Filter failure diagnostic device for an internal combustion engine

A filter failure diagnostic device for an internal combustion engine for performing a failure diagnostics for a filter which collects particulate matter contained in an exhaust gas of the internal combustion engine capable of using gaseous fuel and liquid fuel, the filter failure diagnostic device for the internal combustion engine comprising:

• a PM amount detecting sensor which is provided on a downstream side of the filter in an exhaust gas passage of the internal combustion engine and which detects an added-up amount of the particulate matter contained in the exhaust gas allowed to pass through a portion downstream from the filter;
• and
• a controller, comprising at least one processor, configured to:
• estimate an added-up amount of the particulate matter contained in the exhaust gas allowed to pass through the portion downstream from the filter in the exhaust gas passage on the basis of a fuel injection amount and a predetermined parameter;
• and
• judge any failure of the filter in accordance with the added-up amount of the particulate matter contained in the exhaust gas allowed to pass through the portion downstream from the filter as detected by the PM amount detecting sensor during a predetermined period and the added-up amount of the particulate matter contained in the exhaust gas allowed to pass through the portion downstream from the filter as estimated during the predetermined period, and
• wherein the controller is further configured to estimate the added-up amount of the particulate matter contained in the exhaust gas allowed to pass through the portion downstream from the filter in the exhaust gas passage on the basis of the predetermined parameter and only a fuel injection amount of the liquid fuel out of a fuel injection amount of the gaseous fuel and the fuel injection amount of the liquid fuel.