Abstract:
An undersea hydraulic coupling has a bleed port for seawater external to the coupling to enter the bore of the female coupling member when the male member is partially withdrawn from the female member. A ring-shaped radial seal positioned between the coupling members allows fluid to enter through the bleed port and flow into the bore, while sealing against the flow of hydraulic fluid out of the coupling. The bleed port and ring-shaped radial seal provide for seawater to fill the vacuum between the coupling members when they are separated, thereby decreasing the separation force required.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, this invention involves a hydraulic coupling having a bleed port allowing seawater to enter the bore of the female coupling member during disassembly. 
     2. Description of Related Art 
     Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with sealed fluid passageways connecting therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore at one end, and a relatively small diameter longitudinal bore at the other. The small bore facilitates connection to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore of the female member of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, fluid flow is established between the male and female members. 
     In the use of undersea couplings, the male and female members may be interconnected or disconnected while the coupling remains underwater, either manually by a diver or automatically by a diverless system such as a remote operating vehicle (ROV) as is well known to those skilled in the art. The male member and the female member are generally connected to opposing plates of a manifold and are held together by bolts or hydraulic members attached to the plates of the manifolds. The male member is commonly attached to one plate, while the female member is attached to an opposing plate so as to face the male member and align with it. The male member and female member may be attached to the manifold plates using various means, such as set screws or threads. Techniques for attaching the members to such manifold plates are well known to those skilled in the art. 
     In couplings of the foregoing type, one or both coupling members may include a poppet valve which opens to allow fluid flow, and closes against a valve seat within the coupling member to arrest the flow. Generally, the poppet valves are spring-biased to the closed position. The poppet valves each include a valve actuator which may be a nose or stem extending from the apex of the valve face along the longitudinal axis of the poppet valve. 
     Undersea hydraulic couplings of the foregoing type are connected and disconnected while subsea. In emergency situations, for example, storms, hurricanes, etc., the coupling members must be quickly disconnected and one of the members, typically the female member, removed from the subsea location. When the male member is withdrawn from the large central bore of the female member, there is a resulting low pressure area or vacuum created within the bore. The vacuum increases the difficulty of disengaging the male member from the female member of the coupling. This resistance to disengagement due to the vacuum is magnified when multiple couplings and manifold plates are disengaged. In recent years, undersea drilling and production is at increasingly greater depths, i.e., 5,000 or more feet below sea level. 
     At greater ocean depths, the hydraulic pressure of the system of which the coupling is a part must be greater. For example, the pressure of the hydraulic system typically must exceed the pressure of the hydrocarbon in the well bore. In subsea applications at increased internal pressures, it is necessary to prevent leakage of hydraulic fluid from the system while the coupling members are engaged or disengaged. Therefore, one or more seals are used for the junction between the coupling members. Specifically, elastomeric seals and pressure-energized metal seals have been used in undersea hydraulic couplings. 
     In U.S. Pat. No. 4,813,454 to Robert E. Smith III, an undersea coupling with pressure balancing ports is shown. The male member of the coupling includes at least one balancing port communicating between the leading face and outer sidewall. When the male member is sealed in relation to the annular elastomeric seal in the receiving chamber of the female member, and the poppet valves of each member are closed, the balancing port is used to bleed sea water into or out from the annulus between the coupling members. 
     In U.S. Pat. No. 5,469,887 to Robert E. Smith III, a hydraulic coupling with a pressure equalizing valve is shown between the central bore or receiving chamber of the female member and the external surface of the female member. A valve in the passage allows sea water to flow into the annulus during connection or disconnection of the male and female coupling members, thus equalizing the pressure and preventing implosion of seals during disconnection of the coupling members. 
     SUMMARY OF THE INVENTION 
     The present invention resides in a hydraulic undersea coupling of the foregoing type, including male and female members for fluid communication therebetween and a ring-shaped seal retained in the female member by a seal retainer. The female member includes a bleed port with a second ring-shaped seal to allow sea water to enter through the bleed port and flow through an annulus into the female member bore when the male member is partially withdrawn from the bore. The radial seal is positioned between the seal retainer and female member body, and prevents hydraulic fluid from escaping the coupling through the annulus and out the bleed port. The bleed port acts as a vacuum break to fill the vacuum in the bore as the male member is being removed from the female member bore. The present invention also reduces the force necessary to remove the male member from the female member bore. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein. 
     FIG. 1 is a sectional view of the male and female coupling members according to a first embodiment of the present invention with the male member partially removed from the female member bore. 
     FIG. 1A is a sectional view of the bleed port and seal according to a preferred embodiment of the present invention. 
     FIG. 2 is a sectional view of the male and female coupling members according to a first embodiment of the present invention with the male member fully inserted into the female member bore. 
     FIG. 3 is a sectional view of the male and female coupling members according to a second embodiment of the present invention with the male member partially removed from the female member bore. 
     FIG. 3A is a sectional view of the bleed port and seal according to a second preferred embodiment. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A first preferred embodiment of the present invention, shown in FIG. 1, comprises male member  10 , female member  20 , seal retainer  30  and retainer locking member  40 . When the male member is inserted into the female member receiving chamber  67 , fluid communication between the members is established. FIG. 1 is a sectional view showing the male member partially withdrawn from the female member. The male member comprises probe  45  with longitudinal bore  32  extending therethrough and poppet valve  60  slidably received in the bore. The male member also comprises handle  31  which is preferably threaded at  41  or otherwise connected to a manifold plate. The handle terminates at flange  42 . One end of the male member bore has a threaded section  21  for connection to hydraulic lines. The probe of the male member also may have one or more steps on its outer circumference, if desired. 
     Preferably, poppet valve  60  includes a valve actuator  61  extending from the apex of the valve face. The poppet valve is urged into the closed position by poppet valve spring  71 . The poppet valve spring is positioned between the poppet valve and spring collar  62 . The spring collar is held in place by clip  63  which engages the bore  32  of the male member. 
     Female member  20  includes central bore  68 , poppet valve  79  in the bore, and receiving chamber  67  for slidably receiving the male member therein. Poppet valve  79  has a conical valve face and a valve actuator  80  extending therefrom. Valve spring  78  urges the poppet valve into the closed position, and is anchored by spring collar  77  and clip  82 . At one end of the female member body is handle  69  which preferably is threaded at  81  for connection to manifold plates and the like. One end of the female member bore  68  also is provided with a threaded section  76  for connection to hydraulic lines. 
     In a preferred embodiment, the receiving chamber  67  has a first circumferential shoulder  56  which may be used for positioning a seal. Preferably, the seal is a hollow radial metal seal  57  which forms a seal between the circumference of probe  45  and the central bore of the female member when the coupling is assembled. Seal  57  has an internal cavity which is expansible in response to hydraulic fluid pressure to enhance the radial seal between the probe section  45  and the female member. Alternatively, the seal may be an elastomeric radial seal such as an O-ring, a seal having a dovetail interfit between the shoulder  56  and the seal retainer  30 , or a face-type seal for sealing with the leading face of the male member. The seal is held in place in the female member bore by seal retainer  30  which is preferably a sleeve-shaped member having an internal bore dimensioned to receive the probe section of the male member therethrough. The seal retainer  30  is held in place by retainer locking member  40  which preferably is threaded to the female member. 
     Seal retainer  30  is positioned on second circumferential shoulder  58  in the female member and may, if desired, provide slight axial compression to seal  57  to preload the seal. The outer diameter of the retainer is slightly less than the internal diameter  49  of the female member bore to form annulus  25  therebetween. The difference in these diameters should be sufficient to allow sliding insertion of the seal retainer into the female member bore, which will allow limited flow of seawater through the annulus. When the male member is partially withdrawn from the female member, seawater external to the coupling flows into bleed port  50 , through annulus  25  and into the space in the receiving chamber vacated by the probe section of the male member. 
     Seal  54  is positioned on shoulder  55  of the retainer. Preferably, seal  54  is a hollow U-shaped elastomeric seal. The seal allows seawater to flow from the bleed port and through the annulus into the bore or receiving chamber of the female member, but blocks the flow of fluid from the receiving chamber or bore into the annulus and out of the coupling through the bleed port. Thus, sea water entering through radial bleed port  50  will flow through the annulus between seal retainer  30  and the female member into receiving chamber  67  when the male member is partially withdrawn from the female member, without leakage of hydraulic fluid from the coupling. Seal  57  also allows sea water to bleed through the annulus into the receiving chamber while preventing escape of hydraulic fluid out from the junction between the coupling members. 
     In a preferred embodiment, radial elastomeric seal  43  forms a seal between the male member probe section, seal retainer  30  and retainer locking member  40 . The seal is preferably has a dovetail interfit between seal retainer and retainer locking member. 
     Optionally, additional bleed passages  52 ,  47 ,  53  may be included through the retainer  30  and retainer locking member. These additional bleed passages allow more sea water to bleed through the annular space  49  between the female member and seal retainer, and enter the receiving chamber when the male member has withdrawn partially out of the female member bore. 
     Now referring to FIG. 1A of the drawing, the bleed passage and seal are shown in more detail. When there is a vacuum in the receiving chamber or bore as the male member is withdrawn from the female member, the vacuum pulls water through bleed passage  50  and into gap or space  25  between the seal retainer  30  and the female member bore  49 . Elastomeric seal  54  which is positioned on shoulder  55  allows the sea water to bleed past it into the bore or receiving chamber  67 . Metal seal  57  which is positioned on shoulder  56  also allows the sea water to bleed past it when there is a vacuum in the receiving chamber. Optionally, bleed passages  52 ,  47 ,  53  may be used to allow additional seawater to bleed into the bore, if desired. 
     FIG. 2 shows the first embodiment with the male member fully inserted into the female member, the poppet valves of each member open, and hydraulic fluid transmitted between the coupling members. As shown, radial metal seal  57  and radial elastomeric seal  54  prevent hydraulic fluid from escaping between the male member, retainer and female member. Typically, hydraulic fluid in such a system is at pressures of 5,000 psi or more, which selves to pressure energize metal seal  57  and elastomeric seal  54 . The pressure energization helps maintain a fluid tight seal to prevent the escape of hydraulic fluid. However, when the male member has withdrawn partially from the female member bore, creating a vacuum in the bore, sea water flows past seals  54  and  57 , through the annulus between the coupling members. Accordingly, in a first embodiment, the bleed port is shown which allows sea water to bleed past the seal when the male is withdrawn from the female member, but that will prevent hydraulic fluid from leaking from the coupling. Preferably, bleeding of sea water into the female coupling bore occurs when the male member remains sealed radially with dovetail elastomeric seal  43 . Preferably, the poppet valves and valve actuators are dimensioned to allow bleeding of sea water into the female member bore only after the valves of one or both members are closed. 
     Now referring to FIG. 3 of the drawing, a second preferred embodiment is shown. In this embodiment, a two-piece seal retainer comprises first retainer part  90  and second retainer part  91 . Seal  54  is seated on shoulder  95  of second part  91 . In a preferred embodiment, an O-ring or other seal  92  is held in place between the first part and second part of the seal retainer. Bleed passage  25  extends between the receiving chamber and outer circumference of the female member. Optionally, additional bleed passage  94  may extend radially through the second part of the seal retainer, and bleed passage  93  may be included in the first part of the retainer, which communicates with bleed passage  53  in the retainer locking member  40 . The other components of the second preferred embodiment are the same or similar to the first embodiment. 
     In FIG. 3A, a more detailed view of the coupling according to a second preferred embodiment is shown. The first part  90  and second part  91  of the retainer are both held in place by retainer locking member  53 . The embodiment of FIG.  3  and FIG. 3A assists in positioning and assembly of elastomeric seal  92  on shoulder surface  95 . 
     The bleed port of the present invention acts as a vacuum break to prevent a vacuum in the female member bore or receiving chamber as the male is being removed from the female member. The invention reduces the force necessary to remove the male from the female member, especially in subsea conditions and/or where multiple coupling members are simultaneously disconnected. The invention of the present invention may be used or incorporated into virtually any coupling which has elastomeric or metal seals or any combination thereof, but is most advantageous in subsea hydraulic couplings of the foregoing type. 
     Although variations of the embodiment of the present invention may not each realize all of the advantages of the invention, certain features may become more important than others in various applications of the device. The invention, accordingly, should be understood to be limited only by the scope of the appended claims.