JP2002242732A - Exhaust emission control device for internal combustion engine - Google Patents

Exhaust emission control device for internal combustion engine

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Publication number
JP2002242732A
JP2002242732A JP2001044063A JP2001044063A JP2002242732A JP 2002242732 A JP2002242732 A JP 2002242732A JP 2001044063 A JP2001044063 A JP 2001044063A JP 2001044063 A JP2001044063 A JP 2001044063A JP 2002242732 A JP2002242732 A JP 2002242732A
Authority
JP
Japan
Prior art keywords
injection amount
expansion stroke
exhaust
exhaust gas
main injection
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2001044063A
Other languages
Japanese (ja)
Inventor
Keiji Kawamoto
桂二 河本
Original Assignee
Nissan Motor Co Ltd
日産自動車株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd, 日産自動車株式会社 filed Critical Nissan Motor Co Ltd
Priority to JP2001044063A priority Critical patent/JP2002242732A/en
Publication of JP2002242732A publication Critical patent/JP2002242732A/en
Pending legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00Electrical control of exhaust gas treating apparatus
    • F01N9/002Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/103Oxidation catalysts for HC and CO only
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/02Circuit arrangements for generating control signals
    • F02D41/021Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/029Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a particulate filter
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/30Controlling fuel injection
    • F02D41/38Controlling fuel injection of the high pressure type
    • F02D41/40Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402Multiple injections
    • F02D41/405Multiple injections with post injections
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2240/00Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/36Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being an exhaust flap
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2430/00Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
    • F01N2430/08Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics by modifying ignition or injection timing
    • F01N2430/085Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics by modifying ignition or injection timing at least a part of the injection taking place during expansion or exhaust stroke
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/06Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02BINTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B37/00Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D2200/00Input parameters for engine control
    • F02D2200/02Input parameters for engine control the parameters being related to the engine
    • F02D2200/08Exhaust gas treatment apparatus parameters
    • F02D2200/0812Particle filter loading
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/02Circuit arrangements for generating control signals
    • F02D41/14Introducing closed-loop corrections
    • F02D41/1438Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1446Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/40Engine management systems

Abstract

(57) [Problem] To regenerate a filter for trapping fine particles in exhaust gas by controlling the exhaust gas temperature to a target temperature in a short time without being limited by an operation state. A main injection is provided in an exhaust passage, the main injection injecting fuel near a top dead center at the time of regeneration of the particulate collection means, and the main injection. In an exhaust gas purifying apparatus for an internal combustion engine that performs an expansion stroke injection for injecting fuel in a later expansion stroke, an expansion stroke injection amount Qp is set at a regeneration time of the filter 11 based on an operation state of the engine. The main injection amount Qm is reduced and corrected according to Qp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for increasing the temperature of exhaust gas of an internal combustion engine to regenerate a means for collecting particulates in the exhaust gas.

[0002]

2. Description of the Related Art In order to prevent exhaust particulates (particulates) emitted from an internal combustion engine, especially a diesel engine, from being released into the atmosphere, a filter made of ceramic or the like is provided in an exhaust passage, and the exhaust gas passing through the filter is provided. An exhaust gas purifying device that collects particulates is known.

[0003] In this type of exhaust gas purifying apparatus, since the exhaust gas pressure loss increases due to the accumulation of particulates on the filter and the engine performance deteriorates, the particulates collected by the filter are periodically burned to remove the particulates. Need to play. However, in diesel engines, except in the high-rotation, high-load region near full load, the exhaust gas temperature is lower than the combustible temperature of the particulates, and the particulates do not ignite spontaneously, so a filter regeneration operation using some auxiliary means is necessary. It becomes.

An example of such a filter regeneration operation is disclosed in Japanese Patent Application Laid-Open No. 2000-179326. This engine comprises a fuel injection means for performing a main fuel injection, an expansion stroke injection for injecting fuel during an expansion stroke after the main fuel injection in order to raise exhaust gas temperature, and an engine using the expansion stroke injection. By suppressing the increase in output (torque) by increasing the exhaust pressure loss due to the operation of the exhaust throttle, the exhaust gas temperature is controlled to the target temperature in a short time while suppressing the torque fluctuation, and the filter regeneration process is completed. Things.

[0005]

However, in the above-mentioned prior art, the exhaust gas flow rate is small, and in a low-rotation low-load region where a loss increase due to an exhaust throttle operation (ie, a torque fluctuation suppressing effect due to an increase in exhaust pressure loss) cannot be expected. However, there is a problem that the expansion stroke injection amount cannot be set large and the exhaust gas temperature cannot be raised to the target temperature (filter regeneration processing).

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to control the exhaust gas temperature to a target temperature in a short time without being limited to an operating state, and to perform a filter regeneration process. I do.

[0007]

According to a first aspect of the present invention, there is provided a fine particle collecting means disposed in an exhaust passage for collecting fine particles in exhaust gas, and the timing of regeneration of the fine particle collecting means is provided. In an exhaust gas purification apparatus for an internal combustion engine that performs main injection for injecting fuel near the top dead center and expansion stroke injection for injecting fuel in an expansion stroke after the main injection, the main injection amount is determined based on the operating state of the engine. A main injection amount setting means for setting, an expansion stroke injection amount setting means for setting an expansion stroke injection amount based on an operating state of the engine at a regeneration timing, and the main injection according to the expansion stroke injection amount at a regeneration timing. And a regeneration timing main injection amount correction means for reducing and correcting the amount.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the regeneration timing main injection amount correction means reduces the main injection amount as the expansion stroke injection amount increases. In the invention according to claim 3, in the invention according to claim 2, the regeneration timing main injection amount correction means sets the main injection amount to be smaller than the expansion stroke injection amount when the engine operating state is in a low rotation and low load region. It is characterized by doing.

According to a fourth aspect of the present invention, in the first aspect of the invention, there is provided an expansion stroke injection timing setting means for setting an expansion stroke injection timing based on the expansion stroke injection amount. It is characterized by having. Claim 5
In the invention according to any one of claims 1 to 4, at least one of an intake throttle valve for adjusting an intake flow rate and an exhaust throttle valve for adjusting an exhaust flow rate is closed during the regeneration timing. The throttle valve control means to be operated, and the throttle prohibition means for prohibiting the valve closing operation by the throttle valve control means when the operation state of the engine is in a low rotation and low load region are provided.

The invention according to claim 6 is the invention according to any one of claims 1 to 5, further comprising exhaust temperature detecting means for detecting exhaust temperature, and the exhaust temperature becomes the first target temperature. After the expansion stroke injection amount is set as described above, after the exhaust gas temperature reaches the first target temperature, the expansion stroke injection amount is reduced to reach the second target temperature lower than the first target temperature. It is characterized by controlling.

According to a seventh aspect of the present invention, in the first aspect of the present invention, there is provided an oxidation catalyst disposed in an exhaust passage, and a catalyst activity for determining an activation state of the oxidation catalyst. State determination means, when the load on the engine is reduced during the regeneration time, when the oxidation catalyst is activated, the expansion stroke injection timing is delayed, while when the oxidation catalyst is inactive, The expansion stroke injection amount is controlled to be small.

[0012]

According to the first aspect of the present invention, the exhaust gas temperature is increased by performing the expansion stroke injection to burn the fine particles during the regeneration time of the fine particle collecting means, thereby regenerating the fine particle collecting means. On the other hand, since the fuel amount of the main injection is reduced and corrected in accordance with the expansion stroke injection amount, it is possible to offset the torque generated by the expansion stroke injection by the torque reduction caused by the reduction of the fuel injected by the main injection. Therefore, it is possible to increase the exhaust gas temperature in a short time while suppressing the fluctuation of the torque.

As a result, including the case of low rotation and low load,
The regeneration processing of the particulate collection means can be performed in a short time without being limited by the operating state of the engine. Further, since the torque fluctuation is suppressed only by reducing the main injection amount, the fuel consumption and the exhaust purification performance do not need to be deteriorated. According to the second aspect of the present invention, the torque generated by the expansion stroke injection increases with an increase in the expansion stroke injection amount. However, the larger the expansion stroke injection amount, the smaller the main injection amount. The increase can be surely offset by the decrease in torque due to the decrease in fuel injected by the main injection, thereby suppressing torque fluctuation.

According to the third aspect of the invention, in the low-rotation, low-load region, the main injection amount is made smaller than the expansion stroke injection amount, so that it is possible to cope with a demand for a considerably large expansion stroke injection amount. By simply performing the expansion stroke injection, the low exhaust gas temperature (about 200 ° C. during normal operation) can be raised to a temperature (for example, 650 ° C.) at which ignition of exhaust particulates (particulates) starts.

Further, in the conventional exhaust throttle, a sufficient torque reduction effect cannot be obtained at a low rotation speed and a low load. However, a sufficient torque reduction can be achieved by reducing the main injection amount. According to the invention of claim 4, a part of the fuel injected by the expansion stroke injection changes to torque, but the rate of change to torque increases as the injection timing approaches the top dead center. Is increased and the torque tends to increase, the injection timing is retarded to reduce the rate of change to torque and reduce the contribution to torque fluctuation.

According to the fifth aspect of the invention, for example, when it is time to regenerate the particulate trapping means (filter) in the middle rotation and middle load region, the air is drawn into the cylinder by using the intake throttle together. Suppress the increase of low temperature fresh air flow,
The exhaust temperature can be raised effectively. For this reason, the injection amount of the expansion stroke can be set smaller than in the case where the intake throttle is not performed, so that the filter can be regenerated while minimizing the deterioration of fuel economy. In particular, when performing EGR for recirculating a part of the exhaust gas to the intake system on the downstream side of the intake throttle,
A large amount of high-temperature exhaust gas can be recirculated to the intake side, and the exhaust gas temperature can be raised more efficiently.

Further, by using an exhaust throttle at the time of filter regeneration, the internal EGR amount can be increased to increase the exhaust temperature, and the exhaust loss can be increased.
It is possible to more reliably suppress the torque fluctuation caused by the expansion stroke injection. On the other hand, in the low-rotation low-load region where the intake and exhaust volumes are small, the effect of performing intake and exhaust throttling is small, and in addition, the throttling operation reduces the amount of oxygen in the exhaust and reduces the burning speed of the particulates. Therefore, the restricting operation is prohibited, the burning speed of the particulates is maintained, and the filter can be regenerated in a short time.

According to the sixth aspect of the invention, in order to burn the particulates, it is necessary to first raise the exhaust gas temperature to the first target temperature at which the ignition of the particulates starts. The injection amount of the expansion stroke is set so that the target temperature is obtained. However, once the ignition occurs, the particulates burn due to the self-heating effect even if the exhaust gas temperature falls below the first target temperature. The expansion stroke injection amount is controlled so that the second target temperature can be maintained. As a result, the amount of fuel injected at the time of filter regeneration can be minimized, and deterioration of fuel efficiency and emission of incomplete combustion components such as HC and CO during filter regeneration can be suppressed.

According to the invention of claim 7, when the load on the engine is reduced and the torque needs to be reduced during the regeneration of the filter, the control method is selected according to the activation state of the oxidation catalyst. The filter can be regenerated as much as possible while suppressing the discharge of incomplete fuel components such as HC and CO.

That is, when the oxidation catalyst is in the activated state, the torque can be reduced while maintaining the exhaust gas temperature and performing the filter regeneration simply by delaying the expansion stroke injection timing. In this case, since the oxidation catalyst is in the activated state, the emission of HC is not deteriorated. On the other hand, when the oxidation catalyst is inactive, the expansion stroke injection timing cannot be retarded due to deterioration of HC emission. Therefore, the torque is reduced by reducing the expansion stroke injection amount. It should be noted that the torque should be reduced by reducing the main injection amount. However, especially in a diesel engine, the expansion stroke injection amount at the time of filter regeneration is considerably large (that is, the main injection amount is considerably small). ), The torque is reduced by reducing the expansion stroke injection amount, and the emission of HC is also suppressed.

Before the activation of the oxidation catalyst, H
If the engine is equipped with an exhaust purification catalyst that adsorbs C, regardless of whether the oxidation catalyst is in an activated state or an inactive state, the exhaust gas temperature can be maintained by retarding the expansion stroke injection timing. Thus, the torque can be reduced while performing the filter regeneration.

[0022]

Embodiments of the present invention will be described below. FIG. 1 shows a diesel engine to which the present invention is applied.
Shown in In FIG. 1, a diesel engine 1 pressurizes a fuel with a supply pump (not shown) and supplies the fuel to a common rail 2 to make the inside of the common rail 2 high pressure.
Electromagnetic fuel injection valve (injector) connected to it
A common rail type fuel injection system that injects fuel from 3 is adopted.

The injector 3 is operated by a needle valve (not shown) which moves up and down due to a fuel pressure balance by opening and closing an internal electromagnetic valve (not shown) in response to a signal from an engine control unit (ECU) 20. Inject and supply an amount of fuel according to the state. Further, the engine 1 is provided with a turbocharger 4, an intake passage 5 is connected to an intake outlet of the turbocharger 4, and an exhaust passage 6 is connected to an exhaust outlet of the turbocharger 4.

The intake passage 5 is provided with an intercooler 7 for cooling the intake air supercharged by the turbocharger 4, a collector 8, and an intake throttle valve 9 for adjusting the intake flow rate.
Then, the cooled intake air whose flow rate is reduced is collected by the collector 9.
Through the cylinder. The exhaust passage 6 is provided with an exhaust throttle valve 10 for adjusting an exhaust flow rate, an oxidation catalyst 11, a filter 12 for collecting exhaust particulates, and an exhaust temperature sensor 13 for detecting the temperature of exhaust gas flowing into the filter 12. I have.

The ECU 20 determines a fuel injection pressure, a fuel injection timing, a fuel injection pressure, based on various signals 21 indicating operating states such as an input engine speed, an accelerator opening signal, and a discharge temperature signal.
A control amount such as a fuel injection amount and an opening degree of the intake throttle valve 8 is calculated and a control signal 22 is output to control the injector 3, the intake throttle valve 9, the exhaust throttle valve 10, and the like. The ECU 20
Detects the output from a pressure sensor (not shown) disposed upstream and downstream of the filter 11, estimates the amount of particulate accumulated on the filter 11 based on the differential pressure, and determines the regeneration time of the filter 11. At the same time, the completion of regeneration of the filter 11 is determined by estimating the combustion state of the particulates (the state of reduction in the amount of particulates). The regeneration timing of the filter 11 is determined based on the operation state and the operation time. The completion of regeneration of the filter 11 may be determined based on the curated combustion time.

Next, filter regeneration control (first embodiment) by the ECU 20 will be described with reference to the flowchart shown in FIG. Step 1 (referred to as S1 in the figure; the same applies hereinafter)
Then, the engine rotation speed N detected by each sensor
e, the accelerator opening Acc and the exhaust temperature Texh are read.
In step 2, the required fuel injection amount Q is set based on the engine speed Ne and the accelerator opening Acc. Here, the required injection amount Q is a fuel injection amount that realizes the torque required by the driver.

In step 3, it is determined whether or not it is time to regenerate the filter. If it is not the regeneration time, the routine proceeds to step 13, where the required injection amount Q is set to the fuel injection amount (main injection amount) Qm by the main injection (main injection). On the other hand, if it is the reproduction time, the process proceeds to step 4. In step 4, the opening degree (throttle opening degree) Ath of the intake throttle valve 8 is set.

The setting of the intake throttle valve opening Ath is shown in FIG.
Is performed based on the required injection amount Q and the engine speed Ne by referring to a map as shown in FIG. Here, as shown in FIG. 3, in the low-rotation low-load region where the intake air amount is small, the effect of performing the intake throttling is small, and in addition, the amount of oxygen in the exhaust gas is reduced by the throttling operation, so that the particulate combustion is performed. Since the speed decreases, the intake throttle valve opening Ath is set to 0%.

In step 5, the exhaust temperature Texh and the first
Compare with the target temperature T1. Here, the first target temperature T1
Is the temperature at which ignition of the particulates deposited on the filter starts, which is 650 ° C. in the present embodiment. If the exhaust temperature Texh is equal to or higher than the first target temperature, step 6
Then, the FLAG is switched from 0 (initial value) to 1 and then the process proceeds to step 7. On the other hand, when the exhaust temperature Texh is the first
If the temperature is lower than the target temperature T1, the process proceeds to step 7 with FLAG = 0.

In step 7, it is determined whether or not FLAG is 0. When FLAG = 0, that is, when the exhaust gas temperature Texh has not reached the first target temperature T1,
Proceed to step 8. In step 8, the exhaust gas temperature Texh
Stroke amount (post-injection amount) Qp1 and main injection amount (main-injection amount) such that is increased to the first target temperature T1.
Set Qm.

Here, the post injection quantity Qp1 is set by referring to a map as shown in FIG. 4, and is set so as to increase as the rotation speed decreases and the load decreases (that is, the required injection quantity Q decreases). Is done. On the other hand, the main injection amount Qm
Is set based on the engine speed Ne and the required injection amount Q by referring to the map shown in FIG. The main injection amount Qm is set by reducing the required injection amount Q in accordance with the post injection amount Qp1, and as shown in FIG. 5, on the low rotation and low load side (that is, the post injection amount Qp1). Is increased).

In this embodiment, as shown in FIG. 6, the main injection amount Qm is set to be smaller than the post injection amount Qp1 in the low rotation and low load region. Returning to step 7, if FLAG = 1, the exhaust gas temperature T
Since 1 has already reached the first target temperature T1, the process proceeds to step 9. In step 9, the post injection amount is controlled to calculate the post injection amount Qp2 at which the exhaust gas temperature Texh maintains the second target temperature T2, and the main injection amount Qm is set.

Specifically, as shown in equation (1), the second
The previous post injection amount Qp (OLD) is corrected according to the deviation of the exhaust temperature Texh from the target temperature T2 to calculate the current post injection amount Qp2. Qp2 = Qp (OLD) + (T2−Texh) / T2 × ΔQ (1) where ΔQ is a predetermined injection amount step size.

Here, the second target temperature T2 is a temperature at which the burning of the ignited particulates can be maintained, and is 450 ° C. in the present embodiment. Also, the main injection amount Q
m is set with reference to the map (FIG. 5). However,
The main injection amount Qm may be increased and set in accordance with the decrease in the calculated post injection amount Qp2.

In step 10, the post injection timing ITpost is set based on the post injection amount Qp (Qp1 or Qp2) with reference to the table shown in FIG. Here, as shown in FIG. 7, the post-injection timing ITpost is retarded as the post-injection amount Qp increases, thereby suppressing fluctuations in the engine output (torque). Normally, the main injection timing ITmain is set to about 0 to 10 ° after the top dead center, and the post injection timing ITpost is set to 30 ° or more after the top dead center.

Then, the main injection amount Qm, the post injection amount Qp, and the post injection timing ITp set as described above are set.
By injecting fuel by ost, the exhaust gas temperature is controlled to the target temperature and the filter regeneration processing is performed in a short time. In step 11, it is determined whether the regeneration of the filter has been completed, that is, whether the combustion of the particulates accumulated on the filter has been completed. If the filter regeneration has been completed, the process proceeds to step 12, where the post-injection and intake throttle settings are released and initialized (FLAG = 0).

If the filter regeneration has not been completed, the flow returns to step 4 to perform the filter regeneration process again. As described above, when performing post-injection to increase the exhaust gas temperature, torque fluctuation can be suppressed by reducing and setting the main injection amount according to the post amount. Therefore, the filter can be regenerated by controlling the exhaust gas temperature to the target exhaust temperature in a short time without being limited by the operation state.

Particularly, in the low rotation speed and low load region, the post injection amount Qp is set to be larger than the main injection amount Qm, so that the temperature required for the filter regeneration can be raised in a short time, and the intake throttle can be adjusted. By prohibiting, it is possible to prevent the decrease in the amount of oxygen in the exhaust gas, maintain the particulate combustion speed, and complete the filter regeneration process in a short time.

Further, after the exhaust gas temperature is raised to the ignition start temperature of the particulates, the exhaust gas temperature is controlled to the exhaust gas temperature at which the combustion of the particulates can be maintained. Can be suppressed. In the above-described embodiment, the intake throttle is performed in the middle rotation and middle load range. However, the exhaust throttle may be performed instead of the intake throttle, or the intake throttle and the exhaust throttle may be used in combination. You may. These also make it possible to efficiently perform the filter regeneration in the medium rotation and medium load region while suppressing the torque fluctuation, and to prohibit the throttle operation in the low rotation and low load region to reduce the amount of oxygen in the exhaust gas. A decrease in the burning rate of the particulates due to the decrease can be prevented.

Next, control when the load on the engine is reduced during filter regeneration will be described with reference to the flowchart shown in FIG. Steps 21 to 23 are the same as steps 1 to 3 of the first embodiment, and include the engine speed Ne, the accelerator opening Acc, and the exhaust gas temperature T.
Exh is read, the required fuel injection amount Q is set, and it is determined whether or not it is the filter regeneration time.

If it is not the filter regeneration time, step 3
0, the required injection amount Q is changed to the main injection amount Q by the main injection.
m. On the other hand, if it is the regeneration time, the routine proceeds to step 24, where the main injection amount Qm is set with reference to FIG. 5, the post injection amount Qp is set with reference to FIG. 4, and the post injection timing ITpost is set with reference to FIG.

In step 25, the post injection amount Qp and the main injection amount Qm are compared. If the post injection amount Qp is larger than the main injection amount Qm, the process proceeds to step 26, and if the post injection amount Qp is equal to or less than the main injection amount Qm, the present control ends. In step 26, the load state of the engine is determined. If the engine load has decreased (for example, if the range has been changed from the D range to the N range or if the air conditioner has been turned off), the process proceeds to step 27, and if the engine load has not decreased, this control ends.

In step 27, it is determined whether or not the exhaust gas temperature Texh exceeds the oxidation catalyst activation temperature TCA. If the exhaust temperature Texh exceeds the oxidation catalyst activation temperature TCA, that is, if the catalyst is activated, the process proceeds to step 28, where the post injection timing ITpost
Retard. The exhaust temperature Texh is equal to the oxidation catalyst temperature TCA
In the following cases, the process proceeds to step 29, where the post injection amount Qp
To lose weight.

As described above, when the load on the engine is reduced during the regeneration of the filter and the torque is reduced, the control method is selected according to the activation state of the oxidation catalyst so that the HC and C are controlled.
The filter can be regenerated as much as possible while suppressing emission of incomplete combustion components such as O.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a diesel engine to which the present invention is applied.

FIG. 2 is a flowchart showing filter regeneration control according to the present invention.

FIG. 3 is a diagram showing a map used when setting an intake throttle valve opening degree Ath.

FIG. 4 is a diagram showing a map used when setting a post injection amount Qp1.

FIG. 5 is a diagram showing a map used when setting a main injection amount Qm1 when performing post injection.

FIG. 6 is a diagram showing a relationship between a post injection amount Qp and a main injection amount Qm.

FIG. 7 is a diagram showing a map used when setting a post injection timing ITpost.

FIG. 8 is a flowchart showing control when the load on the engine is reduced during filter regeneration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diesel engine 2 ... Common rail 3 ... Injector 9 ... Intake throttle valve 10 ... Exhaust throttle valve 11 ... Oxidation catalyst 12 ... Filter 13 ... Exhaust temperature sensor 20 ... ECU

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) F01N 3/02 321 F01N 3/18 ZABB 4D048 3/18 ZAB 3/24 E 4D058 3/24 R N 3 / 36 B 3/36 F02D 9/02 R F02D 9/02 351M 351 9/04 C 9/04 E 41/20 385 41/20 385 43/00 301H 43/00 301 301J 301K 301T 301W 45/00 301A 45 / 00 301 314T 314 314Z 322B 322 B01D 46/42 B // B01D 46/42 46/46 46/46 53/36 103C F term (reference) 3G065 AA01 AA03 AA09 CA12 DA04 EA09 EA12 FA14 GA08 GA10 GA31 GA37 GA46 HA06 KA02 3 AA01 AA03 AA04 BA05 BA08 BA09 BA13 BA15 BA19 BA20 BA24 DA10 DA11 DA27 EA11 EB01 EB08 EC03 FA10 FA27 FA33 3G090 AA01 CA01 C A02 CA03 DA04 DA12 DA18 DA20 EA01 EA02 EA04 EA05 EA07 3G091 AA02 AA10 AA11 AA18 AA28 AB02 AB13 BA00 BA15 BA19 BA32 CA13 CB02 CB03 CB07 CB08 DA01 DA02 DB06 DB07 DB10 EA01 EA07 HA03 HA03 HA03 HA03 HA03 HA04 JA24 JA26 JB09 LA03 LB11 MA01 MA11 MA18 MA19 MA20 MA26 NA06 NA07 NA08 NB18 NC02 NE01 NE06 PD11B PD11Z PE01B PE01Z PF03B PF03Z 4D048 AA14 AB01 CC51 CD05 DA01 DA02 DA06 DA20 4D058 JA32 JB06 MA42 MA44 TA52 MA08

Claims (7)

    [Claims]
  1. And a main injection means for injecting fuel near a top dead center at a time of regeneration of the fine particle collecting means, the main injection means being provided in an exhaust passage for collecting fine particles in the exhaust gas. In an exhaust gas purification apparatus for an internal combustion engine that performs an expansion stroke injection for injecting fuel in an expansion stroke after injection, a main injection amount setting means for setting a main injection amount based on an operation state of the engine, Expansion stroke injection amount setting means for setting an expansion stroke injection amount based on an operation state; and regeneration timing main injection amount correction means for correcting a reduction in the main injection amount according to the expansion stroke injection amount at a regeneration timing. An exhaust gas purification device for an internal combustion engine, comprising:
  2. 2. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein said regeneration timing main injection amount correction means decreases the main injection amount as the expansion stroke injection amount increases.
  3. 3. The regenerative timing main injection amount correction means makes the main injection amount smaller than the expansion stroke injection amount when the engine operating state is in a low rotation and low load region. Exhaust purification device for internal combustion engine.
  4. 4. An internal combustion engine according to claim 1, further comprising an expansion stroke injection timing setting means for setting an expansion stroke injection timing based on the expansion stroke injection amount. Exhaust purification equipment.
  5. 5. A throttle valve control means for closing at least one of an intake throttle valve for adjusting an intake flow rate and an exhaust throttle valve for adjusting an exhaust flow rate during the regeneration timing; The exhaust purification device for an internal combustion engine according to any one of claims 1 to 4, further comprising a throttle prohibition unit that prohibits a valve closing operation by the throttle valve control unit in a region.
  6. 6. An exhaust temperature detecting means for detecting an exhaust gas temperature, wherein the expansion stroke injection amount is set so that the exhaust gas temperature becomes a first target temperature, and after the exhaust gas temperature reaches the first target temperature. The internal combustion engine according to any one of claims 1 to 5, wherein the controller controls the injection amount to be reduced to a second target temperature lower than the first target temperature. Engine exhaust purification device.
  7. 7. An oxidation catalyst provided in an exhaust passage, and catalyst activation state determination means for determining an activation state of the oxidation catalyst, wherein the oxidation catalyst is activated when a load on the engine is reduced at the regeneration time. 7. When the fuel cell is activated, the expansion stroke injection timing is delayed, while when the oxidation catalyst is inactive, control is performed to reduce the expansion stroke injection amount. A haiku purification device for an internal combustion engine according to any one of the above.
JP2001044063A 2001-02-20 2001-02-20 Exhaust emission control device for internal combustion engine Pending JP2002242732A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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Application Number Priority Date Filing Date Title
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004106703A1 (en) * 2003-05-28 2004-12-09 Isuzu Motors Limited Exhaust gas cleaning system
JP2005133596A (en) * 2003-10-29 2005-05-26 Toyota Motor Corp Method for raising temperature of exhaust emission control catalyst for internal combustion engine
JP2006505738A (en) * 2002-11-05 2006-02-16 ボルボ ラストバグナー アーベー Purification method for particulate removing device and vehicle using the method
WO2006075787A1 (en) * 2005-01-13 2006-07-20 Toyota Jidosha Kabushiki Kaisha Internal combustion engine exhaust emission control system
JP2011052641A (en) * 2009-09-03 2011-03-17 Denso Corp Device for controlling exhaust emission for internal combustion engine
JP2013096359A (en) * 2011-11-04 2013-05-20 Mitsubishi Motors Corp Fuel injection control device of internal combustion engine
JP2015117650A (en) * 2013-12-19 2015-06-25 マツダ株式会社 Control device of direct injection engine

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006505738A (en) * 2002-11-05 2006-02-16 ボルボ ラストバグナー アーベー Purification method for particulate removing device and vehicle using the method
WO2004106703A1 (en) * 2003-05-28 2004-12-09 Isuzu Motors Limited Exhaust gas cleaning system
US7337608B2 (en) 2003-05-28 2008-03-04 Isuzu Motors Limited Exhaust gas cleaning system
CN100427739C (en) * 2003-05-28 2008-10-22 五十铃自动车株式会社 Exhaust gas cleaning system
JP2005133596A (en) * 2003-10-29 2005-05-26 Toyota Motor Corp Method for raising temperature of exhaust emission control catalyst for internal combustion engine
JP4556417B2 (en) * 2003-10-29 2010-10-06 トヨタ自動車株式会社 Method for raising the temperature of an exhaust purification catalyst for an internal combustion engine
WO2006075787A1 (en) * 2005-01-13 2006-07-20 Toyota Jidosha Kabushiki Kaisha Internal combustion engine exhaust emission control system
US7395660B2 (en) 2005-01-13 2008-07-08 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification system for an internal combustion engine
JP2011052641A (en) * 2009-09-03 2011-03-17 Denso Corp Device for controlling exhaust emission for internal combustion engine
JP2013096359A (en) * 2011-11-04 2013-05-20 Mitsubishi Motors Corp Fuel injection control device of internal combustion engine
JP2015117650A (en) * 2013-12-19 2015-06-25 マツダ株式会社 Control device of direct injection engine

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