GB2112442A - Emergency door lock - Google Patents

Abstract

A lock comprises a housing 10 and a locking member 11 movable between a locking position and an unlocking position by a carrier plate 12, the lock normally being operated by means of a key. Provided on the lock is an emergency unlocking device comprising a control member 26 which is slidable along guide bar 23 and biased by a spring 27 to unlock the lock by means of extension 34 of member 26 which acts on arm 37 of carrier plate 12. The control member 26 is normally prevented from sliding along guide bar 23 by means of a glass plate 30 which in an emergency can be broken to allow the spring 27 to act on member 26 and hence effect unlocking of the lock. <IMAGE>

Description

SPECIFICATION Locks The invention relates to locks and particularly to locks of the kind in which a locking member is movable by an authorised person (e.g. the holder of a key for the lock where it is key operated) between a locking position in which a locking member protrudes from a housing (e.g. for engagement with a catchplate on a door frame) and an unlocking position in which the locking member is retracted.

Difficulties can arise with such a lock if there is an emergency such as fire and an authorised person is not available to unlock the lock.

The invention provides a lock comprising a housing, a locking member movable between a locking position in which the locking member protrudes from the housing and an unlocking position in which the locking member is retracted into the housing, first control means operable by an authorised person (e.g. by means of a key) to move the locking member between the locking and unlocking positions, and second control means operable by any one in an emergency (e.g.

a smash glass device) to move the locking member from the locking position to the unlocking position.

The lock preferably includes a catch member which, when the locking member is in the locking position, holds the locking member in the locking position so that pressure on the locking member itseif is insufficient to return it to the unlocking position, the second control means including a device which first engages the catch member to release it and then moves the locking member to the unlocking position.

The first and second control means may be such that after the second control means has been operated to move the locking member to the unlocking position, the locking member cannot be returned to the locking position except by operation of the first control means.

The second control means may comprise a control device which is held in an inoperative condition against a bias (e.g. a spring device) by a frangible member such as a sheet of glass, but when the frangible member is broken the control device moves into an operative condition under the action of the bias.

A handle may be provided to assist movement of the control device into the operative position after the frangible member has been broken, for example in case the control device should stick slightly.

The control device may comprise a peg which Projects into the housing, movement of the peg from the inoperative condition to the operative condition causing the peg first to disengage the catch member and then to move the locking member.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which: Figure 1 is a cross-section through part of an embodiment of lock according to the invention, showing the locking member and first control means; Figure 2 is a transverse cross-section through second control means for the lock of Figure 1; Figure 3 is a view in the direction of arrow III of Figure 2; and Figure 4 is a view in the direction of arrow IV of Figure 2.

The part of the lock shown in Figure 1 comprises a generally rectangular housing 10 which can be secured in the edge of a door frame in a conventional manner. The lock has a locking member 11, rigidly secured to a carrier plate 12.

The carrier plate 12 is slidably mounted for movement in the direction of arrows A of Figure 1 so that the locking member 11 can be moved between a locking position, in which it projects from the housing as shown in Figure 1, and an unlocking position in which the member 11 is retracted into the housing.

The locking member 11 can be held in each of its two positions by means of a single tumbler lever 13 which is pivotally mounted on the housing at 14. The tumbler has a downwardly projecting detent 1 5 which lies on one side of a lug 16 on the carrier plate when the catch member is in the locking position, and lies on the other side of the lug 1 6 when the locking member is in its other position. The tumbler thus prevents the locking member 11 from being moved from one position to the other as a result of pressure on the locking member alone.

The underside of the tumbler 13 is curved at 17 and adjacent this portion the carrier plate 12 is cut away to provide a recess 18.

In use a cylinder lock mechanism (not shown) is mounted in a slot 19 in the housing 10 and the cam member of the locking mechanism can be rotated in each of two opposite directions by means of a key.

If the lock is in the locking position as shown in Figure 1 , clockwise rotation of the key causes the cam firstly to engage the curved surface 1 7, raising the tumbler against the action of a leaf return spring 20. This causes the detent 1 5 to rise clear of the lug 1 6. Further rotation of the key causes the cam to enter the recess 1 8 and move the carrier plate 1 2 to the right, as viewed in Figure 1, thus moving the locking member 11 into the unlocking position. Once the locking member 11 is in the unlocking position, further rotation of the key causes the cam to move clear of the curved surface 17, allowing the tumbler 13 to return, under the action of the spring 20, to the position shown in Figure 1.This time, however, the lug 16 lies to the right of the detent 1 5 as shown in Figure 1, so that the locking member 11 remains securely in the unlocking position until the key is used again. If the key is then turned anti clockwise, the above sequence of events is repeated in reverse, returning the entire lock to the position shown in Figure 1.

The lock shown in Figure 1 may be used as a conventional lock. If however it is desired to provide an over-ride mechanism which can be used in the event of an emergency, such as a fire, to render the lock inoperative without the need for the key, then the additional control means shown in Figures 2 to 4 may be fitted to the surface of one side of the door.

The control means comprises a box-like casting 21 to which is rigidly secured a support frame 22.

A guide bar 23 extends between the ends 24 and 25 of the frame 22 and the control member 26 is slidably mounted on the guide bar 23. The control member 26 is urged to the right as viewed in Figure 2 by a spring 27 which is compressed between the end 24 of the frame 22 and the end 28 of a bore 29 housed within the control member 26. In normal use the control member 26 is maintained in the position shown in Figure 2, against the action of the spring 27, by a glass plate 30, one edge of which engages in a slot 31 in the end 25 of frame 22, and the other opposite end of which engages in a slot 32 in the member 26.

The control member 26 also has a first projecting part in the form of a handle 33 and a second projecting part in the form of a peg 34.

The plate of glass 30, which is normally opaque and marked with some such wording as "Break glass for emergency exit" has not been shown in Figure 3 for the sake of clarity, but it will be understood that it is normally essential for the glass plate to be present for the member 26 to be maintained in the position shown in Figure 3 against the action of the spring.

In use a horizontally extending slot is cut in the side of the door to expose horizontally extending slot 35 (see Figure 1 ) in the housing 10 of the main lock assembly. The box-like section 21 is screwed to the door with the peg 34 projecting into the slot 35, in the position shown in dotted lines at 36 in Figure 1.

The carrier plate 12 has an upwardly extending arm 37 which extends into the region of the slot 35 as shown in Figure 1.

The housing 10 also contains a release member 38 mounted for sliding movement in the direction of arrows A. The release member 38 has a horizontally extending arm 39 which abuts against a tongue 40 of the tumbler 13 and the member 38 also has a downwardly extending arm 41 which extends into the region of the slot 35. The arms 37 and 41 are spaced slightly apart in the horizontal direction as shown in Figure 1.

As long as the peg 34 remains in the position shown by dotted lines in Figure 1 at 36, the lock operates normally, and the release member 38 is maintained in the position shown in Figure 1 by means of a compression spring 42. Should it be desired to unlock the door in the event of an emergency however, the plate of glass 20 can be smashed. This causes the member 26 to spring to the right as viewed in the Figures, carrying the peg 34 with it. If the member 26 shows any tendency to jam, a sharp blow can be delivered to the projecting handle 23, to move the member 26 to the right.

This movement causes the peg 34 firstly to engage the arm 41, moving the release member 38 to the right slightly. The arm 39 of the release member 38 presses against a sloping face 43 of the arm 40 of the tumbler 13, lifting the tumbler until the detent 1 5 moves clear of the lug 1 6.

Further movement of the peg 34 causes the arm 41 to engage the arm 37 and move the carrier plate 12 to the right, moving the locking member 11 into the unlocking position.

The key operated mechanism can thus be overridden in the event of an emergency. If, after the smash-glass device has been used, the control member 26 is returned to its original position, the door cannot be re-locked again, except by an authorised person having the key. This is because return of the member 26 causes the peg 34 to be returned to the position 36 shown in Figure 1, and so the release member 38 returns to the position shown in Figure 1 under the action of the spring 42. This permits the tumbler 13 to drop back again under the action of a leaf spring 20, causing the detent 15 to engage on the left-hand side of the lug 1 6, so that the locking member 11 remains in the unlocking position.

The invention is not retricted to the details of the foregoing embodiment.

Claims (9)

1. A lock comprising a housing, a locking member movable between a locking position in which the locking member protrudes from the housing and an unlocking position in which the locking member is retracted into the housing, first control means operable by an authorised person to move the locking member between the locking and unlocking positions, and second control means operable by anyone in an emergency to move the locking member from the locking position to the unlocking position.

2. A lock as claimed in claim 1, in which the first control means are operable by means of a key and the second control means comprise a small glass device.

3. A lock as claimed in claim 1 or claim 2, including a catch member which, when the locking member is in the locking position, holds the locking member in the locking position so that pressure on the locking member itself is insufficient to return it to the unlocking position, the second control means including a device which first engages the catch member to release it and then moves the locking member to the unlocking position.

4. A lock as claimed in any one of the preceding claims, in which the first and second control means are such that after the second control means has been operated to move the locking member to the unlocking position, the locking member cannot be returned to the locking position except by operation of the first control means.

5. A lock as claimed in any one of the preceding claims, in which the second control means comprises a control device which is held in an inoperative condition against a bias by a frangible member, but when the frangible member is broken the control device moves into an operative condition under the action of the bias.

6. A lock as claimed in claim 5, in which the bias comprises a spring device and the frangible member comprises a sheet of glass.

7. A lock as claimed in claim 5 or claim 6, in which a handle is provided to assist movement of the control device into the operative position after the frangible member has been broken, for example in case the control device should stick slightly.

8. A lock as claimed in any one of claims 5 to 7 when dependent directly or indirectly on claim 3.

in which the control device comprises a peg which projects into the housing, movement of the peg from the inoperative condition to the operative condition causing the peg first to disengage the catch member and then to move the locking member.

9. A lock constructed and arranged substantially as herein described, with reference to the accompanying drawings.