Abstract:
Hydraulic valve apparatuses employing the use of multiple pistons for opening and closing gate valves are disclosed. Additionally, hydraulic valve apparatuses with a low profile and without a top shaft are disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to provisional applications 61/608,059 filed Mar. 7, 2012. 
     
    
     FIELD 
       [0002]    The present invention pertains to valves and actuators. More specifically, the present invention pertains to different configurations of hydraulic actuators which are useful in the petroleum industry. 
       BACKGROUND 
       [0003]    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. 
         [0004]    Actuators to open and close the gate valves may include manual operators, diaphragm-type operators, and hydraulic 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. 
         [0005]    In some cases, it would be desirable, when using hydraulic piston actuators, to relieve stress associated with pushing a large volume of hydraulic fluid against a single piston. Alternatively, it would be desirable to decrease the latitudinal stresses associated with pushing a single piston shaft. Still further, it may be desirable to more finely control the movement of pistons within a hydraulic actuator. 
         [0006]    Thus, there has been a long felt need in the industry to provide an improved actuator that decreases stress on the actuator, allows for fine tuning and increases long term durability. Persons skilled in the art will appreciate the present invention which provides solutions to these and other problems associated with valve actuators. 
       SUMMARY 
       [0007]    Certain embodiments of the invention pertain to an actuator for moving a valve gate between open and closed valve positions within a valve body, the actuator comprising: an actuator housing having a proximal end oriented toward a gate valve and a distal end oriented away from the gate valve; 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, and the operator shaft defining a shaft axis; a plurality of hydraulic pressure chambers aligned along the shaft axis and separated by at least one piston; a plurality of pistons, each having a piston head and each having a proximal side and a distal side, aligned along the shaft axis and capable of movement in proximal and distal directions within the actuator housing; a hydraulic fluid path connecting one hydraulic pressure chamber to another hydraulic pressure chamber, the fluid path positioned within at least one piston head; a spring having an outer diameter, the spring being capable of producing a biasing force opposing axial movement of the operator shaft toward the valve body; and wherein a change in hydraulic fluid pressure in one hydraulic pressure chamber operatively connected through the fluid path within a piston to another hydraulic pressure chamber results in movement of another piston in a proximal direction or distal direction, and wherein the pistons and the hydraulic pressure chambers are positioned within a cylinder having a hollow interior. 
         [0008]    In specific embodiments concerning the fluid path, the piston comprising a fluid path further comprises a proximal piston shaft operatively connected to the fluid path, the proximal piston shaft having a proximal end. Still further, the fluid path may continue through the proximal piston shaft and hydraulic fluid exits the proximal end of the piston shaft. 
         [0009]    In further embodiments, the actuator may comprise one or more seals surrounding the piston shaft, wherein hydraulic fluid is prevented from providing a distal force against the proximal side of the piston. In additional embodiments a hydraulic fluid separator plate surrounding the piston and positioned between the piston and the cylinder may be included. In such embodiments, the hydraulic fluid separator plate is affixed to the hollow interior of the cylinder. 
         [0010]    In still further embodiments of the invention concerning pistons, a piston not comprising a fluid path may comprise a proximal piston shaft with a proximal end affixed to the operator shaft. Still further, said piston may be operatively connected to a downstop. In embodiments of the invention concerning the downstop, the downstop may be operatively connected to the spring. 
         [0011]    In further embodiments of the invention, the spring, the operator shaft and the cylinder are enclosed within an unpressurized housing. 
         [0012]    In additional embodiments of the present invention, the actuator comprises a top shaft having a proximal end and a distal end, the distal end extending from the distal end of the cylinder. In such embodiments wherein a top shaft is contemplated, the top shaft may be affixed to a piston having a fluid path. 
         [0013]    Additional embodiments pertain to a method of moving a gate valve between an open and closed valve position by a hydraulic actuator, the method comprising: obtaining a hydraulic actuator having a plurality of hydraulic pressure chambers aligned along an axis and separated by at least one piston; the actuator further comprising a plurality of pistons, each having a piston head and each having a proximal side and a distal side, aligned along the axis and capable of movement in proximal and distal directions within the actuator; the actuator further having an operator shaft with a distal end and a proximal end, the proximal end extending through into the valve body, the operator shaft connected to a piston; applying or removing hydraulic pressure from a hydraulic fluid path, the hydraulic fluid path connecting one hydraulic pressure chamber to another hydraulic pressure chamber, the fluid path positioned within at least one piston head; and wherein applying or removing pressure moves the pistons and the operator shaft in a proximal or distal direction, and wherein the operator shaft opens or closes a gate valve. 
         [0014]    Further embodiments of the method contemplate that the piston comprising a fluid path further comprises a proximal piston shaft operatively connected to the fluid path, the proximal piston shaft having a proximal end. In such embodiments, the fluid path may continue through the proximal piston shaft such that hydraulic fluid exits the proximal end of the piston shaft. 
         [0015]    In still further embodiments of the method a piston not comprising a fluid path may comprise a proximal piston shaft with a proximal end affixed to the operator shaft. 
         [0016]    Further, in certain embodiments of the method, upon application of hydraulic pressure, the operator shaft opens or closes a gate valve. In an opposite manner, removal of hydraulic pressure, a spring being capable of producing a biasing force opposing axial movement of the operator shaft toward the valve body moves the operator shaft in a distal direction. 
         [0017]    In additional embodiments, the piston comprising a fluid path may remain stationary upon application of hydraulic pressure and a piston not comprising a fluid path moves in a distal direction. 
         [0018]    Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a cross sectional illustration of a dual piston hydraulic actuator. 
           [0020]      FIG. 2  is a cross sectional illustration of an operator shaft and valve assembly of a dual piston hydraulic actuator. 
           [0021]      FIG. 3  is a cross sectional illustration of an alternate dual piston hydraulic actuator. 
           [0022]      FIG. 4  is a cross sectional illustration of a single piston hydraulic actuator with components which may be adapted for use in a dual piston hydraulic actuator. 
       
    
    
     LIST OF REFERENCE NUMERALS 
       [0023]      10  top shaft 
         [0024]      20  polypack seals and threaded member 
         [0025]      30  cylinder 
         [0026]      40  hydraulic pressure ports 
         [0027]      50  milled slot 
         [0028]      55  pressure chamber 
         [0029]      60  polypack seal 
         [0030]      65  upper piston head 
         [0031]      70  ware bearings 
         [0032]      80  upper piston 
         [0033]      85  proximal upper piston shaft 
         [0034]      90  hydraulic fluid path 
         [0035]      93  external pressure plate seal 
         [0036]      95  internal pressure plate seal 
         [0037]      97  separator plate bolts 
         [0038]      100  separator plate 
         [0039]      103  lower pressure chamber 
         [0040]      105  separator plate bores 
         [0041]      110  lower piston 
         [0042]      112  lower piston head 
         [0043]      114  proximal lower piston shaft 
         [0044]      118  lower piston sleeve 
         [0045]      120  spring retainer ring 
         [0046]      122  lower piston sleeve retainer ring 
         [0047]      124  housed region of the cylinder 
         [0048]      130  downstop 
         [0049]      140  central spring 
         [0050]      150  threaded bore 
         [0051]      160  housing 
         [0052]      170  bonnet ring 
         [0053]      180  bonnet ring bore 
         [0054]      200  bonnet 
         [0055]      210  valve assembly 
         [0056]      220  bonnet bore 
         [0057]      230  packing retainer 
         [0058]      240  operator shaft 
         [0059]      300  top plug 
         [0060]      310  lower cylinder 
         [0061]      320  threaded joint 
         [0062]      325  hydraulic pressure ports 
         [0063]      330  upper pressure chamber 
         [0064]      340  hydraulic pressure path 
         [0065]      350  upper piston 
         [0066]      360  lower pressure chamber 
         [0067]      370  lower piston 
         [0068]      400  single piston 
         [0069]      410  threaded partial bore 
         [0070]      420  operator shaft 
         [0071]      430  downstop 
       DETAILED DESCRIPTION 
       [0072]    Introduction 
         [0073]    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. 
         [0074]    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 3rd Edition. 
         [0075]    Distal, in certain instances, can be defined as toward the top of the actuator and away from any valve on which the actuator rests. 
         [0076]    Proximal, in certain instances, can be defined as toward a valve on which an actuator is mounted and away from the top of the actuator. 
         [0077]    Stainless steel, in certain instances, can be defined as any iron alloy generally resistant to oxidation. 
         [0078]    Hydraulic, in certain instances, can be defined as a fluid which can be placed under pressure in order to move parts of mechanical devices. Examples of hydraulic fluids include, but are not limited to water, oils, colloidal suspensions, alcohols and the like. Commercially available hydraulic fluids are readily available. 
         [0079]    Referring to  FIG. 1 , the actuator has a top shaft  10  slidably disposed in a cylinder  30  where the top shaft  10  is sealed with a polypack seals and a threaded retainer  20 . 
         [0080]    A typical cylinder  30  can be between about  10  inches to about  30  inches in diameter. The shape is generally cylindrical and can be made from strong metal alloys, ceramics and the like. In preferred embodiments, the cylinder is made of stainless steel with about a ¼ to ½ inch thickness. 
         [0081]    Still further as illustrated in  FIG. 1 , the cylinder  30  has hydraulic pressure ports  40 . Optionally, one of the hydraulic pressure ports is sealed with a bust disc. The burst disc may be set at a pressure necessary to both result in pushing of the piston downward but yet avoiding damage due to too much pressure within the hydraulic fluid path  90  as discussed below. For instance, the burst disc may be set at a pressure of 50 psi, 100 psi, 200 psi, 300 psi, 400 psi, 500 psi, 600 psi, 700 psi, 800 psi, 900 psi, 1000 psi, 2000 psi, 4000 psi, 5000 psi, 6000 psi, 7000 psi, 8000 psi, 9000 psi 10,000 psi or greater or some amount in between the aforementioned pressure points. 
         [0082]    Below the hydraulic pressure ports  40 , is the flanged region of the top shaft which is held to the upper piston  80  by way of a milled slot  50 . As can be viewed by the  FIG. 1  illustration, the upper piston fits within the cylinder  30  and abuts the inner walls of the cylinder  30 . In alternative embodiments, the flanged region of the top shaft can be bolted, or secured via a threaded nut capable of threading into the piston and retaining or securing the flanged region of the top shaft. 
         [0083]    The top shaft can be generally large enough in diameter to prevent buckling under stresses when loaded by a manual override or hydraulic overrides. 
         [0084]    Polypack seals  60  and ware bearings  70  help make the upper piston both sealed within the cylinder  30  and slidably disposed within the cylinder  30 . 
         [0085]    With detail being drawn to  FIG. 1 , the upper piston  80 , may be comprised of an incompressible material capable of moving a valve or other piston upon pressure from the upper pressure chamber  55 . Typical materials which are envisioned to be used in the construction of the upper piston  80  include stainless steels, durable ceramics and the like. The upper piston  80  typically possesses an upper piston head  65  and a proximal upper piston shaft  85 , extending in a proximal direction from the upper pressure receiving region. 
         [0086]    The upper piston  80  extends in a proximal direction with the upper piston shaft  85  as discussed above. The upper piston  80  further comprises a hydraulic fluid path  90  which allows hydraulic fluid to flow from the upper pressure chamber  55 , through the upper piston  80  and the proximal upper piston shaft  65  and into the lower pressure chamber  105 , which causes hydraulic fluid to not only accumulate above the upper piston  80 , but also between the upper piston and the lower piston  110 . 
         [0087]    A separator plate  100  with pins prevents hydraulic fluid from the lower pressure chamber from traveling distally to the upper piston. This prevents an upward or distal force acting against the upper piston when an operator is attempting to move one or both pistons in a proximal direction. The separator plate possesses at least one external pressure plate seal  93  and at least one internal pressure plate seal  95  which contacts the proximal upper piston shaft  65 . Typically these seals are polypack seals or o-rings. In general, the separator plate  100  is affixed to the inner bore of the cylinder  30 . The method of affixing the separator plate to the cylinder  30  may include welding, riveting, pinning or in preferable embodiments through the use of a plurality of separator plate bolts  97 . In general, the separator plate bolts  97  will extend through the cylinder in a substantially horizontal position which is perpendicular to the axis of the upper piston shaft  85 . The separator plate bolts  97  may be threaded and the separator plate  100  may have separator plate bores  103  which are also threaded and adapted to receive the separator plate bolts. The separator plate and seals are intended to prevent hydraulic fluid from exiting the proximal piston upper piston shaft  85  and traveling in a distal direction to the upper piston head  65  and applying unwanted pressure which would prevent the upper piston head from traveling in a proximal direction. 
         [0088]    Still referring to  FIG. 1 , like the upper piston  80 , the lower piston  110  is slidably disposed within the cylinder  30 . The lower piston  100  comprises a lower piston head  112  and a proximal lower piston shaft  114 . However, unlike the upper piston  80 , the lower piston  100  does not possess a hydraulic fluid path  90 . Like the upper piston  80 , the lower piston  110  can be made out of any hard durable material such as stainless steels, durable ceramics and the like. Regarding the lower piston head  112 , between the cylinder  30  and the lower piston head  112  are polypack seals  60  and ware bearings  70 . Typically, indentations in the lower piston head are designed to accommodate polypack seals  60  and ware bearings  70 . These enable movement of the lower piston  110  upon pressure from the upper piston  80  or the lower pressure chamber  105  without leakage of hydraulic fluid. 
         [0089]    Regarding the lower piston  110 , the lower piston shaft  114  possesses a lower piston partial bore  150  at its proximal end. The lower piston partial bore  150  is adapted to receive an operator shaft. Typically, the lower piston is a threaded bore adapted to receive a threaded operator shaft. However, it is conceivable that the operator shaft may be affixed to the lower piston shaft  114  in a different manner. 
         [0090]    At least partially surrounding the proximal lower piston shaft  114 , and with an outer diameter less than the inner diameter of the cylinder  30 , is a lower piston sleeve  118 . Downward or proximal movement of the lower piston  110  due to hydraulic pressure or pressure from the upper piston  80  in turn forces a downward or proximal movement at the junction between the lower piston head  112  and the lower piston sleeve  118 , resulting in a downward or proximal movement of the lower piston sleeve  118 . 
         [0091]    The lower piston sleeve  118  is in physical connection with the lower piston sleeve retainer ring  122 . Also in physical connection with the lower piston sleeve retainer ring  112  is the downstop  130 . The downstop  130 , like the lower piston sleeve, can be made of any rigid durable material such as stainless steel or a ceramic. Further, the outer sleeve has an inner diameter greater than the outer diameter of the housed region of the cylinder  124  contained within the actuator housing. The outer sleeve at least partially surrounds the housed region of the cylinder  124 . Still further, as the downstop abuts or is in physical connection with the lower piston sleeve retainer ring  122  at its proximal end, it is also in physical connection with an upper spring retainer ring  120  at its distal end 
         [0092]    The central spring  140  possesses a distal end and a proximal end. The distal end of the central spring  140  contacts the spring retainer ring  120 , while the proximal end of the central spring contacts the bonnet ring  170 . The cylinder, spring and downstop are housed in an actuator housing  160 . The actuator housing is preferably made of a rigid material such as a stainless steel. Further, the actuator housing  160  extends, at its proximal end, past the bonnet ring  170  such that the outer diameter of the bonnet ring  170  is less than the inner diameter of the actuator housing  160 . In such embodiments, the actuator housing may be bolted to the bonnet ring or threaded to the bonnet ring. The bonnet ring further possesses a bonnet ring bore  180 . 
         [0093]    The bonnet ring bore is adapted to receive a bonnet  200  as illustrated in  FIG. 2  is preferably connected to a valve assembly  210 . The bonnet ring bore  180  of  FIG. 1  is preferably threaded and adapted to receive reciprocal threading on the bonnet  200  of  FIG. 2 . The bonnet also possesses a bonnet bore  220  adapted to receive an internal packing retainer  230 . The bonnet bore is preferably threaded and adapted to receive reciprocal threading on the exterior of the packing retainer  230 . The packing retainer also has a packing retainer bore through which the operator shaft  240  may extend from the lower piston to the valve assembly  210  of  FIG. 2 . 
         [0094]    An alternate embodiment of the present invention is illustrated in  FIG. 3  wherein the cylinder is separated into a top plug  300  and a lower cylinder  310 . In this embodiment, the top plug  300  is threaded into the lower cylinder at a threaded joint  320 . Like the previous embodiment, hydraulic pressure ports  325  present. Also, like the previous figure, the upper piston possesses an upper pressure chamber  330 , a hydraulic pressure path  340 , an upper piston  350 , a lower pressure chamber  360  and a lower piston  370 . The lower piston can be adapted to manipulate a downstop and an actuator spring as well as an operator shaft in a fashion similar or equivalent to that illustrated in  FIG. 1 . 
         [0095]      FIG. 4  is an illustration of a single hydraulic piston actuator. However, this actuator has certain elements that may also be found in the dual piston actuator. Namely, the single piston  400 , possesses a threaded partial bore  410  adapted to receive an operator shaft  420 . The piston is further in communication with a downstop  430  to compress the spring. 
         [0096]    All of the apparatuses and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the apparatuses and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain components which are both structurally or functionally related may be substituted for the components described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.