Clutch assembly

Abstract

A clutch assembly for a cylinder lock. The cylinder lock comprises a body 2, opposed first and second cylinders 3a,b comprising keyholes for receiving a key, which unlocks and permits rotation of the

Description

[0001] This invention relates to a clutch assembly, and in particular to a clutch assembly for a cylinder lock for use with a door or the like. Further, this invention relates to a cylinder lock incorporating a clutch assembly. Background

[0002] Cylinder locks are commonly used as a standard locking mechanism for doors, consisting of a pin tumbler lock disposed either side of a rotator, the pin tumbler being unlocked via the insertion of a correctly fitting key into a cylinder, permitting the cylinder to rotate and, as such, actuate the rotator. The rotator actuates a cam which in turn actuates a latch of the door.

[0003] One problem faced by prior art cylinder locks is that they are vulnerable to a method of forced entry known as lock snapping. This involves using a tool to apply a strong torque to the cylinder, thereby breaking the mechanism and allowing the cylinder to be removed, providing access to the cam and latch.

[0004] A common method of overcoming this problem is the use of sacrificial sections in the lock mechanism, whereby a structurally weakened part of the lock body will break away when strong torque is applied leaving behind enough of the lock mechanism to prevent access to the latch. However, access to the rotator may still be possible once the sacrificial sections have been removed.

[0005] A method of overcoming this problem is the use of an axially moveable, captured clutch mechanism as shown in GB2491099A where a captured plunger mechanism is removed with a sacrificial section of the outer cylinder. However, as the plunger is removed with the cylinder the cam is left accessible.

[0006] It is an aim of the present invention to overcome these problems and to provide a clutch assembly that cannot be actuated when one of the cylinders has been removed. Summary of Invention

[0007] In a first non-limiting embodiment of the present invention there is provided a clutch assembly for a cylinder lock, the cylinder lock comprising: a body; opposed first and second cylinders comprising respectively first and second keyholes disposed in opposite ends thereof for receiving a key, the first and second cylinders being lockable relative to the body, and the first and second cylinders being unlocked and rotatable relative to the body when actuated by a correctly fitting key inserted into the first or second keyhole; a rotator disposed between the first and second cylinders, the rotator being rotatable relative to the body when the first or second cylinder is rotated by the key inserted into the first or second keyhole; the rotator comprising a cam and the clutch assembly; wherein the clutch assembly comprises opposed first and second selectively engageable clutch elements, wherein the first and second clutch elements engage with each other and with a cam, and wherein the cam is rotatable only when the first and second clutch elements are engaged.

[0008] The cam is a rotatable element which is part of the rotator, and which actuates the latch mechanism of a door or the like when it is rotated. Advantageously, the present clutch assembly may block access to the cam after removal of a cylinder due to lock snapping. Whilst the clutch assembly of the present invention is described as being for use with a cylinder lock, other mechanisms may be used to actuate the clutch assembly, such as a thumb turn or electronic lock which could replace one or both of the cylinders.

[0009] The opposed first and second clutch elements may be selectively engageable via at least one engagement means. Further, the at least one engagement means may be disposed on opposed engagement surfaces of each of the first and second clutch elements. Further still, the at least one engagement means may comprise a plurality of interlocking teeth. Therefore, when the first and second clutch elements are engaged, rotation of one clutch element will effect rotation of the other.

[0010] The first and second clutch elements may further comprise means for selectively engaging with a cam. Specifically, the first and second clutch elements may each comprise a notch disposed towards an opposed engagement surface thereof, with the cam comprising a protrusion that may be enclosed by the clutch element notches when engaged, though any alternative engagement mechanism is envisaged.

[0011] The clutch assembly may further comprise first and second input shafts disposed coaxially between the first and second cylinders and the first and second clutch elements. The first and second input shafts may be slidable along the axis, and the first and second clutch elements may be actuatable via respective first and second input shafts.

[0012] The first and second input shafts may comprise a body portion for attachment to a respective cylinder, a shoulder portion and a head portion.

[0013] The first and second clutch elements may comprise a coaxial aperture extending therethrough, and the head portion of the first and second input shafts may be disposed respectively in the aperture. The aperture may include a narrow portion at an end adjacent the cylinder and a widened portion towards the engagement surface thereof, and the first or second input shaft may be retained within the aperture whereby the head portion of the first or second input shaft may be widened to sit within the widened portion of the aperture but be prevented from passing through the narrow portion. The widened portion of the head portion of the first and second input shaft may be widened with a circlip.

[0014] The first and second input shafts may engage with the first and second clutch elements via mating parts on the first and second clutch elements and the first and second input shafts. The mating parts may comprise a depression on the distal surface of the clutch elements and the shoulder portion of the respective input shafts. The mating parts may comprise polygonal side faces such as being triangular, square, hexagonal or the like to provide an abutment surface so that rotation of the first or second input shaft, when engaged with the first or second clutch element, rotates the first or second clutch element.

[0015] The first and second input shafts may be attachable to the respective first and second cylinders with biased means, wherein the input shafts are biased so the respective mating parts are engaged.

[0016] The first and second input shafts may be slidable between a first position where the mating parts of the first and second input shafts are engaged with the mating parts of the first and second clutch elements and a second position where the mating parts of the first or second input shaft is engaged with the mating parts of the respective first or second clutch element and the mating parts of the other input shaft is not engaged with the mating parts of the other respective clutch element. The input shafts may be slid from the first position to the second position by contact with the first or second input shaft upon insertion of a key into the keyhole of a respective cylinder.

[0017] The body portion of the first or second input shaft may be constantly engaged with the first or second cylinder. In particular, the body portion of the first or second input shaft may be at least partially retained in a depression on the first or second cylinder. This enables rotation of the input shaft by the cylinder and prevent rotation of the input shaft if the cylinder is locked to the body.

[0018] The length of the first and second the input shafts may be such that when one of the input shafts is in the second position, the opposed input shaft is pushed by the other input shaft towards the opposite cylinder, so that the opposed first or second input shaft is not engaged with the opposed first or second clutch element. If both input shafts are engaged with the clutch elements, then the clutch assembly will be locked even if a key is inserted to unlock one of the cylinders because the opposed clutch element will be engaged with the opposed input shaft which may be engaged to the opposed cylinder which is locked.

[0019] The clutch elements may further comprise a groove for receiving a locking pin disposed in the body of the cylinder lock, wherein if either of the first or second cylinders are removed, the clutch element adjacent the removed cylinder is moved to a third position, where the locking pin engages with the groove to prevent removal of the clutch element.

[0020] This is advantageous because when the clutch element is secured with the locking pin, access to the rotator and cam is prevented. Description of the Drawings

[0021] Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which:

[0022] Figure 1 shows a side view of a cylinder lock comprising a clutch assembly according to the present invention where half of the cylinder lock is in cross-section;

[0023] Figure 2 shows a top view of the cylinder lock of Figure 1;

[0024] Figure 3 shows a front view of the cylinder lock;

[0025] Figure 4 shows a cross-sectional view of a clutch element;

[0026] Figure 5 shows a side view of the clutch element;

[0027] Figure 6 shows a view of the distal face of the clutch elements;

[0028] Figure 7 shows an isometric view of a clutch element;

[0029] Figure 8 shows an end view of an engagement surface of a clutch element;

[0030] Figure 9 shows a cross-sectional side view of an input shaft;

[0031] Figure 10 shows a plan view of an input shaft;

[0032] Figure 11 shows a cross-sectional side view of the cylinder lock with the securing means engaged; and

[0033] Figure 12 shows an exploded view of an alternative embodiment of the present invention. Detailed Description

[0034] Referring to Figures 1 to 10 there is shown a cylinder lock generally indicated 1 comprising a body generally indicated 2, the body 2 containing opposed first and second cylinders generally indicated 3a,b. Each cylinder 3a,b comprises respectively first and second keyholes generally indicated 4 disposed in opposite ends thereof for receiving a key (not shown). The cylinders 3a,b further comprise a series of pin tumblers 5 disposed at different positions throughout the keyhole 4, at least partially disposed in tumbler receiving channels 7 in a tumbler body 8. Such pin tumblers 5 are in accordance with the state of the art to lock the cylinders 3a,b to the body 2 and are releasable by insertion of a correctly fitting key into the keyhole 4. The cylinders 3a,b are disposed either side of a rotator generally indicated 9.

[0035] The rotator 9 comprises a cam generally indicated 10 operable to connect with a lock mechanism in a door (not shown), and a clutch assembly generally indicated 20. The clutch assembly 20 comprises opposed first and second selectively engageable clutch elements 22a,b. The clutch elements 22a,b are disposed coaxially with respect to the cylinders 3a,b. As best shown in Figures 6 and 7, the clutch elements 22a,b each comprise a hexagonal depression 24 on a distal face 26 thereof, and a circular depression 28 on an engagement surface 30 thereof. The clutch elements 22a,b comprise a series of interlocking teeth and notches 32 on the engagement surface 30, and the interlocking teeth and notches 32 are provided so that the opposed clutch elements 22a,b can engage with each other. The engagement surface 30 further comprises a notch 36 for engagement with the cam 10. The clutch elements 22a,b further comprise an aperture 38 extending the length of the clutch elements 22a,b from the hexagonal depression 24 on the distal face to the circular depression 28 on the engagement surface 30. The clutch elements 22a,b further comprise a groove 40 extending around an outer face 42 of the clutch elements 22a,b. As shown in Figure 12, an inside surface 96 of the cam 10 comprises a protrusion 98 which is retained within the notches 36 of the engaged cam elements 22a,b, to engage the cam 10 with the clutch assembly, so when a cylinder 3a,b and clutch assembly are rotated, the cam 10 is rotated as well to actuate the latch of a door.

[0036] Disposed at least partially along the aperture of each clutch element 22a,b are opposed, coaxial first and second input shafts 44a,b. Each input shaft 4a,b, comprises a body portion 46, and shoulder portion 48 and a head portion 50. The shoulder portion 48 is shaped to engage with the hexagonal depression 24 of each clutch element 22a,b. The head portion 50 of the input shaft 44a,b comprises a circlip 52. As shown in Figure 1, the input shafts 44a,b are disposed within the aperture 38 of the clutch elements 22a,b and the circlip 52 sits within the circular depression 28, and has a diameter larger than that of the aperture 38 of the clutch elements 22a,b to prevent removal of the input shaft 44a,b from the aperture 38. The input shaft 44a,b is connected to the cylinder 3a,b via springs 54. The input shafts 44a,b are further attached to the cylinder 3a,b via retaining pins (not shown), disposed through a plurality of retaining apertures (not shown) in the cylinder body 2.

[0037] When in a first position, the input shafts 44a,b are partially retained within the clutch elements 22a,b. Specially, the shoulder portion 48 of the first and second input shafts 44a,b is retained within the hexagonal depression 24 of the first and second clutch elements 22a,b. Opposed input shafts 44a,b are also in contact at the end of the head portions 50 thereof. In such a first position, the first and second cylinders 3a,b are prevented from rotation relative to the body 2 by the tumbler pins 5.

[0038] When a correctly fitting key is inserted into the keyhole 4 of one of the first or second cylinders 3a,b the end of the key abuts the distal face of the body portion 46 of the first or second input shaft 44a,b, moving the input shaft 44a,b along the axis of the cylinder lock body 2, and also within the aperture 38 in the clutch element 22a,b, to a second position. The shoulder portion 48 of the input shaft 44a,b is also pushed within the hexagonal depression 24 of the respective clutch element 22a,b. When the key is fully inserted, the input shaft 44a,b in contact with the key is moved to its maximum depth within the aperture 38 of the clutch element 22a,b, causing the input shaft 44a,b to push the opposed input shaft 44a,b so that the shoulder portion 48 of the opposed input shaft 44a,b is disengaged from the opposed clutch element 22a,b.

[0039] For example, if the key is inserted into cylinder 3a, the key also releases the tumbler pins 5 from the cylinder 3a to unlock the cylinder 3a relative to the cylinder lock body 2 to permit rotation of the cylinder 3a. Rotation of cylinder 3a also rotates input shaft 44a, which rotates the first and second clutch elements 22a,b and cam 10 to actuate the door latch. Clutch element 22b rotates relative to input shaft 44b because it is disengaged therefrom.

[0040] The cylinder lock further comprises an anti-tamper mechanism to protect the lock should one of the cylinders 3a,b be snapped off. As shown for example in Figure 1, 2 and 11, the cylinder lock body 2 is separated into two cylinder sections 60,62 and a rotator section 64, separated by frangible sections 66,68.

[0041] The anti-tamper mechanism further comprises security pins 70 disposed in apertures 72 in the rotator section 64 of the body 2 of the cylinder lock 1, adjacent to the clutch elements 22a,b. The security pins 70 are biased with spring 74 disposed at the base of the aperture 72, which urge the security pins 70 against the clutch elements 22a,b.

[0042] If the lock is attacked, for example, by a screwdriver, the lock will break at the frangible section 66 and the cylinder section 60, containing cylinder 3a and respective tumbler pins 5, will be removed. In removing cylinder section 60, input shaft 44a will pull clutch element 22a away from the clutch element 22b. Clutch element 22a is then moved to a position as shown in Figures 11-13, in which the securing pin 70 extends into the groove 40 of the clutch element 22a. This prevents clutch element 22a from being removed from the clutch assembly and therefore prevents access to the cam 10 and door latch.

[0043] An alternative embodiment is show in Figure 12, where the body of a cylinder lock generally indicated 80 is modular, and comprises separable cylinder portions 82,84 and rotator portion 86. The clutch assembly and other components are the same as in the previous embodiment, and so like reference numerals have been used.

[0044] This alternative cylinder lock 80 can be installed in doors or the like have different depths. The cylinder portions and body portions are separable and can be connected with protrusions 88 in the rotator portion 86 which locate into apertures 90 in the cylinder portions 82,84, which are then secured with securing pins 92. A washer 94 is provided coaxial with the cylinders 3a,b and clutch elements 22a,b to aid rotation thereof.

[0045] Should the cylinder lock 80 be installed in a door wider than the length of the cylinder lock 80, then the or each cylinder portions 82,84 can be disconnected from the rotator portion 86, and spacers (not shown) can be secured in between.

Claims

1. A clutch assembly for a cylinder lock, the cylinder lock comprising:a body;opposed first and second cylinders comprising respectively first and second keyholes disposed in opposite ends thereof for receiving a key, the first and second cylinders being lockable relative to the body, and the first and second cylinders being unlocked and rotatable relative to the body when actuated by a correctly fitting key inserted into the first or second keyhole;a rotator disposed between the first and second cylinders, the rotator being rotatable relative to the body when the first or second cylinder is rotated by the key inserted into the first or second keyhole; the rotator comprising a cam and the clutch assembly;wherein the clutch assembly comprises opposed first and second selectively engageable clutch elements, wherein the first and second clutch elements engage with each other and with a cam, and wherein the cam is rotatable only when the first and second clutch elements are engaged.

2. A clutch assembly according to claim 1, wherein the opposed first and second clutch elements are selectively engageable via at least one engagement means.

3. A clutch assembly according to claim 2, wherein the at least one engagement means is disposed on opposed surfaces of each of the first and second clutch elements.

4. A clutch assembly according to claims 2 or 3, wherein the at least one engagement means comprises a plurality of interlocking teeth.

5. A clutch assembly according to claims 1 to 4, wherein the first and second clutch elements further comprise means for selectively engaging with the cam.

6. A clutch assembly according to claims 1 to 5, further comprising first and second input shafts disposed coaxially between first and second cylinders and the first and second clutch elements, the first and second input shafts beingslidable along the axis, and wherein the first and second clutch elements are actuatable via respective first and second input shafts.

7. A clutch assembly according to claim 6, wherein the first and second input shafts comprise a body portion attachable to a respective cylinder, a shoulder portion and a head portion.

8. A clutch assembly according to claim 7, wherein the first and second clutch elements comprise a coaxial aperture extending therethrough, and the head portion of the first and second input shafts are disposed respectively in the aperture.

9. A clutch assembly according to claim 7 or 8, wherein the first and second input shafts engage with the first and second clutch elements via mating parts on the clutch elements and the input shafts.

10. A clutch assembly according to claim 9, wherein the mating parts comprise a depression on the distal surface of the first and second clutch elements to receive the shoulder portion of the respective first and second input shafts.

11. A clutch assembly as claimed in any of claims 9 or 10, wherein the first and second input shafts are attachable to the respective first and second cylinders with biased means, wherein the input shafts are biased so the respective mating parts are engaged.

12. A clutch assembly according to claim 11, wherein the first and second input shafts are slidable between a first position where the mating parts of the first and second input shafts are engaged with the mating parts of the first and second clutch elements and a second position where the mating parts of the first or second input shaft is engaged with the mating parts of the respective first or second clutch element and the mating parts of the other input shaft is not engaged with the mating parts of the other respective clutch element, and wherein the input shafts are slid from the first position to the second position by contact with the first or second input shaft upon insertion of a key into the keyhole of a respective cylinder.

13. A clutch assembly according to claim 12 wherein the length of the first and second the input shafts is such that when one of the first or second input shafts is in the second position, the opposed first or second input shaft is pushedtowards the opposite cylinder, so that the opposed first or second input shaft is disengaged from the opposed first or second clutch element.

14. A clutch assembly lock according to claim 12 or claim 13, wherein the body portion of the first and second input shaft is at least partially retainable in a 5 depression on the first and second cylinder.

15. A clutch assembly according to claims 1 to 14, wherein the clutch elements further comprise a groove for receiving a locking pin disposed in the body of the cylinder lock, wherein if either of the first or second cylinders are removed, and the clutch element adjacent the removed cylinder is moved to a 10 third position, where the locking pin engages with the groove to prevent removal of the clutch element.

16. A cylinder lock comprising the clutch assembly of any preceding claim.T +44(0)30 0300 2000A

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