Patent ID: 7159391
Filing Date: 2007-01-09
Classification: F01N,F02D

Abstract:
1. A method for restricting an excessive temperature rise of a filter in an internal combustion engine, the internal combustion engine having a filter provided in an exhaust passage for collecting particulate matter contained in exhaust gas, wherein when the amount of particulate matter depositing on the filter becomes equal to or larger than a specified deposition amount, the temperature of the filter is raised to oxidize and remove the particulate matter depositing on the filter, the method comprising: a first step of decreasing, when a condition with which it is anticipated that the temperature of said filter will become equal to or higher than a specified temperature is established while the removal of particulate matter from said filter is performed, the oxygen concentration in exhaust gas flowing into said filter; and a second step of gradually increasing, when said condition expires after the first step, the oxygen concentration in the exhaust gas flowing into said filter; wherein the establishment of said condition corresponds to the time when the running state of said internal combustion engine becomes idle running, and the expiration of said condition corresponds to the time when the running state of said internal combustion engine becomes a running state with an engine load higher than in the idle running.