WO2004104466A1

WO2004104466A1 - Tube coupling device

Info

Publication number: WO2004104466A1
Application number: PCT/GB2004/002186
Authority: WO
Inventors: Karl Andrew Evans; Russell Luke Wilson
Original assignee: Yorkshire Fittings Limited
Priority date: 2003-05-22
Filing date: 2004-05-21
Publication date: 2004-12-02
Also published as: GB0311760D0

Abstract

A pressure fluid tube coupling device comprises a body (3) adapted for insertion into a tube (2) to be coupled to the device, the body (3) having a through passage (8), and on an outer surface sealing means for forming a fluid-tight seal between an internal surface (5) of the tube (2) and the body (3), and gripping means (4, 31) adapted for engagement with the internal surface (5) of the tube (2), to retain the tube (2) on the body (3) after manual assembly of the tube (2) and the body (3).

Description

TUBE COUPLING DEVICE

This invention relates to a coupling device for coupling tubes, in particular plastics or composite tubes or pipes, in a fluid-tight manner. From now on, the term 'tube' will be used to encompass tubes and pipes.

Most known coupling devices have a body with a bore designed to receive the tube, and include a seal for sealing against the outside of the tube and a grip ring adapted to grip the outside of the tube to prevent its removal. Typically, a movable locking element is used to urge the seal and the grip ring into engagement with the tube. Such coupling devices tend to be difficult to assemble, because all the parts are inside the body. They may also be relatively time-consuming in use, because of the need to engage the movable locking element.

According to the present invention, a pressure fluid tube coupling device comprises a body adapted for insertion into a tube to be coupled to the device, the body having a through passage, and on its outer surface sealing means for forming a fluid-tight seal between an internal surface of the tube and the body, and gripping means adapted for engagement with the internal surface of the tube, to retain the tube on the body after manual assembly of the tube and the body.

The coupling device of the invention is easier to assemble, as the gripping means and sealing means are located on the outside of the body, not the inside. It is also easy to use, as it simply requires inserting into the end of the tube.

The sealing means may simply comprise the tube and the body, the arrangement being such that the seal is made by interference between the body and the tube. This is advantageous where the internal surface of the tube is of plastics .

Alternatively, the sealing means may comprise one or more seals mounted in respective external grooves on the body.

Preferably two spaced seals are provided, each within a respective external groove. The seal or seals are preferably located axially outwardly of the grip ring, so that in use they are further than the grip ring from the end of the tube. However, they could be inwardly of the gripping means, or where there are two seals, one each side of the gripping means. The or each seal is preferably an O-ring.

The gripping means preferably comprises a split grip ring accommodated in an external groove on the body. The grip ring may comprise a toothed member having at least one tooth or serration. The grip ring groove has an axially outer face inclined to the axis of the body and an axially inner face perpendicular to the axis, with which respective complementary axially outer inclined and axially inner perpendicular faces on the toothed member are adapted to engage. The axial length of the toothed member is less than that of the groove. On insertion of the body into the tube the toothed member is moved so that the perpendicular faces engage, with the toothed member in its radially inmost position where there is a minimum or even no engagement between the teeth and the internal surface of the tube. If the tube and body are pulled apart, the toothed member is moved so that the inclined faces engage, and the toothed member in effect moves up a ramp and therefore radially outwardly, to increase the engagement between the teeth and the tube. This prevents the disengagement of the body and tube. Alternatively, the grip ring may comprise a toothed member held in the gripping groove by a retaining ring. The grip ring preferably has an axially-extending part held by the retaining ring, and an inclined part having the teeth. The teeth are arranged so as to flex radially inwardly on insertion of the body into the tube, and then outwardly into engagement with the internal surface of the tube. However, if the tube and the body are pulled apart, the teeth flex outwardly to increase the engagement between the teeth and the tube.

While the gripping means and seal or seals may occupy their own respective grooves, it is also possible for them to share a common groove.

The body may be of metal or plastics. If it is of plastics, a toothed grip ring may be moulded integrally with the body.

Preferably, the body has a stop to define the end position of the end of the tube. The stop may be an external projection on the body.

One embodiment of the device also includes a further retaining means for the tube. The retaining means conveniently comprises a rigid sleeve fixed at one end to a central part of the body, and with its opposing free end projecting towards the free end of the body. The sleeve is spaced from the external surface of the body, to define an annular gap which receives the tube when the body is inserted into the tube. The sleeve holds the end of the tube firmly in place.

The rigid sleeve is preferably fixed to the body by an inturned flange which fits in a further external groove in the body. The further external groove may be provided in the stop projection. However, any suitable way of fixing the sleeve, such as by a bayonet connection, by crimping or adhesive, could be used.

Normally the coupling device is designed so that the tube, once inserted, cannot be removed. In one embodiment, however, the gripping means is arranged so that its gripping engagement with the tube is releasable. This is achieved by providing the gripping means with a radial flange projecting outwardly beyond the external diameter of the tube. When the engagement is to be released, the gripping means is moved, using the flange, down the ramp to release the teeth.

It will be appreciated that the body of the device may be arranged for the coupling of two tubes, or for the coupling of a tube to a further fitting.

Various embodiments of the invention are illustrated in the accompanying drawings, in which

Figure 1 is a longitudinal section through a coupling device, showing a tube fitted to one end;

Figure 2 is similar to Figure 1, but shows a modified device;

Figure 3 shows a further modification; and

Figure 4 is similar to Figure 3, but shows a further embodiment.

The coupling device 1 of Figure 1 is for coupling two plastics tubes 2, for example for use in domestic water systems, in a fluid-tight manner. Only one tube 2 is shown, on the right-hand side of the Figure, the left-hand side being shown before a tube is attached. The device 1 comprises a metal body 3 carrying a gripping means in the form of a grip ring 4 for engagement with an internal surface 5 of the tube 2 to retain the tube on the body 3, and two seals 6,7 for sealing in a fluid-tight manner between the internal surface 5 of the tube 2 and the body 3.

The body 3 may be formed from a machined casting or a machined bar, and has a straight through-bore 8, and a profiled external surface 9. Only one end of the body 3 will be described, as the other end is a mirror- image.

The free end 10 of the body 3 is frusto-conical in shape, for ease of insertion into the tube 2, while the central portion 11 has a projection 12 forming a stop for the end of the tube 2. Adjacent the projection 12 the body 3 has an external groove 13 in which the grip ring 4 is received. Two further external grooves 14 are formed adjacent the free end 10 for receiving the seals 6,7.

The seals 6,7 are O-rings, received in annular grooves 14. The groove 13 for the grip ring 4 has an axially inner face 15 perpendicular to the axis of the body 4, a straight base portion 16 parallel to the axis of the body 3 and an axially outer face 17 having a portion 18 contiguous with the base 16 and inclined to the axis, and a radially outer portion 19 perpendicular to the axis again.

The grip ring 4 is an externally toothed split metal member with four teeth 20 on its external surface. The grip ring also has an axially inner face 21 perpendicular to the axis of the body 3, and corresponding to the inner face 15 of the groove 13, a straight base 22 complementary to the base 16 of the groove 13, and an axially outer face 23 with an inclined portion 24 and a perpendicular portion 25, corresponding to the outer face 17 of the groove 13. Each tooth 20 has an axially inner radially extending face 26 and an axially outer inclined face 27.

To assemble the device 1 the grip ring 4 is first put onto the body 3 into the groove 13, and then the O-rings 6,7 are pushed on from the free end, into their grooves 14, as shown in the left-hand side of Figure 1. It will be appreciated that the O-rings project radially out of the grooves 14, and that the teeth 20 of the grip ring 4 also project radially out of the groove 13.

In use, in order to attach a tube 2 to the device 1, it is simply necessary for the user to insert the free end 10 of the body 3 into the free end of the tube 2, and to push the two together. The body 3 will be inserted until the end of the tubes 2 engages the projection 12. As the body is inserted the O-rings 6,7 are compressed against their grooves 14 and the internal surface 5 of the tube, to ensure a sealing engagement. The grip ring 4 is carried axially inwardly until its face 21 engages the corresponding face 15 of the groove 13. The teeth 20 still project radially out of the groove 13, and engage with the internal surface 5 of the tube 2, to retain it in position.

If a force is applied to move the tube 2 and body 3 relatively away from each other, the tube 2 will tend to carry the grip ring 4 axially outwardly. The inclined portions 18 and 24 will engage, causing the grip ring 4 to ride up radially outwardly, away from the base of the groove 13, thus increasing the engagement between the tube 2 and the grip ring 4, tending to prevent the separation of the tube 2 and the body 3. If the force is removed, the grip ring 4 will tend to return to the position shown on the right-hand side of Figure 1, which returns the tube 2 as well. The coupling device 1 is therefore easy to assembly and install, and will tend to prevent removal.

If, however, further retention of the tube 2 is necessary, perhaps because of a higher fluid operating pressure, the embodiment of Figure 2 may be used. Figure 2 shows a modification of the embodiment of Figure 1, and corresponding reference numerals have been applied to corresponding parts.

In the embodiment of Figure 2 the grip ring 4 is modified, and the body 3 is modified accordingly. The body 3 is also modified in order to accommodate the further retention means 30. The seals 6,7 and their grooves 14 are unchanged.

The groove 13 for the grip ring 4 has axially inner and outer faces 15,17 which are perpendicular to the axis of the body 3. The grip ring 4 comprises an annular toothed metal member 31 having a first portion 32 extending axially and held in the base of the groove 13 by a retaining ring 33, and a second portion 34 inclined to the axis, with teeth 35 on its free end adapted to engage with the internal surface of the tube 2.

The projection 12 is enlarged, and itself has a groove 36 adapted to receive a flange 37 of a rigid sleeve 38 forming the further retention means 30.

The sleeve 38 is of metal and surrounds the body 3, with a gap 39 for receiving the tube 2 being defined between the external surface of the body 3 and an internal surface 40 of the sleeve 38. The flange 37 is turned in, and engages the body 3 in the groove 36, while the opposing end 41 of the sleeve 38 is slightly flared, to assist in assembly of the tube 2 and the body 3. The coupling device 1 of Figure 2 is assembled in a similar way to that of Figure 1, with the member 31 being retained in the groove 13 by the ring 33, then the O-rings 6,7 being inserted into the grooves 14, and finally the sleeve 38 being put in place in the groove 36. It will be noted that the teeth 35 of the member 31 project radially beyond the body 3, while the O-rings 6,7 also project radially beyond the body 3, as in Figure 1.

In use, to attach a tube 2 to the device 1, it is simply necessary for the user to insert the free end 10 of the body 3 into the free end of the tube 2, with the tube 2 occupying the space 39, and to push the two together. The body 3 will be inserted until the end of the tube 2 engages the projection 12. As the body 3 is inserted into the tube 2 the O-rings 6,7 are compressed against their grooves 14 and the internal surface 5 of the tube, to ensure a sealing engagement. The inclined second portion 34 of the member 31 is deflected radially inwardly by the tube 2, but when the tube reaches the stop 12 it returns to engage with the internal surface of the tube 2. The sleeve 38 grips the external surface of the tube 2.

If a force is applied to move the tube 2 and body 3 relatively away from each other, the inclined portion 34 of the member 31 will be deflected radially outwardly, increasing its engagement with the tube 2, tending to prevent the separation of the tube 2 and the body 3. If the force is removed, the member 31 will return to the position shown on the ring- hand side of Figure 2, which returns the tube 2 as well.

Figure 3 shows a further modification of Figure 1, and again corresponding reference numerals have been applied to corresponding parts. Figure 3 shows only the body 3, and not the tube 2. In Figure 3 there is only one seal 6 in a respective groove 14. The grip ring 4 is modified, and is of triangular section, having in effect a single tooth 20. The grip ring groove 13 has an increased axial length, and no straight base portion 16. Otherwise, the construction and operation of the embodiment of Figure 3 is the same as that of Figure 1.

The devices shown in Figures 1 to 3 are designed as permanent couplings, so that the tube 2 cannot be removed from the body 3.

The embodiment of Figure 4 shows a coupling device which allows for removal of the tube 2, and therefore re-use of the device. The embodiment of Figure 4 is a modification of the embodiment of Figure 3 and corresponding reference numerals have been applied to corresponding parts.

In Figure 4 a single seal 6 and groove 14 are provided. The grip ring groove 13 is extended axially inwardly, right up to the stop projection 12 and has a straight base portion 16. The grip ring 4 is significantly modified. Thus, the grip ring 4 has a single tooth 20 at its axially outer end, adjacent to an external groove 45. The grip ring 4 then has a central portion 46 of constant external diameter less than the internal diameter of the tube 2, and terminates at its axially inner end in a radial flange 47 which projects outwardly beyond the external diameter of the tube 2. The end face 48 of the flange 47 is adjacent the stop projection 12, while the opposing face 49 forms the stop for the tube 2.

In use, the tube 2 is assembled on the body 3 in the same way as in the previous embodiments, by being pushed on, until the end of the tube 2 reaches the face 49 of the flange 47. A slight retraction of the tube 2 then pulls the grip ring 4 up the ramp of the groove 13, to cause the tooth 20 to engage firmly in the internal surface of the tube 2. After assembly, therefore, there will be an axial gap (not shown) between the end 48 of the flange 47, and the projection 12.

If the tube 2 is to be removed from the body 3, the user moves the grip ring 4 (by means of the flange 47) back into engagement with the projection 12, so that the tooth 20 is released from engagement with the tube 2. The tube 2 can then be pulled off the body 3, while the grip ring 4 is held against the projection 12.

Various modifications of the device are possible. For example, the position of the grip ring 4 and seal or seals 6, 7 could be reversed. If two seals are provided, they could be arranged one each side of the grip ring 4. It would also be possible for a seal 6 and the grip ring 4 to share a common groove.

The body 3 may be of plastics, rather than metal. It would then be possible to mould the teeth 35 of the grip ring of Figure 2 integrally with the body 3, so that the retaining ring 33 is not required.

The embodiments shown therefore provide a coupling device which is easy to assemble, and easy to use.

Claims

1. A pressure fluid tube coupling device comprises a body (3) adapted for insertion into a tube (2) to be coupled to the device, the body (3) having a through passage (8), and on an outer surface sealing means for forming a fluid-tight seal between an internal surface (5) of the tube (2) and the body (3), and gripping means (4, 31) adapted for engagement with the internal surface (5) of the tube (2), to retain the tube (2) on the body (3) after manual assembly of the tube (2) and the body (3) .

2. A tube coupling device according to claim 1, in which the sealing means comprises the tube (2) and the body (3), the arrangement being such that the seal is made by interference between the body (3) and the tube (2).

3. A tube coupling device according to claim 1, in which the sealing means comprises one or more seals (6, 7) mounted in respective external grooves (14) on the body (3).

4. A tube coupling device according to claim 3, in which two spaced seals (6, 7) are provided, each within an external groove (14).

5. A tube coupling device according to claim 3 or claim 4, in which the seal or seals (6, 7) are located axially outwardly of the grip ring (4, 31).

6. A tube coupling device according to claim 3 or claim 4, in which the seal or seals (6, 7) are located axially inwardly of the grip ring (4, 31).

7. A tube coupling device according to claim 4, in which the two seals (6, 7) are located one on each side of the grip ring (4, 31).

8. A tube coupling device according to any of claims 3 to 7, in which the or each seal (6, 7) is an O-ring.

9. A tube coupling device according to any preceding claim, in which the gripping means comprises a grip ring (4, 31) accommodated in an external groove (13) on the body (3).

10. A tube coupling device according to claim 9, in which the grip ring (4, 31) is split.

11. A tube coupling device according to claim 9 or claim 10, in which the grip ring (4, 31) comprises a toothed member having at least one tooth or serration (20, 35).

12. A tube coupling device according to any of claims 9 to 11, in which the grip ring groove (13) has an axially outer face (17) inclined to the axis of the body (3) and an axially inner face (15) perpendicular to the axis, with which respective complementary axially outer inclined (23) and axially inner perpendicular faces (21) on the grip ring (4) are adapted to engage.

13. A tube coupling device according to claim 11 or claim 12, in which the axial length of the grip ring (4) is less than that of the groove (13).

14. A tube coupling device according to claim 11, in which the grip ring comprises a toothed member (31) held in the gripping groove (13) by a retaining ring (33).

15. A tube coupling device according to claim 14, in which the grip ring (31) has an axially extending part (32) held by the retaining ring (33) and an inclined part (34) having the tooth or teeth (20, 35).

16. A tube coupling device according to any of claims 3 to 15, in which the gripping means (4, 31) and seal or seals (6, 7) occupy their own respective grooves (13, 14).

17. A tube coupling device according to any of claims 3 to 15, in which the gripping means (4, 31) and seal or seals (6, 7) share a common groove.

18. A tube coupling device according to any preceding claim, in which the body (3) is of metal.

19. A tube coupling device according to any of claims 1 to 17, in which the body (3) is of plastics.

20. A tube coupling device according to claim 19, in which a toothed grip ring (4) is moulded integrally with the body (3) .

21. A tube coupling device according to any preceding claim, in which the body (3) has a stop (12) to define the end position of the end of the tube (2) .

22. A tube coupling device according to claim 21, in which the stop (12) is an external projection on the body (3).

23. A tube coupling device according to any preceding claim, in which the device includes further retaining means (30) comprising a rigid sleeve (38) fixed at one end to a central part of the body (3), and with its opposing free end projecting towards the free end of the body (3).

24. A tube coupling device according to claim 23, in which the sleeve (38) is spaced from the external surface of the body (3), to define an annular gap (39) which receives the tube (2) when the body (3) is inserted into the tube (2) .

25. A tube coupling device according to claim 23 or 24, in which the rigid sleeve (38) is fixed to the body by an inturned flange (37) which fits in a further external groove (36) in the body (3) .

26. A tube coupling device according to claim 25, in which the further external groove (36) is provided in the stop projection (12).

27. A tube coupling device according to any preceding claim, in which the gripping means (4, 31) is arranged so that its gripping engagement with the tube is releasable.

28. A tube coupling device according to claim 27, in which the gripping means (4, 31) is provided with a radial flange (47) projecting outwardly beyond the external diameter of the tube (2) .

29. A tube coupling device according to any preceding claim, in which the body (3) of the device is arranged for the coupling of two tubes (2) .

30. A tube coupling device according to any of claims 1 to 28, in which the tube coupling device is arranged to couple a tube (2) to a further fitting.