DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIRST EMBODIMENT The present invention will now be explained in detail with reference to the accompanying drawings.
In FIG.
1, numeral 1 designates an attaching (housing) section of a ceramic heater device and numeral 2 designates a heating section.
The attaching section 1 includes a metal housing 3 formed with a screw portion 3a and a central electrode 4 acting as an electrical terminal.
On the other hand, the heating section 2 includes a ceramic heater 5, an insulator 6 made of an electrically insulating ceramic material, and a pair of metal lead wires, 70, 80 embedded in the ceramic heater 5 and the insulator 6.
The ceramic heater 5 is formed as a U-letter configration and an end portion 60 of the insulator 6 is sandwiched between both ends (leg portions) 5a and 5b of the ceramic heater 5 as shown in FIG.
2.
Each end 71 and 81 of the metal lead wires 70 and 80 is electrically connected to the ceramic heater 5, respectively, as shown in FIG.
2.
Each of the other ends 72 and 82 of the metal lead wires 70 and 80 is exposed to the outer surface of the insulator 6.
The exposed end 72 of the metal lead wire 70 is electrically connected to a cap 9 made of a stainless steel by brazing and electrically connected to the central electrode 4 through a nickel wire 10.
The exposed end 82 of the metal lead wire 80 is likewise electrically connected to a sleeve 11 made of a stainless steel by brazing and the sleeve 11 is electrically connected to the housing 3 by brazing.
In FIG.
1, numerals 6a and 6b designate metallized layers (for example, Ag-solder, Ni-solder, Cu-solder), numeral 14 designates an electrically insulating ring, numeral 15 a heat-resistive seal ring made of rubber, numeral 16 an electrically insulating bush, and numerals 17 and 18 nuts.
In the above construction, when the central electrode 4 is connected to a positive terminal of an electric power source, while the housing 3 is connected to a negative terminal of the power source, electrical current flows through the nickel wire 10, the cap 9, the lead wire 70, the ceramic heater 5, the lead wire 80, the sleeve 11 and the housing 3, whereby the ceramic heater 5 is heated
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