GB2178100A - Door safety chain device - Google Patents

Abstract

A door safety chain device including component parts secured to the door and to the door frame and including also a flexible element allowing the door to be opened only a very small amount when the device is in use. So that the device can be made very strong and extremely difficult to render inoperative, the flexible element is a length of chain or steel cable or the like (10) and is at least partly retractable into a housing (16) adapted to be fixed in position on the door or door frame. <IMAGE>

Description

SPECIFICATION Door safety chain device The invention relates to a safety chain device for doors, that is to say to a chain arrangement whereby a door can be opened only a very small amount to produce a gap through which a caller can be vjewed and his identity checked before the door is opened fully.

Door safety chains are used to give security against forced entry to domestic premises.

However, such chains are also used in banks, business premises and offices to guard against intruders.

A conventional safety chain is not adequate for preventing entry by a really determined intruder. The chain itself is visible when the door is opened by only the small amount allowed by the chain. The chain itself is usually not very robust so that it is a simple matter to sever it with a cutting tool, axe or heavy metal bar. The means whereby the component parts of a conventional safety chain are secured to the door and to the door frame are likewise not generally adequate to resist a determined attempt to force an entry.

The object of the invention is to provide a door safety chain device which will be very strong and extremely difficult to render inoperative.

According to the invention, there is provided a door safety chain device including a length of chain or steel cable or like flexible or articulated element retractable or at least partly retractable into a housing adapted to be fixed in position in or on a door surround and/or in or on the door, a free end of said length of chain or steel cable or like flexible or articulated element being attached to a means adapted for convenient handling and means, forming part of a catch arrangement, whereby it can be quickly and easily connected to a component part of the device permanently fixed to the door adajcent its free edge, or to the door surround, as the case may be.The means forming part of a catch arrangement whereby the length of chain or steel cable or like flexible or articulated element can be quickly and easily connected to the component part of the device permanently fixed to the door adjacent its free edge or to the door surround, as the case may be, will preferably be such that, when the device is in use and the door has been opened the small amount allowed by the device, the change of angle of said means relative to said fixed component part will have rendered it impossible for said means to be disconnected from said component part without first re-closing the door.The means forming part of a catch arrangement whereby the length of chain or steel cable or like flexible or articulated element can be quickly and easily connected to the component part permanently fixed to the door or door surround, as the case may be, may be an arrangement taking the form of a hook-like arrangement or dovetailed joint arrangement held in engagement by the tension in the flexible element when the device is in use, or alternatively a pin and eye arrangement. A part of the catch arrangement may be a catch element on a pivotable part of the component permanently attached to the door surround. In this case, the pivotable part may be arranged to swing, against the force of a spring, outwardly towards the door when the door is opened with the safety chain device in the locked or operative position.On the other hand, the means forming part of the catch arrangement whereby the length of chain or steel cable or like flexible or articulated element can be quickly and easily connected to the component part permanently fixed to the door or door surround, as the case may be, may include a manually operable latch device which, when in an operative position, prevents the hook-like arrangement or dovetailed joint arrangement from becoming disengaged from the component part permanently secured to the door or door surround.

The length of chain or steel cable or like flexible or articulated element may be connected at one end to a rotatable shaft mounted in the housing. Alternatively, the housing may be of shallow and elongate form within which the length of chain or steel cable or like flexible or articulated element is located in extended condition.The housing or other component part of the device fixed to the door surround may be such that when the device is in use and the door Has been opened the small amount allowed by the length of chain or steel cable or like flexible articulated element, the latter will not be visible from outside by virtue of the design or because it will be completely masked by the housing or other component part, as the case may be, so that the severing of the length of chain or steel cable or like flexible or articulated element from outside the house or other premises will be virtually impossible. The component part of the device to which the free end of the length of chain or steel cable or like flexible element can be connected or the housing into which the length of chain or steel cable or like flexible or articulated element is retractable, as the case may be, may be fixed only to the door.On the other hand, where very high security of required, the part fixed to the door may be formed as part of, or secured to, a metal band extending across the width of the door and fixed by way of a hinge to the door surround adjacent the hinged edge of the door or the housing may extend across the door and be fixed to or in the door surround adjacent to the hinged edge of the door and so constructed that the door may be opened and closed in a normal manner.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a diagrammatic view of a door fitted with a safety chain device embodying the invention, Figure 2 is a sectional view on the line 2-2 in Figure 1, the door being shown slightly ajar to the extent allowed by the safety chain device, Figure 3 is a view similar to Figure 2, but with the door closed, Figure 4 is a view similar to Figure 1, which illustrates a possible modification which will be referred to, Figure 5 is a view similar to Figure 2 of a different construction of door safety chain device embodying the invention, Figure 6 is an exploded view of a housing part thereof, Figure 7 is a perspective view of a housing part of a still further construction of door safety chain device embodying the invention, Figure 8 is a perspective view of the rear of the housing part of Figure 7, Figure 9 is a part-sectional view of the device in use, with the door closed, Figure 10 is a similar view with the door open the small amount allowed by the safety chain device, Figure 11 is a view similar to Figure 2 of a still further construction of door safety chain device embodying the invention, Figure 12 is a view in the direction of the arrow 12 in Figure 11, Figure 13 is a sectional view on the line 13 13 in Figure 11, and Figure 14 is a perspective view of the Figure 11 construction.

Referring now to Figures 1 to 3 of the drawings, the door safety chain device there illustrated includes a flexible chain element 10 which is formed of a plurality of links 12 articulated together so that the flexible chain element is wide in relation to its thickness, as shown. The flexible chain element is connected at one end to a rotatable shaft 14 which is mounted in a housing 16, the housing being adapted to be clamped in position, as shown, in or on a door surround adjacent the free edge of the door. The rotatable shaft is acted on by a coil spring (not shown) which acts to take up slackness in the length of flexible chain element.

A free end of the length of flexible chain element is provided with a handle 20 and with means whereby it can be quickly and easily connected to a component part generally indicated 22 permanently secured to the door adjacent its free edge, such means in the drawing being shown to be constituted by a hooklike arrangement 24 which is held in engagement by the tension in the length of flexible chain element.

Referring in particular to Figures 2 and 3, it will be seen that the housing 16 is of rectangular cross sectional shape and that the length of flexible chain element emerges from within the housing through an elongate aperture 26 in the surface of the housing which is located in a plane parallel to the face of the door and located forwardly of the face of the door when the door is shut. The arrangement is such that when the means associated with the handle have been engaged with the part 22 secured to the door, the flexible chain element extends around the side wall of the housing as shown in chain-dotted lines in Figure 2. As the door is opened, the flexible chain element assumes the position shown in full lines.The length of the flexible chain element is such that it arrests the opening of the door before a visible gap appears between the edge of the door and the housing to a viewer looking substantially in the direction of arrow A. When the device is in use and the door has been opened by the householder or other user through the small amount allowed by the flexible chain element, the latter is completely hidden from a person on the other side of the door by the housing so that the severing of the flexible chain element from outside the room, house or other premises is virtually impossible. When the device is not in use and the length of flexible chain element has been retracted into the housing as shown in Figure 3, the handle 20 is presented at a convenient angle projecting from the housing so that the device can very quickly be brought into use.

The housing 16 can be either secured to the timber door surround, or to the reveal, or to both. In Figures 2 and 3, the housing is shown to be secured to the timber door surround by wood screws 28 and to the reveal by Rawlbolts 30 set in the masonry or brickwork. In some circumstances it might be necessary to recess the housing partly into the reveal to provide clearance for the edge of the door as it swings open.

The component part 22 is shown in Figures 2 and 3 to be secured only to the door by means of wood screws 36. In most cases this method of fixing will be adequate, but if greater strength is required it can be set partly into the woodwork or framing of the door.

However, in Figure 4 there is illustrated a modification in which the component part 22 is in addition secured to a metal band 32 which extends across the width of the door and is secured to the door by means of wood screws 37 and also by way of a hinge 34 to the reveal of the door opening by Rawlbolts 35 adjacent the hinged edge of the door. This arrangement will give the degree of security which might be required in a bank or in offices where determined criminal attacks might be expected.

Thus there is provided a door safety chain device which it is thought will be a considerable improvement on conventional safety chains.

Referring now to Figures 5 and 6 of the drawings, the rather different construction of door safety device there illustrated includes three separate lengths of flexible chain element 10 each of which is formed of a plurality of links 12 articulated together. The lengths of flexible chain element are retractable into a housing generally indicated 160 which in this case is of flat and elongate form and which is shown to be clamped in position on a door adjacent its free edge. As shown in Figure 6, a main body part 162 of the housing has been formed as a pressing with respective grooves 164 for the reception of the lengths of flexible chain element. The ends of the lengths of flexible chain element within the body part are connected to a retaining bar 166 which extends through aligned slots 168 in the walls of the grooves as shown.The lengths of the slots 168 determines the extent by which the lengths of flexible chain element can be withdrawn from the housing and subsequently retracted back into the housing. A pair of tension springs 170 for retracting the lengths of flexible chain element are located in the grooves which open from the underside of the main body part. One end of each spring is connected to the retaining bar 166 where this extends across the groove in which the spring is located. The other ends of the springs are connected to respective downturned tang or barb portions 172 which are shown to have been pressed out of the metal of the main body part. A metal cover 174 which is fitted over the main body part when in use hides the latter from view and prevents the lengths of flexible chain element from becoming disengaged from the grooves in which they are slideable.

The free ends of the lengths of flexible chain element are pivotally connected, by means of a stout pivot pin 176, to a handle 120. As shown in Figure 5, a side edge of the handle is provided with a hook formation which can be quickly and easily connected to a component part generally indicated 122 which is permanently secured to the door sur round. The component part 122 is in the nature of a stout metal box an opening in which faces away from the door surround.A vertical detent member 124 is located near to the mouth of the opening in the metal box and the arrangement is such that, as shown in full lines in Figure 5, with the door closed, the hook formations of the handle can be engaged with the detent member but such that, when the door has been partly opened to the extent allowed by the sliding movement of the lengths of flexible chain element from the housing, as shown in chain-dotted lines, the handle is held captive. This is ensured by the fact that an abutment pin 126 is located be hind the detent member, as shown, so that when the angle of the handle has been changed by the direction of the reaction from the lengths of flexible chain element having altered, it is impossible to disengage the handle from the detent member. It is necessary to re-close the door before the handle can be disconnected from the component part 122.

As in the case of the first described embodiment, when the device is in use and the door has been opened by the householder or other user through the small amount allowed by the lengths of flexible chain element, the latter are completely hidden from a person on the other side of the door by the component part 122, although of course it will be understood that the user has a clear view through the gap between the edge of the door and the door surround above and below the component part 122. Consequently, the severing of the lengths of flexible chain element from outside the room, house or other premises in which the device is used is virtually impossible.Also as in the first described embodiment, when the device is not in use and the lengths of flexible chain element have been retracted into the housing by the tension springs, the handle is held closely against the edge of the housing and has a neat appearance besides being in a position from which it can very quickly and easily be brought into use.

It will of course be understood that, in effect, the device is only as strong as the means by which its component parts are secured in position to the door and to the door surround (although of course the housing part could be secured to a metal band extending across the width of the door and connected by means of a stout hinge to the reveal of the door opening, substantially as shown in Figure 4). The means by which the component part 122 of the device is secured to the door surround is not shown in the drawing but this will preferably be by means of Rawlbolts into the surrounding masonry or brickwork and not only by wood screws into the woodwork.

Referring now to Figures 7 to 10, the still further construction of door safety device there illustrated is generally similar to that il lustrated in Figures 5 and 6, but the housing part is of somewhat simpler construction, be ing a single pressing in the form of a rectan gular door plate 260 with a major depression 262 pressed into its underside as shown in Figure 8. The three separate lengths of flexible chain element 10 are in this case articulated to a stop bar 264 which can abut one end of the depression 262 to limit the extent by which the lengths of flexible chain element can be withdrawn from the housing.Respective apertures 266 provided in an end wall of the depression enable the lengths of flexible chain element to emerge from within the housing for their ends remote from the stop bar to be articulated to the handle 120. (The handle 120 can be seen to be of similar form to the handle in the embodiment of Figures 5 and 6, except that it is provided with an additional projecting portion 268 which can more easily be grasped by the user). Three lengths of tension spring 170 are in this case provided for retracting the lengths of flexible chain element into the main body part. One end of each spring is connected to the stop bar 264. The other end of each spring is connected to the respective one of three hook elements formed on an anchorage member 270 welded within the main body part.

In addition to the major depression 262, the door plate is provided, adjacent an end portion 272 which wraps around an edge portion of the door, with a smaller depression 274 which houses a small permanent magnet 276.

The magnet serves to hold the handle in abutment with the housing part of the device when not in use, as shown in Figure 9. (It will be understood that when the housing part of the device is to be fitted to a door, the edge of the door will require to be rebated to receive the end portion 272 of the door plate and will require to be apertured to receive that part of the door plate defining the smaller depression 274).

As in the case of each earlier described embodiment, when the device is in use and the door has been opened by the householder or other user through the small amount allowed by the lengths of flexible chain element, the latter are completely hidden from a person on the other side of the door, as can be seen in Figure 10, although the user has a clear view through the gap between the edge of the door and the door surround above and below the device. It can also be seen in Figure 10 that as the lengths of chain element are drawn out from the housing, they can slide smoothly around the radiused corner of the door plate.

It will be seen from Figures 9 and 10 that the component part 122 which is permanently secured to the door surround is of a rather different shape to that illustrated in Figure 5.

However, like the earlier construction it is provided with a vertical detent member 124 in the form of a stout rod or bar extending between upper and lower wall members. Internal wall surfaces of the part 122 perform the function of the abutment pin 126 of the earlier construction, so that when the angle of the handle has been changed by the direction of the reaction from the lengths of flexible chain element having altered, it is impossible to disengage the handle from the detent member, As in the earlier described embodiment, it is necessary to re-close the door before the handle can be disconnected from the component part 122.

In Figure 9 it will be seen that the component part is shown to have been secured, against a wall surface or reveal in which the door frame is fitted, by round headed bolts. In chain-dotted lines there is indicated a hexagon headed portion of each bolt which has been used to tighten the bolt in position and which has then been broken off adjacent the half round surface of the head of the bolt so that the bolt can only subsequently be removed with the greatest difficulty.

It will of course be understood that it may not always be possible to bolt the component part 122 in exactly the position illustrated in the examples, that is to say within the reveal, because the door frame may be fitted too far forwards within the reveal or fill all the avilable space within the reveal. In such a case it will be necessary either to bolt the component part to a face of the wall adjacent the reveal or to a carrier bracket bolted to that surface of the wall. When fitted substantially as shown in the drawings, it may be necessary either to recess the component part slightly into the plaster or brickwork or alternatively to mount it on a hardwood backing (through which of course the bolts will extend into the brickwork).

Referring now to Figures 11 to 14, these illustrate a further improvement concerning the catch element of the device which engages the chain or other elongate element in the locked position of the device. This catch element is on a pivotable part of the component permanently attached to the door surround, which part is hingedly attached to a part fixed to the door surround. The pivotable part is arranged to swing, preferably against a spring force, outwardly towards the door when the door is opened with the safety chain device in the locked position. The advantages obtainable are that the elongate element can be better concealed and that the component attached to the surround can have abetter appearance.

Figure 11 shows how the part attached to the door surround has been modified, It takes a hinged form one leg Z of which is firmly attached to the door surround, while the second leg Y is hinged so that it can move around the arc A-B (Figure 11). The second leg has three open ended slots S1 (Figures 13 and 14).

The part X attached to the chains has been modified so that it is provided with a handle part in the form of a knob and with three retaining flat-headed pegs P which mate with the open ended slots in Y (Figures 12 and 13). The housing into which the lengths of flexible chain element are retractable is shown recessed into the door so that only a backplate part, which is secured to the door by screws is visible (see Figure 14). The backplate part of the housing is extended around the edge of the door and acts as a wear plate for engagement by the leg Y of the part attached to the door surround as the door is opened with the safety device in use.

Part Y is provided with a spring T in the hinge which causes the second leg always to rotate towards B and so when not in use the second leg lies close to the wall.

In use part X is lifted away from the face of the door permitting Y to be moved to position A. The retaining pegs on X are fitted into the open ended slots S1 in the part Y and held in engagement by the tension on the chains and the rotational torque on Y.

As the door is opened the chains attached to part X extend from within the housing and part Y moves towards B until the point where further movement is prevented by the chain stops. This process is reversed to disengage.

Disengagement is virtually impossible unless the door is closed.

The chains are completely masked.

When not in use, the part X is held in engagement with the face of the door by the three flat-headed pegs P being engaged in slots S2 in the backplate part of the housing.

Various other modifications may be made.

For example, the flexible chain element need not necessarily be formed in the manner described and illustrated; it could instead be formed either of woven wire or steel cable.

Indeed, the chain, woven wire or steel cable could quite well be set in a synthetic plastics material. In this case, the flexible chain element may have a natural tendency to roll up and this may render it unnecessary, if used in the construction illustrated in Figures 1 to 4, for the rotatable shaft to be acted on by spring means for taking up slackness in the flexible chain element. The means whereby the free end of the or each length of flexible chain element can be connected to the component part permanently secured to the door or permanently- secured to the door surround, as the case may be, may be varied in numerous ways. For example, instead of the handle being unable to be disengaged from the detent member only when its angle has been altered (as for example when the door has been opened to the extent allowed by the device) there could be provided a further manually operable latch element capable of being moved into position to retain the handle in engagement with the detent member before the door has been unlocked. On the other hand, the hook-like arrangement 24 may be replaced by a dovetailed joint arrangement or by some other similar sliding connection capable of being held in engagement by the tension in the flexible chain or like element or elements when the device is in use.

It will of course be understood that in a bank for example a door may be provided with two or more safety chain devices embodying the invention.

Claims (12)

1. A door safety chain device including a length of chairs or steel cable or like flexible or artitiNd ~iWst partly retractable into a housing adapted to be fixed in position in or on a door surround and/or in or on the door, a free end of said length of chain or steel cable or like flexible or articulated element being attachable to a means adapted for convenient handling and means, forming part of a catch arrangement, whereby it can be quickly and easily connected to a component part of the device permanently fixed to the door adjacent its free edge, or to the door surround, as the case may be.

2. A door safety chain device according to claim 1, in which the means forming part of a catch arrangement, whereby the length of chain or steel cable or like flexible or articulated element can be quickly and easily connected to the component part of the device permanently fixed to the door adjacent its free edge or to the door surround, as the case may be, is such that, when the device is in use and the door has been opened the small amount allowed by the device, the change of angle of said means relative to said fixed component part will have rendered it impossible for said means to be disconnected from said component part without first re-closing the door.

3. A door safety chain device according to either one of the preceding claims, in which the means, forming part of a catch arrangement, whereby the length of chain or steel cable or like flexible or articulated element can be quickly and easily connected to the component part permanently fixed to the door or door surround, as the case may be, is an arrangement taking the form of a hook-like arrangement or dovetailed joint arrangement held in engagement by the tension in the flexible element when the device is in use, or alternatively a pin and eye arrangement.

4. A door safety chain device according to claim 3, in which a part of the catch arrangement is a catch element on a pivotable part of the component part permanently attached to the door surround.

5. A door safety chain device according to claim 4, in which the pivotable part is arranged to swing, against the force of a spring, outwardly towards the door when the door is opened with the safety chain device in the locked position.

6. A door safety chain device according to any one of claims 1 to 3, in which the means forming part of the catch arrangement, whereby the length of chain or steel- cable or like flexible or articulated element can be guickly and easily connected to the component part permanently fixed to the door or door surround, as the case may be, includes a manually operable latch device which, when in an operative position, prevents the hook-like arrangement or dovetailed joint arrangement from becoming disengaged from the component part permanently secured to the door or door surround.

7. A door safety chain device according to any one of the preceding claims, in which the length of chain or steel cable or like flexible or articulated element is connected at one end to a rotatable shaft mounted in the housing.

8. A door safety chain device according to any one of claims 1 to 6, in which the housing is of shallow and elongate form within which the length of chain or steel cable or like flexible or articulated element is located in extended condition.

9. A door safety chain device according to any one of the preceding claims, in which the housing or other component part of the device fixed to the door surround is such that when the device is in use and the door has been opened the small amount allowed by the length of chain or steel cable or like flexible articulated element, the latter will not be visible from outside by virtue of the design or because it will be completely masked by the housing or other component part, as the case may be, so that the severing of the length of chain or steel cable or like flexible or articulated element from outside the house or other premises will be virtually impossible.

10. A door safety chain device according to any one of the preceding claims, in which the component part of the device to which the free end of the length of chain or steel cable or like flexible element can be connected or the housing into which the length of chain or steel cable or like flexible or articulated element is retractable, as the case may be, is fixed only to the door.

11. A door safety chain device according to any one of claims f to 9, in which, where very high security is required, the part fixed to the door is formed as part of or secured to, a metal band extending across the width of the door and fixed by way of a hinge to the door surround adjacent the hinged edge of the door or in which the housing extends across the door and is fixed to or in the door surround adjacent to the hinged edge of the door and so constructed that the door may be opened and closed in a normal manner.

12. A door safety chain device constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated by Figures 1 to 3, or Figure 4, or Figures 5 to 6, or Figures 7 to 10, or Figures 11 to 13 of the accompanying drawings.