JP2007332932A - Abnormality diagnosis device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent erroneous determination of existence of abnormality when transient abnormality occurs. <P>SOLUTION: There occurs abnormality which interferes with adjustment of a catalyst bed temperature average value Tave to a target bed temperature Tt during temperature rising control for filter regeneration. There exist some cases where such abnormality is caused permanently and the other where the abnormality is caused transiently. If the abnormality determination is made immediately after a learning value K updated to be a value corresponding to a deviation between the catalyst bed temperature average value Tave and target bed temperature Tt becomes a value out of an appropriate range even once, the determination results in an error even when the device is recovered from the abnormality thereafter and the learning value K falls within the appropriate range again. In order to prevent such occurrence, the count-up performed when the learning value K at update is a value out of the appropriate range is utilized to determine the occurrence of the abnormality. The determination of the abnormality occurrence is made if a counter value of a counter C for resetting the learning value K to an initial value "0" when the learning value K is within the appropriate range reaches the determination value of "2" or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an abnormality diagnosis device for an internal combustion engine.

  Conventionally, as an exhaust gas purification device applied to an internal combustion engine such as a vehicle-mounted diesel engine, a PM filter that collects particulates (PM) mainly containing soot and exhaust gas purification related to nitrogen oxide (NOx) are performed. 2. Description of the Related Art An exhaust system provided with a catalytic converter that supports an NOx storage reduction catalyst is known. In such an exhaust purification device, temperature increase control is performed to raise the temperature of the catalyst to a target bed temperature through the supply of unburned fuel components to the catalyst for the purpose of recovering the exhaust purification capability.

  For example, in the PM filter and the catalytic converter, clogging due to accumulation of fine particles occurs, so that the fine particles are burned (oxidized) to perform filter regeneration to eliminate the clogging. Control is implemented. In this temperature rise control, components such as hydrocarbons (HC) and carbon monoxide (CO) are oxidized in the exhaust or on the catalyst by supplying unburned fuel components to the catalyst, and accompanying the oxidation reaction. The catalyst bed temperature is raised to the target bed temperature by heat generation. As the catalyst bed temperature rises in this way, the particulates deposited when the PM filter and the catalytic converter are placed in a high temperature environment are removed, and the particulate collection ability of the PM filter is recovered.

  By the way, when the temperature increase control is executed, even if an attempt is made to raise the catalyst bed temperature to the target bed temperature by supplying the unburned fuel component to the catalyst, the catalyst bed temperature may not reach the target bed temperature. For example, when the fuel supply system for supplying the unburned fuel component to the catalyst is clogged, the supply amount of the unburned fuel component to the catalyst is deviated from the appropriate value and the deviation is reduced. Appears as a deviation between the catalyst bed temperature and the target bed temperature.

In order to determine whether or not such an abnormality has occurred, in Patent Document 1, the following abnormality diagnosis is performed. That is, during the temperature rise control for filter regeneration, the learning value is updated based on the catalyst bed temperature and the target value so that the learning value becomes a value corresponding to the difference between the two, and the learned value is not burned into the catalyst. Whether or not there is an abnormality is determined based on whether the learning value is within a predetermined range as well as being reflected in the component supply amount. Here, when the abnormality as described above has occurred, the learning value becomes a value outside the appropriate range, so that it can be determined that there is an abnormality based on the learned value.
JP 2003-172185 A (paragraphs [0065] to [0068])

  By the way, even if an attempt is made to raise the catalyst bed temperature to the target bed temperature by supplying the unburned fuel component to the exhaust system, the abnormality that the catalyst bed temperature does not reach the target bed temperature does not always occur permanently. It may occur temporarily instead of something. The learning value that is updated to be a value corresponding to the difference between the catalyst bed temperature and the target bed temperature is outside the predetermined range while the abnormality occurs.

  Such a temporary abnormality occurs when, for example, an addition valve that adds fuel to the exhaust system is used to supply unburned fuel components to the catalyst. A situation where deposits are attached around the nozzle hole of the valve can be mentioned. In this case, the amount of unburned fuel components supplied to the catalyst decreases as deposits adhere around the nozzle holes of the addition valve, and the catalyst bed temperature is raised to the target bed temperature by adding fuel from the addition valve. However, an abnormality that the catalyst bed temperature does not reach the target bed temperature occurs. However, even if deposits deposit around the nozzle hole of the addition valve due to the use of poor fuel, the deposit is likely to be removed from the nozzle hole in the process of consuming fuel. The occurrence of the abnormalities described above is temporary.

  However, in the abnormality diagnosis of Patent Document 1, the learning value updated so that the influence due to the temporary abnormality described above appears in the catalyst bed temperature and becomes a value corresponding to the difference between the catalyst bed temperature and the target bed temperature. If the value is out of the predetermined range, it is determined immediately that there is an abnormality based on that value, and therefore it is unavoidable to make an erroneous determination that there is an abnormality. That is, after the determination of the presence of abnormality is made, if the abnormality is resolved, the determination of the presence of abnormality is incorrect.

  The present invention has been made in view of such a situation, and an object of the present invention is to detect an abnormality in an internal combustion engine that can suppress erroneous determination of the presence of an abnormality when a temporary abnormality occurs. Is to provide.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, temperature increase control is performed to raise the temperature of the catalyst to the target bed temperature by supplying unburned fuel components to the catalyst provided in the exhaust system. An internal combustion engine abnormality that updates the learning value based on the catalyst bed temperature during temperature control and the target bed temperature so that the value corresponds to the difference between the two and determines whether there is an abnormality based on the learning value at the time of the update In the diagnostic device, every time the learning value is updated, a learning value determination unit that determines whether or not the learning value is a value outside the proper range, and a value outside the proper range of the learning value by the learning value determination unit And an abnormality determining means for determining that there is an abnormality when a determination that there is an abnormality is made a plurality of times each time the learning value is updated.

  Even if an attempt is made to control the catalyst bed temperature to the target bed temperature by supplying the unburned fuel component to the exhaust system, the abnormality that the catalyst bed temperature does not reach the target bed temperature and both are shifted is not necessarily permanent. It does not occur in a temporary manner and may occur temporarily. When such a temporary deviation between the catalyst bed temperature and the target bed temperature occurs, the learning value is updated so as to be a value corresponding to the deviation, and the learning value becomes a value outside the appropriate range. Sometimes. Here, if it is immediately determined that there is an abnormality when the learning value is outside the appropriate range, the determination that there is an abnormality will be incorrect if the temporary abnormality is resolved thereafter. It will be a thing. However, according to the above configuration, even if the learning value becomes a value out of the proper range at the time of updating, it is not determined that there is an abnormality unless it has occurred a plurality of times for each updating. Therefore, it is possible to suppress erroneously determining that there is an abnormality when an abnormality in which the catalyst bed temperature and the target bed temperature are temporarily shifted occurs.

According to a second aspect of the invention, in the first aspect of the invention, the internal combustion engine is provided with an addition valve for adding fuel upstream of the catalyst in the exhaust system.
According to the above configuration, the unburned fuel component is supplied to the catalyst provided in the exhaust system by adding the fuel from the addition valve. In this case, when poor fuel is used, deposits are likely to adhere around the nozzle hole of the addition valve, and the amount of fuel added from the addition valve is less than the appropriate value due to the adhesion of the deposit. Shifts to the lower side of the bed temperature. However, as described above, the deposit adhering around the nozzle hole of the addition valve is likely to be removed from the nozzle hole in the process of adding fuel, so there is an abnormality that the catalyst bed temperature deviates from the target bed temperature. It will be temporary. It can be suppressed that there is an abnormality based on the occurrence of such a temporary abnormality.

  According to a third aspect of the invention, in the first or second aspect of the invention, the internal combustion engine is provided with a filter for collecting fine particles in an exhaust system thereof, and the fine particles collected by the filter When the filter is regenerated to burn the same particulates so that the amount of deposits is less than a predetermined value, temperature increase control is performed to raise the catalyst to the target bed temperature by supplying unburned fuel components to the catalyst. It was.

  According to the above configuration, the filter regeneration is periodically performed so that the fine particles deposited on the catalyst are not more than a predetermined value. When the temperature increase control for filter regeneration is performed, the presence / absence of an abnormality can be determined at the same time, so that the chance of determining the presence / absence of the abnormality can be suppressed.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, when the learning value determining means determines that the learning value is outside the proper range, the count value is counted up, and the learning value is Counting means for resetting the count value to “0” when it is determined that the value is within an appropriate range, and the abnormality judging means is a judgment value that is set to a value equal to or greater than “2”. In this case, it is determined that there is an abnormality, and the counting means resets the count value to “0” even when the filter regeneration is completed.

  During the temperature rise control for filter regeneration, if an abnormality occurs in which the catalyst bed temperature temporarily does not reach the target bed temperature, the updated learning value becomes a value outside the appropriate range, and the count value is set by the counting means. Count up. However, if the temporary abnormality does not significantly affect the filter regeneration, the amount of accumulated particulates on the catalyst becomes less than the predetermined value before the count value exceeds the judgment value, and the filter regeneration is completed. There is. In this case, if the count value is kept at a value larger than “0”, a temporary abnormality occurs again during the temperature rise control for the next filter regeneration, and the learning value becomes out of the appropriate range. If this happens, the count value becomes equal to or greater than the determination value at an early stage, and it may be erroneously determined that there is an abnormality. However, according to the above configuration, since the count value is reset to “0” when the filter regeneration is completed, it is possible to avoid the occurrence of erroneous determination as described above.

  According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, when the learning value determination means determines that the learning value is outside the proper range, the count value is counted up, and the learning A counter that resets the count value to “0” when it is determined that the value is within a proper range, and the learning value is stable when the catalyst bed temperature is equal to or greater than a combustible value of the particulates. The abnormality determining means determines that there is an abnormality when the count value by the counting means is equal to or greater than a determination value set to a value of “2” or more, and the filter If the filter regeneration is not completed even if the elapsed time from the start of regeneration has exceeded the allowable time, it is determined that there is an abnormality regardless of the count value.

  During an increase in temperature control for filter regeneration, if an abnormality occurs in which the catalyst bed temperature does not reach the target bed temperature, the learned value may be updated to a value outside the appropriate range. The learning value is not updated unless the particle is stable at or above the combustible value of the fine particles deposited on the catalyst. Under such circumstances, the filter regeneration is continued while the count value does not exceed the determination value, in other words, it is not determined that there is an abnormality, even though an abnormality has occurred. Further, in the filter regeneration under such circumstances, it is highly possible that the filter regeneration cannot be completed because the combustion of the fine particles accumulated on the catalyst is difficult to proceed. According to the above configuration, if the filter regeneration is not completed even if the elapsed time from the filter regeneration start time has exceeded the allowable time, it is determined that there is an abnormality even if the count value is less than the determination value. Thus, it is possible to avoid the occurrence of a situation in which it is not determined that there is an abnormality even though an abnormality has actually occurred.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
FIG. 1 shows a configuration of an internal combustion engine 10 to which the abnormality diagnosis device of the present embodiment is applied. The internal combustion engine 10 is a diesel engine for automobiles equipped with a common rail fuel injection device.

  An intake passage 12 constituting the intake system of the internal combustion engine 10 and an exhaust passage 14 constituting the exhaust system of the engine 10 are each connected to a combustion chamber 13 of a cylinder of the internal combustion engine 10. An air flow meter 16 and an intake throttle valve 19 are provided in the intake passage 12. The exhaust passage 14 is provided with a NOx catalytic converter 25, a PM filter 26, and an oxidation catalytic converter 27 in order from the upstream side.

  The NOx catalytic converter 25 carries an NOx storage reduction catalyst. The NOx catalyst stores NOx in the exhaust when the oxygen concentration of the exhaust is high, and releases the stored NOx when the oxygen concentration of the exhaust is low. Further, the NOx catalyst reduces and purifies the released NOx if there is sufficient unburned fuel component as a reducing agent at the time of releasing the NOx.

  The PM filter 26 is made of a porous material and collects fine particles (PM) mainly composed of soot in the exhaust gas. Similarly to the NOx catalytic converter 25, the PM filter 26 also carries an NOx storage reduction catalyst so that NOx in the exhaust gas can be purified. Further, the collected PM is burned (oxidized) and removed by a reaction triggered by the NOx catalyst.

The oxidation catalyst converter 27 carries an oxidation catalyst. This oxidation catalyst oxidizes and purifies hydrocarbons (HC) and carbon monoxide (CO) in the exhaust.
In addition, on the upstream side and the downstream side of the PM filter 26 in the exhaust passage 14, an inlet gas temperature sensor 28 that detects the inlet gas temperature that is the temperature of the exhaust gas flowing into the PM filter 26, and the exhaust gas after passing through the PM filter 26. An outgas temperature sensor 29 for detecting an outgas temperature, which is a temperature, is provided. The exhaust passage 14 is provided with a differential pressure sensor 30 for detecting a differential pressure between the exhaust upstream side of the PM filter 26 and the exhaust downstream side thereof. Further, two air-fuel ratio sensors 31 and 32 for detecting the air-fuel ratio of the exhaust are arranged on the exhaust gas upstream side of the NOx catalytic converter 25 and between the PM filter 26 and the oxidation catalytic converter 27, respectively. It is installed.

  Further, the internal combustion engine 10 is provided with an exhaust gas recirculation (hereinafter referred to as EGR) device that recirculates a part of the exhaust gas to the air in the intake passage 12. The EGR device includes an EGR passage 33 that allows the exhaust passage 14 and the intake passage 12 to communicate with each other. The most upstream part of the EGR passage 33 is connected to the exhaust passage 14. An EGR valve 36 is provided in the EGR passage 33. The most downstream portion of the EGR passage 33 is connected to the downstream side of the intake throttle valve 19 in the intake passage 12.

  On the other hand, an injector 40 for injecting fuel to be used for combustion in the combustion chamber 13 is disposed in the combustion chamber 13 of each cylinder of the internal combustion engine 10. The injector 40 of each cylinder is connected to a common rail 42 via a high pressure fuel supply pipe 41. High pressure fuel is supplied to the common rail 42 through a fuel pump 43. The pressure of the high-pressure fuel in the common rail 42 is detected by a rail pressure sensor 44 attached to the common rail 42. Further, low pressure fuel is supplied from the fuel pump 43 to the addition valve 46 through the low pressure fuel supply pipe 45.

  Various controls of the internal combustion engine 10 are performed by the electronic control unit 50. The electronic control unit 50 includes a CPU that executes various arithmetic processes related to engine control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores CPU arithmetic results, and signals between the outside The input / output port for inputting / outputting is provided.

  In addition to the above-described sensors, the input port of the electronic control unit 50 includes an NE sensor 51 that detects the engine speed, an accelerator sensor 52 that detects the accelerator operation amount, and a throttle valve sensor that detects the opening of the intake throttle valve 19. 53, an intake air temperature sensor 54 for detecting the intake air temperature of the internal combustion engine 10, a water temperature sensor 55 for detecting the cooling water temperature of the engine 10, and the like are connected. The output port of the electronic control unit 50 is connected to drive circuits such as the intake throttle valve 19, the EGR valve 36, the injector 40, the fuel pump 43, and the addition valve 46.

  The electronic control unit 50 outputs a command signal to the drive circuit of each device connected to the output port according to the engine operating state grasped from the detection signal input from each sensor. Thus, the opening control of the intake throttle valve 19, EGR control based on the opening control of the EGR valve 36, control of the fuel injection amount, fuel injection timing, and fuel injection pressure from the injector 40, Various controls such as fuel addition control are performed by the electronic control unit 50.

  In the present embodiment configured as described above, in order to prevent clogging due to PM in the NOx catalytic converter 25 and the PM filter 26, PM accumulated in the exhaust system such as the NOx catalytic converter 25 and the PM filter 26 is burned ( Filter regeneration is performed by oxidizing and purifying. In order to perform such filter regeneration, it is necessary to sufficiently raise the temperature of the NOx catalytic converter 25 and the PM filter 26. For this reason, when filter regeneration is performed, the unburnt fuel component is supplied to the NOx catalyst of the NOx catalytic converter 25 and the PM filter 26, so that the catalyst bed temperature is a value necessary for the combustion of the PM (for example, 600 to 700 ° C.). The temperature raising control is performed to raise the temperature to. Note that the supply of the unburned fuel component to the catalyst in the temperature rise control is performed by adding fuel to the exhaust from the addition valve 46 or the like.

Incidentally, in the present embodiment, the temperature increase control for filter regeneration is started when all of the following conditions are satisfied.
-When filter regeneration is requested. The filter regeneration request here is made when the PM accumulation amount in the exhaust system estimated from the engine operating state exceeds an allowable value and the occurrence of clogging in the PM filter 26 or the like is confirmed.

  -The detection value (input gas temperature thci) of the said input gas temperature sensor 28 is more than the minimum temperature (for example, 150 degreeC) of temperature rise control implementation. Further, the catalyst bed temperature of the NOx catalyst estimated from the history of the engine operation state, the detected value of the inlet gas temperature sensor 28, and the detected value of the outlet gas temperature sensor 29 is equal to or higher than the lower limit temperature of the temperature increase control. These lower limit temperatures are respectively set to an exhaust temperature and a lower limit value of the catalyst bed temperature that can cause an oxidation reaction sufficient to raise the catalyst bed temperature with the supply of the unburned fuel component.

The detection value of the inlet gas temperature sensor 28 is less than the upper limit value C of the temperature range in which the catalyst can be prevented from being overheated due to heat generation accompanying the temperature rise control.
The detection value of the outgas temperature sensor 29 is less than the upper limit value D of the temperature range that can avoid the excessive temperature rise of the catalyst due to the heat generation accompanying the temperature rise control.

  ・ Addition of fuel to the exhaust is permitted. In other words, the engine is in an operating state in which exhaust fuel addition can be allowed. In this internal combustion engine 10, addition of exhaust fuel is permitted if the cylinder discrimination is completed and the output is not limited when the engine is not stalling.

  When the PM regeneration amount is reduced to a predetermined value (for example, “0”) by executing the filter regeneration through the temperature increase control, it is determined that the filter regeneration is completed, and the temperature increase control for the filter regeneration is completed. Be made.

Next, an outline of the temperature rise control will be described with reference to the time chart of FIG.
The catalyst bed temperature T during the temperature rise control is a value that is increased by the amount of heat generated by the oxidation reaction based on the fuel addition from the addition valve 46 with respect to the catalyst inlet exhaust temperature Tb that is the exhaust temperature upstream of the NOx catalytic converter 25. It will be. In the temperature increase control, the target bed temperature Tt of the catalyst is increased stepwise, for example, 600, 630, and 650, and the catalyst from the addition valve 46 is increased so that the catalyst bed temperature T increases toward the target bed temperature Tt. An unburned fuel component is supplied to the catalyst through fuel addition. However, when the exhaust temperature of the internal combustion engine 10 is low and the exhaust flow rate is small, the oxidation reaction of the unburned fuel component does not proceed even if the fuel addition from the addition valve 46 is increased, and the catalyst bed temperature T may be raised. Therefore, the target bed temperature Tt may be temporarily lowered to prevent unnecessary fuel addition from the addition valve 46.

  Fuel addition from the addition valve 46 is started based on a change (timing T1) of the addition permission flag F1 to “1 (permitted)” shown in FIG. The addition permission flag F1 is set to “0” after being set to “1”. When fuel addition from the addition valve 46 is started, intermittent fuel addition from the addition valve 46 is performed according to the addition pulse shown in FIG. The fuel addition time a and the fuel addition stop time b in such intermittent fuel addition are the temperature difference ΔTb between the target bed temperature Tt and the catalyst inlet exhaust temperature Tb and the internal combustion engine detected by the air flow meter 16. 10 gas flow rate Ga (corresponding to the exhaust flow rate of the internal combustion engine 10). As the catalyst inlet exhaust temperature Tb, for example, a value estimated based on the detection values of the inlet gas temperature sensor 28 and the outlet gas temperature sensor 29 can be used. The intermittent fuel addition started as described above is continued until a predetermined number of times of fuel addition is executed, and is stopped after the fuel addition is performed for that number of times (timing T2).

  After the start of fuel addition from the addition valve 46, every time a predetermined time, for example, 16 ms elapses based on the drive state of the addition valve 46, 16 ms exothermic fuel that is the amount of fuel added from the addition valve 46 during the 16 ms. A quantity Q is calculated. By accumulating this 16 ms exothermic fuel amount Q based on the equation “ΣQ ← previous ΣQ + Q (1)” for each calculation, the total addition amount from the addition valve 46 from the fuel addition start time (T1), in other words, For example, an exothermic fuel amount integrated value ΣQ representing the total fuel amount contributing to the heat generation due to the oxidation reaction is calculated. The exothermic fuel amount integrated value ΣQ calculated in this way increases rapidly during the addition period A, which is the period from the start to the end of fuel addition, as shown by the solid line in FIG. The increase during the fuel addition suspension period B is suppressed.

  On the other hand, after the start of fuel addition from the addition valve 46, the amount of fuel to be added from the addition valve 46 during the predetermined time (16 ms), in other words, the catalyst bed temperature T reaches the target bed temperature Tt. A required fuel amount Qr of 16 ms, which is the amount of fuel added necessary for the control, is calculated. This 16 ms required fuel amount Qr is calculated using the temperature difference ΔTb between the target bed temperature Tt and the catalyst inlet exhaust temperature Tb and the gas flow rate Ga of the internal combustion engine 10. The calculated 16 ms required fuel amount Qr increases as the catalyst inlet exhaust temperature Tb indicated by the solid line L2 in FIG. 2B is lower than the target bed temperature Tt. Then, the 16 ms required fuel amount Qr is accumulated every calculation based on the formula “ΣQr ← previous ΣQr + Qr (2)”, so that the average value of the catalyst bed temperature T is required to be the target bed temperature Tt. A required fuel amount integrated value ΣQr representing the fuel amount from the fuel addition start time (T1) is calculated. The calculated required fuel amount integrated value ΣQr increases gradually as compared with the increase (solid line) of the exothermic fuel amount integrated value ΣQ, as indicated by a broken line in FIG.

  When the required fuel amount integrated value ΣQr becomes equal to or greater than the exothermic fuel amount integrated value ΣQ (timing T3), the addition permission flag F1 changes to “1 (permission)”, and intermittent fuel addition from the addition valve 46 is performed. Be started. At this time, since the addition of the fuel for the heat generation fuel amount integrated value ΣQ after the timing T1 has been completed from the addition valve 46, the heat generation fuel amount integration value ΣQ is subtracted from the required fuel amount integration value ΣQr. Furthermore, the exothermic fuel amount integrated value ΣQ is cleared and becomes “0”. Then, along with the start of intermittent fuel addition from the addition valve 46, the process shifts again to the addition period A. When the addition period A ends, the process shifts to the pause period B. Therefore, the addition period A and the pause period B are repeated during the temperature rise control.

  During the temperature increase control, the 16 ms required fuel amount Qr is calculated to be larger as the catalyst inlet exhaust temperature Tb is further away from the target bed temperature Tt. The integrated value ΣQr increases rapidly. As a result, the time required for the required fuel amount integrated value ΣQr to be equal to or greater than the exothermic fuel amount integrated value ΣQ is shortened, and the suspension period B is shortened. Further, the 16 ms required fuel amount Qr is calculated to be smaller as the catalyst inlet exhaust temperature Tb approaches the target bed temperature Tt, and the increase in the required fuel amount integrated value ΣQr is moderated. As a result, the time required for the required fuel amount integrated value ΣQr to be equal to or greater than the exothermic fuel amount integrated value ΣQ becomes longer, and the suspension period B becomes longer.

  As described above, by changing the length of the suspension period B according to the deviation state of the catalyst inlet exhaust temperature Tb from the target bed temperature Tt, the average amount of fuel added from the addition valve 46 per unit time is changed accordingly. The value changes. As a result, the catalyst bed temperature T changes, for example, as indicated by the solid line L1 in FIG. 2B, and the fluctuation center of the catalyst bed temperature T that increases or decreases is controlled to the target bed temperature Tt.

  Next, the fuel addition control procedure by the addition valve 46 during the temperature rise control will be described with reference to the flowcharts of FIGS. 3 and 4 showing the fuel addition control routine. This fuel addition control routine is periodically executed through the electronic control unit 50, for example, with a time interruption every predetermined time (in this embodiment, 16 ms).

  In this routine, it is first determined in step S101 in FIG. 3 whether or not the temperature raising control is being performed. If the determination is affirmative, the routine proceeds to step S102, where the 16 ms required fuel amount Qr is calculated based on the temperature difference ΔTb between the target bed temperature Tt and the catalyst inlet exhaust temperature Tb and the gas flow rate Ga. The subsequent processes in steps S103 and S104 are for correcting the 16 ms required fuel amount Qr by the learned value K for eliminating the steady deviation between the catalyst bed temperature T and the target bed temperature Tt.

  Specifically, as the process of step S103, the learning value K stored in the nonvolatile RAM of the electronic control device 50 is read. This learning value K is calculated as a value corresponding to a steady deviation between the catalyst bed temperature T and the target bed temperature Tt by another routine, and is stored in the nonvolatile RAM. In the process of step S104, a value obtained by multiplying the 16 ms required fuel amount Qr by the learning value K is set as a new 16 ms required fuel amount Qr.

  The 16 ms required fuel amount Qr calculated by the processing of steps S102 to S104 is accumulated based on the equation “ΣQr ← previous ΣQr + Qr (2)” in step S105. By this accumulation, the required fuel amount integrated value ΣQr described above can be obtained. Then, it progresses to step S106 of FIG.

  In the process of step S106, the 16 ms exothermic fuel amount Q is calculated based on the driving state of the addition valve 46. Subsequently, as the processing of step S107, the calculated 16 ms exothermic fuel amount Q is accumulated based on the formula “ΣQ ← previous ΣQ + Q (1)”. As a result of this accumulation, the above-mentioned heat generating fuel amount integrated value ΣQ can be obtained.

  In the process of step S108, it is determined whether or not the required fuel amount integrated value ΣQr is equal to or greater than the exothermic fuel amount integrated value ΣQ. If the determination is affirmative, the process proceeds to step S109, and the addition permission flag F1 is set to “1 (permitted)”. As a result, intermittent fuel addition from the addition valve 46 is started. Thereafter, as a process of step S110, a value obtained by subtracting the exothermic fuel amount integrated value ΣQ from the required fuel amount integrated value ΣQr is set as a new required fuel amount integrated value ΣQr. Furthermore, the heat generation fuel amount integrated value ΣQ is cleared and set to “0” in the process of step S111.

Next, an outline of a procedure for calculating the learning value K used in step S103 of FIG. 3 will be described with reference to FIGS.
FIG. 5 shows a state in which a steady deviation occurs between the catalyst bed temperature T and the target bed temperature Tt during the temperature rise control, and the catalyst bed temperature T (solid line) does not rise to the target bed temperature Tt (broken line). ing. The reason why such a steady deviation occurs is, for example, a deviation from an appropriate value of the fuel addition amount due to an abnormality such as clogging of the addition valve 46, or a deviation from an appropriate value of the gas flow rate Ga due to an abnormality in the air flow meter 16. can give.

  The learning value K is calculated as a value corresponding to a steady deviation between the catalyst bed temperature T (catalyst bed temperature average value Tave) and the target bed temperature Tt, and is used to correct the 16 ms required fuel amount Qr. . When the 16 ms required fuel amount Qr is corrected using the learning value K, the increase in the required fuel amount integrated value ΣQr is accelerated or delayed, so that the required fuel amount integrated value ΣQr becomes greater than or equal to the exothermic fuel amount integrated value ΣQ. The timing that changes. As a result, the pause period B increases and decreases, and the average value of the amount of fuel added from the addition valve 46 per unit time changes. Thus, the learning value K is reflected in the supply of unburned fuel components to the catalyst.

  Here, when a steady shift between the catalyst bed temperature average value Tave and the target bed temperature Tt as shown in FIG. 5 occurs, the learning value K corresponding to the shift is used as an unburned fuel component for the catalyst. FIG. 6 and FIG. 7 show the difference between the case where it is not reflected and the case where it is reflected.

  The broken line in FIG. 6 shows the transition of the required fuel amount integrated value ΣQr when the learned value K is not reflected. In this case, the learning value K is not multiplied by the 16 ms required fuel amount Qr, and the 16 ms required fuel amount Qr includes a deviation from an appropriate value due to clogging of the addition valve 46 or an abnormality of the air flow meter 16. . As a result, the required fuel amount integrated value ΣQr gradually increases by the amount of deviation from the appropriate value of the 16 ms required fuel amount Qr, and the required fuel amount integrated value ΣQr becomes equal to or greater than the exothermic fuel amount integrated value ΣQ. Will be late. As described above, the pause period B becomes longer and the average value of the amount of fuel added from the addition valve 46 per unit time becomes smaller, and the catalyst bed temperature average value Tave and the target bed temperature Tt as shown in FIG. There will be a steady shift between the two.

  On the other hand, the broken line in FIG. 7 shows the transition of the required fuel amount integrated value ΣQr when the learned value K is reflected. In this case, the learning value K is multiplied by the 16 ms required fuel amount Qr, and the deviation from the appropriate value due to the clogging of the addition valve 46 or the abnormality of the air flow meter 16 is removed from the 16 ms required fuel amount Qr. As a result, the required fuel amount integrated value ΣQr does not gradually increase by the amount of deviation from the appropriate value of the 16 ms required fuel amount Qr, and increases more rapidly than the broken line in FIG. The timing at which becomes the heat generation fuel amount integrated value ΣQ or more is advanced. As described above, the pause period B is shortened, the average value of the amount of fuel added from the addition valve 46 per unit time is increased, the catalyst bed temperature average value Tave is increased, and the catalyst bed temperature average value Tave and the target bed are increased. The steady deviation from the temperature Tt is eliminated.

  FIG. 8 is a time chart showing how the learning value K changes when the steady deviation between the catalyst bed temperature average value Tave and the target bed temperature Tt is eliminated. Now, as indicated by the broken line and the alternate long and short dash line in FIG. 8A, it is assumed that there is a steady deviation that the catalyst bed temperature average value Tave becomes a lower value with respect to the target bed temperature Tt.

The learning value K as a value corresponding to such a deviation is calculated using the 16 ms required fuel amount Qr (see FIG. 2C) and the 16 ms estimated heat generation fuel amount Q ′.
Here, the 16 ms estimated exothermic fuel amount Q ′ is calculated every 16 ms, and is obtained from the addition valve 46 during 16 ms in order to obtain the increase amount ΔT ′ of the catalyst bed temperature T from the catalyst inlet exhaust temperature Tb. This is an estimated value of the added fuel amount, in other words, an estimated value of the fuel amount that contributed to the heat generation in 16 ms for obtaining the increase amount ΔT ′. The 16 ms estimated exothermic fuel amount Q ′ is calculated based on the increase amount ΔT ′ that is the difference between the catalyst bed temperature T and the catalyst inlet exhaust temperature Tb, and the gas flow rate Ga. As the catalyst bed temperature T, for example, a value estimated based on detection values of the incoming gas temperature sensor 28 and the outgoing gas temperature sensor 29 can be used. The 16 ms required fuel amount Qr represents the amount of fuel to be added from the addition valve 46 during 16 ms in order to raise the catalyst bed temperature T from the catalyst inlet exhaust temperature Tb to the target bed temperature Tt. As described above, it is calculated based on the temperature difference ΔTb between the bed temperature Tt and the catalyst inlet exhaust temperature Tb and the gas flow rate Ga.

  The ratio Qr / Q ′ between the 16 ms required fuel amount Qr and the 16 ms estimated exothermic fuel amount Q ′ is the catalyst bed relative to the target bed temperature Tt at the time of calculation of the 16 ms required fuel amount Qr and the 16 ms estimated exothermic fuel amount Q ′. The value corresponds to the temperature T shift. Therefore, by calculating an average value of the ratio Qr / Q 'over a predetermined period, the average value becomes a value corresponding to a steady deviation of the catalyst bed temperature average value Tave from the target bed temperature Tt. An average value of the ratio Qr / Q ′ over a predetermined period is calculated as a learned value K, and the learned value K is non-volatile based on the target bed temperature Tt being in a stable state at a value that allows PM combustion. Stored (updated) in RAM.

  If the learning value K is updated at the timings T4, T5, and T6 in the drawing, for example, the learning value K stored in the non-volatile RAM changes as shown in FIG. 8B. In addition, the pause period B in the temperature rise control is gradually shortened. As a result, the average value of the amount of fuel added from the addition valve 46 becomes large, and the catalyst bed temperature average value Tave rises to the target bed temperature Tt as shown in FIG. The gap is resolved.

  Next, a detailed procedure for calculating and updating the learning value K will be described with reference to a flowchart of FIG. 9 showing a learning value updating routine. This learning value update routine is periodically executed through the electronic control unit 50, for example, with a time interrupt every predetermined time (16 ms in the present embodiment).

  In this routine, it is first determined whether or not the calculation of the learning value K is permitted (S201). Note that calculation of the learning value K is permitted when, for example, all of the following conditions are satisfied over a long period of time.

-Temperature rise control is in progress.-A state where the gas flow rate Ga is low has not continued for a long time such as 50 s.-It is not immediately after the target bed temperature Tt becomes higher than before.

-Immediately after updating the learning value K, in other words, not immediately after reflecting the new learning value K in the fuel addition.
The decrease in the target bed temperature Tt is not continued, for example, the decrease in the target bed temperature Tt is less than 15 s.

-Fuel addition from the addition valve 46 is not prohibited. The fuel addition is prohibited, for example, when the catalyst bed temperature T is excessively increased.
-The inlet gas temperature sensor 28 and the outlet gas temperature sensor 29 are not abnormal.

  If a negative determination is made in step S201, calculation of the learning value K is prohibited (S206). If the determination is affirmative, the ratio Qr / Q ′ of both is obtained based on the 16 ms required fuel amount Qr and the 16 ms estimated heat generation fuel amount Q ′ calculated every 16 ms, and the ratio Qr / Q ′ is determined within a predetermined period. The average value is calculated as the learning value K (S202). When the calculation of the learning value K continues for a predetermined time or longer (S203: YES), and the target bed temperature Tt is in a stable state at a value not lower than the combustible value of PM (for example, 600 ° C. or higher) (S204: YES), the calculated learning value K is stored (updated) in a non-volatile RAM provided in the electronic control unit 50. Thus, the learning value K stored in the nonvolatile RAM is reflected in the fuel addition from the addition valve 46.

  By the way, the learning value K corresponds to a deviation between the catalyst bed temperature T (catalyst bed temperature average value Tave) that is a parameter that is changed by addition of fuel from the addition valve 46 and the target bed temperature Tt that is the target value. Value. For this reason, in the learning value K, the lower the catalyst bed temperature average value Tave is, the further away from “1.0” is, the more the catalyst bed temperature average value Tave is lower than the target bed temperature Tt. The higher the value, the farther away from “1.0”.

  Here, if an abnormality that the catalyst bed temperature average value Tave cannot be adjusted to the target bed temperature Tt occurs during the temperature rise control, the learning value K becomes excessively large or small. For example, when the fuel supply system for fuel addition is clogged, the amount of fuel added from the addition valve 46 is reduced and the catalyst bed temperature average value Tave is smaller than the target bed temperature Tt. Therefore, a situation may occur in which the learning value K is excessively larger than “1.0”. For this reason, it is determined whether or not there is an abnormality using the change in the learning value K accompanying the occurrence of the abnormality as described above. More specifically, when the learning value K is updated, the learning value K is determined in a predetermined range, for example, It may be possible to determine whether there is an abnormality based on whether the value is out of the range of “0.90 to 1.4”.

However, the abnormality that the catalyst bed temperature average value Tave cannot be adjusted to the target bed temperature Tt does not necessarily occur permanently, and may occur only temporarily.
Incidentally, when deposits are attached around the nozzle hole of the addition valve 46 due to the use of poor fuel, the fuel addition amount of the addition valve 46 becomes smaller than the appropriate value, so the catalyst bed temperature average value Tave is the target. The temperature becomes lower than the bed temperature Tt, and an abnormality that the catalyst bed temperature average value Tave cannot be adjusted to the target bed temperature Tt occurs. However, in this case, the deposit may be taken from around the nozzle hole in the process of adding fuel from the addition valve 46, so that even if the above-described abnormality occurs, it is temporary.

  In addition, when the gas flow rate Ga detected by the air flow meter 16 becomes a value deviated from the actual gas flow rate due to the adhesion of foreign matter to the detection unit of the air flow meter 16, the gas flow rate Ga is caused accordingly. The 16 ms required fuel amount Qr calculated based on the value may be larger than an appropriate value. When the 16 ms required fuel amount Qr becomes larger than the appropriate value in this way, the suspension period B during the temperature increase control is made shorter than the appropriate value, so the catalyst bed temperature average value Tave becomes higher than the target bed temperature Tt, An abnormality that the catalyst bed temperature average value Tave cannot be adjusted to the target bed temperature Tt occurs. However, in this case, in the process in which air flows in the vicinity of the detection unit of the air flow meter 16, foreign matter attached to the detection unit may be taken from around the detection, so even if the above-described abnormality occurs, It will be temporary.

  Without considering these things, if the learning value K at the time of updating once falls outside the appropriate range (timing T7 in FIG. 10), if it is immediately determined that there is an abnormality, the abnormality is temporarily If the learning value K returns to within the appropriate range when the learning value K is later updated and the learning value K is updated (timing T8), the determination that there is an abnormality is incorrect. .

  Therefore, in this embodiment, each time the learning value K is updated, it is determined whether or not the learning value K is outside the appropriate range. If the learning value K is outside the appropriate range, the count value of the counter C is set. The count value of the counter C is reset to the initial value “0” if the learning value K is a value within the appropriate range. (A) and (b) of FIG. 11 show the transition of the learning value K for each update, and the transition of the counter value of the counter C associated therewith. In this counter C, the initial value of the counter value is “0”, and when the learning value K becomes a value outside the appropriate range for each update, the count value is incremented from the initial value “0” to “1”. It will increase. When the counter value of the counter C is equal to or greater than a determination value (for example, “3”) that is a value equal to or greater than “2” (timing T10), in other words, the learning value K is outside the proper range. Is continued for a plurality of times (three times in this embodiment) every time the learning value K is updated, it is determined that there is an abnormality.

  In this case, before the count value of the counter C becomes equal to or greater than the determination value, the abnormality is resolved and the learning value K returns to a value within the appropriate range as shown by a two-dot chain line in FIG. T9) Since the count value is reset to the initial value “0” as indicated by a two-dot chain line in FIG. 11B, it is not determined that there is an abnormality. That is, even if the learning value K at the time of updating becomes a value outside the appropriate range, it is not determined that there is an abnormality unless it has occurred three times after each updating. Therefore, when an abnormality that the catalyst bed temperature average value Tave cannot be adjusted to the target bed temperature Tt temporarily occurs, it is possible to suppress erroneously determining that there is an abnormality.

  Next, the procedure for determining the presence or absence of the abnormality will be described with reference to the flowchart of FIG. 12 showing the abnormality diagnosis routine. This abnormality diagnosis routine is periodically executed through the electronic control unit 50, for example, with a time interruption every predetermined time.

  In this routine, the count value of the counter C is set based on the magnitude of the learning value K on condition that the temperature rise control is being performed (S301: YES) and the learning value K is being updated (S302: YES). Processing for changing (steps S303 to S305) is executed. Specifically, it is first determined whether or not the learning value K is outside the appropriate range (S303). If the determination is affirmative, the count value of the counter C is incremented by “1” (S304). If the determination is negative, the count value is reset to the initial value “0” (S305). The count value of the counter C is stored in the non-volatile RAM of the electronic control unit 50 every time the learning value K is updated, and the value stored in the non-volatile RAM when the operation of the internal combustion engine 10 is started next time is the initial value. Set as

  Subsequently, it is determined whether or not the count value of the counter C is equal to or larger than a determination value (“3” in this embodiment) (S306). If the determination is affirmative, it is determined that there is an abnormality, and “1 (abnormal)” is stored as an abnormality flag F2 in a predetermined area of the nonvolatile RAM of the electronic control unit 50 (S307). Further, a warning lamp provided in a driver's seat of an automobile on which the internal combustion engine 10 is mounted is turned on (S308), and a warning that an abnormality has occurred is given to the driver.

  On the other hand, if a negative determination is made in step S306, it is determined whether or not the filter regeneration is incomplete (S309), and if a negative determination (filter regeneration complete) is made in step S309, the count value of the counter C is increased. The initial value is reset to “0” (S310). Here, even if the learning value K at the time of update becomes a value outside the proper range as shown in FIG. 13A due to the abnormality, if the abnormality does not affect the filter regeneration so much, FIG. As shown in (b), when the count value of the counter C reaches, for example, “2” before reaching the determination value (“3”), the filter regeneration may be completed (timing T11). In such a case, the count value of the counter C is reset to the initial value “0”.

  Further, when an affirmative determination is made in step S309 in FIG. 12 and it is determined that the filter regeneration is incomplete, it is determined whether or not an allowable time (for example, 1 hour) has elapsed since the start of the filter regeneration. (S311). If an affirmative determination is made in step S311, it is determined that there is an abnormality, and the processes in steps S307 and S308 are executed in order. Here, when the learning value K is updated to a value outside the proper range as shown in FIG. 14A due to an abnormality, the learning value K may be updated to a value outside the proper range thereafter. However, if the target bed temperature Tt is not stable beyond the value at which PM combustion is possible, the learning value K is not updated to a value outside the appropriate range. Under such circumstances, the PM combustion during the filter regeneration is difficult to proceed, so the PM accumulation amount does not decrease to “0”, and there is a high possibility that the filter regeneration will not be completed. As a result, as shown in FIG. 14B, the elapsed time from the start of filter regeneration becomes equal to or longer than the allowable time without the count value of the counter C reaching the determination value (timing T12). Based on this, it is determined that there is an abnormality, “1 (abnormal)” is stored as an abnormality flag F2 in the nonvolatile RAM of the electronic control unit 50, and a warning lamp is lit.

According to the embodiment described in detail above, the following effects can be obtained.
(1) During the temperature increase control for filter regeneration, an abnormality that the catalyst bed temperature average value Tave cannot be adjusted to the target bed temperature Tt occurs. However, such abnormalities do not always occur permanently, but may occur only temporarily. Here, when the learning value K at the time of updating once falls outside the appropriate range, if it is immediately determined that there is an abnormality, the abnormality is temporary and the abnormality is resolved later. If the learned value K returns to the appropriate range when the learned value K is updated, the determination that there is an abnormality is incorrect. However, the determination that there is an abnormality in this embodiment is made only when the determination that the learning value K at the time of updating has become a value outside the appropriate range continues three times for each update. More specifically, if the learning value K at the time of updating is a value outside the proper range, the counter C is incremented, and if the learned value K is within the proper range, the counter C is reset to the initial value “0”. When the value reaches the determination value (“3” in this embodiment), it is determined that there is an abnormality. Therefore, when an abnormality that the catalyst bed temperature average value Tave cannot be adjusted to the target bed temperature Tt temporarily occurs, it is possible to suppress erroneously determining that there is an abnormality.

  (2) The learning value K necessary for determining the presence or absence of abnormality is updated during the temperature increase control for filter regeneration. This filter regeneration is periodically performed every time the PM accumulation amount increases to an allowable value or more with the operation of the internal combustion engine 10. Therefore, the learning value K can be updated each time the temperature increase control for filter regeneration is performed periodically, so that it is possible to determine whether there is an abnormality at the time of the update, and to make the determination. It is possible to suppress a decrease in opportunities.

  (3) During the temperature increase control for filter regeneration, when an abnormality occurs in which the catalyst bed temperature average value Tave temporarily does not reach the target bed temperature Tt, the updated learned value K becomes a value outside the appropriate range. Thus, the count value of the counter C is counted up. However, if the temporary abnormality does not significantly affect the filter regeneration, the PM accumulation amount may become “0” before the counter value becomes equal to or greater than the determination value, and the filter regeneration may be completed. In this case, if the count value is kept at a value larger than “0” (for example, “2”), a temporary abnormality occurs again during the temperature rise control for the next filter regeneration, and the learning value K becomes smaller. When the value is out of the proper range, the count value becomes equal to or higher than the determination value at an early stage, and there is a possibility that it is erroneously determined that there is an abnormality. However, since the counter value of the counter C is reset to the initial value “0” when the filter regeneration is completed, it is possible to avoid the occurrence of the erroneous determination as described above.

  (4) During the temperature increase control for filter regeneration, when an abnormality occurs in which the catalyst bed temperature average value Tave temporarily does not reach the target bed temperature Tt, the learning value K is updated to a value outside the appropriate range. Even if there is a possibility that the target bed temperature Tt is not stable above the value that allows PM combustion, the learning value K is not updated to a value outside the appropriate range. Under such circumstances, despite the occurrence of an abnormality, the filter regeneration is continued without the count value of the counter C being equal to or higher than the determination value, in other words, the determination that there is an abnormality is not made. Become. Further, in the filter regeneration under such a situation, the accumulated PM does not easily burn, so the PM accumulation amount does not decrease to “0”, and there is a high possibility that the filter regeneration cannot be completed. However, if the filter regeneration is not completed even if the elapsed time from the start of the filter regeneration exceeds the allowable time, it is determined that there is an abnormality even if the count value of the counter C does not reach the determination value. It is possible to avoid the occurrence of a situation in which it is not determined that there is an abnormality despite the occurrence of an abnormality.

  (5) The counter value of the counter C is stored in the non-volatile RAM of the electronic control unit 50, and the value stored in the non-volatile RAM is set as the initial value when the internal combustion engine 10 is started next time. Assuming that the counter value of the counter C is reset to the initial value “0” every time the internal combustion engine 10 is stopped, it is determined whether there is an abnormality in an operating situation in which the internal combustion engine 10 is repeatedly stopped and started frequently. There are fewer opportunities to make a determination, and even if an abnormality actually occurs, it may not be possible to determine that there is an abnormality. Further, along with the delay in determining whether there is an abnormality, PM may be excessively accumulated due to filter regeneration not being properly performed due to the abnormality, and the PM filter or the like may be replaced. However, these problems are suppressed by the processing of the counter value of the counter C when the internal combustion engine 10 is started.

In addition, the said embodiment can also be changed as follows, for example.
When the elapsed time from the start of filter regeneration is equal to or greater than the allowable time, it is determined that there is an abnormality regardless of the count value of the counter C, but such a determination is not necessarily required.

Although the count value of the counter C is reset to the initial value “0” when the filter regeneration is completed, such reset is not necessarily performed.
In an internal combustion engine that controls the temperature rise by adding fuel from the addition valve 46, the most frequent cause of temporary abnormality is temporary deposits on the nozzle holes of the addition valve 46. It is guessed. In consideration of this, the count value of the counter C may be counted up only when the learning value K at the time of update deviates from the appropriate range.

  In an internal combustion engine equipped with a NOx catalyst, recovery of S poisoning released from sulfur components stored in the NOx catalyst is performed, and temperature rise control is also performed to realize the recovery of S poisoning. It is also possible to determine whether or not there is an abnormality during temperature increase control for such S poison recovery.

As a determination value used for determining whether there is an abnormality, a value of “2” or an integer value of “4” or more may be used instead of the value of “3” in the above embodiment.
The unburned fuel component may be supplied to the exhaust system by sub-injection (after-injection) performed in the exhaust stroke or the expansion stroke after the fuel supplied from the injector 40 for combustion in the combustion chamber 13 is injected. . In this case, the addition valve 46 may be omitted.

1 is a schematic diagram showing an entire internal combustion engine to which an abnormality diagnosis device of an embodiment is applied. (A)-(d) are the change of the addition pulse for driving the addition valve during the temperature rise control for filter regeneration, the change of the catalyst bed temperature T and the catalyst inlet exhaust temperature Tb, and the integrated values ΣQr and ΣQ. The time chart which shows transition and the setting aspect of the addition permission flag F1. The flowchart which shows the control procedure of the fuel addition by the addition valve in temperature rising control. The flowchart which shows the control procedure of the fuel addition by the addition valve in temperature rising control. 4 is a time chart showing a state in which a steady deviation occurs between a catalyst bed temperature T (catalyst bed temperature average value Tave) and a target bed temperature Tt during temperature rise control. The time chart which shows transition of integrated value (SIGMA) Qr and (SIGMA) Q when the learning value K is not reflected. The time chart which shows transition of integrated value (SIGMA) Qr and (SIGMA) Q when the learning value K is reflected. (A) is a time chart showing the transition of both the catalyst bed temperature average value Tave and the target bed temperature Tt by the learning value K and the transition of the catalyst inlet exhaust temperature Tb when the steady deviation is eliminated. (B) is a time chart which shows the change mode of the learning value K at that time. The flowchart which shows the learning value update routine for memorize | storing the learning value K in non-volatile RAM. The time chart which shows transition for every update of the learning value K when temporary abnormality has generate | occur | produced. (A) And (b) is a time chart which shows transition for every update of the learning value K, and transition of the counter value of the counter C. FIG. The flowchart which shows the abnormality diagnosis procedure of this embodiment. (A) And (b) is a time chart which shows transition for every update of the learning value K, and transition of the counter value of the counter C. FIG. (A)-(c) is a time chart which shows the transition for every update of the learning value K, the transition of the counter value of the counter C, and the change aspect of an abnormality flag.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Intake passage, 13 ... Combustion chamber, 14 ... Exhaust passage, 16 ... Air flow meter, 19 ... Intake throttle valve, 25 ... NOx catalytic converter, 26 ... PM filter, 27 ... Oxidation catalytic converter, 28 ... Inlet gas temperature sensor, 29 ... Outlet gas temperature sensor, 30 ... Differential pressure sensor, 31, 32 ... Air-fuel ratio sensor, 33 ... EGR passage, 36 ... EGR valve, 40 ... Injector, 41 ... High pressure fuel supply pipe, 42 ... Common rail , 43 ... Fuel pump, 44 ... Rail pressure sensor, 45 ... Low pressure fuel supply pipe, 46 ... Addition valve, 50 ... Electronic control device (learning value judging means, counting means, abnormality judging means), 51 ... NE sensor, 52 ... Accelerator sensor, 53 ... throttle valve sensor, 54 ... intake air temperature sensor, 55 ... water temperature sensor.

Claims (5)

A temperature increase control is performed to raise the temperature of the catalyst to a target bed temperature by supplying an unburned fuel component to a catalyst provided in an exhaust system, and based on the catalyst bed temperature during the temperature increase control and the target bed temperature In the abnormality diagnosis device for an internal combustion engine that updates the learning value so as to be a value corresponding to the difference between the two, and determines whether there is an abnormality based on the learning value at the time of the update,
Learning value determination means for determining whether or not the learning value is outside the appropriate range every time the learning value is updated;
An abnormality determining means for determining that there is an abnormality when the learning value determining means determines that the value is outside the appropriate range of the learning value, and is continuously performed a plurality of times for each update of the learning value;
An abnormality diagnosis device for an internal combustion engine, comprising: The abnormality diagnosis apparatus for an internal combustion engine according to claim 1, wherein the internal combustion engine is provided with an addition valve for adding fuel upstream of the catalyst in the exhaust system. In the internal combustion engine, a filter for collecting particulates is provided in the exhaust system, and filter regeneration is performed by burning the particulates so that the amount of particulates collected in the filter is less than a predetermined value. 3. The abnormality diagnosis device for an internal combustion engine according to claim 1, wherein when performing, temperature increase control is performed to raise the temperature of the catalyst to a target bed temperature by supplying an unburned fuel component to the catalyst. The abnormality diagnosis device for an internal combustion engine according to claim 3,
When the learning value determining means determines that the learning value is outside the proper range, the count value is counted up. When the learning value is determined to be within the proper range, the count value is counted up. Is provided with a counting means for resetting to “0”,
The abnormality determination means determines that there is an abnormality when the count value is equal to or greater than a determination value set to a value of “2” or more,
The abnormality diagnosis apparatus for an internal combustion engine, wherein the count unit resets the count value to “0” even when the filter regeneration is completed. The abnormality diagnosis device for an internal combustion engine according to claim 3 or 4,
When the learning value determining means determines that the learning value is outside the proper range, the count value is counted up. When the learning value is determined to be within the proper range, the count value is counted up. Is provided with a counting means for resetting to “0”,
The learning value is updated on condition that the catalyst bed temperature is stable at a value equal to or higher than the combustible value of the fine particles,
The abnormality determining means determines that there is an abnormality when the count value by the counting means is equal to or greater than a determination value determined to be “2” or more, and allows an elapsed time from the start point of the filter regeneration. An abnormality diagnosing device for an internal combustion engine, characterized in that, when the filter regeneration is not completed even after a lapse of time, an abnormality is determined regardless of the count value.

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