JP2004324454A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine, in which forced regeneration of DPF and S purging of an NOx occluded catalyst can be performed at the same time. <P>SOLUTION: The device is provided with a suction passage 8 and an exhaust passage communicating with a cylinder of the internal combustion engine, a supercharger 14 and a suction throttle means 10, the NOx occluded catalyst 22 prepared at the exhaust passage, occluding NOx in the exhaust emission at the time of lean operation, and discharging and reducing the occluded NOx by rich operation, a filter 23 for collecting particulate matter in the exhaust emission, a secondary air supply passage 30 for introducing air for regeneration of the filter from the suction upstream side of the suction throttle means into the exhaust upstream side of the filter, and an exhaust emission control means 46 for controlling the air quantity of the second air supply passage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas purification device for an internal combustion engine, and more particularly, to an exhaust gas purification device for an internal combustion engine applied to simultaneous regeneration of a NOx storage catalyst and a diesel particulate filter (DPF).
[0002]
[Prior art]
Generally, a NOx storage catalyst is an exhaust gas aftertreatment device that stores NOx in exhaust gas at a lean air-fuel ratio and releases and reduces the stored NOx at a rich air-fuel ratio.
Specifically, it has a characteristic of storing NOx in exhaust gas as a nitrate in an excess oxygen state (oxidizing atmosphere) and reducing the stored NOx to nitrogen in a excess carbon monoxide state (reducing atmosphere). The internal combustion engine periodically switches to a rich operation in which the excess air ratio is low (low λ) such that the exhaust air-fuel ratio is controlled to a stoichiometric air-fuel ratio or a value close to the stoichiometric air-fuel ratio before the NOx storage amount is saturated. To regenerate the NOx storage catalyst.
[0003]
Further, since SOx resulting from oxidation of the S component in the fuel is also deposited as sulfate on the NOx storage catalyst, the rich spike operation is periodically performed as described above in order to release the deposited S component (S purge). To regenerate the NOx storage catalyst.
Here, since the S purge requires a high temperature of about 650 ° C. and a rich or stoichiometric exhaust gas, the NOx storage catalyst uses an intake air for reducing fuel consumption in order to realize the S purge condition. Although a method of combining the throttle with the exhaust gas recirculation (EGR) cut and the post injection is known, there is a problem that the pumping loss caused by the intake throttle causes fuel consumption to deteriorate.
[0004]
Then, a technique of an exhaust gas purification device for an internal combustion engine that overcomes this situation has been proposed (for example, see Patent Document 1).
In this device, when releasing and reducing the stored NOx, the fuel injection amount is increased with respect to the torque decrease due to the pumping loss, and the gas is introduced by the EGR to prevent deterioration of fuel efficiency.
[0005]
On the other hand, the DPF is an exhaust gas post-treatment device that collects and processes particulate matter (PM) in exhaust gas. Specifically, since exhaust gas from a diesel engine or the like contains a large amount of PM in addition to HC, CO, NOx, etc., after collecting the PM in a filter, the exhaust gas of about 600 ° C. Recycle DPF by incineration and removal using exhaust gas.
[0006]
Here, in the DPF, the self-regeneration can be realized depending on the operating conditions, but a forced regeneration system for forcibly increasing the temperature of the DPF is indispensable when all the operating conditions are assumed. However, in this forced regeneration, for example, if the temperature of the DPF is too low, the regeneration speed is slow, and if it is too high, the DPF is damaged due to rapid regeneration, which makes it difficult to control the temperature. Therefore, in the DPF, a technique of an exhaust gas purification device for an internal combustion engine that controls the regeneration speed of the DPF by controlling the air-fuel ratio of the internal combustion engine has been proposed (for example, see Patent Document 2).
[0007]
In this device, the exhaust system is provided with a NOx storage catalyst and a DPF, and during forced regeneration of the DPF, the combustion of PM is suppressed by setting a rich air-fuel ratio until the DPF reaches a predetermined temperature. Until a predetermined time from the desorption temperature is reached, the rich air-fuel ratio is set and the S poisoning is released. As a result, compatibility between requirements for drivability and exhaust gas and excess air ratio for DPF regeneration is achieved.
[0008]
[Patent Document 1]
JP-A-10-184418 (paragraph numbers 0016 to 0023, etc.)
[Patent Document 2]
JP-A-2002-213229 (paragraph numbers 0015 to 0020, FIG. 1 and the like)
[0009]
[Problems to be solved by the invention]
By the way, the forced regeneration of the DPF and the S-purge of the NOx storage catalyst are common in that, as described above, both can be performed using high-temperature exhaust gas that has reached about 650 ° C.
Therefore, it is conceivable that the forced regeneration of the DPF and the S-purge of the NOx storage catalyst are simultaneously performed. The former requires exhaustion in a lean atmosphere for soot oxidation, whereas the latter requires exhaustion in a stoichiometric or rich atmosphere. Therefore, it is generally considered that it is generally difficult to carry out these steps simultaneously.
[0010]
Further, in order to control the regeneration speed of the DPF, it is desired to freely control the excess air ratio of the exhaust gas, but the degree of freedom is small regarding the excess air ratio of the exhaust gas from the internal combustion engine. Therefore, in view of this point, it is generally considered difficult to simultaneously perform the forced regeneration of the DPF and the S purge of the NOx storage catalyst.
However, if it is possible to simultaneously perform the forced regeneration of the DPF and the S purge of the NOx storage catalyst, the total regeneration time required for the regeneration can be shortened, and the deterioration of fuel efficiency can be further prevented. become.
[0011]
Here, in the conventional technology, in particular, in the exhaust gas purifying apparatus for an internal combustion engine described in Patent Document 2, when performing the S purge, after the DPF exceeds a predetermined temperature, the rich state is maintained until a predetermined time elapses. The air-fuel ratio is maintained and then switched to a lean air-fuel ratio. That is, first, the S purge is performed without performing the forced regeneration of the DPF, and then the forced regeneration of the DPF is performed without performing the S purge. Therefore, the forced regeneration of the DPF and the S purge of the NOx storage catalyst are performed. Cannot be implemented at the same time.
[0012]
In other words, the total regeneration time in this case starts from the point in time when the DPF exceeds a predetermined temperature, the S poisoning is released by permitting the S purge, and then the exhaust gas is switched to a lean atmosphere to perform the forced regeneration of the DPF. There is a problem that the time is required to be completed after the operation is performed, which is prolonged. That is, in the above-described conventional technology, there is still a problem in preventing deterioration of fuel efficiency.
[0013]
Further, in the exhaust gas purifying apparatus for an internal combustion engine described in Patent Document 2, when exhaust gas with a high temperature and a lean atmosphere is realized by EGR cut and post injection for DPF regeneration, an excess air ratio of exhaust gas from the internal combustion engine is obtained. Is not controlled, the NOx emission from the internal combustion engine increases, and there is a problem that the exhaust gas performance is adversely affected.
The present invention has been made in view of such a problem, and an object of the present invention is to provide an exhaust gas purification device for an internal combustion engine that can simultaneously perform forced regeneration of a DPF and S purge of a NOx storage catalyst.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, an exhaust gas purifying apparatus for an internal combustion engine according to claim 1 includes an intake passage and an exhaust passage communicating with a cylinder of the internal combustion engine, a supercharger and intake throttle means provided in the intake passage, A NOx storage catalyst that is provided in the exhaust passage and stores NOx in the exhaust during the lean operation and releases and reduces the stored NOx by performing the rich operation. A filter for collecting the curated matter, a secondary air supply passage for introducing air for regeneration of the filter from an intake upstream side of the intake throttle means to an exhaust upstream side of the filter, and an air amount of the secondary air supply passage. Exhaust purification control means.
[0015]
Therefore, according to the exhaust gas purifying apparatus for an internal combustion engine, the NOx storage catalyst is installed on the exhaust gas upstream side and the DPF is installed on the downstream side thereof, and the secondary air is taken out from the upstream of the intake throttle means. Since it is introduced between the catalyst and the DPF, high-temperature and stoichiometric or rich atmosphere exhaust gas from the internal combustion engine can be introduced into the NOx storage catalyst to perform S purge, and at the same time, the stoichiometry that has passed through the NOx storage catalyst Alternatively, secondary air is merged with the exhaust gas in the rich atmosphere to generate exhaust gas in the lean atmosphere, and the exhaust gas in the lean atmosphere can be introduced into the DPF to perform forced regeneration. That is, the forced regeneration of the DPF and the S purge of the NOx storage catalyst can be performed simultaneously. As a result, the total regeneration time is shortened, and deterioration of fuel efficiency is further prevented.
[0016]
Further, the invention according to claim 2 is characterized in that a temperature sensor or an air-fuel ratio sensor for controlling the amount of air is provided downstream of the exhaust gas of the filter. As described above, the exhaust gas purification control means uses the excess air existing on the upstream side of the intake throttle means as the air for regeneration of the DPF, and controls the amount of air according to the state of the exhaust gas downstream of the DPF. The playback speed can be appropriately controlled.
[0017]
Further, in the invention according to claim 3, the exhaust gas purification control means further controls the air-fuel ratio in the cylinder, and a temperature sensor or an air-fuel ratio sensor is provided on the exhaust gas upstream side of the NOx storage catalyst. And
As described above, since the exhaust gas purification control unit also controls the exhaust air-fuel ratio from the internal combustion engine in accordance with the state of the exhaust gas upstream of the NOx storage catalyst, the three-way function of the NOx storage catalyst can be used. , NOx is reliably purified, and the exhaust gas performance is improved.
[0018]
In the invention described in claim 4, the internal combustion engine includes an EGR passage communicating the intake passage and the exhaust passage, and the exhaust gas purification control means includes NOx stored in the NOx storage catalyst and S component adhering to the NOx storage catalyst. It is characterized in that the exhaust gas recirculation through the EGR passage is suppressed when the exhaust gas is discharged and when the particulate matter collected in the filter is incinerated and removed.
[0019]
Thereby, since the control of the amount of secondary air and the control of the exhaust air-fuel ratio from the internal combustion engine by the exhaust gas purification control means are not affected by the EGR gas, the performance of the NOx storage catalyst can be reduced without sacrificing the exhaust gas performance. The S purge and the forced regeneration of the DPF can be performed simultaneously and appropriately.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an engine system configuration diagram including a multi-cylinder diesel engine (hereinafter, simply referred to as an engine) 1 to which an exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present invention is applied. The configuration of the exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described based on FIG.
[0021]
Each cylinder 2 of the engine 1 has a fuel supply system having a common rail type fuel injection device, an intake passage 8 through which intake air is introduced into the combustion chamber 4 by opening an intake valve 6, and an opening of an exhaust valve 18. The valve is connected to an exhaust passage 20 through which exhaust gas from the combustion chamber 4 is led out.
An air cleaner 16 is connected to the most upstream portion of the intake passage 8, and a supercharger 14 is interposed downstream thereof. A throttle valve (intake throttle means) 10 and a surge tank 12 are arranged downstream of the supercharger 14 in this order. The throttle valve 10 is a so-called drive-by-wire type throttle valve (ETV), and its opening is changed according to the engine operating state.
[0022]
On the other hand, a NOx storage catalyst 22 is connected downstream of the exhaust passage 20. The NOx storage catalyst 22 stores NOx in exhaust when the exhaust air-fuel ratio is lean, and releases the stored NOx when the exhaust air-fuel ratio is rich and a reducing agent (HC or CO) exists in the exhaust. This NOx storage catalyst has a known structure. In this embodiment, NOx is released and reduced by post injection.
[0023]
A DPF (filter) 23 is connected downstream of the NOx storage catalyst 22. The DPF 23 captures PM in the exhaust gas, incinerates and removes the PM with high-temperature exhaust gas, and regenerates the PM. This DPF also has a known configuration.
An exhaust circulation passage (EGR passage) 24 branches and extends from the exhaust passage 20, and a part of the exhaust gas (EGR gas) is recirculated into the intake passage 8 to suppress the emission of NOx. The distal end of the EGR passage 24 is connected to the intake passage 8 at the surge tank 12 on the downstream side of the position of the ETV 10 in the intake passage 8. An EGR cooler 26 for cooling EGR gas and an EGR valve 28 electrically connected to an electronic control unit (ECU) 44 are provided in the EGR passage 24. The channel area is adjusted.
[0024]
Here, a secondary air supply passage 30 branches off and extends from the intake passage 8, and a part of the intake air is introduced into the DPF 23 to be used for regeneration of the DPF 23. The front end 32 of the secondary air supply passage 30 is opened between the NOx storage catalyst 22 and the DPF 23, and the rear end 31 of the secondary air supply passage 30 is located upstream of the position where the ETV 10 is provided. It is open to. The secondary air supply passage 30 is provided with a secondary air valve 33 electrically connected to the ECU 44, and the flow area of the secondary air supply passage 30 is adjusted by opening and closing the secondary air valve 33.
[0025]
The ETV 10 is also electrically connected to the ECU 44, and adjusts the EGR gas amount during normal control by adjusting the flow passage area of the intake passage 8. Then, fresh air from the air cleaner 16 enters the intake passage 8 via the supercharger 14, is adjusted by the ETV 10, merges with the EGR gas, and is guided into the combustion chamber 4 of each cylinder 2. When the combustion of the fuel is completed, the exhaust gas is discharged to the exhaust passage 20 and sent to the NOx storage catalyst 22 and the DPF 23.
[0026]
On the other hand, in the ETV 10, during the simultaneous regeneration control, fresh air from the air cleaner 16 enters the intake passage 8 via the supercharger 14, is adjusted by the ETV 10, and is sent to the DPF 23 via the secondary air supply passage 30. Can be As described above, the air existing upstream of the ETV 10 is used as surplus air for the regeneration air of the DPF 23. This is because when the ETV 10 is narrowed to a degree that suppresses PM generation, high-pressure air exists upstream of the ETV 10, and a part of this air is considered to be excess air. In this case, the exhaust pressure (turbine upstream pressure) can be relatively reduced, which also leads to an improvement in fuel efficiency.
[0027]
Here, an airflow sensor 34 is provided at an appropriate position downstream of the air cleaner 16 in the intake passage 8. In the exhaust passage 20, a temperature sensor 36 and an A / F sensor (air-fuel ratio sensor) 38 are disposed at appropriate positions on the upstream side of the NOx storage catalyst 22, and the temperature T1 of the exhaust gas from the engine 1 and the temperature T1. The exhaust air-fuel ratio λ1 is detected. In the exhaust passage 20, a temperature sensor 40 and an A / F sensor (air-fuel ratio sensor) 42 are disposed at appropriate positions on the downstream side of the DPF 23, and the temperature T2 of exhaust gas passing through the DPF 23 and the exhaust air-fuel ratio λ2 are detected.
[0028]
On the input side of the ECU 44, in addition to the temperature sensor 36, the A / F sensor 38, the temperature sensor 40 and the A / F sensor 42, various sensors for detecting the operating state of the engine 1, such as the air flow sensor 34, are electrically connected. It is connected. On the other hand, on the output side of the ECU 44, various actuators of the ETV 10, the EGR valve 28, and the secondary air valve 33 described above are electrically connected.
[0029]
Here, in particular, the ECU 44 includes an exhaust gas purification control unit 46 (exhaust gas purification control means). The exhaust purification control unit 46 controls the amount of air introduced from the secondary air supply passage 30 to the DPF 23, the function of controlling the exhaust air-fuel ratio of the engine 1, the S-purging of the NOx storage catalyst 22, It has a function of controlling the amount of EGR gas during simultaneous regeneration control with forced regeneration of the DPF 23.
[0030]
That is, during normal control of the engine 1, the exhaust gas purification control unit 46 stores NOx in exhaust gas in the oxidizing atmosphere in the NOx storage catalyst 22 while simultaneously performing S purge of the NOx storage catalyst 22 and forced regeneration of the DPF 23. During control, additional fuel is injected after the compression top dead center, etc., and a rich spike is performed to introduce high-temperature and stoichiometric or rich atmosphere exhaust gas from the engine 1 to the NOx storage catalyst 22, and the stored NOx is released and reduced in a reducing atmosphere. The NOx storage catalyst 22 is regenerated by releasing the attached S component in a reducing atmosphere, and the exhaust gas of the stoichiometric or rich atmosphere passing through the NOx storage catalyst 22 and the secondary air from the secondary air supply passage 30 are discharged. To generate exhaust in a lean atmosphere, and the exhaust in the lean atmosphere is introduced into the DPF 23 for forced regeneration. There.
[0031]
More specifically, the exhaust gas purification control unit 46 reads the exhaust gas temperature T1 on the exhaust gas upstream side of the NOx storage catalyst 22 by the temperature sensor 36, recognizes the current temperature of the NOx storage catalyst 22, and sets the A / F sensor The current exhaust air-fuel ratio of the engine 1 is recognized by reading the exhaust air-fuel ratio λ1 of the NOx storage catalyst 22 on the exhaust upstream side of the NOx storage catalyst 38.
As a result, the exhaust air-fuel ratio of the engine 1 can be set to a stoichiometric or rich atmosphere, and NOx is reliably purified using the three-way function of the NOx storage catalyst 22.
[0032]
Further, the exhaust gas purification control unit 46 reads the exhaust gas temperature T2 on the exhaust gas downstream side of the DPF 23 by the temperature sensor 40 to recognize the current temperature of the DPF 23, and also detects the exhaust air on the exhaust gas downstream side of the DPF 23 by the A / F sensor 42. By reading the fuel ratio λ2, the current exhaust air-fuel ratio immediately before the DPF 23 is recognized. As a result, the regeneration speed of the DPF 23 is appropriately controlled, thereby preventing the amount of heat generated by the combustion of PM from suddenly increasing and causing damage to the DPF 23.
[0033]
Next, the operation of the exhaust gas purification device will be described.
FIG. 2 is a flowchart of the simultaneous regeneration control and the like in the exhaust gas purification control unit 46. In step S201 of the figure, the travel distance of the vehicle is read, and in step S202, the exhaust gas temperature T1 on the exhaust gas upstream side of the NOx storage catalyst 22 and the exhaust gas temperature T2 on the exhaust gas downstream side of the DPF 23 are read, and the process proceeds to step S203.
[0034]
In step S203, it is determined whether any of S purge of the NOx storage catalyst 22 and forced regeneration of the DPF 23 is required. For example, if the travel distance of the vehicle is 200 to 300 km and the exhaust temperature is When it is determined that regeneration is necessary, such as when both T1 and the exhaust gas temperature T2 are as high as about 650 ° C., that is, when the determination is YES, the process proceeds to step S204, and the EGR valve 28 is closed. To step S205. This is to prevent the EGR gas from affecting the air amount control of the secondary air and the control of the exhaust air-fuel ratio from the engine 1.
[0035]
In step S205, first, in order to perform the S purge, the exhaust air-fuel ratio λ1 on the upstream side of the NOx storage catalyst 22 is set to stoichiometric or rich, and the engine 1 is instructed to generate exhaust gas having a high temperature and the same atmosphere. Then, the process proceeds to step S206.
In step S206, in parallel with the execution of the S purge, the secondary air valve 33 is opened to execute the regeneration of the DPF 23. In step S207, the exhaust air-fuel ratio λ2 on the downstream side of the DPF 23 is set to lean. Proceed to S208.
[0036]
In step S208, the exhaust gas temperature T1, the exhaust gas temperature T2, and the detected values of the exhaust air-fuel ratio λ1 and the exhaust air-fuel ratio λ1 are fed back as appropriate to perform simultaneous regeneration control with S purge of the NOx storage catalyst 22 and forced regeneration of the DPF 23. This control is performed until the poisoning is released and the PM is removed, for example, until a predetermined time has elapsed, and the routine exits.
[0037]
On the other hand, if it is determined in step S203 that the regeneration is not necessary, the process proceeds to step S209, the secondary air valve 33 is closed, the exhaust air-fuel ratio λ1 is set to lean in step S210, and the process proceeds to step S211. Then, the EGR valve 28 is opened, and in step S212, normal control for the diesel engine is performed, and the routine exits.
[0038]
As described above, in the present invention, the S purge of the NOx storage catalyst 22 can be performed, and at the same time, the forced regeneration of the DPF 23 can be performed. The required time, that is, the total regeneration time is shortened, and the fuel consumption can be significantly prevented from deteriorating as compared with, for example, the case where post-injection is performed.
[0039]
Further, even during the forced regeneration of the DPF 23, since the NOx storage catalyst 22 purifies NOx, it is possible to prevent the exhaust gas performance from deteriorating during the regeneration.
Further, the regeneration speed of the DPF 23 can be freely controlled only by the degree of opening and closing of the secondary air valve 33, that is, it can be performed independently of the control of the exhaust air-fuel ratio for the engine 1. Danger such as breakage can be reduced.
[0040]
The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the A / F sensor 42 is installed downstream of the DPF 23 in order to feedback-control the amount of secondary air, but instead, the A / F sensor 42 is controlled by the air flow sensor 34 and the fuel supply system. The air-fuel ratio calculated from the fuel injection amount may be used. In this case, the same effect as described above can be obtained.
[0041]
In the above-described embodiment, the A / F sensor 38 is provided to control the exhaust air-fuel ratio from the engine 1. However, an O ₂ sensor may be provided instead. An upstream temperature sensor (upstream or downstream of the supercharger 14) may be used for the S purge control of the NOx storage catalyst 22.
Further, when an intercooler is installed in the intake passage 8, the rear end portion 31 of the secondary air supply passage 30 may be disposed upstream of the intercooler so that the temperature of the secondary air does not drop too much.
[0042]
The engine is preferably a diesel engine, but is not limited to this. The exhaust gas purifying apparatus for an internal combustion engine of the present invention is applicable to all engine systems that have a NOx storage catalyst in an exhaust passage and can perform a rich operation. Can be done.
[0043]
【The invention's effect】
As can be understood from the above description, according to the exhaust gas purifying apparatus for an internal combustion engine according to the first aspect of the present invention, the NOx storage catalyst is installed on the upstream side of the exhaust gas, the DPF is installed on the downstream side thereof, and Since secondary air is taken out from the upstream and introduced between the NOx storage catalyst and the DPF, high-temperature and stoichiometric or rich exhaust gas from the internal combustion engine can be introduced into the NOx storage catalyst to perform S purge. At the same time, secondary air is combined with exhaust gas in the stoichiometric or rich atmosphere that has passed through the NOx storage catalyst to generate lean exhaust gas, and the lean exhaust gas can be introduced into the DPF to perform forced regeneration. That is, the forced regeneration of the DPF and the S purge of the NOx storage catalyst can be performed simultaneously. As a result, the total regeneration time can be shortened, and the deterioration of fuel efficiency can be further prevented.
[0044]
According to the second aspect of the present invention, the exhaust gas purification control means uses the excess air existing upstream of the intake throttle means as the air for regeneration of the DPF, and according to the situation of the exhaust gas downstream of the DPF, Since the amount of air is controlled, the DPF regeneration speed can be appropriately controlled.
Further, according to the third aspect of the present invention, the exhaust gas purification control means also controls the exhaust air-fuel ratio from the internal combustion engine in accordance with the state of the exhaust gas upstream of the NOx storage catalyst. The original function can be used, NOx can be reliably purified, and the exhaust gas performance can be improved.
[0045]
According to the fourth aspect of the present invention, the control of the amount of secondary air by the exhaust gas purification control means and the control of the exhaust air-fuel ratio from the internal combustion engine are not affected by the EGR gas. Thus, the S purge of the NOx storage catalyst and the forced regeneration of the DPF can be performed simultaneously and appropriately.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an engine to which an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention is applied.
FIG. 2 is a flowchart of a simultaneous regeneration control in the exhaust gas purification device of FIG.
[Explanation of symbols]
Reference Signs List 1 internal combustion engine 2 cylinder 8 intake passage 10 ETV (intake throttle means)
14 Supercharger 20 Exhaust passage 22 NOx storage catalyst 23 DPF (filter)
24 EGR passage 30 Secondary air supply passage 36 Temperature sensor 38 Air-fuel ratio sensor 40 Temperature sensor 42 Air-fuel ratio sensor 44 ECU (electronic control unit)
46 Exhaust gas purification control unit (Exhaust gas purification control means)

Claims (4)

An intake passage and an exhaust passage communicating with a cylinder of the internal combustion engine,
A supercharger and intake throttle means provided in the intake passage;
A NOx storage catalyst provided in the exhaust passage, which stores NOx in exhaust gas during a lean operation and performs a rich operation to release and reduce the stored NOx;
A filter provided on the exhaust gas downstream side of the NOx storage catalyst to collect particulate matter in the exhaust gas;
A secondary air supply passage for introducing air for regeneration of the filter from an intake upstream side of the intake throttle means to an exhaust upstream side of the filter,
An exhaust gas purification apparatus for an internal combustion engine, comprising: exhaust gas purification control means for controlling the amount of air in the secondary air supply passage. The exhaust gas purification device for an internal combustion engine according to claim 1, wherein a temperature sensor or an air-fuel ratio sensor for controlling the amount of air is provided downstream of the filter. The exhaust gas purification control means further controls an air-fuel ratio in the cylinder, and a temperature sensor or an air-fuel ratio sensor is provided on an exhaust gas upstream side of the NOx storage catalyst. An exhaust gas purifying apparatus for an internal combustion engine according to claim 1. The internal combustion engine includes an EGR passage that communicates the intake passage and the exhaust passage, and the exhaust gas purification control unit releases the NOx stored in the NOx storage catalyst and the S component attached to the NOx storage catalyst. The exhaust gas purifying apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein, when the particulate matter trapped in the filter is incinerated and removed, exhaust gas recirculation through the EGR passage is suppressed.

Images