EXHAUST EMISSION CONTROL APPARATUS

• Main Authors: YOSHIDA KOHEI, NOZAKI YUSUKE, HABA YUKI
• Format: Patent
• Language: English; Japanese
• Published: 27.10.2016
• 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; STEAM ENGINES; WEAPONS

PROBLEM TO BE SOLVED: To suppress an amount of NOx emitted from a catalyst when a rich spike operation is started even in a state where an amount of NOx storage to the catalyst is large.SOLUTION: Provided is an exhaust emission control apparatus having a NOx storage-reduction type catalyst (NSR catalyst, etc.) provided in an exhaust system of an internal combustion engine and executing a rich spike operation if an amount of NOx storage to the catalyst exceeds a first threshold, and configured such that if the amount of NOx storage to the catalyst exceeds a second threshold M2 greater than the first threshold M1, the exhaust emission control apparatus starts the rich spike operation at a lean exhaust air-fuel ratio, compared with a case where the amount of NOx storage is equal to or smaller than the second threshold M2. With this configuration, it is possible to suppress an emission amount of NOx emitted from the catalyst and reduce a discharge amount of untreated NOx, so that it is possible to suppress the degradation of exhaust emission.SELECTED DRAWING: Figure 4 【課題】触媒へのＮＯｘ吸蔵量が多い状態にあっても、リッチスパイク運転を開始したときに触媒から放出されるＮＯｘの量を抑制する。【解決手段】内燃機関の排気系に設けられたＮＯｘ吸蔵還元型の触媒（ＮＳＲ触媒等）を有し、触媒へのＮＯｘ吸蔵量が第１閾値を超える場合にリッチスパイク運転を実行する排気浄化制御装置において、触媒へのＮＯｘ吸蔵量が第１閾値Ｍ１よりも大きい第２閾値Ｍ２を超える場合は、ＮＯｘ吸蔵量が第２閾値Ｍ２以下にある場合よりもリーン側の排気空燃比でリッチスパイク運転を開始する。このような構成により、触媒から放出されるＮＯｘの放出量を抑えることができ、未処理ＮＯｘの流出量を減らすことができる結果、排気エミッションの悪化を抑制することができる。【選択図】図４