The present invention relates to a protection device for locks that can be coupled with wood doors.

Locks are known which are adapted to allow the locked closure, and the opening, of a door and are constituted essentially by a box-like body, forming the lock, which accommodates a cylinder provided with a seat for the insertion of the stem of a key adapted to allow the activation of the cylinder and thus the unlocking of the lock, and optional means for the movement of bolts and a latch.

These cylinders of the known type are usually made of brass or in any case of materials that do not have a high mechanical strength, thus lending themselves to being easily broken-in by drilling and/or breaking and/or tearing.

In order to protect these cylinders of the known type from possible break-ins, it is common to fix, in front of the box-like body that forms the lock, in such a position as to cover the cylinder, an adapted covering element which is constituted by a boss, having a substantially circular plan shape, which has, at the keyhole of the cylinder, a circular hole within which a keyhole protection disk is rotatably associated; a slit adapted to allow the insertion of the key is provided in the disk.

The boss thus constitutes a protection for the cylinder and allows at the same time the insertion and rotation of the key in the keyhole of the cylinder.

As illustrated in Figure 1, such bosses A of the known type have however a drawback: in fact such bosses A usually have such a depth as to arrange them, with their threaded stem B, spaced from the box-like body C so that a space E remains between the bottom D of the threaded stem B and the box-like body C.

The bosses A are thus fixed to the box-like body C by means of screws F, the head G of which is arranged toward the inner side of the door H, and the stem I of which is associated with a complementarily threaded seat provided on the bottom D of the boss A.

Thus, part of the stem I of the screws F remains exposed and allows ill-intentioned individuals to break the screws by means of appropriate tools, such as pipe wrenches or the like, which are used to grip the boss and make it oscillate until the screws yield, breaking them.

The aim of the present invention is therefore to solve the highlighted technical problems, removing the drawbacks of the cited background art and thus devising a protection device which, applied to a lock provided with a covering element, allows to protect the lock from break-ins.

Within this aim, an object of the invention is to provide a device that can be applied quickly and easily also to locks of the known type.

Another object is to provide a device that is structurally simple, has modest costs and can be manufactured with known machines and systems.

This aim and these and other objects that will become better apparent hereinafter are achieved by a protection device for locks of doors, said locks comprising a box-like body, which accommodates a cylinder provided with a seat for the insertion of a key adapted to allow the activation of said cylinder, and a covering element constituted by a boss, characterized in that it is constituted by a reinforcement plate, which can be arranged in contact with said box-like body, from which a tab protrudes to which it is possible to interconnect the stem of said boss.

Further characteristics and advantages of the invention will become better apparent from the detailed description of a particular embodiment, illustrated by way of non-limiting example in the accompanying drawings, wherein:

• Figure 1 is a sectional view of background art;
• Figure 2 is a partially sectional perspective view of the device according to the present invention;
• Figure 3 is a perspective view of the device detached from the boss;
• Figure 4 is a sectional view of the device applied;
• Figure 5 is view of a detail of Figure 4;
• Figure 6 is a view, similar to the previous one, of a variation;
• Figure 7 is a view, similar to the previous one, of a variation;
• Figure 8 is a view of the variation of the preceding figure during the insertion of the boss in the device.

With reference to the figures, a protection device for locks 2 of doors 3 according to the invention is generally designated by the reference numeral 1, said locks 2 comprising a box-like body 4, which accommodates a cylinder 5 provided with a seat for the insertion of the stem of a key adapted to allow the activation of said cylinder.

The lock 2 further comprises a covering element constituted by a boss 6 comprising a head 7, of various shapes, for example conical, frustoconical, cylindrical or other, which can be positioned externally to the door 3, which has, at the keyhole of the cylinder 5, a circular hole within which a keyhole protection disk 8 is associated rotatably, a slit 9 adapted to allow the insertion of the key being provided in said disk.

An externally threaded stem 10 protrudes from the head 7; the boss 6 is fixed to the lock by means of adapted and known first screws 11.

The protection device 1 is constituted by a reinforcement plate 12, which has a plan shape that is polygonal, preferably oval or circular with an outside diameter that is greater than the outside diameter of said stem 10, and can be arranged in contact with the lateral surface 13, of the box-like body 2 that faces the boss 6.

A space 14 is formed between the lateral surface 13 and the facing terminal end 10a of the stem 10.

The reinforcement plate 12 is provided centrally with a circular hole 15, which has a diameter that is slightly larger than the outside diameter of the stem 10; a tab 16 protrudes perimetrically to said hole 15 and said stem 10 of the boss 6 can be interconnected with the tab.

The axial extension of the tab 16 is greater than the distance between the lateral surface 13 and the facing terminal end 10a of the stem 10 so as to form an end 17 that is folded advantageously at 180° toward the box-like body 4.

The end 17 is internally threaded complementarily to the stem 10 and, as shown for example in Figure 5, the stem 10 is thus rotatably associable therewith.

In this way, the boss 6 is monolithic with the door 3 and break-in resistance is increased considerably, since the stem 10 is stably fixed in position, although the space 14 exists between the lateral surface 13 and the facing terminal end 10a of the stem 10.

The first screws 11 only have the function of anchoring the boss 6.

In practice it has been found that the invention has achieved the intended aim and objects, a device having been devised which, applied to a lock, for wooden doors, provided with a covering element, allows to protect the lock effectively from break-ins.

Furthermore, the device can be applied rapidly and easily also to locks of the known type.

Finally, the device is structurally simple and has low manufacturing costs.

The materials used, as well as the dimensions that constitute the individual components of the invention, may of course be more pertinent according to the specific requirements.

Thus, as shown in Figure 6, the reinforcement plate 112 of the protection device 101 for locks 102 has, perimetrically to the hole 115, a tab 116 the end 117 of which is folded at 180° toward the box-like body 104 and is smooth, being interconnectable by mere interference with the underlying stem 110, which also is externally smooth, of the boss 106.

The locking in position of the boss 106 with respect to the door 103 occurs by means of a washer 118 which is fixed to the rear surface 119 of the stem 110 by means of second screws 120, the washer 118 protruding radially to the rear surface 119 so as to affect the folded end 117 by abutment.

Figures 7 and 8 show an additional embodiment in which the reinforcement plate 212 of the protection device 201 for locks 202 has, perimetrically to the hole 215, a tab 216 the end 217 of which is folded at 180° toward the box-like body 204 and is smooth, and so is the underlying stem 210 of the boss 206.

The locking in position of the boss 206 with respect to the door 203 occurs by means of an elastically deformable ring 221 arranged within an adapted annular seat 222 provided on the lateral surface of the stem 210 proximate to the terminal end 210a of the stem 210.

The ring 221 protrudes radially to the lateral surface of the stem 210 and affects the folded end 217 by abutment.

In order to facilitate the positioning of the stem 210, the end 217 of the tab 216 that faces the stem 210 is beveled so as to form an inclined plane 223 which facilitates, during the insertion of the boss 206 in the device 201, the temporary compression of the ring 221.

These variations, too, achieve the intended aim and objects.

The various means for performing certain different functions need not certainly coexist only in the illustrated embodiment but can be present per se in many embodiments, including ones that are not illustrated.

The characteristics of the invention indicated as advantageous, convenient or the like may also be omitted or replaced with equivalents.

The disclosures in Italian Patent Application No. 102018000005261 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.