JPH0319377B2 - - Google Patents
Info
- Publication number
- JPH0319377B2 JPH0319377B2 JP22613384A JP22613384A JPH0319377B2 JP H0319377 B2 JPH0319377 B2 JP H0319377B2 JP 22613384 A JP22613384 A JP 22613384A JP 22613384 A JP22613384 A JP 22613384A JP H0319377 B2 JPH0319377 B2 JP H0319377B2
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- fuel
- target value
- output
- 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
Links
- 239000000446 fuel Substances 0.000 claims description 207
- 239000007789 gas Substances 0.000 claims description 26
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 13
- 239000001301 oxygen Substances 0.000 claims description 13
- 229910052760 oxygen Inorganic materials 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 8
- 238000002347 injection Methods 0.000 description 36
- 239000007924 injection Substances 0.000 description 36
- 239000004215 Carbon black (E152) Substances 0.000 description 16
- 229930195733 hydrocarbon Natural products 0.000 description 16
- 150000002430 hydrocarbons Chemical class 0.000 description 16
- 238000010586 diagram Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 5
- 239000007784 solid electrolyte Substances 0.000 description 4
- 229910006404 SnO 2 Inorganic materials 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229910020599 Co 3 O 4 Inorganic materials 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- -1 NiO Chemical class 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Description
【発明の詳細な説明】
(産業上の利用分野)
本発明は、エンジンの空燃比制御装置に関し、
特に排気ガス中の酸素濃度に応じてその出力がリ
ニアに変化しかつ出力値によつて出力勾配が異な
る空燃比センサを用いてエンジンの空燃比を所定
値にフイードバツク制御するようにしたものに関
する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air-fuel ratio control device for an engine.
In particular, the present invention relates to an engine in which the air-fuel ratio of the engine is feedback-controlled to a predetermined value using an air-fuel ratio sensor whose output varies linearly in accordance with the oxygen concentration in exhaust gas and whose output gradient varies depending on the output value.
(従来の技術)
従来より、エンジンの排気ガス中の酸素濃度に
よりエンジンの空燃比を検出してエンジンに供給
する混合気の空燃比を所定値にフイードバツク制
御することは広く知られている。(Prior Art) It is widely known that the air-fuel ratio of the engine is detected based on the oxygen concentration in the exhaust gas of the engine, and the air-fuel ratio of the air-fuel mixture supplied to the engine is feedback-controlled to a predetermined value.
そして、この場合、排気ガス中の酸素濃度を検
出して間接的に空燃比を検出する空燃比センサと
しては、理論空燃比に対応する酸素濃度を境にし
て出力(起電力)がステツプ状に変化する、いわ
ゆるλセンサがある。このλセンサは、その出力
特性から空燃比を理論空燃比に制御する場合には
好適であるが、加速時や高負荷運転時等、高出力
が要求されるときに空燃比を理論空燃比よりもリ
ツチに設定する場合、あるいは高速定常走行時に
おいて燃費向上のために空燃比を理論空燃比より
もリーンに設定する場合には、上述の如く理論空
燃比に対する大小のみを判別するだけであるの
で、これら理論空燃比からリーン又はリツチ側に
外れた空燃比を正確に検出することはできず、空
燃比を任意の値に制御する場合には不向きであ
る。 In this case, the air-fuel ratio sensor, which indirectly detects the air-fuel ratio by detecting the oxygen concentration in the exhaust gas, outputs (electromotive force) in steps at the oxygen concentration corresponding to the stoichiometric air-fuel ratio. There are so-called λ sensors that vary. This λ sensor is suitable for controlling the air-fuel ratio to the stoichiometric air-fuel ratio due to its output characteristics, but when high output is required, such as during acceleration or high-load operation, the air-fuel ratio is lower than the stoichiometric air-fuel ratio. When setting the air-fuel ratio to be richer, or when setting the air-fuel ratio leaner than the stoichiometric air-fuel ratio to improve fuel efficiency during steady high-speed driving, only the magnitude relative to the stoichiometric air-fuel ratio is determined as described above. , it is not possible to accurately detect air-fuel ratios that deviate from the stoichiometric air-fuel ratio to the lean or rich side, and it is not suitable for controlling the air-fuel ratio to an arbitrary value.
そこで、上記λセンサに代わる空燃比センサの
一つとして、特開昭59−100854号公報に示される
ように、排気ガス中の酸素濃度に応じて出力がリ
ニアに変化して、空燃比をリツチ領域からリーン
領域に亘つて連続的に検出できる、いわゆる広域
空燃比センサが提案されており、このものにより
空燃比を任意の値に制御することを可能としてい
る。すなわち、この広域空燃比センサは、酸素イ
オン伝導性の固体電解質の両面に多孔質電極を形
成し、被測定ガス(排気ガス)に接触する側の多
孔質電極としてPt等を主成分とする半触媒性能
を有するものを使用するとともに、該電極と固体
電解質と被測定ガスとで構成される3相点近傍
に、HCを酸化してCOを生成するSnO2等の金属
酸化物を存在させてなるものである。 Therefore, as an air-fuel ratio sensor that replaces the above-mentioned λ sensor, as shown in Japanese Patent Application Laid-Open No. 59-100854, the output changes linearly according to the oxygen concentration in the exhaust gas, and the air-fuel ratio is enriched. A so-called wide-range air-fuel ratio sensor has been proposed that can continuously detect the air-fuel ratio from the lean region to the lean region, and makes it possible to control the air-fuel ratio to an arbitrary value. In other words, this wide-range air-fuel ratio sensor has porous electrodes formed on both sides of an oxygen ion-conducting solid electrolyte, and a semi-porous electrode mainly made of Pt etc. as the porous electrode on the side that comes into contact with the gas to be measured (exhaust gas). In addition to using a material with catalytic performance, a metal oxide such as SnO 2 that oxidizes HC to generate CO is present near the three-phase point consisting of the electrode, solid electrolyte, and gas to be measured. It is what it is.
(発明が解決しようとする課題)
ところで、上記広域空燃比センサのようにリニ
アな出力特性を有する空燃比センサを用いてエン
ジンの空燃比を所定値にフイードバツク制御する
場合、ノイズの影響を考慮して、目標空燃比に対
応する空燃比センサの目標値に所定幅の不感帯
(ヒステリシス)を設けて、空燃比を所定の不感
帯幅で目標値につまり所定の範囲内に制御するこ
とにより、耐ノイズ性を高めることが考えられる
(第6図参照)。(Problems to be Solved by the Invention) By the way, when feedback controlling the air-fuel ratio of the engine to a predetermined value using an air-fuel ratio sensor having linear output characteristics such as the above-mentioned wide-range air-fuel ratio sensor, it is necessary to take into account the influence of noise. By setting a dead band (hysteresis) of a predetermined width at the target value of the air-fuel ratio sensor corresponding to the target air-fuel ratio, and controlling the air-fuel ratio to the target value with the predetermined dead band width, that is, within a predetermined range, noise resistance is achieved. It is possible to increase the sexiness (see Figure 6).
しかるに、このようにリニアな出力特性の空燃
比センサであつても、その出力特性は正確にはリ
ニアでなくほぼリニアにすぎず、出力値によつて
出力勾配が異なつている。例えば、上記広域空燃
比センサの場合、その出力(起電力)特性は、理
論空燃比(A/F=14.7)で起電力勾配(傾斜)
が最大で、この理論空燃比を境にしてリーン側お
よびリツチ側に行くにつれて起電力勾配がゆるや
かになる特性を有する(第3図参照)。そのため、
この広域空燃比センサの場合、起電力勾配の大き
い理論空燃比付近を基準にしてノイズ対策から不
感帯の幅を大きく設定すると、理論空燃比よりも
リーン側又はリツチ側では、起電力勾配がゆるや
かであることから、上記不感帯により空燃比の変
動が増長されることになり、空燃比制御の精度を
低下させるという問題がある。 However, even with an air-fuel ratio sensor having such a linear output characteristic, the output characteristic is not exactly linear but only approximately linear, and the output gradient differs depending on the output value. For example, in the case of the above-mentioned wide range air-fuel ratio sensor, its output (electromotive force) characteristic is an electromotive force gradient (slope) at the stoichiometric air-fuel ratio (A/F = 14.7).
is the maximum, and the electromotive force gradient becomes gentler toward the lean side and rich side from this stoichiometric air-fuel ratio (see Fig. 3). Therefore,
In the case of this wide-range air-fuel ratio sensor, if the width of the dead zone is set large for noise countermeasures based on the vicinity of the stoichiometric air-fuel ratio where the electromotive force gradient is large, the electromotive force gradient will be gentler on the lean or rich side than the stoichiometric air-fuel ratio. For this reason, there is a problem in that the dead zone increases fluctuations in the air-fuel ratio, reducing the accuracy of air-fuel ratio control.
本発明はかかる点に鑑みてなされたもので、そ
の目的とするところは、出力がリニアに変化しか
つ出力値によつて出力勾配が異なる空燃比センサ
を用いて空燃比を所定の不感帯幅で目標空燃比に
つまり所定の範囲内に制御する場合、この不感帯
幅を空燃比センサからの出力値における出力勾配
に応じて変更することにより、空燃比制御の精度
を低下させることなく耐ノイズ性を向上させるこ
とにある。 The present invention has been made in view of the above, and its purpose is to control the air-fuel ratio within a predetermined dead band width using an air-fuel ratio sensor whose output changes linearly and whose output gradient varies depending on the output value. When controlling the air-fuel ratio to the target air-fuel ratio, that is, within a predetermined range, by changing this dead band width according to the output gradient of the output value from the air-fuel ratio sensor, noise resistance can be improved without reducing the accuracy of air-fuel ratio control. It's about improving.
(課題を解決するための手段)
上記の目的を達成するため、本発明の解決手段
は、第1図に示すように、エンジンの排気通路中
に設けられ、排気ガス中の酸素濃度に応じてその
出力がリニアに変化しかつ出力値によつて出力勾
配が異なる空燃比センサ8と、予め設定された混
合気の空燃比に対応した上記空燃比センサ8の目
標値を設定する目標値設定手段15と、上記空燃
比センサ8の出力と目標値設定手段15により設
定された目標値とを比較する比較手段17と、該
比較手段17の出力を受け、エンジンに供給する
混合気の空燃比を所定の不感帯幅で上記目標値に
制御する空燃比制御手段18とを備えることを基
本構成とする。これに加えて、上記空燃比センサ
8からの出力値における出力勾配が小さいときに
は大きいときと比較して上記空燃比制御手段18
の不感帯幅を小さくするように変更する制御範囲
変更手段16を設ける構成としたものである。(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is provided in the exhaust passage of an engine, as shown in FIG. An air-fuel ratio sensor 8 whose output varies linearly and whose output gradient varies depending on the output value, and target value setting means for setting a target value of the air-fuel ratio sensor 8 corresponding to a preset air-fuel ratio of the air-fuel mixture. 15, a comparison means 17 for comparing the output of the air-fuel ratio sensor 8 and the target value set by the target value setting means 15, and a comparison means 17 that receives the output of the comparison means 17 and determines the air-fuel ratio of the air-fuel mixture to be supplied to the engine. The basic configuration includes an air-fuel ratio control means 18 that controls the above-mentioned target value with a predetermined dead band width. In addition, when the output gradient of the output value from the air-fuel ratio sensor 8 is small, compared to when it is large, the air-fuel ratio control means 18
This configuration includes a control range changing means 16 that changes the dead zone width so as to reduce the width of the dead zone.
(作用)
上記の構成により、本発明では、排気ガス中の
酸素濃度に応じてその出力がリニアに変化しかつ
出力値によつて出力勾配が異なる空燃比センサを
用いて空燃比を所定の範囲内にフイードバツク制
御する場合、目標空燃比に対応する空燃比センサ
の目標値(目標起電力)の不感帯幅が空燃比セン
サからの出力値における出力勾配に応じて出力勾
配が小さいときには大きいときと比較して小さく
なるように変更される。例えば、上記広域空燃比
センサの場合、不感帯幅は、起電力勾配が最大で
ある理論空燃比付近では最大に、理論空燃比より
もリーン側又はリツチ側に行くにしたがつて、つ
まり起電力勾配がゆるやかになるにしたがつて小
さくなる。このことにより、不感帯幅が大きいと
きには、出力勾配が大きいことにより不感帯によ
る空燃比の変動をさほど生じることなく耐ノイズ
性が著しく高められる。一方、不感帯幅が小さい
ときには、出力勾配が小さいことにより、耐ノイ
ズ性をある程度確保しながら、不感帯による空燃
比の変動の増長が抑制され、制御精度の低下が防
止されることになる。(Function) With the above configuration, the present invention uses an air-fuel ratio sensor whose output changes linearly according to the oxygen concentration in the exhaust gas and whose output gradient varies depending on the output value to control the air-fuel ratio within a predetermined range. In the case of feedback control, the width of the dead band of the target value (target electromotive force) of the air-fuel ratio sensor corresponding to the target air-fuel ratio is compared when the output gradient is small and when it is large according to the output gradient of the output value from the air-fuel ratio sensor. It will be changed to become smaller. For example, in the case of the above-mentioned wide range air-fuel ratio sensor, the dead band width is maximum near the stoichiometric air-fuel ratio where the electromotive force gradient is maximum, and as it goes leaner or richer than the stoichiometric air-fuel ratio, that is, the electromotive force gradient becomes smaller as it becomes more gradual. As a result, when the width of the dead zone is large, the output gradient is large, so that the air-fuel ratio does not fluctuate much due to the dead zone, and the noise resistance is significantly improved. On the other hand, when the dead band width is small, the output gradient is small, so while ensuring noise resistance to some extent, the increase in air-fuel ratio fluctuations due to the dead band is suppressed, and a decrease in control accuracy is prevented.
(実施例)
以下、本発明の実施例を第2図以下の図面に基
づいて説明する。(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.
第2図は本発明の一実施例に係るエンジンの空
燃比制御システムの概略構成を示し、1はエンジ
ン、2はエンジン1に吸気を供給するための吸気
通路、3はエンジン1からの排気ガスを排出する
ための排気通路である。上記吸気通路2には、エ
ンジン1に供給する吸入空気量を制御するスロツ
トル弁4が配設され、該スロツトル弁4下流の吸
気通路2にはエンジン1に燃料を噴射供給する燃
料噴射弁5が配設されている。 FIG. 2 shows a schematic configuration of an engine air-fuel ratio control system according to an embodiment of the present invention, in which 1 is an engine, 2 is an intake passage for supplying intake air to the engine 1, and 3 is an exhaust gas from the engine 1. This is an exhaust passage for discharging. A throttle valve 4 for controlling the amount of intake air supplied to the engine 1 is disposed in the intake passage 2, and a fuel injection valve 5 for injecting fuel to the engine 1 is disposed in the intake passage 2 downstream of the throttle valve 4. It is arranged.
また、上記吸気通路2のスロツトル弁4上流に
は、吸入空気量を検出するエアフローセンサ6お
よび吸気の温度を検出する吸気温センサ7が設け
られている。一方、上記排気通路3には、排気ガ
ス中の酸素濃度により空燃比を検出する空燃比セ
ンサ8、排気ガス中の炭化水素(HC)濃度を検
出するHCセンサ9および排気ガス濃度により上
記空燃比センサ8の温度を検出する排気温センサ
10が設けられており、これらセンサ6〜10の
各出力は、上記燃料噴射弁5を制御する空燃比コ
ントローラ11に入力されている。また、12は
点火プラグ、13はイグニツシヨンコイル、14
はイグナイタであつて、該イグナイタ14からの
点火信号はエンジン回転数信号等として上記空燃
比コントローラ11に入力されている。 Further, upstream of the throttle valve 4 in the intake passage 2, an air flow sensor 6 for detecting the amount of intake air and an intake temperature sensor 7 for detecting the temperature of intake air are provided. On the other hand, the exhaust passage 3 includes an air-fuel ratio sensor 8 that detects the air-fuel ratio based on the oxygen concentration in the exhaust gas, an HC sensor 9 that detects the hydrocarbon (HC) concentration in the exhaust gas, and an air-fuel ratio sensor 9 that detects the air-fuel ratio based on the oxygen concentration in the exhaust gas. An exhaust temperature sensor 10 is provided to detect the temperature of the sensor 8, and the outputs of these sensors 6 to 10 are input to an air-fuel ratio controller 11 that controls the fuel injection valve 5. Also, 12 is a spark plug, 13 is an ignition coil, 14
is an igniter, and the ignition signal from the igniter 14 is inputted to the air-fuel ratio controller 11 as an engine rotational speed signal or the like.
上記空燃比センサ8は、既術の如く酸素イオン
伝導性の固体電解質の両面に多孔質電極を形成
し、被測定ガス(排気ガス)に接触する側の多孔
質電極としてPt等の半触媒性能を有するものを
使用するとともに、該電極と固体電解質と被測定
ガス(排気ガス)とで構成される3相点近傍に、
HCを酸化してCOを生成するSnO2、In2O3、
NiO、Co3O4、CnO等の金属酸化物を存在させて
なるもので、その起電力特性は第3図に示すよう
に排気ガス中の酸素濃度に応じてその出力として
の起電力がリニアに変化して、空燃比をリツチ領
域からリーン領域に亘つて連続的に検出できる基
本特性を有するいわゆる広域空燃比センサであ
り、理論空燃比付近で出力勾配が最大で、理論空
燃比よりリーン側又はリツチ側に行くに従つて出
力勾配が小さくなるものである。また、この空燃
比センサ8の超電力特性は、空燃比センサ8の温
度(排気ガス温度)により変化する温度特性を有
し、該温度が高くなるに従つて理論空燃比よりも
リーン側では起電力が低下し、リツチ側では起電
力が増大する。また、上記空燃比センサ8の起電
力は、排気ガス中のHC濃度により変化するHC
濃度特性を有し、理論空燃比よりもリーン側で
HC濃度が大になるにつれて起電力が増大する
(尚、リツチ側では元来HC濃度が高いのでほと
んど起電力の変化は生じない)。 The air-fuel ratio sensor 8 has porous electrodes formed on both sides of an oxygen ion-conducting solid electrolyte as in the past, and the porous electrode on the side that comes into contact with the gas to be measured (exhaust gas) has a semi-catalytic performance such as Pt. In addition, near the three-phase point consisting of the electrode, solid electrolyte, and gas to be measured (exhaust gas),
SnO 2 , In 2 O 3 , which oxidizes HC to produce CO;
It is made by the presence of metal oxides such as NiO, Co 3 O 4 and CnO, and its electromotive force characteristics are such that the output electromotive force is linear according to the oxygen concentration in the exhaust gas, as shown in Figure 3. It is a so-called wide-range air-fuel ratio sensor that has the basic characteristics of being able to continuously detect the air-fuel ratio from the rich region to the lean region. Alternatively, the output gradient becomes smaller as it goes to the richer side. Moreover, the superpower characteristic of the air-fuel ratio sensor 8 has a temperature characteristic that changes depending on the temperature of the air-fuel ratio sensor 8 (exhaust gas temperature), and as the temperature becomes higher, it occurs on the leaner side than the stoichiometric air-fuel ratio. The power decreases and the electromotive force increases on the rich side. In addition, the electromotive force of the air-fuel ratio sensor 8 varies depending on the HC concentration in the exhaust gas.
It has concentration characteristics and is leaner than the stoichiometric air-fuel ratio.
As the HC concentration increases, the electromotive force increases (note that since the HC concentration is originally high on the rich side, there is almost no change in the electromotive force).
次に、上記空燃比コントローラ11の作動を第
4図に示すフローチヤートにより説明するに、リ
セツト後、ステツプS1で空燃比のリーンゾーンと
リツチゾーンとを区別するためのゾーンフラグ
Fzone(リーン側で“0”、リツチ側で“1”)を
“0”に、燃料噴射がデイレイ中か否かを区別す
るためのリーン側およびリツチ側のデイレイフラ
グFl、Fr(デイレイ中でないときは“0”、デイ
レイ中は“1”)を共に“0”に、またエンジン
回転数と噴射時間との関係を決めるフイードバツ
ク係数Cfbを“1”にそれぞれ初期設定する。さ
らにステツプS2でエンジン回転数等を計算するた
めの一定周期を定める基本タイマをリセツトし
て、次のステツプS3で基本タイマーが一定時間
Ti経過するのを待ち、一定時間Ti経過するとス
テツプS4で上記基本タイマを再びリセツトする。
尚、この基本タイマはリセツトされた瞬間から時
間をアツプカウントするカウンタである。 Next, the operation of the air-fuel ratio controller 11 will be explained with reference to the flowchart shown in FIG.
Fzone (“0” on the lean side, “1” on the rich side) is set to “0”, and delay flags Fl and Fr (not in delay) on the lean side and rich side are used to distinguish whether or not fuel injection is in delay. Initial setting is ``0'' during the injection period and ``1'' during the delay period), and a feedback coefficient Cfb, which determines the relationship between the engine speed and the injection time, is initially set to ``1''. Furthermore, in step S2 , the basic timer that determines a fixed period for calculating engine speed, etc. is reset, and in the next step S3 , the basic timer is reset for a fixed period of time.
Wait for Ti to elapse, and when Ti elapses for a certain period of time, the basic timer is reset again in step S4 .
Note that this basic timer is a counter that counts up the time from the moment it is reset.
次に、ステツプS5でイグナイタ14からのイグ
ニツシヨンパルス信号によりエンジン回転数Ne
を計算し、またステツプS6でエアフローセンサ6
および吸気温センサ7からの信号により吸入空気
流量Ueを計算する。 Next, in step S5 , the engine speed Ne is determined by the ignition pulse signal from the igniter 14.
Calculate the airflow sensor 6 in step S6.
And the intake air flow rate Ue is calculated based on the signal from the intake temperature sensor 7.
次いで、ステツプS7で空燃比センサ8からの出
力信号としての起電力Vs信号、HCセンサ9から
のHC濃度信号および排気温センサ10からの排
気ガス温度信号(空燃比センサ温度信号)を入力
したのち、ステツプS8において目標空燃比、HC
濃度および排気ガス温度を第5図に示すようなデ
ータテーブルに入力して、目標空燃比に対応する
空燃比センサ8の目標値としてのスライスレベル
中央値Vrefを求めるとともに、該目標値として
のスライスレベル中央値Vrefに対するリーン側
およびリツチ側の不感帯幅Vhl、Vhrを求める。 Next, in step S7 , the electromotive force Vs signal as an output signal from the air-fuel ratio sensor 8, the HC concentration signal from the HC sensor 9, and the exhaust gas temperature signal from the exhaust temperature sensor 10 (air-fuel ratio sensor temperature signal) are input. Later, in step S8 , the target air-fuel ratio, HC
By inputting the concentration and exhaust gas temperature into a data table as shown in FIG. 5, the slice level median value Vref as the target value of the air-fuel ratio sensor 8 corresponding to the target air-fuel ratio is determined, and the slice level value Vref as the target value is calculated. Determine the dead band widths Vhl and Vhr on the lean side and rich side with respect to the level median value Vref.
ここにおいて、上記目標空燃比は例えばエンジ
ン回転数とエンジン負荷によりエンジン運転状態
に応じて設定され、例えば高負荷運転時には目標
空燃比A/Fが理論空燃比(A/F=14.7)より
もリツチに、高速定常走行時には理論空燃比より
もリーンに設定される。また、上記第5図のデー
タテーブルには、各目標空燃比毎に排気ガス濃度
とHC濃度とに応じたスライスレベル中央値Vref
が書き込まれていて、排気ガス温度に対しては理
論空燃比(A/F=14.7)を境にしてリツチ側で
は温度の上昇に伴つてVrefが増大し、リーン側
では温度の上昇に伴つてVrefが低下し、理論空
燃比では温度変化に対してVrefがほぼ一定であ
る。また、HC濃度に対しては理論空燃比(A/
F=14.7)よりもリーン側ではHC濃度の増大に
伴つてVrefが増大し、理論空燃比およびそれよ
りもリツチ側ではHC濃度変化に対してVrefがほ
ぼ一定である。さらに、上記スライスレベル中央
値Vrefに対する不感帯幅(つまりヒステリシス
幅)Vhl、Vhrは、第6図に示すように空燃比セ
ンサ8の出力(起電力)に対するノイズの影響を
なくすために設定されたもので、この不感帯幅
Vhl、Vhr内での起電力の変化を無視してノイズ
に対処している。そして、この不感帯幅Vhl、
Vhrは第7図に示すマツプにより求められ、目標
空燃比に対応するスライスレベル中央値Vrefに
応じて変化し、理論空燃比に相当するスライスレ
ベル中央値Vref0で最大で、理論空燃比よりもリ
ーン側又はリツチ側に相当するスライスレベル中
央値になるにしたがつて小さくなる。 Here, the target air-fuel ratio is set depending on the engine operating state, for example, based on engine speed and engine load. For example, during high-load operation, the target air-fuel ratio A/F is richer than the stoichiometric air-fuel ratio (A/F = 14.7). In addition, during high-speed steady driving, the air-fuel ratio is set to be leaner than the stoichiometric air-fuel ratio. The data table in Figure 5 above also includes slice level median value Vref according to exhaust gas concentration and HC concentration for each target air-fuel ratio.
is written, and for the exhaust gas temperature, Vref increases as the temperature rises on the rich side with the stoichiometric air-fuel ratio (A/F = 14.7) as the boundary, and as the temperature rises on the lean side. Vref decreases, and at the stoichiometric air-fuel ratio, Vref remains almost constant with respect to temperature changes. In addition, for the HC concentration, the stoichiometric air-fuel ratio (A/
On the leaner side than F=14.7), Vref increases as the HC concentration increases, and at the stoichiometric air-fuel ratio and on the richer side, Vref remains almost constant with respect to changes in HC concentration. Furthermore, the dead band widths (that is, hysteresis widths) Vhl and Vhr with respect to the slice level median value Vref are set to eliminate the influence of noise on the output (electromotive force) of the air-fuel ratio sensor 8, as shown in FIG. And this dead band width
Noise is dealt with by ignoring changes in electromotive force within Vhl and Vhr. And this dead band width Vhl,
Vhr is determined by the map shown in Figure 7, and changes according to the slice level median value Vref corresponding to the target air-fuel ratio, and is maximum at the slice level median value Vref corresponding to the stoichiometric air-fuel ratio, which is 0 , and is lower than the stoichiometric air-fuel ratio. It becomes smaller as the slice level median value corresponds to the lean side or the rich side.
しかる後、以下のステツプS9〜S29において、
第8図に示す如き空燃比センサ8の出力特性と燃
料噴射弁5からの平均燃料噴射量との対応関係で
もつて空燃比を所定の不感帯をもつて目標空燃比
にすべくフイードバツク制御が実行される。すな
わち、耐ノイズ性のため空燃比センサ8の目標起
電力の不感帯(ヒステリシス)を決めるべく、先
ず、ステツプS9でゾーンフラグFzoneが“0”か
“1”かを判定し、Fzone=0のリーン側のとき
には、上記ステツプS8で求めたスライスレベル中
央値Vrefに対するリーン側不感帯幅Vhlにより、
ステツプS10でスライスレベル中央値V′refをVref
+Vhlとし、Fzone=1のリツチ側のときには、
上記ステツプS8で求めたスライスレベル中央値
Vrefに対するリツチ側不感帯幅Vhrにより、ステ
ツプS11でスライスレベル中央値V′refVref−Vhr
として、それぞれステツプS12に進む。そして、
ステツプS12で空燃比センサ8からの実測した起
電力Vsで上記ステツプS10又はS11で定めたスラ
イスレベル中央値V′refとの大小を比較判別する。 After that, in the following steps S9 to S29 ,
Feedback control is executed to adjust the air-fuel ratio to the target air-fuel ratio with a predetermined dead zone based on the correspondence between the output characteristics of the air-fuel ratio sensor 8 and the average fuel injection amount from the fuel injection valve 5 as shown in FIG. Ru. That is, in order to determine the dead zone (hysteresis) of the target electromotive force of the air-fuel ratio sensor 8 for noise resistance, first, in step S9 , it is determined whether the zone flag Fzone is "0" or "1", and when Fzone=0, When on the lean side, the lean side dead zone width Vhl is calculated based on the slice level median value Vref obtained in step S8 above.
In step S 10 , the slice level median value V′ref is set to Vref
+Vhl and when on the rich side with Fzone=1,
Median slice level obtained in step S8 above
Based on the rich side dead zone width Vhr with respect to Vref, the slice level median value V′refVref−Vhr is determined in step S11 .
, respectively, proceed to step S12 . and,
In step S12 , the electromotive force Vs actually measured from the air-fuel ratio sensor 8 is compared with the slice level median value V'ref determined in step S10 or S11 .
このステツプS12での判別がVs≧V′refのとき
にはステツプS13でゾーンフラグFzoneの判定を
行い、Fzone=1のリツチ側のときには空燃比が
目標値よりもリツチ側であると判断してステツプ
S14で空燃比をリーン化つまり燃料噴射量を減少
すべくフイードバツク係数CfbをCfb−Cr(Cr:積
分定数)とし、ステツプS15で燃料噴射時間τを
式K・Cfb・Ue/Neより演算してステツプS3に
戻る。 If the determination in step S12 is that Vs≧V'ref, the zone flag Fzone is determined in step S13 , and if Fzone=1, which is on the rich side, it is determined that the air-fuel ratio is richer than the target value. step
In step S14 , the feedback coefficient Cfb is set to Cfb-Cr (Cr: integral constant) to lean the air-fuel ratio, that is, to reduce the fuel injection amount, and in step S15 , the fuel injection time τ is calculated from the formula K, Cfb, Ue/Ne. Then return to step S3 .
その後、ステツプS15での燃料噴射量の減少に
より第8図に示す如く空燃比がリーン方向に向
い、ステツプS12での判別がVs<V′refとなると、
ステツプS16でゾーンフラグFzoneの判定を行い、
未だFzone=1のリツチ側であるので、次のステ
ツプS17でリーン側デイレイフラグFlが“1”か
否かを判別し、Fl=0のNOのときにはリツチ側
からリーン側へ反転したときと判断してステツプ
S18でデイレイフラグFlを“1”としたのち、ス
テツプS19でデイレイタイマをリセツトする(尚、
このデイレイタイマは上述の基本タイマと同様、
リセツトされた瞬間から時間をアツプカウントす
るタイマである。)そして、Fl=1のYESのデイ
レイ中のときと共に次のステツプS20でデイレイ
タイマが所定のデイレイ時間tdlを経過したか否
かを判別し、経過していないときにはノイズの影
響を防止すべくステツプS14に移りフイードバツ
ク係数CfbをCfb−Crに維持して、ステツプS15で
燃料噴射量を減少したままステツプS3に戻る。一
方、デイレイ時間tdlを経過すると、ステツプS21
でゾーンフラグFzoneを“0”に、かつデイレイ
フラグFlを“0”にしたのち、ステツプS22にお
いて空燃比をリツチ化すべくフイードバツク係数
CfbをCfb+Csl(Csl:比例定数)として、ステツ
プS15で燃料噴射量を増大してステツプS3に戻る。 After that, as the fuel injection amount decreases in step S15 , the air-fuel ratio becomes lean as shown in FIG. 8, and when the determination in step S12 becomes Vs<V'ref,
In step S16 , the zone flag Fzone is determined,
Since it is still on the rich side with Fzone = 1, it is determined in the next step S17 whether the lean side delay flag Fl is "1" or not. Decide and step
After setting the delay flag Fl to "1" in S18 , the delay timer is reset in step S19 (in addition,
This delay timer is similar to the basic timer mentioned above.
This is a timer that counts up the time from the moment it is reset. ) Then, during the delay of YES with Fl=1, in the next step S20 , the delay timer determines whether or not the predetermined delay time tdl has elapsed, and if it has not elapsed, the delay timer determines whether or not the predetermined delay time tdl has elapsed, and if it has not elapsed, the delay timer determines whether or not the predetermined delay time tdl has elapsed. The program moves to step S14 , maintains the feedback coefficient Cfb at Cfb-Cr, and returns to step S3 with the fuel injection amount reduced in step S15 . On the other hand, when the delay time tdl has elapsed, step S21
After setting the zone flag Fzone to "0" and the delay flag Fl to "0", in step S22 , the feedback coefficient is set to enrich the air-fuel ratio.
Cfb is set to Cfb+Csl (Csl: proportionality constant), the fuel injection amount is increased in step S15 , and the process returns to step S3 .
次いで、この燃料噴射量の増大によつても未だ
ステツプS12の判別がVs<V′refであるので、ス
テツプS16でゾーンフラグFzone=0のリーン側
と判定されて、ステツプS23でさらに空燃比をリ
ツチ化すべくフイードバツク係数CfbをCfb+Cl
(Cl:積分定数)とし、ステツプS15でさらに燃料
噴射量を増大してステツプS3に戻る。 Next, even with this increase in the fuel injection amount, the determination in step S12 is still that Vs<V'ref, so in step S16 it is determined that the zone flag Fzone is on the lean side of 0, and in step S23 To enrich the air-fuel ratio, change the feedback coefficient Cfb to Cfb + Cl.
(Cl: integral constant), the fuel injection amount is further increased in step S15 , and the process returns to step S3 .
その後、この燃料噴射量の増大によりステツプ
S12での判別がVs≧V′refとなるが、ステツプS13
での判定がゾーンフラグFzone=0のリーン側で
あるので、ステツプS24でリツチ側デイレイフラ
グFrが“1”が否かを判別し、Fr=0のNOのと
きにはリーン側からリツチ側へ反転したときと判
断してステツプS25でデイレイフラグFrを“1”
にしたのち、ステツプS26でデイレイタイマをリ
セツトする。そして、Fr=1のYESのデイレイ
中のときと共に次のステツプS27でデイレイタイ
マが所定のデイレイ時間tdrを経過したか否かを
判別し、経過していないときにはノイズの影響を
防止すべくステツプS23に移りフイードバツク係
数CfbをCfb+Clに維持して、ステツプS15で燃料
噴射量を増大したままステツプS3に戻る。一方、
デイレイ時間tdrを経過すると、ステツプS28でゾ
ーンフラグFzoneを“1”に、かつデイレイフラ
グFrを“0”にしたのち、ステツプS29において
空燃比をリーン化すべくフイードバツク係数Cfb
をCfb−Csr(Csr:比例定数)として、ステツプ
S15で燃料噴射量を減少してステツプS3に戻る。
その後、ステツプS12の判別がVs≧V′refで、ス
テツプS13での判定がFzone=1となり、以下上
記と同じ動作を繰返すことになる。 After that, this increase in fuel injection amount causes the step
The determination in S 12 is Vs≧V′ref, but step S 13
Since the judgment is on the lean side with the zone flag Fzone = 0, it is determined in step S24 whether the rich side delay flag Fr is "1" or not, and if it is NO with Fr = 0, it is reversed from the lean side to the rich side. Judging that this is the case, set the delay flag Fr to “1” in step S 25 .
After that, the day delay timer is reset in step S26 . Then, during the delay of YES with Fr=1, in the next step S27 , the delay timer determines whether or not a predetermined delay time tdr has elapsed, and if it has not elapsed, a step is executed to prevent the influence of noise. The process moves to S23 , and the feedback coefficient Cfb is maintained at Cfb+Cl, and the process returns to step S3 while increasing the fuel injection amount in step S15 . on the other hand,
When the delay time tdr has elapsed, the zone flag Fzone is set to "1" and the delay flag Fr is set to "0" in step S28 , and then the feedback coefficient Cfb is set in order to make the air-fuel ratio leaner in step S29 .
As Cfb−Csr (Csr: constant of proportionality), step
At S15 , the fuel injection amount is decreased and the process returns to step S3 .
Thereafter, the determination in step S12 is that Vs≧V'ref, and the determination in step S13 is that Fzone=1, and the same operation as above is repeated thereafter.
尚、燃料噴射弁5の噴射タイミングは、第9図
に示すようにイグナイタ14からのイグニツシヨ
ンパルスの立上りによつて上記空燃比コントロー
ラ11のメインフロー中にインタラプトされ、先
ず噴射タイマを燃料噴射時間τにセツトした
(尚、この噴射タイマはセツトされた時間をダウ
ンカウントし、零となつた瞬間に後術の噴射終了
インタラプト信号を発生するカウンタである)の
ち、燃料噴射弁5への電流をONにして燃料噴射
を開始する。そして、燃料噴射の終了は第10図
に示すように上記噴射タイマからの噴射終了イン
タラプト信号によつてインタラプトされ、燃料噴
射弁5への電流をOFFにしてなされる。 The injection timing of the fuel injection valve 5 is interrupted during the main flow of the air-fuel ratio controller 11 by the rise of the ignition pulse from the igniter 14, as shown in FIG. After setting the injection timer to the time τ (note that this injection timer is a counter that counts down the set time and generates a subsequent injection end interrupt signal at the moment it reaches zero), the current to the fuel injection valve 5 is Turn on and start fuel injection. Then, the end of fuel injection is interrupted by the injection end interrupt signal from the injection timer, as shown in FIG. 10, and the current to the fuel injection valve 5 is turned off.
よつて、上記空燃比コントローラ11の作動フ
ローにおいて、ステツプS8により、予め設定され
た混合気の空燃比に対応した空燃比センサ8の目
標値(スライスレベル中央値Vref)を設定する
目標値設定手段15を構成しているとともに、該
目標値設定手段15からの目標値(目標空燃比に
対応したスライスレベル中央値Vref)に応じて
リーン側およびリツチ側の不感帯幅Vhl、Vhrを
変更し、出力勾配が大きい理論空燃比付近である
ときに最大とし、それよりもリーン側およびリツ
チ側に行き出力勾配が小さくなるに従つて小さく
するようにした制御範囲変更手段16を構成して
いる。また、ステツプS12により、空燃比センサ
8の出力(起電力Vs)と目標値設定手段15に
より設定された目標値(スライスレベル中央値
V′ref)とを比較する比較手段17を構成してい
る。さらに、ステツプS13〜S29により、上記比較
手段17の出力を受け、燃料噴射弁5の燃料噴射量
を制御することによりエンジン1に供給する混合
気の空燃比を所定の不感帯幅Vhl、Vhrで上記目
標値に制御する空燃比制御手段18を構成してい
る。 Therefore, in the operation flow of the air-fuel ratio controller 11, in step S8, the target value setting is performed to set the target value (slice level median value Vref) of the air-fuel ratio sensor 8 corresponding to the preset air-fuel ratio of the air-fuel mixture. It constitutes means 15, and changes dead band widths Vhl and Vhr on the lean side and rich side according to the target value (slice level median value Vref corresponding to the target air-fuel ratio) from the target value setting means 15, The control range changing means 16 is configured such that the output gradient is maximized when the output gradient is near the stoichiometric air-fuel ratio, and is made smaller as the output gradient becomes leaner and richer. Further, in step S12 , the output of the air-fuel ratio sensor 8 (electromotive force Vs) and the target value set by the target value setting means 15 (slice level median value
It constitutes a comparison means 17 for comparing with V'ref). Furthermore, in steps S13 to S29 , the air-fuel ratio of the mixture supplied to the engine 1 is adjusted to a predetermined dead band width Vhl, Vhr by receiving the output of the comparison means 17 and controlling the fuel injection amount of the fuel injection valve 5. This constitutes an air-fuel ratio control means 18 that controls the above target value.
したがつて、上記実施例においては、エンジン
1の排気ガス中の酵素濃度に応じてその出力(起
電力)が変化する空燃比センサ8により空燃比が
検出され、該空燃比センサ8の出力と予め設定さ
れた空燃比に対応した空燃比センサ8の目標値
(所定の不感帯幅Vhl、Vhrをもつ)とが比較さ
れて、その偏差に応じて燃料噴射弁5からの燃料
噴射量が制御されることにより、エンジン1に供
給する混合気の空燃比が所定の範囲内にフイード
バツク制御されることになる。 Therefore, in the above embodiment, the air-fuel ratio is detected by the air-fuel ratio sensor 8 whose output (electromotive force) changes depending on the enzyme concentration in the exhaust gas of the engine 1, and the output of the air-fuel ratio sensor 8 and The target value of the air-fuel ratio sensor 8 (having predetermined dead band widths Vhl and Vhr) corresponding to a preset air-fuel ratio is compared, and the amount of fuel injected from the fuel injection valve 5 is controlled according to the deviation. As a result, the air-fuel ratio of the air-fuel mixture supplied to the engine 1 is feedback-controlled within a predetermined range.
この場合、空燃比センサ8の起電力特性は第3
図に示す如くリニアに変化するが、理論空燃比
(A/F=14.7)付近で起電力勾配(傾斜)が最
大で、理論空燃比よりもリーン側およびリツチ側
になるにつれて起電力勾配がゆるやかになる特性
を有する。これに対し、上記空燃比センサ8の起
電力に対するノイズの影響を防止すべく目標空燃
比に対応した空燃比センサ8の目標値(スライス
レベル中央値Vref)に対して不感帯幅Vhl、Vhr
を設けたが、この不感帯幅Vhl、Vhrを制御範囲
変更手段16により上記スライスレベル中央値
Vrefつまり目標空燃比に応じて変更し、目標空
燃比が理論空燃比(A/F=14.7)付近で最大
で、理論空燃比よりもリーン側およびリツチ側に
行くに従つて小さくしたことにより、起電力勾配
の大きい理論空燃比付近では、大きい不感帯幅
Vhl、Vhrによつて空燃比の変動をさほど生じる
ことなく該不感帯幅Vhl、Vhrにより耐ノイズ性
が著しく高められる。一方、理論空燃比よりもリ
ーン側又はリツチ側では、小さい不感帯幅Vhl、
Vhrにより耐ノイズ性をある程度確保しながら、
該不感帯幅Vhl、Vhrによる空燃比の変動を増長
するのが抑制され、空燃比制御の精度が低下する
のが防止されることになる。よつて、空燃比制御
を、その精度の低下を招くことなく耐ノイズを向
上させて、正確にかつ安定して行うことができ
る。 In this case, the electromotive force characteristic of the air-fuel ratio sensor 8 is
As shown in the figure, it changes linearly, but the electromotive force gradient (slope) is maximum near the stoichiometric air-fuel ratio (A/F = 14.7), and becomes gentler as it gets leaner and richer than the stoichiometric air-fuel ratio. It has the characteristics of On the other hand, in order to prevent the influence of noise on the electromotive force of the air-fuel ratio sensor 8, dead band widths Vhl and Vhr are set for the target value (slice level median value Vref) of the air-fuel ratio sensor 8 corresponding to the target air-fuel ratio.
However, the dead band widths Vhl and Vhr are changed to the above-mentioned slice level median value by the control range changing means 16.
Vref, that is, the target air-fuel ratio, is changed according to the target air-fuel ratio, and the target air-fuel ratio is maximum near the stoichiometric air-fuel ratio (A/F = 14.7), and becomes smaller as it goes leaner and richer than the stoichiometric air-fuel ratio. Near the stoichiometric air-fuel ratio where the electromotive force gradient is large, the dead band width is large.
The noise resistance can be significantly improved by the dead band widths Vhl and Vhr without causing much variation in the air-fuel ratio due to Vhl and Vhr. On the other hand, on the lean side or rich side of the stoichiometric air-fuel ratio, the dead band width Vhl is small,
While ensuring a certain degree of noise resistance with VHR,
Increase in fluctuations in the air-fuel ratio due to the dead band widths Vhl and Vhr is suppressed, and a decrease in the accuracy of air-fuel ratio control is prevented. Therefore, the air-fuel ratio control can be performed accurately and stably with improved noise resistance without reducing its accuracy.
尚、上記実施例では、燃料噴射方式においてそ
の燃料噴射量の制御により空燃比制御を行つた
が、気化器方式においてエアブリード量の制御に
より空燃比制御を行うようにしてもよい。 In the above embodiment, the air-fuel ratio is controlled by controlling the fuel injection amount in the fuel injection method, but the air-fuel ratio may be controlled by controlling the air bleed amount in the carburetor method.
(発明の効果)
以上説明したように、本発明によれば、エンジ
ンの排気ガス中の酸素濃度に応じてその出力が変
化しかつ出力値によつて出力勾配が異なる空燃比
センサを用いてエンジンの空燃比を所定範囲の空
燃比にフイードバツク制御する場合、目標空燃比
に対応した空燃比センサの目標値の不感帯幅を空
燃比センサの出力勾配の大小に応じて変更して、
出力勾配が小さいときには大きいときと比較して
小さくするようにしたので、空燃比制御精度の低
下を招くことなく耐ノイズ性を向上させることが
でき、上記空燃比制御を安定して正確に行うこと
ができる。(Effects of the Invention) As explained above, according to the present invention, an air-fuel ratio sensor whose output changes depending on the oxygen concentration in the exhaust gas of the engine and whose output gradient differs depending on the output value is used to When performing feedback control of the air-fuel ratio to an air-fuel ratio within a predetermined range, the dead band width of the target value of the air-fuel ratio sensor corresponding to the target air-fuel ratio is changed according to the magnitude of the output gradient of the air-fuel ratio sensor.
Since the output gradient is made smaller when it is small compared to when it is large, noise resistance can be improved without reducing the accuracy of air-fuel ratio control, and the above-mentioned air-fuel ratio control can be performed stably and accurately. Can be done.
第1図は本発明の構成を示すブロツク図であ
る。第2図〜第10図は本発明の実施例を例示
し、第2図はエンジンの空燃比制御システムの概
略構成図、第3図は空燃比センサの起電力特性を
示す特性図、第4図は空燃比コントローラの作動
を示すフローチヤート図、第5図はデータテーブ
ルの一例を示す図、第6図は空燃比センサの起電
力に対するノイズの影響を示す説明図、第7図は
スライスレベル中央値に対する不感帯幅のマツプ
を示す図、第8図は空燃比センサの出力特性と平
均燃料噴射量との対応関係を示す説明図、第9図
および第10図はそれぞれ燃料噴射開始時および
終了時のインタラプト処理を示す図である。
1……エンジン、3……排気通路、5……燃料
噴射弁、8……空燃比センサ、9……HCセン
サ、10……排気温センサ、11……空燃比コン
トローラ、15……目標値設定手段、16……制
御範囲変更手段、17……比較手段、18……空
燃比制御手段。
FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 10 illustrate embodiments of the present invention, FIG. 2 is a schematic configuration diagram of an engine air-fuel ratio control system, FIG. 3 is a characteristic diagram showing the electromotive force characteristics of the air-fuel ratio sensor, and FIG. Figure 5 is a flowchart showing the operation of the air-fuel ratio controller, Figure 5 is a diagram showing an example of a data table, Figure 6 is an explanatory diagram showing the influence of noise on the electromotive force of the air-fuel ratio sensor, and Figure 7 is the slice level. A diagram showing a map of the dead band width with respect to the median value, Figure 8 is an explanatory diagram showing the correspondence between the output characteristics of the air-fuel ratio sensor and the average fuel injection amount, and Figures 9 and 10 are the graphs at the start and end of fuel injection, respectively. It is a figure which shows interrupt processing at the time. 1... Engine, 3... Exhaust passage, 5... Fuel injection valve, 8... Air-fuel ratio sensor, 9... HC sensor, 10... Exhaust temperature sensor, 11... Air-fuel ratio controller, 15... Target value Setting means, 16... Control range changing means, 17... Comparing means, 18... Air-fuel ratio control means.
Claims (1)
中の酸素濃度に応じてその出力がリニアに変化し
かつ出力値によつて出力勾配が異なる空燃比セン
サと、予め設定された混合気の空燃比に対応した
上記空燃比センサの目標値を設定する目標値設定
手段と、上記空燃比センサの出力と目標値設定手
段により設定された目標値とを比較する比較手段
と、該比較手段の出力を受け、エンジンに供給す
る混合気の空燃比を所定の不感帯幅で上記目標値
に制御する空燃比制御手段と、上記空燃比センサ
からの出力値における出力勾配が小さいときには
大きいときと比較して上記空燃比制御手段の不感
帯幅を小さくするように変更する制御範囲変更手
段とを設けたことを特徴とするエンジンの空燃比
制御装置。1. An air-fuel ratio sensor that is installed in the exhaust passage of the engine and whose output changes linearly according to the oxygen concentration in the exhaust gas, and whose output slope varies depending on the output value, and an air-fuel ratio of the air-fuel mixture that is set in advance. a target value setting means for setting a target value of the air-fuel ratio sensor corresponding to the target value; a comparison means for comparing the output of the air-fuel ratio sensor with the target value set by the target value setting means; air-fuel ratio control means for controlling the air-fuel ratio of the air-fuel mixture supplied to the engine to the target value within a predetermined dead band width; 1. An air-fuel ratio control device for an engine, comprising: control range changing means for changing a dead band width of the air-fuel ratio controlling means to reduce a dead band width of the air-fuel ratio controlling means.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP22613384A JPS61104136A (en) | 1984-10-27 | 1984-10-27 | Control device for air-fuel ratio of engine |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP22613384A JPS61104136A (en) | 1984-10-27 | 1984-10-27 | Control device for air-fuel ratio of engine |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS61104136A JPS61104136A (en) | 1986-05-22 |
JPH0319377B2 true JPH0319377B2 (en) | 1991-03-14 |
Family
ID=16840363
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP22613384A Granted JPS61104136A (en) | 1984-10-27 | 1984-10-27 | Control device for air-fuel ratio of engine |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS61104136A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3813219A1 (en) * | 1988-04-20 | 1989-11-02 | Bosch Gmbh Robert | METHOD AND DEVICE FOR LAMB CONTROL |
-
1984
- 1984-10-27 JP JP22613384A patent/JPS61104136A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS61104136A (en) | 1986-05-22 |
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