1998-08-11

Can the Best Fuel Economy of Today's Engines Still Be Improved? 981912

Direct injection into open chambers of Diesel- and S.I.- Engines is considered by the experts of automotive engineering worldwide as the best way for future economy and ecology engines [1]. Beside of the best fuel saving passenger cars driven by Diesel engines, advanced Diesel like Stratified Charge Engines as the CCSC (Controlled Combustion Stratified Charge) and the MESC (Mixture Exhaust Stratified Charge) -Engines open the way for future developments. Both engines work with the following new elements:
  • Air assisted injection for the formation of the combustible mixture in the small cavities of prechambers, where the load control is achieved by the quantity of the injected fuel without the need of throttling the charge of the main chamber as common in today's SI engines.
  • Pulsed Jet Combustion, where at first in small cavities of prechambers a rich mixture gets ignited. Afterwards pulsed jets of burning gases, at least two jets moving in opposite directions, impinge each other in the middle of the cylinder, where after a sudden multipoint ignition a fireball-combustion of lean mixture takes place, surrounded by a layer of inert gases close to the cylinder wall.
  • Stratification of residual gas, in order to reach an isolation of the burning lean mixture to avoid heat losses and flame quenching at the wall. In this procedure only that amount of formerly burnt residual gas gets discharged from the cylinder, which equals the amount of the newly formed burnt gas coming from the fireball.
In a cooperative investigation at the Technical University Poznan and the Institut für Fahrzeugbau in Wolfsburg, sponsored by the Volkswagen Foundation, theoretical and experimental results showed the successful application of the MESC-principle on reciprocating engines.

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