WO2009101728A1 - 酸化触媒の故障診断装置及び酸化触媒の故障診断方法、並びに内燃機関の排気浄化装置 - Google Patents
酸化触媒の故障診断装置及び酸化触媒の故障診断方法、並びに内燃機関の排気浄化装置 Download PDFInfo
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- WO2009101728A1 WO2009101728A1 PCT/JP2008/068526 JP2008068526W WO2009101728A1 WO 2009101728 A1 WO2009101728 A1 WO 2009101728A1 JP 2008068526 W JP2008068526 W JP 2008068526W WO 2009101728 A1 WO2009101728 A1 WO 2009101728A1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
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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
- F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
- F01N3/106—Auxiliary oxidation catalysts
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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
- F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
- F01N2550/02—Catalytic activity of catalytic converters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
- F01N2560/026—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting NOx
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/14—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics having more than one sensor of one kind
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
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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 an oxidation catalyst failure diagnosis device, an oxidation catalyst failure diagnosis method, and an exhaust purification device for an internal combustion engine. More particularly, the present invention relates to an oxidation catalyst failure diagnosis device, an oxidation catalyst failure diagnosis method, and an exhaust purification device for an internal combustion engine that diagnose failure of an oxidation catalyst disposed downstream of a reduction catalyst that performs reduction of NO x using ammonia. .
- the exhaust gas discharged from an internal combustion engine such as a diesel engine contains nitrogen oxide (NO x ) that may affect the environment.
- NO x nitrogen oxide
- a selective reduction catalyst is disposed in the exhaust passage, and NO x is reduced and purified using ammonia in the selective reduction catalyst.
- An SCR (Selective Catalytic Reduction) system is known. This SCR system supplies a reducing agent such as a urea solution capable of generating ammonia into an exhaust passage upstream of the selective reduction catalyst, adsorbs the generated ammonia to the selective reduction catalyst, and flows into the selective reduction catalyst. the NO X in the exhaust gas is to selectively reduce and purify.
- the saturated adsorption amount of ammonia in the selective reduction catalyst used in this SCR system has a characteristic that varies depending on the catalyst temperature. Further, the selective reduction catalyst, the higher the actual ammonia adsorption rate for saturated adsorption amount of ammonia, and has a reduction efficiency is high characteristics of NO X. Therefore, the supply amount of the reducing agent such as the urea solution is controlled so that ammonia does not flow out downstream of the selective reduction catalyst and the actual adsorption rate with respect to the saturated adsorption amount is as high as possible.
- part of the generated ammonia may flow out downstream of the selective reduction catalyst due to an error in the supply amount of the reducing agent instructed by the control unit, deterioration with time of the SCR system, or the like.
- Ammonia is more toxic than NO x and should be avoided as much as possible from being released into the atmosphere without being used in the reduction reaction. Therefore, an oxidation catalyst is provided on the downstream side of the selective reduction catalyst, and when a part of the ammonia flows out downstream of the selective reduction catalyst, the ammonia is oxidized to generate nitrogen (N 2 ), water (H 2 O), There is an SCR system which is decomposed and released.
- the efficiency of the oxidation catalyst may decrease due to failures such as thermal deterioration, deterioration with time, cracks, and the like.
- failures such as thermal deterioration, deterioration with time, cracks, and the like.
- the ammonia flowing out downstream of the selective reduction catalyst cannot be sufficiently oxidized and decomposed, and ammonia may be released into the atmosphere.
- an exhaust emission control device configured to be able to determine deterioration of an oxidation catalyst has been proposed.
- an oxidation catalyst that is disposed downstream of the reduction catalyst and oxidizes ammonia in the exhaust
- a second concentration detection means that detects the ammonia concentration downstream of the oxidation catalyst
- an exhaust gas downstream of the oxidation catalyst And a second concentration estimating means for estimating the ammonia concentration at the second, wherein the difference between the ammonia concentration detected by the second concentration detecting means and the ammonia concentration estimated by the second concentration estimating means is a second predetermined value.
- JP 2006-125323 A (Claim 4, [0022] to [0027])
- the exhaust emission control device described in Patent Document 1 sets the difference between the ammonia concentration actually detected on the downstream side of the oxidation catalyst and the estimated ammonia concentration on the downstream side of the oxidation catalyst as the second predetermined value. In comparison, the deterioration of the oxidation catalyst is judged. Since the ammonia concentration downstream of the oxidation catalyst that is estimated or actually detected varies depending on the operating conditions of the internal combustion engine, the deterioration determination is performed based on a second predetermined value that is defined in advance. In some cases, the reliability of the diagnosis result may be lowered.
- the method for determining the deterioration of the oxidation catalyst described in Patent Document 1 may limit the operating conditions for performing the deterioration determination, or may reduce the reliability of the determination result.
- the oxidation catalyst failure diagnosis apparatus includes a calculation part for easily calculating the oxidation efficiency of the oxidation catalyst provided on the downstream side of the selective reduction catalyst, and the oxidation efficiency is lowered.
- the present inventors have found that the above-described problems can be solved by performing a failure diagnosis of the oxidation catalyst depending on whether or not the failure has been made, and the present invention has been completed. That is, an object of the present invention is to provide an oxidation catalyst failure diagnosis apparatus in which oxidation efficiency in an oxidation catalyst is easily calculated even under various operating conditions, and the oxidation catalyst failure diagnosis is performed accurately at a desired time.
- An object of the present invention is to provide an oxidation catalyst failure diagnosis method and an exhaust purification device for an internal combustion engine equipped with such an oxidation catalyst failure diagnosis device.
- a reducing agent capable of generating ammonia is supplied to the upstream side of the exhaust passage of the reduction catalyst, in an exhaust purification apparatus for selectively reducing and purging to the engine the NO X in the exhaust gas at the reduction catalyst, the reduction A failure diagnosis device for an oxidation catalyst for diagnosing a failure of an oxidation catalyst disposed on the downstream side of the catalyst, wherein the supply amount of the reducing agent is set so that a predetermined amount of ammonia flows out downstream of the reduction catalyst
- a failure determination unit that determines whether or not there is a failure of the oxidation catalyst compared to the above, and provides a failure diagnosis device for an oxidation catalyst characterized in that the above-described problems can be solved.
- the oxidation efficiency is the value of the upstream-side NO X sensor arranged upstream of the downstream and the oxidation catalyst of the reduction catalyst, the downstream side of the oxidation catalyst It is preferably calculated based on the value of the arranged downstream NO x sensor and the estimated NO x amount in the exhaust gas downstream of the reduction catalyst and upstream of the oxidation catalyst.
- the oxidation efficiency is estimated amount of NO X and the estimated amount of ammonia in the upstream side of the downstream and the oxidation catalyst of the reduction catalyst is arranged downstream of the oxidation catalyst the value of the downstream-side NO X sensor, preferably to be calculated based on.
- a purification ammonia amount calculation unit for calculating a purification ammonia amount necessary for purifying NO x in the exhaust gas flowing into the reduction catalyst, a reduction catalyst
- An ammonia-adsorbable amount calculation unit that subtracts the current estimated adsorption amount from the saturated adsorption amount according to the temperature of the gas to calculate the ammonia-adsorbable amount
- the reducing agent supply amount calculation unit includes the adsorbable amount and It is preferable to set the supply amount of the reducing agent by adding a predetermined amount to the reducing agent amount corresponding to the ammonia amount for purification.
- an exhaust temperature detection unit for detecting the exhaust temperature is provided, and the oxidation catalyst is detected when the amplitude of the exhaust temperature is within a predetermined range and the exhaust temperature is stable. It is preferable that failure diagnosis is performed.
- Another aspect of the present invention provides an exhaust purification system for an internal combustion engine that supplies a reducing agent capable of generating ammonia to an exhaust passage upstream of the reduction catalyst and selectively reduces and purifies NO x in the exhaust gas with the reduction catalyst.
- a method for diagnosing an oxidation catalyst disposed downstream of a reduction catalyst in an apparatus wherein a reducing agent is supplied so that a predetermined amount of ammonia flows out downstream of the reduction catalyst, and the predetermined amount of ammonia is converted into an oxidation catalyst.
- the oxidation catalyst failure diagnosis method is characterized in that the oxidation catalyst failure determination is performed by comparing the purification efficiency that is oxidized and purified by the oxidation catalyst when passing through a predetermined reference value.
- Still another aspect of the present invention is an exhaust gas purification apparatus for an internal combustion engine, comprising any of the oxidation catalyst failure diagnosis apparatuses described above.
- the oxidation catalyst failure diagnosis apparatus and oxidation catalyst failure diagnosis method of the present invention focusing on the characteristic that the NO X sensor also reacts with ammonia, the reduction is performed so that a predetermined amount of ammonia flows out downstream of the reduction catalyst. Since the agent is supplied and the ratio of ammonia that is oxidized by the oxidation catalyst disposed downstream of the reduction catalyst is calculated and failure diagnosis of the oxidation catalyst is performed, it can be performed at a desired time regardless of the operating state of the internal combustion engine. Failure diagnosis of the oxidation catalyst is performed with high accuracy.
- an oxidation catalyst failure diagnosis apparatus and an oxidation catalyst failure diagnosis method that can reduce the restriction on the timing of diagnosis and perform the oxidation catalyst failure diagnosis with high accuracy.
- the failure diagnosis device for diagnosing the failure of the oxidation catalyst is provided at a desired time regardless of the operation state and operation conditions of the internal combustion engine, Even when ammonia flows out downstream of the reduction catalyst, an exhaust purification device is provided in which ammonia is efficiently oxidized by the oxidation catalyst and is prevented from being released into the atmosphere.
- Embodiments of an oxidation catalyst failure diagnosis apparatus, a failure diagnosis method, and an exhaust gas purification apparatus including the failure diagnosis apparatus according to the present invention will be specifically described below with reference to the drawings.
- this embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
- symbol has shown the same member, and description is abbreviate
- the reducing agent supply device 20 used in the present embodiment includes a reducing agent injection valve 31 fixed to the exhaust pipe 11 on the upstream side of the reducing catalyst 13, and a storage tank 50 in which a urea aqueous solution as a reducing agent is stored.
- the reducing agent injection A control device 60 that controls the valve 31 and the pump 41 is provided.
- the DCU 60 is connected to the CAN 65.
- This CAN 65 is connected to a control unit 70 (hereinafter also referred to as “ECU: Electronic Control Unit”) 70 for controlling the operating state of the internal combustion engine, and the fuel injection amount and injection timing are connected to the CAN 65.
- ECU Electronic Control Unit
- the DCU 60 connected to the CAN 65 reads information on the CAN 65 and outputs information on the CAN 65.
- the ECU 70 and the DCU 60 are composed of separate control units and can exchange information via the CAN 65.
- the ECU 70 and the DCU 60 are configured as one control unit. It doesn't matter.
- the reducing agent injection valve 31 for example, an ON-OFF valve whose ON / OFF is controlled by duty control is used.
- the reducing agent pumped from the pump module 40 to the reducing agent injection valve 31 is maintained at a predetermined pressure, and when the reducing agent injection valve 31 is opened by a control signal sent from the DCU 60, the reducing agent enters the exhaust passage. Supplied.
- the pump module 40 includes a pump 41, which pumps the reducing agent in the storage tank 50 and pumps it to the reducing agent injection valve 31.
- the pump 41 includes, for example, an electric diaphragm pump or a gear pump, and drive control is performed by a signal sent from the DCU 60.
- the supply passage 58 that connects the pump 41 and the reducing agent injection valve 31 is provided with a pressure sensor 43, and the value detected by the pressure sensor 43 is output to the DCU 60 as a signal.
- feedback control of the pump 41 is performed based on the sensor value of the pressure sensor 43 so that the pressure value in the supply passage 58 is maintained at a predetermined value.
- the drive duty of the pump 41 is controlled to be larger, and the pressure in the supply passage 58 is higher than the predetermined value. In the control, the drive duty of the pump 41 is controlled to be small.
- the “pump drive duty” means the ratio of the pump drive time in one cycle in PWM (pulse width modulation) control.
- a circulation passage 59 is branched from the supply passage 58 and connected to the storage tank 50.
- An orifice 45 is provided in the middle of the circulation passage 59, and a pressure control valve 49 is provided closer to the storage tank 50 than the orifice 45. Since the reducing agent supply device 20 includes such a circulation passage 59, the pressure value in the supply passage 58 is reduced in a state where the reducing agent is pumped by the pump 41 that is feedback-controlled based on the detection value of the pressure sensor 43. When the predetermined value is exceeded, the pressure control valve 49 is opened, and a part of the reducing agent is recirculated into the storage tank 50.
- the pressure control valve 49 for example, a known check valve or the like is used.
- the pump module 40 is provided with a reverting valve 71, and when the reducing agent is not supplied by the reducing agent supply device 20, the pump 41 is driven to drive the pump module 40, the reducing agent injection valve 31, and the like.
- the reducing agent in the reducing agent supply system including the supply passage 58 is collected in the storage tank 50. Therefore, when the internal combustion engine 5 is stopped and the reducing agent is not supplied by the reducing agent supply device 20 under a temperature condition in which the reducing agent is likely to freeze, such as in cold weather, the reducing agent supply system 20 does not supply the reducing agent. When the reducing agent is prevented from freezing and then the operation of the internal combustion engine is resumed, there is no injection failure due to clogging in the reducing agent supply system.
- the reverting valve 71 is, for example, a switching valve having a function of switching the flow path of the reducing agent from the forward direction from the storage tank 50 to the pump module 40 to the reverse direction from the pump module 40 to the storage tank 50.
- the ignition switch of the internal combustion engine is turned off, the flow path is switched in the reverse direction, and the reducing agent is recovered in the storage tank 50.
- Each part of the reducing agent supply system of the reducing agent supply apparatus 20 is provided with heaters 92 to 97, respectively.
- These heaters 92 to 97 have a reducing agent that freezes partially or completely when the reducing agent is present in the reducing agent supply system, such as during cold weather. This is provided to prevent the supply control of the reducing agent by the injection valve 31 from being performed accurately.
- the heaters 92 to 97 are energized and controlled by the DCU 60. For example, based on the temperature of the reducing agent, outside air temperature, etc., power is supplied from the battery in a situation where it is determined that the reducing agent is in a temperature condition that causes the reducing agent to freeze in the reducing agent supply system.
- the agent supply system is heated.
- These heaters 92 to 97 are not particularly limited, and for example, a heating wire or the like is used.
- the reduction catalyst 13 disposed in the exhaust passage adsorbs ammonia generated by hydrolysis of the reducing agent injected and supplied by the reducing agent supply device 20, and NO X in the exhaust gas flowing in is absorbed. Reduce and purify. Therefore, when the amount of ammonia that is adsorbed is insufficient, part of the NO X is flow out to the downstream side of the reduction catalyst without being reduced, always more than a predetermined amount of ammonia adsorbed by the reduction catalyst 13 The supply amount of the reducing agent is controlled so as to be in the state of being performed. As shown in FIG. 2, the reduction catalyst 13 has a characteristic that the saturated adsorption amount (solid line A) of ammonia changes depending on the catalyst temperature.
- the exhaust gas purification apparatus reduces ammonia when controlling the supply amount of the reducing agent in the normal operation state of the internal combustion engine.
- the supply amount control is performed by setting a target adsorption amount (broken line B) smaller than the saturated adsorption amount so as not to flow out to the downstream side of the catalyst.
- the oxidation catalyst 12 is provided on the downstream side of the reduction catalyst 13, and ammonia flowing out without being adsorbed by the reduction catalyst 13 is oxidized. That is, the ammonia that flows out is oxidized in the oxidation catalyst 12, decomposed into nitrogen (N 2 ) and water (H 2 O), and released.
- a first NO x sensor 17 is provided between the reduction catalyst 13 and the oxidation catalyst 12, and a second NO x sensor 19 is provided further downstream of the oxidation catalyst 12.
- These of the NO X sensor 17 and 19, are known to exhibit a reaction in the ammonia produced by hydrolysis of the reducing agent as well as NO X. Therefore, the sensor value detected by the NO X sensor 17 and 19 has a total of the NO X concentration and the ammonia concentration in the exhaust gas.
- the oxidation catalyst 12 is disposed between the first NO x sensor 17 and the second NO x sensor 19, and the amount of NO x on the upstream side and the downstream side of the oxidation catalyst 12 changes almost.
- the amount of ammonia on the upstream side and downstream side of the oxidation catalyst 12 decreases. Therefore, if the subtraction sensor value integrated value of the (s1) (S1) from the sensor value of the second of the NO X sensor 19 (s2) integrated value of (S2) of the first of the NO X sensor 17, the predetermined time period The amount of ammonia (Uo) oxidized by the oxidation catalyst 12 is calculated.
- the ratio of ammonia oxidized by the oxidation catalyst 12 is calculated by dividing the oxidized ammonia amount (Uo) by the ammonia amount (Uu) upstream of the oxidation catalyst 12.
- this ratio is used for failure diagnosis of the oxidation catalyst.
- Control device for reducing agent supply device (oxidation catalyst failure diagnosis device) (1) Basic Configuration
- the DCU 60 provided in the exhaust gas purification apparatus 10 shown in FIG. 1 basically has various types of components existing on the CAN 65 so that an appropriate amount of reducing agent is supplied into the exhaust pipe 11. The operation control of the pump 41 and the reducing agent injection valve 31 is performed based on such information.
- the DCU 60 in the embodiment of the present invention further has a function as a failure diagnosis device for the oxidation catalyst 12 provided on the downstream side of the reduction catalyst 13.
- FIG. 1 shows a configuration example represented by functional blocks regarding the operation control of the reducing agent injection valve 31, the drive control of the pump 41, and the part relating to the failure diagnosis of the oxidation catalyst 13.
- the DCU 60 includes a CAN information extraction and generation unit (indicated as “CAN information extraction and generation” in FIG. 1), a pump drive control unit (indicated as “pump drive control” in FIG. 1), and a reducing agent supply amount calculation unit. (Indicated as “Ud supply amount calculation” in FIG. 1), a failure diagnosis unit (indicated as “failure diagnosis” in FIG. 1), and the like as main components. Specifically, each of these units is realized by executing a program by a microcomputer (not shown).
- the CAN information extraction and generation unit reads information existing on the CAN 65 including information on the operating state of the internal combustion engine 5 output from the ECU 70 and sensor values output from the temperature sensor and the NO X sensor, Output to each part.
- information on the operating state of the internal combustion engine including the fuel injection amount and the fuel injection timing, and sensor values of each sensor provided in the exhaust purification apparatus 10 are transmitted to the other units via the CAN information extraction and generation unit.
- the pump drive control unit continuously reads the sensor value of the pressure sensor 43 indicating the pressure of the reducing agent in the supply path 58 output from the CAN information extraction and generation unit, and the pump 41 is controlled based on this sensor value. Feedback control. As a result, the pressure in the supply path 58 is maintained in a substantially constant state.
- the pump 41 is an electric pump
- the pump duty ratio is controlled to increase to increase the pressure
- the duty ratio of the pump is controlled to be small in order to reduce the pressure.
- the reducing agent supply amount calculation unit subtracts the estimated adsorption amount of ammonia actually adsorbed from the target adsorption amount corresponding to the temperature of the reduction catalyst, and the deficiency amount.
- a reducing agent injection valve operating device (denoted as “Udv operating device” in FIG. 1) 67 for determining the supply amount of the reducing agent so that a minute amount of ammonia is generated and operating the reducing agent injection valve 31. Outputs an operation signal.
- the reducing agent supply amount calculation unit calculates the purification ammonia amount and the ammonia adsorption possible amount calculated by the purification ammonia amount calculation unit and the ammonia adsorption possible amount calculation unit described later. Is added to determine the amount of reducing agent necessary to generate the total ammonia amount, and a predetermined amount is added to determine the reducing agent supply amount. That is, in order to verify the oxidation efficiency of ammonia in the oxidation catalyst, the supply amount of the reducing agent is set so that a part of the ammonia flows out downstream of the reduction catalyst.
- the DCU 60 compares the target adsorption amount corresponding to the temperature of the reduction catalyst 13 with the estimated adsorption amount in a state where the reducing agent is supplied at a substantially constant pressure, and an insufficient amount of ammonia is generated. A necessary supply amount of the reducing agent is determined, and a control signal corresponding to the determined amount is generated and output to the reducing agent injection valve operating device 67. Then, the reducing agent injection valve 31 is controlled by the reducing agent injection valve operating device 67, and an appropriate amount of reducing agent is supplied into the exhaust pipe 11. The reducing agent supplied into the exhaust pipe 11 flows into the reduction catalyst 13 while being mixed with the exhaust gas, and is used for the reduction reaction of NO x contained in the exhaust gas. In this way, exhaust gas purification is performed.
- the DUC 60 provided in the exhaust emission control device 10 of the present embodiment includes the oxidation catalyst 12 failure diagnosis unit.
- the oxidation catalyst 12 plays an important role in oxidizing relatively highly toxic ammonia, the oxidation catalyst 12 is promptly replaced when there is a risk of failure of the oxidation catalyst 12. This is to prevent the release of air into the atmosphere.
- FIG. 3 shows the configuration of the oxidation catalyst failure diagnosis unit in the configuration of the DCU 60 in more detail.
- the failure diagnosis unit includes a purification ammonia amount calculation unit (indicated as “necessary purification amount calculation”), an ammonia adsorbable amount calculation unit (indicated as “adsorbable amount calculation”), and a reducing agent supply amount calculation unit. (Indicated as “Ud supply amount calculation”), exhaust temperature transition monitoring unit (indicated as “temperature transition monitoring”), oxidation efficiency calculation unit (indicated as “oxidation efficiency calculation”), failure determination unit ( “Denoted as” Failure judgment ".) Etc. as main elements. Each of these units is also specifically realized by executing a program by a microcomputer (not shown).
- purifying ammonia amount calculating unit based on the amount of NO X flowing into the reduction catalyst, and calculates the amount of ammonia (m0) required to reduce and purify them of the NO X in the reducing catalyst.
- the amount of NO X flowing into the reduction catalyst is calculated based on information such as the operating state of the exhaust temperature of the internal combustion engine, on the upstream side of the reduction catalyst 13 Alternatively, a NO x sensor may be arranged to calculate based on the detected sensor value.
- the ammonia adsorbable amount calculating unit subtracts the estimated adsorption amount currently adsorbed on the reduction catalyst from the saturated adsorption amount corresponding to the temperature of the reduction catalyst, and further calculates an adsorbable ammonia amount.
- the saturated adsorption amount of the reduction catalyst has a relationship that decreases as the catalyst temperature increases.
- the saturated adsorption amount corresponding to the catalyst temperature is obtained on the basis of the catalyst temperature obtained by the above.
- the estimated adsorption amount of ammonia is obtained by integrating a value obtained by subtracting the ammonia amount (m0) necessary for reducing and purifying NO X from the target adsorption amount in the reducing agent injection control that has been performed so far. Desired.
- the reducing agent supply amount calculation unit when performing a failure diagnosis of the oxidation catalyst, adds the ammonia adsorbable amount to the purification ammonia amount, and calculates the reducing agent amount sufficient to generate the total ammonia amount, Further, a predetermined amount is added to calculate the supply amount of the reducing agent.
- This reducing agent supply amount calculation unit is a part common to the reducing agent supply amount calculation unit for controlling the reducing agent supply amount in the normal operation state. Thus, the calculation of the reducing agent supply amount is performed.
- the DCU 60 provided in the exhaust purification device 10 of the present embodiment is provided with an exhaust temperature transition monitoring unit, and this exhaust temperature transition monitoring unit is provided for the temperature sensor 15 sent from the CAN information extraction and generation unit.
- the transition of the sensor value (exhaust temperature) is monitored to determine whether or not the state where the amplitude of the exhaust temperature is within a predetermined range has continued for a predetermined time or more. This is because when the exhaust gas temperature is unstable, the efficiency of the oxidation catalyst and the reduction catalyst may change, or the amount of ammonia that flows out may vary, leading to the reliability of the diagnosis results. This is because there is a case in which the lowering may occur. Therefore, even when the supply instruction amount is calculated by the above-described reducing agent supply amount calculation unit, if the exhaust temperature transition monitoring unit does not determine that the exhaust temperature is stable, a failure diagnosis is actually started. There is nothing to do.
- the oxidation efficiency calculation unit calculates the oxidation efficiency of ammonia by the oxidation catalyst after a reducing agent is supplied for failure diagnosis and a predetermined amount of ammonia flows out downstream of the reduction catalyst.
- the calculation of the ammonia oxidation efficiency in the oxidation efficiency calculation unit of the present embodiment is performed as follows.
- Nu N 0 - ⁇ Est ⁇ N 0 (3) It is expressed.
- this equation (5) in the oxidation efficiency calculation unit of the DCU provided in the exhaust purification apparatus of the present embodiment, the sensor values of the first and second NO x sensors and the estimated oxidation catalyst upstream side and of the amount of NO X in the group, the oxidation efficiency of the ammonia in the oxidation catalyst is calculated.
- the failure determination unit compares the ammonia oxidation efficiency value calculated by the oxidation efficiency calculation unit with a predetermined reference value, and determines that the oxidation catalyst has failed when the value is less than the reference value.
- the internal combustion engine is determined by determining the failure of the oxidation catalyst based on the ratio of the oxidized ammonia amount (Uo) to the ammonia amount upstream of the oxidation catalyst (Uu) rather than the absolute amount of oxidized ammonia. Regardless of the operating state of the engine, the failure diagnosis of the oxidation catalyst is performed with high accuracy.
- failure diagnosis is performed by obtaining the absolute amount of oxidized ammonia on the premise that a specified amount of ammonia flows out downstream of the reduction catalyst, there is a change in the operating state of the internal combustion engine or the reduction catalyst temperature. In addition, there may be an error in the amount of ammonia that flows out downstream of the reduction catalyst in the first place, and the amount of oxidized ammonia may decrease even though the oxidation catalyst has not failed.
- failure diagnosis is performed by determining the ratio of oxidized ammonia, which greatly affects the diagnosis result even when the amount of ammonia flowing out downstream of the reduction catalyst differs for each diagnosis. There is no.
- step S10 it is determined whether or not the exhaust gas temperature is stable.
- a temperature sensor (reference numeral 15 in FIG. 1) is provided on the upstream side of the reduction catalyst, the change of the sensor value is monitored, and the amplitude of the exhaust temperature is within a predetermined range. The determination is made by checking whether or not a certain state has passed for a predetermined time. If the temperature sensor is not provided, it may be determined whether the exhaust temperature is stable using the exhaust temperature estimated from the operating state of the internal combustion engine. This step S10 is repeated until it is determined that the exhaust temperature is stable.
- step S11 a purification ammonia amount is calculated. Specifically, the operating state of the internal combustion engine, the exhaust temperature, and the like are read by the DCU, the flow rate of NO x flowing into the reduction catalyst is obtained, and the amount of purification ammonia necessary for reducing this NO x is calculated.
- step S12 the ammonia adsorption possible amount is calculated. Specifically, after the temperature of the reduction catalyst is obtained by calculation based on the sensor values of the temperature sensors arranged upstream and downstream of the reduction catalyst, it is estimated from the saturated adsorption amount corresponding to the temperature of the reduction catalyst. The adsorption amount is subtracted, and the ammonia adsorption possible amount is calculated.
- step S13 the amount of ammonia for purification obtained in step S10 and the ammonia adsorbable amount obtained in step S11 are added, and the amount of reducing agent necessary to generate the total amount of ammonia is calculated.
- step S14 a predetermined amount is further added to the reducing agent amount calculated in step S12 to determine the reducing agent supply instruction value, and then in step S15, the reducing agent is supplied to the operating device of the reducing agent injection valve. Is instructed to supply. As a result, a part of the ammonia generated from the supplied reducing agent flows into the downstream side of the reduction catalyst.
- the ammonia corresponding to the added reducing agent flows out to the downstream side of the reduction catalyst, but the concentration of ammonia released into the atmosphere flows out to the downstream side of the oxidation catalyst.
- the upper limit is 31 ppm if the efficiency at which ammonia is oxidized by the oxidation catalyst is 20%, and 100 ppm if the efficiency at which ammonia is oxidized is 80%
- the amount of reducing agent to be added is determined so that ammonia having a concentration equal to or lower than the upper limit flows out to the downstream side of the reduction catalyst.
- step S16 the first NO x sensor value (s1) on the upstream side of the oxidation catalyst is read and integrated, and the sensor value (s2) of the second NO x sensor on the downstream side of the oxidation catalyst is read. Integration is performed.
- the estimated reduction efficiency of NO x in the reduction catalyst is calculated on the upstream side of the oxidation catalyst based on the flow rate, temperature, NO x concentration of the exhaust gas discharged from the internal combustion engine, the temperature of the reduction catalyst, etc.
- An estimated amount (Nu) of the NO x amount at is calculated.
- step S17 the first of the NO X sensor value of the sensor (s1) integrated value of (S1), the second of the NO X sensor value of the sensor (s2) integrated value of (S2) and reducing catalyst downstream
- the ammonia oxidation efficiency (X) in the oxidation catalyst is calculated based on the estimated amount (Nu) of the NO x amount at.
- step S18 it is determined whether or not the calculated oxidation efficiency (X) is equal to or greater than a predetermined reference value (X0). If the oxidation efficiency is equal to or higher than the reference value (X0), it is considered that the oxidation catalyst is functioning without a major failure, and it is determined that there is no failure of the oxidation catalyst. On the other hand, if the oxidation efficiency is less than the reference value (X0), it is considered that the oxidation catalyst has failed and the ability to oxidize ammonia has deteriorated, and it is determined that the oxidation catalyst has failed. Is done.
- the supply instruction amount of the reducing agent is calculated.
- new amount of NO X flowing into the reduction catalyst is small as possible in a state where the driver releases the accelerator, the amount of purifying ammonia substantially zero.
- the ammonia adsorbable amount becomes zero.
- the DCU is configured so that the driver can detect the state where the accelerator is released or the ammonia adsorption saturation state of the reduction catalyst, and the step of calculating at least one of the purification ammonia amount and the ammonia adsorption possible amount is omitted. You may do it.
- the exhaust purification apparatus of the first embodiment includes NO X sensors on the upstream side and the downstream side of the oxidation catalyst, whereas the exhaust purification apparatus of the present embodiment includes NO X on the upstream side of the oxidation catalyst. It differs from the exhaust emission control device of the first embodiment in that no sensor is provided.
- description of points that are common to the first embodiment will be omitted, and points that are different from the first embodiment will be mainly described.
- the exhaust purification device 110 of the present embodiment includes a NO x sensor 117 on the downstream side of the oxidation catalyst 12, but does not include a NO x sensor on the upstream side of the oxidation catalyst 12. Instead, the DCU 160 is provided with a calculation unit (indicated as “Uu calculation” in FIG. 5) for estimating the ammonia amount downstream of the oxidation catalyst. That is, the exhaust purification device 110 of the present embodiment obtains the ammonia amount on the upstream side of the oxidation catalyst using the calculated value instead of the sensor value of the NO x sensor.
- the ammonia amount (Uu) on the upstream side of the oxidation catalyst is obtained by calculation in the DCU 160. Further, considering that the sensor value of the NO x sensor 117 on the downstream side of the oxidation catalyst is the total value of the NO x concentration and the ammonia concentration, the amount of ammonia (Uo) oxidized by the oxidation catalyst is the upstream side of the oxidation catalyst. the amount of NO X from the total amount of (Nu) and ammonia amount of the oxidation catalyst upstream (Uu), obtained by subtracting the sensor value of the NO X sensor 117 integrated value of (S3) a (s3).
- the oxidation efficiency calculation unit of the DCU 160 provided in the exhaust purification device 110 of the present embodiment calculates the sensor value of the NO X sensor, the estimated NO X amount upstream of the oxidation catalyst, and Based on the ammonia amount, the oxidation efficiency of ammonia in the oxidation catalyst is calculated.
- the failure determination unit compares the oxidation efficiency value of ammonia calculated by the oxidation efficiency calculation unit with a predetermined reference value, and oxidizes when the value is less than the reference value. It is determined that the catalyst has failed. Even If this is not provided with the NO X sensor of the oxidation catalyst upstream, regardless of the operating state of the internal combustion engine, to ammonia amount of the oxidation catalyst upstream (Uu), oxidized ammonia amount (Uo)
- the failure diagnosis of the oxidation catalyst can be performed on the basis of the ratio.
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Abstract
Description
そこで、酸化触媒の劣化判定が行えるように構成された排気浄化装置が提案されている。具体的には、還元触媒の下流側に配設され、排気中のアンモニアを酸化する酸化触媒と、酸化触媒の排気下流におけるアンモニア濃度を検出する第2の濃度検出手段と、酸化触媒の排気下流におけるアンモニア濃度を推定する第2の濃度推定手段と、を備え、第2の濃度検出手段により検出されたアンモニア濃度と第2の濃度推定手段により推定されたアンモニア濃度との差が第2の所定値以上となったときに、酸化触媒が劣化したと判定する排気浄化装置が開示されている(特許文献1参照)。
したがって、特許文献1に記載された酸化触媒の劣化判定の方法は、劣化判定を行う運転条件が制約されたり、判定結果の信頼性が低くなったりするおそれがある。
なお、それぞれの図中、同じ符号を付してあるものについては同一の部材を示しており、適宜説明が省略されている。
1.排気浄化装置
まず、酸化触媒の故障診断装置が備えられた本発明の第1の実施の形態にかかる排気浄化装置の基本的な構成について図1を参照しつつ説明する。
図1に示す排気浄化装置10は、還元剤としての尿素水溶液を、排気通路中に配設された還元触媒13の上流側に噴射供給し、還元触媒13において排気ガス中に含まれるNOXを選択的に還元浄化する排気浄化装置10である。この排気浄化装置10は、内燃機関5に接続された排気管11の途中に配設され、排気ガス中に含まれるNOXを選択的に還元するための還元触媒13と、還元触媒13の上流側で排気管11内に還元剤を噴射供給するための還元剤噴射弁31を含む還元剤供給装置20と、還元触媒13の下流側に配置された酸化触媒12とを主たる要素として備えている。
例えば、本実施形態で使用する還元剤供給装置20は、還元触媒13の上流側で排気管11に固定された還元剤噴射弁31と、還元剤としての尿素水溶液が貯蔵された貯蔵タンク50と、貯蔵タンク50内の還元剤を還元剤噴射弁31に対して圧送するポンプ41を含むポンプモジュール40と、排気管11内に噴射供給する還元剤の供給量を制御するために、還元剤噴射弁31やポンプ41の制御を行う制御装置(以下、「DCU:Dosing Control Unit」と称する。)60を備えている。
なお、本実施形態では、ECU70とDCU60とが別のコントロールユニットからなり、CAN65を介して情報のやり取りができるようにされているが、これらのECU70とDCU60とが一つのコントロールユニットとして構成されていても構わない。
なお、「ポンプの駆動デューティ」とは、PWM(pulse width modulation)制御において、1周期当たりに占めるポンプの駆動時間の割合を意味している。
このリバーティングバルブ71は、例えば、還元剤の流路を、貯蔵タンク50からポンプモジュール40へ向かう順方向から、ポンプモジュール40から貯蔵タンク50へ向かう逆方向に切り替える機能を持った切換弁であり、内燃機関のイグニッションスイッチをオフにしたときに、流路が逆方向に切り換えられ還元剤が貯蔵タンク50内に回収される。
これらのヒーター92~97についても、特に制限されるものではなく、例えば、電熱線等が用いられる。
この還元触媒13は、図2に示すように、触媒温度によってアンモニアの飽和吸着量(実線A)が変化する特性をもっている。アンモニアはNOXと比較しても有害性が高いことが知られているため、本実施形態の排気浄化装置では、内燃機関の通常運転状態における還元剤の供給量制御を行うにあたり、アンモニアが還元触媒の下流側に流出しないように、飽和吸着量よりも小さい目標吸着量(破線B)を設定して、供給量制御が行われる。
(1)基本的構成
図1に示す排気浄化装置10に備えられたDCU60は、基本的には、適切な量の還元剤が排気管11中に供給されるように、CAN65上に存在する様々な情報を基にポンプ41及び還元剤噴射弁31の動作制御が行われる。また、本発明の実施の形態におけるDCU60は、さらに還元触媒13の下流側に備えられた酸化触媒12の故障診断装置としての機能を備えている。
一方、還元剤供給量演算部は、酸化触媒の故障診断を行う際には、後述する浄化用アンモニア量演算部及びアンモニア吸着可能量演算部で算出される浄化用アンモニア量とアンモニア吸着可能量とを加算した合計アンモニア量が生成されるために必要な還元剤量を求めるとともに、さらに所定量を加算して還元剤の供給量を決定する。すなわち、酸化触媒におけるアンモニアの酸化効率を検証するために、一部のアンモニアを還元触媒の下流側に流出させるように還元剤の供給量が設定される。
図1に示す排気浄化装置10による排気ガス中のNOXの還元浄化は以下のように行われる。
内燃機関の運転時において、貯蔵タンク50内の還元剤は、ポンプ41によって汲み上げられ、還元剤噴射弁31に向けて圧送される。このとき、ポンプモジュール40に備えられたポンプ41の下流側の圧力センサ43のセンサ値に基づき、センサ値が所定値未満の場合にはポンプ41の出力を高める一方、センサ値が所定値を超えそうな場合には圧力制御弁49を介して還元剤が貯蔵タンク50に戻されて減圧される。これによって、還元剤噴射弁31に向けて圧送される還元剤の圧力がほぼ一定の値に維持される。
ここで、本実施形態の排気浄化装置10に備えられたDUC60には、酸化触媒12の故障診断部が備えられている。上述したように、酸化触媒12は、比較的毒性の高いアンモニアを酸化する重要な役割を担っているため、酸化触媒12に故障のおそれがある場合には速やかに酸化触媒の交換を行い、アンモニアを大気中に放出させないようにするためである。
図3は、DCU60の構成のうちの酸化触媒の故障診断部の構成をさらに詳細に表している。この故障診断部は、浄化用アンモニア量演算部(「浄化必要量演算」と表記。)と、アンモニア吸着可能量演算部(「吸着可能量演算」と表記。)と、還元剤供給量演算部(「Ud供給量演算」と表記。)と、排気温度推移監視部(「温度推移監視」と表記。)と、酸化効率演算部(「酸化効率演算」と表記。)と、故障判定部(「故障判定」と表記。)等を主要な要素として備えている。これらの各部についても、具体的にはマイクロコンピュータ(図示せず)によるプログラムの実行によって実現される。
したがって、上述の還元剤供給量演算部で供給指示量が算出された場合であっても、排気温度推移監視部において、排気温度が安定していると判別されないときには、実際に故障診断が開始されることがない。
酸化触媒でのアンモニアの酸化効率(X)は、酸化触媒上流側のアンモニア量(Uu)に対する酸化触媒で酸化されたアンモニア量(Uo)の比率であり、
X=Uo/Uu …(1)
と表される。
Uu=S1-Nu …(2)
と表される。
この酸化触媒上流側のNOX量(Nu)は、排気ガスの温度や流量、還元触媒上流側でのNOXの流量、還元触媒上流側でのNO2とNOとの比率、アンモニア推定吸着量、還元触媒の推定HC(炭化水素)被毒量等を基にした推定還元触媒効率(ηEst)と、還元触媒上流側のNOX量(N0)とを用いて、
Nu=N0-ηEst×N0 …(3)
と表される。
Uo=S1-S2 …(4)
と表される。
X=(S1-S2)/(S1-Nu) …(5)
と表される。
この式(5)に示すように、本実施形態の排気浄化装置に備えられたDCUの酸化効率演算部では、第1及び第2のNOXセンサのセンサ値と、推定される酸化触媒上流側のNOX量とを基にして、酸化触媒におけるアンモニアの酸化効率が算出される。
すなわち、規定量のアンモニアを還元触媒下流側に流出させる前提で、酸化されたアンモニアの絶対量を求めることにより故障診断が行われると、内燃機関の運転状態や還元触媒温度に変化があった場合に、そもそも還元触媒下流側に流出したアンモニア量に誤差が生まれ、酸化触媒が故障していないにもかかわらず酸化されたアンモニア量が減ってしまう場合がある。これに対し、酸化されたアンモニアの比率を求めて故障診断が行われることにより、還元触媒下流側に流出するアンモニア量がその診断毎に異なる場合であっても、診断結果に大きく影響を与えることがない。
次に、酸化触媒の故障診断方法の具体的なルーチンの一例を図4のフローを参照しつつ説明する。なお、このルーチンは、常時実行されてもよく、あるいは一定時間ごとの割り込みによって実行されてもよい。
排気温度が安定していると判別されるまで、このステップS10が繰り返し行われる。
次いで、ステップS12においてアンモニア吸着可能量が算出される。具体的には、還元触媒の上流側及び下流側に配置された温度センサのセンサ値を基に、還元触媒の温度が演算によって求められた後、還元触媒の温度に応じた飽和吸着量から推定吸着量が差し引かれ、アンモニア吸着可能量が算出される。
次いで、ステップS14において、ステップS12で算出された還元剤量にさらに所定量加算されて還元剤の供給指示値が決定された後、ステップS15において、還元剤噴射弁の操作装置に対して還元剤の供給の指示が行われる。これによって、供給される還元剤から生成されるアンモニアの一部が、還元触媒の下流側に流出する状態になる。
例えば、排気ガス規制のアンモニア濃度の基準値が25ppmである場合に、酸化触媒でアンモニアが酸化される効率が20%であれば31ppm、アンモニアが酸化される効率が80%であれば100ppmを上限として、この上限以下の濃度のアンモニアが還元触媒の下流側に流出するように、加算する還元剤量を決定する。
次に、本発明の第2の実施の形態にかかる酸化触媒の故障診断装置を備えた排気浄化装置について説明する。第1の実施の形態の排気浄化装置が、酸化触媒の上流側及び下流側のそれぞれにNOXセンサを備えているのに対し、本実施形態の排気浄化装置は、酸化触媒上流側のNOXセンサを備えていない点で、第1の実施の形態の排気浄化装置とは異なっている。
以下、第1の実施の形態と共通する点については説明を省略し、第1の実施の形態と異なる点を中心に説明する。
第1の実施の形態で述べたとおり、アンモニアの酸化効率(X)は、酸化触媒上流側のアンモニア量(Uu)に対する酸化触媒で酸化されたアンモニア量(Uo)の比率であり、
X=Uo/Uu …(1)
と表される。
また、酸化触媒下流側のNOXセンサ117のセンサ値が、NOX濃度とアンモニア濃度との合計値であることを考慮すると、酸化触媒で酸化されたアンモニア量(Uo)は、酸化触媒上流側のNOX量(Nu)と酸化触媒上流側のアンモニア量(Uu)との合計量から、NOXセンサ117のセンサ値(s3)を積分した値(S3)を差し引くことにより求められる。酸化触媒上流側のNOX量(Nu)及び酸化触媒上流側のアンモニア量(Uu)はそれぞれ演算により推定量として求められるため、酸化触媒で酸化されたアンモニア量(Uo)は、
Uo=(Nu+Uu)-S3 …(6)
と表される。
X={(Nu+Uu)-S3}/Uu …(7)
と表される。
この式(7)に示すように、本実施形態の排気浄化装置110に備えられたDCU160の酸化効率演算部は、NOXセンサのセンサ値と、推定される酸化触媒上流側のNOX量及びアンモニア量とを基にして、酸化触媒におけるアンモニアの酸化効率を算出する。
Claims (7)
- アンモニアを生成可能な還元剤を還元触媒の上流側の排気通路に供給し、前記還元触媒で排気中のNOXを選択的に還元浄化する内燃機関の排気浄化装置における、前記還元触媒の下流側に配置された酸化触媒の故障診断を行うための酸化触媒の故障診断装置において、
所定量の前記アンモニアが前記還元触媒の下流側に流出するように前記還元剤の供給量を設定する還元剤供給量演算部と、
前記還元触媒の下流側に流出した前記所定量のアンモニアが前記酸化触媒を通過する際に前記酸化触媒で酸化される効率を求める酸化効率演算部と、
前記酸化効率を所定の基準値と比較して前記酸化触媒の故障の有無の判定を行う故障判定部と、
を備えることを特徴とする酸化触媒の故障診断装置。 - 前記酸化効率は、前記還元触媒の下流側かつ前記酸化触媒の上流側に配置された上流側NOXセンサの値と、前記酸化触媒の下流側に配置された下流側NOXセンサの値と、前記還元触媒の下流側かつ前記酸化触媒の上流側における前記排気中の推定NOX量と、を基に算出されることを特徴とする請求の範囲の第1項に記載の酸化触媒の故障診断装置。
- 前記酸化効率は、前記還元触媒の下流側かつ前記酸化触媒の上流側における推定NOX量及び推定アンモニア量と、前記酸化触媒の下流側に配置された下流側NOXセンサの値と、を基に算出されることを特徴とする請求の範囲の第1項に記載の酸化触媒の故障診断装置。
- 前記還元触媒に流入する前記排気中のNOXを浄化するために必要な浄化用アンモニア量を演算する浄化用アンモニア量演算部と、
前記還元触媒の温度に応じた飽和吸着量から現在の推定吸着量を減算して、前記アンモニアの吸着可能量を算出するアンモニア吸着可能量演算部と、を備え、
前記還元剤供給量演算部は、前記吸着可能量及び前記浄化用アンモニア量に対応する還元剤量に所定量加算して前記還元剤の供給量を設定することを特徴とする請求の範囲の第1項~第3項のいずれか一項に記載の酸化触媒の故障診断装置。 - 排気温度を検出する排気温度検出部を備え、
前記排気温度の振幅が所定の範囲内にあり前記排気温度が安定しているときに前記酸化触媒の故障診断が行われることを特徴とする請求の範囲の第1項~第4項のいずれか一項に記載の酸化触媒の故障診断装置。 - アンモニアを生成可能な還元剤を還元触媒の上流側の排気通路に供給し、前記還元触媒で排気中のNOXを選択的に還元浄化する内燃機関の排気浄化装置における、前記還元触媒の下流側に配置された酸化触媒の故障診断方法において、
所定量の前記アンモニアが前記還元触媒の下流側に流出するように前記還元剤を供給し、
前記所定量のアンモニアが前記酸化触媒を通過する際に前記酸化触媒で酸化浄化される浄化効率を所定の基準値と比較して前記酸化触媒の故障判定を行うことを特徴とする酸化触媒の故障診断方法。 - 請求の範囲の第1項~第5項のいずれか一項に記載の酸化触媒の故障診断装置を備えることを特徴とする内燃機関の排気浄化装置。
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
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JP2013517409A (ja) * | 2010-01-13 | 2013-05-16 | エミテック ゲゼルシヤフト フユア エミツシオンス テクノロギー ミツト ベシユレンクテル ハフツング | 液体還元剤のためのインジェクタを有するデバイス |
Families Citing this family (43)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4692911B2 (ja) * | 2008-09-18 | 2011-06-01 | トヨタ自動車株式会社 | NOxセンサの出力較正装置及び出力較正方法 |
JP5495678B2 (ja) * | 2009-08-28 | 2014-05-21 | 三輪精機株式会社 | 尿素噴射装置および電磁ポンプ |
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US11932080B2 (en) | 2020-08-20 | 2024-03-19 | Denso International America, Inc. | Diagnostic and recirculation control systems and methods |
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001221037A (ja) * | 2000-02-08 | 2001-08-17 | Toyota Motor Corp | 内燃機関の排気浄化装置 |
JP2006022735A (ja) * | 2004-07-08 | 2006-01-26 | Yasuo Saito | ディーゼル内燃機関の排気ガス処理装置及び処理方法 |
JP2006125323A (ja) * | 2004-10-29 | 2006-05-18 | Nissan Diesel Motor Co Ltd | 排気浄化装置 |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3316066B2 (ja) * | 1993-12-22 | 2002-08-19 | 富士重工業株式会社 | 排気ガス浄化装置の故障診断装置 |
JPH09203313A (ja) * | 1995-11-20 | 1997-08-05 | Mazda Motor Corp | 触媒の劣化検出装置 |
JP2000027627A (ja) * | 1998-07-13 | 2000-01-25 | Hino Motors Ltd | 排気ガス浄化触媒用還元剤保温装置及びそれを組込んだ排気ガス浄化装置 |
JP2003120399A (ja) * | 2001-10-09 | 2003-04-23 | Toyota Motor Corp | NOxセンサ異常検出装置 |
JP4785356B2 (ja) * | 2004-07-13 | 2011-10-05 | スタープラスチック工業株式会社 | 電子レンジ加熱用袋 |
-
2008
- 2008-02-15 JP JP2008033913A patent/JP5258319B2/ja not_active Expired - Fee Related
- 2008-10-14 US US12/866,963 patent/US8413422B2/en not_active Expired - Fee Related
- 2008-10-14 CN CN2008801240984A patent/CN101918687B/zh not_active Expired - Fee Related
- 2008-10-14 WO PCT/JP2008/068526 patent/WO2009101728A1/ja active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001221037A (ja) * | 2000-02-08 | 2001-08-17 | Toyota Motor Corp | 内燃機関の排気浄化装置 |
JP2006022735A (ja) * | 2004-07-08 | 2006-01-26 | Yasuo Saito | ディーゼル内燃機関の排気ガス処理装置及び処理方法 |
JP2006125323A (ja) * | 2004-10-29 | 2006-05-18 | Nissan Diesel Motor Co Ltd | 排気浄化装置 |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2013517409A (ja) * | 2010-01-13 | 2013-05-16 | エミテック ゲゼルシヤフト フユア エミツシオンス テクノロギー ミツト ベシユレンクテル ハフツング | 液体還元剤のためのインジェクタを有するデバイス |
WO2012117183A1 (fr) | 2011-03-02 | 2012-09-07 | Peugeot Citroen Automobiles Sa | Procede de diagnostic d'un catalyseur d'oxydation par mesure du taux d'oxydes d'azote en aval d'un organe de reduction catalytique selective |
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