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US 2006/0066196 A1Published application
Spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorAkira Suzuki
Life of this patent
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Abstract
A spark plug having a packing interposed between an insulating porcelain and a metallic shell, wherein Young's modulus G of the material forming the metallic shell 50 and Young's modulus F of the material forming the packing 80 satisfies the relation of 7.4×1010 Pa is less than or equal to F is less than or equal to G minus 5×1010 Pa.
Claims5
A spark plug comprising:
- a center electrode for spark discharge at its own leading end having a central axis;
- an insulating porcelain having an axial hole extending in a direction along said central axis of the center electrode, said porcelain holding the center electrode inside of the axial hole and having an outwardly projecting step portion;
- a metallic shell surrounding the insulating porcelain in the radial direction, for tightening and holding the outer circumference of the insulating porcelain, said shell having an inwardly projecting step portion;
- and
- an annular packing interposed between the step portion of the insulating porcelain and the step portion of the metallic shell for sealing engagement therewith, said packing formed of a material having a Young's modulus F (Pa) and said metallic shell formed of a material having a Young's modulus G (Pa) wherein
- 7.4×1010 (Pa) is less than or equal to F is less than or equal to G minus 5×1010 (Pa), and
- the tensile strength of the material of the packing is 400 MPa or more.
4 more elements
Dependencies are inferred from the claim text.