Abstract:
A rotary pump for pumping liquids includes a motor, a shaft that is driven by the motor, an impeller that is attached to the shaft, a rolling element bearing that surrounds the shaft and a bearing housing for the rolling element bearing. The bearing housing defines a lubricant reservoir in a volume of the bearing housing not occupied by the rolling element bearing. The rotary pump can also include a conduit in communication with the bearing housing and a grease cup fitting in communication with the conduit. The motor can rest on a motor support and the grease cup fitting can be easily accessible by locating the fitting outside of a peripheral side wall of the motor support.

Description:
[0001]     This application claims the benefit of Provisional Patent Application Ser. No. 60/605,661, filed Aug. 30, 2004, entitled “Lube Oil Pump Design,” which is incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Vertical liquid medium pump systems are known, an example of such a pump is disclosed in U.S. Pat. No. 6,315,530 and Buffalo Pumps Bulletin 986, entitled “Lube Oil Pumps,” each of which is incorporated by reference. These known pumps are typically used to transport lube oil. Components of the pump are submerged in a reservoir of lube oil and the pump transports the lube oil to a desired location.  
         [0003]     In these known pumps a rolling element bearing supports a main pump shaft and a sealed bearing housing contains the rolling element bearing. The rolling element bearing is lubricated using grease and after a period of operation requires re-lubrication. Re-lubrication of the rolling element bearing in the known pump requires removal of the pump from the reservoir of lube oil and disassembly of the major pump components. This activity is time consuming and complex.  
       SUMMARY OF THE INVENTION  
       [0004]     A rotary pump for pumping liquids includes a motor, a shaft that is driven by the motor, an impeller that is attached to the shaft, a rolling element bearing that surrounds the shaft and a bearing housing for the rolling element bearing. The bearing housing defines a lubricant reservoir in a volume of the bearing housing not occupied by the rolling element bearing. The rotary pump can also include a conduit in communication with the bearing housing and a grease cup fitting in communication with the conduit. The motor can rest on a motor support and the grease cup fitting can be easily accessible by locating the fitting outside of a peripheral side wall of the motor support.  
         [0005]     The lubricant reservoir in the bearing housing can have a volume great enough to store spent lubricant used to lubricate the rolling element bearing. In one embodiment, the lubricant reservoir can have a volume greater than 2.25 cubic inches. In another embodiment, the lubricant reservoir can have a volume greater than 5 cubic inches. The lubricant reservoir can also have a volume less than 12 cubic inches. The shape of the lubricant reservoir can take many different configurations, including a cylindrical cavity, a frustoconical cavity, a rectangular cavity, a polygonal cavity, as wells as other configurations. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a side elevation view, partially in cross-section, of a rotary pump.  
         [0007]      FIG. 2  is a close-up view, partially in cross-section, of an upper portion of the rotary pump of  FIG. 1 .  
         [0008]      FIG. 3  is a close-up view similar to  FIG. 2  of a known rotary pump. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0009]     A new rotary pump will be described in comparison to a known rotary pump, however the invention is not limited to simply an improvement over the described known rotary pump. The invention can be used in other environments and with other rotary pumps. For ease of understanding the differences between the known rotary pump and the new rotary pump, the figure numbers of the known pump will correspond to the reference numbers of the new pump, except that the reference numbers for the known pump are increased by one hundred.  
         [0010]     With reference to  FIG. 1 , a rotary pump  10  includes a motor support  12  that supports a motor  14  (depicted schematically). The motor  14  drives an elongated generally cylindrical pump shaft  16  that connects to an impeller  18 . The pump shaft  16  can have different diameters along its length. The lower portion of the pump  10  is placed in a reservoir  20  of liquid, typically lube oil, to be transported or pumped. The motor support  12  mounts on a rigid cover plate  22  and includes peripheral side wall  24  having openings  26 . A connecting column  28  attaches to and extends from the cover plate  22  to surround the shaft  16 . The connecting column  28  also attaches to a casing cover  32 , which in combination with the casing  34  provides a housing for the impeller. Liquid enters the casing  34  through a lower inlet  36  where it passes through the impeller  18  en route to a discharge pipe assembly  40 . These components are also found on a known rotary pump.  
         [0011]      FIG. 3  discloses an upper section of a known pump  110  where a rolling element bearing  138  supports the pump shaft  116 , similar to the pump shaft  16  described above. The bearing  138  surrounds the circumference of the pump shaft  116 . An end of the connecting column  128  adjacent the cover plate  122  includes a stepped cylindrical cavity  142  that is concentric with the pump shaft  116 . The cavity  142  can be described as stepped in that the cavity includes an upper vertical side wall  144  that abuts and/or bears against a radial side wall  146  of the bearing  138  and a horizontal ledge  148  formed at a lower end of the upper side wall  144 . A lower annular wall  152  of the bearing  138  rests on and/or bears against the ledge  148 . A lower vertical side wall  154  extends between the ledge  148  and a horizontal base wall  156  of the cavity  142 . A gasket or lip seal  158  surrounds the pump shaft  116  and is provided to seal the cavity  142  at the base wall  156 .  
         [0012]     With continued reference to  FIG. 3 , a bearing housing cover  162  attaches to the connecting column  128  via fasteners  164  to provide a bearing housing for the rolling element bearing  138 . A gasket  166  or other sealing material can be interposed between the bearing housing cover  162  and the connecting column  128  to seal the bearing housing. Also, a gasket or lip seal  168  is provided at the top of the bearing housing cover  162  to contain lubricant within the bearing housing during operation of the pump  110  and to isolate grease lubricant for the rolling element bearing  138  from the liquid lubricant in the reservoir  120 .  
         [0013]     The rolling element bearing  138  is typically lubricated using grease. With reference to  FIG. 3 , a grease cup  172  communicates with a conduit  174  that extends through the bearing housing cover  162 . Through the grease cup  172  and conduit  174  grease lubricant can be introduced into the bearing housing and to the bearing  138 . After a period of operation of the pump  110 , the bearing  138  needs to be re-lubricated. In the embodiment depicted in  FIG. 3 , the volume of the cavity  142  of the bearing housing is small. The vertical distance between the lower wall  152  of the bearing  138  (or the horizontal ledge  148 ) and the base wall  156  of the cavity  142  is approximately 0.25″. Because of the small volume of the cavity  142 , very little volume is available for spent grease lubricant. Therefore, to re-lubricate the bearing  138 , the pump  110  must be disassembled to remove the spent grease. This requires removal of the pump  110  from the reservoir  120  and complex disassembly and re-assembly of the pump. It is desirable to lengthen the time between re-lubrication cycles.  
         [0014]     With reference to  FIG. 2 , the cavity  42  at the upper end of the connecting column  28  is larger than the known cavity  142  depicted in  FIG. 3 . In the embodiment depicted in  FIG. 2 , the distance between the horizontal ledge  48  and the base wall  56  of the cavity is 1.325″. The diameter of the base wall  56  can remain the same as the diameter of the base wall  156  in the known cavity  142 , which in the depicted embodiments is 3.25″. Accordingly, the volume of the cavity  42  where the spent lubricant can reside, i.e. a spent lubricant reservoir, is approximately 10.99 cubic inches in the new pump design as compared to the spent lubricant reservoir of the known cavity  142  which is approximately 2.07 cubic inches. This increase in volume of the cavity  42  allows for replenishment of the grease lubricant at specified intervals without disassembly of the pump  10  because the spent lubricant can reside in the cavity  42  below the bearing  38 . An increase in the size of the cavity  42  has been found desirable, yet this increase can be achieved by increasing the vertical dimension between the bearing  38  and the base wall  56  of the cavity to any dimension and need not be to the extent described above. The other portions of the cavity  42 , for example the upper vertical side wall  44  and the horizontal dimension of the ledge  48  can retain the same dimensions as the known pump  110 ; however these dimensions can also change should such a change be desirable. Furthermore, the area of the base wall  56  of the cavity  42  could also increase, which would increase the volume of the spent lubricant reservoir. For example, the cavity  42  could take a frustoconical configuration where the lower side wall  44  would be angled so that even more spent lubricant could be accommodated. Many possible configurations exist to increase the size of the cavity  42 .  
         [0015]     Grease lubricant is introduced into the bearing housing of the new pump  10  in a similar manner as the known pump  110  in that a grease cup  72  communicates with a conduit  74  that extends through the bearing housing cover  62 . In the new pump design, the grease cup  72  is located outside the peripheral side wall  24  of the motor support  12 . Accordingly, the conduit  74  extends through one of the openings  26  in the motor support  12 . This provides a more accessible location for personnel performing grease replenishment. The location of the grease cup  172  in the known pump  110  was adjacent the rotating pump shaft  116  in an area isolated by a guard (not shown). With the conduit  74  being long enough so that the grease cup  72  is located beyond the peripheral side wall  24 , a conduit support  76  is provided that rests on and is attached to the cover plate  22 . The conduit support  76  can be a piece of angle having a notch that receives the conduit  74 .  
         [0016]     The new pump design can also include a vent fitting  80  spaced from the conduit  74  and extending through the bearing housing cover  62  to communicate with the cavity  42 . The vent fitting  80  allows pressure and excess grease lubricant to escape from the bearing housing while maintaining the integrity of the lip seals  68 . The vent fitting  80  can be a form of a one-way valve, e.g. one-way check valve or the like, which allows pressure and excess lubricant to escape while precluding foreign contaminants from entering through the fitting.  
         [0017]     The new rotary pump has been described in particular detail, however the invention should not be limited to the specific embodiments discussed above. As just one example, a specific bearing element was described above; however, the invention can be used with other bearing elements. Other modifications and alterations will come to those skilled in the art who have read the preceding description. The invention should only be limited by the appended claims, and the claims should be read to include all modifications and alterations that come within the scope of the claims and the equivalents thereof.