Modern DI Diesel Pistons – Development and Technologies

Authors

Dr.-Ing. W. Ißler, Dipl.-Ing. E. Kopf, MAHLE GmbH, Stuttgart

Year

2004

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 566

Summary

High speed direct injection (HSDI) Diesel engines for automotive applications have already been introduced into production with a rating of more than 60 kW/l specific power. To attain such high power, appropriate development activities in piston technology and design as well as materials is required. In addition, bmep significantly higher than 20 bar calls for most efficient piston cooling. Increasing peak cylinder pressure load must be sustained by an appropriately designed piston structure. Simulation tools are widely used to optimize system behaviour within the power cell module by numerical parameter studies. As an example, the modern combustion pressure characteristics may induce increased load on the piston-liner system. Appropriate simulation tools accounting for component stiffness allow to analyse such effects and were validated by measurements in the operating engine. Aluminium pistons without or with local fiber reinforcement (MMC) and eventually shrink-fitted bushings and in addition - primarily for heavy duty engines – forged steel pistons, mostly single-piece designs, are state of the art to safely allow peak cylinder pressures in excess of 180-200 bar. In the future the need to employ single-piece forged steel pistons as they are successfully produced for different off-highway and truck engines nowadays, might as well arise for HSDI applications.

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