Pump

Abstract

A gear pump includes a pump body 22 which defines a cavity hole 72 which holds a separate cavity body. The cavity body defines channels and a pump cavity holding a pair of gears. An inlet and outlet are connected to the channels. The separate cavity body may be manufactured separately and only this component needs to be manufactured to very accurate tolerances.

1 . A pump system comprising:
 a pump body having a pair of gears located in a pump cavity and defining channels;   an inlet and an outlet connected to the channels of the pump cavity; and   a motor connected to a longitudinal shaft for driving the gears;   wherein one of the gears is a free gear located in the pump cavity by the walls of the cavity, and   the pump body defines a cavity hole and the pump cavity and channels are defined in a cavity block mounted in the cavity hole, the cavity block being free to move laterally in the cavity hole.   
     
     
         2 . A pump system according to  claim 1 , further comprising channels through the cavity block connecting the inlet and the outlet to the pump cavity,
 further comprising a shallow channel of thickness no greater than 30% of the thickness of the cavity block between the channels and the pump cavity to introduce fluid into the pump cavity and to extract fluid from the pump cavity.   
     
     
         3 . A pump system according to  claim 1  wherein the pump cavity and channels extend through the cavity block with constant cross section. 
     
     
         4 . A pump system according  claim 1 , further comprising a pad having the same cross section as the cavity block, the pad being mounted adjacent the cavity block within the cavity hole. 
     
     
         5 . A pump system according  claim 1  comprising:
 a drive unit enclosing the motor; 
 a pump unit including the pump body, the cavity block in the pump body, the inlet, the outlet and the gears; 
 wherein the pump unit is a removable pump unit which may be separated from the drive unit. 
 
     
     
         6 . A pump system according to  claim 1 , wherein the pump unit further comprises a driven disk, the driven disk being connected to the longitudinal shaft and facing the drive unit, the longitudinal shaft passing through the pump body,
 further comprising a drive disk arranged on motor in the drive unit and meshed with the driven disk.   
     
     
         7 . A pump system according to  claim 1  further comprising a detent in the pump unit arranged to engage with a flange on the drive unit to hold the pump unit on the drive unit. 
     
     
         8 . A pump system according to  claim 1 , wherein the motor comprises a motor housing defining a motor cavity therein cooperating with a drive unit on a shaft, the drive unit being located in the motor cavity. 
     
     
         9 . A pump system according to  claim 1  further comprising a PTFE shim between the gears in the pump cavity and the cover, the PTFE shim sealing the top of the pump cavity. 
     
     
         10 . A pump system according to  claim 1 , wherein the pair of gears are helical gears. 
     
     
         11 . A pump system according to  claim 1 , wherein the motor is free to move laterally within a motor housing by at least 0.1 mm. 
     
     
         12 . A pump system according to  claim 1  wherein the cavity block is of plastics containing filler. 
     
     
         13 . A pump system according to  claim 12  wherein the cavity block is of bronze-loaded PTFE.