Anti-tamper lock

Abstract

 There is described a lock cylinder comprising a housing having a first section, a second section and a connecting section therebetween such that a gap is provided between the first section and the second section, at a location adjacent the connecting section. A cam is rotatably mounted on the housing, the cam being moveable to a position in which the cam is located in the gap and is contained within the profile of the housing. The housing has a longitudinal passageway extending from the first section to the second section and which passes at least partly through the gap, the passageway being configured for receiving a strengthening element therethrough and the cam is configured for lost motion so that the cam is not required to enter the gap during operation of the lock.

Description

Field of the Invention

[0001] The present invention relates to an anti-tamper lock.

Background to the Invention

[0002] It is known that traditional cylinder locks are weak in their centre (half-way between the front and rear sides of a door) because the cylinder housing in that region is significantly reduced to accommodate a rotating cam to activate the lock. As a result, it is becoming increasingly common for such locks to be broken by intruders using a small crowbar to remove the outer door furniture (e.g. escutcheons) and then rocking the cylinder back and forth to cause it to sheer along its centre. Half of the cylinder can then be extracted enabling the insertion of a tool or rod into the lock casing to lift the tumbler and withdraw the bolt.

[0003] One solution to this problem includes the use of two additional metal strengthening strips provided along either side of the depending web portion of the cylinder. In another solution a sheer point is provided in the cylinder housing so that it will preferentially break before the cam portion thereby preventing access to the latch mechanism. However, as the cam is required to pass through the cylinder in both cases, the space available for strengthening features is limited and therefore the effectiveness of each solution is hampered.

[0004] It is therefore an object of the present invention to provide a lock cylinder which addresses at least some of the above-aforementioned problems.

Statements of invention

[0005] According to a first aspect of the present invention there is provided a lock cylinder comprising:

a housing having a first section, a second section and a connecting section therebetween such that a gap is provided between the first section and the second section, at a location adjacent the connecting section; and

a cam rotatably mounted on the housing and which is moveable to a position in which the cam is located in the gap and is contained within the profile of the housing;

wherein the housing has a longitudinal passageway extending from the first section to the second section and which passes at least partly through the gap, the passageway being configured for receiving a strengthening element therethrough; and
wherein the cam is configured for lost motion so that the cam is not required to enter the gap during operation of the lock.

[0006] Embodiments of the present invention therefore provide a lock cylinder which can be retrofitted into standard lock casings since the cam can be received in the gap when the strengthening element is removed, but which can also provide additional resistance to breaking upon tampering by provision for a strengthening element to pass across the gap to thereby strengthen the weakest portion of the housing. It will be noted that the lost motion of the cam is required in order to make room for the strengthening element, which is fitted after the lock cylinder has been inserted into the lock casing.

[0007] Accordingly, embodiments of the present invention aim to prevent (or minimise the risk of) the housing being snapped and removed to allow access to the bolt mechanism. In certain embodiments, even if the housing is broken in two, the strengthening element may still be able to retain the two portions together to prevent any removal of parts of the lock which will allow the required access to the bolt. Consequently, the strengthening element may serve in one or both of a strengthening capacity and a retaining capacity.

[0008] The lock cylinder may further comprise a strengthening element.

[0009] In particular embodiments, the strengthening element may comprise one or more of a bolt, screw, rod, pin, bar, plate, cable, wire or chain.

[0010] At least a portion of the strengthening element may be threaded for engagement in a complementary portion of the passageway. In one embodiment, the portion of the passageway provided in the second (e.g. outer) section may be threaded for receipt of a correspondingly threaded end of the strengthening element.

[0011] The passageway may terminate in a blind hole (i.e. the passageway may not extend completely through one of the first or second sections). This is advantageous in that, in practice, the strengthening element can be inserted into the passageway from the inner (e.g. first) section of the housing so that any potential intruders viewing the exposed end of the outer (e.g. second) section will not know that a strengthening element is included in the lock cylinder and will not have access to the strengthening element to remove it.

[0012] The strengthening element may comprise a shaft with a head at one end thereof. The head may have an engaging part for engaging with a tool such as a screwdriver. The head may be countersunk.

[0013] In a specific embodiment, the strengthening element may comprise a rod having a cable passing longitudinally therethrough and wherein the cable has a first and a second end which serve to retain the cable in the rod. An advantage of this embodiment is that even if the housing and rod are both snapped, the cable may serve to retain the two sections of the housing together to prevent removal of the lock cylinder and access to the bolt mechanism.

[0014] The cable may be constituted by a so-called Bowden cable or a wire rope.

[0015] The cable may be located along the axis of the rod.

[0016] In other embodiments, the strengthening element may comprise two sections of rod having a connector therebetween. The connector may comprise a metal (e.g. spring steel) plate which may be secured to the two sections of rod via metal fasteners (e.g. dowels, pins or screws).

[0017] In one embodiment, the lock cylinder may further comprise at least one (e.g. two) escutcheon and the passageway (and the strengthening element) may extend through the housing and into the at least one escutcheon. In certain embodiments, the at least one escutcheon will abut a portion of a door and this will further help to prevent removal of portions of the lock due to the retention of the escutcheon by the strengthening element.

[0018] The housing may have a conventional keyhole shaped cross-section comprising a cylindrical upper portion and a depending web portion. The connecting section and the passageway may both be provided in the web portion. As with traditional cylinder locks, a transverse hole may be provided through the connecting section of the web for accommodating a transverse locking screw to retain the lock housing In position. It will be understood that the transverse hole will further weaken the connecting section and the passageway must be provided either above or below the transverse hole to allow the strengthening element to pass through the passageway without being blocked by the transverse locking screw. In traditional cylinder locks, the web portion may also house a radial pin tumbler mechanism which only permits a plug to rotate (and cause the cam to rotate also) when the correct key is inserted into the lock. Accordingly, it may be difficult to find room to accommodate the passageway and strengthening element of the present invention in such traditional locks without re-designing or altering the size of the parts concerned. However, the present invention can be advantageously included in locks configured according to the applicants earlier patent EP0892130 B1 as, in this design, the pin mechanism is contained in the cylindrical portion of the housing leaving plenty of room for the passageway and strengthening element in a conventionally-sized web portion.

[0019] In a particular embodiment, the strengthening element is retained in the lock by a cap screw. The strengthening element may be constituted by a bolt having a threadless outer surface and a threaded hole for insertion of a threaded cap screw. The bolt may comprise a shaft having a head at one end and the threaded hole provided at the other end. The threaded hole may extend axially part-way into the shaft. The cap screw may comprise a threaded shaft and an enlarged head. The shaft of the bolt may comprise a cut-out for receipt of a retaining element configured to prevent rotation of the bolt while the cap screw is being threaded to the bolt. The retaining element may be constituted by the transverse locking screw described above. An advantage of such embodiments is that the bolt can be made wider to provide increased strength, whilst still being able to accommodate the transverse locking screw.

[0020] The strengthening element may comprise a transverse member to prevent or inhibit axial drilling through the strengthening element. The transverse member may be constituted by a press-fit hardened metal roller or similar. When the strengthening element is constituted by a bolt comprising a head and shaft, the transverse member may be provided in the head or the shaft.

[0021] According to a second aspect of the present invention there is provided a method of fixing a lock cylinder in a lock casing comprising:

providing a lock cylinder according to the first aspect of the invention with the cam located in the gap and contained within the profile of the housing;

inserting the lock cylinder into the lock casing;

inserting a complementary key into the lock cylinder and rotating the key to cause the cam to move out of the gap; and

inserting a strengthening element into the passageway.

[0022] The method may also comprise the step of fixing the lock cylinder in the lock casing, for example, using a transverse fixing element.

[0023] The method may further comprise the step of turning the key to a key removal position and, in doing so, the lost motion of the cam will ensure that the key is able to return to its start position while the cam does not require to return to its location in the gap since this space is now at least partly occupied by the strengthening element.

[0024] It will be understood that after the fixing of the lock cylinder as described above, the key may be rotated through 360° to its insertion and removal position, whilst the cam will move through a lesser angle (e.g. 300° so that it projects by approximately 30° out of each side of the housing when the key is in its insertion/removal position) and this will be sufficient to operate the bolt mechanism without requiring the cam to pass through the gap in the housing which is now occupied by the strengthening element.

[0025] The lock casing may be provided in a door, window, lid or other lockable feature.

[0026] According to a third aspect of the present invention there is provided a bolt comprising a rod having a cable passing longitudinally therethrough and wherein the cable has a first and a second end which serve to retain the cable in the rod.

[0027] The bolt may be suitable for a lock cylinder such as that defined in the first aspect of the invention. However, it is also envisaged that such a bolt would be suitable for other applications. In particular, the bolt is suited to applications in which a retaining function is advantageous since, even if the rod itself is snapped, the cable may hold the bolt together to maintain its retaining function.

[0028] The cable may be constituted by a so-called Bowden cable or a wire rope.

[0029] The cable may be located along the axis of the rod.

Brief Description of the Drawings

[0030] Embodiments of the invention will now be described by way of example only, with reference to the accompanying figures, in which:

Figure 1 shows an end view of a lock cylinder according to a first embodiment of the present invention configured ready for insertion into a lock casing;

Figure 2 shows a longitudinal cross-secflonal view of the lock cylinder of Figure 1;

Figure 3 shows a transverse cross-sectional view taken along line AA of Figure 2;

Figure 4 shows an end view of the lock cylinder of Figures 1 to 3 when fitted with a strengthening element;

Figure 5 shows a longitudinal cross-sectional view of the lock cylinder of Figure 4;

Figure 6 shows a transverse cross-sectional view taken along line BB of Figure 5;

Figure 7 shows a longitudinal cross-sectional view of an alternative strengthening element to that shown in Figures 4 to 6;

Figure 8A shows a longitudinal cross-sectional view of a further strengthening element to that shown in Figures 4 to 6 and 7, in a first orientation;

Figure 8B shows a longitudinal cross-sectional view of the strengthening element of

Figure 8B, rotated by 90° into a second orientation;

Figure 9 shows a partial longitudinal cross-sectional view through a lock cylinder according to an embodiment of the present invention, when fitted to a door;

Figure 10 shows an end view of the lock cylinder of Figure 9; and

Figure 11 shows a longitudinal cross-sectional view of a lock cylinder according to a further embodiment of the invention, when fitted with a strengthening element which is retained in the lock by a cap screw.

Detailed Description of Certain Embodiments

[0031] Figures 1 to 3 illustrate a lock cylinder 10 according to a first embodiment of the present invention, configured ready for insertion into a lock casing (not shown). The lock cylinder 10 comprises a rotatable cylindrical plug 12 which is housed in a non-rotatable housing 14. The housing 14 comprises a cylindrical upper portion 16 and a depending web portion 18. Extending axially into the plug 12 is a keyway 20. Although not shown, the plug 12 and cylindrical upper portion 16 house a pin tumbler mechanism as described in EP0892130 B1.

[0032] As best shown in Figure 2, the housing 14 comprises a first (inner) section 22, a second (outer) section 24 and a connecting section 26 therebetween. A gap 28 is provided between the first section 22 and the second section 24, at a location adjacent the connecting section 26. A longitudinal passageway 29 is provided in the web portion 18 which extends from the first section 22 to the second section 24 and which passes through the gap 28. The passageway 29 terminates in a threaded blind hole 30 provided in the second section 24. A transverse fixing hole 32 is also provided through the connecting portion 26 of the web 18 for receipt of a transverse fixing screw 34 shown in part in Figures 1 and 3.

[0033] A cam 36 is rotatably mounted on the housing 14 and, as shown in Figures 1 to 3, is locatable in the gap 28 so that it is entirely contained within the profile of the housing 14. This allows the lock 10 to be inserted into a standard lock casing having an opening corresponding to the shape of the housing 14.

[0034] In use, the lock cylinder 10 is inserted into a lock casing such as is commonly provided in a door and the transverse fixing screw 34 is then inserted through the hole 32 to secure the lock cylinder 10 in place. A key (not shown), which is configured to operate the lock cylinder 10, is then inserted into the keyway 20 and rotated so as to move the cam 36 out of the gap 28, for example, as shown in Figures 4 to 6. A strengthening element 38 in the form of a threaded bolt is then inserted into the passageway 29 and screwed into the blind hole 30. As shown in Figure 6, when the strengthening element 38 is present in the lock cylinder 10, the cam 36 is not able to enter or pass through the gap 28. Accordingly, the cam 36 is configured for lost motion so that the cam 36 is not required to enter the gap 28 during operation of the lock cylinder 10. The key may, however, be rotated through 360° to its insertion and removal position, whilst the cam 36 will move through a lesser angle of 300° (projecting at an angle of 30° out either side of the housing when the key is in its insertion and removal position) and this is sufficient to operate a bolt mechanism (not shown) to lock or unlock the door.

[0035] It is also noted that, in this embodiment, a clutch (not shown) is included in the cam 36 which allows the key to rotate the cam 36 from either side of the lock cylinder 10, without the other plug 12 at the opposite side of the lock 10 also rotating.

[0036] Figure 7 shows an alternative strengthening element 40 in the form of a bolt 42 comprising a rod 44 having a Bowden cable 46 passing longitudinally therethrough. The cable 46 has a first end 48 and a second end 50 which serve to retain the cable 46 in the rod 44. In the present embodiment, the first end 48 and the second end 50 comprise spherical metal beads of a diameter larger than the channel through which the cable 46 is provided in the rod 44. However, in other embodiments, the first and second ends 48, 50 may comprise other forms of abutments (e.g. cylindrical portions) which have a larger diameter than the channel. In the current embodiment, the bolt 42 also comprises a threaded end 52 and a countersunk head 54 which includes a slot 56 for a screwdriver.

[0037] Figures 8A and 8B show a further possible strengthening element 60 for use with the lock cylinder 10. The strengthening element 60 comprises a first and a second section of rod 62, 64 having a connector 66 extending axially therebetween. The connector 66 is in the form of a spring steel plate which is secured to the two sections of rod 62, 64 by respective pins 68. Similar to the above, the second section of rod 64 comprises a threaded end 70 and the first section of rod 62 comprises a countersunk head 72 which includes a slot (not shown) for a screwdriver.

[0038] Figures 9 and 10 show a variant of the present invention in which the lock cylinder 10 further comprises two escutcheons 80, one on either side of a door 82, and the passageway 29' and the strengthening element 38' both extend through the housing 14 and into the two escutcheons 80 to hold them together. It will be noted that the strengthening element 38' in this case may be as described in relation to any of the above embodiments.

[0039] Figure 11 shows a lock cylinder 100 according to a further embodiment of the invention, when fitted with a strengthening element 101 which is retained in the lock by a cap screw 102. The strengthening element in this case is constituted by a bolt having a threadless outer surface 104 and a threaded hole 106 for receipt of the threaded cap screw 102. The bolt comprises a shaft 108 having a head 110 at one end and the threaded hole 106 provided at the other end. As shown, the threaded hole 106 extends axially part-way into the shaft 108 (in this embodiment the threaded hole 106 extends along approximately one quarter of the length of the shaft 108).

[0040] The cap screw 102 comprises a threaded shaft 112 and an enlarged head 114. The shaft 108 of the bolt further comprises a cut-out 116 for receipt of a retaining element configured to prevent rotation of the bolt while the cap screw 102 is being threaded to the bolt. Although not shown, the retaining element will be constituted by the transverse fixing screw 34 described above. It will also be understood that the cam 36 has been omitted from Figure 11 for clarity, however, the operation of the lock 100 will be the same as described above once the strengthening element 101 has been inserted, the transverse screw 34 fitted and the cap screw 102 positioned as illustrated.

[0041] The head 110 of the strengthening element 101 also comprises a transverse member in the form of a press-fit hardened metal roller 118 to prevent or inhibit axial drilling through the bolt.

[0042] As previously explained, an advantage of the present invention is that the lock cylinder can be retro-fitted to existing lock casings but can also be provided with additional strength in the form of a strengthening element which will not only help to prevent the lock cylinder from being broken in two but may also serve to retain the lock cylinder together even if it is so broken, thereby preventing removal of the lock mechanism and subsequent release of the bolt.

[0043] It will be appreciated by persons skilled in the art that various modifications may be made to the above embodiments without departing from the scope of the present invention as defined by the accompanying claims.

Claims

1. A lock cylinder comprising:

a housing having a first section, a second section and a connecting section therebetween such that a gap is provided between the first section and the second section, at a location adjacent the connecting section; and

a cam rotatably mounted on the housing and which is moveable to a position in which the cam is located in the gap and is contained within the profile of the housing;

wherein the housing has a longitudinal passageway extending from the first section to the second section and which passes at least partly through the gap, the passageway being configured for receiving a strengthening element therethrough; and
wherein the cam is configured for lost motion so that the cam is not required to enter the gap during operation of the lock.

2. The lock cylinder according to claim 1 further comprising a strengthening element.

3. The lock cylinder according to claim 2 wherein the strengthening element comprises one or more of a bolt, screw, rod, pin, bar, plate, cable, wire or chain.

4. The lock cylinder according to either of claims 2 or 3 wherein the strengthening element comprises a rod having a cable passing longitudinally therethrough and wherein the cable has a first and a second end which serve to retain the cable in the rod.

5. The lock cylinder according to any one of claims 2 to 4 wherein the strengthening element comprises two sections of rod having a connector therebetween.

6. The lock cylinder according to any preceding claim further comprising at least one escutcheon and wherein the passageway (and the strengthening element) extend through the housing and into the at least one escutcheon.

7. The lock cylinder according to any preceding claim wherein the housing comprises a cylindrical upper portion and a depending web portion.

8. The lock cylinder according to claim 7 wherein the connecting section and the passageway are both provided in the web portion.

9. The lock cylinder according to claim 7 or 8 wherein a transverse hole is provided through the connecting section of the web for accommodating a transverse locking screw to retain the lock housing in position.

10. The lock cylinder according to claim 2 wherein the strengthening element is retained in the lock by a cap screw.

11. The lock cylinder according to claim 10 wherein the strengthening element is constituted by a bolt having a threadless outer surface and a threaded hole for insertion of a threaded cap screw.

12. The lock cylinder according to claim 11 wherein the shaft of the bolt comprises a cut-out for receipt of a retaining element configured to prevent rotation of the bolt while the cap screw is being threaded to the bolt.

13. A method of fixing a lock cylinder in a lock casing comprising:

providing a lock cylinder according to any preceding claim with the cam located in the gap and contained within the profile of the housing;

inserting the lock cylinder into the lock casing;

inserting a complementary key into the lock cylinder and rotating the key to cause the cam to move out of the gap; and

inserting a strengthening element into the passageway.

14. The method according to claim 13 further comprising the step of fixing the lock cylinder in the lock casing.

15. The method according to claim 13 or 14 further comprising the step of turning the key to a key removal position and, in doing so, the lost motion of the cam will ensure that the key is able to return to its start position while the cam does not require to return to its location in the gap since this space is now at least partly occupied by the strengthening element.

Drawing