US 20040211087 A1
Improved impact cushioning within a shoe is provided by a novel heel hammock recess formed beneath the heel of the wearer. The heel hammock recess includes an elastic member supporting the wearer's heel surrounded by a surround surface formed to bear substantial weight. The impact energy transmitted upwardly through the heel to the wearer's foot during heel impact passes through the elastic membrane of the heel hammock allowing flexing and energy absorption to occur as the heel is cradled in the heel hammock. Embodiments are shown in which the impact absorbing member is formed integrally with a molded athletic shoe sole as well as alternative embodiments in which the impact absorbing structure is formed in a removable insole and also formed in a variety of general use shoes.
1. A shoe comprising:
a sole having a top surface a bottom surface and a heel portion;
an upper joined to said sole, said upper and said sole top surface forming a foot-receiving cavity in which said wearer's heel rests upon said heel portion; and
a recess formed in said heel portion having an elastic membrane in said top surface, a surround surface in said bottom surface and a sidewall extending therebetween.
2. The shoe set forth in
3. The shoe set forth in
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10. A shoe comprising:
a foot-receiving member including a heel support;
a cushion within said foot-receiving member; and
a recess formed in said cushion at said heel support, said recess including a surround surface, an upwardly extending sidewall and an elastic membrane spanning the upper portion of said recess.
11. The shoe set forth in
12. The shoe set forth in
13. An insole for use in combination with a shoe having a heel supporting portion, said insole having a recess formed in said cushion at said heel support, said recess including a surround surface, an upwardly extending sidewall and an elastic membrane spanning the upper portion of said recess.
 This invention relates generally to shoes and other footwear and particularly to the impact and shock absorption provided therein. The invention relates to athletic shoes, general use footwear, dress shoes (both men's and women's) and may be utilized in an integrally formed sole structure or in a removable insole structure.
 Shoes worn for various human athletic endeavors are well known in the art and used extensively. As with other forms of athletic gear and apparel, attention is given to the particular needs of the sport or activity. Thus, athletic shoes are often specialized in design for various athletic activities such as running, jogging, walking, baseball, American football, soccer football and so on. Not surprisingly, this broad spectrum of specialized use has provided a virtually endless variety of athletic shoe designs and structures.
 Despite this extensive variation, such athletic shoes may generally be described as employing the same combination of basic elements. For example, virtually all athletic shoes utilize a sole supporting a tread on its bottom surface and a foot supporting cushion upper surface. In addition, a foot-receiving shoe upper is secured to the sole by various fabrication techniques. Finally, a closure device such as straps or laces is utilized to facilitate the placement of the wearer's foot within the foot-receiving upper and thereafter securing the foot therein.
 While a substantial number of considerations and design characteristics apply to each and every portion of the basic athletic shoe, some generalizations may be made. By way of example, the foot-receiving upper is maximally designed to provide wearing comfort, flexible support together with adequate ventilation or so-called “foot breathing”. Similarly, the closure apparatus utilized is designed to maximize security, comfort and ease of use. Further, the sole portion of the shoe is also fabricated with the objective of providing comfort together with other considerations such as impact cushioning or energy absorption as well as flexibility. Finally, the tread selected for the bottom surface of the sole is designed to maximize surface gripping or traction as well as wear qualities and impact cushioning.
 Many of the design perimeters of athletic shoes are determined by the complex method found in human activity such as walking, jogging and running. In all such activities, the human process for travel involves a complex rhythmic and repetitive process of striding and thrusting operations.
 Basically, this complex human movement can be broken down into a series of repetitive operations or actions. Thus, as one leg and foot engage the ground and thrust the human forward, the alternate foot and leg stride forwardly through the air. As the thrust of the thrusting leg and foot is completed, the foot of the striding leg and foot is driven downwardly to meet the ground and begins assuming the body weight. As the thrusting leg and foot complete the thrust action, the foot is lifted and brought forward transitioning to a forward striding motion. Simultaneously, the body moves forward over the leg and foot of the now weight supporting striding leg and foot. As the body continues forward, the striding leg and foot transitions to a thrusting movement.
 As the striding and thrusting process is repeated, each foot undergoes a substantial impact when acting as the striding foot and when being driven downwardly to impact the ground under body and weight and forward momentum. As the body weight is transferred to the striding foot, the impact is generally absorbed in a “heels first” impact. The foot then rolls from heel to full foot and thereafter to toe support as it moves from striding impact through the thrusting action.
 While all of the above design considerations are important during the running, jogging or walking cycle, each foot repeatedly forms striding impact, full foot support and thrusting, certain design aspects become more critical than others during the cycle portions. For example, during the striding impact, the degree of energy absorbing cushioning provided to the foot with particular attention to the heel portion thereof becomes temporarily most critical. Similarly, during the full foot body weight support of the cycle characteristics such as cushioning and traction become maximally important. Finally, during the thrusting action of the cycle, flexibility and traction become paramount characteristics.
 Throughout the rolling motion of the foot, flexibility of the sole and tread as well as the foot upper remain critical elements of shoe design. Often the competing characteristics of one need such as cushioning may compete with or require compromise with another characteristic such as traction or flexibility. Thus, the full design of an athletic shoe structure is by its nature a generally complex undertaking.
 Prior art devices directed toward protecting the foot of a shoe wearer have, for the most part, relied upon the use of energy-absorbing compressible materials such as resilient foam or the like. This use of compression based materials often results in substantial energy of impact being imparted to the shoe wearer's heel. This results from the non-linear characteristic of compressible materials (ie. they often “bottom out”) and the general wear and loss of resilience which they exhibit.
 With respect to footwear generally, as distinguished from athletic wear, it will be noted that the above described problems and design considerations are not limited to athletic shoes. Rather, these principles and considerations apply in varying degrees virtually all footwear. The greater stresses imposed upon the human foot during athletic activity such as running, jogging or walking do not render these design considerations and structures of footwear set forth above exclusive to athletic footwear. However, the above considerations become substantially more imperative and critical in athletic footwear than general foot apparel. It will be apparent however that the inventive structure found in the present invention as described and set forth below can readily be understood to all footwear generally with particular advantage in athletic footwear. It will be equally important that the present invention impact absorbing structure may be integrally formed in virtually any type of shoe or may be formed as a removable insole for various shoes.
 Because of the ever continuing need to provide more effective footwear for both general use and athletic activities, there arises a continuing need in the art for evermore improved footwear structures.
 Accordingly, it is a general object of the present invention to provide an improved shoe having improved impact absorption. It is a more particular object of the present invention to provide an improved shoe having improved impact absorption which more effectively meets the demanding needs and requirements found in shoes intended for athletic activity as well as shoes used as more general footwear. It is a still more particular object of the present invention to provide an improved shoe having improved impact absorption which does not rely upon compressible materials but instead more effectively protects the heel portion of the foot as the striding foot of the wearer impacts the ground and assumes body weight through the use of a resilient heel hammock which effectively cradles the wearer's heel.
 In accordance with the present invention there is provided a shoe comprising: a sole having a top surface a bottom surface and a heel portion; an upper joined to the sole, the upper and the sole top surface forming a foot-receiving cavity in which the wearer's heel rests upon the heel portion; and an impact absorbing recess formed in the heel portion having an elastic membrane in the top surface, a surround surface in the bottom surface and a sidewall extending therebetween.
 From another perspective, the invention provides a shoe comprising: a foot-receiving member including a heel support; a cushion within the foot-receiving member; and an impact absorbing recess formed in the heel support, the impact absorbing recess including a surrounding surface, an upwardly extending sidewall and an elastic membrane spanning the upper portion of the impact absorbing recess.
 The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements and in which:
FIG. 1 sets forth a perspective view of an improved athletic shoe constructed in accordance with the present invention;
FIG. 2 sets forth a top view of the present invention athletic shoe;
FIG. 3 sets forth a bottom view of the present invention athletic shoe;
FIG. 4 sets forth a side elevation view of the present invention athletic shoe;
FIG. 5 sets forth a section view of the present invention athletic shoe taken along section lines 5-5 in FIG. 2;
FIG. 6 sets forth an enlarged partial section view of the rear portion of the present invention athletic shoe showing an illustrative human foot portion in phantom line depiction therein;
FIG. 7 sets forth a partial view of an illustrative conventional article of footwear having the present invention impact absorbing mechanism therein;
FIG. 8 sets forth a partial section view of a further embodiment of the present invention impact absorbing shoe;
FIG. 9 sets forth a top view of an insole utilizing a further alternate embodiment of the present invention impact absorbing mechanism;
FIG. 10 sets forth a partial section view of a still further alternate embodiment of the present invention shoe; and
FIG. 11 sets forth a top plan view of an insole having a still further alternate embodiment of the present invention impact absorbing shoe.
FIG. 1 sets forth a perspective view of an athletic shoe constructed in accordance with the present invention and generally referenced by numeral 10. Athletic shoe 10 includes an upper portion 11 fabricated generally in accordance with conventional fabrication techniques defining a foot-receiving portion 12 and supporting a plurality of mesh vent portions 20, 21 and 22 (mesh portion 22 shown in FIG. 2). Shoe 10 further includes a sole 13 formed of a molded rubber material or the like and defining a tread portion 14 on the bottom surface thereof. Sole 13 further includes a heel portion 15 and an inlay of flexible material 25 therebetween. Flexible portion 25 is preferably formed of a material more flexible than the material forming sole 13 and heel 15. Vent portions 20, 21, and 22 are preferably formed of a mesh material allowing air transfer therethrough. The function of mesh portions 20, 21 and 22 is to provide sufficient “foot breathing” to allow a more comfortable experience for the wearer of shoe 10. Shoe 10 further includes an angular extending strap 16. Strap 16 includes a conventional buckle and angularly extends downwardly from one side of upper 11 and forwardly toward sole 13. The function of closure strap 16 is to provide secure attachment of upper 11 to the wearer's foot in an attachment which substantially improves the fit of shoe 10.
FIG. 2 sets forth a top view of shoe 10. As described above, shoe 10 includes a sole 13 having a heel portion 15. Shoe 10 further includes an upper 11 having mesh vent portions 20, 21 and 22 formed thereon. A foot receptacle 12 is formed in upper 11 and is provided with closure by a downwardly and forwardly extending strap 16. Sole 13 further defines upwardly extending ankle supports 18 and 19 which are sufficiently firm to add support to the wearer's ankles.
FIG. 3 sets forth a bottom view of shoe 10. As described above, shoe 10 includes a sole 13 formed of a molded rubber material and the like and defining a thread 14. Thread 14 further includes a simulated animal paw print shaped member 17. Sole 13 further includes a heel portion 15. In accordance with an important aspect of the present invention, heel portion 15 defines a recess 30 formed by a sidewall 31 and a surrounding surface 32. The upper portion of recess 30 defines an elastic membrane 33 supporting an indicia 34. As is set forth below in greater detail, recess 30 and elastic membrane 33 cooperate to form an impact absorbing “heel hammock” which cradles and protects the wearer's heel, particularly during foot impact.
 This heel hammock operation of recess 30 and membrane 33 in accordance with the present invention is described below in greater detail. However, suffice it to note here that recess 30 operates to distribute impact forces to surrounding surface 32 as elastic membrane 33 flexes in an energy absorbing fashion in an action much like a hammock supports weight. This heel hammock supports the wearer's heel in a cradle-like support avoiding the energy transfer of a compressible cushion. Indicia 34 provides a further enhancement of the present invention recess and, may for example, contain a personalized indicia or alternatively a trademark indicia for the manufacturer of the shoe.
FIG. 4 sets forth a side elevation view of the present invention shoe showing upper portion 11 having mesh vent portions 20 and 21 together with an angularly forwardly extending strap 16. Shoe 10 further includes a sole 13 having a tread 14 formed on the underside thereof together with a heel portion 15. Heel 15 further defines a surrounding surface 32 which, as described below in greater detail, generally encircles a cushion recess 30 (seen in FIG. 3). Sole 13 further includes a more flexible portion 25 positioned forwardly of heel portion 15. The function of flexible portion 25 is to provide a higher flexibility region within sole 13 allowing sole 13 to flex more easily to improve the wearer's comfort.
FIG. 5 sets forth a section view of shoe 10 taken along section lines 5-5 in FIG. 2.
 As described above, shoe 10 includes an upper portion 11 supported by a sole 13 upon which a tread 14 is formed. As is also described above, sole 13 includes a heel portion 15 defining a recess 30 and a sidewall 31. At the upper portion of recess 30, an elastic membrane 33 is formed which supports an optional indicia 35. In the preferred fabrication of the present invention, sole 13 including tread 14 and elastic membrane 33 together with surrounding surface 32 are formed as a single molded rubber portion.
 In addition to the above described structure, shoe 10 further includes a cavity 26 formed within sole 13 and extending generally the length and width of sole 13. Within cavity 26, an elastic gel material 27 is captivated. In accordance with the preferred fabrication of the present invention, elastic gel 27 occupies a portion of cavity 26 but not its entirety. Thus, with the wearer's foot positioned within shoe 10 and with shoe 10 supporting weight upon the wearer's foot, cavity 26 is deformed displacing and exerting upon elastic gel 27. Elastic gel 27 disperses to more fully occupy cavity 26 in response to the downward force of the wearer's foot upon sole 13. In the preferred fabrication of the present invention, elastic gel 27 provides a viscous material which is able to resist flow to some extent but which is completely deformable. Further, elastic gel 27 is further selected to provide a characteristic by which the gel tends to collect.
 Accordingly, elastic gel 27 may, for example, comprise a viscous plastic or rubber gel. Alternatively, elastic gel 27 may utilize a silicone gel similar to that used in breast implants having a selected viscosity. Gel 27 may also employ a material which is not elastic in its properties but is instead extremely viscous such as viscous oil or the like. The important aspect in selecting the property of gel 27 is found in its ability to absorb impact or force energy exerted downwardly upon sole 13 by the user and to absorb the force or impact thereon by displacement of gel 27 rather than compression. For purposes of discussion in the remaining material, gel 27 will be referred to as “elastic gel”. However, it will be understood that gel 27 need not posses elastic characteristics but rather may also utilize a viscous gel which in the cooperating reservoir exhibits an elastic quality. In further accordance with the present invention, the energy or impact absorbing qualities of shoe 10 are further enhanced by the functioning of recess 30 together with elastic membrane 33 to provide the above-mentioned heel hammock support. In accordance with an important advantage of the present invention shoe, impact energy imparted to heel portion 15 of shoe 10 by the wearer is absorbed by a dual mechanism of elastic gel 27 and the heel hammock elastic membrane 33. However, either mechanism operating separately also provides important advantages in accordance with the present invention. The important quality provided by the present invention is absorption of the shock of impact.
 With respect to the operation of recess 30, the extension of sidewall 31 upwardly and the position of surrounding surface 32 cause impact against the ground as heel portion 15 impacts the ground to be further absorbed by the stretching of elastic membrane 33 as it cradles the heel. Accordingly, the position of recess 30 and elastic membrane 33 is carefully chosen to position elastic membrane 33 beneath the heel bone of the wearer allowing the flexing membrane to support and protectively cradle the heel as the membrane stretches and flexes around the heel. This additional impact absorption is particularly advantageous due to the very substantial amount of energy normally absorbed by the user's heel during activity.
FIG. 6 sets forth an enlarged partial section view of the present invention shoe together with a phantom line depiction of a typical wearer's foot and heel bone. As described above, shoe 10 includes an upper portion 11 secured to a supporting sole 13. As is also described above, sole 13 defines an extended cavity 26 within which a quantity of elastic or viscous gel 27 is captivated. Sole 13 further includes a heel portion 15 having a recess 30 formed therein. Recess 30 includes a sidewall 31 and a surrounding surface 32. Recess 30 further defines a relatively thin elastic membrane 33 supporting an optional visual indicia 34. A typical foot 40 having a typical heel bone 41 is depicted within FIG. 6 to illustrate the relative positioning of heel bone 41 and recess 30 for a typical wearer of shoe 10. As can be seen, heel bone 41 which normally provides substantial impact as foot 40 is driven downwardly to impact the ground is generally supported by elastic member 33 and surrounding surface 32. Thus, as the user strides forward during walking, running or jogging and heel 15 impacts the ground, the force applied to heel bone 41 of foot 40 is greatly absorbed by the stretching of elastic surface 33 as it forms a hammock support. In essence, the impact is transmitted directly from the ground to surrounding surface 32 of heel 15. Thereafter, the substantially thicker and therefore less flexible portions of sole 13 deflect a relatively small amount. Conversely, the relatively thin portions of elastic membrane 33 stretch a substantial distance downwardly supporting the heel and absorbing the impact felt by heel bone 41. The extent of downward deflection facilitated by elastic membrane 33 is determined for the most part by the depth of recess 30 and the elasticity of membrane 33. Additional impact absorption is, as described above, provided by gel 27 within cavity 26.
 The combined impact absorbing effect of recess 30 together with gel 27 within cavity 26 provides a substantial reduction in the impact force felt by heel bone 41 of foot 40. In this manner, a great improvement in the impact absorption for the wearer's foot results in a reduced likelihood of injury and less wear and tear on the users foot.
FIG. 7 sets forth an alternate embodiment of the present invention shoe generally referenced by numeral 50. Shoe 50 is a conventional “high heel” of the type typically worn by women. However, it will be apparent to those skilled in the art from the descriptions which follow that the high heel structure of shoe 50 is selected for illustration purposes and that the present invention embodiment shown in FIG. 7 is not limited to any particular type of shoe. Thus, shoe 50 may be constructed in accordance with conventional fabrication techniques and includes an upper portion 51 supported by a sole 52 and a heel 53. In accordance with the present invention, FIG. 7 also shows an insole generally referenced by numeral 60. Insole 60 is fabricated of a cushioning material such as rubber, foam plastic or the like and is shaped to be received within the interior of shoe 50 and to be conveniently positioned upon the upper surface of sole 52. Insole 60 includes a recess 61 having a sidewall 62 and an elastic membrane 63 formed therein. Recess 21 including sidewall 62 and elastic membrane 63 function in the same manner as cushion recess 30, sidewall 31 and elastic membrane 33 shown in shoe 10 (seen for example in FIG. 3). The fundamental difference between the embodiment shown in FIG. 7 and generally referenced as insole 60 and the embodiment shown in FIGS. 1 through 6 is the provision of a removable insole which contains the present invention structure for a heel hammock impact absorbing recess. Thus, insole 60 is removable from shoe 50 and may be placed within a variety of different shoes. Conversely, recess 30 shown in shoe 10 in FIGS. 1 through 6 is formed integrally with the sole of shoe 10 (see for example FIG. 6).
 Insole 60 having recess 61 functions in the same cushioning and impact absorbing manner described above. Fundamentally, the positioning of recess 61 and elastic membrane 63 beneath the heel supporting portion of the host shoe 50 ensures that the wearer's heel bone shown in phantom line depiction 70 is supported in a cradle-like support by elastic membrane 63. Upon impact as the wearer strides forward and heel 53 is brought into contact with the ground surface elastic membrane 63 flexes downwardly within recess 61 absorbing energy and cushioning the impact communicated from heel 53 to heel bone 70 of the wearer's foot. Once the force has been absorbed during impact, and the users weight remains upon the foot within shoe 50, elastic membrane 63 returns to a somewhat more normal shape as shown in FIG. 7. However, it will be understood that the continued load of a portion of the wearer's weight upon insole 60 will cause some downward flexing of elastic membrane 63. Thus, the material selected for insole 60 such as molded rubber or plastic or other elastic material is selected with some consideration for the users anticipated weight and with some consideration for the thickness of elastic membrane 63 to be formed.
FIG. 8 sets forth a partial section view of an alternate embodiment of the present invention impact absorbing shoe generally referenced by numeral 80. Shoe 80 will be understood to be illustrative of virtually any shoe whether for general or athletic use. Shoe 80 includes an outsole 81 defining a recess 82 in the heel portion thereof. An insole 83 may be either formed integrally within shoe 80 or be a removable insole as desired. Insole 83 spans recess 82 within the interior of upper 85 of shoe 80. Insole 83 further defines a lower durameter or more elastic portion 85. Portion 85 may be fabricated by attachment to insole 83 using conventional attachment such as sonic or adhesive attachment or the like. The important function of portion 84 is to provide a flexible membrane spanning recess 82 to provide the above-described heel hammock which cradles the heel of the wearer's foot under impact. The mechanism by which the embodiment of FIG. 8 functions is substantially identical to that described above as under impact the user's heel stretches portion 84 downwardly into recess 82 to provide impact absorption.
FIG. 9 sets forth a top plan view of an insole constructed in accordance with a still further alternate embodiment of the present invention and generally referenced by numeral 90. Insole 90 may be a removable insole capable of being moved to and from a host shoe or, alternatively, may be integrally formed as the permanent insole of a shoe. Insole 90 defines an aperture 91 together with a mesh membrane 92 spanning aperture 91. Mesh membrane 92 provides the above-described flexible elastic covering for a recess within the host shoe. In this manner, mesh membrane 92 functions to provide the impact absorbing cradling effect which, in accordance with the present invention, protects the heel of a shoe wearer during impact.
FIG. 10 sets forth a partial section view of a still further alternate embodiment of the present invention shoe generally referenced by numeral 95. Shoe 95 will be understood to be illustrative of virtually any type of shoe whether general or athletic use or the like. Shoe 95 includes an outsole 96 within which a recess 97 is formed in the heel portion thereof. An insole 98 is supported within shoe 95 and may be permanently secured or removable as desired. Of importance with respect to the present invention is a thinner membrane portion 99 formed integrally with insole 98 which is generally aligned with and which generally spans recess 97. The cooperation of thinner membrane 99 and recess 97 provides the above-described flexing under impact to protect the wearer's heel in the heel hammock and cradling effect described above.
FIG. 11 sets forth a top view of a still further alternate embodiment of the present invention impact absorbing shoe. FIG. 11 shows an insole generally referenced by numeral 100 configured to be received within the interior of a host shoe (not shown). Insole 100 may be permanently secured within the host shoe or removable as desired. Insole 100 is generally planar and defines a first cavity 101 positioned upon insole 100 to generally lie beneath the ball of the wearer's foot. Insole 100 further includes a second cavity 102 generally positioned upon insole 100 to lie beneath the heel of the wearer's foot. Cavities 101 and 102 are connected by a transfer passage 103. A quantity of viscous gel 104 is supported within a portion of cavity 101 while a second quantity of gel 105 is supported within a portion of cavity 102. It will be noted that gel portions 104 and 105 do not fully occupy cavities 101 and 102 respectively. The embodiment of the present invention shown in FIG. 1 utilizes the size of transfer passage 103 and the viscosity of gel within cavities 101 and 102 to provide an impact absorption as the wearer's foot impacts either cavity. For example, in the event of a heel impact, the wearer's heel imparts a force to cavity 102 displacing gel 105 through transfer passage 103 in the direction indicated by arrow 107 causing the viscous gel to flow into cavity 101. The partial filling of cavity 101 allows the additional gel to be transferred thereto. This gel transfer and the viscosity of the gel cooperating with the size (resistance to gel flow) of transfer passage 103 combine to absorb the energy of heel impact.
 Conversely, when the wearer encounters an impact to the ball of the wearer's foot, a displacement of gel 104 within cavity 101 through passage 103 in the direction of arrow 106 occurs. The transferred gel is displaced through passage 103 into cavity 102 in the direction indicated by arrow 106 combining with gel quantity 105. Thus, the operation of insole 100 utilizes the restricted flow resistance of passage 103 between cavities 101 and 102 to cause energy to be absorbed as the respective gel quantities are displaced due to foot impact upon the insole.
 What has been shown in a novel shoe having improved impact absorption and an alternate embodiment thereof in which a removable insole having impact absorption fabricated in accordance with the present invention is provided. The novel aspects of the invention include the provision of a recess within the heel portion of the shoe or insole together with an elastic membrane upon which the heel bore impact of the wearer's movement is dissipated as the member flexes. The inventive impact absorbing structure may be incorporated as an integral part of a molded shoe sole such as that found in athletic shoes or alternatively may be fabricated within a removable insole for use in a number of different shoes. The invention further provides a cavity formed within the sole of a shoe within which a gel such as an elastic material gel or a highly viscous gel is captivated in a quantity less than the full capacity of the cavity. This facilitates the viscous or elastic movement of the gel material under load within the cavity to provide a novel impact absorbing effect.
 While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.