrix of highest potential Multihole variants have been defined and systematically investigated to find out an optimum layout of the aforementioned parameters. The optimized Multihole variant has an inline configuration of the nozzle holes with comparable big distance between the hole rows and a convergent spray orientation with identical impact point at the piston bowl wall. Comparing the results of this Multihole nozzle concept with the results achieved with an optimized combustion system equipped with conventional nozzle pointed out that comparable rated power is reachable with disadvantages in middle part load NOx- and particulate emissions and advantages in low part load HC-emission. Thus no overall improvement of compromise between specific power respectively high load efficiency and low emission is recognizable.

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