End fitting system adapted to be mounted at an end portion of a protective plastic pipe

Abstract

End fitting system to be mounted at an end portion of a protective plastic pipe into which an elongated object passes. The system is composed of a one-part rigid housing of fibres reinforced plastic and a single compressible sealing member. The housing delimits a pipe bore and a chamber receiving the sealing member between the pipe bore and an end wall. A passage in the end wall, the chamber, and the pipe bore are open at an open lateral side. A pipe retention portion protrudes inwardly and has a stab flank, a load flank, and a crest ridge. After the housing being applied laterally over the sealing member mounted on the elongated object, the fitting system is to be pushed onto the pipe which slides over the stab flank into initial engagement with the sealing member. The crest ridge extends in a plane perpendicular to the pipe bore axis and over an arc segment allowing the fitting system to be axially pushed further to cause subsequent compression of the sealing member.

Description

[0001] END FITTING SYSTEM ADAPTED TO BE MOUNTED AT AN END PORTION OF A PROTECTIVE PLASTIC PIPE

[0002] The present invention relates to the field of end fitting systems which are adapted to be mounted at an end portion of a protective plastic pipe into which at least one elongated object passes. For example, the elongated object is a cable, e.g. an electric power cable and / or communication cable, e.g. an optical fibre cable. These fitting systems provide a seal that prevents ingress of fluid, e.g. water, e.g. ground water, or gas, or other matter, into and / or out of the protective plastic pipe. In these fitting members the sealing member may clamp onto the elongated object and thereby may also provide some strain relief for the elongated object.

[0003] In W02020204699 an end fitting system according to the preamble of claim 1 is disclosed, in particular with reference to figures 4a-c thereof. This known end fitting system is composed of a one-part rigid housing and of a single compressible sealing member, see e.g. figure 7b of the W02020204699. The housing defines, at the end of the pipe bore adjoining the chamber, a single pipe retention portion protruding inwardly from the entire inner circumference into the pipe bore, which pipe retention portion has a stab flank and a load flank, wherein a crest ridge is defined by an apex where the stab flank adjoins the load flank. The housing is mountable laterally over the sealing member and the elongated object so that the sealing member is received in the chamber allowing the fitting system to be pushed onto an end portion of the protective pipe. Herein the protective pipe enters into the pipe bore via the insertion end and then slides over the stab flank of the retention portion upon elastic deformation of the housing into initial engagement of the protective pipe with the sealing member. W02020204699 discloses that the housing can be made of a fibre reinforced plastic material, e.g. a glass fibre reinforced plastic material. lnW02020204699 the crest ridge extends over a segment of a helix, so with a pitch, such that the pipe retention portion is embodied as a helical thread creating portion which is adapted to create a helical thread having a lead or pitch into the exterior of the protective plastic pipe. It is envisaged in this prior art end fitting system of figures 4a-c of W02020204699 that the user, once the initial engagement is obtained by a pushing action, then proceeds with a screwing action, further screwing the fitting system onto the end portion of the protective plastic pipe and therein compressing the sealing member. These one-part housing embodiments of the fitting system are manufactured in various sizes, depending on the outer diameter of the protective pipe onto which the system is mounted. In the field, known diameters of protective pipes for which systems with one-part housings are provided are 4, 5, 6, 7, 8, and 10 mm.

[0004] Generally, a one-part housing fitting system can be mounted quicker than the two-part and three-part housing versions, of which examples are discussed in W02020204699. The latter version require more actions of the user performing the installation of the fitting system.

[0005] In the field, time pressure is high when installing, for example, optical fibre networks. For example, about 100 protective pipes each containing an optical fibre cable may terminate in a single cabinet. This requires the user to apply a fitting system to each end of the protective pipes.

[0006] The present invention therefore aims to reduce the installation time by optimizing the fitting system for quick and reliable installation.

[0007] The present invention provides an end fitting system according to the preamble of claim 1, which is characterized in that the crest ridge of each retention portion extends in a plane perpendicular to the pipe bore axis and over an arc segment about the pipe bore axis, wherein the arc segment of each retention portion is between 30° and 90°, so that the fitting system is configured to be axially pushed, from said initial engagement, further over the protective pipe to cause subsequent compression of the compressible sealing member which then seals onto the end of the protective plastic pipe.

[0008] Due to the limited circumferential extension of the crest ridge of each retention portion, which is much smaller than the about 300° extension of the single thread creating portion of the prior art embodiment of figures 4a-c of W02020204699, the stresses in the housing of the installed fitting system remain limited even as the housing is made of inherently stiff fibre reinforced plastic material. Also, the stiffness and strength of the retention portion(s) of the housing leads to a desirable resistance against pull-out of the protective pipe. For example, axial pull-out tests have shown that a retention portion will effectively create a small axial groove in the protective pipe under a test load, yet the housing does not widen so that the retention portion does not become detached from the pipe.

[0009] In practice, a user may choose to twist the fitting system once a desired compression of the sealing member has been achieved by the pushing action. In contrast to the prior art embodiments of W02020204699 this twisting does not result in the formation of a helical threading in the exterior of the protective pipe. Instead a circumferential groove without pitch is formed by the stiff and strong retention portion(s). The twist may be just over a small angle, e.g. less than half a revolution or turn.

[0010] In an embodiment, the arc segment of each retention portion is between 45° and 60°. This allows for a retention portion that is not too small, so that it would become fragile, and of limited circumferential extension so that local stresses caused by the inwardly protruding retention portion(s) are limited.

[0011] In a practical embodiment, the housing defines multiple retention portions which are distributed about the inner circumference of the pipe bore and circumferentially spaced from one another. For example, the spacing between adjacent retention portions is at least 30°, e.g. at least 45°.

[0012] In a practical embodiment, the housing defines exactly three retention portions, wherein one retention portion is arranged opposite the open lateral side of the housing, and wherein the two other retention portions are located adjacent the open lateral side of the housing. The three retention portions effectively retain the pipe.

[0013] In a practical embodiment, the crest ridges of the multiple retention portions are arranged in a common plane which extends perpendicular to the bore axis. This enhances retention of the pipe and may, in embodiments, also be of benefit when the user gives a final twist to the housing at the end of the installation process. The retention portions will then each create a circumferential groove, which grooves may join one another to form a complete groove extending circumferentially about the pipe. This may enhance the grip on the pipe and may result in a lower stress in the housing.

[0014] In a practical embodiment, the load flank is at an angle between 0 and 15 degrees relative to the plane perpendicular to the axis of the pipe bore, preferably perpendicular to the axis of the pipe bore.

[0015] In a practical embodiment, the stab flank is conical at an angle between 15° and 30° relative to the axis of the pipe bore, e.g. about 20° relative to the axis of the pipe bore. In a practical embodiment, the crest ridge of each retention portion is curved, e.g. extends concentrically to the inner circumference of the pipe bore, seen in direction of the pipe bore axis.

[0016] In a practical embodiment, the housing is injection molded of a fibre reinforced plastic material containing at least 10% by weight of fibres, e.g. between 10% and 25%, e.g. of glass fibres.

[0017] In an embodiment, the housing defines at least one handle portion protruding outwards and configured to be engaged by the user manually for twisting the housing after axial pushing the fitting system has achieved compression of the compressible sealing member, the one or more retention portions then creating a circumferential groove in the protective pipe.

[0018] The present invention also relates to a housing for use with a compressible sealing member to form a fitting system as described herein.

[0019] The present invention also relates to a method for mounting a protective plastic pipe end fitting system as discussed herein at an end portion of a protective plastic pipe into which at least one elongated object passes, the fitting system providing a seal that prevents transfer of fluid into and / or out of the protective plastic pipe.

[0020] The method comprises:

[0021] - mounting the sealing member about an elongated object which extends from the end portion of the protective pipe into which the elongated object has already been inserted,

[0022] - applying the one-part housing laterally over the sealing member mounted on the elongated object so that the sealing member is received in the chamber and the elongated object is received in the passage of the end wall and in the pipe bore,

[0023] - pushing the fitting system onto the end portion of the protective pipe wherein the protective pipe enters into the pipe bore via the insertion end and then slides over the stab flank of the retention portion upon elastic deformation of the housing into initial engagement of the protective pipe with the sealing member,

[0024] - pushing the fitting system, from said initial engagement, axially further over the protective pipe to cause subsequent compression of the compressible sealing member which then seals onto the end of the protective plastic pipe. In an embodiment, the method further comprises, after axial pushing the fitting system has achieved compression of the compressible sealing member:

[0025] - twisting the housing so that the one or more retention portions then create a circumferential groove in the protective pipe, e.g. the housing defining at least one handle portion protruding outwards and configured to be engaged by the user manually for the twisting of the housing. For example, the twisting is over less than one revolution, e.g. at most half a revolution.

[0026] The invention will now be discussed with reference to the drawings. In the drawings:

[0027] - fig. 1 shows an example of the one-part housing of a fitting system according to the invention,

[0028] - fig. 2 shows another view of the housing of figure 1 ,

[0029] - fig. 3 shows another view of the housing of figure 1 ,

[0030] - fig. 4 shows another view of the housing of figure 1 ,

[0031] - fig. 5 shows a longitudinal section of the housing of figure 1 ,

[0032] - fig. 6 shows the housing of figure 1 in a view onto the insertion end of the pipe bore,

[0033] - fig. 7 shows in longitudinal section the fitting system when installed,

[0034] - figs. 8a - 8g show another embodiment of the one-part housing of a fitting system according to the invention.

[0035] With reference to figures 1 - 7 an example will be discussed of an end fitting system 1 adapted to be mounted at an end portion of a protective plastic pipe 10 into which an elongated object 5, here an optical cable 5, passes.

[0036] Generally, the fitting system is adapted to provide a seal that prevents transfer of fluid, such as liquid, e.g. water, moisture, gas, into and / or out of the protective plastic pipe 10 with the cable 5 installed therein.

[0037] The fitting system 1 is composed of two components, namely:

[0038] - a one-part rigid housing 20, which housing is made of a fibre reinforced plastic material, e.g. glass fibre reinforced plastic material, and

[0039] - a single compressible sealing member 30. For example, the sealing member 30 is made of a synthetic rubber, e.g. a thermoplastic elastomer (TPE), or of a silicone. In a practical embodiment, the housing 20 is injection molded of a fibre, e.g. glass fibre, reinforced plastic material, e.g. containing at least 10% by weight of fibres, e.g. glass fibres, e.g. between 10% and 25%. The housing 20 has a high stiffness and strength.

[0040] The housing 20 delimits a pipe bore 21 which is adapted to receive therein an end portion 11 of the protective plastic pipe 10. The pipe bore has an inner circumference 21a which is incomplete due to the lateral open design of the housing at side 26.

[0041] The pipe bore 11 has a pipe bore axis 21 b and an insertion end 22 for axial insertion of the end portion of the protective pipe 10.

[0042] The insertion end 22 can be bevelled to enhance introduction of the pipe end.

[0043] The housing has an end wall 24 transverse to the axis 21b and remote from the insertion end 22. The housing defines a sealing member receiving chamber 23 adapted to receive therein the sealing member 30 in a non-compressed condition. The chamber 23 is arranged in line with the pipe bore 21 , between the pipe bore 21 and the end wall 24.

[0044] The end wall 24 is provided with a passage 25 therein for the elongated object 5.

[0045] As shown, the passage 25, the sealing member receiving chamber 23, and the pipe bore 21 are laterally open at the open lateral side 26 of the housing 20.

[0046] The compressible sealing member 30 has a sealing member body 31 with a pipe contacting end face 32 and a counter end face 33 opposite said pipe contacting end face. When the member 30 is compressed, the end face 33 is pressed against the end wall 24.

[0047] The sealing member body31 delimits one axial passage 34 therein and has a split allowing to mount the sealing member 30 about the elongated object 5 which extends from the end portion of the protective pipe 10 into which the elongated object 5 has already been inserted.

[0048] The housing 20 defines, at or near the end of the pipe bore adjoining the chamber, at least one pipe retention portion protruding inwardly from the inner circumference into the pipe bore 21. Here three pipe retention portions 40a, 40b, 40c are present.

[0049] Each pipe retention portion 40a, b, c has a stab flank 43 and a load flank 44. A crest ridge 45a, b,c is defined by an apex where the stab flank 43 adjoins the load flank 44. The housing 20 is configured to be applied laterally over the sealing member 30 already mounted on the elongated object 5 so that the sealing member 30 is received in the chamber 23 and the elongated object 5 is received in the passage 25 of the end wall 24 and in the pipe bore 21. The fitting system is to be pushed onto the end portion of the protective pipe 10. In this action, the protective pipe 10 enters into the pipe bore 21 via the insertion end 22 and then slides over the stab flank of the retention portions 40a, b, c upon elastic deformation of the housing 20 into initial engagement of the protective pipe with the sealing member 30.

[0050] As shown the crest ridge 45a, b,c of each retention portion 40a, b,c extends in a plane perpendicular to the pipe bore axis 21b and over an arc segment about the pipe bore axis 21b. This arc segment of each retention portion 40a, b,c is between 30° and 90°, seen in direction of the pipe bore axis 21b as in figure 6.

[0051] As shown the crest ridge 45a, b,c of each retention portion 40a, b,c is curved, preferably extends concentrically to the inner circumference of the pipe bore 21 , seen in direction of the pipe bore axis 21b as in figure 6.

[0052] The fitting system is configured to be axially pushed, from this initial engagement, further over the protective pipe to cause subsequent compression of the compressible sealing member 30 which then seals onto the end of the protective plastic pipe 10.

[0053] Once sufficient compression of sealing member 30 is attained, in practice by the user exerting a sufficient pushing force, the housing 20 will remain clampingly retained on the end of the pipe 5. No further provision of additional elements of a fitting system is required, e.g. no second housing part, no adhesive, etc.

[0054] It is shown that, as preferred, the arc segment of the ridge 45a, b,c of each retention portion 40a, b,c is between 45° and 60°.

[0055] The multiple retention portions 40a, b,c are distributed about the inner circumference 21a of the pipe bore 21 and circumferentially spaced from one another.

[0056] As preferred, the housing 20 defines three retention portions 40a, b,c, wherein one retention portion 40b is arranged opposite the open lateral side of the housing. The two other retention portions 40a, 40c are located adjacent the open lateral side 26 of the housing 20. As shown, the crest ridges of the multiple retention portions 40a, b,c are arranged in a common plane which extends perpendicular to the pipe bore axis 21b.

[0057] It is illustrated that the load flanks 44 are each at an angle between 0 and 15 degrees relative to the plane perpendicular to the axis 21 b of the pipe bore, here perpendicular to the axis of the pipe bore.

[0058] It is illustrated that the stab flanks 43 each are conical at an angle 43a between 15° and 30° relative to the axis 21 b of the pipe bore, here about 20° relative to the axis of the pipe bore.

[0059] As discussed, it is envisaged that housing 20 can be made in various sizes, e.g. the size being configured to be combined with a protective pipe having an outer diameter of 4, 5, 6, 7, 8, or 10 mm.

[0060] With reference to the figures 8a- 8g another embodiment of the one-part housing 120 of a fitting system according to the invention is discussed. Here features are denoted with the same reference numerals as the corresponding features in the embodiment shown in figures 1-7. The features, their design, function, and / or interaction, are discussed above, which is not repeated here.

[0061] In this embodiment the housing 120 defines a handle portion, here two diametrically opposed handle portions 127, which each protrude outwards and are configured to be engaged by the user manually for twisting the housing 120 after axial pushing the fitting system has achieved the desired compression of the compressible sealing member 30. The twist may be less than one revolution, e.g. less than half a revolution. When twisting the housing at the end of the installation process, so with the sealing member 30 already properly compressed, the one or more retention portions 40a, b,c then create a circumferential groove in the protective pipe. As the ridges of these retention portions are located in a common plane, the twisting may create one continuous annular groove in the protective pipe. This may enhance the grip on the pipe and may serve to further lower the internal stress in the housing 120.

Claims

C L A I M S1 . End fitting system (1) adapted to be mounted at an end portion of a protective plastic pipe (10) into which an elongated object (5) passes, the fitting system being adapted to provide a seal that prevents transfer of fluid into and / or out of the protective plastic pipe (10), wherein the fitting system (1) is composed of:- a one-part rigid housing (20; 120), which housing is made of a fibre reinforced plastic material, e.g. glass fibre reinforced plastic material,- a single compressible sealing member (30), wherein the housing delimits a pipe bore (21) that is adapted to receive therein an end portion (11) of a protective plastic pipe, the pipe bore having an inner circumference (21a), a pipe bore axis (21b), and an insertion end (22) for axial insertion of the end portion of the protective pipe, wherein the housing has an end wall (24) remote from the insertion end (22), and wherein the housing defines a sealing member receiving chamber (23) adapted to receive therein the sealing member (30) in a non-compressed condition, which chamber (23) is arranged in line with the pipe bore (21), between the pipe bore and the end wall (24), wherein the end wall (24) is provided with a passage (25) therein for the elongated object (5), wherein said passage (25), the sealing member receiving chamber (23), and the pipe bore (21) are laterally open at an open lateral side (26) of the housing, wherein the compressible sealing member (30) has a sealing member body (31) with a pipe contacting end face (32) and a counter end face (33) opposite said pipe contacting end face, said sealing member body delimiting one axial passage (34) therein and having a split allowing to mount the sealing member (30) about an elongated object (5) which extends from the end portion of the protective pipe (10) into which the elongated object (5) has already been inserted, wherein the housing (20; 120) defines, at or near the end of the pipe bore adjoining the chamber (23), at least one pipe retention portion (40a, b,c) protruding inwardly from the inner circumference (21a) into the pipe bore, which pipe retention portion has a stab flank (43) anda load flank (44), wherein a crest ridge (45a, b,c) is defined by an apex where the stab flank (43) adjoins the load flank (44), wherein the housing (20;120) is configured to be applied laterally over the sealing member (30) mounted on the elongated object (5) so that the sealing member is received in the chamber (23) and the elongated object is received in the passage (25) of the end wall and in the pipe bore (21), then allowing for the fitting system to be pushed onto an end portion of the protective pipe (10) wherein the protective pipe enters into the pipe bore (21) via the insertion end (22) and then slides over the stab flank (43) of the retention portion (40a, b,c) upon elastic deformation of the housing into initial engagement of the protective pipe with the sealing member (30), characterized in that the crest ridge (45a, b,c) of each retention portion (40a, b,c) extends in a plane perpendicular to the pipe bore axis (21b) and over an arc segment about the pipe bore axis, wherein the arc segment of each retention portion is between 30° and 90°, so that the fitting system is configured to be axially pushed, from said initial engagement, further over the protective pipe (10) to cause subsequent compression of the compressible sealing member (30) which then seals onto the end of the protective plastic pipe (10).

2. End fitting system according to claim 1, wherein the arc segment of each retention portion (40a, b,c) is between 45° and 60°.

3. End fitting system according to claim 1 or 2, wherein the housing (20; 120) defines multiple retention portions (40a, b,c) which are distributed about the inner circumference of the pipe bore (21) and circumferentially spaced from one another.

4. End fitting system according to claim 1 or 2, wherein the housing defines three retention portions (40a, b,c), wherein one retention portion (40b) is arranged opposite the open lateral side of the housing, and wherein the two other retention portions (40a, c) are located adjacent the open lateral side (26) of the housing.

5. End fitting system according to claim 3 or 4, wherein the crest ridges (45a, b,c) of the multiple retention portions are arranged in a common plane which extends perpendicular to the bore axis (21b).

6. End fitting system according to any one or more of claims 1 - 5, wherein the load flank (44) is at an angle between 0° and 15° relative to the plane perpendicular to the axis (21b) of the pipe bore, e.g. perpendicular to the axis of the pipe bore .

7. End fitting system according to any one or more of claims 1 - 6, wherein the stab flank (43) is conical at an angle between 15° and 30° relative to the axis (21b) of the pipe bore, e.g. about 20° relative to the axis of the pipe bore.

8. End fitting system according to any one or more of claims 1 - 7, wherein the housing (20; 120) is injection molded of a fibres reinforced plastic material containing at least 10% by weight of fibres, e.g. glass fibres, e.g. between 10% and 25% by weight of fibres.

9. End fitting system according to any one or more of claims 1 - 8, wherein the housing (120) defines a handle portion (127) protruding outwards and configured to be engaged by the user manually for twisting the housing after axial pushing the fitting system has achieved compression of the compressible sealing member (30), the one or more retention portions (40a, b,c) then creating a circumferential groove in the protective pipe.

10. Method for mounting a protective plastic pipe end fitting system according to one or more of claims 1 - 9 at an end portion of a protective plastic pipe into which at least one elongated object (5) passes, the fitting system providing a seal that prevents transfer of fluid into and / or out of the protective plastic pipe, wherein the method comprises:- mounting the sealing member (30) about an elongated object (5) which extends from the end portion of the protective pipe (10) into which the elongated object (5) has already been inserted,- applying the one-part housing (20; 120) laterally over the sealing member (30) mounted on the elongated object (5) so that the sealing member is received in the chamber (23) and the elongated object is received in the passage (25) of the end wall (24) and in the pipe bore (21),- pushing the fitting system onto the end portion of the protective pipe (10) wherein the protective pipe enters into the pipe bore (21) via the insertion end (22) and then slides over the stab flank (43) of the retention portion upon elastic deformation of the housing into initial engagement of the protective pipe with the sealing member (30),- pushing the fitting system, from said initial engagement, axially further over the protective pipe to cause subsequent compression of the compressible sealing member (30) which then seals onto the end of the protective plastic pipe (10).

11. Method according to claim 10, wherein the method further comprises, after axial pushing the fitting system has achieved compression of the compressible sealing member (30) :- twisting the housing (20; 120) so that the one or more retention portions then create a circumferential groove in the protective pipe, e.g. the housing (120) defining at least one handle portion (127) protruding outwards and configured to be engaged by the user manually for the twisting of the housing, e.g. two diametrically opposed handle portions (127).

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