JPH01232142A - Air-fuel ratio control device for internal combustion engine - Google Patents
Air-fuel ratio control device for internal combustion engineInfo
- Publication number
- JPH01232142A JPH01232142A JP5903488A JP5903488A JPH01232142A JP H01232142 A JPH01232142 A JP H01232142A JP 5903488 A JP5903488 A JP 5903488A JP 5903488 A JP5903488 A JP 5903488A JP H01232142 A JPH01232142 A JP H01232142A
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- feedback control
- internal combustion
- combustion 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.)
- Granted
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 305
- 238000002485 combustion reaction Methods 0.000 title claims description 42
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 52
- 238000001514 detection method Methods 0.000 claims description 70
- 239000003054 catalyst Substances 0.000 claims description 14
- 238000010792 warming Methods 0.000 abstract description 7
- 238000000034 method Methods 0.000 description 68
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 67
- 229910052760 oxygen Inorganic materials 0.000 description 67
- 239000001301 oxygen Substances 0.000 description 67
- 230000008569 process Effects 0.000 description 63
- 238000002347 injection Methods 0.000 description 33
- 239000007924 injection Substances 0.000 description 33
- 239000000498 cooling water Substances 0.000 description 18
- 239000007789 gas Substances 0.000 description 14
- 230000003197 catalytic effect Effects 0.000 description 12
- 230000003247 decreasing effect Effects 0.000 description 12
- 230000006866 deterioration Effects 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 230000004043 responsiveness Effects 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- QRSFFHRCBYCWBS-UHFFFAOYSA-N [O].[O] Chemical compound [O].[O] QRSFFHRCBYCWBS-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010687 lubricating oil Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 102100022354 FAS-associated factor 2 Human genes 0.000 description 1
- 101000824586 Homo sapiens FAS-associated factor 2 Proteins 0.000 description 1
- 101100108349 Solanum lycopersicum TDR5 gene Proteins 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 235000021185 dessert Nutrition 0.000 description 1
- 239000002828 fuel tank Substances 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
Description
【発明の詳細な説明】
二匪Ω旦皿
［産業上の利用分野］
本発明は、内燃機関の排気系に介装された三元触媒の上
流側および下流側に酸素濃度センサ等の空燃比センサを
配設し、上流側空燃比センサの検出結果に基づく空燃比
フィードバック制御に加えて、下流側空燃比センサの検
出結果に基づく空燃比フィードバック制御を実行する内
燃機関の空燃比制御装置に関する。Detailed Description of the Invention [Industrial Field of Application] The present invention provides an air-fuel ratio sensor such as an oxygen concentration sensor on the upstream and downstream sides of a three-way catalyst installed in the exhaust system of an internal combustion engine. The present invention relates to an air-fuel ratio control device for an internal combustion engine that includes a sensor and executes air-fuel ratio feedback control based on the detection result of a downstream air-fuel ratio sensor in addition to air-fuel ratio feedback control based on the detection result of an upstream air-fuel ratio sensor.
［従来の技術］
通常の空燃比フィードバック制御装置、所謂、シングル
酸素）調度センサシステムでは、酸素濃度を検出する空
燃比センサとしての酸素濃度センサを燃焼室近傍に配設
するため、触媒コンバータの上流側である排気マニホー
ルドに設けている。しかし、酸素濃度センサの出力特性
の固体差により、空燃比の制御精度向上には限界があっ
た。そこで、上記酸素濃度センサの出力特性の固体差、
さらに、燃料噴射弁等の構成部品の固体差、経時変化、
経年変化等に起因する制御精度低下に対する対策として
、触媒コンバータの下流側に下流側酸素濃度センサを配
設し、上記触媒コンバータの上流側に配設された上流測
酸素澗度センサの検出信号に基づく空燃比フィードバッ
ク制御に加えて、上記下流側酸素濃度センサの検出信号
に基づく空燃比フィードパ・ンク制弾を実行する、所謂
、ダブル酸素濃度センサシステムが知られている。該ダ
ブル酸素濃度センサシステムでは、下流側酸素濃度セン
サの応答性は、上流側酸素濃度センサの応答性より低い
が、次のような理由により、出力特性が比較的安定して
いる。[Prior Art] In a normal air-fuel ratio feedback control device, the so-called single oxygen (oxygen) preparation sensor system, an oxygen concentration sensor as an air-fuel ratio sensor for detecting oxygen concentration is arranged near the combustion chamber, so it is placed upstream of the catalytic converter. It is installed on the side of the exhaust manifold. However, due to individual differences in the output characteristics of oxygen concentration sensors, there has been a limit to the improvement in air-fuel ratio control accuracy. Therefore, the individual differences in the output characteristics of the oxygen concentration sensor,
Furthermore, individual differences in component parts such as fuel injection valves, changes over time,
As a countermeasure against deterioration of control accuracy due to aging, etc., a downstream oxygen concentration sensor is installed downstream of the catalytic converter, and the detection signal of the upstream oxygen concentration sensor installed upstream of the catalytic converter is A so-called double oxygen concentration sensor system is known that performs air-fuel ratio feed pump control based on the detection signal of the downstream oxygen concentration sensor in addition to the air-fuel ratio feedback control based on the above-described air-fuel ratio feedback control. In the double oxygen concentration sensor system, although the responsiveness of the downstream oxygen concentration sensor is lower than that of the upstream oxygen concentration sensor, the output characteristics are relatively stable for the following reasons.
（ａ） 触媒コンバータの下流側の排気温度は上流側
に比べて低いので、下流側酸素濃度センサに対する熱的
悪影響が比較的少ない。(a) Since the exhaust gas temperature on the downstream side of the catalytic converter is lower than that on the upstream side, there is relatively little adverse thermal effect on the downstream oxygen concentration sensor.
（ｂ） 酸素濃度センサの出力特性に悪影響を及ぼす
排気中の有害物質は、触媒コンバータ内部で吸着される
ので、下流側の排気から酸素濃度センサが悪影響を受け
ることは比較的少ない。(b) Harmful substances in the exhaust gas that adversely affect the output characteristics of the oxygen concentration sensor are adsorbed inside the catalytic converter, so the oxygen concentration sensor is relatively unlikely to be adversely affected by the downstream exhaust gas.
（Ｃ） 触媒コンバータの下流側の排気は、充分混合
されているため、排気中の酸素濃度はほぼ平衡状態に近
いので、酸素濃度センサにより比較的正確に検出できる
。(C) Since the exhaust gas on the downstream side of the catalytic converter is sufficiently mixed, the oxygen concentration in the exhaust gas is almost in an equilibrium state, so that it can be detected relatively accurately by the oxygen concentration sensor.
このため、２つの酸素濃度センサの検出信号に基づく空
燃比フィードバック制御（所謂、ダブル酸素濃度センサ
システム）は、上流側酸素濃度センサの出力特性の悪化
を、下流側＃素澗度センサの検出信号により補正できる
。すなわち、第９図に黒塗で示すように、ダブル酸素）
震度センサシステムでは、上流側酸素濃度センサの出力
特性が悪化しても、排気中の有害成分（ＨＣ，Ｃｏ、
Ｎ。For this reason, air-fuel ratio feedback control based on the detection signals of two oxygen concentration sensors (so-called double oxygen concentration sensor system) detects deterioration in the output characteristics of the upstream oxygen concentration sensor using the detection signal of the downstream oxygen concentration sensor. It can be corrected by In other words, double oxygen (as shown in black in Figure 9)
In the seismic intensity sensor system, even if the output characteristics of the upstream oxygen concentration sensor deteriorate, harmful components (HC, Co,
N.
Ｘ）の排出量はほとんど増加せず、排気特性の悪化は見
られない。一方、同図に白抜きで示すように、出力特性
悪化時のシングル酸素）震度センサシステムでは、排気
中の有害成分がかなり増加し、排気特性の悪化が顕著に
現れる。このように、ダブル酸素）震度センサシステム
では、下流側酸素濃度センサの出力特性が安定していれ
は、良好な排気特性が補償される。There was almost no increase in the emission amount of X), and no deterioration in exhaust characteristics was observed. On the other hand, as shown in white in the figure, in the case of the single oxygen (oxygen) seismic intensity sensor system when the output characteristics deteriorate, the harmful components in the exhaust gas increase considerably, and the deterioration of the exhaust characteristics becomes noticeable. In this way, in the double oxygen/seismic intensity sensor system, as long as the output characteristics of the downstream oxygen concentration sensor are stable, good exhaust characteristics are compensated.
上述のようなダブル酸素）震度センサシステムでは、第
１０図に示すように、従来より使用されている上流側酸
素濃度センサ検出信号Ｖ１に応じて空燃比補正係数ＦＡ
Ｆを算出する際に使用する空燃比フィードバック制御定
数（例えば、リーンスキップｆｆ１Ｒ５Ｌ、リッチスキ
ップ量Ｒ５Ｒ）を、下流側酸素濃度センサ検出信号に基
づいて補正している。しかし、例えば、機関暖機時等、
下流側酸素）震度センサ検出信号に基づく制御定数の補
正演算が停止され、上流側酸素濃度センサの検出信号に
応じた空燃比フィードバック制御のみを実行する場合も
ある。このようなときには、同図に示すように、制御定
数、例えば、リッチスキップ量、リーンスキップ量等は
、予め定められた一定値（Ｒ５ＬＯ，Ｒ３ＲＯ）、ある
いは、上記補正演算実行中に学習記憶されていた値を使
用し、上流側酸素濃度センサの検出信号に応じた空燃比
フィードバック制御のみを実行する技術が知られている
。In the double oxygen intensity sensor system as described above, as shown in FIG.
The air-fuel ratio feedback control constants (for example, lean skip ff1R5L, rich skip amount R5R) used when calculating F are corrected based on the downstream oxygen concentration sensor detection signal. However, for example, when warming up the engine, etc.
In some cases, the correction calculation of the control constant based on the detection signal of the downstream oxygen/intensity sensor is stopped, and only the air-fuel ratio feedback control according to the detection signal of the upstream oxygen concentration sensor is executed. In such a case, as shown in the figure, the control constants, such as rich skip amount, lean skip amount, etc., are set to predetermined constant values (R5LO, R3RO) or are learned and stored during execution of the above correction calculation. There is a known technique in which only the air-fuel ratio feedback control is performed in accordance with the detection signal of the upstream oxygen concentration sensor using the previously determined value.
このようなものとして、例えば、 「内燃機関の空燃比
制御装置」 （特開昭６１−２３４２４１号公報）等が
提案されている。すなわち、下流側空燃比センサの出力
に応じて空燃比フィードバック制御定数であるスキップ
量を予め定められた一定の補正量づつ増減補正し、該補
正されたスキップ量を用いて上流側空燃比センサの出力
に応じた空燃比補正量を演算して機関の空燃比を調整し
、上流側空燃比センサの劣化に伴う応答速度の低下を防
止する技術である。この技術では、下流側空燃比センサ
の出力に応じて空燃比フィードバック制御定数であるス
キップ量を補正しないときは、スキ・ンブ量を予め定め
られた一定値に設定していた。As such a device, for example, an “air-fuel ratio control device for an internal combustion engine” (Japanese Unexamined Patent Publication No. 61-234241) has been proposed. That is, the skip amount, which is an air-fuel ratio feedback control constant, is increased or decreased by a predetermined constant correction amount in accordance with the output of the downstream air-fuel ratio sensor, and the corrected skip amount is used to increase or decrease the skip amount, which is an air-fuel ratio feedback control constant. This technology calculates an air-fuel ratio correction amount according to the output to adjust the air-fuel ratio of the engine, and prevents a decrease in response speed due to deterioration of the upstream air-fuel ratio sensor. In this technique, when the skip amount, which is an air-fuel ratio feedback control constant, is not corrected in accordance with the output of the downstream air-fuel ratio sensor, the skimming amount is set to a predetermined constant value.
［発明が解決しようとする課！］
しかし、下流側空燃比センサの出力に応じて空燃比フィ
ードバック制御定数を算出しないで、−定値、あるいは
、学習値に設定し、上流側酸素温度センサの検出信号に
応じた空燃比フィードバック制御のみを実行する場合、
例えば、内燃機関が暖機過程にあるときは、希薄側（Ｌ
ｅａｎ）へのスキップ量が大きい値に設定されていると
、空燃比は希薄側（Ｌｅａｎ）に過補正され、ドライバ
ビリティが悪化するという問題点があった。[The problem that the invention tries to solve! ] However, instead of calculating the air-fuel ratio feedback control constant according to the output of the downstream air-fuel ratio sensor, it is set to a - constant value or a learned value, and only air-fuel ratio feedback control is performed according to the detection signal of the upstream oxygen temperature sensor. If you run
For example, when the internal combustion engine is warming up, the lean side (L
If the skip amount to (lean) is set to a large value, the air-fuel ratio is overcorrected to the lean side (lean), resulting in a problem that drivability deteriorates.
また、下流側空燃比センサの出力に応じた空燃比フィー
ドバック制御定数の算出を行なわない場合で、内燃機関
が暖機過程にあるときは、各種制御定数の制限幅を、下
流側空燃比センサの出力に応じて空燃比フィードバック
制御定数を算出する場合の所定制限幅よりも狭く設定し
た非算出時制限幅に変更する改良技術も考案された。と
ころが、全暖機過程に亘って、非算出時制限幅が一定で
あったため、該非算出時制限幅に規制される空燃比フィ
ードバック制御定数が必ずしも最適値にはならず、特に
、暖機初期時等、冷却水温度が低い場合には、ドライバ
ビリティの低下を招き易く、上記改良技術も未だ充分な
ものではなかった。In addition, when the air-fuel ratio feedback control constant is not calculated according to the output of the downstream air-fuel ratio sensor and the internal combustion engine is in the warm-up process, the limit widths of various control constants are An improved technique has also been devised in which the air-fuel ratio feedback control constant is changed to a non-calculation limit width that is set narrower than the predetermined limit width when calculating the air-fuel ratio feedback control constant according to the output. However, since the non-calculation limit width was constant throughout the entire warm-up process, the air-fuel ratio feedback control constant, which is regulated by the non-calculation limit width, did not necessarily reach the optimal value, especially at the initial stage of warm-up. etc., when the cooling water temperature is low, drivability tends to deteriorate, and the above-mentioned improved technology is still not sufficient.
さらに、各種制御定数の制限幅を狭く設定すると、空燃
比補正係数による空燃比補正能力の低下により、空燃比
の制御中心値が大きく変動し、排気特性の悪化を生じる
という問題もあった。Furthermore, if the limit widths of the various control constants are set narrowly, there is a problem in that the control center value of the air-fuel ratio fluctuates greatly due to a decrease in the air-fuel ratio correction ability by the air-fuel ratio correction coefficient, resulting in deterioration of exhaust characteristics.
本発明は、下流側空燃比センサの出力に応じた空燃比フ
ィードバック制御定数の算出を中止し、上流側空燃比セ
ンサの検出信号に応じた空燃比フィードバック制御のみ
を実行する場合、暖機過程における空燃比の希薄側（Ｌ
ｅａｎ）への大きな移行による運転性能（ドライバビリ
ティ）の悪化を好適に抑制する内燃機関の空燃比制御装
置の提供を目的とする。 ′
発明の構成
［課題を解決するための手段］
上記目的を達成するためになされた本発明は、第１図に
例示するように、
内燃機関Ｍ１の排気通路に介装され、排気を浄化する三
元触媒Ｍ２と、
該三元触媒Ｍ２の上流側の排気通路に配設され、排気中
の特定成分）震度を検出する上流側空燃比検出手段Ｍ３
と、
上記三元触ｆｆ１Ｍ２の下流側の排気通路に配設され、
排気中の特定成分濃度を検出する下流側空燃比検出手段
Ｍ４と、
外部から指令される制御量に従って、上記内燃機関Ｍ１
の空燃比を調節する空燃比調節手段Ｍ５と、
上記内燃機関Ｍ１の、少なくとも暖機状態を含む運転状
態を検出する運転状態検出手段Ｍ６と、該運転状態検出
手段Ｍ６の検出した運転状態に基づいて、上記内燃機関
Ｍ１の運転状態が、上記下流側空燃比検出手段Ｍ４の検
出結果に基づく空燃比フィードバック制御定数算出可能
な算出可能運転状態にあるか否かを判定する判定手段Ｍ
７と、該判定手段Ｍ７により算出可能運転状態にあると
判定されたときに、上記下流側空燃比検出手段Ｍ４の検
出結果に応じて、空燃比フィードバック制御定数を算出
する制御定数算出手段Ｍ８と、該制御定数算出手段Ｍ８
の算出した空燃比フィードバック制御定数を所定制限幅
以内に制限し、更新記憶する学習手段Ｍ９と、
該学習手段Ｍ９の記憶している空燃比フィードバック制
御定数および前記上流側空燃比検出手段Ｍ３の検出結果
に応じて決定した制御量を上記空燃比調節手段Ｍ５に指
令する空燃比フィードバッり制御手段ＭＩＯと、
を具備した内燃機関の空燃比制御装置であって、さらに
、上記内燃機関Ｍ１の暖機完了以前で、上記判定手段Ｍ
７により算出可能運転状態にないと判定されたときは、
上記学習手段Ｍ９の記憶している空燃比フィードパ・ン
ク″＄Ｊ ｔＢｕ定数の所定制限幅を、上記運転状態検
出手段Ｍ６の検出した暖機状態の暖機完了への進行過程
に応じて、上記所定制限幅より狭い初期制限幅から該所
定制限幅までの範囲で増加補正する補正手段Ｍｌｌを備
えたことを特徴とする内燃機関の空燃比制御装置を要旨
とするものである。゛
上流側空燃比検出手段Ｍ３とは、三元触媒Ｍ２の上流側
の排気中の特定成分濃度を検出するものである。例えば
、排気中の、酸素、−酸化炭素等の特定成分濃度を検出
するガスセンサやリーンミクスチャセンサにより実現で
きる。In the present invention, when the calculation of the air-fuel ratio feedback control constant according to the output of the downstream side air-fuel ratio sensor is stopped and only the air-fuel ratio feedback control according to the detection signal of the upstream side air-fuel ratio sensor is executed, The lean side of the air-fuel ratio (L
An object of the present invention is to provide an air-fuel ratio control device for an internal combustion engine that suitably suppresses deterioration in driving performance (driveability) due to a large shift to ean). 'Structure of the Invention [Means for Solving the Problems] The present invention, which has been made to achieve the above object, has the following features: As illustrated in FIG. a three-way catalyst M2; and an upstream air-fuel ratio detection means M3 disposed in the exhaust passage upstream of the three-way catalyst M2 to detect the seismic intensity of a specific component in the exhaust gas.
and arranged in the exhaust passage downstream of the three-way contact ff1M2,
downstream side air-fuel ratio detection means M4 that detects the concentration of a specific component in the exhaust; and the internal combustion engine M1 according to a control amount commanded from the outside.
an air-fuel ratio adjusting means M5 for adjusting the air-fuel ratio of the internal combustion engine M1; an operating state detecting means M6 for detecting the operating state of the internal combustion engine M1, including at least a warm-up state; and based on the operating state detected by the operating state detecting means M6. determining means M for determining whether or not the operating state of the internal combustion engine M1 is in a computable operating state in which an air-fuel ratio feedback control constant can be calculated based on the detection result of the downstream air-fuel ratio detecting means M4;
7, and a control constant calculating means M8 for calculating an air-fuel ratio feedback control constant according to the detection result of the downstream air-fuel ratio detecting means M4 when it is determined by the determining means M7 that the operating state is in a computable operation state. , the control constant calculation means M8
a learning means M9 that limits the calculated air-fuel ratio feedback control constant to within a predetermined limit width and updates and stores the air-fuel ratio feedback control constant; and detecting the air-fuel ratio feedback control constant stored in the learning means M9 and the upstream air-fuel ratio detection means M3. An air-fuel ratio control device for an internal combustion engine, comprising: an air-fuel ratio feedback control means MIO that instructs the air-fuel ratio adjustment means M5 to control a control amount determined according to the result; Before the machine is completed, the above judgment method M
When it is determined that the calculation is not possible according to 7,
The predetermined limit width of the air-fuel ratio feed pump "$J tBu constant stored in the learning means M9 is determined according to the progress of the warm-up state detected by the operating state detecting means M6 to the completion of warm-up. The gist of the present invention is an air-fuel ratio control device for an internal combustion engine, characterized in that it is equipped with a correction means Mll that performs incremental correction in the range from an initial limit width narrower than a predetermined limit width to the predetermined limit width. The fuel ratio detection means M3 is for detecting the concentration of a specific component in the exhaust gas on the upstream side of the three-way catalyst M2. This can be achieved using a mixture sensor.
下流側空燃比検出手段Ｍ４とは、三元触媒Ｍ２の下流側
の排気中の特定成分濃度を検出するものである。例えば
、上記上流側空燃比検出手段Ｍ３と同様な構成により実
現できる。The downstream air-fuel ratio detection means M4 detects the concentration of a specific component in the exhaust gas downstream of the three-way catalyst M2. For example, it can be realized by a configuration similar to that of the upstream air-fuel ratio detection means M3.
空燃比調節手段Ｍ５とは、外部から指令される制御量に
従って、内燃機関Ｍ１の空燃比を調節するものである。The air-fuel ratio adjusting means M5 adjusts the air-fuel ratio of the internal combustion engine M1 according to a control amount commanded from the outside.
例えば、燃料噴射置割ｔｆｆｉｌ可能な燃料噴射弁、ブ
リードエア流量制御可能な気化器、流量制御可能な２次
空気導入装置等により実現できる。For example, it can be realized by a fuel injection valve capable of controlling the fuel injection position, a carburetor capable of controlling the flow rate of bleed air, a secondary air introduction device capable of controlling the flow rate, and the like.
運転状態検出手段Ｍ６とは、内燃機関Ｍ１の、少なくと
も暖機状態を含む運転状態を検出するものである。例え
は、機関温度を測定可能な機関温度センサ、あるいは、
水温センサ、潤滑用オイル温度センサ、その他、回転速
度センサ、スロットルポジションセンサ、始動時からの
経過時間を計測するタイマ等により実現できる。The operating state detection means M6 detects the operating state of the internal combustion engine M1, including at least a warm-up state. For example, an engine temperature sensor that can measure engine temperature, or
This can be realized using a water temperature sensor, a lubricating oil temperature sensor, a rotation speed sensor, a throttle position sensor, a timer that measures the elapsed time from the start, etc.
判定手段Ｍ７とは、運転状態検出手段Ｍ６の検出した運
転状態に基づいて、内燃機関Ｍ１の運転状態が、下流側
空燃比検出手段Ｍ４の検出結果に基づく空燃比フィード
バック制御定数算出可能な算出可能運転状態にあるか否
かを判定するものである。例えば、冷却水温度、各種燃
料増量の有無、スロットルバルブ開度、下流側酸素濃度
センサの状態およびエンジン負荷等に基づいて判定する
よう構成できる。The determining means M7 is capable of determining the operating state of the internal combustion engine M1 based on the operating state detected by the operating state detecting means M6, such that an air-fuel ratio feedback control constant can be calculated based on the detection result of the downstream air-fuel ratio detecting means M4. This is to determine whether or not the vehicle is in a driving state. For example, the determination can be made based on the cooling water temperature, whether or not there is an increase in the amount of various fuels, the opening degree of the throttle valve, the state of the downstream oxygen concentration sensor, the engine load, etc.
制御定数算出手段Ｍ８とは、判定手段Ｍ７により算出可
能運転状態にあると判定されたときに、下流側空燃比検
出手段Ｍ４の検出結果に応じて、空燃比フィードバック
制御定数を算出するものである。例えば、下流側酸素濃
度センサ検出信号に基づいて、スキ・ンブ量、積分定数
、デイレイ時間、上流側酸素濃度センサ検出信号の比較
電圧等を増減補正して算出するよう構成できる。The control constant calculating means M8 calculates an air-fuel ratio feedback control constant according to the detection result of the downstream air-fuel ratio detecting means M4 when it is determined by the determining means M7 that the operating state is in which calculation is possible. . For example, the calculation may be performed by increasing or decreasing the skim amount, integral constant, delay time, comparison voltage of the upstream oxygen concentration sensor detection signal, etc. based on the downstream oxygen concentration sensor detection signal.
学習手段Ｍ９とは、制御定数算出手段Ｍ８の算出した空
燃比フィードバック制御定数を所定制限幅以内に制限し
、更新記憶するものである。例えば、上記各種の制御定
数を、各々上限値と下限値とで定まる制限幅内に制限す
る処理を実行する演算器および学習記憶する記憶素子に
より構成できる。The learning means M9 limits the air-fuel ratio feedback control constant calculated by the control constant calculating means M8 to within a predetermined limit range, and updates and stores the constant. For example, it can be configured by a computing unit that executes processing to limit the various control constants described above within a limit range determined by an upper limit value and a lower limit value, and a storage element that performs learning and storage.
空燃比フィードパ・ンク制御手段ＭＩＯとは、学習手段
Ｍ９の記憶している空燃比フィードバック制御定数およ
び上流側空燃比検出手段Ｍ３の検出結果に応じて決定し
た制御量を空燃比調節手段Ｍ５に指令するものである。The air-fuel ratio feed pump/punk control means MIO instructs the air-fuel ratio adjustment means M5 to control the amount determined according to the air-fuel ratio feedback control constant stored in the learning means M9 and the detection result of the upstream air-fuel ratio detection means M3. It is something to do.
例えば、下流側酸素濃度に基づいて算出される、リーン
・リッチ両スキップ量、積分定数、リーン・リッチ両遅
延時間および空燃比信号比較電圧等と上流側酸素温度と
から求めた空燃比フィードバック補正係数に応じて燃料
随躬量を決定して指令するよう構成できる。For example, the air-fuel ratio feedback correction coefficient is calculated from the lean and rich skip amounts, integral constants, lean and rich delay times, air-fuel ratio signal comparison voltage, etc. calculated based on the downstream oxygen concentration, and the upstream oxygen temperature. It can be configured to determine and command the amount of fuel to be consumed depending on the amount of fuel to be consumed.
補正手段Ｍｌｌとは、内燃機関Ｍ１の暖機完了以前で、
判定手段Ｍ７により算出可能運転状態にないと判定され
たときは、学習手段Ｍ９の記憶している空燃比フィード
バック制御定数の所定制限幅を、運転状態検出手段Ｍ６
の検出した暖機状態の暖機完了への進行過程に応じて、
所定制限幅より狭い初期制限幅から所定制限幅までの範
囲で増加補正するものである。例えば、冷却水温度、あ
るいは、機関温度、もしくは、潤滑油温度と制限幅境界
値との関係を規定した演算式やマツプにより構成できる
。The correction means Mll is before the completion of warm-up of the internal combustion engine M1,
When the determining means M7 determines that the operating state is not one in which calculation is possible, the predetermined limit width of the air-fuel ratio feedback control constant stored in the learning means M9 is set to the operating state detecting means M6.
Depending on the progress of the detected warm-up state to completion of warm-up,
The increasing correction is performed in the range from the initial limit width narrower than the predetermined limit width to the predetermined limit width. For example, it can be configured by an arithmetic expression or map that defines the relationship between the cooling water temperature, engine temperature, or lubricating oil temperature and the limit width boundary value.
上記判定手段Ｍ７、制御定数算出手段Ｍ８、学習手段Ｍ
９、空燃比フィードパ・ンク制御手段Ｍ１０および補正
手段Ｍｌｌは、例えば、各々独立したディスクリートな
論理回路により実現できる。The above-mentioned determination means M7, control constant calculation means M8, learning means M
9. The air-fuel ratio feed pump control means M10 and the correction means Mll can be realized, for example, by independent discrete logic circuits.
また、例えば、周知のＣＰＵ、ＲＯＭ、ＲＡＭ等を中心
に、その他の周辺回路素子と共に論理演算回路として構
成され、予め定められた処理手順に従って、上記各手段
を実現するよう構成しても良い。Further, for example, the circuit may be configured as a logic operation circuit mainly using a well-known CPU, ROM, RAM, etc. together with other peripheral circuit elements, and may be configured to implement the above-mentioned means according to a predetermined processing procedure.
［作用］
本発明の内燃機関の空燃比制御装置は、第１図に例示す
るように、運転状態検出手段Ｍ６の検出した、内燃機関
Ｍ１・の、少なくとも暖機状態を含む運転状態に基づい
て、上記内燃機関Ｍ１の運転状態が、該内燃機関Ｍ１の
排気通路に介装された三元触媒Ｍ２の下流側の排気中の
特定成分濃度を検出する下流側空燃比検出手段Ｍ４の検
出結果に基づく空燃比フィードバック制御定数算出可能
な算出可能運転状態にあると判定手段Ｍ７により判定さ
れたときに、上記下流側空燃比検出手段Ｍ４の検出結果
に応じて、制御定数算出手段Ｍ８の算出した空燃比フィ
ードバック制御定数を学習手段Ｍ９は所定制限幅以内に
制限して更新記憶し、該記憶されている空燃比フィード
パ・ンク制御定数および上記三元触媒Ｍ２の上流側の排
気中の特定成分）詔度を検出する上流側空燃比検出手段
Ｍ３の検出結果に応じて決定した制御量を空燃比フィー
ドバック制御手段ＭＩＯが、上記内燃機関Ｍ１の空燃比
を調節する空燃比調節手段Ｍ５に指令するに際し、上記
内燃機関Ｍ１の暖機完了以前で、上記判定手段Ｍ７によ
り算出可能運転状態にないと判定されたときは、上記学
習手段Ｍ９の記憶している空燃比フィードバック制御定
数の所定制限幅を、上記運転状態検出手段Ｍ６の検出し
た暖機状態の暖機完了への進行過程に応じて、上記所定
制限幅より狭い期間制限幅から該所定制限幅までの範囲
で、補正手段Ｍｌｌが増加補正するよう働く。[Operation] As illustrated in FIG. 1, the air-fuel ratio control device for an internal combustion engine of the present invention operates based on the operating state of the internal combustion engine M1, including at least the warm-up state, detected by the operating state detecting means M6. , the operating state of the internal combustion engine M1 is determined by the detection result of the downstream air-fuel ratio detection means M4, which detects the concentration of a specific component in the exhaust downstream of the three-way catalyst M2, which is installed in the exhaust passage of the internal combustion engine M1. When the determination means M7 determines that the air-fuel ratio feedback control constant based on the calculation is possible, the air-fuel ratio feedback control constant calculated by the control constant calculation means M8 is The learning means M9 updates and stores the fuel ratio feedback control constant within a predetermined limit range, and updates the stored air-fuel ratio feed pump control constant and a specific component in the exhaust gas upstream of the three-way catalyst M2. When the air-fuel ratio feedback control means MIO instructs the air-fuel ratio adjustment means M5 that adjusts the air-fuel ratio of the internal combustion engine M1 to control the amount determined according to the detection result of the upstream air-fuel ratio detection means M3 that detects the air-fuel ratio, If the determination means M7 determines that the internal combustion engine M1 is not in a computable operating state before the warm-up of the internal combustion engine M1 is completed, the predetermined limit width of the air-fuel ratio feedback control constant stored in the learning means M9 is set to According to the progress of the warm-up state detected by the operating state detection means M6 toward the completion of warm-up, the correction means Mll performs an incremental correction in the range from the period limit width narrower than the predetermined limit width to the predetermined limit width. work.
すなわち、暖機完了以前で、上流側空燃比に基づく空燃
比フィードバック制御のみを実行し、下流側空燃比に応
じて空燃比フィードバック制御定数を算出しないときは
、学習記憶されている空燃比フィードバック制御定数の
制限幅を暖機過程の進行に伴って拡大し、過大な空燃比
フィードバック制御定数に起因する暖機中の空燃比の希
薄側への大きな変動を抑制するのである。In other words, if only the air-fuel ratio feedback control based on the upstream air-fuel ratio is executed before the warm-up is completed, and the air-fuel ratio feedback control constant is not calculated according to the downstream air-fuel ratio, the air-fuel ratio feedback control that has been learned and stored will be executed. The limit range of the constant is expanded as the warm-up process progresses, thereby suppressing large fluctuations in the air-fuel ratio toward the lean side during warm-up caused by an excessive air-fuel ratio feedback control constant.
従って、本発明の内燃機関の空燃比制御装置は、暖機完
了以前で、上流側空燃比に基づく空燃比フィードバック
制御のみを実行し、下流側空燃比に応じて空燃比フィー
ドバック制御定数を算出しないときでも、該空燃比フィ
ードパ・ンク制御定数を暖機状態に応じた適切な値に制
限するよう働く。Therefore, the air-fuel ratio control device for an internal combustion engine of the present invention executes only the air-fuel ratio feedback control based on the upstream air-fuel ratio before the warm-up is completed, and does not calculate the air-fuel ratio feedback control constant according to the downstream air-fuel ratio. Even when the engine is warmed up, the air-fuel ratio feed pump control constant is limited to an appropriate value depending on the warm-up condition.
以上のように本発明の各構成要素が作用することにより
、本発明の技術的課題が解決される。The technical problems of the present invention are solved by each component of the present invention acting as described above.
［実施例コ
次に本発明の好適な実施例を図面に基づいて詳細に説明
する。本発明の一実施例であるエンジンの空燃比制御装
置のシステム構成を第２図に示す。[Embodiment] Next, a preferred embodiment of the present invention will be described in detail based on the drawings. FIG. 2 shows a system configuration of an engine air-fuel ratio control device that is an embodiment of the present invention.
同図に示すように、エンジンの空燃比制御装置１は、エ
ンジン２およびこれを制御する電子制’＋８装置（以下
、単にＥＣＵと呼ぶ。）３から構成されている。As shown in the figure, an engine air-fuel ratio control device 1 includes an engine 2 and an electronic control unit (hereinafter simply referred to as ECU) 3 that controls the engine 2.
エンジン２は、シリンダ４、ピストン５およびシリンダ
ヘッド６から燃焼室７を形成し、該燃焼室７には点火プ
ラグ８が配設されている。The engine 2 includes a cylinder 4, a piston 5, and a cylinder head 6 to form a combustion chamber 7, and a spark plug 8 is disposed in the combustion chamber 7.
該エンジン２の吸気系は、上記燃焼室７と吸気バルブ９
を介して連通ずる吸気ボー）１０、吸気管１１、吸入空
気の脈動を吸収するサージタンク１２、アクセルペダル
１３に連動して吸入空気量を調節するスロットルバルブ
１４およびエアクリーナ１５から構成されている。The intake system of the engine 2 includes the combustion chamber 7 and the intake valve 9.
It is comprised of an intake bow 10 that communicates with the engine through an intake pipe 11, a surge tank 12 that absorbs pulsation of intake air, a throttle valve 14 that adjusts the amount of intake air in conjunction with an accelerator pedal 13, and an air cleaner 15.
上記エンジン２の排気系は、上記燃焼室７と排気バルブ
１６を介して連通ずる排気ポート１７、排気マニホール
ド１８、三元触媒を充填した触媒コンバータ１９および
排気管２０から構成されている。The exhaust system of the engine 2 includes an exhaust port 17 communicating with the combustion chamber 7 via an exhaust valve 16, an exhaust manifold 18, a catalytic converter 19 filled with a three-way catalyst, and an exhaust pipe 20.
上記エンジン２の点火系は、点火に必要な高電圧を出力
するイグニッションコイルを備えたイグナイタ２１およ
び図示しないクランク軸に連動して上記イグナイタ２１
で発生した高電圧を点火プラグに分配供給するディスト
リビュータ２２より構成されている。The ignition system of the engine 2 includes an igniter 21 equipped with an ignition coil that outputs a high voltage necessary for ignition, and an igniter 21 that is connected to a crankshaft (not shown).
It is composed of a distributor 22 that distributes and supplies the high voltage generated by the spark plug to the spark plug.
上記エンジン２の燃料系統は、燃料を貯蔵するためのフ
ューエルタンク２３、該燃料を圧送するフューエルポン
プ２４、圧送された燃料を上記吸気ボート１０近傍に噴
射する電磁式の燃料噴射弁２５から構成されている。The fuel system of the engine 2 includes a fuel tank 23 for storing fuel, a fuel pump 24 for pumping the fuel, and an electromagnetic fuel injection valve 25 for injecting the pumped fuel into the vicinity of the intake boat 10. ing.
エンジンの空燃比制御装置１は検出器として、上述した
吸気管１１のスロットルバルブ１４上流側に設けられて
吸入空気量を計測するエアフロメータ３１、該エアフロ
メータ３１内部に設けられて吸入空気温度を測定する吸
気温センサ３２、上記スロットルバルブ】４に連動して
該スロットルバルブ１４の開度を検出するスロットルポ
ジションセンサ３３、上記スロットルバルブ１４の全閉
状態を検出するアイドルスイッチ３４、シリンダブロッ
ク４ａの冷却系統に配設されて冷却水温度を検出する水
温センサ３５、排気マニホールド１日内に設けられて上
記触媒コンバータ１９に流人する前の排気中の残存酸素
ｉ震度を検出する上流側酸素濃度センサ３６、排気管２
０内に設けられて上記触媒コンバータ１９から流出した
排気中の残存酸素）震度を検出する下流側酸素濃度セン
サ３７、上述したディストリビュータ２２０カムシヤフ
トの１回転毎に、すなわち、図示しないクランク軸の２
回転毎に基準信号を出力する気筒判別センサ３８、上記
ディストリビュータ２２のカムシャフトの１７２４回転
毎に、すなわち、クランク角Ｏ°から３０°の整数倍毎
に回転角信号を出力する回転速度センサを兼ねた回転角
センサ３９を備えている。The engine air-fuel ratio control device 1 includes an air flow meter 31 which is installed upstream of the throttle valve 14 in the intake pipe 11 and measures the amount of intake air, and a detector which is installed inside the air flow meter 31 to measure the intake air temperature. An intake air temperature sensor 32 to measure, a throttle position sensor 33 which detects the opening degree of the throttle valve 14 in conjunction with the throttle valve 4, an idle switch 34 which detects the fully closed state of the throttle valve 14, and an idle switch 34 of the cylinder block 4a. A water temperature sensor 35 is installed in the cooling system to detect the cooling water temperature, and an upstream oxygen concentration sensor is installed in the exhaust manifold and detects the residual oxygen i seismic intensity in the exhaust gas before being transferred to the catalytic converter 19. 36, exhaust pipe 2
The downstream oxygen concentration sensor 37 is installed within the catalytic converter 19 and detects the seismic intensity (residual oxygen in the exhaust gas flowing out from the catalytic converter 19).
The cylinder discrimination sensor 38 outputs a reference signal every rotation, and also serves as a rotation speed sensor that outputs a rotation angle signal every 1724 rotations of the camshaft of the distributor 22, that is, every integer multiple of the crank angle 0° to 30°. A rotation angle sensor 39 is provided.
上記各センサおよびスイッチの検出信号はＥＣＵ３に入
力され、該ＥＣＵ３はエンジン２を制御する。ＥＣＵ３
は、ＣＰＵ３ａ、ＲＯＭ３ｂ、ＲＡ Ｍ ３ ｃ 、バ
ックアップＲＡＭ３ｄ、 タイマ３ｅを中心に論理演
算回路として構成され、コモンバス３ｆを介して人出カ
ポ−）３ｇに接続されて外部との人出力を行なう。ＣＰ
Ｕ３ａは、上述したエアフロメータ３１、吸気温センサ
３２、スロットルポジションセンサ３３の検出信号をＡ
／Ｄ変換器３ｈおよび人出カポ−）３ｇを介して、アイ
ドルスイッチ３４の検出信号を人出カポ−）３ｇを介し
て、気筒判別センサ３８、回転角センサ３９の検出信号
を波形整形回路３ｉおよび入出カポ−）３ｇを介して、
水温センサ３５、上流側酸素濃度センサ３６、下流側酸
素濃度センサ３７の検出信号をＡ／Ｄ変換器３ｊおよび
人出力ボート３ｇを介して、各々人力する。一方、ＣＰ
Ｕ３ａは、人出力部３ｇおよび駆動回路３ｍを介してイ
グナイタ２１を駆動制御する。さらに、ＣＰＬＪ３ａは
人出力ｉｆ３３ ｇ、ダウンカウンタ３ｎ、フリップフ
ロップ回路３ｐおよび駆動回路３ｒを介して燃料噴射弁
２５を駆動側ｆａｌｌする。すなわち、ＣＰＵ３ａで算
出された燃料噴射量ＴＡＵに相当する値がダウンカウン
タ３ｎにプリセットされると共に、フリップフロップ回
Ｂ３ｐもセ・ントされる。このため、駆動回路３ｒが燃
料噴射弁２５を開弁し、燃料噴射が開始される。一方、
ダウンカウンタ３ｎがクロック信号を計数し、最後にそ
のキャリアウド端子がハイレベル（１）になると、フリ
ップフロップ回路３ｐがセットされて駆動回路３ｒは燃
料噴射弁２５を閉弁し、燃料噴射が終了する。Detection signals from each of the sensors and switches described above are input to the ECU 3, and the ECU 3 controls the engine 2. ECU3
The circuit is constructed as a logic operation circuit mainly including a CPU 3a, a ROM 3b, a RAM 3c, a backup RAM 3d, and a timer 3e, and is connected to the output capo 3g via a common bus 3f to perform output with the outside. C.P.
U3a outputs the detection signals of the air flow meter 31, intake air temperature sensor 32, and throttle position sensor 33 mentioned above.
The detection signal of the idle switch 34 is outputted via the /D converter 3h and the turnout capo 3g to the detection signal of the cylinder discrimination sensor 38 and the rotation angle sensor 39 to the waveform shaping circuit 3i. and input/output capo) through 3g,
The detection signals of the water temperature sensor 35, the upstream oxygen concentration sensor 36, and the downstream oxygen concentration sensor 37 are each manually inputted via the A/D converter 3j and the human output boat 3g. On the other hand, C.P.
U3a drives and controls the igniter 21 via the human output section 3g and the drive circuit 3m. Further, the CPLJ 3a causes the fuel injection valve 25 to fall to the drive side via the human output if33g, the down counter 3n, the flip-flop circuit 3p, and the drive circuit 3r. That is, a value corresponding to the fuel injection amount TAU calculated by the CPU 3a is preset in the down counter 3n, and the flip-flop number B3p is also set. Therefore, the drive circuit 3r opens the fuel injection valve 25, and fuel injection is started. on the other hand,
The down counter 3n counts the clock signals, and finally, when its carrier terminal becomes high level (1), the flip-flop circuit 3p is set and the drive circuit 3r closes the fuel injection valve 25, ending fuel injection. do.
乙のように、燃料噴射量ＴＡ［Ｊに応じた量の燃料がエ
ンジン２に供給される。なお、上記ＥＣＵ３は、イグニ
・ンションスイッチ４０を介して車載バッテリ４１から
電力の供給を受けて作動する。また、上記バックアップ
ＲＡＭ３ｄは、上記イグニッションスイ・ンチ４０を介
さず、図示しない経路より電力が与えられ、該イグニッ
ションスイッチ４０の状態にかかわらずメモリ内容が保
持される様に構成されている。As shown in Figure B, an amount of fuel corresponding to the fuel injection amount TA[J is supplied to the engine 2. Note that the ECU 3 operates by receiving power from an on-vehicle battery 41 via an ignition switch 40. Further, the backup RAM 3d is configured to receive power from a path not shown, not through the ignition switch 40, and to retain the memory contents regardless of the state of the ignition switch 40.
次に、上記ＥＣＵ３の実行する第１の空燃比フィードバ
ック制御処理を第３図（１）、 （２）の、第２の空
燃比フィードバック制御処理を第５図（１）、 （２
）の、燃料噴剥制ｔＨ処理を第７図の、各フローチャー
トに基づいて説明する。Next, the first air-fuel ratio feedback control process executed by the ECU 3 is shown in FIGS. 3(1) and (2), and the second air-fuel ratio feedback control process is shown in FIGS. 5(1) and (2).
), the fuel injection stripping control tH process will be explained based on the respective flowcharts in FIG.
まず、第１の空燃比フィードパ・ンク制御処理を第３図
（１）、 （２）に示すフローチャートに基づいて説
明する。氷菓１の空燃比フィードバック制御処理は、Ｅ
ＣＵ３の起動後、所定時間（例えば、４［ｍ５ｅｃ］）
毎に実行される。まず、ステップ１０２では、既述した
各センサの検出信号に基づく各データを読み込む処理が
行われる。続くステップ１０６では、第１の空燃比フィ
ードバック制御実行条件が成立するか否かを判定し、肯
定判断されるとステップ１０日に進み、一方、否定判断
されると、空燃比補正係数ＦＡＦの値を前回の制御終了
時の値とし、−旦、本箱１の空燃比フィードバック制御
処理を終了する。なお、空燃比補正係数ＦＡＦの値を、
一定値、前回の制御終了までの平均値、バックアップＲ
ＡＭ３ｄに記憶されている学習値等に設定しても良い。First, the first air-fuel ratio feed pump control process will be explained based on the flowcharts shown in FIGS. 3(1) and (2). The air-fuel ratio feedback control process for frozen dessert 1 is E
After starting CU3, a predetermined time (for example, 4 [m5ec])
executed every time. First, in step 102, a process of reading each data based on the detection signal of each sensor described above is performed. In the subsequent step 106, it is determined whether the first air-fuel ratio feedback control execution condition is satisfied, and if the affirmative determination is made, the process proceeds to step 10. On the other hand, if the negative determination is made, the value of the air-fuel ratio correction coefficient FAF is determined. is set to the value at the end of the previous control, and the air-fuel ratio feedback control process for the bookcase 1 is ended on -day. In addition, the value of the air-fuel ratio correction coefficient FAF is
Constant value, average value until the last control end, backup R
It may also be set to a learning value stored in the AM3d.
ここで、例えば、冷却水温度Ｔｆ−ＩＷが所定温度（例
えは、６０ ［’ ＣＩ ）以下のとき、始動状態、始
動後増量中、暖機増量中、加速増量（非同期噴射）中、
パワー増量中、上流側酸素濃度センサ３６の出力信号Ｖ
１が一度も第１の比較電圧ＶＲＩを横切っていないとき
、等は何れも第１の空燃比フィードバック制御実行条件
不成立である。上記各条件に該当しない、第１の空燃比
フィードバック制御実行条件成立時に実行されるステッ
プ１０日では、上流側酸素濃度センサ３６の検出信号Ｖ
１をＡ／Ｄ変換して読み込む処理が行われる。続くステ
・ンブ１１０では、上流側酸素温度センサ３６の検出信
号Ｖ１が第１の比較電圧ＶＲＩ（例えば、０゜４５ ［
Ｖ］ ’）以下であるか否かを判定し、肯定判断される
と空燃比が希薄側（Ｌｅａｎ）であるとしてステップ１
１２に、一方、否定判断されると空燃比が過ｆａｉ［！
ＩＪ （Ｒｉ ｃ ｈ）であるとしてステップ１２４に
各々進む。空燃比が希薄側（Ｌ ｅ ａ ｎ）であると
きに実行されるステップ１１２では、デイレイカウンタ
ＣＤＬＹの計数値の正負を判定し、正のときはステップ
１１４でデイレイカウンタＣＤＬＹの計数１直を値０に
リセットした後ステップ１１６に進み、一方、負のとき
は、そのままステップ１１６に進む。ステ・ンプ１１６
では、デイレイカウンタＣＤ Ｌ Ｙの計数１直を値１
だけ減算し、続くステップ１１８．１２０で該デイレイ
カウンタＣＤＬＹの計数値を最小値ＴＤＬに制限し、デ
イレイカウンタＣＤＬＹＯ値が最小値ＴＤＬまで減少し
たときは、ステップ１２２で空燃比フラグＦ１を値０（
希薄側（Ｌｅａｎ））にリセットした後、ステップ１４
０に進む。なお、最小値ＴＤＬは、上流側酸素）震度セ
ンサ３６の検出信号ｖ１が過温側（Ｒｉ ｃ ｈ）から
希薄側（Ｌ ｅ ａ ｎ）に変化しても、過温側（Ｒｉ
ｃｈ）であるとの判断を保持するためのリーン遅延時間
であって、負の値に定義されている。一方、上記ステッ
プ１１０で、空燃比が過温側（Ｒｉ ｃ ｈ）であると
判定されたときに実行されるステップ１２４では、デイ
レイカウンタＣＤＬＹの計数値の正負を判定し、負のと
きはステップ１２６でデイレイカウンタＣＤＬＹの計数
値を値０にリセットした後ステップ１２８に進み、一方
、正のときは、そのままステ・ンブ１２８に進む。ステ
ップ１２８では、デイレイカウンタＣＤＬＹの計数値を
値１だり加算し、続くステップ１３０，１３２で該デイ
レイカウンタＣＤＬＹの計数値を最大値ＴＤＲに制限し
、デイレイカウンタＣＤＬＹの計数値が最大値ＴＤＲま
で増加したときは、ステップ１３４で空燃比フラグＦ１
を値１（過濃側（Ｒｉｃｈ））にセットした後、ステッ
プ１４０に進む。なお、最大ｆｌｕ ＴＤＲは、上流側
酸素濃度センサ３６の検出信号Ｖ１が希薄側（Ｌｅａｎ
）から過温側（Ｒｉｃｈ）に変化しても、希薄側（Ｌ
ｅ ａ ｎ）であるとの判断を保持するためのリッチ遅
延時間であもて、正の値に定義されている。Here, for example, when the cooling water temperature Tf-IW is below a predetermined temperature (for example, 60 [' CI ), in the starting state, during increase in amount after starting, during increase in warm-up amount, during accelerated increase in amount (asynchronous injection),
During power increase, the output signal V of the upstream oxygen concentration sensor 36
1 has never crossed the first comparison voltage VRI, etc., the first air-fuel ratio feedback control execution condition is not satisfied. In step 10, which is executed when the first air-fuel ratio feedback control execution condition is satisfied, which does not correspond to each of the above conditions, the detection signal V of the upstream oxygen concentration sensor 36 is
1 is A/D converted and read. In the subsequent step 110, the detection signal V1 of the upstream oxygen temperature sensor 36 is set to a first comparison voltage VRI (for example, 0°45 [
V]') or less, and if it is affirmative, the air-fuel ratio is determined to be on the lean side (Lean) and step 1 is performed.
12, on the other hand, if the judgment is negative, the air-fuel ratio is too high [!
Assuming that IJ (Rich), the process proceeds to step 124. In step 112, which is executed when the air-fuel ratio is on the lean side (Le a n), it is determined whether the count value of the delay counter CDLY is positive or negative, and if it is positive, the count value of the delay counter CDLY is set to 1 in step 114. After resetting to 0, the process proceeds to step 116. On the other hand, if the value is negative, the process directly proceeds to step 116. Step 116
Now, set the count 1 of the delay counter CDLY to the value 1.
Then, in subsequent steps 118 and 120, the count value of the delay counter CDLY is limited to the minimum value TDL, and when the delay counter CDLYO value has decreased to the minimum value TDL, the air-fuel ratio flag F1 is set to the value 0 (
After resetting to the lean side (Lean), step 14
Go to 0. Note that even if the detection signal v1 of the upstream oxygen seismic intensity sensor 36 changes from the overtemperature side (Ri ch) to the lean side (L e a n), the minimum value TDL
This is the lean delay time for maintaining the determination that the current condition is (ch), and is defined as a negative value. On the other hand, in step 124, which is executed when it is determined in step 110 that the air-fuel ratio is on the overtemperature side (Rich), it is determined whether the count value of the delay counter CDLY is positive or negative, and if it is negative, the step At step 126, the count value of the delay counter CDLY is reset to the value 0, and then the process proceeds to step 128. On the other hand, if it is positive, the process directly proceeds to step 128. In step 128, the count value of the delay counter CDLY is incremented by 1, and in subsequent steps 130 and 132, the count value of the delay counter CDLY is limited to the maximum value TDR, and the count value of the delay counter CDLY increases to the maximum value TDR. When this happens, the air-fuel ratio flag F1 is set in step 134.
After setting the value to 1 (Rich side), the process proceeds to step 140. Note that the maximum flu TDR is determined when the detection signal V1 of the upstream oxygen concentration sensor 36 is on the lean side (Lean
) to the overtemperature side (Rich), the lean side (L
The rich delay time is used to maintain the judgment that e a n), and is defined as a positive value.
続くステップ１４０では、空燃比フラグＦ１の値が反転
したか否かを判定し、肯定判断されるとステップ１４２
に、一方、否定判断されるとステップ１４日に、各々進
む。空燃比フラグＦ１の値が反転したときに実行される
ステップ１４２では、過温側（Ｒｉｃｈ）から希薄側（
Ｌｅａｎ）への反転か、希薄側（Ｌ ｅ ａｎ）から過
濃側（Ｒｉｃｈ）への反転かを判定する処理が行われる
。過）２側（Ｒｉ ｃ ｈ）から希薄側（Ｌｅａｎ）へ
の反転時に実行されるステ・ンブ１４４では、空燃比補
正係数ＦＡＦにリッチスキップ量Ｒ９Ｒを加算してスキ
ップ的に増加させ、一方、希薄側（Ｌ ｅ ａ ｎ）か
ら過温側（Ｒｉ ｃ ｈ）への反転時に実行されるステ
ップ１４６では、空燃比補正係数ＦＡＦからリーンスキ
ップ量Ｒ５Ｌを減算してスキップ的に減少させ、各々ス
テップ１５６に進む。また、上記ステップ１４０で空燃
比フラグＦ１の値が反転しないときに実行されるステッ
プ１４８では、希薄側（Ｌｅａｎ）であるか、過濃側（
Ｒｉｃｈ）であるかを判定する処理が行われる。希薄側
（Ｌｅａｎ）であるときに実行されるステ・ンプ１５０
では、空燃比補正係数ＦＡＦにり・ソチ積分定数ＫＩＲ
を加算して徐々に増加させ、一方、過濃側（Ｒｉ ｃ
ｈ）であるときに実行されるステップ１５２では、空燃
比補正係ｖｉＦ Ａ Ｆからリーン積分定数ＫＩＬを減
算して徐々に減少させ、各々ステップ１５６に進む。こ
こで、両積分定数ＫＩＲ，ＫＩＬは、両スキ・ンプ量Ｒ
５Ｒ，Ｒ９Ｌに比較して充分小さく設定されている。従
って、ステップ１４４．１４６では燃料噴射量は迅速に
増減補正され、一方、ステ・ンブ１５０，１５２では燃
料噴射量は徐々に増減補正される。続くステップ１５６
゜１５８では、上記空燃比補正係数ＦＡＦの値を、例え
ば、最大値１．２以下に制限し、さらに、続くステップ
１６０．１６２では、最小値０．８以上に制限し、空燃
比補正係数の値ＦＡＦが何等かの原因により過大、ある
いは、過小になった場合でも、空燃比のオーバリッチ状
態、もしくは、オーバリーン状態への移行を防止する。In the following step 140, it is determined whether the value of the air-fuel ratio flag F1 has been inverted, and if an affirmative determination is made, the process proceeds to step 142.
On the other hand, if a negative determination is made, the process proceeds to step 14. In step 142, which is executed when the value of the air-fuel ratio flag F1 is reversed, the change is made from the overtemperature side (Rich) to the lean side (
A process is performed to determine whether the reversal is from the lean side (Lean) or from the lean side (L e an) to the rich side (Rich). In step 144, which is executed when reversing from the rich side (Rich) to the lean side (Lean), the rich skip amount R9R is added to the air-fuel ratio correction coefficient FAF to increase it in a skip manner. In step 146, which is executed at the time of reversal from the lean side (Le a n) to the overtemperature side (Rich), the lean skip amount R5L is subtracted from the air-fuel ratio correction coefficient FAF to decrease it in a skip manner, and the lean skip amount R5L is decreased in a skip manner. Proceed to 156. Further, in step 148, which is executed when the value of the air-fuel ratio flag F1 is not inverted in step 140, it is determined whether the air-fuel ratio flag F1 is on the lean side (Lean) or on the rich side (
Rich). Step 150 executed when on the lean side (Lean)
Then, the air-fuel ratio correction coefficient FAF and the Sochi integral constant KIR
is gradually increased by adding
In step 152, which is executed when h), the lean integral constant KIL is subtracted from the air-fuel ratio correction factor viF A F to gradually decrease it, and the process proceeds to step 156 in each case. Here, both integral constants KIR and KIL are both skimp amounts R
It is set sufficiently small compared to 5R and R9L. Therefore, in steps 144 and 146, the fuel injection amount is rapidly increased or decreased, while in steps 150 and 152, the fuel injection amount is gradually increased or decreased. Following step 156
In step 158, the value of the air-fuel ratio correction coefficient FAF is limited to, for example, a maximum value of 1.2 or less, and further, in subsequent steps 160 and 162, the value of the air-fuel ratio correction coefficient is limited to a minimum value of 0.8 or more, and the value of the air-fuel ratio correction coefficient is Even if the value FAF becomes too large or too small for some reason, the air-fuel ratio is prevented from shifting to an overrich state or an overlean state.
次にステップ１６４に進み、上記のように算出された空
燃比補正係ｒＪＩＦ Ａ ＦをＲＡＭ３ｃおよびバック
アップＲＡＭ３ｄに記憶した後、−旦、本箱１の空燃比
フィードバック制御処理を終了する。以後、本箱１の空
燃比フィードパ・ンク制御処理は所定時間毎に、上記ス
テップ１０２〜１６４を繰り返して実行する。Next, the process proceeds to step 164, and after storing the air-fuel ratio correction coefficient rJIF AF calculated as described above in the RAM 3c and the backup RAM 3d, the air-fuel ratio feedback control process for the bookcase 1 is ended. Thereafter, the air-fuel ratio feed pump control process for the bookcase 1 is executed by repeating steps 102 to 164 at predetermined intervals.
次に、上記制御の様子の一例を、第４図のタイミングチ
ャートに従って説明する。時刻ｔ１に、上流側酸素濃度
センサ検出信号に基づく空燃比信号Ａ／Ｆが希薄側（Ｌ
ｅ ａ ｎ）から過濃側（Ｒｉａｈ）に変化すると、
デイレイカウンタＣＤＬＹの計数値はリセット後、カウ
ントアツプされ、リッチ遅延時間ＴＤＲ経過後の時刻ｔ
２に最大（ｉ ＴＤＲに到達する。すると、遅延処理後
の空燃比信号Ａ／Ｆｄ（空燃比フラグＦ１の値）が、希
薄側（Ｌｅａｎ）から過）肩側（Ｒｉｃｈ）に変化する
。Next, an example of the above control will be explained according to the timing chart of FIG. 4. At time t1, the air-fuel ratio signal A/F based on the upstream oxygen concentration sensor detection signal is on the lean side (L
When it changes from e a n) to the rich side (Riah),
The count value of the delay counter CDLY is counted up after being reset, and the count value is counted up at time t after the rich delay time TDR has elapsed.
2, the air-fuel ratio signal A/Fd (value of the air-fuel ratio flag F1) after the delay process changes from the lean side (Lean) to the shoulder side (Rich).
また、時刻ｔ３に、上流側酸素濃度センサ検出信号に基
づく空燃比信号Ａ／Ｆが過）肩側（Ｒｉ ｃ ｈ）から
希薄側（Ｌｅａｎ）に変化すると、デイレイカウンタＣ
ＤＬＹの計数値はリセ・ント後、カウントダウンされ、
リーン遅延時間（−ＴＤＬ）経過後の時刻ｔ４に最小値
ＴＤＬに到達する。すると、遅延処理後の空燃比信号Ａ
／Ｆｄ（空燃比フラグＦ１の値）が、過濃側（Ｒｉ ｃ
ｈ）から希薄側（Ｌｅａｎ）に変化する。しかし、例
えば、上流側酸素濃度センサ検出信号に基づく空燃比信
号Ａ／Ｆが、時刻ｔ５．ｔ６．ｔ７のようにり・ソチ遅
延時間ＴＤＲより短い期間で反転すると、デイレイカウ
ンタＣＤＬＹの計数値が最大ｆｉＴＤＲへ到達する時間
が延長され、時刻ｔ８に至って遅延処理後の空燃比信号
Ａ／Ｆｄが反転する。すなわち、遅延処理後の空燃比信
号Ａ／Ｆｄ（空燃比フラグＦ１の値）は、上流側酸素濃
度センサ検出信号に基づく空燃比信号Ａ／Ｆよりも安定
した値となる。Further, at time t3, when the air-fuel ratio signal A/F based on the upstream oxygen concentration sensor detection signal changes from the shoulder side (Ri ch) to the lean side (Lean), the delay counter C
The count value of DLY is counted down after reset,
The minimum value TDL is reached at time t4 after the lean delay time (-TDL) has elapsed. Then, the air-fuel ratio signal A after the delay processing
/Fd (value of air-fuel ratio flag F1) is on the rich side (Ric
h) to the lean side (Lean). However, for example, if the air-fuel ratio signal A/F based on the upstream oxygen concentration sensor detection signal is at time t5. t6. When it is reversed in a period shorter than the delay time TDR as shown in t7, the time for the count value of the delay counter CDLY to reach the maximum fiTDR is extended, and at time t8, the air-fuel ratio signal A/Fd after the delay process is reversed. do. That is, the air-fuel ratio signal A/Fd (the value of the air-fuel ratio flag F1) after the delay processing has a more stable value than the air-fuel ratio signal A/F based on the upstream oxygen concentration sensor detection signal.
このように、比較的安定した遅延処理後の空燃比信号Ａ
／Ｆｄに基づいて、空燃比補正係数ＦＡＦが決定される
。In this way, the relatively stable air-fuel ratio signal A after the delay processing
/Fd, the air-fuel ratio correction coefficient FAF is determined.
次に、第２の空燃比フィードバック制御処理について説
明する。第２の空燃比フィードバック制御処理は、第１
の空燃比フィードバック制御処理の制御定数であるスキ
ップ量Ｒ９Ｒ，Ｒ５Ｌ、積分定数ＫＩＲ，ＫＩＬ、遅延
時間ＴＤＲ，ＴＤＬおよび第１の比較電圧ＶＲＩを変更
する制御を行なうものと、第２の空燃比補正係数ＦＡＦ
２を算出する制御を行なうものがある。Next, the second air-fuel ratio feedback control process will be explained. The second air-fuel ratio feedback control process
Control constants for the air-fuel ratio feedback control process, such as skip amounts R9R, R5L, integral constants KIR, KIL, delay times TDR, TDL, and first comparison voltage VRI, are changed; and a second air-fuel ratio correction. Coefficient FAF
There is one that performs control to calculate 2.
制御定数であるスキップ量Ｒ５Ｒ，Ｒ５Ｌ、積分定数Ｋ
ＩＲ，ＫＩＬ、遅延時間ＴＤＲ，ＴＤＬおよび第１の比
較電圧ＶＲＩを変更する制御では、例えば、リッチスキ
・ンブ量Ｒ９Ｒの増加補正、あるいは、リーンスキップ
量Ｒ９Ｌの減少補正により空燃比を過濃側（Ｒｉ ｃ
ｈ）に制御でき、一方、−リッチスキップ量Ｒ５Ｒの減
少補正、あるいは、リーンスキップ量Ｒ５Ｌの増加補正
により空燃比を希薄側（Ｌｅａｎ）に制御できる。従っ
て、下流側酸素濃度センサ３７の検出信号に応じてリツ
チスキ・ンブｆｆ１Ｒ３Ｒ，あるいは、リーンスキップ
量Ｒ５Ｌの少なくとも一方を補正すると空燃比を制御で
きる。また、例えば、リッチ積分定数ＫＩＲの増加補正
、あるいは、リーン積分定数ＫＩＬの減少補正により空
燃比を過温側（Ｒｉ ｃ ｈ）に制御でき、一方、Ｉル
ンチ積分定数Ｋ Ｉ Ｒの減少補正、あるいは、リーン
積分定数ＫＩＬの増加補正により空燃比を希薄側（Ｌ
ｅ ａ ｎ）に制御できる。Skip amounts R5R, R5L, which are control constants, integral constant K
In the control to change IR, KIL, delay times TDR, TDL, and first comparison voltage VRI, for example, the air-fuel ratio is changed to the rich side ( Ric
h), and on the other hand, the air-fuel ratio can be controlled to the lean side (Lean) by decreasing the -rich skip amount R5R or increasing the lean skip amount R5L. Therefore, the air-fuel ratio can be controlled by correcting at least one of the richness skip ff1R3R or the lean skip amount R5L in accordance with the detection signal of the downstream oxygen concentration sensor 37. Further, for example, the air-fuel ratio can be controlled to the overtemperature side (Rich) by increasing the rich integral constant KIR or decreasing the lean integral constant KIL, while decreasing the I-run integral constant KIR, Alternatively, the air-fuel ratio can be adjusted to the lean side (L
can be controlled to e a n).
このように、下流側酸素温度センサ３７の検出信号に応
じてリッチ積分定数ＫＩＲ５あるいは、リーン積分定数
ＫＩＬの少なくとも一方を補正すると空燃比を制御でき
る。さらに、例えば、リッチ遅延時間ＴＤＲをリーン遅
延時間（−ＴＤＬ）より相対的に大きく設定すると、空
燃比を過温側（Ｒｉｃｈ）に制御でき、一方、リッチ遅
延時間ＴＤＲをリーン遅延時間ＴＤＬより相対的に小さ
く設定すると、空燃比を希薄側（Ｌｅａｎ）に制御でき
る。すなわち、下流側酸素温度センサ３７の検出信号に
応じてリッチ遅延時間ＴＤＲ１あるいは、リーン遅延時
間ＴＤＬの少なくとも一方を補正すると空燃比を制御で
きる。また、例えば、第１の比較電圧ＶＲＩを低下補正
すると、空燃比を希薄側（Ｌｅａｎ）に制御できる。そ
こで、下流側酸ＸｆＦ度センサ３７の検出信号に応じて
第１の比較電圧ＶＲＩを補正しても、空燃比を制御でき
る。ところで、上記スキップ量Ｒ５Ｒ，Ｒ５Ｌ、積分定
数ＫＩＲ，ＫＩＬ、遅延時間ＴＤＲ，ＴＤＬおよび第１
の比較電圧ＶＲＩを下流側酸素温度センサ３７の検出信
号に応じて変更すると、例えば、遅延時間ＴＤＲ，ＴＤ
Ｌの補正は非常に微妙な空燃比制ｉ卸を可能にし、スキ
・ンプ量Ｒ９Ｒ，Ｒ５Ｌは、上記遅延時間ＴＤＲ，ＴＤ
Ｌのように空燃比フィードバック制御周間の延長を伴う
ことなく高い応答性を保持した制御が可能になる。従っ
て、複数の上記制御定数を祁み合わせた制御が有効であ
る。In this way, the air-fuel ratio can be controlled by correcting at least one of the rich integral constant KIR5 or the lean integral constant KIL in accordance with the detection signal of the downstream oxygen temperature sensor 37. Further, for example, if the rich delay time TDR is set relatively larger than the lean delay time (-TDL), the air-fuel ratio can be controlled to the overtemperature side (Rich), while the rich delay time TDR is set relatively larger than the lean delay time TDL. By setting it to a relatively small value, the air-fuel ratio can be controlled to the lean side (Lean). That is, the air-fuel ratio can be controlled by correcting at least one of the rich delay time TDR1 and the lean delay time TDL in accordance with the detection signal of the downstream oxygen temperature sensor 37. Further, for example, if the first comparison voltage VRI is corrected to decrease, the air-fuel ratio can be controlled to the lean side (Lean). Therefore, even if the first comparison voltage VRI is corrected according to the detection signal of the downstream acid XfF degree sensor 37, the air-fuel ratio can be controlled. By the way, the skip amounts R5R, R5L, the integral constants KIR, KIL, the delay times TDR, TDL, and the first
For example, when the comparison voltage VRI is changed according to the detection signal of the downstream oxygen temperature sensor 37, the delay times TDR, TD
The correction of L enables a very delicate air-fuel ratio control, and the skimp amounts R9R and R5L are determined by the above delay times TDR and TD.
Control that maintains high responsiveness is possible without extending the air-fuel ratio feedback control period as in L. Therefore, control that combines a plurality of the above control constants is effective.
次に、第２の空燃比フィードバック制御部処理を第５図
（１）、 （２）に示すフローチャートに基づいて説
明する。氷菓２の空燃比フィードバック制御処理は、Ｅ
ＣＵ３の起動後、所定時間（例えば、５１２［ｍ５ｅｃ
コ）毎に実行され、スキップ量Ｒ９Ｒ，Ｒ９Ｌを補正演
算する。Next, the second air-fuel ratio feedback control section processing will be explained based on the flowcharts shown in FIGS. 5(1) and (2). The air-fuel ratio feedback control process for Hyouka 2 is E
After starting the CU3, a predetermined period of time (for example, 512 [m5ec
(d) is executed to correct the skip amounts R9R and R9L.
まず、ステップ２０２では、既述した各センサの検出信
号に基づく各データを読み込む処理が行われる。続くス
テップ２０４では、空燃比フィードバック制御処理実行
条件が成立するが否かを判定し、肯定判断されるとステ
ップ２０６に進み、一方、否定判断されるとステップ２
３０に進む。First, in step 202, a process of reading each data based on the detection signal of each sensor described above is performed. In the following step 204, it is determined whether the air-fuel ratio feedback control processing execution condition is satisfied or not. If the judgment is affirmative, the process proceeds to step 206, while if the judgment is negative, the process proceeds to step 2.
Proceed to 30.
上記ステップ２０４で、例えば、冷却水温度ＴＦ（Ｗが
所定温度（例えば、６０［°Ｃ］）以下のとき、始動状
態、始動後増量中、暖機増量中、加速増量（非同期噴射
）中、パワー増量中、上流側酸素濃度センサ３６の検出
信号Ｖ１が一度も第１の比較電圧ＶＲＩを横切っていな
いとき、等は何れも空燃比フィードバック制御処理実行
条件不成立である。上記各条件に該当しない、空燃比フ
ィードバック制御処理実行条件成立時にはステップ２０
６以下に進む。ステップ２０６では、冷却水温度ＴＨＷ
が７０ ［°Ｃ］を上回るか否か、ステ・ンブ２０８で
はスロットルバルブ１４が非全閉状態にあるか否か、ス
テップ２１０では下流側酸素温度センサ３７が活性状態
にあるか否か、ステップ２１２では下流側酸素）農産セ
ンサが正常であるか否か、ステ・ンプ２１４ではエンジ
ン２の負荷が所定負荷Ｘ１以上あるか否かを各々判定し
、全てのステップで肯定判断されると、第２の空燃比フ
ィードバック制御実行条件成立と見なしてステップ２１
６以下に進み、一方、何れか一つのステップで否定判断
されると、第２の空燃比フィードバック制御実行条件不
成立と見なしてステ・シブ２３０以下に進む。In step 204, for example, when the cooling water temperature TF (W is below a predetermined temperature (e.g. 60 [°C]), in the starting state, during increase in amount after startup, during increase in warm-up amount, during accelerated increase in amount (asynchronous injection), During power increase, when the detection signal V1 of the upstream oxygen concentration sensor 36 never crosses the first comparison voltage VRI, the air-fuel ratio feedback control processing execution condition is not satisfied.Each of the above conditions does not apply. , step 20 when the air-fuel ratio feedback control processing execution conditions are satisfied.
Proceed to 6 or below. In step 206, the cooling water temperature THW
Step 208 determines whether the throttle valve 14 is in a non-fully closed state; step 210 determines whether the downstream oxygen temperature sensor 37 is activated; Step 212 judges whether the downstream agricultural sensor (oxygen) is normal, and Step 214 judges whether the load on the engine 2 is equal to or higher than a predetermined load X1. It is assumed that the condition for executing air-fuel ratio feedback control in step 2 is satisfied, and step 21 is executed.
On the other hand, if a negative determination is made in any one step, it is assumed that the second air-fuel ratio feedback control execution condition is not satisfied, and the process proceeds to steps 230 and below.
第２の空燃比フィードバック制御実行条件成立時に実行
されるステップ２１６では、前回算出して記・憶されて
いるリッチスキップ量およびリーンスキップ量の両学習
値ＢＲ９Ｒ，ＢＲ５Ｌを各々リッチスキップｆｆ１Ｒ５
Ｒ−、リーンスキップｆｆ１Ｒ５Ｌに設定する処理が行
われる。続くステップ２１８では、下流側酸素）農産セ
ンサ３７の検出信号Ｖ２をＡ／Ｄ変換して読み込む処理
が行われる。次にステップ２２０に進み、下流側酸素澗
度センサ３７の検出信号Ｖ２が第２の比較電圧ＶＲ２（
例えば、０． ５５ ［Ｖ］ ）を上回るか否かを判定
し、肯定判断されると空燃比が過濃側（Ｒｉ ｃ ｈ）
であるとしてステップ２２２に、一方、否定判断される
と空燃比が希薄側（Ｌ ｅ ａ ｎ）であるとしてステ
ップ２２４に各々進む。空燃比が過温側（Ｒｉｃｈ）で
あるときに実行されるステップ２２２では、リッチスキ
ップ量Ｒ５Ｒの値からスキップ補正量ＫＲ５７ｔ−減算
すると共にリーンスキップ量Ｒ９Ｌの値にスキップ補正
量Ｋ ＲＳを加算した後、ステップ２２６に進む。一方
、空燃比が希薄側（Ｌｅａｎ）であるときに実行される
ステップ２２４では、リッチスキップ量Ｒ９Ｒの値にス
キップ補正量ＫＲ９を加算すると共に、リーンスキップ
量Ｒ９Ｌの値からスキップ補正量ＫＲ８を減算した後、
ステップ２２６に進む。ステップ２２６では、上記ステ
ップ２２２、もしくは、ステ・ンブ２２４で算出された
リッチスキップｆｆ１Ｒ５Ｒおよびりｉンスキップ量Ｒ
５Ｌの値を予め定められた下限１ｆｉａ以上、上限１直
す以下の値に制限する処理が行われる。続くステップ２
２８では、次回の処理に備えて、上記リッチスキップｆ
ｆ１Ｒ９Ｒおよびリーンスキップ°量Ｒ９Ｌの１直を、
リッチスキップ°量およびリーンスキップ量の両学習値
ＢＲ９Ｒ，ＢＲ５Ｌに各々設定すると共に、該学習値Ｂ
Ｒ９Ｒ。In step 216, which is executed when the second air-fuel ratio feedback control execution condition is satisfied, the learned values BR9R and BR5L of the rich skip amount and the lean skip amount, which were previously calculated and stored, are respectively set to the rich skip ff1R5.
A process of setting R- and lean skip ff1R5L is performed. In the following step 218, the detection signal V2 of the downstream side agricultural product sensor 37 is A/D converted and read. Next, the process proceeds to step 220, where the detection signal V2 of the downstream oxygen level sensor 37 is set to the second comparison voltage VR2 (
For example, 0. 55 [V]), and if it is affirmative, the air-fuel ratio is on the rich side (Rich).
On the other hand, if the determination is negative, the air-fuel ratio is determined to be on the lean side (Le a n), and the process proceeds to step 224. In step 222, which is executed when the air-fuel ratio is on the overtemperature side (Rich), the skip correction amount KR57t is subtracted from the value of the rich skip amount R5R, and the skip correction amount KRS is added to the value of the lean skip amount R9L. After that, the process proceeds to step 226. On the other hand, in step 224 executed when the air-fuel ratio is on the lean side (Lean), the skip correction amount KR9 is added to the value of the rich skip amount R9R, and the skip correction amount KR8 is subtracted from the value of the lean skip amount R9L. After that,
Proceed to step 226. In step 226, the rich skip ff1R5R and the rich skip amount R calculated in step 222 or step 224 are
Processing is performed to limit the value of 5L to a predetermined lower limit of 1fia or more and upper limit of 1fia or less. Next step 2
In 28, in preparation for the next process, the rich skip f
1st shift of f1R9R and lean skip degree amount R9L,
Both the rich skip amount and the lean skip amount are set to the learned values BR9R and BR5L, respectively, and the learned value B
R9R.
ＢＲ９ＬをＲＡＭ３ｃおよびバックアップＲＡＭ３ｄに
記憶した後、−旦、末弟２の空燃比フィードバック制御
処理を終了する。After storing BR9L in the RAM 3c and the backup RAM 3d, the air-fuel ratio feedback control process for the youngest brother 2 is ended.
一方、第２の空燃比フィードバック制御実行条件不成立
時に実行されるステ・ンプ２３０では、リーンスキップ
量Ｒ９Ｌの上限値Ｃを、第６図に示す、予めＲＯＭａｂ
内に記憶されているマツプに基づき、冷却水温度ＴＨＷ
に応じて算出する処理が行われる。同図に示すように、
リーンスキップ量Ｒ３Ｌの上限値Ｃは、冷却水温度ＴＨ
Ｗの上昇に伴って増加し、冷却水温度ＴＨＷがｄ ［’
Ｃ］に到ると、上限値Ｃは既述した上限値すに等しい
一定値すとなる。続くステップ２３２では、前回算出し
て記憶されているリッチスキップ量およびリーンスキッ
プ量の両学習値ＢＲ９Ｒ，ＢＲ５Ｌを各々リッチスキッ
プ量Ｒ９Ｒ、リーンスキップ量ＲＳＬに設定する処理が
行われる。次にステップ２３４に進み、リッチスキップ
量Ｒ９Ｒの値を予め定められた下限値ａ以上、上限値す
以下の値に制限すると共に、リーンスキップ量Ｒ９Ｌの
値を予め定められた下限値ａ以上、上記ステップ２３０
で算出した上限値Ｃ以下の量に制限する処理を行った後
、−旦、末弟２の空燃比フィードバック制御処理を終了
する。以後、末弟２の空燃比フィードバック制御処理は
所定時間毎に、上記ステップ２０２〜２３４を繰り返し
て実行する。On the other hand, in step 230, which is executed when the second air-fuel ratio feedback control execution condition is not satisfied, the upper limit value C of the lean skip amount R9L is set in advance in the ROMab as shown in FIG.
Cooling water temperature THW based on the map stored in
A calculation process is performed according to the . As shown in the figure,
The upper limit C of the lean skip amount R3L is the cooling water temperature TH.
It increases with the rise of W, and the cooling water temperature THW becomes d['
C], the upper limit value C becomes a constant value equal to the above-mentioned upper limit value. In the subsequent step 232, processing is performed to set the learned values BR9R and BR5L of the rich skip amount and the lean skip amount, which were previously calculated and stored, to the rich skip amount R9R and the lean skip amount RSL, respectively. Next, the process proceeds to step 234, in which the value of the rich skip amount R9R is limited to a value that is greater than or equal to a predetermined lower limit value a and less than or equal to an upper limit value, and the value of the lean skip amount R9L is limited to a value that is greater than or equal to a predetermined lower limit value a. Step 230 above
After carrying out the process of limiting the amount to be less than the upper limit value C calculated in , the air-fuel ratio feedback control process of the youngest brother 2 is ended on -1. Thereafter, the air-fuel ratio feedback control process for the youngest brother 2 repeats steps 202 to 234 at predetermined time intervals.
次に、燃料噴射制御処理を第７図に示すフローチャート
に基づいて説明する。本燃料噴射制御処理は、ＥＣＵ３
の起動後、所定クランク角度ｉ（例えば、３６０ ［°
ＣＡ］）に実行される。まず、ステップ３００では、既
述した各データを読み込む処理が行われる。続くステッ
プ３２０では、基本燃料噴射量ＴＡＵＯを、定数α、吸
入空気量Ｑおよび回転速度Ｎｅから、次式（１）のよう
に算出する処理が行われる。Next, the fuel injection control process will be explained based on the flowchart shown in FIG. This fuel injection control process is performed by the ECU3
After starting, a predetermined crank angle i (for example, 360 [°
CA]). First, in step 300, the process of reading each of the previously described data is performed. In the subsequent step 320, a process is performed to calculate the basic fuel injection amount TAUO from the constant α, the intake air amount Q, and the rotational speed Ne as shown in the following equation (1).
ＴＡＵＯ＝ ａ Ｘ Ｑ ／ Ｎｅ ・・
・ （１）続くステップ３３０では、暖機増量係数Ｆ
ＷＬを、冷却水温度ＴＨＷに応じて、ＲＯＭ３ｂに記憶
されている、第８図に示すマツプに従った補間計算によ
り算出する処理が行われる。０次に、ステ・ンブ３４０
に進み、実燃料噴射量ＴＡＵを次式（２）のように算出
する処理が行われる。但し、β。TAUO= a X Q / Ne...
(1) In the following step 330, the warm-up increase coefficient F
A process is performed to calculate WL according to the cooling water temperature THW by interpolation calculation according to the map shown in FIG. 8, which is stored in the ROM 3b. 0th order, Stembu 340
Then, the process of calculating the actual fuel injection amount TAU as shown in the following equation (2) is performed. However, β.
γは、他の運転状態パラメータに従って定まる補正係数
である。γ is a correction coefficient determined according to other operating state parameters.
ＴＡＵ ＝
ＴＡＵＯ・ＦＡＦ・ （ＦＷＬ＋β＋１）＋γ・・・
（２）
続くステップ３５０では、上記ステップ３４０で算出さ
れた実燃料噴射量ＴＡＵを、ダウンカウンタ３ｎにセッ
トすると共に、フリップフロップ回路３ｐをセットする
制御信号を出力して燃料噴射を開始させた後、−旦、本
燃料噴射制御処理を終了する。なお、既述したように、
実燃料噴射量ＴＡＵに相当する時間が経過すると、ダウ
ン力、ウンタ３ｎのキャリアウド信号により、フリップ
フロップ３ｐがリセットされて燃料噴射は終了する。TAU = TAUO・FAF・ (FWL+β+1)+γ...
(2) In the following step 350, the actual fuel injection amount TAU calculated in the above step 340 is set in the down counter 3n, and a control signal is output to set the flip-flop circuit 3p to start fuel injection. , -, this fuel injection control process ends. Furthermore, as mentioned above,
When the time corresponding to the actual fuel injection amount TAU has elapsed, the flip-flop 3p is reset by the down force and the carrier signal from the counter 3n, and the fuel injection ends.
以後、本燃料噴旧制御処理は所定クランク角度毎に、上
記ステップ３００〜３５０を繰り返して実行する。Thereafter, this fuel injection control process repeats steps 300 to 350 at every predetermined crank angle.
なお本実施例において、エンジン２が内燃機関Ｍ１に、
触媒コンバータ１９が三元触媒Ｍ２に、上流側酸素濃度
センサ３６が上流側空燃比検出手段Ｍ３に、下流側酸素
濃度センサ３７が下流側空燃比検出手段Ｍ４に、燃料噴
射弁２５が空燃比調節手段Ｍ５に、水温センサ３５が運
転状態検出手段Ｍ６に、各々該当する。また、ＥＣＵ３
および該ＥＣＵ３の実行する処理のうちステップ（２０
４〜２１４）が判定手段Ｍ７として、ステップ（２１８
〜２２４）が制御定数算出手段Ｍ８として、ステップ（
２２６，２２８）が学習手段Ｍ９として、ステップ（１
０２〜１６４．３００〜３５０）が空燃比フィードバッ
ク制御手段ＭＩＯとして、ステップ（２３０〜２３４）
が補正手段Ｍｌｌとして、各々機能する。Note that in this embodiment, the engine 2 is the internal combustion engine M1,
The catalytic converter 19 serves as a three-way catalyst M2, the upstream oxygen concentration sensor 36 serves as an upstream air-fuel ratio detection means M3, the downstream oxygen concentration sensor 37 serves as a downstream air-fuel ratio detection means M4, and the fuel injection valve 25 serves as an air-fuel ratio controller. The water temperature sensor 35 corresponds to the means M5 and the operating state detecting means M6, respectively. Also, ECU3
and step (20) of the processing executed by the ECU 3.
4 to 214) as the determination means M7, and step (218
~224) as the control constant calculation means M8, step (
226, 228) as the learning means M9, step (1
02-164.300-350) as the air-fuel ratio feedback control means MIO, steps (230-234)
respectively function as correction means Mll.
以上説明したように本実施例によれば、暖機過程で、第
１の空燃比フィードバック制御処理のみを実行し、第２
の空燃比フィードパ・ンク制御処理を中止したときでも
、空燃比の希薄側（Ｌ ｅ ａ ｎ）への大きな移行を
防止し、ドライバビリティを改善できる。As explained above, according to this embodiment, only the first air-fuel ratio feedback control process is executed during the warm-up process, and the second
Even when the air-fuel ratio feed puncture control process is stopped, it is possible to prevent a large shift of the air-fuel ratio to the lean side (L e an ) and improve drivability.
また、第２の空燃比フィードバック制御処理中止時に、
リーンスキップ量Ｒ９Ｌの上限値Ｃを、）令却水温度Ｔ
ＨＷに応じて、第２の空燃比フィードバック制御処理実
行時の上限値すまで、徐々に増加補正して適切な値に制
限するので、暖機初期時等、冷却水温度ＴＨＷが低い場
合の上記リーンスキップ量Ｒ９Ｌの過大な増量の抑止に
より、ドライバビリティを向上できると共に、暖機完了
直前では、上記リーンスキップ量Ｒ９Ｌを適切な値に設
定して空燃比の過温側（Ｒｉｃｈ）への大きな変動を防
止し、排気中の有害成分排出量の増加を招くことなく、
空燃比補正係数ＦＡＦによる空燃比補正能力を充分発揮
できる。Furthermore, when the second air-fuel ratio feedback control process is stopped,
The upper limit C of the lean skip amount R9L is determined by the cooling water temperature T
According to the HW, the increase is gradually corrected until the upper limit value is reached when the second air-fuel ratio feedback control process is executed, and the limit is set to an appropriate value. By preventing an excessive increase in the lean skip amount R9L, drivability can be improved, and just before the warm-up is completed, the lean skip amount R9L is set to an appropriate value to prevent a large increase in the air-fuel ratio to the overtemperature side (Rich). This prevents fluctuations and increases the amount of harmful component emissions in exhaust gas.
The air-fuel ratio correction ability by the air-fuel ratio correction coefficient FAF can be fully demonstrated.
さらに、例えば、フューエルカット、２次空気導入等の
解除後、三元触媒の酸素ストレージ効果による空燃比の
過補正防止のために、第１の空燃比フィードバック制御
処理のみを実行し、第２の空燃比フィードバック制ｉ卸
処理を停止しているときでも、冷却水温度ＴＨＷの上昇
に応じてリーンスキップ量Ｒ９Ｌの上限ｆｉ ｃを増加
させると、空燃比の制御中心の過温側（Ｒｉｃｈ）への
大きな変動を防止できる。Further, for example, after canceling fuel cut, secondary air introduction, etc., only the first air-fuel ratio feedback control process is executed and the second Even when the air-fuel ratio feedback control i wholesale process is stopped, if the upper limit fi c of the lean skip amount R9L is increased in accordance with the increase in the cooling water temperature THW, the air-fuel ratio control center will shift to the overtemperature side (Rich). can prevent large fluctuations in
また、比較的短い周期で変動する上流側酸素濃度センサ
３６の検出信号ｖ１に基づく第１の空燃比フィードバッ
ク制御処理を４［ｍ５ｅｃｌ毎に、一方、比較的長い周
期で変動する下流側酸素温度センサ３７の検出信号Ｖ２
に基づく第２の空燃比フィードバック利潤処理を５１２
［ｍ５ｅｃｌ毎に実行するので、制御の応答性・追従性
を高水準に補償できる。Further, the first air-fuel ratio feedback control process based on the detection signal v1 of the upstream oxygen concentration sensor 36 that fluctuates in a relatively short cycle is performed every 4 [m5ecl], while the downstream oxygen temperature sensor that fluctuates in a relatively long cycle 37 detection signal V2
A second air-fuel ratio feedback profit process based on 512
[Since it is executed every m5ecl, control responsiveness and followability can be compensated to a high level.
なお、第１の空燃比フィードバック補正係数ＦＡＦと第
２の空燃比フィードバック補正係数ＦＡＦ２とを併用す
る構成では、第２の空燃比フィードバック補正係数ＦＡ
Ｆ２の補正量を、上述した実施例と同様に、冷却水温度
ＴＨＷに応じて増加する上限値により制限しながら増減
補正すると、同様の効果を秦する。Note that in a configuration in which the first air-fuel ratio feedback correction coefficient FAF and the second air-fuel ratio feedback correction coefficient FAF2 are used together, the second air-fuel ratio feedback correction coefficient FA
Similar effects can be obtained by increasing or decreasing the correction amount of F2 while limiting it by an upper limit value that increases according to the cooling water temperature THW, as in the above-described embodiment.
また、スキップ量Ｒ９Ｒ，Ｒ９Ｌ、遅延時間ＴＤＬ、Ｔ
ＤＲ１積分定数ＫＩＬ、ＫＩＲ１第１の比較電圧ＶＲＩ
の内、複数の制御定数の補正量の上限値、もしくは、下
限値を冷却水温度ＴＨＷに応じて同時に変更するよう構
成すると、制御精度および応答性・追従性をより一層向
上できる。Also, skip amounts R9R, R9L, delay times TDL, T
DR1 integral constant KIL, KIR1 first comparison voltage VRI
If the upper limit value or the lower limit value of the correction amount of a plurality of control constants is changed simultaneously according to the cooling water temperature THW, control accuracy, responsiveness, and followability can be further improved.
さらに、スキップ量Ｒ５Ｒ，Ｒ９Ｌ、遅延時間ＴＤＬ、
ＴＤＲ５積分定数ＫＩＬ、ＫＩＲ，第１の比較電圧ＶＲ
Ｉの内、過温側（Ｒｉｃｈ）、もしくは、希薄側（Ｌｅ
ａｎ）の何れか一方を一定値とし、他方だけを下流側酸
素濃度センサ３７の検出信号■２に基づいて増減補正す
る構成においても、該増減補正する制御定数の上限値や
下限値を冷却水温度ＴＨＷの増加に応じて変更しても良
−い。Furthermore, skip amounts R5R, R9L, delay time TDL,
TDR5 integral constants KIL, KIR, first comparison voltage VR
I, the overtemperature side (Rich) or the lean side (Le
Even in a configuration in which either one of an) is set to a constant value and only the other is increased or decreased based on the detection signal (2) of the downstream oxygen concentration sensor 37, the upper or lower limit value of the control constant to be increased or decreased is set to the cooling water. It may be changed according to an increase in temperature THW.
また、上述した実施例では、水温センサ３５の検出した
冷却水温度ＴＨＷによりエンジン２の暖機状態を検出す
るよう構成したが、例えば、シリンダブロ・ンク４ａの
温度を検出する機関温度センサ、エンジン２のオイルの
温度を検出する油温センサ、エンジン２の始動時からの
経過時間を計測するタイマ等の検出結果に基づいて、エ
ンジン２の暖機状態を検出するよう構成しても良い。Further, in the above-described embodiment, the warm-up state of the engine 2 is detected based on the cooling water temperature THW detected by the water temperature sensor 35. The warm-up state of the engine 2 may be detected based on the detection results of an oil temperature sensor that detects the temperature of the oil of the engine 2, a timer that measures the elapsed time from the start of the engine 2, or the like.
さらに、上述した実施例では、エアフロメータ３１の検
出する吸入空気量Ｑおよび回転角センサ３９の検出する
回転速度Ｎｅに基づいて燃料噴射量ＴＡＵを決定するよ
う構成したが、例えは、カルマン渦センサ、ポットワイ
ヤセンサ等により吸入空気量Ｑを計測しても良いし、吸
気管圧力ＰＭと回転速度Ｎｅと、あるいは、スロットル
バルブ開度ＴＡと回転速度Ｎｅとに基づいて燃料噴射量
ＴＡＵを算出する構成であっても良い。Further, in the embodiment described above, the fuel injection amount TAU is determined based on the intake air amount Q detected by the air flow meter 31 and the rotational speed Ne detected by the rotation angle sensor 39. The intake air amount Q may be measured using a pot wire sensor or the like, or the fuel injection amount TAU may be calculated based on the intake pipe pressure PM and the rotational speed Ne, or the throttle valve opening TA and the rotational speed Ne. It may be a configuration.
また、上述の実施例では、酸素濃度センサ３６゜３７を
使用したが、例えば、−酸化炭素ＣＯを検出するガスセ
ンサ、あるいは、所謂、リーンミクスチャセンサ等を使
用しても良い。Further, in the above-described embodiment, the oxygen concentration sensors 36 and 37 were used, but for example, a gas sensor that detects -carbon oxide CO or a so-called lean mixture sensor may also be used.
さらに、上述の実施例では、燃料噴射弁２５により燃料
噴射量を制御するエンジンの空燃比制御装置１について
説明した。しかし、例えは°、気化器を備えたエンジン
であって、エアコントロールバルブ（ＥＡＣＶ）により
吸入空気量を制御するエンジン、ブリードエアコントロ
ールバルブにより気化器のブリードエア量を調節してメ
イン系通路およびスロー系通路への大気の導入により空
燃比を制御するエンジン、排気系に供給される２次空気
の量を調節するエンジン等にも適用できる。Furthermore, in the above-described embodiment, the engine air-fuel ratio control device 1 that controls the fuel injection amount using the fuel injection valve 25 has been described. However, for example, an engine is equipped with a carburetor, and the amount of intake air is controlled by an air control valve (EACV). It can also be applied to engines that control the air-fuel ratio by introducing atmospheric air into the slow system passage, engines that adjust the amount of secondary air supplied to the exhaust system, etc.
このように、気化器を備えたエンジンでは、基本燃料噴
射量が気化器の特性から定まり、所望の空燃比を実現す
る供給空気量を演算により算出して空燃比制御を行なう
のである。In this way, in an engine equipped with a carburetor, the basic fuel injection amount is determined from the characteristics of the carburetor, and the air-fuel ratio is controlled by calculating the amount of supplied air that achieves a desired air-fuel ratio.
以上本発明の実施例について説明したが、本発明はこの
ような実施例に同等限定されるものではなく、本発明の
要旨を逸脱しない範囲内において種々なる態様で実施し
得ることは勿論である。Although the embodiments of the present invention have been described above, the present invention is not equally limited to these embodiments, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. .
発明の効果
以上詳記したように本発明の内燃機関の空燃比制御装置
は、暖機完了以前で、上流側空燃比に基づく空燃比フィ
ードバック制御のみを実行し、下流側空燃比に応じて空
燃比フィードパ・ンク制御定数を算出しないときは、学
習記憶されている空燃比フィードバック制御定数の制限
幅を暖機過程の進行に伴って拡大し、過大な空燃比フィ
ードバック制御定数に起因する暖機中の空燃比の希薄側
への大きな変動を抑制するよう構成されている。このた
め、暖ａ！過程で、上流側空燃比に応じた空燃比フィー
ドバック制御のみを実行し、下流側空燃比に応じた空燃
比フィードバック制ｉＢ定数の算出を中止するときでも
、空燃比を適正に補正でき、特に、空燃比の希薄側（Ｌ
ｅ ａ ｎ）への大きな移行の防止により、運転性能
（ドライバビリティ）を改善できるという優れた効果を
奏する。Effects of the Invention As detailed above, the air-fuel ratio control device for an internal combustion engine of the present invention executes only the air-fuel ratio feedback control based on the upstream air-fuel ratio before the completion of warm-up, and controls the air-fuel ratio according to the downstream air-fuel ratio. When the fuel ratio feed pump/puncture control constant is not calculated, the limit range of the air-fuel ratio feedback control constant that has been learned and stored is expanded as the warm-up process progresses, and the limit width of the air-fuel ratio feedback control constant that is learned and stored is expanded during warm-up due to an excessive air-fuel ratio feedback control constant. The air-fuel ratio is configured to suppress large fluctuations toward the lean side. For this reason, warm a! In the process, even when executing only the air-fuel ratio feedback control according to the upstream air-fuel ratio and canceling the calculation of the air-fuel ratio feedback control iB constant according to the downstream air-fuel ratio, the air-fuel ratio can be appropriately corrected, and in particular, The lean side of the air-fuel ratio (L
By preventing a large shift to e a n), there is an excellent effect that driving performance (drivability) can be improved.
また、空燃比フィードバック制御定数を８ｉＵ４ｆｆｌ
状態に応じた適切な値に制限するので、特に、暖機初期
時等、冷却水温度が低い場合にも、上記空燃比フィード
バック制御定数を最適値に設定でき、排気特性の悪化を
招くことなく、空燃比補正係数による空燃比補正能力を
高水準に保持できる。Also, the air-fuel ratio feedback control constant is 8iU4ffl
Since it is limited to an appropriate value depending on the condition, the air-fuel ratio feedback control constant can be set to the optimal value even when the cooling water temperature is low, such as during the initial warm-up period, without causing deterioration of exhaust characteristics. , the air-fuel ratio correction ability using the air-fuel ratio correction coefficient can be maintained at a high level.
第１図は本発明の内容を概念的に例示した基本的構成図
、第２図は本発明第一実施例のシステム構成図、第３図
（１）、 （２）は同じくその制御を示すフローチャ
ート、第４図は同じくその制御の様子を示すタイミング
チャート、第５図（１）。
（２）は同じくその制ｉ卸を示すフローチャーＩ・、第
６図は同じくそのマツプを示すグラフ、第７図は同じく
その制御を示すフローチャート、第８図は同じくそのマ
ツプを示すグラフ、第９図は従来技術の排気特性を示す
グラフ、第１０図は従来技術の制御の様子を示すタイミ
ングチャートである。
Ｍｌ ・・・ 内燃機関
Ｍ２ ・・・ 三元触媒
Ｍ３ ・・・ 上流側空燃比検出手段
Ｍ４ ・・・ 下流側空燃比検出手段
Ｍ５ ・・・ 空燃比調節手段
Ｍ６ ・・・ 運転状態検出手段
Ｍｌ ・・・ 判定手段
Ｍ８ ・・・ 制御定数算出手段
Ｍ９ ・・・ 学習手段
ＩＶＩ １０ ・・・ 空燃比フィードバック制ｉ卸
手段Ｍｌｌ ・・・ 補正手段
１ ・・・ エンジンの空燃比制御装置２ ・・・ エ
ンジン
３ ・・・ 電子制御装置（ＥＣＵ）
３ａ ・・・ ＣＰＵ
１９ ・・・ 触媒コンバータ
２５ ・・・ 燃料噴射弁
３５ ・・・ 水温センサ
３６ ・・・ 上流側酸素）震度センサ３７ ・・・
下流側酸素濃度センサFig. 1 is a basic configuration diagram conceptually illustrating the content of the present invention, Fig. 2 is a system configuration diagram of the first embodiment of the invention, and Figs. 3 (1) and (2) similarly show its control. The flowchart in FIG. 4 is also a timing chart showing the state of the control, FIG. 5(1). (2) is a flowchart showing the control, FIG. 6 is a graph showing the map, FIG. 7 is a flowchart showing the control, and FIG. 8 is a graph showing the map. FIG. 9 is a graph showing the exhaust characteristics of the prior art, and FIG. 10 is a timing chart showing the state of control in the prior art. Ml... Internal combustion engine M2... Three-way catalyst M3... Upstream air-fuel ratio detection means M4... Downstream air-fuel ratio detection means M5... Air-fuel ratio adjustment means M6... Operating state detection means Ml ... Judgment means M8 ... Control constant calculation means M9 ... Learning means IVI 10 ... Air-fuel ratio feedback control means Mll ... Correction means 1 ... Engine air-fuel ratio control device 2 ...・ Engine 3 ... Electronic control unit (ECU) 3a ... CPU 19 ... Catalytic converter 25 ... Fuel injection valve 35 ... Water temperature sensor 36 ... Upstream oxygen) Seismic intensity sensor 37 ...
Downstream oxygen concentration sensor
Claims (1)
元触媒と、 該三元触媒の上流側の排気通路に配設され、排気中の特
定成分濃度を検出する上流側空燃比検出手段と、 上記三元触媒の下流側の排気通路に配設され、排気中の
特定成分濃度を検出する下流側空燃比検出手段と、 外部から指令される制御量に従って、上記内燃機関の空
燃比を調節する空燃比調節手段と、上記内燃機関の、少
なくとも暖機状態を含む運転状態を検出する運転状態検
出手段と、該運転状態検出手段の検出した運転状態に基
づいて、上記内燃機関の運転状態が、上記下流側空燃比
検出手段の検出結果に基づく空燃比フィードバック制御
定数算出可能な算出可能運転状態にあるか否かを判定す
る判定手段と、 該判定手段により算出可能運転状態にあると判定された
ときに、上記下流側空燃比検出手段の検出結果に応じて
、空燃比フィードバック制御定数を算出する制御定数算
出手段と、該制御定数算出手段の算出した空燃比フィー
ドバック制御定数を所定制限幅以内に制限し、更新記憶
する学習手段と、 該学習手段の記憶している空燃比フィードバック制御定
数および前記上流側空燃比検出手段の検出結果に応じて
決定した制御量を上記空燃比調節手段に指令する空燃比
フィードバック制御手段と、を具備した内燃機関の空燃
比制御装置であって、さらに、上記内燃機関の暖機完了
以前で、上記判定手段により算出可能運転状態にないと
判定されたときは、上記学習手段の記憶している空燃比
フィードバック制御定数の所定制限幅を、上記運転状態
検出手段の検出した暖機状態の暖機完了への進行過程に
応じて、上記所定制限幅より狭い初期制限幅から該所定
制限幅までの範囲で増加補正する補正手段を備えたこと
を特徴とする内燃機関の空燃比制御装置。[Scope of Claims] 1. A three-way catalyst installed in the exhaust passage of an internal combustion engine to purify exhaust gas; and a three-way catalyst installed in the exhaust passage upstream of the three-way catalyst to detect the concentration of a specific component in the exhaust gas. an upstream air-fuel ratio detection means; a downstream air-fuel ratio detection means disposed in the exhaust passage downstream of the three-way catalyst to detect the concentration of a specific component in the exhaust; an air-fuel ratio adjusting means for adjusting the air-fuel ratio of the internal combustion engine; an operating state detecting means for detecting the operating state of the internal combustion engine, including at least a warm-up state; and based on the operating state detected by the operating state detecting means, determining means for determining whether or not the operating state of the internal combustion engine is in a computable operating state in which an air-fuel ratio feedback control constant can be calculated based on the detection result of the downstream air-fuel ratio detecting means; control constant calculation means for calculating an air-fuel ratio feedback control constant according to the detection result of the downstream side air-fuel ratio detection means when it is determined that the operating state is in operation; and the air-fuel ratio feedback calculated by the control constant calculation means. learning means for limiting and updating a control constant within a predetermined limit width; and a control amount determined according to an air-fuel ratio feedback control constant stored in the learning means and a detection result of the upstream air-fuel ratio detecting means. An air-fuel ratio control device for an internal combustion engine, comprising an air-fuel ratio feedback control means for instructing the air-fuel ratio adjusting means, further comprising: an air-fuel ratio control device for an internal combustion engine, wherein the internal combustion engine is brought into a computable operating state by the determination means before the warm-up of the internal combustion engine is completed; When it is determined that there is no such thing, the predetermined limit width of the air-fuel ratio feedback control constant stored in the learning means is set according to the progress of the warm-up state detected by the operating state detecting means to the completion of warm-up. An air-fuel ratio control device for an internal combustion engine, comprising a correction means that performs an incremental correction in a range from an initial limit width narrower than the predetermined limit width to the predetermined limit width.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5903488A JP2600772B2 (en) | 1988-03-11 | 1988-03-11 | Air-fuel ratio control device for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5903488A JP2600772B2 (en) | 1988-03-11 | 1988-03-11 | Air-fuel ratio control device for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01232142A true JPH01232142A (en) | 1989-09-18 |
| JP2600772B2 JP2600772B2 (en) | 1997-04-16 |
Family
ID=13101604
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5903488A Expired - Fee Related JP2600772B2 (en) | 1988-03-11 | 1988-03-11 | Air-fuel ratio control device for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2600772B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05180039A (en) * | 1991-12-25 | 1993-07-20 | Mitsubishi Motors Corp | Air-fuel ratio control device for engine |
-
1988
- 1988-03-11 JP JP5903488A patent/JP2600772B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05180039A (en) * | 1991-12-25 | 1993-07-20 | Mitsubishi Motors Corp | Air-fuel ratio control device for engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2600772B2 (en) | 1997-04-16 |
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