| 摘要 |
<p>An object of the present invention is to determine, more appropriately, whether or not there is a malfunction in a reducing agent supply apparatus having a reducing agent addition valve provided in the exhaust system of an internal combustion engine. According to the present invention, the reducing agent addition valve injects liquid reducing agent into the exhaust gas. Temperature sensing means for sensing the temperature of the exhaust gas is provided at a position in the exhaust system of the internal combustion engine through which the reducing agent injected through the reducing agent addition valve passes. As the reducing agent is injected through the reducing agent addition valve, the temperature decrease of the exhaust gas at the position through which the reducing agent passes is calculated by temperature decrease calculation means. Whether or not there is a malfunction in the reducing agent supply apparatus is determined by diagnosis means, based on the temperature decrease of the exhaust gas.</p> |
