To provide a deterioration diagnostic device for an engine exhaust system capable of suppressing deterioration of an exhaust gas component due to a deterioration determination of an air-fuel ratio sensor and a catalyst.SOLUTION: A control unit 16 of a deterioration diagnostic device for an engine exhaust system includes: a time measurement section 32 measuring a first elapsed time from when a measurement value of an air-fuel ratio sensor 27 becomes below a predetermined first threshold value to when the measurement value becomes below a second threshold value on a lean side after a target air-fuel ratio is shifted to a lean region; a sensor deterioration determination section 34 determining deterioration of the air-fuel ratio sensor 27 on the basis of the first elapsed time; an integration section 33 determining integrated oxygen amount obtained by integrating oxygen amount occluded in a catalyst 25 before the measurement value obtained by the air-fuel ratio sensor 27 becomes below a predetermined third threshold value on the lean side of the second threshold value after the target air-fuel ratio is shifted to the lean region or a parameter corresponding to the integrated oxygen amount; and a catalyst deterioration determination section 35 determining deterioration of the catalyst 25 on the basis of the integrated oxygen amount or the parameter corresponding to the integrated oxygen amount.SELECTED DRAWING: Figure 2

    【課題】空燃比センサおよび触媒の劣化判定に伴う排気ガス成分の悪化を抑制することが可能なエンジン排気系の劣化診断装置を提供する。【解決手段】エンジン排気系の劣化診断装置の制御ユニット16は、目標空燃比のリーンへの移行後に、空燃比センサ27の測定値が所定の第1閾値を下回ってからリーン側の第2閾値を下回るまでの第1経過時間を計測する時間計測部32と、第1経過時間に基づいて空燃比センサ27の劣化を判定するセンサ劣化判定部34と、目標空燃比のリーンへの移行後に空燃比センサ27の測定値が第2閾値よりもリーン側の所定の第3閾値を下回るまでに触媒25に吸蔵された酸素量を積算した積算酸素量または前記積算酸素量に対応するパラメータを求める積算部33と、積算酸素量または前記積算酸素量に対応するパラメータに基づいて触媒25の劣化を判定する触媒劣化判定部35とを備えている。【選択図】図2


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    Title :

    DETERIORATION DIAGNOSTIC DEVICE FOR ENGINE EXHAUST SYSTEM AND DETERIORATION DIAGNOSTIC METHOD FOR ENGINE EXHAUST SYSTEM


    Additional title:

    エンジン排気系の劣化診断装置、およびエンジン排気系の劣化診断方法


    Contributors:
    ITAI MITSUO (author) / OKUBO HIROSHI (author) / ATSUMI SHINJI (author)

    Publication date :

    2023-02-07


    Type of media :

    Patent


    Type of material :

    Electronic Resource


    Language :

    Japanese


    Classification :

    IPC:    F01N GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL , Schalldämpfer oder Auspuffvorrichtungen für Gase von Kraft- und Arbeitsmaschinen oder von Kraftmaschinen allgemein / B60K Anordnung oder Einbau von Antriebseinheiten oder von Kraft- bzw. Drehmomentübertragungen in Fahrzeugen , ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES / B60W CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION , Gemeinsame Steuerung oder Regelung von Fahrzeug-Unteraggregaten verschiedenen Typs oder verschiedener Funktion / F02D CONTROLLING COMBUSTION ENGINES , Steuern oder Regeln von Brennkraftmaschinen



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