Spark plug for an internal combustion engine
AssigneeNgk Spark Plug Co., Ltd.
InventorsTomoaki Kato, Akio Sakura, Takahiro Suzuki
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Abstract
In a spark plug, a cylindrical metal shell is provided whose inner wall has a ledge portion on which an insulator rests through its seat portion. The insulator has an axial bore in which a center electrode is placed whose front end has a heat-resistant metal tip. A ground electrode is provided to form a spark gap with the noble metal tip of the center electrode. The insulator forms an insulator nose which measures less than 15 mm in length. The heat-resistant metal tip measures less than 0.8 mm in diameter. A space between an outer surface of the center electrode and an inner wall of a front open end of the axial bore is defined to be more than 0.1 mm in width.
Claims8
In a spark plug including a cylindrical metal shell whose inner wall has a ledge portion on which an insulator rests through its seat portion, the insulator having an axial bore in which a center electrode is placed whose front end has a heat-resistant metal tip, and a ground electrode provided to form a spark gap with a noble metal tip of the center electrode;
- the spark plug comprising:
- the insulator forming an insulator nose which measures less than 15 mm in length;
- the heat-resistant metal tip measuring less than 0.8 mm in diameter;
- and
- a space between an outer surface of the center electrode and an inner wall of a front open end of the axial bore being not less than 0.1 mm in width L.
Dependencies are inferred from the claim text.