Footwear with an air cushion and a method for making the same

[0001] 1. Field of the Invention

[0002] This invention relates to footwear with an air cushion and a method for making the same.

[0003] 2. Description of the Related Art

[0004] FIGS. 1 and 2 illustrate a conventional shoe disclosed in U.S. Pat. No. 4,722,131. The shoe includes an upper 8, an outsole 9, and an air cushion 7 sandwiched between the upper 8 and the outsole 9. The air cushion 7 is made from an elastomeric material so as to be inflatable up to about 40 psi, and is formed with a plurality of depressions 70 for the purpose of providing vertical support thereto. Since the air cushion 7 is made from an elastomeric material, it is relatively soft. As a consequence, the strength of the vertical support given by the depressions 70 to the air cushion 7 is insufficient. A foam material can be used to encapsulate the air cushion 2 and fill the depressions 70 so as to enhance the strength of the vertical support to the air cushion 7. However, the foam material is also a soft material. As such, there is still a need to enhance the strength of the vertical support to a conventional air cushion. Moreover, using a foam material to enhance the strength of the vertical support to the air cushion significantly increases the manufacturing cost of the shoe. The depressions 70 divide the air cushion 7 into a plurality of cells that are in fluid communication with one other. However, the structure as such is disadvantageous in that once the air cushion 70 is compressed at one end thereof, the other end of the air cushion 70 expands, so that said one end of the air cushion 70 will be significantly depressed, which results in an imbalance in the cushioning effect between the two ends of the air cushion 70 and insufficient cushioning at said one end of the air cushion 70.

[0005] Therefore, the object of the present invention is to provide an article of footwear that is capable of overcoming the aforementioned drawbacks.

[0006] Another object of this invention is to provide a method for making the article of footwear of this invention.

[0007] According to one aspect of the present invention, an article of footwear comprises: an upper having a peripheral wall with a bottom end that defines a bottom opening, and an insole that covers the bottom opening and that is connected to the bottom end of the peripheral wall; an outsole spaced apart from and vertically aligned with the insole, having a horizontal base, and formed with a plurality of studs that project from the horizontal base toward the insole; and an air cushion sandwiched between the insole and the outsole and including a top wall that is bonded to the insole and that has a peripheral edge, a bottom wall that is bonded to the outsole and that has a peripheral edge, and a cushion peripheral wall that interconnects the peripheral edges of the top and bottom walls, and that cooperates with the top and bottom walls to confine an air chamber thereamong. The bottom wall has a horizontal wall portion that is bonded to the horizontal base of the outsole, and a plurality of grooves, each of which is confined by a groove-confining wall that extends inwardly from the horizontal wall portion into the air chamber. Each of the studs extends into a respective one of the grooves, and has an outer surface that conforms and that is bonded to the groove-confining wall.

[0008] According to another aspect of the present invention, a method for making an article of footwear comprises the steps of: preparing an upper that has a peripheral wall with a bottom end that defines a bottom opening, and an insole that covers the bottom opening and that is connected to the bottom end of the peripheral wall; preparing an outsole having a horizontal base, and formed with a plurality of studs that project from the horizontal base; mounting the upper on a last; forming an inflatable air cushion that includes a top wall with a peripheral edge, a bottom wall with a peripheral edge, and a cushion peripheral wall interconnecting the peripheral edges of the top and bottom walls and cooperating with the top and bottom walls to confine an air chamber thereamong, the bottom wall having a horizontal wall portion, and a plurality of grooves, each of which is confined by a groove-confining wall that extends inwardly of the air chamber from the horizontal wall portion; placing and assembling the air cushion, the outsole, and the upper which is mounted on the last in a mold in such a manner that the air cushion is sandwiched between the insole and the outsole, that the top wall confronts the insole, that the horizontal wall portion of the bottom wall confronts the horizontal base, and that each of the studs extends into a respective one of the grooves; injecting air into the air chamber so as to permit expansion of the air cushion and so as to permit abutment of the cushion peripheral wall against an inner side wall of the mold, abutment of the top wall against the insole, and abutment of the horizontal wall portion of the bottom wall against the horizontal base; and thermally molding assembly of the air cushion, the outsole, and the upper in the mold so as to shape the cushion peripheral wall in accordance with the shape of the inner side wall of the mold and so as to permit bonding between the top wall and the insole, between the horizontal wall portion of the bottom wall and the horizontal base, and between each of the studs and the respective groove-confining wall.

[0020] For the sake of clarity, like elements are denoted by the same reference numerals throughout the disclosure.

[0021] FIG. 3 illustrates a preferred embodiment of an article of footwear of this invention. The article of footwear includes: an upper 3 having a peripheral wall 32 with a bottom end 320 that defines a bottom opening, and an insole 34 that covers the bottom opening and that is connected to the bottom end 320 of the peripheral wall 32; an outsole 31 spaced apart from and vertically aligned with the insole 34, having a horizontal base 310, and formed with a plurality of studs 311 that project from the horizontal base 310 toward the insole 34; and an air cushion 35 sandwiched between the insole 34 and the outsole 31 and including a top wall 351 that is bonded to the insole 34 and that has a peripheral edge 3510, a bottom wall 352 that is bonded to the outsole 31 and that has a peripheral edge 3520, and a cushion peripheral wall 353 that interconnects the peripheral edges 3510, 3520 of the top and bottom walls 351, 352, and that cooperates with the top and bottom walls 351, 352 to confine an air chamber 36 thereamong. The bottom wall 352 has a horizontal wall portion 3521 that is bonded to the horizontal base 310 of the outsole 31, and a plurality of grooves 3522, each of which is confined by a groove-confining wall 3523 that extends inwardly from the horizontal wall portion 3521 into the air chamber 36. Each of the studs 311 extends into a respective one of the grooves 3522, and has an outer surface 3110 that conforms and that is bonded to the groove-confining wall 3523 so as to provide vertical support to the air cushion 35. Since the outsole 31 is normally made from a material that has a hardness greater than that of the air cushion 35, the problem of insufficient strength of the vertical support encountered in the prior art can be eliminated. Moreover, the drawback with respect to the relatively high manufacturing cost of the shoe of the prior art resulting from the formation of the foam body on the air cushion can be overcome.

[0022] The horizontal base 310 of the outsole 31 has a peripheral edge 3101. The peripheral wall 32 of the upper 3 has a bottom portion 321. The outsole 31 further has a top peripheral flange 312 that has a lower portion 3121 extending upwardly from the peripheral edge 3101 of the horizontal base 310 and surrounding and bonded to the cushion peripheral wall 353 of the air cushion 35, and an upper portion 3122 extending upwardly from the lower portion 3121 and surrounding and bonded to the bottom portion 321 of the peripheral wall 32 of the upper 3.

[0023] Referring to FIGS. 5 to 8, in combination with FIG. 4, the article of footwear of this invention can be made by a method including the steps of: preparing the upper 3 and the outsole 31; mounting the upper 3 on a last 30; forming the air cushion 35 which is made from polyurethane and which is inflatable; placing and assembling the air cushion 35, the outsole 31, and the upper 3 which is mounted on the last 30 in a mold 40 in such a manner that the air cushion 35 is sandwiched between the insole 34 and the outsole 31, that the top wall 351 confronts the insole 34, that the horizontal wall portion 3521 of the bottom wall 352 confronts the horizontal base 310, and that each of the studs 311 extends into a respective one of the grooves 3522; injecting air into the air chamber 36 so as to permit expansion of the air cushion 35 and so as to permit abutment of the cushion peripheral wall 353 against an inner side wall 411 of a pair of side mold parts 41 of the mold 40, abutment of the top wall 351 against the insole 34, and abutment of the horizontal wall portion 3521 of the bottom wall 352 against the horizontal base 310; and thermally molding assembly of the air cushion 35, the outsole 31, and the upper 3 in the mold 40 so as to shape the cushion peripheral wall 353 in accordance with the shape of the inner side wall 411 of the side mold parts 41 of the mold 40 and so as to permit bonding between the top wall 351 and the insole 34, between the horizontal wall portion 3522 of the bottom wall 352 and the horizontal base 310, and between each of the studs 311 and the respective groove-confining wall 3522. Since the cushion peripheral wall 353 is pressed against the inner side wall 411 of the side mold part 41 during the molding stage, the cushion peripheral wall 353 is capable of being patterned in accordance with the pattern on the inner side wall 411 of the side mold part 41.

[0024] The cushion peripheral wall 353 of the air cushion 35 is formed with an air inlet 16 at a heel position of the article of footwear for passage of air into the air chamber 36, and an air outlet 17 opposite to the air inlet 16 at a toe position of the article of footwear for passage of air out of the air chamber 36 during the injection stage. The injected air is heated prior to the injection stage, and is caused to continuously flow out of the air chamber 36 via the air outlet 17 during the injection stage so as to preheat and to soften the air cushion 35 prior to the molding stage, thereby facilitating patterning of the cushion peripheral wall 353 of the air cushion 35 and expediting the molding operation.

[0025] FIGS. 9 and 10 illustrate second and third preferred embodiments of the article of footwear of this invention which are similar to that shown in FIG. 4, except that the air cushion 35 of the second or third preferred embodiment includes a plurality of partitions 354 that sealingly interconnect the top and bottom walls 351, 352, which are flat, to divide the air chamber 36 into a plurality of closed cells 356 so as to enhance the vertical support to the air cushion 35. Each of the partitions 354 is formed with an aperture 355 so as to permit fluid communication between adjacent closed cells 356. The closed cells 356 of the air cushion 35 of FIG. 9 form a honeycomb structure, whereas the closed cells 356 of the air cushion 35 of FIG. 10 form a square grid structure.

[0026] With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.