Patent Publication Number: US-2022225731-A1

Title: Footwear midsole comprising a support and one or more internal bladders

Description:
TECHNICAL FIELD 
     The presently disclosed subject matter relates a midsole that can be used with a wide variety of footwear. 
     BACKGROUND 
     Athletic footwear generally includes a multilayer construction comprised of an upper and a sole. The upper is designed to comfortably enclose at least a portion of the wearer&#39;s foot, while the sole absorbs the harmful impact forces created during walking, running, and the like. The sole can be a single piece, but more commonly comprises an outsole, an insole, and a midsole therebetween. The outsole functions as a tough, wear-resistant layer with tread for providing traction against the ground or floor. The insole is a thin, soft layer that provides comfort to the user&#39;s foot. The midsole is the primary structural layer in the sole and provides shock absorption. The footwear midsole is generally constructed from a resilient foam material, such as ethylene vinyl acetate (EVA) or polyurethane, which provide cushioning and support to the wearer&#39;s foot. However, there are several drawbacks associated with these materials. For example, over time, foam midsoles quickly become worn through compaction of the foam material. As a result, the cushioning capacity of the shoe is greatly reduced, requiring the wearer to frequently replace the shoe. In addition, prior art midsoles comprising foam materials commonly store the energy from the foot strike while under compression, which can be immediately returned (referred to as energy return or rebound). It has been shown that foam rebound can produce undesirable shock to the wearer, leading to injury. Further, air has been used as a cushioning material in shoes for decades. However, prior art footwear includes air inserted directly into the sole. However, when the sole fully comprises fluid-filled bladders within a rigid cavity, improved cushioning, and impact reduction due to the constriction of air molecules is observed. It would therefore be beneficial to provide a midsole capable of shock absorption, improved cushion, advanced impact reduction, and improved performance while maintaining the structural integrity of the footwear. 
     SUMMARY 
     In some embodiments, the presently disclosed subject matter is directed to a footwear midsole. The midsole comprises a support defined by a lower face and a sidewall that extends in an upward direction about a perimeter of lower face, creating a cavity with an open top. The midsole also includes a plurality of elastomeric fluid-filled bladders positioned within the cavity of the support. The midsole enables top-down compression when a force is exerted upon the midsole. 
     In some embodiments, each bladder includes an inflation housing that allows fluid to be added or removed from the interior compartment. 
     In some embodiments, the fluid comprises a gas, a liquid, gel, or combinations thereof. 
     In some embodiments, the support is constructed from plastic, wood, carbon fiber, metal, or combinations thereof. 
     In some embodiments, the fluid is selected from ambient air, nitrogen, carbon dioxide, helium, or combinations thereof. 
     In some embodiments, the fluid is selected from water, saline, or combinations thereof. 
     In some embodiments, the support is constructed from one or more rigid or semi-rigid materials. 
     In some embodiments, the bladders are constructed from natural or synthetic rubber, natural or synthetic rubber blends, polyisoprene, polybutadiene, chloroprene rubber, butyl rubber, styrene-butadiene rubber, nitrile rubber, silicone, polyether block amides, ethylene-vinyl acetate, thermoplastic elastomers, polyurethane, polyester, polyester polyurethane, polyether polyurethane, or combinations thereof. 
     In some embodiments, the interior compartment of each bladder has a volume of about 10-200 cubic centimeters. 
     In some embodiments, the bladders are permanently attached to the midsole. 
     In some embodiments, the sidewall tapers from a first end of the support to a second end of the support. 
     In some embodiments, the sidewall has a first height at the first end that is about 20 to 90 percent of a second height at the second end. 
     In some embodiments, each bladder is filled to about 40-100 percent capacity. 
     In some embodiments, wherein the fluid within each bladder has a pressure of about 0-350 kPa. 
     In some embodiments, the presently disclosed subject matter is directed to an article of footwear comprising a sole and an upper. The sole comprises a midsole defined by a support defined by a lower face and a sidewall that extends in an upward direction about a perimeter of lower face, creating a cavity; and a plurality of elastomeric fluid-filled bladders positioned within the cavity of the support. The midsole enables top-down compression when a force is exerted upon the midsole. 
     In some embodiments, the sole further comprises an insole and an outsole. 
     In some embodiments, the sole lacks an insole, outsole, or both. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 a    is a side plan view of footwear comprising a midsole in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 1 b    is a side plan view of a footwear sole in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 2 a    is a perspective view of a midsole support in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 2 b    is a side plan view of a midsole support in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 2 c    is a side plan view of a midsole support in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 3  is a side plan view of a bladder in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 4 a    is a fragmentary view of a bladder inflation housing in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 4 b    is a fragmentary view of a bladder inflation housing in use in accordance with some embodiments of the presently disclosed subject matter. 
         FIGS. 5 a -5 b    are top plan views of midsoles comprising one or more bladders in accordance with some embodiments of the presently disclosed subject matter. 
         FIG. 5 c    is a fragmentary view of two bladders in accordance with some embodiments of the presently disclosed subject matter. 
         FIGS. 6 a -6 d    are side plan views of one embodiment of using the disclosed midsole. 
     
    
    
     DETAILED DESCRIPTION 
     The presently disclosed subject matter is introduced with sufficient details to provide an understanding of one or more particular embodiments of broader inventive subject matters. The descriptions expound upon and exemplify features of those embodiments without limiting the inventive subject matters to the explicitly described embodiments and features. Considerations in view of these descriptions will likely give rise to additional and similar embodiments and features without departing from the scope of the presently disclosed subject matter. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter pertains. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described. 
     Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in the subject specification, including the claims. Thus, for example, reference to “a device” can include a plurality of such devices, and so forth. 
     Unless otherwise indicated, all numbers expressing quantities of components, conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the instant specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter. 
     As used herein, the term “about”, when referring to a value or to an amount of mass, weight, time, volume, concentration, and/or percentage can encompass variations of, in some embodiments+/−20%, in some embodiments+/−10%, in some embodiments+/−5%, in some embodiments+/−1%, in some embodiments+/−0.5%, and in some embodiments+/−0.1%, from the specified amount, as such variations are appropriate in the disclosed packages and methods. 
       FIG. 1 a    illustrates one embodiment of footwear  5  configured as an athletic shoe that includes a midsole structure in accordance with the presently disclosed subject matter. The midsole can be configured for use with various kinds of footwear, such as hiking boots, soccer shoes, football shoes, running shoes, cross-training shoes, rugby shoes, basketball shoes, baseball shoes, and the like. It should be appreciated that the footwear can also include non-athletic shoes, such as slippers, sandals, high heeled shoes, loafers, etc. Thus, the term “footwear” broadly refers to any foot covering, including (but not limited to) athletic shoes, boots, sandals, and the like. 
     For reference purposes, footwear  5  can be divided into three general regions: forefoot region  30 , midfoot region  31 , and heel region  32 , as shown in  FIG. 1 a   . Forefoot region  30  generally includes portions of footwear  5  corresponding with the toes and the joints connecting the metatarsals with the phalanges. Midfoot region  31  generally includes portions of the footwear corresponding with the arch area of the foot, and heel region  32  corresponds with rear portions of the foot, including the calcaneus bone. It should be appreciated that regions  30 - 32  are not intended to demarcate precise areas of footwear  5 . Rather, the regions are intended to represent general areas of the footwear. 
     As shown, footwear  5  includes upper  10  designed to securely enclose at least a portion of the wearer&#39;s foot. Upper  10  can have any of a wide variety of configurations incorporating a range of conventional materials, such as (but not limited to) textiles, foam, leather, suede, vinyl, nylon, and the like. The material elements can be selected and positioned in upper  10  to selectively impart one or more desired properties (e.g., durability, air-permeability, wear-resistance, flexibility, comfort, and the like). The materials are stitched or adhesively bonded together to form interior void  20  for securely and comfortably receiving at least a portion of the wearer&#39;s foot. In some embodiments, upper  10  can include closure  25  configured as a shoelace, zipper, snap, button, VELCRO®, etc. that is utilized to secure the wearer&#39;s foot within the interior void of the footwear. The closure also facilitates entry and removal of the foot from the footwear. In some embodiments, the closure can extend through apertures in upper  10 , and a tongue portion can extend between the interior void and the closure. 
     It should be appreciated that upper  10  can have any design, shape, size and/or color. For example, in embodiments wherein the footwear is a basketball shoe, the upper can be configured as a high top that is shaped to provide added support on the wearer&#39;s ankle. Alternatively, when footwear  5  is a running shoe, upper  10  can be configured with a low profile. 
     In addition to upper  10 , footwear  5  comprises sole  15  that functions to absorb the impact forces on the wearer&#39;s foot during use. In some embodiments, the sole can extend generally the entire length of the footwear from toe region  16  to the heel portion  17 , as shown in  FIG. 1 a   . The sole is secured to a lower face of upper  10  using any known method, such as (but not limited to) the use of adhesive, sewing, thermal bonding, mechanical elements, and the like. The sole is positioned between upper  10  and the ground, thereby extending between the foot and the ground. In this way, the sole can provide traction, impart stability, and limit various foot motions (such as pronation). 
       FIG. 1 b    illustrates one embodiment of sole  15 . As illustrated, the primary elements of sole  15  include insole  35 , midsole  40  and outsole  33 . In some cases, one or more of these components can be optional. Insole  35  is positioned within the interior void in upper  20  and is located to correspond with a plantar (i.e., lower) surface of the foot, thereby enhancing the comfort of footwear  10 . Midsole  40  is secured to a lower surface of the insole and attenuates ground reaction forces as sole  15  is compressed between the foot and the ground, such as during walking or running. Midsole  40  may also absorb energy when compressed. Midsole  40  includes at least one sealed fluid-filled chamber, which will be discussed in detail below. The outsole is the outer surface of the footwear that contacts the ground. Outsole  33  is secured to a lower surface of the midsole and is formed from a durable and abrasion-resistant material (such as rubber) that can be textured to define various protrusions for providing traction. In some embodiments, one or more of the insole and/or outsole are optional. 
     One embodiment of midsole  40  is depicted in  FIGS. 2 a  and 2 b   . As shown, the midsole can include provisions for shock absorption, cushioning, and comfort. Particularly, the midsole can be configured to include rigid hollow support  50  with cavity  41  that can be filled with a plurality of air-filled bladders. The support includes sidewall  42  that extends in an upward direction from lower face  43 . The support includes rear edge  44  that is positioned adjacent to the user&#39;s heel and front edge  45  positioned adjacent to the user&#39;s toe region. The support also includes inner edge  46  positioned adjacent to the inner region (instep) of the user&#39;s foot and opposed outer edge  47  that is configured adjacent to the outer region of the user&#39;s foot. 
     Support  50  can have a thickness  51  of about 0.1-5 inches, as shown in  FIG. 2 b   . The term “thickness” as used herein refers to the longest measurement of the support from top surface  62  to its opposing bottom surface. In some embodiments, the support thickness refers to the height of sidewall  42 . The support can have a thickness at rest of at least about (or no more than about) 0.1, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, 4.25, 4.5, 4.75, or 5 inches. “At rest” refers to the thickness without contact with the wearer&#39;s foot. It should be appreciated that the support thickness is not limited and can be greater or less than the range given herein. 
     In some embodiments, the height of the sidewall is consistent around the entire midsole. In other embodiments, the height of the sidewall can taper from rear edge  44  of the midsole to front edge  45 . For example, the height of the sidewall (e.g., thickness of the midsole) can be about 1 inch at the front edge and about 3 inches at the rear edge. Thus, the midsole sidewall can taper such that the height at the front edge (h 1 ) is about 20-90 percent (e.g., at least/no more than about 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 percent). of the height at the rear edge (h 2 ), as shown in  FIG. 2   c.    
     In some embodiments, the support can be constructed from one or more rigid or semi-rigid materials. The term “rigid” refers to a material that is stiff and not pliable, with a limited degree of flexibility when pressure is applied. The term “semi-rigid” can refer to one or more materials that are stiff and solid, but not inflexible. Suitable rigid and semi-rigid materials can include (but are not limited to) wood, plastic, metal, glass, plexiglass, reinforced cardboard, or combinations thereof. 
     Two or more fluid-filled bladders  55  can be positioned within the cavity of support  50 . One embodiment of bladder  55  is illustrated in  FIG. 3 , although it should be appreciated that the bladders can take any shape. The term “bladder” refers to any container that serves as a reservoir for fluid. The bladder includes exterior surface  60  and interior  61  that is at least partially filled with a fluid. The term “fluid” as used herein refers to any suitable liquid, gas, gel, or combination thereof. Suitable gases can include (but are not limited to) one or more of ambient air, nitrogen, helium, carbon dioxide, etc. Suitable liquids can include (but are not limited to) water, saline, gel, or combinations thereof. The term “gel” refers to a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system that exhibits no flow when in the steady state. The exterior walls of the bladder are sealed to contain the fluid within interior  61 . 
     The bladders can be constructed from polymeric material, rubber, elastomeric material, vinyl, polyurethane, PVA, PLA, fiber-enforced polymer, and the like. The term “elastomeric” refers to a material that can be stretched to at least twice its original length and then retracted to approximately its original length upon release. 
     The interior of bladder  55  can house any desired volume of fluid. For example, each bladder can have an interior volume of about 5-200 cc (cubic centimeters). Thus, the internal volume of the midsole can be at least/no more than about 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 cc. It should be appreciated that the volume of the bladders depends on the size of the midsole (e.g., the size of the user&#39;s foot) as well as the number of bladders present. It should further be appreciated that the midsole can have a volume greater or less than the range given herein. 
     Midsole  40  can include one or more bladders  55  configured with the support cavity. For example, the midsole can include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 bladders. However, it should be appreciated that over 20 bladders can be used. 
     In some variations, all of the bladders are configured to be about the same size and filled to about the same volume. In other variations, at least one bladder  55  varies compared to a second bladder with respect to size, shape, volume, material, fluid, and/or any other characteristic. 
     Optionally, each bladder  55  can include housing  70  that facilitates inflation. The housing can be disposed on any surface of the bladder to allow fluid to be selectively added or removed from interior  61 , as illustrated in  FIG. 4 a   . In operation, a fluid (such as ambient air) passes through the housing into the interior of the bladder. The housing can therefore include a port, valve, plug, aperture, or combinations thereof. In some embodiments, the housing can be a one-way or two-way valve. In some embodiments, the housing can be configured as a check valve that will open when the pressure within the midsole interior is at or greater than a predetermined level. The housing can be accessible in some embodiments through an opening or other access  72  in support  50 , as shown in  FIG. 4 b   . In some embodiments, each bladder includes a housing. However, it should be appreciated that housing  70  is optional and the bladders can be configured without such a feature. 
     A variety of different inflation mechanisms can optionally be utilized with bladder  55 . For example, the inflation mechanism can include a simple bulb that interacts with the housing to add or remove fluid from the bladder interior. Alternatively, a pump (e.g., a handheld pump) can be used to inflate the bladders. 
     In some embodiments, the interior of a bladder can be filled to about 100% maximum volume with a desired fluid. In other embodiments, interior  51  is less than fully filled. For example, bladder can be filled to about 40-100% capacity. Thus, the midsole can be filled to a level of at least about (or no more than about) 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100 percent of the total interior volume of the bladder. In some embodiments, the fluid within the bladder interior can be pressurized between 0-350 kPa (e.g., at least/no more than about 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, or 350 kPa). 
     In some embodiments, bladders  55  can be uniformly arranged within the cavity of support  50 , as shown in  FIG. 5 a   . In other embodiments, the number of bladders, volume, size, and/or degree of fluid fullness can vary depending on the section of the cavity, as shown in  FIG. 5 b   . In some embodiment, adjacent bladders can touch each other along at least one edge, as shown in  FIG. 5 c   . In other embodiments, at least one edge of a bladder can be independent, and not contact another bladder. 
     The bladders can be adhered to the bottom surface of the support cavity using any suitable method, such as adhesive, clips, welding, and the like. In some embodiments, the bladders can be permanently or releasably attached together using any suitable method, such as the use of adhesive. 
     In some embodiments, the height of the filled bladders does not exceed the height of sidewall  42 . In other embodiments, the height of the filled bladders can exceed the height of the sidewall. 
     In some embodiments, the midsole is configured to be about the entire length of the footwear. Thus, the midsole can have length  65  of about 5-16 inches, depending on the size of the wearer&#39;s foot (e.g., at least/no more than about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 inches), as shown in  FIG. 5 a   . However, the length of the midsole is not limited and can be greater or less than the range given herein. 
     Importantly, the midsole lacks an outer covering, such that the bottom of the user&#39;s foot or sock is adjacent to the top surface of the midsole. In some embodiments, the user&#39;s foot or sock directly contacts the bladders of the midsole (e.g., insole  35  is not present). In other embodiments, the insole is present between the midsole and the user&#39;s sock/foot. 
     In some embodiments, the midsole can be used with a separate outsole  33 . In other embodiments, the midsole support functions as the insert outsole, such that no additional outsole is needed. In these embodiments, support  55  acts as the outsole, providing resistance to wear and support on hard surfaces. 
     Advantageously, midsole  40  provides improved shock absorption and running/leaping efficiency compared to prior art midsoles. As described above, a fluid (which can be air at atmospheric pressure) is trapped within the interior of bladders  55 . In use, when a user is standing in the footwear, the fluid in the midsole provides a cushioning effect, as shown in  FIG. 6 a   . However, when the wearer runs or steps, the fluid in the bladders is compressed exclusively from the top-down. Particularly, the heel portion of the outsole (or support  50  if the shoe lacks a separate outsole) first comes into contact with the ground. As a result, the heel of the wearer&#39;s foot exerts a downward pressure on the midsole. The fluid within the bladders in the area of the heel pressure will then be compressed as shown by the arrow in  FIG. 6   b.    
     In response to the compression, the fluid positioned within the interior of the midsole provides a reactive force upon release to give a lifting effect, as the wearer&#39;s weight shifts to the front part of the foot. The reactive force is performed by bladders due to the elastomeric nature of the material used, as shown by the arrows in  FIGS. 6 c  and 6 d   . The reactive force can be exerted on the user&#39;s foot (heel, middle, or ball positions) in the form of a rebound force. Thus, in walking and running (and other movements), the fluid is compressed and then the covering provides the rebound force to give an alternating lifting effect and provide thrust that facilitates walking and running. As a result, the midsole provides improved shock absorption and allows the wearer greater mobility when running, leaping, etc. 
     Although midsole  40  may be especially advantageous when used with athletic shoes, the presently disclosed subject matter is not limited and the midsole can be used with any type of footwear. 
     The disclosed midsole therefore provides for a unique top-bottom compression, enabled by the elastomeric bladders  55 . As a result, the reactive force that occurs after compression provides a benefit to the wearer in the form of a burst of compression release. 
     The disclosed midsole is simple to manufacture and can be easily used with existing footwear. 
     Advantageously, the disclosed midsole is of simple and clean design, and can lack foam, rubber, and other malleable material in some embodiments. 
     In some embodiments, the midsole can be used alone (e.g., without an outsole and/or insole). 
     The disclosed midsole results in negligible impact forces being felt by the user during high impact activities, such as running and jumping. When the wearer exerts force upon midsole, the action will compress the fluid in the bladders. However, since the bladders are placed in the rigid cavity of the support, they have nowhere to go, giving a rebounding effect to the wearer. This also means the force interactions are isolated to the person and the air molecules. The impact from the ground is not felt by the wearer. Running would feel as gentle as jumping on an inflatable. 
     Advantageously, the support  50  creates a rigid cavity that acts as a foundation for the one or more fluid-filled bladders. As opposed to traditional designs where air is inserted into the sole of a sneaker or other item of footwear, the disclosed midsole provides for improved cushioning and impact reduction. Specifically, the user&#39;s foot is in direct contact (the foot or sock contacts the bladders) or indirect contact (an upper is present between the midsole and the user&#39;s foot or sock) with the fluid-filled bladders. 
     The presently disclosed subject matter is disclosed above and in the accompanying drawings with reference to a variety of embodiments. The purpose served by the disclosure, however, is to provide an example of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications can be made to the embodiments described above without departing from the scope of the present invention, as defined by the appended claims.