Metering system and method for operating a metering system
AssigneeRobert Bosch GmbH
InventorsWolfgang Ripper, Markus Buerglin, Thorsten Mayer, Michael Offenhuber, Dirk Heilig
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Abstract
The invention relates to a dosing system comprising a dosing means for metering a liquid, especially an aqueous urea solution used for the after treatment of exhaust gases generated by combustion engines. The liquid can be conveyed from a reservoir into an exhaust manifold through the dosing means in a normally operating conveying device. According to the invention, at least one area that is located between a dosing point and the reservoir and is impinged upon by the liquid can be emptied counter to a normal transport direction of the liquid.
Claims18
A metering system having a metering means for metering an aqueous urea solution for posttreatment of exhaust gases from internal combustion engines, the metering means comprising a pump for feeding the solution from a tank in a normal-operation feeding direction into an exhaust manifold at a metering point, and at least one region, acted upon by the liquid, between the metering point and the pump, the at least one region being capable of being emptied of the solution in an opposite direction from the normal-operation feeding direction of the solution, the conveying direction of the pump being reversible, so that, with the conveying direction reversed, the at least one region can be emptied, and a suction intake of a gas takes place in a region of the metering point.
A method for operating a metering system having a metering means for metering an aqueous urea solution for posttreatment of exhaust gases from internal combustion engines, the metering means comprising a pump for feeding the solution from a tank in a normal-operation feeding direction into an exhaust manifold at a metering point, and at least one region, acted upon by the liquid, between the metering point and the pump, the method comprising the step of reversing the conveying direction of the pump to induce a gas flow in the at least one region in a direction opposite to the normal-operation feeding direction, so that, with the conveying direction reversed, the at least one region can be emptied of the solution and a suction intake of a gas takes place in the region of the metering point.
Dependencies are inferred from the claim text.