Heater equipped spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorsTakahiro Suzuki, Yukihiko Ito
Life of this patent
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Abstract
A heater-equipped spark plug comprises an insulator having an insulator nose which holds thereon a center electrode in the vicinity of a free end of an axial bore, a lead wire arranged along a surface of the insulator, a heater formed on the insulator nose by baking a metal paste and connected to the lead wire; and a high softening-point glass layer covering and holding the heater in place with an alumina layer interposed between the high softening-point glass and the heater. Preferably, the alumina layer can have a thickness of 20-200 .mu.m and the high softening-point glass layer can have a thickness of 30-500 .mu.m.
Claims7
A heater-equipped spark plug comprising:
- an insulator having an insulator nose which holds thereon a center electrode in the vicinity of a free end of an axial bore;
- a lead wire arranged along a surface of said insulator;
- means, formed on said insulator nose, for heating said insulator nose, said means comprising a resistive heat generating element connected to said lead wire;
- and
- a high softening-point glass layer covering and holding said heater in place with an alumina layer interposed between said high softening-point glass layer and said heater.
Method of manufacturing a heating unit for a spark plug of the type having an insulator having an insulator nose which holds thereon a center electrode in the vicinity of a free end of an axial bore, a lead wire arranged along a surface of said insulator, a heater formed on said insulator nose and comprising a baked metal paste, said heater being connected to said lead wire, and a high softening-point glass layer covering and holding said heater in place with an alumina layer interposed between said high softening-point glass layer and said heater, said method comprising the steps of:
- applying a metal paste and an alumina paste on a resin sheet;
- adhering said resin sheet on an unsintered green body which forms said insulator nose;
- and
- sintering the metal paste and alumina paste together with said unsintered green body.
Dependencies are inferred from the claim text.