Abstract:
A buckle includes a snap coupling mechanism including a locking element pivotable between a locked and an unlocked position for engaging and disengaging two tongues, respectively; a release button movable between a raised position and a lowered position corresponding to the locked and unlocked positions, respectively; a spring tending to keep the release button in the raised position; and two sliders opposing the insertion of the tongues. The sliders are configured to come between a body of the buckle and the locking element, when the locking element is moved into the unlocked position, so as to prevent the locking element from moving from the unlocked position to the locked position. The release button is connected to the locking element so that when the release button is pressed, the locking element moves into the unlocked position, whereas when the release button is released, the locking element moves into the locked position.

Description:
This application claims benefit of Serial No. TO2011A001122, filed 7 Dec. 2011 in Italy and which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications. 
     BACKGROUND OF THE INVENTION 
     The present invention relates in general to a fastening device for restraint belts, particularly for car safety seats for children, and more in particular to a buckle for such a fastening device. 
     The restraint belts used on car safety seats for children typically comprise three branches, which can be releasably connected to each other by means of a fastening device comprising a buckle attached to the free end of one of the branches and two tongue-like coupling elements (hereinafter simply referred to as “tongues”), which are attached to the other two branches and are intended to be inserted into an inner body (preferably made of metal) of the buckle along a direction of insertion and to be locked therein to ensure that the belts are fastened around the trunk of the child sitting in the seat. 
     More specifically, the present invention relates to a buckle provided with a snap coupling mechanism adapted to releasably couple the two tongues to the inner body, the snap coupling mechanism comprising: 
     a locking element supported by the inner body so as to be pivotable about an axis perpendicular to the direction of insertion between a lock position, in which it engages the tongues and thus keeps them restrained in the inner body, and an unlock position, in which it disengages the tongues thereby making them free to be ejected from or pulled out of the inner body, 
     a release button which is operatively connected to the locking element and can be moved by the user along a direction perpendicular both to the direction of insertion of the tongues and to the pivot axis of the locking element to cause the locking element to move from the lock position to the unlock position, thereby allowing the tongues to be ejected from the inner body, and 
     a pair of sliders or ejectors mounted in the inner body so as to be movable along respective directions parallel to the direction of insertion of the tongues, the sliders being urged by respective springs in order to apply on the tongues a resilient force tending to oppose the insertion of the tongues into the inner body and to make the ejection of the tongues from the inner body, when the locking element is in the unlock position, easier. In a buckle of the above-specified kind, the release button is normally kept by a spring in a raised rest position, i.e. in a rest position facing outwardly of the buckle. In order to uncouple the tongues from the buckle, the user must press the release button against the resilient force applied by the associated spring. Once released, the release button gets back into its rest position under the action of the associated spring. When the tongues are inserted into the inner body to fasten the restraint belts, the release button remains in the rest position under the action of the associated spring, independently of the tongues having been correctly inserted into the inner body and engaged by the locking element. This is particularly critical for buckles to be sold on the US market, since the regulations currently in force in the United States provide for the possibility to insert one tongue at a time into the buckle. It may therefore happen that a first tongue is correctly inserted into and coupled to the buckle and that the second tongue is inserted into the buckle but is not correctly locked by the locking element without this being immediately and unambiguously realized by the user. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a buckle of the above-specified kind, which is able to make the user immediately realize whether the tongues are correctly locked therein. 
     This object is fully achieved according to the present invention by virtue of a buckle for restraint belts, particularly for car safety seats for children. 
     In short, the invention is based on the idea of providing a buckle of the above-identified kind, wherein 
     each slider is configured to come between the inner body and the locking element, when this latter is moved into the unlock position, so as to prevent the locking element from moving into the lock position until it is urged back, against the resilient action of the respective spring, by the respective tongue when this latter is inserted into the buckle, and wherein 
     the release button and the locking element are connected to each other in such a manner that when the release button is pressed the locking element moves away from the inner body into the unlock position, whereas when the release button is released, and hence gets back into the rest position due to the resilient action applied thereon by the associated spring, the locking element is pulled by the release button so as to move towards the inner body and take the lock position. 
     By virtue of such a configuration, as long as the tongues are not inserted into the buckle to such an extent as to prevent the sliders from keeping the locking element in the unlock position, the locking element remains in the unlock position and hence the release button, which moves as a single body with the locking element, remains in the pressed or lowered position. The release button has thus two stable operating positions, namely a first position corresponding to the aforesaid rest position (or raised position), that the release button takes when the locking element is in the lock position, and a second position (or lowered position) that the release button takes when the locking element is in the unlock position. Accordingly, as long as the tongues are not correctly inserted into the inner body and engaged by the locking element, the locking element is kept by the slider(s) in the unlock position and hence the release button is kept in the aforesaid second position. The user is therefore in the condition to immediately and unambiguously realize, seeing that the release button is still lowered, that the tongues are not both correctly locked in the buckle. 
     According to an embodiment of the invention, in order to allow the user to realize in a still more immediate and clear way whether the tongues are correctly locked in the inner body of the buckle, the buckle comprises signalling means associated to the release button to provide the user with a visual indication associated to at least one of the two stable positions of the release button, showing for instance a green-coloured symbol when the release button is in the raised position corresponding to the tongues being correctly locked in the inner body of the buckle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention will become apparent from the following detailed description, given purely by way of non-limiting example with reference to the appended drawings, in which: 
         FIGS. 1 and 2  are exploded perspective views, from above and from below, respectively, of a fastening device for three-branch restraint belts, particularly for car safety seats for children, according to a preferred embodiment of the present invention; 
         FIGS. 3 and 4  are a perspective view and a side elevational view, respectively, of the snap coupling mechanism and of the inner body of the buckle of the fastening device of  FIGS. 1 and 2  in the open position, i.e. in the unlock position of the locking element of that mechanism; 
         FIGS. 5 and 6  are a perspective view and a side elevational view, respectively, of the snap coupling mechanism and of the inner body of the buckle of the fastening device of  FIGS. 1 and 2  in the closed position, i.e. in the lock position of the locking element of that mechanism; and 
         FIG. 7  is a perspective view of the assembly formed by the release button and by the locking element of the snap coupling mechanism of the buckle of the fastening device of  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description and claims, terms such as “upper” and lower” are to be intended as referring to the orientation of the fastening device as shown in  FIG. 1 , where the release button of the buckle is visible from above. 
     With reference first to  FIGS. 1 and 2 , a fastening device for three-branch restraint belts, particularly for car safety seats for children, is generally indicated  10  and basically comprises a buckle  12  intended to be attached to the free end of a belt branch (not shown) and a pair of tongue-like elements  14  (hereinafter simply referred to as tongues) intended to be attached each to a respective belt branch (also not shown) and to be inserted into the buckle  12  to be locked therein in order to ensure that the belts are fastened around the trunk of the child sitting in the seat. 
     Each tongue  14  preferably includes a metal core made for instance as a plate-like element integrally forming a stem portion  16 , which is adapted to be inserted into the buckle  12  along a direction of insertion x and locked therein, and an attachment portion (not shown), in which a slot  18  is provided for attachment of the tongue to the respective belt branch. The stem portion  16  of each tongue  14  also forms at its free end a coupling tooth  20 , which extends perpendicular to the direction of insertion x. The metal core is fully covered by a layer of plastic material or rubber, which is advantageously obtained by overmoulding of that material over the metal core. 
     The buckle  12  includes an inner body  22  preferably made as a single piece of sheet metal obtained by blanking and folding and an outer shell preferably consisting in two upper and lower half-shells  24  and  26 , respectively, which are firmly connected to each other so as to enclose the inner body  22 . The half-shells  24  and  26  are preferably made of plastic material. 
     According to the illustrated embodiment, the inner body  22  includes an upper plate  28  and a lower plate  30  which extend parallel to and spaced from each other and are connected at a first end by a connecting portion  32  which extends substantially perpendicular to the two plates  28  and  30 . The two plates  28  and  30  form at the opposite end respective attachment extensions  34 , each having a slot  36  for fixing the inner body  22 , and therefore the whole buckle  12 , to the respective belt branch. The two plates  28  and  30  are also connected to each other in the zone of the attachment extensions  34 , for instance by welding, gluing or riveting. The connecting portion  32  has a through opening  38 , through which the stem portions  16  of the tongues  14 , along with the respective coupling teeth  20 , are inserted into the inner body  22 . The upper plate  28  and the lower plate  30  have each a pair of longitudinal slits, indicated  40  and  42 , respectively, i.e. a pair of slits which extend parallel to the direction of insertion x. The longitudinal slits  40  of the upper plate  28  are aligned to the longitudinal slits  42  of the lower plate  30  and preferably have the same length as these latter. The buckle  12  further comprises a snap coupling mechanism for releasably connecting the two tongues  14  to the inner body  22 . 
     First of all, the snap coupling mechanism comprises a locking element  44  made as a plate-like element, preferably of metal, in particular of steel. The locking element  44  forms, at its end facing in the assembled condition towards the slot  36  of the inner body  22  (belt-side end), a hinge tab  46  having a goose-neck shape and engaging in a first transverse slit  48  (i.e. a first slit extending perpendicular to the direction of insertion x) of the lower plate  30  of the inner body  22  to allow the locking element  44  to pivot relative to the inner body  22  about a transverse pivot axis y. Moreover, by virtue of the use of a single hinge tab  46  placed in the middle of the locking element  44 , this latter can pivot relative to the inner body  22  also about an axis coinciding with the direction of insertion x to allow the insertion of only one tongue at a time into the inner body  22 . At the opposite end, i.e. at the end facing in the assembled condition towards the opening  38  (tongue-side end), the locking element  44  forms a stop tab  50  which extends perpendicular to the middle plane of the locking element  44  and has the function of restraining the coupling teeth  20  of the tongues  14  in the direction of insertion x. Preferably, both the hinge tab  46  and the stop tab  50  are formed as a single piece with the locking element  44 . The locking element  44  has also a pair of longitudinal slits  52 , which in the assembled condition are aligned each to a respective longitudinal slit  40  of the upper plate  28  and to a respective longitudinal slit  42  of the lower plate  30  of the inner body  22 . The length of the longitudinal slits  52  of the locking element  44  is smaller than that of the longitudinal slits  42  of the lower plate  30  of the inner body  22 . As shown in  FIGS. 3 to 6 , the locking element  44  is able to pivot relative to the inner body  22  about the aforesaid pivot axis y between a lock position ( FIGS. 5 and 6 ), in which it engages the coupling teeth  20  of the tongues  14 , thereby keeping these latter restrained in the inner body  22 , and an unlock position ( FIGS. 3 and 4 ), in which it disengages the tongues  14  and hence make them free to be ejected from or pulled out of the inner body  22 . In the lock position, the locking element  44  abuts against the outer face of the lower plate  30  of the inner body  22  and the stop tab  50  enters the inner body  22  passing through a second transverse slit  56  provided in the lower plate  30  of the inner body  22 . In this position, the stop tab  50  forms an abutment surface which, cooperating with the coupling teeth  20  of the tongues  14 , prevents these latter from being released from the buckle  12 . In the unlock position, the locking element  44  is inclined to the lower plate  30  about the pivot axis y by an angle such that the stop tab  50  does not enter the inner body  22  and hence does not engage the coupling teeth  20  of the tongues  14 . The tongues  14  can thus be released from the buckle  12 . 
     The snap coupling mechanism further comprises a pair of sliders  58  having the function of opposing the insertion of the tongues  14  into the buckle  12  when the belts are fastened and of making the ejection of the tongues  14  from the buckle  12  easier when the belts are unfastened. Each slider  58  comprises a middle portion  60 , which is received between the two plates  28  and  30  of the inner body  22  and has a width larger than that of the longitudinal slits  40  and  42  provided in those plates, and a pair of upper and lower guide projections  62  and  64 , respectively, which project from opposite sides of the middle portion  60  and slidably engage in the longitudinal slits  40  and  42  provided in the plates  28  and  30  of the inner body  22 . The guide projection  64  (lower guide projection) of each slider  58  has a height such that it projects downwards beyond the outer face of the lower plate  30  of the inner body  22  to slidably engage in the respective longitudinal slit  52  of the locking element  44 . A respective spring  66  is associated to each slider  58  and is made for instance as a cylindrical helical spring, which rests at one end (tongue-side end) against the slider  58  and at the opposite end (belt-side end) against a respective abutment surface  68  formed for instance by a respective tab which is bent so as to project towards the inside of the inner body  22  from the upper plate  28  or from the lower plate  30 . Each spring  66  applies on the respective slider  58  a resilient force which is directed parallel to the direction of insertion x and tends to urge the slider  58  towards the opening  38  of the inner body  22  (i.e. towards the tongues  14 ). When the tongues  14  are inserted into the buckle  12 , the coupling teeth  20  press each on a respective slider  58 , thereby causing it to move back and at the same time the respective spring  66  to be compressed. In this phase, therefore, the sliders  58  and the respective springs  66  apply on the tongues  14  a resilient force tending to oppose the insertion of these latter into the buckle  12 . On the contrary, during ejection of the tongues  14  the sliders  58  and the respective springs  66  apply on the tongues  14  a resilient force tending to make the ejection of these latter from the buckle  12  easier. 
     The sliders  58  also have the function of keeping the locking element  44  stably in the above-described unlock position, once this latter has been moved in that position. When the locking element  44  is in the lock position ( FIGS. 5 and 6 ), the guide projection  64  (lower guide projection) of each slider  58  slidably engages in the respective longitudinal slit  52  of the locking element  44 . When, on the other hand, the locking element  44  is moved into the unlock position ( FIGS. 3 and 4 ), the guide projection  64  of each slider  58  disengages from the respective longitudinal slit  52  of the locking element  44  and comes into abutment against a “solid” portion of the locking element itself, thereby preventing the locking element from moving towards the lock position. Only when the tongues  14  are inserted into the inner body  22  and cause the sliders  58  to move backwards, thereby bringing the respective guide projections  64  back inside the respective longitudinal slits  52 , the locking element  44  can move towards the lock position. The two lock and unlock positions of the locking element  44  are therefore stable operating positions. 
     The snap coupling mechanism further comprises a release button  70  received in a cavity  72  provided in the upper half-shell  24  of the outer shell of the buckle  12  so as to be slidable along a direction z perpendicular to the plates  28  and  30  of the inner body  22  (i.e. along a vertical direction, according to the point of view of one looking at  FIGS. 4 and 6 ). The release button  70  and the locking element  44  are therefore arranged on opposite sides of the inner body  22 . The release button  70  is connected to the locking element  44  in such a manner that its movement along the direction z brings about a pivoting movement of the locking element  44  about the pivot axis y. More specifically, the release button  70  comprises an upper plate portion  74  (hereinafter simply referred to as plate), on which the user can apply a pressure with a finger, and a leg  76  which extends vertically downwards from the plate  74  (preferably from a middle point of the plate  74 ) and, in the mounted condition, passes through both the plates  28  and  30  of the inner body  22  and engages at its lower end, for instance by means of a bayonet coupling, in a slot  78  provided in the locking element  44  ( FIG. 7 ). As shown in  FIGS. 3 to 6 , the release button  70  is normally kept, due to the resilient force applied by a spring  80 , in a raised position. In this position, the locking element  44  is in contact with the lower plate  30  of the inner body  22  and is therefore in the lock position. If the release button  70  is pressed by the user against the resilient force applied by the spring  80 , the locking element  44  is moved away from the lower plate  30  of the inner body  22  and pivots about the pivot axis y. By virtue of suitable travel limiting means, described in detail further on, the downward movement of the release button  70  is limited to a lower end-of-travel position (hereinafter simply referred to as lowered position) corresponding to the unlock position of the locking element  44 . The lock position of the locking element  44 , i.e. the position in which the tongues  14  are locked in the buckle  12 , corresponds therefore to the raised position of the release button  70 , whereas the unlock position of the locking element  44 , i.e. the position in which the tongues  14  are no more engaged by the locking element  44  and can then be ejected from the buckle  12  by means of the sliders  58 , corresponds to the lowered position of the release button  70 . The spring  80  is preferably made as a cylindrical helical spring wound around the leg  76  of the release button  70  and rests at the one end (lower end) against the upper plate  28  of the inner body  22  and at the other end (upper end) against the plate  74  of the release button  70 . The aforesaid travel limiting means, which are adapted to limit the downward movement of the release button  70  and hence define the lowered position thereof, are formed in the illustrated embodiment by four legs  82  which are shorter than the leg  76 , extend also vertically downwards from the plate  74  of the release button  70  and have an outer diameter, or width, larger than the width of the longitudinal slits  40  in the upper plate  28  of the inner body  22 . An extension  84  having a diameter (or width) smaller than the width of the longitudinal slits  40  and than the diameter (or width) of the remaining leg portion extends downwards from the free end of each of the four legs  82 . Each leg  82  forms therefore, around the respective extension  84 , an abutment surface  86  parallel to the upper plate  40  of the inner body  22 . In this way, when the release button  44  is moved downwards from the raised position, the extensions  84  of the legs  82  enter the longitudinal slits  40  until the abutment surfaces  86  come into abutment against the upper plate  40  of the inner body  22 , thereby preventing the release button  44  from moving further downwards. 
     By virtue of the configuration described above, the release button of the buckle of the fastening device of the present invention has two stable operating positions which are well separate from each other and can thus be easily and unambiguously identified by the user, namely a raised position corresponding to the fastened condition of the belts (tongues correctly inserted into the buckle and locked therein) and a lowered position corresponding to the unfastened condition of the belts (tongues not locked in the buckle). Therefore, as long as the tongues are not correctly inserted into the inner body of the buckle and engaged by the locking element, the locking element is kept by the sliders in the unlock position and the release button is thus kept in the lowered position. The user thus realizes, seeing that the release button is still lowered, that the tongues are not both correctly locked in the buckle. 
     Naturally, the principle of the invention remaining unchanged, the embodiments and the constructional details may vary widely from those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims. 
     The buckle as described and illustrated in the present application is conceived to meet the US regulations, which provide for the possibility to insert only one tongue at a time into the inner body of the buckle. As is clear in the light of the preceding description, the insertion of only one tongue into the inner body of the buckle simply causes the locking element to pivot about a pivot axis directed along the direction of insertion x, but is not sufficient to cause the locking element to move from the unlock position into the lock position, and hence to move the release button from the lowered position into the raised position. The release button remains therefore in the lowered position, which warns the user of the unfastened condition of the belts. The buckle of the present invention can however be easily adapted also to the European regulations, which require the simultaneous insertion of both the tongues into the inner body of the buckle. For this purpose, it is in fact sufficient to use a locking element having two hinge tabs placed on opposite sides of the direction of insertion, instead of only one hinge tab placed in the middle, whereby the locking element is prevented from pivoting about an axis directed along the direction of insertion.