GB2336637A - Pipe joint - Google Patents

Abstract

The joint 2 comprises a socket 6 for receiving a pipe 12; and a radially deformable member 24 for insertion between a radially inner surface of the socket and a radially outer surface of the pipe and adapted to maintain radial separation of the radially inner surface of the socket and the radially outer surface of the pipe in a first circumferential region of the socket, i.e. the top and maintain radial proximity between the radially inner surface of the socket and the radially outer surface of the pipe in second circumferential region of the socket, i.e. the bottom. The joint can be used to couple pipes of various diameters with ease. It also provides a smooth lower flow surface, so as to resist blockages. The socket 6 and member 24 are frusto-conical with their axes angled from the joint axis. Movement of the member 24 for sealing a pipe 12 is by a clamp lever 30 coupled to the member and camming against a socket surface or vice versa. The lever may have force limiting means at its pivot to avoid over-clamping of the member 24.

Description

1 M&C Folio: 230P78080 PIPE JOINT 2336637 The present invention relates to

a pipe joint and also to a clamp member for use with a pipe joint and a clamping mechanism for use with the clamp member. The invention has particular, although not exclusive, relevance to pipe joints having diameters in the range of 150mm to 30Omm such as used in sewerage systems and the like.

The jointing of pipes in sewerage systems, whether directly together or via an intermediate coupling member, should at least meet the following objectives. First, the joint needs to befluid-tight. This means that any fluid flowing through or past the joint between respective pipes must not leak out of the system and the joint must prevent external around water from leaking into the system. Second, any joint should be able to withstand a variable load being placed upon it. Such a load may vary by way of differing rates and volumes of fluid flow through the joint or even by way of external pressure placed upon the system. Pressure variation may occur when a coupling is buried underground, for example beneath a roadway, and the weight of traffic travelling along the roadway varies, thereby creating a variable pressure load upon the joint. The system might also, for example, experience loading due to ground subsidence.

Known pipe joints can be divided into two basic categories. The first type ofjoint is a spigot and socket joint, in which a spigot from one pipe is inserted within a socket from another. Such ajoint is relatively simple and economical to manufacture, but it is relatively poor at accommodating radial loads without creating stresses in the pipe.

The other aeneral type of joint is a coupling joint, in which an intermediate coupling 0 I,> connects two lengths of pipe. This tends to allow more movement, and hence accommodate radial and axial loads more easily than a spigot and socket joint, but still provides a good seal. However, problems with such joints are not unknown, because the flow path running over the three connected components can present radial 2 interruptions, which can disturb fluid flow, collect debris and ultimately result in a blockaae.

0 The present invention sets out to provide a coupling joint which enables the fluid flow surface of a joint to be relatively smooth.

It is desirable for a single coupling joint to be capable of connecting pipes having a 0 -5 ranae of diameters. If this is achieved, fewer sizes of coupling need to be manufactured c - thus reducing manufacturing costs. Furthermore, a smaller range of couplings needs to be stored on site and there is a reduced risk of a fitter fittin the wrong sized coupling 9 C.1 to a pipe end.

In an attempt to address this problem, known couplings include very flexible radially inner ring seals, in order to accommodate differences in pipe diameter whilst maintaining a good seal. Typically, to enable the pipes to be physically jointed on site the maximum radial seal compression will be of the order of 30-40%. To maintain a reliable seal and provide good radial and axial support, the minimum possible seal compression will be of the order of 10-15%. The consequence of these two largely conflicting requirements is that such a seal will typically be manufactured from a relatively large volume of relatively expensive material.

0 The present invention also seeks to provide a coupling in which the volume of sealing material required to manufacture the internal radial seals is relatively small.

With relatively large diameter pipes, a further problem is experienced in that it can be difficult to fit couplings to the ends of pipes. This is because the forces required are relatively high. Typically, a fitter will fit a coupling to a pipe end by standing the length of pipe upright, locating the coupling over the upper pipe end and pulling the coupling down onto the pipe end. This enables the fitter to generate the necessary axial forces much more easily than when the pipe is orientated horizontally. However, with pipes of relatively large diameter (such as 225mm and 30Omm pipes) the pipe cannot be 3 stood upright (due to size and weight) and hence this fitting method cannot be employed. Unfortunately, it is with such diameter pipes that the upright fitting method 0 would be most useful, because the axial forces required are greater with such a pipe mainly because the seal referred to above will be experiencing close to maximum deformation as the joint is made This fitting problem has been addressed by pre-fitting coupllnc,,s onto relatively large diameter pipes at the factory. However, this solution is not satisfactory for three main reasons. First, it adds to the manufacturing expense and ultimately the unit cost to the purchaser. Second, because the couplings are stored in conjunction with the pipes, they tend to become dirty and debris may be trapped inside the couplings, thereby eventually degrading the seal after the piping has been installed. Third, if couplings are pre-fitted, there is less alignment flexibility at installation.

The present invention therefore also sets out to provide a pipe coupling which can easily be fitted to relatively large diameter pipes, even when the pipes are aligned horizontally.

According to a first aspect of the present invention, there is provided a pipe joint comprising. a socket for receiving a pipe member and a radially deformable member for insertion circumferentially between a radially inner surface of the socket and a radially outer surface of the pipe member, wherein the radially deformable member is adapted to maintain radial separation of the radially inner surface of the socket and the radially outer surface of the pipe member in one circumferential region of the socket and maintain radial proximity between the radially inner surface of the socket and the radially outer surface of the pipe member in another circumferential region of the socket.

Provision of a radially deformable member allows for not only alignment of the socket and the pipe so that the lower flow surface is smooth and has no steps, unlike the prior art, but also this provision enables the joint to couple easily with pipes of differing

4 diameters. Provision of such a radially deformable member also enables the deformation range of any seal to be lower than in the known couplings. This means that seals can be made much smaller than has hitherto been the case and this provides a significant cost saving and consistent sealing performance with all pipe diameters.

Preferably the radially deformable member is a radially deformable clamp.

Preferably the radially deformable clamp is defined by a ring having a varying radial thickness around its circumference and advantageously the clamp comprises a discontinuous ring. In the case of the radially deformable clamp comprising a 0 1-P discontinuous ring, this assists with provision of a smooth lower flow surface, if the ring is split in the axial direction. Advantageously the radial thickness of the clamp increases for 180' around its circumference and then decreases for 180' around its circumference, starting from a point of minimum thickness.

1 In a preferred embodiment, the radial proximity between the radially inner surface of the socket and the radially outer surface of the pipe is such that axially extending portions of radially inner surfaces of the socket and the pipe lie substantially flush with each other.

Preferably, the clamp has a frustoconical radially outer surface and the socket has a frustoconical radially inner surface, against which the frustoconical radially outer surface of the clamp bears during use. In such a case, radial contraction of the clamp is achieved by urging the clamp into the socket in the axial direction.

1 A means for axially urging the clamp into the socket may be included. This means may comprise a generally circular ring having a portion of an axially inwardly facing surface axially raised with respect to the remainder of that surface such that rotation of the ring, causes the raised surface thereof to slide over a generally axially facing, but inclined camming surface of the radially deformable clamp.

Alternatively the means may comprise a mechanism including a cam surface for bearing against a generally axially facing bearing surface provided on one of the socket and the clamp and a lever which is pivotally connected to the other of the socket and clamp about a pivot axis perpendicular to the axial direction, such that rotating the lever about the pivot axis brings the cam surface to bear against the said bearina surface and continued rotation of the lever about the pivot urges the clamp axially further into the socket.

Preferably, the bearing surface is provided inwardly.

on the socket and faces generally axially Preferably there is a ring seal for location between a radially inner surface of the socket and a radially outer surface of the pipe member. The ring seal may abut the radially deformable clamp or may be connected therewith- It is a further object of the present invention to provide a radially deformable member for use with such a pipe coupling. It is yet a further object of the present invention to provide a clamping mechanism for use with a pipe coupling and/or a clamp member as discussed above.

According to a second aspect of the present invention, there is provided a radially deformable clamp member for a pipe coupling having a radial thickness varying around a circumference thereof, such that the thickness increases over 180' around the circumference, then decreases over the next 180' around the circumference, starting from a point of minimum thickness. A clamp member having these features enables clamping of articles of differing dimensions more readily than has hitherto been the case.

Preferably the clamp member is generally ring-shaped and may be discontinuous.

0 6 Accordina to a third aspect of the present invention, there is provided a clamping mechanism comprising a first body and a second body to be moved in a first direction relative to the first body and secured in a clamped relationship therewith; wherein the mechanism further comprises an arm and a pivot, the said arm being journalled to the first body by the said pivot, the pivot axis being generally perpendicular to the said first direction, and one of the arm and first body being translatable relative to the pivot axis, or vice versa, in a plane perpendicular to the pivot axis and the other of the arm and the said first body not being translatable relative to the said pivot axis in the said plane; the second body comprises a bearing surface facing generally in the said first direction., the said arm comprises a cam surface for bearing against the said bearing surface when the arm is rotated about the pivot. and resistance means is provided for resisting the said relative translation between the pivot axis and the said one of the arm and first body; the arrangement being such that rotation of the arm from a non- clamping position towards a clamping position causes the cam surface to bear against the bearing surface, which initially urges the first body in thefirst direction until a predetermined resistive force is experienced, after which further rotation of the arm causes relative translation between the pivot and the said one of the arm and the first body, reversal of the said translation being resisted by the said resistance means, which thereby serves to secure the rotational portion of the arm when the applied rotational force is released.

Such a mechanism makes it possible for a fitter to apply the same clamping force to a clamp member for clamping articles having a range of different dimensions. The force is automatically controlled without the need for manual intervention.

Preferably the first body comprises a radially deformable member.

Preferably the pivot is movably housed within a channel provided in the arm or the first body in order to enable the said translation to occur. Advantageously the said resistance 7 means is a ratchet mechanism housed within the channel. In one particularly preferred embodiment, the channel is provided with a series of ridges and a portion of the pivot located within the channel is provided with a resiliently projecting dog which can move across the ridges when a predetermined turning force is applied to the arm, but locates behind one of the ridges to resist reversal of the said translation when the turning force is removed.

The clamping mechanism according to this aspect of the invention may be used as the said means for axially urging the clamp into the socket in the first aspect of the invention.

The present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

0 Figure 1 shows part-sectioned side views of a first embodiment of pipe coupling in accordance with the present invention; Figure 2 shows an end view along arrow B of Figure 1; Figure 3' shows a sectional view of a second embodiment of a pipe coupling in an unclamped position; Figure 4 shows a sectional view of the second embodiment clamping two pipes of different diameters; Figure 5 shows a view from above the second embodiment of the invention; Figures 6, 7 and 8 show various stages in the operation of clamping one end of a third embodiment of a coupling to a pipe presented thereto; 8 Figures 9 and 10 show a similar operation to Figures 6 to 8, but in the case where the 1 c pipe being clamped has a smaller diameter; Figures 11 (a) and 1 1(b) show an alternative clamping tool in accordance with the present invention; Figure 12 (a) to 14 show details of alternative clamping mechanisms in accordance with 0 the present invention; Figure 15 schematically shows the principle of operation of the clamping mechanisms of figures 12(a) to 14.1 Figure 16 shows a perspective view of a radially deformable clamp in accordance with the present invention; Figure 17 shows a plan view of the clamp of Figure 16,- and Figures 18 and 19 respectively show bottom and side views of the clamp of Figures 16 and 17.

Referring first to Figure 1, it can be seen that a pipe coupling means includes a coupling piece 2 comprising a central tubular section 10 provided with a central radially inwardly directed flange 4, and, at each axial end, an eccentrically flared mouth 6. As can be seen more readily from the right-hand side of Figure 1, the tubular section 10 accommodates a pipe for mating with the coupling piece 2. It can be seen that the coupling piece 2 is a mirror image about the central flange 4. In this way, therefore, a pipe for coupling can be accepted from either or both ends of the coupling piece 2. Referring also to Figure 2, which is an endon view of Figure 1 from arrow B, it can be seen that the axially inner surface of the flared mouth 6 is frustoconical. The orientation of this surface is defined by a virtual cone having a generatrix G, a cone axis CA and a vertex V (not shown). It is important to note that the cone axis CA is not parallel with the primary longitudinal axis AX of the coupling or, indeed, with the longitudinal axis of a pipe 12, once inserted. The cone axis is, instead, inclined at an 9 angle (x from the primary longitudinal axis AX of the coupling. This relationship is 1 illustrated in Figures 1 and 3.

It will be noted from Figure 1 that the angle (x between the cone axis CA and the primary longitudinal axis AX of the coupling is in fact the same angle as between the 0 cone axis CA and the generatrixG of the cone. Consequently, the surface of the virtual cone and hence the frusto-conical surface of the mouth 6 is aligned to be parallel with the primary axis of the coupling at the bottom of the coupling.

Coupling piece 2 is formed from clay or plastics and is moulded in a known manner.

For illustrative purposes, as can be seen most readily from Figure 2, the pipe to be coupled 12 has an outer diameter which is significantly smaller than the axially innermost radially inner diameter (excluding that defined by the central flange 4) of the coupling piece 2, which it addresses. It can be seen that a gap 14 exists between the radially outer surface of the pipe 12 and the uppermost portion of the radially inner wall 16 of the tubular section 10. Pipes of other diameters can, however, be used with this coupling. The reasons for this will become apparent below.

Referrin. now to the left-hand portion of Figure 1, it can be seen that a radially deformable clamp 18 is disposed within the bounds of the lefthand coupling mouth 6. In practice, a similar clamp would be located in the right-hand mouth of the coupling but it is not shown in the interests of clarity. In this example the clamp takes the form of a wedge ring 18 made of a resilient plastics material. The configuration of ring 18 can be seen most clearly in Figure 16, which shows it in isolation.

The radial contraction of the ring 18 is achieved by the presence of the axial split 60. As a radial force is applied to it, the two arms shown as 62 and 64 are urged together and this allows the contraction to occur. There is no necessity for such a gap to exist, 0 but in the embodiments shown this gap is present. Those skilled in the art will appreciate that a wedge ring in accordance with the present invention may operate efficaciously with a complete ring structure, providing it can be collapsed radially.

0 The radially outer surface of the wedge ring 18 has a frusto-conical surface. This frusto-conical surface is based upon a virtual cone which is substantially identical to the virtual cone forming the basis for the frusto-conical radially inner surface of the mouth 6. However, as can be seen in Figure 3, in its relaxed state the radially outer surface of the wedge ring 18 corresponds with a portion of the virtual cone that is situated further from the vertex of the virtual cone than is the frustoconical radially inner surface of the mouth 6.

If a conical structure is inserted into a conical mouth having a corresponding angle between its axis and generatrix, then the structure will tend to align its axis with that of the mouth. Although the wedge ring 18 and the mouth 6 of the present invention are not complete cones, the respective frusto-conical surfaces will behave in the same manner when the wedge ring 18 is inserted into the mouth 6. Consequently, when the wedge ring 18 is first inserted into the mouth 6, it will align its radially outer surface with the radially inner surface of the socket mouth. Of course, when the surfaces fully abut each other, further insertion will be resisted. However, as described, the wedge ring 18 is radially collapsible, which allows it to contract such that it can be inserted further into the socket mouth. In practice, further insertion will maintain the coaxial relationship.

The pipe-addressing radially inner surface of the wedge ring 18 is generally tubular and axially aligned with the primary axis AX of the coupling. It is also situated towards the bottom of the wedge ring, such that it is generally aligned with and relatively close to the lower radially outer surface of the wedge ring 18. As can be seen in Figure 1, cone axis CA is directed downwardly, to achieve this. Obviously, the force of gravity and the weight of any inserted pipe will tend to maintain contact between the radially outer surface of the wedue ring 18 and the radially inner surface of the mouth 6 in the bottom region. The consequence of these factors is that, upon axial insertion of the wedge ring 0 1 11 18 into the mouth 6, there is a tendency for the radially inner tubular surface of the wed.e ring 18 to move gradually closer to the primary longitudinal axis AX of the 0 C1 0 coupling in the top region, whilst maintaining a generally constant difference in a Z bottom realon. This enables thejoint to accommodate and secure pipes of differing 0 0 diameters, yet maintain a relatively uninterrupted flow surface.

Of course, the wedge ring 18 is contracting all around its circumference. However, the rate at which the radially inner surface moves towards the primary coupling axis as the ring 18 is inserted into the mouth will range from a maximum at the top of the ring, throu-h to a minimum at the bottom.

0 It should be noted that the wedge ring contracts radially about the cone axis CA, rather than radially about the coupling axis AX. To take account of this, the radially inner surface of the bottom portion of the wedge ring actually tapers outwardly in the axially outward direction when in its uncontracted conduction. Furthermore, the wedge ring 18 is seated in a seating portion 21 of relatively greater diameter than the central body portion 10. A generally axially outwardly facing shoulder 23 defines the boundary between the seating portion 21 and the central tubular portion 10. This arrangement means that, as the upper part of the wedge ring 18 is inserted axially into the mouth, there is a tendency for the wedge ring to pivot about the shoulder 23, which axially restrains the bottom portion of the wedge ring 18. This resistance and the flared profile of the bottom radially inner surface of the grab wedge 18 together tend to cause the radially inner surface of the bottom portion of the wedge ring 18 to assume an alignment substantially parallel with the primary longitudinal axis of the coupling as it contracts.

The wedge ring 18 also includes an annular, radially extending projection 22 which cooperates with a sealing ring 24 which will be described in more detail below.

Figure 3 shows a slightly different embodiment. The primary difference between the' 0 embodiments of Figures 1 and 3) is in the central tubular section 10. In the embodiment 12 of Figure 33 this is defined by the profile of the coupling wall itself, which also defines a channel 21 corresponding to the seating portion 21 of Figure 1. This channel 21 performs the same function as seating portion 21, but also resists axial movement of the wedge ring 18 in the axially outward direction. Conversely, the central tubular section 10 of Figure 1 is, in the bottom portion, defined by a moulded radially inwardly projecting step which extends for part of the way around the circumference of the coupling 01 In Figure 3, it can be seen that the wedge ring 18 includes a recessed channel 26. The recessed channel 26 provides a scat within which a pivot 28 of a clam ping mechanism 30 may sit. The purpose of the clamping mechanism 30 is to urge the wedge ring 18 Z_ 0 axially between the radially inner surface of the coupling piece 2 and the radially outer surface of an inserted length of piping 12.

Although a clamping mechanism 30 is not shown in Figure 1, the wedge ring 18 of that figure may be provided with a similar tool.

Figure 4 shows the coupling of Figure 3) in which pipes 12 have been inserted into the coupling piece 2. It should be understood that both the left and right hand portions of the flaure are showing essentially the same details except for the fact that the pipe 12 on 0 the ri-ht hand side of the figure is of smaller diameter than the pipe 12 on the left hand 0 side of thefigure, 1 Each pipe 12, has been inserted so that the very end of the pipe 12 abuts the central flange 4. Clearly, there is a degree in constrained radial separation between the coupling piece 2 and the smaller pipe 12. In order for that pipe 12 to be coupled to the coupling piece 2 with a fluid-tight seal, the gap between the coupling piece 2 and the pipe 12 is provided with a sealing ring 24. In this example, the sealing ring 24 is joined with the wedge ring 18. Those skilled in the art will appreciate, however, that the sealing ring 24 could be a completely separate item. From the figures, it will be apparent that the separation between the pipe 12 and the coupling piece 2 is always the 13 same in the region where the sealing ring 24 sits. Hence compression will always be the same, so the sealing ring 24 can be relatively small and of relatively low cost.

0 Because the sealing ring 24 is with the wedge ring 18, as the wedge ring is 0 Z> 0 0 moved axially into position between the coupling piece 2 and the pipe 12, the sealing rincr 24 will be pushed into place.

Clamping mechanism 30 includes a lever arm 34 which is journalled to the wedge ring 18 by the pivot 28. By comparing the position of the lever arm 34 of the clamping tool 30 of Figure 3 with the position shown in Figure 4, it can be seen that the arm has been rotated through approximately 180' about the pivot 28. Figure -3 represents the 'open' position in which a pipe is received by the coupling piece 2. Figure 4 represents the c clamped' position, in which the pipe is effectively connected to the coupling for use. Because the pivot 28 is held within the recess channel 26 of the wedge ring 18, rotation of the lever 34 initially causes a cam surface 32 provided on the lever arm 34 to abut a bearing surface 38, which is provided on the coupling body and faces generally axially into the coupling mouth 6. Bearing surface 38 is integrally formed with the body of the coupling piece 2, so, as the lever arm 34 is rotated further, the net result of this action is that the wedge ring 18 will be urged generally axially into the coupling socket. As an alternative, the bearing surface 38 could be firmly attached to the body of the coupling piece, rather than integral with it. Continued rotation of the lever 34 in a clockwise direction when viewing the right hand portion of Figure 4, will cause the cam surface 32 to urge the wedge ring 18 further to the left (as shown by the direction of the arrow) within the body of the wedge ring 18. Although the insertion force generated by the lever arm 34 is generally parallel with primary coupling axis AX due to the frustoconical surface configuration, discussed above, the centre of the wedge ring 18 will move along a path which is parallel to cone axis CA. During the course of the insertion, the effect of the radially outer surface of the wedge ring 18 bearing against the radially inner surface of the coupling mouth is that the wedge ring 18 is radially compressed as the wedge ring moves axially (as described above). Hence, once the wedge ring 18 has been urged between the coupling piece 2 and the pipe 12, then these 14 two are clamped together by the resilient nature of the wedge ring and due to the fact that the cam surface 32 of the lever arm 34 abuts the bearina surface 38.

0 Referrin. now to the left hand portion of Figure 4, it can be seen that a pipe 12 of larger diameter than that of the right hand portion of this figure has similarly been clamped into position by using the same process of operating a lever 34, although this time in an anti-clockwise direction. Due to the differing diameters of the pipes, the amount of axial travel which each wedge ring 18 undertakes before clamping the coupling piece 2 to the pipe 12 is different. Clearly, in the right hand portion of this figure the wedge ring 18 has travelled further than that of the left hand portion. This can be seen by reference to the relative positions of both the sealing rings 24 and wedge rings 18 relative to the socket mouths 6.

Referring to Figure 5, which shows a view from above the coupling piece 2 in the open position of Figure 3 it can be seen that each pivot 28 is formed as a connecting member 1 between a pair of flanks, which together define the cam surface 32. The cam surface 32 could, instead, be a single, solid body. The illustrated construction has the advantage of requiring less material to manufacture it, whilst providing sufficient strength.

From the foregoing it will be appreciated that by employing a radially deformable wedge ring 18, the ability to clamp pipes of differing diameters within the coupling piece 2 is obtained. It will also be understood that, by having the described configuration, the grab wedge serves to urge the pipe 12 into an eccentric conjunction with the coupling 12 when the wedge ring 18 is clamped down. This eccentric relationship automatically aligns the lower surfaces of the coupling and the pipes, so as to provide a substantially level flow surface, for the whole range of pipe diameters. Figures 6 to 8 show a further embodiment of the invention.

is It can be seen from these figures that the lever arm 34 is now provided with a channel 40. The pivot 28 is situated within the channel 40 and is able to move along it. The details of these features can be seen most clearly in Figures 12(b) and 13 to 15(c).

The pivot 28 in this embodiment is defined by an elongate pivot member 50. The part of the pivot member 52 that is housed within the channel 40 has a square cross-section. This could, however, be rectangular if preferred. One surface of the channel 54 is provided with a series of ridges. This can be seen most clearly in Figure 15. The square-section part of the pivot member 50 is provided with a pair of corresponding teeth 58 for engaging with the ridged surface 54. More or fewer teeth could be provided, if preferred. The pivot member 50 is provided with an elongate slot 56 which extends into the pivot member 50 in a direction parallel to the channel 40. The slot 56 essentially divides the pivot into two portions 50a, 50b which can be compressed together. This configuration allows the portion 50b of the pivot member 54 that is provided with the teeth 58 to be deflected over the ridges if the pivot bar 50 is moved along the slot. In practice, a specific force must be applied to the pivot bar 50 to deflect it to the extent that each tooth can move over a ridge. Hence, this mechanism essentially locks the position of the pivot bar 50 within the channel until such a force is applied, when the pivot will begin to translate relative to the channel 40.

In Ficlure 6 it can be seen that the mechanism 30 is arranged with the lever arm 34 in a 0 position such that no force is applied to the wedge ring 18 to cause it to move to the right and thereby cause any radial contraction of the wedge ring 18. This is because the lever arm 34 is oriented in a position such that the cam surface 32 does not abut bearing surface 38 and so there is no net force acting on the wedge ring 18 via the pivot 28. Indeed this is the "open position" wherein a pipe shown in outline as 12 may be pushed into position within the coupling piece 2.

Referring now to Figure 7, it can be seen that, once the pipe 12 is in position and 0 housed within the central tubular portion 10, anti-clockwise rotation of the lever 34 about the pivot 28 causes the cam surface 32 to bear acrainst the bearing surface 38 and 16 urge the wedge ring 18 axially, due to the net force acting via pivot member 50, the channel 26, the teeth 52 and the ridges 54. As in previous embodiments, this causes the radially outer surface of the grab wedge 18 to abut the radially inner surface of the mouth 6 and thus force a radial contraction of the wedge ring 18 so as to apply a clamping force to the pipe 12.

c It will be apparent that, at some point during the travel of the lever 34 in its anticlockwise sense, a sufficient load will be applied to the wedge ring 18 and no further force need be applied or indeed should be applied thereto. In fact, in certain cases, damage could be caused if any further force was applied. However, for all but the smallest pipe diameters, arm 3)4 will, at this juncture, still project from the coupling body. Furthermore a fitter would not necessarily be aware of the level of forces being applied to the pipe. The way that this embodiment deals with these problems will be better understood by comparing Figures 7 and 8, Focusing first on Figure 8, it can be seen that continued rotation of the lever 3)4 as between Figure 7 and 8 causes no further force to be applied to the wedge ring 18 in the direction to the right of the figure due to the relative movement which has occurred between the pivot member 50 and the channel 40. Indeed it can be seen that the pivot member 50 has moved from one end of the channel 40 to the other as between Figures and 8. This occurs because the force placed on the lever arm 34 tends to urge the channel to slide over the pivot member 50 and part of this force is directed perpendicularly away from the ridged surface 54 as a consequence of the saw-toothed profile of the ridges. This force tends to urge the part of the pivot member 50 that addresses the ridges further and further towards the opposite wall of the channel until the edges of the teeth 58 of the pivot member 50 are out of engagement with the grooves between the ridges, at which point the ridges no longer resist the movement of the teeth and hence the pivot member 50 through the channel, so the pivot member 50 can move along the channel slightly. Further relative movement of the pivot member 50 through the channel 40 is resisted, because the pivot member is made from a resilient material and the portion 50b provided with the teeth 58 will initially spring back, 7 17 causing the teeth 58 to engage with the ridges again. This effectively locks the relative positions of the pivot member 50 and the channel 40 and, if the force is removed from the lever arm 34, it will stay in its current rotational position. As further rotational force is applied to the lever, however, each tooth 58 will slip over the next ridge in a similar fashion. This process effectively controls the amount of force that is applied to the wedge ring 18 on continued rotation of the lever 34 in an anti-clockwise direction. In this way, therefore, a controlled application force against the wedge ring may be achieved. This, in turn, means that no over-tightening may occur and therefore damage to the pipe 12 or the coupling piece 2 is avoided.

In Fi res 9 and 10 there is shown the coupling of Figures 6 to 8 used with a pipe 42 of gu smaller diameter than that of pipe 12.

It should be noted from Figure 10 that the pivot 28 is still close to the very right hand side of channel 40 - which is different from Figure 8, in which the pivot 28 ends up towards the left-hand side of the channel 40. The reason for this is that, in the arrangement of Figure 8, the wedge ring 18 only contracts a relatively small distance before its radially inner surface meets the radially outer surface of the pipe. Consequently, there is a relatively large distance remaining for the lever to travel before it reaches the closed position in Figure 9. The additional force applied in turning the lever arm 34 causes the channel 40 to move a relatively large distance relative to the pivot member 50 in order to absorb the extra applied force, whilst maintaining the clamping relationship. In the arrangement of Figure 10, where the pipe 42 has a relatively smaller diameter than the pipe 12 of Figure 8, the wedge ring 18 compresses further before it meets any resistance to that compression from the pipe. Consequently, the lever ')4 travels further towards the clamped position and, hence, there is relatively little additional force to be absorbed by translating the channel 40 relative to the pivot member 50. Because a predetermined force is required to begin translation of the channel relative to the pivot member, the pipes 42 and 15 are each clamped by the wedge ring 18, with substantially the same clamping force.

18 Figure 12(a) schematically shows a perspective view of an alternative form of pivot member 50 and lever arm 54. In Figure 12(a) there is shown a lever arm 30 having a pair of flanks, each provided with a rectangular channel 40 within which the pivot bar 50 extends. The pivot bar 50 comprises a cylindrical portion 51 coupled at either end to a parallelepiped, here cuboid 52. The outer peripheral shape of each cuboid 52 is such as to be able to slide within the channel 40, without twisting. The cylindrical portion is journalled with the wedge ring 18 and rotates within channel 26.

Referring again to Figure 12(b) it can be seen that the roles of the cylindrical portion 51 and cubolds 52 of Figure 12(a) have been reversed, such that the pivot bar 50 comprises a central cuboid 52 flanked at either end by cylindrical portions 5 1. The cylindrical portions 5 1 are j ournalled with the wedge ring.

0 Figure 13 shows the arm 34 and pivot bar 50 of Figure 12(b) in more detail. It can be seen from Figure 13(a), which shows such a tool in perspective view and Figure 13(b), which shows a section alona the line AA of Figure 13(a), that the channel 40 is formed to have a plurality of ridges 54 along one surface thereof. The cuboid portion 52 of the pivot 28 is provided with co-operative teeth 58. In this way, therefore, the cooperation between the teeth and serrations 54 acts as a ratchet mechanism as described above.

Figure 11 shows an alternative form of clamping mechanism to that of all previous figures. In Figure 11 (a) it can be seen that the clamping member used to exert a clamping force against the wedge ring 18 comprises an annular member 46 having a raised, or ramped, surface 48. The ramped surface 48 stands proud of the remainder of the surface of the annular member 48. Before insertion of a pipe the components are arranged generally as shown in Figure 1 1(b), then, once it is desired to exert the necessary force against the wedge ring 18 to cause it to clamp the pipe in place, all that is required is for the user to cause rotation of the member 46 in the direction shown by the arrow in Figure 11 about the axis 47. This causes the ramp surface 48 to exert an axial force against the wedge ring 18 - thereby urging it Into its locked or clamped position. This is shown schematically in Figure 1 1(b).

19 Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments which are given by way of example only and which are not intended to limit the scope of the invention - that being determined by the appended claims.

For example if the wedge ring 18 was alternatively to sit on the outside of a pipe as opposed to the inside of the pipe engagement member, and if the outside of the pipe was flared, then the wedge ring 18 may need to radially expand in order to provide a sufficient clamping force between the pipe and the pipe connecting member. Those skilled in the art will appreciate it is simply a matter of design choice as to whether the wedge ring 18 is of the expansion or contraction type. In the examples used herein, however, only a radially-contractible wedge ring 18 has been described in detail.

Furthermore, although the lever arm is shown as fixed to the wed e ring 18 and bearing g against the socket, this could be reversed.

1

Claims (1)

1. CLAIMS:

   1. A pipe joint comprising: a socket for receiving a pipe member; and a radially deformable member for insertion between a radially inner surface of the socket and a radially outer surface of the pipe member, wherein the radially deformable member is adapted to maintain radial separation of the radially inner surface of the socket and the radially outer surface of the pipe member in a first circumferential re-ion of the socket, and maintain radial proximity between the radially inner surface of the socket and the radially outer surface of the pipe member in second circumferential region of the socket.

   0 2. A pipe joint according to claim 1, wherein the radially deformable member is defined by a ring having a varying radial thickness around its circumference.

   3. A pipe joint according to claim 2, wherein the radial thickness of the radially deformable member increases for 180' about its circumference, then decreases for about 180' about its circumference starting from a point of minimum thickness.

   4. A pipe joint according to either claim 2 or claim J3), wherein the radially deformable member has the general form of a discontinuous ring.

   5. A pipe joint according to any one of claims 1 to 4, wherein the socket comprises a frustoconical radially inner surface and the radially deformable member comprises a generally corresponding frustoconical radially outer surface for bearing against the frustoconical radially inner surface of the said socket in such a manner as to cause it's radial contraction upon axial displacement of the radially deformable member relative to the said socket.

   21 6. A pipe joint according to claim 5, wherein a radially inner surface of the said radially deformable member is tubular and its longitudinal axis is not parallel to the axis of the said frustoconical surface of the radially deformable member.

   7. A pipe joint accordina to claim 6, wherein the axis of the frustoconical surface p is inclined downwardly in the axial direction, when the joint is in use.

   8. A pipe joint according to any one of the preceding claims, wherein the said radial proximity is such that axially extending portions of an inner circumference of both the socket and the pipe lie substantially flush with each other when the two are joined together.

   9. A pipe joint according to claim 8, wherein the said second circumferential region of the said socket comprises an at least partannular axial region having a 0 relatively greater radius than another axial region, situated in the same circumferential region, for accommodating at least part of the said radially deformable member.

   10. A pipe joint according to any one of the preceding claims, the joint further includes means for axially urging the radially deformable member between the axially inner surface of the socket and the axially outer surface of pipe, so as to cause radial contraction of the radially deformable member.

   11. A pipe joint according to claim 10, wherein the means for urging the radially deformable member comprises a generally circular ring having a portion of an axially facing surface raised with respect to the remainder of that surface and the said radially deformable member comprises an inclined, generally axially facing bearing surface which addresses the said axially facing surface of the circular ring; wherein rotation of the ring causes the raised surface.thereof to move over the bearing surface so as cause axial movement of the radially deformable member.

   22 12, A pipe joint according to claim 10, wherein the means for urging the radially deformable member comprises an arm which is pivotally connected to one of the radially deformable member and the socket about a pivot axis perpendicular to the axial direction and comprises a cam surface for bearing against a generally axially inwardly facing bearing surface provided on the other of the radially deformable member the socket, such that rotating the arm about the pivot axis brings the cam surface to bear against the said bearing surface and continued rotation of the arm about the pivot urges the radially deformable member axially further into the socket.

   13. A pipe joint according to claim 12, wherein the bearing surface is provided on the socket and faces generally axially inwardly.

   14. A pipe joint according to claim 12 or 13, wherein one of the socket and a pipe to be coupled includes a location member for the lever.

   15. A pipe joint according to any preceding claim, wherein the radially deformable member maintains the socket and the pipe member clamped in an eccentric relationship.

   16. A pipe joint according to any one of the preceding claims, wherein the radial proximity between the socket and the pipe member is situated in a lower region thereof- 17. A pipe joint according to any one of the preceding claims, further comprising a rina seal situated radially intermediate the socket and the pipe member.

   0 18. A pipe joint according to claim 17, wherein the ring seal abuts the radially deformable member, 19. A pipe joint according to claim 17, wherein the ring seal is joined with the radially deformable member.

   23 20. A radially deformable member for a pipe coupling, having a radial thickness that increases for 180' about its circumference, then decreases for 180' about its circumference starting from a point of minimum thickness.

   21. A radially deformable member according to claim 20, wherein the radially deformable member is generally ring-shaped.

   1 0 22, A radially deformable member according to claim 21, wherein the ring is discontinuous.

   23. A radially deformable member according to any one of claims 20 to 22 comprising a frustoconical radially outer surface.

   24. A clamping. mechanism comprising a first body and a second body to be moved in a first direction relative to the first body and secured in a clamped relationship therewith; wherein the mechanism further comprises an arm and a pivot, the said arm being journalled to the first body by the said pivot, the pivot axis being generally perpendicular to the said first direction, and one of the arm and fixst body being translatable relative to the pivot axis, or vice versa, in a plane perpendicular to the pivot axis and the other of the arm and the said first body not being translatable relative to the said pivot axis in the said plane; the second body comprises a bearing surface facing generally in the said first direction; the said arm comprises a cam surface for bearing against the said bearing surface when the arm is rotated about the pivot; and resistance means is provided for resisting the said relative translation between the pivot axis relative to the said one of the arm and first body; the arrangement being such that rotation of the arm from a non-clampin.a position towards a clamping position causes the cam surface to bear against the bearing surface, which initially urges the first body in the first direction until a predetermined 24 resistive force is experienced, after which further rotation of the arm causes relative translation between the pivot and to the said one of the arm and the first body, reversal of the said translation being resisted by resistance means, which thereby serves to secure the rotational portion of the arm when the applied rotational force is released.

   25. A clamping mechanism according to claim 24, wherein the pivot is movably housed within a channel provided in the arm or the first body in order to enable the said translation to occur.

   26. A clamping mechanism according to claim 24, wherein the said resistance 0 means is a ratchet mechanism housed within the channel.

   27. A clamping mechanism according to claim 26, wherein the channel is provided with a series of ridges and a portion of the pivot located within the channel is provided with a resiliently projecting dog which can move across the ridges when a predetermined turning force is applied to the arm, but locates behind one of the ridges to resist reversal of the said translation when the turning force is removed.

   28. A pipe joint according to Claim 12 or any claim dependent thereon, wherein the means for urging the radially deformable member is a clamp mechanism according to any one of Claims 24 to 27, the said radially deformable member defining the said first body and the said socket defining the said second body.

   29. A pipe joint substantially as hereiribefore described, with reference to the accompanying drawings.

   30. A radially deformable member substantially as hereinbefore described, and reference to the accompanying drawings.

   31. A clamping mechanism substantially as hereinbefore described, with reference to the accompanying drawings.