Pipe coupling

Abstract

A tube coupling comprises a coupling body (1) having an open-ended through passage for receiving a tube (T). A collet (41) is located in the open end of the through passage having a ring (52) and a plurality of flexible arms (53) extending generally axially from the ring into the through passage. The through passage has a tapered surface (43) converging toward the open end, and the collet arms have heads at their distal ends for engaging both the tapered surface and a tube extending through the collet into the through passage to be compressed against the tube by the tapered surface with outward movement of the collet relative to the through passage to secure the tube in the through passage. A collet lock is formed on the collet (41) having a locked rotational position in which the lock retains the collet in the outward tube securing position and an unlocked rotational position in which the collet is movable axially relative to the through passage to release and engage the tube through the collet. One of the body (1) and the collet (41) is provided with a cam surface (46) and the other is provided with a cam follower (56), the cam surface being arranged to provide a locked position and an unlocked position. The invention also extends to the collet (41).

Description

Technical Field

[0001] The present invention relates to a pipe coupling. The pipe coupling has particular application as a fiber optic cable connector for use above or below ground. However, the concept is more broadly applicable to other types of connectors. Background Art

[0002] Such fibre optic cable connectors are used in the laying of fibre optic cables.The cables are used, for example, for providing a fibre optic cable connection from a junction box to a building such as an office or a residence in order to provide a connection for Internet data.

[0003] Fiber optic cables are provided in bundles of individual fibers that can be several kilometers long. The fiber bundles are loaded through tubes (often called microducts) that are typically 100 meters long, but can be up to 500 meters long. Therefore, multiple tubes need to be connected together in order to support the complete length of the fiber bundle.

[0004] Because of the way they are used, there are many requirements placed on fiber optic cable connectors.

[0005] Its outer diameter must be as small as possible to minimize volume, since connectors are often grouped together in large numbers.

[0006] Connectors also need to be highly impact-resistant. Cables are often buried underground, and for maintenance, they need to be dug out. This is usually done by workers with shovels, and the first time a worker knows whether a cable is present is when it is hit by the shovel. Therefore, connectors need to be robust enough to resist such impacts. In practice, they need to pass a "15J impact test".

[0007] The connector has a connection at each end which attaches to the tube and holds the tube within the connector. This is done using a collet or snap ring. It grips on the outer wall of the tube, and any movement tending to pull the tube out of the connector causes the collet to tighten its grip on the tube in a well-known manner. To release the tube, the collet can be manually displaced toward the interior of the connector. This prevents the collet from gripping the tube, allowing the tube to be withdrawn from the connector.

[0008] A requirement of fiber optic cable connectors is that the collet must be locked in place to prevent accidental release of the tube.

[0009] This is conventionally accomplished using a locking clip that is clamped between the end of the body of the connector and the collet ring, thereby preventing axial movement between the body and the collet.

[0010] These clips have a number of disadvantages. They are fragile and exposed components and often break. Because they are exposed, they can become clogged with dirt, which makes them potentially difficult to remove. During installation, they can accidentally become dislodged and can then be easily lost, rendering the connector unusable unless a spare clip is carried. Clips can then also become dislodged during installation. The installer will not necessarily know that this has occurred, as this may only occur if the connector is covered in mud. Summary of the invention

[0011] The present invention aims to address at least some of these problems.

[0012] An alternative method of locking a collet within a connector is disclosed in our own earlier EP2131089. This invention discloses the concept of a locking ring rotatably mounted on a body. The body is provided with a cam surface which cooperates with a cam follower on the locking ring. Rotation between the body and the locking ring changes the axial spacing between the two components. The end of the locking ring abuts against the collet ring. In the locked position, the axial spacing between the locking ring and the body is at its maximum. The engagement between the locking ring and the collet ring prevents axial movement of the collet so that the collet cannot be displaced inwardly to a position where the tube can be released.

[0013] This connector is not designed for use with fiber optic cable connectors, and in fact, it is not suitable for such a purpose. The locking ring is mounted on the outer surface of the body. This increases the size of the connector, which runs counter to the requirement that the outer diameter of the fiber optic cable connector be as small as possible. The locking ring is exposed to dirt, so that during use, dirt particles may enter the locking ring and jam the locking ring in the locked position. In addition, the locking ring may also be damaged during installation and maintenance operations, which may cause the locking ring to fail, or become stuck in the locked position.

[0014] According to the present invention, a pipe coupling according to claim 1 is provided.

[0015] With the present invention, locking of the collet is now achieved solely by the interaction between the body and the collet. This eliminates the locking clip of the prior art. It also eliminates the locking ring of EP2131089.

[0016] Although the present invention is motivated by the need to provide an improved fibre optic cable connector, because it provides improvements over EP 2 131 089 in terms of the low profile nature of the connector and the reduction in the number of parts (because it does not require a locking ring), it can also be used in any environment that EP 2 131 089 was designed for. In particular, it is suitable for use in a wide range of plumbing applications providing fluid connectivity.

[0017] Because locking is accomplished by the interaction between the body and the collet, the locking mechanism can actually be inside the body. This can provide a low profile design and also protect the locking mechanism from impact damage and from dirt ingress.

[0018] The cam surface may be provided on the body or on the collet, but is preferably provided on the body. In this case, the cam surface may be molded directly into the body as part of the body molding process. However, this requires relatively complex tooling. Therefore, preferably, the body comprises a cap held by the main body part, the cap being provided with the cam surface. The cap may be fitted over or in the main body part. It may be held by teeth gripping the main body part, ultrasonic welding, snap fit, threaded fit or in any other way.

[0019] With prior art fiber optic cable connectors, it was necessary for the collet to protrude beyond the body to allow for an annular gap in which the locking clip is inserted. This is not necessary in the present invention. The collet ring may still protrude axially beyond the body, but preferably, in the locked position, the collet ring does not protrude axially beyond the body. It may be flush with the body, but is more preferably recessed into the body. This protects the collet ring from impact damage and from dirt.

[0020] The collet ring may be a conventional annular collet ring which a user grasps in order to rotate the collet between a locked position and an unlocked position. However, preferably an unlocking feature is provided in the collet ring. This may take the form of one or more openings in the axial end face of the collet ring. However, these require the use of tools and may become clogged with dirt.

[0021] Therefore, preferably, at least one lug projects from the collet ring axially away from the open end of the through-passage.This provides a tip at which the collet can be easily grasped for rotation.

[0022] The lug or each lug may not extend axially beyond the body. However, the lug or each lug preferably extends axially beyond the end of the body. This makes it easier to grip them. In addition, the lugs may provide a burr removal function. For example, they may be shaped to have an abrupt edge so that the lug can be inserted into the cut end of the tube and scraped around the inner edge to remove any burrs left by the tufting process. During use, these may create a snagging hazard, so it will be very useful for the operator to have a tool at hand to remove these burrs in practice.

[0023] There may be a single lug. However, preferably there are two or more spaced apart lugs as this provides an improved grip and also allows the gripping function to be maintained if one of the lugs is damaged. As stated above, it is preferred that the collet ring does not protrude axially beyond the body. The or each lug preferably protrudes beyond the axial end of the body so that it can be easily gripped.

[0024] At least one of the body and / or the collet is preferably provided with a visual indication of the locked position and / or the unlocked position.

[0025] Near the locked position, the cam surface is preferably provided with a raised block that the cam follower will pass over. This is used to ensure that the cam follower remains in the locked position and also provides a tactile indication to the user that the locked position has been reached.

[0026] When the coupling is used as a pipe connector, the connector body is preferably made of a non-opaque plastic.

[0027] In addition, the body preferably includes an outer sleeve and an inner sleeve, the inner sleeve being configured to receive the distal end of the corresponding tube, the outer wall of the inner sleeve being generally spaced apart from the inner wall of the outer sleeve to define a gap, the inner sleeve being supported on the outer sleeve by a discrete web of material that supports the inner sleeve and maintains the gap between the inner sleeve and the outer sleeve. This provides an impact protection feature because the gap allows any impact to the outer sleeve to deform the outer sleeve, which will deform into the gap before the impact deforms the inner sleeve.

[0028] Preferably, the connector has no external ribs and has a continuous outer surface with a constant radius. This eliminates the ribs provided on prior art connectors, which however also provide stress concentrations and areas where dirt can accumulate.

[0029] Preferably, the annular flange extends radially into the through passage, each end face of the annular flange providing a stop surface for a respective tube end, wherein the annular flange is undercut such that its end faces are inclined such that the axial dimension of the flange increases towards the axis. Such undercutting ensures that the inner edge of the tube can come closer to the annular flange and preferably abuts the annular flange. This eliminates or minimizes the possibility of fibers (which subsequently pass through the connector once the tube is in place) catching on the tube or the annular flange.

[0030] Preferably, a plurality of annular splines are provided near the annular flange to deflect the outer wall of the tube as it approaches the flange. In practice, the tube is supplied on coils and is often already flattened to an oval cross section. In the region where the oval is widest, the inner diameter is larger than it would otherwise be, and this exposes part of the annular flange in this region. This presents a risk of snagging of the fibers, which is significantly reduced by the use of splines. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Examples of connectors according to the present invention will now be described with reference to the accompanying drawings, in which:

[0032] Figures 1A to 1C is a cutaway perspective view of the connector showing the progressive insertion of the tube;

[0033] Figure 2A It is the main passage of the connector body in a plane perpendicular to the connector body and passing through Figure 2B A cross-sectional view of line AA in FIG.

[0034] Figure 2B The connector body is in a plane passing through the main axis of the body and passing through Figure 2A A cross-sectional view of line BB in FIG.

[0035] Figure 2C is with Figure 2A A view of a second example of a connector is shown in the same plane;

[0036] Figure 2D is with Figure 2B A view of a second example is shown in the same plane;

[0037] Figure 3 The connector is Figure 2B A cross section in a plane of , wherein the tubes are connected and through which the fiber bundle passes;

[0038] Figure 3A Shown in more detail Figure 3 The central part of

[0039] Figure 3B Shows something like Figure 3A , which has a different tube configuration and no fibers passing through;

[0040] Figure 4A and Figure 4B Corresponds to Figure 3A and Figure 3B , showing the prior art arrangement;

[0041] Figure 5 is an exploded perspective view of the connector as viewed from one end of the connector body;

[0042] Fig. 6A yes Figure 5 An equivalent in non-exploded form of , showing the cartridge and collet in a first angled configuration;

[0043] Figure 6B It passes through Fig. 6A A cross section through a plane of the locking projection;

[0044] Fig. 7A and Figure 7B is corresponding to Fig. 6A and Figure 6B , showing the cartridge and the collet in a second angled configuration, respectively; and

[0045] Fig. 8A and Figure 8B Corresponds to Fig. 7A and Figure 7B , but showing the tube in situ. DETAILED DESCRIPTION

[0046] The connector comprises a connector body 1 having a generally hollow cylindrical configuration centred on a main axis X. A connector 2 (described in more detail below) is provided at each end to receive and grip a tube T sealed by an O-ring 3 at each end.

[0047] The body 1 is molded from a non-opaque plastic. The plastic must be sufficiently transparent so that an external visual inspection of the connector allows the operator to determine whether there is a fiber or fiber bundle F at the center of the connector. Ideally, the body should be as close to transparent as possible. However, practical considerations mean that the body will not be completely transparent. Instead, the body may be translucent to the extent that the fibers are visible enough. Suitable materials are polycarbonate, polystyrene, polyester, acrylic fiber and nylon. The body 1 is formed during the molding process and can optionally be polished to improve the light transmission of the body. As can be seen from the multiple figures, the outer profile of the body is a smooth construction, which has no external ribs, thereby eliminating any stress concentration and dirt accumulation orifices.

[0048] The body 1 is composed of an outer sleeve 5 and an inner sleeve 6 which are connected by at least one web 7 as described below.

[0049] The outer sleeve 5 has an axial bore 8 which is open at a distal end 8 and has a first step 10 and a second step 11 which receive the connector 2 as described below.

[0050] The inner sleeve 6 is held by the web 7 so as to form a gap 12 having a substantially uniform thickness, as in Figure 2A As best seen in .

[0051] If from Figure 2A and Figure 2B As will be appreciated, the web 7 extends across only a small portion of the inner sleeve 6 , such that the gap 12 exists over most of the length and circumference of the inner sleeve 6 .

[0052] Any impacts that occur to the outer sleeve 5 during the installation of the pipeline or when the pipeline is dug out for maintenance may cause deformation of the outer sleeve 5 .

[0053] By providing the gap 12, the effect of any external impact on the outer sleeve 5 is isolated from the inner sleeve 6 to a significant extent, and thus prevents to a large extent any change in the diameter of the inner bore 14 of the inner sleeve 6. Preliminary tests have shown that this design is effective in resisting external impacts. In addition, this can be achieved in a way that does not require the addition of ribs and does not require an increase in the outer diameter of the connector.

[0054] The use of a very small size web 7 means that the chance of a shock being transmitted directly from the outer sleeve 5 to the inner sleeve 6 via the web 7 is greatly reduced. Even if this happens (i.e., Figure 2A In the vertical downward direction Figure 2B The inner sleeve 6 can still deflect by an amount equal to the width of the gap 12 before any stress is generated on the inner sleeve (which would adversely affect the inner hole 14 of the inner sleeve 6).

[0055] In order to mould the body 1, all the plastic required for the inner sleeve 6 needs to pass through the webs 7, 15. This represents a fairly significant amount of plastic flowing into a relatively complex and narrow flow path. To alleviate this, we envisage providing Figure 2A One or more additional webs 13 schematically depicted in the figure are angularly offset relative to the web 7 and may also be offset axially to ensure that there is no point at which the inner sleeve 6 is supported on diametrically opposite sides. The additional webs 13 provide a further flow path for the plastic to enter the inner sleeve during the molding process. Multiple webs can be made weaker than a single web so that the web closest to the impact breaks preferentially under the applied load, leaving the remaining ribs to support the inner sleeve 6.

[0056] With Figure 2A In contrast to extending in the radial sense as shown in FIG. 1 , the web 15 or each web 15 may be as shown in FIG. Figure 2C 12, or in any other direction across the gap 12. Figure 2D As shown in FIG. 1 , the webs 15 are axially offset relative to the annular flange 20 so that they do not impair the visibility of this region.

[0057] Now refer to Figure 3 , Figure 3A and Figure 3B To describe the way in which the connector is constructed to avoid hooking of the fiber F, Figure 4A and Figure 4B Used to provide a comparison with the prior art.

[0058] Figure 3A connector body 1 is shown with a tube T secured and sealed at each end. Once connected in this manner, a fiber F is blown from one end through the tube T, across the joint between the tubes, and into the adjacent tube.

[0059] The tube T abuts against the annular flange 20 at the midpoint of the inner sleeve 6. The connector 2 and the O-ring 3 have substantially the same inner diameter as the inner diameter of the inner sleeve 6, so that when the tube T is pushed into the body 1, it is guided into the inner sleeve 6. The end of the tube T then abuts against the annular flange 20. As in Figure 3A and 3B As can be best seen in FIG. 2 , the annular flange 20 is provided with an undercut portion 21 such that the thickness of the annular flange 20 in the axial direction increases towards the axis X.

[0060] Therefore, the innermost corner 22 of the tube T is the first part of the tube T that abuts the annular flange 20. This means that there is no gap between the inner face 23 of the tube T and the annular flange 20.

[0061] As in Figure 3A and Figure 3B As shown in , the undercut portion 21 is rounded. Similarly, the radially innermost corner 24 of the annular flange is rounded to present a smooth surface to the fiber.

[0062] with Figure 4A Compared to the prior art arrangement shown in , the elimination of the gap G between the end of the tube T and the annular flange 20 means that there are no exposed, protruding edges of the tube T upon which the fibers F could get hooked.

[0063] Figure 3B The case where the left-hand tube is cut at a slightly inclined angle to a plane perpendicular to the axis X is depicted. Thus, the uppermost edge 25 of the tube T enters the undercut region 21 and seats on the annular flange 20 .

[0064] Through Figure 4B By comparison, it can be seen that the gap between the tube T and the annular flange 20 is eliminated in the upper half of the figure, and Figure 4B In comparison, the gap at the bottom is significantly reduced.

[0065] If from Figure 3A and Figure 3B As is apparent, the radially inward extent of the annular flange 20 is greater than the inner diameter of the tube T. Thus, the annular flange 20 protrudes slightly inwardly beyond the inner face 23 of the tube T. Figure 3B and Figure 4B If we assume that the fiber F is loaded from right to left, the end of the fiber is near the connector 1 along Figure 3B and Figure 4B The lower part of the inner surface 23 in Figure 3BIn the embodiment of FIG. 1 , the end will first encounter a corner of the annular flange 20 that projects slightly beyond the inner surface 23 of the tube T. However, the fiber F can easily pass over this curved corner, and in doing so, the deflection should push the end of the fiber over the exposed edge 28 of the tube T. In contrast, in FIG. Figure 4B In the embodiment, the annular projection S does not protrude beyond the inner surface 23 of the tube, so there is nothing to start deflecting the fibers F back toward the center of the hole. In addition, Figure 4B The gap G' in Figure 3B Thus, not only will the fiber not be deflected away from the gap, the presence of the large gap provides a significantly greater opportunity for the fiber to enter the gap and hook onto the edge 28 of the tube T.

[0066] A further feature to prevent snagging of the tube is the listed splined arrangement, as best shown in FIGS. 1 and 2 .

[0067] As can be seen from these figures, six axially extending splines 30 are equally spaced around the circumference of the inner sleeve 6. These are shown as having a constant cross section in a plane perpendicular to the axis. However, they may have a thickness that increases towards the annular flange 20.

[0068] As in Figure 1A and Figure 1B As shown in FIG, the tube T from the coil has been filled and has assumed a flattened oval shape. When the tube T enters the inner sleeve 6, the tube T engages with the enlarged portion of the tube T and tends to push the tube T back as in FIG. Figure 1C A more rounded shape as shown in .

[0069] Any number of splines may be used. However, six is ​​considered a reasonable number. This allows engagement with flat tubes inserted in any orientation. A smaller number of flanges carries the risk that an enlarged portion of the tube may enter between adjacent splines. On the other hand, adding more splines increases the insertion resistance of the tube T into the connector 1.

[0070] The splines 30 are sized so that where they exist they are slightly smaller than the outer diameter of the tube. Therefore, the splines 30 will bite into the material of the tube T in these areas. This ensures a secure and robust fit of the tube T and also provides the greatest opportunity for the splines to reduce eccentricity of the tube.

[0071] Now refer to Figure 5 The connectors 2 (one at each end of the body 1 ) are described in more detail in FIG. 8 .

[0072] The connector 2 is formed of two parts, namely, a holder 40 and a collet 41 .

[0073] The card seat 40 has a generally annular configuration. The outer surface is provided with a plurality of flexible metal teeth 42. The card seat 40 is inserted into the end of the body 1 until it is seated against the second step 11. The teeth 42 grip the wall of the body 1 to ensure that the card seat 40 is permanently retained in the body 1. At the end of the card seat 40 adjacent to the second step 11, there is a tapered cam surface 43, which cooperates with the collet as described below. At the opposite end, the end face of the card seat 40 is provided with a pair of ramp surfaces 44. Although two such surfaces are shown, there may be a single surface or there may be more than two surfaces. Each ramp surface has a low point 45 corresponding to the unlocking configuration and a high point 46 corresponding to the locking configuration in the middle inclined surface 47. A raised block 48 is provided at the junction between the high point 46 and the inclined surface 47. A similar raised block may be provided at the junction between the inclined surface 47 and the low point 45. The low point 45 terminates at a first end stop 49 and the high point 46 terminates at a second end stop 50 .

[0074] Most features of the collet 41 are conventional. It has a collet ring 52 from which a plurality of flexible arms 53 extend. Each arm has a head 54 at its distal end and is provided with inwardly projecting metal teeth 55.

[0075] In the case where the tube T is inserted (e.g., as in Figure 8B ), any movement tending to pull the tube T out of the connector causes the teeth 55 to grip into the tube, which pulls the head 54 toward the tapered cam surface 43 on the cartridge 40 which deflects the arms 53 inwardly to provide a gradually increasing gripping force on the tube T. This force serves to hold the tube T securely in place. This is the conventional manner in which the collet operates.

[0076] An improvement provided by the present invention is the presence of a pair of cam followers 56 extending from the collet ring 52 toward the ramp surface 44 on the cassette 40. Although two followers 56 are shown, there are actually as many followers 56 as ramp surfaces 44. Alternatively, the cam arrangement could be reversed so that the ramp surface(s) are on the collet and the follower(s) are on the cassette.

[0077] The collet ring 52 is also provided with a pair of projections 57 extending from the collet ring 52 in a direction opposite to the followers 56. As shown in the drawings, the positions of the projections 57 correspond to the number and position of the followers 56. However, this may not be the case. The components may be offset relative to each other, and the number of both need not be the same.

[0078] The operation of the collet will now be described with reference to Figures 6 to 8. Fig. 6A and Figure 6BThe position shown in is the unlocked position. In this position, the pawl 41 has been rotated so that the cam follower 56 abuts the first end stop 49 so that the cam follower is at the low point 45. Figure 6B (especially when Figure 7B As is apparent from the comparison, in this position, the collet 41 has a relatively large axial freedom, since it can move from the position where the head 54 engages the conical cam surface 43 all the way to the left to the position shown in the figure (see FIG. Figure 6B If held in this position by the user, the tube T can be withdrawn because the head 54 is held away from the tapered inclined surface 43 so that the collet cannot grip the tube. The collet 41 is then rotated in the direction of arrow 60 to the position in which the collet is positioned. Fig. 7A In doing so, the follower 56 moves upward along the inclined surface 57, over the raised block 48 (thereby providing the user with a tactile feeling that the position has been reached) to the high point 46.

[0079] If from Figure 6B and Figure 7B As understood from the comparison of Figure 7B In the locked position shown in FIG. 1 , the collet does not have the same Figure 6B The same degree of freedom as in the embodiment of the present invention makes it impossible to be moved and held in the unlocked position in which the tooth 55 is disengaged from the tube T. Fig. 8A and Figure 8B It is more obvious in Fig. 8A and Figure 8B The collet is shown in the Fig. 7A and Figure 7B The same locking position in FIG. 4, but the tube is in place. Here, it can be seen how the presence of the tube pushes the head 54 back onto the conical cam surface 43.

[0080] In this locked configuration, the only way to remove the tube T is for the user to grasp the projection 57 and move the collet 41 in the Fig. 6A The collet is rotated in the direction of arrow 61 in the figure to the unlocked position and the collet is manually held in place while the tube is pulled out of the body 1. Figure 6B The location shown in .

[0081] The tube T is usually inserted with the collet 41. Fig. 6A and Figure 6B The unlocked position shown is preferred because this allows a greater range of deflection of the arm 53 during tube insertion. Figure 7B As can be seen in the figure, even in the locked position, there is a small gap between the head 54 and the tapered cam surface 43. It is therefore possible to insert the tube T with the collet in the locked position. This provides a simple assembly process as the user only needs to be instructed to insert the tube into the collet. They do not need to trouble themselves with the locking operation.

[0082] If available from Figures 1A to 1C and Figure 3 As best seen in Figure 1, the collet ring 52 is arranged to be axially set back inside the body 1. However, the projection 57 extends beyond the end of the body 1. In this position, the collet 41 is protected from external impacts from the body 1. In addition, because it is recessed within the body 1, it is protected to some extent from contact with the soil (in which the cable is buried). With this connector, the only points where dirt can potentially enter the inner working area of ​​the connector are between the collet ring 52 and the tube T and between the collet ring 52 and the body 1. However, these are joints where close tolerances can be applied. Any dirt that enters here will not impair the visibility of the fiber F within the body 1. In addition, due to the rotational action required to unlock the collet, even if some dirt does enter these gaps, it is unlikely to jam the collet 41 because the rotational motion can easily generate sufficient torque to overcome any such jamming.

[0083] The tabs 57 have right angle corners. This allows them to be inserted into the cut end of the tube T and scraped around the inner edge of the tube to remove any burrs that form during the cutting operation and that might otherwise present a snagging hazard to the fibers F. The edges may be shaped in different ways to provide more effective burr removal.

[0084] The connector 2 described above combines an outer sleeve 5 and an inner sleeve 6 supported by a web 7 and an unconventional arrangement of annular flange 20 and splines 30. However, the connector may equally be used in a coupling having a conventional interior without these features.

Claims

1. A pipe coupling, comprising: a coupling body having an open-ended through passage for receiving a tube; a collet located in the open end of the through passage, the collet having a ring and a plurality of flexible arms extending axially from the ring into the through passage, the through passage having a tapered surface converging toward the open end, and the flexible arms having heads at their distal ends for engaging both the tapered surface and a tube extending through the collet into the through passage in use to be compressed against the tube by the tapered surface to secure the tube in the through passage by outward movement of the collet relative to the through passage; and a collet lock integrally formed on the collet, the collet having a locked rotational position in which the collet lock retains the collet in an outward tube securing position and an unlocked rotational position in which the collet is axially movable relative to the through passage to release and engage a tube through the collet; One of the body and the collet is provided with a cam surface, and the other of the body and the collet is provided with a cam follower, wherein the cam surface is configured to provide a locked position and an unlocked position.

2. The coupling according to claim 1, characterized in that: The cam surface is on the body.

3. The coupling according to claim 2, characterized in that: The body includes a cap held by the main body portion, the cap being provided with the cam surface.

4. The coupling according to claim 1, characterized in that: The ring does not protrude axially beyond the body.

5. The coupling according to claim 4, characterized in that: The ring is recessed into the body.

6. The coupling according to claim 1, characterized in that An unlocking feature is provided on the ring.

7. The coupling according to claim 6, characterized in that At least one lug projects from the ring axially away from the open end of the through passage.

8. The coupling according to claim 7, characterized in that The at least one lug protrudes axially beyond the body.

9. The coupling according to claim 8, characterized in that The at least one lug has an abrupt edge.

10. The coupling according to any one of claims 1 to 9, characterized in that: At least one of the body and / or the collet is provided with a visual indication of the locked position and / or the unlocked position.

11. The coupling according to any one of claims 1 to 9, characterized in that: Near the locked position, the cam surface is provided with a raised bump over which the cam follower will ride.

12. The coupling according to any one of claims 1 to 9, characterized in that: The coupling body is made of non-opaque plastic.

13. The coupling according to any one of claims 1 to 9, characterized in that: The body includes an outer sleeve and an inner sleeve, the inner sleeve being configured to receive the distal end of the corresponding tube, the outer wall of the inner sleeve being spaced apart from the inner wall of the outer sleeve to define a gap, the inner sleeve being supported on the outer sleeve by a separate material web, the material web supporting the inner sleeve and maintaining the gap between the inner sleeve and the outer sleeve.

14. The coupling according to any one of claims 1 to 9, characterized in that: The coupler has no external ribs and has a continuous outer surface with a constant radius.

15. The coupling according to any one of claims 1 to 9, characterized in that: An annular flange extends radially into the through-passage, each end face of the annular flange providing a stop surface for a corresponding pipe end, wherein the annular flange is undercut so that its end face is inclined so that the axial dimension of the annular flange increases toward the central axis of the through-passage.

16. The coupling according to claim 15, characterized in that A plurality of annular splines are provided on a wall of the through passage adjacent the annular flange to deflect an outer wall of the tube as the tube approaches the annular flange.

17. A collet for a pipe coupling according to any preceding claim, the head having teeth on a radially innermost face for gripping a pipe in use; The collet is integrally provided with a collet locking feature in the form of a cam feature arranged so that, in use, the depth to which the collet can be inserted into the coupling body will vary with different angular positions of the collet, The cam feature is a cam follower extending from the ring in the direction of the flexible arm.

18. The collet according to claim 17, characterized in that At least one lug provides an unlocking feature, the at least one lug axially extending from the ring in a direction opposite to the direction in which the flexible arms extend.

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