JP2600824B2 - Air-fuel ratio control device for internal combustion engine - Google Patents
Air-fuel ratio control device for internal combustion engineInfo
- Publication number
- JP2600824B2 JP2600824B2 JP17736588A JP17736588A JP2600824B2 JP 2600824 B2 JP2600824 B2 JP 2600824B2 JP 17736588 A JP17736588 A JP 17736588A JP 17736588 A JP17736588 A JP 17736588A JP 2600824 B2 JP2600824 B2 JP 2600824B2
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- fuel
- oxygen concentration
- sensor
- 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.)
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- 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］ この発明は内燃機関の排ガス中の酸素濃度を酸素濃度
センサ（以下、O2センサという）によって検出し、この
検出値に基いて内燃機関に供給する混合気の空燃比を、
例えば理論空燃比付近にフィードバック制御する内燃機
関の空燃比制御装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention detects an oxygen concentration in exhaust gas of an internal combustion engine by an oxygen concentration sensor (hereinafter, referred to as an O 2 sensor), and outputs the detected value to the internal combustion engine based on the detected value. The air-fuel ratio of the air-fuel mixture
For example, the present invention relates to an air-fuel ratio control device for an internal combustion engine that performs feedback control near a stoichiometric air-fuel ratio.
［従来の技術］ 従来、排気系に設置したO2センサの空燃比に対する出
力特性を考慮して、O2センサ出力電圧に対応した時定数
でO2センサ出力を積分し、この積分出力で燃料量を補正
するようにすることで、理論空燃比より実際の空燃比が
大きくずれているときには燃料量が急速に修正され、
又、理論空燃比に実際の空燃比が近づいたときには燃料
量がゆるやかに修正されるようにした技術が知られてい
る（特開昭51−140021号公報参照）。[Prior Art] Conventionally, in view of the output characteristics with respect to the air-fuel ratio of the O 2 sensor disposed in an exhaust system, by integrating the O 2 sensor output with a time constant corresponding to the O 2 sensor output voltage, the fuel in the integration output By correcting the amount, when the actual air-fuel ratio is greatly deviated from the stoichiometric air-fuel ratio, the fuel amount is quickly corrected,
There is also known a technique in which the fuel amount is gradually corrected when the actual air-fuel ratio approaches the stoichiometric air-fuel ratio (see JP-A-51-140021).
［発明が解決しようとする課題］ ところが、このフィードバック制御においても、イン
ジェクタが燃料を噴射してから燃焼してO2センサにて酸
素濃度が検出されるまでのガス遅れ時間があり、この遅
れ時間を充分に補償できないため、空燃比補正制御の応
答性が低く、特に加速時のように実際の空燃比が急激に
変化する場合、空燃比補正量の追い掛けが遅くなって、
空燃比制御量を瞬時に補正することができず、エミッシ
ョン悪化域が広くなるという問題点がある。[Problems to be Solved] However, even in this feedback control, there is a gas delay time to burn from the injector is injecting fuel in O 2 sensor to the oxygen concentration is detected, the delay time Can not be sufficiently compensated, the response of the air-fuel ratio correction control is low, especially when the actual air-fuel ratio changes rapidly, such as during acceleration, the chase of the air-fuel ratio correction amount becomes slow,
There is a problem that the air-fuel ratio control amount cannot be corrected instantaneously, and the emission deterioration range becomes wide.
この発明は上記問題点を解決するためになされたもの
であって、その目的はガス遅れ時間を考慮し、空燃比補
正制御の応答性を高めてエミッションを向上することが
できる内燃機関の空燃比制御装置を提供することにあ
る。SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an air-fuel ratio of an internal combustion engine that can improve emission by improving responsiveness of air-fuel ratio correction control in consideration of a gas delay time. It is to provide a control device.
［課題を解決するための手段］ この発明は上記目的を達成するため、第１図に示すよ
うに、内燃機関の排気系に設けられ、かつ、内燃機関の
排ガス中の酸素濃度を検出して機関に供給された混合気
の実空燃比に応じた信号を出力する酸素濃度センサと、
前記酸素濃度センサの出力信号に基いて、所望の目標空
燃比と前記実空燃比との空燃比偏差を検出する空燃比偏
差検出手段と、前記酸素濃度センサの実空燃比に応じた
出力信号の変化分が正から負、又は負から正に反転変化
したことを検出する反転検出手段と、前記空燃比偏差検
出手段にて検出された前記空燃比偏差に対応して空燃比
制御量を設定するとともに、前記反転検出手段にて前記
反転変化が検出されたとき、前記空燃比制御量を前記実
空燃比が前記目標空燃比に近づく側に所定量変化させる
空燃比制御量設定手段と、前記空燃比制御量設定手段に
て設定された前記空燃比制御量に基いて機関に供給され
る混合気の空燃比を制御する空燃比制御手段とを備えた
内燃機関の空燃比制御装置をその要旨とする。[Means for Solving the Problems] In order to achieve the above object, the present invention is provided in an exhaust system of an internal combustion engine as shown in FIG. 1 and detects oxygen concentration in exhaust gas of the internal combustion engine. An oxygen concentration sensor that outputs a signal corresponding to the actual air-fuel ratio of the air-fuel mixture supplied to the engine,
Air-fuel ratio deviation detection means for detecting an air-fuel ratio deviation between a desired target air-fuel ratio and the actual air-fuel ratio based on the output signal of the oxygen concentration sensor; and an output signal of the oxygen concentration sensor according to the actual air-fuel ratio. Inversion detection means for detecting that the change has changed from positive to negative, or from negative to positive, and an air-fuel ratio control amount is set corresponding to the air-fuel ratio deviation detected by the air-fuel ratio deviation detection means. An air-fuel ratio control amount setting unit configured to change the air-fuel ratio control amount by a predetermined amount toward the side where the actual air-fuel ratio approaches the target air-fuel ratio when the inversion change is detected by the inversion detection unit; An air-fuel ratio control device for an internal combustion engine including air-fuel ratio control means for controlling an air-fuel ratio of an air-fuel mixture supplied to an engine based on the air-fuel ratio control amount set by a fuel ratio control amount setting means. I do.
ここで、前記空燃比偏差検出手段を、混合気の空燃比
に対する酸素濃度センサの出力特性に基いて、目標空燃
比と該混合気の空燃比との空燃比偏差と、酸素濃度セン
サの出力信号との関係を予め記憶しておく記憶手段と、
前記記憶手段に記憶しておいた前記関係を用いて、前記
酸素濃度センサの出力信号に対応して前記空燃比偏差を
読み出す空燃比偏差検出手段とを含むものとするのがよ
い。Here, the air-fuel ratio deviation detecting means detects the air-fuel ratio deviation between the target air-fuel ratio and the air-fuel ratio of the air-fuel mixture based on the output characteristics of the oxygen concentration sensor with respect to the air-fuel ratio of the air-fuel mixture, and the output signal of the oxygen concentration sensor. Storage means for storing in advance the relationship with
An air-fuel ratio deviation detecting means for reading out the air-fuel ratio deviation in response to the output signal of the oxygen concentration sensor using the relation stored in the storage means may be included.
［作用］ 上記空燃比制御装置の構成によれば、酸素濃度センサ
により内燃機関に供給された混合気の実空燃比に応じた
信号が出力されると、その信号に対応して空燃比偏差検
出手段により所望の目標空燃比と混合気の実空燃比との
空燃比偏差が求められる。[Operation] According to the configuration of the air-fuel ratio control device, when a signal corresponding to the actual air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine is output from the oxygen concentration sensor, the air-fuel ratio deviation detection is performed in accordance with the signal. The means determines an air-fuel ratio deviation between the desired target air-fuel ratio and the actual air-fuel ratio of the air-fuel mixture.
空燃比制御量設定手段はこの空燃比偏差に対応して空
燃比制御量を設定するとともに、反転検出手段により酸
素濃度センサの出力信号の変化分が正から負、又は負か
ら正に反転変化したことが検出されると、前記空燃比制
御量を実空燃比が目標空燃比に近づく側に所定量変化さ
せる。そして、空燃比制御手段は空燃比制御量設定手段
により設定された空燃比制御量に基いて機関に供給され
る混合気の空燃比を制御する。The air-fuel ratio control amount setting means sets the air-fuel ratio control amount in accordance with the air-fuel ratio deviation, and the change in the output signal of the oxygen concentration sensor has changed from positive to negative or from negative to positive by the inversion detecting means. When this is detected, the air-fuel ratio control amount is changed by a predetermined amount to the side where the actual air-fuel ratio approaches the target air-fuel ratio. The air-fuel ratio control means controls the air-fuel ratio of the air-fuel mixture supplied to the engine based on the air-fuel ratio control amount set by the air-fuel ratio control amount setting means.
又、前記空燃比偏差検出手段を、混合気の空燃比に対
する酸素濃度センサの出力特性に基いて、目標空燃比と
該混合気の空燃比との空燃比偏差と酸素濃度センサの出
力信号との関係を予め記憶しておく記憶手段と、前記記
憶手段に記憶しておいた前記関係を用いて、前記酸素濃
度センサの出力信号に対応して前記空燃比偏差を読み出
す空燃比偏差読出手段とを含むものとすることにより、
酸素濃度センサの出力信号に対応して空燃比偏差読出手
段により記憶手段から空燃比偏差が読み出され、その読
み出された空燃比偏差が空燃比制御量設定手段に出力さ
れる。The air-fuel ratio deviation detecting means may be configured to calculate an air-fuel ratio deviation between the target air-fuel ratio and the air-fuel ratio of the air-fuel mixture based on an output characteristic of the oxygen concentration sensor with respect to the air-fuel ratio of the air-fuel mixture. A storage unit that stores the relationship in advance, and an air-fuel ratio deviation reading unit that reads the air-fuel ratio deviation in response to the output signal of the oxygen concentration sensor using the relationship stored in the storage unit. By including
The air-fuel ratio deviation is read from the storage unit by the air-fuel ratio deviation reading unit in accordance with the output signal of the oxygen concentration sensor, and the read air-fuel ratio deviation is output to the air-fuel ratio control amount setting unit.
［実施例］ 以下、この発明を具体化した一実施例を第２〜８図に
従って説明する。[Embodiment] An embodiment of the present invention will be described below with reference to FIGS.
第２図は本実施例の空燃比制御装置が搭載された車両
用内燃機関（以下、エンジンという）及びその周辺装置
を示す概略系統図である。FIG. 2 is a schematic system diagram showing a vehicle internal combustion engine (hereinafter, referred to as an engine) on which the air-fuel ratio control device of the present embodiment is mounted and peripheral devices thereof.
エンジン１は大気より空気を吸入するとともに燃料噴
射弁２により噴射される燃料と空気とを混合して吸気ポ
ート３に導く吸気系４と、点火プラグ５にて点火された
混合気の燃焼エネルギをピストン６を介して回転運動と
して取り出す燃焼室７と、燃焼後のガスを排気ポート８
を介して排出する排気系９とを備えている。The engine 1 sucks air from the atmosphere and mixes fuel and air injected by a fuel injection valve 2 to guide the air to an intake port 3, and the combustion energy of the air-fuel mixture ignited by a spark plug 5. A combustion chamber 7 which is taken out as a rotary motion via a piston 6 and an exhaust port 8
And an exhaust system 9 for exhausting the air through the exhaust system.
吸気系４は、大気を取入れるエアクリーナ（図示
略）、吸入空気量を制御するスロットルバルブ10、吸入
空気の脈動を平滑化するサージタンク11等により構成さ
れ、サージタンク11には吸気管負圧を検出する吸気圧セ
ンサ12が設けられている。吸入空気量は、図示しないア
クセルペダルに連動したスロットルバルブ10の開度によ
って制御される。なお、吸気系４には吸気圧センサ12の
他に、前記スロットルバルブ10の開度に応じた信号を出
力する開度センサ13a（第３図参照）と、エンジン１の
アイドリング時にオン状態となるアイドルスイッチ13b
（第３図参照）とを備えたスロットルポジションセンサ
13や、吸気温センサ14等が設けられている。The intake system 4 includes an air cleaner (not shown) that takes in the atmosphere, a throttle valve 10 that controls the amount of intake air, a surge tank 11 that smoothes the pulsation of the intake air, and the like. Is provided. The intake air amount is controlled by the opening of the throttle valve 10 linked to an accelerator pedal (not shown). The intake system 4 has an opening sensor 13a (see FIG. 3) that outputs a signal corresponding to the opening of the throttle valve 10 in addition to the intake pressure sensor 12, and is turned on when the engine 1 is idling. Idle switch 13b
(See FIG. 3)
13 and an intake air temperature sensor 14 are provided.
前記排気系９には、排気中の酸素濃度を検出する起電
力型の酸素濃度センサ（以下、O2センサという）15が設
けられている。又、前記エンジン１の各気筒に設けられ
た点火プラグ５は、図示しないクランク軸の回転に同期
してイグナイタ16にて生成される高電圧を配電するディ
ストリビュータ17に接続されている。このディストリビ
ュータ17には、エンジン１の回転数NEに応じたパルスを
発生する回転数センサ18と、気筒判別センサ19とが設け
られている。なお、エンジン１のシリンダブロック1a
は、循環する冷却水によって冷却されており、エンジン
１の運転状態のひとつであるこの冷却水の温度は、シリ
ンダブロック1aに設けられた冷却水温センサ20により検
出される。The exhaust system 9 is provided with an electromotive force type oxygen concentration sensor (hereinafter referred to as an O 2 sensor) 15 for detecting the oxygen concentration in the exhaust gas. The ignition plug 5 provided in each cylinder of the engine 1 is connected to a distributor 17 that distributes a high voltage generated by an igniter 16 in synchronization with rotation of a crankshaft (not shown). The distributor 17 is provided with a rotation speed sensor 18 that generates a pulse corresponding to the rotation speed NE of the engine 1 and a cylinder discrimination sensor 19. The cylinder block 1a of the engine 1
Is cooled by circulating cooling water, and the temperature of the cooling water, which is one of the operating states of the engine 1, is detected by a cooling water temperature sensor 20 provided in the cylinder block 1a.
エンジン１の運転状態を検出する上記各センサ信号
は、電子制御回路（以下、ECUという）21に入力され、
前記燃料噴射弁２の燃料噴射量制御、点火プラグ５の点
火時期制御等に用いられる。ECU21は、第３図に示すよ
うに、中央処理装置（CPU）22a,リードオンリメモリ（R
OM）22b,ランダムアクセスメモリ（RAM）22c等を内蔵し
たワンチップマイクロコンピュータ22を中心に構成され
ている。このマイクロコンピュータ22の入出力ポートに
は、前記回転数センサ18、気筒判別センサ19、イグナイ
タ16が直接接続されるとともに、マイクロコンピュータ
22内部のA/D変換入力回路23と、バッテリ24を電源とし
て前記O2センサ15のヒータ15bに通電する電力を制御す
るヒータ通電制御回路25と、燃料噴射弁２を駆動する駆
動回路26とが接続されている。Each of the sensor signals for detecting the operating state of the engine 1 is input to an electronic control circuit (hereinafter referred to as an ECU) 21.
It is used for controlling the fuel injection amount of the fuel injection valve 2, controlling the ignition timing of the ignition plug 5, and the like. As shown in FIG. 3, the ECU 21 includes a central processing unit (CPU) 22a and a read-only memory (R).
OM) 22b, a one-chip microcomputer 22 with a built-in random access memory (RAM) 22c, and the like. The input / output port of the microcomputer 22 is directly connected to the rotation speed sensor 18, the cylinder discrimination sensor 19, and the igniter 16, and
22 and the interior of the A / D conversion input circuit 23, a heater conduction control circuit 25 for controlling the power distributed to the heater 15b of the O 2 sensor 15 the battery 24 as a power source, a driving circuit 26 for driving the fuel injection valve 2 Is connected.
A/D変換入力回路23には、吸気圧センサ12、スロット
ルポジションセンサ13の開度センサ13a、吸気温センサ1
4、冷却水温センサ20等のアナログ信号を出力するセン
サが接続されている。従って、CPU22aはエンジン１の運
転状態を反映した種々のパラメータをA/D変換入力回路2
3を介して読み込み、逐次知ることができる。又、このA
/D変換入力回路23には、O2センサ15のヒータ15bに電圧
を印加するヒータ通電制御回路25の出力、電流検出用抵
抗器28の端子電圧の出力及び検出素子15aの出力端子が
接続されており、ヒータ15bの印加電圧、検出素子15aで
発生する起電力及びヒータ15bに流れる電流を検出する
ことができる。The A / D conversion input circuit 23 has an intake pressure sensor 12, an opening sensor 13a of a throttle position sensor 13, an intake temperature sensor 1
4. A sensor that outputs an analog signal, such as the cooling water temperature sensor 20, is connected. Accordingly, the CPU 22a sends various parameters reflecting the operating state of the engine 1 to the A / D conversion input circuit 2
You can read through 3 and know sequentially. Also this A
The / D conversion input circuit 23, the output of the heater conduction control circuit 25 for applying a voltage to the heater 15b of the O 2 sensor 15, an output terminal of the output and detector element 15a of the terminal voltage of the current detecting resistor 28 is connected Thus, the voltage applied to the heater 15b, the electromotive force generated by the detection element 15a, and the current flowing through the heater 15b can be detected.
一方、マイクロコンピュータ22は、直接イグナイタ16
に駆動信号を出力したり、駆動回路26を介して燃料噴射
弁２に制御信号を出力するなどして、これらのアクチュ
エータを駆動する。On the other hand, the microcomputer 22 is directly connected to the igniter 16.
These actuators are driven by outputting a drive signal to the fuel injection valve 2 or a control signal to the fuel injection valve 2 via the drive circuit 26.
このように構成した本実施例のECU21においては、エ
ンジン１の運転状態を読み込んで種々の制御処理を実行
するが、燃料噴射量制御、空燃比制御等に用いるため、
エンジン１の排気中の酸素濃度の検出を行い、その検出
結果に基いて空燃比補正係数の算出を行うようになって
いる。In the ECU 21 of the present embodiment configured as described above, the operating state of the engine 1 is read and various control processes are executed. However, since the ECU 21 is used for fuel injection amount control, air-fuel ratio control, and the like,
The oxygen concentration in the exhaust gas of the engine 1 is detected, and the air-fuel ratio correction coefficient is calculated based on the detection result.
次に、このECU21により実行される空燃比補正係数算
出処理を第４図に示すフローチャートに基いて説明す
る。Next, the air-fuel ratio correction coefficient calculation process executed by the ECU 21 will be described with reference to the flowchart shown in FIG.
この制御処理は所定時間（この実施例では数ms）毎に
実行されるものであり、まず、ステップ100にて今回のO
2センサ15の検出素子15aの出力電圧OXを読み込み、次の
ステップ101ではO2センサ15の検出素子15aの出力信号の
変化分、即ち、今回の出力電圧OXと前回の出力電圧OXO
との差分値DOX（この差分値DOXは非常に短時間における
ものであるため、以下では微分値DOXという。）を求
め、ステップ102に進む。This control processing is executed at predetermined time intervals (several ms in this embodiment).
Reading the output voltage OX of the detection element 15a of the second sensor 15, the change in the output signal of the detection element 15a of the next step 101 the O 2 sensor 15, i.e., the current output voltage OX and the previous output voltage OXO
(Differential value DOX is a very short time, hereinafter, referred to as differential value DOX), and the process proceeds to step 102.
ステップ102では上記ステップ101で求まった今回の微
分値DOXが「０」であるか否かを判定し、「０」以上で
あると判定すると、ステップ103に進む。このステップ1
03では前回の本処理におけるステップ101で求めた前回
の微分値DOXが「０」以上であるか否かを判定し、
「０」以上であると判定する、即ち、O2センサ15の出力
電圧の微分値が正のままであると判定すると、ステップ
104に進んで第５図（ｂ）に示すROM22b内に記憶したマ
ップより目標空燃比（理論空燃比）に対する実空燃比の
空燃比偏差Δλを、O2センサ15の検出素子15aの出力電
圧OXに基いて算出する。なお、第５図（ｂ）に示すマッ
プは第５図（ａ）に示すO2センサ出力と空燃比との関係
を反転して得たものである。In step 102, it is determined whether or not the current differential value DOX obtained in step 101 is “0”. If it is determined that it is “0” or more, the process proceeds to step 103. This step 1
In 03, it is determined whether or not the previous differential value DOX obtained in step 101 in the previous main processing is "0" or more,
If it is determined that the differential value of the output voltage of the O 2 sensor 15 is still positive, the step
The willing air-fuel ratio difference Δλ of the actual air-fuel ratio with respect to FIG. 5 (b) to show the target air-fuel ratio from the map stored in the ROM 22b (stoichiometric air-fuel ratio) in 104, the output voltage of the detection element 15a of the O 2 sensor 15 OX Calculated based on The map shown in FIG. 5B is obtained by inverting the relationship between the O 2 sensor output and the air-fuel ratio shown in FIG. 5A.
続くステップ105ではROM22b内に記憶した第６図
（ａ）に示す比例値マップ及び第６図（ｂ）に示す積分
値マップよりそれぞれ比例補正値PR及び積分補正値INを
求める。そして、ステップ106に進んでRAM22c記憶して
いる前回の空燃比補正係数FAFに前記ステップ105で求め
た比例補正値PR及び積分補正値INを加算するとともに、
前回の比例補正値PROを減算して今回の空燃比補正係数F
AFを算出した後、ステップ107にて前記ステップ105で求
めた比例補正値PRを次回の処理に備えてPROとしてRAM22
c内に記憶させる。そして、ステップ108に進んで前記ス
テップ100にて読み込んだ出力電圧OXを次回のルーチン
で使用する前回の出力電圧OXOとしてRAM22c内に記憶さ
せる。In the subsequent step 105, a proportional correction value PR and an integral correction value IN are obtained from the proportional value map shown in FIG. 6A and the integral value map shown in FIG. 6B stored in the ROM 22b. Then, proceeding to step 106, the proportional correction value PR and the integral correction value IN obtained in step 105 are added to the previous air-fuel ratio correction coefficient FAF stored in the RAM 22c,
Subtract the previous proportional correction value PRO and subtract the current air-fuel ratio correction coefficient F
After calculating the AF, in step 107 the proportional correction value PR obtained in step 105 is used as the PRO for RAM 22 in preparation for the next processing.
Store it in c. Then, the process proceeds to step 108, where the output voltage OX read in step 100 is stored in the RAM 22c as the previous output voltage OXO used in the next routine.
一方、前記ステップ103で前回の微分値DOXが「０」未
満である、即ち、O2センサ15の出力電圧の微分値が負か
ら正に反転変化したと判定すると、ステップ109に移行
して前回の空燃比補正係数FAFから所定のスキップＫ
（正の値）を減じて今回の空燃比補正係数FAFを算出
し、次回のルーチンで使用する前回の空燃比補正係数FA
FとしてRAM22c内に記憶させる。Meanwhile, in step 103 the previous differential value DOX is smaller than "0", i.e., when it is determined that the differential value of the output voltage of the O 2 sensor 15 is positively inverted changes from negative, the process proceeds to step 109 previous Predetermined skip K from the air-fuel ratio correction coefficient FAF
(Positive value) is subtracted to calculate the current air-fuel ratio correction coefficient FAF, which is used in the next routine.
It is stored as F in the RAM 22c.
又、前記ステップ102で今回の微分値DOXが「０」未満
であると判定すると、ステップ110に移行して前回の微
分値DOXが「０」未満であるか否かを判定する。このス
テップ110において「０」未満であると判定する、即
ち、O2センサ15の出力電圧の微分値が負のままであると
判定すると、前記ステップ104以降の処理を実行する。
又、ステップ110で「０」以上であると判定する、即
ち、O2センサ15の出力電圧の微分値が正から負に反転変
化したと判定すると、ステップ111に進んで前回の空燃
比補正係数FAFに所定のスキップＫ（正の値）を加えて
今回の空燃比補正係数FAFを算出し、次回のルーチンで
使用する前回の空燃比補正係数FAFとしてRAM22c内に記
憶させる。If it is determined in step 102 that the current differential value DOX is less than "0", the process proceeds to step 110 to determine whether the previous differential value DOX is less than "0". If it is determined in step 110 that the difference is less than “0”, that is, if it is determined that the differential value of the output voltage of the O 2 sensor 15 is still negative, the processing from step 104 is performed.
If it is determined in step 110 that the value is equal to or greater than “0”, that is, if it is determined that the differential value of the output voltage of the O 2 sensor 15 has been inverted from positive to negative, the process proceeds to step 111 and the previous air-fuel ratio correction coefficient The current air-fuel ratio correction coefficient FAF is calculated by adding a predetermined skip K (positive value) to the FAF, and stored in the RAM 22c as the previous air-fuel ratio correction coefficient FAF used in the next routine.
そして、ECU21は上記の空燃比補正係数算出処理を実
行して算出した空燃比補正係数FAFに基いて、燃料噴射
弁２から噴射される燃料噴射量を公知の燃料噴射量算出
処理において修正する。そして、このように修正された
燃料量がエンジン１に供給されることで、混合気は目標
空燃比近傍に調整される。Then, the ECU 21 corrects the fuel injection amount injected from the fuel injection valve 2 in a known fuel injection amount calculation process based on the air-fuel ratio correction coefficient FAF calculated by executing the above-described air-fuel ratio correction coefficient calculation process. Then, by supplying the fuel amount corrected in this way to the engine 1, the air-fuel mixture is adjusted to be near the target air-fuel ratio.
このように、本実施例の空燃比制御装置では、目標空
燃比と実際の空燃比との偏差に基いて空燃比補正係数FA
Fをフィードバック処理して設定するとともに、第７図
に示すようにO2センサ15の出力電圧の微分値（変化分）
が負から正に反転変化したとき、前回の空燃比補正係数
FAFから所定のスキップＫを減算して今回の空燃比補正
係数FAFを求め、又、出力電圧の微分値が正から負に反
転変化したとき、前回の空燃比補正係数FAFに所定のス
キップＫを加算して今回の空燃比補正係数FAFを求める
ようにしている、即ち、O2センサ出力電圧OXの微分値
（変化分）が正から負、又は負から正に反転変化したと
きに空燃比補正係数FAFを実空燃比が目標空燃比（理論
空燃比）に近づく側に所定のスキップＫだけフィードフ
ォワード処理により変化させるので、燃料噴射弁２が燃
料を噴射してから燃焼してO2センサ15にて酸素濃度が検
出されるまでのガス遅れ時間を充分に補償することがで
きる。なお、第８図に示すタイムチャートは単に目標空
燃比と実空燃比との偏差に基いてフィードバック処理し
て設定される空燃比補正係数FAFにより空燃比制御した
ものを示すものであり、この第８図のものと比較して、
本実施例構成の装置では空燃比補正制御の応答性を高
め、エミッションを向上することができる。特に、加速
時において実際の空燃比に対する空燃比補正係数の追い
掛けが速くなり、エミッション悪化域を狭くすることが
できる。As described above, in the air-fuel ratio control device of the present embodiment, the air-fuel ratio correction coefficient FA is determined based on the deviation between the target air-fuel ratio and the actual air-fuel ratio.
F is set by feedback processing, and the differential value (change) of the output voltage of the O 2 sensor 15 as shown in FIG.
Is changed from negative to positive, the previous air-fuel ratio correction coefficient
A predetermined skip K is subtracted from the FAF to obtain the current air-fuel ratio correction coefficient FAF.When the output voltage differential value changes from positive to negative, the predetermined skip K is added to the previous air-fuel ratio correction coefficient FAF. The air-fuel ratio correction coefficient FAF is obtained by adding the values, that is, the air-fuel ratio correction is performed when the differential value (change) of the O 2 sensor output voltage OX changes from positive to negative or from negative to positive. since the coefficient FAF is the actual air-fuel ratio is changed by only feedforward processing predetermined skip K approaches the side in the target air-fuel ratio (stoichiometric air-fuel ratio), O 2 sensor 15 fuel injection valve 2 is burned after injecting fuel Thus, the gas delay time until the oxygen concentration is detected can be sufficiently compensated. It should be noted that the time chart shown in FIG. 8 merely shows the air-fuel ratio controlled by the air-fuel ratio correction coefficient FAF set by performing feedback processing based on the deviation between the target air-fuel ratio and the actual air-fuel ratio. Compared to the one in Fig. 8,
In the device of this embodiment, the response of the air-fuel ratio correction control can be increased, and the emission can be improved. In particular, during acceleration, the tracking of the air-fuel ratio correction coefficient with respect to the actual air-fuel ratio becomes faster, and the emission deterioration range can be narrowed.
なお、前記実施例ではO2センサ15の出力電圧の微分値
が負から正、又は正から負に変化したときのスキップＫ
を等しくしていたが、空燃比がリッチからリーンに変化
する場合に反応時間が長くなるO2センサ15の特性を考慮
して、出力電圧の微分値が正から負に変化したときのス
キップを微分値が負から正に変化したときのスキップよ
りも大きく設定してもよい。In the above embodiment, the skip K when the differential value of the output voltage of the O 2 sensor 15 changes from negative to positive or from positive to negative.
Although was equal, in consideration of the characteristics of the O 2 sensor 15 which air-fuel ratio becomes long reaction times vary from rich to lean, the skip when the differential value of the output voltage changes from positive to negative The value may be set to be larger than the skip when the differential value changes from negative to positive.
又、前記実施例ではエンジン回転数、吸気管内圧力等
によるエンジン運転状態に関係なく、スキップＫを一定
値としていたが、運転状態によって燃料噴射弁２から供
給された燃料が混合気としてエンジン燃焼室内に導か
れ、O2センサ15に排ガスとして到達するまでの時間には
違いがあるので、例えば、高回転領域ではガス遅れ時間
が小さいのでスキップＫを小さくする、とういように運
転状態によってスキップＫを変化させるようにしてもよ
い。In the above-described embodiment, the skip K is set to a constant value irrespective of the engine operating state due to the engine speed, the pressure in the intake pipe, etc. However, depending on the operating state, the fuel supplied from the fuel injection valve 2 is converted into a fuel-air mixture in the engine combustion chamber. There is a difference in the time required for the gas to reach the O 2 sensor 15 as exhaust gas. For example, in the high rotation region, the gas delay time is small, so the skip K is reduced. May be changed.
又、前記実施例ではO2センサ15の出力電圧の微分値が
負から正、又は正から負に反転変化する毎に空燃比補正
係数FAFに所定のスキップＫを加算又は減算していた
が、例えば前回回転数センサ18からのパルス、又はスロ
ットルポジションセンサ13の開度センサ13aの信号変化
や、アイドルスイッチ13bの信号変化に基いて加速状態
を検出する加速検出手段を設け、この加速検出手段によ
り加速状態が検出され、O2センサ15の出力電圧の微分値
が正から負に変化したときにのみ、空燃比補正係数FAF
に所定のスキップを加算するようにしてもよい。Further, in the above-described embodiment, the predetermined skip K is added or subtracted to the air-fuel ratio correction coefficient FAF each time the differential value of the output voltage of the O 2 sensor 15 changes from negative to positive or from reverse to positive to negative. For example, acceleration detection means for detecting an acceleration state based on a pulse from the previous rotation speed sensor 18 or a signal change of the opening degree sensor 13a of the throttle position sensor 13 or a signal change of the idle switch 13b is provided. accelerating state is detected, when the differential value of the output voltage of the O 2 sensor 15 changes from positive to negative only, the air-fuel ratio correction coefficient FAF
May be added to the predetermined skip.
さらに、前記実施例では燃料噴射弁２を備えたエンジ
ンに具体化したが、キャブレターを備えたエンジンに具
体化してもよい。Further, in the above embodiment, the present invention is embodied in an engine having the fuel injection valve 2, but may be embodied in an engine having a carburetor.
［発明の効果］ 以上詳述したように、本発明による空燃比制御装置に
よれば、燃料が供給されてから燃焼して酸素濃度センサ
にて酸素濃度が検出されるまでのガス遅れ時間を充分に
補償でき、空燃比補正制御の応答性を高めてエミッショ
ンを向上することができる優れた効果がある。[Effects of the Invention] As described above in detail, according to the air-fuel ratio control apparatus of the present invention, the gas delay time from the supply of fuel to the combustion and the detection of the oxygen concentration by the oxygen concentration sensor is sufficient. And the emission efficiency can be improved by improving the responsiveness of the air-fuel ratio correction control.
第１図は本発明のクレーム対応図、第２図は本発明を具
体化した一実施例による空燃比制御装置を搭載したエン
ジン及びその周辺装置を示す構成図、第３図は電気的構
成を示すブロック図、第４図は電子制御回路が実行する
処理を示すフローチャート、第５図（ａ）は酸素濃度セ
ンサ出力と空燃比との関係を示すグラフ、第５図（ｂ）
は第５図（ａ）の酸素濃度センサ出力と空燃比との関係
を反転したマップ、第６図（ａ）は空燃比偏差にて規定
した比例値マップ、第６図（ｂ）は空燃比偏差にて規定
した積分値マップ、第７図及び第８図はO2センサ信号に
対する空燃比補正係数の変化を示すタイムチャートであ
る。 図中、１は内燃機関としてのエンジン、２は燃料噴射
弁、４は吸気系、９は排気系、12は吸気圧センサ、15は
酸素濃度センサ、15aは検出素子、15bはヒータ、18は回
転数センサ、21は空燃比偏差検出手段，反転検出手段，
空燃比制御量設定手段及び空燃比制御手段としての電子
制御回路である。FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a configuration diagram showing an engine equipped with an air-fuel ratio control device according to an embodiment of the present invention, and peripheral devices thereof, and FIG. FIG. 4 is a flowchart showing the processing executed by the electronic control circuit. FIG. 5 (a) is a graph showing the relationship between the oxygen concentration sensor output and the air-fuel ratio, and FIG. 5 (b).
6A is a map obtained by inverting the relationship between the oxygen concentration sensor output and the air-fuel ratio in FIG. 5A, FIG. 6A is a proportional value map defined by the air-fuel ratio deviation, and FIG. FIGS. 7 and 8 are time charts showing changes in the air-fuel ratio correction coefficient with respect to the O 2 sensor signal. In the figure, 1 is an engine as an internal combustion engine, 2 is a fuel injection valve, 4 is an intake system, 9 is an exhaust system, 12 is an intake pressure sensor, 15 is an oxygen concentration sensor, 15a is a detection element, 15b is a heater, 18 is A rotational speed sensor, 21 is an air-fuel ratio deviation detecting means, a reversing detecting means,
It is an electronic control circuit as an air-fuel ratio control amount setting unit and an air-fuel ratio control unit.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭52−135923（ＪＰ，Ａ) 特開 昭61−112758（ＪＰ，Ａ) 特開 昭64−73146（ＪＰ，Ａ) 特開 平１−125542（ＪＰ，Ａ) 特開 平１−147135（ＪＰ，Ａ) 特開 平１−313641（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-52-135923 (JP, A) JP-A-61-112758 (JP, A) JP-A-64-73146 (JP, A) JP-A-1- 125542 (JP, A) JP-A-1-147135 (JP, A) JP-A-1-313641 (JP, A)
Claims (2)
機関の排ガス中の酸素濃度を検出して機関に供給された
混合気の実空燃比に応じた信号を出力する酸素濃度セン
サと、 前記酸素濃度センサの出力信号に基づいて、所望の目標
空燃比と前記実空燃比との空燃比偏差を検出する空燃比
偏差検出手段と、 前記酸素濃度センサの実空燃比に応じた出力信号の変化
分が正から負、又は負から正に反転変化したことを検出
する反転検出手段と、 前記空燃比偏差検出手段にて検出された前記空燃比偏差
に対応して空燃比制御量を設定するとともに、前記反転
検出手段にて前記反転変化が検出されたとき、前記空燃
比制御量を前記実空燃比が前記目標空燃比に近づく側に
所定量変化させる空燃比制御量設定手段と、 前記空燃比制御量設定手段にて設定された前記空燃比制
御量に基づいて機関に供給される混合気の空燃比を制御
する空燃比制御手段とを備えたことを特徴とする内燃機
関の空燃比制御装置。An oxygen concentration sensor is provided in an exhaust system of an internal combustion engine, and detects an oxygen concentration in exhaust gas of the internal combustion engine and outputs a signal corresponding to an actual air-fuel ratio of an air-fuel mixture supplied to the engine. Air-fuel ratio deviation detecting means for detecting an air-fuel ratio deviation between a desired target air-fuel ratio and the actual air-fuel ratio based on an output signal of the oxygen concentration sensor; and an output signal corresponding to the actual air-fuel ratio of the oxygen concentration sensor Reversal detecting means for detecting that the change amount of the reversal changes from positive to negative, or from negative to positive, and setting the air-fuel ratio control amount corresponding to the air-fuel ratio deviation detected by the air-fuel ratio deviation detecting means. And an air-fuel ratio control amount setting unit configured to change the air-fuel ratio control amount by a predetermined amount toward the side where the actual air-fuel ratio approaches the target air-fuel ratio when the inversion change is detected by the inversion detection unit. Set by the air-fuel ratio control amount setting means An air-fuel ratio control device for controlling an air-fuel ratio of an air-fuel mixture supplied to the engine based on the air-fuel ratio control amount obtained.
比に対する酸素濃度センサの出力特性に基づいて、目標
空燃比と該混合気の空燃比との空燃比偏差と、酸素濃度
センサの出力信号との関係を予め記憶しておく記憶手段
と、前記記憶手段に記憶しておいた前記関係を用いて、
前記酸素濃度センサの出力信号に対応して前記空燃比偏
差を読み出す空燃比偏差読出手段とを含むことを特徴と
する請求項１記載の内燃機関の空燃比制御装置。2. An air-fuel ratio deviation detecting means, comprising: an air-fuel ratio deviation between a target air-fuel ratio and an air-fuel ratio of the air-fuel mixture; Using storage means for storing the relationship with the output signal in advance, and the relationship stored in the storage means,
2. The air-fuel ratio control device for an internal combustion engine according to claim 1, further comprising: air-fuel ratio deviation reading means for reading the air-fuel ratio deviation in response to the output signal of the oxygen concentration sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17736588A JP2600824B2 (en) | 1988-07-15 | 1988-07-15 | Air-fuel ratio control device for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17736588A JP2600824B2 (en) | 1988-07-15 | 1988-07-15 | Air-fuel ratio control device for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0227137A JPH0227137A (en) | 1990-01-29 |
| JP2600824B2 true JP2600824B2 (en) | 1997-04-16 |
Family
ID=16029684
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17736588A Expired - Fee Related JP2600824B2 (en) | 1988-07-15 | 1988-07-15 | Air-fuel ratio control device for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2600824B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02153242A (en) * | 1988-12-02 | 1990-06-12 | Nissan Motor Co Ltd | Air-fuel ratio control device for internal combustion engine |
| JP4995487B2 (en) * | 2006-05-24 | 2012-08-08 | 日本特殊陶業株式会社 | Gas sensor deterioration signal generator |
-
1988
- 1988-07-15 JP JP17736588A patent/JP2600824B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0227137A (en) | 1990-01-29 |
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