The present invention relates to a lock with tamper-resistant elements and associated key according to the preamble of claim 1. Such a lock is known from EP 1106756 A .

Cylinder locks of the conventional type have a plurality of elements that perform a radial translational motion and enter the cylinder by way of the action of axially-acting springs, preventing the rotation of the cylinder when the appropriate key is not inserted in the lock.

The contour of the key, which is provided complementarily with respect to the length of the translational elements, allows such elements to exit from the cylinder, releasing it.

The translational elements are generally constituted by a pair of slender elements in mutual contact at one end: the element that is inserted in the cylinder when the key is removed is termed "coding pin" and the element comprised between the axially-acting spring and the coding pin is termed "driver pin".

Providing each translational element in two parts makes effraction more difficult.

An expert can in fact open a lock without using the key by using slender metallic objects, in the specific case a torque wrench and a pick.

The torque wrench is used to force the rotation of the cylinder in the opening direction: the forcing action must be strong enough to prevent the coding pins from being pushed back into the cylinder by the action of the spring after they have been made to retract, but not too strong, in order to avoid jamming the coding pins, making it impossible to retract them with an external action because of excessive friction.

The external action is applied to the coding pins by means of the pick, with which their top ends are struck, making them retract in contrast with the action of the spring.

Providing the translational elements in two parts makes effraction more difficult, since the action of the pick that causes the retraction of the coding pin is hindered by the fact that when the discontinuity surface that is present between the coding pin and the driver pin is at the boundary surface of the cylinder, it allows movement on the part of the cylinder. This movement can block the coding pin in an intermediate position that does not ensure the rotation of the cylinder and therefore ensure effraction.

The increased difficulty, however, does not ensure the safety of the lock, which could be opened without the key, albeit in a longer amount of time.

The aim of the present invention is to obviate the above-cited drawbacks and meet the mentioned requirements, by providing a lock with tamper-resistant elements and associated key that hinders opening with effraction means to a higher degree.

Within this aim, an object of the present invention is to provide a lock that is simple, relatively easy to provide in practice, safe in use, effective in operation, and has a relatively low cost.

This aim and this and other objects that will become better apparent hereinafter are achieved by the present lock with tamper-resistant elements and associated key, of the type that comprises a body, a cylindrical receptacle formed in said body, a cylinder that can rotate in said receptacle, an actuation bit that is rotationally rigidly coupled to said cylinder, a keyway for the insertion of said key, which is formed axially in said cylinder, a plurality of elements that perform a radial translational motion, each constituted by a coding pin and a driver pin, which enter said cylinder and said body and, when the key is removed, prevent the rotation of the cylinder, while by inserting the key in said keyway they are actuated into the position that enables the rotation of the cylinder, characterized in that at least one of said coding pins is constituted by a spindle provided with a substantially cylindrical head and with a shank, which is likewise substantially cylindrical and is provided with an end disk whose diameter is comprised between the diameter of the shank and the diameter of the head, said head having a larger diameter than said shank, and by a substantially cylindrical hollow pin, with an outside diameter that is approximately equal to the diameter of said head, and with a likewise cylindrical internal cavity which accomodates the shank of the spindle and whose diameter is approximately equal to the diameter of the disk and is provided with a retention groove, said hollow pin having a partially tapering tip and when the spindle protrudes partially from the cavity the axis of the spindle is allowed to tilt with respect to the axis of the hollow pin such that the disk is trapped within the groove.

Further characteristics and advantages of the present invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment of a lock with tamper-resistant elements and associated key, illustrated by way of non-limiting example in the accompanying drawings, wherein:

• Figure 1 is a front view of a lock according to the invention;
• Figure 2 is a front view of a lock according to the invention, subj ected to tampering;
• Figure 3 is a sectional side view, taken along a plane that passes through the axis of symmetry, of a coding pin of a lock according to the invention in the configuration in which its components are fully inserted;
• Figure 4 is a sectional side view, taken along a plane that passes through the axis of symmetry, of a coding pin of a lock according to the invention in an exploded configuration of its components;
• Figure 5 is a front view of a different embodiment of a lock according to the invention;
• Figure 6 is a front view of a different embodiment of a lock according to the invention, subjected to tampering;
• Figure 7 is a sectional side view, taken along a plane that passes through the axis of symmetry, of a coding pin of a different embodiment of a lock according to the invention in the configuration in which its components are fully inserted;
• Figure 8 is a sectional side view, taken along a plane that passes through the axis of symmetry, of a coding pin of a different embodiment of a lock according to the invention in an exploded configuration of its components.

With reference to the figures, the reference numeral 1 generally designates a lock with tamper-resistant elements and the reference numeral 1a designates a corresponding key.

The lock 1 comprises a body 2, a cylindrical receptacle 3 formed in the body 2, a cylinder 4 that can rotate in the receptacle 3, an actuation bit that is rigidly rotationally coupled to the cylinder 4, and a keyway 6 for the insertion of the key 1a formed axially in the cylinder 4.

A plurality of elements 7 that perform a radial translational motion are arranged longitudinally; each element is constituted by a coding pin 8 and by a driver pin 9; the elements 7 enter the cylinder 4 and the body 2 and, when the key is removed, prevent the rotation of the cylinder 4, while by inserting the key in the keyway 6 they are actuated into the position for enabling the rotation of the cylinder 4.

At least one of the coding pins 8 is constituted by a spindle 10, which is provided with a substantially cylindrical head 11 and with a shank 12, which is also substantially cylindrical and is provided with an end disk 13 whose diameter is comprised between the diameter of the shank 12 and the diameter of the head 11, the head 11 having a larger diameter than the shank 12, and by a substantially cylindrical hollow pin 14, which has an outside diameter that is approximately equal to the diameter of the head 11 of the spindle 10 and an internal cavity 15 that is likewise cylindrical and has a diameter that is approximately equal to the diameter of the disk 13 of the spindle 10 and is provided with a retention groove 16, said hollow pin 14 having a partially tapered tip 17.

The edge of the disk 13 that lies opposite the edge that is connected to the shank 12 is beveled.

In the retention groove 16, the upper boundary surface, i.e., the surface that runs from the bottom of the groove 16 to the upper region of the cavity 15, is inclined, i.e., has an upper bevel.

The coding pin 8 is installed within the body 2 and the cylinder 4 so that in the hollow pin 14 the tapering end 17 is arranged toward the keyway 6 for the key 1a and the cavity 15 is open downward. The cavity 15 accommodates the shank 12 of the spindle 10, and the head 11 of the spindle in turn rests on the upper end 18 of the driver pin 9.

The lower end 19 of the driver pin 9 rests on a spring 20 that acts axially and is arranged on the bottom of the passage 21 that accommodates the coding pin 8 and the driver pin 9. The driver pins 9 are substantially cylindrical elements provided with ends 18 and 19 that have a larger diameter in order to allow their axial offset when they are partially inserted in the body 2 and partially inserted in the cylinder 4.

The head 11 of the spindle 10 has a cambered surface that rests against the upper end 18 of the driver pin 9, providing a substantially point-like contact against the end 18.

The operation of the invention is as follows. When the coding pin 8 is in the configuration in which the shank 12 is fully contained in the cavity 15 of the hollow pin 14 (situation shown in Figure 3), the end disk 13 is arranged above and proximate to the retention groove 16.

When instead the coding pin 8 is in the configuration in which the shank 12 protrudes partially from the cavity 15 of the hollow pin 14 (situation shown in Figure 1), the end disk 13 is aligned with the retention groove 16, since the play between the shank 12 and the cavity 15 and also between the disk 13 and the groove 16 is sufficient to allow the tilting of the axis of the former with respect to the axis of the latter.

In case of effraction, the attacker acts by inserting in the receptacle 3 a torque wrench 22 and a pick 23.

By way of the impulsive action of the pick 23 (which is tapped against the tapered end 17 of the hollow pin 14), the coding pin 8 undergoes a vertical translational motion: this translational motion is not the same for all the components of the coding pin 8 (which do not move rigidly with respect to each other). The hollow pin 14 remains almost motionless, while the spindle 10 moves downward, making the driver pin 9 retract as well, said driver pin in turn acting by compressing the spring 20.

In the meantime, the torque wrench 22 keeps a moment applied to the cylinder 4 in order to jam the coding pin 8 within the passage 21 if it is made to retract completely therein following percussion applied with the pick 23.

Actually, as soon as the spindle 10 protrudes partially from the cavity 15, the torque of the torque wrench 22, due to the play between the shank 12 and the cavity 15 (and also between the disk 13 and the groove 16), tilts the axis of the spindle 10 with respect to the axis of the hollow pin and the disk 13 is trapped within the groove 16, preventing the rotation of the cylinder 4 and therefore preventing effraction.

One or more of the coding pins 9 of the lock 1 can be provided monolithically, while the others are constituted by a spindle 10 and a hollow pin 14 in order to provide low-cost, highly secure mixed solutions.

It has thus been shown that the invention achieves the proposed aim and object.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

For example, the hollow pin 14 is provided in different lengths, which correspond to the different thicknesses that the contour of the key 1a that actuates it can assume.

The embodiment shown in Figures 5, 6, 7 and 8 provides coding pins 8 that are substantially smaller than those of the solutions of Figures 1 to 4.

All the details may further be replaced with other technically equivalent ones.

In the embodiments shown, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other embodiments.

In practice, the materials used, as well as the shapes and the dimensions, may be any according to requirements without thereby abandoning the scope of the protection of the appended claims.

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.