DESCRIPTION

The present invention relates to a lock, in particular for a door or the like (e.g. a main entrance door, a reinforced door, etc.), according to the preamble of claim 1. Locks commonly known as "cylinder" locks are known in the art which comprise:

- a peripheral cylinder comprising a longitudinal cavity;

- an internal cylinder housed in said longitudinal cavity and provided with a longitudinal recess for inserting a key having at least one shaped profile, wherein said peripheral cylinder and internal cylinder comprise, respectively, a plurality of channels arranged radially and substantially aligned with and facing towards each other when the lock is in a locked configuration, said channels being adapted to slideably receive retaining means (usually comprising pins associated with respective counter-pins and respective elastic means) for preventing the internal cylinder from turning in the peripheral cylinder when the key is not housed in said longitudinal recess.

As a consequence, in the locks of the type described above, when the key is inserted into the longitudinal recess, it acts upon said pins, due to its shaped profile, in such a way as to bring the discontinuous section that separates a pin from a respective counter-pin into a condition of perfect alignment with the discontinuous surface between the internal cylinder and the peripheral cylinder, which are thus disengaged from each other. In this condition, by turning the key head protruding from the lock it is possible to rotate the internal cylinder within the peripheral cylinder in order to unlock the lock.

In the art, the internal cylinder is also defined as "rotor", since it is moved by the rotation of the key head, whereas the peripheral cylinder is also defined as "stator", since is it the fixed part of the lock.

However, the locks known in the art and described above suffer from a few drawbacks.

In fact, said locks are structurally fragile and can be easily broken by means of tools (e.g. pipes or levers of various kinds) acting, in particular, upon the internal cylinder or rotor. Furthermore, all such locks have, without distinction, a front slot for inserting a key, which may have slightly different shapes and profiles; this implies a natural predisposition of such locks to the insertion of a tensioning tool, a picklock or other tools allowing the exertion of strong levers that may be deleterious for the locks themselves.

A very effective effraction technique has been recently conceived (called "key- bumping"), which is based on the possibility for the burglar to take possession of an uncoded key substantially of the same type as the one associated with a given cylinder-type lock. After having shaped said key in such a way as to create an even number of grooves in succession, the depth of which is equal to or greater than the maximum depth of the grooves in the original key (associated with the lock of interest) in order to obtain a "generic" key, the effraction consists of inserting said "generic" key into the cylinder, twisting it, and rhythmically hitting its protruding head with a heavy tool (e.g. a hammer). The percussion of the mass on the head of the key results in a small and very fast forward movement of the key in the cylinder, resulting in an impulsive collision of the inclined surface of each one of the grooves of the "generic" key against the head of the respective pin of the cylinder; following this collision, each pin will transfer the accumulated energy to the respective counter-pin (since the pin and the counter-pin rest on each other), which will then be thrown towards the end of the channel of the peripheral cylinder, thus compressing the elastic element associated therewith. After a number of successive percussions, all counter-pins will come to be, at a certain instant, in the respective channel of the peripheral cylinder; at that very instant, the internal cylinder and the peripheral cylinder will be mutually disengaged (i.e. the internal cylinder will be allowed to turn within the peripheral cylinder), and the torque applied to the key head will allow the lock to be unlocked.

As a consequence, the locks known in the art suffer from the drawback that they are not realized to adequately resist to the above-described effraction technique known as "key-bumping"; it must be pointed out that this technique is even more detrimental in that it leaves no signs of effraction indicating that the lock has been tampered with.

In this frame, it is the main object of the present invention to provide a lock realized in a manner such as to overcome the drawbacks of prior-art solutions. In particular, it is the main object of the present invention to provide a lock which is so realized as to avoid that an action on the internal cylinder, possibly exerted by means of suitable tools (e.g. pipes or levers of various kinds) might cause the lock to break and become unlocked.

It is another object of the present invention to provide a lock which is realized in a manner such as to have no front groove for inserting a key, and such as to not allow the insertion of a tool allowing the application of strong levers that might be detrimental for the lock itself.

It is a further object of the present invention to provide a lock which is realized in a manner such as to ensure a high degree of security, in particular to adequately resist to various lock effraction techniques while at the same time ensuring a reliable operation and a long life of the lock.

Further objects, features and advantages of the present invention will become apparent from the following detailed description and from the annexed drawings, which are supplied by way of non-limiting explanatory example, wherein:

- Fig. 1 is a perspective view of a lock incorporating the features of the present invention;

- Fig. 2 is a partially sectional perspective view (along line F-F of Fig. 1) of the lock of Fig. 1;

- Fig. 3 is a sectional side view of the lock along line F-F of Fig. 1;

- Fig. 4 is an exploded sectional side view of an alternative embodiment of a lock according to the present invention.

Referring now to Figures 1 to 3, reference numeral 1 designates as a whole a lock according to the present invention.

The lock 1 comprises:

- a peripheral cylinder 10 comprising a longitudinal cavity 10A;

- an internal cylinder 20 at least partially housed in said longitudinal cavity 10A, said internal cylinder 20 being provided with a longitudinal recess 20 A for inserting a key 2.

The peripheral cylinder 10 comprises a plurality of first channels 11 arranged radially and substantially aligned with respective second channels 21 of the internal cylinder 20 when the lock 1 is in a locked configuration; furthermore, said first channels 11 and second channels 21 are adapted to slideably house retaining means (designated as a whole by reference numeral 30 in Figures 2 and 3) adapted to exert a retaining action between the internal cylinder 20 and the peripheral cylinder 10 when the key 2 is not housed in said longitudinal recess 20A (i.e. as shown in Fig. 3).

Said retaining means 30 comprise pins 31 associated with respective counter-pins

32 and with elastic means 33 (e.g. coil springs, as shown in Figures 2 and 3). It should be noted that said elastic means 33 are preferably housed in the first channels 11 of the peripheral cylinder 10 and are adapted to exert a thrust on the pins 31 and counter-pins 32 towards said longitudinal recess 20A; in particular, said elastic means 33 are calibrated in a rigid manner (i.e. calibrated for an axial load greater than prior-art solutions), and in such a way as to make the currently known effraction techniques ineffective (in particular those known as "key- bumping" and "pick-gun") without incurring in seizures or excessive dynamic hardness due to friction of the same pins 31 and counter-pins 32.

In a preferred embodiment, said retaining means 30 comprise a plurality of balls 34 associated with the pins 31 and positioned in proximity to the ends of the second channels 21 that lead into the longitudinal recess 20A; in particular, said balls 34 may have a diameter of approximately 5 mm or 6 mm. The peculiar provision of the balls 34 according to the present invention proves to be particularly effective because it allows the greater axial load of the elastic means

33 to be damped by the rotation of each ball 34 during the insertion of the key 2; as a result, the greater axial load of the elastic means 33 according to the present invention is spread or divided over a larger surface, so as to avoid any dangerous jamming, excessive hardness encountered when inserting the key 2, premature wear of contacting parts, etc. Moreover, the provision of the balls 34 allows to avoid providing precious information about the path and shape of the longitudinal recess 20A, about the conformation of the key 2, and about any particular shapes of invisible components of the lock 1; as a result, the provision of the balls 34 is useful to avoid providing important information about a plurality of things that may be very significant and important for a burglar.

In addition, said retaining means 30 may also comprise a plurality of second balls 35 (shown in Fig. 3) arranged between the pins 31 and the counter-pins 32; in particular, said second balls 35 are housed in a seat formed in that portion of the counter-pin 32 which faces towards the pin 31. Also, they preferably have a diameter smaller than 5 mm, in particular a diameter of approximately 2 mm. The provision of the second balls 35 turns out to be particularly effective in those cases wherein the elastic means 33 are calibrated for a very high load, in that said second balls 35 allow the counter-pin 32 to be kept essentially suspended, with a gap of approx. 0.5-0.7 mm from the pin 31, thus drastically reducing the friction surface between the pin 31 and the counter-pin 32 (which would otherwise remain directly in contact with each other, especially if they have a flat surface, if a second ball 25 were not interposed in between), as well as the sliding resistance due to the greater pressure exerted by the radial elastic means 33 on the longitudinal recess 20A.

In accordance with the present invention, the internal cylinder 20 is fixedly mounted in the lock 1, and the peripheral cylinder 10 is mounted in said lock 1 in such a way that it can be rotated about at least a portion of the internal cylinder 20 following the insertion of the key 2 into the longitudinal recess 20A of the internal cylinder 20 and following the release of the retaining means 30.

As a consequence, in the lock 1 according to the present invention, when the key 2 is inserted into the longitudinal recess 20A, it acts upon said pins 31, due to its shaped profile, in such a way as to bring a discontinuous section that separates each pin 31 from a respective counter-pin 32 into a condition of alignment with a discontinuous surface between the internal cylinder 20 and the peripheral cylinder 10, which are thus disengaged from each other. In this condition, by turning or rotating the key head 2C (i.e. that part of the key 2 which protrudes from the lock 1), the peripheral cylinder 10 can be made to rotate about the internal cylinder 20 in order to unlock the lock 1.

As can be seen, in particular, in Fig. 3, the lock 1 comprises a cap 12 associated with said peripheral cylinder 10, said cap 12 being provided with an opening 12A substantially aligned with the longitudinal recess 20 A of the internal cylinder 20, so as to receive an end 2A of the key 2 when said key 2 is housed in the longitudinal recess 20A and allow the cap 12 and the peripheral cylinder 10 to rotate following a twisting movement of said key 2. It is therefore clear that the end 2A of the key 2 and the opening 12A of the cap 12 have complementary shapes; e.g. they may be shaped like a slit, a buttonhole, a star, a polygon, and so on.

It should be noted that said key 2 comprises an end 2A, a body 2B prevalently extending in the longitudinal direction, and a head 2C associated with the body 2B on a side opposite to the end 2A; the body 2B is shaped substantially like a bar and comprises a plurality of grooves 2B' alternating with a plurality of rises 2B", in particular said grooves 2B' matching the number of first channels 11 and being so realized as to face towards said first channels 11 (through interposition of the pins 31 and/ or the balls 34) when the key 2 is fully inserted in the longitudinal recess 20A.

Preferably, said cap 12 is associated (possibly via suitable intermediate means, not shown in the drawings) with a turn (not shown) of the lock 1; as a consequence, by rotating the peripheral cylinder 10 and the cap 12 it is possible to open or close a door (or a similar device, such as a main entrance door, a reinforced door, etc.).

On the contrary, if the retaining means 30 are not released, the peripheral cylinder 10 remains constrained to the internal cylinder 20, and it is not be possible to move the assembly made up of the peripheral cylinder 10 and the cap 12 in order to operate the turn of the lock 1.

As can be observed in Fig. 3, the part of the cap 12 that includes the opening 12A extends in a manner substantially perpendicular to an axis A-A of the longitudinal recess 20A of the internal cylinder 20. Note also that in Fig. 3, the cap 12 and the peripheral cylinder 10 are shown as distinct components made integral with each other by suitable fastening means, e.g. which can be inserted into at least one hole 12B of the cap 12 and/ or of the peripheral cylinder 10; it is however clear that the cap 12 and the peripheral cylinder 10 may also be made as one piece.

The peculiar provisions of the present invention, in particular the fact that the internal cylinder 20 is fixedly mounted in the lock 1 and the peripheral cylinder 10 is mounted in such a way that it can rotate about at least a portion of the internal cylinder 20, allow providing an anti-burglary lock 1, i.e. a lock so realized as to avoid that an action exerted on the internal cylinder 20 might cause the lock 1 to break and become unlocked.

Moreover, such provisions allow making any levers applied to the internal cylinder 20 totally ineffective, which might otherwise (on a traditionally shaped lock) be deleterious.

In particular, the internal cylinder 20 according to the present invention has been so conceived as to stay firmly secured and constrained to the remaining structure of the lock 1, thus eluding all classic fraudulent unlocking attempts, even when the latter are made by using the typical tools known in the art (e.g. levers, tensioning tools, picklocks, etc.).

It must be pointed out that the provisions of the present invention are such as to make the operation of the anti-burglary lock 1 essentially opposite to that of prior-art locks, since in the lock 1 according to the present invention the internal cylinder 10 is fixed and the peripheral cylinder 20 can turn, whereas in prior-art locks it is exactly the opposite (i.e. the peripheral cylinder is fixed and the internal cylinder can turn).

Therefore, the provisions of the present invention allow providing a lock 1 which is so realized as to ensure a high degree of security, while at the same time also ensuring a reliable operation and a long life.

In a preferred embodiment, the peripheral cylinder 10 is so realized as to comprise an annular wall 10B adapted to contain the retaining means 30 inside the first channels 11 and the second channels 21. In the annexed drawings, the peripheral cylinder 10 and the annular wall 10B are shown as separate components (in order to facilitate the positioning of the retaining means 30 into the first channels 11 and second channels 21) and are made integral with each other, in particular said annular wall 10B being press-fitted in cold conditions into said peripheral cylinder 10. It is however clear that the peripheral cylinder 10 and the annular wall 10B may also be made as one piece, in particular said annular wall 10B essentially forming the outer wall of the peripheral cylinder 10. Furthermore, the lock 1 comprises a containment cylinder 22 adapted to house at least partially the peripheral cylinder 10 and the internal cylinder 20, said internal cylinder 20 and containment cylinder 22 being fixed to each other by means of at least one coupling element 22A; for example, said at least one coupling element 22A may consist of a dowel pin (having a substantially cylindrical shape) inserted in at least one first press-fitting hole 20F formed in the internal cylinder 20 and in at least one second press-fitting hole 22F formed in the containment cylinder 22. Preferably, the internal cylinder 20 is so realized as to have a substantially T- shaped body in a sectional view (as shown in Figures 3 and 4, wherein the internal cylinder is viewed in an operating condition and the sectional view thereof shows a shape substantially resembling a "dropped T"), i.e. so as to comprise:

- a first portion 20' extending longitudinally in such a way as to comprise said longitudinal recess 20A (i.e. said first part 20' extends substantially in the same direction around the longitudinal recess 20 A);

- a second portion 20"extending substantially perpendicular to said first portion 20'.

In this embodiment, said at least one first press-fitting hole 20F adapted to receive said at least one coupling element 22A is formed in the second portion 20" of the internal cylinder 20.

Fixing the internal cylinder 20 to the containment cylinder 22 (as described above) is a preferred solution for making the lock 1 according to the present invention; it is in fact clear that the internal cylinder 20 according to the present invention may also be fixed to other elements of the lock 1, since a fundamental concept of the present invention is that the internal cylinder 20 is fixedly mounted in the lock 1 and the peripheral cylinder 10 is mounted in a manner such that it can rotate about at least a portion of the internal cylinder 20. When the internal cylinder 20 has a substantially T-shaped body (as previously described), said at least a portion of the internal cylinder 20 about which the peripheral cylinder 10 can turn corresponds to the first portion 20'.

In a preferred embodiment, the lock 1 comprises a protection bell 23 comprising a first sector 23A adapted to house at least partially the containment cylinder 22; also, said protection bell 23 comprises a second sector 23B having a substantially truncated-cone shape (in a sectional side view), so that the outer surface of said second sector 23B cannot be gripped by the tools typically employed for effraction purposes.

Said protection bell 23 has the second sector 23B facing towards an outer side of the lock 1, when the latter is in the operating condition (i.e. when the lock 1 is installed in a door or the like).

The containment cylinder 22 and the protection bell 23 are preferably made of steel, in particular an anti-drill, heat-treated, high-tensile steel.

The second sector 23B of the protection bell 23 (and possibly also the containment cylinder 22, when it extends - as shown by way of example in Fig. 3 - into the space between the protection bell 23 and the internal cylinder 20), comprises an inlet hole 23F substantially aligned with the longitudinal recess 20A of the internal cylinder 20, so as to allow inserting the key 2 into said longitudinal recess 20A.

In a preferred embodiment, the longitudinal recess 20 A is so realized as to have a substantially cylindrical shape and a substantially constant diameter (in particular, in a view along the axis A-A of said longitudinal recess 20A), in particular said diameter being approx. 6 mm; preferably, the inlet hole 23A of the protection bell 23 has substantially the same dimensions as said longitudinal recess 20 A.

Thanks to the conformation and the particularly small dimensions of the longitudinal recess 20A (and also of the inlet hole 23A of the protection bell 23), the room available to a burglar for using burglary tools is considerably reduced, thus significantly contributing to ensuring a high degree of security of the lock 1. Note also that said room available to a burglar is further reduced by the presence of the balls 34, which further limit the possibility of using burglary tools.

Preferably, said first channels 11 and second channels 21 are arranged in a substantially radial manner relative to the longitudinal recess 20A of the internal cylinder 20, in particular according to a perpendicular sectional view of said internal cylinder 20 and peripheral cylinder relative to an axis A-A of the longitudinal recess 20A; in addition, the ends of the second channels 21 positioned in proximity to the longitudinal recess 20A are tapered, so as to narrow the cross-section of said second channel 21 (and prevent the balls 34 from coming out of said second channel 21 and fully entering into the longitudinal recess 20 A).

In a preferred embodiment, the lock 1 comprises three pairs of first channels 11 and second channels 21 in a perpendicular section of the peripheral cylinder 10 and of the internal cylinder 20 relative to the axis A-A of the longitudinal recess 20A, said pairs of first channels 11 and second channels 21 being positioned substantially at 120° from each other; in substance, in a perpendicular sectional view of the cylinders 10, 20 relative to the axis A-A of the longitudinal recess 20A, each pair formed by a first channel 11 and a second channel 21 is positioned at 120° relative to another pair formed by a first channel 11 and a second channel 21. Furthermore, the lock 1 according to the present invention may be so realized that the pairs of first channel 11 and second channels 21 of a section perpendicular to the axis A-A are arranged linearly with respect to the pairs of first channels 11 and second channels 21 of a contiguous section, i.e. in such a way that the first channels 11 and the second channels 21 lie in the same longitudinal plane (i.e. a plane developing in the same direction as the axis A-A of the longitudinal recess 20A) or in the same row.

As an alternative, the lock 1 according to the present invention may be so realized that the pairs of first channels 11 and second channels 21 of a section perpendicular to the axis A-A are (angularly) offset relative to the pairs of first channels 11 and second channels 21 of a contiguous section, e.g. in such a way as to form a sort of spiral in a perspective view from the axis A-A of the longitudinal recess 20A. According to a variant of this embodiment, the lock 1 may be so realized that the pairs of first channels 11 and second channels 21 of a section perpendicular to the axis A-A are offset in a random (disorderly) manner relative to the pairs of first channels 11 and second channels 21 of a contiguous section. As a further example, the pairs of first channels 11 and second channels 21 may be offset by a few angular degrees for the purpose of making the lock 1 even more compact by reducing the thickness thereof and eliminating the need for an interspace between one section of first channel 11 and second channels 21 perpendicular to the axis A-A and the next; this structural compaction can be brought to an extreme recess limit equal to almost half the diameter of the adjacent first channels 11 and second channels 21 that precede and follow, in the longitudinal direction relative to the axis A-A.

The peculiar sunburst arrangement of three pairs, substantially equally spaced by 120°, of first channels 11 and second channels 21 allows positioning the balls 24 in such a way as to further reduce (to approx. 2.5 mm) the clearance of the longitudinal recess 20A; it is apparent that this further reduces the room available to a burglar for using burglary tools, thus further increasing the degree of security offered by the lock 1 according to the present invention.

In Fig. 3 it can also be seen that at least one counter-pin 32 of the lock 1 is associated with at least one actuation element 36 for activating a security system (designated by way of example by reference numeral 40 in said Fig. 3).

In particular, said security system 40 may be a of a programmable type (in particular comprising a control system associated with a timer) and may be associated with:

- a blocking system (not shown), in particular of a type which can be activated for a time that can be set by the user in a timer of the security system 40 in order to block the lock 1 in the event that said security system 40 detects an attempt to force the retaining means 30 of the lock 1, and/ or

- an alarm system (not shown), which is adapted to send (also via the Internet and/ or a telephone line) communications about a burglary attempt detected by the security system 40.

Fig. 4 is an exploded sectional side view of an alternative embodiment of the lock 1 according to the present invention; note that in Fig. 4 the same reference numerals have been used as those included in Figures 1 to 3 in order to designate equivalent items.

In this embodiment, the lock 1 is realized on the basis of the same concepts as those of the embodiment shown in Figures 2 and 3, since also the lock 1 comprises an internal cylinder 20 fixedly mounted in the lock 1 and a peripheral cylinder 10 mounted in said lock 1 in a manner such as to rotate about at least one portion (in particular, a first portion 20') of the internal cylinder 20 upon insertion of the key 2 into the longitudinal recess 20A of the internal cylinder 20 and upon release of the retaining means 30.

In the embodiment shown in Fig. 4, the lock 1 is suitable for use in a lock of the type known as "European cylinder", and the peripheral cylinder 10 is so realized as to comprise an appendix 13.

In particular, said appendix 13 is so realized as to have, in a sectional view perpendicular to the axis A-A of the lock 1, a smaller diameter than the main body (i.e. that part of the peripheral cylinder which receives the internal cylinder 20) of the peripheral cylinder 10. In the embodiment shown in Fig. 4, the containment cylinder 22 is so realized as to comprise a seat 22B adapted to receive said appendix 13; as a result, in the embodiment shown in Fig. 4 it can be noticed that the containment cylinder 22 has the classic conformation of a "European cylinder" lock, so that it is possible to replace prior-art locks of the "European cylinder" type with a lock 1 realized in accordance with the teachings of the present invention.

Preferably, in an operating condition the appendix 13 and/ or the seat 22B face towards an outer side of the door (or the like).

The lock 1 comprises also a clutch assembly (designated as a whole by reference numeral 50 in Fig. 4), which is associated with the appendix 13 in such a way as to allow blocking the appendix 13 and the peripheral cylinder 10 in the event that (in particular during a burglary attempt) a force is applied to the lock 1 which is greater than the force necessary for unlocking said lock 1.

Said clutch assembly 50 comprises:

- a disk 51 comprising a through hole 51 A for inserting the key 2 and at least one pair of spherical seats 51B formed on a side of said disk 51 facing towards the appendix 13;

- at least one pair of clutch balls 52 partially inserted in said spherical seats 51B;

- resistance springs 53 positioned in contact with said clutch balls 52 and with the appendix 13.

In particular, the resistance springs 53 are so calibrated as to ensure the transmission of the rotary motion of the appendix 13 and of the peripheral cylinder 10 when a suitable key 2 is inserted into the longitudinal recess 20A. Therefore, the clutch assembly 50 is so realized that the transmission of the rotary motion between the appendix 13 and the disk 51 only occurs through the clutch balls 52; as a consequence, the calibration of the resistance springs 53 will be sufficient to ensure adequate transmission of the rotary motion with the correct key 2 inserted, but, if the effort increases (e.g. because one is using an incorrect key, or under pressure exerted by tensioning tools and various attempts to turn the appendix 13), the resistance springs 53 will yield and the clutch disks 52 will prevent the appendix 13 from rotating.

The method of operation of the lock 1 according to the present invention is apparent from the above description, said lock 1 comprising: - a peripheral cylinder 10 comprising a longitudinal cavity 10A;

- an internal cylinder 20 at least partially housed in said longitudinal cavity 10A, said internal cylinder 20 being provided with a longitudinal recess 20A for inserting a key 2,

wherein the peripheral cylinder 10 comprises a plurality of first channels 11 arranged radially and substantially aligned with respective second channels 21 of the internal cylinder 20 when the lock 1 is in a locked configuration, said first channels 11 and second channels 21 being adapted to slideably house retaining means 30 adapted to exert a retaining action between the internal cylinder 20 and the peripheral cylinder 10 when the key 2 is not housed in said longitudinal recess 20A.

In accordance with the present invention, said method of operation comprises the steps of:

a) inserting said key 2 into the longitudinal recess 20A in such a way as to release said retaining means 30 and to couple an end 2A of the key 2 to an opening 12A of a cap 12 associated with said peripheral cylinder 10;

b) applying a torque to said key 2, in particular by moving a head 2C of said key, in order to turn (rotate) the peripheral cylinder 10 associated with the cap 12, in particular through a rotation of the peripheral cylinder 10 about at least a portion of the internal cylinder 20.

In particular, said step a) is carried out by means of the contact between a series of grooves 2B' alternating with a plurality of rises 2B"of a body 2B of the key 2 and respective balls 34 of said retaining means 30, so that the contact between said grooves 2B' and said balls 34 will allow damping a high axial load exerted by elastic means 33 on a plurality of pins 31 and counter-pins 33 associated with said balls 34 and positioned in said first channels 11 and second channels 21. The features of the present invention, as well as the advantages thereof, are apparent from the above description.

In particular, the fact that the internal cylinder 20 is fixedly mounted in the lock 1 and the peripheral cylinder 10 is mounted in such a way that it can rotate about at least a portion of the internal cylinder 20 allows providing a lock 1 which is so realized as to avoid that an action exerted on the internal cylinder 20 might cause the lock 1 to break. In fact, the internal cylinder 20 according to the present invention has been devised in a way which is the opposite of the solutions known in the art, since the internal cylinder 20 according to the present invention is so realized as to stay firmly secured and constrained to the remaining structure of the lock 1, thus eluding all classical fraudulent unlocking attempts, even when the latter are made by using the typical tools known in the art (e.g. levers, tensioning tools, picklocks, etc.).

Therefore, the provisions of the present invention allow providing a lock 1 which is so realized as to ensure a high degree of security, while at the same time also ensuring a reliable operation and a long life.

Thanks to the conformation and the particularly small dimensions of the longitudinal recess 20A (and also of the inlet hole 23A of the protection bell 23), the room available to a burglar for using burglary tools is considerably reduced, thus significantly contributing to ensuring a high degree of security of the lock 1. Said room available to a burglar is further reduced by the presence of the balls 34, which (in addition to damping the greater axial load of the elastic means 33, said greater load being useful for neutralizing the burglary techniques known in the art) considerably narrow the clearance of the longitudinal recess 20A, thereby further limiting the possibility of using any burglary tools. It must be pointed out, in fact, that the peculiar sunburst arrangement of three pairs, substantially equally spaced by 120°, of first channels 11 and second channels 21 is useful for positioning the balls 24 in such a way as to further reduce (to approx. 2.5 mm) the clearance of the longitudinal recess 20A, so as to further reduce the room available to a burglar for using burglary tools, thus considerably increasing the degree of security offered by the lock 1.

The fact that the lock 1 is so realized that it can be inserted into a structure of the "European cylinder" type improves the versatility of the inventive concept of the present invention, also allowing existing structures to benefit from the adoption of the lock 1 according to the teachings of the present invention.

The lock and method of operation thereof described herein by way of example may be subject to many possible variations without departing from the novelty spirit of the inventive idea; it is also clear that in the practical implementation of the invention the illustrated details may have different shapes or be replaced with other technically equivalent elements.

It can therefore be easily understood that the present invention is not limited to the above-described lock and method of operation thereof, but may be subject to many modifications, improvements or replacements of equivalent parts and elements without departing from the inventive idea, as clearly specified in the following claims.