Abstract:
An isolator sealing device includes a stator, which locates into a housing of a piece of rotating equipment, and a rotor which radially locates onto a rotary shaft of the piece of rotating equipment. The rotor and stator have one or more adjacent surfaces facing a labyrinth seal and a lip seal which sealingly engages the stator or the rotor when the equipment is idle and sealingly disengages the stator or the rotor when the equipment is operational.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to isolator sealing devices and particularly to non-contacting seals protectors and their use in rotating equipment. Such devices prevent the ingress or egress of a fluid or solid to a cavity, resulting in deterioration of equipment life. 
         [0002]    Such devices are often referred to as bearing protectors, bearing seals or bearing isolators. However, seals of the present invention may be used for applications other than the protection of bearings. Accordingly, while reference below may be to bearing protectors, it should be understood that the invention may have wider uses. 
       BACKGROUND TO THE INVENTION 
       [0003]    The purpose of a bearing protector is to prevent the ingress of fluid, solids and/or debris from entering a bearing chamber. Equally, bearing protectors are employed to prevent the egress of fluid or solids from a bearing chamber. Essentially, their purpose is to prevent the premature failure of the bearing. 
         [0004]    Bearing protectors generally fall into two categories: repeller or labyrinth bearing protectors; and mechanical seal bearing protectors. Reference is made to our co-pending labyrinth seal bearing protection application GB0415548.7 which defines a substantially non-contacting bearing protector with static shut off device. 
         [0005]    The rotating component typically has a complex outer profile which is located adjacent and in close radial and axial proximity to a complex inner profile of the stationary component. Together these complex profiles, in theory, provide a tortuous path preventing the passage of the unwanted materials or fluids. 
         [0006]    Conventional labyrinth technology indicates the said close radial counter rotational members are substantially parallel to each other and run parallel to the centreline of the shaft. Given that the fundamentals of the design is that the rotor and stator are non-contacting, it will not hold a level of bearing lubricant which is greater than the smallest radial position between the rotor and stator. Unfortunately, operators occasionally overfill bearing chambers with lubricant, meaning that in certain cases the lubricant runs out of the labyrinth seal and onto the surrounding work area. 
         [0007]    Also, during installation, some types of rotating equipment are not perfectly aligned in the horizontal axis. Given that the bearing lubricant will always sit perfectly on the horizontal axis inside the bearing chamber, if the rotating equipment bearing chamber is misaligned to the horizontal axis, the bearing lubricant will be higher at one side of the bearing chamber than at the other side. Once again, this can cause the lubricant to run through the labyrinth clearances specifically when the equipment is in the static condition. When the equipment is in the dynamic condition, centrifugal forces and/or the complex geometries of the labyrinth and lubricant velocity reducing cavities can sufficiently discourage lubricant egress, even when the equipment is slightly misaligned. 
         [0008]    Orlowski U.S. Pat. No. 6,234,489 teaches a bearing isolator with an integral lipseal with energising member, item  25 , which apparently applies a radial force to the sealing member lip thereby helping to maintaining radial sealing contact a seal between the stationary lipseal and rotor member. 
         [0009]    In essence, Orlowski U.S. Pat. No. 6,234,489 teaches a contacting bearing isolator, which gives rise to a whole host of additional issues compared a non-contacting isolator, such as high lipseal wear, high heat generation and increase equipment energy consumption. 
         [0010]    A preferred non-contacting labyrinth-type seal bearing protector will effectively seal high lubricant levels, specifically when the equipment is static and is misaligned. Such a sealing device desirably also acts as a non-contacting device when the equipment is operational. 
       STATEMENTS OF THE INVENTION 
       [0011]    According to the present invention there is provided a non-contacting sealing device comprising a stator which is rotationally coupled to the housing of an item of rotating equipment and a rotor which is rotationally coupled to the rotor of an item of rotating equipment, said rotor and stator having one or more radial and/or axial adjacent surfaces forming a labyrinth seal, and a lip-type seal which sealingly engages the stator when the equipment is idle and sealingly disengages the stator when the equipment is operational. 
         [0012]    Preferably, the device incorporates an external shut off device which provides a non-contacting seal when the equipment is operational and a contacting seal when the equipment is static, thereby preventing moisture ingress during equipment cool down periods. 
         [0013]    Preferably the lip-type sealing member sealingly engages the stator on a substantially male cylindrical portion of said stator. 
         [0014]    Preferably, the lip-type seal includes a lip which is structured for sealing engagement when the equipment is stationary and for disengagement at low rotational speeds. 
         [0015]    Preferably, a second sealing device, termed a shut-off valve, is positioned on the atmospheric side of the device, said shut-off valve engaging the stator or rotor when the equipment is idle and sealingly disengaging the stator or rotor when the equipment is operational. The shut-off valve may include a solid toroidal member. 
         [0016]    Preferably, the device includes at least one deformable toroidal member providing sealing between the equipment housing the stator. 
         [0017]    Preferably, the device includes at least one deformable torroidal member providing sealing between the equipment shaft the rotor. 
         [0018]    Preferably, the lipseal comprises a body portion abutting the radially inner surface of a longitudinal flange of the rotor. 
         [0019]    Preferably the lip of the lipseal extends radially inwardly from said body portion into engagement, when the equipment is stationary, with a longitudinal flange of the stator. 
         [0020]    Preferably, the lip has a first portion extending from the body portion of the lipseal towards the flange of the stator and a second portion extending from said first portion to a position between the flange of the stator and said body portion. 
         [0021]    Preferably, the lipseal is of substantially V-shaped cross-section. 
         [0022]    Preferably, the second portion is provided with an enlarged end portion. 
         [0023]    Preferably, the lip is integral with and made of the same material as that of the main part of the body portion. Also preferred is an arrangement in which the lip is formed of at least two parts, a first part being integral with and made of the same material as that of the main part of the body portion and a second part being formed of a denser material. More preferably, the denser material is a metal band. 
         [0024]    In a device of the present invention, the lipseal acts, under static conditions, as a normal lipseal, that is to say, providing a sealing function. Under the dynamic conditions, the lip lifts, that is to say, the seal disengages, thereby reducing wear on the lip of the lipseal. 
         [0025]    When a device of the invention incorporates both a lipseal and a mechanical shut off valve. The latter only prevents so-called chamber breathing. A flooded environment may be created at one or both ends of a bearing, for example, during transit of the equipment when it is not transported in a horizontal condition. The lipseal provides sealing against escape of oil which might cause premature failure of the bearing. 
         [0026]    Embodiments of labyrinth seals in accordance with the present invention may be in substantially cartridgised form whereby the rotor and stator are longitudinally coupled, or substantially non-cartridgised. 
         [0027]    Furthermore, in a preferred embodiment the labyrinth seal stator is provided with a substantially radial cavity adjacent to the rotor and/or equipment shaft. The radial cavity is discontinued at the 6 o&#39;clock position (viewing from a longitudinal end) permitting any lubricant/oil gathered in the cavity to drain back into the equipment bearing chamber. 
         [0028]    Preferably, the stator has a sealing member to sealingly engage the stator of the rotating equipment. 
         [0029]    Preferably, the rotor has a sealing member to sealingly engage the rotor of the rotating equipment. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0030]    The accompanying drawings are as follows: 
           [0031]      FIG. 1  is a partial longitudinal section of a first embodiment of a labyrinth seal bearing protector of the invention mounted on a shaft; 
           [0032]      FIG. 2  is a partial longitudinal section of a second embodiment of a labyrinth seal bearing protector of the invention mounted on a shaft. 
           [0033]      FIG. 3  is a partial longitudinal section of a third embodiment of a bearing protector of the invention mounted on a shaft; 
           [0034]      FIG. 4  is a partial longitudinal section of fourth embodiment of a labyrinth seal bearing protector of the invention mounted on a shaft; 
           [0035]      FIG. 5  is a partial longitudinal section of a fifth embodiment of a labyrinth seal bearing protector on the invention mounted on a shaft; 
           [0036]      FIG. 6  is a partial longitudinal section of a sixth embodiment of a labyrinth seal bearing protection of the invention mounted on a shaft; and 
           [0037]      FIG. 7  is a partial longitudinal section of the seventh embodiment of a labyrinth seal bearing protector of the invention mounted on a shaft 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    The invention will now be described, by way of example only, with reference to the accompanying drawings. 
         [0039]    In general, rotary seals in accordance with the present invention may be used not only in the case where the shaft is a rotary member and the housing is a stationary member but also the reverse situation, that is to say, in which the shaft is stationary and the housing is rotary. 
         [0040]    Furthermore, the invention may be embodied in both rotary and stationary arrangements, cartridge and component seals with metallic components as well as non-metallic components. 
         [0041]    Furthermore, the invention may be embodied when the rotary and/or the stationary are circumferentially solid, or when either or both of the members are radially split. 
         [0042]    Referring to  FIG. 1  of the accompanying drawings, a first embodiment of the invention is a bearing protector assembly  10  which is fitted to an item of rotating equipment  11 . The equipment includes a rotating shaft  12  and a stationary housing  13 . The stationary housing  13  could typically contain a bearing, which is not illustrated. 
         [0043]    Area “X” at one axial end of the bearing protector assembly  10  could partially contain fluid and/or solids and/or foreign debris and/or atmosphere. However for clarity it will herein be termed “product substance”, being used to describe a single or mixed medium. 
         [0044]    Area “Y” at the other axial end of the bearing protector assembly  10  could also partially contain fluid and/or solids and/or foreign debris and/or atmosphere. However, for clarity it will herein be termed “atmospheric substance”, being used to describe a single or mixed medium. 
         [0045]    The bearing protector assembly  10  includes a rotor member  14 , which is radially and axially adjacent to stator member  15 . 
         [0046]    A housing elastomer  16  provides a radial seal between the housing  13  and stator  15 . A shaft elastomer  17  provides a radial seal between the shaft  12  and rotor  14 . 
         [0047]    A static shut off device  18  is described in our co-pending labyrinth seal bearing protection application GB0415548.7 and will not be further described. 
         [0048]    A lip-type seal  19  is radially positioned in a cavity of the rotor  14  and is sealingly engaged to said rotor  14  by elastomer  20 . 
         [0049]    Said lip-type seal  19  preferably sealingly engages the stator  15  on a substantially cylindrical surface  22 . 
         [0050]    Stator  15  has a radially extending cavity  23  positioned adjacent to the rotating member of either the equipment (shaft  12 ) or rotor  14 . Said stator circumferential surface is discontinued at the 6 o&#39;clock position, viewed from the end, whereby the innermost surfaces  24  of the radial groove  23  communicate with the innermost sections of the equipment bearing chamber  25 . 
         [0051]    Preferably, the rotor  14  is longitudinally coupled to said stator  15  by face shield  26 , thereby cartridgising the assembly for ease of installation purposes. 
         [0052]    Shown, for reference only, is an optional drive ring collar  27 , which permits the rotor members of the labyrinth seal  10  to be positively driven by one or more screw members  28  to the shaft  12 . The drive collar  27  also prevents the rotor from “walking” longitudinally down the shaft in equipment vibration conditions. 
         [0053]    In the event that the equipment is idle, the shut off valve  18  prevents moisture being sucked from the atmospheric side “Y” of the bearing chamber into the seal cavity  30 . 
         [0054]    Furthermore, in the event that the equipment is idle, the lip-type seal  19  prevents bearing lubricant, namely oil, from being displaced into said cavity  30  and/or to atmosphere, in lubricant overfill or equipment misaligned conditions. 
         [0055]    When the equipment is operational, because the lip-type  19  sealing member is rotational and coupled with the rotor  14 , it is subject to centrifugal forces. Said centrifugal forces act to throw the lip-type seal  19  radially outwardly and away from sealing engagement at area  22  with the stator. 
         [0056]    Preferably, this creates a non-contacting seal at area  22 . However, equally preferably it reduces the sealing forces imparted by the lip-type seal  19  on the stator  15  therefore extending the sealing ability of said lip-type seal and reducing equipment power consumption. 
         [0057]      FIG. 2  shows an alternative embodiment of the invention  40 , showing the lip-type seal  41  rotationally coupled to the stator member  42  with a radial sealing interface on a substantially cylindrical portion of the rotor  43 . 
         [0058]      FIGS. 3 to 7  illustrate variations of the embodiment shown in  FIG. 1 . In the  FIG. 3  embodiment, the lip  51  of lipseal  53  differs from the embodiment shown in  FIG. 1  in that, instead of a simple angled flange, the lip includes a radially outwardly extending end portion  55 . This adds mass to the end of the lip and promotes its lift from the sealing position shown in  FIG. 3  when the equipment is rotating. 
         [0059]    In the embodiment shown in  FIG. 4 , the lip extension  61  is angled as illustrated and is longer than the extension in  FIG. 3  thereby further enhancing the lift capabilities. 
         [0060]    By way of example the lips in the above described embodiments may be made of a PTFE composite material. Alternatively the lips may be segmented, with two or more materials allowing a relatively dense material to be provided such as to enhance lift. 
         [0061]    Referring to  FIG. 5 , the lip  71  is similar to that of the  FIG. 3  embodiment except that the radial extension is replaced by a metal ring  73  (or a spring) which again acts to increase the mass of the end of the lip, thereby promoting lift when the equipment is rotating. 
         [0062]    Referring to  FIG. 6 , the lip  81  is similar to that of the  FIG. 3  embodiment except that the radial extension  83  is provided with an enlarged end  85 , providing a longitudinal flange. 
         [0063]    Referring to  FIG. 7 , the lip  91  is similar to that of  FIG. 6  except that a metal ring or spring  93  is secured to the enlarged end  95 .