Flat key with copy protection

Abstract

The invention relates to a flat key (1) with a key bow (2) and a key shaft (3) for a lock-key system, in which a key channel corresponding to a key profile of the key shaft (3) is provided in a locking cylinder (20), wherein the key shaft (3) has a key back (4), a key tip, two key side surfaces (5, 6) and a key breast (7), wherein the key profile has a paracentric shoulder (8) on the key breast side and the paracentric shoulder (8) is formed by an outer surface (8a) and an inner surface (8b), in particular wherein the outer surface (8a) is substantially formed by one of the two key side surfaces (5, 6) and the inner surface (8b) is arranged parallel to the outer surface (8a), wherein the inner surface (8b) has a distance (b) to the central plane (9) of the key shaft (3), in particular flat key (1), in the range of 0.2 mm to 0.3 mm.

Description

[0001] The invention relates to a flat key with copy protection based on a paracentric shoulder. Furthermore, the invention also relates to a lock-key system.

[0002] Nowadays, conventional flat keys are copied or imitated for a variety of reasons. This is not always done legally. Manufacturers of lock-key systems generally pursue the approach that a replacement key can be purchased either by ordering it from the manufacturer or through a certified locksmith. Such certified locksmiths generally use original manufacturer blanks in conjunction with a security card, which can be used to create a replacement key. Furthermore, these locksmiths are licensed to duplicate the keys. However, there are a variety of universally applicable key profile copying machines on the market, for example, the EasyEntrie from Keymax, Bad Saulgau, Germany. With such copying machines, anyone can copy or duplicate conventional flat key profiles.

[0003] From DE 197 07 932 A1 a flat key is known in which the profile ribs have curved cross-sectional contours to avoid sharp edges.

[0004] From DE 10 2005 036 113 A1 a flat key is known in which grooves are cut starting from the flat sides, whereby the angles of the grooves are selected in such a way that sharp-edged arms are avoided.

[0005] Flat key profiles with different profile grooves are known from DE 10 2018 101 438 A1.

[0006] From CH 718958 A1 a flat key with coding holes and a method for its production are known.

[0007] Various key manufacturing processes are known from DE 601 30 230 T2.

[0008] It is therefore the object of the present invention to provide a flat key which has increased copy protection compared to conventional flat keys and which cannot be copied by conventional key profile copying machines.

[0009] This object is achieved according to the invention by a flat key having the features of claim 1.

[0010] According to the invention, a flat key with a key bow and a key shank is provided for a lock-key system, in which a key channel corresponding to a key profile of the key shank is provided in a locking cylinder, wherein the key shank has a key back, a key tip, two key side surfaces and a key breast, wherein the key profile has a paracentric shoulder on the key breast side and the paracentric shoulder is formed by an outer surface and an inner surface, in particular wherein the outer surface is formed substantially by one of the two key side surfaces and the inner surface is arranged parallel to the outer surface.

[0011] What is essential in the flat key according to the invention is that the inner surface has a distance from the center plane of the key shaft, in particular the flat key, in the range of 0.2 mm to 0.3 mm.

[0012] The term “key breast side” preferably means that the paracentric shoulder is formed starting from the key breast.

[0013] The key side surface is preferably understood to be an outer surface of the flat key, which may comprise one or more partial surfaces. For example, a key side surface may have one or more profile features in the form of profile grooves, shoulders, notches, etc. In this case, several partial surfaces of the key side surface are preferably formed.

[0014] Paracentric preferably refers to an off-center profile feature that preferably extends beyond the center plane of the flat key. However, it is also possible for the off-center profile feature not to extend beyond the center plane, but rather from a key side surface not to the center plane. In this case, too, a paracentric profile feature is assumed. In particular, the paracentric step is a step that extends along the insertion direction when viewed from the cross-section of the flat key or when viewed from the front at the key tip.

[0015] Typically, a key copy is made with a smaller thickness than the original key. This ensures that the key copy can be inserted into the keyway of the locking cylinder.

[0016] The paracentric shoulder ensures that the core pins of the locking cylinder, which interact with the paracentric shoulder, are interrogated off-center rather than centrally as with conventional flat keys. The core pins are preferably interrogated at a distance from the center plane determined by the paracentric shoulder. The top of the core pins is generally curved or domed. This means that if the core pin were interrogated centrally, it would be interrogated at its highest point. Due to the curved or domed top, the core pin is no longer interrogated at its highest point in the case of an off-center interrogation.

[0017] The paracentric shoulder of the flat key now provides copy protection in that the specified distance of the paracentric shoulder to the center plane is changed in the key copy due to its smaller thickness compared to the original key. This means that when the key copy is inserted into the locking cylinder, the core pins are no longer interrogated at the specified distance, but at a different distance. As a result, due to their curved or dome-shaped upper sides, the core pins are either no longer pressed in far enough or are even pressed in too far, depending on whether the key copy is interrogated more centrally or more off-center. In both cases, the underside of the core pins misses the parting plane. This means that locking and closing the lock with the key copy is no longer possible.

[0018] Furthermore, the paracentric heel offers a further advantage in compliance with DIN 18252 ( " Profile cylinders for door locks - Terms, dimensions, requirements, marking"; DIN 18252:2018-05; Publication date: 2018-05). Since the paracentric shoulder preferably represents the notch area, i.e., the area in which the notches are provided, and simultaneously represents one of the paracentric profile features required by DIN 18252, only two additional paracentric profile features need to be provided above the notch area instead of three. This offers the possibility of arranging more variable profile features above the notch area or above the paracentric shoulder.

[0019] The distance between the inner surface and the center plane is preferably the specified distance described above. If the flat key were copied, this distance would no longer be maintained. For example, the distance of the key copy would always be more than 0.3 mm. In this case, the core pin of the locking cylinder would no longer be interrogated at the predefined position, resulting in the core pin not being pushed in far enough. The underside of the core pin would therefore no longer reach the parting plane of the locking cylinder, and locking the lock with a key copy would not be possible.

[0020] In a preferred embodiment, the paracentric shoulder can extend in the direction of key insertion of the flat key. Preferably, the paracentric shoulder extends over the entire length of the key shaft. This ensures that several core pins arranged in the locking cylinder can be interrogated with the paracentric shoulder over the entire length of the key shaft.

[0021] It can also be provided that the paracentric shoulder extends from the key face toward the key spine, in particular, wherein the extension has a height in the range of 2 mm to 5 mm, preferably 3 mm to 4 mm. In particular, when considering the cross-section of the flat key, the paracentric shoulder is understood to be a rectangular profile having a height and a width. The width preferably extends from the outer surface to the inner surface of the paracentric shoulder.

[0022] In particular, it is provided that the paracentric shoulder has two or more notches, in particular wherein the two or more notches originate from the key face and preferably extend across the entire width of the paracentric shoulder. Notches are preferably triangular incisions that can be seen when viewed vertically from one of the key side surfaces of the flat key. The paracentric shoulder can preferably have 2 to 10 notches, more preferably 3 to 8 notches, and especially preferably 4 to 7 notches.

[0023] The notches of the parametric shoulder preferably interact with the core pins of the locking cylinder. Each notch preferably interacts with a corresponding core pin. Depending on the depth or height of the notches, different core pin lengths are used to ensure that the undersides of the core pins always reach the parting line.

[0024] In a preferred embodiment, at least one profile groove can be provided on one or both key side surfaces, extending in the key insertion direction of the flat key. In other words, the at least one profile groove runs parallel to the key spine and preferably extends over the entire length of the key shank. For example, 1 to 12, preferably 2 to 10, more preferably 3 to 8, profile grooves can be provided.

[0025] Furthermore, it can preferably be provided that the at least one profile groove is paracentric. This preferably means that the profile groove has a profile depth that extends beyond the center plane of the flat key. Preferably, three, four, or five paracentric profile grooves are provided. It may also be possible to provide additional non-paracentric profile grooves in combination with the paracentric profile grooves.

[0026] The invention can also encompass a lock-key system, in particular a lock-key system with a lock cylinder and a flat key according to one of the embodiments described herein. In particular, the lock cylinder has a keyway corresponding to a key profile of the key shaft and core pins for interrogating key notches of the key profile of the flat key.

[0027] Furthermore, the invention can also encompass a method for producing a flat key according to one of the embodiments described herein. In particular, it is provided that a key blank is provided, and the flat key is produced by machining, in particular by milling, the key blank.

[0028] Alternatively or additionally, a method for producing a flat key according to one of the embodiments described herein can be provided, wherein a digital 3D model of the flat key is provided and the flat key is produced by 3D printing based on the digital 3D model, in particular by selective laser melting (SLM). The digital model of the flat key can be provided by the manufacturer as a file. The digital model of the flat key can also be created by scanning a model or a flat key.

[0029] The flat key according to the invention is used in almost all cylinder lock systems for house, apartment, or building doors. Due to its design, the flat key offers mechanical copy protection, since a key copy made using conventional key-copying machines can no longer lock the locking cylinder. The key copy is therefore unusable. This prevents, among other things, the illegal duplication of flat keys by uncertified key services.

[0030] The invention is explained below using several exemplary embodiments with the aid of the accompanying drawings. The exemplary embodiments shown are therefore not to be understood as limiting. Fig. 1 shows a schematic representation of a three-dimensional image of a flat key. Fig. 2 shows a schematic representation of a side view of a flat key. Fig. 3 shows a schematic representation of a cross-section of a flat key. Fig. 4 shows a schematic representation of a cross-section of a locking cylinder with an inserted flat key. Fig. 5 shows a diagram in which the core pin position is plotted against the paracentricity of the paracentric shoulder of the flat key.

[0031] The figures illustrate various examples of embodiments of the invention. Identical or equivalent components have been provided with the same reference symbols. Where the embodiments illustrated in the figures have common features, these common features have been omitted from being described multiple times to avoid repetition. The respective differences between the embodiments are described in relation to the figures. It goes without saying that a person skilled in the art can modify individual embodiments or combine individual features of these embodiments within the scope of the claims.

[0032] Fig. 1 shows a schematic representation of a three-dimensional image of a flat key 1. The flat key 1 has a key blade 2 and a key shaft 3. The key shaft 3 is preferably formed integrally with the key blade 2. It is preferably possible for the key blade 2 to be thicker than the key shaft 3, or vice versa.

[0033] The key shank 3 has a key back 4, a key tip, two key side surfaces 5, 6, and a key face 7. Preferably, the key shank 3 forms a key profile that corresponds to a key channel of a locking cylinder 20.

[0034] Fig. 2 shows a schematic representation of a side view of a flat key 1. The Fig. 2 The flat key 1 shown corresponds to the Fig. 1 shown flat key 1. Thus, in Fig. 2 a vertical view of one of the key side surfaces 5, 6 of the flat key 1. The Fig. 2 The flat key 1 shown has a key profile in which a paracentric shoulder 8 is provided on the key face side. The paracentric shoulder 8 is preferably visible when viewed in cross section and can also be formed by several notches 10, as in Fig. 2 indicated, be trained.

[0035] In Fig. 3 is a schematic cross-section of the flat key 1, in particular of the key shaft 3, at the position of Fig. 2 shown section line. Essentially, the cross section of the flat key 1 or the key shaft 3 is formed by the key back 4, the two key side surfaces 5, 6 and the key face 7. As shown in Fig. 3 As shown, the two key side surfaces 5, 6 are each interrupted by a profile groove 11, 12. Preferably, the profile grooves 11, 12 extend in the key insertion direction of the flat key 1. This means that the profile grooves 11, 12 run parallel to the key back 4 and preferably extend over the entire length of the key shank 3. The profile grooves 11, 12 preferably represent additional profile features that further increase the copy protection of the flat key 1.

[0036] In a preferred embodiment, the at least one profile groove 11, 12 can be paracentric. This means that the profile groove 11, 12 has a profile depth that extends at least beyond the center plane 9 of the flat key 1.

[0037] Furthermore, in the Fig. 3 The cross-sectional view of the flat key 1 shown shows the paracentric shoulder 8, which is formed by an outer surface 8a and an inner surface 8b. In the embodiment shown, the outer surface 8a is essentially formed by the key side surface 5, and the inner surface 8b is arranged parallel to the outer surface 8a. Alternatively, it can also be provided that the outer surface 8a of the paracentric shoulder 8 is formed by the key side surface 6. In an alternative embodiment, it is also possible for the inner surface 8b and the outer surface 8a not to be arranged parallel to one another, but rather, for example, to be arranged at an angular offset.

[0038] As mentioned at the beginning, paracentric refers to an off-center arrangement of a component. As in Fig. 3 As shown, the inner surface 8b of the paracentric shoulder 8 is arranged at a distance b from the center plane 9 of the key shank 3. Preferably, the distance b is in a range of 0.2 mm to 0.3 mm.

[0039] As in Fig. 1 und Fig. 2 As shown, the paracentric shoulder 8 preferably extends in the key insertion direction of the flat key 1. It can be provided that the paracentric shoulder 8 extends over the entire length of the key shaft 3.

[0040] Furthermore, the paracentric shoulder 8 extends from the key breast 7 in the direction of the key back 4. The extension preferably has a height a in the range of 2 to 5 mm, preferably from 3 mm to 4 mm.

[0041] As already mentioned Fig. 2 As explained, the paracentric shoulder 8 can have two or more notches 10, in particular wherein the two or more notches 10 emanate from the key breast 7 and preferably extend over the entire width of the paracentric shoulder 8. The term width is understood to mean the extension of the paracentric shoulder 8 from its outer surface 8a to the inner surface 8b. The notches 10 preferably interact with the core pins 23 and are thus intended to ensure that the core pins 23 of the locking cylinder 20 are pressed in as far as the parting plane, so that closing or locking of the locking cylinder is possible. In the case of a key copy which, as mentioned at the beginning, is thinner than the original key, the core pins 23 are interrogated by means of the notches 10 in a different position than in the original, which is why locking or closing of the locking cylinder is no longer possible.

[0042] In Fig. 4 is a schematic representation of a cross section of a locking cylinder 20 with inserted flat key 1, as shown for example in the Fig. 1-3 shown. The locking cylinder 20 comprises a cylinder housing 21, in the bore of which a cylinder core 22 is rotatably mounted. A keyway is provided in the cylinder core 22 itself, into which a corresponding flat key 1 can be inserted. Along the center plane 9, one or more pin bores are provided vertically from below in both the cylinder housing 21 and the cylinder core 22, which are arranged along the insertion direction of the flat key 1. In this case, a housing pin 24 is arranged in each of the pin bores in the cylinder housing 21, and a core pin 23 is arranged in each of the pin bores in the cylinder core 22. In this case, one core pin 23 interacts with one housing pin 24 each, thus forming a pin pair.

[0043] Preferably, it can be provided that each housing pin 24 interacts with a spring (not shown) in the cylinder housing 21. The spring ensures that the housing pin 24, together with the core pin 23, is brought into a zero position.

[0044] If a flat key 1 is now inserted into the keyway, the core pins 23 are displaced or pressed downward due to the key profile. The core cylinder can only be locked or unlocked by rotation with the flat key 1 if all undersides of the core pins 23 are essentially congruent with the parting plane within the manufacturing tolerances. Conversely, this also means that all upper sides of the housing pins 24 are essentially congruent with the parting plane within the manufacturing tolerances.

[0045] As already explained above, the notches 10 of the flat key 1, which are arranged along the paracentric shoulder 8, interact with the core pins 23 of the locking cylinder 20. This is also shown in the cross-sectional view according to Fig. 4 illustrated. In cross-section, the paracentric shoulder 8 is in contact with the upper surface of the core pin 23. The upper surface of the core pin 23 is not flat, but rather curved and / or tapered. The contact between the paracentric shoulder 8 or notches 10 and the upper surface of the core pin 23 preferably always forms a linear and bilateral contact.

[0046] As in Fig. 4 As shown, the contact is paracentric, i.e., off-center. In conventional flat keys 1, the contact between the notches of the key and the top of the core pin 23 is usually centric, i.e., the notches touch the core pin at its highest point.

[0047] As mentioned at the beginning, key copies are generally made thinner than the original to ensure that the key copy can always be inserted into the keyway. With conventional keys, whose contact with the core pin 23 is centered, a thinner, copied key can still reliably activate the cylinder lock's locking mechanism, since even with a thinner key copy, the contact with the core pin 23 is always centered. This is due to the fact that the notches of the key copy are always arranged on the center plane 9 of the key, even with a thinner thickness.

[0048] However, if a thinner key copy is made from a flat key 1 according to the invention with a paracentric shoulder 8, the distance b of the paracentric shoulder 8 to the center plane 9 of the flat key 1 increases in the key copy compared to the original key due to the reduction in thickness. Due to the increased distance b, the contact between the key copy and the core pin 23 no longer corresponds to the contact between the original key and the core pin 23. This means that the contact is more off-center in the key copy than in the original. The core pin 23 is therefore no longer pressed downwards far enough and therefore no longer reaches the parting plane. This makes it impossible to close the locking cylinder.

[0049] Fig. 5 shows a diagram in which the core pin position is represented by the paracentricity of the paracentric shoulder 8 of the flat key 1. The paracentricity is preferably defined as distance b, as for example in Fig. 3 As already mentioned, Fig. 3 As explained, the distance b is preferably in a range of 0.2 mm to 0.3 mm. Using the diagram according to Fig. 5 It is evident that the core pin position increases with larger distances. From distances greater than 0.3 mm, the change in the core pin position increases significantly. Furthermore, at distances greater than 0.3 mm, there is a high risk that the core pin 23 will tilt in the core bore due to the off-center contact point with the paracentric shoulder 8. In this case, the locking function of the locking cylinder begins to jam and may no longer be able to be operated. List of reference symbols

[0050] 1Flat key 2Key blade 3Key shank 4Key back 5, 6Key side surfaces 7Key face 8Paracentric shoulder 8aOuter surface 8bInner surface 9Center plane 10Notch 11, 12Profile groove 20Locking cylinder 21Cylinder housing 22Cylinder core 23Core pin 24Housing pin aHeight bDistance

Claims

1. A flat key (1) with a key blade (2) and a key shank (3) for a lock-key system, in which a key channel corresponding to a key profile of the key shank (3) is provided in a locking cylinder (20), wherein the key shank (3) has a key back (4), a key tip, two key side surfaces (5, 6) and a key breast (7), wherein the key profile has a paracentric shoulder (8) on the key breast side and the paracentric shoulder (8) is formed by an outer surface (8a) and an inner surface (8b), in particular wherein the outer surface (8a) is formed substantially by one of the two key side surfaces (5, 6) and the inner surface (8b) is arranged parallel to the outer surface (8a), characterized by that the inner surface (8b) has a distance (b) from the center plane (9) of the key shaft (3), in particular the flat key (1), in the range of 0.2 mm to 0.3 mm.

2. Flat key (1) according to claim 1, characterized by that the paracentric shoulder (8) extends in the key insertion direction of the flat key (1).

3. Flat key (1) according to one of the preceding claims, characterized by that the paracentric shoulder (8) extends from the key breast (7) in the direction of the key back (4), in particular wherein the extension has a height (a) in the range from 2 mm to 5 mm, preferably from 3 mm to 4 mm.

4. Flat key (1) according to one of the preceding claims, characterized by that the paracentric shoulder (8) has two or more notches (10), in particular wherein the two or more notches (10) emanate from the key face (7) and preferably extend over the entire width of the paracentric shoulder (8).

5. Flat key (1) according to one of the preceding claims, characterized by thatat least one profile groove (11, 12) is provided on one or both key side surfaces (5, 6), which extends in the key insertion direction of the flat key (1).

6. Flat key (1) according to claim 5, characterized by that at least one profile groove (11, 12) is paracentric.

7. Lock-key system comprising a locking cylinder (20) and a flat key (1) according to one of the preceding claims, wherein the locking cylinder (20) has a key channel corresponding to a key profile of the key shaft (3) and core pins (23) for interrogating key notches of the key profile of the flat key (1).

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