Abstract:
Configurations of piston actuators having seal retainers doubly acting as pressure chambers are disclosed. Further disclosed are methods of installing pressure chambers in piston actuators.

Description:
FIELD 
       [0001]    The present invention relates to methods and devices pertaining to pressure seals on actuators. More specifically, the present invention relates to a simplified method of sealing a hydraulic actuator. 
       BACKGROUND 
       [0002]    Gate valves are generally comprised of a valve body having a central axis aligned with inlet and outlet passages, and a space between the inlet and outlet passages in which a slide, or gate, may be moved perpendicular to the central axis to open and close the valve. In the closed position, the gate surfaces typically seal against sealing rings which surround the fluid passage through the valve body. Gate valves have been used for centuries to control the flow of a great variety of fluids. Often the fluid to be controlled by the gate valve is under pressure. In the petroleum industry, gate valves are used along piping at various locations, and in particular are used in piping referred to in the petroleum industry as a Christmas tree, which is used as part of a drilling operation. 
         [0003]    Actuators to open and close the gate valves may include manual operators, diaphragm-type operators, hydraulic operators or pneumatic operators. The actuator may include a bonnet assembly, which interconnects the valve body and the valve gate, and a bonnet stem which is movable with the gate via an operator. The operator typically has a maximum force capability for applying to the bonnet stem. It is sometimes desirable to provide additional opening/closing power on a temporary basis without having to remove the original operator. It is also desirable that the same operator be adaptable to various control accessories, such as a mechanical override, hydraulic override, heat sensitive lock open device, block open cap, electrical limit switch and/or other electrical accessories. 
         [0004]    One problem associated with hydraulic or pneumatic actuators is how to maintain a pressurized state for actuation of a gate valve between an opened and closed position. Existing designs use a complex arrangement of multiple components such as retainers, seals and fasteners that result in longer times for assembly and repair of such actuators. 
         [0005]    It would therefore be desirable to eliminate the use of multiple components an instead use a single component for sealing pressure. Such a device would result in easier field maintenance and downtime. 
       SUMMARY 
       [0006]    Particular embodiments of the invention disclosed herein pertain to an actuator for moving a valve gate between open and closed positions within a valve body. In such embodiments, the actuator may comprise an actuator housing defining an axis and having a proximal end oriented toward a gate valve and a distal end oriented away from the gate valve and attached to a top plug itself having a proximal side, the actuator housing further having an inner wall; an operator shaft with a distal end and a proximal end, the proximal end extending through a bore of a packing retainer fitted within an internal bore of a bonnet and into the valve body, the bonnet operatively connected to the proximal end of the actuator housing, the operator shaft defining a shaft axis; a seal retainer with external edges and an outer wall extending in a proximal direction to a proximal external edge, the seal retainer further having a distal end, and the seal retainer being adapted to receive a piston; a piston with a wall along the actuator housing axis, the piston having a proximal side and a distal side; a downstop having a proximal side and a distal side, the distal side in contact with the piston, and the proximal side in contact with a distal end of an operator shaft, the operator shaft having a proximal end attached to the valve gate; and wherein the seal retainer is pressurizeable and upon pressurization moves the piston in a proximal direction, thereby moving the operator shaft in a proximal direction and moving the valve gate in a proximal direction. 
         [0007]    Further embodiments related to the actuator pertain to the inclusion of an actuator spring, the spring being capable of producing a biasing force opposing axial movement of the operator shaft toward the valve body. 
         [0008]    It is contemplated that in the embodiments of the invention disclosed herein may pertain to a hydraulic actuator or a pneumatic actuator. 
         [0009]    In further embodiments, at least one seal abuts at least one external edge of the seal retainer. In such embodiments, at least one seal may seal a space between the inner wall of the actuator housing and the outer wall of the seal retainer. Alternatively or additively, at least one seal may seal a space between the proximal end of the seal retainer wall and the piston wall. 
         [0010]    Certain embodiments further comprise an actuator with a top shaft. In such embodiments a top shaft may be attached to the distal side of the piston and the seal retainer may have a retainer bore having a proximal end and a distal end, wherein the top plug also has a top plug bore adapted to receive the top shaft. In such embodiments, at least one seal may surround and abut the top shaft and seal a space between the top shaft and the distal end of the retainer bore. 
         [0011]    In certain embodiments, the distal end of the seal retainer has a plurality of seals surrounding the top shaft. In such embodiments, the seals may be retained by substantially circular grooves surrounding the top shaft and either in the proximal side of the top plug or the distal side of the seal retainer. 
         [0012]    It is further contemplated that the seal retainer may function as a pressure chamber and the seals may prevent loss of pressure. In such embodiments, the actuator housing further may further comprise a pressure inlet and the seal retainer further comprises a seal retainer bore aligned with the pressure inlet. 
         [0013]    Other embodiments of the invention pertain to a method of installing a pressure chamber in a piston actuator, the method comprising: obtaining a cylindrical actuator housing defining a vertical axis and having a proximal end attached to a bonnet and a distal end, the actuator housing further having an inner wall of a defined diameter with a circular protrusion about midway between the proximal and distal ends, the protrusion extending from the inner wall in a perpendicular direction from the axis, wherein the inner diameter of the actuator housing at the protrusion has a defined protrusion diameter; installing a piston with a proximal side and a distal side and an outer wall less than or equal to the defined protrusion diameter, wherein the protrusion has a distal side, and the distal end of the piston is always distal or equal to the distal side of the protrusion; inserting a first substantially circular seal having a proximal side and a distal side into the distal end of the actuator housing, wherein the proximal side of the seal is positioned on the distal side of the protrusion, placing a seal retainer a distal side and having a cylindrical wall having a space adapted to receive the piston into the distal end of the actuator housing, the cylindrical wall having a proximal end abutting the distal side of the first substantially circular seal; placing a second substantially circular seal having a proximal side and a distal side into the distal end of the actuator housing, and attaching a top plug having a proximal side to the distal end of the actuator housing, wherein the second substantially circular seal is retained between proximal side of the top plug and the distal side of the seal retainer; and wherein the actuator housing has a pressure inlet and the seal retainer has a seal retainer bore such that the pressure inlet and the seal retainer bore are aligned and connected to a pressure source, and the seal retainer space adapted to receive the piston functions as a pressure chamber. 
         [0014]    In such embodiments of this method, the seals may prevent fluid from escaping the pressure chamber and into the actuator. 
         [0015]    In further embodiments of the method, the distal side of the piston may be attached to a top shaft, the seal retainer may have a bore adapted to receive the top shaft and the top plug may have a bore adapted to receive the top shaft. In such embodiments, the method may further comprising a installing a third substantially circular seal, the seal surrounding and abutting the top shaft and sealing a space between the top shaft and the retainer bore adapted to receive the top shaft, the seal being located between the proximal side of the top plug and the distal side of the seal retainer. 
         [0016]    It is further contemplated that in the embodiments of the invention disclosed herein, the actuator may be a hydraulic actuator or a pneumatic actuator with a piston. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a cross sectional drawing of a hydraulic actuator illustrating the sealing system. 
           [0018]      FIG. 2  is a cross sectional drawing of the hydraulic actuator illustrating the sealing system wherein the actuator is pressurized. 
       
    
    
     LIST OF REFERENCE NUMERALS 
       [0019]      10  hydraulic actuator 
         [0020]      20  top plug 
         [0021]      30  actuator housing 
         [0022]      40  threaded attachment 
         [0023]      50  top plug seal 
         [0024]      60  retainer ring 
         [0025]      70  inner polypak groove 
         [0026]      80  outer polypak groove 
         [0027]      90  inner polypak seal 
         [0028]      100  outer polypak seal 
         [0029]      110  seal retainer 
         [0030]      120  pressure chamber 
         [0031]      130  seal retainer wall 
         [0032]      140  proximal polypak seal 
         [0033]      150  actuator housing protrusion 
         [0034]      160  ware bearing indentation 
         [0035]      170  ware bearing 
         [0036]      180  combination top shaft and piston 
         [0037]      185  seal retainer distal bore 
         [0038]      190  pressure inlet 
         [0039]      200  pressure outlet 
         [0040]      210  seal retainer bores 
         [0041]      220  downstop 
         [0042]      230  operator shaft 
         [0043]      240  actuator spring 
         [0044]      250  downstop bore 
         [0045]      260  bonnet ring 
         [0046]      270  packing retainer 
         [0047]      280  bonnet bore 
         [0048]      290  bonnet 
         [0049]      300  packing retainer bonnet bore threaded interface 
         [0050]      310  packing retainer bore 
         [0051]      320  valve body 
         [0052]      380  bonnet ring threaded junction 
         [0053]      390  bolts 
         [0054]      400  valve gate 
         [0055]      410  valve throughbore 
       DETAILED DESCRIPTION 
       [0056]    The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
         [0057]    The following definitions and explanations are meant and intended to be controlling in any future construction unless clearly and unambiguously modified in the following examples or when application of the meaning renders any construction meaningless or essentially meaningless. In cases where the construction of the term would render it meaningless or essentially meaningless, the definition should be taken from Webster&#39;s Dictionary 3 rd  Edition. 
         [0058]    As used herein, the term “conduit” means and refers to a fluid flow path. 
         [0059]    As used herein, the term “line” means and refers to a fluid flow path. 
         [0060]    As used herein, the term “fluid” refers to a non-solid material such as a gas, a liquid or a colloidal suspension capable of being transported through a pipe, line or conduit. Examples of fluids include by way of non-limiting examples the following: natural gas, propane, butane, gasoline, crude oil, mud, water, nitrogen, sulfuric acid and the like. 
         [0061]    As used herein, the term “attached,” or any conjugation thereof describes and refers to the at least partial connection of two items. 
         [0062]    As used herein, the term “polypak,” or any conjugation thereof may refer to multi-purpose seals that are molded, multi-purpose sealing devices combining an O-Ring type O-spring with a conventional lip seal. 
         [0063]    Now, referring to  FIG. 1 , is a cross sectional drawing of a hydraulic actuator  10  illustrating the sealing system. As can be seen in  FIG. 1 , the hydraulic actuator  10  has a top plug  20  attached to the actuator housing  30 . In this embodiment, the attachment is a threaded attachment  40 , which may be viewed in  FIG. 2 . In other embodiments, it is contemplated that the attachment may be different, such as the use of bolts, screws, and the like. Immediately distal to the threaded attachment  40  is top plug seal  50  as and a retainer ring  60  both of which are illustrated in  FIG. 1 . The retainer ring  60  may be threaded such that there is an attachment between the outside of the retainer ring  60  and the inside of the actuator housing  30 . 
         [0064]    As seen in  FIG. 2 , the proximal end of the top plug  20  has a substantially circular inner polypak groove  70  and a substantially circular outer polypak groove  80 . Within the inner polypak groove  70  is an inner polypak seal  90 . Likewise, within the outer polypak groove  80  is an outer polypak seal  100 . Immediately distal to the top plug  20 , the polypak grooves and the polypak seals, is a seal retainer  110 , which may be viewed in  FIG. 1  or  FIG. 2 . The distal side of the seal retainer  110  engages the two aforementioned polypak seals to inhibit pressure exit from the pressure chamber, which is immediately proximal to the proximal side of the polypak seal. In addition, the seal retainer  110  has a seal retainer wall  130 , which comprises the seal retainer  110  in its entirety. The seal retainer wall  130  typically shaped in a cylindrical fashion, extending proximally from the proximal side of the seal retainer  110 . The seal retainer wall  130  has a proximal end which contacts a third or proximal polypak seal  140  which may be viewed in  FIG. 2 . In certain embodiments, immediately proximal to the proximal polypak seal  140 , such as the embodiment of  FIG. 1 , is an actuator housing protrusion  150  on which the proximal polypak seal  140  rests. 
         [0065]    In practice, the actuator housing is made of a durable metal, such as aluminum, stainless steel, titanium and the like. Likewise, the top plug may be made of a durable metal such as aluminum, stainless steel, titanium and the like. A typical actuator housing can be between about 10 inches to about 30 inches in diameter. The shape is generally spherical. In the case of using steel in the construction of the actuator housing, the thickness is typically from about ¼ inch to about ½ inch. 
         [0066]    Further, the polypak seals can be made of materials such as delrin, nylon, thermoplastics, resins, polyurethanes, phenolics, acetals, polyacrylates, epoxides, polycarbonates, polyester, aramids and the like. 
         [0067]    Still further, pertaining to the actuator housing protrusion  150 , the actuator housing protrusion  150  may possess a ware bearing indentation  160  such that a ware bearing  170  may surround the piston proximal to the seal retainer  110  as illustrated in  FIG. 2 . 
         [0068]    Within the seal retainer  110 , and surrounded by the seal retainer wall  130  is a pressure chamber  120  which may be viewed in  FIG. 1  or  FIG. 2 , which is capable of being pressurized by a gas or a liquid to move the combination top shaft and piston  180  in a distal direction. 
         [0069]    In other embodiments, it is conceivable that the top shaft and piston may be separate elements. In such embodiments, the top shaft typically would have a top shaft flange at its most proximal end and the piston would typically have an indentation capable of receiving the top shaft flange on its distal side. Typically in such cases, a retainer ring  60  secures the top shaft flange to the piston. 
         [0070]    Regarding a top shaft or a combination top shaft and piston  180 , the seal retainer  110  possesses a seal retainer distal bore  185  adapted to receive the top shaft as illustrated in  FIG. 2 . The seal retainer  110 , having a seal retainer wall  130 , is adapted to receive the piston. When the seal retainer  110  has received the piston, the inside of the seal retainer functions as a pressure chamber  120 . 
         [0071]    In most embodiments, the diameter of the top shaft portion of the combination top shaft and piston  180 , or a top shaft alone can be varied depending on loading and stress conditions on the top shaft portion of the combination top shaft and piston  180 , or a top shaft. Typically, such a diameter of the top shaft will be between one and three inches with a top shaft length between 6 and 30 inches. As the top shaft protrudes from the top plug  20 , the position of the top shaft can serve as an indicator to whether a valve gate is in the open or closed position. In general, the top shaft and piston will be made of a durable metal such as steel. 
         [0072]    The pressure chamber  120  is in fluid communication with a pressure inlet  190  and a pressure outlet  200  situated perpendicular to the distal to proximal axis of the top shaft and piston. More specifically, the pressure inlet  190  and pressure outlet  200  are bores within the side of the actuator housing  30 . Still further, the seal retainer wall  130  has seal retainer bores  210  as illustrated in  FIG. 2 , which align with the pressure inlet  190  and the pressure outlet  200 , such that pressure in the form of a liquid or a gas may enter or exit the pressure chamber  120 . 
         [0073]    Referring again to  FIG. 1 , the proximal end of the piston abuts the distal side of a downstop  220 . The downstop  220  serves to retain the operator shaft  230  and its proximal side is the distal pressure point for the actuator spring  240 . Regarding the ability of the downstop  220  to retain the operator shaft  230 , the center of the downstop  220  has a downstop bore  250  adapted to receive a distal portion of the operator shaft  230 . This distal portion of the operator shaft  230  is affixed to the downstop bore  250 . As seen in  FIG. 1 , the downstop bore  250  is threaded and adapted to receive a reciprocally threaded distal portion of the operator shaft  230 . In alternative embodiments, the distal portion of the operator shaft  230  may be affixed to the downstop bore  250  by pinning or bolting the distal portion of the operator shaft  230  to the downstop bore  250 . While it is contemplated that the downstop  220  and the operator shaft  230  may be made of any rigid material, these components are preferably formed from stainless steel. 
         [0074]    As indicated previously the actuator spring  240  has a distal end and a proximal end. The distal end of the actuator spring  240  contacts the proximal end of the downstop  220 . Likewise, the proximal end of the actuator spring  240  is in contact with the bonnet ring  260 . Further, the actuator spring  240  has an internal area such that the actuator spring surrounds  240  the operator shaft  230  and, near the distal end of the actuator, surrounds the packing retainer  270 . 
         [0075]    The packing retainer  270  of the present invention as illustrated in  FIG. 1 , is situated within the actuator housing  30  near its proximal end. Further the packing retainer  270 , which in many embodiments has a cylindrical shape, fits within the centrally positioned bonnet bore  280  of the bonnet  290 . The bonnet bore  280  is along a distal to proximal axis defined by the operator shaft  230 . The packing retainer, in most embodiments, is affixed to the bonnet bore  280  through a packing retainer bonnet bore threaded interface  300 . More specifically, the bonnet bore  280  is threaded and adapted to receive the packing retainer  270  which possesses reciprocal threading near its proximal end. 
         [0076]    Still further, the packing retainer  270  has a centrally located packing retainer bore  310 . The packing retainer bore is along the distal to proximal axis defined by the operator shaft  230 . Further, the packing retainer bore  310  is adapted to receive the operator shaft  230 , which travels through the packing retainer  270  and into the valve body  320 . 
         [0077]    To seal the packing retainer  270  against the bonnet  290  and to prevent pressure from leaking from the packing retainer bore  310 , the packing retainer  270  possesses numerous sealing components. 
         [0078]    To secure the actuator housing  30  to the bonnet  290  is a bonnet ring  260 . The bonnet  290 , near its distal end has a bonnet ring threaded junction  380  ultimately connecting the bonnet  290  to the actuator housing  30  via the bonnet ring  260 . Likewise, the bonnet ring  260  has internal threading adapted to receive the external threading of the bonnet  290 . In addition, the proximal end of the actuator housing  30  may have internal threading adapted to receive external threading along the bonnet ring  260 . However, it is contemplated that in certain embodiments, the actuator housing  30  may be affixed to the bonnet ring  260  by a different mechanism such as bolting, pinning and the like. Likewise, the bonnet  290  may be attached to the bonnet ring  260  by bolting, pinning and the like. 
         [0079]    The bonnet  290  as depicted in  FIG. 1  is attached to the valve body. The actuator is bolted to the valve body  320  via a series of bolts  390 . As can be seen, the operator shaft  230  is attached at its proximal end, to a valve gate  400  which sits within the valve body  320  and allows or prevents fluid from passing through the valve throughbore  410 . 
         [0080]    Referring to  FIG. 2 , the actuator of the present invention is shown in a pressurized configuration. As can be seen, the combination top shaft and piston  180  have moved in a proximal direction relative to its position as depicted in  FIG. 1 . Further, the actuator spring  240  in  FIG. 2  is in a compressed configuration relative to the uncompressed configuration as depicted in  FIG. 1 . 
         [0081]    Still referring to  FIG. 2 , the pressure chamber  120  is shown full of fluid or gas, such that the combination top shaft and piston  180  is pushed in a proximal direction. As can be seen, seal retainer  110  has seal retainer bores  210  which align with the pressure inlet  190  and the pressure outlet  200 , such that pressure in the form of a liquid or a gas may enter or exit the pressure chamber  120 . 
         [0082]      FIG. 2  further depicts the proximal polypak seal  140  in relation to the piston, the proximal polypak seal  140  is illustrative of pressure retention such that a hydraulic fluid or gas only enters and exits through the seal retainer bores  210  and the pressure inlet  190  and pressure outlet  200 , respectively. 
         [0083]    In implementation, fluid flows into the pressure chamber  120  through the pressure inlet  190  and a seal retainer bore  210 . In general, the fluid is pushed into the pressure chamber from an external pressure source which is attached to the pressure inlet via a pressure line. Such pressure sources may include hydraulic pumps or pressurized gas cylinders, depending on the application. The fluid will be prevented from exiting the pressure chamber  120  and the pressure outlet  200  by a plug in the pressure outlet  200  or a pressure relief valve in the pressure outlet  200 . Consequently, the pressure chamber  200 , which is the chamber formed between the seal retainer and the combination top shaft and piston  180 , will increase in volume. Thus, forcing the combination top shaft and piston  180  in a proximal direction. By forcing the piston in a proximal direction, the actuator spring  240  will become compressed by proximal movement of the downstop  220 . Further, the downstop  220  will force the operator shaft  230  to move in a proximal direction. As the operator shaft is affixed to a valve gate  400  within the valve body  320 , the valve gate  400  will also move in a proximal direction. Movement of the valve gate  400  in a proximal direction will either allow fluid to flow through the valve throughbore, or prevent fluid from flowing through the valve throughbore. 
         [0084]    Regarding the pressurization, keeping the fluid from escaping the pressure chamber  200  is accomplished by a series of polypak seals. To keep fluid from exiting the pressure chamber where the top shaft is centered with respect to the seal retainer  110  is an inner polypak seal  90  which is situated within an inner polypak groove  70  at the proximal end of the top plug  20 . To keep the fluid from exiting the pressure chamber  200  from the space between the seal retainer bore  210  and the pressure inlet  190  in a distal direction, an outer polypak seal  100  is employed. The outer polypak seal  100  is positioned within the outer polypak groove  80  at the proximal end of the top plug  20 . To keep the fluid from exiting the pressure chamber  200  from the space between the proximal end of the seal retainer  110  and the actuator housing  30 , is a proximal polypak seal  140 , which is positioned between the proximal end of the seal retainer wall  130  and the distal side of the actuator housing protrusion  150 . This same polypak seal also prevents escape of fluid from the space between the piston component of the combination top shaft and piston  180  and the inside of the seal retainer wall  130 . 
         [0085]    Further, in implementation, to move the piston from a proximal position to a distal position, the fluid filling the pressure chamber  200  is released. The pressure may be released by removing a plug in the pressure outlet, or by turning off, or otherwise reversing the pressure supplied by the external pressure source. 
         [0086]    The foregoing detailed disclosure and description of the invention is illustrative and explanatory thereof, and it will be appreciated by those skilled in the art, that various changes in the size, shape and materials as well as in the details of the illustrated construction, reliability configurations, or combination of features of the various valve actuator elements of the present invention may be made without departing from the spirit of the invention.