IGNITION PLUG AND METHOD OF MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To more reliably restrain the generation of corona discharge and enhance accuracy in detection of ionic current.SOLUTION: An ignition plug 1 includes a tubular main metallic shell 3 and an insulator 2 provided at an inner circumference of the main metallic shell 3 and including a rear end side trunk portion 10 which is formed at a rear end portion thereof and exposed from the rear end of the main metallic shell 3. The ignition plug 1 is configured such that the main metallic shell 3 and the insulator 2 are fixed together by means of a crimped portion 20 which is provided at a rear end portion of the main metallic shell 3 and bent radially inward. The ignition plug 1 is utilized for detecting ionic current. The ignition plug 1 has a filling member 31 with insulation properties which is filled into a space SP formed between the crimped portion 20 and the insulator 2. The filling member 31 covers the whole area in the circumference direction on at least a portion of the outer circumferential surface of the rear end side trunk portion 10 and the whole area of the rear end side surface 20A which is a part of the outer surface of the crimped portion 20 and is visually recognizable from the rear end side in the direction of an axial line CL1.