Pump

Claim 1

IN A PUMP OF THE TYPE DESCRIBED, INCLUDING A HOUSING WITH A PUMPING CHAMBER HAVING A CYLINDRICAL WALL, AN EXTERNAL ROTOR GEAR HAVING A DISC-SHAPED SUPPORT PLATE WITH AN OUTER SURFACE CONCENTRIC WITH AND FACING SAID WALL, AN INTERNAL IDLER GEAR ROTATABLY MOUNTED IN SAID HOUSING AND ELECTRICALLY MOUNTED WITH RESPECT TO SAID ROTOR GEAR, THE TEETH OF SAID GEARS MESHING WITH EACH OTHER DURING ONE PORTION OF THEIR ROTATIVE MOVEMENT AND SEPARATED FROM EACH OTHER BY A PARTITION DURING ANOTHER PORTION OF THEIR ROTATIVE MOVEMENT, MEANS TO DRIVE SAID GEARS INCLUDING A BEARING IN SAID HOUSING, A SHAFT EXTENDING THROUGH SAID BEARING AND MEANS FOR DRIVINGLY CONNECTING SAID SHAFT TO SAID ROTOR, AN INLET PORT IN SAID PUMP HOUSING TO RECEIVE LIQUID UNDER LOW PRESSURE AND AN OUTLET PORT IN SAID PUMP HOUSING TO TRANSMIT LIQUID UNDER SUBSTANTIALLY HIGHER PRESSURE FROM SAID GEARS, A FACE FORMED IN SAID HOUSING AND A COOPERATING OPPOSITE FACE FORMED ON SAID ROTOR REARWARD OF THE TEETH THEREON, ONE OF SAID FACES HAVING A SEALING SURFACE AND THE OTHER OF SAID FACES HAVING A PLURALITY OF RADIALLY EXTENDING VANES EXTENDING AXIALLY AND TERMINATING IN A COMMON SECOND SEALING SURFACE SUCH THAT SAID VANES MAKE SEALING CONTACT WITH SAID FIRST FACE WHEN SAID ROTOR GEAR IS ROTATED IN SAID HOUSING, SAID VANES BEING RELATIVELY NARROW WITH RESPECT TO THE SPACE BETWEEN THEM TO PROVIDE A SERIES OF PRESSURE BALANCING CAVITIES OF SUCH SIZE THAT THE TOTAL AREA OF SAID CAVITIES IS SUBSTANTIALLY EQUAL TO THE AREA OF THE FACE HAVING A SEALING SURFACE, AND A SERIES OF PASSAGES AFFORDING COMMUNICATION BETWEEN SAID RESPECTIVE CAVITIES AND THE PUMPING CHAMBER TO EQUALIZE THE PRESSURE BETWEEN RESPECTIVE CAVITIES AND AT PORTION OF THE PUMPING CHAMBER IMMEDIATELY ADJACENT THERETO, THE IMPROVEMENT COMPRISING: MEANS FOR REDUCING THE RADIAL FORCE ON SAID BEARING CAUSED BY A DIFFERENTIAL IN PRESSURE BETWEEN FLUID AT DISCHARGE PRESSURE AND FLUID AT INTAKE PRESSURE ACTING ON SAID OUTER ROTOR SURFACE AND BETWEEN THE ROTOR SURFACE AND HOUSING WALL, SAID FORCE LOWERING MEANS INCLUDING A LOW RESISTANCE FLUID CONNECTION BETWEEN A PORTION OF THE PUMP SUBJECTED TO FLUID AT THE DISCHARGE PRESSURE AND A PORTION OF SAID OUTER SURFACE ADJACENT SAID INLET PORT WHEREBY SAID PORTION ADJACENT SAID INLET PORT IS ALOS SUBJECTED TO DISCHARGE PRESSURE SO THAT THE AREA OF SAID SURFACE SUBJECTED TO A PRESSURE DIFFERENTIAL IS REDUCED.