|Publication number||US20080271339 A1|
|Application number||US 11/743,478|
|Publication date||Nov 6, 2008|
|Filing date||May 2, 2007|
|Priority date||May 2, 2007|
|Publication number||11743478, 743478, US 2008/0271339 A1, US 2008/271339 A1, US 20080271339 A1, US 20080271339A1, US 2008271339 A1, US 2008271339A1, US-A1-20080271339, US-A1-2008271339, US2008/0271339A1, US2008/271339A1, US20080271339 A1, US20080271339A1, US2008271339 A1, US2008271339A1|
|Inventors||James R. Fischer|
|Original Assignee||Fischer James R|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (1), Classifications (11)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This invention relates to an extruded cushioning insole for footwear and a process of making the same, the insole having an integral construction, a crush resistance and resilience to provide effective cushioning for the useful life of the footwear.
The human foot is a complicated structure with many bones, muscles and tendons. People that are on their feet for long periods of time recognize the benefit of a shoe or shoe insert that provides a degree of cushioning to absorb the constant weight and pounding experience by their feet throughout the day. This cushioning is particularly appreciated when a person is on a hard surface such as concrete floor, sidewalk or road. Yet, the bottom of the foot is not flat, and includes a heel, arch, ball and toes to form an undulating surface. This structure creates areas of high or concentrated pressure and forces and areas of lower pressure and forces. Areas of the foot that experience higher pressures can tire and become sore more quickly.
Shoe insoles and inserts are typically placed over the sole or mid sole of a shoe, and engage the bottom of the foot to provide two types of cushioning. First, the insert should dissipate the shock of any dynamic forces experienced by the foot when the shoe strikes the ground, such as when a person is walking, running or jumping. Instead of sudden jarring impacts by the foot against the sole of the shoe, the forces are more gradually transmitted as the insert compresses. Second, the insert should distribute forces and pressures more evenly across the bottom of the foot. Lower portions of the foot compress the insert more than higher areas of the foot so that the insert tends to engage the entire bottom surface of the foot, and distribute pressure more evenly across that surface. This cushioning takes place even when the person is standing still.
A problem with cushioning insoles and inserts is their short useful life. The useful life of the insert is typically shorter than that of the associated footwear in which they are placed so that the inserts need to be periodically inspected and replaced. While conventional inserts have a typical useful life of one to six months, tennis or jogging shoes have a typical or normal useful life of about six months to two years and dress shoes and boots have a typical or normal useful life of about one to five years depending on a variety of factors such as the quality, craftsmanship and materials used to make them, the frequency they are worn, the environment in which they are worn, the activity level and degree of ruggedness when worn, the care given them, and the weight and perspiration of the wearer. Yet, consumers either forget to inspect their inserts, or are ill-equipped to determine when they should be replaced. Many people simply put inserts in their shoes and forget about them. If they do think to inspect the inserts, they have difficulty determining their unloaded thickness and compression resistance when the inserts are inside the footwear. People do not take the time to regularly remove the inserts from their shoes, and properly inspect them. Moreover, even when the inserts are removed, the inspection is more a matter of guesswork than an informed decision. A person may not have a new insert to use as a reference for comparing the shape and thickness of the used insert. People simply guess if the insert looks like it is crushed too much. Even if there is an available reference, they have difficulty visually gauging the percentage of recovery remaining in the insert or the degree to which it has been permanently crushed. The sides of the insert can retain their original cushioning shape and thickness while middle areas that experience the higher pressures can be significantly crushed so that its cushioning effectiveness is significantly reduced or lost. In addition, even if the insert does return to its original thickness, the insert may have lost its compression resistance or load bearing capacity. For example, foam is typically measured in units of indentation load deflection (ILD) or indentation force deflection (IFD). Although many consumers are not even aware that this type of cushioning loss can occur, those that are still likely to rely on guesswork in evaluating the degree of this cushioning loss. Testing labs with expensive machines are typically used to measure compression resistance. As a result, consumers continue to wear their cushioning inserts well after they deteriorate and perform ineffectively. Even though people buying cushioning inserts believe they are taking measures to improve their health, they can still end up with and suffer from chronic foot, ankle, knee, hip and back problems.
Cushioning insoles and inserts come in a wide range of structural complexity and price. Less complex and expensive inserts include a single sheet of resilient foam. Initially, the foam sheets help dissipate impact forces from running, jumping and walking, and also help distribute forces more evenly across the bottom of the foot such as when the person is standing still. However, as these foam sheets are compressed by the weight of the person, and repeatedly cycled as the person shifts their weight from one foot to the other, the sheets quickly lose their cushioning effectiveness. The sheets experience a loss in unloaded thickness due to crushing, particularly in higher pressure areas. The sheets can also experience a loss in compression resistance as measured in ILD/IFD. Significant cushioning losses can occur within a few months. The rate at which the inserts lose their cushioning effectiveness increases with the weight and activity level of the person. Yet, the feet and joints of heavier and more active people benefit the most from a proper cushioning insert. Consequently, although these less complex cushioning inserts are generally affordable, they are ill-equipped for many, if not most, people.
More complex insoles or inserts typically include multiple pieces of material. Each piece is separately formed. Individual pieces may be made of different materials such as metal, rubber, plastic, cloth fabric, foam or gel, and are shaped for a specific purpose. Some pieces are for areas that experience higher pressures, such as the heel or ball of the foot. Some pieces are made to provide structural support or stability, such as an arch support. The various pieces are then matched, placed in their desired orientation, and glued or otherwise attached to each other. The manufacturing process for more complex inserts require more inventory, materials, labor, equipment and time. An example of such an insert is disclosed in U.S. Pat. No. 4,674,204, the disclosure of which is incorporated by reference. Accordingly, the cost of these inserts is significant. Many people do not see the value of the inserts, and avoid using them until they begin suffering from chronic foot, knee or back pain. Unfortunately, the time for the preventing these ongoing daily ailments has passed.
Some inserts include a gel in an elastic or stretchable material to provide cushioning. A problem with these inserts is leakage and cost. A gel leak can stain, gunk up or otherwise ruin the footwear. Contact with liquid gel can also cause skin irritation for some people. Yet, the insert is exposed to heat and sweaty acids that can break down the material containing the gel or cause the gel to tear or otherwise deteriorate. These insets must also endure prolonged cyclical loading and unloading without leaking or deteriorating. Trimming gel inserts is not typically suggested, and can result in a leak of a liquid gel insert. Thus, many people avoid these types of inserts because of possible leaks, gel deterioration, damage to the footwear and the cost of the insert.
A further problem with cushioning insoles and inserts is adaptability. The inserts should be easily adaptable for use in a wide variety of footwear, such as walking shoes, dress shoes, boots, or tennis shoes. This is particularly problematic for more complex or multi-piece inserts. These inserts can include metal or hard molded pieces that are not generally intended to be cut or trimmed. They can also include a cloth fabric that will unravel if cut or trimmed. Other inserts are contoured with a raised perimeter around the heel and arch regions sized for a specific foot having a specific width. The contoured perimeter is not intended to be trimmed, and restricts the movement of the foot in the footwear. As a result, the inserts have a defined “take-it-or leave-it” shape that is not adaptable to the shape of a specific shoe, boot or sneaker. Forcing an insert that is too wide or too long into footwear can kink the insert or shoe and result in discomfort, and damage the shoe insert. Inserts that are too narrow or short relative to the shoe can shift inside the shoe and result in similar problems.
A still further problem with cushioning inserts is that they do not accommodate a wide variety of people. While people come in all shaped and sizes, inserts are often designed for the “average” person. If the insert is contoured to the shape of a foot, the contouring is for the foot of the average person. The thickness and stiffness or rigidity of the insert is also intended for a person of average weight. The inserts are not intended for children or petit or larger adults. Heavier people will bottom out the insert, which reduces the effectiveness of the insert and can damage the insert and reduce its life. Lighter people do not compress the rigid material significantly, which reduces the cushioning effect of the insert.
A still further problem with insoles and inserts is that they inhibit the flexibility of the foot and shoe. Components that are intended to be stiff or rigid to provide an arch support or absorb shock tend to resist bending.
A still further problem with insoles and inserts for footwear is quick recovery. To perform properly, the insert must quickly return to its normal or unloaded position so that it is ready to provide cushioning for the next step or jump of the person. Yet, many materials have a recovery rate that is too slow for the pace of a person that is walking or running.
A still further problem with conventional insoles and inserts is odor absorption. Inserts with cloth of leather materials will absorb the sweat and odors of the feet. Some foam inserts also tend to absorb moisture and odor. These inserts will have to be disposed of for sanitary or hygiene reasons before the complete cushioning life of the insert.
A still further problem with cushioning insoles or inserts is heat and sweat resistance. The inserts should be made of materials that withstand prolonged exposure to body heat and sweat. The recovery rate and compression resistance of the material cannot deteriorate when exposed to the heat and sweat of the human body.
A still further problem with cushioning inserts is that they should not contribute to the growth of mold and bacteria in the shoe. The structure of the insert should not collect moister, so as to cultivate the growth of mold and bacteria. Yet, many inserts have a flat bottom surface that can trap moisture. The overall structure of the insert does not allow the materials below the insert to breath and dispel the moister that cultivates mold and bacteria.
The present invention is intended to solve these and other problems.
The present invention pertains to an extruded cushioning insole or insert for footwear. The insole disperses the weight of an individual more evenly across the surface of their foot and reduces the impact forces on the feet when walking, running or jumping. The insole or insert is an integrally extruded, one-piece insert. One insole embodiment includes a flexible upper pad with a plurality of downwardly extending tubes that each form a collapsible chamber. Another insole embodiment has a solid main body with a flat upper surface and a contoured lower surface formed by thinner and thicker regions of the insert. Another insole embodiment has a flat upper surface and a convex lower surface formed by a collapsible internal disc-shaped chamber. The convex surface is generally flat when compressed.
An advantage of the present extruded plastic cushioning insole or insert is its long life. Its useful life is typically longer than that of the associated footwear. The FPVC plastic material retains its compression resistance and resiliency for a relatively long period of time, even when used by a relatively active or heavier person. The insole should not need to be periodically removed from their shoe, inspected and replaced. When consumers throw away their old shoes or boots, they simply remove the inserts, and insert them in a new pair of footwear. The replacement of the footwear triggers the inspection of the inserts. The consumer does not have to independently remember to inspect the inserts during the life of the footwear.
Another advantage of the present extruded cushioning inserts is ease of inspection. Prior to placing the inserts into a new pair of shoes, the inserts are visually inspected to determine if they have retained their proper shape. The extending tubes have a uniform structure when the insert is in good working condition. Non-uniformity caused by crushing of the tubes in the more central, high pressure areas is easily noticed. The inserts should be replaced when portions of the tubes lose their resilience, and fail to quickly return to their fully extended position and uniform configuration.
Another advantage of the extruded cushioning insole or insert is its ease of manufacture and economical price. The cushioning inserts are formed by a single extrusion process and a punch press. No separate pieces need to be matched and glued or otherwise secured together. Inventory, logistics, material costs, labor, equipment and time are kept to a minimum. The extruded inserts are made of solid materials and contain no substances that can leak or create a mess. By keeping the cushioning inserts economical, many people will begin using them before they start to suffer from chronic foot, knee or back pain.
A further advantage of the present extruded cushioning insole is its adaptability. The insoles or inserts are easily adapted to obtain a proper fit inside a variety of footwear, such as walking shoes, dress shoes, boots, or tennis shoes. Although feet and footwear come in all shaped and sizes, the uniform structure of the integrally extruded inserts and their use of soft FPVC plastic material allows them to be easily cut and trimmed to fit a wide variety of feet and footwear. The cushioning inserts can be pre-cut for specific foot sizes such as for adults or children, and trimmed by the consumer prior to inserting them into their specific pair of shoes or boots. Cut or trimmed areas do not fray, unravel or otherwise deteriorate. As a result, the inserts are easily shaped to snuggly fit inside a wide variety of footwear, without kinking. The inserts remain fixed in place inside the footwear and do not shift around during use. The inserts should not cause foot sores or damage the footwear.
A still further advantage of the present extruded cushioning insert is its adaptability for persons of different weights. By simply increasing the thickness of the flexible pad, height of the tubes, or thickness of the deformable wall of the tubes, the inserts can accommodate the forces associated with wide variety of weights. The thickness and compression resistance of the insert can be selected to accommodate people weighing 30 pounds or 300 pounds. The inserts can be used by children or petit or larger adults. Heavier people do not bottom out the inserts made for them. Lighter people properly compress their inserts and receive the benefit of a sufficient amount of cushioning.
A still further advantage of the present extruded cushioning insole is its flexibility. The insole or insert is made of soft flexible PVC plastic and is free of metal and rigid parts that resist the natural bending of the foot and shoe. The compressible tubes can be positioned laterally to further increase flexibility and help the insert conform to the natural bending motion of a foot or shoe.
A still further advantage of the present extruded cushioning insole and insert is its quick recovery. The inserts quickly or instantaneously return to their normal or unloaded position so that it is ready to provide cushioning for the next step or jump of the person. The recovery rate of the insert is believed to be less than ¼ second, which allows for full recovery between each step even when a person is walking, running or jumping at a fast pace.
A still further advantage of the present extruded cushioning insole is its resistance to odor absorption. The extruded plastic insole or insert does not absorb the sweat and odors of the feet. The insert can be used for its entire useful life without needing to be disposed of for sanitary or hygiene reasons.
A still further advantage of the extruded cushioning insole is that it retains its integrity in the presence of body heat and sweat. The FPVC plastic withstands prolonged exposure to heat and sweat. The recovery rate and compression resistance of the material do not deteriorate when exposed to human body heat or sweaty acids.
A still further advantage of the extruded cushioning insert is that it does not contribute to the growth of mold and bacteria in the shoe. The structure of the insert does not collect moister, so as to cultivate the growth of mold and bacteria. The overall structure and uneven bottom surface of the insert allows moister to escape and the shoe to breathe in a normal manner.
Other aspects and advantages of the invention will become apparent upon making reference to the specification, claims and drawings.
While this invention is susceptible of embodiments in many different forms, the drawings show and the specification describes in detail several preferred embodiments of the invention. It should be understood that the drawings and specification are to be considered an exemplification of the principles of the invention. They are not intended to limit the broad aspects of the invention to the embodiments illustrated.
As shown in
The present invention pertains to an extruded cushioning insole or insert for footwear generally indicated by reference number 50 in
The insert 50 is formed by an extrusion and forming process including a conventional plastic extrusion machine 61 as in
A first embodiment of the insole or insert 50 is shown in
The tubes 80 project down from and are uniformly spaced across the lower surface 74 of the upper layer 70. Each tube 80 is formed by a continuous wall 82 having a uniform thickness of about 0.05 inch. The wall 82 is arcuate and forms opposed side portions 83 and a joining bottom portion 84. The upper layer 70 forms an upper portion or wall of the tube 80. The walls 83, 84 and 70 of the tube 80 surround a hollow interior that forms a longitudinal channel 90 with opposed vented ends 92 and 93. Although most tubes 80 and their channels 90 are continuous across the length of the insert 50, given the particular arcuate shape of the foot 10 and insert 50, some tubes 80 may be broken in the arch region 58, or cut open along the perimeter 53 of the insert. Each tube 80 has a height of about 0.25 inch, so the total uncompressed height of the insert 50 is about 0.3 inch. Each tube 80 has a width of about 0.38 inch, which is the distance between the outside surfaces of its opposed sidewalls 83. Each tube 80 is spaced a uniform distance apart of about 0.18 from its adjacent tube or tubes. This is the width of the spaced section 78 of the upper layer 70 between adjacent tubes 80. Each sidewall 83 forms a deformable wall that supports the upper layer 70. These tubes 80 and their deformable walls 83 are evenly spaced across the width of the insert 50.
This insole 50 is preferably made of FPVC plastic having a specific gravity of about 1.27 as per ASTM D792, and a hardness of about 75 durometers (instantaneous) and 66 durometers (15 seconds) as per ASTM D2240. The plastic has a tensile elongation at break of about 420%, a tensile stress of about 740 psi, and a tensile strength of about 1,800 psi as per ASTM D638, and a tear strength of about 270 lbs/in as per ASTM D624. The plastic has a Clash-Berg modulus or modulus of rigidity of about 18,000 psi as per ASTM D1043, and a compression set of about 23% as per ASTM D395. The plastic has a brittleness temperature of about −47° F. as per ASTM D746, an extrusion melting temperature of about 350° F., and a mold shrinkage of about 0.02 in/in as per ASTM D955. The FPVC plastic is available in pellet form from PolyOne Corporation of Avon Lake, Ohio under its “Geon” B7500 mark.
As shown in
The stiffness or resistance to compression of the deformable walls 83 resist this buckling to create a cushioning effect. The greater the buckling, the greater the amount of upward force exerted on the upper layer 70. In areas of lower pressure 110, the sidewalls 83 of adjacent buckling tubes 80 remain separated and do not touch each other. However, as the height of the tubes 80 is greater than half the distance between adjacent tubes, in areas of high pressure 115, the sidewalls 83 of adjacent tubes do touch each other. A sudden compression of the insert 50 and its tubes 80 will also cause the air inside the channels 90 to be forced out their vent ends 92. Although various embodiments of the insert 50 have a flexible upper layer 70 with the same general top profile view such as that in
A second embodiment of the insole or insert 150 is shown in
A third embodiment of the insole 170 is shown in
Insoles 150 and 170 are preferably made of FPVC plastic having a specific gravity of about 1.14 as per ASTM D792, and a hardness of about 55 durometers (instantaneous) and 50 durometers (15 seconds) as per ASTM D2240. The plastic has a tensile elongation at break of about 440%, a tensile stress of about 400 psi, and a tensile strength of about 1,100 psi as per ASTM D638, and a tear strength of about 180 lbs/in as per ASTM D624. The plastic has a Clash-Berg modulus or modulus of rigidity of about 1,000 psi as per ASTM D1043, and a compression set of about 20% as per ASTM D395. The plastic has a brittleness temperature of about −70° F. as per ASTM D746, an extrusion melting temperature of about 330° F., and a mold shrinkage of about 0.03 in/in as per ASTM D955. The FPVC plastic is available in pellet form from PolyOne Corporation of Avon Lake, Ohio under its “Geon” A5500 mark.
A fourth embodiment of the insole or insert 200 is shown in
A fifth embodiment of the insert 300 is shown in
The inserts 50, 150, 170, 190, 200 and 300 can be customized to meet the specific needs of an individual. The high pressure areas 57′ and 59′ in the ball and heel regions 57 and 59 are marked and cut away to relieve pressure in those areas as shown in
Although the tubes 80, channels 90 and their deformable walls 82-84 are shown extending longitudinally or from front-to-rear of the insert 50 during the process of manufacturing the inserts 50, the punch press 68 can be rotated 90° so that the tubes, channels and walls ran laterally or from side-to-side. For example, the tubes 80 and channels 90 of the insert 200 run from sided-to-side or laterally in
A sixth, solid profiled construction of the extruded cushioning insert 400 is shown in
In a eighth embodiment, the extruded cushioning insert 500 has a solid main body having parallel upper and lower surfaces 572 and 574, and a constant uniform thickness of about 0.17 inch as shown in
In an tenth embodiment, the extruded cushioning insert 600 has a main body 610 with opposed upper and lower surfaces 672 and 674 as in
While the invention has been described with reference to several preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the broader aspects of the invention.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US20110061263 *||Sep 15, 2010||Mar 17, 2011||Mafag-Reflexa Ag||Flexible insole for closed shoes|
|U.S. Classification||36/29, 12/146.00R, 36/44|
|International Classification||A43B13/38, A43B13/20|
|Cooperative Classification||A43B17/02, A43B13/206, A43B13/181|
|European Classification||A43B13/18A, A43B13/20T, A43B17/02|