GB2624450A

GB2624450A - High security lock cylinder

Info

Publication number: GB2624450A
Application number: GB2217322.3A
Authority: GB
Inventors: Stubbs Tim; Bilton Simon; Mascord Adam
Original assignee: Era Home Security Ltd
Current assignee: Era Home Security Ltd
Priority date: 2022-11-18
Filing date: 2022-11-18
Publication date: 2024-05-22
Also published as: EP4372189A1; CN220434465U; GB202217322D0

Abstract

A cylinder lock 1 having a lock barrel, a cam 5, and a clutch mechanism for connecting the lock barrel 6 and the cam upon insertion of a key into the lock barrel. The clutch mechanism has a rotor 41 for transferring a rotation from the lock barrel to the cam. The lock has a security mechanism comprising a locking portion 9 configured such that the locking portion is rotatable between a first condition wherein the rotor is rotatable, and a second condition wherein the locking portion blocks the rotor from rotating. The cylinder lock is designed to automatically secure the cam if the lock is snapped by an attacker and the first lock housing is removed or disconnected from the cylinder lock. The security mechanism may include a biasing mechanism, e.g. a spring which rotates the locking portion 9 into the second condition. The locking portion 9 may have a bolt with bolt head (96 Fig 8/9) which enters a circumferential groove (48 Fig 4) in the rotor in the second condition preventing it from moving.

Description

High security lock cylinder

Technical Field

The invention relates to cylinder locks for doors and windows. More specifically, the invention relates to high security cylinder locks which provide resistance to lock snapping.

Background

The "euro-profile" lock cylinder (also known as the "euro-cylinder") is a common, commercially available lock style for use in doors and windows. The locks are typically integrated into larger locking mechanisms and comprise a central cam which actuates the rest of the lock mechanism. Euro-profile lock cylinders have a known vulnerability to lock-snapping', wherein the lock can be snapped in half and at least partly removed.

This allows an attacker or burglar access to the rest of the locking mechanism, which can then be manually actuated and access to a building obtained.

One solution to the problem of lock-snapping is to increase the strength of the whole lock cylinder such that it is not possible to snap in situ with simple tools. Examples of such a lock cylinder are described by the present Applicant in EP3022370. However, the increased size of such locks make them incompatible with existing door locking mechanisms configured for receiving a euro-profile lock.

A further solution to the problem of lock snapping is to provide the lock cylinder with a frangible portion located between the central cam and the external surface of the lock cylinder. When such locks are attacked, they snap preferentially at the frangible portion so that only a portion of the lock is removed and the remainder prevents access to the cam. A clutch mechanism is typically employed to ensure that the lock cylinder is operable from the inside, while a security mechanism prevents actuation of the lock from the external side. Examples of such locks are described in EP2300673, EP2730727 and GB2591154. While these locks provide a high level of security, the clutch and security mechanisms are often intricate and complex, which increases cost and has potential for failure.

The present invention aims to mitigate or ameliorate one or more of the above problems, or provide a useful alternative.

Summary of invention

According to a first aspect of the invention, there is provided a cylinder lock. The cylinder lock may comprise a lock barrel and a cam. The cylinder lock may comprise a clutch mechanism. The clutch mechanism may be configured to connect the lock barrel and the cam upon insertion of a key into the lock barrel. The clutch mechanism may comprise a rotor. The rotor may be configured to transfer a rotation from the lock barrel to the cam. The cylinder lock may comprise a security mechanism. The security mechanism may comprise a locking portion. The locking portion may be configured such that the locking portion is rotatable between: a first condition wherein the rotor is rotatable, and a second condition wherein the locking portion blocks the rotor from rotating.

The cylinder lock is advantageous, since the locking portion is capable of preventing further actuation of the cylinder lock once it has been put into the second condition. For example, the cylinder lock may be configured to put the locking portion into the second condition automatically e.g. upon snapping of the lock.

The cam may be located adjacent to the lock barrel. The lock barrel may be provided in a first lock housing. The cam may be provided in a cam housing. The cylinder lock may comprise a frangible portion or connection between the first lock housing and the cam housing. A frangible portion or connection is advantageous, since it ensures the lock snaps preferentially in a position whereby the cylinder lock can maintain its locking function and/or put the locking portion into the second condition.

The cylinder lock may be configured such that the second condition is caused by the first lock housing being removed and/or disconnected from the cylinder lock. For example, the second condition may be caused by the first lock housing being removed and/or disconnected from the cam housing.

The first lock housing may comprise a retainer configured to retain the locking portion in the first condition. The locking portion may comprise a contact surface or recess configured to engage the retainer when in the first condition. The retainer and/or locking portion may be configured such that the retainer prevents the locking portion from rotating in use (e.g. in the first condition). The retainer may comprise a tooth. The retainer may extend from the surface of the first locking housing.

The security mechanism may comprise a biasing mechanism configured to rotate the locking portion into the second condition. The second condition may by triggered by the retainer being moved from the contact surface or recess. The biasing mechanism may comprise a spring, such as a torsion spring.

The rotor may comprise a recess. The locking portion may comprise a bolt. The recess and/or bolt may be configured such that the bolt engages the recess when in the second condition. The bolt may comprise a portion of the locking portion e.g. a bolt head may be provided on the locking portion.

The rotor may comprise a circumferential groove. A part of the locking portion may be received within the circumferential groove. For example, the bolt and/or bolt head may be received within the circumferential groove. The recess may be provided in or contiguous with the circumferential groove. The bolt may be received within the circumferential groove when the locking portion is in the first condition. The bolt and/or bolt head may extend from the circumferential groove when the locking portion is in the second condition e.g. to engage the recess. The bolt portion may comprise a bolt head which, when rotated into the second condition, engages at least one shoulder of the recess. The bolt head may be elongate or oblong shaped. The bolt may have one or more curved surfaces to aid its rotation.

The locking portion may be rotatable through 900 between the first and second conditions. The locking portion may comprise a locking pin with a bolt on the end thereof. The locking portion may have an axis of rotation which is perpendicular to the elongate axis of the cylinder lock. The locking portion may have an axis of rotation which is perpendicular to the axis of rotation of the rotor.

The locking portion may comprise a restrictor mechanism. The restrictor mechanism may be configured to prevent the locking portion from returning to the first condition once in the second condition. The restrictor mechanism may comprise a restrictor portion configured to restrict rotation of the locking portion when in the second condition. The restrictor may comprise a tooth configured to engage a recess or aperture in the locking portion or vice versa. The restrictor may be biased such that it automatically engages the recess or aperture when aligned. The restrictor may comprise a spring arm.

The rotor may be rotationally locked to the barrel i.e. the rotor and barrel may be unable to rotate relative to each other such that rotation of one causes the rotation of the other.

The clutch mechanism may further comprise at least one clutch. The at least one clutch may be axially moveable e.g. relative to the cam and/or to engage and disengage the cam.

In one series of embodiments, the clutch mechanism comprises a first and a second clutch. The first clutch may be configured to transfer a rotation from the rotor (e.g. a first rotor) to the cam (e.g. when the first clutch and cam are engaged). The first and second clutch may be rotatable independently of each other. The first clutch may be rotationally locked to the rotor. The cylinder lock may comprise a second lock barrel or a thumb turn assembly e.g. located on the opposite side of the cam to the first lock barrel, and subsequently herein referred to as a 'second lock barrel'. The second lock barrel may be locatable on the internal side of a locking assembly. The second clutch may be rotationally locked or lockable to the second barrel.

The clutch mechanism may be configured such that in a default condition, the first clutch is disengaged from the cam. That is, the cam and first clutch are rotatable relative to each other e.g. by actuation of the cam from the second clutch. The clutch mechanism may be configured such that inserting a key into the barrel moves the first clutch into engagement with the cam and/or moves the second clutch out of engagement with the cam. The clutch mechanism may be configured such that upon insertion of a key into the second lock barrel, the second clutch engages the cam and disengages the first clutch from the cam and/or axially displaces the first clutch.

In a further series of embodiments, the first clutch comprises a pressure plate and a drive plate. The pressure plate and drive plate may be axially movable relative to the rotor and the cam. The pressure plate and drive plate may be rotationally locked with the rotor and/or to each other. The pressure plate may be configured to be moved axially by a key and/or by a pusher actuated by a key e.g. toward the cam. The pressure plate may comprise an interlocking formation on a first side thereof which locks with a cooperating formation on or in the rotor. The other side of the pressure plate may be configured to contact the cam but not to engage directly therewith. The drive plate may comprise a drive connecting formation which engages a corresponding recess on the pressure plate (e.g. a tooth and recess) and selectively engages a cooperating formation (e.g. a recess) on or in the cam. The tooth and recess combination may be in either configuration between pressure plate and drive plate. The drive plate may be moved axially by the pressure plate and/or may be rotationally locked to the pressure plate. The first clutch may comprise a first clutch drive spring between the pressure plate and drive plate. In use, the pressure plate may be axially driven by the insertion of a key toward the cam. If the drive tooth and cam recess are misaligned, the movement of the pressure plate compresses the first clutch drive spring. Subsequent rotation of the first clutch via the rotor thus allows the drive tooth to become aligned with the cam recess, whereby the first clutch drive spring drives the drive plate axially such that the drive tooth engages with the cam recess and thus rotationally locks the first clutch and the cam. The clutch mechanism may comprise a clutch default spring configured to bias the first clutch into a disengaged position relative to the cam.

The second clutch may comprise a second rotor and a drive connector. The second rotor may be located within a cam ring on the cam housing, or it may be located within a second lock housing. The second rotor may be connected to and rotationally fixed to the cam e.g. by corresponding formations such as one or more teeth and recesses. The rotor may be rotatable relative to the second lock barrel (or thumb turn assembly). The drive connector may extend between the second rotor and the second lock barrel and may be axially movable between a position wherein the drive connector engages both and a position whereby the drive connector is disengaged from at least one of the second rotor and the second lock barrel. The drive connector may comprise at least one connecting portion which prevent relative rotation of the second rotor and second lock barrel when the drive connector is engaged with both. For example, the drive connector may comprise an arm or tooth, or may have an polygonal cross-section. In some embodiments, the drive connector is disengaged from the second rotor in a default state and engages the second rotor when a key is inserted into the second lock barrel or a thumb turn assembly is actuated. Alternatively, the drive connector may engage both the second rotor and the second lock barrel in a default state.

The clutch mechanism may be configured such that when a key is inserted into the first lock barrel, the drive connector is disengaged from the second rotor, such that the cam and second rotor may be rotatable by the first clutch (relative to the second barrel). The clutch mechanism may comprise a clutch pin. The clutch pin may connect the first and second clutches e.g. to ensure that when one clutch engages the cam, the other clutch is disengaged. The clutch pin may connect the pressure plate and the drive connector.

The clutch pin may extend through one or more of the drive plate, cam, and second rotor. The clutch pin may comprise a drive plate surface for bearing upon the drive plate. The clutch default spring noted above may be configured to bear upon the clutch pin, thereby biasing the first clutch into a disengaged position.

The above clutch mechanism is advantageous, since it ensures that both the first and second clutch mechanism can engage the cam upon insertion of a key into respective first and second lock barrels, even if the cam is misaligned with the drive plate or drive connector. The springs therein are compressed until the keys are rotated and the clutch mechanism aligned, at which point the springs bias the drive plate or drive connector into engagement with the cam automatically.

Brief description

Embodiments of the invention will now be described with reference to the following Figures in which: Figure 1 is a perspective view of a cylinder lock, Figure 2 is a side view of a cylinder lock, Figure 3 is an exploded diagram of the cylinder lock, Figures 4a and 4b are perspective views of a rotor, Figure 5 is an exploded view of a first and second clutch, Figure 6 is an axial view of a cam, Figure 7 is a cross-section through a cam housing and security mechanism, Figure 8 is a perspective view of a locking portion, Figures 9a and 9b are perspective views of a locking portion in first and second conditions respectively, Figure 10 is a cross-section through a cylinder lock in normal use, Figure 11 is the cross-section of figure 10 after the cylinder lock has been broken, and Figure 12 is an exploded diagram of a further embodiment of cylinder lock.

Specific description

Turning now to Figures 1 to 3, there is shown a cylinder lock 1. The cylinder lock 1 has a first lock housing 2 and a second lock housing 3 located on either side of a centrally located cam housing 4. The first lock housing 2 is provided with a lock barrel 6 within the barrel opening 60, and the second lock housing 3 is provided with a thumb turn 7 within the barrel opening 70. In alternative embodiments, the thumb turn 7 may be replaced with a second key-operated lock barrel. The cam housing 4 is provided with a cam 5 which is rotatable relative to the cam housing 4 in use. The first and second lock housings 2, 3 each have an axial aperture 35 therein which is located over the pegs 44 extending from the cam housing 4. The lock housings 2, 3 are secured by securing pins 22, 32 which pass through apertures 21, 31 and the pegs 44 to secure the lock 1 together. The pegs 44 act as a weakened frangible region such that the lock 1 would break preferentially at or about the pegs 44 rather than through the centre of the cam housing 4.

The lock barrel 6 is provided with a series of displaceable locking pins 61 which extend within channels (not shown) inside the first lock housing 2 and the lock barrel 6. The locking pins prevent relative rotation of the barrel 6 within the first lock housing 2 unless a coded key is inserted and the locking pins 61 depressed in the conventional manner. The first and second lock housing 2, 3 are provided with bores 23, 33 which extend parallel to the channels and locking pins 61. The bores 23 are provided with anti-drill pins i.e. toughened metal pins which resist an attacker drilling through the lock housings to remove the locking pins 61. The bores 33 are located on an internal side of the lock 1, and thus are not provided with anti-drill pins.

The first and second lock housings 2, 3 each have a pair of securing pin apertures 24, 34 which extend vertically into and through the barrel openings 60, 70. The first lock housing 2 is provided with a pair of barrel securing pins 62 which extend through the securing pin apertures 24 and, when assembled, are located within the annular groove 63 in the end of the barrel 6. The barrel securing pins 62 thus act as a collar which secures the barrel 6 in position while allowing the barrel 6 to rotate. In the embodiment shown, securing pin apertures 34 in the second lock housing are not used. In alternative embodiments with an internal lock barrel, the securing pin apertures 34 would be used to retain a second lock barrel as described above. The first and second lock housings 2, 3 are identical which reduces the number of unique components required to form the lock, and the various securing apertures can be utilised (or not) as required for the particular configuration of lock to be produced. In some embodiments, the first and second lock housings 2, 3 may be different lengths to each other, but otherwise the same. Locks are typically provided in a range of different lengths in order for compatibility with varying locking assemblies.

The cam housing 4 has a pair of arms with cam rings 45 located on the end. Within the cam ring 45 adjacent to the first lock housing 2 is a rotor 41. The cam ring 45 is provided with a pair of cam pin apertures 42 which extend into the opening in the cam ring 45 and receive rotor pins 43. The rotor pins 43, in use, sit within the circumferential groove 411 in the outer circumferential surface of the rotor 41 to secure the rotor 41 axially within the cam ring 45 while allowing free rotation. The face of the rotor 41 facing the barrel 6 is provided with a pair of sockets 412 for receiving projections 64 extending from the barrel 6, and thus rotationally lock the barrel 6 and rotor 41 together (i.e. preventing relative rotation). As shown in Figures 4a and 4b, the rotor 41 is also provided with a circular central aperture 46 extending axially through the rotor 41, and a recess 47 which extends partially through the rotor 41. The recess 47 is cuboidal, but could be any alternative non-circular shape. The rotor 41 is also provided with a locking recess 48 with an approximately square cross-section on its outer circumferential surface. The locking recess 48 has a depth equal to the depth of the circumferential groove 411, but a width greater than the circumferential groove 411, such that two pairs of shoulders 49 are formed on each side of the circumferential groove 411.

With further reference to Figures 5 and 6, there is shown the first and second clutches 81, 82 and the cam 5. In use, the first and second clutches 81, 82 are located within the cam 5 positioned between the two cam rings 45. The first clutches 81, 82 are approximately circular discs with a pair of clutch recesses 811, 821 in the outer edge.

The first clutch 81 is provided with a central projecting axle 812 and a rotor plug 813 which has an oblong cross section and is configured to fit into the recess 47 in the rotor 41. In use, the first clutch 81 is axially moveable relative to the rotor 41 by a distance less than the depth On the axial direction) of the rotor plug 813, thereby ensuring that the rotor 41 and first clutch 81 are rotationally locked i.e. they cannot rotate relative to each other. The second clutch 82 also has a central projecting axle 822 which fits within a central recess 814 in the rear of the first clutch 81. Since there is no plug portion on the second clutch 82, it is freely rotatable relative to the first clutch 81.

The cam 5 is shown axially in Figure 6. The cam 5 has a cam arm 51 extending from the outer surface and a cam aperture 52 extending through the centre. The cam arm 51 actuates further locking mechanisms in which the lock 1 would be installed in the conventional manner through rotation of the cam 5. In the cam aperture 52 is a pair of cam teeth 53 for engaging the corresponding clutch recesses 811, 821 in the first and second clutches 81, 82 to rotationally engage the cam 5 with one of the clutches 81, 82.

The thumb turn 7 has an elongate shaft 72 with a handle 71 at the end thereof. A thumb turn groove 73 is provided around the shaft 71 and configured to be located within the barrel opening 70 in the second lock housing 3. When assembled, a thumb turn securing pin 74 extends through the thumb turn aperture 25 (see Figure 2) on the second lock housing 3 and sits within the annular thumb turn groove 73. A thumb turn aperture 25 is provided on each of the first and second lock housings 2, 3, although is only used to receive a thumb turn securing pin 74 in the side of the lock 1 which is provided with a thumb turn. The thumb turn 7 further has a clutch spring 83, which extends around the shaft 72 within the barrel opening 70. The clutch spring 83 bears upon a shoulder formed between the shaft 72 and thumb turn groove 73 at a first end thereof, and upon the second clutch 82 at the other end thereof, thereby biasing the second clutch 82 in the direction of the first lock housing 2 (i.e. to the left in Figure 3).

The end of the shaft 72 is provided with a slot 723 which receives a plate 823 extending from the rear of the second clutch 82. The thumb turn 7 and the second clutch 82 are thus rotationally locked together via the plate 823 and slot 723.

With additional reference to Figures 7 to 9, the security mechanism will be described.

The security mechanism has a locking portion 9 which is located within the cam housing 4 in a locking portion bore 91. The locking portion bore 91 extends through the cam housing 4 and opens into the cam ring 45 provided with the rotor 41 at a first end and on the lower surface of the cam housing 4 at the other end. The cam housing 4 further has a lateral opening 92 which extends perpendicularly therethrough and opens into the locking portion bore 91. The lateral opening 92 is continuous with a shallow lateral recess 93 in the surface of cam housing 4. A housing groove 94, 95 is provided on each side of the cam housing 4 facing the first and second lock housings 2, 3, which each have corresponding retainers 26, 36 which fit into the housing grooves 94, 95 when the lock is assembled. The locking portion bore 91 partially passes through the housing groove 94, such that the retainer 26 extends into the locking portion bore 91.

The locking portion 9 is broadly pin shaped, and comprises a bolt head 95 having a bolt portion 96. The bolt potion 96 has an approximately oblong cross section, but wherein the short surfaces are curved. From the bolt head 95 is a bolt shaft 97 located within a torsion spring 971. The lower end of the bolt shaft 97 9 is provided with a plug 98 to secure the locking portion 9 within the locking portion bore 91 in use. The spring arm 99 is made from a resilient material and pre-tensioned against the bolt head 95. The spring arm 99 has a mounting portion 991 having an opening therein for securing with a pin or screw into the lateral recess 93 in the cam housing 4. The spring arm 99 has an arm 992 which extends approximately perpendicularly to the mounting portion 991 and terminates with a spring tooth 993. The bolt head 95 is further provided with a series of recesses therein: a spring recess 952 provides a shoulder against which an end of the torsion spring can bear, a housing recess 951 which receives the retainer 26 in use, and a socket 953 for receiving the spring tooth 993.

Figures 9a and 9b show the locking portion in a first condition (primed) and second condition (locked) respectively. In Figure 9a, the spring tooth 993 bears against the surface of the bolt head 95, and is offset from the socket 953 by 90°. The bolt portion 96 is aligned parallel with the tooth. In 9h, the bolt head 95 has been rotated through 90° such that the socket 953 is aligned with and receives the tooth of the pre-tensioned spring arm 99. In the first condition, the rotor 41 would be free to rotate, and in the second condition, both the bolt head 95 and the rotor 41 would be unable to rotate.

The operation of the lock 1 will now be described with additional reference to Figure 10. Figure 10 shows the lock 1 in the configuration wherein a key 10 has been inserted into the barrel 6. The lock pins 61 have been depressed such that the barrel 6 is rotatable within the lock housing 2 by rotating the key 10. The rotor 41 is rotationally locked to the barrel 6 as described above. The leading tip of the key 10 extends into the central aperture 46 in the rotor 41 and bears upon the leading face of the projecting axle 812 of the first clutch 81. The key 10 thus pushes the first and second clutches against the bias of the clutch spring 83 On the direction of the dashed arrow). This axial movement of the first and second clutches 81, 82 engages the first clutch 81 with the cam 5 by engaging the cam teeth 53 with the clutch recesses 811 of the first clutch 81. Simultaneously, the second clutch 82 is pushed out of engagement with the cam 5.

The locking portion 9 is located within the locking portion bore 91 such that the bolt head 96 extends into the circumferential groove 411 in the rotor 41. The bolt portion 95 is oriented such that length of the bolt head 96 is aligned with the circumferential groove 411 and the bolt head 96 does not extend into the locking recess 48. The bolt portion 95 is maintained in this orientation by the retainer 26 of the first lock housing 2 which is located within the housing groove 94 and into the housing recess 951 of the bolt portion 95. The bolt portion 95 is thus prevented from rotating under the biasing force of the torsion spring 971. The rotor 41 is thus free to rotate, and thus the user is able to actuate the cam 5 (via the barrel 6, rotor 41, and first clutch 81) by rotating the key 10. The locking mechanism in which the lock 1 is installed can thus be operated.

When a user removes the key 10 (not shown), the clutch spring 83 biases the first and second clutches 81, 82 in the opposite direction to the dashed arrow. The resting position of the first and second clutches 81, 82 are as shown in Figure 11, wherein the first clutch 81 is disengaged from the cam 5. Thus in a default condition (i.e. without a key) there is no path to transmit a force to the cam from the external side of the lock. In such a condition, the cam 5 can always be actuated by rotating the thumb turn 7 from the inside of the lock 1, since the second clutch 82 connects the thumb turn 7 to the cam 5.

Turning now to Figure 11, the anti-snapping properties of the lock 1 will be described.

Lock snapping is a method of attack whereby an attacker grips the exposed end of the lock 1 with a tool such as pliers and violent twists or jerks the lock to snap the lock in half through the weak point where the central screw hole passes through the cam housing. Figure 11 models the condition of the lock 1 once an attacker has performed a 'lock snapping' attack. As also shown in Figure 3, the first lock housing 2 is mounted on a peg 44 extending from the cam housing 4 by securing pins 22. This forms a frangible region which will break preferentially upon application of a strong force to the exposed end of the lock 1 (although the peg 44 is shown as intact in Figure 11 for ease of reference). This prevents the lock from being snapped in half through the middle of the cam housing 4. This is shown in Figure 11 by the first lock housing 2 being separated from the cam housing 4.

Critically, upon snapping of the lock 1, the lock 1 enters a second condition. The removal of the first lock housing 2 means that the retainer 26 is withdrawn from the housing groove 94 on the cam housing 4. The retainer 26, which bears upon the housing recess 951 of the locking portion 9 in its default condition, is no longer able to interact with the locking portion 9. The torsion spring 971 is pre-stressed such that it applies a biasing force upon the bolt portion 95. As soon as the retainer 26 is disengaged from the housing recess 951, the torsion spring 971 rotates the bolt portion 95. Once the bolt portion 95 has rotated through 90°, the socket 953 is aligned with the spring arm 99. Since the spring arm 99 is also pre-stressed during assembly, once the socket 953 is aligned, the spring arm 99 fires the tooth 993 into the socket 953 to prevent further rotation of the bolt portion 95. This rotation and firing of the spring arm 99 is shown in Figures 9a and 9b. In this condition, the bolt portion 95 is rotationally locked with the bolt head 96 extending perpendicularly to the circumferential groove 411 and into the locking recess 48. The ends of the bolt head 96 thus butt against the shoulder 49 of the locking recess 48 and thus prevent rotation of the rotor 41.

In this second condition, the rotor 41 is exposed to an attacker, but is unable to rotate in order to actuate the cam 5. The projecting axle 812 of the first clutch 81 is exposed and can be pushed by an attacker to engage the cam 5, but due to the rotor plug 813 still being received within the recess 47 in the rotor 41, the first clutch 81 is also unable to rotate. Thus, in the second condition, it is not possible to operate the lock 1 from the external side, but the lock 1 can still be operated from the internal side by actuating the thumb turn 7.

Turning now to Figure 12, there is shown a further embodiment of a cylinder lock 100, having a first lock housing 102 and a second lock housing 103, on either side of a cam housing 104 and cam 105. Description of components and features shared with the first embodiment will not be repeated. The security mechanism from the first embodiment is present but not shown in Figure 12.

The clutch mechanism has a first rotor 141 and a first and second clutch. The first clutch is formed from a pressure plate 181a, drive plate 181b, first clutch drive spring 181c positioned therebetween and a pusher 181d. The first rotor 141 is located within a cam ring 145 on the cam housing 104 as described previously, with the pusher located within a slot in end of the first barrel (not shown). The second clutch has a second rotor 182a, a drive connector 182b, and a second clutch spring 182c. The second rotor 182a is located within the end of the second lock housing 103 and secured with a circlip (not shown) and is rotationally locked to the cam by way of recesses 182a' which receive projections (not shown) on the cam 104. The drive connector 182b extends through the second rotor 182a and comprises a pair of teeth 181b' which fit within a slot (not shown) in the second rotor and the second barrel (not shown).

A clutch pin 184 extends between the first and second clutches and has a screw threaded portion 184b which engages a cooperating threaded region within the projecting axle 1812 of the pressure plate 181a. The opposite end of the clutch pin 184 is received within a socket in the drive connector 181b. Between the ends of the clutch pin 184 is a drive plate surface 184a which extends perpendicularly to the shaft of the pin 184. A clutch default spring 183 is located between and bears against the drive plate surface 184a and the second rotor 182a.

In use, a user inserts a key into the first, external side, lock barrel. The tip of the key pushes on the pusher 181d which extends through the first rotor 141 and pushes on the projecting axle 1812 of the pressure plate 181a. The pressure plate presses the drive plate 181b toward the cam 141 until the interlocking formation (tooth 181b') of the drive plate 181b engages a cooperating formation (a recess, not shown) within the cam 104. The interlocking formation 181b' thus extends between the cooperating formation 181a' on the pressure plate 181a and the cam 104, rotationally locking them together.

The clutch pin 184 is also pressed forwards through the cam 104 whereby the tip pushes the drive connector 181b toward the second barrel such that only the cylindrical shaft of the drive connector is located within the second rotor 182a and thus the second rotor is able to rotate relative to the drive connector 181b and the second lock barrel (not shown). Thus, as a user rotates the key, the rotor 141, first clutch, cam 104, and second rotor 182a all rotate together. If the cam 104 is misaligned, the drive plate 181b is compressed against the first clutch drive spring 181c between the cam 104 and pressure plate 181a. As the user rotates the first barrel, the first rotor 141, pressure plate 181a, and drive plate 181b all rotate together. Once the cam 104 and drive plate 181b are aligned, the first clutch drive spring 181c biases the drive plate 181b into further engagement with the cam 104, whereby and the cam 104 can be actuated as normal.

When a user inserts a key into the second, internal side, lock barrel within second lock housing 103, the process is reversed. The drive connector 181b is pushed toward the cam 104, whereby the teeth 181b' engage a slot in the second rotor 182a. The second barrel is thus rotationally locked to the cam 104. The drive connector 181b pushes the clutch pin 184 toward the external side, whereby the drive plate surface 184a presses against the drive plate 181b to ensure the first clutch is disengaged from the cam 104.

The cam 104 is thus rotationally locked with the second barrel and the lock can be actuated by the key.

The clutch mechanism of the second embodiment thus compensates for the cam 104 being misaligned with the external side, first barrel and first clutch. In embodiments wherein the internal side of the lock is provided with a key operated lock barrel, the key cannot be removed unless the lock barrel is returned to a default position because of the locking pins within the barrel and second lock housing. However, in embodiments wherein the internal side of the lock cylinder comprises a thumb turn, it is common for the internal side (and thus the cam) to not be returned to the default position. The above clutch mechanism thus provides a lost motion' mechanism whereby a key can be inserted into the external barrel and rotation thereof will engage the cam once aligned by rotation of the key, barrel and clutch mechanism.

Claims

CLAIMS: 1. A cylinder lock comprising: a lock barrel; a cam; a clutch mechanism configured to connect the lock barrel and the cam upon insertion of a key into the lock barrel, the clutch mechanism comprising a rotor configured to transfer a rotation from the lock barrel to the cam; and a security mechanism comprising a locking portion configured such that the locking portion is rotatable between: a first condition wherein the rotor is rotatable, and a second condition wherein the locking portion blocks the rotor from rotating.
2. The cylinder lock according to claim 1, wherein the lock barrel is provided in a first lock housing and the cam is provided in a cam housing, and wherein the cylinder lock comprises a frangible portion or connection between the first lock housing and the cam housing.
3. The cylinder lock according to claim 2, wherein the cylinder lock is configured such that the second condition is caused by the first lock housing being removed and/or disconnected from the cylinder lock.
4. The cylinder lock according to claim 2 or claim 3, wherein the first lock housing comprises a retainer configured to retain the locking portion in the first condition.
5. The cylinder lock according to claim 4, wherein the locking portion comprises a contact surface or recess configured to engage the retainer when in the first condition.
The cylinder lock according to any one of the preceding claims, wherein the security mechanism comprises a biasing mechanism configured to rotate the locking portion into the second condition.
The cylinder lock according to any one of the preceding claims, wherein the rotor comprises a recess and the locking portion comprises a bolt, configured such that the bolt engages the recess when in the second condition.
The cylinder lock according to any one of the preceding claims, wherein the rotor comprises a circumferential groove and wherein a portion of the locking portion is received within the circumferential groove.
9. The cylinder lock according to claims 7 and 8, wherein the recess is provided in or contiguous with the circumferential groove.
10. The cylinder lock according to any one of claims 7 to 9, wherein the bolt portion comprises a bolt head which, when rotated into the second condition, engages at least one shoulder of the recess.
11. The cylinder lock according to any one of the preceding claims, wherein the locking portion comprises a restrictor mechanism configured to prevent the locking portion from returning to the first condition once in the second condition.
12. The cylinder lock according to any one of the preceding claims, wherein the locking portion has an axis of rotation which is perpendicular to the axis of rotation of the rotor.
13. The cylinder lock according to any one of the preceding claims, wherein the clutch mechanism comprises at least one clutch which is axially moveable to engage and disengage the cam.
14. The cylinder lock according to claim 13, comprising a first and second clutch, and wherein the clutch mechanism is configured such that inserting a key into the barrel moves the first clutch into engagement with the cam and/or moves the second clutch out of engagement with the cam.
15. The cylinder lock according to claim 13 or 14, wherein the at least one clutch is rotationally locked with the rotor.