JPH0814031A - Judgement on reduction and absorption performance of nox reduction catalyst in internal combustion engine, and reduction of nox - Google Patents
Judgement on reduction and absorption performance of nox reduction catalyst in internal combustion engine, and reduction of noxInfo
- Publication number
- JPH0814031A JPH0814031A JP6142824A JP14282494A JPH0814031A JP H0814031 A JPH0814031 A JP H0814031A JP 6142824 A JP6142824 A JP 6142824A JP 14282494 A JP14282494 A JP 14282494A JP H0814031 A JPH0814031 A JP H0814031A
- Authority
- JP
- Japan
- Prior art keywords
- fuel ratio
- air
- nox
- reduction
- catalyst
- 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.)
- Pending
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
- F01N3/0828—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
- 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
- F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
- F01N2550/02—Catalytic activity of catalytic converters
-
- 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
- F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
- F01N2550/03—Monitoring or diagnosing the deterioration of exhaust systems of sorbing activity of adsorbents or absorbents
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Exhaust Gas After Treatment (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は理論空燃比より薄い空燃
比で運転を行う内燃機関におけるＮＯｘ還元触媒の還元
・吸着性能の判定とＮＯｘ低減方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a NOx reduction method and a method for determining the reduction / adsorption performance of a NOx reduction catalyst in an internal combustion engine operating at an air-fuel ratio lower than the theoretical air-fuel ratio.
【０００２】[0002]
【従来の技術】内燃機関の燃費向上のため定常運転時及
び通常の加速時などに空燃比を理論空燃比より薄い側、
即ちリーン側に制御する内燃機関（以下、リーンバーン
エンジンという）においては、従来、たとえば特開平5
−261287 号公報に記載されているように、触媒の浄化
性能を劣化させないように、設定空燃比を希薄限界空燃
比（以下、リーンリミットという）近くに設定し、この
空燃比と理論空燃比との間を交互に設定している。そし
て、ＮＯｘが多く発生する空燃比（Ａ／Ｆ＝１８〜２
０）では、運転しないようにしている。このため、排ガ
スの浄化性能を優先させて、燃費と運転性を犠牲にして
いる面がある。2. Description of the Related Art In order to improve the fuel efficiency of an internal combustion engine, the air-fuel ratio is lower than the theoretical air-fuel ratio during steady operation and normal acceleration.
That is, in an internal combustion engine that is controlled to the lean side (hereinafter referred to as a lean burn engine), there is a conventional method, for example, Japanese Patent Laid-Open No.
As described in the -261287 publication, the set air-fuel ratio is set near the lean limit air-fuel ratio (hereinafter referred to as lean limit) so as not to deteriorate the purification performance of the catalyst, and the air-fuel ratio and the theoretical air-fuel ratio Are set alternately. Then, the air-fuel ratio (A / F = 18 to 2) in which a large amount of NOx is generated
In 0), I try not to drive. For this reason, the purification performance of exhaust gas is prioritized to sacrifice fuel efficiency and drivability.
【０００３】しかし、燃費と運転性向上のためには、Ｎ
Ｏｘが発生する空燃比での運転が不可欠となる。However, in order to improve fuel economy and drivability, N
It is essential to operate at the air-fuel ratio that produces Ox.
【０００４】[0004]
【発明が解決しようとする課題】上記従来技術では、多
孔質の担体にＲｈ，Ｐｔを担持する三元触媒にＢａ，Ｌ
ａ等の金属を担持してＮＯｘを還元する触媒であるＮＯ
ｘ還元触媒の性能を有効に使用していない。このＮＯｘ
還元触媒はリーン状態が継続し、その時間が長くなって
も、基本的にＮＯｘの還元性能は劣化しない。しかし、
リーン状態でＮＯｘを吸着し、理論空燃比及び理論空燃
比より濃い（リッチ状態）空燃比域でＮＯｘを還元する
触媒では、リーン状態の時間が長くなると吸着性能が悪
化する。更に、ＮＯｘが多く発生する空燃比（Ａ／Ｆ＝
１８〜２０）では、短時間でＮＯｘの吸着性能が悪化す
る。即ち、ＮＯｘ還元触媒のＮＯxの吸着性能はＮＯx発
生量に依存する。In the above-mentioned conventional technique, Ba, L is used as a three-way catalyst in which Rh and Pt are supported on a porous carrier.
NO, which is a catalyst that carries a metal such as a to reduce NOx
The performance of x reduction catalyst is not used effectively. This NOx
Even if the reduction catalyst continues to be in a lean state and its time becomes long, basically, the NOx reduction performance does not deteriorate. But,
In the catalyst that adsorbs NOx in the lean state and reduces NOx in the stoichiometric air-fuel ratio and in the air-fuel ratio region that is richer than the stoichiometric air-fuel ratio (rich state), the adsorption performance deteriorates when the lean state becomes long. Furthermore, the air-fuel ratio (A / F =
18-20), the NOx adsorption performance deteriorates in a short time. That is, the NOx adsorption performance of the NOx reduction catalyst depends on the NOx generation amount.
【０００５】一方、理論空燃比及び理論空燃比より濃い
（リッチ状態）空燃比域では、リーン状態で吸着された
ＮＯｘはＣＯ，Ｈ2 ，ＨＣなどの還元ガスと反応し、Ｎ
2 に還元される。即ち、ＮＯｘ還元触媒のリーン状態で
吸着したＮＯｘの還元性能はＣＯ，Ｈ2 ，ＨＣなどの量
に依存する。On the other hand, in the stoichiometric air-fuel ratio and the air-fuel ratio region richer than the stoichiometric air-fuel ratio (rich state), the NOx adsorbed in the lean state reacts with the reducing gas such as CO, H 2 and HC, and N
Reduced to 2 . That is, the reducing performance of NOx adsorbed in the lean state of the NOx reducing catalyst depends on the amounts of CO, H 2 , HC and the like.
【０００６】本発明の目的は、ＮＯｘ還元触媒における
リーン状態の還元・吸着性能及びリッチ状態の還元性能
を十二分に引き出すＮＯｘ還元触媒の還元・吸着性能の
判定とこれに伴うＮＯｘ低減方法を提供するものであ
る。An object of the present invention is to determine the reduction / adsorption performance of a NOx reduction catalyst that fully brings out the lean reduction / adsorption performance and the rich reduction performance of the NOx reduction catalyst, and a NOx reduction method associated therewith. It is provided.
【０００７】[0007]
【課題を解決するための手段】上記目的を達成するた
め、本発明では、エンジンの空燃比を、空燃比とその空
燃比状態に留まる時間との積の総和に関する因子でＮＯ
ｘ還元触媒の還元・吸着性能の判定とエンジンの空燃比
を制御する構成とした。In order to achieve the above object, in the present invention, the engine air-fuel ratio is a factor related to the sum of the products of the air-fuel ratio and the time spent in the air-fuel ratio state.
x The configuration is such that the reduction / adsorption performance of the reduction catalyst is determined and the air-fuel ratio of the engine is controlled.
【０００８】[0008]
【作用】リーン状態でＮＯｘを吸着する触媒を有するＮ
Ｏｘ還元触媒のＮＯｘの吸着性能はＮＯｘ発生量に依存
するので、ＮＯｘが多く発生する空燃比（Ａ／Ｆ＝１８
〜２０）では、短時間で理論空燃比及び理論空燃比より
濃い（リッチ状態）空燃比域に切換える。ＮＯｘの排出
量が少ない空燃比（Ａ／Ｆ＝２２以上）では、長い時
間、リーン状態を保持し、その後、理論空燃比及び理論
空燃比より濃い（リッチ状態）空燃比域に切換える。[Function] N having a catalyst that adsorbs NOx in a lean state
Since the NOx adsorption performance of the Ox reduction catalyst depends on the NOx generation amount, the air-fuel ratio (A / F = 18) at which a large amount of NOx is generated.
(20), the stoichiometric air-fuel ratio and the air-fuel ratio region richer than the stoichiometric air-fuel ratio (rich state) are switched in a short time. At the air-fuel ratio (A / F = 22 or more) where the NOx emission amount is small, the lean state is maintained for a long time, and then the stoichiometric air-fuel ratio and the air-fuel ratio region richer than the theoretical air-fuel ratio (rich state) are switched.
【０００９】一方、理論空燃比及び理論空燃比より濃い
（リッチ状態）空燃比域では、リーン状態で吸着したＮ
ＯｘはＣＯ，Ｈ2 ，ＨＣなどの還元ガスと反応し、Ｎ2
に還元されるので、理論空燃比では、理論空燃比より濃
い（リッチ状態）空燃比に比べて、ＣＯ，Ｈ2 ，ＨＣが
少ないので長い時間、理論空燃比状態を保持する。理論
空燃比より濃い（リッチ状態）空燃比域では、ＣＯ，Ｈ
2 ，ＨＣが多いので、短い時間でＮＯｘの還元を行うこ
とができる。その後、リーン状態の条件であれば、リー
ン状態に移行する。On the other hand, in the stoichiometric air-fuel ratio and the air-fuel ratio region richer than the stoichiometric air-fuel ratio (rich state), N adsorbed in the lean state is adsorbed.
Ox reacts with a reducing gas such as CO, H 2 and HC to produce N 2
Therefore, the stoichiometric air-fuel ratio retains the stoichiometric air-fuel ratio state for a long time because the amount of CO, H 2 and HC is smaller than the stoichiometric air-fuel ratio (rich state). In the air-fuel ratio range that is richer than the theoretical air-fuel ratio (rich state), CO, H
2 Since there is a large amount of HC, it is possible to reduce NOx in a short time. After that, if the condition is the lean state, the state shifts to the lean state.
【００１０】[0010]
【実施例】以下、本発明による内燃機関におけるＮＯｘ
還元触媒の還元・吸着性能の判定とＮＯｘ低減方法につ
いて、図示の実施例により詳細に説明する。EXAMPLES NOx in an internal combustion engine according to the present invention will be described below.
The determination of the reduction / adsorption performance of the reduction catalyst and the NOx reduction method will be described in detail with reference to the illustrated embodiment.
【００１１】図１は本発明を実施するエンジン制御シス
テムにおける制御装置の入出力構成を示す一例である。
図１において、マイクロプロセッサ（ＭＰＵ）５０，制
御プログラムと各種データを記憶する読取専用の記憶装
置（以下、ＲＯＭと略す）５２，読み書き記憶装置（以
下、ＲＡＭと略す）５４，入力ポート５６及び出力ポー
ト５８，気筒判別信号５９が入る割込回路６０，マルチ
プレクサ（ＭＰＸ）６１を介すＡ／Ｄ変換器６２とリザ
ルトレジスタ（ＲＲＥＧ）６３，基準信号６５が入るイ
ンプット・キャプチャ・レジスタ（ＩＣＲ）６６，アウ
トプット・コンペア・レジスタ（ＯＣＲ１〜ＯＣＲ７）
６７〜７３などで構成される。FIG. 1 is an example showing an input / output configuration of a control device in an engine control system embodying the present invention.
1, a microprocessor (MPU) 50, a read-only storage device (hereinafter abbreviated as ROM) 52 that stores a control program and various data, a read / write storage device (hereinafter abbreviated as RAM) 54, an input port 56, and an output. Port 58, interrupt circuit 60 into which cylinder discrimination signal 59 is input, A / D converter 62 and result register (RREG) 63 via multiplexer (MPX) 61, and input capture register (ICR) 66 into which reference signal 65 is input. , Output compare registers (OCR1 to OCR7)
67 to 73 and the like.
【００１２】アナログ入力としては、空気流量センサ７
４,バッテリ電圧７５,スロットルセンサ７６，Ｏ2 セン
サ７７，水温センサ７８などがある。入力ポート５６に
は、アイドルＳＷ７９，スタータＳＷ８０、出力ポート
５８には、フューエルポンプ８１などが接続される。ア
ウトプット・コンペア・レジスタ(ＯＣＲ１〜ＯＣＲ７)６
７〜７３には、インジェクタ１〜４，点火装置８６，エ
ヤバイパスバルブ８７，アウトプット・コンペア・レジ
スタ（ＯＣＲ７）７３のデューティ出力をアナログメー
タに表示する回路８８などが接続される。As an analog input, the air flow rate sensor 7
4, battery voltage 75, throttle sensor 76, O 2 sensor 77, water temperature sensor 78 and the like. An idle SW 79 and a starter SW 80 are connected to the input port 56, and a fuel pump 81 and the like are connected to the output port 58. Output compare register (OCR1 to OCR7) 6
7 to 73 are connected to injectors 1 to 4, an ignition device 86, an air bypass valve 87, a circuit 88 for displaying the duty output of the output compare register (OCR7) 73 on an analog meter, and the like.
【００１３】ＭＰＵ５０，ＲＯＭ５２，ＲＡＭ５４，入
力ポート５６及び出力ポート５８，割込回路６０，リザ
ルトレジスタ(ＲＲＥＧ)６３，インプット・キャプチャ
・レジスタ(ＩＣＲ)６６，アウトプット・コンペア・レ
ジスタ(ＯＣＲ１〜ＯＣＲ７)６７〜７３には、内部アド
レスバス，内部データバス８９が共通につながれてい
る。MPU 50, ROM 52, RAM 54, input port 56 and output port 58, interrupt circuit 60, result register (RREG) 63, input capture register (ICR) 66, output compare registers (OCR1 to OCR7) An internal address bus and an internal data bus 89 are commonly connected to 67 to 73.
【００１４】ＭＰＵ５０はＲＯＭ５２に予め格納された
プログラムに従って処理を開始する。制御プログラムと
各種データを記憶する読取専用の記憶装置ＲＯＭ５２
に、燃料制御用プログラムや点火時期制御用プログラム
などがある。燃料制御用プログラムでは、アナログ入力
の空気流量センサ７４を取込み、吸入空気流量Ｑａを演
算する。そして、エンジン回転数Ｎｅは基準信号６５が
入るインプット・キャプチャ・レジスタ（ＩＣＲ）６６
の周期を測定することにより求められる。The MPU 50 starts processing according to a program stored in the ROM 52 in advance. Read-only storage device ROM 52 for storing control programs and various data
There is a fuel control program and an ignition timing control program. In the fuel control program, the analog input air flow rate sensor 74 is taken in and the intake air flow rate Qa is calculated. The engine speed Ne is the input capture register (ICR) 66 into which the reference signal 65 is input.
It is obtained by measuring the period of.
【００１５】一方、燃料噴射時間Ｔｉは次式で計算され
る。On the other hand, the fuel injection time Ti is calculated by the following equation.
【００１６】 Ｔｉ＝α・Ｔｐ・Ｋ＋Ｔｓ …（１） ここで、α ：Ｏ2 フィードバック補正係数 Ｔｐ：基本燃料噴射時間 Ｋ ：補正係数の和 Ｔｓ：無効噴射時間 シリンダ内への吸入空気量となる基本燃料噴射時間Ｔｐ
は次式のようになる。Ti = α · Tp · K + Ts (1) where α: O 2 feedback correction coefficient Tp: basic fuel injection time K: sum of correction coefficients Ts: invalid injection time, which is the intake air amount into the cylinder Basic fuel injection time Tp
Is as follows.
【００１７】 Ｔｐ＝ｋ・Ｑａ／Ｎｅ …（２） ここで、ｋ ：インジェクタ係数 Ｑａ：吸入空気流量 Ｎｅ：エンジン回転数 基本燃料噴射時間Ｔｐは一回転当たりの吸入空気量とな
る。補正係数の和Ｋは次式のようになる。Tp = k · Qa / Ne (2) where k: injector coefficient Qa: intake air flow rate Ne: engine speed The basic fuel injection time Tp is the intake air amount per rotation. The sum K of correction coefficients is given by the following equation.
【００１８】 Ｋ＝１＋Ｋｗ・Ｋａ・Ｋｍｒ・Ｋｓ・Ｋｄｅｃ …（３） ここで、Ｋｗ ：水温補正係数 Ｋａ ：アフタアイドル補正係数 Ｋｍｒ ：混合比補正係数 Ｋｓ ：アフタスタート補正係数 Ｋｄｅｃ：減速補正係数 空燃比Ａ／Ｆは（１）式から次式のようになる。K = 1 + Kw · Ka · Kmr · Ks · Kdec (3) where Kw: Water temperature correction coefficient Ka: After idle correction coefficient Kmr: Mixing ratio correction coefficient Ks: After start correction coefficient Kdec: Deceleration correction coefficient The fuel ratio A / F is given by the following equation from the equation (1).
【００１９】 Ａ／Ｆ＝Ｔｐ／(Ｔｉ−Ｔｓ） …（４） （４）式はシリンダ内への吸入空気量（基本燃料噴射時
間Ｔｐ）と実燃料噴射時間（Ｔｉ−Ｔｓ）の比を表して
いる。（４）式から空燃比Ａ／Ｆが推定できる。A / F = Tp / (Ti-Ts) (4) Equation (4) is a ratio of the intake air amount into the cylinder (basic fuel injection time Tp) to the actual fuel injection time (Ti-Ts). It represents. The air-fuel ratio A / F can be estimated from the equation (4).
【００２０】（４）式で計算された結果をアウトプット
・コンペア・レジスタ（ＯＣＲ７）７３のデューティ出
力結果をアナログメータに表示する回路８８に出力す
る。回路８８ではバッテリ電圧依存性を抑えるためツェ
ナーダイオードＺＤ９０をいれている。また、アナログ
メータ９２の表示としては、一旦使用電圧にメータセッ
ト調整抵抗Ｒｓを用いて表示を調整すれば再調整は不要
となる。抵抗Ｒ1 はツェナーダイオードＺＤ９０のツェ
ナー電流制限抵抗としていれている。アナログメータ９
２は電流値の小さなメータが抵抗の発熱の点で有利であ
る。The result calculated by the equation (4) is output to the circuit 88 for displaying the duty output result of the output compare register (OCR7) 73 on the analog meter. In the circuit 88, a Zener diode ZD90 is added to suppress the battery voltage dependency. Further, regarding the display of the analog meter 92, once the display is adjusted by using the meter set adjusting resistor Rs for the working voltage, readjustment becomes unnecessary. The resistor R 1 is used as the Zener current limiting resistor of the Zener diode ZD90. Analog meter 9
No. 2 is advantageous in that a meter with a small current value generates heat from the resistance.
【００２１】実空燃比Ａ／Ｆは（４）式からシリンダ内
への吸入空気量（基本燃料噴射時間Ｔｐ）と実燃料噴射
時間（Ｔｉ−Ｔｓ）の比で常に計算され、アナログメー
タ９２で読み取ることができる。The actual air-fuel ratio A / F is always calculated from the equation (4) by the ratio of the intake air amount into the cylinder (basic fuel injection time Tp) and the actual fuel injection time (Ti-Ts), and the analog meter 92 Can be read.
【００２２】図２は良く知られているように空燃比（Ａ
／Ｆ）に対するＮＯｘ，ＣＯの発生量を表した線図であ
る。FIG. 2 shows that the air-fuel ratio (A
It is a diagram showing the generation amount of NOx and CO with respect to / F).
【００２３】図３は安定した状態におけるＮＯｘ還元触
媒の空燃比に対するＮＯｘ浄化率を示す。理論空燃比よ
りリッチ側は三元触媒の作用により、ＮＯｘ浄化率はほ
ぼ１００％となる。空燃比が理論空燃比よりリーン側に
移行するにつれて、浄化率は減少し、空燃比が２２近辺
で浄化率は０となる。しかし、この触媒はＮＯｘの吸着
性能を持っているため、理論空燃比よりもリッチ状態か
らリーン状態に戻した場合、図４に示したように初期に
はＮＯｘの浄化率は非常に高い値を示している。この浄
化率は時間の経過と共に減少し、約２〜４分程度で浄化
性能を失う。この性質は再現性があり、再びリッチにし
てリーンに戻した場合に同じ性能を発揮する。FIG. 3 shows the NOx purification rate with respect to the air-fuel ratio of the NOx reduction catalyst in a stable state. On the rich side of the theoretical air-fuel ratio, the NOx purification rate becomes almost 100% due to the action of the three-way catalyst. As the air-fuel ratio shifts to the lean side from the stoichiometric air-fuel ratio, the purification rate decreases, and the purification rate becomes 0 near the air-fuel ratio of 22. However, since this catalyst has NOx adsorption performance, when the rich state is returned to the lean state with respect to the stoichiometric air-fuel ratio, the NOx purification rate becomes very high in the initial stage as shown in FIG. Shows. This purification rate decreases with the passage of time, and the purification performance is lost in about 2 to 4 minutes. This property is reproducible and gives the same performance when reriched and leaned back.
【００２４】図５はリーン状態で吸着したＮＯｘの理論
空燃比よりもリッチ状態での還元性能を示す。還元性能
はＣＯ，Ｈ2 ，ＨＣに依存するので、図のように空燃比
によって変化する。FIG. 5 shows the reducing performance of NOx adsorbed in the lean state in a richer state than the stoichiometric air-fuel ratio. Since the reducing performance depends on CO, H 2 , and HC, it changes depending on the air-fuel ratio as shown in the figure.
【００２５】図６はＮＯｘの時間当たりの吸着係数Ｋ１
を示す。理論空燃比よりリッチ側では、三元触媒の作用
により、ＮＯｘ浄化率はほぼ１００％なので、吸着係数
Ｋ１を１.０ にする。理論空燃比よりリーン側では、図
２によるＮＯｘ発生量が空燃比１６付近で最大になり、
リーン側に移行するにつれて、発生量は減少する。吸着
能力はＮＯｘ発生量に反比例するので、吸着係数Ｋ１は
リーン側に移行するにつれて、減少する係数とする。つ
まり、リーン側に移行するにつれて、吸着する時間が長
くなっても触媒の劣化がないことを意味する。FIG. 6 shows the adsorption coefficient K1 of NOx per unit time.
Indicates. On the rich side of the theoretical air-fuel ratio, the NOx purification rate is almost 100% due to the action of the three-way catalyst, so the adsorption coefficient K1 is set to 1.0. On the lean side from the theoretical air-fuel ratio, the NOx generation amount according to FIG. 2 becomes the maximum near the air-fuel ratio 16,
The amount decreases as it moves to the lean side. Since the adsorption capacity is inversely proportional to the NOx generation amount, the adsorption coefficient K1 is a coefficient that decreases as it shifts to the lean side. That is, it means that the catalyst does not deteriorate even if the adsorption time becomes longer as it shifts to the lean side.
【００２６】図７はＮＯｘの時間当たりの還元係数Ｋｒ
を示す。リーン状態で吸着されたＮＯｘはＣＯ，Ｈ2 ，
ＨＣなどで還元されるので、理論空燃比よりもリッチ状
態で次第に多くなるＣＯに関係して、還元係数Ｋｒは空
燃比１２よりリッチで1.0にする。そして、空燃比１２
より理論空燃比までは減少する係数とする。つまり、リ
ーン状態で吸着したＮＯｘの還元時間は理論空燃比で最
も長くなる。FIG. 7 shows the reduction coefficient Kr of NOx per unit time.
Indicates. NOx adsorbed in the lean state is CO, H 2 ,
Since it is reduced by HC or the like, the reduction coefficient Kr is set to 1.0 richer than the air-fuel ratio 12 in relation to CO that gradually increases in a richer state than the stoichiometric air-fuel ratio. And the air-fuel ratio is 12
It is a coefficient that decreases to the theoretical air-fuel ratio. That is, the reduction time of NOx adsorbed in the lean state becomes the longest at the theoretical air-fuel ratio.
【００２７】図８，図９は本発明に係わる処理を表した
フローチャートを示す。この処理は一定時間毎に、例え
ば、１０ｍｓ周期で実行される。まず、ステップ１００
でエンジン回転数Ｎｅを読込む。ステップ１０２では、
空気流量センサを読込み、吸入空気流量Ｑａを演算す
る。次に、ステップ１０４でＮｅとＱａより基本燃料噴
射時間Ｔｐを算出する。ステップ１０６で燃料噴射時間
Ｔｉを算出する。ステップ１０８でＴｐと実燃料噴射時
間（Ｔｉ−Ｔｓ）から現在の実空燃比Ａ／Ｆを推定す
る。8 and 9 are flow charts showing the processing according to the present invention. This process is executed at regular intervals, for example, in a cycle of 10 ms. First, step 100
Read the engine speed Ne. In step 102,
The air flow rate sensor is read and the intake air flow rate Qa is calculated. Next, at step 104, the basic fuel injection time Tp is calculated from Ne and Qa. In step 106, the fuel injection time Ti is calculated. At step 108, the current actual air-fuel ratio A / F is estimated from Tp and the actual fuel injection time (Ti-Ts).
【００２８】ステップ１１０で理論空燃比または理論空
燃比よりリッチかどうか判定する。理論空燃比または理
論空燃比よりリッチであれば、ステップ１１２に進む。
ステップ１１２では、ＮＯｘの時間当たりの還元係数Ｋ
ｒの計算を行う。ステップ１１４はＫｒの積算ΣＫｒの
計算を行う。ステップ１１６では、ΣＫｒが所定値以上
かどうか判定する。所定値以上であれば、ステップ１１
８で、リーン状態で吸着されたＮＯｘはＣＯ，Ｈ2 ，Ｈ
Ｃなどで還元されたので、リーン領域への切換えをＯＫ
とする。これにより、ステップ１２０でΣＫｒを０にす
る。ステップ１２２では、次の目標空燃比の設定を行
う。ステップ１１６でΣＫｒが所定値より小さい場合は
リーン状態で吸着されたＮＯｘはＣＯ，Ｈ2 ，ＨＣなど
で還元されないので、次のステップへ向かう。In step 110, it is determined whether the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio is richer. If the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio is richer, the routine proceeds to step 112.
In step 112, the reduction coefficient K of NOx per hour
Calculate r. In step 114, the integration ΣKr of Kr is calculated. In step 116, it is determined whether ΣKr is a predetermined value or more. If it is not less than the predetermined value, step 11
NOx adsorbed in the lean state at 8 is CO, H 2 , H
Since it was reduced by C etc., it is OK to switch to the lean region.
And As a result, ΣKr is set to 0 in step 120. In step 122, the next target air-fuel ratio is set. If ΣKr is smaller than the predetermined value in step 116, NOx adsorbed in the lean state is not reduced by CO, H 2 , HC, etc., and therefore the process proceeds to the next step.
【００２９】一方、ステップ１１０でリーン領域と判定
されたら、ステップ１２４へ進む。ステップ１２４で
は、ＮＯｘの時間当たりの吸着係数Ｋ１の計算を行う。
ステップ１２６はＫ１の積算ΣＫ１の計算を行う。ステ
ップ１２８では、ΣＫ１が所定値以上かどうか判定す
る。所定値以上であれば、ステップ１３０で、ＮＯｘの
吸着能力が限界と考え、理論空燃比または理論空燃比よ
りリッチ領域への切換えを行う。これにより、ステップ
１３２でΣＫ１を０にする。ステップ１２８でΣＫ１が
所定値より小さい場合はＮＯｘの吸着能力には、まだ、
余裕があるのでステップ１２２に進む。On the other hand, if it is determined in step 110 that the area is lean, the process proceeds to step 124. In step 124, the adsorption coefficient K1 of NOx per hour is calculated.
In step 126, the integration ΣK1 of K1 is calculated. In step 128, it is determined whether ΣK1 is a predetermined value or more. If it is not less than the predetermined value, in step 130, the NOx adsorption capacity is considered to be the limit, and the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio is switched to the rich region. As a result, ΣK1 is set to 0 in step 132. If ΣK1 is smaller than the predetermined value in step 128, the NOx adsorption capacity still has
Since there is room, it proceeds to step 122.
【００３０】[0030]
【発明の効果】以上説明した如く、上記処理により、三
元触媒にＢａ，Ｌａ等の金属を担持したＮＯｘを還元す
る触媒のリーン状態の還元・吸着性能及びリッチ状態の
還元性能を十二分に引き出すことができ、ＮＯｘ排出量
を大幅に改善することができる。また、ＮＯｘの吸着性
能を常に判定しているので、ＮＯｘが発生する空燃比で
の運転が可能となる。As described above, by the above treatment, the lean reduction / adsorption performance and the rich reduction performance of the catalyst for reducing NOx in which a metal such as Ba or La is carried on the three-way catalyst are more than sufficient. Therefore, the NOx emission amount can be greatly improved. In addition, since the NOx adsorption performance is constantly determined, it is possible to operate at the air-fuel ratio at which NOx is generated.
【図１】本発明を実施するエンジン制御システムにおけ
る制御装置の入出力構成を示す図である。FIG. 1 is a diagram showing an input / output configuration of a control device in an engine control system embodying the present invention.
【図２】空燃比（Ａ／Ｆ）に対するＮＯｘ，ＣＯの発生
量を表した線図である。FIG. 2 is a diagram showing the generation amounts of NOx and CO with respect to the air-fuel ratio (A / F).
【図３】ＮＯｘ還元触媒の空燃比に対するＮＯｘ浄化率
を示す図である。FIG. 3 is a diagram showing a NOx purification rate with respect to an air-fuel ratio of a NOx reduction catalyst.
【図４】ＮＯｘ浄化率と空燃比（Ａ／Ｆ）の関係を示す
図である。FIG. 4 is a diagram showing a relationship between a NOx purification rate and an air-fuel ratio (A / F).
【図５】リーン状態で吸着したＮＯｘの理論空燃比より
もリッチ状態での還元性能を示す図である。FIG. 5 is a graph showing reduction performance of NOx adsorbed in a lean state in a richer state than the stoichiometric air-fuel ratio.
【図６】ＮＯｘの時間当たりの吸着係数Ｋ１を示す図で
ある。FIG. 6 is a diagram showing an adsorption coefficient K1 of NOx per unit time.
【図７】ＮＯｘの時間当たりの還元係数Ｋｒを示す図で
ある。FIG. 7 is a diagram showing a reduction coefficient Kr of NOx per unit time.
【図８】本発明に係わる処理を表したフローチャートで
ある。FIG. 8 is a flowchart showing a process according to the present invention.
【図９】同じく処理を表したフローチャートである。FIG. 9 is a flowchart showing the same processing.
７３…アウトプット・コンペア・レジスタ（ＯＣＲ
７）、８８…デューティ出力をアナログメータに表示す
る回路、１１８…ステップ１１８、１３０…ステップ１
３０。73 ... Output compare register (OCR
7), 88 ... Circuit for displaying duty output on analog meter, 118 ... Step 118, 130 ... Step 1
30.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｆ０２Ｄ 41/14 ３１０ Ｋ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display area F02D 41/14 310 K
Claims (4)
比に制御すると同時に、アルミナ担体にＲｈ，Ｐｔを担
持する三元触媒にＢａ，Ｌａ等の金属を担持したＮＯｘ
を還元する触媒を装着した内燃機関において、エンジン
の空燃比とその空燃比状態に留まる時間との積の総和に
関する因子によって、ＮＯｘ還元触媒の還元・吸着性能
の判定を行うことを特徴とする内燃機関におけるＮＯｘ
還元触媒の還元・吸着性能の判定とＮＯｘ低減方法。1. A NOx in which a metal such as Ba or La is supported on a three-way catalyst in which Rh or Pt is supported on an alumina carrier while controlling the air-fuel ratio to a side thinner than the theoretical air-fuel ratio during vehicle operation.
In an internal combustion engine equipped with a catalyst that reduces NOx, the reduction / adsorption performance of the NOx reduction catalyst is determined by a factor related to the sum of products of the air-fuel ratio of the engine and the time for which the engine stays in the air-fuel ratio state. NOx in the engine
Judgment of reduction / adsorption performance of reduction catalyst and NOx reduction method.
比に制御すると同時に、アルミナ担体にＲｈ，Ｐｔを担
持する三元触媒にＢａ，Ｌａ等の金属を担持したＮＯｘ
を還元する触媒を装着した内燃機関において、エンジン
の空燃比を、空燃比とその空燃比状態に留まる時間との
積の総和に関する因子によって制御することを特徴とす
る内燃機関におけるＮＯｘ還元触媒の還元・吸着性能の
判定とＮＯｘ低減方法。2. A NOx in which a metal such as Ba or La is supported on a three-way catalyst in which Rh and Pt are supported on an alumina carrier while controlling the air-fuel ratio to a side thinner than the theoretical air-fuel ratio during vehicle operation.
In an internal combustion engine equipped with a catalyst for reducing NOx, the reduction of the NOx reduction catalyst in the internal combustion engine is characterized by controlling the air-fuel ratio of the engine by a factor related to the sum of products of the air-fuel ratio and the time spent in the air-fuel ratio state. -Judging adsorption performance and NOx reduction method.
比に制御すると同時に、アルミナ担体にＲｈ，Ｐｔを担
持する三元触媒にＢａ，Ｌａ等の金属を担持したＮＯｘ
を還元する触媒を装着した内燃機関において、エンジン
の空燃比を推定する手段と，その空燃比状態に留まる時
間を計測する手段とを備え、エンジンの空燃比を、空燃
比とその空燃比状態に留まる時間との積の総和に関する
因子によって制御することを特徴とする内燃機関におけ
るＮＯｘ還元触媒の還元・吸着性能の判定とＮＯｘ低減
方法。3. A NOx in which a three-way catalyst in which Rh and Pt are loaded on an alumina carrier is loaded with a metal such as Ba or La while the air-fuel ratio is controlled to be thinner than the theoretical air-fuel ratio during vehicle operation.
In an internal combustion engine equipped with a catalyst for reducing CO, a means for estimating the air-fuel ratio of the engine and a means for measuring the time spent in the air-fuel ratio state are provided, and the air-fuel ratio of the engine is changed to the air-fuel ratio and its air-fuel ratio state. A method for determining reduction / adsorption performance of a NOx reduction catalyst in an internal combustion engine and a NOx reduction method, which is controlled by a factor relating to a sum of products with a staying time.
比に制御すると同時に、アルミナ担体にＲｈ,Ｐｔを担
持する三元触媒にＢａ,Ｌａ等の金属を担持したＮＯｘ
を還元する触媒を装着した内燃機関において、エンジン
の空燃比を推定する手段と，その空燃比状態に留まる時
間を計測する手段とを備え、エンジンの空燃比を、空燃
比とその空燃比状態に留まる時間との積の総和に関する
因子によって制御し、この制御空燃比は一方は理論空燃
比、または理論空燃比よりリッチであり、他方は理論空
燃比より薄い側の空燃比にすることを特徴とする内燃機
関におけるＮＯｘ還元触媒の還元・吸着性能の判定とＮ
Ｏｘ低減方法。4. A NOx in which a metal such as Ba or La is carried on a three-way catalyst carrying Rh, Pt on an alumina carrier while controlling the air-fuel ratio on the side thinner than the theoretical air-fuel ratio during vehicle operation.
In an internal combustion engine equipped with a catalyst for reducing CO, a means for estimating the air-fuel ratio of the engine and a means for measuring the time spent in the air-fuel ratio state are provided, and the air-fuel ratio of the engine is changed to the air-fuel ratio and its air-fuel ratio state. It is controlled by a factor related to the sum of the product of the staying time and this. Of NOx reduction catalyst and N
Ox reduction method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6142824A JPH0814031A (en) | 1994-06-24 | 1994-06-24 | Judgement on reduction and absorption performance of nox reduction catalyst in internal combustion engine, and reduction of nox |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6142824A JPH0814031A (en) | 1994-06-24 | 1994-06-24 | Judgement on reduction and absorption performance of nox reduction catalyst in internal combustion engine, and reduction of nox |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0814031A true JPH0814031A (en) | 1996-01-16 |
Family
ID=15324482
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6142824A Pending JPH0814031A (en) | 1994-06-24 | 1994-06-24 | Judgement on reduction and absorption performance of nox reduction catalyst in internal combustion engine, and reduction of nox |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0814031A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0903478A3 (en) * | 1997-09-19 | 1999-12-01 | Toyota Jidosha Kabushiki Kaisha | An exhaust gas purification device for an internal combustion engine |
| EP0903479A3 (en) * | 1997-09-19 | 1999-12-29 | Toyota Jidosha Kabushiki Kaisha | An exhaust gas purification device for an internal combustion engine |
| EP1209332A2 (en) * | 2000-11-22 | 2002-05-29 | Volkswagen Aktiengesellschaft | Method and apparatus for regenerating a NOx storage catalyst |
| KR100435767B1 (en) * | 2002-06-18 | 2004-06-10 | 현대자동차주식회사 | a fail detecting method for cold start emission reduction device of car |
| EP0904482B2 (en) † | 1996-06-10 | 2010-01-20 | Hitachi, Ltd. | Exhaust gas purification apparatus of an internal combustion engine and catalyst for purifying exhaust gas of an internal combustion engine |
-
1994
- 1994-06-24 JP JP6142824A patent/JPH0814031A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0904482B2 (en) † | 1996-06-10 | 2010-01-20 | Hitachi, Ltd. | Exhaust gas purification apparatus of an internal combustion engine and catalyst for purifying exhaust gas of an internal combustion engine |
| EP0903478A3 (en) * | 1997-09-19 | 1999-12-01 | Toyota Jidosha Kabushiki Kaisha | An exhaust gas purification device for an internal combustion engine |
| EP0903479A3 (en) * | 1997-09-19 | 1999-12-29 | Toyota Jidosha Kabushiki Kaisha | An exhaust gas purification device for an internal combustion engine |
| US6138453A (en) * | 1997-09-19 | 2000-10-31 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device for an internal combustion engine |
| US6263667B1 (en) | 1997-09-19 | 2001-07-24 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device for an internal combustion engine |
| EP1209332A2 (en) * | 2000-11-22 | 2002-05-29 | Volkswagen Aktiengesellschaft | Method and apparatus for regenerating a NOx storage catalyst |
| EP1209332A3 (en) * | 2000-11-22 | 2004-06-09 | Volkswagen Aktiengesellschaft | Method and apparatus for regenerating a NOx storage catalyst |
| KR100435767B1 (en) * | 2002-06-18 | 2004-06-10 | 현대자동차주식회사 | a fail detecting method for cold start emission reduction device of car |
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