Exhaust gas after-treatment system for e.g. diesel engine of motor vehicle, has injection device provided upstream to catalyzer and formed as electromagnetically operated piston pump valve unit

摘要

The system (1) has a catalyzer (5) arranged in an exhaust duct (2) of an internal combustion engine, where an injection device (9) for a fluid exhaust gas after-treatment agent is provided upstream to the catalyzer. The injection device is formed as an electromagnetically operated piston pump valve unit (10). The valve unit has a pump piston axially displaceable in a cylinder, and return valves are attached to an inflow opening and/or an injection opening of the cylinder. The injection opening is formed in a front side of the cylinder.