Patent ID: 9429322
Filing Date: 2016-08-30
CPC Classification: F23Q,H01T

Claim Text:
1. A glow plug comprising: a tubular housing extending in a direction of an axis; and a rod-shaped heater whose forward end portion projects from a forward end of the housing and whose rear end portion is held inside the housing, characterized in that the housing has a forward end portion having an outer peripheral surface whose diameter increases toward the rear end side with respect to the axial direction, the forward end portion coming into contact with a seat surface formed on an internal combustion engine when the glow plug is attached to a through-hole provided in the internal combustion engine; the outer peripheral surface of the forward end portion includes a plurality of contact surfaces which differ in imaginary line angle from one another, the imaginary line angle of each contact surface being an angle which is formed, as viewed on a cross section including the axis, between two straight imaginary lines connecting inflection points of the contact surface at opposite ends of the contact surface; and at least one of the plurality of contact surfaces is a curved surface which bulges outward, wherein in the plurality of contact surfaces, an imaginary line angle of contact surface provided on the most forward end side with respect to the axial direction is 130° to 110°, and an imaginary line angle of contact surface provided on the most rear end side with respect to the axial direction is 70° to 50°.