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AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsHIROFUMI OHUCHI, SATOSHI WACHI, HIDEAKI KATASHIBA, TOSIAKI YONEKURA
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In order to suppress the quantity of the nitrogen oxide to be released to the atmosphere when the operation state is shifted from the engine operation with lean air fuel ratio to that with stoichiometric air fuel ratio, the exhaust gas purification apparatus is arranged such that by means of the forced rich operation means, when the operation state is shifted from the engine operation with lean air fuel ratio to that with stoichiometric air fuel ratio, the operation state is shifted to the engine operation with stoichiometric air fuel ratio after performing that with rich air fuel ratio.
An exhaust gas purification apparatus for an internal combustion engine comprising a NOx catalyst arranged in an exhaust gas passage of said internal combustion engine and an air fuel ratio control means in which one of operations among an engine operation with lean air fuel ratio, that with stoichiometric air fuel ratio and that with rich air fuel ratio is selected depending on an engine operation state, wherein said air fuel ratio control means comprises a means for forced engine operation with rich air fuel ratio for shifting the engine operation to said engine operation with stoichiometric air fuel ratio after performing said engine operation with rich air fuel ratio when said engine operation state is shifted from said engine operation with lean air fuel ratio to said engine operation with stoichiometric air fuel ratio.
An exhaust gas purification apparatus for an internal combustion engine comprising a NOx catalyst arranged in an exhaust gas passage of said internal combustion engine and an air fuel ratio control means in which one of operations among an engine operation with lean air fuel ratio, that with stoichiometric air fuel ratio and that with rich air fuel ratio is selected depending on an engine operation state, wherein said air fuel ratio control means comprises an additional fuel injection means for performing an additional fuel injection during an expansion stroke or an exhaust stroke when the operation state is shifted from said engine operation with lean air fuel ratio to said engine operation with stoichiometric air fuel ratio.
An exhaust gas purification apparatus for an internal combustion engine comprising a NOx catalyst arranged in an exhaust gas passage of said internal combustion engine and an air fuel ratio control means in which one of operations among an engine operation with lean air fuel ratio, that with stoichiometric air fuel ratio and that with rich air fuel ratio is selected depending on an engine operation state, wherein said air fuel ratio control means comprises a means for performing an additional fuel injection, when the engine operation state is shifted from said engine operation with lean air fuel ratio to that with stoichiometric air fuel ratio, at first shifting the engine operation state to said engine operation with stoichiometric air fuel ratio after performing said engine operation with rich air fuel ratio and for performing thereafter an additional fuel injection during an expansion stroke or an exhaust stroke.
Dependencies are inferred from the claim text.