JPH0433975B2 - - Google Patents

Info

Publication number
JPH0433975B2
JPH0433975B2 JP21857783A JP21857783A JPH0433975B2 JP H0433975 B2 JPH0433975 B2 JP H0433975B2 JP 21857783 A JP21857783 A JP 21857783A JP 21857783 A JP21857783 A JP 21857783A JP H0433975 B2 JPH0433975 B2 JP H0433975B2
Authority
JP
Japan
Prior art keywords
air
fuel ratio
sensor
signals
signal
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
Application number
JP21857783A
Other languages
Japanese (ja)
Other versions
JPS60111038A (en
Inventor
Toshimi Murai
Hiroyuki Domyo
Kazuhiko Shiratani
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Priority to JP21857783A priority Critical patent/JPS60111038A/en
Publication of JPS60111038A publication Critical patent/JPS60111038A/en
Publication of JPH0433975B2 publication Critical patent/JPH0433975B2/ja
Granted legal-status Critical Current

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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)
    • F02D41/1483—Proportional component
    • 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
    • F02D41/1473—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method
    • F02D41/1474—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method by detecting the commutation time of the sensor

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

【発明の詳細な説明】 技術分野 本発明は内燃機関の空燃比フイードバツク制御
方法に関する。TECHNICAL FIELD The present invention relates to an air-fuel ratio feedback control method for an internal combustion engine.

従来技術 内燃機関の排気系に排気ガス中の特定成分濃度
を検出する濃度センサ、例えば酸素濃度を検出す
る酸素濃度センサ（O2センサ）、と排気ガス中に
含まれるHC，CO，NOx成分を浄化する三元触
媒コンバータとを設け、そのO2センサの検出出
力に基づいて機関に供給する混合気の空燃比をフ
イードバツク制御して触媒コンバータに流入する
排気ガスの空燃比状態を最適値に制御する技術は
良く知られている。Prior art A concentration sensor (O2 sensor) that detects the concentration of a specific component in exhaust gas, such as an oxygen concentration sensor (O 2 sensor) that detects the concentration of oxygen, is installed in the exhaust system of an internal combustion engine, and a sensor that detects HC, CO, and NOx components contained in the exhaust gas. A three-way catalytic converter is installed, and the air-fuel ratio of the air-fuel mixture supplied to the engine is controlled based on the detection output of the O 2 sensor to optimize the air-fuel ratio of the exhaust gas flowing into the catalytic converter. The techniques for doing so are well known.

この種の空燃比制御装置において、機関の気筒
間で混合気の空燃比にバラツキが生ずるとO2セ
ンサの出力信号がその影響を受けてリツチ信号か
らリーン信号あるいはリーン信号からリツチ信号
への切換えが大きく乱れてしまう。その結果、リ
ツチ又はリーンの判定が安定せず制御中心空燃比
がリツチ側あるいはリーン側へシフトしてしま
う。例えば、O2センサの出力がリツチ信号から
リーン信号に切換わると、燃料増量が行われ、空
燃比はリツチ方向へ向うが、気筒間に空燃比のバ
ラツキがあるとO2センサを通過する排気ガスが
一瞬リーンとなることがあり、O2センサがこれ
を検知して瞬間的なリーン信号（リーンスパイ
ク）を発生する。O2センサの出力信号の乱れに
よつて制御中心空燃比がリツチ側あるいはリーン
側にシフトすると三元触媒コンバータの最適浄化
率を得ることができなくなる。 In this type of air-fuel ratio control device, when there are variations in the air-fuel ratio of the air-fuel mixture between cylinders of the engine, the output signal of the O 2 sensor is affected by this and changes from a rich signal to a lean signal or from a lean signal to a rich signal. becomes greatly disturbed. As a result, the rich or lean determination becomes unstable and the control center air-fuel ratio shifts to the rich or lean side. For example, when the output of the O 2 sensor changes from a rich signal to a lean signal, the amount of fuel is increased and the air-fuel ratio becomes richer, but if there is variation in the air-fuel ratio between cylinders, the exhaust gas passing through the O 2 sensor The gas may become lean for a moment, and the O2 sensor detects this and generates a momentary lean signal (lean spike). If the control center air-fuel ratio shifts to the rich side or lean side due to disturbances in the output signal of the O 2 sensor, it becomes impossible to obtain the optimum purification rate of the three-way catalytic converter.

発明の目的 本発明は従来技術の上述の問題点を解決するも
のであり、本発明の目的は、気筒間の空燃比バラ
ツキに基づく制御中心空燃比のずれを抑制し、三
元触媒コンバータの浄化特性の悪化を防止するこ
とにある。Purpose of the Invention The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to suppress deviations in the control center air-fuel ratio due to air-fuel ratio variations between cylinders, and purify a three-way catalytic converter. The purpose is to prevent deterioration of characteristics.

発明の構成 上述の目的を達成する本発明の特徴は、排気ガ
ス中の酸素濃度に応じて互いに異る値を有する二
信号を選択的に発生せしめ、該発生した二信号の
切り換え時点で機関に供給する混合気の空燃比
を、第１の所定量と第２の所定量の和に相当する
所定量だけスキツプ的に急変させるとともに、前
記二信号に応じて前記混合気の空燃比を積分的に
徐々に変化させるようにした空燃比制御方法にお
いて、前記二信号の切り換え時点から、前記空燃
比制御による引き続く前記二信号の切り換えが発
生する時点よりも前の、予め定められた所定期間
が経過した時点で、前記空燃比を第２の所定量だ
け、直前の前記二信号の切り換え時点における空
燃比急変方向とは逆方向にスキツプ的に急変させ
ることにある。Structure of the Invention A feature of the present invention that achieves the above-mentioned object is that two signals having different values are selectively generated depending on the oxygen concentration in the exhaust gas, and the engine is activated at the time of switching between the two generated signals. The air-fuel ratio of the air-fuel mixture to be supplied is suddenly changed by a predetermined amount corresponding to the sum of the first predetermined amount and the second predetermined amount, and the air-fuel ratio of the air-fuel mixture is integrally changed in accordance with the two signals. In the air-fuel ratio control method in which the air-fuel ratio is gradually changed, a predetermined period of time has elapsed from the time when the two signals are switched, and before the time when the subsequent switching of the two signals occurs due to the air-fuel ratio control. At that point, the air-fuel ratio is abruptly changed by a second predetermined amount in a direction opposite to the direction in which the air-fuel ratio abruptly changed at the time of switching of the two signals immediately before.

実施例 以下図面を用いて本発明を詳細に説明する。Example The present invention will be explained in detail below using the drawings.

第１図は本発明の一実施例として内燃機関の電
子制御燃料噴射制御システムを表わしている。エ
アクリーナ１０から吸入された空気は、エアフロ
ーメータ１２、スロツトル弁１４、サージタンク
１６、吸気ポート１８及び吸気弁２０を含む吸気
通路２２を介して機関本体２４の燃焼室２６へ送
られる。混合気が燃焼して生成される排気ガス
は、排気弁２８、排気ポート３０、排気マニホー
ルド３２、及び排気管３４を介して大気へ放出さ
れる。 FIG. 1 shows an electronic fuel injection control system for an internal combustion engine as an embodiment of the present invention. Air taken in from the air cleaner 10 is sent to the combustion chamber 26 of the engine body 24 through an intake passage 22 that includes an air flow meter 12, a throttle valve 14, a surge tank 16, an intake port 18, and an intake valve 20. Exhaust gas generated by combustion of the air-fuel mixture is discharged to the atmosphere through the exhaust valve 28, exhaust port 30, exhaust manifold 32, and exhaust pipe 34.

スロツトル弁１４は運転室内のアクセルペダル
３６に連動する。スロツトル位置センサ３８はス
ロツトル弁１４の開度を検出する。水温センサ４
０は冷却水温度を検出する。排気マニホールド３
２の集合部分に取付けられたO2センサ４２はそ
の部分における排気ガスの酸素濃度を検出する。
クランク角センサ４４は機関本体２４の図示しな
いクランク軸に結合するデイストリビユータ４６
の回転軸４８の回転からクランク軸が所定角度回
転することを検出する。 The throttle valve 14 is linked to an accelerator pedal 36 in the driver's cab. Throttle position sensor 38 detects the opening degree of throttle valve 14. water temperature sensor 4
0 detects the cooling water temperature. Exhaust manifold 3
The O 2 sensor 42 attached to the collecting portion of No. 2 detects the oxygen concentration of the exhaust gas in that portion.
The crank angle sensor 44 is connected to a distributor 46 connected to a crankshaft (not shown) of the engine body 24.
It is detected from the rotation of the rotating shaft 48 that the crankshaft rotates by a predetermined angle.

エアフローメータ１２、スロツトル位置センサ
３８、水温センサ４０，O2センサ４２，クラン
ク角センサ４４の出力は制御回路５０に送り込ま
れる。 Outputs from the air flow meter 12, throttle position sensor 38, water temperature sensor 40, O 2 sensor 42, and crank angle sensor 44 are sent to a control circuit 50.

燃料噴射弁５２は各気筒毎に各吸気ポート１８
の近傍に設けられ、ポンプ５４は燃料タンク５６
からの燃料を燃料通路５８を介して燃料噴射弁５
２に圧送する。制御回路５０は各センサからの入
力信号をパラメータとして燃料噴射量を計算し、
計算した燃料噴射量に対応したパルスス幅の電気
パルスを燃料噴射弁５２へ送る。 The fuel injection valve 52 is connected to each intake port 18 for each cylinder.
The pump 54 is installed near the fuel tank 56.
from the fuel injection valve 5 through the fuel passage 58.
2. The control circuit 50 calculates the fuel injection amount using input signals from each sensor as parameters,
An electric pulse having a pulse width corresponding to the calculated fuel injection amount is sent to the fuel injection valve 52.

第２図は第１図の制御回路５０を詳細に表わし
ている。マイクロプロセツサから成る中央処理装
置（CPU）６０、ランダムアクセスメモリ
（RAM）６２、リードオンリメモリ（ROM）６
４、マルチプレクサ付きアナログ／デジタル
（Ａ／Ｄ）変換器６６、及び入出力（Ｉ／Ｏ）イ
ンタフエース６８はバス７０を介して互いに接続
されている。 FIG. 2 shows the control circuit 50 of FIG. 1 in detail. A central processing unit (CPU) 60 consisting of a microprocessor, a random access memory (RAM) 62, and a read-only memory (ROM) 6
4. An analog/digital (A/D) converter with multiplexer 66 and an input/output (I/O) interface 68 are connected to each other via a bus 70.

エアフローメータ１２、水温センサ４０、及び
O2センサ４２の検出信号はＡ／Ｄ変換器６６へ
送られ、CPU６０からの信号により選択された
チヤネルの検出信号がＡ／Ｄ変換されてRAM６
２に格納される。スロツトル位置センサ３８及び
クランク角センサ４４からの信号はＩ／Ｏインタ
フエース６８を介してCPU６０に取り込まれる。
また、燃料噴射弁５２はCPU６０が算出した燃
料噴射パルス幅に相当するパルス幅を有する駆動
電流をＩ／Ｏインタフエース６８から受け取り開
弁作動する。 Air flow meter 12, water temperature sensor 40, and
The detection signal of the O2 sensor 42 is sent to the A/D converter 66, and the detection signal of the channel selected by the signal from the CPU 60 is A/D converted and sent to the RAM 6.
2. Signals from the throttle position sensor 38 and crank angle sensor 44 are taken into the CPU 60 via an I/O interface 68.
Further, the fuel injection valve 52 receives a drive current having a pulse width corresponding to the fuel injection pulse width calculated by the CPU 60 from the I/O interface 68 and operates to open the valve.

マイクロコンピユータによる燃料噴射パルス幅
τの演算処理については周知であるため、詳しい
説明は省略するが、例えば第３図に概略的に表わ
す如き流れに従つて演算処理が行われる。CPU
６０は、メイン処理ルーチンあるいは所定クラン
ク角度毎もしくは所定時間毎の割込み処理ルーチ
ンにおいて第３図に示す如き演算処理を実行す
る。まずステツプ７０において、回転速度に関す
るデータＮ、吸入空気量に関するデータＱ、水温
による暖機補正係数FTHW、空燃比フイードバ
ツク補正係数FAF、その他の補正係数α，βを
RAM６２から取り込む。回転速度データＮはク
ランク角センサ４４からの信号に基づいて前もつ
て算出されたRAM６２に格納されている。吸入
空気量データＱはＡ／Ｄ変換器６６を介してエア
フローメータ１２から取り込まれRAM６２に格
納されている。暖機補正係数FTHWは水温セン
サ４０からの信号に応じて前もつて算出され、
RAM６２に格納されている。空燃比フイードバ
ツク補正係数FAFは本発明の方法によつて後述
する如く算出されるもので、これもRAM６２に
格納されている。その他の補正係数α及びβは、
例えばスロツトル位置センサ３８からの信号ある
いは図示しない吸気温センサからの信号、バツテ
リ電圧等により決められる補正係数であり、これ
らもRAM６２に格納されている。次のステツプ
７１においては、定数Ｋ、データＮ及びＱから基
本噴射パルス幅τ0が τ0＝Ｋ・Ｑ／Ｎ から算出される。次のステツプ７２では噴射パル
ス幅τが τ＝τ0・FTHW・FAF・α＋β から算出され、次いでステツプ７３において算出
されたτがＩ／Ｏインタフエース６８に出力され
る。 Since the calculation process of the fuel injection pulse width τ by a microcomputer is well known, a detailed explanation will be omitted, but the calculation process is performed according to the flow schematically shown in FIG. 3, for example. CPU
60 executes arithmetic processing as shown in FIG. 3 in the main processing routine or in the interrupt processing routine at every predetermined crank angle or every predetermined time. First, in step 70, data N regarding rotational speed, data Q regarding intake air amount, warm-up correction coefficient FTHW based on water temperature, air-fuel ratio feedback correction coefficient FAF, and other correction coefficients α and β are calculated.
Import from RAM62. The rotational speed data N is calculated in advance based on the signal from the crank angle sensor 44 and is stored in the RAM 62. Intake air amount data Q is taken in from the air flow meter 12 via the A/D converter 66 and stored in the RAM 62. The warm-up correction coefficient FTHW is calculated in advance according to the signal from the water temperature sensor 40,
It is stored in RAM62. The air-fuel ratio feedback correction coefficient FAF is calculated as described later by the method of the present invention, and is also stored in the RAM 62. Other correction coefficients α and β are
For example, it is a correction coefficient determined by a signal from the throttle position sensor 38, a signal from an intake air temperature sensor (not shown), battery voltage, etc., and these are also stored in the RAM 62. In the next step 71, the basic injection pulse width τ 0 is calculated from the constant K, data N and Q as follows: τ 0 =K·Q/N. In the next step 72, the injection pulse width τ is calculated from τ=τ 0 ·FTHW ·FAF ·α+β, and then in step 73 the calculated τ is output to the I/O interface 68.

第４図はメイン処理ルーチンのうち、空燃比フ
イードバツク補正係数FAFを算出するための処
理ルーチン部分を表わしている。まずステツプ８
０では、空燃比のフイードバツク制御（閉ループ
制御）を行うべき条件が成立しているか否かを判
別する。このフイードバツク制御を行うべき条件
とは、機関が始動状態でないこと、暖機運転中で
ないこと、燃料カツト動作中でないこと、全加速
状態でないこと等であり、これらが全て成立した
場合のみ、プログラムは次のステツプ８１へ進
む。上述の条件が成立しない場合、プログラムは
第４図の処理を全て飛び越してメイン処理ルーチ
ンの次の図示しないステツプに進む。従つてこの
場合、空燃比フイードバツク補正係数FAFは変
化せず、固定したままとなり、空燃比の閉ループ
制御が行なわれることとなる。 FIG. 4 shows a part of the main processing routine for calculating the air-fuel ratio feedback correction coefficient FAF. First step 8
0, it is determined whether the conditions for performing air-fuel ratio feedback control (closed loop control) are satisfied. The conditions for performing this feedback control include the engine not being started, not being warmed up, not in fuel cut mode, not fully accelerating, etc. Only when all of these conditions are met, the program can be executed. Proceed to the next step 81. If the above-mentioned conditions are not satisfied, the program skips the entire process of FIG. 4 and proceeds to the next step (not shown) of the main processing routine. Therefore, in this case, the air-fuel ratio feedback correction coefficient FAF does not change and remains fixed, and closed-loop control of the air-fuel ratio is performed.

ステツプ８１ではQ2センサ４２からの信号に
基づいて排気ガスの空燃比状態を検出する。周知
の如く、Q2センサ４２は排気ガス中に余剰の酸
素が存在する場合、即ち空燃比が理論値よりリー
ン側にある場合は低レベルの電圧（リーン信号）
を出力し、酸素があまり存在しない場合、即ち空
燃比が理論値よりリツチ側にある場合は高レベル
の電圧（リツチ信号）を出力する。このQ2セン
サ４２からの電圧がＡ／Ｄ変換されて２進信号と
なつてCPU６０に取り込まれ、ステツプ８１に
おいて比較基準値と比較される。この２進信号が
基準値より小さい場合は空燃比がリーンでありリ
ーン信号がO2センサ４２から出力されていると
判別してプログラムはステツプ８２側へ進む。２
進信号が基準値より大きい場合は空燃比がリツチ
であり、O2センサ４２がリツチ信号を出力して
いると判別し、プログラムはステツプ８３へ進
む。 In step 81, the air-fuel ratio state of the exhaust gas is detected based on the signal from the Q2 sensor 42. As is well known, the Q2 sensor 42 outputs a low level voltage (lean signal) when there is excess oxygen in the exhaust gas, that is, when the air-fuel ratio is leaner than the stoichiometric value.
When there is not much oxygen present, that is, when the air-fuel ratio is richer than the theoretical value, a high level voltage (rich signal) is output. The voltage from the Q 2 sensor 42 is A/D converted into a binary signal and taken into the CPU 60, where it is compared with a comparison reference value in step 81. If this binary signal is smaller than the reference value, it is determined that the air-fuel ratio is lean and a lean signal is being output from the O 2 sensor 42, and the program proceeds to step 82. 2
If the advance signal is larger than the reference value, it is determined that the air-fuel ratio is rich and the O 2 sensor 42 is outputting a rich signal, and the program proceeds to step 83.

ステツプ８２及び８４は、リツチ信号からリー
ン信号に切換わつた際に積分処理中で用いる
FAF0の値をその直前の空燃比フイードバツク補
正係数FAFに一致させるためのものである。 Steps 82 and 84 are used during the integration process when switching from a rich signal to a lean signal.
This is to make the value of FAF 0 match the immediately preceding air-fuel ratio feedback correction coefficient FAF.

次のステツプ８５では、FAF0を一定値KIだけ
増大させる。即ち、リーン信号が出力されている
場合は、燃料噴射量を徐々に増大させるべく積分
処理を行うものである。メイン処理ルーチンが繰
り返して実行されることによりFAF0はKIずつ増
大せしめられる。次のステツプ８６では、リツチ
信号からリーン信号への切換え時点からあらかじ
め定めた回数ｎだけ燃料噴射が行われたか否かを
判別し、噴射回数がｎ未満の場合はステツプ８７
へ、ｎ以上の場合はステツプ８８へそれぞれ進
む。ステツプ８７では空燃比フイードバツク補正
係数FAFがFAF0からあらかじめ定めた値RS1＋
RS2だけスキツプ的に増量した値に設定される。
一方、ステツプ８８では、FAFがRS1だけスキツ
プ的に増量した値に設定される。このように、リ
ツチ信号からリーン信号への切換え時点からｎ回
燃料噴射されるまでは空燃比フイードバツク補正
係数FAFのスキツプ増量がRS1＋RS2であり、そ
の後RS1となる。 In the next step 85, FAF 0 is increased by a constant value KI. That is, when a lean signal is output, an integral process is performed to gradually increase the fuel injection amount. By repeatedly executing the main processing routine, FAF 0 is increased by KI. In the next step 86, it is determined whether or not fuel injection has been performed a predetermined number of times n from the time of switching from the rich signal to the lean signal. If the number of injections is less than n, step 87 is performed.
If the number is n or more, the process advances to step 88. In step 87, the air-fuel ratio feedback correction coefficient FAF is changed from FAF 0 to a predetermined value RS 1 +
It is set to a value that is skipped by RS 2 .
On the other hand, in step 88, FAF is set to a value increased by RS1 in a skip manner. In this way, the skip increase in the air-fuel ratio feedback correction coefficient FAF is RS 1 +RS 2 from the time of switching from the rich signal to the lean signal until the fuel is injected n times, and then becomes RS 1 .

一方、リツチ信号が出力されている場合は、ス
テツプ８１からステツプ８３へ進み、ステツプ８
２及び８４と同様の処理をステツプ８３及び８９
で行う。次いでステツプ９０においてFAF0がKI
だけ減少せしめられ、従つてメイン処理ルーチン
が繰り返して実行されることによりFAF0が徐々
に減少せしめられる（減少方向の積分処理）。ス
テツプ９１では、リーン信号からリツチ信号への
切換え時点からｎ回燃料噴射が行われたか否かを
判別し、ｎ未満の場合はステツプ９２へ、ｎ以上
の場合はステツプ９３へそれぞれ進む。ステツプ
９２では、FAFがFAF0からRS1＋RS2だけスキ
ツプ的に減量した値に設定され、またステツプ９
３ではFAFがFAF0からRS1だけスキツプ的に減
量した値に設定される。 On the other hand, if the rich signal is being output, the process advances from step 81 to step 83, and then to step 83.
Steps 83 and 89 are similar to steps 2 and 84.
Do it with Then in step 90 FAF 0 is KI
Therefore, by repeatedly executing the main processing routine, FAF 0 is gradually reduced (integration processing in the decreasing direction). In step 91, it is determined whether or not fuel injections have been performed n times since the lean signal is switched to the rich signal. If it is less than n, the process proceeds to step 92, and if it is greater than n, the process proceeds to step 93. In step 92, FAF is set to a value that is skipped by RS 1 + RS 2 from FAF 0 , and in step 9
3, FAF is set to a value that is skipped by RS 1 from FAF 0 .

第５図は上述した第４図のフローチヤートによ
つて得られる空燃比フイードバツク補正係数
FAFを表わしている。同図の実線で示すように、
リツチ信号とリーン信号との切換え時点でFAF
はRS1＋RS2だけスキツプし、このスキツプ量は
切換え時点から燃料噴射がｎ回行われるまで維持
され、ｎ回以上となるとスキツプ量はRS1とな
る。即ち、切換わつた時最初は大きなスキツプ量
（RS1＋RS2）であり、後にスキツプ量が通常の
値RS1となる。従来技術によると、同図の破線で
示すように、スキツプ量は常にRS1であつたため
気筒間の空燃比のバラツキがそのままO2センサ
の検出信号に現われてしまい制御中心空燃比のず
れを引き起していたのである。本発明によれば切
換え時点でのスキツプ量が大きいため、気筒間の
空燃比のバラツキが生じてもO2センサがこれに
応答せず、従つてO2センサの検出信号が安定化
する。その結果、フイードバツクにより制御空燃
比が安定化し、三元触媒コンバータの浄化性能の
向上が図れる。逆に、浄化性能の悪化を招くこと
なく触媒コンバータのコストダウンを図ることが
できる。さらに、O2センサの応答速度が向上す
るためフイードバツク制御周波数が上り、より狭
い空燃比幅に空燃比制御を行うことが可能とな
る。 Figure 5 shows the air-fuel ratio feedback correction coefficient obtained by the flowchart in Figure 4 above.
It represents FAF. As shown by the solid line in the same figure,
FAF at the time of switching between rich signal and lean signal
skips by RS 1 +RS 2 , and this skip amount is maintained from the time of switching until fuel injection is performed n times, and when the fuel injection is n times or more, the skip amount becomes RS 1 . That is, at the time of switching, the skip amount is initially large (RS 1 +RS 2 ), and later the skip amount becomes the normal value RS 1 . According to the conventional technology, as shown by the broken line in the figure, the skip amount was always RS 1 , so the variation in the air-fuel ratio between cylinders was directly reflected in the detection signal of the O 2 sensor, causing a deviation in the control center air-fuel ratio. It was happening. According to the present invention, since the skip amount at the time of switching is large, even if the air-fuel ratio varies between cylinders, the O 2 sensor does not respond to this, and the detection signal of the O 2 sensor is therefore stabilized. As a result, the control air-fuel ratio is stabilized by feedback, and the purification performance of the three-way catalytic converter can be improved. Conversely, it is possible to reduce the cost of the catalytic converter without deteriorating the purification performance. Furthermore, since the response speed of the O 2 sensor improves, the feedback control frequency increases, making it possible to control the air-fuel ratio within a narrower air-fuel ratio range.

第６図はO2センサの検出信号の波形図であり、
(A)は気筒間に空燃比バラツキがあるときの従来の
検出信号であり、ａの部分がリーンスパイクであ
る。(B)はバラツキのないときの従来の検出信号、
(C)は本発明における検出信号をそれぞれ示してい
る。本発明によれば、切換え時点でのスキツプ量
が大きいため、O2センサの検出信号の立上り、
立下りが速くなつていることが同図からも明らか
である。 Figure 6 is a waveform diagram of the detection signal of the O 2 sensor,
(A) is a conventional detection signal when there is an air-fuel ratio variation between cylinders, and the portion a is a lean spike. (B) is the conventional detection signal when there is no variation;
(C) shows detection signals in the present invention. According to the present invention, since the skip amount at the time of switching is large, the rise of the detection signal of the O 2 sensor,
It is clear from the figure that the fall is becoming faster.

なお、リツチ信号とリーン信号との切換え時点
から次の切換え時点までスキツプ量を大きな値に
維持してもリーンスパイイクを除去できるが、こ
れによると、空燃比制御周期が短かくなり、また
空燃比の急激な変化を引き起すため、機関回転速
度の変動、エミツシヨンの悪化等を起す等の不都
合が生じる。 Note that lean spikes can be removed by maintaining the skip amount at a large value from the point of switching between the rich signal and the lean signal to the next point of switching, but this shortens the air-fuel ratio control cycle and increases the Since this causes a sudden change in the fuel ratio, problems such as fluctuations in engine speed and deterioration of emission occur.

発明の効果 以上詳細に説明したように本発明によれば、気
筒間空燃比バラツキによるO2センサの出力信号
の乱れをフイードバツク制御反転時に安定化され
るので制御中心空燃比のずれが抑制せしめられ
る。また、O2センサ出力信号の乱れに対し最小
限の空燃比変化に抑制するため、ドライバビリテ
イーの悪化を招くことがない。Effects of the Invention As described in detail above, according to the present invention, the disturbance in the output signal of the O 2 sensor due to the air-fuel ratio variation among the cylinders is stabilized when the feedback control is reversed, so that the shift in the control center air-fuel ratio is suppressed. . Additionally, since the air-fuel ratio change is suppressed to the minimum due to disturbances in the O 2 sensor output signal, drivability does not deteriorate.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の一実施例の全体構成図、第２
図は第１図の制御回路を詳細に表わすブロツク
図、第３図及び第４図は第１図の実施例における
制御プログラムの一部のフローチヤート、第５図
は空燃比フイードバツク補正係数FAFの変化を
表わす図、第６図はO2センサの検出信号波形図
である。 ４２…O2センサ、５０…制御回路、５２…燃
料噴射弁、６０…CPU、６２…RAM、６４…
ROM。 Fig. 1 is an overall configuration diagram of an embodiment of the present invention, Fig. 2
The figure is a block diagram showing the control circuit of Fig. 1 in detail, Figs. 3 and 4 are flowcharts of part of the control program in the embodiment of Fig. 1, and Fig. 5 is a block diagram showing the control circuit of Fig. 1 in detail. FIG. 6, a diagram showing the changes, is a detection signal waveform diagram of the O 2 sensor. 42... O2 sensor, 50...control circuit, 52...fuel injection valve, 60...CPU, 62...RAM, 64...
ROM.

Claims (1)

【特許請求の範囲】 １ 排気ガス中の酸素濃度に応じて互いに異る値
を有する二信号を選択的に発生せしめ、該発生し
た二信号の切り換え時点で機関に供給する混合気
の空燃比を、第１の所定量と第２の所定量の和に
相当する所定量だけスキツプ的に急変させるとと
もに、前記二信号に応じて前記混合気の空燃比を
積分的に徐々に変化させるようにした空燃比制御
方法において、 前記二信号の切り換え時点から、前記空燃比制
御による引き続く前記二信号の切り換えが発生す
る時点よりも前の、予め定められた所定期間が経
過した時点で、前記空燃比を第２の所定量だけ、
直前の前記二信号の切り換え時点における空燃比
急変方向とは逆方向にスキツプ的に急変させるこ
とを特徴とする内燃機関の空燃比制御方法。[Claims] 1. Two signals having different values are selectively generated depending on the oxygen concentration in exhaust gas, and the air-fuel ratio of the air-fuel mixture supplied to the engine is determined at the time of switching between the two generated signals. , the air-fuel ratio of the mixture is changed suddenly in a skip manner by a predetermined amount corresponding to the sum of the first predetermined amount and the second predetermined amount, and the air-fuel ratio of the mixture is gradually changed in an integral manner in accordance with the two signals. In the air-fuel ratio control method, the air-fuel ratio is adjusted after a predetermined period has elapsed from the time when the two signals are switched and before the time when the two signals are subsequently switched by the air-fuel ratio control. only a second predetermined amount;
An air-fuel ratio control method for an internal combustion engine, characterized in that the air-fuel ratio is suddenly changed in a skip manner in a direction opposite to the air-fuel ratio sudden change direction at the time of switching of the two signals immediately before.
JP21857783A 1983-11-22 1983-11-22 Air-fuel ratio control method of internal-combustion engine Granted JPS60111038A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP21857783A JPS60111038A (en) 1983-11-22 1983-11-22 Air-fuel ratio control method of internal-combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP21857783A JPS60111038A (en) 1983-11-22 1983-11-22 Air-fuel ratio control method of internal-combustion engine

Publications (2)

Publication Number Publication Date
JPS60111038A JPS60111038A (en) 1985-06-17
JPH0433975B2 true JPH0433975B2 (en) 1992-06-04

Family

ID=16722124

Family Applications (1)

Application Number Title Priority Date Filing Date
JP21857783A Granted JPS60111038A (en) 1983-11-22 1983-11-22 Air-fuel ratio control method of internal-combustion engine

Country Status (1)

Country Link
JP (1) JPS60111038A (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3718720A1 (en) * 1987-06-04 1988-12-22 Vdo Schindling METHOD FOR REGULATING THE FUEL-AIR RATIO OF AN INTERNAL COMBUSTION ENGINE
JPH029926A (en) * 1988-06-27 1990-01-12 Daihatsu Motor Co Ltd Air-fuel ratio controller for internal combustion engine

Also Published As

Publication number Publication date
JPS60111038A (en) 1985-06-17

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