Patent ID: 7388323
Filing Date: 2008-06-17
Classification: H01T

Abstract:
1. A spark plug comprising: an insulator having a through hole extending in an axial direction, said through hole including a first portion and a second portion provided on a rear end side of said first portion and having a larger diameter than that of said first portion; a center electrode provided in said first portion of the through hole of said insulator; an external terminal provided in said second portion of the through hole of said insulator; a sintered ceramic resistor provided in said second portion of the through hole, said sintered ceramic resistor comprising a sintered body of a conductive ceramic, connecting said center electrode and said external terminal electrically, and having a length in an axial direction being 40% or more of a length in an axial direction of said second portion of the through hole; and a conductive sealing portion comprising a glass component and a conductive component, and fixing and electrically connecting a rear end of said center electrode and a leading end of said sintered ceramic resistor, wherein a distance between a rear end of said center electrode and a leading end of said sintered ceramic resistor is 0.5 mm to 1.5 mm.