Glow plug with glass coating over ion detection electrode

• US 6,326,595 B2
• Filed: 12/06/2000
• Issued: 12/04/2001
• Est. Priority Date: 12/08/1999
• Status: Active Grant

• Current Assignee: NGK Spark PLUG Company Limited
• Original Assignee: NGK Spark PLUG Company Limited
• Inventors: Taniguchi, Masato, Kimata, Hiroyuki
• Primary Examiner(s): Jeffery, John A.
• Application Number:
  US09/729,723
• Publication Number:
  US 20010009254A1
• Time in Patent Office: 363 Days
• Field of Search: 219/270, 219/544, 123/145.A, 123/145.R, 361/264-266
• US Class Current: 219/270
• CPC Class Codes: F02P 19/028 the glow plug being combined with or used as a sensor
• CPC Class Codes: F23Q 2007/002 with sensing means
• CPC Class Codes: F23Q 2007/004 Manufacturing or assembling methods
• CPC Class Codes: F23Q 7/001 Glowing plugs for internal-combustion engines

Abstract

A glow plug includes a metallic sleeve 1; a cylindrical metallic shell 2, which holds the metallic sleeve 1; a terminal electrode 3, which is attached into the cylindrical metallic shell 2 while being insulated therefrom; a ceramic heating member 4, which is fitted into the metallic sleeve 1; and a glass coating layer 5. In the glow plug, a portion of an ion detection electrode 411 is exposed at the surface of an insulator 44 of the ceramic heating member 4. The exposed portion is coated with a glass coating layer 5, which is formed in such a manner as to extend all around the insulator 44 of the ceramic heating member 4 and has a thickness of 10-200 μm and a softening point of not lower than 600° C.

Claims

1. A glow plug comprising a ceramic heating member which in turn comprises an insulator, a heating resistor disposed within said insulator, and an ion detection electrode disposed within said insulator, characterized in that a portion of said ion detection electrode is exposed through said insulator and the exposed portion is coated with a glass coating layer.

2. The glow plug as claimed in claim 1, wherein the glass coating layer covers the exposed portion and extends all around a circumference of said insulator.

3. The glow plug as claimed in claim 1, wherein the glass coating layer has a thickness of 10-200 μ

m.

4. The glow plug as claimed in claim 1, wherein the glass coating layer has a softening point of not lower than 600°

C.

5. The glow plug as claimed in claim 1, wherein said ion detection electrode and said heating resistor are made of the same material.

6. The glow plug as claimed in claim 1, wherein a portion of said ion detection electrode is exposed through an opening in said insulator.