Improvements in or relating to threaded members

Abstract: The disclosure relates to a threaded member (21) having an annular groove (24) which is of greater depth than the base of the adjacent thread (22). A resilient ring (26) is mounted in the groove having an outer periphery (27) extending above the base of the thread. A plurality of projections (28) are formed at spaced locations around the ring to be deformed by the engagement of the threaded member with a coresponding threaded member to form a seal between the respective threads of the engaging members.

Description: This invention relates to threaded members and in particular to the sealing of threaded members. The invention is particularly applicable to threaded members on tube coupling bodies for providing a sealed connection of the bodies to further threaded components. EP-A-0459957 discloses a tubular connector having a cylindrical screw threaded shank for engagement in a correspondingly threaded hole in a body. An annular groove is formed part-way along the threaded shank and an annular seal is located in the groove to act between the threaded shank and the threaded bore in the body. Similar arrangements are disclosed in US-A-2086133 and FR-A-1571744. The invention provides a threaded member having an annular groove which is of greater depth than the base of the adjacent thread, a resilient ring mounted in the groove and having an outer periphery located above the base of the thread to be deformed by the engagement of the threaded member with a corresponding threaded member to form a seal between the respective threads of the engaging members, characterised in that the resilient ring has a plurality of projections formed at spaced locations around its outer periphery comprising ribs formed integrally with the resilient ring and extending parallel to the axis of the ring across the outer face of the ring periphery, the ribs being tapered in both width and height to a point towards the entry end of the threaded member. Preferably the annular groove is formed part-way along the threaded member with the thread extending on either side of the groove. It is further preferred that the outer periphery of the resilient ring lies just below the outer profile of the thread and the projections on the outer periphery extend above the profile of the thread. In any of the above arrangements the ribs may be triangular in cross-section through the axis of the ring. The base of the annular groove containing the resilient ring may be knurled to grip with the inner face of the ring. Also any of the above arrangements the threaded member may be of parallel or tapered form. Further, the threaded member may be a male member having an external thread and external annular groove in which the seal is located to engage in a corresponding internally threaded female member or may be a female member having an internal thread and internal annular groove in which the resilient seal is located to receive an externally threaded male member. The resilient ring may be formed from an elastomeric material and in the case where the invention is applied to an externally threaded male member is installed in the annular groove in the threaded member by stretching over the entry end of the threaded member to snap into the groove. In accordance with a further feature of the invention the base of the groove may be undercut in one or both corners of the groove to form an encircling recess or recesses to accommodate deformation of the resilient sealing ring when said threaded members are engaged. More specifically the base of the groove between the undercut corners thereof has axially extending splines and the inner periphery of the resilient ring is correspondingly splined to resist rotation of the ring with respect to the threaded member when the latter is engaged with the other threaded member. The splines may be of trapezoidal cross section. According to a still further feature of the invention the projections on the outer periphery of the ring may be tapered at both ends. The following is a description of some specific embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a general assembly view of a tube coupling having a sealed male form threaded connector; Figure 2 is a side view of the seal of the threaded connector of Figure 1; Figure 3 is an end view of the seal; Figures 4 and 5 illustrate the application of the invention to female form threaded members; Figure 6 is a scrap section through a part of an externally threaded member taken along the axis of the member; Figure 7 is a section on the line 7-7 on Figure 6; Figure 8 is an end view of a resilient ring for location on the threaded member; Figure 9 is a cross-sectional view on the line 9-9 on Figure 8; and Figure 10 is a view of the connector of Figure 1 screwed into a socket. Figure 1 of the drawings shows a tube coupling connector indicated generally at 10 comprising a body 11 machined from brass or stainless steel and having a throughway 12. One end 13 of the body is fitted with a moulded plastics insert sleeve 14 formed with an internal tapered cam surface 15 reducing towards the open end of the body. An annular collet 16 is located in the insert having resilient fingers 17 engaging the cam surface to receive a tube to be locked in the body by the collet. The throughway is reduced in diameter at a first step 18 where an O-ring seal 19 is located and a second step 20 with which the end of the tube to be located in the body engages. As indicated above, one end of the coupling body is adapted to receive a collet for connecting a tube in the coupling body. The other end of the coupling body indicated at 21 is a male form threaded member having an external parallel screw thread indicated at 22 and terminating in an end face 23. Part way along the screw thread, the coupling body is formed with a deep annular groove 24 the bottom of which lies below the bottom face of the thread indicated at 25. A resilient sealing ring 26 is disposed in the groove 24 formed from an elastomeric material such as a polyester. The outer periphery 27 of the resilient ring lies just below the outer periphery of the thread and is formed at spaced locations around the ring with four axially extending ribs 28 integral with the ring as best seen in Figures 2 and 3. The ribs are of generally triangular cross-section as seen in a plane containing the axis of the ring and taper both in width and height from one end 29 of the ring where they project above the adjacent thread periphery to a point 30 at the other end 31 of the ring. The ring is installed in the annular groove with the tapered ends of the ribs adjacent the entry end of the screw thread, that is the end adjacent end 23 of the coupling body. When the threaded end of the coupling body is screwed into a corresponding threaded socket in another component as shown in Figure 10, the ribs of the sealing ring are initially engaged and deformed by the socket thread which then bites into the outer periphery of the sealing ring itself to deform the ring to fill the gaps between the inner and threads. A seal is thereby created between the threads to prevent loss of fluid or air between the threads. The resilient sealing ring 26 is formed as an injection moulding and is stretched and drawn over the threaded end of the coupling body to snap into the annular groove whilst still warm from its moulding operation. The outer periphery of the end 32 of the threaded member is bevelled as indicated at 24 to facilitate drawing the ring onto the threaded member. The internal diameter of the resilient ring is such that the ring grips around the base of the groove and the base may be knurled to provide a surface roughness to grip with the ring and thereby prevent the ring turning when the tube coupling body is screwed into the outer threaded component. Conventionally, when a seal has to be provided between a threaded adapter and a component into which it is screwed, the bore in the component has to be enlarged to accommodate the seal and usually this entails enlarging the component itself. It will be appreciated that, with the above arrangement, because the seal is accommodated in the groove in the male adapter, no consequential increase in the size of the component in which the adapter is fitted is required. Reference is now made to Figure 4 of the drawings which illustrates the application of the invention to an internally threaded female member. The female member is in the form of a socket 40 having an open ended straight bore 41 formed with a parallel internal screw thread 42 to receive a threaded component to be secured in the bore. An annular groove 43 is formed around the open end of the bore to receive a resilient seal 44. The seal is held captive in the groove by an annular cover plate 45 secured to the end of the socket and overlying the adjacent end of the seal. The seal is formed from an elastomeric material as before and has integral upstanding axial extending ribs 46 around its inner periphery. As before, the ribs are of triangular cross-section tapering towards the open end of the bore. When a male screw component is inserted in the socket, the threads of the male component bite into the ribs 46 and the inner periphery of the seal and the resulting deformation of the material of the seal fully fills the thread at the male component to create a seal with the male component at the end of the socket. Figure 5 of the drawings shows a similar arrangement except that the groove 43 is formed part-way along the bore 41 spaced from the open end thereof. In this case of course the separate annular cover plate 45 is not required. Reference is now made to Figures 6 to 9 which illustrate a number of further modifications to the above constructions. Firstly, as shown in Figure 6, the groove 24 is undercut at its corners to form recesses 24a encircling the groove to accommodate excess material of the resilient ring when it is deformed into the groove by engagement of the threaded members as described above. The base of the groove 24 is formed with splines 24b extending parallel to the axis of the threaded member, the splines being of truncated triangular cross-section as best seen in Figure 7. The resilient ring 26 has an inner periphery formed with axially extending triangular-section grooves 50 to engage with the splines and prevent the ring rotating with respect to the threaded member when the threaded member is engaged in the corresponding other threaded component. As shown in Figures 8 and 9 of the drawings, the ribs 28 on the outer periphery of the ring 26 are straight-cut with chamfered ends 28a (see Figure 9) to allow the ring to be engaged from either end in the other threaded member.

Claims: A threaded member having an annular groove (24) which is of greater depth than the base of the adjacent thread (22), a resilient ring (26) mounted in the groove and having an outer periphery (27) located above the base of the thread to be deformed by the engagement of the threaded member with a corresponding threaded member to form a seal between the respective threads of the engaging members, characterised in that the resilient ring has a plurality of projections (28) formed at spaced locations around its outer periphery (27) comprising ribs formed integrally with the resilient ring and extending parallel to the axis of the ring across the outer face of the ring periphery, the ribs being tapered in both width and height to a point (30) towards the entry end (31) of the threaded member. A threaded member as claimed in Claim 1, characterised in that the annular groove (24) is formed part-way along the threaded member (21) with the thread (22) extending on either side of the groove. A threaded member as claimed in Claim 1 or Claim 2, the outer periphery of the resilient ring (27) lies just below the outer profile of the thread (22) and the projections (28) on the outer periphery extend above the profile of the thread. A threaded member as claimed in any of Claims 1 to 3, the ribs (28) are triangular in cross-section through the axis of the ring. A threaded member as claimed in any of the preceding claims, the base of the annular groove (26) containing the resilient ring is knurled to grip with the inner face of the ring. A threaded member as claimed in any of the preceding claims, the threaded member (21) is of parallel or tapered form. A threaded member as claimed in any of the preceding claims, the member (21) is a male member having an external thread (22) and external annular groove (24) in which the resilient ring (26) is located to engage in a corresponding internally threaded female member. A threaded member as claimed in any of claims 1 to 6, the threaded member (40) is a female member having an internal thread (42) and internal groove (43) in which the resilient ring (44) is located to receive an externally threaded male member. A threaded member as claimed in any of the preceding claims, the resilient ring (26,44) is formed from an elastomeric material and in the case where the threaded member is an externally threaded male member is installed in the annular groove in the threaded member by stretching over the entry end of the threaded member to snap into the groove. A threaded member as claimed in any of the preceding claims, the base of the groove (24) is undercut in one or both corners (24a) of the groove to form an encircling recess or recesses to accommodate deformation of the resilient sealing ring when said threaded members are engaged. A threaded member as claimed in Claim 10, the base of the groove (24) between the undercut corners thereof has axially extending splines (24b) and the inner periphery of the resilient ring (26) is correspondingly splined (50) to resist rotation of the ring with respect to the threaded member when the latter is engaged with the other threaded member. A threaded member as claimed in Claim 11, the splines (24b) are of trapezoidal cross section. A threaded member as claimed in any of the preceding claims, the projections (28) on the outer periphery of the ring (26) are tapered at both ends (28a).

Inventors: GUEST JOHN DEREK, GUEST, JOHN DEREK
Applicants: GUEST JOHN D, GUEST, JOHN DEREK
Application year: 1993
Main classification: F16L15
IPC codes: F16L15, F16B37, F16B39