GLOW PLUG, ITS PRODUCTION PROCESS AND ION CURRENT DETECTOR

摘要

The present invention is to provide a glow plug (1) with an ion current detecting function, which is mounted in a combustion chamber of a Diesel engine. The glow plug includes an insulator (8); a heating element (6) embedded in the insulator and energized through a pair of lead wires (11a, 11b) to generate heat; and an ion current detecting electrode (14) embedded in the insulator with a portion exposed into a flame in the combustion chamber so that an ionization state in the flame can be detected. The heating element of the glow plug promotes ignition and combustion of fuel in the combustion chamber (7) due to its heating action caused when running the heating element hot. The ion current detecting electrode detects an ionization state in the combustion flame. When detecting ion current, the ion current detecting electrode and the adjacent inner wall of the combustion chamber form two electrodes for capturing positive and negative ions existing between both when burning the fuel. In such structure, the ion current can be detected precisely in spite of very simple structure. It is therefore possible to effectively use the information for combustion control. Further, since the ion current detecting function is added to the glow plug, an inexpensive ion current detecting sensor can be provided.