JP2002081339A - Air-fuel ratio control device of internal combustion engine - Google Patents
Air-fuel ratio control device of internal combustion engineInfo
- Publication number
- JP2002081339A JP2002081339A JP2000303146A JP2000303146A JP2002081339A JP 2002081339 A JP2002081339 A JP 2002081339A JP 2000303146 A JP2000303146 A JP 2000303146A JP 2000303146 A JP2000303146 A JP 2000303146A JP 2002081339 A JP2002081339 A JP 2002081339A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- air
- fuel ratio
- amount
- state quantity
- 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.)
- Granted
Links
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
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
-
- 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
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
- F02D41/0295—Control according to the amount of oxygen that is stored on the exhaust gas treating apparatus
-
- 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
- F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
- F02D41/1441—Plural sensors
-
- 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
-
- 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
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1409—Introducing closed-loop corrections characterised by the control or regulation method using at least a proportional, integral or derivative controller
-
- 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
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1413—Controller structures or design
- F02D2041/1422—Variable gain or coefficients
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/08—Exhaust gas treatment apparatus parameters
- F02D2200/0814—Oxygen storage amount
-
- 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
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
- F02D41/1456—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio with sensor output signal being linear or quasi-linear with the concentration of oxygen
-
- 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
- F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
- F02D41/187—Circuit arrangements for generating control signals by measuring intake air flow using a hot wire flow sensor
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Exhaust Gas After Treatment (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、触媒内の状態を考
慮して空燃比を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。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel ratio control device for an internal combustion engine that controls an air-fuel ratio in consideration of a state in a catalyst.
【０００２】[0002]
【従来の技術】近年の自動車は、排気管に三元触媒を設
置すると共に、この触媒の上流側に空燃比センサを設置
し、この空燃比センサの出力に基づいて排出ガスの空燃
比を触媒の浄化ウインドウ（理論空燃比付近）に制御す
るように燃料噴射量を制御することで、排出ガスを効率
良く浄化するようにしている。2. Description of the Related Art Recent automobiles have a three-way catalyst installed in an exhaust pipe and an air-fuel ratio sensor installed upstream of the catalyst, and the air-fuel ratio of exhaust gas is determined based on the output of the air-fuel ratio sensor. By controlling the fuel injection amount so as to control the purification window (around the stoichiometric air-fuel ratio), the exhaust gas is efficiently purified.
【０００３】[0003]
【発明が解決しようとする課題】ところで、触媒は、排
出ガス中のリーン成分（ＮＯｘ，Ｏ2 等）とリッチ成分
（ＨＣ，Ｈ2 等）とを酸化還元反応させて無害の中性ガ
ス成分（ＣＯ2 ，Ｈ2 Ｏ，Ｎ2 等）に変化させる他に、
未反応のリーン成分やリッチ成分を一時的に触媒内に吸
着する作用もあり、これら酸化還元反応と吸着作用の両
方によって排出ガスを浄化するものである。エンジン運
転状態によっては、触媒に流入する排出ガスの空燃比が
理論空燃比からリッチ側又はリーン側にずれた状態が暫
く続くことがあるが、このように空燃比がずれた状態が
暫く続くと、触媒内のリーン成分吸着量又はリッチ成分
吸着量が増加して飽和状態になることがあり、その結
果、触媒の吸着能力が低下して排出ガス浄化率が低下す
る不具合が発生する。[SUMMARY OF THE INVENTION Incidentally, the catalyst, the lean component (NOx, O 2, etc.) and the rich components (HC, H 2, etc.) harmless neutral gas components by oxidation-reduction reaction and in the exhaust gas (CO 2 , H 2 O, N 2 etc.)
The catalyst also has a function of temporarily adsorbing unreacted lean components and rich components into the catalyst, and purifies exhaust gas by both the oxidation-reduction reaction and the adsorption function. Depending on the engine operating state, the state in which the air-fuel ratio of the exhaust gas flowing into the catalyst deviates from the stoichiometric air-fuel ratio to the rich side or the lean side may continue for a while. In some cases, the amount of lean component adsorbed or the amount of rich component adsorbed in the catalyst increases, and the catalyst becomes saturated. As a result, there occurs a problem that the adsorption capacity of the catalyst is reduced and the exhaust gas purification rate is reduced.
【０００４】本発明はこのような事情を考慮してなされ
たものであり、従ってその目的は、触媒内の状態を考慮
して空燃比を適正に制御することで、排出ガス浄化率を
向上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。[0004] The present invention has been made in view of such circumstances, and accordingly, an object thereof is to improve the exhaust gas purification rate by appropriately controlling the air-fuel ratio in consideration of the state in the catalyst. An object of the present invention is to provide an air-fuel ratio control device for an internal combustion engine.
【０００５】[0005]
【課題を解決するための手段】上記目的を達成するため
に、本発明の請求項１の内燃機関の空燃比制御装置は、
触媒の上流又は下流の排出ガスの空燃比を空燃比検出手
段により検出すると共に、内燃機関に吸入される空気量
を空気量検出手段により検出し、検出した排出ガスの空
燃比と空気量とに基づいて触媒内状態量を触媒内状態量
算出手段により算出し、この触媒内状態量と目標値との
偏差が小さくなるように燃料噴射量を噴射制御手段によ
り補正する。このようにすれば、触媒の吸着能力ができ
るだけ良好に維持されるように制御され、排出ガス浄化
率が向上する。In order to achieve the above object, an air-fuel ratio control apparatus for an internal combustion engine according to a first aspect of the present invention is provided.
The air-fuel ratio of the exhaust gas upstream or downstream of the catalyst is detected by the air-fuel ratio detecting means, and the amount of air taken into the internal combustion engine is detected by the air amount detecting means. The in-catalyst state quantity is calculated by the in-catalyst state quantity calculation means on the basis of this, and the fuel injection amount is corrected by the injection control means so that the deviation between the in-catalyst state quantity and the target value is reduced. By doing so, the catalyst is controlled so that the adsorption capacity of the catalyst is maintained as good as possible, and the exhaust gas purification rate is improved.
【０００６】この場合、触媒内状態量は排出ガスの空燃
比と空気量とに基づいて算出されるが、空気量を検出す
る位置（吸気管）と排出ガスの空燃比を検出する位置
（排気管）とが離れているため、空気量検出位置を通過
した空気が噴射燃料と混合して燃焼して空燃比検出位置
に到達するまでに時間遅れが生じる。このため、空気量
が変化する過渡運転時には、同時刻に検出した空燃比と
空気量を用いたのでは触媒内状態量を正確に算出するこ
とができない。[0006] In this case, the state quantity in the catalyst is calculated based on the air-fuel ratio of the exhaust gas and the air amount, and a position for detecting the air amount (intake pipe) and a position for detecting the air-fuel ratio of the exhaust gas (exhaust gas). Because of the distance from the tube, the air that has passed through the air amount detection position mixes with the injected fuel and burns, and a time delay occurs before reaching the air-fuel ratio detection position. Therefore, during the transient operation in which the air amount changes, the state quantity in the catalyst cannot be accurately calculated by using the air-fuel ratio and the air amount detected at the same time.
【０００７】そこで、請求項２のように、触媒内状態量
を算出する際に用いる空気量は、少なくとも燃料噴射か
ら排出ガスの空燃比を検出するまでの遅れ時間分過去の
空気量を用いると良い。このようにすれば、触媒内状態
量を算出する際に用いる空気量と空燃比との時間的なず
れを修正することができ、空気量が変化する過渡運転時
でも触媒内状態量を精度良く算出することができる。Therefore, the amount of air used in calculating the state quantity in the catalyst may be at least the amount of air in the past corresponding to the delay time from the fuel injection to the detection of the air-fuel ratio of the exhaust gas. good. With this configuration, it is possible to correct a time lag between the air amount and the air-fuel ratio used when calculating the state amount in the catalyst, and accurately determine the state amount in the catalyst even during a transient operation in which the air amount changes. Can be calculated.
【０００８】また、請求項３のように、所定の演算周期
で目標空燃比に対する排出ガスの空燃比のずれ量と空気
量とに基づいて触媒内状態量の変化量を算出し、この変
化量を積算して現在の触媒内状態量を求めるようにして
も良い。このようにすれば、簡単な演算処理で触媒内状
態量を精度良く算出することができる。According to a third aspect of the present invention, a change amount of the state quantity in the catalyst is calculated based on a deviation amount of the air-fuel ratio of the exhaust gas with respect to the target air-fuel ratio and an air amount in a predetermined calculation cycle. May be integrated to obtain the current state quantity in the catalyst. In this way, the in-catalyst state quantity can be accurately calculated by a simple calculation process.
【０００９】また、触媒内状態量が触媒の飽和吸着量に
達すると、それ以上はガス成分を吸着できなくなるた
め、請求項４のように、触媒内状態量の算出値をガード
処理手段によって触媒の飽和吸着量に相当するガード値
で制限するようにすると良い。このようにすれば、触媒
が飽和状態になったときに触媒内状態量の算出値の誤差
が拡大することを防止することができる。Further, when the state quantity in the catalyst reaches the saturated adsorption amount of the catalyst, no more gas components can be adsorbed, so that the calculated value of the state quantity in the catalyst is determined by the guard processing means. Is preferably limited by a guard value corresponding to the saturated adsorption amount of. In this way, it is possible to prevent the error in the calculated value of the in-catalyst state quantity from increasing when the catalyst becomes saturated.
【００１０】この場合、触媒内を流れる排出ガスの流速
が速くなるほど（空気量が多くなるほど）、触媒の飽和
吸着量が少なくなるという飽和吸着特性があるため、請
求項５のように、触媒内状態量の算出値に対するガード
値を空気量に応じて変化させるようにしても良い。この
ようにすれば、実際の触媒の飽和吸着特性に適合したガ
ード値を設定することができ、触媒内状態量の算出精度
を更に向上することができる。In this case, the catalyst has a saturated adsorption characteristic in which the higher the flow rate of the exhaust gas flowing through the catalyst (the larger the amount of air), the smaller the saturated adsorption amount of the catalyst. The guard value for the calculated value of the state amount may be changed according to the air amount. In this way, a guard value suitable for the actual saturated adsorption characteristics of the catalyst can be set, and the accuracy of calculating the state quantity in the catalyst can be further improved.
【００１１】尚、排出ガスの空燃比とガス濃度とは相関
関係があるため、請求項６のように触媒の上流又は下流
の排出ガスのガス濃度をガス濃度検出手段により検出す
ると共に、内燃機関に吸入される空気量を空気量検出手
段により検出し、検出した排出ガスのガス濃度と空気量
とに基づいて触媒内状態量を算出し、この触媒内状態量
と目標値との偏差が小さくなるように燃料噴射量を補正
するようにしても良い。このようにしても、請求項１と
同じく、触媒の吸着能力ができるだけ良好に維持される
ように制御され、排出ガス浄化率が向上する。Since there is a correlation between the air-fuel ratio of the exhaust gas and the gas concentration, the gas concentration of the exhaust gas upstream or downstream of the catalyst is detected by the gas concentration detecting means and the internal combustion engine is detected. The amount of air sucked into the air is detected by the air amount detecting means, and the state amount in the catalyst is calculated based on the detected gas concentration of the exhaust gas and the air amount, and the deviation between the state amount in the catalyst and the target value is small. The fuel injection amount may be corrected so as to be as follows. Also in this case, similarly to the first aspect, the catalyst is controlled so that the adsorption capacity of the catalyst is maintained as good as possible, and the exhaust gas purification rate is improved.
【００１２】ところで、触媒内状態量を算出する際に、
ある程度の誤差が生じることは避けられない。この触媒
内状態量の算出誤差（推定誤差）は、触媒下流側に設置
した空燃比センサ（又は酸素センサ）の出力を触媒上流
側の目標空燃比に反映させるサブフィードバックにより
補正できるが、サブフィードバックによる補正は、応答
遅れがある。By the way, when calculating the state quantity in the catalyst,
It is inevitable that some error will occur. This calculation error (estimation error) of the in-catalyst state quantity can be corrected by sub-feedback that reflects the output of the air-fuel ratio sensor (or oxygen sensor) installed on the downstream side of the catalyst to the target air-fuel ratio on the upstream side of the catalyst. Correction has a response delay.
【００１３】そこで、請求項７のように、触媒内状態量
を算出する際に、その算出値を実際の触媒内状態量に応
じて補正手段によって補正するようにしても良い。この
ようにすれば、触媒内状態量の算出誤差（推定誤差）を
少なくすることができ、その分、実際の触媒内状態量に
対する応答性の良い空燃比制御を実施することができ、
過渡時の排出ガス浄化性能を向上することができる。Therefore, when calculating the state quantity in the catalyst, the calculated value may be corrected by the correction means according to the actual state quantity in the catalyst. In this way, the calculation error (estimation error) of the in-catalyst state quantity can be reduced, and the air-fuel ratio control with good responsiveness to the actual in-catalyst state quantity can be implemented accordingly.
Exhaust gas purification performance during transition can be improved.
【００１４】この場合、実際の触媒内状態量に応じて、
触媒から流出する排出ガスの空燃比又はガス濃度が変化
する特性があるため、請求項８のように、実際の触媒内
状態量の情報は、触媒から流出する排出ガスの空燃比又
はガス濃度を検出する触媒下流側のセンサの出力を用い
るようにすれば良い。これにより、触媒下流側のセンサ
の出力から実際の触媒内状態量の情報を簡単に得ること
ができる。In this case, according to the actual state quantity in the catalyst,
Since there is a characteristic that the air-fuel ratio or the gas concentration of the exhaust gas flowing out of the catalyst changes, the information on the actual state quantity in the catalyst indicates the air-fuel ratio or the gas concentration of the exhaust gas flowing out of the catalyst. What is necessary is just to use the output of the sensor downstream of the catalyst to be detected. This makes it possible to easily obtain information on the actual state quantity in the catalyst from the output of the sensor on the downstream side of the catalyst.
【００１５】また、請求項９のように、触媒内状態量算
出手段により算出した触媒内状態量と実際の触媒内状態
量との偏差に応じて、触媒内状態量の目標値を制御する
パラメータをパラメータ可変手段により可変するように
しても良い。これにより、触媒内状態量の目標値を触媒
内状態量の偏差に応じて応答性良く設定することができ
る。A parameter for controlling a target value of the in-catalyst state quantity according to a deviation between the in-catalyst state quantity calculated by the in-catalyst state quantity calculation means and the actual in-catalyst state quantity. May be varied by parameter varying means. Thereby, the target value of the in-catalyst state quantity can be set with good responsiveness according to the deviation of the in-catalyst state quantity.
【００１６】この場合、請求項１０のように、触媒内状
態量の目標値を制御するパラメータとして、触媒内状態
量を算出する式のパラメータを可変するようにしても良
く、或は、請求項１１のように、触媒下流側の空燃比を
前記目標値に反映させるサブフィードバックの制御パラ
メータを可変するようにしても良い。いずれの方法で
も、触媒内状態量の目標値を触媒内状態量の偏差に応じ
て応答性良く可変することができる。In this case, as a parameter for controlling the target value of the in-catalyst state quantity, a parameter of an equation for calculating the in-catalyst state quantity may be varied. As in 11, the sub-feedback control parameter for reflecting the air-fuel ratio on the downstream side of the catalyst to the target value may be varied. In either method, the target value of the in-catalyst state quantity can be varied with high responsiveness in accordance with the deviation of the in-catalyst state quantity.
【００１７】また、実際の触媒内状態量の情報にもある
程度の誤差があることを考慮して、請求項１２のよう
に、触媒内状態量算出手段により算出した触媒内状態量
と実際の触媒内状態量との偏差が所定値以下の場合に、
該偏差を０と見なすようにしても良い。このようにすれ
ば、実際の触媒内状態量の情報（触媒下流側のセンサの
出力）に含まれる誤差による過補正を回避することがで
き、安定した空燃比制御を行うことができる。Also, in consideration of the fact that there is a certain error in the information on the actual state quantity in the catalyst, the catalyst state quantity calculated by the catalyst state quantity calculating means and the actual catalyst state quantity are calculated. When the deviation from the internal state quantity is equal to or less than the predetermined value,
The deviation may be regarded as 0. By doing so, it is possible to avoid overcorrection due to an error included in the information on the actual in-catalyst state quantity (output of the sensor on the downstream side of the catalyst), and to perform stable air-fuel ratio control.
【００１８】[0018]
【発明の実施の形態】［実施形態（１）］以下、本発明
の実施形態（１）を図１乃至図５に基づいて説明する。[Embodiment (1)] An embodiment (1) of the present invention will be described below with reference to FIGS.
【００１９】まず、図１に基づいてエンジン制御システ
ム全体の概略構成を説明する。内燃機関であるエンジン
１１の吸気管１２の最上流部には、エアクリーナ１３が
設けられ、このエアクリーナ１３の下流側には、吸入空
気量を検出するエアフローメータ１４（空気量検出手
段）が設けられている。このエアフローメータ１４の下
流側には、スロットルバルブ１５とスロットル開度を検
出するスロットル開度センサ１６とが設けられている。First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of an engine 11 which is an internal combustion engine, and an air flow meter 14 (air amount detecting means) for detecting an intake air amount is provided downstream of the air cleaner 13. ing. Downstream of the air flow meter 14, a throttle valve 15 and a throttle opening sensor 16 for detecting a throttle opening are provided.
【００２０】更に、スロットルバルブ１５の下流側に
は、サージタンク１７が設けられ、このサージタンク１
７に、吸気管圧力を検出する吸気管圧力センサ１８が設
けられている。また、サージタンク１７には、エンジン
１１の各気筒に空気を導入する吸気マニホールド１９が
設けられ、各気筒の吸気マニホールド１９の吸気ポート
近傍に、それぞれ燃料を噴射する燃料噴射弁２０が取り
付けられている。Further, on the downstream side of the throttle valve 15, a surge tank 17 is provided.
7, an intake pipe pressure sensor 18 for detecting an intake pipe pressure is provided. Further, the surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached near an intake port of the intake manifold 19 of each cylinder. I have.
【００２１】一方、エンジン１１の排気管２１の途中に
は、排ガス中の有害成分（ＣＯ，ＨＣ，ＮＯｘ等）を低
減させる三元触媒等の触媒２２が設置されている。この
触媒２２の上流側には、排出ガスの空燃比を検出するリ
ニアＡ／Ｆセンサ等の空燃比センサ２３（空燃比検出手
段）が設けられている。また、エンジン１１のシリンダ
ブロックには、冷却水温を検出する冷却水温センサ２４
や、エンジン回転速度を検出するクランク角センサ２５
が取り付けられている。On the other hand, a catalyst 22 such as a three-way catalyst for reducing harmful components (CO, HC, NOx, etc.) in exhaust gas is provided in the exhaust pipe 21 of the engine 11. An air-fuel ratio sensor 23 (air-fuel ratio detecting means) such as a linear A / F sensor for detecting the air-fuel ratio of the exhaust gas is provided upstream of the catalyst 22. A cooling water temperature sensor 24 for detecting a cooling water temperature is provided in a cylinder block of the engine 11.
And a crank angle sensor 25 for detecting the engine speed.
Is attached.
【００２２】これら各種のセンサ出力は、エンジン制御
回路（以下「ＥＣＵ」と表記する）２６に入力される。
このＥＣＵ２６は、マイクロコンピュータを主体として
構成され、内蔵されたＲＯＭ（記憶媒体）に記憶された
図２及び図３の目標φ算出プログラムを実行すること
で、触媒内状態量ＯＳを算出し、この触媒内状態量ＯＳ
に応じて触媒２２上流側の目標燃料過剰率φref を算出
する。ここで、燃料過剰率φは、空気過剰率λの逆数で
あり（φ＝１／λ）、空気過剰率λは、実空燃比と理論
空燃比との比である。 λ＝実空燃比／理論空燃比 φ＝理論空燃比／実空燃比These various sensor outputs are input to an engine control circuit (hereinafter referred to as "ECU") 26.
The ECU 26 is configured mainly by a microcomputer, and executes the target φ calculation program of FIGS. 2 and 3 stored in a built-in ROM (storage medium) to calculate the state quantity OS in the catalyst. OS in the catalyst
The target excess fuel ratio φref on the upstream side of the catalyst 22 is calculated in accordance with the above equation. Here, the excess fuel ratio φ is the reciprocal of the excess air ratio λ (φ = 1 / λ), and the excess air ratio λ is the ratio between the actual air-fuel ratio and the stoichiometric air-fuel ratio. λ = actual air-fuel ratio / stoichiometric air-fuel ratio φ = stoichiometric air-fuel ratio / actual air-fuel ratio
【００２３】ＥＣＵ２６は、図２及び図３の目標φ算出
プログラムで算出した目標燃料過剰率φref と実際の燃
料過剰率φとの偏差を小さくするように燃料噴射量をフ
ィードバック補正して、触媒内状態量ＯＳを目標触媒内
状態量ＯＳref 付近に制御する。この機能が特許請求の
範囲でいう噴射制御手段に相当する。The ECU 26 performs feedback correction of the fuel injection amount so as to reduce the deviation between the target excess fuel ratio φref calculated by the target φ calculation program shown in FIGS. The state quantity OS is controlled near the target in-catalyst state quantity OSref. This function corresponds to the injection control means in the claims.
【００２４】図２及び図３の目標φ算出プログラムは、
所定クランク角毎（例えば１８０℃Ａ毎）又は所定時間
毎に起動され、まず、ステップ１０１で、次のようにし
て現在の触媒内状態量ＯＳ(i) を算出する。まず、触媒
２２上流側の空燃比センサ２３で検出した実際の燃料過
剰率φと目標燃料過剰率φref との偏差（φ−φref）
と、単位時間当たり触媒２２に流入する空気量Ｑとに基
づいて触媒内状態量の変化量ΔＯＳ(i) を算出する。 ΔＯＳ(i) ＝（φ−φref ）×Ｑ(i-d) ……（１）The target φ calculation program shown in FIGS.
It is started every predetermined crank angle (for example, every 180 ° C.) or every predetermined time. First, in step 101, the current state quantity OS (i) in the catalyst is calculated as follows. First, a deviation (φ−φref) between the actual excess fuel ratio φ detected by the air-fuel ratio sensor 23 on the upstream side of the catalyst 22 and the target excess fuel ratio φref.
Then, the amount of change ΔOS (i) of the state quantity in the catalyst is calculated based on the amount of air Q flowing into the catalyst 22 per unit time. ΔOS (i) = (φ−φref) × Q (id) (1)
【００２５】ここで、空気量Ｑは、燃料噴射から排出ガ
スの燃料過剰率φを検出するまでの遅れ時間ｄを考慮し
て、現時点ｉよりも遅れ時間ｄ前の過去の空気量Ｑ(i-
d) を用いる。この際、遅れ時間ｄは、演算処理を簡単
にするために固定値としても良いが、空気量Ｑに応じて
遅れ時間ｄを変化させても良い。つまり、空気量Ｑが多
くなるほど、空気の流速が速くなって実際の遅れ時間ｄ
が短くなるため、空気量Ｑが多くなるほど、遅れ時間ｄ
を短くするように設定しても良い。Here, in consideration of the delay time d from the fuel injection to the detection of the excess fuel ratio φ of the exhaust gas, the air amount Q is calculated based on the past air amount Q (i -
Use d). At this time, the delay time d may be a fixed value in order to simplify the arithmetic processing, but the delay time d may be changed according to the air amount Q. That is, as the air amount Q increases, the air flow velocity increases and the actual delay time d
Becomes shorter, the delay time d increases as the air amount Q increases.
May be set to be shorter.
【００２６】上記（１）式で算出した触媒内状態量の変
化量ΔＯＳ(i) を前回の触媒内状態量算出値ＯＳ(i-1)
に積算して現在の触媒内状態量ＯＳ(i) を求める。 ＯＳ(i) ＝ΔＯＳ(i) ＋ＯＳ(i-1) ……（２） このステップ１０１の処理が特許請求の範囲でいう触媒
内状態量算出手段としての役割を果たす。The change amount ΔOS (i) of the in-catalyst state amount calculated by the above equation (1) is used as the previous in-catalyst state amount calculation value OS (i-1).
To obtain the current state quantity OS (i) in the catalyst. OS (i) = ΔOS (i) + OS (i-1) (2) The process of step 101 plays a role as an in-catalyst state quantity calculating means described in the claims.
【００２７】その後、ステップ１０２に進み、触媒内状
態量ＯＳ(i) の算出値を触媒２２のリーン側／リッチ側
飽和吸着量に相当するガード値ＯＳmin ，ＯＳmax でガ
ード処理する。例えば、触媒内状態量ＯＳ(i) の算出値
がガード値ＯＳmin ，ＯＳmax の範囲内（ＯＳmin ≦Ｏ
Ｓ(i) ≦ＯＳmax ）であれば、触媒内状態量ＯＳ(i)の
算出値をそのまま採用し、触媒内状態量ＯＳ(i) の算出
値がガード値ＯＳmin（又はＯＳmax ）を越えていれ
ば、触媒内状態量ＯＳ(i) の算出値をガード値ＯＳmin
（又はＯＳmax ）に置き換えて、ＯＳ(i) ＝ＯＳmin
（又はＯＳ(i) ＝ＯＳmax ）とする。この処理が特許請
求の範囲でいうガード処理手段としての役割を果たす。Thereafter, the routine proceeds to step 102, where the calculated value of the in-catalyst state quantity OS (i) is subjected to guard processing with guard values OSmin, OSmax corresponding to the lean / rich saturated adsorption amount of the catalyst 22. For example, if the calculated value of the state quantity OS (i) in the catalyst falls within the range of the guard values OSmin and OSmax (OSmin ≦ O
If S (i) ≦ OSmax), the calculated value of the in-catalyst state quantity OS (i) is adopted as it is, and the calculated value of the in-catalyst state quantity OS (i) exceeds the guard value OSmin (or OSmax). If the calculated value of the in-catalyst state quantity OS (i) is
(Or OSmax), OS (i) = OSmin
(Or OS (i) = OSmax). This processing serves as a guard processing means referred to in the claims.
【００２８】この際、ガード値ＯＳmin ，ＯＳmax は、
演算処理を簡単にするために固定値としても良いが、触
媒２２内を流れる排出ガスの流速が速くなるほど（空気
量Ｑが多くなるほど）、触媒２２の飽和吸着量が少なく
なるという飽和吸着特性があるため、図４に示すよう
に、ガード値ＯＳmin ，ＯＳmax を空気量Ｑに応じてマ
ップ等で変化させるようにしても良い。この場合は、空
気量Ｑが多くなるほど、ガード値ＯＳmin ，ＯＳmax が
小さくなるように設定すると良い。このようにすれば、
実際の触媒２２の飽和吸着特性に適合したガード値ＯＳ
min ，ＯＳmax を設定することができる。At this time, the guard values OSmin and OSmax are:
Although a fixed value may be used to simplify the arithmetic processing, the saturated adsorption characteristic that the saturated adsorption amount of the catalyst 22 decreases as the flow velocity of the exhaust gas flowing in the catalyst 22 increases (the air amount Q increases). Therefore, as shown in FIG. 4, the guard values OSmin and OSmax may be changed on a map or the like according to the air amount Q. In this case, the guard values OSmin and OSmax may be set to be smaller as the air amount Q increases. If you do this,
Guard value OS suitable for the saturated adsorption characteristics of the actual catalyst 22
min and OSmax can be set.
【００２９】その後、ステップ１０３に進み、目標触媒
内状態量ＯＳref と現在の触媒内状態量ＯＳ(i) との偏
差ＯＳerror を算出する。 ＯＳerror ＝ＯＳref −ＯＳ(i)Thereafter, the routine proceeds to step 103, where a deviation OSerror between the target in-catalyst state quantity OSref and the current in-catalyst state quantity OS (i) is calculated. OSerror = OSref-OS (i)
【００３０】そして、次のステップ１０４で、ＰＩＤコ
ントローラの比例ゲインｋｐ、積分ゲインｋｉ、微分ゲ
インｋｄをマップ等により設定する。この際、各ゲイン
ｋｐ，ｋｉ，ｋｄを吸入空気量又は吸気管圧力等のエン
ジン運転条件に応じて可変しても良い。In the next step 104, the proportional gain kp, the integral gain ki, and the differential gain kd of the PID controller are set by using a map or the like. At this time, each of the gains kp, ki, kd may be varied according to engine operating conditions such as the intake air amount or the intake pipe pressure.
【００３１】この後、ステップ１０５に進み、各ゲイン
ｋｐ，ｋｉ，ｋｄと演算間隔ｄｔ（例えば１８０℃Ａ回
転するのに要する時間）を用いて、ＰＩＤコントローラ
の制御パラメータＡ１，Ａ２，Ｂ１，Ｂ２，Ｂ３を次式
により算出する。 Ａ１＝１ Ａ２＝０ Ｂ１＝ｋｐ・（１＋ｄｔ／ｋｉ＋ｋｄ／ｄｔ） Ｂ２＝ｋｐ・（１＋２・ｋｄ／ｄｔ） Ｂ３＝ｋｐ・ｋｄ／ｄｔThereafter, the routine proceeds to step 105, where the control parameters A1, A2, B1, B2 of the PID controller are calculated using the gains kp, ki, kd and the calculation interval dt (for example, the time required for rotating at 180 ° C. A). , B3 are calculated by the following equations. A1 = 1 A2 = 0 B1 = kp · (1 + dt / ki + kd / dt) B2 = kp · (1 + 2 · kd / dt) B3 = kp · kd / dt
【００３２】この後、図３のステップ１０６に進み、上
記各制御パラメータＡ１，Ａ２，Ｂ１，Ｂ２，Ｂ３と触
媒内状態量偏差ＯＳerror と過去の目標燃料過剰率φre
f を用いて今回の目標燃料過剰率φref を次のようにし
て算出する。まず、目標燃料過剰率補正量Δφref を次
式により算出する。 Δφref ＝Ｂ１・ＯＳerror(i)−Ｂ２・ＯＳerror(i-1)
＋Ｂ３・ＯＳerror(i-2)＋Ａ１・φref (i-1) −Ａ２・
φref (i-2)Thereafter, the routine proceeds to step 106 in FIG. 3, where the control parameters A1, A2, B1, B2, and B3, the in-catalyst state deviation OSerror, and the past target excess fuel ratio φre
Using f, the present target excess fuel ratio φref is calculated as follows. First, the target excess fuel ratio correction amount Δφref is calculated by the following equation. Δφref = B1 · OSerror (i) −B2 · OSerror (i-1)
+ B3 · OSerror (i-2) + A1 · φref (i-1) -A2 ·
φref (i-2)
【００３３】そして、この目標燃料過剰率補正量Δφre
f をベース値“１”に加算して、触媒２２上流側の目標
燃料過剰率φref を求めて、本プログラムを終了する。 φref ＝１＋ΔφrefThen, the target excess fuel ratio correction amount Δφre
By adding f to the base value “1”, the target excess fuel ratio φref on the upstream side of the catalyst 22 is obtained, and the program is terminated. φref = 1 + Δφref
【００３４】次に、図５に基づいて、過渡運転時の燃料
過剰率φと触媒内状態量ＯＳの挙動の一例を説明する。
例えば、触媒２２上流側の燃料過剰率φがリッチ側に変
化すると、触媒２２内にリッチ成分が吸着されて触媒内
状態量ＯＳが増加する。しかし、触媒内状態量ＯＳがリ
ッチ側のガード値ＯＳmax （リッチ側の飽和吸着量）に
達すると、それ以上はリッチ成分を吸着できなくなるた
め、触媒内状態量ＯＳの算出値がガード値ＯＳmax でガ
ード処理され、触媒内状態量ＯＳの算出値がガード値Ｏ
Ｓmax に張り付いた状態となる。これにより、触媒２２
が飽和状態になったときに触媒内状態量ＯＳの算出値の
誤差が拡大することが防止される。Next, an example of the behavior of the excess fuel ratio φ and the state quantity OS in the catalyst during the transient operation will be described with reference to FIG.
For example, when the excess fuel ratio φ on the upstream side of the catalyst 22 changes to the rich side, a rich component is adsorbed in the catalyst 22 and the state amount OS in the catalyst increases. However, when the in-catalyst state amount OS reaches the rich side guard value OSmax (rich side saturated adsorption amount), the rich component cannot be adsorbed any more, and the calculated value of the in-catalyst state amount OS becomes the guard value OSmax. The guard process is performed, and the calculated value of the state quantity OS in the catalyst is changed to the guard value O.
It is in a state of sticking to Smax. Thereby, the catalyst 22
Is increased, the error in the calculated value of the in-catalyst state quantity OS is prevented from increasing.
【００３５】その後、燃料過剰率φがリーン側に変化す
ると、触媒２２内に吸着されていたリッチ成分が排出ガ
ス中のリーン成分と酸化還元反応して消費されるため、
触媒内状態量ＯＳが減少し始める。これにより、触媒内
状態量ＯＳが目標触媒内状態量ＯＳref 付近に戻され
る。その結果、触媒２２の吸着能力が良好に維持され、
排出ガス浄化率が向上する。Thereafter, when the excess fuel ratio φ changes to the lean side, the rich component adsorbed in the catalyst 22 is consumed by an oxidation-reduction reaction with the lean component in the exhaust gas.
The state quantity OS in the catalyst starts to decrease. As a result, the in-catalyst state quantity OS is returned to the vicinity of the target in-catalyst state quantity OSref. As a result, the adsorption capacity of the catalyst 22 is favorably maintained,
The exhaust gas purification rate is improved.
【００３６】ところで、本実施形態（１）では、触媒内
状態量ＯＳを排出ガスの燃料過剰率φと空気量Ｑとに基
づいて算出するが、空気量Ｑを検出する位置（吸気管１
２）と排出ガスの燃料過剰率φを検出する位置（排気管
２１）とが離れているため、空気量検出位置を通過した
空気が噴射燃料と混合して燃焼して燃料過剰率φの検出
位置に到達するまでに時間遅れが生じる。このため、空
気量Ｑが変化する過渡運転時には、同時刻に検出した燃
料過剰率φ(i) と空気量Ｑ(i) を用いたのでは触媒内状
態量ＯＳを正確に算出することができない。In this embodiment (1), the state quantity OS in the catalyst is calculated based on the excess fuel ratio φ of the exhaust gas and the air amount Q.
2) and the position for detecting the excess fuel ratio φ of the exhaust gas (exhaust pipe 21) is separated, so that the air passing through the air amount detection position mixes with the injected fuel and burns to detect the excess fuel ratio φ. There is a time delay before reaching the position. Therefore, during the transient operation in which the air amount Q changes, the in-catalyst state amount OS cannot be accurately calculated by using the excess fuel ratio φ (i) and the air amount Q (i) detected at the same time. .
【００３７】そこで、本実施形態（１）では、触媒内状
態量ＯＳを算出する際に用いる空気量は、燃料噴射から
排出ガスの燃料過剰率φを検出するまでの遅れ時間ｄを
考慮して、現時点ｉよりも遅れ時間ｄ前の過去の空気量
Ｑ(i-d) を用いる。これにより、触媒内状態量ＯＳを算
出する際に用いる空気量Ｑと燃料過剰率φとの時間的な
ずれを修正することができ、空気量Ｑが変化する過渡運
転時でも触媒内状態量を精度良く算出することができ
る。Therefore, in the present embodiment (1), the amount of air used in calculating the in-catalyst state amount OS is determined in consideration of the delay time d from the fuel injection to the detection of the excess fuel ratio φ of the exhaust gas. , The past air amount Q (id) before the delay time d before the current time i is used. This makes it possible to correct the time lag between the air amount Q used in calculating the in-catalyst state amount OS and the excess fuel ratio φ, and to reduce the in-catalyst state amount even during the transient operation in which the air amount Q changes. It can be calculated with high accuracy.
【００３８】尚、本実施形態（１）では、燃料噴射から
排出ガスの燃料過剰率φを検出するまでの遅れ時間ｄを
考慮したが、空気が空気量検出位置から燃料過剰率φの
検出位置に到達するまでの遅れ時間ｄ’を考慮して、現
時点ｉよりも遅れ時間ｄ’前の過去の空気量Ｑ(i-d')を
用いるようにしても良く、要は、少なくとも燃料噴射か
ら排出ガスの燃料過剰率φを検出するまでの遅れ時間分
過去の空気量を用いるようにすれば良い。In this embodiment (1), the delay time d from the fuel injection to the detection of the excess fuel ratio φ of the exhaust gas is taken into consideration. May be used in consideration of the delay time d 'to reach the current time, and the past air amount Q (i-d') before the delay time d 'before the current time i may be used. The amount of air in the past corresponding to the delay time until the detection of the excess fuel ratio φ of the exhaust gas may be used.
【００３９】また、本実施形態（１）では、ＰＩＤコン
トローラを用いて制御パラメータＡ１，Ａ２，Ｂ１，Ｂ
２，Ｂ３を算出するようにしたが、図６に示す本発明の
他の実施形態では、ＰＩＤコントローラの代わりに、近
似微分を用いて制御パラメータＡ１，Ａ２，Ｂ１，Ｂ
２，Ｂ３を算出するようにしている。その他の処理は、
図２及び図３の各ステップの処理と同じで良い。このよ
うに、近似微分を用いて制御パラメータＡ１，Ａ２，Ｂ
１，Ｂ２，Ｂ３を算出しても、前記実施形態とほぼ同様
の効果を得ることができる。In this embodiment (1), the control parameters A1, A2, B1, B
2, B3 is calculated, but in another embodiment of the present invention shown in FIG. 6, the control parameters A1, A2, B1, B are obtained by using approximate differentiation instead of the PID controller.
2 and B3 are calculated. Other processing,
The processing may be the same as the processing in each step of FIGS. Thus, the control parameters A1, A2, B
Even if 1, B2 and B3 are calculated, substantially the same effects as in the above embodiment can be obtained.
【００４０】図１に示すシステム構成例では、触媒２２
の上流側のみに空燃比センサ２３を設置したが、触媒２
２の上流側と下流側の両方に空燃比センサを設置したシ
ステムにも本発明を適用できる。この場合、触媒下流側
の空燃比センサで検出した燃料過剰率と空気量とに基づ
いて触媒内状態量を算出し、この触媒内状態量と目標触
媒内状態量との偏差を小さくするように触媒上流側の目
標燃料過剰率を算出するようにしても良い。この際、触
媒内状態量の算出に用いる空気量は、少なくとも燃料噴
射から触媒下流側で排出ガスの燃料過剰率を検出するま
での遅れ時間を考慮して、その遅れ時間分過去の空気量
を用いるようにすると良い。In the example of the system configuration shown in FIG.
The air-fuel ratio sensor 23 is installed only on the upstream side of
The present invention can also be applied to a system in which an air-fuel ratio sensor is installed on both the upstream side and the downstream side. In this case, the in-catalyst state amount is calculated based on the excess fuel ratio and the air amount detected by the air-fuel ratio sensor on the downstream side of the catalyst, and the deviation between the in-catalyst state amount and the target in-catalyst state amount is reduced. The target excess fuel ratio on the upstream side of the catalyst may be calculated. At this time, the amount of air used for calculating the state quantity in the catalyst is calculated based on at least the delay time from the fuel injection to the detection of the excess fuel ratio of the exhaust gas on the downstream side of the catalyst. It is good to use.
【００４１】また、上記各実施形態においては、空燃比
の情報として燃料過剰率φを用いたが、燃料過剰率φに
代えて、空気過剰率λ又は空燃比Ａ／Ｆを用いても良い
ことは言うまでもない。Further, in each of the above embodiments, the excess fuel ratio φ is used as the information of the air-fuel ratio, but the excess fuel ratio λ or the air-fuel ratio A / F may be used instead of the excess fuel ratio φ. Needless to say.
【００４２】また、空燃比センサ２３の代わりに、排出
ガスのガス濃度を検出するガス濃度センサを用いても良
い。この場合は、検出した排出ガスのガス濃度と空気量
とに基づいて触媒内状態量を算出し、この触媒内状態量
と目標値との偏差が小さくなるように燃料噴射量を補正
するようにすれば良い。Further, instead of the air-fuel ratio sensor 23, a gas concentration sensor for detecting the gas concentration of the exhaust gas may be used. In this case, the state quantity in the catalyst is calculated based on the detected gas concentration of the exhaust gas and the air amount, and the fuel injection amount is corrected so that the deviation between the state quantity in the catalyst and the target value is reduced. Just do it.
【００４３】［実施形態（２）］次に、図７乃至図１０
に基づいて本発明の実施形態（２）を説明する。本実施
形態（２）では、触媒２２の上流側と下流側の両方に空
燃比センサ２３，２７を設置している。上流側の空燃比
センサ（以下「上流側センサ」という）２３は、前記実
施形態（１）と同じく、排出ガスの空燃比に応じてリニ
アな空燃比信号を出力するリニアＡ／Ｆセンサ等が用い
られ、下流側の空燃比センサ（以下「下流側センサ」と
いう）２７は、排出ガスの空燃比のリッチ／リーンに応
じて出力電圧が反転する酸素センサ等が用いられてい
る。尚、下流側センサ２７も、上流側センサ２３と同じ
く、リニアＡ／Ｆセンサ等を用いても良いことは言うま
でもない。その他のシステム構成は、前記実施形態
（１）と同じである。[Embodiment (2)] Next, FIGS.
An embodiment (2) of the present invention will be described based on FIG. In the embodiment (2), the air-fuel ratio sensors 23 and 27 are provided on both the upstream side and the downstream side of the catalyst 22. The upstream air-fuel ratio sensor (hereinafter, referred to as “upstream sensor”) 23 is a linear A / F sensor that outputs a linear air-fuel ratio signal according to the air-fuel ratio of the exhaust gas, as in the first embodiment. As the downstream air-fuel ratio sensor (hereinafter, referred to as “downstream sensor”) 27, an oxygen sensor or the like whose output voltage is inverted according to rich / lean air-fuel ratio of exhaust gas is used. Needless to say, the downstream sensor 27 may be a linear A / F sensor or the like, like the upstream sensor 23. The other system configuration is the same as that of the embodiment (1).
【００４４】ＥＣＵ２６は、図８の目標φ算出プログラ
ムで算出した目標燃料過剰率φrefと実際の燃料過剰率
φとの偏差を小さくするように燃料噴射量をフィードバ
ック補正して、触媒内状態量ＯＳを目標触媒内状態量Ｏ
Ｓref 付近に制御する。The ECU 26 performs feedback correction of the fuel injection amount so as to reduce the deviation between the target excess fuel ratio φref calculated by the target φ calculation program of FIG. Is the target state quantity O in the catalyst.
Control near Sref.
【００４５】図８の目標φ算出プログラムは、所定クラ
ンク角毎又は所定時間毎に起動され、まず、ステップ２
０１で、上流側センサ２３の出力（触媒２２に流入する
排出ガスの空燃比）がリッチかリーンかを判別する。The target φ calculation program of FIG. 8 is started at every predetermined crank angle or every predetermined time.
At 01, it is determined whether the output of the upstream sensor 23 (the air-fuel ratio of the exhaust gas flowing into the catalyst 22) is rich or lean.
【００４６】もし、上流側センサ２３の出力がリッチと
判定されれば、ステップ２０２に進み、前回演算時から
今回演算時までの触媒内状態量の変化量ΔＯＳ(i) を次
式により算出する。 ΔＯＳ(i) ＝ｋｒ×（φ−φref ）×Ｑ(i-d) ｋｒ：重み係数 φ：上流側センサ２３で検出した実際の燃料過剰率 φref ：目標燃料過剰率 Ｑ(i-d) ：現時点ｉよりも遅れ時間ｄ前の過去の空気量If the output of the upstream sensor 23 is determined to be rich, the routine proceeds to step 202, where the change amount ΔOS (i) of the state quantity in the catalyst from the previous calculation to the current calculation is calculated by the following equation. . ΔOS (i) = kr × (φ−φref) × Q (id) kr: weighting factor φ: actual excess fuel ratio detected by the upstream sensor 23 φref: target excess fuel ratio Q (id): more than the current i Past air volume before delay time d
【００４７】ここで、重み係数ｋｒは、実際の触媒内状
態量の代用情報となる下流側センサ２７の出力（触媒２
２から流出する排出ガスの空燃比）に応じて次のように
設定される。Here, the weighting coefficient kr is the output of the downstream sensor 27 (catalyst 2
2 is set as follows according to the air-fuel ratio of the exhaust gas flowing out of the fuel cell 2).
【００４８】下流側センサ２７の出力（実際の触媒内
状態量）がリッチの時は、重み係数ｋｒを１よりも小さ
い所定値に設定する。この所定値は、予め設定した固定
値でも良いが、下流側センサ２７の出力に応じてマップ
又は数式により設定しても良い。When the output of the downstream sensor 27 (actual in-catalyst state quantity) is rich, the weight coefficient kr is set to a predetermined value smaller than 1. The predetermined value may be a fixed value set in advance, or may be set by a map or a mathematical expression according to the output of the downstream sensor 27.
【００４９】下流側センサ２７の出力（実際の触媒内
状態量）がリーンの時は、重み係数ｋｒを１よりも大き
い所定値に設定する。この所定値は、予め設定した固定
値でも良いが、下流側センサ２７の出力に応じてマップ
又は数式により設定しても良い。When the output (actual in-catalyst state quantity) of the downstream sensor 27 is lean, the weight coefficient kr is set to a predetermined value larger than 1. The predetermined value may be a fixed value set in advance, or may be set by a map or a mathematical expression according to the output of the downstream sensor 27.
【００５０】下流側センサ２７の出力（実際の触媒内
状態量）がストイキの時は、重み係数ｋｒを１に設定す
る。尚、ｋｒ＝１とする下流側センサ２７の出力の範囲
をある程度幅を持たせて、下流側センサ２７の出力（実
際の触媒内状態量）がストイキに近ければ、ｋｒ＝１と
しても良い。When the output (actual in-catalyst state quantity) of the downstream sensor 27 is stoichiometric, the weight coefficient kr is set to one. It should be noted that the output range of the downstream sensor 27 where kr = 1 has a certain range, and if the output (actual in-catalyst state quantity) of the downstream sensor 27 is close to stoichiometry, kr = 1 may be set.
【００５１】一方、上記ステップ２０１で、上流側セン
サ２３の出力がリーンと判定されれば、ステップ２０２
に進み、重み係数ｋｌを用いて、前回演算時から今回演
算時までの触媒内状態量の変化量ΔＯＳ(i) を次式によ
り算出する。 ΔＯＳ(i) ＝ｋｌ×（φ−φref ）×Ｑ(i-d)On the other hand, if it is determined in step 201 that the output of the upstream sensor 23 is lean, step 202
Then, using the weighting coefficient kl, the change amount ΔOS (i) of the in-catalyst state quantity from the previous calculation to the current calculation is calculated by the following equation. ΔOS (i) = kl × (φ−φref) × Q (id)
【００５２】ここで、重み係数ｋｌは、実際の触媒内状
態量の代用情報となる下流側センサ２７の出力（触媒２
２から流出する排出ガスの空燃比）に応じて次のように
設定される。Here, the weighting factor kl is determined by the output of the downstream sensor 27 (catalyst 2
2 is set as follows according to the air-fuel ratio of the exhaust gas flowing out of the fuel cell 2).
【００５３】下流側センサ２７の出力（実際の触媒内
状態量）がリッチの時は、重み係数ｋｌを１よりも大き
い所定値に設定する。この所定値は、予め設定した固定
値でも良いが、下流側センサ２７の出力に応じてマップ
又は数式により設定しても良い。When the output (actual in-catalyst state quantity) of the downstream sensor 27 is rich, the weight coefficient kl is set to a predetermined value larger than 1. The predetermined value may be a fixed value set in advance, or may be set by a map or a mathematical expression according to the output of the downstream sensor 27.
【００５４】下流側センサ２７の出力（実際の触媒内
状態量）がリーンの時は、重み係数ｋｌを１よりも小さ
い所定値に設定する。この所定値は、予め設定した固定
値でも良いが、下流側センサ２７の出力に応じてマップ
又は数式により設定しても良い。When the output of the downstream sensor 27 (actual in-catalyst state quantity) is lean, the weight coefficient kl is set to a predetermined value smaller than 1. The predetermined value may be a fixed value set in advance, or may be set by a map or a mathematical expression according to the output of the downstream sensor 27.
【００５５】下流側センサ２７の出力（実際の触媒内
状態量）がストイキの時は、重み係数ｋｌを１に設定す
る。尚、ｋｌ＝１とする下流側センサ２７の出力の範囲
をある程度幅を持たせて、下流側センサ２７の出力（実
際の触媒内状態量）がストイキに近ければ、ｋｌ＝１と
しても良い。When the output (actual in-catalyst state quantity) of the downstream sensor 27 is stoichiometric, the weight coefficient kl is set to 1. Note that the output range of the downstream sensor 27 where kl = 1 is set to have a certain width, and if the output (actual in-catalyst state quantity) of the downstream sensor 27 is close to stoichiometry, kl = 1 may be set.
【００５６】上記ステップ２０２，２０３で、下流側セ
ンサ２７の出力に応じて触媒内状態量の変化量ΔＯＳ
(i) の演算式のパラメータ（重み係数ｋｒ，ｋｌ）を可
変する処理が特許請求の範囲でいうパラメータ可変手段
としての役割を果たす。また、上記ステップ２０２，２
０３で、パラメータ（重み係数ｋｒ，ｋｌ）を用いて、
触媒内状態量の変化量ΔＯＳ(i) を補正しながら求める
処理が特許請求の範囲でいう補正手段としての役割を果
たす。In the above steps 202 and 203, the variation ΔOS of the state quantity in the catalyst in accordance with the output of the downstream side sensor 27
The process of varying the parameters (weighting factors kr, kl) of the operation formula (i) serves as a parameter varying means in the claims. Steps 202 and 2 above
03, using the parameters (weight coefficients kr, kl),
The process of obtaining the change amount ΔOS (i) of the state amount in the catalyst while correcting the change amount serves as a correction means in the claims.
【００５７】以上のようにしてステップ２０２又は２０
３で、触媒内状態量の変化量ΔＯＳ(i) を算出した後、
ステップ２０４に進み、触媒内状態量の変化量ΔＯＳ
(i) を前回の触媒内状態量算出値ＯＳ(i-1) に積算して
現在の触媒内状態量ＯＳ(i) を求める。 ＯＳ(i) ＝ΔＯＳ(i) ＋ＯＳ(i-1)As described above, step 202 or 20
In step 3, after calculating the variation ΔOS (i) of the state quantity in the catalyst,
Proceeding to step 204, the change amount ΔOS of the state quantity in the catalyst
(i) is added to the previous in-catalyst state quantity calculation value OS (i-1) to obtain the current in-catalyst state quantity OS (i). OS (i) = ΔOS (i) + OS (i-1)
【００５８】その後、ステップ２０５に進み、触媒内状
態量ＯＳ(i) の算出値を触媒２２のリーン側／リッチ側
飽和吸着量に相当するガード値ＯＳmin ，ＯＳmax でガ
ード処理する。Thereafter, the routine proceeds to step 205, where the calculated value of the in-catalyst state quantity OS (i) is subjected to guard processing with guard values OSmin and OSmax corresponding to the lean / rich side saturated adsorption amount of the catalyst 22.
【００５９】この後、ステップ２０６に進み、目標触媒
内状態量ＯＳref と現在の触媒内状態量ＯＳ(i) との偏
差ＯＳerror を算出する。 ＯＳerror ＝ＯＳref −ＯＳ(i)Thereafter, the routine proceeds to step 206, where a deviation OSerror between the target in-catalyst state quantity OSref and the current in-catalyst state quantity OS (i) is calculated. OSerror = OSref-OS (i)
【００６０】そして、次のステップ２０７で、ＰＩＤコ
ントローラの比例ゲイン、積分ゲイン、微分ゲインをマ
ップ等により算出した後、ステップ２０８に進み、各ゲ
インを用いて、ＰＩＤコントローラの制御パラメータＡ
１，Ａ２，Ｂ１，Ｂ２，Ｂ３を前記実施形態（１）と同
様の方法で算出する。Then, in the next step 207, the proportional gain, the integral gain, and the differential gain of the PID controller are calculated by using a map or the like, and the process proceeds to step 208, where the control parameter A of the PID controller is calculated using each gain.
1, A2, B1, B2, and B3 are calculated in the same manner as in the embodiment (1).
【００６１】この後、ステップ２０９に進み、上記制御
パラメータＡ１，Ａ２，Ｂ１，Ｂ２，Ｂ３と過去の目標
燃料過剰率φref を用いて目標燃料過剰率補正量Δφre
fBを次式により算出する。 ΔφrefB＝Ｂ１・ＯＳerror(i)−Ｂ２・ＯＳerror(i-1)
＋Ｂ３・ＯＳerror(i-2)＋Ａ１・φref (i-1) −Ａ２・
φref (i-2)Thereafter, the routine proceeds to step 209, where the target fuel excess ratio correction amount Δφre is calculated using the control parameters A1, A2, B1, B2, B3 and the past target fuel excess ratio φref.
fB is calculated by the following equation. ΔφrefB = B1 · OSerror (i) −B2 · OSerror (i−1)
+ B3 · OSerror (i-2) + A1 · φref (i-1) -A2 ·
φref (i-2)
【００６２】そして、次のステップ２１０で、後述する
図９のΔφrefA算出プログラムを実行して、サブフィー
ドバックによる目標燃料過剰率補正量ΔφrefAを算出す
る。この後、ステップ２１１に進み、上記ステップ２０
９，２１０で算出した２つの目標燃料過剰率補正量Δφ
refB，ΔφrefAをベース値“１”に加算して、触媒２２
上流側の目標燃料過剰率φref を設定し、本プログラム
を終了する。 φref ＝１＋ΔφrefA＋ΔφrefBThen, in the next step 210, a ΔφrefA calculation program shown in FIG. 9 to be described later is executed to calculate a target excess fuel ratio correction amount ΔφrefA by sub-feedback. Thereafter, the process proceeds to step 211, and the process proceeds to step 20.
The two target excess fuel ratio correction amounts Δφ calculated in 9, 210
refB and ΔφrefA are added to the base value “1”, and the catalyst 22
The target excess fuel ratio φref on the upstream side is set, and the program ends. φref = 1 + ΔφrefA + ΔφrefB
【００６３】一方、上記ステップ２１０で、図９のΔφ
refA算出プログラムが起動されると、まず、ステップ３
０１で、目標触媒内状態量ＯＳref と現在の触媒内状態
量ＯＳ(i) との偏差ＯＳerror(i)に応じて、サブフィー
ドバックの制御パラメータｋｉ，ｋｐを次式により算出
する。 ｋｉ＝ｋｉｓ×ＯＳerror(i) ｋｐ＝ｋｐｓ×ＯＳerror(i) ここで、ｋｉｓとｋｐｓは、それぞれ制御パラメータｋ
ｉ，ｋｐのベース値である。On the other hand, in step 210, Δφ in FIG.
When the refA calculation program is started, first, step 3
At 01, the control parameters ki and kp of the sub-feedback are calculated according to the following equation according to the deviation OSerror (i) between the target in-catalyst state quantity OSref and the current in-catalyst state quantity OS (i). ki = kis × OSerror (i) kp = kps × OSerror (i) where kis and kps are control parameters k
Base values of i and kp.
【００６４】この後、ステップ３０２に進み、現在の下
流側センサ２７の出力（実際の触媒内状態量）がリッチ
かリーンかを判別する。もし、下流側センサ２７の出力
がリッチと判定されれば、ステップ３０３に進み、前回
もリッチであったか否かを判定する。前回も今回もリッ
チである場合には、ステップ３０４に進み、前回の目標
燃料過剰率補正量ΔφrefA(i-1) に制御パラメータｋｉ
を加算して今回の目標燃料過剰率補正量ΔφrefA(i) を
求める。 ΔφrefA(i) ＝ΔφrefA(i-1) ＋ｋｉThereafter, the routine proceeds to step 302, where it is determined whether the current output (actual in-catalyst state quantity) of the downstream sensor 27 is rich or lean. If the output of the downstream sensor 27 is determined to be rich, the process proceeds to step 303, and it is determined whether or not the previous time was rich. If the previous time and this time are rich, the process proceeds to step 304, and the control parameter ki is added to the previous target excess fuel ratio correction amount ΔφrefA (i-1).
Is added to obtain the current target excess fuel ratio correction amount ΔφrefA (i). ΔφrefA (i) = ΔφrefA (i-1) + ki
【００６５】また、下流側センサ２７の出力が前回はリ
ーン側で今回リッチに反転した場合は、ステップ３０５
に進み、前回の目標燃料過剰率補正量ΔφrefA(i-1) に
制御パラメータｋｐを加算して今回の目標燃料過剰率補
正量ΔφrefA(i) を求める。 ΔφrefA(i) ＝ΔφrefA(i-1) ＋ｋｐIf the output of the downstream sensor 27 has been inverted to rich this time on the lean side last time, step 305
Then, the control parameter kp is added to the previous target excess fuel ratio correction amount ΔφrefA (i-1) to obtain the current target excess fuel ratio correction amount ΔφrefA (i). ΔφrefA (i) = ΔφrefA (i-1) + kp
【００６６】一方、ステップ３０２で、現在の下流側セ
ンサ２７の出力（実際の触媒内状態量）がリーンと判定
されれた場合は、ステップ３０６に進み、前回もリーン
であったか否かを判定する。前回も今回もリーンである
場合には、ステップ３０８に進み、前回の目標燃料過剰
率補正量ΔφrefA(i-1) に制御パラメータｋｉを加算し
て今回の目標燃料過剰率補正量ΔφrefA(i) を求める。 ΔφrefA(i) ＝ΔφrefA(i-1) ＋ｋｉOn the other hand, if it is determined in step 302 that the current output (actual in-catalyst state amount) of the downstream sensor 27 is lean, the process proceeds to step 306 to determine whether the previous time was also lean. . If both the previous time and this time are lean, the process proceeds to step 308, where the control parameter ki is added to the previous target excess fuel ratio correction amount ΔφrefA (i-1), and the current target excess fuel ratio correction amount ΔφrefA (i) Ask for. ΔφrefA (i) = ΔφrefA (i-1) + ki
【００６７】また、下流側センサ２７の出力が前回はリ
ッチ側で今回リーンに反転した場合は、ステップ３０７
に進み、前回の目標燃料過剰率補正量ΔφrefA(i-1) に
制御パラメータｋｐを加算して今回の目標燃料過剰率補
正量ΔφrefA(i) を求める。 ΔφrefA(i) ＝ΔφrefA(i-1) ＋ｋｐIf the output of the downstream sensor 27 has been inverted to rich this time and lean this time, then step 307
Then, the control parameter kp is added to the previous target excess fuel ratio correction amount ΔφrefA (i-1) to obtain the current target excess fuel ratio correction amount ΔφrefA (i). ΔφrefA (i) = ΔφrefA (i-1) + kp
【００６８】以上のようにして、ステップ３０４，３０
５，３０７，３０８のいずれかで、目標燃料過剰率補正
量ΔφrefA(i) を算出した後、ステップ３０９に進み、
目標燃料過剰率補正量ΔφrefA(i) を適正なガード値で
ガード処理して、本プログラムを終了する。As described above, steps 304 and 30
After calculating the target fuel excess ratio correction amount ΔφrefA (i) in any one of 5, 307 and 308, the routine proceeds to step 309,
The target excess fuel ratio correction amount ΔφrefA (i) is subjected to guard processing with an appropriate guard value, and the program ends.
【００６９】以上説明した実施形態（２）の過渡時の制
御特性を図１０のタイムチャートを用いて説明する。図
１０のタイムチャートは、実施形態（２）の制御特性を
実施形態（１）の制御特性と比較して示している。The control characteristics during the transition of the embodiment (2) described above will be described with reference to the time chart of FIG. The time chart of FIG. 10 shows the control characteristics of the embodiment (2) in comparison with the control characteristics of the embodiment (1).
【００７０】実施形態（２）では、触媒２２の下流側に
設置した下流側センサ２７の出力（触媒２２から流出す
る排出ガスの空燃比）が実際の触媒内状態量に追従して
変化する点に着目し、触媒内状態量の変化量ΔＯＳ(i)
の演算式のパラメータ（重み係数ｋｒ，ｋｌ）を下流側
センサ２７の出力（実際の触媒内状態量）に応じて可変
するようにしたので、触媒内状態量ＯＳ(i) の算出値を
下流側センサ２７の出力（実際の触媒内状態量）に応じ
て逐次補正することができる。これにより、実施形態
（２）では、触媒内状態量ＯＳ(i) の算出誤差（推定誤
差）を実施形態（１）よりも少なくすることができ、実
際の触媒内状態量に追従した応答性の良い空燃比制御を
実施することができる。これにより、過渡時に触媒２２
上流側の燃料過剰率φや、下流側センサ２７の出力（実
際の触媒内状態量）を早期にストイキに収束させること
ができ、過渡時でも安定した排出ガス浄化性能を維持す
ることができる。In the embodiment (2), the point at which the output of the downstream sensor 27 (the air-fuel ratio of the exhaust gas flowing out of the catalyst 22) installed downstream of the catalyst 22 changes following the actual state quantity in the catalyst. And the change amount ΔOS (i) of the state quantity in the catalyst.
(Weighting coefficients kr, kl) are varied according to the output of the downstream sensor 27 (actual in-catalyst state quantity), so that the calculated value of the in-catalyst state quantity OS (i) is The correction can be made sequentially according to the output of the side sensor 27 (actual in-catalyst state quantity). As a result, in the embodiment (2), the calculation error (estimation error) of the in-catalyst state quantity OS (i) can be made smaller than that in the embodiment (1), and the responsiveness following the actual in-catalyst state quantity is improved. A good air-fuel ratio control can be implemented. This allows the catalyst 22 to be
The excess fuel ratio φ on the upstream side and the output of the downstream sensor 27 (actual in-catalyst state quantity) can be quickly converged to stoichiometry, and stable exhaust gas purification performance can be maintained even during a transition.
【００７１】しかも、本実施形態（２）では、触媒２２
の下流側の空燃比（下流側センサ２７の出力）を目標燃
料過剰率φref （目標触媒内状態量ＯＳref ）に反映さ
せるサブフィードバックの制御パラメータｋｉ，ｋｐ
を、下流側センサ２７の出力（実際の触媒内状態量）に
応じて可変するようにしたので、下流側センサ２７の出
力（実際の触媒内状態量）に応じて目標燃料過剰率φre
f （目標触媒内状態量ＯＳref ）を応答性良く可変する
ことができる。Further, in the embodiment (2), the catalyst 22
The sub-feedback control parameters ki and kp that reflect the air-fuel ratio on the downstream side (output of the downstream sensor 27) to the target excess fuel ratio φref (target state quantity OSref).
Is varied according to the output of the downstream sensor 27 (actual in-catalyst state quantity), so that the target excess fuel ratio φre is determined in accordance with the output of the downstream sensor 27 (actual in-catalyst state quantity).
f (the target in-catalyst state quantity OSref) can be varied with good responsiveness.
【図１】本発明の実施形態（１）を示すエンジン制御シ
ステム全体の概略構成図FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment (1) of the present invention.
【図２】実施形態（１）の目標φ算出プログラムの処理
の流れを示すフローチャート（その１）FIG. 2 is a flowchart showing a processing flow of a target φ calculation program according to the embodiment (1) (part 1);
【図３】実施形態（１）の目標φ算出プログラムの処理
の流れを示すフローチャート（その２）FIG. 3 is a flowchart showing a processing flow of a target φ calculation program according to the embodiment (1) (part 2);
【図４】触媒内状態量ＯＳの算出値に対するガード値Ｏ
Ｓmin ，ＯＳmax と空気量Ｑとの関係を示す図FIG. 4 shows a guard value O with respect to a calculated value of a state quantity OS in a catalyst.
Diagram showing the relationship between Smin, OSmax and air volume Q
【図５】過渡運転時の燃料過剰率φと触媒内状態量ＯＳ
の挙動の一例を示すタイムチャートFIG. 5 shows the excess fuel ratio φ and the state quantity OS in the catalyst during the transient operation.
Time chart showing an example of the behavior of
【図６】近似微分を用いて制御パラメータＡ１，Ａ２，
Ｂ１，Ｂ２，Ｂ３を算出する方法を説明するフローチャ
ートFIG. 6 shows control parameters A1, A2, and
Flowchart for explaining a method of calculating B1, B2, and B3
【図７】本発明の実施形態（２）を示すエンジン制御シ
ステム全体の概略構成図FIG. 7 is a schematic configuration diagram of an entire engine control system showing an embodiment (2) of the present invention.
【図８】実施形態（２）の目標φ算出プログラムの処理
の流れを示すフローチャートFIG. 8 is a flowchart showing a processing flow of a target φ calculation program according to the embodiment (2).
【図９】ΔφrefA算出プログラムの処理の流れを示すフ
ローチャートFIG. 9 is a flowchart showing the flow of processing of a ΔφrefA calculation program.
【図１０】実施形態（２）の制御特性を実施形態（１）
の制御特性と比較して示すタイムチャートFIG. 10 shows the control characteristics of the embodiment (2) according to the embodiment (1).
Time chart showing comparison with control characteristics of
１１…エンジン（内燃機関）、１２…吸気管、１４…エ
アフローメータ（空気量検出手段）、２０…燃料噴射
弁、２１…排気管、２２…触媒、２３…空燃比センサ
（空燃比検出手段，上流側センサ）、２６…ＥＣＵ（触
媒内状態量算出手段，噴射制御手段，ガード処理手段，
補正手段，パラメータ可変手段）、２７…空燃比センサ
（下流側センサ）。DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter (air amount detection means), 20 ... Fuel injection valve, 21 ... Exhaust pipe, 22 ... Catalyst, 23 ... Air-fuel ratio sensor (Air-fuel ratio detection means, ECU (upstream sensor), 26 ... ECU (in-catalyst state quantity calculating means, injection control means, guard processing means,
Correction means, parameter variable means), 27 ... air-fuel ratio sensor (downstream sensor).
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｆ０２Ｄ 45/00 ３２４ Ｆ０２Ｄ 45/00 ３２４ ３６８ ３６８Ｇ (72)発明者 山下 幸宏 愛知県刈谷市昭和町１丁目１番地 株式会 社デンソー内 Ｆターム(参考） 3G084 BA05 BA09 BA13 EA07 EB13 FA07 FA10 FA11 FA29 FA30 FA33 FA38 3G091 AA17 AA23 AA28 AB03 BA14 BA15 BA19 CB02 DA01 DA02 DA10 DB02 DB04 DB05 DB06 DB07 DB10 DC01 DC03 EA01 EA05 EA06 EA07 EA16 EA31 EA34 FB10 FB12 HA36 HA37 HA42 3G301 HA01 JA25 JA26 JA27 LB01 MA11 NA03 NA04 NC01 NC02 ND01 PA01A PA07A PA11A PD01A PE01A PE03A PE08A──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification code FI Theme coat ゛ (Reference) F02D 45/00 324 F02D 45/00 324 368 368G (72) Inventor Yukihiro Yamashita 1-chome, Showa-cho, Kariya city, Aichi prefecture No. 1 F-term in Denso Co., Ltd. (Reference) 3G084 BA05 BA09 BA13 EA07 EB13 FA07 FA10 FA11 FA29 FA30 FA33 FA38 3G091 AA17 AA23 AA28 AB03 BA14 BA15 BA19 CB02 DA01 DA02 DA10 DB02 DB04 DB05 DB06 DB07 DB10 EA06 EA01 EA31 EA34 FB10 FB12 HA36 HA37 HA42 3G301 HA01 JA25 JA26 JA27 LB01 MA11 NA03 NA04 NC01 NC02 ND01 PA01A PA07A PA11A PD01A PE01A PE03A PE08A
Claims (12)
関において、 前記触媒の上流又は下流の排出ガスの空燃比を検出する
空燃比検出手段と、 内燃機関に吸入される空気量を検出する空気量検出手段
と、 前記空燃比検出手段で検出した排出ガスの空燃比と前記
空気量検出手段で検出した空気量とに基づいて触媒内状
態量を算出する触媒内状態量算出手段と、 前記触媒内状態量と目標値との偏差が小さくなるように
燃料噴射量を補正する噴射制御手段とを備えていること
を特徴とする内燃機関の空燃比制御装置。1. An internal combustion engine provided with a catalyst for purifying exhaust gas, wherein an air-fuel ratio detecting means for detecting an air-fuel ratio of exhaust gas upstream or downstream of the catalyst, and an amount of air taken into the internal combustion engine is detected. Air amount detection means; and an in-catalyst state amount calculation means for calculating an in-catalyst state amount based on an air-fuel ratio of exhaust gas detected by the air-fuel ratio detection means and an air amount detected by the air amount detection means, An air-fuel ratio control device for an internal combustion engine, comprising: injection control means for correcting a fuel injection amount so as to reduce a deviation between a state amount in a catalyst and a target value.
内状態量を算出する際に用いる空気量として、少なくと
も燃料噴射から排出ガスの空燃比を検出するまでの遅れ
時間分過去の空気量を用いることを特徴とする請求項１
に記載の内燃機関の空燃比制御装置。2. The in-catalyst state quantity calculating means includes, as an air amount used in calculating the in-catalyst state quantity, at least a delay time from fuel injection to detection of an air-fuel ratio of exhaust gas. 2. The method according to claim 1, wherein
3. The air-fuel ratio control device for an internal combustion engine according to claim 1.
算周期で目標空燃比に対する前記排出ガスの空燃比のず
れ量と前記空気量とに基づいて触媒内状態量の変化量を
算出し、この変化量を積算して現在の触媒内状態量を求
めることを特徴とする請求項１又は２に記載の内燃機関
の空燃比制御装置。3. The in-catalyst state quantity calculating means calculates a change amount of the in-catalyst state quantity based on a deviation amount of the air-fuel ratio of the exhaust gas with respect to a target air-fuel ratio and the air amount in a predetermined calculation cycle. 3. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the amount of change is integrated to obtain a current state amount in the catalyst.
飽和吸着量に相当するガード値で制限するガード処理手
段を備えていることを特徴とする請求項１乃至３のいず
れかに記載の内燃機関の空燃比制御装置。4. The apparatus according to claim 1, further comprising a guard processing means for limiting a calculated value of the state quantity in the catalyst by a guard value corresponding to a saturated adsorption amount of the catalyst. Air-fuel ratio control device for an internal combustion engine.
前記空気量に応じて変化させることを特徴とする請求項
４に記載の内燃機関の空燃比制御装置。5. The air-fuel ratio control device for an internal combustion engine according to claim 4, wherein said guard processing means changes said guard value in accordance with said air amount.
関において、 前記触媒の上流又は下流の排出ガスのガス濃度を検出す
るガス濃度検出手段と、 内燃機関に吸入される空気量を検出する空気量検出手段
と、 前記ガス濃度検出手段で検出した排出ガスのガス濃度と
前記空気量検出手段で検出した空気量とに基づいて触媒
内状態量を算出する触媒内状態量算出手段と、 前記触媒内状態量と目標値との偏差が小さくなるように
燃料噴射量を補正する噴射制御手段とを備えていること
を特徴とする内燃機関の空燃比制御装置。6. An internal combustion engine provided with a catalyst for purifying exhaust gas, a gas concentration detecting means for detecting a gas concentration of exhaust gas upstream or downstream of the catalyst, and detecting an amount of air taken into the internal combustion engine. An air amount detection unit; an in-catalyst state amount calculation unit that calculates an in-catalyst state amount based on the gas concentration of the exhaust gas detected by the gas concentration detection unit and the air amount detected by the air amount detection unit; An air-fuel ratio control device for an internal combustion engine, comprising: injection control means for correcting a fuel injection amount so as to reduce a deviation between a state amount in a catalyst and a target value.
内状態量を算出する際に、その算出値を実際の触媒内状
態量に応じて補正する補正手段を備えていることを特徴
とする請求項１乃至６のいずれかに記載の内燃機関の空
燃比制御装置。7. The in-catalyst state quantity calculating means includes a correcting means for correcting the calculated value in accordance with an actual in-catalyst state quantity when calculating the in-catalyst state quantity. The air-fuel ratio control device for an internal combustion engine according to any one of claims 1 to 6.
情報を、前記触媒から流出する排出ガスの空燃比又はガ
ス濃度を検出する触媒下流側のセンサの出力から得るこ
とを特徴とする請求項７に記載の内燃機関の空燃比制御
装置。8. The apparatus according to claim 1, wherein the correction means obtains information on the actual state quantity in the catalyst from an output of a sensor on the downstream side of the catalyst which detects an air-fuel ratio or a gas concentration of exhaust gas flowing out of the catalyst. An air-fuel ratio control device for an internal combustion engine according to claim 7.
手段により算出した触媒内状態量と実際の触媒内状態量
との偏差に応じて前記触媒内状態量の目標値を制御する
パラメータを可変するパラメータ可変手段を備えている
ことを特徴とする請求項７又は８に記載の内燃機関の空
燃比制御装置。9. The correction means includes a parameter for controlling a target value of the in-catalyst state quantity according to a deviation between the in-catalyst state quantity calculated by the in-catalyst state quantity calculation means and an actual in-catalyst state quantity. 9. The air-fuel ratio control device for an internal combustion engine according to claim 7, further comprising a variable parameter changing means.
内状態量の目標値を制御するパラメータとして、触媒内
状態量を算出する式のパラメータを可変することを特徴
とする請求項９に記載の内燃機関の空燃比制御装置。10. The internal combustion engine according to claim 9, wherein the parameter varying unit varies a parameter of an equation for calculating a state quantity in the catalyst as a parameter for controlling a target value of the state quantity in the catalyst. Engine air-fuel ratio control device.
内状態量の目標値を制御するパラメータとして、前記触
媒の下流側の空燃比を前記目標値に反映させるサブフィ
ードバックの制御パラメータを可変することを特徴とす
る請求項９に記載の内燃機関の空燃比制御装置。11. The parameter varying means may vary a sub-feedback control parameter for reflecting a downstream air-fuel ratio of the catalyst to the target value as a parameter for controlling a target value of the in-catalyst state quantity. The air-fuel ratio control device for an internal combustion engine according to claim 9, wherein:
内状態量算出手段により算出した触媒内状態量と実際の
触媒内状態量との偏差が所定値以下の場合に該偏差を０
と見なすことを特徴とする請求項９乃至１１のいずれか
に記載の内燃機関の空燃比制御装置。12. The parameter changing means sets the deviation to 0 when the deviation between the in-catalyst state quantity calculated by the in-catalyst state quantity calculation means and the actual in-catalyst state quantity is equal to or less than a predetermined value.
The air-fuel ratio control device for an internal combustion engine according to any one of claims 9 to 11, wherein:
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000303146A JP4636214B2 (en) | 2000-06-20 | 2000-10-03 | Air-fuel ratio control device for internal combustion engine |
| US09/866,804 US20020011067A1 (en) | 2000-06-20 | 2001-05-30 | Air-fuel ratio control system for engine with in-catalyst state compensation |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000-189733 | 2000-06-20 | ||
| JP2000189733 | 2000-06-20 | ||
| JP2000303146A JP4636214B2 (en) | 2000-06-20 | 2000-10-03 | Air-fuel ratio control device for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002081339A true JP2002081339A (en) | 2002-03-22 |
| JP4636214B2 JP4636214B2 (en) | 2011-02-23 |
Family
ID=26594564
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000303146A Expired - Fee Related JP4636214B2 (en) | 2000-06-20 | 2000-10-03 | Air-fuel ratio control device for internal combustion engine |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US20020011067A1 (en) |
| JP (1) | JP4636214B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100747909B1 (en) * | 2006-07-10 | 2007-08-08 | 현대자동차주식회사 | The air-bag housing structure of a passenger seat |
| US7559193B2 (en) | 2005-11-01 | 2009-07-14 | Hitachi, Ltd. | Control apparatus and method for internal combustion engine |
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|---|---|---|---|---|
| JPH06249032A (en) * | 1993-03-02 | 1994-09-06 | Toyota Motor Corp | Air-fuel ratio control device of internal combustion engine |
| JPH0763111A (en) * | 1993-08-20 | 1995-03-07 | Mitsubishi Motors Corp | Misfire detection device for engine |
| JPH09310636A (en) * | 1996-05-20 | 1997-12-02 | Unisia Jecs Corp | Air-fuel ratio controller for internal combustion engine |
| JPH09310635A (en) * | 1996-05-20 | 1997-12-02 | Toyota Motor Corp | Air-fuel ratio control device of internal combustion engine |
| JP2000008921A (en) * | 1998-06-17 | 2000-01-11 | Unisia Jecs Corp | Oxygen storage quantity control device for three-way catalyst |
-
2000
- 2000-10-03 JP JP2000303146A patent/JP4636214B2/en not_active Expired - Fee Related
-
2001
- 2001-05-30 US US09/866,804 patent/US20020011067A1/en not_active Abandoned
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06249032A (en) * | 1993-03-02 | 1994-09-06 | Toyota Motor Corp | Air-fuel ratio control device of internal combustion engine |
| JPH0763111A (en) * | 1993-08-20 | 1995-03-07 | Mitsubishi Motors Corp | Misfire detection device for engine |
| JPH09310636A (en) * | 1996-05-20 | 1997-12-02 | Unisia Jecs Corp | Air-fuel ratio controller for internal combustion engine |
| JPH09310635A (en) * | 1996-05-20 | 1997-12-02 | Toyota Motor Corp | Air-fuel ratio control device of internal combustion engine |
| JP2000008921A (en) * | 1998-06-17 | 2000-01-11 | Unisia Jecs Corp | Oxygen storage quantity control device for three-way catalyst |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7559193B2 (en) | 2005-11-01 | 2009-07-14 | Hitachi, Ltd. | Control apparatus and method for internal combustion engine |
| DE102006051465B4 (en) * | 2005-11-01 | 2012-11-22 | Hitachi, Ltd. | Method and device for controlling an internal combustion engine |
| KR100747909B1 (en) * | 2006-07-10 | 2007-08-08 | 현대자동차주식회사 | The air-bag housing structure of a passenger seat |
Also Published As
| Publication number | Publication date |
|---|---|
| US20020011067A1 (en) | 2002-01-31 |
| JP4636214B2 (en) | 2011-02-23 |
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