GB2263934A - Releasable safety catch - Google Patents

Abstract

The releasable safety catch for use with opening panels, particularly windows, comprises a base plate 110 having an abutment 50, a catch 118 mounted to pivot relative to the base plate 110 and movable between an open and a closed condition relative to the base plate, the catch 118 having an abutment portion 120 engageable with the abutment 50 to limit pivotal movement of the catch 118 in one arcuate direction, resilient means biasing the abutment portion 120 towards the abutment 50, and the resilient means 135 having a terminal portion 132 always to the same side of the abutment 50 as the abutment portion 120. With this arrangement the base plate 110 is subjected to forces in only one angular direction and thus the base plate 110 is less likely to become free from the window frame. <IMAGE>

Description

RELEASABLE SAFETY CATCH FIELD OF THE INVENTION This invention relates to a releasable safety catch, and particularly to a releasable safety catch for the windows of multi-storey buildings such as high-rise flats. The catch can however be useful for windows at or below ground level, and for "opening panels" other than windows.

BACKGROUND TO THE INVENTION The safety problems associated with upper-storey sash windows in high-rise flats have long been recognised, and have been highlighted by reports of children opening such windows and falling from considerable heights. It has however proved unacceptable to the occupants to have the windows permanently sealed and unopenable.

Children also fall from windows at ground level, or below i.e.

basement windows.

An effective safety catch is thus required, normally operable to hold the window in a partly opened condition, but which is releasable to allow the window to be fully opened. To release the safety catch should require more manual dexterity and skill than a young child possesses.

Usefully the safety catch will be suitable for use not only on side hung windows, but also on a "tilt/turn" window arrangement wherein the window is alternatively openable as a side hung or a top hung window.

Furthermore it is now becoming increasingly common to have fully reversible windows, which can be swung about a horizontal central axis to permit cleaning from the inside of the dwelling of the normally outer surface of the glass. However, there are reports of people, particularly elderly people, pressing the window to swing it about its axis and perhaps themselves being carried on the window, and falling from the building.

Again an effective safety catch is required, perhaps easier to operate than a "childproof" catch but nevertheless in normal operation preventing full rotation of the window. Desirably this catch will have some components in common with the "childproof" catch.

DESCRIPTION OF THE PRIOR ART A known releasable safety catch is shown in Fig.l (top view) and Fig.2 (bottom view); the surfaces seen in Fig.l are herein referred to as upper surfaces, whilst those seen in Fig.2 are referred to as lower surfaces.

The catch of Figs.l and 2 is shown in the "open" condition.

The arm can be moved in direction "X" towards the closed condition.

The catch includes a base plate having a first securement formation adjacent one edge and a second securement formation adjacent an opposed edge, a pivot stem upstanding from the base plate, a stop member upstanding from the base plate, an arm having a central slot with a side entrance part way along the length of the slot, the arm being pivotally mounted on the pivot stem, a spring having coils encircling the pivot stem and having opposed tail terminal portions, with a first tail terminal portion engaged with the arm and a second tail terminal portion engaging the stop member whereby the stop member provides a continuous tail abutment for the second terminal tail portion and an intermittent impact abutment for the arm.

To open the window fully, it is necessary to release the stem of a headed retainer from the slot, through the slot side entrance.

In the known embodiment the pivot stem is headed, to help locate the arm.

There are a number of disadvantages with this known releasable safety catch. The stop member is a pin, partly encircled by the second tail terminal portion, so that the spring needs special tail formations at both ends; these formations include parts in perpendicular planes, so adding to complexity and cost in both manufacture and assembly. The additional forming of both spring terminal portions introduces an additional potential failure or fatigue area. At any position along the pin the impact force between the arm and the upstanding pin is effectively point contact, acting along a single (upstanding) line, and with high unit loading on both the pin and arm.The upstanding pin is pressed in one direction by the spring tail and is impacted in the opposite direction by the arm abutment surface; the intermittent impact force tends to loosen the pin from its mounting, whilst the constantly present spring force provides a return force, tending to urge the pin back towards the vertical i.e to swing the pin about its own axis and further loosen the pin from its mounting. In normal use, with the pin connected to the base plate and the base plate secured to an opening sash (or to the window frame) by screws or the like in and cooperating with the securement formations, both forces tend to pivot the base plate (but in opposite angular directions) about its (bottom) side edges and so angularly about its longitudinal axis (that axis extending between the securement formations), and tending to lift and so release both screws.

STATEMENT OF THE INVENTION We propose an improved releasable safety catch which avoids or reduces the above disadvantages.

Thus according to one feature of the invention we provide a a base plate having a first securement formation adjacent one edge and a second securement formation adjacent an opposed edge, a pivot stem upstanding from the base plate, a stop member upstanding from the base plate, an arm having a central slot with a side entrance part way along the length of the slot, the arm being pivotally mounted on the pivot stem, a spring having coils encircling the pivot stem and having opposed tail terminal portions, with a first tail terminal portion engaged with the arm and a second tail terminal portion engaging the stop member whereby the stop member provides a continual tail abutment for the second terminal tail portion and an intermittent impact abutment for the arm characterised in that the second tail portion is substantially linear.

According to a further feature of the invention we provide a releasable safety catch which includes a base member having a first securement formation adjacent one edge and a second securement formation adjacent an opposed edge, an arm pivotally mounted to the base member inwardly of said securement means, the arm having an impacting surface, a first abutment engageable by the said impacting surface, a spring having first and second terminal tails, the said first tail urging the arm in one angular direction relative to the base member to effect engagement between the impacting surface and said first abutment, a second abutment engageable by the said second tail of the spring characterised in that said first and said second abutments face one of the first and second securement means and face away from the other of said securement means.

Preferably the base member is an elongate base plate, and the first and second abutments lie across the upper surface of the baseplate (transverse to the defined longitudinal axis of the base plate), and extend towards opposed side edges thereof.

Preferably the two abutment surfaces are on a single member upstanding from and integral with the upper surface of the baseplate and extending completely thereacross.

One advantage of this arrangement is that in use the intermittent impact forces from the arm, and the continuous reaction force from the second spring terminal tail tend to lift upwardly only one of the securement means whilst pressing the other securement means downwardly towards the sash (or window frame) to which the catch is secured. The impact force between the arm abutment surface and the abutment surface of the integral member is spread over areas of these surfaces, to avoid impact unit loading.

A further advantage of this improved releasable safety catch is that it can be modified to suit various window installations, including the normal side or top hung windows, reversible windows having a central pivot, and the tilt/turn windows.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying drawings, in which : Fig.l is a top plan view of a known releasable safety catch, and an associated headed peg, intended for a side hung or top hung window, the stem of the headed peg being received in the central channel of the pivotted arm; Fig.2 is a bottom plan view of the releasable safety catch of Fig.l; Fig.3 is a perspective view of a releasable safety catch and associated headed peg, in accordance with the invention and suitable for a side hung or top hung sash window; Fig.4 is of an alternative embodiment of releasable safety catch; Fig.5 is of a further alternative embodiment of releasable safety catch;; Fig.5a is of the headed peg, suitable for use with the embodiment of Fig.5, and showing an enlarged view of the coil spring; Fig.6 is of a further alternative embodiment of pivotal arm suitable for use in a releasable safety catch for a reversible sash window; Fig.7 is an exploded perspective view of a base plate and separate abutment piece for affixing thereto; and Fig.8 is a side section of an alternative base plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings like numbers represent like parts.

The prior art releasable safety catch of Fig.1 and Fig.2 includes a base plate 10, generally rectangular in plan i.e. of a length greater than its width. Towards one end of the baseplate is a first securement formation 12, and towards the other or opposed end of the baseplate is a second securement formation 14. In use, screws or the like (not shown) are fitted through and to the securement formations 12,14 to retain the base plate to a window frame, though in some applications the baseplate may be secured to the opening window (sash). Extending between securement formations 12,14 is the (hypothetical) base plate longitudinal axis "A".

Upstanding from the base plate 10 is a pivot stem (not seen, being concealed by an arm 18), the pivot stem having a head 16.

Arm 18 can pivot about the pivot stem. Arm 18 has an impact abutment surface 20 engageable with an abutment surface on a pin 22 to define the maximum window opening movement permitted by the catch; pin 22 is also upstanding from the (upper) surface of the base plate.

In the closed position of the window, arm 18 will lie substantially parallel to the longitudinal axis "A". Figs.l and 2 show the arm 18 in a partially opened window condition.

A torsion spring has a first terminal tail portion 30, and a second terminal tail portion 32, with intermediate coils (not seen, but note Fig.5) wrapped around the pivot stem between the base plate 10 and arm 18. A spacer (not shown) is fitted around the pivot stem, and within the coils of the spring, to space the arm 18 from the base plate 10. Terminal tail portion 30 is partially wrapped around a side edge 18a of arm 18, whilst terminal tail portion 32 is partially wrapped around pin 22; terminal tail portion 30 is perpendicular, or nearly so, to terminal tail portion 32, extending upwardly as viewed (out of the paper).

The torsion spring urges the arm impact abutment surface 20 towards and against the pin abutment, and such impact occurs when the window handle conventionally fitted has been moved- to its window-release position, and the window opened. The impact force will usually be supplemented by a manually-derived impact force as the window is pushed (by its handle) towards its open condition, with the shank 42 (Fig.2) of headed peg 40 sliding in central slot 44 of arm 18 towards limit surface 46. Headed peg 40 is retained by way of securement formations 47,49 in its mounting base 45.

Alternatively, or furthermore, as arm 18 is manoeuvered to bring side entrance 48 for central slot 44 into alignment with shank 42, to allow the arm to be pivotted clear of shank 42, so releasing the safety catch and allowing the window to be fully opened, the torsion spring acts to urge the impact surface into engagement with the pin abutment. On such impact, the base plate 10 tends to pivot about its lower longitudinal edge 28, and thus angularly in direction "B" relative to the longitudinal axis "A" to lift the screws etc. holding the first and second securement means 12,14. The tail terminal end 32 in contradistinction applies a steady force tending to pivot the base plate 10 about its lower longitudinal edge 29, and thus angularly in direction "C" relative to the longitudinal axis "A".

The intermittent force impacts higher on the pin than the steady "opposing" force from tail terminal portion 32.

In the arrangement of Fig.3, according to the invention, the impact abutment surface and the spring abutment surface are to one side 51 of an upstanding block 50 from base plate 110.

Second tail terminal portion 132 is substantially linear; first tail terminal portion 130 is of angled configuration, but can now be of a more complicated form with a part 133 lying over the upper surface of the arm.

Thus both the intermittent impact force and the steady spring reaction force tend to urge the block in a single direction, towards the first securement formation 112 and away from the second securement formation 114.

The steady and impact forces tend to lift the second securement formation 114, but press the first securement formation 112 towards the window frame (or sash), to provide greater security i.e. the baseplate tends to pivot in one angular direction about a lateral axis, rather than in both angular directions about the longitudinal axis. Thus the base plate 110 is less likely to become free from the window frame, which of course would negate the purpose of fitting a safety catch.

The base plate 110 can be made substantially shorter than the known base plate 10, with the innermost end 44a of the central slot 44 overlying the securement formation 114 rather than the outermost end 44b (or limit surface 46), overlying securement formation 114.

As usual the arm 118 includes a central slot 44, with a side entrance 48 part way alona its length. Shank 42 of headed peg 40 is received in this slot, and upon normal opening of the window travels to limit surface 46, to hold the window in a partly open condition. To fully open the window, the user needs to slightly close the window to permit the arm to be pivotted away from shank 42, which requires some manual dexterity and skill, not available to a young child.

In the embodiment of Fig.4, the impact abutment surface 120 of the arm 218 is substantially flat, so that when in abutment with the block 50, the impact force is spread over enlarged contact areas of the arm 218 and the block 50, reducing the unit loading for both. Furthermore, a second abutment surface is provided (120a) so that the arm can be used for handed windows. In an alternative embodiment such as that of Fig.3 the first and second abutment surfaces can be of different lengths and at different angles to the axis A, for alternative uses with different base plates 110.

Surface 121 between the abutment surfaces 120,120a can be straight as shown, or convex.

The known releasable safety catch of Fig.l has an extended baseplate 10. When the window is in the closed condition, the arm 18 lies substantially parallel with the baseplate 10, and the head of the (standard) headed peg 40 lies between the facing surfaces of the baseplate 10 and the arm 18. In use with the various types of window frame available, it is required that the length of the headed peg 40 be chosen to allow this accurate fit, for each of the various window types i.e. the available gap between the frame and the sash into which the releasable safety catch and peg can be fitted is made different by the proprietary window manufacturers.

It is an additional feature of my invention that, since in the closed window condition, the projected area of the headed peg 40 falls outside the baseplate 110, the length of the headed peg 40 is not so critical, and fewer alternative peg lengths need to be provided.

In the embodiment of Fig.5, a pivot stem 115 is mounted on an alternative base, suited to a known tilt/turn window, to limit the tilt movement. The block 150 has two extensions 150a,150b which support the pivot stem 115 at both ends, rather than in cantilever as in the embodiments of Fig.3 and Fig.4. Thus the arm 18,118 projects in a plane away from the upper surface of the base plate rather than parallel to it. The mounting base 145 of peg 140 is of L-shape, with a transverse flange mounting the shank 142, which therefore in this embodiment extends perpendicularly to the securement portions 147,149, and permits a third securement portion 148 to be included. In this embodiment, two spacers (not shown) are required, to maintain the arm 18,118 centrally between the extensions 150a,150b.

The torsion spring is better seen in the component view of Fig.5a; it has a first terminal tail portion 130 with extension 133, and a second terminal tail portion 132, and intervening coil turns 135. In Fig.5 the extension 133 is hidden behind arm 118.

In the embodiment of Fig.6, a modified arm 318 is shown, suited to act as a catch for a central pivotted reversible window.

Since the external window surface will be cleaned when the window has been rotated nearly 180 degrees, the length of arm 218 is made significantly smaller. The arm can be used with the base plate of any of the embodiments of Figs 3-5, and the central slot 144 can accommodate either of the headed pegs 40,140.

In a manufactured example of the Fig.4 embodiment, the base plate 110 is made from die-cast zinc alloy, and is 3mm thick, 50mm long and 16mm wide; the block 50 extends fully across the base plate and upstands 5mm from the upper surface; the shank of pivot pin 15 is made from 5.3mm diameter stainless steel, with an 8mm diameter head, and is 11.6mm long; the spacer is an annulus of stainless steel, though it could equally be nylon or white acetal, with an inner diameter of 5.5mum, an outer diameter of 8mm, and a length of 3.0mm; the arm 18,118 is made from 2.65mm thick stainless steel, 81.5mm long and 16mm wide; the central slot 44 is 6mm wide and 52mm long; the side entrance 48 is 8mm wide.

In an alternative embodiment, the base plate 110 is made from stainless steel, with a separate die-cast abutment piece 250 of zinc alloy held by two rivets, as indicated in the exploded view of Fig.7. The rivet pegs 53 are formed integral with the abutment piece 250, and fit in holes 252. The rivet pegs are preferably round in cross-section but alternatively are square or rectangular.

Pivot stem 140 fits in hole 141 (Fig.8). As seen in the comparison between Fig.7 and Fig.8 the positioning (and size) of the abutment rivet holes 252, the pivot rivet hole 140 and the securement assemblies 112,114 can be selected according to the application, as can whether abutment 250 extends completely across base plate 210.

Claims (16)

1. A safety catch assembly comprising a base plate having an abutment, a catch mounted to pivot relative to the base plate and movable between an open and a closed condition relative to the base plate, the catch having an abutment portion engageable with the abutment to limit pivotal movement of the catch in one arcuate direction, resilient bias means urging the abutment portion towards the abutment, the resilient bias means having a terminal portion always to the same side of the abutment as the abutment portion.

2. An assembly as claimed in claim 1 in which the abutment portion and the teminal portion engage spaced abutment surfaces of the abutment, the abutment surfaces being co-planar.

3. An assembly as claimed in claim 1 or claim 2 in which the base plate carries a pivot stem, the catch being mounted on the pivot stem, the bias means extending between the catch and the abutment and acting to urge the abutment further from the pivot stem.

4. An assembly as claimed in any of claims 1-3 in which the abutment and the pivot stem upstand from the base plate, the base plate having two securement formations, the abutment and pivot stem being between the securement formations.

5. An assembly as claimed in claim 4 when dependent upon claim 2 in which the abutment surfaces face towards one of the securement formations and away from the other.

6. An assembly as claimed in any of claims 1-5 in which the abutment is integral with the base plate.

7. An assembly as claimed in claim 6 in which the abutment is part of the base plate, and the pivot stem extends parallel thereto.

8. An assembly as claimed in claim 7 in which the pivot stem is carried by extensions which support the pivot stem at both ends.

9. An assembly as claimed in any of claims 1-5 in which the catch has a central slot with a lateral entrance, the slot having a first end and a second end, the first end being nearer to the abutment than the second end, only the first end of the slot overlying the base plate in the closed condition of the catch.

10. An assembly as claimed in claim 9 in which the said first end of the slot overlies a securement formation in the closed condition of the catch.

11. A base plate for the assembly of claims 1-10 which has a first securement formation adjacent one edge and a second securement formation adjacent an opposed edge, a pivot stem upstanding from the base plate, a stop member upstanding from the base plate, the pivot stem being adapted pivotally to mount an arm having a central slot with a side entrance part way along the length of the slot, the pivot stem being adapted to mount resilient bias means comprising a spring, the spring having coils sized to encircle the pivot stem and having opposed tail terminal portions, with in use a first tail terminal portion engaged with the arm and a second tail terminal portion engaged with the stop member whereby the stop member provides a continual tail abutment for the second tail terminal portion and an intermittent impact abutment for the arm, the second tail terminal portion being linear or substantially so.

12. A base plate as claimed in claim 10 which is elongate, the stop member being transverse to the longitudianl axis of the base plate.

13. A safety catch constructed and arranged substantially as described with reference to Fig.3 or Fig.4 or Fig.5 of the accompanying drawings.

14. A headed peg constructed and arranged substantially as described with reference to Fig.5a of the accompanying drawings.

15. A pivotal arm constructed and arranged substantially as described with reference to Fig.6 of the accompanying drawings.

16. A base plate constructed and arranged substantially as described with reference to Fig.8 of the accompanying drawings.