Device and procedure for axial thrust compensation

Abstract

Compensation for the axial thrust in a pump, in particular a vertical pump, having at least one drive unit and at least one rotary pump unit. In operation of the pump a compensating piston which is axially non-displaceably connected to the shaft of the impeller wheel of the rotary pump unit is subjected to a pressure difference which results from the pump pressure and a lower pressure and from which there is produced a force which is directed in opposite relationship to the axial thrust and which acts on the shaft of the impeller wheel. There are further proposed a method of axial thrust compensation and a method of retrofitting an arrangement for axial thrust compensation to a pump, in particular a vertical pump, and a retrofit module therefore.

1 . A pump comprising:
 at least one rotary pump unit with at least one impeller wheel driven by at least one drive unit, wherein an axial thrust corresponding to the pump pressure acts on a shaft of the at least one impeller wheel in operation of the pump,   wherein the pump has a compensating piston for self-regulating production of a compensating force that at least partially relieves the load of the axial thrust by means of a pressure difference from the pump pressure and a predetermined lower pressure,   wherein the compensating piston is connected to the shaft in force-locking relationship in the axial direction of the shaft and is guided movably in a stationary compensating cylinder, and   wherein the communication of the pump pressure or the predetermined lower pressure to the compensating piston comprises an axial passage in the shaft.   
   
   
       2 . A pump as set forth in  claim 1  wherein the effective piston area is matched to the nominal output of the drive unit. 
   
   
       3 . A pump as set forth in  claim 1  wherein the pump is a vertical pump. 
   
   
       4 . A pump as set forth in  claim 1  wherein the assembly comprising the compensating piston and the compensating cylinder is between the drive unit and the rotary pump unit. 
   
   
       5 . A pump as set forth in  claim 1  wherein the compensating cylinder is fixed at the side of the drive unit, that faces in the direction of the pump. 
   
   
       6 . A pump as set forth in  claim 1  wherein the pump pressure of the rotary pump unit is fed by means of a direct fluidic communication to the side of the rotary pump unit, that is towards the compensating piston. 
   
   
       7 . A pump as set forth in  claim 1  wherein in operation of the pump the predetermined lower pressure is fed by way of a compensating conduit to the side of the rotary pump unit, that is remote from the compensating piston. 
   
   
       8 . A pump as set forth in  claim 1  wherein the assembly comprising the compensating piston and the compensating cylinder is fixed upstream of the rotary pump unit in the delivery direction. 
   
   
       9 . A pump as set forth in  claim 8  wherein the assembly comprising the compensating piston and the compensating cylinder additionally is a hydraulic bearing. 
   
   
       10 . A pump as set forth in  claim 8  wherein the pump pressure of the rotary pump unit is fed by way of a compensating conduit to the side of the rotary pump unit, that is remote from the compensating piston. 
   
   
       11 . A pump as set forth in  claim 1  wherein the predetermined lower pressure is the suction pressure of the pump, that is produced in operation of the pump, or wherein the predetermined lower pressure is the ambient pressure prevailing at the location of operation. 
   
   
       12 . A pump as set forth in  claim 1  wherein the axial passage is in the part of the shaft that extends in the rotary pump. 
   
   
       13 . A pump as set forth in  claim 1  wherein the axial passage is in the part of the shaft that extends in the drive unit. 
   
   
       14 . A pump as set forth in  claim 1  wherein the assembly comprising the compensating piston and the compensating cylinder is in the form of a module arranged between the pump and the drive unit. 
   
   
       15 . A pump as set forth in  claim 14  wherein the module is a retrofit module for retrofitting to an existing pump. 
   
   
       16 . A method of compensating an axial thrust acting on a shaft of a pump, comprising at least one rotary pump unit and at least one drive unit for the rotary pump unit, in operation of the pump, comprising the steps:
 producing a differential pressure between the pump pressure that is produced in operation and a lower pressure than the pump pressure, wherein communicating the lower pressure or the pump pressure to the compensating piston by an axial bore in the shaft, and   producing from the differential pressure a force that acts in opposite relationship to the axial thrust at the shaft and at the shaft self-regulatingly reducing the axial thrust occurring in operation of the pump by means of the differential pressure.   
   
   
       17 . A method of retrofitting axial thrust compensation to a pump comprising at least one rotary pump unit and at least one drive unit for the rotary pump, wherein the method comprises:
 mounting a piston to the pump shaft,   mounting to the pump a cylinder in which the piston can be guided,   producing a feed for the pump pressure produced in operation to the side of the piston, that faces in the direction of the axial thrust,   producing a feed for a predetermined lower pressure than the pump pressure to the other side of the piston, wherein one of the feeds is an axial passage in the shaft, and   setting up the assembly of the piston and the cylinder so that in operation of the pump a pressure difference can be self-regulatingly produced therewith, wherein a force which is dependent on the axial thrust of the pump and in opposite relationship thereto acts on the shaft by means of the pressure difference at the pump shaft.   
   
   
       18 . A method as set forth in  claim 17  and further comprising:
 matching the assembly of the compensating cylinder and the compensating piston to the output of the drive unit of the pump.   
   
   
       19 . A method as set forth in  claim 17  and further comprising:
 equipping a part or the entire shaft of the pump with an axial passage in the part of the shaft that extends through the drive unit and/or in the part of the shaft that extends through the rotary pump unit, wherein the passage is capable of communicating the pump pressure produced in operation or a predetermined lower pressure than the pump pressure to a side of the piston.   
   
   
       20 . A retrofit module for a pump comprising at least one rotary pump unit having at least one impeller wheel driven by at least one drive unit, wherein in operation of the pump an axial thrust corresponding to the pump pressure acts on a shaft of the impeller wheel, the retrofit module comprises:
 an assembly comprising a compensating piston and a compensating cylinder capable of self-regulatingly producing a compensating force which at least partially relieves the load of the axial thrust by means of a pressure difference from the pump pressure and a predetermined lower pressure,   wherein the compensating piston of the retrofit module is capable of being connected to the shaft of the rotary pump unit in force-locking relationship in the axial direction and in that case is guided movably in the compensating cylinder of the retrofit module, which compensating cylinder can be stationarily fixed to the pump.