This invention concerns a security lock which can be used particularly on armoured doors and front doors.

The lock as per the invention is equipped with a special anti-burglary mechanism, in other words, it is able to resist even the most advanced break-in attempts using the insertion of counterfeit and appropriately modified universal keys.

More precisely, the lock as per the invention is equipped with a safety system which, in the event that it is forced with counterfeit and appropriately modified keys, intervenes with a series of auxiliary security cylinders, ejecting when the main cylinders are forced back.

In comparison to the traditional solutions, the lock as per the invention demonstrates the advantage of intervening with an auxiliary blocking device in cases where the main blocking device is forced open.

The object of this invention is inserted in the field of safety locks applicable to armoured doors, and more generally in the field of safety and anti-burglary devices.

As noted in the state of the art, armoured doors and front doors are usually equipped with safety locks that generally use keys to open, the shape of which changes based on the type of lock keyhole it is inserted in.

The locks of armoured doors must resist break-in attempts, and those equipped with a European profile cylinder lock particularly must have a protective defender on said cylinder, installed as close to the door as possible, better if cone-shaped, and the cylinder must also have anti-drill and anti-tear features.

The classic double-bit locks are among the most used in armoured front doors, and include a central deadbolt consisting of several sliding cylinders which fit into the slots created in the fixed part, allowing the blocking of the mobile part. To further increase the protection of the armoured door, vertical deadbolts are used.

The double-bit lock is also called a lever or wafer lock, with plates or gorges, or defined as "armoured" or "security lock".

The deadbolt or deadlock is moved by the key, the key is bound by the plates, bittings, levers or wafers. The height of the bittings of the key allows the grooves of the plates to align so the cam can go through said plates in order for the key to rotate and the bolt to retract.

Please note that double bit locks for armoured doors almost always have the same even and odd key turns. A "Key turn" means a 180° rotation of the key and the relative sliding of the carriage or deadlock.

Therefore with the way that locks have been conceived thus far, with the insertion of a specific key the deadbolt is pushed back allowing the door to open, since the key is a mechanical object that is inserted in the lock's mechanism thus completing it and initiating the sliding action of the deadlock by freeing the binds that were formed.

One of the most diffused techniques for forcing armoured locks is using a pry-bar or crowbar, with which you move the plates in order to insert the grooves of the plates in correspondence with the cam. This method leads to a remarkably easy implementation of the tools, using concepts and operations available to all, with the only disadvantage that the opening execution may be slow since you need to perform the entire opening manipulation for all 2 or 4 key turns; furthermore, the result of forcing it open is tied to the efficiency and speed of the execution, linked to dexterity and training.

Nevertheless, bad guys who want to force a traditional lock tend to use break-in tools that allow them to achieve the objective, and in any case a bad guy who has access to specific equipment and the time available can open any type of door with any type of lock and with any degree of security.

Some examples of well-known locks are those described in documents EP2278100, or FR2841927, or even CH677517, and they are traditional type locks which have the aforementioned drawbacks.

The purpose of this invention is to create a security lock that can withhold break-in attempts and even attempts where the main deadbolt is forced open.

In fact, in accordance with the invention, in the event that the bad guys manage to force open the main deadbolt an auxiliary safety deadbolt will intervene, which is activated by the same key that pushes back said main deadbolt.

This way the lock becomes absolutely ironclad, guaranteeing the utmost endurance of the components even against the most advanced break-in attempts.

Therefore, the lock according to the invention uses a pair of independent deadbolts, one of which consists of the main deadbolt and is used for the regular opening and closing of the door, while the other consists of an emergency auxiliary deadbolt that intervenes in cases where the main deadbolt is forcefully pushed back by a non-original key.

Further features and details of the invention may be better understood by the description below, given by way of example and not of limitation, as well as by the attached table of drawings, in which:

• figure 1 represents the overall axonometric schematic view of the lock according to the invention with the main deadbolt in the outward position;
• figure 2 is the overall schematic view of the lock according to the invention with the auxiliary deadbolt in the outward position;
• figure 3 illustrates the schematic view of the security lock according to the invention with both deadbolts pulled back and in the open door position;
• figure 4 shows the exploded schematic and axonometric view of the inner part of the key activating device;
• figure 5 represents the overall schematic frontal point of view of the lock according to the invention.

With reference to the figures attached, 10 indicates the overall lock according to the invention, which substantially consists of an armoured housing box 11, where there are mechanical parts that engage the slots created in the fixed part and that allow the blocking of the mobile part.

More precisely, inside the armoured housing box 11, there is the first horizontal sliding carriage 12 with the locking cylinders 13 fixed on its exterior, and a second carriage 14 also sliding horizontally with the auxiliary locking cylinders 15 fixed on its exterior.

The upper carriage 12 and the lower carriage 14 are arranged respectively above and below the central control cylinder 16 which includes the parts determining the horizontal movement of the two carriages.

In fact, both the upper carriage 12 and the lower carriage 4 have serrated edges, indicated respectively with 17 and 18, on which the serrated gears 19 and 20 operate, forming part of the central control unit 16.

The upper carriage 12 has a counter-force spring 21 that keeps it in an outward pushed position.

As seen in figure 4, the control unit 16 substantially consists of a central plug 22 which includes said first serrated gear 19, and on this central plug 22 there is a second coaxial plug 23 attached that bears a second serrated gear 24, which faces gear 19.

The central plug 22 is inserted in a blocking unit 25 attached to a bracket 26, upon which the carriages 12 and 14 slide horizontally.

The central plug 22 along with the respective gear 19 operates on the main carriage 12, while the coaxial plug 23 along with the respective gear 24 operates on the auxiliary security carriage 14.

As seen in figure 2, the main carriage 12 and the auxiliary security carriage 14 are kept in pre-established positions with the use of screws 28 and 29 which, using the thrust of the springs 30, push the respective ball bearings 31 in one of the holes 32 created on each of the carriages.

Figure 2 also illustrates the use of a sensor 33 which determines the control of any electronic blocking accessories supplied.

According to the invention, as seen in figure 4, the keys for opening and closing the lock are different; more precisely there is a key 33 with a certain bitting that opens from the outside of the residence and another key 34 with a different bitting than the previously described which opens from the inside of the residence.

Please note that in order to obtain the release of the carriage 12 in order to close the door, both from the outside as well as from the inside, you must insert one of the two keys 33 and 34 in the lock unit.

From an operational point of view the lock device described allows, through the regular insertion of a key, for the central plug 22 to determine the rotation of the gear 19 thus sliding the carriage 12, which determines the insertion or extraction of the cylinders 13 in the holes of the fixed structure.

In the event of an attempt to force the lock, for example through the use of counterfeit keys, plug 22 binds to plug 23 and it is in this situation that the upper carriage 12 is pushed back while the lower carriage 14 moves forward thus blocking itself in the hole of the fixed part, preventing the door from opening.

The invention was previously described with reference to one of its preferential embodiments, but it is clearly susceptible to numerous variations which fall within its scope in the framework of technical equivalents.