Patent Description:
A disc tumbler cylinder lock is a widely used lock structure which comprises a fixed outer cylinder, inside which there is an inner cylinder. Inside the inner cylinder there are a number of tumbler discs arranged as a pack of discs to be rotated with a key of the lock from their locking positions to opening positions. Each tumbler disc comprises a circumferential notch, a key opening corresponding to the cross-sectional profile of the key so as to form a key passageway, and a circumferential limiter which, in cooperation with a rotation opening of the inner cylinder, is arranged to limit the path of movement of the disc tumbler to a specific circular sector. In addition, the lock comprises a tumbler bar which in a locked position locks the inner cylinder to the outer cylinder. When the circumferential notches of all tumbler discs are rotated to the position of the tumbler bar, the tumbler bar is arranged to free the inner cylinder to rotate relative to the outer cylinder for opening the lock in a way that the tumbler bar is received in the groove formed by the circumferential notches.

The opening combinations of the disc tumbler cylinder lock amount to millions, but they still are limited. A number of additional combinations have therefore been developed by using keys of a different cross-sectional profile, whereby only a specific key profile fits in the key opening extending through the tumbler discs.

The keys of different lock models use a different number of evenly spaced notches having a standard angle which are made by key cutters manufactured for this purpose. Thus, for example in the ASSA Abloy company's key series Classic®, Exec® and Sento®, only notches corresponding to tumbler disc angles <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>° are cut on the keys. As to the key series Protec®, the notches to be cut on the keys correspond to tumbler disc angles <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>°.

As the variations increase, misopenings in the lock sets increase as well, and locks will open by keys that do not belong to the lock set. For example, residents of an apartment building will have access with their own keys to the apartments of a neighbouring building. The misopenings of lock sets are attempted to be controlled for example with software based on automatic data processing whereby, after the computed variations are complete, it is no more possible to rekey the series in the lock sets. Thus, the only option is to renew the lock set as a whole. Renewing a lock set is a very expensive and difficultly predictable operation.

Examples of a disc tumbler cylinder lock and a key for said lock are presented in documents <CIT> and <CIT>.

To remedy the problems with current technology, the number of code tumblers should be raised and all machines and devices on the market for making keys should be replaced with machines and devices that would allow the making of cuts on the keys corresponding to the new tumblers. The invention is also related to a lock assembly device used for making tumbler discs which is disclosed in international patent application <CIT>. The compact lock assembly device enables quick making of tumbler discs regardless of place with accurate and exact notch machining.

The objective of the invention is to remedy the defects of the prior art mentioned above. Specifically, the objective of the invention is to disclose a novel technique for extending the size of lock sets and continuing their lifespan in a safe way without increasing the misopening possibilities.

In the method according to the invention for making a key of a disc tumbler cylinder lock, the key is cut to have lock-model-specific standard angle notches corresponding to tumbler discs of the lock for rotating, when the key is turned in the lock, the tumbler discs of the lock to certain lock-model-specific standard rotation angles. According to the invention, the key is provided with a shape for rotating, when the key is turned in the lock, at least one tumbler disc of the lock to a position that differs from its lock-model-specific standard rotation angles for multiplying the variations of the lock.

The differing shape according to the invention is made in one embodiment of the invention before cutting the lock-model-specific standard angle notches. Thus, the key blank already has the differing shape when it is cut to have the lock-specific notches.

In a second embodiment of the invention, the shape is made at the same time with cutting the lock-model-specific standard angle notches. However, this requires that the existing cutter machines are modified in ways that such shape that differs from the standard notches can be made.

In a third embodiment, the shape is made after cutting the lock-model-specific standard angle notches. When the above-mentioned inventive shape is made at a different time than the lock-model-specific standard angle notches, they can be made with other cutters or corresponding machines so as to avoid modifications of the standard cutter machines.

Depending on the embodiment, the shape according to the invention can be made by cutting a notch on the shank of the key or by shaping the shank of the key or by adding the shape to the shank of the key. The essential feature is that the shape forms a notch having an angle that differs from the lock-model-specific standard angle notches, i.e. the shape rotates one or more tumbler discs to an angle to which they cannot be rotated by any of the standard angle notches.

The invention further relates to a key blank comprising a bow and a shank. According to the invention, the shank comprises a shape arranged to rotate at least one tumbler disc of a disc tumbler cylinder lock corresponding to the key blank to a position that differs from lock-model-specific standard rotation angles.

The shape according to the invention may be in a series lock set area, i.e. in the area for cutting a series lock set notch. The shape may also be immediately after an area of a raising zero at the tip of the shank of the key blank.

The shape according to the invention preferably has an angle approximately halfway between standard cutter angles. Depending on the lock sets, the standard cutter angles are the angles <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>° or the angles <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>°. It is not obligatory that the angle of the notch with the inventive shape is halfway between standard angles, but it is sufficient that this shape differs to a notable degree from the standard angles, i.e. that malfunctions in the lock are not able to occur. In general, in precision-made disc tumbler cylinder locks it is sufficient to have even a difference of one degree from the standard angles to differentiate between operations of the locks.

The invention further relates to a series key comprising a bow and a shank as well as lock-model-specific standard cutter angle notches cut on the shank and corresponding to tumbler discs of a lock that corresponds to the profile of the shank. According to the invention, the series key comprises a shape that differs from said notches, arranged to rotate at least one tumbler disc of the lock to a position that differs from the lock-model-specific standard rotation angles. The inventive shape mentioned above may be a notch or a projection.

Preferably, the shape has an angle which is approximately halfway between standard cutter angles. The lock-model-specific standard cutter angles may be the angles <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>° or the angles <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>°.

The invention further relates to a combination of a disc tumbler cylinder lock and a key. According to the invention, the series key comprises a shape that differs from said notches, arranged to rotate at least one tumbler disc of the lock to a position that differs from the lock-model-specific standard rotation angles.

The method, key blank and series key according to the invention have notable advantages over the prior art. The size of lock sets can be extended and their lifespan continued in a safe way by means of the invention without increasing misopenings. When the combinations of a specific lock set have been used up, it is possible to bring into use a completely new lock set, i.e. a new lock set in the old lock set, by using a single shape that differs from the standard angles in the keys. This is done in the simplest way by making such differing notch already in the key blanks. Then, the normal standard angle notches can be made with the existing standard cutter machines on the blank provided with such a notch so that they do not fit in any existing locks already in use. A new lock cylinder with new tumbler discs is then made by filling uncut tumbler discs in the inner cylinder of the lock, by rotating, with the new key, the tumbler discs to the opening position determined by the key, and by cutting the rotated tumbler discs to have a notch for a tumbler bar as described in more detail in the above-mentioned international patent application <CIT> Even a single new notch or other shape that differs from the standard angles doubles the number of different combinations for use in the lock set. When the angle of this notch in changed and it is maintained different from the standard angles, yet another new combination series is obtained. For example, with factory-made key blanks it is thus possible, by changing the angle of a single notch, to multiply the number of different locking combinations of the same lock series in a safe and secure way. The safety of widely used and old lock series is even increased by the invention, because the keys are provided with notch angles which, with the normal key cutters as such, are not even possible to be made.

The invention will now be described in detail with reference to the accompanying drawings, in which.

<FIG> illustrates a conventional key blank which comprises a bow <NUM> and a shank <NUM>. Such uncut key blanks with a smooth shank are used by locksmithing stores when they make keys for locks with their cutter machines.

<FIG> illustrates the key blank according to the invention, which also comprises a plate-shaped bow <NUM> and a cross-sectionally semicircular shank <NUM>. However, the shank <NUM> is already beforehand in factory conditions or otherwise before making the actual tumbler notches machined to have a shape <NUM>, i.e. a notch in this embodiment. The angle <NUM> of the notch, shown at the tip of the key blank in a dotted line, differs from all angles which are used in a lock model corresponding to this key as tumbler notches.

In <FIG>, tumbler notches have been made on the key blank of <FIG>, i.e. the key is ready. The angles of the tumbler notches vary along the shank as follows: the angle of a first notch <NUM> is <NUM>°,.

The last one before an area <NUM> of a raising zero is the new and inventive shape <NUM> already provided on the blank as shown in <FIG>, i.e. a notch with an angle of approximately <NUM>° in this embodiment. Thus, the angle of this notch <NUM> is such that it does not appear in any standard tumbler notches of this lock model, which are <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>°. <NUM>° is just about in the middle of the last two angles, i.e. <NUM>° and <NUM>°.

Thus, by making a key having a tumbler notch with a differing angle which rotates a corresponding tumbler disc of the lock in a differing way, a completely new lock series for use in an existing lock set is obtained. It is completely safe to bring all key combinations used previously in this lock set into use again, because the keys are made new and unique due to the new notch <NUM> that differs from the other notches. In this embodiment, this new and inventive notch <NUM> is made immediately after the area <NUM> of the raising zero before the actual tumbler notch area of the key. However, there is no objection to making this new and differing notch in the actual tumbler notch area, i.e. as one of these ten tumbler notches.

Because the angle of the notch <NUM> differs from the conventional angles, it cannot be made with the existing key cutter machines. It is therefore made already beforehand on the key blank according to the invention. Locksmiths are thus provided with key blanks having one notch with a differing angle for making the keys. When the tumbler notches of the key are cut, the tumbler discs of the lock can be made with the device and method according to the above-mentioned international patent application <CIT>. The locksmith will therefore only need basic tumbler discs free of the notches for a tumbler bar and key blanks according to the invention provided with the differing notch <NUM>, and thereby new lock series can be created and even large lock sets safely rekeyed without the risk that the keys would fit in inappropriate locks.

Claim 1:
A combination of a disc tumbler cylinder lock and a key, wherein
the disc tumbler cylinder lock comprises tumbler discs having lock-model-specific standard rotation angles,
the key comprises a bow (<NUM>) and a shank (<NUM>) as well as lock-model specific standard cutter angle notches (<NUM>-<NUM>) cut on the shank and corresponding to tumbler discs of the lock that corresponds to the profile of the shank,
wherein standard cutter angles are <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>°, or <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>°,
characterized in that the key comprises a shape (<NUM>) that differs from said notches, arranged to rotate at least one tumbler disc of the lock to a position that differs from the lock-model-specific standard rotation angles.