Pump assembly

Abstract

A pump assembly comprises first and second gear pumps ( 10, 13 ), each of which has a respective driver gear ( 11, 14 ) and a respective driven gear ( 12, 15 ), wherein the driven gear ( 12 ) of the first gear pump ( 10 ) is arranged to drive the driver gear ( 14 ) of the second gear pump ( 13 ).

1 . A pump assembly comprising a first gear pump, and a second gear pump, each gear pump having a respective driver gear and a driven gear, and the driver gear of the second gear pump being arranged to receive drive from the driven gear of the first gear pump.  
   
   
       2 . A pump assembly according to  claim 1 , further comprising a rotodynamic pump arranged to receive drive from the driver gear of said first gear pump.  
   
   
       3 . A pump assembly according to  claim 2 , wherein the rotodynamic pump is a centrifugal pump.  
   
   
       4 . A pump assembly according to  claim 2 , wherein the first gear pump is disposed between the second gear pump and the rotodynamic pump.  
   
   
       5 . A pump assembly according to  claim 4 , wherein the rotodynamic pump is mounted on an extension of the drive shaft from the driver gear of the first gear pump.  
   
   
       6 . A pump assembly according to  claim 5 , wherein the centrifugal pump is directly mounted on the extension.  
   
   
       7 . A pump assembly according to  claim 1 , wherein the second gear pump has a smaller displacement than the first gear pump.  
   
   
       8 . A pump assembly according to  claim 1 , wherein drive is transmitted to the driver gear of the second gear pump from the driven gear of the first gear pump by a second drive shaft.  
   
   
       9 . A pump assembly according to  claim 8 , wherein opposite ends of the second drive shaft are provided with splines.  
   
   
       10 . A pump assembly according to  claim 9 , wherein internal leakage of fuel from the first gear pump is utilised to lubricate the respective splines of the second drive shaft at the driven gear of the first gear pump and internal leakage from the second gear pump is utilised to lubricate the splines of the second drive shaft at the driver gear of the second gear pump.  
   
   
       11 . A pump assembly according to  claim 1 , wherein for each of the first and second gear pumps, the timing of the meshing of teeth on the driver gear with teeth on the respective driven gear is controlled so that respective peak torques and/or peak pressures of the first and second gear pumps occur out of phase.  
   
   
       12 . A gas turbine engine incorporating a pump assembly as claimed in  claim 1 .  
   
   
       13 . A pump assembly comprising a first gear pump, and a second gear pump, each gear pump having a respective driver gear and a driven gear, wherein for each of the first and second gear pumps the timing of the meshing of teeth on the driver gear with teeth on the respective driven gear is controlled so that respective peak torques and/or peak pressures of the first and second gear pumps occur out of phase.  
   
   
       14 . A pump assembly according to  claim 13 , wherein the second gear pump has a smaller displacement than the first gear pump.