A pipe coupling

Abstract

A pipe coupling comprising a coupling body (1) with a grommet for accommodating a T-tube. The grommet has a tapered surface that causes a clamp (41) to compress against the tube as the clamp moves outward, securing the tube in the grommet. The clamp has a rotating lock. The clamp has a locked rotational position, in which the lock holds it in an outward position, and an unlocked rotational position, in which the clamp can move axially to release and couple the tube. The body (1) and the clamp (41) are provided with a cam surface 43 / follower (56) to provide the locking and unlocking positions. A locking actuator ring (60) rotates with the clamp 41 to actuate the lock. The locking actuator ring (60) extends radially over the outer wall of the coupling body (1) at the open end.

Description

A pipe coupling This disclosure relates to a tube coupling. It has a specific application as a fiber optic cable connector for surface or underground use. However, the concept can be applied more generally to other types of connectors. These fiber optic connectors are used in the installation of fiber optic cables. The cables are used, for example, to provide a fiber optic connection from a junction box to a building, such as an office or home, in order to provide an internet data connection. Fiber optic cables are supplied in bundles of individual fibers that can be several kilometers long. These fiber bundles are run through tubes (often called microducts) that are typically 100 meters long, but can be up to 500 meters long. Therefore, a number of tubes must be connected together to support the entire length of the fiber bundle. Due to the way it is used, there are a number of requirements for a fiber optic cable connector. Its outer diameter should be as small as possible to minimize volume, since connectors are often grouped in large quantities. The connectors must also be highly impact-resistant. Cables are typically buried underground and need to be dug up for maintenance. This is usually done by a worker with a shovel, and the first way the worker will know if a cable is present is when the shovel strikes it. Therefore, the connectors must be robust enough to withstand such an impact. In practice, they must pass a 15J impact test. The connectors have a connection at each end that joins and retains the tube inside the connector. This is done using a crimp or retaining ring. This grips the outer wall of the tube, and any movement that tends to pull the tube out of the connector causes the crimp to tighten its grip on the tube in a well-defined manner. To release the tube, the crimp can be manually moved inward toward the connector. This prevents the crimp from gripping the tube, allowing the tube to be removed from the connector. It is a requirement of fiber optic cable connectors that the crimp must be locked in place to prevent accidental release of the tube. This is conventionally done using a locking clip whose clips fit between the end of the connector body and a crimp ring, thus preventing axial movement between the body and the crimp. These staples have several drawbacks. They are flimsy, exposed components that break easily. Because they are exposed, they become clogged with dirt, making them potentially difficult to remove. They can be accidentally dislodged during installation and then easily lost, rendering the connector unusable unless spare staples are carried. The staples can also shift during installation. The installer may not necessarily be aware that this has happened, as it can occur only when the connector is covered with soil. These issues were addressed in our previous work in WO 2021 / 005100 and WO 2021 / 005041, which disclose a new low-profile connector with impact-resistant and anti-snag features. Of greater relevance is WO 2021 / 005319. This discloses the same connector, but in relation to the way the connector is locked. Specifically, it explains that the crimp lock is formed within the crimp itself, and that the body and crimp are provided with cam features that allow the crimp to be rotated to a position where its axial movement is restricted. The tube is locked within the connector because the crimp cannot move axially and therefore cannot be disengaged from the tube. This application acknowledges our previous document EP 2131089 disclosing a locking ring designed for use on a different type of connector. EP 2131089 discloses the concept of a locking ring rotatably mounted on the body. The body is provided with a cam surface that cooperates with a cam follower on the locking ring. Rotation between the body and the locking ring modifies the axial clearance between the two components. The end of the locking ring rests against the crimp ring. In the locked position, the axial clearance between the locking ring and the body is at its maximum. The engagement between the locking ring and the crimp ring prevents axial movement of the crimp, thus preventing it from moving inward to the position where the tube can be released. As acknowledged in document WO2021 / 005319, this connector is not designed for use with a fiber optic cable connector and, in fact, would not be suitable for such a purpose. The locking ring fits onto the outer surface of the body. This increases the connector's bulk, which contradicts the requirement that the outer diameter of a fiber optic cable connector be as small as possible. The locking ring is exposed to dirt, so during use, dirt particles could become lodged in the locking ring and jam it in the locked position. Furthermore, the locking ring is also susceptible to damage during installation and maintenance, which could cause the locking ring to fail or become stuck in the locked position. This problem is solved in WO 2021 / 005319 by providing the locking mechanism using a cam feature directly between the body and the crimp. This eliminates the need for an external locking ring. The crimp is provided with a pair of axially extending lugs, allowing the user to grip the crimp to unlock it if the tube is to be released. This design overcomes the aforementioned drawbacks. However, the connector is designed to be used with a wide range of sizes and for global use in outdoor environments. In certain circumstances, particularly in cold climates where the user is wearing gloves and especially when working with smaller accessories, the lugs can be difficult to grip. According to this disclosure, a tube coupling according to claim 1 is provided. In EP 2131089, the locking ring can rotate relative to the crimp. It does not rotate with it. As previously stated, EP 2131089 may be unsuitable for use with a fiber optic cable connector, as the locking ring would be exposed to dirt and potential damage. With this adaptation, the locking mechanism, in the form of supplementary cam features, remains located between the body and the crimp, and is therefore internal to the connector. Only the locking actuator ring is external to the connector. The sole function of the locking actuator ring is to allow the user to grip and rotate the crimp. Therefore, any dirt under the locking ring will not interfere with the locking mechanism itself.Furthermore, any minor damage to the locking actuator ring during installation, such as chips or cracks, will not prevent unlocking, as the user will still be able to grip the locking actuator ring and turn the crimp. The presence of the locking actuator ring slightly increases the outer diameter of the connector. However, this increase is relatively limited, as the locking actuator ring can have a relatively low profile and rests directly against the outer face of the coupling body. The crimp and the locking actuator ring may each be provided with at least one complementary locking feature that engages with each other so that the locking actuator ring can rotate with the crimp. This may take the form of at least one lug projecting axially from the open end of the through-conduit, and the locking actuator ring having at least one complementary recess to receive a respective lug. This has the advantage of being compatible with our current design, in which the crimp is already provided with the lugs. The locking actuator ring may then be provided as a separate cap that fits over and is retained on the open end of the connector to engage the complementary locking features. Alternatively, the crimp and locking actuator can be integrally formed in a single molded piece. In this case, to facilitate molding, the part of the locking actuator ring that extends over a radially outer wall of the coupling body at the open end can be circumferentially intermittent. This can also apply to a separate crimp and locking actuator. To improve grip, the portion of the locking actuator ring that extends over a radially outer wall of the coupling body at the open end has gripping features on its outer surface. These may be, for example, grooves, ribs, or serrations. The locking actuator ring can be press-fitted onto the end of the coupling body. This provides a simple and reliable way to secure the locking actuator ring. It can also allow for the retrofitting of an existing connector with a locking actuator ring. This allows for leveraging existing vertical features in the coupling body to provide a press fit. Examples of connectors according to the present invention will be described below, with reference to the accompanying drawings, in which: Fig. 1 is a cross-sectional view of a first connector, with the locking actuator rings shown separately; Fig. 2 is a similar view to Fig. 1, with the locking actuator rings shown in place. Fig. 2A shows the detail shown in circle A in Fig. 2; Fig. 2B shows the detail shown in circle B in Fig. 2; Fig. 3 is an exploded perspective view of a connector inside the coupling body from one end; Fig.4A is equivalent to Fig.3 in its unexploded form; Fig.4B is a cross-section through a plane in Fig.4A through the lugs; Figs. 5A and 5B are views that correspond to Figs. 4A and 4B, which respectively show the cartridge and the crimp in a second angular configuration; Figs. 6A and 6B correspond to Figs. 5A and 5B showing the tube in situ; Fig.7 is a perspective view of the connector in the configuration of Fig.1; Fig. 8 is a perspective view of the connector in the configuration of Fig. 2; Figs. 9A-9D are views similar to Fig. 8 showing various stages of assembly and removal of the connector tube; Fig.10 is a view similar to Fig.2 of a second connector; Fig. 10A shows the detail shown in circle A in Fig. 10; Fig. 10B shows the detail shown in circle B in Fig. 10; Fig.11 is a view similar to Fig.1 showing a third connector; Fig. 12 is a cross-section of the third connector; Fig. 13 is a perspective view of the connector in the configuration of Fig. 11; and Fig.14 is a perspective view of the connector in the configuration of Fig.12. The internal mechanism of the connector is as described in document WO 2021 / 005319 and reference is made to that document for further details on the connector, which is described below. The connector comprises a coupling body 1 having a generally hollow, cylindrical configuration centered on a principal axis X. A connector 2 (described in more detail later) is provided at each end to receive and grip a T-tube, which is sealed by an O-ring 3. The body 1 is molded from a non-opaque plastic. The plastic must be sufficiently transparent so that a visual inspection of the connector externally allows the operator to determine whether there is a fiber or fiber bundle in the center of the connector. Ideally, the body should be as transparent as possible. However, for practical reasons, the body will not be completely transparent. Instead, the body is likely to be translucent enough to allow the fiber to be visible. Suitable materials include polycarbonate, polystyrene, polyester, acrylic, and nylon.Body 1 is formed in a molding process and can optionally be polished to enhance its clarity. As can be seen in the various figures, the outer profile of the body is a smooth configuration, devoid of external ridges, thus eliminating any stress concentrations and holes for dirt accumulation. Body 1 is composed of an outer sleeve 5 and an inner sleeve 6 which are connected by at least one network 7 so as to form a generally uniform gap 10 as described in document WO2021 / 005100. An annular flange 20 with a curved profile provides an end stop for the tubes as described in document WO202 / 005041. Connectors 2 (one at each end of body 1) will now be described in more detail by referring to Figs. 3 to 6B. Connectors 2 consist of two components, namely a cartridge 40 and a crimp 41. The cartridge 40 has a generally annular configuration. The outer surface is provided with a plurality of flexible metal teeth 42. The cartridge 40 is inserted into one end of the body 1 until it seats against the step 11. The teeth 42 grip the wall of the body 1 to ensure that the cartridge 40 is permanently retained in the body 1. At the end of the cartridge 40 adjacent to the step 11, there is a tapered surface 43 that cooperates with the crimp as described below. At the opposite end, the end face of the cartridge 40 is provided with a pair of ramped surfaces 44. Although two such surfaces are shown, there may be only one surface or there may be more than two. Each ramped surface has a low point 45 corresponding to an unlocked configuration and a high point 46 corresponding to a locked configuration within an intermediate sloped face 47.A protrusion 48 is provided at the interface between the highest point 46 and the sloping face 47. A similar protrusion may be provided as the interface between the sloping face 47 and the lowest point 45. The lowest point 45 terminates at the first end stop 49, and the highest point 46 terminates at a second end stop 50. Most of the features of the crimp 41 are conventional. It has a crimp ring 52 from which a plurality of flexible arms 53 extend. Each arm has a head 54 at its distal end, which is provided with an inwardly projecting metal tooth 55. With a T-tube inserted, for example, as shown in Fig. 6B, any movement that tends to pull the T-tube out of the connector causes the teeth 55 to grip the tube. This pulls the heads 54 toward the tapered surface 43 on the cartridge 40, deflecting the arms 53 inward to provide progressively greater gripping force on the T-tube. This serves to hold the T-tube firmly in place. This is the conventional way in which a crimp operates. A pair of cam followers 56 extend from the crimp ring 52 into the ramped surface 44 on the cartridge 40. Although two followers 56 are shown, in practice there are as many followers 56 as there are ramped surfaces 44. Alternatively, the cam arrangement can be reversed so that the ramped surfaces are on the crimp and the followers are on the cartridge. The crimp ring 52 is also provided with a pair of tabs 57 extending from the crimp ring 52 in the opposite direction to the followers 56. As shown in the drawings, the position of the tabs 57 corresponds to a number and position of the followers 56. However, this may not be the case. The components may be offset from each other, and the number of both need not be the same. The operation of the crimp will now be described with reference to Figs. 4 to 6. The position shown in Figs. 4A and 4B is an unlocked position. In this position, the crimp 41 has been rotated so that the cam followers 56 rest on the first end stops 49, with the cam followers at their lowest point 45. As can be seen in Fig. 4B (particularly when compared with Fig.5B), in this position, the crimp 41 has a relatively large axial degree of freedom, as it can move from the position where the heads 54 engage with the conical surface 43 all the way to the left (with reference to Fig. 4B) to the position shown in that figure. If the user holds the tube T in that position, it can be removed because the heads 54 are held away from the conical surface 43, so the crimp cannot grip the tube. The crimp 41 is then rotated in the direction of the arrow to the locked position shown in Figure 5A. As this is done, the followers 56 move upward along the inclined faces 47, over the protrusions 48, giving the user a tactile feeling that a position has been reached, and up to the highest point 46. As will be seen by comparing Fig. 4B and Fig. 5B, in the locked position shown in Fig. 5B, the crimp does not have nearly the same degree of freedom as in Fig. 4B, so it cannot move and remains in an unlocked position where the teeth 55 disengage from the tube T. This is more evident in Figs. 6A and 6B, which show the crimp in the same locked position as in Figs. 5A and 5B, but with the tube in place. Here you can see how the presence of the tube pushes the heads 54 backward on the conical surface 43. The only way to remove the T-tube in this locked configuration is for the user to grasp the tabs 57, rotate the crimp 41 in the direction of the arrow in Figs. 4A to the unlocked position, and manually hold the crimp in the position shown in Fig. 4B while pulling it out of the tube from the body 1. The T-tube can be inserted with the crimp 41 in the unlocked position shown in Figs. 4A and 4B, as this allows for greater reach for the arms 53 to deflect when inserting the tube. However, as can be seen in Fig. 5B, even in the locked position, there is a small clearance between the head 54 and the tapered surface 43. Thus, it is possible to insert the T-tube with the crimp in the locked position. This provides a simple assembly process, as the user only needs to be instructed to insert the tube into the crimp. They do not need to worry about the locking operation. As best seen in Figs. 1 and 2, the crimp ring 52 is configured axially backward within body 1. However, the tabs 57 extend beyond the end of body 1. In this position, the crimp 41 is protected from external impacts by body 1. Furthermore, because it is recessed within body 1, it is somewhat protected from the soil in which the cables are buried. With this connector, the only points where dirt can potentially enter the internal mechanism of the connector are between the crimp ring 52 and the T-tube and between the crimp ring 52 and body 1. However, these are interfaces where tight tolerances can be applied. Any dirt that enters here cannot affect the visibility of the F fiber within body 1.Furthermore, due to the rotating action required to unlock the crimp, even if some dirt gets into these gaps, it is unlikely to jam crimp 41 in place, as a rotating motion can easily generate enough torque to overcome any such jamming. The 57 tabs have right-angled corners. This allows them to be inserted into the cut end of a T-tube and scraped around the inner edge of the tube to remove any burrs that form during the trimming operation and that could otherwise create a snag risk for the F-fiber. The edge may have a different shape to facilitate more effective burr removal. Figures 1, 2, and 7 to 9 show a respective locking actuator ring 60 that fits over each end of the body 1. The locking actuator ring 60 has a generally hollow cylindrical configuration with an outer wall 61 sized to fit closely to the outer wall of the body 1, an end flange 62 extending radially inward from the outer wall 61 to an inner lip 63. The inner lip 63 is provided with through recesses 64 that are generally shaped to complement the shape of the tabs 57, as shown in Figure 2A. The end of the inner lip 63 bears against the crimp ring 52, as shown in Figure 2.The inner face 65 of the outer wall 61 is provided with a circumferential engagement portion, such as a rib or other protrusion, 66, which is configured to engage with feature 67, for example, a press fit behind feature 67, on the outer face of body 2. As shown in Fig. 7, the feature in this case is the vertical arrows 67 present on both sides of the connector. These are sufficient to hold the locking actuator rings 60 in place. This allows the use of an unmodified connector to secure the locking actuator ring 60. In addition, or alternatively, the connector may have features such as protruding lugs specifically provided to engage with the circumferential rib 66. Once the connector has been assembled as shown in Fig.1, the locking actuator rings 60 are then pressed into each end of the connector until the circumferential rib 66 is pressed behind the feature 67. Inward axial movement is prevented by the engagement of the inner lip 63 with the crimp ring 52. A small amount of outward movement of the locking actuator ring 60 is provided by a gap between the arrows 67 and the vertical locking symbols 68 (which can again be replaced by a lug) in which the circumferential rib 66 can slide (see Figs. 2 and 2B). Therefore, when the crimp moves radially outward as described above in relation to Figs. 4 to 6, the locking actuator ring 60 can move correspondingly, for example, axially outward with the crimp. The operation of the connector is now described with reference to Figs. 7 to 9B. The end flange 62 is provided with indicators 70 comprising locking / unlocking symbols and arrows that show the user in which direction the locking actuator ring 60 should be turned to lock and unlock it. The symbols 67, 68 on the body 1 are no longer visible during use and serve to retain the locking actuator rings 60 as previously described. The outer face of the locking actuator ring 60 is provided with a series of grooves 72 to facilitate gripping. The connector is supplied with the locking mechanism in the locked position as described above in relation to Figs. 5A and 5B. The T-tube is then presented to the connector as shown in Fig. 9A and inserted as shown in Fig. 9B. That is all that is needed to establish the connection. To remove the T-tube, the locking actuator ring 60 is moved to the unlocked position by rotating it in the direction of arrow 73 in Fig. 9C. The engagement between the recesses 64 and the tabs 57 causes this rotation to also rotate the crimp, thus moving it from the locked position shown in Figs. 5A and 5B to the unlocked position shown in Figs. 4A and 4B. The locking actuator ring 60 is then clamped to the coupling body to prevent the teeth 55 from engaging with the T-tube and to allow its removal. The 60 locking actuator ring is easier for a user to manipulate than the 57 tabs. This offers the option of providing a range of connectors where smaller diameter connectors are supplied with the 60 locking actuator rings, while larger ones are supplied only with the 57 tabs. As an additional option, the 60 locking actuator ring can be used with a wider range of connectors in countries with colder climates than in countries with warmer climates. A second example of a connector is shown in Figs. 10, 10A, and 10B. This is identical to the first connector in all respects, except that the recesses 64 are blind recesses that do not extend completely through the locking actuator ring 60, as shown in Fig. 2A. This design extends the axial length of the connector but does not leave the tabs 57 exposed at the end of the connector. A third example of a connector is shown in Figs. 11 to 14. In this case, the crimp 41 and the locking actuator ring 60 are integrally formed as a single body 80. The single body 80 is a single molded component, formed from one or more molds. The molds may have one or more grooves or sections. For example, the molds may have molding grooves or sections that allow the formation of the crimp portion of the body 80. The body 80 has an outer wall 81 that is circumferentially intermittent. In particular, it is formed by two arched wall portions 82 on opposite sides of the body 80. These extend for approximately one-quarter of the circumference of the body 80 with intervening gaps 83 that also extend for approximately one-quarter of the circumference of the body 80. This allows the molding grooves that form the inner portion of the body 80 to be moved radially outward. The outer wall 81 is also axially shorter than the outer wall 61, as can be seen by comparing Figures 2 and 12. This allows the mold to create the toothed portion of the crimp without being obstructed by the outer wall 81. The coupling ring 80 is provided with axial openings 84 that have a circumferential extent similar to that of the outer walls 81 to allow the axial insertion of a mold portion to form the inner face of the outer wall 81. Cam followers 85 (equivalent to followers 56 in the first example) are molded onto body 80. The coupling ring 80 fits onto the end of the connector as described above, and the locking and gripping operations are also as described above.

Claims

1. A tube coupling comprising a coupling body (1) having an open-ended through-channel for receiving a tube, a crimp (41) located at the open end of the through-channel having a crimp ring (52) and a plurality of flexible arms (53) generally extending axially from the crimp ring into the through-channel, the through-channel having a tapered surface (43) converging toward the open end, and the crimp arms (53) having heads (54) at their distal ends for engaging both the tapered surface (43) and a tube (T) extending, during use, through the crimp into the through-channel to be compressed against the tube by the tapered surface with outward movement of the crimp relative to the through-channel to secure the tube in the through-channel; and a crimp lock (44, 56, 60) formed in the crimp,The crimp has a locked rotating position in which the locking mechanism holds the crimp (41) in an outward-facing tube-fixing position and an unlocked rotating position in which the crimp can be moved axially with respect to the through-tube to release and engage the tube by means of the crimp; wherein one of the coupling bodies and the crimp is provided with a cam surface (44) and the other of the coupling body and the crimp is provided with a cam follower (56), the cam surface being provided to provide the locking and unlocking positions. It is characterized by a locking actuator ring (60) that rotates with the crimp to actuate the locking mechanism, the locking actuator ring extending over a radial outer wall of the coupling body (1) at the open end.

2. A tube coupling according to claim 1,wherein the crimp (41) and the locking actuator ring (60) are each provided with at least one complementary locking feature (57, 64) that engages with each other so that the locking actuator ring can rotate with the crimp.

3. A pipe coupling according to claim 2, wherein at least one complementary locking feature is provided by at least one lug (57) projecting axially from the open end of the through-conduit, and by the locking actuator ring having at least one complementary recess (64) for receiving a respective lug.

4. A pipe coupling according to claim 1, wherein the crimp (41) and the locking actuator ring (60) are integrally formed.

5. A pipe coupling according to claim 4,wherein the crimp (41) and the locking actuator ring (60) are formed as a single molded piece.

6. A tube coupling according to any of the preceding claims, wherein the portion (81) of the locking actuator ring (60) extending over a radially outer wall of the coupling body (1) at the open end is circumferentially intermittent.

7. A tube coupling according to any of the preceding claims, wherein the portion of the locking actuator ring (60) extending over a radially outer wall of the coupling body (1) at the open end has gripping features on its outer surface.

8. A tube coupling according to any of the preceding claims, wherein the locking actuator ring (60) is press-fitted to the end of the coupling body (1).

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