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(11) | EP 1 054 149 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Controller of internal combustion engine |
(57) An internal combustion engine has a reduction occlusion type NOx catalyst located
in an exhaust passage for adsorbing NOx. A controller of the engine temporarily discontinues
a lean combustion mode when a predetermined condition is satisfied during the lean
combustion mode. When the amount of NOx adsorbed in the catalyst is greater than an
acceptable value, the controller executes a rich-spike control procedure to reduce
NOx adsorbed in the catalyst by temporarily switching the combustion mode of the engine
to a rich combustion mode. The controller determines whether the amount of NOx adsorbed
in the catalyst is greater than a predetermined determination value, which is smaller
than the acceptable value, when lean combustion is discontinued. When the amount of
NOx adsorbed in the catalyst is determined to be greater than the determination value,
the controller executes rich-spike control procedure. |