Abstract:
A midsole adapted for attachment to a shoe having multiple layers of varying materials each having a different hardness level. More particularly, the present midsole includes a top, middle and bottom layer wherein all three layers of material have a different hardness range and wherein at least one of the layers is made from thermoplastic rubber (TPR). In one embodiment, the thermoplastic rubber (TPR) layer lies between the top and bottom layers and in another embodiment, the thermoplastic rubber (TPR) layer is the bottom layer. The thermoplastic rubber (TPR) layer may also have a length shorter than the other two layers forming the midsole.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to the construction of a shoe and, more particularly, to a midsole construction with improved comfort and shock absorption to enhance the comfort of a user&#39;s foot. 
         [0002]    The footwear industry has seen numerous design features introduced over the years in order to enhance the comfort, cushioning, resiliency and shock absorption capabilities of a shoe. Many of the technological advances have occurred in the sole, particularly the midsole. In most footwear, the midsole often provides both protective cushioning and shock absorption for the user&#39;s foot. In an effort to provide improved performance, it is often desirable to vary the support characteristics of the sole from one region to another. A wide variety of soles have been developed to provide variable support for the foot. These advances include using air cushioning systems such as air cavities or air bladders disposed within the sole of a shoe Although a marked improvement over conventional uniform sole constructions has occurred over the years, there still remains a need for a midsole construction that can be adapted to provide additional comfort and shock absorption to the wearer&#39;s foot. 
         [0003]    It would therefore be desirable to provide an improved midsole construction which is capable of providing increased comfort and shock absorption for the foot without using air cavities and/or air bladders to achieve the same. 
       SUMMARY OF THE INVENTION 
       [0004]    A shoe is generally composed of an upper connected to a sole. The sole of a shoe is generally comprised of an outsole, a midsole, an insole, and on occasion, a sock liner. The present invention is directed to an improved midsole construction having multiple layers of varying materials, each layer of material having a different hardness/softness level. 
         [0005]    In one aspect of the present invention, a midsole is provided which includes a three-layered construction, namely, a top layer, a middle layer and a bottom layer. The top layer provides a layer of material between the insole of the shoe and the second or middle layer of the midsole; the middle layer provides cushioning to the foot; and the bottom layer provides additional cushioning and a contacting surface for the outsole. In one embodiment, the top layer is made of a polyurethane material with a hardness in the range of 60-90° Asker C hardness, the middle layer is made of a thermoplastic rubber material with a hardness in the range of 20-65° Asker C hardness, and the bottom layer is made of a polyurethane material with a hardness in the range of 20-50° Asker C hardness. In one embodiment, the middle layer spans the heel portion of the shoe only and includes an upper surface which mates with and attaches to a portion of the bottom surface of the top layer and a bottom surface which mates with and attaches to a portion of the upper surface of the bottom layer. As a result, in the forefront area of the shoe, the bottom surface of the top layer mates with and attaches directly to the upper surface of the bottom layer. The bottom layer provides a layer of material between the outsole of the shoe and the second or middle layer of the midsole in the heel portion of the shoe and a layer of material between the outsole of the shoe and the top layer of the midsole in the forefront portion of the shoe. The three layers of the midsole have varying hardness/softness levels with the top layer being harder than the middle and bottom layers and with the middle layer being harder than the bottom layer. These layers can be attached to each other by any suitable means such as cement adhesion and/or stitching. 
         [0006]    In another embodiment, the three layers of material forming the midsole are re-arranged such that the top layer is harder than the middle and bottom layers but the middle layer is softer than the bottom layer. In one embodiment, the bottom layer has an upper surface which mates with and attaches to only a portion of the bottom of the middle midsole layer and the bottom surface thereof mates with and attaches to a portion of the upper surface of the outsole in the heel portion of the shoe. In this particular embodiment, the middle layer of the midsole attaches directly to the upper surface of the outsole in the forefront portion of the shoe. 
         [0007]    It is an object of the present invention to provide a midsole which provides enhanced comfort and shock absorption by utilizing multiple layers of varying materials which are likewise of varying hardness/softness levels. 
         [0008]    Specific advantages and features of the present midsole construction will be apparent from the accompanying drawings and the description of the several embodiments of the present invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of one embodiment of a shoe constructed in accordance with the teachings of the present invention. 
           [0010]      FIG. 2  is an exploded view of the shoe of  FIG. 1  showing construction of the midsole. 
           [0011]      FIG. 3  is an exploded view of the embodiment of the midsole shown in  FIG. 2 . 
           [0012]      FIG. 4  is an exploded view of another embodiment of the midsole of the shoe shown in  FIG. 1 . 
           [0013]      FIG. 5  is an exploded view of the embodiment of the midsole shown in  FIG. 4 . 
           [0014]      FIG. 6  is a rear elevational view of the bottom layer of the midsole embodiment shown in  FIGS. 4 and 5 . 
       
    
    
       [0015]    It should be understood that the drawings are not necessarily to scale and that the embodiments disclosed herein are sometimes illustrated by fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. It should also be understood that the invention is not necessarily limited to the particular embodiments illustrated herein. Like numbers utilized throughout the various figures designate like or similar parts or structure. 
       DETAILED DESCRIPTION 
       [0016]    A shoe generally includes an upper and a sole assembly that is affixed to the upper. The sole assembly generally includes an insole, a midsole, and an outsole, each having a peripheral shape designed to conform to the shape of a wearer&#39;s foot. To facilitate disclosure of the present invention, reference will be made to various general areas of the foot, such as the heel, arch and forefoot areas. When used to refer to locations on the various sole components, these terms should be interpreted to include those areas of the midsole and outsole that are disposed generally (and not necessarily directly) beneath the corresponding elements of the foot. It should be understood, however, that the boundaries between the heel, arch and forefoot areas are not precise and that these terms should be interpreted loosely and with a great deal of flexibility. 
         [0017]    Referring now to the drawings and, in particular,  FIGS. 1-3 , a first embodiment of a new and improved shoe midsole construction having multiple layers embodying the principles and concepts of the present invention and generally designated by the reference numeral  20  in  FIGS. 2 and 3  will be described. 
         [0018]    A shoe  12  ( FIG. 1 ) generally includes an upper  14  and a sole assembly  16  that is affixed to the upper  14 . Sole assembly  16  typically includes an insole  18 , a midsole  20 , and an outsole  22  and is attached to the upper  14  using a conventional method of attachment such as an adhesive, stitching or injection molding. In the embodiment illustrated in  FIG. 1 , the insole  18  is formed as part of the upper  14 . The midsole  20  includes three layers, a top layer  24 , a middle layer  26  and a bottom layer  28 . The midsole  20 , as shown in  FIGS. 2 and 3 , has an upper surface  30  and a bottom surface  32 . The top layer  24  of the midsole  20  can be attached via conventional means to either an insole such as insole  18 , or to the upper  14 , while the bottom surface  32  of bottom layer  28  is attached to the outsole  22  using a conventional method of attachment. 
         [0019]    Top layer  24  of the midsole  20  is positioned below the insole  18  and above the middle layer  26  of the midsole  20 . The specific material of the top layer  24  may be chosen depending upon the nature and type of shoe in which it will be used. Top layer  24  may be made from a variety of materials including, but not limited to, molded Polyurethane (PU), Polyvinyl Chloride (PVC), Thermoplastic Urethane (TPU), Thermoplastic Rubber (TPR), vulcanized rubber, ethyl vinyl acetate (EVA), rubberlon, or any other synthetic or natural material. The material forming the top layer  24  has a hardness factor greater than the middle and bottom layers  26  and  28  and is generally in the range of 60-90° Asker C hardness. The material and hardness/softness ranges selected will be determined by the type of footwear onto which midsole  20  is intended to be placed. 
         [0020]    Lying underneath top layer  24  of the midsole  20  is a middle layer  26  having an upper surface  36  and a bottom surface  40 . In the embodiment illustrated in  FIGS. 2 and 3 , the middle layer  26  only extends across the heel portion of top layer  24  and bottom layer  28  and may be made from a variety of materials including, but not limited to, TPR. The upper surface  36  of middle layer  26  is attached to the bottom surface  34  of the top layer  24  at the heel portion of the sole  16  using a conventional method of attachment, such as adhesive, while the bottom surface  40  of the middle layer  26  is attached to the upper surface  38  of the bottom layer  28  in the heel portion of the sole  16 . In contrast, the bottom surface  34  of the top layer  24  is attached directly to the upper surface  38  of bottom layer  28  in the arch and forefoot areas of the sole  16 . The middle layer  26  may further be secured to the top layer  24  by utilizing male connection portions, projections or components  42  associated with the bottom surface  34  of the top layer  24  which portions  42  mate with and engage corresponding female connection portions, openings or components  44  associated with the middle layer  26  as best shown in  FIG. 3 . Regardless of the type of material used for the middle layer  26 , the middle layer  26  is softer than the top layer  24  and is generally of a hardness in the range of 20-65° Asker C hardness, and preferably in the range of 40-60° Asker C hardness. 
         [0021]    The bottom layer  28  of the present midsole  20  is positioned below the middle layer  26  in the heel area of the sole  16  and below the top layer  24  in the arch and forefront areas of the sole  16  and above the outsole  22 . The specific material of the bottom layer  28  may again be chosen depending upon the nature and type of shoe in which it will be used. The bottom layer  28  may be made from a variety of materials including, but not limited to, molded Polyurethane (PU), Polyvinyl Chloride (PVC), Thermoplastic Urethane (TPU), Thermoplastic Rubber (TPR), vulcanized rubber, EVA, rubberlon, or any other synthetic or natural material. The material forming the bottom layer  28  has a hardness factor which is softer than both the top layer  24  and the middle layer  26  and is generally in the range of a 20-50° Asker C hardness, and preferably in the range of 20-40° Asker C hardness. The material and hardness/softness ranges selected will again be determined by the type of footwear onto which midsole  20  is intended to be placed. The upper surface  38  of the bottom layer  28  of the midsole  20  is attached to the bottom surface  40  of the middle layer  26  of the midsole  20  in the heel portion of the sole  16  using a conventional method of attachment, while the upper surface  38  of the bottom layer  28  of the midsole  20  in the arch and forefront areas of the shoe  16  is attached directly to the bottom surface  34  of the top layer  24  of the midsole likewise using conventional means. 
         [0022]    In the particular embodiment illustrated in  FIGS. 2 and 3 , the middle layer  26  of midsole  20  is utilized to provide additional comfort to the wearer of the shoe  12  in that the middle layer  26  acts as a cushioning means to further cushion the heel of the wearer as the heel portion of the shoe  12  strikes the ground during a normal gait. In some embodiments, the middle layer  26  may be comprised of a gel type material which provides increased shock absorption and energy return whereas the top and bottom layers  24  and  28  of the midsole  20  can be made of a dual density lightweight material which likewise provide support and shock absorption. It is also recognized and anticipated that in some embodiments, the middle layer  26  of the midsole  20  may extend beyond the heel portion of the sole  16  to include the arch area and/or forefoot area of the sole  16  as well, or portions thereof. Regardless of the types of materials used for each of the three separate layers  24 ,  26  and  28  associated with the present midsole construction  20 , improved comfort and cushioning is achieved in this particular midsole construction due to the fact that the top layer  24  of the midsole  20  is harder than the middle layer  26  of the midsole  20 , which, in turn, is harder than the bottom layer  28  of the midsole  20 . Stated another way, the bottom layer  28  is softer than the middle layer  26  which, in turn, is softer than the top layer  24  of the midsole construction  20 . This arrangement of layers and hardness factors provides for improved comfort and cushioning to the wearer of the shoe  12 . 
         [0023]    In another embodiment, referring now to the drawings and, in particular,  FIGS. 4-6 , a second embodiment of a new and improved shoe midsole construction having multiple layers embodying the principles and concepts of the present invention and generally designated by the reference numeral  46  in  FIGS. 4 and 5  will be described. 
         [0024]    In the embodiment illustrated in  FIG. 4 , the insole  18  is again formed as part of the upper  14 . The midsole  46  includes three layers, a top layer  48 , a middle layer  50  and a bottom layer  52 . The midsole  46 , as shown in  FIGS. 4-6 , has an upper surface  54  and a bottom surface  56 . The top layer  48  of the midsole  46  can be attached via conventional means to either an insole such as insole  18 , or to the upper  14 , while the bottom surface  56  of bottom layer  52  is attached to the outsole  22  using a conventional method of attachment. 
         [0025]    Top layer  48  of the midsole  46  is positioned below the insole  18  and above the middle layer  50  of the midsole  46 . The specific material of the top layer  48  may be chosen depending upon the nature and type of shoe in which it will be used. Top layer  48  may be made from a variety of materials including, but not limited to, molded Polyurethane (PU), Polyvinyl Chloride (PVC), Thermoplastic Urethane (TPU), Thermoplastic Rubber (TPR), vulcanized rubber, EVA, rubberlon, or any other synthetic or natural material. The material forming the top layer  48  has a hardness factor greater than the middle and bottom layers  50  and  52  and is generally in the range of 60-90° Asker C hardness. The material and hardness/softness ranges selected will be determined by the type of footwear onto which midsole  46  is intended to be placed. 
         [0026]    Lying underneath top layer  48  of the midsole  46  is a middle layer  50  having an upper surface  58  and a bottom surface  60 . Middle layer  50  of the midsole  46  is positioned below the top layer  48  and above the bottom layer  52  of the midsole  46 . The specific material of the middle layer  50  may be chosen depending upon the nature and type of shoe in which it will be used. Middle layer  50  may be made from a variety of materials including, but not limited to, molded Polyurethane (PU), Polyvinyl Chloride (PVC), Thermoplastic Urethane (TPU), Thermoplastic Rubber (TPR), vulcanized rubber, EVA, rubberlon, or any other synthetic or natural material. The material forming the middle layer  50  has a hardness factor lesser than the top and bottom layers  48  and  52  and is generally in the range of 20-50° Asker C hardness, and preferably in the range of 20-40° Asker C hardness. The material and hardness/softness ranges selected will be determined by the type of footwear onto which midsole  46  is intended to be placed. 
         [0027]    In the embodiment illustrated in  FIGS. 4 and 5 , the middle layer  50  extends across the entire length of the top layer  48 . The upper surface  58  of middle layer  50  is attached to the bottom surface  62  of the top layer  48  using a conventional method of attachment, such as adhesive, while the bottom surface  60  of the middle layer  50  is attached to the upper surface  64  of the bottom layer  52  in the heel portion of the sole  16  and to the upper surface  66  of the outsole  22  in its remaining portion, namely, in the arch and forefoot areas. 
         [0028]    The bottom layer  52  of the present midsole  46  is positioned below the middle layer  50  and above the outsole  22  and may be made from a variety of materials including, but not limited to, TPR. The upper surface  64  of bottom layer  52  is attached to the bottom surface  60  of the middle layer  50  at the heel portion of the sole  16  using a conventional method of attachment, such as adhesive, while the bottom surface  56  of the bottom layer  52  is attached to the upper surface  66  of the outsole  22  in the heel portion of the sole  16 . In contrast, the bottom surface  60  of the middle layer  50  is attached directly to the upper surface  66  of the outsole  22  in the arch and forefoot areas of the sole  16 . The bottom layer  52  may further be secured to the middle layer  50  by utilizing male connection portions, projections, flanges or components  68  associated with the top surface  64  of the bottom layer  52  as best shown in  FIG. 6 , which portions  68  mate with and engage corresponding female connection portions, cut-outs, cavities, notches or components  70  associated with the middle layer  50  as best shown in  FIGS. 4 and 5 . The flanges  68  mate with and engage the cut-outs  70  when the bottom layer  52  is attached to the middle layer  58 . Regardless of the type of material used for the bottom layer  52 , the bottom layer  52  is softer than the top layer  48  and is generally of a hardness in the range of 20-65° Asker C hardness, and preferably in the range of 40-60° Asker C hardness. 
         [0029]    In the particular embodiment illustrated in  FIGS. 4 ,  5  and  6 , the bottom layer  52  of midsole  46  is utilized to provide additional shock absorption to the wearer of the shoe  12  in that the bottom layer  52  acts as a shock absorption means to further absorb shock to the heel of the wearer as the heel portion of the shoe  12  strikes the ground during a normal gait. It is also recognized and anticipated that in some embodiments, the bottom layer  52  of the midsole  46  may extend beyond the heel portion of the sole  16  to include the arch area and/or forefoot area of the sole  16  as well, or portions thereof. Regardless of the types of materials used for each of the three separate layers  48 ,  50  and  52  associated with the present midsole construction  46 , improved shock absorption is achieved in this particular midsole construction due to the fact that the top layer  48  of the midsole  46  is harder than the middle layer  50  and bottom layer  52  of the midsole  46  and the bottom layer  52  is harder than the middle layer  50  of the midsole  56 . Stated another way, the bottom layer  52  is softer than the top layer  48 , but is harder than the middle layer  50  of the midsole construction  46 . This arrangement of layers and hardness factors provides for improved shock absorption to the wearer of the shoe  12 . 
         [0030]    Thus, there have been shown and described two embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.