A stay

Abstract: A nose portion (21) (or an end cap (9)) of a stay (1), comprising a weakened region (39) which, when subjected to a force, greater than a predetermined force, acting to open a vent (not shown) mounted on the stay (1), in use, collapses to expose a protrusion (37) which engages the end cap (9) (or the vent arm (7)) of the stay (1) to resist further opening of the vent. Such a nose portion (or end cap) can help to prevent unauthorised opening of a stay.

Description: This invention relates to stays, and in particular to friction stays. Friction stays and the like for supporting a vent between an open position and a closed position relative to a support track mounted on a fixed frame of a building are well known. Such friction stays often include a support track, a slider mounted in the support track and a vent arm, attached by means of struts and/or links to the support track and to the slider, which is movable between an open position and a closed position. In the closed position, the vent arm overlies the support track and a nose portion or end point of the vent arm is received in an end cap of the support track. The end cap and nose portion are designed to increase the pull-in of the vent arm, and hence the vent, as the vent closes. Although the aforementioned prior art friction stays are relatively secure and provide good closing of a vent mounted on the vent arm, serious intruders trying to enter a building can sometimes lever open the vents, mounted on such friction stays, using crow-bars and the like. More particularly, an intruder can sometimes exert such a high force on the friction stay that either the nose portion of the vent arm escapes upwards and out of the top of the end cap or, alternatively, if the vent arm bends, the end point may escape out of the front of the end cap. The present invention aims to improve upon the known prior art friction stays, such as disclosed in GB-A-2133074 (which discloses a stay having the features of the first part of claim 1), by providing an arrangement which enables a stay to have additional strength against unwanted opening of the stay. With the foregoing in mind, the present invention provides a stay comprising an end cap mounted on a support track and a vent arm having a nose portion shaped to be received in the end cap, the vent arm being attached to the support track via struts and/or links and being movable between an open position and a closed position with the nose portion in the end cap in the closed position, characterised by a barb or hook projection on the free end of the vent arm covered by the nose and/or on the cap and a weakened region on the nose and/or cap, such that when a predetermined force acting to open the vent arm from the closed position is exceeded the weakened region or regions collapses to expose the or each projection which penetrates the nose and/or cap covering it and engages the other of the end cap/nose portions to immobilise the stay. Preferably the weakened region incorporates at least one aperture through the nose portion. The weakened region could, however, simply be an area of lesser thickness or an area of weaker material than the remainder of the nose portion. The nose portion is preferably an asymmetric nose portion. Thus, during normal use of the nose portion, additional pull-in of the vent mounted on the stay will occur. Although the nose portion may be formed integrally with the vent arm of a friction stay or the like, more preferably the nose portion is a separate component of the stay which is adapted to be mounted on an end of the vent arm. Preferably the nose portion comprises a mounting aperture for receiving a rivet passing through the vent arm, in use, to attach the nose portion to the vent arm. The rivet may also be used to attach the vent arm to a strut or link which forms part of the remainder of the friction stay. The nose portion also preferably comprises a spigot for engaging a recess or aperture in the vent arm to assist in retaining the nose portion in a fixed position relative to the vent arm. The nose portion preferably comprises a wall defining a recess shaped to receive an end of a vent arm, the wall being attached to a body portion of the nose portion by the weakened region such that the wall collapses when the force, greater than the predetermined force, is applied, during use. The nose portion may be formed from plastics material, although any other suitable material or combination of materials could be used. The nose portion is preferably a one-piece plastics moulding. Although the projection is preferably formed integrally with the vent arm, in another embodiment the projection could be formed as part of the nose portion itself. In a preferred embodiment, the end cap includes a base, side walls and a top cover to prevent unwanted removal of the nose portion from the end cap by lifting of the nose portion out of the end cap. Such an arrangement provides additional security against an intruder attempting to force open a vent mounted on the stay. If the end cap includes a weakened region, the weakened region may incorporate at least one recess in the end cap. The weakened region could, however, simply be manufactured from a weaker material. The end cap is preferably an asymmetric end cap. An end cap in a stay according to the present invention may comprise a main cap and an insert adapted to fit into the main cap, wherein the insert is designed to collapse as a force, greater than a predetermined force, is applied. Preferably both the main cap and the insert include a mounting aperture for receiving a rivet passing through the support track to attach the complete end cap to the support track. The main cap is preferably formed from metal. Although the insert may also be formed from metal, it is preferably formed from plastics material. Specific embodiments of the present invention are now described, by way of example only, with reference to the accompanying drawings, in which:- Fig. 1 is a plan view of a friction stay, incorporating a nose portion according to the present invention, in an open position; Fig. 2 is a side view of the friction stay of Figure 1 in a closed position; and Fig. 3 is an enlarged plan view of the nose portion shown in Figures 1 and 2. With reference to the drawings, a friction stay 1 comprises a support track 3, a slider 5, a vent arm 7 and an end cap 9. The vent arm 7 is attached via a first link 11 to a fixed pivot point 13 on the support track 3. The vent arm 7 is also pivotally mounted to the slider 5 via a second link 15. A strut 17 joins the slider 5 to the first link 11 and a reinforcing link 19 joins the strut 17 to the vent arm 7. By means of these struts and links, and due to the slider 5 being able to move back and forth along the support track 3, the vent arm 7 may move between an open position (as shown in Figure 1) and a closed position (as shown in Figure 2) overlaying the support track 3. Such a friction stay configuration is well known. On the end of the vent arm 7, nearest the end cap 9, a nose portion 21, embodying a first aspect of the present invention, is mounted. More particularly, the nose portion 21 includes a mounting aperture 23, which receives a rivet 25 joining the vent arm 7 to the second link 15. The nose portion 21 is held by the rivet 25 between the vent arm and the second link 15. The nose portion 21 also includes a spigot 27, which engages in an aperture 29 in the vent arm 7, to prevent rotation of the nose portion 21 relative to the vent arm 7. The nose portion 21 is asymmetric and shaped to be received in the end cap 9, which is correspondingly asymmetric. The nose portion 21 includes a generally planar body portion 31, from which the spigot 27 protrudes, and an upstanding wall portion 33, which shields the end edge of the vent arm 7. More particularly, the wall portion 33 defines a recess 35 (about 2 mm in depth), which is shaped to receive the end of the vent arm 7, so that the body portion 31 of the nose portion 21 lies flat against one side surface of the vent arm 7 and the top of the wall portion 33 of the nose portion 21 lies substantially flush with the other side surface of the vent arm 7. The end of the vent arm 7, within the recess 35 of the nose portion 21, is shaped in a similar asymmetric fashion to the nose portion 21, but the end edge of the vent arm 7 also includes a barb or hook 37. This barb or hook 37 is hidden behind the wall portion 33 of the nose portion 21 during normal use of the friction stay 1. The wall portion 33, however, includes a weakened region defined by two windows or apertures 39, which pass through the nose portion 21. This weakened region is sufficiently strong to withstand normal operation of the friction stay 1, but if forced entry is attempted by an intruder, the weakened region of the wall portion 33 collapses, thereby exposing the hook 37. As the intruder tries to force open the friction stay 1, the hook 37 digs into and grips an inside surface 40 of the end cap 9 to resist further opening of the friction stay 1. In order that the wall portion 33 of the nose portion 21 is sufficiently strong to satisfy normal usage, but is sufficiently weak in the weakened region to collapse when an appropriate force is applied, the nose portion is manufactured from plastics material. Due to the simplicity of the nose portion 21, it can be made as a one-piece moulding. In the embodiment of the invention shown in Figures 1 to 3 of the drawings, the end cap 9, which may be formed from a plastics material, a metal or some other appropriate material, includes a base region 41 which extends into the support track 3 and is held therein by means of a rivet 43 acting between the two. The end cap 9 also includes side walls 45 and a top cover 47 joining the upper edges of the side walls 45. By incorporating the top cover 47, the end of the vent arm 7 supporting the nose portion 21 cannot be lifted by an intruder up and out of the end cap 9, but the intruder must force the nose portion 21 out of the front of the end cap 9. When such action is attempted, the weakened region of the nose portion 21 collapses and the hook 37 of the vent arm 7 engages and grips the inside surface 40 of the end cap 9 to resist further unauthorised opening of the friction stay 1. In an alternative embodiment of the present invention, which is not shown in the accompanying drawings, the protrusion (which is to be exposed when forced entry by an intruder is attempted) is formed as part of the end cap on the support track, rather than the nose portion of the vent arm. Indeed, the arrangement shown in Figures 1-3 of the accompanying drawings can be reversed, such that the end cap incorporates a weakened region, which can collapse to expose a protrusion, such as a barb or hook, formed on the inside of the end cap. If such an end cap is used, the nose portion of the vent arm can be a standard nose portion, which does not incorporate a weakened region or a protrusion mounted thereon. (Of course, in theory, both the end cap and the nose portion could both include weakened regions and protrusions which interlock when a force, above a predetermined force, is exerted on the stay.) If the end cap, rather than the nose portion, is to include the protrusion and weakened region, the end cap can either be formed as a metal casting having a recess defining a weakened region or, alternatively, a plastics insert could be introduced into a metal main cap to define a complete end cap according to the present invention. If a one-piece end cap is used, this can be readily attached to a support track as in the normal way. When a force above a predetermined force is applied, during illegal opening of the vent, the weakened region collapses and exposes a protrusion which digs into and grips an edge of the nose portion of the vent arm to prevent further unwanted opening of the stay. Alternatively, if a two-piece end cap is used, the insert and main cap both include a mounting aperture for receiving a rivet, which passes through the support track, to attach the three components together. When this embodiment is used, it is the plastics insert which collapses to expose a protrusion on the main cap, which then bites into the nose portion of the vent arm to resist further opening of the vent mounted on the vent arm. It will of course by understood that the present invention is described above purely by way of example, and that modifications of detail can be made within the scope of the invention.

Claims: A stay (1) comprising an end cap (9) mounted on a support track (3) and a vent arm (7) having a nose portion (21) shaped to be received in the end cap (9), the vent arm (7) being attached to the support track (3) via struts and/or links (11,15,17,19) and being movable between an open position and a closed position with the nose portion in the end cap in the closed position, characterised by a barb or hook projection (37) on the free end of the vent arm (7) covered by the nose (21) and/or on the cap (9) and a weakened region (39) on the nose and/or cap, such that when a predetermined force acting to open the vent arm from the closed position is exceeded the weakened region or regions collapses to expose the or each projection (37) which penetrates the nose and/or cap covering it and engages the other of the end cap/nose portions to immobilise the stay (1). A stay as claimed in claim 1, wherein the weakened region (39) incorporates at least one aperture through the nose portion (21). A stay as claimed in claim 1 or claim 2, wherein the nose portion (21) is asymmetric. A stay as claimed in any preceding claim, wherein the nose portion (21) comprises a mounting aperture (23) for receiving a rivet (25) passing through the vent arm (7), in use, to attach the nose portion (21) to the vent arm (7). A stay as claimed in claim 4, wherein the nose portion (21) further comprises a spigot (27) for engaging a recess or aperture (29) in the vent arm (7) to assist in retaining the nose portion (21) in a fixed position relative to the vent arm (7). A stay as claimed in any preceding claim, wherein the nose portion (21) further comprises a wall (33) defining a recess (35) shaped to receive the free end of the vent arm (7), the wall (33) being attached to a body portion (31) of the nose portion (7) by the weakened region (39) such that the wall (33) collapses when the predetermined force is exceeded. A stay as claimed in any preceding claim, wherein the nose portion (21) is formed from plastics material. A stay as claimed in claim 7, wherein the nose portion (21) is a one-piece moulding. A stay as claimed in any preceding claim, wherein the projection (37) is formed integrally with the vent arm (7). A stay as claimed in any preceding claim, wherein the end cap (9) includes a base (41), side walls (45) and a top cover (47) to prevent unwanted removal of the nose portion (21) from the end cap (9) by lifting of the nose portion (21) out of the end cap (9). A stay as claimed in any preceding claim, wherein the weakened region incorporates at least one recess in the end cap (9). A stay as claimed in any preceding claim, wherein the end cap (9) is asymmetric. A stay as claimed in any preceding claim, wherein the end cap (9) comprises a main cap and an insert adapted to fit into the main cap, the insert being designed to collapse when the predetermined force is exceeded. A stay as claimed in claim 13, wherein both the main cap and the insert comprise a mounting aperture for receiving a rivet passing through the support track (3) to attach the end cap (9) to the support track (3). A stay as claimed in claim 13 or claim 14, wherein the main cap is formed from metal. A stay as claimed in any one of claims 13 to 15, wherein the insert is formed from plastics material.

Inventors: DEANE ANDREW COLIN, DEANE, ANDREW COLIN
Applicants: SECURISTYLE LTD, SECURISTYLE LIMITED
Application year: 1993
Main classification: E05D15
IPC codes: E05D15, E05D11