| 摘要 |
An additive supply system comprises an addition valve (6) for injecting an additive into a catalyst (8), a main channel (2) for supplying additive in a tank (1) to the addition valve (6), a pump (4) provided in the main channel (2), a return channel (3) connected to the tank (1) and branching from the main channel (2), and a check valve (5) which prevents the additive from flowing from the return channel (3) to the main channel (2) and opens when the pressure in the main channel (2) is equal to or greater than a prescribed valve opening pressure. An electronic control device (10) performs draw-back control for drawing additive in the main channel (2) back into the tank (2) by running the pump (4) in reverse. Moreover, the electronic control device (10) runs the pump (4) in forward with the addition valve (6) closed when performing fill control for filling the main channel (2) with additive after draw back control has been performed, and then opens the addition valve (6) and runs the pump (4) in forward. |
