EP0571311A1

EP0571311A1 - Cylinder lock with magnetic pin tumblers

Info

Publication number: EP0571311A1
Application number: EP93500039A
Authority: EP
Inventors: Jacinto Azkarate Basabe
Original assignee: Metalurgica Cerrajera de Mondragon SA
Current assignee: Metalurgica Cerrajera de Mondragon SA
Priority date: 1992-04-23
Filing date: 1993-04-07
Publication date: 1993-11-24

Abstract

To complement the classical set of pins and counterpins that a conventional bramah lock is provided with, the device of the invention comprises a complementary pin or cog (6) established in a housing in the fixed body (1) of the tumbler and tending to be permanently driven by a spring (7) into a housing (8) in the revolving cylinder (2), which housing is in turn provided with a permanent magnet (9) that when the tumbler is at rest allows the said complementary cog (6) to enter the said housing (8), helping to lock the said revolving cylinder (2), whereas when then relevant key (4) likewise provided with a permanent magnet (9) is inserted, this magnet causes the junction plane (12) between the cog (6) and the magnet (9) to coincide with the junction plane (13) between the fixed body (1) and the revolving cylinder (2) thereby to allow the latter to turn.

Description

OBJECT OF THE INVENTION

The present invention relates to a magnetic safety device applicable to any kind of conventional bramah locks, designed as a complement to enhance the level of safety of the lock in regard to the criminal manipulation of its tumbler using a picklock, passkey or the like.

BACKGROUND OF THE INVENTION

It is well-known that tumblers in conventional locks comprise a combination of fixed body and revolving cylinder axially housed within the former, such elements having a number of radial holes that can in turn face each other axially and wherein play a number of pins and counterpins that are fitted with springs or coils, in order for the said pins to take up a locked position simultaneously affecting the fixed body and the revolving cylinder, and hence locking the latter, whereas when the key acts on the counterpins, the latter cause the pins to be moved against the said springs until they take up a specific position in which the junction plane between pins and counterpins coincides with the junction plane between the fixed body and the revolving cylinder, or in other words the said revolving cylinder is free to revolve generally driven by the key itself and driving in that movement the cam associated to the said cylinder and which is the means driving the lock element as such.
Furthermore, the keys driving these tumblers have a fancifully serrated edge or other kind of irregular and fanciful reliefs, duly matching the specific length of all the counterpins in the tumbler to define the precise position of the latter in order for opening to take place.
With this structure it is rather easy for a criminal to make copies of keys if the original is obtained by any means, or even to picklock the actual lock tumbler in order to suitably drive the counterpins.

DESCRIPTION OF THE INVENTION

The complementary safety device subject of the invention was designed to fully solve this problem in order to on the one hand enhance the difficulty in obtaining a copy of the original key, to the extent that the latter can almost only be supplied by the lock manufacturers, and indeed rendering picklocking or otherwise manipulating of the tumbler absolutely impossible.
More specifically and in order to achieve the above, the magnetic device subject hereof, using any conventional tumbler-key assembly, is essentially characterized in that the tumbler has a complementary pin or cog that also tends to lock the revolving cylinder in the tumbler with the assistance of a spring, the pin working with a magnet provided with a sheath which in turn plays in a housing within the tumbler's revolving cylinder, the magnet being substantially shorter axially than the housing in order for the pin or cog to tend to remain in the lock position by action of the said spring.
Additionally, the cam has at least another magnet (two when the key is reversible) in order for the said magnet to face the tumbler's magnet when the key is fully inserted, the said magnets being suitably polarized in order that they tend to move out radially to a limiting position in which the revolving tumbler body is released given that the supporting plane between the pin or cog and the magnet is positioned at the junction plane between the fixed body and the tumbler's revolving cylinder, as is the case with the other pins and counterpins in the tumbler, in this coupling position of the key.

DESCRIPTION OF THE DRAWINGS

In order to provide a fuller description and contribute to the complete understanding of the characteristics of this invention, a set of drawings is attached to the specification which, while purely illustrative and not fully comprehensive, shows the following:

Figure 1.- Is a cross-section of a bramah lock equipped with the magnetic safety device subject hereof, a section taken at the level of the elements making up the said complementary safety device.
Figure 2.- Is a close-up of the key which fits in the tumbler shown in the above figure.
Figure 3.- Is a section as in figure 1, though with the tumbler having the key of figure 2 inserted therein and hence being open.
Figure 4.- Is a view similar to that of figure 1, showing a different embodiment of the invention.
Figure 5.- Is finally a view similar to that of figure 3, though again with regard to the embodiment of the above figure.

PREFERRED EMBODIMENT OF THE INVENTION

In light of these figures it is clear that the magnetic safety device subject of the invention is applicable to bramah locks of any conventional kind, such having a fixed body (1) and a revolving cylinder (2), the latter with a longitudinal housing (3) to receive the relevant key (4), which key can have recesses (5) that are fancifully shaped and distributed, located on one of the faces thereof, as shown in the embodiment of figure 2, though a key can also be used with its "key" defined by a fanciful serration on one of its edges and longitudinal grooves on its face-sides, or otherwise conventionally and appropriately.
In any event, the safety device subject hereof comprises the provision in the tumbler, in addition to the classical housings for pins and counterpins, of a complementary pin or cog (6) likewise fitted with a spring (7) housed in the radial projection of the fixed body (1) and able to face a complementary housing (8) in the revolving cylinder (2), but specifically characterized in that this housing (8) that preferably does not lead into the housing (3) of the key, is provided with a permanent magnet (9) having a sheath (10) suitably structured to expedite the sliding thereof along the walls of the said housing (8) with regard to which the permanent magnet (9) is shorter, so that the pin or cog (6) will in the absence of the key and by action of the spring (7) partially penetrate the said housing (9) or act as another lock element to prevent the cylinder (2) from turning with regard to the body (1).
The key (4) is additionally provided with a permanent magnet (11) (two if the key is reversible, for instance as in the chosen practical embodiment) so that when the said key (4) is fully inserted within the tumbler and as shown in figure 3, the said magnet (11) axially faces the housing (8) and hence the permanent magnet (9) which plays within the same, the polarity being such as to tend to move the magnet (9) away, and strong enough to overcome the spring tension (7) and move the pin or cog (6) to a position such that its junction plane (12) with the magnet (9) coincides with the annular plane (13) relating the revolving cylinder (2) to the fixed body (1), as also shown in the said figure 3, in which position the pin or cog (6) shall have left its locking position to allow the cylinder (2) to turn when the latter is driven in that direction with the actual key (4).
It can be inferred from the above that it will prove quite difficult to copy a key (4) as shown in figure 2 given that in order for the said key to be useful the same must have a magnet (11) of very specific characteristics and moreover very specifically positioned, and the tumbler is furthermore wholly inaccessible from the mechanical standpoint, with picklocks and the like, inasmuch as it is by no means possible to move the complementary pin or cog (6) other than by creating a suitable magnetic field in the working area of the permanent magnet (9), which magnetic field shall if weaker be incapable of moving the cog (6) sufficiently, and if excessive will also move the same excessively, in which case the actual sheath (10) supporting the magnet (9) will become the element that continues to hold the tumbler locked, since it will at the same time take up a position in the housings of the fixed body (1) and of the revolving cylinder (2).
In accordance with a different practical embodiment of the invention, as shown in figures 4 and 5, and in order to prevent the intensity of the magnetic fields generated by the magnets in the key and the tumbler from being very critical, the diameter of the pin (6') and hence of its housing in the fixed cylinder (1) has been provided to be substantially smaller than that of the housing (8') established in the revolving cylinder (2) and in which the permanent magnet (9) movable by the magnet (11) in the key (4) respectively moves, so that the force fields generated by such magnets (9') and (11) are such that when the key (4) is inserted in the tumbler, the permanent magnet (9') easily overcomes the spring (7) tension and tends to move radially towards a limiting position defined by a stepping (14) that is in turn defined by the various diametric dimensions of the housings for each pin, which position is shown in figure 5, where the junction plane (12) between the pin (6') and the permanent magnet (9') is positioned flush with the junction plane (13) between the fixed body (1) and the revolving cylinder (2) and in which the said cylinder (2) may turn freely for opening purposes.

Claims

1.- Magnetic safety device applicable to bramah locks, of the kind having a fixed body and a revolving cylinder housed within the former, the said elements having a number of radial housings fitted with moving lock pins and counterpins equipped with respective springs and suitably positioned in order to allow the cylinder to turn when the relevant key is inserted in the latter, essentially characterized in comprising a complementary pin or cog (6) established in a likewise complementary housing in the fixed body (1) and fitted with a spring (7) that tends to drive the same towards a respective housing (8) that preferably does not actually lead into the housing (3) in the key (4), the housing (8) being designed to be partially taken up by a permanent magnet (9) fitted with a supporting sheath (10) and particularly characterized in that the key (4), in addition to the classical serrations, recesses or any other kind of irregular and fancifully distributed patterns designed to drive the tumbler's pins and counterpins, has at least a permanent magnet (11) that faces the permanent magnet (9) in the tumbler when the said key is fully inserted, particularly characterized in that the said magnets generate opposed fields that tend to move away from each other, with a specific intensity that defines a suitable movement of the cog (6) -magnet (9) assembly against the spring (7) in order for the junction plane (12) between the cog (6) and the magnet (9) to coincide with the junction plane (13) between the fixed body (1) and the revolving cylinder (2), thereby allowing the latter to turn.

2.- Magnetic safety device applicable to bramah locks, as in claim 1, characterized in that the blind housing or hole in the fixed body (1) and contemporaneously the complementary pin or cog (6') moving therein are smaller in diameter than the housing (8') and the permanent magnet (9') established in revolving cylinder (2) in order for a stepping (14) to be established between both housings to act as an abutment limiting the radial displacement of the mobile magnet (9') when the relevant key (4) is inserted in the tumbler.