Metering system for a liquid medium, particularly a urea-water solution

Abstract

The invention relates to a dosing system for a liquid reduction medium enabling precise dosing of the reduction medium in the exhaust gas system of an internal combustion engine. This is carried out particularly by using a quick and safe closing of a pressure-actuated dosing valve. Simultaneously, the dosing system according to the invention also enables the dissipation of the pressure impulses resulting due to the closing movement of the dosing valve.

1 - 10 . (canceled) 
     
     
         11 . A metering system for a liquid medium, in particular a liquid reducing agent, such as an aqueous urea-water solution the metering system, having a tank, a metering pump, and a metering valve, a pressure side of the metering pump and the metering valve communicating with one another through a first line, and the tank and an intake side of the metering pump communicating with one another through a second line, wherein a first check valve is provided in the first line. 
     
     
         12 . The metering system as defined by  claim 11 , wherein a reciprocating motion of the metering pump is transmitted at least partially to a valve member of the first check valve. 
     
     
         13 . The metering system as defined by  claim 12 , wherein the metering pump includes a diaphragm and the reciprocating motion of the diaphragm is transmitted at least partially to the valve member of the first check valve. 
     
     
         14 . The metering system as defined by  claim 13 , wherein the valve member of the first check valve is lifted from a first valve seat as soon as the reciprocating motion of the metering pump exceeds a minimum stroke. 
     
     
         15 . The metering system as defined by  claim 11 , wherein the first check valve is spring-loaded. 
     
     
         16 . The metering system as defined by  claim 12 , wherein the first check valve is spring-loaded. 
     
     
         17 . The metering system as defined by  claim 13 , wherein the first check valve is spring-loaded. 
     
     
         18 . The metering system as defined by  claim 14 , wherein the first check valve is spring-loaded. 
     
     
         19 . The metering system as defined by  claim 11 , wherein the first check valve is embodied as a double-acting check valve, and a second valve seat of the first check valve communicates hydraulically with the tank or the intake side of the metering pump via a connecting line. 
     
     
         20 . The metering system as defined by  claim 18 , wherein the first check valve is embodied as a double-acting check valve, and a second valve seat of the first check valve communicates hydraulically with the tank or the intake side of the metering pump via a connecting line. 
     
     
         21 . The metering system as defined by  claim 19 , wherein a pressure maintenance valve, in particular an adjustable pressure maintenance valve, is provided, in the connecting line. 
     
     
         22 . The metering system as defined by  claim 20 , wherein a pressure maintenance valve, in particular an adjustable pressure maintenance valve, is provided in the connecting line. 
     
     
         23 . The metering system as defined by  claim 11 , wherein a second check valve is provided in the second line. 
     
     
         24 . The metering system as defined by  claim 12 , wherein a second check valve is provided in the second line. 
     
     
         25 . The metering system as defined by  claim 13 , wherein a second check valve is provided in the second line. 
     
     
         26 . The metering system as defined by  claim 11 , wherein the metering valve is pressure-actuated. 
     
     
         27 . The metering system as defined by  claim 12 , wherein the metering valve is pressure-actuated. 
     
     
         28 . The metering system as defined by  claim 13 , wherein the metering valve is pressure-actuated. 
     
     
         29 . The metering system as defined by  claim 11 , wherein the metering pump is actuated by a final control element of an actuator, in particular by an armature of an electromagnet. 
     
     
         30 . The metering system as defined by  claim 12 , wherein the metering pump is actuated by a final control element of an actuator, in particular by an armature of an electromagnet.