GB2295848A - Locks and keys - Google Patents

Abstract

A lever lock has a thrower 17 with a barrel 22 journalled in the lock case. The barrel has a longitudinal passageway opening through a longitudinal slot 25 in the direction of the key bit 29. A portion 24B of the cross-section of the barrel passageway is wider than the slot 25 and offset with respect to the axis of rotation of the barrel X in the direction away from the slot. The cross-section of the pin of the correct key has a complementary formation with a wider portion 30B and a narrower portion 30A (Fig 7). The offset passageway portion 24B means that if an attempt is made to insert a conventional key with its circular pin cut down to the width of that portion (Fig 8), it will be displaced from the axis of rotation X and underlift the levers 10. <IMAGE>

Description

Locks and Kevs The present invention relates to lever locks and keys therefor.

By "lever locks" we mean locks of the well-known kind in which the key-recognition mechanism comprises a plurality of pivoted or slidable tumblers or detainers (termed "levers") each having a surface, usually of arcuate form (termed the "belly"), which is swept by a respective step of a bitted key when the latter is turned in the lock, whereby to shift the levers to selected relative positions in which they collectively permit retraction of the bolt or other such locking member from its locking to its unlocking position.

The keys for such locks typically comprise a bow (i.e.

handle) portion joined by a shank to the bit. In the case of a so-called pin key, the operative end of the key has a portion formed as an extension of the shank (the "pin"), from which the bit proper extends in a radial direction. The pins of such keys are almost invariably of circular cross-section although certain other forms are disclosed in GB-A-883499, GB-A-1492552, EP-A-0297063 and DE-C-4005459.

It is often the case that a lever lock includes a separate member borne rotationally within the casing which is arranged to turn together with the key. This turning member may have the function of a thrower which engages the bolt to extend or retract the same while the key bit keeps the levers lifted. Alternatively or additionally it may comprise a curtain member the purpose of which is to block access through the leg portion of the keyhole whenever it is turned away from the keyinsertion position, as an anti-manipulation measure.In any case, this turning member typically comprises a partcylindrical barrel portion journalled at each end in the lock casing, having an internal passageway to receive the pin of the key, coaxially in the case of a circular pin, and a longitudinal slot opening from this passageway from which the key bit extends and by which turning of the key is transmitted to the turning member.

The present invention resides in a lever lock having a turning member borne for rotation within the casing of the lock; the turning member comprising a barrel having an internal passageway to receive the pin of a corresponding key and a longitudinal slot opening from said passageway in the direction of the bit of the key; the cross-section of said passageway comprising at least a portion having a width greater than the width of said slot, which portion is offset with respect to the axis of rotation of the barrel in the direction away from said slot. In the context of the present invention the "pin" of a key is taken to be the whole of that part of its operative end which is adapted to be inserted into the passageway of the turning member and from which the bit proper extends.

In one preferred embodiment the cross-section of the passageway comprises first and second flat-sided portions respectively of lesser and greater width; the first portion opening through said slot and being of a corresponding width; the second portion joining the first portion and being offset with respect to the axis of rotation of the barrel in the direction away from said slot. However, many variations in the form of the passageway cross-section are possible within the scope of the invention to achieve the specified offset character.

The invention also resides per se in a turning member for use in such a lock, in a key comprising a pin at least part of the length of which has a cross-section complementary to said passageway, and in a blank for such a key.

An advantage of the special cross-section of the barrel passageway and corresponding pin in a lock and key according to the invention is that, without access to a key blank of the correct cross-section it is not readily possible to cut a key which will open the lock. By restricting the availability of such blanks, therefore, it is possible to control the availability of duplicate keys. In particular, if an attempt is made to cut down or "skeletonise" the circular pin portion of a conventional lever key blank to fit the barrel passageway it will still make operation of the lock difficult or impossible, as will become apparent from the following particular description.

More particularly, the cross-section of the barrel passageway in a lock according to the invention can be characterised as such that if a conventional key - that is to say a key comprising a circular cross-section pin portion of a diameter not less than the width of said offset portion of the passageway and a bit cut to correctly shift the levers if that pin portion is turned coaxially with the barrel - is inserted into the passageway, if need be after removing the minimum amount of material from the pin sufficient to permit such insertion, and is turned with the barrel, then the bit will be mislocated with respect to the levers such that the levers are shifted through insufficient distances to permit retraction of the locking member.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates the mechanism of one embodiment of a lever lock in accordance with the invention; Figure 2 is a rear view of the thrower incorporated in the lock of Figure 1; Figure 3 is a section on the line III-III through the thrower of Figure 2; Figure 4 is a section on the line IV-IV through the thrower of Figure 3; Figure 5 is a side view of a blank for the key to be used with the lock of Figure 1; Figure 6 is an isometric view of the bit end of the key blank of Figure 5; Figure 7 is a section on the line VII-VII in Figure 3 through the barrel portion of the thrower of the lock with the proper key inserted;; Figures 8 and 9 are views similar to Figure 7 with incorrect keys made by modifying a conventional blank inserted in the barrel; and Figures 10 to 16 are views similar to Figure 7 illustrating alternative cross-sections for the key pin and barrel passageway.

Referring to Figure 1, this illustrates the mechanism of a lever lock in accordance with one embodiment of the invention, being a modified version of the mortice deadlock currently marketed by the Applicants under the designation 3G114. It comprises a casing of which the main part is formed by a plate 1 having turned-up edges 2 and an attached forend 3, and which is normally closed by a plate-like cap located over the ends of posts 4 upstanding from the plate 1 and fixed by screws passing into threaded bosses 5 likewise upstanding from the plate 1, the cap being removed in Figure 1 for ease of illustration. A deadbolt 6 is borne for extension and retraction between locking and unlocking positions, having a head portion 7 guided through the forend 3 and a tail portion 8 guided by a track 9 formed in the plate 1.

A pack of, say, five levers 10 are pivoted on a pin 11 upstanding from the plate 1 and are biased in the anticlockwise sense (as viewed) by respective leaf springs 12. Each lever 10 is formed with a pair of pockets 13A,13B separated by a respective gate 14 and in the illustrated locking condition a stump 15 upstanding from the bolt tail 8 is trapped in the forward pockets 13A of the levers, thereby blocking retraction of the bolt.

The lock also comprises a thrower 17 journalled in the casing.

In order to retract the bolt 6 from the illustrated position a correct key is inserted into the thrower 17 and given one complete turn in the clockwise sense (as viewed). As the key turns, respective steps on its bit sweep the bellies 16 of respective levers to lift the same by the correct heights to align their respective gates 14 with the bolt stump 15. The key also of course turns the thrower 17, which has on its rear side a rib 18 to engage in a talon form 19 in the bolt tail 8. While the levers 10 remain lifted by the turning key the thrower rib 18 retracts the bolt 6 so that its stump 15 passes through the aligned lever gates 14 from pockets 13A to pockets 13B.As the key completes its revolution and disengages from the lever bellies 16 the levers are allowed to fall once more, to leave the stump 15 trapped in the rearward pockets 13B and the bolt consequently blocked against extension. Subsequent extension of the bolt 6 is of course the reverse of this action, with the key turning anticlockwise (as viewed).

The thrower 17 also incorporates a curtain 20 which blocks access through the leg portion of the keyhole provided in the plate 1 whenever it is turned away from the illustrated key-insertion position. A detent spring 21 also acts on the curtain 20 so as normally to keep the whole thrower 17 in the key-insertion position.

As thus far described, the operation of this lock is conventional. The form of the thrower 17 is, however, modified in accordance with the invention and this will now be more fully described with reference to Figures 24.

As shown in those Figures, the thrower 17 comprises in addition to the rib 18 and the curtain 20 a barrel portion 22. The external profile of the barrel 22 is generally cylindrical, with the end portions of the barrel being of reduced external diameter as indicated at 23 where they are journalled respectively in the plate 1 and the cap of the lock casing. The interior of this barrel is formed as a flat-sided passageway of stepped width, thus having a narrower section 24A and a wider section 24B. The narrower passageway section 24A opens through a longitudinal slot 25 throughout the length of the main portion of the barrel, and joins a slot 25A through the curtain 20. The wider passageway section 24B is separated from the slot 25 by the section 24A and is offset with respect to the rotational axis of the thrower in the direction away from that slot.That is to say the centre of area (centroid) of the section 24B is located above the axis X in the sense as viewed in Figure 2.

The form of this thrower 17 thus differs from the conventional thrower in terms of the profile of its internal passageway 24A,24B (which comprises a cylindrical section coaxial with the rotational axis in the conventional thrower).

The form of a blank from which keys for the illustrated lock can be cut will now be described with reference to Figures 5 and 6.

The blank 26 illustrated in those Figures has conventional bow 27, shank 28 and bit 29 portions, but differs from a conventional blank in terms of the configuration of its pin region. That is to say the pin is not of circular cross-section but is flat-sided and of stepped-width, thus having a narrower section 30A dimensioned to fit within section 24A of the thrower passageway and a wider section 30B dimensioned to fit within section 24B of the thrower passageway, the pin section 30A joining and being of the same width as the bit proper 29.

In use of a key cut from a blank 26, its bitted end is inserted into the thrower, from either side of the lock, with the pin sections 30A and 30B being received respectively in the passageway sections 24A and 24B of the thrower barrel 22, and the bit 29 extending away from the slot 25. The depth of insertion is determined by the abutment with the respective barrel end 23 of the end face 31A of a collar 31 formed at the end of the key shank 28. The inserted condition of the key with respect to the barrel 22 is shown in Figure 7. It is observed here that the key pin 30A/30B need not be of constant cross-section throughout the whole of its length. Portions may be relieved if so desired so long as enough of the pin is of a complementary cross-section to the passageway 24A/24B to correctly locate the key for operation in the lock.

Also superimposed on Figure 7 at 32 is the internal diameter of a conventional thrower barrel, from which it will be appreciated that a key pin configured to fit that barrel could not enter the passageway of barrel 22 and vice versa. Moreover a key cut from a conventional blank with a pin to fit the diameter 32, even if its bit was ostensibly cut correctly, could not be modified by cutting down its pin to satisfactorily operate the lock, as will be explained with reference to Figures 8 and 9.

In Figure 8 it is assumed that the sides of the circular pin portion 30' of a conventional blank have been filed so that the pin will fit within the passageway section 24B of the barrel 2. It may also be necessary to file down the top surface of the collar of the conventional blank (corresponding to 31) to achieve full insertion of the pin without the collar fouling the lock casing. Due to the offset location of the section 24B, however, this results in the central axis of the pin portion 30' (corresponding to the rotational axis of the conventional thrower) being offset by the dimension h from the rotational axis x of the barrel. The bit 29' of the key has accordingly also been drawn in towards the barrel by this dimension so that as it is turned in the lock it will under-lift the levers 10 and the bolt cannot be shifted.If it is attempted to overcome this problem by removing more metal from the underside of the pin portion 30' (not an easy task), so that its axis can be located on the rotational axis of the barrel, then the situation depicted in Figure 9 will pertain. That is to say there is now a free space 33 between the pin 30' and the top end of passageway section 24B. As the key is now turned to contact the levers, therefore, it will tend to be displaced laterally in the barrel. Only if the user can keep the pin pressed against the step between sections 24A and 24B as it is turned, against the reaction force of the lever springs 12, will it be possible to lift the levers correctly, but this will make for an extremely awkward manipulation.

Turning to Figures 10 to 16 these illustrate, in views similar to Figure 7, a range of alternative passageway and pin cross-sections which may be employed in locks and keys according to the invention. In each case the passageway in the barrel has a first section of narrower width opening through a longitudinal slot in the direction of the key bit, with the remainder of the passageway being of greater width and offset with respect to the axis of rotation in the direction away from the slot, and the key pin cross-section is of complementary form.

In all of the embodiments described herein the narrower (or narrowest) section of the key pin is of the same width as the bit proper and can be regarded as an inward extension thereof. However, this need not necessarily be the case, and in other embodiments there may be a change of width at the junction between the bit proper and the adjacent section of the pin. The operative end of the key may also be bulleted if desired in accordance with conventional practice.

Claims (18)

1. A lever lock having a turning member borne for rotation within the casing of the lock; the turning member comprising a barrel having an internal passageway to receive the pin of a corresponding key and a longitudinal slot opening from said passageway in the direction of the bit of the key; the cross-section of said passageway comprising at least a portion having a width greater than the width of said slot, which portion is offset with respect to the axis of rotation of the barrel in the direction away from said slot.

2. A lock according to claim 1 wherein the crosssection of said passageway comprises a first portion opening through said slot and a second portion joining said first portion and having a width greater than said first portion, said second portion being offset as aforesaid.

3. A lock according to claim 2 wherein said first and second portions each have substantially flat and parallel sides.

4. A lock according to claim 2 wherein the width of said second portion diverges the direction away from said slot.

5. A lock according to claim 2 wherein the crosssection of said passageway is generally 'T' shaped.

6. A lock according to claim 2 wherein the crosssection of said second portion is of stepped width increasing in the direction away from said slot.

7. A lock according to any preceding claim wherein the cross-section of said passageway is such that if a key, which key comprises a circular cross-section pin portion of a diameter not less than the width of said offset portion of the passageway and a bit cut to correctly shift the levers if that pin portion is turned coaxially with the barrel, is inserted into said passageway, if need be after removing the minimum amount of material from the pin sufficient to permit such insertion, and is turned with the barrel, then the bit will be mislocated with respect to the levers such that the levers are shifted through insufficient distances to permit retraction of the locking member.

8. A lock substantially as hereinbefore described with reference to Figures 1 to 4 and 7 to 9, or any one of Figures 10 to 16 of the accompanying drawings.

9. A turning member for use in a lock according to any preceding claim.

10. A key for a lock according to any preceding claim, comprising a pin at least part of the length of which has a cross-section complementary to said passageway.

11. A key for a lever lock comprising a bow, a shank, a pin and a bit; the cross-section of said pin comprising, for at least part of its length, at least a portion having a width greater than the width of the bit, which portion is offset with respect to the intended axis of rotation of the key in the direction away from said bit.

12. A key according to claim 11 wherein the crosssection of said pin comprises, for at least part of its length, a first portion joining said bit and a second portion joining said first portion and having a width greater than said first portion, said second portion being offset as aforesaid.

13. A key according to claim 12 wherein said first and second portions each have substantially flat and parallel sides.

14. A key according to claim 12 wherein the width of said second portion diverges in the direction away from said bit.

15. A key according to claim 12 wherein the crosssection of said pin, for at least part of its length, is generally 'T' shaped.

16. A key according to claim 12 wherein the crosssection of said second portion is of stepped width increasing in the direction away from said slot.

17. A key substantially as hereinbefore described with reference to Figures 5 to 7 or any one of Figures 10 to 16 of the accompanying drawings.

18. A blank for a key according to any one of claims 10 to 17.