High security lock cylinder

Abstract

A cylinder lock (single or double cylinder lock) 1 comprises a first lock barrel 6, a cam 5 and a clutch mechanism 5 configured to connect the first lock barrel to the cam when a key is inserted into the barrel. The clutch mechanism comprises a first clutch portion 81 and a second clutch portion 82. In a first condition, the first and second clutch portions (81, 82) are axially movable in unison to engage and disengage the cam 5, preferably by spring 84 and retainer 85 coupling the clutch parts together. In a second condition, such as breaking and removing the barrel 6, the first clutch portion (81) is freely axially movable relative to the second clutch portion (82), such that the clutch mechanism cannot engage the cam 5, preferably by a retainer being removed along with barrel during tampering releasing spring 84 and uncoupling the clutch parts. A spring 87 may bias clutch 81 into the lock housing. A second barrel may be included with a third clutch part 83.

Description

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 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 greater 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 comprises a first lock barrel, a cam, and a clutch mechanism configured to connect the first lock barrel to the cam when a key is inserted into the barrel. The clutch mechanism may comprise a first clutch portion and a second clutch portion. The first and second clutch portions may be configured such that in a first condition, the first and second clutch portions are axially movable together to engage and disengage the cam. The first and second clutch portions may be configured such that in a second condition, the first clutch portion is freely axially movable relative to the second clutch portion, such that the clutch mechanism cannot engage the cam. This is advantageous, since once the lock is in the second condition, any further movement of the first clutch portion has no impact on the position of the second clutch portion. An attacker, having triggered the lock moving into the second condition, is thus unable to actuate the lock using the first and / or second clutch portion. By ‘key’ it is intended that the key is the corresponding key for the first lock barrel. The first lock barrel may be provided with a series of encoded lock pins. The lock pins may prevent rotation of the barrel when the correspondingly encoded key is not present. The key may be configured to move the encoded lock pins in order to permit rotation of the barrel. The first 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 frangible connection between the first lock housing and the cam housing. The frangible connection may comprise a peg extending from the cam housing and a recess on the lock housing or vice versa. In embodiments comprising an integrally formed cam housing and lock first housing, the frangible portion may comprise one or more slots or narrowed portions. The cylinder lock may be configured such that the second condition is caused by the first lock barrel being removed and / or disconnected from the cylinder lock. For example, the second condition may be caused by the lock being snapped. For example, the lock may snap at the frangible portion between the first lock housing and the cam housing, thereby allowing removal of the first lock barrel. The first clutch portion and the second clutch portion may be connectable by a spring in the first condition. The spring may comprise a torsion spring. The spring may comprise a spring arm. The spring may be fixed or fixedly connectable to the second clutch portion. The second clutch portion may comprises a recess for retaining the spring. The first clutch portion may comprise a groove or channel for receiving a portion of the spring in the first condition. The groove or channel may be annular. The groove or channel may be configured to allow rotation of the first clutch portion relative to the second clutch portion. In one series of embodiments, when the spring is located within the groove or channel, the first clutch portion may be unable to move axially relative to the second clutch portion. The spring may thus act as a blocker to axially lock the first and second clutch portion. The first and second clutch portion may be configured to move axially together. The first lock barrel may comprise a retainer. The retainer may be configured to retain the spring in a primed condition. For example, whereby the spring is retained within the groove or channel and connects the first and second clutch portions. By ‘primed’ it is intended to mean pre-tensioned. The retainer may comprise a pin. The cylinder lock may be put into the second condition by removal of the retainer. The retainer may be configured to retain the spring in the primed condition. The cylinder lock may be configured such that removal of the retainer allows the spring to spring open or expand. In some embodiments, upon removal of the retainer, the spring fires into a non-engaging position wherein the spring is not received within the groove or channel of the first clutch portion. When the spring is fired, the first clutch portion may be freely moveable relative to the second clutch portion. The cylinder lock may further comprise a rotor. The rotor may be configured to transfer a rotation from the first lock barrel to the clutch mechanism. The rotor may be configured to transfer a rotation force from the first lock barrel to the second clutch portion and / or the cam. The rotor may be unable to move axially e.g. relative to the first lock housing and / or the cam housing. The rotor may comprise a circumferential groove. The rotor may be located within a ring on the cam housing. The rotor may be retained within the ring by a rotor pin extending through the cam housing and into the circumferential groove. The retainer may extend from and / or be part of the first lock barrel. The retainer may extend through or past the first rotor e.g. when in the first condition and the spring is in the primed condition. The cylinder lock may be configured such that a key inserted into the barrel pushes on and axially moves the first clutch portion. The first clutch portion may extend into the first barrel. The first clutch portion may be freely rotatable in both the first and second conditions. The second clutch portion and the cam may be provided with engaging formations for connecting the second clutch portion and the cam e.g. such that rotation of the second clutch portion causes rotation of the cam. The second clutch portion may comprise an opening. The first clutch portion may extend through the opening. The cylinder lock may further comprise a second lock barrel. The clutch mechanism may comprise a third clutch portion for engaging the second lock barrel with the cam. The clutch mechanism may be configured to bias the third clutch portion into engagement with the cam when a key is not located in the first lock barrel 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 the cylinder lock, Figure 3 is an exploded diagram of the cylinder lock, Figure 4 is a perspective view of a cam and clutch assembly, Figure 5 is an end-on view of a cam, Figure 6 is a perspective view of a partial clutch assembly, Figure 7 is a perspective view of a clutch portion, Figure 8 is a perspective view showing the inside of a rotor, Figure 9 is a perspective view showing the inside of a rotor, Figure 10 is a cross-section through the cylinder lock in normal use, and Figure 11 is the cross-section of Figure 10 after the cylinder lock has been snapped. Specific description Turning now to Figures 1 and 2, 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 and second lock housings 2, 3 are each provided with a respective lock barrel 6, 7 therein. 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 are connected to the cam housing 4 by a series of securing pins 21, 31 respectively which pass through apertures in the first and second lock housings 2, 3 and the cam housing 4. A pair of rotor pins 43 extend through the width of the cam housing 4 as described later. In Figure 3, the cylinder lock 1 is shown in exploded form. The first and second lock housings 2, 3 each have an axial aperture 32 therein which is located over the pegs 44 extending from the cam housing 4. The lock housings 2,3 are then secured by the respective securing pins 21, 31 which pass through the pegs 44 to secure the lock 1 together. Each of the lock housings 2,3 are provided with a series of bores in which lock pins are provided (not shown) for preventing the rotation of the first barrel 6 and second barrel (not shown) in the conventional manner. The cam housing 4 is has a pair of arms with cam rings 45 located on the end. Between the first barrel 6 and second barrel (not shown in Figure 3) is a clutch mechanism 8 which extends through the two cam rings 45 and cam 5. The clutch mechanism 8 comprises a first rotor 41 secured in a first cam ring 45 via a retainer pin 43, and a second rotor 42 secured in a second cam ring 45 via a retainer pin 43. The first and second rotors 41, 42 have a narrow groove extending around their circumference and which receive a portion of which the retainer pins 43. The first and second rotors 41,42 are thus rotatable relative to the cam rings 45 but are blocked from moving axially due to the retainer pins 43. Between the first and second rotors 41, 42 are a first clutch portion 81, a second clutch portion 82 and a third clutch portion 83, a spring 84, a clutch spring 86 and an intermediate spring 85. The first clutch portion 81 extends through a first aperture 411 located in the centre of the first rotor 41, and through corresponding apertures in the second and third clutch portions 82, 83. A retainer 85 is connected to or partially received in the end of the first lock barrel 6 and extends through the second aperture 412 in the first rotor 41. The clutch mechanism 8 will further be described with additional reference to Figures 4 to 9. Figure 4 shows the assembled clutch mechanism 8, cam 5 and cam housing 4, with the first and second lock housings 2, 3 and barrels 6, 7 removed. The first rotor 41 is located in one of the rings 45 and secured by a rotor pin 43. The first clutch portion 81 projects from the centre of the first rotor 41 and the retainer 85 extends from the second aperture located below the first aperture (in the orientation as shown) toward the first lock barrel (not shown). The first clutch portion 81 is axially moveable relative to the first rotor 41 as indicated by the double arrow. Turning now to Figures 5 to 9, there are shown elements of the clutch mechanism in isolation. The cam 5 in Figure 5 is shown axially. 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 provided a cam wall 54 having a pair of cam recesses 53 therein for receiving corresponding teeth of the second and third clutch portions 82, 83 to rotationally engage the cam 5 with one of the clutch portions 82, 83. Figures 6 and 7 shown the first to third clutch portions 81, 82, 83. The second and third clutch portions 82, 83 are approximately disc shaped, but are provided with a lower surface (in the orientation shown) corresponding with the profile of the cam wall 54 and teeth 821, 831 corresponding with the cam recesses 53. As shown in Figures 8 and 9, the first and second rotors also have a profile corresponding to that of the cam wall and cam recesses such that they receive the corresponding sections and teeth 811, 831 of the second and third clutch portions 82, 83. The second and third clutch portions 82, 83 are thus able to move axially into engagement with the cam 5 while remaining engaged with their corresponding rotors 41, 42. The second clutch portion 82 is provided with an annular recess 822 which eccentrically surrounds the first clutch portion 81. The spring 84 is located within the annular recess 822 and secured to the second clutch portion 82. The annular spring 84 is a torsion spring and has a spring arm 84a which is bent inwardly and passes across the surface of the second clutch portion 82 and into an annular groove 81a first clutch portion 81. The spring arm 84a is held under pre-tension by the retainer 85 which is held in position by the second aperture in the first rotor 41 (not shown). The spring arm 84a physically blocks the first clutch portion from moving axially through the first aperture in second clutch portion 82 and thus ensures that the first and second clutch portions 81, 82 are axially locked (i.e. in the lengthwise dimension of the lock 1) despite the first clutch portion 81 being freely rotatable. The operation of the lock 1 will now be described with reference to Figures 10 and 11. Figure 10 is a cross-section through the lock 1 in the plane A-A of Figure 1. The lock 1 is in a first condition which corresponds to a default, locked state. Under the action of the spring 86, the third clutch portion 83 is biased into a central position where it engages with the cam 5 and pushes the second clutch portion 82 out of engagement with the cam. Since the second clutch portion 83 is rotationally locked with the second rotor 42, which in turn is rotationally locked with the second barrel (not shown), the cam 5 is unable to rotate and the lock 1 is locked. When a user wishes to unlock the lock 1, a key can be inserted into either first or second lock barrel 6, 7. The key would be configured to depress locking pins in the known manner to allow the barrel to rotate. On the internal side, a key inserted into barrel 7 thus permits the barrel 7 to rotate on rotation of the key. This in turn drives rotation of the second rotor 42, third clutch portion 83 and cam 5, thereby actuating the lock 1 and any locking mechanism in which it is installed. On the exterior side, a key is insertable into the first barrel 6, depressing the pins 61 thereby allowing the barrel 6 to rotate. The tip of the key pushes axially on the first clutch portion 81, which projects into the end of the barrel. The first clutch portion 81 is thus pushed towards the cam 5. The first clutch portion 81 is axially connected to the second clutch portion by way of the spring arm 84a which is retained under spring tension in the groove 81a by the retainer 85. Pushing the first clutch portion 81 thus pushes the spring arm 84a which pushes the second clutch portion 82 into engagement with the cam 5 and pushes the third clutch portion 83 out of engagement with the cam against the biasing force of spring 86. The second barrel 7 on the internal side of the lock no longer blocks the cam from rotation. The first barrel 6 is thus rotationally locked to the cam 5 via the first rotor 41 and the second clutch portion 82. The first clutch portion 81 is configured to only move the second clutch portion 82 axially, and is not involved in any torque applied via the barrel to the second clutch portion and the cam. The user can then rotate the key in the barrel 6 and actuate the cam 5 and the lock 1. The lock 1 can be provided with conventional anti-picking or anti-bumping pins, or with anti-drill pins in the body of the lock without affecting its functionality. 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. As also shown in Figures 3 and 10, the first lock housing 2 is mounted on a peg 44 extending from the cam housing 4 by securing pins 21. This forms a frangible region which will break preferentially upon application of a strong force to the exposed end of the lock 1. This prevents the lock from being snapped in half through the middle of the cam housing. This is shown in Figure 11 by the first lock housing 2 being separated from the cam housing 4. Upon snapping of the lock 1, the lock 1 enters a second condition. The withdrawal of the first lock barrel 6 removes the retainer 85 from its position in the first rotor 41. As discussed previously, the retainer 85 holds the spring 84 under tension. Once the retainer 85 is removed, the spring 84 is released such that the spring arm 84a springs out of the groove 81a on the first clutch portion. The connection between the first and second clutch portions 81, 82 is removed and the first clutch portion 81 is axially displaceable relative to the second clutch portion 82. Without the spring 84 connecting the first and second clutch portions 81, 82, the biasing force of the intermediate spring 87 acts upon the first clutch portion 81 and pushes it inwards as shown by the arrow in Figure 11. A minimal part of the first clutch portion 81 remains projecting from the first rotor 41 thus providing an attacker with little material to grip and attempt to manipulate the lock. In this second condition, the first clutch portion 81 is freely moveable relative to 5 the second clutch portion 82 both axially and rotationally. Without the spring arm 84a in the groove 81a, the movement of the first clutch portion 81 is unable to move the second clutch portion 82 into an engaging position with the cam 5. The clutch spring 86 biases the third clutch portion 83 into engagement with the cam 5 such that even with manipulation of the lock 1 from the external side, the internal side barrel 7 ensures that 10 it is not possible to actuate the cam 5. Thus, should the lock be snapped, it is no longer actuable from the external, snapped side, while still being fully operable from the internal side.

Claims

1. A cylinder lock comprising:a first lock barrel;a cam; anda clutch mechanism configured to connect the first lock barrel to the cam when a key is inserted into the barrel, whereinthe clutch mechanism comprises a first clutch portion and a second clutch portion, configured such thatin a first condition, the first and second clutch portions are axially movable together to engage and disengage the cam, andin a second condition, the first clutch portion is freely axially movable relative to the second clutch portion, such that the clutch mechanism cannot engage the cam.

2. The cylinder lock according to claim 1, wherein the first 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 any one of the preceding claims, wherein the cylinder lock is configured such that the second condition is caused by the first lock barrel being removed and / or disconnected from the cylinder lock.

4. The cylinder lock according to any one of the preceding claims, wherein the first clutch portion and the second clutch portion are connectable by a spring in the first condition.

5. The cylinder lock according to claim 4, wherein the second clutch portion comprises a recess for retaining the spring, and wherein the first clutch portion comprises a groove or channel for receiving a portion of the spring in the first condition.

6. The cylinder lock according to claim 4 or claim 5, wherein the first lock barrel comprises a retainer configured to retain the spring in a primed condition whereby the spring is retained within the groove or channel and connects the first and second clutch portions.

7. The cylinder lock according to claim 6, wherein the cylinder lock is put into the second condition by removal of the retainer.

8. The cylinder lock according to claim 7, wherein upon removal of the retainer, the spring fires into a non-engaging position wherein the spring is not received within the groove or channel of the first clutch portion.

9. The cylinder lock according to any one of the preceding claims, further comprising a rotor configured to transfer a rotation from the first lock barrel to the clutch mechanism.

10. The cylinder lock according to claim 9 when dependent upon any one of claims 6 to 8, wherein the retainer extends from the first lock barrel through or past the rotor to retain the spring in the primed condition.

11. The cylinder lock according to any one of the preceding claims, configured such that a key inserted into the barrel pushes on and axially moves the first clutch portion.

12. The cylinder lock according to any one of the preceding claims, wherein the first clutch portion is freely rotatable in both the first and second conditions.

13. The cylinder lock according to any one of the preceding claims, wherein the second clutch portion and the cam are provided with engaging formations for connecting the second clutch portion and the cam, such that rotation of the second clutch portion causes rotation of the cam.

14. The cylinder lock according to any one of the preceding claims, wherein the second clutch portion comprises an opening, and wherein the first clutch portion extends through the opening.

15. The cylinder lock according to any one of the preceding claims, further comprising a second lock barrel, andwherein the clutch mechanism comprises a third clutch portion for5 engaging the second lock barrel with the cam,and wherein the clutch mechanism is configured to bias the third clutch portion into engagement with the cam when a key is not located in the first lock barrel.13

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