JP2004150389A - Emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent increase of particulates discharged from a vehicle even when collecting efficiency of a trap is lowered accompanying trap regeneration treatment. <P>SOLUTION: When a particulate collection amount in a diesel particulate filter DPF for trapping the particulate in the exhaust gas exceeds a predetermined amount PM1, an exhaust temperature is raised by post injection, and the collected particulates are burned and eliminated. Until the particulate collection amount reaches PM2 which is smaller than PM1 after the particulates are burned and eliminated, a target EGR rate is reduced to be corrected and generation of the particulates in an engine is restrained. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to an exhaust gas recirculation device and an exhaust gas purification device for an internal combustion engine provided with a trap for collecting particulates in exhaust gas.
[0002]
[Prior art]
BACKGROUND ART Conventionally, as an internal combustion engine provided with an exhaust gas recirculation device that recirculates a part of exhaust gas to an intake side of the engine and a trap that collects particulates in the exhaust gas, for example, there is an internal combustion engine disclosed in Patent Document 1. .
[0003]
In this apparatus, when the amount of particulates trapped in the trap increases and the exhaust pressure upstream of the trap increases, a part of the exhaust discharged to the exhaust port flows back into the cylinder when the piston descends. Since the internal EGR increases, control is performed to reduce the exhaust gas recirculation by the exhaust gas recirculation device (hereinafter, referred to as external EGR) in response to the increase in the internal EGR.
[0004]
[Patent Document 1]
JP 05-133286 A
[0005]
[Problems to be solved by the invention]
By the way, the trap has a characteristic that the trapping efficiency of the particulates is reduced in a state where the trapped amount of the particulates is small immediately after the regeneration treatment for removing the trapped particulates is performed.
[0006]
For this reason, when the amount of trapped particulates is small and the trapping efficiency is low immediately after the regeneration is performed, a large amount of particulates is generated by causing the exhaust gas recirculation device to perform a large amount of external EGR in a high engine load and high revolution range. When generated, the amount of particulates discharged from the vehicle through the trap increases.
[0007]
The present invention has been made in view of the above problems, and an internal combustion engine that can prevent an increase in particulates discharged from a vehicle even if trap collection efficiency is reduced due to trap regeneration treatment. An object of the present invention is to provide an exhaust gas purification device.
[0008]
[Means for Solving the Problems]
Therefore, the exhaust gas purification apparatus for an internal combustion engine according to the present invention is configured to reduce and correct the exhaust gas recirculation amount by the exhaust gas recirculation device when the trapped amount of particulates in the trap is equal to or less than a predetermined amount.
[0009]
【The invention's effect】
According to the above configuration, when the trapping amount of the particulates by the trap is smaller than the predetermined amount, the trapping efficiency of the particulates decreases. However, by reducing the exhaust gas recirculation amount (exhaust gas recirculation rate) by the exhaust gas recirculation device, Suppress the generation of particulates.
[0010]
Therefore, even if the trapping efficiency of the particulates in the trap is reduced, it is possible to prevent the particulates discharged from the vehicle from increasing.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system configuration diagram of an internal combustion engine according to the embodiment.
[0012]
In FIG. 1, a fuel injection system of a diesel engine 1 as an internal combustion engine for a vehicle includes a common rail 2, an injector 3 which is supplied with fuel via the common rail 2, and turns on / off fuel injection by an electromagnetic valve. A common rail type fuel injection system including a fuel supply pump 4 for supplying fuel to the common rail 2 is employed.
[0013]
Downstream of an exhaust manifold (not shown), a turbine 5T of a variable nozzle type turbocharger 5 is provided, and a compressor 5C is mounted coaxially with the turbine 5T.
[0014]
The intake air is compressed and pressurized by the compressor 5C, passes through the intercooler 6, and is sucked into each cylinder via the intake collector 7.
A throttle valve 8 is interposed between the intercooler 6 and the intake collector 7.
[0015]
The exhaust passage on the upstream side of the turbine 5T and the intake collector 7 are communicated with each other by an exhaust gas recirculation passage 9, and a part of the exhaust gas is recirculated to the intake collector 7 (intake side) via the exhaust gas recirculation passage 9. ing.
[0016]
An exhaust gas recirculation control valve 10 is interposed in the exhaust gas recirculation passage 9, and the exhaust gas recirculation amount is controlled by the opening degree of the exhaust gas recirculation control valve 10.
The exhaust gas recirculation passage 9 and the exhaust gas recirculation control valve 10 constitute an exhaust gas recirculation device.
[0017]
In the exhaust passage downstream of the turbine 5T, an oxidation catalyst 11, an adsorption type NOx catalyst 12, and a diesel particulate filter (hereinafter abbreviated as DPF) 13 are provided in this order from the upstream side.
[0018]
The oxidation catalyst 11 is a catalyst that supports a noble metal and oxidizes unburned HC and CO in exhaust gas.
The adsorption-type NOx catalyst 12 (exhaust gas purifying means) adsorbs NOx in the exhaust gas when the exhaust air-fuel ratio is lean (oxidizing atmosphere) and adsorbs when the exhaust air-fuel ratio is rich (reducing atmosphere). This is a catalyst that releases the reduced NOx and performs a reduction process.
[0019]
Further, the DPF 13 is a trap for collecting particulates in the exhaust gas. The adsorption-type NOx catalyst 12 is provided with a first temperature sensor 14 for detecting the temperature of the catalyst 12, and an exhaust passage between the adsorption-type NOx catalyst 12 and the DPF 13 is provided with a pressure in the exhaust passage. A pressure sensor 15 for detecting the temperature of the DPF 13; a second temperature sensor 16 for detecting the temperature of the DPF 13; and an air-fuel ratio sensor for detecting an exhaust air-fuel ratio in an exhaust passage downstream of the DPF 13. 17 are provided.
[0020]
Detection signals from the first temperature sensor 14, the pressure sensor 15, the second temperature sensor 16, and the air-fuel ratio sensor 17 are input to an engine control unit (ECU) 20 including a microcomputer.
[0021]
In addition to the detection signal from the sensor, the ECU 20 receives an engine rotation sensor signal, an accelerator opening sensor signal, a variable nozzle sensor signal of the turbocharger 5, and the like.
[0022]
Then, the ECU 20 outputs control signals to the injector 3, the throttle valve 8, the exhaust gas recirculation control valve 10, the variable nozzle (not shown) of the turbocharger 5, and the like by an arithmetic process based on the detection signal.
[0023]
Here, the ECU 20 performs the control shown in the flowcharts of FIGS. 2 to 12 for purifying the exhaust gas. Hereinafter, the exhaust gas purification control will be described in detail with reference to the flowcharts of FIGS.
[0024]
In step S1, the engine rotation and the accelerator opening are read as the engine operating state.
In step S2, the amount of NOx deposited on the adsorption type NOx catalyst 12 is estimated.
[0025]
The NOx accumulation amount can be estimated from the integrated value of the engine speed, for example, as described on page 6 of Japanese Patent No. 2600492, and the NOx accumulation amount every time the vehicle travels a predetermined distance. May be added.
[0026]
In step S3, the amount of sulfur deposited on the adsorption type NOx catalyst 12 is estimated. The sulfur accumulation amount can be estimated from the integrated value of the engine speed, for example, similarly to the NOx accumulation amount.
[0027]
In step S4, the particulate matter (PM) collection amount in the DPF 13 is estimated.
If the trapping amount of the particulates in the DPF 13 increases, the exhaust resistance increases, and the exhaust pressure on the upstream side of the DPF 13 increases. Therefore, the particulate trapping amount is estimated from the exhaust pressure detected by the pressure sensor 15. Can be.
[0028]
Further, the amount of trapped particulates can be estimated from the travel distance since the previous regeneration treatment, or the accumulated engine speed and exhaust pressure.
In step S5, it is determined whether or not the reg flag is 0, thereby determining whether or not the DPF 13 is in the regeneration mode.
[0029]
In the case of the reproduction mode of the DPF 13, since the reg flag is set to 1, the process proceeds from the step S5 to the reproduction mode processing from the step S101.
The regeneration mode after step S101 will be described later in detail. When the regeneration process of the DPF 13 is completed, the target EGR rate decrease mode flag is set to 1 and the target EGR rate decrease mode is requested.
[0030]
If the reg flag is 0 and the DPF 13 is not in the regeneration mode, the process proceeds to step S6, where it is determined whether or not the desul flag is 0 to determine whether or not the adsorption NOx catalyst 12 is in the sulfur poisoning release mode. Is determined.
[0031]
If the adsorption type NOx catalyst 12 is in the sulfur poisoning release mode, the desul flag is set to 1, so that the process proceeds from step S6 to step S201 and subsequent steps.
[0032]
When the desul flag is 0 and the mode is not the sulfur poisoning release mode of the adsorption type NOx catalyst 12, the process proceeds to step S7, where it is determined whether or not the sp flag is 0, so that the adsorption type NOx catalyst 12 is adsorbed by the adsorption type NOx catalyst 12. It is determined whether or not the vehicle is in a rich spike mode for processing NOx.
[0033]
In the case of the rich spike mode of the adsorption type NOx catalyst 12, since the sp flag is set to 1, the flow proceeds to the rich spike mode processing from step S7 to step S301.
[0034]
If the sp flag is 0 and the mode is not the rich spike mode, the process proceeds to step S8, where it is determined whether or not the rec flag is 0 to determine whether or not the melting loss prevention mode is in effect at the time of DPF regeneration and sulfur poisoning release. Determine whether or not.
[0035]
If the mode is the erosion prevention mode, the rec flag is set to 1, so that the process proceeds from the step S8 to the erosion prevention mode processing from step S401.
If the rec flag is 0 and the mode is not the erosion prevention mode, the process proceeds to step S9 to determine whether or not the target EGR rate reduction flag is 0, thereby determining whether or not the target EGR rate reduction mode. .
[0036]
In the case of the target EGR rate decrease mode, the target EGR rate decrease flag is set to 1, so that the process proceeds from the step S9 to the target EGR rate decrease mode processing from the step S501.
[0037]
In the target EGR rate reduction mode, as shown in FIG. 19, a predetermined high load / high rotation range determined according to the main fuel injection amount (engine load) and the engine speed (rpm) is the target EGR rate. It is set in advance as a decrease area.
[0038]
Then, in step S501, it is determined whether the target EGR rate falls in the target EGR rate decreasing area. If the target EGR rate falls in the target EGR rate decreasing area, the target EGR rate is decreased from a normal value in step S502 (see FIG. 20), if it does not fall within the target EGR rate decrease region, a normal value is set as the target EGR rate in step S503.
[0039]
If the target EGR rate reduction flag is 0 and the mode is not the target EGR rate reduction mode, the process proceeds to step S10, where it is determined whether or not the NOx regeneration reduction flag is 0 to determine whether or not the NOx regeneration request reduction mode is set. judge.
[0040]
In the case of the NOx regeneration request shortening mode, the NOx regeneration shortening flag is set to 1, so that the process proceeds from the step S10 to the NOx regeneration request shortening mode process from the step S601.
[0041]
In the NOx regeneration request shortening mode, a value NOx2 smaller than the normal value NOx1 is set as the threshold value of the NOx adsorption amount for issuing the regeneration request in order to shorten the interval of generation of the NOx regeneration request.
[0042]
Then, in step S601, it is determined whether or not the NOx adsorption amount is equal to or less than the threshold value NOx2. If the NOx adsorption amount is equal to or less than the threshold value NOx2, the NOx regeneration request flag sp is set to 0 in step S602. If the NOx adsorption amount exceeds the threshold value NOx2, a NOx regeneration request is issued with the NOx regeneration request flag sp set to 1 in step S603.
[0043]
If the NOx regeneration reduction flag is 0 and the NOx regeneration request reduction mode is not set, the process proceeds to step S11, and it is determined whether or not the amount of particulates accumulated in the DPF 13 exceeds the predetermined amount PM1 and it is time to regenerate.
[0044]
Whether the amount of accumulated particulates has reached the predetermined amount PM1 depends on whether the exhaust pressure upstream of the DPF 13 detected by the pressure sensor 15 under predetermined engine operating conditions (load / rotation) is a threshold value shown in FIG. Is determined to be the regeneration time.
[0045]
Alternatively, a method may be used in which the regeneration timing is determined when the travel distance from the previous regeneration exceeds a predetermined distance and the exhaust pressure exceeds the threshold shown in FIG.
If it is determined that it is the regeneration time, the reg flag which is the DPF regeneration request flag is set to 1 in step S701, and a DPF regeneration request is generated.
[0046]
When the accumulation amount of the particulates is equal to or less than the predetermined amount PM1, the process proceeds to step S12, where the amount of the particulates collected by the DPF 13 exceeds the predetermined amount PM2 (<PM1), and the normal EGR rate mode is changed from the target EGR rate reduction mode. It is determined whether it is time to change to.
[0047]
As shown in FIG. 21, the DPF 13 has a characteristic that the collection efficiency of particulates decreases when the collection amount of particulates is small, and the predetermined amount PM2 has a collection efficiency equal to or higher than a predetermined value. It is set as a threshold value of the particulate collection amount.
[0048]
Whether the amount of accumulated particulates has reached the predetermined amount PM2 depends on whether the exhaust pressure upstream of the DPF 13 detected by the pressure sensor 15 under predetermined engine operating conditions (load / rotation) is a threshold value shown in FIG. Is exceeded, it is determined that it is time to change from the target EGR rate reduction mode to the normal EGR rate mode.
[0049]
Further, a method of determining the mode switching of the EGR rate when the travel distance from the previous regeneration exceeds the predetermined distance and the exhaust pressure exceeds the threshold shown in FIG.
[0050]
If it is determined that it is time to change the target EGR rate reduction mode to the normal EGR rate mode, the target EGR rate reduction mode flag is reset to 0 in step S801, and the NOx regeneration reduction flag is reset to 0 in step S802.
[0051]
If it is determined in step S12 that the amount of accumulated particulates is equal to or less than the predetermined amount PM2, the process proceeds to step S13, in which the amount of sulfur deposited on the adsorptive NOx catalyst 12 reaches the predetermined amount SM1, and the poisoning release timing (regeneration) Time) is determined.
[0052]
If a predetermined amount of sulfur has accumulated and it is determined that sulfur poisoning must be released, a sulfur poisoning release request is generated by setting the sulfur poisoning release request flag desul to 1 in step S901.
[0053]
On the other hand, when the amount of sulfur deposited on the adsorption-type NOx catalyst 12 is equal to or less than the predetermined amount SM1, the process proceeds to step S14, and whether the amount of NOx adsorbed on the adsorption-type NOx catalyst 12 has reached the predetermined amount NOx1 and it is time to regenerate. Determine whether or not.
[0054]
If NOx exceeding the predetermined amount NOx1 is adsorbed on the adsorption-type NOx catalyst 12 and it is determined that NOx regeneration (NOx release / reduction processing) is necessary, a NOx regeneration request flag (rich spike mode flag) is set in step S1001. With sp set to 1, a NOx regeneration request is generated.
[0055]
Here, the reproduction mode of the DPF 13 after step S101 will be described. In the regeneration mode of the DPF 13, the post injection, which is the fuel injection from the latter stage of the expansion stroke to the exhaust stroke, is performed together with the main injection to increase the exhaust temperature. The post injection increases the exhaust gas temperature. The target excess air ratio is controlled to a target excess air ratio (hereinafter, the excess air ratio is abbreviated as λ) corresponding to the trapped amount.
[0056]
The control of the exhaust λ is performed by controlling the opening degree of the throttle valve 8 according to a map value of a target intake air amount according to the main injection amount and the engine speed (rpm). As shown in FIG. 17, the exhaust λ is made smaller (richer) as the amount of particulates deposited increases.
[0057]
When the actual exhaust λ detected by the air-fuel ratio sensor 17 deviates from the target in the intake throttle according to the target intake air amount, the intake throttle is feedback-controlled to control the target exhaust λ.
[0058]
In step S102, it is determined whether or not the DPF temperature detected by the temperature sensor 16 is equal to or higher than the upper limit T1 during regeneration.
When the DPF temperature becomes equal to or higher than the upper limit value T1 during the regeneration, the process proceeds to step S111, in which, for example, as shown in FIG.
[0059]
If the DPF temperature is lower than the upper limit T1 during regeneration, the process proceeds to step S103, and it is determined whether the DPF temperature is equal to or lower than the lower limit T1 during regeneration.
When the DPF temperature becomes equal to or lower than the lower limit value T1 during regeneration, the process proceeds to step S110, in which the post injection amount is increased by a predetermined amount, and the exhaust gas temperature is raised.
[0060]
If the post injection amount fluctuates in step S110 and step S111 and the exhaust λ deviates from the target, the exhaust λ is adjusted by the intake throttle to achieve the target exhaust λ.
[0061]
On the other hand, if the DPF temperature is less than the upper limit value T1 during regeneration and exceeds the lower limit value T1, the process proceeds to step S104, and whether or not the elapsed time t1 from the start of post-injection is equal to or longer than a predetermined time tdpfreg. Is determined.
[0062]
When the elapsed time t1 is equal to or longer than the predetermined time tdpfreg, it is determined that the particulates collected in the DPF 13 have been burned and removed, and the post-injection is stopped in step S105 to stop heating the DPF 13.
[0063]
In step S106, since the regeneration mode of the DPF 13 has ended, the reg flag is reset to 0.
In step S107, if the unburned particulates remain in the DPF 13 even though the regeneration mode ends, if the exhaust λ is suddenly increased, the particulates remaining in the DPF 13 may be burned at once, and the DPF 13 may be melted. , Set the rec flag to 1 to enter the erosion prevention mode.
[0064]
Further, in step S108, immediately after the regeneration of the DPF 13, in order to suppress the generation of particulates in the engine, the target EGR rate reduction flag is set to 1 and the mode for reducing the target EGR rate is entered.
[0065]
As shown in FIG. 21, when the amount of particulates collected immediately after regeneration is small, the DPF 13 has a low collection efficiency, and there is a probability that the particulates pass through the DPF 13 though there is a capacity to be collected. Get higher.
[0066]
Therefore, the exhaust gas recirculation rate (EGR rate) is reduced to reduce the amount of particulates generated in the engine 1 so that the amount of particulates released from the vehicle does not increase even if the collection efficiency in the DPF 13 is low. .
[0067]
In particular, in a high-load and high-speed range, the amount of particulates generated by the engine increases, so that the effect of a decrease in collection efficiency is great. As described above, the target EGR rate is reduced in a high-load and high-speed range. (See FIGS. 19 and 20).
[0068]
In step S109, the NOx regeneration shortening flag is set to 1 in response to entering the mode for reducing the target EGR rate.
The NOx regeneration reduction flag is determined in step S10. If the NOx regeneration reduction flag is 1, a value NOx2 smaller than the normal value NOx1 is set as a threshold value of the NOx adsorption amount for issuing a NOx regeneration request. Then, the execution interval of the NOx regeneration process is shortened.
[0069]
Since the above-described estimation of the NOx adsorption amount based on the engine speed and the traveling distance is normally adapted to the case where the EGR rate is controlled, the exhaust gas recirculation rate (EGR rate) is reduced as the collection efficiency of the DPF 13 decreases. When the amount of NOx generated in the engine 1 increases due to the decrease in the normal value, the estimated value of the NOx adsorption amount becomes smaller than the actual value.
[0070]
At this time, if the threshold value of the NOx adsorption amount for issuing the NOx regeneration request is kept at the normal value, the regeneration request is not issued even though the NOx adsorption amount is already saturated, and the NOx emission amount from the vehicle is not increased. Will increase.
[0071]
Therefore, the threshold value of the NOx adsorption amount for issuing the NOx regeneration request is lowered to compensate for the difference between the estimated value and the actual value, so that the NOx amount is not left in a saturated state. .
[0072]
The target EGR rate decrease flag is reset to 0 based on the determination that the sufficient collection efficiency can be exerted when the amount of trapped particulates in the DPF 13 exceeds the predetermined amount PM2 (step S801) Also, since the target EGR rate is returned to the normal value, the NOx regeneration reduction flag is also reset to 0 at the same time (step S802).
[0073]
Next, the sulfur poisoning release mode after step S201 will be described.
First, in step S201, since the amount of sulfur deposited on the adsorption-type NOx catalyst 12 has reached a predetermined amount, the exhaust λ is controlled to stoichiometric (stoichiometric air-fuel ratio).
[0074]
Specifically, as shown in FIG. 15, a map storing a target intake air amount for an operation in which λ = 1 (the stoichiometric air-fuel ratio) is stored in accordance with the main injection amount and the engine speed (rpm). Referring to the reference, the intake air is throttled so as to reach the target intake air amount, and when the actual exhaust λ deviates from the stoichiometric value, the exhaust λ is adjusted using the intake throttle.
[0075]
In step S202, it is determined whether the temperature of the adsorption-type NOx catalyst 12 detected by the temperature sensor 14 is equal to or higher than a predetermined value T3.
For example, when a Ba-based catalyst is used as the adsorption type NOx catalyst 12, the catalyst temperature must be set to 600 ° C. or more in a rich to stoichiometric atmosphere in order to release sulfur poisoning. Set to ° C or higher.
[0076]
If the temperature of the adsorption-type NOx catalyst 12 is lower than the predetermined value T3, the process proceeds to step S209, and a predetermined post injection is performed.
Although the exhaust λ fluctuates due to the post-injection, the target exhaust λ and the target catalyst temperature are realized by adjusting the intake air amount again in step S201.
[0077]
If the temperature of the adsorption type NOx catalyst 12 is equal to or more than the predetermined value T3, the process proceeds to step S203, and it is determined whether the sulfur poisoning release processing at the target exhaust λ and the catalyst temperature has been performed for a predetermined time tdesul. .
[0078]
When the sulfur poisoning release process is performed for a predetermined time tdesul, it is determined that the sulfur poisoning release has been completed, and the process proceeds to step S204 to release the stoichiometric operation.
In step S205, although the sulfur poisoning release mode is ended, if the particulate matter is deposited on the DPF 13 under such a high temperature condition and the exhaust λ is suddenly increased, the particulate matter burns at a stretch in the DPF 13. Since the DPF 13 may be melted, the rec flag is set to 1 in order to enter the melting prevention mode.
[0079]
In step S206, since the sulfur poisoning release mode has ended, the desul flag is reset to 0.
In step S207, since the sulfur poisoning release mode has ended, the sulfur accumulation amount on the adsorption-type NOx catalyst 12 is reset to zero.
[0080]
In step S208, when the sulfur poisoning is released, the adsorption type NOx catalyst 12 is exposed to the stoichiometric atmosphere for a long time, so that the NOx regeneration (NOx release / reduction processing) is performed at the same time. The sp flag indicating the request of the rich spike mode for processing the NOx adsorbed on the catalyst 12 is reset to 0.
[0081]
Next, the rich spike mode after step S301 will be described.
In step S301, the exhaust λ is controlled to a predetermined λ for performing a rich spike.
[0082]
In step S302, it is determined whether or not the elapsed time t3 of the start of the rich spike is equal to or longer than a predetermined time tspike.
When the predetermined time tspike has elapsed, the process proceeds to step S303 to cancel the rich operation, reset the sp flag to 0, and end the rich spike mode.
[0083]
Next, the melting prevention mode after step S401 will be described.
In step S401, the temperature of the DPF 13 is detected.
In step S402, since the temperature of the DPF 13 is very high immediately after the regeneration or immediately after the high-load operation, the exhaust λ is set to a predetermined value so that the unburned or accumulated particulates do not burn at a stretch and the DPF 13 is melted. It is controlled to a value (for example, λ ≦ 1.4).
[0084]
Specifically, as shown in FIG. 16, the target intake air amount is set according to the main injection amount and the engine speed, the intake throttle is controlled based on the target intake air amount, and the output of the air-fuel ratio sensor 17 Feedback control of air volume.
[0085]
In step S403, it is determined whether or not the temperature of the DPF 13 detected by the temperature sensor 16 is equal to or lower than a temperature T4 at which there is no possibility that rapid oxidation of particulates will start.
[0086]
If the temperature is lower than the temperature T4, the DPF 13 can be prevented from being damaged even when the oxygen concentration in the exhaust gas becomes substantially equal to that in the atmosphere.
When the temperature of the DPF 13 becomes equal to or lower than the temperature T4, there is no possibility that the DPF 13 is melted. Therefore, the process proceeds to Step S404, and the exhaust λ control for preventing the damage is stopped.
[0087]
In step S405, since the erosion prevention mode has ended, the rec flag is reset to 0.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an engine according to an embodiment.
FIG. 2 is a flowchart showing a main routine of exhaust gas purification control.
FIG. 3 is a flowchart showing a DPF regeneration mode.
FIG. 4 is a flowchart showing a sulfur poisoning release mode of the adsorption type NOx catalyst.
FIG. 5 is a flowchart showing a rich spike mode for NOx regeneration of an adsorption-type NOx catalyst.
FIG. 6 is a flowchart illustrating a DPF melting prevention mode.
FIG. 7 is a flowchart showing a target EGR rate reduction mode.
FIG. 8 is a flowchart showing a NOx regeneration request shortening mode.
FIG. 9 is a flowchart showing a setting of a DPF regeneration mode.
FIG. 10 is a flowchart showing release of a target EGR rate reduction mode.
FIG. 11 is a flowchart showing the setting of a sulfur poisoning release mode.
FIG. 12 is a flowchart illustrating setting of a rich spike mode.
FIG. 13 is a diagram showing a map of an exhaust pressure threshold value used for determining a DPF regeneration timing.
FIG. 14 is a view showing a map of an exhaust pressure threshold value used for determination of cancellation of a target EGR rate decrease mode.
FIG. 15 is a diagram showing a map of a target intake air amount for λ = 1 operation.
FIG. 16 is a diagram showing a map of a target intake air amount for preventing DPF melting.
FIG. 17 is a diagram showing a correlation between a target exhaust λ during DPF regeneration and a trapped amount of particulates.
FIG. 18 is a diagram showing a map of a unit post injection amount for raising the exhaust gas temperature.
FIG. 19 is a diagram showing a target EGR rate decrease correction region.
FIG. 20 is a diagram showing a target EGR rate in a decrease correction region.
FIG. 21 is a diagram showing a correlation between a particulate collection amount and a collection efficiency.
[Explanation of symbols]
1. Diesel engine (internal combustion engine)
3. Injector
8 ... Throttle valve
9 Exhaust gas recirculation passage
10. Exhaust gas recirculation control valve
11 ... oxidation catalyst
12. Adsorption type NOx catalyst (exhaust gas purifying means)
13 ... DPF (trap)
14 first temperature sensor
15 ... Pressure sensor
16 second temperature sensor
17 ... Air-fuel ratio sensor
20 ... ECU

Claims (6)

An internal combustion engine including an exhaust gas recirculation device that recirculates a part of exhaust gas to an intake side of the engine, and a trap that is interposed in an exhaust passage of the engine and collects particulates in exhaust gas,
An exhaust gas purification device for an internal combustion engine, wherein the amount of exhaust gas recirculated by the exhaust gas recirculation device is reduced and corrected when the amount of trapped particulates in the trap is equal to or less than a predetermined amount. When the trapping amount of the particulates in the trap is smaller than a predetermined amount, and when the engine is operated in a predetermined high load / high rotation range, the exhaust gas recirculation device reduces and corrects the exhaust gas recirculation amount. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein: Exhaust purification means interposed in the exhaust passage and purifying exhaust components other than the particulates,
3. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein when the decrease correction of the exhaust gas recirculation amount is performed, an execution interval of a regeneration process of the exhaust gas purifying unit is corrected to be short. 4. The exhaust gas purifying apparatus for an internal combustion engine according to claim 3, wherein said exhaust gas purifying means is an adsorption type NOx catalyst that adsorbs NOx in exhaust gas in an oxidizing atmosphere and releases NOx in a reducing atmosphere. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the correction of the decrease in the exhaust gas recirculation amount is performed immediately after the regeneration of the trap. The method according to claim 1, wherein when the exhaust pressure in the trap is equal to or less than a predetermined value, it is determined that the trapping amount of the particulates in the trap is smaller than a predetermined amount. Exhaust purification device for internal combustion engine.

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