| 摘要 |
To provide a reducing agent supply apparatus that makes it hard to refill the pump side with a liquid reducing agent upon completion of the suck back control of the liquid reducing agent and a method for control the reducing agent supply apparatus. The method for controlling the reducing agent supply apparatus pressure-feeds the liquid reducing agent in a storage tank using a pump and injects the liquid reducing agent into an exhaust passage of the internal combustion engine through a reducing agent injection valve when the internal combustion engine is operating and, when the internal combustion engine stops, sucks the liquid reducing agent remaining in a reducing agent supply path back to the storage tank, in which the suck back control starts when the internal combustion engine stops and, when the suck back control ends, a reducing agent passage interconnecting the pump and the storage tank is opened to air. |
