JP3378044B2 - Engine exhaust purification device - Google Patents
Engine exhaust purification deviceInfo
- Publication number
- JP3378044B2 JP3378044B2 JP09658493A JP9658493A JP3378044B2 JP 3378044 B2 JP3378044 B2 JP 3378044B2 JP 09658493 A JP09658493 A JP 09658493A JP 9658493 A JP9658493 A JP 9658493A JP 3378044 B2 JP3378044 B2 JP 3378044B2
- Authority
- JP
- Japan
- Prior art keywords
- fuel ratio
- air
- temperature
- exhaust gas
- gas temperature
- 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.)
- Expired - Fee Related
Links
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は、エンジンの排気浄化装
置に関する。
【０００２】
【従来技術】エンジンの排気浄化装置には、特開平１−
３１０７４２号公報に示すように、排気系に銅系ゼオラ
イトからなるＮＯX 触媒を備えたものがある。このもの
においては、ＮＯX 触媒の浄化率は、該ＮＯX 触媒に流
入する排気ガス温度によってのみ変化し、空燃比の変化
によっては変化しないことになっている。このため、こ
の排気浄化装置においては、触媒に流入する排気ガス温
度を、空燃比の変化にかかわりなく、一定の最適なもの
保持できれば、最大ＮＯX 浄化率を得ることができるこ
とになる。
【０００３】ところで、近時、希薄燃焼（リ−ンバ−
ン）エンジンを搭載した実車に装備して酸素高濃度雰囲
気下でＮＯX を浄化する場合、上記銅系ゼオライトから
なるＮＯX 触媒では、ＮＯX 浄化率が低下せざるを得な
いことから、貴金属系ＮＯX 触媒が開発されつつある。
【０００４】
【発明が解決しようとする課題】しかし、本発明者は、
貴金属系ＮＯX 触媒に関し、空燃比がリ−ンなほど、最
大ＮＯX 浄化率を得るための排気ガス温度（実質的に触
媒温度と同じ）が低くなる特性を見出した（図２参
照）。したがって、トルクが欲しいために、リ−ンバ−
ンエンジンの運転状態を理論空燃比としている場合にお
いて、運転状態が半暖機時、定速走行等して、排気ガス
温度が低いようなときは、当該排気ガス温度は、理論空
燃比下での最大ＮＯX 浄化率を得るための排気ガス温度
よりもずれているため、ＮＯX 浄化率は低下せざるを得
ない。本発明は上記実情に鑑みてなされたもので、その
目的は、半暖機時等のように排気ガス温度が低いような
ときであっても、ＮＯX 浄化率が低下することを防止で
きるエンジンの排気浄化装置を提供することにある。
【０００５】
【課題を解決するための手段、作用】上記目的を達成す
るため本発明にあっては、理論空燃比の運転領域を備え
るエンジンの排気系に備えられ、排気ガス温度が低くな
るほど最大ＮＯｘ浄化率を実現するための空燃比がリー
ンになる特性を有する貴金属系ＮＯｘ触媒と、空燃比を
変更する空燃比変更手段と、前記ＮＯｘ触媒上流側の排
気ガス温度を検出する温度検出手段と、目標空燃比を検
出する目標空燃比検出手段と、前記目標空燃比検出手段
からの信号に基づき、理論空燃比の運転領域に属すると
判断したときであって、前記温度検出手段からの信号に
基づき、排気ガス温度が、理論空燃比において最大ＮＯ
ｘ浄化率を実現するための温度から該温度よりも低い所
定温度までの所定の温度範囲にあると判断したとき、前
記空燃比変更手段を制御して、空燃比を理論空燃比より
も所定値リ−ン側へ変更する制御手段と、を備える、こ
とを特徴とするエンジンの排気浄化装置とした構成とし
てある。上述の構成により、運転状態を理論空燃比とす
る場合において、運転状態が半暖機時、定速走行等し
て、排気ガス温度が、理論空燃比において最大ＮＯｘ浄
化率を実現するための温度から該温度よりも低い所定温
度までの所定の温度範囲にあるようなときには、空燃比
が理論空燃比よりも所定値リ−ン側へ変更されることに
なり、トルク低下を問題にすることなく、当該排気ガス
温度にとって、ＮＯｘ浄化性能の観点から最適な空燃比
が得られることになる。このため、半暖機時等のように
排気ガス温度が低いようなときであっても、ＮＯｘ浄化
率が低下することを的確に防止できることになる。
【０００６】
【実施例】以下、本発明の実施例を図面に基づいて説明
する。図１において、１は４サイクル往復動型とされた
オット−式のリ−ンバ−ンエンジンで、該エンジン１
は、図５に示す如く、理論空燃比（λ＝１）、該理論空
燃比よりもリ−ンなリ−ン空燃比等の運転領域を有し、
既知の如く、エンジンの運転状態に応じて、理論空燃
比、リ−ン空燃比等で運転されることになっている。
【０００７】上記エンジン１には、吸気弁３を介して燃
焼室２に通じる吸気通路５と、排気弁４を介して燃焼室
２に通じる排気通路６とが設けられている。
【０００８】上記吸気通路５には、上流側から下流側に
向けて順に、エアフロメ−タ７、スロットル弁８、燃料
噴射弁９が配設されている。
【０００９】一方、上記排気通路６には、上流側から下
流側に向けて順に、空燃比センサ１１、ＮＯX 触媒１０
が配設されている。上記貴金属系ＮＯX 触媒１０として
は、例えばＰｔ，Ｉｒ等の貴金属をゼオライトが担持す
る貴金属系ゼオライト触媒等が用いられており、このＮ
ＯX 触媒１０は、空燃比リ−ン状態で運転されて、排気
ガスが酸素高濃度雰囲気下であっても、ＮＯX をＨＣ、
ＣＯと共に浄化できる機能を有している。
【００１０】図１中、符号Ｕはマイクロコンピュ−タに
よって構成された制御ユニットで、該制御ユニットＵに
は、前記エアフロメ−タ７の他に、センサ１２〜１４か
らの信号が入力されることになっている。上記センサ１
２は、ＮＯX 触媒入口の排気ガス温度を検出する温度セ
ンサである。上記センサ１３は、エンジン回転数を検出
する回転数センサである。上記センサ１４は、エンジン
冷却水温を検出する水温センサである。一方、制御ユニ
ットＵからは、燃料噴射弁９に対して制御信号が出力さ
れることになっている。
【００１１】次に、上記制御ユニットＵの制御内容の概
略について図２に基づいて説明する。先ず、制御ユニッ
トＵの制御内容の理解を容易にするために本発明者が見
出したＮＯX 触媒１０の特性について説明する。貴金属
系ＮＯX 触媒１０に関しては、図２に示すように（ｆ0
は空燃比Ａ／Ｆ１４．７、ｆ1 はＡ／Ｆ＝１５、ｆ2 は
Ａ／Ｆ＝１６、ｆ3 はＡ／Ｆ＝１７、ｆ4 はＡ／Ｆ＝２
２の特性線を示す）、空燃比がリ−ンなほど、最大ＮＯ
X 浄化率を得るための排気ガス温度が低くなる特性を示
した。このため、リ−ンバ−ンエンジンの運転状態を理
論空燃比としている場合において、運転状態が半暖機
時、定速走行等して、排気ガス温度が低いようなときは
（例えば、２３０℃）、当該排気ガス温度が、理論空燃
比下での最大ＮＯX 浄化率を得るための排気ガス温度よ
りもずれるため、ＮＯX 浄化率が低下することが判明し
た（図２参照）。
【００１２】そこで、本発明においては、理論空燃比下
での最大ＮＯX 浄化率を得るための排気ガス温度とのず
れを是正すべく、空燃比を理論空燃比よりも所定値リ−
ン側へ変更して、当該排気ガス温度にとって、ＮＯX 浄
化性能の観点から最適な空燃比とし、これにより、半暖
機時等のように排気ガス温度が低いようなときであって
も、ＮＯX 浄化率が低下することを防止しようとしてい
る。具体的には、図２に示すように、理論空燃比よりも
ややリ−ンな空燃比の下で、その最大ＮＯX 浄化率を得
るための排気ガス温度付近で所定範囲Ｋ0 〜Ｋ1 を区切
り、その所定範囲Ｋ0 〜Ｋ1 に現実の排気ガス温度が属
するときに、その所定範囲で最大ＮＯX 浄化率を得られ
るように、制御ユニットＵが燃料噴射弁９を制御して空
燃比を変更することとしている（図２中の実施例におい
ては、ｆ1 ：Ａ／Ｆ＝１５、ｆ2 ：Ａ／Ｆ＝１６）。
【００１３】次に、上記制御ユニットＵの制御内容を図
３に示すフローチャートを参照しつつ説明する。尚、以
下の説明でＳはステップを示す。先ず、Ｓ１において、
エンジン回転数Ｎｅ、吸入空気量Ｃｅ、現実の排気ガス
温度Ｔ1 が読込まれ、Ｓ２において、エンジン回転数Ｎ
ｅ、吸入空気量Ｃｅ等に基づいて目標空燃比が求めら
れ、その目標空燃比が理論空燃比（λ＝１）か否かが判
別される。理論空燃比で運転しているときに生じる問題
だからである。したがって、Ｓ２がＹＥＳのときには、
本制御を行うべく、Ｓ３に進むことになる。
【００１４】Ｓ３においては、現実の排気ガス温度Ｔ1
が前述の所定範囲Ｋ0 〜Ｋ1 に属するか否かが判別され
る。これは、仮に、排気ガス温度Ｔ1 の下で高い（略最
大）ＮＯX 浄化率を得るように空燃比を変更しても、ト
ルク低下が問題にならない程度か否かを判断するために
行われる。したがって、Ｓ３がＮＯのときには、トルク
の低下等から対象外であるとして、Ｓ４において、目標
空燃比が理論空燃比にセットされる一方、Ｓ３がＹＥＳ
のときには、トルク低下が問題にならないとして、空燃
比は目標空燃比からリ−ン（図２中、ｆ1 ：Ａ／Ｆ＝１
５、ｆ2 ：Ａ／Ｆ＝１６等）に移行される。これによ
り、半暖機時等のように排気ガス温度が低いようなとき
であっても、トルク低下をほとんど問題せずに、現実の
排気ガス温度Ｔ1 の下で高いＮＯX 浄化率を得ることが
できることになる。
【００１５】一方、前記Ｓ２がＮＯのときには、本制御
の対象外であるとして、Ｓ６に進んで、エンジンの冷却
水温ＷＴが読込まれ、次のＳ７において、Ｓ６の水温Ｗ
Ｔにおける希薄燃焼限界Ｌ／Ｌの空燃比Ａ／Ｆ0 が、図
４に基づいて算出される。続いて、Ｓ８において、現実
の排気ガス温度Ｔ1 の下で最大ＮＯX 浄化率を得ること
ができる空燃比Ａ／Ｆ1 が表１に基づいて算出される。
この表１の内容は、Ｔ1 が低いほど、空燃比Ａ／Ｆ1 が
リ−ンになる傾向となっている。
【００１６】
【表１】
【００１７】次に、Ｓ９において、Ｓ８のＡ／Ｆ1 がＳ
７のＡ／Ｆ0 よりも小さい（リッチ）か否かが判別され
る。これは、最大ＮＯX 浄化率を得ることを目的として
はいるものの、前提として、燃焼できるようにすること
を確保するために行われる。したがって、Ｓ９がＹＥＳ
のときには、Ｓ１０において、目標空燃比がＡ／Ｆ1に
セットされて現実の排気ガス温度Ｔ1 の下で最大ＮＯX
浄化率が得られる一方、Ｓ９がＮＯのときには、前提と
して燃焼を確保すべく、Ｓ１１において、目標空燃比は
前記Ｓ７のＡ／Ｆ0 にセットされる。
【００１８】
【発明の効果】本発明は以上述べたように、半暖機時等
のように排気ガス温度が低いようなときであっても、Ｎ
Ｏｘ浄化率が低下することを的確に防止できる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine exhaust purification device. 2. Description of the Related Art An exhaust gas purifying apparatus for an engine is disclosed in
As shown in 310742 JP, it is provided with a NO X catalyst comprising a copper-based zeolite in an exhaust system. In this compound, the purification rate of the NO X catalyst is only varied by the exhaust gas temperature flowing into the NO X catalyst, and is not changed by a change in air-fuel ratio. Therefore, in the exhaust purification apparatus, the exhaust gas temperature flowing into the catalyst, irrespective of the change in the air-fuel ratio, if maintained constant optimal, so that it is possible to obtain the maximum NO X purification rate. [0003] Recently, lean burn (lean bar)
If down) equipped to an actual vehicle equipped with an engine to purify the NO X in an oxygen-rich atmosphere, the NO X catalyst made of the copper-based zeolite, NO X purification rate because decrease inevitably, precious metal systems NO X catalyst are being developed. [0004] However, the inventor of the present invention
Relates noble metal NO X catalyst, the air-fuel ratio is re - as a down, the maximum NO X purification rate exhaust gas temperature for obtaining a (substantially the same as the catalyst temperature) is found properties to be low (see Fig. 2). Therefore, to get the torque,
When the operating state of the engine is the stoichiometric air-fuel ratio and the operating state is half warm-up, running at a constant speed, etc., and the exhaust gas temperature is low, the exhaust gas temperature becomes lower than the stoichiometric air-fuel ratio. maximum NO because X is deviated from the exhaust gas temperature in order to obtain the purification rate, NO X purification rate decrease inevitably the. The present invention has been made in view of the above, the engine that purpose, even when the exhaust gas temperature as isochronous semi warm-up is low, such as, that can prevent the NO X purification rate decreases It is an object of the present invention to provide an exhaust gas purification device. In order to achieve the above object, the present invention provides an exhaust system for an engine having an operating range of a stoichiometric air-fuel ratio, wherein the lower the exhaust gas temperature, the greater the maximum. A noble metal-based NOx catalyst having a characteristic of making the air-fuel ratio lean for realizing the NOx purification rate, air-fuel ratio changing means for changing the air-fuel ratio, and temperature detecting means for detecting the exhaust gas temperature on the upstream side of the NOx catalyst. Based on a signal from the target air-fuel ratio detecting means for detecting a target air-fuel ratio and a signal from the target air-fuel ratio detecting means, when it is determined that the target air-fuel ratio belongs to an operating range of the stoichiometric air-fuel ratio, and a signal from the temperature detecting means Exhaust gas temperature is the maximum NO at the stoichiometric air-fuel ratio.
x When it is determined that the temperature is within a predetermined temperature range from a temperature for realizing the purification rate to a predetermined temperature lower than the temperature, the air-fuel ratio changing means is controlled to set the air-fuel ratio to a predetermined value higher than the stoichiometric air-fuel ratio. And control means for changing to the lean side. With the configuration described above, when the operating state is the stoichiometric air-fuel ratio, the operating state is half warm-up, running at a constant speed, etc., and the exhaust gas temperature becomes the temperature for realizing the maximum NOx purification rate at the stoichiometric air-fuel ratio. When the air-fuel ratio is within a predetermined temperature range from the predetermined temperature to a predetermined temperature lower than the temperature, the air-fuel ratio is changed to a predetermined value lean side from the stoichiometric air-fuel ratio, and the decrease in torque does not matter. Therefore, an optimum air-fuel ratio can be obtained from the viewpoint of NOx purification performance for the exhaust gas temperature. For this reason, even when the exhaust gas temperature is low, such as when the engine is half warmed up, it is possible to accurately prevent the NOx purification rate from decreasing. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a 4-cycle reciprocating otto-type lean burn engine.
Has an operating range such as a stoichiometric air-fuel ratio (λ = 1) and a lean air-fuel ratio leaner than the stoichiometric air-fuel ratio, as shown in FIG.
As is known, the engine is operated at a stoichiometric air-fuel ratio, a lean air-fuel ratio, or the like according to the operating state of the engine. The engine 1 is provided with an intake passage 5 communicating with the combustion chamber 2 via the intake valve 3 and an exhaust passage 6 communicating with the combustion chamber 2 via the exhaust valve 4. In the intake passage 5, an air flow meter 7, a throttle valve 8, and a fuel injection valve 9 are arranged in order from the upstream side to the downstream side. On the other hand, in the exhaust passage 6 is composed of, in order from the upstream side toward the downstream side, the air-fuel ratio sensor 11, NO X catalyst 10
Are arranged. As the noble metal-based NO X catalyst 10, a noble metal-based zeolite catalyst or the like in which zeolite supports a noble metal such as Pt, Ir, or the like is used.
O X catalyst 10, the air-fuel ratio Li - are operated in down state, even the exhaust gas even under high-oxygen concentration atmosphere, the NO X HC,
It has the function of purifying with CO. In FIG. 1, reference numeral U denotes a control unit constituted by a microcomputer, to which signals from sensors 12 to 14 as well as the air flow meter 7 are inputted. It has become. The above sensor 1
2 is a temperature sensor for detecting the exhaust gas temperature of the NO X catalyst inlet. The sensor 13 is a rotation speed sensor that detects the engine rotation speed. The sensor 14 is a water temperature sensor that detects an engine cooling water temperature. On the other hand, the control unit U outputs a control signal to the fuel injection valve 9. Next, an outline of the control contents of the control unit U will be described with reference to FIG. First, the characteristics of the NO X catalyst 10 found by the present inventor to facilitate understanding of the control contents of the control unit U will be described. For the noble metal NO X catalyst 10, as shown in FIG. 2 (f 0
Is the air-fuel ratio A / F 14.7, f 1 is A / F = 15, f 2 is A / F = 16, f 3 is A / F = 17, and f 4 is A / F = 2.
2 indicates that the air-fuel ratio is leaner, the maximum NO
The characteristics showed that the exhaust gas temperature for obtaining the X purification rate was reduced. For this reason, when the operating state of the lean burn engine is the stoichiometric air-fuel ratio and the operating state is half warm-up, running at a constant speed, etc., and the exhaust gas temperature is low (for example, 230 ° C.). ), It has been found that the exhaust gas temperature deviates from the exhaust gas temperature for obtaining the maximum NO X purification rate under the stoichiometric air-fuel ratio, so that the NO X purification rate decreases (see FIG. 2). Therefore, in the present invention, in order to correct the deviation from the exhaust gas temperature for obtaining the maximum NO X purification rate under the stoichiometric air-fuel ratio, the air-fuel ratio is set to a predetermined value smaller than the stoichiometric air-fuel ratio.
Change to down side, for the exhaust gas temperature, the optimum air-fuel ratio in terms of the NO X purification performance, thereby, even when the exhaust gas temperature as isochronous semi warm-up is low, such as, NO X purification rate is attempting to prevent the decrease. Specifically, as shown in FIG. 2, a predetermined range K 0 to K 1 is set near an exhaust gas temperature for obtaining the maximum NO X purification rate under an air-fuel ratio slightly leaner than the stoichiometric air-fuel ratio. When the actual exhaust gas temperature belongs to the predetermined range K 0 to K 1 , the control unit U controls the fuel injection valve 9 so that the maximum NO X purification rate can be obtained in the predetermined range, and the control unit U performs the idle operation. The fuel ratio is changed (f 1 : A / F = 15, f 2 : A / F = 16 in the embodiment in FIG. 2). Next, the control contents of the control unit U will be described with reference to a flowchart shown in FIG. In the following description, S indicates a step. First, in S1,
Engine speed Ne, intake air quantity Ce, real exhaust gas temperature T 1 is read in, in S2, the engine speed N
e, a target air-fuel ratio is determined based on the intake air amount Ce and the like, and it is determined whether or not the target air-fuel ratio is a stoichiometric air-fuel ratio (λ = 1). This is a problem that occurs when the vehicle is operated at the stoichiometric air-fuel ratio. Therefore, when S2 is YES,
In order to perform this control, the process proceeds to S3. In S3, the actual exhaust gas temperature T 1
Is included in the above-described predetermined range K 0 to K 1 . This is performed in order to determine whether or not the decrease in torque does not cause a problem even if the air-fuel ratio is changed so as to obtain a high (substantially maximum) NO X purification rate under the exhaust gas temperature T 1. Will be Therefore, when S3 is NO, the target air-fuel ratio is set to the stoichiometric air-fuel ratio in S4 while the target air-fuel ratio is set to the stoichiometric air-fuel ratio in S4.
When, as a torque reduction is not a problem, the air-fuel ratio Li from the target air-fuel ratio - in emissions (Fig. 2, f 1: A / F = 1
5, f 2 : A / F = 16, etc.). As a result, even when the exhaust gas temperature is low, such as when the engine is half warmed up, a high NO X purification rate can be obtained under the actual exhaust gas temperature T 1 with almost no problem of torque reduction. You can do it. On the other hand, if the answer in S2 is NO, it is determined that the control is not the subject of this control, and the program proceeds to S6, in which the engine coolant temperature WT is read.
The air-fuel ratio A / F 0 at the lean combustion limit L / L at T is calculated based on FIG. Subsequently, in S8, the air-fuel ratio A / F 1 which can obtain the maximum NO X purification rate under the exhaust gas temperature T 1 of the real is calculated based on Table 1.
The contents of this Table 1, as T 1 is low, the air-fuel ratio A / F 1 Galli - has to be a down trend. [Table 1] Next, in S9, the A / F 1 of S8 becomes S
7 is smaller (rich) than A / F 0 . This is performed in order to obtain the maximum NO X purification rate, but as a prerequisite, to ensure that combustion is possible. Therefore, S9 is YES
When, in S10, the maximum target air-fuel ratio is set to A / F 1 under the exhaust gas temperature T 1 of the real NO X
While purification rate is obtained, S9 is negative (NO), to ensure combustion assumption, in S11, the target air-fuel ratio is set to A / F 0 of the S7. As described above, according to the present invention, even when the exhaust gas temperature is low, such as when the engine is half-warmed, the N
It is possible to accurately prevent the Ox purification rate from decreasing.
【図面の簡単な説明】
【図１】実施例を示す全体系統図。
【図２】貴金属系ＮＯX 触媒に関し、触媒入口排気ガス
温度と空燃比とがＮＯX 浄化率に及ぼす影響、及び実施
例の概念を説明する図。
【図３】実施例に係る制御例を示す図。
【図４】希薄燃焼限界とエンジン冷却水温との関係を示
す特性線図。
【図５】目標空燃比の運転領域を示す図。
【符号の説明】
１ エンジン
６ 排気通路
７ エアフロメ−タ
９ 燃料噴射弁
１０ ＮＯX 触媒
１２ センサ
１３ センサ
１４ センサ
Ｕ 制御ユニットBRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram showing an embodiment. FIG. 2 is a view for explaining the effect of the catalyst inlet exhaust gas temperature and the air-fuel ratio on the NO X purification rate and the concept of the embodiment regarding a noble metal NO X catalyst. FIG. 3 is a diagram showing a control example according to the embodiment. FIG. 4 is a characteristic diagram showing a relationship between a lean burn limit and an engine coolant temperature. FIG. 5 is a diagram showing an operation range of a target air-fuel ratio. [Description of symbols] 1 Engine 6 exhaust passage 7 Eafurome - motor 9 fuel injection valve 10 NO X catalyst 12 sensor 13 sensor 14 sensor U control unit
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ Ｆ０２Ｄ 45/00 ３１２ Ｆ０２Ｄ 45/00 ３１２Ｒ (72)発明者 上岡 敏嗣 広島県安芸郡府中町新地３番１号 マツ ダ株式会社内 (56)参考文献 特開 平５−52135（ＪＰ，Ａ) 特開 昭60−35149（ＪＰ，Ａ) 特開 平４−58028（ＪＰ，Ａ) 特開 昭63−100919（ＪＰ，Ａ) 特開 平４−50441（ＪＰ，Ａ) 特開 平１−135541（ＪＰ，Ａ) 特開 平６−264728（ＪＰ，Ａ) 特開 平５−263631（ＪＰ，Ａ) 特開 平６−117232（ＪＰ，Ａ) 特開 平６−129236（ＪＰ，Ａ) 実開 昭59−150966（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.7，ＤＢ名) F02D 41/00 - 45/00 F01N 3/00 - 3/38 B01D 53/34,53/36 ────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. 7 Identification code FI F02D 45/00 312 F02D 45/00 312R (72) Inventor Toshishi Kamioka 3-1, Fuchu-cho, Shinchu, Aki-gun, Hiroshima Mazda (56) References JP-A-5-52135 (JP, A) JP-A-60-35149 (JP, A) JP-A-4-58028 (JP, A) JP-A-63-100919 (JP, A) JP-A-4-50441 (JP, A) JP-A-1-135541 (JP, A) JP-A-6-264728 (JP, A) JP-A-5-263363 (JP, A) JP-A-6-117232 (JP, A) JP-A-6-129236 (JP, A) JP-A-59-150966 (JP, U) (58) Fields investigated (Int. Cl. 7 , DB name) F02D 41/00-45 / 00 F01N 3/00-3/38 B01D 53 / 34,53 / 36
Claims (1)
の排気系に備えられ、排気ガス温度が低くなるほど最大
ＮＯｘ浄化率を実現するための空燃比がリーンになる特
性を有する貴金属系ＮＯｘ触媒と、 空燃比を変更する空燃比変更手段と、 前記ＮＯｘ触媒上流側の排気ガス温度を検出する温度検
出手段と、 目標空燃比を検出する目標空燃比検出手段と、 前記目標空燃比検出手段からの信号に基づき、理論空燃
比の運転領域に属すると判断したときであって、前記温
度検出手段からの信号に基づき、排気ガス温度が、理論
空燃比において最大ＮＯｘ浄化率を実現するための温度
から該温度よりも低い所定温度までの所定の温度範囲に
あると判断したとき、前記空燃比変更手段を制御して、
空燃比を理論空燃比よりも所定値リ−ン側へ変更する制
御手段と、 を備える、 ことを特徴とするエンジンの排気浄化装置。(57) [Claims 1] It is provided in an exhaust system of an engine having an operating range of a stoichiometric air-fuel ratio, and the maximum is as the exhaust gas temperature is lower.
The air-fuel ratio for achieving the NOx purification rate becomes lean.
A noble metal-based NOx catalyst having properties, air-fuel ratio changing means for changing the air-fuel ratio, temperature detecting means for detecting the exhaust gas temperature upstream of the NOx catalyst, target air-fuel ratio detecting means for detecting a target air-fuel ratio, When it is determined based on the signal from the target air-fuel ratio detection means that the exhaust gas temperature belongs to the operating range of the stoichiometric air-fuel ratio, and based on the signal from the temperature detection means, the exhaust gas temperature becomes
Temperature for achieving maximum NOx purification rate at air-fuel ratio
When it is determined that the temperature is within a predetermined temperature range from a predetermined temperature lower than the temperature, by controlling the air-fuel ratio changing means,
Control means for changing the air-fuel ratio to a predetermined value lean side from the stoichiometric air-fuel ratio.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09658493A JP3378044B2 (en) | 1993-03-31 | 1993-03-31 | Engine exhaust purification device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09658493A JP3378044B2 (en) | 1993-03-31 | 1993-03-31 | Engine exhaust purification device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06288273A JPH06288273A (en) | 1994-10-11 |
| JP3378044B2 true JP3378044B2 (en) | 2003-02-17 |
Family
ID=14168993
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP09658493A Expired - Fee Related JP3378044B2 (en) | 1993-03-31 | 1993-03-31 | Engine exhaust purification device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3378044B2 (en) |
-
1993
- 1993-03-31 JP JP09658493A patent/JP3378044B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06288273A (en) | 1994-10-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2712758B2 (en) | Exhaust gas purification device for internal combustion engine | |
| JP2586218B2 (en) | Control device for internal combustion engine | |
| JP3361252B2 (en) | Exhaust gas purification device for internal combustion engine | |
| JPH084522A (en) | Device and method for exhaust emission control of internal combustion engine | |
| JP3272465B2 (en) | Engine exhaust gas purification device | |
| JP2982440B2 (en) | Exhaust gas purification device for internal combustion engine | |
| JP3378044B2 (en) | Engine exhaust purification device | |
| JP2576487B2 (en) | Fuel supply control device for internal combustion engine | |
| JPH0435606B2 (en) | ||
| JPH06264787A (en) | Air-fuel ratio control device of internal combustion engine | |
| JP2884798B2 (en) | Exhaust gas purification device for internal combustion engine | |
| JP2003027987A (en) | Control system for internal combustion engine | |
| JP3258755B2 (en) | Engine exhaust purification device | |
| JP3764193B2 (en) | Exhaust purification device | |
| JP2910034B2 (en) | Air-fuel ratio control device for internal combustion engine | |
| JPS6254976B2 (en) | ||
| JPH0693840A (en) | Exhaust emission control device for internal combustion engine | |
| JP3401955B2 (en) | Exhaust gas purification device for internal combustion engine | |
| JP2917431B2 (en) | Exhaust gas purification device for internal combustion engine | |
| JPS59131741A (en) | Air-fuel ratio controlling method for internal- combustion engine | |
| JPS62178740A (en) | Exhaust gas purifying device for multicylinder engine | |
| JPH0518235A (en) | Secondary air control device for internal combustion engine | |
| JPH0636266Y2 (en) | Exhaust gas purification device for internal combustion engine | |
| JPS623159A (en) | Intake secondary air supply device for internal-combustion engine | |
| JPH0539750A (en) | Air-fuel ratio control device for carbureter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20071206 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20081206 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091206 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091206 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101206 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111206 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |