Patent Publication Number: US-8539697-B2

Title: Suspension heel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Design application Ser. No. 29/376,693, filed on Oct. 11, 2010, now pending, and claims the benefit of the filing date of U.S. Provisional Patent Application No. 61/391,797 filed Oct. 11, 2010, the entire disclosures of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to footwear. More particularly, the present invention relates to a suspension system that supplies enhanced cushioning in high heeled footwear. 
     2. Description of Related Art 
     High heels are a very popular footwear choice due to their elegant style and increase in virtual height of the wearer. However, certain challenges relating to high-heeled footwear exist for both the consumer and manufacturer. Despite their popularity, high-heeled shoes require a certain set of skills to wear effectively without losing stability or falling down. Moreover, there typically is a loss of comfort as compared with flat-soled shoes. For instance, the foot is positioned at an awkward angle for sustained periods of time with the toes pointed in a plantarflexion position. 
     The shock absorbing qualities of such high-heeled footwear can be extremely poor. In the construction of a typical high-heeled shoe, the attachment of the heel component to the sole of the shoe may require a very rigid connection in order to keep the heel component from moving fore and aft or side to side during a normal walking gait. The possibility for such movement is high because of the large lever that the elongated heel creates. With all of the forces focused on the distal end of the heel, a large torque is placed on the point where the heel component meets the shoe sole. A non-rigid connection can quickly deteriorate. In this case, the heel would eventually detach from the shoe sole. 
     While a rigid connection provides needed durability, it negatively impacts the shoe&#39;s ability to cushion the user from the ground. Given that cushioning and protection from the ground are primary functions of footwear, the inclusion of a stiff, high-heeled shoe can detract from one of the fundamental purposes of footwear. 
     The benefits of style and the increase in virtual height for the wearer are often desirable enough for the user to overlook the discomfort often found in many high heel shoes. However, daily episodes of wearing high-heeled shoes that provide sub-par cushioning can lead to long term disabilities including back injuries, joint discomfort, bunions, heel spurs, and other foot injuries. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the disadvantages of conventional high-heeled footwear by providing compliance where the heel meets the ground. This provides much needed cushioning to the wearer. Importantly, this is accomplished while allowing the user to retain beneficial qualities of a high-heeled shoe such as style, a rigid connection between the heel and sole, and stability. 
     As will be explained in more detail below, aspects of the invention provide for this compliance through a combination of features. Compliance in the vertical direction, in order to provide cushioning, absorbs the ground reaction force by straining a compliant material. Compliance is further created via a rolling action in the gait and increased surface area contact between a compliant heel plug and the ground. The rolling action as the wearer walks helps to distribute contact forces and keeps those forces from transmitting up through the heel of the shoe and into the wearer&#39;s body. 
     An article of footwear, comprising a sole, an upper and a suspension heel member. The sole has a first surface for supporting a wearer&#39;s foot and a second surface remote from the first surface. The upper connected to the sole. And the suspension heel member includes a heel shaft having a first end connected to the second surface of the sole, and a second distal end remote from the first end. The distal end of the heel shaft has a heel cavity therein. The suspension heel member also includes a compliant heel plug having a base section for contacting the ground and a connecting section attached to the base section and being adapted to fit within the cavity of the distal end of the heel shaft. The compliant heel plug and the distal end of the heel shaft form a relief detail for providing force attenuation to the wearer. 
     In one example, the base section of the compliant heel plug includes anterior and posterior regions, and the posterior region includes a curved surface with a predefined radius for providing a rolling action when contacting the ground during use of the article of footwear. 
     Attenuating the amount of force transmitted through an article of footwear by providing an article of footwear with a sole, an upper connected to a first surface of the sole, and a suspension heel, having a heel shaft and a compliant heel plug rigidly affixed to interior sidewalls of a cavity in the heel shaft, connected to a second surface of the sole. Flexing a base section and a partially exposed connecting section of the compliant heel plug upon application of force to the upper or the compliant heel plug. Decreasing the contact forces transmitted through the article of footwear that are created when the compliant heel plug strikes a surface, in comparison to a traditional heel, by providing a curved posterior section of the compliant heel plug to create a greater contact surface area and a rolling action. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-C  illustrates views of a high-heeled shoe in accordance with aspects of the invention. 
         FIG. 2  is an exploded side view that illustrates the elements of the high-heeled shoe of  FIG. 1A . 
         FIG. 3  illustrates a perspective view of a compliant heel plug of  FIG. 2  separated from a high heel cavity. 
         FIGS. 4A-B  illustrate cutaway views of a compliant heel plug in accordance with aspects of the invention. 
         FIG. 5  illustrates a top view of a compliant heel plug in accordance with aspects of the invention. 
         FIG. 6  illustrates is a cutaway view of a suspension heel in accordance with aspects of the invention. 
         FIGS. 7A-B  illustrate a relief detail in unloaded and loaded phases in accordance with aspects of the invention. 
         FIGS. 7C-D  illustrate alternative relief detail arrangements in accordance with aspects of the invention. 
         FIG. 8  illustrates aspects of a compliant heel plug in accordance with aspects of the invention. 
         FIGS. 9A-B  illustrate compression of relief detail spacing in accordance with aspects of the invention. 
         FIGS. 10A-E  illustrate different views of one embodiment of the suspension heel in accordance with aspects of the invention. 
         FIGS. 11A-E  illustrate different views of an alternate embodiment of the suspension heel in accordance with aspects of the invention. 
     
    
    
     The features shown in the figures are not drawn to scale. 
     DETAILED DESCRIPTION 
     In describing preferred embodiments of the invention illustrated in the appended drawings, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. While the illustrated embodiments present a suspension heel architecture that is desirably used in a high-heeled shoe, one skilled in the art would recognize that aspects of the invention may be employed with other types of footwear including, but not limited to, low-heeled shoes or boots. 
       FIGS. 1A-B  are side views illustrate an article of footwear  10  that utilizes a suspension heel architecture according to aspects of the invention.  FIG. 1C  is a bottom view of the article of footwear  10 . The article of footwear  10  includes a sole  12 , heel member  14  and upper  16 . The upper  16  is omitted in the illustration of  FIG. 1B . The upper  16  of  FIG. 1A  presents an open-toe configuration, although those skilled in the art would recognize that other embodiments, such as closed-toe or boot configurations, may also be employed. Here, the upper  16  may include one or more forefoot straps  18  that connect to the sole  12 , and an ankle strap  20  that is secured to one of the forefoot straps  18 . 
     Turning to  FIG. 1B , the sole  12  may comprise an outsole  22  and an insole/midsole  24 . Outsole  22  and the insole/midsole  24  may comprise any types of conventional soles suitable for use with a high-heeled shoe. The outsole may include a tread pattern in the forefoot region for traction and stability, as illustrated in  FIG. 1C . The heel member  14  that forms a suspension heel includes a heel shaft  26  and compliant heel plug  28 . Heel shaft  26  may be rigidly secured to the heel portion of outsole  22 . For example, the heel may be fastened to the outsole  22  using adhesives, tacks, screws or other fastening means. As will be explained in more detail below, compliant heel plug  28  is firmly affixed to heel shaft  26  while providing cushioning and significantly attenuating the ground reaction force. 
     The heel shaft  26  can be made from a variety of materials. In one example, the heel shaft  26  is formed with an injection molded ABS-type plastic. Other materials include, but are not limited to, wood (such as hard woods, recycled wood), other rigid materials, and combinations thereof. 
     The compliant heel plug  28  may also be made from a variety of materials, so long as they are compliant or otherwise elastic-type materials that strain/compress when a force is applied. For instance, injected, compressed and thermoplastic rubbers are all suitable for use as the compliant heel plug  28 . The compliant heel plug may also be formed from a composite of materials such as a combination of foam and rubber or foam and plastic. 
       FIG. 2  illustrates an exploded side view of the high-heeled shoe  10  with heel member  14  detached from both outsole  22  and compliant heel plug  28 . As shown, the compliant heel plug  28  includes a base section  30  and a connecting section  32 .  FIG. 3  illustrates an exploded perspective view of the heel shaft  26  separated from the compliant heel plug  28 . As shown in this view, the distal end of heel shaft  26  includes a heel cavity  34  for accepting the connecting section  32  of the compliant heel plug  28 . Depending on the configuration of the heel shaft  26 , the heel cavity  34  may be formed as a molded cavity. 
     The heel cavity  34  includes interior sidewalls  36  and end surface  38 . As shown in the side and top cutaway views of  FIGS. 4A and 4B , the heel shaft  26  may include one or more holes or open regions  40 . These open regions  40  desirably extend along the shaft to the end surface  38 . The diameters of the open regions  40  may be on the order of 5-10 mm, by way of example. 
     As shown in  FIG. 5 , the connecting section  32  of the compliant heel plug  28  may include one or more open regions  42  therealong. The open regions  42  are separated by spacers  44 , which desirably extend from an upper surface of the connecting section  32  to the base section  30 . The connecting section  32  also includes an exterior surface  46  sized to fit snugly inside receptacle of the heel cavity  34 . 
     The cutaway view of  FIG. 6 , taken along the anterior section of the heel member  14 , illustrates that, when assembled, the exterior surface  46  of the connecting section  32  adjoins the interior sidewalls  36  of the heel cavity  34 . The exterior surface  46  is configured to snugly fit within the interior sidewalls  36 . As shown, the exterior surface  46  may narrow or slope (taper) from the base section  30  toward the end surface  38  of the heel cavity  34 . This frustoconical or pyramidal-type tapering may be on the order of 1-10 degrees. There is generally a small draft angle of, e.g., 1-5 degrees, to ensure that the part comes out of the mold correctly. Other angles may be used for aesthetic purposes. 
     The compliant heel plug  28  is desirably affixed to the heel cavity by adhering the exterior surface  46  to the interior sidewalls  36 . The upper portions of the spacers  44  may also be adhered to the end surface  38 . 
     As shown in  FIG. 6 , a relief detail  48  is provided between the base of the heel shaft  26  and the base section  30  of the compliant heel plug  28 . The relief detail  48  provides spacing between the base section  30  of the compliant heel plug  28  and heel member  14 . The relief detail  48  desirably circumscribes the entirety of the heel member  14 . It may be formed due to the tapering configuration of the exterior surface  46  of the connecting section  32 . The relief detail  48  allows the lower region of the compliant heel plug  28 , such as the base section  30  and the portion of the connecting section exposed by the relief detail  48  to flex and deliver desired force attenuation to the wearer. 
     The enlarged views of  FIGS. 7A and 7B  illustrate how the compliant heel plug  28  provides vertical compliance to the shoe  10 . In the scenario of  FIG. 7A , assume that the shoe is at rest on the ground without force being applied. In this situation, the relief detail spacing is at its maximum value. Here, the relief detail spacing on the anterior side (RD H1 ) is desirably equivalent to the relief detail spacing on the posterior side (RD H2 ), although this is not required. Similarly, the relief detail spacing along the medial and lateral sides may also be the same size. 
     In a preferred embodiment, the relief detail spacing in an unloaded or uncompressed state is substantially uniform about the anterior, posterior, medial and lateral regions. In one example, the spacing of the relief detail in an unloaded or uncompressed state is on the order of 5.0 mm. In another example, the spacing of the relief detail in the uncompressed state may be between 3.0-7.0 mm. In a further example, the spacing of the relief detail in the uncompressed state may be at least 1.5 mm. In yet another example, the spacing of the relief detail in the uncompressed state is no more than 10.0 mm. 
     In another embodiment, the relief detail need not fully circumscribe the heel. For instance, one could have the anterior portion flush to or connected with the heel and the other three sides with a relief detail. This would provide cushioning upon heel strike and enhanced stability when the weight of the wearer is evenly distributed across the shoe. This is shown in  FIG. 7C , where the heel member  14  includes anterior portion  50  without the relief detail. The anterior portion  50  may be part of compliant heel plug  28 , heel shaft  26 , or may be part of both components. And  FIG. 7D  shows a variation that includes multiple anterior portions  52 , which also provide the aforementioned benefits. 
     The particular spacing may vary depending upon the amount of shock attenuation and/or style desired. Larger relief detail spacing would allow for greater vertical compliance than smaller relief detail spacing. In one scenario, the relief detail spacing may vary depending on the type/style of high heeled shoe. For instance, a shoe marketed as the most comfortable high heeled shoe might have a larger relief detail spacing than a shoe that is driven by aesthetics, while still maintaining a threshold level of compliance and shock attenuation at heel strike. 
     Once a force is applied to the heel member  14 , as will occur when the shoe is being worn and the wearer is walking, the heel of the shoe will contact the ground. The compliant heel plug  28  will flex or otherwise partly compress under such a force. Compliance is provided by the relief detail spacing. As the force is applied, the relief detail spacing decreases due to the complaint heel plug  16  flexing. Thus, at least a portion of the ground reaction force is absorbed and the wearer is provided with a degree of cushioning. This can be seen in the example of  FIG. 7B , where the relief detail spacing on the anterior side (RD H3 ) is smaller than the relief detail spacing on the anterior side as shown in  FIG. 7A  (RD H1 ). Similarly, the posterior side relief detail spacing (RD H4 ) in  FIG. 7B  is smaller than the posterior side relief detail spacing as shown in  FIG. 7A  (RD H2 ). It should be understood that the medial and lateral relief detail spacing will also be smaller in the case when the heel member is under force than when a force is not applied. 
     In one example, where the posterior relief detail spacing (RD H2 ) is on the order of 5 mm at its maximum value without force applied in  FIG. 7A , the relief detail spacing (RD H4 ) as shown in  FIG. 7B  may decrease between about 1-2 mm (or 20-40%) to 4-5 mm (or 80-100%) due to force applied. Testing has shown compression on the order of about 1 mm with 50 pounds of force, 3 about mm with 150 pounds of force, and substantially full compression at 200 pounds of force. 
     The amount of relief detail compression will vary due to the wearer&#39;s weight as well as the particular motion of her gait and the material(s) used in the compliant heel plug  28 . For example, a greater weight being applied to the shoe may result in higher ranges of compression, while smaller weights may result in smaller ranges of compression for a given embodiment of the invention. Similarly, gaits that produce harder or faster striking of the compliant heel plug  28  against the ground may result in higher ranges of compression, while walking gaits that produce softer or slower striking of the compliant heel plug  28  against the ground may result in lower ranges of compression. The hardness of the walking surface itself may also affect the compression of the relief detail spacing. 
     Furthermore, depending on the point(s) of impact, the force applied to the base section  30  of the compliant heel plug  28  may not be evenly displaced.  FIG. 8  illustrates posterior section  30   a  of the compliant heel plug  28  coming into initial contact with the ground during exemplary motion as the wearer is walking in the shoe. In one example, the posterior section  30   a  has a radius R p  on the order of 10 mm. In other examples, the radius R p  may be between 5-15 mm or at least 3 mm. In some alternatives, the radius R p  may be chosen based on aesthetics. In one scenario, the maximum radius R p  ranges from 5-40 mm. 
     Benefits of radius R p  may be found during heel strike, allowing a more gradual heel strike as compared to a traditional high heel with a straight geometry at the posterior of the heel. The radius R p  provides for a rolling action and increased surface area contact between the base section  30  of the compliant heel plug  28  and the ground, helping to distribute the contact forces and keeping those forces from transmitting up through the heel of the shoe and into the wearer&#39;s body. The radius R p  also increases stability and traction due to enhanced ground contact. In one scenario, the medial and lateral portions of the posterior section  30   a  may also be rounded in combination with the radius R p , although it is not required. 
     As also shown in  FIG. 8 , anterior region  30   b  of the base section  30  of compliant heel plug  28  may also be rounded, having a radius R a . In one example, the radius R a  may be on the order of 3 mm. In other examples, the radius R a  may be between 1-5 mm, or no greater than 7 mm. As above, there is no requirement for the anterior region to have any radius R a . While not shown in the side view of  FIG. 8 , any or all of the posterior region  30   a , anterior region  30   b  and central region  30   c  may include a tread pattern for enhancing contact with the ground. 
     As indicated above, it can be seen in  FIG. 8  that the posterior region  30   a  typically contacts the ground before the anterior region  30   b . The impact forces are thus initially applied primarily to the posterior region  30   a . Thus, in one scenario, the compression of posterior relief detail spacing RD H4  may be greater than the anterior relief detail spacing RD H3 . 
       FIGS. 9A and 9B  illustrate exemplary compression of relief detail spacing as a person is walking. For instance, as shown in  FIG. 9A , the posterior region  30   a  (see  FIG. 8 ) contacts the ground first, thereby causing compression of the relief detail spacing in that region. Then, as shown in  FIG. 9B , as the forefoot section of the article of footwear comes into contract with the ground, the anterior region  30   b  (see  FIG. 8 ) also contacts the ground, resulting in compression of the anterior relief detail spacing as well. Due to gait, weight and other factors, the compression may or may not be uniform around the heel member  14 . 
     According to a further aspect of the invention, the relief detail RD may be positioned as close to the ground as possible. By locating the relief detail RD in this manner, there is a minimal effect on the shoe&#39;s aesthetics as compared to a traditional high-heeled shoe. Further, when walking, the initial application of force is normally introduced at the distal end of the heel. Attenuating this force at the point of contact reduces the length of the moment arm. Applying forces to a mechanism higher up the heel would lengthen the moment arm and magnify the force applied to the heel member. The increased lever action would induce more torque on the heel causing the heel to become unstable under the foot. The increased moment arm would act on the heel member-to-sole connection and is the reason that heel members are secured so tightly to the sole with the added requirement of a very stiff heel member made, e.g., from wood or plastic. 
     In one example, the relief detail RD H1  ( FIG. 7A ) may be positioned on the order of 4-6 mm from the ground contacting base of the anterior region  30   b . In other examples, the relief detail RD H1  may be at least 2 mm or no more than 10 mm from the ground contacting base of the anterior region  30   b . In contrast, the relief detail RD H2  may be positioned on the order of 10-20 mm from the ground contacting base of the posterior region  30   a . In other examples, the relief detail RD H2  may be at least 7 mm or no more than 30 mm from the ground contacting base of the anterior region  30   b . As shown in  FIG. 7A , the position of the relief detail relative to the ground contacting surface may gradually increase from the anterior region  30   b  to the posterior region  30   a.    
       FIGS. 10A-E  illustrate different views of an exemplary embodiment of the suspension heel in accordance with aspects of the invention.  FIGS. 11A-E  illustrate different views of an alternative exemplary embodiment of the suspension heel in accordance with aspects of the invention. Broken lines in  FIGS. 10A-E  and  11 A-E indicate an upper portion of the suspension heel that is affixable to the sole of a shoe. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.