Imported: 10 Mar '17 | Published: 27 Nov '08
USPTO - Utility Patents
A swellable element includes a mandrel, a swellable material disposed about the mandrel and at least one cut in the swellable material and method.
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.
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.
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.
A swellable element includes a mandrel, a swellable material disposed about the mandrel and at least one cut in the swellable material.
A swellable element includes a mandrel and a plurality of annular discs of a swellable material disposed about the mandrel.
A method for making a swellable element includes disposing a swellable material on a mandrel and cutting the swellable material.
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.
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.
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.
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.
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.