JPS60203851A - Combustion detecting element and its production - Google Patents

Abstract

PURPOSE:To improve workability and to reduce cost by using a zirconia tubular body constituted of a zirconia green sheet which has an inside surface electrode and outside surface electrode to part of surfaces and is formed to a cylindrical shape. CONSTITUTION:Electrode patterns 12, 13 are formed of platinum paste to part of both surfaces of a zirconia green sheet 11 and the sheet is formed to a cylindrical shape and is calcined for 4hr at, for example, 1,650 deg.C to form a combustion detecting element having an inside surface electrode 22 and an outside surface electrode 23 to a zirconia tubular body 21. The combustion detecting element having the constant and uniform inside surface and outside surface electrodes is thus obtd. with a min. required electrode material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion detection element for detecting oxygen concentration in the combustion atmosphere of combustion equipment and a method for manufacturing the same.

Conventional Structures and Problems Conventionally, zirconia tubes have been used as combustion detection elements of this type, usually by rubber press molding or extrusion molding. Although electrodes on the outer surface of the body can be easily formed, patterning the electrodes on the inner surface of the body is extremely difficult, and sufficient electrodes cannot be obtained.

In addition, there are other problems such as adhesion of the electrode material to unnecessary parts, as well as the fact that the manufacturing process is time-consuming and costly.

The combustion detection element is shown in Figs. 1 and 2. In the figures, 1 is a silicone tube, 2 is an atmosphere-side inner electrode made of platinum or the like provided on the inner surface of the tube 1, and 3 is a tube. This is an external electrode on the combustion atmosphere side, which is made of platinum or the like and is provided on the external surface of the body 1.

However, in the zirconia tube 1 of the combustion detection element having such a configuration, the inner surface electrode 2 is formed on the zirconia tube 1 which is a sintered body by rubber press molding or extrusion molding, which has poor productivity.

For example, forming an electrode pattern using platinum paste is done using a brush or a dispenser, which is time-consuming and difficult to obtain a consistent pattern.
Even if an electrode pattern is easily formed, the inner electrode 2 is often formed on the entire surface, and it is extremely difficult to use when making zirconia tubes 1 of different dimensions, or because expensive platinum etc. are attached to unnecessary parts. This has the disadvantage that the combustion detection element has poor performance and high cost.

Purpose of the Invention The present invention has been made in view of these conventional problems, and it is possible to easily obtain zirconia tubes of different sizes, use a minimum amount of expensive platinum, etc., and is stable and has excellent workability. The present invention aims to provide an inexpensive combustion sensing element and a method for manufacturing the same.

Structure of the Invention In order to achieve this object, the combustion sensing element of the present invention and its manufacturing method are provided using a cylindrical zirconia green sheet having an inner electrode and an outer electrode on a part of its surface. It is characterized by using a zirconia tube body, and an electrode pattern is formed on a part of the surface of the zirconia green sheet, and the zirconia green sheet is processed into a cylindrical shape so that one end is overlapped.

It is characterized in that it is fired to form a zirconia tube.

DESCRIPTION OF EMBODIMENTS In the following, the present invention will be described as embodiments.
This will be explained in detail with reference to the drawings shown in FIGS.

That is, as shown in FIGS. 3 and 4, electrode patterns 12.1 are formed on parts of both surfaces of the zirconia green sheet 11.
3 is made of platinum paste, and this zirconia green sheet 11 is processed and formed into a cylindrical shape as shown in FIG.
By firing at 0° C. for 4 hours, a combustion sensing element having an inner surface electrode 22 and an outer surface electrode 23 on a zirconia tube body 21 was produced as shown in FIG.

Furthermore, the present invention also provides a novel method for manufacturing the above-mentioned combustion sensing element, the details of which will be described below.

That is, the method for manufacturing a combustion sensing element in the present invention is as follows:
An electrode pattern 12 was formed on a part of one surface of the zirconia green sheet 11 shown in FIG. 3 by screen printing with platinum paste and heated at 60°C.

After drying for a few minutes, an electrode pattern 13 was formed on a part of the other surface by screen printing with platinum paste, and the electrode pattern 13 was again
Dry at C for 30 minutes.

Next, as shown in FIG. 4, the zirconia green sheets 11 are rolled into a spiral cylindrical shape so that at least one end of the zirconia green sheets 11 is overlapped, and an organic solvent is applied to the surface of the overlapped zirconia green sheets 11. The cylindrical tube made of the zirconia green sheet 11 shown in FIG. 6 is obtained by melt-bonding.

After that, heat is removed to remove organic substances contained in the zirconia green sheet 11, and then 1 etso is heated in an oxidizing atmosphere.
'C, zirconia tube 21 shown in Figure 6 after firing for 4 hours
It is possible to manufacture a combustion sensing element using this method.

The zirconia green sheet 11 used in the present invention is made by diluting zirconia powder with a known organic solvent and diluting it with a known organic solvent. In addition, it is made into a slurry, made into a sheet by a known method (e.g. extrusion molding method, doctor blade method, etc.), and then heat is removed to volatilize the organic solvent. The platinum paste used can be a mixed paste of palladium, rhodium, etc. in addition to platinum, and the same performance can be obtained by a forming method such as screen printing or roller transfer.

Effects of the Invention With the present invention configured as described above, a zirconia tube body of arbitrary dimensions can be obtained by cutting the zirconia green sheet, and inner electrodes and outer electrodes can be easily formed according to these dimensions. Moreover, electrodes can be formed only in the necessary locations as an electrode pattern, and a combustion sensing element having constant and uniform inner and outer electrodes can be obtained using the minimum necessary electrode material.

Therefore, it has excellent productivity, excellent reliability, low cost, and extremely practical use.

[Brief explanation of the drawing]

1 and 2 show a conventional combustion detection element for explaining the present invention, FIG. 1 is a perspective view, FIG. 2 is a sectional view,
3, 4, and 6 are perspective views showing states during the manufacturing process of a combustion sensing element constructed according to an embodiment of the present invention, FIG. 6 is a perspective view of a completed combustion sensing element, and FIG. The figure is a sectional view of the same. 11...zirconia green sheet, 12...
... Electrode pattern, 13 ... Electrode pattern,
21... Siliconia tube body, 22... Inner surface electrode, 23... Outer surface electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure Tail 3

Claims (1)

[Claims] (1) A combustion detection element characterized by using a zirconia tubular body composed of a cylindrical zirconia green sheet that has an inner electrode and an outer electrode on a part of its surface. (→ Zirconia Green A method for manufacturing a combustion sensing element, comprising forming an electrode pattern on a part of the sheet surface, processing the zirconia green sheets into a cylindrical shape so that one end is overlapped, and firing the zirconia green sheets to form a zirconia tube.