Pump for conveying an exhaust gas aftertreatment medium particularly a urea-water solution, for diesel engines

Abstract

A pump for conveying an exhaust gas treatment medium in diesel engines has a pump housing and a piston arranged in the pump housing and movable in the pump housing against a counterforce. The piston pumps an exhaust gas treatment medium form at least one inlet of the pump to at least one outlet of the pump. A diaphragm separates the piston from the exhaust gas treatment medium. The counterforce is provided by at least one spring that is a pressure spring.

1 .- 27 . (canceled)  
   
   
       28 . A pump for conveying an exhaust gas treatment medium in diesel engines, the pump comprising: 
 a pump housing;    a piston arranged in the pump housing and movable in the pump housing against a counterforce, wherein the piston pumps an exhaust gas treatment medium from at least one inlet of the pump to at least one outlet of the pump; and    a diaphragm separating the piston from the exhaust gas treatment medium.    
   
   
       29 . The pump according to  claim 28 , wherein the piston is a hollow piston.  
   
   
       30 . The pump according to  claim 28 , comprising at least one spring generating the counterforce.  
   
   
       31 . The pump according to  claim 30 , wherein the at least one spring is a pressure spring.  
   
   
       32 . The pump according to  claim 30 , wherein the at least one spring is a plate spring.  
   
   
       33 . The pump according to  claim 32 , wherein the plate spring is integrated into the diaphragm.  
   
   
       34 . The pump according to  claim 33 , wherein the plate spring is tightly enclosed by the diaphragm.  
   
   
       35 . The pump according to  claim 28 , wherein the diaphragm is comprised of thermoplastic elastomer or vulcanized elastomer.  
   
   
       36 . The pump according to  claim 28 , comprising at least one solenoid surrounding the piston.  
   
   
       37 . The pump according to  claim 36 , wherein the piston is movable by applying current to the at least one solenoid.  
   
   
       38 . The pump according to  claim 28 , wherein the piston has a bottom.  
   
   
       39 . The pump according to  claim 38 , wherein the diaphragm is fixedly connected to the piston in a movement direction of the piston.  
   
   
       40 . The pump according to  claim 39 , wherein the diaphragm is connected to the bottom of the piston.  
   
   
       41 . The pump according to  claim 38 , wherein the diaphragm has a projection that projects through the bottom of the piston.  
   
   
       42 . The pump according to  claim 41 , further comprising a fastening part embedded in the diaphragm, wherein the projection projects from the fasting part.  
   
   
       43 . The pump according to  claim 42 , comprising a plate spring generating the counterforce, wherein the plate spring is integrated into the diaphragm and is secured on the fasting part  
   
   
       44 . The pump according to  claim 41 , wherein the projection is a threaded pin.  
   
   
       45 . The pump according to  claim 44 , wherein the threaded pin is screwed into the bottom of the piston.  
   
   
       46 . The pump according to  claim 28 , comprising at least one solenoid surrounding the piston, wherein the piston is movable by applying current to the at least one solenoid, wherein the diaphragm rests areally against the bottom of the piston when the solenoid is not actuated.  
   
   
       47 . The pump according to  claim 28 , wherein the diaphragm has a rim that is clamped between the pump housing and a pump head of the pump.  
   
   
       48 . The pump according to  claim 47 , wherein the diaphragm delimits a pump chamber.  
   
   
       49 . The pump according to  claim 48 , wherein the pump chamber is provided in the pump head.  
   
   
       50 . The pump according to  claim 49 , comprising a first check valve that is adapted to close a supply path to the pump chamber.  
   
   
       51 . The pump according to  claim 50 , comprising a second check valve that is adapted to close the at least one outlet.  
   
   
       52 . The pump according to  claim 51 , wherein the first and second check valves operate in opposite directions relative to one another.  
   
   
       53 . The pump according to  claim 51 , wherein the pump head has first and second receiving chambers, wherein first check valve has a first valve body arranged in the first receiving chamber and the second check valve has a second valve body arranged in the second receiving chamber.  
   
   
       54 . The pump according to  claim 53 , wherein an outer diameter of the first and second valve bodies is smaller than an inner diameter of the first and second receiving chambers, respectively.  
   
   
       55 . The pump according to  claim 53 , wherein the first and second receiving chambers are connected to the pump chamber.