JPH0979028A - Self-diagnostic device for catalyst - Google Patents

Self-diagnostic device for catalyst

Info

Publication number
JPH0979028A
JPH0979028A JP7232927A JP23292795A JPH0979028A JP H0979028 A JPH0979028 A JP H0979028A JP 7232927 A JP7232927 A JP 7232927A JP 23292795 A JP23292795 A JP 23292795A JP H0979028 A JPH0979028 A JP H0979028A
Authority
JP
Japan
Prior art keywords
catalyst
sensor
output
downstream
self
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
Application number
JP7232927A
Other languages
Japanese (ja)
Other versions
JP3588662B2 (en
Inventor
Kuniaki Sawamoto
国章 沢本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Priority to JP23292795A priority Critical patent/JP3588662B2/en
Publication of JPH0979028A publication Critical patent/JPH0979028A/en
Application granted granted Critical
Publication of JP3588662B2 publication Critical patent/JP3588662B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0835—Hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/18—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being an adsorber or absorber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/03—Monitoring or diagnosing the deterioration of exhaust systems of sorbing activity of adsorbents or absorbents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/12—Hydrocarbons
    • 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
    • Y02T10/12—Improving ICE efficiencies

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  • 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)

Abstract

PROBLEM TO BE SOLVED: To diagnose the cold time HC adsorbing capacity of an HC adsorbing catalyst and a lean NOx catalyst and HC desorbing capacity from the cold time to warming up. SOLUTION: Signals from an O2 sensor A on the upper reaches and an O2 sensor B on the lower reaches are inputted to a signal comparing circuit D, and the output of a water temperature sensor C and the signal comparing circuit D is inputted to a catalyst degradation circuit E to judge degradation. An alarm circuit F lights a light emission diode at the time of judging catalyst degradation. Since a catalyst for adsorbing HC at the cold time and desorbing HC after warming up is diagnosed from the ratio of rich time of the O2 sensors A, B on the upper and lower reaches, the catalyst can be diagnosed respectively at the time of adsorption and desorption so as to improve the accuracy of diagnosis.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、リーンＮＯｘ触媒
やＨＣ吸着触媒のように冷間時にＨＣを吸着する触媒の
リーンＮＯｘ転換・ＨＣ吸着性能の診断法を特徴とした
触媒の自己診断装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst self-diagnosis device characterized by a method for diagnosing lean NOx conversion and HC adsorption performance of a catalyst that adsorbs HC when cold such as a lean NOx catalyst or an HC adsorption catalyst. .

【０００２】[0002]

【従来の技術】従来の触媒の自己診断装置としては、例
えば特開平６−６６１３１号公報があり、これはＨＣ吸
着触媒の自己診断法を示す。2. Description of the Related Art As a conventional catalyst self-diagnosis apparatus, for example, there is JP-A-6-66131, which shows a self-diagnosis method for an HC adsorption catalyst.

【０００３】また触媒材料としては、特開平３−１３５
４３７号公報と特開平６−２０５９７５号公報等に示す
ものがある。Further, as a catalyst material, JP-A-3-135 is known.
437 and Japanese Patent Laid-Open No. 6-205975.

【０００４】[0004]

【発明が解決しようとする課題】しかしながら、このよ
うな従来の触媒の自己診断装置にあっては、暖機後の触
媒上下流Ｏ2 センサの周波数比から診断を検出する方法
（吸着材の三元触媒能力から吸着材の吸着能力を診断す
る）となっていたため、吸着性能と三元触媒性能の相関
が低いと診断の精度が低下するという問題があった。However, in such a conventional catalyst self-diagnosis apparatus, a method of detecting the diagnosis from the frequency ratio of the upstream and downstream O 2 sensor of the catalyst after warming up (three of the adsorbents) is used. Since the adsorption ability of the adsorbent is diagnosed from the original catalyst ability), there is a problem that the accuracy of the diagnosis decreases if the correlation between the adsorption performance and the three-way catalyst performance is low.

【０００５】本発明は、このような従来の問題点に着目
してなされたもので、ＨＣ吸着触媒やリーンＮＯｘ触媒
の冷間時のＨＣ吸着能力と冷間時から暖機までの間のＨ
Ｃ脱離能力とを診断する触媒の自己診断装置を提供する
ことを目的としている。The present invention has been made by paying attention to such a conventional problem, and the HC adsorbing ability of the HC adsorbing catalyst or the lean NOx catalyst in the cold state and the H adsorbing capacity from the cold state to the warming up time.
It is an object of the present invention to provide a catalyst self-diagnosis device for diagnosing C desorption capacity.

【０００６】[0006]

【課題を解決するための手段】本発明は上述の課題を解
決するために、機関の排気管に装着された触媒の排気上
下流にＯ2 センサを装着し、ラムダコントロール条件に
おける両Ｏ2 センサの周波数比から触媒の劣化を診断す
る装置において、機関の始動から暖機に至る間に、触媒
上流のＯ2 センサ出力が変化しても、下流のＯ2 センサ
出力がリッチ出力を示す事により、触媒の性能が良い事
を診断する。SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention mounts an O 2 sensor upstream and downstream of a catalyst mounted on an exhaust pipe of an engine, and both O 2 sensors under a lambda control condition. In the device for diagnosing the deterioration of the catalyst from the frequency ratio of, even if the output of the O 2 sensor upstream of the catalyst changes during the period from the start of the engine to the warm-up, the output of the downstream O 2 sensor shows a rich output. , Diagnose that the performance of the catalyst is good.

【０００７】また、機関の始動から暖機に至る間に、触
媒上流のＯ2 センサ出力が変化しても、まず下流のＯ2
センサ出力がリーン出力を示す。さらに時間が経過した
ら、触媒上流のＯ2 センサ出力が変化しても下流のＯ2
センサ出力がリッチ出力を示すことにより触媒の性能が
良い事を診断する。Further, even if the output of the O 2 sensor upstream of the catalyst changes during the period from engine startup to warm-up, first of all the O 2 downstream
The sensor output shows a lean output. After lapse of further time, also O 2 sensor output upstream of the catalyst is changed downstream of the O 2
It is diagnosed that the performance of the catalyst is good because the sensor output shows a rich output.

【０００８】[0008]

【作用】本発明によれば、機関の始動から暖機に至る間
に、前記触媒上流のＯ2 センサ出力が変化しても、下流
のＯ2 センサ出力がリッチ出力を示す事により、前記触
媒の性能が良い事を診断する。According to the present invention, while leading to warm up from the start of the engine, be varied O 2 sensor output of the catalyst upstream, downstream of the O 2 sensor output by indicating the rich output, the catalyst It is diagnosed that the performance of is good.

【０００９】また、本発明によれば、機関の始動から暖
機に至る間に、前記触媒上流のＯ2センサ出力が変化し
ても、まず下流のＯ2 センサ出力がリーン出力を示し、
さらに時間が経過したら、前記触媒上流のＯ2 センサ出
力が変化しても下流のＯ2 センサ出力がリッチ出力を示
すことにより触媒の性能が良い事を診断する。Further, according to the present invention, even if the output of the O 2 sensor upstream of the catalyst changes during the period from engine startup to warm-up, the output of the downstream O 2 sensor first shows a lean output,
After a lapse of time, even if the output of the O 2 sensor upstream of the catalyst changes, the output of the O 2 sensor downstream shows a rich output, so that it is diagnosed that the performance of the catalyst is good.

【００１０】[0010]

【発明の実施の形態】以下に本発明を図面に基づいて詳
細に説明する。尚、触媒材料は従来例特開平３−１３５
４３７号公報および特開平６−２０５９７５号公報に示
したものが適用可能である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. Incidentally, the catalyst material is the conventional example JP-A-3-135.
Those disclosed in Japanese Patent Laid-Open No. 437 and Japanese Patent Laid-Open No. 6-205975 can be applied.

【００１１】図１は本発明のクレーム対応図である。FIG. 1 is a diagram corresponding to the claims of the present invention.

【００１２】図１において（Ａ）は上流側Ｏ2 センサ、
（Ｂ）は下流側Ｏ2 センサである。両者の信号は（Ｄ）
の信号比較回路に入力される。（Ｃ）は水温センサであ
り、このセンサ出力と（Ｄ）の出力とが、（Ｅ）の触媒
劣化回路とに入力されて、劣化を判定する。（Ｆ）は警
報回路であり、触媒劣化時に発光ダイオードを光らせ
る。In FIG. 1, (A) is an upstream O 2 sensor,
(B) is a downstream O 2 sensor. Both signals are (D)
Is input to the signal comparison circuit of. (C) is a water temperature sensor, and the sensor output and the output of (D) are input to the catalyst deterioration circuit of (E) to determine deterioration. (F) is an alarm circuit that lights up the light emitting diode when the catalyst deteriorates.

【００１３】〔実施の形態１〕図２は本発明の実施の形
態１を示す図である。図２において１はエンジンであ
り、吸入空気はエアフロメータ２、スロットルバルブ
３、吸気管４を経由して吸入される。５はインジェクタ
であり、燃料を供給する。６は点火プラグであり、点火
する。７は排気マニホールドであり、その下流にはフロ
ントチューブ８が連結されている。さらにフロントチュ
ーブの途中には触媒１０が装着され、その下流にはマフ
ラ１１が連結されている。１３はエアフロメータであ
り、吸入空気流量を計測する。１４はクランク角センサ
であり、エンジンのクランク角度を検出する。１５は冷
却水温センサであり、冷却水温を検出する。１６は上流
側Ｏ2 センサ、１７は下流側Ｏ2 センサである。１８は
発光ダイオードであり、故障時に点灯して警告する。１
２はコントローラであり、上記各センサの信号を演算し
て、上記各アクチュエータを駆動する。[First Embodiment] FIG. 2 is a diagram showing a first embodiment of the present invention. In FIG. 2, reference numeral 1 is an engine, and intake air is taken in through an air flow meter 2, a throttle valve 3, and an intake pipe 4. An injector 5 supplies fuel. 6 is a spark plug that ignites. Reference numeral 7 is an exhaust manifold, and a front tube 8 is connected downstream thereof. Further, a catalyst 10 is mounted in the middle of the front tube, and a muffler 11 is connected downstream thereof. An air flow meter 13 measures the intake air flow rate. A crank angle sensor 14 detects the crank angle of the engine. A cooling water temperature sensor 15 detects the cooling water temperature. Reference numeral 16 is an upstream O 2 sensor, and 17 is a downstream O 2 sensor. Reference numeral 18 denotes a light emitting diode, which lights up to warn when a failure occurs. 1
Reference numeral 2 denotes a controller, which operates the actuators by calculating signals from the sensors.

【００１４】図３は触媒が正常な場合を示す。ｔ0 の時
刻にエンジンが始動される。始動直後からλコントロー
ルを開始するために、上流Ｏ2 センサ出力は図２に示す
ように反転をくり返す。触媒が正常であれば触媒温度が
低い期間はＨＣを吸着し、触媒温度が高くなるとＨＣを
脱離する。従って、ｔ0 〜ｔ1 間はＨＣを触媒が吸着し
ている。ｔ1 〜ｔ2 間はＨＣを脱離する。この結果ｔ0
〜ｔ1 は上流Ｏ2 センサ信号が反転しているのに、下流
Ｏ2 センサ出力は低い。ｔ1 〜ｔ2 は上流Ｏ2センサ信
号が反転しているのに、下流Ｏ2 センサ出力は高い。FIG. 3 shows the case where the catalyst is normal. The engine is started at time t 0 . In order to start the λ control immediately after the start, the output of the upstream O 2 sensor repeats inversion as shown in FIG. If the catalyst is normal, it adsorbs HC while the catalyst temperature is low, and desorbs HC when the catalyst temperature is high. Therefore, the catalyst adsorbs HC during the period from t 0 to t 1 . HC is desorbed between t 1 and t 2 . This result t 0
Up to t 1, the upstream O 2 sensor signal is inverted, but the downstream O 2 sensor output is low. Although the upstream O 2 sensor signal is inverted from t 1 to t 2 , the downstream O 2 sensor output is high.

【００１５】一方、触媒が劣化している場合を、図４に
示す。図４において触媒の劣化はＨＣ吸着能の劣化と相
関を有するために、ＨＣ濃度は触媒上流と触媒下流とで
は差はない。このためＯ2 センサ出力は触媒上下流とも
に同一の周波数で反転する。時刻ｔ3 以降は三元触媒性
能が活性化して、Ｏ2 ストレージ機能が働くために、下
流Ｏ2 センサ信号の反転数は小さくなる。ｔ3 以降は診
断を行わない。On the other hand, FIG. 4 shows the case where the catalyst is deteriorated. In FIG. 4, since the deterioration of the catalyst correlates with the deterioration of the HC adsorption capacity, there is no difference in the HC concentration between the catalyst upstream and the catalyst downstream. Therefore, the O 2 sensor output is inverted at the same frequency both upstream and downstream of the catalyst. After time t 3, the three-way catalyst performance is activated and the O 2 storage function is activated, so that the inversion number of the downstream O 2 sensor signal becomes small. No diagnosis is performed after t 3 .

【００１６】このようにｔ0 →ｔ3 間で上記触媒の診断
を行う。In this way, the diagnosis of the catalyst is carried out between t 0 and t 3 .

【００１７】図５に本実施の形態のフローチャートを示
す。FIG. 5 shows a flowchart of this embodiment.

【００１８】本フローはΔＴごと（例えば５０ｍｓ）に
実行される。まずＳ１で始動終了かどうかを判定する。
ここでＮＯならＳ２に移って、ＴmS,n（始動からのタイ
アであり、ｎは添字）は０のままとする。一方、Ｓ１で
ＹＥＳならＳ３に移って、ＴmS,nをΔＴだけ増加させ
る。次にＳ４で上流のＯ2 センサ出力（ＶFO）を測定
し、さらにＳ５で下流のＯ2 センサ出力（ＶRO）を測定
する。次にＳ６でＶFOを比較値（ＳＬ）と比較して、Ａ
／Ｆが理論空燃比よりリッチかどうかを判定する。Ｙな
らリッチであるので、Ｓ７に移る。Ｓ７では上流Ｏ2 セ
ンサのリッチ累積時間（ＴmF,n，ｎは添字）をΔＴだけ
増加させる。This flow is executed every ΔT (for example, 50 ms). First, in S1, it is determined whether or not the start is completed.
If NO here, the routine proceeds to S2, and T mS, n (tire from the start, n is a subscript) remains 0. On the other hand, if YES in S1, the process proceeds to S3, and T mS, n is increased by ΔT. Next, the upstream O 2 sensor output (V FO ) is measured in S4, and the downstream O 2 sensor output (V RO ) is further measured in S5. Next, in S6, V FO is compared with the comparison value (SL), and A
It is determined whether / F is richer than the theoretical air-fuel ratio. If Y, it means rich, so move to S7. In S7, the rich accumulation time of the upstream O 2 sensor (T mF, n , n is a subscript) is increased by ΔT.

【００１９】次にＳ８ではＳ６と同様に下流Ｏ2 センサ
の出力（ＶRO）をＳＬと比較する。ＹならＳ９に移っ
て、下流Ｏ2 センサのリッチ累積時間（ＴmR,n）をΔＴ
だけ増加させる。Ｓ８でＮの場合と、Ｓ９の次に、Ｓ１
０でＴmS,nをＴ1 と比較する。このＴ1 は定数であり、
図３に示すように、吸着されたＨＣが脱離して、触媒下
流のＨＣ濃度が触媒上流のＨＣが高くなるまでの時間で
ある。この値は触媒の種類や位置に応じて設定する。Ｓ
１０でＹなら始動からまだ時間が経過していないので、
フローは終了する。Ｓ１０でＮならＳ１１に移り、Ｔ
mS,nをＴ1 かどうか判定する。Next, in S8, the output (V RO ) of the downstream O 2 sensor is compared with SL, as in S6. If Y, move to S9 and set the rich cumulative time (T mR, n ) of the downstream O 2 sensor to ΔT.
Only increase. In the case of N in S8 and after S9, S1
At 0, compare T mS, n with T 1 . This T 1 is a constant,
As shown in FIG. 3, it is the time until the adsorbed HC is desorbed and the HC concentration at the downstream side of the catalyst becomes high at the HC concentration at the upstream side of the catalyst. This value is set according to the type and position of the catalyst. S
If it is 10 at Y, it means that the time has not passed since the start.
The flow ends. If N in S10, move to S11, T
It is determined whether mS, n is T 1 .

【００２０】Ｓ１１でＹなら時間がＴ1 経過したので触
媒の最初の診断を行う。Ｓ１２ではフローチャートに示
すように、触媒の上下流でのリッチ時間の比を所定値ｋ
1 と比較する。触媒が正常なら図３に示すように、上流
Ｏ2 センサのリッチ割合は５０％位だし、下流Ｏ2 セン
サは排気中のＨＣを吸着するために、リッチ割合は小さ
い。従ってこの比は大きくなる。このｋ1 も触媒の種類
や取付位置に応じて設定する。このＳ１２でＮならＳ１
７に移って、触媒異常と判定する。Ｓ１２でＹならＳ１
３に移って、タイア（ＴmR,nとＴmF,n）を０にリセット
して後半の診断に備える。If Y in S11, the time T 1 has elapsed, so the first diagnosis of the catalyst is performed. In S12, as shown in the flowchart, the ratio of the rich times in the upstream and downstream of the catalyst is set to a predetermined value k.
Compare with 1 . If the catalyst is normal, as shown in FIG. 3, the rich ratio of the upstream O 2 sensor is about 50%, and the downstream O 2 sensor adsorbs HC in the exhaust gas, so the rich ratio is small. Therefore, this ratio becomes large. This k 1 is also set according to the type of catalyst and the mounting position. If N in S12, S1
Moving to 7, it is determined that the catalyst is abnormal. If Y in S12, S1
Moving to 3, the tires (T mR, n and T mF, n ) are reset to 0 to prepare for the latter half of the diagnosis.

【００２１】Ｓ１１でＮなら図３に示す時間Ｔ2 での脱
離条件での診断に移る。Ｓ１４ではＴmS,nをＴ2 と比較
する。ＮならまだＴ2 だけ経過していないので、フロー
を終了する。Ｓ１４でＹなら時間がＴ2 経過したので、
触媒上流と下流とのリッチ時間の比を所定値ｋ2 と比較
する。触媒が正常なら図３に示すように、かなり小さく
なる。Ｓ１５でＹならＳ１６に移って、触媒正常と判定
する。Ｓ１５でＮならＳ１７に移って、触媒異常と判定
する。If the answer in S11 is N, the process proceeds to the diagnosis under the desorption condition at the time T 2 shown in FIG. At S14, T mS, n is compared with T 2 . If it is N, T 2 has not yet elapsed, so the flow ends. If Y in S14, time T 2 has elapsed, so
The ratio of the rich times of the catalyst upstream and downstream is compared with a predetermined value k 2 . If the catalyst is normal, it will be considerably smaller, as shown in FIG. If Y in S15, the process proceeds to S16 to determine that the catalyst is normal. If NO in S15, the process proceeds to S17, and it is determined that the catalyst is abnormal.

【００２２】図４には触媒が劣化した条件における、各
信号を示す。FIG. 4 shows each signal under the condition that the catalyst is deteriorated.

【００２３】触媒のＨＣ吸着能力がないために、触媒上
下流のＯ2 センサ信号はほぼ同一である。Due to the catalyst's inability to adsorb HC, the O 2 sensor signals upstream and downstream of the catalyst are almost the same.

【００２４】ｔ3 以降は触媒のＯ2 ストレージ機能が働
くために、下流Ｏ2 センサの反転回数は減少する。After t 3, since the O 2 storage function of the catalyst works, the number of reversals of the downstream O 2 sensor decreases.

【００２５】以上のように、本実施の形態においては、
始動からＴ1 時間経過までには触媒のＨＣ吸着能力を診
断し、Ｔ1 経過後、Ｔ2 時間には触媒のＨＣ脱離能力を
診断することにより、高精度の診断を行う。As described above, in the present embodiment,
A high-accuracy diagnosis is performed by diagnosing the HC adsorption capacity of the catalyst from the start to T 1 hours and by diagnosing the HC desorption capacity of the catalyst at T 2 after T 1 has elapsed.

【００２６】〔実施の形態２〕図６に、本発明の実施の
形態２のフローチャートを示す。[Second Embodiment] FIG. 6 shows a flowchart of a second embodiment of the present invention.

【００２７】実施の形態２は、診断を行うタイミングを
機関の冷却水温によって決定するものである。実施の形
態１と異なるのは、Ｓ５Ｂで冷却水温センサの出力から
冷却水温を検出するステップである。Ｓ６〜Ｓ９は実施
の形態１と同一である。Ｓ１０ではＴw を所定値ＴW1と
比較する。Ｓ１０でＹなら冷却水温はまだ低すぎるので
終了する。Ｓ１０でＮＯならＳ１１に移ってＴW がＴW1
に等しいかどうかを判定する。Ｓ１１でＹＥＳなら前半
の診断を行うタイミングなので、Ｓ１２に移る。Ｓ１２
〜Ｓ１３は実施の形態１と同じである。In the second embodiment, the timing of diagnosis is determined by the cooling water temperature of the engine. The difference from the first embodiment is the step of detecting the cooling water temperature from the output of the cooling water temperature sensor in S5B. S6 to S9 are the same as those in the first embodiment. In S10, T w is compared with a predetermined value T W1 . If the answer is Y in S10, the cooling water temperature is still too low, and the process ends. If NO in S10, move to S11 and T W is T W1
Is determined to be equal to. If YES in S11, it is the timing for diagnosing the first half, so the process proceeds to S12. S12
S13 are the same as those in the first embodiment.

【００２８】Ｓ１１でＮならＳ１４に移る。Ｓ１４では
ＴW をＴW2と比較する。Ｓ１４でＮなら後半の診断を行
うタイミングではないので終了する。Ｓ１４でＹならＳ
１５に移る。Ｓ１５〜Ｓ１７は実施の形態１と同じであ
る。If N in S11, the process proceeds to S14. In S14, T W is compared with T W2 . If it is N in S14, it is not the timing for performing the latter half of the diagnosis, so the process ends. If Y in S14, S
Go to 15. S15 to S17 are the same as those in the first embodiment.

【００２９】図７に各信号の変化を示す。FIG. 7 shows changes in each signal.

【００３０】[0030]

【発明の効果】以上説明してきたように、本発明におい
てＨＣ吸着触媒やリーンＮＯｘ触媒のように冷間時にＨ
Ｃを吸着し、暖機後にＨＣを脱離する触媒を上下流のＯ
2 センサのリッチ時間の比から診断する方法としたた
め、吸着時と脱離時にそれぞれ診断出来るので、診断の
精度を向上することができる。As described above, in the present invention, as in the HC adsorption catalyst and the lean NOx catalyst, H
A catalyst that adsorbs C and desorbs HC after warming up
Since the method of diagnosis is based on the ratio of the rich times of the two sensors, it is possible to make a diagnosis at the time of adsorption and at the time of desorption, so the accuracy of the diagnosis can be improved.

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

【図１】本発明におけるクレーム対応図である。FIG. 1 is a diagram corresponding to a claim in the present invention.

【図２】本発明における実施の形態１を示した図であ
る。FIG. 2 is a diagram showing Embodiment 1 of the present invention.

【図３】本発明における実施の形態１の触媒が正常な場
合を示した図である。FIG. 3 is a diagram showing a case where the catalyst according to the first embodiment of the present invention is normal.

【図４】本発明における実施の形態１の触媒が劣化して
いる場合を示した図である。FIG. 4 is a diagram showing a case where the catalyst according to the first embodiment of the present invention is deteriorated.

【図５】本発明における実施の形態１のフローチャート
を示した図である。FIG. 5 is a diagram showing a flowchart according to the first embodiment of the present invention.

【図６】本発明における実施の形態２を示した図であ
る。FIG. 6 is a diagram showing a second embodiment of the present invention.

【図７】本発明における実施の形態２の各信号の変化を
示した図である。FIG. 7 is a diagram showing changes in each signal according to the second embodiment of the present invention.

【符号の説明】[Explanation of symbols]

Ａ 上流側Ｏ2 センサ Ｂ 下流側Ｏ2 センサ Ｃ 水温センサ Ｄ 信号比較回路 Ｅ 触媒劣化回路 Ｆ 警報回路 １ エンジン ２ エアフロメータ ３ スロットルバルブ ４ 吸気管 ５ インジェクタ ６ 点火プラグ ７ 排気マニホールド ８ フロントチューブ １０ 触媒 １１ マフラ １２ コントローラ １３ エアフロメータ １４ クランク角センサ １５ 冷却水温センサ １６ 上流側Ｏ2 センサ １７ 下流側Ｏ2 センサ １８ 発光ダイオードA upstream O 2 sensor B downstream O 2 sensor C water temperature sensor D signal comparison circuit E catalyst deterioration circuit F alarm circuit 1 engine 2 air flow meter 3 throttle valve 4 intake pipe 5 injector 6 spark plug 7 exhaust manifold 8 front tube 10 catalyst 11 Muffler 12 Controller 13 Air Flow Meter 14 Crank Angle Sensor 15 Cooling Water Temperature Sensor 16 Upstream O 2 Sensor 17 Downstream O 2 Sensor 18 Light Emitting Diode

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｆ０２Ｄ 41/14 ３１０ Ｆ０２Ｄ 41/14 ３１０Ｆ ３１０Ｋ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Office reference number FI Technical display location F02D 41/14 310 F02D 41/14 310F 310K

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 機関の排気管に装着された触媒の排気上
下流にＯ2 センサを装着し、ラムダコントロール条件に
おける両Ｏ2 センサの周波数比から前記触媒の劣化を診
断する触媒の自己診断装置において、 機関の始動から暖機に至る間に、前記触媒上流のＯ2 セ
ンサ出力が変化しても、下流のＯ2 センサ出力がリッチ
出力を示す事により、前記触媒の性能が良い事を診断す
ることを特徴とする触媒の自己診断装置。1. A catalyst self-diagnosis device in which an O 2 sensor is mounted upstream and downstream of a catalyst mounted in an exhaust pipe of an engine, and the deterioration of the catalyst is diagnosed from a frequency ratio of both O 2 sensors under a lambda control condition. In the above, even if the output of the O 2 sensor upstream of the catalyst changes from the start of the engine to the warm-up, the output of the downstream O 2 sensor shows a rich output, thereby diagnosing that the performance of the catalyst is good. A self-diagnosis device for a catalyst characterized by: 【請求項２】 機関の排気管に装着された触媒の排気上
下流にＯ2 センサを装着し、ラムダコントロール条件に
おける両Ｏ2 センサの周波数比から前記触媒の劣化を診
断する触媒の自己診断装置において、 機関の始動から暖機に至る間に、前記触媒上流のＯ2 セ
ンサ出力が変化しても、まず下流のＯ2 センサ出力がリ
ーン出力を示し、さらに時間が経過したら、前記触媒上
流のＯ2 センサ出力が変化しても下流のＯ2 センサ出力
がリッチ出力を示すことにより触媒の性能が良い事を診
断する特徴を有する触媒の自己診断装置。2. A catalyst self-diagnosis device in which an O 2 sensor is mounted upstream and downstream of a catalyst mounted on an exhaust pipe of an engine, and the deterioration of the catalyst is diagnosed from a frequency ratio of both O 2 sensors under a lambda control condition. in, while leading to warm up from the start of the engine, even if the O 2 sensor output is a change in the catalyst upstream, first downstream O 2 sensor output indicates a lean output, after a lapse of further time, the catalyst upstream O 2 self-diagnosis apparatus of a catalyst having the characteristics of diagnosing that catalyst performance is good by indicating the downstream O 2 sensor output rich output also the sensor output is changed. 【請求項３】 前記触媒としてＨＣ吸着触媒又はリーン
ＮＯｘ触媒とする事を特徴とする請求項１，２に記載の
触媒の自己診断装置。3. The catalyst self-diagnosis device according to claim 1, wherein the catalyst is an HC adsorption catalyst or a lean NOx catalyst. 【請求項４】 前記触媒性能の診断を、機関の始動から
冷却水温が定常値となるまでの暖機過程のみに行う事を
特徴とする請求項１，２，３に記載の触媒の自己診断装
置。4. The catalyst self-diagnosis according to claim 1, wherein the catalyst performance diagnosis is performed only during a warm-up process from engine start-up until the cooling water temperature reaches a steady value. apparatus. 【請求項５】 前記触媒の診断する性能として、ＨＣ吸
着触媒のＨＣ吸着性能、リーンＮＯｘ触媒のリーン条件
におけるＮＯｘ転化性能とする事を特徴とする請求項
１，２，３に記載の触媒の自己診断装置。5. The catalyst according to claim 1, wherein the performance of the catalyst to be diagnosed is HC adsorption performance of an HC adsorption catalyst and NOx conversion performance of a lean NOx catalyst under lean conditions. Self-diagnosis device.
JP23292795A 1995-09-11 1995-09-11 Catalyst self-diagnosis device Expired - Fee Related JP3588662B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP23292795A JP3588662B2 (en) 1995-09-11 1995-09-11 Catalyst self-diagnosis device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP23292795A JP3588662B2 (en) 1995-09-11 1995-09-11 Catalyst self-diagnosis device

Publications (2)

Publication Number Publication Date
JPH0979028A true JPH0979028A (en) 1997-03-25
JP3588662B2 JP3588662B2 (en) 2004-11-17

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ID=16947029

Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Link
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002349326A (en) * 2001-05-25 2002-12-04 Mazda Motor Corp Exhaust emissions control device for engine
US6797517B1 (en) 1999-04-28 2004-09-28 Toyota Jidosha Kabushiki Kaisha Catalyst degradation detecting device and method thereof in internal combustion engine
KR100906880B1 (en) * 2008-03-31 2009-07-08 현대자동차주식회사 Monitoring method for efficiency of catalyst in lean nox trap
US7730716B2 (en) 2005-09-08 2010-06-08 Mitsubishi Jidosha Kogyo K.K. HC adsorbing material and device for judging deterioration of the HC adsorbing material

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6797517B1 (en) 1999-04-28 2004-09-28 Toyota Jidosha Kabushiki Kaisha Catalyst degradation detecting device and method thereof in internal combustion engine
JP2002349326A (en) * 2001-05-25 2002-12-04 Mazda Motor Corp Exhaust emissions control device for engine
US7730716B2 (en) 2005-09-08 2010-06-08 Mitsubishi Jidosha Kogyo K.K. HC adsorbing material and device for judging deterioration of the HC adsorbing material
KR100906880B1 (en) * 2008-03-31 2009-07-08 현대자동차주식회사 Monitoring method for efficiency of catalyst in lean nox trap

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