GB2123106A

GB2123106A - Conduit end fitting

Info

Publication number: GB2123106A
Application number: GB08219871A
Authority: GB
Inventors: Graham Edward Roberts
Original assignee: Smiths Group PLC
Current assignee: Smiths Group PLC
Priority date: 1982-07-08
Filing date: 1982-07-08
Publication date: 1984-01-25
Also published as: GB2123106B

Abstract

An end fitting for use with corrugated conduit has a tubular body member (10) with a portion (19) adjacent one end defining part of its bore being axially slotted so as to impart radial flexibility and having internally beads (22) maintained in engagement with the conduit corrugations by a sleeve member (20) with a cooperating surface (23) retained in position by a snap-fit arrangement (24 and 26) between the body and sleeve members. Axial displacement of the sleeve member over the body member, for example to a second snap-fit position, allows radial flexing of the portion (19) for insertion and withdrawal of the conduit. Sealing means eg compression rings may be disposed between conduit and inner bore of the tubular body member. The corrugations may be helical with the internal beads being discontinuous and extending around the recess 14. <IMAGE>

Description

SPECIFICATION Conduit end fittings This invention relates to end fittings for conduits, and, in particular, to end fittings for use with flexible corrugated conduits.

According to the present invention there is provided an end fitting for a corrugated conduit comprising a generally tubular body member having a bore in which an end of the conduit is to be received, a portion of the tubular body member having means thereon for engaging with the conduit corrugations to retain the conduit in said bore and being radially displaceable to facilitate insertion of the conduit end into the bore from one end thereof, and a sleeve member which extends around the outer surface of the tubular body member, wherein the sleeve member is adapted for movement axially of the tubular body member to a position in which the sleeve member is arranged to co-operate with the tubular body member to inhibit radial displacement of said portion of the tubular body member and thereby maintain said engagement means in engagement with the conduit corrugations, and wherein the sleeve member is retained on the tubular body member in said position by means of a snap-fit arrangement.

The radially displaceable portion of the tubular body member, which may conveniently be formed of flexible resilient material, preferably comprises a region of the tubular body member adjacent to, and including, said one end of the tubular body member. The tubular body member preferably is provided with a plurality of slots which extend axially of that member from said one end along a length of the member defining the radially displaceable portion to permit radial flexing of the portion.

The sleeve member and tubular body member may include respective tapered surfaces which are adapted to co-operate with one another when the sleeve member is moved axially of the tubular body member to said position. to inhibit radial movement of the portion of the tubular body member.

The snap-fit arrangement preferably comprises respective co-operating protrusion and recess means on the sleeve and tubular body members. In this respect, one of the members may include an annular protrusion and the other an annular, co-operating, recess.

The sleeve member is preferably mounted on the tubular body member for slidable movement between a second position in which limited radial displacement of said portion of the tubular body member is permitted so as to facilitate insertion of the conduit end into the bore and said first-mentioned position.The tubular body means may include means for engaging with the sleeve member in said second position such that the sleeve member is captively mounted on the tubular body member for movement between said second and first-mentioned positions. This further means may comprise further protrusion means adapted to co-operate with the recess means on the sleeve member in a snap-fit manner.

In addition, the sleeve member may include an annular lip at one end thereof which is arranged to abut said one end of the tubular body member when in said first-mentioned position.

The means on the tubular body member for engaging with the conduit corrugations may comprise at least one projection means which extends inwardly of the bore of the tubular body member. This projection means may extend around the internal surface of the tubular body member, and, in this case, may extend either annularly or helically depending on the configuration of the conduit corrugations.

The tubular body member define a shoulder in its bore against which the end of the conduit is to abut.

Furthermore, the tubular body member may include means at its end remote from said one end for facilitating mounting of the end fitting on a member. This means may comprise a cylindrical projection having an external screw-thread.

The tubular body member and sleeve members are preferably formed of resilient plastics material, for example, nylon. The tubular body member may alternatively be formed of a metal whose characteristics offer suitable flexibility and resilience, for example, aluminium.

An end fitting for a corrugated conduit in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawing which shows the end fitting, partly in cross-section, mounted on one of a flexible corrugated conduit.

The conduit shown in the drawing is of plastics material and is annularly corrugated to impart flexibility and a certain amount of axial compressibility although it is sufficiently rigid in a radial sense to resist crushing. As will be described hereinafter, the fitting may alternatively be used on helically-corrugated conduit.

The end fitting includes a generally tubular body member 10 of resilient plastics material, for example, nylon, having a bore 11 which extends completely therethrough. The tubular body member 10 is formed with an internal annular shoulder 12 intermediate its ends defining one end of a cylindrical recess 14 of the bore 11 which opens at one end 15 of the body 10 and into which the end of the corrugated conduit, referenced 16, is received.

The annular shoulder 12 is of substantially the same size as the overall thickness of the conduit wall such that when the conduit end is inserted into the cylindrical recess 14, with its end abutting the shoulder 12 as shown in the drawing, the bore of the conduit is aligned and continuous with the remainder of the bore 11.

The tubular body member 10 is formed with an integral cylindrical projection 13 at its end remote from the end 15. The projection 13 is externally screw-threaded and adapted to receive a co-operating lock-nut 17 to facilitate mounting of the end fitting in an aperture in a support member (not shown) with the wall of the support member surrounding the aperture being clamped by the lock-nut 17 against a radially-extending surface 18 pro- vided on the tubular body member 1.

An end portion of the tubular body member 10, generally designated 19, is provided with a plurality, for example, six, of axially-extending slots (not visible in the drawing) which open at the end 15 thereof and extend part way along the length of the part of the member 10 which surrounds the cylindrical recess 14 to form a split-collet. The slots, which are spaced at regular intervals around the portion 19, allow the part of the body member adjacent the end 15 to be flexed radially inwards and outwards for purposes which will become apparent.

The external surface of the split collet portion 19 of the body member 10 is tapered inwardly at 21 towards the end 15. The internal surface of the body member 10 adjacent the end 15 is provided with integrally4ormed projection means 22 for engaging with the conduit corrugations and retaining the conduit in the bore 11 of the fitting. In the case where the conduit is annularly corrugated, as shown in the drawing, these means 22 comprise two rows of teeth which project into the cylindrical recess 14 and are arranged to enter respective troughs in adjacent corrugations of the conduit to prevent axial displacement of the conduit.The rows of teeth, which are formed on the fingers of the portion 19 defined by the axially-extending slots and can be regarded as beads made discontinuous by those slots, extend in a circular fashion around the internal surface of the body member 10.

In the case where the fitting is to be used with a conduit having helical corrugations, the conduit engaging and retaining means may be in the form of a discontiriuous bead extending helically around the surface of a section of the cylindrical recess 14 adjacent the end 15.

Although two rows of teeth have been shown in the drawing, the conduit engaging and retaining means may comprise one or more than two rows of teeth.

A generally cylindrical sleeve member 20, also of resilient plastics material, surrounds the portion of the body member including the split-collet portion 19, intermediate the annular shoulder 12 and the end 15. The sleeve member 20 is slidably mounted on the external surface of that portion of the body member for axial displacement relative to the body member and has an internal tapered surface 23 which is arranged to co-operate with the external tapered surface 21 of the portion 19 of the body member 10. In its fully assembled position, as shown in the drawing, the cooperating tapered surfaces 23 and 21 of the sleeve member 20 and portion 19 respectively act to prevent radial expansion, that is, displacement radially outwards, of the split collet portion 19.In this way, the corrugation engaging and retaining means 22 on the tubular body is maintained in engagement with the conduit corrugations and axial displacement of the conduit with respect to the fitting is prevented. The sleeve member 20 is retained in this position on the body member 10 by means of a 'snap-fit' arrangement. This arrangement comprises an annular bead 24 on an outer cylindrical surface of the body member 10 between the portion 19 and a flange 25 defining the surface 18 and a cooperating annular recess 26 on the internal cylindrical surface of the sleeve member 20, the sleeve member 20 being sufficiently flexible and resilient to enable the end 27 thereof to expand and pass over the bead 24 until the recess 26 is located over the bead 24 at which time, the end 27 'snaps' inwardly to its initial, relaxed, configuration.

The snap-fit arrangement need not comprise a continuous bead 24 and recess 26 as shown but may alternatively comprise a circular series of correspondingly spaced protrusions and recesses on the respective opposed surfaces of the body member 10 and sleeve member 20. In such an arrangement, the inner surface of the sleeve member 20 may be formed with axially-extending shallow slots or splines opening at its end 27 and leading to the series of recesses for guiding the sleeve 20 over the body member 10, thereby ensuring correct alignment between the respective series of protrusions and recesses on the body and sleeve members.

The sleeve member 20 is formed with an annular lip 28 at its end which, in its fully assembled position on the body member 10, overlies the end 15 of the body member 10.

To assemble the end fitting on the end of a corrugated conduit, the sleeve member 20 is first slid along the outer surface of the body member 10 towards the end 15 to a position in which the respective tapered surfaces 23 and 21 are out of engagement with one another and limited radial movement of the split collet portion 19 of the body member 10 is allowed. The conduit end is offered to the bore 11 an pushed inwardly. In so doing, the end of the conduit forces the retaining means 22 on the fingers of the portion 19 radially outwards so that the conduit can enter the bore 11. The conduit end is thereafter fed into the cylindrical recess 12, with the retaining means 22 sliding over its outer surface, until it abuts the annular shoulder 12 at which point the retaining means 22 project into the conduit corrugations as shown in the drawing.The sleeve member 20, which is externally knurled to facilitate gripping, is then slid over the surface of the body member 10 towards the flange 25 until the recess 26 snap-fits over the bead 24 with the annular lip 28 abutting the end 15 of the body member 10. During this operation the tapered surface 23 co-operates with the tapered surface 21 on the portion 19 to urge the retaining means 22 inwardly. Engagement between the surfaces 21 and 23 thereafter prevents radial expansion of the split collet portion 19 and maintains the retaining means 22 in the conduit corrugations such that axial displacement of the conduit is inhibited.

To remove the conduit from the end fitting, the sleeve member 20 is slid back to disengage the tapered surfaces 21 and 23 whereupon the conduit can be withdrawn from the bore 11.

It is envisaged that the split collet portion 19 of the body member 10 may be formed such that, in its relaxed condition, the conduit retaining means 22 are positioned out of the path of the conduit end in order that the conduit end may be slid into the cylindrical recess 12 without resistance. The respective co-operating tapered surfaces 21 and 23 may be arranged in these circumstances to urge the conduit retaining means 22 radially inwardly to project into the conduit corrugations upon the sleeve member 20 being fully assembled on the body member 10. To remove the conduit from the end fitting, the sleeve member 20 is slid back to allow the splitcollet portion 19, being resiliently flexible, to spring outwards, thereby disengaging the retaining means 22 from the conduit corrugations.

The sleeve member 20 may include a further annular recess (not shown) formed on its internal surface and axially displaced from the recess 26 towards its end 27 which serves to co-operate in a snap-fit manner with the annular bead 24 on the body member 10 to retain the sleeve member 20 on the body member 10 in a second position prior to the sleeve member 20 being fully assembled on the body member 10 such that the sleeve member 20 is captively mounted on the body member 10 for sliding movement between the first and second positions. In the second position, the respective tapered surfaces 21 and 23 on the body and sleeve members 10 and 20 are displaced with respect to one another to allow limited radial expansion of the split collet portion 19 of the body member 10.In an alternative arrangement for retaining the sleeve member 20 on the body member 10 prior to it being slidably moved to its final assembly position, one or more pins may be formed on the external cylindrical surface of the body member 10 away from the bead 24 and towards the end 15 which are arranged to engage with the recess 26 in a snap-fit manner so as to retain the sleeve member in its second position. In this case, the sleeve member 20 would include a further annular recess arranged to lie over and accommodate the one or more pips when the sleeve member is slid into its first, fully assembled, position.

It may in some circumstances be desirable to prevent the ingress of moisture, dust, or the like into the bore of the conduit, and to this end sealing means may be disposed between the conduit and the inner bore of the body member 10. This sealing means may take the form of a rubber sealing ring which is either located around the conduit adjacent its end and sealingly engaging in compression with the surfaces of the conduit and the recess 14 of the body member 10, or disposed between the end of the conduit and the shoulder 12.

It is envisaged that the tubular body member 10 may be formed with a V-shape groove (not shown) extending around its periphery adjacent the inner end of the split collet portion 19, to impart increased flexibility to the fingers of the portion 19.

It is also envisaged that the body member may be formed from a suitably flexible and resilient metallic material such as aluminium instead of plastics.

It will be apparent from the above that the end fitting is particularly simple and convenient to use. Following insertion of a conduit end into its bore 11, all that is necessary for the end fitting to be mounted securely on the conduit end is that the sleeve member 20 be slid axially forward over the body member 10 until it snap-fits on the body member 10.

Similarly, it is only necessary to slide the sleeve member 20 axially back over the body member 10 away from its snap-fit position to permit removal of the end fitting from the conduit.

Claims

1. An end fitting for a corrugated conduit comprising a generally tubular body member having a bore in which an end of the conduit is to be received, a portion of the tubular body member having means thereon for engaging with the conduit corrugations to retain the conduit in said bore and being radially displaceable to facilitate insertion of the conduit end into the bore from one end thereof, and a sleeve member which extends around the outer surface of the tubular body member, wherein the sleeve member is adapted for movement axially of the tubular body member to a position in which the sleeve member is arranged to cooperate with the tubular body member to inhibit radial displacement of said portion of the tubular body member and thereby maintain said engagement means in engagement with the conduit corrugations, and wherein the sleeve member is retained on the tubular body member in said position by means of a snap-fit arrangement.

2. An end fitting according to Claim 1, wherein said portion of the body member comprises a region of the body member adjacent to, and including, said one end of the body member.

3. An end fitting according to Claim 2, wherein the body member is provided with a plurality of slots which extend axially of the body member from said one end along a length of the body member defining said radially-displaceable portion to permit radial flexing of said portion.

4. An end fitting according to Claim 3, wherein the peripheral surface of the body member adjacent the inner end of said slots is provided with a groove extending therearound to increase flexibility of said portion.

5. An end fitting according to any one of the preceding claims, wherein the sleeve member and the body member include respective tapered surfaces which are adapted to cooperate with one another when the sleeve member is moved axially of the body member to said position to inhibit radial movement of said portion of the body member.

6. An end fitting according to Claim 5, wherein the tapered surface of the body member is formed on the external surface of said portion of the body member.

7. An end fitting according to any one of the preceding claims, wherein the snap-fit arrangement comprises respective cooperating protrusion and recess means on the sleeve and body members.

8. An end fitting according to Claim 7, wherein one of the sleeve and body members includes an annular protrusion and the other of said members includes a cooperating annular recess.

9. An end fitting according to any one of the preceding claims, wherein the sleeve member is mounted on the body member for slidable movement between a second position in which limited radial displacement of said portion of the body member is permitted and said first-mentioned position.

10. An end fitting according to Claim 9, wherein the body member includes means for engaging with the sleeve member in said second position such that the sleeve member is captively mounted on the body member for movement between said second and first-mentioned positions.

11. An end fitting according to Claim 10 together with Claim 7 or Claim 8, wherein said means for engaging with the sleeve member in said second position comprises further protrusion means adapted to cooperate with the recess means on the sleeve member in a snap-fit manner.

12. An end fitting according to any one of the preceding claims, wherein the sleeve member includes an annular lip at one end thereof which is arranged to overlie said one end of the body member when in said firstmentioned position.

13. An end fitting according to any one of the preceding claims, wherein the means on the body member for engaging with the conduit corrugations comprises at least one projection means extending inwardly of the bore of the body member and arranged to enter a respective trough of the corrugated conduit.

14. An end fitting according to Claim 13, wherein the or each projection means extends around the internal surface of the body member.

15. An end fitting according to Claim 13 or Claim 14, wherein the at least one projection means is at one end of said portion of the body member.

16. An end fitting according to any one of the preceding claims, wherein the body member defines a shoulder in its bore against which the end of the conduit is to abut.

17. An end fitting according to any one of the preceding claims, wherein the body member includes means at its end remote from said one end for facilitating mounting of the end fitting on a member.

18. An end fitting according to Claim 17, wherein said mounting facilitating means comprises a screw-threaded cylindrical projection.

19. An end fitting according to any one of the preceding claims, including sealing means for sealingly cooperating between the bore of the body member and a conduit inserted into said bore.

20. An end fitting according to any one of the preceding claims, wherein the body member is formed of flexible resilient material.

21. An end fitting according to Claim 20, wherein the body member comprises resilient plastics material.

22. An end fitting according to any one of the preceding claims, wherein the sleeve member comprises resilient plastics material.

23. An end fitting substantially as hereinbefore described with reference to the accompanying drawing.