Internal Gear Pump

Abstract

An internal gear pump with a field replaceable idler is disclosed that may be used for sanitary applications. Access to the idler mainly merely requires removal of the head. Access to the seal assembly disposed at the inboard end of the pump chamber is also fast and easy as removal of the head exposes a fastener that secures the rotor to the drive shaft. Removal of this fastener enables the rotor to be removed with a standard rotor-pulling tool thereby exposing the pump chamber seal assembly, which may be cleaned, serviced or replaced as needed.

What is claimed: 
     
         1 . A pump comprising:
 a bracket including an inboard end, an outboard end and a through hole extending between the inboard and outboard ends;   the outboard end of the bracket being coupled to an inboard end of a case, the inboard end of the case including an opening, the case further including an open outboard end that is covered by and coupled to a head, the case and head defining a pump chamber, the inboard end of the case further including an annular recess that surrounds the opening and that receives a seal assembly;   a shaft including an inboard end and an outboard end, the shaft passing through the through hole of the bracket, the outboard end of the shaft passing through the seal assembly and the inboard end of the case before being detachably coupled to a rotor, the rotor being received in the pump chamber;   the head being sealably and detachably coupled to a dowel, the dowel being coaxially received in an idler that is disposed in the pump chamber;   whereby removal of the head and rotor providing access to the seal assembly through the open outboard end of the case and removal of the head and dowel providing access to the idler.   
     
     
         2 . The pump of  claim 1  wherein the dowel includes an inboard end disposed axially within the idler and an outboard end that is coupled to the head with a first fastener,
 the pump further comprising a seal disposed between the dowel and the head that isolates the first fastener from the pump chamber. 
 
     
     
         3 . The pump of  claim 2  wherein the first fastener passes through the head. 
     
     
         4 . The pump of  claim 1  wherein the dowel includes an inboard end disposed within the idler and an outboard end that is received within a recess disposed within the head,
 the pump further comprising a seal disposed between the dowel and the head that isolates the recess from the pump chamber. 
 
     
     
         5 . The pump of  claim 2  wherein the seal is an o-ring. 
     
     
         6 . The pump of  claim 4  wherein the seal is an o-ring. 
     
     
         7 . The pump of  claim 2  wherein the idler is press-fit over a bushing, the idler and bushing are slip-fit onto the dowel, and
 wherein the idler, bushing and dowel can be removed from the pump chamber and from the head by detaching the first fastener from the head and detaching the head from the case. 
 
     
     
         8 . The pump of  claim 4  wherein the outboard end of the dowel has an outboard diameter and the inboard end of the dowel has an inboard diameter that is larger than the outboard diameter with a shoulder disposed between the inboard and outboard ends of the dowel, and
 wherein the seal is sandwiched between the idler and the shoulder. 
 
     
     
         9 . The pump of  claim 7  wherein the outboard end of the dowel has an outboard diameter and the inboard end of the dowel has an inboard diameter that is larger than the outboard diameter with a shoulder disposed between the inboard and outboard ends of the dowel,
 the outboard end of the dowel being disposed within a recess disposed in the head, 
 the first fastener being coaxial with the dowel and the recess, and 
 wherein the seal is disposed between the idler, the bushing and the shoulder. 
 
     
     
         10 . The pump of  claim 1  wherein the dowel includes an outboard end having an outboard diameter and an inboard end having an inboard diameter that is larger than the outboard diameter with a shoulder disposed between the inboard and outboard ends of the dowel,
 the outboard end of the dowel being disposed within a recess disposed in an inboard side of the head, the inboard end of the head further including a slot that encircles the recess; 
 the pump further comprising a seal disposed in the slot that isolates the outboard end of the dowel from the pump chamber. 
 
     
     
         11 . The pump of  claim 2  further including a bushing disposed between the idler and the dowel, and
 the idler being press-fit onto the bushing and the bushing being slip-fit onto the dowel. 
 
     
     
         12 . The pump of  claim 11  wherein the idler is polymeric and the bushing is ceramic. 
     
     
         13 . The pump of  claim 1  further comprising a tube that extends between the case and the bracket and about an axis of the shaft; and
 wherein the tube is in communication with a source of heat transfer fluid. 
 
     
     
         14 . The pump of  claim 1  wherein the outboard end of the shaft is detachably coupled to the rotor by a second fastener and an annular cover plate, the second fastener having a threaded shaft connected to a fastener head, the threaded shaft passing through the cover plate before being threadably coupled to the outboard end of the drive shaft, the cover plate extending radially outward beyond the outboard end of the drive shaft before being received in an annular recess disposed in the rotor, the fastener head clamping the cover plate against the outboard end of the drive shaft, the cover plate clamping the rotor against the seal assembly. 
     
     
         15 . A pump comprising:
 a bracket including an inboard end, an outboard end and a through hole extending between the inboard and outboard ends;   the outboard end of the bracket being coupled to an inboard end of a case, the inboard end of the case including an opening, the case further including an open outboard end that is covered by and coupled to a head, the case and head defining a pump chamber, the inboard end of the case further including an annular recess that surrounds the opening and that receives a seal assembly;   a shaft including an inboard end and an outboard end, the shaft passing through the through hole of the bracket, the outboard end of the shaft passing through the seal assembly and the inboard end of the case before being detachably coupled to a rotor, the rotor being received in the pump chamber;   at least one of the case and/or bracket including a peripheral channel that accommodates a tube that extends about a central axis of the through hole, shaft and seal assembly, the tube being in communication with a supply of heat transfer fluid;   a dowel coaxially received in an idler that is disposed in the pump chamber;   removal of the head and rotor providing access to the seal assembly through the open outboard end of the case;   the dowel including an inboard end disposed axially within the idler and an outboard end that is received within a recess disposed in the head, the outboard end of the dowel being detachably coupled to the head by a first fastener; and   the pump further comprising a seal disposed between the dowel and the head that isolates the first fastener from the pump chamber.   
     
     
         16 . The pump of  claim 15  wherein the outboard end of the shaft is detachably coupled to the rotor by a second fastener and an annular cover plate, the second fastener having a threaded shaft connected to a fastener head, the threaded shaft passing through the cover plate before being threadably coupled to the outboard end of the drive shaft, the cover plate extending radially outward beyond the outboard end of the drive shaft before being received in an annular recess disposed in the rotor, the fastener head clamping the cover plate against the outboard end of the drive shaft, the cover plate clamping the rotor against the seal assembly. 
     
     
         17 . The pump of  claim 15  wherein the dowel is coupled to the idler by a bushing; and
 wherein the idler, bushing and dowel can be removed from the chamber and the head by detaching the first fastener from the head. 
 
     
     
         18 . The pump of  claim 15  wherein the outboard end of the dowel has an outboard diameter and the inboard end of the dowel has an inboard diameter that is larger than the outboard diameter with a shoulder disposed between the inboard and outboard ends of the dowel, and
 wherein the seal is sandwiched between the idler and the shoulder. 
 
     
     
         19 . The pump of  claim 15  wherein the outboard end of the dowel has an outboard diameter and the inboard end of the dowel has an inboard diameter that is larger than the outboard diameter with a shoulder disposed between the inboard and outboard ends of the dowel,
 the outboard end of the dowel being disposed within a recess disposed in an inboard side of the head, the inboard side of the head further including a slot that encircles the recess; 
 the pump further comprising a seal disposed in the slot that isolates the outboard end of the dowel from the pump chamber. 
 
     
     
         20 . A pump comprising:
 a bracket including an inboard end, an outboard end and a through hole extending between the inboard and outboard ends;   the outboard end of the bracket being coupled to an inboard end of a case, the inboard end of the case including an opening, the case further including an open outboard end that is covered by and coupled to a head, the case and head defining a pump chamber, the inboard end of the case further including an annular recess that surrounds the opening and that receives a seal assembly;   a dowel coaxially slip-fitted into a polymeric idler with a ceramic bushing annularly disposed between the dowel and idler, the idler being disposed in the pump chamber, the dowel being coupled to the head by a first fastener, the dowel including an inboard end disposed axially and within the idler and an outboard end that is received within a recess disposed in the head, the outboard end of the dowel being detachably coupled to the head by a second fastener, the pump further comprising a seal disposed between the dowel and the head that isolates the first fastener from the pump chamber;   a shaft including an inboard end and an outboard end, the shaft passing through the through hole of the bracket, the outboard end of the shaft passing through the seal assembly and the inboard end of the case before being detachably coupled to a rotor, the rotor being received in the pump chamber;   the outboard end of the shaft detachably coupled to the rotor by a second fastener and an annular cover plate, the second fastener having a threaded shaft connected to a fastener head, the threaded shaft passing through the cover plate before being threadably coupled to the outboard end of the drive shaft, the cover plate extending radially outward beyond the outboard end of the drive shaft before being received in an annular recess disposed in the rotor, the fastener head clamping the cover plate against the outboard end of the drive shaft, the cover plate clamping the rotor against the seal assembly; and   wherein removal of the head and rotor providing access to the seal assembly through the open outboard end of the case.