Patent Application
20070164566
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
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
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
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.
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.
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.
U.S. Provisional Application No. 60/760,100 for this invention was filed on Jan. 19, 2006 for which the inventor claims domestic priority.
| Number | Date | Country | |
|---|---|---|---|
| 60760100 | Jan 2006 | US |
