JPH0599891A - Limiting-current type oxygen sensor - Google Patents

Abstract

PURPOSE:To improve productivity of a limiting-current type oxygen sensor for measuring oxygen concentration in an atmosphere. CONSTITUTION:An oxygen ion conductive solid electrolyte plate 1 with a spiral spacer 3 formed on a side and electrode films 2a,2b formed on both sides is laminated in a recess formed by laminating a holder 7 on an insulator 10, and a seal plate 4 with a heating part 6 is further laminated. Both plates can be fixed to each other without shift, alignment is easy and productivity can be improved due to reduction in a process and time. On the other hand, electric conductivity between the electrode films 2a,2b together with the heating part 6 and lead films 9a,9b,9c,9d formed on the insulator 10 is coupled via conductive adhesive 11a,11b,11c,11d, thereby simply allowing electric conductivity and fixing and improving productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a limiting current type oxygen sensor for measuring oxygen concentration in an atmosphere.

[0002]

2. Description of the Related Art Conventionally, various structures of a limiting current type oxygen sensor have been devised. An example of a conventional limiting current type oxygen sensor is shown in FIG. Reference numeral 1 is a solid electrolyte plate having oxygen ion conductivity, and electrode films 2a and 2b (not shown) on both sides.
Are formed. A spiral spacer 3 is arranged on one surface of the solid electrolyte plate 1 so as to surround the electrode film 2a and has a start end and an end spaced from each other, and a seal plate 4 is arranged above the spiral spacer 3. The oxygen diffusion passage 5 is formed by a spiral space surrounded by the partition walls of the spiral spacer 3 facing each other, the solid electrolyte plate 1 and the seal plate 4, and oxygen diffuses into the electrode film 2 a via the oxygen diffusion passage 5. To do. A heating unit 6 is formed on the seal plate 4 to heat the solid electrolyte plate 1 to improve the conduction of oxygen ions.

For electrical connection of these limiting current type oxygen sensors, a lead wire (not shown) of an ultrafine platinum wire is applied to the electrode films 2a, 2b and the heating portion 6 and fixed with a conductive adhesive, and further mounted. The platinum lead wire is applied to the nickel wire terminal (not shown) and welded. In this electrical connection method, (1) the platinum lead wire cannot be directly welded to the electrode film and the heating portion (because the platinum lead wire can be removed even if it is welded), (2) the nickel wire terminal of the mounting body cannot be directly fixed. It is a method that cannot be done (because it is difficult to achieve both fixing and maintaining electrical continuity), and (3) soldering cannot be performed because it is heated to around 400 ° C.

[0004]

However, in the above-mentioned structure, the electrode film and the heating part are electrically connected by a step of applying a lead wire made of an extra fine platinum wire to the electrode with a conductive adhesive, and a nickel wire. Since the above-mentioned platinum lead wire is applied and welded to the terminal, the lead wire connection becomes complicated, and many steps and time are required for this electrical connection, and there is a problem that productivity is not improved.

In addition, the positional deviation between the solid electrolyte plate and the seal plate in the stack is caused by the formation of oxygen diffusion passages in the spiral-shaped space surrounded by the partition walls facing each other of the spiral spacer, the solid electrolyte plate and the seal plate. In view of the configuration, the critical current characteristics are fatally affected and must be avoided as much as possible. Therefore, there is a problem in that this alignment requires many steps and time, and productivity is not improved. The present invention solves the conventional problems, and an object of the present invention is to provide a sensor structure that is excellent in mass productivity and easy to manufacture.

[0006]

In order to solve the above problems, a limiting current type oxygen sensor of the present invention is an insulator having a through hole and a lead wire film formed on the surface thereof, and the periphery of the through hole of the insulator. A holding body for laminating in a part to form a concave recess, and a spiral spacer formed on both surfaces with a pair of electrode films formed and surrounding the electrode film so that the start end and the end are spaced from each other on one side. It is composed of the formed oxygen ion conductive solid electrolyte plate and a seal plate having a heating portion formed on the surface thereof. Then, the holding body is laminated on the insulator to form a concave recess, the solid electrolyte plate is laminated on the concave recess, and the sealing plate is further laminated on the solid electrolyte plate to form the spiral spacer. An oxygen diffusion passage is formed in a spiral space surrounded by the partition walls facing each other and the seal plate, and the electrode film and the heating portion are connected to the lead wire film via a conductive adhesive.

As another invention for solving the above-mentioned problems, a limiting current type oxygen sensor of the present invention has a seal plate having a lead wire film and a heating portion formed on the surface thereof, and a concave recess formed by laminating on the seal plate. And an ion-ion-conducting solid electrolyte plate on one side of which a spiral spacer is formed on both sides of which a holding body and a pair of electrode films are formed and which are arranged so as to surround the electrode film and have a starting end and a terminating end spaced from each other. Composed of and. Then, the holder is laminated on the seal plate to form a concave recess, and the solid electrolyte plate is laminated on the concave recess to form a spiral type surrounded by the opposing partition walls of the spiral spacer and the seal plate. An oxygen diffusion passage is formed in the space, and the electrode film and the heating part are connected to the lead wire film via a conductive adhesive.

[0008]

With the above structure, the solid electrolyte plate is stacked in the concave recess formed by stacking the holder on the insulator, and the seal plate is stacked on the insulator. It is fixed without shifting. Therefore, the alignment can be easily performed, and the productivity is improved by shortening the process and time. On the other hand, since the electrical conduction between the electrode film and the heating portion and the lead wire film of the insulator is performed via the conductive adhesive, the electrical conduction and fixing can be easily performed, and the process and the time can be shortened to improve the productivity. improves.

In addition, in other configurations than the above, the solid electrolyte plate is stacked in the concave recess formed by stacking the holder on the seal plate, so that the two are correctly aligned, and both are It is fixed without shifting and can be easily aligned. Moreover, since electrical conduction between the electrode film and heating part and the lead wire film of the insulator is also performed via the conductive adhesive, electrical conduction and fixing can be easily performed, and productivity is improved by shortening the process and time. To do.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an exploded view of a limiting current type oxygen sensor which is another embodiment of the present invention. The limiting current type oxygen sensor includes a holder 7 and an insulator 10 having a through hole 8 and four lead wire films 9a, 9b, 9c and 9d formed on the surface thereof.
And an oxygen ion conductive solid electrolyte plate 1 having opposite electrode films 2a and 2b (not shown) formed on both sides thereof, and the electrode film 2a formed on one side of the solid electrolyte plate 1 is surrounded by a starting end and a terminating end. The spiral spacers 3 are arranged so as to be spaced from each other, the sealing plate 4 having the heating portion 6 formed on the surface thereof, and the four conductive adhesives 11a, 11b, 11c, 11d.

The assembly is carried out in the following procedure. First, the holder 7 is laminated around the through hole 8 of the insulator 10 to form a concave recess. The through hole 8 is a portion corresponding to the electrode film 2b and is utilized for oxygen transfer. The lead wire film 9b has an extended portion 9b in the concave portion.
The conductive adhesive 11b is applied to -1. The conductive adhesive 11b is used for the anode-side electrode 2 of the solid electrolyte plate 1.
It is used for electrical connection and coupling between b (not shown) and the lead wire film 9b. After that, in the concave recess 7, the spiral spacer 3
The solid electrolyte plate 1 formed in advance is laminated, and the seal plate 4 is further laminated thereon. Then, the electrode film 2a and the heating portion 6 are electrically connected by coating the lead wire films 9a, 9c, 9d and the conductive adhesives 11a, 11c, 11d. Finally, the sensor is fired to form the spiral spacer 3
Is melted to form a spiral space (utilized as an oxygen diffusion passage) surrounded by the partition walls of the spiral spacer 3 facing each other, the solid electrolyte plate 1 and the seal plate 4. Also, the electrode film 2
a, 2b (not shown) and the heating part 6 are connected to the lead wire film 9
a, 9b, 9c, 9d and conductive adhesives 11a, 11b,
11c and 11d are joined by melting, and the insulator 10 and the holding body 7 are also joined by melting the bonding agent previously applied between them.

FIG. 2 is an assembly diagram of the limiting current type oxygen sensor of FIG. The solid electrolyte plate 1 and the seal plate 4 are provided in the concave recess portion formed by the holder 7 laminated on the insulator 10.
It is fixed. Further, the lead wire films 9a, 9
b, 9c and 9d are conductive adhesives 11a, 11b and 11
It is connected to the electrode film and the heating unit 6 via c and 11d.

FIG. 3 is an exploded view of a limiting current type oxygen sensor according to another embodiment of the present invention. The limiting current type oxygen sensor has a holder 7 and four lead film 9a, 9b,
9 c, 9 d and a seal plate 4 on which a heating unit 6 is formed, an oxygen ion conductive solid electrolyte plate 1 having opposite electrode films 2 a (not shown) and 2 b formed on both sides, and a solid electrolyte plate 1 on one side. Spiral spacers 3 that are formed and are arranged so as to surround the electrode film 2a and have a starting end and a terminating end spaced from each other;
It is composed of two conductive adhesives 11a, 11b, 11c (not shown) and 11d (not shown).

Assembly is performed in the following procedure. First, the heating portion 6 formed on the seal plate 4 is replaced with the conductive adhesive 11c, 11
The application of d makes the lead wires 9c and 9d conductive. Next, the holder 7 is laminated on the seal plate 4 to form a concave recess. Then, the conductive adhesive 11a is applied to the extended portion 9a-1 of the lead wire film 9a which is present in the concave portion. The conductive adhesive 11a is used for electrical connection and connection between the anode side electrode 2a (not shown) of the solid electrolyte plate 1 and the lead wire film 9a. After that, the solid electrolyte plate 1 on which the spiral spacer 3 is preliminarily formed is laminated in the concave recess. Then, the electrode film 2b is connected to the lead wire film 9b and the conductive adhesive 11
Electrical conductivity is achieved by applying b. Finally, the sensor is fired to melt the spiral spacer 3 to form a spiral space (utilized as an oxygen diffusion passage) surrounded by the opposing partition walls of the spiral spacer 3, the solid electrolyte plate 1 and the seal plate 4. To be done. In addition, the electrode films 2a (not shown) and 2b and the heating portion 6 are joined by melting the lead wire films 9a, 9b, 9c and 9d and the conductive adhesives 11a, 11b, 11c and 11d, and the sealing plate 4 The holding body 7 and the holding body 7 are bonded by melting the bonding agent previously applied between them.

FIG. 4 is an assembly diagram of the limiting current type oxygen sensor of FIG. The solid electrolyte plate 1 is fixed to the concave portion formed by the holder 7 laminated on the seal plate 4 in a lump. In addition, the lead wire films 9a, 9b, 9c, 9
d is connected to the electrode film and the heating unit 6 via the conductive adhesives 11a, 11b, 11c and 11d. The heating part 6 may be formed on the back side of the seal plate 4 as a method other than that shown in FIG.

In the embodiment of FIGS. 1-2, insulator 10
An alumina plate having a size of 15 × 70 × 1 mm was used. A through hole 8 (diameter 5 mm) is formed in advance in this insulator 10, and platinum lead wire films 9a, 9b, 9c, and
9d was formed using thick film printing. Then, the insulator 10
The holder 7 is laminated around the through hole 8 of the concave hole (11).
X 11 x depth 1.0 mm) was formed. Next, in the recess 9 of the insulator 10, particularly in the portion 9b-1 in which the lead wire film is extended,
A conductive adhesive 11b made of gold paste, which is electrically conductive with the lead wire film 9b, was applied. The conductive adhesive 11b is used to bond the anode side electrode 2b of the solid electrolyte body and the lead wire film 9b. After that, the solid electrolyte plate 1 (10 × 10 × 0.4) made of zirconia was formed in the concave depression 7.
5mm) Furthermore, forsterite seal plate 4 (10 x
10 × 0.3 mm) was laminated. And the platinum electrode film 2
a and the heating part 6 made of a platinum heater are connected to lead wire films 9a, 9
c, 9d and conductive paste 11a, 11 made of gold paste
Electrical conductivity is obtained by coating c and 11d. Finally, the sensor is fired to melt the glass spiral spacer 3 (thickness 40 μm), and the spiral space surrounded by the partition walls of the spiral spacer 3 facing each other, the solid electrolyte plate 1 and the seal plate 4 (oxygen It is used as a diffusion passage). on the other hand,
The electrode films 2a and 2b and the heating unit 6 are connected to the lead wire films 9a and 9a.
9b, 9c, 9d and conductive adhesive 11a, 11b, 11
It is joined by melting of c and 11d. As a result, the positioning of the solid electrolyte plate and the seal plate and the electrical conduction of the electrode film and the heating part can be simplified, and the productivity is improved.

As the solid electrolyte plate 1, ZrO ₂ .Y
₂ O ₃ (Y ₂ O ₃ 8 mol% added), electrode films 2a, 2b
Platinum, spiral spacer 3 made of glass (coefficient of thermal expansion is approximately the same as ZrO ₂ .Y ₂ O _3, and contains a small amount of heat-resistant particles having a predetermined particle size), seal plate 4 is forsterite, and heating unit 6 is made of platinum. A heater was used. The manufacturing method will be described. First, the electrode films 2a and 2b are attached to the solid electrolyte plate 1
In addition, the spiral spacer 3 was further formed on the solid electrolyte plate 1 by using the thick film printing technique and the firing technique.
On the other hand, the heating portion 6 on the sealing plate 4 was formed by using the thick film printing technique and the firing technique. In addition, the solid electrolyte plate 1
It is designed that the upper spiral spacer 3 and the seal plate 4 are laminated and heated and melted to form an oxygen diffusion passage.

The operation will be described. In the above configuration, a predetermined electric power is applied to the heating unit 6 via the lead wire films 9c and 9d to heat the solid electrolyte plate 1 to a predetermined temperature via the heating unit 6. On the other hand, similarly, through the lead wires 9a and 9b, the solid electrolyte plate 1 (in this case, the electrode films 2 formed on both surfaces)
A predetermined voltage is also applied to a, 2b). Then, oxygen in the air flows in via the oxygen diffusion passage 5, and further oxygen ions flow in the solid electrolyte plate 1 from the cathode side electrode film 2a toward the anode electrode film 2b. Oxygen moves through the solid electrolyte plate 1 by this oxygen pump action,
Since the oxygen diffusion passage 5 restricts the inflow of oxygen molecules, a saturation current (referred to as a limiting current) depending on the oxygen concentration is generated.

This sensor is packaged with a heat insulating material, a lead wire film is soldered with a copper wire to form a mounting structure, and 2.7 W is applied to the heating portion.
When the voltage of 1.4V is applied to the electrode film by maintaining the temperature at about 450 ° C by applying the electric power of 190μA (oxygen 20%
A limiting current of (middle) was obtained. The limiting current value was approximately proportional to the oxygen concentration.

The embodiment of FIGS. 3 to 4 is also substantially the same as the above, and a forsterite plate having a size of 15 × 70 × 0.35 mm is used as the seal plate 4, and the holding bodies 7 are laminated to form a concave depression (11 ×).
11 x depth 0.5 mm) was formed. Then, the lead wire film 9
Conductive adhesive 1 for making the extended portion 9a-1 of a electrically conductive with the anode side electrode 2a of the solid electrolyte plate 1
1a was applied. The heating unit 6 was previously electrically connected to the lead wire films 9c and 9d using a conductive adhesive. After that, a solid electrolyte plate 1 (10 × 10 × 0.45 mm) made of zirconia is laminated on the concave recess via a spiral spacer 3, and the electrode film 2b is connected to the lead wire film 9b and the conductive adhesive 11b.
Was applied to make electrical conduction. Finally, the sensor is fired to melt the spiral spacer 3 to form a spiral space (utilized as an oxygen diffusion passage) surrounded by the partition walls of the spiral spacer 3 facing each other, the solid electrolyte plate 1 and the seal plate 4. did. In addition, the electrode films 2a and 2b and the heating unit 6 include the lead wire films 9a, 9b, 9c and 9d and the conductive adhesives 11a and 1a.
Bonded by melting of 1b, 11c and 11d. As a result, sensor assembly is easy and productivity is improved.

This sensor is packaged with a heat insulating material, a lead wire film is soldered with a copper wire to form a mounting structure, and 2.8 W is applied to the heating portion.
When the voltage of 1.4 V is applied to the electrode film by maintaining the temperature at about 450 ° C by applying the power of 160 μA (oxygen 20%
A limiting current of (middle) was obtained. The limiting current value was approximately proportional to the oxygen concentration.

[0023]

As described above, according to the limiting current type oxygen sensor of the present invention, the following effects can be obtained. (1) When the solid electrolyte plate is stacked (and the seal plate is further stacked) in the concave recess formed by stacking the holder on the insulator (or the seal plate), the alignment is correctly performed, and the two are displaced. Fixed without. Therefore, the alignment can be easily performed, and the productivity is improved by shortening the process and time. (2) Since the electrical conduction between the conductive portion of the electrode film and the heating portion and the lead wire membrane of the insulator is coupled via the conductive adhesive, the electrical conduction and fixing can be easily performed and the productivity is improved. ..

[Brief description of drawings]

FIG. 1 is an exploded view of a limiting current type oxygen sensor which is an embodiment of the present invention.

FIG. 2 is an assembly diagram of FIG.

FIG. 3 is an exploded view of a limiting current type oxygen sensor which is another embodiment of the present invention.

FIG. 4 is an assembly diagram of FIG.

FIG. 5 is a partially cutaway perspective view of a conventional limiting current type oxygen sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oxygen ion conductive solid electrolyte plate 2a, 2b Electrode film 3 Spiral type spacer 4 Seal plate 5 Oxygen diffusion passage 6 Heating part 7 Holding body 8 Through holes 9a, 9b, 9c, 9d Lead wire membrane 10 Insulators 11a, 11b, 11c, 11d conductive adhesive

Claims (2)

[Claims] 1. An electrode film forming a pair, an insulator having a through hole and having a lead wire film formed on the surface thereof, a holder for forming a concave recess by laminating the insulating member on a peripheral portion of the through hole. And an oxygen ion conductive solid electrolyte plate on one side of which a spiral spacer is formed on both sides of the electrode film so as to surround the electrode film so that the start end and the end are spaced from each other, and a seal plate on which a heating portion is formed on the surface. And a holder is laminated on the insulator to form a concave recess, the solid electrolyte plate is laminated on the concave recess, and the sealing plate is further laminated on the solid electrolyte plate to form the spiral. A limiting current formed by forming an oxygen diffusion passage in a spiral space surrounded by the partition walls facing each other of the mold spacer and the seal plate, and connecting the electrode film and the heating part to the lead wire film via a conductive adhesive. formula Oxygen sensor. 2. A seal plate having a lead wire film and a heating portion formed on the surface thereof, a holder for laminating on the seal plate to form a concave depression, and electrode films to be paired are formed on both surfaces of the seal plate. It is composed of an oxygen ion conductive solid electrolyte plate formed on one side with a spiral spacer arranged so as to surround the membrane so that the start end and the end are spaced from each other, and the holder is laminated on the seal plate to form a concave recess. And forming the oxygen diffusion passage in a spiral space surrounded by the partition walls facing each other of the spiral spacer and the seal plate by stacking the solid electrolyte plate in the concave recess, and forming the electrode film and the heating unit. A limiting current type oxygen sensor in which the lead wire film is bonded to the lead wire film via a conductive adhesive.