JP2004084528A - Device for detecting failure of supplying secondary air of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve accuracy for detecting failure of a secondary air introduction mechanism introducing secondary air in an exhaust passage for the purpose of activating a catalyst quickly. <P>SOLUTION: A fuel injection volume calculated and supplied on the basis of various operation parameters of an internal combustion engine 10 is reduced for correcting an air-fuel ratio immediately after the secondary air is stopped by a secondary air introduction mechanism 30.When a result detected by an A/F sensor 24 is leaner than a predetermined value, an introducing condition is still kept though the secondary air from the secondary air introduction mechanism 30 is made in a stop condition, so that the secondary air introduction mechanism 30 is judged as fail. Failure of the secondary air introduction mechanism 30 is judged using an A/F sensor value from the A/F sensor 24, so as to improve accuracy for detecting failures. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a secondary air supply abnormality detection device for an internal combustion engine that detects an abnormality when secondary air is supplied to activate a catalyst in an exhaust passage of the internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a prior art document related to a secondary air supply abnormality detection device for an internal combustion engine, one disclosed in Japanese Patent Publication No. 7-72514 is known. In this technique, a technique for detecting an abnormality of a secondary air introduction mechanism (secondary air introduction device) when a desired amount of secondary air is not supplied into an exhaust passage is disclosed.
[0003]
[Problems to be solved by the invention]
By the way, in the above-described apparatus, as the air-fuel ratio detector, an oxygen sensor (O) whose output voltage is inverted depending on whether the air-fuel ratio of exhaust gas is rich or lean with respect to the stoichiometric air-fuel ratio ₂ Sensor) to detect lean or rich exhaust gas, and determine an abnormality in the secondary air introduction mechanism using an air-fuel ratio correction coefficient determined based on a sensor signal from the air-fuel ratio detector. As described above, by using the oxygen sensor, it is possible to detect whether the exhaust gas is lean or rich, but since the degree of lean / rich is unknown, the detection accuracy of the abnormality of the secondary air introduction mechanism is low. there were.
[0004]
Therefore, the present invention has been made to solve such a problem, and an internal combustion engine capable of improving the accuracy of detecting an abnormality of a secondary air introduction mechanism for introducing secondary air into an exhaust passage in order to activate a catalyst early. It is an object to provide a secondary air supply abnormality detection device for an engine.
[0005]
[Means for Solving the Problems]
According to the secondary air supply abnormality detection device for an internal combustion engine according to the first aspect, the fuel injection amount calculated and supplied by the injection amount calculation means based on various operating parameters of the internal combustion engine is used as the secondary air introduction mechanism by the secondary air introduction mechanism. Immediately after the stop, when the air-fuel ratio is reduced for correction of the air-fuel ratio, the air-fuel ratio becomes lean or more than a predetermined value as a result of detection by the air-fuel ratio detecting means disposed downstream of the secondary air introduction hole in the exhaust passage upstream of the catalyst. , The secondary air remains in the introduced state despite being stopped, and the abnormality determining means determines that the secondary air introduction mechanism is abnormal. As described above, the abnormality detection of the secondary air introduction mechanism is determined using the air-fuel ratio detected by the air-fuel ratio detection means, so that the detection accuracy of the system abnormality is improved.
[0006]
According to the secondary air supply abnormality detection device for an internal combustion engine according to the second aspect, the fuel injection amount calculated and supplied by the injection amount calculation means based on various operating parameters of the internal combustion engine is determined by the secondary air introducing mechanism. When the air-fuel ratio is increased for correction of the air-fuel ratio immediately after the introduction, the air-fuel ratio is richer than a predetermined value as a detection result by the air-fuel ratio detecting means disposed downstream of the secondary air introduction hole in the exhaust passage on the upstream side of the catalyst. Is satisfied, the stopped state is maintained despite the secondary air being introduced, and the abnormality determining means determines that the secondary air introduction mechanism is abnormal. As described above, the abnormality detection of the secondary air introduction mechanism is determined using the air-fuel ratio detected by the air-fuel ratio detection means, so that the detection accuracy of the system abnormality is improved.
[0007]
According to the secondary air supply abnormality detection device for an internal combustion engine according to the third aspect, the fuel injection amount calculated and supplied by the injection amount calculation means based on various operating parameters of the internal combustion engine is used as the secondary air introduction mechanism by the secondary air introduction mechanism. Immediately after the stop, when the amount of fuel is reduced for air-fuel ratio correction, the air-fuel ratio feedback correction coefficient based on the air-fuel ratio detection means disposed downstream of the secondary air introduction hole in the exhaust passage on the upstream side of the catalyst or the annealing coefficient thereof. When the value increases to a predetermined value or more, the secondary air remains in the introduced state despite the stop state, and the abnormality determining means determines that the secondary air introduction mechanism is abnormal. As described above, the abnormality detection of the secondary air introduction mechanism is determined using the air-fuel ratio feedback correction coefficient based on the air-fuel ratio detection means or the smoothed value, whereby the detection accuracy of the system abnormality is improved.
[0008]
According to the secondary air supply abnormality detection device for an internal combustion engine, the fuel injection amount calculated and supplied by the injection amount calculation means based on various operating parameters of the internal combustion engine is determined by the secondary air introduction mechanism. Immediately after the introduction, when the amount is increased for the air-fuel ratio correction, the air-fuel ratio feedback correction coefficient based on the air-fuel ratio detection means disposed downstream of the secondary air introduction hole in the exhaust passage on the upstream side of the catalyst or the annealing coefficient thereof. When the value decreases below the predetermined value, the stopped state is maintained despite the secondary air being introduced, and the abnormality determining means determines that the secondary air introduction mechanism is abnormal. As described above, the abnormality detection of the secondary air introduction mechanism is determined using the air-fuel ratio feedback correction coefficient based on the air-fuel ratio detection means or the smoothed value, whereby the detection accuracy of the system abnormality is improved.
[0009]
According to the secondary air supply abnormality detection device for an internal combustion engine of the fifth aspect, the injection amount is calculated based on the measured intake air amount introduced into the intake passage of the internal combustion engine and detected by the intake air amount detection means and various operating parameters of the internal combustion engine. The average value of the integrated deviation between the supply air-fuel ratio calculated from the fuel injection amount calculated by the means and the measured air-fuel ratio detected by the air-fuel ratio detection means is related to the state of secondary air introduction by the secondary air introduction mechanism. However, when the value becomes equal to or less than the predetermined value, it is determined that the secondary air introduction mechanism is abnormal despite the fact that the secondary air has been introduced, and the abnormality determination means determines that the secondary air introduction mechanism is abnormal. As described above, the abnormality of the secondary air introduction mechanism is determined by using the average value of the integrated deviation between the supply air-fuel ratio based on the fuel injection amount based on the intake air amount measured by the intake air amount detector and the fuel injection amount based on the various operating parameters and the air-fuel ratio measured by the air-fuel ratio detector. Is determined, the detection accuracy of the system abnormality is improved.
[0010]
According to the secondary air supply abnormality detecting device for an internal combustion engine of the sixth aspect, the injection amount calculation is performed based on the measured intake air amount introduced into the intake passage of the internal combustion engine and detected by the intake air amount detecting means and various operating parameters of the internal combustion engine. The average value of the integrated deviation between the supply air-fuel ratio calculated from the fuel injection amount calculated by the means and the measured air-fuel ratio detected by the air-fuel ratio detection means is irrespective of the secondary air introduction mechanism stopping the secondary air. If the secondary air introduction mechanism exceeds the predetermined value, the secondary air introduction mechanism is determined to be abnormal by the abnormality determination means, assuming that the secondary air is in the introduced state despite being stopped. As described above, the abnormality of the secondary air introduction mechanism is determined by using the average value of the integrated deviation between the supply air-fuel ratio based on the fuel injection amount based on the intake air amount measured by the intake air amount detector and the fuel injection amount based on the various operating parameters and the air-fuel ratio measured by the air-fuel ratio detector. Is determined, the detection accuracy of the system abnormality is improved.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0012]
<Example 1>
FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which a secondary air supply abnormality detection device for an internal combustion engine according to a first embodiment of the present invention is applied, and peripheral devices thereof.
[0013]
In FIG. 1, reference numeral 10 denotes an internal combustion engine, and an air flow meter 12 for detecting the amount of intake air introduced through an air cleaner (not shown) is provided upstream of an intake passage 11 of the internal combustion engine 10. Downstream of the air flow meter 12, a throttle valve 13 for setting the amount of intake air to the internal combustion engine 10 is provided. The throttle valve 13 is provided with a throttle opening sensor 14 for detecting a throttle opening. An injector (fuel injection valve) 16 that injects and supplies fuel is disposed near the intake port 15 of each cylinder of the internal combustion engine 10 from the intake passage 11.
[0014]
Then, a mixture of the amount of intake air set by the throttle valve 13 and the fuel injected and supplied by the injector 16 is introduced into the combustion chamber 18 of the internal combustion engine 10 according to the opening and closing timing of the intake valve 17. Further, an ignition plug 19 is provided for each cylinder on the cylinder head side of the internal combustion engine 10, and the mixture in the combustion chamber 18 is ignited by spark discharge of the ignition plug 19. The exhaust gas that has been burned in the combustion chamber 18 is discharged from the combustion chamber 18 to the exhaust passage 22 according to the opening and closing timing of the exhaust valve 21.
[0015]
A well-known three-way catalyst 23 is disposed in the middle of the exhaust passage 22, and an A / F sensor 24 that outputs a linear sensor signal according to the A / F (air-fuel ratio) of the exhaust gas upstream and downstream of the three-way catalyst 23. On the downstream side, there are provided oxygen sensors 25 whose output voltage is inverted depending on whether the A / F of the exhaust gas is rich or lean with respect to the stoichiometric air-fuel ratio. The crankshaft 26 of the internal combustion engine 10 is provided with a crank angle sensor 27 for detecting an engine rotation speed based on a crank angle [° CA (Crank Angle)] which is a rotation angle thereof. Further, the internal combustion engine 10 is provided with a water temperature sensor 28 for detecting the temperature of the cooling water.
[0016]
Next, the configuration of the secondary air introduction mechanism 30 that introduces outside air into the exhaust passage 22 as secondary air will be described. A secondary air introduction passage 31 for introducing secondary air is connected to the exhaust passage 22 on the upstream side of the A / F sensor 24. An air filter 32 is provided on the most upstream side of the secondary air introduction passage 31, and an air pump 33 for supplying secondary air under pressure is provided downstream of the air filter 32.
[0017]
A combination valve 34 is provided downstream of the air pump 33. The combination valve 34 is configured by integrating a pressure-driven open / close valve 35 for opening / closing the secondary air introduction passage 31 and a check valve 36 on the downstream side thereof. The opening / closing valve 35 of the combination valve 34 is connected to the intake passage 11 via an intake pressure introducing passage 37, and the drive pressure of the opening / closing valve 35 is controlled by an electromagnetically driven switching valve 38 provided in the middle of the intake pressure introducing passage 37. Is switched between atmospheric pressure and intake pressure.
[0018]
That is, when the secondary air is introduced, the switching valve 38 is switched to “ON (on)”, which is the intake pressure introduction position, and the intake pressure is introduced into the opening / closing valve 35, so that the opening / closing valve 35 is opened. . As a result, the secondary air discharged from the air pump 33 passes through the on-off valve 35 and flows to the check valve 36 side. The check valve 36 is opened by the pressure, and the secondary air is introduced into the exhaust passage 22. Is done.
[0019]
On the other hand, when the secondary air is stopped, the switching valve 38 is switched to “OFF (off)”, which is the atmospheric pressure introduction position, and the atmospheric pressure is introduced into the opening / closing valve 35, thereby closing the opening / closing valve 35. . As a result, the secondary air to the exhaust passage 22 is stopped, and the pressure of the secondary air does not act on the check valve 36, so that the pressure on the exhaust passage 22 side is increased. The valve is closed to prevent the exhaust gas in the exhaust passage 22 from flowing back to the air pump 33 side.
[0020]
Numeral 40 denotes an ECU (Electronic Control Unit), which stores a CPU 41 as a central processing unit for executing various known arithmetic processing, a ROM 42 storing a control program, a control map, and the like, and various data. It is configured as a logical operation circuit including a RAM 43, a B / U (backup) RAM 44, an input / output circuit 45, and a bus line 46 connecting them. The various sensor signals described above are input to the ECU 40, and control signals are output from the ECU 40 to the injector 16, the spark plug 19, the air pump 33 of the secondary air introduction mechanism 30, the switching valve 38, and the like.
[0021]
Next, a processing procedure of secondary air supply abnormality detection by the CPU 41 in the ECU 40 used in the secondary air supply abnormality detection device of the internal combustion engine according to the first example of the embodiment of the present invention is shown in FIG. This will be described with reference to FIG. 3 based on a flowchart. Here, FIG. 3 is a time chart showing the transition state of the secondary air “ON” / “OFF”, the secondary air fuel correction amount, and the A / F sensor value corresponding to the processing of FIG. Note that this secondary air supply abnormality detection routine is repeatedly executed by the CPU 41 at predetermined time intervals.
[0022]
In FIG. 2, first, in step S101, it is determined whether the secondary air is “ON”. If the determination condition of step S101 is not satisfied, that is, if the secondary air is OFF and the secondary air introduction mechanism 30 is in an inactive state (time t00 to time t01 shown in FIG. 3), the process proceeds to step S102. It is determined whether the correction amount obtained by subtracting the predetermined amount α from the previous correction amount (previous secondary air fuel correction amount) is “0 (zero)” or more. When the determination condition of step S102 is satisfied, that is, when the correction amount obtained by subtracting the predetermined amount α from the previous correction amount is larger than “0”, the process proceeds to step S103, and the correction amount obtained by subtracting the predetermined amount α from the previous correction amount becomes the current time. Is the secondary air fuel correction amount.
[0023]
Next, the process proceeds to step S104, where the A / F sensor value from the A / F sensor 24 is read. Next, the process proceeds to step S105, and it is determined whether the A / F sensor value read in step S104 is equal to or greater than a predetermined determination value 1. When the determination condition of step S105 is satisfied, that is, when the A / F sensor value of the A / F sensor 24 is larger than the determination value 1, the process proceeds to step S106, and it is determined that the secondary air supply is abnormal, and the present routine ends. .
[0024]
That is, in FIG. 3, immediately after the secondary air changes from “ON” to “OFF”, the secondary air fuel correction amount is reduced to “0” from the predetermined amount up to that point. At this time, if the secondary air introduction mechanism 30 is normal, the A / F sensor value is once stoichiometric (theoretical) to such an extent that it slightly swings to the rich side as shown by a thin solid line as normal after time t00 in FIG. Return to (air-fuel ratio). However, if the secondary air introduction mechanism 30 is abnormal, the secondary air remains in the “ON” introduction state indicated by the thick two-dot chain line after time t00 in FIG. 3, and the A / F sensor value is After the time t00 of No. 3, as indicated by a thick two-dot chain line as an abnormal time, the value exceeds the determination value 1 and largely swings to the lean side. Thereafter, if the A / F (air-fuel ratio) feedback control is executed, the A / F sensor value returns to the stoichiometric state as in the case where the secondary air introduction mechanism 30 is normal. If the secondary air introduction mechanism 30 is abnormal and the A / F feedback control is not being executed, the A / F sensor value remains in a lean state as shown by a thick broken line after time t00 in FIG. It becomes.
[0025]
On the other hand, when the determination condition of step S102 is not satisfied, that is, when the correction amount obtained by subtracting the predetermined amount α from the previous correction amount is smaller than “0”, the process proceeds to step S107, and after the correction amount is set to “0”. Then, this routine ends. If the determination condition in step S105 is not satisfied, that is, if the A / F sensor value of the A / F sensor 24 is smaller than the determination value 1, it is determined that the secondary air supply is normal, and this routine ends.
[0026]
On the other hand, when the determination condition of step S101 is satisfied, that is, when the secondary air is ON and the secondary air introduction mechanism 30 is operating (before time t00 and after time t01 shown in FIG. 3), the process proceeds to step S108. Then, it is determined whether the correction amount obtained by adding the predetermined amount β to the previous correction amount (previous secondary air fuel correction amount) is equal to or smaller than a predetermined value. When the determination condition of step S108 is satisfied, that is, when the correction amount obtained by adding the predetermined amount β to the previous correction amount is smaller than the predetermined value, the process proceeds to step S109, and the correction amount obtained by adding the predetermined amount β to the previous correction amount becomes the current correction amount. This is the secondary air fuel correction amount.
[0027]
Next, the process proceeds to step S110, where the A / F sensor value from the A / F sensor 24 is read. Next, the process proceeds to step S111, and it is determined whether the A / F sensor value read in step S110 is equal to or less than a predetermined determination value 2. When the determination condition of step S111 is satisfied, that is, when the A / F sensor value by the A / F sensor 24 is smaller than the determination value 2 or less, the process proceeds to step S106, and it is determined that the secondary air supply is abnormal, and the present routine ends. .
[0028]
That is, in FIG. 3, immediately after the secondary air is changed from “OFF” to “ON”, the secondary air fuel correction amount is increased from “0” to a predetermined amount. At this time, if the secondary air introduction mechanism 30 is normal, the A / F sensor value is stoichiometric (theoretically) at a degree that once swings slightly to the lean side as shown by a thin solid line as normal after time t01 in FIG. Return to air-fuel ratio). However, if the secondary air introduction mechanism 30 is abnormal, the secondary air remains in the “OFF” stop state as shown by the thick two-dot chain line after time t01 in FIG. 3, and the A / F sensor value As shown by a thick two-dot chain line as an abnormal time after time t01 in FIG. Thereafter, if the A / F feedback control is executed, the A / F sensor value returns to the stoichiometric state as in the case where the secondary air introduction mechanism 30 is normal. If the secondary air introduction mechanism 30 is abnormal and the A / F feedback control is not executed, the A / F sensor value remains in a rich state as shown by a thick broken line after time t01 in FIG. Become.
[0029]
On the other hand, when the determination condition in step S108 is not satisfied, that is, when the correction amount obtained by adding the predetermined amount β to the previous correction amount exceeds the predetermined value and is larger, the process proceeds to step S112, and after the correction amount is set to the predetermined value, End the routine. When the determination condition of step S111 is not satisfied, that is, when the A / F sensor value of the A / F sensor 24 exceeds the determination value 2 and is large, it is determined that the secondary air supply is normal, and this routine ends.
[0030]
As described above, the secondary air supply abnormality detection device for the internal combustion engine according to the present embodiment is provided in the exhaust passage 22 of the internal combustion engine 10 and purifies the exhaust gas, and the upstream side of the three-way catalyst 23. And a secondary air introduction mechanism 30 for introducing secondary air into the exhaust passage 22 of the first and second catalysts, and a downstream of the secondary air introduction hole 31a of the secondary air introduction passage 31 in the exhaust passage 22 on the upstream side of the three-way catalyst 23. An A / F sensor 24 as an air-fuel ratio detecting means for detecting an A / F (air-fuel ratio) in the exhaust gas, and an ECU 40 for calculating a fuel injection amount to be supplied to the internal combustion engine 10 based on various operation parameters. When the fuel injection amount is reduced for the air-fuel ratio correction immediately after the secondary air is stopped by the secondary air introduction mechanism 30, the determination is made as the detection result by the A / F sensor 24. Lean more than value 1 When the are those comprising an abnormality judging means to be achieved by CPU41 in ECU40 determines secondary air introducing mechanism 30 to be abnormal.
[0031]
That is, when the fuel injection amount calculated and supplied based on various operating parameters of the internal combustion engine 10 is reduced for the air-fuel ratio correction immediately after the secondary air is stopped by the secondary air introduction mechanism 30, the detection by the A / F sensor 24 is performed. As a result, when the lean value becomes equal to or more than the determination value 1, it is determined that the secondary air introduction mechanism 30 is abnormal, even though the secondary air is stopped, despite the stop state. As described above, by determining the abnormality of the secondary air introduction mechanism 30 using the A / F sensor value, the detection accuracy of the abnormality can be improved.
[0032]
Further, the secondary air supply abnormality detection device for an internal combustion engine according to the present embodiment is installed in the exhaust passage 22 of the internal combustion engine 10 and purifies exhaust gas. A secondary air introduction mechanism 30 for introducing secondary air into the passage 22 and a secondary air introduction passage 31 disposed downstream of the secondary air introduction hole 31 a in the exhaust passage 22 upstream of the three-way catalyst 23. An A / F sensor 24 as an air-fuel ratio detecting means for detecting an A / F (air-fuel ratio) in the exhaust gas, and a CPU 41 in the ECU 40 for calculating a fuel injection amount to be supplied to the internal combustion engine 10 based on various operating parameters. When the fuel injection amount is increased for the air-fuel ratio correction immediately after the secondary air is introduced by the secondary air introduction mechanism 30, the determination value 2 is obtained as a detection result by the A / F sensor 24. When it became rich To are those comprising an abnormality judging means to be achieved by CPU41 in ECU40 determines secondary air introducing mechanism 30 to be abnormal.
[0033]
That is, when the fuel injection amount calculated and supplied based on various operating parameters of the internal combustion engine 10 is increased for the air-fuel ratio correction immediately after the secondary air introduction by the secondary air introduction mechanism 30, the detection by the A / F sensor 24 is performed. As a result, when the determination value becomes 2 or more rich, it is determined that the secondary air introduction mechanism 30 is abnormal, even though the secondary air has been introduced, but remains stopped. As described above, by determining the abnormality of the secondary air introduction mechanism 30 using the A / F sensor value, the detection accuracy of the abnormality can be improved.
[0034]
<Example 2>
FIG. 4 is a flowchart showing a processing procedure for detecting a secondary air supply abnormality in the CPU 41 in the ECU 40 used in the secondary air supply abnormality detection apparatus for an internal combustion engine according to the second example of the embodiment of the present invention. FIG. 5 shows the transition states of the "ON" / "OFF" of the secondary air, the smoothed value of the A / F (air-fuel ratio) feedback fuel correction coefficient, and the A / F sensor value corresponding to the processing of FIG. It is a chart. Note that this secondary air supply abnormality detection routine is repeatedly executed by the CPU 41 at predetermined time intervals. Further, the configuration of the secondary air supply abnormality detecting device for an internal combustion engine according to the present embodiment is the same as the schematic diagram of FIG.
[0035]
In FIG. 4, first, in step S201, it is determined whether the secondary air is “ON”. If the determination condition of step S201 is not satisfied, that is, if the secondary air is OFF and the secondary air introduction mechanism 30 is in an inactive state (time t10 to time t11 shown in FIG. 5), the process proceeds to step S202. It is determined whether the correction amount obtained by subtracting the predetermined amount γ from the previous correction amount (previous secondary air fuel correction amount) is “0” or more. When the determination condition of step S202 is satisfied, that is, when the correction amount obtained by subtracting the predetermined amount γ from the previous correction amount is greater than or equal to “0”, the process proceeds to step S203, and the correction amount obtained by subtracting the predetermined amount γ from the previous correction amount becomes Is the secondary air fuel correction amount.
[0036]
Next, the process proceeds to step S204, where the smoothed value obtained by smoothing the A / F feedback correction coefficient based on the A / F sensor value from the A / F sensor 24 is read. Next, the process proceeds to step S205, and it is determined whether the average value of the A / F feedback correction coefficient read in step S204 is equal to or greater than a predetermined determination value 3. If the determination condition of step S205 is satisfied, that is, if the smoothed value of the A / F feedback correction coefficient is larger than the determination value 3, the process proceeds to step S206, and it is determined that the secondary air supply is abnormal, and this routine ends.
[0037]
That is, in FIG. 5, immediately after the secondary air is changed from “ON” to “OFF”, the smoothed value of the A / F feedback correction coefficient is equal to that of FIG. As shown by a thin solid line in the normal state after the time t10, only a slight change is made so as to decrease the smoothed value of the A / F feedback correction coefficient. However, if the secondary air introduction mechanism 30 is abnormal, the smoothed value of the A / F feedback correction coefficient exceeds the determination value 3 so as to be increased after the time t10 in FIG. As a result, the A / F sensor value largely fluctuates to the lean side as indicated by a thick two-dot chain line as an abnormal state after time t10 in FIG. Thereafter, if the A / F feedback control is executed, the A / F sensor value returns to the stoichiometric state as in the case where the secondary air introduction mechanism 30 is normal. If the secondary air introduction mechanism 30 is abnormal and the A / F feedback control is not executed, the A / F sensor value remains in a lean state as shown by a thick broken line after time t10 in FIG. It becomes.
[0038]
On the other hand, when the determination condition of step S202 is not satisfied, that is, when the correction amount obtained by subtracting the predetermined amount γ from the previous correction amount is smaller than “0”, the process proceeds to step S207, and after the correction amount is set to “0”. Then, this routine ends. When the determination condition of step S205 is not satisfied, that is, when the average value of the A / F feedback correction coefficient is smaller than the determination value 3, it is determined that the secondary air supply is normal, and this routine ends.
[0039]
On the other hand, when the determination condition of step S201 is satisfied, that is, when the secondary air is ON and the secondary air introduction mechanism 30 is in the operating state (before time t10 and after time t11 shown in FIG. 5), the process proceeds to step S208. Then, it is determined whether the correction amount obtained by adding the predetermined amount δ to the previous correction amount is equal to or smaller than a predetermined value. When the determination condition of step S208 is satisfied, that is, when the correction amount obtained by adding the predetermined amount δ to the previous correction amount is smaller than the predetermined value, the process proceeds to step S209, and the correction amount obtained by adding the predetermined amount δ to the previous correction amount is This is the secondary air fuel correction amount.
[0040]
Next, the process proceeds to step S210, where the smoothed value obtained by smoothing the A / F feedback correction coefficient based on the A / F sensor value from the A / F sensor 24 is read. Next, the process proceeds to step S211, and it is determined whether the average value of the A / F feedback correction coefficient read in step S210 is equal to or less than a predetermined determination value 4. When the determination condition of step S211 is satisfied, that is, when the average value of the A / F feedback correction coefficient is smaller than the determination value 4, the process proceeds to step S206, and it is determined that the secondary air supply is abnormal, and the present routine ends.
[0041]
That is, as shown in FIG. 5, immediately after the secondary air is changed from “OFF” to “ON”, the smoothed value of the A / F feedback correction coefficient is determined if the secondary air introduction mechanism 30 is normal. After the time t11 in FIG. 5, as shown by a thin solid line as a normal state, it is only slightly increased temporarily and changes. However, if the secondary air introduction mechanism 30 is abnormal, the smoothed value of the A / F feedback correction coefficient is decreased after the time t11 in FIG. As a result, the A / F sensor value greatly fluctuates to the rich side as indicated by a thick two-dot chain line as an abnormal state after time t11 in FIG. Thereafter, if the A / F feedback control is executed, the A / F sensor value returns to the stoichiometric state as in the case where the secondary air introduction mechanism 30 is normal. If the secondary air introduction mechanism 30 is abnormal and the A / F feedback control is not executed, the A / F sensor value remains in a rich state as shown by a thick broken line after time t11 in FIG. It becomes.
[0042]
On the other hand, if the determination condition in step S208 is not satisfied, that is, if the correction amount obtained by adding the predetermined amount δ to the previous correction amount exceeds the predetermined value and is larger, the process proceeds to step S212, and after the correction amount is set to the predetermined value, End the routine. When the determination condition of step S211 is not satisfied, that is, when the average value of the A / F feedback correction coefficient exceeds the determination value 4 and is large, it is determined that the secondary air supply is normal, and this routine ends.
[0043]
As described above, the secondary air supply abnormality detection device for the internal combustion engine according to the present embodiment is provided in the exhaust passage 22 of the internal combustion engine 10 and purifies the exhaust gas, and the upstream side of the three-way catalyst 23. And a secondary air introduction mechanism 30 for introducing secondary air into the exhaust passage 22 of the first and second catalysts, and a downstream of the secondary air introduction hole 31a of the secondary air introduction passage 31 in the exhaust passage 22 on the upstream side of the three-way catalyst 23 An A / F sensor 24 as an air-fuel ratio detecting means for detecting an A / F (air-fuel ratio) in the exhaust gas, and an ECU 40 for calculating a fuel injection amount to be supplied to the internal combustion engine 10 based on various operation parameters. When the fuel injection amount is reduced for the air-fuel ratio correction immediately after the secondary air is stopped by the secondary air introduction mechanism 30, the A / F based on the A / F sensor 24 is used. Feedback correction coefficient When the value is increased to the judgment value 3 or more are those comprising an abnormality judging means to be achieved by CPU41 in ECU40 determines secondary air introducing mechanism 30 to be abnormal.
[0044]
That is, when the fuel injection amount calculated and supplied based on various operating parameters of the internal combustion engine 10 is reduced for air-fuel ratio correction immediately after the secondary air is stopped by the secondary air introduction mechanism 30, the A / F sensor 24 is used. When the smoothed value of the A / F feedback correction coefficient increases to the determination value 3 or more, the secondary air remains in the introduced state despite the stop state of the secondary air, and the secondary air introduction mechanism 30 is abnormal. Can be determined. As described above, the abnormality detection of the secondary air introduction mechanism 30 is determined using the smoothed value of the A / F feedback correction coefficient based on the A / F sensor 24, so that the abnormality detection accuracy can be improved.
[0045]
Further, the secondary air supply abnormality detection device for an internal combustion engine according to the present embodiment is installed in the exhaust passage 22 of the internal combustion engine 10 and purifies exhaust gas. A secondary air introduction mechanism 30 for introducing secondary air into the passage 22 and a secondary air introduction passage 31 disposed downstream of the secondary air introduction hole 31 a in the exhaust passage 22 upstream of the three-way catalyst 23. An A / F sensor 24 as an air-fuel ratio detecting means for detecting an A / F (air-fuel ratio) in the exhaust gas, and a CPU 41 in the ECU 40 for calculating a fuel injection amount to be supplied to the internal combustion engine 10 based on various operating parameters. A / F feedback correction based on the A / F sensor 24 when the fuel injection amount is increased for air-fuel ratio correction immediately after the introduction of the secondary air by the secondary air introduction mechanism 30 The average value of the coefficient is When reduced to value 4 or less are those comprising an abnormality judging means to be achieved by CPU41 in ECU40 determines secondary air introducing mechanism 30 to be abnormal.
[0046]
That is, when the fuel injection amount calculated and supplied based on various operating parameters of the internal combustion engine 10 is increased for the air-fuel ratio correction immediately after the secondary air introduction by the secondary air introduction mechanism 30, the A / F sensor 24 is used. When the average value of the A / F feedback correction coefficient decreases to the determination value 4 or less, it is determined that the secondary air introduction mechanism 30 is abnormal even though the secondary air has been introduced. Can be determined. As described above, the abnormality detection of the secondary air introduction mechanism 30 is determined using the smoothed value of the A / F feedback correction coefficient based on the A / F sensor 24, so that the abnormality detection accuracy can be improved.
[0047]
<Example 3>
FIG. 6 is a flowchart showing a processing procedure for detecting a secondary air supply abnormality in the CPU 41 in the ECU 40 used in the secondary air supply abnormality detection apparatus for an internal combustion engine according to the third example of the embodiment of the present invention. . Note that this secondary air supply abnormality detection routine is repeatedly executed by the CPU 41 at predetermined time intervals. Further, the configuration of the secondary air supply abnormality detecting device for an internal combustion engine according to the present embodiment is the same as the schematic diagram of FIG.
[0048]
In FIG. 6, first, in step S301, it is determined whether the internal combustion engine 10 is in a steady operation. When the determination condition of step S301 is satisfied, that is, when the internal combustion engine 10 is in a steady operation and is not in rapid acceleration / deceleration, the process proceeds to step S302, and it is determined whether the state of the secondary air introduction mechanism 30 has changed. If the determination condition of step S302 is not satisfied, that is, if there is no change in the state of the secondary air introduction mechanism 30, the process proceeds to step S303, and the intake air amount measured by the air flow meter 12 is read. Next, the process proceeds to step S304, where the fuel injection amount is calculated from the fuel injection time.
[0049]
Next, the process proceeds to step S305, where the measured intake air amount read in step S303 is divided by the fuel injection amount calculated in step S304 to calculate the supply A / F (air-fuel ratio). Next, the process proceeds to step S306, where the measurement A / F by the A / F sensor 24 is read. Next, the process proceeds to step S307, and it is determined whether or not the number counter N is equal to or greater than a predetermined number ε. When the determination condition of step S307 is satisfied, that is, when the number counter N is greater than or equal to the predetermined number ε, the process proceeds to step S308, and the measurement A / F read in step S306 is subtracted from the supply A / F calculated in step S305. The total value of the absolute values of the calculated values is divided by the number counter N to calculate an integrated deviation average value.
[0050]
Next, the process proceeds to step S309, where it is determined whether the secondary air is “ON”. When the determination condition of step S309 is satisfied, that is, when the secondary air is ON and the secondary air introduction mechanism 30 is in the operating state, the process proceeds to step S310, and the integrated deviation average value calculated in step S308 is set in advance. It is determined whether the value is equal to or less than the determination value 5. When the determination condition of step S310 is satisfied, that is, when the integrated deviation average value is smaller than the determination value 5, the process proceeds to step S311 and the secondary air introduction mechanism 30 is not turned “ON”, that is, the secondary air is not supplied. This routine is determined to be abnormal, and the routine ends. On the other hand, when the determination condition of step S310 is not satisfied, that is, when the integrated deviation average value exceeds the determination value 5 and is large, it is determined that the secondary air supply is normal, and this routine is ended.
[0051]
On the other hand, when the determination condition of step S309 is not satisfied, that is, when the secondary air is OFF and the secondary air introduction mechanism 30 is in an inoperative state, the process proceeds to step S312, and the integrated deviation average value calculated in step S308 Is greater than or equal to a predetermined determination value 6. When the determination condition of step S312 is satisfied, that is, when the integrated deviation average value is larger than the determination value 6, the process proceeds to step S313, and the secondary air introduction mechanism 30 does not become “OFF”, that is, the secondary air supply is not performed. Assuming that there is no secondary air supply abnormality without ぱ, this routine ends.
[0052]
On the other hand, when the determination condition of step S301 is not satisfied, that is, when the internal combustion engine 10 is in transient acceleration and deceleration, or when the determination condition of step S302 is satisfied, that is, there is a state change in the secondary air introduction mechanism 30. Or when the determination condition of step S307 is not satisfied, that is, when the number counter N is smaller than a predetermined number ε, or when the determination condition of step S312 is not satisfied, that is, when the integrated deviation average value is less than the determination value 6, If it is smaller, it is determined that the secondary air supply is normal, and this routine ends.
[0053]
As described above, the secondary air supply abnormality detection device for an internal combustion engine according to the present embodiment includes an air flow meter 12 as intake air amount detection means for detecting an intake air amount introduced into an intake passage 11 of an internal combustion engine 10, and an internal combustion engine. A three-way catalyst 23 installed in the middle of the exhaust passage 22 for purifying exhaust gas; a secondary air introduction mechanism 30 for introducing secondary air into the exhaust passage 22 upstream of the three-way catalyst 23; Air-fuel ratio detecting means disposed in the exhaust passage 22 on the upstream side of the catalyst 23 and downstream of the secondary air introduction hole 31a of the secondary air introduction passage 31 to detect A / F (air-fuel ratio) in exhaust gas An A / F sensor 24, an injection amount calculating means achieved by a CPU 41 in an ECU 40 for calculating a fuel injection amount to be supplied to the internal combustion engine 10 based on various operating parameters, and a secondary Air introduction mechanism 30 When there is no state change, the integrated value of the deviation between the supply A / F calculated from the intake air amount and the fuel injection amount supplied to the internal combustion engine 10 and the measurement A / F detected by the A / F sensor 24 is calculated. When the integrated deviation average value divided by the number of times of integration is equal to or less than the determination value 5 regardless of the state of secondary air introduction by the secondary air introduction mechanism 30, the ECU 40 that determines that the secondary air introduction mechanism 30 is abnormal is provided. Abnormality determination means achieved by the CPU 41 described above.
[0054]
That is, the supply A / F and A are calculated from the measured intake air amount introduced into the intake passage 11 of the internal combustion engine 10 and detected by the air flow meter 12 and the fuel injection amount calculated based on various operating parameters of the internal combustion engine 10. When the integrated deviation average value based on the measurement A / F detected by the / F sensor 24 is equal to or less than the determination value 5 regardless of the state of the secondary air introduction by the secondary air introduction mechanism 30, the secondary air is introduced. It can be determined that the secondary air introduction mechanism 30 is abnormal despite the state being stopped, and it can be determined that the secondary air introduction mechanism 30 is abnormal. As described above, the secondary air introduction mechanism is provided by using the average value of the integrated deviation between the supply A / F measured by the air flow meter 12 and the supply A / F based on the fuel injection amount based on various operation parameters and the A / F measured by the A / F sensor 24. By judging 30 abnormalities, the accuracy of abnormality detection can be improved.
[0055]
The secondary air supply abnormality detection device for an internal combustion engine according to the present embodiment includes an air flow meter 12 as an intake air amount detection unit that detects an intake air amount introduced into an intake passage 11 of the internal combustion engine 10, A three-way catalyst 23 installed in the exhaust passage 22 for purifying exhaust gas; a secondary air introduction mechanism 30 for introducing secondary air into the exhaust passage 22 on the upstream side of the three-way catalyst 23; Is disposed downstream of the secondary air introduction hole 31a of the secondary air introduction passage 31 in the exhaust passage 22 on the upstream side of the exhaust gas, and serves as air-fuel ratio detection means for detecting A / F (air-fuel ratio) in the exhaust gas. An A / F sensor 24, an injection amount calculation means achieved by a CPU 41 in an ECU 40 for calculating a fuel injection amount to be supplied to the internal combustion engine 10 based on various operation parameters, and secondary air introduction when the internal combustion engine 10 is in a steady state. State in mechanism 30 When there is no conversion, the integrated value of the deviation between the supply A / F calculated from the intake air amount and the fuel injection amount supplied to the internal combustion engine 10 and the measurement A / F detected by the A / F sensor 24 is integrated. When the integrated deviation average value divided by the number of times is equal to or greater than the determination value 6 in spite of the secondary air introduction mechanism 30 stopping the secondary air, the ECU 40 determines that the secondary air introduction mechanism 30 is abnormal. An abnormality determining means achieved by the CPU 41 is provided.
[0056]
That is, the supply A / F and A are calculated from the measured intake air amount introduced into the intake passage 11 of the internal combustion engine 10 and detected by the air flow meter 12 and the fuel injection amount calculated based on various operating parameters of the internal combustion engine 10. When the integrated deviation average value based on the measurement A / F detected by the / F sensor 24 is equal to or larger than the determination value 6 despite the secondary air introduction mechanism 30 stopping the secondary air, the secondary air is stopped. It is determined that the secondary air introduction mechanism 30 is in the introduced state despite the state, and it can be determined that the secondary air introduction mechanism 30 is abnormal. As described above, the secondary air introduction mechanism is provided by using the average value of the integrated deviation between the supply A / F measured by the air flow meter 12 and the supply A / F based on the fuel injection amount based on various operation parameters and the A / F measured by the A / F sensor 24. By judging 30 abnormalities, the accuracy of abnormality detection can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which a secondary air supply abnormality detection device for an internal combustion engine according to first to third embodiments of the present invention is applied, and peripheral devices thereof; It is.
FIG. 2 shows a processing procedure for detecting a secondary air supply abnormality in a CPU in an ECU used in a secondary air supply abnormality detection apparatus for an internal combustion engine according to a first embodiment of the present invention. It is a flowchart shown.
FIG. 3 is a time chart showing transition states of various sensor signals, various control amounts, and the like corresponding to the processing of FIG. 2;
FIG. 4 shows a processing procedure of secondary air supply abnormality detection by a CPU in an ECU used in a secondary air supply abnormality detection apparatus for an internal combustion engine according to a second embodiment of the present invention. It is a flowchart shown.
FIG. 5 is a time chart showing transition states of various sensor signals, various control amounts, and the like corresponding to the processing of FIG. 4;
FIG. 6 shows a processing procedure of secondary air supply abnormality detection by a CPU in an ECU used in a secondary air supply abnormality detection apparatus for an internal combustion engine according to a third embodiment of the present invention. It is a flowchart shown.
[Explanation of symbols]
10 Internal combustion engine
11 Intake passage
12 Air flow meter
22 Exhaust passage
23 Three-way catalyst
24 A / F (air-fuel ratio) sensor
27 Crank angle sensor
30 Secondary air introduction mechanism
31 Secondary air introduction passage
31a Secondary air inlet

Claims (6)

A catalyst installed in the exhaust passage of the internal combustion engine for purifying exhaust gas,
A secondary air introduction mechanism for introducing secondary air into the exhaust passage upstream of the catalyst;
Air-fuel ratio detection means disposed in the exhaust passage on the upstream side of the catalyst and downstream of the inlet port for secondary air to detect an air-fuel ratio in exhaust gas;
Injection amount calculation means for calculating a fuel injection amount to be supplied to the internal combustion engine based on various operation parameters,
Immediately after stopping the secondary air by the secondary air introduction mechanism, when the fuel injection amount is reduced for air-fuel ratio correction, when the air-fuel ratio detection means becomes lean by a predetermined value or more, the secondary air introduction is performed. A secondary air supply abnormality detection device for an internal combustion engine, comprising: abnormality determination means for determining that the mechanism is abnormal. A catalyst installed in the exhaust passage of the internal combustion engine for purifying exhaust gas,
A secondary air introduction mechanism for introducing secondary air into the exhaust passage upstream of the catalyst;
Air-fuel ratio detection means disposed in the exhaust passage on the upstream side of the catalyst and downstream of the inlet port for secondary air to detect an air-fuel ratio in exhaust gas;
Injection amount calculation means for calculating a fuel injection amount to be supplied to the internal combustion engine based on various operation parameters,
Immediately after the introduction of the secondary air by the secondary air introduction mechanism, when the fuel injection amount is increased for air-fuel ratio correction, and when the air-fuel ratio detection means becomes richer than a predetermined value, the secondary air introduction is performed. A secondary air supply abnormality detection device for an internal combustion engine, comprising: abnormality determination means for determining that the mechanism is abnormal. A catalyst installed in the exhaust passage of the internal combustion engine for purifying exhaust gas,
A secondary air introduction mechanism for introducing secondary air into the exhaust passage upstream of the catalyst;
Air-fuel ratio detection means disposed in the exhaust passage on the upstream side of the catalyst and downstream of the inlet port for secondary air to detect an air-fuel ratio in exhaust gas;
Injection amount calculation means for calculating a fuel injection amount to be supplied to the internal combustion engine based on various operation parameters,
When the fuel injection amount is reduced for air-fuel ratio correction immediately after the secondary air is stopped by the secondary air introduction mechanism, the air-fuel ratio feedback correction coefficient based on the air-fuel ratio detection means or its smoothing value increases to a predetermined value or more. Abnormality detecting means for judging the secondary air introduction mechanism to be abnormal when the secondary air supply mechanism is abnormal. A catalyst installed in the exhaust passage of the internal combustion engine for purifying exhaust gas,
A secondary air introduction mechanism for introducing secondary air into the exhaust passage upstream of the catalyst;
Air-fuel ratio detection means disposed in the exhaust passage on the upstream side of the catalyst and downstream of the inlet port for secondary air to detect an air-fuel ratio in exhaust gas;
Injection amount calculation means for calculating a fuel injection amount to be supplied to the internal combustion engine based on various operation parameters,
When the fuel injection amount is increased for air-fuel ratio correction immediately after the introduction of the secondary air by the secondary air introduction mechanism, the air-fuel ratio feedback correction coefficient based on the air-fuel ratio detecting means or the smoothing value decreases to a predetermined value or less. Abnormality detecting means for judging the secondary air introduction mechanism to be abnormal when the secondary air supply mechanism is abnormal. Intake air amount detecting means for detecting an intake air amount introduced into an intake passage of the internal combustion engine,
A catalyst installed in the exhaust passage of the internal combustion engine to purify exhaust gas;
A secondary air introduction mechanism for introducing secondary air into the exhaust passage upstream of the catalyst;
Air-fuel ratio detection means disposed in the exhaust passage on the upstream side of the catalyst and downstream of the inlet port for secondary air to detect an air-fuel ratio in exhaust gas;
Injection amount calculation means for calculating a fuel injection amount to be supplied to the internal combustion engine based on various operation parameters,
When the state of the secondary air introduction mechanism does not change in the steady state of the internal combustion engine, the air-fuel ratio calculated from the intake air amount and the fuel injection amount supplied to the internal combustion engine and the air-fuel ratio detecting means are detected. When the integrated deviation average value obtained by dividing the integrated value of the deviation from the air-fuel ratio by the number of times of integration is equal to or smaller than a predetermined value regardless of the state of introduction of the secondary air by the secondary air introduction mechanism, A secondary air supply abnormality detection device for an internal combustion engine, comprising: abnormality determination means for determining that the introduction mechanism is abnormal. Intake air amount detecting means for detecting an intake air amount introduced into an intake passage of the internal combustion engine,
A catalyst installed in the exhaust passage of the internal combustion engine to purify exhaust gas;
A secondary air introduction mechanism for introducing secondary air into the exhaust passage upstream of the catalyst;
Air-fuel ratio detection means disposed in the exhaust passage on the upstream side of the catalyst and downstream of the inlet port for secondary air to detect an air-fuel ratio in exhaust gas;
Injection amount calculation means for calculating a fuel injection amount to be supplied to the internal combustion engine based on various operation parameters,
When there is no change in the state of the secondary air introduction mechanism in the steady state of the internal combustion engine, the supply air-fuel ratio calculated from the intake air amount and the fuel injection amount supplied to the internal combustion engine is detected by the air-fuel ratio detection means. When the integrated deviation average value obtained by dividing the integrated value of the deviation from the measured air-fuel ratio by the number of times of integration becomes equal to or larger than a predetermined value despite the secondary air introduction mechanism stopping the secondary air. A secondary air supply abnormality detection device for an internal combustion engine, comprising: abnormality determination means for determining that the secondary air introduction mechanism is abnormal.

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