Abstract:
The present invention relates to a compressible bladder for easing the process of opening a pressure-sealed chamber. The valve comprises a valve body having an interior, wherein media is adapted to flow therethrough; a bonnet defining a chamber carried by the valve body; a plug having a first position and a second position, wherein the plug prohibits media to flow through the valve body in the first position, and the plug does not prohibit media to flow through the valve body in the second position; an elongated stem adapted to move the plug between the two positions, wherein the stem is positioned between the valve body and the bonnet; and a compressible bladder positioned in the chamber of the bonnet adapted to compress upon an increase of pressure within the chamber of the bonnet.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority of U.S. Provisional Patent Application No. 60/718,933, filed 20 Sep. 2005, the entire contents of which is hereby incorporated by reference. 
     
    
     BACKGROUND  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to bladders and, in particular, to relieving pressure in a chamber by providing a compressible bladder in the chamber.  
         [0004]     2. Description of Related Art  
         [0005]     Valves are devices adapted to start, stop, or regulate flow of media, i.e., fluid or gas, in a pipeline. Commonly, gate valves are implemented to regulate media flow.  
         [0006]      FIGS. 1-2  illustrate conventional valves. A conventional valve  100  includes a handwheel  105 , a stem  110 , a packing  115 , a bonnet  120  defining a chamber  140 , a disc or plug  125 , and a valve body  130 . The valve  100  can be a gate valve, and is the device which can start, stop, or regulate media flow, typically in a pipeline.  
         [0007]     The handwheel  105  (often referred to a “wheel” or “handle”) can be rotatable. As the handwheel  105  is rotated, it enables the stem  110  to move the disc  125  downwardly toward the valve body  130 . Alternatively, rotating the handwheel  105  in the opposite direction enables the stem  110  to move the disc  125  upwardly away from the valve body  130 .  
         [0008]     The packing  115  is adapted to secure media housed in the valve body  130  and the chamber  140 . The packing  115  is often a malleable compound that enables a seal of the valve  100  to be tightened, and typically surrounds the stem  110 . The characteristics of the packing  115  preferably include it to be both strong and hard enough to hold the pressure of fluid or gas in the valve  100 , yet soft enough to be compressed into shape. The compression on the packing  115  prohibits valve  100  leakage.  
         [0009]     The chamber  140  is formed by bonnet  120  and can house the disc  125  when the disc  125  does not plug the valve body  130 .  
         [0010]     The handwheel  105  is connected to the stem  110 , which is connected to the disc  125 . As the handwheel  105  is rotated the disc  125  is either inserted or removed from the valve body  130 , depending on the rotation of the handwheel  105 .  
         [0011]     When the disc  125  is absent from the valve body  130 , or not plugging, the disc  125  is housed in the chamber  140  of the bonnet  120 . As the disc  125  is inserted into the valve body  130 , media enters the chamber  140 . Eventually, the handwheel  105  is rotated enough to place the disc  125  in the valve body  130 . Once the disc  125  is fully inserted into the valve body  130 , the chamber  140  is sealed. Typically, the media that entered the chamber  140  fills the chamber  140  completely.  
         [0012]     As the temperature in the chamber  140  changes, the pressure within the chamber  140  also changes. As the chamber temperature rises, the pressure rises. The pressure in the chamber  140  can be so great that it is nearly impossible for an operator to move the handwheel  105 , in an effort to remove the disc  125  from the valve body  130 . The chamber  140  needs to be regulated to permit adjustment of the disc  125 .  
         [0013]     There are two conventional methods of releasing the pressure in the chamber. A first requires drilling a hole in the chamber to bleed off part of the pressurized fluid or gas housed in the chamber. This is dangerous, depending on the media in the valve body, and compromises the chamber, as it is not pressure-sealed. A second conventional method requires a relief valve that will allow control of the bleeding of the media from the chamber. This method decreases the seal of the disc within the valve body.  
         [0014]     A method of a fluid regulating valve is described in U.S. Pat. No. 2,051,484 to Jordan (the &#39;484 patent). The &#39;484 patent describes a pressure regulating valve. The pressure regulating valve is a method of varying pressure in a system by using a spring. In this description, fluid also moves outside the valve, which can be dangerous.  
         [0015]     Another method of a fluid regulating valve is described in U.S. Pat. No. 2,511,342 also to Jordan (the &#39;342 patent). This method is an improvement over the &#39;484 patent. The device modulates pressure through media flow. The method requires fluid to flow from one chamber to another, enabling pressure control.  
         [0016]     What is needed, therefore, is a device enabling pressure control of a chamber of a valve. Preferably, the device enabling pressure control of the chamber will not require a hole in the chamber for media to bleed therefrom.  
       SUMMARY  
       [0017]     The present invention relates to a compressible bladder adapted to compress based on an increase in pressure in a sealed chamber. In one embodiment, the compressible bladder minimizes pressure in a closed valve, the valve including a valve body, a bonnet defining a chamber, and a stem adaptable to travel within the bonnet. The compressible bladder includes a shell and a connection assembly. The shell defines a hollow interior, and is adapted to compress based on a predetermined amount of pressure within the chamber. The interior of the shell is preferably filled with compressible media. The connection assembly secures the shell within the chamber of the bonnet in a position as to not interfere with movement of the stem.  
         [0018]     In another embodiment of the present invention, the compressible bladder is preferably positioned in a valve. A valve includes a valve body, a bonnet, a plug, an elongated stem, and the compressible bladder. The valve body of the valve includes an interior, wherein media is adapted to flow therethrough. The bonnet defines a chamber carried by the valve body. The plug of the valve has a first position and a second position, wherein the plug prohibits media to flow through the valve body in the first position, and the plug does not prohibit media to flow through the valve body in the second position. Further, the elongated stem of the valve is adapted to move the plug between the two positions, wherein the stem is positioned between the valve body and the bonnet. The compressible bladder is positioned in the chamber of the bonnet, and is adapted to compress upon an increase of pressure within the chamber of the bonnet.  
         [0019]     In yet another embodiment of the present invention, a method of relieving pressure in a chamber is described. The method of minimizing pressure in a chamber comprises providing a compressible bladder adapted to compress upon an increase in pressure; pressurizing a sealed chamber; and compressing the compressible bladder in the pressurized sealed chamber based on an increase in pressure.  
         [0020]     Further features of the invention, and the advantages offered thereby, are explained in greater detail hereinafter with reference to specific embodiments illustrated in the accompanying drawings, wherein like elements are indicated by like reference designators. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  illustrates a cross-sectional view of a conventional valve.  
         [0022]      FIG. 2  illustrates a perspective, partial cross-sectional view of a conventional valve.  
         [0023]      FIG. 3  illustrates a cross-sectional view of the conventional valve having the compressible bladder, in accordance with an exemplary embodiment of the present invention.  
         [0024]      FIG. 4  illustrates a perspective view of the compressible bladder, in accordance with an exemplary embodiment of the present invention.  
         [0025]      FIG. 5  illustrates a cross-sectional view along A-A of  FIG. 4  depicting the compressible bladder in an uncompressed state, in accordance with an exemplary embodiment of the present invention.  
         [0026]      FIG. 6  illustrates a cross-sectional view along A-A of  FIG. 4  depicting the compressible bladder in a compressed state, in accordance with an exemplary embodiment of the present invention.  
         [0027]      FIG. 7  illustrates a cross-sectional view of a compressible bladder in an uncompressed state secured to a chamber, in accordance with another exemplary embodiment of the present invention.  
         [0028]      FIG. 8  illustrates a cross-sectional view of the compressible bladder in a compressed state secured to the chamber, in accordance with an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0029]     To facilitate an understanding of the principles and features of the invention, it is explained hereinafter with reference to its implementation in an illustrative embodiment. In particular, the invention is described in the context of being a compressible bladder in a valve for easing the task of opening a valve after an increase in pressure makes it difficult to open the valve.  
         [0030]     The invention, however, is not limited to its use as a compressible bladder in a valve. Rather, the invention can be used when a device for easing the task of opening/closing an apparatus after an increase in pressure occurs as is desired, or necessary. Thus, the device described hereinafter as a compressible bladder in a valve can also find utility as a device for other applications, beyond that of a valve.  
         [0031]     Additionally, the material described hereinafter as making up the various elements of the invention are intended to be illustrative and not restrictive. Many suitable materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of the invention. Such other materials not described herein can include, but are not limited to, for example, materials that are developed after the time of the development of the invention.  
         [0032]     Referring now to figures, wherein like references numerals represent like parts throughout the view, the present compressible bladder in a valve will be described in detail.  
         [0033]      FIG. 3  illustrates a cross-sectional view of the valve having a compressible bladder positioned therein, in accordance with an exemplary embodiment of the present invention. This figure illustrates the valve body  130  plugged by the disc  125 . The direction of media flow is indicated by the arrow. When the valve body  130  is plugged, the bonnet  120  forms the sealed chamber  140 . Consequently, different pressure levels are generated throughout the valve  100 .  
         [0034]     For instance, when the disc  125  is in an open position, the pressure in the chamber  140  is similar to the pressure in the valve body  130 , i.e., P 1 =P 2 =P 3 . When the stem  110  is stroked such that the disc  125  is placed into the valve body  130  (i.e., inhibiting flow of media in the valve body  130 ), the area P 2  becomes bottled-up or sealed. Accordingly, the media in chamber  140 , or area P 2 , can be pressure-sealed when the plug  125  stops media flow in the valve body  130 .  
         [0035]     When the chamber  140  becomes sealed, media is captured therein. As a result, a change in pressure or temperature can cause the media sealed in the chamber  140  to expand or contract. For example, if the temperature rises, or area P 2  heats up, the pressure in area P 2  will increase causing the media to expand. This pressure increase is due to the media not having an ability to escape. Consequently, when an operator attempts to raise the disc  125  via the stem  110 , and thus open the valve body  105 , the pressure can be so great that raising the disc  125  can be overwhelmingly difficult.  
         [0036]     There are two standard approaches to release pressure in the chamber  140 . The first requires drilling a hole in the reverse flow seat to bleed off part of the media housed in the chamber  140 . This approach degrades the sealing capability of the valve  100 , and makes the chamber  140  inferior, and not completely pressure sealed. The chamber  140  is seated to flow in one direction. Further, this first approach decreases the seal of the disc  125  within the valve body  105 , and can create dangerous situations with bleeding the media from the chamber  140 , for the media can be a toxic chemical. A second approach to release pressure in the chamber requires adding a pressure boundary to the chamber  140  and attaching a relief valve that can allow bleeding off of the media from a hole in the chamber  140  that the relief valve covers. This approach increases danger, as a connection can ultimately leak or fail. This possible leakage could be extremely dangerous if the media housed in the chamber  140  is hazardous to humans.  
         [0037]      FIG. 3  illustrates the compressible bladder  200  positioned in the chamber  140 . As the pressure in the chamber  140  rises, the stem  110  can be difficult to stroke. The compressible bladder  200  can compress to reduce the pressure in the chamber, wherein easing the task of stroking the stem  110 , or moving the plug  125 . The compressible bladder  200  can be placed in a position as to not interfere with the stem  110  of the valve  100 .  
         [0038]      FIG. 4  illustrates a new way to relieve such pressure, which is superior to conventional methods.  FIG. 5  illustrates a cross-sectional view along A-A of the bladder of  FIG. 4  depicting the compressible bladder in an uncompressed state, in accordance with an exemplary embodiment of the present invention.  FIG. 6  illustrates a cross-sectional view along A-A of  FIG. 4  depicting the compressible bladder in a compressed state, in accordance with an exemplary embodiment of the present invention.  
         [0039]     Referring to  FIGS. 4-6 , the compressible bladder  200  can include a shell  205  and a non-interfering assembly, which can be a connection assembly  215 . The shell  205  defines a hollow interior  210  that is adapted to compress based on a predetermined amount of pressure within the chamber  140 . Preferably, the interior  210  of the shell  205  is filled with compressible media, which can be different from the media flowing through the valve. The connection assembly  215  is adapted to secure the shell  205  within the chamber  140  of the bonnet  120  in a position as to not interfere with movement of the stem  110 .  
         [0040]     The shell  205  can comprise different materials. In an exemplary embodiment, the shell  205  can be made of stainless steel. Stainless steel is selected in this exemplary embodiment because it has strong characteristics, and can be designed to have a thin layer. The material used for the shell  205  of the compressible bladder  200  should provide some movement or flexibility, but not move plastically. Preferably, the material of the shell  205  can be able to compress. Typically, the shell  205  of the compressible bladder  200  can be composed of metal, plastic, a composite thereof, and the like.  
         [0041]     The size of the compressible bladder  200  can range in size from a few square centimeters to numerous square meters, depending on the size of the pressure-locked chamber that is to be balanced. The application and area determine the size of the compressible bladder  200 . Likewise, the volume of the compressible bladder  200  is dependent on the size needed.  
         [0042]     The compressible bladder  200  can be many shapes. For example, the compressible bladder  200  can have a spherical, oval, convex, or bi-convex shape.  
         [0043]     The compressible bladder  200  can also be considered a collapsible bladder, a gate valve pressure lock, or a clamshell. The compressible bladder  200  can perform as if a permanent air bubble were included in the sealed chamber  140 . Accordingly, if the air bubble were to be included in the chamber  140 , the pressure could be reduced as the air bubble could compress to permit enough media to slip out of the chamber  140 . Thus, the compressible bladder  200  enables the opening of the valve  100 , via the stem  110 , even if the chamber  140  is full and an elevated temperature or pressure is attained. Typically, due to the increase in pressure, the stem  110  could not move and thus the disc  125  could not be removed from the valve body  105 . The compressible bladder  200  can ease the task of opening the valve body  105 , by being able to compress.  
         [0044]     The interior  210  of the compressible bladder  200  can be filled with a low density gas. For instance, the interior  210  can include helium, hydrogen, argon, nitrogen, oxygen, and the like.  
         [0045]     The gas in the interior  210  is compressed in the compressible bladder  200  when media in the chamber  140  pressurizes, but the gas in the interior  210  of the compressible bladder  200  is not released, just compressed; the mass of gas in the interior  210  does not change, i.e., no gas is released or captured in the compression. The gas is compressed by the increasing external pressure from increasing temperature/pressure in the chamber  140 . The volume of the compressible bladder is decreased by the external pressure caused by increased pressure/temperature, and thus limits the external pressure around it in the closed volume. The chamber  140  is a closed volume, because it is sealed. When the limited external pressure is relieved, but the disc  125  unplugging the valve body  105 , the gas expands, and the compressible bladder  200  returns to it original volume, and uncompressed state. Consequently, the compressible bladder  200  is ready to perform this compression and expansion many times, as is necessary. The shell  205  of the compressible bladder  200  is not strained plastically, and thus will return to its original shape when the pressure source is removed.  
         [0046]      FIG. 5-6  illustrates volume change between the compressed state ( FIG. 6 ) and the uncompressed state ( FIG. 5 ) indicating that the pressure will not rise significantly in the chamber  140 .  
         [0047]     The compressible bladder  200  can be secured to an interior of the chamber  140  with the connection assembly  215 . The connection assembly  215  can include a means of welding, bonding, bolting, and the like the compressible bladder  200  to the interior of the chamber  140 . In a preferred embodiment, the compressible bladder  200  is positioned in a location as to not interfere with the insertion and removal of the disc  125  via the stem  110 ; that is, the compressible bladder  200  is positioned as to not interfere with the stem  115 . The connection assembly  215  can include a bolt and an extending member defining a hole to receive the bolt, wherein the bolt is driver through the hole of the extending member into the interior of the chamber  140 .  
         [0048]     In an exemplary embodiment, the compressible bladder  200  can be placed into the chamber  140 . For instance, the compressible bladder  200  can be placed in area P 2 . As a result of the rise in pressure the compressible bladder  200  changes from an uncompressed state (see  FIG. 5 ) to a compressed state (see  FIG. 6 ). The compressible bladder  200  can compress because of the material that it is made up of (e.g., thin stainless steel), and because it is filled with an easily compressible gas.  
         [0049]     The rising pressure in P 2  consequently compresses the compressible bladder  200 . The rise in pressure in area P 2  is limited. The compressible bladder  200  does not permit the pressure in the given area housing (i.e., the chamber  140  or area P 2 ) to build to any appreciable value. Thus, in an exemplary embodiment, the compressible bladder  200  enables the valve to open through a range of chamber  140  pressures and not pressure lock.  
         [0050]      FIG. 7  illustrates the compressible bladder in an uncompressed state having a convex shape secured to a chamber, in accordance with an exemplary embodiment of the present invention. In an exemplary embodiment, the compressible bladder  200  can have a convex shape, such that the interior  210  is formed from the shell  205  and the interior of the chamber  140 . The compressible bladder  200  can compress based on pressure in the chamber  140 .  FIG. 8  illustrates the compressible bladder in a compressed state secured to a chamber, in accordance with an exemplary embodiment of the present invention.  
         [0051]     In another exemplary embodiment, a number of compressible bladders  200  can be in provided in the chamber  140 . In total, a plurality of compressible bladders  200  can compress to cumulatively reduce the pressure in the chamber  140 .  
         [0052]     From the foregoing, it can be seen that the invention provides a number of different compressible bladders, which can be in a valve. The various embodiments of the invention described above provide improved and easy opening in a pressure sealed chamber, when compared with conventional approaches. Additionally, according to various embodiments of the invention, the compressible bladder can be provided with a shell having an interior that is securable to an interior of the sealable chamber. Unlike prior approaches, the compressible bladder locks the pressure in the valve, and eases opening a pressure-sealed chamber.  
         [0053]     It will be appreciated by those skilled in the art, however, that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, while the invention has been described in the context of compressible bladder in a valve setting, the concepts described herein need not be limited to these illustrative embodiments. For example, compressible bladders can be used in other embodiments to control the amount of pressure in the pressure-sealed chamber, and would enjoy the same benefits as the compressible bladder in valves, as described above.  
         [0054]     Additionally, the specific configurations, choice of materials, and the size and shape of various elements, can be varied according to particular design specifications or constraints requiring a bladder as constructed according to the principles of the invention. Such changes are intended to be embraced within the scope of the invention.  
         [0055]     The presently disclosed embodiments are, therefore, considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.