WO2013153610A1 - Dispositif de commande pour moteur à combustion interne - Google Patents

Dispositif de commande pour moteur à combustion interne Download PDF

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Publication number
WO2013153610A1
WO2013153610A1 PCT/JP2012/059724 JP2012059724W WO2013153610A1 WO 2013153610 A1 WO2013153610 A1 WO 2013153610A1 JP 2012059724 W JP2012059724 W JP 2012059724W WO 2013153610 A1 WO2013153610 A1 WO 2013153610A1
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Prior art keywords
catalyst
amount
air
fuel ratio
hydrogen
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PCT/JP2012/059724
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English (en)
Japanese (ja)
Inventor
岡崎　俊太郎
中川　徳久
雄士 山口
藤原　孝彦
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トヨタ自動車株式会社
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Priority to PCT/JP2012/059724 priority Critical patent/WO2013153610A1/fr
Publication of WO2013153610A1 publication Critical patent/WO2013153610A1/fr

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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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/008—Controlling each cylinder individually
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/085—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
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
    • F01N3/0885—Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/0223—Variable control of the intake valves only
    • F02D13/0234—Variable control of the intake valves only changing the valve timing only
    • F02D13/0238—Variable control of the intake valves only changing the valve timing only by shifting the phase, i.e. the opening periods of the valves are constant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
    • F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0002—Controlling intake air
    • F02D2041/001—Controlling intake air for engines with variable valve actuation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • 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

Definitions

  • the present invention relates to a technical field of a control device for an internal combustion engine suitable for recovering an exhaust purification catalyst installed in an exhaust path from sulfur poisoning.
  • the exhaust purification catalyst installed in the exhaust path adsorbs sulfur contained as impurities in the fuel to the noble metal added to the catalyst and poisons the sulfur.
  • sulfur poisoning the activity of the catalyst is remarkably lost, and the original exhaust purification action of the catalyst cannot be obtained. Therefore, various sulfur poisoning recovery controls have been proposed for desorbing sulfur from the catalyst. Yes.
  • sulfur is oxidized inside the cylinder or in the exhaust path and is adsorbed to the catalyst as SOx (sulfur oxide), and the desorption of sulfur simply means reduction of sulfur.
  • Patent Document 1 discloses sulfur poisoning recovery control in a lean NOx catalyst.
  • the exhaust gas purification apparatus for an internal combustion engine disclosed in Patent Document 1 includes an H 2 (hydrogen) sensor upstream of the lean NOx catalyst, and rich combustion in the cylinder is controlled based on the output value of the H 2 sensor. It is the composition which becomes. That is, it is configured that the H 2 concentration of the catalyst inflow gas is F / B controlled to a rich combustion control amount, and an appropriate amount of hydrogen can be supplied at the time of sulfur poisoning recovery.
  • H 2 hydrogen
  • Patent Document 2 discloses a technique for raising the temperature of the catalyst by controlling some cylinders to be rich in the air-fuel ratio and the remaining cylinders to be air-fuel ratio lean.
  • Patent Document 3 discloses a configuration in which H 2 is supplied by an H 2 supply means mounted upstream of the catalyst when the amount of sulfur accumulated in the NOx catalyst exceeds a predetermined value.
  • Patent Document 4 a CO 2 adsorbent, an H 2 generation catalyst, and a NOx catalyst are arranged in an exhaust system of a lean combustion engine, and CO is supplied to the H 2 generation catalyst, which is generated by an aquatic gas shift reaction.
  • a configuration in which H 2 is sent as a reducing agent to the NOx catalyst is disclosed.
  • Patent Document 5 discloses a lean NOx catalyst system, and in an internal combustion engine capable of controlling in-cylinder combustion, when NOx catalyst is regenerated, post-injection timing is performed at a timing when the dehydrogenation reaction and cracking reaction repel each other.
  • the structure to perform is disclosed.
  • Patent Document 1 does not mention anything about this point.
  • combustion on the rich side of the air-fuel ratio is a disadvantageous control from the viewpoint of exhaust emission, apart from the reduction of sulfur and NOx, and is also economically disadvantageous in that it leads to a deterioration in fuel consumption. Control. Therefore, it is not reasonable to perform rich combustion in the dark cloud on the safe side (in this case, that is, on the side where the amount of hydrogen generated increases) for the purpose of reducing only sulfur.
  • the present invention has been made in view of the above-described circumstances, and provides an internal combustion engine control device capable of recovering a catalyst from sulfur poisoning while suppressing an increase in cost and deterioration of exhaust emission and fuel consumption. This is the issue.
  • an internal combustion engine control apparatus controls an internal combustion engine including a plurality of cylinders and an exhaust purification catalyst installed in an exhaust path connected to the plurality of cylinders.
  • a control unit for an internal combustion engine that determines whether or not to perform sulfur poisoning recovery of the catalyst; and exhaust gas that flows into the catalyst when it is determined to perform sulfur poisoning recovery.
  • Poisoning recovery control means for controlling the air-fuel ratio of the plurality of cylinders, wherein the poisoning recovery control means controls the degree of imbalance of the air-fuel ratio among the plurality of cylinders (first item) ).
  • the internal combustion engine according to the present invention is a concept encompassing an engine that can convert thermal energy generated when an air-fuel mixture containing fuel burns into kinetic energy and take it out.
  • the number of cylinders, the cylinder arrangement, the fuel type, the fuel injection mode, the intake / exhaust system configuration, the valve train configuration, the combustion system, the presence / absence of the supercharger, and the excess is not limited in any way.
  • the exhaust purification catalyst according to the present invention is a concept encompassing various types of catalysts that can be provided in the exhaust path of an internal combustion engine.
  • a three-way catalyst for example, a lean NOx catalyst (also referred to as a NOx storage reduction catalyst).
  • Practical forms such as oxidation catalyst.
  • the catalyst is poisoned by sulfur contained as an impurity in the fuel according to the actual operation period of the internal combustion engine. Since sulfur poisoning of the catalyst reduces the catalytic activity, it is necessary to desorb sulfur from the catalyst at the appropriate timing (that is, to recover the catalyst from sulfur poisoning). In the control apparatus for an internal combustion engine according to the present invention, it is determined by the determining means whether or not to perform sulfur poisoning recovery. “Sulfur poisoning recovery” is a concept encompassing control, processing and measures for recovering the catalyst from the sulfur poisoning state.
  • the criteria for determining whether or not the determination means implements sulfur poisoning recovery is ambiguous. For example, in practice, it is effective to perform sulfur poisoning recovery at a timing at which the degree of sulfur poisoning can be considered to have exceeded a predetermined level, but the timing at which sulfur poisoning recovery measures are taken is not limited to this. . That is, the determination means may determine that the sulfur poisoning recovery is performed when the elapsed time after the internal combustion engine has been operated exceeds a predetermined value, or more fluidly, the internal combustion engine is stationary. It may be determined that the sulfur poisoning recovery is performed at an appropriate timing in the operating state. That is, the recovery from sulfur poisoning is effective regardless of the level of sulfur poisoning of the catalyst.
  • the control apparatus for an internal combustion engine controls the air-fuel ratio of the exhaust gas flowing into the catalyst (hereinafter referred to as “catalyst inflow gas” as appropriate) by the poisoning recovery control means. More specifically, the poisoning recovery control means is configured to control the degree of air-fuel ratio imbalance among a plurality of cylinders.
  • the imbalance as the degree of imbalance Depending on the degree, the amount of hydrogen produced in the cylinder can be controlled.
  • the average air fuel ratio of all the cylinders in one cycle is always desired value (for example, theoretical air fuel ratio equivalent value). ) Can be maintained. That is, although it is necessary to individually control the air-fuel ratio for each cylinder, it is possible to supply hydrogen to the catalyst without apparently changing the air-fuel ratio of the catalyst inflow gas from when sulfur poisoning recovery is not performed. . Therefore, drivability and power performance deterioration due to torque fluctuation, and emission and fuel consumption deterioration can be suitably suppressed.
  • the control device for an internal combustion engine according to the present invention has a great practical advantage in that an increase in cost can be avoided.
  • air-fuel ratio imbalance in the present invention is a quantitative index that means the degree of air-fuel ratio imbalance among a plurality of cylinders, and its practical aspect is within the scope of the concept. Ambiguous. Further, the degree of imbalance of the air-fuel ratio may be a value determined for the internal combustion engine or a value determined for each cylinder according to a practical definition.
  • the “degree of air-fuel ratio imbalance” may include, for example, those defined in (1) to (4) below.
  • the “corresponding value” below is a concept that includes a control amount, a physical amount, or an index value that can have a unique relationship with the target value.
  • a value corresponding to the ratio of the air-fuel ratio of each cylinder to the average value of the air-fuel ratio of all cylinders (2) A value corresponding to the ratio of the air-fuel ratio of a specific cylinder to the air-fuel ratio of the remaining cylinders (3) Target A value corresponding to the ratio of the deviation between the target air-fuel ratio and the air-fuel ratio of each cylinder with respect to the air-fuel ratio (4) A value corresponding to the ratio of the air-fuel ratio of each cylinder with respect to the target air-fuel ratio It is desirable that the air-fuel ratio rich side cylinder and the air-fuel ratio lean side cylinder are not fixed.
  • the deviation between the cylinders in the average air-fuel ratio of a cylinder should be small within one sulfur poisoning recovery cycle or between a plurality of sulfur poisoning recovery cycles. This is because if the cylinder on the air-fuel ratio rich side is always fixed, the in-cylinder state of each cylinder may vary every time the sulfur poisoning recovery is repeated.
  • control apparatus further includes an accumulation amount estimation unit that estimates an accumulation amount of sulfur in the catalyst, and the determination unit is configured to determine the sulfur based on the estimated accumulation amount. It is determined whether or not poisoning recovery is carried out (2nd term).
  • the accumulated amount estimating means estimates the accumulated amount of sulfur in the catalyst, and the estimated accumulated amount is used to determine whether or not the sulfur poisoning recovery is performed by the determining means. Therefore, the catalyst can be accurately recovered from the sulfur poisoning at a stage where the sulfur poisoning to some extent is efficient.
  • the “accumulation amount” estimated by the accumulation amount estimation means includes physical accumulation amount, adhesion amount, adsorption amount accompanied by chemical adsorption process, etc., and sulfur poisoning process (depending on the catalyst).
  • the expressions may vary.
  • the accumulated amount is an experimental value in advance of an internal combustion engine operating parameter that may include at least part of the engine speed, intake pressure, accelerator opening, intake air amount, throttle opening, load factor, and fuel injection amount. It may be estimated based on the correlation between the operating parameter and the amount of sulfur production, which is established empirically or theoretically.
  • the amount of sulfur or sulfur oxide (SOx) discharged per unit time in the exhaust path of the internal combustion engine may be integrated, and the accumulated amount may be estimated from this integrated value.
  • the relationship between the integrated value and the actual accumulated amount is clear (that is, not all sulfur or sulfur oxide discharged from the cylinder is deposited on the catalyst), the relationship is further referred to. May be.
  • control device further includes in-catalyst production amount estimation means for estimating a production amount of hydrogen in the catalyst, and the determination means generates hydrogen in the estimated catalyst. It is determined whether or not the sulfur poisoning recovery is performed based on the amount (Section 3).
  • the control device for an internal combustion engine has a technical idea of recovering from sulfur poisoning by supplying hydrogen generated in the cylinder to the catalyst. However, depending on the configuration and type of the catalyst, It is also produced in the catalyst. Since hydrogen produced by the catalyst and hydrogen produced inside the cylinder are not distinguished from the viewpoint of recovering sulfur from poisoning, in determining whether to perform sulfur poisoning recovery, It is desirable to consider the amount of hydrogen produced. According to this aspect, the amount of hydrogen produced in the catalyst is estimated by the in-catalyst generation amount estimation means, and this estimation result is taken into account when the determination means determines whether or not to perform sulfur poisoning recovery.
  • the hydrogen generated in the cylinder is reduced. It is possible to appropriately determine that the used sulfur poisoning recovery is unnecessary.
  • hydrogen generated in the catalyst cannot be fully used for recovery of sulfur poisoning, so that sulfur poisoning recovery using hydrogen generated in the cylinder is more effective. A determination that it is necessary can be made as appropriate. Therefore, the execution timing, the execution frequency, and the implementation scale of the sulfur poisoning recovery by the sulfur poisoning recovery control means can be more optimally maintained according to the actual situation.
  • the amount of hydrogen produced in the catalyst can be determined in advance, for example, experimentally, empirically, or theoretically, using various operating conditions of the internal combustion engine as parameters. It can be made available as data on the map. Alternatively, the hydrogen generation process in the catalyst is converted into an arithmetic algorithm, the instantaneous hydrogen generation amount is obtained based on the operating conditions of the internal combustion engine at that time, and the instantaneous generation amount is integrated for a predetermined period, thereby The amount of hydrogen generation may be estimated.
  • the in-catalyst production amount estimation means may estimate the production amount of hydrogen by the water gas shift reaction and the steam reforming reaction as the production amount of hydrogen in the catalyst.
  • the amount of hydrogen produced in the catalyst varies depending on the type of catalyst, but basically varies depending on the catalyst bed temperature.
  • the water temperature shift reaction CO + H 2 O ⁇ H 2 + CO 2
  • the steam reforming reaction on the high temperature side with a temperature range of about 600 to 700 ° C. as a boundary.
  • hydrogen is generated by (HC + H 2 O ⁇ H 2 + CO). Therefore, according to this aspect, the amount of hydrogen produced in the catalyst is required and can be estimated with sufficient accuracy.
  • an arithmetic expression, a control map, and the like are prepared in advance for associating the hydrogen generation amount or hydrogen concentration by the reaction with the catalyst bed temperature. Also good.
  • an accumulation amount estimation means for estimating an accumulation amount of sulfur in the catalyst and an in-catalyst production amount estimation means for estimating an amount of hydrogen generation in the catalyst.
  • the determination means determines whether or not to perform the sulfur poisoning recovery based on the estimated sulfur accumulation amount in the catalyst and the estimated hydrogen generation amount in the catalyst (Section 5). ).
  • the sulfur accumulation amount estimated by the accumulation amount estimation means equivalent to that described above, and the hydrogen production amount estimated by the in-catalyst production amount estimation means equivalent to those described above Based on the above, it is determined whether or not to perform sulfur poisoning recovery. For example, when the reaction amount of sulfur is calculated from the estimated amount of hydrogen generated in the catalyst, and the difference value obtained by subtracting the calculated reaction amount from the estimated amount of accumulated sulfur is a predetermined value or more, etc. A decision is made to implement sulfur poisoning recovery.
  • an accumulation amount estimation means for estimating the amount of sulfur accumulation in the catalyst an in-catalyst production amount estimation means for estimating the amount of hydrogen production in the catalyst, Based on the estimated amount of accumulated sulfur and the estimated amount of hydrogen generated in the catalyst, the required amount estimating means for estimating the required amount of hydrogen in the cylinder, and in the cylinder by controlling the degree of imbalance
  • An in-cylinder generation amount estimation means for estimating the amount of hydrogen generation, and the poisoning recovery control means is based on the estimated hydrogen generation amount in the cylinder so as to obtain the estimated required amount.
  • the degree of imbalance is controlled (sixth term).
  • the control of the air-fuel ratio imbalance degree by the poisoning recovery control means is the combustion state of the individual cylinders. Realized by deviating from the ideal combustion state. Therefore, it is desirable that the amount of hydrogen generated inside the cylinder for recovering the catalyst from sulfur poisoning is an amount necessary and sufficient to recover the sulfur poisoning of the catalyst.
  • the request amount estimation unit determines the hydrogen content in the cylinder. Estimate the required amount.
  • the required amount is a concept including a concentration defined as weight or volume per unit time or unit volume in addition to typical quantitative indicators such as weight and volume.
  • the required amount estimating means subtracts the amount of hydrogen generated in the catalyst estimated by the in-catalyst generation amount estimating means from the accumulated amount estimated by the accumulated amount estimating means, and determines the degree of imbalance by the poisoning recovery control means.
  • the required amount of hydrogen to be generated by control may be estimated.
  • the required amount estimation means for example, corrects the accumulation amount estimated by the accumulation amount estimation means to the subtraction side according to the hydrogen production amount in the catalyst estimated by the in-catalyst production amount estimation means, etc.
  • the required amount may be estimated.
  • the in-cylinder generation amount estimation means estimates the amount of hydrogen generated in the cylinder by controlling the degree of imbalance.
  • the amount of hydrogen generated in the cylinder is a concept including a concentration defined as a unit time or a weight or volume per unit volume, in addition to a typical quantitative index such as weight or volume. .
  • the control device for an internal combustion engine according to the present invention employs a configuration in which the amount of hydrogen produced in the cylinder is controlled by controlling the degree of imbalance, so that the degree of imbalance and the amount of hydrogen produced in the cylinder or the amount of hydrogen produced
  • the relationship with the hydrogen concentration according to is given experimentally, empirically or theoretically in advance.
  • the estimated amount of hydrogen generated in the cylinder is determined so that the estimated recovery amount is obtained by the poisoning recovery control means.
  • the degree of imbalance is controlled based on this.
  • the practical control mode of the imbalance degree may be various.
  • the sulfur poisoning recovery time may be determined from the estimated hydrogen generation amount in the cylinder.
  • the target value of the imbalance degree is set so that the catalyst recovers from sulfur poisoning within the period. May be determined.
  • the amount of hydrogen generated in the cylinder by the poisoning recovery control means can always be optimized according to the degree of sulfur poisoning of the catalyst, and the increase in cost and the deterioration of emission and fuel consumption are suppressed.
  • the catalyst can be recovered from sulfur poisoning. For example, if the required amount of hydrogen in the cylinder is estimated according to only the amount of sulfur accumulated in the catalyst, the amount of hydrogen supplied to the catalyst becomes excessive by the amount of hydrogen produced in the catalyst. In other words, the amount of hydrogen supplied to the catalyst is larger than necessary and sufficient, and the time for the combustion state of the internal combustion engine to deviate from the ideal combustion state becomes unnecessarily long, and exhaust emissions and fuel consumption deteriorate. Turn into. In this aspect, such a situation is avoided.
  • the in-catalyst generation amount estimation means may estimate the amount of hydrogen generation in the catalyst based on the temperature of the catalyst that changes due to the control of the imbalance degree (Seventh Item). .
  • the catalyst bed temperature is related to the amount of hydrogen produced in the catalyst, and the relationship can be determined experimentally, empirically or theoretically in advance.
  • the in-catalyst generation amount estimation means estimates the hydrogen generation amount in the catalyst in consideration of such an action of increasing the catalyst bed temperature.
  • the configuration for estimating the hydrogen production amount in the catalyst from the result of the imbalance is a kind of circulation reference. At first glance it lacks logical consistency.
  • the imbalance control by the poisoning recovery control means is preferably continued until the sulfur accumulation amount is sufficiently reduced with reference to the sulfur accumulation amount of the catalyst that changes in real time. In calculating the remaining amount, it is practically possible to reflect the influence of the catalyst bed temperature changed by controlling the imbalance degree.
  • a target value of the catalyst bed temperature suitable for sulfur poisoning recovery is determined, and the degree of imbalance is controlled so that the catalyst bed temperature can be maintained at the target value.
  • the sulfur poisoning recovery may be performed for an optimal time considering the amount of hydrogen produced in
  • the target value of the imbalance degree may be determined in consideration of a change in the amount of hydrogen generated in the catalyst due to an increase in the catalyst bed temperature, and the poisoning recovery control means may control the imbalance degree.
  • the internal combustion engine includes first detection means for detecting an air-fuel ratio equivalent value of exhaust flowing into the catalyst, and an air-fuel ratio of exhaust discharged from the catalyst. And a second detecting means for detecting an equivalent value, wherein the control device for the internal combustion engine includes an air-fuel ratio equivalent value of the exhaust gas flowing into the detected catalyst and an empty air exhausted from the detected catalyst.
  • Air-fuel ratio control means for converging the air-fuel ratio inside the catalyst to the target air-fuel ratio based on the fuel-equivalent value is further provided (Section 8).
  • the first detection means capable of detecting the air-fuel ratio equivalent value of the catalyst inflow gas and the air-fuel ratio equivalent of the exhaust gas discharged from the catalyst (hereinafter referred to as “catalyst exhaust gas” as appropriate).
  • Second detection means capable of detecting a value.
  • the “air-fuel ratio equivalent value” may be a value whose behavior has a unique relationship with the air-fuel ratio, such as an oxygen concentration in addition to the air-fuel ratio itself. These may be detected as a voltage value that can be converted into an air-fuel ratio through a predetermined conversion process using, for example, an arithmetic expression or a map.
  • the air-fuel ratio of the catalyst inflow gas and the air-fuel ratio of the catalyst exhaust gas preferably mean time average values of the air-fuel ratio of these gases.
  • the air-fuel ratio control means converges the air-fuel ratio inside the catalyst to the target air-fuel ratio based on the air-fuel ratio equivalent values of the catalyst inflow gas and the catalyst exhaust gas.
  • air-fuel ratio F / B control such control of the air-fuel ratio control means is appropriately expressed as “air-fuel ratio F / B control”.
  • the fuel injection amount of each cylinder is appropriately corrected from the reference fuel injection amount so that the air-fuel ratio inside the catalyst becomes the target air-fuel ratio, but its practical aspect is ambiguous. Is.
  • the air-fuel ratio F / B may be constructed from sub F / B control using the second detection means and main F / B control using the first detection means. More specifically, in the sub F / B control, the air-fuel ratio of the catalyst exhaust gas is set to the target air according to the deviation between the air-fuel ratio detected directly or indirectly by the second detecting means and the target air-fuel ratio.
  • the sub-F / B control amount for converging to the fuel ratio is calculated, and the air-fuel ratio or its target air-fuel ratio detected directly or indirectly by the first detection means based on the sub-F / B control amount It may be constructed as a control for correcting.
  • the catalyst inflow is determined according to the deviation between the corrected air-fuel ratio and the target air-fuel ratio, or according to the deviation between the detected air-fuel ratio and the corrected target air-fuel ratio.
  • the main F / B control amount (for example, a correction coefficient to be multiplied by the reference injection amount) for converging the gas air-fuel ratio to the target air-fuel ratio is determined, and the control may be constructed to correct the reference injection amount.
  • the air-fuel ratio F / B control in the present application may be so-called PI control in which the F / B control amount includes a proportional term (P term) and an integral term (I term), or the F / B control amount, for example. May be so-called PID control constructed by adding a differential term (D term) to the proportional term and the integral term. Further, the air-fuel ratio F / B control may be performed uniformly for all cylinders or may be performed individually for each cylinder.
  • the air-fuel ratio inside the catalyst can be maintained at the target air-fuel ratio, so the degree of imbalance of the air-fuel ratio between the cylinders is changed in order to recover the catalyst from sulfur poisoning. In doing so, the influence on the air-fuel ratio of the entire engine can be reduced. Accordingly, it is possible to suitably suppress the deterioration of exhaust emission and fuel consumption.
  • the poisoning recovery control means includes a variable valve operating device capable of changing an opening / closing timing of at least one of a fuel injection device, an intake valve, and an exhaust valve, and Control at least one of the EGR devices (Section 9).
  • the air-fuel ratio imbalance occurs when the balance between the amount of air sucked into the cylinder and the amount of fuel supplied into the cylinder differs between the cylinders. Therefore, one of the most appropriate control targets for controlling the degree of air-fuel ratio imbalance is a fuel injection device capable of changing the fuel injection amount for each cylinder.
  • the intake air is different for each cylinder.
  • the amount can be changed. Therefore, hydrogen can be generated in the cylinder.
  • the intake throttle valve is independent for each cylinder, the intake air amount can be made different for each cylinder.
  • EGR exhaust Gas Recirculation
  • the ratio of fresh air to the gas sucked into the cylinder and the homogeneity of the formed air-fuel mixture can be changed.
  • the configuration is such that EGR can be introduced independently for each cylinder (for example, a configuration in which each cylinder has an EGR pipe and an EGR valve, respectively), the intake air amount can be made different for each cylinder. And an air-fuel ratio imbalance can be realized.
  • the poisoning recovery control means may further control the ignition device in addition to the device capable of changing the air-fuel ratio imbalance.
  • the ignition timing When the ignition timing is changed to the retarded angle side, the progress of the combustion reaction in the cylinder generally shifts to the retarded angle side. For this reason, it is possible to continue the combustion reaction when the exhaust valve is opened, and it is possible to increase the temperature of the exhaust path and the catalyst communicating therewith.
  • the catalyst bed temperature affects the amount of hydrogen produced in the catalyst and the desorption of sulfur in the catalyst. Therefore, it is possible to independently control the amount of hydrogen generated in the cylinder by the imbalance degree and the catalyst bed temperature through the control of the ignition timing. In this case, the imbalance degree can be controlled without considering the influence on the catalyst bed temperature, and a higher degree of freedom can be given by the control range of the imbalance degree.
  • the internal combustion engine has an internal combustion engine that uses gasoline as a fuel, a compression auto-ignition internal combustion engine that uses light oil as a fuel, or an air-fuel ratio due to stratified combustion.
  • a combustion lean combustion internal combustion engine maintained at a lean air-fuel ratio (Section 10).
  • the configuration of the catalyst or the catalyst system also changes. However, for example, whether it is a three-way catalyst or a lean NOx catalyst, the problem of sulfur poisoning can also occur.
  • the control device for an internal combustion engine according to the present invention can be applied regardless of the configuration of the internal combustion engine.
  • Compressed self-ignition internal combustion engines are mainly concerned with whether or not fresh air is sufficient for the amount of fuel, and the combustion state is controlled not by air-fuel ratio control but by injection amount control.
  • the combustion state is controlled not by air-fuel ratio control but by injection amount control.
  • 1 is a schematic configuration diagram conceptually showing a configuration of an engine system according to an embodiment of the present invention.
  • 2 is a flowchart of sulfur poisoning recovery control executed by an ECU in the engine system of FIG. 1. It is a conceptual diagram of the 1st hydrogen concentration map referred in the sulfur poisoning recovery control of FIG. It is a conceptual diagram of the 2nd hydrogen concentration map referred in the sulfur poisoning recovery control of FIG. It is a flowchart of the sulfur poisoning recovery control which concerns on 2nd Embodiment of this invention.
  • FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10.
  • an engine system 10 is mounted on a vehicle (not shown) and includes an ECU 100 and an engine 200.
  • the ECU 100 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like and is configured to be able to control the operation of the engine system 10, and is an example of the “control device for an internal combustion engine” according to the present invention.
  • the ECU 100 is configured to be able to execute sulfur poisoning recovery control, which will be described later, according to a control program stored in the ROM.
  • the ECU 100 includes the “determination unit”, “accumulated amount estimation unit”, “in-catalyst generation amount estimation unit”, “in-cylinder generation amount estimation unit”, “request amount estimation unit”, “poisoning recovery” according to the present invention. It is an integrated electronic control unit that can function as an example of each of “control means” and “air-fuel ratio control means”, but the physical, mechanical, and electrical configurations of these means according to the present invention are limited to this. Instead, these means may be configured as various computer systems such as a plurality of ECUs, various processing units, various controllers, or a microcomputer device.
  • Engine 200 is a multi-cylinder gasoline engine that is an example of an “internal combustion engine” according to the present invention.
  • the engine 200 includes a plurality of cylinders 201 accommodated in a cylinder block CB.
  • the cylinders 201 are arranged in the depth direction of the drawing, and only one cylinder 201 is shown in FIG. 1.
  • the combustion chamber formed in the cylinder 201 is provided with a piston 202 that reciprocates in the vertical direction in the figure in accordance with the explosive force accompanying the combustion of the air-fuel mixture.
  • the reciprocating motion of the piston 202 is converted into the rotational motion of the crankshaft 204 via the connecting rod 203 and is used as power for the vehicle on which the engine 200 is mounted.
  • crank position sensor 205 capable of detecting the rotational position (ie, crank angle) of the crankshaft 204 is installed.
  • the crank position sensor 205 is electrically connected to the ECU 100, and the detected crank angle is referred to the ECU 100 at a constant or indefinite period.
  • the crank position sensor 205 is used for calculation of the engine speed NE or other control. It becomes the composition which is done.
  • air sucked from the outside is purified by a cleaner (not shown) and then guided to a common intake pipe 206 for each cylinder.
  • the intake pipe 206 is provided with a throttle valve 207 that can adjust the amount of intake air that is the amount of intake air.
  • the throttle valve 207 is configured as a kind of electronically controlled throttle valve whose driving state is controlled by a throttle valve motor (not shown) electrically connected to the ECU 100.
  • the ECU 100 basically drives and controls the throttle valve motor so as to obtain a throttle opening corresponding to an accelerator opening Ta detected by an unillustrated accelerator position sensor. However, the ECU 100 can also adjust the throttle opening without intervention of the driver's intention through the operation control of the throttle valve motor.
  • the intake air appropriately adjusted by the throttle valve 207 is sucked into the cylinder through the intake port 208 corresponding to each cylinder 201 when the intake valve 209 is opened.
  • the intake valve 209 is configured such that its opening / closing timing is defined according to the cam profile of a cam 210 having a substantially elliptical shape in cross section as shown in the figure.
  • the cam 210 is fixed to an intake camshaft (reference number omitted) connected to the crankshaft 204 via power transmission means such as a cam sprocket or a timing chain. Therefore, the opening / closing phase of the intake valve 209 is uniquely related to the rotation phase of the crankshaft 204 (ie, the crank angle) in one fixed state.
  • the fixed state between the intake cam 210 and the intake camshaft varies depending on the hydraulic pressure of the control oil supplied by the hydraulic drive device 211.
  • the intake cam 210 is connected to the intake cam shaft via a wing-like member called a vane, and the rotational phase between the vane and the intake cam shaft is applied to the hydraulic chamber of the hydraulic drive device 211.
  • the configuration changes according to the hydraulic pressure applied. Therefore, the rotational phase between the intake cam 210 fixed to the vane and the intake camshaft also changes according to the hydraulic pressure.
  • the hydraulic drive device 211 is in a state of being electrically connected to the ECU 100, and the ECU 100 can change the opening / closing timing of the intake valve 209 independently for each cylinder through the control of the hydraulic drive device 211. That is, the hydraulic drive device 211 is an example of a configuration that can be adopted by the “variable valve operating device” according to the present invention.
  • variable valve apparatus which concerns on this invention can take is not limited to the thing of this embodiment.
  • the intake valve 209 may be a so-called electromagnetically driven valve (cam-by-wire) that is electromagnetically driven by a solenoid actuator or the like.
  • the intake air guided to the intake port 208 is mixed with the fuel (gasoline) injected from the intake port injector 212 in which a part of the injection valve is exposed at the intake port 208 to become the above-described mixture.
  • Gasoline as fuel is stored in a fuel tank (not shown), and is supplied to the intake port injector 212 via a delivery pipe (not shown) by the action of a low-pressure feed pump (not shown).
  • a drive device (not shown) that drives the injection valve is electrically connected to the ECU 100, and the intake port injector 212 controls the valve opening period of the injection valve via the drive device. By doing so, an amount of fuel spray corresponding to this valve opening period can be supplied to the intake port 208.
  • the intake port injector 212 is an example embodiment that corresponds to the “fuel injection device” according to the present invention.
  • a part of a spark plug (not shown) of an ignition device 213 that is a spark ignition device is exposed.
  • the air-fuel mixture compressed in the compression stroke of the engine 200 is ignited and burned by the ignition operation of the spark plug.
  • the ignition device 213 is electrically connected to the ECU 100, and the ignition timing of the ignition device 213 is controlled by the ECU 100.
  • the air-fuel mixture that has undergone a combustion reaction in the combustion chamber is opened and closed by an exhaust valve 215 that is driven to open and close by the cam profile of the exhaust cam 214 that is indirectly connected to the crankshaft 204 in the exhaust stroke following the combustion stroke.
  • the exhaust port 216 is discharged.
  • the exhaust port 216 is connected to an exhaust manifold (not shown in FIG. 1 because of its cross-sectional view) on the downstream side (side away from the cylinder 201).
  • the exhaust manifold is a device that guides the exhaust discharged from the exhaust port 216 to the exhaust pipe 219 after collecting all the cylinders, and is connected to the exhaust pipe 219.
  • EGR pipe 217 One end of an EGR pipe 217 is connected to the exhaust manifold connected to the exhaust port 216.
  • the other end of the EGR pipe 217 is connected to an intake manifold (reference numeral omitted) located on the upstream side of the intake port 208, and a part of the exhaust can be returned to the intake system as EGR gas.
  • the EGR amount that is the supply amount of EGR gas is controlled by an EGR valve 218 installed in the EGR pipe 217.
  • the EGR valve 218 is an electromagnetically driven valve that controls the opening and closing of the valve by the electromagnetic force of the solenoid, and the valve opening degree is controlled by the control of the ECU 100 electrically connected to the drive device that controls the excitation state of the solenoid. It becomes the composition which is done.
  • the EGR pipe 217 is connected to the exhaust manifold connected to the exhaust port 216.
  • the EGR pipe 217 may be connected to the exhaust pipe 219 connected to the exhaust manifold.
  • the EGR pipe 217 is connected to the exhaust system on the upstream side (cylinder side) from the three-way catalyst 220 described later, and the EGR pipe 217 and the EGR valve 218 provide the “EGR” according to the present invention.
  • An HPL (High Pressure Loop) EGR device which is an example of the “device”, is configured.
  • the configuration of the EGR device is not limited to this.
  • the EGR device may be an LPL (Low Pressure-Loop) EGR device in which the EGR pipe 217 is connected to the downstream side of a three-way catalyst 220 described later in the exhaust pipe 219 and takes out exhaust gas after passing through the three-way catalyst.
  • the exhaust pipe 219 is connected to the exhaust port 216 of each cylinder.
  • the exhaust pipe 214 is an example of an “exhaust path” according to the present invention.
  • the exhaust pipe 219 is provided with a three-way catalyst 220 as an example of the “exhaust purification catalyst” according to the present invention.
  • the three-way catalyst 215 is a known catalyst device in which a noble metal such as platinum is supported on a catalyst carrier.
  • the three-way catalyst 215 emits exhaust gas by causing the oxidative combustion reaction of HC and CO and the reduction reaction of nitrogen oxide NOx to proceed substantially simultaneously. It can be purified. Note that when the three-way catalyst 220 is installed in the exhaust pipe 219 connected to the exhaust manifold, the exhaust gas flowing into the three-way catalyst 220 in this embodiment is the exhaust after being aggregated for all the cylinders of the engine 200. is there.
  • the input side air-fuel ratio A / Fin that is the air-fuel ratio of the catalyst inflow gas (exhaust after being aggregated for all cylinders) flowing into the three-way catalyst 220 can be detected.
  • An air-fuel ratio sensor 221 is installed.
  • the air-fuel ratio sensor 221 is, for example, a limiting current type wide-area air-fuel ratio sensor provided with a diffusion resistance layer, and is an example of the “first detection means” according to the present invention.
  • the air-fuel ratio sensor 221 outputs the output voltage value Vafin (that is, the “air-fuel ratio according to the present invention” corresponding to the input-side air-fuel ratio A / Fin that is the air-fuel ratio of the exhaust (that is, catalyst inflow gas) upstream of the three-way catalyst 220.
  • This is a sensor that outputs an example of “equivalent value”. That is, the air-fuel ratio sensor 221 employs a configuration in which the input-side air-fuel ratio A / Fin is indirectly detected by a voltage value having a unique relationship with the input-side air-fuel ratio A / Fin.
  • the output voltage value Vafin matches the reference output voltage value Vst when the input side air-fuel ratio A / Fin is the stoichiometric air-fuel ratio.
  • the output voltage value Vafin is lower than the reference output voltage value Vst when the input side air-fuel ratio A / Fin is on the air-fuel ratio rich side, and when the input-side air-fuel ratio A / Fin is on the air-fuel ratio lean side. It becomes higher than the reference output voltage value Vst. That is, the output voltage value Vafin continuously changes with respect to the change of the input side air-fuel ratio A / Fin.
  • the air-fuel ratio sensor 221 is electrically connected to the ECU 100, and the detected output voltage value Vafin is referred to by the ECU 100 at a constant or indefinite period.
  • an O 2 sensor 222 that can detect the downstream oxygen concentration Coxs that is the oxygen concentration of the catalyst exhaust gas that has passed through the three-way catalyst 220 is installed.
  • the O 2 sensor 222 is a known electromotive force type oxygen concentration sensor (that is, a concentration cell type oxygen concentration sensor using stabilized zirconia), and is an example of the “second detection means” according to the present invention.
  • the O 2 sensor 222 is a sensor that outputs an output voltage value Voxs (that is, an example of an “air-fuel ratio equivalent value” according to the present invention) corresponding to the downstream oxygen concentration Coxs. That is, the O 2 sensor 222 adopts a configuration in which the oxygen concentration is indirectly detected by a voltage value having a unique relationship with the oxygen concentration.
  • Voxs that is, an example of an “air-fuel ratio equivalent value” according to the present invention
  • the output voltage value Voxs of the O 2 sensor 222 is a reference when the air-fuel ratio of the catalyst exhaust gas is the stoichiometric air-fuel ratio (in other words, when the downstream oxygen concentration Coxs is the reference oxygen concentration Coxsb corresponding to the stoichiometric air-fuel ratio). It corresponds to the output voltage value Voxsb (for example, about 0.5V).
  • the output voltage value Voxs is higher than the reference output voltage value Voxsb when the air-fuel ratio of the catalyst exhaust gas is on the air-fuel ratio rich side with respect to the stoichiometric air-fuel ratio, and when the air-fuel ratio is also on the air-fuel ratio lean side. It becomes lower than the reference output voltage value Voxsb.
  • the output voltage value Voxs of the O 2 sensor 222 is a decrease in the air-fuel ratio (ie, oxygen concentration). With a decrease in Coxs), it increases relatively linearly and substantially linearly to a maximum output voltage value Voxsmax (for example, about 0.9 V) corresponding to the rich-side detection limit air-fuel ratio. In the air-fuel ratio region on the rich side with respect to the rich-side detection limit air-fuel ratio, the output voltage value Voxs is substantially constant at the maximum output voltage value Voxsmax.
  • the output voltage value Voxs of the O 2 sensor 222 increases the air-fuel ratio (that is, the oxygen concentration Coxs increases).
  • a minimum output voltage value Voxsmin for example, about 0.1 V
  • the output voltage value Voxs is substantially constant at the minimum output voltage value Voxsmin.
  • the O 2 sensor 222 is electrically connected to the ECU 100, and the detected output voltage value Voxs is referred to by the ECU 100 at a constant or indefinite period.
  • a water temperature sensor 223 capable of detecting a cooling water temperature Tw, which is a temperature of cooling water (LLC) circulated and supplied to cool the engine 200, is installed in a water jacket installed so as to surround the cylinder block CB. It is arranged.
  • the water temperature sensor 223 is electrically connected to the ECU 100, and the detected cooling water temperature Tw is referred to by the ECU 100 at a constant or indefinite period.
  • the intake pipe 206 is provided with an air flow meter 224 capable of detecting the intake air amount Ga.
  • the air flow meter 224 is electrically connected to the ECU 100, and the detected intake air amount Ga is referred to by the ECU 100 at a constant or indefinite period.
  • the engine 200 according to the present embodiment is a non-supercharged engine using gasoline as a fuel, but the configuration of the internal combustion engine according to the present invention is not limited to the engine 200 and may be various.
  • the internal combustion engine according to the present invention has the number of cylinders, cylinder arrangement, fuel type, fuel injection mode, intake / exhaust system configuration, valve operating system configuration, combustion system, presence / absence of supercharger, supercharging mode, etc.
  • the engine 200 may be different.
  • the engine system 10 may include a diesel engine that is a compression self-ignition internal combustion engine instead of the engine 200, or a direct injection capable of injecting fuel into the cylinder instead of or in addition to the intake port injector 212.
  • You may provide the direct-injection engine provided with the injection injector.
  • lean burn lean combustion
  • a supercharger may be installed in the intake system.
  • the compressor of the supercharger may be configured to be driven by an exhaust turbine, or may be configured to be mechanically driven by engine torque.
  • the construction mode of the catalyst system in the exhaust system may be different if the engine mode is different, the concept of sulfur poisoning recovery control described later can be applied to any configuration.
  • the air-fuel ratio F / B control includes a main F / B control and a sub F / B control.
  • the main F / B control is control of the fuel injection amount so that the input side air-fuel ratio A / Fin obtained based on the output voltage value Vafin of the air-fuel ratio sensor 221 converges to the input side target air-fuel ratio A / Fintg. is there.
  • the sub F / B control is a control for correcting the output voltage value Vafin of the air-fuel ratio sensor 221 or the input side target air-fuel ratio A / Fintg so that the output voltage value Voxs of the O 2 sensor 222 converges to the target output voltage value Voxstg. is there.
  • the target air-fuel ratio is an air-fuel ratio that optimizes the exhaust purification action of the three-way catalyst 220, and is, for example, a theoretical air-fuel ratio.
  • this target air-fuel ratio may be changed as appropriate according to the required performance of the engine 200, etc., as long as it is allowed in consideration of emissions and fuel consumption, and may be changed as appropriate.
  • the ECU 100 In executing the main F / B control and the sub F / B control, the ECU 100 functions as an example of the “air-fuel ratio control means” in the present invention.
  • Various feedback controls based on the values corresponding to the air / fuel ratio upstream and downstream of the catalyst have been proposed in the past, and further details are omitted here for the purpose of preventing complication of explanation.
  • FIG. 2 is a flowchart of the sulfur poisoning recovery control. Note that the sulfur poisoning recovery control is executed by the ECU 100 as a subroutine of the air-fuel ratio F / B control described above.
  • the ECU 100 acquires the sulfur accumulation amount Asf of the three-way catalyst 220 (step S101).
  • the sulfur accumulation amount Asf is the amount of sulfur accumulated in the three-way catalyst 220 during the period from the end of the previous sulfur poisoning recovery control to the present. Is an example.
  • the sulfur accumulation amount Asf is repeatedly calculated by the ECU 100 in a control routine different from the sulfur poisoning recovery control, and is stored in a rewritable memory such as a RAM with appropriate updating. That is, in the process of calculating the sulfur accumulation amount Dsf, the ECU 100 functions as an example of “accumulation amount estimation means” according to the present invention.
  • the ECU 100 estimates the sulfur accumulation amount Dsf from the accumulated fuel consumption amount ⁇ Qpfi that is a value obtained by accumulating the fuel injection amount Qpfi for each cycle of each cylinder. It is assumed that the sulfur content in the unit fuel is given as an initial value in advance.
  • the ECU 100 calculates the sulfur accumulation amount Dsf by multiplying the accumulated fuel consumption amount ⁇ Qpfi at that time by a predetermined accumulation rate ⁇ .
  • the accumulation rate ⁇ is a correction coefficient that represents the ratio of sulfur accumulated in the three-way catalyst 220 among the sulfur discharged to the exhaust pipe 219, and is experimentally, empirically, or theoretically preliminarily experimentally and empirically or theoretically.
  • the load factor KL (that is, the ratio of the fresh air amount taken into the cylinder 201 with respect to the physical maximum value) is stored in the control map as a parameter.
  • the ECU 100 acquires the in-catalyst hydrogen generation amount Ah2cat (step S102).
  • the in-catalyst hydrogen production amount Ah2cat is an integrated amount of hydrogen produced by the three-way catalyst 220 in the period from the end of the previous sulfur poisoning recovery control to the present, Is an example.
  • the in-catalyst hydrogen generation amount Ah2cat is repeatedly calculated by the ECU 100 in a control routine different from the sulfur poisoning recovery control, and stored in a rewritable memory such as a RAM with appropriate updating. That is, in the process of calculating the in-catalyst hydrogen generation amount Ah2cat, the ECU 100 functions as an example of the “in-catalyst generation amount estimation means” according to the present invention.
  • the ECU100 acquires in-catalyst hydrogen production amount Ah2cat based on catalyst bed temperature Tcat of the three-way catalyst 220. More specifically, the ROM of the ECU 100 stores a first hydrogen concentration map that defines the relationship between the catalyst bed temperature Tcat and the hydrogen concentration, and the ECU 100 reads the catalyst bed temperature Tcat from the first hydrogen concentration map. The hydrogen concentration corresponding to is estimated, and the in-catalyst hydrogen generation amount Ah2cat is calculated from the estimated hydrogen concentration.
  • the catalyst bed temperature Tcat is based on the accumulated fuel consumption (conceptually similar to the previous ⁇ Qpfi) after the latest IG ON timing in a control routine different from the sulfur poisoning recovery control. Presumed. Specifically, a control map representing the relationship between the accumulated fuel consumption and the catalyst bed temperature Tcat is stored in advance in the ROM, and the ECU 100 acquires a temperature value corresponding to the accumulated fuel consumption from the control map. As a result, the catalyst bed temperature Tcat is estimated. In addition, when a temperature sensor is arrange
  • FIG. 3 is a conceptual diagram of the first hydrogen concentration map.
  • the vertical axis and the horizontal axis represent the hydrogen concentration and the catalyst bed temperature Tcat in the three-way catalyst 220, respectively.
  • corresponding hydrogen is generated on both the low temperature side and the high temperature side, with a hydrogen deficient region (hatched region) located in the temperature region around 600 ° C. being the boundary.
  • hydrogen deficient region located in the temperature region around 600 ° C. being the boundary.
  • hydrogen is generated mainly by the water gas shift reaction
  • hydrogen is generated mainly by the steam reforming reaction.
  • the hydrogen concentration is because the hydrogen amount depends on the total amount of the catalyst inflow gas flowing into the three-way catalyst 220. That is, the ECU 100 estimates the amount of hydrogen generated in the three-way catalyst 220 per unit time based on the hydrogen concentration acquired from the first hydrogen concentration map, the engine speed NE, and the load factor KL. The estimated amount of hydrogen generated per unit time is accumulated as needed, and the accumulated value is temporarily stored in a storage means such as a RAM.
  • the in-catalyst hydrogen production amount Ah2cat is the stored integrated value.
  • the ECU 100 calculates the corrected accumulation amount Asfcor based on the sulfur accumulation amount Asf acquired in step S101 and the in-catalyst hydrogen generation amount Ah2cat acquired in step S102 (step S103).
  • the corrected accumulation amount Asfcor is an amount obtained by subtracting the reduction amount due to the reduction action of the hydrogen generated in the three-way catalyst 220 from the sulfur accumulated in the three-way catalyst 220. It is the amount of sulfur estimated to be accumulated in.
  • the ECU 100 determines whether or not the calculated corrected accumulation amount Asfcor is larger than the reference value Asfcorth (step S104).
  • the reference value Asfcorth is previously determined experimentally, empirically, or theoretically as a value that reduces the purification efficiency of the three-way catalyst 220 to a predetermined value or more.
  • step S104 the ECU 100 ends the sulfur poisoning recovery control. Since the sulfur poisoning recovery control is a subroutine of the air-fuel ratio F / B control as described above, it is executed again when the execution condition is satisfied in the air-fuel ratio F / B control.
  • step S104 determines that the three-way catalyst 220 needs to be recovered from sulfur poisoning, and performs the processing after step S105. Execute. That is, in this case, the ECU 100 functions as an example of the “determination unit” according to the present invention. Further, the process from step S105 to step S109 is an example of “sulfur poisoning recovery” according to the present invention.
  • step S105 the required H2 amount Nh2 is calculated.
  • the required H2 amount Nh2 is a required amount of hydrogen that needs to be generated in the cylinder 201, and is an example of the “required amount of hydrogen in the cylinder” according to the present invention.
  • the required H2 amount Nh2 is the amount of hydrogen necessary to reduce sulfur corresponding to the corrected accumulation amount Asfcor calculated in step S103, and its calculation algorithm is given experimentally, empirically or theoretically in advance. It has been.
  • the ECU 100 determines the air-fuel ratio imbalance degree IMB in each cylinder (step S106).
  • the air-fuel ratio imbalance degree IMB is an index value of variation in the air-fuel ratio between cylinders, and can be defined in various ways in practice.
  • the air-fuel ratio imbalance degree IMB in this embodiment is defined as a ratio of a deviation between the theoretical air-fuel ratio and the control air-fuel ratio of each cylinder with respect to the theoretical air-fuel ratio. That is, if the theoretical air-fuel ratio is X and the air-fuel ratio of a certain cylinder is Y, the degree of imbalance of the cylinder is (XY) / X ⁇ 100 (%).
  • the imbalance degree of the cylinder is about 32%.
  • the air-fuel ratio of a certain cylinder is 18, the imbalance degree of that cylinder is about ⁇ 23%.
  • the degree of variation in the air-fuel ratio of each cylinder is indirectly expressed through the theoretical air-fuel ratio.
  • the determination of the imbalance degree IMB is equivalent to determining the target value of the air-fuel ratio of each cylinder in the sulfur poisoning recovery control according to the definition.
  • the ECU 100 refers to the second hydrogen concentration map stored in the ROM when determining the imbalance degree IMB of each cylinder.
  • the second hydrogen concentration map will be described with reference to FIG.
  • FIG. 4 is a conceptual diagram of the second hydrogen concentration map.
  • the vertical axis and the horizontal axis represent the hydrogen concentration and the imbalance degree IMB (%), respectively.
  • the degree of imbalance IMB 0 means the stoichiometric air-fuel ratio according to the above-described definition.
  • the concentration of generated hydrogen increases inside the cylinder.
  • the lean misfire limit on the lean side has a smaller margin for the stoichiometric air-fuel ratio than the rich misfire limit on the rich side. Therefore, the range that can be taken as the imbalance degree IMB is wider on the rich side (positive value), and the hydrogen generation by rich combustion has higher controllability.
  • the hydrogen concentration with respect to the imbalance degree IMB also changes with respect to the engine speed NE and the load factor KL.
  • the hydrogen concentration decreases when the engine speed NE is low or the load factor KL is small (see the chain line in the figure).
  • the hydrogen concentration increases (see the broken line in the drawing).
  • the relationship shown in the figure is stored in a numerical state in advance, and the ECU 100 determines the hydrogen concentration with respect to the imbalance degree IMB based on the engine speed NE and the load factor KL at that time. Can be estimated. Further, the total amount of gas discharged from the cylinder per unit time can be estimated based on the engine speed NE and the load factor KL. Therefore, the ECU 100 can calculate the hydrogen generation amount Gh2 in the cylinder 201 in which a certain imbalance degree IMB is selected.
  • the imbalance degree IMB of each cylinder is determined so that the air-fuel ratio of the entire cylinder of the engine 200 matches the input target air-fuel ratio AFintg or the theoretical air-fuel ratio as much as possible. Therefore, when one cylinder 201 is controlled to the air-fuel ratio rich side (or lean side) when imbalance is generated between the cylinders, at least a part of the other cylinders is controlled to the lean side (or rich side). Is done. At this time, the cylinder controlled to the rich side and the cylinder controlled to the lean side alternately reach the combustion stroke in time series so that the fluctuation of the engine torque of the engine 200 is minimized. Thus, the air-fuel ratio of each cylinder may be determined.
  • the combination of the imbalance degree IMB of each cylinder that can maintain the air-fuel ratio at the input side target air-fuel ratio A / Fintg or the stoichiometric air-fuel ratio in the plurality of cylinders as a whole is not unique.
  • the imbalance degree IMB of the remaining cylinders other than the rich cylinder may be determined, or more simply, the average air-fuel ratio of all the cylinders may be determined.
  • the provisional air-fuel ratio of the remaining cylinders may be determined so that the theoretical air-fuel ratio or the input-side target air-fuel ratio A / Fintg is obtained.
  • the latter technique refers to the following, for example.
  • the amount of fuel required to make the average air-fuel ratio of the entire cylinder the stoichiometric air-fuel ratio or the input-side target air-fuel ratio A / Fintg is “10” (that is, one cylinder
  • the fuel amount required for the cycle is “2, 5”).
  • the fuel injection amount of the rich cylinder controlled to the rich side is “4”
  • the fuel amount to be injected in the remaining three cylinders is “6”.
  • the fuel injection amount of each remaining cylinder is set to “2”, or the fuel injection amount is maintained at “2.5” for two of the remaining three cylinders, and the remaining one cylinder Only the fuel injection amount is set to “1”. Even in this case, the fuel injection amount of the entire cylinder is maintained at the target value, and the average air-fuel ratio of the catalyst inflow gas flowing into the three-way catalyst 220 is maintained at the theoretical air-fuel ratio or the input-side target air-fuel ratio A / Fintg. I can do it.
  • the imbalance degree IMB of at least one cylinder 201 is equal to the previously calculated H2 required amount Nh2.
  • H2 required amount Nh2 the previously calculated H2 required amount
  • the air-fuel ratio of as many cylinders as possible is controlled to the rich side or the lean side, and the combustion stroke is rich cylinder ⁇ lean cylinder ⁇ rich cylinder as described above.
  • the imbalance degree IMB of each cylinder is determined so as to maximize the amount of hydrogen generated per unit time. .
  • the ECU 100 switches the target air-fuel ratio of each cylinder according to the determined imbalance degree IMB. (Step S107).
  • the port injector 212 is driven and controlled in accordance with a normal fuel injection control routine, and fuel injection for causing imbalance between cylinders is realized.
  • the ECU 100 counts the hydrogen generation amount ⁇ Gh2 in the entire cylinder after the start of the imbalance control as an integrated value of the hydrogen generation amount Gh2 of each cylinder (step S108). Subsequently, it is determined whether or not the counted hydrogen generation amount ⁇ Gh2 has exceeded the previously calculated H2 required amount Nh2 (step S109). (S109: NO), the process is returned to step S108, and the imbalance control is continued.
  • step S109 When the hydrogen generation amount ⁇ Gh2 becomes larger than the H2 required amount Nh2 (step S109: YES), the ECU 100 controls the sulfur accumulation amount estimation subroutine so that the sulfur accumulation amount Asf is cleared (step S110). End poisoning recovery control.
  • the hydrogen generation amount ⁇ Gh2 and the H2 required amount Nh2 are compared, but hydrogen generation in the three-way catalyst 220 is separately performed even during a period in which hydrogen is generated in the cylinder due to the air-fuel ratio imbalance. proceed. Therefore, the ECU 100 may execute step S109 by adding the in-catalyst hydrogen generation amount Ah2cat to the hydrogen generation amount ⁇ Gh2 during the period of recovery from sulfur poisoning due to the air-fuel ratio imbalance.
  • the H2 required amount Nh2 may be corrected to the decreasing side in consideration of the in-catalyst hydrogen generation amount Ah2cat in calculating the H2 required amount Nh2.
  • the sulfur poisoning of the three-way catalyst 220 is reduced without causing an increase in cost by causing an air-fuel ratio imbalance between the cylinders. It is possible to recover. Further, since the degree of imbalance IMB of each cylinder is determined so that the air-fuel ratio of the entire cylinder becomes the stoichiometric air-fuel ratio or the input-side target air-fuel ratio A / Fintg, the air-fuel ratio of the catalyst inflow gas flowing into the three-way catalyst 220 Is substantially maintained at the theoretical air fuel ratio or the input side target air fuel ratio A / Fintg. Therefore, sulfur poisoning of the three-way catalyst 220 can be efficiently and effectively recovered while suppressing deterioration of exhaust emission and fuel consumption.
  • the intake port injector 212 is used as a device for generating an air-fuel ratio imbalance.
  • the fuel injection device is reasonable and appropriate as this type of device.
  • control amounts include the opening / closing timing of the intake valve and the EGR rate of the EGR device.
  • the intake air amount decreases due to the return of intake air in the vicinity of the valve closing timing IVC. Therefore, if the fuel injection amount is constant, the air-fuel ratio shifts relatively to the rich side.
  • the opening / closing timing of the intake valve 209 can be controlled independently for each cylinder, the air-fuel ratio imbalance can be generated by controlling the opening / closing timing.
  • the engine 200 may more preferably include a mechanism capable of independently controlling the operating angle or valve lift amount of the intake valve 209 or the exhaust valve 215 of each cylinder. If the operating angle or valve lift amount can be controlled independently for each cylinder, a relatively large control range can be obtained for the intake air amount for each cylinder. Therefore, the control range of the air-fuel ratio imbalance can be made relatively large.
  • a mechanism may include, for example, an electromagnetic drive device that opens and closes an intake valve or an exhaust valve for each cylinder.
  • each cylinder may have an intake throttle valve independently. In this case, even if the opening / closing characteristics of the valve are uniform for each cylinder, the intake air amount can be changed for each cylinder. That is, an air-fuel ratio imbalance can be generated.
  • the EGR device can also be used as a device that causes an air-fuel ratio imbalance.
  • the EGR rate can be independently controlled for each cylinder by controlling the open / close state of the EGR valve provided in each EGR pipe. .
  • the ratio of fresh air to in-cylinder intake gas can be changed, and an air-fuel ratio imbalance can be generated.
  • the determination regarding whether or not to perform sulfur poisoning recovery is performed based on the sulfur accumulation amount Asf and the in-catalyst hydrogen generation amount Ah2cat, but this is an example. Yes, the ECU 100 may perform the determination based only on the sulfur accumulation amount Asf. For example, when the sulfur accumulation amount Asf is greater than or equal to a predetermined value, the processing after step S105 may be executed.
  • the ECU 100 may make the determination based only on the in-catalyst hydrogen generation amount Ah2cat. For example, when the amount of hydrogen generated in the catalyst Ah2cat in a predetermined period is equal to or less than a reference value, it is determined that the processing for sulfur poisoning recovery should be performed because the necessity for sulfur poisoning recovery is large. Also good.
  • FIG. 5 is a flowchart of the sulfur poisoning recovery control.
  • the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof will be omitted as appropriate.
  • the ECU 100 calculates the retard amount of the ignition timing by the ignition device 213 (step S201). ).
  • the catalyst bed temperature Tcat affects the amount of hydrogen generated in the three-way catalyst 220 (in-catalyst hydrogen generation amount Ah2cat) as described above.
  • the catalyst bed temperature Tcat also increases in the air-fuel ratio imbalance control accompanied by the enrichment of the air-fuel ratio.
  • the air-fuel ratio imbalance degree IMB as one control element has two hydrogen generation amounts Gh2 and catalyst bed temperature Tcat. The state quantity cannot be controlled independently. Therefore, the retard amount of the ignition timing is used as a control element for controlling the catalyst bed temperature Tcat.
  • the retard amount of the ignition timing is executed, for example, when the execution period of the sulfur poisoning recovery control can be shortened by the retard of the ignition timing.
  • the effect is executed so that the influence can be mitigated by increasing the catalyst bed temperature Tcat.
  • ignition timing retardation control is executed following the target air-fuel ratio switching control (imbalance control) (step S202).
  • the hydrogen generation amount Gh2 in the cylinder and the catalyst bed temperature Tcat can be independently controlled by retarding the ignition timing, the sulfur poisoning of the three-way catalyst 220 is prevented. In the recovery, the combustion state in the cylinder can be made more desirable.
  • the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the control of the internal combustion engine accompanying such a change.
  • the apparatus is also included in the technical scope of the present invention.
  • the present invention can be applied to sulfur poisoning recovery control of a catalyst in an internal combustion engine.
  • 10 engine system, 100 ... ECU, 200 ... engine, CB ... Cylinder block, 201 ... cylinder, 212 ... intake port injector, 219 ... exhaust pipe, 220 ... three-way catalyst, 221 ... air-fuel ratio sensor, 222 ... O 2 sensor .

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

La présente invention porte sur la régénération d'un catalyseur, qui est dans un état d'empoisonnement par le soufre, tout en réduisant à un minimum les accroissements des coûts, les accroissements des émissions d'échappement et les réductions du rendement en carburant. Ce dispositif de commande (100), qui commande un moteur à combustion interne (200) comportant une pluralité de cylindres (201) et un catalyseur d'épuration d'échappement (220) monté dans un passage d'échappement relié à la pluralité de cylindres, comprend les éléments suivants : un moyen de détermination qui détermine si une régénération après empoisonnement du catalyseur par le soufre doit ou ne doit pas exécutée ; et un moyen de commande de régénération après empoisonnement qui, s'il a été déterminé que ladite régénération après empoisonnement par le soufre doit être exécutée, règle le rapport air-carburant du gaz d'échappement arrivant au catalyseur. Le dispositif de commande de régénération après empoisonnement règle le degré de déséquilibre du rapport air-carburant parmi la pluralité de cylindres.
PCT/JP2012/059724 2012-04-09 2012-04-09 Dispositif de commande pour moteur à combustion interne WO2013153610A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005207404A (ja) * 2003-12-26 2005-08-04 Denso Corp 内燃機関の空燃比制御装置
JP2006242124A (ja) * 2005-03-04 2006-09-14 Toyota Motor Corp 内燃機関の排気浄化装置
JP2007154840A (ja) * 2005-12-08 2007-06-21 Toyota Motor Corp 内燃機関の空燃比制御装置
JP2009022821A (ja) * 2007-07-17 2009-02-05 Honda Motor Co Ltd ＮＯｘ浄化触媒
JP2010174739A (ja) * 2009-01-29 2010-08-12 Toyota Motor Corp 内燃機関の排気浄化装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005207404A (ja) * 2003-12-26 2005-08-04 Denso Corp 内燃機関の空燃比制御装置
JP2006242124A (ja) * 2005-03-04 2006-09-14 Toyota Motor Corp 内燃機関の排気浄化装置
JP2007154840A (ja) * 2005-12-08 2007-06-21 Toyota Motor Corp 内燃機関の空燃比制御装置
JP2009022821A (ja) * 2007-07-17 2009-02-05 Honda Motor Co Ltd ＮＯｘ浄化触媒
JP2010174739A (ja) * 2009-01-29 2010-08-12 Toyota Motor Corp 内燃機関の排気浄化装置

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