JP2000291423A - Catalyst deterioration determining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and precisely determine a catalyst deterioration device for determining the deterioration of a catalyst. SOLUTION: This catalyst deterioration determining device 1 determines deterioration of a catalytic converter 2 provided on an exhaust system of an internal combustion engine. The catalyst deterioration determining device 1 has an outlet gas temperature detection means 11 for detecting outlet gas temperature of the catalytic converter 2, a dummy catalyst exhaust gas temperature estimating means 12 for estimating dummy catalyst exhaust gas temperature, and a deterioration determining mean 13 for determining the deterioration of the catalyst based on the outlet gas temperature detected by the outlet gas temperature detection means and the dummy catalyst exhaust gas temperature estimated by the dummy catalyst exhaust gas temperature estimating means. The dummy catalyst exhaust gas temperature is the outlet gas temperature, when the catalytic converter 2 is assumed to be a dummy catalyst which does not actually carry catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst deterioration judging device for judging deterioration of a catalyst of a catalytic converter provided in an exhaust system of an internal combustion engine with high accuracy.

[0002]

2. Description of the Related Art An exhaust system of an internal combustion engine used in an automobile is generally provided with a catalytic converter for purifying harmful components in exhaust gas. In general, the catalyst carried by the above-mentioned catalytic converter deteriorates with a long use, and the ability to purify harmful components is attenuated. Under normal operating conditions, it is guaranteed that the performance of the catalytic converter will surpass a certain level during the warranty period of the internal combustion engine. However, abnormalities in the internal combustion engine, auxiliary equipment, fuel, etc. may cause abnormal deterioration of the catalyst. Is also assumed. For this reason, it is necessary to judge the deterioration state of the catalyst and notify the driver of the deterioration to urge the replacement of the catalytic converter.

[0003] Replacement of the above-mentioned catalytic converter requires considerable cost and time, so that it must be minimized. Therefore, it is necessary to accurately judge the deterioration of the catalyst. JP-A-8-270438 describes a means for estimating a catalyst temperature in a catalytic converter and a device for judging catalyst deterioration from a comparison of measured catalyst temperatures.

[0004]

However, in the conventional method described above, the degree of deterioration is grasped by estimating the catalyst outlet temperature of the catalyst when the deterioration has advanced and exceeding the service limit, and comparing the estimated catalyst outlet temperature with the measured catalyst outlet temperature. In addition, the timing of catalyst replacement is determined. In addition, this estimation deals with the exothermic reaction accompanying the combustion of hydrocarbons in the catalyst carrier carrying the catalyst.

[0005] However, the estimation of the catalyst temperature during the exothermic reaction by hydrocarbons is very complicated and cannot be predicted by a linear equation as described in JP-A-8-270438. For example, it varies greatly depending on the type and amount of hydrocarbon and the concentration of oxygen. Further, the temperature of the catalyst during the reaction varies depending on its position, and the accuracy is deteriorated in the deterioration judgment using one point temperature measurement as described in JP-A-8-270438. Therefore, the catalyst deterioration determination method described cannot provide a sufficiently accurate catalyst deterioration determination.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a catalyst deterioration determining device capable of easily and accurately determining catalyst deterioration.

[0007]

According to a first aspect of the present invention, there is provided a catalyst deterioration judging device for judging deterioration of a catalyst of a catalytic converter provided in an exhaust system of an internal combustion engine. Outlet gas temperature detecting means for detecting the outlet gas temperature of the converter, dummy catalyst exhaust gas temperature estimating means for estimating the dummy catalyst exhaust gas temperature shown below, and the outlet gas temperature detected by the outlet gas temperature detecting means and the dummy gas temperature And a deterioration judging means for judging the deterioration of the catalyst based on the dummy catalyst exhaust gas temperature estimated by the catalyst exhaust gas temperature estimating means. The catalyst deterioration determination device is characterized in that the temperature is the outlet gas temperature when the dummy catalyst is not performed.

[0008] Most notably, in the present invention, the catalyst deterioration judging device estimates a dummy catalyst exhaust gas temperature which is an outlet gas temperature when the catalytic converter does not carry a catalyst. That is, it has a temperature estimating means.

The deterioration determining means determines, for example, the presence or absence of catalyst deterioration as described below. That is, when there is almost no difference between the outlet gas temperature detected by the outlet gas temperature detecting means and the dummy catalyst exhaust gas temperature estimated by the dummy catalyst exhaust gas temperature estimating means, it is determined that the catalyst is in a deteriorated state. . On the other hand, if there is a sufficient difference between the outlet gas temperature and the dummy catalyst exhaust gas temperature, it is determined that the catalyst has not deteriorated.

[0010] The dummy catalyst exhaust gas temperature estimating means includes:
This is a means for estimating the outlet gas temperature when it is assumed that the catalytic converter does not carry a catalyst, based on the engine operation information of the internal combustion engine. The above-mentioned engine operation information is, for example,
It refers to the engine speed, torque, intake air amount, exhaust gas flow rate, inlet gas temperature of the catalytic converter, the amount of hydrocarbons contained in the exhaust gas, and the like.

The outlet gas temperature refers to the temperature of the exhaust gas at the outlet of the catalytic converter, and the inlet gas temperature refers to the temperature of the exhaust gas at the inlet of the catalytic converter. In addition, "the catalytic converter does not substantially support the catalyst" means that the catalyst does not actually support the catalyst, and the catalyst does not substantially support the catalyst even if the catalyst converter supports the catalyst. This includes cases in which activity has been lost.

Next, the operation of the present invention will be described. The catalyst deterioration determination device estimates a dummy catalyst exhaust gas temperature based on engine operation information and the like. Further, the outlet gas temperature of the catalytic converter is detected by an outlet gas temperature detecting means. Then, catalyst deterioration is determined by comparing the estimated dummy catalyst exhaust gas temperature with the detected outlet gas temperature.

That is, when the active state of the catalyst is sufficient, the temperature of the exhaust gas rises due to the combustion of the hydrocarbons entering the catalyst. However, as the catalyst deteriorates, hydrocarbons do not burn,
The exhaust gas temperature also does not rise. Therefore, when the activity of the catalyst is sufficient, there is a difference between the outlet gas temperature and the temperature of the exhaust gas of the dummy catalyst. It is about the same as the catalyst exhaust gas temperature. Therefore, the deterioration of the catalyst is determined based on the temperature difference.

Next, the effects of the present invention will be described. The catalyst deterioration determination device has a dummy catalyst exhaust gas temperature estimating means for estimating a dummy catalyst exhaust gas temperature which is an outlet gas temperature when the catalyst converter does not substantially support a catalyst. Since the dummy catalyst does not carry a catalyst, it is not necessary to consider the reaction heat due to the catalytic reaction, which is difficult to estimate accurately, in estimating the catalyst exhaust gas temperature. Therefore, the temperature of the dummy catalyst exhaust gas can be accurately and easily estimated. Therefore, it is possible to easily and accurately determine the catalyst deterioration based on the difference between the catalyst outlet gas temperature and the dummy catalyst exhaust gas temperature.

Further, since the temperature of the dummy catalyst exhaust gas is estimated from the temperature of the gas discharged from the catalytic converter, it is not necessary to consider the temperature in the catalytic converter and the gas temperature distribution in the catalytic converter. Similarly, the outlet gas temperature detecting means detects the gas temperature of the portion where the gas discharged from the catalytic converter is uniformly mixed, and is not affected by the gas temperature distribution in the catalytic converter. Therefore, the outlet gas temperature detecting means can obtain an accurate measured value. Therefore, the catalyst deterioration can be easily and accurately determined.

As described above, according to the present invention, it is possible to provide a catalyst deterioration determining apparatus capable of easily and accurately determining catalyst deterioration.

Next, it is preferable that the dummy catalyst exhaust gas temperature estimating means is constituted by a neural network having a nonlinear conversion function and a learning function. That is, a neural network is used as a model of the dummy catalyst. Then, the relationship between the operation information of the engine and the gas temperature at the outlet of the dummy catalyst is determined by an experiment using the dummy catalyst, and the neural network is learned. The above-mentioned non-linear conversion function is an operation function of a general neural network operation element, for example, “Rumelhart, DH, e
t al., Learning Representation by Back-propagation
Errors, Nature, Vol. 322 (1986), p. 533 ".

The temperature of the exhaust gas of the dummy catalyst changes transiently with a change in the operating state of the engine. Since the above-mentioned neural network has the above-mentioned nonlinear conversion function, it can cope with such a transient change of the dummy catalyst exhaust gas temperature,
A more accurate estimation can be made. Further, since the neural network has a learning function, it is possible to easily imitate the complicated thermal properties of a catalytic converter that does not carry a catalyst. This makes it possible to more easily and accurately determine catalyst deterioration.

Next, according to a third aspect of the present invention, the catalyst deterioration judging device has an inlet gas temperature detecting means for detecting an inlet gas temperature entering the catalytic converter, and the dummy catalyst discharging means. Preferably, the gas temperature estimating means estimates the dummy catalyst exhaust gas temperature using the inlet gas temperature detected by the inlet gas temperature detecting means.

For example, a thermometer is installed at the inlet pipe of the catalytic converter to directly measure the inlet gas temperature. As a result, the temperature of the exhaust gas that has entered the catalytic converter can be ascertained, and by using this to estimate the outlet gas temperature, the accuracy of the outlet gas temperature estimation can be improved.
Therefore, it is possible to more accurately determine the deterioration of the catalyst.

Next, according to a fourth aspect of the present invention, the catalyst deterioration judging device has an inlet gas temperature estimating means for estimating an inlet gas temperature entering the catalytic converter, and the dummy catalyst discharging means. The gas temperature estimating means can also estimate the dummy catalyst exhaust gas temperature using the inlet gas temperature estimated by the inlet gas temperature estimating means. That is, the temperature of the exhaust gas entering the catalyst is estimated from the engine operation information and the like. Also in this case, the accuracy of estimating the outlet gas temperature can be improved, as in the invention described in claim 3.
The catalyst deterioration can be more accurately determined.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A catalyst deterioration judging device according to an embodiment of the present invention will be described.
This will be described with reference to FIGS. The catalyst deterioration determination device 1 of the present embodiment includes a catalytic converter 2 provided in an exhaust system of an internal combustion engine.
This is a device for determining the deterioration of the catalyst. As shown in FIG. 1, the catalyst deterioration determination device 1 includes the following outlet gas temperature detection means 11 and dummy catalyst exhaust gas temperature estimation means 1
2 and deterioration determination means 13.

The outlet gas temperature detecting means 11 is a means for detecting the outlet gas temperature of the catalytic converter 2.
The dummy catalyst exhaust gas temperature estimating means 12 is means for estimating the dummy catalyst exhaust gas temperature. The dummy catalyst exhaust gas temperature is the outlet gas temperature when the catalytic converter 2 is a dummy catalyst that does not substantially support a catalyst.

The deterioration judging means 13 judges the deterioration of the catalyst based on the outlet gas temperature detected by the outlet gas temperature detecting means 11 and the dummy catalyst exhaust gas temperature estimated by the dummy catalyst exhaust gas temperature estimating means 12. It is a means to do. The inlet 21 of the catalytic converter 2 is connected to the internal combustion engine body 7 by an inlet pipe 41, while the outlet 22 of the catalytic converter 2 is connected to a muffler by an outlet pipe 42. The outlet gas temperature detecting means 11 is connected to the outlet 22 of the catalytic converter 2.
10 to 20 cm from the outlet pipe 42.

The deterioration determining means 13 determines the presence or absence of catalyst deterioration as follows. That is, when there is no difference between the outlet gas temperature detected by the outlet gas temperature detecting means 11 and the dummy catalyst exhaust gas temperature estimated by the dummy catalyst exhaust gas temperature estimating means 12, it is determined that the catalyst is in a deteriorated state. I do. On the other hand, if there is a sufficient difference between the outlet gas temperature and the dummy catalyst exhaust gas temperature, it is determined that the catalyst has not deteriorated. Note that the deterioration determination means 12 is configured by an algorithm in a digital computer.

The dummy catalyst exhaust gas temperature estimating means 12
Estimates the dummy catalyst exhaust gas temperature based on the engine operation information of the internal combustion engine from the engine control computer 3. In other words, the dummy catalyst exhaust gas temperature estimating means 12 is a digital computer that divides into a plurality of layers and calculates a neural network composed of an algorithm for performing a plurality of nonlinear calculations in each layer.

As the engine operation information, the engine speed, cooling water temperature, fuel injection amount, and torque are used. In addition, in the case where a nitrogen oxide reduction catalyst is used in a diesel engine, information on the amount of an exhaust gas purification reducing agent to be added is also added. Then, based on the engine operation information, the dummy catalyst exhaust gas temperature is estimated using the exhaust gas temperature data measured in advance by experiments.

FIG. 2 shows a flowchart of a concrete deterioration judgment in the catalyst deterioration judgment apparatus 1 of the present embodiment. The start of this flowchart is executed simultaneously with the start of the internal combustion engine. First, the start bit STbit is set to 1 in Step 101. Note that Step 1 in FIG.
01 to Step 118 are represented as S101 to S118.

Subsequent to S101, the engine control computer 3 uses the engine control computer 3 to obtain intake air amount Ga, rotation speed nr, cooling water temperature Tw, fuel injection amount Fin,
The catalyst outlet temperature Tout is measured from the torque TR by the outlet gas temperature detecting means 11 and the measured value is taken in (S10).
2). In a diesel engine, the injection amount Fad of the purifying agent for exhaust gas purification may be measured.

Next, the ST bit is checked (S103). S
If Tbit is 1, this is the first calculation after the start of the engine, so the initial outlet gas temperature Tout _n-1 is determined (S10).
4). In determining Tout _n-1 , the cooling water temperature Tw is used, and is determined using the map 5 shown in FIG.

In this map 5, when Tw is lower than 25 ° C., it is determined that a sufficient time has elapsed since the last stop of the engine, and it is assumed that the initial exhaust gas temperature is the same as that value and Tout _n−1 = 25 ° C. If Tw> 70 ° C., it is assumed that not much time has elapsed since the last stop of the engine, and Tout _n−1 is an estimated value Tout _old of the last outlet gas temperature during the previous operation. Also, 25 ° C ≦ Tw ≦ 70
In the case of ° C., it is determined according to Map 5 in FIG.

After Tout _n-1 is determined, STbit is reset to 0 (S105). Next, the change rate ΔTout of the dummy catalyst exhaust gas temperature is estimated by the dummy catalyst exhaust gas temperature estimating means 12 (S106). This dummy catalyst exhaust gas temperature estimating means 12 is constituted by the neural network 6, and as shown in FIG. 4, of the data taken in S102, a factor affecting the change in the outlet gas temperature from the dummy catalyst is input. It is input to the element 61 of the layer. Each element 61
Each element 61 performs the operation shown in FIG. 5 and transmits the operation result to the next element 61.

That is, in the element 61, FIG.
As shown in, (for input layer input value) output value of the element 610 of the preceding layer seek _{y i} sum but multiplied by the weight _{w i} to X (=? W _i y _i). Then, the sum X
Is input to the sigmoid function shown in Expression 1, and the calculated value Y is used as the output of the element 61.

[0034]

## EQU1 ## Y = 1 / (1 + exp- (X-.theta.))

Here, θ is a threshold value. Then, the output value of the output layer element is set to ΔTout. in this case,
The input value and the output value may be normalized from 0 to 1 as necessary. It is necessary to adjust the weight w and the threshold value θ so that the neural network 6 outputs a correct output value.

This adjustment is called learning. Several learning methods have already been proposed, but here the most common backpropagation methods (Rumelhart, DH, et al., Lear
ningRepresentation by Back-propagation Errors, Natu
re, Vol.322 (1986), p.533).

That is, the learning of the neural network 6 is performed as follows. First, the exhaust gas temperature under various operating conditions is measured using only a base material having the same size as the catalytic converter 1 and not carrying a catalyst, that is, a dummy catalyst. The neural network 6 is trained based on the obtained data by the back vacation method.

The neural network 6 thus obtained is incorporated in the dummy catalyst exhaust gas temperature estimating means 12. Using ΔTout estimated by the dummy catalyst exhaust gas temperature estimating means 12, the catalyst outlet gas temperature Tout is updated from Expression 2 in the next S 107.

[0039]

## EQU2 ## Tout _n = Tout _n-1 + △ Tout

Next, Tout measured by the outlet gas temperature detecting means 11 is compared with Tout _n obtained by the above equation (2). First, it is determined whether or not the fuel has been injected by the fuel injection amount Fin.
Is determined (S109). If Fin = 0, the reductant injection amount Fad for purifying exhaust gas is further determined. If Fad is also 0, no fuel is supplied to the catalytic converter, and the process proceeds to the end of determination (S118).

[0041] When any of Fin or Fad is not 0, the absolute value of the difference between Tout and Tout _n is calculated in S111. If this value is greater than the preset value α, the catalyst is ready to burn the supplied fuel,
It has not deteriorated.

Therefore, in step S113, the counter nOK is incremented by one. When the difference between Tout and Tout _n is small conversely, the fuel in the catalytic means that does not burn, so that the catalyst has deteriorated. In that case, the counter nBAD is incremented by one in S112. In S114, when the nOK counter becomes larger than the separately set threshold value β, it is determined that the catalyst can be sufficiently activated, so that nOK and nBAD are reset to 0 in S115. .

In step S116, the value of the counter nBAD is evaluated, and if the value exceeds a separately set threshold value γ, S
At 117, the deterioration of the catalyst is displayed and a warning is issued to the driver.
In S118, a series of determinations is ended, and the process returns to S102 to determine the deterioration again. In this example, the deterioration of the catalyst is determined by repeating the above.

As described above, the catalyst deterioration determination device 1 estimates the temperature of the exhaust gas of the dummy catalyst based on the engine operation information. The catalyst outlet gas temperature is detected by the outlet gas temperature detecting means 11. Then, catalyst deterioration is determined by comparing the estimated dummy catalyst exhaust gas temperature with the detected outlet gas temperature.

That is, when the active state of the catalyst is sufficient, the temperature of the exhaust gas rises due to the combustion of the hydrocarbon entering the catalyst. However, as the catalyst deteriorates, hydrocarbons do not burn,
The exhaust gas temperature also does not rise. Therefore, when the activity of the catalyst is sufficient, there is a difference between the outlet gas temperature and the temperature of the exhaust gas of the dummy catalyst. It is about the same as the catalyst exhaust gas temperature. Therefore, the deterioration of the catalyst is determined based on the temperature difference.

Next, the effect of this embodiment will be described. The catalyst deterioration determination device 1 has a dummy catalyst exhaust gas temperature estimating means 12 for estimating a dummy catalyst exhaust gas temperature which is an outlet gas temperature when the catalyst converter 2 does not support a catalyst. Therefore, in estimating the temperature of the exhaust gas of the dummy catalyst, it is not necessary to consider the heat of reaction caused by the catalytic reaction, which is difficult to accurately estimate. Therefore, it is possible to easily and accurately estimate the temperature of the exhaust gas of the dummy catalyst. Therefore, catalyst deterioration can be easily and accurately determined.

The temperature of the exhaust gas of the dummy catalyst is estimated by estimating the temperature of the outlet gas of the catalytic converter 2 compared with the case of estimating the temperature in the catalytic converter 2.
An accurate estimation can be made. This is because the exhaust gas that has passed through the entirety of the catalytic converter 2 passes through the outlet 21 of the catalytic converter 2 in a mixed manner, so that there is little variation. Similarly, an accurate measured value of the outlet gas temperature detected by the outlet gas temperature detecting means 12 can be obtained. Therefore, the catalyst deterioration can be easily and accurately determined.

As described above, according to the present embodiment, it is possible to provide a catalyst deterioration determination device capable of easily and accurately determining catalyst deterioration.

Embodiment 2 As shown in FIG. 6, this embodiment employs an inlet gas temperature detecting means 14.
This is an example of the catalyst deterioration determination device 102 in which a thermometer is installed in the inlet pipe 41. In the catalyst deterioration determination device 102, the temperature of the inlet gas at the catalyst inlet is measured by a thermometer.

In this embodiment, the inlet gas temperature detected by the inlet gas temperature detecting means 14 is input to the dummy catalyst exhaust gas temperature estimating means 12 (FIG. 6). The dummy catalyst exhaust gas temperature estimating means 12 estimates the dummy catalyst exhaust gas temperature using the catalyst inlet gas temperature in addition to the data used in the first embodiment. The inlet gas temperature is measured by the algorithm shown in FIG. 2 in S102 in FIG. Other configurations are the same as those of the first embodiment.

In this embodiment, the inlet gas temperature is directly measured by the inlet gas temperature detecting means 14. Therefore, an estimation error does not occur, and the inlet gas temperature can be obtained with high accuracy. As a result, as shown in FIG. 7, the temperature of the exhaust gas of the dummy catalyst can be estimated with higher accuracy.
The deterioration determination accuracy is further improved.

In FIG. 7, T ₀ represents a value obtained by actually measuring the outlet gas temperature using a dummy catalyst.
₁ represents a dummy catalyst exhaust gas temperature estimated by embodiment 1, also, T ₂ represents a dummy catalyst exhaust gas temperature estimated by the present embodiment. In addition, the third embodiment has the same functions and effects as the first embodiment.

Embodiment 3 As shown in FIG. 8, the present embodiment is directed to
This is an example of a catalyst deterioration determination device 103 in which a hydrocarbon detector 15 for measuring in is installed in an inlet pipe 41 of an inlet 21 of a catalytic converter 2. In this case, the amount of hydrocarbon entering the catalytic converter 2 is directly measured. Then, the result is input to the deterioration determining means 13 (FIG. 8). The catalyst degradation determination algorithm is different from that of the first embodiment in that the portion indicated by a broken line S108 in FIG. 2 is changed to the determination shown in FIG.

That is, if the measured HCin is 0, the process proceeds to S118, and if the measured HCin is other than 0, the process proceeds to S118.
The process proceeds to 111 and proceeds to the deterioration determination algorithm (FIG. 9). H
The measurement of Cin is measured in S102 in the algorithm of FIG. Other configurations are the same as those of the first embodiment.

In the case of this embodiment, the hydrocarbon detecting means 1
5 directly measures the amount of hydrocarbons entering the catalytic converter 2. Therefore, the amount of carbonized carbon entering the catalytic converter 2 can be accurately grasped. This makes it easy and accurate to determine whether or not to perform the deterioration determination. Accordingly, the accuracy of the deterioration determination is also improved.
In addition, the third embodiment has the same functions and effects as the first embodiment. The hydrocarbon amount can be directly measured as described above, but can also be estimated from the engine operation information.

Fourth Embodiment As shown in FIG. 10, this embodiment is an example of a catalyst deterioration judging device 104 to which environmental information detecting means 16 for detecting environmental information around the vehicle and the catalytic converter 2 is added. The data measured by the environment information detecting means 16 is sent to the dummy catalyst exhaust gas temperature estimating means 12 (FIG. 10).

The environmental information detecting means 16 measures the outside temperature Tam around the vehicle, the wind speed V around the catalyst, and the like. The measured data is used as the dummy catalyst exhaust gas temperature estimating means 12.
Sent to Here, first, the initial outlet gas temperature Tout _n-1 is estimated in S104 in FIG. In the first embodiment, the cooling water temperature is compared with 25 ° C., but in the present embodiment, the cooling water temperature Tw is compared with the outside air temperature Tam. Then, Tout _n-1 is determined from the difference between the two using the map 50 shown in FIG.

In this map 50, when the difference between Tw and Tam is small, it is determined that a sufficient time has elapsed since the last engine stop, and the temperature of the catalyst is equal to the outside air temperature, and the initial outlet gas temperature Tout is set to the same level as the outside air temperature.
_{Let n-1} = Tam. If the difference between Tw and Tam is large,
It is assumed that not much time has elapsed since the last engine stop, and Tout _n-1 is the last estimated temperature Tout at the previous operation.
_{Using the old} and Tam, it is determined by the map 50 of FIG. The outside air temperature Tam and the wind speed V around the catalytic converter 2 are input to the neural network 6 of the dummy catalyst exhaust gas temperature estimating means 12. Other configurations are the same as those of the first embodiment.

The catalyst deterioration judging device 104 of this embodiment uses the outside air temperature to estimate the temperature of the dummy catalyst exhaust gas at the time of starting the engine, so that it is possible to estimate the temperature of the dummy catalyst exhaust gas with high accuracy. . For example, the outlet gas temperature of the catalytic converter 2 that appears immediately after the start of the engine differs between summer and winter. In the present embodiment, this difference can be treated separately, and the accuracy of estimation of the temperature of the exhaust gas of the dummy catalyst can be improved.

Further, in the catalyst deterioration judging device 104,
The ambient temperature and the wind speed around the catalyst can also be input to the dummy catalyst exhaust gas temperature estimating means 12 as information of the dummy catalyst exhaust gas temperature estimation. Thus, it is possible to accurately estimate the temperature of the exhaust gas of the dummy catalyst in consideration of heat conduction from the catalytic converter 2 to the surrounding environment. Other, Embodiment 1
It has the same function and effect as described above. The above environmental information can be directly measured, but can also be estimated from information such as a speedometer.

Fifth Embodiment As shown in FIG. 12, in this embodiment, the flow rate measuring means 17 for measuring the flow rate of the exhaust gas entering the catalytic converter 2 is installed at the inlet pipe 41 of the inlet 21 of the catalytic converter 2 to determine the deterioration of the catalyst. It is an example of the device 105.

In the catalyst deterioration determination device 105,
The flow rate of the exhaust gas entering the catalytic converter 2 is directly measured by the flow rate measuring means 17. Then, the result is input to the dummy catalyst exhaust gas temperature estimating means 12. That is, the dummy catalyst exhaust gas temperature estimating means 12 estimates the dummy catalyst exhaust gas temperature using the exhaust gas flow rate in addition to the data in the first embodiment. Fig. 2 Exhaust gas flow rate
Is measured in S102 in the algorithm of (1).

In this embodiment, the flow rate of the exhaust gas at the inlet 21 of the catalytic converter 2 is directly measured by the flow rate measuring means 17, so that the gas flow rate at the inlet 21 can be obtained with high accuracy without an estimation error. . As a result, the temperature of the dummy catalyst exhaust gas can be estimated with higher accuracy, and the accuracy of the deterioration determination can be further improved. In addition, the third embodiment has the same functions and effects as the first embodiment.

In the above-described embodiment, no consideration has been given to whether or not deterioration is to be determined based on the catalyst outlet gas temperature. However, in general, a catalyst is characterized in that a reaction does not occur unless the temperature exceeds a certain activation temperature. Therefore, when the catalyst temperature is low immediately after the start of the engine, even if the catalyst has not deteriorated, a catalytic reaction may not occur. In order to solve this problem, it is also possible to examine the value of the outlet gas temperature and to make an algorithm so that the deterioration is determined only when the temperature is higher than a certain threshold value.

In the above embodiment, each detecting means is used independently. However, it is also possible to use a plurality of them at the same time, and it is possible to estimate the dummy catalyst exhaust gas temperature with higher accuracy than this. As a result, the deterioration determination accuracy is further improved.

[0066]

As described above, according to the present invention, it is possible to provide a catalyst deterioration determining apparatus capable of easily and accurately determining catalyst deterioration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a catalyst deterioration determination device according to a first embodiment.

FIG. 2 is a flowchart of catalyst deterioration determination according to the first embodiment.

FIG. 3 is a map diagram for determining an initial outlet gas temperature in the first embodiment.

FIG. 4 is a conceptual diagram of a neural network according to the first embodiment.

FIG. 5 is an explanatory diagram of an operation in each element of the neural network according to the first embodiment.

FIG. 6 is a configuration diagram of a catalyst deterioration determination device according to a second embodiment.

FIG. 7 is a diagram showing a result of estimation by a dummy catalyst exhaust gas temperature estimating means in the second embodiment.

FIG. 8 is a configuration diagram of a catalyst deterioration determination device according to a third embodiment.

FIG. 9 is a diagram illustrating a replacement part of S108 in FIG. 2 in a case where a hydrocarbon detection unit is used in the third embodiment.

FIG. 10 is a configuration diagram of a catalyst deterioration determination device according to a fourth embodiment.

FIG. 11 is a map diagram for determining an initial outlet gas temperature in a fourth embodiment.

FIG. 12 is a configuration diagram of a catalyst deterioration determination device according to a fifth embodiment.

[Explanation of symbols]

1,102,103,104,105. . . 10. catalyst deterioration determination device, . . 11. outlet gas temperature detecting means; . . 12. Dummy catalyst exhaust gas temperature estimating means; . . 13. deterioration determination means; . . 14. inlet gas temperature detecting means; . . Hydrocarbon detection means, 16. . . Environment information detecting means, 17. . . Flow rate measuring means, 2. . . Catalytic converter, 21. . . Entrance, 22. . . Exit, 3 . . Computer for engine control, 41. . . Inlet piping, 42. . . Outlet piping, 5. . . Map, 6. . . Neural network,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiko Asano 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside of Toyota Central Research Laboratory Co., Ltd. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Koji Yokota 41, Ochicho, Oku-cho, Nagakute-cho, Aichi-gun, Aichi Prefecture 1 Toyota Toyota Central Research Laboratory Co., Ltd. (72) Inventor Kondo Lighting Aichi Prefecture 1 41 Toyota Central Research Institute, Nagakute-cho, Nagakute-machi, Aichi-gun Toyota Central Research Institute, Inc. (72) Inventor Kazuya Kibe 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G084 AA01 DA25 DA27 EA04 EA08 EA11 EB08 EB25 EC04 FA07 FA13 FA20 FA27 FA28 FA32 FA33 3G091 AA02 AA17 AA18 AB01 BA33 DB13 DC02 DC06 EA01 EA02 EA05 EA08 EA 16 EA18 FC02 HA11 HA36 HA37

Claims (4)

[Claims] 1. A catalyst deterioration judging device for judging deterioration of a catalyst of a catalytic converter provided in an exhaust system of an internal combustion engine, the catalyst deterioration judging device comprising an outlet gas detecting an outlet gas temperature of the catalytic converter. A temperature detecting means, a dummy catalyst exhaust gas temperature estimating means for estimating a dummy catalyst exhaust gas temperature shown below, and an outlet gas temperature detected by the outlet gas temperature detecting means and a dummy estimated by the dummy catalyst exhaust gas temperature estimating means. A deterioration determining means for determining deterioration of the catalyst based on the temperature of the catalyst exhaust gas, wherein the temperature of the dummy catalyst exhaust gas is determined assuming that the catalytic converter is a dummy catalyst substantially not carrying a catalyst. A catalyst deterioration determination device, characterized in that the temperature is the outlet gas temperature. 2. The catalyst deterioration judging device according to claim 1, wherein said dummy catalyst exhaust gas temperature estimating means is constituted by a neural network having a nonlinear conversion function and a learning function. 3. The catalyst deterioration judging device according to claim 1, further comprising an inlet gas temperature detecting means for detecting an inlet gas temperature entering the catalytic converter, and wherein the dummy catalyst exhaust gas temperature estimating means is provided. And a catalyst deterioration determining device for estimating a dummy catalyst exhaust gas temperature using the inlet gas temperature detected by the inlet gas temperature detecting means. 4. The catalyst deterioration judging device according to claim 1, further comprising an inlet gas temperature estimating means for estimating an inlet gas temperature entering the catalytic converter, and wherein the dummy catalyst exhaust gas temperature estimating means is provided. A catalyst deterioration determining device for estimating a dummy catalyst exhaust gas temperature using the inlet gas temperature estimated by the inlet gas temperature estimating means.