Patent Publication Number: US-2004045190-A1

Title: Footwear traction assist

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to a traction attachment for footwear, especially a traction attachment for use under wintry or arctic conditions on icy or snow covered terrain.  
       BACKGROUND AND SUMMARY OF THE INVENTION  
       [0002] The invention concerns a traction device that can be readily installed on a person&#39;s boot or shoe to provide improved traction on snowy or icy terrain. The device can be likened to snow tires for the feet. An important object of the invention is to provide a traction attachment that is rugged and stable on the person&#39;s boot, but is at the same time very light in weight. Typically, the attachment weighs only about six ounces, such that it offers no measurable hindrance to each foot movement.  
       [0003] A typical prior art traction attachment is shown in U.S. Pat. No. 5,813,143, issued on Sep. 29, 1998 in the name of Michael Bell. That patent shows an integral one piece unit molded out of resilient material, e.g. rubber or polyvinyl chloride, and adapted to fit onto a person&#39;s footwear (boot or shoe) to provide improved traction for the person.  
       [0004] The molded unit includes a sole, toe encirclement at the front end of the sole, and a heel encirclement at the rear end of the sole. The heel encirclement includes side straps that are stretchable, so that the molded unit can fit more than one size boot or shoe. The shank area (or arch area) of the sole has a large rectangular opening, apparently for reducing the resistance of the molded unit to longitudinal stretching (while the unit is being placed on the footwear). Several spikes, or cleats, are secured to the bottom surface of the molded sole, to provide an improved traction on snow or ice.  
       [0005] The present invention relates to a footwear traction attachment that includes a flexible molded panel adapted to fit against the footwear sole, an integral front strap means for fitting around the toe of the footwear, and an integral rear strap means for fitting around the heel of the footwear. The flexible panel includes a shank area that is of reduced thickness and width (compared to the heel and toe areas), such that the shank area is stretchable longitudinally to vary the spacing between the toe and heel areas of the panel. The panel construction enables the traction attachment to be readily stretched, so as to fit a range of different footwear sizes. Typically, four half sizes can be accommodated with a single traction attachment size.  
       [0006] The front strap means and the rear strap means are formed of a stretchable (elastomeric) material, so as to be stretchable independently of the aforementioned panel. Therefore, the strap means can fit snugly on differently shaped footwear toes or heels, without regard to stretch or non-stretch of the flexible panel.  
       [0007] The traction attachment includes multiple metal cleats replaceably secured to the flexible panel in the frontal area and heel area of the panel (but not in the shank area). Each cleat has a threaded post section that threads into a threaded socket embedded in a raised (or protruding) island integrally formed on the panel.  
       [0008] Each metal cleat can include an annular hollow cup-shaped traction configuration having a sharpened annular edge designed to bite deeply into ice or snow. Each metal cleat can be replaced should it become worn or damaged.  
       [0009] In preferred practice of the invention, the flexible panel (covering the sole of the footwear) is formed of two separate layers of elastomeric material, i.e. an upper layer is preferably a low durometer material, e.g. an elatomer having a durometer of approximately thirty-seven. The lower layer is a high durometer material, e.g. an elastomer having a durometer of about 70. The upper layer material is selected primarily for its ability to stretch (for achieving a snug fit on a range of different footwear sizes and shapes). The lower layer material is selected primarily for durability and abrasion resistance.  
       [0010] Upper and lower panel layers are bonded together along their facing surfaces. Additionally, mechanical interlocking connections are employed between the two elastomeric layers, to provide a laminated panel resistant to delamination forces. In one preferred arrangement, the lower panel is molded to have multiple protuberances designed to fit into mating openings in the upper layer, whereby the two layers are mechanically locked together so as to resist shear forces that might tend to produce delamination of the two layers.  
       [0011] The protuberances on the lower layer are vertically aligned with the raised islands that anchor the aforementioned cleats. Therefore, the cleat anchorages are reinforced against terrain forces that might tend to disturb or tear the cleats from the laminated panel. The cleats have improved resistance against wobbling or shifting relative to the panel while the person&#39;s foot is exerting a traction force on ice or frozen terrain.  
       [0012] The number of cleats employed on the traction attachment can vary. In a preferred embodiment of the invention nine cleats are employed. Five cleats are mounted on the frontal area of the flexible panel, and four cleats are mounted on the heel area of the panel. In order to minimize build up of ice or snow between the traction attachment panel and the sole of the footwear, the panel is molded to include drainage notches or grooves at spaced points along the panel edge. As the person&#39;s foot applies downward pressure on the traction attachment panel, any snow or ice accumulations in the interface between shoe sole and attachment tend to be squeezed into the drainage grooves and out onto the terrain. The drainage grooves allow any ice, snow or water to drain out of the interface between the footwear sole and traction attachment, thus reducing the overall loading on the person&#39;s foot.  
       [0013] As stated earlier, an important object of the invention is to provide a traction attachment that is rugged and stable on the person&#39;s foot, but is at the same time very light in weight. In one particular embodiment of the invention, the traction attachment weighs about six ounces. The low weight is attributable, at least in part, to the fact that the traction panel is a laminated two layer construction in which the upper layer is a low durometer elastomer that is stretchable to conform to the footwear, while the lower layer is a high durometer elastomer that is tough and resistant to abrasion forces. By using two different elastomers it is possible to optimize the wall thickness of each layer for its intended function, while at the same time holding the overall weight within reasonable limits.  
       [0014] Specific features and advantages of the invention will be apparent from the attached drawings and description of an illustrative embodiment of the invention. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015]FIG. 1 is a side elevational view of a traction attachment constructed according to the invention. The footwear, on which the attachment is installed, is shown in dashed lines.  
     [0016]FIG. 2 is a top plan view of the traction attachment depicted in FIG. 1.  
     [0017]FIG. 3 is a sectional view taken on line  3 - 3  in FIG. 2.  
     [0018]FIG. 4 is a bottom plan view of FIG. 3 construction.  
     [0019]FIG. 5 is an enlarged cross sectional view taken on line  5 - 5  in FIG. 4.  
     [0020]FIG. 6 is a fragmentary view taken in the direction of arrow  6  in FIG. 5.  
     [0021]FIG. 7 is a bottom plan view of an elastomeric panel component employed in  
     [0022]FIG. 8 is a top plan view of two other panel components used in combination with the FIG. 6 component, to produce a multi-layer panel, according to the invention.  
     [0023]FIG. 9 is a view taken in the same direction as FIG. 3, but showing another form that the invention can take. FIG. 3 represents a preferred embodiment of the invention. 
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION  
     [0024] Referring to FIGS. 1 and 2, there is shown a traction attachment  10  constructed according to the invention. The attachment is shown in an installed position on a person&#39;s shoe or boot  12 , shown in dashed lines. The term “footwear” will be used herein as a generic description for a person&#39;s boot or shoe of a type that is worn by a person when walking, climbing or hiking on snow or icy terrain. The traction attachment  10  is designed to provide increased traction on snow or icy surfaces, as well as dirt or gravel.  
     [0025] The traction attachment includes a flexible panel  14  adapted to fit flatwise against the sole of footwear  12 , a front strap means  16  carried by the panel for fitting around the toe of the footwear, and a rear strap means  18  carried by the panel for fitting around the heel of the footware. Each strap means  16  or  18  is formed of a low durometer elastomer, so that the strap means can stretch to a limited extent for snugly fitting differently sized or differently shaped toes and heels of footwear.  
     [0026] Flexible panel  14  carries nine downwardly projecting steel cleats  44  that provide traction in ice, snow, dirt, gravel, etc. FIG. 4 is a bottom view of panel  14 , showing the cleat  44  pattern. Five cleats are mounted on the frontal section  31  of the panel. Four cleats  44  are mounted on heel section  32  of the panel. Shank area  33  of the panel is devoid of cleats.  
     [0027]FIG. 5 shows a mechanism for anchoring each metal cleat  44  to panel  14 . Each cleat includes a threaded post that threads into a metal socket  42 , embedded or encapsulated, within a thickened section of panel  14 , whereby the socket is precluded from tearing away from the panel. Each metal cleat can be replaced should it become worn or damaged.  
     [0028] As indicated earlier, the flexible panel  14  is secured to the footwear (boot or shoe)  12  by a front strap means  16  and a rear strap means  18 .  
     [0029] Strap means  16  is a low durometer elastomer that includes a front central strap element  19  located on the longitudinal axis  20  of the footware attachment, and two side strap elements  21  and  22  connected to each side edge of panel  14 . The strap elements merge together to form a central bridge  24  that is adapted to overlie the upper surface of the toe on footware  12 . The strap elements are elastic so as to fit snugly on a range of different footwear toe sizes and styles.  
     [0030] Strap means  18  includes a cross piece  26  adapted to fit against a rear central surface of the footware heel, and two strap elements  27  and  28  extending downwardly and forwardly from each end of the cross piece to connect with edge areas of panel  14 . The cross piece and associated strap elements  27  and  28  are formed of a low durometer elastomer, such that the cross piece can stretch to a limited extent for conforming to differently dimensioned footwear heel surfaces. Plural ridges  29  (FIG. 3) are formed on the front surface of cross piece  26 , to ensure an improved grip of the cross piece on the footwear heel surface.  
     [0031] The cross sectional dimensions of the cross piece and strap elements are selected, in conjunction with the durometer of the elastomer, to achieve a desired elasticity of the front strap means  16  and rear strap means  18 , whereby the strap mechanisms are enabled to snugly fit a range of different footwear toe and heel styles and sizes. The durometer of the elastomer used for strap means  16  and  18  is preferably about thirty-seven.  
     [0032] Panel  14 , is a dual density multi-layer laminated construction formed out of two different elastomers. FIGS. 7 and 8 show the panel components in plan view. The upper layer (or lamination)  30  is show in FIG. 7; it includes a frontal section  31 , heel section  32  and shank  33  connecting the frontal and heel sections. The upper layer is formed of a relatively soft elastomer having a durometer of about thirty-seven. The vertical thickness of layer  30  is preferably about 0.16 inch. Nine toothed openings  34  are formed in layer  30  to mate with similarly shaped protuberances  36  formed on two lower layers  38  and  40  (when the lower layers are bonded to the upper layer).  
     [0033] Lower layer  38  has a shape that conforms to the shape of frontal section  31  of the upper layer, so that when layer  38  is bonded to the undersurface of layer section  31 , protuberances  36  fit snugly into the mating openings  34  to form a mechanical interlock between layers  30  and  38 .  
     [0034] Lower layer  40  has a shape that conforms to the shape of heel section  32  of layer  30 . Four protuberances  36  on the upper surface of lower layer  40  fit into the aligned toothed openings  34  on heel section  32  to form a mechanical interlock between layers  30  and  40  (when layer  40  is bonded to layer  30 ).  
     [0035] Protuberances  36  are vertically aligned with certain internally threaded metal sockets  42  that serve as anchorages for hardened steel cleats  44  (FIG. 5), such that protuberances  36  transfer a fraction of the traction force from the cleats to upper layer  30  of panel  14 , while at the same time reinforcing the elastomeric material in contact with sockets  42 . Protuberances  36  absorb shear loadings on the interfaces between layers  38  and  40 , and upper layer  30 , thereby protecting the laminated panel from delamination forces that occur when the person exerts a pushing or pulling force on icy terrain.  
     [0036] Lower layers  38  and  40  are formed of an elastomer having a relatively high durometer, e.g. an elastomer having a durometer of about seventy. The layer material is selected primarily for toughness and abrasion resistance. The aim is to preclude the metal cleats  44  from exerting oblique forces on the elastomeric material in contact with sockets  42 , which could eventually tear the sockets out of the elastomer. The nominal thickness of each layer  38  or  40  is only about 0.16 inch. However, protuberances  36  effectively increase the layer thickness in those areas that are used to mount the cleat sockets.  
     [0037] By comparing FIGS. 7 and 8, it will be seen that the laminated panel  14  is relatively thick in the frontal section of the panel and in the heel section of the panel. The shank area  33  of the panel is formed solely by upper layer  30 , such that the shank area is relatively thin in the vertical (thickness ) direction.  
     [0038] Shank area  33  has a cross sectional dimension that enables the shank area of the laminated panel to stretch longitudinally, while the frontal section and heel section of the panel are substantially non-stretchable. In this regard, the high durometer layers  38  and  40  tend to add stretch resistance to the panel, while the low durometer shank area  33  has the desired elasticity needed for localized longitudinal stretching of the panel, e.g. for stretching the panel to fit a range of different footwear sizes. Panel  14 , is a dual density panel, that is adapted to have a tension fit binding on a range of different size footwear.  
     [0039] In FIG. 5 the longitudinal axis of panel  14  is referenced by numeral  20 . Shank area  33  of the panel has a width dimension  52  (transverse to axis  20 ) that is substantially less than the corresponding width dimension for the frontal section or heel section of the panel. Typically, width dimension  52  will be about thirty-five millimeters. The cross sectional dimension of the shank area  33  (thickness and width) is selected, along with the durometer of panel lamination (layer)  30 , so that the panel stretch action is confined to shank area  33 .  
     [0040] As viewed in FIG. 5, edges  53  of shank area  33  are concave so that the shank width dimension is increased where the shank area connects with the transverse edges  54  and  55  of the panel frontal section and heel section. The increased width dimension strengthens those parts of the shank area most likely to tear or rupture when the panel is subjected to a longitudinal stretching force, i.e. the anchored ends of the shank that cannot relieve the stress in the form of strain.  
     [0041] Although not readily apparent from the drawing the front strap means  16  and rear strap means  18  are integral with upper layer  30  of panel  14 , preferably by molding the panel layer  30  and strap means together in a single step molding operation. The panel layer  30  and both strap means are formed of the same low durometer elastomer so as to have a desired elasticity.  
     [0042] In adapting a given size traction attachment to fit a range of different footwear sizes and shapes, there are two independent stretching actions that can take place. First, panel  14  can be stretched longitudinally in shank area  33  to vary the spacing between the front strap means  16  and rear strap means  18 . Second, the front strap means  16  can be independently stretched to have a snug fit on various different footwear toe sizes and styles. Similarly, the rear strap means  18  can be independently stretched to fit a range of footwear heel configurations. In this regard, cross piece  26  curls around a substantial length of the heel surface so as to be capable of substantial changes in cross piece length.  
     [0043] Referring to FIGS. 4 and 5, it will be seen that the steel cleats  44  are located at spaced points along the peripheral edge of panel  14 , giving the traction attachment a wide stance tractive action for improved footware stability. The central area of panel  14  proximate to the longitudinal centerline  20  is occupied by two sets of chevron type treads  57  and  58  extending downwardly from frontal layer  38  and heel layer  40 . Chevrons  57  have rearwardly facing ve rtical surfaces that stabilize the panel against slippage in the rearward direction, whereas chevrons  58  have forwardly facing vertical surfaces that stabilize the panel against slippage in the forward direction. The chevrons augment the tractive action of cleats  44 .  
     [0044] As stated earlier, each metal cleat  44  is threadably mounted in a metal socket  42  encapsulated within one of the lower layers  38  or  40  of the laminated elastomeric panel. Each metal cleat includes an annular cup-like protrusion that has an annular sharpened edge  60  designed to bite into icy terrain so as to achieve a tractive action. The annular wall of the hollow cup-like protrusion has a screw driver slot  62  therein that facilitates installation or removal of the cleat from the associated socket  42 . All of the cleats are similarly constructed.  
     [0045] Each metal socket  42  is encapsulated within an island  64  protruding from the laminated panel  14 , to provide lateral support for the socket. As shown in FIG. 5, the side surface of the protruding island is stepped to provide some traction in soft terrain. The islands are molded integrally with elastomeric laminations (layers)  38  and  40 .  
     [0046] As previously noted, metal sockets  42  are vertically aligned with protuberances  36  on elastomeric layers  38  and  40 . Therefore, the elastomeric material encircling each socket  42  is reinforced by the associated protuberance  36 . Shear loadings on the metal cleats  44  tend to be resisted by the associated protuberances  36  that are mechanically locked to the upper lamination  30  of the cleat-support panel. Protuberances  36  tend to resist panel delamination forces.  
     [0047] The laminated panel  14  is provided with plural drainage, and is provided with plural drainage grooves  66  interspersed with metal cleats  44  at spaced points along the peripheral edge of the panel. As shown in FIG. 4, there are four V-shaped drainage grooves  66  in the frontal portion of the laminated panel, and two drainage grooves  66  in the heel portion of the panel. Each drainage groove is located between two cleats, so as to be capable of shedding snow or water that might accumulate in the spaces between cleats. The drainage grooves extend through the entire panel thickness, so that water or ice accumulations in the crack interface between the footwear sole and upper surface of panel  14 , can migrate easily into the drainage grooves.  
     [0048] The apex of each V-shaped drainage groove  66  forms a potential weak point that could lead to tearing or rupture of the elastomeric materials. To strengthen the panel against such rupture, each lower layer  38  or  40  has molded reinforcement ribs  68  that provide local reinforcements at the apex of each V-shaped drainage groove, as well as longitudinal rigidification of layers  38  and  40 .  
     [0049] The traction attachment is designed to achieve a combination of useful properties, including localized elasticites enabling a given size attachment to fit a range of different footwear sizes, a good stable support for each metal cleat, drainage for ice of snow accumulations, and a relatively low overall weight.  
     [0050] As shown in FIG. 4, the longitudinal centerline  20  is a straight line, such that the traction attachment is capable of fitting on either a left boot or a right boot. In actual practice the attachment is made in two versions, i.e. for a left shoe or a right shoe; the longitudinal centerline is slightly curved.  
     [0051]FIG. 3 shows a preferred embodiment of the invention. FIG. 9 shows an alternate construction that can be employed. In the FIG. 9 version panel,  14  is a single molded elastomer having a durometer of approximately fifty. The FIG. 9 panel represents a compromise between elasticity and durability.  
     [0052] The drawings show specific forms that the invention can take. However, it will be appreciated that the invention can be practiced in various forms and configurations.