Patent Publication Number: US-6219889-B1

Title: Adjustable clasp device

Description:
DESCRIPTION 
     The present invention relates to an adjustable clasp device comprising a retainer body provided with an elongate cavity for sliding of a strap having saw teeth, in which the retainer body and the strap are intended to be connected with associated elements to be joined together, the retainer body including a generally non-deformable main portion from which extends a flexible tongue provided with pawl means projecting into the said cavity and engageable with the teeth of the strap to prevent relative sliding of the retainer body and the strap, and at least one resilient wing arranged alongside the flexible tongue and operable under pressure to disengage the pawl means from the teeth of the strap, the retainer body having first guide members at the said main portion and second guide members in proximity with the end of the retainer body opposite its main portion, such guide members being intended to maintain the strap in a position in which its teeth are close to the pawl means. 
     In adjustable clasp devices of the known type defined above, the retainer body has a rigid structure with an intermediate part from which the said flexible tongue with the pawl means projects, and a pair of resilient wings. The rigid structure includes at both axial ends, that is on opposite parts with respect to the intermediate part with the flexible tongue and the resilient wings, guide members which surround the strap to retain it in a position close to the pawl means of the flexible tongue. 
     Because of the structure of the retainer body, in particular due to the presence of rigid guide means at both axial ends of the body, known adjustable clasp devices are relatively long in the axial direction of the strap such that they are not well adapted to be used in applications in which a compact form of the retainer body is required. 
     For the purpose of overcoming this disadvantage, the subject of the present invention is a clasp device of the type indicated above, characterised in that the second guide members comprise an abutment portion which extends from the said at least one resilient wing at its end substantially opposite the main portion of the retainer body. 
     Thanks to this arrangement the retainer body of the clasp device according to the invention can be formed with a non-deformable main portion of limited axial extent, from which a plurality of flexible elements project which also define the second guide means for the strap, such that the clasp device can be formed in such a way as to be significantly more compact than known similar devices. 
     The invention also comprehends a headband for headgear such as a helmet, characterised in that it includes a tension adjustment fitting including at least one adjustable clasp device of the above-indicated type. 
    
    
     Further characteristics and advantages of the invention will become more apparent from reading the following detailed description, provided purely by way of non-limitative example and with reference to the attached drawings, in which: 
     FIG. 1 is a schematic perspective view of an adjustable clasp device according to the invention; 
     FIG. 2 is an elevational view seen in the direction of the arrow II of FIG. 1; 
     FIG. 3 is a sectioned elevational view taken on the line III—III of FIG. 2; 
     FIG. 4 is an elevational view seen in the direction of the arrow IV of FIG. 1, in which the strap is indicated in broken outline; 
     FIG. 5 is a front elevational view seen from the direction of the arrow V of FIG. 4; and 
     FIG. 6 is a schematic upper elevational view of an adjustment fitting usable in a headband for headgear. 
    
    
     First, with reference to FIGS. 1 to  5 , an adjustable clasp device is generally indicated with reference numeral  1 . An adjustment device of this type can be used, for example, for clasping any type of strap or a closure edge of a garment, for example a footwear. 
     The device  1  comprises a retainer body  3 , normally made in one piece of moulded plastics material, preferably of a plastics material including a mineral filler such as glass fibre to make it sufficiently rigid. 
     The body  3  has an elongate longitudinal cavity  5  in which a strap  7  is slidably arranged, which is also normally made of plastics material, on one side of which are formed a series of saw teeth  9 . The body  3  and the strap  7  are intended to be connected each with an associated element to be joined together (not illustrated in the drawings). For this purpose, in the body  3  there is provided a cylindrical seat  11  transversely of the axis of the strap  7  for engagement of the end of such an element, for example in the form of a strip, having a corresponding cylindrical terminal portion. 
     The body  3  is provided with a substantially non-deformable main portion  13 , also traversed by the cavity  5 . From the portion  13  extends a tongue  15  at least of limited flexibility and provided, on the opposite end from the portion  13 , with a plurality of teeth  16  serving as pawls for engagement of the teeth  9  of the strap  7 . Preferably there are four teeth  16 . Conveniently, the tongue  15  is provided on its inner surface facing towards the strap  7  with perimetral reinforcing ribs  15   a.    
     From the tongue  15  extend, on the same side as the teeth  16 , a pair of blade-like projections  18  arranged parallel to one another and to the axis of the strap  7  and separated by a distance equal to the width of the strap  7 , for the purpose of constituting a containment guide for the relative axial movement of the strap with respect to the body  3  and to maintain the strap  7  in a position in which its teeth  9  face the teeth  16  so as to encourage correct engagement of these teeth with one another. 
     The part of the cavity  5  formed in the main portion  13  is delimited on the opposite side from the tongue  15  by a pair of brackets  21  which extend from the portion  13 , between which brackets is defined a V-shape space the vertex of which faces away from the tongue  15 , the purpose of which will be explained hereinafter. 
     From the portion  13 , alongside the tongue  15 , also project a pair of resilient wings  23  preferably having a form tapered towards the end opposite the main portion  13 , that is in correspondence with their flexing region, in such a way as substantially to prevent them from being able to be subject to appreciable torsional deformations with respect to the main portion  13 . 
     At the end of each wing  23  opposite the portion  13  a blade-like abutment portion  25  projects towards the general axis of the strap  9  in such a way as to lie against at least the side of the strap  7  opposite the tongue  15 , to retain the strap  7  close to the teeth  16  of the tongue  15 . 
     From the end of each of the wings  23  there also extends a counter element  27 , substantially parallel to the associated portion  25 , and shorter than it, intended to interfere by means of its free end with an inclined lateral surface  29  formed alongside the teeth  16  in such a way that, following a pressure exerted from the outside onto the wings  23  and their consequent deformation towards the tongue  15 , the counter elements  27  cause separation of the tongue  15 , and therefore of its teeth  16 , from the position of engagement with the teeth  9  of the strap  7 . 
     Thanks to the structure of the body  3  according to the invention, which in particular has a relatively small main portion  13  from which extend only cantilevered parts, in particular the tongue  15  and the two wings  23 , the body  3  is very compact and can be made with the use of less material whilst still being able to ensure an extremely effective grip on the teeth  9  of the strap  7 . 
     With reference to FIG. 6, a pair of clasp devices  1  can be used in a headband for headgear such as a helmet. In this case, the headband (not illustrated entirely in the figures in that its general structure is known per se) has its opposite ends each connected to a respective retainer body  3  by the insertion of an associated cylindrical end piece into a corresponding seat  11 . 
     The retainer bodies  3  are mounted in opposite positions from one another in such a way as both to be slidable along a common strap  7  of arcuate form connected by means of bridges  33  to a shaped structure  31  in such a way as to be able to rest on the occipital region of the head. 
     In particular, the strap  7  has a first series of teeth  9   a  and a second series of teeth  9   b , both of sawtooth type, with opposite inclinations in such a way that by bringing the retainer bodies  13  towards one another it is possible to tension the headband by causing relative approach of both its ends, whilst when they are separated from one another the headband become enlarged. 
     The bridges  33  arranged close to the axial ends of the structure  31  have a strut part joined to the face of the straps  7  opposite that which carries the teeth  9   a ,  9   b . The V-shape space of each body  3  has a width slightly less than the width of this strut part so that when the body  3  is fitted onto the associated part of the strap  7  the brackets  21  deform slightly, thanks to their entrance region constituted by the V-shape, thus allowing the strut part to be formed into the V-shape space, but opposing the passage of the strut part when the body  3  moves along the strap  7  in the opposite direction, thereby preventing accidental separation of each of the bodies  3  from the strap  7 .