JPS613053A - Detection substrate for oxygen sensor - Google Patents

Abstract

PURPOSE:To control the detected temperature with a simple construction of an oxygen sensor, by providing a reference electrode on the top of a planar piece of solid electrolyte and a measuring electrode on the undersurface thereof to form a detector section, which is provided with a heating resistor each on the top and the undersurface thereof. CONSTITUTION:A reference electrode 11 is provided on the top of a planar piece 9 of solid electrolyte, a conductive part 18 connected thereto and reference gas paths 17 and 26 for air or the like is formed. A measuring plate 12 is provided on the undersurface of the solid electrolyte 9, a conductive part 20 connected thereto and a measuring gas path is formed through a cover coat 30. Heating resistors are provided in the perimeter of the upper path 17 of the reference electrode 20 and in the perimeter of the lower path 4 of the measuring electrode 12 respectively. Then, a reference gas is brought into contact with the reference electrode 11 from the path 17 while a measuring gas is brought into contact with the measuring electrode 12 from the path 4 to heat the solid electrolyet 9 evenly from above the below thereby detecting oxygen. Thus, as sensor members are laminated and heated from above and below with the heating resistors, the oxygen sensor is very simple in the construction and can detect oxygen without being affected by ambient temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection substrate for an oxygen sensor using a solid electrolyte such as zirconium oxide having oxygen ion conductivity.

<Prior art> Using a tiJ solid electrolyte, a reference gas such as air with a known oxygen partial pressure is brought into contact with the upper surface, a measuring gas with an unknown oxygen partial pressure is brought into contact with the lower surface, and each surface is An electromotive force is generated by the difference in oxygen partial pressure between the reference electrode and the measurement electrode that are in contact with the
Oxygen sensors are known in which the oxygen partial pressure of the measurement gas is determined from the well-known Nernst equation by measuring such electromotive force.

Such an oxygen sensor is disclosed in Japanese Patent Publication No. 5B-7588, in which a solid electrolyte is formed into a tube with one end closed, a reference gas is supplied into the tube, and the outer peripheral surface of the tube is exposed to the measurement gas. Normal. However, it is difficult and expensive to form a solid electrolyte into a tubular shape.

Therefore, in order to facilitate the molding of the solid electrolyte, the solid electrolyte is molded into a plate shape, and a reference electrode and a measurement electrode are placed on the hF surface of the sensing portion of the root, as disclosed in Japanese Patent Application Laid-Open No. 125448/1982. , and the conductive path is arranged by pressure bonding or vapor deposition, and the conductive path of the two poles is provided continuously to the signal output port at the end of the plate, and the reference gas and measurement gas are brought into contact with the lower surface of L of the detection part. A detection substrate has been proposed.

However, in such a configuration, the conductive path is connected to the solid electrolyte l F
Since it is arranged directly on the surface, it is long in the conductive direction, and a large amount of solid electrolyte is used, making the detection element expensive. In addition, when forming electrodes and conductive paths on the lower surface of the L of the solid electrolyte by means such as vapor deposition in order to eliminate noise caused by the conductive paths, an insulating plate or the like is interposed to insulate the solid electrolyte and the conductive paths. The necessity arises, the installation is troublesome, and the structure is complicated.

Further, the optimum operating temperature of the fixed electrolyte is 300° C. or higher, and therefore, it is necessary to perform temperature compensation in order to operate the solid electrolyte well at low temperatures. By the way, in order to perform temperature compensation with the conventional detection board, it is necessary to interpose an insulating plate on the electrode and then separately provide a heater.

Furthermore, since the heating is applied only from one side of the solid electrolyte, the temperature distribution of the electrolyte is not uniform, and the temperature compensation is incomplete.

<Objective of the Invention> The object of the present invention is to provide a detection substrate that can be easily manufactured by laminating plate materials, uses as little solid electrolyte as possible, and can provide good temperature compensation for the solid electrolyte. It is something.

<Structure of the Invention> A first heating member consisting of a heating resistor located around the hole and a power supply path for the resistor is disposed on one surface of an insulator in which a hole is formed, and the heating member from below with a protective plate, and a small plate-like piece made of solid electrolyte is placed on the top surface of the insulator.
- A detection element plate is placed on the ri, in which a reference electrode is formed on the F side, a measuring rod is formed on the F side exposed to the measurement gas, and the measuring electrode is electrically connected to the connection end formed on the upper surface side, and Protective plates are arranged on two sides of the insulator adjacent to the detection element plate.

A power distribution board is disposed so as to cover the detection element plate and the protection plate from the upper surface, and the power distribution board has a hole opening in the reference electrode, and one end thereof is connected to the reference electrode. A reference side conductive path and a measurement side conductive path whose one end is connected to the connection end of the measurement electrode are provided, and a heating resistor located around the hole of the power distribution board and a heating resistor located around the hole of the power distribution board are provided on the upper surface of the power distribution board. A second heating member consisting of a power supply path is disposed, and the upper surface of the power distribution plate is further covered with an attached body having a flow path communicating with the hole.

<Example> An embodiment of the invention will be described with reference to the accompanying drawings.

1 in the figure is an insulator made of a metal oxide such as gAI03 or a ceramic material such as fermented aluminum, which has a hole 2 formed in its left end, and has a hole 2 formed above and below the hole 2 on its lower surface. A protective plate 3 made of the same material as the insulator 1 and having a corresponding hole 4 of the same shape is joined. A first heating member 5 consisting of a heating resistor 6 formed around the hole 4 and power supply paths 7, 7 of the resistor 6 extending along the longitudinal direction is provided on the upper surface of the hole 4, The protection plate 3 is made a little shorter than the insulator 1, and the power supply path 7.7 is slightly protruded to the left, so that the ends of the power supply paths 7, 7 are inserted from below when the insulator 1 and the protection plate 3 are joined. so that there is no problem with the power supply.

The first heating member 5 may not be provided on the upper surface of the protection plate 3 but may be provided on the lower surface of the insulator l.

9 is a detection element plate, and as shown in FIGS. 2 and 3, a small rectangular plate 10 made of a solid electrolyte such as zirconium Mide
A rectangular reference electrode 11 is placed on the surface of the F exposed to the measurement gas.
The measuring electrodes 12, which are also rectangular, are formed in correspondence with each other on the surface, and the connecting end 1 is connected from the right edge of the reference electrode 11 in the figure.
1a protrudes, and a thin conductive path 13 is further extended from the end of the measurement electrode 12, running along the side edge of the plate-shaped small piece 10, and connected to the measurement side connection provided at the upper end of the plate-shaped small piece 10. Edge 1
It is electrically connected to 2a.

14 is made of an insulating material such as aluminum oxide, which is adjacent to the detection element plate 9 with a minute gap 15 therebetween, has the same width, and forms a rectangular outer shape together with the detection element plate 9 in the adjacent state. It is a protective plate.

The detection element plate 9. A power distribution board 16 made of an insulating material such as aluminum oxide is bonded onto the protection board 14, covering both of them and protruding slightly to the right end. As shown in FIG. 2.4, the power distribution board 16 has the reference electrode 1 on its left end side.
A rectangular hole 17 is formed which coincides with 1 at one end, and a reference side conductive path 18 is formed on the upper surface of the hole 17 extending leftward along the longitudinal direction from the signal extraction section 19 at the right end. The left end extends along the side edge of the hole 17 and connects to the power distribution board 1.
6 and the reference electrode 1 on the 16th side of the distribution board.
1 and the quasi-pole 11
is connected to the signal extraction section 19. Further, on the lower surface of the power distribution board 16, there is a signal output portion 21 at the right end thereof.
A measurement-side conductive path 20 is formed extending to the left along the longitudinal direction from the top, and its left end contacts the connection end 12al, so that the measurement electrode 12 is electrically connected to the signal extraction section 21. .

Further, on the upper surface of the power distribution board 16, a second power supply path 24, 24 is formed, which includes a heating resistor 23 surrounding the hole 17 and a second power supply path 24.
A heating member 22 is provided. …j heating resistor 23
is formed by applying a material such as molybdenum by means such as screen printing.

As you can see, a U-shaped frame piece 25 with an open right end is not mounted on the power distribution board 16, and the empty space 26 in the center thereof is arranged from the hole 177 to the right end. . A horizontally long blocking piece 1≧ω7 is arranged in the middle part of the cavity 26, and the cavity 26 allows the right end inflow 1. + 26 a to the outlet 26 b in a detour to form a flow path that enables flow in the - direction.

A mounting plate 28 that shields the empty space 26 at the upper part is attached to the frame piece 25. Blocking piece? 7. Boarding 4
28 constitute a lid body 29. The outer shape of the lid body 29 is similar to that of the detection element plate 9. It is made to match the outer peripheral shape of the protection plate 14.

Said frame piece 25. Blocking piece 27. The cover plate 28 is made of an insulating material such as oxidized aluminum 1. Moreover, the lid body 29 may be of an integral structure instead of being composed of each component piece.

Furthermore, the second heating member 22 may not be provided on the power distribution board 16 but may be provided on the frame piece 25 instead.

The detection board having such a configuration has the power distribution board 16 at its right end.
The end portion of the signal output portion 19 protrudes slightly, and the signal output portion 19 ,
(The right ends of the X-shaped take-out portion 21 and the power feed paths 24, 24 are exposed to the outside. Also, as described above, the right end of the power feed path 7 of the first heating member 5 is exposed from the front surface.

Since the measuring electrode 12 is exposed in the direction F through the hole 4 of the protection plate 3, in order to prevent the measuring electrode 12 from being corroded by the measuring gas, the hole 2 may be filled with a porous copper coat 30 if desired.
The measurement electrode 12'- may be protected by filling it with

The detection board is installed inside the casing of the oxygen sensor, and is connected to the signal extraction section 19. Signal extraction section 21 and power supply line 7
, 7.24.74, the required power distribution is applied to the right end of 74, and the inflow [
A reference gas having a known oxygen partial pressure, such as air, is supplied to the hole 17 from 126a through the cavity 26, and the reference electrode 11 of the detection element plate 9'' is exposed to the reference gas. Further, the measuring electrode 12 in the dome portion is exposed to the measuring gas through the hole of the copper coat 30. Therefore, an electromotive force is generated due to the partial pressure difference between the overlapping books, and the signal is transmitted to the signal extraction section 19.2.
1.

At this time, since the first heating member 5 and the second heating member 22 are arranged at the lower part and the upper part of the detection element plate 9, respectively, when the temperature of the measurement scum is 300° C. or higher, the heating resistor 6.
3 from the feed line 7, 7.24° 24, and generates heat, the detecting element f-plate 9 becomes the same. It can be heated properly and uniformly from the beginning. No. 1 above. The second heating member 5.22 compensates the temperature of the sensing element-plate 9, making it possible to improve the detection value of the sensor.

Effect> As clarified from the above explanation, the unfired 1!1 is the detection element plate 9. Protective plate 14. Power distribution board 16 and one body 2
By sequentially joining the electrodes 3 and 9, the structure is configured such that the power distribution of the electrodes 3 and 4 and the flow path for the reference waste are created, and the solid electrolyte is provided only in the electrode part, and furthermore, the solid electrolyte is provided only in the electrode part. Second heating member 5, 2
2, since the detection element plate 9 can be heated from the lF plane, 1) it can be formed by joining plate materials, so manufacturing can be done in the cylinder;

2) The detection substrate can be constructed at low cost since the amount of 1M solid material used is minimal.

3) The conductive path 18.20 connects the power distribution board 1 to the detection element board 9.
6 is already insulated, and noise signals can be prevented without the need to provide a new insulating layer.

4) 1st. By energizing the second heating member 5.22, the solid electrolyte 3 can be uniformly and optimally heated, and the overlapping density can be detected as accurately as possible without being affected by the surrounding temperature environment.

5) 1st. There is an advantage that no new supporting plate material is required for attaching the second heating member 5, 220, and the temperature compensation can be performed with a small number of parts.

[Brief explanation of drawings]

The accompanying drawings show embodiments of the present invention, and FIG. 1 is a longitudinal cross-sectional side view of the detection board, FIG. It is 4.

Claims (1)

[Scope of Claims] 1) On the lower surface of the insulator in which a hole is formed, a first heat generating resistor located around the hole and a power supply path for the resistor is provided.
A heating member is arranged, and the heating member is covered from below with a protection plate, and a reference electrode is formed on the upper surface of a small plate-shaped piece made of solid electrolyte on the upper surface of the insulator, and a measurement electrode is formed on the lower surface exposed to the measurement gas. and disposing a detection element plate in which the measurement electrode is electrically connected to a connection end formed on the upper surface side, and disposing a protection plate adjacent to the detection element plate on the upper surface of the insulator, A power distribution board is arranged so as to cover the detection element board and the protection board from the top surface, and the power distribution board has a hole that opens at the top of the reference pole, and a reference whose one end is connected to the reference pole. A side conductive path and a measurement side conductive path whose one end is connected to the connection end of the measurement electrode are provided, and the upper surface of the distribution board includes a heating resistor located around the hole of the distribution board, and a heating resistor of the resistor. A detection board for an oxygen sensor, characterized in that a second heating member comprising a power supply path is disposed, and the upper surface of the power distribution board is further covered with a lid having a flow path communicating with the hole.