Patent Abstract:
A connecting device including three elements, namely: a core which is housed in an inner part and an outer part. The core includes a head having a truncated-cone-shaped part and a rod having, for example, one of the two sides of a collar connected thereto, the other side being connected to the outer part. The inner part is snap engaged in the outer part and is simultaneously detached from the core. The head is shaped such that, in a closed configuration, the head inhibits the engagement element such that the device locks when the rod is pulled.

Full Description:
BACKGROUND 
     (1) Field of Embodiments 
     The present invention refers to a self-locking connecting device according to the preamble of independent claim  1 . 
     The privileged fields of application of this kind of device are jewelry and clockmaking. 
     (2) Description of Related Art 
     The basic problem that is encountered is the perfect safety of the connection and the reliability of the latter, combined, first of all, with a simple, quick, and comfortable operation of the device, furthermore with a rational and subtle construction of the latter that allows a manufacture at minimum cost and a genuine polyvalence both in its applications and in its usage, and ultimately, more particularly if it is intended for use in jewelry or clockmaking, with a sober, discrete, and attractive esthetic, which implies a harmonic shape and overall dimensions that are reduced to the minimum. 
     The types of connecting devices known in the art are quite numerous. However, they are still affected by more or less marked drawbacks with regard to all or part of this problem. 
     Among the best known connecting devices, commonly called clasps, the spring ring clasp may be cited, which is formed of a hollow ring that is cut on a segment and of a pin that can be operated to open or close that segment and has the same curvature as the latter, which pin is under the action of a spring accommodated in the ring. The latter is attached to one end of a necklace. The loop of a chain link or of another ring connected to the second end of the necklace can be inserted therein through the open segment while the pin that closes the ring is moved against the action of the spring. The pin is then released, thereby reclosing the ring. This system is thought to be inelegant as it is ill adapted to the shape of the necklace, bulky, and heavy. Moreover, it often requires an additional safety. 
     Moreover, when the clasp is fastened to a short necklace, it is located behind the neck of the person wearing it. In order to manipulate the clasp of the necklace, the person has to operate blindly and his or her arms are in a tiring position. If the person fails to insert the two elements of the clasp into each other right away, successive trials and fumbling will be the result. This uncomfortable manipulation may lead to an incomplete lock, and the clasp may sometimes be undone by accident. 
     FR-A-2 694 485 discloses a locking device comprising a body with two pivoting elements and a male end portion whose shape corresponds to that of a recess in a housing of the body. When the male end portion is introduced into the recess of the body, a key can be pivoted and placed in a receptacle of the end portion. A cover ensures the closure by preventing an involuntary retraction of the key. 
     FR-A-2 531 322 describes a clasp for a necklace chain that comprises two pieces sliding one in the other, namely an outer sleeve provided with a slot for introducing an end link of the chain and an inner slide element provided in its upper part with a notch for receiving the link. This clasp further comprises a locking tooth that is connected to the slide element and is engaged in an aperture of the slide element in the locking position. 
     However, these clasps do not offer an acceptable solution to the aforementioned drawbacks. 
     FR-A-2 611 452 discloses a clasp composed of a male part and a female part which cooperate with each other by the implementation of a snap function. This clasp provides an improvement in that it seems to offer a satisfactory closure safety and to allow quite an easy operation by feel. In contrast, the opening operation is very uncomfortable, the production, i.e. the manufacture of the clasp is delicate and costly, and its esthetic is all but fortunate. 
     SUMMARY 
     The present invention aims to provide a global rather than a partial solution to the problem laid out in the introduction, in the sense that it meets each one of the aspects of this problem. 
     This is accomplished by the means defined in the characterizing part of independent claim  1 , the dependent claims relating to preferred means of realization of the invention. 
     Thus, the closure, for example of a piece of jewelry such as a necklace, is safe and reliable. Opening and closure are achieved in a comfortable, simple, and quick manner. The device is esthetically perfect due to its general shape that may advantageously be cylindrical or prismatic, and its size is minimal. Finally, the manufacturing costs of its component parts are reduced to minimum on account of their simple shapes. 
     This series of advantages is completed by that of polyvalence both in its application and in its usage since through its concept, the device of the invention may be used—to cite only some examples among a multitude of others—e.g. for the attachment of an USB key, a mobile telephone, a pen, a key ring, a decorative element, of a leash to a necklace for a pet or other attachments of the kind, a hook to the end of a fishing line, in each case in the adapted dimensions which may range from the smallest to the largest. It will be noted in this context that the device, or more precisely one element of the latter, may be integrated in the object to be connected itself or used for fastening interchangeable elements of the object, e.g. a pendant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Now, by way of non-limiting examples, two embodiments of the connecting device according to the invention will be described with reference to the attached drawing, in which 
         FIG. 1  is an axial section of the device according to a first embodiment in the assembled, i.e. closed state, 
         FIG. 2  is a top view of the male part of the device, 
         FIG. 3  is an axial section of the device in an intermediate state (during its opening or closure), 
         FIG. 4  is an axial section of the device in the open state, 
         FIG. 5  is a sectional view in analogy to that of  FIG. 1 , illustrating a particular characteristic of the safety, 
         FIG. 6  is an axial section of the device according to a second embodiment in the closed condition, and 
         FIGS. 7A ,  7 B;  8 A,  8 B show exemplary uses of the device. 
     
    
    
     DETAILED DESCRIPTION 
     It is seen in  FIG. 1  that the self-locking connecting device, hereinafter called clasp by convention, comprises three main parts, namely a female part  2 , a male part  3  and an auxiliary part or core  1 . 
     In the first embodiment illustrated here, core  1  with axis  1 A is composed of a cylindrical stem  4  having a lower surface  4 A and of a head  5  formed of a frustoconical portion  5 A whose large diameter is heightened by a base  5 B. 
     Female part  2  with axis  2 A is a cap particularly the upper surface  2 B of which may be provided with attachment points or eyelets. An inner recess results from a cylindrical bore  6  whose diameter is defined so as to be able to form a guide for male part  3  (see below), this bore  6  opening onto a cylindrical bore  7 , whose diameter is larger than the diameter of bore  6 , via a frustoconical ramp  8 bis. The lower side of bore  6  opens toward the exterior via a ramp  8  that is analogous to ramp  8 bis, whose respective roles will be discussed below. 
     Male part  3  with axis  3 A is a collet or sleeve having an internal bore  3 B that extends from side to side and opens in a conical shape  12  (on the upper side). This collet has a lower portion  9  (whose lower radial surface is referenced by  3 C) that is followed by an upper portion  10 , thus forming a shoulder  9 A. This upper portion has at least two longitudinal slits  10 C (see also  FIG. 2 ) which terminate at the height of said shoulder  9 A approximately. The planes of symmetry (not shown) of each one of the slits comprise axis  3 A, so as to form at least two fingers that are elastically deformable and dimensioned accordingly. For an application in jewelry, the number of slits, and consequently of fingers, is advantageously four. However, this number may be greater, for example equal to six, as shown in  FIG. 2  (the single reference  10  being used to designate the entire tubular part provided with slits or one or another of the fingers). The ends of fingers  10  open to form each a part of a corolla  10 A having frustoconical external and internal surfaces  11  and  12 , respectively (aforementioned conical opening shape), and an upper crown  10 B (reference numeral  10 A may also designate the corolla as a whole). 
     Core  1  extends inside male part  3  and projects therefrom, on its upper side, by base  5 B essentially and, on its lower side, by a (non-referenced) portion of stem  4 , while it is observed that in alternative embodiments, stem  4  may be dimensioned such that its lower surface  4 A is flush or approximately flush with the lower surface  3 C of part  3 , or even recessed from the latter. Frustoconical portion  5 A of head  5  is partly facing frustoconical surface  12  of corolla  10 A, whereas frustoconical surface  11  of the corolla is partly facing ramp  8 bis of female part  2 . 
     Starting from the clasp in the assembled, i.e. closed state as illustrated in  FIG. 1 , its operation will now be described while it is first observed that female part  2  is e.g. connected to one of the ends of a necklace while the other end of the necklace is connected to stem  4  of core  1 , which can slide inside female part  2  within the limits of a clearance that may be provided, i.e. of a space between the upper (non-referenced) surface of head  5  and the (non-referenced) surface of female part  2  located opposite the head. 
     Referring to  FIG. 3 , it is understood that the clasp is opened by an axial traction F 3 (O) applied to male part  3  while female part  2  is being maintained in place, i.e. concomitantly subjected to a contrary reaction force F 2 (O). In a first phase (which stage is not graphically represented), corolla  10 A is clamped between head  5  of core  1  and ramp  8 bis of female part  2 , frustoconical surface  5 A bearing on frustoconical surface  12  and frustoconical surface  11  bearing on ramp  8 bis. In a second phase, fingers  10  are elastically bent under the effect of the radial components of the aforementioned forces, surface  11  sliding on ramp  8 bis. In a third phase, the most peripheral surface or edge (not referenced) of corolla  10 A slides along bore  6  while being guided by the latter, while the edge (not referenced) formed between bore  3 B and frustoconical surface  12  of corolla  10 A uniformly approaches the envelope of stem  4  (position as shown in  FIG. 3 ) or may even contact the latter slightly. 
     As they arrive at the height of ramp  8 , corolla  10 A and hence fingers  10  progressively open to return to their initial positions when the assembly of the two parts  1  and  3  is extracted from female part  2  ( FIG. 4 ). 
     The closure (in order to connect, in the example, the two ends of the necklace) is obtained by snap action upon performing the inverse operations of those carried out in the opening operation and that have just been described, an axial pressure force F 3 (C) being applied to male part  3  with core  1  while female part  2  is retained, i.e. concomitantly subjected to a contrary reaction force F 2  (C) (see  FIG. 3 ). In a first phase, corolla  10 A bearing on ramp  8  has the effect of contracting fingers  10  until they reach the position shown in  FIG. 3 . Then, the axial movement of part  3 , along with part  1 , along bore  6  continues, corolla  10 A progressively opening from the moment it arrives at the height of ramp  8 bis until fingers  10  reach the final closure position as shown in  FIG. 1 . 
     It is understood that all elements of the clasp are dimensioned such that the operations of snapping in and releasing the parts (parts  1  and  3 , on one hand, and part  2 , on the other hand) can be performed efficiently and without wedging. 
     When a traction is applied to at least one necklace end, i.e. to parts  1  and/or  2  (see forces F 2 (B), F 1 (B) in  FIG. 5 , which illustrates the safety of the closure by self-locking action), head  5  of core  1  bears on corolla  10 A of fingers  10  of part  3  (i.e. in this embodiment, at least part of the frustoconical surface  5 A bears on surface  12 ). This causes the displacement of part  3  until at least part of surface  11  of corolla  10 A of fingers  10  in turn bears on ramp  8 bis of female part  2 . Thus, any outward movement of core  1 , i.e. in the direction of force F 1 (B) becomes impossible. In other words, the snap means are neutralized. With core  1  locked in this position, the clasp remains closed. 
       FIG. 6  is an axial section in analogy to  FIG. 1  of the device in the closed state, however according to a second embodiment designated by the general reference  100 , with axis  100 A. This device comprises an auxiliary element or core  50  with axis  50 A, a female part  60  with axis  60 A and a male part  70  with axis  70 A. In this state, the axes of this element and of these parts coincide with each other and with axis  100 A of the device. 
     Core  50  is formed of a cylindrical stem  51  having a lower surface  52  and, on the opposite side, a head  53  composed of a frustoconical portion  54  whose large diameter is heightened by a basis that is dimensioned so as to form an abutment  56  (whose function will be discussed below) together with frustoconical surface  54 , whereas end portion  57  is convex. 
     Female part  60  is a preferably cylindrical cap that is destined to be connected to one end of a necklace or to a pendant, for example. An inner recess results from a cylindrical bore  61  whose diameter is defined so as to be able to form a guide for male part  70  (see below), this bore  61  opening onto a cylindrical bore  62 , whose diameter is larger than the diameter of bore  61 , via a frustoconical ramp  63 . The lower side of bore  61  opens toward the exterior via a ramp  64  that is analogous to ramp  63 . 
     Male part  70  is in the form of a two-part collet or sleeve  71 ,  72  having an inner bore  73  that extends from side to side and opens onto the exterior via flanks  76  (on the upper side) and a milling  80  (on the lower side). Upper part  72  connects to lower part  71  and forms a shoulder  78  with the latter. The upper part of the collet has at least two longitudinal slits (not referenced here) which, in the present example, terminate at the height of shoulder  78 . The planes of symmetry (not shown) of each one of the slits comprise axis  70 A, so as to form at least two fingers that are dimensioned so as to be elastically deformable. As in the first embodiment, the number of slits and therefore of fingers is four (and here also, the same reference  72  is being used to designate the fingers). The ends of fingers  72  open to form a corolla  74  having internal and external frustoconical surfaces  76  and  77 , respectively, and an upper crown  75 . 
     Core  50  extends inside male part  70  and on its upper side projects therefrom by its base  55 ,  57 . Here, lower surface  52  of stem  51  is flush with lower surface  81  of male part  70 . In contrast to the first embodiment, the slopes of frustoconical portions  76  and  77  of corolla  74 , as well as those of frustoconical portions  54  (head) and  63  (ramp) are not uniform. 
     The (non-referenced) surfaces of female and male parts  60  and  70 , respectively, located opposite each other have complementary shoulders  65 ;  79 , the parts  60 ;  70  thus engaging in one another with a sliding fit. 
     The operation of the clasp during its opening and closure is equivalent to that described with reference to the first embodiment. It is therefore unnecessary to reconsider it in detail, except to mention the few particulars brought about by the differences in configuration. 
     Thus, abutment  56  of head  53 , adapted to bear on crown  75  of corolla  74 , has the effect of preventing that fingers  72  of male part  70  may open when the clasp is open. Such an opening might come about if an involuntary traction were applied to the end of the necklace (the heavier the necklace, the smaller a traction being sufficient), thereby pulling the head—in the absence of this safety provided by abutment  56 —into the interior of the fingers between which it would subsequently remain caught. Moreover, this safety allows to provide more resilient fingers and thus to improve the comfort of use without sacrificing the closure safety. 
     This abutment  56  also facilitates the introduction of male part  70  into female part  60  as it limits the opening of the collet, i.e. of the fingers. 
     The rounded shape of head  53  facilitates its introduction in female part  60 . 
     The difference in the opening angles of frustoconical parts  54  of head  53  and  76  of fingers  72  allow avoiding a possible build-up of dust particles that might practically “stick” these two elements  53 ,  72  and thereby make an opening difficult or even impossible. 
     The difference in the opening angles of frustoconical parts  77  of fingers  72  and of ramp  63  facilitates the contraction of fingers  72  during opening. 
     Shoulders  65 ;  79  prevent possible lateral twisting of the male and female parts and consequently any deformation and potentially resulting degradation of fingers  10 ;  72 . 
     Finally, milling  80  at the entrance of bore  73  provides a larger space for the connection of the end of a bracelet, necklace, or other object to stem  51  in this area. 
       FIGS. 7A and 7B  show the possibility of using the clasps for fastening jewels or other interchangeable objects to a chain. A cross  40  has been chosen in this example as it illustrates an original way of fastening a classic object to a chain or a wire. In the application according to  FIG. 7A , female parts  2 ;  60  of two clasps have been set in respective holes made in each of the two horizontal arms  41 ,  42  of the cross. Each one of cores  1 ;  50  is fastened to one of the two ends of a wire  13  or a fine chain. In  FIG. 7B , the female element  2 ;  60  of a single clasp is set in the upper part  46  of the vertical arm of a cross  45 . Stem  4 ;  51  of core  1 ;  50  is connected to the ends of two necklace portions  21 ,  22 , e.g. set in an orifice  20 , the other ends of these necklace portions being connected to a clasp according to one or another of the possible embodiments, e.g. a clasp  100 . If the user wants to change jewels, he or she only needs to open the clasp(s) and to attach e.g. a stone or a fantasy object that is also provided with one or two female clasp parts  2 ;  60 . 
       FIG. 8A  shows the attachment of a clasp to a wire that is sometimes used to manufacture a necklace. A wire  13  (using the same reference as that which designates the wire in  FIG. 7A ), at one end of which a retaining device  14  is mounted, is fastened to female part  2 ;  60  that is provided with a passage (not referenced). Device  14  may also be fastened to the latter. The other end of the wire is connected to the stem of core  1 ;  50 , e.g. set in an orifice  15  that is provided in the latter. The wire may be made of Nylon, of steel, or of another material of sufficient strength for this purpose. A cable can also be used. The connection between the wire and the stem of the core can be achieved with or without an intermediate member, e.g. by setting, driving in, cementing, welding, or screwing. 
       FIG. 8B  shows the attachment of the clasp to a chain. Conventional rings  16  and  17  are welded onto female part  2 ;  60  and stem  1 ;  50 , respectively. 
     Especially the external general shape of the clasp is advantageously cylindrical while it is understood that any other shape is conceivable, e.g. a prismatic one. 
     The clasp can be made from any adequate material such as gold, platinum, palladium, silver, stainless steel, aluminum, brass, while it is observed that a material having good elastic qualities will be chosen for the manufacture of fingers  10 ;  72 . 
     The embodiments described above illustrate some of the numerous possible applications of the invention by way of examples. They are by no means limiting.

Technology Classification (CPC): 8