The Next Generation BOSCH Common Rail Injectors with Digital Rate Shaping – A Key Factor for Meeting Future Requirements

Authors

Dr. R. Maier, J. Warga, Dr. T. Pauer,
Dipl.-Ing. J. Gerhardt, Dr. M. Krüger, Robert Bosch GmbH, Stuttgart

Year

2012

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 735

Summary

Over the entire operating map of a Diesel engine there is a complex relationship between fuel consumption, exhaust and noise emissions. Pilot injections (PI) can be applied to optimize the combustion process – with the degrees of freedom being limited for conventional PI strategies. However, these limitations can be overcome by launching the pilot injection immediately before the main injection. This digital injection pattern (pilot injection / main injection) results in a "soft" and uninterrupted combustion process, reducing noise emissions and permitting a further reduction in emissions and fuel consumption. This Digital Rate Shaping strategy places new requirements onto the injector in terms of the time interval between pilot injection and main injection, the precision of quantities injected, and reproducibility. Development of the new solenoid-valve injector CRI2-20 which uses a new basic concept with an integral high-pressure volume and a "long-needle" design was targeted to meet these requirements.

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