Background Art Conventional locks consist of a lock barrel rotatably received within a lock body.

The lock barrel is provided with spring loaded pins. The lock is operable by a key having a key blade, the profile of which co-operates with the spring loaded pins; some lock barrels include locking or side bars which are permitted to move radially inwardly when the pins are properly positioned, allowing the barrel to be rotated to the unlocked position.

These conventional locks are prone to tampering and may be"picked"with relative ease. In addition, the number of possible combinations is limited. The lock barrel is of complex construction and is therefore expensive to manufacture, repair or alter, requiring a vast number of parts to be held in stock by locksmiths.

An invention aimed at overcoming or at least substantially alleviating some or all of the above disadvantages is embodied in PCT publication No. W091/18166.

The lock barrel assembly disclosed in that publication has several disks which can be located by a track on the key to a predetermined position without rotation of the key, whereupon a locking bar can move radially from an outer, locked position, to an inner, unlocked position. In this disclosure, each disk has a projection or pin which is adapted to be received in a slot, groove, hole or the lock in a locking bar.

The lock barrel assembly in this disclosure had decided advantages over the prior art, one being that the"code"for the lock is carried by the locking bar and the key.

The invention in the PCT disclosure W091/18166 can be expressed in an embodiment in which, say, 16 disks and washers are stacked together. It has been found that, in connection with such an embodiment, there may be problems if parts

are not manufactured with micron accuracy. While the key can be manufactured accurately, it can be found that the pressed parts may be slightly distorted during the pressing. In addition, the parts may be made from rolled phosphor bronze sheet strips which may not be of the same thickness over the whole length of each strip.

Consequently, when, say, 16 disks and washers are stacked, the height of the stack may be slightly more or less than required. In this event, the projections or pins on each disk may not line up with the slots (etc.) in the locking bar in the longitudinal direction.

A further drawback may be presented if there are variations in the inside diameter in the hollow base for the lock barrel assembly. This may be exacerbated if the outside diameter of a disk has inaccuracy. The transverse lining up of the projection or pin on each disk with the slot, groove, hole or the like in the locking bar may be adversely affected in this regard.

In a first aspect, the present invention represents an improvement in the lock barrel assembly of W091/18166, the contents of which are imported herein by reference.

As indicated above, the lock barrel assembly in W091/18166 has the combination carried by the locking bar and a key. Consequently, in order to change the lock's combination, it is necessary only to change the locking bar and the key. The disks may remain unchanged. However, in presently-known lock barrel assemblies of the type referred to, it is necessary to dismantle the lock and remove the lock barrel assembly in order to access the locking bar.

The present invention, in a second aspect, is predicated on the desire to change a locking bar while the lock barrel assembly is left in situ. This obviously has significant advantages; for example, the changing of the combination may be carried out by relatively unskilled personnel, with minimum disturbance to the lock's environment, and in a far shorter period than is required for removal of the lock barrel assembly.

Disclosure of the Invention Accordingly, the present invention provides, in one aspect, a keyway profile plug for a lock barrel assembly operable by a key, the assembly being adapted to be received within and rotatable in a hollow lock body when the lock barrel assembly is an unlocked configuration, the lock barrel assembly further having a plurality of disks, each disk having an aperture for passage of the key and a key engaging means adjacent to the aperture and adapted to engage the key so that the key is capable of locating each disk at a predetermined position without rotation of the key, the lock barrel assembly further including a locking bar operatively associated with each disk and adapted to move radially from an outer position to an inner unlocked position only after each disk is located in its predetermined position by the key, each disk including a projection or pin adapted to be received in a slot, groove, hole or the like in the locking bar to enable the locking bar to move radially to the inner unlocked position whereby the lock barrel assembly is capable of rotating within the hollow lock body, characterised in that the keyway profile plug has: a longitudinal axis; a partially arcuate circumference transverse to the longitudinal access, the circumference being adapted to support the plurality of disks; and a plurality of grooves in the circumference, each groove adapted to receive spacer means.

In connection with the keyway profile plug of the invention, the hollow lock body into which the lock barrel assembly may be received may be selected from a wide range, so that the combined lock barrel assembly and hollow lock body may be used as a cylinder lock, cam lock, furniture lock or padlock, inter alia. The lock barrel assembly may fulfil a wide range of locking functions, simply by changing the selection of the hollow lock body.

The number of disks in the assembly can determine the range of possible combinations used. Preferably, the disks are identical.

The key engaging means may take any suitable form; preferably the key engaging means comprises one or more projections extending into the disk aperture.

If the disks are identical, as is preferred, it is possible to reverse these disks in appropriate situations so that the key engaging means can be on the right hand side or the left hand side. This can correspond to the preferred version of the key of the invention (refer below), which may have a right hand track and a left hand track machined accurately into it. This embodiment can ensure a smooth movement of the key into the aperture of the key profile plug.

In an especially preferred embodiment, both the locking bar and the key are cut to the same"code"supplied by computer software. However, in the interests of security, the physical correlation between the locking bar and the key should differ markedly, so that even when placed side by side there is no apparent resemblance.

This lack of physical resemblance is possible because the disks comprise transfer of scrambling means linking the locking bar and the key. As the key is inserted into the lock barrel assembly and the key arranges the disks in their predetermined positions, the disks essentially pick up the"code"from the key. The"code"is transferred unchanged into the locking bar, even though the physical configuration of the locking bar is different from that of the key.

Preferably the keyway profile plug is manufactured from brass or some other suitable alloy, although it is to be understood that the invention is not limited in this regard. The grooves may be milled in the circumference and ideally are milled at specific distances along the longitudinal axis.

The spacer means is preferably a spacer clip fastened into each groove. Between each spacer clip may be any desired combination of disk and spacer washer. A preferred combination is a disk, followed by a spacer washer and followed by a

second disk. In an especially preferred embodiment, a total of twelve disks is employed, which can result in more than 2.1 billion codes being available.

It will be appreciated by one skilled in the art that the keyway profile plug of the invention can overcome the problem of lining up the locking bar slots with the disk projections in the longitudinal direction.

It is greatly preferred that the key for use in the lock barrel assembly is designed so that when inserted in the keyway profile plug of the invention, the key forms a perfect circle of accurate dimensions with the circumference of the keyway profile plug. It will be appreciated by one skilled in the art that the disks of the lock barrel assembly may be completely supported by the circumference of the keyway profile plug and this can eliminate the possible transverse movement of the disk within the assembly.

The keyway plug of the invention has a keyway aperture which may have any desired shape. Because of the wide variety of shapes which may be chosen, the keyway profile plug of the invention can allow for thousands of different key profiles, independently of the disks in the lock barrel assembly. In effect, this can guarantee a large range of uniquely profiled keys.

The invention also provides a lock barrel assembly which incorporates the keyway profile plug of the invention.

The invention also provides in combination with the lock barrel assembly a key for operating the lock barrel assembly incorporating the keyway profile plug of the invention, the key bearing at least one longitudinal angled track cut into a curved surface, the track being adapted to receive the key engaging means of each disk.

Preferably, there are two such tracks, accurately machined into the key, one track being a right hand track and the other a left hand track.

One suitable material for the key is nickel-silver. The key may comprise a key blade which operates the locking assembly and a key head for gripping.

The angled track or tracks in the key may be formed and operate in the same way as disclosed in W091/18166, the contents of which are imported herein by reference.

When the correct key is inserted in the lock barrel assembly, the disks are rotated so that the external projections or pins align with the slots, grooves, holes or the like in the locking bar. By turning the key, the locking bar is pushed from its groove in the hollow lock body and meshes with the projections or pins. Thus the lock barrel assembly can rotate, permitting unlocking.

Because the projections or pins are meshed with the slots, grooves or holes in the locking bar, the key cannot be withdrawn from the locking bar assembly until the locking bar is returned to its groove in the hollow lock body. A spring biases the locking bar to the outer position, so that continuous turning of the key will be interrupted by the spring-loaded locking bar dropping back into the groove when the bar is aligned therewith, indicting the position at which the key can be withdrawn. As the key withdraws, it"scrambles"the disks as they step through the angles in the track or tracks.

The locking bar is preferably made as disclosed in W091/18166.

Whereas, in W091/18166, a cover plate may be included in the lock barrel assembly for each locking bar, so that the"code"of grooves, slots or holes therein cannot be observed with the aid of an endoscope, for example, the key way profile plug of the present invention provides an additional function: the"code"of slots, grooves, holes or the like in the locking bar cannot be observed with the aid of a device such as an endoscope. Consequently, there is no need to include a cover plate as described in W091/18166.

This invention provides in a second aspect an end cap for a lock barrel assembly, the assembly being operable by a first key, the cap being adapted to be released from the lock barrel assembly by use of a second key but not by the first key.

The invention also provides a lock barrel assembly including the cap of the invention and optionally incorporating the keyway profile plug of the invention.

The invention further provides the second key, optionally convertible to the first key.

In a third aspect, this invention provides a key with a movable element, the key being adapted to release the end cap of the invention from the lock barrel assembly only when the movable element is in a chosen position.

The lock barrel assembly suitable for use with the end cap of the invention may be any suitable assembly. However, preferably the assembly is of the type where the combination is carried by the first key and a locking bar, rather than by a key and the rotatable disks.

The first key for operating the assembly is preferably the type of key disclosed in W091/18166 and contains one or more angled tracks. The second key is preferably a modified version of the first key, so that the second key can not only operate the lock barrel assembly but also release the end cap from locking engagement with the lock barrel assembly. In one embodiment, the second key is made from the first key, with some of the first key cut away. In another embodiment, the second key may contain material not present in the first key. In yet another embodiment, the second key is convertible to the first key.

The end cap may engage the drum of the lock barrel assembly in any suitable way, such as by complementary screw threads, a bayonet fitting or other suitable fitting.

In a particularly preferred embodiment of the invention, the end cap is maintained in locking engagement with the lock barrel assembly by the locking bar.

The locking bar preferably extends into the end cap in order to maintain the end cap in locking engagement with the barrel assembly under normal circumstances.

When the first key is inserted in the lock barrel assembly, in the embodiment where the lock barrel assembly is that disclosed in W091/18166, the key causes the disks

to rotate around the longitudinal axis of the lock barrel assembly. This occurs when a key engaging means on each disk is gathered up by the angled track formed in the first key. When the first key is fully inserted in the lock barrel assembly, the disks have been rotated to the position where each of the pins or projections on the disks is located in a recess on the locking bar. The locking bar is then able to move radially inwardly, unlocking the lock. The end cap, however, cannot be removed because of its engagement with the first key. When the second key is inserted instead of the first key, not only does the locking bar move radially inwardly as is the case with the first key, but also the end cap is free to be rotated around the key.

Thus the end cap can be unscrewed or otherwise removed. Once the end cap has been removed, the locking bar can be extracted from the lock barrel assembly. A replacement locking bar can then be inserted and the cap replaced. Removal of the second key will scramble the disks, which will then require a new key, which coordinates with the new locking bar, in order to open the lock again.

As an optional feature, the second key may be converted from the first key. For example, the first key may have part of the shank formed by an annular or other shaped shell which can slide longitudinally between a first position in which the key takes the form of the first key and a second position in which the key takes the form of the second key.

With reference to the second aspect of this invention, the key with the movable element may be adapted to release the type of lock barrel assembly in W091/18166 or a different lock barrel assembly. The movable element is preferably a sleeve mounted on a shank of the key and movable between a first position, where the lock can be released, and a second position, where the lock cannot be released. Suitable lock constructions for this type of key will be apparent to one skilled in the art. The second key referred to above, convertible to the first key, described in connection with the first aspect of the invention, may be regarded as an example of the key with a movable element, although in the latter

case the key with the movable element may be adapted to release the lock barrel assembly rather than the end cap.

Brief Description of the Drawings The invention will now be illustrated by reference to the attached drawings, which, it is to be understood, are not limiting on the scope of the invention.

In the drawings: Figure 1 is an exploded isometric view of an embodiment of the keyway profile plug of the invention, showing partial spacer clips, disks and spacer washers; Figure 2 is a closer view of the embodiment of the keyway profile plug of Figure 1, including the spacer clip but omitting from the exploded view the disk and spacer washer; Figures 3a to 3j are cross sectional views of several key profiles which could be used for the keyway profile plug of Figures 1 and 2, with suitably modified keyways ; Figures 4a to 4f show details of embodiments of the parts in Figures 1 and 2; Figure 5 is a perspective view, partly broken away, of a lock barrel assembly of the invention, having an end cap of the invention, received within a hollow lock body; Figure 6 shows in exploded form the end cap, locking bar, lock barrel assembly and hollow lock body of Figure 5; Figure 7 shows the lock barrel assembly of Figure 5 inserted in the hollow lock body, with the end cap removed and with the locking bar partially removed; Figure 8 is the same view as Figure 5, without the hollow lock body being partly broken away;

Figure 9 shows the end cap featured in Figures 6 and 7, rotated through 180° ; Figure 10 shows an embodiment of a first key according to the third aspect of the invention; Figure 11 shows an embodiment of a second key according to the third aspect of the invention; Figure 12 is a sectional view taken along the lines 8-8 in Figure 8, showing the first key in Figure 10 inserted; Figure 13 is the same view as Figure 12, but showing the key of Figure 11 inserted; Figure 14 is the same view as Figure 13, but illustrating partial unscrewing of the end cap; Figure 15 is an end view showing the key of Figure 10 inserted, in which position the end cap cannot be unscrewed; Figure 16 is the same end view as Figure 15, except that the key of Figure 11 is shown inserted, with the end cap in the partially unscrewed position; and Figure 17 shows a second embodiment of the second key, which can be converted to the first form of key as shown in Figure 18.

Detailed Description of the Drawings Turning first to Figures 1 and 2, keyway profile plug indicated generally at 10 has a partially arcuate circumference 14. It is to be appreciated that the circumference is not complete. A plurality of grooves 16 are milled in the circumference 14 to "encircle"plug 10.

Each groove 16 is milled at spaced intervals along the length of plug 10. Each groove 16 is adapted to receive spacer clip 18. Spacer clip 18 is designed to encircle plug 10 but part only of spacer clip 18 is shown in Figures 1 and 2. Spacer

clip 18 includes convex protrusion 20 which is adapted to be received in concave recess 22 in plug 10 as well as in groove 16. Spacer clip 18 is thus maintained in a stable, non rotatable position around plug 10. One each of spacer clip 18 is received in each of grooves 16, spaced along the length of plug 10.

Between each pair of spacer clips 18 there is located a disk 24 and a washer 26.

Alternately, the disks and washers may be sandwiched by spacer clips in a different arrangement, such as two disks separated by a spacer washer between each pair of spacer clips 18. Preferably, there are six sets of disk pairs, resulting in a total of twelve disks.

Disk 24 includes key engaging means 28 and projection 30 designed to be received in a slot or groove of a locking bar (not shown).

Spacer washer 26 omits these features (key engaging means and projection).

In Figures 3a to 3j, ten different key profiles are shown. In each case, the key blade 40 has an arcuate upper portion 42. This is designed to complete the circular circumference of plug 10 when key blade 40 is inserted in keyway 32 (see Figures 1 and 2). By thus forming a generally complete circumference (omitting concave recesses 22), disks 24 and washers 26 will be well supported around plug 10.

One (or preferably, two) or more angled tracks are machined in arcuate portion 42 for operation of the lock barrel assembly.

Lower portion 44 of key blade 40 can take any desired profile which of course needs to be echoed by keyway 32. Ten such versions are shown in Figures 3a to 3j. It will be apparent to one skilled in the art that many thousands of other shapes are available. When one combines this with the large number of permutations available through interaction of the locking disks with the locking bar, it will be immediately apparent that that the keyway of the invention in the lock barrel assembly of the invention can provide an exceptional number of unique keys.

Turning now to Figures 4a to 4f, Figure 4a shows the top half of the drum 50.

Figure 4b shows a spacer clip 18. Figure 4c shows a disk 24 in the left hand configuration. Figure 4d shows a washer 26. Figure 4e shows a disk 24 in the right hand configuration (rotated through 180° compared with the disk in Figure 4c).

Figure 4f shows keyway profile plug 10.

In Figure 4a, the top half of drum 50 has stop grooves 52 for the purpose of receiving stop 54 of washer 26 (see Figure 4d) and stop 56 on disk 24 (see Figure 4c). Rotation of washer 26 is virtually prevented by groove 52. Rotation of disk 24 is limited to the width of groove 52.

As shown in the drawings in Figures 4c and 4e, disk 24 can be oriented in the assembly to form a"left hand"disk, in which key engaging means 28 is on the left hand side of disk 24. The same disk may be turned over to create a"right hand" disk, in which key engaging means 28 is on the right hand side of disk 24. Thus, the sequence in the embodiment in Figures 1 and 2 may comprise a spacer clip 18, a left hand disk 24, a spacer washer 26, a right hand disk 24 and a further spacer clip 18. In the embodiment illustrated, there is the capability of cutting angular tracks in the key (not shown), which allows angles of 45° to be employed, thus ensuring a smooth movement of the key into the aperture of the key way profile plug. If twelve disks are used in an assembly according to the invention, it is possible to obtain more than 2.1 billion codes.

Referring now to Figures 5 to 9, lock barrel assembly 110 is adapted for insertion in lock housing 112 and closed therein by end cap 114.

Lock barrel assembly 110 includes locking bar 116 which has a plurality of recesses, such as those shown at 118. Lock barrel assembly 110 also contains a plurality of rotatable disks, one of which is shown at 120.

End cap 114 contains internal screw threads 122 (refer Figure 9), adapted to mate with complementary screw threads 124 on lock barrel assembly 110. End cap 114

also contains locking groove 126, shaped to receive tongue 128 on locking bar 116.

End cap 114 also contains aperture 130 for insertion of the first or second key.

Aperture 130 includes cut-away portion 132.

First key 134 shown in Figure 10 has shank 136 which would normally have a thumb-plate (not shown) adjoining end 138. Shank 136 has an upper part 140 which is approximately semi-circular in cross section and into which is cut an angled track 142. Although not shown in Figure 10, angled track 142 may continue on the far (hidden) side of curved shank portion 140 and that part of the track may be identical to or different from the track shown at 142. Track 142 and the companion track (if present) end near point 144 so that engaging means (discussed later) on the disks will be gathered into track 142 or the companion track, if present, as key 134 is inserted in lock barrel assembly 110.

The second key 145 illustrated in Figure 11 is in this embodiment the same as the key in Figure 10, except that material has been excised to leave a depression 146 near end 138.

Referring now to Figure 12, key 134 is shown inserted in the lock of Figures 5 to 9.

Key engaging means 148 is shown engaging track 142 on key 134. Key engaging means 148 is on disk 120, which also has protrusion 150. Locking bar 116 is shown in the locked position with tongue 128 engaging a groove along the base of lock barrel assembly 110 and also groove 126 of end cap 114. When key 134 has aligned all disks 120 in the correct position, all protrusions 150 on disks 120 will be located in recesses 118 on locking bar 116 and locking bar 116 will move radially inwards, enabling tongue 128 to come out of the groove at the base of the lock barrel assembly and also out of groove 126 of end cap 114. At this stage, the lock can be released. However, end cap 114 will still be secured to lock barrel assembly 110.

This is to be compared with the position in Figures 13,14 and 16, which show key 145 inserted in the lock of Figures 5 to 9. As can be seen from each of these

Figures, key 145 has cut-away portion 146, which, when key 145 is fully inserted, is located in the region of end cap 114. Correct location of disks 120 enables locking bar 116 to move radially inwards, so that tongue 128 clears recess 126.

End cap 114 is able to be rotated freely around key 145 as shown in Figure 14. In contrast, key 134 prevents end cap 114 from rotating because cut away portion 132 of aperture 130 is designed to clear cut away portion 146 on key 145 but to be impeded by the upper part of shank 136 of key 134.

Turning now to the second embodiment of the first and second keys illustrated in Figures 17 and 18, key 150 is shown with a shank 136 having an angled track 142 and a pointed end 144. At the end of shank 136 opposite pointed end 144 is cap 152 which may be formed integrally with shank 136. Mounted on shank 136 in a slidable manner is sleeve 156 which includes thumb-plate 158.

When sleeve 156 is in the position shown in Figure 18, it fulfils the function of the first key, being able to release the lock but not end cap 114, since cut away portion 132 of aperture 130 in end cap 114 would not be able to clear part 162 of sleeve 156.

However, when sleeve 156 is moved in a direction away from pointed end 144, there is left bare on shank 136 cut away portion 146, so that the key in Figure 17 can carry out the function of the second key.

It is contemplated that the key of Figures 17 and 18 may be used to release a suitably-designed lock barrel assembly by movement of sleeve 156 to the appropriate position.

Industrial Applicability It will be readily appreciated by one skilled in the art that the keyway profile plug, end cap, lock barrel assembly and keys of the present invention have significant advantages over the prior art. The keyway profile plug enables an exceptionally large number of codes or combinations to be available to the lock barrel assembly.

Further, as a result of the present invention, it is now possible to change the combination of a lock by removing only the end cap and leaving the rest of the lock in situ. There is no need to remove the entire cylinder plug, as is the case with prior art locks. Compared with the prior art, the present invention can enable fast and inexpensive changing of combinations. Moreover, the procedure can be carried out by a person who does not need to have locksmithing skills. The cost of exchanging the locking bar in the circumstances is substantially less than in the case of prior art procedures.

Other modifications to the invention in its various forms are possible without departing from the spirit and scope of the invention.