Exhaust Gas After Treatment System

Abstract

The invention relates to an exhaust gas aftertreatment system for delivering a reducing agent ( 15 ) into the exhaust gas stream of an internal combustion engine for selective catalytic reduction, the system having a reducing agent tank ( 1 ) and a pump ( 3 ) for delivering the reducing agent from the tank ( 1 ) to an injection unit, the tank ( 1 ) having at least one opening, the pump ( 3 ) being made as an integrated unit ( 2 ) and being plugged into the opening of the tank, the integrated unit ( 2 ) forming a tank closure and sealing the tank.

1 . An exhaust gas after treatment system for delivering a reducing agent into the exhaust gas stream of an internal combustion engine for selective catalytic reduction, the system comprising a reducing agent tank, an injection unit and a pump for delivering the reducing agent from the said reducing agent tank to said injection unit, characterized in that said reducing agent tank has at least one opening, the pump being made as an integrated unit and being plugged into the opening of the tank, the integrated unit forming a tank closure and sealing said tank, wherein the injection unit comprises at least one nozzle by which the reducing agent is injected into the exhaust gas stream and/or is atomized in the exhaust gas stream, wherein compressed air is used for atomization in order to form a uniform, finely distributed aerosol. 
     
     
         2 . The exhaust gas after treatment system as claimed in  claim 1 , wherein the integrated unit is screwed into a thread in the opening of said tank, forming a seal or wherein the unit is inserted into the opening of the tank by means of a quarter-turn fastener, forming a seal. 
     
     
         3 . The exhaust gas after treatment system as claimed in  claim 1  wherein the at least one opening is located at or near the bottom and/or in the lower region of  said tank and the unit ( 2 ) seals said tank at said at least one opening. 
     
     
         4 . The exhaust gas after treatment system as claimed in  claim 1  wherein the system at least on member selected from the group consisting of reducing agent filters filter and/or a heating apparatuses for heating of the reducing agent, temperature sensors for detecting the reducing agent temperature, power electronics for triggering the pump and/ communications interfaces, especially a standardized communications interface, including a CAN bus interface. 
     
     
         5 . The exhaust gas after treatment system as claimed in  claim 1  wherein the pump as an integrated unit has at least one member selected from the group consisting of reducing agent filters heating apparatuses for heating of the reducing agent, temperature sensors for detecting the reducing agent temperature, power electronics for triggering the pump and communication interfaces, especially CAN bus interfaces. 
     
     
         6 . The exhaust gas after treatment system as claimed in  claim 1  wherein the pump as an integrated unit has a sensor for detecting a physical property of the reducing agent, especially for detection of the electrical conductivity and/or for detection of the speed of sound in the reducing agent. 
     
     
         7 . The exhaust gas after treatment system as claimed in  claim 6 , wherein the sensor for detecting a physical property of the reducing agent is arranged in the tank such that the signal of the sensor can be used at the same time as a liquid level indicator for ascertaining that a minimum level in the tank has not been reached. 
     
     
         8 . The exhaust gas after treatment system as claimed in  claim 1  wherein the system has a control device by means of which the pump is triggered depending on the measured values acquired by the sensors and/or depending on the current operating parameters of the internal combustion engine, in particular is triggered via a bus system. 
     
     
         9 . The exhaust gas after treatment system as claimed in  claim 1  wherein there is at least one seal, especially an O-ring seal between the unit and the tank. 
     
     
         10 . The exhaust gas after treatment system as claimed in  claim 1  wherein the system has an injection unit with at least one nozzle by which the reducing agent is injected into the exhaust gas stream and/or is atomized in the exhaust gas stream. 
     
     
         11 . The exhaust gas after treatment system as claimed in  claim 2  wherein the system has an SCR catalytic converter in which the reducing agent is delivered into the exhaust gas stream of the internal combustion engine for selective catalytic reduction, upstream and/or downstream of the SCR catalytic converter there being a sensor for detecting the nitrogen oxide concentration in the exhaust gas. 
     
     
         12 . The exhaust gas after treatment system as claimed in  claim 2  wherein the integrated unit is screwed into a thread in the opening of the reducing agent tank forming a seal or wherein the integrated unit is inserted into the opening of the reducing agent tank by means of a quarter-turn fastener, forming a seal. 
     
     
         13 . The exhaust gas after treatment system as claimed in  claim 2  wherein the at least one opening is located on the bottom and/or in the lower region of the reducing agent tank and the integrated unit seals the reducing agent tank at said at least one opening. 
     
     
         14 . The exhaust gas after treatment system as claimed in  claim 2  wherein the system has at least one member selected from the group consisting of reducing agent filters, heating apparatuses for heating of the reducing agent, temperature sensors for detecting the reducing agent temperature, power electronics for triggering the pump and communications interfaces, especially a standardized communications interface, particularly a CAN bus interface. 
     
     
         15 . The exhaust gas after treatment system as claimed in  claim 2  wherein the pump as an integrated unit has at least one member selected from the group consisting of reducing agent filters, heating apparatuses for heating of the reducing agent, temperature sensors for detecting the reducing agent temperature, power electronics for triggering the pump and interfaces, especially a CAN bus interface. 
     
     
         16 . The exhaust gas after treatment system as claimed in  claim 2  wherein the pump is an integrated unit having a sensor for detecting a physical property of the reducing agent, especially for detection of the electrical conductivity and/or for detection of the speed of sound in the reducing agent. 
     
     
         17 . The exhaust gas after treatment system as claimed in  claim 16 , wherein the sensor for detecting a physical property of the reducing agent is arranged in the reducing agent tank such that the signal of the sensor can be used at the same time as a liquid level indicator for ascertaining that a minimum level in the reducing agent tank has not been reached. 
     
     
         18 . The exhaust gas after treatment system as claimed in  claim 2  wherein the system has a control device by means of which the pump is triggered depending on the measured values acquired by the sensors and/or depending on the current operating parameters of the internal combustion engine, in particular is triggered via a bus system. 
     
     
         19 . The exhaust gas after treatment system as claimed in  claim 2  wherein there is at least one seal, especially an O-ring seal between the integrated unit and the reducing agent tank. 
     
     
         20 . The exhaust gas after treatment system as claimed in  claim 2  wherein the system has an injection unit with at least one nozzle by which the reducing agent is injected into the exhaust gas stream and/or is atomized in the exhaust gas stream and further comprising an SCR catalytic converter in which the reducing agent is delivered into the exhaust gas stream of the internal combustion engine for selective catalytic reduction, upstream and/or downstream of the SCR catalytic converter there being a sensor for detecting the nitrogen oxide concentration in the exhaust gas.