Spark Plugs for Gasoline Direct Injection Engines

The direct injection (DI) gasoline engine has drawn considerable attention recently for energy savings and emission reductions.

Compared with current port fuel injection (PFI) engines, DI engines are designed to have high specific power output, low fuel consumption and low emissions at the same time. Among others a feature of the DI gasoline engine is its capability to freely alter the state of combustion from homogeneous to stratified combustion at different load conditions. Engines with high power density such as the DI engine, are also prone to knock. To suppress engine knocking a flexible and precise combustion control mechanism is required.

The paper being presented describes some of the characteristics required for spark plugs utilized in DI gasoline engines. The unique features are: the firing point is set slightly deeper in the combustion chamber; the plug has increased temperature resistance; the fuel mixture is stratified for low and medium engine speeds; and the plug has anti-carbon fouling properties with self-cleaning capability.

The paper presents details on the spark plugs developed for DI gasoline engine applications including the performance and experimental results.