JP3484586B2 - Composite gas sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite gas sensor capable of simultaneously detecting both a flammable gas leaking from a combustion instrument and an incomplete combustion gas such as carbon monoxide and hydrogen generated by incomplete combustion of the combustion instrument.

[0002]

2. Description of the Related Art There are two types of gas sensors used in gas leak detectors and incomplete combustion detectors. The first method is a semiconductor method, and the principle is that when an n-type oxide semiconductor such as tin oxide is heated in the atmosphere and flammable gas comes into contact with it, the electrical resistance of tin oxide is increased. It takes advantage of the fact that the value is greatly reduced.

This type of gas sensor can be manufactured at a relatively low cost because it requires only one sensor, has a relatively high sensitivity, and is a gas for city gas, liquefied petroleum gas, and the like. It is widely used as a sensor for leak detectors and a sensor for incomplete combustion detectors that detects low-concentration carbon monoxide gas. The second method is a catalytic combustion method, which uses a gas detection element having a structure in which a temperature measuring resistor made of a metal wire having a high resistance temperature coefficient is embedded inside an oxidation catalyst formed in a bead shape.

The operating principle of this sensor is that the combustible gas is catalytically oxidized on the surface of a heated oxidation catalyst, and the temperature rise of the sensor due to the combustion heat at this time is detected as a change in the electric resistance value of the resistance temperature detector. It is a thing. In this method, it is necessary to capture the minute change in the electrical resistance value due to the temperature rise of the sensor.Therefore, in general, a gas detection element that has the function of catalytically oxidizing combustible gas, and the same shape and combustibility It is used as a gas sensor having a structure in which a temperature compensation element that does not oxidize gas by contact is incorporated in each of two branch sides of a bridge circuit.

As described above, the catalytic combustion gas sensor has two
Although it requires individual elements, it is said that this type of gas sensor is less susceptible to coexisting moisture and that ambient temperature is less affected by the use of a temperature compensation element, so it is superior in reliability to semiconductor type sensors. There are features. From the above, the catalytic combustion type gas sensor is often used for gas leak detection in places where the usage environment is severe, such as kitchens and bathrooms.

[0006] In recent years, as the housing structure has become more sealed,
Incomplete combustion occurs while using the combustion equipment indoors, and the number of tragic accidents resulting in poisoning death due to carbon monoxide gas generated at this time tends to increase. Carbon monoxide gas is highly toxic to the human body even at an extremely low concentration.
In 00 ppm carbon monoxide gas, symptoms of headache and dizziness appear in 20 minutes and become unconscious in 50 minutes. Therefore, in order to promptly detect the incomplete combustion state and prevent accidents,
A gas sensor that can accurately detect low concentrations of carbon monoxide below 00ppm is required.

Conventionally, the gas leak detection device and the incomplete combustion detection device have been separate products. Among them, the gas leak detection device has become relatively popular in recent years under the guidance of the Ministry of International Trade and Industry. However, in reality, the incomplete combustion detector has a very low penetration rate as compared with the gas leak detector.

[0008] In order to stop the increasing tendency of such gas accidents, recently, a major gas company mainly provided one detector with both functions of gas leak detection and incomplete combustion detection, and promoted its popularization. The movement to pursue is increasing. As a composite detection device in which one detection device has two detection functions of gas leakage and incomplete combustion, there is the following configuration.

This detection device uses a so-called semiconductor sensor using the above tin oxide, and has two sensors for detecting methane and for detecting carbon monoxide gas (hereinafter referred to as CO). It is mounted on one detector. In the methane detection sensor of this composite detector, the tin oxide sintered body is constantly kept at about 400 ° C, and the decrease in electric resistance value when methane contacts this is detected as a change in current value.

On the other hand, for the CO detection sensor, a tin oxide sintered body similar to the methane detection sensor is used at about 100 ° C and about 300 ° C.
This is a so-called heat cleaning method in which two temperatures are alternately maintained, CO is detected on the low temperature side, and water in the gas adsorbed during low temperature operation is desorbed on the high temperature side. That is, the above-mentioned composite detector is nothing more than the conventional gas detector and incomplete combustion detector that are simply pushed into a single detector case.

[0011]

The conventional composite type detector has the following problems. Since the detection method is a semiconductor method, the detection accuracy decreases due to water vapor coexisting in the gas in both methane detection and CO detection. A semiconductor gas sensor using tin oxide has a property that when water vapor is present in the gas, the water vapor is chemically adsorbed on the surface of tin oxide and the electric resistance value thereof is lowered. Therefore, if water vapor is contained in the gas, an alarm tends to be issued at a concentration lower than the actual concentration of the detection component, causing an error in the detection accuracy of the detection target component (for example, methane or CO).

Since this phenomenon becomes more remarkable as the operating temperature of the sensor becomes lower, the sensor is operated at a low temperature such as 100 ° C.
In the case of a CO detection sensor, the effect is large. Methane, which is the main component of city gas, is lighter than air, so a gas leak detector is installed near the ceiling.However, when a semiconductor CO sensor is incorporated in this detector, it can be used especially in bathrooms and kitchens. In a high-temperature and high-humidity environment, the CO detector may malfunction even at a CO concentration at a level that has little effect on the human body.

The CO sensor used in the conventional hybrid detector cannot be continuously monitored for incomplete combustion because it operates periodically at two temperatures, 100 ° C. and 300 ° C. Therefore, for example, when the CO concentration rapidly increases in a small washroom or bathroom, the operation of the detector may be delayed and gas poisoning may occur. As described above, the incomplete combustion detector must be a continuous monitoring type detector that can immediately give an alarm when an incomplete combustion state occurs under any circumstances.

Since the conventional CO sensor is a system that periodically changes the sensor temperature, it is necessary to add a timer function to the power supply circuit of the sensor, and the circuit configuration becomes complicated. Since such a CO sensor will be integrated with a methane sensor, it is extremely difficult to supply an inexpensive hybrid detector. As mentioned above, conventional hybrid detectors are especially
There are problems that should be improved in terms of the practical reliability of the sensor and the cost of the detector.

An object of the present invention is to provide a composite gas sensor which does not have the above-mentioned problems and which can operate at a constant temperature and can always detect both a combustible gas having a low gas concentration of 1000 ppm and an incompletely combusted gas. To do.

[0016]

In order to achieve the above object, a metal oxide carrier carrying an oxidation catalyst is fixedly attached to a resistance temperature detector, and the oxidation catalyst is a first gas whose main component is palladium. The detection element, or the second gas detection element having the same structure as the first gas detection element, and the oxidation catalyst is mainly platinum, is provided with a first filter made of activated carbon or a noble metal catalyst. In a composite gas sensor in which any one of the second filters made of supported activated carbon is combined with any two gas detection units of the covered gas detection units, the combination of the gas detection units is the first Gas detection part in which the first filter is covered on the gas detection element, and a gas detection part in which the second filter is covered on the second gas detection element, or the first gas detection part It is assumed that the second filter is a gas detection unit which the said second gas sensing element and the gas detecting portion first filter are thus covered made is covered, the device. Hereinafter, these are referred to as a first composite sensor.

Further, a metal oxide carrier carrying an oxidation catalyst is fixed to the resistance temperature detector, and the oxidation catalyst is the same as the first gas detection element whose main component is palladium or the first gas detection element. The oxidation catalyst has a first filter made of activated carbon, a second filter made of activated carbon carrying a noble metal catalyst, or a gold detection catalyst in any of the second gas detection elements mainly containing platinum. A composite gas sensor in which four gas detection units are combined with any one of the third filters made of iron oxide carrying Fe, or the gas detection unit is covered with no filter. , The combination of gas detector is
A first group consisting of a set of two gas detectors each,
A gas detecting section including the first gas detecting element not covered with a filter and a gas detecting section including the second gas detecting element not covered with a filter, the first gas detecting element
Wherein the gas detecting portion in which the first filter is provided over the first of the filter and the gas detector comprising overlaid second gas sensing element, the second to the first gas detector element
A gas detecting section formed by covering the filter, a gas detecting section formed by covering the second gas detecting element by the second filter, and a gas detecting section formed by covering the first gas detecting element by the third filter. A gas detection unit and the second gas detection element covered with the third filter, or the first gas detection element covered with the first filter and the third filter And a second gas detecting element, and a second gas detecting element covered with the first filter and the third filter. Third consisting of divisions
Group, a gas detection section in which the first filter is covered with the first gas detection element and a gas detection section in which the second filter is covered with the first gas detection element, or A second gas detection element covered with the first filter; and a second gas detection element covered with the second filter,
And any one of the above. Hereinafter, these are referred to as a second composite sensor.

Further, a metal oxide carrier carrying an oxidation catalyst is fixed to the resistance temperature detector, and the oxidation catalyst is the same as the first gas detection element whose main component is palladium or the first gas detection element. The oxidation catalyst has a first filter made of activated carbon, a second filter made of activated carbon carrying a noble metal catalyst, or a gold detection catalyst in any of the second gas detection elements mainly containing platinum. A composite gas sensor in which four gas detection units are combined with any one of the third filters made of iron oxide carrying Fe, or the gas detection unit is covered with no filter. , The combination of gas detector is
Any one set of the first group, a fourth group consisting of each of the following two gas detection units, a gas detection unit consisting of the first gas detection element not covered by a filter, and The gas detection part in which the third filter is covered on the first gas detection element, the gas detection part in which the second gas detection element is not covered by the filter, and the third gas detection element are formed on the second gas detection element. Gas detection part formed by covering the first gas detection element, the gas detection part formed by covering the first gas detection element by the first filter and the first filter and the third gas detection element by the first gas detection element. Gas detection part formed by covering the second gas detection element and the gas detection part formed by covering the second gas detection element by the first filter, and the second filter formed by covering the second gas detection element by the first filter and the third filter. Covered with a filter Comprising gas detector, and made from either one set of. Hereinafter, these are referred to as a third composite sensor.

Further, a metal oxide carrier carrying an oxidation catalyst is fixed to the resistance temperature detector, and the oxidation catalyst is the same as the first gas detection element whose main component is palladium or the first gas detection element. The oxidation catalyst has a first filter made of activated carbon, a second filter made of activated carbon carrying a noble metal catalyst, or a gold detection catalyst in any of the second gas detection elements mainly containing platinum. A composite gas sensor in which four gas detection units are combined with any one of the third filters made of iron oxide carrying Fe, or the gas detection unit is covered with no filter. , The combination of gas detector is
A second group of loops each consisting of the following two gas detectors is provided for the second group, and a third gas detector is provided for the second gas detectors and the gas detectors for the first gas detector element not covered by the filter. A gas detecting part covered with a filter; a gas detecting part consisting of the second gas detecting element not covered with the filter; and a gas detecting part consisting of the first gas detecting element covered with the third filter, A gas detection unit in which the first filter is covered by the first gas detection element, and a gas detection unit in which the first filter and the third filter are covered by the second gas detection element; A gas detection unit in which the first filter is covered on the second gas detection element, and a gas detection unit in which the first filter and the third filter are covered on the first gas detection element; One of A set, and made from either one set of the fourth group. Hereinafter, these are referred to as a fourth composite sensor.

Further , according to any one of claims 2 to 4,
In the described composite gas sensor, the gas detection elements covered with the same type of filter may be housed in the same filter. Further, in the composite gas sensor, the resistance value of the resistance temperature detector of the gas detection element of the third group or the fourth group is equal to the resistance measurement value of the gas detection element of the first group or the second group. It is good to be 3 to 10 times the resistance value of the body.

[0021]

In the composite gas sensor of the present invention, a gas detecting section is formed by combining a gas detecting element and a filter, and a plurality of these gas detecting sections are combined together.
First, the individual functions of the gas detection element and the filter will be explained.
Next, the operation of the gas detector and the composite gas sensor will be described.

Palladium carried on the first gas detecting element (hereinafter referred to as E1) has an oxidizing activity for methane, CO, hydrogen and ethanol. Second gas detection element
Platinum supported on (hereinafter referred to as E2) has an oxidizing activity with respect to CO, hydrogen and ethanol. The first filter (hereinafter referred to as F1) is made of activated carbon, and the activated carbon physically adsorbs ethanol, so the filter allows methane, CO and hydrogen other than ethanol to pass through.

The second filter (hereinafter referred to as F2) is made of activated carbon carrying a noble metal catalyst, and the noble metal catalyst has an oxidizing activity for CO and hydrogen near room temperature. This filter allows F2 to permeate only methane because it overlaps with the action of activated carbon. The third filter (hereinafter referred to as F3) is made of iron oxide carrying a gold catalyst and has an oxidizing activity for CO, so
Permeates methane, hydrogen and ethanol.

According to the invention, the first composite gas sensor is a combination of two gas detectors, E1F1 and E2F2, or E1F2 and E2F1. Considering the combination of the actions of the above individual elements, the gas detector E1F1
The methane, CO, and hydrogen that have passed through the filter F1 are oxidized (combusted) by the gas detection element E1 inside. That is, it is sensitive to methane, CO and hydrogen. On the other hand, in the gas detector E2F2, methane that has permeated F2 is not oxidized by E2, and the gas detector element E2 inside does not oxidize any gas. That is, it has no sensitivity to any gas. Therefore, when the gas detection unit E1F1 and the gas detection unit E2F2 are incorporated in the two sides of the bridge circuit, the gas detection unit E2F2 actually acts as a compensation unit and can have a bridge output for methane, CO and hydrogen. .

It is important that the latter combination of E1F2 and E2F1 is incorporated in a bridge circuit. The gas detector E1F2 is sensitive only to methane. The gas detector E2F1 is sensitive to CO and hydrogen. Thus, the bridge output can be output, ie have bridge outputs for methane, CO and hydrogen, except when both gas detectors are sensitive or not sensitive at the same time.

The second composite gas sensor includes a gas detector 4
The first group, E1 and E
2, E1F1 and E2F1, E1F2 and E2F2, E1F3 and E2F3, or E1F1F
A third group consisting of one set of 3 and E2F1F3 and the other two gas detectors, E1F1 and E1F2, or E2F1 and E2
It consists of one pair of F2. Similar to the above, due to the combined action of the gas sensing element and the filter, the bridge output of the first group can have a bridge output for methane only and the bridge output of the third group for CO and hydrogen. Can have a bridge output.

The second composite gas sensor uses two bridge circuits, which makes it possible to distinguish between methane and CO and hydrogen. The third composite gas sensor consists of four gas detectors, the combination of which is one set of the first group and a fourth group of two other gas detectors, E1 and E1F3. , E2 and E2F3, E1F1 and E1F1F
3 or one of E2F1 and E2F1F3.

Similarly to the above, in the fourth group,
It can have a bridge output only for CO. Therefore, the third composite gas sensor can distinguish between methane and CO. The fourth composite gas sensor consists of four gas detectors, a second group of two gas detectors, E1 and E2F3, E2 and E1F3, E1F1 and E2F1F3, or E2.
It consists of one set of any one of F1 and E1F1F3 and one set of any of the fourth group consisting of two gas detectors.

Similarly to the above, in the second group,
Output may have a bridge output only for methane and CO to CO is output smaller than against the methane. Therefore, the fourth composite gas sensor can distinguish between methane and CO. In the composite gas sensor, the resistance values of the resistance temperature detectors of the gas detection elements of the third group or the fourth group are the resistance values of the resistance temperature detectors of the gas detection elements of the first group and the second group. When the resistance value is 3 to 10 times, CO is several hundred ppm, and methane is several thousand ppm, which is different from the actual detected concentration by about one digit.
Bridge outputs can be similar.

[0030]

【Example】

Example 1 FIG. 1 is a diagram of a composite gas sensor according to an example of the present invention.
(A) is sectional drawing of a gas detection part, (b) is sectional drawing of a detection part which becomes a pair. The gas detection element 11 comprises 5 wt% of palladium supported on an activated alumina carrier having a specific surface area of 150 m ² / gr which is sintered on a platinum coil having a wire diameter of 50 μm. Both ends of the platinum coil are two metal pins standing on an insulating base 3a.
Welded to 4. Further, the base 3a is provided with an explosion-proof wire net 20a made of two 100-mesh wire nets so as to cover the gas detection element 11.

On the other hand, on the outside of the wire net 20a, a filter 21a made of activated carbon is mounted in a cylindrical shape to form a gas detector S11. This activated carbon filter 21a is a cylindrical molded body of fibrous activated carbon FR-15 made by Kuraray Chemical Co., Ltd., and is supported by contacting with the inner cylindrical surface of the cap 21k on the outer side of the cap 21k. It consists of a metal net and an airtight ceiling plate.

The gas detection element 12 comprises a carrier similar to that of the gas detection element 11 and 5 wt% of a platinum catalyst supported thereon. The structure of this gas detection unit S22 is the same as that of the gas detection unit 11, except that the material of the filter 22a is different, and the filter 22a includes a molded body of activated carbon in which the activated carbon filter 21a carries a platinum catalyst at 7 wt%. It is filled with 22f. Gas detector S2
2 methane, CO, because no sensitivity to hydrogen and ethanol, is substantially a compensation unit (see section effects).

The above-mentioned gas detector S11 and gas detector S22 were incorporated into a bridge circuit, and the output for each gas component of methane, CO, hydrogen and ethanol was evaluated. FIG. 2 is a graph of the bridge output of the composite gas sensor of this one embodiment. 1M, 1C, 1H and 1E are bridge outputs for methane, CO, hydrogen and ethanol, respectively. As shown in FIG. 2, the composite gas sensor of the present invention has three types of methane, CO and hydrogen.
It can be seen that it has sensitivity to the gas of the components, and has no sensitivity to the smoke of sake or ethanol produced during cooking such as mirin. Example 2 This composite gas sensor consists of four gas detectors. Figure 3
FIG. 4 is a diagram of a composite gas sensor according to another embodiment of the present invention,
(A) is a cross-sectional view of the methane detection unit S1, (b) is a cross-sectional view of the gas detection unit S2 to be paired with it, (c) is a cross-sectional view of the CO and hydrogen detection unit S21x, (d) this Gas detector S22x
FIG.

In this embodiment, in order to balance the gas detection output, a coil made of a platinum wire having a wire diameter of 50 μm was used for the gas detection elements 11 and 12 of the methane detection section S1 and the paired gas detection sections S2. On the other hand, a gas detector element for a CO / hydrogen detector pair
A coil made of platinum wire with a wire diameter of 15 μm is used for 12x, and the number of turns of the coil is set to be larger than that of the gas detection element of the methane detection unit, and the electrical resistance of the coil is about 7 times that of the element of the methane detection unit. A large one was used. It should be noted that, in order to unify the gas detection function of the present invention as a whole and facilitate understanding, the same reference numerals are used when the gas detection units have the same configuration.

Methane detector S1 and paired gas detector S2
Is a gas detector element 1 on pin 4 of the individual base 3a.
Only 1 and 12 are welded and the wire mesh 20a is covered,
The filter is not covered. CO, hydrogen detector S21x is the base
The gas detection element 12x of a platinum coil of high resistance is welded to the pin 4 of 3a, covered with the wire net 20a, and further covered with the activated carbon filter 21a in the first embodiment. CO, hydrogen detector S2
The gas detection unit paired with 1x is S22x.

The methane detection unit S1 and the paired gas detection unit S2 are incorporated into a bridge circuit, respectively, and CO and hydrogen detection units S21x
The paired gas detectors S22x and S22x were incorporated in different bridge circuits, and the outputs for the respective gas components of methane, CO, hydrogen, and ethanol were evaluated in the same manner as in Example 1. FIG. 4 is a graph of bridge output for methane, CO, hydrogen, and ethanol of the methane detection pair. 21M, 21C, 21H and 21
E is the bridge output for methane, CO, hydrogen and ethanol. It can be seen from Fig. 4 that it is sensitive only to methane.

FIG. 5 is a graph of bridge outputs for methane, CO, hydrogen, and ethanol of the CO, hydrogen detection pair.
22M, 22C, 22H and 22E are bridge outputs for methane, CO, hydrogen and ethanol. It can be seen from Fig. 5 that it has sensitivity only to CO and hydrogen. That is, by using the composite gas sensor including the four gas detection units of the present invention, gas leakage and incomplete combustion can be detected separately. Example 3 This composite gas sensor is functionally composed of four gas detectors, but three gas detectors covered with the same type of filter are housed in one filter to form two gas detectors as a whole. This is the case.

FIG. 6 is a diagram of a composite gas sensor according to another embodiment of the present invention, in which (a) is a gas detector of three elements (S11 + S11x).
+ S21) cross section, (b) is a 3-element gas detector (S11 + S1)
1x + S21) is a plan view, and (c) is a cross-sectional view of a single element gas detector S12x. 3-element gas detector (S11 + S11x + S21)
Are the gas detection element 11 and the gas detection element in the second embodiment.
11x and gas sensing element 12 base 3c with 6 pins
Each of the two is welded and covered with an activated carbon filter 21c. A heat shield 5 was provided between the elements so that each element was thermally independent.

The gas detector S12x of one element is a gas detector element.
11x is covered with a filter 22a of activated carbon carrying a noble metal catalyst. Gas detection element 11 (gas detection section S11) and gas detection element 12 in the filter 21c, which are methane detection pairs
(Gas detector S21) was incorporated in each bridge circuit, and the bridge output was examined in the same manner as in Example 1. FIG. 7 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example. 31M, 31
C, 31H and 31E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 7 it can be seen that this methane sensing pair is sensitive only to methane. Similarly, a gas detection element 11x in the activated carbon filter 21c, which is a CO / hydrogen detection pair.
(Gas detector S11x) and activated carbon filter 2 with precious metal catalyst support
The gas detection element 11x (gas detection unit S12x) in 2a was incorporated in a bridge circuit, and the bridge output was examined in the same manner as in Example 1. FIG. 8 is a graph of bridge output for CO, hydrogen sensing couple methane, CO, hydrogen and ethanol for this example. 32M, 32C, 32H and 32E are bridge outputs for methane, CO, hydrogen and ethanol.

It can be seen from FIG. 8 that this CO, hydrogen detection pair is sensitive only to CO and hydrogen. Therefore, the composite gas sensor, which uses the methane detection pair and the CO / hydrogen detection pair at the same time, can detect gas leakage and incomplete combustion separately. Furthermore, according to this configuration, the methane detection unit, the CO, and the hydrogen detection unit are housed in a total of two bases, so a space-saving effect can be obtained when the detector is mounted on the base. Example 4 This composite gas sensor is functionally composed of four gas detection parts, but three gas detection elements covered with the same kind of filter are put in one filter to form two gas detection parts as a whole. This is the case.

9A and 9B are views of a composite gas sensor according to another embodiment of the present invention. FIG. 9A is a sectional view of a gas detector S21x having one element, and FIG. 9B is a gas detector having three elements (S12 + S22 + S22x). Figure 3 (c) is a three-element gas detector (S12 + S22 + S22
It is a top view of (x). 3-element gas detector (S11 + S22 + S
22x) is a gas detection element 11, a gas detection element 12 and a gas detection element 12x in Example 2 which are welded to each two pieces of the base 3c having six pins and covered with the activated carbon filter 22c carrying a noble metal catalyst. It is a thing. A heat shield 5 was provided between the elements so that each element was thermally independent.

The one-element gas detector S21x is a gas detector element.
12x is covered with activated carbon filter 21a. The gas detection element 11 and the gas detection element 12 in the filter 22c, which are a methane detection pair, were respectively incorporated in the bridge circuit, and the bridge output was examined in the same manner as in Example 1. FIG. 10 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example. 41M, 41C,
41H and 41E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 10 it can be seen that this methane sensing pair is sensitive only to methane. Similarly, a gas detection element 12x in the activated carbon filter 21c, which is a CO / hydrogen detection pair.
Example 1 and the gas detection element 12x in the activated carbon filter 22a supporting a noble metal catalyst were respectively incorporated in the bridge circuit,
I examined the bridge output as well. FIG. 11 shows this embodiment
3 is a graph of bridge outputs for methane, CO, hydrogen and ethanol for CO, hydrogen sensing couple. 42M, 42C, 42H
And 42E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 11, it is understood that this CO / hydrogen detecting pair is sensitive only to CO / hydrogen. Therefore, the composite gas sensor, which uses the methane detection pair and the CO / hydrogen detection pair at the same time, can detect gas leakage and incomplete combustion separately. Furthermore, according to this configuration,
Since the CO and hydrogen detectors are housed in two bases as a whole, a space-saving effect can be obtained when mounted on the detector. Example 5 This composite gas sensor comprises four gas detectors. Figure 1
2 is a diagram of a composite gas sensor according to another embodiment of the present invention,
(A) is a cross-sectional view of the methane detection unit S1, (b) is a cross-sectional view of the gas detection unit S2 which is paired with it, (c) is a cross-sectional view of the CO detection unit S1x, (d) is a gas paired with this It is a cross-sectional view of a detection unit S13x.

Also in this embodiment, in order to balance the gas detection output, the same gas detection element as in Embodiment 2 was used.
Methane detector S1, paired gas detector S2 and CO detector S1x
Is a gas detector element 1 on pin 4 of the individual base 3a.
Only 1, 12 and 11x are welded and the wire mesh 20a is covered, not the filter.

The gas detecting element S13x, which is paired with the CO detecting element S1x, has the gas detecting element 11x welded to the pin 4 of the base 3a to form a wire mesh.
20a is covered, and an α-iron oxide filter 23a carrying a gold catalyst is further covered. The gas detection element 11 (gas detection section S1) and the gas detection element 12 (gas detection section S2), which are methane detection pairs, are incorporated in a bridge circuit, respectively, and the first embodiment is shown.
I examined the bridge output as well. FIG. 13 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example. 51M, 51C, 51H and 51E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 13, it can be seen that this methane detection pair is sensitive only to methane. Similarly, the gas detection element 11x (gas detection section S1x) and the gas detection element 11x (gas detection section S13x) in the activated carbon filter 23a, which are CO and hydrogen detection pairs, are incorporated in the bridge circuit, respectively, and the same as in the first embodiment. I checked the bridge output. FIG. 14 is a graph of bridge output for CO, hydrogen sensing couple methane, CO, hydrogen and ethanol for this example. 32M, 32C, 32H and 32
E is the bridge output for methane, CO, hydrogen and ethanol.

From FIG. 14, it can be seen that this CO / hydrogen detecting pair is sensitive only to CO and hydrogen. Therefore, the composite gas sensor, which uses the methane detection pair and the CO / hydrogen detection pair at the same time, can detect gas leakage and incomplete combustion separately. Example 6 This composite gas sensor is composed of four gas detectors, the methane detection pair is the same as that of Example 5, and the CO detection pair is different.

FIG. 15 shows the CO of another composite gas sensor of the present invention.
It is a figure of a detection pair, (a) sectional drawing of CO detection part S11x,
(B) It is sectional drawing of the gas detection part S113x which becomes a pair with this. Also in this example, in order to balance the gas detection output, the same gas detection element as in Example 2 was used. CO detector
S11x is the same as the gas detector S11x of the third embodiment. The gas detection unit S113x, which is paired with this, has the gas detection element 11x welded to the pin 4 of the base 3a, covered with the wire net 20a, and covered with the α-iron oxide filter 23a carrying a gold catalyst.
Furthermore, the activated carbon filter 21a is covered.

As the CO detection pair, the CO detection unit S11x and the paired gas detection unit S113x were incorporated in the bridge circuit, and the outputs for the respective gas components of methane, CO, hydrogen and ethanol were evaluated in the same manner as in Example 1. FIG. 16 is a graph of bridge outputs for CO sensing pair for methane, CO, hydrogen, and ethanol. 62M, 62C, 62H and 62E are methane, CO,
Bridge output for hydrogen and ethanol. FIG.
It turns out that it is sensitive only to CO.

Since the methane detection pair is the same as in Example 5,
By using the composite gas sensor including the four gas detection units of the present invention, gas leakage and incomplete combustion can be detected separately. Next, in order to evaluate the temporal stability of the bridge output of the CO detection pair of this example, the detection pair was incorporated into a bridge circuit and kept in an energized state in the atmosphere, and the gas detection element output was measured at regular intervals. FIG. 17 shows the CO of this example.
6 is a graph of stability over time of bridge output of a sensing pair. For comparison, FIG. 17 also shows the temporal stability of the CO detection pair coated with only the α-iron oxide filter supporting the gold catalyst of Example 5. The methane detection pair of Example 6 is curve 63, Example 5
The methane detection pair of is the curve 53.

From FIG. 17, the CO output of the CO detection pair of the fifth embodiment tends to slightly decrease, while
When an activated carbon filter is added like the CO detection pair
It can be seen that no reduction in CO output is observed. Example 5
The CO output of the CO detection pair decreases when the gas detection unit S113x
This is because the CO oxidation activity of the gold / iron oxide catalyst of the (substantially temperature compensating part) decreases with time, and a part of CO permeates inside the element part and oxidizes on the surface of the element.

The reason why the CO oxidation activity of the gold / iron oxide catalyst is lowered and the stability is improved when combined with the activated carbon filter is not known at present. As mentioned above,
By using the composite gas sensor of this embodiment, it is possible to obtain a composite detector capable of separately detecting gas leakage and incomplete combustion and having excellent long-term reliability. Example 7 This composite gas sensor is externally composed of two gas detection parts. A gas detection element 11 of a methane detection pair in Example 6;
12 can be covered with an activated carbon filter to obtain a methane sensing couple similar to that in Example 6. In this case, there are three gas detection elements that require only an activated carbon filter, and these are combined into one gas detection unit (S11 + S21 + S11x). Figure 1
FIG. 8 is a cross-sectional view of a three-element gas detector (S11 + S21 + S11x) which is a composite gas sensor according to another embodiment of the present invention. The gas detecting elements 11, 12, and 11x are welded to each two pieces of the base 3c having six pins, and are covered with the activated carbon filter 21c. As in Example 2, a heat shield plate was provided between the elements. The remaining gas detector S113x is the same as that of the sixth embodiment.

The gas detection element 11 (gas detection section S11) in the filter 21c and the gas detection element 12 (gas detection section S21) in the filter 22a, which are methane detection pairs, are incorporated in the bridge circuit, respectively, and the first embodiment is explained. Similarly, the bridge output was examined.
FIG. 19 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example. 71M, 71C, 71H and 71E are methane, CO, hydrogen,
Bridge output for ethanol.

From FIG. 19, it can be seen that this methane detection pair is sensitive only to methane. Similarly, the gas detection element 11x in the double filter of the CO detection pair, that is, the gas detection element 11x (gas detection section S11) in the activated carbon filter 21c, the activated carbon filter 21c, and the iron oxide filter 23a supporting the gold catalyst is used.
The (gas detector S113x) and the gas detector were incorporated in a bridge circuit, and the bridge output was examined in the same manner as in Example 1. FIG. 20 is a graph of bridge output for methane, CO, hydrogen and ethanol of the CO sensing pair of this example. 72M, 72C
, 72H and 72E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 20, it is understood that this CO / hydrogen detecting pair is sensitive only to CO. Therefore, the composite gas sensor that uses the methane detection pair and the CO detection pair at the same time can detect gas leakage and incomplete combustion separately. Furthermore, according to this configuration, the methane detector, the CO, and the hydrogen detector are housed in two bases as a whole,
When mounted on a detector, a space saving effect can be obtained. Example 8 This composite gas sensor is externally composed of two gas detection parts. The gas detection elements 11 and 12 of the methane detection pair and the gas detection element 12x of the CO detection pair are covered with an iron oxide filter and an activated carbon filter, and the other gas detection elements 12x of the CO detection pair are covered with only an activated carbon filter. A composite gas sensor having the same function as 6 was obtained. In this case, there are three gas detection elements that require an iron oxide filter and an activated carbon filter, and these are collectively used as one gas detection unit (S113 + S213 + S213x). Figure 21
Is a composite gas sensor of another embodiment of the present invention,
(A) is a cross-sectional view of a CO detection unit (S21x), and (b) is a cross-sectional view of a three-element gas detection unit (S113t + S213 + S213x).
Gas detection element 11, 12, 12x, base 3c with this pin
Are welded to each two and covered with an iron oxide filter 23c and an activated carbon filter 21c. As in Example 2, a heat shield plate was provided between the elements. The remaining gas detection unit S21x is a gas detection element 12x covered with an activated carbon filter 21a.

The gas detection element 11 (gas detection section S113) and the gas detection element 12 (gas detection section S213) in the double filter, which are methane detection pairs, are incorporated in the bridge circuit,
The bridge output was examined in the same manner as in Example 1. FIG. 22 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example. 81M, 81C
, 81H and 81E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 22, it can be seen that this methane detection pair is sensitive only to methane. Similarly, the gas detection element 12x (gas detection section S21x) in the activated carbon filter 21c and the gas detection element 12x (gas detection section S213x) in the double filter, which are CO detection pairs, are incorporated in the bridge circuit, respectively, and the embodiment is shown. The bridge output was examined as in 1. FIG. 23 is a graph of bridge output for methane, CO, hydrogen and ethanol of the CO sensing pair of this example. 82M, 82C, 82H
And 82E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 23, it is understood that this CO / hydrogen detecting pair is sensitive only to CO. Therefore, the composite gas sensor that uses the methane detection pair and the CO detection pair at the same time can detect gas leakage and incomplete combustion separately. Furthermore, according to this configuration, the methane detector, the CO, and the hydrogen detector are housed in two bases as a whole,
When mounted on a detector, a space saving effect can be obtained. Example 9 This composite gas sensor consists of two gas detectors. Figure 2
4 is a diagram of a gas detector of two elements of another embodiment of the present invention, (a) is a gas detector with an activated carbon filter (S11 +
(S11x) cross section, (b) cross section of the gas detector (S213 + S213x) with iron oxide filter and activated carbon filter, (c)
Are plan views of S11 + S11x and (d) a plan view of S213 + S213x. In this example, a composite gas sensor having a function similar to that of Example 6 was obtained.

In this case, there are two gas detection elements that require only the activated carbon filter, and these are collectively used as one gas detection section (S11 + S11x), and two gas detection elements that require the iron oxide filter and the activated carbon filter are provided. Therefore, these are collectively set as one gas detection unit (S213 + S113x). The gas detecting elements 11 and 11x are welded to each two pieces of the base 3b having four pins and covered with the activated carbon filter 21b. As in Example 2, a heat shield plate was provided between the elements. Similarly, the gas detection elements 11 and 11x were covered with the iron oxide filter 23b and the activated carbon filter 21b.

The gas detection element 11x (gas detection section S113) and the gas detection element 12 (gas detection section S213) in the double filter, which is a methane detection pair, are incorporated in the bridge circuit,
The bridge output was examined in the same manner as in Example 1. FIG. 25 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example. 91M, 91C
, 91H and 91E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 25, this methane detection pair is
It turns out that it is sensitive only to CO. However, the CO output of the methane detection pair is extremely small compared to the methane output,
For example, for the coexisting concentrations of 2 gases that can actually occur,
For example, the relative output between the methane output of 3000 ppm and the CO output of 500 ppm is 1/15, and even if CO coexists at the time of gas leakage, the accuracy of methane detection is hardly reduced.

Similarly, an activated carbon filter which is a CO detection pair
The gas detection element 11x (gas detection section S11x) in 21c and the gas detection element 11x (gas detection section S113x) in the double filter were respectively incorporated in a bridge circuit, and the bridge output was examined in the same manner as in Example 1. FIG. 26 is a graph of bridge output for methane, CO, hydrogen and ethanol of the CO sensing pair of this example. 92M, 92C, 92H and 92E are bridge outputs for methane, CO, hydrogen and ethanol.

From FIG. 26, it can be seen that this CO / hydrogen detecting pair is sensitive only to CO. Therefore, the composite gas sensor that uses the methane detection pair and the CO detection pair at the same time can detect gas leakage and incomplete combustion separately. Furthermore, according to this configuration, the methane detection unit, the CO, and the hydrogen detection unit are housed in two bases as a whole,
When mounted on a detector, a space saving effect can be obtained.

[0066]

The composite gas sensor of the present invention is a first gas detection element (E1, hereinafter gas detection element) in which a metal oxide carrier carrying an oxidation catalyst mainly of palladium is fixed to a resistance temperature detector. Of the second gas detection element (E2) in which the metal oxide carrier carrying the platinum-based oxidation catalyst is fixed to the resistance temperature detector. In any one element, a first filter (F1) made of activated carbon, a second filter (F2) made of activated carbon carrying a noble metal catalyst, and a third filter made of iron oxide carrying gold
Any one of the filters (F3) of (1) to (3) is composed of a predetermined combination of 2 to 4 of the gas detection section covered, and in any combination, the gas detection device incorporating these in the bridge circuit It is possible to continuously detect methane generated during leakage and CO generated during incomplete combustion or a mixed gas of CO and hydrogen. In addition, since it has no sensitivity to ethanol generated from the sake liquor or mirin during cooking, it is extremely reliable without the risk of false alarms even when used in the actual field.

Further, it is possible to obtain a highly reliable gas leak / incomplete combustion combined type detector without sensitization of alarm concentration due to water vapor in gas unlike in the case of using a semiconductor gas sensor. it can. The effects of each combination will be described below. The combination gas detector and filter of the first composite gas sensor is E1F1 and E2F2 or E1F2 and E2F1, so a pair of sensors can detect gas leakage and incomplete combustion at the same time, and the configuration is simple and inexpensive. A gas leak / incomplete combustion simultaneous detection type detector can be obtained.

The second composite gas sensor is functionally composed of four gas detectors, the combination of which is the first group, E1.
And E2, E1F1 and E2F1, E1F2 and E2F2, E1F3 and 2F3, or 1F
One set of 1F3 and 2F1F3 and a third group consisting of the other two gas detectors, E1F1 and E1F2, or E2F1
It consists of one pair of E2F2. The bridge outputs of the first group can have bridge outputs for methane only and the bridge outputs of the third group can have bridge outputs for CO and hydrogen,
It is possible to obtain a gas detection device that can distinguish between methane and CO and hydrogen, that is, gas leakage and incomplete combustion.

The third composite gas sensor is functionally composed of four gas detectors, the combination of which is the first group,
E1 and E2, E1F1 and E2F1, E1F2 and E2F2, E1F3 and 2F3, or
A fourth group consisting of one pair of 1F1F3 and 2F1F3 and two other gas detectors, E1 and E1F3, E2 and E2F3, E1
It consists of either one of F1 and E1F1F3, or E2F1 and E2F1F3.

The bridge outputs of the first group can have bridge outputs for methane only and the bridge outputs of the fourth group can have bridge outputs for CO only, so the third composite The gas sensor can provide a gas detection device that can distinguish between methane and CO, that is, gas leakage and incomplete combustion. It becomes possible to identify.

That is, the incomplete combustion detection unit is sensitive only to CO in gas and is not sensitive to any other component. The concentration ratio of CO and hydrogen in incomplete combustion gas is generally 2 /
Although it is supposed to be 1, the ratio actually varies depending on the combustion state. The third compound gas sensor is
Despite the CO and hydrogen concentration fluctuations, it is sensitive only to the concentration of CO, which is a toxic component in incomplete combustion gas, and is extremely reliable.

The fourth composite gas sensor is functionally composed of four gas detectors, and is externally composed of two gas detectors.
A second group of two gas detectors, E1 and E2F3,
One set of any one of E2 and E1F3, E1F1 and E2F1F3, or E2F1 and E1F1F3 and one set of any of the fourth groups consisting of two gas detection units. Similar to the above, the second group can have a bridge output only for methane and CO, but the output for CO is less than the output for methane, and the fourth group has a bridge output for CO only. Since it can have, a 4th composite gas sensor can obtain the gas detection apparatus which can distinguish methane and CO, ie, gas leak and incomplete combustion. Also, since the outer shape is stored in two bases,
It takes up little space in the detector and is extremely practical.

The third group or the fourth group
Since the resistance value of the resistance temperature detector of the gas detection element of the group is set to 3 to 10 times the resistance value of the resistance temperature detector of the gas detection element of the first group and the second group,
The bridge output is about the same for CO, which has a detection concentration that is about an order of magnitude lower than that for methane, and the comparator for detecting the bridge output level can have the same function for both.

[Brief description of drawings]

FIG. 1 is a diagram of a composite gas sensor according to one embodiment of the present invention,
(A) is a cross-sectional view of the gas detection unit S11, (b) is a cross-sectional view of the paired detection unit S22

FIG. 2 is a graph of a bridge output of a composite gas sensor according to an embodiment of the present invention.

FIG. 3 is a diagram of a composite gas sensor according to another embodiment of the present invention,
(A) is a cross-sectional view of the methane detection unit S1, (b) is a cross-sectional view of the gas detection unit S2 to be paired with it, (c) is a cross-sectional view of the CO and hydrogen detection unit S21x, (d) this Gas detector S22x
Cross section of

[Figure 4] Graph of bridge output for methane, CO, hydrogen, and ethanol of methane detection pair

[Fig. 5] Graph of bridge output for methane, CO, hydrogen, and ethanol of CO, hydrogen detection pair

6A and 6B are views of a composite gas sensor according to another embodiment of the present invention, in which FIG. 6A is a sectional view of a three-element gas detector (S11 + S11x + S21), and FIG. 6B is a three-element gas detector (S11 + S11x + S21). Plan view, (c) is a cross-sectional view of the single-element gas detector S12x

FIG. 7 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example.

FIG. 8 is a graph of CO, hydrogen sensing couple bridge outputs for methane, CO, hydrogen and ethanol for this example.

9A and 9B are views of a composite gas sensor according to another embodiment of the present invention, FIG. 9A is a cross-sectional view of a single-element gas detector S21x, and FIG.
Is a cross-sectional view of a 3-element gas detector (S12 + S22 + S22x),
(C) Plan view of the 3-element gas detector (S12 + S22 + S22x)

FIG. 10 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example.

FIG. 11: CO of this embodiment, methane of a hydrogen detection pair, CO,
Graph of bridge output for hydrogen and ethanol

12A and 12B are views of a composite gas sensor according to another embodiment of the present invention, in which FIG. 12A is a cross-sectional view of a methane detection unit S1, FIG. 12B is a cross-sectional view of a gas detection unit S2 as a pair therewith, and FIG. ) Is the CO detector S1
x sectional view, (d) sectional view of the gas detector S13x, which is the pair with this

FIG. 13 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example.

FIG. 14: CO of this embodiment, methane of a hydrogen detection pair, CO,
Bridge output for hydrogen and ethanol

FIG. 15 is a diagram of another composite gas sensor of the present invention,
(A) Cross-sectional view of the CO detection unit S11x, (b) Cross-sectional view of the gas detection unit S113x paired therewith

FIG. 16: Graph of bridge output for methane, CO, hydrogen, and ethanol of CO detection pair

FIG. 17 is a graph of stability over time of bridge output of CO detection pair in this example.

FIG. 18 is a cross-sectional view of a three-element gas detector (S11 + S21 + S11x) that is a composite gas sensor according to another embodiment of the present invention.

FIG. 19 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example.

FIG. 20 is a graph of bridge output for methane, CO, hydrogen and ethanol of the CO sensing pair of this example.

FIG. 21 is a composite gas sensor according to another embodiment of the present invention, (a) is a sectional view of a CO detection section (S21x), and (b) is a sectional view of a gas detection section (S113 + S213 + 213x) of the element.

FIG. 22 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example.

FIG. 23 is a graph of bridge output for methane, CO, hydrogen and ethanol for the CO sensing pair of this example.

FIG. 24 is a diagram of a gas detector of two elements of another embodiment of the present invention, (a) is a gas detector with an activated carbon filter (S
11 + S11x) cross section, (b) cross section of gas detector (S213 + S213x) with iron oxide filter and activated carbon filter,
(C) Plan view of S11 + S11x, (d) Plan view of S213 + S213x

FIG. 25 is a graph of bridge output for methane, CO, hydrogen and ethanol of the methane sensing pair of this example.

FIG. 26 is a graph of bridge output for methane, CO, hydrogen and ethanol of the CO sensing pair of this example.

[Explanation of symbols]

11 Pd-supported gas detection element 11x Pd carrying gas detection element 12 Pt-supported gas detection element 12x Pt-supported gas detection element 20a wire mesh 20b wire mesh 20c wire mesh 21k cap 21a Activated carbon filter 21b Activated carbon filter 21c Activated carbon filter 22a Noble metal catalyst-supporting activated carbon filter 22b Noble metal catalyst supported activated carbon filter 22c Noble metal catalyst supported activated carbon filter 23a Iron oxide filter with gold catalyst 23b Iron catalyst supported iron oxide filter 23c Iron catalyst supported iron oxide filter 3a base 3b base 3c base 4 pin Sij gas detector, i (= 1,2): Corresponding to the type of gas detector j (= 1,2,3): Corresponds to the filter type Sijk gas detector, i (= 1,2): Corresponding to the type of gas detector j, k (= 1,2,3): Corresponds to the filter type

Claims (8)

(57) [Claims] 1. A first gas detection element in which a metal oxide carrier carrying an oxidation catalyst is fixed to a resistance temperature detector, and the oxidation catalyst is mainly palladium, or the same as the first gas detection element. Either the first filter made of activated carbon or the second filter made of activated carbon carrying a noble metal catalyst is used for one of the gas detection elements of the second gas detection element in which the oxidation catalyst is mainly platinum. In a composite gas sensor in which any two gas detection parts of the gas detection parts covered by the filter are combined, the combination of the gas detection parts is such that the first gas detection element is covered by the first filter. A gas detecting part formed by covering the second gas detecting element and the second gas detecting element with the second filter, or the first gas detecting element covered with the second filter. Composite gas sensor, characterized in that that gas detector and the gas detecting portion in which the first filter to the second gas sensing element are thus covered, it is. 2. A first gas detection element in which a metal oxide carrier carrying an oxidation catalyst is fixed to a resistance temperature detector, and the oxidation catalyst is mainly palladium, or the same as the first gas detection element. The oxidation catalyst has a first filter made of activated carbon, a second filter made of activated carbon carrying a noble metal catalyst, or a gold detection catalyst in any of the second gas detection elements mainly containing platinum. A composite gas sensor in which four gas detection units are combined with any one of the third filters made of iron oxide carrying Fe, or the gas detection unit is covered with no filter. The combination of the gas detectors is a first group consisting of a set of the following two gas detectors, respectively, the gas detector consisting of the first gas detector not covered by the filter and the filter. Gas detector consisting of the not covered second gas sensing element, wherein the first of said the gas sensing element and the first filter is a gas detecting part formed by overlaid second
Wherein the first gas detector which the filter is provided over the gas sensing element, the said first gas detector for the second filter to the gas sensing element are thus covered second gas sensing element A gas detecting section covered by a second filter, a gas detecting section formed by covering the first gas detecting element with the third filter, and a third filter covering the second gas detecting element. Or a gas detecting section in which the first filter and the third filter are covered on the first gas detecting element, and the first filter on the second gas detecting element. A gas detector covered with the third filter, and a third group consisting of a set of the following two gas detectors.
A gas detecting section in which the first filter is covered with the first gas detecting element, and a gas detecting section in which the second filter is covered with the first gas detecting element, or the second gas Any one of a gas detection section in which a detection element is covered with the first filter and a gas detection section in which the second gas detection element is covered with the second filter
A composite gas sensor comprising: 3. A first gas detection element in which a metal oxide carrier carrying an oxidation catalyst is adhered to a resistance temperature detector, and the oxidation catalyst is mainly palladium, or the same as the first gas detection element. The oxidation catalyst has a first filter made of activated carbon, a second filter made of activated carbon carrying a noble metal catalyst, or a gold filter in any one of the second gas detection elements whose main component is platinum. A composite gas sensor in which four gas detection units are combined with any one of the third filters made of iron oxide carrying Fe, or the gas detection unit is covered with no filter. The combination of the gas detectors is a first group consisting of the following two sets of gas detectors, the gas detector consisting of the first gas detector element not covered by the filter and the filter. Gas detector consisting of the not covered second gas sensing element, wherein the first of said the gas sensing element and the first filter is a gas detecting part formed by overlaid second
Wherein the first gas detector which the filter is provided over the gas sensing element, the said first gas detector for the second filter to the gas sensing element are thus covered second gas sensing element A gas detecting section covered by a second filter, a gas detecting section formed by covering the first gas detecting element with the third filter, and a third filter covering the second gas detecting element. Or a gas detection section in which the first filter and the third filter are covered with the first gas detection element, and the first filter in the second gas detection element. A gas detecting section covered with the third filter, and a fourth group consisting of a set of the following two gas detecting sections,
A gas detection unit that is not covered by a filter and that is composed of the first gas detection element, a gas detection unit that is formed by covering the first gas detection device by the third filter, and a second gas that is not covered by the filter. A gas detection unit including a detection element, a gas detection unit including the second gas detection element covered with the third filter, and the first gas detection element including the first gas detection element.
Of the gas detecting section and the first gas detecting element covered with the first filter and the third gas filter, and the first gas detecting section and the second gas detecting element covered with the first filter and the third filter. And a gas detection section in which the second gas detection element is covered with the first filter and the third filter. Characteristic compound gas sensor. 4. A first gas detecting element having a metal oxide carrier carrying an oxidation catalyst fixed to a resistance temperature detector, the oxidation catalyst being mainly palladium, or the same as the first gas detecting element. The oxidation catalyst is a platinum-based second gas detection element, and one of the gas detection elements is a first filter made of activated carbon, a second filter made of activated carbon carrying a noble metal catalyst, or gold. A composite gas sensor in which any of the third filters made of iron oxide carrying C is covered with or is not covered with any of the four gas detection units. , The gas detectors are combined in a second group consisting of the following two gas detectors each, and the gas detector consisting of the first gas detector not covered with a filter and the first gas detector. A gas detecting section in which the second gas detecting element is covered with the third filter; a gas detecting section including the second gas detecting element in which the filter is not covered; and the third gas detecting element in the first gas detecting element. A gas detecting section covered with a filter; a gas detecting section formed by covering the first gas detecting element with the first filter; and a second gas detecting element including the first filter and the third gas detecting section. A gas detection part covered with a filter, a gas detection part covered with the first filter over the second gas detection element, and the first filter and the third gas detection element over the first gas detection element. A gas detecting part covered with a filter, a fourth group consisting of a set of the following two gas detecting parts, and a gas consisting of the first gas detecting element not covered with a filter Detector and the above The gas detecting section in which the first gas detecting element is covered with the third filter, the gas detecting section including the second gas detecting element in which the filter is not covered, and the second gas detecting element are connected to the third gas detecting section. A gas detection unit in which a filter is covered, a gas detection unit in which the first filter is covered on the first gas detection element, and the first filter and the third gas detection unit on the first gas detection element. The gas detection part formed by covering the filter and the gas detection part formed by covering the second gas detection element by the first filter, and the first part formed by the second gas detection element
And a gas detection part covered with the third filter, and a gas detector part. In the composite gas sensor according to any one of the claims 5] claims 2 to 4, the gas sensing element of the same type filter is covered, the composite gas sensor characterized in that it is housed within the same filter. 6. The composite gas sensor according to claim 2 , wherein the resistance value of the resistance temperature detector of the gas detection element of the third group is the resistance value of the resistance temperature detector of the gas detection element of the first group. 3 to 10 times the composite gas sensor. 7. The composite gas sensor according to claim 3.
The temperature sensing resistor of the gas detection element of the fourth group
The resistance value is the temperature measuring resistance of the gas detection element of the first group.
A compound characterized by being 3 to 10 times the resistance of the body
Gas sensor. 8. The composite gas sensor according to claim 4.
The temperature sensing resistor of the gas detection element of the fourth group
The resistance value is the temperature measuring resistance of the gas detection element of the second group.
A compound characterized by being 3 to 10 times the resistance of the body
Gas sensor.