GB2305553A

GB2305553A - Electrical conductor enclosing apparatus using polyurethane foam

Info

Publication number: GB2305553A
Application number: GB9618507A
Authority: GB
Inventors: David Alan Croton
Original assignee: Sicame Electrical Developments Ltd
Current assignee: Sicame Electrical Developments Ltd
Priority date: 1995-09-21
Filing date: 1996-09-05
Publication date: 1997-04-09
Also published as: GB9618507D0; GB9519287D0

Abstract

The invention which is the subject of this application relates to apparatus for enclosing the end of an electrical conductor or the joint between at least two electrical conductor cables to prevent damage to the conductors and to prevent the ingress of water, contaminants, and to resist impact thereon. The current apparatus of the invention provides a shell which is placed around the conductors to form a cavity and, into the cavity is formed a foamable material to a sufficient volume to fill the said cavity with the foam material at a density which allows the same to resist impact, avoid contamination of the conductor and prevent the ingress of water. The use of the foamable material in the shell allows the apparatus to be lighter, and the mixing of the foamable material to a required form to be predicted and determined by the apparatus rather than the operator, as the container in which the foamable material is held, prior to the same being mixed, can contain at least two compartments, one of which contains a hardener and the other of which contains a resin and also a propellent.

Description

Electrical Conductor Enclosing Apparatus The invention which is the subject of this application relates to apparatus for enclosing the end of an electrical conductor or the joint between at least two electrical conductor cables. The apparatus is provided to prevent damage to the end of the electrical conductor cable or the joint and to prevent the ingress of water, contaminants and to resist impact thereon.

Conventionally the apparatus comprises a shell with a cavity and an inlet into the cavity. The cavity surrounds the cable end or joint and is filled with a polyurethane or similar resin. When entered into the cavity, the resin is in a liquid form but, with the hardener added, the liquid solidifies to form a solid high density material.

The conventional use of liquid resin has several disadvantages, not least of which is the high expense of the material and, when one considers that one standard regional electricity company can use 200,000 litres of the resin each year, the cost is an important factor.

Another factor is the weight of the completed apparatus as the resin is very heavy. Furthermore, the resin and hardener are not always mixed correctly and therefore the properties of the resin cannot always be accurately predicted. Another problem is with regard to the safety of the resin hardening material which in some instances can be an isocyanate and this can cause problems with the increasingly stringent Health and Safety at Work Provisions.

The aim of the present invention is to provide apparatus which can include filling material other than conventional resins to be used and to ensure that the apparatus is of a form such that the material is used in the correct form and has the desired effect in relation to the cable conductor and/or joint.

In a first aspect of the invention there is provided apparatus for enclosing an end of a conductor or a joint between electrical conductors, said apparatus comprising a shell for placing around the conductors having at least one inlet for the introduction into the cavity formed by the shell of a foamable material to surround the conductors.

Typically the foamable material is a polyurethane foam. Preferably the apparatus can include as part thereof a foam container which contains, in separate compartments, a resin and a hardener and also a propellant which is preferably butane. The container is provided with means to allow the hardener to be introduced into the resin in the container prior to dispensation of the material from the container by actuation of the propellant. In this format, when the hardener and resin are mixed, the foamable material formed is required to be expelled from the container into the shell immediately after the hardener and resin have been mixed together by shaking the container.

By providing the hardener and resin to be premixed, the requirement to add moisture to the foamable material is removed.

In one embodiment the foamable material is iso foam mounting foam 4539 and 4545 which are two component polyurethane foams in an aerosol container with HFC 152 as the propellent. The container contains two components which are required to be mixed immediately before dispensation.

In a preferred embodiment, the volume of foamable material which is required to be introduced into the cavity shell is contained within one, two or any multiple thereof of containers such that the operator filling the cavity of the shell can ensure that when the contents of the designated number of containers has been introduced into the cavity the same is full with the required volume of foamable material.

In a preferred embodiment, the volume of foamable material which is required to be introduced into the cavity is contained within one container such that the operator filling the cavity can ensure that when the contents of the one container have been introduced into the cavity the same is full with the required volume of foamable material.

In one embodiment, the shell is provided in a two part form with the join between the parts along the longitudinal axis of the same. In one embodiment the shell is provided with at least one vent to allow the exhaust of air from the cavity formed therein when the foamable material is introduced. This allows a reduction in the air which is trapped in the foamable material thereby increasing the density of the same and improving the performance of the same in tests.

Preferably there is provided a plurality of air vents to increase the exhaust of air.

In one preferred embodiment the vent is provided in the form of a valve which allows the exhaust of air but, which when contacted by the foamable material is moved to a closed position. A vent of this type also acts as a means for indicating that the shell is filled with a foamable material to the required extent.

Typically the shell cavity is filled with foamable material from one side of the shell and the vents are provided on the opposite side of the shell. By using the foamable material according to the present invention, significantly less resin material is used as the volume of the resin when in a foamed state is significantly greater than when used in a liquid state as in the conventional form.

In a further aspect of the invention there is provided apparatus for enclosing a joint between at least two electrical conductor cables, said apparatus comprising a shell forming a cavity around the joint for the introduction of a foamable material therein to fill the same and wherein said shell is provided with a manifold for the introduction of foamable material into the cavity through a plurality of spaced parts.

In one embodiment the parts are linearly spaced along the shell and interconnected via a channel or channels to an inlet on the surface of the shell to which the outlet of the foamable material container can be connected. In an alternative embodiment the ports are linearly spaced and radially spaced around at least a portion of the shell.

In one embodiment the ports inlets are circular in shape or, alternatively, the ports can be shaped to encourage the flow of foamable material. Furthermore the size of the ports increase the further removed from the point of introduction of the foamable material into the shell to ensure that the foamable material enters the peripheral parts of the shell also.

Typically the shell is formed from two parts which are joined together to form the cavity by clips.

In one embodiment, the sealing faces between the shell parts are provided with means to prevent escape of the foamable material between the same.

Preferably the manifold, ports, inlet and vents are formed along the sealing faces of the shell parts thereby reducing the cost of moulding the shell parts.

Typically the shell parts are manufactured from plastics material which is of sufficient thickness to meet the impact requirements when the shell cavity is filled with the foamable material.

The current invention provides apparatus for enclosing a joint between cable conductors or an end of a conductor comprising a shell around the conductor or conductors and defining a cavity therein, said cavity filled with a foamable material to insulate an protect the conductor end and/or joint.

In a further aspect of the invention there is provided a method for enclosing the end of an electrical conductor or joint between at least two electrical conductor cables, said method comprising the steps of placing a shell around said conductor and/or joint to define a cavity and in which said conductor and/or joint lies connecting a container of foamable material to at least one inlet provided in the shell and introducing foamable material from the container into the shell cavity to fill same, and continuing to introduce foamable material until the cavity is filled with the same to the required density.

In a preferred embodiment, the volume of the cavity is known and the volume of foamable material in a container is known such that a predesignated number of containers can be connected to the shell to introduce a predesignated volume of foamable material to fill the cavity or, alternatively, a single container is provided with a sufficient quantity of foamable material to fill the cavity of the shell with the required volume.

Specific embodiments of the invention are now described with reference to the accompanying drawings wherein; Figure 1 illustrates the apparatus in perspective, enclosing a conductive cable joint; Figure 2 illustrates the shell in plan from the base of the same according to the invention; Figure 3 illustrates a sectional end view along line A-A of Figure 1; Figure 4 illustrates a plan view of one shell part; Figure 5 illustrates a detailed view of the sealing faces of the shell parts; Figure 6 illustrates in detail one embodiment of the inlets of the manifold; Figure 7 illustrates in detail a second embodiment of the inlets of the manifold; and Figures 8A and 8B illustrate alternative manifold arrangements in end elevation.

Referring firstly to Figure 1 there is shown apparatus for enclosing a joint between cable conductors 2, 4 which are provided to carry, for example, electricity supplies to domestic premises. The apparatus comprises a shell 8 formed of parts 10, 12 held together to form a cavity around a joint and said cavity is filled with a foamable material 14 which is hardened. The foamable material is dispensed from a container or series of containers which are attached to inlet 16 and relatively soon after application, the foamable material hardens. Indeed, if the foamable material is premixed in the container there can be only a 15 minute time period from mixing in which to inject the material into the cavity before the material begins to harden.

Referring now to Figure 2 there is shown one embodiment of the shells 8 formed at the parts 10 and 12. In this embodiment the inlet 16 is provided in connection with a manifold 18 formed in the shell at the sealing faces 20, 22 of the shell parts. The manifold allows the inlet 16 to be connected to a plurality of spaced ports 24 into the cavity, said ports spaced at regular intervals along the length of the shell to allow the introduction of the foamable material at points along the shell rather than at one particular point. This is found to improve the eveness of spread of the foamable material throughout the shell and also to encourage the exhaust of air through the vents 28 which are shown in Figures 3 and 4.

Both Figures 3 and 4 illustrate the positioning of the vents opposite the position of the ports 24 to ensure that all of the air is exhausted.

The shell 8 is also provided with apertures 30, 32 at each end through which the conductor cables enter the shell and these apertures and the sealing faces 20, 22 of the shell parts are formed to minimize the escape of the foamable material through the same.

One such arrangement of the sealing faces 20, 22 is shown in Figure 5 wherein a sealing strip 34 is located between the faces, said strip preferably having layers of adhesive to allow the same to be applied to the faces and the faces are clamped in position by a series of spring clips 36.

Figure 6 and 7 show details of the inlets 24. In Figure 6 it is shown that the size of the ports 24 can be increased the further removed they are from the inlet 16. The increase in size ensures that although there will be less pressure on the foamable material as it is further removed from the point of entry, the material will still enter into the cavity. Figure 7 illustrates that the ports 24 can be shaped to encourage the flow of material and these ports can again be increased in size.

Figures 8A and 8B illustrate alternative arrangements for the manifold where the manifold is provided as part of one of the shell parts rather than being formed betwen the sealing faces of the two parts.

In whichever embodiment the apparatus of the current invention has considerable advantages over the conventional apparatus, in terms of cost as less material is used to fill the shell cavity, in terms of time and also the opportunity for error is reduced as the operator is not required to mix materials and, as the materials are provided in their optimum quantities so the performance of the apparatus is improved over conventional means.

Claims

1. Apparatus for enclosing an end of a conductor or a joint between electrical conductors, said apparatus comprising a shell for placing around the conductors having at least one inlet for the introduction into the cavity formed by the shell of a foamable material to surround the conductors.

2. Apparatus according to Claim 1 wherein the foamable material is a polyurethane foam.

3. Apparatus according to Claim 1 wherein the apparatus further includes a foam container which contains, in separate compartments, a resin and a hardener and a propellent.

4. Apparatus according to Claim 3 wherein the container is provided with means to allow the hardener to be introduced into the resin in the container prior to dispensation of the material from the container by actuation of the propellent.

5. Apparatus according to Claim 4 wherein when the hardener and resin are mixed the foamable material is required to be expelled from the container into the shell within a pre-set time limit.

6. Apparatus according to any of the preceding claims wherein the volume of foamable material which is required to be introduced into the cavity shell is contained within one, two or any multiple thereof of containers.

7. Apparatus according to Claim 6 wherein the volume of foamable material required to be introduced into the cavity is contained within one container.

8. Apparatus according to Claim 1 wherein the shell is provided in a two-part form with a join between the parts along the longitudinal axis of the same.

9. Apparatus according to Claim 1 wherein the shell is provided with at least one vent to allow the

exhausts air from the cavity formed therein when the foamable material is introduced.

10. Apparatus according to Claim 9 wherein the vent is provided in the form of a valve which allows the

exhausts air but, which when contacted by the foamable material, is moved to a closed position.

11. Apparatus according to Claim 10 wherein the vent in a closed position acts as an indicating means to show that the shell is filled with foamable material to the required extent.

12. Apparatus for enclosing a joint between at least two electrical conductor cables, said apparatus comprising a shell forming a cavity around the joint of the cables for the introduction of a foamable material therein to fill the same, and wherein said shell is provided with a manifold for the introduction of foamable material into the cavity through a plurality of spaced ports.

13. Apparatus according to Claim 12 wherein the ports are linearly spaced along the shell and interconnected via a channel or channels to an inlet on the surface of the shell to which an outlet of a foamable material container can be connected.

14. Apparatus according to Claim 13 wherein the ports are linearly and radially spaced around at least a portion of the shell.

15. Apparatus according to Claim 13 wherein the ports are increased in size and further removed from the inlet for the foamable material.

16. A method for enclosing the end of an electrical conductor or joint between at least two electrical conductors, said method comprising the steps of placing a shell around said conductor and/or joint to define a cavity and in which said conductor and/or joint lies; connecting a container of foamable material to at least one inlet provided in the shell and introducing foamable material from the container into the shell cavity to fill same.

17. A method according to Claim 16 wherein the volume of the cavity is known and the volume of foamable material in the container is known such that the pre-designated number of containers can be connected to the shell to introduce a predesignated volume of foamable material to fill the cavity.