| 摘要 |
PROBLEM TO BE SOLVED: To provide a glow plug for four-cycle model engine which is strong against vibration and impact, in which cooling of a heater coil 20 is restrained in a low-speed rotation region, and the heater coil 20 is not overheated in a high-speed rotation region. SOLUTION: In a hollow part 10d in the inside of a plug housing 10, a center electrode 12 is inserted so that its tip end comes nearly to the tip end of the plug housing 10, and the electrode is fixed in an electrically insulated state. One end of the heat coil 20 is connected electrically to the tip-end face of the electrode 12, and the other end thereof is fixed to be electrically connected to the tip end edge of the housing 10. A cylindrical member 22 is fit in, and fills the space between the internal periphery of the inside hollow part 10d of the housing 10 and the outside periphery of the tip end of the electrode 12. The cylindrical member 22 is composed of a material of alumina having insulating property and a good thermal conductivity.
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