Search Results

The design of spark plugs, critical for igniting the gas mixture in the combustion chamber, must catch up with the latest advances in automotive engine development because many improvements for higher efficiency and lower emissions make combustion more difficult to initiate. Spark plugs must maintain their function in both below freezing environments and high speed, high temperature operation. The performance of a spark plug is characterized by the shape of its firing end exposed in the combustion chamber and the layout of the insulator nose in the metal shell. This paper summarizes recent requirements for spark plugs, proposes a new firing end shape, and evaluates its performance. The relationship between geometric configuration and performance are evaluated on an actual engine. The results demonstrate improved spark plug performance, especially under the most extreme temperature conditions.

For the future high power output and low emission engine, the spark plugs need to be improved ignition performance and high thermal resistance with reduced sizes. To accommodate these requirements a new spark plug has been developed with new material and better configurations.

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.

NGK Spark Plug has developed new Multi Spark Ignition (MSI) system to improve fuel economy and engine cold start performance. Since engine ignition is the very first stage of reaction process, which leads to subsequent combustion and emission formations, it plays an important function to determine the efficiencies of power conversion and characteristics of exhaust gas. In addition to the conventional function of combustible gas ignition, the spark plug detects ion current surrounding the plug gap to analyze state of combustion. The developed MSI system demonstrated significant performance advantages on engine ignitions and detection of combustion characteristics for engine optimal control.