1. Field of the Invention
The present invention relates generally to insoles for footwear, and, more particularly, to a multilayered insole having layers that compress to a particular percentage of full set over time.
2. Description of the Related Art
Cushioning insoles of various types are known for use in shoes, particularly for use in running shoes and other shoes and boots intended for athletic activities. Typically, these insoles take the form of one relatively thin layer of foam material that rests atop the outsole of the shoe, and are often removable for washing or replacement. They are inexpensive, and do not provide long-term comfort and support.
While commonly used, conventional insoles of this general type have proven less than ideal in several respects. Firstly, the top surface of the foam material is often given a pronounced contour in an effort to support and cradle the wearer's foot, but because the foam is intended mainly to cushion the foot, it typically lacks sufficient strength and firmness to simultaneously provide the necessary support for proper biomechanical function of the foot, particularly in the rear foot and arched areas. This problem is aggravated by the fact that most athletic shoes are a “soft sided” to a greater or lesser extent, i.e., the uppers are formed of cloth, vinyl, or other flexible materials that yield outwardly under pressure, thereby providing very little inward buttressing around the insoles. As a result, conventional contoured insoles tend to deform and compress downwardly an outwardly under the foot without providing any meaningful level of support and also tend to break down and lose their shape rapidly in use.
Some efforts have been made to correct these problems by including higher durometer materials in one or more areas of the device. For example, some cushioning insoles have been constructed with a brand of heavier durometer rubber or similar material added in the arch area and around the heel of the foam foot bed. However, these materials have done little if anything to increase the strength or durability of the insoles, and they have not had the strength or configuration necessary to provide proper support for the wearer's foot.
One insole that has been tried is disclosed in U.S. Pat. Nos. 6,070,342; 6,233,847; and 6,618,960, each issued to Brown, and which are not admitted to being prior art by their mention in this background section. The patents disclose an insole made of a soft, cushioning foam blank and a substantially rigid yet flexible U-shaped end cap that buttresses the heel portion and has flanges that support other areas of the bottom of the blank. The blank used in that invention may take a hard set after time, eliminating its cushioning ability. Otherwise, the blank may not set at all so that the foot cannot be supported firmly in place when the insole is in use.
Podiatrists can also make prescription orthotics for people who suffer from foot maladies. This is the most expense option, which sometimes does not result in a comfortable or usable product.
What is needed, therefore, is a multi-layered insole that supports the foot, provides impact resistance, and conforms to the shape of the foot for comfort and does not require a doctor's prescription.
A multi-layered insole that supports the foot, provides impact resistance, and conforms to the shape of the foot and does not require a doctor's prescription comprises a pliable yet supporting heel cup layer, a high impact foam layer that sets very little, and an image foam layer that sets to the wearers foot shape thereby forming a custom fit to the foot bed. These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawings.
FIG. 1 is a plan view of a left foot insole according to the present invention.
FIG. 2 is a side elevation of the insole of FIG. 1.
FIG. 3 is a cross section view of the insole of FIG. 1.
The invention is a multi-layered insole that supports the foot, provides impact resistance, and conforms to the shape of the foot. It comprises a pliable yet supporting heel cup layer, a high impact foam layer that sets very little, and an image foam layer that sets to the wearers foot shape thereby forming a custom fit to the foot bed. It also can have an abrasion-resistant lining adapted and selected to transport moisture away from the foot. The present invention fills the niche between single layer insoles that provide little support and expensive prescription orthotics. The insoles of the present invention are long-lasting and cost much less than prescription orthotics. No prescription is needed because the insoles are trimmed to fit the shoe, and the insole conforms perfectly to the foot by wearing it for several hours, enabling the layers of materials to set to different percentages depending on the layer material selected.
Turning to FIG. 1, the insole 10 substantially fills the foot bed of an existing shoe or boot. If an insole is too big as purchased, it can be trimmed to fit. The left foot insole 10 is shown, and the right foot insole, being a mirror image of the left, is not shown. From this view in FIG. 1, one sees the heel cup 30 surrounded by an outside raised portion 40 that wraps around the heel to the outside of the foot and ends at a line 100 just short of the ball of the foot. An inside raised portion 20 conforms to the inside part of the foot, and provides arch support. Likewise, the inside raised portion 20 wraps around the heel to the inside of the foot, ending at a line 100 just short of the ball of the foot.
FIG. 2 shows the side elevation of the insole of FIG. 1. It can be seen at the front part of the insole that it is thin and therefore is suitable for inserting into many kinds of shoes and boots. The part of the insole in contact with the outsole of the shoe is the impact foam layer 50. Over that, but only from line 100 to the heel is a torsion stabilizing, anti-pronation heel cup 80. The heel cup 80 provides structure to the insole 10 and other layers so that the insole holds its shape.
Over the heel cup 80 and impact foam layer 50 is the image foam layer 60. The image foam layer 60 conforms to the user's foot to provide a custom fit to the foot bed. Optionally, an abrasion-resistant micro fiber lining 70 can be provided for rapidly transporting moisture and perspiration from the foot. The properties of the various layers are explained more completely in the discussion of FIG. 3.
FIG. 3 is a cross-section view of the insole 10. The layers are shown thicker than in reality for purposes of illustration. The bottom layer is the impact foam layer 50. It is preferably made of ethyl vinyl acetate. This high-density foam provides an approximately 20% set to the user's foot after several hours of wear. This still leaves about 80% of the original thickness that will not flatten down to almost non-existence, which is a major problem found in the prior art. The function of the impact foam layer 50 is to reduce shock and create a comfortable, cushioned environment in the shoe that helps protect joints from injury. The heel portion 90 of the impact foam layer 50 is shaped to conform to the heel pocket of a shoe.
The torsion stabilizing, anti-pronation heel cup 80 is preferably made of low-density polyethylene plastic. The function of the heel cup 80 is to improve balance and stability, thereby providing maximum support from torsion distension stress. Rolling one's foot in or out on a regular basis will actually wear down one side of a shoe or the other. This rolling can cause injuries to the ankles, heels, arch, shins, knees, hips, and spine. The heel cup 80 is designed to be pliable and flexible, yet strong enough to keep the user's foot in the neutral position.
The image foam layer 60 is preferably made of cross-link polyethylene. Many of the insoles of the prior art are made only of this layer. The image foam of the present invention is selected to take about an 80% set and forms a custom fit to the foot bed after wearing the insole for several hours. After several hours of wear, one will actually see the pressure points where the foot is compressing the boot bed at the toes, metatarsal, and heel. One of the great advantages of the present invention is that the user will have the dense cushioning of the additional layer of the impact foam 50 after the image foam layer 60 sets and customizes itself to the foot. The custom fit greatly enhances comfort, and prevents the foot from sliding and chaffing in the shoe, especially when used with the micro fiber lining 70. Preferably, the lining 70 is also treated to eliminate or reduce the presence of bacteria, fungus, and odors.
There are three embodiments envisioned that all have the same elements. The embodiment labeled the COMPETITOR, a trademark of Pro-Formance Industries, Inc., is adapted for cleated, running, athletic, and multi-use footwear, as well as for ski boots and snowboard boots. The COMPETITOR is designed to handle the most demanding athletic applications, and is noted by a high arch support system and raised area 20.
The embodiment labeled the ACHIEVER, also a trademark of Pro-Formance Industries, Inc., is adapted for work, casual boots, mid-range hikers, walking shoes, athletic and multi-use footwear. Developed for the active needs of people on their feet all day, the ACHIEVER features a medium-sized side raised portion 20 and heel cup. It provides support in the arch and metatarsal, prevents fatigue, and supplies comfort and support all day.
The embodiment labeled the EXPEDITION, also a trademark of Pro-Formance Industries, Inc., is adapted for hiking boots, ski and snowboard boots, court shoes, athletic, and casual footwear. It features a low raised portion 20 accommodates the deep heel pockets of quality hiking boots as well as the fitted form of golf, semi-dress, and casual shoes.
To make the multi-layered insole, individual layers, including the micro fiber lining 70, are adhered to each other in a process called flame lamination, where each layer is slightly melted by flame, welding each material to the next.
One alternative to the user wearing the insoles for several hours to set the layers is to warm them with an external heat source prior to wearing them. This feature is beneficial for running, hiking and ski shops because it allows the shop to create a custom fit for the customer much more quickly than when first used without external heat.
While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.