GB2347799A - A boot for fitting about a longitudinally extending member - Google Patents

Abstract

A boot for fitting about a longitudinally extending member (34) such as a cable, the boot made from a resilient sheet (2) of material having opposing side edges (4, 6) and an unstretched width that is insufficient for the side edges (4, 6) to abut when the sheet (2) is wrapped around a connection zone of the longitudinally extending member (34). A stretching means (30) is removably fittable to the resilient sheet (2) which results in the resilient sheet having a stretched width that is sufficient for the side edges (4, 6) to abut when the sheet (2) is wrapped around the connection zone. A clasp (38) grips the resilient sheet (2) along the side edges (4, 6) whereby a tubular shape is maintained. The stretching means (30) may comprise plate members which are insertable into cavities in the resilient sheet (2) and removable therefrom by pulling members (40) to permit the resilient sheet (2) to resiliently contract onto the connection zone.

Description

A BOOT FOR FITTING ABOUT A LONGITUDINALLY EXTENDING MEMBER This invention relates generally to joint coverings, such as for splices in the electrical cables, and in particular, to providing a covering along a longitudinally extending member without access to the ends thereof.

There is a common need to form splices or taps of cables in the field. These cables may be dispose in underground conduits or overhead conduits in, for example, an industrial facility. The cables may be for power or communication lines. It is not usually necessary to completely sever the entire cable.

Normally, once these splices or taps have been formed, it is known to cover the connection area. This prevents the entrance of contamination into the zone of the joint or splice and also provides structural integrity to the cable. One common solution is to simply wrap tape or a band around the connection area. This however is costly in both time and materials and is sometimes difficult to accomplis due to the location of the associated splice or tap. Varions attempts to solve this problem have been made in the past.

US 3, 187, 090 discloses a one-piece unitary boot of flexible material that is in impervious to moisture and specially constructed to be applied and removed from cable joints. The boot is a flexible sheet of material having a longitudinally extending cavity that is established by a fluid-tight seam formed, for example by, a slide fastener. In use, once the splice or tap has been made, the boot is fitted about the connection zone and the slide fastener is actuated, thereby enclosing the connection zone. The ends of the boot through which the cable extends are then sealed by fittings in combination with taping. A problem with this structure is that access to ends of the cable is required so the fittings may be placed thereupon, additional steps are required for the taping of the ends and sealing is dependent upon the quality of the taping.

In US 3, 946, 480 a"cold shrink"device is disclosed that utilises a laterally expandable resilient tubular member capable of being expanded and subsequently contracte onto a member dispose therein. This device comprises the laterally expandable resilient sleeve and an apparats for expanding the sleeve. The sleeve, in its expanded form with the apparats therein, is fitted over an end of a cable. A splice or tap is then formed in the cable and the apparats is moved over this connection zone. Once properly positioned, the apparats for expanding the resilient tubular member is removed and the tubular member contracts upon the connection zone, thereby forming the desired covering. A problem with this device is that the resilient sleeve is tubular in form so it requires access to a free end of the cable to be fitted thereupon.

US 4, 283, 239 discloses a"heat shrink"covering which could be used in this application. Here a wrap around heat recoverable sheet may be placed over a connection zone once it is formed. The heat recoverable sheet inclues rails over which a channel is placed once the sheet is wrapped around the cable. With the heat recoverable sheet now joined into a tubular structure, heat is applied to cause recovery, thereby forming the sheet closely to the contours of the cable and the connection zone therein. A problem with this apparats is that the heating equipment needed to affect the covering often is cumbersome and may pose a safety concern, as these cables are often in the vicinity of gas lines or other sensitive equipment.

Therefore it is an object of this invention to provide a covering that can be fitted about a connection zone, where a cable splice or tap is made, without need to access a cable end and without the need to apply heat or other stimulant to the covering. It is a further object of this invention to provide a simple and reliable covering that requires minimal operator skill.

It is still yet another object of this invention to provide a covering that is economical to manufacture and apply.

These and other objects are accomplished by providing a covering envelope as set out in claim 1. The covering boot disclosed herein generally features a resilient sheet of material that has oppositely dispose side edges that are constructed to be joined together such that the sheet assumes a tubular shape. The sheet has a first unstretched size that is insufficient for the oppositely dispose side edges to be joined together when the sheet is wrapped around a longitudinally extending member and a second stretched size that is sufficient for the oppositely dispose side edges to be joined together when the sheet is wrapped around the longitudinally extending member. Further included is a removable stretching member that co-operates with the sheet to bring the sheet into a stretched size prior to joining the opposing sides. The stretching member being removable so that as the sheet resiles towards the unstretched size, the sheet closely conforms to the longitudinally extending member now therein.

It is an avantage of this invention that it can be fitted around any connection zone in a cable without access to the ends of the cable. It is another avantage of this invention that due to the resilience of the sheet, a non-uniform connection zone can be accommodated. It is yet another avantage of this invention that because the seal is dependent upon the resilience of the sheet and not an operator process, sealing integrity is assure. It is still yet another avantage of this invention that the covering envelope can be economically produced.

The invention will now be described by way of example with reference to the drawings wherein ; Figure 1 is an upper perspective view of a resilient sheet according to the present invention in a first unstretched size ; Figure 2 is an upper perspective view of the under side of the resilient sheet of figure 1 in a second stretched size with the stretching member viewable therein; Figure 3 is an upper perspective view showing a covering envelope according to the present invention in a stretched form about a tap ; Figure 4 is an upper perspective view of the covering envelope according to the present invention as shown in figure 3 with the stretching members removed.

With reference now to figure 1, a resilient sheet of material is shown generally at 2. The resilient sheet of material 2 is formed of a rubber-like material. The resilient sheet 2 has a natural width (A) and a length (B). The resilient sheet of material 2 has opposing side edges 4, 6, an outer surface 8 and an inner surface 10.

The opposing side edges 4, 6 include a complementary tongue 12 and groove 14 formed therein. Additionally, along each opposing side edge 4, 6 are flanges 16 they are dispose on the outer surface 8 of the resilient sheet 2.

The resilient sheet 2 is formed of plurality of longitudinally extending tubular portions 18 separated from one another by webs 20. The tubular portions 18 include outer walls 22 and inner walls 24 that when combine with the webs 20 define open-ended longitudinally extending cavities 26 therein. The cavities 26 extend the entire length (B) of the resilient sheet 2. Additionally, corresponding to each web 20 and along the outer surface 8 of the resilient sheet 2 are longitudinally extending flexing ribs 28 that enable the resilient sheet 2 to maintain structural integrity upon jolnIng of the opposing sides 4, 6. The longitudinally extending configuration of the resilient sheet 2 enables the resilient sheet to be easily and economically manufactured through an extrusion process.

However, other manufacturing techniques may be used.

With reference now to figure 2, the resilient sheet 2 is shown having a stretch width (A'). Stretch width (A') is accomplished by inserting stretching members 30 into the longitudinally extending cavities 26. The stretching members 30 have a width (C) greater than the distance between adjacent webs 20 of a section 18. As a result of inserting the stretching member 30 into the cavity 26, the upper and lower walls 22, 24 are stretched, thereby contributing to the expansion of a natural unstretched width (A) towards the stretched width (A'). The stretching members 30 may be manufactured from any convenient material, such as a metal or plastic with the desired goal of minimizing the co-efficient of friction between the stretching member 30 and the resilient sheet 2, thereby minimising forces necessary to insert or remove the stretching member 30 from the cavities 26. The stretching members 30 also include holes 32 for removing the stretching member (as described below).

With reference now to figure 3, a longitudinally extending cable 34 is shown. A tap cable 36 is joined with the longitudinally extending cable 34. As is normally the case, in order to affect the tap, it has not been necessary to completely sever the longitudinally extending cable 34, so it is not possible to access an end thereof. The connection zone formed where the tap occurs is dispose within the now stretched resilient sheet 2, with the stretching members 30 therein, that has been fitted about the connection zone by wrapping the resilient sheet 2 in the direction of arrows (Z). The opposing side edges 4, 6 are butted together such that the tongue 12 is received within the groove 14. Then a clasp 38 is slid along the flange portion 16 of each of the opposing sides 4, 6 such that the opposing sides 4, 6 are held together. The clasp 38 can be any appropriate material, such as metal or plastic, that is strong and flexible enough to hold the side edges together once the stretching member 30 is removed. It may also be possible to integrally form the clasp 38 with the resilient sheet 2. The tongue 12 being received within the groove 14 assures the integrity of the seal. At this point, the resilient sheet 2 has a tubular shape that is dispose about the connection zone. By the use of a pulling member 40 that is received within the holes 32 of a stretching member 30, the stretching members 30 are removed. As the stretching members 30 are removed, the walls 22, 24 of each section 18 resile, thereby reducing the size of the now tubular resilient sheet 2 towards its unstretched dimension.

With reference now to figure 4, all of the stretching members 30 have been removed from the cavities 26 and the resilient sheet 2 has resiled toward the unstretched configuration, thereby tightly encompassing the connection zone. It may be desirable to form a potting material 42 or some other material about the cables 34, 36 in order improve seal integrity.

As can be seen, it is possible to form the sheet 2 around a connection zone having a non-uniform shape by taking avantage of the resiliency of the sheet 2.

Therefore, advantageously a sealing envelope is provided by way of a resilient sheet that has an unstretched width insufficient to be wrapped around a connection zone which can be pre-stretched such that the opposing side edges will join together when the resilient sheet 2 is wrapped around the connection zone and upon removal of the stretching member used to pre-stretch the sheet 2, the resilient sheet resiles to fit about the connection zone.

Claims (7)

CLAIMS:

1. A boot for fitting about a longitudinally extending member, such as a cable, the boot comprising a resilient sheet of material having opposing side edges ; the resilient sheet having an unstretched width between the opposing side edges that is insufficient for the side edges to abut when the sheet is wrapped around a connection zone of the longitudinally extending member ; a stretching means or member that is removably fittable to the resilient sheet and when the stretching means or member is attache to the resilient sheet, the resilient sheet is resiliently stretched to a stretched width between the opposing side edges that is sufficient for the side edges to abut when the sheet is wrapped around the connection zone ; and engagement means for maintaining the resilient sheet in a tubular shape.

2. The boot of claim 1 wherein the engagement means comprises a clasp to grip the resilient sheet along the side edges thereof when the side edges abut, whereby the tubular shape is maintained.

3. The boot of claim 2 wherein the side edges inclues a flange engageable by the clasp.

4. The boot of claim 1, 2 or 3 wherein the side edges include complementary features to establish an abutting seal therebetween.

5. The boot of any preceding claim wherein the stretching means or member is made up of multiple pieces.

6. The boot of any preceding claim wherein the resilient sheet inclues multiple longitudinally extending tubular portions separated from one another by webs and the stretching means or member inclues multiple plates insertable into the tubular portions.

7. A boot substantially as herein described with reference to the accompanying drawings.