GB2266569A - A push fit pipe connector with rolling gripping ring - Google Patents

Abstract

A connector 1 for connecting a first elongate member 2 by push fit connection with a second member 3 comprises a device 4 which has a portion bearing engagement means in the form of spaced apart teeth means 5, and is adapted to have relative rolling motion with respect to at least the first elongate member 2, suitably a UPVC pipe, and an internal tapered surface 6 of the second member 3 which is operative to provide said relative rolling motion and to drive the teeth means into biting engagement with the wall 7 of at least the first elongate member 2 on application of a load in a direction 'X' opposite to the push-in direction ('Y', Fig. 1) whereby to secure the members 2 and 3 together. Device 4 may be an endless helically wound spring made of square or circular section wire. <IMAGE>

Description

A CONNECTOR The invention relates to a connector, particularly for connecting a first elongate member such as a pipe by push fit connection with a second elongate member.

Pipes are often required to be connected together in pipe-lines there being connectors for this purpose. The pipes usually carry a fluid, often a liquid under pressure, and there is a tendency for the connections to leak because an '0' ring seal is unduly stressed at the connection, or because the pipes tend to separate at the connections.

It is an object of the invention to seek to mitigate these disadvantages.

According to the invention there is provided a connector for connecting a first elongate member by push fit connection with a second member, comprising a device which has a portion bearing engagement means and is adapted to have relative rolling motion with respect to at least the first elongate member, and a tapered surface of the second member which is operative to provide said relative rolling motion and to drive the engagement means into biting engagement with the wall of at least the first elongate member on application of a load in a direction opposite to the push-in direction, whereby to secure the members together.

The engagement may be teeth means, which may be provided by a helically wound spring portion of the device.

This provides a relatively simple way of providing a plurality of teeth in one element.

The whole device may comprise a helically wound spring. This provides for ease of construction, particularly where the spring is made of metal, preferably of stainless steel wire which may preferably be of substantially square cross section.

This last feature provides for additional gripping.

The first elongate member may comprise a pipe. This provides for providing a continuous pipeline in which different sections thereof are securely secured together.

The pipe may be a PVC or polyethylene pipe, particularly a UPVC pipe, which provides a relatively inexpensive system.

Alternatively, however, the pipe may be a metal pipe.

There may be a liner of the pipe at an end of the pipe which is inserted in the second member. The liner may be of metal. This provides support for the pipe against collapse inwardly thereof.

Alternatively there may be a sheath of the pipe at an end of the pipe in which in use the second member may be inserted, the sheath suitably being a metal sheath. This provides for support of the pipe against expansion.

The tapered surface, preferably an internal surface, may comprise a conical surface. This can therefore provide a continuous surface which therefore can provide a uniformly acting pressure applying means.

The second member may comprise metal, for example an elongate part of a flange adaptor. This provides a relatively simple flange connection for a pipe in a pipe-line system.

The second elongate member may comprise an internal annulus of diameter sufficient to allow passage of the first elongate member. This can act as a guide and support, and can provide a seating for seal means adjacent the flange.

The seal means may comprise an '0' ring on the side of the annulus adjacent the tapered surface.

A connector embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings.

Fig.1 is a schematic longitudinal section through a connector according to the invention on insertion of a first elongate member in a second elongate member; Fig.2 is a view similar to Fig. 1 on application of a load to the connector in a direction opposite the insertion direction; Fig.3 shows schematically forces applicable in the Fig.1 condition of the connector; and Fig. 4 shows schematically the forces applicable in the Fig.2 condition of the connector.

Referring to the drawings there is shown a connector 1 for connecting a first elongate member 2 by push fit connection with a second member 3 comprising a device 4 which has a portion bearing engagement means in the form of spaced apart teeth means 5, and is adapted to have relative rolling motion with respect to at least the first elongate member 2, suitably a UPVC pipe, and an internal tapered surface 6 of the second member 3 which is operative to provide said relative rolling motion and to drive the teeth means into biting engagement with the wall 7 of at least the first elongate member 2 on application of a load in a direction 'X' (Fig.2) opposite to the push-in direction 'Y' (Fig.1) whereby to secure the members 2 and 3 together.

The device 4 in the embodiment is an endless helically wound stainless steel spring formed of wire or the like of substantially square cross-section, the spring 4 having a rolling contact with the pipe 2, in other words the device 4, whilst being tightly mounted on the pipe 2 is nevertheless able to roll along the pipe 2 on application of a suitable force.

The spring is toroidal, like an '0' ring, in the embodiment, although it can be of any desired, suitable, configuration such as elliptical. Further it will be understood that the wire itself may have any desired shape, for example, of circular cross-section or substantially so.

The end 8 of the pipe 2 shown has an internal metal liner 9 which is cylindrical and has a nose 10 which is external to and extends round the end 8 of the pipe 2 to assist entry of the pipe 2 into the flange adaptor.

The liner body has a U-shaped cut out 9' which forms a tang 9" for digging into the pipe wall to secure the liner 9 in place.

The second member 3 is an elongate part 11 of a metal flange adaptor in the embodiment shown. The adaptor has a through bore 12 in which the pipe 2 is received.

The flange adaptor 3 has an end annulus 13 against which the inserted end 8 of the pipe 2 abuts at least initially, as shown in Fig. 1. Intermediate the length of flange adaptor 3 there is an internal annulus or wall 14 of a diameter just sufficient to receive the external surface of the pipe 2 in close sliding engagement, so the internal wall 14 acts as a guide and support for the pipe 2.

The wall 14 also provides a support or seating for a seal means which in the embodiment is in the form of a flexible 'O'ring 15.

It will be seen from Figs. 1 and 2 that the flange adaptor 3 has a cylindrical part 16 and a tapered or frusto-conical part 17 providing the tapered, frusto-conical surface 6, which surface 6 terminates in a cylindrical lip 18 which is also of a diameter to receive the outer diameter of the pipe 2 and then to support it too.

In use, to secure the pipe 2 in the flange adaptor 3 the '0' ring 15 is inserted in the bore 12 to seat against the internal wall 14. The spring device 4 is inserted in the bore 12 too, as shown in Fig.1. The pipe 2 is then offered up to the flange adaptor 3 and inserted therein in the direction of arrow 'Y' so that its inserted end 8 passes through the spring device 4, the '0' ring 15 and the internal wall 14 to build up against the annulus 13. This is the push-in direction.

In this position, the spring device 4 is located between the tapered surface 6 and the outer surface of the pipe 2 and grips the pipe because of the relative diameter dimensions thereof. However, in this position, the device 4 is not under load from the outer tapered surface.

If now a load is applied in the direction of the arrow 'X', Fig.2, the pipe tendency under the load is to move away from the annulus, a distance 'R' as shown in Fig.2. However, this tendency is opposed by the spring device 4, which is forced to roll along the pipe 2 with the pipe 2 as it engages the tapered surface 6. Moreover, as it does so, the tapered surface 6 forces the spring device 4 by its turns or coils to bite into or crush the surface of the pipe 2, there being longitudinal striations and a shoulder 19 formed on the surface of the pipe 2, by the spring device 4 as and where the spring device 4 crushes into the surface.This biting or crushing action is not sufficient to cause the pipe 2 to collapse as the pipe is supported by the liner 9, but the said action is sufficient to bind the pipe 2 and adaptor 3 together so that the pipe end 8 does not pass back beyond the '0' ring 15, so preserving the integrity of the seal.

The biting or crushing action is illustrated schematically in Figs. 3 and 4, Fig.3 corresponding to Fig.1 and Fig.4 to Fig.2. As shown, in Fig.1 the load vector resultant is nearly vertical, while in Fig.2 the resultant has moved to be nearer the axial, which greatly reduces the radial stress on the pipe and liner, an unexpected result of great significance as it means that a lighter duty (weight) adaptor and spring device can be used.

Stated in another way, the pipe 2 and liner 9 are stiff enough and strong enough in the radial direction to ensure that the spring device bites into or crushes into the outer surface of the pipe, and it is this deformed shape, as shown by the shoulder, which prevents the pipe 2 and liner 9 being crushed radially in toto.

Thus the integrity of the whole system is maintained whilst providing a positive sealing action.

It will be understood that modifications are possible. Thus the liner 9 may be omitted. Also, it will further be understood that the pipe and adaptor may be mounted together by the pipe 9 being engaged over the adaptor, in other words the adaptor part 11 is received as a push-fit in the pipe 9 which is necessarily of sufficient diameter to receive it. In this case the liner 9 may be mounted externally of the pipe 2, to prevent expansive disruption of the pipe 2, the spring device 4 being mounted internally of the pipe and externally of the part 11.

When axial loading is applied in the direction opposite the push-in direction the pipe and spring device roll relatively, and the tapered section again forces the spring device to bite and crush into the inner wall of the pipe 2, with the same locking effect as described before with respect to Figs. 1 and 2.

It will also be understood that the turns of the spring device 4, particularly where it is of square cross-section, effectively form teeth means. These teeth means may also effectively be formed by parts of a spring bar between radial cuts in the external surface thereof, by a plurality of discs on edge and mounted on a flexible resilient member to provide a spring effect, or by any suitable means. Also, although a circular spring means is described, a part spring means could be utilised, or two or more part spring means could be provided, providing they can be rollable on the pipe and bite or crush thereinto. Also, the pipe may be replaced by a solid rod.

In every embodiment the spring device 4 has a high enough friction coefficient when mounted against the surface of the pipe 2 so that when the pipe moves in the direction opposite to the push-fit direction, the device 4 rolls rather than slides along the pipe (Fig. 2 for example). The device 4 accordingly has a compliance and a circumference such that it expands slightly when the pipe 2 is pushed in (Fig. 1) so that the device then grips down on the pipe. Moreover, the material of the device 4 is such that the device has a relatively low bending stiffness so that it can be turned inside out as it rolls along the pipe to enhance rolling, and thus the crushing and gripping action.

In addition, it will be understood that the device 4 itself has a high enough strength or stiffness in compression so that it does not itself collapse when it is engaged by the tapered surface 6.

Finally, shims may be provided for inserting into the adaptor to release the pipe and spring means so that the adaptor and pipe can be separated.

Claims (21)

1. A connector for connecting a first elongate member by push fit connection with a second member, comprising a device which has a portion bearing engagement means, and is adapted to have relative rolling motion with respect to at least the first elongate member, and a tapered surface of the second member which is operative to provide said relative rolling motion and drive said means into biting engagement with the wall of at least the first elongate member on application of a load in a direction opposite to the push-in direction, whereby to secure the members together.

2. A connector according to Claim 1, the engagement means being spaced apart teeth means.

3. A connector according to Claim 2, the teeth means being provided by a helically wound spring portion of the device.

4. A connector according to Claim 3, the whole device comprising a helically wound spring.

5. A connector according to Claim 4, made of metal.

6. A connector according to Claim 5, made of stainless steel.

7. A connector according to Claim 6, the spring being made of wire or the like of substantially square cross-section.

8. A connector according to any preceding claim, the first elongate member comprising a pipe.

9. A connector according to Claim 8, the pipe being a PVC or polyethylene pipe.

10. A connector according to any one of Claims 1 to 8, the pipe being a metal pipe.

11. A connector according to any of Claims 8 to 10, including a liner of the pipe at an end of the pipe which is inserted in the second member.

12. A connector according to Claim 11, the liner comprising a metal liner.

13. A connector according to any of claims 8 to 10, including a sheath of the pipe at an end of the pipe in which in use the second member is inserted.

14. A connector according to Claim 13, the sheath being a metal sheath.

15. A connector according to any preceding claim, the tapered surface comprising a conical surface.

16. A connector according to any preceding claim, the second member comprising metal.

17. A connector according to Claim 16, the second member comprising an elongate part of a flange adaptor.

18. A connector according to Claim 16 or Claim 17, the second elongate member comprising an internal annulus of diameter sufficient to allow passage of the first elongate member.

19. A connector according to Claim 18, including seal means adjacent the flange.

20. A connector according to Claim 19, the seal means comprising an 'O' ring on the side of the annulus adjacent the tapered surface.

21. A connector for connecting a first elongate member by push fit connection with a second member, substantially as hereinbefore described with reference to the accompanying drawings.