Abstract:
A swellable element includes a mandrel, a swellable material disposed about the mandrel and at least one cut in the swellable material and method.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to U.S. Provisional Patent Application Ser. No. 60/939,885, filed May 24, 2007, the entire contents of which are specifically incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Swellable materials have been used to assist in setting seals or as seals themselves for a significant period of time in various industries. Such materials are capable of generating a high contact force against a nearby a structure which is capable of either of the noted uses of setting or sealing, or in some cases both, when exposed to a swelling fluid reactive with the swelling material. 
         [0003]    Swelling can occur through absorption or chemical reaction. In applications where a higher degree of swelling, for either purpose is needed, difficulty has been experienced as sufficient volumetric change has not been reliably achievable and in addition when higher volumetric change is attempted, the material itself loses physical integrity thus compromising the ultimate goal of the application. 
       SUMMARY 
       [0004]    A swellable element includes a mandrel, a swellable material disposed about the mandrel and at least one cut in the swellable material. 
         [0005]    A swellable element includes a mandrel and a plurality of annular discs of a swellable material disposed about the mandrel. 
         [0006]    A method for making a swellable element includes disposing a swellable material on a mandrel and cutting the swellable material. 
         [0007]    A method for making a swellable element includes disposing a plurality of discs of a swellable material on a mandrel closely adjacent one another and affixing at least one of the plurality of discs of swellable material to the mandrel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
           [0009]      FIG. 1  is a schematic perspective cross sectional representation of a prior art swellable seal; 
           [0010]      FIG. 2  is a schematic cross sectional view of one embodiment of an improved swelling seal as described herein; 
           [0011]      FIG. 3  is a schematic end view of another embodiment of an improved swelling seal as described herein; 
           [0012]      FIG. 4  is a schematic perspective view of another embodiment of an improved swelling seal as described herein; 
           [0013]      FIG. 5  is a schematic cross sectional view of another embodiment of an improved swelling seal as described herein; 
           [0014]      FIG. 6  is a schematic cross sectional view of another embodiment of an improved swelling seal as described herein; and 
           [0015]      FIG. 7  is a schematic cross sectional exploded view of another embodiment of an improved swelling element as described herein utilizing a plurality of swellable discs. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring to  FIG. 1  (prior art), one of the problems associated with higher volumetric expansions of swellable materials is that the material itself when configured for use as an element such as an annular seal  10  for example (hereinafter referred to as “seal” for simplicity), is bonded or otherwise mounted to a mandrel  12 , generally in a way that reduces access of swelling fluid to the swellable material. In other words, the surfaces of an exemplary annular seal that are contactable by swelling fluid are an outside dimension surface  14  of the seal and end surfaces  16  and  18  at the axial ends of the seal. An inside dimension surface  20  of the seal is relatively protected from contact with swelling fluid applied to the annular seal  10 . This is due to whatever means has been used to mount the annular seal to the mandrel. Resultantly, the exposed surfaces of the swellable material  14 ,  16 ,  18  must expand more significantly to achieve contact with an opposing structure (not shown) than they would have to have done if a greater proportion of the swellable material were “wettable” by the swelling fluid. More specifically, swelling would occur to a greater extent and more evenly if a greater percentage of the original volume of the material could be affected by the swelling fluid. Greater distribution of the swelling fluid throughout the volume of the swellable material increases the potential contact pressure generatable by the swellable material, and reduces sponginess of the swelled swellable material. Such sponginess can often be experienced when a greater expansion of some parts of the swellable material than others makes up for the lack of swelling in those other parts of the swellable material. A swellable material as contemplated herein may be an elastomeric material such as rubber, copolymers, plastics, thermoplastics, etc. 
         [0017]    In accordance with an embodiment of the invention and referring to  FIG. 2 , the wettable surface area of the swellable material is increased by creating at least one cut  140  in the material of element  110 . The at least one cut may be in any direction including orthogonally annular as shown and may be of any depth within the material with commensurate benefit with respect to increased wettability of the swellable material. The at least one cut creates additional surface area of the element exposed to surrounding environment including the swelling fluid applicable to the specific type of swellable material being used. The greater the depth and length of the cut the greater surface area of the swellable material; the greater the surface area contactable by the swelling fluid, the greater the increase in wettability. In short, any configuration of the element that increases the surface area thereof while at the same time avoiding a reduction in the volume of the element will result in improved performance. Configurations include, in addition to those noted above, axially spirally cutting the element along cut line  142  such that the element  110  is wrapped around the mandrel  112  similar to the configuration of a roll of tape ( FIG. 3 ), axially helically cutting the element along cut line  144  ( FIG. 4 ), axially parallel cut(s) along lines  146  ( FIG. 5 ), zig-zag cuts along line  148  ( FIG. 6 ), etc. Furthermore, short cuts may be made in the element in the same direction or in different directions a plurality of which may together make up a geometrical form such as any of the foregoing forms or otherwise, if desired. 
         [0018]    In an alternate embodiment, and referring to  FIG. 7 , the swellable material is configured as a plurality of annular discs  260  that are then stacked axially adjacent one another on a mandrel  212  such that a swelling fluid is provided relatively easy access to a greater surface area of the swellable material. While the individual annular discs are in one embodiment each affixed, for example, glued, bonded, or similar at their respective inside dimensions  220  to the mandrel  212  thereby inhibiting swelling fluid access to that inside dimension, in another embodiment only the end positioned annular discs  262  are bonded or otherwise affixed to the mandrel while others of the discs remain unfixed. In this embodiment, the annular discs that are not themselves bonded or otherwise affixed to the mandrel are receptive to swelling fluid at their respective inside dimensions. This, of course, will further enhance the swellability of the element. 
         [0019]    While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.