US20160273433A1 - Exhaust gas treatment apparatus and exhaust gas treatment method for internal combustion engine - Google Patents
Exhaust gas treatment apparatus and exhaust gas treatment method for internal combustion engine Download PDFInfo
- Publication number
- US20160273433A1 US20160273433A1 US15/072,573 US201615072573A US2016273433A1 US 20160273433 A1 US20160273433 A1 US 20160273433A1 US 201615072573 A US201615072573 A US 201615072573A US 2016273433 A1 US2016273433 A1 US 2016273433A1
- Authority
- US
- United States
- Prior art keywords
- exhaust gas
- catalytic converter
- exhaust
- zone
- gas treatment
- 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.)
- Abandoned
Links
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Images
Classifications
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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
- F01N3/08—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
- F01N3/24—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 constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2892—Exhaust flow directors or the like, e.g. upstream of catalytic device
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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
- F01N13/00—Exhaust 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
- F01N13/08—Other arrangements or adaptations of exhaust conduits
- F01N13/082—Other arrangements or adaptations of exhaust conduits of tailpipe, e.g. with means for mixing air with exhaust for exhaust cooling, dilution or evacuation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- 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
- F01N3/0892—Electric or magnetic treatment, e.g. dissociation of noxious components
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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
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
- F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
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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
- F01N13/00—Exhaust 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
- F01N13/08—Other arrangements or adaptations of exhaust conduits
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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
- F01N13/00—Exhaust 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
- F01N13/14—Exhaust 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 thermal insulation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- F01N13/00—Exhaust 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
- F01N13/14—Exhaust 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 thermal insulation
- F01N13/141—Double-walled exhaust pipes or housings
- F01N13/143—Double-walled exhaust pipes or housings with air filling the space between both walls
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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
- F01N13/00—Exhaust 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
- F01N13/18—Construction facilitating manufacture, assembly, or disassembly
- F01N13/1833—Construction facilitating manufacture, assembly, or disassembly specially adapted for small internal combustion engines, e.g. used in model applications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- 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
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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
- F01N3/033—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 in combination with other devices
- F01N3/035—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 in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
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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
- F01N3/08—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
- F01N3/24—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 constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2882—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices
- F01N3/2889—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices with heat exchangers in a single housing
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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
- F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
- F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- F01N9/00—Electrical control of exhaust gas treating apparatus
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
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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
- F01N13/00—Exhaust 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
- F01N13/009—Exhaust 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
- F01N13/0097—Exhaust 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 the purifying devices are arranged in a single housing
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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
- F01N2240/00—Combination 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
- F01N2240/02—Combination 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 a heat exchanger
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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
- F01N2240/00—Combination 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
- F01N2240/20—Combination 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 a flow director or deflector
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- F01N2240/00—Combination 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
- F01N2240/28—Combination 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 a plasma reactor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F01N2250/00—Combinations of different methods of purification
- F01N2250/02—Combinations of different methods of purification filtering and catalytic conversion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- F01N2330/00—Structure of catalyst support or particle filter
- F01N2330/60—Discontinuous, uneven properties of filter material, e.g. different material thickness along the longitudinal direction; Higher filter capacity upstream than downstream in same housing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
- F01N2550/02—Catalytic activity of catalytic converters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/07—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas flow rate or velocity meter or sensor, intake flow meters only when exclusively used to determine exhaust gas parameters
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- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
- F01N2900/1411—Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
- F01N2900/1602—Temperature of exhaust gas apparatus
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- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
- F01P2025/00—Measuring
- F01P2025/08—Temperature
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- 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
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- 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
- Embodiments of the present invention relate to an apparatus and method for treating exhaust gas that is emitted from an internal combustion engine.
- an exhaust gas turbine of a supercharger, a catalytic converter of an exhaust gas control apparatus, a muffler, and the like are closely arranged in an exhaust passage that guides exhaust gas that is emitted from an internal combustion engine mounted on a vehicle, so an exhaust pipe that connects these devices needs to be significantly bent.
- the passage sectional area of the catalytic converter of the exhaust gas control apparatus may be about several times as large as the passage sectional area of the exhaust pipe for the purpose of increasing exhaust gas purification efficiency.
- it is required to decrease the space velocity of exhaust gas by diffusing exhaust gas, which flows into the catalytic converter, over the entire area of an end face of the catalytic converter. Therefore, a large-diameter casing that accommodates the catalytic converter and a small-diameter exhaust pipe that is connected to the casing are coupled to each other via a tapered member called a cone for diffusing exhaust gas.
- the length of the tapered member tends to be extremely short.
- the flow direction of exhaust gas that passes through the catalytic converter often significantly differs from the flow direction of exhaust gas that flows from the exhaust pipe into the tapered member.
- exhaust gas that flows along a wall face of the exhaust passage from the small-diameter exhaust pipe to the catalytic converter via the tapered member burbles away from the wall face of the exhaust passage at the connection point at which the exhaust pipe is connected to the tapered member.
- exhaust gas that passes through the tapered member flows into only the zone of part of the catalytic converter without diffusing so much, with the result that it is not possible to maximally utilize the purification performance of the catalytic converter.
- JP 2012-193719 A a technique for forcibly distributing the flow direction of exhaust gas by incorporating a louver in an exhaust pipe on the inlet side of the catalytic converter has been suggested in Japanese Patent Application Publication No. 2012-193719 (JP 2012-193719 A).
- louver member as described in JP 2012-193719 A is incorporated in the exhaust passage, passage resistance increases and, in addition, the louver member absorbs heat of exhaust gas at the time of a warm-up of the internal combustion engine, with the result that the time to complete a warm-up is extended. This leads to deterioration of fuel economy.
- Embodiments of the present invention provide an exhaust gas treatment apparatus and exhaust gas treatment method that are able to diffuse exhaust gas over the entire area of a catalytic converter without increasing passage resistance as described in JP 2012-193719 A even with a configuration where the flow direction of exhaust gas from an exhaust pipe to the catalytic converter steeply bends.
- An embodiment of the present invention also provides an exhaust gas treatment apparatus and exhaust gas treatment method that, even when the amount of exhaust gas flowing into an exhaust gas treatment unit tends to reduce because of steep bending of an exhaust pipe, is able to prevent at least a reduction in the amount of exhaust gas flowing into the exhaust gas treatment unit without increasing passage resistance.
- a first embodiment of the invention provides an exhaust gas treatment apparatus for an internal combustion engine.
- the exhaust gas treatment apparatus includes: an exhaust gas treatment unit arranged in an exhaust passage of the internal combustion engine, the exhaust passage being configured such that i) exhaust gas flowing along a part of a wall face, which defines the exhaust passage, burbles away from the part of the wall face in an exhaust gas burble zone and ii) as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone, exhaust gas disproportionately flows into the exhaust gas treatment unit or the amount of exhaust gas flowing into the exhaust gas treatment unit reduces.
- a plasma actuator is provided arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, the plasma actuator being configured to generate air current toward the exhaust gas treatment unit along the part of the wall face in exhaust gas inside the exhaust passage.
- air current is generated toward the exhaust gas treatment unit along the part of the wall face of the exhaust passage in the exhaust gas burble zone.
- exhaust gas flowing along the part of the wall face of the exhaust passage in the exhaust gas burble zone is dragged by the air current, flows without burbling away from the part of the wall face of the exhaust passage, and then flows into the exhaust gas treatment unit in a diffused state or a reduction in the amount of exhaust gas flowing into the exhaust gas treatment unit is suppressed.
- a sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone, taken along a flow direction of exhaust gas may include a convex curved line.
- the exhaust gas treatment apparatus may further include a flow rate acquisition device configured to acquire a flow rate of exhaust gas flowing through the exhaust passage; and a controller configured to control the amount of energy that is input to the plasma actuator.
- the exhaust gas treatment unit may include a catalytic converter configured to purify exhaust gas, and the controller may be configured to control the plasma actuator such that the amount of energy that is input to the plasma actuator increases as the acquired flow rate of exhaust gas increases.
- the exhaust gas treatment apparatus may further include a temperature acquisition device configured to acquire a temperature of the catalytic converter, and the controller may be configured to, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, input energy to the plasma actuator.
- a mode of controlling the amount of energy that is input to the plasma actuator may include changing an applied voltage or a driving frequency.
- the exhaust gas treatment unit may include a catalytic converter configured to purify exhaust gas, the exhaust gas treatment apparatus may further include a temperature acquisition device configured to acquire a temperature of the catalytic converter; and a controller configured to control the amount of energy that is input to the plasma actuator, and the controller may be configured to, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, input energy to the plasma actuator.
- the controller may be configured to, when the acquired temperature of the catalytic converter is lower than or equal to an upper limit temperature of the catalytic converter, input energy to the plasma actuator.
- the upper limit temperature of the catalytic converter means a maximum temperature at or below which degradation, dissolution loss, or the like, of the catalytic converter due to heat does not occur. Therefore, it may be understood that degradation, dissolution loss, or the like, of the catalytic converter begins when the temperature exceeds the upper limit temperature.
- a cylindrical heat insulation partition surrounding a zone of part of the catalytic converter along a flow direction of exhaust gas may be provided in the catalytic converter.
- the zone surrounded by the heat insulation partition may include a zone into which exhaust gas disproportionately flows as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone.
- the length of the heat insulation partition along the flow direction of exhaust gas may be shorter than the length of the catalytic converter along the flow direction of exhaust gas, and an upstream end of the heat insulation partition along the flow direction of exhaust gas may be located at an upstream end of the catalytic converter along the flow direction of exhaust gas.
- upstream or upstream side means a side closer to a combustion chamber of the internal combustion engine; whereas, the word “downstream” or “downstream side” means a side away from the combustion chamber of the internal combustion engine.
- the heat insulation partition may be an air layer.
- the acquired temperature of the catalytic converter may be a temperature of a zone different from a zone into which exhaust gas from a small-diameter portion flows because of the exhaust gas burble zone.
- the exhaust gas treatment apparatus may further include a particulate filter configured to trap particulate matter contained in exhaust gas, and the particulate filter may be arranged downstream of the catalytic converter.
- the exhaust passage may be branched into two by a partition wall extending along a flow direction of exhaust gas
- the exhaust gas treatment unit may include an exhaust heat recovery device arranged in one of the branched exhaust passages and configured to exchange heat between exhaust gas flowing through this branched exhaust passages and coolant of the internal combustion engine.
- the exhaust gas burble zone may be located at a portion at which the exhaust passage is branched, and the exhaust passage may be configured such that the amount of exhaust gas flowing into the branched exhaust passage mentioned above reduces as a result of burble of exhaust gas away from a part of a wall face of the exhaust passage in the exhaust gas burble zone.
- the exhaust gas treatment apparatus may further include a coolant temperature sensor configured to acquire a temperature of coolant of the internal combustion engine, and the controller may be configured to, when the acquired temperature of coolant is lower than a temperature set in advance, input energy to the plasma actuator.
- a clearance from a part of the wall face, which defines the aforementioned branched exhaust passage, to the partition wall along a direction perpendicular to the partition wall may be set so as to be shorter than a clearance from the part of the wall face, which defines this branched exhaust passage, to the wall face that defines the exhaust passage just before branching along the direction perpendicular to the partition wall.
- a plurality of the exhaust gas treatment units may be arranged in series along the exhaust passage, the upstream-side exhaust gas treatment unit may include the above-described catalytic converter, and the downstream-side exhaust gas treatment unit may include the above-described exhaust heat recovery device.
- a second embodiment of the invention provides an exhaust gas treatment method for an internal combustion engine.
- An exhaust passage of the internal combustion engine is configured such that exhaust gas flowing along a part of a wall face, which defines the exhaust passage at a portion upstream of a catalytic converter for purifying exhaust gas from the internal combustion engine, flows into an exhaust gas treatment unit arranged in the exhaust passage as a result of burble of exhaust gas away from the part of the wall face in an exhaust gas burble zone.
- a plasma actuator is arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, and the plasma actuator is configured to generate air current along the wall face of the exhaust passage in exhaust gas inside the exhaust passage.
- the exhaust gas treatment method includes: acquiring a temperature of the catalytic converter; and, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, inputting energy to the plasma actuator.
- a third embodiment of the invention provides an exhaust gas treatment method for an internal combustion engine.
- An exhaust passage of the internal combustion engine is configured such that exhaust gas flowing along a part of a wall face, which defines the exhaust passage at a portion upstream of a catalytic converter for purifying exhaust gas from the internal combustion engine, flows into the catalytic converter as a result of burble of exhaust gas away from the part of the wall face in an exhaust gas burble zone.
- a plasma actuator is arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, and the plasma actuator is configured to generate air current along the wall face of the exhaust passage in exhaust gas inside the exhaust passage.
- the exhaust gas treatment method includes: acquiring an exhaust gas flow rate; and causing exhaust gas to flow into the catalytic converter in a diffused state by applying larger energy to the plasma actuator as the acquired exhaust gas flow rate increases.
- the exhaust gas treatment method may further include acquiring a temperature of the catalytic converter; and, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, causing exhaust gas to flow into the catalytic converter in a diffused state.
- a sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone, taken along a flow direction of exhaust gas, may include a convex curved line.
- a cylindrical heat insulation partition surrounding a zone of part of the catalytic converter along a flow direction of exhaust gas may be provided in the catalytic converter.
- the zone surrounded by the heat insulation partition may include a zone into which exhaust gas disproportionately flows as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone.
- a fourth embodiment of the invention provides an exhaust gas treatment method for an internal combustion engine.
- the exhaust passage is branched into two by a partition wall extending along a flow direction of exhaust gas.
- An exhaust heat recovery device is arranged in one of the branched exhaust passages and configured to exchange heat between exhaust gas flowing through this branched exhaust passages and coolant of the internal combustion engine.
- An exhaust gas burble zone is provided at a portion at which the exhaust passage is branched.
- the exhaust passage is configured such that, at the time when part of exhaust gas flows into the aforementioned branched exhaust passage, the amount of exhaust gas flowing into this branched exhaust passage reduces as a result of burble of exhaust gas, flowing along a part of a wall face, which defines the exhaust passage, away from the part of the wall face.
- a plasma actuator is arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone so as to suppress burble of exhaust gas away from the wall face of the exhaust passage.
- the plasma actuator is configured to generate air current along the wall face of the exhaust passage.
- the exhaust gas treatment method includes: acquiring a temperature of coolant of the internal combustion engine; and, when the acquired temperature of coolant is lower than a temperature set in advance, facilitating flow of exhaust gas into the one of the branched exhaust passages by inputting energy to the plasma actuator.
- a clearance from a part of the wall face, which defines the aforementioned branched exhaust passage, to the partition wall along a direction perpendicular to the partition wall may be set so as to be shorter than a clearance from the part of the wall face, which defines this branched exhaust passage, to the wall face that defines the exhaust passage just before branching along the direction perpendicular to the partition wall.
- the exhaust gas treatment apparatus it is possible to cause exhaust gas to flow along the part of the wall face of the exhaust passage in the exhaust gas burble zone with the use of the plasma actuator without burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone.
- the exhaust gas treatment unit includes the catalytic converter for purifying exhaust gas
- the plasma actuator such that the amount of energy that is input to the plasma actuator increases as the acquired flow rate of exhaust gas increases.
- the length of the heat insulation partition is set so as to be shorter than the length of the catalytic converter and the upstream end of the heat insulation partition is located at the upstream end of the catalytic converter, it is possible to facilitate a warm-up of the internal combustion engine by using only the zone of the catalytic converter, surrounded by the heat insulation partition, during a warm-up. It is also possible to effectively use the entire area of the catalytic converter other than during a warm-up.
- the heat insulation partition When the heat insulation partition is an air layer, the heat insulation partition may be a simple air gap, so it is possible to extremely easily provide the heat insulation partition in the catalytic converter.
- the temperature of the zone of the catalytic converter different from the zone into which exhaust gas from the small-diameter portion is caused to flow because of the exhaust gas burble zone, is acquired, it may be estimated that the temperature of the entire passage section of the catalytic converter including that zone is higher than or equal to the activation lower limit temperature.
- the particulate filter for trapping particulate matter contained in exhaust gas is arranged downstream of the catalytic converter, it is possible to facilitate a warm-up of the catalytic converter. Moreover, because soot contained in exhaust gas is oxidized by the operation of the plasma actuator, the amount of soot contained in exhaust gas that flows into the particulate filter through the catalytic converter reduces, and it is possible to reduce the frequency of the process of regenerating the particulate filter.
- the exhaust gas treatment unit When the exhaust gas treatment unit is arranged in the aforementioned branched exhaust passage into which the exhaust passage is branched by the partition wall and the exhaust gas treatment unit includes the exhaust heat recovery device for exchanging heat between exhaust gas flowing through this branched exhaust passage and coolant of the internal combustion engine, it is possible to shorten a time that is required for a warm-up by raising the rate of rise in the temperature of coolant of the internal combustion engine.
- the upstream-side exhaust gas treatment unit includes the catalytic converter
- the downstream-side exhaust gas treatment unit includes the exhaust heat recovery device
- exhaust gas treatment method it is possible to cause exhaust gas, flowing from the exhaust gas burble zone into the catalytic converter, to flow over the entire area of the exhaust gas treatment unit by diffusing the exhaust gas without increasing passage resistance irrespective of the flow rate of the exhaust gas.
- FIG. 1 is a conceptual view of an embodiment in which the invention is applied to a vehicle on which a compression-ignition multi-cylinder internal combustion engine is mounted;
- FIG. 2 is a control block diagram of a main portion in the embodiment shown in FIG. 1 ;
- FIG. 3 is an extracted enlarged cross-sectional view of an exhaust gas treatment unit in the embodiment shown in FIG. 1 ;
- FIG. 4 is a further extracted enlarged electrical circuit configuration diagram that schematically shows part of a first exhaust gas burble zone shown in FIG. 3 ;
- FIG. 5 is a map that schematically shows the relationship between an exhaust gas flow rate and a voltage applied to a plasma actuator
- FIG. 6 is a graph that schematically shows a change in the temperature of a catalytic converter
- FIG. 7 is an extracted enlarged cross-sectional view of an exhaust gas treatment unit in another embodiment of the invention.
- FIG. 8 is a flowchart that shows the procedure of controlling the plasma actuator in the catalytic converter.
- FIG. 9 is a flowchart that shows the procedure of controlling the plasma actuator for an exhaust heat recovery device.
- an embodiment of the invention is applied to a vehicle on which a compression-ignition multi-cylinder internal combustion engine is mounted will be described in detail with reference to FIG. 1 to FIG. 9 .
- the invention is not limited to this embodiment.
- the configuration of the embodiment may be freely modified in response to a required characteristic.
- embodiments of the invention are also effective in a spark-ignition internal combustion engine that uses gasoline, alcohol, liquefied natural gas (LNG), or the like, as fuel and ignites the fuel with the use of an ignition plug.
- LNG liquefied natural gas
- FIG. 1 schematically shows a main portion of an engine system in the present embodiment.
- FIG. 2 roughly shows control blocks of the main portion.
- An exhaust gas turbocharger, an EGR device, and the like, which are typical auxiliaries of an engine 10 are omitted from FIG. 1 . It should be noted that various sensors that are required to smoothly operate the engine 10 are also partially omitted for the sake of convenience.
- the engine 10 in the present embodiment is a self-ignition, that is, compression-ignition multi-cylinder internal combustion engine that causes light oil, biofuel or composite fuel of them, as fuel, to naturally ignite by directly injecting the fuel from any one of fuel injection valves 11 into a corresponding one of combustion chambers 10 a , which is placed in a compression state.
- the engine 10 may be a single-cylinder internal combustion engine.
- a cylinder head 12 has intake ports 12 a and exhaust ports 12 b that face the corresponding combustion chambers 10 a .
- a valve actuating mechanism is incorporated in the cylinder head 12 .
- the valve actuating mechanism includes intake valves 13 and exhaust valves 14 .
- Each of the intake valves 13 opens or closes a corresponding one of the intake ports 12 a .
- Each of the exhaust valves 14 opens or closes a corresponding one of the exhaust ports 12 b .
- Each fuel injection valve 11 is provided at the center of the upper end of a corresponding one of the combustion chambers 10 a .
- Each fuel injection valve 11 is assembled to the cylinder head 12 so as to be placed between the intake valve 13 and the exhaust valve 14 .
- An intake pipe 15 is connected to the intake ports 12 a of the cylinder head 12 .
- the intake pipe 15 defines an intake passage 15 a together with the intake ports 12 a .
- An air flow meter 16 is installed at the upstream side of the intake pipe 15 .
- Information about an intake air flow rate detected by the air flow meter 16 is output to the ECU 17 .
- the air flow meter 16 is used as a flow rate acquisition device in the invention.
- an exhaust gas flow rate may be acquired from an additional air flow meter provided in an exhaust passage 18 a (described later) or may be calculated from an engine rotation speed, an intake air temperature and an intake air pressure.
- an exhaust gas flow velocity may be acquired instead of an exhaust gas flow rate.
- An ECU 17 that serves as a controller in an embodiment of the invention includes not only a known microprocessor but also a CPU, a ROM, a RAM, a nonvolatile memory, input/output interfaces, and the like, which are connected to one another via a data bus (not shown).
- the ECU 17 in the present embodiment includes an operating state determination unit 17 a .
- the operating state determination unit 17 a determines the operating state of the vehicle on the basis of information from the air flow meter 16 , various sensors (described later), and the like.
- An exhaust pipe 18 is coupled to the cylinder head 12 such that the exhaust passage 18 a communicates with the exhaust ports 12 b .
- the exhaust pipe 18 defines the exhaust passage 18 a .
- An exhaust gas control apparatus 19 and an exhaust heat recovery device 20 are arranged in order from the upstream side of the exhaust passage 18 a in the exhaust passage 18 a at a portion upstream of a muffler (not shown) arranged at the downstream end side of the exhaust passage 18 a.
- FIG. 3 shows an extracted enlarged view of a portion including the exhaust gas control apparatus 19 and the exhaust heat recovery device 20 .
- FIG. 4 shows the schematic configuration of a plasma actuator in the present embodiment.
- the exhaust gas control apparatus 19 in the present embodiment includes a diesel oxidation catalytic converter (DOC) 21 and a diesel particulate filter (DPF) 22 .
- the DOC 21 serves as a first exhaust gas treatment unit in an embodiment of the invention.
- the DPF 22 is arranged downstream of the DOC 21 .
- the DOC 21 is used to detoxify toxic substances that are produced through combustion of air-fuel mixture in the combustion chambers 10 a .
- the DPF 22 is used to trap particulate matter contained in exhaust gas.
- a catalytic converter, other than the DOC 21 or the DPF 22 may be further incorporated in the exhaust gas control apparatus 19 .
- a compact three-way catalyst is typically used as the first exhaust gas treatment unit of the invention instead of the DOC 21 .
- the first exhaust gas burble zone Z 1 is a zone in which exhaust gas flowing along a part of a wall face 18 e , which defines the exhaust passage 18 a , burbles away from the part of the wall face 18 e and, as a result, exhaust gas disproportionately flows into an upstream end face 21 a of the DOC 21 .
- the first exhaust gas burble zone Z 1 is located at the upstream end side of a cone portion 18 b in which the passage sectional area of the exhaust pipe 18 steeply increases, and the sectional shape of the part of the wall face 18 e of the exhaust passage 18 a in the first exhaust gas burble zone Z 1 , taken along the flow direction of exhaust gas, includes a convex curved line shown in FIG. 3 .
- a first plasma actuator 23 is arranged at the part of the wall face 18 e of the exhaust passage 18 a in the first exhaust gas burble zone Z 1 .
- the first plasma actuator 23 is used to generate air current toward the DOC 21 along the part of the wall face 18 e .
- the principle, basic configuration, and the like, of the first plasma actuator 23 are known in Japanese Patent Application Publication No. 2012-180799 (JP 2012-180799 A), or the like, and will be simply described below.
- the first plasma actuator 23 in the present embodiment is formed of a group of first electrodes 23 a , a group of second electrodes 23 b , a dielectric layer 23 c and an insulation layer 23 d as main components.
- the first plasma actuator 23 further includes an inverter 24 , a first switch 25 , and the like.
- the group of first electrodes 23 a are arranged at set intervals on one surface of the thin-film dielectric layer 23 c , facing toward the exhaust passage 18 a .
- the group of second electrodes 23 b are arranged at the set intervals same as the group of first electrodes 23 a on the other surface of the dielectric layer 23 c , facing toward the wall face 18 e that defines the exhaust passage 18 a .
- the insulation layer 23 d coats the group of second electrodes 23 b , and is bonded to the wall face 18 e that defines the exhaust passage 18 a .
- the group of first electrodes 23 a are coated with a thin-film insulation protection layer 23 e .
- the group of second electrodes 23 b are arranged slightly offset to the downstream side in relative position with respect to the group of first electrodes 23 a along an arrangement direction in which the groups of first and second electrodes 23 a , 23 b are arranged.
- the arrangement direction is parallel to the flow direction of exhaust gas flowing through the exhaust passage 18 a .
- the group of second electrodes 23 b are connected to the inverter 24 via the first switch 25 .
- the on/off operation of the first switch 25 that is, the on/off state of energization to the first plasma actuator 23 , is controlled by the ECU 17 .
- the first plasma actuator 23 because the thickness of the first plasma actuator 23 is extremely thin and is about several micrometers to several hundreds of micrometers, the first plasma actuator 23 installed on the wall face 18 e that defines the exhaust passage 18 a does not substantially interfere with flow of exhaust gas.
- the first plasma actuator 23 does not need to be arranged over the entire circumference of the exhaust passage 18 a in the first exhaust gas burble zone Z 1 .
- the first plasma actuator 23 may be arranged only at a portion having a particularly large curvature in the first exhaust gas burble zone Z 1 .
- the groups of electrodes 23 a , 23 b , the dielectric layer 23 c , the insulation layer 23 d , the insulation protection layer 23 e , and the like are desirably made of materials having high heat resistance.
- the electrodes may be made of iron or nickel and the dielectric layer 23 c , the insulation layer 23 d and the insulation protection layer 23 e may be made of ceramics, or the like.
- An input energy amount setting unit 17 b of the ECU 17 stores a map shown in FIG. 5 .
- the relationship between a flow rate Q of exhaust gas flowing through the exhaust passage 18 a per unit time and a voltage V 1 that is applied to the first plasma actuator 23 is set in advance in the map.
- the operation of the first plasma actuator 23 is controlled via the first switch 25 such that the amount of energy that is input to the first plasma actuator 23 increases as the exhaust gas flow rate Q increases.
- the input energy amount setting unit 17 b sets the voltage V 1 that is applied to the first plasma actuator 23 , as the amount of energy that is input to the first plasma actuator 23 , on the basis of information from the above-described air flow meter 16 .
- the inverter 24 is supplied with electric power from an in-vehicle secondary battery 26 .
- the inverter 24 is able to change the output voltage, for example, within the range of about 1 to 10 kV.
- the inverter 24 applies the voltage V 1 , set by the input energy amount setting unit 17 b , to the first plasma actuator 23 at a predetermined driving frequency via the first switch 25 , of which the on/off state is controlled by the ECU 17 .
- the amount of input energy is controlled by changing the voltage V that is applied to the first plasma actuator 23 in the present embodiment.
- the amount of input energy may be controlled by changing both the applied voltage V 1 and the driving frequency or a similar advantageous effect may be obtained by applying direct-current pulse voltage to the first plasma actuator 23 .
- soot contained in exhaust gas is oxidized by the operation of the first plasma actuator 23 , so it is possible to further reduce the amount of soot contained in exhaust gas flowing into the DPF 22 through the DOC 21 . As a result, it is possible to reduce the frequency of the process of regenerating the DPF 22 .
- a catalyst temperature sensor 27 is attached to the DOC 21 as a temperature acquisition device configured to acquire the temperature of a catalytic converter according to an embodiment of the invention.
- Information about the temperature of the DOC 21 , acquired by the catalyst temperature sensor 27 is output to the ECU 17 .
- the ECU 17 applies the high voltage V 1 to the first plasma actuator 23 by switching the first switch 25 to an energized state only when the temperature T C of the DOC 21 is higher than or equal to an activation lower limit temperature T CL of the DOC 21 and the temperature T C of the DOC 21 is lower than or equal to an upper limit temperature T CH of the DOC 21 .
- the temperature T C of the DOC 21 is desirably the temperature of a zone different from a zone into which exhaust gas flows because of the first exhaust gas burble zone Z 1 , that is, a zone into which exhaust gas is difficult to flow.
- the temperature of an outer peripheral end of the DOC 21 at a portion downstream of a heat insulation partition 21 b (described later) is acquired.
- an exhaust gas temperature sensor for detecting an exhaust gas temperature may be arranged at at least one of a portion upstream of the exhaust gas control apparatus 19 and a portion downstream of the exhaust gas control apparatus 19 , and the temperature T C of the DOC 21 may be estimated on the basis of detected information from the exhaust gas temperature sensor.
- a temporal change in the temperature T C of the DOC 21 from the start of a warm-up may be obtained in advance by an experiment, and the temperature T C of the DOC 21 may be estimated on the basis of a time from the start of the warm-up.
- the cylindrical heat insulation partition 21 b made of a heat-resistant material having a lower thermal conductivity than air, such as Porextherm WDS (trademark) produced by Kurosaki Harima Corporation, is provided at the upstream end of the DOC 21 in the DOC 21 in the present embodiment.
- the heat insulation partition 21 b may be an air layer. In this case, a cylindrical air gap just needs to be provided in the DOC 21 .
- the zone surrounded by the cylindrical heat insulation partition 21 b is a zone in which exhaust gas disproportionately flows into the DOC 21 as a result of burble of exhaust gas in the first exhaust gas burble zone Z 1 in a state where the first plasma actuator 23 is not operated.
- the passage sectional area of the heat insulation partition 21 b is substantially equal to or slightly larger than the passage sectional area of the exhaust pipe 18 that is connected to the cone portion 18 b in the first exhaust gas burble zone Z 1 , and the outline shape of the heat insulation partition 21 b is similar to the sectional shape of the exhaust pipe 18 .
- the first plasma actuator 23 it is possible to guide the major portion of exhaust gas to the zone of the DOC 21 , surrounded by the heat insulation partition 21 b .
- the length of the heat insulation partition 21 b along the longitudinal direction of the DOC 21 is desirably smaller than or equal to a half of the DOC 21 and may be about one-third or one quarter of the DOC 21 .
- FIG. 6 schematically shows the temperature rise characteristic of the DOC 21 according to the present embodiment during a warm-up of the engine 10 .
- the continuous line in FIG. 6 indicates a temperature change at the center portion of the upstream end face 21 a of the DOC 21 , surrounded by the heat insulation partition 21 b , in a state where the first plasma actuator 23 is not operated.
- the dashed line in FIG. 6 indicates a temperature change at the center portion of the upstream end of the DOC 21 in the case where the heat insulation partition 21 b is not provided in a state where the first plasma actuator 23 is not operated.
- FIG. 6 indicates a temperature change at the center portion of the upstream end face 21 a in the case where exhaust gas flows into the DOC 21 in the case where the heat insulation partition 21 b is not provided in a state where exhaust gas is diffused by operating the first plasma actuator 23 .
- the dotted line in FIG. 6 indicates a temperature change of a zone of which the temperature is detected by the catalyst temperature sensor 27 in the present embodiment.
- the temperature of the center portion of the DOC 21 reaches the catalyst activation lower limit temperature T CL at time t 1 . It is understood that the center portion of the DOC 21 is heated to the catalyst activation lower limit temperature TLC in a period of time shorter than or equal to half of a time that is taken in the case indicated by the dashed line where the heat insulation partition 21 b is not provided and the corresponding time is t 2 . Therefore, by providing the heat insulation partition 21 b and stopping the operation of the first plasma actuator 23 during a warm-up, it is possible to improve purification of exhaust gas during a warm-up of the engine 10 by further quickly activating only the center portion of the DOC 21 .
- the temperature T C that is detected by the catalyst temperature sensor 27 that is, the temperature of the outer peripheral end of the DOC 21 , steeply rises after time t 3 at which the temperature of the outer peripheral end of the DOC 21 reaches the catalyst activation lower limit temperature T CL from time t 0 at which the engine 10 is started.
- the first plasma actuator 23 begins to operate at time t 3 at which the temperature of the outer peripheral end of the DOC 21 has reached the catalyst activation lower limit temperature T CL and exhaust gas flows into the DOC 21 in a diffused state. That is, by operating the first plasma actuator 23 at time t 3 at which the acquired temperature T C of the DOC 21 has reached the catalyst activation lower limit temperature T CL , it is possible to further early effectively cause the whole DOC 21 to function.
- the position of the heat insulation partition 21 b with respect to the DOC 21 may significantly deviate from the center portion of the DOC 21 , which is described in the case of the present embodiment, because of the shape of the cone portion 18 b , an angle at which the exhaust pipe 18 is connected to the cone portion 18 b , and the like.
- the temperature T C of the DOC 21 which is acquired by the above-described catalyst temperature sensor 27 , is desirably the temperature of the zone at the outer peripheral end of the upstream end face 21 a of the DOC 21 .
- FIG. 7 shows the sectional structure of such a first exhaust gas treatment unit according to another embodiment.
- the catalyst temperature sensor 27 is attached to the outer peripheral end of the upstream end face 21 a of the DOC 21 at a portion farthest from the exhaust pipe 18 that is connected to the cone portion 18 b .
- the first plasma actuator 23 is installed in the first exhaust gas burble zone Z 1 having a convex curved face of a zone in which the exhaust pipe 18 is connected to the cone portion 18 b .
- the heat insulation partition 21 b may be provided at a portion indicated by the alternate long and two-short dashes line in FIG. 7 , and may be provided as an air gap as described above.
- step S 11 it is determined whether the catalyst temperature T C is higher than or equal to the catalyst activation lower limit temperature T CL .
- the catalyst temperature T C is higher than or equal to the catalyst activation lower limit temperature T CL , that is, when it is determined that the catalyst temperature T C is a temperature at which there is a possibility that the first plasma actuator 23 is allowed to be operated, the process proceeds to step S 12 .
- step S 12 it is determined whether the catalyst temperature T C is lower than or equal to the upper limit temperature T CH .
- step S 13 the exhaust gas flow rate Q is acquired.
- step S 14 the applied voltage V 1 corresponding to the acquired exhaust gas flow rate Q is set.
- step S 15 the first plasma actuator 23 is driven at the set applied voltage V 1 .
- step S 16 it is determined in step S 16 whether a first flag is set. However, because the first flag is not set at first, the process proceeds to step S 17 . In step S 17 , the first flag is set, and then the process returns to step S 11 again.
- step S 11 when it is determined in step S 11 that the catalyst temperature T C is lower than the catalyst activation lower limit temperature T CL , that is, when it is desirable to quickly raise the temperature of the zone of the DOC 21 , surrounded by the heat insulation partition 21 b , the process proceeds to step S 18 .
- step S 12 As in the case where it is determined in step S 12 that the catalyst temperature T C is higher than the upper limit temperature T CH , the process proceeds to step S 18 .
- step S 18 it is determined whether the first flag is set. When it is determined that the first flag is set, the operation of the first plasma actuator 23 is stopped by setting the applied voltage V 1 to zero in step S 19 , the first flag is reset in step S 20 , and then the process returns to step S 11 again. Thus, it is possible to avoid supplying unnecessary electric power to the first plasma actuator 23 .
- step S 11 When it is determined in step S 11 that the catalyst temperature T C is lower than the catalyst activation lower limit temperature T CL , the operation of the first plasma actuator 23 is stopped. Thus, exhaust gas disproportionately flows from the first exhaust gas burble zone Z 1 into the zone surrounded by the heat insulation partition 21 b of the DOC 21 . As a result, it is possible to further quickly raise the temperature of the zone surrounded by the heat insulation partition 21 b of the DOC 21 to the activation lower limit temperature T CL or higher, so it is possible to facilitate purification of exhaust gas during a warm-up of the engine 10 .
- a swelled portion 28 is provided in the exhaust pipe 18 downstream of the exhaust gas control apparatus 19 .
- the swelled portion 28 has an increased passage sectional area.
- a partition wall 29 is arranged in the exhaust passage 18 a .
- the partition wall 29 extends along the flow direction of exhaust gas so as to partition off a space in the swelled portion 28 .
- An inlet portion 28 a is provided between the upstream end of the partition wall 29 and the wall face 18 e that defines the swelled portion 28 of the exhaust pipe 18 .
- An outlet portion 28 b is provided between the downstream end of the partition wall 29 and the wall face 18 e that defines the swelled portion 28 of the exhaust pipe 18 .
- the inlet portion 28 a is used to cause exhaust gas to flow into the swelled portion 28 side.
- the outlet portion 28 b is used to cause exhaust gas in the swelled portion 28 to flow out.
- the exhaust passage 18 a downstream of the exhaust gas control apparatus 19 is branched into a main exhaust passage 18 c and an auxiliary exhaust passage 18 d .
- the main exhaust passage 18 c is not bypassed to the swelled portion 28 .
- the auxiliary exhaust passage 18 d is bypassed to the swelled portion 28 .
- the exhaust heat recovery device 20 communicates with a water jacket 30 a provided in a cylinder block 30 .
- the exhaust heat recovery device 20 is arranged in the auxiliary exhaust passage 18 d , and exchanges heat between exhaust gas flowing through the auxiliary exhaust passage 18 d and coolant of the engine 10 .
- the exhaust heat recovery device 20 serves as a second exhaust gas treatment unit of the invention.
- the exhaust heat recovery device 20 is used to achieve an early warm-up of the engine 10 by raising the temperature of coolant by the use of heat of exhaust gas.
- the above-described DPF 22 may be arranged in the exhaust passage 18 a at a portion downstream of the exhaust heat recovery device 20 . In this case, it is possible to further efficiently recover exhaust heat.
- FIG. 3 there is a second exhaust gas burble zone Z 2 in which exhaust gas flowing along a part of the wall face 18 e , which defines an upstream branching zone of the swelled portion 28 , burbles away from the part of the wall face 18 e and, as a result, the amount of exhaust gas flowing into the swelled portion 28 is reduced.
- a second plasma actuator 31 is arranged at the part of the wall face 18 e of the exhaust passage 18 a in the second exhaust gas burble zone Z 2 .
- the sectional shape of the second exhaust gas burble zone Z 2 taken along the flow direction of exhaust gas, includes a convex curved line.
- the second plasma actuator 31 is used to generate air current toward the exhaust heat recovery device 20 along the part of the wall face 18 e .
- the second plasma actuator 31 basically has the same configuration as the above-described first plasma actuator 23 , and is connected to the inverter 24 via a second switch 32 .
- the on/off state of the second switch 32 is controlled by the ECU 17 .
- an applied voltage V 2 , a driving frequency, and the like, to the second plasma actuator 31 by the inverter 24 are constant values set in advance in response to the curvature of the second exhaust gas burble zone Z 2 .
- a clearance W 1 from a part of a wall face 28 c of the swelled portion 28 , which defines the auxiliary exhaust passage 18 d , to the partition wall 29 along a direction perpendicular to the partition wall 29 is set so as to be shorter than a clearance W 2 from the same wall face 28 c to a part of the wall face 28 e , which defines the exhaust passage 18 a just before branching along the direction perpendicular to the partition wall 29 .
- a distance from the center of the main exhaust passage 18 c to the wall face 18 e that defines the exhaust passage 18 a just before branching is set so as to be shorter than a distance from the center of the main exhaust passage 18 c to the partition wall 29 .
- a mechanical shutter mechanism for opening or closing the outlet portion 28 b may be incorporated.
- component cost, maintenance, and the like are required for incorporating a mechanical shutter mechanism.
- reliability is high, and it is possible to reduce component cost and pressure loss.
- a coolant temperature sensor 33 is arranged in the cylinder block 30 .
- the coolant temperature sensor 33 acquires the temperature T W of coolant of the engine 10 and outputs the detected information to the ECU 17 .
- the coolant of the engine 10 flows through the water jacket 30 a .
- the ECU 17 operates the second plasma actuator 31 by switching the second switch 32 to the energized state only when the acquired temperature T W of coolant is lower than a temperature T WL set in advance.
- step S 21 it is determined whether the coolant temperature T W is lower than the lower limit coolant temperature T WL .
- the second plasma actuator 31 is driven in step S 22 .
- step S 23 it is determined whether a second flag is set. Because the second flag is not set at first, the process proceeds to step S 24 . In step S 24 , the second flag is set, and then the process returns to step S 21 again.
- step S 21 When it is determined in step S 21 that the coolant temperature T W is higher than or equal to the lower limit coolant temperature T WL , that is, when a warm-up of the engine 10 has completed, the process proceeds to step S 25 .
- step S 25 it is determined whether the second flag is set. When it is determined that the second flag is set, that is, when electric power is being supplied to the second plasma actuator 31 , the process proceeds to step S 26 . The operation of the second plasma actuator 31 is stopped by setting the voltage V 2 , applied to the second plasma actuator 31 , to zero in step S 26 . After that, the process proceeds to step S 27 , the second flag is reset, and the process returns to step S 21 again.
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Abstract
An exhaust gas treatment apparatus for an internal combustion engine includes: an exhaust gas treatment unit arranged in an exhaust passage of the internal combustion engine, the exhaust passage being configured such that i) exhaust gas flowing along a part of a wall face, which defines the exhaust passage, burbles away from the part of the wall face in an exhaust gas burble zone and ii) as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone, exhaust gas disproportionately flows into the exhaust gas treatment unit or the amount of exhaust gas flowing into the exhaust gas treatment unit reduces. A plasma actuator is also provided arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, the plasma actuator being configured to generate air current toward the exhaust gas treatment unit along the part of the wall face in exhaust gas inside the exhaust passage.
Description
- The disclosure of Japanese Patent Application No. 2015-054855 filed on Mar. 18, 2015 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
- 1. Field of the Invention
- Embodiments of the present invention relate to an apparatus and method for treating exhaust gas that is emitted from an internal combustion engine.
- 2. Description of Related Art
- If a vehicle is intended to be downsized, installation space for auxiliaries that are mounted on the vehicle is subjected to constraints, and various piping paths, and the like, should be significantly bent. For example, an exhaust gas turbine of a supercharger, a catalytic converter of an exhaust gas control apparatus, a muffler, and the like, are closely arranged in an exhaust passage that guides exhaust gas that is emitted from an internal combustion engine mounted on a vehicle, so an exhaust pipe that connects these devices needs to be significantly bent.
- Incidentally, the passage sectional area of the catalytic converter of the exhaust gas control apparatus may be about several times as large as the passage sectional area of the exhaust pipe for the purpose of increasing exhaust gas purification efficiency. In order to maximally utilize the purification performance of such a catalytic converter, it is required to decrease the space velocity of exhaust gas by diffusing exhaust gas, which flows into the catalytic converter, over the entire area of an end face of the catalytic converter. Therefore, a large-diameter casing that accommodates the catalytic converter and a small-diameter exhaust pipe that is connected to the casing are coupled to each other via a tapered member called a cone for diffusing exhaust gas.
- However, with the above-described downsizing of the vehicle, the length of the tapered member tends to be extremely short. The flow direction of exhaust gas that passes through the catalytic converter often significantly differs from the flow direction of exhaust gas that flows from the exhaust pipe into the tapered member. In such a case, exhaust gas that flows along a wall face of the exhaust passage from the small-diameter exhaust pipe to the catalytic converter via the tapered member burbles away from the wall face of the exhaust passage at the connection point at which the exhaust pipe is connected to the tapered member. As a result, exhaust gas that passes through the tapered member flows into only the zone of part of the catalytic converter without diffusing so much, with the result that it is not possible to maximally utilize the purification performance of the catalytic converter.
- In order to solve such an inconvenience, a technique for forcibly distributing the flow direction of exhaust gas by incorporating a louver in an exhaust pipe on the inlet side of the catalytic converter has been suggested in Japanese Patent Application Publication No. 2012-193719 (JP 2012-193719 A).
- When a louver member as described in JP 2012-193719 A is incorporated in the exhaust passage, passage resistance increases and, in addition, the louver member absorbs heat of exhaust gas at the time of a warm-up of the internal combustion engine, with the result that the time to complete a warm-up is extended. This leads to deterioration of fuel economy.
- Embodiments of the present invention provide an exhaust gas treatment apparatus and exhaust gas treatment method that are able to diffuse exhaust gas over the entire area of a catalytic converter without increasing passage resistance as described in JP 2012-193719 A even with a configuration where the flow direction of exhaust gas from an exhaust pipe to the catalytic converter steeply bends.
- An embodiment of the present invention also provides an exhaust gas treatment apparatus and exhaust gas treatment method that, even when the amount of exhaust gas flowing into an exhaust gas treatment unit tends to reduce because of steep bending of an exhaust pipe, is able to prevent at least a reduction in the amount of exhaust gas flowing into the exhaust gas treatment unit without increasing passage resistance.
- A first embodiment of the invention provides an exhaust gas treatment apparatus for an internal combustion engine. The exhaust gas treatment apparatus includes: an exhaust gas treatment unit arranged in an exhaust passage of the internal combustion engine, the exhaust passage being configured such that i) exhaust gas flowing along a part of a wall face, which defines the exhaust passage, burbles away from the part of the wall face in an exhaust gas burble zone and ii) as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone, exhaust gas disproportionately flows into the exhaust gas treatment unit or the amount of exhaust gas flowing into the exhaust gas treatment unit reduces. A plasma actuator is provided arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, the plasma actuator being configured to generate air current toward the exhaust gas treatment unit along the part of the wall face in exhaust gas inside the exhaust passage.
- In embodiments of the invention, when the plasma actuator operates, air current is generated toward the exhaust gas treatment unit along the part of the wall face of the exhaust passage in the exhaust gas burble zone. Thus, exhaust gas flowing along the part of the wall face of the exhaust passage in the exhaust gas burble zone is dragged by the air current, flows without burbling away from the part of the wall face of the exhaust passage, and then flows into the exhaust gas treatment unit in a diffused state or a reduction in the amount of exhaust gas flowing into the exhaust gas treatment unit is suppressed.
- In the exhaust gas treatment apparatus according to embodiments of the invention, a sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone, taken along a flow direction of exhaust gas, may include a convex curved line.
- The exhaust gas treatment apparatus may further include a flow rate acquisition device configured to acquire a flow rate of exhaust gas flowing through the exhaust passage; and a controller configured to control the amount of energy that is input to the plasma actuator. The exhaust gas treatment unit may include a catalytic converter configured to purify exhaust gas, and the controller may be configured to control the plasma actuator such that the amount of energy that is input to the plasma actuator increases as the acquired flow rate of exhaust gas increases. In this case, the exhaust gas treatment apparatus may further include a temperature acquisition device configured to acquire a temperature of the catalytic converter, and the controller may be configured to, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, input energy to the plasma actuator. A mode of controlling the amount of energy that is input to the plasma actuator may include changing an applied voltage or a driving frequency.
- The exhaust gas treatment unit may include a catalytic converter configured to purify exhaust gas, the exhaust gas treatment apparatus may further include a temperature acquisition device configured to acquire a temperature of the catalytic converter; and a controller configured to control the amount of energy that is input to the plasma actuator, and the controller may be configured to, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, input energy to the plasma actuator.
- The controller may be configured to, when the acquired temperature of the catalytic converter is lower than or equal to an upper limit temperature of the catalytic converter, input energy to the plasma actuator. The upper limit temperature of the catalytic converter means a maximum temperature at or below which degradation, dissolution loss, or the like, of the catalytic converter due to heat does not occur. Therefore, it may be understood that degradation, dissolution loss, or the like, of the catalytic converter begins when the temperature exceeds the upper limit temperature.
- A cylindrical heat insulation partition surrounding a zone of part of the catalytic converter along a flow direction of exhaust gas may be provided in the catalytic converter. The zone surrounded by the heat insulation partition may include a zone into which exhaust gas disproportionately flows as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone. When the acquired temperature of the catalytic converter is lower than an activation lower limit temperature of the catalytic converter, a major portion of exhaust gas may be guided to the zone surrounded by the heat insulation partition. In this case, the length of the heat insulation partition along the flow direction of exhaust gas may be shorter than the length of the catalytic converter along the flow direction of exhaust gas, and an upstream end of the heat insulation partition along the flow direction of exhaust gas may be located at an upstream end of the catalytic converter along the flow direction of exhaust gas.
- In this specification, the word “upstream” or “upstream side” means a side closer to a combustion chamber of the internal combustion engine; whereas, the word “downstream” or “downstream side” means a side away from the combustion chamber of the internal combustion engine.
- The heat insulation partition may be an air layer.
- The acquired temperature of the catalytic converter may be a temperature of a zone different from a zone into which exhaust gas from a small-diameter portion flows because of the exhaust gas burble zone.
- The exhaust gas treatment apparatus may further include a particulate filter configured to trap particulate matter contained in exhaust gas, and the particulate filter may be arranged downstream of the catalytic converter.
- The exhaust passage may be branched into two by a partition wall extending along a flow direction of exhaust gas, and the exhaust gas treatment unit may include an exhaust heat recovery device arranged in one of the branched exhaust passages and configured to exchange heat between exhaust gas flowing through this branched exhaust passages and coolant of the internal combustion engine. In this case, the exhaust gas burble zone may be located at a portion at which the exhaust passage is branched, and the exhaust passage may be configured such that the amount of exhaust gas flowing into the branched exhaust passage mentioned above reduces as a result of burble of exhaust gas away from a part of a wall face of the exhaust passage in the exhaust gas burble zone. The exhaust gas treatment apparatus may further include a coolant temperature sensor configured to acquire a temperature of coolant of the internal combustion engine, and the controller may be configured to, when the acquired temperature of coolant is lower than a temperature set in advance, input energy to the plasma actuator.
- A clearance from a part of the wall face, which defines the aforementioned branched exhaust passage, to the partition wall along a direction perpendicular to the partition wall may be set so as to be shorter than a clearance from the part of the wall face, which defines this branched exhaust passage, to the wall face that defines the exhaust passage just before branching along the direction perpendicular to the partition wall.
- A plurality of the exhaust gas treatment units may be arranged in series along the exhaust passage, the upstream-side exhaust gas treatment unit may include the above-described catalytic converter, and the downstream-side exhaust gas treatment unit may include the above-described exhaust heat recovery device.
- A second embodiment of the invention provides an exhaust gas treatment method for an internal combustion engine. An exhaust passage of the internal combustion engine is configured such that exhaust gas flowing along a part of a wall face, which defines the exhaust passage at a portion upstream of a catalytic converter for purifying exhaust gas from the internal combustion engine, flows into an exhaust gas treatment unit arranged in the exhaust passage as a result of burble of exhaust gas away from the part of the wall face in an exhaust gas burble zone. A plasma actuator is arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, and the plasma actuator is configured to generate air current along the wall face of the exhaust passage in exhaust gas inside the exhaust passage. The exhaust gas treatment method includes: acquiring a temperature of the catalytic converter; and, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, inputting energy to the plasma actuator.
- A third embodiment of the invention provides an exhaust gas treatment method for an internal combustion engine. An exhaust passage of the internal combustion engine is configured such that exhaust gas flowing along a part of a wall face, which defines the exhaust passage at a portion upstream of a catalytic converter for purifying exhaust gas from the internal combustion engine, flows into the catalytic converter as a result of burble of exhaust gas away from the part of the wall face in an exhaust gas burble zone. A plasma actuator is arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, and the plasma actuator is configured to generate air current along the wall face of the exhaust passage in exhaust gas inside the exhaust passage. The exhaust gas treatment method includes: acquiring an exhaust gas flow rate; and causing exhaust gas to flow into the catalytic converter in a diffused state by applying larger energy to the plasma actuator as the acquired exhaust gas flow rate increases.
- The exhaust gas treatment method according to the third embodiment of the invention may further include acquiring a temperature of the catalytic converter; and, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, causing exhaust gas to flow into the catalytic converter in a diffused state.
- A sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone, taken along a flow direction of exhaust gas, may include a convex curved line.
- A cylindrical heat insulation partition surrounding a zone of part of the catalytic converter along a flow direction of exhaust gas may be provided in the catalytic converter. The zone surrounded by the heat insulation partition may include a zone into which exhaust gas disproportionately flows as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone.
- A fourth embodiment of the invention provides an exhaust gas treatment method for an internal combustion engine. The exhaust passage is branched into two by a partition wall extending along a flow direction of exhaust gas. An exhaust heat recovery device is arranged in one of the branched exhaust passages and configured to exchange heat between exhaust gas flowing through this branched exhaust passages and coolant of the internal combustion engine. An exhaust gas burble zone is provided at a portion at which the exhaust passage is branched. The exhaust passage is configured such that, at the time when part of exhaust gas flows into the aforementioned branched exhaust passage, the amount of exhaust gas flowing into this branched exhaust passage reduces as a result of burble of exhaust gas, flowing along a part of a wall face, which defines the exhaust passage, away from the part of the wall face. A plasma actuator is arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone so as to suppress burble of exhaust gas away from the wall face of the exhaust passage. The plasma actuator is configured to generate air current along the wall face of the exhaust passage. The exhaust gas treatment method includes: acquiring a temperature of coolant of the internal combustion engine; and, when the acquired temperature of coolant is lower than a temperature set in advance, facilitating flow of exhaust gas into the one of the branched exhaust passages by inputting energy to the plasma actuator.
- In the exhaust gas treatment method according to the fourth embodiment of the invention, a clearance from a part of the wall face, which defines the aforementioned branched exhaust passage, to the partition wall along a direction perpendicular to the partition wall may be set so as to be shorter than a clearance from the part of the wall face, which defines this branched exhaust passage, to the wall face that defines the exhaust passage just before branching along the direction perpendicular to the partition wall.
- With the exhaust gas treatment apparatus according to embodiments of the invention, it is possible to cause exhaust gas to flow along the part of the wall face of the exhaust passage in the exhaust gas burble zone with the use of the plasma actuator without burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone. As a result, it is possible to diffuse exhaust gas flowing from the exhaust gas burble zone into the exhaust gas treatment unit and cause the exhaust gas to flow over the entire area of the exhaust gas treatment unit without increasing passage resistance. Alternatively, it is possible to suppress or prevent a reduction in the amount of exhaust gas flowing into the exhaust gas treatment unit or increase the amount of exhaust gas flowing into the exhaust gas treatment unit.
- When the sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone in which the plasma actuator is arranged, taken along the flow direction of exhaust gas, includes a convex curved line, an advantageous effect of embodiments of the invention may be remarkably obtained.
- When the exhaust gas treatment unit includes the catalytic converter for purifying exhaust gas, it is possible to cause exhaust gas to constantly flow over the entire area of the catalytic converter by controlling the plasma actuator such that the amount of energy that is input to the plasma actuator increases as the acquired flow rate of exhaust gas increases.
- By inputting energy to the plasma actuator only when the acquired temperature of the catalytic converter is higher than or equal to the activation lower limit temperature of the catalytic converter, it is possible to avoid unnecessary energy consumption of the plasma actuator. Moreover, it is possible to facilitate purification of exhaust gas during a warm-up of the internal combustion engine by further quickly raising the temperature of part of the catalytic converter to the activation lower limit temperature or higher.
- By inputting energy to the plasma actuator only when the acquired temperature of the catalytic converter is lower than or equal to the upper limit temperature of the catalytic converter, it is possible to avoid unnecessary energy consumption of the plasma actuator.
- By guiding the major portion of exhaust gas to the zone of the catalytic converter, surrounded by the heat insulation partition, only when the temperature of the catalytic converter is lower than the activation lower limit temperature of the catalytic converter, it is possible to avoid unnecessary energy consumption of the plasma actuator. Moreover, it is possible to facilitate purification of exhaust gas during a warm-up of the internal combustion engine by further quickly raising the temperature of part of the catalytic converter to the activation lower limit temperature or higher.
- When the length of the heat insulation partition is set so as to be shorter than the length of the catalytic converter and the upstream end of the heat insulation partition is located at the upstream end of the catalytic converter, it is possible to facilitate a warm-up of the internal combustion engine by using only the zone of the catalytic converter, surrounded by the heat insulation partition, during a warm-up. It is also possible to effectively use the entire area of the catalytic converter other than during a warm-up.
- When the heat insulation partition is an air layer, the heat insulation partition may be a simple air gap, so it is possible to extremely easily provide the heat insulation partition in the catalytic converter.
- When the temperature of the zone of the catalytic converter, different from the zone into which exhaust gas from the small-diameter portion is caused to flow because of the exhaust gas burble zone, is acquired, it may be estimated that the temperature of the entire passage section of the catalytic converter including that zone is higher than or equal to the activation lower limit temperature.
- When the particulate filter for trapping particulate matter contained in exhaust gas is arranged downstream of the catalytic converter, it is possible to facilitate a warm-up of the catalytic converter. Moreover, because soot contained in exhaust gas is oxidized by the operation of the plasma actuator, the amount of soot contained in exhaust gas that flows into the particulate filter through the catalytic converter reduces, and it is possible to reduce the frequency of the process of regenerating the particulate filter.
- When the exhaust gas treatment unit is arranged in the aforementioned branched exhaust passage into which the exhaust passage is branched by the partition wall and the exhaust gas treatment unit includes the exhaust heat recovery device for exchanging heat between exhaust gas flowing through this branched exhaust passage and coolant of the internal combustion engine, it is possible to shorten a time that is required for a warm-up by raising the rate of rise in the temperature of coolant of the internal combustion engine.
- By inputting energy to the plasma actuator when the acquired temperature of coolant is lower than the temperature set in advance, it is possible to avoid unnecessary energy consumption of the plasma actuator.
- When the clearance from a part of the wall face, which defines the aforementioned branched exhaust passage, to the partition wall is set so as to be shorter than the clearance from the part of the wall face, which defines this branched exhaust passage, to the wall face that defines the exhaust passage just before branching, it is possible to make part of exhaust gas difficult to flow into the exhaust heat recovery device side after completion of a warm-up of the internal combustion engine. Thus, it is possible to suppress an unnecessary rise in the temperature of coolant.
- When the plurality of the exhaust gas treatment units are arranged in series along the exhaust passage, the upstream-side exhaust gas treatment unit includes the catalytic converter, and the downstream-side exhaust gas treatment unit includes the exhaust heat recovery device, so it is possible to achieve both early activation of the catalytic converter and early completion of a warm-up during a warm-up of the internal combustion engine.
- With the exhaust gas treatment method according to the second embodiment of the invention, energy is input to the plasma actuator when the temperature of the catalytic converter is higher than or equal to the activation lower limit temperature, so it is possible to suppress unnecessary energy consumption.
- With the exhaust gas treatment method according to the third embodiment of the invention, it is possible to cause exhaust gas, flowing from the exhaust gas burble zone into the catalytic converter, to flow over the entire area of the exhaust gas treatment unit by diffusing the exhaust gas without increasing passage resistance irrespective of the flow rate of the exhaust gas.
- With the exhaust gas treatment method according to the fourth embodiment of the invention, energy is input to the plasma actuator when the temperature of coolant is low, so it is possible to shorten a time that is required to warm-up the internal combustion engine by raising the rate of rise in the temperature of coolant.
- Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
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FIG. 1 is a conceptual view of an embodiment in which the invention is applied to a vehicle on which a compression-ignition multi-cylinder internal combustion engine is mounted; -
FIG. 2 is a control block diagram of a main portion in the embodiment shown inFIG. 1 ; -
FIG. 3 is an extracted enlarged cross-sectional view of an exhaust gas treatment unit in the embodiment shown inFIG. 1 ; -
FIG. 4 is a further extracted enlarged electrical circuit configuration diagram that schematically shows part of a first exhaust gas burble zone shown inFIG. 3 ; -
FIG. 5 is a map that schematically shows the relationship between an exhaust gas flow rate and a voltage applied to a plasma actuator; -
FIG. 6 is a graph that schematically shows a change in the temperature of a catalytic converter; -
FIG. 7 is an extracted enlarged cross-sectional view of an exhaust gas treatment unit in another embodiment of the invention; -
FIG. 8 is a flowchart that shows the procedure of controlling the plasma actuator in the catalytic converter; and -
FIG. 9 is a flowchart that shows the procedure of controlling the plasma actuator for an exhaust heat recovery device. - An embodiment in which an embodiment of the invention is applied to a vehicle on which a compression-ignition multi-cylinder internal combustion engine is mounted will be described in detail with reference to
FIG. 1 toFIG. 9 . However, the invention is not limited to this embodiment. The configuration of the embodiment may be freely modified in response to a required characteristic. For example, embodiments of the invention are also effective in a spark-ignition internal combustion engine that uses gasoline, alcohol, liquefied natural gas (LNG), or the like, as fuel and ignites the fuel with the use of an ignition plug. -
FIG. 1 schematically shows a main portion of an engine system in the present embodiment.FIG. 2 roughly shows control blocks of the main portion. An exhaust gas turbocharger, an EGR device, and the like, which are typical auxiliaries of anengine 10, are omitted fromFIG. 1 . It should be noted that various sensors that are required to smoothly operate theengine 10 are also partially omitted for the sake of convenience. - The
engine 10 in the present embodiment is a self-ignition, that is, compression-ignition multi-cylinder internal combustion engine that causes light oil, biofuel or composite fuel of them, as fuel, to naturally ignite by directly injecting the fuel from any one offuel injection valves 11 into a corresponding one ofcombustion chambers 10 a, which is placed in a compression state. However, in view of the characteristic of the invention, theengine 10 may be a single-cylinder internal combustion engine. - A
cylinder head 12 hasintake ports 12 a andexhaust ports 12 b that face the correspondingcombustion chambers 10 a. A valve actuating mechanism is incorporated in thecylinder head 12. The valve actuating mechanism includesintake valves 13 andexhaust valves 14. Each of theintake valves 13 opens or closes a corresponding one of theintake ports 12 a. Each of theexhaust valves 14 opens or closes a corresponding one of theexhaust ports 12 b. Eachfuel injection valve 11 is provided at the center of the upper end of a corresponding one of thecombustion chambers 10 a. Eachfuel injection valve 11 is assembled to thecylinder head 12 so as to be placed between theintake valve 13 and theexhaust valve 14. - An
intake pipe 15 is connected to theintake ports 12 a of thecylinder head 12. Theintake pipe 15 defines anintake passage 15 a together with theintake ports 12 a. Anair flow meter 16 is installed at the upstream side of theintake pipe 15. Information about an intake air flow rate detected by theair flow meter 16 is output to theECU 17. In the present embodiment, theair flow meter 16 is used as a flow rate acquisition device in the invention. Instead, an exhaust gas flow rate may be acquired from an additional air flow meter provided in anexhaust passage 18 a (described later) or may be calculated from an engine rotation speed, an intake air temperature and an intake air pressure. Alternatively, an exhaust gas flow velocity may be acquired instead of an exhaust gas flow rate. - An
ECU 17 that serves as a controller in an embodiment of the invention includes not only a known microprocessor but also a CPU, a ROM, a RAM, a nonvolatile memory, input/output interfaces, and the like, which are connected to one another via a data bus (not shown). TheECU 17 in the present embodiment includes an operatingstate determination unit 17 a. The operatingstate determination unit 17 a determines the operating state of the vehicle on the basis of information from theair flow meter 16, various sensors (described later), and the like. - An
exhaust pipe 18 is coupled to thecylinder head 12 such that theexhaust passage 18 a communicates with theexhaust ports 12 b. Theexhaust pipe 18 defines theexhaust passage 18 a. An exhaustgas control apparatus 19 and an exhaustheat recovery device 20 are arranged in order from the upstream side of theexhaust passage 18 a in theexhaust passage 18 a at a portion upstream of a muffler (not shown) arranged at the downstream end side of theexhaust passage 18 a. -
FIG. 3 shows an extracted enlarged view of a portion including the exhaustgas control apparatus 19 and the exhaustheat recovery device 20.FIG. 4 shows the schematic configuration of a plasma actuator in the present embodiment. - The exhaust
gas control apparatus 19 in the present embodiment includes a diesel oxidation catalytic converter (DOC) 21 and a diesel particulate filter (DPF) 22. TheDOC 21 serves as a first exhaust gas treatment unit in an embodiment of the invention. TheDPF 22 is arranged downstream of theDOC 21. TheDOC 21 is used to detoxify toxic substances that are produced through combustion of air-fuel mixture in thecombustion chambers 10 a. TheDPF 22 is used to trap particulate matter contained in exhaust gas. A catalytic converter, other than theDOC 21 or theDPF 22, may be further incorporated in the exhaustgas control apparatus 19. - When an embodiment of the invention is applied to a spark-ignition internal combustion engine, a compact three-way catalyst is typically used as the first exhaust gas treatment unit of the invention instead of the
DOC 21. - There is a first exhaust gas burble zone Z1 in the
exhaust passage 18 a just on the upstream side of theDOC 21. The first exhaust gas burble zone Z1 is a zone in which exhaust gas flowing along a part of awall face 18 e, which defines theexhaust passage 18 a, burbles away from the part of thewall face 18 e and, as a result, exhaust gas disproportionately flows into an upstream end face 21 a of theDOC 21. Usually, the first exhaust gas burble zone Z1 is located at the upstream end side of acone portion 18 b in which the passage sectional area of theexhaust pipe 18 steeply increases, and the sectional shape of the part of thewall face 18 e of theexhaust passage 18 a in the first exhaust gas burble zone Z1, taken along the flow direction of exhaust gas, includes a convex curved line shown inFIG. 3 . - A
first plasma actuator 23 is arranged at the part of thewall face 18 e of theexhaust passage 18 a in the first exhaust gas burble zone Z1. Thefirst plasma actuator 23 is used to generate air current toward theDOC 21 along the part of thewall face 18 e. The principle, basic configuration, and the like, of thefirst plasma actuator 23 are known in Japanese Patent Application Publication No. 2012-180799 (JP 2012-180799 A), or the like, and will be simply described below. Thefirst plasma actuator 23 in the present embodiment is formed of a group offirst electrodes 23 a, a group ofsecond electrodes 23 b, adielectric layer 23 c and aninsulation layer 23 d as main components. Thefirst plasma actuator 23 further includes aninverter 24, afirst switch 25, and the like. The group offirst electrodes 23 a are arranged at set intervals on one surface of the thin-film dielectric layer 23 c, facing toward theexhaust passage 18 a. The group ofsecond electrodes 23 b are arranged at the set intervals same as the group offirst electrodes 23 a on the other surface of thedielectric layer 23 c, facing toward thewall face 18 e that defines theexhaust passage 18 a. Theinsulation layer 23 d coats the group ofsecond electrodes 23 b, and is bonded to thewall face 18 e that defines theexhaust passage 18 a. In the present embodiment, in order to prevent degradation and corrosion of the group offirst electrodes 23 a due to exhaust gas flowing through theexhaust passage 18 a, the group offirst electrodes 23 a are coated with a thin-filminsulation protection layer 23 e. The group ofsecond electrodes 23 b are arranged slightly offset to the downstream side in relative position with respect to the group offirst electrodes 23 a along an arrangement direction in which the groups of first andsecond electrodes exhaust passage 18 a. The group ofsecond electrodes 23 b are connected to theinverter 24 via thefirst switch 25. The on/off operation of thefirst switch 25, that is, the on/off state of energization to thefirst plasma actuator 23, is controlled by theECU 17. - It should be noted that, because the thickness of the
first plasma actuator 23 is extremely thin and is about several micrometers to several hundreds of micrometers, thefirst plasma actuator 23 installed on thewall face 18 e that defines theexhaust passage 18 a does not substantially interfere with flow of exhaust gas. Thefirst plasma actuator 23 does not need to be arranged over the entire circumference of theexhaust passage 18 a in the first exhaust gas burble zone Z1. Thefirst plasma actuator 23 may be arranged only at a portion having a particularly large curvature in the first exhaust gas burble zone Z1. In an embodiment of the invention, because thefirst plasma actuator 23 is arranged in the high-temperature exhaust passage 18 a, the groups ofelectrodes dielectric layer 23 c, theinsulation layer 23 d, theinsulation protection layer 23 e, and the like, are desirably made of materials having high heat resistance. As such materials, for example, the electrodes may be made of iron or nickel and thedielectric layer 23 c, theinsulation layer 23 d and theinsulation protection layer 23 e may be made of ceramics, or the like. - An input energy
amount setting unit 17 b of theECU 17 stores a map shown inFIG. 5 . The relationship between a flow rate Q of exhaust gas flowing through theexhaust passage 18 a per unit time and a voltage V1 that is applied to thefirst plasma actuator 23 is set in advance in the map. Basically, the operation of thefirst plasma actuator 23 is controlled via thefirst switch 25 such that the amount of energy that is input to thefirst plasma actuator 23 increases as the exhaust gas flow rate Q increases. In the present embodiment, the input energyamount setting unit 17 b sets the voltage V1 that is applied to thefirst plasma actuator 23, as the amount of energy that is input to thefirst plasma actuator 23, on the basis of information from the above-describedair flow meter 16. Theinverter 24 is supplied with electric power from an in-vehiclesecondary battery 26. Theinverter 24 is able to change the output voltage, for example, within the range of about 1 to 10 kV. Theinverter 24 applies the voltage V1, set by the input energyamount setting unit 17 b, to thefirst plasma actuator 23 at a predetermined driving frequency via thefirst switch 25, of which the on/off state is controlled by theECU 17. - As a mode of controlling the amount of energy that is input to the
first plasma actuator 23, the amount of input energy is controlled by changing the voltage V that is applied to thefirst plasma actuator 23 in the present embodiment. However, it is also possible to control the amount of input energy by changing the driving frequency of thefirst plasma actuator 23, for example, within the range of about 1 to 10 kHz. Alternatively, the amount of input energy may be controlled by changing both the applied voltage V1 and the driving frequency or a similar advantageous effect may be obtained by applying direct-current pulse voltage to thefirst plasma actuator 23. - When the high-frequency high voltage V1 is applied between the group of
first electrodes 23 a and the group ofsecond electrodes 23 b in this way, plasma is generated in a surface zone of theinsulation protection layer 23 e just downstream of each individualfirst electrode 23 a, and air current indicated by the arrows inFIG. 4 is generated accordingly. Exhaust gas intervening therearound is dragged by such generated air current and is prevented from burbling away from thewall face 18 e that defines theexhaust passage 18 a, with the result that the exhaust gas flows into the upstream end face 21 a of theDOC 21 in a diffused state. In this case, the strength of air current that is generated as a result of generation of plasma is directly proportional to the amount of energy that is input to the groups of first andsecond electrodes - When the
DPF 22 is arranged downstream of theDOC 21 as in the case of the present embodiment, soot contained in exhaust gas is oxidized by the operation of thefirst plasma actuator 23, so it is possible to further reduce the amount of soot contained in exhaust gas flowing into theDPF 22 through theDOC 21. As a result, it is possible to reduce the frequency of the process of regenerating theDPF 22. - A
catalyst temperature sensor 27 is attached to theDOC 21 as a temperature acquisition device configured to acquire the temperature of a catalytic converter according to an embodiment of the invention. Information about the temperature of theDOC 21, acquired by thecatalyst temperature sensor 27, is output to theECU 17. TheECU 17 applies the high voltage V1 to thefirst plasma actuator 23 by switching thefirst switch 25 to an energized state only when the temperature TC of theDOC 21 is higher than or equal to an activation lower limit temperature TCL of theDOC 21 and the temperature TC of theDOC 21 is lower than or equal to an upper limit temperature TCH of theDOC 21. - The temperature TC of the
DOC 21, acquired by thecatalyst temperature sensor 27, is desirably the temperature of a zone different from a zone into which exhaust gas flows because of the first exhaust gas burble zone Z1, that is, a zone into which exhaust gas is difficult to flow. In the present embodiment, the temperature of an outer peripheral end of theDOC 21 at a portion downstream of aheat insulation partition 21 b (described later) is acquired. Instead of thecatalyst temperature sensor 27, an exhaust gas temperature sensor for detecting an exhaust gas temperature may be arranged at at least one of a portion upstream of the exhaustgas control apparatus 19 and a portion downstream of the exhaustgas control apparatus 19, and the temperature TC of theDOC 21 may be estimated on the basis of detected information from the exhaust gas temperature sensor. Alternatively, a temporal change in the temperature TC of theDOC 21 from the start of a warm-up may be obtained in advance by an experiment, and the temperature TC of theDOC 21 may be estimated on the basis of a time from the start of the warm-up. - The cylindrical
heat insulation partition 21 b made of a heat-resistant material having a lower thermal conductivity than air, such as Porextherm WDS (trademark) produced by Kurosaki Harima Corporation, is provided at the upstream end of theDOC 21 in theDOC 21 in the present embodiment. Instead of using such a special material, theheat insulation partition 21 b may be an air layer. In this case, a cylindrical air gap just needs to be provided in theDOC 21. The zone surrounded by the cylindricalheat insulation partition 21 b is a zone in which exhaust gas disproportionately flows into theDOC 21 as a result of burble of exhaust gas in the first exhaust gas burble zone Z1 in a state where thefirst plasma actuator 23 is not operated. Usually, the passage sectional area of theheat insulation partition 21 b is substantially equal to or slightly larger than the passage sectional area of theexhaust pipe 18 that is connected to thecone portion 18 b in the first exhaust gas burble zone Z1, and the outline shape of theheat insulation partition 21 b is similar to the sectional shape of theexhaust pipe 18. Thus, in a state where thefirst plasma actuator 23 is not operated, it is possible to guide the major portion of exhaust gas to the zone of theDOC 21, surrounded by theheat insulation partition 21 b. Thus, it is possible to quickly raise the temperature of only the zone of theDOC 21, surrounded by theheat insulation partition 21 b, during a warm-up of theengine 10. The length of theheat insulation partition 21 b along the longitudinal direction of the DOC 21 (the flow direction of exhaust gas) is desirably smaller than or equal to a half of theDOC 21 and may be about one-third or one quarter of theDOC 21. -
FIG. 6 schematically shows the temperature rise characteristic of theDOC 21 according to the present embodiment during a warm-up of theengine 10. The continuous line inFIG. 6 indicates a temperature change at the center portion of the upstream end face 21 a of theDOC 21, surrounded by theheat insulation partition 21 b, in a state where thefirst plasma actuator 23 is not operated. The dashed line inFIG. 6 indicates a temperature change at the center portion of the upstream end of theDOC 21 in the case where theheat insulation partition 21 b is not provided in a state where thefirst plasma actuator 23 is not operated. The alternate long and two-short dashes line inFIG. 6 indicates a temperature change at the center portion of the upstream end face 21 a in the case where exhaust gas flows into theDOC 21 in the case where theheat insulation partition 21 b is not provided in a state where exhaust gas is diffused by operating thefirst plasma actuator 23. The dotted line inFIG. 6 indicates a temperature change of a zone of which the temperature is detected by thecatalyst temperature sensor 27 in the present embodiment. - According to the graph, when the
heat insulation partition 21 b is provided in theDOC 21, the temperature of the center portion of theDOC 21 reaches the catalyst activation lower limit temperature TCL at time t1. It is understood that the center portion of theDOC 21 is heated to the catalyst activation lower limit temperature TLC in a period of time shorter than or equal to half of a time that is taken in the case indicated by the dashed line where theheat insulation partition 21 b is not provided and the corresponding time is t2. Therefore, by providing theheat insulation partition 21 b and stopping the operation of thefirst plasma actuator 23 during a warm-up, it is possible to improve purification of exhaust gas during a warm-up of theengine 10 by further quickly activating only the center portion of theDOC 21. It appears that the temperature TC that is detected by thecatalyst temperature sensor 27, that is, the temperature of the outer peripheral end of theDOC 21, steeply rises after time t3 at which the temperature of the outer peripheral end of theDOC 21 reaches the catalyst activation lower limit temperature TCL from time t0 at which theengine 10 is started. The reason is that thefirst plasma actuator 23 begins to operate at time t3 at which the temperature of the outer peripheral end of theDOC 21 has reached the catalyst activation lower limit temperature TCL and exhaust gas flows into theDOC 21 in a diffused state. That is, by operating thefirst plasma actuator 23 at time t3 at which the acquired temperature TC of theDOC 21 has reached the catalyst activation lower limit temperature TCL, it is possible to further early effectively cause thewhole DOC 21 to function. - It should be noted that the position of the
heat insulation partition 21 b with respect to theDOC 21 may significantly deviate from the center portion of theDOC 21, which is described in the case of the present embodiment, because of the shape of thecone portion 18 b, an angle at which theexhaust pipe 18 is connected to thecone portion 18 b, and the like. When theheat insulation partition 21 b is not provided in the catalytic converter, the temperature TC of theDOC 21, which is acquired by the above-describedcatalyst temperature sensor 27, is desirably the temperature of the zone at the outer peripheral end of the upstream end face 21 a of theDOC 21.FIG. 7 shows the sectional structure of such a first exhaust gas treatment unit according to another embodiment. In the present embodiment, because theheat insulation partition 21 b is not provided in theDOC 21, thecatalyst temperature sensor 27 is attached to the outer peripheral end of the upstream end face 21 a of theDOC 21 at a portion farthest from theexhaust pipe 18 that is connected to thecone portion 18 b. Thefirst plasma actuator 23 is installed in the first exhaust gas burble zone Z1 having a convex curved face of a zone in which theexhaust pipe 18 is connected to thecone portion 18 b. When theheat insulation partition 21 b is provided in theDOC 21, theheat insulation partition 21 b may be provided at a portion indicated by the alternate long and two-short dashes line inFIG. 7 , and may be provided as an air gap as described above. - The procedure of operating the above-described
first plasma actuator 23 will be described with reference to the flowchart ofFIG. 8 . Initially, in step S11, it is determined whether the catalyst temperature TC is higher than or equal to the catalyst activation lower limit temperature TCL. When it is determined that the catalyst temperature TC is higher than or equal to the catalyst activation lower limit temperature TCL, that is, when it is determined that the catalyst temperature TC is a temperature at which there is a possibility that thefirst plasma actuator 23 is allowed to be operated, the process proceeds to step S12. In step S12, it is determined whether the catalyst temperature TC is lower than or equal to the upper limit temperature TCH. When it is determined that the catalyst temperature TC is lower than or equal to the upper limit temperature TCH, that is, when it is desirable to diffuse exhaust gas over the entire area of theDOC 21 by operating thefirst plasma actuator 23, the process proceeds to step S13. In step S13, the exhaust gas flow rate Q is acquired. Subsequently, in step S14, the applied voltage V1 corresponding to the acquired exhaust gas flow rate Q is set. Then, in step S15, thefirst plasma actuator 23 is driven at the set applied voltage V1. - Thus, air current commensurate with the exhaust gas flow rate Q is generated toward the first exhaust gas treatment unit along the part of the
wall face 18 e of theexhaust passage 18 a in the first exhaust gas burble zone Z1. As a result, exhaust gas flowing along the part of thewall face 18 e of theexhaust passage 18 a in the first exhaust gas burble zone Z1 is dragged by the air current, flows without burbling away from the part of thewall face 18 e of theexhaust passage 18 a, and then flows over the entire area of theDOC 21 in a diffused state. Thus, it is possible to effectively utilize theDOC 21 at a maximum. - After that, it is determined in step S16 whether a first flag is set. However, because the first flag is not set at first, the process proceeds to step S17. In step S17, the first flag is set, and then the process returns to step S11 again.
- On the other hand, when it is determined in step S11 that the catalyst temperature TC is lower than the catalyst activation lower limit temperature TCL, that is, when it is desirable to quickly raise the temperature of the zone of the
DOC 21, surrounded by theheat insulation partition 21 b, the process proceeds to step S18. As in the case where it is determined in step S12 that the catalyst temperature TC is higher than the upper limit temperature TCH, the process proceeds to step S18. In step S18, it is determined whether the first flag is set. When it is determined that the first flag is set, the operation of thefirst plasma actuator 23 is stopped by setting the applied voltage V1 to zero in step S19, the first flag is reset in step S20, and then the process returns to step S11 again. Thus, it is possible to avoid supplying unnecessary electric power to thefirst plasma actuator 23. - When it is determined in step S11 that the catalyst temperature TC is lower than the catalyst activation lower limit temperature TCL, the operation of the
first plasma actuator 23 is stopped. Thus, exhaust gas disproportionately flows from the first exhaust gas burble zone Z1 into the zone surrounded by theheat insulation partition 21 b of theDOC 21. As a result, it is possible to further quickly raise the temperature of the zone surrounded by theheat insulation partition 21 b of theDOC 21 to the activation lower limit temperature TCL or higher, so it is possible to facilitate purification of exhaust gas during a warm-up of theengine 10. - A swelled
portion 28 is provided in theexhaust pipe 18 downstream of the exhaustgas control apparatus 19. The swelledportion 28 has an increased passage sectional area. Apartition wall 29 is arranged in theexhaust passage 18 a. Thepartition wall 29 extends along the flow direction of exhaust gas so as to partition off a space in the swelledportion 28. Aninlet portion 28 a is provided between the upstream end of thepartition wall 29 and thewall face 18 e that defines the swelledportion 28 of theexhaust pipe 18. Anoutlet portion 28 b is provided between the downstream end of thepartition wall 29 and thewall face 18 e that defines the swelledportion 28 of theexhaust pipe 18. Theinlet portion 28 a is used to cause exhaust gas to flow into the swelledportion 28 side. Theoutlet portion 28 b is used to cause exhaust gas in the swelledportion 28 to flow out. Thus, theexhaust passage 18 a downstream of the exhaustgas control apparatus 19 is branched into amain exhaust passage 18 c and anauxiliary exhaust passage 18 d. Themain exhaust passage 18 c is not bypassed to the swelledportion 28. Theauxiliary exhaust passage 18 d is bypassed to the swelledportion 28. The exhaustheat recovery device 20 communicates with awater jacket 30 a provided in acylinder block 30. The exhaustheat recovery device 20 is arranged in theauxiliary exhaust passage 18 d, and exchanges heat between exhaust gas flowing through theauxiliary exhaust passage 18 d and coolant of theengine 10. The exhaustheat recovery device 20 serves as a second exhaust gas treatment unit of the invention. The exhaustheat recovery device 20 is used to achieve an early warm-up of theengine 10 by raising the temperature of coolant by the use of heat of exhaust gas. For this purpose, the above-describedDPF 22 may be arranged in theexhaust passage 18 a at a portion downstream of the exhaustheat recovery device 20. In this case, it is possible to further efficiently recover exhaust heat. - In the case of the embodiment shown in
FIG. 3 , there is a second exhaust gas burble zone Z2 in which exhaust gas flowing along a part of thewall face 18 e, which defines an upstream branching zone of the swelledportion 28, burbles away from the part of thewall face 18 e and, as a result, the amount of exhaust gas flowing into the swelledportion 28 is reduced. Asecond plasma actuator 31 is arranged at the part of thewall face 18 e of theexhaust passage 18 a in the second exhaust gas burble zone Z2. The sectional shape of the second exhaust gas burble zone Z2, taken along the flow direction of exhaust gas, includes a convex curved line. Thesecond plasma actuator 31 is used to generate air current toward the exhaustheat recovery device 20 along the part of thewall face 18 e. Thesecond plasma actuator 31 basically has the same configuration as the above-describedfirst plasma actuator 23, and is connected to theinverter 24 via asecond switch 32. The on/off state of thesecond switch 32 is controlled by theECU 17. However, an applied voltage V2, a driving frequency, and the like, to thesecond plasma actuator 31 by theinverter 24 are constant values set in advance in response to the curvature of the second exhaust gas burble zone Z2. - A clearance W1 from a part of a
wall face 28 c of the swelledportion 28, which defines theauxiliary exhaust passage 18 d, to thepartition wall 29 along a direction perpendicular to thepartition wall 29 is set so as to be shorter than a clearance W2 from thesame wall face 28 c to a part of the wall face 28 e, which defines theexhaust passage 18 a just before branching along the direction perpendicular to thepartition wall 29. In other words, a distance from the center of themain exhaust passage 18 c to thewall face 18 e that defines theexhaust passage 18 a just before branching is set so as to be shorter than a distance from the center of themain exhaust passage 18 c to thepartition wall 29. Thus, it is possible to suppress an unnecessary rise in the temperature of coolant by making part of exhaust gas difficult to flow into the exhaustheat recovery device 20 side after completion of a warm-up of theengine 10. In order to reliably suppress an unnecessary rise in the temperature of coolant after completion of a warm-up, a mechanical shutter mechanism for opening or closing theoutlet portion 28 b may be incorporated. However, it should be noted that component cost, maintenance, and the like, are required for incorporating a mechanical shutter mechanism. In the present embodiment, because there is no movable portion for opening or closing theinlet portion 28 a or theoutlet portion 28 b, reliability is high, and it is possible to reduce component cost and pressure loss. - A
coolant temperature sensor 33 is arranged in thecylinder block 30. Thecoolant temperature sensor 33 acquires the temperature TW of coolant of theengine 10 and outputs the detected information to theECU 17. The coolant of theengine 10 flows through thewater jacket 30 a. TheECU 17 operates thesecond plasma actuator 31 by switching thesecond switch 32 to the energized state only when the acquired temperature TW of coolant is lower than a temperature TWL set in advance. - The procedure of operating the
second plasma actuator 31 will be described with reference to the flowchart shown inFIG. 9 . Initially, in step S21, it is determined whether the coolant temperature TW is lower than the lower limit coolant temperature TWL. When the coolant temperature TW is lower than the lower limit coolant temperature TWL, that is, when it is determined that a warm-up of theengine 10 is required, thesecond plasma actuator 31 is driven in step S22. Thus, it is possible to efficiently guide part of exhaust gas, which has passed through the exhaustgas control apparatus 19, to theauxiliary exhaust passage 18 d via theinlet portion 28 a. Exhaust gas guided to theauxiliary exhaust passage 18 d exchanges heat with coolant while passing through the exhaustheat recovery device 20, raises the temperature of coolant, flows out from theauxiliary exhaust passage 18 d via theoutlet portion 28 b, merges into exhaust gas flowing through themain exhaust passage 18 c, and then flows down to the muffler side. Subsequently, in step S23, it is determined whether a second flag is set. Because the second flag is not set at first, the process proceeds to step S24. In step S24, the second flag is set, and then the process returns to step S21 again. - In this way, electric power is supplied to the
second plasma actuator 31 until the coolant temperature TW becomes higher than or equal to the lower limit coolant temperature TWL, and the coolant temperature is raised by guiding part of exhaust gas to the exhaustheat recovery device 20. Thus, a warm-up is facilitated. - When it is determined in step S21 that the coolant temperature TW is higher than or equal to the lower limit coolant temperature TWL, that is, when a warm-up of the
engine 10 has completed, the process proceeds to step S25. In step S25, it is determined whether the second flag is set. When it is determined that the second flag is set, that is, when electric power is being supplied to thesecond plasma actuator 31, the process proceeds to step S26. The operation of thesecond plasma actuator 31 is stopped by setting the voltage V2, applied to thesecond plasma actuator 31, to zero in step S26. After that, the process proceeds to step S27, the second flag is reset, and the process returns to step S21 again. - In this state, part of exhaust gas is difficult to flow into the
auxiliary exhaust passage 18 d via theinlet portion 28 a because of a step between thepartition wall 29 and thewall face 18 e that defines theexhaust passage 18 a just before branching, so it is possible to suppress an unnecessary rise in the coolant temperature. It is also possible to prevent supply of unnecessary electric power to thesecond plasma actuator 31 after completion of a warm-up of theengine 10. - The invention should be interpreted from only matters described in the appended claims, and any modifications and changes of the above-described embodiment, included in the concept of the invention are possible other than the described matters. That is, all the matters in the above-described embodiment are not intended to limit the invention, but they can be arbitrarily modified in response to an application, a purpose, and the like, including a configuration that is not directly relevant to the invention.
Claims (20)
1. An exhaust gas treatment apparatus for an internal combustion engine, the exhaust gas treatment apparatus comprising:
an exhaust gas treatment unit arranged in an exhaust passage of the internal combustion engine, the exhaust passage being configured such that i) exhaust gas flowing along a part of a wall face, which defines the exhaust passage, burbles away from the part of the wall face in an exhaust gas burble zone and ii) as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone, exhaust gas disproportionately flows into the exhaust gas treatment unit or an amount of exhaust gas flowing into the exhaust gas treatment unit reduces; and
a plasma actuator arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, the plasma actuator being configured to generate air current in exhaust gas toward the exhaust gas treatment unit along the part of the wall face inside the exhaust passage.
2. The exhaust gas treatment apparatus according to claim 1 , wherein
a sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone, taken along a flow direction of exhaust gas, includes a convex curved line.
3. The exhaust gas treatment apparatus according to claim 1 , further comprising:
a flow rate acquisition device configured to acquire a flow rate of exhaust gas flowing through the exhaust passage; and
a controller configured to control an amount of energy that is input to the plasma actuator, wherein
the exhaust gas treatment unit includes a catalytic converter configured to purify exhaust gas, and
the controller is configured to control the plasma actuator such that the amount of energy that is input to the plasma actuator increases as the acquired flow rate of exhaust gas increases.
4. The exhaust gas treatment apparatus according to claim 3 , further comprising:
a temperature acquisition device configured to acquire a temperature of the catalytic converter, wherein
the controller is configured to, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, input energy to the plasma actuator.
5. The exhaust gas treatment apparatus according to claim 1 , wherein
the exhaust gas treatment unit includes a catalytic converter configured to purify exhaust gas,
the exhaust gas treatment apparatus further comprises:
a temperature acquisition device configured to acquire a temperature of the catalytic converter; and
a controller configured to control an amount of energy that is input to the plasma actuator, and
the controller is configured to, when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, input energy to the plasma actuator.
6. The exhaust gas treatment apparatus according to claim 4 , wherein
the controller is configured to, when the acquired temperature of the catalytic converter is lower than or equal to an upper limit temperature of the catalytic converter, input energy to the plasma actuator.
7. The exhaust gas treatment apparatus according to claim 3 , wherein
the catalytic converter includes a cylindrical heat insulation partition surrounding a zone of part of the catalytic converter along a flow direction of exhaust gas, and
the zone surrounded by the heat insulation partition includes a zone into which exhaust gas disproportionately flows as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone.
8. The exhaust gas treatment apparatus according to claim 7 , wherein
a length of the heat insulation partition along the flow direction of exhaust gas is shorter than a length of the catalytic converter along the flow direction of exhaust gas, and
an upstream end of the heat insulation partition along the flow direction of exhaust gas is located at an upstream end of the catalytic converter along the flow direction of exhaust gas.
9. The exhaust gas treatment apparatus according to claim 7 , wherein
the heat insulation partition is an air layer.
10. The exhaust gas treatment apparatus according to claim 4 , wherein
the acquired temperature of the catalytic converter is a temperature of a zone different from a zone into which exhaust gas disproportionately flows because of the exhaust gas burble zone.
11. The exhaust gas treatment apparatus according to claim 3 , further comprising:
a particulate filter configured to trap particulate matter contained in exhaust gas, wherein
the particulate filter is arranged downstream of the catalytic converter.
12. The exhaust gas treatment apparatus according to claim 1 , wherein
the exhaust passage is branched into two by a partition wall extending along a flow direction of exhaust gas,
the exhaust gas treatment unit includes an exhaust heat recovery device arranged in one of the branched exhaust passages and configured to exchange heat between exhaust gas flowing through said one of the branched exhaust passages and coolant of the internal combustion engine,
the exhaust gas burble zone is located at a portion at which the exhaust passage is branched, and
the exhaust passage is configured such that the amount of exhaust gas flowing into said one of the branched exhaust passages reduces as a result of burble of exhaust gas away from a part of a wall face of the exhaust passage in the exhaust gas burble zone.
13. The exhaust gas treatment apparatus according to claim 12 , further comprising:
a coolant temperature sensor configured to acquire a temperature of coolant of the internal combustion engine; and
a controller configured to, when the acquired temperature of coolant is lower than a temperature set in advance, input energy to the plasma actuator.
14. An exhaust gas treatment method for an internal combustion engine,
an exhaust passage of the internal combustion engine being configured such that exhaust gas flowing along a part of a wall face, which defines the exhaust passage at a portion upstream of a catalytic converter for purifying exhaust gas from the internal combustion engine, disproportionately flows into an exhaust gas treatment unit arranged in the exhaust passage as a result of burble of exhaust gas away from the part of the wall face in an exhaust gas burble zone,
a plasma actuator being arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, the plasma actuator being configured to generate air current along the wall face of the exhaust passage in exhaust gas inside the exhaust passage,
the exhaust gas treatment method comprising:
acquiring a temperature of the catalytic converter; and
when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, inputting energy to the plasma actuator.
15. An exhaust gas treatment method for an internal combustion engine,
an exhaust passage of the internal combustion engine being configured such that exhaust gas flowing along a part of a wall face, which defines the exhaust passage at a portion upstream of a catalytic converter for purifying exhaust gas from the internal combustion engine, disproportionately flows into the catalytic converter as a result of burble of exhaust gas away from the part of the wall face in an exhaust gas burble zone,
a plasma actuator being arranged at the part of the wall face of the exhaust passage in the exhaust gas burble zone, the plasma actuator being configured to generate air current along the wall face of the exhaust passage in exhaust gas inside the exhaust passage,
the exhaust gas treatment method comprising:
acquiring an exhaust gas flow rate; and
causing exhaust gas to flow into the catalytic converter in a diffused state by applying larger energy to the plasma actuator as the acquired exhaust gas flow rate increases.
16. The exhaust gas treatment method according to claim 14 , further comprising:
acquiring a temperature of the catalytic converter; and
when the acquired temperature of the catalytic converter is higher than or equal to an activation lower limit temperature of the catalytic converter, causing exhaust gas to flow into the catalytic converter in a diffused state.
17. The exhaust gas treatment method according to any one of claim 14 , wherein
a sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone, taken along a flow direction of exhaust gas, includes a convex curved line.
18. The exhaust gas treatment method according to claim 14 , wherein
a cylindrical heat insulation partition surrounding a zone of part of the catalytic converter along a flow direction of exhaust gas is provided in the catalytic converter such that the zone surrounded by the heat insulation partition includes a zone into which exhaust gas disproportionately flows as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone and, when the acquired temperature of the catalytic converter is lower than an activation lower limit temperature of the catalytic converter, a major portion of exhaust gas is guided to the zone of the catalytic converter, surrounded by the heat insulation partition.
19. The exhaust gas treatment method according to claim 15 , wherein
a sectional shape of the part of the wall face of the exhaust passage in the exhaust gas burble zone, taken along a flow direction of exhaust gas, includes a convex curved line.
20. The exhaust gas treatment method according to claim 15 , wherein
a cylindrical heat insulation partition surrounding a zone of part of the catalytic converter along a flow direction of exhaust gas is provided in the catalytic converter such that the zone surrounded by the heat insulation partition includes a zone into which exhaust gas disproportionately flows as a result of burble of exhaust gas away from the part of the wall face of the exhaust passage in the exhaust gas burble zone and, when the acquired temperature of the catalytic converter is lower than an activation lower limit temperature of the catalytic converter, a major portion of exhaust gas is guided to the zone of the catalytic converter, surrounded by the heat insulation partition.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2015054855A JP2016176341A (en) | 2015-03-18 | 2015-03-18 | Exhaust treatment device for internal combustion engine |
JP2015-054855 | 2015-03-18 |
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US20160273433A1 true US20160273433A1 (en) | 2016-09-22 |
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US15/072,573 Abandoned US20160273433A1 (en) | 2015-03-18 | 2016-03-17 | Exhaust gas treatment apparatus and exhaust gas treatment method for internal combustion engine |
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US (1) | US20160273433A1 (en) |
EP (1) | EP3070283B1 (en) |
JP (1) | JP2016176341A (en) |
KR (1) | KR101762535B1 (en) |
CN (1) | CN105986872A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US20200150699A1 (en) * | 2018-11-09 | 2020-05-14 | Hamilton Sundstrand Corporation | Method for managing over-temperature excursions in a failed-fixed control system |
US11181024B2 (en) * | 2018-10-25 | 2021-11-23 | Volkswagen Aktiengesellschaft | Method for operating an internal combustion engine as well as internal combustion engine |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP6926892B2 (en) * | 2017-09-25 | 2021-08-25 | 株式会社Ihi | Plasma actuator |
CN110159407B (en) * | 2019-05-24 | 2021-03-30 | 南通迈程汽车技术有限公司 | Processing device for abnormal emission of automobile exhaust |
CN110160795B (en) * | 2019-05-27 | 2021-01-26 | 武汉东测科技有限责任公司 | Tail gas treatment system of gasoline engine pedestal and test method thereof |
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US20120036850A1 (en) * | 2010-08-09 | 2012-02-16 | Cummins Intellectual Properties, Inc. | Waste heat recovery system for recapturing energy after engine aftertreatment systems |
US20140056780A1 (en) * | 2012-08-24 | 2014-02-27 | Robin Crawford | Catalytic converter component and process for its manufacture |
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JP5700974B2 (en) * | 2010-08-06 | 2015-04-15 | ダイハツ工業株式会社 | Plasma actuator |
JP2012102693A (en) | 2010-11-12 | 2012-05-31 | Mitsui Eng & Shipbuild Co Ltd | Device and method for decomposing gas |
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JP5704110B2 (en) * | 2012-04-18 | 2015-04-22 | トヨタ自動車株式会社 | Exhaust gas purification device for internal combustion engine and addition valve holder |
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- 2015-03-18 JP JP2015054855A patent/JP2016176341A/en active Pending
-
2016
- 2016-03-09 EP EP16159450.2A patent/EP3070283B1/en not_active Not-in-force
- 2016-03-15 KR KR1020160030892A patent/KR101762535B1/en active IP Right Grant
- 2016-03-16 CN CN201610148402.5A patent/CN105986872A/en active Pending
- 2016-03-17 US US15/072,573 patent/US20160273433A1/en not_active Abandoned
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US20050063879A1 (en) * | 2003-09-24 | 2005-03-24 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification system |
US20120036850A1 (en) * | 2010-08-09 | 2012-02-16 | Cummins Intellectual Properties, Inc. | Waste heat recovery system for recapturing energy after engine aftertreatment systems |
US20140056780A1 (en) * | 2012-08-24 | 2014-02-27 | Robin Crawford | Catalytic converter component and process for its manufacture |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US11181024B2 (en) * | 2018-10-25 | 2021-11-23 | Volkswagen Aktiengesellschaft | Method for operating an internal combustion engine as well as internal combustion engine |
US20200150699A1 (en) * | 2018-11-09 | 2020-05-14 | Hamilton Sundstrand Corporation | Method for managing over-temperature excursions in a failed-fixed control system |
US10908624B2 (en) * | 2018-11-09 | 2021-02-02 | Hamilton Sunstrand Corporation | Method for managing over-temperature excursions in a failed-fixed control system |
Also Published As
Publication number | Publication date |
---|---|
EP3070283B1 (en) | 2017-07-12 |
KR101762535B1 (en) | 2017-07-27 |
EP3070283A1 (en) | 2016-09-21 |
KR20160112985A (en) | 2016-09-28 |
CN105986872A (en) | 2016-10-05 |
JP2016176341A (en) | 2016-10-06 |
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