CATALYST DETERIORATION DIAGNOSIS METHOD AND CATALYST DETERIORATION DIAGNOSIS SYSTEM

To provide a catalyst deterioration diagnosis method capable of highly accurately performing catalyst deterioration diagnosis on the basis of an NOx concentration in an exhaust gas after passing a catalyst.SOLUTION: A catalyst deterioration diagnosis method is provided for a system including a gas s...

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Bibliographic Details
Main Authors OKAMOTO TAKU, MONNA KOSUKE, NAKASONE OSAMU
Format Patent
LanguageEnglish
Japanese
Published 19.03.2020
Subjects
BLASTING
COMBUSTION ENGINES
CONTROLLING COMBUSTION ENGINES
ENGINE PLANTS IN GENERAL
GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNALCOMBUSTION ENGINES
GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES ORENGINES IN GENERAL
HEATING
HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
LIGHTING
MACHINES OR ENGINES IN GENERAL
MECHANICAL ENGINEERING
PERFORMING OPERATIONS
PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
SEPARATION
STEAM ENGINES
TRANSPORTING
WEAPONS
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Summary:To provide a catalyst deterioration diagnosis method capable of highly accurately performing catalyst deterioration diagnosis on the basis of an NOx concentration in an exhaust gas after passing a catalyst.SOLUTION: A catalyst deterioration diagnosis method is provided for a system including a gas sensor 702 configured to measure an air-fuel ratio and a nitrogen oxide concentration of an exhaust gas after passing a catalyst 601, and having ammonium coherency. When a fuel injection device 501 restarts fuel injection after fuel cut in a case that a latest air-fuel ratio obtained by the gas sensor 702 is greater than a predetermined threshold air-fuel ratio that is greater than a theoretical air-fuel ratio, monitoring of temporary increase in the nitrogen oxide concentration detected by the gas sensor 702 is started, thereby obtaining a temporary increase amount of the nitrogen oxide concentration. It is determined whether the temporary increase amount is greater than a threshold amount.SELECTED DRAWING: Figure 1 【課題】触媒通過後の排ガス中のＮＯｘ濃度に基づいての触媒劣化診断を高精度で行うことができる触媒劣化診断方法を提供する。【解決手段】触媒劣化診断方法は、触媒６０１を通過した排ガスの空燃比および窒素酸化物濃度を測定するものであってアンモニア干渉性を有するガスセンサ７０２を含むシステムのためのものである。ガスセンサ７０２によって最新で得られている空燃比が、理論空燃比よりも大きな予め定められたしきい空燃比よりも大きい場合において、燃料噴射装置５０１が燃料カット後に燃料噴射を再開するときに、ガスセンサ７０２によって検出される窒素酸化物濃度の一時的増大をモニタし始めることによって、窒素酸化物濃度の一時的増大量が取得される。一時的増大量がしきい量よりも大きいか否かが判定される。【選択図】図１
Bibliography:Application Number: JP20180167736