GB2329412A - Security grille for protecting property - Google Patents

Abstract

A security grille for protecting property comprises an array of parallel rigid rods (10) of non-circular cross-section connected together by a plurality of mutually spaced links (12) to form a foldable curtain. Each end of each link (12) is formed as a collar with a rod-receiving aperture for receiving an adjacent two of the rods (10) and holding them apart in a mutually spaced relationship. One of the rod-receiving apertures, of the collar is shaped to complement the non-circular rod cross-section and prevent relative rotation between the link (12) and the rod (10) passing through that aperture, and the other rod-receiving aperture is circular in cross-section to encircle the rod (10) passing there through and permit relative rotation between the link (12) and the rod (10) passing through that aperture. Guide means are provided at the opposite ends of some only of the rods so that the curtain can be folded in a concertina fashion against one boundary of an access opening into the property or drawn across that opening and fastened in place to secure the property.

Description

TITLE Security grille for protecting property.

DESCRIPTION Field of the invention The invention relates to a security grille for protecting property. Such grilles when positioned across an access opening into a property act to prevent or deter the burglar from entering such property.

Background of the invention It is well known that burglars take advantage of unsecured doors and windows to gain access to buildings. There is currently a wide variety of equipment available on the market to help improve security in these areas. Broadly speaking such items of equipment fall into one of two categories; those that deter the burglar or those that prevent intrusion.

An example from the first category is the burglar alarm system. These systems generally employ sensors in those areas of a property that are most vulnerable to intrusion.

Hence, such a system may incorporate a passive infra-red movement sensor mounted in every room, magnetic contact detectors attached to doors and windows and an external siren mounted in a prominent position. These types of systems have been developed so as to minimize the perceived invasive characteristics of such systems; as no physical bars are used to obstruct openings, people within alarmed buildings do not feel caged in. However, burglar alarm systems of the type described above only serve to deter and will not necessarily prevent a determined intruder from entering a property.

The second category consists of systems which attempt physically to bar the would-be intruder from access to the building.

A commonly used apparatus to prevent intrusion is the roller shutter. An illustration of this type of system is shown in Figure 1.

The shutter is composed of individual sections. Each section comprises a cylindrical portion at one end, a cupped portion at the other end and a flat intermediate portion.

The uppermost section is mounted on a roller which is generally installed in casing above the opening to be protected.

The method for linking the sections together is quite simple; the cylindrical portion of one section is slotted horizontally into the cupped portion of a similar section.

Once a sufficient number of sections have been engaged in this manner, so as to cover the entire area of the opening, guide rails are secured to both vertical sides of the opening hence preventing the sections from becoming disengaged.

The shutter can then be retracted and housed in the roller casing when not in use. When required, the shutter can be extended, either manually or remotely using a motor to drive the roller. Once fully extended the bottom section is locked into position and the building is secure.

Each individual section used in these roller shutter systems is normally manufactured in one piece. This enables a high level of rigidity to be maintained between the cupped and cylindrical portions of each section. This is advantageous to the operation of the system as it helps to prevent the fouling of the retraction mechanism and keeps the sections in alignment when the shutter is opened.

It is also advantageous to keep the height of the individual sections to a minimum as this helps to reduce the diameter of the wound roll of the shutter when it is retracted.

For the reasons explained above the amount of material which can be removed, in order to give the shutter a more open characteristic, is limited; to maintain high rigidity, areas can only be removed from the flat intermediate portion of each section, and to reduce retracted roller size this intermediate portion is kept to a minimum height.

A further disadvantage of these systems is that because the roller casing is quite large and overhangs the opening, and because the closed shutters so profoundly and deleteriously affect the physical external appearance of a building, installation of these shutters requires planning permission.

Another disadvantage is that the linked sections can be prised apart by lever action.

Generally, these shutter systems are for use with unoccupied buildings. They are most frequently used on shop-fronts where the roller casing can be incorporated into the shop-front sign and openness of the system is unimportant since nobody will be in the shop when the shutter is extended.

Another form of security roller shutter that is commonly used on the inside of shop windows is a curtain grille formed from an array of horizontal bars and spacers guided by steel cables. The curtain can be lowered across the inside of the window glass and anchored at the base, or raised up out of sight on a roll. The benefits of such a system are that it permits a clear view of a window display even when the grille is lowered, and that it is relatively lightweight. A disadvantage is that it provides only poor security, since the cable guides can easily be severed. The curtain can only be hung vertically, with the bars horizontal.

It is an object of the invention to provide a security grille for protecting property which can be mounted inside or outside the building across a door or window opening; which can be designed to be opened either horizontally or vertically; which does not unduly obstruct the view through the door or window opening when closed; which occupies a small space when opened; and which provides a high degree of security when closed.

Summary of the invention The invention provides a security grille for protecting property, comprising an array of parallel rigid rods of non-circular cross-section connected together by a plurality of mutually spaced links to form a foldable curtain, wherein each end of each link is formed with a rod-receiving aperture for receiving an adjacent two of the rods and holding them apart in a mutually spaced relationship, one of the rod-receiving apertures being shaped to complement the non-circular rod cross-section and prevent relative rotation between the link and the rod passing through that aperture, and the other of the rod-receiving apertures being circular in cross-section to encircle the rod passing therethrough and permit relative rotation between the link and the rod passing through that aperture, and guide means are provided at the opposite ends of some only of the rods for constraining those ends to follow a linear path of movement; the assembly being such that the curtain can be folded in a concertina fashion against one boundary of an access opening into the property or drawn across that opening and fastened in place to secure the property. Two such grilles, referred to in this Specification as half-grilles, can be positioned at opposite sides of a door or window opening so as to meet and fastened together when closed.

This invention overcomes the disadvantage of the prior art because the links solidly and completely surround the rods and therefore cannot be prised open. A further advantage is that the grille of the invention although open in appearance behaves structurally like a number of hinged rigid panels, with the non-rotary couplings between the rods and one end of each link permitting all such links mounted on a given rod to be held coplanar with each other and behave like a solid panel. This structural rigidity is achieved however without the solid opaque appearance of a solid metal panel. The open appearance of a grille of the invention is such that even when closed across a door or window opening of a room it does not materially darken the room or become visually dominant, and does not prevent the occupants of the room from seeing out. The grille of the invention also uses less metal than does a roller shutter, and is therefore less expensive to manufacture.

Furthermore the invention has been developed to enable the grille to be foldably stored discretely within a standard window frame cavity behind the normal curtain folded width. If used indoors, installation of the grille will not require planning permission from the local authority.

Detailed description Figure 1 is a schematic perspective view, partly in section, of a prior art roller shutter security system; Figure 2 is a plan view from above of a grille according to the invention folded back against one upright of an opening; Figure 3 is a cross section through a rod of the grille of Figure 2; Figure 4 is a horizontal section through one interconnecting link of the grille of Figure 2; Figure 5 is a plan view from above of a locking mechanism of the grille of Figure 2; Figures 6a and 6b are vertical sections taken through top and bottom guide rails respectively of the grille of Figure 2; Figure 7 is a plan view from above of a second embodiment of a grille according to the invention, folded back in two halves against the uprights of an opening; Figure 8 is a plan view from above of the centre part only of the grille of Figure 7, in its closed condition; Figure 9 is a plan view from above of one end part only of the grille of Figure 7, in its closed condition; Figure 10 is a front elevation of the grille of Figure7 in its closed condition; and Figure 11 is a vertical section similar to those of Figures 6a and 6b through the top and bottom guide rails respectively of the grille of Figures 7 to 10.

Figure 1 illustrates certain deficiencies of a prior art roller shutter system, which are avoided according to the invention. The roller shutter comprises series of identical panels 1 which are made from extruded aluminium.

Each panel is formed at one end with an integral moulded rod portion 2 and at the other end with an integral moulded cup portion 3. Each cup portion of one panel can be sleeved around the rod portion of an adjacent panel to form a continuous curtain, as schematically illustrated in Figure 1. The curtain can be raised vertically by winding it around a roller (not shown) in the direction of arrow A; or it can be lowered across an access opening to a property, such as a door or window, to provide a reasonable level of security.

No matter how carefully the panels 1 are extruded, there is always a small crack between each pair of panels as indicated to an exaggerated degree as 4 in Figure 1 on the outside of a lowered shutter. A determined intruder can place a blade, for example of a robust knife, screwdriver or jemmy, into that crack and then lever apart any joint between two adjacent panels. That can be achieved by simple deformation of the aluminium without having to sever or break any metal, because the cup portions 3 do not and cannot completely encircle the rod portions 2.

Once one pivotal connection has been parted, access is easy because the roller shutter panels 1 above the parted connection can simply be rolled up to clear the access opening to the property.

When lowered, the roller shutter of Figure 1 is a solid opaque barrier, allowing no light to pass to the interior of the property. Roller shutters tend therefore to be deployed only when a property is unoccupied. This has two disadvantages. The opaque roller shutter, generally deployed on the outside of a building, is clearly visible which signals to would-be intruders that the property is unoccupied. Also the clear visibility has quite a substantial impact and may be thought objectionable by neighbours or by local planning authorities.

If window openings were to be cut into the metal of the individual shutter panels 1 of Figure 1, it would be possible to allow some daylight into the interior of the property even when the shutter was lowered. However the amount of light permitted to enter would be relatively small as the windows could not be cut so large as to weaken the anchorage of the rod portions 2 or the cup portions 3 to the remainder of their panels 1. The roller shutter would therefore still significantly darken a room when closed, and the visual impact of a lowered shutter from either inside the room or outside the building would be very significant. Also, the cutting away of portions of metal from an extruded profile is an extremely uneconomical method of manufacturing an apertured barrier.

Figures 2 to 6 illustrate a grille according to a first embodiment of the invention. The grille is formed from a number of parallel rods 10 connected together by links 12.

Figure 2 shows the grille in its folded condition at one side of an access opening, such as a door or window opening, into a building. A first rod 10a is secured alongside one side of the opening and is connected to a second rod 10b by a vertical array of spaced links 12a.

The second rod 10b is connected to a third rod 10c by a similar vertical array of spaced links 12b, and so on until a final rod 101 which is connected to a previous rod 10k by an array of shorter but otherwise similar links 12k.

Each rod 10 is of a constant four-lobed section as shown to an enlarged scale in Figure 3. Each link 12 is identical to the others with the exception of its overall length (compare links 12a and 12k) and is as shown to a slightly less enlarged scale in Figure 4. Each link 12 comprises a lobed collar portion 14 at one end and a cylindrical collar portion 16 at the other end. The internal sectional profile of the lobed collar portion 14 complements the external sectional profile of the rods 10 so that when a lobed collar portion 14 of a link 12 is sleeved over a rod 10 there is no relative rotation permitted between the rod and the link. When a number of links 12 are sleeved over the same rod 10 each one using the lobed collar portion 14 in the same angular orientation, the links are held together in the same angular orientation, each one relative to the others.

Figure 4 also shows a side bore 18 formed in each lobed collar portion 14, for receiving a helical pin (not shown) which is driven through the bore 18 and an outer lobe of the rod 10 on which the collar portion is sleeved, to secure the links against axial movement on the rod 10.

Instead of a side bore 18 opening to one side only of the lobed collar portion 14 as shown, the side bore may pass completely through the lobed collar portion 14 to permit removal of the helical pin if that should be thought to be desirable in practice. Alternatively instead of the side bore 18 as shown and helical pin, the axial constraint on the links sleeved onto a rod may be provided by grub screws or any other fixing method.

The cylindrical collar portion 16 of each link 12 is of a diameter such that it makes only line contact with the outermost extremities of the four lobes of the rod 10 (see Figure 2, rods 10a, 10c, 10e, ...). That creates a smooth low-friction pivotal movement between the cylindrical collar portions 16 and the rods 10 on which they are sleeved.

The complete grille of Figure 2 is made up of a first rod 10a onto which is sleeved7 using their cylindrical collar portions 16, a first array 12a of links 12. The lobed collar portions 14 of the links in the first array 12a are sleeved around and axially secured to a second rod 10b, alternating with cylindrical collar portions 16 of the links 12 of a second array 12b. The lobed collar portions 14 of the links 12 in the second array 12b are sleeved around and axially secured to a third rod 10c, alternating with a third array 12c of links linking that rod in a similar manner to a fourth rod 10d, and so on until a final rod 101.

The final rod 101 also carries a pair of locking links 18 or 19 as shown in Figure 5. The links 18 as illustrated in Figure 4, for example, could cooperate with locking links 19 on an opposite door or window frame or on a similar grille fastened to the opposite door or window frame, to permit the grille or a pair of half grilles to be fastened across the door or window opening by means of a conventional lock mechanism 20 (Figure 5).

Top and bottom guides are provided as illustrated in Figures 6a and 6b. The top guide (Figure 6a) comprises an extruded channel member 22 which has two flanges 24 for securing to the top of the door or window frame and a central channel 26 for receiving a hard nylon moulded slide member 28 which is screwed to the top of an associated rod 10. Alternate rods 10a, 10c, 10e, 10g, 10i and 10k of Figure 4 are guided in the channel 26, the intermediate rods 10b, 10d, 10f, 10h, 10j and 101 being free. The bottom guide (Figure 6b) is similar except that its channel 30 is shallower and receives hard nylon slide members 32 screwed to the bottoms of the same guided rods.

Vertical movement between the top slide members 28 and the guide channel 26 is permitted at the top of the grille but no corresponding movement is permitted between the bottom slide members 32 and the guide channel 30 at the bottom of the grille. This ensures smooth sliding while any misalignment of the top and bottom channel members, due to the top and bottom members of the door or window frame being not quite level, is accommodated in the top guide.

Typically the links 12 of Figure 2 could be at most about 120 mm long and adjacent links on each rod 10 could be spaced apart by at most about 250 mm. That would provide a light and airy appearance to the grille while still maintaining excellent security.

The rods 10 and links 12 are preferably extruded from high specification aluminium alloy with a tensile strength of at least 200 Newtons per square centimetre and a high elongation at break. The links 12 may be first extruded as a continuous panel with the section shown in Figure 3 and then sliced into individual links each 15 to 25 mm wide. The rods 10 may be solid, or may be extruded with a hollow central core 11 as shown in Figure 3. The hollow core may be circular in section or lobed as illustrated.

A lobed core 11 makes it easier to secure the top and bottom slide members 28 and 32 using self-tapping screws which can more easily cut into a lobed core than into a circular core.

A valuable additional security feature, if the rods are hollow as described above, is the inclusion of a high tensile steel wire down the centre of each hollow core 11.

If the steel wire is able to turn freely within the hollow core 11 of the rod 10, then that makes it very difficult indeed to cut through the rods with a hacksaw.

A second embodiment of the invention is illustrated in Figures 7 to 11 which should be read in conjunction with the description of Figures 2 to 6. The significance of Figure 7 is that the links 12 are not all the same length.

Three different lengths of link are used. Links 12' have a length 1'; links 12'' have a length l''; and links 12"' have a length 1'''. The length relationship is 1' 1'' > 2FF?; and the sequence of links along the grille is 12''', 12'' 12', 12', 12 F F F 12 , 12', 12'', The above sequence enables the links to become nested together as shown in Figure 7 when folded back against the door or window frame, occupying less folded width than the corresponding number of equal length links in Figure 2.

It will be appreciated that top and bottom guides for the guided rods 10 of the grille of Figure 7 to 11 will each have two guide channels (see Figure 11), one (26X,30X) for the rods 10a, 10e, ... and the other (26Y, 30Y) for the rods 10c, 10g, ... The first pair of top 26X and bottom 30X guide channels will guide the rods 10a, 10e, ... along the line X in Figures 7 to 9 and the second pair of top 26Y and bottom 30Y guide channels will guide the rods 10c, 10g, ... along the line Y. The reference numbers used in Figures 7 to 11 are otherwise the same as those used in Figures 1--to 6.

Any odd number n of different length links may be used in the above sequence, together with m guide channels where 2m = n + 1.

The grilles of Figures 2 to 11 have been described as being horizontally sliding, and it is true that a horizontally slidable grille is an important aspect of the invention since prior art roller shutters and curtain grilles have generally been vertically movable only.

There is therefore a great need for a secure and reliable grille that opens horizontally. However the grille of the invention is not limited to horizontal movement, and can easily be mounted for vertical opening. Preferably a vertically opening grille would include, in addition to all of the features described above with reference to Figures 2 to 11, a torsion spring (not illustrated) incorporated into each link collar 16 to urge the grille into its folded stowed condition by an amount preferably just sufficient to counterbalance the weight of the grille.

Claims (11)

1. A security grille for protecting property, comprising: an array of parallel rigid rods of non-circular cross-section connected together by a plurality of mutually spaced links to form a foldable curtain, wherein each end of each link is formed as a collar with a rod-receiving aperture for receiving an adjacent two of the rods and holding them apart in a mutually spaced relationship, one of the rod-receiving apertures being shaped to complement the non-circular rod cross-section and prevent relative rotation between the link and the rod passing through that aperture, and the other of the rod-receiving apertures being circular in cross-section to encircle the rod passing therethrough and permit relative rotation between the link and the rod passing through that aperture, and guide means are provided at the opposite ends of some only of the rods for constraining those ends to follow a linear path of movement; the assembly being such that the curtain can be folded in a concertina fashion against one boundary of an access opening into the property or drawn across that opening and fastened in place to secure the property.

2. A security grille according to claim 1 wherein each rod passes alternately through the non-circular apertures through the collars of one or more links and the circular apertures through the collars of the next one or more links.

3. A security grille according to claim 1 or claim 2, wherein the links are prevented from movement axially of the rods by anchor means associated with the collars having non-circular apertures.

4. A security grille according to claim 3, wherein each anchor means comprises a bore passing chordally through one wall of the collar having a non-circular aperture from the outside to the aperture, and a helical pin passing through the bore and into engagement with the rod passing through the aperture.

5. A security grille according to claim 3, wherein the anchor means comprises a bore passing chordally through the collar having a non-circular aperture from one outside wall to the other and cutting chordally across the aperture, and a helical pin passing through the bore and into engagement with the rod passing through the aperture.

6. A security grille according to claim 3, wherein the anchor means comprises a grub screw passing through a wall of the collar having a non-circular aperture and into engagement with the rod passing through the aperture.

7. A security grille according to any preceding claim, wherein all of the links are the same length.

8. A security grille according to any of claims 1 to 6, wherein the links are of different lengths to permit more compact folding of the grille into its stowed condition.

9. A security grille according to any preceding claim, wherein each rod is hollow and includes down its hollow centre a high tensile steel wire that is freely rotatably within the rod.

10. A security grille substantially as described herein with reference to Figures 2 to

11.