| 摘要 |
A liquid additive agent added into an exhaust gas is suppressed from adhering to a sensor. Provision is made for a sensor that is arranged in an exhaust passage of an internal combustion engine; an addition valve that is arranged in the vicinity of or at the downstream side of the sensor in the direction of flow of the exhaust gas, and adds an additive agent into the exhaust passage; a catalyst that is arranged at the downstream side of the addition valve, and receives a supply of the additive agent from the addition valve; and pressure difference generation means that makes a pressure of the exhaust gas in the surrounding of the sensor higher than a pressure thereof in the surrounding of the addition valve. A pressure difference is caused to generate so that the additive agent is suppressed from flowing toward the direction of the sensor. |
