US20120144802A1 - Exhaust system having doc regeneration strategy - Google Patents

Exhaust system having doc regeneration strategy Download PDF

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Publication number
US20120144802A1
US20120144802A1 US12/965,525 US96552510A US2012144802A1 US 20120144802 A1 US20120144802 A1 US 20120144802A1 US 96552510 A US96552510 A US 96552510A US 2012144802 A1 US2012144802 A1 US 2012144802A1
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Prior art keywords
exhaust
fuel
temperature
oxidation catalyst
oxide layer
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Abandoned
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US12/965,525
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English (en)
Inventor
James J. Driscoll
Duncan J. Arrowsmith
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Caterpillar Inc
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Caterpillar Inc
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Publication date
Application filed by Caterpillar Inc filed Critical Caterpillar Inc
Priority to US12/965,525 priority Critical patent/US20120144802A1/en
Assigned to CATERPILLAR INC. reassignment CATERPILLAR INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ARROWSMITH, DUNCAN J., DRISCOLL, JAMES J.
Priority to CN2011800595543A priority patent/CN103261603A/zh
Priority to DE112011104327T priority patent/DE112011104327T5/de
Priority to PCT/US2011/062355 priority patent/WO2012078402A2/en
Publication of US20120144802A1 publication Critical patent/US20120144802A1/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
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • 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
    • F01N3/025—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 fuel burner or by adding fuel to exhaust
    • F01N3/0253—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 fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
    • 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
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust 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
    • F01N3/103—Oxidation catalysts for HC and CO only
    • 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
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust 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
    • F01N3/18—Exhaust 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 characterised by methods of operation; Control
    • F01N3/20—Exhaust 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 characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • F01N3/2033—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using a fuel burner or introducing fuel into exhaust duct
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present disclosure is directed to an exhaust system and, more particularly, to an exhaust system having a strategy for regenerating a diesel oxidation catalyst (DOC).
  • DOC diesel oxidation catalyst
  • Diesel oxidation catalysts are commonly used in the exhaust systems of internal combustion engines to facilitate different emission reduction processes.
  • DOCs can be used to create a desired ratio of NO to NO 2 in an engine's exhaust stream that enhances NO X reduction within a downstream selective catalytic reduction (SCR) device.
  • SCR selective catalytic reduction
  • DOCs can be used to increase an overall amount of NO 2 in the exhaust stream passing through a diesel particulate filter (DPF) to lower a combustion temperature of particulate matter trapped in the DPF and thereby enhance passive regeneration of the DPF.
  • DPF diesel particulate filter
  • DOCs can also be problematic under some conditions. That is, it has been found that the active catalytic materials of a DOC, which commonly include precious materials such as Platinum, can become less active when exposed to high temperatures. Consequently, as the DOC cools after reaching high temperatures or operates for an extended period of time at the high temperatures, the DOC is less capable of generating NO 2 .
  • the exhaust system may include an exhaust passage configured to receive a flow of exhaust from the combustion engine, and an oxidation catalyst disposed within the exhaust passage.
  • the exhaust system may also include a fuel injector configured to selectively inject fuel into the exhaust at a location upstream of the oxidation catalyst, a temperature sensor configured to generate a signal indicative of a temperature of exhaust flowing through the exhaust passage, and a controller in communication with the fuel injector and the temperature sensor.
  • the controller may be configured to make a determination based on the signal that an oxide layer has formed on the oxidation catalyst, and to regulate operation of the fuel injector to inject fuel and reduce the oxide layer based on the determination.
  • the method may include directing exhaust through an oxidation catalyst, and making a determination that an oxide layer has formed on the oxidation catalyst.
  • the method may further include selectively introducing a burst of fuel into exhaust directed through the oxidation catalyst to reduce the oxide layer based on the determination.
  • FIG. 1 is a schematic and diagrammatic illustration of an exemplary disclosed power system
  • FIG. 2 is a graph illustrating an operation of the power system of FIG. 1 .
  • FIG. 1 illustrates an exemplary power system 10 .
  • power system 10 is depicted and described as a diesel-fueled internal combustion engine.
  • power system 10 may embody any other type of combustion engine such as, for example, a gasoline engine or a gaseous fuel-powered engine burning compressed or liquefied natural gas, propane, or methane.
  • Power system 10 may include an engine block 12 that at least partially defines a plurality of combustion chambers 14 provided with fuel via a plurality of fuel injectors 15 . It is contemplated that power system 10 may include any number of combustion chambers 14 and that combustion chambers 14 may be disposed in an “in-line” configuration, a “V” configuration, or in any other conventional configuration.
  • power system 10 may include an air induction system 16 , an exhaust system 18 , and a control system 20 .
  • Air induction system 16 may be configured to direct air into combustion chambers 14 of power system 10 to mix with fuel from injectors 15 for subsequent combustion.
  • Exhaust system 18 may exhaust byproducts of the combustion to the atmosphere.
  • Control system 20 may regulate operations of air induction and exhaust systems 16 , 18 to reduce the production of regulated constituents and/or their discharge to the atmosphere.
  • Air induction system 16 may include multiple components that cooperate to condition and introduce compressed air into combustion chambers 14 .
  • air induction system 16 may include an air cooler 22 located downstream of one or more compressors 24 .
  • Compressors 24 may be connected to pressurize inlet air directed through cooler 22 .
  • a throttle valve (not shown) may be located upstream and/or downstream of compressors 24 to selectively regulate (i.e., restrict) the flow of inlet air into power system 10 .
  • a restriction on the flow of inlet air may result in less air entering power system 10 and, thus, affect an air-to-fuel ratio of power system 10 .
  • air induction system 16 may include different or additional components than described above such as, for example, variable valve actuators associated with each combustion chamber 14 , filtering components, compressor bypass components, and other known components that may be selectively controlled to affect the air-to-fuel ratio of power system 10 , if desired. It is further contemplated that compressors 24 and/or cooler 22 may be omitted, if a naturally aspirated power system 10 is desired.
  • Exhaust system 18 may include multiple components that condition and direct exhaust from combustion chambers 14 to the atmosphere.
  • exhaust system 18 may include an exhaust passage 26 , one or more turbines 28 driven by exhaust flowing through passage 26 , and a plurality of exhaust treatment devices fluidly connected within passage 26 at a location downstream of turbines 28 .
  • exhaust system 18 may include different or additional components than described above such as, for example, exhaust gas recirculation (EGR) components, bypass components, an exhaust compression or restriction brake, an attenuation device, and other known components, if desired.
  • EGR exhaust gas recirculation
  • Each turbine 28 may be located to receive exhaust discharged from combustion chambers 14 , and may be connected to one or more compressors 24 of air induction system 16 by way of a common shaft 30 to form a turbocharger. As the hot exhaust gases exiting power system 10 move through turbine 28 and expand against vanes (not shown) thereof, turbine 28 may rotate and drive the connected compressor 24 to pressurize inlet air.
  • turbine 28 may be a variable geometry turbine (VGT) or include a combination of variable and fixed geometry turbines.
  • VGTs are a type of turbocharger having geometry adjustable to attain different aspect ratios, such that adequate boost pressure may be supplied to combustion chambers 14 under a range of operational conditions. As a flow area of turbine 28 changes, the air-to-fuel ratio and thus the performance of power system 10 may also change.
  • a fixed geometry turbocharger with or without an electronically controlled wastegate may be included, if desired.
  • the treatment devices of exhaust system 18 may receive exhaust from turbine 28 and reduce or remove constituents of the exhaust.
  • the exhaust treatment devices may include one or more of a diesel particulate filter (DPF) 32 and a selective catalytic reduction (SCR) device 34 .
  • a particulate filter is a device designed to trap particulate matter and typically consists of a wire mesh or ceramic honeycomb medium. As exhaust laden with particulate matter passes through the filter, the particulate matter is blocked by the filter and suspended from the exhaust flow.
  • SCR device 34 may include a catalyst substrate 36 located downstream from an injector 38 .
  • a pressurized gaseous or liquid reductant most commonly urea (NH 2 ) 2 CO or a water/urea mixture may be selectively advanced into the exhaust upstream of catalyst substrate 36 by injector 38 .
  • An onboard reductant supply 40 and a pressurizing device 42 may be associated with injector 38 to provide the pressurized reductant.
  • the reductant may react with NOx (NO and NO 2 ) in the exhaust gas to form water (H 2 O) and diatomic nitrogen (N 2 ).
  • particulate trap 32 and/or SCR device 34 may be enhanced by an upstream-located diesel oxidation catalyst (DOC) 44 .
  • DOC diesel oxidation catalyst
  • particulate matter may build up therein and, if unaccounted for, eventually restrict the exhaust flow through DPF 32 by an undesired amount. Accordingly, DPF 32 may be selectively regenerated to reduce the amount of particulate matter buildup.
  • the temperature of the particulate matter entrained within DPF 32 must be elevated above a combustion threshold temperature at which the trapped particulate matter is burned away, for example above about 600° C. Under most conditions, however, this threshold temperature is not achieved naturally.
  • DOC 44 may generate an amount of NO 2 in the exhaust flow passing through DPF 32 that helps to lower the combustion threshold temperature to a level that allows combustion of trapped particulate matter under normal operating conditions. This type of regeneration may be known as passive regeneration. Similarly, the reduction process performed by SCR device 34 may be most effective when a concentration of NO to NO 2 supplied to SCR device is about 1:1, and DOC 44 may help provide this concentration.
  • DOC 44 may include a porous ceramic honeycomb structure or a metal mesh substrate coated with a material, for example a washcoat containing precious metals, that catalyzes a chemical reaction to alter the composition of the exhaust.
  • DOC 44 may include a washcoat of palladium, platinum, vanadium, or a mixture thereof that facilitates the conversion of a portion of the NO already existing in the exhaust flow of power system 10 to NO 2 .
  • the exhaust flow having an increased amount of NO 2 may then be directed into DPF 32 to facilitate passive regeneration therein and/or into SCR device 34 to facilitate the reduction of NO X .
  • FIG. 2 illustrates a first curve 200 representing operation of a typical DOC during an initial operation of a corresponding power source as the power source heats up, and a second curve 210 representing operation of the same DOC after an extended period of time at elevated temperatures and during cooling of the power source.
  • the typical DOC will initially perform well and convert an increasing amount of NO to NO 2 until exhaust temperatures reach about 180° C. Once exhaust temperatures reach about 180° C. and continue to increase, however, the conversion efficiency of the typical DOC may reduce. And, the conversion efficiency drops dramatically as the DOC cools after extended operation at elevated temperatures. For example, when cooling from about 250° C. to about 200° C., the efficiency shown in curve 210 may be about half of the initial efficiency shown in curve 200 . Further, if reheated before sufficient cooling has occurred, the efficiency of the typical DOC will follow the reduced efficiency curve 210 rather than curve 200 .
  • an injector 46 may be disposed at a location upstream of DOC 44 and configured to selectively inject bursts of a hydrocarbon, for example diesel fuel, into exhaust passage 26 .
  • a hydrocarbon for example diesel fuel
  • An onboard hydrocarbon supply 48 and a pressurizing device 50 may be associated with injector 46 to provide the pressurized hydrocarbon.
  • Control system 20 may include components configured to regulate the treatment of exhaust from power system 10 prior to discharge to the atmosphere.
  • control system 20 may include a controller 52 in communication with one or more exhaust sensors 54 , injector 38 , and injector 46 . Based on input from exhaust sensor 54 and/or other input, controller 52 may determine an amount of NO X being produced by power system 10 , a performance of SCR device 34 , the formation of the oxide layer on DOC 44 , a desired amount of urea that should be sprayed by injector 38 into the exhaust flow, a desired amount of hydrocarbon that should be sprayed by injector 46 into the exhaust flow, and/or other similar control parameters. Controller 52 may then regulate operation of injectors 38 and 46 such that the desired amounts of urea and hydrocarbon are sprayed into the exhaust flow upstream of catalyst substrate 36 and DOC 44 , respectively.
  • Controller 52 may embody a single or multiple microprocessors, field programmable gate arrays (FPGAs), digital signal processors (DSPs), etc. that include a means for controlling an operation of power system 10 in response to signals received from the various sensors. Numerous commercially available microprocessors can be configured to perform the functions of controller 52 . It should be appreciated that controller 52 could readily embody a microprocessor separate from that controlling other non-exhaust related power system functions, or that controller 52 could be integral with a general power system microprocessor and be capable of controlling numerous power system functions and modes of operation. If separate from the general power system microprocessor, controller 52 may communicate with the general power system microprocessor via datalinks or other methods.
  • FPGAs field programmable gate arrays
  • DSPs digital signal processors
  • controller 52 Various other known circuits may be associated with controller 52 , including power supply circuitry, signal-conditioning circuitry, actuator driver circuitry (i.e., circuitry powering solenoids, motors, or piezo actuators), communication circuitry, and other appropriate circuitry.
  • actuator driver circuitry i.e., circuitry powering solenoids, motors, or piezo actuators
  • Exhaust sensor 54 of control system 20 may be configured to generate a signal indicative of formation of the oxide layer on the metallic substrate of DOC 44 .
  • exhaust sensor 54 may be a temperature sensor configured to generate a signal corresponding to a temperature of the exhaust passing through DOC 44 , and send this signal to controller 52 .
  • controller 52 may make a determination that it is likely that the oxide layer has formed.
  • the threshold temperature may be about 180-250° C. and correspond with about 60-100% of the substrate of DOC 44 being covered by the oxide layer.
  • controller 52 may make the determination that the oxide layer has formed.
  • exhaust sensor 54 may be a type of sensor other than a temperature sensor, if desired, and that controller 52 may be configured to similarly make the determination regarding formation of the oxide layer based on the corresponding signal(s) from that sensor.
  • exhaust sensor 54 could alternatively embody a NO X sensor configured to detect an amount of NO and/or NO 2 in the exhaust exiting DOC 44 , with controller 52 then being configured to determine formation of the oxide layer based on the sensed conversion performance of DOC 44 .
  • exhaust sensor 54 could alternatively embody a particulate filter sensor configured to generate signals indicative of lower than expected regeneration rates of DPF 32 as determined by an amount of soot detected within or downstream of DPF 32 , and/or a pressure differential across DPF 32 .
  • sensor 54 may alternatively embody a virtual sensor.
  • a virtual sensor may produce a model-driven estimate based on one or more known or sensed operational parameters of power system 10 and/or DOC 44 . For example, based on a known operating speed, load, temperature, boost pressure, ambient conditions (humidity, pressure, temperature), and/or other parameter of power system 10 , a model may be referenced to determine formation of the oxide layer on DOC 44 . Similarly, based on a known or estimated NOx production of power system 10 , a flow rate of exhaust exiting power system 10 , and/or a temperature of the exhaust, the model may be referenced to determine the formation of the oxide layer.
  • the signal directed from sensor 54 to controller 52 may be based on calculated and/or estimated values rather than direct measurements, if desired. It is contemplated that rather than a separate element, these virtual sensing functions may be accomplished by controller 52 , if desired.
  • controller 52 may selectively cause injector 46 to inject one or more bursts of hydrocarbon into the exhaust at a location upstream of DOC 44 . For example, after the temperature of the exhaust at DOC 44 exceeds 180° C. and/or remains above 180° C. for at least 2 seconds, controller 52 may energize injector 46 to inject an amount of hydrocarbon necessary to remove or otherwise reduce the corresponding oxide layer.
  • the amount of hydrocarbon injected during a single oxide-dissolving event may be about 100-1000 ppm or about 1/100-1/1000 of a total amount of fuel consumed (i.e., including fuel used for normal combustion purposes) by power system 10 during the event, and have an injection duration of about 5-300 seconds.
  • This amount of hydrocarbon may serve primarily to remove some or all of the oxide layer and have little affect on the air-to-fuel ratio or the temperature of exhaust within passage 26 .
  • the injected hydrocarbon may raise the air-to-fuel ratio of the exhaust within passage 26 by less than about 5% and increase a temperature of the exhaust by less than about 30° C.
  • the injection of hydrocarbon has been shown to remove the oxide layer to less than about 20% of the substrate surface of DOC 44 in as little as about 5-300 seconds, depending on the application.
  • controller 52 may delay the injections of hydrocarbon until the exhaust temperatures have peaked and cooling of the exhaust is observed. This cooling may correspond, for example, with idling of power system 10 or a particular segment of an excavation cycle such as a dump or return segment that requires less output from power system 10 . Controller 52 may determine that temperatures have peaked and the exhaust is cooling when controller 52 detects a temperature drop of about 5-20° C. over a one minute time period.
  • controller 52 after triggering the initial hydrocarbon injections according to the strategy outlined above, may continue to inject bursts of hydrocarbon as long as exhaust temperatures remain elevated. For example, after the initial burst of hydrocarbon, injector 46 may be controlled to inject subsequent bursts of hydrocarbon about every five minutes.
  • the exhaust system of the present disclosure may be applicable to any power system having an oxidation catalyst, where continued performance at a desired level is important.
  • the performance of DOC 44 may be extended through selective injections of hydrocarbon into the exhaust flow of power system 10 at a location upstream of DOC 44 when it is determined to be likely that an oxide layer has formed on DOC 44 . Operation of power system 10 will now be described.
  • air induction system 16 may pressurize and force air or a mixture of air and fuel into combustion chambers 14 of power system 10 for subsequent combustion.
  • the fuel and air mixture may be combusted by power system 10 to produce a mechanical work output and an exhaust flow of hot gases.
  • the exhaust flow may contain a complex mixture of air pollutants composed of gaseous material, which can include oxides of nitrogen (NO X ). As this NO X -laden exhaust flow is directed from combustion chambers 14 through oxidation catalyst 44 , some NO in the flow may be converted to NO 2 .
  • NO X oxides of nitrogen
  • the exhaust flow containing an increased amount of NO 2 may be directed through DPF 32 and SCR 34 .
  • particulate matter in the exhaust may be removed by DPF 32 and NO X in the exhaust may be reduced to innocuous substances.
  • the increased amount of NO 2 generated by DOC 44 may facilitate passive regeneration of DPF 32 and enhance the reduction of NO X within SCR 34 .
  • controller 52 may monitor the signals from exhaust sensor 54 (Step 300 ) and determine if exhaust temperatures have remained above 180° C. for at least 2 seconds (Step 310 ).
  • controller 52 may await the next exhaust cooling event (e.g., an event where exhaust temperatures cool by about 5-20° C. within a one minute time period) (Step 310 ), and then initiate regeneration of DOC 44 by causing injector 46 to selectively inject bursts of hydrocarbon (i.e., diesel fuel) into the exhaust of passage 26 at a location upstream of DOC 44 (Step 330 ).
  • This injected hydrocarbon when it comes into contact with the oxide layer, may facilitate a chemical reaction that removes the oxide layer and restores functionality to DOC 44 .
  • controller 52 may cause injector 46 to inject additional bursts of hydrocarbon on a regular basis, for example every five minutes (Step 340 ), without waiting for a cooling event to occur.
  • the disclosed injections of hydrocarbon may be capable of dissolving the oxide layer of a DOC in a very short amount of time with very little hydrocarbon.
  • a relatively small injection of hydrocarbon i.e., about 1/100-1/1000 of a total amount of fuel consumed
  • the disclosed system may be very responsive and efficient.
  • many power systems may already be equipped with an exhaust-located fuel injector used to actively regenerate a DPF and/or heat an SCR device. Accordingly, selective use of this same fuel injector to regenerate a DOC may require little or no new hardware.
  • fuel injectors 15 may additionally be utilized to inject the small quantities of fuel required for the removal at a timing when the injected fuel will not fully combust within cylinders 14 (e.g., in a late post injection or during an injection when corresponding cylinders 14 are disabled).
  • injectors 15 are utilized to regenerate DOC 44 , injector 46 , supply 48 , and device 50 may be omitted. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Materials Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Processes For Solid Components From Exhaust (AREA)
US12/965,525 2010-12-10 2010-12-10 Exhaust system having doc regeneration strategy Abandoned US20120144802A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US12/965,525 US20120144802A1 (en) 2010-12-10 2010-12-10 Exhaust system having doc regeneration strategy
CN2011800595543A CN103261603A (zh) 2010-12-10 2011-11-29 具有dco再生策略的排气系统
DE112011104327T DE112011104327T5 (de) 2010-12-10 2011-11-29 Abgassystem mit einer DOC-Regenerationsstrategie
PCT/US2011/062355 WO2012078402A2 (en) 2010-12-10 2011-11-29 Exhaust system having doc regeneration strategy

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CN (1) CN103261603A (de)
DE (1) DE112011104327T5 (de)
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US20110041815A1 (en) * 2007-02-05 2011-02-24 Volvo Lastvagnar Ab Exhaust purification system with a diesel particulate filter and a method of cleaning said filter
US20110283680A1 (en) * 2009-02-20 2011-11-24 Ioannis Gekas Method for purification of exhaust gas from a diesel engine
US20130111877A1 (en) * 2011-11-04 2013-05-09 GM Global Technology Operations LLC System and method for particulate filter regeneration
US20140019028A1 (en) * 2012-07-16 2014-01-16 Ford Global Technologies, Llc Differential fuel injection
US20140112851A1 (en) * 2011-06-10 2014-04-24 Edward M. Derybowski Supplemental ammonia storage and delivery system
WO2015057308A1 (en) * 2013-10-18 2015-04-23 Cummins Ip, Inc. Gasoline dithering for spark-ignited gaseous fuel internal combustion engine
US20170184003A1 (en) * 2014-07-08 2017-06-29 Toyota Jidosha Kabushiki Kaisha Filter failure diagnostic device for an internal combustion engine
US20170292423A1 (en) * 2016-04-12 2017-10-12 Toyota Jidosha Kabushiki Kaisha Exhaust Purification Control Device for Internal Combustion Engine
CN109578117A (zh) * 2018-12-03 2019-04-05 潍柴动力股份有限公司 一种柴油氧化催化器的恢复方法及装置

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