GB2182743A - Improvements in or relating to pipe couplings and parts therefor - Google Patents

Abstract

A pipe coupling comprising a sleeve-like body portion formed with at least one open end; an annular grip member located within the sleeve member against an internal radial shoulder thereof, the grip member being so formed as to have a cylindrical outer wall located closely adjacent the internal wall of the annular sleeve member and having teeth extending from the outer cylindrical wall radially and axially inwardly of the coupling; said teeth being of such a length as to bite into the external periphery of a pipe to be connected with the couplings to inhibit removal thereof, and the grip member being so disposed and located within the sleeve as to constitute a pipe registry for locating the end of the pipe radially within the sleeve; an elastomeric annular sealing member disposed within the sleeve axially outwardly of the grip member; and means for locating the sealing member within the sleeve. <IMAGE>

Description

SPECIFICATION Improvements in or relating to pipe couplings and parts therefor This invention relates to pipe couplings and parts therefor and more particularly the invention relates to such couplings (and their parts) for connecting pipes of plastics or soft metal.

It is to be understood that by the word "pipe" as used herein is included any pipe-like member such as pipe, tube and hose and hollow pipe fittings used in pipework such as elbows, "T" junctions, end members and valves for example. Similarly, the expression "pipe couplings" includes hollow pipe fittings such as elbows and "T" junctions when adapted to serve as couplings.

It is also to be understood that by the expression "soft metal" as used herein is meant that class of easily workable metals and metal alloys of which copper is a prime and typical example.

Couplings for such pipes have previously been proposed comprising a sleeve-like body portion adapted to encircle the two ends of juxtaposed pipes to be connected, the sleeve containing annular grip members, usually of spring metal having radially and axially inwardly extending teeth arranged to bite into the external periphery of the pipes to be coupled and inhibit removal once inserted into the sleeve-like portion, and annular sealing gaskets for providing a seal against the pipes to be connected. Usually the sleeve is provided with internal means constituting a pipe registry which locates the end of each pipe radially within the sleeve, and sometimes also locates each pipe axially within the sleeve.

It is an object of the present invention to enable the provision of couplings of this kind of compact configuration and effective assembly and operation.

According to one aspect of the present invention there is provided a pipe coupling comprising a sleeve like body portion formed with at least one open end; an annular grip member located within the sleeve member against an internal radial shoulder thereof, the grip member being so formed as to have a cylindrical outer wall located closely adjacent the internal wall of the annular sleeve member and having teeth extending from the outer cylindrical wall radially and axially inwardly of the coupling; said teeth being qf such a length as to bite into the external periphery of a pipe to be connected with the couplings to inhibit removal thereof, and the grip member being so disposed and located within the sleeve as to constitute a pipe registry for locating the end of the pipe radially within the sleeve; an elastomeric annular sealing member disposed within the sleeve axially outwardly of the grip member; and means for locating the sealing member within the sleeve.

The grip member may abut, at its axially inner end, against an internal annular shoulder around the inner walls of the sleeve.

The grip member may be provided with at least one radially inwardly extending projection from the axially inner end thereof which extends radially inwardly of the outside diameter of pipe to be connected so as to constitute an end stop or locator for the pipe within the sleeve.

Similarly the grip member may be provided with at least one radially inwardly extending projection from the axially outer end thereof which extends radially inwardly a lesser distance than the outside diameter of the pipe to be connected, so as to assist in the radial location thereof within the sleeve and, in one embodiment, to provide an axial stop for the sealing member.

The grip member may be cut from strip material and then shaped into its generally cylindrical configuration.

In accordance with another aspect of the invention there is provided a grip member for a pipe coupling comprising a strip of material bent into a cylindrical form having a plurality of teeth, cut from the cylindrical wall thereof, spaced therearound and projecting inwardly of the cylinder at an inclination to the axis thereof; and projections from the two ends of the cylinder extending radially inwardly to define openings of reduced diameter compared to that of the diameter of the cylinder. The inward projections at the two ends of the cylinder may define openings of different magnitudes.

By means of the invention we have enabled the provision of a coupling arrangement wherein the grip member serves as a pipe register to locate the axially inner end of the pipe to be connected. By this means the axial dimensions of the coupling can be considerably reduced.

The grip member may be formed of any appropriate material such as a spring metal e.g. spring steel.

The teeth may be bent radially and axially inwardly from strips extending axially inwardly of the body of the grip member compared to being bent from strips extending axially outwardly as with previously proposed grip members. Because of the consequent absence of a large angled bend at the root of the teeth of of finite radius, the grip member, and hence the coupling can be of a more compact radial configuration than hitherto.

The cylindrical body of the grip member may be provided with two or more rows of inwardly directed teeth spaced along the member. Teeth in different rows may be of different length and at different angles of inclination, whereby pipes of varying diameter and material can be satisfactorily accommodated.

It is to be noted that, because in use the grip member has a cylindrical body closely ad jacent the internal wall of the sleeve, much of its strength and support in operation is provided by the sleeve.

The means for locating the sealing member within the sleeve may be of any appropriate and desired form. Thus in one embodiment it may constitute an annular end insert member capable of insertion into the open end of the sleeve so as to locate and provide a compressive force upon the sealing member disposed therewithin to aid sealing of the coupling about a pipe.

With such an arrangement the coupling is fitted around the pipe to be connected, and the end insert member then inserted into the open end of the coupling about the pipe so as to compress the sealing member and provide the necessary seal with the pipe.

The end insert member may be removable so that the compression upon the sealing gasket can be relaxed so as to aid dismantling of the joint formed with the pipe by reducing the force necessary to remove the pipe from the coupling.

The coupling is preferably double-ended and has the same provision of grip member and sealing member at both ends. The internal annular shoulder may be located generally centrally of such a coupling to locate the ends of pipes inserted therein.

The annular insert may be a screw or may be a push-in or snap-in member formed for example of plastics material.

The side walls of the sleeve may taper away from the open end thereof or have a step reduction in diameter so as to assist the compression of the sealing member as the insert member is placed in position, and so as to ease the total assembly, and in particular to enable the user to "feel" that the pipe has been properly engaged in the grip member without obstruction of the "0" ring.

The invention includes within its scope a pipe joint incorporating a coupling as herein described.

In order that the invention may be more readily understood, one embodiment thereof will now be described by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic sectional elevation of part of a coupling and joint in accordance with the invention; Figure 2 is an enlarged sectional elevation of part of the grip member of the coupling of Figure 1; Figure 3 is an end elevation of the grip member of Figure 2; and Figure 4 is a developed plan view of the grip member of Figure 2.

Referring now to the drawings it will be seen that the coupling 1 (approximately half of the axial extent of which is shown) comprises a sleeve-like member 2 formed of copper having midway along its length an internal annular shoulder 3 and having adjacent each end an expanded diameter portion 4 terminating in a radially turned in lip 5.

Disposed within the sleeve-like member 2 and abutting the annular shoulder 3 is a spring steel grip member 6. The grip member 6 has a cylindrical portion 9 and is provided around its periphery with two rows of teeth 7, 8 cut from the cylinder and inclined radially and axially inwardly thereof. The grip member is provided at each end with a plurality of radially inwardly extending projections 10, 11, the projections 10 at the axially innermost end of the cylinder being of a greater length so as to provide an end stop abutting against the axial end 12 of a pipe 13 to be connected with the coupling, and the projections 11 at the axially outer end of the cylinder being of a shorter length so as to locate upon the external periphery of the pipe when disposed therein.

Abutting against the axially outer projections 11 of the grip member is an elastomeric "C" ring 14 formed for example of rubber and serving as a seal for the coupling. The "C" ring is held in place by means of a plastics screw-in annular end stop 15 engaging in the radially inwardly turned lip 5 of the end of the sleeve member. It is to be noted that the end stop engages with the "C" ring when it is in its axially outer disposition (as shown in the lower part of Figure 1) and upon screwing the end stop 15 into the coupling, the "0" ring is moved axially inwardly of the coupling so as to be compressed between the sleeve 2 and the pipe 13 to be connected with the coupling. In practice a compression of the order 25% is appropriate for sealing purposes.By way of example a coupling of the kind illustrated may be of a total of some 50mm in length and 22mm in mean diamter and may be arranged to accommodate and connect pipes of plastics or copper of the order of 15mm in outside diameter. In this case the "0" ring will reduce in radial thickness from approximately 3mm to approximately 2.25mm when undergoing pressure.

The end of the pipe 13 is provided with an internal supporting ferrule 16.

As can most clearly be seen from Figure 1, the grip member 6 acts as a radial and axial register for the pipe 13 within -the coupling, thereby significantly reducing the overall axial magnitude of the coupling.

Reference to Figure 4 illustrates the grip member 6 in its blank form. Thus it will be seen that the grip member comprises a strip of spring steel 17 cut so as to provide the radially inwardly extending projections 10, 11 at each axial end, and the radially and axially inwardly extending teeth 7, 8 in two rows (shown most clearly on the right hand side).

As will be appreciated the strip shown in Figure 4 is subsequently shaped so as to conform to the configuration illustrated in Figures 2 and 3 for use.

It will be seen therefore from Figures 3 and 4 that the grip member is not in the form of a continuous closed ring and is openable at the axial joint 18. This is possible because the grip member in operation, acquires its effectiveness and ability to locate the pipes and inhibit withdrawal through its teeth by its support from the sleeve-like member. One advantage of being able to manufacture the grip member from a continuous strip is that the cutting edges of the teeth can be greatly increased in length compared with conventional grip members.Hence not only will the teeth be capable of accommodating a wider range of pipe diameter tolerances, but also the intensity of pressure per mm of tooth contact will be reduced for the same pull-out strength requirement, having clear benefits from the point of view of life of the coupling, particularly when used in conjunction with plastics pipes.

Although the embodiment of the invention illustrated utilises inner and outer edges of the grip member cut and formed to the configuration generally of annular discs which abut both central internal shoulder of the fitting and the "0" ring, it will be appreciated that these abutment members can similarly be provided by other components such as washers to achieve the same effect.

In order for the teeth to be pressed easily from a flat strip it is necessary for the "knuckle line" at the root of each tooth to be a straight line. This necessitates the construction of the grip member in a somewhat polygonal form (as shown in dotted lines 19 in Figure 3) with double knuckle lines 20 lying parallel to the axis of the fitting. The double knuckle line allows the strip to be easily bent to form a regular polygon and in use permits the force to be transmitted directly via each tooth from the pipe wall to the wall of the sleeve member. Alternatively it is possible to form the teeth from an already curved strip material. In this case the knuckle line at the root of the tooth will be curved and the tooth curved as well as at 21 in Figure 3. Such an arrangement provides considerable strength of the tooth and will allow the grab ring to be curved rather than polygonal, as indeed is illustrated in Figure 3 in principle.

Claims (19)

1. A pipe coupling comprising a sleeve-like body portion formed with at least one open end; an annular grip member located within the sleeve member against an internal radial shoulder thereof, the grip member being so formed as to have a cylindrical outer wall located closely adjacent the internal wall of the annular sleeve member and having teeth extending from the outer cylindrical wall radially and axially inwardly of the coupling; said teeth being of such a length as to bite into the external periphery of a pipe to be connected with the couplings to inhibit removal thereof, and the grip member being so disposed and located within the sleeve as to constitute a pipe registry for locating the end of the pipe radially within the sleeve; an elastomeric annular sealing member disposed within the sleeve axially outwardly of the grip member; and means for locating the sealing member within the sleeve.

2. A pipe coupling as claimed in claim 1 wherein the grip member abuts, at its axially inner end, against an internal annular shoulder around the inner wall of the sleeve.

3. A pipe coupling as claimed in claim 1 or 2 wherein the grip member is provided with at least one radially inwardly extending prdjec- tion from the axially inner end thereof which extends radially inwardly of the outside diameter of the pipe to be connected so as to constitute an end stop or locator for the pipe within the sleeve.

4. A pipe coupling as claimed in any one of the preceding claims wherein the grip member is provided with at least one radially inwardly extending projection from the axially outer end thereof which extends radially inwardly a lesser distance than the outside diameter of the pipe to be connected, so as to assist in the radial location thereof within the sleeve.

5. A pipe coupling as claimed in any one of the preceding claims wherein the grip member is cut from strip material and them shaped into its generally cylindrical configuration.

6. A pipe coupling as claimed in any one of the preceding claims wherein the grip member is formed of any appropriate material such as a spring metal

7. A pipe coupling as claimed in any one of the preceding claims wherein the teeth are bent radially and axially inwardly from strips extending axially inwardly of the body of the grip member.

8. A pipe coupling as claimed in any one of the preceding claims wherein the cylindrical body of the grip member is provided with two or more rows of inwardly directed teeth spaced along the member.

9. A pipe coupling as claimed in claim 8 wherein teeth in different rows are of different length and at different angles of inclination.

10. A pipe coupling as claimed in any one of the preceding claims wherein the means for locating the sealing member within the sleeve constitutes an annular end insert member capable of insertion into the open end of the sleeve so as to locate and provide a compressive force upon the sealing member disposed therewithin.

11. A pipe coupling as claimed in any one of the preceding claims wherein the end insert member is removable.

12. A pipe coupling as claimed in any one of the preceding claims of double-ended form and having the same provision of grip member and sealing member at both ends.

13. A pipe coupling as claimed in claim 12 wherein the internal annular shoulder is located generally centrally of the coupling to locate the ends of pipes inserted therein.

14. A pipe coupling as claimed in any one of the preceding claims wherein the annular insert is a screw or a push-in or snap-in member.

15. A pipe coupling as claimed in any one of the preceding claims wherein the side walls of the sleeve taper away from the open end thereof or have a step reduction in diameter.

16. A pipe joint incorporating a coupling as claimed in any one of the preceding claims.

17. A grip member for a pipe coupling as claimed in any one of claims 1 to 5 comprising a strip of material bent into a cylindrical form having a plurality of teeth, cut from the cylindrical wall thereof, spaced theraround and projecting inwardly of the cylinder at an inclination to the axis thereof; and projections from the two ends of the cylinder extending radially inwardly to define openings of reduced diameter compared to that of the diameter of the cylinder.

18. A grip member as claimed in claim 17 wherein the inward projections at the two ends of the cylinder define openings of different magnitudes.

19. A pipe coupling substantially as shown in and as hereinbefore desribed with reference to the accompanying drawings.