EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of suppressing deterioration of emission control performance by eliminating an HC component adhered to an oxidation catalyst.SOLUTION: An exhaust emission control device includes an oxidation catalyst 10 and a filter 20. The exhaust emission control device further includes: a first branch passage 5 branched from an exhaust passage upstream of the filter and connected to one side of the oxidation catalyst; a second branch passage 7 connected to the other side of the oxidation catalyst; an exhaust change-over valve 30 provided in the exhaust passage and enabling switching between a first flow for causing exhaust gas to flow from one side of the oxidation catalyst and a second flow for causing the exhaust gas from the other side of the oxidation catalyst; fuel injection means capable of executing post injection for adding fuel into the exhaust gas upstream of the oxidation catalyst; oxidation catalyst state detection means for determining abnormal occlusion of the oxidation catalyst; and a control section for when determining that the oxidation catalyst is in the abnormal occlusion state based on the detection, switching the exhaust change-over valve to reverse the flow of the exhaust gas flowing in the oxidation catalyst and raising a catalyst temperature by performing post injection to the upstream side of the oxidation catalyst.SELECTED DRAWING: Figure 1 【課題】酸化触媒に付着するＨＣ成分を除いて浄化性能の低下を抑制可能な内燃機関の排気浄化装置を提供する。【解決手段】排気浄化装置は、酸化触媒１０とフィルタ２０を有し、フィルタの上流で排気通路から分岐して酸化触媒の一方側に接続される第１分岐通路５と、酸化触媒の他方側に接続される第２分岐通路７と、排気通路に設けられ、酸化触媒の一方側から排気ガスを流す第１流れと酸化触媒の他方側から排気ガスを流す第２流れを切換え可能な排気切換弁３０と、酸化触媒の上流において排気ガス中に燃料を添加するポスト噴射を実施可能な燃料噴射手段と、酸化触媒の異常閉塞を判断するための酸化触媒状態検出手段と、この検出から酸化触媒が異常閉塞の状態にあると判断すると、排気切換弁を切換えて酸化触媒を流れる排気ガスの流れを逆転させるとともに、酸化触媒の上流にポスト噴射を行って触媒温度を昇温させる制御部とを、備える。【選択図】図１