Abstract:
A coupling assembly is provided for releasably interconnecting confronting ends of conduit members. The coupling assembly creates a self-locking, and self-bonding connection wherein locking and unlocking is achieved by a predetermined amount of rotation of a lock nut group with respect to a stationary threaded flange. The overall construction of the coupling assembly creates the rigid connection between the conduit members, yet adequate sealing between the conduit members is provided by a single sealing member.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to a coupling assembly for interconnecting two members, and more particularly, to a self-locking, self-bonding, rigid coupling assembly for interconnecting a pair of tubular conduit members wherein the coupling assembly has a releasable locking feature for connection and disconnection.  
       BACKGROUND OF THE INVENTION  
       [0002]     The owner of the current invention is also the owner of a number of previous patents for couplings used to interconnect confronting ends of fluid carrying conduits in an aircraft. These patents include the U.S. Pat. Nos. 5,871,239; 6,050,609; and 6,073,973. Characteristics common to each of the inventions disclosed in these patents are coupling devices that include a plurality of threaded members which are rotatable in a locking direction, and rotatable in an opposite unlocking direction. Locking of the couplings is achieved by locking tabs that are received in corresponding notches/reliefs. A resilient member is provided to ensure that the couplings remain in a locked position when the coupling is tightened to a predetermined extent during rotation in a locking direction. Visual indicia is provided to indicate when the couplings have been placed into locking engagement.  
         [0003]     Nadsady U.S. Pat. No. 3,669,472; Gale et al. U.S. Pat. No. 4,808,117 and Gale et al. U.S. Pat. No. 4,928,202 each disclose a coupling device in which the tightening of the coupling parts is readily accomplished, but accidental loosening is restrained by spring fingers carried by one of the coupling parts which engage indentations or notches on the other coupling part in such a manner as to favor relative rotation of the coupling parts in the tightening direction, while restraining with greater force the rotation of the coupling parts in the opposite unlocking direction.  
         [0004]     Cannon U.S. Pat. No. 3,999,825; Filippi U.S. Pat. No. 4,008,937; Mahoff U.S. Pat. No. 4,249,786 and Gale U.S. Pat. No. 4,346,428 each disclose a coupling with one or more toggle latches which snap into a positive locking position.  
         [0005]     Spinner U.S. Pat. No. 4,285,564 discloses a coaxial plug connector wherein a first ring of axially pointed teeth is provided around the circumference of a cap ring. A first connector has a ring with teeth for engaging the teeth on the cap ring. The cap ring is withdrawn axially against the force of a biasing spring when the coupling is rotated to a different position. The cap ring is released and the spring urges it into locking engagement with the tooth ring. Thus, accidental rotation of the cap ring relative to the first connector is prevented.  
         [0006]     Runkles et al. U.S. Pat. No. 4,881,760 discloses a coupling with locking tines having visible indicia for determining whether or not the tines are in locked position.  
         [0007]     Runkles et al. U.S. Pat. No. 4,900,070 discloses a coupling with spring biased rotatable locking tines.  
         [0008]     Many prior art coupling devices are specifically designed so that the couplings are able to maintain a fluid tight connection between the conduits even when the joined conduits are misaligned. These couplings typically use multiple sealing members or o-rings in at least two or more coupling components to provide some amount of resiliency in the coupling allowing misalignment. For couplings used in aircraft applications, this misalignment can be caused by live loading conditions wherein vibrations from the aircraft and other forces cause periodic shifting of the conduit members. This misalignment can also be caused by static forces, such as may be attributed to the particular orientation of the conduit members when they are assembled in the aircraft.  
         [0009]     In the construction of an aircraft, there are constraints in available spaces to run conduits for hydraulic and electrical lines. In such constrained spaces, it is very difficult to provide the necessary support brackets to support the conduits. More particularly, when it is necessary to make a connection between confronting ends of conduit members, the constrained spaces make it even more difficult to install the couplings and to provide support brackets near the couplings. Although many couplings as mentioned above have the capability to provide a sealed connection with misaligned conduits, misalignment is avoided in most all aircraft applications as a safety precaution to prevent fuel leakage for fuel lines.  
         [0010]     Therefore, there is a need for a rigid connection that can be established between confronting conduit members thereby eliminating the need for further structural support to join the conduit members, yet the connection should be lightweight, capable of transmitting shear loads between the conduit members, and of a small enough size that the coupling can fit within the constrained spaces. Additionally, it is highly advantageous to provide electrical continuity between the interconnected conduits. Electrical continuity ensures that there will not be a buildup of an electrostatic charge on a first conduit relative to the second interconnected adjacent conduit. As a result, there is no potential difference between joined conduits or between a conduit and another reference surface, thereby eliminating the creation of an electrical spark that otherwise could ignite vaporized fuel present in the conduit members.  
       SUMMARY OF THE INVENTION  
       [0011]     In accordance with the present invention, a threaded coupling assembly is provided that is self-locking, self-bonding, and provides a rigid self-supporting connection between confronting ends of conduit members.  
         [0012]     In a preferred embodiment of the present invention, the coupling is an assembly of components including a threaded flange connected to a first conduit member, a standard flange connected to a second conduit member, and a lock nut group that interconnects the standard flange to the threaded flange. In the rigid connection, a single o-ring is utilized to seal a continuous passageway through the first and second conduit members. The lock nut group connects to the threaded flange by a threaded connection, wherein the threads of the lock nut group are clocked with respect to the threads on the threaded flange. A pre-determined amount of rotation of the lock nut group with respect to the threaded flange results in alignment of locking features on the lock nut group and the threaded flange. Once aligned, the locking features snap fit into a locking engagement.  
         [0013]     The coupling creates a rigid connection. Looseness or flexibility of the connection between the first and second conduit members is limited by a number of factors. One factor is the manor by which the threaded flange and standard flange connect to their respective conduit members. Preferably, these connections are swage type connections so that stiffness and rigidness is maintained. Another factor is the interface between the standard flange and lock nut group by use of a close tolerance fit between the opening of the lock nut group that receives the standard flange. A flat washer or bushing is placed in the opening, and rotation of the lock nut group in the locking direction captures the bushing between an interior shoulder of the lock nut group and an external shoulder of the standard flange. Other factors include use of a single o-ring, and the threaded connection between the lock nut group and the threaded flange.  
         [0014]     When the coupling assembly is to be placed in the locked position, the locking features in the form of complementary peripheral facing surfaces are provided on the threaded flange and on the lock nut group so that when the lock nut group is drawn axially toward the threaded flange by rotatably threading the lock nut group, the complementary facing surfaces snap into the locked position.  
         [0015]     The complementary peripheral facing surfaces in the preferred embodiment include at least one notch or relief formed on the lock nut group, and a corresponding at least one projection or tab formed on a peripheral surface of the threaded flange The predetermined amount of rotation of the lock nut group with respect to the standard flange results in positive engagement of the tab(s) with corresponding notch(es).  
         [0016]     Visual and audio indicators may be provided to confirm positive engagement. A visual indicator in the form of an indicator stripe may be placed on the exposed peripheral surface or rim of the threaded flange that allows the user to observe whether the lock nut group has been fully installed over the threaded flange. The indicator stripe is located on the part of the rim of the threaded flange which is covered by the lock nut group once the lock nut group is fully screwed over the threaded flange. For the audible indicator, a distinct clicking sound is present due to a biased arrangement of the components within the lock nut group, wherein a nut body and a lock ring of the lock nut group are biased with respect to axial movement along the longitudinal axis. A biasing member in the form of a wave spring maintains a spring force to maintain the lock nut group in positive engagement with the threaded flange when in the locked position. The coupling is unlocked by pulling the lock nut group so that the tab(s) are disengaged from the corresponding notch(es), and then rotating the lock nut group in an opposite unlocking direction.  
         [0017]     The lock nut group includes a number of parts, to include a split retainer, a lock ring, the wave spring mentioned above, and a nut body. The split retainer is retained within the lock ring by an annular slot or shoulder formed on the interior surface of the lock ring. The wave spring resides within a specified gap between the lock ring and nut body. The wave spring is delimited in axial movement on one side by the split retainer, and is retained on the other side by an interior shoulder of the nut body.  
         [0018]     A plurality of keys or projections are formed on the interior surface of the lock ring and are placed in mating engagement with a corresponding plurality of notches or keys formed on the outer surface or rim of the nut body. Thus when the lock nut group is assembled, the lock ring is axially or longitudinally displaceable with respect to the nut body to the extent that the wave spring can be compressed and decompressed within the fixed space or gap between the lock ring and nut body.  
         [0019]     The leak proof path or passageway that is maintained between the first and second conduit members is achieved by adequate compression of the o-ring which is positioned between a facing surface of the standard flange and a facing surface of the threaded flange. Preferably, the threaded flange includes an annular slot or groove that receives the o-ring, and the facing surface of the standard flange is sized to be received within the annular groove where the o-ring resides. As the lock nut group is advanced towards the threaded flange in the locking direction rotation, the o-ring is compressed thereby creating a leakproof seal.  
         [0020]     The coupling of the present invention also maintains outstanding electrical conductivity through the entire fitting assembly to ensure that there is minimal or no static buildup across the connection between the conduit members. The use of a single o-ring member which is bypassed by metal to metal contact of numerous components of the coupling assembly ensures that there is minimal isolation of parts in the first and second conduit members. Additionally, electrical conductivity can be further enhanced by coating various elements of the coupling assembly with conductive coatings. Conductive coatings that may be used include electroless nickel or nickel Teflon coatings. One or more of the parts or elements, as necessary, can be provided with the conductive coatings. Accordingly, the coupling assembly of the present invention requires no bonding springs within the conduit members, nor does the coupling require any electrical jumpers that are normally mounted to the coupling assembly in order to ensure electrical continuity.  
         [0021]     Types of materials that can be used with the various components of the coupling assembly of the present invention include, but are not limited to, titanium based alloys, aluminum alloys, or even stainless steel alloys. Of course, the most lightweight and high strength alloys are of particular utility with regard to aircraft applications.  
         [0022]     Also in accordance with another aspect of the present invention, a method is provided for interconnecting a pair of confronting ends of conduit members. The method is particularly useful with respect to conduits used to convey fuel and hydraulic fluids. The method comprises providing a pair of confronting ends of conduit members that must be joined in a rigid connection, configuring the ends of the conduit members to include a standard flange on one end and a threaded flange on the other end, providing a lock nut group for joining the standard flange to the threaded flange, and ensuring a locking arrangement between the flanges by a locking arrangement of the lock nut group with respect to the threaded flange.  
         [0023]     Additional advantages and features of the present invention will become apparent from the detailed description which follows, taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]      FIG. 1  is an elevation or side view illustrating the primary components of the coupling of the present invention aligned along a longitudinal axis;  
         [0025]      FIG. 2  is an exploded perspective view of the components shown in  FIG. 1  aligned along the longitudinal axis;  
         [0026]      FIG. 3  is an exploded perspective view of the lock nut group of the present invention;  
         [0027]      FIG. 4  is an enlarged vertical section of an assembled lock nut group in accordance with the construction of  FIG. 3 ;  
         [0028]      FIG. 5  is an enlarged perspective view of a threaded flange;  
         [0029]      FIG. 6  is a greatly enlarged vertical section of the threaded flange of  FIG. 5 ;  
         [0030]      FIG. 7  is an enlarged perspective view of a standard flange;  
         [0031]      FIG. 8  is a greatly enlarged vertical section of the standard flange of  FIG. 7 ;  
         [0032]      FIG. 9  is a greatly enlarged vertical section of the coupling assembly of the present invention joining confronting ends of first and second conduit members;  
         [0033]      FIG. 10  is a greatly enlarged vertical section of the coupling assembly of the present invention showing the coupling assembly in an unlocked position; and  
         [0034]      FIG. 11  is an elevation or side view of the coupling assembly showing the coupling assembly in a locked position. 
     
    
     DETAILED DESCRIPTION  
       [0035]      FIGS. 1 and 2  illustrate the coupling assembly  10  of the present invention for rigidly connecting confronting ends of two conduit members.  
         [0036]     Basic or primary components of the coupling assembly include a threaded flange or first coupling member  14 , a lock nut group or second coupling member  12 , a standard flange  16 , an o-ring  18  positioned between a facing surface of the standard flange and a facing surface of the threaded flange, and a rigid connecting means or flat washer  20  that is positioned at the interface between the lock nut group and the standard flange.  
         [0037]     Assembly of the coupling assembly includes placement of the flat washer  20  within the lock nut group and alignment with the opening of the lock nut group, and positioning the lock nut group over the standard flange so that when assembled, the flat washer  20  is trapped between an exterior shoulder  17  of the standard flange and an interior shoulder  45  of the nut body  44 , as further discussed below.  
         [0038]     The o-ring  18  is received within an annular groove or recess  76  ( FIG. 6 ) formed on facing surface  74  of the threaded flange. The facing surface  82  of the standard flange ( FIG. 7 ) compresses the o-ring  18  as the lock nut group is drawn toward the threaded flange by rotating the lock nut group in the locking direction by engagement of interior threads  56  of the lock nut group with exterior threads  72  of the threaded flange. In the locked position, the pair of slots or reliefs  40  formed on the peripheral edge of the lock nut group  12  align with and engage the projections or tabs  66  formed on the rim or peripheral edge of the threaded flange.  
         [0039]     Now referring to  FIGS. 3 and 4 , the lock nut group  12  is illustrated. The lock ring  30  is characterized by an outer rim  32  that may be roughened or knurled, a rim extension  33  that extends axially away from the outer rim  32 , and one or more notches or reliefs  40  that engage corresponding projections or tabs  66  on the threaded flange when the coupling is in the locked position. Additionally, the interior surface of the lock ring includes one or more keys or projections  38  that align with corresponding key ways or slots  48  formed on the outer rim  46  of the lock nut  44 . The nut body is inserted coaxially within the lock ring so that the keys and key ways are aligned. The key ways  48  allow relative axial displacement of the lock nut with respect to the nut body, but prevent relative rotational movement between the lock ring and nut body. Lock ring  30  is attached to nut body  44  as by a split retainer  60  that is received within an annular slot or groove  34  formed on the interior surface of the lock ring  30 . The split retainer  60  is reduced in circumference by first closing the ends  61  towards one another, placing the split retainer  60  within the groove  34 , and then releasing the ends  61  whereby the split retainer returns to its undeformed state with an enlarged circumference and thereby being held within the groove  34 .  
         [0040]     The structure of the nut body  44  is further characterized as including an interior shoulder  50 , an exterior shoulder  52 , and an axial extension  54  interconnecting the interior and exterior shoulders. The inner surface of the nut group includes threads  56  which are threaded over the exterior threads  72  of the threaded flange, as further discussed below.  
         [0041]     A biasing member, shown in the preferred embodiment as a wave spring  58 , is provided for biased relative axial displacement between the lock ring and nut body. Prior to inserting the nut body in the lock ring, the wave spring is positioned over the extension  54 . Referring to  FIG. 4 , when the lock nut group is assembled, the spring  58  is maintained in the gap or space between the lock ring and the nut body. This gap or space is delimited annularly by the extension  54  and the interior surface  36  of the lock ring. This gap or space is delimited axially by the split retainer  60  and by the interior shoulder  50 . Thus in the arrangement shown in  FIG. 4 , biased axial movement is allowed between the lock ring and nut body to the extent that the spring  58  can be compressed and decompressed in the gap or space, yet relative rotational movement of the lock ring and nut body are prevented by the key and key way arrangement.  
         [0042]     Now referring to  FIGS. 5 and 6 , the particular configuration of the threaded flange is illustrated. The threaded flange  14  is characterized by a protruding rim  64 , and one or more projection tabs  66  which are spaced from one another in the same spacing as the notches  40 . In the preferred embodiment as shown, a pair of tabs and notches are present. The tabs and notches are spaced from one another approximately 180 degrees. A sleeve  68  extends axially from the rim  64  in one direction, and external threads  72  extend from the rim  64  in the opposite axial direction. The interior surface of the sleeve  68  includes a plurality of swaging grooves  70 , and the first conduit  22  preferably attached to the threaded flange as by a swaging operation wherein the free end of the conduit member is swaged with respect to the interior surface of the sleeve  68 . The threaded flange  14  further includes a facing surface  74 , and an annular groove or slot  76  that is formed on the face  74 . The annular groove  76  is sized to receive the o-ring  18 .  
         [0043]     Now referring to  FIGS. 7 and 8 , the standard flange  16  is illustrated. The standard flange  16  includes a rib  80 , a contact face or surface  82 , and a sleeve  84 . The interior surface of the standard flange also preferably includes swaging grooves  86  wherein the free end of the second conduit member  24  is preferably swaged with respect to the interior surface of the sleeve  84 .  
         [0044]     Now referring to  FIGS. 9 and 10 , the coupling assembly is illustrated when assembled.  FIG. 9  more specifically illustrates the lock nut group threaded over the threads of the threaded flange, but the lock ring has not yet snap fit into the locked position, thus, some gap g exists between the facing surface of the rim extension  33  and the tabs  66 . Accordingly, the spring is still compressed in the gap or space between the nut body and the lock ring. As also shown, the flat washer  20  is trapped between the exterior shoulder  17  of the standard flange and the interior shoulder  45  of the nut body. The o-ring  18  is positioned in the annular groove  76  of the threaded flange, and the facing surface  82  of the standard flange fits in the annular groove and compresses the o-ring thereby creating a leak proof seal. Referring to  FIG. 10 , the lock ring has been displaced by the force from the spring  58  so that the notches  40  are engaged with the respective tabs  66 .  FIG. 11  also illustrates the coupling in the locked position. The exterior threads  72  on the threaded flange and the interior threads  56  on the nut body are clocked so that a desired number of rotations of the lock nut group allows the notches  40  to snap fit in engagement with the tabs  66 . Because of the biased arrangement between the lock ring and nut body, as the lock nut group is screwed over the threads of the threaded flange, there will be a distinct clicking sound once the notches  40  engage the tabs  66 . This audible indication allows the user to know that the lock nut group has now been placed in a locking relationship. In addition to this audible sound, an indicator stripe (not shown) in the form of a florescent colored annular marking may be placed around the portion of the peripheral surface of the rim  64  that becomes covered by the lock ring when the coupling is placed in the locked position. Thus when the indicator stripe or marking disappears, this indicates to a user that the coupling is locked and ready for operation. As can also be seen in  FIGS. 9 and 10 , the rigid nature of the attachment between the conduit members is further enhanced by the close tolerance fit between the peripheral outer edge or surface  81  of the standard flange with respect to the inner circumferential facing edge  73 .  
         [0045]     It is also apparent from  FIGS. 9 and 10  that there is substantial continuous contact between the components of the coupling assembly which bypass the o-ring thereby providing an electrically conductive path that eliminates electrostatic potential between the conduit members. The path is defined by contact of the standard flange with the flat washer  20 , contact of the flat washer with the lock nut group, and contact of the lock nut group with the standard flange by the threaded arrangement. Although the o-ring  18  provides a seal between the standard flange and the threaded flange, metal to metal contact is still achieved across this sealed interface by the electrical conductive path, thereby eliminating the need for an externally mounted bonding strap that is typically used to maintain electrical continuity.  
         [0046]     When it is desired to unlock the coupling assembly, the lock ring is pulled axially away from the rim  64  of the threaded flange by grasping the outer rim  32 , and then the lock nut group is rotated in an unlocking direction thereby unscrewing the lock nut group from the threaded flange.  
         [0047]     The coupling assembly of the present invention provides a reliable and structurally stable connection. The connection is rigid thereby eliminating the need for support hangars at or adjacent the coupling. The coupling is easily installed and requires no bonding strap. The coupling assembly is easily maintained because it can be disassembled down to a component level for inspection and for component replacement as necessary.  
         [0048]     The present invention has been described with respect to a preferred embodiment; however, other changes and modifications can be made to the invention within the scope of the claims appended hereto.