JPS63149555A - Assembling structure of detection element - Google Patents

Abstract

PURPOSE:To fix a detection element to a flange part in a high airtightness holding state, by setting the ratio of the coefficients of thermal expansion of the detection element, glass and the flange part to a range of 1:0.5-1:1-2. CONSTITUTION:Glass 20a is allowed to fill the gap 21 between the detection element 10 inserted in a flange part 20 and the flange part 20 to b melted under heating and subsequently cooled and solidified to fix the element 10 to the flange part 20. Since the ratio of the coefficient of thermal expansion of the element 10 and that of the flange part 20 is 1:1-2, the gap 21 between the flange part 20 and the element 10 becomes narrow as the glass 20a is lowered in its temp. and solidified. Therefore, the glass 20a allowed to fill the gap 21 receives stress from the flange part 20 and the element 20 with the advance of solidification, and the flange part 20 and the element 10 are closely adhered so as to make the gap 21 sufficiently airtight. Further, since the ratio of the coefficient of thermal expansion of the element 10 and that of the glass 20a is 1:0.5-1, even when the gap 21 becomes narrow and the stress from the flange part 20 or element 10 increases, stress is prevented from becoming excessive by the shrinkage of the glass 20a and no gap is generated by the excessive shrinkage of the glass 20a and the element 10 is fixed to the flange part 20 in a high airtightness holding state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a structure for assembling a detection element to a collar.

[Prior Art] In recent years, various sensors have been used for the purposes of pollution prevention, energy conservation, detailed process management, and the like.

One such sensor is one in which a detection element made of a cylindrical or plate-shaped ceramic is attached to a cylindrical metal shell via a cylindrical flange.

Such a sensor first inserts a detection element into the flange, and then
Next, the gap between the flange and the detection element is filled with glass, cement, etc. for fixation and airtightness, then the detection element fixed to the flange is inserted into the metal shell, and finally the metal shell is partially sealed. The sensing element is assembled by tightening the flange by crimping from the outside of the metal shell while applying resistance heating.

[Problems to be Solved by the Invention] However, in such a detection element assembly structure, glass is used to fix the detection element;
When the molten glass cools and solidifies, gaps may be created, which causes problems with airtightness. If this airtightness is not maintained, the measured gas will leak to the atmosphere and measurements using the difference in gas partial pressure between the measured gas side and the atmosphere will become inaccurate. There was a problem in that the work process was complicated because the airtightness had to be improved by using materials.

The present invention aims to solve the above problems.

[Means for Solving the Problems] The present invention employs the following configuration as a means for solving the above problems.

That is, the present invention provides a detection element in which a detection element for detecting the state of the surrounding environment is inserted into a through hole of a cylindrical flange, and glass is filled and fixed in the gap between the detection element and the flange. In the assembly structure, the ratio of the thermal expansion coefficients of the detection element, the glass, and the flange is 1:
The gist of the present invention is a detection element assembly structure characterized by a ratio of 0.5 to 1:1 to 2.

Here, as the glass, for example, lead glass or boric acid glass is used. Further, the detection element is preferably cylindrical, and the flange is suitably made of ceramic or metal (stainless steel, etc.).

Further, the glass may contain additives (alumina, magnesia, etc.) within a range that does not change the ratio of the thermal expansion coefficients.

The detection element may be a solid ionic conductor such as Zr0z or T! (A gas detection element using a material whose resistivity changes depending on the surrounding atmosphere like h) or a temperature detection element such as a thermistor can be used.

[Operation] The detection element is fixed to the flange by filling the gap between the cylindrical flange and the detection element inserted into the flange with glass, heating it to melt it, and then cooling and solidifying it. be done. Since the ratio of the thermal expansion coefficients of the sensing element and the flange is in the range of 1:1 to 2, the temperature of the glass decreases and solidifies, and the gap between the flange and the sensing element narrows. Therefore, the glass filled in this gap solidifies and receives stress from the flange and the detection element, and comes into close contact with the flange and the detection element so that the gap is sufficiently airtight.

Roughly speaking, the ratio of the thermal expansion coefficients of the detection element and glass is 1:0.
．． Since the value is in the range of 5 to 1, even if the above-mentioned gap becomes narrower and the stress from the flange and the detection element increases, the stress will be prevented from becoming excessive due to shrinkage of the glass itself, and the glass will not break. No cracks will occur. Moreover, since it does not contract too much and create a gap, the detection element can be fixed to the flange while maintaining high airtightness.

[Example] A first example of the present invention will be described with reference to the drawings. It should be noted that the scales of each figure are different for explanation purposes.

In this embodiment, the present invention is applied to an oxygen sensor S1 using a columnar oxygen detection element 10, and FIG. 1 is a partially cutaway front view of the oxygen sensor S1, and FIG. 2 is a main part thereof. FIG.

The metal shell 12 made of stainless steel (StJS430) is formed into a cylindrical shape in order to fix the oxygen detection element 10 and to attach this sensor to an internal combustion engine. This main metal fitting 1
A threaded portion 12a for attaching an internal combustion engine is carved on the outer periphery of 2. The configuration of the oxygen detection element 10 will be described later.

The protector 14 is attached to the tip of the metal shell 12 on the internal combustion engine side, and protects the oxygen detection element 10. The tube 16 is attached to the main metal fitting 12, and the outer tube 18 is attached to the tube 16 to connect the oxygen detection element 10 and its pin terminal 10.
a, protect 10b.

To assemble the oxygen detection element 10 to the metal shell 12, first insert the oxygen detection element 10 into the cylindrical ceramic (AQzOi, ZrO2, etc.) flange 20, so that the flange 20 and the oxygen detection element 10 are formed. Glass 20a (
Fill with lead glass, oxalic acid glass, etc.) and heat to melt. Next, the glass 20a is cooled and solidified to close the gap 21 and make it airtight, and the oxygen detection element 1 is attached to the flange 20.
Fix 0 (see Figure 2). Next, the gap 22 between the flange 20 and the metal shell 12 is filled with a filler 23 such as talc,
stainless! A fixing ring 24 made of steel (SUS403) is inserted from above, and the collar portion 20 is fixed by crimping from the outside of the metal shell 12 by resistance heating.

The outer diameter of the detection element is 3.degree. 3 mm, the total length of the flange is 27 mm, the inner diameter of the portion of the flange that contacts the glass is 4.7 mm, and the outer diameter is 7.4 mm. Regarding the relationship of thermal expansion coefficients among these members, members are used in which the ratio of the thermal expansion coefficients of the detection element, the glass, and the flange is in the range of 1:0.5 to 1:1 to 2. The filler 23 is ceramic powder such as talc.

Ceramic fibers such as glass fibers, heat-resistant metal fibers such as stainless steel, etc. can be used.

The oxygen detection element 10 has two measurement bottle terminals 10a, 10.
It has a total of four pin terminals: b and two heater pin terminals (not shown). Pin terminal 10 of this oxygen detection element 10
a and 10b are electrode terminals 308 to 30 of the oxygen detection element 10
d (see Figure 4) and is connected by a brazed C-pull. The measurement pin terminals 10a and 10b and the heater pin terminals are crimped and connected to the corresponding lead wires 328 to 32d, respectively. This connection portion is insulated and protected by a sealing material 34 made of silicone rubber.

The configuration of the oxygen detection element 10 will be explained using the perspective view of FIG. 3 and the exploded perspective view of FIG. 4.

This oxygen detection element 10 includes a hollow zirconia core material 102 to which a zirconia bottom 101 is bonded, and an inner electrode 1
03. It is covered with a solid electrolyte layer 106 provided with an outer electrode 104 and a heating element 105. This inner electrode 1
03 and the outer electrode 104 are opposed to each other with a solid electrolyte layer 106 in between.

Furthermore, the inner electrode 103 is connected to the inner electrode terminal 30a by through-hole processing. Further, the outer electrode 104 is connected to the outer electrode terminal 30b, the heating element 105 is connected to the heating element terminal 30c,
30d.

Furthermore, the inner electrode terminal 30a and the outer electrode terminal 30b are connected to the measurement bottle terminals 10a, 10b, and the heating element terminals 30c, 30.
d are connected to heater pin terminals by silver soldering. Note that the heating element 105 cannot be seen in FIG. 3 because it is covered with a heating element protective layer. Furthermore, core material 10
2 is provided with two holes 110 for guiding the atmosphere to the inner electrode 103.

The core material 102 used in this oxygen detection element 10 has an outer diameter of 2
．． It has a hollow cylindrical shape with a diameter of 5 mm, an inner diameter of 1.5 mm, and a length of 5 Q mm. This core material 102 can be easily formed by extrusion molding.

The solid electrolyte layer 106 is obtained by mixing Y2O3-ZrO2 solid solution raw material powder with a commonly used binder and cutting the green sheet into 17 mm x 37 mm. This green sheet is provided with an electrode pattern as shown in FIG. 3 by thick film printing. Electrode 103.1
04, heating element 105 and terminals 30a to 30d are Y20
It consists of platinum containing 15 wt% of 3-Zroz solid solution. Moreover, the heating element 105, the solid electrolyte layer 106 and/or the core material 1
02, an insulating layer made of alumina or the like is provided, although not shown.

A green sheet, which will become the solid electrolyte layer 106 on which the bottom 101 and the electrode pattern described above are formed, is wrapped around the core material 102 [
Crimp and fix and bake in the atmosphere.

Furthermore, measurement pin terminals 10 are attached to each of the above terminals 308 to 30d.
A, 10b and the heater pin terminal are connected as described above, and the flange 20 is fixed at a position 4 Qmm from the end 120 of the core material 102 using the glass 20a as shown in FIG. obtain. Since this core material 102 is hollow, its heat capacity M is small, and the heating element 105 can easily bring the oxygen detection element 10 to a temperature suitable for measurement.

Moreover, the oxygen sensor S1 assembled with the oxygen detection element 10 is as follows:
Since the oxygen detection element 10 is rod-shaped, there is little directionality.

Table 1 shows the results of airtightness experiments conducted using the oxygen sensor S1. Table 1 shows the oxygen detection element 10 of the oxygen sensor S1 used in the experiment. Glass 20a and flange 20
The thermal expansion coefficient of Examples (No. 1 to 4) and Comparative Example (No.
5 to 6), and the evaluation of airtightness is described as either good (OK) or unsuitable (NG).

Table 1 Next, Table 2 shows the ratios of thermal expansion coefficients between the oxygen detection element 10 and the glass 20a, and between the oxygen detection element 10 and the flange 20.

Table 2 As is clear from the results listed in Tables 1 and 2, the present oxygen sensor S1 using the above-mentioned detection element assembly structure has an oxygen detection element 10. Glass 20a and flange 20
The ratio of thermal expansion coefficients is 〇.

The ratio is in the range of 5-1:1-2. Therefore, in a high temperature state where the glass 20a is molten, the gap 21 formed by the flange 20 and the oxygen detection element 10 widens because the flange has a large coefficient of thermal expansion, and then the temperature decreases and the glass 20a expands.
As a solidifies, the gap narrows. As a result, the glass 20a receives stress from both sides, and can be brought into close contact with the flange portion 20 and the oxygen detection element 10 to achieve a sufficient airtight seal. Further, the glass 20a also contracts upon cooling, but as long as the ratio is within the above range, the glass 20a will not crack or crack due to stress, and will not contract too much and create gaps.

Therefore, the oxygen detection element 10 can be fixed to the flange 20 using only the glass 20a without using any other filler, and airtightness can also be achieved within -1 minute. This makes the working process very easy and simple.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the present invention is applied to an oxygen sensor S2 using a columnar oxygen detection element 200, and FIG. 5 is a partially cutaway front view of the oxygen sensor S2.

The main difference between this oxygen sensor S2 and the first embodiment is that the flange 210 into which the oxygen detection element 200 is inserted is made of a rigid, heat-resistant metal, such as stainless steel (SUS3108, etc.). It is. This oxygen sensor S2 includes a metal shell 212, a protector 214, cylinders 216a, 2
Electrode terminals 230a, 230 of the 16BL element detection element 200
measurement pin terminal 20 connected to b by brazing
0a, heater pin terminal (not shown), pin terminal 200a
The lead wires 232a to 232d are crimped and connected to the lead wires 232a to 232d, and a sealing material 234 made of silicone rubber is provided to insulate and protect the connected portions. In addition, the oxygen detection element 200 and the flange 210
is fixed using glass 210a to maintain airtightness.

This sensor S2 is assembled by inserting the flange portion 210 of the oxygen detection element 200 from the threaded portion 212a side of the metal shell 212. In this sensor S2, since the flange 210 is made of metal, it can be crimped directly from the outside of the metal shell 212 by resistance heating, and there is no need for fillers or fixing rings, which has the advantage of simplifying the work process. .

[Effects of the Invention] As described above, in the present invention, since the ratio of the thermal expansion coefficients of the detection element, the glass, and the flange is in the range of 1:0.5 to 1:1 to 2, the flange and the detection element can be detected by the glass. In addition to fixing the element, it is possible to maintain sufficient airtightness. Therefore, since no other filler is required, the working process becomes very easy and simple.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a first embodiment of the present invention, FIG. 2 is a partially cutaway perspective view showing the main parts thereof, and FIG. 3 is a perspective view of an oxygen detection element 10 used therein. FIG. 4 is an exploded perspective view thereof, and FIG. 5 is a partially cutaway front view of the second embodiment of the present invention. Sl, S2... Oxygen sensor 10.200... Oxygen detection element 12.212... Metal shell 20.210... Flange 2Qa, 210a... Glass

Claims (1)

[Claims] 1. A detection device in which a detection element for detecting the state of the surrounding environment is inserted into a through hole of a cylindrical flange, and a glass is filled and fixed in the gap between the detection element and the flange. In the element assembly structure, the ratio of the thermal expansion coefficients of the detection element, glass, and flange is 1:
A detection element assembly structure characterized in that the ratio is in the range of 0.5 to 1:1 to 2. 2. The detection element assembly structure according to claim 1, wherein the detection element has a cylindrical shape. 3. The detection element assembly structure according to claim 1 or 2, wherein the flange is made of ceramic or metal.