Abstract:
An undersea hydraulic coupling member is disclosed having a primary poppet valve and a secondary poppet valve to improve reliability against leakage when the coupling members are separated. A spring extends between the first poppet valve and the actuator for the second poppet valve. The secondary poppet valve remains closed unless the first poppet valve is fully opened, so that debris or other material that could prevent sealing of the first poppet valve will not cause leakage of hydraulic fluid through the second poppet valve.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves an undersea hydraulic coupling member with a primary poppet valve and a secondary poppet valve for higher reliability against leakage when the coupling is not mated. 
     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 soft seals positioned within the female member to seal the junction between the male and female members. The female member is generally 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 connections to hydraulic lines, while the large bore contains soft seals and receives the male portion of the coupling. The male member includes a cylindrical portion, or probe, at one end having a diameter approximately equal to the diameter of the large bore of the female portion 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 the various embodiments of the device, the soft seals, or O-rings, either abut the end or face of the male member or engage the cylindrical probe wall about its outer circumference. The hydraulic fluid is then free to flow through the female and male members of the coupling and seals prevent that flow from escaping about the joint and the coupling. 
     Poppet valves may be installed in the female member and in the male member of the coupling. Each poppet valve closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part. Springs or other bias means have been used to urge the poppet valves into the normally closed position. 
     Recently, one or more pressure energized metal seals have been used in undersea hydraulic couplings of the foregoing type. For example, U.S. Pat. Nos. 4,694,859 and 5,762,106 to Robert E. Smith III, assigned to National Coupling Company, Inc. show undersea hydraulic couplings with radial metal seals that engage the diameter of the probe or male member. 
     In subsea hydraulic systems of the foregoing type, it is important to prevent or minimize leakage of hydraulic fluid from each of the couplings and hydraulic systems of which the couplings are a part. It also is important to prevent or minimize the entry of seawater into the couplings and hydraulic systems. While pressure energized metal seals have been effectively used to stop leakage when the couplings are mated, it is nevertheless possible that leakage may occur around the poppet valve of one or both coupling members when they are not mated. For example, debris external to the hydraulic system, or in the hydraulic system, may become lodged in or around the poppet valve when the coupling members are separated. If that occurs, there is a potential for leakage of hydraulic fluid through the coupling member because the poppet valve has not closed and sealed properly against the valve seat in the coupling member. 
     Leakage of hydraulic fluid from one or both coupling members poses potential serious environmental risks as well as loss of subsea system hydraulic function. Therefore, efforts have been made to reduce or eliminate leakage by assuring that the valves are closed and sealed when the coupling members are not mated. For example, U.S. Pat. Ser. No. 09/293,554 to Robert E. Smith III assigned to National Coupling Company, Inc. discloses and undersea hydraulic coupling that includes a larger spring to help urge the poppet valve closed against the seal seat and prevent or minimize leakage when the coupling members are disconnected. 
     It is desirable to provide an improved apparatus for ensuring that hydraulic fluid does not leak out of one or both coupling members when coupling members are separated. It is also desirable to provide an undersea hydraulic coupling with higher reliability for shutting off the flow of hydraulic fluid when the coupling members are disconnected subsea. 
     SUMMARY OF THE INVENTION 
     The present invention resides in an undersea hydraulic coupling of the foregoing type including a male member, or probe, having a primary poppet valve and a secondary poppet valve to provide higher reliability against leakage of hydraulic fluid when the male and female coupling members are separated. The primary, or first poppet valve is urged into the closed position by a first spring. A first valve actuator urges the first poppet valve open and compresses the first spring. The secondary poppet valve, which is urged into the closed position by a second spring, is opened by a second valve actuator in response to compression of the first spring. The first spring is connected between the first valve and the second actuator. The pair of valves may be positioned in either the male or female coupling member. The secondary poppet valve may have a larger diameter, and be positioned in a larger diameter section of the coupling member bore or, if desired, both the primary and secondary poppet valves may positioned in the same diameter 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 cross-section view of a male member of the coupling according to a first preferred embodiment of the present invention. 
     FIG. 2 is a cross-section view of a male member of the coupling according to a second preferred embodiment of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 is a cross-section view of a male coupling member  10  including a cylindrical body section  15  which terminates at shoulder  18 , and a cylindrical probe section  16 . The probe section  16  preferably has a stepped external diameter and terminates at leading face  17  of the male coupling member. The male member preferably has a cylindrical bore therethrough with a first section  21  extending to conical valve seat  24  adjacent the leading face, and a second, smaller diameter section  20  extending to conical valve seat  23 . 
     The first, or primary, poppet valve  30  of the male member is slideably positioned within the first section  21  of the bore. The poppet valve includes a cylindrical, hollow valve body with apertures  33 . The face of the valve is generally conical in shape and is dimensioned to seat and seal with valve seat  24 . First spring  32  urges the first poppet valve into the closed position against the valve seat. First valve actuator  31  extends from the first poppet valve. Preferably, the actuator  31  is a stem extending longitudinally from the apex of the conical valve face. 
     The first spring  32  extends between and connects the first poppet valve  30  and the second actuator  34 . The second actuator slides in the smaller section  21  of the bore and preferably includes a sleeve shaped body  35  with a conical face having apertures  36  and a stem extending from the apex of the conical face of the actuator. In the embodiment shown in FIG. 1, when the first poppet valve  30  is closed and sealed against the first valve seat  24 , first spring  32  urges the second actuator longitudinally to a position adjacent, or abutting, leading face  46  of the second poppet valve  40 . In the first embodiment, the second poppet valve has a diameter greater than the first poppet valve and is slideably positioned in the second section  20  of the coupling bore. The second spring  41  urges the second poppet valve  40  into the closed or sealed position against seal seat  23 . The second spring  41  is anchored by spring collar  42  which is held by clip  44  in the wall of the second section  20  of the bore. In the first embodiment, the second spring  41  has a greater diameter and a greater force constant then the first spring  32 . 
     When the coupling member according to the first embodiment of the invention is mated with the opposing coupling member, first actuator  31  is moved axially or longitudinally to open the first poppet valve  30  and compress the first spring  32 . Compressing the first spring moves the second actuator longitudinally or axially against the leading face  46  of the second poppet valve to urge the second poppet valve off valve seat  23  This compresses the second spring  41 . When the second poppet valve  40  opens, it slides axially until it touches the spring collar  42 . 
     As shown in the first embodiment, the second poppet valve remains sealed to prevent leakage of hydraulic fluid unless the first poppet valve is fully opened. For example, the first poppet valve may be open slightly, and will not be sealed, due to debris lodged in the space between the first poppet valve and valve seat. If this occurs, the second poppet valve will be sealed to prevent leakage of hydraulic fluid through the coupling member and remain sealed unless the first actuator urges the first poppet valve open and the first spring, between the first poppet valve and the second actuator, is compressed sufficiently to open the second poppet valve. The second poppet valve remains closed and sealed even if there is leakage because the first poppet valve is slightly open. 
     In a second preferred embodiment of the present invention, the second poppet valve is positioned within a sleeve in the coupling member bore. As shown, male coupling member  50  has a body section  52  and a probe section  53  terminating at leading face  54 . The internal bore has a first section  57  and a second section  56  having a diameter greater than the first section. Conical valve seat  58  is located adjacent the leading face  54 . First poppet valve  59  slides within the first section  57  of the bore and has an actuator  60  extending from its conical face. First spring  61  urges the first poppet valve into a closed position against seat  58 . The first poppet valve has valve body aperture  62  extending there through. First spring  61  is connected between the first poppet valve  59  and the second actuator  63 . The second actuator  63  has a sleeve shaped body  64  and a conical face with apertures  65  and a stem extending therefrom to abut or touch the face  71  of the second poppet valve. As in the first embodiment, the second actuator may abut or be spaced from the face  71  of the second poppet valve when the first poppet valve is sealed. 
     The large diameter section  56  of the bore terminates at shoulder  66 . Preferably, an O-ring  74  or other seal seals the junction between the shoulder  66  and the sleeve  73 . The sleeve  73  has an internal bore for receiving the second poppet valve  67  which, in the normally closed position, seals with second valve seat  75  which is preferably conical in shape. The second poppet valve is urged against seat  75  by second spring  69  which is held in place by spring collar  72  and clip  70 . In the embodiment of FIG. 2, the sleeve  73  is held in the second section of the bore by threads  76 . 
     Accordingly, the second embodiment of the invention provides an assembly that is insertable into the bore of the coupling member, allowing both the first and second poppet valves to be the same size to reduce the axial force to open the poppet valves in certain applications. As in the first embodiment, the secondary poppet valve remains closed to prevent leakage through the coupling, unless the first poppet valve is fully opened and the first spring is fully compressed. The invention improves the reliability of subsea hydraulic coupling members and prevents leakage by providing a backup or secondary poppet valve. If debris or other material prevents the first poppet valve from fully closing and sealing against the valve seat, the secondary or backup poppet valve remains closed to prevent leakage of hydraulic fluid or entry of seawater into the hydraulic system of which the coupling is a part. The present invention may be used in either the male or female coupling member or both coupling members if desired. 
     Although variations in 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.