GB2314582A

GB2314582A - Key-operated locks and lock keys

Info

Publication number: GB2314582A
Application number: GB9704763A
Authority: GB
Inventors: Brian E Cowper
Original assignee: Banham Patent Locks Ltd
Current assignee: Banham Patent Locks Ltd
Priority date: 1996-06-27
Filing date: 1997-03-07
Publication date: 1998-01-07
Anticipated expiration: 2017-03-07
Also published as: GB2314582B; GB9704763D0; GB9613465D0

Abstract

A cylinder pin tumbler lock has, in addition to the conventional pin tumbler mechanism, an obturator pin (24) mounted in the cylindrical plug (6) of the lock and movable between a blocking position in which an outer end projects into an opening (26) in the lock body, and a release position in which an inner end projects into a slot (8) in the plug which receives the lock key. The pin is located in the slot entry end region between the tumbler pin mechanism and the end face of the plug, and opposite a projecting ward (30) in the plug slot. The appropriate key thus has bittings (18) for the pin tumbler mechanism and an opening (28) to receive the obturator pin. A blank for the key has the opening (28) substantially in the middle of the width of the key blade and opposite a groove (32) mating with the plug slot ward (30). The opening (28) is immediately adjacent the locating ear (10d) of the key that limits its insertion into the plug.

Description

KEY-OPERATED LOCKS AND LOCK KEYS This invention relates to cylinder pin tumbler locks and to keys for such locks.

Among the reasons for the wide use of cylinder pin tumbler locks is their ability to offer, at reasonable cost in a compact form of lock, a large number of differs and master-keying facilities. However, the means for cutting the bits of pin tumbler lock keys are widely available. It is usually impossible therefore to prevent the unauthorised copying of keys for designs of cylinder pin tumbler lock that are available commercially. This is an obvious disadvantage for members of the public relying on such locks for security.

According to one aspect of the present invention, there is provided a cylinder pin tumbler lock having a body in which a pin tumbler mechanism is operable by a key, a cylindrical plug being rotatable in the body about its central axis, a generally oblong cross-section keyway or slot extending axially along the plug from an entry end region of the plug into which the key blade is received, guide holes for the pins of the tumbler mechanism opening into said slot whereby bits cut on an edge of the key inserted through said entry region can be aligned with the pins to hold them at positions in which they permit said relative rotation between the plug and the lock body, at least a first major side of the oblong slot comprising at least one projecting ward for co-operation with a groove in a side face of the key blade, an obturator pin mounted in the cylindrical plug having an outer end removably held in or being displaceable into a locating opening in the lock body to block the rotation of the cylindrical plug relative to the body, the inner end of the pin projecting into the key slot when said one end is free of said locating opening, whereby said pin assumes a release position when said end is located in an opening in an appropriately formed key blade inserted into the slot and allows the plug to be rotated by the key, said pin inner end being located in the slot entry end region between the tumbler pins and the entry end face of the plug and protruding into a side of the slot opposite said first major side, the pin inner end at least partially overlapping the location of said projecting ward in said first side in the direction of the width of the major sides of the keyway or slot crosssection.

The obturator pin is preferably allowed to float freely, the contact faces between the pin and the openings permitting the pin to be cammed to the blocking and release positions. Alternatively, however, the pin maybe springbiased to either of its positions of displacement.

In another aspect of the invention, a key blank is provided from which a key can be cut for such a lock, the key blank comprising a head portion and an elongate key blade extending from said head portion for insertion into a rotatable plug of the lock, the key blade having opposite first and second main side faces and opposite first and second side edges, at least one said side edge being arranged to be formed with a series of bits for engagement with locking pins of the pin tumbler mechanism in the lock plug whereby to permit rotation of the plug in the lock, an opening being provided in a first of said side faces of the key blade for receiving the end of an obturator pin mounted in the plug of the lock, said opening being located in a region of the length of the blade immediately adjacent the head portion and being spaced from said opposite first and second side edges, a second side face of the key blade opposite said first side face being formed with at least one longitudinal groove extending longitudinally along the blade over the extent of the bits for cooperation with a projecting ward of the lock, said opening at least partially overlapping the location of said longitudinal groove in the direction of the width of the key blade side faces. Said opening may be in the form of a blind recess terminating short of the second side face and the associated groove, or it may be in the form of a throughopening extending from said first side face into the associated groove.

It is a characteristic of pin tumbler locks that the tumbler pins are spaced from the entry end of the lock plug through which the key is inserted. By referring to the location of said key blade opening "immediately adjacent the head portion" of the key it is intended to indicate that it will coincide with the entry end region of the key slot of a lock between the tumbler pins and the entry end face. of the lock plug and so be beyond the portion of the key blade length that engages the pin tumblers. It is customary to form keys for cylinder pin tumbler locks with a bow or ear on the inner end of the key blade to limit insertion of the blade into the lock and the opening is then located between the bow and the innermost of the bits cut in the blade.

By providing at least one opening in this manner for cooperation with an obturator pin of the lock, it can be made impossible to produce an unauthorised copy of the key by milling or broaching an additional groove along the blade to form a hollow in the blade equivalent to said opening.

Preferably, the opening is located substantially centrally between opposite side edges of the key blade.

For additional security, the key blank may have a plurality of said openings for respective obturator pins, advantageously each partially overlapping a respective ward groove in the blade, but it is only required that at least one of said openings is located immediately adjacent the head portion as aforesaid, although it is possible to provide two openings in opposite side faces of the blade at substantially the same location in the longitudinal direction of the blade. If, however, a second or further opening is provided, it is preferably located so that in the finished key it is between two bits cut in the key blade edge.

In an alternative configuration, it is possible to provide a single through opening in the key blank to receive the inner ends of opposed obturator pins.

Examples of the invention will now be described with reference to the accompanying diagrammatic drawings in which: Fig. 1 is a simplified and exploded isometric view of a key and lock according to the invention, Fig. 2 is a transverse cross-section of the lock in Fig. 1 showing the cooperation of the key and obturator pin as the lock is turned, Fig. 3 is a view similar to that in Fig. 2 but shows the position of the obturator pin when an incorrect key is inserted, Fig. 4 is a detail view of the key showing the recess near the key head portion, Fig. 5 is a transverse cross-sectional view of an alternative form of lock according to the invention, with key inserted, Figs. 6 and 7 are cross-sectional views similar to Fig. 5 of two further embodiments of the invention, Figs. 8 to 10 illustrate an alternative key according to the invention, with two spaced recesses, Figs.

9 and 10 being sectional views on the lines A-A and B-B respectively in Fig. 8, and Fig. 11 illustrates another key according to the invention with some preferred dimensions.

Fig. 1 of the drawings shows some of the main components of a cylinder pin tumbler lock according to the invention. The-lock body 2 has a bore 4 in which a cylindrical plug 6 is held to rotate concentrically within the bore. An oblong, generally rectangular slot 8 extends axially the length of the plug to receive the blade 10a of a key 10 the back edge of which bears on the wall of the bore 6. A row of transverse bores 12 in the plug 6 open onto the other edge of the slot 8 and in them slide tumbler pins 14 of selected lengths to which the bitting 18 on the front edge of the key blade is matched. The drawing does not show the remainder of the pin tumbler mechanism contained in the lock body and urging the pins against the key bitting but this, and the manner in which the tumbler pins and key bitting cooperate, canoe entirely conventionally arranged and need not be described further.

The plug 6 has a further transverse bore 20 located in an entry end region between the plug entry end flange 22 and the first of the bit bores 12. An obturator pin 24 is slidably located in the bore 20 but is longer than the bore so that it either projects with its outer end into an opening 26 in the inner wall of the body or with its inner end into an opening 28 in the key blade 10a.

As can be more clearly seen in Fig. 2, the generally rectangular key slot 8 has a series of axial projections or wards 30 running along its length, these being staggered relative to each other on opposite sides of the slot. The key has a complementary series of grooves 32 in its opposite main side faces 10b.

As Fig. 2 also shows more clearly, the obturator pin 24 has a stepped body 36 and conically shaped inner and outer ends 38,40 the tips of which are rounded. The plug bore 20 in which the pin slides has a complementary step 42 to limit the inward movement of the pin. The body opening 26 receiving the outer end 40 of the pin is in the form of a recess having an arcuate transverse cross-section, the opposite ends of which are inclined to the circumferential direction so that, in cooperation with the tapered outer end 40 of the pin, a camming action is exerted on the pin when the plug 6 rotates in the body 2. Fig. 2 shows how, when the appropriate key is used, the camming action drives the pin 24 out of the recess 26 and into the key blade opening 28 which has the form of a conically tapered form and in this instance opens into the opposite face of the blade.

Although Fig. 2 shows both the openings 26,28 and the ends 38,40 of the pin 24 with inclined faces, it will be understood that the camming action can be obtained also if only one of each cooperating pair of faces is inclined.

Also, inclination of the key blade opening walls to give a camming action requires only that the portion further from the head 10c of the key is inclined. Conveniently, however, the obturator pin is rotationally symmetrical about its central axis so that it can turn freely to spread the wear on the ends 38,40.

As will be clear from Fig. 2, the camming action between the body recess 26 and the obturator pin 24 allows the plug 6 to be freely turned (assuming the key bitting 18 matches the tumbler pin mechanism) to operate the lock because it drives the pin completely out of the body recess 26. In the absence of the opening 28 in the key blade however, as is shown in Fig. 3 by the blade 10x, the obturator pin 24 blocks rotation of the plug because it cannot move out of the body recess when an attempt is made to turn the key.

Fig. 4 shows more clearly the preferred location of the opening or recess 28. It lies centrally of the width of the key blank. It is also in the narrow region between the first bit 18a and the bow or ear 10d that defines the junction between the head and the blade.

Because it is in a central region of the width of the blade, it would not be practical to form an alternative clearance space for the obturator pin by cutting a slot to this position from either edge of the blade because the key would be unduly weakened thereby. Furthermore, because it is immediately adjacent the head 10c of the key and a ward groove 32 runs along the blade in lateral coincidence with the opening 28 it is impossible to mill or broach an additional slot along the key blade to provide clearance for the obturator pin.

In the example shown in Fig. 5 the lock plug 52 carries an obturator pin 54 which has a conical outer end 56 and which is biased to its locking state into a recess or blind opening 58 of the lock body 60 by a spring 62.

The pin can still cam against the inner edge of the opening in the way already described when an appropriate key 10 is inserted and the opening 64 in the key blade is registered with the cylindrical inner end 66 of the pin. Because of the spring bias, there need be no camming action between the pin and the opening 64, which allows more variation of the shape of the aperture 64, a cylindrical form of aperture being illustrated. The flat inner end 66 of the pin 54 also allows for more variation in the location of the opening 64 in the key blade while still making it impractical to produce an equivalent hollow by forming a groove along the length of the blade due to the proximity of a ward groove. It may even be possible for the pin opening to overlap more than one groove on the opposite face of the key blade.

In the example of Fig. 6, the locking pin 72 in the plug 4 is biased inwards, towards the key blade, by spring 76. Its inner end 78 is conically shaped so that it can be cammed back into the opening 80 (shown as a through opening in this example) in the body 82 as the key 10 is inserted in the plug slot and be urged by the spring 76 into the complementary opening 84 in the key blade as soon as the key is fully inserted. Should a key lacking the recess be inserted, the pin 72 is similarly cammed back but remains engaged the opening 80 when the key is fully inserted so that the plug cannot be turned.

Although not so shown in Fig. 6, this arrangement allows the obturator pin to be placed further from a diametrical centre line of the lock plug because the pin does not have to be cammed away from the lock body, so there is more freedom for the design of other features of the lock. By positioning the pin below the deepest key bits there is greater scope for varying the position of the pin axially of the lock body because the opening can be kept clear of the bitting profile without limiting the number of differs available.

In the lock shown in Fig. 7, there are two obturator pins 86,88, one on each side of the slot 8 in the plug 90. They can be freely floating or spring-loaded.

The drawing shows one floating pin 86 and one pin 88 urged outwards by spring 92. Respective openings 94,96 in the body 98 for the pins 86,88 are adapted to the form of the pin outer ends. The figure also shows that it is sufficient for only one of the cooperating surfaces to be inclined for a camming action, as in the case of the outer end of the pin 88 and the body opening 96. It is preferred, however not to form a through-opening in the body for a pin immediately adjacent the key head portion.

The drawing also shows respective openings 100,102 for the two pins in the key 104 but if they are directly opposite each other a single opening can be formed in the key to receive them.

Figs. 8 to 10 illustrate some further preferred locations for the openings in the key blade. The first (see in particular Fig. 9) shows an opening 110 on the diametrical centre line of the plug, immediately adjacent the head of the key between the key bow and the bitting, at the highest position in relation to the first bit and opposite ward groove 112. The other opening 114 (see in particular Fig. 10) is below the plug centre line, in the middle of the height of the blade in the manner of the embodiment in Figs. 1-4, opposite the ward groove 116.

Fig. 8 illustrates how the opening 114 might fit between two bits cut to the deepest limit.

Provided the integrity of the bitting is maintained, openings can be located at other positions on the key blade and may extend partly or wholly through the key blade cross-section. The shapes of the openings and the cooperating ends of the pins can also be chosen to give a more secure arrangement and, of course, the shapes of the openings and pins can be varied in such a way as to provide a further series of differs.

In Fig. 11 some of the preferred dimensional relationships of a key according to the invention are shown. For simplicity, the ward grooves are not illustrated but they can be arranged in the manner shown in Figs. 8-10, with the opening 114 in one face of the blade coincident with a groove in the opposite face. The centre of the opening 114 should not be substantially more than 3mm from the datum face 124 of the bow or ear 10d that abuts the lock plug 6 when the key is fully inserted into the lock. If the width of the blade blank is 8.5mm, the central location of the opening 114 places its centre 4.25mm from either side edge.

The bits 18 cut in key blade at a pitch of 4.2mm have a range of differs extending below the 4.25mm mid depth but the first bit 18a nearest the head at its midpoint some 5mm from the datum face 124 and its depth is therefore limited, the height from the back edge of the blade to the bit preferably not substantially less than 4.8mm. This is because the conventional cutting of a bitting profile, margins are formed sloping at 450 to each side of the bit proper or land on which the tumbler pin seats, and the margin extending toward the key head can overlap the location of the opening if the first bit is too deep. Other of the bits can be cut deeper, eg. to give a minimum height from the back edge of about 3.8mm.

It will be understood also that features illustrated in each embodiment described above can be combined with or substituted for features in other embodiments within the scope of the invention.

Claims

1. A cylinder pin tumbler lock having a body in which a pin tumbler mechanism is operable by a key, (i) a cylindrical plug rotatable in the body about its central axis, (ii) a generally oblong cross-section keyway or slot extending axially within the plug from an entry end region of the plug into which the key blade is received, (iii) guide holes for the pins of the tumbler mechanism opening into said slot whereby bits cut on an edge of the key blade inserted through said entry region can be aligned with the pins to hold them at positions in which they permit said relative rotation between the plug and the lock body, (iv) at least a first major side of the oblong slot comprising at least one projecting ward for cooperation with an axial groove in a side face of the key blade, (v) an obturator pin mounted in the cylindrical plug having an outer end removably held in or being displaceable into a locating opening in the lock body to block the rotation of the cylindrical plug relative to the body, (vi) the inner end of the pin projecting into the key slot when said one end is free of said locating opening, whereby said pin assumes a release position when said end is located in an opening in an appropriately formed key blade~inserted into the slot and allows the plug to be rotated by the key, (vii) said pin inner end being located in the slot entry end region between the tumbler pins and the entry end face of the plug and protruding into a side of the slot opposite said first major side (viii) the pin inner end at least partially overlapping the location of said projecting ward in said first side in the direction of the width of the major sides of the keyway or slot.

2. A lock according to claim 1 wherein said obturator pin is located substantially at the middle of the width of the major sides of the keyway or slot.

3. A lock according to claim 1 or claim 2 wherein the obturator pin is freely slidable in opposite directions with respect to said locating opening by the action of camming means provided by the ends of the pin and the cooperating surfaces of the lock body and key blade engaging said ends.

4. A lock according to claim 1 or claim 2 wherein the obturator pin is resiliently biased to one of said blocking and release positions and has an outer end cooperating with the lock body or an inner end for cooperating with a non-conforming key, respectively, for camming to the other of said positions.

5. A lock according to any one of the preceding claims wherein the obturator pin is located in a substantially diametrically extending aperture in the plug body.

6. A lock according to claim 5 wherein said plug body aperture extends in a substantially normal direction said tumbler mechanism pins.

7. A lock according to any one of the preceding claims wherein at least one further obturator pin is mounted in the cylindrical plug for blocking relative rotation between the plug and the lock body.

8. A lock according to claim 7 wherein there are respective obturator pins on opposite major sides of the keyway or slot.

9. A lock according to claim 8 wherein the opposite major sides of the keyway or slot each have at least one projecting ward said wards having staggered locations relative to each other in the direction of the width of said sides, and the inner end of each said pin overlapping the location of the ward on the side opposite the pin.

10. A lock according to claim 9 wherein one said pin is positioned in the slot entry region and another of said pins is positioned between the locations of two tumbler mechanism pins. with reference to the axial direction of the plug.

11. A lock according to claim 8 wherein said obturator pins are substantially aligned with each other in the direction of the width of said major sides of the keyway or slot.

12. A key comprising at least one opening for use in a lock according to any one of the preceding claims.

13. A key blank for a cylinder pin tumbler lock comprising: (i) a head portion and an elongate key blade extending from said head portion for insertion into a rotatable plug of the lock, (ii) the key blade having opposite first and second side edges at least one of which is arranged to be formed with a series of bits for engagement with locking pins of the pin tumbler mechanism in the lock plug whereby to permit rotation of the plug in the lock, (iii) opposite first and second main side faces of the key blade transverse to said side edges, a first of said side faces being formed with an opening for receiving the end of an obturator pin mounted in the plug of the lock, (iv) said opening being located in a region of the length of the blade immediately adjacent the head portion and being spaced from said opposite first and second side edges, (v) a second side face of the key blade opposite said first side face being formed with at least one groove extending longitudinally along the blade over the extent of the bits for cooperation with a ward projection of the lock, (vi) said opening at least partially overlapping the location of said longitudinal groove in the direction of the width of the key blade main side faces.

14. A key blank according to claim 13 wherein said opening is located substantially centrally between said side edges.

15. A key blank according to any one of claim 13 or claim 14 having at least one further opening for a further obturator pin or pins, the openings being located in said one side face or in opposite side faces.

16. A key blank according to claim 15 wherein said side faces are each formed with at least one said longitudinal groove and at least one said opening is formed in each side face at a position at least partially overlapping the location of said groove in the side face opposite thereto in the direction of the width of the blade side faces.

17. A keblank according to claim 15 having two said recesses located in the opposite side faces of the blade at substantially the same location in the longitudinal direction of the blade.

18. A key blank according to any one of claims 13 to 17 wherein said opening or at least one said opening is formed as a through aperture between said side blade faces.

19. A key blank according to any one of claims 13 to 17 wherein said opening or at least one said opening is formed as a blind recess in its blade side face.

20. A key blank according to 19 wherein said opening is formed with ah inclined face to assist urging the associated obturator pin therefrom by a camming action.

21. A key blank according to any one of claims 13 to 20 wherein said opening or at least one said opening is not substantially more than 3mm from a datum locatable at an end face of the plug.

22. A key cut from a blank according to any one of claims 13 to 21, wherein said opening, or at least one of said openings substantially aligned with a said longitudinal groove, is located in a region of the length of the blade between the bits and the head portion.

23. A key according to claim 22 having a plurality of said openings and at least a further one of said openings is located in a region of the length of the blade between two bits.

24. A key cut from a blank according to any one of claims 13 to 21 wherein the land of the bit nearest said opening or said at least one opening has, in the longitudinal direction of the key blade, its centre not substantially less than 2mm from the centre of a land of the nearest bit to the head of the key.

25. A cylinder pin tumbler lock constructed and arranged for use and operation substantially as described herein with reference to the examples in the accompanying drawings.

26. A key for a cylinder pin tumbler lock constructed and arranged for use and operation substantially as described herein with reference to the examples in the accompanying drawings.

27. A key blank for a key according to claim 26.

28. In combination, a lock according to any one of claims 1 to 11 or 23 in combination with a key according to any one of claims 12, 22 to 24 or 26.