| 摘要 |
PURPOSE: A glow plug is provided to lengthen the life span of the glow plug despite the long time use and to improve the shock resistance and vibration resistance despite the length of the glow plug. CONSTITUTION: A glow plug includes an inner pole(1) and a ceramic heating rod(3) disposed in and fixed to an outer shell(2) at uppermost and lowermost pole fixed portions(A,C) and a heating rod fixed portion(D). A ratio of L2/L1 is larger than 2, where L1 is a distance from the lower end of the inner pole to the lower end of the fixed portion(C), and L2 is a distance from the lower end of the inner pole to the lower end of the fixed portion(A). A ratio of L3/L4 is smaller than 15, wherein L3 is a distance from a middle point between the lower end of the inner pole and the upper end of the heating rod to the lower end of the fixed portion(C), and L4 is a distance from the above middle point to the upper end of the fixed portion(D).
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