GB2512579A

GB2512579A - A lock guard

Info

Publication number: GB2512579A
Application number: GB1304268.4A
Authority: GB
Inventors: Christopher Eric Belcher
Original assignee: UAP Ltd
Current assignee: UAP Ltd
Priority date: 2013-03-08
Filing date: 2013-03-08
Publication date: 2014-10-08
Anticipated expiration: 2033-03-08
Also published as: GB2512579B; GB201304268D0

Abstract

A cylinder lock guard for a euro-style cylinder lock comprises first and second guards 2, 3 surround each end of the cylinder and clamp around an associate lock casing (5, fig.2). The two guard parts are inter-connected such that they are unable to rotate relative to one another, e.g. one the parts may define a projecting peg 12 that locates in a mortised slot 13 in the other part. At least one of the parts defines a planar surface 14 that is covered by a drill-proof plate 15 of perhaps hardened steel. The guard parts 2, 3, may be smoothly curved to prevent gripping by a tool such as pliers.

Description

A LOCK GUARD

The present invention relates to a guard for a euro-style cylinder lock having a lock cylinder and an associated lock casing.

Euro-style cylinder locks are prone to attack by criminals seeking to force entry to a property. In such an attack the lock cylinders of such locks are targeted as they can be snapped and the snapped off part removed to gain access to the door locking mechanism in the lock casing. The lock cylinder is usually snapped by gripping the projecting cylinder of the lock on one side of a door or window with a tool or by drilling into the lock cylinder so that a lever can be inserted to snap it. Other forms of attack include drilling into the body of the lock cylinder and lock casing, again with a view to accessing the locking mechanism.

The object of the present invention is to provide a guard for a euro-style cylinder lock that inhibits both snapping of the lock cylinder close to a lock casing and drilling into the body of the lock casing.

According to the present invention there is provided a guard for a euro-style cylinder lock having a lock cylinder and an associated lock casing, the guard comprising first and second parts that are adapted to fit respectively around each end of the lock cylinder on opposite sides of the lock casing and to be connected together such that they clamp around the lock casing, the two parts inter-connecting such that they are unable to rotate relative to one another and at least one the parts defining a planar surface covered by a drill-proof plate that, in use, is adapted to lie in contact with an adjacent surface of the lock casing.

Preferably, one of the parts defines a projecting peg that locates in a complementarily shaped mortise in the other part, the profile of the peg being such that it cannot be rotated relative to the mortise.

Preferably also, the first and second parts are connected together by a bolt that is screwed into a tapped blind bore through an external aperture formed in one of the parts. Preferably, said external aperture is defined by that part of the guard adapted to be located on the internal side of the lock.

Preferably also, the bolt locates through a spring washer which, in use, is clamped between a head of the bolt and an external surface of said one part.

Preferably also, at least one of the parts is adapted to be secured to the cylinder by at least one fixing. Advantageously, said one part is adapted to be secured to opposite sides of the cylinder by grub or set screws.

Preferably also, external surfaces of the first and second parts are profiled to inhibit gripping of the part by pliers or a similar tool.

All of the foregoing features are provided with the intention of protecting a euro-style cylinder lock to which the guard is fitted from a successful attack designed to break or force the lock. Preferred additional features of the invention are described in the dependent claims appended hereto.

An example of the present invention will now be described with reference to the accompanying drawings, in which:-Fig. 1 is a perspective view of a guard for a euro-style cylinder lock in accordance with the present invention; Fig. 2 is a perspective view of the guard shown in Fig. i but to a reduced scale and when in use attached to a lock cylinder and an associated lock casing; Fig. 3 is a side view of the guard shown in Fig. 1; Fig. 4 is an exploded perspective view of the guard shown in Fig. i; and Fig. 5 is a perspective view of a longitudinal cross-section of the guard shown in Fig. 1.

As shown in the drawings, a guard 1 for a euro-style cylinder lock, such as is shown in combination with the guard 1 in Fig. 2, comprises first and second parts 2 and 3 that are adapted to fit respectively around each end of a lock cylinder 4 on opposite sides of a lock casing j of the lock and that connect together such that they clamp around the lock casing 5. in this way, the guard 1 acts to inhibit breakage of the lock cylinder 4 close to the lock casing 5 by covering and supporting it. The guard 1 may be factory-fitted and supplied along with lock cylinders 4 and lock casings 5 for installation in a door at the same time as the lock is fitted but may also be supplied separately for retro-fitting to an existing lock.

As can be seen in the drawings, the two parts 2, 3 of the guard 1 comprise solid components that are preferably die cast from steel or zinc-based alloys that include aluminium, magnesium and copper (commonly called Zamak' or Zamac' alloys). These materials retain their strength and hardness over time to resist attack and thereby protect the lock cylinder 4.

The two parts 2, 3 each comprise an elongated portion 6 that defines an aperture 7 of complementary shape to the outer profile of the lock cylinder 4 and through which the appropriate end of lock cylinder 4 is fitted.

The end of the lock cylinder 4 projects from a front surface 8 of the portion 6, the front surface 8 being exposed, in use, on one or other side of a door.

However, side surfaces 9 of the parts 2, 3 of the guard 1 together with a bridging portion 10 defined by the part 2 are adapted to be covered and therefore hidden, in use, within the body of a door. To inhibit gripping of the exposed surfaces 8 of the guard 1 by tools such as pliers or similar, these

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surfaces are profiled by being smoothly sculpted using curving surfaces that extend in all directions. These surfaces also inhibit drilling into the lock as they prevent a drill bit from gaining a purchase. The projecting end of the lock cylinder 4 is vulnerable to attack but typically this is provided with an area of weakness (see the slot marked Win Fig. 2) close to the front surface 8 of the guard 1 so that it will snap at this point and not at a more vulnerable point within the guard i. Snapping of the lock cylinder 4 at such a point along its length does not provide access to the lock casing 5.

The two parts 2, 3 of the guard 1 are linked by the bridging portion 10 that projects from the part 2 so that in use it extends beneath the lock casing and provides a flat upper surface U on which the lock casing rests. At the end of the portion 10 is a projecting peg 12 that locates in a complementarily shaped mortise 13 in the part 3. The profile of the peg 12 is designed so that it cannot be rotated relative to the mortise 13. Preferably, therefore the peg 12 has an angular profile and in the illustrated embodiment has a rectangular profile but it will be appreciated that other non-rotatable profiles could he used. Prevention of rotation between the parts 2 and 3 is important as, in use, it prevents one end of the lock cylinder 4 from being twisted or rotated relative to the lock casing with the intention of snapping the cylinder 4.

In the illustrated embodiment, the bridging portion 10 is provided on the part 2 that is intended to be located on an exterior side of a door, which is the side that will be typically attacked in an attempt to force the lock.

However, in other embodiments of guard, the bridging portion could be provided on the part of the guard intended to be located on an interior side of a door. In some embodiments, the lower surface of the bridging portion 10 may be formed with a channel to accommodate a bar or bolt linking door handles.

On the opposite sides of the elongated portions 6 to the exposed surfaces 8 are planer inner surfaces 14 between which the lock casing is located. In use, the surface 14 on the interior part 3 of the guard abuts the lock casing 5 but on the exterior side of the guard 1 a drill-proof plate 15 is provided that is interposed between the surface 14 of the part 2 and the lock casing 5. In other embodiments of guard, a second drill-proof plate may be interposed between the surface 14 of the part 3 and the lock casing 5 in addition to that covering the surface of the part 2. The drill-proof plate 15 is preferably made of hardened steel and has an exterior edge 16 that is profiled to match that of the surface 14 and an aperture 17 identical is size and shape to the aperture 7 so that the plate 15 fits exactly between the portion 6 and the lock casing, as shown in Fig. 1. The plate 15 is provided to inhibit drilling through the guard 1 into the lock casing and in addition will blunt any drill bit that comes into contact with it. As, in use, the plate i is clamped between the inner surface 14 of the part 2 and the side of the lock casing 5 and is also retained in this position by the lock cylinder 4, it does not need to be attached to the part 2. However, to keep it iii position prior to fitinent of the guard 1, it may be secured to the surface 14 by a layer of sticky tape, an adhesive or similar.

The two parts 2, 3 are connected through the bridging portion io by a bolt 18 that is screwed into a tapped blind bore 19 through an external aperture 20 formed in the part 3. In use, the bolt i8 is not, therefore, visible from the exterior of the guard 1 on the exterior side of the door 1 so that it cannot be removed by unscrewing. The head of the bolt 18 is preferably provided with a security socket 21 so that only special driving tools can be used to screw and unscrew the bolt iS into and out of the bore 19. In addition, the tip 22 of the bolt 18 opposite its head is preferably tapered, advantageously to a point. This is an additional security measure intended to inhibit and deflect a drill bit if an attempt is made to drill out the bolt iS from the exterior side of the door. As a further security measure, a spring lock washer 23 is located between the head of the bolt i8 and the rim of the aperture 20. The washer 23 exerts a spring force between the head of the bolt i8 and the part 3 that maintains the washer 23 hard against the part 3 and the bolt thread hard against the threaded bore thereby creating friction and resistance to rotation.

In addition to the foregoing, the part 2 is preferably secured to the lock cylinder 4 by at least one fixing 24, which advantageously comprises a grub or set screw. Preferably, a pair of grub or set screws 24 is used and these are screwed through threaded bores 25 formed through opposing side surfaces 9 of the part 2 against the surface of the lock cylinder 4. The screws 24 prevent the lock cylinder 4 from being moved relative to the part 2 by exerting a compressional or clamping force on the lock cylinder 4 through the bores 25. As with the bolt iS, the screws 24 are preferably adapted to he driven by a security screw driver, for example by being provided with a star-shaped screw-drive socket 26.

Hence, it will be appreciated that in use the guardi acts to that inhibit both snapping of the casing of the lock cylinder 4 and drilling into the body of the lock casing 5, in particular by inhibiting rotation of the lock cylinder 4 and by inhibiting drilling into the body of the lock casing 5. In the event that the lock cylinder 4 does snap, the screws 24 inhibit withdrawal of the broken portion of the cylinder 4 from the guard t and thereby prevent access to the lock casing 5.

Claims

CLAIMS1. A guard for a euro-style cylinder lock having a lock cylinder and an associated lock casing, the guard comprising first and second parts that are adapted to fit respectively around each end of the lock cylinder on opposite sides of the lock casing and to be connected together such that they clamp around the lock casing, the two parts inter-connecting such that they are unable to rotate relative to one another and at least one the parts defining a planar surface covered by a drill-proof plate that, in use, is adapted to lie in contact with an adjacent surface of the lock casing.
2. A guard as claimed in Claim 1, wherein the said part defining the planar surface covered by the drill-proof plate is the part of the guard adapted to be located on an external side of the lock.
3. A guard as claimed in Claim 1 or Claim 2, wherein the drill-proof plate is comprised of hardened steel.
4. A guard as claimed in any of Claims 1 to 3, wherein one of the parts defines a projecting peg that locates in a complementarily shaped mortise in the other part, the profile of the peg being such that it cannot be rotated relative to the mortise.
5. A guard as claimed in Claim 4, wherein the peg has an angular profile.
6. A guard as claimed in any of Claims I to 5, wherein the first and second parts are connected together by a bolt that is screwed into a tapped blind bore through an external aperture formed in one of the parts. -p -
7. A guard as claimed in Claim 6, wherein said external aperture is defined by that part of the guard adapted to be located on the internal side of the lock.
8. A guard as claimed in Claim 6 or Claim 7 wherein the tip of the bolt opposite its head is tapered to a point.
9. A guard as claimed in any of Claims 6 to 8, wherein the bolt locates through a spring washer which, in use, is clamped between a head of the bolt and an external surface of said one part.
10. A guard as claimed in any of Claims 1 to 9, wherein at least one of the parts is adapted to be secured to the lock cylinder by at least one fixing.
ii. A guard as claimed in Claim 10, wherein said one part is adapted to be secured to opposite sides of the lock cylinder by grub or set screws.
12. A guard as claimed in Claim 10 or Claim ii, wherein said one part that is adapted to be secured to the lock cylinder is that part of the guard adapted to he located on the external side of the lock.
13. A guard as claimed in any of Claims 1 to 12, wherein external surfaces of the first and second parts are profiled to inhibit gripping of the part by pliers or a similar tool.
14. A guard as claimed in Claim 13, wherein external surfaces of the first and second parts are profiled by being smoothly sculpted using curving surfaces that extend in all directions.
15. A guard for a euro-style cylinder lock substantially as described herein with reference to the accompanying drawings.