Patent ID: 9664388
Date: 2017-05-30
CPC Classifications: F23Q,H05B,Y10T

Claim:
1. A glow plug comprising: a sheath tube which is formed of a metal and which extends in an axial direction and has a closed front end; a heating element accommodated within the sheath tube; insulating powder which fills an interior of the sheath tube so as to surround the heating element; a rod-shaped lead which is formed of a metal and which is connected to the heating element and inserted into the sheath tube from a rear end of the sheath tube; and a seal member which is located in a seal portion of the sheath tube formed at the rear end of the sheath tube and which hermetically seals a gap between the sheath tube and the lead; wherein the sheath tube is formed to have a substantially uniform outer diameter over an axial range including and extending beyond a range where the seal portion is formed, wherein the seal portion includes a spot-faced portion, an inner diameter of the spot-faced portion being larger than a remainder of the sheath tube, wherein the seal member is disposed rearward with respect to a front end of the spot-faced portion, wherein the sheath tube has an engagement projection formed at the seal portion and deformed so as to protrude radially inwardly, and wherein a thickness of the engagement projection when viewed in a cross-section taken in a direction perpendicular to an outer wall of the sheath tube at the engagement projection is greater than a thickness of an entire remainder of the seal portion of the sheath tube when viewed in a cross-section taken in a direction perpendicular to an outer wall of the sheath tube outside of the engagement projection.