JP2002339790A - Catalyst deterioration detector for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst deterioration detector capable of comprehensively determining the deterioration of a catalyst by considering various deterioration forms. SOLUTION: This catalyst deterioration detector for an internal combustion engine is characterized by comprising a catalyst installed in an exhaust system of the internal combustion engine, a means for detecting the temperature of the catalyst, a means for detecting the space velocity of an exhaust gas, a means for detecting deterioration parameters of the catalyst and a catalyst deterioration degree detection means for detecting the deterioration degree of the catalyst based on the plural deterioration parameters detected in plural conditions different in space velocity and catalyst temperature. According to this application, the deterioration degree of the catalyst can be comprehensively determined depending on various deterioration forms. The catalyst deterioration detector is so structures that the deterioration degree of the catalyst can be obtained by respectively weighting the plural deterioration parameters of the catalyst and by adding them together, and hence the deterioration degree of the catalyst can be comprehensively determined by one value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst deterioration detecting device for an internal combustion engine for detecting the deterioration of a catalyst provided in an exhaust system of an internal combustion engine such as an automobile for purifying exhaust gas.

[0002]

2. Description of the Related Art Japanese Patent No. 2,843,879 discloses a catalyst deterioration detecting device which uses a catalyst oxygen storage capacity to perform accurate catalyst deterioration determination based on the output of a relatively stable catalyst downstream O2 sensor. Has been proposed. In this catalyst deterioration detection device, the air-fuel ratio is feedback-controlled by the output of the downstream O2 sensor, and the time until the output of the downstream O2 sensor is inverted from rich to lean or from lean to rich is stored in the oxygen storage of the catalyst. Detected as ability.

[0003]

In the prior art, detection of deterioration of the catalyst is performed only when the engine is in a predetermined operating state. That is, the catalyst deterioration detection process is performed only when the engine is operating in a predetermined state in order to accurately detect the deterioration of the catalyst.

[0004] However, the actual purifying ability of the catalyst is as follows.
It does not always change according to the catalyst temperature and the space velocity of the exhaust gas. Further, the degree of reduction of the purification performance of the catalyst actually provided in the exhaust pipe of the engine may vary depending on the temperature and the operating state.

As described above, since the prior art catalyst deterioration detecting device judges the deterioration of the catalyst only in a single state, the overall deterioration of the catalyst is not accurately reflected.

Accordingly, it is an object of the present invention to provide a catalyst deterioration detecting device which comprehensively judges the deterioration of a catalyst in consideration of various deterioration modes.

[0007]

In order to solve the above-mentioned problems, a catalyst deterioration detecting apparatus for an internal combustion engine according to the present invention comprises a catalyst provided in an exhaust system of an internal combustion engine, and means for detecting a temperature of the catalyst. Means for detecting a space velocity of exhaust gas, means for detecting a deterioration parameter of the catalyst, and a degree of deterioration of the catalyst based on a plurality of deterioration parameters detected under a plurality of conditions different in space velocity and catalyst temperature. And a catalyst deterioration degree detecting means for detecting.

According to the present invention, the degree of deterioration of the catalyst can be comprehensively determined according to various types of deterioration.

According to one embodiment of the present invention, the catalyst deterioration detecting device is configured to obtain the degree of deterioration of the catalyst by weighting and adding the deterioration parameters of the plurality of catalysts.

According to this embodiment, the degree of catalyst deterioration can be comprehensively determined by one value from the catalyst deterioration parameters measured under a plurality of conditions.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic diagram showing a catalyst deterioration detection device for an internal combustion engine according to an embodiment of the present invention. FIG.
Shows a schematic diagram of the engine 1 and its control device. The intake pipe 3 of the engine 1 is provided with a throttle valve opening sensor (θTH).
And a throttle valve 9 connected to the throttle valve 11. The throttle valve opening sensor 11 outputs an electric signal according to the opening of the throttle valve 9 and outputs the output to an electronic control unit (hereinafter referred to as “EC
U ”) 31). The intake pipe 3 has an intake pipe absolute pressure sensor (PBA) 13 for detecting the pressure in the intake pipe on the downstream side of the throttle valve 9, and its output is EC.
Provided to U31.

The main body of the engine 1 has an engine speed sensor (NE) 21 for detecting the speed of the engine 1. The NE sensor 21 provides an output pulse to the ECU 31 every time the crankshaft of the engine 1 rotates 180 degrees.

The engine 1 includes various sensors in addition to the NE sensor 21. The outputs of these sensors are
The ECU 31 is used to detect the operating state of the engine. For example, as such a sensor, an engine coolant temperature (T
W) sensors. In this embodiment, such a plurality of sensors are collectively shown as a sensor 19.

An exhaust pipe 5 provided in the engine 1 is provided with a three-way catalyst 23 for purifying exhaust gas. An upstream air-fuel ratio sensor 17 is provided between the engine 1 and the catalyst 23 in the exhaust pipe 5. This sensor 17 detects the air-fuel ratio of the air-fuel mixture in the engine 1. Sensor 17
May be a linear air-fuel ratio sensor that detects the air-fuel ratio over the entire area according to the model of the engine 1, or may be an O2 sensor that changes the level on and off from the stoichiometric air-fuel ratio. This detection signal is sent to the ECU 31 and used to control the air-fuel ratio of the engine 1. Catalyst 23
An O2 sensor 25 is provided in the exhaust pipe 5 on the downstream side. The sensor 25 detects the oxygen concentration of the exhaust gas passing through the catalyst 23.

Input signals from various sensors are passed to an input circuit of the ECU 31. The input circuit shapes an input signal waveform, corrects a voltage level to a predetermined level, and converts an analog signal value to a digital signal value. The CPU processes the converted digital signal, executes an operation according to a program stored in the ROM, and generates a control signal to be sent to an actuator of each part of the vehicle. This control signal is sent to an output circuit, which sends a control signal to the fuel injector 15 and other actuators.

The ECU 31 executes a calculation for controlling each part of the engine 1, a read-only memory (ROM) for storing a program for controlling each part of the engine and various data, and a work of calculation by the CPU. A random access memory (RAM) for providing an area and temporarily storing data sent from each engine and control signals sent to each engine; an input circuit for receiving data sent from each engine; It has an output circuit to send.

The program stored in the ECU 31 is stored as a plurality of modules, and the program for determining catalyst deterioration according to the present invention is included in one or more of these modules. Also,
Various data used for the calculation are stored in the ROM as a table. The ROM may be a rewritable ROM such as an EEPROM.

In FIG. 1, some of the functions processed by the ECU 31 based on such a hardware configuration are shown by functional blocks. The ECU 31 controls the engine
It includes functional blocks of a fuel injection control unit 61, an ignition timing control unit 63, an operation state detection unit 65, and an air-fuel ratio setting unit 67.

The operating state detecting section 65 is based on the signals output from the various sensors shown in FIG. 1, and controls the engine 1 represented by parameters such as vehicle speed VP, engine speed NE, engine coolant temperature TW, and outside temperature TA. Detects operating conditions. For example, the driving state detection unit 65 counts the pulses output from the wheel speed sensors and detects the vehicle speed VP.
In addition, the operating state detection unit 65 counts the pulses of the signal output from the NE sensor, and detects the engine speed NE.

The air-fuel ratio setting section 67 includes an operating state detecting section 65
, And sets target air-fuel ratios according to various processes. The ignition timing control unit 63 sends a signal for controlling the ignition timing based on the operating state of the engine, the target air-fuel ratio, and the like, and controls the ignition timing of the ignition plug. The fuel injection control unit 61 calculates the fuel injection time according to the operating state of the engine, the target air-fuel ratio, and the like, and controls the fuel injection device 15.

The ECU 31 performs various engine operation states in an air-fuel ratio feedback control region or a plurality of specific operation regions in which the air-fuel ratio feedback control is not performed (hereinafter referred to as "open loop control region") based on the various engine parameter signals. The TD is determined based on the following equation 1 in accordance with the determined engine operating state.
The fuel injection time TOUT of the fuel injection device 15 synchronized with the C signal pulse is calculated.

[0022]

TOUT = Ti × KO2 × KLS × K1 + K2

Here, Ti is a basic fuel injection time of the fuel injection device 15, and is determined according to the engine speed NE and the intake pipe absolute pressure PBA.

KO2 is an air-fuel ratio correction coefficient (hereinafter referred to as a "correction coefficient"), and is based on the oxygen concentration in the exhaust gas detected by the upstream air-fuel ratio sensor 17 and the downstream O2 sensor 25 during the air-fuel ratio feedback control. Asked
Further, in the open loop control region, the value is set to a value corresponding to each operation region.

The KLS is set to a predetermined value (for example, 0.95) smaller than 1.0 when the engine 1 is in the lean region or the fuel cut region, that is, the predetermined deceleration operation region, of the open loop control region. Leaning coefficient.

K1 and K2 are other correction coefficients and correction variables calculated according to various engine parameter signals, respectively, so that various characteristics such as fuel consumption characteristics and engine acceleration characteristics can be optimized according to the engine operating state. Is determined to be a predetermined value.

The ECU 31 controls the fuel injection device based on the fuel injection time TOUT obtained as described above.

The catalyst deterioration detecting device according to the present invention determines the overall degree of deterioration of the catalyst 23 based on the above-mentioned operating condition parameters. The catalyst deterioration detecting device according to the present invention includes a catalyst temperature detecting means 30, a space velocity detecting means 29, a measurement condition judging means 24, and a catalyst deterioration detecting means 26.

The catalyst temperature detecting means 30 detects the temperature of the catalyst 23, and the space velocity detecting means 29 detects the amount of exhaust gas passing through the catalyst 29 per unit time (the space velocity S
V) is detected. The measurement condition determination means 24 determines measurement conditions for detecting catalyst deterioration based on the detected catalyst temperature and space velocity. The catalyst deterioration detecting means 26 detects the degree of deterioration of the catalyst according to the measurement conditions determined by the measurement condition determining means 24. The overall deterioration degree of the catalyst 23 is determined based on a plurality of deterioration degrees detected under a plurality of measurement conditions.

Hereinafter, the catalyst deterioration detection according to the present invention will be described in more detail.

FIG. 2 is a diagram in which the amounts of harmful components (HC, CO, NOx) contained in the exhaust gas passing through the catalyst are plotted with respect to the elapsed time after starting the engine, and the degree of deterioration differs at low temperatures. The properties of the three catalysts are shown. These catalysts differ only in the purifying ability at low temperatures, and have almost the same purifying ability after the temperature of the catalyst reaches the activation temperature.

Reference numeral 32 in FIG. 2 indicates a catalyst that has relatively little deterioration at low temperatures, and reference numeral 35 indicates a catalyst that has relatively large deterioration at low temperatures. Reference number 33
Indicates a catalyst having a degree of deterioration between the catalyst of reference numeral 32 and the reference numeral 35.

Usually, the temperature of the catalyst is gradually increased by exhaust gas discharged after the engine is started. Therefore, the elapsed time on the horizontal axis in FIG. 2 corresponds to a change in the temperature of the catalyst. Immediately after the start of the engine, since the temperature of the catalyst has not reached the activation temperature, a catalytic reaction does not occur, and the amount of harmful components in the exhaust gas passing through the catalyst rapidly increases. At this point, the temperature of the catalyst is lower than the catalyst activation temperature,
There is a large difference in the amount of harmful components contained in the exhaust gas downstream of each catalyst. The difference between the catalysts reaches a maximum when the amount of the harmful component reaches a peak (at the point a in FIG. 2). The harmful components in the exhaust gas downstream of each catalyst begin to decrease as the catalyst is gradually warmed by the exhaust gas, and after the catalyst has completely reached its activation temperature (at time c in FIG. 2), it is substantially practical. The difference disappears.

That is, FIG. 2 shows that there are catalysts having different purifying capacities at low temperatures even if the purifying capacities after the catalyst activation temperature are the same. As a result, only a single measurement condition is required. Indicates that it is difficult to determine the deterioration of the catalyst. Therefore, the catalyst deterioration detection device of the present invention detects the degree of deterioration of the catalyst before and after the catalyst is warmed up.

Further, the catalyst deterioration detecting device of the present invention considers not only the catalyst temperature but also the amount of exhaust gas passing through the catalyst per unit time (space velocity SV) as a measurement condition. Hereinafter, the change in the degree of deterioration of the catalyst with respect to the space velocity SV will be described in detail with reference to FIG.

In FIG. 3, the horizontal axis represents the amount of exhaust gas passing through the catalyst per unit time (space velocity SV), and the vertical axis represents the amount of harmful components contained in the exhaust gas passing through the catalyst.

In this figure, the characteristics of three catalysts having different degrees of deterioration are shown with respect to the space velocity. Reference numeral 59 in FIG. 3 indicates a catalyst with relatively little deterioration, and reference numeral 57 indicates a catalyst with relatively large deterioration. Reference numeral 58 is replaced by reference numeral 57 and reference numeral 59.
5 shows a catalyst having a degree of deterioration between the two.

FIG. 3 shows that when the space velocity is relatively low (a in the figure), the emission concentration increases in proportion to the degree of deterioration, but when the space velocity is relatively high (b in the figure), The emission concentration increases exponentially with the degree of deterioration.

Therefore, in the catalyst deterioration detecting device of the present invention, when the engine is under a high load (when the amount of exhaust gas per unit time is large) and when the engine is under a low load (when the amount of exhaust gas per unit time is small) And) to detect the deterioration parameters of the catalyst.

As a result, the catalyst deterioration detecting device of the present invention has the following advantages. 1) When the space velocity of the exhaust gas is low before the catalyst is warmed up, and 2) When the space velocity of the exhaust gas is low after the catalyst is warmed up. When the catalyst is warmed up, and when the space velocity of the exhaust gas is high after the catalyst is warmed up, the deterioration parameter of the catalyst is detected in three states. The deterioration parameters of the catalyst detected in the three types of states are respectively weighted and added to one value, and the degree of deterioration of the catalyst is comprehensively determined.

In this embodiment, the overall degree of deterioration of the catalyst is determined based only on the three types of states. However, a larger number of arbitrary states are set, and the catalyst detected in a plurality of the set states is determined. The overall degree of catalyst deterioration may be determined on the basis of the deterioration parameter.

FIG. 4 shows one embodiment of a flowchart for detecting catalyst deterioration according to the present invention. To give an overview of these processes, first, the engine is branched into a high load and a low load by detecting the engine speed (NE) and the intake pipe pressure (PBA), and the catalyst temperature is estimated after the branch. Thus, the temperature is branched at a low temperature and a high temperature to detect the deterioration parameters of the catalyst. After all catalyst deterioration parameters are detected under the set measurement conditions, the overall catalyst deterioration degree is determined based on the plurality of deterioration parameters.

In this flowchart, since the amount of exhaust gas of the engine 1 corresponds to the amount of intake air per unit time, the space velocity is not directly measured, and the absolute pressure PB in the intake pipe is not measured.
A and the value of the engine speed NE are used instead. That is, as shown in FIG. 5, a range 71 surrounded by the engine speed NE from L1 to H1 and the intake pipe absolute pressure PBA from L1 to H1 corresponds to the low load state, and the range from L2 to H2 of the engine speed NE. A range 73 surrounded by L2 and H2 of the intake pipe absolute pressure PBA corresponds to a high load state.
In the low load range 71, the temperature of the catalyst is further estimated, and the temperature is branched at low temperature and high temperature to detect the deterioration parameter of the catalyst in each state.

In this embodiment, the deterioration parameter of the catalyst is detected based on the oxygen storage capacity of the catalyst.
Techniques for measuring the oxygen storage capacity of the catalyst are similar to those used in the prior art. That is, the air-fuel ratio is feedback-controlled using the downstream O2 sensor 25 shown in FIG. 1, and the value of the inversion cycle of the downstream O2 sensor 25 at that time is used as a parameter representing the oxygen storage capacity.

In this case, if the purification rate of the catalyst is high (when the catalyst is not deteriorated), the cycle in which the output of the downstream O2 sensor 25 is inverted is when the purification rate of the catalyst is low (when the catalyst is deteriorated). It is longer than that. That is, there is a positive correlation between the oxygen storage capacity of the catalyst and the purification capacity (rate) of the catalyst.

In this embodiment, the deterioration parameter of the three-way catalyst is detected based on the oxygen storage capacity. However, the present invention is not limited to such an embodiment, and the purification rate is obtained by directly detecting the amount of harmful components. Other arbitrary techniques can be applied.

The processing for judging catalyst deterioration shown in FIG.
The process is executed every predetermined time (for example, 10 msec) at 31. First, at step 103, it is determined whether or not comprehensive determination of deterioration of the catalyst has been completed. If the overall catalyst deterioration determination has already been performed, the process proceeds to step 139, and the catalyst deterioration determination process ends. If the overall catalyst deterioration determination has not yet been performed, step 1
Go to 05.

In step 105, it is determined whether or not the current engine speed NE is within a predetermined low speed range (NEMONL1 to NEMONH1). If the current engine speed NE is within the low speed range,
Proceeding to step 109, it is determined whether the engine is in a low load state. If the current engine speed NE
If is not within the low rotation range, proceed to step 113,
It is determined whether the engine is at a high speed.

In step 109, the current intake pipe absolute pressure PBA is set in a predetermined range (PBMONL1 to PBMONL1 to PBMONL1).
BMONH1) is determined. If the absolute pressure PBA is within this range, it is determined that the engine is in a low load state. If the absolute pressure PBA is not within this range, the routine proceeds to step 113, where it is determined whether or not the engine is at a high speed.

In step 111, the current catalyst temperature TC
It is determined whether the AT is in a predetermined temperature range. The temperature of the catalyst may be directly detected by installing a temperature sensor on the catalyst, or may be estimated from the operating state of the engine. The means for estimating the catalyst temperature from the operating state of the engine is a conventional technique and will not be described in detail here.

The temperature range determined in step 111 (TCATMONL1 <TCAT <TCATMONH
1) is a relatively low temperature below the activation temperature of the catalyst,
Generally, it is a temperature immediately after the engine is started and before warm-up.

In step 111, if the current catalyst temperature T
When it is determined that the CAT is within a predetermined temperature range (that is, when it is determined that the catalyst has not been warmed up),
Proceeding to step 121, catalyst degradation parameters are measured. That is, in step 121, the oxygen storage capacity of the catalyst before warm-up and in a state where the space velocity of the exhaust gas is low is detected. The oxygen storage capacity of the catalyst detected in step 121 is held in the ECU 31 as RESCAT1.

If the current catalyst temperature TC is
When it is determined that the AT is not within the predetermined temperature range (that is, when it is determined that the catalyst is not before the warm-up),
Proceeding to step 117, it is determined whether the catalyst has been warmed up.

In step 117, the current catalyst temperature TC
AT is set to a predetermined temperature range (TCATMONL2 <
By comparing TCAT <TCATMONH2), it is determined whether the catalyst has been warmed up. This predetermined temperature range is a relatively high temperature equal to or higher than the activation temperature at which the catalyst acts as a catalyst, and is generally a temperature after a sufficient time has passed since the engine was started and the engine was warmed up.

In step 117, if the current catalyst temperature T
When it is determined that the CAT is within a predetermined temperature range (that is, when it is determined that the catalyst has been warmed up),
Proceeding to step 123, the degradation parameters of the catalyst are measured. That is, in step 123, the oxygen storage capacity of the catalyst after the warm-up and in a state where the space velocity of the exhaust gas is low is detected. The oxygen storage capacity of the catalyst detected in step 123 is held in the ECU 31 as RESCAT2.

Next, detection of deterioration of the catalyst under a high load will be described. In this case, in step 105 after the catalyst deterioration detection process is started, the current engine speed NE is determined.
Is a predetermined low rotation range (NEMONL1 <NE
<NEMONH1), it is determined that step 113
Proceed to.

In step 113, the current engine speed NE is set to a predetermined high speed range (NEMONL2
<NE <NEMONH2) is determined. If the current engine speed NE is in the predetermined high speed range, the routine proceeds to step 115, where the current intake pipe absolute pressure PBA is set in the predetermined range (PBMON).
It is determined whether or not L2 <PBA <PBMONH2. If the absolute pressure PBA is within this range, it is determined that the engine is under a high load, and step 119 is performed.
Then, the temperature TCAT of the catalyst is estimated.

In step 119, the current catalyst temperature T
When the CAT is in a predetermined temperature range (TCATMONL2
<TCAT <TCATMONH2) is determined. If the current catalyst temperature TCAT is within this range, it is determined that the catalyst has already been warmed up, and the routine proceeds to step 125, where a deterioration parameter of the catalyst is detected.
That is, in step 125, the oxygen storage capacity of the catalyst after the warm-up and in a state where the exhaust gas has a high space velocity is detected. The oxygen storage capacity of the catalyst detected in step 125 is RESCAT3 as ECU3
It is held within 1.

In any of steps 121, 123, and 125, the process proceeds to step 127 after completion of each step. In step 127, it is determined whether the catalyst deterioration parameter has been detected under all the preset measurement conditions. That is, RESCAT1 to R
The degradation parameters of all catalysts up to ESCAT3 are EC
It is determined whether it is already stored in U.

If it is determined in step 127 that the deterioration parameters of all the catalysts have already been detected, the routine proceeds to step 131, where the overall deterioration parameter RES of the catalyst is determined.
The CAT is determined based on Equation 2.

[0061]

(Equation 2)

Here, α1, α2, and α3 are weighting coefficients of the deterioration parameters of the catalyst detected under the respective conditions, and the ratios may be changed according to the ratio of the operating range of the engine. For example, since the engine operating range in the state of the catalyst at the activation temperature or higher is generally wider than the engine operation area in the state of the catalyst at the activation temperature or lower, it is not preferable to add these with the same weight. Therefore, in this case, it is preferable that the weight of the deterioration parameter of the catalyst below the activation temperature is reduced and added.

After step 131, step 133
To the overall catalyst degradation parameter RESCAT
Is a predetermined catalyst deterioration determination reference value RESCAT
Compared to JUD. This deterioration determination reference value RESCAT
JUD is a value determined experimentally. If RESCAT is smaller than the deterioration determination reference value, the degree of deterioration of the catalyst is large, and it is determined that the catalyst is deteriorated (step 135). If RESCAT is larger than the deterioration determination reference value, the degree of deterioration of the catalyst is small, and it is determined that the catalyst has not deteriorated (step 137).

In this embodiment, the deterioration parameters of the catalyst are detected under three kinds of measurement conditions corresponding to the temperature and the space velocity of the catalyst, and the comprehensive deterioration parameters of the catalyst are obtained from the three kinds of deterioration parameters. Thus, the overall degree of deterioration of the catalyst can be determined by reflecting various types of deterioration of the catalyst.

Although the present invention has been described with reference to a specific embodiment, the present invention is not limited to such an embodiment, and various modifications that can be easily made by those skilled in the art are also included in the scope of the present invention. included.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a catalyst deterioration detection device according to the present invention.

FIG. 2 is a diagram showing characteristics of three catalysts having different degrees of deterioration at low temperatures.

FIG. 3 is a diagram showing three catalysts having different degrees of deterioration with respect to space velocity.

FIG. 4 is a flowchart of catalyst deterioration detection according to the present invention.

FIG. 5 is a diagram showing ranges of a high load and a low load at a space velocity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 5 Exhaust pipe 17 Upstream oxygen sensor 23 Three-way catalyst 25 Downstream O2 sensor 29 Space velocity detection unit 30 Catalyst temperature detection unit 24 Measurement condition judgment unit 26 Catalyst deterioration detection unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norihiko Suzuki 1-4-1 Chuo, Wako, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Hideki Uedahira 1-4-1, Chuo, Wako, Saitama No. F-term in Honda R & D Co., Ltd. (Reference) 3G084 BA03 BA05 BA09 BA13 BA16 BA24 CA02 CA03 CA04 DA27 EA02 EA04 EB01 EB08 FA00 FA02 FA05 FA10 FA11 FA20 FA26 FA29 FA33 FA38 3G091 AA02 AB03 BA33 EA00 EA01 EA18 EA18 EA18 EA34 EA39 FA04 FA13 FA14 FB02 FB03 HA36 HA37

Claims (2)

[Claims] A catalyst provided in an exhaust system of an internal combustion engine; a means for detecting a temperature of the catalyst; a means for detecting a space velocity of exhaust gas; a means for detecting a deterioration parameter of the catalyst; A catalyst deterioration detection device for an internal combustion engine, comprising: catalyst deterioration degree detecting means for detecting a degree of deterioration of a catalyst based on a plurality of deterioration parameters detected under a plurality of conditions having different speeds and catalyst temperatures. 2. The catalyst deterioration detecting device for an internal combustion engine according to claim 1, wherein the degree of deterioration of the catalyst is obtained by weighting and adding the deterioration parameters of the plurality of catalysts.