CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine accurately diagnosing deterioration of a NOx catalyst and ensuring many opportunities for diagnosis in a system equipped with a device for varying a cooling rate of exhaust gas and to accurately diagnose the failure of a control valve equipped on the device for varying the cooling rate of exhaust gas with a simple configuration.

SOLUTION: Temperature of the NOx catalyst 22 is controlled to fall within a predetermined temperature range by controlling a ratio of an amount of exhaust gas flowing through a first passage 14 and an amount of exhaust gas flowing through a second passage 16 installed with a cooling device 20 by the control valve 18. In a state in which the temperature of the NOx catalyst 22 falls within the predetermined temperature range, the deterioration of the NOx catalyst is diagnosed. A retard time in exhaust gas transportation from the internal combustion engine 10 to the NOx catalyst 22 is measured and thereby the failure of the control valve 18 is diagnosed.

COPYRIGHT: (C)2008,JPO&INPIT