JPH0697001B2 - Air-fuel ratio controller for internal combustion engine using alcohol fuel - Google Patents
Air-fuel ratio controller for internal combustion engine using alcohol fuelInfo
- Publication number
- JPH0697001B2 JPH0697001B2 JP27585587A JP27585587A JPH0697001B2 JP H0697001 B2 JPH0697001 B2 JP H0697001B2 JP 27585587 A JP27585587 A JP 27585587A JP 27585587 A JP27585587 A JP 27585587A JP H0697001 B2 JPH0697001 B2 JP H0697001B2
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- oxygen sensor
- fuel
- engine
- 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 - Lifetime
Links
- 239000000446 fuel Substances 0.000 title claims description 76
- 238000002485 combustion reaction Methods 0.000 title claims description 18
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 title claims description 6
- 239000001301 oxygen Substances 0.000 claims description 64
- 229910052760 oxygen Inorganic materials 0.000 claims description 64
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 63
- 238000013459 approach Methods 0.000 claims 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 31
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 15
- 229910052697 platinum Inorganic materials 0.000 description 15
- 239000003054 catalyst Substances 0.000 description 13
- 238000002347 injection Methods 0.000 description 10
- 239000007924 injection Substances 0.000 description 10
- 239000010410 layer Substances 0.000 description 9
- 239000000919 ceramic Substances 0.000 description 8
- 238000001514 detection method Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 6
- 239000011241 protective layer Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- 230000001133 acceleration Effects 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000010948 rhodium Substances 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 229910052596 spinel Inorganic materials 0.000 description 2
- 239000011029 spinel Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Description
【発明の詳細な説明】 〈産業上の利用分野〉 本発明は酸素センサを用いて空燃比をフィードバック制
御する空燃比制御装置に関し、特にアルコール燃料を使
用する内燃機関に好適な空燃比制御装置に関する。Description: TECHNICAL FIELD The present invention relates to an air-fuel ratio control device that feedback-controls an air-fuel ratio using an oxygen sensor, and particularly to an air-fuel ratio control device suitable for an internal combustion engine that uses alcohol fuel. .
〈従来の技術〉 電子制御燃料噴射式内燃機関において、噴射量Tiは次式
によって定められる。<Prior Art> In an electronically controlled fuel injection internal combustion engine, the injection amount Ti is determined by the following equation.
Ti＝Tp・COEF・α＋Ts ここで、Tpは基本燃料噴射量であってTp＝Ｋ・Q/Nで与
えられ、Ｋは定数、Ｑは機関吸入空気流量、Ｎは機関回
転数である。COEFは水温補正等の各種補正係数、αは後
述する空燃比フィードバック制御（以下λコントロール
とする）のための空燃比フィードバック補正係数、Tsは
電圧補正分である。Ti = Tp · COEF · α + Ts Here, Tp is the basic fuel injection amount and is given by Tp = K · Q / N, where K is a constant, Q is the engine intake air flow rate, and N is the engine speed. COEF is various correction factors such as water temperature correction, α is an air-fuel ratio feedback correction factor for air-fuel ratio feedback control (hereinafter referred to as λ control) described later, and Ts is a voltage correction amount.
λコントロールは、排気系に酸素センサを設けて実際の
空燃比を検出し、この空燃比が目標空燃比より濃い（リ
ッチ）か薄い（リーン）かをスライスレベルにより制御
するもので、このため、フィードバック補正係数αとい
うものを定めて、このαを変化させることにより目標空
燃比に保っている（実開昭60−116053号等参照）。The λ control is to provide an oxygen sensor in the exhaust system to detect the actual air-fuel ratio, and to control whether this air-fuel ratio is richer (rich) or thinner (lean) than the target air-fuel ratio by the slice level. A feedback correction coefficient α is set and is changed to maintain the target air-fuel ratio (see No. 60-116053, Shokai).
そして、従来この種の空燃比制御装置に使用される酸素
センサとしては、特開昭58−204365号公報等に示される
ものが一般的である。As an oxygen sensor conventionally used in this type of air-fuel ratio control device, the one disclosed in JP-A-58-204365 is generally used.
この酸素センサは酸化ジルコニウム（ZrO2）を主成分と
するセラミック管の内外表面に白金電極を設け、外表面
の白金電極上に白金触媒層，マグネシウムスピネル等の
保護層を順次積層して構成されており、セラミック管の
内側空洞に大気（基準気体）を導く一方、セラミック管
の外側を機関排気と接触させ、大気中の酸素濃度（略一
定）と排気中の酸素濃度との比に応じた電圧を両電極間
に発生させて排気中の酸素濃度を検出するものである。This oxygen sensor is constructed by providing a platinum electrode on the inner and outer surfaces of a ceramic tube containing zirconium oxide (ZrO 2 ) as a main component, and sequentially laminating a platinum catalyst layer and a protective layer such as magnesium spinel on the platinum electrode on the outer surface. The atmosphere (reference gas) is guided to the inner cavity of the ceramic tube, while the outside of the ceramic tube is brought into contact with the engine exhaust, depending on the ratio between the oxygen concentration in the atmosphere (approximately constant) and the oxygen concentration in the exhaust. A voltage is generated between both electrodes to detect the oxygen concentration in the exhaust gas.
ここで、酸素センサの白金触媒層では、一般化炭素COや
炭化水素HCと酸素O2とのCO＋1/2O2→CO2,HC＋O2→H2O＋
CO2なる酸化反応を促進し、理論空燃比よりリッチ混合
気で燃焼させたときには、その部分に残存するO2をCOは
HCと良好に反応させてO2濃度を略零としセラミック管内
外のO2濃度比を大きくして大きな電圧を発生させる一
方、理論空燃比よりリーン混合気で燃焼させたときに
は、排気中に多量のO2と少量のCO,CHが存在するのでCO,
HCとO2とが反応してもO2が余りセラミック管外内のO2濃
度比が小さく電圧はほとんど発生しない。Here, in the platinum catalyst layer of the oxygen sensor, CO + 1 / 2O 2 → CO 2 , HC + O 2 → H 2 O + of generalized carbon CO or hydrocarbon HC and oxygen O 2
It promotes CO 2 becomes oxidation reaction, when burned in the rich mixture from the stoichiometric air-fuel ratio, the O 2 remaining in that portion CO is
It reacts well with HC to make the O 2 concentration almost zero and increase the O 2 concentration ratio inside and outside the ceramic tube to generate a large voltage, while when burning with a lean mixture than the stoichiometric air-fuel ratio, a large amount is present in the exhaust gas. O 2 and small amounts of CO and CH are present, so CO,
HC and O 2 and the O 2 concentration ratio is small voltage reacted ceramic in the extravascular much even O 2 is hardly generated.
〈発明が解決しようとする問題点〉 ところで、アルコール燃料、例えばメタノール燃料を使
用する内燃機関にあっては、排気中に未燃焼のメタノー
ルが存在する。そして、急加速や高速運転時の燃焼温度
が高い運転状態ではメタノールの分解（CH3OH→CO＋2
H2）が活発化して排気中にH2が多量に発生する。<Problems to be Solved by the Invention> By the way, in an internal combustion engine using an alcohol fuel, for example, a methanol fuel, unburned methanol exists in the exhaust gas. Then, during sudden acceleration or high-speed operation where combustion temperature is high, decomposition of methanol (CH 3 OH → CO + 2
H 2 ) is activated and a large amount of H 2 is generated in the exhaust gas.
このH2は白金触媒層において、H2＋1/2O2→H2Oの反応に
よってO2を消費するため、燃焼温度の高い運転状態で
は、第６図示の点線で示すように酸素センサの空燃比制
御点がH2濃度が小（図中実線）のときに比べてリーン側
に大きくずれてしまう。This H 2 consumes O 2 by the reaction of H 2 + 1 / 2O 2 → H 2 O in the platinum catalyst layer, so under operating conditions where the combustion temperature is high, the oxygen sensor becomes empty as shown by the dotted line in FIG. ratio control points are concentration of H 2 greatly shifted to the lean side as compared with the case of the small (solid line in the figure).
このため、空燃比のリーン化によって窒素酸化物NOxの
排出量が増大し排気特性が悪化するという問題がある。Therefore, there is a problem in that the exhaust amount of nitrogen oxide NOx increases due to the lean air-fuel ratio, and the exhaust characteristics deteriorate.
本発明は上記の実情に鑑みてなされたもので、燃焼温度
高温運転状態でのNOx発生量を抑制できるアルコール燃
料使用内燃機関の空燃比制御装置を提供することを目的
とする。The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an air-fuel ratio control device for an internal combustion engine that uses alcohol fuel and that can suppress the amount of NOx generated in a high combustion temperature operating state.
〈問題点を解決するための手段〉 このため本発明は第１図に示すように、排気系に設けた
酸素センサからの信号に基づいて検出される実際の空燃
比を目標空燃比に近づけるように機関への燃料供給量を
フィードバック制御して空燃比を制御するアルコール燃
料使用内燃機関の空燃比制御装置において、空燃比制御
点が互いに異なる第１酸素センサと第２酸素センサを排
気系に設けると共に、機関運転状態を検出する機関運転
状態検出手段と、該機関運転状態検出手段が燃焼温度の
高い運転状態を検出したとき空燃比検出用酸素センサを
空燃比制御点が第１酸素センサよりリッチ側にある第２
酸素センサに切換制御する酸素センサ切換制御手段とを
備えて構成した。<Means for Solving Problems> Therefore, according to the present invention, as shown in FIG. 1, the actual air-fuel ratio detected based on the signal from the oxygen sensor provided in the exhaust system is made close to the target air-fuel ratio. In an air-fuel ratio control device for an alcohol-fuel-used internal combustion engine that controls the air-fuel ratio by feedback controlling the fuel supply amount to the engine, a first oxygen sensor and a second oxygen sensor having different air-fuel ratio control points are provided in the exhaust system. At the same time, the engine operating state detecting means for detecting the engine operating state, and the oxygen sensor for detecting the air-fuel ratio when the engine operating state detecting means detects an operating state with a high combustion temperature, the air-fuel ratio control point is richer than the first oxygen sensor. Second on the side
And an oxygen sensor switching control means for switching control to the oxygen sensor.
〈作用〉 上記の構成において、通常の運転状態では空燃比制御点
が理論空燃比にある第１酸素センサを用いて空燃比検出
を行い、機関運転状態検出手段が燃焼温度高温運転状態
を検出したときには、切換制御手段によって第１酸素セ
ンサより空燃比制御点がリッチ側にある第２酸素センサ
に切換えて空燃比検出を行う。これにより、燃焼温度高
温運転時における空燃比制御点のリーン側へのずれ巾を
従来よりも少なくすることができるため、NOxの発生を
抑制することができるようになる。<Operation> In the above-mentioned configuration, in the normal operating condition, the air-fuel ratio control point detects the air-fuel ratio using the first oxygen sensor whose stoichiometric air-fuel ratio is set, and the engine operating condition detecting means detects the combustion temperature high temperature operating condition. At times, the switching control means switches to the second oxygen sensor whose air-fuel ratio control point is on the rich side of the first oxygen sensor to detect the air-fuel ratio. As a result, the deviation of the air-fuel ratio control point toward the lean side during high combustion temperature operation can be made smaller than in the conventional case, so that the generation of NOx can be suppressed.
〈実施例〉 以下、本発明の一実施例を図面に基づいて説明する。<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.
本実施例のハードウェア構成を示す第２図において、機
関本体１の吸気通路２に介装された吸入空気流量Ｑを検
出するエアフローメータ３と、機関回転数Ｎを検出する
クランク角センサ等の回転数センサ４とからの各検出信
号をコントロールユニット５に入力する。In FIG. 2 showing the hardware configuration of the present embodiment, an air flow meter 3 for detecting an intake air flow rate Q interposed in an intake passage 2 of an engine body 1, a crank angle sensor for detecting an engine speed N, and the like. Each detection signal from the rotation speed sensor 4 is input to the control unit 5.
コントロールユニット５では、内蔵されたマイクロコン
ピュータにより前記両検出信号に基づいて基本燃料噴射
量Tpを演算し、この演算された基本燃料噴射量Tpを、図
示しない水温センサからの冷却水温等機関運転状態に応
じた各種補正係数COEF,排気通路６に装着した第１及び
第２酸素センサ7,8のうちそのときの運転状態に対応し
て選択されている一方の酸素センサからの酸素濃度検出
信号に基づいて設定される空燃比フィードバック補正係
数α及びバッテリ電圧に基づく電圧補正分Tsにより補正
して最終的な燃料噴射量Tiを演算する。そして、このTi
に対応する燃料噴射信号を吸気通路２のスロットル弁９
上流側に装着した燃料供給手段としての燃料噴射弁10に
出力してTiに相当する量の燃料を供給する。In the control unit 5, the built-in microcomputer calculates the basic fuel injection amount Tp based on the both detection signals, and the calculated basic fuel injection amount Tp is used for the engine operating state such as the cooling water temperature from a water temperature sensor (not shown). Correction coefficient COEF according to the above, the oxygen concentration detection signal from one of the first and second oxygen sensors 7 and 8 mounted in the exhaust passage 6 that is selected corresponding to the operating state at that time. Based on the air-fuel ratio feedback correction coefficient α and the voltage correction amount Ts based on the battery voltage, the final fuel injection amount Ti is calculated. And this Ti
The fuel injection signal corresponding to the throttle valve 9 in the intake passage 2
The fuel is supplied to the fuel injection valve 10 as the fuel supply means mounted on the upstream side to supply the fuel in an amount corresponding to Ti.
また、コントロールユニット５は、例えばエアフローメ
ータ３の吸入空気流量検出信号の変化率に基づいて急加
速状態か否かを判定すると共に、回転数センサ４からの
機関回転数Ｎと演算により求めた基本燃料噴射量Tpとに
より高速状態か否かを判定し、急加速時又は高速時には
燃焼温度が高い運転状態と判断して空燃比検出用酸素セ
ンサを空燃比制御点が理論空燃比にある第１酸素センサ
７から該第１酸素センサ７より空燃比制御点がリッチ側
にある第２酸素センサ８側に切換制御する。従って、エ
アフローメータ3,回転数センサ４が運転状態検出手段を
構成し、コントロールユニット５が空燃比フィードバッ
ク制御手段及び酸素センサ切換制御手段に相当してい
る。尚、11はスロットル弁９の開度を検出するスロット
ルセンサである。Further, the control unit 5 determines whether or not it is in a rapid acceleration state based on, for example, the rate of change of the intake air flow rate detection signal of the air flow meter 3, and determines the engine speed N from the rotation speed sensor 4 and the calculated basic value. The fuel injection amount Tp is used to determine whether or not the engine is in a high speed state, and it is determined that the combustion temperature is high during rapid acceleration or high speed, and the oxygen sensor for detecting the air-fuel ratio is set to the stoichiometric air-fuel ratio. Switching control is performed from the oxygen sensor 7 to the side of the second oxygen sensor 8 whose air-fuel ratio control point is on the rich side of the first oxygen sensor 7. Therefore, the air flow meter 3 and the rotation speed sensor 4 constitute the operating state detecting means, and the control unit 5 corresponds to the air-fuel ratio feedback control means and the oxygen sensor switching control means. Reference numeral 11 is a throttle sensor for detecting the opening of the throttle valve 9.
次に第１及び第２酸素センサについて説明する。Next, the first and second oxygen sensors will be described.
第１酸素センサ７は従来と同様で第３図のような構成に
なっている。The first oxygen sensor 7 is similar to the conventional one and has a structure as shown in FIG.
即ち、先端部を閉塞した酸化ジルコニウム（ZrO2）を主
成分とするセラミック管21の内表面と外表面の各一部に
白金（Pt）ペーストを塗布した後、セラミック管21を焼
成することで起電力取出し用の内側電極22と外側電極23
とを形成してある。更に、外側電極23上に白金を装着し
て白金触媒層24を形成し、その上からマグネシウムスピ
ネル等の酸化金属を溶射して白金触媒層24を保護するた
めの保護層25を形成してなる。That is, by applying platinum (Pt) paste to each part of the inner surface and the outer surface of the ceramic tube 21 whose main part is zirconium oxide (ZrO 2 ) with the tip closed, the ceramic tube 21 is baked. Inner electrode 22 and outer electrode 23 for extracting electromotive force
And are formed. Further, platinum is mounted on the outer electrode 23 to form a platinum catalyst layer 24, and a protective layer 25 for protecting the platinum catalyst layer 24 is formed by spraying an oxide metal such as magnesium spinel on the platinum catalyst layer 24. .
第２酸素センサ８は、前記第１酸素センサ７の保護層25
内に、例えば白金（Pt），パラジウム（Pd）の酸化触媒
金属とロジウム（Rh）の還元触媒金属を含有させて保護
層が形成され、その他の構成は第１酸素センサ７と同じ
である。The second oxygen sensor 8 is a protective layer 25 of the first oxygen sensor 7.
A protective layer is formed by containing, for example, an oxidation catalyst metal such as platinum (Pt) or palladium (Pd) and a reduction catalyst metal such as rhodium (Rh), and other configurations are the same as those of the first oxygen sensor 7.
この第２酸素センサ８によれば、メタノールの分解によ
って発生したH2は保護層内の酸化触媒金属Pt,Pdによっ
て排気中のO2と反応（H2＋1/2O2→H2O）するため、白金
触媒層表面にはほとんど到達せず、白金触媒層における
H2の影響を取除くことができ空燃比制御点のリーン側へ
のずれが抑制できる。同時に排気中のNOxは、保護層内
の還元触媒金属Rhの作用により排気中の未燃成分である
CO,HCと次式にように反応する。According to the second oxygen sensor 8, H 2 generated by the decomposition of methanol reacts with O 2 in the exhaust gas by the oxidation catalyst metals Pt and Pd in the protective layer (H 2 + 1 / 2O 2 → H 2 O). Therefore, the surface of the platinum catalyst layer hardly reaches the surface of the platinum catalyst layer.
The influence of H 2 can be removed, and the deviation of the air-fuel ratio control point to the lean side can be suppressed. At the same time, NOx in the exhaust is an unburned component in the exhaust due to the action of the reduction catalyst metal Rh in the protective layer.
It reacts with CO and HC as follows.
NOx＋CO→N2＋CO2 NOx＋HC→N2＋H2O＋CO2 この結果、白金触媒層でO2と反応するCO,HCが減少しそ
の分O2濃度が増大することになる。NOx + CO → N 2 + CO 2 NOx + HC → N 2 + H 2 O + CO 2 As a result, CO and HC that react with O 2 in the platinum catalyst layer decrease, and the O 2 concentration increases accordingly.
このようなことから、セラミック管内外のO2濃度差が減
少し、理論空燃比よりリッチ側でリーン検出がなされる
こととなり、第１酸素センサ７に比べて空燃比制御点が
リッチ側に存在することになる。As a result, the O 2 concentration difference between the inside and outside of the ceramic tube decreases, and lean detection is performed on the rich side with respect to the theoretical air-fuel ratio, and the air-fuel ratio control point is on the rich side compared to the first oxygen sensor 7. Will be done.
次に第４図のフローチャートに基づいて作用を説明す
る。Next, the operation will be described based on the flowchart of FIG.
ステップ（図中Ｓで示し以下同様とする）１では、吸入
空気流量Q,機関回転数Ｎ等の各種検出信号を読込み、こ
れに基づいてTp,COEF,Tsを設定する。In step (indicated by S in the figure and the same applies hereinafter) 1, various detection signals such as the intake air flow rate Q and the engine speed N are read, and Tp, COEF, Ts are set based on these signals.
ステップ２では、燃焼温度の高い運転状態、例えば急加
速時又は所定以上の高速運転時か否かを判定する。ここ
で、NOの判定のときはステップ３へ進み、第１酸素セン
サ７を選択し、ステップ４でフラグＦを０としステップ
10で第１酸素センサ７からの検出信号に基づいて空燃比
フィードバック制御を行う。In step 2, it is determined whether or not the operating state is high in combustion temperature, for example, during rapid acceleration or during high-speed operation above a predetermined level. Here, in the case of NO determination, the process proceeds to step 3, the first oxygen sensor 7 is selected, and the flag F is set to 0 in step 4
At 10, air-fuel ratio feedback control is performed based on the detection signal from the first oxygen sensor 7.
一方、燃焼温度が高温の運転状態のときはステップ２の
判定がYESとなりステップ５に進む。On the other hand, when the combustion temperature is high, the determination in step 2 is YES and the process proceeds to step 5.
ステップ５では第２酸素センサ８を選択する。In step 5, the second oxygen sensor 8 is selected.
ステップ６ではフラグＦの判定を行い、フラグＦ＝０の
ときは第１酸素センサ７から第２酸素センサ８への切換
直後であることからステップ７で酸素センサ出力のスラ
イスレベルを予め定めた所定値にダウンする。これは同
一スライスレベルに対して第１酸素センサ７と第２酸素
センサ８との空燃比制御点の急変により空燃比が大きく
ずれ運転性に悪影響を及ぼす。従って、第１酸素センサ
７から第２酸素センサ８への切換え直後でスライスレベ
ルを所定値まで下げ空燃比制御点の急変を防いでいる。In step 6, the flag F is determined. When the flag F = 0, it means that the first oxygen sensor 7 has been switched to the second oxygen sensor 8 immediately after. Therefore, in step 7, the slice level of the oxygen sensor output is predetermined. Down to value. This causes a large change in the air-fuel ratio due to a sudden change in the air-fuel ratio control points of the first oxygen sensor 7 and the second oxygen sensor 8 for the same slice level, which adversely affects the drivability. Therefore, immediately after switching from the first oxygen sensor 7 to the second oxygen sensor 8, the slice level is lowered to a predetermined value to prevent a sudden change in the air-fuel ratio control point.
次に、ステップ８ではフラグＦ＝１としステップ10で第
２酸素センサ８の検出信号に基づいて空燃比フィードバ
ック制御を行う。Next, in step 8, the flag F = 1 is set, and in step 10, air-fuel ratio feedback control is performed based on the detection signal of the second oxygen sensor 8.
そして、第２酸素センサ８に基づく空燃比フィードバッ
ク制御の２回目以降では、フラグＦ＝１であるからステ
ップ６からステップ９に進み徐々にスライスレベルをア
ップし最終的には第１酸素センサ７と同一のスライスレ
ベルまで上げる。Then, after the second time of the air-fuel ratio feedback control based on the second oxygen sensor 8, since the flag F = 1, the process proceeds from step 6 to step 9 to gradually increase the slice level and finally to the first oxygen sensor 7. Raise to the same slice level.
かかる空燃比制御によれば、第５図の実線で示すように
H2濃度が小さくその影響が小さい領域Ａの間では、第１
酸素センサ７を使用し、H2濃度が増大しその影響が大に
なる領域Ｂでは第２酸素センサ８を使用して空燃比フィ
ードバック制御を行う。これにより、空燃比制御点のリ
ーン側へのずれを少なくできNOxの増大を防ぐことがで
きる。また、低速時等に従来の第１酸素センサ７を使用
することによって、空燃比リッチ状態で増大するCOの発
生を防ぐことができる。According to such air-fuel ratio control, as shown by the solid line in FIG.
In the area A where the H 2 concentration is small and the influence is small,
The oxygen sensor 7 is used, and in the region B where the H 2 concentration increases and its influence becomes large, the second oxygen sensor 8 is used to perform air-fuel ratio feedback control. As a result, the deviation of the air-fuel ratio control point to the lean side can be reduced and the increase of NOx can be prevented. Further, by using the conventional first oxygen sensor 7 at a low speed or the like, it is possible to prevent the generation of CO that increases in the air-fuel ratio rich state.
〈発明の効果〉 以上述べたように本発明によれば、通常の酸素センサと
これよりリッチ側に空燃比制御点のある酸素センサを設
け、メタノールの分解により発生するH2の濃度が低い低
温運転領域では通常の酸素センサを使用し、H2濃度の高
い運転領域ではリッチ制御用の酸素センサを使用して空
燃比フィードバック制御を行う構成としたので、アルコ
ール燃料使用機関において高温運転領域で発生し易いNO
xの発生量を抑制でき、排気特性の悪化を防ぐことがで
きる。<Effects of the Invention> As described above, according to the present invention, a normal oxygen sensor and an oxygen sensor having an air-fuel ratio control point on the rich side thereof are provided, and the concentration of H 2 generated by the decomposition of methanol is low at low temperatures. Since the normal oxygen sensor is used in the operating range and the oxygen sensor for rich control is used in the operating range where the H 2 concentration is high, the air-fuel ratio feedback control is performed. Easy to do NO
The amount of x generated can be suppressed, and deterioration of exhaust characteristics can be prevented.
第１図は本発明の構成を説明するブロック図、第２図は
本発明の一実施例を示すハードウェア構成図、第３図は
酸素センサの構成図、第４図は同上実施例のフローチャ
ート、第５図は同上実施例の作用を説明する図、第６図
は従来の動作を説明する図である。 １……機関本体、２……吸気通路、３……エアフローメ
ータ、４……回転数センサ、５……コントロールユニッ
ト、６……排気通路、７……第１酸素センサ、８……第
２酸素センサ、10……燃料噴射弁FIG. 1 is a block diagram for explaining the configuration of the present invention, FIG. 2 is a hardware configuration diagram showing an embodiment of the present invention, FIG. 3 is a configuration diagram of an oxygen sensor, and FIG. 4 is a flow chart of the same embodiment. , FIG. 5 is a diagram for explaining the operation of the above embodiment, and FIG. 6 is a diagram for explaining the conventional operation. 1 ... Engine body, 2 ... Intake passage, 3 ... Air flow meter, 4 ... Rotation speed sensor, 5 ... Control unit, 6 ... Exhaust passage, 7 ... First oxygen sensor, 8 ... Second Oxygen sensor, 10 ... Fuel injection valve
Claims (1)
づいて検出される実際の空燃比を目標空燃比に近づける
ように機関への燃料供給量をフィードバック制御して空
燃比を制御するアルコール燃料使用内燃機関の空燃比制
御装置において、空燃比制御点が互いに異なる第１酸素
センサと第２酸素センサを排気系に設けると共に、機関
運転状態を検出する機関運転状態検出手段と、該機関運
転状態検出手段が燃焼温度の高い運転状態を検出したと
き空燃比検出用酸素センサを空燃比制御点が第１酸素セ
ンサよりリッチ側にある第２酸素センサに切換制御する
酸素センサ切換制御手段とを備えて構成したことを特徴
とするアルコール燃料使用内燃機関の空燃比制御装置。Claim: What is claimed is: 1. An alcohol for controlling the air-fuel ratio by feedback-controlling the amount of fuel supplied to the engine so that the actual air-fuel ratio detected based on a signal from an oxygen sensor provided in the exhaust system approaches a target air-fuel ratio. In an air-fuel ratio control apparatus for a fuel-using internal combustion engine, a first oxygen sensor and a second oxygen sensor having different air-fuel ratio control points are provided in an exhaust system, and an engine operating state detecting means for detecting an engine operating state and the engine operating state are provided. And an oxygen sensor switching control means for switching the air-fuel ratio detecting oxygen sensor to a second oxygen sensor whose air-fuel ratio control point is richer than the first oxygen sensor when the state detecting means detects an operating state in which the combustion temperature is high. An air-fuel ratio control device for an internal combustion engine using alcohol fuel, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27585587A JPH0697001B2 (en) | 1987-11-02 | 1987-11-02 | Air-fuel ratio controller for internal combustion engine using alcohol fuel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27585587A JPH0697001B2 (en) | 1987-11-02 | 1987-11-02 | Air-fuel ratio controller for internal combustion engine using alcohol fuel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01121539A JPH01121539A (en) | 1989-05-15 |
| JPH0697001B2 true JPH0697001B2 (en) | 1994-11-30 |
Family
ID=17561371
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP27585587A Expired - Lifetime JPH0697001B2 (en) | 1987-11-02 | 1987-11-02 | Air-fuel ratio controller for internal combustion engine using alcohol fuel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0697001B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101720346B (en) | 2007-05-29 | 2012-02-29 | 汉高有限公司 | Adhesive detection method |
| EP2657495A4 (en) * | 2010-12-24 | 2014-07-30 | Toyota Motor Co Ltd | DEVICE AND METHOD FOR ERROR DETECTION OF INTER-CYLINDER AIR TO FUEL RATIO |
-
1987
- 1987-11-02 JP JP27585587A patent/JPH0697001B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01121539A (en) | 1989-05-15 |
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