Patent Publication Number: US-2011073412-A1

Title: Axial fan compact bearing viscous pump

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to a compact bearing for axial fans. More particularly, the invention relates a viscous pump to provide pumped lubricating fluid to bearings. 
     Conventional lubrication systems for large rotating equipment such as turbine-generators, axial fans, etc., have employed a central pump with pipes leading to the various bearings to provide a flow of lubricating oil to the bearings. There has been a need for a simple means to lubricate each bearing separately without the need for extensive piping to and from a central pump unit. 
     The foregoing illustrates limitations known to exist in conventional lubricating systems. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter. 
     In one embodiment, an axial fan compact bearing viscous pump is provided having: a shaft supported, the shaft rotating in a direction of rotation; an oil disk on the shaft; a viscous pump housing fitting about the oil disk and having an oil inlet therein, an oil outlet therein, the oil outlet being spaced from the oil inlet; the viscous pump housing having an oil channel in an inner periphery facing an outer periphery of the oil disk, the oil channel extending only partway around the viscous pump housing inner periphery, the oil channel extending from the oil inlet in the direction of rotation to a point beyond the oil exit. 
     In a further embodiment, two viscous pumps having a common shaft are provided. Further, axial fans can be connected to the ends of the common shaft. In yet a further embodiment, an axial fan compact bearing viscous pump is provided having: two spaced apart bearing housings; a bearing supported within each bearing housing; a shaft supported within each bearing housing, the shaft rotating in a direction of rotation; two oil disks on the shaft, each bearing having an oil disk proximate thereto; a portion of each bearing housing fitting about a respective one of the oil disks and forming a viscous pump housing, the viscous pump housing having an oil inlet therein, an oil outlet therein, the oil outlet being spaced from the oil inlet; the viscous pump housing having an oil channel in an inner periphery facing an outer periphery of the one of the oil disks, the oil channel extending only partway around the viscous pump housing inner periphery, the oil channel extending from the oil inlet in the direction of rotation to a point beyond the oil exit, the viscous pump housing including an oil sump containing oil, the level of the oil at the oil inlet extending above the oil channel adjacent the oil inlet, the bearing housing having an oil conduit extending from the oil inlet to the bearing. 
     The compact bearing may also have axial fans connected to the ends of the common shaft. 
     This and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  shows a cross section of an axial fan compact bearing viscous pump; 
         FIG. 2  shows a cross-section of the axial fan compact bearing viscous pump shown in  FIG. 1 , taken on line  2 - 2 . 
         FIG. 3A  is an enlarged detail of the oil outlet of the axial fan compact bearing viscous pump shown in  FIGS. 1 and 2 ; 
         FIG. 3B  is an enlarged detail of the oil inlet of the axial fan compact bearing viscous pump shown in  FIGS. 1 and 2 ; 
         FIG. 3C  is a second enlarged detail of the oil outlet of the axial fan compact bearing viscous pump shown in  FIGS. 1 and 2 ; 
         FIG. 3D  is an enlarged detail of the oil sump of the axial fan compact bearing viscous pump shown in  FIGS. 1 and 2 ; 
         FIG. 3E  is an enlarged detail of the oil channel of the axial fan compact bearing viscous pump shown in  FIGS. 1 and 2 ; 
         FIG. 4  is a cross section of a compact bearing showing the viscous pumps of  FIG. 1 ; and 
         FIG. 5  is a side view of the compact bearing shown in  FIG. 4  with axial fans attached to outboard ends of the shaft. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 4  shows one preferred embodiment of an axial fan compact bearing  100 . The axial fan compact bearing  100  includes two viscous pumps  10 . As shown in  FIG. 1 , each viscous pump  10  has a bearing housing  12 . A bearing  14  is fitted within a first part of the bearing housing  12 . A shaft  16  is supported by bearing  14 . An oil disk  18  is fitted on the shaft  16  and is positioned adjacent the bearing  14 . The oil disk  18  may be a separate component attached to the shaft  16  or may be formed as part of the shaft  16 . In a preferred design, the oil disk  18  is about 17 inches in diameter. 
     In an alternate embodiment, the axial fan compact bearing  100  can consist of a single viscous pump  10 . Also, in an alternate embodiment, the compact bearing viscous pump  10  is separate from the bearing  14  where both the viscous pump  10  and bearing  14  each have respective housings. In a preferred embodiment, as shown in the Figures, a single housing is used for both the bearing and the viscous pump. 
     A portion  20  of the bearing housing  12  fits about the oil disk  18  defining a viscous pump housing. The clearance between an inner periphery  21  of the viscous pump housing  20  and the oil disk is preferably between 0.004 inches and 0.020 inches. An oil inlet  22  is positioned at a lower portion of the viscous pump housing  20 . Below the oil inlet  22  is an oil sump  34 . In one preferred embodiment shown in the Figures, an oil outlet  24  is positioned at the top of the viscous pump housing  20 . The oil outlet  24  may be positioned at other locations, such as 270 degrees clockwise or 100 degrees clockwise from the oil inlet  22 . 
     An oil channel  30  is formed in the inner periphery  21  of the viscous pump housing  20  and extends in the direction of rotation, as shown in  FIG. 2 , (this is clockwise in  FIG. 2 ) from the oil inlet  22  to the oil outlet  24 .  FIGS. 3B and 3D  show details of the oil inlet  22  and the oil channel  30 . In a preferred embodiment, the depth  40  (see  FIG. 3E ) of the oil channel  30  is about 0.03 inches to 0.150 inches. An oil dam  32  is positioned beyond (in the direction of rotation) of the oil outlet  24  as shown in  FIGS. 3A and 3C . In the preferred embodiment, no scraper in the oil outlet  24  is used to prevent the entrained oil from being transported past the oil outlet  24 . In a preferred embodiment, the oil channel  30  extends just beyond the oil outlet  24 , as shown in  FIGS. 3A and 3C . 
     The viscous pump  10  is filled with oil such that the oil level  36  rises above the oil inlet  22 , as shown in  FIG. 2 . 
     The beginning of the oil channel  30  is below the oil level  36 , as shown in  FIG. 3B . As the shaft  16 , and oil disk  18  thereon, rotates, oil is entrained in the clearance between the oil disk  18  and the viscous pump housing  20 . The entrained oil flows clockwise (the direction of rotation) in the oil channel  30  to the oil outlet  24 . From the oil outlet  24 , the oil is then conveyed in conduits, such as oil conduit  38 , to bearing  14  to lubricate bearing  14 . Oil then flows out of the bearing  14  and back to the oil sump  34 . As needed, the oil may pass through filters and coolers before being returned to the oil sump  34 . 
     The oil channel  30  contraction occurs at a point near the oil outlet  24 . The oil channel  30  expansion occurs at a point below the oil level  36 . As a result, there is no negative pressure gradient (suction) at the oil channel expansion to either excessively draw oil or gas/oil into or across the circumferential gap formed by the oil channel contraction and expansion. One purpose of this arrangement of oil channel contraction and expansion is to reduce or eliminate adverse pressure gradients that can pull fluids into the working channel except within the oil sump. 
     Depending on system requirements, oil from the oil exit  24  may also be conveyed to other components, not shown, such as fan bearings, motor bearings, coolers, filters, etc. 
     In a preferred embodiment, the oil flow from viscous pump  10  is sufficient to lubricate bearing  14  in the event oil flow from an external lubricating system fails to protect bearing  14  while the system is shut down. In a further preferred embodiment, the oil flow from viscous pump  10  provides sufficient lubricating oil to bearing  14  so that no external lubricating system is required. 
     In one preferred embodiment, as shown in  FIG. 4 , the compact bearings has two viscous pumps  10  fitted about a single continuous shaft  16 . The viscous pumps  10  are axially spaced apart with a shaft housing  110  extending between the viscous pumps  10  and surrounding shaft  16 . Shaft  16  extends beyond the outboard ends  17  of the bearing housings  12  so that axial fans  120  can be attached to shaft  16 . 
     Although two viscous pumps  10  are shown in  FIG. 4 , a single viscous pump  10  may be used by itself in other applications. 
     While certain embodiments have been described in the present application, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the claimed invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the claimed invention without departing from its scope. Therefore, it is intended that the claimed invention not be limited to the particular embodiments disclosed, but that the claimed invention will include all embodiments falling within the scope of the appended claims.