WO2014184635A1 - Appareil de commande de gaz d'échappement pour moteur à combustion interne - Google Patents

Appareil de commande de gaz d'échappement pour moteur à combustion interne Download PDF

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Publication number
WO2014184635A1
WO2014184635A1 PCT/IB2014/000718 IB2014000718W WO2014184635A1 WO 2014184635 A1 WO2014184635 A1 WO 2014184635A1 IB 2014000718 W IB2014000718 W IB 2014000718W WO 2014184635 A1 WO2014184635 A1 WO 2014184635A1
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WO
WIPO (PCT)
Prior art keywords
oxidation catalyst
burn
filter
exhaust gas
amount
Prior art date
Application number
PCT/IB2014/000718
Other languages
English (en)
Inventor
Hidetaka Shibata
Tomohiko Matsushita
Yasuaki Nakano
Original Assignee
Toyota Jidosha Kabushiki Kaisha
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Jidosha Kabushiki Kaisha filed Critical Toyota Jidosha Kabushiki Kaisha
Priority to EP14747700.4A priority Critical patent/EP2997241A1/fr
Publication of WO2014184635A1 publication Critical patent/WO2014184635A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F01N3/025—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust
    • F01N3/0253—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/103—Oxidation catalysts for HC and CO only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/04—Sulfur or sulfur oxides
    • 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
    • F01N2900/1612—SOx amount trapped in catalyst
    • 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 invention relates to an exhaust gas control apparatus for an internal combustion engine, in which an oxidation catalyst and a filter that traps particulate matter are provided in an exhaust passage.
  • an exhaust gas control apparatus in which a filter and an oxidation catalyst for purifying exhaust gas are provided in an exhaust passage, the oxidation catalyst oxidizes, and thus purifies, unburned components in exhaust gas, and the filter traps particulate matter.
  • the oxidation catalyst oxidizes, and thus purifies, unburned components in exhaust gas, and the filter traps particulate matter.
  • fuel is added into the exhaust passage to raise the catalyst bed temperature of the oxidation catalyst.
  • the temperature of the filter is raised by the heat of the exhaust gas when the catalyst bed temperature of the oxidation catalyst is raised in this way and the particulate matter is consequently burned off.
  • the exhaust gas from an internal combustion engine includes sulfur oxide in addition to unburned components and particulate matter.
  • This sulfur oxide is adsorbed by the oxidation catalyst and when it continues to accumulate, the catalyst function may decline. Therefore, in the exhaust gas control apparatus, in addition to the burn-off process for the particulate matter described above, fuel is added into the exhaust passage to raise the catalyst bed temperature of the oxidation catalyst and place the oxidation catalyst in a low oxygen concentration environment. In this way, the sulfur oxide that has accumulated in the oxidation catalyst is reduced and desorbed by the added fuel.
  • JP 2006-291823 A when a required temperature increase in the catalyst bed temperature in the burn-off process for particulate matter is higher than a required temperature increase in the reduction process for sulfur oxide, the burn-off process for particulate matter is performed.
  • the burn-off process for particulate matter is performed.
  • the sulfur dioxide that has been desorbed from the oxidation catalyst may flow into the filter and be oxidized again by the heat of the filter.
  • smoke is generated just as described above.
  • the reoxidation of the sulfur dioxide in the filter is able to be suppressed by increasing to the fuel additive amount and placing the filter in an environment with a low oxygen concentration.
  • there are trade-offs such as the fuel efficiency deteriorating and unburned fuel becoming white smoke and being discharged, so the generation of white smoke is unable to be sufficiently resolved.
  • the invention thus provides an exhaust gas control apparatus for an internal combustion engine, which suppresses white smoke from being generated due to sulfate generated from sulfur oxide that has accumulated in an oxidation catalyst.
  • a first aspect of the invention relates to an exhaust gas control apparatus for an internal combustion engine, which includes an oxidation catalyst provided in an exhaust passage of the internal combustion engine, a filter that traps particulate matter, and a controller.
  • the filter is provided in the exhaust passage of the internal combustion engine, and is provided on a downstream side of the oxidation catalyst in an exhaust gas flow direction.
  • the controller is configured to execute a burn-off process and a reduction process.
  • the burn-off process is a process to burn off particulate matter trapped in the filter, by adding fuel upstream of the oxidation catalyst, in the exhaust gas flow direction.
  • the reduction process is a process to reduce and desorb sulfur oxide accumulated in the oxidation catalyst.
  • This reduction process includes an execution condition for the reduction process, and the execution condition is that a catalyst bed temperature of the oxidation catalyst in the reduction process be lower than a target temperature of the catalyst bed temperature of the oxidation catalyst in the burn-off process. Therefore, the reduction process for sulfur oxide is able to be performed in an environment in which the catalyst bed temperature of the oxidation catalyst and the temperature of the filter are low, compared to when the reduction process for sulfur oxide is performed in conjunction with the burn-off process for particulate matter.
  • the controller is configured to prohibit an execution of the burn-off process in case of an accumulation amount of sulfur oxide in the oxidation catalyst being larger than an allowable amount. Therefore, the burn-off process for particulate matter is performed in an environment in which the accumulation amount of sulfur oxide in the oxidation catalyst is low, so the amount of sulfur dioxide that flows into the filter from the oxidation catalyst while the burn-off process is being executed is able to be reduced. Therefore, even if regeneration of sulfur dioxide has occurred in the filter, the reoxidized amount is decreased, and the generation of sulfate caused by this reoxidation is also able to be suppressed.
  • the burn-off process for particulate matter is prohibited on a condition that the accumulation amount of sulfur oxide in the oxidation catalyst is larger than the allowable amount. Instead, however, when the execution condition for the burn-off process is satisfied, a timing at which the burn-off process is started may be delayed until the accumulation amount of sulfur oxide in the oxidation catalyst becomes equal to or less than the allowable amount through (or thanks to) the execution of the reduction process. Alternatively, the timing at which the burn-off process for particulate matter is started may be delayed until a period of time for (or during) which the reduction process for sulfur oxide is executed reaches a predetermined period of time.
  • the burn-off process for particulate matter is performed in an environment in which the accumulation amount of sulfur oxide in the oxidation catalyst is small. Therefore, the amount of sulfur dioxide that flows into the filter from the oxidation catalyst while the burn-off process is being executed is able to be reduced. Therefore, even if regeneration of sulfur dioxide has occurred in the filter, the reoxidized amount is decreased, and the generation of sulfate caused by this reoxidation is also able to be suppressed.
  • the reduction process for sulfur oxide may also be executed when the catalyst bed temperature is equal to or lower than an upper limit temperature at which desorbed sulfur dioxide in the oxidation catalyst does not reoxidize. According to this kind of structure, the generation of sulfate when the reduction process for sulfur oxide is performed is able to be effectively suppressed.
  • a carried amount of platinum-based metal per unit volume of a carrier of the filter may be less than a carried amount of platinum-based metal per unit volume of a carrier of the oxidation catalyst.
  • the amount of sulfur dioxide adsorbed by the carrier of the oxidation catalyst increases, and the amount of sulfur dioxide that flows into the filter without being adsorbed by the oxidation catalyst decreases. As a result, the generation of sulfate caused by sulfur dioxide flowing into the heated filter is able to be suppressed.
  • the filter even if sulfur dioxide has flowed in from the oxidation catalyst, the oxidative power of the filter is low, so reoxidation of the sulfur dioxide is able to be suppressed. Therefore, employing this kind of structure enables the amount of sulfate that is discharged from the filter to be further reduced.
  • a carrier on which a platinum-based metal is not carried may also be employed.
  • the oxidation catalyst may be a catalyst in which the carrier of the oxidation catalyst is an alumina-based metal, and the carried amount of platinum-based metal per 1 liter of the carrier of the oxidation catalyst is equal to or greater than 3.0 g.
  • the filter may be a filter in which the carried amount of platinum-based metal per 1 liter of the carrier of the filter is equal to or less than 1.0 g.
  • FIG. 1 is a view showing a frame format of the general structure of an internal combustion engine and an exhaust gas control apparatus thereof;
  • FIG. 2 is a flowchart illustrating a routine for executing a burn-off process and a reduction process
  • FIG. 3 is a time chart showing a shift in an execution condition for the burn-off process, an amount of fuel added, a catalyst bed temperature of an oxidation catalyst, an amount of sulfur dioxide that flows into a filter from the oxidation catalyst, an amount of sulfate discharged from the filter, and an accumulation amount of sulfur oxide in the oxidation catalyst;
  • FIG. 4 is a flowchart illustrating a routine for executing a reduction process
  • FIG. 5 is a flowchart illustrating a routine for executing a burn-off process
  • FIG. 6 is a time chart showing a shift in a running distance, an accumulation amount of sulfur oxide in the oxidation catalyst, an executing flag for the reduction process, a prohibiting flag for the burn-off process, and an execution mode of the burn-off process.
  • an injection valve 12 that injects fuel into a combustion chamber 11 of an internal combustion engine 10 is provided in the internal combustion engine 10.
  • An adding valve 20 that adds fuel into an exhaust passage 13, an oxidation catalyst 21, and a filter 22, are provided in this order from an upstream side in the exhaust passage 13.
  • the oxidation catalyst 21 oxidizes and purifies unburned fuel in the exhaust gas.
  • the filter 22 traps particulate matter that is in the exhaust gas.
  • the oxidation catalyst 21 is a catalyst in which a carrier is formed by an alumina-based metal, and 3.5 grams of platinum particles (Pt) per 1 liter are carried on this carrier.
  • the filter 22 is a filter in which a carrier is formed by cordierite or silicon carbide, and 0.5 grams of platinum particles per 1 liter are carried on this carrier.
  • a bed temperature sensor 30 that detects a temperature of the carrier of the oxidation catalyst 21, i.e., a catalyst bed temperature of the oxidation catalyst 21, is mounted to the oxidation catalyst 21.
  • a filter temperature sensor 31 that detects a temperature of the carrier of the filter 22 is mounted to the filter 22.
  • a differential pressure sensor 32 is provided in the exhaust passage 13. This differential pressure sensor 32 detects a difference between an internal pressure of a portion upstream of the filter 22 and an internal pressure of a portion downstream of the filter 22. Detection signals from these sensors are received by a controller 40 of the exhaust gas control apparatus. This controller 40 performs various controls related to exhaust gas control by driving actuators of the injection valve 12 and the adding valve 20 and the like based on the detection signals from these sensors.
  • the controller 40 executes a burn-off process that burns off particulate matter that is trapped in the filter 22.
  • the particulate matter, trapping performance of the filter 22 is recovered by this burn-off process.
  • fuel is added from the adding valve 20 into the exhaust passage 13.
  • the catalyst bed temperature of the oxidation catalyst 21 is increased to a target temperature, and the filter 22 increases in temperature from the heat of the exhaust gas, thereby causing particulate matter that has accumulated on the filter 22 to be burned off.
  • an accumulation amount of particulate matter ( ⁇ ) on the filter 22 may be obtained by repeating a calculation according to Expression (1) below, for example, at predetermined cycles.
  • ⁇ (i) is the accumulation amount of particulate matter on the filter 22 obtained at the current calculation timing
  • ⁇ (i - 1) is the accumulation amount of particulate matter on the filter 22 obtained at the most recent (i.e., the last) calculation timing
  • PMadd is the amount of particulate matter that has newly accumulated on the filter 22 in a period from the most recent calculation timing until the current calculation timing
  • PMsub is the amount of particulate matter that has been burned off of the filter in the same period.
  • the PMadd and the PMsub are obtained through map calculations using parameter that correlate to the operating state of the engine (i.e., the internal combustion engine). Parameter that correlates to the operating state of the engine (i.e., the internal combustion engine) is a fuel injection quantity, an engine speed, an amount of fuel added by the adding valve 20, the temperature of the filter 22, and the catalyst bed temperature, for example.
  • the execution condition for executing the burn-off process is that at least one of i) the accumulation amount of particulate matter obtained by Expression (1) above is larger than an allowable amount, and ii) the differential pressure detected by the differential pressure sensor 32 is equal to or higher than a predetermined value, be satisfied.
  • the controller 40 controls the manner in which the fuel is added by the adding valve 20, while monitoring the filter temperature and the catalyst bed temperature of the oxidation catalyst 21, such that the catalyst bed temperature of the oxidation catalyst 21 comes to match the target temperature, and the temperature of the filter 22 does not increase too much.
  • the controller 40 makes the catalyst bed temperature of the oxidation catalyst 21 match the target temperature by intermittently adding fuel and adjusting the lengths of an adding period during which time fuel is added, and a pausing period during which time fuel is not added.
  • Sulfur dioxide in the exhaust gas is oxidized when the internal combustion engine is operating.
  • the oxidized sulfur dioxide is adsorbed by the oxidation catalyst 21 in the form of a sulfur oxide, for example, aluminum sulfate such as A12 (S04) 3, and accumulates on the oxidation catalyst 21. Therefore, the controller 40 executes a reduction process that reduces and desorbs sulfur oxide that has accumulated in the oxidation catalyst 21 in this way.
  • the reduction process performed by this exhaust gas control apparatus is executed when the catalyst bed temperature of the oxidation catalyst 21 shifts into a temperature range that is lower than the target temperature of the catalyst bed temperature of the oxidation catalyst 21 in the burn-off process. More specifically, the reduction process is executed under the condition that, with a temperature lower than the target temperature as an upper limit temperature of the temperature range, the catalyst bed temperature of the oxidation catalyst 21 be equal to or lower than this upper limit temperature.
  • this upper limit temperature is a temperature at which sulfur dioxide desorbed from the oxidation catalyst 21 does not reoxidize in the oxidation catalyst 21. That is, when the catalyst bed temperature of the oxidation catalyst 21 is higher than this upper limit temperature, reoxidation of sulfur dioxide does occur frequently in the oxidation catalyst 21. In such a case, the generation of sulfate that causes white smoke such as that described above tends to progress. In contrast, from the viewpoint of the generation of sulfate, when the catalyst bed temperature of the oxidation catalyst 21 is equal to or lower than the upper limit temperature, the reoxidation amount of sulfur dioxide is able to be kept to an extremely small range that is negligible.
  • the controller 40 controls the manner in which the fuel is added by the adding valve 20 such that the catalyst bed temperature of the oxidation catalyst 21 shifts into a temperature range that is equal to or lower than the upper limit temperature, while monitoring the catalyst bed temperature of the oxidation catalyst 21.
  • the controller 40 causes the catalyst bed temperature of the oxidation catalyst 21 to shift into the temperature range that is equal to or lower than the upper limit temperature by adjusting the lengths of the adding period during which time fuel is added and the pausing period during which time fuel is not added. Then the accumulation amount of sulfur oxide in the oxidation catalyst 21 is reduced by this reduction process being performed.
  • an accumulation amount of sulfur oxide ( ⁇ SO) in the oxidation catalyst 21 may be obtained by repeating a calculation according to Expression (2) below, for example, at predetermined cycles.
  • ⁇ SO (i) is the accumulation amount obtained at the current calculation timing
  • ⁇ SO (i - 1) is the accumulation amount obtained at the most recent calculation timing
  • SOadd is the amount of sulfur oxide that has newly accumulated on the oxidation catalyst 21 in a period from the most recent calculation timing until the current calculation timing
  • SOsub is the amount of sulfur oxide that has been reduced and desorbed by the oxidation catalyst 21 in the same period. The SOadd and the SOsub are obtained through map calculations using a parameter that correlates to the concentration of sulfur in the fuel currently being used, in addition to parameter that correlates to the operating state of the engine (i.e., the internal combustion engine).
  • Parameter that correlates to the operating state of the engine is a fuel injection quantity, an engine speed, the amount of fuel added by the adding valve 20, the temperature of the filter 22, and the catalyst bed temperature of the oxidation catalyst 21, for example.
  • step S201 when the execution condition for the burn-off process is satisfied (i.e., YES in step S201), it is then determined whether the catalyst bed temperature of the oxidation catalyst 21 is equal to or lower than the upper limit temperature described above (step S202).
  • step S203 If the catalyst bed temperature of the oxidation catalyst 21 is equal to or lower than the upper limit temperature (i.e., YES in step S202), the reduction process is executed (step S203). Next, the accumulation amount of sulfur oxide in the oxidation catalyst 21 is calculated (step S204). If this accumulation amount is equal to or less than an allowable amount (i.e., YES in step S205), the bum-off process starts (step S206). The bum-off process is continually executed until the accumulation amount of particulate matter on the filter 22 is zero ("0").
  • the allowable amount is a threshold value for limiting the accumulation amount of sulfur oxide while the bum-off process is being executed, so that even if the bum-off process is started and the catalyst bed temperature rises such that sulfur dioxide desorbed from the oxidation catalyst 21 flows into the filter 22 and is reoxidized, it will not affect the generation of white smoke.
  • sulfur oxide that is adsorbed by the oxidation catalyst 21 is reduced by the fuel and desorbed, thus generating sulfur dioxide, and this sulfur dioxide flows into the filter 22 from the oxidation catalyst 21 (amount of sulfur dioxide that flows into a filter from the oxidation catalyst, in FIG. 3).
  • the catalyst bed temperature of the oxidation catalyst 21 is below the upper limit temperature, so reoxidation of the sulfur dioxide in the oxidation catalyst 21 is suppressed.
  • the temperature of the filter 22 is also low, which also suppresses the reoxidation of the sulfur dioxide that has flowed into the filter 22.
  • the accumulation amount of sulfur oxide in the oxidation catalyst 21 gradually decreases (accumulation amount in oxidation catalyst in FIG. 3). Then when the accumulation amount of the sulfur oxide becomes equal to or less than the allowable amount at timing t2, the reduction process ends and the burn-off process begins. As a result, the catalyst bed temperature of the oxidation catalyst 21 rises even higher and gradually converges on a target temperature of the burn-off process (catalyst bed temperature of oxidation catalyst in FIG. 3). In this way, the accumulation amount of sulfur oxide in the oxidation catalyst 21 decreases due to the reduction process that is performed before the burn-off process.
  • the exhaust gas control apparatus described above is able to take the effects described below.
  • the reduction process is executed when the catalyst bed temperature of the oxidation catalyst 21 is lower than the target temperature of the catalyst bed temperature of the oxidation catalyst 21 in the burn-off process. Therefore, the reduction process is able to be performed in an environment in which the catalyst bed temperature of the oxidation catalyst 21 and the filter temperature are low, compared to when the reduction process is performed in conjunction with the burn-off process. Therefore, the generation of sulfate caused by sulfur dioxide being reoxidized in the oxidation catalyst 21 is able to be suppressed. Furthermore, the generation of sulfate caused by sulfur dioxide that has flowed into the filter 22 from the oxidation catalyst 21 being oxidized again in the filter 22 is also able to be suppressed.
  • the timing at which the bum-off process is started is delayed until the accumulation amount of sulfur oxide in the oxidation catalyst 21 becomes equal to or less than the allowable amount through the execution of the reduction process. Therefore, the burn-off process is performed in an environment in which the accumulation amount of sulfur oxide in the oxidation catalyst 21 is low, so the amount of sulfur dioxide that flows into the filter 22 from the oxidation catalyst 21 while the burn-off process is being executed is able to be reduced. Therefore, the generation of sulfate caused by sulfur dioxide being oxidized again in the filter 22 is also able to be suppressed.
  • this exhaust gas control apparatus it is possible to suppress sulfate from being generated from sulfur oxide that has accumulated in the oxidation catalyst, and thereby suppress white smoke from being generated. Also, the reduction process is executed when the catalyst bed temperature of the oxidation catalyst is equal to or less than the upper limit temperature at which sulfur dioxide desorbed from the oxidation catalyst 21 does not reoxidize in the oxidation catalyst 21. Therefore, the reoxidation amount of sulfur dioxide in the oxidation catalyst 21 is able to be suppressed to an extremely small range that is negligible, and as a result, the generation of sulfate when the reduction process is performed is able to be effectively suppressed.
  • the carried amount of the platinum particles per unit volume of the carrier of the filter 22 is made less than the carried amount of platinum particles per unit volume of the carrier of the oxidation catalyst 21. Therefore, the oxidative power of the filter 22 is relatively low, while the oxidative power of the oxidation catalyst 21 is relatively high.
  • the amount of sulfur dioxide adsorbed by the catalyst of the oxidation catalyst 21 increases, and the amount of sulfur dioxide that flows into the filter 22 without being adsorbed by the oxidation catalyst 21 decreases.
  • the generation of sulfate caused by sulfur dioxide flowing into the heated filter 22 is able to be suppressed.
  • the filter 22 even if sulfur dioxide has flowed into the filter 22 from the oxidation catalyst 21, the oxidative power of the filter 22 is low, so reoxidation of the sulfur dioxide is able to be suppressed. Therefore, the amount of sulfate discharged from the filter 22 is able to be further reduced.
  • the carrier of the oxidation catalyst 21 is formed by an alumina-based metal, so sulfur dioxide in the exhaust gas is able to be effectively adsorbed by this carrier. Therefore, it is possible to inhibit sulfur dioxide from flowing into the heated filter 22 from the oxidation catalyst 21 while the burn-off process is being executed, so it is possible to inhibit sulfate from being generated in the filter 22.
  • the timing at which the burn-off process is started is delayed until the accumulation amount of sulfur oxide in the oxidation catalyst 21 becomes equal to or less than the allowable amount.
  • the burn-off process is prohibited when the accumulation amount of sulfur oxide in the oxidation catalyst 21 is larger than the allowable amount.
  • the reduction process is executed in a predetermined environment when the execution condition for the burn-off process is satisfied.
  • the reduction process is executed each time the vehicle runs a predetermined distance.
  • step S401 when the running distance of the vehicle reaches a predetermined distance (i.e., YES in step S401), the running distance is reset to "0" (step S402). Then an executing flag for the reduction process is set to "ON" (step S403), and the process proceeds on to step S404. On the other hand, if the running distance of the vehicle has not reached the predetermined distance (i.e., NO in step S401), the process similarly proceeds on to step S404.
  • a predetermined distance i.e., YES in step S401
  • the predetermined distance is set to a value that is sufficiently shorter than an average distance that the vehicle runs during a period from when the amount of particulate matter that accumulates on the filter 22 is "0" until it reaches an allowable amount.
  • step S404 an accumulation amount of sulfur oxide in the oxidation catalyst 21 is calculated. Then, if this accumulation amount is larger than an allowable amount (i.e., YES in step S405), a prohibiting flag for the burn-off process is set to "ON" (step S406). Next, when the executing flag for the reduction process is "ON" (i.e., YES in step S407), it is then determined whether the catalyst bed temperature of the oxidation catalyst 21 is equal to or less than an upper limit temperature (step S408). When the catalyst bed temperature of the oxidation catalyst 21 is equal to or less than the upper limit temperature (i.e., YES in step S408), the reduction process is executed (step S409).
  • the prohibiting flag for the burn-off process is set to "ON" when the accumulation amount is larger than the allowable amount, and is set to “OFF” when the accumulation amount is equal to or less than the allowable amount.
  • the executing flag for the reduction process is set to "ON” when the running distance of the vehicle reaches a predetermined distance, and is set to "OFF” when the accumulation amount is equal to or less than the allowable amount.
  • step S501 when the execution condition for the burn-off process is satisfied (i.e., YES in step S501), then it is determined whether the prohibiting flag for the burn-off process set in the reduction process before is "OFF" (step S502). When the prohibiting flag is "OFF", the burn-off process starts. Similar to in the first example embodiment, the burn-off process is continually executed until the accumulation amount of the particulate matter on the filter 22 becomes "0".
  • step S501 if the execution condition for the burn-off process is not satisfied (i.e., NO in step S501), or if the prohibiting flag is "ON" (i.e., NO in step S502), this cycle of the routine ends. That is, even if the foregoing execution condition for the bum-off process is satisfied (i.e., YES in step S501), the bum-off process is not executed if the prohibiting flag is "ON" (i.e., NO in step S502). That is, in this exhaust gas control apparatus, the bum-off process is prohibited when the accumulation amount of sulfur oxide in the oxidation catalyst 21 is larger than the allowable amount.
  • the prohibiting flag for the burn-off process is "ON" (prohibiting flag for burn-off process in FIG. 6), so the burn-off process is not executed (execution of burn-off process in FIG 6) even if this execution condition is satisfied. That is, in this example embodiment, as a precondition for executing the burn-off process, at least one of two conditions must be satisfied. These two conditions are i) that the accumulation amount of particulate matter described above be larger than the allowable amount, and ii) that differential pressure detected by the differential pressure sensor 32 be equal to or greater than a predetermined value. In addition to this precondition being satisfied, an essential execution condition for executing the burn-off process is that the prohibiting flag for the burn-off process be "OFF",
  • the accumulation amount of sulfur oxide in the oxidation catalyst 21 gradually decreases (accumulation amount in oxidation catalyst in FIG. 6), and when the accumulation amount becomes equal to or less than the allowable amount at timing t2, the executing flag for the reduction process is set to "OFF" and the reduction process ends. Meanwhile, the prohibiting flag for the burn-off process is set to "OFF" at timing t2. Therefore, the burn-off process is started when the precondition for the bum-off process described above is satisfied.
  • this exhaust gas control apparatus is able to take the effects described below, in addition to the effects of the first example embodiment.
  • the reduction process is executed when the catalyst bed temperature of the oxidation catalyst is equal to or less than the upper limit temperature. Therefore, it may not be possible to ensure sufficient opportunity to execute the reduction process in the first example embodiment in which the reduction process is able to be executed when the execution condition for the burn-off process is satisfied.
  • the reduction process is executed each time the vehicle runs a predetermined distance. Furthermore, this predetermined distance is set to a value that is sufficiently shorter than the average distance that the vehicle runs during a period from when the amount of particulate matter that accumulates on the filter 22 is "0" until it reaches the allowable amount. Therefore, there are a plurality of opportunities for the burn-off process to be executed during the period after the execution condition for the reduction process is no longer satisfied until this execution condition is satisfied. As a result, the number of opportunities to execute the reduction process is able to be increased, so the number of opportunities to execute the burn-off process is also able to be increased.
  • the accumulation amount of sulfur oxide is monitored, and the timing at which the burn-off process is started is delayed until the accumulation amount becomes equal to or less than the allowable amount, when the execution condition for the burn-off process is satisfied.
  • the timing at which the burn-off process is started may also be delayed until the period of time for which or during which the reduction process is executed reaches a predetermined period of time, for example.
  • the timing at which the burn-off process is started may be delayed until the cumulative of this execution period reaches a predetermined period.
  • the timing at which the burn-off process is started may be delayed until a period of time during which the reduction process is continually executed reaches a predetermined period of time.
  • the predetermined period may be changed according to the accumulation amount of sulfur oxide at the time the reduction process started. If the predetermined period of time becomes longer as the accumulation amount becomes larger, the accumulation amount can be appropriately reduced through the reduction process regardless of the accumulation amount of sulfur oxide. Therefore, the burn-off process is able to be performed in an environment in which the accumulation amount of sulfur oxide is small.
  • the amount of sulfur oxide that accumulates in the oxidation catalyst 21 is monitored, but the total amount of sulfur oxide that accumulates on both the oxidation catalyst 21 and the filter 22 may also be monitored, for example.
  • the total amount of sulfur oxide that accumulates on both the oxidation catalyst 21 and the filter 22 may also be monitored, for example.
  • the effect of the example embodiments is able to be taken even when the control of the example embodiments is executed based on this total amount.
  • Fuel is added in the reduction process and the burn-off process using the adding valve 20.
  • fuel may be also be added into the exhaust passage 13 by an injection by the injection valve 12 that is performed during the exhaust stroke (this injection is also referred to as an "after injection”).
  • Fuel can be added by an after injection by the injection valve 12 if the exhaust gas control apparatus is not provided with the adding valve 20.
  • the catalyst bed temperature of the oxidation catalyst and the filter temperature are controlled by adding fuel intermittently, and adjusting the lengths of the adding period during which time fuel is added, and the pausing period during which time fuel is not added, but the manner in which fuel is added is not limited to this.
  • the catalyst bed temperature of the oxidation catalyst and the filter temperature may also be controlled by adjusting the amount of fuel added by the adding valve 20 and adjusting the injection quantity by the injection valve 12 if there is an after injection.
  • an opportunity to execute the reduction process arises each time the running distance of the vehicle reaches the predetermined distance, but an opportunity to execute the reduction process may also be provided each time the cumulative operating time of the internal combustion engine 10 reaches a predetermined time, for example.
  • the reduction process may be executed when the accumulation amount of sulfur oxide in the oxidation catalyst 21 increases to equal to or greater than a predetermined amount (> the allowable amount), or when the catalyst bed temperature of the oxidation catalyst becomes equal to or less than the upper limit temperature.
  • One execution condition of the reduction process is that the catalyst bed temperature of the oxidation catalyst be equal to or lower than the upper limit temperature at which desorbed sulfur dioxide in the oxidation catalyst is not reoxidized.
  • the reduction process may also be executed when the catalyst bed temperature of the oxidation catalyst is higher than the upper limit temperature, if the catalyst bed temperature of the oxidation catalyst is lower than a target temperature of the catalyst bed temperature of the oxidation catalyst in the burn-off process.
  • a carrier on which 3.5 grams of platinum particles (Pt) per 1 liter is carried is employed. This carried amount may be changed appropriately as long as it is equal to or greater than 3.0 grams. Also, in the filter 22, a carrier on which 0.5 grams of platinum particles (Pt) per 1 liter is carried is employed, but this carried amount, may be changed appropriately as long as it is equal to or greater than 1.0 grams. Also, for the filter 22, a carrier on which no platinum particles are carried may also be employed.
  • the carried amount of platinum particles on the carrier of the filter 22 may be equal to or greater than the carried amount in the oxidation catalyst 21.
  • the platinum particles carried on the carrier of the filter 22 may be particles of a platinum-based metal, such as palladium (Pd) or rhodium (Rh).
  • a carrier of an alumina-based metal is employed, but a carrier made from another metal, such as titanium oxide, for example, may also be employed.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Toxicology (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

L'invention concerne un procédé de réduction exécuté lorsque la température d'un lit de catalyseur est inférieure à la température cible du lit de catalyseur dans un procédé de combustion. Lorsqu'une condition d'exécution du procédé de combustion est satisfaite, ce dernier est exécuté, et son exécution est empêchée jusqu'à ce qu'une quantité d'oxyde soufre accumulée dans le catalyseur d'oxydation soit inférieure ou égale à une quantité acceptable via l'exécution du procédé de réduction.
PCT/IB2014/000718 2013-05-14 2014-05-12 Appareil de commande de gaz d'échappement pour moteur à combustion interne WO2014184635A1 (fr)

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JP2013-102454 2013-05-14
JP2013102454A JP2014222062A (ja) 2013-05-14 2013-05-14 内燃機関の排気浄化装置

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113431664A (zh) * 2021-07-21 2021-09-24 广西优艾斯提传感技术有限公司 一种发动机尾气处理系统

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1510679A2 (fr) * 2003-08-29 2005-03-02 Toyota Jidosha Kabushiki Kaisha Méthode et dispositif pour décontaminer un excès de sulfate dans un catalyseur de gaz d'échappement
JP2006291823A (ja) 2005-04-08 2006-10-26 Toyota Motor Corp 内燃機関排気浄化装置
GB2490934A (en) * 2011-05-19 2012-11-21 Gm Global Tech Operations Inc Method of desulphurisation of a Lean NOx Trap
WO2013014514A2 (fr) * 2011-07-27 2013-01-31 Toyota Jidosha Kabushiki Kaisha Appareil de commande des gaz d'échappement pour moteur à combustion interne et procédé de commande pour appareil de commande des gaz d'échappement pour moteur à combustion interne

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4094966B2 (ja) * 2003-02-03 2008-06-04 日野自動車株式会社 排気浄化装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1510679A2 (fr) * 2003-08-29 2005-03-02 Toyota Jidosha Kabushiki Kaisha Méthode et dispositif pour décontaminer un excès de sulfate dans un catalyseur de gaz d'échappement
JP2006291823A (ja) 2005-04-08 2006-10-26 Toyota Motor Corp 内燃機関排気浄化装置
GB2490934A (en) * 2011-05-19 2012-11-21 Gm Global Tech Operations Inc Method of desulphurisation of a Lean NOx Trap
WO2013014514A2 (fr) * 2011-07-27 2013-01-31 Toyota Jidosha Kabushiki Kaisha Appareil de commande des gaz d'échappement pour moteur à combustion interne et procédé de commande pour appareil de commande des gaz d'échappement pour moteur à combustion interne

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113431664A (zh) * 2021-07-21 2021-09-24 广西优艾斯提传感技术有限公司 一种发动机尾气处理系统

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