| 摘要 |
PROBLEM TO BE SOLVED: To provide a long life glow plug in which the diameter of a heater is 4.0 mm or shorter and a heater part has a length of 15 mm or longer and a long after glow power supply can be realized. SOLUTION: The glow plug 100 comprises a metallic heater case 20 having a small diameter part 22 whose diameter is 4 mm or less and whose length is 15 mm or more at one end and a large diameter part 24 at the other end, a first coil 30 buried in the small diameter part 22 through insulating powder 26 and having one end electrically conducted to the heater case 20, a second coil 40 buried in the small diameter part 22 through the insulating powder 26 and having one end connected to the first coil 30 and insulated from the heater case 20 and a housing 10 for enclosing the large diameter part 24 to hold the heater case 20. The maximum temperature part of the heater case 20 after 60 seconds when rated voltage is applied thereto is located in the heater case 20 corresponding to the first coil 30.
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