Usage of High Fuel Injection Pressures as a Powerful Tool for Improving Diesel Engine Efficiency

Autoren

Dr. Francesco C. Pesce, Dr. Alberto Vassallo,
General Motors Global Propulsion Systems, Turin;
Dr. Carlo Beatrice, Dr. Gabriele Di Blasio, Dr. Giacomo Belgiorno,
Istituto Motori-CNR, Neapel;
Dr. Giovanni Avolio, Dr. Oliver Kastner,
Continental Automotive GmbH, Regensburg

Zusammenfassung

The paper describes the results achieved in developing a new diesel combustion system for passenger car application that, while capable of high power density, delivers excellent fuel economy through combination of mechanical and thermodynamics efficiencies improvement.

The project stemmed from the observation that by increasing the fuel injection pressure is possible to increase the engine power density while maintaining the engine peak firing pressure constant. Conversely, it was conceived the idea that, by leveraging the high fuel injection pressure of last generation common rail systems, is
possible to reduce the engine peak firing pressure with great benefits on reciprocating and rotating components light weighting and friction, while keeping the power density at competitive levels.

Following extensive benchmark and analysis activities in order to identify the key design parameters to be optimized, an advanced injection system concept from Continental capable, at prototype level, of injection pressure >2500 bar maximum was selected and coupled to a prototype engine featuring GM-developed combustion
system.

The matching among the low compression ratio wide bowl, the in-cylinder charge motion, the highly efficient injector nozzle and the injection pressure have been thoroughly examined and experimentally parametrized. The tests confirmed the benefits of the employment of high fuel injection pressures as a way to reduce peak firing pressure requirements, combining competitive performance and excellent fuel efficiency with emissions and NVH requirements of last generation diesels for passenger car.

The paper discusses the engine power and efficiency sensitivities to the boundary conditions of the charging / exhaust systems, the available maximum fuel injection pressure and the mechanical base engine (in particular the peak firing pressure). Consequently, it develops a balanced set of targets for the entire system based on
such results.

Mitglieder-Login