GB2634879A

GB2634879A - Thumbturn lock

Info

Publication number: GB2634879A
Application number: GB2316007.0A
Authority: GB
Inventors: Clare Anton
Original assignee: Apecs Consult Ltd
Current assignee: Apecs Consult Ltd
Priority date: 2023-10-19
Filing date: 2023-10-19
Publication date: 2025-04-30
Also published as: GB202316007D0

Abstract

A cylinder lock comprising a rotatable cam, a first and second lock actuation assemblies. The first lock actuation assembly comprises a structural weak point configured to break when subjected to a force above a pre-determined level such that at least a sacrificial portion 1150 of the first lock actuation assembly is removable. The second lock actuation assembly comprises a sleeve 1215 coupled to the cam 1400 such that rotation of the sleeve drives rotation of the cam; a plunger 1210 located within the sleeve; a thumbturn 1205 coupled directly to the sleeve, wherein the thumbturn directly drives rotation of the sleeve; and a biasing element 1245. When the sacrificial portion of the first lock actuation assembly is removed, the biasing element biases the plunger from a first position to a second position (figure 3), and wherein, in the second position, a locking pin 1230 engages a sleeve aperture 1240 and recess in the plunger 1212 to prevent rotation of the sleeve. Upon rotation of the thumbturn and subsequent movement of the plunger, the locking pin 1225 is forced out of engagement with the sleeve aperture thus enabling rotation of the sleeve.

Description

THUMBTURN LOCK

The invention relates generally to a thumbturn lock configured to enable user operation via the thumbturn after snapping. More particularly, but not exclusively, the invention 5 relates to a thumbturn lock configured to enable user operation after snapping via rotation of the thumbturn.

Background

Lock snapping is a common method used by burglars to overcome a door lock to break into a property. The person trying to gain access applies a force to a lock cylinder to snap off a front portion of the lock. The snapped off portion can then be removed, leaving direct access to the cam which is responsible for locking the door.

in order to mitigate this problem, a number of "anti-snap" lock cylinders have been designed with sacrificial mechanisms which move the point of failure away from the centre of the lock cylinder. The most advanced of these designs also include a relocking function which is triggered when a sacrificial portion of the cylinder is snapped away. One such example is shown in patent W020 I SOS I 094A I, wherein the centre of the lock cylinder is made of a reinforced material, and the clutch mechanism in the centre of the lock cylinder is locked in place by a specially configured trap pin when the sacrificial portion of the cylinder lock is broken away from the rest of the lock.

In such designs, the cylinder is kept secure by coupling the cam to an internal/secure side of the lock (i.e.. the side facing inside the building). This solution is used by many existing lock cylinders which accept a key from both sides. The tumblers which secure the internal/secure side of the cylinder (in combination with the relocking mechanism) then prevent operation of the lock cylinder from the external/insecure side. However, this is not a suitable solution for lock cylinders which are operated by rotation of a thumbturn on the internal/secure side.

Lock cylinders which incorporate a relocking mechanism and operate with a thumbturn on the internal/secure side of the cylinder generally require an additional mechanism to achieve the required security without compromising the ability of the user to operate 35 the cylinder from the internal/secure side. Often, this results in a sub-optimal user experience, where thumbturn operation is complicated. This is undesirable, as it is an important safety consideration for locks to be quickly operable, for example, in the event of a fire or other emergency.

The present invention has been devised with the foregoing in mind.

Summary of Invention

According to a first aspect of the invention, there is provided a lock. The lock may be a cylinder lock.

The cylinder lock comprises a rotatable cam. The cylinder lock comprises a first lock actuation assembly disposed on a first side of the cam. The cylinder lock comprises a second lock actuation assembly disposed on a second, opposing side of the cam. Each lock actuation assembly may be configured to selectively rotate the cam to operate the lock.

The first lock actuation assembly comprises a structural weak point configured to break when subjected to a force above a pre-determined level such that at least a sacrificial 20 portion of the first lock actuation assembly is removable from the cylinder lock.

The second lock actuation assembly comprises a thumbturn coupled to the cam and configured to cause rotation of the cam.

The second lock actuation assembly comprises a relocking mechanism configured to prevent rotation of the cam from the first side when the sacrificial portion of the first lock actuation assembly is removed.

Having a relocking mechanism which prevents rotation of the cam ensures that people 30 cannot overcome the lock from the first side. This ensures people cannot break the lock to enter a building without a key.

The relocking mechanism is configured to be unlocked by rotation of the thumbturn. The relocking mechanism is configured to be unlocked by rotation of the thumbturn to enable rotation of the cam. The relocking mechanism may be configured to be unlocked through rotation of the thumbturn alone.

Enabling unlocking of the relocking mechanism via rotation of the thumbturn ensures people inside a building can easily unlock the door to exit the building. Having the thumbturn unlock the relocking mechanism through rotation alone ensures the thumbturn is easy and quick to use, which is beneficial, for example, in the event of an emergency The second lock actuation assembly may comprise a sleeve which couples the thumbturn to the cam. The sleeve may be configured to be rotated by rotation of the thumbturn to cause rotation of the cam. The sleeve may be directly coupled to the thumbturn. The sleeve may be directly coupled to the thumbturn such that the thumbturn directly rotates the sleeve.

The relocking mechanism may comprise a plunger located within the sleeve. The plunger may be moveable by rotation of the thumbturn. The plunger may be configured to be rotated by rotation of the thumbturn.

The relocking mechanism may comprise a pin operable between a first position in which the pin prevents rotation of the sleeve and a second position in which the pin allows rotation of the sleeve. The pin may be operable between the first position and the second position via movement of the plunger within the sleeve caused by rotation of the thumbturn.

The plunger may be operable between a first position and a second position. The plunger may be biased toward the second position when the sacrificial portion of the first lock actuation assembly is removed. When the plunger is in the second position, the pin may be configured to be received within an aperture in the sleeve to prevent rotation of the sleeve.

According to a second aspect of the invention, there is provided a lock. The lock may be a cylinder lock. The cylinder lock of the second aspect of the invention may comprise any features of the cylinder lock of the first aspect, and vice versa.

The cylinder lock comprises a rotatable cam, a first lock actuation assembly, and a second lock actuation assembly.

The first lock actuation assembly may comprise a structural weak point configured to break when subjected to a force above a pre-determined level such that at least a sacrificial portion of the first lock actuation assembly is removable from the cylinder lock.

The second lock actuation assembly may comprise a sleeve. The sleeve may be coupled 10 to the cam such that rotation of the sleeve drives rotation of the cam. The sleeve may be integral with the cam such that they form a single component.

The second lock actuation assembly comprises a plunger located within the sleeve. The sleeve may surround the plunger.

The second lock actuation assembly comprises a thumbturn. The thumbturn may be coupled directly to the sleeve. The thumbturn may be configured to directly drive rotation of the sleeve. In embodiments where the sleeve and the cam form a single component, the thumbturn may be coupled directly to the cam. In embodiments where the sleeve and the cam form a single component, the thumbturn may directly drive rotation of the cam.

The thumbturn may be directly coupled to the plunger. The thumbturn may comprise one or more openings and the plunger may comprise one or more tabs, and vice versa. 25 The tabs may be configured to slot into the openings. The thumbturn may be coupled to the plunger so as to provide 1:1 rotation.

The second lock actuation assembly comprises a biasing element. The biasing element may be spring.

When the sacrificial portion of the first lock actuation assembly is removed, the biasing element may bias the plunger from a first position to a second position. In the second position, a locking pin may engage a sleeve aperture to prevent rotation of the sleeve.

The thumbturn may be configured such that, upon rotation of the thumbturn, the locking pin is forced out of engagement with the sleeve aperture to enable rotation of the sleeve. The thumbturn may be configured such that, upon rotation of the thumbturn alone (i.e., without any other thumbturn movement), the locking pin is forced out of engagement with the sleeve aperture to enable rotation of the sleeve.

Enabling unlocking of the sleeve rotation via rotation of the thumbturn ensures people inside a building can easily unlock the door to exit the building. Having the thumbturn unlock the sleeve rotation using rotation alone ensures the thumbturn is easy and quick 10 to use, which is beneficial, for example, in the event of an emergency.

The plunger and thumbturn may rotate together. The plunger and thumbturn may be configured to partially rotate independently of the sleeve.

The thumbturn may be rotatable through a pre-determined angle before driving rotation of the sleeve. The pre-determined angle may be configured such that the trap pin is never completely out of alignment with the recess. The pre-determined angle may be configured such that the trap pin is never rotated beyond the edge of the recess.

The second lock actuation assembly may comprise a trap pin and a trap spring. The trap spring may be configured to bias the locking pin against the trap pin. When the plunger is in the first position, the trap pin may be retained within the sleeve aperture and may prevent the locking pin from engaging the sleeve aperture. The trap spring may be a trap biasing means, which may be any known spring alternative. Throughout this application, the term "spring" may equally refer to any known spring alternative.

The second lock actuation assembly may comprise a plurality of trap pins. The sleeve may comprise a plurality of sleeve apertures. A trap pin may be disposed within each sleeve aperture. The sleeve apertures may be evenly spread around the circumference 30 of the sleeve.

Having a plurality of trap pins and sleeve apertures may limit the angle through which the cam can rotate before becoming locked.

The second lock actuation assembly may comprise two trap pins located within two sleeve apertures. The second lock actuation assembly may comprise three trap pins located within three sleeve apertures. The second lock actuation assembly may comprise four trap pins located within four sleeve apertures.

When the plunger is in the second position, the trap pin may engage a recess on the surface of the plunger and may enable the locking pin to engage the sleeve aperture to prevent rotation of the sleeve.

The recess on the surface of the plunger may be configured such that, movement of the plunger via the thumbturn forces the trap pin out of the recess to force the locking pin out of engagement with the sleeve aperture.

Rotation of the thumbturn may be configured to drive rotation of the plunger. Rotation 15 of the plunger may be configured to force the trap pin out of the recess to force the locking pin out of engagement with the sleeve aperture.

The second locking mechanism may comprise a connecting pin and a slot. The connecting pin may be retained within the slot so as to provide the coupling between 20 the thumbturn and the sleeve. The slot may be sufficiently wide to enable movement of the locking pin within the slot.

Having a slot wider than the locking pin to enable movement of the locking pin within the slot may enable partial rotation of the thumbturn even when the sleeve is locked.

The locking pin may be part of the sleeve, and the slot may be part of the thumbturn.

The locking pin may be part of the thumbturn, and the slot may be part of the sleeve. The slot may extend partially around the circumference of the sleeve.

The slot may extend less than 180° around the circumference of the sleeve. The slot may extend less than 120° around the circumference of the sleeve. The slot may extend less than 90° around the circumference of the sleeve. The slot may extend less than 45° around the circumference of the sleeve.

The slot may determine the angle through which the thumbturn can rotate independently of the sleeve before driving rotation of the sleeve.

The recess on the surface of the plunger may be a circumferential slot with a graded 5 depth.

The recess on the surface of the plunger may comprise a radially flat wall configured to prevent axial movement of the plunger when the trap pin is engaged with the recess on the surface of the plunger.

The recess on the surface of the plunger may have an inverted dome shape.

The second locking mechanism may be biased such that the thumbturn is configured to rotate into an orientation such that, when the plunger is in the second position, the 15 locking pin engages the sleeve aperture.

The recess may be configured such that, when the trap pin abuts an edge of the recess, the plunger is rotated by the trap pin such that the trap pin abuts the centre of the recess.

The second locking mechanism may comprise a resilient member configured to provide a biasing force to bias the thumbturn into an orientation such that, when the plunger is in the second position, the locking pin engages the sleeve aperture. The resilient member may be a spring. The spring may be a circumferential spring.

The cylinder lock may comprise a clutch for selectively engaging the first lock actuation assembly with the cam. The dutch may be movable between a first and second position together with the plunger. When the clutch is in the second position, the first lock actuation assembly may not engage the cam.

The cylinder lock may comprise a clutch locking pin and a clutch locking pin spring. When the clutch is in the second position, the clutch locking pin spring may bias the clutch locking pin into engagement with a clutch recess so as to axially fix the clutch in the second position. The clutch locking pin spring may be a clutch locking biasing element, which may be any known alternative to a spring.

The cylinder lock may comprise a motor configured to rotate the thumbturn. The motor may be operated by a processor.

Optional features of any of the above aspects may be combined with the features of any other aspect, in any combination. For example, features described in connection with the cylinder lock of the first aspect may have corresponding features definable with respect to the door of the third aspect, and vice versa, and these embodiments are specifically envisaged. Features which are described in the context or separate aspects and embodiments of the invention may be used together and/or be interchangeable wherever possible. Similarly, where features are, for brevity, described in the context of a single embodiment, those features may also be provided separately or in any suitable sub-combination.

Brief description of the drawings

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures 1(a) and 1(b) respectively show cross-section& side views of a cylinder lock 20 according to the present invention before and after snapping; Figure 2 shows an enlarged cross-sectional side view of the cylinder lock prior to snapping; Figure 3 shows an enlarged cross-sectional side view of the cylinder lock after snapping; Figure 4 shows an enlarged cross-sectional side view of the cylinder lock after snapping and with the plunger rotated relative Lo Figure 3; Figure 5 shows a perspective view of the connection between the thumbturn and the sleeve; Figures 6(a) and 6(b) respectively show perspective views of a plunger and a 35 thumbturn; Figures 7(a) and 7(b) respectively show perspective views of plungers for use in cylinder locks according to the present invention; and Figure 8 shows an axial cross-section of the plunger within the sleeve.

Detailed description

Figure la shows a cross-sectional side view of a cylinder lock 1000 according to an 10 embodiment of the invention.

The cylinder lock comprises a rotatable cam 1400, a first lock actuation assembly 1100, and a second lock actuation assembly 1200.

The first lock actuation assembly 1100 is positioned on a first side of the cam 1400 and the second lock actuation assembly 1200 is positioned on a second side of the cam 1400. in use, the cylinder lock 1000 is configured for use inside a door (e.g., a door at the entrance of a building) and is fitted such that the first side faces outside of the door (i.e., it faces the outside of the building) and the second side faces inside of the door (i.e., it faces the inside of the building). The cam 1400 is configured to rotate so as to lock the door (for example, by moving a bolt or other external component).

The cylinder lock 1000 comprises a clutch 1300. The clutch 1300 is configured to selectively provide engagement between the first lock actuation assembly 1100 and the 25 cam 1400 such that the first lock actuation assembly can be used to rotate the cam 1400.

The first lock actuation assembly 1100 is configured to enable rotation of the cam 1400 using a key. In use, a user inserts a key into the first lock actuation assembly 1100 to displace pins 1110. When the key is inserted into the first lock actuation assembly 1100, the clutch 1300 provides engagement between the first lock actuation assembly 1100 and the cam 1400, such that the user can rotate the cam 1400 by rotating the key.

The first lock actuation assembly 1100 comprises a structural weak point configured to break when subjected to a force above a pre-determined level. When the first lock 35 actuation assembly 1100 is subjected to a force exceeding the pre-determined level, a sacrificial portion 1150 of the first lock actuation assembly 1100 breaks away, as shown in Figure lb. In other embodiments, different clutch mechanisms can be used, or the clutch 5 mechanism can be omitted entirely. in other embodiments, different first locking mechanisms can be used. In some embodiments, the first locking mechanism may not comprise pins.

The second lock actuation assembly 1200 is configured to enable rotation of the cam 1400 via rotation of a thumbturn (shown in Figure 2).

Figure 2 shows an enlarged cross-sectional side view of the cylinder lock 1000 prior to the sacrificial portion 1150 being removed.

The second lock actuation assembly 1200 comprises a sleeve 1215. The sleeve 1215 is coupled to the cam 1400. The coupling between the sleeve 1215 and the cam 1400 is configured such that rotation of the sleeve 1215 causes a 1:1 rotation with the cam 1400, and vice versa. In some embodiments, the sleeve 1215 and the cam 1400 are connected so as to form a single component.

The second lock actuation assembly 1200 comprises a thumbturn 1205. The thumbturn 1205 is directly coupled to the sleeve 1215 and is configured to drive rotation of the sleeve 1215. As explained above, rotation of the sleeve 1215 causes rotation of the cam 1400, and so the cam 1400 is rotatable via the thumbturn 1205.

The connection between the thumbturn 1205 and the sleeve 1215 is shown in greater detail in Figure 5. The thumbturn 1205 comprises a connecting pin 1220. The sleeve 1215 comprises a slot 1250 which extends partially around the circumference of the sleeve 1215. The connecting pin 1220 is retained within the slot 1250 so as Lo provide direct coupling between the thumbturn 1205 and the sleeve 1215. The slot 1250 is wider than the connecting pin 1220 such that thumbturn 1205 is free to partially rotate relative to the sleeve 1215 (i.e., rotate through a small angle) before abutting an edge of the slot 1250 to drive rotation of the sleeve 1215. In alternative embodiments, the connecting pin can be part of the sleeve and the slot can be part of the thumbturn Returning now to Figure 2, the second lock actuation assembly 1200 comprises a plunger 1210. The plunger 1210 is disposed within the sleeve 1215 such that the sleeve surrounds the plunger 1210. The second lock actuation assembly 1200 comprises a biasing spring 1245. The biasing spring 1245 exerts a biasing force upon the plunger 1210 in the direction of the clutch 1300 (i.e., to the left in Figure 2) so as to provide abutment between the plunger 1210 and the clutch 1300. The biasing spring 1245 is disposed between the thumbturn 1205 and the plunger 1210. The skilled person will recognise that, in other embodiments, the biasing spring 1245 can be replaced with an alternative biasing element, such as an elastic member.

The plunger 1210 is coupled to the thumbturn 1205 such that rotation of the thumbturn 1205 causes rotation of the plunger 1210. The coupling of the thumbturn 1205 with the plunger 1210 according to an embodiment of the invention is described below with reference to Figures 6(a) and 6(b).

Figures 6(a) and 6(b) respectively show perspective views of a plunger 1210 and a thumbturn 1205. The plunger 1210 comprises tabs 1224 which are configured to slot into corresponding openings 1222. When the tabs 1224 are positioned within the openings 1222, rotation of the thumbturn 1205 drives rotation of the plunger 1210. The openings 1222 are longer than the tabs 1224 such that the plunger 1210 can move axially with respect to the thumbturn 1205.

In other embodiments, the plunger 1210 is not coupled so as to rotate with the thumbturn 1205 and may instead be configured to move axially in response to rotation of the 25 thumbturn 1205.

The thumbturn 1205 comprises a central aperture 1216 and the plunger 1210 comprises a central aperture 1214. The central apertures 1214, 1216 are configured to retain the biasing spring 1245 between the plunger 1210 and the thumbturn 1205.

The thumbturn 1205 comprises an aperture 1218 configured to receive the connecting pin 1220.

The plunger 1210 comprises a recess 1212. In the embodiment shown, there are four recesses 1212 evenly spread around the circumference of the plunger 1210, but in other embodiments there may be one recess, or any plurality of recesses.

Returning again to Figure 2, the second lock actuation assembly 1200 comprises a trap spring 1235, a locking pin 1230, and a trap pin 1225. The trap spring 1235 exerts a radially inward biasing force upon the locking pin 1230, which in turn exerts a radially inward force upon the trap pin 1225. The trap pin 1225 is disposed within a sleeve aperture 1240 and abuts the surface of the plunger 1210.

In the embodiment of Figure 2, there are four trap pins 1225 (only two are shown), with each trap pin 1225 disposed in a corresponding sleeve aperture 1240. The sleeve apertures 1240 (together with the trap pins 1225) are evenly spread around the circumference of the sleeve 1215 such that there is a 90° angle between each sleeve aperture 1240.

in other embodiments, the cylinder lock may comprise one trap pin, one trap spring, and one locking pin. In other embodiments, the cylinder lock may comprise any plurality of trap pins, any plurality of trap springs, and any plurality of locking pins.

The clutch 1300 comprises a clutch recess 1305 on its surface.

The cylinder lock 1000 comprises a clutch locking pin 1110 and a clutch locking pin spring 1105. The clutch locking pin spring 1105 exerts a radially inward biasing force 25 against the clutch locking pin 1110. In Figure 2, the clutch locking pin 1110 abuts an outer surface of the clutch 1300.

Figure 3 shows a cross-sectional side view of the cylinder lock 1000 in the snapped s talc.

Following removal of the snapped sacrificial portion 1150 (shown in Figure lb), the biasing spring 1245 exerts a force onto the plunger 1210, displacing the plunger 1210 and the clutch 1300 from a first position into a second position.

When the plunger 1210 is in the second position, the recess 1212 on the surface of plunger 1210 aligns with the trap pin 1225. The biasing force from the trap spring 1235 forces the trap pin 1225 partially out of the sleeve aperture 1240 such that the trap pin 1225 engages the recess 1212. The locking pin 1230 partially enters the sleeve aperture 1240 to occupy the space previously occupied by the trap pin 1225 so as to engage the sleeve aperture 1240.

When the locking pin 1230 is engaged with the sleeve aperture 1240 (i e., partially retained within the sleeve aperture 1240), the sleeve 1215 cannot rotate. Upon 10 attempted rotation, edges of the sleeve aperture 1240 abut the locking pin 1230, meaning the sleeve 1215 cannot rotate.

Because the sleeve 1215 is coupled to the cam 1400, preventing rotation of the sleeve 1215 prevents rotation of the cam 1400. Therefore, the cam 1400 cannot be rotated by 15 a user trying to rotate the cam 1400 from the first side of the lock 1000.

if the thumbtum 1205 is rotated between 0 and 90° relative to the position shown in Figure 2 prior to removal of the sacrificial portion 1150, the locking ph 1230 will not be aligned with the sleeve aperture 1240 and so the cam 1400 rotation will not be locked immediately. However, since there are four equally spaced trap pins 1225, the cam 1400 cannot rotate by more than 90° without aligning a trap pin 1225 with a recess 1212, thereby locking rotation.

A user can still rotate the cam 1400 via the thumbtum 1205, as explained below.

in the embodiment of Figures 1-4, the plunger 1210 is configured to rotate together with the thumbtum. As discussed above, the thumbturn 1205, and therefore the plunger 1210, are able to partially rotate before the connecting pin 1220 abuts the edge of slot 1250 of the sleeve 1215. Therefore, the plunger 1210 is roimable through a small angle (which depends upon the length of the slot 1250) even whilst the sleeve 1215 is locked.

The recess 1212 on the surface of the plunger 1210 is curved such that, upon rotation of the plunger 1210, the trap pin 1225 is forced out of the recess 1212 and back into 35 the sleeve aperture 1240, which displaces the locking pin 1230 to move it out of sleeve aperture 1240, as shown in Figure 4. In the position shown in Figure 4, the locking pin 1230 is no longer engaged with the sleeve aperture 1240, meaning the sleeve 1215, and therefore the cam 1400, are free to rotate. Therefore, rotation of the plunger 1210 via the thumbturn 1205 unlocks the rotation of the sleeve 1215 and the cam 1400.

Plungers according to embodiments of the invention are shown in detail in Figure 7(a) and 7(b).

Figure 7(a) shows a perspective view of the plunger 1210 shown in each of Figures 14. The plunger 1210 comprises four recesses 1212 equally spaced around the circumference of the plunger 1210. Each recess 1212 is shaped as an inverted dome.

From the position shown in Figure 3, as the plunger 1210 rotates, the trap pin 1225 is 15 pushed back into the sleeve aperture 1240 as it moves across the sloped sides of the recess 1215.

In other embodiments of the invention, the plunger 1210 is not configured to rotate together with the thumbturn 1205. instead, the plunger 1210 can be configured to move axially (i.e., left or right in Figures 1-4) in response to rotation of the thumbturn 1205 when the clutch 1300 is in the second position. In such embodiments, the axial movement of the plunger 1210 forces the trap pin 1225 out of the recess 1212 back into the sleeve aperture 1240 to unlock rotation of the sleeve 1215. In some embodiments, before the lock 1000 is snapped, and the clutch 1300 is in the first position, rotation of the thumbturn 1205 increases/decreases tension in the biasing spring but does not move axially displace the plunger 1200.

For embodiments using the plunger of Figure 7(a), a user could exert an axial force upon the exposed clutch 1300 Lo force the trap pin 1225 ouL of the recess 1212 Lo 30 unlock rotation of the cam 1400. To prevent this, alternative plungers, such as the plunger of Figure 7(b), can be used.

Figure 7(b) shows a perspective view of a plunger 2210 according to a different embodiment. The plunger 2210 comprises recesses 2212 having two flat radial walls, 35 and an inwardly curved surface. Rotation of the plunger 2210 forces the trap pin 1225 back into the sleeve aperture 1240, similarly to the plunger of Figure 7(a). However, the flat radial walls prevent axial movement of the plunger when the trap pin 1225 is engaged with one of the recesses 2212. In such an embodiment, axial forces exerted upon the clutch 1300 by a user cannot unlock rotation of the cam 1400 and the sleeve 1215, as the trap pin 1225 abuts the flat radial walls and cannot disengage with the recess 2212.

In other embodiments, the recess on the plunger is a circumferential slot with a graded depth. The circumferential slot can have flat radial walls, similarly to the recesses in Figure 7(b).

In some embodiments, to ensure that rotation of the sleeve 1215 and cam 1400 is relocked after being unlocked via thumbturn 1205 rotation, the first locking mechanism 1100 comprises a resilient member 1255, such as a spring, which biases the thumbturn and plunger 1210 back to their original positions relative to the sleeve 1215 in the absence of an external force from the user. In some embodiments, the spring is a circumferential spring. Figure 5 shows a perspective view of an embodiment in which the resilient member 1255 is clearly shown.

Alternatively, instead of using a resilient member 1255, the recesses can be configured to provide the biasing force, as explained with reference to Figure 8.

Figure 8 shows an axial cross section of the lock 1000 according to an embodiment of the invention. The plunger 1210 is shown within the sleeve 1215. The firing pins 1225 25 are visible within the four sleeve apertures 1240. The locking pin 1230 and trap spring 1235 are also shown.

As explained above, rotation of the thumbturn 1205 (and therefore the plunger 1210) is restricted relative to the sleeve 1215, and the rotational limits are determined by the length of the slot 1250. in the position shown in Figure 8, the thumbturn 1205 and plunger 1210 are rotated as far as possible relative to the sleeve 1215. The rotational limits of the thumbturn 1205 ensure that the firing pin 1225 never completely disengages with the recess 1212. In the absence of any external force, the trap spring (not shown) exerts an inward radial force upon one of the firing pins 1225, thereby forcing the firing pin 1225 into the recess 1212 which rotates the plunger 1210 (and thumbturn 1205) back into a neutral position in which the sleeve 1215 rotation is locked.

To provide an additional level of security to the cylinder lock 1000, axial movement of the clutch 1300 can be locked once it is moved from the first position (as shown in Figure 2) into the second position (as shown in Figure 3 and 4). The locking is provided by the clutch recess 1305, the clutch locking pin 1110, and the clutch locking pin spring 1105.

As explained earlier in the description, when the clutch 1300 is in the first position, as shown in Figure 2, the clutch locking pin spring 1105 biases the clutch locking pin 1110 against the surface of the clutch 1300. When the clutch 1300 moves into the second position, as shown in Figures 3 and 4, the clutch locking pin spring 1105 biases the clutch locking pin 1110 into engagement with the clutch recess 1305. The clutch recess 1305 has radially flat walls which abut the clutch locking pin 1110 to prevent axial movement of the clutch 1300. Preventing axial movement of the clutch 1300 ensures that the clutch cannot be used to exert an axial force upon the plunger 1200 From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of cylinder locks, and which may be used instead of, or in addition to, features already described herein.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided 35 separately or in any suitable sub-combination. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, a single processor or other unit may fulfil the functions of several means recited in the claims and any reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

Claims 1. A cylinder lock comprising: a rotatable cam; a first lock actuation assembly; and a second lock actuation assembly; wherein the first lock actuation assembly comprises a structural weak point configured to break when subjected to a force above a pre-determined level such that at least a sacrificial portion of the first lock actuation assembly is removable from the cylinder lock; wherein the second lock actuation assembly comprises: a sleeve, wherein the sleeve is coupled to the cam such that rotation of the sleeve drives rotation of the cam; a plunger located within the sleeve; a thumbturn coupled directly to the sleeve, wherein the thumbturn is configured to directly drive rotation of the sleeve; and a biasing element; wherein, when the sacrificial portion of the first lock actuation assembly is removed, the biasing element biases the plunger from a first position to a second 20 position, and wherein, in the second position, a locking pin engages a sleeve aperture to prevent rotation of the sleeve; and wherein, the thumbturn is configured such that, upon rotation of the thumbturn, the locking pin is forced out of engagement with the sleeve aperture to enable rotation of the sleeve.
2. The cylinder lock of claim 1, wherein the second lock actuation assembly further comprises a trap pin and a trap spring, the trap spring configured to bias the locking pin against the trap pin, and wherein, when the plunger is in the first position, the trap pin is retained within the sleeve aperture and prevents the locking pin from engaging the sleeve aperture.
3. The cylinder lock of claim 2, wherein, when the plunger is in the second position, the trap pin engages a recess on the surface of the plunger and enables the locking pin to engage the sleeve aperture to prevent rotation of the sleeve.
4. The cylinder lock of claim 3, wherein the recess on the surface of the plunger is configured such that, movement of the plunger via the thumbturn forces the trap pin out of the recess to force the locking pin out of engagement with the sleeve aperture.
5. The cylinder lock of claim 4, wherein rotation of the thumbturn is configured to drive rotation of the plunger, and rotation of the plunger is configured to force the trap pin out of the recess to force the locking pin out of engagement with the sleeve aperture.
6. The cylinder lock of any preceding claim, wherein the second locking mechanism comprises a connecting pin and a slot, wherein the connecting pin is retained within the slot so as to provide the coupling between the thumbturn and the sleeve, and wherein the slot is sufficiently wide to enable movement of the locking pin within the slot.
7. The cylinder lock of any of claims 3-6, wherein the recess on the surface of the plunger is a circumferential slot with a graded depth.
8. The cylinder lock of any of claims 3-7, wherein the recess on the surface of the plunger comprises a radial wall configured to prevent axial movement of the plunger 20 when the trap pin is engaged with the recess on the surface of the plunger.
9. The cylinder lock of any of claims 3-6, wherein the recess on the surface of the plunger is an inverted dome shape.
10. The cylinder lock of any preceding claim, wherein the second locking mechanism is biased such that the thumbturn is configured to move into an orientation such that, when the plunger is in the second position, the locking pin engages the sleeve aperture.
II. The cylinder lock of claim 10, wherein the second locking mechanism further comprises a resilient member configured to provide a biasing force to bias the thumbturn into an orientation such that, when the plunger is in the second position, the locking pin engages the sleeve aperture.
12. The cylinder lock of claim 11, wherein the resilient member s a spring.
13. The cylinder lock of any preceding claim, further comprising a clutch for selectively engaging the first lock actuation assembly with the cam, wherein the clutch is movable between a first and second position together with the plunger; and wherein, when the clutch is in the second position, the first lock actuation assembly does not engage the cam.
14. The cylinder lock of claim 13, further comprising a clutch locking pin and a clutch locking pin spring, and wherein, when the clutch is in the second position, the 10 clutch locking pin spring biases the dutch locking pin into engagement with a clutch recess so as to axially fix the clutch in the second position.
15. The cylinder lock of any preceding claim, wherein the cylinder lock comprises a motor configured to rotate the thumbturn.