Patent ID: 8359827

Claim:
An abnormality diagnosis system for a filter regeneration system for executing a regeneration process of a particulate filter placed in an exhaust passage of an internal combustion engine, wherein the filter regeneration system comprises: an accumulation amount estimation unit for estimating an accumulation amount of particulate matter at the particulate filter; a pressure determination unit for determining a pressure upstream of the particulate filter in the exhaust passage or a differential pressure across the particulate filter; and an execution unit for the regeneration process for executing the regeneration process to oxidize and remove the particulate matter accumulated at the particulate filter; and initiates execution of the regeneration process by the execution unit for the regeneration process, in case the accumulation amount of the particulate matter estimated by the accumulation amount estimation unit reaches a pre-determined regeneration requiring accumulation amount; or in case the pressure or the differential pressure determined by the pressure determination unit reaches a pre-determined regeneration requiring value, the value being larger than the pressure or the differential pressure corresponding to the regeneration requiring accumulation amount, wherein the abnormality diagnosis system for the filter regeneration system comprises: a parameter calculation unit for calculating a ratio of: an accumulation amount of the particulate matter at the initiation of the execution of the regeneration process estimated by the accumulation amount estimation unit to the regeneration requiring accumulation amount; as a parameter for execution frequency of regeneration; and a diagnosis unit for diagnosing based on the parameter for execution frequency of regeneration whether or not abnormality is occurring in the filter regeneration system causing excessive execution frequency of the regeneration process.