Patent Publication Number: US-9884705-B2

Title: Cap for a container neck

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/824,991, filed on Mar. 18, 2013, which is a U.S. National Stage Entry of International Application No. PCT/EP2012/058163, filed on May 3, 2012, which claims the benefit of priority to French Patent Application No. 1153816, filed May 4, 2011. The contents of the above-referenced applications are expressly incorporated herein by reference each of these applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention concerns a cap for a container neck. 
     The invention is directed to plastic material caps that include a tubular skirt designed to be fixed removably around the free end ring of the neck of a container, typically by screwing-unscrewing. This means, among other things, screw caps very widely used to close bottles of mineral water or other foodstuff liquids. 
     BACKGROUND 
     In recant years, for both economic and ecological reasons, the height of these caps, i.e. the dimension of these caps in the direction of the central axis of their skirt, has ceaselessly increased, the skirt being reduced, so to speak, to a ring of very small height, the interior cylindrical surface of which is almost entirely occupied by a thread enabling the cap to be screwed onto the end ring of the container neck, which also has the smallest axial size. As a result of this, at present, some users have real difficulty in opening these caps, because the axial dimension of the exterior cylindrical surface of their skirt is so small that their fingers have difficulty grasping these caps effectively to unscrew them, in particular on first opening them, when it is very often necessary to break indicators of first opening, for example when a non-removable axial part of the skirt is retained around the container neck, while the rest can be unscrewed and removed, subject to breaking a line of weakening separating the non-removable skirt part and the removable skirt part. Moreover, the arrangements of the container neck linked to the indicators of first opening of the cap can accentuate the difficulties referred to above: thus the flange generally present at the base of the ring to limit how far the non-removable skirt part can drop makes it even more difficult to grasp the “small” removable skirt part. 
     Of course, one solution to the problem defined above would be to revert to the old dimensions of the caps and their associated rings. However, the object of the present invention is to propose an improved cap which, whilst being capable of being fixed removably to a present-day container neck, i.e. to a container neck the ring of which has a small axial dimension, is easier for users to manipulate, notably to open. 
     BRIEF SUMMARY 
     To this end, the invention consists in a cap for a container neck, including a tubular skirt which defines a central axis and which includes, successively along this axis, a first skirt part, provided internally with means for removably fixing it to the exterior surface of the container neck and a second skirt part including:
         a first axial end which connects the rest of the second skirt part to the first skirt part and which is provided internally with at least one surface adapted to abut axially against the free end of the container neck,   a second axial end which is axially opposite the first end and which is blocked transversely by an end wall of the cap, and   an intermediate part which extends axially between the first and second ends, from which project radially ribs substantially parallel to the axis and distributed in a direction peripheral to this axis and which, in an axial section half-plane of the skirt, have, outside said ribs, a radial dimension that is strictly less than the radial distance between the exterior cylindrical surface of the first skirt part and the interior radial end of the abutment surface or surfaces.       

     One of the ideas on which the invention is based is, so to speak, seeking to add, axially between the end wall of the cap and the axial part of the skirt, which is arranged internally to cooperate with the free end ring of a container neck for the purposes of removable fixing, an axial skirt part specific to the invention, in order to increase the overall exterior area of the skirt: accordingly, even in the presence of a container neck ring having a small axial dimension, manipulation of the cap is facilitated because one user&#39;s fingers can grasp a large axial extent on the exterior surface of the skirt to turn the cap. Moreover, the cap therefore has a more attractive exterior aesthetic, because of its increased overall volume in the direction away from the plugged container neck. Internally, the “added” skirt part between the end wall and the neck fixing skirt part has features aiming to cap it effectively in axial vertical alignment with the neck of the container, in the form of one or more surfaces that abut axially against the free end of the neck, in order to prevent the “added” skirt part being moved axially so as to line up radially with the ring of the neck. Moreover, given the cap manufacturing constraints, in particular constraints on moulding a plastic material constituting it, the “added” skirt part does not consist of a simple solid extension, which would notably cause hot spot problems during moulding, but, in accordance with the invention, features radially projecting ribs: when these ribs are present on the exterior cylindrical surface of the shirt part specific to the invention, they are advantageously grasped by the user&#39;s fingers to turn the cap and/or when these ribs are present on the interior cylindrical surface of the skirt part specific to the invention, they advantageously participate in the axial immobilization of this skirt part. In all cases, these ribs enable the skirt part specific to the invention to be manufactured in such a way that this skirt part has, outside the ribs, a moderate radial thickness, for example of the same order as the radial thickness of the neck fixing skirt part, this being the case whatever the axial dimension of the skirt part specific to the invention. 
     According to advantageous additional features of the cap in accordance with the invention, taken individually or in all technically possible combinations:
         the second skirt part has a total axial dimension of at least 50% of the axial dimension of the first shirt part occupied by the removable fixing means;   the cap further includes an annular sealing lip which is arranged coaxially with and inside the shirt and which projects axially from the end wall, being over the whole of its axial dimension at a radial distance from both the interior cylindrical surface of the first and second skirt parts and, if present, ribs projecting from the interior cylindrical surface of the intermediate part of the second skirt part;   the intermediate part of the second skirt part has interior and exterior cylindrical surfaces the diameters of which are strictly less than those of the interior and exterior cylindrical surfaces, respectively, of the first skirt part, while the or at least one of the abutment surfaces is delimited by an interior shoulder of the first end of the second skirt part, and while at least some or even all of the ribs project from the exterior cylindrical surface of the intermediate part of the second skirt part;   the exterior radial end of each of the ribs projecting from the exterior cylindrical surface of the intermediate part of the second skirt part is situated at a radial distance from the axis that is equal to or greater than the radius of the exterior cylindrical surface of the first skirt part;   each of the ribs projecting from the exterior cylindrical surface of the intermediate part of the second skirt part extends in the direction of the axis in line with an associated rib that projects from the exterior cylindrical surface of the first skirt part;   the abutment surface which is delimited by the interior shoulder of the first end of the second skirt part extends continuously around the whole of the interior periphery of this first end so as to form a sealing line against the exterior edge of the free end of the container neck;   the abutment surface which is delimited by the interior shoulder of the first end of the second skirt part is substantially frustoconical, being centred on the axis and converging toward the rest of the second skirt part;   some ribs project from the interior cylindrical surface of the intermediate part of the second skirt part and extend axially as far as the axial level of the abutment surface delimited by the interior shoulder of the first end of the second skirt part so that each of these ribs delimits at its axial end facing toward the first skirt part one of the abutment surfaces other than the abutment surface delimited by the interior shoulder;   the intermediate part of the second skirt part has interior and exterior cylindrical surfaces axially aligned with the interior and exterior cylindrical surfaces, respectively, of the first skirt part, while at least some or even all of the ribs project from the interior cylindrical surface of the intermediate part of the second skirt part and extend axially as far as the axial level of the first end of the second skirt part so that each of these ribs delimits at its axial end facing toward the first skirt part one of the abutment surfaces;   some ribs project from the exterior cylindrical surface of the intermediate part of the second skirt part and extend in the direction of the axis in line with an associated rib that projects from the exterior cylindrical surface of the first skirt part;   each of the ribs projecting from the interior cylindrical surface of the intermediate part of the second skirt part has:
           in section in a plane perpendicular to the axis a substantially rectangular contour in the lengthwise direction of which are opposed, on the one hand, an exterior radial edge of the rib which connects the rest of the rib so the interior cylindrical surface of the intermediate part of the second skirt part and, on the other hand, an interior radial edge of the rib, which is free, and   opposite each other in the direction of the axis, an axial edge that connects the rest of the rib to the end wall of the cap and an axial edge which delimits the abutment surface associated with the rib;   
           the interior radial edge of each of the ribs projecting from the interior cylindrical surface of the intermediate part of the second skirt part is provided with a stiffening enlargement which projects from one of the two faces of the rib, opposite in the widthwise direction of the substantially rectangular contour of this rib, in particular projecting from that of said two faces that faces away from the direction of screwing the cap around the container neck when the removable fixing means are screwing-unscrewing means;   the lengthwise direction of the substantially rectangular contour of each of the ribs projecting from the interior cylindrical surface of the intermediate part of the second skirt part is inclined relative to a direction radial to the axis, in particular inclined on the side of this radial direction that faces away from the direction of screwing the cap around the container neck when the removable fixing means are screwing-unscrewing means.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood on reading the following description given by way of example only and with reference to the drawings, in which: 
         FIG. 1  is a perspective view of a first embodiment of the invention; 
         FIG. 2  is an axial section of the cap from  FIG. 1 , the left-hand half of this section showing the cap on its own, while the right-hand half of this section shows the cap plugging a container neck; 
         FIG. 3  is a partial section taken along the line III-III in  FIG. 2 ; 
         FIG. 4  is a section taken along the line IV-IV in  FIG. 3 ; 
         FIG. 5  is a section taken along the line V-V in  FIG. 3 ; 
         FIG. 6  is a view analogous to  FIG. 3  showing a variant of the first embodiment of the invention; 
         FIG. 7  is a perspective view of a cap of a second embodiment of the invention; 
         FIG. 8  is an axial section of the cap from  FIG. 7 , the left-hand half of this section showing the cap on its own while the right-hand half of this section shows the cap plugging a container neck; 
         FIG. 9  is a partial section taken along the line IX-IX in  FIG. 8 ; 
         FIG. 10  is a section taken along the line X-X in  FIG. 9 ; and 
         FIGS. 11, 12 and 13  are views analogous to  FIG. 9  showing three variants of the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In  FIGS. 1 to 5  there is represented a cap  1  adapted to be removably fitted to a neck  2  of a container in order to plug this neck. 
     In practice, the neck  2  is either in one piece with the rest of the container, notably when the latter is a glass or plastic material bottle, or adapted to be fastened permanently to a wall of the container in an opening passing through that wall. 
     As described in detail hereinafter, the cap  1  has a globally tubular shape with a central longitudinal axis X-X. Similarly, the neck  2  has a globally tubular shape the central longitudinal axis of which coincides with the axis X-X when the cap  1  is plugging the neck. 
     For convenience, the remainder of the description of the cap  1  is oriented relative to the axis X-X, considering one terms “lower” and “bottom” to qualify a part of the cap that is directed axially toward the container when the cap is plugging the neck  2  of this container. Conversely, the terms “upper” and “top” correspond to the opposite axial direction. Similarly, the term “interior” qualifies a part of the cap  1  that is directed transversely toward the axis X-X while the term “exterior” corresponds to the opposite transverse direction. 
     The neck  2  includes a globally cylindrical body or ring  3  with a circular base, centred on an axis coinciding with the axis X-X when the cap  1  is plugging the neck. The top axial end  4  of the ring  3  is free, being open to the outside, whereas at its opposite axial end the ring  3  opens into the rest of the container. At its free end  4  the ring  3  delimits an edge  4 A where the product contained in the container is intended to be poured out and that is connected to the exterior lateral face  3 A of the ring  3  by an exterior edge  4 B. This exterior face  3 A of the ring  3  is provided successively from top to bottom with a helical thread  5 , a heel  6  and a flange  7 , all of which project radially outward. 
     As mentioned above, the cap  1  has a globally tubular shape, centred on the axis X-X. As can be seen clearly in  FIGS. 1 and 2 , the cap  1  is open at its lower end and is closed at its upper end by an end wall  10  which, in the embodiment considered here, is globally plane, having a disc-like shape centred on the axis X-X. From the exterior peripheral part of the end wall  10  there extend downward both an exterior tubular skirt  20 , which will be described in detail later, and an interior annular lip  30 , both centred on the axis X-X. The aforementioned lip  30  includes a free lower axial part  31  that is connected to the end wall  10  by the rest of the lip  30 , forming an upper axial lip part  32 , and which is provided on its exterior face with a radially projecting raised pattern  33 . This raised pattern  33  extends continuously around the whole of the exterior periphery of the lower lip part  31 , thus being adapted to bear in sealed manner against the interior face  3 B of the ring  3  of the container neck  2  when the cap  1  is plugging that neck, as in  FIG. 2 . As is the case in the embodiment considered in the figures, this sealing raised pattern  33  advantageously has an olive-shaped contour, and so the lip  30  is generally qualified as an “olive-lip”. 
     As can be seen clearly in  FIG. 2 , the skirt  20  includes two tubular axial parts centred on the axis X-X and in succession in the direction of that axis X-X, namely a bottom skirt part  40 , which will be described in detail next, and a top skirt part  50 , which will be described in detail later and connects the bottom part  40  to the end wall  10 . 
     As represented in  FIG. 2 , the interior cylindrical surface  40 A of the bottom skirt part  10  is provided with a thread  41  projecting radially inward and complementary to the exterior thread  5  of the ring  3  of the container neck  2 , thus enabling the cap  1  to be screwed onto and unscrewed from the neck. To facilitate grasping and turning the bottom skirt part  40 , the exterior cylindrical surface  40 B of this skirt part  40  is provided with radially projecting ribs  42  which, as can be seen clearly in  FIG. 1 , each extend lengthwise parallel to the axis X-X and which are distributed in a substantially uniform manner around the exterior periphery of the skirt part  40 . 
     Moreover, by way of an advantageous optional feature, the bottom skirt part  40  is extended downward by a tamper-evident strip  60 . In a manner known in itself, this strip  60  has an annular shape substantially centred on the axis X-X, its upper axial edge being connected to the lower axial edge of the skirt part  40  by a peripheral line  61  of weakening designed to break when the cap  1  is opened the first time. The line  61  of weakening is situated at an axial level that is both below the lower end of the thread  41  and above an interior raised pattern, not represented in the figures, of the tamper-evident strip  60 , which raised pattern is adapted to come to abut in the axially upward direction against the heel  6  when the cap  1  is opened the first time, in order to retain the strip  60  around the ring  3  in the axial direction, subject to the line  61  of weakening breaking. Once the tamper-evident strip  60  has been separated from the bottom skirt part  40 , more generally separated from the rest of the cap  1 , it tends under its own weight to descend axially along the ring  3  until it comes to rest bearing axially against the flange  7 . In that the technical features relating to the tamper-evident strip  60 , or more generally to similar means forming indicators of first opening, are well known in the field, they will not be described in more detail here. 
     As stated above, the top part  50  of the skirt  20  will now be described in more detail, in particular with reference to  FIGS. 2 to 5 . Accordingly, as indicated in  FIGS. 2, 4 and 5 , this top skirt part  50  is constituted, successively from the bottom upward along the axis X-X, of a bottom axial end  51  that connects the rest of the skirt part  50  to the bottom skirt part  40 , an intermediate axial part  52  that represents the largest axial part of the skirt part  50 , and a top axial end  53  that connects the rest of the skirt part  50  to the end wall  10 . 
     As can be seen clearly in  FIG. 5 , the intermediate part  52  of the skirt part  50  is not in axial alignment with the bottom skirt part  40  but, to the contrary, the respective diameters of its interior cylindrical surface  52 A and its exterior cylindrical surface  52 B are strictly less than the diameters of the interior cylindrical surface  40 A and the exterior cylindrical surface  40 B, respectively, the skirt part  40 . As a result of this the bottom end  51  of the skirt part  50  accommodates the changing diametral dimension of the skirt  20 , having a globally inwardly shouldered shape, as can be seen clearly in  FIG. 5 . In particular, as is clear from  FIG. 5  and from the left-hand half of  FIG. 2 , the bottom end  51  of the skirt part  50  includes an interior shoulder  54  that runs over the whole of the interior periphery of this end  51  and delimits a lower surface  54 A. In other words, this surface  54 A, which faces toward the bottom skirt part  40 , runs around the whole of the interior periphery of the top skirt part  50  and, in the embodiment considered in the figures, projects radially inward from the top axial end of the bottom skirt part  40 . 
     As is the case in the embodiment considered in the figures, the aforementioned surface  54 A is advantageously frustoconical, being centred on the axis X-X and converging toward the intermediate part  52  of the top skirt part  50 . 
     As can be seen clearly in the right-hand part of  FIG. 2 , as well as in  FIGS. 4 and 5 , the aforementioned surface  54 A is sized, in particular with regard to its radial dimension, so as to come to bear axially against the free end  4  of the ring  3  of the container neck  2  when that neck is plugged by the cap  1 , to be more precise to come to bear against the edge  4 B of this free end. As a result, by virtue of downward axial bearing of the top skirt part  50  against the free end  4  of the ring  3 , the cap  1  is prevented from being driven axially, relative to the container neck  2 , lower than it is in  FIGS. 2, 4 and 5 . Moreover, in that this surface  54 A extends continuously around the whole of the interior periphery of the shirt  20 , the axial bearing of the top skirt part  50  against the free end  4  of the ring  3  is advantageously sealed in that the cooperation between the surface  54 A and the edge  4 B of the free end  4  forms a peripheral sealing line. 
     Externally, the reduction in the diametral dimension of the top skirt part  50  relative to the bottom skirt part  40  implies that the exterior cylindrical surface  52 B of the intermediate part  52  is situated radially inside the cylindrical envelope defined by the exterior cylindrical surface  40 B of the bottom skirt part  40 , as can be seen clearly in  FIG. 5 . However, as can be seen clearly in  FIG. 1 , this inward radial [shrinkage] of most of the top skirt part  50  is, so to speak, compensated by the presence of ribs  55  that project radiantly from the exterior cylindrical surface  52 B of the intermediate part  52  of the skirt part  50  and that extend on this exterior cylindrical surface  52  parallel to the axis X-X, being distributed, advantageously in a substantially uniform manner, around the exterior periphery of this surface  52 B. In practice, as can be seen clearly in  FIG. 3 , for the aforementioned compensation to be complete, the exterior radial end  55 A of each of these ribs  55  is situated at a radial distance from the axis X-X that is equal to, or even greater than, the radius of the exterior cylindrical surface  40 B of the bottom skirt part  40 : as a result, when the user applies their fingers around the skirt  20 , each finger can easily bear radially against, at one and the same time, the bottom skirt part  40  and the ends  55 B of the ribs  55  on the top skirt part  50 . This offers the user&#39;s fingers a large axial extent for manipulating the skirt  20 , notably for turning it on itself about the axis X-X to screw or unscrew it relative to the ring  3  of the container neck  2 , in the sense that this radial extent is not limited to that of the bottom skirt part  40 , but adds to the latter the axial extent of most of or even virtually all of the top skirt part  50 . Of course, this arrangement also enables improved centring of the cap  1  in the machines employed to place it initially on the container neck  2 , such as in a screwing cone. 
     As is the case in the embodiment considered in the figures, each of the ribs  42  provided on the exterior surface  40 B of the bottom skirt part  40  advantageously extends in the direction of the axis X-X in alignment with one of the ribs  55 , as can be seen clearly in  FIG. 1 . By sizing the ribs  42  so that their exterior radial end is axially in line with the exterior radial end  55 A of the associated rib  55 , most or even virtually all of the exterior face of the shirt  20  produces in the user a ribbed raised pattern sensation that is homogeneous in the direction of the axis X-X. This amounts to saying that the depth of the ribs  55 , i.e. their projecting radial dimension relative to the exterior cylindrical surface  52 B of the intermediate part  52  of the top skirt part  50 , is greater than that of the ribs  42  relative to the exterior surface  40 B of the skirt part  40 , as can be seen clearly in  FIG. 1 . The result of this is a singular aesthetic. 
     It will moreover be noted that, because of the presence of the ribs  55 , obtaining the large axial extent for the skirt  20 , as explained above, does not imply a massive construction of the top skirt part  50  in the sense that, in axial half-section of the skirt  20 , as indicated in  FIG. 5 , the thickness e 52  of the intermediate part  52 , in other words its radial dimension, outside the ribs  55 , this dimension separating from each other the interior cylindrical surface  52 A and the exterior cylindrical surface  52 B of the intermediate part  52 , is not equal to, but strictly less than, the radial distance d 20  between the exterior cylindrical surface  40 B of the bottom skirt part  40  and the interior radial end of the surface  54 A. This reflects the fact that, although the top skirt part  50  is used directly, by way of its shouldered surface  54 A, to form an axial abutment relative to the ring  3  of the container neck  2 , the thickness of this skirt part  50  is, to compensate, not significantly increased toward the outside around the whole of the exterior periphery of this skirt part  50 . Such a continuous additional thickness around the whole of the exterior periphery of the shirt part  50  would lead, during manufacture of the cap  1 , to the occurrence of hot spots within the mass of material constituting this top skirt part, notably within a plastic material if the cap  1  is manufactured by moulding such a plastic material. 
     In practice, it is clear that the top skirt part  50  can then be manufactured with a large axial dimension, thus making it possible to reinforce as much as required the obtaining of a large overall axial extent for the skirt  20 , with the advantages explained above, linked to manipulating the cap  1 . It will be noted that the large axial extent of the skirt  20  is obtained although the bottom skirt part  40  has the exact axial dimension, in the sense that the thread  41  of this skirt part  40  is adapted to cooperate with the thread  5 , while the latter has a small axial dimension, which amounts to saying that the ring  3  is a ring having an axial dimension that is intent locally as small as possible, reflecting the considerations set out in the introductory part of the present document. In other words, the cap  1  has the advantage that it can be attached to the ring  3  while the latter has a small axial dimension, at the same time as offering the user a skirt  20  having a large axial extent for easy manipulation of the cap  1 . In practice, in terms of advantageous dimensions, the top skirt part  50  has a total axial dimension equal to at least 50%, or even 100%, or more, of the axial dimension of the thread  41  of the bottom skirt part  40 . 
     It will moreover be noted that the top end  53  of the top skirt part  50  is not connected directly to the top part  32  of the lip  30 , which would limit the bending capabilities of this lip  30 , used so that the raised pattern  33  bears in sealed manner against the interior face  3 B of the ring  3  of the container neck  2  when that neck is plugged by the cap  1 . To the contrary, as can be seen clearly in  FIG. 5 , the interior cylindrical surface of the skirt part  50  is, over the whole of its axial dimension, at a radial distance from the upper part  32  of the lip  30 . 
     By way of advantageous optional features, the interior cylindrical surface  52 A of the intermediate part  52  of the top skirt part  50  is provided with radially projecting ribs  57 . The benefit of these optional ribs  57  is linked to the fact that, in the direction of the axis X-X, each of these ribs  57  extends to the axial level of the surface  54 A, as can be seen clearly in  FIGS. 2 and 4 , so that each of these ribs  57  delimits at its lower axial end a surface  57 A which, when the cap  1  is plugging the container neck  2  as in  FIG. 2 , abuts in the axially downward direction against the free end  4  of the ring  3  of the container neck  2 , to be more precise against the edge  4 A of this free end  4 . This amounts to saying that the surface  54 A leads locally, at the radial level of each of the ribs  57 , onto the corresponding surface  57 A, these surfaces  57 A thus reinforcing the axial abutment of the top skirt part  50  against the free end  4  of the ring  3  and thus enabling a higher tightening torque to be applied to the cap  1  when it is screwed around the container neck  2 . In practice, it will be noted that the surface  54 A and the surfaces  57 A are arranged, so that, on screwing the cap  1  all the way around the container neck  2 , the surface  54 A interferes with the exterior edge  4 B of the free end  4  of this neck, before the surfaces  57 A bear against the edge  4 A: this favours the sealed bearing of the skirt part  50  on the container neck  2  by way of the cooperation between the shouldered surface  54 A and the edge  4 B of this neck, whereas, thanks to the subsequent cooperation between the surfaces  47 A and the edge  4 A at the end of the container neck the risk of the skirt part  50  flaring radially outward, by sliding of the bottom end  51  of the shirt part  50  against the edge  4 B of the container neck  2 , as a result in particular of the application to the cap of too high a tightening force, is significantly reduced. To preserve the flexibility of the sealing lip  30 , each of the ribs  57  is at a radial distance from the upper part  32  of this lip  30 , as can be seen clearly in  FIG. 3 . This radial distance, denoted Δ 57  in  FIG. 3 , is advantageously made greater than the projecting radial dimension of the raised pattern  33  relative to the rest of the lip  30 , so that, on extraction of the cap  1  from the mould, the raised pattern  33  does not rub against the elements for moulding the ribs  57 , which would have the harmful consequence of scratching this raised pattern  33  and therefore compromising its sealing performance. 
     It is again emphasized here that the ribs  57 , just described above, are optional. Accordingly, in  FIG. 6  there is represented a variant of the cap  1  without these ribs  57 . This amounts to saying that, for this embodiment, the top skirt part  50 ′ includes a top end  53 ′ identical to the top end  53  of the skirt part  50 , a bottom end  51 ′, notably with an interior shoulder  54 ′ delimiting an axial abutment surface  54 A′, that is identical to the bottom end  51 , with its shoulder  54  and its surface  54 A, of the skirt part  50 , and an intermediate part  52 ′ which has both a thickness e 52 ′ identical to the thickness e 52  of the intermediate part  52  and an exterior cylindrical surface  52 B′, notably with exterior ribs  55 ′, identical to the surface  52 B, with its ribs  55 , of the part  52 , but the interior cylindrical surface  52 A′ of which is smooth, as can be seen clearly in  FIG. 6 . It will be noted that, in a plane identical to that of  FIG. 5 , this variant shown in  FIG. 6  has a section identical to that shown in  FIG. 5  for the cap  1  from  FIGS. 1 to 5 , which explains why, in  FIG. 5 , there are shown conjointly the reference numbers associated with the cap  1  and those associated with its  FIG. 6  variant. Of course, the components of the cap of the  FIG. 6  variant other than its too skirt part  50 ′ are identical to those of the cap  1  from  FIGS. 1 to 5  and therefore bear the same reference numbers. 
     In  FIGS. 7 to 10  there is represented a cap  101  adapted to be removably attached around the container neck  2  in order to plug the latter in substantially the same way as the cap  1 . As can be seen clearly on comparing  FIGS. 1 to 5  and  FIGS. 7 to 10 , the cap  101  differs from the cap  1  only in the top part  150  of its shirt  120 , while its end wall  110 , the bottom part  140  of its skirt  120 , its sealing lip  130  and its tamper-evident strip  160  are identical to the end wall  10 , bottom skirt part  40 , sealing lip  30  and tamper-evident strip  60 , respectively, of the cap  1 . These components common to the cap  1  and the cap  101  will not be described further with reference to  FIGS. 7 to 10  on the understanding that, in the aforementioned figures, the elements of the cap  101  featured identically in the cap  1  bear the same reference numbers as those of the cap  1  increased by 100. 
     Considering further the top part  150  of the skirt  120 , it is seen that, differing in this respect from the skirt part  50 , the skirt part  150  does not have a reduced diametral dimension relative to the bottom skirt part  140  but to the contrary, as can be seen clearly in  FIGS. 8 and 10 , the interior cylindrical surface  152 A and the exterior cylindrical surface  152 B of the intermediate part  152  of the skirt part  150  are aligned axially with the interior cylindrical surface  140 A and the exterior cylindrical surface  140 B, respectively, of the bottom skirt part  140 . The bottom end  151  of the skirt part  150  is, without radial discontinuity, in axial alignment with the top skirt part  150  and the bottom skirt part  140 . Accordingly, the top end  153  of the skirt part  150  connects the rest of this skirt part  150  to the end wall  110  which, given the greater diametral dimensions of the skirt part  150  compared to the skirt part  50 , has an outside diameter greater than the outside diameter of the end wall  10  of the cap  1 . This amounts to saying that, as can be seen clearly in  FIG. 7 , the skirt  120  has over substantially all of its axial dimension a constant diametral dimension, the exterior face of this skirt  120  thus being usable, over the whole of its axial dimension, by the fingers of the user to manipulate the cap  101 , notably to turn it on itself about the axis X-X. Moreover, to facilitate turning it, the exterior face of the skirt  120  is advantageously ribbed: as can be seen clearly in  FIG. 7 , this amounts to saying that the exterior cylindrical surface  152 B of the intermediate part  152  of the top skirt part  150  is provided with optional ribs  155  projecting radially outward which, in the direction of the axis X-X, are in rectilinear alignment with an associated optional rib  142  that projects radially from the exterior cylindrical surface  140 B of the bottom skirt part  140 , these ribs  155  and  142  being regularly distributed, advantageously in a substantially uniform manner, around the exterior periphery of the skirt  120 . 
     As can be seen clearly in  FIGS. 8 to 10 , the interior cylindrical surface  152 A of the intermediate part  152  of the top skirt part  150  is provided with radially projecting ribs  157  that extend axially from the axial level of the top end  153  to the axial level of the bottom end  151 . In other words, each of the ribs  157  has opposite each other in the direction of the axis X-X, a top axial edge  157 A that connects the rest of the rib  157  to the end wall  110 , being moulded in one piece with this end wall in the embodiment considered in the figures, and a lower axial edge which, at least in its exterior part, delimits a free surface  157 B facing toward the bottom skirt part  140 . Moreover, in section in a plane perpendicular to the axis X-X, as represented in  FIG. 9 , each of the ribs  157  has a substantially rectangular contour in the lengthwise direction of which are opposed the radial edges of the rib, namely, on the one hand, an exterior radial edge  157 C that connects the rest of the rib  157  to the interior cylindrical surface  152 A of the intermediate part  152  of the top skirt part  150 , being moulded in one piece with this interior cylindrical surface  152 A in the embodiment considered in the figures, and, on the other hand, an interior radial edge  157 D that is free. 
     Accordingly, the ribs  157  stop downward axial movement of the top skirt part  150  relative to the container neck  2  when the latter is plugged by the cap  101 , as in  FIG. 8 : to this end, the lower surface  157 B of each of the ribs  157  constitutes a downward axial abutment surface for the skirt part  150  and thus for the whole of the cap  101 . In particular, in a similar manner to the ribs  57  of the cap  1 , the surfaces  157 B of the ribs  157  are adapted to bear axially against the edge  4 A of the free end  4  of the ring  3  of the container neck  2 . As in the embodiment considered in the figures, each of these surfaces  157 B, all of which are inscribed within the same plane perpendicular to the axis X-X, is advantageously extended outward by an optional downwardly inclined surface  154  that is delimited by the interior part of the lower axial edge of the rib  157  and that bears on a local portion of the edge  4 B of the free end  4  of the ring  3  when the container neck  2  is plugged by the cap  101 . 
     It will be noted that, in that the ribs  157  are distributed about the interior periphery of the top skirt part  150 , being spaced from each other around that periphery, the axial abutment effect of these ribs does not imply a massive construction of the top skirt part  150 : in other words, in a similar manner to what is described above for the skirt part  50 , in axial half-section of the skirt  120 , the intermediate part  152  of the skirt part  150  has, outside the ribs  155  and  157 , a thickness e 152 , i.e. a radial dimension, than is strictly less than the radial distance d 120  between the exterior cylindrical surface  140 B of the bottom skirt part  140  and the interior radial end of the abutment surfaces  157 B, as indicated in  FIG. 10 . 
     Moreover, and also as can be seen clearly in  FIG. 10 , it will be noted that the upper edge  157 A of each of the ribs  157  is not connected directly to the upper axial part  132  of the sealing lip  130  but, to the contrary, is at a radial distance from this lip part  132  over the whole of the axial dimension of this lip part  132 : in a similar manner to what has been described for the ribs  57  of the cap  1 , this arrangement preserves the flexibility of the sealing lip  130 . Moreover, the radial distance denoted Δ 157  in  FIG. 9  between the interior radial edge  157 D of each rib  157  and the upper part  132  of the sealing lip  130  is advantageously made greater than the projecting radial dimension of the raised pattern  133  provided on the exterior surface of the lower part  131  of the lip  130 : as a result, as already mentioned for the ribs  57  of the cap  1 , the lip  130  can be extracted from the mould without risk of its sealing raised pattern  133  interfering with the arrangements necessary for moulding the ribs  157 , thereby preventing scratching of this raised pattern  133 . 
     With regard to the foregoing explanations, ii is clear that the cap  101  has substantially the same advantages as the cap  1  in so far as concerns its advantageous capability to provide a large axial extent for its skirt  120  whereas its bottom skirt part  140  has the exact axial dimensions, i.e. is designed to cooperate with the ring  3 , which has a particularly small axial dimension. In particular, the values proposed above for the axial dimensional ratio between the skirt parts  40  and  50  also prove relevant for the skirt  120 : in other words, the skirt part  150  advantageously has a total axial dimension of at least 50%, or even 100%, or more, of one axial dimension of the thread  141  of the bottom skirt part  140 . 
     By way of an advantageous optional arrangement, the interior radial edge  157 D of each rib  157 , as seen in section in a plane perpendicular to the axis X-X, does net have a contour that is rigorously inscribed with the rest of one globally rectangular contour of the rib  157  but, as represented in  FIG. 9 , has an enlarged contour on either side of the main faces of the rib  57 , i.e. the opposite faces in the widthwise direction of the substantially rectangular contour of the rib. This amounts to saying that, overall, in section in a plane perpendicular to the axis X-X, each rib  57  has a T-shaped overall contour with the crossbar of this T-shape corresponding to the interior radial edge  157 D. In other words, the interior radial edge  157 D includes two enlargements  158  and  159  projecting from a respective one of the two main faces of the rim  157 . These enlargements  158  and  159  extend axially over the whole of the axial dimension of the rib  157 , in particular as far as its lower axial edge, thus extending the abutment surface  157 B in a direction orthoradial to the axis X-X. As well as extending the abutment surface  157 B, these enlargements  158  and  159  have the advantage of stiffening each rib  157  at the level of its interior radial edge  157 D. In this way, when the cap  101  is screwed all the way onto the container neck  2  and, as explained above, the surfaces  157 B and  154  of the ribs  157  come to bear axially against the free end  4  of the ring  3  of this container neck, the enlargements  158  and  159  limit the deformation in bending suffered by the ribs  157  through rotary rubbing contact against the free end  4  of the ring  3 . It is thus clear that the stiffening effect of the enlargement  158  is particularly useful in that this enlargement  158  projects from the face of the rib  157  facing in the opposite direction to the direction indicated by the curved arrow S in  FIG. 9  of screwing the cap  101  around the container neck  2 . Of course, ever if to a lesser extent, the opposite enlargement  159  of each rib  157  also participates in limiting the deformation in bending of the rib. 
     On the basis of the immediately preceding considerations, the benefit of the two variants from  FIGS. 11 and 12  is clear. In these  FIGS. 11 and 12 , the respective ribs  157 ′ and  157 ″, which are functionally similar to the rib  157  described until now, do not have, in a plane perpendicular to the axis X-X, a T-shaped contour, like the rib  157 , but L-shaped and J-shaped contours, respectively. In other words, each of these ribs  157 ′ and  157 ″ does not have, at its interior radial edge, two opposed enlargements, like the enlargements  158  and  159 , but a single enlargement  158 ′,  158 ″ that advantageously projects from the main face of the rib  157 ′,  157 ′″ that faces away from the screwing direction S. 
     In  FIG. 13 , a variant  157 ′″ of the rib  157  has neither of the enlargements  158  and  159 , but differs from the rib  157  in that the lengthwise direction of its rectangular contour is not in a direction radial to the axis X-X, but is inclined relative to that radial direction. To reinforce the effect of resistance to deformation of the rib  157 ′″, the aforementioned inclination is advantageously provided on the side of the aforementioned radial direction, which faces away from the screwing direction S. 
     Of course, where the variant described above with reference to  FIGS. 11 to 13  are concerned, the components of the corresponding caps other than the ribs  157 ′,  157 ″ and  157 ′″ are identical to those of the cap  101  and therefore bear the same reference numbers in the case of those that can be seen in these  FIGS. 11, 12 and 13 . 
     Diverse arrangements and variants of the caps  1  and  101  and their variants described until now may also be envisaged. For example:
         the arrangements relating to the ribs  157 ,  157 ′,  157 ″ and  157 ′″ may be combined with each other; of course, some or all of these arrangements may be applied to the ribs  57  of the cap  1 ;   where the exterior ribs  42 ,  55 ,  142  and  155  are concerned, it will be noted that their profile is not limiting on the present invention; accordingly, compared to what can be seen in the figures, the free end of these ribs may be made more angular or more rounded; and/or   embodiments other than the threads  41  and  141  may be envisaged with regard to the removable fixing of the bottom part  40 ,  140  of the skirt  20 ,  120 ; for example, this bottom skirt part may be provided internally with one or more clips designed to wedge against an exterior raised pattern projecting from the free end of the ring of the container neck.