The present invention is concerned with a lock mechanism. More particularly, the present invention is concerned with a security cylinder lock mechanism.

Cylinder locks generally comprise a lock mechanism having a first lock actuator, a second lock actuator and a rotatable cam disposed therebetween. The lock actuators are actuable either by the use of a key or a thumb bolt to selectively rotate the cam. The cam generally comprises a cam shaft and a cam lever projecting therefrom.

A clutch mechanism within the lock mechanism is actuable to selectively engage one or the other of the first and second lock actuators. This is because the rotation of key actuable lock actuators is inhibited when a key is not inserted. Therefore, for example, if a lock mechanism comprises two key lock actuators, insertion of the key into the first lock actuator will automatically disengage the load path between the second lock actuator and the cam such that the cam can be rotated by the first lock actuator. Alternatively, insertion of a key into the second lock actuator will move the clutch such that a load path is formed between the second lock actuator and the cam. In use, the cylinder lock is installed in a lock casing containing a mechanism for shooting a lock bolt. The cam is enclosed within front and rear walls of the casing. When the cam is rotated the cam lever engages the lock bolt mechanism to extend and retract the lock bolt to lock and unlock a closure. Cylinder locks of this type are susceptible to unauthorised actuation. Unauthorised actuation may be attempted by removal of the closest (usually exterior) lock actuator and manual rotation of the cam to actuate the lock bolt mechanism. Alternatively, the cam is removed and the lock bolt is manually retracted within the lock casing with a suitable tool.

This problem is exacerbated when a thumb bolt actuator is installed on the interior side of the closure rather than a key actuator. The cam can be freely rotated when engaged with the thumb bolt actuator because the thumb bolt does not require insertion of a key in order to rotate it.

It is an aim of the invention to provide an improved cylinder lock.

According to a first aspect of the invention there is provided a cylinder lock comprising a first lock actuator rotatable within a first lock actuator housing, a second lock actuator, a lock cam having a cam shaft and a cam lever projecting therefrom, the lock cam disposed between the first and second lock actuators and rotatable about a lock axis, a clutch mechanism configured to selectively form a drive path between either of the first and second actuators and the lock cam, in which the clutch mechanism has a security position in which it is directly engaged with both the cam and the first actuator such that the cam is constrained relative to the first actuator. Advantageously, constraint of the cam shaft relative to the first lock actuator makes it harder for the cam both to be displaced once the second lock actuator has been removed and, furthermore, inhibits rotation of the cam off its axis.

According to a second aspect of the invention there is provided a lock mechanism comprising a first lock actuator, a second lock actuator, a lock cam having a cam shaft and a cam lever projecting therefrom, the lock cam disposed between the first and second lock actuators and rotatable about a lock axis and a blocking member at least partially covering the cam lever in a direction parallel to the lock axis. Advantageously, the blocking member will make access to the lock cam more difficult when the exterior lock actuator is removed from the cylinder lock. Therefore, it becomes more difficult to manually force rotation of the lock cam to unlock the lock. It is also more difficult to remove the cam from the mechanism. Preferably the cylinder lock comprises a predetermined weakened area on the opposite side of the blocking member to the cam lever. In this way, when the lock is subjected to high forces, it will break at the predetermined position leaving the blocking member intact and preventing access to the cam lever. Preferably, a connecting member is provided connecting the first and second lock actuators, the blocking member defined on the connecting member. Preferably the connecting member comprises an attachment formation for attachment of the cylinder lock to a lock housing.

Preferably the weakened area is defined on the connecting member. In this way, the weakened area is put in the "critical" load path of the lock, and manipulation of the actuator will tend to break the connecting member at the desired position.

Preferably the weakened area is a groove formed in the outer surface of the connecting member.

Preferably the weakened area is defined between the blocking member and a first attachment formation for attachment of the connecting member to the first or second actuator.

According to a third aspect of the invention there is provided a lock assembly comprising a lock cylinder having a first lock actuator, a second lock actuator, and a lock cam having a cam shaft and a cam lever projecting therefrom, the lock cam disposed between the first and second lock actuators and rotatable about a lock axis, a lock casing having a first wall and a second wall in which the lock cylinder is mounted in the lock casing such that the cam lever is between the first and second wall and such that the cam shaft projects axially from the first wall.

Advantageously, projection of the cam shaft from the casing inhibits rotation of the cam shaft off its axis, and inhibits access to the lock interior.

Preferably the lock cylinder is mounted in a lock casing such that the cam lever is between a first and second wall and such that the cam shaft projects axially from the first wall. Preferably the blocking member projects from the first wall. In this way, when the lock is broken, the combined projection of the blocking member and the cam shaft will fill the entire cylinder orifice making it very difficult to manipulate the lock. Preferably the cam shaft and the blocking member project to approximately the same position. Preferably the axial end faces of the cam shaft and the blocking member are flush. Preferably the cam shaft projects axially from the second wall.

According to a fourth aspect of the invention there is provided a cylinder lock comprising a first lock actuator, a second lock actuator, a lock cam having a cam shaft and a cam lever projecting therefrom, the lock cam disposed between the first and second lock actuators and rotatable about a lock axis, wherein the cam shaft defines a retention member extending radially outwardly therefrom for axial constraint of the cam shaft against a bearing surface.

Advantageously, the provision of a retention member such as a flange extending from the cam shaft prevents axial movement and rotation of the cam once it has been accessed by removal of one of the lock actuators. The retention member will typically engage an external surface of the lock casing on an interior side of the closure. Alternatively, the flange could abut an external side of the lock casing on the exterior side of the closure, thus inhibiting access to the inside of the lock casing by tools.

It will be noted that the third anf fourth aspects of the invention are alternative solutions to the same problem- that is breaking of the lock and access to the casing interior by rotation of the cam off its axis.

According to a fifth aspect of the invention there is provided a thumb bolt mechanism for a cylinder lock comprising a housing, a barrel mounted within the housing, a thumb bolt connected to the housing and the barrel such that in a first condition of the mechanism the barrel is rotationally fixed relative to the housing and in a second condition of the mechanism the barrel is rotationally movable relative to the housing about a main axis upon application of a torque to the thumb bolt, in which the thumb bolt is axially movable to move the mechanism from the first condition to the second condition.

The user is thereby required to push (or optionally pull) the thumb bolt before turning. Advantageously, the provision of a push activated thumb bolt prevents unauthorised rotation of the cam from the exterior side of the lock once an exterior actuator is removed. Therefore, a cylinder lock which utilises a thumb bolt on the interior side is made more secure. The thumb bolt mechanism according to the fifth aspect is installed into a cylinder lock comprising,

a first lock actuator rotatable with a first lock actuator housing,

a lock cam having a cam shaft and a cam lever projecting therefrom, the lock cam disposed between the first lock actuator and the thumb bolt mechanism and rotatable about a lock axis,

a clutch mechanism configured to selectively form a drive path between the lock cam and either of (i) the first actuator and (ii) the barrel.

Preferably the clutch mechanism has a security condition in which it is immovably engaged with the barrel.

Preferably the clutch mechanism is configured to move into the security position upon removal of a component of the cylinder lock, preferably the first lock actuator. In this way, if an attempted entry is made by breaking the cylinder, the clutch will advance to the security condition where it is engaged with the barrel, and assuming the thumb bolt is in the first condition, the clutch (and therefore cam) will be non- rotatably fixed in position, preventing manual manipulation of the lock. After the event, the rightful user can manipulate the thumb bolt to the second condition to open the lock from the interior after gaining access via an alternative route. According to a sixth aspect of the invention there is provided a cylinder lock comprising a lock housing and a lock barrel rotatably mounted within the lock housing, wherein the lock barrel defines a radially extending surface engaged by a fastening element projecting radially inwardly within the lock housing.

Advantageously, the provision of such an arrangement increases security over, for example, a circlip retaining the lock barrel. This arrangement takes up less space compared to a circlip-fastened arrangement so the lock cam can be made longer, thus decreasing its ability to rotate off its axis within the lock casing. Furthermore, the groove for receiving the fastening element on which the radially extending surface is defined can be positioned within the lock actuator housing. This differs from the circlip arrangement in which the circlip groove must be placed just outside the housing. These grooves act as stress raisers in the lock barrel, and as such by positioning the groove within the housing it is less susceptible to damage from external forces. Therefore the cylinder lock is made more secure.

Preferably the fastening element is a pin extending through a wall of the lock housing.

Preferably a further fastening element is provided projecting radially inwardly within the lock housing at a different circumferential position. Preferably three such fastening elements are provided being equally circumferentially spaced.

Various exemplary embodiments of security lock cylinders in accordance with one or more aspects of the present invention will now be described in detail with reference to the accompanying drawings in which:

FIGURE 1 is an exploded perspective view of a first lock cylinder assembly in accordance with the present invention;

FIGURE 2 is a side view of the lock cylinder assembly of Figure 1;

FIGURE 3 is a perspective view of a part of the lock cylinder assembly of Figure 1 installed within a lock casing; FIGURE 4 is an exploded perspective view of a second lock mechanism in accordance with the present invention; FIGURE 5 is a schematic side section view of the lock mechanism of Figure 4;

FIGURE 6A is an exploded perspective view of a third lock mechanism in accordance with the present invention, and, FIGURE 6B is an exploded perspective view of a part of the lock mechanism of figure 6A.

Referring to Figure 1, a lock mechanism 100 comprises a first lock actuator 102, a second lock actuator 104, a cam 106 and a clutch assembly comprising a first clutch sub-assembly 108 and a second clutch sub-assembly 110. The lock mechanism 100 further comprises a retention member 112.

The first lock actuator 102 comprises a first lock actuator housing 114 and a first lock barrel 116. The first lock actuator housing 114 comprises a hollow cylinder 118 with a lug 120 projecting radially therefrom. The cylinder 118 defines two radially extending through-bores 119. The lug 120 defines a blind bore 122 extending partially therethrough parallel to the cylinder 118. The lug 120 further defines a pair of cross bores 124. The first lock barrel 116 comprises a pin tumbler mechanism suitable for the receipt of a key. The first lock barrel 116 is rotatable within the first lock actuator housing 114 upon insertion of an appropriate key. When a key is not inserted into the first lock barrel 116, the barrel cannot rotate relative to the first lock actuator housing 114. The operation of such locks is well known in the art and as such will not be disclosed here.

The first lock barrel 116 defines a circumferential groove 126, an axially extending key slot 130, a first clutch slot 132 and a second, opposing, clutch slot 134, both extending axially from an end of the first lock barrel 116. The first lock barrel 116 also defines a radially extending lock pin orifice 131.

The second lock actuator 104 comprises a second lock actuator housing 136 and a second lock barrel 138. The second lock actuator housing 136 is substantially similar to the first lock actuator housing comprising a cylinder 140 and a lug 142 extending radially therefrom. The lug 142 defines a blind bore 144 and a pair of cross bores 146. The second lock barrel 138 is also rotatable within the second lock actuator housing 136 upon receipt of a key into a key slot 148. The second lock barrel 138 defines a circumferential circlip groove 150 which protrudes from the cylinder 140 of the second lock actuator housing 136 when the second lock barrel 138 is situated within the second lock actuator housing 136.

The first clutch sub-assembly 108 comprises a compression spring 152 and a first clutch component 154. The first clutch component 154 comprises a stepped shaft 156 with a drive member 158 radially extending from the larger diameter portion thereof. The first clutch component 154 further comprises a cylindrical toughened steel insert 160 installed within an axial bore thereof. Finally, the first clutch component 154 comprises a radially moveable lock pin 162 radially outwardly biased by a compression spring 164.

The second clutch assembly 110 comprises a second clutch component 166 comprising a stepped shaft and having a drive member 168 extending radially therefrom. The second clutch assembly 110 further comprises a push pin 170 mounted axially to abut the larger diameter portion of the second clutch component 166. The cam 106 comprises a generally cylindrical cam shaft 172 having a cam lever 174 projecting radially therefrom. The cam lever 174 generally tapers to become wider as it extends away from the cam shaft 172. The cam shaft 172 is generally hollow with the exception of a centre wall 176 having a bore 178 defined axially therethrough. The centre wall 176 is profiled to engage the drive member 158 of the first clutch component 154 on one side or the drive member 168 of the second clutch component 166 on the opposite side.

The cam shaft 172 defines a radial lock pin bore 173 extending through its outer wall.

The retention member, or shackle, 1 12 comprises a body 180 having a first shaft 182 extending axially therefrom and a second shaft 184 extending axially therefrom in an opposite direction. Each of the first and second shafts 182, 184 comprise two pin holes 186, 188 respectively. The body 180 is generally cylindrical having opposing flats 190 at its top and bottom surfaces and comprising a blocking element 192 extending therefrom. The blocking element defines a concave part-cylindrical surface 194. The body 180 defines a transverse mounting bore 181 therethrough for attachment to a lock casing. The retention member 112 is a unitary body.

A circumferential groove 113 is provided on the second shaft 184 between the blocking element 192 and a free end of the shaft 184. The groove 113 is positioned between the blocking element 192 and the first point at which the retention member is fixed to the lock casing at the first of the holes 188 (as will be described below). The groove 113 provides a predetermined weakened area which ensures that if the second lock actuator 104 is forcibly removed, the retention member will break at the groove

113 thus leaving the retention member intact. It will be noted that the groove is not directly adjacent the blocking element 192 to avoid breaking too close to this component and propagating any cracks into it.

The lock mechanism 100 is assembled as follows:

Lock barrels 116, 138 are inserted into their respective lock actuator housings 114, 136. The first lock barrel 116 is axially retained with the first lock actuator housing

114 by passing retention pins through the pin holes 119 to engage the circumferential groove 126 on the lock barrel 116. The second lock barrel 138 is retained within the second lock actuator housing 136 a circlip into the circuit groove 150. The compression spring 152 engaged to bear on the first lock barrel 116 and the first clutch component 154 is engaged with the first lock barrel 116 such that the drive member 158 engages the second clutch slot 134. At the same time the hardened steel insert 160 is mounted within the step shaft 156. The lock pin 162 is resilient ly mounted within the stepped shaft 156 against the bias of the compression spring 164.

The cam 106 is placed over the first clutch component 154 and the smaller diameter shaft of second clutch component 166 is inserted through the through-bore 178 of the cam centre wall 176 to abut the first clutch sub-assembly 108. The clutch components 166 can move axially against the resilience of the compression spring 152.

The push pin 170 is abutted against the second clutch component 166 and the second lock barrel 138 is brought to bear against the push pin 170. The first lock actuator housing 114 and the second lock actuator housing 136 are joined with the retention member 112. The first shaft 182 is engaged with the blind bore 112 of the first lock actuator housing 114 and the second shaft 184 is engaged with the blind bore 144 of the second lock actuator housing 136. A set of retention pins 196 are passed into the cross bores 124, 146 and engage with the pin holes 186, 188 of the retention member to hold the mechanism together.

It will be understood that in use, the clutch assembly is moveable such that the first clutch component 154 and the second clutch component 166 can move axially to be selectively engageable with the cam 106. The compression spring 152 urges the clutch components 154, 166 towards the second lock actuator 104. In this way, the drive member 158 engages the centre wall 176 of the cam 106. Therefore, upon insertion of a key into the first lock barrel 116, rotation thereof causes rotation of the first clutch component by virtue of engagement between the drive member 158 and the second clutch slot 134. This in turn causes rotation of the cam 106 due to the engagement of the drive member 158 with an appropriate groove machined into the centre wall 176 (not shown). On the other hand, if a key is inserted into the second lock barrel 138, a load path is created through the push pin 170 to the second clutch component 166 to push the first clutch component 154 out of engagement with the cam 106 and to engage the drive member 168 with a groove on the centre wall 176 of the cam 106.

In this way, if a key is inserted from the inside of the closure where the first lock actuator resides, then this key can be rotated to turn the cam 106 and consequently lock or unlock any lock bolt as the cam lever 174 turns. Alternatively, if the user is on the exterior of the closure, a key can be inserted into the key slot 148 of the second lock barrel 138 which actuates the clutch components 154, 166 such that the drive member 168 engages the cam 106 and the door can be unlocked from the outside.

It will be understood that if the second lock barrel 138 is removed with or without the second lock actuator housing 136, the push pin 170 and the second clutch component 166 fall away. This allows the compression spring 152 to push the first clutch component 154 into an over-travel position at which point the lock pin 162 extends under the bias of the spring 164 and engages the lock pin orifice 131 on the first lock barrel 116 to lock the clutch. The lock pin 162 also extends through the lock pin orifice 131 to engage the lock pin bore 173 on the cam shaft 172. In this way the cam 106 is now constrained relative to the first lock barrel 116 making movement or removal of the cam 106 more difficult. Consequently the cam is engaged with the first lock barrel 116. As such, a person trying to infiltrate the lock mechanism from the exterior would not be able to turn the cam 106 as it will be keyed to the first lock actuator 116 which cannot be rotated without insertion of a key from the interior.

In use, and as shown in Figure 2, additional security is provided by the existence of the blocking element 192 which extends all the way to the cam shaft 172. As mentioned, the blocking element 192 defines a concave cylindrical surface 194 which abuts and bears on the cylindrical surface of the cam shaft 172. As such, an additional security measure is provided by the fact that once the second lock barrel 138 and the second lock actuator housing 136 is removed, a person attempting to break- in cannot access the cam lever 174 to rotate it because the blocking member 192 obstructs access to that component. It will be noted that the range of motion of the cam lever 174 in use is only 10-15 degrees from its nominal position and, as such, the blocking member 192 will block at least part of the cam 174 for all positions in its normal range of movement. This makes it extremely difficult for a person to access the cam lever 174 and rotate or remove the cam 106.

Referring now to Figure 3, the lock assembly 100 is shown installed within a lock casing 10 having a cylinder lock receiving bore 12. The cam 106 is rotatable within the lock casing 10. As can be seen, if the second lock actuator 104 is removed (in this instance the second shaft 184 has been broken at the groove 113 to enable this removal), the cam shaft 172 projects from the lock casing 10. Furthermore, the body 180 and the blocking element 192 both project from the lock casing 10 to prevent any access to the cam lever 174 within the lock casing 10. As such, there is no gap or clearance into which a tool can be forced to gain access. A tight fit with the euro- profile orifice of the lock casing ensures that manipulation of the cylinder lock is made more difficult.

When the lock mechanism 100 is in the locked condition, the cam lever 174 is misaligned with the bore 12. The cam 106 therefore cannot be removed axially without rotation to the unlocked condition. Such rotation is not possible because, as mentioned, the cam is now keyed to the first lock actuator 102 which cannot be accessed unless a key is inserted from the inside.

Referring to Figure 4, a second lock mechanism 200 is shown. The second lock mechanism 200 is similar to the first lock mechanism 100 and similar components will have reference numerals 100 greater.

The cam 206 is identical to the cam 106 with the exception that flanges 302, 303 project radially therefrom at the first lock actuator end. Turning to Figure 5, the lock mechanism 200 is shown installed within a lock casing 10 having a lock mechanism bore 12. The lock casing 10 has an exterior side 14 and an interior side 16. As can be seen, the first lock actuator 202 is installed on the interior side 16 and the second lock actuator 204 is installed on the exterior side 14. The flanges 302, 303 of the cam 206 abut the external side of the lock casing 10 at the interior side 16. As such, if the second lock actuator 204 is removed, then the cam 206 cannot easily be rotated or removed due to the abutment of the flanges 302, 303 with the lock casing 10.

The flanges 302, 303 are diametrically opposed and the flange 303 is aligned with the cam lever 274. This makes installation of the cylinder lock mechanism 200 into the lock casing 10 easier. The flange 303 will only abut the lock casing 10 when the mechanism 200 is in the locked condition.

Referring to figures 6A and 6B, a lock mechanism 400 is shown. The lock mechanism 400 comprises a first lock actuator 402, a second lock actuator 404, a cam 406 and a clutch assembly comprising a first clutch sub-assembly 408 and a second clutch sub-assembly 410. The lock mechanism 400 further comprises a retention member 412.

The first lock actuator 402 comprises a first lock actuator housing 414 and a first lock barrel 416. The first lock actuator housing 414 comprises a hollow cylinder 418 with a lug 420 projecting radially therefrom. The cylinder 418 defines two radially extending through-bores 419. The lug 420 defines a blind bore 422 extending partially therethrough parallel to the cylinder 418. The lug 420 further defines a pair of cross bores 424.

The first lock barrel 416 defines a circumferential groove 426 and an axially extending key slot 430. The first lock barrel 416 further defines an axially extending pin slot 431.

The first lock barrel 416 comprises a pin tumbler mechanism suitable for the receipt of a key. A key is not provided with the first lock barrel 416. Instead, a thumb-turn assembly 500 is provided.

The thumb-turn assembly 500 comprises a thumb-bolt 502 having a lever 504 connected to a first shaft 506 which steps down into a second shaft 508 at a shoulder 509. The second shaft 508 defines a slot 510 and has a pin bore 512 defined transverse thereto. The thumb turn assembly 500 further comprises a key element 514 capable of engaging with the barrel 416 in order to rotate the barrel relative to the housing 414. The key element 514 must be fully inserted into the barrel 416 to rotate it, if the key element 514 is not fully inserted into the barrel 416, the barrel 416 is locked for rotation relative to the housing 414.

The key element defines a rearward-facing shoulder 515. The second lock actuator 404 comprises a second lock actuator housing 436 and a second lock barrel 438. The second lock actuator 404 is substantially similar to the second lock actuator 104 of the lock mechanism 100 and as such will not be described in detail here. The first clutch sub-assembly 408 comprises a compression spring 452 and a first clutch component 454. The first clutch component 454 defines a drive member 458 radially extending therefrom. Finally, the first clutch component 454 comprises a radially moveable lock pin 462 radially outwardly biased by a compression spring 464.

The second clutch assembly 410 comprises a second clutch component 466 comprising a stepped shaft and having a drive member 468 extending radially therefrom. The cam 406 comprises a generally cylindrical cam shaft 472 having a cam lever 474 projecting radially therefrom. The cam lever 474 generally tapers to become wider as it extends away from the cam shaft 472.

The cam shaft 472 is generally hollow with the exception of a centre wall (not visible) having a bore defined axially therethrough. The centre wall is profiled to engage the drive member 458 of the first clutch component 454 on one side or the drive member 468 of the second clutch component 466 on the opposite side. The cam shaft 472 defines a radial lock pin bore 473 extending through its outer wall.

The retention member 412 comprises a body 480 having a first shaft 482 extending axially therefrom and a second shaft 484 extending axially therefrom in an opposite direction. Each of the first and second shafts 482,484 comprise two pin holes respectively. A blocking element 492 is slidable over the second shaft 484 to project radially from the shaft 484 proximate the body 480. It is secured with a pin or rivet 481. The blocking element 492 defines a concave part-cylindrical surface 494. The body 480 defines a transverse mounting bore therethrough for attachment to a lock casing.

The lock mechanism 500 is assembled and operates in a similar manner to the lock mechanism 100, with the following exceptions. The thumb-turn assembly 500 is assembled by placing a compression spring 516 over the shaft 508 to abut the shoulder 509. The key element 514 is placed through the spring 516 into the slot 510. The shoulder 509 abuts the spring 516. The thumb bolt assembly 500 is then inserted into the barrel 516 and secured with a slide pin 518 which retains the key element 514 relative to the shaft 508. The slide pin 518 is slidable in the pin slot 431. The spring 516 abuts a surface (not visible) within the barrel 416 such that the thumb bolt 502 is biased away from the barrel 416.

Finally, the barrel 416 is secured within the casing 414 using a pair of pins 520 which penetrate the bores 419 to engage the groove 426. Therefore the barrel 416 is constrained axially, but able to rotate when the key element 514 is fully inserted.

The key element 514 can only be fully inserted by pushing the thumb bolt 502 towards the lock mechanism 500 against the bias of the spring 516. As such, the lock mechanism is generally locked against rotation until either a key is inserted into the second lock mechanism 404 or the thumb-bolt 502 is pushed in and rotated.

Consequently, if an intruder breaks off the second lock actuator 404, the cam 406 cannot be easily rotated. Firstly, the blocking member 492 will prevent access to the cam lever 474. Secondly, the cam 406 cannot be rotated unless the thumb bolt 502 is depressed, which is not possible from the outside of the closure.

It will be understood that variations of the above embodiments fall within the scope of the present invention.

For example, the thumb bolt may be designed such that is only extends to the locked position at a predetermined rotational position. At all other positions it is retained inwardly against the bias of the spring 516.

In addition, any of the aspects of the present invention may be used in isolation or in combination in order to provide an improved locking arrangement.

In order to increase strength, the various lock components may be constructed from materials such as high tensile steel, kevlar and composites as opposed to the traditional sintered components such as brass.