US20140216017A1 - Control apparatus for internal combustion engine - Google Patents

Control apparatus for internal combustion engine Download PDF

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Publication number
US20140216017A1
US20140216017A1 US14/347,497 US201114347497A US2014216017A1 US 20140216017 A1 US20140216017 A1 US 20140216017A1 US 201114347497 A US201114347497 A US 201114347497A US 2014216017 A1 US2014216017 A1 US 2014216017A1
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Prior art keywords
internal combustion
based regeneration
combustion engine
threshold value
particulate filter
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US14/347,497
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English (en)
Inventor
Akira Shirai
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Toyota Motor Corp
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Toyota Motor Corp
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Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA reassignment TOYOTA JIDOSHA KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SHIRAI, AKIRA
Publication of US20140216017A1 publication Critical patent/US20140216017A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9495—Controlling the catalytic process
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F01N3/0231—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using special exhaust apparatus upstream of the filter for producing nitrogen dioxide, e.g. for continuous filter regeneration systems [CRT]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing 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
    • F02D41/0275—Introducing 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 NOx trap or adsorbent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/36—Control for minimising NOx emissions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing 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
    • F02D41/029—Introducing 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/06—Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor

Definitions

  • the present invention relates to a control apparatus for an internal combustion engine, and more particular to a control apparatus for an internal combustion engine that is suitable for controlling the internal combustion engine which includes, in an exhaust passage, a particulate filter for trapping particulate matter.
  • Patent Document 1 discloses a diesel engine which actively performs a method (hereinafter, referred to as “NO 2 -based regeneration) that uses the following oxidation reaction ((2C+2NO 2 ⁇ CO 2 +2NO) and/or (C+NO 2 ⁇ CO+NO)) using nitrogen dioxide (NO 2 ) to oxidizes and removes, using recirculated NOx, particulate matter (soot) trapped by a diesel particulate filter (DPF).
  • NO 2 -based regeneration uses the following oxidation reaction ((2C+2NO 2 ⁇ CO 2 +2NO) and/or (C+NO 2 ⁇ CO+NO)) using nitrogen dioxide (NO 2 ) to oxidizes and removes, using recirculated NOx, particulate matter (soot) trapped by a diesel particulate filter (DPF).
  • NO 2 -based regeneration uses the following oxidation reaction ((2C+2NO 2 ⁇ CO 2 +2NO) and/or (C+NO
  • O 2 -based regeneration As a method for oxidizing and removing particulate matter accumulated on a particulate filter, there is known a method (hereinafter, referred to as “O 2 -based regeneration”) that uses the following oxidation reaction ((C+O 2 ⁇ CO 2 ) and/or (2C+O 2 ⁇ 2CO)) to oxidize and remove, using oxygen (O 2 ), particulate matter trapped by the particulate filter, besides the NO 2 -based regeneration disclosed in Patent Document 1.
  • oxidation reaction (C+O 2 ⁇ CO 2 ) and/or (2C+O 2 ⁇ 2CO)
  • the NO 2 -based regeneration In order to efficiently perform the NO 2 -based regeneration during operation of an internal combustion engine, it is required, as compared to the time of the normal combustion, to increase the amount of NO 2 supplied to a particulate filter, and to increase the temperature of the particulate filter albeit to a lower extent compared to the time of the O 2 -based regeneration.
  • the NO 2 -based regeneration requires a longer time to regenerate the particulate filter as compared to the O 2 -based regeneration. It is therefore conceivable that when the NO 2 -based regeneration is actively performed without sufficient consideration with respect to the operating state at the time of performance of the NO 2 -based regeneration, the NO 2 -based regeneration may be performed over a long period of time. As a result, this comes down to problems, such as the deterioration of exhaust emission performance due to an increase in NOx emission and the deterioration of fuel efficiency due to execution of, for example, an additional fuel injection to increase the temperature of the particulate filter.
  • the present invention has been made to solve the problem as described above, and has its object to provide a control apparatus for an internal combustion engine which can ensure the opportunity in which the NO 2 -based regeneration is efficiently performed during operation while suppressing an increase in the amount of NOx emission and the deterioration of fuel efficiency as much as possible.
  • the present invention is a control apparatus for an internal combustion engine that includes: a particulate filter; NO 2 production means; NO 2 -based regeneration speed estimation means; operating state determination means; and control parameter change means.
  • the particulate filter is installed in an exhaust passage of the internal combustion engine and traps particulate filter.
  • NO 2 production means produces NO 2 in exhaust gas supplied to the particulate filter.
  • NO 2 -based regeneration speed estimation means estimates the speed of regeneration of the particulate filter using NO 2 (hereinafter, referred to as an “NO 2 -based regeneration speed”) during operation of the internal combustion engine.
  • Operating state determination means determines whether or not an operating state in which the NO 2 -based regeneration speed is higher than a predetermined threshold value is established during operation of the internal combustion engine.
  • Control parameter change means changes an engine control parameter so that when the operation state in which the NO 2 -based regeneration speed is higher than the threshold value is determined to be established by the operation state determination means, at least one of the amount of NO 2 supplied to the particulate filter and the temperature of the particulate filter is increased.
  • the engine control parameter can be changed so as to facilitate the NO 2 -based regeneration with selection of an operating state in which sufficient execution of NO 2 -based regeneration can be expected. Therefore, the period of performing the aforementioned change in the engine control parameter for facilitating the NO 2 -based regeneration can be prevented from becoming too long. This can ensure the opportunity in which the NO 2 -based regeneration is efficiently performed during the operation while suppressing an increase in the amount of NOx emission and the deterioration of fuel efficiency as much as possible.
  • the present invention may further include first control parameter change prohibition means for, even when the operation state in which the NO 2 -based regeneration speed is higher than the threshold value is established, prohibiting a change in the engine control parameter by the control parameter change means in a case in which an outside air temperature is lower than or equal to a predetermined value and/or an engine cooling water temperature is lower than or equal to a predetermined value.
  • the present invention may further include second control parameter change prohibition means for, even when the operation state in which the NO 2 -based regeneration speed is higher than the threshold value is established, prohibiting a change in the engine control parameter by the control parameter change means in a case in which torque control is performed so that a torque of the internal combustion engine is maintained.
  • the present invention may further include third control parameter change prohibition means for, even when the operation state in which the NO 2 -based regeneration speed is higher than the threshold value is established, prohibiting a change in the engine control parameter by the control parameter change means in a case in which a vehicle on which the internal combustion engine is mounted is traveling in an urban area.
  • the present invention may further include parameter change suspend means for suspending a change in the engine control parameter by the control parameter change means when the operation state in which the NO 2 -based regeneration speed is higher than the threshold value has stopped being established during a period in which the change in the engine control parameter is being performed by the control parameter change means.
  • the operating state determination means in the present invention may determine that the operating state in which the NO 2 -based regeneration speed is higher than the threshold value has been established when the temperature of the particulate filter is higher than a predetermined threshold value and the amount of accumulation of particulate matter in the particulate filter is larger than a predetermined threshold value and the amount of NO 2 flown into the particulate filter is larger than a predetermined threshold value.
  • FIG. 1 is a diagram for explaining a system configuration according to a first embodiment of the present invention
  • FIG. 2 is a flowchart of a routine that is executed in the first embodiment of the present invention
  • FIG. 3 is a block diagram that illustrates the outline of an NO 2 -based regeneration speed model
  • FIG. 4 is a chart for explaining the effect of control of the NO 2 -based regeneration according to the first embodiment of the present invention.
  • FIG. 1 is a diagram for explaining a system configuration according to a first embodiment of the present invention.
  • the system shown in FIG. 1 includes an internal combustion engine 10 .
  • the internal combustion engine 10 is a four-cycle diesel engine (compression ignition internal combustion engine) 10 and is mounted in a vehicle to work as its power source.
  • the internal combustion engine 10 of the present embodiment is of an in-line four cylinder type, the number and arrangement of cylinders in the internal combustion engine in the present invention are not limited to the foregoing.
  • a fuel injection valve 12 that directly injects fuel into the cylinder is installed in each cylinder of the internal combustion engine 10 .
  • the fuel injection valve 12 of each cylinder is connected to a shared common-rail (not illustrated in the drawings) to which a high pressure fuel which is pressurized by a supply pump (not illustrated in the drawings) is supplied. From this common-rail, the fuel is supplied to the fuel injection valve 12 of each cylinder.
  • Each cylinder is in communication with an intake passage 14 and an exhaust passage 16 .
  • An air cleaner 18 is provided in the vicinity of the inlet of the intake passage 14 of the internal combustion engine 10 .
  • An air flow meter 20 for detecting the amount of intake air is installed near the downstream of the air cleaner 18 in the intake passage 14 .
  • the air suctioned through the air cleaner 18 is compressed by a compressor 22 a of a turbo-supercharger 22 .
  • the turbo-supercharger 22 includes a turbine 22 b which is operated by exhaust energy of exhaust gas, and a compressor 22 a which is integrally coupled to the turbine 22 b is driven to rotate by the exhaust energy of the exhaust gas input to the turbine 22 b.
  • An intake throttle valve 24 is installed at a section on the downstream side of the compressor 22 a in the intake passage 14 .
  • the turbine 22 b of the turbo-supercharger 22 is installed at some point in the exhaust passage 16 .
  • a diesel oxidation catalyst (DOC) 26 and a diesel particulate filter (DPF) 28 are installed in series in the order from the upstream side of exhaust gas to purify the exhaust gas.
  • the DOC 26 has functions to not only oxidize and remove hydrocarbon (HC) and carbon monoxide (CO) but also to oxidize a part of nitrogen monoxide (NO) that is contained in the supplied exhaust gas to convert it into nitrogen dioxide (NO 2 ), under a condition in which oxygen (O 2 ) is present.
  • the DPF 28 has a function to trap particulate matter (PM) that is composed of soot and the like and that is contained in the exhaust gas.
  • PM particulate matter
  • the PM (specially, soot) trapped by the DPF 28 is oxidized and removed by execution of a regeneration process described later.
  • a temperature sensor 30 for detecting the temperature of the exhaust gas that is flown into the DOC 26 (DOC inlet gas temperature) is installed in the exhaust passage 16 on the upstream side of the DOC 26
  • a temperature sensor 32 for detecting the temperature of the exhaust gas that is flown into the DPF 28 (DPF inlet gas temperature) is installed in the exhaust passage 16 on the upstream side of the DPF 28 .
  • HPL 34 High Pressure Loop
  • the HPL 34 is configured to allow the exhaust passage 16 on the upstream side of the turbine 22 b to be communicated with the intake passage 14 located downstream side of the compressor 22 a.
  • an HPL-EGR valve 36 is disposed to adjust the amount of recirculated exhaust gas (EGR (Exhaust Gas Recirculation) gas) that flows back into the intake passage 14 through the HPL 34 .
  • EGR Exhaust Gas Recirculation
  • the system shown in FIG. 1 is further provided with a low-pressure exhaust gas recirculation passage (LPL: Low Pressure Loop) 38 .
  • the LPL 38 is configured to allow the exhaust passage 16 on the downstream side of the turbine 22 b and the downstream side of the DPF 28 to be communicated with the intake passage 14 on the upstream side of the compressor 22 a.
  • the EGR cooler 40 is of water-cooled type using an engine cooling water that cools the main body of the internal combustion engine 10 .
  • the engine cooling water that is heated by the EGR gas in the EGR cooler 40 is supplied to a heater (not illustrated in the drawings) of the vehicle on which the internal combustion engine 10 is mounted.
  • a crank angle sensor 46 for detecting a crank angle and an engine speed is installed in the vicinity of a crankshaft 44 .
  • a water temperature sensor 48 for detecting the temperature of the engine cooling water is installed in the internal combustion engine 10 .
  • the system of the present embodiment includes an ECU (Electronic Control Unit) 50 .
  • ECU Electronic Control Unit
  • various sensors for detecting the operating state of the internal combustion engine 10 such as the air flow meter 20 , the temperature sensors 30 and 32 , the crank angle sensor 46 , the water temperature sensor 48 and the like that are described above.
  • a vehicle speed sensor 52 for detecting the speed of the vehicle (not illustrated in the drawings) on which the internal combustion engine 10 is mounted
  • a shift position sensor 54 for detecting a shift position of a transmission (not illustrated in the drawings) that is combined with the internal combustion engine 10
  • an accelerator position sensor 56 for detecting the depression amount (accelerator position) of an accelerator pedal of the vehicle
  • an outside air temperature sensor 58 for detecting the outside air temperature.
  • various actuators for controlling the operation of the internal combustion engine 10 such as the fuel injection valve 12 , the intake throttle valve 24 , the HPL-EGR valve 36 , the LPL-EGR valve 42 and the like that are described above.
  • the ECU 50 controls the operating state of the internal combustion engine 10 by actuating each actuator on the basis of the output of each sensor and predetermined programs.
  • O 2 -based regeneration As methods of forcibly regenerating the aforementioned DPF 28 by oxidizing and removing the PM (soot) trapped by the DPF 28 , there are a method that is forcibly performed using O 2 (hereinafter, referred to as “O 2 -based regeneration”) and a method using NO 2 (hereinafter, referred to as “NO 2 -based regeneration”).
  • the soot (PM) is oxidized and removed using the following oxidation reaction ((C+O 2 ⁇ CO 2 ) and/or (2C+O 2 ⁇ 2CO)) by increasing the exhaust gas temperature by use of, for example, executing an after-injection after a main injection to forcibly increase the temperature (floor temperature) of the DPF 28 so as to be higher than or equal to a predetermined regeneration target temperature (for example, 600 degrees Celsius).
  • a predetermined regeneration target temperature for example, 600 degrees Celsius
  • soot (PM) is oxidized and removed using the following oxidization reaction of soot ((C+2NO 2 ⁇ CO 2 +2NO) and/or (C+NO 2 ⁇ CO+NO)) by increasing the amount of NO 2 supplied to the DPF 28 by use of adjustment of an engine control parameter (fuel injection parameter (such as fuel injection timing or pilot injection amount) or the amount of EGR gas) for increasing NOx (NO) discharged from the cylinders, and by increasing the temperature (floor temperature) of the DPF 28 so as to be higher than or equal to a predetermined temperature (about 300 to 400 degrees Celsius) albeit to a relatively lower extent compared to the time of the O 2 -based regeneration.
  • fuel injection parameter such as fuel injection timing or pilot injection amount
  • EGR gas the amount of EGR gas
  • the NO 2 -based regeneration In order to efficiently perform the NO 2 -based regeneration during operation of the internal combustion engine 10 , as already described, it is required, as compared to the time of the normal combustion, to increase the amount of NO 2 supplied to the DPF 28 , and to increase the temperature of the DPF 28 albeit to a lower extent compared to the time of the O 2 -based regeneration.
  • the NO 2 -based regeneration requires a longer time to regenerate the DPF 28 as compared to the O 2 -based regeneration. It is therefore conceivable that when the NO 2 -based regeneration is actively performed without sufficient consideration with respect to the operating state at the time of performance of the NO 2 -based regeneration, the NO 2 -based regeneration may be performed over a long period of time. As a result, this comes down to problems, such as the deterioration of exhaust emission performance due to an increase in NOx emission and the deterioration of fuel efficiency due to execution of, for example, an additional fuel injection to increase the temperature of the DPF 28 .
  • the present embodiment uses an NO 2 -based regeneration speed model described later with reference to FIG. 3 to determine whether or not an operating state in which the speed of NO 2 -based regeneration (hereafter, referred to as an “NO 2 -based regeneration speed”) is larger than a predetermined threshold value is established during operation of the internal combustion engine 10 .
  • an NO 2 -based regeneration mode is executed which facilitates NO 2 -based regeneration compared to the time of the normal combustion that uses an identical operating region (more specifically, which increases the amount of NO 2 supplied to the DPF 28 and raises the floor temperature of the DPF 28 ).
  • One example of the predetermined engine operation conditions subject to prohibition of NO 2 -based regeneration is the time of low-temperature when the outside air temperature and/or the engine cooling water temperature is lower than or equal to a predetermined value.
  • another example of the engine operation conditions is the time of execution of torque control to maintain the torque of the internal combustion engine 10 (for example, the time of idling operation or the time of cruise control at which the torque of the internal combustion engine 10 is made constant to maintain the vehicle speed).
  • the time of traveling in an urban area can be taken as another example of the engine operation conditions.
  • the execution of the NO 2 -based regeneration mode for facilitating the NO 2 -based regeneration is prohibited even if the NO 2 -based regeneration speed is larger than the aforementioned threshold value during operation of the internal combustion engine 10 , that is, even if the engine 10 is in an operating state in which the NO 2 -based regeneration can be sufficiently executed.
  • FIG. 2 is a flowchart that illustrates a control routine executed by the ECU 50 to implement control concerning the NO 2 -based regeneration according to the first embodiment of the present invention. It is assumed that the present routine is repeatedly executed for each predetermined control period.
  • step 100 it is determined whether or not the NO 2 -based regeneration speed is higher than a predetermined threshold value (step 100 ).
  • the threshold value in present step 100 is set in advance as a value for judging whether or not an operating state in which the NO 2 -based regeneration can be expected to be executed sufficiently (that is, in a short time) during operation of the internal combustion engine 10 is established (arrived).
  • FIG. 3 is a block diagram that illustrates the outline of an NO 2 -based regeneration speed model.
  • the NO 2 -based regeneration speed model shown in FIG. 3 is a model that calculates the NO 2 -based regeneration speed (the speed of regeneration of the DPF 28 , (that is, the speed of oxidation of soot (PM) that results from the effect of the NO 2 -based regeneration) on the basis of the floor temperature of the DPF 28 , the amount of soot accumulation in the DPF 28 , and the amount of NO 2 flown into the DPF 28 .
  • the NO 2 -based regeneration speed the speed of regeneration of the DPF 28 , (that is, the speed of oxidation of soot (PM) that results from the effect of the NO 2 -based regeneration) on the basis of the floor temperature of the DPF 28 , the amount of soot accumulation in the DPF 28 , and the amount of NO 2 flown into the DPF 28 .
  • a DPF floor temperature coefficient concerning the NO 2 -based regeneration speed is calculated on the basis of the present DPF floor temperature, using an one-dimensional map that defines the DPF floor temperature coefficient so as to increase with a rise in the DPF floor temperature.
  • the DPF floor temperature itself can be calculated, for example, on the basis of a DPF inlet gas temperature detected by the temperature sensor 32 or on the basis of the operating state of the internal combustion engine 10 (engine speed, and engine load (fuel injection amount)).
  • a soot accumulation amount coefficient concerning the NO 2 -based regeneration speed is calculated on the basis of the present soot accumulation amount, an using one-dimensional map that defines the soot accumulation amount coefficient so as to increase with an increase in the soot accumulation amount.
  • the soot accumulation amount itself can be estimated, for example, on the basis of an operation record of the internal combustion engine 10 (engine speed, torque, air-fuel ratio and the like) or the difference between pressures before and after the DPF (DPF differential pressure).
  • a DPF inflow NO 2 amount is calculated on the basis of the product of the rate of reaction (conversion rate) from NO to NO 2 as a result of the oxidation in the DOC 26 and the estimation amount of NO 2 in the exhaust gas discharged from the cylinders.
  • the aforementioned rate of reaction from NO to NO 2 increases with an increase in the exhaust gas flow rate, or with an increase in the DOC floor temperature.
  • the rate of reaction is calculated on the basis of the present exhaust gas flow rate and DOC floor temperature, using a two-dimensional map that defines the rate of reaction so as to increase with an increase in the exhaust gas flow rate and so as to increase with a rise in the DOC floor temperature.
  • the estimation amount of NOx in the exhaust gas discharged from the cylinders is based on the value of a two-dimensional map that defines the estimation amount of NOx in a relation with the engine speed NE and the fuel injection amount Q, and is calculated by multiplying the aforementioned value by each of predetermined environmental correction coefficients (correction coefficients based on the engine cooling water temperature, the outside air temperature and the atmospheric air pressure) and a predetermined EGR ratio correction coefficient.
  • predetermined environmental correction coefficients corrected coefficients based on the engine cooling water temperature, the outside air temperature and the atmospheric air pressure
  • a predetermined EGR ratio correction coefficient predetermined EGR ratio correction coefficient
  • the NO 2 -based regeneration speed is calculated as the product of the DPF floor temperature coefficient, the soot accumulation amount coefficient and the DPF inflow NO 2 amount that are calculated as described above. More specifically, the NO 2 -based regeneration speed is calculated as a value that becomes higher with each increase in these parameters, that is to say, the DPF floor temperature coefficient, the soot accumulation amount coefficient and the DPF inflow NO 2 amount.
  • a state in which the NO 2 -based regeneration speed is higher than the threshold value is a state in which: the DPF floor temperature is high than a predetermined threshold value; the soot accumulation amount is larger than a predetermined threshold value; and the DPF inflow NO 2 amount is larger than a predetermined threshold value.
  • the time of vehicle traveling when the internal combustion engine 10 is in a high-load state more specifically, such as the time of high-speed traveling, the time of uphill traveling, or the time of acceleration of the vehicle, corresponds to a concrete example of the state in which the NO 2 -based regeneration speed is higher than the threshold value.
  • step 100 if it is determined in step 100 that the NO 2 -based regeneration speed that is estimated by the NO 2 -based regeneration speed model is higher than the aforementioned threshold value, that is to say, if it can be judged that an operating state in which the NO 2 -based regeneration is sufficiently executed has been established (arrived) during operation of the internal combustion engine 10 , it is then determined whether or not an engine operation condition that does not require many trade-offs with respect to the execution of the NO 2 -based regeneration mode is met (step 102 ). Specifically, in present step 102 , it is judged whether or not the present operation condition does not correspond to any of the predetermined engine operation conditions subject to prohibition of NO 2 -based regeneration that are already described.
  • step 102 it is judged: whether or not the time of low-temperature subject to prohibition of NO 2 -based regeneration has not come on the basis of the outside air temperature and the engine cooling water temperature; whether or not the time of execution of the torque control (the time of idling operation or the time of cruise control) has not come; and whether or not the time of traveling in an urban area has not come on the basis of the vehicle speed (or, for example, the behavior of exhaust gas temperature).
  • present step 102 determination as to whether or not an operating state suitable for execution of the NO 2 -based regeneration mode is established is broadly executed on the basis of the combination of parameters such as the DOC inlet gas temperature, the DPF inlet gas temperature, the vehicle speed, the fuel injection amount, the engine speed and the gear positions of the transmission.
  • the NO 2 -based regeneration mode is an operation mode for facilitating the NO 2 -based regeneration (for increasing the NO 2 -based regeneration speed) compared to the time of the normal combustion that uses an identical operating region (more specifically, an operation mode for increasing the amount of NO 2 supplied to the DPF 28 and for raising the floor temperature of the DPF 28 ).
  • the NO 2 -based regeneration mode can be implemented by, for example, changing the engine control parameters compared to that at the time of the normal combustion as follows. More specifically, when transitioning to the NO 2 -based regeneration mode, for example, a control map for a predetermined engine control parameter (EGR gas amount or fuel injection parameter) is switched from a control map used at the time of the normal combustion mode. In detail, by switching such control map, the amount of EGR gas using the LPL-EGR and/or HPL-EGR is decreased in order to increase the amount of NOx discharged from the cylinders (as one example, the introduction of the EGR gas using the LPL-EGR and/or HPL-EGR is stopped).
  • a control map for a predetermined engine control parameter EGR gas amount or fuel injection parameter
  • the control map is switched to optimize the fuel injection parameter so that a crank angle position at which combustion is generated is moved to the retard side compared to that at the time of the normal combustion.
  • the fuel injection timing is retarded with respect to the value at the time of the normal combustion, and the amount of pilot injection is increased to suppress the deterioration of combustion in association therewith.
  • the control map is switched so that an after-injection is executed.
  • feedback control for at least one of the DPF floor temperature, the DOC floor temperature and the NOx emission amount may be executed in order to maintain high the NO 2 -based regeneration speed.
  • Such feedback control can, for example, be executed by adjusting the exhaust gas temperature with a change in the amount of the after-injection and the fuel injection timing (further, by adjusting the NOx emission amount).
  • a combustion model is installed in an ECU of an internal combustion engine and the operation of the internal combustion engine can be controlled on the basis of the combustion model, the following method may be used.
  • the combination of the engine control parameters that is capable of obtaining the optimum exhaust gas temperature may be fixed using the aforementioned combustion model.
  • the relation of each change amount of the fuel efficiency, the NOx emission amount and the exhaust gas temperature with respect to a change in the engine control parameters may be installed in advance as a map or a curve for every engine control parameter, in each operating region of the internal combustion engine. Based on such relation of the map or the like, a control value of each engine control parameter at the time of the NO 2 -based regeneration mode may be fixed.
  • step 106 if the aforementioned determination of step 100 or 102 is negative, the NO 2 -based regeneration mode is not executed (is prohibited), or if the aforementioned determination of step 100 or 102 has become negative during execution of the NO 2 -based regeneration mode, the NO 2 -based regeneration mode is suspended (step 106 ).
  • the NO 2 -based regeneration mode for facilitating the NO 2 -based regeneration is executed.
  • the above described routine constantly judge whether or not an operating state in which the NO 2 -based regeneration can be executed sufficiently during operation of the internal combustion engine 10 is established.
  • the transition to the NO 2 -based regeneration mode is permitted, and thereby, the engine control parameters are changed so as to facilitate the NO 2 -based regeneration as much as possible.
  • the NO 2 -based regeneration mode is executed only in a sufficient operating state concerning the NO 2 -based regeneration that is detected during operation of the internal combustion engine 10 (an operating state in which the NO 2 -based regeneration can be executed in a short time)
  • the execution period of the NO 2 -based regeneration mode can be prevented from becoming too long. This can ensure the opportunity in which the NO 2 -based regeneration is efficiently performed during operation while suppressing an increase in the amount of NOx emission and the deterioration of fuel efficiency as much as possible.
  • FIG. 4 is a chart for explaining the effect of control of the NO 2 -based regeneration according to the first embodiment of the present invention. It is noted that the waveform represented “Conventional control” by the broken line in FIG. 4 shows one to which the control according to the present embodiment is not applied.
  • the present embodiment changes the engine control parameters within a range in which the deterioration of NOx emission and fuel efficiency is prevented as much as possible, on the condition that an operation condition that requires the trade-off is not met.
  • transitioning to the NO 2 -based regeneration mode is prohibited when any of the aforementioned predetermined engine operation conditions subject to prohibition of NO 2 -based regeneration is met.
  • Such control that prohibits the transitioning to the NO 2 -based regeneration mode at the time of low-temperature produces the following advantageous effects. More specifically, if the amount of EGR gas is decreased or the introduction of EGR is ceased as a result of the transitioning to the NO 2 -based regeneration mode at the time of low-temperature, heat becomes hard to be obtained when the engine cooling water flows through the EGR cooler 40 .
  • the transitioning to the NO 2 -based regeneration mode is prohibited at the time of execution of the torque control that maintains engine torque at a constant value, such as the time of idling operation and the time of cruise control, and thereby a torque shock can be prevented from occurring due to a change in the engine control parameters for facilitating the NO 2 -based regeneration.
  • the transitioning to the NO 2 -based regeneration mode is prohibited at the time of traveling in an urban area, and thereby the amount of NOx emission can be prevented from increasing due to facilitation of the NO 2 -based regeneration when the traveling in an urban area is done.
  • the implementation of the prohibition condition has priority over ensuring the opportunity of the NO 2 -based regeneration. That is to say, ensuring the opportunity of the NO 2 -based regeneration by the control of the present embodiment can be permitted consistently under a situation in which there is no concern about any adverse effects.
  • the execution of the NO 2 -based regeneration mode is not maintained until the amount of soot accumulation decreases to a target value, but the execution is immediately suspended.
  • Such control more definitely ensures the execution of the NO 2 -based regeneration that is limited at efficient operating states and the execution of the NO 2 -based regeneration that is limited under engine operation conditions in which there is no concern about any adverse effects.
  • the DPF 28 corresponds to the “particulate filter” according to the present invention
  • the DOC 26 corresponds to the “NO 2 production means” according to the present invention.
  • the ECU 50 calculates the NO 2 -based regeneration speed using the NO 2 -based regeneration speed model shown in FIG. 3 , whereby the “NO 2 -based regeneration speed estimation means” according to the present invention is realized; the ECU 50 executes the aforementioned determination of step 100 , whereby the “operating state determination means” according to the present invention is realized; and the ECU 50 executes the aforementioned processing of step 104 , whereby the “control parameter change means” according to the present invention is realized.
  • the ECU 50 executes the aforementioned processing of step 106 when the aforementioned determination of step 102 is not established, whereby the “first control parameter change prohibition means” according to the present invention is realized.
  • the ECU 50 executes the aforementioned processing of step 106 when the aforementioned determination of step 102 is not established, whereby the “second control parameter change prohibition means” according to the present invention is realized.
  • the ECU 50 executes the aforementioned processing of step 106 when the aforementioned determination of step 102 is not established, whereby the “third control parameter change prohibition means” according to the present invention is realized.
  • the ECU 50 executes the aforementioned processing of step 106 when the aforementioned determination of step 100 or 102 is negative, whereby the “parameter change suspend means” according to the present invention is realized.

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US14/347,497 2011-11-25 2011-11-25 Control apparatus for internal combustion engine Abandoned US20140216017A1 (en)

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US20150089941A1 (en) * 2013-09-30 2015-04-02 Mazda Motor Corporation Exhaust gas recirculation control device of engine
US20150267589A1 (en) * 2012-10-16 2015-09-24 Doosan Corporation Multi-step regeneration device of dpf and regeneration method therefor
CN105298602A (zh) * 2015-11-05 2016-02-03 武汉华威专用汽车检测有限责任公司 一种微粒捕集器实时在线更新再生控制方法
US20160069300A1 (en) * 2014-09-10 2016-03-10 Mazda Motor Corporation Exhaust gas recirculation control device for engine
US10920701B2 (en) 2016-06-03 2021-02-16 Isuzu Motors Limited Filter regeneration system for internal combustion engine and filter regeneration method for internal combustion engine
US20230135221A1 (en) * 2020-02-28 2023-05-04 Vitesco Technologies GmbH Method and Device for Diagnosing a Coated Particulate Filter Arranged in an Exhaust-Gas Duct of a Motor Vehicle

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US20150135679A1 (en) * 2013-11-21 2015-05-21 General Electric Company Emissions control in diesel engines

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US20150267589A1 (en) * 2012-10-16 2015-09-24 Doosan Corporation Multi-step regeneration device of dpf and regeneration method therefor
US10508581B2 (en) * 2012-10-16 2019-12-17 Doosan Corporation Multi-step regeneration device of DPF and regeneration method therefor
US9464586B2 (en) * 2013-09-20 2016-10-11 Mazda Motor Corporation Exhaust gas recirculation system of engine
US20150089941A1 (en) * 2013-09-30 2015-04-02 Mazda Motor Corporation Exhaust gas recirculation control device of engine
US20160069300A1 (en) * 2014-09-10 2016-03-10 Mazda Motor Corporation Exhaust gas recirculation control device for engine
US10323592B2 (en) * 2014-09-10 2019-06-18 Mazda Motor Corporation Exhaust gas recirculation (EGR) control device for engine including an EGR amount increase control
CN105298602A (zh) * 2015-11-05 2016-02-03 武汉华威专用汽车检测有限责任公司 一种微粒捕集器实时在线更新再生控制方法
US10920701B2 (en) 2016-06-03 2021-02-16 Isuzu Motors Limited Filter regeneration system for internal combustion engine and filter regeneration method for internal combustion engine
US20230135221A1 (en) * 2020-02-28 2023-05-04 Vitesco Technologies GmbH Method and Device for Diagnosing a Coated Particulate Filter Arranged in an Exhaust-Gas Duct of a Motor Vehicle
US12044157B2 (en) * 2020-02-28 2024-07-23 Vitesco Technologies GmbH Method and device for diagnosing a coated particulate filter arranged in an exhaust-gas duct of a motor vehicle

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EP2784276A4 (fr) 2014-11-05

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