Abnormality determination system for an exhaust device

An abnormality determination system for an exhaust device which is applied to the exhaust device including a particulate filter that is disposed in an exhaust passage of an internal combustion engine for trapping particulate matter in exhaust gas, and a differential pressure obtaining device configured to obtain an actual differential pressure which is an actual difference between a pressure of the exhaust gas at an upstream side of said particulate filter and an atmospheric pressure, wherein said abnormality determination system is to determine an abnormality of said exhaust device,

• said system comprising;
• a controller comprising at least one processor configured to;
• detect a flow rate of the exhaust gas passing through said particulate filter;
• estimate, based on a first actual differential pressure which is an actual differential pressure obtained by said differential pressure obtaining device and a first flow rate of the exhaust gas which is a flow rate of the exhaust gas detected at a time when said first actual differential pressure is obtained, a differential pressure between a pressure of the exhaust gas at the upstream side of said particulate filter and an atmospheric pressure in a case where the flow rate of the exhaust gas passing through said particulate filter is a second flow rate of the exhaust gas different from said first flow rate of the exhaust gas;
• and
• determine that an exhaust system component disposed at a downstream side of said particulate filter is abnormal, in cases where a difference between the estimated differential pressure and a second actual differential pressure, which is an actual differential pressure obtained at a time when the detected flow rate of the exhaust gas is equal to said second flow rate of the exhaust gas, is equal to or more than a predetermined threshold value.