GB2390882A

GB2390882A - A pipe coupling with expandable gripper ring

Info

Publication number: GB2390882A
Application number: GB0312724A
Authority: GB
Inventors: Sergio Marius Julius Meli
Original assignee: MELIMATIC Ltd
Current assignee: MELIMATIC Ltd
Priority date: 2002-06-28
Filing date: 2003-06-04
Publication date: 2004-01-21
Anticipated expiration: 2023-06-04
Also published as: GB0214971D0; GB2390882B; GB0312724D0

Abstract

A pipe coupling comprises a body member 10 having a socket portion 12 defining a bore 16 into which a pipe 18 may be inserted with a clearance, the inner end of the bore has a shoulder formation 20 for abutment of the end of a pipe 18, a frusto-conical groove 30 is provided in the internal diameter of the bore 16 adjacent its open end 26, the groove 30 decreasing in depth towards the open end 26 of the bore 18 and a resilient gripper ring 34 of frusto-conical configuration diverging towards the open end 26 of the bore 18 located in the groove 30. The gripper ring 34 has an external diameter greater than the internal diameter of the groove 30 at the outer end thereof and smaller than the internal diameter of the first groove 30 at the inner end thereof and is adapted to be expanded by insertion of a pipe 18 into the bore 16, so that the gripper ring 34 will resiliently engage the external diameter of the pipe 18. The gripper ring 34 being forced into securely into engagement with the pipe 18 by engagement of the base of the groove 30, when subjected to a load withdrawing the pipe 18 from the fitting. A second groove 24 is provided in the internal diameter of the bore 16, intermediate of the first groove 30 and the shoulder formation 20 and a sealing element 28 is located in the second groove 24, to provide a seal between the pipe 18 and fitting. The sealing element 28 may comprise a pair of O-rings 28 and a reinforcing tubular liner maybe inserted into the pipe 18 before it is inserted into the pipe fitting. A tool may be used to release the gripper ring 34 from the surface of the pipe.

Description

2sqo8s - 1 - PIPE FITTINGS

The present invention relates to pipe fittings.

Hitherto, pipe fittings used in the plumbing industry have been soldered to the pipes or have been compression fittings, comprising a pair of screw 5 threaded components which are screwed together to compress a ring which grips and provides a seal with the pipe. Such fittings take time to assemble and care and skill are required to ensure that a water-tight joint is formed.

According to one aspect of the present invention, a pipe fitting comprises 10 a body member having a socket portion, the socket portion defining a bore into which a pipe may be inserted with a clearance, the inner end of the bore having a shoulder formation for abutment of the end of a pipe, a first groove being provided in the internal diameter of the bore adjacent its open end, the first groove decreasing in depth towards the open end of 15 the bore, and a second groove being provided in the internal diameter of the bore, intermediate of the first groove and the shoulder formation, a sealing element being located in the second groove, the sealing element being adapted to sealingly engage a pipe inserted into the bore; and a resilient gripper ring located in said first groove, the gripper ring being of 20 frusto-conical configuration diverging towards the open end of the bore, the gripper ring being adapted to be expanded by insertion of a pipe into the bore, the external diameter of the gripper ring being greater than that of the first groove at the outer end thereof and smaller than that of the first groove at the inner end thereof.

25 With a pipe fitting of the present invention, the fitting may be assembled on the pipe merely by pushing the pipe into the bore of the socket portion.

The gripper ring is thereby expanded to grip the pipe and the sealing element produces a water-tight seal. If a load is applied to the pipe

- 2 pulling it out of the socket portion, the external diameter of the gripper ring will engage against the first groove, compressing the gripper ring onto the pipe and further increasing the clamping force on the pipe. This fitting will furthermore permit rotation of the fitting with respect to the pipe, for 5 example to allow the fitting to be screwed onto another component.

According to a preferred embodiment of the invention, the first groove defines radially extending wall formations at its axially inner and outer extremities. According to a further embodiment of the invention, a radial slot may be 10 provided in the socket portion of the fitting, the radial slot opening into the first groove, to provide axis to the gripper ring, by which the gripper ring may be released to permit removal of the pipe from the fitting.

According to a preferred embodiment of the invention the sealing element extends axially of the bore of the socket portion, in order to inhibit axial 15 misalignment of the pipe and pipe fitting and to maintain sealing engagement in case of such misalignment. Preferably two axially separated sealing elements may be used for this purpose.

The invention is now described, by way of example only, with reference to the accompanying drawings, in which: 20 Figure 1 shows a cross-sectional elevation of a pipe fitting in accordance with the present invention; Figure 2 shows a sectional view along the line II-II of Fig. 1; and Figure 3 shows a side elevation of a modified version of the pipe fitting shown in Fig. 1.

f - 3 The pipe fitting illustrated in Figure 1 comprises a body member 10 having a socket portion 12 at one end and a screw threaded portion 14 by which the fitting may be connected to a component, for example, a water meter, at the other end.

5 The socket portion 12 defines a bore 16 with an internal diameter sufficient to accommodate tolerance variations in the external diameter of i a pipe 18, for which the fitting is designed, so that irrespective of i tolerance variations in the size of the pipe 18, the pipe 18 may be inserted into the bore 16 with a clearance.

10 A shoulder formation 20 is provided at the inner end of the bore 16, between the socket portion 12 and screw threaded portion 14. The shoulder formation 20 provides an abutment for the end of the pipe 18, when the fitting is secured to the pipe 18.

A pair of annular grooves 24 are provided in the internal diameter of the 15 bore 16 intermediate of the open end 26 thereof and the shoulder formation 20. A pair of elastomeric O rings 28 are located in the grooves 24, the internal diameters of the 0 rings 28 being less than the minimum tolerance variation of the external diameter of the pipe 18, so that upon insertion of the pipe 18 into the bore 16, the 0 rings 28 will be 20 compressed into the grooves 24 and will provide a water-tight seal with the pipe 18.

A groove 30 is provided adjacent the open end 26 of the bore 16, the groove 30 being defined by axially inner and outer wall formations 32,34 and having a frusto-conical circumferential surface, so that the depth of 25 the groove 30 increases from the free end 26 of the bore 16.

A split frusto-conical gripper ring 34 is located in the groove 30, the

( - 4 diameter of the gripper ring increasing towards the open end of the bore 16. The gripper ring 34 is in the form of a frusto-conical washer with a gap 36 in its periphery. The internal diameter of the gripper ring 34 is dimensioned so as to resiliently engage the external diameter of a pipe 18 5 of minimum tolerance variation whilst maintaining a clearance between the ends defining the gap 36. The external diameter of the gripper ring 34 is dimensioned so that it is less than the maximum diameter of the frusto-conical groove 30 when expanded by engagement of a pipe 18 with external diameter of maximum tolerance variation and is larger than 10 the smaller diameter end of the groove 30 when engaged on a pipe with an external diameter of minimum tolerance variation.

To connect the fitting to a length of pipe, the pipe is merely inserted into the bore 16, thereby expanding the gripper ring 34 and sealingly engaging the O rings 28. If a force is applied to the pipe 18, to withdraw it from 15 the fitting, the gripper ring 34 moves outwardly until its external diameter engages the conical surface of groove 30. Further loading of the pipe away from the end fitting then compresses the gripper ring 34 harder onto the pipe 18, thereby increasing the clamping force.

Compression of the spaced sealing rings 28 by the pipe 18 will restrain 20 the pipe 18 co-axially of the fitting 10 and even if there is slight misalignment of the pipe 18 and fitting, will maintain sealing engagement with the pipe 18.

As illustrated in Figure 3, a slot 40 may be provided in the socket portion 12 of the fitting 10, the slot 40 extending angularly about part of the 25 socket portion 12 and opening to the frusto-conical groove 30. An end of the gripper ring 34 may then be engaged through the slot 40 with a suitable tool, and the gripper ring 34 withdrawn through the slot 40, in order to release the pipe from the fitting.

- 5 The body member 10 of the pipe fitting disclosed above may be made of any suitable material, but will normally be made of corrosion resistant materials such as brass, stainless steel or plastics material. The gripper ring 34 will normally be formed of copper or stainless steel, although a 5 suitable resilient plastics material may be used. The fitting may be used with metal or plastics pipe 18. With flexible pipes, a rigid sleeve may be inserted into the end of the tube, before the fitting is attached. With plastic or soft metal pipes, the gripper ring 34 may cut into the wall of the pipe, particularly when a tensile load is applied pulling the pipe 18 out of 10 the fitting. The degree to which the gripper ring 34 will cut into the wall of the pipe may be controlled by appropriate dimensioning of the gap 36 in the gripper ring 34.

Various modifications may be made without departing from the invention.

For example, while the fitting described above has a screw threaded 15 portion for attachment of the pipe to another component, the fitting may alternatively be formed integrally if the component, for example a water tap or valve, or the fitting may be coupling with two or more socket sections to connect two or more lengths of pipe.

For use with thin walled pipes or pipes made of plastic materials, a tubular 20 reinforcing liner may be inserted into the bore of the tube, before the pipe is inserted into the pipe fitting.

While the pipe fittings in accordance with the present invention are particularly suitable for the plumbing industry, the may be used for other applications, for example the gas and chemical engineering industries, in 25 hydraulic systems and tubular conduits for electrical cables.

Claims

- 6 Claims.

1. A pipe fitting comprising a body member having a socket portion, the socket portion defining a bore into which a pipe may be inserted with a clearance, the inner end of the bore having a shoulder formation for 5 abutment of the end of a pipe, a first groove being provided in the internal diameter of the bore adjacent its open end, the first groove decreasing in depth towards the open end of the bore, and a second groove being provided in the internal diameter of the bore, intermediate of the first groove and the shoulder formation, a sealing element being located in the 10 second groove, the sealing element being adapted to sealingly engage a pipe inserted into the bore; and a resilient gripper ring located in said first groove, the gripper ring being of frusto-conical configuration diverging towards the open end of the bore, the gripper ring being adapted to be expanded by insertion of a pipe into the bore, the external diameter of the 15 gripper ring being greater than that of the first groove at the outer end thereof and smaller than that of the first groove at the inner end thereof.

2. A pipe fitting according to claim 1 in which the gripper ring is a frusto-conical washer with a gap in its periphery.

3. A pipe fitting according to claim 2 in which the gap is dimensioned 20 such that when the gap is closed, the internal diameter of the gripper ring will be a predetermined amount less than the minimum tolerance external diameter of the pipe size of which the fitting is designed.

4. A pipe fitting according to claim 1 in which the first groove has radially extending axially inner and outer walls.

26 5. A pipe fitting according to any one of claims 1 to 4 in which the first groove is defined by a frusto-conical circumferential surface.

- 7 6. A pipe fitting according to any one of claims 1 to 5 in which the sealing element extends axially of the bore of the socket portion.

7. A pipe fitting according to claim 6 in which the sealing element comprises a pair of resilient O-rings located in axially spaced annular 5 grooves in the internal diameter of the bore of the socket portion.

8. A pipe fitting according to any one of the preceding claims in which a circumferential slot is provided in the wall of the socket portion, the slot opening to the first groove, to provide access for removal of the gripper ring from the first groove, when the fitting is assembled on a pipe.

10 9 A pipe fitting according to any one of the preceding claims in which a reinforcing tubular liner is inserted into the bore of the pipe, before the pipe is inserted into the pipe fitting.

10. A pipe fitting substantially as described herein, with reference to and as shown in figures 1 and 2, and figure 3 of the accompanying 1 5 drawings.