WO2015029612A1 - Exhaust purification system for an internal combustion engine - Google Patents
Exhaust purification system for an internal combustion engine Download PDFInfo
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- WO2015029612A1 WO2015029612A1 PCT/JP2014/068374 JP2014068374W WO2015029612A1 WO 2015029612 A1 WO2015029612 A1 WO 2015029612A1 JP 2014068374 W JP2014068374 W JP 2014068374W WO 2015029612 A1 WO2015029612 A1 WO 2015029612A1
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- exhaust purification
- amount
- purification catalyst
- exhaust gas
- removal method
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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
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
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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
- F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
- F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
- F01N3/0842—Nitrogen oxides
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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
- F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
- F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
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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
- F01N2240/30—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 fuel reformer
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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
- F01N2430/00—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
- F01N2430/06—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics by varying fuel-air ratio, e.g. by enriching fuel-air mixture
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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
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- 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
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
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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
- 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
- F01N2900/08—Parameters used for exhaust control or diagnosing said parameters being related to the engine
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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
- 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
- F01N2900/1402—Exhaust gas composition
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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
- 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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- 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
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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
- F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
- F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
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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
- the present invention relates to an exhaust purification system of an internal combustion engine.
- the amount of reducing agent which is required for releasing the stored NO x from the exhaust purification catalyst and reduce it in the second NO x removal method that is, the amount of fuel which is required for making the air-fuel ratio of the exhaust gas rich, is larger compared with the amount of hydrocarbons, that is, the amount of reducing agent, which is required for
- the amount of reducing agent which is required for removing the NO x is greater in the case of using the second NO x removal method compared with the case of using the first NO x removal method. Therefore, it is preferable to use the first NO x removal method as much as possible.
- the first NO x removal method gives a high purification efficiency at the higher side of temperature of the exhaust purification catalyst compared with the second NO x removal method. Therefore, if the temperature of the exhaust purification catalyst rises, an N0 X removal method is switched from the second N0 X removal method to the first N0 X removal method. In this case, as explained above, it is preferable to use the first N0 X removal method as much as possible, so the temperature of the exhaust purification catalyst when an ⁇ removal method is switched from the second NO x removal method to the first NO x removal method is preferably as low as possible.
- the first N0 X removal method it is preferable to use the first N0 X removal method as much as possible, so the temperature of the exhaust purification catalyst when an ⁇ removal method is switched from the second NO x removal method to the first NO x removal method is preferably as low as possible.
- an NO x removal method is switched from the second NO x removal method to the first NO x removal method by using a different judgment criteria from the present invention.
- an exhaust purification system of an internal combustion engine comprising an exhaust purification catalyst arranged in an engine exhaust passage and a hydrocarbon feed valve arranged in the engine exhaust passage upstream of the exhaust purification catalyst, a precious metal catalyst being carried on an exhaust gas flow surface of the exhaust purification catalyst, a basic layer being formed around the precious metal catalyst, a first NO x removal method which reduces NO x contained in an exhaust gas by a reducing intermediate which is held on the basic layer and generated by
- ⁇ removal method switching means for switching an NO x removal method from the second NO x removal method to the first NO removal method when a temperature of the exhaust purification catalyst rises and exceeds a predetermined switching temperature, the NO x removal method switching means controls the switching temperature in accordance with an amount of NO x in the exhaust gas flowing into the exhaust purification
- FIG. 1 is an overall view of a
- FIG. 2 is a view which schematically shows the surface part of a catalyst carrier.
- FIG. 3 is a view for explaining an oxidation reaction at an exhaust purification catalyst.
- FIG. 4 is a view which shows changes in an air- fuel ratio of exhaust gas which flows into an exhaust purification catalyst.
- FIG. 5 is a view which shows an NO x purification rate Rl .
- FIGS. 6A and 6B are views for explaining an oxidation reduction reaction in an exhaust purification catalyst .
- FIGS. 7A and 7B are views for explaining an oxidation reduction reaction in an exhaust purification catalyst.
- FIG. 8 is a view which shows changes in an air- fuel ratio of exhaust gas which flows into an exhaust purification catalyst.
- FIG. 9 is a view which shows an NO x purification rate R2.
- FIGS. 10A and 10B are views which show a relationship between a vibration period ⁇ of hydrocarbon concentration and an NO x purification rate Rl, etc.
- FIGS. 11A, 11B and 11C are views which show maps of the injection amount of hydrocarbons, etc.
- FIG. 12 is a view which shows an NO x release control .
- FIG. 13 is a view which shows a map of an exhausted NO x amount NOXA.
- FIG. 14 is a view which shows a fuel injection timing.
- FIG. 15 is a view which shows a map of an additional hydrocarbon feed amount WR.
- FIG. 16 is a view which shows switching
- FIG. 17 is a view which shows another
- FIG. 18 is a view which shows a further
- FIGS. 19A and 19B are views which show a map of a base air-fuel ratio, etc.
- FIG. 20 is a view which shows a first NO x purification method and a second NO x purification method.
- FIG. 21 is a flow chart for performing an NO x purification control.
- FIG. 22 is a flow chart for performing another embodiment of an NO x purification control.
- FIG. 23 is a view which shows a change in an NO x amount etc. at the time of an accelerating operation of a vehicle.
- FIG. 24 is a time chart which shows a change in an amount of ⁇ flowing out from an exhaust purification catalyst, etc. at the time of an accelerating operation of a vehicle.
- FIGS. 25A, 25B and 25C are views which show an injection amount and an injection period of hydrocarbons from a hydrocarbon feed valve.
- FIGS. 26A and 26B are views for explaining an injection period of hydrocarbons from a hydrocarbon feed valve at the time of an accelerating operation of a vehicle .
- FIG. 27 is a flow chart for performing an NO x purification control, which shows another embodiment of a portion encircled by the dash and dotted line F in
- FIG. 28 is a flow chart for performing an NO x purification control, which shows a further embodiment of a portion encircled by the dash and dotted line F in
- FIG. 29 is a flow chart for performing an NO x purification control, which shows a still further
- FIG. 1 is an overall view of a compression ignition type internal combustion engine.
- 1 indicates an engine body, 2 a combustion chamber of each cylinder, 3 an electronically controlled fuel injector for injecting fuel into each combustion chamber 2, 4 an intake manifold, and 5 an exhaust manifold.
- the intake manifold 4 is connected through an intake duct 6 to an outlet of a compressor 7a of an exhaust turbocharger 7, while an inlet of the compressor 7a is connected through an intake air amount detector 8 to an air cleaner 9.
- a throttle valve 10 which is driven by an actuator is arranged.
- a cooling device 11 is arranged for cooling the intake air which flows through the inside of the intake duct 6.
- the engine cooling water is guided to the inside of the cooling device 11 where the engine cooling water is used to cool the intake air .
- the exhaust manifold 5 is connected to an inlet of an exhaust turbine 7b of the exhaust turbocharger 7, and an outlet of the exhaust turbine 7b is connected through an exhaust pipe 12 to an inlet of an exhaust purification catalyst 13.
- this exhaust is connected to an inlet of an exhaust turbine 7b of the exhaust turbocharger 7, and an outlet of the exhaust turbine 7b is connected through an exhaust pipe 12 to an inlet of an exhaust purification catalyst 13.
- purification catalyst 13 is comprised of an NO x storage catalyst 13. An outlet of the exhaust purification catalyst 13 is connected to a particulate filter 14 and, upstream of the exhaust purification catalyst 13 inside the exhaust pipe 12, a hydrocarbon feed valve 15 is arranged for feeding hydrocarbons comprised of diesel oil or other fuel used as fuel for a compression ignition type internal combustion engine.
- diesel oil is used as the hydrocarbons which are fed from the hydrocarbon feed valve 15.
- the present invention can also be applied to a spark ignition type internal combustion engine in which fuel is burned under a lean air-fuel ratio. In this case, from the hydrocarbon feed valve 15, hydrocarbons comprised of gasoline or other fuel used as fuel of a spark ignition type internal combustion engine are fed.
- EGR electronic controlled EGR control valve 17
- a cooling device 18 is arranged for cooling the EGR gas which flows through the inside of the EGR passage 16.
- the engine cooling water is guided to the inside of the cooling device 18 where the engine cooling water is used to cool the EGR gas.
- each fuel injector 3 is connected through a fuel feed tube 19 to a common rail 20. This common rail 20 is connected through an
- An electronic control unit 30 is comprised of a digital computer provided with a ROM (read only memory)
- a temperature sensor 23 is arranged for detecting the temperature of the exhaust gas flowing out from the exhaust purification catalyst 13, and a pressure difference sensor 24 for detecting a pressure difference before and after the particulate filter 14 is attached to the particulate filter 14.
- the output signals of these temperature sensor 23, pressure difference sensor 24 and intake air amount detector 8 are input through respectively corresponding AD converters 37 to the input port 35.
- an accelerator pedal 40 has a load sensor 41 connected to it which generates an output voltage proportional to the amount of depression L of the accelerator pedal 40.
- the output voltage of the load sensor 41 is input through a corresponding AD converter 37 to the input port 35.
- a crank angle sensor 42 is connected which generates an output pulse every time a crankshaft rotates by, for example, 15°.
- the output port 36 is connected through corresponding drive circuits 38 to each fuel injector 3, the actuator for driving the throttle valve 10, hydrocarbon feed valve 15, EGR control valve 17, and fuel pump 21.
- FIG. 2 schematically shows a surface part of a catalyst carrier which is carried on a substrate of the exhaust purification catalyst 13 shown in FIG. 1.
- a catalyst carrier 50 made of alumina on which precious metal catalysts 51 comprised of platinum Pt are carried.
- a basic layer 53 is formed which includes at least one element selected from potassium K, sodium Na, cesium Cs, or another such alkali metal, barium Ba, calcium Ca, or another such alkali earth metal, a
- the catalyst carrier 50 of the exhaust purification catalyst 13 in addition to platinum Pt, rhodium Rh or palladium Pd may be further carried.
- the exhaust gas flows along the top of the catalyst carrier 50, so the precious metal catalysts 51 can be said to be carried on the exhaust gas flow surfaces of the exhaust purification catalyst 13.
- the surface of the basic layer 53 exhibits basicity, so the surface of the basic layer 53 is called the "basic exhaust gas flow surface parts 54".
- FIG. 3 schematically shows the reformation action performed at the exhaust purification catalyst 13 at this time.
- the hydrocarbons HC which are injected from the hydrocarbon feed valve 15 become radical hydrocarbons HC with a small carbon number due to the precious metal catalyst 51.
- FIG. 4 shows the feed timing of hydrocarbons from the hydrocarbon feed valve 15 and the change in the air-fuel ratio (A/F) in of the exhaust gas which flows into the exhaust purification catalyst 13.
- the change in the air-fuel ratio (A/F) in depends on the change in concentration of the hydrocarbons in the exhaust gas which flows into the exhaust purification catalyst 13, so it can be said that the change in the air-fuel ratio (A/F) in shown in FIG. 4 expresses the change in concentration of the hydrocarbons.
- the air-fuel ratio (A/F) in becomes smaller, so, in FIG. 4, the more to the rich side the air-fuel ratio (A/F) in becomes, the higher the hydrocarbon concentration.
- FIG. 5 shows the NO x purification rate Rl by the exhaust purification catalyst 13 with respect to the catalyst temperatures TC of the exhaust purification catalyst 13 when periodically making the concentration of hydrocarbons which flow into the exhaust purification catalyst 13 change so as to, as shown in FIG. 4,
- FIGS. 6A and 6B schematically show the surface part of the
- FIGS. 6A and 6B show the reaction which is presumed to occur when the concentration of hydrocarbons which flow into the exhaust purification catalyst 13 is made to vibrate by within a predetermined range of amplitude and within a predetermined range of period.
- FIG. 6A shows when the concentration of
- FIG. 6B shows when hydrocarbons are fed from the hydrocarbon feed valve 15 and the air- fuel ratio (A/F) in of the exhaust gas flowing to the exhaust purification catalyst 13 is made rich, that is, the concentration of hydrocarbons which flow into the exhaust purification catalyst 13 becomes higher.
- the air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst 13 is maintained lean except for an instant, so the exhaust gas which flows into the exhaust purification catalyst 13 normally becomes a state of oxygen excess.
- part of the NO which is contained in the exhaust gas deposits on the exhaust purification catalyst 13, while part of the NO which is contained in the exhaust gas, as shown in FIG. 6A, is oxidized on the platinum 51 and becomes N0 2 .
- this N0 2 is further oxidized and becomes N0 3 .
- N0 2 ⁇ part of the N0 2 becomes N0 2 ⁇ . Therefore,, on the platinum Pt 51, N0 2 ⁇ and N0 3 are produced.
- the NO which is deposited on the exhaust purification catalyst 13 and the N0 2 ⁇ and N0 3 which are formed on the platinum Pt 51 are strong in activity. Therefore, below, these NO, N0 2 ⁇ , and N0 3 will be referred to as the "active NO x * ".
- the purification catalyst 13 is. made rich, the hydrocarbons successively deposit over the entire exhaust purification catalyst 13. The majority of the deposited hydrocarbons successively react with oxygen and are burned. Part of the deposited hydrocarbons are successively reformed and become radicalized inside of the exhaust purification catalyst 13 as shown in FIG. 3. Therefore, as shown in FIG. 6B, the hydrogen concentration around the active NO x * becomes higher. In this regard, if, after the active NO x * is produced, the state of a high oxygen concentration around the active NO x * continues for a constant time or more, the active NO x * is oxidized and is absorbed in the form of nitrate ions N0 3 ⁇ inside the basic layer 53.
- the first produced reducing intermediate is considered to be a nitro
- the basic exhaust gas flow surface parts 54 until the produced reducing intermediates R-NCO and R-NH 2 react with the NO x in the exhaust gas or the active NO x * or oxygen or break down themselves. For this reason, the basic exhaust gas flow surface parts 54 are provided.
- the precious metal catalysts 51 are carried on the exhaust gas flow surfaces of the exhaust purification catalyst 13. To hold the produced reducing intermediates R-NCO and R-NH 2 inside the exhaust
- the basic layers 53 are formed around the precious metal catalysts 51.
- the reducing intermediates R-NCO and R-NH 2 which are held on the basic layer 53 are converted to N 2 , C0 2 , and H 2 0.
- the vibration period of the hydrocarbon concentration is made the vibration period required for continuation of the
- injection interval is made 3 seconds.
- FIG. 7B shows the case where the air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst 13 is made rich when the ⁇ is absorbed in the form of nitrates inside of the basic layer 53.
- the oxygen concentration in the exhaust gas falls, so the reaction proceeds in the opposite direction ( ⁇ 3 ⁇ —»N0 2 ) , and consequently the nitrates absorbed in the basic layer 53 successively become nitrate ions N0 3 ⁇ and, as shown in FIG. IB, are released from the basic layer 53 in the form of N0 2 .
- the released N0 2 is reduced by the hydrocarbons HC and CO contained in the exhaust gas.
- FIG. 8 shows the case of making the air-fuel ratio (A/F)in of the exhaust gas which flows into the exhaust purification catalyst 13 temporarily rich
- the time interval of this rich control is 1 minute or more. In this case, the NO x which was absorbed in the basic layer 53 when the air-fuel ratio
- the basic layer 53 plays the role of an absorbent for temporarily absorbing NO x .
- the basic layer 53 temporarily adsorbs the NO x . Therefore, if using term of "storage” as a term including both "absorption” and "adsorption”, at this time, the basic layer 53 performs the role of an NO x storage agent for temporarily storing the N0 X .
- the exhaust purification catalyst 13 functions as an NO x storage catalyst which stores the NO x when the air-fuel ratio of the exhaust gas is lean and releases the stored N0 X when the oxygen concentration in the exhaust gas falls.
- the abscissa of the FIG. 9 shows the catalyst temperature TC of the exhaust purification catalyst 13.
- catalyst 13 function as an N0 X storage catalyst, as shown in FIG. 9, when the catalyst temperature TC is 250°C to 300°C, an extremely high N0 X purification rate is
- the N0 X purification rate R2 falls because if the catalyst temperature TC becomes 350°C or more, N0 X is less easily stored and the nitrates break down by heat and are released in the form of O2 from the exhaust purification catalyst 13. That is, so long as storing NO x in the form of nitrates, when the catalyst temperature TC is high, it is difficult to obtain a high ⁇ purification rate R2.
- the new NO x in the new NO x
- the amount of NO x stored in the form of nitrates is small, and consequently, as shown in FIG. 5, even when the catalyst temperature TC is high, a high NO x purification rate Rl is obtained.
- a hydrocarbon feed valve 15 for feeding hydrocarbons is arranged in the engine exhaust passage, an exhaust purification catalyst 13 is arranged in the engine exhaust passage downstream of the
- precious metal catalysts 51 are carried on the exhaust gas flow surfaces of the exhaust purification catalyst 13, the basic layers 53 are formed around the precious metal catalysts 51, the
- exhaust purification catalyst 13 has the property of reducing the N0 X contained in exhaust gas by the reducing intermediates which are held on the basic layers 53 if hydrocarbons are injected from the hydrocarbon feed valve 15 within a predetermined range of period and has the property of being increased in storage amount of NO x contained in exhaust gas if making the injection period of the hydrocarbon from the hydrocarbon feed valve 15 longer than this predetermined range, and, at the time of engine operation, the hydrocarbons are injected from the hydrocarbon feed valve 15 within the predetermined range of period to thereby reduce the NO x which is contained in the exhaust gas in the exhaust purification catalyst 13.
- the N0 x purification method which is shown from FIG. 4 to FIGS. 6A and 6B can be said to be a new N0 X purification method designed to remove N0 X without forming so much nitrates in the case of using an exhaust purification catalyst which carries precious metal
- this new NO x purification method when using this new NO x purification method, the nitrates which are detected from the basic layer 53 are smaller in amount compared with the case where making the exhaust purification catalyst 13 function as an NO x storage catalyst. Note that, this new NO x purification method will be referred to below as the "first NO x removal method".
- the injection period ⁇ of the hydrocarbons from the hydrocarbon feed valve 15 becomes longer, the time period in which the oxygen concentration around the active NO x * becomes higher becomes longer in the time period after the hydrocarbons are injected to when the hydrocarbons are next injected.
- the injection period ⁇ of the hydrocarbons becomes longer than about 5 seconds, the active NO x * starts to be
- the injection period ⁇ of the hydrocarbons has to be made 5 seconds or less.
- the injection period of the hydrocarbons is made from 0.3 second to 5 seconds.
- the NO x contained in the exhaust gas is reduced by the reducing intermediate which is held on the basic layer 53. Therefore, when the amount of the ⁇ contained in the exhaust gas increases, it is necessary to increase the amount of the reducing intermediate which is generated. To increase the amount of reducing intermediate which is generated, it is necessary to increase the amount of hydrocarbons which is fed per unit time from the hydrocarbon feed valve 15. To this end, it is necessary to increase the amount of injection of hydrocarbons from the hydrocarbon feed valve 15 or shorten the injection period ⁇ of the hydrocarbons from the hydrocarbon feed valve 15. In this case, if excessively increasing the amount of injection of
- the amount of hydrocarbons which slips through the exhaust purification catalyst 13 ends up increasing, so even if increasing the amount of injection of hydrocarbons from the hydrocarbon feed valve 15, there is a limit.
- the amount of injection of hydrocarbons from the hydrocarbon feed valve 15 cannot be made to change that greatly. Therefore, in an embodiment according to the present invention, as shown in FIG. 10B, the more the amount (mg/s) of the NO x contained in the exhaust gas increases, the shorter the injection period ⁇ of the hydrocarbons from the hydrocarbon feed valve 15 is made and thereby the more the amount of hydrocarbons which is fed per unit time is increased.
- the optimum injection amount and injection period of hydrocarbons from the hydrocarbon feed valve 15 for securing a good N0 X removal action by the first NO x removal method are found in advance.
- the optimum injection period ⁇ of the hydrocarbons at this time is also stored as a function of the amount Q of injection from the fuel injector 3 and engine speed N in the form of a map such as shown in FIG. 11B in advance in the ROM 32.
- FIG. llC schematically shows the value of the . injection period ⁇ which is stored in the map of FIG. 11B. Note that, the curves in FIG. 11C indicate
- the amount (mg/s) of the NO x contained in the exhaust gas increases the more the amount Q of injection from the fuel injector 3 increases, that is, the more the engine load increases, and
- the injection period ⁇ is made shorter the more the amount Q of injection from the fuel injector 3 increases and is made shorter the higher the engine speed N.
- an N0 X purification method when making the exhaust purification catalyst 13 function as an NO x storage catalyst will be explained specifically.
- the NO x purification method in the case of making the exhaust purification catalyst 13 function as an NO x storage catalyst in this way will be referred to below as the "second N0 X removal method”.
- the air-fuel ratio (A/F) in of the exhaust gas flowing into the exhaust purification catalyst 13 is temporarily made rich. If the air-fuel ratio (A/F) in of the exhaust gas is made rich, the NO x which was stored in the basic layer 53 when the air-fuel ratio (A/F) in of the exhaust gas was lean is released from the basic layer 53 all at once and reduced. Due to this, the N0 X is removed.
- the stored NO x amount ⁇ is, for example, calculated from the amount of N0 X which is exhausted from the engine.
- the exhausted NO x amount NOXA of NO x which is exhausted from the engine per unit time is stored as a function of the injection amount Q and engine speed N in the form of a map such as shown in FIG. 13 in advance in the ROM 32.
- the stored NO x amount ⁇ is calculated from this exhausted NO x amount NOXA.
- the period at which the air-fuel ratio (A/F) in of the exhaust gas is made rich is usually 1 minute or more.
- purification catalyst 13 is made rich. Note that, in FIG. 14, the abscissa indicates the crank angle. This
- injection amount Q and engine speed N in the form of a map such as shown in FIG. 15 in advance in the ROM 32.
- the injection amount of hydrocarbons from the hydrocarbon feed valve 15 increase so as to make the air-fuel ratio (A/F) in of the exhaust gas rich.
- the second NO x removal method is used, while if the catalyst temperature TC is high, the first ⁇ removal method is used.
- the stored N0 X is released from the exhaust purification catalyst 13 and reduced by making the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 13 rich.
- a large amount of reducing agent becomes necessary to make the N0 X which was once stored in the exhaust purification catalyst 13 be released from the exhaust purification catalyst 13 and be reduced in this way.
- the amount of reducing agent which is required for releasing the stored NO x from the exhaust purification catalyst 13 and reduce it in the second NO x removal method is larger compared with the amount of hydrocarbons, that is, the amount of reducing agent, which is required for generating the reducing intermediate in the first NO x removal method. That is, the amount of reducing agent which is required for removing the NO x is greater in the case of using the second NO x removal method compared with the case of using the first NO x removal method. Therefore, it is preferable to use the first NO x removal method as much as possible.
- the second NO x removal method when the catalyst temperature TC is low, the second NO x removal method is used, while when the catalyst temperature TC is high, the first NO x removal method is used. Therefore, in an embodiment according to the present invention, if the catalyst temperature TC becomes high, an ⁇ removal method is switched from the second NO x removal method to the first NO x removal method. In this case, as explained above, it is preferable to use the first NO x removal method as much as possible, so the temperature of the exhaust purification catalyst when an NO x removal method is switched from the second NO x removal method to the first NO x removal method is preferably as low as possible.
- the abscissa shows the amount (mg/s) of NO x per unit time which is contained in the exhaust gas. That is, as explained above, in the first NO x removal method, the NO x contained in the exhaust gas is reduced by the reducing intermediate which is held on the basic layer 53. Therefore, when the amount of the NO x contained in the exhaust gas increases, it is
- the allowable lower limit temperature ST of the exhaust purification catalyst 13 where there is no danger of the NO x being stored in the basic layer even if injecting hydrocarbons from the hydrocarbon feed valve 15 for performing the NO x removal action by the first NO x removal method that is, the allowable lower limit temperature ST of the exhaust purification catalyst 13 where a good NO x removal rate is obtained even if injecting hydrocarbons from the
- hydrocarbon feed valve 15 for performing the NO x removal action by the first NO x removal method becomes higher the smaller the amount (mg/s) of the ⁇ which is contained in the exhaust gas.
- this allowable lower limit temperature ST of the exhaust purification catalyst 13 is made the switching temperature from the second NO x removal method to the first NO x removal method. Therefore, in an embodiment according to the present invention, the
- switching temperature ST from the second NO x removal method to the first NO x removal method, as shown in FIG. 16, is made lower the greater the amount of NO x in the exhaust gas which flows into the exhaust purification catalyst 13.
- the exhaust purification catalyst 13 has a catalyst-specific lower limit
- This catalyst-specific lower limit temperature ST 0 becomes a constant temperature which is determined in accordance with the exhaust purification catalyst 13.
- the exhaust purification catalyst 13 has a purification rate drop start
- this removal rate drop start temperature TCI is used as the catalyst-specific lower limit temperature STo-
- purification catalyst 13 increases, at the NO x amount SN, the allowable lower limit temperature ST, that is, the switching temperature ST, matches the catalyst-specific lower limit temperature ST 0 .
- the catalyst 13 is smaller than the NO x amount SN which corresponds to the boundary between the allowable lower limit temperature ST and the catalyst-specific lower limit temperature ST 0 , that is, when the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13 is in the range of change at a small amount side within the range of change of the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13.
- the catalyst-specific lower limit temperature STo also expresses the switching temperature ST at which an NO x removal method is switched from the second NO x removal method to the first NO x removal method. Therefore, in the embodiment shown in FIG.
- the switching- temperature ST falls if the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13 increases when the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13 is in the range of change at a small amount side within the range of change of the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13, and the switching temperature ST is maintained at the catalyst-specific lower limit temperature ST 0 if the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13 becomes greater than the NO x amount SN which corresponds to the boundary between the allowable lower limit temperature ST and the catalyst-specific lower limit temperature ST 0 , that is, becomes greater than the above-mentioned small amount side range of change.
- a temperature TC2 which is lower than the removal rate drop start temperature TCI shown in FIG. 16 is used.
- This temperature TC2, as shown in FIG. 5, is the catalyst temperature TC at which the NO x removal rate Rl becomes 50 percent or less. Therefore, in the embodiment shown in FIG. 17, when the amount of NO x is large, even if the catalyst temperature TC is low as compared with the embodiment shown in FIG. 16, the first NO x removal method is used.
- the lower limit temperature STo expresses the switching temperature ST at which an NO x removal method is switched from the second NO x removal method to the first NO x removal method. Therefore, in the embodiment shown in FIG. 17 as well, the lower limit temperature STo expresses the switching temperature ST at which an NO x removal method is switched from the second NO x removal method to the first NO x removal method. Therefore, in the embodiment shown in FIG. 17 as well, the lower limit temperature STo expresses the switching temperature ST at which an NO x removal method is switched from the second NO x removal method to the first NO x removal method. Therefore, in the embodiment shown in FIG.
- the switching temperature ST falls if the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13 increases when the amount of N0 X in the exhaust gas flowing into the exhaust purification catalyst 13 is in the range of change at a small amount side within the range of change of the amount of N0 X in the exhaust gas flowing into the exhaust purification catalyst 13, and the switching temperature ST is maintained at the catalyst-specific lower limit temperature ST 0 if the amount of N0 X in the exhaust gas flowing into the exhaust purification catalyst 13 becomes greater than the NO x amount SN corresponding to the boundary between the allowable lower limit temperature ST and the catalyst-specific lower limit temperature ST 0 , that is, becomes greater than the above-mentioned small amount side range of change.
- the second NO x removal method is used, while when the catalyst temperature TC is higher than the switching temperatures ST and ST 0 , the first NO x removal method is used.
- a NO x removal method switching means is provided for switching an NO x removal method from the second NO x removal method to the first NO x removal method when the temperature of the exhaust purification catalyst 13 rises and exceeds a predetermined switching
- This NO x removal method switching means controls the switching temperature ST in accordance with the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13 which amount of NO x changes in accordance with the engine operating state.
- the electronic control unit 30 constitutes the ⁇ removal method switching means.
- the switching temperature ST of the exhaust purification catalyst 13 at which temperature an ⁇ removal method is switched from the second NO x removal method to the first NO x removal method is made gradually higher as shown by ST1, ST2, and ST3 if the oxygen concentration in the exhaust gas flowing into the exhaust purification catalyst 13 becomes higher.
- This base air-fuel ratio AFB is stored as a function of the amount Q of injection from the fuel injector 3 and the engine speed N in the form of a map such as shown in FIG. 19A in advance in the ROM 32.
- the switching temperature ST of the exhaust purification catalyst at which temperature an NO x removal method is switched from the second NO x removal method to the first ⁇ removal method is made higher as the base air-fuel ratio AFB becomes higher.
- FIG. 20 shows the timing of injection of additional fuel WR, the timing of injection of
- FIG. 21 shows the NO x purification control routine in the case of switching between the first NO removal method and the second NO x removal method at the switching temperatures ST and ST 0 which are shown by the solid lines . in FIG. 16 or FIG. 17. This routine is executed by interruption every fixed time interval.
- step 60 the amount NOXA of NO x exhausted per unit time is calculated from the map shown in FIG. 13.
- step 61 the switching temperatures ST and STo are calculated based on this amount NOXA of NO x exhausted per unit time from the relationship shown in FIG. 16 or FIG. 17.
- the routine proceeds to step 62 where it is judged if the catalyst temperature TC of the exhaust purification catalyst 13 which is calculated based on the detection signal from the temperature sensor 23 is lower than the switching temperatures ST and ST 0 .
- the routine proceeds to step 63 where the N0 X removal action by the second NO x removal method is performed.
- step 63 the amount NOXA of NO x exhausted per unit time is added to ⁇ to thereby calculate the stored NO x amount ⁇ .
- step 64 it is judged if the stored NO x amount ⁇ 0 ⁇ exceeds the allowable value MAX.
- the routine proceeds to step 65 where the additional amount of fuel WR is calculated from the map shown in FIG. 15 and the action of injection of additional fuel from the fuel injector 3 is performed. At this time, the air-fuel ratio of the exhaust gas flowing into the exhaust purification
- step 67 it is judged if the catalyst temperature TC has now become higher than the switching temperatures ST and ST 0 .
- the routine proceeds to step 68 where it is judged if the stored NO x amount ⁇ is smaller than a constant value MIN. Note that, this constant value MIN is made a value considerably smaller than the allowable value MAX.
- step 69 it is judged at step 68 that the stored NO x amount ⁇ NOX is larger than the constant value MIN.
- step 69 to release and reduce the stored ⁇ , the additional fuel WR corresponding to the stored
- step 71 the NO x removal action by the first NO x removal method is performed.
- hydrocarbons are injected from the hydrocarbon feed valve 15 in an amount WT which is calculated from the map shown in FIG. 11A by the injection period ⁇ which is calculated from the map which is shown in FIG. 11B.
- FIG. 22 shows the NO x purification control routine in the case of correcting the switching
- step 80 the amount NOXA of ⁇ exhausted per unit time is calculated from the map which is shown in FIG. 13.
- step 81 the base air-fuel ratio AFB is calculated from the map which is shown in FIG. 19A.
- step 82 the amount of rise AST of the switching temperature ST corresponding to the base air-fuel ratio AFB is calculated from the relationship shown in FIG. 19B.
- step 83 the amount of rise AST is added to the switching temperatures ST and ST 0 which are calculated from the relationship shown in FIG. 18 based on the amount NOXA of NO x exhausted per unit time to thereby calculate the final switching temperatures ST and ST 0 .
- step 84 it is judged if the catalyst temperature TC of the exhaust purification catalyst 13 which is
- step 85 the routine proceeds to step 85 where the NO x removal action by the second NO x removal method is performed.
- step 85 the amount NOXA of NO x exhausted per unit time is added to ⁇ to thereby calculate the stored NO x amount ⁇ .
- step 86 it is judged if the stored NO x amount ⁇ exceeds the allowable value MAX.
- the routine proceeds to step 87 where the additional amount of fuel WR is calculated from the map shown in FIG. 15 and the action of injection of additional fuel from the fuel injector 3 is performed. At this time, the air-fuel ratio of the exhaust gas flowing into the exhaust purification
- step 84 when it is judged at step 84 that the catalyst temperature TC becomes higher than the switching temperatures ST and ST 0 , the routine proceeds to step 89 where it is judged if the catalyst temperature TC has now become higher than the switching temperatures ST and ST 0 .
- step 89 the catalyst temperature TC has now become higher than the switching temperatures ST and ST 0
- the routine proceeds to step 90 where it is judged if the stored NO x amount ⁇ is smaller than the constant value MIN.
- the routine proceeds to step 91.
- step 91 to release and reduce the stored NO x , additional fuel WR corresponding to the stored NO x amount ⁇ is fed from the fuel injector 3, and the air- fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 13 is temporarily made rich.
- step 92 ⁇ is cleared.
- the routine proceeds to step 93 where the NO x removal action by the first NO x removal method is performed.
- hydrocarbons are injected from the hydrocarbon feed valve 15 in an amount WT which is calculated from the map shown in FIG. 11A by the injection period ⁇ which is calculated from the map shown in FIG. 11B.
- FIG. 24 shows the change in the exhaust gas flow rate GW (g/s), the change of the inflowing NO x amount NW (g/s) which flows into the exhaust purification catalyst 13, and the change of the outflowing NO x amount MW (g/s) which flows out from the exhaust purification catalyst 13 when an acceleration operation is performed.
- the exhaust gas flow rate GW rapidly increases, the inflowing N0 X amount NW rapidly increases, and, along with the increase in the inflowing N0 X amount NW, the outflowing NO x amount MW increases.
- the dash and dotted line A in the outflowing NO x amount MW of FIG. 24 shows the change in the outflowing NO x amount MW in the case of injecting hydrocarbons from the hydrocarbon feed valve 15 by the injection period ⁇ at the time of steady state operation which is stored in the map of FIG. 11B.
- the state of injection of hydrocarbons from the hydrocarbon feed valve 15 at this time is shown in FIG. 25A. From FIG.
- the exhaust gas flow rate GW is large, and at this time, even if injecting hydrocarbons from the hydrocarbon feed valve 15 by the injection period ⁇ at the time of steady state operation which is stored in the map of FIG. 11B, the amount of hydrocarbons is not sufficient for reducing the large amount of NO x which is contained in the exhaust gas at this time. Therefore, at this time, a considerable amount of NO x slips through the exhaust purification catalyst 13. Therefore, as shown in FIG. 24 by the dash and dotted line A, the outflowing NO x amount M becomes considerably large. In this case, to decrease the outflowing NO x amount MW, the amount of injection per unit time from the hydrocarbon feed valve 15 has to be increased.
- outflowing NO x amount MW of FIG. 24 shows the case of increasing the amount of injection per unit time from the hydrocarbon feed valve 15 by increasing the amount of injection of hydrocarbons as shown in FIG. 25B. As will be understood from FIG. 24, in this case, the outflowing NO x amount MW does not change that much from the
- the solid line C in the outflowing NO x amount MW of FIG. 24, shows the case of increasing the amount of injection per unit time from the hydrocarbon feed valve 15 by shortening the injection period ⁇ of the hydrocarbons to ⁇ as shown in FIG. 25C.
- the outflowing N0 X amount MW considerably decreases. That is, when the exhaust gas flow rate GW is large and, therefore, the flow rate of the exhaust gas flowing through the inside of the exhaust purification catalyst 13 is fast, a sufficient reaction time can no longer be secured
- the amount of generation of reducing intermediate is decreased. If the amount of generation of the reducing intermediate is decreased, the reducing intermediate reduces the NO x and is consumed a short time after generation. At this time, if shortening the
- FIG. 26A and FIG. 26B show the former method, that is, the method of setting the injection period ⁇ of the hydrocarbons short in the operating region which is normally gone through when an acceleration operation is performed. Note that, FIG. 26A shows equivalent injection period lines the same as in FIG. 11A, while FIG. 26B shows a map of the injection period ⁇ the same as the map shown in FIG. 11A.
- FIG. 26A shows by arrows the typical patterns of change in the amount Q of
- the injection period ⁇ of hydrocarbons in this high load medium-high speed region H is set shorter than the injection period ⁇ at an
- the injection period ⁇ in the high load medium-high speed region H which is normally gone through when an acceleration operation is performed is made shorter, so when an acceleration operation is performed, the injection period ⁇ is made shorter. Therefore, when an acceleration operation is performed, a good NO x purification rate can be secured.
- the injection period ⁇ of the hydrocarbons from the hydrocarbon feed valve 15 is made shorter when the amount of the exhaust gas flowing into the exhaust purification catalyst 13 is large compared to when the amount of the exhaust gas flowing into the exhaust purification catalyst 13 is small.
- hydrocarbons is shortened.
- FIG. 27 shows only the part changed for using the first example in FIG. 22.
- step 100 it is judged if the exhaust gas flow rate GW exceeds a
- the routine proceeds to step 80 where the amount NOXA of NO x exhausted per unit time is calculated from the map which is shown in FIG. 13.
- the routine proceeds to step 81 of FIG. 22.
- the routine proceeds to step 101 where the amount WT of injection of hydrocarbons from the hydrocarbon feed valve 15 at the time of steady state operation is calculated from the map shown in FIG. 11A.
- hydrocarbons is made the predetermined short injection period ⁇ such as shown in FIG. 25C. At this time, hydrocarbons are injected from the hydrocarbon feed valve 15 in an amount WTA of injection which was calculated at step 101 by the injection period ⁇ .
- hydrocarbons from the hydrocarbon feed valve 15 is shortened when the amount of NO x in the exhaust gas flowing into the exhaust purification catalyst 13 is large and the amount of the exhaust gas flowing into the exhaust purification catalyst 13 is large.
- the injection period ⁇ of the hydrocarbons is shortened when the inflowing NO x amount NW exceeds the predetermined inflowing NO x amount NX and the exhaust gas flow rate GW exceeds the
- FIG. 28 shows only the part changed for using the second example in FIG. 22.
- step 100 it is judged if the inflowing NO x amount NW exceeds a
- the routine proceeds to step 80 where the amount NOXA of NO x exhausted per unit time is calculated from the map shown in FIG. 13.
- the routine proceeds to step 81 of FIG. 22.
- the routine proceeds to step 101 where it is judged if the exhaust gas flow rate GW exceeds a predetermined exhaust gas flow rate GX.
- step 101 When it is judged at step 101 that the exhaust gas flow rate GW does not exceed the predetermined exhaust gas flow rate GX, the routine proceeds to step 80, then the routine proceeds to step 81 of FIG. 22. As opposed to this, when it is judged at step 101 that the exhaust gas flow rate GW exceeds the predetermined exhaust gas flow rate GX, the routine proceeds to step
- step 102 where the amount WT of injection of hydrocarbons from the hydrocarbon feed valve 15 at the time of steady state operation is calculated from the map shown in FIG. 11A.
- step 103 the injection period ⁇ of the
- hydrocarbons is made the predetermined short injection period ⁇ such as shown in FIG. 25C. At this time, hydrocarbons are injected from the hydrocarbon feed valve 15 in an amount WT of injection which was calculated at step 102 by the injection period ⁇ .
- FIG. 29 shows only the part changed for using the third example in FIG. 22.
- step 100 it is judged if an acceleration operation is being performed.
- the routine proceeds to step 80 where the amount NOXA of ⁇ exhausted per unit time is calculated from the map shown in FIG. 13.
- step 81 of FIG. 22 the routine proceeds to step 101 where the amount WT of injection of hydrocarbons from the hydrocarbon feed valve 15 at the time of steady state operation is calculated from the map shown in FIG. 11A.
- step 102 the injection period ⁇ of the hydrocarbons is made the predetermined short injection period ⁇ such as shown in FIG. 25C. At this time, hydrocarbons are injected from the hydrocarbon feed valve 15 in an amount WT of
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Abstract
Description
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Priority Applications (5)
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EP14747992.7A EP3039259B9 (en) | 2013-08-26 | 2014-07-03 | Exhaust purification system for an internal combustion engine |
US14/914,386 US9617893B2 (en) | 2013-08-26 | 2014-07-03 | Exhaust purification system for an internal combustion engine |
CN201480047457.6A CN105492733B (en) | 2013-08-26 | 2014-07-03 | Emission control system for internal combustion engine |
KR1020167004672A KR101707388B1 (en) | 2013-08-26 | 2014-07-03 | Exhaust purification system for an internal combustion engine |
RU2016106389A RU2625416C1 (en) | 2013-08-26 | 2014-07-03 | Exhaust control system for internal combustion engine |
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JP2013174637A JP5991285B2 (en) | 2013-08-26 | 2013-08-26 | Exhaust gas purification device for internal combustion engine |
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EP (1) | EP3039259B9 (en) |
JP (1) | JP5991285B2 (en) |
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CN107407179A (en) * | 2015-03-18 | 2017-11-28 | 五十铃自动车株式会社 | Emission control system |
CN107429591A (en) * | 2015-03-18 | 2017-12-01 | 五十铃自动车株式会社 | Emission control system |
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KR101704498B1 (en) | 2016-03-10 | 2017-02-09 | 자화전자(주) | Apparatus for auto focus with 3 location supporting structure |
CN114704353B (en) * | 2022-04-26 | 2023-05-23 | 潍柴动力股份有限公司 | Operation mode control method and device |
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ES2554637T3 (en) * | 2010-08-30 | 2015-12-22 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device for internal combustion engine |
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- 2013-08-26 JP JP2013174637A patent/JP5991285B2/en not_active Expired - Fee Related
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- 2014-07-03 WO PCT/JP2014/068374 patent/WO2015029612A1/en active Application Filing
- 2014-07-03 RU RU2016106389A patent/RU2625416C1/en not_active IP Right Cessation
- 2014-07-03 CN CN201480047457.6A patent/CN105492733B/en not_active Expired - Fee Related
- 2014-07-03 EP EP14747992.7A patent/EP3039259B9/en not_active Not-in-force
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Also Published As
Publication number | Publication date |
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CN105492733B (en) | 2017-11-17 |
JP5991285B2 (en) | 2016-09-14 |
EP3039259A1 (en) | 2016-07-06 |
EP3039259B1 (en) | 2017-09-13 |
US20160201538A1 (en) | 2016-07-14 |
KR101707388B1 (en) | 2017-02-15 |
KR20160029137A (en) | 2016-03-14 |
JP2015042857A (en) | 2015-03-05 |
CN105492733A (en) | 2016-04-13 |
EP3039259B9 (en) | 2018-03-28 |
RU2625416C1 (en) | 2017-07-13 |
US9617893B2 (en) | 2017-04-11 |
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