A New Piezo Common Rail Injector with Direct Drive and Closed Loop Functionality: Concept and Engine Benefit

Authors

Dipl.-Ing. S. Bauer, Dr.rer.nat. H. Zhang, Dipl.-Ing. R. Pirkl, Dr.-Ing. A. Pfeifer, Dr.-Ing. K. Wenzlawski, Dipl.-Ing. H.-J. Wiehoff, Continental AG, Regensburg

Year

2008

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 672

Summary

In the conflict of reduction of emissions and fuel consumption as well as the cost of production, the optimum balancing of measures to reduce emissions engine out or at the tailpipe plays a vital role.


Compared to the current optimised, more robust design of intake and combustion system for EU6, the fuel injection systems has a large influence on sample-to-sample deviation of exhaust and noise emissions, due to its mixture formation characteristics but also its production tolerances. Within the injection system the injector concept disproportionally determines engine performance and emission as well as injection system cost.


The new 2000 bar piezo common rail injector with direct drive provides through its concept for the first time a closed loop injector control. This constitutes an "emissions reduction module", which provides multiple features for reproducible rate shaping as an alternative to the commonly known multiple injection patterns. Via the detection of nozzle needle position during injection the control loop for the fuel mass can for the first time be closed. The drift and sample-to-sample deviations which remain in spite of the robust hydraulic design will be recognised and compensated for safely. Therefore - from the overall system point of view – the use of cost intensive additional closed loop control circuits on the basis of cylinder pressure or Lambda signal can be omitted for conventional Diesel combustion.


In this presentation the chosen direct drive concept as well as the fuel mass control loop will be introduced. The hydraulic performance will be discussed as well as the first results from single and multi cylinder engines. These will confirm the significantly extended potential of this injector concept to fulfill future requirements compared to current solutions.

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