Pump

Abstract

The invention relates to a pump having a pump casing, in which a pump chamber is formed, having an inlet leading to it and an outlet leading away from it. In the pump chamber there is a pump impeller, which is secured to a drive shaft, which can be driven in rotation and is mounted rotatably in bearings in the pump casing. Surfaces of the pump chamber which bear against the surfaces of the pump impeller and surfaces of the pump impeller which bear against the surfaces of the pump chamber have a coating of low thickness and high hardness which is applied by physical vapor deposition.

What is claimed is:  
     
         1 . A pump, comprising: 
 a pump casing, in which a pump chamber is formed, which has an inlet leading to the casing and an outlet leading away from the casing; and    a pump impeller which is arranged in the pump chamber and is secured to a drive shaft, which can be driven in rotation and is mounted rotatably in bearings in the pump casing, wherein 
 surfaces of the pump chamber which bear against surfaces of the pump impeller and/or surfaces of the pump impeller which bear against surfaces of the pump chamber have a coating of low thickness and high hardness which is applied by physical vapor deposition.  
   
     
     
         2 . The pump according to  claim 1 , wherein the drive shaft is mounted rotatably in bearing bores in the pump casing, the bearing bores and/or the drive shaft having a coating of low thickness and high hardness which is applied by physical vapor deposition.  
     
     
         3 . The pump according to  claim 1 , wherein the pump is a flow pump.  
     
     
         4 . The pump according to  claim 3 , wherein the flow pump is a peripheral impeller or side channel pump.  
     
     
         5 . The pump according to  claim 1 , wherein the surface of the pump chamber is provided with a coating which is applied by physical vapor deposition.  
     
     
         6 . The pump according to  claim 1 , wherein the surfaces of the fuel-carrying parts of the pump are provided with a coating which is applied by physical vapor deposition.  
     
     
         7 . The pump according to  claim 1 , wherein the coating has a thickness of approximately 2 μm to approximately 5 μm.  
     
     
         8 . The pump according to  claim 1 , wherein the coating is a chromium nitride layer.  
     
     
         9 . The pump according to  claim 1 , wherein the pump casing and/or pump impeller comprises metal or a metal alloy.  
     
     
         10 . The pump according to  claim 1 , wherein the pump casing and/or pump impeller comprises a plastic.  
     
     
         11 . The pump according to  claim 1 , wherein the pump is a fuel pump.