GB2306990A

GB2306990A - Security grille with movable bars

Info

Publication number: GB2306990A
Application number: GB9522211A
Authority: GB
Inventors: Martyn Henry Robinson
Original assignee: COMPOUND SECTIONS Ltd
Current assignee: COMPOUND SECTIONS Ltd
Priority date: 1995-10-31
Filing date: 1995-10-31
Publication date: 1997-05-14
Also published as: GB9522211D0

Abstract

A security grill comprises a pair of sunstantially parallel elongate guide members 1,2 and a plurality of bars 4a-4f, the ends of the bars being received in, and adapted for sliding movement relative to, the guide members. The bars 4a-4f may thus be moved towards and away from one another to open and close the grill. The grill includes a locking mechanism (6, figures 3 and 4) which, when locked, engages the ends of the bars to prevent the grill being opened.

Description

SECURITY GRILL The present invention relates to a security grill and in particular, although not exclusively, to a security grill for an opening, such as a window or a door, in a building.

Security grills are used to prevent people from breaking into homes and commercial premises through windows and doors. In the case of doors and also windows that may be used as an emergency fire escape it is obviously essential that the grill must be readily removable or openable. In fact, the fire regulations of some countries require that such grills should be removed or opened whenever the premises are occupied. For convenience of use, it is preferable that the grill should be openable. It is also desirable that the grill, at least when opened, does not spoil the appearance of the building or reduce significantly the amount of natural light entering through the windows. It goes almost without saying that the grill must also be completely secure when locked.

Many types of grill have been proposed that meet some of these requirements to a greater or lesser extent. However, none has been proposed that meets all the requirements and is simple to operate, readily adaptable to windows and doors of different sizes and relatively inexpensive to manufacture and fit.

It is an object of the present invention to provide a security grill that mitigates at least some of the problems of existing grills.

According to the present invention there is provided a security grill comprising a pair of elongate guide members, said guide members being arranged substantially parallel to one another, a plurality of bars, the ends of said bars being attached to the guide members and adapted for sliding movement relative thereto whereby the bars may be moved towards and away from one another to open and close the grill, a linking mechanism connecting each bar to an adjacent bar and arranged to limit the relative separation of the pair of linked bars, and a locking mechanism associated with the guide members and arranged, when locked, to engage the ends of the bars in their spaced apart positions, so preventing the grill from being opened.

The locking mechanism, being associated with the guide members, is compact and secure. The linking mechanism ensures that when the grill is closed, the bars are spaced substantially evenly from one another. The mechanism is designed to ensure that the bars are positioned very precisely when the grill is closed, which enables the locking mechanism to engage the ends of the bars correctly, so making the grill easy to operate. The grill is readily adaptable to windows and doors of different shapes and sizes and is relatively inexpensive to manufacture and fit.

Advantageously, each guide member includes an elongate channel formation in which the ends of the bars are received and the locking mechanism comprises an elongate locking member received within the channel formation of each guide member and rotatable about the longitudinal axis thereof, the elongate-locking member including a plurality of stop surfaces that, in the locked position, extend transversely across the channel formation to prevent movement of the bars therein.

This locking arrangement locks each bar in position within the guide members and is therefore more secure than arrangements in which only one bar is locked in position.

The elongate locking member preferably comprises a slotted tube having a longitudinal slot and a plurality of transverse slots extending substantially circumferentially therefrom, the side edges of the transverse slots comprising said stop surfaces. In this form, the locking mechanism is particularly simple and inexpensive to manufacture, whilst being compact and secure.

The security grill may include means for rotating the elongate locking members about the longitudinal axes of the channel formations. for example, short levers may be provided for rotating the locking members.

The grill may include lock means, engageable with the elongate locking members, to prevent rotation thereof.

This prevents the grill being opened by unauthorised persons.

The linking mechanism advantageously comprises a sliding link member fixedly secured to an end of one of each pair of linked bars and slidingly connected to an end of the other one of said pair of linked bars. This mechanism is mechanically simple, but provides very precise control of the separation of the bars, which is important for correct engagement by the locking mechanism.

The sliding link members of successive pairs of linked bars may overlap one another, and may be stepped outwards from one another. These features allow the link members to slide past one another as the grill is opened without fouling. Smooth and reliable operation of the grill is thereby ensured.

The sliding link mechanism may include means for adjusting the displacement of the sliding link member from the ends of the bars. This allows the sliding link members to be stepped successively outwards from the ends of the bars.

The bars may all therefore be cut to the same length. This greatly simplifies manufacture and fitting of the grill and so reduces cost. It also makes the grill suitable for do it-yourself assembly and fitting by unskilled persons.

Advantageously, the grill is arranged such that, in use, the guide members are substantially vertical and the bars are substantially horizontal, the grill further including means for raising the bars. The weight of the bars is thus carried by the means for raising the bars rather than the guide members and this helps to ensure smooth and reliable operation of the grill. The means for raising the bars may be manually operated or motor driven.

Advantageously, the means for raising the bars comprises a flexible member having a first end secured to a rotatable member mounted in the upper part of the grill and a free end secured to the lowest bar, and means for rotating the rotatable member to wind the flexible member in or out.

Winding the flexible member in thus lifts the lowest bar, which in turn lifts the other bars.

The free end of the flexible member preferably passes through guide means associated with the ends of all but the lowest of the sliding bars. This helps to guide the flexible member and contributes to reliable operation of the grill.

The flexible member preferably comprises a torsion spring.

The spring is able to carry part of the weight of the bars, which reduces the effort needed to raise the bars.

The rotatable member preferably comprises a bar, rotatably mounted in the upper part of the grill. By rotating the upper bar, the flexible member can be wound in or out to raise or lower the bars.

An embodiment of the invention will now be described with reference to the accompanying drawings, of which: Fig. 1 is a front view of the security grill with the bars closed; Fig. 2 is a front view of the grill with the bars open; Fig. 3 is a cross-sectional view of one of the guide members taken on line III-III of Fig. 1, showing the locking mechanism in an unlocked state; Fig. 4 is a cross-sectional view of one of the guide members taken on line IV-IV of Fig. 1, showing the locking mechanism in a locked state; Fig. 5 is a front view of one of the locking members; Fig. 6 is an exploded perspective view of the mechanism for linking the ends of the bars; Fig. 7 is side view of one of the linking members; Fig. 8 is a side view of a cup washer; Fig. 9 is a front view of a cup washer; Fig. 10 is a front view of an inner member of an end plug assembly; ; Fig. 11 is a top view of an inner member of an end plug assembly; Fig. 12 is a side view of an inner member of an end plug assembly; Fig. 13 is a front view of an outer member of an end plug assembly; Fig. 14 is a side view of an outer member of an end plug assembly, and Fig. 15 is a cross-sectional view of a guide member taken on line XV-XV of Fig. 1, showing the mechanism for raising and lowering the bars.

As shown in Figs. 1 to 4, the security grill comprises a pair of upright guide members 1,2, each of which consists of a channel section, for example of rolled steel or extruded aluminium, of substantially square cross-section.

A longitudinal slot 3 extends along the length of each guide member on one side thereof. The two guide members 1,2 are arranged substantially vertically with the longitudinal slots facing one another.

A plurality of tubular steel bars 4a-4f extend horizontally between the two guide members, the ends of the bars being received in the longitudinal slots 3. The bars 4a-4f are able to slide up and down within the slots 3. The top bar 5 is fixed and is mounted within the guide members 1,2 for rotation about its longitudinal axis, as will be described in more detail below.

Within each guide member 1,2 there is provided a locking member 6 in the form of a tube of circular cross-section.

The locking member 6, which is shown in more detail in Fig.

5, has a longitudinal slot 7 that extends the length of the tube and a plurality of short slots or notches 8 that extend transversely from the longitudinal slot 7 at spaced locations along its length. The locking member 6 is arranged to be rotatable within the guide member 1,2 about its longitudinal axis.

When the locking member 6 is located in the position shown in Fig. 3, with its longitudinal slot 7 aligned with the slot 3 of the guide member 1,2, the bars 4a-4f are able to slide freely up and down within the guide members 1,2.

When the locking member 6 is rotated about its axis through an angle of approximately 90 to the position shown in Fig.

4, its longitudinal slot 7 is no longer aligned with the slot 3 of the guide member 1,2 and the ends of the horizontal bars 41-4f are received in respective ones of the transverse slots 8. This locks the bars 4a-4f in position and prevents them being raised.

The height of the locking members 6 is such that when the bars 4a-4f have been raised, as shown in Fig. 2, the upper ends 9 of the locking members 6 are approximately level with the bottom edge of the lowest bar 4f. Thus, when the locking members 6 are rotated to the locked position shown in Fig. 4, the bars rest on, and are supported by, the locking members 6. The upper end 9 of the locking member 6 is preferably cut in the form of a helix, to act as a cam surface so ensuring smooth engagement with the lower surface of the lowest bar 4f.

The locking members 6 are rotated by means of short levers 10 that pass through horizontal slots 11 in the lower parts of the guide members 1,2. Deadlocks 12 are provided towards the lower ends of the guide members 1,2, which engage the locking members 6 when locked to prevent them being rotated. Thus, the grill may be locked to prevent the bars 4a-4f being raised or lowered.

As shown in Fig. 6, the bars 4a-4f are connected to one another by a sliding link assembly. Located in the end of each bar 4a-4f is an end plug assembly 13, to each of which is attached a link plate 14a-14e. The link plates 14a-14e, one of which is shown in more detail in Fig. 7, are made of stainless spring steel and have a length of approximately 180mm. A slot 15 of length approximately 140mm is provided towards the lower end of each link plate 14. The link plates 14a-14e are attached at their upper ends to the end plug assemblies 13 by means of rivets 16.

The link plates 14a,14b of each pair of linked bars 4a,4b overlap one another, the upper link plate 14a lying on the outside of the lower link plate 14b. The upper link plate 14a is connected to the lower link plate 14b by a sliding mechanism comprising a pair of brass washers 17,18 arranged on either side of the upper link plate 14a and joined to the lower plate by a rivet 19. As shown in Figs. 8 and 9, the outer washer 18 has a cup 20 formed on its inner face, which passes through the slot 15 in the upper link plate 14a. The height of the cup 20 is slightly greater than the thickness of the link plate 14a and this allows the washers 17,18 to slide along the slot 15 of the link plate 14a.

The linked bars 4a,4b are thus able to slide towards or away from one another to the separation determined by the length of the link plate 14a. The lower ends 21 of the link plates 14a-14e are bent outwards, to prevent fouling.

The lower bars 4b-4f are linked together in a similar fashion and the uppermost sliding bar 14a is likewise linked to the rotatable bar 5.

The end plug assembly 13 comprises an inner member 22 of zinc plated cast steel, and a pair of outer members 23 of hard moulded plastics, for example nylon. The inner member 22, which is shown in more detail in Figs. 10 to 12, comprises a pair of vertical side walls 24 that are joined to one another by inner and outer vertical end walls 25a,b.

The dimensions of the side walls 24 and the inner end wall 25a are such as to allow the inner member 22 to be inserted into an end of one of the horizontal bars 4a-4f. The upper and lower edges of the side walls 24 are provided with serrations 26, having a pitch of lmm. The inner ends of the side walls 24 and the inner end wall 25a have a height corresponding to the bottoms of the serrations 26. The outer end wall 25b extends vertically above and below the side walls 24 and is provided with a pair of counter sunk holes 27 to receive the rivets 16 that connect the link plates 14a-14e to the end plug assemblies 13.

One of the outer members 23 of the end plug assembly 13 is shown in detail in Figs. 13 and 14. The outer member 23 includes an elongate body 28 having a lower portion 28a of substantially rectangular cross-section and an upper portion 28b having a cross-section comprising a segment of a circle. The curved surface of the upper portion 28b is matched to the internal radius of the horizontal bars 4a-4f and the width of the lower portion 28a is selected to be a push fit in the slot between the side walls 24 of the inner member 22. The upper portion 28b thus has exposed lower surfaces 29 that overhang the lower portion 28a and these surfaces are provided with serrations 30 matching those of the inner member 22. An end wall 31 having a curved upper surface 32 matched to the external diameter of one of the horizontal bars 4a-4f is provided at the outer end of the outer member 23.

To assemble the end plug assembly 13, one of the outer members 23 is placed on top of the inner member 22 and is pressed downwards so that the lower portion 28a is forced between the side walls 24 of the inner member 22 and the serrations 26,30 of the inner and outer members are brought into mutual engagement. A second outer member 23 is similarly brought into engagement with the serrations on the lower edges of the inner member 22. The end plug assembly 13 is then pushed into an end of one of the horizontal bars 4a-4f, until the end walls 31 of the outer members 23 abut the end of the bar.

The inner member 22 projects outwards beyond the end of the bar 4a-4f by a distance determined by the relative engagement of the serrations 26,30 on the inner and outer members 22,23. Thus, by adjusting the relative positions at which the serrations engage one another, it is possible to adjust in steps of lmm the distance by which the inner member 22 projects beyond the end of the bar 4a-4f.

In the assembled window grill, each end plug assembly 13 is arranged to project lmm further from the end of the horizontal bar 4a than the end plug assembly 13 of the bar 4b immediately below. The link plates 14a-14e are thus stepped outwards from the bottom of the grill to the top, which allows the link plates to slide past one another without fouling when the bars 4a-4f are raised.

The mechanism that allows for rotation of the top bar 5 is shown in Fig. 16. The bar 5 includes a moulded nylon end plug assembly 33, which has a push fit in the end of the bar 5. A steel pivot pin 34 is secured within the end plug 33 and is pivotably mounted in a nylon half bearing 35 that is riveted to an inner surface of the guide member 2.

The end plug assembly 33 includes at its outer end a toothed pulley 36 for a nylon ball chain 37. The ball chain 37 passes around the pulley 36 and extends through a slot 38 in the front face of the guide member 2 and hangs in a loop at the side of the security grill, as shown in Figs. 1 and 2. The top bar 5 can be rotated in either direction by pulling one or other length of the ball chain 37.

Secured to, and wrapped around each end of the top bar 5 is a spiral torsion spring 39. The outer end of each torsion spring 39 leads downwards through the slot formed by the side walls 24 of the end plug assembly inner member 22 to the lowest bar 4f, to which it is secured. The springs 39 have a tendency to adopt a tightly wound state around the top bar 5, and they thereby exert a lifting force on the lowest bar 4f.

The strength of the springs 39 is selected such that they lift the lowest bar 4f (and, thereby, the bars 4e,4d,4c that lie above it) to approximately half the height of the guide members 1,2. The springs 39 thus carry a substantial portion of the weight of the bars 4a-4f, which allows the bars to be raised to the top of the grill or lowered to the bottom with relative ease by means of the ball chain 37.

When the grill is to be closed, the locking member 6 are first rotated to the unlocked position as shown in Fig. 3, so that the slots 7 are aligned with the slots 3 of the guide members 1,2. As the lowest bar 4f is then no longer supported by the upper ends 9 of the locking members 6, the bars 4a-4f fall approximately half-way down the grill, as determined by the strength of the springs 39. The bars are lowered to the bottom of the grill by pulling on the ball chain 37, thereby rotating the top bar 5 and causing the springs 39 to unwind further.

When the bars 4a-4f have been lowered to the limit of their possible travel as determined by the number and length of the link plates 14a-14e, the locking members 6 are rotated to their locked positions, as shown in Fig. 4, by means of the levers 10. The ends of the bars 4a-4f are thus received within the transverse slots 8, which prevents the bars being raised. The correct alignment of the bars with the slots 8 is ensured by the precision of the sliding link mechanism. The locking members 6 are then secured in their locked positions by pressing in the deadlocks 12.

To raise the bars 4a-4f, the deadlocks 12 are first released and the locking members 6 are then rotated to the unlocked positions shown in Fig. 3 by means of the levers 10. The bars 4a-4f are thus released and the springs 39 lift them to approximately half the height of the grill.

The bars 4a-4f are raised to the top of the grill by wulling on the ball chain 37, and the locking members 6 are then rotated back to the locked position to retain the bars in the raised position.

If desired, the grill may include drive motors to lift the bars 4a-4f and/or to rotate the locking members 6.

Operation of the grill may thus be fully automated. The springs 39 may also be replaced by cords, wires or other flexible elements, if desired. Further, if required, the grill may be adapted for horizontal opening, with vertical bars moving in horizontal guide members. In that case, drive means may be required both for opening and for closing the bars.

Claims

1. A security grill comprising a pair of elongate guide members, said guide members being arranged substantially parallel to one another, a plurality of bars, the ends of said bars being received in the guide members and adapted for sliding movement relative thereto whereby the bars may be moved towards and away from one another to open and close the grill, a linking mechanism connecting each bar to an adjacent bar and arranged to limit the relative separation of the pair of linked bars, and a locking mechanism associated with the guide members and arranged, when locked, to engage the ends of the bars in their spaced apart positions, so preventing the grill from being opened.

2. A security grill according to claim 1, in which each guide member includes an elongate channel formation in which the ends of the bars are received and the locking mechanism comprises an elongate locking member received within the channel formation of each guide member and rotatable about the longitudinal axis thereof, the elongate locking member including a plurality of stop surfaces that, in the locked position, extend transversely across the channel formation to prevent movement of the bars therein.

3. A security grill according to claim 2, in which the elongate locking member comprises a slotted tube having a longitudinal slot and a plurality of transverse slots extending substantially circumferentially therefrom, the side edges of the transverse slots comprising said stop surfaces.

4. A security grill according to claim 2 or claim 3, including means for rotating the elongate locking members about the longitudinal axes of the channel formations.

5. A security grill according to any one of claims 2 to 4, including lock means, engageable with the elongate locking members, to prevent rotation thereof.

6. A security grill according to any one of the preceding claims, in which the linking mechanism comprises a sliding link member fixedly secured to an end of one of each pair of linked bars and slidingly connected to an end of the other one of said pair of linked bars.

7. A security grill according to claim 6, in which the sliding link members of successive pairs of linked bars overlap one another.

8. A security grill according to claim 7, in which the sliding link members of successive pairs of linked bars are stepped outwards from one another.

9. A security grill according to claim 7 or claim 8, in which the sliding link mechanism includes means for adjusting the displacement of the sliding link member from the ends of the bars.

10. A security grill according to any one of the preceding claims, the grill being arranged such that, in use, the guide members are substantially vertical and the bars are substantially horizontal, the grill further including means for raising the bars.

11. A security grill according to claim 10, in which the means for raising the bars comprises a flexible member having a first end secured to a rotatable member mounted in the upper part of the grill and a free end secured to the lowest bar, and means for rotating the rotatable member to wind the flexible member in or out.

12. A security grill according to claim 11, in which the free end of the flexible member passes through guide means associated with the ends of all but the lowest of the sliding bars.

13. A security grill according to claim 11 or claim 12, in which the flexible member comprises a torsion spring.

14. A security grill according to any one of claims 11 to 13, in which the rotatable member comprises a bar, rotatably mounted in the upper part of the grill.

15. A security grill substantially as described herein with reference to, and as illustrated by, the accompanying drawings.