| abstract |
In an internal combustion engine, a hydrocarbon supply valve (15), a NO x storage catalyst (13), a particulate filter (14), and an electric resistance sensor (29) are arranged in the engine exhaust passage in order from the upstream side. Be placed. When the particulate matter and hydrocarbons contained in the exhaust gas adhere to the sensor unit, the electrical resistance sensor (29) generates an output value corresponding to the amount of particulate matter and hydrocarbons attached. From the change in the output value of the electrical resistance sensor (29), it is determined whether hydrocarbons have passed through the NO x storage catalyst (13) and whether particulate matter has passed through the particulate filter (14). The |