JPS60187749A - Air-fuel ratio controlling apparatus for engine having carburetor - Google Patents

Air-fuel ratio controlling apparatus for engine having carburetor

Info

Publication number
JPS60187749A
JPS60187749A JP4259884A JP4259884A JPS60187749A JP S60187749 A JPS60187749 A JP S60187749A JP 4259884 A JP4259884 A JP 4259884A JP 4259884 A JP4259884 A JP 4259884A JP S60187749 A JPS60187749 A JP S60187749A
Authority
JP
Japan
Prior art keywords
air
fuel ratio
throttle valve
control
engine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP4259884A
Other languages
Japanese (ja)
Inventor
Hiroyuki Nomura
博之 野村
Itsuo Komatsu
小松　逸夫
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 JP4259884A priority Critical patent/JPS60187749A/en
Publication of JPS60187749A publication Critical patent/JPS60187749A/en
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M11/00—Multi-stage carburettors, Register-type carburettors, i.e. with slidable or rotatable throttling valves in which a plurality of fuel nozzles, other than only an idling nozzle and a main one, are sequentially exposed to air stream by throttling valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M3/00—Idling devices for carburettors
    • F02M3/08—Other details of idling devices
    • F02M3/09—Valves responsive to engine conditions, e.g. manifold vacuum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M7/00—Carburettors with means for influencing, e.g. enriching or keeping constant, fuel/air ratio of charge under varying conditions
    • F02M7/23—Fuel aerating devices
    • F02M7/24—Controlling flow of aerating air

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of The Air-Fuel Ratio Of Carburetors (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

PURPOSE:To enable to purify the exhaust gas and to increase the output of an engine over the entire operational range of the engine, by lowering the air-fuel ratio by stopping feedback control of a carburetor when a secondary throttle valve that is opened only at the time of high-load operation of the engine is operated. CONSTITUTION:When a primary throttle valve 14 of a carburetor 10 is fully opened, a secondary throttle valve 18 is opened by operating an actuator 30A by the negative pressure acted at a port 24 of a venturi 20. That the secondary throttle valve 18 is opened is detected by an opening detecting switch 36, and the output signal is applied to a control unit 42. The control unit 42 executes ordinary feedback control of a main air bleed 38, a slow air bleed 40 and a control solenoid valve 34 until the output signal of said switch 36 is applied to the control unit 42. However, when the output signal of the switch 36 is applied to the unit 42, it stops feedback control and lowers the air-fuel ratio.

Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は、気化器エンジンの空燃比制御装置に係り、特
に、排気ガス浄化対策が施された自動車用エンジンに用
いるのに好適な、常時作動する一次側絞り弁と、高負荷
時にのみ開かれる二次側絞り弁とを有する気化器エンジ
ンの空燃比制御装置の改良に関する。The present invention relates to an air-fuel ratio control device for a carburetor engine, and is particularly suitable for use in an automobile engine equipped with exhaust gas purification measures. The present invention relates to an improvement in an air-fuel ratio control device for a carburetor engine having a secondary throttle valve.

【従来技術】[Prior art]

自動車用エンジンとして、常時作動する一次側絞り弁と
、高負荷時にのみ開かれる二次側絞り弁とを有する２連
式気化器を備えた気化器エンジンが広く用いられている
。この気化器エンジンにおいて、排気ガス浄化性能等を
向上するｌ＼く、空燃比を精密に制御する際には、排気
ガスの空燃比を検出するための空燃比センサと、エンジ
ン燃焼至に吸入される混合気の空燃比を、例えばエアブ
リード量又は燃料流量を制御することによって制御する
ための空燃比制御アクチュエータとを設け、前記空燃比
センサの出力に応じて、空燃比が設定値となるよう、前
記空燃比副部アクチュエータをフィードバック制御する
ようにしたものがある。 このような空燃比フィードバック制御を採用した場合に
は、空燃比を常時設定値に維持することができ、従って
、高い排気ガス浄化性能を得ることができるものである
が、一方、登板等の高負荷時や、高速走行時あるいは急
加速時等のように大出力を必要とする場合にも、空燃比
が一定となるように制御してしまうため、力不足となり
、加速性能等が悪化してしまうという問題点を有してい
１こ　。 このような問題点を解消するべく、吸気管負圧が設定値
以下となったことを検出するための負圧スイッチを設け
て、該負圧スイッチが作動した時は、前記フィードバッ
ク制御を停止することが行われているが、高負荷を多用
する車両では、しばしば空燃比のフィードバック制御が
停止されるため、排気ガス浄化性能上不利となり、空燃
比制御装置に停止遅延装置を追加する必要がある。しか
しながら、このような停止遅延装置を追加した場合には
、力の必要となる高負荷時（叩ち、二次側絞り弁使用域
）でも空燃比フィードバック制御が行われてしまい、力
不足となることがあるという問題点を有していた。 即ち、この従来例における負圧スイッチによる空燃比制
御停止線は、第１図に破線Ａで示す如くであり、この負
圧スイッチによるフィードバック制御停止域（破線Ａの
上方）においても、排気ガス浄化性能上、空燃比フィー
ドバック制御が必要な領域（斜線Ｂ）が存在Ｊる。この
ため、空燃比フィードバック制御停止時に遅延時間を追
加する必要があるものであるが、このようにすると、遅
延時間中は全域で空燃比フィードバック制御が行われる
こととなり、右下り斜線Ｃで示ず、出力性能上空燃比フ
ィードバック制御が不要な領域で出力低下が発生してし
まう。 又、例えば、特開昭５１−１０２７２６に示される如く
、高出力時や急加速時等を一次側絞り弁の全開状態で検
出し、−次側絞り弁の全開時には、空燃比制御装置内の
積分回路の出力を一定に保持するか、あるいはアクチュ
エータ駆動回路の出力を変化させて、空燃比制御アクチ
ュエータを空燃比が小さくなる位置で停止させるかの少
なくとも一方の方法を行なうことによって、空燃比を平
常時より小さくするようにして、出力性能を向上させる
ようにすることも提案されているが、この空燃比制御装
置においても、−次側絞り弁が全開にならないとフィー
ドバック制御が停止されないので、加速開始時に十分な
加速性能が得られないという問題点を有していた。 一方、二次側絞り弁使用域における加速性能を向上させ
るべく、なるべく速い時期、例えば−次側絞り弁の全開
状態より前の高開度領域で空燃比フィードバック制御を
停止することも考えられるが、このようにした場合には
、通常の運転で使用される一次側絞り弁使用域で空燃比
フィードバック制御が停止されることとなり、排気ガス
浄化性能上好ましくないという問題点を有していた。2. Description of the Related Art As an automobile engine, a carburetor engine equipped with a dual carburetor having a primary throttle valve that is always operated and a secondary throttle valve that is opened only when the load is high is widely used. In this carburetor engine, in order to improve exhaust gas purification performance, etc., when precisely controlling the air-fuel ratio, an air-fuel ratio sensor is used to detect the air-fuel ratio of exhaust gas, and an air-fuel ratio sensor is used to detect the air-fuel ratio of exhaust gas. an air-fuel ratio control actuator for controlling the air-fuel ratio of the air-fuel mixture by, for example, controlling an air bleed amount or a fuel flow rate, and the air-fuel ratio is set to a set value according to the output of the air-fuel ratio sensor. , there is one in which the air-fuel ratio sub-section actuator is feedback-controlled. When such air-fuel ratio feedback control is adopted, the air-fuel ratio can be maintained at the set value at all times, and therefore high exhaust gas purification performance can be obtained. Even when high output is required, such as under load, when driving at high speeds, or when accelerating suddenly, the air-fuel ratio is controlled to be constant, resulting in insufficient power and poor acceleration performance. One problem is that it can be stored away. In order to solve this problem, a negative pressure switch is provided to detect when the intake pipe negative pressure is below a set value, and when the negative pressure switch is activated, the feedback control is stopped. However, in vehicles that frequently use high loads, feedback control of the air-fuel ratio is often stopped, which is disadvantageous in terms of exhaust gas purification performance, and it is necessary to add a stop delay device to the air-fuel ratio control device. . However, if such a stop delay device is added, air-fuel ratio feedback control will be performed even under high loads that require force (striking, secondary throttle valve usage range), resulting in insufficient power. However, there were some problems. That is, the air-fuel ratio control stop line by the negative pressure switch in this conventional example is as shown by the broken line A in FIG. In terms of performance, there is a region (diagonal line B) where air-fuel ratio feedback control is necessary. For this reason, it is necessary to add a delay time when the air-fuel ratio feedback control is stopped, but if this is done, the air-fuel ratio feedback control will be performed throughout the entire area during the delay time, which is not shown by the downward diagonal line C. , a decrease in output occurs in a region where air-fuel ratio feedback control is unnecessary in terms of output performance. For example, as shown in Japanese Patent Application Laid-Open No. 51-102726, high output or sudden acceleration can be detected when the primary throttle valve is fully open, and when the primary throttle valve is fully open, the air-fuel ratio control device is activated. The air-fuel ratio can be adjusted by holding the output of the integrating circuit constant or by changing the output of the actuator drive circuit and stopping the air-fuel ratio control actuator at a position where the air-fuel ratio becomes smaller. It has also been proposed to improve output performance by making it smaller than normal, but even in this air-fuel ratio control device, feedback control will not be stopped unless the downstream throttle valve is fully open. There was a problem in that sufficient acceleration performance could not be obtained at the start of acceleration. On the other hand, in order to improve acceleration performance in the region where the secondary throttle valve is used, it may be possible to stop the air-fuel ratio feedback control as early as possible, for example in the high opening region before the downstream throttle valve is fully open. In this case, the air-fuel ratio feedback control is stopped in the primary side throttle valve usage range used in normal operation, which is unfavorable in terms of exhaust gas purification performance.

【発明の目的】[Purpose of the invention]

本発明は、前記従来の問題点を解消するべくなされたも
ので、排気ガス浄化性能を損うことなく、加速性能を向
上することができる気化器エンジンの空燃比制御装置を
提供することを目的とする。The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an air-fuel ratio control device for a carburetor engine that can improve acceleration performance without impairing exhaust gas purification performance. shall be.

【発明の構成】[Structure of the invention]

本発明は、常時作動する一次側絞り弁と、高負荷時にの
み開かれる二次側絞り弁とを有する気化器エンジンの空
燃比制御装置において、排気ガスの空燃比を検出するた
めの空燃比センサと、エンジン燃焼室に吸入される混合
気の空燃比を制御するための空燃比制御アクチュエータ
と、二次側絞り弁の開度又は二次側絞り弁制御アクチュ
エータの制御負圧が設定値以上となったことを検出する
ための開度又は制御負圧検出スイッチと、通常時は、前
記空燃比センサの出力に応じて、空燃比が設定値となる
よう、前記空燃比制御アクチュエータをフィードバック
制御し、一方、前記開度又は制御負圧検出スイッチが作
動した時は、前記フィードバック制御を停止して、空燃
比が通常時より小となるよう、前記空燃比制御アクチュ
エータを制御する空燃比制御回路と、を備えることによ
り、前記目的を達成したものである。The present invention provides an air-fuel ratio sensor for detecting the air-fuel ratio of exhaust gas in an air-fuel ratio control device for a carburetor engine that has a primary throttle valve that operates constantly and a secondary throttle valve that opens only during high loads. and an air-fuel ratio control actuator for controlling the air-fuel ratio of the air-fuel mixture taken into the engine combustion chamber, and the opening degree of the secondary throttle valve or the control negative pressure of the secondary throttle valve control actuator is equal to or higher than a set value. an opening or control negative pressure detection switch for detecting whether the air-fuel ratio has changed, and feedback control of the air-fuel ratio control actuator so that the air-fuel ratio is at a set value according to the output of the air-fuel ratio sensor during normal times. , on the other hand, an air-fuel ratio control circuit that controls the air-fuel ratio control actuator so that when the opening degree or control negative pressure detection switch is activated, the feedback control is stopped and the air-fuel ratio is smaller than normal; The above object has been achieved by providing the following.

【発明の作用】[Action of the invention]

本発明（よ、排気ガス浄化性能上必要な低速側では、殆
んど一次側絞り弁のみが使用されており、一方、出力性
能の必要な二次側絞り弁の使用域は、使用頻度が少ない
ので排気ガス浄化性能上は殆んど問題とならないことに
着目してなされたもので、二次側絞り弁の開度又は二次
側絞り弁制御アクチュエータの制御負圧が設定置以上と
なった時に、空燃比フィードバック制御を停止して、空
燃比が通常時より小となるよう、空燃比制御アクチュエ
ータを制御１″ｇるようにしたので、排気ガス浄化対策
上必要な低速高負荷の空燃比フィー１〜バツク制御域が
増大されて、排気ガス浄化性能か向上覆る。 しかも、中高迭筒負荷の空燃比フィードバック制御の停
止に際しては、遅延時間が不要となるため、加速開始時
の出力性能従って加速性能を向上することができる。 本発明における、空燃比フィードバック制御停止線を前
出第１図に実線りで示す。 【実施例］ 以下図面を参照して、本発明の実施例を詳細に説明する
。 本実施例は、第２図及び第３図に示す如く、２浬式気化
器１０の１次側吸気通路１２に配設された、アクセルペ
ダル（ｍｌ示省略）と連動して常時作動する１次側絞り
弁１４と、前記２連式気化器１０の２次側吸気通路１６
に配設された、高負荷時にのみ開かれる２次側絞り弁１
８と、１次側ラージベンチュリ２０及び２次側ラージベ
ンチュリ２２の負圧が絞り２４．２６．２８を介して導
入されるダイヤフラム’Ｊ３０Ａを有し、該ダイヤフラ
ムｘＳｏＡ内に導入される負圧によって、高負荷時にの
み前記２次側絞り弁１８を聞くための２次側絞り弁制御
アクチュエータ３０とを有する気化器エンジンの空燃比
制御装置において、排気ガスの空燃比を検出するための
空燃比センサ３２と、エンジン燃焼至に吸入される混合
気の空燃比を、２連式気化器１０のメインエアブリード
量及びスローエアブリード量を制御することによって制
御するための空燃比制御弁３４と、前記２次側絞り弁１
８が開かれ始めたことを検出するための開度検出スイッ
チ３６と、通常時は、前記空炉１比センサ３２の出力に
応じて、空燃比が設定値、例えば理論空燃比となるよう
、前記空燃比制御弁３８を、例えばオンオフチューティ
制御によりフィードバック制御して、メインエアブリー
ド通路３８及びスローエ）７ブリ一ド通路４０に導入さ
れる大気昆を調整し、一方、前記開度検出スイッチ３６
が作動した時は、前記フィードバック制御を停止して、
空燃比が通常時より小となるよう、前記空燃比制御弁３
４からのメインエアブリード通路３８及びスローエアブ
リード通路４０に対づる大気の導入が停止されるよう、
前記空燃比制御ル弁３４を制御づる空燃比制御回路４２
と、をＬ＠えたものである。 第２図において、５０は吸気管、５２はエンジン本体、
５４は排気管、５６は触媒コンバータである。 又、第３図において、６０はフロート至、６２はメイン
ジェット、６４はメインウェル、６６はメインエアブリ
ード管、６８は１次側メインウェル、７０はスローエア
ブリード管、７２はスローボート、７′４はアイドルボ
ー１〜．７６はアイドル調整ねじである。 前記空燃化制御回路４２は、例えば第４図に詳細に示す
如く、電源電圧ＶＣＣを分圧して基準電圧Ｖｏを発生づ
るための分圧抵抗Ｒ＋、Ｒ２と、十入力端子に与えられ
る前記基準電圧Ｖｏと入力端子８０を介して一入力端子
に与えられる前記空燃比センサ３２出力の偏差信号を出
力する作動増幅器８２と、該作動増幅器８２出力の偏差
信号の変化に比例した比例信号を出力する比例回路８４
と、前記偏差信号を積分した積分信号を出力する積分回
路８６と、オンオフデユーティ制御を行うためのディザ
１３号を発生づるディザ発振器８８と、前記比例回路８
４出力の比例信号、前記積分回路８６出力の積分信号及
び前記ディザ発振器８８出力のディザ伝号に応じて、比
例信号と積分信号の和に対応したパルス幅を持つパルス
信号を出力する比較器９０と、該比較器９０の出力に応
じて、前記字燃比制御弁３４を駆動するためのスイッチ
ングトランジスタＱ１及びＱ２を含む駆動回路９２とか
ら構成されている。この空燃比制御回路４２において、
前記開度検出スイッチ３６の出力は、前記駆動回路９２
のスイッチングトランジスタＱ１の人力信号を接地する
スイッチＳ１に与えられている。従って、スイッチＳ＋
かオンとなると、スイッチングトランジスタＱ　＋　、
Ｑ　２は、パルス信号と無関係に常にオフとなり、空燃
比制御弁３４は常に復帰状態に保持されるので、エアブ
リード量が減少して、混合気は通常時より過濃な状態に
維持される。 以下作用を説明する。 まず１次側絞り弁１４のみが作動しており、２次側絞り
弁１８が２次側絞り弁制御アクチュエ〜り３０によって
間かれることがない通常時には、前記開度検出スイッチ
３６は、作動することがない。従って、この通常時には
、常詩空燃比フィードバック制御が行われることとなり
、排気ガス浄化対策上必要な低速高負荷域の空燃比フィ
ードバック制御域が増大されて、排気ガス浄化性能が向
上する。 一方、前記２次側絞り弁制御アクチュエータ３０によっ
て２次側絞り弁１８が開かれ始めると、直らに前記開度
検出スイッチ３６が作動して、その接点３６Ａが開かれ
る。すると、前記スイッチＳ１がオンとされるため、前
記空燃比制御弁３４の作動が停止され、これによって、
空燃比制御弁３４からのメインエアブリード通路３８及
びスローエアブリード通路４０に対する大気導入が停止
されて、空燃比が小さくなり、出力空燃比となって、出
力性能が向上され、加速性能が向上される。 本実施例における、全開加速時の経過時間とトルクの関
係の例を第５図に実線りで示す。同じく破線Ａで示した
従来例に比べて、全開加速時のトルクの立上りが速く、
従って、加速性能が向上されていることが明らかである
。 本実施例においては、２次側絞り弁１８の開度が設定値
以上となった時に、空燃比のフィードバック制御を停止
するようにしているので、２次側絞り弁１８が作動を開
始する瞬間を確実に検出することができる。なお、２次
側絞り弁１８の作動状態を検出Ｊる方法はこれに限定さ
れず、例えば、前出第３図に破線で示したように、前記
２次側絞り弁制御アクチュエータ３０のダイアフラム室
３０Ａに供給される制御負圧が設定値以上となったこと
を検出づるための制御負圧検出スイッチ１００を設け、
該負圧検出スイッチ１００の出力に応じて、前記駆動回
路９２のスイッチＳ１を開閉づることも可能である。こ
の場合には、ダイアフラム室３０Ａに導入される制御負
圧が高まり始めた時点で空燃比のフィードバック制御を
停止することができ、従って、実際に２次側絞り弁１８
が開かれる直前にフィードバック制御を停止して、加速
性能を一層向上づることができる。 又、前記実施例においては、駆動回路９２のスイッチン
グトランジスタＱ１の入力信号をスイッチＳ１によって
接地することにより、空燃比フィードバック制御を停止
させるようにしていたが、開度検出スイッチ３６又は制
御負圧検出スイッチ１００が作動した時に空燃比フィー
ドバック制御を停止する方法はこれに限定されず、例え
ば、前記積分口７路８６の帰還回路を短絡するスイッチ
Ｓ２を設けて、これによりフィードバック制御を停止づ
ることも可能である。即ち、この場合には、スイッチＳ
２が・オンになると、積分回路８６の積分値定数を決定
するコンデンサＣ１が短絡され、積分回路８６の出力が
一定値になる。従って、空燃比センサ３２の出力が基準
電圧Ｖｏより高い状態（混合気過濃）が継続しても、パ
ルス信号のパルス幅は一定値（比例分による分）以上に
は増加せず、そのため混合気は平常時より過濃な状態に
維持されるものである。 更に、・前記実施例においては、空燃比制御アクチユエ
ータとして、エアブリード儲を制ｔｉｔ＋ｉる空燃比制
御弁３４が用いられていたが、空燃比制御アクチュエー
タの種類は、これに限定されず、例えば、燃料流量を制
御するものを用いることも可能である。 ［発明の効果］ 以上説明した通り、本発明によれば、排気ガス浄化対策
上必要な低速高負荷の空燃比フィードバック制御Ｉ域が
増大され、排気ガス浄化性能が向上する。又、中高速高
負荷の空燃比フィードバック停止に際しては、遅延時間
を用いる必要がないため、迅速なフィードバック制御停
止が可能となり、加速開始時の出力性能従って加速性能
を大幅に向上することが可能となるという優れた効果を
有する。According to the present invention, almost only the primary throttle valve is used on the low speed side, which is necessary for exhaust gas purification performance, while the secondary throttle valve, which requires output performance, is used less frequently. This was done with the focus on the fact that it poses almost no problem in terms of exhaust gas purification performance because the amount is so small that the opening of the secondary throttle valve or the controlled negative pressure of the secondary throttle valve control actuator exceeds the set point. When this happens, the air-fuel ratio feedback control is stopped and the air-fuel ratio control actuator is controlled by 1"g so that the air-fuel ratio is lower than normal. The fuel ratio fee 1 to back control range is increased, which improves exhaust gas purification performance.Moreover, when stopping air-fuel ratio feedback control for medium and high cylinder loads, no delay time is required, so the output performance at the start of acceleration is improved. Therefore, acceleration performance can be improved. The air-fuel ratio feedback control stop line in the present invention is shown as a solid line in FIG. As shown in FIGS. 2 and 3, this embodiment operates in conjunction with an accelerator pedal (ml not shown) disposed in the primary intake passage 12 of the two-stroke carburetor 10. A primary throttle valve 14 that is always operated and a secondary intake passage 16 of the dual carburetor 10.
Secondary throttle valve 1, which opens only under high load, is installed in
8 and a diaphragm 'J30A through which the negative pressure of the primary large venturi 20 and the secondary large venturi 22 is introduced through the restrictor 24, 26, 28, and the negative pressure introduced into the diaphragm xSoA , and a secondary throttle valve control actuator 30 for listening to the secondary throttle valve 18 only during high loads. 32, an air-fuel ratio control valve 34 for controlling the air-fuel ratio of the air-fuel mixture taken into the engine for combustion by controlling the main air bleed amount and slow air bleed amount of the dual carburetor 10; Secondary throttle valve 1
an opening detection switch 36 for detecting that the air furnace 8 has begun to open; The air-fuel ratio control valve 38 is feedback-controlled by, for example, on-off control to adjust the atmospheric air introduced into the main air bleed passage 38 and the slow air bleed passage 40, while the opening detection switch 36
When activated, stop the feedback control and
The air-fuel ratio control valve 3 is configured so that the air-fuel ratio is smaller than normal.
4 to the main air bleed passage 38 and the slow air bleed passage 40 are stopped.
an air-fuel ratio control circuit 42 that controls the air-fuel ratio control valve 34;
, which is obtained by L@. In FIG. 2, 50 is an intake pipe, 52 is an engine body,
54 is an exhaust pipe, and 56 is a catalytic converter. In FIG. 3, 60 is the float, 62 is the main jet, 64 is the main well, 66 is the main air bleed pipe, 68 is the primary side main well, 70 is the slow air bleed pipe, 72 is the slow boat, and 7' 4 is Idol Bo 1~. 76 is an idle adjustment screw. As shown in detail in FIG. 4, for example, the air/fuel conversion control circuit 42 includes voltage dividing resistors R+ and R2 for dividing the power supply voltage VCC to generate a reference voltage Vo, and the reference voltage applied to the ten input terminals. A differential amplifier 82 outputs a deviation signal of the output of the air-fuel ratio sensor 32 which is applied to one input terminal via the voltage Vo and an input terminal 80, and outputs a proportional signal proportional to a change in the deviation signal of the output of the differential amplifier 82. Proportional circuit 84
, an integration circuit 86 that outputs an integral signal obtained by integrating the deviation signal, a dither oscillator 88 that generates dither No. 13 for performing on/off duty control, and the proportional circuit 8
a comparator 90 that outputs a pulse signal having a pulse width corresponding to the sum of the proportional signal and the integral signal in accordance with the proportional signal of the four outputs, the integral signal of the output of the integrating circuit 86, and the dither signal of the output of the dither oscillator 88; and a drive circuit 92 including switching transistors Q1 and Q2 for driving the linear fuel ratio control valve 34 according to the output of the comparator 90. In this air-fuel ratio control circuit 42,
The output of the opening detection switch 36 is transmitted to the drive circuit 92.
A switch S1 is provided to ground the human input signal of the switching transistor Q1. Therefore, switch S+
When the switch is turned on, the switching transistor Q + ,
Q2 is always off regardless of the pulse signal, and the air-fuel ratio control valve 34 is always maintained in the reset state, so the amount of air bleed is reduced and the air-fuel mixture is maintained in a richer state than normal. . The action will be explained below. First, in normal times when only the primary throttle valve 14 is operating and the secondary throttle valve 18 is not controlled by the secondary throttle valve control actuator 30, the opening detection switch 36 is activated. Never. Therefore, in this normal state, regular air-fuel ratio feedback control is performed, and the air-fuel ratio feedback control range in the low-speed and high-load range necessary for exhaust gas purification is expanded, thereby improving exhaust gas purification performance. On the other hand, when the secondary throttle valve 18 begins to be opened by the secondary throttle valve control actuator 30, the opening detection switch 36 is immediately activated and its contact 36A is opened. Then, since the switch S1 is turned on, the operation of the air-fuel ratio control valve 34 is stopped, and thereby,
The introduction of atmospheric air from the air-fuel ratio control valve 34 to the main air bleed passage 38 and the slow air bleed passage 40 is stopped, and the air-fuel ratio becomes smaller and becomes the output air-fuel ratio, improving output performance and acceleration performance. Ru. An example of the relationship between elapsed time and torque during full throttle acceleration in this embodiment is shown by a solid line in FIG. Compared to the conventional example also shown by the broken line A, the torque rises faster during full throttle acceleration,
Therefore, it is clear that acceleration performance is improved. In this embodiment, the feedback control of the air-fuel ratio is stopped when the opening degree of the secondary throttle valve 18 exceeds a set value, so the instant the secondary throttle valve 18 starts operating. can be reliably detected. Note that the method for detecting the operating state of the secondary throttle valve 18 is not limited to this, and for example, as shown by the broken line in FIG. A control negative pressure detection switch 100 is provided for detecting that the control negative pressure supplied to 30A has exceeded a set value,
It is also possible to open and close the switch S1 of the drive circuit 92 in accordance with the output of the negative pressure detection switch 100. In this case, the feedback control of the air-fuel ratio can be stopped at the point when the control negative pressure introduced into the diaphragm chamber 30A starts to increase, so that the secondary throttle valve 18 actually
Feedback control can be stopped just before the brake is opened, further improving acceleration performance. Further, in the embodiment described above, the air-fuel ratio feedback control was stopped by grounding the input signal of the switching transistor Q1 of the drive circuit 92 by the switch S1. The method of stopping the air-fuel ratio feedback control when the switch 100 is activated is not limited to this. For example, a switch S2 that short-circuits the feedback circuit of the integrating port 7 path 86 may be provided, thereby stopping the feedback control. It is possible. That is, in this case, switch S
2 is turned on, the capacitor C1 that determines the integral value constant of the integrating circuit 86 is short-circuited, and the output of the integrating circuit 86 becomes a constant value. Therefore, even if the output of the air-fuel ratio sensor 32 continues to be higher than the reference voltage Vo (over-rich mixture), the pulse width of the pulse signal will not increase beyond a certain value (proportional component), and therefore the mixture Qi is maintained in a more concentrated state than normal. Furthermore, in the above embodiment, the air-fuel ratio control valve 34 that controls air bleed is used as the air-fuel ratio control actuator, but the type of air-fuel ratio control actuator is not limited to this, and for example, It is also possible to use one that controls the fuel flow rate. [Effects of the Invention] As described above, according to the present invention, the low-speed, high-load air-fuel ratio feedback control range I required for exhaust gas purification is increased, and the exhaust gas purification performance is improved. In addition, when stopping the air-fuel ratio feedback at medium-high speeds and high loads, there is no need to use a delay time, so it is possible to quickly stop the feedback control, and it is possible to significantly improve the output performance at the start of acceleration, and therefore the acceleration performance. It has the excellent effect of

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

第１図は、従来例及び本発明における、空燃比フィード
バック制御停止線、空燃比フィードバック制御が必要な
領域及び出力性能上空燃比フィードバック制御が不要な
領域を比較して示す線図、第２図は、本発明に係る気化
器エンジンの空燃比制御装置の実施例の全体構成を示ず
ブロック線図、第３図は、前記実施例における気化器周
辺の詳細な構成を示す断面図、第４図は、前記実施例で
用いられでいる空燃比制御回路の構成を示す回路図、第
５図は、前記実施例及び従来例における、全開加速時の
トルクの立上り状態を比較して示づ線図である。 １０・・・２連式気化器、１４・・・１次側絞り弁、１
８・・・２次側絞り弁、 ３０・・・２次側絞り弁制御アクチュエータ、３２・・
・空燃比センサ、３４・・・空燃比制御弁、３６・・・
開度検出スイッチ、４２・・・空燃比制御回路、８６・
・・積分回路、　９２・・・駆動回路、Ｓｌ、Ｓ２・・
・スイッチ、 １００・・・制御圧検出スイッチ。 代理人　高　矢　論 （ほか１名）FIG. 1 is a diagram comparing the air-fuel ratio feedback control stop line, the region where air-fuel ratio feedback control is required, and the region where air-fuel ratio feedback control is unnecessary in terms of output performance in the conventional example and the present invention, and FIG. FIG. 3 is a block diagram showing the overall configuration of an embodiment of the air-fuel ratio control device for a carburetor engine according to the present invention; FIG. 3 is a sectional view showing the detailed configuration around the carburetor in the embodiment; FIG. 5 is a circuit diagram showing the configuration of the air-fuel ratio control circuit used in the above embodiment, and FIG. 5 is a diagram showing a comparison of the torque rise state during full throttle acceleration in the above embodiment and the conventional example. It is. 10...double carburetor, 14...primary side throttle valve, 1
8...Secondary side throttle valve, 30...Secondary side throttle valve control actuator, 32...
・Air-fuel ratio sensor, 34... Air-fuel ratio control valve, 36...
Opening detection switch, 42... air-fuel ratio control circuit, 86.
...Integrator circuit, 92...Drive circuit, Sl, S2...
・Switch, 100... Control pressure detection switch. Agent Takaya Ron (and 1 other person)

Claims (1)

【特許請求の範囲】[Claims] （１）常時作動する一次側絞り弁と、高負荷時にのみ開
かれる二次側絞り弁とを有する気化器エンジンの空燃比
制ｉ１１装置にＪゴいて、排気ガスの空燃比を検出する
ための空燃比センサと、エンジン燃焼至に吸入される混
合気の空燃比を制御するための空燃比副面アクチュエー
タと、二次側絞り弁の開度又は二次側絞り弁制田１アク
チュエータの制御負圧が設定値以上となったことを検出
するための開度又は制御負圧検出スイッチと、通常時は
、前記空燃比センサの出力に応じて、空燃比が設定値と
なるよう、前記空燃比制御アクチュエータをフィードバ
ック制御し、一方、前記開度又は制御負圧検出スイッチ
が作動しノζ時は、前記フィードバック制御を停止して
、空燃比が通常時より小となるよう、前記空燃比制御ア
クチュエータを制御する空燃比制御回路と、を備えたこ
とを特徴とする気化器エンジンの空燃比制御装置。(1) A method for detecting the air-fuel ratio of exhaust gas by using an air-fuel ratio control device for a carburetor engine that has a primary throttle valve that operates constantly and a secondary throttle valve that opens only when the load is high. An air-fuel ratio sensor, an air-fuel ratio side actuator for controlling the air-fuel ratio of the air-fuel mixture taken in during engine combustion, and a control device for controlling the opening of the secondary throttle valve or the secondary throttle valve control actuator. An opening or control negative pressure detection switch for detecting that the pressure has exceeded a set value, and a control device that normally adjusts the air-fuel ratio so that the air-fuel ratio reaches the set value according to the output of the air-fuel ratio sensor. The control actuator is feedback-controlled, and when the opening degree or control negative pressure detection switch is activated, the feedback control is stopped and the air-fuel ratio control actuator is controlled so that the air-fuel ratio is smaller than normal. An air-fuel ratio control device for a carburetor engine, comprising: an air-fuel ratio control circuit for controlling.
JP4259884A 1984-03-05 1984-03-05 Air-fuel ratio controlling apparatus for engine having carburetor Pending JPS60187749A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4259884A JPS60187749A (en) 1984-03-05 1984-03-05 Air-fuel ratio controlling apparatus for engine having carburetor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4259884A JPS60187749A (en) 1984-03-05 1984-03-05 Air-fuel ratio controlling apparatus for engine having carburetor

Publications (1)

Publication Number Publication Date
JPS60187749A true JPS60187749A (en) 1985-09-25

Family

ID=12640489

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4259884A Pending JPS60187749A (en) 1984-03-05 1984-03-05 Air-fuel ratio controlling apparatus for engine having carburetor

Country Status (1)

Country Link
JP (1) JPS60187749A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6255448A (en) * 1985-09-03 1987-03-11 Daihatsu Motor Co Ltd Air-fuel ratio controlling device for carburetor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6255448A (en) * 1985-09-03 1987-03-11 Daihatsu Motor Co Ltd Air-fuel ratio controlling device for carburetor

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