| 摘要 |
A reducing agent supply device (4) equipped with: a tank (50) that stores a reducing agent; a pressure feeding means that pressure-feeds the reducing agent; a reducing agent supply passage (70) through which the reducing agent is supplied; an injection nozzle (60) that injects the reducing agent into an exhaust pipe (11); a draw-back means that draws the reducing agent back toward the tank (50); and a control device (5). After an engine (10) has stopped, the control device (5) executes a reducing agent draw-back process, wherein the reducing agent is drawn back toward the tank (50) and exhaust gas is introduced into the reducing agent supply passage (70) from the injection nozzle (60), and a gas discharge process, wherein the reducing agent is supplied and the compressed exhaust gas in the reducing agent supply passage (70) is discharged from the injection nozzle (60), and the injection nozzle (60) is closed before the reducing agent reaches the injection nozzle. |
