JPS63250556A - Gaseous component detecting element - Google Patents

Abstract

PURPOSE:To permit detection of the amt. of NOX in an NOX atmosphere in accordance with a difference in the detected values in a 1st NOX detecting element part provided with a catalyst having a reduction effect to NOX and the 2nd NOX detecting element part provided with a catalyst having the reduction effect on NOX smaller than the effect of the 1st element part by providing the above-mentioned two detecting element parts. CONSTITUTION:The detecting element 21 is formed by using, for example, pellet type titania as the metallic oxide of which the resistance value changes with the gaseous components in the atmosphere. The one pellet constituting the 1st element part 22 is so constituted as to have the reduction effect on the NOX and the other pellet constituting the 2nd element part 23 is constituted as to have substantially no reduction effect on the NOX or to have no reduction effect. A method of using element part lead wires 22a, 22b, 23a, 23b, impressing a constant voltage between the lead wires 22a and 23a and measuring the potential of the lead wire 22b (23b) is adopted to take out electrodes. The detection of the amt. of the NOX even in the high-temp. atmosphere is thereby permitted and the dependency of the output on temp. is substantially eliminated.

Description

[Detailed description of the invention]

OBJECTS OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas component detection element used, for example, to detect the amount of NOx in combustion exhaust gas discharged from an automobile combustion engine. (Prior Art) Conventionally, a gas component detection element used for detecting the amount of NOx in the atmosphere is 1, for example, 5AE80053.
There is one that was enacted in 7. This gas component detection element has, for example, 41% tin oxide (Sn02), which is a metal oxide semiconductor, on a steatite substrate.
It has a structure formed by M, and as shown in Fig. 17, N in the combustion exhaust gas is
It has a characteristic that the resistance of the gas component detection element changes as shown in FIG. 17 when the O, NOx, and No2g levels (measured by chemiluminescence analysis) change.
By detecting this change in resistance value, the ratio of air to fuel (A/F) is determined.
It is designed so that it can be measured. (Problems to be Solved by the Invention) However, since the preferred operating temperature of such conventional gas component detection elements is about 250°C, the combustion When used to detect NOxi in exhaust gas, there was a problem in that heat resistance was considerably insufficient. In addition, gas component detection elements for detecting NOx gas have been developed, but none are suitable for practical use, especially for detecting the amount of NOx contained in the combustion exhaust gas of automobile combustion engines. Although fuel ratio detection elements with various structures have been developed, the reality is that no air-fuel ratio sensor that can specifically measure the amount of NOx has been found. (Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems and actual circumstances, and is particularly suitable for detecting the amount of NOx in combustion exhaust gas discharged from an automobile combustion engine. The object is to provide a gas component detection element. [Structure of the Invention] (Means for Solving the Problems) A gas component detection element according to the present invention includes a first NOx detection element section including a catalyst having a reducing action on NOx;
A second NOx detection element section is provided which has a smaller amount of catalyst than the first element section, and has a reducing action on NOx.
The present invention is characterized in that the amount of NOx in the atmosphere is detected based on the difference between the detection values in both the element parts in the atmosphere. In an embodiment of the present invention, the NOx is reduced. The element portion having an action may include a three-way catalyst component, and the element portion having no reducing action on NOx may include an oxidation catalyst component. The gas component detection element in one embodiment of the present invention includes at least two gas component detection element sections made of metal oxide whose resistance value changes depending on the gas component in the atmosphere, and one gas component detection element section is configured. or (and) providing a catalyst layer containing a three-way catalyst component on the surface of the metal oxide constituting one of the gas component detection element portions, and An oxidation catalyst component is contained in the metal oxide constituting the gas component detection element section, or (and) an oxidation catalyst component is contained in the surface of the metal oxide constituting the other gas component detection element section. The structure may include a catalyst layer. Further, in another embodiment of the present invention, a solid electrolyte whose oxygen ion conductivity changes depending on gas components in the atmosphere is used as a gas component detection element. providing at least two electrodes on the surface of the solid electrolyte,
A three-way catalyst component is contained in the one electrode, or (
and) on the surface of said one electrode. A catalyst layer containing a three-way catalyst component is provided, the other electrode contains an oxidation catalyst component, or (and) a catalyst layer containing an oxidation catalyst component is provided on the surface of the other electrode. It can be of any configuration. Furthermore, as in the embodiment described above, a gas component detection element according to still another embodiment of the present invention uses a solid electrolyte whose oxygen ion conductivity changes depending on the gas component in the atmosphere, and has a coating on the surface of the solid electrolyte. at least two measurement electrodes exposed to the measurement atmosphere and a reference electrode in contact with the atmosphere, one of the measurement electrodes containing a three-way catalyst component, or (and) a surface of the one electrode. A catalyst layer containing a three-way catalyst component is provided,
The other of the measurement electrodes may contain an oxidation catalyst component, or (and) a catalyst layer containing an oxidation catalyst component may be provided on the surface of the other electrode. , (Example 1) FIGS. 1 to 6 are diagrams showing a first example of the gas component detection element according to the present invention, FIG. 1 is an overall view of the gas component detection element, and FIG. 2 ( a) and (b) are exploded views during manufacturing. The gas component detection element 1 shown in the figure includes a first element part 2 having a reducing effect on NOx and a second element part 3 having no reducing effect on NOx, and the gas component detecting element 1 shown in FIG. The configuration is such that the amount of NOx in the atmosphere is converted into a voltage output and detected based on the difference between the detected values in the element sections 2 and 3. The procedure for manufacturing the gas component detection element 1 having such a configuration will be further explained below. As shown in FIG. 2(a), three through holes 5a are formed in one substrate material 4a made of alumina green sheet or the like.
, 5b, 5c are formed, and a heater 6 and element leads 7a, 7 are formed on this substrate material 4a using platinum paste.
b and 7c are formed by screen printing. Platinum (pt) is added between 5 and 7b of one element part between 7a and 7b.
The unfired first element portion (2) is formed using a titania (T i 02 ) paste to which rhodium (Rh) is added in an amount of 15 wt% and 0.5 to 5 wt%. Moreover, between the other element part leads 7b and 7C, an unfired second element part (3) is formed using titania paste to which 5 to 15 wt% of platinum and 0 to 5 wt% of palladium (Pd) are added. . Further, on the back side of the substrate material 4a, an electrode extraction terminal 8a,
8b and 8c are formed using platinum paste, and a through hole 5a is formed. By filling platinum paste in 5b and 5c, each electrode extraction terminal 8a, 8b, 8c and heater terminal 6a
, 6b and the center element lead 7 can be electrically connected after firing. Further, as shown in FIG. 2(b), a through hole 1 is formed in the other substrate material 4b made of an alumina green sheet or the like.
0a, 10b, and terminal 11a. 11b and an opening 12 are formed, and the other substrate material 4b and the one substrate material 4a are laminated by thermocompression bonding. And through hole 10a. By filling platinum paste in 10b, the device leads 7a and 7c on both sides and the terminal 11a. 11b so as to be electrically connected to each other after firing, and this bonded body was fired in the atmosphere at 1400° C. for 2 hours to obtain the gas component detection element 1. In this gas component detection element 1, the first element part 2 is made of titania, which is a metal oxide whose resistance value changes depending on the gas component in the atmosphere, and platinum and rhodium are contained in the titania as three-way catalyst components. Because it contains
It has a reducing effect on NOx. The second element part 3 is also made of titania, and contains platinum or platinum and palladium as an oxidation catalyst component in the titania, so that it has a higher nitrogen content than the first element part 2.
It has no reducing effect on Ox. It should be noted that the production of the gas component detection element 1 is not limited to the above-mentioned materials and processes; it goes without saying that conventionally known materials and processes can be used. In the gas component detection element 1 shown in FIG.
Connect the heater power supply 13 between the terminals 8a and ac, and connect the terminal 1
A constant voltage power supply 14 is connected between terminals 1a and 11b, and a voltmeter (or comparator, etc.) 15 is connected between terminals 8b and llb to detect gas components. An equivalent circuit is shown. Therefore, the heater 6 is energized to maintain the element temperature at 600°C, and the gas component detection element 1 is exposed to the exhaust gas of the internal combustion engine, and the air-fuel ratio of the resistance value of the first element part 2 and the second element part 3 is determined. The results of investigating the dependence are shown in FIG. At this time, the NOx amount was kept constant at 1500 ppm, the engine operating conditions were 2000 ppm, and the torque was 4.5 kg*
It is m. The resistance of the first element part 2 appears between the terminals 11a and ab, and is caused by the rhodium W contained in titania, which is a three-way catalyst component.
Since the AI causes a reaction of 2NOX-4-N2+x02 to decompose NOx, the point of sudden resistance change coincides with the stoichiometric air-fuel ratio as shown in FIG. 4, regardless of the amount of NOx. On the other hand, the resistance of the second element section 3 appears between the terminals 8b and llb and does not have a reducing effect on NOx, so the sudden resistance change point is caused by the presence of NOx in the theoretical void as shown in FIG. The fuel ratio shifts to the lean side. Moreover, the more NOx there is, the more the position shifts. Therefore, when electrical connections are made as shown in FIGS. 1 and 3, a gas component detection element 1 as shown in FIG.
The output characteristics are obtained, and the relationship between the magnitude of the output and the amount of NOx is shown in FIG. Therefore, the amount of NOx can be detected from Fig. 6, and it is possible to detect the amount of NOx even in a high-temperature atmosphere such as the exhaust gas of an automobile internal combustion engine. Since the element parts 2 and 3 are combined, the output has almost no temperature dependence. (Example 2) The seventh factor is a diagram showing a second example of the gas component detection element according to the present invention. The gas component detection element 21 shown in the figure uses pellet-type titania as a metal oxide whose resistance value changes depending on the gas component in the atmosphere. It is impregnated with platinum and rhodium to have a reducing effect on NOx.
The other titania pellet constituting the second element portion 23 is impregnated with platinum so that it has little or no reducing effect on NOx. In this case, the electrodes are taken out through the element lead wires 22a embedded in each pellet. 22b, 23a, 23b, lead wires 22a and 23
N0xi in the atmosphere can be removed by applying a constant voltage between a and measuring the potential of the lead wire 22b (23b), that is, by adopting the same electrical connection as shown in FIGS. 1 and 3. It is possible to detect the amount of NOx even in a high-temperature atmosphere such as the exhaust gas of an automobile internal combustion engine, and also because the element parts 22 and 23 having similar resistance-temperature dependence are combined. , the output has almost no temperature dependence. The gas component detection elements according to the first and second embodiments described above can also be used as air-fuel ratio control sensors for automobile internal combustion engines. In that case, the air-fuel ratio is controlled by the first element section 2.22 made of titania containing a three-way catalyst component, and at the same time, the first element section 2.22 and the first element section 2.22 made of titania containing an oxidation catalyst component perform air-fuel ratio control. There is an advantage that the amount of NOx can be detected from the difference in resistance value between the second element section 3.23 and the second element section 3.23. (Embodiment 3) FIGS. 8 to 11 are diagrams showing a third embodiment of the gas component detection element according to the present invention. This gas component detection element 31 uses a solid electrolyte 32 whose oxygen ion conductivity changes depending on the gas components in the atmosphere, and has electrodes 33 and 34 provided on both surfaces of the solid electrolyte 32, and a solid state with one electrode 34 provided thereon. A heater 36 is provided on the surface of the electrolyte 32 via an insulating layer 35, an insulating layer 37 is provided on the surface of the heater 36, and both electrodes 33, 34 . A porous spinel layer 38 is coated on the surfaces of the insulating layer 37 and the solid electrolyte 32, and the surface of the spinel layer 38 in the portion where the electrode 33 is provided is made of a porous catalyst layer containing a three-way catalyst component, A first element portion 42 having a reducing effect on NOx is provided, and the surface of the spinel layer 38 in the area where the electrode 34 is provided is made of a porous catalyst layer containing an oxidation catalyst component, and has a reducing effect on NOx. This is caused by the difference in oxygen partial pressure on the surface of the solid electrolyte 32, which is caused by the difference in the actions of the two element parts 42 and 43 in the NOx atmosphere. The structure is such that NOx in the atmosphere is detected by measuring the electromotive force generated. The procedure for manufacturing the gas component detection element 31 having such a structure will be further explained below. First, a pair of electrodes 33 and 34 are formed by screen printing using platinum paste on both sides of a green sheet of an oxygen ion conductive solid electrolyte 32 made of yttoria-stabilized zirconia. An insulating layer 35 is formed on at least one surface (one surface in the illustrated example) using an insulating paste containing a mixture of alumina and zirconia, and a heater 36 is formed thereon using a platinum paste. An insulating layer 37 is formed thereon using the insulating paste.
After forming, it is fired in the atmosphere at 1400°C for 2 hours. Next, spinel (MgO-A1203) was added to the fired body.
The porous spinel layer 38 is formed by plasma spraying. This spinel layer 38 does not necessarily need to be formed, but in order to protect the electrodes 33 and 34,
and each element part 42 consisting of electrodes 33, 34 and a catalyst layer.
, 43, it is more preferable to provide it in order to maintain a strong bond between the two. Furthermore, platinum (Pt) was added to γ-Ai2o, δ-A1203, or a mixture thereof.
．． 1 to 2 wt% and 0.05 to 1.0 rhodium (Rh)
The powder impregnated with .gamma.-AM, 0.0 wt. Alternatively, platinum (p
t) at 0.1 to 2 wt%, or platinum (Pt) at 0.1 to 2 wt%.
1 to 2 wt% and 0.1 to 1 wt of palladium (P d)
%≧ is made into a slurry, and after forming the second element part 43 consisting of a catalyst layer containing the oxidation catalyst by a spray method, it is baked in the atmosphere at 600°C for 30 minutes to form a gas component detection element. Get 31. It goes without saying that the manufacturing of the gas component detection element 31 is not limited to the materials and processes described above, and that conventionally known materials and processes can be used. In the gas component detection element 31 shown in FIG.
44 is connected, and a heater power source 45 is connected to both ends of the heater 36 to detect the amount of NOx. Next, the operation of the gas component detection element 31 having the above configuration will be explained. With the gas component detection element 31 electrically connected as shown in FIG. The output of the gas component detection element 31 was examined by exposing it to the inside. The results were as shown in FIG. The output of the gas component detection element 31 at this time is generated by the difference between the oxygen partial pressure PO2 (33) near the electrode 33 and the oxygen partial pressure PO2 (34) near the electrode 34,
The output is expressed by the following equation. Also, at this time, the NOx amount was kept constant at 1500 ppm, the engine operating conditions were 2000 rpm, and 4.
5 kg-m. . The reason why the output characteristics shown in FIG. 9 can be obtained is as follows. The oxygen partial pressure PO2 (34) in the vicinity of the electrode 34 covered by the second element portion 43 consisting of a catalyst layer containing an oxidation catalyst component containing platinum or platinum and palladium is equal to the first
As shown in Figure 0. Due to the presence of NOx, the point of sudden change in oxygen partial pressure shifts to the lean side from the stoichiometric air-fuel ratio. Further, the first element portion 42 includes a catalyst layer containing a three-way catalyst component to which platinum and rhodium are added.
Oxygen partial pressure po2 near the electrode 33 covered by
33) is 2NOx4N2 + due to the action of rhodium.
Since NOx is decomposed by the XO2c7) reaction, the point of sudden change in oxygen partial pressure coincides with the stoichiometric air-fuel ratio, regardless of the amount of NOx. Also, as the amount of NOx is reduced, PO2 (3
4) The curve moves to the left and approaches the stoichiometric air-fuel ratio. Therefore, the output of the gas component detection element 31 shown in FIG. 9 depends on the amount of NOx, and the output of the gas component detection element 31 and N0
The relationship with xi is shown in Figure 11, and this 11th
The amount of NOx can be detected from the characteristics shown in the figure, and NOx can be detected even in high-temperature atmospheres such as the exhaust gas of automobile internal combustion engines.
x amount can be detected, and since the electrodes 33.34 are covered with the element portions 42.43 made of catalyst layers, it is possible to reduce the amount of deterioration, and the
By providing an alumina layer made of 3 wδ-A 203 or a mixture thereof, the activity of both catalyst layers can be maintained for a long period of time. This further improves durability. (Embodiment 4) FIG. 12 is a diagram showing an i4 embodiment of the gas component detection element according to the present invention. The gas component detection element 41 shown in the figure has a built-in heater 36 covered with an insulating layer 37 inside an oxygen ion conductive solid electrolyte 32, and electrodes 33 and 34 are placed on the same surface of the solid electrolyte 32. A porous spinel layer 38 is provided thereon so as to cover the entire circumference or a part (in the illustrated example, a part) of the solid electrolyte 32. Furthermore, by using the same materials and processes as those in FIG. 2-element section 43
It is formed. The gas component detection element 41 in this fourth embodiment also has the same electric circuit configuration as shown in FIG. 8, so that the gas component detection element 41 as shown in FIG.
The relationship between the output and the amount of NOx is obtained, and the amount of NOx can be detected from the characteristics shown in FIG. (Embodiment 5) FIGS. 13 to 15 are diagrams showing a fifth embodiment of the gas component detection element according to the present invention. This gas component detection element 51 has a property that oxygen ion conductivity changes depending on the gas component in the atmosphere, and uses a solid electrolyte 53 having an air introduction hole 52 formed inside. A heater 55 covered with an insulating layer 54 is built inside, and two measurement electrodes 56 and 57 are provided on the outer peripheral surface of the solid electrolyte 53 to be exposed to the atmosphere to be measured. A reference electrode 58 in contact with the atmosphere is provided on the surface next to the introduction hole 52, and a porous spinel layer 59 is formed on the entire surface of the solid electrolyte 53 including the measurement electrodes 56 and 57. One electrode 56 of
On the surface of the spinel layer 59 in the portion where the measurement electrode is provided, a first element portion 62 is provided which is made of a porous catalyst layer containing a three-way catalyst component and has a reducing effect on NOx. On the surface of the spinel layer 59 in the part where the other electrode 57 is provided, a second element part 63 is provided, which is made of a porous catalyst layer containing an oxidation catalyst component and does not have a reducing effect on NOx. No.
Due to the difference in oxygen partial pressure between the re-measuring electrodes 56 and 57 caused by the difference in action between the two element parts 62 and 63 in the x atmosphere, the measuring electrodes 5 sandwiching the solid electrolyte 53
6 and the reference electrode 58, and the electromotive force output between the measurement electrode 57 and the reference electrode 58 which sandwich the solid electrolyte 53, this difference is measured. The structure is designed to detect NOx in the atmosphere. The procedure for manufacturing the gas component detection element 61 having such a structure will be further explained below. First, platinum cermet paste, which is a mixture of platinum and zirconia, is used on both sides of the zirconia green sheet.
A substrate material 53a formed with two measurement electrodes 56, 57 and a reference electrode 58 in contact with the atmosphere, a spacer material 53b formed with an air introduction hole 52 also using a zirconia green sheet, and covered with an insulating layer 54. A heater substrate 53c also made of a zirconia green sheet with a built-in heater 55 is heated and laminated to form a solid electrolyte 53, and then baked in the atmosphere at 1400° C. for 2 hours.
Next, spinel (M g O-A
A porous spinel layer 59 is formed by plasma spraying using a material such as Jl 20 s ) so as to cover all or a portion (in the illustrated example, all) of the solid electrolyte 53 . This spinel layer 59 may be omitted, but each measurement electrode 56,57
In order to increase the bonding strength between the element portion 62 and the catalyst layer 62 and 63, it is more preferable to have γ-A.
0.1 to 2 wt% of platinum (Pt) as a three-way catalyst component to n203, δ-An203, or a mixed powder thereof.
Alumina powder impregnated with 0.05 to 1 wt % of rhodium (Rh) is made into a slurry, and a first element portion 62 consisting of a three-way catalyst layer is formed by a spray method so as to cover one of the measurement electrodes 56 . Furthermore, γ'-A sentence 203
, δ-A 203 or a mixed powder of these is mixed with 0.1 to 2 wt% of platinum (Pt), or 0.1 to 2 wt% of platinum (Pt) and palladium (Pt) as an oxidation catalyst component.
Alumina powder impregnated with 0.05 to 1 wt % of d) is made into a slurry, and a second element portion 63 consisting of an oxidation catalyst layer is formed by spraying the slurry so as to cover the other measuring electrode 57. After forming the element portions 62 and 63 made of these catalyst layers, the gas component detection element 51 is obtained by firing in the atmosphere at 600'0 for 1 hour. Next, the operation of the gas component detection element 51 having the above configuration will be explained. First, by energizing the heater 55, the element temperature is raised to 6
The gas component detection element 51 was held at 00°C and exposed to exhaust gas from an internal combustion engine, and the air-fuel ratio dependence of the outputs of one measurement electrode 56 and the other measurement electrode 57 with respect to the reference electrode 5B in contact with the atmosphere was investigated. Ta. The results are shown in Figure 14. At this time, the NOx amount was kept constant at 1500 ppm, the engine operating conditions were 2000 rpm, and the torque 4.5 k.
g-m. As can be seen from FIG. 14, the measuring mold 1f is provided with a second element portion 63 made of a catalyst layer containing an oxidation catalyst.
The abrupt output change point of No. 157 shifts to the lean side compared to the stoichiometric air-fuel ratio due to the presence of NOx. On the other hand, the abrupt output change point of the measurement electrode 56 provided with the first element section 62 consisting of a catalyst layer containing a three-way catalyst component is
NO by producing and observing the reaction of NOx→N2+XO2
Since x is decomposed, the air-fuel ratio matches the stoichiometric air-fuel ratio regardless of the presence of NOx amount. Thus, for example, the reference electrode 5 in contact with the atmosphere
One measuring electrode 56 for 8 and also a reference electrode 58
By measuring the output difference between one measuring electrode 56 and the other measuring electrode 57, or the potential difference between one measuring electrode 56 and the other measuring electrode 57, output characteristics as shown in FIG. 15 can be obtained. Furthermore, as the amount of NOx decreases, the output of the other measuring electrode 57 relative to the reference electrode 58 approaches the stoichiometric air-fuel ratio, so the magnitude of the output depends on the amount of NOx, as shown in FIG. As it decreases, the output becomes smaller. Therefore, when the stoichiometric air-fuel ratio is controlled using the output of one measurement electrode 56 to the atmospheric reference electrode 58, the window of the three-way catalyst coincides with the sudden change point of the element output, so the purification efficiency of the catalyst is improved. , using the output characteristic of the 16th @, N
Since the amount of Ox can be detected, the amount of NOx can be reduced by controlling EGR or temporarily shifting the air-fuel ratio to the positive or positive side. Furthermore, since this gas component detection element 51 uses a material that is conventionally used in vehicles, it has durability such as heat resistance. Furthermore, a first layer consisting of a catalyst layer
03. to γ-8 so as to cover the element part 62 and the second element part 63. If the alumina layer is formed using δ-An203 or a mixture thereof, the durability is further improved. (Embodiment 6) FIG. 16 is a diagram showing a sixth embodiment of the gas component detection element according to the present invention. The gas component detection element 71 shown in the figure uses a hollow-tube solid electrolyte 53 having an air inlet hole 52 formed at one end, and the surface of the solid electrolyte 53 next to the air inlet hole 52 is filled with air A reference electrode 58 is provided in contact with the solid electrolyte 53, and two measurement electrodes 56 and 57 exposed to the atmosphere to be measured are provided on the outer peripheral surface of the solid electrolyte 53, including the re-measurement electrode 56 and 57 of the solid electrolyte 53. A porous spinel layer 59 is formed on the entire surface of the narrow diameter side, and a porous spinel layer 59 containing a three-way catalyst component is formed on the surface of the spinel layer 59 in the part where one of the measurement electrodes 56 is provided. A first element part 62 made of a porous catalyst layer is provided, and the surface of the spinel layer 59 in the part where the other electrode 57 of the measurement electrodes is provided is made of a porous catalyst layer containing an oxidation catalyst component. It has a structure in which a second element section 63 is provided. - Also in such a gas component detection element 71, there is an output difference between one measurement electrode 56 with respect to the reference electrode 58 in contact with the atmosphere and another measurement electrode 57 with respect to the reference electrode 58, or an output difference between one measurement electrode 56 and the other measurement electrode 56. By measuring the potential difference of the measurement electrode 57, output characteristics similar to those shown in FIG. 15 can be obtained. Also in this case, as the amount of NOx decreases, the output of the other measurement electrode 57 relative to the reference electrode 58 approaches the stoichiometric air-fuel ratio, so the output becomes smaller.

【Effect of the invention】

As described above, the gas component detection element according to the present invention includes a first NOx detection element section that includes a catalyst that has a reducing action on NOx, and a first element section that has a reducing action on NOx. The second NOx detection element section is equipped with a smaller amount of catalyst, and the NOx amount in the NOx atmosphere is detected based on the difference between the detection values of the two element sections in the NOx atmosphere. This provides an extremely excellent effect of being a gas component detection element suitable for detecting the amount of Nt)x in the combustion exhaust gas discharged from a commercial combustion engine.

[Brief explanation of the drawing]

FIG. 1 is an explanatory overall plan view of the gas component detection element according to the first embodiment of the present invention, and FIGS. 2(a) and 2(b) show the process of manufacturing the gas component detection element shown in FIG. Figure 2 (a)
is an explanatory plan view of one substrate material, FIG. 2(b) is an explanatory plan view of the other substrate material, FIG. 3 is an electrical equivalent circuit diagram of the gas component detection element shown in FIG. 1, and FIG. is a graph showing resistance value changes due to air-fuel ratio changes in the first and second element parts of the gas component detection element shown in FIG. 1, and FIG. 5 is a graph showing the air-fuel ratio of the gas component detection element shown in FIG. FIG. 6 is a graph showing the relationship between NOx amount and output of the gas component detection element shown in FIG. FIG. 8 is an explanatory diagram of a longitudinal section of a gas component detection element according to a third embodiment of the present invention, and FIG. 9 shows output changes due to air-fuel ratio changes of the gas component detection element shown in FIG. 8. Graph, FIG. 10 is a graph showing changes in partial pressure of ugly elements due to air-fuel ratio changes in the electrode portion of the gas component detection element shown in FIG. 8, and FIG. 11 is a graph showing NOx of the gas component detection element shown in FIG. 8.
FIG. 12 is a graph showing the relationship between quantity and output; FIG.
3 is a longitudinal cross-sectional explanatory diagram of a gas component detection element according to a fifth embodiment of the present invention, and FIG. FIG. 15 is a graph showing output changes due to changes in air-fuel ratio of the gas component detection element shown in FIG. It is a graph showing a change in resistance value due to a change in air-fuel ratio of a conventional gas component detection element. 1.21.31.41.51.71... Gas component detection element, 2.22, 42.62-... First element part (element part having a reducing effect on NOx), 3.23, 43.63...Second element 1 (element part that does not have a reducing effect on NOx). Patent applicant Daido Steel Co., Ltd. Representative Patent Attorney Yutaka Oshio N0x (ρpm) Partial pressure of several bundles (PO2)

Claims (1)

[Claims] (1) A first NOx detection element section equipped with a catalyst that has a reducing effect on NOx, and a second NOx detection element section equipped with a catalyst that has a smaller reducing effect on NOx than the first element section. 1. A gas component detection element, characterized in that the element is configured to detect the amount of NOx in the NOx atmosphere based on the difference in detected values in both the element parts in the NOx atmosphere.