JPH0325623B2 - - Google Patents
Info
- Publication number
- JPH0325623B2 JPH0325623B2 JP56138756A JP13875681A JPH0325623B2 JP H0325623 B2 JPH0325623 B2 JP H0325623B2 JP 56138756 A JP56138756 A JP 56138756A JP 13875681 A JP13875681 A JP 13875681A JP H0325623 B2 JPH0325623 B2 JP H0325623B2
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- feedback control
- feedback
- oxygen concentration
- 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 claims description 66
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 46
- 239000001301 oxygen Substances 0.000 claims description 46
- 229910052760 oxygen Inorganic materials 0.000 claims description 46
- 239000007789 gas Substances 0.000 claims description 18
- 239000003054 catalyst Substances 0.000 claims description 15
- 238000002485 combustion reaction Methods 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 230000010354 integration Effects 0.000 claims description 6
- 230000004043 responsiveness Effects 0.000 description 18
- 230000001934 delay Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000007562 laser obscuration time method Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1477—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation circuit or part of it,(e.g. comparator, PI regulator, output)
- F02D41/1482—Integrator, i.e. variable slope
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Description
本発明は、内燃機関の空燃比制御方法に係り、
特に、三元触媒を用いて排気ガス浄化対策が施さ
れた自動車用内燃機関に用いるに好適な、触媒流
入ガス中の残存酸素濃度を感知する酸素濃度セン
サと、混合気或いは触媒流入ガスの空燃比を制御
する空燃比制御アクチユエータとを用い、前記酸
素濃度センサの出力に対して積分を含む処理を施
すことによつて得られる帰還制御信号により前記
空燃比制御アクチユエータを帰還制御して、混合
気或いは触媒流入ガスの空燃比を所望空燃比とす
る内燃機関の空燃比制御方法の改良に関する。
The present invention relates to an air-fuel ratio control method for an internal combustion engine,
In particular, we have developed an oxygen concentration sensor that detects the residual oxygen concentration in the gas flowing into the catalyst, which is suitable for use in automobile internal combustion engines that use a three-way catalyst to purify exhaust gas, and an oxygen concentration sensor that detects the residual oxygen concentration in the gas flowing into the catalyst. Using an air-fuel ratio control actuator that controls the fuel ratio, the air-fuel ratio control actuator is feedback-controlled by a feedback control signal obtained by performing processing including integration on the output of the oxygen concentration sensor, and the air-fuel ratio control actuator is feedback-controlled. Alternatively, the present invention relates to an improvement in an air-fuel ratio control method for an internal combustion engine for adjusting the air-fuel ratio of catalyst inflow gas to a desired air-fuel ratio.
内燃機関、特に、厳しい排気ガス浄化対策が要
求される自動車用内燃機関においては、近年、精
密な空燃比制御を行なうことが必要となつてお
り、例えば、触媒流入ガスの残存酸素濃度を感知
する酸素濃度センサと、混合気或いは触媒流入ガ
スの空燃比を制御する空燃比制御アクチユエータ
とを備え、前記酸素濃度センサの出力に対して積
分を含む処理を施すことによつて得られる帰還制
御信号により前記空燃比制御アクチユエータを帰
還制御して、触媒流入ガス中の残存酸素濃度を、
理論空燃比の混合気を燃焼させた場合の残存酸素
濃度と等しくするようにしたものが実用化されて
いる。
このような空燃比制御によれば、エンジン運転
状態の変化に拘らず、良好な排気ガス浄化性能を
得ることができるという特徴を有する。
In recent years, it has become necessary to perform precise air-fuel ratio control in internal combustion engines, especially automotive internal combustion engines that require strict exhaust gas purification measures.For example, it is necessary to perform precise air-fuel ratio control. It is equipped with an oxygen concentration sensor and an air-fuel ratio control actuator that controls the air-fuel ratio of the air-fuel mixture or the gas flowing into the catalyst, and a feedback control signal obtained by performing processing including integration on the output of the oxygen concentration sensor. The air-fuel ratio control actuator is feedback-controlled to control the residual oxygen concentration in the catalyst inflow gas.
A device in which the concentration of residual oxygen is made equal to the concentration of residual oxygen when a mixture with a stoichiometric air-fuel ratio is combusted has been put into practical use. Such air-fuel ratio control is characterized in that good exhaust gas purification performance can be obtained regardless of changes in engine operating conditions.
しかしながら、一般にアイドル状態は、吸入空
気量が少なく、酸素濃度センサの応答性が悪くな
つているため、従来の空燃比制御においては、特
に、減速状態からアイドル状態に移つた時のよう
に、帰還停止状態からアイドル制御を開始する時
に、アイドル状態の積分定数では小さ過ぎて迅速
な空燃比帰還制御を行なうことができず、制御遅
れを発生したり、或いは、逆に制御過補償を発生
することがあつた。
本発明は、前記従来の欠点を解消するべくなさ
れたもので、帰還停止状態からアイドル状態近傍
の帰還制御を行うべき状態に移行する帰還制御の
再開時に、制御遅れ或いは制御過補償を解消で
き、従つて、制御性を向上できる内燃機関の空燃
比制御方法を提供することを目的とする。
However, in general, when the idle state is low, the amount of intake air is small and the responsiveness of the oxygen concentration sensor is poor. When starting idle control from a stopped state, the integral constant in the idle state is too small to perform quick air-fuel ratio feedback control, causing control delays or conversely, control overcompensation. It was hot. The present invention has been made to eliminate the above-mentioned conventional drawbacks, and is capable of eliminating control delay or control overcompensation when restarting feedback control that transitions from a feedback stop state to a state near an idle state where feedback control should be performed. Therefore, it is an object of the present invention to provide an air-fuel ratio control method for an internal combustion engine that can improve controllability.
本発明は、触媒流入ガス中の残存酸素濃度を感
知する酸素濃度センサと、混合気或いは触媒流入
ガスの空燃比を制御する空燃比制御アクチユエー
タとを用い、前記酸素濃度センサの出力に対して
積分を含む処理を施すことによつて得られる帰還
制御信号により前記空燃比制御アクチユエータを
帰還制御して、混合気或いは触媒流入ガスの空燃
比を所望空燃比とし、又、必要に応じて該帰還制
御を停止する内燃機関の空燃比制御方法におい
て、前記帰還制御の停止状態から、アイドル状態
近傍の帰還制御を行うべき状態に移行する帰還制
御の再開時、酸素濃度センサの出力が所定サイク
ル変化するまで、前記アイドル状態近傍の前記帰
還制御に用いられる積分定数より大きい積分定数
を用いて前記酸素濃度センサの出力を処理するこ
とによつて得られる帰還制御信号により、前記空
燃比アクチユエータを帰還制御するようにして、
前記目的を達成したものである。
The present invention uses an oxygen concentration sensor that senses the residual oxygen concentration in the catalyst inflow gas and an air-fuel ratio control actuator that controls the air-fuel ratio of the air-fuel mixture or the catalyst inflow gas, and integrates the output of the oxygen concentration sensor. The air-fuel ratio control actuator is feedback-controlled by a feedback control signal obtained by performing processing including In the air-fuel ratio control method for an internal combustion engine that stops the feedback control, when the feedback control is restarted from the stopped state of the feedback control to a state where the feedback control should be performed near the idle state, until the output of the oxygen concentration sensor changes for a predetermined cycle. , the air-fuel ratio actuator is feedback-controlled by a feedback control signal obtained by processing the output of the oxygen concentration sensor using an integral constant larger than the integral constant used for the feedback control near the idle state. and
The above objective has been achieved.
従来から、帰還制御において、積分処理を含む
処理が施された帰還制御信号が用いられている。
このように積分処理を帰還制御信号に施すのは、
センサから出力される信号に含まれてしまつてい
る比較的周期の短い（周波数の高い）ノイズ（電
気的なものや、機構的なもの等）を効果的に除去
するためである。
しかしながら、このような積分処理を施した帰
還制御信号を用いた場合には、帰還制御の応答性
が低下してしまうという問題がある。又、帰還制
御の再開時は、目標値からの偏差が比較的大き
く、この帰還制御の応答性の低下の問題は大き
い。
特に、アイドル状態近傍或いはアイドル状態近
傍に移行するときにおいては、前述のように酸素
濃度センサの応答性が悪くなつており、このよう
なときに帰還制御を再開すると、この帰還制御の
帰還制御信号に積分処理を施している場合には、
応答性の低下が著しくなつてしまう。
このため、本発明では、帰還制御の停止状態か
ら、帰還制御を行うアイドル状態に移行する際、
即ち、帰還制御開始時に、酸素濃度センサの出力
が所定サイクル変化するまで（ほぼ必要十分な期
間）、アイドル状態の帰還制御に用いられる積分
定数より大きい積分定数を用いて積分処理を行う
ことにより、酸素濃度センサの応答性低下の問題
をも解決して、空燃比制御の応答性の向上を図つ
ている。
ここで、本発明で、帰還制御再開時に、アイド
ル状態の帰還制御に用いられる積分定数より大き
い積分定数を用いる期間を、単に所定時間（一定
時間）とせず、酸素濃度センサの出力が所定サイ
クル変化するまでの期間としているのは、制御さ
れる空燃比が実際に目標値に追従できるようにな
つた時点で、大きくなつている積分定数を、アイ
ドル状態の帰還制御に用いられる小さな積分定数
に、速やかに戻すためである（ほぼ必要十分な期
間）。
もし、このアイドル状態の帰還制御に用いられ
る積分定数より大きい積分定数を用いる期間を、
単に所定時間（一定時間）とすると、帰還制御が
実際に追従できるようになつたか否かはわからな
い。即ち、空燃比が目標値に追従していないのに
積分定数が小さい値に戻されたり（所定時間が短
い）、空燃比が目標値に既に追従してしまつてい
るのに積分定数が小さい値に戻されなかつたり
（所定時間が長い）という問題が生じてしまう。
なぜなら、帰還制御が収束するまでの時間は、
酸素濃度センサの出力の応答性や、積分処理を含
む帰還制御の応答性に依存しているが、これらの
応答性は常に一定ではないために、この収束する
までの時間も一定時間ではないからである。例え
ば、酸素濃度センサの出力の応答性は、各酸素濃
度センサ間の個体差があるだけでなく、同一の酸
素濃度センサであつても、検出時の周囲温度や酸
素濃度等にも依存して変化してしまうからである
（応答性の変化）。又、積分処理を含む帰還制御の
応答性も、再開時の制御される空燃比の目標値か
らの偏差等に依存して変化してしまうからである
（応答性の変化）。
一方、本発明では、帰還制御が収束するまでの
期間を、酸素濃度センサの出力が所定サイクル変
化するまでの期間としている。酸素濃度センサの
出力が所定サイクル変化したということは、空燃
比を制御するための制御系全体が、実際に空燃比
の目標値に追従し始めた、あるいは追従したとい
うことである。従つて、前述のような、酸素濃度
センサの出力の応答性に変化があつたり、積分処
理を含む帰還制御の応答性に変化があつても、空
燃比を制御するための制御系全体が実際に空燃比
の目標値に追従し始めた、あるいは追従した時点
で、時間的ずれを生じることなく積分定数を小さ
に値に戻すことができる。
従つて、本発明によれば、積分定数が大きくな
るのはほぼ必要十分な期間（即ち、帰還制御の再
開時の比較的大きな目標値からの偏差を応答性よ
く解消でき、且つ、ハンチングが発生してしまう
よりは短い期間）であり、通常は大きくない積分
定数が用いられるので、空燃比制御の安定度を低
下させることもなく、ハンチング等をも防止する
ことができる。
なお、本発明の、帰還制御の停止状態から、帰
還制御を行うアイドル状態近傍に移行する帰還制
御再開時とは、減速状態からアイドル状態への移
行時等に限定したものではない。これは、継続的
にアイドル状態乃至はアイドル状態近傍であつて
も、帰還制御が停止したり、再開するものである
からである。即ち、この帰還制御の停止は、帰還
制御が好ましくないときに行われるものであつ
て、アイドル状態であるか否かや或いはスロツト
ル弁の状態等には、単独に関係するものではない
からである（エンジン回転数等にも関係してい
る）。
Conventionally, in feedback control, a feedback control signal that has been subjected to processing including integration processing has been used.
Applying integral processing to the feedback control signal in this way is
This is to effectively remove relatively short period (high frequency) noise (electrical, mechanical, etc.) that is included in the signal output from the sensor. However, when a feedback control signal subjected to such integral processing is used, there is a problem in that the responsiveness of the feedback control decreases. Furthermore, when the feedback control is restarted, the deviation from the target value is relatively large, and the problem of decreased responsiveness of the feedback control is significant. In particular, as described above, the responsiveness of the oxygen concentration sensor deteriorates near the idle state or when transitioning to the vicinity of the idle state, and if feedback control is restarted at such times, the feedback control signal of this feedback control If you apply integral processing to
Responsiveness deteriorates significantly. Therefore, in the present invention, when transitioning from a stopped state of feedback control to an idle state in which feedback control is performed,
That is, at the start of feedback control, by performing integration processing using an integral constant larger than the integral constant used for feedback control in the idle state until the output of the oxygen concentration sensor changes for a predetermined cycle (almost a necessary and sufficient period), This also solves the problem of decreased responsiveness of the oxygen concentration sensor and improves the responsiveness of air-fuel ratio control. Here, in the present invention, when restarting feedback control, the period in which an integral constant larger than the integral constant used for feedback control in the idle state is not simply set to a predetermined time (fixed time), but the output of the oxygen concentration sensor changes by a predetermined cycle. The reason for this is that when the controlled air-fuel ratio can actually follow the target value, the increasing integral constant is changed to a smaller integral constant used for feedback control in the idle state. This is to quickly return the situation (almost for the necessary and sufficient period). If the period using an integral constant larger than the integral constant used for feedback control in this idle state is
If it is simply a predetermined time (constant time), it is not known whether the feedback control can actually follow up. In other words, the integral constant is returned to a small value even though the air-fuel ratio does not follow the target value (the predetermined time is short), or the integral constant is returned to a small value even though the air-fuel ratio has already followed the target value. A problem arises in that the data is not returned to the original state (the predetermined time is long). This is because the time it takes for feedback control to converge is
It depends on the responsiveness of the output of the oxygen concentration sensor and the responsiveness of feedback control including integral processing, but since these responsivenesses are not always constant, the time it takes for this to converge is also not a constant time. It is. For example, the responsiveness of the output of an oxygen concentration sensor not only has individual differences between each oxygen concentration sensor, but also depends on the ambient temperature, oxygen concentration, etc. at the time of detection, even for the same oxygen concentration sensor. This is because it changes (change in responsiveness). Further, the responsiveness of the feedback control including the integral processing also changes depending on the deviation of the controlled air-fuel ratio from the target value at the time of restart (change in responsiveness). On the other hand, in the present invention, the period until the feedback control converges is the period until the output of the oxygen concentration sensor changes in a predetermined cycle. The fact that the output of the oxygen concentration sensor has changed by a predetermined cycle means that the entire control system for controlling the air-fuel ratio has actually started to follow or has followed the target value of the air-fuel ratio. Therefore, even if there is a change in the responsiveness of the output of the oxygen concentration sensor or a change in the responsiveness of feedback control including integral processing, as mentioned above, the entire control system for controlling the air-fuel ratio is When the air-fuel ratio starts to follow the target value or has started to follow it, the integral constant can be returned to a smaller value without causing any time lag. Therefore, according to the present invention, the integral constant increases for almost the necessary and sufficient period (i.e., a relatively large deviation from the target value at the time of restarting feedback control can be resolved with good response, and hunting does not occur). Since the period of time is shorter than when the air-fuel ratio control occurs, and a not-large integral constant is normally used, the stability of the air-fuel ratio control is not reduced, and hunting and the like can be prevented. Note that, in the present invention, the time when feedback control is restarted from a stopped state of feedback control to a state near an idle state where feedback control is performed is not limited to the time of transition from a deceleration state to an idle state. This is because feedback control is stopped or restarted even if the vehicle is continuously in an idle state or near an idle state. In other words, this feedback control is stopped when the feedback control is undesirable, and is not independently related to whether or not the vehicle is in an idling state or the state of the throttle valve. (It is also related to engine speed etc.)
以下、図面を参照して、本発明に係る内燃機関
の空燃比制御方法が採用された空燃比制御装置の
実施例を詳細に説明する。
本実施例は、第１図に示す如く、エンジン燃焼
室から排気ガスが排出される排気マニホルドに配
設され、該排気マニホルドの下流側に配設される
触媒、例えば三元触媒に流入する触媒流入ガス中
の残存酸素濃度を感知する酸素濃度センサ１０
と、混合気を形成するための燃料通路或いはエア
ブリード通路の有効面積を制御することにより、
或いは、排気ガスに混入される２次空気の流量を
制御することにより、混合気或いは触媒流入ガス
の空燃比を制御する、制御電磁弁等からなる空燃
比制御アクチユエータ１２と、前記酸素濃度セン
サ１０の出力を参照電圧と比較し、触媒流入ガス
の空燃比がリツチ状態であるかリーン状態である
かを判別するリツチ−リーン判定器１４と、アイ
ドル状態に適した第１の積分定数K0で前記リツ
チ−リーン判定器１４の出力を積分して、空燃比
に応じた帰還制御信号を作成する第１の積分器１
６と、オフアイドル状態に適した第２の積分定数
K1で前記リツチ−リーン判定器１４の出力を積
分して、空燃比に応じた帰還制御信号を作成する
第２の積分器１８と、エンジンの吸気管負圧、エ
ンジン回転数、及び、エンジン冷却水温に応じ
て、アイドル状態がオフアイドル状態であるかを
判別する第１の条件判別器２０と、該条件判別器
２０の出力に応じて、アイドル状態である場合に
は前記第１の積分器１６出力を選択し、一方、オ
フアイドル状態である場合には前記第２の積分器
１８の出溶を選択して出力する第１の切換回路２
２と、同じくエンジンの吸気管負圧、エンジン回
転数、及び、エンジン冷却水温に応じて、所定の
帰還停止条件が成立した時に、帰還停止信号を出
力する帰還停止信号出力回路２４と、該帰還停止
信号出力回路２４から帰還停止信号が出力された
時に、前記切換回路２２の出力を遮断する帰還停
止回路２６と、該帰還停止回路２６の出力に応じ
て、前記空燃比制御アクチユエータ１２を駆動す
るのに適した駆動出力を発生する駆動回路２８と
を備えた内燃機関の空燃比制御装置において、前
記アイドル状態の積分定数K0とは異なる第３の
積分定数K2を用いて、前記リツチ−リーン判定
器１４出力を積分し、空燃比に応じた帰還制御信
号を作成する第３の積分器３０と、前記帰還停止
信号出力回路２４の出力及び酸素濃度センサ１０
の出力に応じて、前記帰還停止信号がオフとなつ
てから前記酸素濃度センサ１０の出力が一サイク
ル変化するまでの間、切換信号を出力する第２の
条件判別器３２と、該第２の条件判別器３２から
切換信号が出力されている間は、前記帰還停止回
路２６の出力の代りに前記第３の積分器３０の出
力を前記駆動回路２８に入力する第２の切換回路
３４とを設けたものである。
前記第３の積分器３０における第３の積分定数
K2の大きさは、例えば、前記第１の積分器１６
におけるアイドル時の第１の積分定数K0より大
とされている。なおこの第３の積分定数K2と第
１の積分定数K0との大小関係、及び、第３の積
分定数K2と第２の積分器１８で設定された第２
の積分定数K1との大小関係は、エンジン特性に
応じて最適なものとなるようにされている。
以下第２図を参照して作用を説明する。まず通
常の運転状態、即ち、オフアイドル状態において
は、第１の条件判別器２０の出力に応じて、切換
回路２２により、第２の積分器１８の出力が、帰
還停止回路２６及び第２の切換回路３４を経て駆
動回路２８に入力され、空燃比制御アクチユエー
タ１２は、オフアイドル状態に適した第２の積分
定数K1によつて積分処理された帰還制御信号に
より帰還制御されている。このオフアイドル状態
から、減速状態等に移つて帰還停止条件が成立す
ると、前記帰還停止信号出力回路２４から帰還停
止信号が帰還停止回路２２６に入力される。する
と帰還停止回路２６が開かれ、前記切換回路２２
の出力が前記第２の切換回路３４に入力されなく
なつて、帰還停止状態となる。減速状態が終了
し、エンジン回転数が所定回転数以下となり、し
かも、エンジンの吸気管負圧が所定値以上となつ
て、アイドル状態に移ると、前記帰還停止条件が
成立しなくなり、帰還停止回路２６が接続状態に
戻されると共に、第１の条件判別器２０の出力に
より第１の切換回路２２が切換えられて、第１の
積分器１６の出力が帰還停止回路２６に入力され
ることとなる。この時において、従来は、第２図
の破線Ａに示す如く、直ちにこのアイドル状態に
適した第１の積分定数K0により処理された帰還
制御信号によつて前記空燃比制御アクチユエータ
１２を制御するようにしていたため、このアイド
ル制御開始時に、積分定数が小さ過ぎて酸素濃度
センサの応答遅れ等による制御遅れを生じたり
（第２図の場合）、又は逆に制御過補償によるオー
バーシユートを発生する等の問題があつた。これ
に対して、本発明においては、第２図の実線Ｂに
示す如く、この帰還停止状態からアイドル状態に
移行する際に、前記帰還停止信号出力回路２４か
ら出力される帰還停止信号がオフとなつてから、
前記酸素濃度センサ１０の出力が１サイクル変化
するまでの間は、前記第２の条件判別器３２出力
の切換信号によつて前記切換回路３４を一時的に
切換え、帰還停止状態からアイドル状態に移行す
る際に適した第３の積分定数K2により前記酸素
濃度センサ１０の出力を処理することによつて得
られる帰還信号により、前記空燃比制御アクチユ
エータ１２を制御するようにしている。従つて、
帰還停止状態からアイドル状態に移行する際の、
積分定数過小による制御遅れ（第２図の場合）或
いは逆に制御のオーバーシユート等の問題が解消
されるものである。
なお前記実施例においては、アイドル状態の積
分定数K0とは異なる第３の積分定数K2を用いて
前記酸素濃度センサ１０の出力を処理することに
よつて得られる帰還制御信号により前記空燃比制
御アクチユエータ１２を帰還制御する時間を、ア
イドル状態にしてから、酸素濃度センサ１０の出
力が１サイクル変化する間としていたが、前記第
３の積分定数により帰還制御を行なう時間はこれ
に限定されず、例えば、２サイクル以上の任意の
サイクルとしたり、或いは、酸素濃度センサ１０
の出力がリツチ信号からリーン信号に変わるまで
の間とすることも可能である。
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an air-fuel ratio control device employing an air-fuel ratio control method for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. In this embodiment, as shown in FIG. 1, exhaust gas is disposed in an exhaust manifold from which exhaust gas is discharged from an engine combustion chamber, and the catalyst flows into a catalyst disposed downstream of the exhaust manifold, for example, a three-way catalyst. Oxygen concentration sensor 10 that senses the residual oxygen concentration in the inflowing gas
By controlling the effective area of the fuel passage or air bleed passage for forming the mixture,
Alternatively, an air-fuel ratio control actuator 12 consisting of a control solenoid valve or the like that controls the air-fuel ratio of the air-fuel mixture or catalyst inflow gas by controlling the flow rate of secondary air mixed into the exhaust gas, and the oxygen concentration sensor 10 a rich-lean determiner 14 that compares the output of a first integrator 1 that integrates the output of the rich-lean determiner 14 to create a feedback control signal according to the air-fuel ratio;
6 and a second integral constant suitable for off-idle conditions.
A second integrator 18 that integrates the output of the rich-lean determiner 14 at K1 to create a feedback control signal according to the air-fuel ratio; A first condition discriminator 20 that discriminates whether the idle state is an off-idle state according to the cooling water temperature, and the first integral when the idle state is determined according to the output of the condition discriminator 20. a first switching circuit 2 that selects the output of the second integrator 16 and outputs the output of the second integrator 18 in the off-idle state;
2, a feedback stop signal output circuit 24 that outputs a feedback stop signal when a predetermined feedback stop condition is satisfied, similarly according to the engine intake pipe negative pressure, engine speed, and engine cooling water temperature; A feedback stop circuit 26 that cuts off the output of the switching circuit 22 when a feedback stop signal is output from the stop signal output circuit 24; and a feedback stop circuit 26 that drives the air-fuel ratio control actuator 12 in accordance with the output of the feedback stop circuit 26. In the air - fuel ratio control device for an internal combustion engine, the air-fuel ratio control device for an internal combustion engine is equipped with a drive circuit 28 that generates a drive output suitable for the rich engine. a third integrator 30 that integrates the output of the lean determiner 14 and creates a feedback control signal according to the air-fuel ratio; the output of the feedback stop signal output circuit 24; and the oxygen concentration sensor 10.
a second condition discriminator 32 that outputs a switching signal from when the feedback stop signal is turned off until the output of the oxygen concentration sensor 10 changes by one cycle according to the output of the second condition discriminator 32; While the switching signal is being output from the condition discriminator 32, a second switching circuit 34 inputs the output of the third integrator 30 to the drive circuit 28 instead of the output of the feedback stop circuit 26. It was established. third integral constant in the third integrator 30
The magnitude of K 2 is, for example, the first integrator 16
is larger than the first integral constant K 0 at idle. Note that the magnitude relationship between the third integral constant K 2 and the first integral constant K 0 and the second integral constant K 2 and the second integral constant set by the second integrator 18 are
The magnitude relationship between K and the integral constant K1 is optimized depending on the engine characteristics. The operation will be explained below with reference to FIG. First, in a normal operating state, that is, an off-idle state, the switching circuit 22 switches the output of the second integrator 18 to the feedback stop circuit 26 and the second The air-fuel ratio control actuator 12 is feedback-controlled by a feedback control signal that is input to the drive circuit 28 via the switching circuit 34 and has been integrated by a second integral constant K 1 suitable for the off-idle state. When the off-idle state shifts to a deceleration state or the like and the feedback stop condition is satisfied, a feedback stop signal is input from the feedback stop signal output circuit 24 to the feedback stop circuit 226. Then, the feedback stop circuit 26 is opened, and the switching circuit 22
The output is no longer input to the second switching circuit 34, and the feedback is stopped. When the deceleration state ends and the engine speed becomes less than the predetermined number of revolutions, and the negative pressure in the intake pipe of the engine exceeds the predetermined value, and the engine shifts to the idle state, the feedback stop condition is no longer satisfied, and the feedback stop circuit 26 is returned to the connected state, the first switching circuit 22 is switched by the output of the first condition discriminator 20, and the output of the first integrator 16 is input to the feedback stop circuit 26. . At this time, conventionally, as shown by the broken line A in FIG. 2, the air-fuel ratio control actuator 12 is immediately controlled by a feedback control signal processed by the first integral constant K 0 suitable for this idle state. As a result, at the start of this idle control, the integral constant is too small, resulting in a control delay due to a delay in the response of the oxygen concentration sensor, etc. (as shown in Figure 2), or conversely, an overshoot due to control overcompensation. There were problems such as: In contrast, in the present invention, as shown by the solid line B in FIG. 2, when transitioning from the feedback stop state to the idle state, the feedback stop signal output from the feedback stop signal output circuit 24 is turned off. After getting older,
Until the output of the oxygen concentration sensor 10 changes by one cycle, the switching circuit 34 is temporarily switched by the switching signal of the output of the second condition discriminator 32, and the state shifts from the feedback stop state to the idle state. The air-fuel ratio control actuator 12 is controlled by a feedback signal obtained by processing the output of the oxygen concentration sensor 10 using a third integral constant K 2 suitable for this purpose. Therefore,
When transitioning from return stop state to idle state,
This eliminates problems such as control delays (as in the case of FIG. 2) or control overshoots due to too small an integral constant. In the embodiment, the air-fuel ratio is adjusted by the feedback control signal obtained by processing the output of the oxygen concentration sensor 10 using a third integral constant K 2 different from the integral constant K 0 in the idle state. Although the time period for feedback control of the control actuator 12 was defined as the period from the idle state to the period during which the output of the oxygen concentration sensor 10 changes by one cycle, the time period for performing feedback control using the third integral constant is not limited to this. , for example, an arbitrary cycle of two or more cycles, or the oxygen concentration sensor 10
It is also possible to set the period until the output of the signal changes from a rich signal to a lean signal.
以上説明した通り、本発明によれば、帰還制御
の停止状態からアイドル状態近傍の帰還制御を行
うべき状態に移行する帰還制御の再開時、帰還制
御の積分を含む処理等による応答性の低下や、酸
素濃度センサの低応答性による制御遅れ、或いは
制御過補償によるオーバーシユートやハンチング
等が解消され、空燃比制御性が向上するという優
れた効果を有する。
As explained above, according to the present invention, when feedback control is restarted from a stopped state of feedback control to a state in which feedback control should be performed near an idle state, a decrease in responsiveness due to processing including integration of feedback control, etc. This has the excellent effect of eliminating control delays due to low responsiveness of the oxygen concentration sensor, overshooting and hunting due to control overcompensation, and improving air-fuel ratio controllability.
第１図は、本発明に係る内燃機関の空燃比制御
方法が採用された空燃比制御装置の実施例の構成
を示すブロツク線図、第２図は、前記実施例の各
部動作波形を示す線図である。
１０……酸素濃度センサ、１２……空燃比制御
アクチユエータ、１４……リツチ−リーン判定
器、１６，１８，３０……積分器、２０，３２…
…条件判別器、２２，３４……切換回路、２４…
…帰還停止信号出力回路、２６……帰還停止回
路、２８……駆動回路。
FIG. 1 is a block diagram showing the configuration of an embodiment of an air-fuel ratio control device in which the air-fuel ratio control method for an internal combustion engine according to the present invention is adopted, and FIG. 2 is a diagram showing the operation waveforms of each part of the embodiment. It is a diagram. 10... Oxygen concentration sensor, 12... Air-fuel ratio control actuator, 14... Rich Lean determiner, 16, 18, 30... Integrator, 20, 32...
...Condition discriminator, 22, 34...Switching circuit, 24...
...Feedback stop signal output circuit, 26...Feedback stop circuit, 28...Drive circuit.
Claims (1)
素濃度センサと、混合気或いは触媒流入ガスの空
燃比を制御する空燃比制御アクチユエータとを用
い、前記酸素濃度センサの出力に対して積分を含
む処理を施すことによつて得られる帰還制御信号
により前記空燃比制御アクチユエータを帰還制御
して、混合気或いは触媒流入ガスの空燃比を所望
空燃比とし、又、必要に応じて該帰還制御を停止
する内燃機関の空燃比制御方法において、 前記帰還制御の停止状態から、アイドル状態近
傍の帰還制御を行うべき状態に移行する帰還制御
の再開時、 酸素濃度センサの出力が所定サイクル変化する
まで、前記アイドル状態近傍の前記帰還制御に用
いられる積分定数より大きい積分定数を用いて前
記酸素濃度センサの出力を処理することによつて
得られる帰還制御信号により、前記空燃比アクチ
ユエータを帰還制御することを特徴とする内燃機
関の空燃比制御方法。[Claims] 1. Using an oxygen concentration sensor that detects the residual oxygen concentration in the catalyst inflow gas and an air-fuel ratio control actuator that controls the air-fuel ratio of the air-fuel mixture or the catalyst inflow gas, the output of the oxygen concentration sensor The air-fuel ratio control actuator is feedback-controlled by a feedback control signal obtained by performing processing including integration on the air-fuel ratio, and the air-fuel ratio of the air-fuel mixture or the catalyst inflow gas is set to the desired air-fuel ratio, and as necessary. In the air-fuel ratio control method for an internal combustion engine in which the feedback control is stopped, when the feedback control is restarted from the stopped state of the feedback control to a state where the feedback control should be performed near the idle state, the output of the oxygen concentration sensor is changed to a predetermined cycle. feedback control signal obtained by processing the output of the oxygen concentration sensor using an integral constant larger than the integral constant used for the feedback control near the idle state until the air-fuel ratio actuator 1. A method for controlling an air-fuel ratio of an internal combustion engine.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13875681A JPS5848741A (en) | 1981-09-03 | 1981-09-03 | Method of controlling air-fuel ratio of internal- combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13875681A JPS5848741A (en) | 1981-09-03 | 1981-09-03 | Method of controlling air-fuel ratio of internal- combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5848741A JPS5848741A (en) | 1983-03-22 |
| JPH0325623B2 true JPH0325623B2 (en) | 1991-04-08 |
Family
ID=15229443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13875681A Granted JPS5848741A (en) | 1981-09-03 | 1981-09-03 | Method of controlling air-fuel ratio of internal- combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5848741A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5297031A (en) * | 1976-02-12 | 1977-08-15 | Nissan Motor Co Ltd | Air fuel ration controller |
| JPS5618037A (en) * | 1979-07-23 | 1981-02-20 | Nissan Motor Co Ltd | Fuel controller |
-
1981
- 1981-09-03 JP JP13875681A patent/JPS5848741A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5297031A (en) * | 1976-02-12 | 1977-08-15 | Nissan Motor Co Ltd | Air fuel ration controller |
| JPS5618037A (en) * | 1979-07-23 | 1981-02-20 | Nissan Motor Co Ltd | Fuel controller |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5848741A (en) | 1983-03-22 |
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