Abstract:
A labyrinth sealing device is disclosed for use between a rotating shaft and a bearing housing. In some embodiments, an internal stator engages the housing and a rotor engages the shaft. A labyrinth pathway is defined between the rotor and stator to prevent the migration of lubricants and/or contaminants in either direction. The rotor acts as a running surface for the sealing element, but may also with a ground surface of the rotor to provide a pump that continuously draws lubricant away from the sealing lip toward a sump. In another embodiment, the stator and sealing element are combined as a single element formed from a sealing material. A recess in the sealing lip creates a pressure differential at the sealing surface and minimizes wear.

Description:
This application claims priority to U.S. Provisional Patent Application No. 61/260,282, filed Nov. 11, 2009, and U.S. Provisional Patent Application No. 61/350,371, filed Jun. 1, 2010, both of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Labyrinth sealing devices are commonly used to provide a dynamic seal between a rotating shaft and a bearing housing. The sealing device excludes contaminates from the bearing housing while also preventing loss of bearing lubricants. In some applications, the lubrication level of the housing is above the lowest point of the seal. Commonly, the lubrication will eventually work through the seal and leak, where a non-contact seal is used. A contact type seal is desirable in such applications. 
     In a typical rotor and stator configuration, it is important to keep the rotor and stator from contacting one another. The rotor spins at very high speeds. If a surface of the rotor contacts a surface of the stator at these speeds, frictional heat develops, the parts wear and the overall efficiency of the apparatus declines. It is, therefore, important to keep the rotor and stator separate. The seal between the rotor and stator keeps them separate in the radial direction by providing a low friction contact between the two. It would be beneficial if the same seal could also prevent contact in the axial direction. 
     A further problem occurs when the housing is “flooded” with lubricant. A flooded housing refers to a bearing cavity with an excess of lubricant, thus “flooded”. Traditional non-contacting seals do not function properly if used in a flooded housing. 
     Various seal devices have been previously developed to provide a dynamic seal between rotating shafts and a bearing housing. However, these previous designs have not resolved all of the operational issues experienced with these types of seals. For example, U.S. Pat. No. 6,234,489 to Orlowski et al. discloses a seal that includes a rotor and a stator. Enclosed within the rotor and stator is an insert that has an annular resilient member to hold one side of the insert in firm contact with an outer radial surface of the rotor. The shortcoming of this design is that, in its preferred configuration, the annular resilient member is provided as an o-ring. 
     Another seal design, disclosed within U.S. Pat. No. 6,386,546 to Fedorovich, includes a rotor and stator that are arranged to create a labyrinth portion and a contact portion. The stator includes one or more flanges biased toward the rotor surface to create the contact portion of the seal. The inherent problem with this type of seal is that the lay-down lip or flange biased toward the rotor cannot handle misalignment. Once the seal is misaligned, the lip gets flexed to one side of the seal and is then permanently deformed. Lubrication can then leak under the sealing lip if the misalignment is removed. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary, and the foregoing Background, is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter. 
     A labyrinth sealing device is disclosed herein that, in many embodiments, is used between a rotating shaft and a bearing housing. In such embodiments, the design will include an internal stator that engages the housing and a rotor that engages the shaft. A labyrinth pathway is defined between the rotor and stator to prevent the migration of lubricants and/or contaminates in either direction. In some embodiments, the rotor acts as a running surface for the sealing element, but may also serve as a pump that continuously draws lubricant away from the sealing lip toward a sump. 
     In some embodiments, the stator mates with a sealing element, which also acts as a unitizing feature for the rotor and stator components. In such embodiments, a lip seal may serve as a standard lip seal with contact at the rotor. The sealing lip can be provided with a flat interface where it contacts the rotor. A portion of the sealing element interface will contact the smooth surface of the rotor while the remaining flat area of the sealing element will be suspended over a helical pumping feature on the rotor. 
     Various embodiments of the seal device are based on a uniquely shaped lip seal, which may be formed from PTFE, and a specifically placed pumping feature. The flat of the sealing element and the flat of the rotor will seal when static, but a helical pumping feature under the remaining portion of the seal flat will draw lubricant away from the seal lip. 
     In another embodiment, the stator and sealing element are provided as a single element, or sealing stator, which may be formed from a sealing material. A lip seal is provided to sealingly engage a running surface of the rotor. However, the sealing surface interface portion of the lip seal is provided with a recess that creates a pressure differential at the sealing surface interface portion. This limits the passage of fluid and debris while limiting wear. In such embodiments, the sealing stator includes a protrusion that extends from a radially outwardly positioned flange. The protrusion may be press fit past a mating nodule that extends outwardly from an outer edge of the rotor. Once the rotor and sealing stator are placed in a position where, the protrusion and mating nodule engage one another, one or more ridges or wear beads may be positioned along a lower surface of the sealing stator to engage the rotor, whereby minimal frictional engagement is attained between the rotor and the sealing stator. 
     In another embodiment, the sealing stator and rotor are positioned to form a labyrinth-type passage between the sealing stator and rotor that aids in preventing the migration of lubricants and/or contaminants in either direction. The rotor includes a flange that protrudes toward the sealing stator and occupies a space above the lip seal of the sealing stator and below the radial outer surface of the sealing stator. The sealing stator further includes an arm on the axial inward side of the assembly that extends radially towards the rotor. At the end of the arm, a face type lip protrudes axially towards the rotor and contacts the rotor to create a seal at one end of the labyrinth passage through the assembly. The arm can be biased axially towards the rotor such that the face type lip creates a tight seal. The assembly of this embodiment can optionally include features from previously described assemblies, such as the recess in the sealing surface interface portion of the lip seal and the protrusion and mating nodule. 
     These and other aspects of the present system and method will be apparent after consideration of the Detailed Description and Figures herein. It is to be understood, however, that the scope of the invention shall be determined by the claims as issued and not by whether given subject matter addresses any, or all issues noted in the Background or includes any features or aspects recited in this Summary. 
    
    
     
       DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
         FIG. 1  depicts a partial, cut-away view of one embodiment of a flooded seal assembly. 
         FIG. 2  depicts a partial, cut-away view of one embodiment of a sealing contact portion of the flooded seal assembly depicted in  FIG. 1 . 
         FIG. 3A  depicts a partial, cut-away view of another embodiment of a flooded seal assembly. 
         FIG. 3B  depicts a partial, cut-away view of one embodiment of a sealing contact portion of the flooded seal assembly depicted in  FIG. 3A . 
         FIG. 3C  depicts a partial, cut-away view of another embodiment of a flooded seal assembly. 
         FIG. 4  depicts a partial, cut-away view of another embodiment of a flooded seal assembly. 
         FIG. 5  depicts a partial, cut-away view of another embodiment of a flooded seal assembly. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are described more fully below with reference to the accompanying figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense. 
     With reference to  FIG. 1 , a labyrinth sealing device  10  is provided, in various embodiments, to provide a dynamic seal between a rotating shaft and a bearing housing. Accordingly, embodiments of the sealing device  10  will serve to prevent the leakage of lubricant from the bearing housing and the entry of contaminates into the housing. The sealing device  10  will generally include a rotor  12  that is placed in sealing engagement with the shaft (not depicted) by one or more o-rings  14 . It is contemplated that the rotor will be formed from stainless steel, bronze or other material that is suitable for use with the intended purpose of the overall assembly in which the sealing device  10  is used. Likewise, the o-rings  14  may be provided in various materials commonly used in similar applications. In various embodiments, the rotor  12  will include an annular flange  16 , which provides a running surface  18 . As will be discussed in greater detail below, the running surface  18  of the annular flange  16  may be provided with a relatively smooth or modeled surface, or a combination thereof, to provide one or more desired attributes to the sealing device  10 . 
     The sealing device  10  will further include a stator  20 , which may be formed from bronze or other material known to be suitable for similar labyrinth sealing devices. In various embodiments, the stator  20  is coupled with a sealing element  22 . In some embodiments, the stator  20  and sealing element  22  will be coupled with one another with a snap ring  24  that is press-fit adjacent an anti-rotation pin  26 . It is contemplated that the snap ring  24  and anti-rotation pin  26  could be formed from steel or other similar material capable of coupling the stator  20  and sealing element  22  with one another throughout contemplated uses and the forces generated during such uses. Adjacent the anti-rotation pin  26 , the stator  20  and sealing element  22  may be positioned to mate together with an o-ring  28  that is press-fit to create a static seal area  30 . On its opposite surface, the stator  20  will be placed in sealing engagement with the bearing housing with an o-ring  32 . The o-rings  28  and  32  may be provided in a similar construction and of similar materials to the o-ring  14 . However, it is contemplated that various intended uses of the seal device  10  may require the use of additional or fewer o-rings or o-rings of different construction. 
     With reference to  FIG. 2 , some embodiments of the sealing device  10  will be provided with a lip seal  34  that extends inwardly from an axially outward position on the sealing element  22 . The lip seal  34  may, in some embodiments, be provided with a unitizing feature as well as a flat sealing surface interface portion  36 . In such embodiments, at least a portion of the sealing surface interface portion  36  rides against the flat portion of the rotor surface  18   a . In some embodiments, the lip seal  34  will be biased radially inwardly to some degree to apply at least some pressure, for sealing engagement, when the lip seal  34  is placed against the rotor surface  18 . It is contemplated that the seal element  22  may be formed from PTFE or other similar materials in order to provide the desired sealing characteristics as well as a resiliently deformable nature that may be desirable in the construction and use of labyrinth seal devices. The remaining or distal end portion of the sealing surface interface  36  is suspended over a helical pumping feature  38  on the rotor surface  18   b  when the lip seal is placed in its use position against the rotor surface  18 . 
     In various embodiments, the helical pumping feature  38  may be provided by forming a generally helically shaped groove around the rotor surface  18   b . It is contemplated that the groove may be formed through various molding or casting techniques as well as grinding or removing portions of the rotor surface  18   b  using known tooling equipment designed for such purposes. With the lip seal  34  riding on the rotor surface, the helical feature will continuously pull lubricant away from the sealing element  22  but allow the seal element  22  to seal lubricant in while the seal device  10  is static. If axial motion occurs, the lip seal  34  will remain in its critical location on the rotor, due to the unitizing feature, and continue to seal. Accordingly, it is contemplated that different groove patterns and configurations that are more or less helical, or assume different patterns, including sine waves, circular elements and other geometric shapes may be selected for their ability to draw fluid material away from a given area as the structure rotates. 
     Some embodiments of the sealing element  22  include a protrusion  40  that extends from the sealing element  22  on a side opposite the lip seal  34 . The protrusion  40  may be provided with an angled, barb-shape, such as depicted in  FIG. 1 . In this manner, the protrusion  40  may be press fit past a mating nodule  42  that extends outwardly from the rotor surface  18 , with angled surfaces of the opposing structures sliding past one another. The shapes of the protrusion  40  and mating nodule may be provided with flattened or reverse angle surfaces to engage one another and prevent the unintentional removal of the sealing element  22  from the rotor  18 . In this manner, metal-to-metal contact of the rotor  12  and stator  20  may be significantly limited. 
     It will become apparent, after a review of the design of the seal device  10 , that a number of prior art failings have been successfully addressed. In particular, the o-ring design of other devices, which do not hold their resiliency during any period of shaft to bore misalignment, is resolved with the present design. The seal device  10  prevents the seal from separating from the rotor. Moreover, the design of the seal device  10  prevents the seal element  22  from separating from the rotor  18 , as is experienced frequently in the prior art. These benefits are accomplished, at least in part, by fixing the seal element  22  to the stationary portions of the seal device  10  by means of the flange  16 , and allowing the lip seal  34  to float in the radial direction. 
     With reference to  FIGS. 3A and 3B , a labyrinth sealing device  100  is provided as one alternate embodiment to sealing device  10 . Various embodiments of the sealing device  100  may be employed to provide a dynamic seal between a rotating shaft and a bearing housing. The sealing device  100  includes a rotor  112  that is placed in sealing engagement with the shaft (not depicted) by one or more o-rings  114 . The rotor  112  may be formed from stainless steel, bronze or other material that is suitable for use with the intended purpose of the overall assembly in which the sealing device  100  is used. Similarly, the o-rings  114  may be provided in various materials commonly used in such applications. In various embodiments, the rotor  112  will include an annular flange  116 , which provides a running surface  118 . 
     Embodiments of the sealing device  100  will further include a stator and a sealing element. In some embodiments, the stator and sealing element may be formed in unitary construction to provide a sealing stator  120  which may be formed from PTFE, teflon or other material known to be suitable for similar labyrinth sealing devices. In various embodiments, the material that is used to form the sealing stator  120  will provide low-friction, low-wear, and sealing characteristics desired for the particular uses intended. On its radially outwardly faced surface, the sealing stator  120  will be placed in sealing engagement with the bearing housing with an o-ring  122 , which may be provided in a similar construction and of similar materials to the o-ring  114 . However, it is contemplated that various intended uses of the sealing device  100  may require the use of additional or fewer o-rings or o-rings of different construction. 
     With further reference to  FIGS. 3A and 3B , some embodiments of the sealing stator  120  will include a lip seal  124  that extends in an axially inward direction. The lip seal  124  may, in some embodiments, be provided with a unitizing feature as well as a flat sealing surface interface portion  126 . In such embodiments, at least a portion of the sealing surface interface portion  126  rides against the flat portion of the running surface  118 . In some embodiments, the lip seal  124  will be biased inwardly to some degree to apply at least some pressure, for sealing engagement, when the lip seal  124  is placed against the running surface  118 , which may be provided in a smooth or ground running surface  118 . When the lip seal  124  is biased, the lip seal includes a hinge point  124   a . The hinge point can have a thickness T shown in  FIG. 3A . Any suitable thickness T can be used. In some embodiments, the thickness can range from 0.010 to 0.150. 
     As seen in  FIG. 3A , a portion of the radial inner surface of the lip seal  124  is angled. This angled surface  125  extends from the sealing surface interface portion  126  up away from the running surface  118 . An angle A is formed at the contact point between the angled surface  125  and the running surface  118 . Any suitable angle A can be used. In some embodiments, the angle A can range from 10° to 45°. Adjustments to the angle A and thickness T can alter the length L between the hinge point  124   a  and the first contact point between the sealing surface interface portion  126  and the running surface  118 . 
     In some embodiments, a radially-oriented protrusion  129  may be included at the end of the lip seal  124  to create an additional seal between the rotor  112  and the sealing stator  120 . As shown in  FIG. 3C , the radially-oriented protrusion  129  is deflected by the running surface  118  of the rotor  112  when the rotor  112  is mated with the sealing stator  120 . The radially-oriented protrusion  129  can be biased in an axially outward direction to better effect the seal between the rotor  112  and the sealing stator  120 . As also seen in  FIG. 3C , a gap may exist between the end of the sealing surface interface portion  126  and the radially-oriented protrusion  129 . The length of the sealing stator interface portion  118  can be altered to accommodate for the inclusion of the radially-oriented protrusion  129 . 
     in various embodiments, the sealing surface interface portion  126  will include one or more recesses  128 . In some embodiments, the one or more recesses  128  may be positioned intermediate opposite ends of the sealing surface interface portion  126 , while in other embodiments, the one or more recesses  128  may be positioned closer or immediately adjacent one or the opposite ends of the sealing surface interface portion  126 . In any such embodiment, the one or more recesses  128  creates a pressure differential that allows the sealing surface interface portion  126  to ride on the running surface  118  without experiencing undue wear or allowing the passage of fluids or debris to pass the lip seal  124 . The length of the sealing surface interface portion  118  can be increased to accommodate additional recesses  128 . 
     Some embodiments of the sealing stator  120  include a protrusion  130  that extends from an axially outwardly positioned flange, although this protrusion  130  is not required for sealing performance. The protrusion  130  may be provided with an angled, barb-shape, such as depicted in  FIG. 3A . In this manner, the protrusion  130  may be press fit past a mating nodule  132  that extends outwardly from an outer edge of the rotor  112 , with angled surfaces of the opposing structures sliding past one another. The shapes of the protrusion  130  and mating nodule  132  may be provided with flattened or reverse angle surfaces to engage one another and prevent the unintentional removal of the sealing stator  120  from the rotor  112 . The gap between the mating nodule  132  and the protrusion  130  can be varied to allow for more or less axial movement of the rotor  112 . Once the rotor  112  and sealing stator  120  are placed in a position where the protrusion  130  and mating nodule  132  engage one another, one or more ridges or wear beads  134  may be positioned along a lower surface of the sealing stator  120  to engage the rotor  112 . Conversely, or in combination with, the ridges or wear beads  134  can also protrude from the surface of the rotor  112  and engage the sealing stator  120 . In such embodiments, minimal frictional engagement is attained between the rotor  112  and the sealing stator  120 . 
     With reference to  FIG. 4 , a labyrinth sealing device  200  is provided as another alternate embodiment to sealing device  10 . Various embodiments of the sealing device  200  may be employed to provide a dynamic seal between a rotating shaft and a bearing housing. The, sealing device  200  includes a rotor  212  that is placed in sealing engagement with the shaft (not depicted) by one or more o-rings  214 . The rotor  212  may be formed from stainless steel, bronze or other material that is suitable for use with the intended purpose of the overall assembly in which the sealing device  200  is used. Similarly, the o-rings  214  may be provided in various materials commonly used in such applications. In various embodiments, the rotor  212  will include an annular flange  216  that is aligned in an axial direction, which provides a running surface  218 . The rotor  212  can also include a radial portion  215 , which is sometimes referred to as a radially-oriented base portion  215 , that helps form an enclosed space between the rotor  212  and the sealing stator  220  described in greater detail below. 
     Embodiments of the sealing device  200  will further include a sealing stator  220  which may be formed from PTFE, teflon or other material known to be suitable for similar labyrinth sealing devices. In various embodiments, the material that is used to form the sealing stator  220  will provide low-friction, low-wear, and sealing characteristics desired for the particular uses intended. On its radially outwardly faced surface, the sealing stator  220  will be placed in sealing engagement with the bearing housing with an o-ring  222 , which may be provided in a similar construction and of similar materials to the o-ring  214 . However, it is contemplated that various intended uses of the sealing device  200  may require the use of additional or fewer o-rings or o-rings of different construction. As can be seen in  FIG. 4 , when the sealing stator  220  and the rotor  212  are brought together, a labyrinth passage  217  is formed. The labyrinth passage includes turns and bends that cause turbulence within the labyrinth passage  217  and thereby makes the passage of lubricant or contaminants through the labyrinth passage  217  more difficult. 
     Some embodiments of the sealing device  200  illustrated in  FIG. 4  will include a lip seal  224  that extends axially outwardly from the sealing stator  220  and towards the rotor  212 . The lip seal  224  may, in some embodiments, be provided with a unitizing feature as well as a flat sealing surface interface portion  226 . As shown in  FIG. 4 , the entirety of the sealing surface interface portion  226  rides against the running surface  218 . In some embodiments, the lip seal  224  will be biased radially inwardly towards the rotor  212  to some degree to apply at least some pressure, for sealing engagement, when the lip seal  224  is placed against the running surface  218 . 
     In some embodiments, the sealing stator  220  includes an arm  230  that extends radially towards the rotor  212 . The arm  230  can extend in a radial direction towards the rotor  212  until at least a portion of the arm  230  overlaps with the annular flange  216  of the rotor  212 . In some embodiments, the end of the arm  230  is substantially even with the radially inner surface of the annular flange  216 . The end of the arm  230  includes a face type lip  232  that protrudes away from the arm  230  in an axially outward direction (i.e., towards the annular flange  216  of the rotor  212 ). The face type lip  232  contacts the annular flange  216  and creates a sealing that can prevent lubricant and/or contaminants from passing in or out of the labyrinth passage  217  formed between the sealing stator  220  and the rotor  212 . The annular flange  216  seals at a lower pressure when lubricant is kept from passing into the labyrinth passage  217  at the annular flange  216 , thus making the seal formed by the face type lip  232  beneficial. 
     The arm  230  can be biased in a axially outward direction in order to form a stronger seal between the face type lip  232  and the annular flange  216 . The face type lip  232  preferably has a square shape such that the contacting surfaces of the annular flange  216  and the face type lip  232  are aligned in parallel, although other shapes can be used for the face type lip  232  including shapes that may form a point or line contact rather than a surface contact. 
     The pressure loading of the face type lip  232  against the annular flange  216  can be set at a predetermined value using a square ridge  234  that protrudes axially outward from the sealing stator  220  towards the rotor  212 . As shown in  FIG. 4 , the square ridge  234  is located within the labyrinth passage  217  towards the radially outer surface of the sealing stator  220 . When the sealing stator  220  is paired with the rotor  212 , the square ridge  234  dictates how closely the sealing stator  220  and the rotor  212  come together. The length of the square ridge  234  ensures that the sealing stator  220  and the rotor are brought together closely enough to ensure the arm  230  is flexed against its bias and a firm interference seal is formed between the face type lip  232  and the annular flange  216 . Additionally, the square ridge  234  ensures that the sealing stator  220  and the rotor  216  are not brought together so closely that the arm  230  overflexes against its bias and possibly causes the arm  230  to snap off of the sealing stator  220  (thereby forming no seal at all at the annular flange  216 ). Furthermore, the square ridge  232  further builds the labyrinth passage  217  and makes it more difficult for contaminants and/or lubricant to pass through the labyrinth passage  217 . 
     The rotor  212  can further include a flange  236  that protrudes axially inwardly from the radial portion  215  of the rotor  212 . The flange  236  is positioned on the radial portion  215  such that the flange  236  extends into a space formed between the lip seal  224  and the radially outer surface of the sealing stator  220 . In this manner, the flange  236  results in a complex labyrinth passage  217 . The flange  236  results in the formation of more turbulence within the labyrinth passage  217  while also increasing the pressure on the outboard side. Because the pressure on the outboard side is typically lower compared to the inboard side, this increase in pressure beneficially reduces the pressure between the outboard side and the inboard side. 
     As shown in  FIG. 5 , the labyrinth sealing device  200  can include one or more of the features included in the labyrinth sealing device  100  shown in  FIGS. 3A and 3B . For example, the labyrinth sealing device  200  can include a lip seal  224  having a recess  228 , and can also include a protrusion  240  and mating nodule  242  to ensure the sealing stator  220  and the rotor remain mated to one another. The combination of these features together with the face type lip  232 , the square ridge  234 , and the flange  236  can result in a labyrinth sealing device well suited for preventing the migration of lubricant and/or contaminants through the labyrinth passage  217 . 
     Although the sealing devices  10 ,  100 , and  200  have been described in language that is specific to certain structures, materials, and methodological steps, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific structures, materials, and/or steps described. Rather, the specific aspects and steps are described as forms of implementing the claimed invention. Since many embodiments of the invention can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. Unless otherwise indicated, all numbers or expressions, such as those expressing dimensions, physical characteristics, etc. used in the specification (other than the claims) are understood as modified in all instances by the term “approximately.” At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the claims, each numerical parameter recited in the specification or claims which is modified by the term “approximately” should at least be construed in light of the number of recited significant digits and by applying ordinary rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass and provide support for claims that recite any and all subranges or any and all individual values subsumed therein. For example, a stated range of 1 to 10 should be considered to include and provide support for claims that recite any and all subranges or individual values that are between and/or inclusive of the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to 3.56, and so forth) or any values from 1 to 10 (e.g., 3, 5.8, 9.9994, and so forth).