GB2425325A

GB2425325A - Lock assembly with guard

Info

Publication number: GB2425325A
Application number: GB0508074A
Authority: GB
Inventors: Michael Arthur Simpson
Original assignee: Surelock McGill Ltd
Current assignee: Surelock McGill Ltd
Priority date: 2005-04-21
Filing date: 2005-04-21
Publication date: 2006-10-25
Anticipated expiration: 2025-04-21
Also published as: GB2425325B; GB2462229B; GB0919283D0; GB2462229A; GB0508074D0

Abstract

A lock assembly 30 comprising a lock body 10, a key cylinder (20, figure 1) mounted with an aperture in the front face of the lock body and a cylinder guard 32 encircling the key cylinder. The guard housing may comprise a front layer of a first material and a back layer formed from a different second material. The first material is preferably harder than the second material, for example work hardened steel and non work hardened steel. There may also be a rotable slotted disk 62 between the key cylinder and the guard housing, the disk having an aperture (slot) to allow the blade of a key to be inserted into the cylinder. The guard housing may have bevelled side walls (see Figure 4).

Description

LOCK ASSEMBLY

The present invention relates to a lock assembly having a cylinder guard, and in particular to such a lock assembly comprising a lock body having a front face which is exposed in use, the lock body being adapted for the mounting of a key cylinder in the front face.

In figure 1 there is illustrated a prior art high

security lock assembly. The assembly includes a substantial lock body 10 cast from steel and having a front face 12.

The illustrated prior art lock is adapted for mounting at the surface of a security door or other construction such that flange 14 lies against the exterior door surface and a rear portion 16 of the body is located within a recess.

Within the front face 12 of the body is mounted a handle 18. Manipulation of the handle might operate a bolting mechanism or similar located within or on the other side of the door from the lock assembly 10. A key cylinder is also mounted in the front face of the assembly.

Insertion of a key into a barrel 22 of the cylinder 20 allows the barrel 22 to rotate, operating a mechanism within the lock body 10 to lock or unlock movement of the handle 18 or its coupling to the bolting mechanism.

A variation of the lock assembly shown in figure 1 is illustrated in cross section in figure 2. In this variation the lock body 10 is mounted flush with the surface of a door, rather than being recessed. The key cylinder 20 is again mounted in the front face 12 of the lock body, and protrudes somewhat out of it. With some cylinder variants the key cylinder may not protrude, but be flush with the front face 12. Behind the key cylinder 20, mounted within the lock body, are a number of components which form a locking mechanism 24 through which the key cylinder 20 is used to lock and unlock the handle 18.

It is desirable to be able to replace the key cylinder from time to time, for example for security purposes, and to this end the illustrated assembly allows the key cylinder to be removed forwards out of the lock, by undoing machine screws which are accessible once the assembly has been removed from the door and a plate covering the lock mechanism 24 at the rear has also been removed. Removal of the cylinder in the opposite direction is undesirable as reinstalling the original or a new cylinder would require greater skill to reposition and secure.

It would also be desirable to provide physical protection to prevent malicious damage to the key cylinder, for example during an attempt to breach the door. Such attacks could be by means of a vertical blow by an axe or similar tool, an attack to the front of the cylinder by a drill or punch, or by using a firearm. Cylinder guards are well known in the prior art, for example in GB 2399595, GB 2364740 and GB 632768, but such cylinder guards are neither suited for use with surface mounted or surface recessed lock assemblies such as those discussed above, nor provide the degree of protection required for a high security application.

The present invention seeks to address the above and other problems of the related prior a.rt.

Accordingly the invention provides a lock assembly comprising: a lock body having a front face; a key cylinder mounted within an aperture in the front face of the lock body; and a cylinder guard encircling at least a front portion of the key cylinder, and also mounted within an aperture in the front face of the lock body. The apertures in which the key cylinder and cylinder guard are mounted may be the same aperture, but could be different or linked apertures, for example being concentric and possibly also coaxial.

The front face is preferably exposed when in use, for example when the lock is mounted on a door. The front face of the lock body is preferably planar, or approximately so, and a handle may also be mounted in the front face, with operation of the key cylinder serving to selectively restrict the movement or effectiveness of the handle, for example in operating a bolting mechanism.

The cylinder guard preferably comprises an annular outer sleeve, which may be bevelled to present a face having an obtuse angle adjacent to the front face of the lock body.

The cylinder guard preferably comprises a guard housing which is encircled by the outer sleeve, if provided, and which partially covers the front of the key cylinder. The guard housing is preferably formed from two layers, which may be welded together: a front layer of a harder or work hardening material; and a back layer formed of a softer or more workable material in which it is easier to form features to enable attachment to the lock body, for example by drilling and tapping bores to accept machine screws or similar fixings.

The lock assembly is preferably configured such that at least part of the cylinder guard, for example the guard housing discussed above, can be removed forwards out of the lock body, exposing the key cylinder, and such that the key cylinder can also be removed forwards out of the lock body, for example for replacement. In this way, removal and replacement of the cylinder is made easier.

The invention also provides a cylinder guard for protecting a key cylinder, having properties discussed above, for example comprising a front layer formed of a first material and being adapted to at least partially cover the front of the key cylinder, and a back layer formed of a second material different to the first material.

Embodiments of the invention will now be described, by way of example only, and with reference to the drawings of which: Figure 1 is a perspective view of a prior art surface mounted lock assembly; Figure 2 is a sectional view of a lock assembly similar to that shown in figure 1.

Figure 3 is a perspective view of a lock assembly embodying the invention; Figure 4 illustrates, in partial cross section, the assembly of figure 3 (stippled) mounted on a door; Figure 5 shows the assembly of figure 3 in cross section; and Figure 6 shows details of the cylinder guard housing component in cross section.

Referring now to figure 3 there is shown in perspective view a lock assembly 30 embodying the invention. The lock assembly is similar to that shown in figure 1, and like parts are indicated using the same reference numerals, including a lock body 10 having a front face 12, a flange 14 to abut a door or similar and a rear portion 16 for locating within a door recess. There is also a handle 18 mounted in the front face 12, but the key cylinder is hidden from view by a cylinder guard 32.

The lock assembly is shown in use in the partial section view of figure 4. The assembly 30 is mounted in a recess formed in one face of a door 40. On the other side of the door 40 is mounted a bolting mechanism 42 driving three bolts 44 for securing the door within a frame. The bolting mechanism 42 may be driven either by the handle 18 of the locking assembly or by a corresponding handle 46 of the bolting mechanism 42.

Figure 5 shows the lock body 10 in cross section, with the cylinder guard 32 fitted, but for clarity omitting the key cylinder, handle, and the lock mechanism 24 which would couple the key cylinder to the handle as described above in connection with figure 2. The cylinder guard as shown comprises four components mounted within a guard recess 50 in the front face 12 of the lock body. The side wall or walls of the guard recess are substantially perpendicular to the front face 12 such that the cylinder guard can be fitted to the lock body from the front.

The four components of the cylinder guard are an annular outer sleeve 52, a guard housing 54, a spacer 56 and a rotatable slotted disk 62. The outer sleeve encircles both the guard housing 54, and the spacer 56 which sits between the guard housing and the back of the guard recess 50. The outer sleeve is bevelled to form a conical outer face which makes an obtuse angle with the front face of the lock body, and is attached to the lock body by a welded joint 58 where the two faces meet.

The guard housing 54 encircles a front portion of the key cylinder, extending further from the front face of the lock body than the outer sleeve. The guard housing also has a conical outer face which is continuous or nearly continuous with the conical face of the outer sleeve 52.

Inward of the conical face the guard housing also has a front portion which partially covers the front of the key cylinder, but in which a key aperture 60 is formed, to allow the insertion of a key into the barrel of the key cylinder.

In the arrangement of figure 5 this key aperture has a conical inner face which narrows towards the key cylinder.

The slotted disk 62 which has a slot to allow the blade of a key to be passed through and into the key cylinder, is located immediately behind the key aperture 60, and is unattached to the guard housing so as to rotate freely in a circular aperture. The slotted disk is preferably made of a work hardening steel such as manganese steel, and is effective at thwarting attempts to drill or punch the key cylinder.

The guard housing is secured to the lock body by three machine screws 64 spaced around the perimeter of the guard housing and passing through suitable apertures in the spacer 56. Only one of these screws is shown in figure 5. The abutting walls of the guard housing 54 and the outer sleeve 52 are substantially cylindrical or non tapering, and therefore perpendicular to the front face 12 of the lock body. This allows the guard housing 54 to be removed from the lock body 10 to reveal the key cylinder by undoing the machine screws 64. The key cylinder may then be released from the lock body and also removed forwards through the front face of the lock body, for example to be replaced by another key cylinder.

The guard housing 54 is shown in more detail in the cross section of figure 6. To increase the resistance to attack it is preferable to form the guard housing from a particularly strong or hard steel, such as a work hardening steel, of which manganese steels are particular examples.

Although such steels can be cast and ground, they are very difficult to machine and drill. The guard housing 54 is therefore formed of a front layer 70 cast and ground from a work hardening steel, which is welded to a rear layer 72 of a different steel in which tapped apertures to accept the machine screws 64, or indeed any other configuration for attaching the housing to the lock body, may be formed more easily. A suitable weld line for joining the front and rear layers is shown as 76.

The described embodiments may be changed in a variety of ways without departing from the scope of the invention.

For example, the lock body may be entirely surface mounted or entirely recessed. The key cylinder may extend beyond the front face of the lock body, extend to the front face or not protrude beyond the front face at all. The front face of the lock body will typically be planar, but could be curved or facetted in various ways, for example in order to deflect attacking blows.

The lock assembly has been particularly described in connection with a door and associated bolting mechanism, but could be used in a variety of other applications and orientations. The slotted rotatable disk defending the key cylinder barrel could be omitted, for example if an armoured key cylinder is to be used.

The lock assembly may be supplied in component form, or may be supplied without including a key cylinder, for example to allow an end user or fitter to install their own selected key cylinder on site.

The lcck mechanism 24 coupling the key cylinder 20 to the handle 18 or other facility to be selectively locked has not been described in detail but could, for example, comprise a rotatable cam driven by the key cylinder and bearing upon a sliding plate driven to move between positions where the handle or other facility is respectively locked and unlocked.

The lock body could be provided with a decorative and/or protective separate front face component permanently or removably secured to the rest of the lock body.

Claims

CLAIMS: 1. A lock assembly comprising: a lock body having a front face; a

key cylinder mounted within an aperture in the front face of the lock body; and a cylinder guard encircling the key cylinder and also mounted within an aperture in the front face of the lock body.
2. The lock assembly of claim 1 adapted to accept insertion and removal of the key cylinder from the front of the lock body.
3. The lock assembly of claim 1 or 2 wherein the cylinder guard comprises a guard housing encircling said key cylinder and at least partially covering the front of said key cylinder.
4. The lock assembly of claim 3 wherein said guard housing comprises a front layer formed of a first material, the front layer at least partially covering the front of said key cylinder, and a back layer formed of a second material different to said first material.
5. The lock assembly of claim 4 wherein said first material is harder than the second material.
6. The lock assembly of cLaim 4 wherein said first material is a work hardening steel and said second material is not a work hardening steel.

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7. The lock assembly of claim 4, 5 or 6 wherein said back layer has defined therein one or more apertures adapted to accept fixings to secure the guard housing to the lock body.
8. The lock assembly of any of claims 3 to 7 further comprising a disk rotatably retained inbetween the key cylinder and the guard housing, the disk having an aperture therein to allow the blade of a key to be inserted into the key cylinder.
9. The lock assembly of claim 8 wherein said disk is formed of a work hardening steel such as a manganese steel.
10. The lock assembly of any preceding claim wherein the cylinder guard extends beyond the front face of the lock body.
11. The lock assembly of claim 10 wherein the aperture in the front face of the lock body within which the cylinder guard is mounted is a guard recess which encircles the key cylinder.
12. The lock assembly of claim 10 or 11 wherein said guard recess is partly defined by an outer side wall adjacent to said front face of the lock body, the outer side wall being substantially perpendicular to the front face such that the cylinder guard can be inserted into the guard recess from the front.
13. The lock assembly of any of claims 3 to 12 wherein the cylinder guard further comprises a sleeve encircling said - 11 - guard housing and having a bevelled side wall making an obtuse angle with the front face of the lock body.
14. The lock assembly of claim 13 wherein the front portion of the guard housing also has a bevelled side wall substantially continuous with the bevelled side wall of the sleeve.
15. The lock assembly of claim 13 or 14 wherein the sleeve is welded to the lock body, and is not fixed to the guard housing.
16. The lock assembly of any preceding claim further comprising a handle moveable relative to the lock body, use of the handle being selectively restricted by operation of the key cylinder.
17. The lock assembly of claim 16 wherein the handle is rotatably mounted in the front face of the lock body.
18. A leaf moveable within a frame comprising a bolting mechanism operably coupled to a lock assembly of any of claims 1 to 17.
19. A cylinder guard for protecting a key cylinder, the guard comprising a front layer formed of a first material, the front layer being adapted to at least partially cover the front of the key cylinder, and a back layer formed of a second material different to the first material.
20. The cylinder guard of claim 19 wherein the first material is harder than the second material.

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21. The cylinder guard of claim 19 or 20 wherein the first material is a work hardening steel, such as a manganese steel.
22. The cylinder guard of claim 21 wherein the back layer comprises features adapted to permit the cylinder guard to be fixed relative to the key cylinder.
23. The cylinder guard of claim 22 wherein the features are tapped bores or apertures.
24. The cylinder guard of any of claims 19 to 23 further comprising an annular outer sleeve encircling both the front layer and the back layer.
25. A lock mechanism comprising the cylinder guard of any of claims 19 to 24.