| 摘要 |
PROBLEM TO BE SOLVED: To provide a glow plug capable of maintaining a stable connection state between a middle axis whose material is softer than a connection terminal and the connection terminal.SOLUTION: A female thread part 54 of a connection terminal 5 is screwed to a male thread part 33 of a middle axis rear end part 32 of a middle axis 3 whose Vickers hardness is lower than the material of the connection terminal 5, and an outer peripheral surface of a fixing part 52 is caulked inward in radial direction, thus a caulking part 55 is formed. Outside diameters X of portions A-C corresponding to the caulking part 55 are smaller than an outside diameter Y of not-corresponding portions D and E. At the portion A, slopes on both sides of the thread ridge of the male thread part 33 tightly contact the thread ridge of the female thread part 54. At portions B-E, a slope on the side opposite to the portion E of the thread ridge of the male thread part screw part 33 respectively tightly contacts to the thread ridge of the female screw part 54. The connection terminal 5 is surely fixed to the middle axis 3 in the direction of axial line O, and the tightly contacting state between the slopes of the threads extends a long way in conical state, to assure a wide contact area, resulting in stable electrical connection. |
