JP2000283950A - Gas detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect an inflammable gas concentration without being affected by miscellaneous gas existing in a measuring atmosphere, and to provide high detection precision. SOLUTION: This gas detector is a detector for detecting an inflammable gas concentration generated in a measured chamber A, a residual oxygen concentration inside the measured chamber A is measured by the first oxygen sensor part 2 of a limiting current type having a pair of electrodes 22, 23 in both faces of a zirconia substrate 21 of an oxide ion conductive solid electrolyte, after the inflammable gas generated reacts with oxygen in atmospheric gas, and an oxygen concentration in an outside space D where the atmospheric gas introduced into the chamber A exists is measured, on the other hand, by the second oxygen sensor part 3 of a limiting current type having a pair of electrodes 32, 33 in both faces of a zirconia substrate 31. Since gas components.concentrations excepting the inflammable gas are the same in the gas in the chamber A and the gas in the space D, influences caused by the miscellaneous gas components such as a steam containned in the atmospheric gas are corrected based on a detection result by the second oxygen sensor part 3 so as to accurately detect the inflammable gas concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to hydrogen, hydrocarbons,
The present invention relates to a gas detection device for detecting generation of a combustible gas component such as carbon oxide.

[0002]

2. Description of the Related Art As a gas detection device for detecting a combustible gas, for example, a contact combustion type gas sensor and a semiconductor type gas sensor are known. The former uses a platinum wire coil coated with a platinum catalyst together with an alumina carrier, and a combustible gas is brought into contact with the surface of a sintered gas detection element and burns, and the combustible gas concentration is detected from the temperature rise at that time. Is to detect the concentration of the flammable gas from the change in electric resistance when the flammable gas is adsorbed on the surface of the metal oxide semiconductor. However, these conventional flammable gas sensors have the advantage that the flammable gas can be directly detected, but have a problem that the detection concentration range is limited.

On the other hand, it is known that an oxygen sensor using an oxygen ion conductive solid electrolyte such as zirconia can accurately detect an oxygen concentration in a wide concentration range. NOx, it has been studied to detect the gas concentration other than oxygen, such as CO _2.
Since these gases are decomposed to generate oxygen, it is possible to detect the gas concentration from the resulting change in oxygen concentration. For example, in a humidity detection device disclosed in Japanese Patent Publication No. 6-60884, two independent spaces are formed in a zirconia solid electrolyte, and a pair of electrodes are provided inside and outside a wall surface forming each space. One of the pair of electrodes has a low voltage (for example, about 0.20 to 1.2 V) in which a limiting current based on only oxygen gas flows, and the other has a small voltage in which a limiting current based on decomposition of oxygen gas and water vapor flows. A high voltage (for example, about 1.1 to 1.8 V) is applied, and the humidity (water vapor concentration) in the measurement gas is detected from the difference between the current values flowing between the pair of electrodes.

[0004]

Therefore, it is conceivable to detect the flammable gas concentration by utilizing the change in the oxygen concentration due to the combustion of the flammable gas. However, the oxygen sensor has a problem that the detection value fluctuates due to a gas other than the measurement target gas present in the atmospheric gas. For example, when detecting hydrogen generated in the battery compartment of an electric or hybrid vehicle, the detection value fluctuates due to the effect of atmospheric humidity (water vapor) introduced into the battery compartment. Is difficult.

In the above-mentioned conventional humidity detecting device, a comparative oxygen sensor is provided which is supplied with the gas to be measured under the same conditions and is driven at a voltage at which the water vapor to be measured is not decomposed. Is to be detected. However, the flammable gas targeted by the present invention, particularly a highly reactive gas such as hydrogen, easily reacts with the surrounding oxygen. It cannot be applied immediately.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to enable accurate detection of a flammable gas concentration without being affected by another gas present in a measurement atmosphere. An object of the present invention is to provide a gas detection device having excellent detection accuracy.

[0007]

According to a first aspect of the present invention, there is provided a gas detecting apparatus for detecting a concentration of a combustible gas generated in a measurement chamber into which an atmospheric gas containing oxygen is introduced from an external space. A first oxygen having an oxygen ion conductive solid electrolyte and a pair of electrodes provided on the surface thereof, and measuring a residual oxygen concentration in the chamber to be measured after the combustible gas and oxygen in the atmosphere gas have reacted. A second oxygen sensor having a sensor unit, an oxygen ion conductive solid electrolyte, and a pair of electrodes provided on the surface thereof, for measuring an oxygen concentration in the external space where the atmospheric gas introduced into the chamber to be measured exists; And an oxygen concentration value in which the influence of the miscellaneous gas components contained in the atmospheric gas is corrected based on the detection values of the first and second oxygen sensor units and the second oxygen sensor unit. Flammable gas And a correction means for determining the concentration.

In the above configuration, the first oxygen sensor section contains a gas containing a flammable gas generated in the chamber to be measured, and the second oxygen sensor section contains a flammable gas before being introduced into the chamber to be measured. Free gas is introduced. The first oxygen sensor detects the concentration of oxygen remaining after the combustible gas has reacted with the surrounding oxygen, and the second oxygen sensor detects the oxygen concentration in the absence of the combustible gas. These detected values fluctuate when there are miscellaneous gas components such as water vapor in the atmosphere. However, since the gases introduced into both sensor units have the same gas components and concentrations other than flammable gas, the second oxygen sensor Based on the detection result of the part, the influence of miscellaneous gas components such as water vapor contained in the atmospheric gas can be corrected. Therefore, it is possible to correct the detection result of the first oxygen sensor unit using the correction means, accurately detect the decrease amount of oxygen based on the flammable gas, and accurately detect the concentration of the flammable gas. is there.

In the second aspect of the present invention, the first oxygen sensor section is provided with the pair of electrodes on opposite surfaces of the oxygen ion conductive solid electrolyte, and one of the electrodes is connected to the inside of the chamber to be measured. A limiting current type oxygen sensor structure in which the gas containing the combustible gas is exposed to the first internal space through which the gas is introduced through the diffusion resistance means, and when a predetermined voltage is applied to the pair of electrodes, The residual oxygen concentration is measured based on the value of the current flowing between the electrodes. Further, the second oxygen sensor section is provided with the pair of electrodes on opposite surfaces of the oxygen ion conductive solid electrolyte, and one of the electrodes is connected to the atmosphere gas existing in the external space by a diffusion resistance means. Has a limiting current type oxygen sensor structure exposed to the second internal space introduced through the, based on the value of current flowing between both electrodes when a predetermined voltage is applied to the pair of electrodes, The oxygen concentration in the external space is measured.

When a predetermined voltage is applied between a pair of electrodes of a limiting current type oxygen sensor, a limiting current corresponding to the oxygen concentration in the measurement atmosphere flows through the diffusion resistor. By measuring this current value, the oxygen concentration can be detected in a wide range,
The detection of flammable gas can be carried out until about 21% of oxygen contained in the atmosphere is completely consumed. Therefore, by forming the first and second oxygen sensor sections to have a limiting current type oxygen sensor structure, the flammable gas can be accurately detected in a wide concentration range.

According to the third aspect of the present invention, the constituent members of the first oxygen sensor section and the second oxygen sensor section are laminated and integrally formed. This makes it possible to make the device configuration compact and facilitate installation of the sensor.

According to a fourth aspect of the present invention, a laminate of the first oxygen sensor section and the second oxygen sensor section is inserted and arranged in the chamber to be measured, and the other electrode of the first oxygen sensor section is connected to the second electrode section. An introduction path for introducing the atmospheric gas from the external space is provided in the second internal space of the second oxygen sensor unit, which is exposed in the chamber to be measured. Also, a cover member is provided to cover the other electrode of the second oxygen sensor section, and the cover member is opened to the external space.

Specifically, as in the above configuration, the first
In addition, the stacked body of the second oxygen sensor unit may be inserted into the measurement chamber, and a pair of electrodes may be provided at the insertion ends. At this time, if the other electrode of the second oxygen sensor is exposed to the chamber to be measured, the oxygen concentration in the vicinity may change due to oxygen discharged from the second oxygen sensor. This can be avoided by providing.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a gas detection device according to the present invention. As shown in FIG. 1, a gas detection device 1 includes a first oxygen sensor for detecting an oxygen concentration in a measurement target chamber A where flammable gas is generated. A second part for detecting an oxygen concentration in the external space B in which the atmosphere gas (a gas having a gas component and concentration other than the flammable gas which is the same as the gas in the measurement room A) to be introduced into the measurement room; An oxygen sensor unit 3 and an arithmetic unit 4 as arithmetic means for arithmetically processing detection signals from the sensor units 2 and 3 to calculate an oxygen concentration corrected for the influence of gas components other than flammable gas are provided. I have. Examples of the combustible gas to be measured in the present invention include hydrogen, hydrocarbon, carbon monoxide, and the like.

FIG. 2 is a sectional view showing a specific structure of the first oxygen sensor unit 2 and the second oxygen sensor unit 3, and FIG.
FIG. As shown in FIG. 2, the first oxygen sensor unit 2 includes a plate-shaped body 21 (hereinafter, referred to as a zirconia substrate 21) made of zirconia (ZrO ₂ ), which is an oxygen ion conductive solid electrolyte, and opposed positions of upper and lower surfaces thereof. Has a pair of electrodes 22 and 23 formed on the substrate. The pair of electrodes 22 and 23 are made of platinum, and are formed by, for example, a screen printing method. Among them, the upper electrode 22 is arranged so as to be exposed to the above-mentioned measurement chamber A where the combustible gas exists,
The lower electrode 23 is exposed in a first internal space C provided below the zirconia substrate 21. The first internal space C is
It is formed in a spacer 24 made of alumina laminated below the zirconia substrate 21. The first internal space C includes a zirconia substrate 21 and a pair of electrodes 22, 2.
3 is communicated with the measured chamber A via a pinhole 25 which is a diffusion resistance means provided through the center. The size of the pinhole 25 is appropriately set such that the gas introduced into the first internal space C through the pinhole 25 has a predetermined diffusion rate.

The second oxygen sensor section 3 has substantially the same structure as the first oxygen sensor section 2 and has a zirconia substrate 31 and a pair of platinum electrodes 32, 33 formed by screen printing on opposing upper and lower surfaces thereof. have. Among them, the lower electrode 32 is exposed to the external space B where the atmospheric gas introduced into the measurement chamber A exists, and the upper electrode 33 is exposed to the second internal space D provided above the zirconia substrate 31. ing. The second internal space D is formed in a spacer 34 made of alumina laminated above the zirconia substrate 31. Further, the second internal space D includes a zirconia substrate 31.
And, it communicates with the external space B via a pinhole 35 which is a diffusion resistance means provided through the center of the pair of electrodes 32 and 33.

First oxygen sensor 2 and second oxygen sensor 3
Is formed by laminating the heater electrode 53 between the alumina plates 51 and 52, and is integrally laminated with the heater 5 common to both the sensor units 2 and 3 interposed therebetween. The heater electrode 53 is made of platinum,
It is formed by a screen printing method. As shown in FIGS. 2 and 3, the heater 5 includes a spacer 3 of the second oxygen sensor unit 3.
4 are provided with spacers 3 on the lead portions 5a and 5b formed on the surface.
4. Connected via a lead portion 5c embedded in the alumina plate 52. Further, the lower electrode 3 of the second oxygen sensor unit 3
2 is a lead portion 32a, and the upper electrode 32 is a lead portion 3c via a lead portion 33c embedded in the zirconia substrate 31.
3b. The upper electrode 22 of the first oxygen sensor 2 is connected to the zirconia substrate 2 of the first oxygen sensor 2.
The lower electrode 22 is connected to a lead portion 22a formed on one surface and a lead portion 23b via a lead portion 23c embedded in the zirconia substrate 21, respectively. The positions of the lead portions 22a and 23b are indicated by dotted lines in FIG.

The operation of the gas detection device 1 having the above configuration will be described. The gas detection device 1 has a wall surface of the measurement target chamber A such that the pinhole 25 of the first oxygen sensor part 2 faces the measurement target chamber A and the pinhole 36 of the second oxygen sensor part 3 faces the external space B. Fixed to In the first internal space C of the first oxygen sensor unit 2, a gas in the measurement target chamber including a combustible gas to be measured (here, for example, hydrogen) passes through the pinhole 25 from the measurement target chamber A. Penetrates by diffusion through. The pair of electrodes 22 and 23 of the first oxygen sensor unit 2
Is a predetermined DC voltage (usually 0.5 to
When a voltage of about 1.0 V is applied, oxygen in the gas to be measured is electrolyzed on the electrode 23 to become oxygen ions and moves inside the zirconia substrate 21 toward the electrode 22. The applied voltage at this time is set so that the flowing current becomes a value at which the diffusion of oxygen in the pinhole 25 is rate-determined, that is, a so-called limiting current. The oxygen and hydrogen react between the pair of electrodes 22 and 23. After that, a limiting current flows according to the concentration of oxygen remaining.

On the other hand, in the second internal space D of the second oxygen sensor section 3, an atmosphere gas having the same gas composition and concentration as the gas in the chamber A other than hydrogen is supplied from the external space B to the pinhole 35. Invades by diffusion through Second oxygen sensor unit 3
When a DC voltage of the same voltage of the first oxygen sensor unit 2 is applied to the pair of electrodes 32 and 33 so that the electrode 32 becomes a positive electrode, oxygen in the atmospheric gas is electrolyzed on the electrode 33 to form oxygen ions. As a result, the inside of the zirconia substrate 31 moves to the electrode 32 side. At this time, a limit current flows between the pair of electrodes 32 and 33 according to the concentration of oxygen in the atmospheric gas. This makes it possible to know the oxygen concentration in the atmospheric gas in a state where no flammable gas exists.

The output of the first oxygen sensor section 2 is
If flammable gas is present inside, it will decrease as follows. (1) Reduction of oxygen partial pressure by flammable gas (2) Consumption of oxygen by oxidation of flammable gas (3) Reduction of oxygen partial pressure by oxidation reaction product The flammable gas is hydrogen (concentration: x%) In this case, the oxygen concentration decreases as in the following equation. FIG. 4 shows the relationship between the oxygen concentration and the hydrogen concentration at this time (when the initial oxygen concentration is 21%). Oxygen concentration (%) = ｛21 × [(100−x) / 100]
−x / 2｝ × [(100−x) / 100]

Since the output of the first oxygen sensor section 2 indicates the decreased oxygen concentration as an output value, if the oxygen concentration in the hydrogen-free atmosphere gas (the oxygen concentration before the decrease) is always constant, the output decreases. The hydrogen concentration can be detected only by the output value of the oxygen concentration. However, for example, when detecting the generation of hydrogen in the battery compartment of a hybrid vehicle, since the atmosphere in the vehicle compartment, which is the external space B, is introduced into the battery compartment serving as the measured chamber A, changes in humidity and carbon dioxide Depending on the amount,
The output of the first oxygen sensor unit 2 fluctuates. Therefore, in the present invention, the oxygen concentration in the atmosphere gas containing no hydrogen, that is, the oxygen concentration in the external space B is detected by using the second oxygen sensor unit 3, and the oxygen concentration in the first oxygen sensor unit 2 is detected based on the detected oxygen concentration. Correct the output. The computing device 4 serving as a correction unit computes the amount of decrease in oxygen from the output difference between the first oxygen sensor unit 2 and the second oxygen sensor unit 3, and indirectly computes the flammable gas concentration from the result. Since the gases introduced into the first oxygen sensor unit 2 and the second oxygen sensor unit 3 have the same gas components and concentrations other than flammable gas, various gases such as humidity (water vapor) in the atmospheric gas and carbon dioxide Can be corrected. In addition, the limiting current type oxygen sensor used in this embodiment is:
Oxygen concentration can be detected in the range of almost 0 to 100%,
Since the flammable gas can be detected until the oxygen contained in the atmosphere at about 21% is completely consumed, the flammable gas can be accurately detected in a wide concentration range.

FIG. 5 shows a second embodiment of the present invention. The basic configuration of the present embodiment is the same as that of the first embodiment, and FIG. 5A shows a sensor element including a stacked body of the first oxygen sensor unit 2 and the second oxygen sensor unit 3 in the present embodiment. FIG. 5B shows an exploded view of the configuration. FIG.
As shown in (a) and (b), the first oxygen sensor unit 2
On one end side (left end in the figure) of the zirconia substrate 21,
A pair of platinum electrodes 2 formed at opposing positions of the upper and lower surfaces
2 and 23, the upper electrode 22 is in the chamber A where the combustible gas is present, and the lower electrode 23 is in the zirconia substrate 2
The lower spacer 24 is disposed so as to be exposed in a first internal space C formed at the left end of the spacer 24. The first internal space C is
It communicates with the measured chamber A through a pinhole 25 which is a diffusion resistance means.

The second oxygen sensor section 3 is formed below the first oxygen sensor section 2 with a heater 5 interposed therebetween, and a spacer 34 and a zirconia substrate 31 are sequentially stacked below the heater 5. At the left end of the zirconia substrate 31, a pair of platinum electrodes 32 and 33 are formed at opposing positions on the upper and lower surfaces.
Are arranged so as to be exposed in a second internal space D formed at the left end of the spacer 34. In the present embodiment, an introduction path E extending to the right end from the second internal space D is formed in the spacer 34 as diffusion resistance means, and the second internal space D is connected to the outside through the introduction path E. It communicates with the space B.

A pair of electrodes 22, 2 of the first oxygen sensor section 2
3 are connected to lead portions 22a and 23b extending rightward along the upper and lower surfaces of the zirconia substrate 21, respectively. Similarly, a pair of electrodes 32, 33 of the second oxygen sensor section 3 are connected to lead sections 32 formed on the upper and lower surfaces of the zirconia substrate 31.
a and 33b, and the heater 5 is connected to the lead portions 5a and 5b, respectively. These lead portions 22a, 23b, 32
The right ends of a, 33b, 5a, and 5b are connected to an external power supply.

In the gas detection device having the above-described structure, the sensor element is inserted into the chamber A to be measured at the left end in the figure, and is fixed to the wall of the chamber A so that the right end is located in the external space B.
In the first internal space C of the first oxygen sensor section 2, a gas in the measurement target chamber A including a combustible gas (for example, hydrogen) to be measured is filled with the second internal space of the second oxygen sensor section 3. D has
An atmosphere gas containing no combustible gas in the external space B is introduced through the communication passage E. The operation of the first oxygen sensor unit 2 and the second oxygen sensor unit 3 is the same as that of the first embodiment, and even with such a configuration, it is possible to detect the flammable gas concentration in the chamber A to be measured. Can be.

FIG. 6 shows a third embodiment of the present invention. In the configuration of the second embodiment, since oxygen is discharged from the second internal space D to the lower electrode 32 facing the chamber A to be measured in the second oxygen sensor section 3, the vicinity of the sensor element The oxygen concentration may fluctuate due to the discharged oxygen. Therefore, in the present embodiment, FIG.
As shown in (a) and (b), spacers 36 and 37 are laminated on the lower surface of the zirconia substrate 31 as a cover member that covers the lower surface of the second oxygen sensor unit 3. In the spacer 36,
A space 36a corresponding to the lower electrode 32 and a passage 36b communicating therewith and reaching the right end of the spacer 36 are formed. The spacer 37 extends to near the right end of the sensor element so that the passage 36b opens to the external space D.

According to the above configuration, oxygen discharged to the lower electrode 32 side is discharged to the external space D through the space 36a and the passage 36b, so that there is no possibility that the oxygen concentration near the sensor element fluctuates. Accurate detection is possible.

FIGS. 7 and 8 show a third embodiment of the present invention. FIG. 7 shows an example in which the gas detection device of the present embodiment is applied to a charge / discharge control system for a hybrid vehicle. In FIG. 7, an upper part of a battery chamber 6 serving as a measured chamber having a plurality of nickel-metal hydride batteries is shown. A hydrogen sensor 7 including a first oxygen sensor section 2 and a second oxygen sensor section 3 is fixed to the wall, and detects hydrogen generated in the battery chamber 6. The detection result of the hydrogen sensor 7 is supplied to a battery ECU 8 serving as a correction unit.
, The battery ECU 8 determines the hydrogen concentration based on this, and controls the charging and discharging of the battery.

FIG. 8 (a) shows a specific configuration of the hydrogen sensor 7, and a tubular case 71 fixed to the wall of the battery chamber 6 is shown.
A flat sensor element 72 is accommodated therein. A space between the case 71 and the sensor element 72 is filled with a heat insulating member 73 and a gas sealing material 74. The lower end of the case 71 is inserted through the battery chamber 6, and an open end is provided with a hemispherical explosion-proof wire mesh 75 for preventing flame propagation. When detecting a flammable gas such as hydrogen, if the sensor element 72 is heated to a high temperature by a heater, flammable gas may be ignited in the vicinity of the element. Prevents spreading. In order to prevent the explosion-proof wire mesh 75 from being damaged, a container-shaped protection member 76 is provided so as to protect the periphery thereof. Note that a plurality of through holes 76a for introducing gas in the battery chamber 6 into the sensor are provided on the lower end surface of the protection member 76.

As shown in FIG. 8 (b), the sensor element 72 has a zirconia substrate 77 common to the first oxygen sensor 2 and the second oxygen sensor 3, and is made of alumina disposed below the zirconia substrate 77. In the spacer 78, a first internal space C and a second internal space D defined by the partition wall 78a are formed. The second internal space D extends to the left end of the spacer 78 and opens in the upper end portion (FIG. 8A) of the case 71 into which the atmosphere in the vehicle interior, which is the external space, is introduced. The pair of electrodes 22 and 23 of the first oxygen sensor unit 2 are configured such that one electrode 22 has a case 71 into which gas in the battery chamber 6 is introduced.
Inside, the other electrode 23 is exposed to the first internal space C, and a pair of electrodes 32 and 33 of the second oxygen sensor unit 3 are provided.
The one electrode 32 is exposed in the case 71 and the other electrode 33 is exposed in the second internal space D. Below the spacer 78, the heater 5 having a heater electrode 53 made of platinum embedded between the alumina substrates 51 and 52 is laminated.

In the battery chamber 6, when the battery is overcharged or overdischarged, hydrogen and oxygen are generated by electrolysis of water in the electrolytic solution as shown in the following equation. Positive electrode 2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ Negative electrode 4OH ⁻ → 2H ₂ O + O ₂ + 4e ⁻ That is, overcharge or overdischarge of the battery can be detected by detecting the generation of hydrogen.

Therefore, using the hydrogen sensor 7 having the above structure,
The detection values of the first oxygen sensor unit 2 and the second oxygen sensor unit 3 are
The data is input to the battery ECU 8 having the correction means. The operations of the first oxygen sensor unit 2 and the second oxygen sensor unit 3 are the same as those in the above embodiments, and the battery ECU 8 corrects the influence of the miscellaneous gas in the atmosphere in the vehicle cabin based on the operation, and Determine the concentration. Then, when the generation of hydrogen is detected to be equal to or more than the predetermined value, it is determined that the battery is overcharged or overdischarged, and the charging and discharging of the battery is controlled.

As described above, the gas detection device of the present invention can be used as a hydrogen detection device and used for overcharge / overdischarge control of a hybrid vehicle. Further, as shown in FIG. 8, the sensor element 72 can be made more compact by forming the first oxygen sensor section 2 and the second oxygen sensor section 3 using the common zirconia substrate 77.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a gas detection device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a first oxygen sensor unit and a second oxygen sensor unit according to the first embodiment.

FIG. 3 is a bottom view of FIG. 2;

FIG. 4 is a diagram showing the relationship between oxygen concentration and hydrogen concentration.

FIG. 5A is a cross-sectional view illustrating a configuration of a first oxygen sensor unit and a second oxygen sensor unit according to a second embodiment;
(B) is an exploded view of (a).

FIG. 6A is a cross-sectional view illustrating a configuration of a first oxygen sensor unit and a second oxygen sensor unit according to a third embodiment;
(B) is an exploded view of (a).

FIG. 7 is a diagram showing an overall configuration of a battery charge / discharge control system to which the present invention is applied.

8A is an overall sectional view of a hydrogen sensor used in the charge / discharge control system of FIG. 7, FIG. 8B is a plan view showing a sensor element configuration, and FIG. 8C is an AA line of FIG. It is sectional drawing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas detection apparatus 2 1st oxygen sensor part 21 Zirconia substrate (oxygen ion conductive solid electrolyte) 22, 23 A pair of electrodes 25 Pinhole (diffusion resistance means) 3 2nd oxygen sensor part 31 Zirconia substrate (oxygen ion conductive solid) Electrolyte) 32, 33 A pair of electrodes 35 Pinhole (diffusion resistance means) 36, 37 Spacer (cover member) 4 Computing device (correction means) 5 Heater A Room under measurement B External space C First internal space D Second Interior space

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuhiko Yoshida 14 Iwatani, Shimowasukamachi, Nishio City, Aichi Prefecture Inside the Japan Auto Parts Research Institute (72) Inventor Yoshimasa Kodama 14 Iwatani, Shimowasukamachi, Nishio City, Aichi Prefecture Shares (72) Inventor Kazuo Toshima 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Masanori Iwase 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Toshitaka Saito 1-1-1 Showa-cho, Kariya-shi, Aichi Prefecture Inside DENSO Corporation

Claims (4)

[Claims] 1. A gas detector for detecting the concentration of flammable gas generated in a measurement chamber into which an atmospheric gas containing oxygen is introduced from an external space, comprising: an oxygen ion conductive solid electrolyte; A first oxygen sensor section having a pair of electrodes, for measuring the residual oxygen concentration in the chamber to be measured after the combustible gas and oxygen in the atmospheric gas have reacted, and an oxygen ion conductive solid electrolyte and A second oxygen sensor unit having a pair of electrodes provided on a surface thereof and measuring an oxygen concentration in the external space in which the atmospheric gas is present; and a detection value of the first oxygen sensor unit and a second oxygen sensor unit. It is characterized by comprising a correcting means for calculating an oxygen concentration value in which the influence of the miscellaneous gas components contained in the atmospheric gas is corrected based on the detected value, and determining the concentration of the combustible gas from the oxygen concentration value. To be Gas detector. 2. The first oxygen sensor section, wherein the pair of electrodes are provided on opposite surfaces of the oxygen ion-conductive solid electrolyte, and one of the electrodes is connected to the flammable gas and the flammable gas in the chamber to be measured. A limiting current type oxygen sensor structure in which a gas containing the atmosphere gas is exposed to a first internal space through which the gas is introduced through a diffusion resistance means, and when a predetermined voltage is applied to the pair of electrodes, both electrodes are The second oxygen sensor unit is provided with the pair of electrodes on both opposite surfaces of the oxygen ion conductive solid electrolyte, based on a value of a current flowing between the electrodes. A limiting current type oxygen sensor structure in which one electrode is exposed to a second internal space into which the atmospheric gas present in the external space is introduced through a diffusion resistance means, and a predetermined current is applied to the pair of electrodes; Apply voltage Both electrodes between the based on the value of current flowing, the gas detection apparatus according to claim 1, wherein measures the oxygen concentration of the external space when the. 3. The gas detection device according to claim 2, wherein constituent members of said first oxygen sensor section and said second oxygen sensor section are laminated and integrally formed. 4. A laminated body of the first oxygen sensor section and the second oxygen sensor section is inserted and arranged in the chamber to be measured, and the other electrode of the first oxygen sensor section is exposed in the chamber to be measured. And, while providing an introduction path for introducing the atmospheric gas from the external space in the second internal space of the second oxygen sensor unit, a cover member for covering the other electrode of the second oxygen sensor unit is provided, 4. The gas detection device according to claim 3, wherein the cover member is opened to the external space.