| 摘要 |
PROBLEM TO BE SOLVED: To suppress damage of a heating coil to improve durability of a glow plug.SOLUTION: A glow plug 10 includes a heater element 800 including a sheath tube 810 and a heating coil 820, and the tip of a diameter contraction part 865 in the sheath tube 810 and the tip of the heating coil are welded. The outer diameter of a straight part 860 of the sheath tube 810 is 4.3 mm or less. On the external surface of the sheath tube 810, the whole outer periphery of a melting part 850 formed by melting the sheath tube 810 and the heating coil 820 is included in the diameter contraction part 865. When the melting part 850 and the heating coil 820 are projected in an axial direction with respect to a virtual plane vertical to the axial direction, the whole projection image of the heating coil 820 exists in an area where the melting part 850 has been projected. |
