1. Field of the Invention
The present disclosure relates to tube joints, and more particularly to tube joints seals for coupling misaligned tube end portions, for example in leak tight systems.
2. Description of Related Art
Metal tubing is used to convey fluids in vehicles systems. Typically, tube segments join one another at tube joints for purposes of placing vehicle components in fluid communication with one another. These tube segments are typically formed and cut to a predetermined length, connected to one end of a vehicle module, and coupled together at their ends in a welded joint or fitting.
Owing to any of a number of sources of variation, tube ends can be axially misaligned at the tube joint such that the axes of the opposing tube segments are oblique with respect to one another. In such circumstances, the tube segment ends are simply realigned by forcing the cantilevered tube ends into axial alignment for purposes of joining the tube ends—particularly when the angular misalignment is relatively small. Realigning tube segment ends this way can impose stress on the tubing wall in one or both of the tube joint and tube joints opposing the misaligned tube joint. This stress can fracture the tube wall. It can also weaken the tube wall such that, while it may pass an initial qualification test, it is more likely to fail during service. Additionally, this misalignment can cause the joint to leak, even when a seal is included as part of the assembly.
Conventional tube segment joining methods and devices have generally been considered satisfactory for their intended purpose. However, there is a need for improved tube joining methods and devices that can correct tube segment misalignment with less stress imposed on the tube wall and improved probability of creating a leak tight connection upon initial assembly. There is also a continuing need for tube segment joints that are easy to make and use. The present disclosure provides solutions to these needs.
A seal assembly for accommodating misaligned conduits includes a first conduit, a second conduit, and a cup member. The first conduit has a first and an opposed second end with a core defined on the second end. The core defines a spherical portion with two separate seals axially spaced apart from one another relative to a longitudinal axis defined by the first conduit. An internal passage extends through the first conduit from the first end to the second end. The second conduit has opposed first and second ends with a first socket portion defined on the first end. An internal passage extends between the first and second ends. The cup member defines a second socket portion that, in conjunction with the first socket portion of the second conduit, forms a socket. The core spherical portion is captured within the cup member with the seals in sealing engagement with the first socket portion. The core is free to move relative to the socket to accommodate axial misalignment in the first and second conduits.
In certain embodiments, the cup member defines a clearance bore extending axially from the second socket portion. The clearance bore can have a diameter that is greater than that of the first end of the first conduit to accommodate axial misalignment of the first conduit relative to the cup member. The cup member can define a limit on relative axial misalignment of the first conduit relative to the cup member.
In accordance with certain embodiments, the cup member is fixed relative to the second conduit. The cup member can define an axially aligned polygonal outer perimeter for engagement with a tool for rotating the cup member circumferentially on to the second conduit. The cup member can include an outer portion fixed outboard of the second socket portion. The second socket portion can be brazed to the cup member. It is also contemplated that the second socket portion can be threaded into the inner portion of the cup member.
In accordance with certain embodiments, each seal includes a seal channel defined circumferentially about the core spherical portion of the first conduit. Separate elastomeric seal rings can be disposed in each of the seal channels. The core spherical portion can be engaged within the first socket portion of the second conduit to form a ball and socket joint such that the seals are in sealing engagement with the first socket portion. The core can be free to move relative to the first socket portion to accommodate axial misalignment of the first and second conduits. Both seals can be positioned to be in sealing engagement with the first socket portion regardless of misalignment of the first conduit within the limit of the cup member.
These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.
So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:
Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a seal assembly in accordance with the disclosure is shown in
Seal assembly 10 includes a first conduit 100, a second conduit 200, and a cup member 300. First conduit 100 defines a first longitudinal axis 114. Second conduit 200 defines a second longitudinal axis 214. First and second longitudinal axes 114 and 214 obliquely intersect one another with an angular misalignment represented by angle A. Cup member 300 couples first conduit 100 to second conduit 200 so as to render each fluidly communicative with the other and redundantly sealed with respect to an environment 12 external to seal assembly 10. As will be appreciated by those skilled in the art, first and second conduits 100 and 200 can be conduit segments coaxially coupled to respective tube segments (not shown for clarity purposes), the respective tube segments being misaligned to one another. First and second conduit segments can couple to respective tube segments with fittings, welds, or brazed joints for example.
As illustrated in
Referring to
With reference to
First and second seals extend circumferentially about core 106 including first and second seal channels 116 and 118 and first and second elastomeric seal rings 400 and 402. Core 106 of first conduit 100 engages with a socket portion 206 (shown in
With reference to
With reference to
Cup member 300 defines a clearance bore 306 that extends axially away from second socket portion 302. Clearance bore 306 is open to environment 12 external to seal assembly 10 when first and second conduits 100 and 200 are coupled to cup member 300. Clearance bore 306 has a diameter 308 that is greater than that of first end 102 of first conduit 100 for accommodating axial misalignment of first conduit 100 relative to cup member 300. Cup member 300 also defines a limit 310 for restricting the relative axial misalignment of first conduit 100 with respect to second conduit 200. The extent of axial misalignment tolerable by seal assembly is a function of diameter 308, the outer diameter of first conduit 100, and distance of the arcuate surface within cupped body 216 from limit 310. Limit 310 is suitably positioned such that first and second seals remain in sealing engagement with first socket portion 206 over a range angular misalignment values.
Cup member 300 includes a female threaded segment 314. Female threaded segment 314 includes female threads that correspond to the male threads of male threaded segment 212. The threaded segment may include standard threads, such as half-inch or one-inch screw threads for example, simplifying manufacture and reducing cost of seal assembly 10. With reference to
Embodiments of the seal assemblies described above satisfy systems that require redundant seals at mating connections. Typically, redundant sealing is achieved through close alignment between mating parts with tight alignment tolerances. This entails relatively high manufacturing cost as achieving the alignment tolerance can require rework or additional assembly time. Embodiments of the seal assemblies described above are tolerant of misalignment and provide redundant sealing through a range of conduit misalignments. Embodiments of the seal assemblies include a core defining a spherical surface portion (e.g. a ball), an opposed cupped body, a cup member, and two elastomeric seal rings (a primary seal and a redundant seal) for coupling misaligned conduit segments using mating spherical surfaces defined by the core, cupped body, and cup member and grooves machined into the core spherical surface portion to accept the elastomeric seal rings. The cupped body end has an external thread that is received by the cup member. The cup member slides over at least a portion of the spherical portion of the core and threadably engages the cupped body. This brings the two mating spherical surfaces together, compresses the elastomeric seal rings, and creates redundant seals. A radial gap between the cup member and conduit coupled to the core end allows misalignment between the core on the first conduit and cupped body on the second conduit. This provides redundant sealing without requiring close alignment between mating parts which otherwise require tight tolerances and associated high manufacturing cost.
As described, embodiments of seal assembly include two seals. As will be appreciated by those skilled in the art, the seal assembly can be constructed using a single seal to achieve sealing between the conduit interiors and environment external to the conduits. As will also be appreciated, sealing (and redundant) can also be achieved with embodiments having two, three, or a greater number of seals.
In embodiments, seal assemblies described above tolerate conduit misalignment and maintain redundant sealing in space systems under operating pressures of greater than about 120 psi with leakage rates of less than about 0.00001 scc/sec of helium or oxygen. This safeguards limited supplies of gases aboard spacecraft the loss of which could jeopardize the vehicle mission or jeopardize the well-being of crew aboard the spacecraft.
The methods and systems of the present disclosure, as described above and shown in the drawings, provide for redundant sealing of misaligned conduits with superior properties including tolerance for misalignment without having realign misaligned conduit segments or requiring tight tolerances. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the spirit and scope of the subject disclosure.
This application claims the benefit of priority to U.S. Provisional Patent Application No. 61/863,643 filed Aug. 8, 2013 which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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61863643 | Aug 2013 | US |