Canned motor and pump

Abstract

The expense of canned motor and pump assemblies for use in pumping liquids in systems requiring complete liquid containment is minimized in a construction whereby standard pump constructions may be coupled to a canned motor. The invention contemplates utilizing a NEMA standard JM extended shaft for journaling the motor rotor, which shaft extends into the conventional seal cavity of any one of a variety of different types or sizes of rotary driven pumps to be coupled to the rotor therein without the use of a mechanical seal in the pump seal cavity.

1 . A canned motor and pump combination comprising: 
 a motor housing;    a motor stator within said motor housing having a generally cylindrical motor rotor receiving opening;    a thin walled cylindrical can snugly received in said rotor receiving opening and having opposed open ends;    a motor rotor received within said can and having a generally cylindrical outer surface located just radially inward of an interior surface of said can to define a small annular gap;    a NEMA standard JM extended shaft impaling said motor rotor and extending axially from both sides of said motor rotor;    end closures closing and sealed to respective ends of said can;    bearings mounted to said end closures to provide journaling for said shaft and to resist thrust loads imparted to said shaft;    a pump housing mounted to one end of said motor housing and sealed thereto, said pump housing including a rotor cavity and a seal cavity intended to receive a mechanical seal for a shaft;    a pump rotor within said rotor cavity;    said NEMA standard JM extended shaft having an end opposite said motor housing one end received in one of said bearings supported by one end closure thereat and an opposite end extending from said motor housing one end through said seal cavity into said rotor cavity and mounting said pump rotor therein, said opposite end being received in another of said bearings supported by an end closure at said housing one end;    said seal cavity being characterized by the absence of a mechanical seal whereby fluid in said pump cavity may flow therefrom through said another bearing, about said motor rotor through said gap while being contained by said can and through said one bearing to a return path to said pump cavity; and    said one end closure further sealing said can opposite end except for said return path.    
   
   
       2 . The canned motor and pump combination of  claim 1  wherein said motor housing and said pump housing are joined at an interface, said interface including a first nose extending axially from said motor housing toward said pump housing and about said shaft and a second nose extending axially from said pump housing toward said motor housing about said shaft, said noses being in tight telescoping relation with one another.  
   
   
       3 . The canned motor and pump combination of  claim 2  further including an annular seal between said noses at said interface.  
   
   
       4 . The canned motor and pump combination of  claim 3  wherein said second nose has an annular interior surface at least partially defining said seal cavity.  
   
   
       5 . The canned motor and pump combination of  claim 3  wherein one of said noses includes an interior stepped surface and the other of said noses includes an exterior stepped surface and said annular seal is disposed between and sealingly engages said stepped surfaces.  
   
   
       6 . The canned motor and pump combination of  claim 1  wherein said return path includes a bore in said NEMA standard JM extended shaft.  
   
   
       7 . A canned motor and pump combination comprising: 
 a motor housing;    a motor stator within said motor housing having a generally cylindrical motor rotor receiving opening;    a thin walled cylindrical can snugly received in said rotor receiving opening and having opposed open ends;    a motor rotor received within said can and having a generally cylindrical outer surface located just radially inward of an interior surface of said can to define a small annular gap;    a NEMA standard JM extended shaft impaling said motor rotor and extending axially from both sides of said motor rotor;    end closures closing and sealed to respective ends of said can;    bearings mounted to said end closures to provide journaling for said shaft and to resist thrust loads imparted to said shaft;    a pump housing mounted to one end of said motor housing and sealed thereto at an interface with said interface including a first nose extending axially from said motor housing toward said pump housing and about said shaft and a second nose extending axially from said pump housing toward said motor housing about said shaft, said noses being in tight telescoping relation with one another, and a rotor cavity within said pump housing including a seal cavity intended to receive a mechanical seal for a shaft, said rotor cavity being located at least in part in said second nose;    a pump rotor within said rotor cavity;    said NEMA standard JM extended shaft having an end opposite said motor housing one end received in one of said bearings supported by one end closure thereat and an opposite end extending from said motor housing one end into said rotor cavity through said seal cavity and mounting said pump rotor in said rotor cavity, said opposite end being received in another of said bearings supported by an end closure at said housing one end;    said seal cavity being characterized by the absence of a mechanical seal whereby fluid in said pump cavity may flow therefrom through said another bearing, about said rotor shaft through said gap while being contained by said can and then through said one bearing;    a return path for fluid including a bore in said shaft extending to said pump cavity; and    said one end closure further sealing said can opposite end.    
   
   
       8 . The canned motor and pump combination of  claim 7  wherein one of said noses includes an interior step surface and the other of said noses includes an exterior step surface and an annular seal disposed between and sealingly engaging said step surfaces.  
   
   
       9 . A canned motor and pump combination comprising: 
 a motor housing;    a motor stator within said motor housing having a generally cylindrical motor rotor receiving opening;    a thin walled cylindrical can snugly received in said rotor receiving opening and having opposed open ends;    a motor rotor received within said can and having a generally cylindrical outer surface located just radially inward of an interior surface of said can to define a small annular gap;    a shaft impaling said motor rotor, said shaft including a nominally central section on which said motor rotor is mounted, bearing receiving sections on each side of said nominally central section, and a seal mounting section to a side of one bearing receiving section remote from said nominally central section and intended to mount a mechanical seal and terminating in a pump rotor mounting end;    end closures closing and sealed to respective ends of said can;    bearings mounted to said end closures to provide journaling for said shaft and to resist thrust loads imparted to said shaft and received on respective ones of said bearing receiving sections;    a pump housing mounted to one end of said motor housing and sealed thereto, said pump housing including a rotor cavity and a seal cavity intended to receive a mechanical seal for a shaft, said rotor cavity surrounding said pump rotor receiving end and said seal cavity surrounding said seal mounting section of said shaft;    a pump rotor within said rotor cavity;    said seal cavity and said seal mounting section of said shaft being characterized by the absence of a mechanical seal whereby fluid in said pump cavity may flow therefrom through said another bearing, about said motor rotor through said gap while being contained by said can and through said one bearing to a return path to said pump cavity; and    said one end closure further sealing said can opposite end except for said return path.    
   
   
       10 . The canned motor and pump combination of  claim 9  wherein said nominally central section and said bearing receiving section are separated by annular shoulders on said shaft and said seal mounting section is separated at said side of said one bearing receiving section by a shoulder and together with said pump rotor mounting end being of reduced diameter in relation to the remainder of said shaft.  
   
   
       11 . A canned motor and pump combination comprising: 
 a motor housing;    a motor stator within said motor housing having a generally cylindrical motor rotor receiving opening;    a thin walled cylindrical can snugly received in said rotor receiving opening and having opposed open ends;    a motor rotor received within said can and having a generally cylindrical outer surface located just radially inward of an interior surface of said can to define a small annular gap;    a shaft impaling said motor rotor, said shaft including a nominally central section on which said motor rotor is mounted, bearing receiving sections on each side of said nominally central section, and a seal mounting section of reduced diameter to a side of one bearing receiving section remote from said nominally central section and intended to mount a mechanical seal and terminating in an end adapted to be keyed to a pump rotor to mount a pump rotor within a pump cavity within a pump housing;    end closures closing and sealed to respective ends of said can;    bearings mounted to said end closures to provide journaling for said shaft and to resist thrust loads imparted to said shaft and received on respective ones of said bearing receiving sections;    a pump housing mounted to one end of said motor housing and sealed thereto, said pump housing including a rotor cavity and a seal cavity intended to receive a mechanical seal for a shaft, said rotor cavity surrounding said pump rotor receiving end and said seal cavity surrounding said seal mounting section of said shaft;    a pump rotor within said rotor cavity;    said seal cavity and said seal mounting section of said shaft being characterized by the absence of a mechanical seal whereby fluid in said pump cavity may flow therefrom through said another bearing, about said motor rotor through said gap while being contained by said can and through said one bearing to a return path to said pump cavity; and said one end closure further sealing said can opposite end except for said return path.