Abstract:
An isolator device, which may be a bearing seal or a bearing isolator, for use hindering fluid flow between components which are rotating relative to each other about a longitudinal axis, the flow being in one direction parallel to this axis, includes a stator for securing to a rotary fixed one of the components and a rotor for securing to a relatively rotating one of the components. The stator has a surface which extends longitudinally and adjacent to a surface of a component, which rotates relative to the stator. The fluid flow is between the two surfaces and the stator surface is non-parallel to the adjacent component surface and is shaped to promote fluid flow in a direction opposing the general fluid flow direction.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to bearing protectors and their use in rotating equipment, especially devices, which prevent the ingress or egress of a fluid or solid to a cavity, resulting in deterioration of equipment life. Such devices are also often referred to as bearing seals or bearing isolators. The use of such rotary seals extends beyond the protection of a bearing in rotating equipment. Accordingly, while reference will be made below to bearing protectors, it should be understood that this term is used, as far as the invention is concerned, in connection with such wider uses. More broadly, the term isolator device may be used.  
       BACKGROUND OF THE INVENTION  
       [0002]     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.  
         [0003]     Bearing protectors generally fall into two categories: repeller or labyrinth bearing protectors; and mechanical seal bearing protectors. Reference is made to co-pending PCT patent publication No. WO0605950A concerned with labyrinth seal bearing protection and which discloses a substantially non-contacting bearing protector with a static shut off device.  
         [0004]     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.  
         [0005]     In conventional labyrinth devices, the close radial counter rotational members are substantially parallel to each other and run parallel to the centreline of the shaft. Unfortunately, these substantially parallel surfaces have limited effectiveness at discouraging the longitudinal movement of fluid.  
       STATEMENTS OF THE INVENTION  
       [0006]     According to the present invention there is a provided an isolator device for use in hindering fluid flow between components which are rotating relatively to each other about a longitudinal axis, said flow being in one direction parallel to said axis, the device comprising a stator for securing to a relatively fixed one of said components and a rotor for securing to a relatively rotating one of said components, the stator having a surface which extends longitudinally and adjacent to a surface of a component which rotates relative to said stator, the fluid flow being between said surfaces, the stator surface being non-parallel to the adjacent rotating component surface and being shaped to promote fluid flow in a direction opposing said one direction.  
         [0007]     Preferably, the surface of the stator forms a least part of a recess within said stator. More preferably, the recess is non-rectangular in longitudinal section.  
         [0008]     Typically, the recess will be located adjacent to a shaft of a pump or other rotating equipment. The shaft may be supported by bearings within a bearing housing.  
         [0009]     The recess may have a gradually increasing depth in the direction of flow of the fluid (said one direction) and the resultant wedge-shaped longitudinal section of the recess results in fluid movement within the recess which tends to hinder the longitudinal flow in said one direction. Although not limited to any particular fluid movement within the recess, the creation of one or more fluid flow vortices can be envisaged.  
         [0010]     Reference is made above to components of the isolator device when the device is in use, that is to say, with relative rotation between the components. It should be appreciated, however, that this is not intended to limit the scope of this invention to a device solely when it is in use but rather to enable the components of the device to be appropriately defined. The invention is directed to the device whether incorporated in rotatable equipment and whether that equipment is in a dynamic situation (in use) or is static. Furthermore, the invention extends to the device separate from, but capable of being installed in, a particular piece of equipment.  
         [0011]     The present invention also provides rotating or rotatable equipment incorporating an isolating device of the invention.  
         [0012]     Preferably, the gradually increasing depth of the recess is provided by a surface inclined at an angle to the longitudinal axis or from 1° to 45°. Preferably, the maximum depth of the recess is at or closely adjacent to the upstream end of said recess, that is to say, closer to that end of the device which, in use, is entered by the flowing fluid.  
         [0013]     Preferably, the recess is terminated by an end wall extending to the maximum depth of the recess at an angle to the longitudinal axis of from 90° to 45°.  
         [0014]     Preferably, a velocity reducing groove is located in said stator adjacent to said recess. More preferably, the velocity reducing groove is situated upstream of the recess.  
         [0015]     The recess may, instead of being a substantially wedge-shaped (in longitudinal section) groove, be a three-sided (in longitudinal section) groove have a substantially longitudinally extending base and substantially radially extending end walls. Preferably, each one of said end walls is inclined to the radial plane. More preferably, both of said end walls are inclined to be radial plane.  
         [0016]     Preferably, the recess includes a rib extending from said base in a radially inwards directions.  
         [0017]     Preferably, at least one of the edges of the recess is rounded. These edges may be the edges between the base and the end wall and/or those at the mouth of (the opening into) the recess.  
         [0018]     Preferably, the rib is provided by smoothly curved, radially extending surfaces.  
         [0019]     Preferably, the stator is provided with a deformable toroidal member which seals said stator to a relatively fixed one of said components.  
         [0020]     Preferably, the rotor is provided with a deformable toroidal member to seal said rotor to a relatively rotatable one of said components. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     The accompanying drawings are as follows:— 
         [0022]      FIG. 1  is a longitudinal section of a labyrinth seal bearing protector of the invention mounted on a shaft;  
         [0023]      FIG. 2  shows in detail, again in longitudinal section, a part of the stator of the bearing protector of  FIG. 1 ;  
         [0024]      FIG. 3  is a longitudinal section of another labyrinth seal bearing protector of the invention mounted on a shaft; and  
         [0025]     FIGS.  4  to  6  show various recesses forming parts of further labyrinth seal bearing protectors of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     The invention will now be described, by way of examples only, with reference to the accompanying drawings.  
         [0027]     Referring to  FIG. 1  of the accompanying drawings, an isolator device, or bearing protector,  10  is fitted to an item of rotating equipment  11 . The equipment includes a rotating shaft  12  and the stationary housing  13 . The stationary housing  13  typically carried a bearing (not shown).  
         [0028]     The area marked ‘X’ in  FIG. 1 , located at one longitudinal end of the bearing protector  10 , may contain fluid and/or solids and/or foreign debris and/or atmosphere. The material in area ‘X’ may conveniently be referred to as ‘product substance’, a term used to describe either a single or a mixed medium.  
         [0029]     Area ‘Y’ at the other longitudinal end of the bearing protector  10  can also contain a variety of fluids and solids, Typically, however, if this area is occupied by atmosphere. In general, the material occupying this area will be termed ‘atmospheric substance’ and the term is used to describe either single or mixed medium.  
         [0030]     The bearing protector  10  comprises a rotor  14  located longitudinally adjacent to a stator  15 . A deformable toroidal member, in the form of elastomeric ring  16 , provides a radial seal between housing  13  and stator  15 . Similarly, a further deformable toroidal member, in the form of elastomer ring  17 , provides a radial seal between the shaft  12  and the rotor  14 .  
         [0031]     Static shut-off device  18 , located within a roughly rectangular space defined on three sides by rotor  14  and one side by stator  15 , is substantially as described in PCT patent publication No. WO 0605950A.  
         [0032]     Referring now to  FIG. 2  of the accompanying drawings, there is depicted detail of that part of stator  15  which lies adjacent to the shaft  12 . The stator in this region includes an annular groove  19  defined by radial walls  19   a  and  19   b  and inter-connecting circumferential wall  19   c.  Groove  19  acts to reduce the velocity of fluid, which may be a single or mixed medium as mentioned above, entering the gap between stator  15  and shaft  12  from area ‘X’. In  FIG. 2  the size of the arrows indicates the velocity of flow and it will be seen that, within groove  19  and between groove  19  and shaft  12 , the velocity is substantially reduced.  
         [0033]     Located adjacent to  19 , and downstream thereof, is an annular recess  20  which is substantially wedge-shaped in longitudinal section. The depth of recess  20  decreases gradually, from its maximum depth, in the direction, from area ‘X’ and ‘Y’ which is the direction of flow of the fluid. The wedge-shaped longitudinal section of recess  20  is made up of a gently inclined (to the longitudinal axis) annular surface  21  and a much more steeply inclined surface  22  providing a shoulder to the recess.  
         [0034]     The gently inclined surface  22  may be inclined at any angle between 1 and 45° to the shaft axis. Preferably the angle of inclination to the shaft axis is for 15° to 30°, but more preferably 20°.  
         [0035]     The more steeply inclined surface  22  is preferably inclined at an angle to the shaft axis of from 90 to 45°, preferably 60 to 80°, and more preferably 75°.  
         [0036]     Accordingly, while the equipment is in operation, with shaft  12  rotating in the direction shown by the arrow partly encircling the shaft, the fluid  24  is subjected to centrifugal forces which propel it towards the surface  21  of recess  20 . Closer to the steeply inclined surface  22  the fluid may be caused to carry out a somewhat circular motion as indicated by the arrows in that region. The effect of recess  20  is to hinder fluid flow from region ‘X’ and region ‘Y’ with the result that the amount of fluid entering region ‘Y’ is substantially reduced or even eliminated. As described, with reference to the  FIGS. 1 and 2  embodiment, the inclined surface  21  of the stator is adjacent and substantially facing the rotor surface, namely, that of the shaft  12 . In this case the rotor surface extends parallel to the shaft axis. In another embodiment of the present invention, the rotor surface may also be inclined, effectively reducing the angle between the converging surfaces of the stator and the rotor.  
         [0037]     As indicated above the radial distance between the rotating surface  23  (shaft  12 ) and the inclined stator surface  20  preferably increases in a direction towards the fluid entry source. In this way, the fluid tends to be returned back to that source.  
         [0038]     By having surface  22  very steeply angled (it may be perpendicular to the longitudinal axis), the longitudinally travelling fluid is thrown radially inwardly against the shaft  12  at the position where the centrifugal forces are at their lowest magnitude. This position typically coincides with that of maximum depth of the recess  20 .  
         [0039]     Although the exact movement of the fluid within recess  20  will depend on a number of factors, it may be that in a certain situation so called standing vortices  40  are created adjacent to surface  22 . These vortices  40  can be described as swirling, spiral movements of fluid within the recess. Vortices  40  provide a longitudinal fluid area, helping to prevent longitudinal movement of fluid in a direction away from the fluid source.  
         [0040]     Referring now to  FIG. 3  of the accompanying drawings a second embodiment of a bearing protector  51 , in accordance with the present invention, includes a stator  53 , sealed to equipment housing  55  by elastomer ring  57 , and a rotor  59 , sealing to shaft  61  by elastomer ring  63 .  
         [0041]     In this case, the stator is provided with a plurality of inclined surfaces located adjacent to rotor component. A first longitudinally adjacent pair of said surfaces  65  and  67  is provided adjacent to shaft  61 . A further inclined surface  69  forms part of a recess  71 , which accommodates a castellated (in cross section) arm  73  of rotor  50 . In this case the angle of inclination of surface  69  to the longitudinal axis is very low.  
         [0042]     A further inclined surface is provided on arm  75  of stator  53  and this surfaces lies adjacent to the outer (again castellated) surface of rotor  59 .  
         [0043]     All these arrangements of inclined surfaces act to inhibit flow (in one direction or the other) from one side of bearing protector  51  to the other side.  
         [0044]     Referring to FIGS.  4  to  6  of the accompanying drawings, there is illustrated embodiments of the present invention in which the fluid flow inhibiting component is provided by a recess  81  which may be seen as a modification of recess  19  of the  FIG. 2  embodiment whether alone or together with other flow inhibiting entities such as recess  20  in the  FIG. 2  embodiment.  
         [0045]     The recesses depicted in FIGS.  4  to  6  are substantially three-sided having a base  83  and end walls  85  and  87 . In the  FIGS. 4 and 5  embodiments, the end walls  85  and  87  are oppositely inclined to the radial plane such that the mouth of the recess is of shorter longitudinal length than that the base  83 .  
         [0046]     In the cases of the  FIGS. 5 and 6  embodiments, the recess  81  is provided with an integral, radially extending rib which is located substantially centrally within base  83 .  
         [0047]     As illustrated, particularly in  FIGS. 4 and 5 , the various edges of the recess, those between the base  83  and the end walls  85  and  87  and those at the mouth of the recess, are rounded.  
         [0048]     The radially extending walls of rib  89  are, as illustrated in  FIGS. 5 and 6 , gently curved in a direction radially outwardly form the ends of the rib.  
         [0049]     The shapes of the recesses in FIGS.  4  to  6  are such as to promote fluid movement within the recess which tends to oppose the longitudinal fluid flow, indicated by arrows  91  and  93  within the device. The fluid flow within the recesses may be as indicated by the arrows  95  which indicate the creation of vortices. However, it should be understood that the actual fluid movement within the recesses may be of a different nature, but nonetheless hindering the main longitudinal flow.  
         [0050]     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.  
         [0051]     Furthermore, the invention may be embodied in both rotary and stationary arrangements of cartridge and component seals with metallic components as well as non-metallic components.