WO2006092597A1

WO2006092597A1 - Cylinder tumbler lock mechanism

Info

Publication number: WO2006092597A1
Application number: PCT/GB2006/000738
Authority: WO
Inventors: Barrie Samuel Harper
Original assignee: FAB sro
Current assignee: FAB sro
Priority date: 2005-03-02
Filing date: 2006-03-02
Publication date: 2006-09-08
Anticipated expiration: 2007-09-02

Abstract

A cylinder tumbler lock mechanism comprises tumblers resiliently biased into a first locking position. The tumblers include a formation for engagement with a side of a key blade. The lock includes a first tumbler movable in a first direction from the first locking position to a second releasing position and a second tumbler movable in a second direction, opposite to the first direction, from the first locking position to the second releasing position. The formation on the first tumbler is on a first side edge for engaging a first side of a key inserted through the opening. The formation on the second tumbler is on a first side edge of the tumbler for also engaging said first side of a key inserted through the opening. The key comprises a shaft with a first operating edge and a second operating edge forming opposing edges of a groove extending along a side of the shaft. The width of the groove measured between the opposite operating edges varies along the shaft.

Description

Cylinder Tumbler Lock Mechanism

This invention relates to a cylinder tumbler lock mechanism, to a key for operating such a lock mechanism and to a method of making such a key. The invention is particularly, but not exclusively, concerned with disc tumbler lock mechanisms for use in vehicles.

There is always a desire to make locks more secure and in particular less vulnerable to being picked. It is an object of the invention to provide a cylinder tumbler lock mechanism that is difficult to pick.

According to the invention, there is provided a cylinder tumbler lock mechanism comprising a plug rotatably mounted in a housing, the plug including a row of slots formed therein, each slot extending in a direction transverse to the length of the row and containing a tumbler having an opening therethrough for allowing insertion of a key into the plug, the tumbler being slidably mounted in the slot and movable between a first locking position in which one end of the tumbler projects out of an open end of the slot and a second releasing position in which the end of the tumbler is located within the slot, the tumbler being resiliently biased into the first locking position and including a formation on a side edge of the opening for engagement with a side of a key inserted through the opening, wherein the tumblers include a first tumbler movable in a first direction from the first locking position to the second releasing position and a second tumbler movable in a second direction, opposite to the first direction, from the first locking position to the second releasing position, the formation on the first tumbler being on a first side edge for engaging a first side of a key inserted through the opening and the formation on the second tumbler being on a first side edge of the tumbler for also engaging said first side of a key inserted through the opening.

By providing two tumblers which are engaged on the same side edge by the same side of the key but are movable in opposite directions against respective resilient biases into releasing positions, it can be made significantly more difficult to pick the lock.

Preferably at least part of the formation on the second tumbler is obscured by the formation on the first tumbler, when viewed in the direction of insertion of the key.

Preferably there are at least three tumblers and the first and second tumblers are adjacent to one another. With such arrangements, picking of the second tumbler is impeded by the presence of the first tumbler.

Preferably the formation on the side edge of the opening of at least one tumbler is on a second side edge opposite the first side edge for engaging a second, opposite, side of a key inserted through the opening.

The first and second directions are described above as opposite. It should be understood that while they may not be exactly opposite to one another they are preferably offset from one another by 180 degrees.

The tumblers in lock mechanisms of the kind referred to above are commonly referred to as disc tumblers to distinguish them from pin tumblers . The tumblers employed in the present invention may be described as disc tumblers. The opening in each tumbler may extend to the edge of a tumbler on one side; for example, a tumbler may be ^λC shaped, but it is preferred that the opening in the tumbler is enclosed on all sides by parts of the tumbler. Each tumbler is preferably resiliently biased by a respective spring, preferably a compression spring.

The lock mechanism preferably further includes a key for inserting through the openings in the tumblers . The key preferably comprises a shaft including a first operating edge and a second operating edge, the first operating edge and the second operating edge form opposing edges of a groove extending along a side of the shaft, and the first operating edge is suitable for abutting the formation on the side edge of the first tumbler, and the second operating edge is suitable for abutting the formation on the side edge of the second tumbler.

The key of the lock mechanism has two operating edges on the same side. In the embodiment of the invention, some tumblers engage one of the operating edges when the key is inserted into the lock while other tumblers engage the other one of the operating edges, but for any one tumbler only one operating edge is controlling the position of that tumbler and therefore the position of the other operating edge is not significant. Accordingly, the distance between the first and second operating edges may vary; thus, the distance between the first operating edge and the second operating edge at a first location along the shaft may be less than the distance between the first operating edge and the second operating edge at a second location along the shaft. Generally there will be several tumblers and it is accordingly preferred that the distance between the first operating edge and the second operating edge at a third location along the shaft for abutting a formation on the side edge of a third tumbler is different from the distances between the first operating edge and the second operating edge at the first and second locations along the shaft.

Preferably the first operating edge has an undulating profile and similarly the second operating edge preferably has an undulating profile. Preferably the key of the lock mechanism also has first and second operating edges on its other side. Such a key is able to operate a lock in which tumblers have formations on opposite sides of their openings and/or the key can be reversible so that it is able to operate the lock when inserted in either of two orientations 180 degrees apart. Conveniently, the key shaft is provided with 180 degree rotational symmetry to facilitate reversibility.

According to another aspect of the invention there is provided a key suitable for use in a cylinder tumbler lock mechanism as defined above, the key comprising a shaft including a first operating edge and a second operating edge, wherein the first operating edge and the second operating edge form opposing edges of a groove extending along a side of the shaft, the first operating edge is suitable for abutting the formation on the side edge of the first tumbler, and the second operating edge is suitable for abutting the formation on the side edge of the second tumbler.

The key may incorporate any of the features referred to above when describing the combination of the lock and key.

According to yet another aspect of the invention there is further provided a key for use in a lock mechanism, the key comprising a shaft including a first operating edge and a second operating edge, wherein the first operating edge and the second operating edge form opposing edges of a groove extending along a side of the shaft. The first operating edge is suitable, during use, for abutting a formation on a side edge of a first tumbler in the lock mechanism, and the second operating edge is suitable, during use, for abutting a formation on a side edge of a second tumbler in the lock mechanism.

According to yet another aspect of the invention there is provided a key for use in a lock mechanism, the key comprising a shaft including a first operating edge and a second operating edge forming opposing edges of a groove extending along a side of the shaft, wherein the width of the groove measured between the opposite operating edges varies along the shaft.

By providing a groove of varying width it becomes possible to use both opposite edges of the groove as operating edges for effecting controlled movement of the tumblers, instead of just one edge. That enables a more secure lock to be provided, as will become clear from the further description below. The key according to any aspect of the invention may similarly incorporate any of the features referred to above when describing the combination of the lock and key.

A novel method of cutting a key is also preferably adopted to provide a key according to the invention. Thus the • invention also provides a method of cutting a key as defined above, in which a cutter is moved along the path of the groove in a first pattern of movement to form the first operating edge and is subsequently moved along the path of the groove in a second pattern of movement to form the second operating edge .

Preferably the cutter is moved in a first direction to form the first operating edge and is subsequently moved in a second direction opposite to the first to form the second operating edge. The first direction is preferably a direction from beyond the free end of the key blade into the blade.

A method of the kind defined above enables a key according to the invention to be cut quickly and simply.

According to the invention, there is also provided a cylinder tumbler lock mechanism comprising a key as defined above, a plug rotatably mounted in a housing, the plug including a row of slots formed therein, each slot extending in a direction transverse to the length of the row and containing a tumbler having an opening therethrough for allowing insertion of a key into the plug, the tumbler being slidably mounted in the slot and movable between a first locking position in which one end of the tumbler projects out of an open end of the slot and a second releasing position in which the end of the tumbler is located within the slot, the tumbler being resiliently biased into the first locking position and including a formation on a side edge of the opening for engagement with one of the operating edges of the key when, in use, the key is inserted through the opening.

By way of example, an embodiment of the invention will now be described with reference to the accompanying drawings, of which:

Figure 1 is a plan view of a plug for a disc tumbler cylinder lock mechanism;

Figure 2 is a plan view of the tumblers of the lock mechanism shown in Figure 1; Figure 3a is a sectional view through section A-A of Figure 1;

Figure 3b is a sectional view through section B-B of Figure 1;

Figure 4 is a plan view of the first and second sides of a key blade of a key embodying the invention and suitable for operating the lock mechanism;

Figure 5 is a sectional view through section X-X of Figure 4; and

Figure 6 is a plan view of the first and second sides of a key blade.

With reference to Figure 1, a plug 1 of a cylinder tumbler lock mechanism embodying the invention comprises eight slots 3 arranged in a row along the length of the plug 1. The slots are accorded positions one to eight referenced in the drawings as Pl, P2, P3, P4, P5, P6, P7 and P8, the 1st position Pl corresponding to the location closest to the end of the plug into which a key is to be inserted.

Each slot extends in a direction transverse to the length of the plug 1 and contains a tumbler 7 (not shown) . The main body of each slot 3 is of rectangular cross-section. At one side of each slot there is further defined a cavity 5 which is open to either the upper surface or lower surface of the plug 1 but closed to the other surface. In the illustrated embodiment shown in Figure 1, the cavities at the 1st, 2nd, 5th and 6th positions are open at the top and the cavities at the 3rd, 4th, 7th and 8th positions are open at the bottom. The side of the slot at which the cavity is defined varies along the row of slots.

Referring now to Figures 2, 3a and 3b each tumbler 7 comprises an opening 9, for allowing insertion of a key into the plug 1, a formation 11 on a side edge 13 of the opening 9, and a protrusion 15.

Each tumbler 7 is dimensioned such that it may be slidably mounted in its associated slot 3 and such that the protrusion 15 fits into the cavity 5. Accordingly, the thickness of the tumblers (not shown) is much less than their height and width.

The tumbler 7 in the 7th position, is shown in Figure 3a and is slidably mounted in the slot 3. The tumbler is shown in a first locking position in which one end 7A of the tumbler 7 projects through the bottom of the slot 3. One end of a compression spring 17 bears against the plug 1 in the cavity 5, whilst the other end of the spring 17 bears against the protrusion 15 on the tumbler 7. The tumbler 7 in the 7th position is thereby resiliently biased in a downward direction into the first locking position by the spring 17.

In the first locking position rotational movement of the plug 1 about its longitudinal axis is prevented by the ends 7A of the tumblers 7 abutting the housing (not shown) upon rotation of the plug 1.

In the same manner as that shown in Figure 3a the tumbler 7 in the 6th position P6 and shown in Figure 3b is slidably mounted in the slot 3 and is resiliently biased into a first locking position by a compression spring 17 located in the cavity 5. In contrast to the above-described 7th position, however, the tumbler in the 6th position is resiliently biased in an upward direction and in the first locking position the end 7A of the tumbler 7 projects through the top end of the slot 3. In the same manner as that shown in Figure 3a, the other tumblers 7 with protrusions 15 on their lower-half (i.e. tumblers in the 3rd, 4th and 8th positions of Figure 1) are also resiliently biased in a downward direction. Likewise, the other tumblers 7 with protrusions 15 on their upper-half (i.e. tumblers in the 1st, 2nd and 5th positions of Figure 1) are resiliently biased in an upward direction in the manner shown in Figure 3b.

All the tumblers 7 are movable between the first locking position and a second releasing position (not shown) . In the second releasing position of each tumbler the end 7A of a tumbler no longer protrudes from an open end of a slot 3 and is, instead, wholly contained within the slot 3. When all the tumblers 7 are in the second releasing position, none of the ends 7A of the tumblers interfere with the housing, and the plug 1 is therefore free to rotate within the housing. Movement of the tumblers 7 from the first locking position to the second releasing position is effected by the blade 19 of a key inserted into the end of the plug 1 along a passageway 9A (shown by dotted lines in Fig. 1) such a distance that the key blade is also inserted into each of the openings 9 in the tumblers.

The key blade 19 is shown in Figures 4 and 5. The key blade comprises a shaft 21 on a first side 27a of which a first operating edge 23a and a second operating edge 23b are defined. The first and second operating edges 23a, 23b are undulating and form opposing sides of a groove 25 extending along the side 27a of the shaft 21. The distance between the first operating edge 23a and the second operating edge 23b at a first location along the shaft is less than the distance between the first operating edge and the second operating edge at a second location along the shaft; the distance is different again at other locations along the groove. The width of the groove 25 therefore varies along the length of the shaft 21. This is in contrast to a key which has a blade such as that shown in Fig. 6 (where the same reference numerals are used as in Fig. 4 to designate corresponding parts) . In the key shown in Fig. 6, the first and second operating edges 23a, 23b remain parallel to one another and the width of the groove 25 is therefore constant along the length of the shaft 21 and away from the entry portion of the groove which is flared to facilitate insertion of the key.

A second side 27b of the shaft 21 is identical to the first side 27a rotated by 180 degrees about the longitudinal axis of the shaft 21. A 180 degree rotation of the shaft about its longitudinal axis therefore leaves the shaft apparently unchanged (i.e. the shaft has 180 degrees rotational symmetry) , and as such, the key blade 19 is reversible . With reference particularly to Figures 3a, 4 and 5, when the key blade 19 is inserted into the opening 9 of the tumbler 7 at the 7th position P7, the first operating edge 23a of the first side 27a of the key blade contacts the face 11a of the formation 11 on the tumbler 7. The first operating edge 23a is so shaped that upon insertion of the key blade 19 fully into the plug 1, that insertion being a specific distance D, the tumbler 7 at the position P7 is pushed upwards from the first locking position to the second releasing position.

The profile of the first operating edge 23a is such that when the key blade 19 is inserted this specific distance D, the key blade also contacts the face 11a of the formation on the side edge 13 of the other downwardly biased tumblers (i.e. those at the 3rd, 4th and 8th positions) and pushes them upwards from the first locking position to the second releasing position. In addition, the first operating edge 23a on the second side 27b of the key blade 19 contacts face lib on the upwardly biased tumblers which have a formation on the opposing side edge (i.e. those at the 1st, 2nd and 5th positions of Figure 2) . The profile of the first operating edge is such that these tumblers are pressed downwards into the second releasing position.

With reference particularly to Figures 3b, 4 and 5, when the key blade 19 is inserted the specific distance D into the opening 9 of the tumbler 7, the second operating edge 23b of the first side 27a of the key blade contacts the face lib of the formation 11 on the upwardly biased tumbler 7 in the 6th position P6. The second operating edge 23b of the key blade is so shaped that the tumbler 7 is pressed downwards from the first locking position to the second releasing position. Thus, it can be seen that the above-described cylinder tumbler lock mechanism includes a first tumbler (the tumbler at position P7) movable in a first direction from the first locking position to the second releasing position and a second tumbler (the tumbler at position P6) movable in a second direction, opposite to the first direction, from the first locking position to the second releasing position. These first and second tumblers have a formation 11 on a side edge 13 of the opening 9 for engagement with a side of a key inserted through the opening. In contrast to the prior art however, the formation 11 on the first tumbler at position P7 and shown in Fig. 3a is on a first side edge for engaging a first side 27a of a key inserted through the opening 9 and the formation 11 on the second tumbler at position P6 and shown in Fig. 3b is also on a first side edge of the tumbler for engaging said first side 27a of a key inserted through the opening.

The blade 19 of the key, not only includes the first operating edge 23a which is suitable for abutting a formation 11 on a side edge 13 of a first tumbler in the lock mechanism, but in contrast to the prior art, also includes the second operating edge 23b suitable for abutting a formation 11 on a side edge 13 of a second tumbler in the lock mechanism.

Since the formations 11 on the tumblers 7 in the 6th and 7th positions engage the same side of the key blade, it is difficult for a picking tool to manipulate the tumblers 7 from the first position to the second position. In addition, the formation 11 on the tumbler in the 6th position obscures the formation on the oppositely-sprung tumbler in the 7th position, when viewed from the end of the plug through which the key is inserted, thereby making the lock mechanism more difficult to pick.

In order to form the grooves 25 on the sides of the key blade 19, a novel cutting technique is adopted with the groove being formed in two cutting strokes: in a first cutting stroke the cutter forms the operating edge 23a by being driven along a path from beyond the free end of the blade 19 into the blade with transverse movement of the cutter being controlled to create the desired profile on the operating edge 23a. Once the cutter reaches the innermost end of the groove, it is then driven in the reverse direction with transverse movement of the cutter being controlled to create the desired profile on the operating edge 23b. Once the cutter has reached the open end of the groove 25, the cutting of the groove with different profiles on each operating edge is complete. The groove on the other side of the blade can be cut in the same way either simultaneously with the first side by using a second cutter or subsequently using the same cutter.

It will be appreciated that various modifications may be made to the above-described embodiment of the invention, without departing from the spirit of the invention. For example, more, or all, of the formations on the tumblers in the cylinder tumbler lock mechanism may be arranged to engage the first side of the key. Indeed the key need not have a groove on its second side. It will be understood that reference to particular features by way of their orientation, such as the upper surface on the plug, should be interpreted relative to the orientation shown in the corresponding Figure (s). Similarly, it will be understood that reference to particular directions, such as downwardly with regard to the tumbler biasing, should also be interpreted relative to the orientation shown in the corresponding Figure (s) . In use, the lock may have any appropriate orientation suitable to its particular application.

Claims

1. A cylinder tumbler lock mechanism comprising a plug rotatably mounted in a housing , the plug including a row of slots formed therein, each slot extending in a direction transverse to the length of the row and containing a tumbler having an opening therethrough for allowing insertion of a key into the plug, the tumbler being slidably mounted in the slot and movable between a first locking position in which one end of the tumbler projects out of an open end of the slot and a second releasing position in which the end of the tumbler is located within the slot, the tumbler being resiliently biased into the first locking position and including a formation on a side edge of the opening for engagement with a side of a key inserted through the opening, wherein the tumblers include a first tumbler movable in a first direction from the first locking position to the second releasing position and a second tumbler movable in a second direction, opposite to the first direction, from the first locking position to the second releasing position, the formation on the first tumbler being on a first side edge for engaging a first side of a key inserted through the opening and the formation on the second tumbler being on a first side edge of the tumbler for also engaging said first side of a key inserted through the opening.

2. A lock mechanism according to claim 1, wherein at least part of the formation on the second tumbler is obscured by the formation on the first tumbler, when viewed in the direction of insertion of the key.

3. A lock mechanism according to claim 2, wherein there are at least three tumblers and the first and second tumblers are adjacent to one another.

4. A lock mechanism according to any preceding claim, wherein the second direction is offset from the first direction by 180 degrees.

5. A lock mechanism according to any preceding claim, wherein the openings in the tumbler is enclosed on all sides by parts of the tumbler.

6. A lock mechanism according to any preceding claim and a key for inserting through the openings in the tumblers.

7. A lock mechanism according to claim 6, wherein the key comprises a shaft including a first operating edge and a second operating edge, the first operating edge and the second operating edge form opposing edges of a groove extending along a side of the shaft, the first operating edge is suitable for abutting the formation on the side edge of the first tumbler, and the second operating edge is suitable for abutting the formation on the side edge of the second tumbler.

8. A lock mechanism according to claim 7, wherein the distance between the first operating edge and the second operating edge at a first location along the shaft is less than the distance between the first operating edge and the second operating edge at a second location along the shaft.

9. A lock mechanism according to claim 7 or 8, wherein the first operating edge has an undulating profile.

10. A lock mechanism according to any one of claims 7 to 9, wherein the second operating edge has an undulating profile.

11. A lock mechanism according to any one of claims 7 to 10, wherein the width of the groove measured between the opposite operating edges varies along the shaft.

12. A lock mechanism according to any one of claims 7 to 11, wherein a second side of the shaft matches the first side rotated by 180 degrees about the longitudinal axis of the shaft.

13. A key suitable for use in a cylinder tumbler lock mechanism according to any preceding claim, the key comprising a shaft including a first operating edge and a second operating edge, wherein the first operating edge and the second operating edge form opposing edges of a groove extending along a side of the shaft, and the first operating edge is suitable for abutting the formation on the side edge of the first tumbler, and the second operating edge is suitable for abutting the formation on the side edge of the second tumbler.

14. A key according to claim 13, wherein the distance between the first operating edge and the second operating edge at a first location along the shaft is less than the distance between the first operating edge and the second operating edge at a second location along the shaft.

15. A key according to claim 13 or 14, wherein the first operating edge has an undulating profile.

16. A key according to any one of claims 13 to 15, wherein the second operating edge has an undulating profile.

17. A key according to any one of claims 13 to 16, wherein the width of the groove measured between the opposite operating edges varies along the shaft.

18. A key according to any one of claims 13 to 17, wherein a second side of the shaft matches the first side rotated by 180° about the longitudinal axis of the shaft.

19. A key for use in a lock mechanism, the key comprising a shaft including a first operating edge and a second operating edge, wherein the first operating edge and the second operating edge form opposing edges of a groove extending along a side of the shaft.

20. A key according to claim 19, wherein the width of the groove measured between the opposite operating edges varies along the shaft.

21. A key according to claim 19 or claim 20, wherein the first operating edge has an undulating profile.

22. A key according to any one of claims 19 to 21, wherein the second operating edge has an undulating profile.

23. A key according to any one of claims 19 to 22, wherein a second side of the shaft matches the first side rotated by 180 degrees about the longitudinal axis of the shaft.

24. A key according to any one of claims 19 to 23, wherein the distance between the first operating edge and the second operating edge at a first location along the shaft for abutting a formation on the side edge of a first tumbler is less than the distance between the first operating edge and the second operating edge at a second location along the shaft for abutting a formation on the side edge of a second tumbler.

25. A key according to claim 24, wherein the distance between the first operating edge and the second operating edge at a third location along the shaft for abutting a formation on the side edge of a third tumbler is different from the distances between the first operating edge and the second operating edge at the first and second locations along the shaft.

26. A cylinder tumbler lock mechanism comprising a key according to any one of claims 19 to 25, a plug rotatably mounted in a housing , the plug including a row of slots formed therein, each slot extending in a direction transverse to the length of the row and containing a tumbler having an opening therethrough for allowing insertion of a key into the plug, the tumbler being slidably mounted in the slot and movable between a first locking position in which one end of the tumbler projects out of an open end of the slot and a second releasing position in which the end of the tumbler is located within the slot, the tumbler being resiliently biased into the first locking position and including a formation on a side edge of the opening for engagement with one of the operating edges of the key when, in use, the key is inserted through the opening .

27. A lock mechanism according to claim 26, wherein the tumblers include a first tumbler movable in a first direction from the first locking position to the second releasing position and a second tumbler movable in a second direction, opposite to the first direction, from the first locking position to the second releasing position, the formation on the first tumbler being on a first side edge for engaging a first side of the key inserted through the opening and the formation on the second tumbler being on a first side edge of the tumbler for also engaging said first side of the key inserted through the opening.

28. A method of cutting a key according to any of claims 13 to 25, in which a cutter is moved along the path of the groove in a first pattern of movement to form the first operating edge and is subsequently moved along the path of the groove in a second pattern of movement to form the second operating edge .

29. A method according to claim 28, in which the cutter is moved in a first direction to form the first operating edge and is subsequently moved in a second direction opposite to the first to form the second operating edge.