GB2549193A

GB2549193A - A lock

Info

Publication number: GB2549193A
Application number: GB1703916.5A
Authority: GB
Inventors: Southall Ian; Chantler Roger; Jennings David; Mcloughlin John
Original assignee: K I J SECURITY LOCKS Ltd
Current assignee: K I J SECURITY LOCKS Ltd
Priority date: 2016-03-11
Filing date: 2017-03-10
Publication date: 2017-10-11
Anticipated expiration: 2037-03-10
Also published as: GB201604177D0; GB2549193B; GB201703916D0

Abstract

A lock for a door or other closure comprises a cylinder 3, a cam, and a drive bar element. When an attempt is made to vandalise the lock by breaking off the outside cylinder 3 at point 19 (see figure 4), the cam and the drive bar element are axially retractable towards the inside cylinder 2. This is preferably via biasing spring 10 and security pins 12 biased by spring 11. The drive bar element may comprise a profiled free end 17 adapted to hinder grip by a tool (19, fig. 5) after the cylinder has been broken away. This end may be in the shape of a smooth dome, a bullet nose, or a conical or convex shape. The axial movements of the drive bar element and the cam may occur independently or together. The axial movement may be limited by abutment between a peripheral flange 16 on the cam and a groove 15, 15 in the cylinder wall. The lock may be a double cylinder euro profile lock.

Description

A LOCK

The present invention relates to a lock, and particularly to a lock for mounting on a closure and for operating a locking mechanism of the closure. Such a lock is that often known as a Euro Cylinder or Euro profile cylinder lock.

Such Euro Cylinder locks usually have a cylinder in which a rotatable barrel is mounted and which can be turned to and from an open, unlocked, and closed, locked position by a key which operates key pins to move spring-loaded driver pins to a shear line defining a boundary between the barrel and cylinder so that the barrel can be rotated on turning the key. There is also a cam secured to the barrel having a part which operates the locking mechanism of the closure. When the barrel rotates, so does the cam so that the cam part operates the locking mechanism. However, the Euro Cylinder lock has an inherent weak point, namely at a cut out seating area near the centre of the cylinder in which the cam is seated. If the lock is vandalised in the locked position by snapping off or bending a part of the cylinder which is at or on an external or exterior face of the closure owing to this weak point, the locking mechanism can be operable to unlock the closure, so a perpetrator can gain unlawful entry to a property on which the closure is mounted.

It is an object of the invention to obviate or substantially mitigate this disadvantage.

According to the present invention there is provided a lock, comprising a cylinder, a cam, and a drive bar element, the cam and drive bar element being axially retractable into the cylinder when an attempt is made to vandalise the lock.

Using the invention, it is possible to prevent operation of an opening and closing mechanism for a closure, such mechanism for example comprising a latch or bolt normally operated by the cam. The drive bar element may have a profiled free end. This free end may be tapered in a direction away from the body of the lock, and may be of any suitable configuration, such as domed, convex, bullet-nosed or conical.

The cam and drive bar element may be axially retractable independently of each other, or together, the axially retractable feature being a built-in design feature of the lock.

It will be understood that the invention extends to a closure such as a door or window in combination with a lock according to the invention.

An example of a lock according to the invention is hereinafter described in the accompanying drawings.

Fig.i is an exploded schematic perspective view of a Euro cylinder profile lock embodying the invention;

Figs lA, lB and lC show schematically the lock of Fig.i when part has been broken away;

Figs 2, 3 and 4 show schematically, to a larger scale than the previous Figures, operative modes of the lock of Fig 1;

Fig.5 shows schematically part of an operation to operate the lock after vandalisation; and

Fig. 6 shows schematically a further part of an operation to operate the lock after vandalisation.

Referring to the drawings there is shown a lock 1, comprising in this embodiment two axially aligned cylinders 2, 3, a cam 4, and a drive bar element 5, the cam 4 and drive bar element 5 being axially retractable into the cylinder 3 when an attempt is made to vandalise the lock 1.

The cam 4 has an integral projection 6 which in use operates the opening and closing mechanism of a closure, the cam 4 being mounted in a space between the cylinders 2 and 3. Inside each cylinder 2, 3 is a barrel 7 which seats the drive bar element 5, which carries an elongate member 8 mounted for reciprocation in a slot or keyway 9 in the barrel 7, there being biasing means in the form in the embodiment of a coil spring 10 abutting the inward end (left hand as viewed in Figs.2-6) of the drive bar element 5.

The drive bar element 5 mounts under pressure of biasing means in the form of a spring 11 opposed security pins 12. The cylinder 2 also has a circumferential groove 13 of channel shape 14, the facing walls of which form abutments 15,15’ against which a stop 16 in the form of a peripheral flange of the cam abuts, the space between the abutments 15,15’ determining the axial movement of the cam 4.

The forward end (to the right as viewed in Figs 2 to 6) of the drive bar element 5 is profiled to provide a smooth forwardly facing bullet-nose end surface 17. This forward end is preferably tapered in a direction away from the body of the lock and may be of any suitable configuration, such as domed, convex, bullet-nosed or conical.

Referring to Figs. 2 and 3 the lock 1 is mounted through the thickness of a closure ( not shown) with the cylinder 2 being on the inner face of the closure, i.e. on the room side of the closure when the closure is a door mounted for opening and closing in a doorway. The cylinder 3 is then on the outside, i.e. on the outer face of the closure. Both cylinders are operated by a customised key 18 as shown, though the cylinder 2 could instead be operated by a turn or thumb-screw arrangement.

As will be known, the lock 1 is operated as mentioned by the customised key 18 which on insertion in a key-hole in a plug of the respective cylinders 2,3 part 5 aligns key pins and spring-loaded driver pins along a shear line between the plug and the respective cylinder 2,3 so that the plug and thus the cam 4 can be rotated by the key to open (unlock) or lock the closure , the part 6 of the cam 4 engaging cooperating parts of the locking mechanism for locking and unlocking the closure. The cam 4 and a seating for it between the cylinders 2, 3 are it will be understood essentially situated internally of the closure with the locking mechanism. Fig. 2 shows operation of the lock 1 from the room side of the door while Fig.3 shows operation from the outside of the room. These are the normal operating modes of the lock 1.

Fig. 4 shows the case when an attempt is being made to gain unlawful entry to the (locked) room by breaking the outer cylinder 3 off the lock, as shown by the arrow ‘X’. The lock 1 has a groove 19 which eases the breaking of the cylinder 3 from the rest of the lock 1 in a sacrificial manner so that the cylinder 2 and cam 4 remain undamaged. In the Fig. 4 mode, the spring 10 pushes the drive bar element 5 forwards, to the right as viewed, and the cam 4 is in turn pushed to the right, both actions being more or less instantaneous on forced removal of the cylinder 3.The distance moved by the cam 4 is controlled by the wall 15’ against which the cam 4 abuts. In turn, the distance the drive bar element 5 moves forward is controlled by how far the cam 4 moves forward. The pins 12 deploy under the action of spring 11 to control axial movement of the drive bar element 5 which in turn stops the drive bar element from being forced too far to the left, see below, and so the element 8 and keyway 9 are not disengaged and can thereby stop rotation of the cam 4.

It will be appreciated that in the vandalised mode shown in Fig. 4, the right hand end, as viewed, of the cam 4 and of the drive bar element 5 are exposed. The burglar would then try to operate the cam to unlock the door by using a tool 19 such as a mole wrench or pliers to grip the drive bar element 5 to extract it. However, the smooth profiled surface 17 of the drive bar element 5 prevents purchase on the drive bar element by the tool 19, which slips off. At the same time, pressure from the tool in the direction of the cylinder 2 to try to achieve any purchase on the drive bar element 5 has the effect of pushing the drive bar element 5 axially to the left against the pressure of the spring 10, so reducing the area of the drive bar element which can be attempted to be gripped and protecting the lock against unlocking. It is the effect of the built-in backward axial movement and the profiled surface 17 of the drive bar element 5 which protects the closure from unlocking. Moreover, the cam 4 is prevented from rotation, and an attempt to grip it by a tool in the Fig.3 mode also pushes it backwards to the left axially.

Preferably, the axial movement of the drive bar element 5 and/or the cam 4 is a distance over a range of 2mms to 4mm inclusive. Advantageously, the distance is at between 2.5 mm and 3 mm inclusive.

The lock 1 is thus protected from unlawful entry following vandalism.

Claims

1. A lock comprising a cylinder, a cam, and a drive bar element, the cam and drive bar element being axially retractable into the cylinder when an attempt is made to vandalise the lock.

2. A lock according to Claim l, wherein the drive bar element comprises a profiled free end adapted to hinder grip by a tool when an attempt is made to vandalise the lock.

3. A lock according to Claim 2, wherein the profiled free end comprises a smooth domed configuration.

4. A lock according to Claim 2, wherein the profiled free end comprises a bullet-nose configuration.

5. A lock according to Claim 2, wherein the profiled free end comprises a conical configuration.

6. A lock according to Claim 2, wherein the profiled free end comprises a convex configuration.

7. A lock according to any preceding Claim, wherein the drive bar element is axially movable independently of the cam.

8. A lock according to any of Claims 1 to 6, wherein the cam is axially movable independently of the drive bar element.

9. A lock according to any of Claims 1 to 6, wherein the drive bar element and cam are axially movable together.

10. A lock according to any one of Claims 7 to 9, wherein the axial movement is a distance over a range of 2mms to 4mm inclusive.

11. A lock according to Claim 10, wherein the distance is between 2.5 mm and 3 mm inclusive.

12. A lock according to any preceding Claim, wherein the cam and the cylinder each comprise means adapted to limit axial movement of the cam.

13. A lock according to Claim 12, wherein the limit means comprise respective abutments of the cam and cylinder.

14. A lock according to Claim 14, wherein the respective abutments comprise axially facing spaced walls of a groove in a wall of the cylinder and a peripheral flange on the cam.

15. A lock according to any preceding Claim, wherein the drive bar element is mounted under pressure of a biasing means for axial movement.

16. A lock according to any preceding claim, comprising a double cylinder Euro profile lock.