Pump impellers

Abstract

An impeller ( 20 ) for a rotary pump ( 10 ) of the type having an impeller with flexible blades, the impeller being removably located in a pump housing ( 40 ) having a removable end cover for access to the impeller, the impeller ( 20 ) including a drive boss ( 21 ) having a screw threaded aperture ( 80 ) at a free end to permit insertion of a screw threaded shaft ( 81 ) which, when rotated, urges the impeller axially off a drive shaft ( 30 ) on which it is mounted in use.

1 . An impeller for a rotary pump of the type having an impeller with flexible blades, said impeller being removably located in a pump housing having a removable end cover for access to said impeller, said impeller including a drive boss having a screw threaded aperture at one end thereof said impeller, in use, being removable from a pump drive shaft by rotation in said aperture of a screw threaded shaft compressively engageable with a free end of said drive shaft.  
     
     
         2 . An impeller as claimed in    claim 1    wherein said screw threaded shaft includes a drive member for effecting rotation of said shaft.  
     
     
         3 . An impeller as claimed in    claim 2    wherein said drive member comprises a shaped head at a free end of said shaft, said shaped head being engageable in use by a driving tool.  
     
     
         4 . An impeller as claimed in    claim 3    wherein said drive member comprises a bolt head.  
     
     
         5 . An impeller as claimed in    claim 1    including a plurality of flexible blades extending outwardly from the hub, said blades being removably secured in said hub.  
     
     
         7 . An impeller as claimed in    claim 6    wherein the blades can be inserted in or removed from the hub by moving the blades in an axial direction relative to the hub.  
     
     
         8 . An impeller as claimed in    claim 7    wherein the hub has a plurality of equally spaced profiled slots into which corresponding end portions of the blades can be inserted.  
     
     
         9 . An impeller as claimed in    claim 8    wherein each blade is substantially symmetrical such that either of opposed end portions of the blade can be inserted into a respective profiled slot in said hub.  
     
     
         10 . An impeller as claimed in    claim 5    wherein the blades and hub are made from different materials.  
     
     
         11 . An impeller as claimed in    claim 1    wherein a seal is located against at least one end of the hub to establish, in use, substantially water tight zones between respective blades.  
     
     
         12 . An impeller as claimed in    claim 11    wherein said seal is heat resistant.  
     
     
         13 . An impeller as claimed in    claim 12    wherein the seal includes a central aperture.  
     
     
         14 . An impeller as claimed in    claim 13    wherein the seal is an “O” ring.  
     
     
         15 . An impeller as claimed in    claim 1    wherein a drive shaft is attached to the impeller by a lost motion device that allows at least limited relative rotation between the drive shaft and the impeller.  
     
     
         16 . An impeller as claimed in    claim 15    wherein the lost motion device includes at least one impeller key mounted to the impeller and at least one drive shaft key mounted to the drive shaft such that upon rotation of the drive shaft the keys engage to rotate the impeller.  
     
     
         17 . An impeller as claimed in    claim 17    wherein the lost motion device comprises a hollow tube mountable to the impeller, said hollow tube having equally spaced impeller keys formed on an inner circumference thereof and a collar mountable on the drive shaft and having equally spaced drive shaft keys formed on an outer circumference of the collar.  
     
     
         18 . A method of removal of an impeller from a rotary pump of the type having an impeller with flexible blades, said impeller being removably located in a pump housing having a removable end cover for access to said impeller, said method including the step of inserting, into a screw threaded aperture in one end of a drive boss of said impeller, a screw threaded shaft and rotating said shaft into engagement with a free end of an impeller drive shaft to urge said impeller outwardly of said pump housing.