Closure devices of the above-mentioned type are known in the art and are used particularly on bottles for holding good-quality liquors or beverages.

An example of the prior art is contained in the publication WO 96/23704.

According to the prior art described in this publication, the security ring is connected axially, by means of a plurality of small bridges, to the free edge of the stopper which is shaped like a cap and has, in its inner surface facing towards the sleeve, inside the stopper, a plurality of saw-teeth which engage between corresponding projections extending radially from the outer surface of the sleeve.

The inclination of the saw-teeth is such as to permit their insertion between the projections by screwing when the stopper is fitted on the container, but to keep them locked when the stopper is rotated in the opposite direction upon the initial opening of the container.

During this opening rotation, the axial connecting bridges are broken, resulting in the detachment of the ring from the rest of the stopper, providing evidence of the initial opening of the container.

Although the known structure mentioned above performs the function for which it is intended, it is not without serious disadvantages which include difficulty in breaking the axial connecting bridges between the security ring and the stopper owing to possible sliding of the saw-teeth onto the projections which ought to prevent their angular movement.

Moreover, the known structure provides for the opening of the pouring member to be closed by a collar which is fixed to the inner sleeve of the stopper and which, since it is connected rigidly to the stopper, is inserted in the opening of the pourer by a rotary movement during the screwing-up of the stopper.

Since the friction due to rotation between the surfaces which come into contact in the region of the closure of the pourer opening gives rise to a substantial removal of material, the seal is already compromised the first time the container is closed.

The object of the present invention is therefore to provide a closure structure which enables the closure operations to be performed predominantly by rotary screwing movements without damaging the sealing surfaces of the pouring member.

A further object of the invention is to achieve detachment of the security ring by the breakage of its connecting bridges as a result of a predominantly shearing action.

These and other objects which will become clear from the following description are achieved by the closure defined by the following claims.

The invention will now be described in greater detail with reference to a preferred embodiment thereof, described purely by way of non-limiting example and illustrated in the appended drawings, in which: Figure 1 is a partially vertically-sectioned side view of the closure according to the invention, Figure 2 is a partially vertically-sectioned side view of the stopper, Figure 3 is a partially vertically-sectioned side view of the pouring member, Figure 4 is a vertical section showing, on an enlarged scale, the sleeve with the security ring, to be fixed inside the stopper, Figure 5 is a section taken on the line V-V of Figure 4, Figure 6 is a partially vertically-sectioned side view of a variant of the pouring member of Figure 3, Figure 7 is a vertical section of the sleeve with the security ring modified in accordance with the variant of the pouring member shown in Figure 6, Figure 8 is a section taken on the line VIII-VIII of Figure 7.

With reference to Figures 1 to 5, the neck of a container la, for example, of a conventional liqueur bottle, is schematically indicated 1. Positioned on the mouth 2 of the neck 1 is a washer 3 which is intended to restrain, in conventional manner, with a first tubular portion 4, conventional spherical bodies which are not shown since they are not necessary for an understanding of the present invention, and which holds in position on the neck 1, by means of a second tubular portion 5, a pouring member 6 of known and conventional type, shown in greater detail in Figure 3.

The washer 3 also defines an annular abutment 7 on which a flange 8 of a conventional valve member 9 bears in abutment in the closure position.

The pouring member 6 has an internal cavity 10 with ducts 11 and an opening 12.

The external wall 6a of the pouring member 6 has a threaded portion 13 for screw engagement with a corresponding thread 14 formed on the internal wall 15a of a sleeve 15 shown in greater detail in Figure 4.

The sleeve 15 is positioned inside a cap-shaped stopper 16, shown in greater detail in Figure 2.

The top wall 16a of the stopper 16 has an inwardly- facing collar 17; as can be seen in Figure 1, the collar 17 is intended to close the opening 12 in a leaktight manner, by extending through an opening 15b of the sleeve 15.

The stopper 16 also has ribs 18 in its annular internal wall 16b for engaging under corresponding ribs 19 with saw-tooth-shaped cross-sections, carried by the external wall 15c of the sleeve 15.

The engagement is achieved by axial movement of the stopper 16 relative to the sleeve 15 when the sleeve has already been positioned on the pourer 6 by screwing of the threads 13 and 14.

The fitting of the stopper 16 on the sleeve 15 by an axial movement also brings about axial insertion of the collar 17 in the opening 12 upon assembly of the closure and thus prevents damage of the surface of the opening 12 which would occur if this insertion took place by rotation.

The rotational engagement between the stopper 16 and the sleeve 15 is ensured by a coupling between a plurality of sets of axial teeth 20 and 21 carried by the external wall 15c of the sleeve 15 and by the internal wall 16b of the stopper 16, respectively.

The sleeve 15 also has a ring, generally indicated 22, having the function of a security seal.

This ring is constituted by two half-rings 23 and 23a each of which is connected to the free edge 15d of the sleeve 15 by means of a plurality of breakable bridges 24.

Each half-ring 23,23a has radial projections 25 which extend circumferentially, spaced apart by vacant portions 26.

The radial projections 25 are intended to engage in the same number of corresponding circumferential recesses 27 formed in the external wall 6a of the pouring member 6 and delimited by end walls 28.

The cross-sections of the projections 25 are trapezoidal with a horizontal wall 25a facing towards the top 16a of the stopper 16 and a wall 25b which is inclined towards the container la so as to allow the projections to be inserted in the recesses 27 by the axial movement which results from the screwing of the sleeve 15 onto the pouring member 6.

The positions of the recesses 27 on the wall 6a of the pourer 6 are selected in a manner such that the recesses can house the projections 25 automatically upon completion of the screwing operation.

Upper walls 27a delimiting the recesses 27 in the axial direction also have respective flat and horizontal surfaces so that the corresponding walls 25a of the projections 25 can abut them when the stopper 16 is unscrewed and the ring 22 is to be broken upon initial opening.

After a short upward axial movement, the walls 25a abut the walls 27a of the recesses 27 and, as a result of further unscrewing, the projections 25 are then stopped against the walls 28 which delimit the recesses 27.

The ring 22 is thus prevented both from rotating and from moving axially.

The completion of the opening of the container by the removal of the stopper 16 thus brings about breakage of the bridges 24 substantially purely by shearing, by an operation which is reliable and is facilitated because it requires less effort by the operator than breakage predominantly by pulling.

With reference to Figures 6 to 8, it can be seen that the sleeve 15 has a ring 220 which is modified in comparison with that shown in Figure 4. The ring 220 is also preferably formed by two half-rings 230 and 230a, each of which has radial projections 250 extending circumferentially and spaced apart by vacant portions 260.

The radial projections 250 are intended to engage in the same number of corresponding circumferential recesses 270 formed in the external wall 6a of the pouring member 6 in a manner equivalent to that described with reference to the embodiment of Figures 3,4 and 5.

The profiles of the axial sections of the circumferential recesses 270 are substantially the same as those of the recesses 27 and are intended to perform the same function predominantly of locking the ring 220 axially relative to the pourer 6.

In a position beneath the radial projections 250, the ring 220 has a plurality of axial ribs 251 spaced apart circumferentially and facing towards the wall 6a of the pourer 6. Similarly, the wall 6a has corresponding axial ribs 271 positioned beneath the recesses 270 and also spaced apart circumferentially.

The axial ribs 251 and the corresponding ribs 271 are intended to interfere with one another as a result of the rotation of the stopper 16 and of the sleeve 15, helping to bring about breakage of the bridges 24 by shearing and hence detachment of the ring 220 from the body of the sleeve 15.

The closure is completed by a band 29 which may even be metallic and which is engaged on a step 30 of the pouring body 6 and wrapped around the neck 1 of the container in conventional manner.