Abstract:
A self-locking fluid coupling, utilized to connect two fluid conduits together, does not require the lockwiring of the coupling nut to prevent the rotation of the coupling nut. The locking mechanism comprises a rotational locking means on a ferrule member. The rotational locking means engage one or more inwardly protruding engagement members of the B-nut. The engagement of the rotational locking means of the ferrule with the engagement members of the B-nut creates resistance to circular motion, thereby resisting rotation of the B-nut and eliminating the requirement for lockwire to resist rotation of the B-nut.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     U.S. Provisional Application No. 60/760,100 for this invention was filed on Jan. 19, 2006 for which the inventor claims domestic priority. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention is broadly directed to a locking assembly for fastening two fluid-transmitting conduits together and, more particularly, to an improved fluid coupling assembly for providing a compression sealed joint that can maintain its preload characteristics without the utilization of lock wire or other externally applied devices or chemical compositions.  
         [0003]     Numerous devices have been utilized to retain the mechanical coupling of fluid-transmitting conduits during use. As is well known, application of stress, vibration, movement, etc. to a coupled connection can cause a loosening and release of a desired seating torque between a pair of fluid-transmitting conduits which have been coupled together. A typical method of connecting two adjacent fluid-transmitting conduits is to utilize a threaded coupling, wherein each respective end of the conduit is attached to a component of the coupling apparatus. The seals of the coupling apparatus are thereafter preloaded by making up the threaded connection between the components of the coupling. However, it is known that various phenomena such as vibration, flexing, or other cyclical or dynamic loading can cause such couplings to work loose potentially resulting in fluid release. Numerous methods and apparatus have been utilized to inhibit the loosening of the coupling after it has been preloaded, including lockwire and adhesive materials have been used to prevent the loosening of the coupling.  
         [0004]     The loosening of the connection can be a particular problem for pneumatic and hydraulic connectors, which are not only subjected to external vibrations and stresses, but also subjected to internal pressure stresses from the fluid that is being conducted through the sealed joint. In past practice in the aircraft industry, a substantial number of fluid coupling joints have consisted of compression fittings secured together with threaded connections, where a nut is lock wired to a mating connecting component in such a manner that the nut cannot turn with respect to the fitting to ensure against loss of fluid tightness in the sealing joint. However, fluid coupling joints are frequently located in areas where vision can be obscured, and the assembling of the joints must be made out of the direct vision of the worker. In such events, lock wiring is an unsatisfactory means of securing the joint against subsequent loosening. As can also be appreciated, inspection of the joint to ensure its integrity is often compromised. In addition, the lock wiring process can be time consuming. It usually requires drilling a hole in one or more corners of the nut (referred to as B-nut in hydraulic and pneumatic applications) and securing the wire to a boss or other tie-down structure to secure the tie-wire. Moreover, the lock wired connection can cause damage to equipment, and injury to personnel because of the twisted wire ends which easily snag on fabric, equipment, and skin.  
         [0005]     While various other lockwireless coupling assemblies have been disclosed, many of these require multiple or complicated parts to achieve the locking of the connection. Many of these assemblies provide for a lock between the connector and the B-nut. The connector length typically has to be increased to incorporate the locking feature. The increased length of the connector results in increased weight of the coupling, and can also complicate the installation where space is limited.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention is directed to a self-locking fluid coupling which eliminates the need for lockwiring the coupling nut while providing ease of installation and good torque resistance, and without requiring detachable locking mechanisms such as locking clips or pins or requiring special tools for assembly. The coupling is utilized to connect two fluid conduits together. An internal ferrule member comprises means for preventing the rotation of the nut member of the coupling once the nut member has been made up in sealing engagement with the connector. Among other forms of rotational locking mechanisms, the means for preventing the rotation of the nut member may comprise a plurality of serrations on the ferrule member wherein one or more of the serrations are engaged by complimentary locking means in the nut member, such as one or more inwardly protruding engagement members. The engagement of the serrations of the ferrule with the engagement members of the nut member creates resistance to circular motion, thereby resisting rotation of the nut member and eliminating the requirement for lockwire to resist rotation of the nut member.  
         [0007]     An embodiment of the coupling comprises a ferrule member, a connector member, and a nut member in cooperative engagement, wherein each of these components comprise axial passageways for passing fluid. The ferrule member is adapted at one end to receive and non-rotationally attach to a first fluid conduit. The other end of the ferrule member, identified herein as the first engagement end, has a sealing surface which, when the coupling is engaged, seals against an opposite facing sealing surface on the connector member. The ferrule member further comprises means for rotationally locking the nut member with respect to the ferrule member. Such rotational locking means may comprise a plurality of axially extending and circumferentially spaced serrations disposed between the end receiving the first fluid conduit and the engagement end.  
         [0008]     The connector member is adapted at one end to receive a second fluid conduit. The opposite facing end of the connector, identified herein as the second engagement end, comprises a sealing surface which is adapted to seal against the first sealing surface of the ferrule member. The connector member comprises fastening means disposed adjacent to the second engagement end.  
         [0009]     The nut member internally receives the first engagement end of the ferrule member, the second engagement end of the connector member, and the rotational locking means of the ferrule member. The nut member comprises fastening means, such as threads, which are adapted to engage the fastening means of the connector member. When the nut member is fully made up with the connector member, the sealing surface of the ferrule member is brought into sealing engagement with the sealing surface of the connector member to prevent leakage across the seal. The nut member may further comprise cantilever members which provide a platform for locating locking means for engaging the serrations of the ferrule member. Between adjacent cantilever members are openings which may facilitate visual confirmation that the serrations of the ferrule member are engaged within the nut member thereby resisting the rotation of the nut member.  
         [0010]     The locking means of the nut member may comprise at least one inwardly protruding lock engagement member disposed on a cantilever member, wherein the lock engagement member is adapted to engage the serrations of the ferrule member when the nut member is made up in full engagement with the connector member and the sealing surface of the ferrule member is brought into sealing engagement with the sealing surface of the connector member to prevent leakage across the seal. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a perspective view of an embodiment of the disclosed coupling.  
         [0012]      FIG. 2  is a side view of an embodiment of the disclosed coupling.  
         [0013]      FIG. 3  is a view from the connector end of an embodiment of the disclosed coupling.  
         [0014]      FIG. 4  is a view from the b-nut end of an embodiment of the disclosed coupling.  
         [0015]      FIG. 5  is an exploded view of an embodiment of the disclosed coupling.  
         [0016]      FIG. 6  is a front view of an embodiment of the b-nut showing a possible configuration of the inwardly protruding lock engagement members.  
         [0017]      FIG. 7  is perspective view of an embodiment of the disclosed coupling in an elbow configuration.  
         [0018]      FIG. 8  is a sectional view of the embodiment shown in  FIG. 7 .  
         [0019]      FIG. 9  is a view from the b-nut end of the embodiment shown in  FIG. 7 . 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0020]      FIG. 1  shows the basic components of an embodiment of the disclosed coupling  10  in an assembled configuration, but shown without the connecting fluid conduits. The coupling  10  comprises a nut member  12 , a connector member  14 , and a ferrule member  16  which is only partially shown in  FIG. 1 . As shown in  FIG. 2 , the coupling  10  is utilized to connect fluid bearing conduit members which may be disposed in an opposite facing configuration as shown in  FIG. 2 , that is, where the fluid bearing conduit members are in axial alignment. An alternative embodiment, as shown in  FIG. 7  through  9  may be utilized in which the fluid bearing conduit members are in a ninety-degree configuration.  
         [0021]     First fluid conduit  18  is connected by the coupling  10  to a second fluid conduit  20 . The second fluid conduit  20  is attached and sealed to connector member  14  by means known in the art, such as by welding, dynamic seal beam, flaring, flareless connection, crimping, swaging, lock ring, or other means known to those skilled in the art, which may utilize counter-bores, shoulders, or other internal structures within the connector member corresponding with the attachment means of the second fluid conduit  20 .  
         [0022]     The first fluid conduit  18  is likewise attached to ferrule member  16  and coupled with the nut member  12  such that the end of the ferrule member extends through the end of the nut member. The attachment means utilized for attaching ferrule member  16  to first fluid conduit  18  must not allow rotation of the ferrule member  16  with respect to the first fluid conduit  18 . The coupling  10  must be configured such that when the coupling is made up to connect the two fluid conduits together, a leak-tight seal is created between a first seal face  22  of the ferrule member  16  and a second seal face  24  of the connector member  14 . This type of seal, comprising a frusto-conical section in one seal face and matching surface in the opposing seal face is a dynamic seal wherein increased pressure of the fluid within the passageway works to increase the sealing force between the seal faces.  
         [0023]     Ferrule member  16  is generally cylindrical, having an opening extending through its entire length, where the opening is oriented along the longitudinal axis of the ferrule member. The ferrule member  16  is adapted at one end, designated first end  26 , to receive and non-rotationally attach to the first fluid conduit  18 . The other end of the ferrule member  16 , identified herein as the first engagement end  28 , comprises first seal face  22 . Ferrule member  16  further comprises rotational locking means for preventing the rotation of the nut member  12  once the nut member is made up to the connector member  14  and a leak-tight seal is created between the first seal face  22  of the ferrule member  16  and the second seal face  24  of the connector member  14 . The locking means may comprise various interlocking structures located on the ferrule member  16  and the nut member  12  which engage once the nut member is fully made up to the connector member  14 , such as a keyway and spline combination, or similar types of structures.  
         [0024]     The locking means may also comprise, as shown in the Figures, a plurality of axially extending and circumferentially spaced serrations  30  disposed on the ferrule member  16  between the end  26  receiving the first fluid conduit  18  and the engagement end  28 , wherein one or more inwardly protruding lock engagement members  44  of the nut member  12  engage the serrations  30 . The serrations  30  may be configured such that the side of each serration facing the first engagement end  28  forms a right angle with respect to the longitudinal axis of the ferrule member  16  and the side of each serration facing the conduit receiving end  26  forms an angle of 45 degrees or less with respect to the longitudinal axis of the ferrule member.  
         [0025]     While the number of serrations  30  may vary, it has been found that a configuration wherein the number of serrations varies from a range of 14 to 60 serrations circumferentially disposed about the ferrule member  16  is preferable. Ferrule member  16  may comprise various materials known to those practicing in the art, including plastics, composites, or high strength metal alloys, such as titanium.  
         [0026]     Connector member  14  comprises a second conduit receiving end  32  adapted to receive and attach to a second fluid conduit  20 . Opposite second conduit receiving end  32  is second engagement end  34 . Second engagement end  34  comprises a second seal face  24  which is adapted to seal against the first seal face  22  of the ferrule member  16 . The connector member  14  further comprising fastening means, such as external threads  36  which are disposed adjacent to the second engagement end  34 . As also shown in the figures, connector member  14  may comprise wrench flats  38  to facilitate making up the connector member  14  to the nut member  12 . As shown in  FIG. 3 , the wrench flats  38  may be configured in a hexagonal profile.  
         [0027]     Nut member (or B-nut)  12  makes up with connector member  14  such that as torque is applied to the nut member, the threads advance the nut member over the ferrule member  16  such that the nut member internally receives the ferrule member  16 . When the nut member  12  is fully made up to the connector member  14 , first end  26  of the ferrule member  16  extends out through sleeve  40  of the nut member. Nut member  12  further comprises fastening means, such as internal threads  42 , which are adapted to engage the fastening means of the connector member  14 , such as external threads  36 , and make up the connection. When the nut member  12  is made up with the connector member  14 , the first seal face  22  of the ferrule member  16  is brought into sealing engagement with the second seal face  24  of the connector member to prevent leakage across the seal.  
         [0028]     When the nut member  12  is made up with the connector member  14 , the first engagement end  28  of the ferrule member  16  and the second engagement end  34  of the connector member  14  will be internally received by the nut member. The nut member further comprises a plurality of cantilever members  48  which provide a beam for locking onto the serrations  30  of the ferrule member  16 . The number of cantilever members may vary from three to eight, with four being the preferred number. As shown in  FIG. 6 , the nut member  12  further comprises one or more inwardly protruding lock engagement members  44  located on one or more of the cantilever members  48  wherein the inwardly protruding lock engagement member  44  is adapted to engage the serrations  30  of the ferrule member  16  when the nut member  12  is made up in full engagement with the connector member  14  and the first sealing face  22  of the ferrule member  16  is brought into sealing engagement with the second seal face  24  of the connector member  14 . Between adjacent cantilever members are openings  50  which facilitate visual confirmation that the serrations  30  of the ferrule member  16  are engaged within the nut member  12  thereby resisting the rotation of the nut member  12 .  
         [0029]     As shown in the figures, nut member  12  may comprise wrench flats  46  to facilitate making up the nut member  12  to the connector member  14 . As shown in  FIGS. 3 and 4 , the wrench flats  46  of the nut member  12  may be configured in a hexagonal profile.  
         [0030]     While the disclosed coupling may be configured in a number of different dimensions, it has been found that when utilizing fluid conduits having an outside diameter ranging from 0.025 inch to 1.00 inch, a preferable range for the length of ferrule member  16  is from 0.695 inch to 0.760 inch. It has also been found that a preferable length dimension from the first end  26  to the plurality of axially extending and circumferentially spaced serrations  30  is approximately 0.20 inch, where the dimension is greater than 0.15 inch but not larger than 0.30 inch.  
         [0031]     A preferable range of lengths of connector member  14  are 0.798 inch to 1.103 inch. A preferable range of lengths of nut member  12  are 0.679 inch to 1.020 inch.  
         [0032]      FIGS. 7 through 9  show an alternative embodiment of the coupling  10 ′ which show the nut member  12 ′ attached to an elbow assembly  52 , where ferrule member  16 ′ has serrations  30 ′. Lock engagement members  44 ′ engage serrations  30 ′ of the ferrule member  16 ′, thereby resisting the rotation of the nut member  12 ′. Clip wire  54  retains the ferrule member  16 ′ within the nut member  12 ′ prior to making the nut member up to an opposite facing connector member  14  and second fluid conduit  20  (not shown), but does not prevent rotation of nut member  12 ′ to engage the threads of the connector member. In this embodiment the longitudinal axis of the first fluid conduit  18 ′ is at an angle of approximately ninety degrees of the longitudinal axis of the second fluid conduit  20 ′.  
         [0033]     While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. For example, the size, shape, and/or material of the various components may be changed as desired. Thus the scope of the invention should not be limited by the specific structures disclosed. Instead the true scope of the invention should be determined by the following claims.