Patent Publication Number: US-6910287-B2

Title: Shoe midsole

Description:
TECHNICAL FIELD 
     This application is a 371 of PCT/DK01/00527 filed 8 Aug., 2001. The invention relates to a shoe midsole for shoes affording exceptional walking comfort, eg hiking shoes, said shoe midsole provided with a shock absorber in its heel zone and at least one bead behind and adjacent the heel zone, said bead completely or partially following a U-shape and acting as side support to the heel of the shoe wearer. 
     BACKGROUND ART 
     It is known to produce shoe soles with heel zones provided with a shock absorber. Such shock absorbers may be provided in many different ways, eg by means of springs or air cushions. It is also known to provide a substantially U-shaped side support bead in such a shoe sole, said support bead being arranged behind and abutting the heel of the shoe wearer&#39;s to provide support. This sole is, however, not quite satisfactory, as it does not provide adequate flexibility during a shoe wearer&#39;s walking motion and does not conform adequately to the contour of the wearer&#39;s foot during walking. Thus, the sole does not enable the manufacture of a shoe, which is comfortable to use for walking and in particular for hiking. 
     BRIEF DESCRIPTIONS OF THE INVENTION 
     The object of the invention is to provide a shoe midsole of the above type providing a high degree of flexibility during motion as well as more readily than known soles conforming to the organic tissue of the wearer&#39;s foot in a motion cycle such that the shoe of which the shoe midsole is to form part is particularly comfortable to use for walking. 
     The shoe midsole according to the invention is characterised in that it is flexible about at least two slightly curved bending lines, which are inclined relative to the longitudinal axis of the sole, said lines being defined by channels or grooves in the sole material and not intersecting each other, the cavities of the bending lines facing opposite of each other, and in that a particularly elastic portion of a hand-like shape forming part of the shoe midsole with at least two finger-shaped zones pointing at the toe end of the sole. As a result a particularly comfortable finished shoe may be obtained, as the complete sole (consisting of the insole, the midsole and the outsole) provides the wearer in motion with the feeling that the sole accurately conforms to the foot of the wearer, the midsole yielding at the curved bending lines, in addition to absorbing shock at the heel and providing side support to the heel of the wearer. In addition hereto the finger-shaped zones may yield differently under the bones of the wearer&#39;s foot, the wearer&#39;s toes and associated bones of the foot must be able to move slightly differently from each other. The reason why it is important that the finger-shaped zone may move dependent on the bones of the wearer&#39;s foot is that the said toes with bones of the foot otherwise would be subjected to considerable heat-generating frictional forces. 
     According to the invention the bending lines may each have a varying radius of curvature, the radius of curvature preferably being longest at the centre of the bending lines and shortest at the end of the lines, and the front end of each bending line may slope “upwards” towards the side at which with the hallux zone of the sole is situated. The shoe of which the finished sole is to form part is thus particularly comfortable. 
     Furthermore according to the invention the elastic portion may form part of the upper face of the midsole and preferably be made of a comparatively hard ethylene vinyl acetate (EVA), while the rest of the sole may be made of a comparatively soft EVA. The wearer of the completed shoe sole will then feel that the elastic portion “conforms” to organic tissue of the foot in motion such that less friction arises between said portion and said tissue. Consequently the shoe will not feel uncomfortably hot, but is comfortable to walk in. 
     According to the invention the elastic portion may form part of the midsole, whereby the finished sole becomes particularly comfortable to use. When a person for instance ascends an inclined surface, he exerts a higher compressive force on the portion of the foot corresponding to the hallux. However, due to its elasticity said elastic portion induces a “push-off” effect in the foot at the start of a step. When a wearer for instance descends an inclined surface, he exerts a higher compressive force on the little toe side of the sole (in the same way as a skier attempting to stop his skies by letting the tips of the skies point towards each other (to plough)). The finger-shaped zone may provide the wearer with an extra push during the last part of a step when descending the inclined surface. 
     According to the invention the midsole may be provided with at least one area with corrugation-like projections on its lower face and within the elastic portion. As a result the finished sole possesses a particularly high flexibility in the longitudinal direction and stability in the transverse direction. 
     Furthermore according to the invention the corrugations may be substantially parallel in each area, whereby the flexibility also is enhanced. 
     According to the invention adjacent the heel zone of the midsole an area containing a number of, preferably at least three, parallel corrugations substantially perpendicular to the longitudinal axis of the sole may be provided. This embodiment turned out to be particularly advantageous. 
     According to the invention a system of substantially parallel corrugations optionally substantially following curved lines may be provided in the areas within the finger-shaped zones and/or in the areas outside the area of the ball of the foot in the elastic portion. This embodiment of the sole has also proved to provide the finished sole with a high flexibility. 
     Moreover according to the invention with the longitudinal axis of the midsole the corrugations within each finger zone may form an angle v 1  of approximately 70-80°, at the finger adjacent the hallux zone of the sole and an angle v 2  of approximately 40-60°, at the finger adjacent the little toe zone of said sole, whereby the midsole and thus the finished sole possesses a particularly foot-friendly flexibility. 
     According to the invention a part of the particularly elastic portion may extend substantially from the centre of the heel zone to a position past the zone of the ball of the foot, but ends prior to the toe zones of the midsole and optionally extends upwards in one or both of the lateral parts of the midsole at the instep of the midsole. As a result an enhance stability of the foot is obtained. 
     The invention further relates to a shoe sole comprising the shoe midsole described in claims  1 - 10 , an upper insole, a sock of the sandwich-type provided overtop the insole, and an outsole provided beneath the midsole. This shoe sole is characterised in that a comparatively smooth portion, preferably made of leather or plastics, is provided in the hallux zone of the sock and in at least a portion of the zone of the ball of the foot, whereby the finished shoe sole affords the wearer a particularly high comfort during walking. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in detail below with reference to the accompanying drawings, in which 
         FIG. 1  is a top view of an embodiment of the sole according to the invention, 
         FIG. 2  is a bottom view of a second embodiment of the sole, 
         FIG. 3  is a sectional view of an embodiment along the line III—III in  FIG. 1 , 
         FIG. 4  is a bottom view of an embodiment of the sole provided with corrugations, 
         FIG. 5  is a sectional view along the line V—V in  FIG. 4 , 
         FIG. 6  is a side view of an embodiment of the sole, in which the particularly elastic portion slopes upwardly at the instep zone thereof, and 
         FIG. 7  is a top view of a sock to be arranged atop an insole provided atop the midsole according to the invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The shoe midsole shown in  FIG. 1  affording an exceptionally comfortable walking experience and eg suitable for manufacturing hiking shoes, is denoted as a whole by the reference numeral  1 . In its heel zone  4  the sole is provided with a shock absorber  6  and at least one bead  8  behind and adjacent the heel zone, said bead completely or partially following a U-shape and acting as side support for the heel of the shoe wearer. The bead is only indicated by means of a dotted line. The shock absorber is preferably pneumatic or of a particularly shock-absorbing sole material. 
     The shoe midsole is flexible about two slightly curved bending lines  12 , 14  which are inclined relative to the longitudinal axis  10  of the sole, said bending lines being defined by channels or grooves in the sole material, confer FIG.  3 . The bending lines  12 , 14  do not intersect each other and their cavities face away from each other. Each of the convex sides  12   a ,  14   a  faces towards the other. Each of the bending lines  12 , 14  may have a varying radius of curvature; it is usually shortest at the centre of the bending line and longest towards the end of the line. The front end  14 , 12   a  of the bending lines may slope “upwards” towards the side at which the hallux zone  13  of the midsole is present, as shown in FIG.  1 . 
     The midsole has a particularly elastic portion  16  of a hand-like shape (shown dotted) with at least two finger-shaped zones pointing towards the toe end  30  of the sole. In the present case three such finger-shaped zones  18   a ,  18   b  and  18   c  are shown. As shown in  FIG. 1  the elastic portion  16 , which has been moulded or inserted into the remaining portion of the midsole material, forms part of the upper face of the midsole, but may be completely circumscribed by the remaining midsole material. The elastic portion  16  is preferably made of a comparatively hard ethylene vinyl acetate (EVA), while the rest of the sole is made of a comparatively soft EVA. 
     The elastic portion  16  may also be part of the lower face of the midsole, as shown in FIG.  2 . 
     On its lower face and within the elastic portion  16  the midsole may be provided with at least one area  20 , 21 , 22 , 23  with corrugation-like projections  25 , confer FIG.  4 . The dotted lines  25  indicate the “vales” of the corrugations.  FIG. 5  illustrate some corrugations  25  in enlarged scale and in cross-section. 
     As shown the corrugations may be substantially parallel in each area. 
     As shown in  FIG. 4  an area  20  with a number of, preferably at least three, parallel corrugations may be provided within the heel zone  4 , said corrugations extending substantially perpendicular to the longitudinal axis  10  of the sole, confer FIG.  1 . The “vales” of the corrugations are also here indicated at  25 . 
     In the areas  21 ,  22 ,  23  within the finger-shaped zones  18   a ,  18   b ,  18   c  and/or in an area  27  opposite the zone of the ball of the foot in the elastic portion a system of substantially parallel corrugations  25  may be provided, optionally said corrugations substantially following curved lines, eg of a fairly light curvature. 
     As shown in  FIG. 4 , the corrugations  21 ,  22 ,  23  within the zone of each finger  18   a ,  18   b ,  18   c  may form an angle with the longitudinal axis  10  of the midsole, said angle v 1  being about 70-80° as regards the finger zone  18   c  adjacent the hallux zone  15  of the midsole and the angle v 2  of the corrugations in the finger zone  18   a  adjacent the little toe zone  28  being about 40-60°. 
     The particularly elastic portion  16  in the midsole may extend substantially from the centre of the heel zone to a position past the zone of the ball of the foot  27 , but ends prior to the toe zone of the midsole  1 . 
     As shown in  FIG. 6 , a part  16   a  of the particularly elastic portion  16  may extend upwards in one or both of the lateral parts of the sole at the instep of the sole. 
     The finished shoe sole normally consists of the midsole  1  according to the invention, an insole, a sock of the sandwich type atop the insole, and an outsole provided beneath the midsole  1 . The sock is shown in  FIG. 7  at reference numeral  35 . The sock may have a smooth portion  36 , preferably of leather or plastics in its hallux zone and in at least one portion of the zone of the ball of the foot. In connection with the present midsole, this embodiment of the sock has proved to further enhance the walking comfort. 
     The invention may be modified in many ways without thereby deviating from the scope of the invention, as it appears from the attached claims.