JP2009002192A - Exhaust gas purification device for internal combustion engine - Google Patents

Abstract

An exhaust purification device for an internal combustion engine suitable for suppressing an excessive increase in filter temperature is provided.
An exhaust emission control device for an internal combustion engine that reacts HC supplied by an HC supply means with a pre-catalyst 20 to remove particulate matter trapped by a particulate filter 21 and regenerate the filter 21. When the deterioration state of the front catalyst 20 is determined by the state determination means (steps S3 and S4), and the deterioration of the front catalyst 20 is determined, the particulate filter is controlled by the HC supply means by the control unit 26 as the control means. The amount of HC supplied during regeneration is reduced so that the amount of HC passing through the deteriorated pre-stage catalyst 20 and flowing into the particulate filter 21 is less than or equal to the amount of HC allowed by the particulate filter 21. did.
[Selection] Figure 2

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine including a pre-stage catalyst such as an oxidation catalyst and a particulate filter, and more particularly to an exhaust gas purification apparatus for an internal combustion engine suitable for suppressing an excessive increase in filter temperature. .

  Conventionally, in order to remove particulate matter (hereinafter referred to as “PM”) typified by soot, which is particulate matter contained in the exhaust of a diesel engine, a pre-stage catalyst such as an oxidation catalyst and its A particulate filter (hereinafter simply referred to as “filter” or “DPF”) that captures PM is provided downstream, and the exhaust gas temperature is raised to, for example, 600 ° C. or higher by the supplied HC using the upstream catalyst. There is known a particulate filter regeneration control device for regenerating a filter by burning and removing PM accumulated on the filter (see Patent Document 1).

This is to quickly raise the temperature to the target temperature during DPF regeneration and maintain the DPF temperature in the vicinity of the target temperature to prevent deterioration of fuel consumption due to unburned PM, damage to the DPF due to high temperature, deterioration of the oxidation catalyst, and the like When performing the temperature raising operation such as post injection and burning and removing the PM accumulated in the DPF, by changing the time ratio (Duty ratio) of the execution / stop of the temperature raising operation according to the temperature of the DPF, The amount of HC supplied to the DOC is controlled in multiple steps or continuously, and the temperature of the DPF is controlled near the target temperature.
JP 2004-301013 A

  By the way, as in the above conventional example, by supplying HC from the upstream during DPF regeneration, the exhaust gas is heated to the target temperature by the oxidation catalyst supported on the preceding catalyst, and the PM collected in the DPF is burned and removed. In the exhaust purification system, the oxidation capacity of the oxidation catalyst carried on the front catalyst decreases as its oxidation capacity decreases, and more HC flows downstream without reacting with the front catalyst, and the DPF is raised to the target temperature. This also increases the amount of HC that is required to achieve this.

  Thus, when the oxidation catalyst deteriorates, HC flowing downstream without reacting reacts with DPF, but the temperature inside the DPF cannot be directly detected, so the amount of exhaust gas decreases during DPF regeneration. When the operation state is changed to, for example, a rapid deceleration operation state, the amount of heat released from the DPF is rapidly decreased, and the temperature of the DPF may be rapidly increased.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide an internal combustion engine exhaust gas purification device suitable for suppressing an excessive increase in filter temperature during regeneration.

  The present invention relates to a pre-stage catalyst having an oxidizing ability provided in an exhaust passage of an internal combustion engine, a particulate filter provided downstream of the pre-stage catalyst and carrying a catalyst for capturing particulate matter in the exhaust, and the pre-stage catalyst. HC supply means for supplying HC from the upstream of the HC, and reacting the HC supplied by the HC supply means with the pre-catalyst to remove particulate matter trapped in the particulate filter and regenerate the filter. An exhaust gas purification apparatus for an internal combustion engine that performs a deterioration state determination of the preceding catalyst by a deterioration state determining means, and when the deterioration of the preceding catalyst is determined, a particulate filter is being regenerated by the control means by the HC supply means The amount of HC passing through the deteriorated front catalyst and flowing into the particulate filter is reduced by reducing the amount of HC supplied to Allowed by tee filter was set as the amount of HC or less.

  Therefore, in the present invention, the deterioration state of the preceding catalyst is determined by the deterioration state determining means, and when the deterioration of the preceding catalyst is determined, the HC supplied during particulate filter regeneration by the HC supplying means by the control means. By reducing the supply amount, the amount of HC passing through the deteriorated pre-stage catalyst and flowing into the particulate filter is less than or equal to the amount of HC allowed by the particulate filter, thereby increasing the temperature of the particulate filter during regeneration. Increase can be suppressed.

  Hereinafter, an exhaust emission control device for an internal combustion engine of the present invention will be described based on each embodiment.

(First embodiment)
FIG. 1 is a system configuration diagram of a supercharged diesel engine showing a first embodiment of an exhaust gas purification apparatus for an internal combustion engine to which the present invention is applied.

  As shown in FIG. 1, the engine body 1 is provided with a common rail fuel injection system including a common rail 2, a fuel injection valve 3, and a supply pump 4, and supplies high-pressure fuel to the engine body 1. The fuel injection valve 3 directly injects fuel into the combustion chamber 5 and can perform pilot injection before main injection, and variably controls the fuel injection pressure by changing the set fuel pressure in the common rail 2. it can.

  An exhaust turbine 10 </ b> A of the supercharger 10 is disposed in the exhaust passage 11, rotates by exhaust from the engine body 1, and drives a compressor 10 </ b> B of the supercharger 10 disposed in the intake passage 12. The compressor 10B of the supercharger 10 is driven by the exhaust turbine 10A to supply compressed air to the engine body 1. The turbocharger 10 of the present embodiment adopts a variable displacement type, and in the low speed range, the variable nozzle (vane) 10C provided on the side of the turbine 10A is narrowed to increase the turbine efficiency. By increasing the turbine capacity by opening the nozzle 10C, a high supercharging effect is obtained in a wide operation region.

  In the intake passage 12, an air flow meter 13 and an air cleaner 14 are disposed on the upstream side of the compressor 10B of the supercharger 10, and an intercooler 15 and a throttle valve 16 are interposed on the downstream side, respectively. The throttle valve 16 is, for example, an electronic control type that can be changed in opening degree using a step motor, and controls the amount of intake air that is drawn into the engine body 1 in accordance with the opening degree.

  The exhaust passage 11 is provided with an EGR passage 6 that branches from between the engine body 1 and the exhaust turbine 10 </ b> A and connects to the intake passage 12, and an EGR valve 7 is interposed in the EGR passage 6. The EGR valve 7 is, for example, an electronically controlled type using a step motor, and controls the amount of exhaust gas recirculated to the intake side according to the opening, that is, the EGR amount sucked into the engine body 1. . In the exhaust passage 11, a pre-stage catalyst 20 and a particulate filter (hereinafter referred to as “DPF” or simply “filter”) 21 are sequentially provided downstream of the exhaust turbine 10 </ b> A. The pre-stage catalyst 20 is composed of an oxidation catalyst (DOC) that oxidizes HC and CO in an active state, or a NOx catalyst. The DPF 21 collects PM (particulate matter) in the exhaust gas. The collected PM is combusted by regeneration control that raises the exhaust temperature.

  As sensors for detecting various states, the air flow meter 13 for detecting the intake air amount, a rotational speed sensor 17 for detecting the engine rotational speed, an accelerator opening sensor 18 for detecting the accelerator opening, and a water temperature sensor 19 for detecting the cooling water temperature. A rail pressure sensor (not shown) for detecting the fuel pressure (that is, fuel injection pressure) in the common rail 2 is provided. Further, temperature sensors 22 and 23 for detecting the exhaust gas temperature at the outlet of the preceding catalyst 20 and the outlet exhaust temperature of the DPF 21 are provided, and a differential pressure sensor 24 for detecting the pressure difference between the inlet and the outlet of the DPF 21 is provided. ing. An exhaust sensor 25 that detects the exhaust air-fuel ratio or the oxygen concentration is provided on the downstream side of the DPF 21 in the exhaust passage 11.

  A control unit 26 constituted by a microcomputer comprising a CPU and its peripheral devices controls the driving of the fuel injection valve 3 by setting the fuel injection amount and the injection timing based on detection signals from the various sensors. The opening control of the throttle valve 16 and the EGR valve 7 is performed.

  The control unit 26 estimates the amount of PM accumulated in the DPF 21 based on a signal from the differential pressure sensor 24 that detects the pressure difference between the inlet and the outlet of the DPF 21, and a predetermined amount of PM is accumulated. If it is determined that the DPF 21 has been reproduced, the regeneration process of the DPF 21 is executed.

  In the regeneration process of the DPF 21, for example, hydrocarbon (HC), carbon monoxide (CO), etc. are supplied from the upstream side of the front catalyst 20, and at this time, exhaust gas whose temperature has been increased by heat generated in the front catalyst 20 is filtered. 21. As a method of supplying HC to the pre-stage catalyst 20, post-injection in which fuel is injected again during the expansion stroke or exhaust stroke after the main injection from the fuel injection valve 3 in the engine body 1 or downstream of the supercharger 10. An injector 27 for injecting fuel (HC) can be exemplified. The fuel (HC) injected by the post injection is discharged from the combustion chamber 5 without being burned depending on the injection timing. The discharged HC is reformed by the high-temperature combustion gas by the main injection, and the front catalyst 20 It will be in the state which is easy to react with. Similarly, the fuel (HC) injected from the injector 27 is also evaporated by the heat of the exhaust gas, and is easily reacted by the pre-stage catalyst 20.

  Further, during regeneration of the DPF 21, the control unit 26 is based on the exhaust gas temperature signal from the temperature sensor 22 disposed at the outlet of the front catalyst 20 and the post injection amount (or the fuel injection amount from the injector 27). The amount of HC reacting with the catalyst 20 and the amount of HC passing through the pre-stage catalyst 20 are estimated, and the deterioration state of the pre-stage catalyst 20 is determined. When the pre-catalyst 20 is deteriorated and the HC oxidizing ability is reduced, the HC reacting with the pre-catalyst 20 is reduced, the temperature rise on the upstream side of the filter 21 is slowed, and PM is burned (oxidized) in the DPF 21. It becomes difficult. Specifically, the outlet exhaust gas temperature of the pre-catalyst 20 is not increased beyond the lower limit value of the set temperature increase rate set by a map or the like with respect to the post injection amount (or the fuel injection amount from the injector 27). In this case, it is determined that the pre-stage catalyst 20 has deteriorated. When the deterioration of the pre-stage catalyst 20 is determined, a warning is issued to the user to prompt the user to replace the pre-stage catalyst 20, and the amount of HC that passes through the pre-stage catalyst 20 can be reacted by the DPF 21 (DPF The post-injection amount or the fuel injection amount by the injector 27 is decreased until the allowable value) is reached.

  FIG. 2 is a flowchart of the reproduction control based on the first embodiment. This regeneration control flowchart is based on a case where it is determined that the pressure difference between the inlet and the outlet of the DPF 21 reaches a predetermined value based on a signal from the differential pressure sensor 24 and a predetermined amount of PM has accumulated. During the regeneration process of the DPF 21 to be executed, the control unit 26 executes the process every predetermined time. In the regeneration process of the DPF 21, post-injection (or fuel injection by the injector 27) for injecting fuel again is executed during the expansion stroke after the main injection from the fuel injection valve 3 in the engine body 1. It is assumed.

  First, in step S1, the control unit 26 reads the pre-stage catalyst deterioration flag, the post injection amount, the exhaust gas temperature after the pre-stage catalyst 20, and the pressure difference before and after the DPF 21, and proceeds to step S2.

  In step S2, it is determined whether or not the pre-stage catalyst deterioration flag F is 0. If the pre-stage catalyst deterioration flag F is (F = 1), the process proceeds to step S5, which is a process after deterioration of the pre-stage catalyst 20. When the pre-stage catalyst deterioration flag F is (F = 0), it is determined that the deterioration of the pre-stage catalyst 20 has not reached the determination standard, and the process proceeds to step S3.

  In step S3, depending on whether the actual temperature increase rate after the pre-catalyst 20 is the catalyst deterioration determination temperature, the pre-catalyst 20 reacts based on the exhaust gas temperature signal and the post-injection amount (or the fuel injection amount by the injector 27). The amount of HC present and the amount of HC passing through the front catalyst 20 are estimated, and the deterioration state of the front catalyst 20 is determined. In this determination, if the actual temperature after the pre-stage catalyst 20 is less than the deterioration determination temperature corresponding to the post injection amount or the fuel injection amount by the injector 27, the deterioration of the pre-stage catalyst 20 has progressed more than a predetermined amount, and the process proceeds to step S4. In step S5, the pre-stage catalyst deterioration flag (F = 1) is set, and the process proceeds to step S5. When the actual temperature after the pre-stage catalyst 20 is sufficiently high and the pre-stage catalyst 20 has not deteriorated, the current processing step is terminated.

  In step S5, since the deterioration of the pre-stage catalyst 20 has progressed, the post-injection amount (or the fuel injection amount by the injector 27) is reduced, and the process proceeds to step S6.

  In step S6, it is determined whether or not the amount of HC passing through the front catalyst 20 is below the allowable value of the DPF 21, and if not, the process returns to step S5 and the post injection amount (or the fuel injection amount by the injector 27). In step S6, it is determined again whether or not the amount of HC passing through the front catalyst 20 is below the allowable value of the DPF 21. By repeating this processing step, when it is determined that the amount of HC passing through the front catalyst 20 has fallen below the allowable value of the DPF 21, the current processing step is terminated. In this way, by limiting the amount of HC supplied to the DPF 21, the DPF 21 is not affected even under conditions where the bed temperature of the DPF 21 during regeneration is maximized.

  The time chart shown in FIG. 3 shows each temporal change state of the temperature of the pre-catalyst 20 and the temperature of the DPF 21 and the PM accumulation amount at the time of DPF regeneration when the post injection or the fuel injection by the injector 27 is started at the time t1. It is.

  In a state where the pre-stage catalyst 20 is not deteriorated, as shown by the solid line in the figure, when the post-injection or fuel injection by the injector 27 is started at time t1 (see B), first, the pre-stage catalyst 20 is in the exhaust gas. The temperature of the front catalyst 20 is increased by the combustion (oxidation) of the HC contained in the catalyst (see A), and the exhaust gas that has passed through the front catalyst 20 and the temperature is increased flows, so that the temperature of the DPF 21 is also increased. It is raised in conjunction (see C). The HC that has passed through the upstream catalyst 20 without being used for the oxidation reaction flows into the DPF 21 and is oxidized by the DPF 21 to raise the temperature of the DPF 21. The temperatures of the front catalyst 20 and the DPF 21 are fed back by a temperature sensor 22 that detects the exhaust gas temperature after passing through the front catalyst 20 and a temperature sensor 23 that detects the exhaust gas temperature after passing through the DPF 21, respectively.

  At the time t2, when the pre-stage catalyst 20 reaches the activation temperature and the exhaust gas temperature passing through the oxidation reaction by the pre-stage catalyst 20 is increased and the temperature of the DPF 21 reaches the target temperature necessary for PM combustion, it accumulates on the DPF 21. Combustion of the PM that has been started is started, and the amount of accumulated PM begins to decrease (see D). The decrease in the PM accumulation amount is fed back by a signal from a differential pressure sensor 24 that detects a pressure difference between the inlet and the outlet of the DPF 21. Thus, in the state where the pre-stage catalyst 20 is not deteriorated, the supplied HC is efficiently consumed for the rise of the exhaust gas temperature, and the regeneration of the DPF 21 is surely executed.

  When the pre-catalyst 20 starts to deteriorate, the HC oxidation reaction by the pre-catalyst 20 gradually decreases, the exhaust gas temperature after passing through the pre-catalyst 20 begins to decrease, and the DPF 21 inlet HC concentration starts to increase. The exhaust gas temperature after passing through the pre-stage catalyst 20 is decreased until catalyst deterioration is determined. The broken lines in FIG. 3 indicate the temporal change states of the temperature of the front-stage catalyst 20 and the temperature of the DPF 21 and the PM deposition amount at the time of regeneration of the DPF 21 when it is determined that the front-stage catalyst 20 has deteriorated.

  In the deteriorated pre-stage catalyst 20, the temperature rise is delayed, for example, at the stage of time t3, the catalyst activation temperature is reached, and the oxidation reaction of HC contained in the exhaust gas becomes active with a delay. . Therefore, the temperature rise of the DPF 21 is also delayed until time t3, and the accumulated PM combustion is also gradually started from time t3. The HC contained in the exhaust gas that passes through the pre-stage catalyst 20 before the pre-stage catalyst 20 is activated flows into the DPF 21 without being oxidized because the oxidation ability of the pre-stage catalyst 20 is reduced. As a result, the amount to be reacted increases and reacts in the DPF 21. Therefore, in this case, there is a possibility that the HC oxidation reaction in the DPF 21 and the PM combustion overlap, and the temperature rise of the DPF 21 becomes excessively large.

  The case where the temperature rise of the DPF 21 becomes excessively large means that the brake pedal is depressed from an operating state where the amount of exhaust gas passing through the DPF 21 is greatly reduced, for example, a traveling state where the vehicle speed is 30 to 40 [km / h]. In the decelerating operation state or the operation state in which the depression of the accelerator pedal is turned off, the flow rate of the exhaust gas passing through the DPF 21 having a function of cooling the DPF 21 on the other side is greatly reduced (refer to the chain line E). In such a case, the accumulated PM is rapidly burned (see the chain line D), and the temperature of the DPF 21 is shown by the chain line (C). There is a risk of abnormally rising.

  However, in the present embodiment, as described above, the post-injection amount or the fuel injection amount by the injector 27 is reduced until the amount of HC passing through the front-stage catalyst 20 reaches the DPF 21 allowable value (decreases as the deterioration of the front-stage catalyst 20 progresses. Accordingly, the DPF 21 inlet HC concentration is maintained at a predetermined concentration. Therefore, it can suppress that the temperature of DPF21 rises too much.

  In the present embodiment, the following effects can be achieved.

  (A) a pre-stage catalyst 20 having an oxidizing ability provided in the exhaust passage 11 of the internal combustion engine, and a particulate filter 21 carrying a catalyst provided downstream of the pre-stage catalyst 20 and capturing particulate matter in the exhaust; Post-injection as HC supply means for supplying HC from upstream of the upstream catalyst 20, or fuel injection means by the injector 27, and reacting the HC supplied by the HC supply means with the upstream catalyst 20, and the particulates. An exhaust gas purification apparatus for an internal combustion engine that removes particulate matter captured by the filter 21 and regenerates the filter 21, and determines the deterioration state of the pre-stage catalyst 20 by deterioration state determination means (steps S3 and S4). When the deterioration of the pre-stage catalyst 20 is determined, the HC supply is performed by the control unit 26 as a control means. The amount of HC supplied during regeneration of the particulate filter 21 is reduced by the stage, and the amount of HC passing through the deteriorated pre-stage catalyst 20 and flowing into the particulate filter 21 is allowed by the particulate filter 21. The following was set. For this reason, an excessive increase in the temperature of the particulate filter 21 during regeneration can be suppressed.

(Second Embodiment)
FIG. 4 is a control flowchart by the controller showing a second embodiment of the exhaust purification system to which the present invention is applied. In the present embodiment, a configuration for correcting the decrease in the target inlet exhaust temperature of the DPF after detecting the deterioration of the pre-stage catalyst is added to the first embodiment. In addition, the same code | symbol is attached | subjected to the same apparatus, member, etc. as 1st Embodiment, and the description is abbreviate | omitted or simplified.

  In FIG. 4, the exhaust purification device for the internal combustion engine of the present embodiment is executed next after the post-injection amount reduction processing of the post injection amount or the fuel injection amount by the injector 27 in step S6 in the control flowchart of the first embodiment. In this processing step, processing steps S7 to S9 for lowering the target inlet exhaust temperature of the DPF 21 are added. Other configurations are the same as those in the first embodiment.

  In step S7, it is determined whether or not the deterioration flag F of the front catalyst 20 has been changed from F = 0 to F = 1, and the deterioration flag F of the front catalyst 20 has been changed in the previous processing step. In this case, the process proceeds to step S8. In step S8, the target inlet exhaust temperature of the DPF 21 is corrected to decrease, and the current process ends. Further, if the deterioration flag F of the pre-stage catalyst 20 is not changed in the previous processing step, that is, if it is changed in the previous processing step, the process proceeds to step S9, and in step S9, the inlet exhaust of the DPF 21 The post injection amount or the fuel injection amount by the injector 27 is controlled so that the temperature becomes the corrected target temperature. The correction amount in this case is the exhaust gas temperature obtained downstream of the front catalyst 20 when the amount of HC passing through the front catalyst 20 executed in steps S5 and S6 is reduced to fall within the allowable range of the DPF 21. Set as standard. The exhaust gas temperature is a map based on the rate of increase in exhaust gas temperature obtained by measuring the change in the HC reaction amount at the pre-catalyst 20 that decreases in advance as the deterioration of the pre-catalyst 20 progresses. Set by etc. Therefore, this correction amount is changed so that the amount of HC passing through the front catalyst 20 increases as the deterioration of the front catalyst 20 progresses, so that it is reduced to the DPF 21 allowable value.

  In this embodiment, when it is determined in step S3 that the pre-stage catalyst 20 has deteriorated beyond a predetermined level, first, in steps S4 to S6, the fuel injection amount by the post injection or the injector 27 is reduced to the HC inflow amount allowed by the DPF 21. Thus, the temperature rise of the DPF 21 is suppressed. In step S8, the target inlet exhaust gas temperature of the DPF 21 is corrected to decrease, and the current process is terminated. In the subsequent processing steps, the process proceeds from step S2 to steps S7 and S9, and the exhaust gas outlet temperature of the pre-stage catalyst 20 is controlled so that the corrected inlet target exhaust temperature of the DPF 21 is obtained. That is, the exhaust gas outlet temperature of the front catalyst 20 is fed back by the temperature sensor 22, and the post injection amount or the fuel injection amount by the injector 27 so that the exhaust gas outlet temperature of the front catalyst 20 becomes the corrected target inlet exhaust gas temperature of the DPF 21. Is controlled (decreased). In this way, by limiting the amount of HC supplied to the DPF 21, the DPF 21 is affected even under conditions where the bed temperature of the DPF 21 during regeneration is maximized, for example, in an operating state where the exhaust gas amount decreases as described above. Can be prevented.

  In the above embodiment, as a target for reducing the post-injection amount or the fuel injection amount by the injector 27, the DPF 21 determines the fuel injection amount by the post-injection or the injector 27 in the initial processing step in which the deterioration of the front catalyst 20 is determined. A description has been given of reducing the fuel injection amount by post injection or the injector 27 by reducing the inlet target exhaust gas temperature of the DPF 21 by reducing it to an allowable HC inflow amount, and then correcting the decrease. However, although not shown, in the initial processing step in which the deterioration of the pre-stage catalyst 20 is determined, the post-injection or the fuel injection amount by the injector 27 is corrected to decrease by correcting the decrease in the target exhaust gas temperature of the DPF 21. Also good.

  In the present embodiment, in addition to the effect (a) in the first embodiment, the following effects can be achieved.

  (A) a pre-stage catalyst 20 having an oxidizing ability provided in an exhaust passage of an internal combustion engine, a particulate filter 21 carrying a catalyst provided downstream of the pre-stage catalyst 20 and capturing particulate matter in the exhaust; A post-injection means as an HC supply means for supplying HC from the upstream side of the upstream catalyst 20 and a fuel injection means by the injector 27, and the particulates reacted by the upstream catalyst 20 are reacted with the HC supplied by the HC supply means. An exhaust purification device for an internal combustion engine that removes particulate matter captured by the filter 21 and regenerates the filter 21; and a deterioration state determination means (steps S3 and S4) for determining the deterioration state of the front catalyst 20; An exhaust target inlet temperature to be supplied to the particulate filter 21 during regeneration of the particulate filter 21 is set. When the deterioration of the pre-stage catalyst 20 is determined by the target air inlet temperature setting means (step S8) and the deterioration state determining means, the exhaust target inlet temperature set by the exhaust target inlet temperature setting means is corrected to decrease. And a control unit 26 as a control means for controlling the amount of HC supplied during regeneration of the particulate filter 21 by the HC supply means so as to maintain the exhaust gas target inlet temperature corrected for the decrease. For this reason, an excessive increase in the temperature of the particulate filter 21 during regeneration can be suppressed.

(Third embodiment)
FIG. 5 is a control flowchart by the controller showing a third embodiment of the exhaust emission control system to which the present invention is applied. In this embodiment, after detecting the deterioration of the pre-stage catalyst, a configuration for reducing the target PM accumulation amount at the start of DPF regeneration is added to the first embodiment. In addition, the same code | symbol is attached | subjected to the same apparatus, member, etc. as 1st Embodiment, and the description is abbreviate | omitted or simplified.

  In FIG. 5, the exhaust gas purification apparatus for an internal combustion engine according to the present embodiment executes the post-injection amount reduction processing of the post injection amount or the fuel injection amount by the injector 27 in step S6 in the control flowchart of the first embodiment. Until completion, the DPF 21 regeneration is executed in the added step S10, and the correction for reducing the target PM accumulation amount for starting the DPF 21 regeneration is executed in the added step S11 thereafter. Accordingly, in the next DPF 21 regeneration process, the regeneration of the DPF 21 is started when the target PM accumulation amount corrected for the decrease is reached. Other configurations are the same as those in the first embodiment.

  The target PM accumulation amount at the start of regeneration of the DPF 21 that performs the decrease correction executed in the step S11 is the PM accumulated in advance in an operating state in which the exhaust gas amount is greatly reduced through experiments or the like and flows through the front catalyst 20. Along with the amount of HC, a value that does not affect the DPF 21 even when burned rapidly is set by simulating.

  Therefore, in this embodiment, when it is determined in step S3 that the pre-stage catalyst 20 has deteriorated more than a predetermined level, first, in steps S4 to S6, the fuel injection amount by the post-injection or the injector 27 is allowed by the DPF 21. To prevent the DPF 21 from being burned out or cracked. In step S10, the DPF 21 regeneration is executed until the current DPF 21 regeneration is completed. Next, in step S11, the target PM accumulation amount of the DPF 21 is corrected to decrease, and the current process is terminated. In the DPF 21 processing after the next time, regeneration of the DPF 21 is started when the target PM accumulation amount for starting the regeneration of the DPF 21 set by correcting the decrease in step S11 in the previous processing routine is reached.

  In this embodiment, the DPF 21 regeneration after the next time is performed under the condition that the bed temperature of the DPF 21 during regeneration is maximized, for example, as described above, because the PM accumulation amount of the DPF 21 is corrected to decrease by the step S11. Even in an operating state in which the gas amount decreases, the DPF 21 can be prevented from being affected.

  In the present embodiment, in addition to the effect (a) in the first embodiment, the following effects can be achieved.

  (C) a pre-stage catalyst 20 having an oxidizing ability provided in an exhaust passage of an internal combustion engine, a particulate filter 21 carrying a catalyst provided downstream of the pre-stage catalyst 20 and capturing particulate matter in the exhaust; Post-injection as HC supply means for supplying HC from upstream of the front stage catalyst 20 or fuel injection means by the injector 27, and reacting the HC supplied by the HC supply means with the front stage catalyst 20, and the particulate filter 21 is an exhaust purification device for an internal combustion engine that removes the particulate matter captured by 21 and regenerates the filter 21; deterioration state determining means (steps S3 and S4) for determining the deterioration state of the pre-stage catalyst 20; Target collection amount setting means (step for setting a target collection amount of particulate matter for starting regeneration of the curate filter 21 11) and a control unit 26 as these control means. The control means regenerates the particulate filter 21 after the determination when the deterioration of the pre-stage catalyst 20 is determined by the deterioration state determination means. In some cases, the amount of HC supplied during regeneration of the particulate filter 21 is reduced by the HC supply means, and the amount of HC passing through the deteriorated pre-stage catalyst 20 and flowing into the particulate filter 21 is reduced to the particulate filter. The amount of HC allowed by 21 is set to be equal to or less than that, and at the time of regeneration of the particulate filter 21 thereafter, the target collection amount at the start of regeneration by the target collection amount setting means is reduced and corrected. For this reason, it is possible to prevent the DPF 21 from being affected under conditions where the bed temperature of the DPF 21 during regeneration is maximized, for example, even in an operating state where the exhaust gas amount is reduced.

The system block diagram of the diesel engine with a supercharger provided with the exhaust gas purification device of the internal combustion engine which shows one Embodiment of this invention. The flowchart of the reproduction | regeneration control by a controller similarly. The time chart which shows each time change state of the temperature of a front | former stage catalyst, the temperature of DPF, and PM deposition amount at the time of DPF reproduction | regeneration in which fuel injection by the post injection or the injector was started. The flowchart of the regeneration control in the exhaust gas purification apparatus of the internal combustion engine which shows 2nd Embodiment of this invention. The flowchart of the regeneration control in the exhaust gas purification apparatus of the internal combustion engine which shows 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine, engine main body 2 Common rail 3 Fuel injection valve 4 Supply pump 5 Combustion chamber 6 EGR passage 7 EGR valve 10 Supercharger 10A Exhaust turbine, turbine 10B Compressor 10C Variable nozzle 11 Exhaust passage 12 Intake passage 20 Pre-stage catalyst, oxidation catalyst 21 Particulate filter, filter, DPF
22, 23 Temperature sensor 24 Differential pressure sensor 26 Control unit 27 Injector

Claims (3)

A pre-stage catalyst having an oxidizing ability provided in an exhaust passage of an internal combustion engine, a particulate filter provided downstream of the pre-stage catalyst and carrying a catalyst that captures particulate matter in the exhaust, and HC from the upstream of the pre-stage catalyst An internal combustion engine that regenerates the filter by causing the HC supplied by the HC supply means to react with the preceding catalyst, removing particulate matter captured by the particulate filter, and regenerating the filter. An exhaust purification device,
A deterioration state determining means for determining a deterioration state of the preceding catalyst;
When the deterioration of the pre-stage catalyst is determined by the deterioration state determining means, the amount of HC supplied during particulate filter regeneration is reduced by the HC supply means, and the particulate is passed through the deteriorated pre-stage catalyst. An exhaust purification device for an internal combustion engine, comprising: control means for setting an HC amount flowing into the filter to be equal to or less than an HC amount allowed by the particulate filter. A target collection amount setting means for setting a target collection amount of the particulate matter for starting regeneration of the particulate filter;
When the deterioration of the pre-stage catalyst is determined by the deterioration state determination means, the control means supplies the HC supply amount supplied during the regeneration of the particulate filter by the HC supply means during regeneration of the particulate filter after the determination. The amount of HC passing through the deteriorated pre-stage catalyst and flowing into the particulate filter is made equal to or less than the amount of HC allowed by the particulate filter, and the target trapping is performed during the subsequent regeneration of the particulate filter. 2. An exhaust emission control device for an internal combustion engine according to claim 1, wherein the target collection amount at the start of regeneration by the collection amount setting means is corrected to decrease. A pre-stage catalyst having an oxidizing ability provided in an exhaust passage of an internal combustion engine, a particulate filter provided downstream of the pre-stage catalyst and carrying a catalyst that captures particulate matter in the exhaust, and HC from the upstream of the pre-stage catalyst An internal combustion engine that regenerates the filter by causing the HC supplied by the HC supply means to react with the preceding catalyst, removing particulate matter captured by the particulate filter, and regenerating the filter. An exhaust purification device,
A deterioration state determining means for determining a deterioration state of the preceding catalyst;
Exhaust target inlet temperature setting means for setting an exhaust target inlet temperature to be supplied to the particulate filter during regeneration of the particulate filter;
When the deterioration of the pre-catalyst is determined by the deterioration state determining means, the exhaust target inlet temperature set by the exhaust target inlet temperature setting means is corrected to be lowered and maintained at the exhaust target inlet temperature corrected for the decrease. An exhaust purification device for an internal combustion engine, comprising: control means for controlling an HC supply amount supplied during regeneration of the particulate filter by the HC supply means.

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