EP1515029A2 - Système de purification des gaz d'échappement pour un moteur à combustion interne - Google Patents

Système de purification des gaz d'échappement pour un moteur à combustion interne Download PDF

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Publication number
EP1515029A2
EP1515029A2 EP04021239A EP04021239A EP1515029A2 EP 1515029 A2 EP1515029 A2 EP 1515029A2 EP 04021239 A EP04021239 A EP 04021239A EP 04021239 A EP04021239 A EP 04021239A EP 1515029 A2 EP1515029 A2 EP 1515029A2
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EP
European Patent Office
Prior art keywords
sox
exhaust
nox catalyst
fuel
air
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
EP04021239A
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German (de)
English (en)
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EP1515029A3 (fr
EP1515029B1 (fr
Inventor
Nobuki Kobayashi
Tatsumasa Sugiyama
Jun Tahara
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Toyota Motor Corp
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Toyota Motor Corp
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Publication of EP1515029A3 publication Critical patent/EP1515029A3/fr
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—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
    • F02D41/0275—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 the exhaust gas treating apparatus being a NOx trap or adsorbent
    • F02D41/028—Desulfurisation of NOx traps or adsorbent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0611—Fuel type, fuel composition or fuel quality
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/08—Exhaust gas treatment apparatus parameters
    • F02D2200/0818—SOx storage amount, e.g. for SOx trap or NOx trap

Definitions

  • the invention relates to an exhaust purification system of an internal combustion engine.
  • NOx catalyst An occlusion and reduction type NOx catalyst (hereinafter simply referred to as NOx catalyst) has been developed in order to purify nitrogen oxides (NOx) in exhaust that is discharged from an internal combustion engine, more particularly, a lean-burn internal combustion engine.
  • NOx catalyst occludes NOx in exhaust into the catalyst when the atmosphere within range of the catalyst is in a high oxygen concentration state.
  • HC unburned fuel constituents
  • the occlusion and reduction type NOx catalyst occludes and deposits sulfur oxides (SOx) in exhaust as well as NOx.
  • SOx sulfur oxides
  • a problem occurs in accordance with an increase in the SOx deposit amount in the NOx catalyst, whereby an exhaust purification function of the NOx catalyst deteriorates, and sufficient NOx purification is not performed.
  • a deterioration in an oxidation function of the NOx catalyst is another problem.
  • an art disclosed in Japanese Patent Laid-Open Publication No. 07-217474 raises a temperature of a NOx catalyst in which a deposit amount of SOx is increased, and exposes the NOx catalyst to an atmosphere where HC exists with a constant air-fuel ratio, thereby removing SOx deposited in the NOx catalyst from the catalyst.
  • control for recovering the exhaust purification function of the NOx catalyst (hereinafter referred to as SOx poisoning recovery control) is executed.
  • SOx poisoning recovery control in order to expose the NOx catalyst to an atmosphere where HC exists with a constant air-fuel ratio, for example, a method, is used in which an air-fuel ratio of exhaust is changed to a rich side by feeding additional fuel into an exhaust passage.
  • Japanese Patent Laid-Open Publication No. 2000-161107 discloses art that controls an operation of an internal combustion engine so as to suppress the degree of discharge of SOx based on a SOx amount deposited in the NOx catalyst, so as not to generate a large amount of SOx in a short time in the process of SOx removal.
  • an object of the present invention to provide an exhaust purification system of an internal combustion engine that inhibits a large amount of HC from being discharged to the atmosphere, in addition to inhibiting the generation of white smoke, when SOx deposited in a NOx catalyst is removed by SOx poisoning recovery control.
  • an exhaust purification system of an internal combustion engine includes a NOx catalyst for occluding and reducing NOx in exhaust, and performs SOx poisoning recovery control for removing SOx deposited in the NOx catalyst by adjusting an air-fuel ratio of exhaust flowing into the NOx catalyst to a predetermined air-fuel ratio.
  • the exhaust purifying system of an internal combustion engine further includes SOx deposit amount estimating means for estimating a SOx deposit amount of the NOx catalyst, detecting means for detecting a concentration of sulfur in a fuel used for the internal combustion engine, and air-fuel ratio control means for changing an air-fuel ratio of exhaust when performing the SOx poisoning recovery control to a richer side air-fuel ratio depending on a decrease in the estimated SOx deposit amount.
  • the NOx catalyst occludes NOx in exhaust into the catalyst in an atmosphere with a high oxygen concentration.
  • the NOx catalyst purifies exhaust by reducing NOx occluded in the catalyst in an atmosphere with a low oxygen concentration and where unburned constituents of a fuel that are reducing constituents exist.
  • SOx in exhaust is also occluded and deposited in the NOx catalyst, and with an increase in the SOx deposit amount, an exhaust purification function and an oxidation function of the NOx catalyst deteriorate.
  • the exhaust purification function and the oxidation function of the NOx catalyst are designed to be recovered by the SOx poisoning recovery control.
  • an air-fuel ratio of exhaust flowing into the NOx catalyst is adjusted to the predetermined air-fuel ratio by adding fuel into exhaust or by adjusting an injection amount or injection timing of the fuel in a combustion chamber, or the like, whereby HC as a reducing agent is supplied to the NOx catalyst.
  • HC as a reducing agent
  • SOx deposited in the NOx catalyst is removed.
  • the aforementioned predetermined air-fuel ratio is an air-fuel ratio of exhaust when HC required for removing SOx deposited in the NOx catalyst is supplied to the NOx catalyst.
  • the oxidation function of the NOx catalyst varies depending on the SOx deposit amount. Accordingly, assuring that an air-fuel ratio of exhaust flowing into the NOx catalyst is a constant air-fuel ratio, since the oxidation function of the NOx catalyst deteriorates when the SOx deposit amount in the NOx catalyst is large, there is a possibility that HC in the exhaust subject to the SOx poisoning recovery control will not be oxidized by the NOx catalyst and discharged to the atmosphere.
  • the air-fuel ratio of the exhaust flowing into the NOx catalyst is controlled to a richer side depending on a decrease in the SOx deposit amount estimated by the SOx deposit amount estimating means so that a large amount of HC is not included in exhaust flowing out from the NOx catalyst.
  • the SOx deposit amount of the NOx catalyst gradually decreases and the oxidation function of the NOx catalyst is also gradually recovered. Consequently, depending on a degree of the recovery, an air-fuel ratio of exhaust is changed to the rich side.
  • the SOx deposit amount is large and the oxidation function of the NOx catalyst is still low, that is, immediately after the SOx poisoning control is started or the like, the air-fuel ratio of exhaust flowing into the NOx catalyst is changed to a lean side air-fuel ratio.
  • the air-fuel ratio of exhaust flowing into the NOx catalyst is changed to a richer side air-fuel ratio. Accordingly, it is possible to supply the NOx catalyst with HC corresponding to the oxidation function of the NOx catalyst that is determined by the SOx deposit amount. As a result, it is possible to suppress a concentration of HC in exhaust flowing out from the NOx catalyst to a level that is equal to or less than a permissible HC concentration. Accordingly, it is possible to inhibit a large amount of HC from being discharged to the atmosphere, thereby inhibiting the generation of white smoke.
  • the above SOx deposit amount estimating means is also suitable for application to estimation of the SOx deposit amount of the NOx catalyst, taking into consideration the concentration of sulfur in the fuel detected by the detecting means.
  • the concentration of sulfur in the fuel used for the internal combustion engine is detected by the detecting means, and when estimating the SOx deposit amount using the SOx deposit amount estimating means, the detected concentration of sulfur in the fuel is taken into consideration.
  • an increase trend of the SOx deposit amount accompanied by the fuel consumption in the internal combustion engine becomes more distinct as the concentration of the sulfur in the fuel becomes higher.
  • the SOx deposit amount is estimated assuming that the amount of sulfur in the fuel is less than a predetermined rated value, in the case of feeding a fuel with a high sulfur concentration or the like, an estimated SOx deposit amount becomes less than an actual SOx deposit amount.
  • the air-fuel ratio of exhaust when an air-fuel ratio of exhaust is controlled depending on the estimated SOx deposit amount during the SOx poisoning recovery control, the air-fuel ratio becomes richer than an optimal value that corresponds to the actual SOx deposit amount.
  • the concentration of HC in exhaust becomes high, and there is a possibility that white smoke will be generated.
  • the concentration of sulfur in the fuel detected by the detecting means is taken into consideration. Accordingly, for example, in the case where fuel with a sulfur concentration higher than normal is fed, the SOx deposit amount is estimated taking into consideration the concentration of sulfur in the fuel. Thus, the estimated SOx deposit amount is controlled so as not to deviate from the actual SOx deposit amount. Therefore, the air-fuel ratio during the SOx poisoning recovery control can be prevented from becoming richer than the optimal value due to this deviation, which increases the concentration of HC in exhaust, leading to the generation of white smoke.
  • the air-fuel ratio control means is also suitable for correcting the air-fuel ratio based on the concentration of sulfur in the fuel detected by the detecting means.
  • the detecting means may detect the concentration of sulfur in the fuel used for the internal combustion engine, and in the case where the concentration is high, the air-fuel ratio of the exhaust may be corrected to the lean side with respect to the case where the concentration is low.
  • the air-fuel ratio of exhaust during the SOx poisoning recovery control is corrected depending on the concentration of sulfur in the fuel. More specifically, the detecting means detects the concentration of sulfur in the fuel used for the internal combustion engine. In the case where the concentration is high, the air-fuel ratio of the exhaust is corrected to the lean side with respect to the case where the concentration is low.
  • FIG. 1 is a schematic block diagram showing an exhaust purification system to which the invention is applied, and an internal combustion engine 1 and a control system thereof that include the exhaust purification system.
  • the internal combustion engine 1 is an internal combustion engine having four cylinders 2. Further, the internal combustion engine 1 is provided with fuel injection valves 3 that directly inject fuel into combustion chambers of cylinders 2. The fuel injection valves 3 are connected to an accumulator 4 that accumulates and pressurizes fuel to a predetermined pressure. The accumulator 4 communicates with a fuel pump 6 through a fuel supply pipe 5.
  • an intake branch pipe 7 is connected to the internal combustion engine 1, and each of sub-branch pipes of the intake branch pipe 7 communicates with the combustion chamber of each of the cylinders 2 through an intake port.
  • communication between the combustion chambers of the cylinders 2 and the intake ports is performed by opening and closing of intake valves (not shown).
  • the intake branch pipe 7 is connected to an intake pipe 8.
  • the intake pipe 8 is mounted with an air flow meter 9 that outputs an electric signal corresponding to the mass of intake air flowing through the intake pipe 8.
  • an inlet throttle valve 10 is provided that adjusts a flow amount of the intake air flowing through the intake pipe 8.
  • the inlet throttle valve 10 is provided with an actuator 11 for throttling intake air, which is structured with a step motor and the like, and actuates opening and closing of the inlet throttle valve 10.
  • a compressor housing 17a of a centrifugal supercharger (turbocharger) 17 that operates using exhaust energy as a power source.
  • an intercooler 18 for cooling intake air compressed in the compressor housing 17a that has reached a high temperature.
  • an exhaust branch pipe 12 is connected to the internal combustion engine 1, and each of sub-branch pipes of the exhaust branch pipe 12 communicates with the combustion chamber of each of the cylinders 2 through an exhaust port.
  • communication between the combustion chambers of the cylinders 2 and exhaust ports are performed by opening and closing of exhaust valves (not shown).
  • the exhaust branch pipe 12 is provided with a fuel addition valve 30 that adds fuel into exhaust flowing through the exhaust branch pipe 12.
  • the exhaust branch pipe 12 is connected to a turbine housing 17b of the centrifugal supercharger 17.
  • the turbine housing 17b is connected to an exhaust pipe 13, and the exhaust pipe 13 is connected to a muffler (not shown) at a downstream portion thereof.
  • a NOx catalyst 16 that purifies exhaust by occluding and reducing NOx in exhaust discharged from the internal combustion engine.
  • an exhaust purification device that is a filter by which a NOx catalyst is supported, and which has a function for trapping particulate matter in exhaust may be used.
  • the exhaust pipe 13 located downstream of the NOx catalyst 16 is provided with an exhaust throttle valve 14 that adjusts a flow amount of exhaust flowing through the exhaust pipe 13.
  • the exhaust throttle valve 14 is mounted with an actuator 15 for throttling exhaust which is structured with the step motor and the like, and actuates opening and closing of the exhaust throttle valve 14.
  • the fuel injection valve 3 and the fuel addition valve 30 open and close based on control signals from an electronic control unit (hereinafter referred to as ECU) 20.
  • ECU electronice control unit
  • injection timing and an injection amount of fuel at the fuel injection valve 3 and the fuel addition valve 30 are controlled by the valves, respectively.
  • the ECU 20 is electrically connected to an accelerator opening degree sensor 19, a crank position sensor 33, and a high-sulfur-concentration fuel use switch 34.
  • the accelerator opening degree sensor 19 outputs a signal to the ECU 20 that corresponds to an accelerator opening degree
  • the crank position sensor 33 outputs a signal to the ECU 20 that corresponds to a turning angle of an output shaft of the internal combustion engine 1.
  • the ECU 20 receives the signal corresponding to the accelerator opening degree from the accelerator opening degree sensor 19, and based thereon, the ECU 20 calculates an engine output and the like required for the internal combustion engine 1. Further, the ECU 20 receives the signal corresponding to the turning angle of the output shaft of the internal combustion engine 1 from the crank position sensor 33, and calculates an engine rotational speed of the internal combustion engine 1, cycle condition in the cylinders 2 and the like.
  • the high-sulfur-concentration fuel use switch 34 is operated by a vehicle driver during fueling in accordance with the type of fuel used for the internal combustion engine 1.
  • a fuel with a sulfur concentration less than the predetermined rated value is commonly used.
  • the high-sulfur-concentration fuel use switch 34 is turned on by the driver.
  • the high-sulfur-concentration fuel use switch 34 is turned off by the driver.
  • the ECU 20 receives a signal from the high-sulfur-concentration fuel switch 34, and based thereon, the ECU 20 detects the sulfur concentration of the fuel used for the internal combustion engine 1.
  • the ECU 20 is electrically connected to an exhaust air-fuel ratio sensor 32, which is provided in a portion downstream of the NOx catalyst 16 and detects an air-fuel ratio of exhaust flowing out from the catalyst 16.
  • the exhaust air-fuel ratio sensor 32 transmits to the ECU 20 a voltage that corresponds to a concentration of oxygen in the exhaust, whereby the air-fuel ratio of the exhaust is detected.
  • the exhaust purification system structured with this sensor, the NOx catalyst 16 and the like, purifies exhaust discharged from the internal combustion engine 1.
  • SOx poisoning recovery control for removing the SOx deposited in the NOx catalyst is performed by the ECU 20.
  • the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is adjusted to a predetermined air-fuel ratio, whereby a floor temperature of the NOx catalyst 16 is adjusted to a suitable temperature, and HC as a reducing agent is supplied to the NOx catalyst 16.
  • the ECU 20 issues an injection command to the fuel addition valve 30, and based thereon, fuel is added into exhaust by the fuel addition valve 30, whereby the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is adjusted.
  • a part of the fuel added into the exhaust by the fuel addition valve 30 iSOxidized by an oxidation function of the NOx catalyst 16, whereby the floor temperature of the NOx catalyst 16 is increased. Further, the remaining fuel is supplied to the NOx catalyst 16, whereby a reducing agent required for the SOx poisoning recovery control is supplied.
  • Control for the air-fuel ratio of exhaust is performed such that the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is first estimated based on the air-fuel ratio detected by the exhaust air-fuel ratio sensor 32, and then, an amount of fuel added by the fuel addition valve 30 is controlled so that the estimated air-fuel ratio becomes the predetermined air-fuel ratio of exhaust.
  • a relationship between the air-fuel ratio of the exhaust in the NOx catalyst 16 and the air-fuel ratio detected by the exhaust air-fuel ratio sensor 32 may be obtained in advance by an experiment or the like, and stored in a ROM of the ECU 20 as a map.
  • the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is adjusted to the predetermined air-fuel ratio as described above.
  • the SOx amount deposited in the NOx catalyst 16 increases, the oxidation function of the NOx catalyst 16 deteriorates. Therefore, when the SOx amount deposited in the NOx catalyst 16 is large, for example, immediately after the SOx poisoning recovery control is started, if the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is an excessively rich side air-fuel ratio, an amount of HC that should be oxidized in the NOx catalyst 16 under normal conditions is not oxidized and passes through the NOx catalyst 16. Thus, a large amount of HC is discharged to the atmosphere, which may generate white smoke.
  • FIG. 2 is a flow chart showing the control for inhibiting the generation of white smoke during the SOx poisoning recovery control in the NOx catalyst 16. Note that the control is performed by the ECU 20 along with the SOx poisoning recovery control.
  • the amount of SOx deposited in the NOx catalyst 16 is estimated. More specifically, the amount of SOx deposited in the NOx catalyst 16 is estimated based on a fuel consumption amount in the internal combustion engine 1 consumed after completion of the last SOx poisoning recovery control, a driving distance of a vehicle equipped with the internal combustion engine 1 relevant to the fuel consumption amount, the sulfur concentration of the fuel for the internal combustion engine 1, or the like.
  • the processing at S100 is completed, the procedure proceeds to S101.
  • the SOx deposit amount in the NOx catalyst 16 estimated at S100 is larger than a predetermined deposit amount.
  • the predetermined deposit amount is a threshold value for determining that the deposited SOx should be removed, because the SOx amount deposited in the NOx catalyst 16 is large and an exhaust purification function of the NOx catalyst 16 has deteriorated. Therefore, if it is determined at S101 that the SOx deposit amount in the NOx catalyst 16 is larger than the predetermined deposit amount, processing from S103 onward is executed so as to remove the deposited SOx. On the other hand, if it is determined at S101 that the SOx deposit amount in the NOx catalyst 16 is equal to or less than the predetermined deposit amount, the processing at S100 is executed again.
  • the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is calculated such that the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is suitable for removing SOx deposited in the NOx catalyst 16, and an HC concentration in exhaust passing through the NOx catalyst 16 does not exceed a predetermined HC concentration. More specifically, considering the deterioration in the oxidation function of the NOx catalyst 16 in accordance with the increase in the SOx deposit amount of the NOx catalyst 16, when the SOx deposit amount of the NOx catalyst 16 is large, the air-fuel ratio is changed to a lean side air-fuel ratio.
  • the air-fuel ratio is calculated so as to become a rich side air-fuel ratio.
  • the relationship between the SOx deposit amount and the air-fuel ratio of the exhaust flowing into the NOx catalyst 16 is obtained in advance by an experiment or the like, and stored in the ROM of the ECU 20.
  • the predetermined HC concentration referred to here is a threshold value of the HC concentration at which it is determined that white smoke is generated in the exhaust discharged to the atmosphere.
  • the fuel addition valve 30 adds fuel to exhaust discharged from the internal combustion engine 1, whereby the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is controlled. More specifically, an amount of fuel added by the fuel addition valve 30 is controlled based on a value detected by the exhaust air-fuel ratio sensor 32 or the like, so that the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is adjusted to the air-fuel ratio of exhaust calculated at S103.
  • the processing at S104 is completed, the procedure proceeds to S105.
  • an amount of SOx deposited in the NOx catalyst 16 is estimated. This is the SOx deposit amount for which an amount of SOx removed from the NOx catalyst 16 by the fuel addition at S104 is taken into consideration. Accordingly, from now on, for control based on the SOx deposit amount of the NOx catalyst 16, such as the air-fuel ratio control of exhaust, the SOx deposit amount of the NOx catalyst 16 estimated at S105 is utilized. When the processing at S105 is completed, the procedure proceeds to S106.
  • the permissible deposit amount is a threshold value for determining that the exhaust purification function of the NOx catalyst 16 has been recovered based on the fact that the SOx amount deposited in the NOx catalyst 16 has decreased. Accordingly, when it is determined at S106 that the SOx amount deposited in the NOx catalyst 16 is equal to or less than the permissible deposit amount, it is determined that the deposited SOx of the NOx catalyst 16 has been removed, thus completing the control.
  • the air-fuel ratio of exhaust flowing into the NOx catalyst 16 is changed from a lean side air-fuel ratio to a rich side air-fuel ratio based on the decrease in the SOx deposit amount of the NOx catalyst 16. Therefore, it is possible to supress the concentration of HC in exhaust discharged to the atmosphere after passing through the NOx catalyst 16 to a level that is equal to or less than the predetermined concentration. Accordingly a large amount of HC is inhibited from being discharged to the atmosphere, and it is possible to inhibit the generation of white smoke.
  • an actual SOx deposit amount of the NOx catalyst 16 is affected by the sulfur concentration of the fuel used for the internal combustion engine 1. As the sulfur concentration becomes higher, an increase trend of the SOx deposit amount becomes more distinct. Note that as fuel used for the internal combustion engine 1, a fuel with a sulfur concentration less than the predetermined rated value is commonly used. Accordingly, in the processing at S100 and S105 in the flow chart of the SOx poisoning recovery control shown in FIG. 2, the SOx deposit amount can be estimated, assuming that the sulfur concentration of the fuel is less than the predetermined rated value. In the SOx poisoning recovery control, the air-fuel ratio of exhaust is controlled to an optimal value corresponding to the estimated SOx deposit amount. Note that the optimal value for the air-fuel ratio of exhaust during the SOx poisoning recovery control is changed to the rich side as the SOx deposit amount decreases, as shown in FIG. 3.
  • an air-fuel ratio B1 of exhaust suitable for the SOx deposit amount A1 is calculated in the SOx poisoning recovery control.
  • An amount of fuel added by the fuel addition valve 30 is then controlled so as to obtain the air-fuel ratio B1.
  • the value of the actual SOx deposit amount becomes A2, which is larger than A1, if the SOx deposit amount is estimated as described above. This is because the actual SOx deposit amount is increased by an amount corresponding to the use of a fuel with a sulfur concentration higher than the rated value, while the estimated SOx deposit amount A1 is estimated assuming that the sulfur concentration of the fuel is less than the rated value.
  • a value B2 is the air-fuel ratio of fuel suitable for performing the SOx poisoning recovery control, which corresponds to the actual SOx deposit amount A2.
  • the air-fuel ratio of exhaust is controlled to the value B1 that corresponds to the estimated SOx deposit amount A1. Accordingly, the air-fuel ratio of exhaust (here, B1) becomes richer than the optimal value (B2) that corresponds to the actual SOx deposit amount, and consequently the concentration of HC in exhaust becomes high, possibly leading to the generation of white smoke.
  • a SOx deposit amount estimating routine as shown in FIG. 4 is executed as processing for estimating the SOx deposit amount at S100 and S105 in the flow chart of FIG. 2.
  • the SOx deposit amount estimating routine is executed through the ECU 20 every time the procedure proceeds to the aforementioned S100 and S105.
  • a fuel has a sulfur concentration higher than the rated value. Such a determination is made based on a signal from the high-sulfur-concentration fuel use switch 34 operated by the vehicle driver. In this case, when a fuel with a sulfur concentration higher than the rated value is fed, the high-sulfur-concentration fuel use switch 34 is turned on by the driver. Thus, it is determined that the sulfur concentration of the fuel is high based on the signal from the switch 34 in response to the turning-on operation. In other words, the sulfur concentration of the fuel is detected based on the signal from the switch 34.
  • the detection of the sulfur concentration of a fuel for example, it is also possible to adopt a method in which a sensor for detecting the sulfur concentration of the fuel is provided in a fuel tank of the vehicle, and the detection is performed based on a signal output from the sensor.
  • the SOx deposit amount is estimated based on a sulfur concentration less than the rated value.
  • the SOx deposit amount is estimated based on a sulfur concentration equal to or more than the rated value. The SOx deposit amount thus estimated does not become a value excessively deviated to the rich side with respect to the actual SOx deposit amount even if a fuel with a sulfur concentration that is equal to or more than the rated value is used.
  • the estimated SOx deposit amount can have the value that is the same as A2 or close thereto. Therefore, during the SOx poisoning recovery control, it does not occur that the air-fuel ratio Blof exhaust that is controlled corresponding to the estimated SOx deposit amount A1 does not excessively deviate to the rich side with respect to the optimal value B2 for the air-fuel ratio of exhaust, which corresponds to the actual SOx deposit amount A2. Thus, it is possible to inhibit the HC concentration in exhaust from becoming high as a result of the deviation, thereby inhibiting the generation of white smoke.
  • the air-fuel ratio of exhaust may be corrected during the SOx poisoning recovery control based on the sulfur concentration.
  • the estimation of the SOx deposit amount is performed assuming that the sulfur concentration of the fuel is less than the rated value.
  • the air-fuel ratio is corrected depending on the sulfur concentration of the fuel. For example, when the sulfur concentration of the fuel is higher than the rated value, the estimated SOx deposit amount becomes smaller than the actual SOx deposit amount.
  • the air-fuel ratio of exhaust which is controlled based on the estimated SOx deposit amount during the SOx poisoning recovery control, is corrected to the lean side depending on the sulfur concentration of the fuel. Accordingly, the same effect as the above embodiment can be obtained.
  • the concentration of sulfur in the fuel is detected, and the amount of SOx deposited in the NOx catalyst is estimated taking into consideration the concentration of the sulfur in the fuel. Further, the air-fuel ratio of exhaust flowing into the NOx catalyst (16) is changed to a rich side air-fuel ratio depending on a decrease in the estimated SOx deposit amount, whereby the HC concentration of exhaust flowing out from the NOx catalyst (16) is adjusted to a level equal to or less than the permissible HC concentration.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
EP20040021239 2003-09-12 2004-09-07 Système de purification des gaz d'échappement pour un moteur à combustion interne Expired - Lifetime EP1515029B1 (fr)

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JP2003321408 2003-09-12
JP2003321408A JP4241279B2 (ja) 2003-09-12 2003-09-12 内燃機関の排気浄化システム

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EP1515029A2 true EP1515029A2 (fr) 2005-03-16
EP1515029A3 EP1515029A3 (fr) 2006-06-07
EP1515029B1 EP1515029B1 (fr) 2009-02-25

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Publication number Priority date Publication date Assignee Title
FR2905144A1 (fr) * 2006-08-24 2008-02-29 Renault Sas Systeme de desulfuration d'un dispositif de piegeage catalytique d'oxydes d'azote dispose dans la ligne d'echappement d'un moteur a combustion interne
US8375706B2 (en) 2007-09-18 2013-02-19 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification system of an internal combustion engine
EP2955356A4 (fr) * 2013-02-06 2016-03-23 Toyota Motor Co Ltd Dispositif de commande de moteur à combustion interne

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JP4765992B2 (ja) * 2007-04-24 2011-09-07 トヨタ自動車株式会社 内燃機関の排気浄化装置
JP4396760B2 (ja) 2007-11-08 2010-01-13 トヨタ自動車株式会社 内燃機関の排気浄化装置
JP4986915B2 (ja) * 2008-04-16 2012-07-25 三菱ふそうトラック・バス株式会社 排気浄化装置
JP4986973B2 (ja) * 2008-10-23 2012-07-25 三菱ふそうトラック・バス株式会社 排気浄化装置
JP5705676B2 (ja) * 2011-07-27 2015-04-22 株式会社日本自動車部品総合研究所 内燃機関の排気浄化装置

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FR2905144A1 (fr) * 2006-08-24 2008-02-29 Renault Sas Systeme de desulfuration d'un dispositif de piegeage catalytique d'oxydes d'azote dispose dans la ligne d'echappement d'un moteur a combustion interne
US8375706B2 (en) 2007-09-18 2013-02-19 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification system of an internal combustion engine
EP2955356A4 (fr) * 2013-02-06 2016-03-23 Toyota Motor Co Ltd Dispositif de commande de moteur à combustion interne

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DE602004019609D1 (de) 2009-04-09
JP4241279B2 (ja) 2009-03-18
ES2318225T3 (es) 2009-05-01
JP2005090253A (ja) 2005-04-07
EP1515029A3 (fr) 2006-06-07
EP1515029B1 (fr) 2009-02-25

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