JP2003097341A - Exhaust control device of internal combustion engine - Google Patents
Exhaust control device of internal combustion engineInfo
- Publication number
- JP2003097341A JP2003097341A JP2002219469A JP2002219469A JP2003097341A JP 2003097341 A JP2003097341 A JP 2003097341A JP 2002219469 A JP2002219469 A JP 2002219469A JP 2002219469 A JP2002219469 A JP 2002219469A JP 2003097341 A JP2003097341 A JP 2003097341A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- exhaust gas
- exhaust
- purification device
- detection
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Landscapes
- 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]
【産業上の利用分野】本発明は、排気ガス中の特定成分
例えば、酸素濃度等を測定し空燃比を調整したり触媒等
排気浄化装置の診断を行う装置に関し、特に、排気系の
リークを検出し、リークによる有害排気ガスの増加や誤
診断等を防止するのに好適な内燃機関の排気ガス制御装
置。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring a specific component in exhaust gas, such as oxygen concentration, for adjusting the air-fuel ratio and for diagnosing an exhaust purification device such as a catalyst, and more particularly, for detecting a leak in an exhaust system. An exhaust gas control device for an internal combustion engine, which is suitable for detecting and preventing an increase in harmful exhaust gas due to a leak, a misdiagnosis, and the like.
【０００２】[0002]
【従来の技術】従来より、排気ガス中の酸素濃度を測定
し空燃比をフィードバック制御する装置が知られてい
る。特に、空燃比を理論空燃比に調整し、かつ排気系に
三元触媒を設けることにより有害排気ガスであるＨＣ、
ＣＯやＮＯｘを浄化する排気浄化装置は自動車の排気ガ
ス浄化装置として広く普及している。2. Description of the Related Art Conventionally, there is known a device for measuring oxygen concentration in exhaust gas and performing feedback control of air-fuel ratio. In particular, by adjusting the air-fuel ratio to the theoretical air-fuel ratio and providing a three-way catalyst in the exhaust system, HC which is harmful exhaust gas,
Exhaust gas purification devices that purify CO and NOx are widely used as exhaust gas purification devices for automobiles.
【０００３】また、排気浄化装置の構成部品である三元
触媒や酸素濃度センサが劣化または故障した場合に有害
排気ガスが大気に放出されてしまうため、これらの部品
の劣化や故障を診断する診断装置も広く普及している。
例えば触媒の診断装置として特開平４−２９２５５４
（ＵＳＰ５２３７８１８）がある。Further, when a three-way catalyst or an oxygen concentration sensor, which is a component of the exhaust emission control device, deteriorates or fails, harmful exhaust gas is released into the atmosphere, so that a diagnosis for diagnosing the deterioration or fault of these parts is performed. Devices are also widely used.
For example, as a catalyst diagnostic device, Japanese Patent Laid-Open No. 4-292554
(USP5237818).
【０００４】[0004]
【発明が解決しようとする課題】ところで、これらの装
置では、排気系にリークが発生した場合の事を考慮して
いない。排気系にリークが発生(例えば排気管に穴が開
いたり、接合個所の締結が緩んだり)すると、例えば内
燃機関の負荷が低く回転速度が低い場合、排気ガス圧力
が脈動する際に負圧を発生する。このため大気側から排
気系に空気が吸入されてしまう。By the way, these devices do not consider the case where a leak occurs in the exhaust system. When a leak occurs in the exhaust system (for example, a hole is formed in the exhaust pipe or the joint is loosened), for example, when the load of the internal combustion engine is low and the rotation speed is low, negative pressure is generated when the exhaust gas pressure pulsates. Occur. Therefore, air is sucked into the exhaust system from the atmosphere side.
【０００５】このようにリークが発生した場合の影響
は、リークの発生個所により異なる。例えば、空燃比制
御用の酸素濃度センサと触媒の間でリークが発生した場
合、酸素濃度センサの位置では排気ガスが理論空燃比に
なるように空燃比がフィードバック制御されるが、触媒
位置においては空気が吸入されているため酸素過剰状態
となる。このため有害ガスであるＮＯｘが触媒において
転換されず大気へ放出されてしまう。また、特開平４−
２９２５５４に提案されている様に、触媒の後流にも酸
素濃度センサを配置し、触媒前後の酸素濃度センサの出
力により触媒の診断を行う場合には、触媒後流の酸素濃
度センサが常にリーン（酸素過剰）状態を示してしまう
ため、触媒の診断ができなくなったり、誤診断したりし
てしまう。The influence of the occurrence of the leak depends on the place where the leak occurs. For example, when a leak occurs between the oxygen concentration sensor for air-fuel ratio control and the catalyst, the air-fuel ratio is feedback-controlled so that the exhaust gas is at the stoichiometric air-fuel ratio at the position of the oxygen concentration sensor, but at the catalyst position. Since air is inhaled, it becomes an oxygen excess state. Therefore, NOx, which is a harmful gas, is not converted in the catalyst and is released to the atmosphere. In addition, JP-A-4-
As proposed in 292554, when an oxygen concentration sensor is arranged also in the downstream of the catalyst and the catalyst is diagnosed by the output of the oxygen concentration sensor before and after the catalyst, the oxygen concentration sensor in the downstream of the catalyst is always lean. Since the (excess oxygen) state is displayed, the catalyst cannot be diagnosed or is erroneously diagnosed.
【０００６】また、空燃比制御用の酸素濃度センサより
上流でリークが発生した場合、通常は酸素濃度センサ位
置で理論空燃比になるようリークにより吸入された酸素
に見合う量の燃料を増量するようにフィードバック制御
されるため、燃料消費量が増大してしまう。さらに酸素
濃度センサ出力が排気ガス圧力の脈動による負圧発生に
対応してリーン出力を発生するため、酸素センサの診断
で誤診断を発生したり、空燃比が通常の空燃比制御時の
変動以上に変動して、結果的に有害ガスの大気への放出
が増大してしまうことがある。When a leak occurs upstream of the oxygen concentration sensor for controlling the air-fuel ratio, it is usual to increase the amount of fuel commensurate with the oxygen sucked in by the leak so that the stoichiometric air-fuel ratio is reached at the oxygen concentration sensor position. Since the feedback control is performed, the fuel consumption increases. Furthermore, since the oxygen concentration sensor output produces a lean output in response to negative pressure generation due to pulsation of exhaust gas pressure, a false diagnosis may occur due to the oxygen sensor diagnosis, or the air-fuel ratio may exceed the fluctuation during normal air-fuel ratio control. And the emission of harmful gases to the atmosphere may increase as a result.
【０００７】さらに、リークの発生個所が触媒より上流
の場合、排気ガス圧力が正圧の時は浄化されていない排
気ガスが大気に放出されることになる。Further, when the leak occurs upstream of the catalyst, when the exhaust gas pressure is positive, unpurified exhaust gas is released to the atmosphere.
【０００８】本発明は、リークによる有害排気ガスの大
気への放出の増加や触媒等排気浄化装置の誤診断等を抑
えることができる内燃機関の排気ガス制御装置を提供す
ることを目的とする。It is an object of the present invention to provide an exhaust gas control device for an internal combustion engine, which can suppress an increase in emission of harmful exhaust gas to the atmosphere due to a leak and an erroneous diagnosis of an exhaust purification device such as a catalyst.
【０００９】[0009]
【課題を解決するための手段】上記目的を達成するため
に、リークを検出するリーク検出手段と、リークを検出
した場合に空燃比フィードバック制御や触媒等排気浄化
装置の診断を中止する中止手段または補正する補正手段
を設けた。さらに、運転者へ警告したり、リークの検出
結果を記憶するようにした。In order to achieve the above object, a leak detecting means for detecting a leak and a stopping means for stopping a diagnosis of an air-fuel ratio feedback control or an exhaust purification device such as a catalyst when a leak is detected, or A correcting means for correcting is provided. Further, the driver is warned and the leak detection result is stored.
【００１０】[0010]
【作用】上記の本発明からなる内燃機関の排気ガス制御
装置によれば、リークを検出した場合には、例えば触媒
等排気浄化装置の診断を中止し、誤診断しないようにす
る。また、酸素濃度センサによる空燃比のフィードバッ
ク制御を中止し、例えばフィードバック制御による補正
を行わない状態で空燃比制御を行うことにより、燃料消
費の増大を抑えることができる。さらに、運転者に警告
することによってディーラー等での修理を促し、有害ガ
スの大気への放出を抑えることができる。According to the exhaust gas control system for an internal combustion engine according to the present invention, when a leak is detected, the diagnosis of the exhaust purification system for a catalyst or the like is stopped so as to prevent a false diagnosis. Further, by stopping the feedback control of the air-fuel ratio by the oxygen concentration sensor and performing the air-fuel ratio control without performing the correction by the feedback control, for example, it is possible to suppress an increase in fuel consumption. Further, by warning the driver, repair at a dealer or the like can be promoted, and emission of harmful gas to the atmosphere can be suppressed.
【００１１】[0011]
【実施例】以下、本発明の一実施例を図面により説明す
る。図１は本発明の一実施例の全体構成を示している。
内燃機関４への吸入空気量Ｑａは絞り弁２により調整さ
れ空気流量センサ１により計測される。また、内燃機関
４の回転速度Ｎｅは回転速度センサ３により計測され
る。排気ガスは排気管５を経て、触媒６に至りさらに排
気管７を経て大気に放出される。排気管５および７には
それぞれ酸素濃度センサ８、９が配置されている。これ
ら各種センサの出力は制御装置１０に入力される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of an embodiment of the present invention.
The intake air amount Qa to the internal combustion engine 4 is adjusted by the throttle valve 2 and measured by the air flow rate sensor 1. The rotation speed Ne of the internal combustion engine 4 is measured by the rotation speed sensor 3. The exhaust gas passes through the exhaust pipe 5, reaches the catalyst 6, and further passes through the exhaust pipe 7 to be released to the atmosphere. Oxygen concentration sensors 8 and 9 are arranged in the exhaust pipes 5 and 7, respectively. The outputs of these various sensors are input to the control device 10.
【００１２】空燃比フィードバック制御手段１１へは空
気流量センサ１と回転速度センサ３および酸素濃度セン
サ８の出力が入力され、下式により燃料噴射パルス幅Ｔ
ｉが計算され、このＴｉに基づき図示しないインジェク
タに駆動パルスが出力され、燃料が供給される。The outputs of the air flow rate sensor 1, the rotation speed sensor 3 and the oxygen concentration sensor 8 are input to the air-fuel ratio feedback control means 11, and the fuel injection pulse width T is calculated by the following equation.
i is calculated, a drive pulse is output to an injector (not shown) based on this Ti, and fuel is supplied.
【００１３】Ｔｉ＝Ｋ×Ｔｐ×α＋Ｔｂ
Ｋ ：係数（冷却水温や加減速による補正）
Ｔｐ：基本噴射パルス幅
α ：フィードバック補正係数
Ｔｂ：無効噴射パルス幅
ここに
Ｔｐ＝ｋ×Ｑａ／Ｎｅ
ｋ ：係数（インジェクタの特性等による）
さらにフィードバック補正係数αは、酸素濃度センサ８
が空燃比リーンを示している場合徐々に大きく、すなわ
ち燃料供給量が多くなるように、空燃比リッチを示して
いる場合には徐々に小さく、すなわち燃料供給量が少な
くなるように計算され、燃料供給量を補正している。通
常は１付近の値となっている。Ti = K × Tp × α + Tb K: Coefficient (correction by cooling water temperature or acceleration / deceleration) Tp: Basic injection pulse width α: Feedback correction coefficient Tb: Invalid injection pulse width Tp = k × Qa / Ne k: Coefficient (depending on the characteristics of the injector, etc.) Further, the feedback correction coefficient α is
Is gradually increased when the air-fuel ratio is lean, that is, the fuel supply amount increases, and gradually decreases when the air-fuel ratio is rich, that is, the fuel supply amount decreases. The supply is being corrected. Normally, the value is around 1.
【００１４】触媒性能診断手段１２には触媒６の上下流
に配置された酸素濃度センサ８および９の出力が入力さ
れ、この２つの酸素濃度センサの出力波形の相互相関関
数により触媒６の性能すなわち有害ガスの転換効率が推
定される。この方式では触媒の性能と触媒前後酸素濃度
センサの出力波形の相互相関関数とに相関関係が有ると
いうことを利用して触媒６の性能を推定している。この
ようにして推定された触媒性能が所定の値より悪化した
場合には、運転者への警告等を行うことにより、修理を
促している。これにより有害ガスを大量に大気へ放出し
ているような状態での運転を防止しようとしている。The outputs of the oxygen concentration sensors 8 and 9 arranged upstream and downstream of the catalyst 6 are input to the catalyst performance diagnosing means 12, and the performance of the catalyst 6 is determined by the cross-correlation function of the output waveforms of these two oxygen concentration sensors. The conversion efficiency of harmful gas is estimated. In this method, the performance of the catalyst 6 is estimated by utilizing the fact that there is a correlation between the performance of the catalyst and the cross-correlation function of the output waveforms of the oxygen concentration sensor before and after the catalyst. When the catalyst performance estimated in this way becomes worse than a predetermined value, warning is given to the driver to prompt repair. This is intended to prevent operation in a state where a large amount of harmful gas is released to the atmosphere.
【００１５】リーク検出手段２０にも触媒６の上下流に
配置された酸素濃度センサ８および９の出力が入力さ
れ、この２つの酸素濃度センサの出力からリークを検出
している。The outputs of the oxygen concentration sensors 8 and 9 arranged upstream and downstream of the catalyst 6 are also input to the leak detection means 20, and the leak is detected from the outputs of these two oxygen concentration sensors.
【００１６】リーク検出手段２０によりリークが検出さ
れると、中止または補正手段（１）２１により空燃比フ
ィードバック制御が中止または補正され、中止または補
正手段（２）２２により触媒性能診断が中止または補正
される。When a leak is detected by the leak detection means 20, the air-fuel ratio feedback control is stopped or corrected by the stop or correction means (1) 21, and the catalyst performance diagnosis is stopped or corrected by the stop or correction means (2) 22. To be done.
【００１７】以下、リーク検出方法および空燃比フィー
ドバック制御と触媒性能診断の中止、補正方法について
説明する。The leak detection method, the air-fuel ratio feedback control and the method for stopping and correcting the catalyst performance diagnosis will be described below.
【００１８】まず、リーク検出方法について説明する。First, the leak detection method will be described.
【００１９】リークの発生個所により検出方法が異なる
ため、図１のＡ部（酸素濃度センサ８より上流）とＢ部
（酸素濃度センサ８と９との間）にそれぞれリークがあ
る場合に分けて説明する。Since the detection method differs depending on the location where the leak occurs, it is divided into the case where there is a leak in the section A (upstream of the oxygen concentration sensor 8) and the section B (between the oxygen concentration sensors 8 and 9) in FIG. explain.
【００２０】まずＡ部にリークがある場合、比較的低
速、低負荷時に１回毎の燃焼に同期して排気脈動により
負圧が発生し、空気が吸入され、酸素濃度センサ８の出
力波形にリーンスパイクがのる。First, when there is a leak in the portion A, negative pressure is generated due to exhaust pulsation in synchronization with each combustion at relatively low speed and low load, air is sucked, and the output waveform of the oxygen concentration sensor 8 changes. Lean spike is on.
【００２１】従って図２に示すように酸素濃度センサ８
の出力波形をフィルタ手段３１によりフィルタリングす
ることによって燃焼同期の成分を抽出し、比較的低速、
低負荷時であるということを特定運転状態検出手段３３
で検出し、そのような運転状態である場合に、フィルタ
リングされた抽出成分が所定値よりも大きい場合にはリ
ーク判定手段３２によりリークが有ると判定する。さら
には抽出成分の大きさによりリーク量を推定することも
可能である。Therefore, as shown in FIG. 2, the oxygen concentration sensor 8
The combustion-synchronous component is extracted by filtering the output waveform of the
The specific operation state detecting means 33 indicates that the load is low.
In such an operating state, if the filtered extracted component is larger than a predetermined value, the leak determination means 32 determines that there is a leak. Furthermore, it is possible to estimate the leak amount based on the size of the extracted component.
【００２２】あるいは前述したように空燃比フィードバ
ック制御手段１１で計算されるフィードバック補正係数
αによってもリークの検出が可能である。すなわちリー
クがある場合には、酸素濃度センサ８の位置において空
燃比が理論空燃比となるように、リークにより吸入され
た酸素に見合う分αが大きな値となる。従って、図３に
示すようにα計算手段の計算結果を用い、先程の場合同
様に特定運転状態の時のαの値が大きい場合リークが有
ると判定する。さらにはαの値の大きさによりリーク量
を推定することも可能である。Alternatively, as described above, the leak can be detected also by the feedback correction coefficient α calculated by the air-fuel ratio feedback control means 11. That is, when there is a leak, the amount α corresponding to the oxygen taken in by the leak becomes a large value so that the air-fuel ratio becomes the stoichiometric air-fuel ratio at the position of the oxygen concentration sensor 8. Therefore, as shown in FIG. 3, using the calculation result of the α calculation means, it is determined that there is a leak when the value of α in the specific operation state is large as in the case described above. Furthermore, it is possible to estimate the leak amount based on the magnitude of the value of α.
【００２３】これらの例では排気脈動に負圧が発生しな
いような領域における値と比較することによってリーク
以外のバラツキ等の要因を排除するようにした方がさら
に好ましい。In these examples, it is more preferable to eliminate the factors other than the leakage, such as variations, by comparing with a value in a region where negative pressure does not occur in the exhaust pulsation.
【００２４】次にＢ部にリークがある場合について説明
する。この場合酸素濃度センサ８の位置においては空燃
比は理論空燃比にフィードバック制御される。ところ
が、Ａ部にリークがある場合と同様に、比較的低速、低
負荷時には空気が吸入されるため酸素濃度センサ９の位
置では酸素過剰状態となる。Next, the case where there is a leak in the portion B will be described. In this case, at the position of the oxygen concentration sensor 8, the air-fuel ratio is feedback-controlled to the stoichiometric air-fuel ratio. However, as in the case where there is a leak in the portion A, air is sucked in at a relatively low speed and a low load, so that the oxygen concentration sensor 9 is in an oxygen excess state.
【００２５】リーク検出のフローの例を図４に示す。先
ずステップＳ１０１において特定運転状態かどうかを調
べる。Ｎｏならフローを終了し、Ｙｅｓの場合だけステ
ップＳ１０２に進み、触媒６の後流に配置されている酸
素濃度センサ９の出力を調べる。リッチを示している場
合ステップＳ１０３は進みリーク無しと判定する。リッ
チを示していない場合、ステップＳ１０４からステップ
Ｓ１０６のフローによりリミッタの範囲内で徐々に酸素
濃度センサ９がリッチを示すまでリッチシフトを行う。
リッチシフトは例えば酸素濃度センサ８による空燃比フ
ィードバック制御を行う場合の酸素濃度センサ８の出力
のリッチ／リーン判定電圧を上げていくことにより可能
である。ステップＳ１０７で酸素濃度センサ９がリッチ
に反転したときのリッチシフト量からリーク量を推定す
る。ステップＳ１０８からステップＳ１１０では、この
推定リーク量が所定値を超えていればリーク有りと判定
し、そうでなければリーク無しと判定する。この様な方
式の場合、例えば触媒上流の空燃比をリッチシフトして
も触媒がその影響をなまらせてしまうため、触媒後流の
酸素濃度センサ９に影響が現れるまでかなりの時間を要
すことがある。従ってリッチシフト時には結果を調べる
までに所定の時間をおいた方が良い。また、このような
リッチシフトは場合によっては排気ガス中の有害成分を
多少なりとも増大する可能性がある。従って、リーク検
出の頻度は所定回以内に制限した方が良い。An example of the flow of leak detection is shown in FIG. First, in step S101, it is checked whether or not the operation state is the specific operation state. If No, the flow is ended, and if Yes, the process proceeds to step S102, and the output of the oxygen concentration sensor 9 arranged downstream of the catalyst 6 is checked. If it indicates rich, step S103 proceeds and it is determined that there is no leak. When the rich is not indicated, the rich shift is performed until the oxygen concentration sensor 9 gradually indicates the rich within the limiter range by the flow of steps S104 to S106.
The rich shift can be performed by, for example, increasing the rich / lean determination voltage of the output of the oxygen concentration sensor 8 when performing the air-fuel ratio feedback control by the oxygen concentration sensor 8. In step S107, the leak amount is estimated from the rich shift amount when the oxygen concentration sensor 9 is inverted to rich. In steps S108 to S110, if the estimated leak amount exceeds a predetermined value, it is determined that there is a leak, and if not, it is determined that there is no leak. In the case of such a system, for example, even if the air-fuel ratio upstream of the catalyst is rich-shifted, the effect of the catalyst is blunted. Therefore, it takes a considerable time for the oxygen concentration sensor 9 downstream of the catalyst to be affected. There is. Therefore, at the time of rich shift, it is better to allow a predetermined time before checking the result. Further, such a rich shift may increase the harmful components in the exhaust gas to some extent in some cases. Therefore, it is better to limit the frequency of leak detection within a predetermined number of times.
【００２６】また、他の方法として触媒が活性化する前
に酸素濃度センサ８と９との出力を比較するようにして
も良い。この場合リーク検出の頻度は少なくなるが、触
媒の影響を受けにくく、リッチシフトを行う必要がない
という利点がある。As another method, the outputs of the oxygen concentration sensors 8 and 9 may be compared before the catalyst is activated. In this case, the frequency of leak detection is low, but there is an advantage that it is not easily affected by the catalyst and it is not necessary to perform rich shift.
【００２７】以上説明したように、リークの発生位置お
よびリーク量を推定することが可能である。As described above, it is possible to estimate the leak occurrence position and the leak amount.
【００２８】次にリーク検出時の空燃比フィードバック
制御と触媒性能診断等の中止、補正方法について説明す
る。Next, the method of stopping and correcting the air-fuel ratio feedback control and the catalyst performance diagnosis at the time of leak detection will be described.
【００２９】まず、リーク発生個所が図１のＡ部の場
合、前述のようにαが大きな値となって燃料を増量して
しまうため、燃料消費量の増大を招いてしまう。また、
増量された燃料は、酸素が不足しているため内燃機関の
燃焼室内では燃焼せず、リーク発生個所より後流の排気
管や触媒で燃焼する。このため触媒の温度が上がり過ぎ
て性能が劣化してしまう可能性がある。First, in the case where the leak-occurring portion is the portion A in FIG. 1, since α becomes a large value and the amount of fuel is increased as described above, the amount of fuel consumption is increased. Also,
The increased amount of fuel does not burn in the combustion chamber of the internal combustion engine due to lack of oxygen, and burns in the exhaust pipe and the catalyst downstream of the leak occurrence point. Therefore, there is a possibility that the temperature of the catalyst rises excessively and the performance deteriorates.
【００３０】従って、空燃比フィードバック制御の中
止、補正方法については、リークを検出したら基本的に
は空燃比フィードバック制御を中止し、フィードバック
補正係数αを１に固定するようにすることが好ましい。
ただし、この場合触媒６では排気ガスは酸素過剰状態と
なるのでＮＯｘの転換効率が落ち、大気に放出される量
は増えてしまう。従って、運転者への警告を併せて行う
ようにすることが好ましい。Therefore, as for the method of stopping and correcting the air-fuel ratio feedback control, it is preferable to basically stop the air-fuel ratio feedback control when the leak is detected and fix the feedback correction coefficient α to 1.
However, in this case, since the exhaust gas in the catalyst 6 is in an oxygen excess state, the conversion efficiency of NOx is lowered and the amount released to the atmosphere is increased. Therefore, it is preferable to also give a warning to the driver.
【００３１】さらにはリークの量に応じてリーク量が比
較的少ないときは図５に示すようにαの固定値をよりも
多少大きめにして、触媒の温度をあまり上げ過ぎない範
囲で燃料を増量し、ＮＯｘの転換効率をある程度確保す
るようにしても良い。Further, when the leak amount is relatively small according to the leak amount, the fixed value of α is set to be slightly larger than that shown in FIG. 5, and the amount of fuel is increased within a range in which the temperature of the catalyst is not raised too much. However, the NOx conversion efficiency may be secured to some extent.
【００３２】また、フィードバック制御を中止せずに、
リーンシフトをかけることにより触媒等で燃焼する燃料
量を少なくし、触媒の温度上昇を抑えることも可能であ
る。次に、触媒の性能診断の中止、補正方法について説
明する。前述のような触媒前後の酸素濃度センサ出力の
相関関数により触媒の性能を推定する方式においては、
リークの量が比較的少ないときには、リークの無い場合
に比べ、触媒温度が高い等の理由により相関関数が小さ
め、すなわち触媒性能が実際よりも良い側に判定される
傾向がある。また、リークの量が所定値以上になってく
ると空燃比変動幅が通常より大きくなるため、今度は相
関関数が大きめとなってしまう。従って、例えば図６に
示すような補正係数を相関関数にかけて触媒の性能診断
を行うようにすれば良い。また、リーク量が所定量を超
えるような場合、診断の精度が確保できなくなるので、
診断を中止する。Further, without stopping the feedback control,
By applying lean shift, it is possible to reduce the amount of fuel burned by the catalyst or the like and suppress the temperature rise of the catalyst. Next, a method of stopping and correcting the performance diagnosis of the catalyst will be described. In the method of estimating the performance of the catalyst by the correlation function of the oxygen concentration sensor output before and after the catalyst as described above,
When the amount of leak is relatively small, the correlation function tends to be small, that is, the catalyst performance is judged to be better than it is because the catalyst temperature is higher than when there is no leak. Further, when the amount of leak exceeds a predetermined value, the fluctuation range of the air-fuel ratio becomes larger than usual, so that the correlation function becomes large this time. Therefore, for example, the correction coefficient as shown in FIG. 6 may be applied to the correlation function to perform the performance diagnosis of the catalyst. Also, if the leak amount exceeds a predetermined amount, the accuracy of diagnosis cannot be ensured.
Stop the diagnosis.
【００３３】次に、酸素濃度センサ診断の中止、補正方
法については、例えば出力波形から応答速度を診断する
場合に、前述のように出力波形にリーンスパイクがのる
ため、応答性を速い側（応答時間を短い側）に判定して
しまう。従って、例えば図７に示すような補正係数を応
答時間にかけて酸素濃度センサの応答性診断を行うよう
にすれば良い。また、リーク量が所定量を超えるような
場合、診断結果がばらつき精度が確保できなくなるの
で、診断を中止する。Next, regarding the method of stopping and correcting the oxygen concentration sensor diagnosis, for example, when the response speed is diagnosed from the output waveform, the lean response spikes on the output waveform as described above, so that the response is faster ( The response time is shorter). Therefore, for example, the response coefficient of the oxygen concentration sensor may be diagnosed over the response time using the correction coefficient as shown in FIG. Further, when the leak amount exceeds a predetermined amount, the accuracy of variation in the diagnosis result cannot be ensured, so the diagnosis is stopped.
【００３４】次にリーク発生個所が図１のＢ部の場合に
ついて説明する。Next, the case where the leak occurs at the portion B in FIG. 1 will be described.
【００３５】この場合、特に触媒の上流の場合、前述の
ように、酸素濃度センサ８の位置では理論空燃比になる
ようフィードバック制御されるが、触媒６位置において
は酸素過剰状態となる。このため、ＮＯｘの転換されず
大気に放出される。また、酸素濃度センサ９が常にリー
ン状態を示してしまうため、触媒６の性能診断ができな
くなったり、誤診断したりしてしまう。さらには酸素濃
度センサ９の信号も利用して空燃比をフィードバック制
御するような装置の場合、Ａ位置にリークがある場合同
様に燃料消費料の増大、触媒の過熱等が発生する。In this case, particularly upstream of the catalyst, as described above, feedback control is performed so that the stoichiometric air-fuel ratio is obtained at the position of the oxygen concentration sensor 8, but the oxygen excess state is obtained at the position of the catalyst 6. Therefore, NOx is not converted and is released into the atmosphere. Moreover, since the oxygen concentration sensor 9 always shows a lean state, the performance diagnosis of the catalyst 6 cannot be performed or an erroneous diagnosis is performed. Further, in the case of a device that also feedback-controls the air-fuel ratio using the signal of the oxygen concentration sensor 9, the fuel consumption increases, the catalyst overheats, and the like as in the case where there is a leak at the position A.
【００３６】従って、（酸素濃度センサ８による）空燃
比フィードバック制御については、例えば、リークを検
出したらＮＯｘの大気への放出を抑えるためにリッチシ
フトをかけながら空燃比フィードバック制御を行うか、
空燃比フィードバック制御を中止し、αを１より大きめ
の値に固定する。いずれにしても、リーク量が所定量を
超えると急激にＮＯｘの転換効率が落ち、大気に放出さ
れる量が急増するので、運転者への警告を併せて行うよ
うにすることが好ましい。Therefore, regarding the air-fuel ratio feedback control (by the oxygen concentration sensor 8), for example, if a leak is detected, the air-fuel ratio feedback control is performed while performing a rich shift in order to suppress the release of NOx to the atmosphere.
The air-fuel ratio feedback control is stopped and α is fixed to a value larger than 1. In any case, when the leak amount exceeds a predetermined amount, the conversion efficiency of NOx sharply decreases and the amount released to the atmosphere increases rapidly. Therefore, it is preferable to also give a warning to the driver.
【００３７】酸素濃度センサ９を用いた空燃比フィード
バック制御については、触媒の過熱を防ぐためフィード
バックを中止する。Regarding the air-fuel ratio feedback control using the oxygen concentration sensor 9, the feedback is stopped to prevent overheating of the catalyst.
【００３８】触媒の性能診断については、前述のような
触媒前後の酸素濃度センサ出力の相関関数により触媒の
性能を推定する方式においては、リークの量が比較的少
ない場合でも触媒後の酸素濃度センサ９の出力が常にリ
ーンを示すので相関関数は非常に小さい値となり。劣化
している触媒でも劣化していないと判定してしまう。従
って、リーク量が少ない場合であっても触媒の診断を中
止する。Regarding the catalyst performance diagnosis, in the method of estimating the catalyst performance by the correlation function of the oxygen concentration sensor output before and after the catalyst as described above, the oxygen concentration sensor after the catalyst is detected even if the amount of leak is relatively small. Since the output of 9 always shows lean, the correlation function becomes a very small value. Even a deteriorated catalyst is determined not to be deteriorated. Therefore, the catalyst diagnosis is stopped even if the leak amount is small.
【００３９】酸素濃度センサ９の診断についても、出力
が常にリーンを示すので診断を中止する。The diagnosis of the oxygen concentration sensor 9 is also stopped because the output always shows lean.
【００４０】以上説明した、中止および補正方法はあく
までも例を示したものであって、当然のことながら、元
々の制御方法診断方法等により、最適な方法が異なる。
例えば触媒の耐熱性が高い場合には多少温度を上げても
排気ガスの悪化を抑える方を重視することも可能であ
る。The canceling and correcting methods described above are merely examples, and the optimum method naturally varies depending on the original control method diagnostic method and the like.
For example, when the heat resistance of the catalyst is high, it is possible to place importance on suppressing the deterioration of exhaust gas even if the temperature is raised to some extent.
【００４１】また、内燃機関の運転状態によっても影響
を受ける。例えば吸気脈動に負圧が発生しないような運
転領域においては、特に、中止および補正は必要無いの
で、例えば診断のための運転領域をそのような領域に限
定あるいは変更するようにしても良い。It is also affected by the operating state of the internal combustion engine. For example, in the operating region in which the negative pressure does not occur in the intake pulsation, there is no particular need to stop and correct, so that the operating region for diagnosis may be limited or changed to such a region.
【００４２】図８に他の実施例を示す。触媒６の前後に
排気ガス温度センサ４１および４２を配置し、触媒性能
診断手段１２により検出された温度差から触媒６の性能
を診断する。この場合も上述の様に、リークにより触媒
の温度が異常に上昇する場合が有るので、このような場
合、診断を中止または補正する。酸素濃度センサに代え
てＨＣセンサ使用してＨＣ濃度を計ることによっても排
気制御装置を実現することができる。また、酸素濃度セ
ンサに代えてＮｏｘセンサを使用してＮｏｘ濃度を計る
ことによっても、排気制御装置を実現することができ
る。FIG. 8 shows another embodiment. Exhaust gas temperature sensors 41 and 42 are arranged before and after the catalyst 6, and the performance of the catalyst 6 is diagnosed from the temperature difference detected by the catalyst performance diagnosing means 12. Also in this case, as described above, the temperature of the catalyst may rise abnormally due to the leak, and in such a case, the diagnosis is stopped or corrected. The exhaust control device can also be realized by using an HC sensor instead of the oxygen concentration sensor to measure the HC concentration. The exhaust control device can also be realized by measuring the Nox concentration using a Nox sensor instead of the oxygen concentration sensor.
【００４３】[0043]
【発明の効果】以上説明したように、本発明によれば、
排気系のリークの場所と量を検出し、その結果に基づき
空燃比フィードバック制御や触媒、酸素濃度センサの診
断を中止または補正することができる。これによって、
触媒の過熱による劣化や、排気ガスの悪化、排気浄化系
部品の誤診断を抑えることが可能である。これらは全て
有害ガスの大気への放出を防止することにつながる。As described above, according to the present invention,
It is possible to detect the location and amount of leak in the exhaust system, and stop or correct the air-fuel ratio feedback control and the diagnosis of the catalyst and oxygen concentration sensor based on the result. by this,
It is possible to suppress deterioration due to overheating of the catalyst, deterioration of exhaust gas, and erroneous diagnosis of exhaust purification system parts. All of these help prevent the release of harmful gases into the atmosphere.
【図１】本発明の一実施例の全体構成を示す図面。FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.
【図２】リーク検出手段の一例を示す図面。FIG. 2 is a diagram showing an example of a leak detection unit.
【図３】リーク検出手段の一例を示す図面。FIG. 3 is a diagram showing an example of a leak detection unit.
【図４】リーク検出のフローの例を示す図面。FIG. 4 is a diagram showing an example of a flow of leak detection.
【図５】リーク量とαの固定値との関係を示す図面。FIG. 5 is a diagram showing a relationship between a leak amount and a fixed value of α.
【図６】リーク量と触媒診断用補正係数との関係を示す
図面。FIG. 6 is a diagram showing a relationship between a leak amount and a correction coefficient for catalyst diagnosis.
【図７】リーク量と酸素濃度センサ診断用補正係数との
関係を示す図面。FIG. 7 is a diagram showing a relationship between a leak amount and an oxygen concentration sensor diagnostic correction coefficient.
【図８】他の実施例を示す図面。FIG. 8 is a view showing another embodiment.
【符号の説明】 ８、９：酸素濃度センサ １１：空燃比フィードバック制御手段 １２：触媒性能診断手段 ２０：リーク検出手段 ２１、２２：中止または補正手段。[Explanation of symbols] 8, 9: Oxygen concentration sensor 11: Air-fuel ratio feedback control means 12: Catalyst performance diagnostic means 20: Leak detection means 21, 22: Stopping or correcting means.
─────────────────────────────────────────────────────
─────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成１４年８月２８日（２００２．８．２
８）[Submission date] August 28, 2002 (2002.8.2)
8)
【手続補正１】[Procedure Amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】特許請求の範囲[Name of item to be amended] Claims
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【特許請求の範囲】[Claims]
───────────────────────────────────────────────────── 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 41/22 ３０５ Ｆ０２Ｄ 41/22 ３０５Ｋ Ｆターム(参考） 3G084 BA24 BA33 DA00 DA10 DA12 DA27 DA28 EB16 EB22 FA00 FA07 FA30 FA33 3G091 AA17 AB03 BA00 BA08 BA21 BA34 DC01 EA00 EA01 EA05 EA34 HA36 HA37 3G301 JA00 JA08 JA21 JA33 JB09 JB10 MA01 NA08 ND01 ND15 ND17 PA01Z PD00Z PD02A PD02Z PD09Z PE01Z ─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI theme code (reference) F02D 41/22 305 F02D 41/22 305K F term (reference) 3G084 BA24 BA33 DA00 DA10 DA12 DA27 DA28 EB16 EB22 FA00 FA07 FA30 FA33 3G091 AA17 AB03 BA00 BA08 BA21 BA34 DC01 EA00 EA01 EA05 EA34 HA36 HA37 3G301 JA00 JA08 JA21 JA33 JB09 JB10 MA01 NA08 ND01 ND15 ND17 PA01Z PD00Z PD02A PD02Z PD09Z PE01Z
Claims (5)
設けられ、空燃比フィードバック制御手段と触媒性能診
断手段とが設けられ、および排気系に排気ガスセンサが
設けられて排気ガスのリークを検出するようにした排気
ガス制御装置において、 前記排気ガスセンサを、触媒等排気浄化装置の上流側お
よび後流側の排気系にそれぞれ設けて、触媒等排気浄化
装置の上流側および触媒等排気浄化装置のリークをそれ
ぞれ検出し、 検出された信号によって排気ガス成分検出を中止または
検出値を補正する検出中止または補正手段を設け、 前記空燃比フィードバック制御手段または触媒性能診断
手段を検出中止または補正手段からの検出中止または補
正信号によってそれぞれ制御することを特徴とする制御
装置。1. An exhaust gas purification device for a catalyst and the like is provided in an exhaust system of an internal combustion engine, an air-fuel ratio feedback control means and a catalyst performance diagnosing means are provided, and an exhaust gas sensor is provided in the exhaust system to prevent an exhaust gas leak. In the exhaust gas control device for detecting, the exhaust gas sensor is provided in each of an exhaust system on an upstream side and a downstream side of an exhaust purification device for a catalyst and the like, and an upstream side of the exhaust purification device for a catalyst and an exhaust purification device for a catalyst. The detection of the exhaust gas component detection is stopped or the detection value is corrected according to the detected signal, and the detection stop or correction means is provided, and the air-fuel ratio feedback control means or the catalyst performance diagnosis means is detected or stopped from the detection means. 2. A control device, which is controlled by stop detection or correction signal of each.
設けられ、空燃比フィードバック制御手段と触媒性能診
断手段とが設けられ、および排気系に排気ガスセンサが
設けられて排気ガスのリークを検出するようにした排気
ガス制御装置において、 前記排気ガスセンサを、触媒等排気浄化装置の上流側お
よび後流側の排気系にそれぞれ設けて、触媒等排気浄化
装置の上流側および触媒等排気浄化装置のリークをそれ
ぞれ異手段により検出し、 検出された信号によって排気ガス成分検出を中止または
検出値を補正する検出中止または補正手段を設け、 前記空燃比フィードバック制御手段または触媒性能診断
手段を検出中止または補正手段からの検出中止または補
正信号によってそれぞれ制御することを特徴とする制御
装置。2. An exhaust gas purification device for a catalyst and the like is provided in an exhaust system of an internal combustion engine, an air-fuel ratio feedback control means and a catalyst performance diagnosing means are provided, and an exhaust gas sensor is provided in the exhaust system to prevent exhaust gas leakage. In the exhaust gas control device for detecting, the exhaust gas sensor is provided in each of an exhaust system on an upstream side and a downstream side of an exhaust purification device for a catalyst and the like, and an upstream side of the exhaust purification device for a catalyst and an exhaust purification device for a catalyst. The leak of each of them is detected by different means, and the detection stop or correction means for stopping the exhaust gas component detection or correcting the detected value by the detected signal is provided, and the detection of the air-fuel ratio feedback control means or the catalyst performance diagnosis means is stopped or A control device, which is controlled by the detection stop or the correction signal from the correction means, respectively.
設けられ、空燃比フィードバック制御手段と触媒性能診
断手段とが設けられ、および排気系に排気ガスセンサが
設けられて排気ガスのリークを検出するようにした排気
ガス制御装置において、 前記排気ガスセンサを、触媒等排気浄化装置の上流側お
よび後流側の排気系にそれぞれ設けて、触媒等排気浄化
装置の上流側および触媒等排気浄化装置のリークをそれ
ぞれ検出し、この場合に、上流側における前記リーク
は、空燃比をリッチシフトして排気ガスセンサがリッチ
に反転した時のリッチシフト量から検出し、 検出された信号によって排気ガス成分検出を中止または
検出値を補正する検出中止または補正手段を設け、 前記空燃比フィードバック制御手段または触媒性能診断
手段を検出中止または補正手段からの検出中止または補
正信号によってそれぞれ制御することを特徴とする制御
装置。3. An exhaust gas purification device for a catalyst and the like is provided in an exhaust system of an internal combustion engine, an air-fuel ratio feedback control means and a catalyst performance diagnosing means are provided, and an exhaust gas sensor is provided in the exhaust system to prevent an exhaust gas leak. In the exhaust gas control device for detecting, the exhaust gas sensor is provided in each of an exhaust system on an upstream side and a downstream side of an exhaust purification device for a catalyst and the like, and an upstream side of the exhaust purification device for a catalyst and an exhaust purification device for a catalyst. In this case, the leak on the upstream side is detected from the rich shift amount when the exhaust gas sensor is reversed to rich by shifting the air-fuel ratio to rich, and the detected exhaust gas component is detected by the detected signal. A detection stop or correction means for stopping or correcting the detected value is provided to detect the air-fuel ratio feedback control means or the catalyst performance diagnosis means. Control device and controls, respectively, by detecting stop or correction signals from aborted or correction means.
設けられ、空燃比フィードバック制御手段と触媒性能診
断手段とが設けられ、および排気系に排気ガスセンサが
設けられて排気ガスのリークを検出するようにした排気
ガス制御装置において、 前記排気ガスセンサを、触媒等排気浄化装置の上流側お
よび後流側の排気系にそれぞれ設けて、触媒等排気浄化
装置の上流側および触媒等排気浄化装置のリークをそれ
ぞれ検出し、この場合に、 Ｔｉ＝Ｋ×Ｔｐ×α＋Ｔｂ Ｋ ：係数（冷却水温や加減速による補正） Ｔｐ：基本噴射パルス幅 α ：フィードバック補正係数 Ｔｂ：無効噴射パルス幅 としたときに、αの大きさをみてリークを検出し、 検出された信号によって排気ガス成分検出を中止または
検出値を補正する検出中止または補正手段を設け、 前記空燃比フィードバック制御手段または触媒性能診断
手段を検出中止または補正手段からの検出中止または補
正信号によってそれぞれ制御することを特徴とする制御
装置。4. An exhaust gas purification device for a catalyst and the like is provided in an exhaust system of an internal combustion engine, an air-fuel ratio feedback control means and a catalyst performance diagnosing means are provided, and an exhaust gas sensor is provided in the exhaust system to prevent an exhaust gas leak. In the exhaust gas control device for detecting, the exhaust gas sensor is provided in each of an exhaust system on an upstream side and a downstream side of an exhaust purification device for a catalyst and the like, and an upstream side of the exhaust purification device for a catalyst and an exhaust purification device for a catalyst. In this case, Ti = K × Tp × α + Tb K: coefficient (correction by cooling water temperature or acceleration / deceleration) Tp: basic injection pulse width α: feedback correction coefficient Tb: invalid injection pulse width In addition, a detection stop or correction means for detecting the leak by observing the value of α and stopping the exhaust gas component detection or correcting the detected value according to the detected signal is provided. Only, a control device and controls, respectively, by detecting stop or correction signals from the detection cancel or correct means the air-fuel ratio feedback control means or catalyst performance diagnostic means.
設けられ、空燃比フィードバック制御手段と触媒性能診
断手段とが設けられ、および排気系に排気ガスセンサが
設けられて排気ガスのリークを検出するようにした排気
ガス制御装置において、 前記排気ガスセンサを、触媒等排気浄化装置の上流側お
よび後流側の排気系にそれぞれ設けて、触媒等排気浄化
装置の上流側および触媒等排気浄化装置のリークをそれ
ぞれ検出し、 検出された信号によって排気ガス成分検出を中止または
検出値を補正する検出中止または補正手段を設け、 前記空燃比フィードバック制御手段または触媒性能診断
手段を検出中止または補正手段からの検出中止信号によ
ってそれぞれ中止制御することを特徴とする制御装置。5. An exhaust gas purification device for a catalyst and the like is provided in an exhaust system of an internal combustion engine, an air-fuel ratio feedback control means and a catalyst performance diagnosis means are provided, and an exhaust gas sensor is provided in the exhaust system to prevent exhaust gas leakage. In the exhaust gas control device for detecting, the exhaust gas sensor is provided in each of an exhaust system on an upstream side and a downstream side of an exhaust purification device for a catalyst and the like, and an upstream side of the exhaust purification device for a catalyst and an exhaust purification device for a catalyst. The detection of the exhaust gas component detection is stopped or the detection value is corrected according to the detected signal, and the detection stop or correction means is provided, and the air-fuel ratio feedback control means or the catalyst performance diagnosis means is detected or stopped from the detection means. A control device characterized in that stop control is performed by each detection stop signal.
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|---|---|---|---|
| JP2002219469A JP4000937B2 (en) | 2002-07-29 | 2002-07-29 | Exhaust control device for internal combustion engine |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002219469A JP4000937B2 (en) | 2002-07-29 | 2002-07-29 | Exhaust control device for internal combustion engine |
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|---|---|---|---|
| JP32242894A Division JP3467657B2 (en) | 1994-12-26 | 1994-12-26 | Exhaust control device for internal combustion engine |
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|---|---|
| JP2003097341A true JP2003097341A (en) | 2003-04-03 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009293413A (en) * | 2008-06-03 | 2009-12-17 | Nissan Motor Co Ltd | Erroneous control determining device and erroneous control determining method for air/fuel ratio control system |
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2002
- 2002-07-29 JP JP2002219469A patent/JP4000937B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009293413A (en) * | 2008-06-03 | 2009-12-17 | Nissan Motor Co Ltd | Erroneous control determining device and erroneous control determining method for air/fuel ratio control system |
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