GB2355042A

GB2355042A - Security device

Info

Publication number: GB2355042A
Application number: GB0024473A
Authority: GB
Inventors: Bruce Patrick Mccarthy
Original assignee: Yale Security Products UK Ltd
Current assignee: Security Products UK Ltd
Priority date: 1999-10-08
Filing date: 2000-10-06
Publication date: 2001-04-11
Anticipated expiration: 2020-10-06
Also published as: GB9923698D0; GB0024473D0; GB2355042B

Abstract

A key (10) for a pin tumbler lock (28) has bittings (20,22) in its upper edge, the bittings (20) being for engagement in the normal manner with pins (50) having rounded ends, and the bitting (22) being to receive a pin (54;58) which has a wholly straight side surface (55b). The bitting (22) includes a stop surface (26;60) which is normal to the upper edge surface of the key and engages the straight side surface (55b) when the key is fully inserted into the lock. With this construction 'raking' of the lock is prevented.

Description

2355042 SIF,CURM DEVICE This invention relates to a security device, and

more particularly to a key for a pin tumbler lock.

Current keys which are adapted for use in pin tumbler locks employ a shank having a series of longitudinal bittings (notches) which engage upon arcuately shaped ends of pins in a cylinder of the lock in order to displace drivers within a casing of the lock. When the appropriate key is inserted into the lock, the drivers are displaced to such a level as to allow rotation of the cylinder within the lock casing. The depth of penetration of the key into the cylinder is determined by the abutment of an ear upon the key shank with the exposed end of the lock cylinder.

This arrangement has the disadvantage that it is possible to rake a key or tool along the keyway in the cylinder and effect the displacement of the pins so as to allow rotation of the cylinder within the casing without using the correct key.

The raking of keys within cylinders is of particular concern in the area of master keying wherein a single key may open the entire set of locks for a building or premises.

It is an object of the present invention to provide an improved key which is adapted for use in pin tumbler locks.

It is a ftirther object of the present invention to provide a lock and key combination which provides improved anti-rake protection.

According to a first aspect of the present invention there is provided a key, suitable for use in a pin tumbler lock, including a longitudinally extending shank and a plurality of bittings in one edge surface thereof, one of said bittings, comprising a first surface, which is normal to the longitudinal extent of said shank, and a second surface, the first surface being behind said second surface in the direction of insertion of the key, in use, and the end of said shank which is inserted into said lock, in use, having a sloping leading surface to effect sliding movement of pin tumblers of the lock upon initial key insertion.

As used herein, 'normal' includes up to a few degrees of slope from 90' towards said edge surface in the direction opposite to that of key insertion, in use, i.e. a slight undercut.

Preferably the key includes a bow, from which said shank extends, and said first surface defines one side of said one of the bittings, the other side of said one of the bittings either being defined by said second surface sloping away from said edge surface, in a direction away from said bow, or being open with said second surface of said one of the bittings being parallel to said longitudinal extent of the shank.

Preferably, said second surface extends to said end of said shank.

Desirably, said first and second surfaces form a right-angled step on the shank. More desirably, said first surface defines an abutment surface which is adapted to abut a side surface of a flat-sided or substantially flat-sided pin of the lock, in use. Conveniently, said step acts, in use, as a depth stop. Advantageously said key does not have an ear upon said shank.

According to a second aspect of the present invention there is provided, in combination, a key and a lock, the key being a key according to said first aspect; and the lock having a casing and a cylinder which is rotatable relative to the casing, and which includes a key receiving slot in which ends of a plurality of pins are exposed, a side surface of one of said pins being flat or substantially flat and arranged such that at least part of said first surface of said one of the bittings and said side surface of one of said pins abut one another when the key is fully inserted into the lock, in use.

Preferably, there is a slot in the casing and the cylinder of the lock.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal schematic sectional view of a key and lock combination according to the present invention; Figure 2 is a reduced scale front view of the combination illustrated in Figure 1; and Figure 3 is a view similar to Figure 1, showing another embodiment of the invention.

Figure I shows a key 10 comprising a bow 12 and an elongate shank 14. The bow 12 comprises a circular body 16 and a neck 18 joining the circular body 16 to the elongate shank 14. The shank has a chamfered/sloping leading end surface 14a to raise pin tumblers of a pin tumbler lock as the key is inserted, in use, in the usual manner.

The shank 14 has wards (not shown) along the sides thereof and a plurality of notches or bittings 20 along at least the upper edge thereof. A terminal bitting 22 adjacent said sloping leading free-end 14a of the shank 14 is formed with a flat ledge surface 24 parallel to the longitudinal axis of the shank. An inner step surface 26 of the terminal bitting, behind the surface 24 in the direction of key insertion, extends at 90' from the ledge surface towards the upper edge of the shank. This surface 26 could alternatively be formed as a slight undercut.

As shown in the Figures, the key 10 is arranged to fit a pin tumbler lock 28 which comprises a casing 30 having a forend 3 1, and a cylinder 32 rotatably received in the casing, both the cylinder 32 and casing 30 being of circular cross-section. The casing 30 has a longitudinally extending cylindrical cavity 34 therethrough which is displaced from the central axis of the casing 30 and in which is received the cylinder. The casing 30 has an arcuate recess 36 at the forend 31 at a position around the cavity 34.

A plurality of conventional radial pin tumbler chambers 38, each having a driver 40 and a spring 42 therein, open into the cavity 34 along a common longitudinal axis, the drivers 40 being biased towards the cavity 34 by the springs 42 in the normal manner.

The cylinder 32 has an elongate slot 44 extending longitudinally therethrough and a series of radial passageways 46 extend through a wall 48 of the cylinder 32 along a common longitudinal axis to communicate with said slot 44. Each passageway has a pin 50 of circular cross-section therein. An annular flange 52 extends radially outward at a front end of the cylinder 32.

In use, the cylinder 32 is located within the casing 30 with its flange 52 abutting the inner annular surface of the recess 36, so as to limit insertion.

The pins 50 are biased into their respective slots 44 by the springs 42 and drivers 40 such that with no key in the lock, and with the chambers 38 and passageways 46 aligned, the drivers 40 enter the passageways 46 of the cylinder 32 to lie across the interface between the cylinder and the casing, thereby to prevent rotation of the cylinder relative to the casing 30.

Each pin 50 is of conventional form having a hemispherical end surface. In other words near its extremity there is a junction between its straight, cylindrical surface and its lowermost curved part. The depth of surface 26 is less than the extent of the curved part, so that as the key is inserted into slot 44 the surface 26 engages a curved part of each pin 50 in turn and thus lifts it to allow the shank to continue to full insertion. This depth condition does not of course apply when the bitting which includes the 'vertical' step surface, is the first bitting on the key, i.e. next to the bow, as will be described with Figure 3.

The insertion of the key 10 into the slot 44 in cylinder 32 thus results in the pins 50 moving vertically in response to all the bittings 20 of the key 10, including the terminal bitting 22, such that the ends of the pins 50 remote from the bittings 20 will lie at the level of the interface between the casing and the cylinder. Consequently, the respective lower surfaces of the drivers 40 will also lie at the level of that interface, thereby allowing rotation of the cylinder 32 within the casing 30 in the normal manner.

In the embodiment of Figure 1, the one of the pins furthest from the forend 3 1, and denoted by numeral 54, is wholly cylindrical, terminating at its lower end in a flat or substantially flat surface 55a, and having a wholly straight side surface 55b extending normally thereto. As described, the pins 50, in contrast, terminate at their lower ends respectively in rounded arcuate surfaces 56, which partly extend into the side surface of the pin. The depth of insertion of the key 10 into the cylinder 32 is limited by the abutment of the inner step surface 26 of the key 10 against side surface 55b of pin 54, although for clarity a slight clearance is shown in Figure 1 between the pin 54 and surface 26.

With this arrangement there is no 'lead-in' surface on the pin 54, as is the case with the other pins, i.e. their rounded/arcuate lower ends respectively. Thus this pin 54 resits any attempt successfully to 'rake' the lock, either by a wrong key or tool, since it is not possible for the key or tool to locate 'under' the pin 54 to raise it to its Figure I position.

7- It will be appreciated that the bitting 22, comprising surfaces 24 and 26, need not be at the terminal free end of the key 10, but may be at any one or more of the bittings 20, provided that the (remaining) bittings 20 are suitable to allow withdrawal of the key 10 from the lock 28. Wherever the surface 26 is provided, the flat surface 24 may also be provided, but alternatively it could be omitted, or be other than flat. Figure 3 shows an alternative embodiment where the bitting including the stop surface is adjacent the key bow, and the associated cylindrical pin is part of the first pin tumbler in the lock in the direction of key insertion. The pin is denoted by numeral 58, the vertical inner step surface by numeral 60 and the adjoining horizontal surface by numeral 62. In this example the other bitting surface 64, i.e. that at the opposite side of the bitting from surface 60, slopes away from the key upper edge surface, in the direction of key insertion, at an upwards angle.

The surface 26 or 60 is preferably normal to the longitudinal direction/axis of the shank, but it could slope up to a few degrees towards said upper edge surface of the key in the direction opposite to that of key insertion, in use, i.e. to form a slight undercut.

It will be noted that in the illustrated embodiments the key does not have the usual ear on the neck 18, i.e. adjacent the bow, to act as a stop and limit key insertion, this being unnecessary due to the stop means constituted by the pin 54 or 58 being engaged by stop surface 26 or 60 respectively. However in an alternative embodiment, such an ear could be provided, this engaging the ftont surface of the lock as the stop surface engages its associated pin. In an alternative lock form, an elongate slot/recess, aligned with slot 44, is formed in the cylinder and casing. This slot/recess is provided so that the use of a conventional key with an ear mounted upon the neck of the bow, but having otherwise suitable bittings to allow free rotation of the cylinder 32 within the casing 30, will not achieve the correct depth penetration into the cylinder 32, since with such slot/recess, such a key will be received too far into the cylinder 32, thereby preventing the operation of the lock.

The invention relates to the key alone, the combination of key and lock, the lock alone, and to a blank for said key provided with the depth stop but no other bitting or wards.

Claims

1. A key suitable for use in a pin tumbler lock, including a longitudinally extending shank and a plurality of bittings in one edge surface thereof, one of said bittings comprising a first surface, which is normal to the longitudinal extent of said shank, and a second surface, the first surface being behind said second surface in the direction of insertion of the key, in use, and the end of said shank which is inserted into said lock, in use, having a sloping leadi surface to effect sliding movement of pin tumblers of the lock upon initial key insertion.

2. A key as claimed in Claim 1, including a bow, from which said shank extends, and wherein said first surface defines one side of said one of the bittings, the other side of said one of the bittings either being defined by said second surface sloping away from said edge surface, in a direction away from said bow, or being open with said second surface of said one of the bittings being parallel to said longitudinal extent of the shank.

3. A key as claimed in Claim 1 or Claim 2, wherein said first surface is disposed towards an end of said shank.

4. A key as claimed in Claim I or Claim 2, wherein said first surface is at a terminal free end of said shank.

5. A key as claimed in any one of the preceding Claims, wherein said first and second surfaces form a right-angled step.

6. A key as claimed in Claim 5, wherein said first surface defines an abutment surface which is adapted to abut a flat-sided or substantially flatsided pin of the lock, in use.

7. A key as claimed in either Claim 5 or Claim 6, wherein said step acts, in use, as a depth stop.

8. A key as claimed in Claim 1, including a bow including a neck joining the bow to the shank, which neck is not provided with an ear as with a conventional key.

9. A key as claimed in Claim 2, wherein said bow includes a neck joining the bow to the shank, which neck is not provided with an ear as with a conventional key.

10. In combination, a lock, and a key as claimed in any one of Claims 1 to 9, the lock having a casing and a cylinder which is rotatable relative to the casing, and which includes a key receiving slot in which ends of a plurality of pins are exposed, a side surface of one of said pins being flat or substantially flat and arranged such that at least part of said first surface of said one of the bittings and at least part of said side surface of said one of the pins abut one another when the key is fully inserted into the lock, in use.

11. A combination as hereinbefore described, with reference to, and as shown in, the accompanying drawings.

11. A combination as claimed in Claim 10, wherein when said one of the bittings is other than the last bitting to be received in the lock, in use, upon full key insertion, the depth of said first surface is less than a curved lower I surface part of each of the pins which said bitting must pass as the key is fully inserted.

12. A combination as claimed in Clairn 10 or Claim 11, wherein there is a slot in the casing and the cylinder of the lock aligned with and continuing said key receiving slot.

13. In combination, a pin tumbler lock and a key for use in said lock, the key including a longitudinally extending shank and a plurality of bittings in one edge surface thereof, one of said bittings comprising a first surface which is normal to the longitudinal extent of said shank, and the lock having a casing and a cylinder which is rotatable relative to the casing, and which includes a key receiving slot in which ends of a plurality of pins are exposed, a side surface of one of said pins being flat or substantially flat and arranged such that at least part of said first surface of said one of the bittings and at least part of said side surface of said one of the pins abut one another when the key is fully inserted into the lock, in use.

14. A key as hereinbefore described, with reference to, and as shown in, the accompanying drawings.

15. A combination as hereinbefore described, with reference to, and as shown in, the accompanying drawings.

- I Z_ - Amendments to the claims have been filed as follows CLAIMS 1. A key suitable for use in a pin tumbler lock, including a longitudinally extending shank and a plurality of bittings in one edge surface thereof, the end of said shank which is inserted into said lock, in use, having a slopi leading surface to effect sliding movement of pin tumblers of the lock upon initial key insertion, the bitting nearest said end of the shank comprising a first surface, which is normal to the longitudinal extent of said shank, and a second surface parallel or substantially parallel to said longitudinal extent of the shank so as to define a right-angled or substantially right-angled step with said first surface, the first surface being behind said second surface in the direction of insertion of the key, in use, and the first and second surfaces of the bitting extending across the whole width of said shank.

2. A key as claimed in Claim 1, wherein said second surface extends to said sloping leading surface.

3. A key as claimed in Claim 1 or Claim 2, wherein said first surface defines an abutment surface which is adapted to abut a flat-sided or substantially flat-sided pin of the lock, in use.

4. A key as claimed in any one of Claims I to 3, wherein said step acts, in use, as a depth stop.

5. A key as claimed in any one of Claims 1 to 4, including a bow having a neck joining the bow to the shank, which neck is not provided with an ear as with a conventional key.

6. In combination, a lock, and a key as claimed in any one of Claims 1 to 5, the lock having a casing and a cylinder which is rotatable relative to the casing, and which includes a key receiving slot which ends of a plurality of pins are exposed, a side surface of one of said pins being flat or substantially flat and arranged such that at least part of said first surface of said bitting and at least part of said side surface of said one of the pins abut one another when the key is fully inserted into the lock, in use.

7. A combination as claimed in Claim 6, wherein the depth of said first surface is less than a curved lower surface part of each of the pins which said bitting must pass as the key is fully inserted, in use.

8. A combination as claimed in Claim 6 or Claim 7, wherein there is a slot in the casing and the cylinder of the lock aligned with and continuing said key receiving slot.

9. In combination, a pin tumbler lock and a key for use in said lock, the key including a longitudinally extending shank and a plurality of bittings in one edge surface thereof, the bitting which is the first bitting to be received in the lock, in use, upon full key insertion, comprising a first surface which is normal to the longitudinal extent of said shank, and the lock having a casing and a cylinder which is rotatable relative to the casing, and which includes a key receiving slot in which ends of a plurality of pins are exposed, a side surface of one of said pins being flat or substantially flat and arranged such that at least part of said first surface of said bitting and at least part of said side surface of said one of the pins abut one another when the key is fully inserted into the lock, in use.

10. A key as hereinbefore described, with reference to, and as shown in, the accompanying drawings.