Patent Description:
Such connectors are used routinely in commercial developments such as hotels, schools, offices and the like.

These connectors are inside diameter (ID) connectors such that they have a body which fits inside the pipe and seals on the inner wall of the pipe. This is primarily done because these multi layered pipes have a laminated structure and the pipe may tend to delaminate in the vicinity of a cut end. This cut end would be exposed to the fluid within the pipe if the seal were made with the outer diameter of the pipe. The liquid could cause further separation of the layers and ultimately cause a failure in the vicinity of the joint. By sealing on the inner diameter of the pipe, the cut end of the pipe is on the "dry" side of the seal such that this does not occur.

In commercial plumbing, MLCP connectors are overwhelmingly of a press-fit type. Such a connector has an inner sleeve over which the pipe is fitted and an outer sleeve which is plastically deformed by pressing (hence the term 'press-fit') in order to compress the body of the connector onto the pipe and, in the process, pressing the pipe onto a seal in the body.

These press fit joints suffer from a number of disadvantages.

In order to compress the connector onto the pipe, a power tool is required. This is a relatively large tool which can be awkward to manipulate. As these connectors are often used in situations where space is limited, or where access is difficult, this makes it difficult to apply and manipulate the tool. This may limit the places where pipes can be placed, or may require a larger volume to be set aside for the pipe and connector. This becomes more of a problem as the pipes are scaled up as more force is required to compress larger diameter connectors.

Many of these types of connectors have a visual indication to show that the crimping has taken place. This may, for example, be in the form of a plastic ring which will fall off the connector once the crimping tool has been applied. Although this provides a visual indication that the crimping tool has been applied, there is no guarantee that the crimping operation has been carried out correctly and that the joint is now sound.

In order to insert the end of the pipe into such a connector, it is necessary to ensure that the end of the pipe is in an appropriate state. In particular, it is necessary to remove any burrs which are formed on the end of the pipe during the cutting operation. However, the press fit connector is designed to have a fairly low clearance in relation to the diameter of pipe with which it is intended to be used. This cuts down the amount of deformation required during the crimping operation as it would otherwise require an impractically high force and create internal stresses on the connector material if it was necessary to deform the material too much during the crimping operation. As such, a chamfer has to be cut onto the inner and outer leading edges of the pipe in order to aid its insertion into the connector. This can be relatively time consuming and, if not done properly, it can create difficulties in making the connection.

This relatively tight interface prior to the crimping of the connector creates a further problem. Such joints are typically pressure tested once an installation is complete in order to test the integrity of the joints. Given that the inner diameter of the pipe is relatively similar to the diameter within the connector on which it seals, it is possible for the joint to pass a pressure test even though the crimping operation has not been carried out or has been carried out incorrectly.

Because the crimping operation plastically deforms the material of the connector, this type of connector is not demountable. Although this may not be a problem for many applications, it limits the use of such connectors to situations where they do not need to be reused.

Another type of connector used for this purpose is the push-fit connector. In contrast to a press-fit connector which relies on plastically deforming the material of the connector, in a push-fit connector the pipe is simply pushed into the end of the connector whereupon the gripping and sealing happens automatically. The connector body has a central portion with a sealing ring which seals on the inside diameter of the pipe.

An example of this is the Wavin smartFIX connector. The body contains a gripper with inner and outer portions which engage with both the inside diameter and the outside diameter of the pipe. The grab ring is spring-loaded to urge it towards the open end of the connector. The outermost part of the connector has a ramped surface which engages with a complementary ramped surface on the gripper so that any force tending to pull the pipe out of the connector would cause these ramped surfaces to engage one another thereby providing an increasing gripping force on the pipe. The outer part of the body is provided with a pair of windows so that the pipe is visible through the connector wall.

<CIT> shows a further push-fit connector suitable for sealing the inside diameter of a plastic or MLCP plumbing pipe. This has a grab ring to hold the pipe in place. A collet is provided, but this is simply to retain an outer sleeve. As with the above-mentioned Wavin connector, this is not demountable. A coloured ring is provided within the connector which is pushed along the connector by the insertion of a pipe and is visible through slots at the distal end of the connector.

These push-fit connectors suffer from a number of problems. The connector is not designed to allow the pipe to be removed so that as with the above-mentioned press-fit connectors they cannot be reused.

In the field of commercial plumbing, installers are used to the idea of using a tool to complete the connection. There is therefore an instinctive mistrust of a connector in which the push-fit connection happens automatically without the application of a tool. The way that a push-fit connector operates means that is has to allow axial movement of the pipe in the connector to engage the gripping. Again this is not popular as it gives an impression of a joint that is not secure.

Further, there is no way to verify that the connection has actually been carried out correctly. In the Wavin smartFIX connector, the windows are relatively small and therefore need to be inspected close up to determine whether the pipe is in place. The windows are a reasonable distance from the end of the pipe such that the window can only be used to verify that the pipe is part-way inside the connector. In <CIT> the coloured ring is also not a reliable indication of the position of the pipe within the connector as it is possible that the ring and the pipe can separate from one another. Under these circumstances, a visual indication of the position of the ring gives a false impression of the position of the end of the pipe.

Both of the above described push-fit connectors, also suffer from the problem set out above concerning the quality of the finish on the cut end of the pipe. Because they rely on components within the connector which can only move with respect to one another in response to movement of the pipe within the connector, the tolerances within the connector again need to be relatively tight so that the deflections required to grip the pipe can provide an adequate gripping force within a short amount of axial travel. Because of this, the end of the pipe must be de-burred and chamfered at both leading edges in order to be able to be inserted within the connector. Even then, the insertion force is likely to be relatively high as the insertion is resisted, to some extent, by the presence of the sealing ring.

Press fit connectors do not scale up well given the additional force needed to deform the material of a larger connector. However, larger sizes of push fit connector are even more difficult to use due to the effort needed to push pipe through the gripper and O-ring.

There is also prior art in the separate field of domestic hose connectors. Such a connectors have been known for decades. An example is disclosed in <CIT>. This shows a connector body with integral fingers to clamp onto the hose pipe. We are also aware of a number of connectors made by Hozelock where there is an inner core which fits within the end of the hose and a separate connection grip which has teeth to grip the hose when a cap is screwed onto the grip component.

It should be noted, however, that these connectors are from a field with fundamentally different requirements from those of the present disclosure. A domestic hose connector is designed to operate at ambient temperatures. By contrast, plumbing connectors are required to connect pipes that carry hot water which is typically at a temperature of at a continuous temperature of <NUM>, and above <NUM> for short periods.

Other connectors are known in different fields. For example, <CIT> discloses a metal connector for connecting with the braided hose. Such braided hoses have a much higher degree of deformability than the pipes which are addressed by the present disclosure. As such, good sealing and gripping can be provided by the higher degree of deflection of the material of the hose itself. This places very different requirements on the connector to those of the present disclosure. A similar connector is disclosed in <CIT>.

<CIT> describes a plastic connector which is again suited to a highly flexible hose. This has a large recess surrounding an outer face of the tubular body, into which the hose is deflected to a significant extent by the collet.

The object of the present disclosure is to address one or more of the above-mentioned problems.

According to the present disclosure, there is provided a pipe connector according to claim <NUM>.

The collet has at least one through slot at a distal end, opposite to the open end, which through slot is exposed in the locked and unlocked configurations allowing the end of the pipe to be visible, in use, through the through slot when the connector is in the locked and unlocked configurations with the pipe inserted.

Such a connector provides a number of benefits over the above-mentioned prior art in the field of commercial plumbing connectors.

The presence of the locking cap which deflects the collet onto the pipe means that a greater degree of inward deflection of the collet can be provided as opposed to the press-fit and push-fit connectors described above. This greater degree of deflection means that the initial opening between the body and the collet can be larger than in the prior art such that there is no need for a chamfer on the cut end of the pipe making the connection process much quicker. It can also provide a lower insertion force so that it is easier to insert the pipe into the connector.

The presence of the locking cap which needs to be rotated to secure the joint means that this is not a 'push-fit' connector as it cannot be made up just by pushing the pipe into the connector. The force required to screw the locking cap into place could be made large enough that it requires the use of a tool. This would help the connector to gain acceptance in the commercial plumbing sector. Such a tool can be smaller and cheaper than the tools required of the above press fit connectors as it is required to perform a screwing action not a crimping action. It can therefore be a simple wrench. Alternatively, the force required to screw the locking cap into place could be made low enough so that the joint can be made up by hand.

Because of the mechanical advantage gained from the screw threaded locking cap, the present disclosure is easily scalable as larger connectors need only slightly more closing torque than smaller ones.

The locking cap is in a first position relative to the collet when unlocked and a second position when locked. This provides a clear visual indication of the state of the connector which can be readily identified from a distance.

The connector can be made as a single use connector if the locking cap is unable to be screwed back from the locked position. However, it can also readily be made demountable provided that the locking cap is able to be unscrewed.

The present disclosure therefore provides numerous and significant benefits over all of the prior art currently available in the field of ID connectors for plumbing applications.

In terms of the art in other fields, in a domestic hose connector, the cap has to be separable from the collet and cannot be captive on it as is preferred in the present disclosure. In a hose connector the legs of the collet can easily be deflected inwardly as the hose is pushed into the body. This will prevent the connecter being properly secured and sealed. Because of this, the hose needs to be pushed into the collet without the cap in the way so that the user can see that the legs are not being deflected inwardly. If this happens they can manually manipulate the hose and/or collet to make sure that the legs are not deflected inwardly. Further if the cap were captive on the collet this would inhibit the ability of the legs to deflect outwardly which would make it difficult to insert the hose. It is therefore essential in a hose connector that the cap can be separated from the collet to use the connector.

As a matter of practicality, all of the above-mentioned problems described in relation to the commercial plumbing do not arise in a domestic hose connector. This, together with the fundamentally different operating conditions mean that, in practice, a hose connector cannot be used in a commercial plumbing environment.

The present disclosure differs from <CIT> and <CIT> which are designed for a different purpose as set out above. Similarly, <CIT> has a large groove in the hollow body and does not have teeth on the collet. The gripping is carried out by deflecting the flexible tube into a groove on the tubular part. None of these references discloses that the locking cap is captive on the collet.

Preferably, in the unlocked configuration, the inner diameter of a first constriction at an open end of the collet is greater than the inner diameter of the part of the collet that receives the pipe distally of the sealing ring. This allows the pipe to be more easily inserted into the collet which is wider at its open end and reduces in diameter deeper into the collet.

In order to enhance the gripping force on the pipe, the collet has two sets of teeth, the sets being axially spaced from one another. Preferably, between the two sets of teeth, the inner wall of the collet bulges inwardly.

Preferably, in use, in the locked configuration, there is no axial movement between the body, collet, locking cap and pipe. This improves on a push fit connector where the pipe can move axially with the collet in the connector such that the connection does not feel as secure to an installer.

The connector is preferably capable of maintaining the seal when exposed to a continuous temperature of <NUM>, preferably <NUM> and more preferably <NUM>. A domestic hose connector cannot operate at these temperatures. The connector should preferably be able to meet ISO <NUM>.

The locking cap and body preferably have an end stop to prevent them from being unscrewed beyond the unlocked configuration. The locking cap can then be screwed to this end stop during the assembly process and the connector is supplied to the end user in a condition in which it is ready to use.

The collet has at least one through slot at its distal end which is exposed in the locked and unlocked configurations allowing the end of the pipe to be visible, in use, through the slot when the connector is in the locked and unlocked configurations with the pipe inserted. This allows the user to verify that the end of the pipe itself has been fully inserted into the connector in both of the locked and unlocked configurations.

While some of the prior art (such as <CIT> and <CIT>) discloses a window in the body through which the pipe can be seen, this is covered by the locking cap so the pipe cannot be seen in the locked configuration. The above configuration allows for the position of the pipe to be visually checked in an inspection carried out after the connector has been fully installed which is not possible in the prior art.

The movement of the locking cap onto the collet means that there is already a clear visual difference between the locked and unlocked configurations. Preferably the distal end of the collet protrudes from the locking cap and is visible to the user in the unlocked configuration and is covered by the locking cap or protrudes to a lesser extent in the locked configuration. This provides an enhanced visual difference in the two configurations.

To provide a further visual indication of the locked configuration, the proximal end of the collet is preferably visible at the proximal end of the connector in the locked configuration, in use, with the pipe in place.

To enhance these visual differences, the collet and locking cap are preferably different colours.

The combination of the fact that a relatively large surface of the side of the collet can be exposed in the unlocked configuration and is a different colour from the locking cap provides a highly visible indication that the connector has been locked. This contrasts with an indication which relies on a window through one of the components, or the end of a component being exposed. With the present arrangement, an inspector can tell, for example, simple by walking beneath a plumbing system with multiple connectors installed in a ceiling space if a connector has not been locked. This cannot be done in prior art commercial plumbing connectors.

Prior art connectors have hexagonal caps to allow the connector to be tightened with a spanner. Optionally, the locking cap is devoid of opposing flat surfaces. This can be achieved, for example, if no part of the locking cap has a hexagonal cross section in a radial plane.

This prevents the application of a conventional spanner to the connector and therefore a user would not try to use such a spanner. Even if they did so they could not gain sufficient purchase on the connector to apply a level of torque which could damage the connector.

The collet and locking cap have complementary end stops to prevent overtightening. This stops overstressing of the connector.

Further the collet and locking cap preferably have complementary features to produce a sound when the locking cap reaches the locked configuration. This indicates to the user that the connector is fully locked and should therefore give them confidence that the connector has been correctly deployed as well as ensuring that they do not try to overstress the connection.

Optionally the complementary features include a break off tab configured to be broken off as the locking cap reaches the locked configuration. A tab which breaks off, as opposed to one which abruptly hits against an opposing surface has been found to produce a louder noise. Optionally, the collet and locking cap are configured to retain the broken off tab in the connector. This avoids loose pieces of plastic in the vicinity of the connector joint which might become caught up in other components and provide unwanted waste and/or a hazard which might interfere with other connectors.

Preferably at least one, and more preferably all of the body, collet and locking cap have a tensile modulus of greater than 2000Mpa and a heat distortion temperature of greater than <NUM>. Preferably all of the body, collet and locking cap have a tensile modulus of greater than 2000Mpa. In a hose connector the hose grip typically has a tensile modulus of <NUM> and a heat distortion temperature <NUM> while the inner core typically has a tensile modulus of <NUM> and a heat distortion temperature of <NUM>.

One or more of the hollow body, collet and locking cap may be made of plastic.

Although the connector may be suitable for other uses, the pipe connector has been designed to be suitable for a commercial plumbing pipe.

An example of the pipe connector in accordance with the present disclosure will now be described with reference to the accompanying drawings, in which:.

The plumbing connector described below shows a double-ended axial connector in which both ends are configured according to the present disclosure. The connector may be applied to other shapes such as a right-angled or T connector. Further, the connector may be provided at only one end and the opposite end may have a different type of connection or be integrated into some other component.

The connector is a plumbing connector for use with a plastic pipe P. This may be a single layer plastic pipe, but is more commonly a multi-layered pipe (MLCP). As can best be seen, for example, in <FIG>, the multi-layered pipe has a number of layers L, typically inner and outer polymeric layers and an intermediate layer of a metal such as aluminium.

Plumbing connectors must be suitable for being used in both cold and hot water systems as well as in heating systems. As such, they must be able to cope with a continuous temperature of <NUM> and must also be able to cope with temperatures of above <NUM> for short periods.

The connector is made from just four components, namely a body <NUM>, an O-ring <NUM>, a collet <NUM> and a locking cap <NUM> as shown, for example, in <FIG>. The body <NUM> is a double-ended body such that it has an O-ring <NUM>, collet <NUM> and locking cap <NUM> at either end.

The components are preferably high performance polymers. For example the body <NUM> may be unfilled PPSU/PSU/PPS/PVDF. The locking cap <NUM> and collet <NUM> the may be the same materials but these may be glass filled. Other possibilities for the cap and collet may be GF PA66/PA12/Amodel/Grivory'.

In broad terms, the body <NUM> has a generally tubular configuration with a throughway <NUM> extending axially along a main central axis X (<FIG>). At the proximal end (i.e. the end closest to the open end of the connector, the distal end being the opposite end furthest from the open end), the body <NUM> has a tubular portion <NUM> over which the pipe P is received as shown, for example, in <FIG>. Partway along the tubular portion <NUM> is an annular groove <NUM> which receives the O-ring <NUM>. As shown in various figures, the O-ring <NUM> seals with the inner diameter of the pipe P as described in greater detail below. Distally of the O-ring <NUM>, the tubular portion <NUM> is provided with a number crenulations <NUM>. These are provided simply as a way of reducing the mass of material required for the body <NUM>.

The collet <NUM> has a lip <NUM> at one end via which it is snap fitted into a groove <NUM> in the body <NUM>. The outer face of the collet <NUM> is provided with a screw thread <NUM>. The locking cap <NUM> has a complementary screw thread <NUM> such that the locking cap <NUM> can be rotated with respect to the collect to lock the connector as described in greater detail below. As well as the screw-threaded engagement, the locking cap <NUM> is also captive on the collet <NUM> as also described in greater detail below.

The collet <NUM> is provided with a plurality of first axial slots <NUM> extending from the proximal end. A plurality of second axial slots <NUM> extend from the opposite end of the collet and these axially overlap with the first axial slots <NUM> but are circumferentially offset with respect to these slots. The collet <NUM> is made of a relatively rigid material and the slots provides the necessary flexibility for the collet to be fitted in place. This is done by forcing the collet <NUM> over the tubular portion <NUM> (as shown in <FIG>) until the lip <NUM> snaps in the groove <NUM>. A number of detents <NUM> are provided at the distal end of the tubular portion <NUM> which engage in the ends of the second axial slots <NUM> to prevent rotation of the collet <NUM> with respect to the body <NUM>. The collet <NUM> is thereby axially and radially fixed with respect to the body <NUM>.

With the collet <NUM> fixed in place, the locking cap <NUM> is then pressed on to the collet <NUM>. The first axial slots <NUM> allow the distal end of the collet to compress and allow the locking cap <NUM> to be pressed onto the collet at least until some of the part of the screw thread <NUM> engages with part of the screw thread <NUM>. The collet may be pushed to a desired location at which the two screw threads <NUM>, <NUM> begin to engage. However, for a more reliable engagement, the locking cap <NUM> is pressed onto the collet beyond the unlocked position and the locking cap <NUM> is then screwed back to the unlocked position shown in <FIG>. When the locking cap <NUM> is in the unlocked position, an inwardly extending annular shoulder <NUM> engages with a complementary outwardly extending shoulder <NUM> on the collet as best shown in <FIG>. This provides a stop to ensure that the locking cap <NUM> cannot be unscrewed beyond this unlocked position, thereby holding the locking cap <NUM> captive on the collet <NUM>.

The first axial slots <NUM> also serve to separate the distal end of the collet <NUM> into four separate legs <NUM>. There could be a different number of first axial slots <NUM> and therefore a corresponding different number of legs <NUM>. Each leg <NUM> has an inner tooth <NUM> and an outer tooth <NUM> closer to the proximal end of the collet than the inner tooth <NUM>. Distally of the inner tooth <NUM> is a pipe receiving portion <NUM> with an inner diameter which corresponds to the outer diameter of the pipe P. The collet has an inward bulge 37A between the two sets of teeth. In the unlocked configuration shown, for example, in <FIG>, at the distal face of the connector, the inner diameter is significantly larger than the outer diameter of the pipe P. This can be seen in <FIG> where the innermost edge <NUM> of the proximal end of the collet is spaced from the pipe P.

The connector is supplied in this unlocked configuration to an end user. This configuration of connector is depicted in <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG>.

As will be appreciated from, for example, <FIG>, the collet <NUM> projects to a reasonably significant extent from the distal end of the cap <NUM>. By comparing <FIG> with <FIG>, it can be seen that there is a significant visual difference between the connector in the unlocked and locked configurations. Also, the proximal end of the collet is substantially flush with the proximal end of the body in the locked configuration so the user has a visual indication that the collet is in the correct position This visual significance can be enhanced if the collet <NUM> and locking cap <NUM> are made from materials of contrasting colours. This makes it easy to inspect the connections from a distance and to determine whether any have yet to be locked and also to confirm that they have been locked.

In this unlocked configuration, the pipes P can be inserted into the connector. They are fully inserted to the position shown in <FIG> and <FIG> where the pipe P abuts against the lip <NUM> in the collet <NUM>.

The connector is specifically designed to provide a low insertion force for the pipe P. A number of features of the design allow for this. As set out above, the inner diameter of the collet <NUM> at the proximal end is significantly larger than the pipe P as can be seen in <FIG>. This allows the pipe to be inserted with little or no interaction with the collet. As can be seen in <FIG>, the outer tooth <NUM> is spaced from the pipe P. The inner tooth <NUM> can be similarly spaced, but is shown in <FIG> with a very minimal interaction with the pipe P which may cause a very small outward deflection of the collet providing a negligible increase in insertion force. The tubular portion <NUM> of the body <NUM> is designed to have a reasonably close tolerance with the inner diameter of the pipe P which again may give rise to a minimal insertion force. As can be seen in <FIG>, the O-ring seal <NUM> will engage with the pipe P on insertion. However, the annular groove <NUM> is designed to be deeper than usual such that insertion of the pipe causes a relatively small compression of the O-ring <NUM> upon insertion.

As will be appreciated for example, from <FIG>, the pipe P is being inserted into a channel which is relatively wide at the opening and gently tapers towards the distal end. As such, the pipe P does not require a lead-in chamfer on either leading edge in order to be inserted in the connector. Further, if there are any burrs on the leading edge of the pipe, these again should not interfere unduly with the connection process as the pipe P can still be inserted into the proximal end of the collect and any burrs which encounter the gently tapering surface of the collet <NUM> will be compressed down onto the pipe as it is inserted.

With the pipes fully in place, it is simply a matter of rotating the locking cap <NUM> in the direction of the arrow shown in <FIG> along the complementary screw threads <NUM>, <NUM> until the locking caps <NUM> reach the locked position as shown in <FIG>, <FIG>, <FIG>, <FIG> and <FIG>.

One of the effects of this has already been described in that the locking cap <NUM> now covers up the collet <NUM> to provide a visual indication of the locked position. Within the connector, the effect of screwing the locking cap <NUM> to the locked position is to compress the collet <NUM> which can best be seen in a comparison of <FIG> with <FIG>.

In the unlocked configuration in <FIG>, the proximal end of the collet <NUM> is within an annular recess <NUM> within the body <NUM>. This annular recess <NUM> terminates at a curved shoulder <NUM> which abuts against the outermost edge of the proximal end of the collet <NUM>. As the locking cap <NUM> is screwed towards the locked position, the shoulder <NUM> immediately runs over the outer face of the proximal portion of the collet <NUM> thereby compressing the legs <NUM> of the collet <NUM> onto the pipe P. This inward deflection of the collet legs <NUM> causes the teeth <NUM>, <NUM> to bite into the outer face of the pipe P. The inward deflection also causes the pipe P to be bowed inwardly as best shown in <FIG>.

As can best be seen in <FIG>, in the vicinity of the groove <NUM> for the O-ring, the outer diameter of the tubular part <NUM> is smaller than the outer diameter of other parts of the tubular part <NUM>. This allows greater deflection of the pipe P to occur in the vicinity of the O-ring <NUM> as shown in <FIG>. As can further be seen from this figure, the teeth <NUM>, <NUM> are positioned on either side of the O-ring to further enhance this effect and to further press the pipe in place in the vicinity of the seal <NUM>. In the locked configuration, the shoulder <NUM> ends up in a radial plane which is in close proximity to the radial plane of the O-ring seal <NUM> and the bulge 37A such that, again, this enhances the compression of the pipe P in the vicinity of the seal <NUM>. This effect is shown in <FIG> where the arrow denotes the regions of maximum compression on the pipe P.

This enhanced deflection of the pipe P in the vicinity of the O-ring seal <NUM> provides very secure gripping of the pipe as well as providing enhanced compression of the O-ring seal <NUM> which, as set out above, is set relatively deeply within the recess <NUM>.

The collet <NUM> and locking cap <NUM> are provided with a feature to prevent over-tightening as shown in <FIG>. The screw thread <NUM> on the collet <NUM> is provided with an end stop <NUM>. The screw thread <NUM> on the end cap <NUM> is provided with complementary end stop <NUM> which abuts against the end stop <NUM> to prevent further screwing of the end cap <NUM> onto the collet <NUM>. As shown in <FIG> the end stops <NUM> and <NUM> have face-to-face contact to provide an abrupt stop. One or both of these could have a ramped surface to provide a let abrupt end stop.

As well as having these end stops, the collet <NUM> and locking cap <NUM> also have features to provide an audible click when the locking cap <NUM> reaches the locked position. This is in the form of an angled lip <NUM> best shown in <FIG> which projects outwardly and distally from the outer face of the distal end of the collet <NUM>. There are effectively four such lips <NUM>, one for each of the legs <NUM>. These engage with a complementary lip <NUM> on the distal end of the cap <NUM>. As the locking cap <NUM> approaches the fully locked position, the lip <NUM> will ride over and compress the angled lips <NUM> whereupon, as the locking cap <NUM> reaches the fully locked position, the angled lips <NUM> will snap into position behind the lips <NUM>. The lips <NUM> help retain the locking cap <NUM> on the collet <NUM> as they can be resiliently biased onto the lip <NUM> to hold the two components in place. This biasing can also help keep the components together when subject to small movements in use caused by thermal effects, or changes in flow of liquid through the pipes which might otherwise serve to work the connection loose over time.

Thus, when the user tightens the joint, they can reliably make up the connector and are prevented from overtightening and stressing the components by the complementary stop <NUM>, <NUM>, as well as being provided with an audible indication of when they have reached the correct position by the above-mentioned feature. This gives them confidence that the connector has been correctly locked as well as wasting further effort and potentially stressing the connector by attempting to overtighten it.

The collet <NUM> and locking cap <NUM> have a further feature which improves security of the connector. As can be seen in <FIG>, the annular lip <NUM> at the distal end of the collet <NUM> is exposed, in use, at the distal end of the end cap <NUM> when in the locked configuration. <FIG> is a cross-section through a plane of the collet <NUM> which is circumferentially offset from the second annular slots <NUM>. However, in the vicinity of these slots the cross section would effectively be the same as in <FIG> same except that the collet <NUM> would not be visible in this plane. In practice, this means that the end of the pipe itself is visible through the slots <NUM> (best appreciated from <FIG>) at the distal end of the collet <NUM>. Thus, unlike the prior art where it is possible only to determine that the pipe may be close to the correct position, or that a secondary component in the form of a coloured ring is in the correct position, the above arrangement allows a user to determine that, in the locked position, the pipe itself is fully inserted within the connector.

Once a plumbing system is connected up and all of the connectors are locked, the system undergoes a pressure test. This provides a further way of verifying that the joints have been correctly made up. The body <NUM> is provided with a further feature which assist in this process. This is shown in <FIG>. The annular groove <NUM> in the tubular part <NUM> of the body <NUM> is provided with a bump <NUM> which projects upwardly from the bottom of the annular groove <NUM>. The effect of this bump is shown in <FIG>. In the unlocked configuration shown in <FIG>, a gap <NUM> feature is formed on the radially innermost side of the O-ring <NUM>. This corresponds to the configuration shown in <FIG> (although the gap and bump are not depicted in this figure). The leakage path for the liquid is from the throughway <NUM> and into the gap between the tubular body <NUM> and pipe P to the left of the O-ring in <FIG>. Without the bump <NUM>, this liquid pressure should, in most circumstances, be sufficient to pass the O-ring seal <NUM> which, at this stage, has barely been compressed at all. However, the presence of the bump <NUM> provides an enhanced and much more reliably defined leakage path behind the O-ring seal <NUM> and through the gap <NUM>. This ensures that the connector is much more likely to fail the pressure test if the connector has not been locked.

A second example of a connector is shown in <FIG>. These views correspond to <FIG> in relation to the first example. Many of the features of the second example are the same as those of the first example and have been designated with the same reference numerals.

The difference between the two examples relates to the external profile of the tubular portion <NUM> and the fact that the O ring is now absent.

Instead, the outer face of the tubular portion is provided with a number of axially-spaced annular barbs <NUM>. As shown, for example, in <FIG>, these barbs have a gently tapering face <NUM> at the proximal end and an abrupt end face <NUM> at the distal end which is approximately in a radial plane. These provide a tooth-like structure which digs into and grips the pipe P as shown in <FIG> when the locking cap <NUM> is screwed into place compressing the collet <NUM>. The barbs <NUM> therefore fulfil the same function as the O-ring <NUM> in the first example. The first example is provided with a number of crenulations <NUM> at the distal end of the tubular portion <NUM>. No such portions are shown in relation to the second example, but could be present if desired.

Three barbs <NUM> are shown in the drawings. This is a reasonable number to provide adequate grip and sealing in the available space. However, a bigger or smaller number of barbs can be used. The barbs <NUM> may also be used in combination with the O ring seal of the previous example.

The mould for making the collet of the first and second examples will now be described with reference to <FIG>.

<FIG> is a perspective view of the mould components shown in a separated form after the formation of the collet <NUM>. The mould comprises an axial core <NUM> which forms the internal features of the collet as described below and a mould body which forms the outer features of the collet <NUM>. The mould body comprises two mould halves <NUM> which are moved radially away from the collet as shown (in exaggerated form) in <FIG>. The mould body also comprises manifold <NUM> which forms the end of the collet and is also provided with manifolds (not shown) through which the plastic is injected. The mould halves <NUM> and the manifold <NUM> are conventional and will not be described in further detail here. The mould also comprises an ejector plate <NUM> as described in greater detail below.

The manner in which this mould operates will now be described with reference to <FIG>. The mould halves <NUM> and manifold <NUM> form the outer profile of the collet <NUM>, but as this is done in a conventional manner, these are not shown in those drawings.

The axial core <NUM> has an inner sleeve <NUM> which is hollow to allow cooling water to circulate. The first core mould part <NUM> is axially slidable on the inner sleeve <NUM> from a forward position in which it abuts second core mould part <NUM> to a rearward position as described below. This movement is driven by axial movement of an outer ring <NUM> engaging with a flange <NUM> on the first core mould part <NUM>.

The second core mould part <NUM> is axially fixed to the inner sleeve <NUM> by a bolt <NUM> and is provided in two parts, namely an end part <NUM> and intermediate part <NUM> which is held in place by being sandwiched between the end part <NUM> and a shoulder <NUM> on the inner sleeve <NUM>.

The external features of the collet <NUM> are formed by the mould halves <NUM> which are withdrawn radially and by the manifold <NUM> which is withdrawn axially in a manner well known in the art.

The formation of the internal features of the collet is described below with reference to <FIG>. This shows a cross-section through one leg <NUM> of the collet. From the innermost edge <NUM>, the inner diameter of the collet increases gradually forming a ramp <NUM>. Axially spaced from the ramp <NUM> is the outer tooth <NUM>, the inward bulge 37A and the inner tooth <NUM>. The inner tooth <NUM> is formed at the junction between the end part <NUM> and the intermediate part <NUM> of the second core part <NUM>. Similarly, the outer tooth <NUM> is formed at an interface between the first core mould portion <NUM> and the intermediate portion <NUM> of the second core portion <NUM>. The ramp <NUM> is formed by a frustoconical face <NUM> on the first core mould part <NUM>.

With the mould components in a closed configuration shown in <FIG>, plastic is injected into the mould cavity via the manifold <NUM> thereby forming the collet <NUM>. Once the plastic has set to the required degree, the mould opening sequence begins.

As a first step, the ring <NUM> is moved away from the mould cavity causing the first core mould part <NUM> to slide along the axial core <NUM> to the position shown in <FIG>. The frustoconical face <NUM> rides up the ramp <NUM> causing the legs <NUM> to be splayed radially outwardly. This peels the inner face of the collet <NUM> away from the second core mould part <NUM> and, in particular, away from the intermediate part <NUM>.

From there, the ejector plate <NUM> is moved to the right thereby pushing on the end of the collet <NUM> to displace it from the second core mould part <NUM> as shown in <FIG>. Because of the above described interaction between the ramp <NUM> and frustoconical face <NUM>, the inner tooth <NUM> is clear of the intermediate part <NUM>. Further, in the position shown in <FIG>, the left flank of the inner tooth <NUM> is separated slightly from the intermediate part <NUM>. Initial movement of the ejector plate <NUM> pushing the collet <NUM> to the right, causing the right flank of the inner tooth <NUM> to ride over the outermost edge of the end part <NUM> thereby providing further separation between the collet <NUM> and the second core mould part <NUM>, this time in the vicinity of the end part <NUM>. This whole process happens very quickly, such that there is a relatively smooth overlapping movement between the two radially outward deflections caused by the ramp <NUM> with a conical face <NUM> and the inner tooth <NUM> with the end part <NUM> and the axial movement caused by the ejector plate <NUM>.

The method provides a way of moulding a relatively complex geometry on the inner face of the collet, in a manner which can be simply and reliably demoulded.

A third example of a connector will now be described with reference <FIG>.

The body <NUM>, O-ring <NUM>, collet <NUM> and locking cap <NUM> broadly operate as described with reference to the first and second examples. The third example relates to a modification which can provide an audible click to a user to indicate that the connector has been fully made up.

With a plastic connector, it can be difficult to get a loud enough noise to provide a reliable audible signal to an operator that the connector has reached its fully made up position. In order to address this, the third example is provided with a break-off tab <NUM> which projects radially outwardly at the opposite end of the collet to which it is attached by a frangible connection. When the locking cap <NUM> is in the fully locked position shown in <FIG>, its end <NUM> will deflect and would ultimately break off the break-off tab <NUM> emitting an audible click. There may be more than one such break-off tab <NUM> on the collet, but one is sufficient to provide the audible indication.

The collet and cap are also provided with the end stop mechanism in the form of saw teeth recesses <NUM> which are formed in an inner face of the connector <NUM> so that they are open towards the end <NUM> of the locking cap <NUM> and complimentary saw teeth <NUM> on the collet. As the locking cap <NUM> nears its end position, the end face <NUM> in the vicinity of the saw teeth recesses <NUM> engages with a complimentary face <NUM> on the collet. Ramp surfaces <NUM>, <NUM> of the complimentary saw teeth ride up one another, thereby causing an increased resistance to further movement of the locking ring <NUM> until the saw teeth <NUM> drop into the saw teeth recesses <NUM> and ultimately their complimentary end faces <NUM>, <NUM> provide an end stop to prevent further rotation of the locking cap <NUM> with respect to the collet <NUM>.

Thus, a user tightening the locking cap <NUM> would begin to feel an increased resistance, followed by a removal of this resistance as the teeth <NUM> drop into the recesses <NUM> which will be accompanied by the click as the break-off tab is severed. This will happen shortly before the locking cap <NUM> reaches the end stops <NUM>,<NUM>. This provides tactile and audible feedback to indicate to the operator that the connection has been fully made up while the end stops <NUM>,<NUM> prevents any further overtightening. The operator can therefore confidently and reliably make up the connection that will not cause them to be over stressed.

A similar idea is shown in the fourth example which will now be described with reference to <FIG>. In this case, there is a break-off tab <NUM> which is close to the end of the collet, but spaced from the end of the collet which is provided with an end flange <NUM>. Again this is engaged by the end of the connector <NUM> which breaks off the tab. However, once broken off, the break-off tab <NUM> is retained between the locking cap <NUM> and the end flange <NUM> as shown in <FIG>. This avoids loose pieces of plastic in the vicinity of the connector joint which might become caught up in other components and provide unwanted waste and/or a hazard which might interfere with other connectors.

Claim 1:
A pipe connector comprising:
a hollow body (<NUM>) having a central throughway defining an axis, the body comprising a tubular part (<NUM>) at at least one end, the tubular part having an outer face to seal, in use, with an inner diameter of a pipe (P) placed over the tubular part (<NUM>):
a collet (<NUM>) fitted over the tubular part (<NUM>) of the body (<NUM>) so as to be axially fixed with respect to the body and having an open end to receive the pipe and being spaced from the tubular part to form a cavity for the pipe, the inner face of the collet having at least one tooth (<NUM>, <NUM>) to grip the pipe (P), in use, and the outer face of the collet having a first screw thread (<NUM>); and
a locking cap (<NUM>) having an inner face with a second screw thread (<NUM>) which is complementary to the first screw thread (<NUM>), wherein screwing the locking cap (<NUM>) onto the collet (<NUM>) from an unlocked configuration to a locked configuration causes inward deflection of the collet to press, in use, the collet onto the pipe and the pipe onto the tubular part to seal the interface between the body and the pipe;
characterised in that the collet has at least one through slot (<NUM>) at a distal end, opposite to the open end, which through slot (<NUM>) is exposed in the locked and unlocked configurations allowing the end of the pipe (P) to be visible, in use, through the through slot (<NUM>) when the connector is in the locked and unlocked configurations with the pipe inserted.