Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
     Under 35 U.S.C. 120, this application is a Continuation of, claiming the benefit of and priority to, U.S. patent application Ser. No. 10/925,605, filed Aug. 24, 2004, now U.S. Pat. No. 7,331,123 the contents of which are hereby incorporated by reference as if recited in full herein for all purposes. 
    
    
     BACKGROUND AND SUMMARY 
     This invention relates to a shoe having a sole that can be quickly and easily replaced with other soles having different types of traction surfaces. 
     Shoes having replaceable soles are well known in the prior art. One such shoe, which is particularly adapted for use by fishermen, is sold by Korkers Products, LLC. This shoe is disclosed in patent application Ser. No. 10/293,188, now U.S. Pat. No. 6,813,847. This shoe includes a cavity in its sole which receives a sole plate having a tread pattern on its lower surface. A tab located at the front of the sole plate fits into a slot formed in the cavity sidewall to hold the front end of the sole plate in place. A strap, which is attached to the rear of the sole plate, can be attached to an attachment device located at the back of the shoe to hold the rear end of the sole plate in place. A piece of interfitting releasable fastener material may be located on the sole plate and sole near the center of the sole plate to hold the center of the sole plate in place. 
     While this shoe works well for its intended purpose, it does have several shortcomings. First, the interfitting releasable fastener loses its holding ability with repeated use, particularly when exposed to sand. Second, sand can get in the slot at the front of the cavity and cause the front end of the sole plate to become offset downwardly with respect to the remainder of the sole. Finally, the attachment device at the rear of the shoe which receives the strap attached to the rear of the sole plate is cumbersome to use, particularly in the field. 
     The subject invention overcomes the foregoing shortcomings of the prior art shoes having replaceable sole plates by providing a sole having a thin cavity which releasably receives a sole plate which substantially fills the cavity. The sidewall of the cavity includes flaps which are contiguous with the bottom surface of the sidewall and have a thickness which is less than the thickness of the cavity. Depressions located in the outer surface of the sole plate are arranged to receive the flaps when the sole plate is pushed past the flaps into the cavity. The flaps then hold the sole plate in the cavity. 
     In another aspect of the invention, a slot is located in the sidewall of the cavity at the toe end of the shoe and the sole plate has a tab at its front end which fits into the slot. In this embodiment the sidewall includes a ledge which extends into the cavity below the slot and the sole plate has a recess which is located below the tab and receives the ledge. Thus, when the sole plate is placed in the cavity the ledge and recess interfit to prevent sand from getting under the tab. 
     The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a shoe with a removable sole plate embodying the subject invention. 
         FIG. 2  is an exploded view of the shoe of FIG,  1  showing the sole plate removed from the remainder of the shoe. 
         FIG. 3  is a bottom view of the shoe of  FIG. 1 . 
         FIG. 4  is a sectional view, at an enlarged scale, taken on the line  4 - 4  in  FIG. 3 . 
         FIG. 5  is a cross-sectional view, at an enlarged scale, taken on the line  5 - 5  of  FIG. 3 . 
         FIG. 6  is an exploded side elevation, partially broken away, of the shoe of  FIG. 1 . 
         FIG. 7  is a partial side elevation view, at an enlarged scale, of another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The subject invention is referred to as a shoe, however it could be a boot or sandal as well and the word shoe is meant to cover any type of footwear. Referring now to  FIGS. 1 and 2  of the drawings, a shoe  10  has a sole  12  with a thin cavity  14  located centrally in it. The cavity is surrounded by a sidewall  16  having a bottom surface  18 , which is part of the shoe tread. The sidewall has a thickness a, which in the embodiment illustrated is approximately one-quarter inch. Located in the sidewall at the toe end of the cavity  14  is a thin slot  20 ,  FIG. 5 . The slot  20  preferably is at the top of the cavity  14 . Located around the periphery of the cavity  14  are a plurality of flaps  22 . The bottoms of the flaps are contiguous with the bottom surface  18  of the sidewall and they have a thickness b,  FIG. 4 , which is less than the thickness a. In the embodiment illustrated the flaps are located in pairs with one flap in each pair being on each side of the shoe. One pair of flaps  22  is located around where the ball of the user&#39;s foot would be, one pair is located around where the arch of the user&#39;s foot would be, and another pair is located around where the user&#39;s heel would be. The sidewall  18  includes a passageway  24  at its back edge which extends between the cavity  14  and the back of the shoe. 
     A sole plate  26  is sized to fit within and substantially fill the cavity  14 . The sole plate has generally the same thickness as the thickness of the sidewall, however, due to the tread pattern located on the bottom surface  27  of the sole plate its thickness varies. In any event, the bottom surface of the sole plate is generally flush with the bottom surface  18  of the sidewall  16  in order to provide a stable bottom on the shoe. The sole plate is made from an elastomeric material and preferably has a flexibility that is similar to that of the sole  12 . A thin tab  28  located at the toe end of the sole plate fits into the slot  20  when the sole plate is inserted into the cavity. In the embodiment illustrated the tab is an extension of a thin base layer  30  which forms the upper portion of the sole plate. The base layer is made from a plastic material, such as ABS, and is far less flexible than the remainder of the sole plate. In a preferred embodiment the base layer is glued to the remainder of the sole plate, but it could be joined by other means. Alternatively, there could be no base plate and the tab  28  could be integral with the rest of the sole plate. 
     Located at the heel end of the sole plate is a strap  32  which extends through the passageway  24  and up the back of the shoe. The strap is made from an elastically deformable material and has an opening  34  located near its end. A hook  36  located on the back of the shoe is configured to receive the opening. After the sole plate is placed in the cavity the strap is stretched to place the opening  34  over the hook  26  and when the strap is released its elasticity holds the rear end of the sole plate on the shoe. 
     Located around the periphery of the bottom surface of the sole plate are a plurality of depressions  38  which are arranged to receive the flaps  22  when the sole plate is inserted into the cavity. In the embodiment illustrated the depressions  38  extend to the more rigid base layer  30 . 
     The flaps  22  are elastically deformable and are flexible enough to be deflected upwardly to allow the portions of the base layer located above the depressions  38  to be snapped in place above the flaps when the sole plate is inserted into the cavity. Accordingly, the flaps and depressions may be considered engageable elements, each forming a male-female pair that provides an interference fit that helps secure the sole plate to the sole. However, the flaps are sufficiently stiff to hold the sole plate in place once the base layer is pushed past the flaps. In the embodiment illustrated the bottom edges  56  of the flaps  22 , and the top edges  58  of the portions of the base layer  30  located above the depressions  38  are rounded to facilitate pushing the base layer past the flaps. The flaps are somewhat harder than the remainder of the sidewall. Preferably, the flaps have a hardness of between 90 and 95 Shore A Durometer and the remainder of the sidewall has a hardness of between 80 and 85 Shore A Durometer. 
     A ledge  40  extends from the sidewall  18  into the cavity  14  below the slot  20 . The sole plate  26  includes a recess  42  which is located below the tab  28  and is configured to receive the ledge  40  when the sole plate is placed in the cavity. Thus the tip  44  of the sole plate which is below the recess  42  overlaps the ledge  40  and prevents sand from working its way into the slot  20  and forcing the tab outwardly causing a discontinuity between the outer surface of the sole plate and the outer surface of the sidewall at the toe end of the shoe. 
     While the use of the interlocking tab  28  and slot  20  at the toe end, the strap  32  and hook  36  at the heel end and the flaps  22  in between all prevent the sole plate from being pulled out of the shoe perpendicular to the sole plate, if the sole plate is strongly urged rearwardly it might pull free. To prevent this from occurring the top surface  46  of the cavity has an indented portion and the sole plate  26  has a projecting portion which interacts with the indented portion to prevent movement of the sole plate relative to the sole longitudinally along the shoe without first lifting the sole plate perpendicularly out of the cavity. In the embodiment shown in  FIGS. 1-6  the indented portion is an inwardly facing curved surface  48  located in the arch portion of the bottom surface  46  of the cavity, as can best be seen in  FIG. 6 . The sole plate  26  has an upwardly facing curved surface  50  which interacts with the curved surface  48  in the top of the cavity when the sole plate is placed in the cavity. 
     In another embodiment, shown in  FIG. 7 , the indented portion is a rectangular recess  52  which is located in the bottom surface  46  of the cavity. In this embodiment the projecting portion is a raised block  54  which fits into the recess  52  when the sole plate is placed in the cavity. The recess and block can have any shape, and can be multiple elements, such as a sawtooth pattern. 
     The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

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