Patent Grant
10004294
The present application is generally related to footwear and in particular soles for slip resistance and improved performance on slippery surfaces.
In many industries, slip and fall accidents represent the highest or second highest type of workers compensation claims. Indeed, slip and fall accidents account for nearly 11 percent of all workers compensation claims as well as 13 percent of all costs related to claims. In some circumstances, it is possible to minimize accidents though rigorous cleaning and inspection protocols, through the inclusion of certain flooring surfaces, or other programs inclined to limit falls, however, the use of proper footwear can also have an impact in limiting falls. Accordingly, slip resistant shoes and soles provide a useful tool for employers and employees to help limit injuries in the workplace.
In the United States, there are no current legal standards for measuring slip resistance of footwear and manufacturers typically use the standards of non-governmental organizations such as the International Organization for Standards (ISO) and the American Society for Testing and Materials (ASTM). Some manufacturers use the Brungaber Mark II (PIAST) slip tester and utilize standards issued by organizations such as the ISO. See ISO 13287-2006 “Personal Protective Equipment-Footwear-Test Method for Slip Resistance, ISO, Geneva, Switzerland.”
Regardless of what standard is used, one type of footwear may test best under certain conditions, but fail under other conditions. For example, shoes and soles designed for use on icy surfaces may not necessarily be as well suited for hard surfaces having liquid spills, or oil, or dust, among other possible materials that increases the chance for slipping. Similarly, the actual tested conditions, including temperature, humidity, and pressure, can all impact results of slip resistance.
In seeking to manufacture a slip resistant sole, it is generally recommended to maximize contact with the walkway surface by pushing or squeezing water and contaminants away from the sole at the heel strike, mid stance and toe-off phases of the gait cycle. See Shoe and Allied Trade Association (SATRA). Wilson, M., Development of SATRA Slip Test and Tread Pattern Design Guidelines, In STP 1103, Slips, Stumbles and Falls: Pedestrian Footwear and Surfaces, B. Everett Gray editor, ASTM International, 100 Barr Harbor Dr. W. Conshohocken, Pa. Maximizing contact with the surface provides for more surface area for friction between the shoe sole and the surface, so as to prevent falls.
Furthermore, the sole or tread material may also impact the slip resistance of the shoe or sole. Shoe manufacturers typically use styrene butadiene rubber (SBR) or nitrile-butadiene rubber (NBR), as well as a number of polyurethane materials for the sole of the footwear. The spectrum of materials includes soft to hard materials. Typically, soft materials offer improved traction but limited durability. Harder materials, while providing for improved durability, typically have reduced traction when compared to softer materials. On icy surfaces, a different material may be appropriate, as rubber alone is often insufficient, and studded soles may be necessary for proper traction and slip resistance. See “Loss Control Reference Note: Preventing Slips and Falls: Slip Resistant Footwear,” Liberty Mutual Group, LC 5407 R2, September 2009.
The prior art has attempted to provide a shoe sole having slip resistant properties, see. e.g.: EP 1762151, WO 2000004802, WO 1999022614, CA 1260704, US D674585, EP 0383489, EP 0367297, US 20130008059, EP 2449906, U.S. Pat. No. 4,724,624, and US 20090188132, yet each of designs have various limitations that preclude their use in one or more situations.
Accordingly, there is a need for an improved shoe comprising slip resistant soles.
In a first embodiment, a shoe comprising a slip resistant sole wherein said sole comprises a plurality of arcuate shaped lugs having non-linear edges and defined by a groove transecting each lug, wherein the arcuate shaped lugs are arranged into a pinwheel pattern group comprising three arcuate shaped lugs, and wherein said pinwheel pattern groups are substantially disposed on the bottom portion of the sole.
In a further embodiment, an aspect of the present disclosure is a shoe comprising a slip resistant sole having a pattern comprising: a plurality of arcuate shaped lugs, each having a narrow end and a bulbous end, wherein said narrow and wide ends are bisected by a predetermined groove, and wherein said plurality of arcuate shaped lugs are organized wherein three arcuate shaped lugs are arranged in a pinwheel pattern group wherein the bulbous ends are centrally proximate, and wherein said plurality of pinwheel pattern groups are disposed of on the bottom of said sole.
In a further embodiment, an aspect of the invention is a slip resistant sole comprising a plurality of pinwheel lug groups, wherein each said pinwheel lug group comprises three pairs of lugs; wherein each pair of lugs having an arcuate shape comprising a narrow lug section and a bulbous lug section having a groove disposed between the two lugs; and wherein said three arcuate shaped lug pairs are arranged such that said bulbous ends are centrally situated in the pinwheel lug group and the narrow ends are radially aligned away from the center creating the pinwheel shape.
The embodiments of the invention and the various features and advantages thereto are more fully explained with references to the non-limiting embodiments and examples that are described and set forth in the following descriptions of those examples. Descriptions of well-known components and techniques may be omitted to avoid obscuring the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those skilled in the art to practice the invention. Accordingly, the examples and embodiments set forth herein should not be construed as limiting the scope of the invention, which is defined by the appended claims.
As used herein, terms such as “a,” “an,” and “the” include singular and plural referents unless the context clearly demands otherwise.
As used herein, the term “about” means within 10% of a stated length.
As used herein, the term “shoe” includes shoes, sandals, boots, clogs, and other items intended to be worn as footwear.
As used herein the term “arcuate lug” or “crescent lug” or “arcuate or crescent shaped member” refers to the arcuate or crescent shaped feature of numerical identifier 2, which is made up of a narrow and bulbous end as identified in
As used herein the term “pinwheel design” refers to the arrangement of the crescent lugs into a propeller like, or pinwheel like arrangement of three crescent lugs and as shown in
As used herein the term “degree of sharpness” refers to the angle between the top and side of a lug. For example,
All references cited herein are incorporated by reference in their entirety.
A primary strategy in designing slip resistant shoes is to maximize contact between the lug and the surface while expelling a material having a low coefficient of friction from the surface. In simple terms, you provide as many points of contact between the shoe and a surface, and expel any of a various number of materials that are on that surface that have a low coefficient of friction. For example, it is widely known that oil reduces friction between two surfaces.
A further aspect of slip resistance relates to the degree of sharpness of the angle (typically ranging from about 0 to about 30 degrees as measured from the vertical) of the lug. An angle of 0 degrees representing that the side of the lug (92,
Surfaces are not always level and flat, and people have different walking mechanics, each of which provides for a variety of contact points between a shoe and a surface. Some people first strike the heel of the foot to the surface while walking or running, others the ball of the foot, and yet others have pronation issues either over pronation or under pronation that impacts the location of the first contact point between the shoe and the surface, as well as the points between the shoe and the surface that impart the greatest forces upon one another.
When a surface is wet with water, as one example, and a shoe is impacting upon that surface, the water will tend to be displaced away from the force. However, water has surface tension, which maintains the water in a position. Accordingly, if a flat material, for instance a flat soled sandal, impacted a flat wet (with water) floor, the water would resist dispersion from the floor upon contact by the flat soled sandal. This would retain the water under the sole and thus the flat soled sandal would be more likely to slide on the surface than if the flat soled sandal was in contact with a dry surface, thus leading to a fall.
Accordingly, it is the goal of the slip resistant shoe to move the water away from the lugs on the sole and away from the points of contact between the lugs and the surface so that the lugs may contact the surface free of water, because the surface has a higher coefficient of friction when dry than when wet, thus preventing a slip or fall.
To move the water away, it is necessary to provide for water to be able to move away from the lugs and allow for contact between the surface and the lugs. The use of designs to channel water from the lugs provides for improved contact between the lugs and the surface. The mechanism is similar for other surfaces, i.e. oily surfaces, dusty surfaces, and other surfaces that have low coefficients of friction that result in opportunities for a slip and fall. In each case, by removing or channeling the slippery materials, greater slip resistance is imparted to the sole.
Accordingly, one embodiment of a slip resistant shoe sole is depicted by
Additionally situated on the toe 10 and heel 11 portions of the sole 1, are lateral lugs 14 that stretch the width of the sole 1. Being at the tail ends of the heel 11 and the tip of the toe 10, the width is smaller than at the widest portion of the sole 1. The lateral lugs 14, at the heel 11 portion of the sole 1, are often first in contact with a surface, and the lateral lugs 14 act to dispel, squeeze, or push liquids or other contaminants away from the surface. The lateral lugs 14 are progressively taller in height (as can be seen in
Further provided on the sole 1 are transverse (21 and 31) and longitudinal lines (22 and 32) that run through both the heel portion 21 and 22, and through the toe portion 31 and 32. These lines are cut through the otherwise regular and organized pattern of the pinwheel lug group 5, and provide channels for fluids or other material to be dispelled away from the lugs.
In view of
The height of the lugs depends on the particular use of the shoe, or boot. Lateral lugs 14 may have a height of about 0.5 mm to about 10 mm. Whereas the lugs on the forefoot pad 16 and heel pad 15 also have a height of about 0.5 mm to about 10 mm. The height of each of the lugs is the same in some embodiments. However, in other embodiments, the lugs vary in height, wherein the side or edges vary in height. Further embodiments have lugs that vary in height within a pinwheel lug group 5. Further depicted is that the base of each lug is wider than the top of each lug, thus creating a slight angle from the base of each lug to the top of each lug, and wherein the top of each lug on the forefoot pad 16 and the heel pad 15 has a generally pointed, not rounded corners. In certain embodiments, some lugs are rounded and do not have a sharp corner. For example the edge lugs 13 or lugs positioned near transverse or longitudinal lines.
Turing to a further description of an embodiment of the invention in view of
Each crescent lug 2 is about 3.5 mm in height, when not at the edge of the sole, and the lug groove 6 is about 1.5 mm in width. Each of the pinwheel lug group 5 is typically the same height. In some embodiments, it is advantageous to have the height of each of the crescent lugs 2 to be slanted, such that the narrow portion is lower in height than the bulbous portion. Or, alternatively, each of the three pairs of lugs in the pinwheel lug group 5 may be of different heights.
Each of the pinwheel lug groups 5 provides for three crescent lugs 2 arranged so that the bulbous end 3 of each of the three crescent lugs 2 is centrally aligned in the pinwheel shape, and the narrow ends 4, being aligned with the outer portions of the pinwheel shape. The shape provides for the ability of a liquid to be pressed around each of the crescent lugs 2, and to be expelled either around the crescent lug 2 or through the lug groove 6. In addition, the degree of sharpness of the profile of the lug further enhances the ability of a liquid to be pressed around each of the crescent lugs 2 and to be expelled either around the crescent lug 2 or through the lug groove 6. The nature of the design allows for channeling of water or other contaminant around the crescent lug 2 to provide for greater contact with the surface and less with the water or other contaminant on the surface.
Accordingly, as depicted, the crescent lugs in
It may also be advantageous to describe the arcuate or crescent shaped lugs by visualizing the lengths of particular segments. In particular, the arc length is longer for the outer length than the inner length, wherein the inner length is defined by the length of the segment at length α 51 when measuring from the highest point at each of the narrow and bulbous ends, wherein the outer length is defined by the length of the segments comprising lengths of 0, 13, A, and γ 52, 53, 54, and 55. The outer length is about 1.2 to about 8 times longer than the inner length, or about 2 to about 5 times longer than the inner length. Thus, the lugs have non-linear edges and defined by a groove 6 in each lug, wherein the crescent shaped lugs 2 are arranged into a pinwheel pattern group 5 comprising three crescent shaped lugs, and wherein said pinwheel lugs. In some embodiments the groove 6 extends from the base of the top of the lug 2 to the base of the sole. In other embodiments, the groove 6 extends to a depth of about 10% to about 90% of the height of the lug.
In a preferred embodiment, the sole 1 comprises a plurality of pinwheel lug groups 5 arranged in a regular pattern on the heel pad 15 portion of the sole 1 and on the forefoot pad 16 portion of the sole 1, but leaving a portion at arch 34 portion of the sole 1 void of pinwheel lug groups 5. In alternative embodiments, an irregular arrangement of pinwheel lug groups 5 may be featured on the sole 1.
In view of
For example, in view of
The various embodiments detail a shoe having a slip resistant sole. Ordinary materials for a shoe sole may be utilized, including elastic polymer(s) such as synthetic rubbers, natural rubbers, ethylene-vinyl acetate copolymers, polyurethane, polyvinyl chloride. Further materials may include polybutadiene rubbers, polyisoprene rubbers, styrene-butadiene rubbers acrylonitrile butadiene rubbers, nitrile rubbers, ethylene propylene rubbers, ethylene-vinyl acetate copolymer rubber, polyamide rubbers, polyether, polyester, polyurethane, polyuria-urethane, epichlorohydrin, silicon and polysulfide rubbers. polyurea-urethane
Other suitable materials may further include leather, plastic and plastic polymers, as well as natural materials such as cotton, wool, or other similar material, wood, and other fibrous materials. The sole may be secured to a midsole or other innersole or upper portion of a shoe directly, as is known to one of ordinary skill in the art. The sole may be manufactured as a single piece, wherein the lugs and the sole are either cast of manufactured in one piece, or manufactured in two or more pieces and/or steps wherein the materials for each piece may be the same or different.
In some embodiments it is advantageous to utilize different materials for lugs in certain positions on the sole, so that some of the lugs are made of a softer material, or a material that has a greater friction coefficient on a particular surface. However, there is a balance between use of soft material and hard materials in their wear and abrasion patterns that affect the useful life expectancy of a shoe. Furthermore, the density and DIN of a sole material affect the speed at which the material breaks down, but also impact the material's slip resistance. Finding an appropriate balance depends on the particular situation and it may be necessary, in some cases, to substitute a longer useful life expectancy for a shoe having greater slip resistance.
In some embodiments a pinwheel lug group 5 is replaceable on the bottom of a sole, such that pinwheel lug group 5 is interchangeable based on the particular nature of the surface to be encountered. Accordingly, an embodiment of the invention is a slip resistant shoe kit comprising a plurality of pinwheel lug groups 5 that may be inserted onto the shoe based on the needs of a user, in a similar manner as to how golf spikes or other cleats are replaced on some athletic shoes. The pinwheel lug groups are easily replaced with tools known in the art and as used with the golf spikes or other cleats.
Shoes utilizing the slip resistant pinwheel lug groups 5 may be incorporated into a portion of a sole of a shoe, or cover the entire sole of the shoe. Lugs are substantially disposed on the toe and heel portions of the sole and optionally on the arch portion of the sole. Where traction may be appropriate on the toe, heel, or sides of a sole, pinwheel lug groups 5 may be further incorporated so as to “wrap” the sole around the edge of the outsole. This provides that the pinwheel lug groups 5 may be on the side of the shoe, about or perpendicular to the pinwheel lugs on the bottom of the sole. For example, climbing shoes may require slip resistance treat on surfaces other than the bottom of the sole.
A test was performed comparing shoes utilizing the resistant sole as described herein compared to other shoes. Each of the shoes are compared against walking shoe and occupational shoe standards, which are listed as the intended minimum for slip resistance for these types of shoes. Shoes A, B, and C, do not use the sole of the invention described herein, whereas Test Shoe A, and Test Shoe B, both utilize the pinwheel lug group feature as described herein. The chart below identifies hardness, density, and DIN (measurement of how fast the sole will abrade) of the sole material. Also quantified is slip resistance on dry, wet and oily/wet surfaces (wet+7 drops of oil), wherein a higher number is increased slip resistance.
The tests were tested under the Mark II testing method corresponding to a minimum standard for walking shoes of a Coefficient of Friction (CoF) of 0.5 Dry, 0.5 wet, and 0.4 oily/wet. Whereas the standard for Occupational shoes using the Mark II standard is 0.7 for dry surfaces, 0.6 for wet, and 0.45 for oily/wet surfaces.
The test shows that both Test Shoe A and Test Shoe B performed at or better than the standards for occupational shoes. However, the results for the other three shoes tested demonstrate that, only shoe B (having a higher density material and the highest DIN of the shoes tested) met all three standards. Accordingly, a shoe having a hardness of 57 Shore A or less, a density of 1.20 g/cm3 or less and a DIN of 110.0 mm3 or less and at least a slip resistance CoF of 0.75 on a dry surface, 0.6 on a wet surface, and 0.48 on an oily wet surface is preferred. Such a shoe provides comfort, durability, but also slip resistance.
The invention now being fully described, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the appended claims.
This application claims priority to U.S. provisional application Ser. No. 61/903,253 filed Nov. 12, 2013, which is incorporated herein by reference in its entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4724624 | Duclos | Feb 1988 | A |
| D525017 | Ochoa | Jul 2006 | S |
| D534332 | McClaskie | Jan 2007 | S |
| 7310894 | Schwarzman | Dec 2007 | B1 |
| D564191 | Jensen | Mar 2008 | S |
| D669256 | Castellon | Oct 2012 | S |
| D674585 | Kubis et al. | Jan 2013 | S |
| D699421 | McClaskie | Feb 2014 | S |
| D717031 | Della Valle | Nov 2014 | S |
| D734931 | McCourt | Jul 2015 | S |
| 20030033734 | McMullin | Feb 2003 | A1 |
| 20080229625 | Frasson | Sep 2008 | A1 |
| 20090188132 | Fujikawa et al. | Jul 2009 | A1 |
| 20110247237 | Jara | Oct 2011 | A1 |
| 20110252669 | Kasprzak | Oct 2011 | A1 |
| 20130008059 | Sum | Jan 2013 | A1 |
| 20140208610 | Dirsa | Jul 2014 | A1 |
| 20150096195 | Bacon | Apr 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 1260704 | Sep 1989 | CA |
| 0367297 | May 1990 | EP |
| 0383489 | Aug 1990 | EP |
| 1762151 | Mar 2007 | EP |
| 2449906 | May 2012 | EP |
| 1999022614 | May 1999 | WO |
| 2000004802 | Feb 2000 | WO |
| Entry |
|---|
| “Preventing Slips and Falls: Slip Resistant Footwear”, Liberty Mutual, Loss Control Reference Note, LC 56407 R2, pp. 1-4, Sep. 2009. |
| “Slip Resistance Guide—Safety, protective and occupational footwear supplied into the European market”, SATRA Technology Centre. |
| Number | Date | Country | |
|---|---|---|---|
| 20160000183 A1 | Jan 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61903253 | Nov 2013 | US |
