| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a reducing agent supplying device capable of preventing the thermal damage to a reducer injection valve and crystallization of urea solution due to excessive cooling of liquid reducing agent, and a controlling method thereof. <P>SOLUTION: The reducing agent supplying device injects urea solution to an exhaust upstream side of reducing catalyst arranged in an exhaust passage of an internal combustion engine as the reducing agent, is used for an exhaust emission control device reducing/purifying nitrogen oxide in exhaust gas by the reducing catalyst, and equipped with a reducing agent injection valve fixed to an exhaust pipe on an exhaust upstream side of the reducing catalyst. The reducing agent supplying device comprises a cooling water circulating passage for circulating at least a part of cooling water in the internal combustion engine for cooling the reducing agent injection valve, a flow rate controlling means for adjusting the flow rate of the cooling water flowing in the cooling water circulating passage, a temperature detecting means for detecting the temperature of the reducing agent injection valve, and a controlling means for controlling the flow rate controlling means on the basis of the temperature of the reducing agent injection valve. <P>COPYRIGHT: (C)2009,JPO&INPIT |
