GB2143918A

GB2143918A - Pipe couplings

Info

Publication number: GB2143918A
Application number: GB08418697A
Authority: GB
Inventors: David Robert Elliott
Original assignee: Hepworth Plastics Ltd
Current assignee: Hepworth Plastics Ltd
Priority date: 1983-07-23
Filing date: 1984-07-23
Publication date: 1985-02-20
Also published as: GB8418697D0; GB2143918B

Abstract

A pipe coupling (1) has a pair of sockets having first socket portions (2) separated by a rib (3) each side of which forms a shoulder serving as a stop for an inserted pipe (4), each first socket portion (2) opening into a second socket portion having a larger internal diameter. An end cap (6) having a cylindrical skirt portion (7) fits closely over the outside of the socket portion (5) and inwardly projecting means (8) on the skirt portion engages with detent means (9) on the outside of socket. A flange, integral with the skirt portion has a second flange portion (12) of frustoconical section extending inwardly to a terminal edge (13) of lesser diameter than the outside of the inserted pipe (4) so as to penetrate and secure the pipe against withdrawal from the socket. An elastomeric sealing ring (14) has a sealing portion (15) within the second socket portion integral with securing portion (16) housed within the space between the first flange portion (10) and the mouth of the socket. <IMAGE>

Description

SPECIFICATION Pipe couplings This invention relates to pipe couplings of the type in which an inserted pipe is sealingly engaged, by meansSof an elastomeric sealing ring, and retained, by means of a pipe retaining component, in a pipe socket, without the need for further adjustment.

A first known pipe coupling of this type comprises at least one plastics pipe socket having a first socket portion for receiving an end portion of a pipe as a close sliding fit and a second socket portion with a larger internal diameter towards the mouth of the socket, a plastics end cap screw-threadedly secured to the outside of the socket and having a radially inwardly projecting portion adjacent the mouth of the socket with an internal diameter not less than the internal diameter of the first socket portion, a stainless steel toggle ring housed in the second socket portion adjacent a shoulder between the first socket portion and the second socket portion, the toggle ring having a frusto-conical portion extending axially and radially inwardly to terminal edges at a lesser diameter than the outside of an inserted pipe so as to penetrate into and secure an inserted pipe against withdrawal from the coupling; a resilient sealing ring housed between the toggle ring and the inwardly projecting portion of the end cap, and a separating washer between the toggle ring and the sealing ring to prevent the sealing ring being damaged by the toggle ring on pipe insertion and in use.

This first known pipe coupling has the disadvantage that it comprises a large number of component parts which makes it expensive to manufacture and also makes automated assembly of the pipe coupling difficult and expensive.

It is an additional disadvantage of the manufacture of the pipe coupling in plastics that this results in a relatively large overall diameter which may cause problems in mounting the pipe coupling.

A second known pipe coupling of the type initially described comprises at least one pipe socket having a first socket portion for receiving an end portion of a pipe and a second socket portion with a larger internal diameter towards the mouth of the socket, an O-ring seal housed in the second socket portion and an end cap screw threadedly secured to the outside of the socket, the end cap having a radially inwardly projecting portion extending inwardly to terminal edges at a lesser diameter than the outside of an inserted pipe so as to penetrate into and secure an inserted pipe against withdrawal from the coupling.

This second known pipe coupling has the disadvantage that the pipe retaining component and hence the inserted pipe cannot be rotated relatively to the coupling, which causes problems in mounting the pipe coupling when it is part of a tee or elbow. A further disadvantage is that unless the pipe is exactly aligned with the axis of the coupling prior to insertion, the edges of the radially extending portion may be unequally distorted leading to failure to retain the pipe on pressurstation. Yet a further disadvantage is that on pressurisation the O-ring seal may be forced away from the pipe surface leading to ieak- age.

The principal object of the invention is to provide a pipe coupling of the type initially described which minimises the number of components parts and simplifies its assembly.

Further advantages of the invention will emerge in the course of the following description.

According to the present invention, a pipe coupling comprises at least one plastics socket having a first socket portion for receiving a pipe end as a close sliding fit and a second socket portion with a larger internal diameter towards the mouth of the socket; an end cap with a cylindrical skirt portion fitting closely over the outside of the socket, there being inwardly projecting means on the skirt portion for engagement with detent means on the outside of the socket when the cap is pushed onto the socket, and a flange integral with the skirt portion, the flange comprising a first flange portion directed radially inwardly so as to define a space between the first flange portion and the mouth of the socket, and a second flange portion of frusto-conical section extending inwardly to an aperture defining a terminal edge within the second socket portion and at a lesser diameter than the outside of an inserted pipe so as to penetrate and secure the pipe against withdrawal from the socket; and an elastomeric sealing ring having a sealing portion within the second socket portion integral with a securing portion housed within the space between the first flange portion and the mouth of the socket.

Thus the coupling consists of only three parts namely the socket, the sealing ring and the combined cap and retaining means, and assembly can be a simple matter of locating the sealing ring in the cap and pushing the assembled cap and sealing ring onto the socket until the inwardly projecting means on the skirt portion can engage with the detent means on the outside of the socket. To aid assembly of the cap onto the socket the outside of the mouth of the socket may be chamfered. This chamfer also then defines part of the space in which the securing portion of the sealing ring is housed.Alternalively the sealing ring can be initially located with its sealing portion inside the socket and with its securing portion abutting the mouth of the socket, and the cap then pushed over the sealing ring and socket until the inwardly projecting means on the skirt portion can engage with the detent means on the outside of the socket. For this method of assembly it is preferable to provide a chamfer on the outside of the securing portion of the sealing ring.

The combined cap and pipe retaining means is preferably of metal, and most preferably of stainless steel typically 0.2 to 0.3 mm in thickness. The overall diameter of the coupling is the outside diameter of the socket plus twice the thickness of the skirt of the cap, and the outside diameter of the socket can be such that the thickness round the second socket portion is comparatively small because the skirt portion of the metal cap round it prevents radial expansion of the plastics under pressure exerted by the sealing ring when a pipe end portion is inserted or when the coupling is pressurised. The overall diameter of the coupling is thus substantially less than known pipe couplings of the type initially described.

The angle of the inwardly directed frustoconical second portion of the flange of the cap is preferably between 30 and 45 relative to the axis of the socket and most preferably around 38 . The frusto-conical second flange portion is preferably provided with slits or notches extending from its aperture to enable it to open to facilitate insertion of a pipe end.

The teeth portions thus formed may be pressed to a V-section extending from their terminal edges, thereby forming points on their edges initially engaging an inserted pipe and affording greater resistance to flexing of the teeth Portions and therefore to pulling of the edges out of the inserted pipe. Alternatively the teeth portions may be flat at their terminal edges so as to minimise damage to the surface of the pipe in contact with the sealing portion of the sealing ring.

The detent means is preferably a circumferential shoulder on the outside of the socket or one side of a groove round the socket, preferably axially inwardly of the second socket portion so as to maximise the socket thickness at the detent position. The inwardly projecting means on the skirt portion of the cap may be formed by dimples or preferably by tabs defined by U-shaped slits and bent inwardly before or after fitting the cap on the socket.

Alternatively the inwardly projecting means may be a continuous (or discontinuous) rim rolled over inwardly at the end of the skirt portion remote from the flange before or after fitting. Preformed dimples, tabs or rolled-over rims can take advantage of the fact that resilience of the plastics socket (plus a little resilience in a rolled over rim or even more resilience in tabs) allows of snap fitting of the cap on the socket. When the inwardly projecting means are engaged with the detent means, the cap, and hence an inserted pipe, can be rotated relative to the socket which is advantageous in mounting the coupling especially when it is part of an elbow or a tee.

The sealing portion of the sealing ring (which sealing portion forms a seal between the inserted pipe and the second socket portion) may be substantially circular in crosssection, except where it merges into a neck portion integrating it with the securing portion; but the sealing portion is preferably generally triangular in axial cross-section with one corner merging into a neck portion integrating it with the securing portion so that the neck portion substantially fills the space between the frusto-conical portion of the flange of the cap and the inner surface of the second socket portion. This minimises the risk that the teeth portions will be unequally distorted on pipe insertion and when the pipe or coupling is subjected to a bending moment during use, and also prevents the sealing portion being forced away from the surface of the pipe when the coupling is pressurised.Sealing lips or ribs may be provided on the sealing surfaces of the sealing portion of the sealing ring.

The securing portion of the sealing ring preferably has an axial cross-section greater than the gap between the axially outermost end of the mouth of the socket and the first flange portion of the cap, to ensure the sealing ring is firmly held.

A slight lead-in taper may be provided between the first socket portion and the second socket portion.

An inwardly directed shoulder is preferably provided at the end of the first socket portion remote from the second socket portion to serve as a stop for an inserted pipe end, which shoulder may be the end of the bore of a pipe integral with the socket. Alternatively the socket may be one end of a coupling sleeve, bend or elbow, the other end of which has a simlar socket with sealing ring and combined cap and pipe retaining means; or it may be on one branch of a junction fitting (e.g. a tee) having a similar socket with sealing ring and combined cap and pipe retaining means on each of its other branches, or it may be integral with a connector for a tank or a tap.

An embodiment of the invention and modifications thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded part-sectional elevation of the basic component parts of an embodiment of the invention; Figure 2 is an elevation showing the parts of Fig. 1 assembled to form a coupling; Figure 3 is a longitudinal section of the coupling of Fig. 2 with both ends complete and a pipe inserted into one end; Figure 4 corresponds to Fig. 3 but shows a modification, Figure 5 is a fragmentary section of the coupling showing another modification; and Figures 6 to 10 are fragmentary sections of the coupling showing further modifications.

In Figs. 1 to 3 a pipe coupling sleeve 1 has a pair of sockets having first socket portions 2 separated by an inwardly directed rib 3 each side of which forms a shoulder serving as a stop for an inserted pipe 4, each first socket portion opening into a second socket portion 5 having a larger internal diameter, and is provided with an end cap 6 at each end, which end cap has a cylindrical skirt portion 7 fitting closely over the outside of the socket portion 5, and inwardly projecting means 8 (formed by tabs 8A defined by U-shaped slits 8B in the skirt portion 7) for engagement with detent means 9 (in the form of one side of a groove on the outside of the socket 5) when the cap 6 is pushed onto the socket.A flange, integral with the skirt portion 7, has a first flange portion 10 directed radially inwardly so as to define a space between the first flange portion 10 and the mouth 11 of the socket (which mouth is chamfered on the outside), and a second flange portion 12 of frustoconical section extending inwardly to a terminal edge 13 within the second socket portion 5 and at a lesser diameter than the outside of the inserted pipe 4 so as to penetrate and secure the pipe against withdrawal from the socket.An elastomeric sealing ring 14 has a sealing portion 15 within the second socket portion 5 integral with a securing portion 16 housed within the space between the first flange portion 10 and the mouth 11 of the socket, the securing portion 16 having an axial cross-section greater than the gap between the first flange portion 10 and the axially outermost end of the mouth of the socket, to ensure that the sealing ring is firmly held.

A lead in taper 17 is provided between each first socket portion 2 and its respective second socket portion 5.

In Fig. 4 the second flange portion 12 is provided with slits or notches 18 defining teeth portions 19 (with terminal edges 1 3A) which as shown in Fig. 5 may be pressed to a V-section extending from the terminal edge 1 3A, thereby forming points on their terminal edges initially engaging the inserted pipe 4 and affording greater resistance to flexing of the teeth portions 19 and therefore to pulling of the edges out of the inserted pipe.

In Fig. 6 the inwardly projecting means is a continuous rim 20 rolled over inwardly at the end of the skirt portion 7. Alternatively, as shown in Fig. 7, a rim 20A may be formed by bending the end of the skirt portion 7 inwardly through 90 or through 1 35' as with the rim 20B shown in Fig. 8 and may, in ech case, be continuous, or discontinuous, i.e., formed as castellations.

In Fig. 9 the sealing portion 1 6A of the sealing ring 14 is provided with lips 21 or alternatively as shown in Fig. 10 a series of ribs 22.

Claims

1. A pipe coupling comprising at least one plastics socket having a first socket portion for receiving a pipe end as a close sliding fit and a second socket portion with a larger internal diameter towards the mouth of the socket; an end cap with a cylindrical skirt portion fitting closely over the outside of the socket, there being inwardly projecting means on the skirt portion for engagement with detent means on the outside of the socket when the cap is pushed onto the socket, and a flange integral with the skirt portion, the flange comprising a first flange portion directed radially inwardly so as to define a space between the first flange portion and the mouth of the socket, and a second flange portion of frusto-conical section extending inwardly to an aperture defining a terminal edge within the second socket portion and at a lesser diameter than the outside of an inserted pipe so as to penetrate and secure the pipe against withdrawal from the socket; and an elastomeric sealing ring having a sealing portion within the second socket portion integral with a securing portion housed within the space between the first flange portion and the mouth of the socket.

2. A pipe coupling as in Claim 1, wherein the outside of the mouth of the socket is chamfered.

3. A pipe coupling as in Claim 1, wherein a chamfer is provided on the outside of the securing portion of the sealing ring.

4. A pipe coupling as in any one of Claims 1 to 3, wherein the end cap is made of metal.

5. A pipe coupling as in Claim 4, wherein the end cap is made of stainless steel of 0.2 to 0.3 mm thickness.

6. A pipe coupling as in any one of Claims 1 to 5, wherein the angle of the inwardly directed frusto-conical second portion of the flange of the cap is between 30 and 45' relative to the axis of the socket.

7. A pipe coupling as in Claim 6, wherein the said angle is 38 .

8. A pipe coupling as in any one of Claims 1 to 7, wherein the frusto-conical second flange portion is provided with slits or notches extending from its aperture to enable it to open to facilitate insertion of a pipe end.

9. A pipe coupling as in Claim 8, wherein teeth portions formed by the terminal edge between the slits or notches are pressed to a V-section extending from their terminal edges, thereby forming points on their edges initially engaging an inserted pipe and affording greater resistance to flexing of the teeth portions and therefore to pulling of the edges out of the inserted pipe.

10. A pipe coupling as in Claim 8, wherein teeth portions formed by the terminal edge between the slits or notches are flat at their terminal edges so as to minimise damage to the surface of the pipe in contact with the sealing portion of the sealing ring.

11. A pipe coupling as in any one of Claims 1 to 10, wherein the detent means is a circumferential shoulder on the outside of the socket or one side of a groove round the socket.

12. A pipe coupling as in Claim 11, wherein the shoulder or groove is disposed axially inwardly of the second socket portion so as to maximise the socket thickness at the detent portion.

13. A pipe coupling as in any one of Claims 1 to 12, wherein the inwardly projecting means on the skirt portion of the cap is formed by dimples.

14. A pipe coupling as in any one of Claims 1 to 12, wherein the inwardly projecting means on the skirt portion of the cap is formed by tabs defined by U-shaped slits and bent inwardly before or after fitting the cap on the socket.

15. A pipe coupling as in any one of Claims 1 to 12, wherein the inwardly projecting means on the skirt portion of the cap is formed as a continuous or discontinuous rim rolled over inwardly at the end of the skirt portion remote from the flange before or after fitting.

16. A pipe coupling as in any one of Claims 1 to 15, wherein the sealing portion of the sealing ring is substantially circular in cross-section, except where it merges into a neck portion integrating it with the securing portion.

17. A pipe coupling as in as in any one of Claims 1 to 15, wherein the sealing portion of the sealing ring is generally triangular in axial cross-section with one corner merging into a neck portion integrating itwith the securing portion so that the neck portion substantially fills the space between the frusto-conical portion of the flange of the cap and the inner surface of the second socket portion.

1 8. A pipe coupling as in Claim 17, wherein sealing lips or ribs are provided on the sealing surfaces of the sealing portion of the sealing ring.

19. A wipe coupling as in any one of Claims 1 to 18, wherein the securing portion of the sealing ring has an axial cross-section greater than the gap between the axially outermost end of the mouth of the socket and the first flange portion of the cap, to ensure the sealing ring is firmly held.

20. A pipe coupling as in any one of Claims 1 to 19. wherein a slight lead-in taper is provided between the first socket portion and the second socket portion.

21. A pipe coupling as in any one of Claims 1 to 20, wherein an inwardly directed shoulder is provided at the end of the first socket portion remote from the second socket portion to serve as a stop for an inserted pipe end.

22. A pipe coupling as in Claim 21, wherein the shoulder is at the end of the bore of a pipe integral with the socket.

23. A pipe coupling as in any one of Claims 1 to 20, wherein the socket is one end of a coupling sleeve, bend or elbow, the other end of which has a similar socket with sealing ring and end cap.

24. A pipe coupling as in any one of Claims 1 to 20, wherein the socket is on one branch of a junction fitting having a similar socket with sealing ring and end cap on each of its other branches.

25. A pipe coupling as in any one of Claims 1 to 20, wherein the socket is integral with a connector for a tank or a tap.

26. A pipe coupling substantially as herein before described with reference to Figs. 1 to 3 of the accompanying drawings or as modified as in any one or more of Figs. 4 to 10 of the accompanying drawings.