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(11) | EP 0 648 978 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Ceramic glow plug |
(57) This invention provides a ceramic glow plug of current self-control type with a stable
strength and a high-temperature strength resistant to thermal shocks. In this ceramic
glow plug, the ceramic pipe (2) is secured to the hollow body (1) having the electrode
(10) and is formed with the conductive printed layer (8) on its outer surface. One
end of the pipe (2) is sealed by the ceramic filler (4) to form the hollow portion
(9) inside the pipe In the hollow portion (9) sealed with N2 gas, the tungsten wire (3) is installed, with one end (7) connected to the conductive
printed layer (8) and the other end (16) to the electrode (10). The outer circumferential
surface (13) of the pipe (2) is formed with the ceramic outer surface coating layer
(5). When the tungsten wire (3) and the conductive printed layer (8) are supplied
with electricity, the conductive printed layer (8) functions as the heater portion
(12) and the tungsten wire (3) as the current control portion (6). |