Abstract:
A non-contact sealing system for shaft bearings lubricated with lubricating fluid employs a centrifugal pressurizing seal having a stator ring and a rotor ring with a centrifugal pressure chamber to pressurize the fluid and deliver the fluid to remote portions of a bearing through channels in the bearing housing. The system enables bearings to be lubricated at stations remote from the system as well as bearings supporting shafts oriented in the vertical direction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority from Provisional Application 61/935,026 filed Feb. 3, 2014 and incorporates the disclosure of the provisional application herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a system for sealing bearings against the loss of a lubricating fluid and admission of contamination using a non-contact seal. A non-contact seal for a bearing is a seal preventing the loss of lubricating fluid from a bearing, or the admission of contaminants, and having low resistance to rotation because sealing surfaces moveable rotationally relative to one another are not in frictional contact. 
       BACKGROUND OF THE INVENTION 
       [0003]    Non-contact seals are known in the art and generally fall into categories of labyrinth, hybrid labyrinth, and centrifugal pressure seals. Such seals are used to keep lubricating fluids in a rotatable shaft bearing, and may also keep foreign contaminants out of the bearing. 
         [0004]    An example of a centrifugal pressure seal for roller or ball bearings having a lubricating fluid is found in U.S. Pat. No. 6,170,832 to Ernst. In such a seal a centrifugal pumping chamber pressurizes a portion of the lubricating fluid when the bearing is rotated, and feeds the pressurized lubricating fluid to the bearing to fill the bearing with lubricant or replenish lubricant that was lost. 
         [0005]    A number of environments that until now could use the advantages of a non-contact seal have not been able to take advantage of the centrifugal pressure seals for various reasons. For example, the seal shown in the Ernst patent is situated immediately adjacent the bearing being serviced by the non-contact seal. Greater flexibility in use of the centrifugal pressure seal would be enjoyed if the seal did not have to be directly adjacent the bearing. The centrifugal seal could also enjoy wider use if the seal could service multiple bearings from a location remote from the bearing. Also the centrifugal seal until now has not been available for use with vertically oriented shafts because of the problem of the lubricating fluid draining from the seal. Solutions to these and other problems are provided by the present invention. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention relates to a non-contact sealing system for shaft bearings lubricated with a lubricating fluid by a centrifugal pressure seal. The system includes a bearing housing that supports a shaft in the bearing to be sealed for rotation about the axis of the shaft. A stator ring is mounted in the bearing housing, and has an annular channel circumscribing the ring and the shaft supported by the housing. 
         [0007]    A rotor ring is mounted on the shaft supported by the bearing in the bearing housing adjacent the stator ring. The rotor ring is rotatable with the shaft and has an annular centrifugal pressurizing chamber circumscribing the rotor ring for pressurizing lubricating fluid in the chamber when the rotor ring is rotated with the shaft. The annular centrifugal pressurizing chamber of the rotor ring is positioned in the annular channel of the stator ring and has at least one discharge port at the outer periphery of the chamber for discharging pressurized lubricating fluid into the annular channel of the stator ring. The pressurization arises due to centrifugal force when the chamber and the rotor ring spin with the shaft and the lubricating fluid in the chamber is thrust radially outward. So-called pumping rings or discs may be placed in the chamber to stop splashing of the lubricant and maintain laminar flow between the rings as the fluid is spun in the chamber. 
         [0008]    The bearing housing has fluid conduits communicating with the annular channel of the stator ring to pick up the lubricating fluid pressurized in the centrifugal pressurizing chamber and discharged into the annular channel of the stator ring. The conduits then carry the pressurized lubricating fluid to a bearing supported remotely in the bearing housing. 
         [0009]    The invention as described enables the sealing system adjacent a bearing to deliver the pressurized lubricant to the side of the bearing opposite from the stator and rotor rings, or to several remote bearings that share the same lubricating fluid. 
         [0010]    The invention also allows the sealing system to be employed with shafts that are vertically oriented by delivering the pressurized lubricating fluid to upper bearings and allowing the pumped fluid to drain by gravity back down through bearing or bearings to the pressurizing chamber. In such an installation, the pressurizing chamber may be enlarged to define a reservoir for extra lubricating fluid that is needed to circulate through the larger system. The system is also self-sealing by virtue of the reservoir at the bottom. 
         [0011]    The advantages enumerated above and other advantages will be appreciated by those skilled in the art from the following description of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a cross-sectional view of a horizontal shaft supported by two bearings, each of which employs the non-contact sealing system of the present invention. 
           [0013]      FIG. 2  is an enlarged fragmentary cross-sectional view illustrating the upper portion of  FIG. 1  in greater detail. 
           [0014]      FIGS. 3   a - 3   d  illustrate one embodiment of the stator ring of the present invention. 
           [0015]      FIG. 4  is a cross-sectional view of a rotor ring that cooperates with the stator ring of  FIGS. 3   a - 3   d.    
           [0016]      FIG. 5  is a cross-sectional view of a vertically oriented shaft supported by two bearings and employing the non-contact sealing system of the present invention. 
           [0017]      FIG. 6  is a fragmentary cross-sectional view illustrating the lower, left portion of  FIG. 5  in greater detail. 
           [0018]      FIG. 7  is a perspective view of a fluid distribution ring employed in the embodiment of  FIG. 5 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]      FIGS. 1 and 2  illustrate one embodiment of the non-contact sealing system  10  used in connection with a shaft  12  supported for rotation about a horizontal shaft axis  14  by means of two ball bearings  16  and  18  in a bearing housing  20 . 
         [0020]    For purposes of illustration, the lengths of the shaft  12  and the bearing housing  20  have been shortened, and as a consequence the bearings  16  and  18  are axially positioned almost adjacent one another. The length of the shaft  12 , the bearing housing  20  and axial spacing of the bearings can be much greater, and the sealing system  10  would function in the same manner as described hereafter. In this regard the term “bearing housing” is to be interpreted to include a structure composed of multiple parts that are joined together to support a bearing and a shaft for rotation about a shaft axis. 
         [0021]    The ball bearing  16  contains a limited quantity of lubricating fluid or bearing oil in the cavities in and around the balls and bearing races for lubrication of the bearing. The non-contact sealing system  10  has a centrifugal pressurizing seal that is positioned adjacent the bearing  16  and serves the function of supplying and replenishing the lubricating fluid in the bearing as well as pumping and circulating the limited quantity of fluid through the bearings  16  and  18  when the shaft  12  and bearing are rotating. The sealing system may also include a non-contact sealing system that excludes contaminants from entering the bearings as shown in U.S. Pat. No. 6,170,832 to Ernst. The non-contact sealing system  10   a  adjacent the bearing  18  is a mirror image of the system  10 , has the same basic structure as the system  10 , and serves the same fluid pumping and replenishment functions for the bearings. Hence, only the structure and operation of the sealing system  10  with the bearings are described below. 
         [0022]      FIGS. 1 and 2  show the non-contact sealing system  10  with a centrifugal pressurizing seal comprised by a stator ring  30  and a rotor ring  32 . The stator ring  30  and the rotor ring  32  are positioned between the shaft  12  and the bearing housing  20  adjacent the outer side of the roller bearing  16 . If desired, a bushing  34  may be positioned on the shaft for a firm press fit between the rotor ring to the shaft and to insure that the rotor ring rotates with the shaft relative to the stator ring  30  and bearing housing  12 . The stator ring similarly has a press fit in the housing to insure that the stator ring remains stationary in the bearing housing. The stator ring and the rotor ring may be formed from stamped sheet metal fabrications which facilitate the press fit to the shaft and housing respectively. 
         [0023]    As shown most clearly in  FIGS. 3   a - 3   d,  the stator ring  30  is formed with an annular channel  34  that circumscribes the ring on one axially end face of the ring. When mounted next to a bearing, such as bearing  16 , the annular channel faces the bearing in the axial direction. A series of radially extending notches  36  reaching into the annular channel  34  are spaced circumaxially about the ring in the outer portion of the ring  30  and serve to deliver pressurized lubricating fluid from the non-contact seal to the bearings  16  and  18  as explained hereafter. 
         [0024]    The rotor ring  32 , illustrated in isolation in  FIG. 4 , is comprised of two stamped sheet metal annular parts  38  and  40 . The annular parts are pressed fit together as shown and form an annular centrifugal pumping chamber  42  that circumscribes the shaft axis  14 . When the rotor ring  32  is assembled with the stator ring  30  as shown in  FIGS. 1 and 2 , the pumping chamber  42  of the rotor ring is positioned in the annular channel  34  of the stator ring, and is in fluid communication with the bearings  16  and  18  through the annular channel  34  and the notches  36  of the stator ring  30 . 
         [0025]      FIG. 2  shows a series of annular pumping discs  46  positioned in the pumping chamber  42  and circumscribing the shaft axis  14 . The discs are free floating in the chamber and have dimples to maintain spacing between the discs. When the rotor ring  32  is rotated with a shaft  12 , lubricating fluid in the pumping chamber is centrifugally thrown radially outward toward the outer wall of the pumping chamber. In the process the discs serve the purpose of maintaining an orderly laminar flow of the lubricating fluid outwardly to develop a higher fluid pressure at the outer wall of the pumping chamber  42 . It is this pressure which is used to deliver the lubricating fluid to the bearings  16  and  18 . 
         [0026]    A series of discharge apertures  48  shown in  FIGS. 2 and 4  are circumaxially spaced about the part  40  of the rotor ring  32  at the outer periphery of the centrifugal pumping chamber  42  to allow the lubricating fluid pressurized in the chamber to be discharged into the annular channel  34  and notches  36  of the stator ring as shown by the arrows. From the notches, the pressurized lubricating fluid is ducted directly to the nearside of the bearing  16  and indirectly to the remote side of the bearing through channels  50 ,  52  in the bearing housing  20 . The channels  50 ,  52 , which form part of the sealing system, are distributed circumaxially in the bearing housing and are in fluid communication with the notches  36  by way of an annular groove  54  in the end of the housing. Of course the pressurized lubricating fluid can be ducted from the pressurizing chamber  42  to the bearing  16  by other channel designs in the bearing housing. 
         [0027]    It should be noted that the pressurized lubricating fluid from the pressure chamber  42  can be delivered by the channels  50  to the bearing  18  that is remote from the chamber, and pressurized lubricating fluid from the pressurizing chamber adjacent to the remote bearing  18  can be delivered to the bearing  16 . Hence the lubricating fluids for each bearing can be shared. 
         [0028]    It will be understood that the stator ring  30  and the rotor ring  32  preferably should maintain a fluid-tight relationship with the bearing housing  20  and the shaft  12  in order to prevent the lubricating fluid  22  from leaking out of the sealing system. Fill ports  56  are provided at the upper portion of the housing for filling and replenishing lubricating fluid in the system. However, when the shaft and rotor ring  32  are not rotating, the lubricating fluid will drain into the lower portion of the pressure chamber  42  and bearing housing  20 . When shaft rotation is resumed, the lubricating fluid will again be pumped from the centrifugal pumping chamber  42  back into the bearings through the notches  36  in the stator ring  30  and the channels  50 ,  52  in the bearing housing  20 . 
         [0029]      FIGS. 5 and 6  illustrate an embodiment of the non-contact sealing system employed with a vertically oriented shaft  12   a  supported by roller bearings  16   a  and  18   a  in a housing  20   a.  In the embodiment of  FIGS. 5 and 6 , parts corresponding to the parts in the embodiment of  FIGS. 1-4  bear the same reference numerals, and parts performing similar functions but with different or modified structure have the same reference numerals with a subscript “a” added. 
         [0030]    For purposes of illustration, the length of the shaft  12   a  and the housing  20   a  have been reduced in  FIG. 5 , and the roller bearings  16   a  and  18   a  are positioned adjacent one another rather than spaced from one another as would be the case with a longer shaft and housing. The principles of operation of the non-contact sealing system as described hereafter are the same regardless of the dimensional reductions. 
         [0031]    The non-contact sealing system in  FIGS. 5 and 6  for the vertically oriented shaft  12   a  includes a single centrifugal pressurizing seal formed by a stator ring  30   a  and a rotor ring  32   a  and held in the bearing housing  20   a  by a retaining ring  70  and bolts  72 . The rings  30   a  and  32   a  have substantially the same structure as the rings  30  and  32  of the embodiment in  FIGS. 1-4  and function in the same fashion, except the dimensions of the rings  30   a  and  32   a  in the vertical direction identified by the shaft axis  14   a  are larger to form a larger reservoir and pressurizing chamber  42   a  for the lubricating fluid when the shaft  12   a  is not rotating. Specifically, the dimensions of the pressurizing chamber  42   a  and the annular channel  34   a  in the stator ring in the axial direction are large enough to accommodate a volume of lubricating fluid that is needed to reach the remote sides of the bearings  16   a  and  18   a.    
         [0032]    The number of pumping discs  46   a  may also be increased to maintain laminar flow in the pressurizing chamber  42   a  during shaft rotation. In any event the pumping discs are located in the lower part of the pressurizing chamber to be certain that the discs are immersed in the lubricating fluid and aid in the pressurizing function. 
         [0033]    The bearing housing  20   a  supports the shaft  12   a  with a vertical orientation for rotation in the bearings  16   a  and  18   a.  The non-contact sealing system includes the stator ring  30   a  and rotor ring  32   a  positioned in the housing at the lower end of the shaft  12   a.  The system supplies pressurized lubricating fluid from the pressurization chamber  42   a  through the series of discharge ports  48  in the rotor ring  32   a  and the notches  36   a  in the stator ring  30   a  to multiple vertically extending, circumaxially spaced channels  50   a  in the housing  20   a,  as indicated by the arrows. 
         [0034]    At the upper side of the housing  20   a,  a fluid distribution ring  60  shown in isolation in  FIG. 7  captures the lubricating fluid, and directs the lubricating fluid onto the top of the bearing  18   a.  The fluid then drains down through the bearings  18   a  and  16   a  and returns to the pumping chamber  42   a  where the fluid can be re-pressurized and re-circulated through the bearings. 
         [0035]    The fluid distribution ring  60  shown in  FIGS. 5 and 7  performs several functions. As shown in  FIG. 5 , the ring is annular and is press fit into the upper end of the bearing housing  20   a  to produce a fluid tight relationship with the housing. The ring  60  has an annular outside groove  62  which registers with the channels  50   a  of the bearing housing and in this manner receives the pressurized lubricating fluid from pumping chamber  42   a.  The annular groove  62  in the ring extends around the outer side of the ring and has multiple discharge ports  64 , for example, four equally spaced holes, in the base of the groove to distribute and discharge the lubricating fluid over the bearings. 
         [0036]    In addition to being pressfit into the upper end of the bearing housing  20   a,  the discharge ring  60  is clamped against the outer race of the bearing  18   a  by means of a coverplate  66  and clamping bolts  68  extending into the housing. Thus the discharge ring retains the bearing  18   a  in the bearing housing. If necessary a sealing compound may be added between the coverplate and the housing. 
         [0037]    In operation, the rotation of the shaft  12   a  and the rotor ring  32   a  on the shaft causes the lubricating fluid to be pressurized by centrifugal force in the pressure chamber  42   a  and discharged into the lower bearing  16   a  directly and into the upper bearing  18   a  through the channels  50   a  and distribution ring  60 . The lubricating fluid drains down through the bearings by gravity, and can again be circulated through the bearings. When shaft rotation stops, all the lubricating fluid returns to the reservoir formed by the pressurization chamber and annular channel  34   a  within the stator ring  30   a,  and forms a seal to keep contaminants out of the sealing system. 
         [0038]    While the present invention has been described in several embodiments, it will be understood that other variations and modifications can be made without departing from the spirit of the invention. For example, although the bearing housings have been illustrated as one piece, the housing can be formed as multi-piece structures with continuous channels leading between the pieces. The rotor ring has been described as being formed by stamped sheet metal parts, but can be formed by other methods. Accordingly, the non-contact sealing system has been described by way of illustration rather than limitation.