Spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorsTsutomu Shibata, Hiroyuki Tanabe
Life of this patent
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Abstract
A spark plug including: an insulator having a through hole extending in an axial direction, the through hole including, a first portion and a second portion provided on a rear end side of the first portion, the second portion having a larger diameter than that of the first portion; a center electrode provided in the first portion; an external terminal provided in the second portion; and a sintered ceramic resistor provided in the second portion. The sintered ceramic resistor is formed from a sintered body of a conductive ceramic, connecting the center electrode and the external terminal electrically, and having a length in an axial direction of 40% or more of a length in an axial direction of the second portion of the through hole.
Claims8
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;
- and
- a sintered ceramic resistor provided in said second portion of the through hole, 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.
Dependencies are inferred from the claim text.