WO2012164713A1 - 内燃機関の制御装置 - Google Patents
内燃機関の制御装置 Download PDFInfo
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- WO2012164713A1 WO2012164713A1 PCT/JP2011/062672 JP2011062672W WO2012164713A1 WO 2012164713 A1 WO2012164713 A1 WO 2012164713A1 JP 2011062672 W JP2011062672 W JP 2011062672W WO 2012164713 A1 WO2012164713 A1 WO 2012164713A1
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- pressure egr
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- scr catalyst
- urea
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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
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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]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D21/00—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas
- F02D21/06—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air
- F02D21/08—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air the other gas being the exhaust gas of engine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/0047—Controlling exhaust gas recirculation [EGR]
- F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
- F02D41/0055—Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/02—EGR systems specially adapted for supercharged engines
- F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
- F02M26/06—Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
- F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
- F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/45—Sensors specially adapted for EGR systems
- F02M26/46—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/45—Sensors specially adapted for EGR systems
- F02M26/46—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition
- F02M26/47—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition the characteristics being temperatures, pressures or flow rates
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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
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
- F02B29/04—Cooling of air intake supply
- F02B29/0406—Layout of the intake air cooling or coolant circuit
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/02—EGR systems specially adapted for supercharged engines
- F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
- F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
- F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
- F02M26/23—Layout, e.g. schematics
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/50—Arrangements or methods for preventing or reducing deposits, corrosion or wear caused by impurities
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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
- the present invention relates to a control device for an internal combustion engine provided with a urea SCR catalyst in an exhaust passage.
- An SCR (Selective Catalytic Reduction) catalyst is a catalyst that purifies nitrogen oxides by reducing nitrogen oxides (NOx) with ammonia (NH 3 ). SCR catalysts are starting to be adopted in diesel engines that emit a large amount of nitrogen oxides. The SCR catalyst is also called “NOx selective reduction catalyst”.
- This urea is converted into ammonia and carbon dioxide by hydrolysis in the urea SCR catalyst.
- Ammonia obtained by this hydrolysis reduces nitrogen oxides in the SCR catalyst (see, for example, Patent Document 1).
- the system for supplying urea water to the SCR catalyst in this way is also referred to as “urea SCR system”, and the SCR catalyst to which urea water is supplied is also referred to as “urea SCR catalyst”.
- the high-pressure EGR system connects a position upstream of the turbine disposed in the exhaust passage and upstream of the turbine and a downstream position of the compressor disposed in the intake passage by a high-pressure EGR pipe.
- the exhaust gas circulation system recirculates high-pressure exhaust gas (high-pressure EGR gas) to the intake passage through the high-pressure EGR pipe.
- the low pressure EGR system connects a position of the exhaust passage downstream of the turbine and a position of the intake passage upstream of the compressor by a low pressure EGR pipe, and sucks low pressure exhaust gas (low pressure EGR gas) through the low pressure EGR pipe.
- the high pressure EGR gas recirculated by the high pressure EGR system has a high temperature. Therefore, it is difficult to circulate a large amount of high-pressure EGR gas, for example, when the engine load is high.
- the temperature of the low-pressure EGR gas recirculated by the low-pressure EGR system is low. Therefore, even when a large amount of high-pressure EGR gas cannot be circulated, a large amount of low-pressure EGR gas can be circulated. As a result, the amount of NOx discharged from the engine can be reduced (see, for example, Patent Document 2).
- the low-pressure EGR gas contains water vapor generated by the combustion of fuel. Further, since sulfur and sulfur are contained in the fuel, the lubricating oil, etc., the low pressure EGR gas also contains sulfur oxide (SOx). For this reason, when the low pressure EGR gas is cooled by a low pressure EGR pipe, a low pressure EGR cooler disposed in the low pressure EGR pipe, an intake pipe, an intercooler disposed in the intake pipe, or the like, acidic condensed water is generated.
- SOx sulfur oxide
- This acidic condensate is divided into “parts constituting low-pressure EGR systems such as low-pressure EGR pipes, low-pressure EGR valves and low-pressure EGR coolers”, “intake system parts such as intake pipes, compressors and intercoolers” and combustion chamber walls (hereinafter referred to as these Are collectively referred to as “engine components”.),
- engine components such as low-pressure EGR pipes, low-pressure EGR valves and low-pressure EGR coolers
- intake system parts such as intake pipes, compressors and intercoolers” and combustion chamber walls
- a control device for an internal combustion engine of the present invention includes fuel supply means for supplying fuel to the engine, urea SCR catalyst, urea water supply means, low-pressure gas recirculation means, and control means. .
- the urea SCR catalyst is disposed in the exhaust passage of the engine.
- the urea SCR catalyst purifies nitrogen oxides by reducing nitrogen oxides contained in the exhaust gas discharged from the engine with ammonia generated from “urea water supplied to the urea SCR catalyst”.
- the urea water supply means supplies urea water to the urea SCR catalyst.
- the low pressure gas recirculation means includes a low pressure EGR pipe and a low pressure EGR valve.
- the low pressure EGR pipe constitutes a low pressure EGR passage that communicates the downstream position of the urea SCR catalyst in the exhaust passage and the intake passage of the engine.
- the low pressure EGR valve is interposed in the low pressure EGR pipe, and the opening degree is changed so as to change the cross-sectional area of the low pressure EGR passage.
- the control means controls the amount of fuel supplied from the fuel supply means to the engine based on a parameter representing the operating state of the engine.
- the control means controls the opening degree of the low pressure EGR valve based on a parameter representing an operating state of the engine.
- the control means controls the operating state of the engine so that “amount of ammonia estimated to be necessary for reducing nitrogen oxides contained in the exhaust gas” is generated in the urea SCR catalyst. Based on the parameter to be expressed, “nitrogen oxide reduction urea water supply control for controlling the amount of urea water supplied from the urea water supply means” is executed.
- control means includes (1) The amount of “acid condensed water generated by gas passing through the low pressure EGR passage and accumulated in the low pressure EGR passage and the intake passage” (acid condensed water amount) is based on a parameter representing the operating state of the engine. Estimated (2) It is determined whether or not a specific condition including a condition that the estimated amount of acidic condensed water is equal to or greater than a threshold acidic condensed water amount is satisfied, (3) When it is determined that the specific condition is satisfied, ammonia is discharged from the urea SCR catalyst in a state where the gas flowing out from the urea SCR catalyst passes through the low-pressure EGR passage and flows into the intake passage.
- the “amount of the urea water to be supplied from the urea water supply means” is set to an amount larger than the “amount required for the nitrogen oxide reduction urea water supply control”.
- Control (ammonia generation urea water supply control) is executed for a predetermined time.
- the predetermined time for executing the ammonia generation urea water supply control may be until a predetermined time has elapsed from the start of the control, and the amount of the acidic condensed water estimated from the start of the control. May be a time period until the time point becomes equal to or less than “a value that is smaller than the threshold acidic condensed water amount by a predetermined value”.
- the urea water supply control for nitrogen oxide reduction is executed, so that the urea SCR catalyst “corresponds to an amount necessary and sufficient for purifying NOx in the exhaust gas.
- the amount of urea water is supplied.
- NOx is purified.
- the estimated amount of acidic condensate is equal to or greater than the threshold amount of acid condensate, the possibility of corrosion of engine components increases.
- the device of the present invention determines that “the amount of urea water to be supplied from the urea water supply means” is “the nitrogen oxidation”. The amount is changed to a larger amount than the “required amount for the urea water supply control for product reduction”.
- the device of the present invention can reduce the possibility of corrosion of engine components.
- control means comprises: Determining that the specific condition is satisfied when the condition that the engine is in a deceleration operation state is further satisfied, and When the specific condition is satisfied, the fuel supply from the fuel supply means is stopped, and the low-pressure EGR valve opening is changed to a predetermined opening larger than the opening immediately before the specific condition is satisfied. Configured.
- the control means of the first aspect sets the low-pressure EGR valve opening as “just before the specific condition is satisfied.
- a predetermined opening larger than the opening (opening opening equal to or less than the fully opened opening and larger than the fully closed opening) whereby a large amount of gas containing ammonia flowing out from the urea SCR catalyst is taken into the intake passage To reflux.
- acidic condensed water can be neutralized within a short time.
- control device includes An exhaust throttle valve disposed at a position downstream of the connection position of the low-pressure EGR passage of the exhaust passage and changing a cross-sectional area of the exhaust passage;
- the control means includes When the specific condition is satisfied, the opening of the exhaust throttle valve is changed to a predetermined opening that is smaller than the opening immediately before the specific condition is satisfied.
- the control means of the first aspect is configured so that the exhaust throttle valve has a predetermined opening degree (all the opening degree smaller than the opening degree immediately before the specific condition is satisfied (all By changing to “closed opening that is greater than or equal to the closed opening and smaller than the fully opened opening”, a larger amount of “gas containing ammonia flowing out from the urea SCR catalyst” is returned to the intake passage through the low-pressure EGR passage. .
- a predetermined opening degree all the opening degree smaller than the opening degree immediately before the specific condition is satisfied
- the control device includes a supercharger and high-pressure gas recirculation means.
- the supercharger is a turbine disposed at a position upstream of the urea SCR catalyst in the exhaust passage, and a compressor rotated by the turbine, and is connected to the low pressure EGR passage in the intake passage. And a compressor disposed at a downstream position.
- the high-pressure gas recirculation means includes a high-pressure EGR pipe that constitutes a high-pressure EGR passage that communicates a position of the exhaust passage upstream of the turbine and a position of the intake passage downstream of the compressor, and the high-pressure EGR pipe And a high pressure EGR valve whose opening degree is changed so as to change the passage cross-sectional area of the high pressure EGR passage.
- the control means is configured to change the opening of the high-pressure EGR valve to a predetermined opening smaller than the opening immediately before the specific condition is satisfied when the specific condition is satisfied.
- the opening degree of the high pressure EGR valve is set to “from the opening degree immediately before the specific condition is satisfied when the specific condition is satisfied and the fuel supply is stopped. It is desirable to change to a smaller predetermined opening (closed opening that is equal to or greater than the fully closed opening and smaller than the fully opened opening). As a result, a larger amount of “a gas containing ammonia” is recirculated to the intake passage through the low-pressure EGR passage. As a result, acidic condensed water can be neutralized in a shorter time.
- control means includes Urea SCR catalyst bed temperature estimating means for estimating a urea SCR catalyst bed temperature, which is a bed temperature of the urea SCR catalyst, based on a parameter representing an operating state of the engine, and When the condition that the estimated urea SCR catalyst bed temperature is equal to or higher than the threshold urea SCR catalyst bed temperature is further satisfied, it is determined that the specific condition is satisfied.
- the control means determines that the specific condition is satisfied when the condition that the estimated urea SCR catalyst bed temperature is equal to or higher than the threshold urea SCR catalyst bed temperature is further satisfied. If configured, it is possible to avoid wasteful consumption of urea water.
- the control means includes Low-pressure EGR gas that has flowed out of the urea SCR catalyst by changing the opening of the low-pressure EGR valve based on a parameter that represents the operating state of the engine when the fuel is supplied from the fuel supply means to the engine. Is configured to execute low-pressure EGR gas recirculation control for causing the gas to flow into the intake passage.
- control means is It is configured to determine that the specific condition is satisfied when the condition that the flow rate of the gas passing through the low pressure EGR passage is equal to or higher than a predetermined threshold flow rate during the low pressure EGR gas recirculation control is further satisfied. .
- condition that the flow rate of the gas passing through the low pressure EGR passage is equal to or higher than a predetermined threshold flow rate is synonymous with the condition that the low pressure EGR rate is equal to or higher than the threshold low pressure EGR rate. That is, when determining whether or not the specific condition is satisfied, the control means may determine whether or not the flow rate of the gas passing through the low pressure EGR passage is equal to or higher than a threshold flow rate. It may be determined whether the rate is equal to or greater than a threshold low pressure EGR rate.
- control means is Urea SCR catalyst bed temperature estimating means for estimating a urea SCR catalyst bed temperature, which is a bed temperature of the urea SCR catalyst, based on a parameter representing an operating state of the engine, and When the condition that the estimated urea SCR catalyst bed temperature is equal to or higher than the threshold urea SCR catalyst bed temperature is further satisfied, it is determined that the specific condition is satisfied.
- the urea water supply control for ammonia generation is executed, so that it is possible to avoid wasteful consumption of the urea water.
- the second aspect of the device of the present invention is: A slip catalyst disposed at a position downstream of the connection position of the low pressure EGR passage of the exhaust passage and purifying ammonia; An exhaust throttle valve disposed at a position downstream of the connection position of the low pressure EGR passage of the exhaust passage and upstream of the slip catalyst and changing a passage cross-sectional area of the exhaust passage; Can be provided.
- the slip catalyst is a catalyst that purifies ammonia (oxidation catalyst). Even during the urea water supply control for nitrogen oxide reduction, ammonia that has not been consumed in the urea SCR catalyst may leak slightly from the urea SCR catalyst. In general, the slip catalyst is disposed to purify ammonia leaking during the nitrogen oxide reducing urea water supply control.
- the second aspect of the apparatus of the present invention executes urea water supply control for ammonia generation when fuel is supplied to the engine.
- the operating state of the engine becomes unstable.
- the opening degree of the exhaust throttle valve cannot be changed to the fully closed opening degree, a part of the “gas containing ammonia” flowing out from the urea SCR catalyst passes through the slip catalyst. Therefore, it is preferable that the urea water supply control for ammonia generation is executed when the slip catalyst is in a state capable of purifying ammonia.
- control means is A slip catalyst bed temperature estimating means for estimating a slip catalyst bed temperature which is a bed temperature of the slip catalyst based on a parameter representing an operating state of the engine; It is determined that the specific condition is satisfied when a condition that the estimated slip catalyst bed temperature is equal to or higher than a threshold slip catalyst bed temperature is further satisfied, and It is preferable that the opening of the exhaust throttle valve is set to an opening other than the fully closed opening when the specific condition is satisfied.
- control means comprises: Including an engine operation stop request occurrence determining means for determining whether an engine operation stop request for stopping operation of the engine has occurred, Stopping the fuel supply from the fuel supply means when the engine operation stop request is generated; and When the engine operation stop request is generated, it is determined that the specific condition is satisfied when the condition that the estimated acidic condensed water amount is equal to or greater than the threshold acidic condensed water amount is satisfied.
- the third aspect includes Motoring means for forcibly rotating the engine with external power until the estimated amount of acidic condensate from the time when the specific condition is satisfied becomes smaller than a motoring stop threshold value is provided.
- the fuel supply is stopped when the engine operation stop request is generated. Further, it is determined that the specific condition is satisfied when the condition that the estimated acidic condensate amount is equal to or greater than the threshold acidic condensate amount when an engine operation stop request is generated, and the motoring means determines that the specific condition is satisfied. And the urea water supply control for ammonia generation is executed. As a result, the “gas containing ammonia” flowing out from the urea SCR catalyst returns to the intake passage through the low pressure EGR passage. As a result, the acidic condensed water can be neutralized after the engine operation stop request is generated.
- control means comprises: Including an engine operation stop request occurrence determining means for determining whether an engine operation stop request for stopping operation of the engine has occurred, When the engine operation stop request is generated, it is determined that the specific condition is satisfied when the condition that the estimated acidic condensed water amount is equal to or greater than the threshold acidic condensed water amount is satisfied.
- control means is The engine is continuously operated by continuously supplying fuel from the fuel supply means to the engine until the estimated acidic condensate amount becomes smaller than an engine stop threshold value from the time when the specific condition is satisfied. .
- the specific condition when the condition that the estimated amount of acidic condensate is equal to or greater than the threshold amount of acid condensate when an engine operation stop request is generated, the specific condition is satisfied. Is determined to hold. Then, the operation of the engine is continued from the time when the specific condition is satisfied until the estimated amount of acidic condensate becomes smaller than the engine stop threshold, and the urea water supply control for ammonia generation is executed. As a result, the “gas containing ammonia” flowing out from the urea SCR catalyst returns to the intake passage through the low pressure EGR passage. As a result, the acidic condensed water can be neutralized after the engine operation stop request is generated.
- the control means of this aspect continues to supply the fuel so that the engine is idle-operated until the estimated acidic condensate amount becomes smaller than the engine stop threshold from the time when the specific condition is satisfied, and
- the low-pressure EGR cooler disposed in the low-pressure EGR passage has a bypass passage
- an appropriate amount of low-pressure EGR gas is allowed to pass through the bypass passage, and when the intercooler disposed in the intake passage includes the bypass passage, It is preferable to pass an appropriate amount of gas. According to this, since the excessive low pressure EGR gas does not flow into the engine, the idling operation can be continued stably.
- control means is Urea SCR catalyst bed temperature estimating means for estimating a urea SCR catalyst bed temperature, which is a bed temperature of the urea SCR catalyst, based on a parameter representing an operating state of the engine, and When the condition that the estimated urea SCR catalyst bed temperature is equal to or higher than the threshold urea SCR catalyst bed temperature is further satisfied, it is determined that the specific condition is satisfied.
- the urea water supply control for ammonia generation is executed, so that it is possible to avoid wasteful consumption of the urea water.
- ammonia is supplied to the low-pressure EGR passage and the intake passage by the urea water supply control for ammonia generation.
- the low-pressure EGR passage is scavenged by a gas that does not substantially contain ammonia, and after the scavenging of the low-pressure EGR passage, the intake passage becomes “fresh air and low-pressure.
- the operation of the engine is stopped in the stage before reaching the point of scavenging by “gas flowing in from the EGR passage”, at least ammonia remains in the intake passage.
- ammonia is released into the atmosphere.
- the control means comprises: Engine operation stop request occurrence determination means for determining whether or not an engine operation stop request for stopping operation of the engine has occurred; An ammonia residual determination means for determining whether or not ammonia generated by the ammonia generation urea water supply control remains in the intake passage when an engine operation stop request for stopping operation of the engine is generated; Is provided.
- control means includes The fuel supply so as to continue the operation of the engine in a state where the urea water is not supplied from the urea water supply means when the ammonia residual determination means determines that the ammonia remains in the intake passage.
- Ammonia removal control for continuously supplying fuel to the engine from the means is configured to be executed for a predetermined time.
- the operation of the engine is stopped when the ammonia remaining in the low pressure EGR passage and the intake passage decreases or does not remain. Therefore, it is possible to avoid a large amount of ammonia being released into the atmosphere when performing repair / inspection.
- the control means includes scavenging state estimation means.
- the scavenging state estimation means includes (1) Estimating a first gas amount that is an integrated amount of gas that has passed through the low-pressure EGR passage after execution stop of the urea water supply control for ammonia generation; (2) It is determined whether or not the estimated first gas amount is greater than or equal to the volume of the low pressure EGR passage. (3) A second gas amount that is an integrated amount of gas passing through the intake passage is estimated from the time when the estimated first gas amount becomes equal to or greater than the volume of the low pressure EGR passage.
- ammonia residual determination means If the estimated second gas amount is not greater than or equal to the volume of the intake passage when the engine operation stop request is generated, it is determined that the ammonia remains in the intake passage.
- control means When the estimated second gas amount becomes equal to or larger than the volume of the intake passage, the ammonia removal control is stopped and the operation of the engine is stopped.
- FIG. 1 is a schematic configuration diagram of an internal combustion engine to which a control device (first control device) for an internal combustion engine according to a first embodiment of the present invention is applied.
- FIG. 2 is a flowchart showing a program executed by the CPU of the first control device.
- FIG. 3 is a flowchart showing a program executed by the CPU of the first control device.
- FIG. 4 is a flowchart showing a program executed by the CPU of the first control device.
- FIG. 5 is a flowchart showing a program executed by the CPU of the first control device.
- FIG. 6 is a flowchart showing a program executed by the CPU of the first control device.
- FIG. 1 is a schematic configuration diagram of an internal combustion engine to which a control device (first control device) for an internal combustion engine according to a first embodiment of the present invention is applied.
- FIG. 2 is a flowchart showing a program executed by the CPU of the first control device.
- FIG. 3 is a flowchart showing a program executed
- FIG. 7 is a flowchart showing a program executed by the CPU of the control device (second control device) for the internal combustion engine according to the second embodiment of the present invention.
- FIG. 8 is a flowchart showing a program executed by the CPU of the second control device.
- FIG. 9 is a flowchart showing a program executed by the CPU of the second control device.
- FIG. 10 is a flowchart showing a program executed by the CPU of the second control device.
- FIG. 11 is a flowchart showing a program executed by the CPU of the control device (third control device) for the internal combustion engine according to the third embodiment of the present invention.
- FIG. 12 is a flowchart showing a program executed by the CPU of the third control device.
- FIG. 13 is a flowchart showing a program executed by the CPU of the third control device.
- FIG. 14 is a flowchart showing a program executed by the CPU of the control device (fourth control device) for the internal combustion engine according to the fourth embodiment of the present invention.
- FIG. 15 is a flowchart showing a program executed by the CPU of the fourth control apparatus.
- FIG. 16 is a flowchart showing a program executed by the CPU of the fourth control apparatus.
- FIG. 17 is a flowchart showing a program executed by the CPU of the fourth control apparatus.
- FIG. 1 shows a schematic configuration of an internal combustion engine 10 to which a control device for an internal combustion engine according to a first embodiment of the present invention (hereinafter also simply referred to as “first control device”) is applied.
- the engine 10 is an in-line four-cylinder diesel engine.
- the engine 10 includes an engine body 20, an intake system 30, an exhaust system 40, a high pressure EGR system 50, and a low pressure EGR system 60.
- the first control device includes an electric control device 90.
- the engine body 20 includes a crankcase part, a cylinder block part, and a cylinder head part.
- the engine main body 20 includes a plurality (four) of combustion chambers (cylinders) that are each composed of a piston top surface, a cylinder wall surface, and a lower surface of the cylinder head portion.
- a fuel injection valve 21 is disposed above each combustion chamber.
- Each fuel injection valve 21 is supplied with “high pressure fuel” from “a fuel injection pump (not shown) connected to a fuel tank (not shown)”.
- the fuel injection valve 21 is opened by an instruction signal from the electric control device 90, and high pressure fuel is injected into each combustion chamber.
- a motoring device 22 that rotates the engine body 20 with external power is attached to the engine body 20. That is, in response to the instruction signal (drive signal), the motoring device 22 forcibly rotates the engine 10 with electric power from a “battery (not shown)” included in the “vehicle (not shown) on which the engine 10 is mounted”. Can be done.
- the intake system 30 includes an intake manifold 31, an intake pipe 32, a high-pressure throttle valve 33, an intercooler 34, and a turbocharger compressor 35.
- the intake manifold 31 includes a plurality of branch portions 31a and a collective portion 31b in which the plurality of branch portions 31a are assembled. Each of the plurality of branch portions 31a is connected to each of the plurality of combustion chambers through an intake port.
- the intake pipe 32 is connected to the collective portion 31 b of the intake manifold 31.
- the intake manifold 31 and the intake pipe 32 constitute an intake passage.
- the high pressure throttle valve 33 is disposed at a predetermined position of the intake pipe 32.
- the high pressure throttle valve 33 is rotatably supported by the intake pipe 32.
- the high-pressure throttle valve 33 is rotated to change the passage sectional area of the intake passage formed by the intake pipe 32.
- the high-pressure throttle valve actuator 33a rotates the high-pressure throttle valve 33 in response to an instruction signal (drive signal).
- the intercooler 34 is disposed at a position upstream of the high-pressure throttle valve 33 in the intake pipe 32.
- the intercooler 34 cools the gas flowing through the intake pipe 32.
- the compressor 35 is disposed at a position upstream of the intercooler 34 in the intake pipe 32.
- the compressor 35 rotates with a turbine 43 described later, and compresses the gas flowing through the intake pipe 32.
- the exhaust system 40 includes an exhaust manifold 41, an exhaust pipe 42, a turbocharger turbine 43, a urea SCR catalyst 44, a slip catalyst 45, a urea water addition valve (urea water supply means) 46, and an exhaust throttle valve 47.
- the exhaust manifold 41 includes a plurality of branch portions 41a and a collective portion 41b in which the plurality of branch portions 41a are aggregated. Each of the plurality of branch portions 41a is connected to each of the plurality of combustion chambers through an exhaust port.
- the exhaust pipe 42 is connected to the collecting portion 41 b of the exhaust manifold 41.
- the exhaust manifold 41 and the exhaust pipe 42 constitute an exhaust passage.
- the turbine 43 is disposed at a predetermined position of the exhaust pipe 42.
- the turbine 43 is rotated by high-temperature and high-pressure exhaust gas to rotate the compressor 35.
- the urea SCR catalyst 44 is disposed at a “position downstream of the turbine 43” of the exhaust pipe 42 (exhaust passage). As described later, urea water is supplied to the urea SCR catalyst 44. When the bed temperature of the urea SCR catalyst 44 is equal to or higher than the threshold urea SCR catalyst bed temperature, the urea water is hydrolyzed in the urea SCR catalyst 44 as shown in the formula (1), and ammonia (NH 3 ) and Converted to carbon dioxide.
- the urea SCR catalyst 44 when the bed temperature of the urea SCR catalyst 44 is equal to or higher than the threshold urea SCR catalyst bed temperature, the urea SCR catalyst 44 reduces nitrogen oxides (NOx) with ammonia (NH 3 ) generated from the urea water. To purify nitrogen oxides.
- the urea SCR catalyst 44 includes a support made of ceramics and a zeolite catalyst supported on the support.
- the urea SCR catalyst may be a vanadium catalyst.
- the slip catalyst 45 is disposed in a “position downstream of the urea SCR catalyst 44” of the exhaust pipe 42 (exhaust passage).
- the slip catalyst 45 is an oxidation catalyst that purifies ammonia when the bed temperature is equal to or higher than the threshold slip catalyst bed temperature.
- the urea water addition valve 46 is disposed at “a position upstream from the urea SCR catalyst 44” and “a position downstream from the turbine 43” in the exhaust pipe 42 (exhaust passage).
- the urea water addition valve 46 is connected to a urea water tank, a pressurizing device, and the like (not shown).
- the urea water addition valve 46 constitutes urea water supply means for supplying urea water to the urea SCR catalyst 44 in accordance with an instruction.
- the exhaust throttle valve 47 is disposed at a “position downstream of the urea SCR catalyst 44” and a “position upstream of the slip catalyst 45” of the exhaust pipe 42 (exhaust passage).
- the exhaust throttle valve 47 is configured to change the cross-sectional area of the exhaust passage formed by the exhaust pipe 42 by changing the opening degree thereof.
- the exhaust throttle valve actuator 47a changes the opening degree of the exhaust throttle valve 47 in response to the instruction.
- the high pressure EGR system 50 includes a high pressure EGR pipe 51 and a high pressure EGR valve 52.
- One end of the high-pressure EGR pipe 51 is connected to a collecting portion 41b of the exhaust manifold 41 (that is, a position upstream of the turbine 43 in the exhaust passage).
- the other end of the high pressure EGR pipe 51 is connected to a “position downstream of the high pressure throttle valve 33” of the intake pipe 32 (intake passage).
- the high pressure EGR pipe 51 forms a high pressure EGR passage that communicates the position upstream of the turbine 43 in the exhaust passage and the downstream position of the compressor 35 in the intake passage.
- the high pressure EGR valve 52 is disposed in the high pressure EGR pipe 51.
- the high pressure EGR valve 52 is configured to change the passage cross-sectional area of the high pressure EGR passage formed by the high pressure EGR pipe 51 by changing the opening degree thereof.
- the high pressure EGR valve actuator 52a changes the opening degree of the high pressure EGR valve 52 in accordance with an instruction. When the high-pressure EGR valve 52 is fully closed, the cross-sectional area of the high-pressure EGR passage becomes “0”.
- the low pressure EGR system 60 includes a low pressure EGR pipe 61, a low pressure EGR cooler 62, and a low pressure EGR valve 63.
- One end of the low pressure EGR pipe 61 is connected to the “position downstream of the urea SCR catalyst 44 and upstream of the exhaust throttle valve 47” of the exhaust pipe 42 (exhaust passage).
- the other end of the low pressure EGR pipe 61 is connected to the “position upstream of the compressor 35” of the intake pipe 32 (intake passage).
- the low-pressure EGR pipe 61 forms a low-pressure EGR passage that connects the downstream position of the urea SCR catalyst 44 in the exhaust passage and the intake passage (position upstream of the compressor 35 in the intake passage).
- the low pressure EGR cooler 62 is disposed in the low pressure EGR pipe 61.
- the low pressure EGR cooler 62 cools the gas flowing through the low pressure EGR pipe 61.
- the low-pressure EGR valve 63 is disposed in the low-pressure EGR pipe 61 “a position downstream of the low-pressure EGR cooler 62 with respect to the flow of gas flowing in the low-pressure EGR pipe 61”.
- the low pressure EGR valve 63 is configured to change the passage cross-sectional area of the low pressure EGR passage formed by the low pressure EGR pipe 61 by changing the opening degree thereof.
- the low pressure EGR valve actuator 63a changes the opening degree of the low pressure EGR valve 63 in accordance with an instruction. When the low-pressure EGR valve 63 is fully closed, the cross-sectional area of the low-pressure EGR passage becomes “0”.
- the first control device includes an air flow meter (fresh air flow sensor) 71, an intake pressure sensor (supercharging pressure sensor) 72, an intake air temperature sensor 73, a cooling water temperature sensor 74, an engine speed sensor 75, a NOx sensor 76, a low pressure.
- An EGR valve downstream pressure sensor 77, a low pressure EGR valve upstream pressure sensor 78, a low pressure EGR gas temperature sensor 79, and an accelerator pedal operation amount sensor 80 are provided.
- the air flow meter 71 is disposed in the intake pipe 32 (intake passage).
- the air flow meter 71 generates a signal Ga representing a “new air flow rate” which is a mass flow rate (air amount per unit time) of air (fresh air) passing through the intake passage.
- the intake pressure sensor 72 detects the gas pressure at a position downstream of the high-pressure throttle valve 33 in the intake pipe 32 and generates a signal P indicating the supercharging pressure.
- the intake air temperature sensor 73 detects a gas temperature (intake air temperature) at a position downstream of the high-pressure throttle valve 33 in the intake pipe 32 and generates a signal THA indicating the intake air temperature.
- the coolant temperature sensor 74 detects the coolant temperature (coolant coolant temperature) of the engine 10 and generates a signal THW indicating the coolant temperature.
- the engine rotation speed sensor 75 detects the rotation speed of the internal combustion engine 10 and generates a signal representing the engine rotation speed NE.
- the NOx sensor 76 is disposed at the “position downstream of the urea SCR catalyst 44” of the exhaust pipe 42 (exhaust passage) and at the “position upstream of the connection position between the low pressure EGR pipe 61 and the exhaust pipe 42”. ing.
- the NOx sensor 76 is a so-called limit current type NOx sensor (see, for example, JP 2010-71195 A, JP 2009-46992 A, and JP 2003-120399 A).
- the NOx sensor 76 outputs an output value DNOx corresponding to “the total concentration of NOx concentration and ammonia concentration” contained in the gas reaching the NOx sensor 76.
- the NOx sensor 76 decomposes NOx (mainly NO) into N 2 and O 2 therein, and outputs an output value DNOx proportional to the decomposed O 2 concentration to a limiting current type oxygen. It occurs based on the same principle as the density sensor. Further, the NOx sensor 76 decomposes NH 3 (ammonia) into NO and H 2 O in the inside thereof, further decomposes the NO into N 2 and O 2, and is proportional to the concentration of the decomposed O 2. The generated output value DNOx is generated based on the same principle as that of the limiting current type oxygen concentration sensor.
- the output value DNOx changes in proportion to the NOx concentration.
- the output value DNOx changes in proportion to the ammonia concentration.
- the low pressure EGR valve downstream pressure sensor 77 detects the gas pressure (low pressure EGR valve downstream pressure) at the “position downstream of the low pressure EGR valve 63” of the low pressure EGR pipe 61, and outputs a signal Pd indicating the low pressure EGR valve downstream pressure. It is supposed to occur.
- the low pressure EGR valve upstream pressure sensor 78 detects the gas pressure (low pressure EGR valve upstream pressure) at the “position upstream of the low pressure EGR valve 63” of the low pressure EGR pipe 61 and outputs a signal Pu indicating the low pressure EGR valve upstream pressure. It is supposed to occur.
- the low-pressure EGR gas temperature sensor 79 detects the gas temperature (low-pressure EGR valve upstream temperature) at the “position upstream of the low-pressure EGR valve 63” of the low-pressure EGR pipe 61 and generates a signal Tu indicating the low-pressure EGR valve upstream temperature. It is supposed to be.
- the accelerator pedal operation amount sensor 80 detects the operation amount of the accelerator pedal AP and generates a signal Accp indicating the accelerator operation amount.
- the electric control device 90 includes a “CPU, ROM, RAM, a backup RAM that stores data while the power is on and holds the stored data even when the power is shut off, an interface including an AD converter, etc. Is a known microcomputer.
- the interface of the electric control device 90 is connected to the sensors 71 to 80, and supplies signals from the sensors 71 to 80 to the CPU. Further, the interface is connected to each fuel injection valve 21, the high-pressure throttle valve actuator 33a, the urea water addition valve 46, the exhaust throttle valve actuator 47a, the high-pressure EGR valve actuator 52a, the low-pressure EGR valve actuator 63a, and the like according to instructions from the CPU. An instruction (instruction signal, drive signal) is transmitted.
- the CPU of the first control device determines the fuel injection amount based on the signal Accp indicating the accelerator operation amount and the engine rotational speed NE, and the determined fuel injection amount is injected (supplied) into each combustion chamber. In addition, an instruction signal is sent to the fuel injection valve 21. However, the CPU determines that the operation state of the engine 10 is in the decelerating operation state based on an engine operation parameter (for example, accelerator pedal operation amount Accp and engine rotation speed NE) that is a parameter representing the operation state of the engine 10. At this time, the fuel injection is stopped (fuel supply is stopped).
- an engine operation parameter for example, accelerator pedal operation amount Accp and engine rotation speed NE
- the CPU determines a target high pressure EGR rate based on engine operating parameters (for example, the fuel injection amount Q and the engine speed NE), and the high pressure EGR valve actuator so that the target high pressure EGR rate is realized.
- An instruction signal is sent to 52a.
- the CPU determines a target low pressure EGR rate based on engine operating parameters (for example, fuel injection amount Q and engine rotational speed NE), and a low pressure EGR valve actuator so that the target low pressure EGR rate is realized.
- An instruction signal is sent to 63a.
- the CPU determines a target exhaust throttle opening based on engine operating parameters (for example, fuel injection amount Q and engine rotational speed NE) so that the target exhaust throttle opening is realized.
- An instruction signal is sent to the exhaust throttle valve actuator 47a.
- the CPU should supply the “urea SCR catalyst 44 necessary and sufficient for reducing NOx in the exhaust gas based on the engine operation parameters (for example, the fuel injection amount Q and the engine speed NE) during normal operation.
- the amount of urea water is determined, and an instruction signal is sent to the urea water addition valve 46 so that the determined amount of urea water is supplied to the urea SCR catalyst 44.
- This control is also referred to as “nitrogen oxide reduction urea water supply control”.
- the amount of added urea water becomes an appropriate amount (that is, the output value DNOx is “0” and NOx and ammonia are discharged from the urea SCR catalyst 44).
- the amount of urea water supplied from the urea water addition valve 46 may be feedback-controlled so that it is not discharged).
- the gas passing through the low-pressure EGR passage contains water vapor and sulfur oxide SOx produced by “sulfur S contained in fuel and / or lubricating oil”. For this reason, when water vapor in the gas passing through the low pressure EGR passage is cooled when passing through the low pressure EGR cooler 62, the intercooler 34, and the like, condensed water is generated, and the condensed water is acidic condensed water by sulfur oxide SOx. It becomes. Acidic condensed water is accumulated in the low pressure EGR passage and the intake passage.
- the CPU estimates the amount of acidic condensed water (acid condensed water amount) as described later. Further, the CPU estimates the bed temperature of the urea SCR catalyst 44 (urea SCR catalyst bed temperature) based on engine operation parameters (for example, the fuel injection amount Q and the engine speed NE) as described later.
- the CPU determines (monitors) whether or not a specific condition described below (a start condition for starting the ammonia generation urea water supply control) is satisfied. This specific condition is satisfied when all the conditions described below are satisfied, and is not satisfied when at least one of the conditions described below is not satisfied.
- a specific condition described below a start condition for starting the ammonia generation urea water supply control
- the operating state of the engine 10 is in a “decelerated operation state in which fuel injection is stopped (decelerated fuel supply (injection) stop operation state)”.
- the urea SCR catalyst bed temperature is equal to or higher than the threshold urea SCR catalyst bed temperature.
- the estimated acidic condensed water amount is equal to or greater than the threshold acidic condensed water amount (ammonia generation urea water supply control start threshold).
- the condition 1-3 is an indispensable condition for satisfying the specific condition.
- the CPU supplies a predetermined amount of urea water from the urea water addition valve 46 to the urea SCR catalyst 44.
- the amount of urea water to be supplied to the urea SCR catalyst 44 for the nitrogen oxide reduction urea water supply control is “0”, the amount of urea water supplied to the urea SCR catalyst 44 at this time is , “Amount required for controlling supply of urea water for nitrogen oxide reduction”. It is preferable that the amount of urea water supplied at this time increases as the estimated urea SCR catalyst bed temperature increases.
- control for supplying urea water to cause ammonia to flow out from the urea SCR catalyst 44 is also referred to as “ammonia generation urea water supply control”.
- the CPU sets the low-pressure EGR valve 67 to “a predetermined opening larger than the opening immediately before the specific condition is satisfied (the opening side which is equal to or less than the fully opened opening and larger than the fully closed opening).
- the opening of the high pressure EGR valve 52 is “a predetermined opening smaller than the opening immediately before the specific condition is satisfied (the opening on the closing side is not less than the fully closed opening and smaller than the fully opened opening).
- the exhaust throttle valve 47 is “a predetermined opening smaller than the opening immediately before the specific condition is satisfied (the opening on the closed side is not less than the fully closed opening and smaller than the fully opened opening”).
- control valves such as the low pressure EGR valve 67, the high pressure EGR valve 52 and the exhaust throttle valve 47” are controlled to be fully opened, and the opening degree of the control valve is set to the maximum opening degree of the control valve.
- Setting to is synonymous.
- controlling the control valve to a fully closed state and setting the opening of the control valve to the minimum opening (“0”) of the valve are synonymous. Therefore, the opening degree of the control valve means that the opening degree of the control valve is equal to or less than a predetermined opening degree, and the passage cross-sectional area of the passage in which the control valve is interposed is smaller than a predetermined area. It is synonymous with setting to a small area.
- the opening degree of the control valve means that the opening degree of the control valve is equal to or larger than a predetermined opening degree, and the cross-sectional area of the passage in which the control valve is interposed is larger than a predetermined area. Is equivalent to setting a large area.
- urea water is supplied to the urea SCR catalyst 44, and ammonia is generated from the urea water.
- the generated ammonia flows out of the urea SCR catalyst 44 without being consumed in the urea SCR catalyst 44.
- most of the gas (gas containing generated ammonia) flowing out from the urea SCR catalyst 44 passes through the low pressure EGR passage. Therefore, the acidic condensed water staying in the parts constituting the low pressure EGR passage (low pressure EGR pipe 61, low pressure EGR cooler 62, low pressure EGR valve 63, etc.) is neutralized by ammonia. Further, the acidic condensed water staying in the parts constituting the intake passage (the intake pipe 32, the compressor 35, the intercooler 34, the high pressure throttle valve 33, the intake manifold 31, etc.) is neutralized by ammonia.
- the estimated amount of acidic condensed water is a ammonia generation urea water supply control end threshold (a value smaller than the ammonia generation urea water supply control start threshold by a predetermined value). It may be 0.)
- the supply of urea water to the urea SCR catalyst 44 is stopped.
- the CPU of the electric control device 90 repeatedly executes the control execution routine shown in FIG. 2 every elapse of a predetermined time. Therefore, when the predetermined timing comes, the CPU starts the process from step 200 in FIG. 2 and determines in step 205 whether or not the engine 10 is in a decelerating operation state. More specifically, the CPU determines that the engine 10 is in a decelerating operation state when the accelerator pedal operation amount Accp is “0” and the engine speed NE is equal to or greater than the threshold engine speed NEth.
- step 210 the command fuel injection amount Q is determined based on the accelerator pedal operation amount Accp and the engine rotational speed NE. To decide. The CPU may correct the commanded fuel injection amount Q in consideration of the smoke generation amount and the like.
- step 215 fuel is supplied to the fuel injection valve 21 of the fuel injection cylinder so that an amount of fuel corresponding to the determined instruction fuel injection amount Q is injected from the fuel injection valve 21 of the fuel injection cylinder. An injection instruction signal is sent out.
- a fuel injection cylinder is a cylinder that has reached the timing at which combustion should occur. Thereafter, the CPU proceeds to step 220.
- step 205 when the CPU determines that the engine 10 is in a decelerating operation state when the CPU executes the process of step 205, the CPU determines “Yes” in step 205 and proceeds directly to step 220. Accordingly, since step 215 is not executed, fuel injection is not executed (fuel supply is stopped) when the engine 10 is in the deceleration operation state.
- step 220 the CPU determines whether or not the value of the ammonia generation urea water supply control flag XNH3 (hereinafter simply referred to as “supply control flag XNH3”) is “0”.
- Supply control flag XNH3 is set to “0” in an initial routine that is executed when an ignition key switch (not shown) of a vehicle equipped with engine 10 is changed from the off position to the on position. Further, the value of the supply control flag XNH3 is set to “1” when the specific condition is satisfied by the “ammonia generation urea water supply control start determination routine” shown in FIG.
- step 220 makes a “Yes” determination at step 220 to sequentially perform the processing from step 225 to step 245 described below, and proceeds to step 295 to end the present routine tentatively.
- Step 225 The CPU calculates a target low pressure EGR rate and a target high pressure EGR rate based on the fuel injection amount Q and the engine rotational speed NE.
- Step 230 The CPU sends an instruction signal to the low pressure EGR valve actuator 63a so that the actual low pressure EGR rate (actual low pressure EGR rate) matches the target low pressure EGR rate, and controls the opening degree of the low pressure EGR valve 63.
- the CPU divides the actual low pressure EGR gas flow rate (the flow rate of the gas flowing through the low pressure EGR pipe 61) by the total gas amount (the total flow rate of the gas flowing into the engine 10), thereby obtaining the actual low pressure EGR gas flow.
- the rate (actual low pressure EGR rate) ⁇ LP is calculated. Further, the CPU may feedback control the opening degree of the low pressure EGR valve 63 so that the actual low pressure EGR rate ⁇ LP matches the target low pressure EGR rate.
- the CPU detects the actual low pressure EGR gas flow rate (low pressure EGR passage passage gas amount GLPEGR) by the low pressure EGR valve downstream pressure Pd and the low pressure EGR valve upstream pressure sensor 78 detected by the low pressure EGR valve downstream pressure sensor 77.
- the low-pressure EGR valve upstream pressure Pu, the low-pressure EGR valve upstream temperature Tu detected by the low-pressure EGR gas temperature sensor 79, and the opening degree of the low-pressure EGR valve 63 (instruction signal to the low-pressure EGR valve actuator 63a) Acquired based on the model formula that represents the behavior when passing. Further, the CPU acquires the total gas amount based on the supercharging pressure P detected by the intake pressure sensor 72, the intake air temperature THA detected by the intake air temperature sensor 73, and the engine speed NE.
- Step 235 The CPU sends an instruction signal to the high pressure EGR valve actuator 52a so that the actual high pressure EGR rate matches the target high pressure EGR rate, and controls the opening degree of the high pressure EGR valve 52.
- the CPU may feedback control the opening degree of the high pressure EGR valve 52 in the same manner as the feedback control of the low pressure EGR valve 63.
- Step 240 The CPU determines the target exhaust valve throttle opening based on the engine operating parameters (for example, the fuel injection amount Q and the engine rotational speed NE), and the actual exhaust throttle valve 47 opening degree is the target exhaust throttle valve opening.
- An instruction signal is sent to the exhaust throttle valve actuator 47a so as to match the degree, and the opening degree of the exhaust throttle valve 47 is controlled. Note that, during normal operation (when the specific condition is not satisfied), the CPU sets the opening of the exhaust throttle valve 47 to an opening on the opening side larger than “0” (an opening other than the fully closed opening). Set to.
- Step 245 The CPU determines “amount of ammonia necessary for purifying (reducing) NOx in the exhaust gas in the urea SCR catalyst 44” based on the engine operating parameters (for example, the fuel injection amount Q and the engine speed NE). Is determined as “the amount of urea water estimated to be necessary and sufficient for generation in the urea SCR catalyst 44”, and that amount of urea water is supplied from the urea water addition valve 46. That is, the CPU executes urea water supply control for nitrogen oxide reduction.
- the engine operating parameters for example, the fuel injection amount Q and the engine speed NE.
- the CPU sets the output value DNOx of the NOx sensor 76 to “0”, in other words, urea water supplied from the urea water addition valve 46 so that NOx and ammonia do not flow out from the urea SCR catalyst 44. May be feedback controlled.
- step 220 determines “No” in step 220, and steps 250 to 265 described below. These processes are performed in order, and the routine proceeds to step 295 to end the present routine tentatively.
- Step 250 The CPU determines that the opening of the low-pressure EGR valve 63 is “the opening just before the value of the supply control flag XNH3 changes from“ 0 ”to“ 1 ”(the opening immediately before the specific condition is satisfied). Is sent to the low pressure EGR valve actuator 63a so that the predetermined opening degree is larger (opening side opening degree, in this example, fully open state).
- Step 255 The CPU determines that the exhaust throttle valve 47 is smaller than the opening immediately before the value of the supply control flag XNH3 changes from “0” to “1” (opening immediately before the specific condition is satisfied). Is sent to the exhaust throttle valve actuator 47a so that the opening of the exhaust throttle valve actuator 47a is reached.
- Step 260 The CPU determines that the high-pressure EGR valve 52 is smaller than the opening immediately before the value of the supply control flag XNH3 changes from “0” to “1” (opening immediately before the specific condition is satisfied). Is sent to the high-pressure EGR valve actuator 52a so that the opening degree is (the opening degree on the closing side, which is the fully closed state in this example).
- Step 265 The CPU supplies a predetermined amount of urea water from the urea water addition valve 46. That is, the CPU executes urea water supply control for ammonia generation. At this time, the CPU may change the predetermined amount so that the predetermined amount increases as the urea SCR catalyst bed temperature separately estimated by a routine described later increases.
- the CPU executes the “ammonia-generating urea water supply control / start determination routine” shown by the flowchart in FIG. 3 every time a predetermined time elapses. Therefore, when the predetermined timing comes, the CPU starts the process from step 300 in FIG. 3 and proceeds to step 310 to determine whether or not the value of the supply control flag XNH3 is “0”.
- step 310 the CPU makes a “Yes” determination at step 310 to proceed to step 320 to read a urea SCR catalyst bed temperature TempSCR that is separately estimated by a routine described later.
- step 330 the CPU reads the acidic condensed water amount Sacidw estimated separately by a routine described later.
- step 340 the CPU determines whether or not the operation state of the engine 10 is “a deceleration operation state in which fuel injection is stopped (deceleration injection stop operation state)” (that is, the condition 1-1 is satisfied). Whether or not).
- the CPU determines whether or not the accelerator pedal operation amount Accp is “0” and the engine speed NE is equal to or higher than the threshold engine speed NEth.
- the CPU makes a “No” determination at step 340 to directly proceed to step 395 to end the present routine tentatively.
- the value of the supply control flag XNH3 is maintained at “0”.
- the CPU makes a “Yes” determination at step 340 to proceed to step 350 where the urea SCR catalyst bed temperature TempSCR is a threshold value. It is determined whether or not the temperature is equal to or higher than the urea SCR catalyst bed temperature TempSCRsth (that is, whether or not the condition 1-2 is satisfied).
- the threshold urea SCR catalyst bed temperature TempSCRsth is set to a temperature equal to or higher than the temperature at which urea water is sufficiently hydrolyzed into ammonia in the urea SCR catalyst 44.
- the CPU makes a “No” determination at step 350 to directly proceed to step 395 to end the present routine tentatively.
- the value of the supply control flag XNH3 is maintained at “0”.
- the CPU makes a “Yes” determination at step 350 to proceed to step 360 where the acidic condensed water amount Sacidw is equal to the threshold acidic condensed water amount. It is determined whether or not it is equal to or greater than Sacidwsth (that is, whether or not the condition 1-3 is satisfied).
- This amount of acidic condensed water Sacidwsth is “amount that is highly likely to cause corrosion of engine components” when acidic condensed water of an amount greater than the threshold acidic condensed water amount Sacidwsth stays in the low pressure EGR passage and the intake passage. Is set.
- the CPU makes a “No” determination at step 360 to directly proceed to step 395 to end the present routine tentatively.
- the value of the supply control flag XNH3 is maintained at “0”.
- the CPU makes a “Yes” determination at step 360 to proceed to step 370 to set the value of the supply control flag XNH3 to “1”. . Thereafter, the CPU proceeds to step 395 to end the present routine tentatively.
- step 310 When the value of the supply control flag XNH3 is set to “1” in this way and the CPU proceeds to step 310 again, the CPU makes a “No” determination at step 310 and proceeds directly to step 395. This routine is temporarily terminated. As a result, the value of the supply control flag XNH3 is maintained at “1”. Accordingly, the processing from step 250 to step 265 in FIG. 2 is performed, the urea water supply control for ammonia generation is executed, and the acidic condensed water is neutralized.
- the CPU executes the “ammonia generation urea water supply control / end determination routine” shown by the flowchart in FIG. 4 every time a predetermined time elapses. Therefore, when the predetermined timing comes, the CPU starts the process from step 400 in FIG. 4 and proceeds to step 410 to determine whether or not the value of the supply control flag XNH3 is “1”. At this time, if the value of the supply control flag XNH3 is “0”, the CPU makes a “No” determination at step 410 to directly proceed to step 495 to end the present routine tentatively.
- step 410 the CPU makes a “Yes” determination at step 410 to proceed to step 420, where the urea SCR catalyst bed temperature estimated separately by a routine to be described later. Read TempSCR.
- step 430 the CPU reads an acidic condensed water amount Sacidw estimated separately by a routine described later. The acidic condensed water amount Sacidw is gradually reduced when the ammonia generation urea water supply control is executed (when the value of the supply control flag XNH3 is “1”).
- step 440 determines whether or not the operation state of the engine 10 is “a deceleration operation state in which fuel injection is stopped”. More specifically, the CPU determines whether or not the accelerator pedal operation amount Accp is “0” and the engine speed NE is equal to or higher than a threshold engine speed NEth. At this time, if the operation state of the engine 10 is not “decelerated operation state in which fuel injection is stopped”, the CPU makes a “No” determination at step 440 to proceed to step 470 to set the value of the supply control flag XNH3 to “0”. To "". Thereby, the urea water supply control for ammonia generation is completed.
- the CPU makes a “Yes” determination at step 440 to proceed to step 450 where the urea SCR catalyst bed temperature TempSCR is “ It is determined whether or not the control end threshold catalyst bed temperature TempSCReth is smaller than the threshold urea SCR catalyst bed temperature TempSCRsth.
- the control end threshold catalyst bed temperature TempSCReth is set to “the lowest temperature at which the urea SCR catalyst 44 can generate ammonia and reduce NOx”.
- the CPU makes a “No” determination at step 450 to proceed to step 470 to set the value of the supply control flag XNH3 to “0”. Set to. Thereby, the urea water supply control for ammonia generation is completed.
- the CPU makes a “Yes” determination at step 450 to proceed to step 460, where the acidic condensed water amount Sacidw is “threshold acidic condensation. It is determined whether or not the control end threshold value acidic condensate water amount Sacidweth is smaller than the water amount Sacidwsth. At this time, if the acidic condensate amount Sacidw is not greater than or equal to the control end threshold acidic condensate amount Sacidweth, the CPU makes a “No” determination at step 460 to proceed to step 470 to set the value of the supply control flag XNH3 to “0”. To do. Thereby, the urea water supply control for ammonia generation is completed.
- the CPU makes a “Yes” determination at step 460 to directly proceed to step 495 to end the present routine tentatively.
- the value of the supply control flag XNH3 is maintained at “1”. Therefore, the urea water supply control for ammonia generation is continued.
- Step 510 The CPU estimates the exhaust gas temperature TempEx based on the engine operation parameters (for example, the fuel injection amount Q and the engine speed NE). More specifically, the CPU applies the actual fuel injection amount Q and the actual engine rotation speed NE to the table MapTempEx that defines the relationship between the fuel injection amount Q and the engine rotation speed NE and the exhaust temperature TempEx. The actual exhaust temperature TempEx is estimated.
- the engine operation parameters for example, the fuel injection amount Q and the engine speed NE. More specifically, the CPU applies the actual fuel injection amount Q and the actual engine rotation speed NE to the table MapTempEx that defines the relationship between the fuel injection amount Q and the engine rotation speed NE and the exhaust temperature TempEx.
- the actual exhaust temperature TempEx is estimated.
- Step 520 The CPU estimates the urea SCR catalyst bed temperature TempSCR based on the following equation (5).
- the urea SCR catalyst bed temperature TempSCR (n + 1) on the left side of the equation (5) is the updated urea SCR catalyst bed temperature TempSCR, and the urea SCR catalyst bed temperature TempSCR (n) on the right side of the equation (5) is the urea before the update.
- the value ⁇ in the equation (5) is a constant larger than “0” and smaller than “1”.
- Step 530 The CPU estimates the slip catalyst bed temperature TempSLP based on the equation described in step 530, which is the same as the equation (5).
- the value ⁇ in the equation is a constant larger than “0” and smaller than the value ⁇ .
- the CPU may acquire the urea SCR catalyst bed temperature TempSCR based on the output value of the urea SCR catalyst bed temperature sensor.
- the CPU may acquire the slip catalyst bed temperature TempSLP based on the output value of the slip catalyst bed temperature sensor.
- the CPU executes the routine shown by the flowchart in FIG. 6 every time a predetermined time elapses. Therefore, when the predetermined timing comes, the CPU starts processing from step 600 in FIG. 6 and sequentially performs the processing from step 610 to step 650 described below.
- Step 610 The CPU reads the fuel injection amount Q (command value).
- Step 620 The CPU reads the actual low pressure EGR gas flow rate.
- Step 630 The CPU reads the actual total gas amount.
- Step 640 The CPU reads the actual cooling water temperature THW.
- Step 650 The CPU calculates the actual low pressure EGR rate ⁇ LP by dividing the actual low pressure EGR gas flow rate by the actual total gas amount.
- step 660 determines whether or not the value of the supply control flag XNH3 is “0”. At this time, if the value of the supply control flag XNH3 is “0”, the CPU makes a “Yes” determination at step 660 to perform the processing of step 670 and step 680 described below in order, and then proceeds to step 695. The routine is temporarily terminated.
- Step 670 The CPU calculates an increase amount ⁇ Sa of acidic condensed water according to the following equation (6).
- the basis of the above equation (6) is as follows.
- the rate at which water vapor condenses (becomes condensed water) in the low-pressure EGR passage including the low-pressure EGR cooler 62 and the intake passage including the intercooler 34 is proportional to the amount of heat taken by the steam in the “EGR passage and intake passage”.
- Step 680 The CPU estimates the amount of acidic condensed water Sacidw based on the following equation (7).
- the acidic condensed water amount Sacidw (n + 1) on the left side of the equation (7) is the updated acidic condensed water amount Sacidw
- the acidic condensed water amount Sacidw (n) on the right side of the equation (7) is the acidic condensed water amount Sacidw before the update.
- the CPU proceeds to step 695 to end the present routine tentatively. That is, the CPU obtains the acidic condensed water amount Sacidw by accumulating the increase amount ⁇ Sa of acidic condensed water.
- step 660 when the value of the supply control flag XNH3 is “1”, the urea water supply control for ammonia generation is executed, so that the acidic condensed water is gradually neutralized by ammonia. Therefore, when the value of the supply control flag XNH3 is “1” at the time when the CPU executes the process of step 660, the CPU determines “No” in step 660 and proceeds to step 690, where the amount of acidic condensed water A value obtained by subtracting a certain amount ⁇ A from Sacidw is acquired as a new acidic condensed water amount Sacidw. Thereafter, the CPU proceeds to step 695 to end the present routine tentatively. If the acidic condensed water amount Sacidw becomes a negative value as a result of the calculation, the acidic condensed water amount Sacidw is set to “0”.
- the first control device Fuel supply means (fuel injection valve 21) for supplying fuel to the internal combustion engine; A urea SCR catalyst 44 disposed in the exhaust passage of the engine; Urea water supply means (urea water addition valve 46) for supplying urea water to the urea SCR catalyst 44; Low pressure gas recirculation means (low pressure EGR system 60); Control means.
- the control means includes Controlling the amount of fuel supplied from the fuel supply means (fuel injection valve 21) to the engine based on a parameter representing the operating state of the engine 10 (step 210 and step 215 in FIG. 2);
- the opening degree of the low pressure EGR valve 63 is controlled based on a parameter representing the operating state of the engine 10 (step 225 and step 230 in FIG. 2), Based on the parameters representing the operating state of the engine 10 such that an amount of ammonia estimated to be necessary for reducing the nitrogen oxides contained in the exhaust gas is generated in the urea SCR catalyst 44.
- Nitrogen oxide reduction urea water supply control for controlling the amount of the urea water supplied from the water supply means is executed (step 245 in FIG. 2).
- control means includes The amount of acidic condensate generated by the gas passing through the low-pressure EGR passage (low-pressure EGR pipe 61) and accumulated in the low-pressure EGR passage and the intake passage is estimated based on a parameter representing the operating state of the engine (FIG. Routine 6), It is determined whether or not a specific condition including the condition that the estimated amount of acidic condensate is equal to or greater than the threshold amount of acid condensate (step 360 in FIG. 3) is satisfied (steps 340 to 360 in FIG. 3), When it is determined that the specific condition is satisfied, the gas flowing out from the urea SCR catalyst 44 passes through the low-pressure EGR passage and flows into the intake passage (steps 250 to 260 in FIG. 2).
- the amount of the urea water supplied from the urea water supply means so that ammonia flows out from the urea SCR catalyst 44 is “an amount larger than the amount required for the urea water supply control for nitrogen oxide reduction”
- the urea water supply control for ammonia generation set to "" is executed for a predetermined time (step 265 in FIG. 2 and routine in FIG. 4).
- the first control device can reduce the possibility of corrosion of engine components.
- control means includes When the condition that the engine 10 is in the deceleration operation state is further satisfied, it is determined that the specific condition is satisfied (step 340 in FIG. 3), and When the specific condition is satisfied, the supply of the fuel from the fuel supply means is stopped (see the determination of “Yes” in step 205 in FIG. 2), and the low-pressure EGR valve opening is set to “the specific It is changed to an opening on the opening side that is larger than the opening just before the condition is satisfied, for example, a fully opened opening (step 250 in FIG. 2).
- the low pressure EGR valve opening degree is large when the engine 10 is in the deceleration operation state and the fuel supply is stopped (when it is not necessary to consider the deterioration of combustion due to the gas passing through the low pressure EGR passage). Since the opening is set, a large amount of gas containing ammonia flowing out from the urea SCR catalyst 44 can be recirculated to the intake passage. As a result, acidic condensed water can be neutralized within a short time.
- the first control device includes an exhaust throttle valve 47 that is disposed at a position downstream of the connection position of the low-pressure EGR passage of the exhaust passage and changes the passage cross-sectional area of the exhaust passage.
- the control means sets the opening degree of the exhaust throttle valve 47 to “a closing side opening degree smaller than the opening degree immediately before the specific condition is satisfied, for example, a fully closed opening degree” when the specific condition is satisfied. Change (step 255 in FIG. 2).
- the first control device A turbine 43 disposed at a position upstream of the urea SCR catalyst 44 in the exhaust passage, and a compressor 35 rotated by the turbine 43 and disposed at a position downstream of the “connection position of the low pressure EGR passage in the intake passage”.
- a turbocharger including a provided compressor 35; A high-pressure EGR pipe 51 and a high-pressure EGR pipe 51 that constitute a high-pressure EGR passage that communicates a position upstream of the turbine 43 in the exhaust passage and a downstream position of the compressor 35 in the intake passage, and the high-pressure EGR passage
- High-pressure gas recirculation means (high-pressure EGR system 50) including a high-pressure EGR valve 52 whose opening is changed so as to change the passage cross-sectional area; Is provided.
- control means sets the opening degree of the high pressure EGR valve 52 to “a closing side opening degree smaller than the opening degree immediately before the specific condition is satisfied, for example, a fully closed opening degree” when the specific condition is satisfied.
- Change step 260 in FIG. 2.
- the first control device may continue the ammonia generation urea water supply control for a certain period of time as long as the engine 10 is in the decelerating operation state and the fuel supply is stopped.
- second control device a control device for an internal combustion engine according to a second embodiment of the present invention
- the second control device satisfies the specific condition described below. Then, urea water supply control for ammonia generation is executed.
- Condition 2-1 The flow rate of the gas passing through the low pressure EGR passage is not less than a predetermined threshold flow rate. Actually, the actual low pressure EGR rate is equal to or higher than the threshold low pressure EGR rate.
- Condition 2-2 The urea SCR catalyst bed temperature is equal to or higher than the threshold urea SCR catalyst bed temperature.
- Condition 2-3 The slip catalyst bed temperature is equal to or higher than the threshold slip catalyst bed temperature.
- Condition 2-4 The estimated acidic condensate amount is equal to or greater than a threshold acid condensate amount (ammonia generation urea water supply control start threshold).
- Condition 2-4 is an indispensable condition for satisfying the specific condition.
- Control execution> The CPU repeatedly executes the control execution routine shown in FIG. 7 every elapse of a predetermined time. Therefore, when the predetermined timing comes, the CPU starts the process from step 700 of FIG. 7 and executes the processes of steps 205 to 215 and steps 225 to 240. Thus, the fuel injection amount, the high pressure EGR valve opening, the low pressure EGR valve opening, and the exhaust throttle valve opening are controlled.
- step 710 determines whether or not the value of the supply control flag XNH3 is “0”. At this time, if the value of the supply control flag XNH3 is “0”, the CPU makes a “Yes” determination at step 710 to proceed to step 245 to execute the nitrogen oxide reduction urea water supply control. Proceed to to end the present routine.
- step 710 when the value of the supply control flag XNH3 is “1” at the time when the CPU executes the process of step 710, the CPU determines “No” in step 710 and proceeds to step 720 to generate ammonia. The urea water supply control is performed. At this time, the CPU sets the opening of the exhaust throttle valve 47 to an opening other than the fully closed opening.
- the CPU is an amount necessary for purifying (reducing) NOx in the exhaust gas in the urea SCR catalyst 44 based on the engine operating parameters (for example, the fuel injection amount Q and the engine rotational speed NE).
- the amount of urea water SureraNox that is estimated to be necessary and sufficient to generate the ammonia in the urea SCR catalyst 44 is determined.
- the CPU determines the amount of urea water SureraNH3 required for generating ammonia in the urea SCR catalyst 44 to neutralize the acidic condensate in the low pressure EGR passage and the intake passage based on the urea SCR catalyst bed temperature. .
- the amount SureaNH3 may be a constant value.
- the CPU may execute the urea water amount feedback control shown in FIG. Thereafter, the CPU proceeds to step 795 to end the present routine tentatively.
- ammonia flows into the low pressure gas passage and the intake passage together with the low pressure EGR gas. Therefore, acidic condensed water is neutralized.
- the CPU executes the “ammonia-generating urea water supply control / start determination routine” shown by the flowchart in FIG. 8 every time a predetermined time elapses. Therefore, when the predetermined timing comes, the CPU starts the process from step 800 of FIG. 8 and proceeds to step 805 to determine whether or not the value of the supply control flag XNH3 is “0”.
- step 805 the CPU makes a “Yes” determination at step 805 to sequentially perform the processing from step 810 to step 825 described below, and then proceeds to step 830.
- Step 810 The CPU reads the urea SCR catalyst bed temperature TempSCR estimated separately by the routine of FIG. Step 815: The CPU reads the slip catalyst bed temperature TempSLP estimated separately by the routine of FIG. Step 820: The CPU reads the acid condensed water amount Sacidw estimated separately by the routine of FIG. Step 825: The CPU reads the actual low pressure EGR rate ⁇ LP separately estimated by the routine of FIG.
- step 830 the CPU determines whether the urea SCR catalyst bed temperature TempSCR is equal to or higher than the threshold urea SCR catalyst bed temperature TempSCRsth (whether the above condition 2-2 is satisfied). At this time, if the urea SCR catalyst bed temperature TempSCR is not equal to or higher than the threshold urea SCR catalyst bed temperature TempSCRsth, the CPU makes a “No” determination at step 830 to directly proceed to step 895 to end the present routine tentatively. As a result, the value of the supply control flag XNH3 is maintained at “0”.
- the CPU makes a “Yes” determination at step 830 to proceed to step 835 where the slip catalyst bed temperature TempSLP is the threshold slip catalyst. It is determined whether or not the bed temperature is equal to or higher than TempSLPsth (that is, whether or not the condition 2-3 is satisfied).
- This threshold slip catalyst bed temperature TempSLPsth is set to a temperature equal to or higher than the temperature at which the slip catalyst 45 can sufficiently purify ammonia.
- the CPU makes a “No” determination at step 835 to directly proceed to step 895 to end the present routine tentatively.
- the value of the supply control flag XNH3 is maintained at “0”.
- the CPU makes a “Yes” determination at step 835 to proceed to step 840 where the actual low pressure EGR rate ⁇ LP becomes the threshold low pressure EGR rate ⁇ LPsth. It is determined whether or not this is the case (that is, whether or not the condition 2-1 is satisfied). At this time, if the actual low pressure EGR rate ⁇ LP is not equal to or greater than the threshold low pressure EGR rate ⁇ LPsth, the CPU makes a “No” determination at step 840 to directly proceed to step 895 to end the present routine tentatively. As a result, the value of the supply control flag XNH3 is maintained at “0”.
- step 840 the CPU makes a “Yes” determination at step 840 to proceed to step 845, where the acidic condensed water amount Sacidw is equal to or greater than the threshold acidic condensed water amount Sacidwsth. (That is, whether or not the condition 2-4 is satisfied).
- the CPU makes a “No” determination at step 845 to directly proceed to step 895 to end the present routine tentatively. As a result, the value of the supply control flag XNH3 is maintained at “0”.
- the CPU makes a “Yes” determination at step 845 to proceed to step 850 to set the value of the supply control flag XNH3 to “1”. . Thereafter, the CPU proceeds to step 895 to end the present routine tentatively.
- step 805 When the CPU proceeds again to step 805 in the state where the value of the supply control flag XNH3 is set to “1” in this way, the CPU determines “No” in step 805 and proceeds directly to step 895. This routine is temporarily terminated. As a result, the value of the supply control flag XNH3 is maintained at “1”.
- the CPU executes the “ammonia generation urea water supply control / start determination routine” shown in the flowchart of FIG. 9 every time a predetermined time elapses. Therefore, when the predetermined timing comes, the CPU starts the process from step 900 in FIG. 9 and proceeds to step 905 to determine whether or not the value of the supply control flag XNH3 is “1”. At this time, if the value of the supply control flag XNH3 is “0”, the CPU makes a “No” determination at step 905 to directly proceed to step 995 to end the present routine tentatively.
- step 905 the CPU makes a “Yes” determination at step 905, sequentially performs the processing from step 910 to step 925 described below, and proceeds to step 930.
- Step 910 The CPU reads the urea SCR catalyst bed temperature TempSCR estimated separately by the routine of FIG.
- Step 915 The CPU reads the slip catalyst bed temperature TempSLP estimated separately by the routine of FIG.
- Step 920 The CPU reads the acid condensed water amount Sacidw estimated separately by the routine of FIG.
- Step 925 The CPU reads the actual low pressure EGR rate ⁇ LP estimated separately by the routine of FIG.
- step 930 determines whether or not the urea SCR catalyst bed temperature TempSCR is equal to or higher than the control end threshold catalyst bed temperature TempSCReth. At this time, if the urea SCR catalyst bed temperature TempSCR is not equal to or higher than the control end threshold catalyst bed temperature TempSCReth, the CPU makes a “No” determination at step 930 to proceed to step 950 to set the value of the supply control flag XNH3 to “0”. Set. Thereby, the urea water supply control for ammonia generation is completed.
- the CPU makes a “Yes” determination at step 930 to proceed to step 935, where the slip catalyst bed temperature TempSLP is “threshold slip”. It is determined whether or not the control end threshold slip catalyst bed temperature TempSLPeth is smaller than the catalyst bed temperature TempSLPsth.
- the control end threshold slip catalyst bed temperature TempSLPeth is set to the lowest temperature at which the slip catalyst 45 can sufficiently purify ammonia.
- the CPU makes a “No” determination at step 935 to proceed to step 950 to set the value of the supply control flag XNH3 to “0”. Set. Thereby, the urea water supply control for ammonia generation is completed.
- step 935 the actual low pressure EGR rate ⁇ LP is “threshold low pressure”. It is determined whether or not the control end threshold low pressure EGR rate ⁇ LPeth, which is smaller than the EGR rate ⁇ LPsth by a predetermined value. At this time, if the actual low pressure EGR rate ⁇ LP is not equal to or greater than the control end threshold low pressure EGR rate ⁇ LPeth, the CPU makes a “No” determination at step 940 to proceed to step 950 to set the value of the supply control flag XNH3 to “0”. To do. Thereby, the urea water supply control for ammonia generation is completed.
- step 940 the CPU makes a “Yes” determination at step 940 to proceed to step 945 where the acidic condensate water amount Sacidw is the control end threshold acidic condensation. It is determined whether or not the amount of water is greater than Sacidweth. At this time, if the acidic condensate amount Sacidw is not greater than or equal to the control end threshold acidic condensate amount Sacidweth, the CPU makes a “No” determination at step 945 to proceed to step 950 to set the value of the supply control flag XNH3 to “0”. . Thereby, the urea water supply control for ammonia generation is completed.
- the CPU makes a “Yes” determination at step 945 to directly proceed to step 995 to end the present routine tentatively.
- the value of the supply control flag XNH3 is maintained at “1”.
- the CPU may execute feedback control of the urea water amount when executing the processing of step 720 in FIG.
- the CPU executes the urea water amount feedback control
- the CPU proceeds to step 720 in FIG. 7, the CPU starts processing from step 1000 in FIG. 10, and sequentially performs processing from step 1005 to step 1030 described below.
- Step 1005 The CPU calculates the urea water amount (urea water amount) SureaNox based on the engine operation parameters (for example, the fuel injection amount Q, the engine rotational speed NE, and the urea SCR catalyst bed temperature TempSCR).
- the urea water amount SureaNox is the amount of urea water to be supplied to the urea SCR catalyst 44 in order to reduce NOx in the exhaust gas.
- the electric control device 90 stores a table that defines the relationship between the engine operation parameter and the urea water amount SureraNox, and by applying the current engine operation parameter to the table, the current urea water amount SureaNox. Is calculated.
- Step 1010 The CPU calculates the amount of urea water (urea water amount) SureaNH3 based on the urea SCR catalyst bed temperature TempSCR.
- the urea water amount SureaNH3 is the amount of urea water necessary to generate ammonia in the urea SCR catalyst 44 for neutralizing acidic condensed water in the low pressure EGR passage and the intake passage.
- the electric control device 90 stores a table that defines the relationship between the urea SCR catalyst bed temperature TempSCR and the urea water amount SureaNH3, and by applying the current urea SCR catalyst bed temperature TempSCR to the table, The urea water amount SureaNH3 at the present time is calculated.
- the urea water amount SureaNH3 may be a constant value.
- Step 1015 The CPU reads the output value DNOx of the NOx sensor 76.
- Step 1020 The CPU reads the actual low pressure EGR rate ⁇ LP calculated separately (see step 650 in FIG. 6).
- Step 1025 The CPU reads the total gas amount Gall.
- Step 1030 The CPU estimates the amount of ammonia (slip catalyst inflow ammonia amount) SSNH3 flowing into the slip catalyst 45 based on the following equation (8).
- the threshold ammonia amount SLNH3th is an ammonia amount that the slip catalyst 45 can purify.
- the threshold ammonia amount SLNH3th may be a constant value, or may be a value determined so as to increase as the slip catalyst bed temperature TempSLP increases.
- the CPU makes a “Yes” determination at step 1035 to proceed to step 1040 to decrease the correction coefficient kh by a fixed amount ⁇ kh.
- the correction coefficient kh is limited to a value larger than zero.
- the correction coefficient kh is set to “1” in the above-described initial routine.
- step 1045 determines the final urea water supply amount SU by multiplying the correction coefficient kh by “the sum of the urea water amount SureaNox and the urea water amount SureraNH3”.
- a supply amount SU of urea water is supplied to the urea SCR catalyst 44. Then, the CPU proceeds to step 795 in FIG.
- the slip catalyst inflow ammonia amount SSNH3 is less than the threshold ammonia amount SLNH3th at the time when the CPU executes the process of step 1035, the possibility that ammonia will pass through the slip catalyst 45 is low, and more ammonia is urea. While being generated by the SCR catalyst 44, the ammonia can flow into the low pressure EGR passage and the intake passage. If the slip catalyst inflow ammonia amount SSNH3 is less than the threshold ammonia amount SLNH3th, the CPU makes a “No” determination at step 1035 to proceed to step 1050 to increase the correction coefficient kh by a fixed amount ⁇ kh.
- step 1045 the CPU executes the process of step 1045 to determine the final urea water supply amount SU, and supplies the urea water of the urea water supply amount SU from the urea water addition valve 46 to the urea SCR catalyst 44. Then, the CPU proceeds to step 795 in FIG.
- the second control device executes the urea water supply control for nitrogen oxide reduction (see step 245 in FIG. 7), and the estimated amount of acidic condensed water is the threshold acidic condensed water amount.
- the routine of FIG. 8, particularly step 845 the gas flowing out from the urea SCR catalyst 44 passes through the low pressure EGR passage and flows into the intake passage. (That is, during the execution of the low pressure EGR gas recirculation control, Step 225 to Step 240 in FIG. 7) “Urea water supplied from the urea water supply means so that ammonia flows out from the urea SCR catalyst 44.
- the amount of water is set to a larger amount (SureaNOx + SureaNH3) than the “SureaNOx required for controlling the supply of urea water for nitrogen oxide reduction”. (See step 720 in FIG. 7).
- control means of the second control device is: When the fuel is supplied from the fuel supply means to the engine, the low-pressure EGR that has flowed out of the urea SCR catalyst 44 by changing the opening of the low-pressure EGR valve based on a parameter that represents the operating state of the engine. It is configured to execute low pressure EGR gas recirculation control for flowing gas into the intake passage (see step 225, step 230, and step 240 in FIG. 7), and When the condition that the flow rate of the gas passing through the low pressure EGR passage is equal to or higher than a predetermined threshold flow rate during the low pressure EGR gas recirculation control is further established (“Yes” in step 840 of FIG. 8) Refer to the determination.), It is configured to determine that the specific condition is satisfied.
- the second control device generates ammonia when the flow rate of the gas passing through the low pressure EGR passage is equal to or greater than a predetermined threshold flow rate (when the actual low pressure EGR rate ⁇ LP is equal to or greater than the threshold low pressure EGR rate ⁇ LPsth). Since the urea water supply control is performed, most of the gas containing ammonia flowing out from the urea SCR catalyst 44 can be returned to the intake passage through the low pressure EGR passage without flowing into the slip catalyst 45. Therefore, it is possible to neutralize acidic condensed water without wasting urea water wastefully.
- control means includes urea SCR catalyst bed temperature estimation means (step 520 in FIG. 5), and the condition that the estimated urea SCR catalyst bed temperature is equal to or higher than the threshold urea SCR catalyst bed temperature is further established. In this case, it is determined that the specific condition is satisfied (see determination of “Yes” in step 830 in FIG. 8).
- the urea water supply control for ammonia generation is executed, so that it is possible to avoid wasteful consumption of the urea water.
- control means includes Slip catalyst bed temperature estimating means for estimating the slip catalyst bed temperature TempSLP based on a parameter representing the operating state of the engine (step 530 in FIG. 5);
- the condition that the estimated slip catalyst bed temperature is equal to or higher than the threshold slip catalyst bed temperature is further satisfied, it is determined that the specific condition is satisfied (determination of “Yes” in step 835 in FIG. 8). See), and
- the opening of the exhaust throttle valve is set to an opening other than the fully closed opening (see Step 240 and Step 720 in FIG. 7).
- a control device for an internal combustion engine according to a third embodiment of the present invention (hereinafter also simply referred to as “third control device”) will be described.
- the third control device stops the fuel supply when the condition that the amount of acidic condensate is equal to or greater than the threshold amount of acid condensate when a request to stop the operation of the engine 10 (engine operation stop request) occurs. Then, the engine 10 is forcibly rotated by external power, and the urea water supply control for ammonia generation is executed.
- the third control device performs the first control in that the CPU of the electric control device 90 executes the routine of FIG. 11 instead of FIG. 2, the routine of FIG. 12 instead of FIG. 3, and the routine of FIG. It is different from the device. Therefore, this difference will be mainly described below. Note that steps for performing the same processing as the steps already described in FIGS. 11 to 13 are denoted by the same reference numerals as those given to such steps. Detailed description of these steps will be omitted as appropriate.
- the CPU repeatedly executes the control execution routine shown in FIG. 11 every elapse of a predetermined time. Therefore, when the predetermined timing comes, the CPU starts the processing from step 1100 in FIG. 11, and in step 1110, based on a signal from an ignition key switch (not shown), a “request to stop the operation of the engine 10 at this time ( It is determined whether or not an engine operation stop request has occurred. At this time, if an engine operation stop request has not occurred, the CPU makes a “Yes” determination at step 1110 to execute the processes of steps 205 to 215 and steps 225 to 245.
- step 1195 “fuel injection amount control, low-pressure EGR gas recirculation control, high-pressure EGR gas recirculation control, nitrogen oxide reduction urea water supply control”, and the like are performed during normal operation. Thereafter, the CPU proceeds to step 1195 to end the present routine tentatively.
- step 1110 if an engine operation stop request is generated at the time when the CPU executes the process of step 1110, the CPU makes a “No” determination at step 1110 to proceed to step 1120 and supply control flag XNH3. It is determined whether or not the value of “1” is “1”.
- step 1120 makes a “No” determination at step 1120 to directly proceed to step 1195 to end the present routine tentatively. As a result, the fuel supply is stopped, and the operation of the engine 10 is stopped.
- the value of the supply control flag XNH3 indicates that the urea SCR catalyst bed temperature TempSCR is equal to or higher than the threshold urea SCR catalyst bed temperature TempSCRsth and the amount of acidic condensed water Sacidw when an engine operation stop request is generated. Is equal to or greater than the threshold acidic condensed water amount Sacidwsth (that is, when a specific condition is satisfied), it is set to “1”.
- Step 1130 The CPU forcibly rotates the engine 10 by the motoring device (starter in this example) 22. That is, the motoring of the engine 10 is executed. In this case, since the process of step 215 is not executed, no fuel is supplied to the engine 10.
- Step 250 The CPU sends an instruction signal to the low pressure EGR valve actuator 63a so that the low pressure EGR valve 63 is fully opened (or the opening degree on the opening side).
- Step 255 The CPU sends an instruction signal to the exhaust throttle valve actuator 47a so that the exhaust throttle valve 47 is in a fully closed state (or the opening on the closing side).
- Step 260 The CPU sends an instruction signal to the high pressure EGR valve actuator 52a so that the high pressure EGR valve 52 is in a fully closed state (or the opening on the closing side).
- Step 265 The CPU supplies a predetermined amount of urea water from the urea water addition valve 46. That is, the CPU executes urea water supply control for ammonia generation. At this time, the CPU may change the predetermined amount so that the predetermined amount increases as the urea SCR catalyst bed temperature separately estimated by a routine described later increases.
- the engine 10 is forcibly rotated and the engine 10 discharges air.
- urea water is supplied to the urea SCR catalyst 44, a gas containing ammonia flows out from the urea SCR catalyst 44. Further, the gas containing ammonia flows into the intake passage through the low pressure EGR passage. As a result, the acidic condensed water is neutralized.
- the CPU executes the “ammonia-generating urea water supply control / start determination routine” shown by the flowchart in FIG. 12 every time a predetermined time elapses. Accordingly, when the predetermined timing comes, the CPU starts the process from step 1200 in FIG. 12 and proceeds to step 1210 to determine whether or not the value of the supply control flag XNH3 is “0”.
- the CPU makes a “Yes” determination at step 1210 to proceed to step 1220.
- “whether or not the current time point is immediately after the engine operation stop request is generated is determined. Is determined.
- the CPU makes a “No” determination at step 1220 to directly proceed to step 1295 to end the present routine tentatively.
- the value of the supply control flag XNH3 is maintained at “0”.
- step 1220 makes a “Yes” determination at step 1220 to execute the processing of step 320, step 330, and step 350 to step 370. (See FIG. 3). Therefore, when the urea SCR catalyst bed temperature TempSCR is equal to or higher than the threshold urea SCR catalyst bed temperature TempSCRsth and the acidic condensate water amount Sacidw is equal to or higher than the threshold acid condensate water amount Sacidwsth, the value of the supply control flag XNH3 is set to “1”. Is done. At this time, as described above, the engine 10 is forcibly rotated and the urea water supply control for ammonia generation is executed.
- step 1210 when the CPU proceeds again to step 1210 in a state where the value of the supply control flag XNH3 is set to “1”, the CPU makes a “No” determination at step 1210 to directly proceed to step 1295 to execute this routine. Is temporarily terminated. As a result, the value of the supply control flag XNH3 is maintained at “1”.
- the urea SCR catalyst bed temperature TempSCR is equal to or higher than the threshold urea SCR catalyst bed temperature TempSCRsth. If not, and if the acidic condensed water amount Sacidw is not equal to or greater than the threshold acidic condensed water amount Sacidwsth, the CPU proceeds to step 1295 without executing the processing of step 370. Therefore, the value of the supply control flag XNH3 is maintained at “0”.
- the CPU executes the “ammonia generation urea water supply control / end determination routine” shown in the flowchart of FIG. 13 every time a predetermined time elapses.
- the routine shown in FIG. 13 is the same as the routine in which step 440 of the routine of FIG. 4 is omitted.
- the CPU proceeds to step 470 and sets the value of the supply control flag XNH3 to “0”. Thereby, the urea water supply control for ammonia generation is completed. Further, the motoring for forcibly rotating the engine 10 is also completed (see “No” in step 1120 in FIG. 11 and step 1130). Note that the CPU may execute the motoring of the engine 10 and the urea water supply control for ammonia generation for a certain period from the time when the value of the supply control flag XNH3 is changed from “0” to “1”.
- the third control device executes the nitrogen oxide reduction urea water supply control (see step 245 in FIG. 11), and the estimated amount of acidic condensed water is the threshold acidic condensed water amount.
- the specific condition including the above condition is satisfied (the routine of FIG. 12, particularly step 360)
- the gas flowing out from the urea SCR catalyst 44 passes through the low pressure EGR passage and flows into the intake passage. 11 (step 1130, step 250 to step 260 in FIG. 11), the amount of the urea water supplied from the urea water supply means so that ammonia flows out from the urea SCR catalyst 44 is reduced for the nitrogen oxide reduction.
- Control means is provided for executing urea water supply control for generating ammonia for a predetermined time, which is set to an amount larger than the amount required for urea water supply control (FIG. Referring to the first step 265.).
- control means of the third control device is: Including an engine operation stop request generation determination means (step 1220 in FIG. 12 and step 1110 in FIG. 11) for determining whether or not an engine operation stop request for stopping the operation of the engine has occurred.
- an engine operation stop request generation determination means for determining whether or not an engine operation stop request for stopping the operation of the engine has occurred.
- the engine operation stop request is generated, the supply of the fuel from the fuel supply means is stopped (refer to the determination of “No” in step 1110 of FIG. 11 and the processing after the determination).
- the engine operation stop request it is determined that the specific condition is satisfied when the condition that the estimated acidic condensed water amount is equal to or larger than the threshold acidic condensed water amount is satisfied (FIG. 12). See steps 1220 and 360 of FIG.
- a motor that forcibly rotates the engine 10 with external power from the time when the specific condition is satisfied until the estimated amount of acidic condensate becomes smaller than the motoring stop threshold (see step 460 and step 470 in FIG. 13).
- Ring means (steps 1120 and 1130 in FIG. 11) are provided.
- the acid condensed water can be neutralized after the engine shutdown request is generated.
- the control means according to the modified example of the third control device supplies the fuel so that the engine 10 is idled from the time when the specific condition is satisfied until the estimated amount of acidic condensate is smaller than the engine stop threshold.
- the low pressure EGR cooler 62 disposed in the low pressure EGR passage has a bypass passage, an appropriate amount of low pressure EGR gas is passed through the bypass passage, and the intercooler 34 disposed in the intake passage is bypassed.
- a passage is provided, an appropriate amount of gas is passed through the bypass passage. According to this, since excessive EGR gas does not flow into the engine, the idling operation can be stably continued.
- control means of the modified example of the third control device is Including an engine operation stop request occurrence determining means for determining whether an engine operation stop request for stopping operation of the engine has occurred, It is determined that the specific condition is satisfied when the condition that the estimated acidic condensed water amount is equal to or greater than the threshold acidic condensed water amount when the engine operation stop request is generated; and The engine is continuously operated by continuously supplying fuel from the fuel supply means to the engine until the estimated acidic condensate amount becomes smaller than an engine stop threshold value from the time when the specific condition is satisfied. Also good.
- control means of the third control device and its modification examples are: Urea SCR catalyst bed temperature estimating means (step 520 in FIG. 5) for estimating the urea SCR catalyst bed temperature, which is the bed temperature of the urea SCR catalyst, based on a parameter representing the operating state of the engine;
- Urea SCR catalyst bed temperature estimating means for estimating the urea SCR catalyst bed temperature, which is the bed temperature of the urea SCR catalyst, based on a parameter representing the operating state of the engine.
- the urea water supply control for ammonia generation is not executed, so that it is possible to avoid wasteful consumption of the urea water.
- a control device for an internal combustion engine according to a fourth embodiment of the present invention (hereinafter simply referred to as “fourth control device”) will be described.
- the ammonia generation urea water supply control is executed, so that ammonia remains in the low pressure EGR passage and the intake passage at the end of the ammonia generation urea water supply control. .
- ammonia is released into the atmosphere.
- the fourth control device determines whether or not “ammonia generated by the urea water supply control for ammonia generation” remains in the intake passage when the engine operation stop request is generated, and the ammonia enters the intake passage.
- the operation of the engine is continued by continuously supplying fuel to the engine until “the ammonia in the intake passage is removed (scavenging)”. That is, the ammonia removal control is executed for a predetermined time. Since the gas in the low pressure EGR passage flows into the intake passage, if no ammonia remains in the intake passage, no ammonia remains in the low pressure EGR passage.
- the fourth control device executes a routine executed by the CPU of the first or second control device. Furthermore, the CPU of the fourth control device repeatedly executes each of the routines shown in FIGS. 14 to 16 every elapse of a predetermined time. Therefore, when the predetermined timing comes, the CPU starts the process from step 1400 in FIG. 14 and proceeds to step 1410 to determine that the engine stop request has been issued based on a signal from an ignition key switch (not shown). It is determined whether or not it is immediately after. At this time, if not immediately after the engine operation stop request is generated, the CPU makes a “No” determination at step 1410 to set the value of the operation continuation flag XIDL to “0”. The value of the operation continuation flag XIDL is set to “0” in the above-described initial routine. Thereafter, the CPU proceeds to step 1495 to end the present routine tentatively.
- the CPU makes a “Yes” determination at step 1410, proceeds to step 1430, and is “calculated separately by the routine shown in FIG.
- the intake passage scavenging amount SINsoki is read.
- the CPU proceeds to step 1440 to determine whether or not the intake passage scavenging amount SINsoki is equal to or less than the intake passage volume (including the gas passage volumes of the intercooler 34 and the compressor 35) VolIN.
- the CPU makes a “No” determination at step 1440 to proceed to step 1495 via step 1420. As a result, the operation of the engine 10 is stopped.
- step 1440 the intake passage scavenging amount SINsoki is less than or equal to the intake passage volume VolIN when the CPU executes the processing of step 1440, “ammonia generated by the ammonia generation urea water supply control” remains in the intake passage. it seems to do. Therefore, in this case, the CPU makes a “Yes” determination at step 1440 to proceed to step 1450 to continue the engine operation (idle operation). That is, for example, the CPU executes steps 210 and 215 and steps 225 to 245 in FIG.
- step 1460 the CPU proceeds to step 1460 to set the value of the operation continuation flag XIDL to “1”. Thereafter, the CPU proceeds to step 1495 to end the present routine tentatively.
- step 1510 the CPU makes a “Yes” determination at step 1510 to proceed to step 1520, and “calculated separately by the routine shown in FIG.
- the intake passage scavenging amount SINsoki is read.
- step 1530 determines whether or not the intake passage scavenging amount SINsoki is greater than or equal to the intake passage volume VolIN.
- the CPU makes a “No” determination at step 1530 to directly proceed to step 1595 to end the present routine tentatively.
- the value of the operation continuation flag XIDL is maintained at “1”, and the idle operation is continued.
- step 1530 when the CPU executes the process of step 1530, if the intake passage scavenging amount SINsoki is greater than or equal to the intake passage volume VolIN, “ammonia generated by the ammonia generation urea water supply control” remains in the intake passage. It is not considered. Therefore, the CPU makes a “Yes” determination at step 1530 to proceed to step 1540 to stop the fuel injection (fuel supply) to the engine 10 to stop the operation of the engine 10. Thereafter, the CPU proceeds to step 1595 to end the present routine tentatively. As a result, the ammonia removal control ends.
- ⁇ Calculation of scavenging amount of low pressure EGR passage> When the predetermined timing is reached, the CPU starts processing from step 1600 in FIG. 16, and proceeds to step 1610 to determine whether or not the value of the supply control flag XNH3 is “0”. At this time, if the value of the supply control flag XNH3 is “1”, the urea water supply control for ammonia generation is executed, and therefore the gas containing ammonia passes through the “low pressure EGR passage and the intake passage”. Yes. In other words, the scavenging amount SLEsoki of the low pressure EGR passage is “0”.
- the CPU makes a “No” determination at step 1610 to proceed to step 1620 to set the scavenging amount SLEsoki of the low pressure EGR passage to “0”.
- the CPU proceeds to step 1630 to set the value of the calculation execution flag XST to “0”.
- the value of the calculation execution flag XST is set to “0” in the above-described initial routine. As will be described later, when the value of the calculation execution flag XST is changed from “0” to “1”, calculation of the intake passage scavenging amount SINsoki is started.
- the CPU makes a “Yes” determination at step 1610 to proceed to step 1640 to read the low-pressure EGR passage passing gas amount (low-pressure EGR gas flow rate) GLPEGR.
- step 1650 the CPU proceeds to step 1650 to calculate the scavenging amount of the low pressure EGR passage (low pressure EGR passage scavenging amount) SLEsoki based on the following equation (9).
- the low-pressure EGR passage scavenging amount SLEsoki (n + 1) on the left side of the equation (9) is the updated low-pressure EGR passage scavenging amount SLEsoki
- the low-pressure EGR passage scavenging amount SLEsoki (n) on the right side of the equation (9) is the low pressure before the update. This is the EGR passage scavenging amount SLEsoki.
- step 1660 the CPU proceeds to step 1660 to determine whether or not the low pressure EGR passage scavenging amount SLEsoki is equal to or greater than the volume of the low pressure EGR passage (including the gas passage volume of the low pressure EGR cooler 62) VOLLPEGR. At this time, if the low pressure EGR passage scavenging amount SLEsoki is not greater than or equal to the low pressure EGR passage volume VOLLPEGR, the CPU makes a “No” determination at step 1660 to proceed to step 1695 via step 1630.
- step 1660 the CPU makes a “Yes” determination at step 1660 to proceed to step 1670 to set the value of the calculation execution flag XST to “1”. Then, the process proceeds to step 1695 to end this routine once.
- step 1710 determines whether or not the value of the calculation execution flag XST is “1”. At this time, if the value of the calculation execution flag XST is “0”, the CPU makes a “No” determination at step 1710 to proceed to step 1720 to set the value of the intake passage scavenging amount SINsoki to “0”.
- the CPU makes a “Yes” determination at step 1710 to proceed to step 1730 to proceed to the low pressure EGR passage. Read the passing gas amount GLPEGR. Next, in step 1740, the CPU reads “fresh air flow rate Ga measured by air flow meter 71”.
- step 1750 the CPU proceeds to step 1750 to calculate the intake passage scavenging amount (intake passage scavenging amount) SINsoki based on the following equation (10).
- the intake passage scavenging amount SINsoki (n + 1) on the left side of the equation (10) is the updated intake passage scavenging amount SINsoki
- the intake passage scavenging amount SINsoki (n) on the right side of the equation (10) is the intake passage scavenging amount before the update. It is SINsoki.
- the fourth control device is Engine operation stop request generation determining means (step 1410 in FIG. 14) for determining whether or not an engine operation stop request for stopping the operation of the engine 10 has occurred;
- an ammonia residual determination means for determining whether or not ammonia generated by the ammonia generation urea water supply control remains in the intake passage (see FIG. 14 steps 1440),
- the ammonia residual determination means determines whether or not ammonia generated by the ammonia generation urea water supply control remains in the intake passage (see FIG. 14 steps 1440), the urea water is supplied to the urea water.
- ammonia removal control for continuing to supply fuel from the fuel supply means to the engine is executed for a predetermined time (step 1450 in FIG. 14, step 1530 in FIG. 15 and (See step 1540.)
- the operation of the engine 10 is stopped when ammonia does not remain in the low pressure EGR passage and the intake passage. Therefore, it is possible to avoid the release of ammonia into the atmosphere when performing repair / inspection.
- the fourth control device A first gas amount (scavenging amount SLEsoki in the low pressure EGR passage) that is an integrated amount of gas that has passed through the low pressure EGR passage after the stop of the ammonia generation urea water supply control is estimated (routine in FIG. 16). It is determined whether or not the estimated first gas amount is equal to or greater than the volume of the low pressure EGR passage (step 1660 in FIG. 16), and further, the estimated first gas amount is equal to or greater than the volume of the low pressure EGR passage.
- the ammonia residual determination means includes It is determined that the ammonia remains in the intake passage when the estimated second gas amount (intake passage scavenging amount SINsoki) is not equal to or larger than the intake passage volume when the engine operation stop request is generated. (Refer to the determination of “Yes” in step 1440 in FIG. 14).
- the fourth control device When the estimated second gas amount (intake passage scavenging amount SINsoki) exceeds the intake passage volume, the ammonia removal control is stopped to stop the operation of the engine (step 1530 in FIG. 15). And step 1540). Thereby, it is possible to avoid the operation of the engine 10 being continued in vain.
- each control device neutralizes the acidic condensed water generated and staying in the low pressure EGR passage and the intake passage with the ammonia generated by the urea SCR catalyst 44. Can do. Therefore, since the engine component parts are not easily corroded by acidic condensed water, the durability of the engine 10 can be enhanced.
- this invention is not limited to the said embodiment, A various modification can be employ
- the engine 10 to which the present invention is applied may not include the high pressure EGR system.
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Abstract
Description
前記尿素水供給手段は、前記尿素SCR触媒に尿素水を供給する。
低圧EGR管は、前記排気通路の前記尿素SCR触媒の下流位置と前記機関の吸気通路とを連通する低圧EGR通路を構成する。
低圧EGR弁は、前記低圧EGR管に介装されるとともに、前記低圧EGR通路の通路断面積を変更するように開度が変更される。
前記制御手段は、前記機関の運転状態を表すパラメータに基いて前記低圧EGR弁の開度を制御する。
前記制御手段は、「前記排ガスに含まれる窒素酸化物を還元するのに必要であると推定される量のアンモニア」が前記尿素SCR触媒内にて生成されるように、前記機関の運転状態を表すパラメータに基いて「前記尿素水供給手段から供給される前記尿素水の量を制御する窒素酸化物還元用尿素水供給制御」を実行する。
(1)「前記低圧EGR通路を通過するガスにより生成され且つ同低圧EGR通路及び前記吸気通路に蓄積される酸性凝縮水」の量(酸性凝縮水量)を前記機関の運転状態を表すパラメータに基いて推定し、
(2)前記推定された酸性凝縮水の量が閾値酸性凝縮水量以上であるという条件を含む特定条件が成立したか否かを判定し、
(3)その特定条件が成立したと判定したとき、前記尿素SCR触媒から流出したガスが前記低圧EGR通路を通過して前記吸気通路へと流入している状態にて同尿素SCR触媒からアンモニアが流出するように、「前記尿素水供給手段から供給されるべき前記尿素水の量」を「前記窒素酸化物還元用尿素水供給制御のために必要とされる量」よりも多い量に設定する制御(アンモニア生成用尿素水供給制御)を所定時間実行する。
なお、前記アンモニア生成用尿素水供給制御を実行する前記所定時間は、同制御の開始から一定時間が経過するまでであってもよく、同制御の開始時点から前記推定された酸性凝縮水の量が「閾値酸性凝縮水量から所定値だけ小さい値」以下になる時点までの時間であってもよい。
前記機関が減速運転状態にあるときという条件が更に成立しているときに前記特定条件が成立すると判定し、且つ、
前記特定条件が成立したとき、前記燃料供給手段からの前記燃料の供給を停止するとともに前記低圧EGR弁開度を前記特定条件が成立する直前の開度よりも大きい所定の開度に変更するように構成される。
前記排気通路の前記低圧EGR通路の接続位置よりも下流の位置に配設されるとともに同排気通路の通路断面積を変更する排気絞り弁を備え、
前記制御手段は、
前記特定条件が成立したとき前記排気絞り弁の開度を前記特定条件が成立する直前の開度よりも小さい所定の開度に変更するように構成される。
前記過給機は、前記排気通路の前記尿素SCR触媒よりも上流の位置に配設されたタービンと、そのタービンにより回転させられるコンプレッサであって前記吸気通路の前記低圧EGR通路の接続位置よりも下流の位置に配設されたコンプレッサとを含む。
前記高圧ガス還流手段は、前記排気通路の前記タービンよりも上流の位置と前記吸気通路の前記コンプレッサよりも下流の位置とを連通する高圧EGR通路を構成する高圧EGR管、及び、その高圧EGR管に介装されるとともに前記高圧EGR通路の通路断面積を変更するように開度が変更される高圧EGR弁、を含む。
そして、前記制御手段は、前記特定条件が成立したとき前記高圧EGR弁の開度を前記特定条件が成立する直前の開度よりも小さい所定の開度に変更するように構成される。
前記尿素SCR触媒の床温である尿素SCR触媒床温を前記機関の運転状態を表すパラメータに基いて推定する尿素SCR触媒床温推定手段を含み、且つ、
前記推定された尿素SCR触媒床温が閾値尿素SCR触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成される。
前記制御手段は、
前記燃料供給手段から前記燃料が前記機関に供給されている場合に前記機関の運転状態を表すパラメータに基いて前記低圧EGR弁の開度を変更することにより前記尿素SCR触媒から流出した低圧EGRガスを前記吸気通路へと流入させる低圧EGRガス再循環制御を実行するように構成される。
前記低圧EGRガス再循環制御中において前記低圧EGR通路を通過するガスの流量が所定の閾値流量以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成される。
なお、前記低圧EGR通路を通過するガスの流量が所定の閾値流量以上であるという条件は、低圧EGR率が閾値低圧EGR率以上であるという条件と同義である。即ち、制御手段は、特定条件が成立しているか否かを判定する際、低圧EGR通路を通過するガスの流量が閾値流量以上であるか否かを判定してもよく、代替として、低圧EGR率が閾値低圧EGR率以上であるか否かを判定してもよい。
前記尿素SCR触媒の床温である尿素SCR触媒床温を前記機関の運転状態を表すパラメータに基いて推定する尿素SCR触媒床温推定手段を含み、且つ、
前記推定された尿素SCR触媒床温が閾値尿素SCR触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成される。
前記排気通路の前記低圧EGR通路の接続位置よりも下流の位置に配設されるとともにアンモニアを浄化するスリップ触媒と、
前記排気通路の前記低圧EGR通路の接続位置よりも下流の位置であり且つ前記スリップ触媒よりも上流の位置に配設されるとともに同排気通路の通路断面積を変更する排気絞り弁と、
を備えることができる。
前記スリップ触媒の床温であるスリップ触媒床温を前記機関の運転状態を表すパラメータに基いて推定するスリップ触媒床温推定手段を含み、
前記推定されたスリップ触媒床温が閾値スリップ触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定し、且つ、
前記特定条件が成立したとき前記排気絞り弁の開度を全閉開度以外の開度に設定するように構成されることが好ましい。
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段を含み、
前記機関運転停止要求が発生したとき前記燃料供給手段からの前記燃料の供給を停止し、且つ、
前記機関運転停止要求が発生した場合に前記推定された酸性凝縮水量が前記閾値酸性凝縮水量以上であるという条件が成立しているときに前記特定条件が成立すると判定するように構成される。
前記特定条件が成立した時点から前記推定された酸性凝縮水量がモータリング停止閾値より小さくなるまで前記機関を外部動力により強制的に回転させるモータリング手段を備える。
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段を含み、
前記機関運転停止要求が発生した場合に前記推定された酸性凝縮水量が前記閾値酸性凝縮水量以上であるという条件が成立しているときに前記特定条件が成立すると判定するように構成される。
前記特定条件が成立した時点から前記推定された酸性凝縮水量が機関停止閾値より小さくなるまで前記燃料供給手段から前記機関に燃料を供給させ続けることにより前記機関の運転を継続するように構成される。
前記尿素SCR触媒の床温である尿素SCR触媒床温を前記機関の運転状態を表すパラメータに基いて推定する尿素SCR触媒床温推定手段を含み、且つ、
前記推定された尿素SCR触媒床温が閾値尿素SCR触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成される。
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段と、
前記機関の運転を停止する機関運転停止要求が発生したとき前記アンモニア生成用尿素水供給制御により生成されたアンモニアが前記吸気通路に残留しているか否かを判定するアンモニア残留判定手段と、
を備える。
前記アンモニア残留判定手段により前記吸気通路に前記アンモニアが残留していると判定された場合に前記尿素水を前記尿素水供給手段から供給させない状態にて前記機関の運転を継続するように前記燃料供給手段から同機関に燃料を供給させ続けるアンモニア除去制御を所定時間実行するように構成される。
前記掃気状態推定手段は、
(1)前記アンモニア生成用尿素水供給制御の実行停止後から前記低圧EGR通路を通過したガスの積算量である第1ガス量を推定するとともに、
(2)前記推定された第1ガス量が前記低圧EGR通路の容積以上となったか否かを判定し、更に、
(3)前記推定された第1ガス量が前記低圧EGR通路の容積以上となった時点から前記吸気通路を通過するガスの積算量である第2ガス量を推定する。
前記機関運転停止要求が発生したときに前記推定されている前記第2ガス量が前記吸気通路の容積以上でない場合に前記吸気通路に前記アンモニアが残留していると判定するように構成される。
前記推定されている前記第2ガス量が前記吸気通路の容積以上となったときに前記アンモニア除去制御を停止して前記機関の運転を停止するように構成される。
(構成)
図1は、本発明の第1実施形態に係る内燃機関の制御装置(以下、単に「第1制御装置」とも称呼する。)が適用される内燃機関10の概略構成を示している。機関10は、直列4気筒ディーゼル機関である。機関10は、エンジン本体20、吸気系統30、排気系統40、高圧EGRシステム50及び低圧EGRシステム60を備えている。更に、第1制御装置は電気制御装置90を含んでいる。
吸気管32は吸気マニホールド31の集合部31bに接続されている。
吸気マニホールド31及び吸気管32等は吸気通路を構成している。
コンプレッサ35は、吸気管32のインタークーラー34よりも上流の位置に配設されている。コンプレッサ35は後述するタービン43とともに回転し、吸気管32を流れるガスを圧縮するようになっている。
排気管42は排気マニホールド41の集合部41bに接続されている。
排気マニホールド41及び排気管42等は排気通路を構成している。
吸気圧センサ72は、吸気管32の高圧スロットル弁33の下流位置におけるガスの圧力を検出し、過給圧を表す信号Pを発生するようになっている。
冷却水温センサ74は、機関10の冷却水の温度(冷却水温)を検出し、冷却水温を表す信号THWを発生するようになっている。
機関回転速度センサ75は、内燃機関10の回転速度を検出し、機関回転速度NEを表す信号を発生するようになっている。
低圧EGR弁上流圧力センサ78は、低圧EGR管61の「低圧EGR弁63よりも上流の位置」におけるガスの圧力(低圧EGR弁上流圧)を検出し、低圧EGR弁上流圧を表す信号Puを発生するようになっている。
低圧EGRガス温度センサ79は、低圧EGR管61の「低圧EGR弁63よりも上流の位置」におけるガスの温度(低圧EGR弁上流温度)を検出し、低圧EGR弁上流温度を表す信号Tuを発生するようになっている。
次に、上記のように構成された第1制御装置の作動の概要について説明する。第1制御装置のCPUは、アクセル操作量を表す信号Accp及び機関回転速度NEに基づいて燃料噴射量を決定し、その決定した燃料噴射量が各燃焼室に噴射される(供給される)ように、燃料噴射弁21に指示信号を送出する。但し、CPUは、機関10の運転状態を表すパラメータである機関運転パラメータ(例えば、アクセルペダル操作量Accp及び機関回転速度NE)に基いて機関10の運転状態が減速運転状態にあると判定されるとき、燃料の噴射を停止する(燃料供給を停止する。)。
CPUは、通常運転時において、機関運転パラメータ(例えば、燃料噴射量Q及び機関回転速度NE)に基いて目標低圧EGR率を決定し、その目標低圧EGR率が実現されるように低圧EGR弁アクチュエータ63aに指示信号を送出する。
CPUは、通常運転時において、機関運転パラメータ(例えば、燃料噴射量Q及び機関回転速度NE)に基いて目標排気絞り弁開度を決定し、その目標排気弁絞り開度が実現されるように排気絞り弁アクチュエータ47aに指示信号を送出する。
(条件1-2)尿素SCR触媒床温が閾値尿素SCR触媒床温以上である。
(条件1-3)推定された酸性凝縮水量が閾値酸性凝縮水量(アンモニア生成用尿素水供給制御開始閾値)以上である。なお、条件1-3は、前記特定条件が成立するための必須条件である。
次に、第1制御装置の実際の作動について説明する。
<制御実行>
電気制御装置90のCPUは、図2に示した制御実行ルーチンを所定時間の経過毎に繰り返し実行するようになっている。従って、所定のタイミングになると、CPUは図2のステップ200から処理を開始し、ステップ205にて機関10が減速運転状態にあるか否かを判定する。より具体的には、CPUは、アクセルペダル操作量Accpが「0」であり且つ機関回転速度NEが閾値機関回転速度NEth以上であるとき、機関10が減速運転状態にあると判定する。
ステップ230:CPUは、実際の低圧EGR率(実低圧EGR率)が目標低圧EGR率に一致するように低圧EGR弁アクチュエータ63aに指示信号を送出し、低圧EGR弁63の開度を制御する。
ステップ255:CPUは、排気絞り弁47が「供給制御フラグXNH3の値が「0」から「1」へと変化する直前の開度(前記特定条件が成立する直前の開度)よりも小さい所定の開度(閉じ側の開度であり、本例においては全閉状態)」になるように排気絞り弁アクチュエータ47aに指示信号を送出する。
ステップ260:CPUは、高圧EGR弁52が「供給制御フラグXNH3の値が「0」から「1」へと変化する直前の開度(前記特定条件が成立する直前の開度)よりも小さい所定の開度(閉じ側の開度であり、本例においては全閉状態)」になるように高圧EGR弁アクチュエータ52aに指示信号を送出する。
CPUは、所定時間が経過する毎に図3にフローチャートにより示した「アンモニア生成用尿素水供給制御・開始判定ルーチン」を実行するようになっている。従って、所定のタイミングになると、CPUは図3のステップ300から処理を開始してステップ310に進み、供給制御フラグXNH3の値が「0」であるか否かを判定する。
CPUは、所定時間が経過する毎に図4にフローチャートにより示した「アンモニア生成用尿素水供給制御・終了判定ルーチン」を実行するようになっている。従って、所定のタイミングになると、CPUは図4のステップ400から処理を開始してステップ410に進み、供給制御フラグXNH3の値が「1」であるか否かを判定する。このとき、供給制御フラグXNH3の値が「0」であると、CPUはステップ410にて「No」と判定し、ステップ495に直接進んで本ルーチンを一旦終了する。
なお、制御終了閾値触媒床温TempSCRethは、尿素SCR触媒44が「アンモニアを生成でき且つNOxを還元できる最低温度」に設定されている。このとき、尿素SCR触媒床温TempSCRが制御終了閾値触媒床温TempSCReth以上でなければ、CPUはステップ450にて「No」と判定してステップ470に進み、供給制御フラグXNH3の値を「0」に設定する。これにより、アンモニア生成用尿素水供給制御が終了する。
CPUは、所定時間が経過する毎に図5にフローチャートにより示したルーチンを実行するようになっている。従って、所定のタイミングになると、CPUは図5のステップ500から処理を開始し、以下に述べるステップ510乃至ステップ530の処理を順に行い、ステップ595に進んで本ルーチンを一旦終了する。
CPUは、所定時間が経過する毎に図6にフローチャートにより示したルーチンを実行するようになっている。従って、所定のタイミングになると、CPUは図6のステップ600から処理を開始し、以下に述べるステップ610乃至ステップ650の処理を順に行う。
ステップ620:CPUは実際の低圧EGRガス流量を読み込む。
ステップ630:CPUは実際の全ガス量を読み込む。
ステップ640:CPUは実際の冷却水温THWを読み込む。
ステップ650:CPUは、実際の低圧EGRガス流量を実際の全ガス量にて除することによって、実際の低圧EGR率γLPを算出する。
単位時間当たりに機関10から排気通路へと排出される水蒸気量W1は燃料噴射量Qに比例する。即ち、W1=k1・Qである。
単位時間当たりに低圧EGR通路を通過して吸気通路へと流入する水蒸気量W2は、水蒸気量W1と実際の低圧EGR率γLPとの積に比例する。即ち、W2=k2・W1・γLP=k1・k2・Q・γLPである。
低圧EGRクーラー62を含む低圧EGR通路及びインタークーラー34を含む吸気通路にて水蒸気が凝結する(凝縮水になる)割合は、その水蒸気が「EGR通路及び吸気通路」にて奪われる熱量に比例し、その熱量は冷却水温THWに実質的に比例する。即ち、単位時間あたりに生成される凝縮水の量W3=k3・THW・W2=k1・k2・k3・THW・Q・γLPである。
ここで、凝縮水が酸性凝縮水となるので、k1・k2・k3=kとおくと、上記(6)式が得られる。
内燃機関に燃料を供給する燃料供給手段(燃料噴射弁21)と、
前記機関の排気通路に配設される尿素SCR触媒44と、
前記尿素SCR触媒44に尿素水を供給する尿素水供給手段(尿素水添加弁46)と、
低圧ガス還流手段(低圧EGRシステム60)と、
制御手段と、を含む。
前記機関10の運転状態を表すパラメータに基いて前記燃料供給手段(燃料噴射弁21)から同機関に供給される燃料の量を制御し(図2のステップ210及びステップ215)、
前記機関10の運転状態を表すパラメータに基いて前記低圧EGR弁63の開度を制御し(図2のステップ225及びステップ230)、
前記排ガスに含まれる窒素酸化物を還元するのに必要であると推定される量のアンモニアが尿素SCR触媒44内にて生成されるように前記機関10の運転状態を表すパラメータに基いて前記尿素水供給手段から供給される前記尿素水の量を制御する窒素酸化物還元用尿素水供給制御を実行する(図2のステップ245)。
前記低圧EGR通路(低圧EGR管61)を通過するガスにより生成され且つ同低圧EGR通路及び吸気通路に蓄積される酸性凝縮水の量を前記機関の運転状態を表すパラメータに基いて推定し(図6のルーチン)、
前記推定された酸性凝縮水の量が閾値酸性凝縮水量以上であるという条件(図3のステップ360)を含む特定条件が成立したか否かを判定し(図3のステップ340乃至ステップ360)、
前記特定条件が成立したと判定したとき、尿素SCR触媒44から流出したガスが前記低圧EGR通路を通過して前記吸気通路へと流入している状態にて(図2のステップ250乃至ステップ260)、尿素SCR触媒44からアンモニアが流出するように前記尿素水供給手段から供給される前記尿素水の量を「前記窒素酸化物還元用尿素水供給制御のために必要とされる量よりも多い量」に設定するアンモニア生成用尿素水供給制御を所定時間実行する(図2のステップ265及び図4のルーチン)。
機関10が減速運転状態にあるときという条件が更に成立しているときに前記特定条件が成立すると判定し(図3のステップ340)、且つ、
前記特定条件が成立したとき、前記燃料供給手段からの前記燃料の供給を停止するとともに(図2のステップ205での「Yes」との判定を参照。)、低圧EGR弁開度を「前記特定条件が成立する直前の開度よりも大きい開き側の開度、例えば、全開開度」に変更する(図2のステップ250)。
排気通路の尿素SCR触媒44よりも上流の位置に配設されたタービン43と、タービン43により回転させられるコンプレッサ35であって「吸気通路の低圧EGR通路の接続位置」よりも下流の位置に配設されたコンプレッサ35とを含む過給機と、
前記排気通路のタービン43よりも上流の位置と前記吸気通路のコンプレッサ35の下流位置とを連通する高圧EGR通路を構成する高圧EGR管51及び高圧EGR管51に介装されるとともに高圧EGR通路の通路断面積を変更するように開度が変更される高圧EGR弁52を含む高圧ガス還流手段(高圧EGRシステム50)と、
を備える。
次に、本発明の第2実施形態に係る内燃機関の制御装置(以下、単に「第2制御装置」とも称呼する。)について説明する。第2制御装置は、燃料噴射が実行され且つ低圧EGRシステムを用いた低圧EGRガス再循環制御及び窒素酸化物還元用尿素水供給制御が実行されている場合に、以下に述べる特定条件が成立すると、アンモニア生成用尿素水供給制御を実行する。
(条件2-2)尿素SCR触媒床温が閾値尿素SCR触媒床温以上である。
(条件2-3)スリップ触媒床温が閾値スリップ触媒床温以上である。
(条件2-4)推定された酸性凝縮水量が閾値酸性凝縮水量(アンモニア生成用尿素水供給制御開始閾値)以上である。なお、条件2-4は、前記特定条件が成立するための必須条件である。
第2制御装置は、電気制御装置90のCPUが、図2に代わる図7のルーチン、図3に代わる図8のルーチン、及び、図4に代わる「図9及び図10」のルーチンを実行する点において第1制御装置と相違している。従って、以下、この相違点を中心に説明する。なお、図7において図2に示したステップと同一の処理を行うためのステップには、図2のそのようなステップに付された符号と同一の符号が付されている。これらのステップについての詳細な説明は適宜省略される。
CPUは所定時間の経過毎に図7に示した制御実行ルーチンを繰り返し実行するようになっている。従って、所定のタイミングになると、CPUは図7のステップ700から処理を開始し、ステップ205乃至ステップ215、並びに、ステップ225乃至ステップ240の処理を実行する。これにより、燃料噴射量、高圧EGR弁開度、低圧EGR弁開度、及び、排気絞り弁開度が制御される。
CPUは、所定時間が経過する毎に図8にフローチャートにより示した「アンモニア生成用尿素水供給制御・開始判定ルーチン」を実行するようになっている。従って、所定のタイミングになると、CPUは図8のステップ800から処理を開始してステップ805に進み、供給制御フラグXNH3の値が「0」であるか否かを判定する。
ステップ815:CPUは、図5のルーチンにより別途推定されているスリップ触媒床温TempSLPを読み込む。
ステップ820:CPUは、図6のルーチンにより別途推定されている酸性凝縮水量Sacidwを読み込む。
ステップ825:CPUは、図6のルーチンにより別途推定されている実低圧EGR率γLPを読み込む。
CPUは、所定時間が経過する毎に図9にフローチャートにより示した「アンモニア生成用尿素水供給制御・開始判定ルーチン」を実行するようになっている。従って、所定のタイミングになると、CPUは図9のステップ900から処理を開始してステップ905に進み、供給制御フラグXNH3の値が「1」であるか否かを判定する。このとき、供給制御フラグXNH3の値が「0」であると、CPUはステップ905にて「No」と判定し、ステップ995に直接進んで本ルーチンを一旦終了する。
ステップ915:CPUは、図5のルーチンにより別途推定されているスリップ触媒床温TempSLPを読み込む。
ステップ920:CPUは、図6のルーチンにより別途推定されている酸性凝縮水量Sacidwを読み込む。
ステップ925:CPUは、図6のルーチンにより別途推定されている実低圧EGR率γLPを読み込む。
CPUは、図7のステップ720の処理を実行する際、尿素水量のフィードバック制御を実行してもよい。CPUが尿素水量のフィードバック制御を実行する場合、CPUは図7のステップ720に進んだとき、図10のステップ1000から処理を開始し、以下に述べるステップ1005乃至ステップ1030の処理を順に行う。
ステップ1020:CPUは、別途算出されている実低圧EGR率γLPを読み込む(図6のステップ650を参照。)。
ステップ1025:CPUは、全ガス量Gallを読み込む。
アンモニア生成用尿素水供給制御中において、尿素SCR触媒44には「排ガス中のNOxを還元するために尿素SCR触媒44に供給すべき量(尿素水量SureaNox)の尿素水」以上の量(=SureaNox+SureaNH3)の尿素水が供給されている。従って、尿素SCR触媒44からNOxは流出しないと考えられる。よって、NOxセンサ76の出力値DNOxは「尿素SCR触媒44から流出するガスのアンモニア濃度」のみに比例した値となる。一方、スリップ触媒45に流入するガスの総量は、全ガス量Gallと値(1-γLP)との積である。よって、(8)式の右辺は、スリップ触媒流入アンモニア量SSNH3である。
前記燃料供給手段から前記燃料が前記機関に供給されている場合に前記機関の運転状態を表すパラメータに基いて前記低圧EGR弁の開度を変更することにより前記尿素SCR触媒44から流出した低圧EGRガスを前記吸気通路へと流入させる低圧EGRガス再循環制御を実行するように構成され(図7のステップ225、ステップ230及びステップ240を参照。)、且つ、
前記低圧EGRガス再循環制御中において前記低圧EGR通路を通過するガスの流量が所定の閾値流量以上であるという条件が更に成立しているときに(図8のステップ840での「Yes」との判定を参照。)、前記特定条件が成立すると判定するように構成されている。
スリップ触媒床温TempSLPを機関の運転状態を表すパラメータに基いて推定するスリップ触媒床温推定手段を含み(図5のステップ530)、
前記推定されたスリップ触媒床温が閾値スリップ触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定し(図8のステップ835での「Yes」との判定を参照。)、且つ、
前記特定条件が成立したとき前記排気絞り弁の開度を全閉開度以外の開度に設定するように構成されている(図7のステップ240及びステップ720を参照。)。
次に、本発明の第3実施形態に係る内燃機関の制御装置(以下、単に「第3制御装置」とも称呼する。)について説明する。第3制御装置は、機関10の運転を停止する要求(機関運転停止要求)が発生した場合に酸性凝縮水量が前記閾値酸性凝縮水量以上であるという条件が成立しているとき、燃料供給を停止し、機関10を外部動力によって強制的に回転させ、且つ、アンモニア生成用尿素水供給制御を実行する。
第3制御装置は、電気制御装置90のCPUが、図2に代わる図11のルーチン、図3に代わる図12のルーチン、及び、図4に代わる図13のルーチンを実行する点において第1制御装置と相違している。従って、以下、この相違点を中心に説明する。なお、図11乃至図13において既に説明したステップと同一の処理を行うためのステップには、そのようなステップに付された符号と同一の符号が付されている。これらのステップについての詳細な説明は適宜省略される。
CPUは所定時間の経過毎に図11に示した制御実行ルーチンを繰り返し実行するようになっている。従って、所定のタイミングになると、CPUは図11のステップ1100から処理を開始し、ステップ1110にて図示しないイグニッション・キー・スイッチからの信号に基いて「現時点において機関10の運転を停止する要求(機関運転停止要求)が発生しているか否か」を判定する。このとき、機関運転停止要求が発生していなければ、CPUはステップ1110にて「Yes」と判定し、ステップ205乃至ステップ215、並びに、ステップ225乃至ステップ245の処理を実行する。これにより、通常運転中における「燃料噴射量制御、低圧EGRガス再循環制御、高圧EGRガス再循環制御、及び、窒素酸化物還元用尿素水供給制御」等が実行される。その後、CPUはステップ1195に進み、本ルーチンを一旦終了する。
この場合、ステップ215の処理は実行されないので、機関10には燃料は供給されていない。
ステップ250:CPUは、低圧EGR弁63が全開状態(又は、前記開き側の開度)になるように低圧EGR弁アクチュエータ63aに指示信号を送出する。
ステップ255:CPUは、排気絞り弁47が全閉状態(又は、前記閉じ側の開度)になるように排気絞り弁アクチュエータ47aに指示信号を送出する。
ステップ260:CPUは、高圧EGR弁52が全閉状態(又は、前記閉じ側の開度)になるように高圧EGR弁アクチュエータ52aに指示信号を送出する。
CPUは、所定時間が経過する毎に図12にフローチャートにより示した「アンモニア生成用尿素水供給制御・開始判定ルーチン」を実行するようになっている。従って、所定のタイミングになると、CPUは図12のステップ1200から処理を開始してステップ1210に進み、供給制御フラグXNH3の値が「0」であるか否かを判定する。
CPUは、所定時間が経過する毎に図13にフローチャートにより示した「アンモニア生成用尿素水供給制御・終了判定ルーチン」を実行するようになっている。この図13に示したルーチンは、図4のルーチンのステップ440を省略したルーチンと同じである。
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段(図12のステップ1220及び図11のステップ1110)を含み、
前記機関運転停止要求が発生したとき前記燃料供給手段からの前記燃料の供給を停止し(図11のステップ1110での「No」との判定及びその判定以降の処理を参照。)、
前記機関運転停止要求が発生した場合に前記推定された酸性凝縮水量が前記閾値酸性凝縮水量以上であるという条件が成立しているときに前記特定条件が成立すると判定するように構成され(図12のステップ1220及びステップ360を参照。)、
更に、
前記特定条件が成立した時点から前記推定された酸性凝縮水量がモータリング停止閾値より小さくなるまで(図13のステップ460及びステップ470を参照。)、機関10を外部動力により強制的に回転させるモータリング手段(図11のステップ1120及びステップ1130)を備える。
第3制御装置の変形例に係る制御手段は、前記特定条件が成立した時点から前記推定された酸性凝縮水量が機関停止閾値より小さくなる時点まで、機関10をアイドル運転させるように前記燃料の供給を継続し、且つ、低圧EGR通路に配設された低圧EGRクーラー62がバイパス通路を有する場合そのバイパス通路に適量の低圧EGRガスを通過させ、且つ、吸気通路に配設されたインタークーラー34がバイパス通路を有する場合そのバイパス通路に適量のガスを通過させる。これによれば、過剰のEGRガスが機関に流入しないので、アイドル運転を安定的に継続することができる。
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段を含み、
前記機関運転停止要求が発生した場合に前記推定された酸性凝縮水量が前記閾値酸性凝縮水量以上であるという条件が成立しているときに前記特定条件が成立すると判定し、且つ、
前記特定条件が成立した時点から前記推定された酸性凝縮水量が機関停止閾値より小さくなるまで前記燃料供給手段から前記機関に燃料を供給させ続けることにより前記機関の運転を継続するように構成されてもよい。
前記尿素SCR触媒の床温である尿素SCR触媒床温を前記機関の運転状態を表すパラメータに基いて推定する尿素SCR触媒床温推定手段(図5のステップ520)を含み、且つ、
前記推定された尿素SCR触媒床温が閾値尿素SCR触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成されている(図12のステップ350)。
次に、本発明の第4実施形態に係る内燃機関の制御装置(以下、単に「第4制御装置」とも称呼する。)について説明する。第1及び第2制御装置によれば、アンモニア生成用尿素水供給制御が実行されるので、そのアンモニア生成用尿素水供給制御の終了時点においては低圧EGR通路及び吸気通路にアンモニアが残存している。この状態にて機関10の運転が停止され、修理・点検等のために低圧EGRシステムの構成部品及び吸気系部品が取り外されると、アンモニアが大気中に放出される。
<アンモニア除去制御(掃気制御)開始判定>
第4制御装置は、第1又は第2制御装置のCPUが実行するルーチンを実行する。更に、第4制御装置のCPUは、図14乃至図16に示されたルーチンのそれぞれを、所定時間の経過毎に繰り返し実行するようになっている。従って、所定のタイミングになると、CPUは図14のステップ1400から処理を開始し、ステップ1410に進んで図示しないイグニッション・キー・スイッチからの信号に基いて「現時点が、機関運転停止要求が発生した直後であるか否か」を判定する。このとき、機関運転停止要求が発生した直後でなければ、CPUはステップ1410にて「No」と判定し、運転継続フラグXIDLの値を「0」に設定する。なお、運転継続フラグXIDLの値は上述したイニシャルルーチンにおいて「0」に設定されるようになっている。その後、CPUはステップ1495に進んで本ルーチンを一旦終了する。
所定のタイミングになると、CPUは図15のステップ1500から処理を開始し、ステップ1510に進んで運転継続フラグXIDLの値が「1」であるか否かを判定する。このとき、運転継続フラグXIDLの値が「0」であると、CPUはステップ1595に直接進んで本ルーチンを一旦終了する。
所定のタイミングになると、CPUは図16のステップ1600から処理を開始し、ステップ1610に進んで供給制御フラグXNH3の値が「0」であるか否かを判定する。このとき、供給制御フラグXNH3の値が「1」であると、アンモニア生成用尿素水供給制御が実行されており、それ故、アンモニアを含むガスが「低圧EGR通路及び吸気通路」を通過している。換言すると、低圧EGR通路の掃気量SLEsokiは「0」である。
所定のタイミングになると、CPUは図17のステップ1700から処理を開始し、ステップ1710に進んで計算実行フラグXSTの値が「1」であるか否かを判定する。このとき、計算実行フラグXSTの値が「0」であると、CPUはステップ1710にて「No」と判定してステップ1720に進み、吸気通路掃気量SINsokiの値を「0」に設定する。
機関10の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段(図14のステップ1410)と、
前記機関の運転を停止する機関運転停止要求が発生したとき「前記アンモニア生成用尿素水供給制御により生成されたアンモニアが前記吸気通路に残留しているか否か」を判定するアンモニア残留判定手段(図14のステップ1440)と、
を備え、更に、
前記アンモニア残留判定手段により前記吸気通路に前記アンモニアが残留していると判定された場合に(図14のステップ1440での「Yes」との判定を参照。)、前記尿素水を前記尿素水供給手段から供給させない状態にて前記機関の運転を継続するように前記燃料供給手段から同機関に燃料を供給させ続けるアンモニア除去制御を所定時間実行する(図14のステップ1450、図15のステップ1530及びステップ1540を参照。)。
前記アンモニア生成用尿素水供給制御の実行停止後から前記低圧EGR通路を通過したガスの積算量である第1ガス量(低圧EGR通路の掃気量SLEsoki)を推定するとともに(図16のルーチン)、前記推定された第1ガス量が前記低圧EGR通路の容積以上となったか否かを判定し(図16のステップ1660)、更に、前記推定された第1ガス量が前記低圧EGR通路の容積以上となった時点から前記吸気通路を通過するガスの積算量である第2ガス量(吸気通路掃気量SINsoki)を推定する掃気状態推定手段を備え(図16のステップ1660及びステップ1670、並びに、図17のルーチン)、
前記アンモニア残留判定手段は、
前記機関運転停止要求が発生したときに前記推定されている前記第2ガス量(吸気通路掃気量SINsoki)が前記吸気通路の容積以上でない場合に前記吸気通路に前記アンモニアが残留していると判定する(図14のステップ1440での「Yes」との判定を参照。)。
前記推定されている前記第2ガス量(吸気通路掃気量SINsoki)が前記吸気通路の容積以上となったときに前記アンモニア除去制御を停止して前記機関の運転を停止する(図15のステップ1530及びステップ1540)。これにより、機関10の運転が無駄に継続されることを回避することができる。
Claims (14)
- 内燃機関に燃料を供給する燃料供給手段と、
前記機関の排気通路に配設される尿素SCR触媒であって同尿素SCR触媒に供給される尿素水から生成されるアンモニアによって同機関から排出された排ガスに含まれる窒素酸化物を還元することにより同窒素酸化物を浄化する尿素SCR触媒と、
前記尿素SCR触媒に尿素水を供給する尿素水供給手段と、
前記排気通路の前記尿素SCR触媒の下流位置と前記機関の吸気通路とを連通する低圧EGR通路を構成する低圧EGR管及び同低圧EGR管に介装されるとともに同低圧EGR通路の通路断面積を変更するように開度が変更される低圧EGR弁を含む低圧ガス還流手段と、
前記機関の運転状態を表すパラメータに基いて前記燃料供給手段から前記機関に供給される燃料の量を制御し、前記機関の運転状態を表すパラメータに基いて前記低圧EGR弁の開度を制御し、前記排ガスに含まれる窒素酸化物を還元するのに必要であると推定される量のアンモニアが前記尿素SCR触媒内にて生成されるように前記機関の運転状態を表すパラメータに基いて前記尿素水供給手段から供給される前記尿素水の量を制御する窒素酸化物還元用尿素水供給制御を実行する制御手段と、
を備えた内燃機関の制御装置において、
前記制御手段は、
前記低圧EGR通路を通過するガスにより生成され且つ同低圧EGR通路及び前記吸気通路に蓄積される酸性凝縮水の量を前記機関の運転状態を表すパラメータに基いて推定し、前記推定された酸性凝縮水の量が閾値酸性凝縮水量以上であるという条件を含む特定条件が成立したか否かを判定し、前記特定条件が成立したと判定したとき、前記尿素SCR触媒から流出したガスが前記低圧EGR通路を通過して前記吸気通路へと流入している状態にて同尿素SCR触媒からアンモニアが流出するように前記尿素水供給手段から供給される前記尿素水の量を前記窒素酸化物還元用尿素水供給制御のために必要とされる量よりも多い量に設定するアンモニア生成用尿素水供給制御を所定時間実行するように構成された制御装置。 - 請求項1に記載の内燃機関の制御装置において、
前記制御手段は、
前記機関が減速運転状態にあるときという条件が更に成立しているときに前記特定条件が成立すると判定し、且つ、
前記特定条件が成立したとき、前記燃料供給手段からの前記燃料の供給を停止するとともに前記低圧EGR弁開度を前記特定条件が成立する直前の開度よりも大きい所定の開度に変更するように構成された制御装置。 - 請求項2に記載の内燃機関の制御装置であって、
前記排気通路の前記低圧EGR通路の接続位置よりも下流の位置に配設されるとともに同排気通路の通路断面積を変更する排気絞り弁を備え、
前記制御手段は、
前記特定条件が成立したとき前記排気絞り弁の開度を前記特定条件が成立する直前の開度よりも小さい所定の開度に変更するように構成された制御装置。 - 請求項2又は請求項3に記載の内燃機関の制御装置であって、
前記排気通路の前記尿素SCR触媒よりも上流の位置に配設されたタービンと同タービンにより回転させられるコンプレッサであって前記吸気通路の前記低圧EGR通路の接続位置よりも下流の位置に配設されたコンプレッサとを含む過給機と、
前記排気通路の前記タービンよりも上流の位置と前記吸気通路の前記コンプレッサよりも下流の位置とを連通する高圧EGR通路を構成する高圧EGR管及び同高圧EGR管に介装されるとともに同高圧EGR通路の通路断面積を変更するように開度が変更される高圧EGR弁を含む高圧ガス還流手段と、
を備え、
前記制御手段は、
前記特定条件が成立したとき前記高圧EGR弁の開度を前記特定条件が成立する直前の開度よりも小さい所定の開度に変更するように構成された制御装置。 - 請求項1乃至請求項4の何れか一項に記載の内燃機関の制御装置において、
前記制御手段は、
前記尿素SCR触媒の床温である尿素SCR触媒床温を前記機関の運転状態を表すパラメータに基いて推定する尿素SCR触媒床温推定手段を含み、且つ、
前記推定された尿素SCR触媒床温が閾値尿素SCR触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成された制御装置。 - 請求項1に記載の内燃機関の制御装置において、
前記制御手段は、
前記燃料供給手段から前記燃料が前記機関に供給されている場合に前記機関の運転状態を表すパラメータに基いて前記低圧EGR弁の開度を変更することにより前記尿素SCR触媒から流出した低圧EGRガスを前記吸気通路へと流入させる低圧EGRガス再循環制御を実行するように構成され、且つ、
前記低圧EGRガス再循環制御中において前記低圧EGR通路を通過するガスの流量が所定の閾値流量以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成された制御装置。 - 請求項6に記載の内燃機関の制御装置において、
前記制御手段は、
前記尿素SCR触媒の床温である尿素SCR触媒床温を前記機関の運転状態を表すパラメータに基いて推定する尿素SCR触媒床温推定手段を含み、且つ、
前記推定された尿素SCR触媒床温が閾値尿素SCR触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成された制御装置。 - 請求項7に記載の内燃機関の制御装置であって、
前記排気通路の前記低圧EGR通路の接続位置よりも下流の位置に配設されるとともにアンモニアを浄化するスリップ触媒と、
前記排気通路の前記低圧EGR通路の接続位置よりも下流の位置であり且つ前記スリップ触媒よりも上流の位置に配設されるとともに同排気通路の通路断面積を変更する排気絞り弁と、
を備え、
前記制御手段は、
前記スリップ触媒の床温であるスリップ触媒床温を前記機関の運転状態を表すパラメータに基いて推定するスリップ触媒床温推定手段を含み、
前記推定されたスリップ触媒床温が閾値スリップ触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定し、且つ、
前記特定条件が成立したとき前記排気絞り弁の開度を全閉開度以外の開度に設定するように構成された制御装置。 - 請求項1に記載の内燃機関の制御装置において、
前記制御手段は、
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段を含み、
前記機関運転停止要求が発生したとき前記燃料供給手段からの前記燃料の供給を停止し、且つ、
前記機関運転停止要求が発生した場合に前記推定された酸性凝縮水量が前記閾値酸性凝縮水量以上であるという条件が成立しているときに前記特定条件が成立すると判定するように構成され、
更に、
前記特定条件が成立した時点から前記推定された酸性凝縮水量がモータリング停止閾値より小さくなるまで前記機関を外部動力により強制的に回転させるモータリング手段を備えた制御装置。 - 請求項1に記載の内燃機関の制御装置であって、
前記制御手段は、
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段を含み、
前記機関運転停止要求が発生した場合に前記推定された酸性凝縮水量が前記閾値酸性凝縮水量以上であるという条件が成立しているときに前記特定条件が成立すると判定し、且つ、
前記特定条件が成立した時点から前記推定された酸性凝縮水量が機関停止閾値より小さくなるまで前記燃料供給手段から前記機関に燃料を供給させ続けることにより前記機関の運転を継続するように構成された制御装置。 - 請求項9又は請求項10に記載の内燃機関の制御装置であって、
前記制御手段は、
前記尿素SCR触媒の床温である尿素SCR触媒床温を前記機関の運転状態を表すパラメータに基いて推定する尿素SCR触媒床温推定手段を含み、且つ、
前記推定された尿素SCR触媒床温が閾値尿素SCR触媒床温以上であるという条件が更に成立しているときに前記特定条件が成立すると判定するように構成された制御装置。 - 請求項1に記載の内燃機関の制御装置において、
前記制御手段は、
前記機関の運転を停止する機関運転停止要求が発生したか否かを判定する機関運転停止要求発生判定手段と、
前記機関の運転を停止する機関運転停止要求が発生したとき、前記アンモニア生成用尿素水供給制御により生成されたアンモニアが前記吸気通路に残留しているか否か、を判定するアンモニア残留判定手段と、
を備え、更に、
前記アンモニア残留判定手段により前記吸気通路に前記アンモニアが残留していると判定された場合に前記尿素水を前記尿素水供給手段から供給させない状態にて前記機関の運転を継続するように前記燃料供給手段から同機関に燃料を供給させ続けるアンモニア除去制御を所定時間実行するように構成された制御装置。 - 請求項12に記載の内燃機関の制御装置であって、
前記制御手段は、
前記アンモニア生成用尿素水供給制御の実行停止後から前記低圧EGR通路を通過したガスの積算量である第1ガス量を推定するとともに、前記推定された第1ガス量が前記低圧EGR通路の容積以上となったか否かを判定し、更に、前記推定された第1ガス量が前記低圧EGR通路の容積以上となった時点から前記吸気通路を通過するガスの積算量である第2ガス量を推定する掃気状態推定手段を備え、
前記アンモニア残留判定手段は、
前記機関運転停止要求が発生したときに前記推定されている前記第2ガス量が前記吸気通路の容積以上でない場合に前記吸気通路に前記アンモニアが残留していると判定するように構成された制御装置。 - 請求項13に記載の内燃機関の制御装置であって、
前記制御手段は、
前記推定されている前記第2ガス量が前記吸気通路の容積以上となったときに前記アンモニア除去制御を停止して前記機関の運転を停止するように構成された制御装置。
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JP2011548452A JP5170324B2 (ja) | 2011-06-02 | 2011-06-02 | 内燃機関の制御装置 |
CN201180017486.4A CN102918238B (zh) | 2011-06-02 | 2011-06-02 | 内燃机的控制装置 |
US14/004,065 US9494066B2 (en) | 2011-06-02 | 2011-06-02 | Control apparatus for an internal combustion engine |
PCT/JP2011/062672 WO2012164713A1 (ja) | 2011-06-02 | 2011-06-02 | 内燃機関の制御装置 |
EP11866592.6A EP2716892B1 (en) | 2011-06-02 | 2011-06-02 | Internal combustion engine control apparatus |
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JPWO2012164713A1 (ja) | 2014-07-31 |
EP2716892A1 (en) | 2014-04-09 |
JP5170324B2 (ja) | 2013-03-27 |
CN102918238A (zh) | 2013-02-06 |
EP2716892A4 (en) | 2015-03-11 |
EP2716892B1 (en) | 2016-11-30 |
US9494066B2 (en) | 2016-11-15 |
CN102918238B (zh) | 2015-09-02 |
US20140130483A1 (en) | 2014-05-15 |
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