JP4095979B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Exhaust gas purification device for internal combustion engine Download PDF

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JP4095979B2
JP4095979B2 JP2004212155A JP2004212155A JP4095979B2 JP 4095979 B2 JP4095979 B2 JP 4095979B2 JP 2004212155 A JP2004212155 A JP 2004212155A JP 2004212155 A JP2004212155 A JP 2004212155A JP 4095979 B2 JP4095979 B2 JP 4095979B2
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internal combustion
temperature
combustion engine
exhaust
exhaust purification
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JP2006029272A (en
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浩之 冨永
剛 橋詰
欣悟 陶山
秀樹 青木
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トヨタ自動車株式会社
株式会社豊田自動織機
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/002Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0821Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with particulate filters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828Exhaust 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
    • F01N3/0842Nitrogen oxides
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00Electrical control of exhaust gas treating apparatus
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/0002Controlling intake air
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/02Circuit arrangements for generating control signals
    • F02D41/021Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/024Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
    • F02D41/0245Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus by increasing temperature of the exhaust gas leaving the engine
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00Adding substances to exhaust gases
    • F01N2610/03Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D9/00Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/02Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning induction conduits
    • F02D2009/0201Arrangements; Control features; Details thereof
    • F02D2009/0222Exhaust gas temperature
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D9/00Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/02Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning induction conduits
    • F02D2009/0201Arrangements; Control features; Details thereof
    • F02D2009/0237Increasing combustion chamber gas temperature
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/02Circuit arrangements for generating control signals
    • F02D41/021Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027Introducing 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
    • F02D41/029Introducing 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 particulate filter
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/02Circuit arrangements for generating control signals
    • F02D41/18Circuit arrangements for generating control signals by measuring intake air flow
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/24Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425Particular ways of programming the data
    • F02D41/2429Methods of calibrating or learning
    • F02D41/2441Methods of calibrating or learning characterised by the learning conditions
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/24Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425Particular ways of programming the data
    • F02D41/2429Methods of calibrating or learning
    • F02D41/2451Methods of calibrating or learning characterised by what is learned or calibrated
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/40Engine management systems

Description

本発明は、内燃機関の排気通路に設けられ、酸化機能を有する排気浄化手段を備えた内燃機関の排気浄化装置に関する。   The present invention relates to an exhaust gas purification apparatus for an internal combustion engine that is provided in an exhaust passage of the internal combustion engine and includes an exhaust gas purification means having an oxidation function.
内燃機関の排気浄化装置においては、排気中の粒子状物質(以下、PMと称する)を捕集するパティキュレートフィルタ(以下、フィルタと称する)や、吸蔵還元型NOx触媒等を、内燃機関の排気通路に設ける場合がある。例えば、フィルタを排気通路に備えた場合、該フィルタに堆積したPMを除去するときに該フィルタを昇温させる必要がある。また、吸蔵還元型NOx触媒を排気通路に備えた場合、該吸蔵還元型NOx触媒に吸蔵されたSOxを還元させるときに該吸蔵還元型NOx触媒を昇温させる必要がある。   In an exhaust gas purification apparatus for an internal combustion engine, a particulate filter (hereinafter referred to as a filter) that collects particulate matter (hereinafter referred to as PM) in exhaust gas, an occlusion reduction type NOx catalyst, or the like is used as an exhaust gas for the internal combustion engine. It may be provided in the passage. For example, when a filter is provided in the exhaust passage, it is necessary to raise the temperature of the filter when removing PM accumulated on the filter. When the NOx storage reduction catalyst is provided in the exhaust passage, it is necessary to raise the temperature of the NOx storage reduction catalyst when reducing the SOx stored in the NOx storage reduction catalyst.
排気浄化手段としてフィルタを排気通路に設けた内燃機関の排気浄化装置において、フィルタの排気浄化能力を再生させるべく該フィルタを昇温させて堆積したPMを除去する場合、(1)高負荷運転領域での通常運転による排気温度の上昇、(2)燃料噴射時期の遅角、(3)膨張行程副燃料噴射およびEGRガスの導入、(4)、膨張行程副燃料噴射および吸気/排気絞り、のうちいずれかの方法を内燃機関の運転状態に応じて選択し、それぞれの方法によってフィルタを昇温させる技術が知られている(例えば、特許文献1参照。)。   In an exhaust gas purification apparatus for an internal combustion engine provided with a filter as an exhaust gas purification means in the exhaust passage, in order to remove the accumulated PM by raising the temperature of the filter so as to regenerate the exhaust gas purification capability of the filter, (1) high load operation region (2) Expansion stroke sub-fuel injection and introduction of EGR gas, (4) Expansion stroke sub-fuel injection and intake / exhaust throttle, A technique is known in which one of the methods is selected according to the operating state of the internal combustion engine, and the temperature of the filter is raised by each method (see, for example, Patent Document 1).
また、排気通路に設けられた排気浄化手段が酸化機能を有している場合においては、該排気浄化手段を昇温させるために、該排気浄化手段より上流側から該排気浄化手段に燃料成分を供給する技術がある。
特開2000−161044号公報 特開2002−285896号公報 特開2002−235589号公報 特開平5−106518号公報
Further, when the exhaust purification means provided in the exhaust passage has an oxidizing function, in order to raise the temperature of the exhaust purification means, the fuel component is supplied to the exhaust purification means from the upstream side of the exhaust purification means. There is technology to supply.
JP 2000-161044 A JP 2002-285896 A JP 2002-235589 A JP-A-5-106518
内燃機関の排気通路に設けられた酸化機能を有する排気浄化手段を備えた内燃機関の排気浄化装置において、排気浄化手段の浄化能力を再生すべく該排気浄化手段を昇温させる場合、例えば、内燃機関での主燃料噴射の後の時期に行われる副燃料噴射や、排気浄化手段より上流側の排気通路への燃料添加によって、排気浄化手段より上流側から該排気浄化手段に燃料成分を供給する。この場合、燃料成分が排気浄化手段において酸化することで発生する酸化熱によって排気浄化手段の温度が上昇する。   In an exhaust gas purification apparatus for an internal combustion engine provided with an exhaust gas purification means having an oxidation function provided in an exhaust passage of the internal combustion engine, when the exhaust gas purification means is heated to regenerate the purification capacity of the exhaust gas purification means, for example, the internal combustion engine The fuel component is supplied to the exhaust purification means from the upstream side of the exhaust purification means by sub fuel injection performed at a timing after the main fuel injection in the engine or by addition of fuel to the exhaust passage upstream of the exhaust purification means. . In this case, the temperature of the exhaust purification unit rises due to the oxidation heat generated by the oxidation of the fuel component in the exhaust purification unit.
しかしながら、内燃機関の運転状態によっては、排気浄化手段の浄化能力を再生することが可能となる目標温度に該排気浄化手段を昇温させるのに十分な量の燃料成分を排気浄化手段に供給するのが困難な場合がある。例えば、内燃機関の機関負荷が高くなるほど気筒内温度や排気温度が高くなる。そのため、副燃料噴射によって噴射された燃料もしくは排気通路へ添加された燃料が、気筒内もしくは排気通路で燃焼してしまい、その結果、排気浄化手段に十分な量の燃料成分が供給されない虞がある。   However, depending on the operating state of the internal combustion engine, a sufficient amount of fuel component is supplied to the exhaust purification unit to raise the temperature of the exhaust purification unit to a target temperature at which the purification capability of the exhaust purification unit can be regenerated. It can be difficult. For example, the higher the engine load of the internal combustion engine, the higher the in-cylinder temperature and the exhaust temperature. Therefore, the fuel injected by the auxiliary fuel injection or the fuel added to the exhaust passage burns in the cylinder or in the exhaust passage, and as a result, a sufficient amount of fuel component may not be supplied to the exhaust purification means. .
本発明は、上記問題に鑑みてなされたものであって、内燃機関の排気浄化装置において、内燃機関の排気通路に設けられた排気浄化手段をより広範囲の運転状態で目標温度に昇温させることを可能とすることで、排気浄化手段の浄化能力をより好適に再生させること
が可能な技術を提供することを課題とする。
The present invention has been made in view of the above problems, and in an exhaust gas purification apparatus for an internal combustion engine, the exhaust gas purification means provided in the exhaust passage of the internal combustion engine is heated to a target temperature in a wider range of operating conditions. It is an object of the present invention to provide a technique capable of more suitably regenerating the purification ability of the exhaust gas purification means.
本発明は、内燃機関の排気通路に設けられた酸化機能を有する排気浄化手段の排気浄化能力を再生すべく該排気浄化手段を目標温度に昇温させるときに、排気浄化手段に供給される燃料成分量を制御することで該排気浄化手段を昇温させるか、もしくは、排気浄化手段への燃料成分の供給を禁止し内燃機関の吸入空気量を制御することで該排気浄化手段を昇温させるかを、内燃機関の運転状態に応じて切り換えるものである。   The present invention relates to a fuel supplied to an exhaust purification means when the exhaust purification means is heated to a target temperature in order to regenerate the exhaust purification ability of the exhaust purification means having an oxidation function provided in an exhaust passage of an internal combustion engine. The exhaust purification unit is heated by controlling the component amount, or the exhaust purification unit is heated by prohibiting the supply of the fuel component to the exhaust purification unit and controlling the intake air amount of the internal combustion engine. Is switched according to the operating state of the internal combustion engine.
より詳しくは、本発明に係る内燃機関の排気浄化装置は、
内燃機関の排気通路に設けられた酸化機能を有する排気浄化手段と、
該排気浄化手段より上流側から該排気浄化手段に燃料成分を供給する燃料成分供給手段と、
前記内燃機関の吸入空気量を制御する吸入空気量制御手段と、を備え、
前記排気浄化手段の排気浄化能力を再生すべく前記排気浄化手段を目標温度に昇温させる昇温条件が成立しているときに、前記内燃機関の機関負荷が規定機関負荷より低い場合は、前記燃料成分供給手段から前記排気浄化手段に供給される燃料成分量を制御することで前記排気浄化手段の温度を前記目標温度に上昇または維持させると共に、前記吸入空気量制御手段によって前記内燃機関の吸入空気量を該内燃機関の機関回転数および該内燃機関の機関負荷から定められる吸入空気量に制御し、
前記昇温条件が成立しているときに、前記内燃機関の機関負荷が前記規定機関負荷以上の場合は、前記燃料成分供給手段からの燃料成分の供給を禁止すると共に、前記吸入空気量制御手段によって前記内燃機関の吸入空気量を制御することで前記排気浄化手段の温度を前記目標温度に上昇または維持させることを特徴とする。
More specifically, the exhaust gas purification apparatus for an internal combustion engine according to the present invention is
Exhaust purification means having an oxidation function provided in the exhaust passage of the internal combustion engine;
Fuel component supply means for supplying a fuel component to the exhaust purification means from the upstream side of the exhaust purification means;
An intake air amount control means for controlling the intake air amount of the internal combustion engine,
When the engine load of the internal combustion engine is lower than a specified engine load when a temperature raising condition for raising the temperature of the exhaust purification unit to a target temperature is established to regenerate the exhaust purification capability of the exhaust purification unit, By controlling the amount of fuel component supplied from the fuel component supply means to the exhaust purification means, the temperature of the exhaust purification means is raised or maintained at the target temperature, and the intake air amount control means is used to intake the internal combustion engine. Controlling the amount of air to an intake air amount determined from the engine speed of the internal combustion engine and the engine load of the internal combustion engine;
When the temperature increase condition is satisfied and the engine load of the internal combustion engine is equal to or greater than the specified engine load, the supply of the fuel component from the fuel component supply means is prohibited and the intake air amount control means By controlling the intake air amount of the internal combustion engine by the above, the temperature of the exhaust purification means is raised or maintained at the target temperature.
本発明に係る排気浄化手段としては、酸化触媒または吸蔵還元型NOx触媒を担持したフィルタや、吸蔵還元型NOx触媒等が例示出来る。   Examples of the exhaust purification means according to the present invention include a filter carrying an oxidation catalyst or a NOx storage reduction catalyst, an NOx storage reduction catalyst, and the like.
また、本発明に係る燃料成分供給手段は、内燃機関の気筒内において主燃料噴射よりも後の時期であって膨張行程または排気行程で副燃料噴射を実行することによって排気浄化手段に燃料成分を供給するものであっても良く、また、排気浄化手段より上流側の排気通路に燃料成分を添加することによって排気浄化手段に燃料成分を供給するものであっても良い。   The fuel component supply means according to the present invention performs fuel injection to the exhaust purification means by executing sub fuel injection in the expansion stroke or exhaust stroke at a time after the main fuel injection in the cylinder of the internal combustion engine. The fuel component may be supplied, or the fuel component may be supplied to the exhaust purification unit by adding the fuel component to the exhaust passage upstream of the exhaust purification unit.
昇温条件は排気浄化手段の種類等に応じて変更される。例えば、排気浄化手段がフィルタの場合は、昇温条件を、フィルタに堆積したPMの除去を実行する条件としても良く、また、排気浄化手段が吸蔵還元型NOx触媒の場合は、昇温条件を、吸蔵還元型NOx触媒に吸蔵されたSOxの還元を実行する条件としても良い。また、目標温度も昇温の目的に応じて変更される。   The temperature raising condition is changed according to the type of the exhaust gas purification means. For example, when the exhaust purification means is a filter, the temperature raising condition may be a condition for removing PM accumulated on the filter. When the exhaust purification means is an NOx storage reduction catalyst, the temperature raising condition may be Alternatively, the condition for executing the reduction of SOx stored in the NOx storage reduction catalyst may be used. The target temperature is also changed according to the purpose of raising the temperature.
本発明において、排気浄化手段を目標温度に昇温させる昇温条件が成立しているときに、内燃機関の機関負荷が規定機関負荷より低い場合は、燃料成分供給手段から排気浄化手段に供給される燃料成分量を制御することで排気浄化手段の温度を前記目標温度に上昇または維持させる。また、このとき、吸入空気量制御手段は、内燃機関の吸入空気量を該内燃機関の機関回転数および該内燃機関の機関負荷から定められる吸入空気量に制御される。   In the present invention, when the temperature raising condition for raising the temperature of the exhaust purification means to the target temperature is established, if the engine load of the internal combustion engine is lower than the specified engine load, the fuel component supply means supplies the exhaust purification means to the exhaust purification means. The temperature of the exhaust purification means is raised or maintained at the target temperature by controlling the amount of fuel component to be controlled. At this time, the intake air amount control means controls the intake air amount of the internal combustion engine to an intake air amount determined from the engine speed of the internal combustion engine and the engine load of the internal combustion engine.
ところが、上述したように、内燃機関の機関負荷が高くなるほど気筒内温度や排気温度は高くなるため、高負荷領域では、排気浄化手段より上流側から燃料成分供給手段によって供給される燃料成分が気筒内もしくは排気通路内において燃焼してしまう虞がある。   However, as described above, the higher the engine load of the internal combustion engine, the higher the in-cylinder temperature and the exhaust temperature. Therefore, in the high load region, the fuel component supplied by the fuel component supply means from the upstream side of the exhaust purification means is the cylinder. There is a risk of burning inside or in the exhaust passage.
そこで、本発明においては、排気浄化手段を目標温度に昇温させる昇温条件が成立しているときに、内燃機関の機関負荷が規定機関負荷以上の場合は、燃料成分供給手段からの燃料成分の供給を禁止する。そして、吸入空気量制御手段によって内燃機関の吸入空気量を制御することで排気浄化手段の温度を前記目標温度に上昇または維持させる。   Therefore, in the present invention, when the temperature increase condition for raising the temperature of the exhaust gas purification means to the target temperature is satisfied, if the engine load of the internal combustion engine is equal to or higher than the specified engine load, the fuel component from the fuel component supply means Prohibit the supply of Then, the intake air amount control means controls the intake air amount of the internal combustion engine to raise or maintain the temperature of the exhaust purification means at the target temperature.
ここで、規定機関負荷とは、気筒内もしくは排気温度が高温となり、燃料成分供給手段から供給された燃料成分が気筒内もしくは排気通路内において燃焼してしまう機関負荷の閾値であってもよい。   Here, the specified engine load may be a threshold value of an engine load at which the fuel component supplied from the fuel component supply means burns in the cylinder or the exhaust passage when the temperature in the cylinder or the exhaust gas becomes high.
排気浄化手段へ燃料成分を供給しなくても、吸入空気量を低下させることによって排気の流量を減少させれば、排気の温度を高くすることが出来、それに伴って排気浄化手段を昇温させることが出来る。そして、内燃機関の機関負荷がある程度高い場合は、吸入空気量の制御のみによって排気浄化手段の温度を目標温度にすることが出来る。また、内燃機関の機関負荷が規定機関負荷以上の場合には燃料成分の供給を禁止することによって、気筒内もしくは排気通路内で該燃料成分が燃焼することで排気の温度が過剰に上昇することを抑制することが出来る。   Even if the fuel component is not supplied to the exhaust purification means, if the flow rate of the exhaust gas is reduced by reducing the amount of intake air, the temperature of the exhaust can be raised, and the temperature of the exhaust purification means is raised accordingly. I can do it. When the engine load of the internal combustion engine is high to some extent, the temperature of the exhaust purification unit can be set to the target temperature only by controlling the intake air amount. Further, when the engine load of the internal combustion engine is equal to or higher than the specified engine load, the fuel component is prohibited from being supplied, and the fuel component burns in the cylinder or the exhaust passage, so that the exhaust temperature rises excessively. Can be suppressed.
従って、本発明によれば、内燃機関の機関負荷が高い場合であっても低い場合であっても、排気浄化手段の温度を目標温度に上昇または維持させることが出来る。即ち、より広範囲の運転状態で排気浄化手段を目標温度に昇温させることが可能となり、以って、排気浄化手段の浄化能力をより好適に再生することが可能となる。   Therefore, according to the present invention, it is possible to raise or maintain the temperature of the exhaust gas purification means to the target temperature regardless of whether the engine load of the internal combustion engine is high or low. That is, it is possible to raise the temperature of the exhaust gas purification means to the target temperature in a wider range of operating conditions, and thus it is possible to more suitably regenerate the purification capacity of the exhaust gas purification means.
また、内燃機関の気筒内において主燃料噴射よりも後の時期であって膨張行程または排気行程で副燃料噴射を実行することで、排気浄化手段より上流側から該排気浄化手段に燃料成分を供給する場合、内燃機関の機関回転数が高くなるほど1回の燃焼サイクルにかかる時間が短くなるため、1回の燃焼サイクル毎に実行可能な副燃料噴射の回数が少なくなる。そのため、高回転運転領域では、副燃料噴射によっては、排気浄化手段を目標温度に昇温させるのに十分な量の燃料成分を供給することが困難な場合がある。   In addition, the fuel component is supplied to the exhaust purification means from the upstream side of the exhaust purification means by executing the auxiliary fuel injection in the expansion stroke or the exhaust stroke in the cylinder of the internal combustion engine after the main fuel injection. In this case, since the time required for one combustion cycle is shortened as the engine speed of the internal combustion engine increases, the number of sub fuel injections that can be performed for each combustion cycle decreases. Therefore, in the high speed operation region, depending on the auxiliary fuel injection, it may be difficult to supply an amount of fuel component sufficient to raise the temperature of the exhaust purification unit to the target temperature.
そこで、本発明において、燃料成分供給手段が、内燃機関の気筒内において主燃料噴射よりも後の時期であって膨張行程または排気行程で副燃料噴射を実行することで、排気浄化手段より上流側から該排気浄化手段に燃料成分を供給するものである場合は、前記昇温条件が成立しているときに前記内燃機関の機関負荷が規定機関負荷より低い場合であっても、内燃機関の機関回転数が規定機関回転数以上の場合は、燃料成分供給手段からの燃料成分の供給を禁止する。そして、吸入空気量制御手段によって内燃機関の吸入空気量を制御することで排気浄化手段の温度を目標温度に上昇または維持させるのが好ましい。   Therefore, in the present invention, the fuel component supply means performs the auxiliary fuel injection in the expansion stroke or the exhaust stroke at a time later than the main fuel injection in the cylinder of the internal combustion engine, so that the upstream side of the exhaust purification means. When the fuel component is supplied from the engine to the exhaust gas purification means, even if the engine load of the internal combustion engine is lower than the specified engine load when the temperature raising condition is satisfied, the engine of the internal combustion engine When the rotational speed is equal to or higher than the specified engine rotational speed, the supply of the fuel component from the fuel component supply means is prohibited. It is preferable to control the intake air amount of the internal combustion engine by the intake air amount control means to raise or maintain the temperature of the exhaust purification means to the target temperature.
ここで、規定機関回転数とは、予め定められた機関回転数であって、排気浄化手段を目標温度に昇温させるのに十分な量の燃料成分を供給するのが可能となる副燃料噴射の回数を確保するのが困難となる機関回転数の閾値としても良い。   Here, the prescribed engine speed is a predetermined engine speed, and a sub fuel injection that can supply a sufficient amount of fuel components to raise the temperature of the exhaust gas purification means to the target temperature. It is good also as a threshold value of the engine speed which makes it difficult to secure the number of times.
本発明によれば、排気浄化手段への燃料供給が副燃料噴射によって行われる場合において、内燃機関の機関回転数が高い場合であっても、排気浄化手段をより確実に目標温度に昇温させることが出来る。即ち、より広範囲の運転状態で排気浄化手段を目標温度に昇温させることが可能となり、以って、排気浄化手段の浄化能力をより好適に再生することが可能となる。   According to the present invention, when the fuel supply to the exhaust purification unit is performed by sub fuel injection, the exhaust purification unit is more reliably heated to the target temperature even when the engine speed of the internal combustion engine is high. I can do it. That is, it is possible to raise the temperature of the exhaust gas purification means to the target temperature in a wider range of operating conditions, and thus it is possible to more suitably regenerate the purification capacity of the exhaust gas purification means.
また、内燃機関においては、機関回転数が高くなるほど、気筒内壁面とピストンとの間等におけるフリクションが増大する。そのため、機関回転数が高いときであっても機関回
転数が低いときと同様のトルクを発生させるために、機関負荷を同様とした場合、機関回転数が高くなるほど主燃料噴射における燃料噴射量を増大させている。しかしながら、このような燃料噴射量の制御を行った場合、機関回転数が高くなるほど、気筒内温度および排気温度が主燃料噴射における燃料噴射量の増大分だけ高くなる虞がある。その結果、機関回転数が高くなるほど、燃料成分供給手段から供給された燃料成分が気筒内もしくは排気通路内において燃焼し易くなる虞がある。
In an internal combustion engine, the friction between the cylinder inner wall surface and the piston increases as the engine speed increases. Therefore, in order to generate the same torque as when the engine speed is low even when the engine speed is high, when the engine load is the same, the fuel injection amount in the main fuel injection becomes higher as the engine speed becomes higher. It is increasing. However, when such fuel injection amount control is performed, the higher the engine speed, the higher the in-cylinder temperature and the exhaust temperature may be increased by the increase in the fuel injection amount in the main fuel injection. As a result, as the engine speed increases, the fuel component supplied from the fuel component supply means may be easily burned in the cylinder or the exhaust passage.
そこで、本発明においては、前記規定機関負荷を、前記昇温条件が成立しているときの内燃機関の機関回転数が高いほど低い値に設定するのが好ましい。   Therefore, in the present invention, it is preferable that the prescribed engine load is set to a lower value as the engine speed of the internal combustion engine is higher when the temperature increase condition is satisfied.
規定機関負荷をこのように設定することで、燃料成分が気筒内もしくは排気通路内において燃焼し易いときに燃料成分供給手段による燃料供給によって排気浄化手段の昇温が行われるのを抑制することが出来る。即ち、より広範囲の運転状態で排気浄化手段をより確実に目標温度に昇温させることが可能となる。   By setting the specified engine load in this way, it is possible to suppress the temperature increase of the exhaust purification unit due to the fuel supply by the fuel component supply unit when the fuel component easily burns in the cylinder or the exhaust passage. I can do it. That is, it becomes possible to reliably raise the temperature of the exhaust gas purification means to the target temperature in a wider range of operating conditions.
本発明において、燃料成分供給手段からの燃料成分の供給が実行されていない状態における、内燃機関の吸入空気量と排気浄化手段の温度との関係を学習する学習手段をさらに備えた場合、昇温条件が成立しているときに、内燃機関の運転状態が、燃料成分供給手段から排気浄化手段に供給される燃料成分量を制御することで該排気浄化手段を目標温度に昇温させる運転領域(以下、燃料成分量制御領域と称する)から、吸入空気量制御手段によって内燃機関の吸入空気量を制御することで排気浄化手段を目標温度に昇温させる運転領域(以下、吸入空気量制御領域と称する)に移行したときは、燃料成分供給手段からの燃料成分の供給を停止した後、排気浄化手段の温度が定常状態となってから、学習手段によって、内燃機関の吸入空気量と排気浄化手段の温度との関係の学習を実行する。そして、この学習手段によって学習された内燃機関の吸入空気量と排気浄化手段の温度との関係に基づいて、排気浄化手段の温度を目標温度とすべく吸入空気量制御手段によって内燃機関の吸入空気量を制御するのが好ましい。 In the present invention, when further comprising learning means for learning the relationship between the intake air amount of the internal combustion engine and the temperature of the exhaust purification means when the supply of the fuel component from the fuel component supply means is not executed, When the condition is satisfied, the operating state of the internal combustion engine is an operating region in which the exhaust purification means is heated to a target temperature by controlling the amount of fuel component supplied from the fuel component supply means to the exhaust purification means ( Hereinafter, from the fuel component amount control region), an operation region (hereinafter referred to as an intake air amount control region) in which the exhaust purification unit is heated to a target temperature by controlling the intake air amount of the internal combustion engine by the intake air amount control unit. ), After the supply of the fuel component from the fuel component supply means is stopped and the temperature of the exhaust purification means becomes a steady state, the learning means takes the intake air amount of the internal combustion engine. It executes learning of a relationship between the temperature of the exhaust gas purification means. Then, based on the relationship between the intake air amount of the internal combustion engine learned by the learning means and the temperature of the exhaust purification means, the intake air amount of the internal combustion engine is controlled by the intake air amount control means so that the temperature of the exhaust purification means becomes the target temperature. It is preferred to control the amount.
昇温条件が成立しているときに、内燃機関の運転状態が燃料成分量制御領域から吸入空気量制御領域に移行した場合、燃料成分供給手段からの排気浄化手段への燃料供給が停止される。そのため、排気浄化手段の温度は低下し始めることになる。このとき、排気浄化手段の温度が低下している最中に内燃機関の吸入空気量と排気浄化手段の温度との関係を学習手段が学習すると実際の関係とずれが生じる虞がある。   If the operating condition of the internal combustion engine shifts from the fuel component amount control region to the intake air amount control region when the temperature raising condition is satisfied, the fuel supply from the fuel component supply unit to the exhaust purification unit is stopped. . For this reason, the temperature of the exhaust gas purification means starts to decrease. At this time, if the learning means learns the relationship between the intake air amount of the internal combustion engine and the temperature of the exhaust purification means while the temperature of the exhaust purification means is decreasing, a deviation from the actual relationship may occur.
そこで、本発明では、吸入空気量と排気浄化手段の温度との関係を学習手段によって学習する場合、学習する時点での吸入空気量に対応した温度にまで排気浄化手段の温度が低下してから、即ち、排気浄化手段の温度が定常状態となってから学習を実行する。尚、ここでは、排気浄化手段の単位時間当りの温度変化量が予め定められた規定量以下となったときに排気浄化手段の温度が定常状態となったと判断しても良い。   Therefore, in the present invention, when the learning means learns the relationship between the amount of intake air and the temperature of the exhaust purification means, after the temperature of the exhaust purification means has decreased to a temperature corresponding to the amount of intake air at the time of learning. That is, the learning is executed after the temperature of the exhaust gas purifying means reaches a steady state. Here, it may be determined that the temperature of the exhaust purification means has reached a steady state when the temperature change amount per unit time of the exhaust purification means has become equal to or less than a predetermined amount.
このように、排気浄化手段の温度が定常状態にあるときに吸入空気量と排気浄化手段の温度との関係を学習し、この学習した関係に基づいて排気浄化手段の温度を目標温度とすべく吸入空気量を制御することで、昇温条件が成立しているときに、内燃機関の運転状態が低負荷から高負荷に変化した場合であっても、排気浄化手段の温度をより正確に目標温度に制御することが出来る。   As described above, when the temperature of the exhaust gas purification means is in a steady state, the relationship between the intake air amount and the temperature of the exhaust gas purification means is learned, and the temperature of the exhaust gas purification means should be set to the target temperature based on the learned relationship. By controlling the intake air amount, the temperature of the exhaust gas purification means can be more accurately targeted even when the operating condition of the internal combustion engine changes from low load to high load when the temperature rise condition is satisfied. Temperature can be controlled.
本発明に係る内燃機関の排気浄化装置によれば、内燃機関の排気通路に設けられた排気浄化手段を、より広範囲の運転状態で目標温度に昇温させることが出来、以って、排気浄化手段の浄化能力をより好適に再生することが可能となる。   According to the exhaust gas purification apparatus for an internal combustion engine according to the present invention, the exhaust gas purification means provided in the exhaust passage of the internal combustion engine can be raised to the target temperature in a wider range of operating conditions, and thus the exhaust gas purification device. It becomes possible to regenerate the purification ability of the means more suitably.
以下、本発明に係る内燃機関の排気浄化装置の具体的な実施の形態について図面に基づいて説明する。   Hereinafter, specific embodiments of an exhaust emission control device for an internal combustion engine according to the present invention will be described with reference to the drawings.
<内燃機関とその吸排気系および制御系の概略構成>
ここでは、本発明を車両駆動用のディーゼル機関に適用した場合を例に挙げて説明する。図1は、本実施例に係る内燃機関とその吸排気系の概略構成を示す図である。
<Schematic configuration of internal combustion engine and its intake / exhaust system and control system>
Here, the case where the present invention is applied to a diesel engine for driving a vehicle will be described as an example. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine and its intake / exhaust system according to the present embodiment.
内燃機関1は車両駆動用のディーゼル機関である。この内燃機関1には、吸気通路4と排気通路2が接続されている。吸気通路4には、エアフローメータ11とスロットル弁8とが設けられている。一方、排気通路2には、排気に含まれる煤等のPMを捕集するパティキュレートフィルタ3(以下、単にフィルタ3と称する)が設けられている。このフィルタ3には酸化触媒が担持されている。尚、フィルタ3には酸化触媒の代わりに吸蔵還元型NOx触媒が担持されていても良い。また、フィルタ3に触媒を担持させず該フィルタより上流側の排気通路2に酸化触媒等を配置した構成としても良い。   The internal combustion engine 1 is a diesel engine for driving a vehicle. An intake passage 4 and an exhaust passage 2 are connected to the internal combustion engine 1. An air flow meter 11 and a throttle valve 8 are provided in the intake passage 4. On the other hand, the exhaust passage 2 is provided with a particulate filter 3 (hereinafter simply referred to as a filter 3) that collects PM such as soot contained in the exhaust. The filter 3 carries an oxidation catalyst. The filter 3 may carry an NOx storage reduction catalyst instead of the oxidation catalyst. Further, the catalyst may not be supported on the filter 3 and an oxidation catalyst or the like may be disposed in the exhaust passage 2 upstream of the filter.
フィルタ3より上流側の排気通路2には、排気中に燃料を添加する燃料添加弁5が設けられている。フィルタ3より下流側の排気通路2には、該排気通路2を流通する排気の温度に対応した電気信号を出力する排気温度センサ7が設けられている。   A fuel addition valve 5 is provided in the exhaust passage 2 upstream of the filter 3 to add fuel into the exhaust. An exhaust temperature sensor 7 that outputs an electrical signal corresponding to the temperature of the exhaust gas flowing through the exhaust passage 2 is provided in the exhaust passage 2 downstream of the filter 3.
以上述べたように構成された内燃機関1には、この内燃機関1を制御するための電子制御ユニット(ECU)10が併設されている。このECU10は、内燃機関1の運転条件や運転者の要求に応じて内燃機関1の運転状態を制御するユニットである。ECU10は、エアフローメータ11や、排気温度センサ7、さらに、内燃機関1のクランク角に対応した電気信号を出力するクランクポジションセンサ6、アクセル開度に対応した電気信号を出力するアクセル開度センサ9等の各種センサと電気的に接続されており、これらの出力信号がECU10に入力される。そして、ECU10は、クランクポジションセンサ6の出力値から内燃機関1の機関回転数を導出し、アクセル開度センサ9の出力値から内燃機関1の機関負荷を導出する。また、ECU10は、排気温度センサ7の出力値からフィルタ3の温度を推定する。また、ECU10は、スロットル弁8や燃料添加弁5、内燃機関1の燃料噴射弁等と電気的に接続されており、これらを制御することが可能となっている。   The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU) 10 for controlling the internal combustion engine 1. The ECU 10 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver. The ECU 10 includes an air flow meter 11, an exhaust gas temperature sensor 7, a crank position sensor 6 that outputs an electric signal corresponding to the crank angle of the internal combustion engine 1, and an accelerator opening sensor 9 that outputs an electric signal corresponding to the accelerator opening. These output signals are input to the ECU 10. The ECU 10 derives the engine speed of the internal combustion engine 1 from the output value of the crank position sensor 6, and derives the engine load of the internal combustion engine 1 from the output value of the accelerator opening sensor 9. Further, the ECU 10 estimates the temperature of the filter 3 from the output value of the exhaust temperature sensor 7. The ECU 10 is electrically connected to the throttle valve 8, the fuel addition valve 5, the fuel injection valve of the internal combustion engine 1, and the like, and can control them.
<フィルタ昇温制御>
本実施例において、フィルタ3にPMが堆積すると該フィルタ3の排気浄化能力が低下することになる。そのため、本実施例では、フィルタ3に規定堆積量以上のPMが堆積した場合、フィルタ3に堆積したPMを酸化・除去して該フィルタ3の排気浄化能力を再生させるべく該フィルタ3を目標温度に昇温させるフィルタ昇温制御が実行される。ここで、規定堆積量とは、PMが酸化するときに発生する熱によってフィルタ3が過昇温する虞があるPMの堆積量よりも少ない量であって、実験等によって予め定められた量である。また、目標温度とは、堆積したPMが酸化し除去される温度である。尚、予め定められた規定時間毎、もしくは、予め定められた規定走行距離毎にフィルタ昇温制御を実行しても良い。
<Filter temperature rise control>
In this embodiment, when PM accumulates on the filter 3, the exhaust gas purification capacity of the filter 3 decreases. For this reason, in this embodiment, when PM equal to or more than the specified accumulation amount is accumulated on the filter 3, the filter 3 is set to the target temperature in order to oxidize and remove the PM accumulated on the filter 3 to regenerate the exhaust gas purification ability of the filter 3. The filter temperature raising control for raising the temperature is executed. Here, the prescribed accumulation amount is an amount that is smaller than the accumulation amount of PM that may cause the filter 3 to overheat due to heat generated when the PM is oxidized, and is an amount that is determined in advance by experiments or the like. is there. The target temperature is a temperature at which deposited PM is oxidized and removed. Note that the filter temperature increase control may be executed at predetermined time intervals or at predetermined predetermined travel distances.
ここで、本実施例に係るフィルタ昇温制御ルーチンについて図2に示すフローチャート図に基づいて説明する。本ルーチンは、ECU10に予め記憶されており、内燃機関1の運転中、予め定められた制御実行時間毎に繰り返される。   Here, the filter temperature raising control routine according to the present embodiment will be described with reference to the flowchart shown in FIG. This routine is stored in advance in the ECU 10 and is repeated at predetermined control execution times during the operation of the internal combustion engine 1.
本ルーチンでは、先ず、ECU10は、S101において、フィルタ昇温制御の実行条件が成立しているか否かを判別する。S101において、肯定判定された場合、ECU10はS102に進み、否定判定された場合、ECU10は本ルーチンの実行を終了する。   In this routine, first, in S101, the ECU 10 determines whether or not an execution condition for the filter temperature increase control is satisfied. If an affirmative determination is made in S101, the ECU 10 proceeds to S102, and if a negative determination is made, the ECU 10 ends the execution of this routine.
S102に進んだECU10は、現時点での内燃機関1の機関負荷が規定機関負荷以上であるか否かを判別する。   The ECU 10 having proceeded to S102 determines whether or not the current engine load of the internal combustion engine 1 is equal to or greater than the specified engine load.
ここで、規定機関負荷とは、フィルタ3より上流側の排気通路2内を流れる排気の温度が、燃料添加弁5から燃料を添加した場合に該燃料が排気通路2内で燃焼してしまうほど高温となっていると判断出来る機関負荷の閾値である。尚、内燃機関1の機関負荷を同様とした場合、内燃機関1の機関回転数が高いほど、主燃料噴射による燃料噴射量が増大されるため気筒2内の温度および排気温度が高くなる虞がある。そのため、本実施例においては、規定機関負荷は、現時点での内燃機関1の機関回転数が高いほど低い値に設定される。ここでは、内燃機関1の機関回転数と規定機関負荷との関係を定めたマップをECU10に予め記憶させておいても良い。S102において、肯定判定された場合、ECU10はS103に進み、否定判定された場合、ECU10はS104に進む。   Here, the specified engine load is such that the temperature of the exhaust gas flowing in the exhaust passage 2 upstream from the filter 3 burns in the exhaust passage 2 when fuel is added from the fuel addition valve 5. This is the engine load threshold that can be determined to be high. If the engine load of the internal combustion engine 1 is the same, the higher the engine speed of the internal combustion engine 1, the higher the fuel injection amount by the main fuel injection, and thus the temperature in the cylinder 2 and the exhaust gas temperature may increase. is there. Therefore, in this embodiment, the prescribed engine load is set to a lower value as the engine speed of the internal combustion engine 1 at the present time is higher. Here, a map that defines the relationship between the engine speed of the internal combustion engine 1 and the prescribed engine load may be stored in the ECU 10 in advance. If an affirmative determination is made in S102, the ECU 10 proceeds to S103, and if a negative determination is made, the ECU 10 proceeds to S104.
S104に進んだECU10は、燃料添加弁5からの燃料添加を実行することでフィルタ3に燃料を供給し、燃料添加量を制御することで、現時点でのフィルタ3の温度が目標温度より低い場合は該フィルタ3を目標温度にまで昇温させ、現時点でのフィルタ3の温度が目標温度である場合はこの目標温度を維持させる。
る。つまり、この場合、燃料添加弁5から燃料が添加されることでフィルタ3に担持された酸化触媒に該燃料が供給される。そして、この燃料が酸化触媒にて酸化することで発生する熱によってフィルタ3が昇温される。尚、S104において、燃料添加弁5からの燃料添加が実行される場合、スロットル弁8の開度は内燃機関1の機関回転数および機関負荷から定められる開度に制御される。このときのスロットル弁8の開度は、通常の運転状態において内燃機関1の機関回転数および機関負荷を同様とした場合とは異なる開度であっても良い。S104において、フィルタ3を目標温度に昇温させた後、ECU10は本ルーチンの実行を終了する。
The ECU 10 that has proceeded to S104 supplies fuel to the filter 3 by executing fuel addition from the fuel addition valve 5 and controls the amount of fuel addition, so that the current temperature of the filter 3 is lower than the target temperature. Raises the temperature of the filter 3 to the target temperature, and maintains the target temperature when the current temperature of the filter 3 is the target temperature.
The In other words, in this case, the fuel is supplied from the fuel addition valve 5 to the oxidation catalyst supported by the filter 3. Then, the temperature of the filter 3 is raised by the heat generated when the fuel is oxidized by the oxidation catalyst. In S104, when fuel addition from the fuel addition valve 5 is executed, the opening of the throttle valve 8 is controlled to an opening determined from the engine speed of the internal combustion engine 1 and the engine load. The opening degree of the throttle valve 8 at this time may be an opening degree different from the case where the engine speed and the engine load of the internal combustion engine 1 are the same in the normal operation state. In S104, after raising the temperature of the filter 3 to the target temperature, the ECU 10 ends the execution of this routine.
一方、S103に進んだECU10は、燃料添加弁5からの燃料添加を禁止すると共に、スロットル弁8の開度を小さくすることで吸入空気量を減少させ、フィルタ3を目標温度に昇温させる。   On the other hand, the ECU 10 proceeding to S103 prohibits fuel addition from the fuel addition valve 5, reduces the amount of intake air by reducing the opening of the throttle valve 8, and raises the temperature of the filter 3 to the target temperature.
上述したように、機関負荷が規定機関負荷以上のときに燃料添加弁5から燃料を添加すると該燃料が排気通路2内で燃焼してしまう。そのため、燃料添加弁5からの燃料添加では、フィルタ3の温度を目標温度とするのに十分な燃料をフィルタ3に担持された酸化触媒に供給するのが困難となる虞がある。そこで、このS103では、スロットル弁8の開度を制御する、即ち吸入空気量を制御することで、現時点でのフィルタ3の温度が目標温度より低い場合は該フィルタ3を目標温度にまで昇温させ、現時点でのフィルタ3の温度が目標温度である場合はこの目標温度を維持させる。   As described above, when fuel is added from the fuel addition valve 5 when the engine load is equal to or higher than the specified engine load, the fuel burns in the exhaust passage 2. Therefore, in the fuel addition from the fuel addition valve 5, it may be difficult to supply sufficient fuel to the oxidation catalyst supported on the filter 3 to set the temperature of the filter 3 to the target temperature. Therefore, in S103, by controlling the opening degree of the throttle valve 8, that is, controlling the intake air amount, if the current temperature of the filter 3 is lower than the target temperature, the temperature of the filter 3 is raised to the target temperature. If the current temperature of the filter 3 is the target temperature, the target temperature is maintained.
この場合、吸入空気量を減少させることで排気温度が上昇し、排気温度の上昇に伴ってフィルタ3が昇温されることになる。尚、この場合、スロットル弁8の開度を変更する前に、燃料添加弁5からの燃料添加が行われていない状態におけるスロットル弁8の開度とフィルタ3の温度との関係を学習し、この学習した関係に基づいてスロットル弁8の開度を制御する。S103において、フィルタ3を目標温度に昇温させた後、ECU10は本ルーチンの実行を終了する。   In this case, the exhaust air temperature is increased by reducing the intake air amount, and the temperature of the filter 3 is increased as the exhaust air temperature increases. In this case, before changing the opening degree of the throttle valve 8, the relationship between the opening degree of the throttle valve 8 and the temperature of the filter 3 in a state where fuel addition from the fuel addition valve 5 is not performed is learned. Based on the learned relationship, the opening degree of the throttle valve 8 is controlled. In S103, after raising the temperature of the filter 3 to the target temperature, the ECU 10 ends the execution of this routine.
以上説明した制御ルーチンによれば、内燃機関1の機関負荷が高い場合であっても低い
場合であっても、フィルタ3を目標温度に昇温することが出来る。即ち、より広範囲の運転状態でフィルタ3を目標温度に昇温させることが可能となるため、堆積したPMの酸化・除去をより広範囲の運転状態で実行することが出来る。また、内燃機関1の機関負荷が規定機関負荷以上の場合には燃料添加弁5からの燃料添加を禁止することによって、排気通路2内で燃料が燃焼することで排気の温度が過剰に上昇することを抑制することが出来る。このように、本実施例によれば、フィルタ3の浄化能力をより好適に再生することが可能となる。
According to the control routine described above, the filter 3 can be raised to the target temperature regardless of whether the engine load of the internal combustion engine 1 is high or low. That is, the filter 3 can be raised to the target temperature in a wider range of operating conditions, so that the deposited PM can be oxidized and removed in a wider range of operating conditions. In addition, when the engine load of the internal combustion engine 1 is equal to or higher than the specified engine load, the fuel addition from the fuel addition valve 5 is prohibited, so that the fuel burns in the exhaust passage 2 and the exhaust temperature excessively increases. This can be suppressed. Thus, according to the present embodiment, it is possible to more suitably regenerate the purification ability of the filter 3.
尚、上記制御ルーチンにおいては、フィルタ3を昇温させるべく該フィルタ3に燃料を供給する場合、排気中に燃料添加弁5から燃料を添加するとしたが、燃料添加弁5からの燃料添加の代わりに、内燃機関1の気筒内において主燃料噴射よりも後の時期であって膨張行程または排気行程で副燃料噴射を実行することで、フィルタ3より上流側から該フィルタ3に燃料を供給しても良い。   In the above control routine, when fuel is supplied to the filter 3 in order to raise the temperature of the filter 3, the fuel is added from the fuel addition valve 5 into the exhaust, but instead of the fuel addition from the fuel addition valve 5. Furthermore, fuel is supplied to the filter 3 from the upstream side of the filter 3 by executing the auxiliary fuel injection in the expansion stroke or the exhaust stroke after the main fuel injection in the cylinder of the internal combustion engine 1. Also good.
また、上記制御ルーチンは、フィルタ3に吸蔵還元型NOx触媒(以下、NOx触媒と称する)を担持した場合において、NOx触媒に吸蔵されたSOxを還元する場合にも適用出来る。この場合、フィルタ昇温条件を、NOx触媒に吸蔵されたSOx量が規定吸蔵量以上となった場合としても良い。また、目標昇温を、NOx触媒に吸蔵されたSOxを還元可能な温度とする。   The above control routine can also be applied to the case where the NOx storage reduction catalyst (hereinafter referred to as NOx catalyst) is carried on the filter 3 and the SOx stored in the NOx catalyst is reduced. In this case, the filter temperature raising condition may be a case where the SOx amount occluded in the NOx catalyst becomes equal to or greater than the specified occlusion amount. The target temperature rise is set to a temperature at which the SOx stored in the NOx catalyst can be reduced.
さらに、フィルタ3の代わりにNOx触媒を配置した場合において、該NOx触媒を昇温させる場合に適用しても良い。   Furthermore, when a NOx catalyst is disposed instead of the filter 3, the present invention may be applied to the case where the temperature of the NOx catalyst is raised.
<スロットル弁開度とフィルタ温度との関係の学習>
次に、フィルタ昇温制御実行中に内燃機関1の機関負荷が規定機関負荷より低い状態から規定機関負荷以上に移行した場合の制御について図3に基づいて説明する。図3は、フィルタ昇温制御実行中における、機関負荷および燃料添加弁5からの燃料添加、フィルタ3の温度、スロットル弁8の開度の関係を示すタイムチャートである。機関負荷における一点鎖線は規定機関負荷を表し、フィルタ温度における一点鎖線は目標温度を表している。
<Learning the relationship between throttle valve opening and filter temperature>
Next, control when the engine load of the internal combustion engine 1 shifts from a state lower than the specified engine load to a specified engine load or higher during execution of the filter temperature increase control will be described with reference to FIG. FIG. 3 is a time chart showing the relationship between the engine load, the fuel addition from the fuel addition valve 5, the temperature of the filter 3, and the opening degree of the throttle valve 8 during execution of the filter temperature increase control. The alternate long and short dash line in the engine load represents the specified engine load, and the alternate long and short dash line in the filter temperature represents the target temperature.
上述したように、フィルタ昇温制御の実行時であって内燃機関1の機関負荷が規定機関負荷より低い場合は、燃料添加弁5からの燃料添加が実行されている。このときに、内燃機関1の機関負荷が規定機関負荷以上に移行した場合、図3に示すように、移行した時点で燃料添加弁5からの燃料添加が停止される。その結果、目標温度に制御されていたフィルタ3の温度が低下し始める。   As described above, when the filter temperature increase control is being executed and the engine load of the internal combustion engine 1 is lower than the specified engine load, fuel addition from the fuel addition valve 5 is being executed. At this time, when the engine load of the internal combustion engine 1 shifts to a specified engine load or more, as shown in FIG. 3, the fuel addition from the fuel addition valve 5 is stopped at the time of the shift. As a result, the temperature of the filter 3 controlled to the target temperature starts to decrease.
ここで、本実施例においては、フィルタ昇温制御の実行時であって内燃機関1の機関負荷が規定機関負荷以上の場合は、スロットル弁8の開度を制御することによってフィルタ3を目標温度に昇温させる。そして、この場合、燃料添加弁5からの燃料添加が行われていない状態でのフィルタ3の温度とスロットル弁8の開度との関係をECU10によって学習し、この学習した関係に基づいてスロットル弁8の開度が制御される。しかしながら、フィルタ3の温度が低下している最中にフィルタ3の温度とスロットル弁8の開度との関係を学習すると、スロットル弁8の開度に実際に対応したフィルタ3の温度よりも該フィルタ3の温度が高いものとして学習してしまう。そして、このように学習したフィルタ3の温度とスロットル弁8の開度との関係に基づいて、フィルタ3の温度を目標温度とすべくスロットル弁8の開度を制御した場合、実際のフィルタ3の温度は目標温度とずれてしまう。   Here, in this embodiment, when the filter temperature increase control is being executed and the engine load of the internal combustion engine 1 is equal to or greater than the specified engine load, the filter 3 is set to the target temperature by controlling the opening degree of the throttle valve 8. Let the temperature rise. In this case, the ECU 10 learns the relationship between the temperature of the filter 3 and the opening degree of the throttle valve 8 when the fuel addition from the fuel addition valve 5 is not performed, and the throttle valve based on the learned relationship. The opening of 8 is controlled. However, when the relationship between the temperature of the filter 3 and the opening degree of the throttle valve 8 is learned while the temperature of the filter 3 is decreasing, the temperature of the filter 3 actually corresponding to the opening degree of the throttle valve 8 is more affected. Learning is performed assuming that the temperature of the filter 3 is high. When the opening degree of the throttle valve 8 is controlled so that the temperature of the filter 3 becomes the target temperature based on the relationship between the temperature of the filter 3 learned in this way and the opening degree of the throttle valve 8, the actual filter 3 The temperature of will deviate from the target temperature.
そこで、本実施例では、燃料添加弁5からの燃料添加を停止した後、フィルタ3の温度
が定常状態となってから(即ち、図3のaの時期)ECU10によってフィルタ3の温度とスロットル弁8の開度との関係を学習する。そして、このタイミングで学習した両者の関係に基づいて、フィルタ3の温度を目標温度とすべくスロットル弁8の開度を制御する。
Therefore, in this embodiment, after the fuel addition from the fuel addition valve 5 is stopped, the temperature of the filter 3 becomes steady state (that is, at the timing of FIG. 3A) by the ECU 10 and the temperature of the filter 3 and the throttle valve. The relationship with the opening degree of 8 is learned. Based on the relationship between the two learned at this timing, the opening degree of the throttle valve 8 is controlled so that the temperature of the filter 3 becomes the target temperature.
<フィルタ昇温制御実行中に機関負荷が変化した場合の制御ルーチン>
ここで、フィルタ昇温制御実行中に内燃機関1の機関負荷が規定機関負荷より低い状態から規定機関負荷以上に移行した場合の制御ルーチンについて図4に示すフローチャートに基づいて説明する。本ルーチンは、ECU10に予め記憶されており、フィルタ昇温制御の実行中、予め定められた制御実行時間毎に繰り返される。
<Control routine when engine load changes during execution of filter temperature rise control>
Here, a control routine in a case where the engine load of the internal combustion engine 1 shifts from a state lower than the specified engine load to a specified engine load or higher during execution of the filter temperature raising control will be described based on the flowchart shown in FIG. This routine is stored in advance in the ECU 10, and is repeated at predetermined control execution times during the execution of the filter temperature increase control.
本ルーチンでは、先ず、ECU10は、S201において、内燃機関1の機関負荷が規定機関負荷より低い状態から規定機関負荷以上に移行したか否かを判別する。このS201において、肯定判定された場合、ECU10はS202に進み、否定判定された場合、ECU10は本ルーチンの実行を終了する。   In this routine, first, in S201, the ECU 10 determines whether or not the engine load of the internal combustion engine 1 has shifted from a state lower than the specified engine load to a specified engine load or higher. If an affirmative determination is made in S201, the ECU 10 proceeds to S202, and if a negative determination is made, the ECU 10 ends the execution of this routine.
S202に進んだECU10は、燃料添加弁5からの燃料添加を停止する。   The ECU 10 that has proceeded to S202 stops the fuel addition from the fuel addition valve 5.
次に、ECU10は、S203に進み、フィルタ3の温度が定常状態であるか否かを判別する。ここでは、フィルタ3の単位時間当たりの温度変化量が予め定められた規定量以下となったときにフィルタ3の温度が定常状態となったと判断する。このS203において、肯定判定された場合、ECU10はS204に進み、否定判定された場合、ECU10は本ルーチンの実行を終了する。尚、S203において、否定判定された場合、ECU10はS203を繰り返すとしても良い。   Next, the ECU 10 proceeds to S203 and determines whether or not the temperature of the filter 3 is in a steady state. Here, it is determined that the temperature of the filter 3 is in a steady state when the temperature change amount per unit time of the filter 3 is equal to or less than a predetermined amount. If an affirmative determination is made in S203, the ECU 10 proceeds to S204, and if a negative determination is made, the ECU 10 ends the execution of this routine. If a negative determination is made in S203, the ECU 10 may repeat S203.
S204に進んだECU10は、スロットル弁8の開度とフィルタ3の温度との関係を学習する。   In step S204, the ECU 10 learns the relationship between the opening degree of the throttle valve 8 and the temperature of the filter 3.
次に、ECU10は、S205に進み、S204にて学習したスロットル弁8の開度とフィルタ3の温度との関係に基づいて、フィルタ3の温度を目標温度とすべくスロットル弁8の開度制御を実行する。その後、ECU10は本ルーチンの実行を終了する。   Next, the ECU 10 proceeds to S205, and based on the relationship between the opening degree of the throttle valve 8 and the temperature of the filter 3 learned in S204, the opening degree control of the throttle valve 8 so that the temperature of the filter 3 becomes the target temperature. Execute. Thereafter, the ECU 10 ends the execution of this routine.
以上説明した制御ルーチンによれば、フィルタ3の温度が定常状態にあるときにスロットル弁8の開度とフィルタ3の温度との関係を学習し、この学習した関係に基づいてフィルタ3の温度を目標温度とすべくスロットル弁8の開度を制御することで、昇温条件が成立しているときに、内燃機関1の運転状態が低負荷から高負荷に変化した場合であっても、フィルタ3の温度をより正確に目標温度に制御することが出来る。   According to the control routine described above, the relationship between the opening degree of the throttle valve 8 and the temperature of the filter 3 is learned when the temperature of the filter 3 is in a steady state, and the temperature of the filter 3 is determined based on the learned relationship. Even if the operating state of the internal combustion engine 1 changes from a low load to a high load when the temperature raising condition is satisfied by controlling the opening degree of the throttle valve 8 to achieve the target temperature, the filter 3 can be controlled to the target temperature more accurately.
尚、本実施例において、排気通路2に排気絞り弁が設けられている場合は、スロットル弁8の開度制御と併用して排気絞り弁の開度制御を実行しても良い。   In this embodiment, when an exhaust throttle valve is provided in the exhaust passage 2, the opening control of the exhaust throttle valve may be executed in combination with the opening control of the throttle valve 8.
<内燃機関とその吸排気系の概略構成>
図5は、本実施例に係る内燃機関とその吸排気系の概略構成を示す図である。図5に示すように、本実施例に係る内燃機関とその吸排気系の概略構成は、上述した実施例1に係る内燃機関とその吸排気系の概略構成から燃料添加弁5を除いた点のみが異なりその他の構成は同様である。
<Schematic configuration of internal combustion engine and its intake / exhaust system>
FIG. 5 is a diagram showing a schematic configuration of the internal combustion engine and its intake / exhaust system according to the present embodiment. As shown in FIG. 5, the schematic configuration of the internal combustion engine and its intake / exhaust system according to this embodiment is obtained by removing the fuel addition valve 5 from the schematic configuration of the internal combustion engine according to the first embodiment and its intake / exhaust system. The only difference is the rest of the configuration.
<フィルタ昇温制御>
本実施例においては、フィルタ3(フィルタ3に担持された酸化触媒)に燃料を供給す
ることで該フィルタ3を昇温させる場合、内燃機関1の気筒内において主燃料噴射よりも後の時期であって膨張行程または排気行程で副燃料噴射を実行することで、フィルタ3より上流側から該フィルタ3に燃料を供給する。
<Filter temperature rise control>
In the present embodiment, when the temperature of the filter 3 is raised by supplying fuel to the filter 3 (the oxidation catalyst carried on the filter 3), the timing is later than the main fuel injection in the cylinder of the internal combustion engine 1. Thus, fuel is supplied to the filter 3 from the upstream side of the filter 3 by executing the auxiliary fuel injection in the expansion stroke or the exhaust stroke.
ここで、副燃料噴射によってフィルタ3に燃料を供給する場合、内燃機関1の機関回転数が高くなるほど1回の燃焼サイクルにかかる時間が短くなるため、1回の燃焼サイクル毎に実行可能な副燃料噴射の回数が少なくなる。そのため、高回転運転領域では、副燃料噴射によっては、フィルタ3を目標温度に昇温させるのに十分な量の燃料を供給することが困難な場合がある。   Here, when fuel is supplied to the filter 3 by auxiliary fuel injection, the time required for one combustion cycle becomes shorter as the engine speed of the internal combustion engine 1 becomes higher. The number of fuel injections is reduced. Therefore, in the high rotation operation region, depending on the auxiliary fuel injection, it may be difficult to supply a sufficient amount of fuel to raise the temperature of the filter 3 to the target temperature.
そこで、本実施例では、図6に示すように、フィルタ昇温制御を実行するときに、内燃機関1の運転状態が(A)の領域にあるとき、即ち、内燃機関1の機関負荷が規定機関負荷より低く且つ内燃機関1の機関回転数が規定機関回転数より低い場合は、副燃料噴射を実行しその噴射量を制御することでフィルタ3を目標温度に昇温させる。そして、フィルタ昇温制御を実行するときに、内燃機関1の運転状態が(B)の領域にあるとき、即ち、内燃機関1の機関負荷が規定機関負荷以上の場合または内燃機関1の機関回転数が規定機関回転数以上の場合は、副燃料噴射を禁止すると共に、スロットル弁8の開度を制御することでフィルタ3を目標温度に昇温させる。   Therefore, in this embodiment, as shown in FIG. 6, when the filter temperature increase control is executed, when the operating state of the internal combustion engine 1 is in the region (A), that is, the engine load of the internal combustion engine 1 is specified. When the engine load is lower than the engine load and the engine speed of the internal combustion engine 1 is lower than the specified engine speed, the auxiliary fuel injection is executed and the injection amount is controlled to raise the temperature of the filter 3 to the target temperature. Then, when executing the filter temperature raising control, when the operating state of the internal combustion engine 1 is in the region (B), that is, when the engine load of the internal combustion engine 1 is equal to or higher than the specified engine load, or the engine rotation of the internal combustion engine 1 When the number is equal to or higher than the specified engine speed, the auxiliary fuel injection is prohibited and the filter 3 is heated to the target temperature by controlling the opening degree of the throttle valve 8.
図6は、内燃機関1の運転状態とフィルタ3の昇温方法との関係を示す図である。 図6において、縦軸は機関負荷を表し、横軸は機関回転数を表している。また、破線は、領域(A)と領域(B)との境界を表し、実線は機関回転数に応じた最大機関負荷を表している。   FIG. 6 is a diagram showing the relationship between the operating state of the internal combustion engine 1 and the temperature raising method of the filter 3. In FIG. 6, the vertical axis represents the engine load, and the horizontal axis represents the engine speed. The broken line represents the boundary between the region (A) and the region (B), and the solid line represents the maximum engine load corresponding to the engine speed.
ここで、領域(A)と領域(B)との境界は規定機関負荷と規定回転数とで定められている。規定機関負荷は、上述した実施例1に係る規定機関負荷と同様であり、機関回転数が高いほど低い値となっている。また、規定機関回転数とは、予め定められた機関回転数であって、フィルタ3を目標温度に昇温させるのに十分な量の燃料を供給するのが可能となる副燃料噴射の回数を確保するのが困難となる機関回転数の閾値である。   Here, the boundary between the region (A) and the region (B) is determined by the specified engine load and the specified speed. The specified engine load is the same as the specified engine load according to the first embodiment described above, and becomes a lower value as the engine speed is higher. The specified engine speed is a predetermined engine speed, and is the number of sub fuel injections that can supply a sufficient amount of fuel to raise the temperature of the filter 3 to the target temperature. This is the threshold value of the engine speed that is difficult to secure.
次に、本実施例に係るフィルタ昇温制御ルーチンについて図7に示すフローチャート図に基づいて説明する。尚、本ルーチンは、図2に示すフィルタ昇温制御ルーチンにおけるS104をS304とし、さらにS303を加えたものである。そのため、ここではS303およびS304についてのみ説明し、その他のステップの説明を省略する。本ルーチンも、前記と同様、ECU10に予め記憶されており、内燃機関1の運転中、予め定められた制御実行時間毎に繰り返される。   Next, the filter temperature increase control routine according to this embodiment will be described with reference to the flowchart shown in FIG. In this routine, step S104 in the filter temperature raising control routine shown in FIG. 2 is changed to step S304, and step S303 is further added. Therefore, only S303 and S304 will be described here, and description of other steps will be omitted. This routine is also stored in advance in the ECU 10 as described above, and is repeated at predetermined control execution times during the operation of the internal combustion engine 1.
本ルーチンにおいては、S102において、否定判定された場合、ECU10はS303に進む。   In this routine, if a negative determination is made in S102, the ECU 10 proceeds to S303.
S303において、ECU10は、内燃機関1の機関回転数が規定機関回転数以上であるか否か判別する。このS303において、肯定判定された場合、ECU10はS103に進み、否定判定された場合、ECU10はS304に進む。   In S303, the ECU 10 determines whether or not the engine speed of the internal combustion engine 1 is equal to or higher than a specified engine speed. If an affirmative determination is made in S303, the ECU 10 proceeds to S103, and if a negative determination is made, the ECU 10 proceeds to S304.
S304に進んだECU10は、内燃機関1の気筒内での副燃料噴射を実行し、この副燃料噴射による噴射量を制御することで、現時点でのフィルタ3の温度が目標温度より低い場合は該フィルタ3を目標温度にまで昇温させ、現時点でのフィルタ3の温度が目標温度である場合はこの目標温度を維持する。尚、S304において、副燃料噴射が実行される場合、スロットル弁8の開度は内燃機関1の機関負荷から定められる開度に制御される。   The ECU 10 that has proceeded to S304 executes the auxiliary fuel injection in the cylinder of the internal combustion engine 1, and controls the injection amount by the auxiliary fuel injection, so that if the current temperature of the filter 3 is lower than the target temperature, the ECU 10 The temperature of the filter 3 is raised to the target temperature, and this target temperature is maintained when the current temperature of the filter 3 is the target temperature. In S304, when the auxiliary fuel injection is executed, the opening of the throttle valve 8 is controlled to an opening determined from the engine load of the internal combustion engine 1.
以上説明した制御ルーチンによれば、フィルタ3への燃料供給が副燃料噴射によって行われる場合において、内燃機関の機関回転数が高い場合であっても、より確実にフィルタ3を目標温度に昇温することが出来る。即ち、より広範囲の運転状態でフィルタ3を目標温度に昇温させることが可能となるため、堆積したPMの酸化・除去をより広範囲の運転状態で実行することが出来る。   According to the control routine described above, when the fuel supply to the filter 3 is performed by sub fuel injection, the filter 3 is more reliably heated to the target temperature even when the engine speed of the internal combustion engine is high. I can do it. That is, the filter 3 can be raised to the target temperature in a wider range of operating conditions, so that the deposited PM can be oxidized and removed in a wider range of operating conditions.
尚、本実施例において、フィルタ昇温制御実行中に、内燃機関1の運転状態が、図6に示す領域(A)から領域(B)に移行した場合、移行した時点で副燃料噴射は停止される。そして、副燃料噴射を停止した後、フィルタ3の温度が定常状態となってからECU10によってフィルタ3の温度とスロットル弁8の開度との関係を学習し、このタイミングで学習した両者の関係に基づいて、フィルタ3の温度を目標温度とすべくスロットル弁8の開度を制御する。   In this embodiment, when the operation state of the internal combustion engine 1 shifts from the region (A) to the region (B) shown in FIG. 6 during execution of the filter temperature raising control, the auxiliary fuel injection is stopped at the time of the shift. Is done. After the sub fuel injection is stopped, the ECU 10 learns the relationship between the temperature of the filter 3 and the opening of the throttle valve 8 after the temperature of the filter 3 reaches a steady state. Based on this, the opening degree of the throttle valve 8 is controlled so that the temperature of the filter 3 becomes the target temperature.
このような制御を行うことによって、フィルタ昇温制御の実行中に、内燃機関1の運転状態が変化した場合であっても、フィルタ3の温度をより正確に目標温度に制御することが出来る。   By performing such control, the temperature of the filter 3 can be more accurately controlled to the target temperature even when the operating state of the internal combustion engine 1 changes during the execution of the filter temperature raising control.
また、本実施例に係る上記制御ルーチンも、実施例1に係るフィルタ昇温制御ルーチンと同様、フィルタ3にNOx触媒を担持した場合、もしくは、フィルタ3の代わりにNOx触媒を配置した場合において、NOx触媒に吸蔵されたSOxを還元する場合にも適用することが出来る。   In addition, the control routine according to the present embodiment is similar to the filter temperature increase control routine according to the first embodiment. When the NOx catalyst is supported on the filter 3 or when the NOx catalyst is disposed instead of the filter 3, The present invention can also be applied to reducing SOx stored in the NOx catalyst.
本発明の実施例1に係る内燃機関およびその吸排気系の概略構成を示す図。BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows schematic structure of the internal combustion engine which concerns on Example 1 of this invention, and its intake / exhaust system. 本発明の実施例1に係るフィルタ昇温制御ルーチンを示すフローチャート図。The flowchart figure which shows the filter temperature rising control routine which concerns on Example 1 of this invention. フィルタ昇温制御実行中における、機関負荷および燃料添加弁からの燃料添加、フィルタの温度、スロットル弁の開度の関係を示すタイムチャート。The time chart which shows the relationship between engine load, the fuel addition from a fuel addition valve, the temperature of a filter, and the opening degree of a throttle valve during filter temperature increase control execution. フィルタ昇温制御実行中に内燃機関の機関負荷が規定機関負荷より低い状態から規定機関負荷以上に移行した場合の制御ルーチンを示すフローチャート図。The flowchart figure which shows the control routine when the engine load of an internal combustion engine transfers more than a regulation engine load from the state lower than a regulation engine load during filter temperature increase control execution. 本発明の実施例2に係る内燃機関およびその吸排気系の概略構成を示す図。The figure which shows schematic structure of the internal combustion engine which concerns on Example 2 of this invention, and its intake-exhaust system. 本発明の実施例2に係る、内燃機関の運転状態とフィルタの昇温方法との関係を示す図。The figure which shows the relationship between the driving | running state of an internal combustion engine and the temperature rising method of a filter based on Example 2 of this invention. 本発明の実施例2に係るフィルタ昇温制御ルーチンを示すフローチャート図。The flowchart figure which shows the filter temperature rising control routine which concerns on Example 2 of this invention.
符号の説明Explanation of symbols
1・・・内燃機関
2・・・排気通路
3・・・パティキュレートフィルタ
5・・・燃料添加弁
7・・・排気温度センサ
8・・・スロットル弁
10・・ECU
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Exhaust passage 3 ... Particulate filter 5 ... Fuel addition valve 7 ... Exhaust temperature sensor 8 ... Throttle valve 10 ... ECU

Claims (3)

  1. 内燃機関の排気通路に設けられた酸化機能を有する排気浄化手段と、
    該排気浄化手段より上流側から該排気浄化手段に燃料成分を供給する燃料成分供給手段と、
    前記内燃機関の吸入空気量を制御する吸入空気量制御手段と、
    前記燃料成分供給手段からの燃料成分の供給が実行されていない状態における、前記内燃機関の吸入空気量と前記排気浄化手段の温度との関係を学習する学習手段と、を備え、
    前記排気浄化手段の排気浄化能力を再生すべく前記排気浄化手段を目標温度に昇温させる昇温条件が成立しているときに、前記内燃機関の機関負荷が規定機関負荷より低い場合は、前記燃料成分供給手段から前記排気浄化手段に供給される燃料成分量を制御することで前記排気浄化手段の温度を前記目標温度に上昇または維持させると共に、前記吸入空気量制御手段によって前記内燃機関の吸入空気量を該内燃機関の機関回転数および該内燃機関の機関負荷から定められる吸入空気量に制御し、
    前記昇温条件が成立しているときに、前記内燃機関の機関負荷が前記規定機関負荷以上の場合は、前記燃料成分供給手段からの燃料成分の供給を禁止すると共に、前記吸入空気量制御手段によって前記内燃機関の吸入空気量を制御することで前記排気浄化手段の温度を前記目標温度に上昇または維持させ
    前記昇温条件が成立しているときに、前記内燃機関の運転状態が、前記燃料成分供給手段から前記排気浄化手段に供給される燃料成分量を制御することで前記排気浄化手段を前記目標温度に昇温させる運転領域から、前記吸入空気量制御手段によって前記内燃機関の吸入空気量を制御することで前記排気浄化手段を前記目標温度に昇温させる運転領域に移行した場合、前記燃料成分供給手段からの燃料成分の供給を停止した後、前記排気浄化手段の温度が定常状態となってから、前記学習手段によって、前記内燃機関の吸入空気量と前記排気浄化手段の温度との関係の学習を実行し、
    前記学習手段によって学習された前記内燃機関の吸入空気量と前記排気浄化手段の温度との関係に基づいて、前記排気浄化手段の温度を前記目標温度とすべく前記吸入空気量制御手段によって前記内燃機関の吸入空気量を制御することを特徴とする内燃機関の排気浄化装置。
    Exhaust purification means having an oxidation function provided in the exhaust passage of the internal combustion engine;
    Fuel component supply means for supplying a fuel component to the exhaust purification means from the upstream side of the exhaust purification means;
    Intake air amount control means for controlling the intake air amount of the internal combustion engine;
    Learning means for learning the relationship between the intake air amount of the internal combustion engine and the temperature of the exhaust purification means in a state where the supply of the fuel component from the fuel component supply means is not executed ,
    When the engine load of the internal combustion engine is lower than a specified engine load when a temperature raising condition for raising the temperature of the exhaust purification unit to a target temperature is established to regenerate the exhaust purification capability of the exhaust purification unit, By controlling the amount of fuel component supplied from the fuel component supply means to the exhaust purification means, the temperature of the exhaust purification means is raised or maintained at the target temperature, and the intake air amount control means is used to intake the internal combustion engine. Controlling the amount of air to an intake air amount determined from the engine speed of the internal combustion engine and the engine load of the internal combustion engine;
    When the temperature increase condition is satisfied and the engine load of the internal combustion engine is equal to or greater than the specified engine load, the supply of the fuel component from the fuel component supply means is prohibited and the intake air amount control means To control the intake air amount of the internal combustion engine to raise or maintain the temperature of the exhaust purification means at the target temperature ,
    When the temperature raising condition is satisfied, the operating state of the internal combustion engine controls the amount of fuel component supplied from the fuel component supply unit to the exhaust purification unit, thereby controlling the exhaust purification unit to the target temperature. The fuel component is supplied when the operation region is increased from the operation region to the target temperature by controlling the intake air amount of the internal combustion engine by the intake air amount control unit. After the supply of the fuel component from the means is stopped, the learning means learns the relationship between the intake air amount of the internal combustion engine and the temperature of the exhaust purification means after the temperature of the exhaust purification means reaches a steady state. Run
    Based on the relationship between the intake air amount of the internal combustion engine learned by the learning means and the temperature of the exhaust purification means, the internal combustion engine controls the internal combustion engine by the intake air amount control means so that the temperature of the exhaust purification means becomes the target temperature. An exhaust emission control device for an internal combustion engine, wherein the intake air amount of the engine is controlled .
  2. 前記燃料成分供給手段が、前記内燃機関の気筒内において主燃料噴射よりも後の時期であって膨張行程または排気行程で副燃料噴射を実行することで、前記排気浄化手段より上流側から該排気浄化手段に燃料成分を供給する場合において、
    前記昇温条件が成立しているときに前記内燃機関の機関負荷が規定機関負荷より低い場合であっても、前記内燃機関の機関回転数が規定機関回転数以上の場合は、前記燃料成分供給手段からの燃料成分の供給を禁止すると共に、前記吸入空気量制御手段によって前記内燃機関の吸入空気量を制御することで前記排気浄化手段の温度を前記目標温度に上昇または維持させることを特徴とする請求項1記載の内燃機関の排気浄化装置。
    The fuel component supply means performs sub fuel injection in the expansion stroke or exhaust stroke at a time later than the main fuel injection in the cylinder of the internal combustion engine, so that the exhaust from the upstream side of the exhaust purification means. When supplying fuel components to the purification means,
    Even when the engine load of the internal combustion engine is lower than the specified engine load when the temperature raising condition is satisfied, the fuel component supply is performed when the engine speed of the internal combustion engine is equal to or higher than the specified engine speed. And prohibiting the supply of the fuel component from the means, and controlling the intake air amount of the internal combustion engine by the intake air amount control means to raise or maintain the temperature of the exhaust purification means to the target temperature. The exhaust emission control device for an internal combustion engine according to claim 1.
  3. 前記規定機関負荷を、前記昇温条件が成立しているときの前記内燃機関の機関回転数が高いほど低い値に設定することを特徴とする請求項1または2記載の内燃機関の排気浄化装置。   The exhaust gas purification apparatus for an internal combustion engine according to claim 1 or 2, wherein the prescribed engine load is set to a lower value as the engine speed of the internal combustion engine is higher when the temperature increase condition is satisfied. .
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