JPH10252450A - Detector of combustible component in exhaust gas and catalyst activation capacity judging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge catalyst activation capacity for exhaust gas by providing a first temperature sensor which outputs a temperature signal which corresponds to a combustible component in exhaust gas and a second temperature sensor which detects a temperature of exhaust gas and calculating an amount of the combustible component in the exhaust gas based on a difference between temperature signals from both temperature sensors. SOLUTION: A sensor unit 100 provided with a first temperature sensor 1 which holds a catalyst on a surface thereof and a second ordinary temperature sensor 2 is attached by passing through a side wall of an exhaust pipe passage 4. An electrical signal which corresponds to a temperature of exhaust gas which flows in an exhaust pipe 4 and is generated by a thermo-couple is output from the first temperature sensor 1, and a temperature signal which corresponds to combustible components in the exhaust gas in which oxygen, hydrocarbon, carbon monoxide, etc., coexist is output. On the other hand, an electric signal which corresponds to a temperature of exhaust and is generated by a thermo-couple is output from the second temperature sensor 2. Output signals of each temperature sensor 1, 2 are input into a computing means 3 to calculate an amount of combustible components in the exhaust gas based on a difference between respective temperature signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the temperature of exhaust gas from an internal combustion engine by using a temperature sensor which outputs a temperature signal corresponding to a combustible component in exhaust gas in which combustible components such as oxygen, hydrocarbons and carbon monoxide coexist. The present invention relates to a device for detecting a combustible component in exhaust gas for detecting a combustible component contained therein, and a catalytic activity capability determination device for determining the catalytic activity capability of exhaust gas using the device.

[0002]

In an internal combustion engine such as the Related Art lean burn diesel engine or a gasoline lean-burn engines to perform, and that there is a large amount of oxygen in the exhaust, primarily fuel component Ya required in the NO _X purification in the catalytic device Hydrocarbons (HC) and carbon monoxide (CO),
Due to the shortage of unburned components such as hydrogen (H ₂ ), a method of improving the purification rate of nitrogen oxides (NO _x ) by supplying HC or the like as a reducing agent in exhaust gas has been proposed.

In such a method, for example, when HC is used as a reducing agent, a criterion for determining the amount of HC to be additionally supplied and a sensor for measuring the amount of HC and other combustible components are required. However, a practical device for detecting a combustible component in exhaust gas which can be easily installed in an exhaust pipe system of an engine, has good responsiveness, and can be used for controlling the supply amount of HC and other combustible components has not been developed.

Further, the catalyst system for the current of the NO _X purification,
The temperature range in which NO _X can be reduced is narrow (about 50K). In addition, when HC or the like is supplied to the exhaust gas as a reducing agent, if the amount is too large, fuel economy will be deteriorated. If the amount is too small, a sufficient NO _X reducing action cannot be obtained.

[0005] Thus, the catalytic converter installed in an exhaust conduit for of the NO _X reduction, in the system for supplying a reducing agent such as HC in the exhaust, as well as the temperature of the catalytic converter, the temperature of the exhaust and It is necessary to make a comprehensive judgment in consideration of the amount and composition of the reducing agent contained in the exhaust gas.

[0006] Conventionally, in an engine system using a catalyst to reduce the NO _X in the exhaust gas of lean burn, for example, the temperature of the exhaust and catalyst system was measured by the temperature sensor, detecting heat generated on the catalyst For example, a method of estimating a reaction state of a catalyst by using a method has been considered. However, since there is a temperature distribution in the catalyst device, there is a problem that the result differs depending on the place where the temperature is measured. In addition, since the heat capacity of the catalyst device is large, responsiveness when the temperature or composition of exhaust gas changes is poor, and it is difficult to respond satisfactorily to a transient operating state.

[0007]

[SUMMARY OF THE INVENTION] The above conventional method is to measure the temperature of the exhaust and the catalyst device by the temperature sensor, based on the detected temperature of the exhaust and catalyst system performs estimation calculation, NO _X purification However, as described above, it is impossible to accurately estimate the NO _X purification action with good responsiveness due to the temperature distribution in the catalyst device and the heat capacity of the catalyst device. In other words, even if it is detected that there is a temperature difference between the exhaust gas and the catalyst device, whether the temperature difference is due to the heat due to the reaction in the catalyst device or the temperature difference is temporarily detected due to the heat capacity of the catalyst device. It is not possible to judge whether the temperature difference disappears after a while or whether the local temperature at which the temperature becomes the highest in the catalyst device is detected. In order to solve the above problems, it is necessary to measure the amount of the NO _X reducing agent in the exhaust gas (i.e. combustible components). This is because, in order to operate effectively a catalyst for of the NO _X reduction, because the catalyst is required to supply the necessary amount of a reducing agent in the exhaust temperature NO _X suitable for performing the NO _X reduction by is there.

The inventors of the present invention have premised on the fact that the combustible gas mixture reacts on the surface of the catalyst to generate heat, and the exhaust gas containing oxygen and combustible components such as hydrocarbons and carbon monoxide coexists. The combustible component in the exhaust gas is determined based on the difference between the temperature signal from the first temperature sensor that outputs a temperature signal corresponding to the combustible component in the second temperature sensor and the second temperature sensor that detects the exhaust temperature and outputs the temperature signal. Focusing on the first technical idea of the present invention of detecting, a combustible component in the exhaust gas and exhaust gas detected based on a difference between temperature signals from the first temperature sensor and the second temperature sensor. The result of further research and development focusing on the second technical idea of the present invention of determining the catalytic activity of exhaust gas by comparing the purification characteristics of the exhaust gas purifying catalyst device provided in the pipe Within A sensor that can be easily installed in an exhaust pipe of an engine and that can detect the amount of HC and CO and other combustible components in exhaust gas containing oxygen is realized. The present invention has been achieved which achieves the purpose of determining whether the temperature and composition are suitable for the device and enabling the determination of the catalytic activity of the exhaust gas.

[0009]

According to a first aspect of the present invention, there is provided a device for detecting a combustible component in exhaust gas, comprising an exhaust gas in which oxygen and combustible components such as hydrocarbons and carbon monoxide coexist. A first temperature sensor that outputs a temperature signal corresponding to a combustible component therein, a second temperature sensor that detects an exhaust gas temperature and outputs a temperature signal, the first temperature sensor and the second temperature Calculating means for calculating the amount of combustible components in the exhaust gas based on the difference between the temperature signals from the sensors.

The present invention (second invention described in claim 2)
A first temperature sensor that outputs a temperature signal corresponding to a combustible component in exhaust gas in which combustible components such as oxygen and hydrocarbons or carbon monoxide coexist, and detects an exhaust gas temperature. A second temperature sensor for outputting a temperature signal by
Calculating means for calculating the amount of the combustible component in the exhaust gas detected based on the difference between the temperature signals from the first temperature sensor and the second temperature sensor; and the calculated combustible component in the exhaust gas And a determination means for determining the catalytic activity of the exhaust by comparing the purification characteristics of the exhaust purification catalyst device disposed in the exhaust pipe.

The device for detecting a combustible component in exhaust gas according to the present invention (third invention) includes an absolute temperature detected by a device having a catalyst carried on the surface of a temperature sensor, an absolute temperature detected by another temperature sensor, or an absolute temperature detected by another temperature sensor. The amount of combustible components in the exhaust gas in which oxygen and combustible components (mainly hydrocarbons and CO) coexist is detected from the temperature difference.

For example, a temperature sensor carrying a catalyst on the surface of a thermocouple is installed in an exhaust pipe so as to be exposed to exhaust gas.
Since the temperature sensor is affected by the heat generated when flammable components such as HC in the exhaust gas are oxidized on the catalyst, a temperature higher than the temperature of the exhaust gas when oxygen and the combustible components coexist in the exhaust gas. Is shown. Therefore, the temperature detected by the device,
The amount of the combustible component in the exhaust gas can be detected by comparing the temperature of the exhaust gas or the measured temperature of another temperature sensor of the same type having different temperature characteristics.

[0013] The catalyst activity determining apparatus of the present invention (fourth invention) is characterized in that an absolute temperature or a temperature difference obtained from the combustible component detecting apparatus of the third invention and an exhaust purification catalyst device provided in an exhaust pipe. By comparing the purification characteristics, the catalytic activity of the exhaust gas is determined.

That is, using the principle of the combustible component detecting device according to the third aspect of the present invention, the absolute temperature measured by the device and the measured value of another temperature sensor are converted into the exhaust gas purifying catalyst device installed in the exhaust pipe. It is possible to determine whether the exhaust gas temperature and composition are suitable for the exhaust gas purifying catalyst device by comparing with the purifying characteristics (particularly, the relation between the purifying ability and the temperature).

[0015]

According to the first aspect of the present invention, there is provided a device for detecting a combustible component in exhaust gas according to the first invention, wherein the arithmetic means includes a combustible component in the exhaust gas in which combustible components such as oxygen and hydrocarbons or carbon monoxide coexist. Outputting the first temperature signal corresponding to the component;
The amount of combustible components in the exhaust gas is calculated based on the difference between the temperature signals from the temperature sensor and the second temperature sensor that detects the exhaust gas temperature and outputs a temperature signal. Of the present invention, it is possible to accurately detect the amounts of HC and CO and other combustible components in the exhaust gas in which oxygen is present.

According to a second aspect of the present invention, there is provided a catalyst activity determining apparatus according to a second aspect of the present invention, wherein the arithmetic means includes a temperature signal corresponding to a combustible component in the exhaust gas in which a combustible component such as oxygen and a hydrocarbon or carbon monoxide coexists. Calculating the amount of combustible components in the exhaust gas based on the difference between the temperature signals from the first temperature sensor that outputs the first temperature sensor and the second temperature sensor that detects the exhaust temperature and outputs a temperature signal; The determining means determines the catalytic activity of the exhaust gas by comparing the calculated combustible component in the exhaust gas with the purifying characteristics of the exhaust gas purifying catalyst device provided in the exhaust pipe. It is possible to determine whether the temperature and the composition are suitable for the purifying catalyst device and to determine the catalytic activity of the exhaust gas.

According to a third aspect of the present invention, there is provided a device for detecting a combustible component in exhaust gas, comprising: an absolute temperature detected by the temperature sensor carrying a catalyst on a surface installed in an exhaust pipe so as to be exposed to the exhaust gas; Since the amount of combustible components in the exhaust gas in which oxygen and combustible components (mainly hydrocarbons and CO) coexist is detected from the absolute temperature detected by another temperature sensor or the temperature difference therebetween, the oxygen and the combustible components are detected. From the measured temperature corresponding to the possible component, the measured temperature of another temperature sensor, and the difference between them, it is possible to accurately determine the amount of the combustible component in the exhaust gas containing oxygen.

The catalyst activity determining apparatus according to the fourth aspect of the present invention comprises an absolute temperature or a temperature difference obtained from the combustible component detecting apparatus according to the third aspect of the present invention and an exhaust purification catalyst apparatus provided in an exhaust pipe. Since the catalytic activity of the exhaust gas is determined by comparing the purifying characteristics, the exhaust purifying catalyst device installed in the exhaust pipe using the principle and the detection of the amount of the combustible component in the third invention described above. In order to compare the purification characteristics (particularly the relationship between the purification performance and the temperature) of the exhaust gas, it is possible to determine whether the temperature and the composition of the exhaust gas are suitable for the exhaust purification catalyst device.

Here, the amount of combustible components in the exhaust refers to the amount of each combustible component or the total amount of combustible components.

[0020]

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

(First Embodiment) In the device for detecting a combustible component in exhaust gas according to the first embodiment, as shown in FIGS. 1 to 4, oxygen and combustible components such as hydrocarbons and carbon monoxide coexist. A first temperature sensor 1 for outputting a temperature signal corresponding to a combustible component in the exhaust gas, a second temperature sensor 2 for detecting an exhaust gas temperature and outputting a temperature signal, the first temperature sensor 1 and the Calculation means 3 for calculating the amount of combustible components in the exhaust gas based on the difference between the temperature signals from the second temperature sensor 2
It consists of:

As shown in FIG. 1, the apparatus for detecting a combustible component in exhaust gas of the first embodiment penetrates the side wall of the exhaust pipe 4 and connects the first and second temperature sensors 1 and 2 to each other. The sensor unit 100 provided is mounted, and the temperature measurement unit at the tip is installed so as to be exposed to the exhaust gas flowing in the exhaust pipe.

As shown in FIG. 2, the sensor unit 100 has, as an example, the first temperature having a catalyst supported on the surface thereof so as to make the temperature conditions of the first and second temperature sensors 1 and 2 the same. Two sensors 1 and a normal temperature sensor 2 are arranged on the upper surface of the mounting screw 101.

The first temperature sensor 1 carrying a catalyst on its surface has a temperature measuring portion at the protruding tip of a protective tube 10 having a lower portion fixed to a mounting screw 101 as shown in FIG. Constitute the sensor section.

The upper portion of the protective tube 10 is covered with a carrier 12, and a catalyst 13 is carried on the surface. In order to reduce heat transfer to the sensor unit side, the upper half of the protective tube 10 is covered with the catalyst 13 and is attached to the sensor unit 100 via a ceramics tube 14 of an annular member. It is attached by a metal supporting part such as a screw 101.

The structure of the tip of the first temperature sensor carrying the catalyst 13 is shown in detail in FIG. In FIG. 4, a thermocouple 11 is used as a temperature sensor.
The thermocouple 11 is insulated and supported by a solid cylindrical insulator 15 in the protection tube 10, and only the temperature measuring contact portion is exposed before the protection tube. These are all covered with the carrier 12,
The catalyst 13 is carried on the surface.

That is, the first temperature sensor 1 outputs an electric signal (indicated by a broken line in FIG. 5) from the thermocouple 11 according to the temperature of the exhaust gas flowing through the exhaust pipe 4 as shown in FIG. Outputs a temperature signal according to the combustible components in the exhaust gas, in which combustible components such as oxygen and hydrocarbons and carbon monoxide coexist. It is configured to output a signal (indicated by a solid line in FIG. 5) on which an electric signal corresponding to the amount of the component is superimposed.

The second temperature sensor 2 is different from the first temperature sensor only in that the protection tube is longer and the catalyst is not supported. The second temperature sensor 2 has a similar configuration using a thermocouple 11 as a temperature sensor. As shown by a broken line in FIG. 5, the electric signal is output by the thermocouple 11 according to the temperature of the exhaust gas, and the description is omitted.

The calculating means 3 is provided with the sensor unit 1
The first temperature sensor 1 is connected to the first and second temperature sensors 1 and 2 of FIG.
And the difference (shown by hatching in FIG. 5) between the respective temperature signals indicated by solid lines and broken lines in FIG. 5 detected and output by the second temperature sensor 2 is determined by an experiment and stored in a memory. The amount of the combustible component in the exhaust gas is calculated according to the difference between the obtained temperature signals.

In the device for detecting combustible components in exhaust gas according to the first embodiment having the above-mentioned configuration, the calculating means 3 determines the combustible components in the exhaust gas in which oxygen and combustible components such as hydrocarbons and carbon monoxide coexist. The first temperature sensor 1 that outputs a corresponding temperature signal (shown by a solid line in FIG. 5) and the second temperature sensor 2 that detects the exhaust gas temperature and outputs a temperature signal (shown by a broken line in FIG. 5) The amount of the combustible component in the exhaust gas is calculated based on the difference between the temperature signals (indicated by hatching in FIG. 5).

That is, a signal corresponding to a combustible component in exhaust gas detected by the first temperature sensor 1 carrying a catalyst on a surface provided in the exhaust pipe 4 so as to be exposed to the exhaust gas is superimposed. From the temperature difference between the first absolute temperature and the absolute temperature corresponding only to the exhaust gas temperature detected by the second temperature sensor, oxygen and combustible components (mainly hydrocarbons and CO ) Is calculated for the amount of combustible components in the exhaust that coexist.

The device for detecting a combustible component in exhaust gas according to the first embodiment, which has the above-described operation, is capable of performing combustion in exhaust gas based on a difference between temperature signals from the first temperature sensor 1 and the second temperature sensor 2. Since the amounts of the components are calculated, it is possible to easily install the internal combustion engine in the exhaust pipe 4 and accurately detect the amounts of HC, CO, and other combustible components in the exhaust gas containing oxygen. And the response in detection is enhanced.

(Second Embodiment) As shown in FIGS. 6 to 9, a device for detecting combustible components in exhaust gas according to the second embodiment is different from the first embodiment. This is mainly for considering the durability at a relatively high temperature, and the response is slightly inferior to that of the first embodiment. Hereinafter, the difference will be mainly described.

As is apparent from FIG. 6, the sensor unit of the combustible component detecting device according to the second embodiment is attached to the exhaust pipe 4, and the first temperature sensor 1 carrying the catalyst 13 is an exhaust gas. It is installed so as to oppose the flow.

The first temperature sensor carrying a catalyst comprises:
As shown in FIG. 9, the tip of the sensor is formed in a hemispherical shape, and the catalyst 13 is carried on the entire hemispherical surface. The catalyst 1
The inside of 3 is composed of a carrier 12 and a ceramics cover 14, and a thermocouple 11 at the tip of a temperature measuring unit constituting a temperature sensor.
Is in direct contact with the carrier 12.

When the amount of HC (hydrocarbon) in high-temperature air is changed using the apparatus for detecting combustible components in exhaust gas according to the second embodiment, the results shown in FIG. 5 are obtained. The output of the normal temperature sensor (second temperature sensor) indicated by the broken line is substantially constant regardless of the amount of HC unless the temperature changes. On the other hand, the temperature measured by the temperature sensor (first temperature sensor) supporting the catalyst increases as the amount of HC increases. This seems to indicate that heat is generated by the oxidation reaction on the catalyst.

FIG. 5 shows the characteristics of the catalyst, the temperature of the exhaust gas,
It is determined by the composition of the combustible components in the exhaust gas. Therefore,
If these characteristics are mapped in advance, it becomes possible to estimate the amount of combustible components in the exhaust from the outputs of the two temperature sensors as shown in FIG.

The device for detecting a combustible component in exhaust gas according to the second embodiment, which has the above-described operation, is capable of performing combustion in exhaust gas based on a difference between temperature signals from the first temperature sensor 1 and the second temperature sensor 2. Since the amounts of the components are calculated, it is possible to accurately detect the amounts of HC, CO, and other combustible components in the exhaust gas in which oxygen is present, and to improve the durability at high temperatures.

(Third Embodiment) The device for detecting combustible components in exhaust gas of the third embodiment uses two temperature sensors carrying a catalyst as shown in FIGS. The following is a description mainly of the differences.

First and second temperature sensors 1 and 2
Is a temperature sensor in which a catalyst 13 is carried on the surface of each sensor in the same manner as the first temperature sensor of the first embodiment. However, the carried catalyst substance is different, so that an exothermic reaction occurring on the catalyst is generated. The activation temperature conditions are set differently.

In the third embodiment, as shown in FIG. 10, the catalyst carried by the second temperature sensor 2 is:
The reaction is promoted at a higher temperature than the first temperature sensor 1. Therefore, even when the first temperature sensor 1 is strongly affected by the exothermic reaction, the second temperature sensor 2 hardly detects the heat generated by the reaction at a relatively low temperature.

With the output of the first temperature sensor 1 alone,
As a matter of course, the amount of HC in the exhaust gas cannot be uniquely known. For example, as shown in FIG. 11, when the first output value of the temperature sensor 1 of is a _1, unless it is not possible to know the amount of HC know the temperature of the exhaust gas.

Therefore, if a second temperature sensor 2 having different activation characteristics is provided instead of a normal temperature sensor for measuring the temperature of exhaust gas, the amount of HC can be determined from the output values of the first and second temperature sensors. Can be. For example, when the first output of the temperature sensor 1 of is a _1, the first temperature sensor 2
Weight HC if the output of b ₁ is M _1, the second output of the temperature sensor 2 of HC amount if b ₂ becomes M _2.

The device for detecting a combustible component in exhaust gas of the third embodiment having the above-described operation is based on a difference in temperature signal between the first temperature sensor 1 and the second temperature sensor 2 due to a difference between the two characteristics. Since the amount of the combustible component in the exhaust gas is calculated, an effect of enabling accurate detection of the amounts of HC, CO, and other combustible components in the exhaust gas in which oxygen exists is achieved.

(Fourth Embodiment) As shown in FIG. 12 and FIG. 13, the catalytic activity ability judgment apparatus of the fourth embodiment uses the exhaust gas in which oxygen and combustible components such as hydrocarbons and carbon monoxide coexist. A first temperature sensor 1 for outputting a temperature signal corresponding to a combustible component of the first temperature sensor, a second temperature sensor 2 for detecting an exhaust gas temperature and outputting a temperature signal, the first temperature sensor 1 and the second temperature sensor Calculating means 3 for calculating a combustible component in the exhaust gas in which a combustible component in the exhaust gas is detected based on a difference between the temperature signals from the temperature sensor 2 of the above; and the calculated combustible component in the exhaust gas and the exhaust pipe The determination means 5 determines the catalytic activity of the exhaust gas by comparing the purification characteristics of the exhaust gas purifying catalyst device 6 disposed in the exhaust gas purifying catalyst device 4.

From the temperature difference between the absolute temperature detected by the first temperature sensor 1 carrying the catalyst 13 on the surface and the absolute temperature detected by the second temperature sensor 2, oxygen and combustible components (mainly It detects a combustible component in exhaust gas in which hydrocarbons and CO) coexist.

That is, the first temperature sensor 1, which is installed in the exhaust pipe 4 so as to be exposed to the exhaust gas and carries the catalyst 13 on the surface of the thermocouple 11, emits combustible components such as HC in the exhaust gas. The temperature is higher than the temperature of the exhaust gas when oxygen and combustible components coexist in the exhaust gas because it is affected by the heat generated when being oxidized on the catalyst. Therefore, the combustible component in the exhaust gas is calculated by comparing the detected temperature with the temperature of the exhaust gas or the measured temperature of the second temperature sensor 2 of the same type having different temperature characteristics.

The amount of the combustible component in the exhaust gas obtained from the absolute temperature corresponding to the amount of the combustible component calculated by the calculating means 3 and the absolute temperature corresponding to the temperature of the exhaust gas, By comparing the purification characteristics (particularly, the relationship between purification ability and temperature) of the exhaust purification catalyst device 6 installed in the exhaust gas by the determination means 5, the exhaust gas temperature and composition are suitable for the exhaust purification catalyst device. Is determined.

That is, since not only NO _x but also a large amount of oxygen remains in the exhaust gas flowing through the exhaust pipe 4 due to the lean combustion, the N
O _X, CO, hardly effective catalysis, as seen in three-way catalyst for purifying HC is obtained.

The catalyst has a limited temperature range which act effectively, in order to purify NO _X in the exhaust gas of the lean burn in order that the catalyst of the exhaust purifying catalyst device 6, the exhaust gas temperature suitable for catalyst it is necessary to supply a reducing agent for reducing NO _X in.

The NO _X reduction rate of the NO _X reduction catalyst as shown in FIG. 14 is effective only in a range of exhaust temperatures. NO below or above the temperature range
_X reduction effect decreases. Therefore, the amount of NO _X to be reduced and the amount of NO _X discharged from the engine, necessarily NO _X
The temperature range in which the reduction is effectively performed is determined. Within this temperature range, NO _X can be reduced by supplying a reducing agent necessary for NO _X reduction.

By using the absolute temperature detected by the first to third embodiments and the calculated combustible components, it is possible to detect the temperature of the exhaust gas and the amount of the combustible components simultaneously. Under conditions where the temperature measured by the first temperature sensor carrying the catalyst is higher than the temperature measured by the normal second temperature sensor (the lower right part of the 45 ° slope line in FIG. 14B), the combustible components are Indicates that it is contained in the exhaust. Further, as shown in FIG. 5, the amount of the combustible component in the exhaust gas can be estimated from the output of the device for detecting the combustible component.

[0053] Therefore, as shown in FIG. 14 (B), located in the effective range to the NO _X reduction of the temperature of the exhaust catalyst still and, temperature measured by the temperature sensor 1 of the first carrying a catalyst higher conditions than the normal second temperature measured by the temperature sensor 2, that is, if the conditions of the cross-hatching in FIG 14 (B), the catalytic converter for the reduction of the NO _X is in the effective exhaust temperature and thus it contains combustible components necessary to the NO _X reduction.

Further, the principle described above and FIG.
By using both the method of detecting combustible component amount described using, is to comprehensively determine exhaust is suitable taken to the catalytic converter 6 for of the NO _X reduction.

The apparatus for determining the catalytic activity ability of the fourth embodiment is characterized in that the temperature difference between the temperature signal corresponding to the combustible component in the exhaust gas and the absolute temperature obtained from the exhaust gas temperature signal, Since the catalytic activity of the exhaust gas is determined by comparing the purification characteristics based on the relationship between the purification performance and the temperature of the exhaust gas purifying catalyst device 6, the temperature and composition of the exhaust gas are suitable for the exhaust gas purifying catalytic device 6. This is advantageous in that it is possible to determine whether or not

The above-described embodiments are exemplarily described for explanation, and the present invention is not limited to these embodiments. Those skilled in the art will recognize from the claims, the detailed description of the invention, and the drawings. Modifications and additions are possible without departing from the technical idea of the present invention.

That is, the present invention detects the combustible components in the exhaust gas by utilizing the exothermic effect of the reaction of the combustible gas-fuel mixture on the catalyst surface, and also uses this principle to determine the composition and temperature of the exhaust gas. The present invention proposes an apparatus for determining whether or not is suitable for an exhaust gas purifying catalyst, and is not limited to the above embodiment unless the basic idea of the present invention is violated.

In the first embodiment, an example in which the first and second temperature sensors 1 and 2 are integrated as one unit has been described from the above viewpoint as an example. However, the present invention is not limited thereto. Not something
It is possible to adopt a mode in which the first temperature sensor 1 carrying the catalyst and the normal second temperature sensor 2 are formed as separate units, and are installed in respective mounting holes at different positions on the side wall of the exhaust pipe 4.

In the present invention, the catalyst substance carried on the temperature sensor does not necessarily need to be the same as the substance used in the catalyst device for purifying exhaust gas. Further, two or more sensors carrying a catalyst may be used.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an arrangement of an apparatus for detecting a combustible component in exhaust gas in an exhaust pipe according to a first embodiment of the present invention.

FIG. 2 is a front view showing a sensor unit of the device for detecting a combustible component in exhaust gas according to the first embodiment.

FIG. 3 is a cross-sectional view illustrating a first temperature sensor according to the first embodiment.

FIG. 4 is an enlarged sectional view showing a main part of the first temperature sensor of the first embodiment.

FIG. 5 is a diagram showing the relationship between the amount of combustible components in exhaust gas and the output in the first and second temperature sensors of the first embodiment.

FIG. 6 is a cross-sectional view showing an arrangement of an apparatus for detecting a combustible component in exhaust gas in an exhaust pipe according to a second embodiment of the present invention.

FIG. 7 is a side view showing a sensor unit of the device for detecting a combustible component in exhaust gas according to the second embodiment.

FIG. 8 is a rear view showing a sensor unit of the device for detecting a combustible component in exhaust gas according to the second embodiment.

FIG. 9 is an enlarged sectional view showing a main part of a first temperature sensor of the second embodiment.

FIG. 10 is a front view showing a sensor unit of a device for detecting a combustible component in exhaust gas according to a third embodiment of the present invention.

FIG. 11 is a graph showing the relationship between the amount of combustible components in exhaust gas and the output in the first and second temperature sensors of the third embodiment.

FIG. 12 is a block diagram illustrating a catalyst activity ability determination device according to a fourth embodiment of the present invention.

FIG. 13 is a chart showing a detection procedure according to the fourth embodiment.

FIG. 14 is a diagram showing a relationship between a NOx reduction rate and an exhaust gas temperature in the fourth embodiment, and a diagram showing a relationship between a temperature output of a temperature sensor carrying a catalyst and an exhaust gas temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st temperature sensor 2 2nd temperature sensor 3 Computing means 4 Exhaust pipe line 5 Judgment means 6 Exhaust purification catalyst device 100 Sensor unit 101 Mounting screw 10 Protective tube 11 Thermocouple 12 Carrier 13 Catalyst 14 Ceramic tube 15 Insulator

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI F01N 7/00 ZAB F02D 45/00 360C F02D 45/00 ZAB G01M 15/00 ZABZ 360 B01D 53/36 ZAB G01M 15/00 ZAB 101B 103B

Claims (2)

[Claims] 1. A first temperature sensor for outputting a temperature signal corresponding to a combustible component in exhaust gas in which combustible components such as oxygen and hydrocarbons and carbon monoxide coexist, and a temperature signal for detecting exhaust gas temperature. And a calculating means for calculating the amount of combustible components in the exhaust gas based on the difference between the temperature signals from the first temperature sensor and the second temperature sensor. A device for detecting combustible components in exhaust gas. 2. A first temperature sensor for outputting a temperature signal according to a combustible component in exhaust gas in which combustible components such as oxygen and hydrocarbons and carbon monoxide coexist, and a temperature signal which detects exhaust gas temperature. A second temperature sensor that outputs the following: a calculation unit that calculates an amount of a combustible component in the exhaust gas detected based on a difference between temperature signals from the first temperature sensor and the second temperature sensor; Determining means for determining the catalytic activity of the exhaust gas by comparing the calculated amount of the combustible component in the exhaust gas with the purification characteristics of the exhaust gas purifying catalyst device provided in the exhaust pipe. Characteristic catalyst activity determination device.