US 20060026864 A1
An ultra-thin liquid-filled insole interface for use in footwear is provided. The ultra-thin liquid-filled insole interface can be removable or fixed to an article of footwear, especially to protect against friction or shear forces.
1. An ultra-thin liquid-filled insole comprising:
a top substrate;
a bottom substrate; and
at least one ultra-thin liquid-filled cell interleaved between the top substrate and the bottom substrate, wherein the top substrate and bottom substrate are substantially identical in planar shape and adapted to be placed in an article of footwear as an insole; and wherein the top substrate, the bottom substrate, and the ultra-thin liquid-filled cell have a combined thickness is the range of the range of 0.5 mm to 2.0 mm, and wherein the ultra-thin liquid-filled cell has a thickness of less than 0.8 mm, and wherein the liquid has a relatively low viscosity.
2. The ultra-thin liquid-filled insole of
3. The ultra-thin liquid-filled insole of
4. The ultra-thin liquid-filled insole of
5. The ultra-thin liquid-filled insole of
6. The ultra-thin liquid-filled insole of
7. The ultra-thin liquid-filled insole of
8. The ultra-thin liquid-filled insole of
9. The ultra-thin liquid-filled insole of
10. The ultra-thin liquid-filled insole of
11. The ultra-thin liquid-filled insole of
12. The ultra-thin liquid-filled insole of
13. The ultra-thin liquid-filled insole of
14. An article of footwear comprising a liquid-filled insole comprising:
a fabric substrate; and
an ultra-thin liquid-filled cell affixed to a bottom surface of the fabric substrate, wherein the fabric substrate and the ultra-thin liquid-filled cell have a combined thickness in the range of the range of approximately 0.5 mm to 2.0 mm, and wherein the ultra-thin liquid-filled cell has a thickness in the range of 0.8 mm.
15. The article of footwear of
16. The article of footwear of
17. An insole packaged assembly comprising:
a pair of ultra-thin liquid-filled insoles, each liquid-filled insole comprising:
a top substrate; and
at least one ultra-thin liquid-filled cell coupled to a bottom surface of the top substrate, wherein the insoles are adapted to be placed in an article of footwear, and wherein the top substrate and the ultra-thin liquid-filled cell have a combined thickness in the range of the range of approximately 0.5 mm to 2.0 mm, and wherein the ultra-thin liquid-filled cell has a thickness less than 0.8 mm, both thickness measured when sufficient pressure is applied normal to a top surface of the top substrate so that both thickness are uniform; and
a packaging enclosing the pair of ultra-thin liquid-filled insoles.
18. The insole packaged assembly of
19. The insole packaged assembly of
20. The insole packaged assembly of
21. The insole package assembly of
22. The insole package assembly of
The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 60/598,363, filed Aug. 3, 2004, the content of which is hereby incorporated by reference in its entirety. The present application is also a Continuation-in-Part of and claims priority to U.S. patent application Ser. No. 10/142,353, filed May 8, 2002, which is hereby incorporated by reference.
Insoles currently exist to provide cushioning in articles of footwear such as shoes and boots. One type of insole is a removable insole that can often be purchased separately from the footwear article and used to replace an existing insole and/or to add additional cushioning. However, one problem associated with many such insoles is that they are usually padded, and thus, relatively thick. The added thickness often causes a wearer's foot to rub against the top and side inner surfaces of the shoe, boot or the like, which results in discomfort. Also, current padded insoles do not generally mitigate the negative effects of foot friction.
An insole that address one, some, or all of the problems associated with prior art insoles would have significant utility.
The present invention relates to an ultra-thin liquid-filled insole interface for use in footwear. An ultra-thin liquid-filled insole interface that is removable or non-removable is provided for an article of footwear.
In the embodiment illustrated, cell 102 is provided proximate first portion 101 of insole 100 to provide comfort to the ball of a foot, while cell 104 is provided proximate second portion 111 of insole 100 to provide comfort to the heel of a foot. One or both of cells 102, 104 can be provided in insole 100. As appreciated by those skilled in the art, the number of cells, as well as their size and shape can be adjusted as needed. Insole assembly 100 further comprises a top substrate 106, which is shaped and sized to fit into various articles of footwear as an insole, or portion thereof. Top substrate 106 can comprise a woven or knit textile fabric or a non-woven fabric such as natural or synthetic leather. Top substrate 106 can also comprise a moisture absorbing fabric such as terry cloth or other moisture management fabric.
Insole assembly 100 also can optionally comprise a bottom substrate 108 that is approximately identical in planar shape to top substrate 106. Bottom substrate 108 can comprise elastomeric materials such as but not limited to foam, rubber, or plastic. Top substrate 106 and bottom substrate 108 are typically affixed together with adhesive or affixing layer 113 such as formed with spray adhesives or lamination to sandwich and affix ultra-thin liquid filled cells 102, 104 therebetween.
Generally speaking, viscosity can be viewed as a measure of resistance to shear. Newtonian fluids, such as water or mineral oil, are unaffected by the magnitude and kind of motion to which they are subjected. Thus, Newtonian fluids have a constant viscosity regardless of the shear stress or shear rate applied. Water can be considered a low or relatively low viscosity liquid having a viscosity of approximately 1 cP at 273K (20° C.) and atmospheric pressure (about 1.0 atm). Generally, however, viscosity decreases (or loses resistance to shear) with increasing temperature.
It is known that shear viscosity can be a function of both shear force and shear rate in the following relationship:
“Shear flow” is an idealize type of liquid flow near a solid surface. In shear flow, the velocity of the liquid increases linearly with distance from the surface. At the boundary between the liquid and the solid surface, the velocity of the liquid is zero. Thus, in shear flow the boundary between the liquid and solid surface has often been called a “non-slip” boundary.
It is believed that with footwear, during walking or running, shear stress between the shoe and walking surface can be transmitted to the interface or boundary between the shoe and wearer's foot. Constant back and forth rubbing between the shoe and the wearer's foot during walking or running thus can subject the wearer to harmful shear stress and friction, which is often associated with foot pain and blisters.
It has been discovered that positioning a low viscosity liquid-filled insole or interface into an article of footwear reduces or mitigates the negative effects of shear force, stress, and/or friction on a wearer. It is believed that the low-viscosity liquid results in less shear stress being transmitted across the boundary between the shoe and the wearer, especially when compared with a solid cushioning insole (which does not flow) or a high viscosity liquid or gel (which is more resistant to flow). Thus, it is believed that lower transmitted shear stress results in greater comfort for the wearer, especially over a prolonged period of time.
In other embodiments, thickness 202, 208 is in the range of approximately 0.75 mm to 1.5 mm. It is noted, if desired, thickness 202 can be slightly larger measured at one of the liquid-filled cells 102, 104 compared with thickness 208, which is measured where an interleaved cell 102, 104 is lacking. Although insole 100 is quite thin, insole 100 provides remarkable comfort due to reduced friction transmitted to the foot. Importantly, however, insole 100 is ideally sufficiently thin to not cause additional discomfort from raising the wearer's foot to be in greater contact with the shoe cavity or box. Also, it is believed that a thicker cushioning can cause increased shear to the body of the wearer at least partially due to greater “hammocking” or bowing across the surface of the liquid-filled insole. Hammocking or bowing in a thicker cushion is believed to cause a larger component of shear applied to the foot due to normal forces (e.g. the wearer's weight) applied to the foot of the wearer.
In most embodiments, the in-fill liquid is low viscosity and has a range of approximately 0.8 cP to 1.2 cP at approximately atmospheric pressure and 20° C. In other embodiments, the viscosity closely resembles the viscosity of water. However, it is noted that the liquid should be selected so that it does not tend to permeate the material enclosing the liquid when place in normal use. Also, a liquid that does not readily permit mold, bacteria, or other growth would be advantageous.
It still other embodiments, insole 720 includes liquid-filled cell 102 positioned in first or ball portion 113 of insole 720 to provide comfort to the ball of the foot. Ball portion 101 includes ultra-thin liquid-filled cell 102. In these embodiments, insole 720 can be adapted to cover substantially the entire insole surface or truncated as illustrated as insole 730 to cover a front or ball portion of an article of footwear.
Finally, it is noted that although
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.