ES2823679T3 - Security device for a cylinder lock - Google Patents

Abstract

Security device adapted to be coupled to a cylinder lock, said security device (1) comprising a casing (2) that can be associated with said lock and provided with a first axial opening (3) adapted to house a cylinder of said lock, said first axial opening (3) being disposed eccentrically with respect to the center of said casing (2), a protection key plate (6) adapted to engage said casing (2), said key plate (6) being protection provided with a second through opening (7) arranged eccentrically with respect to the center of said protection key plate (6) in such a way that said second through opening (7) is aligned, in use, with said first opening (3), a sliding element (16) that can move with respect to said housing (2) between a locking position, in which said sliding element (16) occludes said first opening (3) in order to prevent, in use, access to di said cylinder, and an unlocking position, in which said sliding element (16) allows access to said first opening (3), and a combinatorial unit (17, 18, 19, 20, 21, 22, 23, 24) magnetic that can move together with said sliding element (16), providing a cavity (9) oriented, in use, towards said casing (2) on an internal surface (8) of said protection key plate (6), said cavity (9) a substantially linear extension and being arranged substantially parallel to the median axis passing through said second through opening (7) and said protection key plate (6), guiding means (10, 11) being provided in each side of said cavity (9), said guide means (10, 11) comprising a first guide surface (10) arranged on one side of said cavity (9) and a second guide surface (11) arranged on the side opposite of said cavity (9), said means (10, 11) including guiding means (12, 13, 14, 15) of hitch comprising at least a first recess (12) and a second recess (13) provided on said first guiding surface (10), and at least one third recess (14) and a fourth recess (15) provided on said second surface (11) guiding, said sliding element (16) comprising locking means (25, 26) adapted to engage with said engagement means (12, 13, 14, 15) to firmly lock said sliding element (16) in said position locking or unlocking position, said locking means (25, 26) including a pair of pins (27, 28) provided with respective heads (30A, 30B) having a shape complementary to the shape of said means (12, 13 , 14, 15) of engagement, said heads (30A, 30B) being adapted to selectively engage with said first recess (12) and said third recess (14), when said sliding element (16) is in said locking position, and said second recess (13) and said fourth recess (15) when said element sliding element (16) is in said unlocking position, characterized in that said magnetic combinatorial unit (17, 18, 19, 20, 21, 22, 23, 24) includes at least four satellites (17, 18, 19, 20), specifically a first satellite (17), a second satellite (18), a third satellite (19) and a fourth satellite (20) each containing respective magnetic means (21, 22, 23, 24), said at the same time least four satellites (17, 18, 19, 20) adapted to be rotatably housed in respective seats (34, 35, 36, 37) provided on said sliding element (16), said seats being mutually arranged at right angles, in the that said first recess (12) is oriented axially towards said third recess (14) and said second recess (13) is oriented axially towards said fourth recess (15), said locking means (25, 26) being controlled by said at least four satellites (17, 18, 29, 20), in which each of said first satellite (17), second sa satellite (18), third satellite (19) and fourth satellite (20) comprise a respective cut-out (38, 39, 40, 41), said blocking means (25, 26) further comprising a first enlarged portion (29A) and a second widened portion (29B) respectively connecting said heads (30A, 30B) with respective pins (27, 28), said first widened portion (29A) being adapted to act together selectively with the respective cutouts (38, 40) of said first satellite (17) and said third satellite (19) and said second portion (29B) being widened adapted to act together selectively with the respective cutouts (39, 41) of said second satellite (18) and said fourth satellite (twenty).

Description

DESCRIPTION

Security device for a cylinder lock

Technical field of the invention

The present invention relates to an improved security device for a cylinder lock, in particular for doors or gates, which has the purpose of protecting said cylinder lock against tampering, tampering or attempted vandalism.

Background of the invention

Cylinder locks are widely known which are suitable, for example, to allow the closing and opening of a door or gate, including a cylinder that is operated by means of a relative key inserted into a keyhole arranged axially with relative to the cylinder.

Known-type cylinder locks are generally made of brass, a material that offers little mechanical resistance against forced entry attempts made by drilling and / or forcing and / or violent pulling. In order to protect the cylinder against possible forcing, a known solution is to fasten to the lock a covering element arranged to cover the cylinder and consisting of an essentially circular shaped plate fitted, in the keyhole in the cylinder, of a round hole that is rotatably connected to a keyhole protection plate provided with a recess to allow insertion of the key. Although they improve the protection of the cylinder, however such protection key plates do not prevent partial access to the cylinder through the slit in the keyhole cover plate; thus, the cylinder is still prone to possible tampering or vandalism, such as, for example, the insertion of glue or other substances into said indentation with the intention of damaging the cylinder.

Italian patent IT 1342717 B describes a security device for the cylinder of a lock comprising a strip of essentially rectangular shape having, at one end, a through opening into which the section of the cylinder that protrudes through is inserted. starting from the lock.

Two seats are formed on the front surface of the strip, facing the opposite side of the lock, within which two substantially cylindrical cams containing magnets are rotatably housed. A cutout adapted to engage with a respective locking pin slidably contained within a through hole formed transversely to the strip and communicating with the seat of the respective cam is radially formed on the side surface of each cam. Each pin is pushed out of the respective through hole by a spring inserted into the hole.

On the front surface of the strip, and therefore on the outer side of the door so that it can be accessible to the user, a covering element is slidably associated which can selectively occlude the lock cylinder.

Laterally with respect to the covering element, relative grooves are formed, one on each side, which can be engaged by the pins protruding from the strip when the covering element completely covers the cylinder; in this way, the sliding of the covering element with respect to the strip is blocked.

Release of the cover element is accomplished by placing on the same element a relative magnetic key containing magnets that can be engaged with the magnets contained in the cams to cause the cams to rotate to the point where the circumferential cutouts are brought into a position. axial alignment position with pins.

Lowering the cover element causes the pins to come out of the side slots and into the cam cutouts, to allow the cover element to slide down and make the cylinder accessible for inserting the key to open the door.

Although the security device described above provides greater protection compared to conventional keyhole protection plates, it still has some drawbacks.

To begin with, the size of the device and, in particular, its considerable vertical extension, in addition to rendering it aesthetically unattractive, can lead to seizing or jamming during the sliding of the covering element.

In addition, the positioning of the covering element outside the strip, and therefore in view on the external face of the door on which the device is mounted, makes it easily vulnerable to any act of tampering, forcing or vandalism, for example with hammer blows to forcibly lower the cover member or by drilling to access the cylinder, even if the cover member is in the locked position.

Another drawback is found in the possible difficulty in the unlocking operation under normal conditions, in which the user is required to apply, with a certain force, a downward push on the covering element to disengage the pins from the lateral grooves of the own covering element. As a partial solution to the above problems, the solution suggested in the European patent application EP 2913461 A1, on which the preamble of claim 1 is based, has been proposed, consisting of a security device for a cylinder lock that includes a cylindrical casing that can be associated with said lock and provided with an axial opening in which to house a cylinder of said lock, said opening being eccentric with respect to the center of the casing. A combinatorial unit comprises magnetic means, a sliding element interposed between the casing and a protection key plate adapted to engage the casing and provided with a second through opening arranged out of line with respect to the center of said key plate for alignment, when in use, with the axial opening. The sliding element moves between a locking position, in which it occludes the axial opening to prevent access to the cylinder, and an unlocking position in which it allows access to the opening. The change between the locked position and the unlocked position, and vice versa, can be actuated by a magnetic actuator provided with a combination designed to act in conjunction with the magnetic means of the combinatorial unit.

Although this prior art solution effectively solves the problems described above, it is limited in the number of possible combinations that can be obtained with the combinatorial unit.

Document EP 2767656 A1 discloses a lock comprising a cylinder, fixed to a door or door leaf, with which a pivot is associated in a coaxial and rotational manner, a lever for closing the door or door leaf with a jamb which is keyed to the end of the pivot; a separate body can be releasably keyed to the head of the pivot and is provided with magnetic means for temporary blocking of the rotation of the body relative to the cylinder.

Technical problem

Therefore, it would be desirable to modify and improve the prior art solution described in EP 2913461 so that the combinatorial unit can offer a very high number of possible combinations.

Summary of the invention

Therefore, the main objective of the present invention is to improve the prior art cylinder lock security device of the above-mentioned patent to considerably increase the number of combinations that can be obtained with the combinatorial unit.

In the scope of the above objective, an aim of the present invention is to provide an improved security device for a cylinder lock without considerably increasing its dimensions with respect to the prior art device of patent EP 2913461.

Another purpose of the present invention is to provide an improved security device for a cylinder lock in which the structural simplicity and the ease of use thereof are not changed, or improved, with respect to the device known from EP 2913461 .

A non-secondary purpose is to provide an improved security device for a cylinder lock which achieves the aim and purposes stated above at competitive costs and which can be obtained with the usual well-known machinery, plant and equipment.

The above object and purposes, and others that will become more apparent from the following description, are achieved by an improved security device for a cylinder lock as defined in claim 1.

Therefore, it refers to a security device adapted to be coupled to a cylinder lock, said security device comprising a housing that can be associated with said lock and provided with a first axial opening adapted to house a cylinder of said lock, said lock being first axial opening arranged eccentrically with respect to the center of said casing, a protection key plate adapted to engage said casing, said protection key plate being provided with a second through opening arranged eccentrically with respect to the center of said protection key plate such that said second through opening is aligned, in use, with said first opening, a sliding element which can move with respect to said casing between a locking position, in which said sliding element occludes said first opening in order to prevent, in use, access to said cylinder, and an unlocking position, in which said sliding element allows access to said first opening, and a magnetic combinatorial unit that can move together with said sliding element, providing a cavity oriented, in use, towards said casing on an internal surface of said protection key plate, said cavity having an extension substantially linear and being arranged substantially parallel to the median axis passing through said second through opening and said protection key plate, guiding means being provided on each side of said cavity, said guiding means comprising a first guiding surface arranged on one side of said cavity and a second guiding surface arranged on the opposite side of said cavity, i said guiding means including hooking means comprising at least a first recess and a second recess provided on said first guiding surface, and at least one third recess and a fourth recess provided on said second guiding surface, said sliding element comprising means adapted to engage with said hooking means to firmly lock said sliding element in said locking position or unlocking position, said locking means including a pair of pins provided with respective heads having a shape complementary to the shape of said means of engagement, said heads being adapted to selectively engage with said first recess and said third recess, when said sliding element is in said locking position, and said second recess and said fourth recess when said sliding element is in said unlocking position.

The device is further characterized in that said magnetic combinatorial unit includes at least four satellites, specifically a first satellite, a second satellite, a third satellite and a fourth satellite, each containing respective magnetic means, said at least four satellites being adapted to be rotatably housed in respective seats provided on said sliding element, said seats being mutually disposed at right angles, wherein said first recess is oriented axially towards said third recess and said second recess is oriented axially towards said fourth recess, said recess being controlled blocking means by means of said at least four satellites, wherein each of said first satellite, second satellite, third satellite and fourth satellite comprises a respective cut-out, said blocking means further comprising a first widened portion and a second widened portion connecting respectivam between said heads to the respective pins, said first widened portion being adapted to cooperate selectively with the respective cutouts of said first satellite and said third satellite and said second widened portion being adapted to cooperate selectively with the respective cutouts of said second satellite and said fourth satellite.

Brief description of the figures

Additional characteristics and advantages of the present invention will become more apparent from the following description of a particular, but not exclusive, embodiment, illustrated merely by way of an indicative, but not limiting example, with reference to the attached figures, in which:

figure 1 shows, in an exploded front perspective view, an improved security device for a cylinder lock according to the present invention;

figure 2 illustrates the device of figure 1 in an exploded rear perspective view;

Figure 3 illustrates the device of the previous figures in a front elevation and without covering the casing in an initial operating phase of blocking access to the lock;

figure 4 illustrates the device in the operating phase of figure 3 with a magnetic actuator applied; Figures 5 and 6 illustrate, in views similar to that of Figure 3, the device in intermediate operating phases of passage between the locked position and the unlocked position in which access to the lock is allowed;

figure 7 illustrates the device in the final operating phase of unlocking access to the lock with the magnetic actuator applied;

figure 8 illustrates, in a view similar to that of figure 3, the device in the operating phase of unlocking access to the lock after removal of the magnetic actuator;

figure 9 is a cross section of the device according to the vertical median plane of figure 7.

Detailed description of the invention

With reference to the above-mentioned figures, the reference number 1 indicates a security device for a cylinder lock according to the present invention.

The device comprises a casing 2, generally cylindrical in shape, designed to be associated with a lock and provided with a first axial opening 3 for inserting a cylinder (not shown in the attached figures). The first opening 3 is arranged in an eccentric position with respect to the center of the housing 2.

In order to protect the first opening 3 and therefore the cylinder contained therein, a keyhole protection disk 4 can be provided advantageously associated with the housing 2 in a position corresponding to the first opening 3.

The keyhole protection disc 4 is provided with a slot 5 to allow insertion of a key into the lock cylinder.

A protection key plate 6 can be attached to the housing 2 from the side opposite to the insertion direction of the cylinder so that, when in use, it is positioned at the front of the door facing outwards. The protection key plate 6 is provided with a second through opening 7 arranged eccentrically with respect to the center of the key plate 6 so that, when the device is mounted in place, it is positioned substantially aligned, preferably coaxially, with the first opening 3 of the housing 2 and, if present, with the keyhole protection disc 4.

On the inner surface 8 of the key plate 6 facing the housing 2 there is provided a cavity 9 having an essentially rectilinear extension and oriented parallel to the median axis passing through the second opening 7 and the key plate 6.

Guiding means 10, 11 are advantageously provided on each side of the cavity 9, consisting, for example, of a first guiding surface 10 on one side of the cavity 9 and of a second guiding surface 11 on the opposite side.

The guiding means 10, 11 include hooking means, the function of which will be explained better below, comprising, on one side, at least a first recess 12 and a second recess 13 and, on the opposite side, at least one third recess 14 and a fourth recess 15. The first recess 12 is arranged oriented axially towards the third recess 14, and the second recess 13 is arranged oriented axially towards the fourth recess 15.

Advantageously, the walls of the cavity 9, or the first guiding surface 10 and the second guiding surface 11, are joined close to the respective recesses 12, 13 and 14, 15 through an arc segment or inclined plane.

A sliding element 16 is slidably housed within the cavity 9 and can be moved between a locking position (Figures 3, 4), in which the sliding element 16 occludes the second opening 7 to close and prevent access to the pressure cylinder. the lock through the first opening 3 and, if present, the slot 5 in the keyhole protection disc 4, and an unlocking position (Figures 7, 8, 9), in which the sliding element 16 it frees the passage through the second opening 7 to allow the user to insert the key into the cylinder through the slit 5 and the opening 3.

A magnetic-type combinatorial unit can be housed in the body of the sliding element 16, which can therefore move together with the sliding element 16.

The combinatorial unit includes at least four satellites 17, 18, 19, 20, each containing, within suitable cavities, respective magnetic means 21, 22, 23, 24; the rotation of the satellites, actuated by a suitable magnetic actuator as will be better explained below, allows or blocks the sliding of the slider 16 by means of suitable locking means 25, 26 controlled by the satellites 17, 18, 19, 20. In the travel limit positions of the sliding element 16, that is, when the sliding element 16 is in the upper, or locking position, near the second opening 7 or in the lower, or unlocking position, the means 25, Locking 26 engage with the engaging means, comprising the recesses 12, 13 and 14, 15, to stably lock the slider 16 in those positions.

A first cutout 38, a second cutout 39, a third cutout 40 and a fourth cutout 41 respectively are provided on the circumference of each satellite 17, 18, 19, 20.

The locking means 25, 26 include a pair of pins 27, 28 provided with respective heads 30A, 30B having shapes, preferably hemispherical, that are complementary to the shape of the recesses 12, 13, 14, 15 so that the heads 30A, 30B can be selectively engaged with recesses 12 and 14 or recesses 13 and 15, depending on the operating position of the device. Furthermore, the pins 27, 28 have respective widened connecting portions 29A, 29B between the heads 30A, 30B and the shanks of the pins 27, 28; the widened portion 29A of the pin 27 is suitable to co-operate with the first and third cutouts 38, 40, while the widened portion 29B of the pin 28 is designed to co-operate with the second and fourth cutouts 39, 41 according to the modes of operation which will be better explained below. The pins 27, 28 are slidably housed in a through hole 31 or in respective coaxial and opposite blind holes formed transversely to slide member 16 so that said pins 27, 28 are disposed axially opposite to each other and oriented with their heads oriented in opposite directions.

Pins 27, 28 slide against deflection of elastic means, such as a respective first spring 32 and second spring 33 arranged coaxially with pins 27, 28 and in contact with suitable latching means formed in the hole 31, or a single spring deflecting against the heads of pins 27, 28.

The sliding element 16 is provided with a first seat 34, a second seat 35, a third seat 36 and a fourth seat 37 of essentially circular shape and reciprocally arranged two by two along parallel axes to essentially form a square or a rectangle. The seats 34, 35, 36, 37 are suitable to respectively house, in a rotary manner, the first, second, third and fourth satellites 17, 18, 19, 20 provided with the magnetic means 21, 22, 23, 24 first, second, third and fourth respectively. The pairs formed, respectively, by the first seat 34 and the second seat 35 and by the third seat 36 and the fourth seat 37, and consequently the satellites 17, 18, 19, 20 housed in the respective seats, are arranged axially aligned with respect to each other along an axis parallel to the axis defined by the through hole 31 and on opposite sides with respect to the through hole 31.

The first, second, third and fourth magnetic means 21, 22, 23, 24 inserted in the respective first, second, third and fourth satellites 17, 18, 19, 20 each comprise a pair of magnets with opposite S-N polarity. Four washers 42, 43, 44, 45 are advantageously provided to hold and cover the respective satellites 17, 18, 19, 20 in the respective seats 34, 35, 36, 37.

The displacement of the sliding element 16 from the locked position to the unlocked position, and vice versa, is achieved by means of a magnetic actuator 47, known, for example, from patent EP 2913461, provided with additional magnetic means arranged according to an appropriate and suitable combination to interact with the first, second, third and fourth magnetic means 21, 22, 23, 24 respectively contained in the first, second, third and fourth satellites 17, 18, 19, 20 to cause the rotation of these latter, as will be better explained below.

Advantageously, the sliding element 16 has a concavity 46 to avoid interference, in the unlocking position shown in figure 8, with the second opening 7.

The operation of the device is as follows: in the condition with the door closed with the safety device activated, and therefore with the sliding element 16 covering the second opening 7 from the inside to prevent access to the lock (figures 3 , 4), the first spring 32 axially biases the head 30A of the first pin 27 to engage with the first recess 12, while the second spring 33 axially biases the head 30B of the second pin 28 to engage with the third recess 14 along of the same axis defined by hole 31.

The satellites 17, 18, 19, 20 are arranged so that a circumferential portion of each engages with the widened portions 29A, 29B of the pins 27 and 28, in particular the first and third satellites 17, 19 engage with the widened portion 29A of the first pin 27, and the second and fourth satellites 18, 20 engage, from an opposite side, with the widened portion 29B of the second pin 28, thereby blocking the sliding of the pins 27, 28 to along the hole 31 to prevent disengagement of the heads 30A, 30B from the recesses 12, 14.

The magnetic means 21, 22, 23, 24 are reciprocally arranged in a random manner depending on the position imposed thereon by the last operation to unlock the magnetic actuator 47 to bring the device to the closed position.

In the position described above, the movement of the sliding element 16 is blocked by the engagement of the heads 30A, 30B in the respective recesses 12, 14; the heads 30A, 30B are locked in turn by the engagement of the satellites 17, 18, 19, 20 with the enlarged portions 29A, 29B, thus preventing the sliding of the pins 27, 28. With this configuration, it is completely prevented access to the cylinder and therefore to the lock.

To obtain the unlocking of the sliding element 16, and therefore allowing access to the cylinder to insert the key, it is necessary to set the magnetic actuator 47 against the external force of the safety device in the second opening 7, internally covered by the sliding element 16 .

The specific magnetic combination previously arranged in the actuator 47 is configured to impose a movement of the magnetic means 21, 22, 23, 24 to induce a rotation in opposite directions to the satellites 17, 18, 19, 20 to bring the respective cutouts 38, 39, 40, 41 to face the widened portions 29A, 29B of the pins 27, 28.

In particular, with reference to Figure 5, the first and third satellites 17, 19 respectively achieve a clockwise and counterclockwise rotation to bring the respective cutouts 38, 40 to face the enlarged portion 29A, while the 18, 20 second and fourth satellites rotate respectively in a counter-clockwise direction and one in a clockwise direction to bring the respective cutouts 39, 41 to face the enlarged portion 29B .

In this way, the movement of the opposing pins 27, 28 is no longer blocked by the satellites 17, 18, 19, 20, and therefore said pins 27, 28 are free to slide along the hole 31 to disengage the heads. 30A, 30B from the respective recesses 12, 14. However, the free sliding of the pins 27, 28 is elastically counteracted by the springs 32, 33, which, however, push the heads 30A, 30B to engage in the respective recesses 12, 14, as shown in the figure 5.

Therefore, to disengage the heads 30A and 30B it is necessary to pull the magnetic actuator 47 downwards, keeping it always in contact with the safety device 1 in order to consequently obtain the guided downward movement of the sliding element 16, which contains the combinatorial unit. magnetic, along the walls of the cavity 9 or, if present, of the guide means 10, 11. The arc-shaped or inclined plane profile of the walls of the cavity 9, or of the guide means 10, 11 if present, makes it possible to advance the pins 27, 28 in a sliding manner along the hole. 31 to disengage the heads 30A, 30B from the recesses 12, 14, overcoming the elastic reaction of the springs 32, 33, as shown by way of example in Figure 6; in this way, the second opening 7 is gradually made accessible to make it possible, after the operation is completed, to insert the key to open the lock.

At the end of the movement of the sliding element 16, and therefore with the second opening 7 fully accessible, the heads 30A, 30B of the pins 27, 28, pushed by the action of the springs 32, 33, engage respectively with the recesses 13 , 15 seconds and a quarter; the subsequent withdrawal of the magnetic actuator 47 at the end of the movement of the sliding element 16 returns the satellites 17, 18, 19, 20 to the initial position with respective reverse rotations with respect to the previous rotations, as shown in figures 7 and 8 The rotations of the satellites 17, 18, 19, 20 lock the heads 30A, 30B of the pins 27, 28 in the respective seats 13, 15, since the enlarged portions 29A, 29B are no longer interconnected with the cutouts 38, 39, 40, 41, which are now oriented in opposite directions, but are oriented towards the circumferential portions of the satellites 17, 18, 19, 20. In this way, the sliding element 16 is locked in the unlock position of the device , since the sliding of the pins 27, 28 along the hole 31 is prevented.

To return the safety device 1 to the position of access to the second blocked opening 7, it is enough to repeat the previous operations in the opposite direction, positioning the magnetic actuator 47 in the device 1 to cause the rotation of the satellites 17, 18, 19 , 20 to disengage the heads 30A, 30B from the respective seats 13, 15 and allow upward sliding of the sliding element 16 under tension by the magnetic actuator 47.

The advantageous presence of inclined planes or arc-shaped sections connecting the recesses 12, 13, 14, 15, defined by the walls of the cavity 9 or by the guide means 10, 11, facilitates the disengagement of the heads 30A , 30B and makes it easier for the user to move the actuator 47 without exerting considerable effort.

From the above description, it is clear how the present invention achieves the initially stated purposes and advantages: indeed, an improved lock security device was designed with the ability to considerably increase the number of combinations that can be obtained with the combinatorial unit. . In fact, the increase from two to four satellites, each housing the same number of magnetic means, formed by a pair of magnets of opposite polarity, makes it possible to increase a factorial progression the number of combinations that can be obtained.

It is noted that the increase in the number of satellites also does not lead to an increase in the dimension and size of the device, which, however, remains compact and can be made to correspond to the conventional dimensions of locks. This is thanks to the particular compact configuration of the combinatorial unit, in which the satellites 17, 18, 19, 20 are housed in the sliding element 16 aligned two by two from opposite sides with respect to the locking means 25, 26 that block the movement of the sliding element 16. Therefore, the blocking means 25, 26 are interposed between the two pairs of satellites to be able to interact simultaneously with two satellites arranged perpendicular to the axis defined by the blocking means 25, 26.

The device according to the present invention also has a simple construction and is easy for the user to use.

Naturally, the present invention is susceptible to many applications, modifications or variants, without thereby departing from the scope of patent protection as defined by claim 1.

Furthermore, the materials and equipment used to implement the present invention, as well as the shapes and dimensions of the individual components, may be most appropriate for specific requirements.

Claims (1)

Security device adapted to be coupled to a cylinder lock, said security device (1) comprising a casing (2) that can be associated with said lock and provided with a first axial opening (3) adapted to house a cylinder of said lock, said first axial opening (3) being disposed eccentrically with respect to the center of said casing (2), a protection key plate (6) adapted to engage said casing (2), said key plate (6) being protection provided with a second through opening (7) arranged eccentrically with respect to the center of said protection key plate (6) in such a way that said second through opening (7) is aligned, in use, with said first opening (3), a sliding element (16) that can move with respect to said housing (2) between a locking position, in which said sliding element (16) occludes said first opening (3) in order to prevent, in use, access to di said cylinder, and an unlocking position, in which said sliding element (16) allows access to said first opening (3), and a combinatorial unit (17, 18, 19, 20, 21, 22, 23, 24) magnetic that can move together with said sliding element (16), providing a cavity (9) oriented, in use, towards said casing (2) on an internal surface (8) of said protection key plate (6), said cavity (9) a substantially linear extension and being arranged substantially parallel to the median axis passing through said second through opening (7) and said protection key plate (6), guiding means (10, 11) being provided in each side of said cavity (9), said guide means (10, 11) comprising a first guide surface (10) arranged on one side of said cavity (9) and a second guide surface (11) arranged on the side opposite of said cavity (9), said means (10, 11) including guiding means (12, 13, 14, 15) of hitch comprising at least a first recess (12) and a second recess (13) provided on said first guiding surface (10), and at least one third recess (14) and a fourth recess (15) provided on said second surface Guide (11), said sliding element (16) comprising locking means (25, 26) adapted to engage with said engagement means (12, 13, 14, 15) to firmly lock said sliding element (16) in said position locking or unlocking position, said locking means (25, 26) including a pair of pins (27, 28) provided with respective heads (30A, 30B) having a shape complementary to the shape of said means (12, 13 , 14, 15) of engagement, said heads (30A, 30B) being adapted to selectively engage with said first recess (12) and said third recess (14), when said sliding element (16) is in said locking position, and said second recess (13) and said fourth recess (15) when said element sliding element (16) is in said unlocking position, characterized in that said magnetic combinatorial unit (17, 18, 19, 20, 21, 22, 23, 24) includes at least four satellites (17, 18, 19, 20), specifically a first satellite (17), a second satellite (18), a third satellite (19) and a fourth satellite (20) each containing respective magnetic means (21, 22, 23, 24), said at the same time least four satellites (17, 18, 19, 20) adapted to be rotatably housed in respective seats (34, 35, 36, 37) provided on said sliding element (16), said seats being mutually arranged at right angles, in the that said first recess (12) is oriented axially towards said third recess (14) and said second recess (13) is oriented axially towards said fourth recess (15), said locking means (25, 26) being controlled by said at least four satellites (17, 18, 29, 20), in which each of said first satellite (17), second s satellite (18), third satellite (19) and fourth satellite (20) comprise a respective cut-out (38, 39, 40, 41), said blocking means (25, 26) further comprising a first enlarged portion (29A) and a second widened portion (29B) respectively connecting said heads (30A, 30B) with respective pins (27, 28), said first widened portion (29A) being adapted to selectively co-operate with respective cutouts (38, 40) of said first satellite (17) and said third satellite (19) and said second portion (29B) being widened adapted to act together selectively with the respective cutouts (39, 41) of said second satellite (18) and said fourth satellite (twenty). Safety device according to claim 1, wherein said sliding element (16) is adapted to be slidably housed within said cavity (9) to be able to move along said first guide surface (10) and said second surface (11) guiding between said locking position and said unlocking position. Safety device according to claim 1, in which said locking means (25, 26) are slidingly associated with said sliding element (16) and can move in opposite directions along a transverse axis of said element (16 ) sliding against deflection of elastic means, said locking means (25, 26) being arranged axially opposite with said heads (30A, 30B) facing opposite sides. Safety device according to claim 1, in which the passage between said locking position and said unlocking position, and vice versa, can be actuated by a magnetic actuator (47) provided with a combination adapted to act together with said unit (17, 18, 19, 20, 21, 22, 23, 24) magnetic combinatorial to confer a rotation to said at least four satellites (17, 18, 19, 20) that can disengage said locking means (25, 26) from said hooking means (13, 14, 15, 16) in such a way as to allow said sliding element (16) to be moved from said position of lock to said unlock position, and vice versa. Security device according to claim 4, wherein said rotation conferred on said at least four satellites (17, 18, 19, 20) by said magnetic actuator (47) causes said cutouts (38, 40) of said satellites (17, 19) first and third are oriented towards said first widened portion (29A) and said cutouts (39, 41) of said second and fourth satellites (18, 20) are oriented towards said second widened portion (29B) to allow said locking means (25, 26) slide to disengage said heads (30A, 30B) from said engagement means (12, 13, 14, 15) in such a way as to allow said sliding element (16) to be moved from said locking position to said unlocking position, and vice versa.