JP2010121514A - Exhaust emission control system and exhaust emission control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control method and an exhaust emission control system, adjusting an actual injection estimation amount to a target injection amount in an exhaust pipe direct fuel injection with respect to deterioration of a fuel injection valve of an exhaust pipe direct fuel injection device caused by clogging or the like, and prolonging a time to replace a fuel injection valve. <P>SOLUTION: While the exhaust pipe direct fuel injection is performed, when an air excessive ratio error Δλ as a difference between a calculation value λc of an air excess ratio λ on an outlet side of an exhaust emission control device and a measurement value λm exceeds a threshold Δλc set in advance, or a temperature error ΔTd as a difference between a calculation value ΔTc of a temperature difference ΔT between an inlet side and the outlet side of the exhaust emission control device and a measurement value ΔTm exceeds a threshold ΔTc set in advance, a deviation ΔF between an injection estimation value Fr estimated that fuel of the injection estimation amount Fr is actually injected in the exhaust pipe direct fuel injection and a target injection amount Ft is calculated. An injection instruction amount Fc of the exhaust pipe direct fuel injection is corrected based on the calculated deviation ΔF. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification system having an exhaust pipe direct fuel injection device upstream of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine, which is caused by clogging of a fuel injection valve of the exhaust pipe direct fuel injection device. The present invention relates to an exhaust gas purification system and an exhaust gas purification method that can match an actual injection estimated amount in direct exhaust fuel injection in an exhaust pipe with a target injection amount against deterioration.

  When purifying the exhaust gas of an internal combustion engine mounted on a vehicle or the like, an exhaust gas purification device including an oxidation catalyst, a NOx occlusion reduction catalyst, a filter with a catalyst, and the like is provided in the exhaust passage of the internal combustion engine, The exhaust gas that passes through is purified. In an exhaust gas purification system equipped with such an exhaust gas purification device, in the exhaust pipe for directly injecting fuel into the exhaust passage for the purpose of raising the temperature of regeneration of the filter with catalyst or for the rich reduction of the NOx storage reduction catalyst Direct fuel injection is used. In this exhaust pipe direct fuel injection, there is no problem of oil dilution compared to post injection in which fuel is injected into the cylinder, so there is no problem with engine durability due to this oil dilution and post injection. In this way, since a part of the injection adheres to the inner wall of the cylinder, the temperature raising efficiency of the catalyst does not decrease. Therefore, the direct fuel injection in the exhaust pipe has a good fuel efficiency with respect to the temperature rise of the exhaust gas. It has become a method.

  However, the direct fuel injection into the exhaust pipe has a problem that the fuel injection valve is clogged (coking). This clogging is a symptom that fuel such as micro diesel oil leaks from the gap between the fuel injection valve and the injection nozzle during no injection and carbonizes, causing clogging of the fuel injection valve. The injection amount may be significantly reduced during low flow injection. In the direct fuel injection into the exhaust pipe, the target temperature is not reached unless the fuel injection amount reaches the control target amount, or in the case of direct fuel injection to the NOx storage reduction type catalyst, the fuel as the reducing agent is insufficient. As a result, the NOx purification rate decreases.

  In this regard, in an exhaust purification device that includes a fuel addition valve upstream of a DPF (diesel particulate filter) and adds fuel into the exhaust passage during DPF regeneration, an exhaust pressure sensor is provided between the fuel addition valve and the DPF. There has been proposed an exhaust purification device for an internal combustion engine that diagnoses the fuel addition valve based on the detected pressure of the exhaust pressure sensor at the estimated time when the fuel added from the fuel addition valve reaches the DPF (for example, Patent Document 1).

  Further, a reducing agent addition nozzle is provided on the upstream side of the exhaust purification catalyst, and pressure detecting means provided on the downstream side of the passage opening / closing valve of the reducing agent supply passage for supplying the reducing agent to the reducing agent addition nozzle includes a passage opening / closing valve. Based on the pressure detected during the valve opening period and before and after the valve opening period, the second pressure is higher than the first pressure before the passage opening / closing valve is opened, and after the valve is closed, the first pressure is increased. If the pressure of the reducing agent nozzle is poor when the pressure drops below the pressure, and the pressure detected during the valve opening period and before and after the valve opening period is the same, the passage on / off valve is abnormal. If it is higher than the first pressure, it is assumed that the passage on-off valve is open and malfunctioning. If it is lower than the second pressure, the passage on-off valve is closed and malfunctioning. An exhaust gas purification device for an internal combustion engine that is judged to be present has been proposed (for example, patent documents) Reference 1).

  However, in these internal combustion engine exhaust gas purification apparatuses, a failure such as clogging of the fuel addition valve (fuel injection valve) is diagnosed, but the actual injection estimated amount of the fuel is determined based on the degree of clogging. There is no mention of matching the quantity.

  In the direct fuel injection in these exhaust pipes, the target temperature is not reached when the fuel injection amount changes. Therefore, the fuel temperature is adjusted to the target temperature by using the detected value of the exhaust gas temperature sensor on the downstream side of the exhaust gas purification device. When the fuel injection amount is changed or when the fuel injection amount is changed, the reducing agent is insufficient and the NOx purification rate is lowered. Therefore, the excess air ratio sensor (λ sensor) on the downstream side of the exhaust gas purification device It is also conceivable to use the detected value of) to perform a hoodback control that changes the fuel injection instruction amount so that the target excess air ratio is obtained.

However, there is a problem that there is a limit only by correcting the feedback control. For example, an upper and lower limit value is normally set for the correction amount, and no further correction is performed. In addition, since it is a precondition for correction in feedback control that the actual fuel injection amount matches the injection command amount, if the deviation is large, the correction will be more or less than expected and as intended. May not converge to the feedback. Therefore, as a premise of feedback control, it is important to match the actual fuel injection amount with the injection instruction amount.
JP 2008-2309 A JP 2002-129945 A

  The present invention has been made in view of the above situation, and an object thereof is an exhaust gas purification system including an exhaust pipe direct fuel injection device upstream of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine. Until the fuel injection valve is exchanged, the actual injection estimated amount in the direct fuel injection in the exhaust pipe can be matched with the target injection amount against deterioration due to clogging of the fuel injection valve of the direct fuel injection device in the exhaust pipe. It is an object of the present invention to provide an exhaust gas purification method and an exhaust gas purification system capable of extending the period.

  An exhaust gas purification system for achieving the above object includes a direct fuel injection device in an exhaust pipe upstream of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine, and purification or regeneration of the exhaust gas purification device. In the exhaust gas purification system including the control device for the exhaust gas purification device, a first temperature sensor is provided on the inlet side of the exhaust gas purification device, a second temperature sensor and an excess air ratio sensor are provided on the outlet side of the exhaust gas purification device, and While the control device performs direct fuel injection in the exhaust pipe, it calculates an excess air ratio error, which is the difference between the measured value and the calculated excess air ratio at the outlet side of the exhaust gas purification device. When a temperature exceeds a preset threshold value, or a temperature error that is a difference between a calculated value and a measured value of a temperature difference between the inlet side and the outlet side of the exhaust gas purification device is calculated, and the temperature error is calculated in advance. When the determined threshold value is exceeded, a deviation amount between the estimated injection amount estimated to have been actually injected by direct fuel injection in the exhaust pipe and the target injection amount is calculated, and based on the calculated deviation amount, It is configured to correct the injection command amount for direct fuel injection in the exhaust pipe.

  Alternatively, an exhaust gas purification system for achieving the object as described above includes an exhaust pipe direct fuel injection device on the upstream side of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine, and purification of the exhaust gas purification device. Alternatively, in the exhaust gas purification system provided with the control device for regeneration, the first temperature sensor is provided on the inlet side of the exhaust gas purification device, and the second temperature sensor and the excess air ratio sensor are provided on the outlet side of the exhaust gas purification device. The control device calculates an excess air ratio error, which is a difference between the calculated value of the excess air ratio on the outlet side of the exhaust gas purification device and the measured value, while performing direct fuel injection in the exhaust pipe. When the rate error exceeds a preset threshold value, a temperature error that is a difference between a measured value and a calculated value of the temperature difference between the inlet side and the outlet side of the exhaust gas purification device is calculated, and this temperature is calculated. When the difference exceeds a preset threshold, a deviation amount between the estimated injection amount estimated to be actually injected by direct fuel injection in the exhaust pipe and the target injection amount is calculated, and the calculated deviation amount is calculated. Based on this, it is configured to correct the injection command amount of the direct fuel injection in the exhaust pipe.

  This excess air ratio error Δλ is the sum of the intake air amount Am measured by the intake air amount sensor (MAF sensor), the in-cylinder (in-cylinder) fuel injection amount Fi, and the target injection amount Ft of direct fuel injection in the exhaust pipe. It is calculated as the difference Δλ (= λc−λm) between the excess air ratio λc calculated from the fuel injection amount (Fa = Fi + Ft) and the measured value λm of the excess air ratio sensor (λ sensor) after the catalyst.

  The calculated value ΔTc of the temperature difference is the exhaust gas amount and the calorific value obtained from the detected value T1 of the catalyst inlet temperature sensor, the fuel injection instruction value Fc into the exhaust pipe, and the air amount Am detected by the intake air amount sensor. From the difference (T1−To) calculated from the catalyst outlet calculated temperature To. Further, the measured value ΔTm of the temperature difference can be obtained from the difference (T1−T2) between the detection value T1 detected by the catalyst inlet temperature sensor and the detection value T2 detected by the catalyst outlet temperature sensor.

  Further, from the difference Δλ between the calculated value λc of the excess air ratio on the upstream side of the exhaust gas purification device and the measured value λm of the excess air ratio sensor on the downstream side, it is estimated that the fuel was actually injected by direct fuel injection into the exhaust pipe. The difference ΔF (= Fr−Ft) between the estimated injection amount Fr and the target injection amount Ft is calculated as a deviation amount. The deviation amount ΔF is used as a correction amount for the target injection amount Ft, the target injection amount Ft is corrected with the correction amount ΔF, and this correction is performed to set the injection instruction amount Fc corresponding to the target injection amount Ft. Actually, the BPW map (map data of the target injection amount and the valve opening time) is corrected by the deviation amount ΔF, and the corrected injection instruction amount Fc is calculated. Thereby, even if the valve opening time of the fuel injection valve is the same, the estimated injection amount Fr that is the actual injection amount changes depending on the degree of clogging of the injection port of the fuel injection valve. Calculate Fc.

  When the data itself such as map data for calculating the target injection amount Ft is corrected, the deviation amount ΔF is corrected to be small. On the other hand, when the BPW map for calculating the injection instruction amount Fc from the target injection amount Ft is corrected, the deviation amount ΔF remains uncorrected.

  In the exhaust gas purification system, the control device is configured to generate a warning when the deviation amount or the correction amount of the target injection amount deviates from between a preset lower limit value and upper limit value.

  In other words, when the correction amount ΔF becomes excessive, an error is judged and displayed on a failure diagnosis (OBD) system or the like, and a warning is given to a user such as a driver. Encourage exchange. Note that the correction amount ΔF is also reset after the injection valve of the direct fuel injection device in the exhaust pipe is repaired or replaced.

  An exhaust gas purification method for achieving the above object includes a direct fuel injection device in the exhaust pipe upstream of the exhaust gas purification device provided in the exhaust passage of the internal combustion engine, and purification of the exhaust gas purification device. Alternatively, in the exhaust gas purification method of the exhaust gas purification system provided with the control device for regeneration, the first temperature sensor is provided on the inlet side of the exhaust gas purification device, and the second temperature sensor and excess air are provided on the outlet side of the exhaust gas purification device. In the state where a fuel ratio sensor is provided and direct fuel injection is performed in the exhaust pipe, an excess air ratio error, which is the difference between the calculated value of the excess air ratio on the outlet side of the exhaust gas purification device and the measured value, is calculated. When the error exceeds a preset threshold value, or a temperature error that is a difference between a calculated value and a measured value of the temperature difference between the inlet side and the outlet side of the exhaust gas purification device is calculated, the temperature error is calculated in advance. Setting When the calculated threshold value is exceeded, the deviation amount between the estimated injection amount estimated to be actually injected by direct fuel injection in the exhaust pipe and the target injection amount is calculated, and the exhaust amount is calculated based on the calculated deviation amount. This is a method characterized by correcting the injection command amount of direct in-pipe fuel injection.

  Alternatively, an exhaust gas purification method for achieving the above object includes a direct fuel injection device in the exhaust pipe on the upstream side of the exhaust gas purification device provided in the exhaust passage of the internal combustion engine, and purification of the exhaust gas purification device. Alternatively, in the exhaust gas purification method of the exhaust gas purification system provided with the control device for regeneration, the first temperature sensor is provided on the inlet side of the exhaust gas purification device, and the second temperature sensor and excess air are provided on the outlet side of the exhaust gas purification device. In the state where a fuel ratio sensor is provided and direct fuel injection is performed in the exhaust pipe, an excess air ratio error, which is the difference between the calculated value of the excess air ratio on the outlet side of the exhaust gas purification device and the measured value, is calculated. When the error exceeds a preset threshold value, a temperature error that is a difference between the calculated value and the calculated value of the temperature difference between the inlet side and the outlet side of the exhaust gas purification device is calculated. When the determined threshold value is exceeded, a deviation amount between the estimated injection amount estimated to have been actually injected by direct fuel injection in the exhaust pipe and the target injection amount is calculated, and based on the calculated deviation amount, This is a method characterized by correcting the injection command amount of direct fuel injection in the exhaust pipe.

  In the above exhaust gas purification method, a warning is generated when the deviation amount or the correction amount of the target injection amount deviates from between a preset lower limit value and upper limit value.

  According to these exhaust gas purification methods, the same operational effects as those of the exhaust gas purification system described above can be obtained.

  According to the exhaust gas purification method and the exhaust gas purification system of the present invention, in the exhaust gas purification system provided with the direct fuel injection device in the exhaust pipe upstream of the exhaust gas purification device provided in the exhaust passage of the internal combustion engine, The actual injection estimated amount in the direct fuel injection in the exhaust pipe can be matched with the target injection amount against deterioration due to clogging of the fuel injection valve of the direct fuel injection device, and the period until the fuel injection valve is replaced can be increased. Can be extended. In addition, since a correlation between the injection instruction amount and the actual injection estimation amount is always obtained, feedback control of the injection instruction amount with respect to the target control amount can be normally performed.

  Hereinafter, an exhaust gas purification method and an exhaust gas purification system according to embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of an exhaust gas purification system 1 according to an embodiment of the present invention. The exhaust gas purification system 1 includes an exhaust gas purification device 18 in an exhaust passage 16 of an engine (internal combustion engine) 10.

  The engine 10 of the exhaust gas purification system 1 includes an intake air amount sensor 12 (MAF sensor), a compressor 13b of a turbocharger 13, an intercooler 14, and an intake valve (intake throttle) 15 in an intake passage 11 connected to an intake manifold 10a. It has. Further, the exhaust passage 16 connected to the exhaust manifold 10b includes a turbine 13b of the turbocharger 13, a fuel injection device 17 for injecting fuel and the like, and an exhaust gas purification device 18. Further, the EGR passage 19 connecting the exhaust manifold 10b and the intake manifold 10a is provided with an EGR cooler 20 and an EGR valve 21.

  In the exhaust gas purification device 18, in order to maintain the purification performance of the exhaust gas G, it is necessary to raise the temperature of the supported catalyst to a certain temperature equal to or higher than the catalyst activation temperature. In the configuration of FIG. 1, the exhaust gas purifying device 18 includes an oxidation catalyst device (DOC) 18a, a NOx occlusion reduction type catalyst device (LNT) 18b, and a filter device with catalyst (CSF) 18c.

  The oxidation catalyst device 18a is formed by supporting an oxidation catalyst such as platinum on a porous ceramic honeycomb structure support. This oxidation catalyst serves to oxidize HC and CO in the exhaust gas to purify the exhaust gas, and is supplied as a NOx reducing agent during NOx regeneration for restoring the NOx storage capacity of the NOx storage reduction catalyst 3 It functions to oxidize part of the HC and raise the temperature of the exhaust gas.

  The NOx occlusion reduction type catalyst device 18b is formed by supporting an alkali metal or an alkaline earth metal together with a noble metal, and oxidizes NO in exhaust gas containing excess oxygen and adsorbs it as a nitrate on the catalyst to purify NOx. . The NOx occlusion reduction type catalyst stores NOx when the exhaust gas is lean, and releases the stored NOx when the exhaust gas is rich, and reduces the released NOx in a reducing atmosphere to reduce NOx. To reduce.

  The catalyst-equipped filter device 18c is composed of a DPF with a catalyst provided with a diesel particulate filter (DPF) for collecting particulate matter (PM) in the exhaust gas. The catalyst-attached DPF is formed of a monolith honeycomb wall flow type filter or the like in which the inlet and outlet of a porous ceramic honeycomb channel are alternately plugged. A catalyst such as platinum or cerium oxide is supported on the filter.

  By this DPF with catalyst, PM in the exhaust gas is collected by the porous ceramic wall. When the amount of collected PM increases, fuel is injected into the exhaust gas, the fuel is oxidized by an oxidation catalyst to raise the temperature of the exhaust gas, and the DPF with the catalyst is made up by the hot exhaust gas. The PM is increased to the combustion start temperature of PM, and the collected PM is forcibly burned and removed to perform PM regeneration of the DPF with catalyst.

  Further, in order to measure the temperature of the exhaust gas G, a first temperature sensor 22 is provided at the inlet of the exhaust gas purification device 18, and a second temperature sensor 23 and a λ (excess air ratio) sensor 24 are provided at the outlet of the exhaust gas purification device 18. Is disposed.

  A control device (illustrated) that inputs measurement values of these sensors 22, 23, 24, etc. and data necessary for operation control of the engine 10 to perform engine operation state, exhaust gas purification control and regeneration control of the exhaust gas purification system 1 Not). This control device is a control device called an ECU (engine control unit). In the control relating to the exhaust gas purification method of the present invention, the intake valve 15 is based on the data from the engine 10 and the detected value of the intake air amount sensor 12 or the like. The exhaust pipe direct fuel injection device 17, the EGR valve 22 and the like are controlled.

  Next, the exhaust gas purification method of the first embodiment of the present invention will be described with reference to a control flow for correction control for the deterioration of the injection amount of the direct fuel injection in the exhaust pipe of FIG. The control flow of FIG. 2 is repeatedly called by the control flow of the advanced engine when the operation of the engine 10 is started and the control unit (ECU) is in a state in which fuel is directly injected into the exhaust pipe.

  When the control flow of FIG. 2 starts, in step S11, an excess air ratio error Δλ (= λc−λm), which is the difference between the calculated value λc of the excess air ratio on the outlet side of the exhaust gas purification device and the measured value λm, is calculated. To do. This excess air ratio error Δλ is the target injection amount Ft of the intake air amount Am measured by the intake air amount sensor (MAF sensor), the in-cylinder (in-cylinder) fuel injection amount Fi, and the fuel injection amount F of the direct fuel injection in the exhaust pipe. Calculated as the difference (Δλ = λc−λm) between the excess air ratio λc calculated from the total fuel injection amount (Fa = Fi + Ft), which is the sum of the above, and the measured value λm detected by the λ sensor (excess air ratio sensor) 24 Is done.

  In the next step S12, the excess air ratio error Δλ is checked, and it is determined whether or not the absolute value | Δλ | of the excess air ratio error λ is equal to or greater than the correction excess air ratio threshold value Δλc. If the absolute value | Δλ | of the excess air ratio error Δλ is smaller than the correction excess air ratio threshold value Δλc (NO) in step S12, the process goes to step S13. If the absolute value | Δλ | of the excess air ratio error Δλ is greater than or equal to the preset correction excess air ratio threshold value Δλc (YES) in step S12, the process goes to step S15. It is not necessarily an absolute value evaluation, and a lower limit threshold value and an upper limit threshold value are provided, and it may be determined whether the excess air ratio error Δλ is between the lower limit threshold value and the upper limit threshold value (YES) (NO). .

  In step S13, a temperature error ΔTd that is a difference ΔTm between the calculated value ΔTc of the temperature difference ΔT between the inlet side and the outlet side of the exhaust gas purification device 18 and the measured value is calculated. The difference ΔTc between the calculated values of the temperature difference ΔT is obtained by calculating the outlet side temperature To after the temperature rise by direct fuel injection in the exhaust pipe from the target injection amount Ft of the intake air amount Am and the total fuel injection amount F of the direct fuel injection in the exhaust pipe. The amount of heat generated can be calculated, and the exhaust gas amount on the outlet side can be calculated from the intake air amount Am, the in-cylinder fuel injection amount Fi, and the target injection amount Ft of the fuel injection amount F of the direct fuel injection in the exhaust pipe. From the amount of heat generated and the amount of exhaust gas, it is possible to calculate the increase in the temperature of the exhaust gas on the outlet side, that is, the calculated value ΔTc of the temperature difference ΔT between the inlet side and the outlet side. If necessary, the calculated value ΔTc, which is an increase in temperature, is corrected in consideration of the heat capacity of the exhaust gas purification device 18 and the heat transfer amount to the exhaust gas purification device.

  On the other hand, the difference ΔTm in the measured value of the temperature difference ΔT can be calculated by the difference (T1−T2) between the measured value T1 of the first temperature sensor 22 and the measured value T2 of the second temperature sensor 2. Therefore, the temperature error ΔTd can be calculated by ΔTd = ΔTc−ΔTm.

  In other words, the calculated value ΔTc of the temperature difference ΔT includes the detected value T1 of the first temperature sensor 22 at the inlet of the exhaust gas purification device 18, the injection instruction amount Fc, and the intake air amount Am detected by the intake air amount sensor 12. The difference ΔTc = T1-To between the exhaust gas temperature To on the outlet side of the exhaust gas purification device 18 calculated from the exhaust gas amount and the calorific value obtained from the above can be obtained. The measured value ΔTm of the temperature difference ΔT is the difference between the detection value T1 of the first temperature sensor 22 at the inlet of the exhaust gas purification device 18 and the detection value T2 of the second temperature sensor 23 at the outlet of the catalytic exhaust gas purification device 18. It can obtain | require by (DELTA) Tm = T1-T2.

  In the next step S14, the temperature error ΔTd is checked, and it is determined whether or not the absolute value | ΔTd | of the temperature error ΔTd is equal to or greater than the correction temperature error threshold ΔTd1. If it is determined in step S14 that the absolute value | ΔTd | of the temperature error ΔTd is smaller than the correction temperature error threshold ΔTd1 (NO), the process returns to step S11. If the absolute value | ΔTd | of the temperature error ΔTd is greater than or equal to the preset correction temperature error threshold ΔTd1 (YES) in step S14, the process goes to step S15. Note that the lower limit threshold value and the upper limit threshold value are not necessarily evaluated, and it may be determined whether the temperature error ΔTd is not between the lower limit threshold value and the upper limit threshold value (YES) (NO).

  In step S15, a deviation amount ΔF between the estimated injection amount Fr estimated to be actually injected by direct fuel injection in the exhaust pipe and the target injection amount Ft is calculated. This actual injection estimation amount Fr is calculated by calculating the relationship between the total fuel injection amount (Fa = Fi + Fr), which is the sum of the in-cylinder fuel injection amount Fi and the fuel injection amount F of the direct fuel injection in the exhaust pipe, and the excess air ratio λ. Use.

  Since the theoretical air amount Aa is proportional to the total fuel injection amount Fa (Aa = Ka × Fa), the theoretical air amount Aa with respect to the total fuel injection amount Fa can be calculated. Since the ratio [(Ai / Fa) / (Aa / Fa)] between the air / fuel ratio (Ai / Fa) and the stoichiometric air / fuel ratio (Aa / Fa), which is the ratio of the amount Fa and the supply air amount Ai, λ = Ai / Aa = Ai / (Ka × Fa). Therefore, Fa = Ai / (Ka × λa). Based on this equation, the actual estimated injection amount Fr in the direct fuel injection in the exhaust pipe is calculated based on the intake air amount Am detected by the intake air amount sensor 12, the measured value λm of the excess air ratio λ detected by the λ sensor 24, and the in-cylinder From the fuel injection amount Fi, it is calculated as Fr = Ai / (Ka × λm) −Fi. The in-cylinder fuel injection amount Fi is determined by the operating state of the engine 10 (for example, engine speed, load, etc.) and the exhaust gas purification method (for example, purification control, regeneration control, etc.). A known or well-known technique is used to determine the in-cylinder fuel injection amount Fi.

  On the other hand, the target injection amount Ft is determined by control for purification of exhaust gas in the exhaust gas purification device 18 and regeneration for the exhaust gas purification device 18. A known or publicly known technique can be used to determine the target injection amount Ft in the control for purification or the control for regeneration. The deviation amount ΔF is calculated from the estimated injection amount Fr estimated to be actually injected by the direct fuel injection in the exhaust pipe calculated above and the target injection amount Ft.

  In the next step S16, the injection instruction amount Fc for direct fuel injection in the exhaust pipe is corrected based on the calculated deviation amount ΔF. That is, the deviation amount ΔF is used as the correction amount ΔFt of the target injection amount Ft, and the target injection amount Ft is corrected by this correction amount ΔFt (Ft = Ft + ΔFt) to obtain the injection amount instruction amount Fc. The correction of the injection instruction amount Fc corrects data itself such as map data for calculating the target injection amount Ft. Alternatively, the BPW map (map data of target injection amount and valve opening time) for calculating the injection instruction amount Fc from the target injection amount Ft is corrected. That is, without correcting the target injection amount Ft, the valve opening time (driving time) of the exhaust pipe direct fuel injection device 17 with respect to the target injection amount Ft is corrected. For this correction, it is not necessary to correct the value of the slip amount ΔF. For example, the correction is performed to about 1/100 of the shift amount ΔF. After these corrections, the injection instruction amount Fc for direct fuel injection in the exhaust pipe is calculated using the corrected target injection amount data and BPW map data. That is, integration correction is performed in which a correction amount about 1/100 of the deviation amount ΔF is sequentially integrated.

  In the next step S17, it is determined whether or not the deviation amount ΔF is between the warning injection amount deviation lower limit threshold ΔFcd and the warning injection amount deviation upper limit threshold ΔFcu. When the deviation amount ΔF is between the warning injection amount deviation lower limit threshold value ΔFcd and the warning injection amount deviation upper limit threshold value ΔFcu (YES), a return is made, and this deviation amount ΔF is the warning injection amount deviation amount. If it is not between the lower limit threshold ΔFcd and the warning injection amount deviation upper limit threshold ΔFcu (NO), the process goes to step S18.

  In step S18, since the deviation amount ΔF is not between the warning injection amount deviation lower limit threshold ΔFcd and the warning injection amount deviation upper limit threshold ΔFcu, an error determination output is displayed on the fault diagnosis (OBD: On-Board Diagnostics) system. In such a case, a user such as a driver is warned to prompt replacement of the direct fuel injection device 17 in the exhaust pipe. That is, when the deviation amount becomes excessive, an error is determined and output to the failure diagnosis system, and a warning is given to a user such as a driver to prompt repair or replacement of the failure of the direct fuel injection device 17 in the exhaust pipe. After this step S18, the process returns. After repairing or replacing the injection valve of the direct fuel injection device in the exhaust pipe, the correction amount of the target injection amount Ft or the injection instruction amount Fc is also reset.

  Note that when the data itself such as map data for calculating the target injection amount Ft is corrected in step S16, the shift amount ΔF is corrected to be small. Therefore, the determination in step S17 determines that the shift amount is the previous time. A warning is issued when the correction is over and the warning injection amount deviation threshold ΔFc is exceeded. On the other hand, when the BPW map (map data of the target injection amount and the valve opening time) for calculating the injection instruction amount Fc from the target injection amount Ft is corrected in step S16, the deviation amount ΔF remains uncorrected. The determination in S17 gives a warning when the amount of deviation becomes equal to or greater than the warning injection amount deviation amount threshold value ΔFc when the exhaust pipe direct fuel injection device 17 is repaired or replaced or when it is new.

  When the control flow of FIG. 2 returns to the state where direct fuel injection in the exhaust pipe is performed again, it is called by the control flow of the advanced engine and is repeatedly executed until the operation of the engine 10 is stopped. Is done.

  The following control can be performed by the control of the exhaust gas purification method of the first embodiment by the control device (ECU) of the exhaust gas purification system 1 described above.

  While performing direct fuel injection in the exhaust pipe, an excess air ratio error Δλ, which is the difference between the calculated value λc of the excess air ratio λ on the outlet side of the exhaust gas purification device 18 and the measured value λm, is calculated. When the error Δλ exceeds a preset threshold value Δλc, or the temperature error ΔTd, which is the difference between the calculated value ΔTc of the temperature difference ΔT between the inlet side and the outlet side of the exhaust gas purification device 18 and the measured value ΔTm, is calculated. When the temperature error ΔTd exceeds a preset threshold value ΔTc, a deviation amount ΔF between the estimated injection amount Fr estimated to be actually injected by direct fuel injection in the exhaust pipe and the target injection amount Ft is calculated. The injection instruction amount Fc for direct fuel injection in the exhaust pipe can be corrected based on the calculated deviation amount ΔF.

  Next, an exhaust gas purification method according to a second embodiment of the present invention will be described with reference to a control flow for correction control for the deterioration of the injection amount of direct fuel injection in the exhaust pipe in FIG. The control flow of FIG. 3 checks the excess air ratio error Δλ in the determination of step S12, and if the absolute value | Δλ | of the excess air ratio error Δλ is equal to or larger than the correction excess air ratio threshold Δλc (YES) ) Go to step S13 instead of step S15. Otherwise (NO), go to step S11 instead of step S13. The other configuration is the same as the control flow of FIG.

  The following control can be performed by controlling the exhaust gas purification method of the second embodiment by the control device (ECU) of the exhaust gas purification system 1 described above.

  While performing direct fuel injection in the exhaust pipe, an excess air ratio error Δλ, which is the difference between the calculated value λc of the excess air ratio λ on the outlet side of the exhaust gas purification device 18 and the measured value λm, is calculated. When the error Δλ exceeds a preset threshold value Δλc, a temperature error ΔTd, which is the difference between the calculated value ΔTc of the temperature difference ΔT between the inlet side and the outlet side of the exhaust gas purification device 18 and the measured value ΔTm, is calculated. When the temperature error ΔTd exceeds a preset threshold value ΔTc, a deviation amount ΔF between the estimated injection amount Fr estimated to be actually injected by direct fuel injection in the exhaust pipe and the target injection amount Ft is calculated. The injection instruction amount Fc for direct fuel injection in the exhaust pipe can be corrected based on the calculated deviation amount ΔF.

  Therefore, according to the exhaust gas purification system 1 and the exhaust gas purification method described above, the exhaust gas purification system including the exhaust pipe direct fuel injection device 17 on the upstream side of the exhaust gas purification device 18 provided in the exhaust passage 16 of the engine 10. 1, the actual injection estimated amount Fr in the direct fuel injection in the exhaust pipe can be matched with the target injection amount Ft against the deterioration due to clogging of the fuel injection valve of the direct fuel injection device 17 in the exhaust pipe. The period until the fuel injection valve of the direct fuel injection device 17 is replaced can be extended. Further, since the correlation between the injection instruction amount Fc and the actual injection estimation amount Fr is always obtained, the feedback control of the injection instruction amount Fc with respect to the target control amount Ft can be normally performed.

It is a figure which shows the structure of the exhaust gas purification system of embodiment which concerns on this invention. It is a figure which shows the control flow of 1st Embodiment for correction | amendment control with respect to deterioration of the injection quantity of direct fuel injection in an exhaust pipe. It is a figure which shows the control flow of 2nd Embodiment for correction | amendment control with respect to deterioration of the injection quantity of direct fuel injection in an exhaust pipe.

Explanation of symbols

1 Exhaust gas purification system 10 Engine (internal combustion engine)
11 Intake passage 12 Intake intake air amount sensor (MAF sensor)
16 Exhaust passage 17 Direct fuel injection device in exhaust pipe 18 Exhaust gas purification device 22 First temperature sensor 23 Second temperature sensor 24 λ (excess air ratio) sensor

Claims (4)

In an exhaust gas purification system comprising an exhaust pipe fuel direct injection device upstream of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine and a control device for purification or regeneration of the exhaust gas purification device,
A first temperature sensor is provided on the inlet side of the exhaust gas purification device, a second temperature sensor and an excess air ratio sensor are provided on the outlet side of the exhaust gas purification device, and
The control device is
While direct fuel injection in the exhaust pipe is being performed, an excess air ratio error that is the difference between the calculated value and the excess air ratio at the outlet side of the exhaust gas purification device is calculated, and this excess air ratio error is preset. When the threshold is exceeded,
Alternatively, when a temperature error that is a difference between a measured value and a calculated value of the temperature difference between the inlet side and the outlet side of the exhaust gas purification device is calculated, and when the temperature error exceeds a preset threshold value,
The deviation amount between the estimated injection amount estimated to be actually injected by the direct fuel injection in the exhaust pipe and the target injection amount is calculated, and the injection instruction amount of the direct injection in the exhaust pipe is calculated based on the calculated deviation amount. An exhaust gas purification system characterized by correcting. In an exhaust gas purification system comprising an exhaust pipe fuel direct injection device upstream of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine and a control device for purification or regeneration of the exhaust gas purification device,
A first temperature sensor is provided on the inlet side of the exhaust gas purification device, a second temperature sensor and an excess air ratio sensor are provided on the outlet side of the exhaust gas purification device, and
The control device is
With direct fuel injection in the exhaust pipe,
When calculating the excess air ratio error, which is the difference between the calculated value and the excess air ratio at the outlet side of the exhaust gas purification device, and when this excess air ratio error exceeds a preset threshold,
And when calculating the temperature error which is the difference between the calculated value and the measured value of the temperature difference between the inlet side and the outlet side of the exhaust gas purification device, when this temperature error exceeds a preset threshold,
The deviation amount between the estimated injection amount estimated to be actually injected by the direct fuel injection in the exhaust pipe and the target injection amount is calculated, and the injection instruction amount of the direct injection in the exhaust pipe is calculated based on the calculated deviation amount. An exhaust gas purification system characterized by correcting. Exhaust gas purification of an exhaust gas purification system having an exhaust pipe fuel direct injection device upstream of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine and a control device for purification or regeneration of the exhaust gas purification device In the method
A first temperature sensor is provided on the inlet side of the exhaust gas purification device, a second temperature sensor and an excess air ratio sensor are provided on the outlet side of the exhaust gas purification device,
With direct fuel injection in the exhaust pipe,
When calculating the excess air ratio error which is the difference between the calculated value and the excess air ratio at the outlet side of the exhaust gas purification device, and when this excess air ratio error exceeds a preset threshold,
Alternatively, when a temperature error that is a difference between a measured value and a calculated value of the temperature difference between the inlet side and the outlet side of the exhaust gas purification device is calculated, and when the temperature error exceeds a preset threshold value,
The deviation amount between the estimated injection amount estimated to be actually injected by the direct fuel injection in the exhaust pipe and the target injection amount is calculated, and the injection instruction amount of the direct injection in the exhaust pipe is calculated based on the calculated deviation amount. An exhaust gas purification method comprising correcting the exhaust gas. Exhaust gas purification of an exhaust gas purification system having an exhaust pipe fuel direct injection device upstream of an exhaust gas purification device provided in an exhaust passage of an internal combustion engine and a control device for purification or regeneration of the exhaust gas purification device In the method
A first temperature sensor is provided on the inlet side of the exhaust gas purification device, a second temperature sensor and an excess air ratio sensor are provided on the outlet side of the exhaust gas purification device,
With direct fuel injection in the exhaust pipe,
When calculating the excess air ratio error, which is the difference between the calculated value and the excess air ratio at the outlet side of the exhaust gas purification device, and when this excess air ratio error exceeds a preset threshold,
And when calculating the temperature error which is the difference between the calculated value and the measured value of the temperature difference between the inlet side and the outlet side of the exhaust gas purification device, when this temperature error exceeds a preset threshold,
The deviation amount between the estimated injection amount estimated to be actually injected by the direct fuel injection in the exhaust pipe and the target injection amount is calculated, and the injection instruction amount of the direct injection in the exhaust pipe is calculated based on the calculated deviation amount. An exhaust gas purification method comprising correcting the exhaust gas.

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