Patent Publication Number: US-8984772-B2

Title: Footwear with shock adsorber

Description:
RELATED APPLICATIONS 
     This application is a 35 U.S.C. 371 national stage filing from International Application No. PCT/IT2007/000595 filed Aug. 29, 2007, the teachings of which are incorporated herein by reference. 
     The present invention concerns footwear with a protective component against impact, especially for sports activities such as a motocross boot referred to in the example. However, this invention is also applicable for different footwear such as sandals, slippers, boots etc. 
     In motorcycling, especially motocross, riders use reinforced boots so as to absorb possible impacts against the ground, other riders or, in case of a crash, against the same motorcycle. Such reinforcements can be provided both on the sides of the footwear, e.g. as plates made of non-deformable material, and on the bottom of the footwear, as thick soles and/or made of rigid material. In case of vertical falls, the rider&#39;s foot sole, especially the heel, is particularly subject to heavy impacts which, also due to the rigidity of the same reinforcements, lead to undesired bruises or fractures even. Similarly to motocross, even in other sports such as skateboard, the heel is subject to hard vertical impacts and hence attempts have been made to solve the problem by making footwear with specially shaped heels. 
     From U.S. Pat. No. 5,983,529, a sole is known which has, in the heel, an insert made up of shock-absorbing elements made of polyurethane or any other elastically deformable material, i.e. after the impact or crash the insert returns to the original shape or structure with a given time-constant. However, this kind of insert does not entirely dissipate the energy generated by the impact. 
     The main object of the invention consists in providing footwear with enhanced protection capacity against impacts or crashes. 
     This and other objects are achieved through a footwear able to protect the foot against the impact with an external body, such footwear comprising a protective component adapted to deform itself under pressure from the foot and/or external body during an impact, characterized in that the protective component has a permanently and irreversibly alterable structure capable of reacting to said pressure through a structural alteration which absorbs and at the same time dissipates the energy received during the impact. 
     Hence, an obvious advantage of this invention is that all the energy received by the protection component upon impact is dissipated, basically with zero energy returned. This implies clear benefit in terms of safety, given that the returned energy corresponds to a counter-impact against the foot. 
     The protective component may comprise a hollow structure adapted to yielding and deforming permanently under said pressure (generated by the collision). Thus the energy received during the collision is dissipated through the deformation of the protective component (and also in the form of heat). Given that the cavity yields and it has no pre-impact status memory, the returned energy is practically zero. 
     The effect of the hollow structure can be advantageously modulated in case the hollow structure comprises walls delimiting two or more void volumes. Therefore, in case of impact, sequential and progressive deformation of sub-cavities can be provided in order to modulate the energetic absorption efficiency of the protective component. 
     Thus, in this case, it is advantageous to structure the protective device with parallel yielding walls and to position them on planes basically perpendicular to a possible impact force directrix (for instance a pack of separated layers). Thus, gradually as the impact develops, a wall yields (and/or breaks) subsequently one after the other, and so on. 
     Therefore, making the protective component with a material able to permanently bend under said pressure might be very convenient. 
     Another option, suitable even in combination with the previous one, consists in making the protective component using fragile material capable of irreversibly breaking under said pressure. In this case, the energy received upon impact is directed to the breakage of the protective component (or its parts): such energy is not returned but entirely dissipated. 
     Advantageously, the protective component may consist of an insert which can be removably coupled with the footwear, such component being preferably housed in a seat within the footwear, positioned not in sight. Hence, once damaged by the crash, the insert can be replaced with a new one. Though internal, the seat may be accessible, for instance by making a wall thereof removable, in order to place or replace an insert therein. 
     In order to support the action of the protective component, even the seat holding it may have protective characteristics similar and/or different to the same protective device. An efficient solution consists in making at least one wall of the seat in a way to yield under said pressure. Therefore, even the walls of the seat can dissipate energy of the impact. 
     Advantageously, the protective component may be made using a unique material, a mix of materials or made up of various layers of different materials. In addition, a elastic member can be provided, coupled with the insert, having elastic behaviour, in a way to cushion light impacts. Hence, the braking of the protective component is saved only for cases of heavy impacts, thus avoiding continuous replacement. Obviously, the intervention thresholds of each part and/or material of the protective component are to be tested and/or designed depending on both on the end use, the footwear to be made and its topology. 
     Preferably, at least one wall of the seat has a thin strip adapted to bending under said pressure. This ensures that it is the strip, and not the foot, that impacts against the insert, thus guaranteeing higher safety conditions. 
     Optionally, there can be calibrated-rupture rigid connection points between the thin strip and at least one wall. Such connection points should be designed in a way to break under said pressure leaving the thin strip free to bend and abut against the insert. Hence the maximum load beyond which the strip should be released and thus the intervention threshold of the protective device can be defined. 
    
    
     
       Aspects and advantages of the present invention will appear more clearly from the following description, given as an illustrative example, with reference to the appended drawings in which: 
         FIG. 1  is an exploded view of a motorcycling boot according to the invention; 
         FIG. 2  is a schematic view of a longitudinal section (from heel to tip) of the boot of  FIG. 1  assembled; 
         FIG. 3  is a schematic view of a section of the boot of  FIG. 1  according to plane I-I in  FIG. 2 ; 
         FIG. 4  is a side section view of an insert according to the invention; 
         FIG. 5  is a view of the insert of  FIG. 4  at the beginning of an impact; 
         FIG. 6  is a view of the insert of  FIG. 5  at the end of an impact; 
         FIG. 7  is a view of the inner part of a variant of the boot without the insert; 
         FIG. 8  is a view of the inner part of a variant of the boot with the insert. 
     
    
    
     With reference to the figures,  10  indicates a boot (only partially showed), with a hull  30 , a tread  40  and an insert  20 , interposed between the first two. 
     Instead of having an upper coupled with a sole (possibly provided with a separate tread) as in traditional footwear, the boot  10  provides for the hull  30  to be monolithic and made as an integral single piece using rigid material such as an injected plastic material. Completed with appropriate covering elements (not shown) the boot  10  accommodates the rider&#39;s foot, possibly fitted into a textile footwear (see  FIG. 2 ). The hull  30  comprises an upper top part  36 , and a sole lower part  31 , into which a metal plate (or core)  51  can be embedded ( FIG. 3 ) with a reinforcing function. In the zone corresponding to a heel  32 , the sole  31  has a seat  33  receiving the insert  20 . The bottom wall  37  of the seat  33  is made so as to yield under pressure against it by the heel. In fact, it comprises a strip (or tongue)  50  capable of bending under said pressure. The strip  50  may comprise the whole or part of the plate  51  and it is permanently connected to the perimeter of the seat  33  through rigid connection peripheral points (or bridges)  38  (for instance obtainable during moulding). On the lower part of boot  10 , the tread  40  couples with the entire lower surface of the sole  31 , so as to also cover the insert  20  and hold it in the seat  33  ( FIG. 2 ). 
     The insert  20  is a substantially parallelepiped element, with rounded edges, made of material with fragile behaviour, i.e., when subject to an external force exceeding its breaking load it breaks without carrying out any plastic deformation. Such breakage ensures excellent dispersion of the impact energy. The material used should be chosen depending on the breaking load required, which will define the protective intervention threshold of the insert. 
     According to a different embodiment of the invention (see  FIGS. 4-6 ), an insert  120  may be made of ductile material and lacking elastic behaviour (and return) ( FIG. 4 ). It comprises an external parallelepiped case  80  which defines an internal cavity  82 . Such cavity is divided into sub-cavities  84   a ,  84   b ,  84   c  by two yielding walls  86   a ,  86   b . An impact towards direction F (see  FIGS. 5 and 6 ) first causes wall  86   a , then wall  86   b  to collapse (and/or break) sequentially. It is clear how the partition into void volumes  84   a,b,c  and the mechanical characteristics of the walls  86   a ,  86   b  allow to determine the behaviour of the insert  120  during the impact, thereby modulating its intervention thresholds and its responses to the impact. 
     According to a further embodiment of the invention, (see  FIGS. 7 ,  8 ) a hull  230  of a boot  210  comprises an upper top part  236 —, and a sole lower part  231 . A seat  233  is obtained in a region of the heel  232  of the sole  231  and it is defined by a peripheral edge  235  and a flexible, floating strip  250 . 
     Similarly to the first embodiment, an insert  220  ( FIG. 8 ) is accommodated in the seat  233 , blocked on the upper side by the strip  250  and on the lower side by a tread not illustrated in the figures. 
     There are three teeth  239 , protruding from the rear portion of the peripheral edge  235 , adapted to holding the insert  220  permanently in the seat  233 . 
     In opposite position to the protruding teeth  239 , there are two cuts  260  running through the entire thickness of the sole  231 , extending parallel along the length of the strip  250 . The cuts  260  guarantee greater flexibility of the strip  250 , and also of a part of the sole  231 . 
     A boot according to the invention is very useful for sports activities such as motocross, where the rider is often subject to vertical falls leading to impacts against the heels. By impacting against the inserts  20 ,  120 ,  220 , the heel breaks or deforms the inserts. This leads to the substantially complete absorption and dissipation of the energy generated during the collision, thereby reducing the rider&#39;s risks of injury or at least reducing risks of heel fracture. The heel  32 ,  232  is capable of elastically cushioning light impacts thanks to the oscillating strip  50 ,  250 , while impacts of grater magnitude are absorbed by the intervention of the insert  20 , 120 , 220 . 
     In addition, in the first and second embodiments, the energy developed may be dissipated even through breakage of the connection points  38 . In fact, should the amount of the force exerted by the heel on the insert  20 ,  120  exceeds the static reaction of the points  38 , the latter break dissipating energy irreversibly. Before and/or after such breakage, the strip  50  can be made in a way that it may be able to oscillate, thus cushioning the impact (and the points  38  may be slightly elastic allowing the strip to bend slightly). 
     Functionally or conceptually equivalent modifications and variants are possible and can be provided within the scope of the invention as defined by the subsequent claims. For instance, according to the invention, one or more protection devices can be positioned not only on the heel region but also in other parts of the footwear.