SCR system and a method of purging it

摘要

There is provided a system for storing and injecting an additive into exhaust gas from an internal combustion engine, the system comprising a tank for storing the additive, an injector, and a pump for driving the additive from the tank to the injector via an injection channel, the system also comprising a purge device mounted between the pump and the injection channel. The purge device comprises a chamber and piston moving equipment slidably mounted in the chamber, the purge device being designed so that:
movement of the moving equipment in one of its sliding directions causes a passage to open into the chamber for passing the additive to the injection channel; andmovement of the moving equipment in its other sliding direction creates suction within the chamber, which causes at least some of the additive contained in the injection channel to return into the chamber.

主权项

1. A system, comprising:
a tank for storing an additive, an injector, and a pump for driving the additive from the tank to the injector via an injection channel; and a passive purge device which operates without any electrical power supply or any control signal from a computer or a control unit, and which is mounted between the pump and the injection channel; wherein: the passive purge device comprises a chamber and piston moving equipment slidably mounted in the chamber; the passive purge device is adapted to function such that
movement of the piston moving equipment in a first sliding direction causes a passage to open into the chamber for passing the additive to the injection channel, andmovement of the piston moving equipment in a second sliding direction creates suction within the chamber, which causes at least some of the additive contained in the injection channel to return into the chamber, such that the movement of the piston moving equipment in the second sliding direction closes the passage; and the system is adapted for storing and injecting the additive into exhaust gas from an internal combustion engine.