Dosing device

Abstract

The present invention relates to a dosing device ( 15 ) for introducing a liquid medium into an exhaust gas flow of an internal combustion engine ( 1 ) of a motor vehicle. The dosing device ( 15 ) has a pump ( 23 ) to deliver the liquid medium and injects said medium into the exhaust gas flow via a controllable dosing valve ( 13 ). The dosing device ( 15 ) has a 2/2 directional valve ( 17 ) which is arranged in a delivery line ( 19 ) between the pump ( 23 ) and a first low pressure chamber ( 47 ) of the dosing valve ( 13 ).

1 - 10 . (canceled) 
     
     
         11 . A dosing device ( 15 ) for introducing a liquid medium into an exhaust-gas stream of an internal combustion engine ( 1 ) of a motor vehicle, wherein the dosing device ( 15 ) has a pump ( 23 ) for delivering the liquid medium and the medium is injected into the exhaust-gas stream by means of a dosing valve ( 13 ), wherein the dosing device ( 15 ) has a 2/2 directional valve ( 17 ), wherein the dosing valve ( 13 ) has at least one low-pressure chamber ( 47 ) and at least one high-pressure chamber ( 41 ), wherein the low-pressure chamber ( 47 ) and the high-pressure chamber ( 41 ) are delimited by a piston ( 49 ), wherein a part of the piston which delimits the low-pressure chamber has a larger diameter than a part of the piston which delimits the high-pressure chamber, and wherein the 2/2 directional valve ( 17 ) is arranged in a delivery line ( 19 ) between the pump ( 23 ) and the low-pressure chamber ( 47 ) of the dosing valve ( 13 ). 
     
     
         12 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that a delivery volume of the dosing device ( 15 ) is structurally predefined. 
     
     
         13 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that the dosing device ( 15 ) has at least one exchangeable spacer device ( 53 ) for defining a piston stroke in at least one pressure chamber ( 41 ;  47 ,  61 ). 
     
     
         14 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that the 2/2 directional valve ( 17 ) is an integral constituent part of the dosing valve ( 13 ). 
     
     
         15 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that a check valve ( 55 ,  57 ) is arranged between the low-pressure chamber ( 47 ) and the high-pressure chamber ( 41 ), in that the check valve ( 55 ,  57 ) opens when pressure in the low-pressure chamber ( 47 ) is higher than pressure in the high-pressure chamber ( 41 ), and in that the check valve ( 55 ,  57 ) closes when the pressure in the low-pressure chamber ( 47 ) is lower than the pressure in the high-pressure chamber ( 41 ). 
     
     
         16 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that the dosing device ( 15 ) injects a liquid reducing agent for nitrogen oxide reduction into the exhaust-gas stream. 
     
     
         17 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that the dosing device ( 15 ) injects diesel fuel for particle filter regeneration into the exhaust-gas stream. 
     
     
         18 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that a housing ( 33 ) of the dosing valve ( 13 ) has cooling ducts. 
     
     
         19 . The dosing device ( 15 ) as claimed in  claim 11 , characterized in that the dosing device ( 15 ) can be used for adherence to predefined exhaust-gas limit values in an exhaust pipe ( 5 ) within the context of on-board diagnosis. 
     
     
         20 . The dosing device ( 15 ) as claimed in  claim 12 , characterized in that the dosing device ( 15 ) has at least one exchangeable spacer device ( 53 ) for defining a piston stroke in at least one pressure chamber ( 41 ;  47 ,  61 ). 
     
     
         21 . The dosing device ( 15 ) as claimed in  claim 20 , characterized in that the 2/2 directional valve ( 17 ) is an integral constituent part of the dosing valve ( 13 ). 
     
     
         22 . The dosing device ( 15 ) as claimed in  claim 21 , characterized in that a check valve ( 55 ,  57 ) is arranged between the low-pressure chamber ( 47 ) and the high-pressure chamber ( 41 ), in that the check valve ( 55 ,  57 ) opens when pressure in the low-pressure chamber ( 47 ) is higher than pressure in the high-pressure chamber ( 41 ), and in that the check valve ( 55 ,  57 ) closes when the pressure in the low-pressure chamber ( 47 ) is lower than the pressure in the high-pressure chamber ( 41 ).