JPH06317142A - Exhaust emission control device of internal combustion engine - Google Patents
Exhaust emission control device of internal combustion engineInfo
- Publication number
- JPH06317142A JPH06317142A JP5104347A JP10434793A JPH06317142A JP H06317142 A JPH06317142 A JP H06317142A JP 5104347 A JP5104347 A JP 5104347A JP 10434793 A JP10434793 A JP 10434793A JP H06317142 A JPH06317142 A JP H06317142A
- Authority
- JP
- Japan
- Prior art keywords
- absorbent
- exhaust
- intake
- engine
- exhaust gas
- 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
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
- F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
- F01N3/0885—Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
- F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
- F01N3/0842—Nitrogen oxides
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
- F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
- F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2260/00—Exhaust treating devices having provisions not otherwise provided for
- F01N2260/14—Exhaust treating devices having provisions not otherwise provided for for modifying or adapting flow area or back-pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
- F02D9/04—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning exhaust conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
- F02M26/17—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system
- F02M26/21—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system with EGR valves located at or near the connection to the intake system
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Exhaust-Gas Circulating Devices (AREA)
- Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、内燃機関の排気浄化装
置に関し、詳細にはディーゼルエンジンや希薄空燃比の
燃焼を行うガソリンエンジン等リーン空燃比の燃焼を行
う内燃機関の排気中のＮＯX 成分を効果的に除去可能な
排気浄化装置に関する。The present invention relates to relates to an exhaust purifying apparatus for an internal combustion engine, in the exhaust gas of an internal combustion engine causing combustion of gasoline engines such as lean air causing combustion of a diesel engine or a lean air-fuel ratio in particular NO X The present invention relates to an exhaust gas purification device that can effectively remove components.
【０００２】[0002]
【従来の技術】リーン空燃比の燃焼を行う内燃機関の排
気中のＮＯX を浄化する排気浄化装置の例としては、特
開昭６２−１０６８２６号公報に記載されたものがあ
る。同公報の装置では、ディーゼルエンジンの排気通路
に、酸素存在下でＮＯX を吸収するＮＯX 吸収剤を配置
し、吸収剤のＮＯX 吸収効率が低下した時点でＮＯ X 吸
収剤への排気流入を遮断してＮＯX 吸収剤に還元剤を導
入することにより吸収したＮＯX を放出させ、還元浄化
している。2. Description of the Related Art Exhaust gas from an internal combustion engine that burns lean air-fuel ratio
NO in the airXAs an example of an exhaust purification device that purifies
The one described in Japanese Laid-Open Patent Publication No. 62-106826 is available.
It In the device of the publication, the exhaust passage of the diesel engine
NO in the presence of oxygenXAbsorbing NOXPlace absorbent
Absorbent NOXNO when the absorption efficiency decreases XSucking
NO by shutting off the exhaust gas inflow to the sorbentXGuide the reducing agent to the absorbent
NO absorbed by enteringXRelease and reduce purification
is doing.
【０００３】上記公報の装置は、酸素を多量に含む排気
がＮＯX 吸収剤に流入することを防止しながらＮＯX 吸
収剤に還元剤を導入することによりＮＯX 吸収剤の雰囲
気酸素濃度を低下させてＮＯX 吸収剤からＮＯX を放出
させ、還元剤によりこのＮＯ X を還元浄化している。し
かし、上記公報の装置では、ＮＯX 吸収剤からのＮＯX
放出及び還元浄化（以下ＮＯX 吸収剤の「再生」とい
う）を行う際にＮＯX 吸収剤への排気流入を遮断する必
要があるため、機関運転中にＮＯX の放出、浄化を行お
うとすると、排気系に複数のＮＯX 吸収剤を並列配置し
て順次切換えて排気流入を遮断してＮＯ X 吸収剤の再生
を行うようにして排気流路を確保する必要があり、装置
の複雑化や車両への搭載性の悪化を生じるおそれがあ
る。The device disclosed in the above publication is exhaust gas containing a large amount of oxygen.
Is NOXNO while preventing it from flowing into the absorbentXSucking
NO by introducing a reducing agent into the collecting agentXAbsorbent atmosphere
NO by reducing oxygen concentrationXAbsorbent to NOXEmit
And reduce this NO by reducing agent XIs reduced and purified. Shi
However, in the device of the above publication, NOXNO from absorbentX
Release and reduction purification (hereinafter NOX"Regeneration" of absorbent
No when performingXIt is necessary to block the exhaust gas flow into the absorbent.
Because it is necessary, NO during engine operationXRelease and purify
If you try, multiple NOXAbsorbents are arranged in parallel
And sequentially switch to block exhaust gas inflow and NO XRegeneration of absorbent
It is necessary to secure the exhaust flow path by performing
May be complicated and the mountability on the vehicle may deteriorate.
It
【０００４】一方、本願出願人は、ＮＯX 吸収剤の再生
時にある程度の量の排気を流したまま還元剤を導入して
ＮＯX 吸収剤の再生を行い、ＮＯX 吸収剤再生時にも排
気流入を遮断しない排気浄化装置を既に提案している
（特願平４−２６３８９２号）。この装置によれば、Ｎ
ＯX 吸収剤再生時にも排気流路が確保され、単一のＮＯ
X 吸収剤を用いて機関運転中にＮＯX 吸収剤の再生を行
うことができるため、複数のＮＯX 吸収剤を設ける必要
がないので装置の簡易化と搭載性の向上とを図ることが
できる。On the other hand, the applicant of the present applicationXRegeneration of absorbent
Sometimes introducing a reducing agent with a certain amount of exhaust flowing
NOXRegenerate the absorbent, NOXExhausted even when absorbent is regenerated
We have already proposed an exhaust purification system that does not block air inflow
(Japanese Patent Application No. 4-263892). According to this device, N
OXThe exhaust flow path is secured even when the absorbent is regenerated, and a single NO
XNO during engine operation using absorbentXRegenerate the absorbent
Multiple NOXNeed to provide absorbent
Since it does not have any, it is possible to simplify the device and improve mountability.
it can.
【０００５】上記特願平４−２６３８９２号に提案した
装置では、ＮＯX 吸収剤上流側の排気系に排気中の酸素
を消費する酸素消費手段を設けＮＯX 吸収剤に流入する
排気中の酸素濃度を低減し、ＮＯX 吸収剤再生時のＮＯ
X の放出を容易にしている。In the device proposed in Japanese Patent Application No. 4-263892, the exhaust system upstream of the NO x absorbent is provided with oxygen consuming means for consuming oxygen in the exhaust gas, and the oxygen in the exhaust gas flowing into the NO x absorbent is provided. Decrease the concentration and NO when regenerating NO X absorbent
It facilitates the release of X.
【０００６】[0006]
【発明が解決しようとする課題】上記特願平４−２６３
８９２号の装置のようにＮＯX 吸収剤に排気を流したま
ま再生を行う場合、流入する排気中に含まれる酸素を消
費してＮＯX 吸収剤の雰囲気酸素濃度を低下させる必要
が生じる。上記特願平４−２６３８９２号の装置では、
機関吸気通路に吸気絞り弁を設け、エンジンブレーキ時
に吸気絞り弁を閉弁して機関吸入空気量を絞るとともに
ＮＯX 吸収剤上流側に設けた酸素消費手段に還元剤を供
給して燃焼させて排気中の酸素を消費し、ＮＯX 吸収剤
に流入する排気中の酸素濃度を低下させてＮＯX 吸収剤
の再生を行っている。[Patent Document 1] Japanese Patent Application No. 4-263
When the regeneration is performed while the exhaust gas is flowing through the NO x absorbent as in the apparatus of No. 892, it is necessary to consume oxygen contained in the inflowing exhaust gas to reduce the atmospheric oxygen concentration of the NO x absorbent. In the apparatus of Japanese Patent Application No. 4-263892 mentioned above,
An intake throttle valve is provided in the engine intake passage, and the intake throttle valve is closed during engine braking to throttle the engine intake air amount, and the reducing agent is supplied to the oxygen consuming means provided upstream of the NO x absorbent to burn it. Oxygen in the exhaust gas is consumed, and the oxygen concentration in the exhaust gas flowing into the NO x absorbent is reduced to regenerate the NO x absorbent.
【０００７】ディーゼルエンジンなどリーン空燃比の燃
焼を行う機関では排気中に多量の酸素が含まれるため、
ＮＯX 吸収剤に排気を流したまま再生を行う場合、排気
中の酸素を消費するために必要となる還元剤の量は非常
に多くなり還元剤消費量が増大する問題が生じる。上記
特願平４−２６３８９２号ではＮＯX 吸収剤再生時に機
関吸入空気量を絞ることにより機関に流入する酸素量を
低減して、排気中の酸素消費に要する還元剤の量の減少
を図っている。In an engine that burns at a lean air-fuel ratio such as a diesel engine, a large amount of oxygen is contained in the exhaust gas.
When the regeneration is performed with the exhaust flowing through the NO x absorbent, the amount of the reducing agent required to consume the oxygen in the exhaust becomes very large, which causes a problem that the reducing agent consumption increases. In the above-mentioned Japanese Patent Application No. 4-263892, the amount of oxygen flowing into the engine is reduced by reducing the amount of engine intake air during regeneration of the NO x absorbent, and the amount of reducing agent required for consuming oxygen in the exhaust gas is reduced. There is.
【０００８】ＮＯX 吸収剤に排気を流したまま再生を行
う場合には、機関吸入空気量を減少させるほど排気中の
酸素消費に要する還元剤の量が減少する。しかし、上記
特願平４−２６３８９２号の装置のように、吸気絞り弁
を用いて機関吸入空気量を低減しようとした場合、機関
吸入空気量を大幅に低減する事ができず、還元剤消費量
の十分な低減を図ることができない問題が生じる。When the regeneration is performed while the exhaust gas is flowing through the NO x absorbent, the amount of the reducing agent required for consuming oxygen in the exhaust gas decreases as the engine intake air amount decreases. However, when the intake air throttle amount is used to reduce the engine intake air amount as in the device of the above-mentioned Japanese Patent Application No. 4-263892, the engine intake air amount cannot be significantly reduced and the reducing agent consumption is reduced. There arises a problem that the amount cannot be sufficiently reduced.
【０００９】すなわち、上記特願平４−２６３８９２号
の装置ではエンジンブレーキの際に吸気シャッターバル
ブの絞り量を大きくとり過ぎると、吸気マニホルドの負
圧が過度に増大し吸入行程のシリンダ内負圧が大きくな
る。このため、エンジンブレーキ時に運転者の予期した
以上の減速トルクが発生し、減速ショックが大きくなっ
て運転感覚が悪化するのみならず、シリンダ負圧の増大
によりピストンリングとシリンダ壁との間から潤滑油が
燃焼室内に入り込みエンジンの潤滑油消費量が増大する
問題が生じてしまう。このため、吸気シャッターバルブ
による機関吸入空気量の絞り量をある程度以上大きくと
ることはできず還元剤の消費量を十分に低減することが
困難になっている。That is, in the device of Japanese Patent Application No. 4-263892 mentioned above, when the throttle amount of the intake shutter valve is excessively increased during engine braking, the negative pressure of the intake manifold excessively increases and the negative pressure in the cylinder during the intake stroke. Grows larger. For this reason, deceleration torque more than expected by the driver is generated during engine braking, not only does the deceleration shock increase and the driving sensation worsens, but the increase in cylinder negative pressure causes lubrication between the piston ring and cylinder wall. There is a problem that the oil enters the combustion chamber and the consumption of lubricating oil of the engine increases. Therefore, the throttle amount of the engine intake air amount by the intake shutter valve cannot be increased to a certain extent or more, and it is difficult to sufficiently reduce the reducing agent consumption amount.
【００１０】本発明は、上述の問題に鑑み、運転間隔の
悪化や機関潤滑油消費量の増大を生じることなくＮＯX
吸収剤再生時の還元剤消費量を低減することができる排
気浄化装置を提供することを目的としている。In view of the above-mentioned problems, the present invention provides NO X without causing a deterioration in operating intervals and an increase in engine lubricating oil consumption.
It is an object of the present invention to provide an exhaust emission control device that can reduce the amount of reducing agent consumed during regeneration of the absorbent.
【００１１】[0011]
【課題を解決するための手段】本発明によれば、リーン
空燃比の燃焼を行う内燃機関の排気通路に、流入排気の
空燃比がリーンのときにＮＯX を吸収し流入排気の酸素
濃度が低下したときに吸収したＮＯX を放出するＮＯX
吸収剤を配置して排気中のＮＯX を吸収させ、前記ＮＯ
X 吸収剤に還元剤を供給することにより排気中の酸素濃
度を低下させ、ＮＯX 吸収剤から吸収したＮＯX を放出
させるとともに該ＮＯX を還元浄化する内燃機関の排気
浄化装置において、前記ＮＯX 吸収剤に還元剤を供給す
る際に、機関排気の少なくとも一部を機関吸気通路に還
流させる手段を備えたことを特徴とする内燃機関の排気
浄化装置が提供される。According to the present invention, in order to solve the problems], in an exhaust passage of an internal combustion engine causing combustion of lean air-fuel ratio, the air-fuel ratio of the inflowing exhaust gas is the oxygen concentration of the inflowing exhaust absorbs NO X when the lean NO X to release the absorbed NO X when lowered
An absorbent is arranged to absorb NO x in the exhaust gas,
Lowering the oxygen concentration in the exhaust gas by supplying a reducing agent to X absorbent, the exhaust purification system of an internal combustion engine to reduce and purify the NO X with the release of NO X absorbed from the NO X absorbent, the NO There is provided an exhaust gas purification device for an internal combustion engine, which is provided with means for returning at least a part of engine exhaust gas to an engine intake passage when supplying a reducing agent to the X absorbent.
【００１２】[0012]
【作用】ＮＯX 吸収剤再生時に機関排気を吸気側に還流
させることにより、吸気マニホルドの負圧を増大させる
ことなく外部から機関に吸入される新気の量が低減され
る。このため、新気の量を大幅に低減した場合でも潤滑
油の消費量増大や運転感覚の悪化を伴うことなく還元剤
消費量が大幅に低減される。By recirculating the engine exhaust gas to the intake side when the NO x absorbent is regenerated, the amount of fresh air drawn into the engine from the outside is reduced without increasing the negative pressure of the intake manifold. Therefore, even if the amount of fresh air is significantly reduced, the amount of reducing agent consumed is significantly reduced without increasing the amount of lubricating oil consumed or deteriorating the driving feeling.
【００１３】[0013]
【実施例】以下、添付図面を参照して本発明の実施例に
ついて説明する。図１は本発明の内燃機関の排気浄化装
置の一実施例の構成を示す図である。図１において、１
はディーゼルエンジン、２はエンジンの吸気管、３はエ
ンジンの排気管を示す。エンジンの吸気管２には吸気シ
ャッターバルブ６が設けられている。また、排気管３に
はＮＯX 吸収剤１５を収容したケーシングが接続されて
おり、ＮＯX 吸収剤１５の下流側の排気管３には、排気
シャッターバルブ８が設けられており、さらに本実施例
では、排気管３のＮＯX 吸収剤１５上流側部分と吸気管
２の吸気シャッターバルブ６下流部分とを接続する排気
再循環のためのＥＧＲ通路１１が設けられている。図１
に１２で示すのはＥＧＲ通路１１上に設けられたＥＧＲ
弁である。ＥＧＲ弁１２の弁体１２ａには負圧アクチュ
エータ１３が接続され、ＥＧＲ弁１２の作動を制御して
いる。負圧アクチュエータ１３はダイヤフラム１３ａに
より形成される負圧室１３ｂとダイヤフラム１３ａを押
圧付勢するばね１３ｃとを備えており、ＥＧＲ弁１２の
弁体１２ａはダイヤフラム１３ａに連結されている。ば
ね１３ｃは常時弁体１２が弁座に密着する方向にダイヤ
フラム１３ａを押圧しており、通常時はＥＧＲ通路１１
は弁体１２により閉塞され、ＥＧＲ通路１１から吸気通
路２には排気は還流しないが、通常運転中に負圧アクチ
ュエータ１３の負圧室１３ｂに適宜な負圧源から運転状
態に応じて負圧を供給することによりＥＧＲ弁１２を開
弁させ排気再循環を行うことができる。さらに、本実施
例ではばね１３ｃの付勢力は、吸気管２内の圧力が低下
してＥＧＲ通路１１内の排気圧力と吸気圧力との差が所
定値以上になったときに排気がばね１３ｃの付勢力に抗
して弁体１２ａを押し上げて吸気管２内に流入するよう
に適宜に設定されている。Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing the configuration of an embodiment of an exhaust gas purification apparatus for an internal combustion engine of the present invention. In FIG. 1, 1
Is a diesel engine, 2 is an engine intake pipe, and 3 is an engine exhaust pipe. An intake shutter valve 6 is provided in the intake pipe 2 of the engine. Further, a casing accommodating the NO x absorbent 15 is connected to the exhaust pipe 3, and an exhaust shutter valve 8 is provided in the exhaust pipe 3 on the downstream side of the NO x absorbent 15. examples, an EGR passage 11 for exhaust gas recirculation for connecting the NO X absorbent 15 upstream portion of the exhaust pipe 3 and the intake shutter valve 6 downstream portion of the intake pipe 2 is provided. Figure 1
Reference numeral 12 indicates an EGR provided on the EGR passage 11.
It is a valve. A negative pressure actuator 13 is connected to the valve body 12a of the EGR valve 12 to control the operation of the EGR valve 12. The negative pressure actuator 13 includes a negative pressure chamber 13b formed by a diaphragm 13a and a spring 13c for biasing the diaphragm 13a, and the valve body 12a of the EGR valve 12 is connected to the diaphragm 13a. The spring 13c constantly presses the diaphragm 13a in a direction in which the valve body 12 is in close contact with the valve seat.
Is closed by the valve body 12, and the exhaust gas does not flow back from the EGR passage 11 to the intake passage 2. However, during normal operation, the negative pressure chamber 13b of the negative pressure actuator 13 receives a negative pressure from an appropriate negative pressure source according to the operating state. Is supplied, the EGR valve 12 can be opened and exhaust gas recirculation can be performed. Further, in the present embodiment, the urging force of the spring 13c is such that when the pressure in the intake pipe 2 decreases and the difference between the exhaust pressure in the EGR passage 11 and the intake pressure exceeds a predetermined value, It is appropriately set so as to push up the valve body 12a against the biasing force and flow into the intake pipe 2.
【００１４】吸気シャッターバルブ６と排気シャッター
バルブ８は全開時に抵抗の少ないバタフライ弁等の形式
の弁とされ、エンジンの通常運転時には全開に維持され
吸気抵抗や排気抵抗を生じない。また、吸気シャッター
バルブ６は負圧アクチュエータ、ステッパモータ等の適
宜な形式のアクチュエータ７を備え、後述のＮＯX 吸収
剤１５再生操作時に所定開度まで閉弁され吸気管２を絞
りＮＯX 吸収剤１５を通過する排気流量を低減する。排
気シャッターバルブ８は、同様に適宜な形式のアクチュ
エータ９を備え、ＮＯX 吸収剤１５再生操作時に所定開
度まで閉弁され排気管３を絞り排気圧力を上昇させてＥ
ＧＲ通路１１を通って吸気管２に還流する排気の流量を
増大させる。The intake shutter valve 6 and the exhaust shutter valve 8 are valves of a type such as a butterfly valve having a low resistance when fully opened, and are kept fully open during normal operation of the engine so that intake resistance and exhaust resistance are not generated. Further, the intake shutter valve 6 is provided with an actuator 7 of an appropriate type such as a negative pressure actuator, a stepper motor, etc., and is closed to a predetermined opening during a NO x absorbent 15 regeneration operation described later to throttle the intake pipe 2 to reduce the NO x absorbent. The exhaust flow rate passing through 15 is reduced. Similarly, the exhaust shutter valve 8 is provided with an actuator 9 of an appropriate type, and is closed to a predetermined opening when the NO x absorbent 15 is regenerated, and the exhaust pipe 3 is throttled to increase the exhaust pressure.
The flow rate of the exhaust gas flowing back to the intake pipe 2 through the GR passage 11 is increased.
【００１５】図に３０で示すのはエンジン１の電子制御
ユニット（ＥＣＵ）である。ＥＣＵ３０はＣＰＵ２１、
ＲＡＭ２２、ＲＯＭ２３及び入力ポート２４、出力ポー
ト２５を相互に双方向バス２６で接続した構成の公知の
形式のディジタルコンピュータからなり、エンジン１の
燃料噴射弁４を制御して燃料噴射量制御等の通常制御を
行うほか、本実施例ではＮＯX 吸収剤１５の再生操作の
ための燃料噴射制御や吸気シャッターバルブ６、排気シ
ャッターバルブ８の開閉制御を行っている。これらの制
御のためＥＣＵ３０の入力ポートには、エンジン回転
数、アクセル開度、排気温度等の信号がそれぞれ図示し
ないセンサから入力されている。Reference numeral 30 in the drawing denotes an electronic control unit (ECU) of the engine 1. ECU30 is CPU21,
The RAM 22, the ROM 23, the input port 24, and the output port 25 are connected to each other by a bidirectional bus 26, and are composed of a well-known digital computer. In addition to the control, in this embodiment, the fuel injection control for the regeneration operation of the NO X absorbent 15 and the opening / closing control of the intake shutter valve 6 and the exhaust shutter valve 8 are performed. For these controls, signals such as engine speed, accelerator opening, and exhaust temperature are input to input ports of the ECU 30 from sensors (not shown).
【００１６】ＮＯX 吸収剤１５は例えばアルミナを担体
とし、この担体上に例えばカリウムＫ，ナトリウムＮa
，リチウムＬi ，セシウムＣs のようなアルカリ金
属、バリウムＢa , カルシウムＣa のようなアルカリ土
類、ランタンＬa ，イットリウムＹのような希土類から
選ばれた少なくとも一つと、白金Ｐt のような貴金属と
が担持されている。このＮＯX 吸収剤１５は流入する排
気の空燃比がリーンの場合にはＮＯX を吸収し、酸素濃
度が低下するとＮＯX を放出するＮＯX の吸放出作用を
行う。The NO x absorbent 15 uses, for example, alumina as a carrier, and potassium K, sodium Na, etc. are provided on the carrier.
, Lithium Li, alkali metals such as cesium Cs, alkaline earths such as barium Ba and calcium Ca, rare earths such as lanthanum La and yttrium Y, and a noble metal such as platinum Pt. Has been done. This the NO X absorbent 15 absorbs NO X in the case the air-fuel ratio of the exhaust gas flowing is lean, the oxygen concentration is carried out to absorbing and releasing action of the NO X that releases NO X when lowered.
【００１７】なお、上述の排気空燃比とは、ここではＮ
ＯX 吸収剤１５の上流側の排気通路やエンジン燃焼室、
吸気通路等にそれぞれ供給された空気量の合計と燃料の
合計の比を意味するものとする。従って、ＮＯX 吸収剤
１５の上流側排気通路や吸気通路に燃料や還元剤または
空気が供給されない場合には排気空燃比はエンジンの運
転空燃比（エンジン燃焼室内の燃焼における空燃比）と
等しくなる。The exhaust air-fuel ratio mentioned above means here N
The exhaust passage on the upstream side of the O X absorbent 15 and the engine combustion chamber,
It means the ratio of the total amount of air and the total amount of fuel supplied to the intake passage and the like. Therefore, the exhaust air-fuel ratio becomes equal to the operating air-fuel ratio of the engine (air-fuel ratio in combustion in the engine combustion chamber) when fuel, reducing agent or air is not supplied to the exhaust passage or intake passage on the upstream side of the NO x absorbent 15. .
【００１８】本実施例では、ディーゼルエンジンが使用
されているため、通常運転時の排気空燃比はリーンであ
り、ＮＯX 吸収剤１５は排気中のＮＯX の吸収を行う。
また、後述の操作により排気中の酸素濃度が低下する
と、ＮＯX 吸収剤１５は吸収したＮＯX の放出を行う。
この吸放出作用の詳細なメカニズムについては明らかで
ない部分もある。しかし、この吸放出作用は図２に示す
ようなメカニズムで行われているものと考えられる。次
にこのメカニズムについて担体上に白金Ｐt およびバリ
ウムＢa を担持させた場合を例にとって説明するが他の
貴金属、アルカリ金属、アルカリ土類、希土類を用いて
も同様なメカニズムとなる。In this embodiment, since the diesel engine is used, the exhaust air-fuel ratio during normal operation is lean, and the NO X absorbent 15 absorbs NO X in the exhaust.
Further, when the oxygen concentration in the exhaust gas decreases due to the operation described later, the NO X absorbent 15 releases the absorbed NO X.
There are some points where the detailed mechanism of this absorption / release action is not clear. However, it is considered that this absorbing / releasing action is performed by the mechanism shown in FIG. Next, this mechanism will be described by taking as an example the case where platinum Pt and barium Ba are supported on a carrier, but the same mechanism can be obtained by using other noble metals, alkali metals, alkaline earths and rare earths.
【００１９】すなわち、流入排気がかなりリーンになる
と流入排気中の酸素濃度が大巾に増大し、図２(A) に示
されるようにこれら酸素Ｏ2 がＯ2 - またはＯ2-の形で
白金Ｐt の表面に付着する。一方、流入排気中のＮＯは
白金Ｐt の表面上でこのＯ2 - またはＯ2-と反応し、Ｎ
Ｏ2 となる（２ＮＯ＋Ｏ2 →２ＮＯ2 ) 。次いで生成さ
れたＮＯ2 の一部は白金Ｐｔ上で酸化されつつ吸収剤内
に吸収されて酸化バリウムＢａＯと結合しながら図２
(A) に示されるように硝酸イオンＮＯ3 - の形で吸収剤
内に拡散する。このようにしてＮＯX がＮＯX 吸収剤１
５内に吸収される。That is, the inflow exhaust becomes considerably lean.
And the oxygen concentration in the exhaust gas increased significantly, as shown in Figure 2 (A).
As these oxygen O2Is O2 -Or O2-In the form of
It adheres to the surface of platinum Pt. On the other hand, the NO in the exhaust gas is
This O on the surface of platinum Pt2 -Or O2-Reacts with N
O2Becomes (2NO + O2→ 2 NO2 ). Then generated
NO2Part of the inside of the absorbent while being oxidized on platinum Pt
2 while being absorbed by and bound to barium oxide BaO.
As shown in (A), nitrate ion NO3 -Absorbent in the form of
Diffuse in. NO in this wayXIs NOXAbsorbent 1
Absorbed within 5.
【００２０】従って、流入排気中の酸素濃度が高い限り
白金Ｐt の表面でＮＯ2 が生成され、吸収剤のＮＯX 吸
収能力が飽和しない限りＮＯ2 が吸収剤内に吸収されて
硝酸イオンＮＯ3 - が生成される。これに対して流入排
気中の酸素濃度が低下してＮＯ2 の生成量が減少すると
反応が逆方向（ＮＯ3 - →ＮＯ2 ）に進み、吸収剤内の
硝酸イオンＮＯ3 - がＮＯ2 の形で吸収剤から放出され
る。すなわち、流入排気中の酸素濃度が低下するとＮＯ
X 吸収剤１５からＮＯX が放出されることになる。Therefore, NO 2 is produced on the surface of platinum Pt as long as the oxygen concentration in the inflowing exhaust gas is high, and NO 2 is absorbed in the absorbent and nitrate ion NO 3 unless the NO X absorption capacity of the absorbent is saturated. - is generated. In contrast the reaction with the amount of NO 2 oxygen concentration is lowered in the inflowing exhaust gas decreases the reverse (NO 3 - → NO 2) proceeds, the nitrate ions NO 3 of the absorbent - is NO 2 It is released from the absorbent in the form. That is, when the oxygen concentration in the inflowing exhaust gas decreases, NO
NO X is released from the X absorbent 15.
【００２１】一方、流入排気中にＨＣ，ＣＯ等の還元成
分が存在すると、これらの成分は白金Ｐt 上の酸素Ｏ2
- またはＯ2-と反応して酸化され、排気中の酸素を消費
して排気中の酸素濃度を低下させる。また、排気中の酸
素濃度低下によりＮＯX 吸収剤１５から放出されたＮＯ
2 は図２(B) に示すようにＨＣ，ＣＯと反応して還元さ
れる。このようにして白金Ｐt の表面上にＮＯ2 が存在
しなくなると吸収剤から次から次へとＮＯ2 が放出され
る。従って流入排気中のＨＣ，ＣＯ成分が存在すると短
時間のうちにＮＯX 吸収剤１５からＮＯX が放出され、
還元されることになる。On the other hand, when reducing components such as HC and CO are present in the inflowing exhaust gas, these components are oxygen O 2 on platinum Pt.
- or it is reacted with oxide and O 2-, lowering the oxygen concentration in the exhaust to consume oxygen in the exhaust. Further, the NO released from the NO X absorbent 15 due to the decrease in the oxygen concentration in the exhaust gas.
2 is reduced by reacting with HC and CO as shown in Fig. 2 (B). When NO 2 is no longer present on the surface of platinum Pt in this manner, NO 2 is released from the absorbent one after another. Accordingly HC in the inflowing exhaust gas, NO X from the NO X absorbent 15 in a short time when the CO component is present is released,
Will be reduced.
【００２２】すなわち、流入排気中のＨＣ，ＣＯは、ま
ず白金Ｐt 上のＯ2 - またはＯ2-と直ちに反応して酸化
され、次いで白金Ｐt 上のＯ2 - またはＯ2-が消費され
てもまだＨＣ，ＣＯが残っていればこのＨＣ，ＣＯによ
って吸収剤から放出されたＮＯX および機関から排出さ
れたＮＯX が還元される。従って、エンジン運転中にＮ
ＯX の放出、還元（再生）を行うためにＮＯX 吸収剤に
供給すべき還元剤の量は、酸化による酸素消費により排
気中の酸素濃度を充分に低下させるのに必要な量とＮＯ
X 吸収剤１５から放出される全ＮＯX を還元するのに必
要な量との合計となる。しかし、ディーゼルエンジンで
は排気の空燃比は常にリーンであるため、ＮＯX 吸収剤
１５に排気を流しながらＮＯX の放出、還元を行おうと
すると、排気中の酸素を消費するための還元剤の量が非
常に大きくなる。このため、本実施例ではＮＯX 吸収剤
１５の再生時に吸気管２に設けた吸気シャッターバルブ
６を閉弁して外部からエンジン１に吸入される新気の量
を低減するとともに、排気管３に設けた排気シャッター
バルブ８を閉弁してＥＧＲ通路１１を介して吸気シャッ
ターバルブ６の下流側の吸気管に排気を再循環させてＮ
ＯX 吸収剤に流入する酸素の量を低減している。That is, HC and CO in the inflowing exhaust gas first react with O 2 − or O 2− on platinum Pt immediately to be oxidized, and then O 2 − or O 2− on platinum Pt are consumed. the HC, NO X discharged from the released NO X and the engine from the absorbent by CO is reduced even yet HC, any remaining CO is. Therefore, N
The amount of reducing agent to be supplied to the NO x absorbent in order to release and reduce (regenerate) O x is the amount necessary to sufficiently reduce the oxygen concentration in exhaust gas due to oxygen consumption due to oxidation, and the amount of NO x.
This is the sum of the amount required to reduce all the NO x released from the X absorbent 15. However, in a diesel engine, the air-fuel ratio of the exhaust gas is always lean, so if NO x is released or reduced while the exhaust gas is flowing through the NO x absorbent 15, the amount of the reducing agent for consuming oxygen in the exhaust gas is small. Will be very large. Therefore, in this embodiment, the intake shutter valve 6 provided in the intake pipe 2 is closed during regeneration of the NO X absorbent 15 to reduce the amount of fresh air drawn into the engine 1 from the outside, and the exhaust pipe 3 The exhaust shutter valve 8 provided in the intake valve is closed to recirculate the exhaust gas through the EGR passage 11 to the intake pipe downstream of the intake shutter valve 6 to generate N
The amount of oxygen flowing into the O X absorbent is reduced.
【００２３】吸気シャッターバルブ６閉弁時に排気再循
環を行うことにより排気の大部分はＮＯX 吸収剤１５上
流側から吸気シャッターバルブ６下流側に還流され、吸
気シャッターバルブ６から流入する少量の新気と混合し
てエンジン１に吸入されることになり、還流する排気の
量を適宜に設定することによりエンジン１に吸入される
吸気の量を過度に削減することなく新気の流入を大幅に
低減することができる。このため、本実施例によれば吸
気負圧が過度に増大して潤滑油消費量の増大や運転感覚
の悪化が生じることを防止しながら流入する酸素を消費
するための還元剤の量を低減することが可能となる。By performing exhaust gas recirculation when the intake shutter valve 6 is closed, most of the exhaust gas is recirculated from the upstream side of the NO x absorbent 15 to the downstream side of the intake shutter valve 6 and a small amount of new exhaust gas flowing from the intake shutter valve 6. The air is mixed with the air and is sucked into the engine 1. By appropriately setting the amount of the recirculated exhaust gas, the inflow of fresh air can be significantly increased without excessively reducing the amount of the intake air sucked into the engine 1. It can be reduced. Therefore, according to the present embodiment, the amount of the reducing agent for consuming the inflowing oxygen is reduced while preventing the intake negative pressure from excessively increasing to increase the lubricating oil consumption amount and the deterioration of the driving feeling. It becomes possible to do.
【００２４】なお、本実施例では、ＮＯX 吸収剤１５へ
供給する還元剤としてはエンジン１の燃料（軽油）を使
用し、吸気シャッターバルブ６閉弁時に燃料噴射弁４か
ら通常運転時と同様に燃焼室内に燃料を噴射することに
よりＮＯX 吸収剤１５への還元剤供給を行う。この時燃
料噴射弁４からの燃料噴射量は、吸気シャッターバルブ
６から流入する新気中の酸素を全部消費するとともに、
ＮＯX 吸収剤１５に吸収されたＮＯX を還元するのに必
要な量とされる。In this embodiment, the fuel (light oil) of the engine 1 is used as the reducing agent supplied to the NO x absorbent 15, and the intake shutter valve 6 is closed and the fuel injection valve 4 is operated in the same manner as in the normal operation. In addition, the reducing agent is supplied to the NO x absorbent 15 by injecting fuel into the combustion chamber. At this time, the fuel injection amount from the fuel injection valve 4 consumes all oxygen in the fresh air flowing from the intake shutter valve 6, and
The amount is required to reduce the NO X absorbed by the NO X absorbent 15.
【００２５】本実施例では排気再循環を行うことによ
り、吸気シャッターバルブ６のみにより吸気を絞る場合
に較べて新気の流入を約１／３に低減することが可能に
なっており、酸素消費のための還元剤の量もこれに応じ
て低減される。次に、本実施例の排気浄化装置の作用に
ついて説明する。本実施例では、ＥＣＵ３０はＮＯX 吸
収剤１５の再生操作実行条件が成立した時にのみＮＯX
吸収剤１５の再生操作を行う。ここで、本実施例のＮＯ
X 吸収剤の再生実行条件は、（１）運転者がアクセル操
作をしておらず、かつエンジン回転数が所定値以上であ
ること（すなわち、エンジンブレーキの状態であるこ
と）、（２）エンジン排気温度が所定値以上であるこ
と、（３）ＮＯX 吸収剤のＮＯ X 吸収量が所定値以上に
なっていること、であり上記の条件が全て成立している
場合にのみＮＯX 吸収剤の再生操作が行われる。In this embodiment, the exhaust gas recirculation is performed.
When throttled intake air only by the intake shutter valve 6
Compared to, it is possible to reduce the inflow of fresh air to about 1/3
The amount of reducing agent for oxygen consumption
Will be reduced. Next, the operation of the exhaust purification system of this embodiment will be described.
explain about. In this embodiment, the ECU 30 is NOXSucking
NO only when the regenerating operation execution condition of the collecting agent 15 is satisfiedX
The regeneration operation of the absorbent 15 is performed. Here, NO of this embodiment
XThe conditions for executing the regeneration of the absorbent are as follows: (1) The driver operates the accelerator.
Not working, and the engine speed is higher than a specified value.
(That is, the engine is in the brake state)
And), (2) Check that the engine exhaust temperature is above a specified value.
And (3) NOXAbsorbent NO XAbsorption amount exceeds a specified value
That is, all the above conditions are met.
Only if NOXThe absorbent is regenerated.
【００２６】ＮＯX 吸収剤の再生をエンジン減速時にの
み行うのは（上記条件（１））、再生時には吸気シャッ
ターバルブと排気シャッターバルブとを閉じて吸入空気
量を低減する必要があるため、通常運転中に再生を行う
とトルクショックを生じ運転性が悪化するためである。
また、排気温度が所定値以上（上記条件（２））とする
のは、ＮＯX 吸収剤がＮＯX 放出、還元作用の活性化す
る活性化温度に達していることが必要だからである。さ
らに、ＮＯX 吸収剤のＮＯX 吸収量が所定値以上になっ
ていること（上記条件（３））を再生実行条件としてい
るのは頻繁な再生操作を避けて真に再生が必要な場合に
のみ再生操作を行うようにするためである。Since the NO x absorbent is regenerated only when the engine is decelerated (condition (1) above), it is necessary to close the intake shutter valve and the exhaust shutter valve to reduce the intake air amount during regeneration. This is because if regeneration is performed during operation, torque shock will occur and the drivability will deteriorate.
Further, the reason why the exhaust gas temperature is equal to or higher than the predetermined value (the above-mentioned condition (2)) is that the NO X absorbent must reach the activation temperature at which the NO X release and the reducing action are activated. Further, when the NO X absorption of the NO X absorbent that is equal to or higher than a predetermined value (the condition (3)) required to reproduce execution conditions are you doing truly reproduced avoiding frequent regeneration operations This is because only the reproduction operation is performed.
【００２７】なお、ＮＯX 吸収剤のＮＯX 吸収量は、例
えば単位時間当たりのエンジンからのＮＯX の排出量を
予めエンジン負荷（アクセル開度）とエンジン回転数等
の関数としてＥＣＵ３０のＲＯＭ２３に記憶しておき、
一定時間毎にアクセル開度と回転数とから上記関数によ
りＮＯX 排出量を求め、これに一定の係数を乗じたもの
を上記一定時間内のＮＯX 吸収剤のＮＯX 吸収量として
積算することにより求められる。It should be noted, NO X absorption of the NO X absorbent, for example, advance the engine load emissions of the NO X from the engine per unit time (accelerator opening) to ROM23 the ECU30 as a function of engine speed, etc. Remember
Seeking NO X emissions by the function of the accelerator opening and the rotational speed at regular intervals, which in integrating the multiplied by the constant factor as NO X absorption of the NO X absorbent in said predetermined time Required by.
【００２８】上記再生条件の全てが成立している場合、
ＥＣＵ３０は吸気シャッターバルブ６のアクチュエータ
７と排気シャッターバルブ８のアクチュエータ９とを駆
動し、吸気シャッターバルブ６と排気シャッターバルブ
８とを閉弁する。吸気シャッターバルブ６の閉弁により
吸気管２からエンジンに吸入される空気量が絞られ、流
入する新気の量が低減される。また、吸気シャッターバ
ルブ６の閉弁によりシャッターバルブ６下流側の吸気管
負圧が増大するが、同時に排気シャッターバルブ８が閉
弁され、排気圧力が増大するため、ＥＧＲ弁１２の弁体
１２ａには排気管圧力と吸気管負圧との差圧による力が
作用し、負圧アクチュエータ１３の負圧室１３ｂに負圧
が供給されていない場合でも弁体１２ａは弁座から離間
してＥＧＲ通路１１から吸気管２に排気が流入する。When all of the above reproduction conditions are satisfied,
The ECU 30 drives the actuator 7 of the intake shutter valve 6 and the actuator 9 of the exhaust shutter valve 8 to close the intake shutter valve 6 and the exhaust shutter valve 8. By closing the intake shutter valve 6, the amount of air taken into the engine from the intake pipe 2 is reduced, and the amount of fresh air flowing in is reduced. Further, closing the intake shutter valve 6 increases the intake pipe negative pressure on the downstream side of the shutter valve 6, but at the same time the exhaust shutter valve 8 is closed and the exhaust pressure increases, so that the valve body 12a of the EGR valve 12 is closed. Is exerted by a force due to the differential pressure between the exhaust pipe pressure and the intake pipe negative pressure, and the valve body 12a is separated from the valve seat even when the negative pressure is not supplied to the negative pressure chamber 13b of the negative pressure actuator 13. Exhaust gas flows into the intake pipe 2 from 11.
【００２９】このため、吸気シャッターバルブ６を閉じ
て大幅に新気の流入を低減した場合でもエンジンの吸気
負圧は一定値以上には増大せず潤滑油消費の増大や運転
感覚の悪化は生じない。また、ＥＣＵ３０は吸気シャッ
ターバルブ６の閉弁と同時に燃料噴射弁４からの燃料噴
射量を予め設定された量に制御する。この燃料噴射量
は、閉弁状態の吸気シャッターバルブ６を通過して流入
する新気中の全酸素を消費するのに必要な量と、ＮＯX
吸収剤１５に吸収されたＮＯX を還元するのに必要な量
との和に設定される。なお、ＮＯX 吸収剤に吸収された
ＮＯX の還元に必要とされる燃料量は新気中の酸素を消
費するのに必要とされる燃料量に較べて少なく、ＮＯX
吸収剤再生時の燃料（還元剤）消費量は実質的には流入
する新気の量により決定される。また、吸気シャッター
バルブ６閉弁時にはバルブ６を通る流れはチョークして
おり流入する新気の量は吸気マニホルドの負圧により決
まるため、本実施例ではエンジン回転数にかかわらず略
一定流量となる。このため、ＮＯX 吸収剤１５再生時の
燃料噴射弁４からの燃料噴射量はエンジン回転数にかか
わらず一定値に設定することができる。Therefore, even when the intake shutter valve 6 is closed to greatly reduce the inflow of fresh air, the intake negative pressure of the engine does not increase above a certain value, and the consumption of lubricating oil increases and the driving feeling deteriorates. Absent. Further, the ECU 30 controls the fuel injection amount from the fuel injection valve 4 to a preset amount at the same time when the intake shutter valve 6 is closed. This fuel injection amount is the amount necessary to consume all the oxygen in the fresh air flowing through the intake shutter valve 6 in the closed state, and NO X.
It is set to the sum of the amount required to reduce the NO X absorbed by the absorbent 15. The fuel amount required for reduction of the NO X absorbed in the NO X absorbent is less than the amount of fuel required to consume the oxygen in the fresh air, NO X
The amount of fuel (reducing agent) consumed at the time of regeneration of the absorbent is substantially determined by the amount of fresh air flowing in. Further, when the intake shutter valve 6 is closed, the flow through the valve 6 is choked, and the amount of fresh air that flows in is determined by the negative pressure of the intake manifold. Therefore, in this embodiment, the flow rate is substantially constant regardless of the engine speed. . Therefore, the amount of fuel injected from the fuel injection valve 4 when the NO X absorbent 15 is regenerated can be set to a constant value regardless of the engine speed.
【００３０】上記のように、新気の量を低減して燃焼室
内に燃料を噴射することにより、噴射された燃料は気筒
内で燃焼するとともに、気筒内で燃焼しなかった燃料も
ＮＯ X 吸収剤の触媒作用により燃焼するため排気中の酸
素が消費され、上述のＮＯX吸収剤からのＮＯX の放
出、還元が行われる。上記のＮＯX 吸収剤の再生操作は
再生操作が所定時間実行された場合、または運転状態の
変化により上記の再生操作実行条件が成立しなくなった
場合に終了する。再生操作が終了したと判断された場
合、ＥＣＵ３０は吸気シャッターバルブ６と排気シャッ
ターバルブ８とを開弁し、通常の燃料噴射制御を再開す
る。これにより、ＥＧＲ弁１２は閉弁し、エンジン１は
通常の運転状態に復帰する。As described above, the amount of fresh air is reduced and the combustion chamber
By injecting fuel into the cylinder, the injected fuel is
Fuel that did not burn in the cylinder
NO XAcid in the exhaust gas because it burns due to the catalytic action of the absorbent
Element is consumed, and the above NOXNO from absorbentXRelease of
Withdrawals and returns are made. NO aboveXRegeneration operation of absorbent
When the regeneration operation is performed for a predetermined time, or when the
Due to the change, the above playback operation execution conditions are no longer met
To end. If it is determined that the playback operation has finished,
ECU 30, the intake shutter valve 6 and the exhaust shutter are
Open the target valve 8 and restart the normal fuel injection control.
It As a result, the EGR valve 12 is closed and the engine 1 is
Return to normal operating conditions.
【００３１】なお、上記の実施例ではＮＯX 吸収剤再生
時の燃料噴射量は一定値に制御しているが、実際には排
気とともに噴射された燃料の一部も吸気側に還流しＮＯ
X 吸収剤再生操作開始時から時間が経過するにつれて必
要とされる燃料の量は減少する。このため、ＮＯX 吸収
剤１５の下流側の排気管に排気中の酸素濃度を検出する
酸素濃度センサを配置し、ＮＯX 吸収剤１５を通過する
排気中の酸素濃度が所定レベルに維持されるように（排
気空燃比がかなりリッチになるように）ＮＯX吸収剤再
生時の燃料噴射量をフィードバック制御するようにすれ
ば燃料供給量を低減することができる。In the above embodiment, the fuel injection amount at the time of regeneration of the NO X absorbent is controlled to a constant value, but in reality, a part of the fuel injected together with the exhaust gas also recirculates to the intake side and NO.
The amount of fuel required decreases as time passes from the start of the X- absorbent regeneration operation. Therefore, the oxygen concentration in the exhaust oxygen concentration sensor for detecting oxygen concentration in the exhaust to the exhaust pipe on the downstream side of the NO X absorbent 15 is disposed, passes through the NO X absorbent 15 is maintained at a predetermined level Thus, the fuel supply amount can be reduced by feedback-controlling the fuel injection amount at the time of regeneration of the NO X absorbent (so that the exhaust air-fuel ratio becomes considerably rich).
【００３２】また、上記実施例では燃料噴射弁４からの
燃料噴射によりＮＯX 吸収剤に還元剤（燃料）を供給し
ているが別途還元剤供給装置を設けてＮＯX 吸収剤に還
元剤を供給するようにしてもよい。この場合、例えば、
吸気管２のシャッターバルブ６下流側に開口する還元剤
供給ノズルを設け、ＮＯX 吸収剤再生時に吸気管負圧を
利用して吸気管内に還元剤を供給したり、或いはＮＯX
吸収剤上流側の排気管に供給ノズルを設けポンプ等の加
圧手段により排気管内に還元剤を噴射するようにするこ
ともできる。Further, in the above embodiment, the reducing agent (fuel) is supplied to the NO X absorbent by the fuel injection from the fuel injection valve 4, but a reducing agent supply device is separately provided to supply the reducing agent to the NO X absorbent. It may be supplied. In this case, for example,
A reducing agent supply nozzle opening to shutter valve 6 downstream of the intake pipe 2 is provided, and supplies the reducing agent into the intake pipe by using an intake pipe negative pressure during the NO X absorbent regeneration, or NO X
It is also possible to provide a supply nozzle in the exhaust pipe upstream of the absorbent and inject the reducing agent into the exhaust pipe by a pressurizing means such as a pump.
【００３３】次に図３に本発明の別の実施例を示す。図
３において、図２の実施例と同一の要素は同じ参照符号
で示している。図２の実施例では、ＥＧＲ通路１１はＮ
ＯX吸収剤１５の上流側の排気通路に接続されていた
が、本実施例ではＥＧＲ通路１１はＮＯX 吸収剤１５の
下流側の排気通路に接続され、ＮＯX 吸収剤１５と排気
シャッターバルブ８との間の部分から吸気側に排気を還
流させている点が図２の実施例と相違している。Next, FIG. 3 shows another embodiment of the present invention. 3, the same elements as those of the embodiment of FIG. 2 are designated by the same reference numerals. In the embodiment of FIG. 2, the EGR passage 11 has N
O X absorbent 15 had been connected to the exhaust passage upstream of, EGR passage 11 in this embodiment is connected to an exhaust passage downstream of the NO X absorbent 15, the exhaust shutter valve as the NO X absorbent 15 2 is different from the embodiment of FIG. 2 in that exhaust gas is recirculated from a portion between 8 and 8 to the intake side.
【００３４】図２の実施例では、例えば吸入圧力の低下
による圧縮不足のためエンジン１で燃焼が生じなかった
ような場合には供給された燃料の全量をＮＯX 吸収剤１
５で燃焼させる必要があり、排気温度等の条件によって
は燃料のＨＣ成分が未燃焼のまま下流側に流出する可能
性がある。本実施例ではＮＯX 吸収剤１５下流側から排
気を取り出して吸気側に還流させるようにしたことによ
り、ＮＯX 吸収剤１５を通過した未燃焼のＨＣ成分を排
気とともに還流させることができ、ＮＯX 吸収剤１５の
再生時に燃料を有効に使用することができる。In the embodiment of FIG. 2, for example, when combustion does not occur in the engine 1 due to insufficient compression due to a decrease in suction pressure, the total amount of fuel supplied is changed to NO x absorbent 1.
Therefore, the HC component of the fuel may flow out to the downstream side without being burned depending on the conditions such as the exhaust temperature. In this embodiment, since the exhaust gas is taken out from the downstream side of the NO x absorbent 15 and is recirculated to the intake side, the unburned HC component that has passed through the NO x absorbent 15 can be recirculated together with the exhaust gas. The fuel can be effectively used when the X absorbent 15 is regenerated.
【００３５】さらに、図２の実施例では、ＮＯX 吸収剤
１５を通る排気の流れを確保するために、吸気シャッタ
ーバルブ６からある程度の新気を導入し、排気シャッタ
ーバルブ８から新気の量に相当する量の排気を外部に流
出させる必要があるが、本実施例ではＮＯX 吸収剤１５
下流側から排気を取り出して吸気側に還流させるように
したため、吸気シャッターバルブ６から導入する新気の
量にかかわらずＮＯX吸収剤１５を通る排気の流れを確
保することができる。このため、本実施例では、図２の
実施例よりさらに大幅に新気の量を低減することが可能
となり還元剤消費量がさらに低減される利点がある。な
お、本実施例におけるＮＯX 吸収剤１５の再生操作は図
２の実施例と略同一であるため、ここでは説明を省略す
る。Further, in the embodiment of FIG. 2, in order to secure the flow of exhaust gas through the NO x absorbent 15, a certain amount of fresh air is introduced from the intake shutter valve 6 and the amount of fresh air from the exhaust shutter valve 8 is increased. it is necessary to flow out the corresponding amount of the exhaust to the outside, but in this embodiment the NO X absorbent 15
Since the exhaust gas is taken out from the downstream side and is recirculated to the intake side, the flow of the exhaust gas through the NO x absorbent 15 can be secured regardless of the amount of fresh air introduced from the intake shutter valve 6. Therefore, the present embodiment has an advantage that the amount of fresh air can be reduced significantly more than the embodiment of FIG. 2 and the reducing agent consumption amount can be further reduced. The regeneration operation of the NO X absorbent 15 in this embodiment is substantially the same as that in the embodiment shown in FIG. 2, and therefore its explanation is omitted here.
【００３６】以上、本発明の内燃機関の排気浄化装置を
ディーゼルエンジンに適用した場合について説明した
が、本発明はディーゼルエンジンにのみ適用が限定され
るわけではなく、希薄燃焼を行うガソリンエンジン等に
も適用可能であることは言うまでもない。The case where the exhaust gas purification apparatus for an internal combustion engine according to the present invention is applied to a diesel engine has been described above. However, the present invention is not limited to application to a diesel engine, but to a gasoline engine that performs lean combustion. It goes without saying that is also applicable.
【００３７】[0037]
【発明の効果】本発明の内燃機関の排気浄化装置は、Ｎ
ＯX 吸収剤の再生操作時に機関排気の少なくとも一部を
機関吸気側に還流させる手段を設けたことにより、機関
潤滑油消費の増大や運転感覚の悪化を生じることなくＮ
ＯX 吸収剤再生時の還元剤消費量の大幅な低減が可能と
なる効果を奏する。The exhaust gas purifying apparatus for an internal combustion engine according to the present invention has N
By providing a means for recirculating at least a part of the engine exhaust gas to the engine intake side during the regeneration operation of the O X absorbent, it is possible to increase the consumption of the engine lubricating oil and the deterioration of the driving feeling.
O X absorbent significant reduction of the reducing agent consumption during reproduction the effect that can be achieved.
【図１】本発明の排気浄化装置の一実施例を示す図であ
る。FIG. 1 is a diagram showing an embodiment of an exhaust emission control device of the present invention.
【図２】ＮＯX 吸収剤のＮＯX 吸放出作用を説明する図
である。FIG. 2 is a diagram illustrating the NO X absorption and release action of a NO X absorbent.
【図３】本発明の排気浄化装置の、図１とは別の実施例
を示す図である。FIG. 3 is a diagram showing an embodiment of the exhaust emission control device of the present invention different from that of FIG.
１…ディーゼルエンジン ２…エンジン吸気管 ３…エンジン排気管 ６…吸気シャッターバルブ ８…排気シャッターバルブ １１…ＥＧＲ通路 １２…ＥＧＲ弁 １５…ＮＯX 吸収剤 ３０…電子制御ユニット1 ... Diesel engine 2 ... Engine intake pipe 3 ... Engine exhaust pipe 6 ... Intake shutter valve 8 ... Exhaust shutter valve 11 ... EGR passage 12 ... EGR valve 15 ... NO X absorbent 30 ... Electronic control unit
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｆ０２Ｄ 9/02 ３４１ Ｇ 9/04 Ｅ Ｆ０２Ｍ 25/07 Ｂ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification number Office reference number FI technical display location F02D 9/02 341 G 9/04 E F02M 25/07 B
Claims (1)
気通路に、流入排気の空燃比がリーンのときにＮＯX を
吸収し流入排気の酸素濃度が低下したときに吸収したＮ
ＯX を放出するＮＯX 吸収剤を配置して排気中のＮＯX
を吸収させ、前記ＮＯX 吸収剤に還元剤を供給すること
により排気中の酸素濃度を低下させてＮＯX 吸収剤から
吸収したＮＯX を放出させるとともに該ＮＯX を還元浄
化する内燃機関の排気浄化装置において、前記ＮＯX 吸
収剤に還元剤を供給する際に、機関排気の少なくとも一
部を機関吸気通路に還流させる手段を備えたことを特徴
とする内燃機関の排気浄化装置。1. The exhaust passage of an internal combustion engine that burns lean air-fuel ratio absorbs NO x when the air-fuel ratio of the inflowing exhaust gas is lean and absorbs N x when the oxygen concentration of the inflowing exhaust gas decreases.
NO X absorbent that releases O X is placed and NO X in exhaust gas
To absorb the exhaust of an internal combustion engine with the release of NO X absorbed and thus reduce the oxygen concentration in the exhaust gas the NO X absorbent to reduce and purify the NO X by feeding a reducing agent to the the NO X absorbent in purifier, the NO in the X absorbent when supplying a reducing agent, an exhaust purification device for an internal combustion engine, characterized in that it comprises means for recirculating at least a portion of the engine exhaust to an engine intake passage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5104347A JP2722990B2 (en) | 1993-04-30 | 1993-04-30 | Exhaust gas purification device for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5104347A JP2722990B2 (en) | 1993-04-30 | 1993-04-30 | Exhaust gas purification device for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06317142A true JPH06317142A (en) | 1994-11-15 |
| JP2722990B2 JP2722990B2 (en) | 1998-03-09 |
Family
ID=14378363
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5104347A Expired - Lifetime JP2722990B2 (en) | 1993-04-30 | 1993-04-30 | Exhaust gas purification device for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2722990B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5697211A (en) * | 1994-12-21 | 1997-12-16 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device |
| EP0764771A3 (en) * | 1995-09-20 | 1998-02-25 | Toyota Jidosha Kabushiki Kaisha | Compression ignition type engine |
| EP0872633A3 (en) * | 1997-04-18 | 1999-03-24 | Volkswagen Aktiengesellschaft | Process for the reduction of nitrogen oxides in the exhaust gas of an internal combustion engine |
| JP2002256863A (en) * | 2001-03-02 | 2002-09-11 | Mitsubishi Motors Corp | Device for suppressing deterioration of catalyst in internal combustion engine |
| WO2003069137A1 (en) * | 2002-02-12 | 2003-08-21 | Isuzu Motors Limited | Exhaust gas decontamination system and method of exhaust gas decontamination |
| JP2007327389A (en) * | 2006-06-07 | 2007-12-20 | Mitsubishi Heavy Ind Ltd | Exhaust gas treatment device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001303934A (en) | 1998-06-23 | 2001-10-31 | Toyota Motor Corp | Exhaust emission control device for internal combustion engine |
-
1993
- 1993-04-30 JP JP5104347A patent/JP2722990B2/en not_active Expired - Lifetime
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5697211A (en) * | 1994-12-21 | 1997-12-16 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device |
| EP0764771A3 (en) * | 1995-09-20 | 1998-02-25 | Toyota Jidosha Kabushiki Kaisha | Compression ignition type engine |
| US5826427A (en) * | 1995-09-20 | 1998-10-27 | Toyota Jidosha Kabushiki Kaisha | Compression ignition type engine |
| EP0872633A3 (en) * | 1997-04-18 | 1999-03-24 | Volkswagen Aktiengesellschaft | Process for the reduction of nitrogen oxides in the exhaust gas of an internal combustion engine |
| JP2002256863A (en) * | 2001-03-02 | 2002-09-11 | Mitsubishi Motors Corp | Device for suppressing deterioration of catalyst in internal combustion engine |
| WO2003069137A1 (en) * | 2002-02-12 | 2003-08-21 | Isuzu Motors Limited | Exhaust gas decontamination system and method of exhaust gas decontamination |
| US7448203B2 (en) | 2002-02-12 | 2008-11-11 | Isuzu Motors Limited | Exhaust gas decontamination system and method of exhaust gas decontamination |
| JP2007327389A (en) * | 2006-06-07 | 2007-12-20 | Mitsubishi Heavy Ind Ltd | Exhaust gas treatment device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2722990B2 (en) | 1998-03-09 |
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