CYLINDER LOCK AND KEY SYSTEM

Abstract

 A cylinder lock and key system including, cylinder locks and keys. The locks are of the kind comprising a housing having a cylindrical bore; and a cylindrical plug (200, 400) which is rotatably journaled in the housing about a rotational axis and which exhibits a front end and a keyway (206), which extends axially from an entrance opening at the front end. The keys (100, 300) are of the kind comprising a key bow (102,); and a key blade (104, 304) extending forwardly from the key bow to a key tip, which key blade is insertable in a forward longitudinal direction to a fully inserted position in the keyway of corresponding locks and rotatable about the rotational axis when inserted. The plugs and keys are provided with cooperating stop surfaces for defining the fully inserted position of the keys in the keyways. The cooperating stop surfaces comprise at least two first stop surfaces (120a, 120b) arranged at the key blade (104) of each key, each first stop surface facing forward in the insertion direction and being positioned at a selected one of a predetermined number of selectable axial positions, and at least two second stop surfaces (220a, 220b) arranged in the keyway (206) of each plug, each second stop surface being positioned at a selected one of the predetermined number of selectable axial positions. The first and second stop surfaces are arranged such that at least one first stop surface is in contact with a corresponding second stop surfaces when a correct key is fully inserted in the keyway of a corresponding lock. At least two first stop surfaces (120a, 120b) are defined by a bottom surface of a respective bore (122a, 122b) which extends longitudinally into the key blade (104) from a key tip portion (105) and at least two second stop surfaces (220a, 220b) are defined by an end surface of a respective stop member (222a, 222b) which extends longitudinally into the keyway (206) from a rear portion of the plug (200).

Description

Background

[0001] The invention concerns a cylinder lock and key system comprising a plurality of cylinder locks and a plurality of keys, each key being arranged for operating at least one of the cylinder locks. Particularly, the invention concerns a master key system wherein at least one key is arranged to operate several of the locks comprised in the system. The invention also concerns a cylinder lock and key combination for such a system as well as a key and a key blank for producing a key for such a system.

[0002] Cylinder locks comprise a housing or stator with a cylindrical axial bore housing a cylindrical rotatable plug, core or rotor. The plug exhibits an axial keyway for insertion of a key provided with a code. The plug is further provided with code sensing members which detect the code of the inserted key and which allows rotation of the plug in the housing only when a key having a correct code, which corresponds to the lock in question, is fully inserted into the keyway.

[0003] There exist several general types of cylinder locks, such as pin tumbler locks and disc tumbler locks. The pin tumbler locks comprise radially displaceable pin tumblers which are arranged in the plug and housing, to sense or detect a code arranged at an edge and/or a side of the key blade. Keys where the code is formed as axially spaced code surfaces arranged at different heights or radial positions along the edge of the key blade normally exhibits a saw teeth like shape and are sometimes referred to as cut keys or conventional notched keys. Another type of keys is the so called dimpled keys, where the code is formed of a number of normally conical recesses formed in the sides and/or edges of the key blade. These and other general types of cylinder locks and corresponding keys are well known in the art and are not further described here.

[0004] In order for the code sensing members to be able to correctly detect the code of the key, the key needs to be inserted to a well defined position in the keyway when detection is made. This position is normally referred to as the fully inserted position of the key in the keyway. Traditionally, the fully inserted position is defined by a collar or shoulder arranged at the key, at the junction between the key blade and the key bow. The shoulder exhibits a stop surface which is facing the front end of the plug and the front end of the plug exhibits a corresponding stop surface. Alternatively the fully inserted position may be defined by a stop surface arranged at the tip of the key, which surface makes contact with a stop member arranged at a rear portion of the keyway For operating the lock from its locked to its unlocked mode, the key is inserted until the two stop surfaces make mutual contact and prevent further insertion of the key. The key has then reached the fully inserted position, at which the code sensing members of the plug are radially aligned with the respective intended code surfaces of the key. If the key is a correct key, i.e. a key having the correct code for the lock in question, the code surfaces of the key, at this key position, are arranged such that the code sensing members will release the plug from the housing. Thereby the plug may be rotated relative to the housing, e.g. by means of the key bow, for manoeuvring the lock to its unlocked mode.

[0005] Lock and key systems referred to as master key systems are systems comprising a plurality of locks and keys which are arranged in a hierarchic order. For example, some keys may be configured to operate only one respective lock, whereas other keys may be configured to operate several different locks and one or several yet other keys, so called grand master keys, may be configured to operate all locks in the system. Correspondingly, some locks may be configured to be operated by only one key at each hierarchic level, whereas other locks may be configured to be operated by several keys at each hierarchic level. Such master key systems find great use e.g. in office buildings, hospitals, within companies and the like, where it is desirable to control the access to certain doors for each key holder. However, less complicated master key systems are also frequently used at e.g. apartment blocks where e.g. tenants should have access to only one or a few doors, whereas landlords and service personnel should have access to several and in some instances all doors in the building.

[0006] Especially at comparatively complicated master key systems involving great numbers of locks and keys as well as many hierarchic levels and sophisticated access combinations it is of great importance that the possible number of permutations for the correct lock and key code combinations are high. One way of increasing the number of possible permutations in a system is to increase the number of pin or disc tumblers in the plugs and the corresponding number of axial code surface positions at the keys. Another way is to increase the number of selectable code heights at each axial code surface position at the keys, i.e. to decrease the pitch between the possible code heights for each pin or disc tumbler. Yet another way to increase the number of permutations in a system is to vary the profiles, i.e. the cross sectional shapes of the keyway and the key blades. However, these ways of increasing the number of possible permutations of a system are limited and, in practice, suffer from some disadvantages. It would therefor be advantageous to find another simple, reliable and readily applicable way to increase the number of possible permutations in master key systems.

Prior art

[0007] EP 0 637 663 B1 discloses a key and lock combination wherein the key is provided with a first stop surfaces for defining the fully inserted position when inserting the key into the lock and a further stop surface for defining the fully inserted position when the key is inserted into a key copying machine. By separating the two stop surfaces axially from each other it is achieved that unauthorized persons can not produce a true copy of an original key by means of fully inserting a key blank into a regular key copying machine.

[0008] EP 1 523 603 B1 discloses a lock and key combination wherein a reversible key is provided with two shoulders arranged at a respective edge of the key blade. Each shoulder exhibits a forwardly facing stop surface and is provided with a recess forming a laterally facing additional control surface. The lock comprises a plug provided with a keyway and a recess formed in the front end of the plug. The recess defines a forwardly facing stop surface interacting with one of the stop surfaces of the key and a laterally facing additional control surface interacting with a corresponding one of the lateral control surface of the key. By this means, it is possible to increase possible variations of the cross sectional profiles of the corresponding keyways and key blades.

[0009] US 2,065,294 discloses a lock and key combination wherein a non-reversible key is provided with two stop surfaces arranged at opposite edges of the key blade. One of the stop surfaces is arranged at the coded edge of the key blade and the other stop surface is arranged at the spine edge of the key blade. The core is provided with two corresponding stop surfaces each cooperating with a respective one of the key's stop surfaces. By utilizing two pairs of stop surfaces the number of permutations may be increased.

[0010] EP 1 048 804 A1 discloses a locking system comprising a key and a lock cylinder with a keyway. The lock and the key are provided with stop elements for defining the maximum insertion depth of the key. The stop elements are arranged such that they are positioned in the keyway spaced apart from the key tip and from the ends of the cylinder when the key is fully inserted in the keyway. The key further comprises a reference element for defining a correct position of the key during the milling process for producing the key from a key blank. The reference element is arranged to lie outside of the key way and spaced apart from the ends of the cylinder when the key is fully inserted in the keyway.

[0011] WO 96/03562 discloses a cylinder lock and key combination wherein the plug of the cylinder lock comprises an elongate element which extends axially in the key slot or key way. The key is provided with a corresponding hole which extends longitudinally from a front tip of the key blade and which receives the elongate element when the key is inserted into the keyway. The elongate element makes it difficult to pick the lock by using a lock-picking tool inserted into the keyway.

Summary of the invention

[0012] It is an object of the present invention to provide an enhanced cylinder lock and key system.

[0013] Another object is to provide such a system which exhibits a high degree of security and which renders it difficult to wrongfully produce unauthorized keys.

[0014] A further object is to provide such a system at which a comparatively high number of possible permutations may readily be achieved.

[0015] Yet another object is to provide such a system which is reliable in use.

[0016] A still further object is to provide such a system at which the cylinder locks may be of the modern type having plugs in which the keyway extends radially in one direction all the way to the periphery of the plug, thereby forming a keyway which is open in one radial direction.

[0017] These and other objects are achieved by a cylinder lock and key system as defined in the preamble of claim 1 and which exhibits the special technical features defined in the characterizing portion of that claim.

[0018] A cylinder lock and key system includes cylinder locks and keys. The cylinders are locks of the kind comprising a housing having a cylindrical bore; and a cylindrical plug which is rotatably journaled in the housing about a rotational axis and which exhibits a front end and a keyway, which extends axially from an entrance opening at the front end. The keys are of the kind comprising a key bow; and a key blade extending forwardly from the key bow to a key tip, which key blade is insertable in a forward longitudinal direction to a fully inserted position in the keyway of corresponding locks and rotatable about the rotational axis when inserted. The plugs and keys are provided with cooperating stop surfaces for defining the fully inserted position of the keys in the keyways. The cooperating stop surfaces comprise at least two first stop surfaces arranged at the key blade of each key, each first stop surface facing forward in the insertion direction and being positioned at a selected one of a predetermined number of selectable axial positions, and at least two second stop surfaces arranged in the keyway of each plug, each second stop surface being positioned at a selected one of the predetermined number of selectable axial positions. The first and second stop surfaces are arranged such that at least one first stop surface is in contact with a corresponding second stop surfaces when a correct key is fully inserted in the keyway of a corresponding lock. At least two first stop surfaces are defined by a bottom surface of a respective bore which extends longitudinally into the key blade from a key tip portion and at least two second stop surfaces are defined by an end surface of a respective stop member which extends longitudinally into the keyway from a rear portion of the plug.

[0019] By arranging at least two forwardly facing first stop surfaces at axially selectable positions at the key blade and a corresponding number of oppositely facing second stop surfaces at a corresponding number of selectable positions in the keyway, it is possible to require that any key and lock combination exhibits a correct configuration of the first and second stop surfaces for allowing the key to be inserted into the fully inserted position. By this means it is possible to define a number of possible permutations for the system merely by arranging the stop surfaces at different axial positions.

[0020] It is for example possible to provide the keys with two first stop surfaces which each may be positioned at any one of three different selectable axial positions and the plugs with two corresponding second stop surface which also may be positioned at any one of three corresponding selectable positions.

[0021] Hereby it is possible to achieve 3² = 9 possible combinations merely by means of the cooperating stop surfaces. The system may also be given permutations in a traditional manner by the arrangement of the tumblers and the code surfaces on the keys as well as by variation of the keyway and key blade profiles. At this example, the total number of possible system permutations equals the number of traditionally accomplished permutations multiplied by 9. The cooperating first and second stop surfaces thus provides for that the total number of system permutations may be manifold increased in a simple and yet reliable manner. By varying the stop surface combinations it is also possible distinguish different groups of lock and key combinations e.g. within a master key system. For example the stop surface combinations may be used to differentiate lock and key combinations that are intended for different countries, different retailers or different customers and the like.

[0022] The arrangement of the first stop surfaces being defined by a respective bottom surface of a longitudinal bore results in that the first stop surfaces are concealed within the key blade. Hereby it is difficult for unauthorized persons to reveal the correct axial position for the first stop surfaces and thereby to produce unauthorized copies of the key. The first stop surface arrangement further allows for that the keys and key blanks comprising the first stop surfaces may readily be produced by traditional cutting operations complemented by two drilling operations. A further advantage of arranging the first stop surfaces in internal longitudinal bores in the keyway is that such an arrangement does not change the external surfaces of the key blade such that these surfaces may be utilized for arranging e.g. profile ribs, profile groves and side codes.

[0023] The arrangement of the second stop surfaces being defined by an end surface of a respective stop member which extends longitudinally in the keyway, allows for a comparatively easy way to fix the second stop surfaces at the desired positions in the key way. The fact that the second stop surfaces are arranged inside the keyway also renders it difficult to observe or detect the positions of the second stop surfaces. This in turn makes it more difficult for unauthorized persons to produce keys which may be used for operating the lock in question.

[0024] At least one of said bottom surfaces may be arranged within the longitudinal projection of another of said bottom surfaces.

[0025] At least two of said bores may be co-axial.

[0026] The at least one of said bores may be cylindrical.

[0027] At least one of said stop members may be arranged as a longitudinal extension of another of said stop members.

[0028] At least two of said stop members may be co-axial.

[0029] At least one of said stop members may be cylindrical.

[0030] At least two of said stop members may be arranged on an exchangeable component which is removably fixed to the plug.

[0031] The keys may be provided with a number of code surfaces arranged one after the other in the longitudinal direction of the key blade; and the plugs may be provided with radially displaceable pin tumblers, each code surface being arranged to cooperate with a corresponding pin tumbler when the key blade is fully inserted in the keyway, and at least one first stop surface may be positioned longitudinally rearward of the front most code surface.

[0032] The key tip may exhibit a forwardly facing front edge and at least one of said bores may debouch at the front edge.

[0033] At least one key may be a reversible key, the key blade of which exhibits at least two primary first stop surfaces and at least two secondary first stop surfaces wherein the primary and secondary first stop surfaces are arranged symmetrically with regard to a longitudinal centre axis of the key blade.

[0034] The keys may be provided with a code arranged at the key blade for cooperating with corresponding pin tumblers of the plugs, which code exhibits a code cut angle α and code surfaces which are radially separated by an integer multiple of a code surface pitch, p, and wherein the selectable axial positions for the first and second stop surfaces are axially separated by a stop separation distance q, wherein q ≥ 0,5 * p * tan α.

[0035] The first stop surfaces may be positioned closer to a key blade edge which is arranged opposite to an edge (comprising a code, than to the edge comprising the code.

[0036] The first stop surfaces may be positioned centrally between two mutually opposite key blade sides and at essentially the same distance from said key blade sides as from an edge being arranged opposite to to an edge comprising a code.

[0037] The invention also relates to a cylinder lock and key combination, a key for a cylinder loch and key system, a key blank for producing such a key and a cylinder lock for a cylinder lock and key system which exhibits the same objects and advantages as the system. The cylinder lock and key combination, the key, the key blank and the cylinder lock exhibit objectives, features and advantages corresponding to those of the system.

[0038] The first and second stop surfaces may thus be applied to cylinder lock and key combinations comprising merely one cylinder lock and one or a few keys. At such cases, the concealed arrangement of the second stop surfaces will make unauthorized key production difficult. Additionally, the possible first and second stop surface combinations may be used for differentiating several lock and key combinations one from the others. Correspondingly, when the first stop surfaces are applied to keys and key blanks, unauthorized key production and key copying is prevented or made difficult.

[0039] Further objects and advantages of the invention appear from the description of embodiments below and from the appended claims.

[0040] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. If not specified differently, a radial direction of a key is to be understood as a direction which is radial to the axis of rotation when the key is inserted in a plug and rotated therewith.

Brief description of the drawings

[0041] In the following detailed descriptions of exemplifying embodiments will be given with reference to the figures, in which:

Fig. 1a is a perspective view of a key comprised in a cylinder lock and key system according to one embodiment of the invention and fig. 1b shows a detail thereof in enlarged scale.

Fig. 2 is a perspective view of a plug for a cylinder lock comprised in the cylinder lock and key system comprising the key shown in fig 1a.

Fig. 3a is a side view of the key shown in fig 1a, fig 3b is a front view thereof and fig. 3c is an opposite side view. Fig. 3d shows a detail of the front view in enlarged scale and fig. 3e shows a detail of the side view shown in fig 3c, in enlarged scale.

Fig. 4a is a longitudinal section of the plug shown in fig. 2 with the key shown in figs 1a inserted. Fig. 4b shows a detail thereof in enlarged scale and fig. 4c is a rear view thereof.

Fig. 5a is a longitudinal section showing a detail of a key inserted into a plug and fig. 5b is a corresponding section showing the same key inserted into another plug.

Detailed description of embodiments

[0042] Figs. 1a-b and 3a-d illustrate a key 100 comprised in a cylinder lock and key system according to an embodiment of the invention. The key 100 comprises a key bow 102 and a key blade 104 which protrudes in a forward longitudinal direction from the key bow 102 to a key tip portion 105 of the key blade 104. The key tip portion 105 constitutes a front most portion of the key blade 104. The key blade 104 exhibits a profiled cross section as seen in fig. 1a. The key blade 104 further exhibits a first key blade side 106 and a second key blade side 108 which is arranged in parallel with and opposite to the first key blade side 106. The key blade sides 106, 108 are joined by a lower key blade edge 110 and an upper key blade edge 112. The upper key blade edge 112 is provided with a code 114 which has been cut into the upper edge 112. The key 100 is thus a so called sawn or cut key. The key is further insertable into the plug 200 shown in figs. 2 and 4a-c.

[0043] The key blade 104 exhibits a height direction which is parallel with the key blade sides 106, 108 and perpendicular to the longitudinal direction of the key blade 104. The height increases in the direction from the lower key blade edge 110 towards the upper key blade edge 112.

[0044] The code 114 comprises several code surfaces 116', 116" arranged one after the other at positions which are fixed in the longitudinal direction. As best seen in fig. 3d, the code surface 116' is arranged at a front most code position whereas the other code surfaces 116" are arranged at code positions being further spaced apart from the key tip portion 105. At this example the key tip 105 is pointed and comprises a front most apex 105a.

[0045] Each code surface 116', 116" is arranged to be aligned with and come in contact with a respective tumbler pin (not shown) when the key 100 is inserted in the plug of a cylinder lock for which the key is intended. The code surfaces 116', 116" are arranged at different possible code surface depths which may be measured as the code surface distance from the lower edge 110 of the key blade 104. The possible code surface depths are separated in the height direction by a code pitch which is the smallest distance in the height direction by which the code surfaces may be separated.

[0046] The key 100 is provided with three first stop surfaces 120a, 120b, 120c. The first stop surfaces 120a-c are arranged for defining a fully inserted position when the key blade 104 is inserted into the plug 200. In the example shown, two 120a, 120b, of the first key stop surfaces are defined by a bottom surface of a respective bore 122a, 122b. The bores 122a, 122b extend longitudinally from a forwardly facing front edge surface 123 arranged at the key tip portion 105. The front edge surface 123 has been formed by arranging a cut out in the key tip portion 105. A portion of the front edge surface 123 which is arranged in proximity to the mouth of the bore 122b further constitutes a third first stop surface 122c.

[0047] In the shown example one of the bores 122a is arranged as a coaxial rearward extension with reduced diameter of the bore 122b. The bottom surface of the rearmost bore 122a and thereby the corresponding first stop surface 120a is thus arranged centred within the longitudinal projection of the bottom surface of bore 122b. By this means the rear most first stop surface 122a is circular whereas stop surface 122b is annular. Also the third first stop surface 120c is annular and arranged around the mouth of bore 122b.

[0048] In the example shown two of the first stop surfaces 120a, 120b are arranged longitudinally rearward of the front most code position where code surface 116' is arranged.

[0049] As best seen in figs 3b, 3d and 3e, all first stop surfaces 120a-c are positioned in proximity to the lower key blade edge 110. Thus the first stop surfaces 120a, 120b are positioned closer to this lower edge 110 than to the upper edge 112 which is arranged opposite to the lower edge 110 and which comprises the code 114.

[0050] Two 120a-b of the first stop surfaces are also positioned centrally between the two mutually opposite key blade sides 106, 108 and at essentially the same distance from these key blade sides 106, 108 as from the lower edge 110. By this such a central arrangement of the first stop surface 120a, 120b in proximity to the lower edge 110 a comparatively large portion of the height of the key blade sides 106, 108 may be utilized for forming other key blade features such as side codes and profile grooves.

[0051] Fig. 2 illustrates plug 200 of a cylinder lock which forms part of the cylinder lock and key system in which the key shown in figs. 1a-b forms part. Figs. 4a-c illustrates the plug 200 when the key 100 shown in figs 1a-3d has been fully inserted. The plug 200 is intended to be rotationally received in a cylindrical bore of a lock housing (not shown) as is well known in the art. The plug 200 exhibits a front end 202 and a rear end 204. A keyway 206 extends axially from the front end 202 toward the rear end 204 and exhibits a keyway opening at the front end 202. The keyway 106 further extends in one radial direction to the envelope surface of the plug 200 such that the keyway 106 forms a slit in the plug 200. A number of pin tumbler channels 208', 208" are arranged radially in the plug 200 such that they debouch in the keyway 206, one after the other in the axial direction of the plug 200. One pin tumbler channel 208' is positioned rearward of all other pin tumbler channels 208" and thus forms a rear most pin tumbler channel 208'. Each pin tumbler channel 208', 208" receives a radially displaceable pin tumbler (not shown). By insertion of the key blade 104 in the keyway 206, the coded upper key blade edge 112 will contact the inner ends of the pin tumblers and displace the pin tumblers radially in the pin tumbler channels 208', 208". If a correct key blade 104 is fully inserted into the key channel 206 all pin tumblers will be displace to a position where their outer ends are in level with the outer envelope surface 212 of the plug 200, such that the plug may be rotated in the housing (not shown). This functioning of a cylinder lock is well known in the art and is not further described here.

[0052] As seen in figs. 2 and 4b, the plug 200 is provided with two stop members 222a and 222b defining a respective second stop surface 220a, 220b. As best seen in fig. 2 the stop members 222a, 222b are each formed of a cylindrical pin which extends longitudinally in the keyway 206. Each pin 222a, 222b has a forward facing end surface which forms the respective second stop surface 220a, 220b. In the shown example one stop member 222a is arranged as a coaxial extension with reduced diameter of the other stop member 222b. The front most second stop surface 220a, is thereby circular whereas the rear second stop surface 220b of these two second stop surfaces is annular.

[0053] The stop members 222a, 222b are arranged on an insert 230 which further comprises a base portion 232. The base portion is arranged to be removably received in a radially outward open recess 234 which is formed in the plug 200. The radial outer surface 236 of the base portion 232 is convex with the same radius of curvature as the outer envelop surface of the plug 200. When the insert 230 has been positioned in the recess 234 and the plug inserted into the housing (not shown), the insert 230 is form-locked in the recess 234 and may be rotated together with the plug 200.

[0054] The base portion exhibits a forwardly facing surface 238 from which the stop member 222b extends. A annular portion of the forwardly facing surface 238 arranged around stop member 222b forms a third second stop surface 220c, which constitutes a rear most second stop surface.

[0055] As indicated in figs 4a-b, the key 100 is a correct key for the plug 200. When the key 100 is inserted into the keyway 206 it may be advanced until either of the first stop surfaces 120a, 120b, 120c makes contact with a respective second stop surface 220a, 220b, 220c in the keyway 206.

[0056] The key 100 has then assumed the correct fully inserted position whereby code surfaces 116', 116" of the coded edge 112 are correctly aligned with corresponding pin tumblers (not shown) of the plug 200. The pin tumblers are then lifted to a position where their outer ends are in level with the outer envelope surface 212 of the plug 200 and thereby at the shear line between the plug 200 and the housing (not shown). The plug may then be rotated relative to the housing, e.g, by means of turning the key 100.

[0057] In the example shown in figs. 4a-b, only one first stop surface 120b makes contact with the corresponding second stop surface 220b when defining the fully inserted position. It should be noted that, even though it is sufficient that only one pair of first and second stop surfaces, e.g. 120a and 220a or 120b and 220b are arranged to be in contact for defining the fully inserted position, it is also possible that several or all pairs of first and second stop surfaces make simultaneous contact when defining the fully inserted position.. In cases where the key and plug are provided with more than two first and second stop surface any number of pairs of stop surfaces, from one to the number of first and second stop surfaces may be arranged to be in contact for defining the fully inserted position.

[0058] As readily understood, insertion of a key having no first stop surfaces or where the positons of the first stop surfaces do not correctly correspond to the positions of the second stop surfaces of the plug in question, will result in that the key is not correctly positioned in the keyway, when the key blade is stopped by some key blade portion coming in stopping contact with a portion of the plug.

[0059] An advantage of arranging at least one, and as in the shown example two first stop surfaces 120a, 120b behind the front most code surface 116' of the key is that it makes it more difficult for unauthorized persons to produce first stop surfaces by cutting away a front portion of the key blade of an existing key. If a front portion of the key blade is cut away for defining a first stop surface by the cut edge at a certain axial position of the key and if this edge is positioned behind the front most code surface 116', the cut away portion of the key blade will allow the corresponding rear most pin tumbler of the plug to protrude into the keyway when the key has been inserted and rotated 180°. When the key has been so rotated the pin tumbler channels of the housing (not shown) will be aligned with the lower edge 110 of the key blade. With a correct key the lower edge of the key blade 104 will prevent the pin tumblers of the housing to fall or be pushed into the radial opening of the keyway slit. However, if front portion of the key has been cut away, this portion of the key will not prevent such intrusion of cylinder housing pin tumblers into the keyway. Thus at such attempt to unauthorized production a first stop surface the plug will be jammed and the cylinder lock will not function.

[0060] In the cylinder lock and key system, each of the first stop surfaces 120a, 120b 120c on each key comprised in the system may be axially positioned at any one of a predetermined number of possible first stop surface positions. At the system in which the key 100 is comprised, one of the first stop surfaces may be positioned at either of two possible axial positions. The other first stop surfaces may be positioned at any one of two respective possible axial positions. Even though not illustrated in the drawings, plugs comprised in this system are arranged such that each second stop surfaces may be positioned at any one of two corresponding possible second stop surface positions.

[0061] With the shown example it is thus possible to increase the number of system permutations simply by varying the positions of the first 120a, 120b, 120c and the second 220a, 220b, 220c stop surfaces.

[0062] The first and the second stop surface are positioned at any one of a predetermined number of selectable axial positions. Preferably these possible selectable positions are separated by a specific equidistant stop separation distance q, which is equal for all first and second stop surfaces.

[0063] A particular advantage is achieved if the equidistant axial stop separation distance q between the selectable axial positions is chosen with respect to the geometry of the code arranged on the key. Fig. 5a shows in enlarged scale a portion of a key blade 304 of a conventional notched correct key 300 inserted into the plug 400 of a pin tumbler lock. The key blade 304 is provided with a number of code surfaces 351, 352, 353 which are separated axially along the coded edge 312 of the key blade 304. The plug 400 is provided with a corresponding number of code sensing pin tumblers 451, 452, 453 which are axially separated by the same distance as the code surfaces, such that each code surface 351, 352, 353 is radially aligned with a corresponding pin tumbler 451, 452, 453 when the correct key is fully inserted. Each code surface is radially positioned at a certain radial position or code height which is selected out of a number of possible radial positions. These selectable radial positions for the code surfaces are radially separated by an equidistant pitch p. In fig. 5a the pitch (p) is indicated as the radial distance between code surface 351 and 353. These two code surfaces 351, 352 are thus positioned at the smallest possible radial distance between any code surfaces that are not on the same code height. The code surfaces 351, 352, 353 are further arranged as the respective top of a generally truncated equilateral triangular code cut 355. Both sides of the triangular cut 355 exhibits an angle α to the radial direction. This angle α constitutes a code cut angle of the code and is equal for all code surfaces.

[0064] Now, it has proven advantageous to set the stop separation distance q as discussed above to a certain value with regard to the above described geometry of the key code. In the shown example it is advantageous to set the stop separation distance q to a value which is equal to or greater than half of the pitch p multiplied by tan α, i.e.;

[0065] By this means it is assured that the code surfaces of a key comprised in the system but intended not to open this particular lock of the same system will not coincidentally be aligned with any pin tumbler when a key not having the correct first stop surfaces positions in relation to the plug in question is inserted into the plug. Such an incorrect combination is shown in fig. 8b which illustrates the key 300 shown in fig. 5a, when it has been fully inserted into a different cylinder lock 400' of the same system. Also this cylinder lock 400' is provided with pin tumblers 451', 452', 453". However, at this incorrect combination, at least one of the first stop surfaces has made contact with a second stop surface which is displaced axially one stop surface separation distance q from the position at which the second stop surface should be positioned at the plug (e.g. plug 400) for which the key 700 is intended. This stop surface separation distance q is equal to 0,5 * p * tan α.

[0066] A seen in fig 5b, this incorrect combination results in a misalignment between the code surfaces 351, 352, 353 of the key 300 and the corresponding pin tumblers 451', 452', 453' which causes the pin tumblers to be radially displaced out of their releasing position between the plug 400' and the cylinder housing 450'. All shown pin tumblers 451', 452', 453, intersect the shear line S' whereby rotation of the plug 400' is not possible. By selecting the stop surface separation distance q, sufficiently large in relation to the code cut angle α and the pitch p, it is assured that the radial displacement of the pin tumblers 451', 452', 453' is large enough to ensure that the pin tumblers are positioned in an interlocking position between the plug 400' and housing 450' , i.e. a position where the pin tumblers 451', 452', 453' securely intersect the shear line S' between the plug 800'and the housing 450'.

[0067] If e.g. the code cut angle α is 45° and the stop surface separation distance q is larger than 0,5 * p * tan α, the resulting radial displacement of the pin tumbler will be larger than half the pitch. A too small radial displacement could prevent a secure interlocking between the plug and the housing. In particular, manufacturing tolerances and pin tumbler end chamfers or crowning may result in that the pin tumblers, upon rotation of the plug, are forced away from the shear line such that they do not intersect the shear line, thereby incorrectly allowing continued rotation of the plug relative to the housing. With the chosen smallest stop separation distance it is however assured that the pin tumblers will be radially displaced long enough not to allow the pin tumblers to be forced away from the shear line by rotating the key.

[0068] Preferably, the stop surface separation distance q should also be smaller than a certain value to assure that the pin tumblers are not coincidently displace to the next code level. Advantageous q is chosen smaller than or equal to 0,8 * p * tan α. By this means it is assured that using a key with incorrect first stop surfaces does not run the risk of the pin tumblers to be radially displaced a full pitch distance where it could coincidently be positioned such that the pin tumbler does not intersect the shear line. If e.g. the code cut angle α is 45° and the code separation distance q is smaller than or equal to 0,8 * p * tan α, the pin tumblers will be radially displaced a distance which is smaller than or equal to 0,8 * p. At such a limited radial displacement the risk of an end portion of the pin tumblers to be coincidently positioned in proximity to the shear line is eliminated.

[0069] Also at dimpled keys, the same principle for setting the stop separation distance q in relation to the code geometry may advantageously be utilized. In such instances the code cut angle α is the angle between the conically sloping code dimple walls and the central axis of the dimpled code recess.

[0070] In practice, the code cut angle α is, both at sawn or cut keys and at dimpled keys, set within the interval of 40° - 60°.

[0071] It is to be understood that the invention is not limited to the exemplifying embodiments shown in the drawings and described above. Instead the invention may freely be varied within the scope of the appended claims. For instance, in the examples given above the keys and plugs are provided with three first stop surfaces and three second stop surface respectively. Naturally, the keys and plugs may be provided with only two or a higher number of first and second stop surfaces. For each compatible key and plug combination the number of first stop surfaces should preferably correspond to the number of second stop surfaces. The invention may also be varied by varying the predetermined number of selectable axial positions for the first and second stop surfaces. It is also foreseeable that the first stop surfaces may be positioned at any one of a first predetermined number of axial positions whereas the second stop surfaces may be positioned at any one of a second different number of predetermined axial positions. Further more, each of the first stop surfaces may be positioned at any one of a different predetermined number selectable axial positions. Each corresponding second stop surface should then preferably be positioned at any one of a corresponding number of selectable axial positions.

[0072] In the shown examples the first and second stop surfaces are arranged coaxially. It is however also possible that one first stop surfaces is arranged eccentric but still within the longitudinal projection of another first stop surface. At some embodiments the longitudinal projection of two first stop surfaces may be arranged completely non-overlapping. At such embodiments the first stop surfaces are defined by respective bottom surfaces of bores that run longitudinally in parallel next to each other at different heights of the key blades cross section. It is readily understood that the coaxial, overlapping or non-overlapping relationship between the second stop surfaces should correspond to the relationship between the first stop surfaces such that pairs of first and second stop surfaces are arranged aligned in the longitudinal direction of the key blade and the keyway, when a correct key is inserted in the keyway.

Claims

1. A cylinder lock and key system including,

cylinder locks of the kind comprising

a housing having a cylindrical bore; and

a cylindrical plug (200, 400) which is rotatably journaled in the housing about a rotational axis and which exhibits a front end and a keyway (206), which extends axially from an entrance opening at the front end; and

keys (100, 300) of the kind comprising

a key bow (102,); and

a key blade (104, 304) extending forwardly from the key bow to a key tip, which key blade is insertable in a forward longitudinal direction to a fully inserted position in the keyway of corresponding locks and rotatable about the rotational axis when inserted;

wherein the plugs and keys are provided with cooperating stop surfaces for defining the fully inserted position of the keys in the keyways, which cooperating stop surfaces comprise

- at least two first stop surfaces (120a, 120b) arranged at the key blade (104) of each key, each first stop surface facing forward in the insertion direction and being positioned at a selected one of a predetermined number of selectable axial positions, and

- at least two second stop surfaces (220a, 220b) arranged in the keyway (206) of each plug, each second stop surface being positioned at a selected one of the predetermined number of selectable axial positions; and

wherein the first and second stop surfaces are arranged such that at least one first stop surface is in contact with a corresponding second stop surfaces when a correct key is fully inserted in the keyway of a corresponding lock,
characterized in that
at least two first stop surfaces (120a, 120b) are defined by a bottom surface of a respective bore (122a, 122b) which extends longitudinally into the key blade (104) from a key tip portion (105) and in that
at least two second stop surfaces (220a, 220b) are defined by an end surface of a respective stop member (222a, 222b) which extends longitudinally into the keyway (206) from a rear portion of the plug (200).

2. A cylinder lock and key system according to claim 1, wherein at least one of said bottom surfaces is arranged within the longitudinal projection of another of said bottom surfaces.

3. A cylinder lock and key system according to claim 2, wherein at least two of said bores (122a, 122b) are co-axial.

4. A cylinder lock and key system according to any of claims 1-3, wherein the at least one of said bores (122a, 122b) is cylindrical.

5. A cylinder lock and key system according to any of claims 2-4, wherein at least one (222a) of said stop members is arranged as a longitudinal extension of another (222b) of said stop members.

6. A cylinder lock and key system according to any of claims 3-5, wherein at least two of said stop members (222a, 222b) are co-axial.

7. A cylinder lock an key system according to any of claims 1-6, wherein at least one of said stop members (222a, 222b) is cylindrical.

8. A cylinder lock and key system according to any of claims 1-7, wherein at least two of said stop members (222a, 222b) are arranged on an exchangeable component (230) which is removably fixed to the plug (200).

9. A cylinder lock and key system according to any of claims 1-8, wherein the keys (100) are provided with a number of code surfaces (116', 116") arranged one after the other in the longitudinal direction of the key blade (104); and the plugs (200) are provided with radially displaceable pin tumblers, each code surface being arranged to cooperate with a corresponding pin tumbler when the key blade (304) is fully inserted in the keyway (206), and wherein at least one first stop surface (120a, 120b) is positioned longitudinally rearward of the front most code surface (116').

10. A cylinder lock and key system according to any of claims 1-9, wherein the key tip portion (105) exhibits a forwardly facing front edge (123) and wherein at least one of said bores (122b) debouch at said front edge.

11. A cylinder lock and key system according to any of claims 1-10, wherein at least one key is a reversible key, the key blade of which exhibits at least two primary first stop surfaces and at least two secondary first stop surface; and wherein the primary and secondary first stop surfaces are arranged symmetrically with regard to a longitudinal centre axis of the key blade.

12. A cylinder lock and key system according to any of claims 1-11, wherein the keys (300) are provided with a code arranged at the key blade (304) for cooperating with corresponding pin tumblers (451, 452, 453) of the plugs (400), which code exhibits a code cut angle α and code surfaces (351, 352, 353) which are radially separated by an integer multiple of a code surface pitch, p, and wherein the selectable axial positions for the first and second stop surfaces are axially separated by a stop separation distance q, wherein q ≥ 0,5 * p * tan α.

13. A cylinder and lock and key system according to any of claims 1-12, wherein the first stop surfaces are positioned closer to a key blade edge (110) which is arranged opposite to an edge (112) comprising a code (114), than to the edge comprising the code.

14. A cylinder and lock and key system according to any of claims 1-13, wherein the first stop surfaces are positioned centrally between two mutually opposite key blade sides (106, 108) and at essentially the same distance from said key blade sides as from an edge (110) being arranged opposite to to an edge (112) comprising a code(114).

15. A cylinder lock and key combination including,

a cylinder lock comprising

a housing having a cylindrical bore; and

a cylindrical plug (200, 400) which is rotatably journaled in the housing about a rotational axis and which exhibits a front end and a keyway (206) having opposite keyway sides and a height direction which is parallel with the keyway sides and perpendicular to the rotational axis, which keyway extends axially from an entrance opening at the front end; and

a key (100, 300) comprising

a key bow (102); and

a key blade(104, 304) extending forwardly from the key bow to a key tip which key blade is insertable in a forward longitudinal direction to a fully inserted position in the keyway of corresponding locks and rotatable about the rotational axis when inserted;

wherein the plug and key are provided with cooperating stop surfaces for defining the fully inserted position of the key in the keyway, which cooperating stop surfaces comprise

- at least two first stop surfaces (120a, 120b) arranged at the key blade (104), each first stop surface facing forward in the insertion direction; and

- at least two second stop surfaces (220a, 220b) arranged in the keyway (206) of the plug (200), each second stop surface facing forward relative to the plug; and

wherein the first and second stop surfaces are arranged such that at least one first stop surface is in contact with a corresponding second stop surfaces when the key is fully inserted in the keyway of the lock,
characterized in that
at least two first stop surfaces (120a, 120b) are defined by a bottom surface of a respective bore (122a, 122b) which extends longitudinally into the key blade (104) from the key tip portion (105) and in that
at least two second stop surfaces (220a, 220b) are defined by an end surface of a respective stop member (222a, 222b) which extends longitudinally into the keyway (206) from a rear portion of the plug (200).

16. A key (100, 300) for a cylinder lock and key system according to any of claims 1-14, which key comprises a key bow (102) and a key blade (104, 304) extending forwardly from the key bow to a key tip, which key blade is insertable to a fully inserted position in a keyway of corresponding locks and rotatable about a rotational axis when inserted, which key blade is provided with at least two first stop surfaces (120a, 120b) which are arranged to define the fully inserted position of the key in the keyway by contacting corresponding second stop surfaces arranged in the keyway of a lock, characterized in that at least two first stop surfaces (120a, 120b) are defined by a bottom surface of a respective bore (122a, 122b) which extends longitudinally into the key blade (104) from a key tip portion (105).

17. A key blank for producing a key according to claim 16, which key blank comprises a key bow and a key blade extending forwardly from the key bow to a key tip, wherein at least two first stop surfaces are arranged at the key blade for defining a fully inserted position of a key produced from the key blank in a keyway of a cylinder lock and at least two first stop surfaces, each first stop facing forward, characterized in that at least two first stop surfaces are defined by a bottom surface of a respective bore which extends longitudinally into the key blade from a key tip portion.

18. A cylinder lock for a system according to any of claims 1-14, which cylinder lock comprises a housing having a cylindrical bore and a cylindrical plug (200, 400) which is rotatably journaled in the housing about a rotational axis and which exhibits a front end (202) and a keyway (206) which extends axially from an entrance opening at the front end and which is arranged to receive a corresponding key which is insertable to a fully inserted position in the keyway, wherein the plug is provided with at least two second stop surfaces (220a, 220b) which are arranged to define the fully inserted position of the key in the keyway by contacting corresponding first stop surfaces arranged at the corresponding key characterized in that at least two second stop surfaces (220a, 220b) are defined by an end surface of a respective stop member (22a, 22b) which extends longitudinally into the keyway (206) from a rear portion of the plug (200).

Drawing