GB2304469A

GB2304469A - Electrical apparatus enclosure

Info

Publication number: GB2304469A
Application number: GB9524765A
Authority: GB
Inventors: Stuart Frank Copping; Michael Richard Taylor
Original assignee: Malcoe Precision Fabrications Ltd
Current assignee: Malcoe Precision Fabrications Ltd
Priority date: 1995-08-16
Filing date: 1995-12-04
Publication date: 1997-03-19
Anticipated expiration: 2015-12-04
Also published as: GB9524765D0; GB2304467A; GB9516769D0; GB2304469B

Description

1 ELECTRICAL APPARATUS ENCLOSURE is 2304469

This invention relates to the field of electrical apparatus enclosures.

It is known to provide electrical apparatus enclosures for housing electrical equipment, such as telephone junction/switching equipment and traffic signalling equipment, in outdoor locations, typically by the side of a road. Such an environment is harsh and the enclosures must provide a high degree of protection for what can be expensive and sensitive electrical apparatus. The enclosures must protect their contents from damage by moisture or dust penetrating the enclosures, temperatures that are too high or too low and similar environmental factors consequential upon their exposed location.

Another aspect of the protection that must be provided by the electrical apparatus enclosures is protection against damage by vandals or other malicious persons. The enclosures may be fitted with security locks that resist picking but must also be made sufficiently mechanically strong that they can resist direct attempts to breach their security, such as in the locks, hinges or doors by forcing with a lever.

According to the invention there is provided an electrical apparatus enclosure comprising:

C an enclosure housing: a side door mounted in a side opening in said enclosure housing and hinged about a side door axis; and a lid mounted on said enclosure housing and hinged about a lid axis, a distal edge of said lid from said lid axis abutting a top edge of said side door when said side door and said lid are both shut; wherein said enclosure housing has a housing groove facing a bottom edge of said side door and said lid has a lid groove facing said top edge of said side door, such that when said side door and said lid are both shut said bottom edge of said side door is held within said housing groove and said top edge of said side door is held within said lid groove, and when said lid is open releasing said top edge of said side door from said lid groove, said,.side door may be moved upwards parallel to said side door axis to release said bottom edge of said side door from said housing groove thereby freeing said side door to pivot open about said side door axis.

2 The arrangement by which the side door sits within grooves when it is shut C makes it extremely difficult to lever open the door since this would involve a major distortion of the entire housing structure. In contrast, a conventional lock would only require the breaking of the lock bolt to force open the door. Whilst the lid is still vulnerable to being forced open, the lid can be made smaller, since the main access will be through the doors, and so a less obvious target. Forcing open the side door would be the obvious starting point since it is the largest potential opening into the enclosure and would normally be considered to be the weakest link in the security of the enclosure.

In preferred embodiments of the invention, when said side door is shut, a hinged edge of said side door abuts and lies behind a hinge lip in said housing.

Placing the edge of the side door which is hinged behind a lip in the housing makes it more difficult to lever open the door by attacking the hinge. This arrangement also makes the weather and RE sealing properties of the door greater.

In order to assist in the opening of the enclosure, preferred embodiments of the invention provide a resilient means disposed between said housing and said side door for urging said side door upwards along said side door axis when said lid is open.

It will be appreciated that the resilient means could take many forms (e. g. a leaf spring or a block), but in preferred embodiments of the invention said side door is hinged about a rod running between said housing and said side door and said resilient means comprises a coil spring disposed around said rod between said housing and said door.

This arrangement provides a straightforward and reliable assistance to the disengagement of the side door from the housing groove and also provides an arrangement by which the hinged edge of the side door can sit behind a hinge lip in the side of the housing.

The housing groove and the lid groove also provide opportunities for improving other performance characteristics of the enclosure. One such opportunity that is exploited in preferred embodiments of the invention is that said housing groove and said lid groove contain weather and radio frequency interference seals that are pushed into contact with said side door when said side door and said lid are shut.

Placing weather and FRI seals within the grooves ensures a particularly firm 3 contact between the seals and the side door that improves their performance. With a more normal arrangement, warping of the door can cause a weakening in the contact between these seals and the door that compromises their performance.

In order to provide a larger opening for access without unduly compromising security, preferred embodiments of the invention comprise two of said side doors within said side opening and hinged about opposite edges of said side opening, said two side doors having distal. edges from said side door axes that abut when said two side doors are closed, said distal edges of said two side doors have complementary formations that engage each other when said two side doors are closed.

The security of the closing of the lid can be enhanced by providing a selflocking lock mechanism between said lid and said housing such that said lid is locked closed when it is pushed shut.

Such self-locking mechanisms are known in uses such as locking car luggage compartments and typically provide a very high degree of security.

In order to improve the strength of the lid and housing to make the forcing open of the lid more difficult it is preferred that said lid and said housing each include CP an end casting at each end of said lid axis.

The presence of a casting at each end of the lid strengthens the ends of the lid and so makes it advantageous to include a catch extending between said lid and said 0 ?0 housing at each end of said lid.

The lock cylinder is the only portion of the locking mechanism of this enclosure that needs to be accessible from the exterior of the enclosure. In order to improve the security of this arrangement it is preferred that any lock cylinder is disposed in one of the end castings.

With an arrangement in which the lock cylinder is included within a casting it is convenient to provide that said lock cylinder is connected to other parts of said self-locking lock mechanism via a sheathed cable.

A cable link between the lock cylinder and the other parts of the selflocking lock mechanism provides a high degree of flexibility in the location of the other parts of the self-locking lock mechanism.

An embodiment of the invention will now be described, by way of example only, With reference to the accompanying drawings in which:

4 Figure 1 illustrates an electrical apparatus enclosure in accordance with one embodiment of the present invention; Figure 2 illustrates the principal of construction of a double-walled panel of the enclosure of Figure 1; Figure 3 illustrates the fixing used between double-walled panels of the embodiment of Figure 1; Figure 4 illustrates the principal upon which the side door of the enclosure of Figure 1 operates; and Figure 5 illustrates the self-locking lock mechanism and lock cylinder arrangement.

Figure 1 shows an exploded view of an electrical apparatus enclosure 2 having a carcass construction of double-walled panels that together form a housing (except for the lid and the side doors). An end wall of the enclosure 2 comprises an outer skin 4 and an inner skin 6. The outer skin 4 and the inner skin 6 are made of sheet aluminium or aluminium alloy pressed to the required shape. The outer skin 4 and the inner skin 6 include only simple curves in one direction making their fabrication easier. A metal casting 8 (i.e. aluminium alloy) is provided at the top end of the panel and a metal casting 10 is provided at the bottom end of the panel. The shape of the outer skin 4 is formed so as to be held captive by respective portions 12 of the top casting 8 and the bottom casting 10.

The top casting 8 includes a number of cabling entry ports 14 that may be closed off with a blanking plate 16 if they are not required. The cabling entry points 14 lead to an upper roof space 18 of the enclosure 2 that it positioned beneath a hinged lid 20. The hinged lid 20 includes a casting 22 at each end. The castings 8 at the top of the end panels 4 include a lock cylinder that will be discussed later in connection with Figure 5.

The enclosure 2 incorporates two double-walled side doors 24 that are hinged about a vertical access (side door access). When shut, the side doors 24 may be pushed down against the action of a coil spring 27 to sit within a groove 26 in the bottom of the housing. When the side doors 24 are open, the springs 27 hold the side doors 24 up so that they do not foul the groove 26 and restrict opening.

The edges of the side doors 24 that are furthest from the hinged edge include -)o 3 complementary formations (i.e. a V-shaped protrusion and a V-shaped groove) that inter-engage when the two side doors 24 are both shut so as to resist the forcing apart of the two side doors 24.

The enclosure 2 has a carcass construction whereby it is assembled from and may be disassembled to individual, substantially flat panels, e.g. end panels, lid, doors, back, bottom, etc.

Each of the double-walled panels of the enclosure 2 of Figure I is filled with foam that is introduced between the panel walls and then sets. This foam serves to enhance the security offered by the panel and also increases its strength, insulation and noise blocking properties. Figure 2 schematically illustrates the production of such a panel.

An outer skin 4 is formed by a pressing process from flat sheet aluminium alloy. The outer skin 4 is then placed in a jig (not shown) and an electromagnetic radiation screening mesh 30 (this may be formed embedded with a sheet of backing material such as rubber or plastic or could be a continuous thin metal sheet) is clipped into place within it and then followed by the inner wall 6 (the screening mesh '30 is optional and may be omitted). At this stage, the assembly has relatively little strength.

The open ends of the double-walled panels are then closed with temporary plugs associated with the jig (or the perminant castings) and a predetermined volume of foam is injected using a system such as that designed for packaging and sold as Instapak by Sealed Air Limited of Northants, England. The quantity of this foam that is injected may be empirically determined such that when it has expanded and sets it fills substantially all of the volume between the outer wall and the inner wall without excessive overflow. The set foam 32 flows around the mesh '30 and so embeds this securely in position. The non-compressibility of the foam 32 also serves to hold the inner skin 6 in an interlocking and abutting relationship with the outer skin 4. The double-walled and foam filled panel has a high degree of strength and offers good security.

The electromagnetic screening mesh 330 may be manufactured of a number of different materials. The screening mesh '30 serves to block the passage both in and out of radio frequency radiation and also magnetic fields. Accordingly, a suitable substance for the screening mesh 30 is conductive wire embedded within a plastic

6 3 0 carrier sheet for ease of handling.

Figure 3 illustrates a joint between two panels. Since the aluminiurn alloy sheet material from which the outer wall 6 and the inner wall 4 are manufactured is relatively soft, then a normal nut and bolt fixing would be susceptible to the holes being enlarged by applied force and the bolt being pulled through to break the joint. In order to protect against this and reinforce the joint, backing plates 34 are provided within each panel behind the point at which the fixing (in this case a bolt 36 and a nut 38) are provided. These backing plates 34 may be made of steel (preferably nitrotech treated for increased strength) which will be resistant to having the holes within it enlarged.

Figure 4 schematically illustrates the operation of the side doors 24 and the lid 20 of Figure I. In order to open the enclosure, the lid 20 is first rotated about its horizontal lid axis that runs along the top rear edge of the enclosure of Figure 2. This raises the lid groove 40 clear of the top edge of the side door 24. At this point, the side door 24 may be moved upwardly either manually or partially/totally assisted by the coil spring 27 (shown in Figure 1). Once the side door 24 is clear of the housing groove 26 in the bottom of the housing, then it may be swung about its hinged vertical access to provide access to the interior of the enclosure 2.

Weather seals 42 are provided within the lid groove 40 and housing groove 26 and are dimensioned such that when the side door 24 is held within these grooves, then the weather seals 42 are firmly pressed against the side door 24. Radio frequency interference seal 44 are also provided within the lid groove 40 and the housing groove 26 and serve to screen RFI from entering or exiting the enclosure 2. The positioning of these seals within the grooves makes the enclosure more resistant to slight warping of the side doors since the grooves Will nevertheless positively locate over the top and bottom of the side door 24 and force the seals into good contact with the door.

Figure 5 illustrates the self-locking lock mechanisms mentioned in relation to Figure 1. The castings 8 each include a lock cylinder 46. This lock cylinder 46 may be operated with a high security key and when opened pull or push upon a sleeved cable 48. The sleeved cable 48 is coupled to a self-locking lock mechanism, such as those found on car luggage compartments. These locking mechanisms lock themselves when the lid 20 is pushed closed and are sprung to release the lid 20 so that it may 7 be hinged upwards if the correct key is used within the lock cylinder 46. When the key has been used to release the lid 20 and this has been hinged back, then the side doors 24 can move upwardly sufficient to clear the housing groove 26 and then be swung open.

A hinge lip 50 is provided in each of the end panels and when the side doors 24 are shut, the outer face of each side door 24 presses against its respective hinge lip 50. The side door 24 extends behind the hinge axis and so as the main face of the side door 24 ils moved back to close the enclosure, the back edge moves forward and into abutment with the inner face of the hinged lip 50. An effective weather and RE seal may thus be provided between the hinged lip 50 and the side door 24.

8

Claims

1 An electrical apparatus enclosure comprising: an enclosure housing: a side door mounted in a side opening in said enclosure housing and hinged about a side door axis; and a lid mounted on said enclosure housing and hinged about a lid axis, a distal edge of said lid from said lid axis abutting a top edge of said side door when said side door and said lid are both shut, wherein said enclosure housing has a housing groove facing a bottom edge of said side door and said lid has a lid groove facing said top edge of said side door, such that when said side door and said lid are both shut said bottom edge of said side door is held within said housing groove and said top edge of said side door is held within said lid groove, and when said lid is open releasing said top edge of said side door from said lid groove, said side door may be moved upwards parallel to said side door axis to release said bottom edge of said side door from said housing groove thereby freeing said side door to pivot open about said side door axis.

An electrical apparatus enclosure as claimed in claim 1, wherein, when said side door is shut a hinged edge of said side door abuts and lies behind a hinge lip in said housing.

I An electrical apparatus enclosure as claimed in any one of claims 1 and 2, comprising a resilient means disposed between said housing and said side door for urging said side door upwards along said side door axis when said lid is open.

0 4. An electrical apparatus enclosure as claimed in claim 3), wherein said side door is hinged about a rod running between said housing and said side door and said C resilient means comprises a coil spring disposed around said rod between said housing and said door.

5. An electrical apparatus enclosure as claimed in any one of the preceding 9 claims, wherein said housing groove and said lid groove contain weather and radio frequency interference seals that are pushed into contact with said side door when said side door and said lid are shut.

6. An electrical apparatus enclosure as claimed in any one of the preceding claims, comprising two of said side doors within said side opening and hinged about opposite edges of said side opening, said two side doors having distal edges from said side door axes that abut when said two side doors are closed, said distal edges of said two side doors have complementary formations that engage each other when said two side doors are closed.

7. An electrical apparatus enclosure as claimed in any one of the preceding claims, comprising a self-locking lock mechanism between said lid and said housing such that said lid is locked closed when it is pushed shut.

8. An electrical apparatus enclosure as claimed in any one of the preceding claims, wherein said lid and said housing each include an end casting at each end of said lid axis.

9. An electrical apparatus enclosure as claimed in claims 7 and 8, wherein said self-locking lock mechanism includes a catch extending between said lid and said housing at each end of said lid.

10. An electrical apparatus enclosure as claimed in claims 7 and 8, wherein said self-locking lock mechanism includes a lock cylinder for receiving a key, said lock cylinder being disposed in one of end castings.

An electrical apparatus enclosure as claimed in claim 10, wherein said lock cylinder is connected to other parts of said self-locking lock mechanism via a sheathed cable.

12.

An electrical apparatus enclosure substantially as hereinbefore described with reference to the accompanying drawings.