Method and device for exhaust gas after-treatment in an internal combustion engine equipped with an SCR catalyst
AssigneeSiemens Akteingesellschaft
InventorManfred Weigl
Life of this patent
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Abstract
An internal combustion engine operated with excess air has an exhaust gas after-treatment device wherein nitrogen oxides in the exhaust gas are reduced by selective catalytic reduction. A pump is connected between a reducing agent container and a metering device for controlled feeding of a reducing agent to the exhaust gas upstream of an SCR catalyst. A pressure accumulator with an associated pressure sensor for intermediately storing the reducing agent is connected between the pump and the metering device. The pump delivers only so much reducing agent into the pressure accumulator as is being used in the exhaust gas after-treatment.
Claims14
A method of after-treating exhaust gas of an internal combustion engine operating with excess air, wherein nitrogen oxides in the exhaust gas are reduced by selective catalytic reduction, which comprises:
- pumping a liquid reducing agent from a reducing agent container into a pressure accumulator;
- delivering, during specific operating states of an internal combustion engine, quantities of the reducing agent to an exhaust gas of the internal combustion engine upstream of an SCR catalyst, by opening a metering device and taking a quantity of reducing agent currently required for exhaust gas after-treatment from the pressure accumulator;
- and
- wherein the pumping step comprises delivering only a quantity of the reducing agent required by the metering to the pressure accumulator.
An exhaust gas after-treatment device for an internal combustion engine operating with excess air, wherein nitrogen oxides in the exhaust gas are reduced by selective catalytic reduction, comprising:
- a reducing agent container;
- a metering device for controlled feeding of a reducing agent to an exhaust gas of an internal combustion engine upstream of an SCR catalyst in an exhaust gas flow direction;
- a pump communicating with said reducing agent container for pumping reducing agent from said reducing agent container;
- and
- a pressure accumulator in form of a flexible line connected between said pump and said metering device for intermediately storing the reducing agent, and a pressure sensor operatively associated with said pressure accumulator.
Dependencies are inferred from the claim text.