Removable shoe insole

Abstract

An insole liner for a shoe is disclosed. The liner consists of a wedge shaped member having opposite back and front ends, a top surface and a bottom surface. The liner has a polyurethane base layer, a middle layer made of silicone gel and a top layer made from memory foam. The wedge shaped member has a thickness which tapers from the back end towards the front end. The base layer has a shore hardness which progressively decreases from the back end of the wedge shaped member to the front end of the wedge shaped member and wherein the middle layer has a shore hardness which progressively increases from the back end of the wedge shaped member to the front end of the wedge shaped member. Finally, the bottom surface has a plurality of projections.

Claims

1. A removable insole liner for a shoe comprising: a. an integrally formed wedge shaped member having opposite back and front ends, a top surface and a bottom surface, the wedge shaped member having a base layer towards the bottom surface, a top layer towards the top surface and a middle layer interposed between the base and top layers; b. the base layer formed from polyurethane infused with particles of natural cork, the middle layer formed from silicone gel, and the top layer being formed from memory foam, the upper layer and base layer being integrally bonded to the middle layer; c. the base layer having a thickness which tapers from 2.5 cm from the back end of the wedged shaped member to 0.4 mm at the front end of the wedged shaped member, the middle layer having a thickness which tapers from 0.7 cm from the back end of the wedged shaped member to 0.6 mm at the front end of the wedge shaped member, the top layer having a uniform thickness of 6 mm from the back end of the wedge shaped member to the front end of the wedge shaped member, and d. the bottom surface having a plurality of projecting ridges.

2. The insole liner as defined in claim 1 wherein the particles of cork are between 2 mm to 0.1 mm in diameter, the particles of cork being interspersed throughout the base layer, the base having a cork concentration between 1% to 10% of the volume of the base layer.

3. The insole liner as defined in claim 2 wherein the cork concentration of the base layer is selected to give the base layer a shore hardness of between 35 to 55.

4. The insole liner as defined in claim 3 wherein the shore hardness of the base layer decreases from 55 at the back end of the wedge shaped member to 35 at the front end of the wedge shaped member.

5. The insole liner as defined in claim 1 wherein the base layer is configured to have a shore hardness which decreases from 55 at the back end of the wedge shaped member to 35 at the front end of the wedge shaped member.

6. The insole liner as defined in claim 5 wherein the middle layer is configured to have a shore hardness which increases from 3 at the back end of the wedge shaped member to 7 at the front end of the wedge shaped member and wherein the top layer has a uniform shore hardness ranging between 7 to 9.

7. The insole liner as defined in claim 1 wherein the base layer has a composition configured to give the base layer a shore hardness which progressively decreases from the back end of the wedge shaped member to the front end of the wedge shaped member and wherein the middle layer has a composition configured to give the middle a shore hardness which progressively increases from the back end of the wedge shaped member to the front end of the wedge shaped member and wherein the top layer is configured to have a substantially uniform shore hardness.

8. A removable insole liner for a shoe comprising: a. an integrally formed wedge shaped member having opposite back and front ends, a top surface and a bottom surface, the wedge shaped member having a base layer towards the bottom surface, a top layer towards the top surface and a middle layer interposed between the base and top layers; b. the base layer formed from a polyurethane plastic, the middle layer formed from silicone gel, and the top layer being formed from memory foam, the upper layer and base layer being integrally bonded to the middle layer; c. the base layer having a thickness which tapers from 2.5 cm from the back end of the wedged shaped member to 0.4 mm at the front end of the wedged shaped member, the middle layer having a thickness which tapers from 0.7 cm from the back end of the wedged shaped member to 0.6 mm at the front end of the wedge shaped member, the top layer having a uniform thickness of 6 mm from the back end of the wedge shaped member to the front end of the wedge shaped member; d. the base layer having a composition configured to give the base layer a shore hardness which progressively decreases from the back end of the wedge shaped member to the front end of the wedge shaped member and wherein the middle layer has a composition configured to give the middle a shore hardness which progressively increases from the back end of the wedge shaped member to the front end of the wedge shaped member and wherein the top layer is configured to have a substantially uniform shore hardness, and e. the bottom surface having a plurality of projecting ridges.

9. The insole liner as defined in claim 8 wherein the particles of cork are between 2 mm to 0.1 mm in diameter, the particles of cork being interspersed throughout the base layer, the particles of cork comprising between 1% to 10% of the volume of the base layer.

10. The insole liner as defined in claim 9 wherein the base layer is configured to have a shore hardness which decreases from 55 at the back end of the wedge shaped member to 35 at the front end of the wedge shaped member.

11. The insole liner as defined in claim 10 wherein the middle layer is configured to have a shore hardness which increases from 3 at the back end of the wedge shaped member to 7 at the front end of the wedge shaped member and wherein the top layer has a uniform shore hardness ranging between 7 to 9.

12. An insole liner for a shoe comprising: a. an integrally formed wedge shaped member having opposite back and front ends, a top surface and a bottom surface, the wedge shaped member having a base layer towards the bottom surface, a top layer towards the top surface and a middle layer interposed between the base and top layers; b. the base layer formed from a polyurethane plastic, the middle layer formed from silicone gel, and the top layer being formed from memory foam, the upper layer and base layer being integrally bonded to the middle layer; c. the wedge shaped member having a thickness which tapers from 4 cm at the back end of the wedge shaped member to 1.5 mm at the front end of the web shaped member, each of the base layer and middle layer having a thickness which tapers from the back end of the wedged shaped member the front end of the wedged shaped member, the top layer having a uniform thickness from the back end of the wedge shaped member to the front end of the wedge shaped member; d. the base layer having a composition configured to give the base layer a shore hardness which progressively decreases from the back end of the wedge shaped member to the front end of the wedge shaped member and wherein the middle layer has a composition configured to give the middle a shore hardness which progressively increases from the back end of the wedge shaped member to the front end of the wedge shaped member and wherein the top layer is configured to have a substantially uniform shore hardness, and e. the bottom surface having a plurality of projections.

13. The insole of claim 12 wherein the base layer has a shore hardness which varies between 55 and 35 and wherein the middle layer has a shore hardness which varies between 7 and 3 and wherein the top layer has a shore hardness of between 7 to 9.

Description

DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a perspective view of a shoe insole insert made in accordance with the present invention.

[0009] FIG. 2 is a back view of the sole insole insert shown in FIG. 1 with a user's foot resting thereon.

[0010] FIG. 3 is a side view, partly in cross section, showing the shoe insole insert being worn in a pair of shoes by a user.

[0011] FIG. 4 is a bottom view of the shoe insole insert shown in FIG. 1.

[0012] In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Referring to FIGS. 1, a shoe insole insert made in accordance with the present invention is shown generally as item 10 and consists of a wedge shaped member 12 having back end 14 and front end 16, bottom surface 18 and top surface 20. Member 12 consists of a three layered structure having base layer 22, middle layer 24 and top layer 26. The three layers are integrally formed and firmly bonded together so that there is no possibility of slippage between the layers. The thickness of back end 14 of member 10 is determined by the desired lift in the height of the person intending to wear the insole insert. Ideally, the thickness of back end 14 is approximately 4 cm or so, although it can be a little greater or a little thinner as desired. Base layer 22 tapers in thickness from approximately 2.5 cm at back end 14 to approximately 0.4 mm at the front end 16. Of course, the exact thicknesses of each layer (and of member 12 as a whole) can be preselected depending on the desired height of the insole insert. Middle layer 24 also tapers in thickness from 0.7 cm at back end 14 to 0.6 mm at front end 16. Again, the exact thickness of middle layer 24 can be preselected as required. The thickness of top layer 26 remains substantially uniform from back end 14 to front end 16, preferably in the range of 0.6 mm.

[0014] The hardness and firmness of the component parts of wedge shaped member 12 can be measured using a durometer to obtain a shore hardness. The shore A hardness is a measure of how hard or flexible molded rubber (natural or synthetic) products can be from very soft and pliable to very stiff and almost no flexibility. The relative shore A hardness of the different layers and how that hardness changes from the back of the insert to the front of the insert is a key aspect of the present invention. The base layer is made of a polymer material and is manufactured such that the shore A hardness of the base member decreases from back end 14 to front end 16. Preferably, the composition of base layer 22 is selected such that the base layer has a shore hardness of 55 A at end 14 and a shore hardness of 35 A at end 16. Middle layer 24 is made of silicone gel and increases in shore hardness from back end 14 towards front end 16. In particular, the shore hardness of middle layer 24 increases from 3 A at end 14 to 7 A at end 16. Top layer 26 is preferably made from memory foam and has a uniform hardness from end 14 to end 16 of between about 7 A to about 9 A. Therefore, the base layer and middle layer have opposite hardness profiles, making the base layer harder at the back end (where the user's heel will rest) and softer at the front end, while the middle layer will be softer at the back end yet harder at the front end. This permits the base layer to provide a firmer base for the user's heel while allowing the middle layer to provide more force dampening at that point. This maximizes comfort while at the same time providing a secure footing for the user's heel.

[0015] The base layer is made of polyurethane with up to 10% cork by volume. It has been discovered that polyurethane, by itself, for constructing the base layer leads to a finished product which is too hard to be worn comfortably for long periods of time. The elevated heel portion of the insole insert 10 (i.e. back portion 14) bares a great deal of weight when the user wears the insert inside his/her shoes. As a result, increasing the hardness of the heel portion can result in increased foot strain. The hardness of the base layer is an important factor in the overall comfort and usability of the shoe insole insert. It has been discovered that adding between 1% to 10% cork particles to the composition of the base layer decreases the hardness of the base layer sufficiently to produce an insert which is sufficiently firm to provide good support while providing increased comfort.

[0016] As seen in FIG. 4, the bottom surface 18 of the base layer is provided with a plurality of projections , such as ridges in a cross hatched pattern. These cross hatched ridges help the base of the insert to seat itself securely in the shoe and prevents the base layer from slipping against the shoe's insert. The raised projections (ridges) increases the frictional contact between the insole of the shoe and the bottom of the base layer, resulting in a firmer more secure footing for the user's foot. Any pattern of raised projections can be used, but a cross hatched pattern of ridges is best because it increases friction in any direction.

[0017] Referring now to FIGS. 2 and 3, as the user applies his/her weight via heel 28 onto member 12 of insole insert 10, top layer 26 and middle layer 24 deform slightly while base layer 22 does not deform (relatively speaking). As the user walks, heel 28 bares down hard onto back end 14 as the foot touches the ground/floor. Middle layer 24, being less hard then base layer 22 deforms and therefore absorbs much of the shock; however, the portion of middle layer 24 closest to back end 14 deforms the most exactly where the impact forces are greatest. The forward portion 30 of the foot in front of heel 28 then receives more weight as the user moves forward in the step. It has been discovered that the changing shore hardness profiles of the middle and base layers make for a much improved and more comfortable step. The base layer, being stiffer towards the back end 14 provides a firmer and more secure connection to the sole 32 of shoe 34 where the impact of the foot (i.e. the heel) is greatest. This effectively transfers more energy from the heel of the foot to the sole of the shoe and provides greater stability. The portion of the base layer closer to end 16 is softer and more flexible, thereby allowing the base layer to flex more easily at the front thereby preventing the front end of the insert from buckling or dislodging from the shoe, resulting in a more secure step. The base, middle and top layers, all being intimately and securely bonded to each other prevents the top and middle layers from shifting from side to side relative to base layer 22, also keeping the foot centered on top of the insert and decreasing the likelihood that the position of the foot on the insert will shift from side to side. This makes the insert more comfortable to walk with.

[0018] A specific embodiment of the present invention has been disclosed; however, several variations of the disclosed embodiment could be envisioned as within the scope of this invention. It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims