This invention relates to an interchangeable sole system for an item of footwear (e.g., shoes, boots, sandals, slippers) including a sole that can be quickly and easily replaced with other soles having different types of traction surfaces. In particular, the system includes a removable sole unit that interacts directly with a midsole of the footwear. The midsole includes receptacles adapted to help secure the sole unit to the midsole. The interchangeable sole system allows customization of an item of footwear with respect to traction, cushioning, support, fit, performance and/or aesthetic appearance.
Shoes having replaceable soles are well known and are used in many different applications. Examples of shoes where it is desired to have multiple different traction surfaces available on a single shoe are described in U.S. Pat. Nos. 6,813,847, 7,331,123, 7,520,069, and 7,984,569, the contents of which are hereby incorporated by reference in their entireties. These shoes typically include a cavity in the sole of the boot and have a sole plate fill this cavity. The cavity is typically formed in an outsole frame that attaches to a midsole. These soles also have complementary pairs of engageable elements, associated with the sole and sole plate, to provide an interference fit that helps secure the sole plate to the sole. These shoes, however, have a distinct outsole frame that guides and holds the sole plate and that is attached to the midsole.
An example of a removable sole member for a sandal is described in U.S. Pat. No. 6,442,869. The removable soles are attached to the underside of the upper sole by fasteners, screws, snaps, etc. Another example of interchangeable sole system is described in US 2003/0200675. This system includes a series of core modules, a top foot attaching member, and a bottom sole member. The top and foot members have mating components to interconnect with the core modules.
Shoes with interchangeable sole systems are typically heavier than a conventional shoe and have a bulky look. Accordingly, there is a need for a lighter and aesthetically pleasing sole system with improved performance in a variety of footwear applications.
The inventive subject matter overcomes problems in the prior art by providing midsoles for an item of footwear, interchangeable sole systems incorporating such midsoles, and related methods for making such midsoles and sole systems that have one or more of the following features alone or in combinations:
In one possible embodiment, an interchangeable sole system for an item of footwear has a removable sole unit including an engageable element, a midsole, and a receptacle incorporated in the midsole. A portion of the receptacle may be configured to complement the engageable element of the sole unit so that a bidirectional stop is provided that helps secure the sole unit to the midsole. A material property of the receptacle differs from a material property of the midsole so that the midsole provides cushioning to the item of footwear, and the receptacle allows for engagement and disengagement of the engageable element of the sole unit to the midsole without the need for an outsole frame. In the foregoing embodiment, the midsole may include a first material and the receptacle may include a second material, and wherein the second material is less resilient than the first material. In some embodiments, the midsole may include a material having a first durometer and the receptacle includes a material having a second durometer, and wherein the first durometer is less than the second durometer. For example, the first durometer may range between about 55 Asker C and about 65 Asker C. The second durometer may range between about 75 Shore A and about 85 Shore A. In some embodiments, the midsole may include a foamed material, such as EVA or polyurethane, and the receptacle may include an elastomeric material, such as natural or synthetic rubber. In the foregoing embodiment, the receptacle may include a portion that is exposed along a bottom surface of the midsole. In the foregoing embodiment, the receptacle may have a portion defining a recess that complements the engageable element of the sole unit. For example, the portion defining the recess may allow the engageable element from the sole unit to protrude through the receptacle into a portion of the midsole so that the engageable element is held in place and helps secure the sole unit to the midsole. In the foregoing embodiment, the receptacle may include a strip of material disposed along the lateral periphery and along the medial periphery of the midsole, or a spine disposed along a midline of the midsole and one or more fingers extending from the spine to a periphery of the midsole. In some possible embodiments, a first receptacle is located along a medial periphery of the footwear and a second receptacle is located along a lateral periphery of the footwear. In other embodiments, the receptacle may be located in a rearfoot section, a midfoot section, or a forefoot section of the item of footwear. In some embodiments, the midsole may include at least one surface portion with a plurality of rows of teeth running generally perpendicular to the longitudinal axis of the midsole and the surface portion is adapted to engage a set of complementary teeth on the sole unit.
In another possible embodiment, a midsole for an item of footwear provided with an interchangeable sole system may include a receptacle incorporated in the midsole. The receptacle may have a portion exposed along a bottom surface of the midsole. The receptacle may be configured to complement an engageable element associated with a sole unit so that a bidirectional stop is provided that helps secure the sole unit to the midsole. The receptacle may allow engagement and disengagement of the sole unit to the midsole. In the foregoing embodiment, a material property of the receptacle may differ from a material property of the midsole so that the midsole provides cushioning to the footwear and the receptacle allows for engagement and disengagement of the engageable element of the sole unit to the midsole without the need for an outsole frame. In the foregoing embodiment, the midsole may include a material having a first durometer and the receptacle comprises a material having a second durometer, and wherein the first durometer is less than the second durometer.
The inventive subject matter further contemplates methods for making interchangeable footwear systems and midsoles, for example by forming a midsole, and incorporating a receptacle into the midsole, the receptacle may include an engageable portion that is adapted to complement an engageable element of a sole unit for the item of footwear so that engagement of the engageable element to the engageable portion of the receptacle provides a bidirectional stop that helps secure the sole unit to the midsole without the need for an outsole frame. In some embodiments, the receptacle may be incorporated into the midsole by co-molding. In other embodiments, the receptacle may be stock-fitted to the midsole after molding the receptacle area. In yet another embodiment, the receptacle may include an elastomeric material and the receptacle may be incorporated into the midsole by cementing.
These and other embodiments are described in more detail in the following detailed descriptions and the figures.
The foregoing is not intended to be an exhaustive list of embodiments and features of the inventive subject matter. Persons skilled in the art are capable of appreciating other embodiments and features from the following detailed description in conjunction with the drawings.
The following figures show embodiments according to the inventive subject matter, unless noted as showing prior art.
Representative embodiments according to the inventive subject matter are shown in
The inventive subject matter relates to an interchangeable sole unit for an item of footwear including a removable sole unit that is received directly to a midsole of the item of footwear, without the need for an outsole frame. The combination of a sole unit and midsole provides foot supporting and ground engaging functions, as well as other functionality, that sole systems are known to provide, such as cushioning, support, fit, performance and/or aesthetic functions. To secure the sole unit to the midsole, the bottom surface of the midsole exposes receptacle areas or receptacle zones that are adapted to receive engageable elements protruding from the sole unit. The receptacles are incorporated in the midsole and may be made of a material that is less resilient than the surrounding midsole material. The system allows combining the functions of providing support and cushioning to the footwear in a single layer. This system also creates a lighter shoe because no outsole frame is needed and less material is needed to create a shoe sole. For example, heavier receptacle zones may be interspersed in a lighter midsole material. Additionally, the mounting of the sole unit directly into the midsole allows for a flush mounting of the sole unit to the midsole thereby creating an item of footwear with an overall thinner sole and enhanced aesthetic of the shoe, i.e., sleeker look along the side of the shoe. Also, the sole unit attaches to the midsole without exposure of engageable elements, for example along the sides, of the item of footwear. The engageable elements are locked into the midsole by arranging the sole unit onto the midsole so that by walking or pushing the sole unit against the midsole, the engageable elements will lock into the receptacle. The wearer can hear and feel the engageable elements click into place in the receptacles of the midsole.
As used herein, “footwear” refers to any item for supporting the foot and engaging the ground and encompasses shoes, sandals, boots, slippers, overshoes, athletic shoes, and other footwear articles. “Receptacle area,” “receptacle zone,” and “receptacle” refers to a structure or arrangement that is incorporated in a midsole and that has at least one material property that is different from a material property of the surrounding midsole. “Incorporated” refers to the receptacle being securely formed or fixed in the surrounding midsole material, for example by molding, bonding, or other suitable techniques. The specific material properties and structure of the receptacles provide an engagement/disengagement system. The receptacles may have material properties that allow the structure to return or tend to return to a prior or original position so that it contributes to the lodging of an engageable element in the midsole. The differences in material properties may be, for example, differences in resilience, hardness, flexibility, and/or weight of the materials. For example, materials such as EVA (Ethylene vinyl acetate) or polyethylene foam may be made in different grades of material having different resiliency, hardness, density, or other differences in physical properties.
The midsole is usually a layer of material between a layer on which the foot rests, such as an insole or sock liner, and a ground-contacting sole. Typically, the midsole provides cushioning to the footwear, for example as a uniform layer of a foamed EVA material. The EVA material is generally soft and resilient and does not provide for a reliable and secure engagement of the engageable elements of the sole unit.
In contrast, a midsole, as used by the inventive subject matter, includes a single layer having a distinct zone or multiple distinct zones with material properties that are different from the material properties of the surrounding midsole material. The midsole is adapted to provide a secure engagement for the sole unit as well as to provide support to the footwear, without the need for an outsole frame, in combination with cushioning functions of the conventional midsole layer. In some embodiments, the midsole may connect to a shoe upper for enclosing or securing the shoe around a foot. The upper could be a complete enclosure that surrounds a foot or it could be a partial enclosure such as a set of sandal straps.
In some embodiments, the sole unit and midsole may be coupled to each other by various configurations of male-female interconnections and/or interference-fit arrangements. Such elements may be referred to as “engageable elements.” Generally, the various pairs of engageable elements may be distributed across a sole assembly in any manner or number provided that they reasonably securely engage the sole unit for purposes of an intended use of an item of footwear. For example, all male parts could be disposed on the sole unit and all female parts could be disposed on the midsole as receptacles, or vice versa. For example, receptacles may include male elements that protrude from a midsole bottom surface to engage complementary female elements on the sole unit. In some embodiments, the sole unit or the midsole could each have a set of male-female parts that engage corresponding parts on the other of the sole unit or midsole. In some embodiments, the engageable elements may include snap fit fasteners, hooks, etc.
As used herein, “to complement” or “complementary” means geometrically shaped and sized for snug interconnection, or a male or female part that is not so shaped and sized but has material properties such that it will conform to a male or female part to which it is being interconnected.
The engageable elements of the sole unit provide a bidirectional stop that helps prevent the movement of a surface of the sole unit relative to the midsole. As used herein, a “bidirectional stop” generally means stop that limits movement along at least one axis from either direction on the axis. For example, a bidirectional stop may be a set of elements that are disposed on portions of a sole unit and midsole that are intermediate the end portions of the sole unit and midsole and that engage each other so that forward and rearward travel of the sole unit relative to the midsole is limited. The bidirectional stops may also limit relative movement of each sideways.
In the embodiments shown, the sole unit and midsole are coupled by engageable elements that protrude from the sole unit and that interact with a complementary structure in a portion of the receptacle, such as a recess, cavity, passage, or other complementary engageable element that holds or guides the engageable element to provide a bidirectional stop. The material properties of the receptacle allow the receptacle to provide a secure grip that holds the engageable elements in place once engaged and the sole unit is in use. The engagement is sufficient to resist forces on the sole unit that arise during ordinary use of the shoe. However, the sole unit may be removed when additional forces are applied to the sole unit, for example by pulling a strap at the rear of the sole unit downward to remove the sole unit. In some embodiments, one or more receptacles are incorporated in the midsole and exposed along a bottom surface of the midsole. In other possible embodiments, the receptacle may be cradled by or embedded in the midsole material.
The sole assembly includes a forefoot section, midfoot section, and rearfoot (or heel) section. The sole assembly further includes a lateral half and a medial half.
In some embodiments, pods may have transition areas between the pod material and the midsole material. For example, as shown in
The interchangeable sole system includes a sole unit that is generally sized to fit with and complement the midsole. The midsole may or may have not a peripheral border to contour the sole unit. In some possible embodiments, there may be a partial peripheral border. In other embodiments, the footwear may include a single sole unit or a plurality of sole units that are separated with different properties, e.g., varying traction or durometer, and the use of a specific sole unit may be depend on the activity. Use of separate sole units allows for a user to customize the sole properties, e.g., to compensate for pronation or to provide more or less traction in different areas of the foot, for example, in forefoot, midfoot and/or rearfoot locations. In other embodiments, sole units may be positioned at lateral and/or medial sides of the footwear.
In some embodiments, the sole unit may have a uniform thickness. In other embodiments, the thickness of the sole unit may vary, for example, the sole unit may have a heel portion that is raised to provide a boot heel or a central portion might be recessed to provide cushioning. The same effect may be accomplished by variations in the thickness of the midsole.
The midsole may be made of a generally compressible material, such as a shape retentive, flexible polymer or foamed material. In some embodiments, the midsole material may have a hardness with a durometer ranging between about 55 Asker C and about 65 Asker C, for example, a hardness of about 60 Asker C. The receptacle may include a material with a hardness ranging between about 75 and about 85 Shore A durometer, for example, a hardness of about 80 Shore A durometer. These numbers are intended to be example durometers, and durometers of varying degree may be appropriate, depending on the specific application to be pursued. Examples of suitable materials include rubbers, foams, elastomers, visco-elastomers, plastics, natural and synthetic leathers, textiles, fibers and metals. Some of these materials may come in different densities making them suitable both as midsole material and as receptacle material. In some embodiments, a combination of materials may be used. In other possible embodiments, a midsole may have receptacles that are formed by a gradual change in material properties, for example, material properties may transition gradually between the midsole and receptacle area(s).
In some embodiments, a firm midsole material may include areas that provide for engageable elements that are complementary to engageable elements on a sole unit.
Optionally, a sole unit or midsole may include cushioning elements. “Cushioning materials” and “cushioning elements” refer to basic shock absorbing, energy return, and/or protective underfoot materials or structures that are intended to react to the forces of foot strike by providing force attenuation, dissipation, dampening, or energy return (spring), which are typically included on sports and athletic shoes. For example, a cushioning element may include a consistent and uniform layer of shock absorbing and protective material, such as EVA or polyurethane, placed in a shoe between the foot and the ground, or customized placements of varying cushioning materials and structures under a foot, or may be based on EVA or polyurethane foam, visco-elastomers of foam or gels, fluid filled bladders, mechanical springs or resiliently collapsible mechanical structures, fluid (e.g., air) springs, or any combination of the foregoing.
The flexibility of the midsole and/or sole unit may vary according to the demands of a particular user or intended use. For example, the midsole or sole unit may be provided with more support on a medial side to help a runner whose foot pronates. Likewise the midsole or sole unit may be provided with more support on a lateral side to compensate for a runner whose foot supinates. Additionally, a midsole or sole unit may be constructed with a material that provides resistance to environmental conditions such as sharp objects or corrosive chemicals for safety in work places where such conditions may be present.
In some embodiments, midsoles may also have flexural lines corresponding to the lines of flex in a foot. The flexural lines may provide a balance between stiffness and flexibility. In some embodiments, flexural lines may be formed by the removal of midsole material or by ridges of deposit of midsole material. In other embodiments, longitudinal ribs may be provided including a different kind of material. For example, some sole units may have longitudinal protrusions or ridges that are complemented by corresponding indentations in the midsole or receptacle zones. In some embodiments, for example for wading boots, the midsole and/or sole unit may include channels, ridges or drain ports that channel water away from the shoe and thereby prevent water absorption by the shoe, enhance drying of the shoe, reduce overall weight of the shoe and lead to more comfort and less fatigue for the wearer.
In another possible embodiment, the midsole may include a cupsole or otherwise be part of a cupsole construction. A cupsole construction refers to a molded, contoured sole with vertically upward extending sidewalls along the perimeter of the shoe. The sidewalls are usually stitched to the outside of the shoe upper. For example,
Located in the midsole at the toe end may be a slot adapted to accommodate a tab at the toe end of the sole unit. The tab fits into the slot of the midsole when the sole unit is inserted into the cavity. The slot may be made of midsole material, receptacle material, or any other suitable material. The slot may be a thin slot integrated into the midsole or may be formed as a distinct piece attached to the midsole.
In some embodiments, a ledge may extend from the midsole below the slot. For example,
In some possible embodiments, a toe cap may be provided to the midsole as a distinct structure, while in other possible embodiments it may be integrated as part of the midsole. For example in the embodiment shown in
In another possible embodiment, a midsole may include receptacles in the form of a strip covering an area associated with engageable elements of the sole unit. An example of such a design is shown in
In another possible embodiment, receptacles in a midsole may take the form of a web-like structure. For example, as shown in
Another example of another possible lay-out for receptacles in a midsole is shown in
The inventive subject matter further contemplates a method of making an interchangeable sole system for an item of footwear by providing a midsole comprising a first material with a receptacle of a second material, and providing a sole unit having at least two engageable elements spaced along a peripheral portion of the sole plate, the receptacle adapted to engage the engageable element associated with the sole unit, and wherein the second material is less compressible than the first material so that the first material provides cushioning to the footwear while the second material allows for engagement and disengagement of the engageable elements of the sole unit to the midsole without the need for an outsole frame.
Contemplated fabrication methods for a midsole with receptacles may include molding, injection molding, direct-injection molding, one-time molding, composite molding, insert molding, co-molding separate materials, or other techniques known in the art, alone or in combination. Dampening elements may also be incorporated into the sole unit and/or midsole disclosed herein, for example, dampening elements that allow reducing the amplitude of oscillations, vibrations, or waves. Other possible embodiments may use a unitary midsole construction. For example, the entire periphery could be formed of a material that is less resilient than the rest of the midsole. In other possible embodiments, a midsole may have single or plural co-molded layers of material to form receptacles. In other possible embodiments, the midsole may have a laminated structure.
In one example embodiment, the midsole may be made based on a traditional midsole that is provided with recesses for forming the receptacle and a receptacle is stock fitted, for example glued to an EVA midsole. In other possible embodiments, a frame of receptacle can be made of a rubber material that is cemented into recesses in the midsole. Alternatively, the frame could be co-molded with the midsole. Examples of midsole materials may include EVA, polyurethane, neoprene, etc. Examples of receptacle materials may include thermoplastic polyurethanes, natural rubber, synthetic rubber, or combinations thereof. In other embodiments, the sole system may include a firmer midsole material that accomplishes both functions of cushioning and engagement/disengagement capacities.
In some embodiments, receptacle may be inserted into the midsole and embedded by methods that include adhesives, bonding agents, welding, mechanical bonding, interlocking shapes or other mechanical or chemical fastening means know to persons in the art, alone or in combination.
The footwear may be made by cementing, stitching, or other common bonding methods.
To facilitate the releasability or attachability of the sole unit to the midsole, one or more hand tools may be provided with or in the sole system. The hand tool generally is a structure or structures that are disposed on the footwear and can be pulled, pushed, turned or otherwise manipulated to cause the sole unit and sole unit receiver to engage or disengage. The hand tool may be located any place on the sole unit, but normally it would be placed in a manner that is not subject to wear and tear and does not interfere the performance or comfort of a shoe. Accordingly, it may be placed on a side, heel or front of a shoe, and it interfaces where a sole unit and sole unit receiver join together. It may also be recessed in the bottom of a sole assembly.
Footwear according to the inventive subject matter may come in many different styles. The durometer of the material, the number and shape of the engageable elements and corresponding receptacles and their location may vary, as well as the structure of the footwear.
Persons skilled in the art will recognize that many modifications and variations are possible in the details, materials, and arrangements of the parts and actions which have been described and illustrated in order to explain the nature of the inventive subject matter, and that such modifications and variations do not depart from the spirit and scope of the teachings and claims contained therein.
All patent and non-patent literature cited herein is hereby incorporated by references in its entirety for all purposes.
This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/450,391, filed Mar. 8, 2011, the content of which is hereby incorporated by reference as if recited in full herein for all purposes.
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