GB2358670A - Key and cylinder lock - Google Patents

Abstract

A pin tumbler cylinder lock of conventional form is modified by the provision of grooves (24,25;41,42,43) in its outer surface and a burr strip (17;17a) disposed to close the opening of the key receiving slot at the periphery of the plug (11) of the cylinder lock. The strip has a spring section (20) at its one end and upstanding wards (18,19;35,36,37) at its longitudinal side(s), and is slidably disposed in the lock so that it is moved to compress its spring section (20) when a key (10) of the lock is inserted into the key receiving slot. The key (10) moves the strip to a position where its wards are aligned with the grooves respectively, the wards then also being aligned with corresponding respective notches (32,33;38,39,40) in the longitudinal edge surface (31) of the key opposite that containing the usual bitting (29). The key has on said surface (31) an abutment surface (34) behind the notches, to engage and move the strip. The provision of the warding and the need to move the strip accurately longitudinally provides extra security.

Description

2358670 - I - CYLINDER LOCKS This invention relates generally to cylinder

locks and particularly to a pin tumbler cylinder lock, and also to a key therefor.

An object of the invention is to provide a key for use with a cylinder lock incorporating improved security features.

According to the present invention there is provided a flat key for a cylinder lock, the key comprising a bow and a shank, one longitudinal edge surface of the shank having bitting and the opposite longitudinal edge surface of the shank having at least one notch to allow the key to move past a ward or respective wards in or of a casing of the lock when, in use, the key is inserted in a plug of the lock and the plug rotated in said casing, there being an abutment surface at said opposite longitudinal edge surface at a longitudinal position, in the key insertion direction, in use, behind said notch or the one of said notches nearest said bow.

In use, upon insertion of said key, said abutment surface drives a lock casing component forward in the direction of key insertion so that said ward or wards, which are provided by or on said component are moved from a first position, in which they block rotation of the plug in said lock casing, to a second position in which such rotation is allowed.

Preferably the component is a burr strip which 'closes' a longitudinal entry slot in one side of the plug diametrically opposite drillings for the pins of a pin tumbler lock plug, and conveniently the or each ward is formed by turning up material from the or each side edge of the strip.

Desirably the strip has an integral spring formation at one end, which forces the strip to its first position in the lock when said key is not received in the lock.

The invention will now be described, by way of example, in which:

Figure 1 is a schematic, exploded perspective view of a key of the invention, together with a plug and a security component of a pin tumbler lock with which the key is intended to use, Figure 2 is an 'assembled' view of the lock components shown in Figure 1 with the security component in a locking position, Figure 3 is a side view like Figure 2, but with.the key inserted into the plug and the security component moved by the key to an unlocking position.

Figure 4 is a perspective view corresponding to Figure 3, Figure 5 is a view corresponding to 1, for another embodiment of the invention, and Figure 6 is a perspective view of the Figure 5 embodiment with the key inserted in the plug.

Figure 1 shows a first embodiment of a flat-key 10 for use in a pin tumbler cylinder lock comprising a rotatable cylindrical plug 11 in a lock casing, a part of which is shown in phantom at 12. The casing contains, in a conventional form, a series of circular-section drillings 13 communicating with the conventional-circular-section opening through the casing for reception of the plug 11. In the conventional manner. the drillings 13 contain spring-loaded drivers which act on the lock pins which are received in the central key slot of the plug when there is no key inserted into said slot. In the normal manner the drivers extend across the interface between the plug and lock casing, m this state so as to prevent rotation of the plug relative to the lock casing. Figure 1 also shows a circlip 14 or the like in an annular groove at the inner end of the plug to retain a connecting bar 15 which, in use, acts upon a locking mechanism to operate a bolt or latch of the lock assembly.

Whilst there are various manufacturing methods known to produce the driRings l j, one method, which is used to produce the lock casing 12 shown in Figure 1, is to drill through the wall of the lock casing at the lower side thereof, as viewed in Figure 1, namely at the side of the casing remote from its extension part which contains the spring-loaded drivers in use. Accordingly said drillings extend through said wall, the drilling then effectively passing through the circular-section plug reception opening in the casing and into. the extended upper side of the lock casing, as viewed in Figure 1 to provide, for example, the six closed ended drillings 13 illustrated. With this arrangement it will be appreciated that there are six corresponding short drillings 16 in the lower wall of the casing which, in use, will be angularly aligned with the open slot in the bottom of the plug when said plug is in its locked position without any key inserted and thus unable to rotate relative to the lock easing. In use means thus must be provided to prevent the pins in the plug dropping into said lower short drinings in the lock easing. Such means is provided in the form of a burr strip 17 which fits in a longitudinal groove in the lock casing at a position over the short drillings 16, the strip 17 lying just below the outer peripheral surface of the plug so that the pins are effectively retained in said plug prior to key insertion.

As will be described, the strip 17 is adapted to provide two security features in conjunction with the specially adapted flat-key 10 of the invention.

Firstly, as shown in Figures 1 to 4, the strip, which can be of metal or plastics, and which is of generally rectangular form along most of its length, has two pairs of cuts in one, of its longitudinal sides, with the material between each pair of cuts being bent up at 901 out of the plane of the strip to provide upstanding projections in the form of wards, 18, 19 respectively. In the embodiment shown in Figure 1, the ward 18 is generally square whilst the ward 19 is generally triangular, but with a short flat top surface.

At the'end of the strip which is innermost in the lock casing, in use, the rectangular form is cut away by a series of V-notches in alternate sides of the strip to form a zig-zag spring-section 20. The strip is arranged in the groove in the'lock casing so that in the non-operative state of the lock, the springsection 20 is extended so as to position the end of the strip remote from the section 20 at an inner side 21 of an annular groove 22 next to a cylindrical flange 23 defining the front face of the plug..

-5.

The outer peripheral surface of the plug is formed with two axially spaced annular grooves 24, 25 respectively approximately half-way along the length of the plug', with the doss-sec"tional shape of said-grooves. co ffes. poiiding-to' the cross-sectional shapes of the wards 18, 19 respectively.

In the assembled lock, the strip 17 and plug assume the relative relationship shown in Figure 2 when there is no key inserted into the lock. With this arrangement the wards 18, 19 project slightly into the slot in the lower surface of the plug, at one side of the centre of the key slot. As can be seen from Figure 2, the wards 18, 19 are, in this position, out of alignment longitudinally with the grooves 24, 25. Accordingly even if a key were to be inserted with the correct bitting to raise the pins and thus ordinarily allow rotation of the plug in the lock casing, this arrangement would prevent such rotation, with the strip remaining in its Figure 2 position relative to the plug, in that the wards 18,19 would block such rotation by engagement thereagainst of the side of the slot in the lower surface of the plug.

However, if the correctly bitted key were also drivingly to slide the strip forwardly, in the direction of key insertion, this would bring the wards 18, 19, into longitudinal alignment with the grooves 24, 25 respectively, thereby allowing relative rotation between the plug and the strip, and thus the plug and the lock casing. By providing the springsection 20, this objective is accomplished, in that the strip is automatically biased by the spring-section 20, when there is no key in the lock, to provide the security locking function by way of the wards, whereas when the correct key is fully inserted the strip is moved against its spring-section bias to cause alignment of the wards with -the grooves in the outer periphery of the plug to allow rotation of the plug - So as correctly to co-operate with the strip 17, the key 10 is in the form of a spec. ially - modified co'n'ventional flat-key. - As'canhe best'seen'from-'Fig-ure'l -the key has a conventional bow 26 and shank 27. In its one longitudinal edge surface 28, which is shown uppermost in Figure 1, there is the usual bitting 29 so as correctly to raise the pins, in use, in the plug, so as to provide a clear interface between the upper peripheral surfaces of the plugs and the respective lower surfaces of the drivers, so as to allow plug rotation in the normal manner upon turning the key. Along said edge surface 28,.immediately adjacent to the bow is a conventional ear 30 for abutting the front face of the plug to denote correct full insertion of the key into the plug, in use. 'So far the key described is entirely conventional.

However in its other, lower, edge surface 3 1, as viewed in FigureI, there is provided a first notch 32, matching the cross-sectional shape of ward 18, and a second notch 33, spaced longitudinally along the edge surface 29 from the notch 32, matching the cross-sectional shape of die ward 19. Thus when the key is fully inserted in the plug, and, as will be described, the wards 18, 19 are longitudinally aligned with the grooves 24, 25, the wards will also be longitudinally aligned with the notches 32, 33, so that as the key is turned and the plug rotates, the wards 18, 19 do not act as stops as the notches 32, 33 move over and past them. As shown in Figure 1, the lower edge surface 3 1 of the key is stepped to define a short first portion 3 1 a which joins the bow 26, and a much longer second portion 31b, which extends to the free end of said surface 3 1, with the notches 32 and 33 being in the second portion 3 lb. The first and second portions are parallel and are joined at the step by a short surface 34 which is normal to the first and second portions, and disposed longitudinally forwardly of the ear in the key insertion direction. This surface 34 acts, in use, as an abutment surface to engage the end of the strip 17 remote from the spring-section 20.

Figure 2 shows the disposition of the strip 17 in the lock casing relative to the plug 11 when the lock is in its non-operative state, i. c. without a key inserted. It can be seen that in this state, the spring- section 20 is in its normal, extended form, with the axial position of the strip relative to the plug being such that the strip extends across the groove 22, with. the short flat end of the strip remote from the section 20 being alignedwith the inner side of the flange 23. In this position of the strip, the wards 18, 19 respectively lie out of alignment with the respective grooves 24, 25, each ward lying, as viewed in Figure 2, to the left of its associated groove in the longitudinal direction of the plug.

In use, if the correct key 10 is inserted into the lock, the bittings, 29 will, in the conventional manner, raise the pins to the correct respective levels for producing the clear interface between the outer peripheral surfaces of the plugs and the drivers contained in the lock casing. Moreover as the key is inserted in the key slot in the plug, the abutment surface 34 will reach the leading flat end surface of the strip before the ear 30 reaches the front face of the plug. As a result continued insertion of the key will, by way of the abutment surface 34, force the strip 'inwardly' with its spring-section 20 being compressed, the geometry of the key being such that upon full insertion, defined by engagement of the ear 30 against the front face of the plug, the key will have moved the strip to the position shown in Figures 3 and 4 where the wards 18, 19 are respectively aligned longitudinally with the grooves 24, 25, the notches 32, 33 in the key, also, in this position, being longitudinally aligned with the grooves 2 4, 25 respectively, and also with the wards 18, 19. Accordingly rotation of the key will result in corresponding rotation of the plug in the lock casing as during such rotation the key moves past the wards, by virtue of the notches 32 and 33 respectively, and the plug moves around said wards by virtue of these being received in the grooves 24, 25 respectively.

If an attempt is made to operate the lock with a key which does not have the correct bitting, then, in the usual manner, the plug cannot be turned. Similarly, a key which does not have the correct form. and position of notches 32, 33, would also not be able to rotate the plug, in that such misaligned notches would not be able to move past the wards 18, 19 which would act as blocking members against a side of the key. Moreover even a key having the correct bitting and the correct form and disposition of notches would not be able to operate the plug if the key did not have the surface 34 which moves the strip inwardly in the lock casing, since if the strip is not moved the wards are not only non-aligned with the notches 32, 33, but are also misaligned with the grooves 24, 25, so that any attempt at rotation of the plug would result in the wards engaging against a side of the plug, or a side of the key slot defined in the plug. Accordingly not only is there the security provided by the need for a correct key to have the correctly-shaped notches in the correct position, but there is the added security that a correct key must also have a correctly positioned abutment surface in order to move and accurately position the strip so that the wards are also aligned with the grooves in the external surface of the plug.

A further embodiment is shown in Figures 5 and 6, this differing from the embodiment shown in Figures 1 to 4 solely by virtue of there now being provided three wards 35, 36, 37 respectively on the strip, here denoted as 17a, with the key 10a having three corresponding notches 38, 39, 40 respectively and the exterior surface of the plug 11 a having three corresponding grooves 41, 42, 43 respectively. It will be noted that the ward 35 is at the opposite longitudinal side of the strip from the wards 36, 37. In this example the ward 35 is the same shape and size as the ward 36, but this need not be so, and it will be appreciated that the wards can take any suitable size or form and that any number thereof can be the same as or different from each other. Clearly the greater number/variety of wards provided increases the security.

As well as relating to a key, the invention also relates to a blank for. such a key, this being a blank which is provided with the step but without the bitting or notches.

Although the key illustrated with both embodiments has a conventional ear, this is not essential and has no affect on the invention. In one alternative form of key without an ear, there is full and correct insertion of the key when the abutment surface 34 fully compresses section 20 of the burr strip, at which position of the key the wards on the strip are aligned with the notches in the key and the grooves in the cylinder, to allow turning of the plug. In an alternative form of key without an ear, the key is of the type as disclosed in our co-pending UK Patent Application No. 0024473. 1, and the lock incorporates a flat-sided pin tambler which acts as the stop for key insertion in place of an ear on the key.

CLABIS 1. A flat key for a cylinder lock, the key comprising a. bow and a shank, one longitudinal edge surface of the shank having bitting and the opposite longitudinal edge surface of the shank having at least one notch to allow the key to move past a ward or respective wards in or of a casing of the lock when, in use, the key is inserted in a plug of the lock and the plug rotated in said casing, there being an abutment surface at said opposite longitudinal edge surface at a longitudinal position, in the key insertion direction, in use, behind said notch or the one of said notches nearest said bow.

Claims (1)

1. 2. A key as claimed in Claim 1, wherein the abutment surface is formed as

   a step between first and second portions of said opposite longitudinal edge surface of the shank.

   3. A key as claimed in Claim 2, wherein said first portion is a flat surface extending from said bow to said step.

   4. A key as claimed in Claim 3, wherein said first portion is parallel to said second portion.

   5. A key as claimed in any one of Claims 2 to 4, wherein the first portion is shorter than the second portion.

   6. A key as claimed in any one of Claims 2 to 5, wherein the step is normal to the longitudinal extent of the shank.

   7. A blank for a key as claimed in any one of the preceding claims.

   8. A cylinder lock comprising a casing, a plug rotatable in the casing, the plug having a key receiving slot therein, which slot is open at the periphery of the plug, a multiplicity of spring loaded tumblers movable, on reception of a key in use, into said slot, from respective positions where the interface between the plug and the casing is obstructed, thereby preventing rotation of the plug, to respective positions where said interface is unobstructed, and a ward movable, on saidreception of the key, in use, to a position where itis in alignment with a groove in the periphery of the plug and a notch of the key, to allow rotation of the plug.

   9. A lock as claimed in Claim 8, wherein the ward is provided on a strip disposed to close said key receiving slot at the periphery of the plug.

   10. A lock as claimed in Claim 9, wherein said insertion of the key, in use, moves the strip from a first position to a second position, the strip being sprung to return to said first position upon key removal from the plug.

   11. In combination a key as claimed in any one of Claims 1 to 6 and a lock as claimed in any one of Claims 8 to 10.

   12. A flat key for a cylinder lock substantially as hereinbefore described, with reference to, and as shown in the accompanying drawings.

   13. A cylinder lock substantially as hereinbefore described, with reference to, and as shown in the accompanying drawings.