Abstract:
A hybrid outsole construction comprises high-density carbon rubber molded to low-density blown rubber, providing increased flexibility, cushion, and comfort while maintaining durability, traction, and shock absorbency of the footwear. In accordance with another aspect of the present invention, the hybrid outsole construction is stitched to the upper layers of the footwear, for example using a welt.

Description:
[0001]    This application claims the priority of U.S. Provisional Patent Application No. 60/327,139, filed Oct. 3, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to footwear, particularly to footwear to be used in a rugged environment, of lighter weight, additional comfort, and durability.  
           [0004]    2. Description of Related Art  
           [0005]    A principal goal in shoe design is to design footwear that is sturdy enough to protect the wearer&#39;s feet, yet flexible enough to provide for comfortable walking. This is particularly true for rugged footwear such as work boots or hiking boots, where comfort is often compromised in a design for well-built footwear that can withstand harsh conditions.  
           [0006]    The outsole of rugged footwear is designed to resist wear, provide durability, traction and absorb shock. Commonly, the outsole material is made of high-density carbon rubber, which is a relatively heavy and durable but stiff material. High-density carbon rubber provides very little in the area of flexibility and cushion. Thus, the construction of an outsole of a rugged footwear must take into account the weight, flexibility and durability of materials used in providing the necessary comfort and strength to the footwear.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed to a hybrid outsole construction comprised of high-density carbon rubber and low-density blown rubber, providing increased flexibility, cushion, and comfort while maintaining durability, traction, and shock absorbency of the footwear. Unlike prior art outsole construction, the present invention makes use of a hybrid structure to manufacture the outsole. High-density carbon rubber molded to low-density blown rubber comprises the hybrid outsole construction.  
           [0008]    One aspect of the invention contains low-density blown rubber for added cushioning throughout the outsole as well as high-density carbon rubber for durability, especially in high-wear areas like the heel. A material for the low-density blown rubber should be flexible, such as EMAX. EMAX provides the desired flexibility, increased cushion, and lighter weight. Ethylene-vinyl acetate (EVA) can also be used instead of the blown rubber. Other low density, resilient synthetic plastic foam materials may be used, such as polyurethane, polyethylene and polyethylene vinyl acetate.  
           [0009]    The use of low-density blown rubber, made by injecting air into a rubber compound, is well known in prior art associated with fitness-related footwear. No prior art, however, suggests the use of low-density blown rubber for providing increased agility and padding in rugged footwear like work boots.  
           [0010]    Low-density blown rubber, however, is less durable against wear than high-density carbon rubber. High-density carbon rubber molded around the EMAX, exhibits good wear resistance characteristics and preserves the strength and efficacy of the footwear. In accordance with another aspect of the present invention, the hybrid outsole construction is stitched to the upper layers of the footwear, for example using a welt.  
           [0011]    In another aspect of the present invention, the hybrid outsole construction includes providing the high-density carbon rubber layer with holes to expose the underlying low-density blown rubber. Portions of the exposed low-density blown rubber can extend through the holes to be formed into structures such as treads.  
       
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       [0012]    The present invention will be more clearly understood when considered in conjunction with the accompanying drawings. In the following drawings, like reference numerals designate like or similar parts throughout the drawings.  
         [0013]    [0013]FIG. 1 is a right side view of a footwear incorporating a hybrid outsole construction in accordance with one embodiment of the present invention.  
         [0014]    [0014]FIG. 2 is a cross sectional view of the footwear shown in FIG. 1, taken along line  2 - 2 .  
         [0015]    [0015]FIG. 3 is a bottom view of the footwear shown in FIG. 1.  
         [0016]    [0016]FIG. 4 is a side view of one embodiment of a three-quarter-welt cup heel footwear showing the various components of the footwear including the hybrid outsole construction with exposed low-density blown rubber arch.  
         [0017]    [0017]FIG. 5 is a rear heel-sectional view taken along line  5 - 5  in FIG. 4.  
         [0018]    [0018]FIG. 6 is a front toe-sectional view taken along line  6 - 6  in FIG. 4.  
         [0019]    [0019]FIG. 7 is a side view of another embodiment of a lightweight welted footwear showing the various components of the footwear including the hybrid outsole construction, with high-density carbon rubber undersurface.  
         [0020]    [0020]FIG. 8 is a rear heel-sectional view taken along line  8 - 8  in FIG. 7.  
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]    The present description is the best contemplated mode of carrying out the invention. This description is made for the purpose of illustrating general principles of the invention and should not be taken in a limiting sense.  
         [0022]    [0022]FIG. 1 illustrates a right side view of a footwear or shoe  70  incorporating a hybrid outsole construction  75  in accordance with one embodiment of the present invention. The footwear  70  comprises an upper portion  80  and the hybrid outsole construction or the lower outsole portion  75 . The upper portion  80  is shaped to receive the right foot of a wearer and to secure the right foot of the wearer within the upper portion  80 . The lower outsole portion  75  is coupled to the upper portion  80 , and is adapted to support the weight of the wearer on top, and is capable of traction against rough outside contact surfaces on bottom. The lower outsole portion  75  comprises an outer sole layer  85  and an inner sole layer  90 . The outer sole layer  85  is formed from a substantially wear resistant material, such as high-density carbon rubber. The inner sole layer  90  is disposed between the upper portion  80  and the outer sole layer  85 . The inner sole layer  90  is formed from a substantially resilient cushioning material that is substantially softer than the wear resistant material forming the outer sole layer  85 . The resilient material can be low-density blown rubber, such as EMAX, EVA, polyurethane, polyethylene or polyethylene vinyl acetate. The lower outsole portion  75  can also comprise an upper sole layer  95  disposed between the upper portion  80  and the inner sole layer  90 . The upper sole layer  95  can be formed from the same wear resistant material, such as high-density rubber. The inner sole layer  90  is therefore sandwiched between the upper sole layer  95  and the outer sole layer  85 .  
         [0023]    The outer sole layer  85 , the inner sole layer  90 , and the upper sole layer  95  are coextensive along their lengths and widths. As shown in FIG. 1, the inner sole layer  90  is exposed along its perimeter sides. In some embodiments of the present invention, the exposed sides of the inner sole layer  90  allow the inner sole layer  90  to deform or expand laterally as the wearer applies vertical pressure to the lower outsole portion  75 . The amount of deformation will depend on the resilience of the inner sole layer material  90 . In some embodiments of the present invention, the inner sole layer  90  will not substantially deform under application of vertical pressure.  
         [0024]    In the embodiment shown in FIG. 1, the inner sole layer  90  has a variable thickness along its length. The inner sole layer  90  is thicker at a heel section  100  of the lower outsole portion  75  than at a toe section  105  of the lower outsole portion  75 . Since vertical pressure can be greatest at the heel section  100 , the additional thickness at the heel section  100  allows for additional cushion at the heel section  100  to provide additional wearer comfort. In some embodiments of the present invention (not shown), the thickness of the inner sole layer  90  is uniform along its length.  
         [0025]    The lower outsole portion  75  may be assembled to the upper portion  80  using a welt construction, such as the American Goodyear welt  110 . The American Goodyear welt  110  is used for heavy-duty shoe construction, such as a work boot or hiking boot. The welt construction utilizes treated cotton twine to stitch the welt  110  to the upper portion  80  and to the lower outsole portion  75 . As shown in FIG. 1, the welt  110  can run around the entire perimeter of the upper portion  80  and the lower outsole portion  75 . Alternatively, the welt can run around the front perimeter of the toe area and approximately three-quarters the inner and outer length of the footwear ending at the cup heel (not shown).  
         [0026]    [0026]FIG. 2 is a cross sectional view of the footwear  70  shown in FIG. 1, taken through line  2 - 2 . The outer sole layer  85  comprises one or more holes  115  defined through the layer  85 . The holes  115  expose the underlying inner sole layer  90 , allowing portions of the inner sole layer  90  to extend and be formed through the holes  115 . For example, portion  92  of the inner sole layer  85  can be formed into a tread.  
         [0027]    [0027]FIG. 3 illustrates a bottom view of the footwear  70  shown in FIG. 1. The outer sole layer  85  includes a plurality of treads  87  for contact with the ground. The treads  87  can have any shape and pattern that allows for optimum traction with the ground. FIG. 3 also illustrates a plurality of treads  92  formed from portions of the inner sole layer  90  exposed through the holes  115  in the outer sole layer  85 . Treads  92  and  87  form a contact surface with the ground. As treads  92  contact with the ground, the more resilient treads  92  can provide additional impact absorption, while the more wear resistant treads  87  can provide sufficient traction with the ground.  
         [0028]    [0028]FIG. 4 illustrates a side view of one embodiment of the present invention by way of illustration only and not by limitation, a three-quarter-welt cup heel footwear  10  incorporating a hybrid outsole construction  14 . It is noted that the illustration shows the right side of the footwear. The three-quarter-welt cup heel footwear  10  is made of an upper  12  that is created to conform to the shape of the right foot of the wearer, and the hybrid outsole  14  for support of the weight of the wearer on top and for traction against rough outside contact surfaces on bottom. The hybrid outsole  14  is comprised of layers of different materials: a wear resistant layer of high-density carbon rubber (outer sole layer)  16  trimmed at the edges, and a relatively soft, cushion layer of low-density blown rubber (inner sole layer)  18 , such as EMAX, untrimmed and set back from the outsole sidewall, which is made of the high-density carbon rubber  16 . Other low density, resilient synthetic plastic foam materials may be used in place of EMAX, such as EVA, polyurethane, polyethylene and polyethylene vinyl acetate.  
         [0029]    The hybrid outsole construction  14  is achieved by molding the high-density carbon rubber  16  around certain areas of previously created low-density blown rubber  18 . High-density carbon rubber  16  bounds the low-density blown rubber  18  on all sides (e.g., underneath the upper  12 , at the toe and heel areas, and the bottom), but not on the lateral sides and the underside of an arch area  28 . Without high-density carbon rubber underneath the arch  28 , the footwear  10  can be more flexible to the wearer&#39;s movement.  
         [0030]    In some embodiments of the present invention, because the low-density blown rubber  18  is not bound on all sides and because it is set back or recessed from the outsole sidewall, space is provided to allow the low-density blown rubber  18  to substantially deform or expand laterally as vertical pressure (i.e., under the weight of the wearer) is applied to the hybrid outsole  14 . Further, the low-density blown rubber  18  in the arch area  28  substantially deforms into the space beneath the arch area  28  when vertical pressure is applied to the hybrid outsole  14 . When the pressure is removed, the low-density blown rubber  18  recovers its shape and once again is recessed from the outsole sidewall. In some embodiments of the present invention (not shown), the low-density blown rubber  18  does not substantially deform under the vertical pressure.  
         [0031]    The hybrid outsole  14  may be assembled to the upper  12  using a welt construction, such as the American Goodyear welt  20 , which utilizes stitching  22 , with treated cotton twine, the welt to the upper  12  and the outsole  14  (e.g., for a heavy duty shoe construction, such as a work boot or hiking boot). The welt  20  runs around the front perimeter of the toe area and approximately three-quarters the inner and outer length of the footwear  10  ending at the cup heel  24 .  
         [0032]    [0032]FIG. 5 illustrates a rear heel-sectional view of FIG. 4 displaying the hybrid outsole  14  and its components: the high-density carbon rubber  16 , which is trimmed at the edges of the footwear; and the low-density blown rubber  18 , which is untrimmed and recessed from the high-density carbon rubber  16  sidewall. FIG. 5 shows the state in which the low-density blown rubber  18  expands laterally to a convex profile, acting as a cushion when vertical weight is applied. When the weight is removed, the low-density blown rubber  18  contracts back to its original position, with the lateral edge of the rubber  18  in a concave profile (see dotted line  17 ). The cup heel  24  and the high-density carbon rubber  16  of the hybrid outsole  14  are one continuous piece of rubber. The cup heel  24  may be cement lasted and stitched.  
         [0033]    [0033]FIG. 6 illustrates a front toe-sectional view of FIG. 4 showing the hybrid outsole  14  consisting of high-density carbon rubber  16  and low-density blown rubber  18 . As shown in FIG. 6, when vertical pressure is applied to the hybrid outsole  14 , the low-density blown rubber  18  expands laterally here as well, forming a convex profile. When vertical pressure is released, the sidewall of the rubber  18  contracts to a concave profile  17 .  
         [0034]    [0034]FIG. 7 illustrates a side view of another embodiment of a hybrid outsole  54 , a lightweight welted footwear  50 . The hybrid outsole  54  is comprised of trimmed high-density carbon rubber (outer sole layer)  56  and untrimmed, recessed, low-density blown rubber (inner sole layer)  58 , such as EMAX. The high-density carbon rubber  56  covers the low-density blown rubber  58  in certain areas: at the top, bottom, front and back, but not on the sides. The low-density blown rubber  58  is able to substantially deform and expand laterally as pressure is applied vertically to the hybrid outsole  54 . When the pressure is removed, the low-density blown rubber  58  will contract to its original state. Alternatively, the low-density rubber  58  does not substantially deform under the applied pressure.  
         [0035]    The hybrid outsole  54  is assembled to the upper  52  with a welt  60  and treated cotton twine stitching  62 . The stitching  62  extends through the hybrid outsole  54 , the welt  60 , and the upper  52 . The welt  60  runs completely around the lightweight welted footwear  50 .  
         [0036]    [0036]FIG. 8 illustrates a rear heel-sectional view of FIG. 7 displaying the trimmed high-density carbon rubber  56  and the untrimmed, recessed, low-density blown rubber  58  comprising the hybrid outsole  54 . When vertical pressure is applied to the hybrid outsole, the low-density blown rubber  58  expands laterally until the pressure is removed, retracting back to a convex profile  17 .  
         [0037]    While the invention has been described in detail with respect to the illustrated embodiments in accordance therewith, it will be apparent to those skilled in the art that various changes, modifications, substitutions, alterations and improvement may be made without departing from the scope and spirit of the invention as defined by the appended claims.