GB2187498A

GB2187498A - A door chain

Info

Publication number: GB2187498A
Application number: GB08605519A
Authority: GB
Inventors: Edgar John Wagstaff
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-03-06
Filing date: 1986-03-06
Publication date: 1987-09-09
Also published as: GB2187498B; GB8605519D0

Abstract

A door chain 14 has one end fitting 17 which can be released, normally by way of a key, from outside the door. The end fitting 17 is located in a rotatable keeper 18 which has an open-ended slot 20, 21 which normally has its open end upwards. By operation of the key from outside the door 10, the keeper 18 is inverted and the open end points downwards, allowing the chain end fitting 17 to drop out of the keeper. <IMAGE>

Description

SPECIFICATION A door chain This invention relates to a door chain of the type used as a security precaution on a front door.

Door chains are used to allow the door to be opened to a limited extent, on the chain, so that people on opposite sides of the door can see one another and converse without allowing the person outside the opportunity to force the door completely open and obtain access through the door. Conventionally the chain can easily be engaged or disengaged from the inside of the door.

One problem with a door chain of this type however is that it effectively prevents access from outside without assistance from within.

For example an elderly person living alone will often not use the chain, because it would then be impossible for anybody else to get into the house should the occupant fall ill or be injured.

According to the present invention, there is provided a door chain comprising a flexible link (which will normally be a chain), a shackle attached to one end of the flexible link, a boss attached to the other end of the flexible link and a keeper, the shackle being adapted to be fitted to a door frame and the keeper being adapted to be fitted to the door (or vice versa), wherein the keeper has an open-ended slot for receiving the boss and is mounted so that it can be rotated from outside the door between a position where the open end of the slot is above the bottom of the slot and a position where the open end of the slot is facing downward, so that the boss drops out of the slot.

Preferably the keeper is mounted at the end of the barrel of a cylinder lock so that a key can be inserted into the lock cylinder from outside the door and turned, whereupon the keeper turns to release the boss. In its normal, 'locked' position, the slot in the keeper is preferably arranged generally vertically. The open end of the slot is preferably at the top end of the slot, on the side thereof away from the edge of the door. The top of the vertical slot can be bounded by a wall, so that when the door is opened on the chain, it is not possible to move the chain and cause the boss to fall out.

The invention will now be further described, by way of example, with reference to the accompanying drawing in which: Figure 1 shows a door and door frame with a door chain according to the invention in position; Figures 2 and 3 show alternative designs of keepers; Figure 3a shows the keeper of Fig. 3 in a different position; and Figure 4 is a section through a door on which a keeper is mounted, the section passing.through the keeper on the line IV-IV.

Fig. 1 shows part of a door 10 and part of a door frame 12. A chain 14 extends between a shackle 16 on the frame and a boss 17 fitted in a keeper 18 on the door. The chain 14 and shackle 16 are conventional and will not be further described. The keeper however will be described in detail.

The two alternative keeprs 18a and 18b in Figs. 2 and 3 are both shown in their normal positions. One has a vertical slot 20 and the other has a parallel-sided curved slot 21. Both have an opening 22 near the top of the slot.

The slot walls extend over the tops of the slots. In use, the keeper is mounted so that the opening 22 faces away from the adjacent edge of the door. The edges of the slots have an undercut as illustrated by dotted lines in Figs. 2 and 3 and as can be seen also in the sectional view of Fig. 4. Fig. 3 also shows in dotted lines the position of the boss 17 when the chain is in place.

Fig. 3a shows the keeper of Fig. 3 inverted to release the boss. The arrow 24 shows the path taken by the boss 17 as it drops out. In this example the keeper has been turned clockwise through about 135".

Fig. 4 shows a section through the door.

On the outside 26, a conventional cylinder lock bezel 28 is fitted. The lock barrel 30 passes through a circular aperture through the thickness of the door and is secured by bolts which pass through a plate 32. An operating bar 34 then projects from the inside of the door. The keeper 18 is rotatably mounted on a bearing plate 36 and has a recess in which the operating bar engages. When the plate 36 is secured to the door, the keeper 18 and the bar 34 are in permanent engagement.

When the correct key is fitted in the lock cylinder and turned, the keeper is turned by the operating bar until the boss drops out.

The boss will drop out which ever direction the key is turned.

This chain will be used in the same way as a conventional chain. The person inside the house will place the boss 17 in the slot 20. If the door has to be opened whilst the chain is on, the top slot wall, together with the fact that the chain will inevitably be pulled taut, will obstruct any attempt by the person outside to disengage the chain.

If access has to obtained from outside in an emergency, the key for the lock on the keeper will be needed, and this could, for example, be left with a neighbour. With this key, the chain can be simply disengaged from the outside. Thus the occupant of a house with a chain as described can always put the chain in place when they are inside, without worrying about what will happen if they are unable to get to the door to open it in an emergency.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A door chain This invention relates to a door chain of the type used as a security precaution on a front door. Door chains are used to allow the door to be opened to a limited extent, on the chain, so that people on opposite sides of the door can see one another and converse without allowing the person outside the opportunity to force the door completely open and obtain access through the door. Conventionally the chain can easily be engaged or disengaged from the inside of the door. One problem with a door chain of this type however is that it effectively prevents access from outside without assistance from within. For example an elderly person living alone will often not use the chain, because it would then be impossible for anybody else to get into the house should the occupant fall ill or be injured. According to the present invention, there is provided a door chain comprising a flexible link (which will normally be a chain), a shackle attached to one end of the flexible link, a boss attached to the other end of the flexible link and a keeper, the shackle being adapted to be fitted to a door frame and the keeper being adapted to be fitted to the door (or vice versa), wherein the keeper has an open-ended slot for receiving the boss and is mounted so that it can be rotated from outside the door between a position where the open end of the slot is above the bottom of the slot and a position where the open end of the slot is facing downward, so that the boss drops out of the slot. Preferably the keeper is mounted at the end of the barrel of a cylinder lock so that a key can be inserted into the lock cylinder from outside the door and turned, whereupon the keeper turns to release the boss. In its normal, 'locked' position, the slot in the keeper is preferably arranged generally vertically. The open end of the slot is preferably at the top end of the slot, on the side thereof away from the edge of the door. The top of the vertical slot can be bounded by a wall, so that when the door is opened on the chain, it is not possible to move the chain and cause the boss to fall out. The invention will now be further described, by way of example, with reference to the accompanying drawing in which: Figure 1 shows a door and door frame with a door chain according to the invention in position; Figures 2 and 3 show alternative designs of keepers; Figure 3a shows the keeper of Fig. 3 in a different position; and Figure 4 is a section through a door on which a keeper is mounted, the section passing.through the keeper on the line IV-IV. Fig. 1 shows part of a door 10 and part of a door frame 12. A chain 14 extends between a shackle 16 on the frame and a boss 17 fitted in a keeper 18 on the door. The chain 14 and shackle 16 are conventional and will not be further described. The keeper however will be described in detail. The two alternative keeprs 18a and 18b in Figs. 2 and 3 are both shown in their normal positions. One has a vertical slot 20 and the other has a parallel-sided curved slot 21. Both have an opening 22 near the top of the slot. The slot walls extend over the tops of the slots. In use, the keeper is mounted so that the opening 22 faces away from the adjacent edge of the door. The edges of the slots have an undercut as illustrated by dotted lines in Figs. 2 and 3 and as can be seen also in the sectional view of Fig. 4. Fig. 3 also shows in dotted lines the position of the boss 17 when the chain is in place. Fig. 3a shows the keeper of Fig. 3 inverted to release the boss. The arrow 24 shows the path taken by the boss 17 as it drops out. In this example the keeper has been turned clockwise through about 135". Fig. 4 shows a section through the door. On the outside 26, a conventional cylinder lock bezel 28 is fitted. The lock barrel 30 passes through a circular aperture through the thickness of the door and is secured by bolts which pass through a plate 32. An operating bar 34 then projects from the inside of the door. The keeper 18 is rotatably mounted on a bearing plate 36 and has a recess in which the operating bar engages. When the plate 36 is secured to the door, the keeper 18 and the bar 34 are in permanent engagement. When the correct key is fitted in the lock cylinder and turned, the keeper is turned by the operating bar until the boss drops out. The boss will drop out which ever direction the key is turned. This chain will be used in the same way as a conventional chain. The person inside the house will place the boss 17 in the slot 20. If the door has to be opened whilst the chain is on, the top slot wall, together with the fact that the chain will inevitably be pulled taut, will obstruct any attempt by the person outside to disengage the chain. If access has to obtained from outside in an emergency, the key for the lock on the keeper will be needed, and this could, for example, be left with a neighbour. With this key, the chain can be simply disengaged from the outside. Thus the occupant of a house with a chain as described can always put the chain in place when they are inside, without worrying about what will happen if they are unable to get to the door to open it in an emergency. CLAIMS

1. A door chain comprising a flexible link, a shackle attached to one end of the flexible link, a boss attached to the other end of the flexible link, and a keeper, the shackle being adapted to be fitted to a door frame and the keeper being adapted to be fitted to the door (or vice versa), wherein the keeper has an open-mouthed slot for receiving the boss and is mounted so that it can be rotated from outside the door between a position where the open end of the slot is above the bottom of the slot and a position where the open end of the slot is facing downwards, so that the boss drops out of the slot.

2. A door chain as claimed in Claim 1, wherein the keeper is connected to a keyoperated lock such that when a key is inserted in the lock from outside the door, and is then turned, the keeper can be moved between the two said positions.

3. A door chain as claimed in Claim 2, wherein the lock is a cylinder lock, and the keeper is mounted directly on the rotatable barrel.

4. A door chain as claimed in any preceding claim, wherein the keeper is arranged such that when it occupies its first-mentioned position with the open end above the bottom of the slot, the open end faces away from the shackle.

5. A door chain substantially as herein described with reference to the accompanying drawings.