Related Application

This application claims the benefit of U.S. Provisional Application No. 63/043,389 filed June 24, 2020, which is hereby incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to threaded coupling assemblies for interconnecting fluid-carrying conduits and, more particularly, to such assemblies that utilize a coupling nut in cooperation with a sealing sleeve for effecting a sealed connection between the conduits in a fully-assembled state.

Background

Threaded couplings are commonly employed to connect adjacent sections of pipes, tubing, hoses, fluid flow equipment and the like in a variety of industries and applications. One common type of threaded coupling includes a coupling nut disposed about an end of a tube for threadably engaging a fitting. The fitting may be used to connect the tube to an adjacent section of tube. Typically, the coupling nut cooperates with an abutment on the tube or ferrule to draw the tube and fitting toward each other to effect a sealing engagement. For such threaded couplings to work properly with a leak-free connection, one or more seals are provided with respect to each of the tube and fitting to seal the leak paths between these conduits when the coupling is in use under system pressure.

Summary

One problem with some conventional threaded couplings is that the seal(s) are commonly installed to provide a relatively tight sealing engagement with the tube when an end of the tube is inserted into the coupling. However, such a tight engagement may cause the seal to become damaged or displaced, thereby hindering sealing performance. An aspect of the present disclosure provides a threaded coupling having a two-stage seal groove for containing the seal ring in at least a first, low- compression stage during assembly with a fluid conduit, and which allows the seal ring to transition to a second, higher-compression stage when the threaded coupling is fully-assembled and pressurized by fluid pressure. The low- compression stage enables the fluid conduit to easily push past the seal ring without high-forces that may cause damage or displacement of the seal ring and may provide sufficient sealing engagement with the conduit to seal at low fluid pressures. As the system fluid pressure increases, the two-stage groove enables the seal ring to easily transition into the second, high-compression stage to provide greater sealing engagement with the conduit to seal at the higher fluid pressures.

In exemplary embodiments, the threaded coupling assembly also may include a stop for engaging an end of the conduit, which provides a tactile feeling to the user that indicates proper positioning of the conduit with respect to the threaded coupling assembly component(s).

According to an aspect of the present disclosure, a threaded coupling assembly is provided for interconnecting a first fluid conduit with a second fluid conduit, the threaded coupling assembly including: a coupling nut rotatable about a longitudinal axis of the first fluid conduit and having a thread for threadably coupling the first fluid conduit to the second fluid conduit; a sealing sleeve having a radially inner surface for receiving a forward end portion of the first fluid conduit, and a two-stage circumferential seal groove in the radially inner surface of the sealing sleeve, the two-stage circumferential seal groove comprising a first groove portion and a second groove portion, wherein the first groove portion has a first groove depth that is greater than a second groove depth of the second groove portion; and a seal ring disposed in the two-stage circumferential seal groove for sealingly engaging a radially outer surface of the forward end portion of the first fluid conduit; wherein the threaded coupling assembly is configured such that: (i) when the forward end portion of the first fluid conduit is inserted into the sealing sleeve, the seal ring is disposed in the first groove portion; and (ii) when the threaded coupling assembly is in a fully- assembled and pressurized state above a specified fluid pressure level, the seal ring is transitioned to the second groove portion, whereby the seal ring is pushed radially inwardly against the radially outer surface of the fluid conduit to enhance sealing performance.

According to another aspect, a threaded coupling assembly for interconnecting a first fluid conduit with second fluid conduit, the threaded coupling assembly including: a holding ring having a cutting tooth portion, a first engaging surface, and a second engaging surface, wherein the cutting tooth portion is configured to cut into and hold a forward end portion of the fluid conduit; a coupling nut engageable with the first engaging surface of the holding ring; a sealing sleeve having a radially inner surface for receiving the forward end portion of the fluid conduit, a first engagement portion for engaging the second engaging surface of the holding ring, and a circumferential seal groove in the radially inner surface of the sealing sleeve, the circumferential seal groove comprising a first groove portion and a second groove portion, and a seal ring disposed in the circumferential seal groove for sealingly engaging a radially outer surface of the forward end portion of the fluid conduit; wherein the first groove portion is configured to contain the seal ring when the threaded coupling assembly is in a fully-assembled state, such that the seal ring provides a sealing engagement against a sealing surface of the forward end portion of the fluid conduit that is sufficient to seal at a first fluid pressure level; and wherein the second groove portion is configured to receive the seal ring from the first groove portion when the threaded coupling assembly is in the fully- assembled state and pressurized to a second fluid pressure level that is greater than the first fluid pressure level, the second groove portion being configured to increase compression of the seal ring relative to compression provided by the first groove portion such that the seal sleeve provides sufficient sealing at the second fluid pressure level.

According to another aspect, a sealing sleeve for use in interconnecting fluid-carrying conduits includes: a radially inner surface for receiving a forward end portion of a fluid conduit; a circumferential seal groove in the radially inner surface of the sealing sleeve, the circumferential seal groove comprising a first groove portion and a second groove portion, wherein the first groove portion has a first groove depth that is greater than a second groove depth of the second groove portion; and a forward end portion having a radially inwardly extending abutment for engaging an end face of the forward end portion of the fluid conduit when the fluid conduit is inserted into the sealing sleeve.

The following description and the annexed drawings set forth certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features according to aspects of the invention will become apparent from the following detailed description when considered in conjunction with the drawings.

Brief Description of the Drawings

The annexed drawings, which are not necessarily to scale, show various aspects of the invention.

Fig. 1 is a side view of an exemplary threaded coupling with exemplary fluid conduits according to an embodiment of the present disclosure.

Fig. 2 is a cross-sectional perspective view of the threaded coupling and the fluid conduits in an exemplary partially-assembled state.

Fig. 3 is a cross-sectional perspective view of the threaded coupling and the fluid conduits in an exemplary fully-assembled and pressurized state.

Detailed Description

Referring to Figs. 1-3, an exemplary threaded coupling assembly 10 for interconnecting first and second fluid carrying conduits 14 and 15 is shown. As shown, the exemplary threaded coupling assembly 10 (also referred to as the threaded coupling) generally includes a coupling nut 16 and a sealing sleeve 18 that holds a seal ring 20. In exemplary embodiments, the coupling assembly 10 also includes a holding ring 22 for gripping onto the first fluid conduit 14 and cooperating with the nut 16 to apply axial force to draw the conduits 14, 15 toward each other. As will be described in further detail below, the sealing sleeve 18 includes a two-stage circumferential seal groove that contains the seal ring 20 in a first, low-compression portion of the groove during assembly of the threaded coupling 10, and which allows the seal ring 20 to transition to a second, higher-compression portion of the groove when the threaded coupling 10 is in a fully-assembled and pressurized state.

The second fluid conduit 15 may be any suitable conduit for conveying fluid such as liquid or gas. In the illustrated embodiment, the second fluid conduit 15 is a fitting 15 having an internal fluid passage 24 and an external thread 26 at a first end portion for threadably coupling to the nut 16. As shown, the fitting 15 includes a seal 28 disposed in a radial groove 30 in an end face 35 of the fitting 15 which sealingly engages with the sealing sleeve 18 to seal the fitting side of the fluid connection. In the illustrated embodiment, the fitting 15 is a straight connector with a second external thread 27 at an opposite second end portion for threadably coupling with an adjacent section conduit (not shown), such as via another threaded coupling. Other suitable fittings or conduits may be employed for use with the threaded coupling 10, such as bent or T-shaped fittings, or the second fluid conduit 15 may be a threaded pipe, or the like.

The first fluid conduit 14 may be any suitable conduit having an internal passage 31 and a forward end portion 32 that cooperates with the threaded coupling 10 for effecting a sealing engagement. In the illustrated embodiment, the fluid conduit 14 is a tube having sufficient wall thickness for withstanding fluid pressures for the desired application. The conduit 14 may be made of any suitable material, such as metal, for example copper, brass, aluminum, steel, or the like.

As shown, the coupling nut 16 is disposed about the forward end portion 32 of the conduit 14 and is freely rotatable about a longitudinal axis 33 of the forward end portion 32. The nut 16 forms a receptacle for receiving the second conduit 15 (e.g., fitting) and for containing one or more components of the threaded coupling assembly 10. The nut 16 includes internal threads 34 for engaging the external threads 26 of the second conduit 15 for effecting a sealing engagement between the conduits 14, 15, as described in further detail below. The external surface 36 of the nut 16 may have any suitable configuration for facilitating application of torque to the nut 16 to complete the threaded connection. In the illustrated embodiment, for example, the nut 16 includes a hexagonal outer surface 36 for engagement by a torque tool, such as a wrench. The holding ring 22 may have any suitable configuration for gripping onto the conduit 14 and cooperating with the nut 16 to apply axial force to the conduit 14 when the nut 16 is threadably coupled to the second fluid conduit 15. As shown, the holding ring 22 includes a radially inner surface 38 for receiving the forward end portion 32 of the conduit 14, a first engaging surface 40 for engaging the nut 16, and a second engaging surface 42 for engaging the sealing sleeve 18. In exemplary embodiments, the holding ring 22 also includes a cutting tooth portion 44 that is configured to cut into and hold the forward end 32 portion of the conduit 14 as the threaded coupling 10 is progressed to its fully- assembled state (as shown in Fig. 3, for example, and described in further detail below). In exemplary embodiments, the holding ring 22 may include a damping feature to reduce transmission of vibration to the conduit 14. In the illustrated embodiment, for example, the holding ring includes a notch 46 in the first engaging surface 40 that is configured to damp vibrations.

In exemplary embodiments, the holding ring 22 is interposed between the nut 16 and the sealing sleeve 18 such that the first engaging surface 40 for engaging the nut 16 is an axially rearward surface and the second engaging surface 42 for engaging the sealing sleeve 18 is an axially forward surface. In the illustrated embodiment, the first (rearward) engaging surface 10 of the holding ring 22 is formed with a conical shape that tapers radially inwardly. The nut 16 includes a corresponding radially outwardly tapered conical surface 41 that is configured to engage and apply axial force to the first engaging surface 40 of the holding ring 22. The nut 16 also exerts a radial force on the holding ring 22.

The sealing sleeve 18 includes a radially inner surface 48 for receiving the forward end portion 32 of the conduit 14. In the illustrated embodiment, the radially inner surface 48 of the sealing sleeve 18 includes a two-stage circumferential seal groove 50 which contains the seal ring 20. The two-stage seal groove 50 includes at least two groove portions 52 and 54 for containing the seal ring 20 in the respective groove portions 52, 54 depending on the state of the threaded coupling 10. In exemplary embodiments, the first groove portion 52 of the two-stage groove 50 is configured as a low-compression stage that enables the conduit 14 to easily push past the seal ring 20 without damaging or displacing the seal ring 20. The second groove portion 54 is configured as a higher-compression stage that enables the seal ring 20 to push with greater force against a sealing surface 49 of the conduit 14 and the sealing surface of 54 of the groove to provide sufficient sealing at higher fluid pressures.

As described in further detail below, the two-stage groove 50 is configured to allow the seal ring 20 to transition from the first stage to the second stage as fluid pressure increases beyond a certain level and moves the seal ring 20 from the first groove portion 52 to the second groove portion 54. As such, in exemplary embodiments the first groove portion 52 is located at an upstream portion of the leak path toward the fluid pressure source, and the second groove portion 54 is located at a downstream portion of the leak path away from the fluid pressure source. In the illustrated embodiment, for example, the second groove portion 54 is toward the rearward end of the sealing sleeve 18 and the first groove portion 52 is toward the forward end of the sealing sleeve 18 where the threaded coupling fluidly 10 connects the conduits 14 and 15 together.

In exemplary embodiments, the two-stage circumferential seal groove 50 includes only two groove portions 52 and 54, which provides a simple and cost- effective approach to facilitate initial assembly and full sealing capability of the threaded coupling assembly 10. As shown, a forward face 56 of the groove 50 forms an axial end surface of the first groove portion 52, and a rearward face 58 of the groove 50 forms an axial end surface of the second groove portion 54. In the illustrated embodiment, the forward and rearward faces 56, 58 each extend in a radial direction that is perpendicular to a longitudinal axis of the sealing sleeve 18. In exemplary embodiments, the inner diameter portions of the sealing sleeve 18 (e.g., formed by the radially inner surface 48) that are forward and rearward of the two-stage groove 50 are sized relative to the outer diameter of the first conduit 14 to restrict extrusion of the seal ring 20.

It is understood that although only two groove portions 52 and 54 are shown, the two-stage groove 50 may include more than two groove portions or more than two stages. Accordingly, as used herein, the term two-stage seal groove means that the seal groove 50 includes at least two stages (i.e. , two groove portions), such as only two stages, but may include greater than two stages (i.e., greater than two groove portions) as may be desirable depending on the particular application. In this manner, the two-stage seal groove 50 also may be referred to as a multi-stage groove 50. In exemplary embodiments, two or more of the groove portions (e.g., 52 and 54) of the two (multi)-stage seal groove 50 may be delineated or separated from each other by a structural feature, such as a step, ridge, detent, inclined surface or the like between adjacent groove portions (e.g., 52 and 54). For example, in the illustrated embodiment, the respective groove portions 52 and 54 each have a substantially flat bottom surface (in the radially outer depth direction), and a tapered surface 70 is provided between these flat bottom surfaces of the groove portions 52 and 54.

In other exemplary embodiments, two or more of the adjacent groove portions (e.g., 52 and 54) of the two (multi)-stage seal groove 50 may be blended together in a continuous manner. For example, the tapered surface 70 could continuously extend from the forward end face 56 to the rearward end face 58 of the groove 50, in which case the first and second groove portions 52, 54 would be respective continuous segments of the groove 50. The foregoing examples are non-limiting and exemplary, and other suitable configurations of the two (multi)-stage seal groove 50 may be provided as would be understood by those having ordinary skill in the art.

The seal ring 20 may have any suitable configuration and may be made with any suitable material for enabling movement within the two-stage seal groove 50 and effecting a fluid seal against the sealing surface 49 of the conduit 14. In the illustrated embodiment, for example, the seal ring 20 is an O-ring seal having a circular cross-section and a continuous round circumference. Other suitable seal ring shapes may include an elliptical shape, a square shape, a rectangular shape, or other polygonal shape, for example. In exemplary embodiments, the seal ring 20 is made with an elastomeric material, such as a suitable rubber, for example nitrile rubber. The material and/or shape of the seal ring 20 may be selected depending on the application parameters, including the type of fluid, temperature ranges, fluid pressures, and the like, for example.

As shown in the comparison between Figs. 1-3, the seal ring 20 may have an uncompressed shape (Fig. 1), and may be compressed by an amount depending on which portion (e.g., 52 or 54) of the two-stage groove 50 the seal ring 20 is located, as described in further detail below. As shown in the comparison of the illustrated states, the degree of compression of the seal ring 20 is a determination of how much the cross-sectional width (in the radial direction) is changed from the uncompressed state (e.g., Fig. 1) to the various compressed states (e.g., Figs. 2 and 3). The degree or amount of compression may therefore be expressed in terms of a percentage of the compressed cross- sectional radial width compared to the uncompressed cross-sectional radial width of the seal ring 20. In the illustrated embodiment, for example, the O-ring has a circular diameter when in an uncompressed state, which when compressed changes the cross-sectional radial width (distance between radially outer and inner surfaces) to make the seal ring 20 more elliptical in cross- section.

Referring particularly to Figs. 2 and 3, an exemplary method of assembling the threaded coupling assembly 10, and an exemplary operation of the seal ring 20 in the two-stage seal groove 50 will now be described in further detail. Fig. 2 shows the threaded coupling assembly 10 in an exemplary partially-assembled state, such as with a hand-tight threaded connection of the nut 16 onto the second conduit 15 (e.g., fitting), and without the cutting tooth portion 44 biting into the conduit 14. In exemplary embodiments, the sealing sleeve 18, the seal ring 20, and the holding ring 22 may be operatively coupled together to form a single assembly unit 23 (Fig. 1 ) of the threaded coupling assembly 10. For example, the second (forward) engaging surface 42 of the holding ring 22 may be operatively coupled to the sealing sleeve 18, such as with a press-fit connection, an adhesive, or other suitable connection. The seal ring 20 may be operatively coupled to the sealing sleeve 18, such as by being compressively fit into the first groove portion 52 of the two-stage groove 50. Such an assembly unit 23 enables ease of assembly of the threaded coupling 10, and also may enable some existing threaded couplings to be easily retrofit with the exemplary threaded coupling assembly 10. The pre-installation of the seal ring 20 in the first groove portion 52 also may minimize risks of incorrect installation of the seal ring 20. Such an assembly 10 also provides benefits of minimizing incorrect installation or misplacing parts compared to other types of couplings that require separate installation of a seal ring. During initial assembly, the user will insert the forward end portion 32 of the conduit 14 through the coupling nut 16, through the holding ring 22, and into the sealing sleeve 18. As shown in the illustrated embodiment, the cutting tooth portion 44 of the holding ring 22 is at a radially outward position to permit the forward end portion 32 of the conduit 14 to be slid through the holding ring 22. Also as shown in the partially-assembled state, the seal ring 20 is in the first groove portion 52 of the two-stage groove 50 where the forward end portion 32 of the conduit 14 pushes past the seal ring 20. As discussed above, the first groove portion 52 of the two-stage groove 50 is configured as a low-compression stage that enables the conduit 14 to easily push past the seal ring 20 without damaging or displacing the seal ring 20.

As shown, in exemplary embodiments the sealing sleeve 18 includes an abutment or stop 60 for engaging a forward end face 61 of the conduit 14 which provides a tactile feedback to the user that indicates proper positioning of the conduit 14 with respect to the threaded coupling assembly 10. In the illustrated embodiment, for example, the stop 60 is formed by a radially extending abutment, such as a radially inwardly extending shoulder, at a forward end portion of the sealing sleeve 18 that engages the end face 61 of the conduit 14 when the forward end portion 32 of the conduit is properly inserted into the sealing sleeve 18. Because the sealing sleeve 18, holding ring 22, and seal ring 20 are provided as an assembly unit 23 in exemplary embodiments, the stop 60 may assure proper placement of the conduit 14 with respect to each of these components.

Referring to Fig. 3, a fully-assembled and pressurized state of the threaded coupling assembly 10 is shown. From the state shown in Fig. 2 to the state shown in Fig. 3, the nut 16 is further threaded onto the second conduit 15 (e.g., fitting), such as with a torque tool. Such threaded coupling by the nut 16 causes the nut 16 to apply axial force to the first (rearward) engaging surface 40 of the holding ring 22, thereby forcibly drawing the second (forward) engaging surface 42 of the holding ring 22 slidably against a rearward engagement portion 62 of the sealing sleeve 18. In the illustrated embodiment, the rearward engagement portion 62 of the sealing sleeve 18 includes a conically progressing sliding surface that faces radially inwardly and rearwardly. As shown, the first (forward) engaging surface 42 of the holding ring 22 is radially outward and opposite the cutting tooth portion 44. In this manner, as the holding ring 22 is forcibly drawn toward the sealing sleeve 18, the cutting tooth 44 portion is pushed radially inwardly by the rearward engagement surface 62 of the sealing sleeve 18 to cut into and hold the radially outer surface of the fluid conduit 14. Such engagement between the holding ring 22 and sealing sleeve 18 may fix these components together, such as by swaging. When the holding ring 22 bites into the conduit 14, further threading by the coupling nut 16 applies axial force to the holding ring 22 which transfers this axial force to the conduit 14, thereby forcibly drawing the forward end portion 32 of the conduit 14 toward the other fluid conduit 15. Such a simple and inexpensive way of connecting the threaded coupling 10 to the conduit 14 as provided by the holding ring 22 provides advantages over many conventional flange-type fittings, in which either brazing a sleeve or using a separate tool to cold from a flange on a tube is required.

As shown in the illustrated embodiment, the holding ring 22 may include a radially outwardly extending and forwardly facing stop face 64 that is configured to engage a rearward radially extending stop face 66 of the sealing sleeve 18 when the threaded coupling assembly 10 is in the fully-assembled state. This stops further axial movement of the holding ring 22 relative to the sealing sleeve 18. In exemplary embodiments, the forward end of the sealing sleeve 18 forms a first radially extending stop face 68 which, when the threaded coupling assembly 10 is in the fully assembled state, abuts the radially extending face 35 of the other fluid conduit 15 (e.g., fitting). As shown in the illustrated state, the seal 28 in the end face 35 of the second conduit 15 is compressed to provide a sealing engagement against fluid pressure. The seal 28 may be any suitable seal, such as an O-ring seal made of a resilient material, such as nitrile rubber, for example, or may be a metal seal.

In exemplary embodiments, when the threaded coupling assembly 10 is in a fully-assembled state that couples the conduits 14, 15 together, the first groove portion 52 may be configured to provide a first compressive force that compresses the seal ring 20 sufficiently to provide sealing engagement with the conduit 14 to seal at relatively low fluid pressure levels. Such low fluid pressures may be application specific, and may be in the range from 1 psi to 1 ,0000 psi, by way of a non-limiting example, which may depend on the size of the coupling and the particular application. For example, in a hydraulic application, the low pressure operating range may be 1 ,000 psi or less; whereas in a pneumatic (e.g., air) application, the low pressure operating range may be 100 psi or less.

To provide such sealing engagement while also enabling installation of the conduit 14 without displacive or damaging force on the seal ring 20, in exemplary embodiments the first groove portion 52 is configured to compress the seal ring 20 in a range from 5% to 15% (compressed size of the seal ring 20 compared to uncompressed size in terms of change in cross-sectional radial width, as discussed above). More particularly, the first groove portion 52 may be configured to compress the seal ring 20 in a range from 8% to 15% (compressed size of the seal ring 20 compared to uncompressed size), such as 8%, 10%,

15%, etc., including all ranges and sub-ranges between the stated values, for example.

As the fluid pressure in the threaded coupling 10 increases beyond a specified level, the two-stage groove 50 is configured to allow the seal ring 20 to transition from the first groove portion 52 (i.e. , first stage) to the second groove portion 54 (i.e., second stage). The specified pressure level at which the seal ring 20 transitions from the first stage to the second stage may be application specific, and may be in the range from 10 psi to 1 ,000 psi, by way of a non limiting example. For example, in a hydraulic application, the transition of the seal ring 20 from the first to second stage may occur when fluid pressure is in a range from 100 psi to 1,000 psi; whereas in a pneumatic application, the transition may occur in a range from 10psi to 100 psi. As shown in the illustrated embodiment, the first groove portion 52 may include the tapered surface 70 that tapers radially inwardly toward the second groove portion 54 to facilitate the transition of the seal ring 20 between stages.

As discussed above, the second groove portion 54 is configured to be a higher-compression stage than the first groove portion 52, such that the second groove portion 54 provides a compressive force to the seal ring 20 that is greater than a compressive force provided by the first groove portion 52. In this manner, when the seal ring 20 transitions to the second groove portion 52, the seal ring 20 is pushed radially inwardly with greater force against the radially outer sealing surface 49 of the conduit 14 to seal against the higher fluid pressures. To provide such sealing engagement at the higher fluid pressure levels (e.g., at the transitional fluid pressure level described above or greater), in exemplary embodiments the second groove portion 54 is configured to compress the seal ring 20 in a range from 15% to 30% (compressed size of seal ring 20 compared to uncompressed size in terms of change in cross-sectional radial width), such as 15%, 20%, 25%, 30%, etc., including all ranges and sub-ranges between the stated values, for example.

The two-stage seal groove 50 may have any suitable configuration for providing the desired compression of the seal ring 20 at both the first and second groove portions 52, 54. In the illustrated embodiment, for example, the first groove portion 52 has a first groove depth (in the radial direction) that is greater than a second groove depth (in the radial direction) of the second groove portion 54. These different groove depths cause the seal ring 20 to compress relative to its uncompressed state (as shown in Fig. 1 , for example) to thereby push the seal ring 20 radially inwardly against the outer surface of the conduit 14, as described above. In exemplary embodiments, the differences in volume of the respective groove portions 52, 54 relative to the uncompressed volume of the seal ring 20 may provide the desired amount of fill of the seal ring 20. For example, the first groove portion 52 may define a first groove volume that is in the range from 80% to 90% of the volume of the seal ring 20 in the uncompressed state; and the second groove portion may define a second groove volume that is in the range from 70% to 80% of the volume of the uncompressed seal ring 20. In exemplary embodiments, the seal ring 20 is expected to stay in the second groove portion 54 even when system fluid pressure drops below the pressure level that caused the seal ring 20 to transition to the second stage. As such, in the illustrated embodiment the first stage of the seal groove 50 primarily is used for initial assembly as described above, and the second stage is used thereafter during normal operation of the fluid system.

According to an aspect, a threaded coupling assembly for interconnecting a first fluid conduit with a second fluid conduit, the threaded coupling assembly including: a coupling nut rotatable about a longitudinal axis of the first fluid conduit and having a thread for threadably coupling the first fluid conduit to the second fluid conduit; a sealing sleeve having a radially inner surface for receiving a forward end portion of the first fluid conduit, and a two-stage circumferential seal groove in the radially inner surface of the sealing sleeve, the two-stage circumferential seal groove comprising a first groove portion and a second groove portion, wherein the first groove portion has a first groove depth that is greater than a second groove depth of the second groove portion; and a seal ring disposed in the two-stage circumferential seal groove for sealingly engaging a radially outer surface of the forward end portion of the first fluid conduit; wherein the threaded coupling assembly is configured such that: (i) when the forward end portion of the first fluid conduit is inserted into the sealing sleeve, the seal ring is disposed in the first groove portion; and (ii) when the threaded coupling assembly is in a fully-assembled and pressurized state above a specified fluid pressure level, the seal ring is transitioned to the second groove portion, whereby the seal ring is pushed radially inwardly against the radially outer surface of the fluid conduit to enhance sealing performance.

According to another aspect, a threaded coupling assembly for interconnecting a first fluid conduit with second fluid conduit, the threaded coupling assembly including: a holding ring having a cutting tooth portion, a first engaging surface, and a second engaging surface, wherein the cutting tooth portion is configured to cut into and hold a forward end portion of the fluid conduit; a coupling nut engageable with the first engaging surface of the holding ring; a sealing sleeve having a radially inner surface for receiving the forward end portion of the fluid conduit, a first engagement portion for engaging the second engaging surface of the holding ring, and a circumferential seal groove in the radially inner surface of the sealing sleeve, the circumferential seal groove comprising a first groove portion and a second groove portion, and a seal ring disposed in the circumferential seal groove for sealingly engaging a radially outer surface of the forward end portion of the fluid conduit; wherein the first groove portion is configured to contain the seal ring when the threaded coupling assembly is in a fully-assembled state, such that the seal ring provides a sealing engagement against a sealing surface of the forward end portion of the fluid conduit that is sufficient to seal at a first fluid pressure level; and wherein the second groove portion is configured to receive the seal ring from the first groove portion when the threaded coupling assembly is in the fully- assembled state and pressurized to a second fluid pressure level that is greater than the first fluid pressure level, the second groove portion being configured to increase compression of the seal ring relative to compression provided by the first groove portion such that the seal sleeve provides sufficient sealing at the second fluid pressure level.

Embodiments may include one or more features of the foregoing aspects, separately or in any combination, which may be combined with one or more of the following additional features, which may be included separately or in any combination.

In some embodiments, the first groove portion is configured to provide a first compressive force on the seal ring that: (i) enables a fluid seal at a first fluid pressure level that is below the specified pressure level, and (ii) enables the forward end portion of the fluid conduit to push past the seal ring without damage or displacement of the seal ring.

In some embodiments, the second groove portion is configured to provide a second compressive force on the seal ring that is greater than the first compressive force to fluidly seal at a second fluid pressure level that is at or above the specified fluid pressure level.

In some embodiments, the first groove portion is configured to compress the seal ring in a range from 8% to 15%.

In some embodiments, the second groove portion is configured to compress the seal ring in a range from 15% to 30%.

In some embodiments, the first groove portion includes a tapered surface that tapers radially inwardly toward the second groove portion to facilitate transition of the seal ring from the first groove portion to the second groove portion.

In some embodiments, a radially outer bottom surface of the circumferential seal groove is a continuously tapered surface between a forward end surface and a rearward end surface of the seal groove, the tapered surface forming respective radially outer portions of the first and second groove portions. In some embodiments, the seal groove has a forward face and a rearward face, the forward face forming an axial end surface of the first groove portion, and the rearward face forming an axial end portion of the second groove portion.

In some embodiments, the two-stage circumferential seal groove further includes a third groove portion between the first and second groove portions.

In some embodiments, a forward end portion of the sealing sleeve has a radially extending abutment for engaging an end face of the forward end portion of the fluid conduit when the fluid conduit is fully inserted into the sealing sleeve.

In some embodiments, a forward end of the sealing sleeve forms a first radially extending stop face which, when the threaded coupling assembly is in the fully-assembled state, abuts a radially extending face of the other fluid conduit.

In some embodiments, the coupling assembly further includes a holding ring that is configured to grip the first fluid conduit and cooperate with the coupling nut to apply axial force to the first fluid conduit.

In some embodiments, the holding ring includes a cutting tooth portion, a first engaging surface for engaging the coupling nut, and a second engaging surface for engaging the sealing sleeve, wherein the cutting tooth portion is configured to cut into and hold the forward end portion of the fluid conduit.

In some embodiments, threadable coupling of the first fluid conduit to the second fluid conduit via the coupling nut causes the coupling nut to apply force to the first engaging surface of the holding ring, thereby forcibly drawing the second engaging surface of the holding ring slidably against an engagement portion of the sealing sleeve which pushes the cutting tooth portion radially inwardly to cut into and hold the radially outer surface of the fluid conduit.

In some embodiments, after the cutting tooth portion has cut into and held the radially outer surface of the fluid conduit, further threadable coupling by the coupling nut forcibly draws the forward end portion of the first fluid conduit toward the second fluid conduit for effecting a sealing engagement between the first and second fluid conduits.

In some embodiments, the engagement portion of the sealing sleeve includes a conically progressing sliding surface that faces radially inwardly and rearwardly. In some embodiments, the first engaging surface of the holding ring is radially outward and opposite the cutting tooth portion.

In some embodiments, the holding ring includes a forwardly facing stop face, and wherein a rearward end portion of the sealing sleeve includes a radially extending stop face which, when the threaded coupling assembly is in the fully-assembled state, abuts the forwardly facing stop face of the holding ring and stops the sealing sleeve with respect thereto.

In some embodiments, the first engaging surface of the holding ring is a radially outwardly facing conical surface that is configured to engage a corresponding radially inwardly facing conical surface of the nut.

In some embodiments, the first engaging surface of the holding ring includes a notch that is configured to damp vibration transmission from a cutting tooth portion of the holding ring to the first conduit.

In some embodiments, the sealing sleeve, the holding ring, and the seal ring, prior to assembly, are operatively coupled together to form a single assembly unit.

In some embodiments, a combination of any of the foregoing is provided with the first fluid conduit and the second fluid conduit; wherein the second fluid conduit is a fitting, having a fluid passage, an external thread, an end face having a radial groove, and a seal disposed in the radial groove.

According to another aspect, a sealing sleeve for use in interconnecting fluid-carrying conduits includes: a radially inner surface for receiving a forward end portion of a fluid conduit; a circumferential seal groove in the radially inner surface of the sealing sleeve, the circumferential seal groove comprising a first groove portion and a second groove portion, wherein the first groove portion has a first groove depth that is greater than a second groove depth of the second groove portion; and a forward end portion having a radially inwardly extending abutment for engaging an end face of the forward end portion of the fluid conduit when the fluid conduit is inserted into the sealing sleeve.

According to another aspect, a combination includes: the sealing sleeve according to any of the foregoing; a seal ring disposed in the circumferential seal groove; and a holding ring having a cutting tooth portion, a first engaging surface for engaging a coupling nut, and a second engaging surface for engaging the sealing sleeve, wherein the cutting tooth portion is configured to cut into and hold the forward end portion of the fluid conduit; wherein the sealing sleeve, the seal ring, and the holding ring are operatively coupled together to provide a single assembly unit.

It is to be understood that terms such as “top,” “bottom,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “forward,” “rearward,” and the like as used herein may refer to an arbitrary frame of reference, rather than to the ordinary gravitational frame of reference.

As used herein, an “operative connection,” or a connection by which entities are “operatively connected,” is one in which the entities are connected in such a way that the entities may perform as intended. An operative connection may be a direct connection or an indirect connection in which an intermediate entity or entities cooperate or otherwise are part of the connection or are in between the operatively connected entities. An operative connection or coupling may include the entities being integral and unitary with each other.

The phrase “and/or” should be understood to mean “either or both” of the elements so conjoined, i.e. , elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a "means") used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e. , that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.