Exhaust purifying device for internal combustion engine

Abstract

Abstract PURPOSE:To prevent the intrusion of the exhaust rich in air-fuel ratio into a lean NOx catalyst, by installing an estimating means which stimates an air- fuel ratio rich state from the output of an operation state detecting means and opens a bypass passage. CONSTITUTION:An air-fuel ratio adjusting means 12 adjusts the air-fuel ratio by the output of an operation state detecting means 10. A lean NOx catalyst 4 is installed in the exhaust system of an internal combustion engine 2, and consists of the zeolite loading the transition metals or precious metals, and reduces the NOx in the exhaust gas under the presence of HC in the oxidation environment. In this case, an estimating means 14 for estimating the air-fuel ratio rich state from the output of the operation state detecting means 10 is installed, a bypass valve 8 is controlled so that a bypass passage 6 for bypassing the catalyst 4 is opened, when the air-fuel ratio rich state is estimated. Accordingly, even if a certain time is necessary for setting the bypass valve 8 from a closed state to an opened state, the bypass valve 8 is put into opened state when the air-fuel ratio becomes rich, and the intrusion of the exhaust rich in air-fuel ratio into the catalyst 4 is prevented.

Inventors

• 👤 Kenji Kato
• 👤 健治 加藤
• 👤 Tokuta Inoue
• 👤 井上　悳太
• 👤 Kiyoshi Obata
• 👤 小端　喜代志
• 👤 Toshiaki Tanaka
• 👤 俊明 田中
• 👤 Shinichi Takeshima
• 👤 伸一 竹島

Bibliographic Details