# Patent

## Title
Forefoot catapult for athletic shoes

## Abstract

An athletic shoe includes an upper, an outsole, a pair of hinged plates, and a spring. The pair of hinged plates are attached between the outsole and the upper in a forefoot portion of the shoe, and the spring biases the plates apart, so that energy is stored and returned during a propulsion phase of a gait cycle in a human step. Foam may be disposed between the plates. A shroud may enclose an outer periphery of the plates. An adjustable torsion spring may be disposed in a hinge portion of the plates, and one or more wave springs may be disposed between the plates.

## Background
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
This application claims the benefit of U.S. Provisional App. Ser. No. 61/168,533, entitled “Forefoot Catapult for Athletic Shoes”, filed Apr. 10, 2009, the entire contents of which are incorporated by reference herein.


BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the present invention relate in general to footwear, and particularly to energy absorption and return systems for use in athletic footwear.
2. Related Art
In prior U.S. Pat. Nos. 5,437,110 and 5,596,819, issued in the names of two of the inventors herein, a discussion was provided of the desirability of providing adjustable foot-strike energy shock absorption and return. Those patents disclosed the use of a device disposed in the midsole of a shoe under the heel. The device used an adjustable mechanism to store and return to the wearer's foot shock energy experienced during walking or running.
Those prior patents discussed a variety of related art, including U.S. Pat. Nos. 4,486,964, 4,506,460, 2,357,281, 2,394,281, 4,709,489, 4,815,221, 4,854,057, and 4,878,300 as disclosing a variety of spring systems for shoes that related to heel-strike energy absorption and return. Since the time of those patents, other patents and applications have addressed a variety of spring mechanisms for shoes. See, e.g., U.S. Pat. Nos. 6,282,814, 6,751,891, 6,865,824, 6,886,274, 7,159,338, 7,219,447, 7,287,340, and 7,290,354, as well as published applications 2005/0166422 and 2009/0064536.
A step forward or stride consists of a dynamic process sometimes referred to as gait. The science surrounding gait is extensive but embodiments of the present invention focus upon that aspect that a layman might identify as toe-off when jumping. Gait can be broken down into three distinct phases as follows: (1) the contact phase which begins with heel strike and continues until the foot is flat on the surface, (2) the mid-stance phase beginning from the foot flat and a shift of body weight and continuing until the heel rises, and, lastly, (3) the propulsion phase where toe-off (or jumping) would occur.
The related art does not focus upon the propulsion phase of the gait cycle. Most of the devices are directed to the contact phase and use heel-related mechanisms to store and return energy. Because energy stored in the contact phase via a heel spring is dissipated by the time the propulsion phase begins, heel springs have not proven effective for energy storage and return. Some of the related art also use springs under the ball of the foot. In addition to not being effective in the propulsion phase, such devices can have adverse physiological effects on the foot if not properly positioned.
SUMMARY OF THE DISCLOSURE
A catapult device in accordance with various embodiments of the present invention is located ahead of the ball of the foot and directly below the forefoot of the foot in a forefoot portion of a shoe. In various embodiments, the catapult device stores and returns energy during the propulsion phase of a gait. In some embodiments, the catapult device includes opposing plates hinged together and biased apart by a torsion spring that may be adjustable. Also, in some embodiments, lightweight foam is disposed between the plates. In other embodiments, additional springs, such as wave springs, or the like, may be disposed within or outside of foam at the front of the catapult device.
Such catapult devices are very effective in storing and returning energy where an athlete needs it most: at the front of the shoe, which is where the toe-off in running or jumping occurs. Furthermore, in various embodiments, the catapult device replaces a portion of the midsole that would otherwise be under the forefoot, and is thus easy to install in a production environment, as it simply is affixed to the outsole. The use of a torsion spring in various embodiments allows for easy exterior adjustability of the catapult device by a wearer of the shoe.
A shoe in accordance with an embodiment of the present invention comprises an upper, an outsole, a pair of hinged plates attached between the outsole and the upper in a forefoot portion of the shoe, and a spring biasing the plates apart, whereby energy is stored and returned during a propulsion phase of a gait cycle in a human step.
In various embodiments, the shoe further comprises foam disposed between the plates. Also, in various embodiments, the shoe further comprises a shroud enclosing an outer periphery of the plates. In some embodiments, the spring comprises a torsion spring disposed in a hinge portion of the plates. Also, in some embodiments, the torsion spring is adjustable.
In various embodiments, the spring comprises at least one wave spring disposed between the plates. In some embodiments, the shoe further comprises an energy return material disposed between the plates. In some embodiments, the energy return material comprises rubber or Hytrel®. In various embodiments, one of the plates wraps around a portion of the upper to form a toe bumper.
A device in accordance with an embodiment of the present invention is installed in a forefoot portion of a shoe between an upper and an outsole of the shoe, and is used to store and return energy during a propulsion phase of a gait cycle in a human step. In various embodiments, the device comprises a pair of opposing plates, hinge means for attaching the plates together at one end, and spring means for biasing the plates apart, whereby, when a wearer of the shoe moves into an apex of a gait cycle, a force applied on the plates pushes the plates together, increasing a loading of the spring means, and providing the wearer with a launch factor equal to a release of torque from the spring means.
In some embodiments, the spring means comprises a torsion spring. Also, in some embodiments, the spring means further comprises at least one wave spring. In various embodiments, the device further comprises means for precluding debris from entering an area between the plates. In some embodiments, the means for precluding debris from entering the area between the plates comprises foam. Also, in some embodiments, the means for precluding debris from entering the area between the plates comprises a shroud along a peripheral portion of the plates. In various embodiments, the spring means comprises an adjustment means for changing a force applied by the spring means to the plates to bias them apart.
A shoe in accordance with an embodiment of the present invention comprises an outsole having a heel portion, a ball portion, and a forefoot portion, and a catapult device comprising two plates and a spring, where the catapult device is located at least partially above the forefoot portion of the outsole. In various embodiments, the shoe further comprises a midsole, and the catapult device is located in a cavity in the midsole. In some embodiments, the spring is located between the two plates.
A method in accordance with an embodiment of the present invention allows for storing and returning energy during a propulsion phase of a gait cycle in a human step using a catapult device in a shoe including two plates and a spring that biases the two plates apart from each other. In various embodiments, the method comprises applying, with a foot, a force on at least one of the two plates that is positioned in the shoe beneath a forefoot portion of the foot, so as to move the two plates together and increase a loading of the spring, and launching the foot due to the two plates being moved apart by the spring as the foot is being lifted.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side view of a catapult device in accordance with an embodiment of the present invention when installed in an athletic shoe;
FIG. 2 shows a side view of a portion of a shoe in accordance with an embodiment of the present invention including a catapult device in an outsole of the shoe;
FIG. 3 shows a perspective view of a catapult device in accordance with an embodiment of the present invention;
FIG. 4 shows a top view of a catapult device in accordance with an embodiment of the present invention;
FIG. 5 shows a partial cross sectional view of a torsion spring mounting in a catapult device in accordance with an embodiment of the present invention;
FIG. 6 shows an alternative embodiment of a catapult device of the present invention, with a top part of the catapult device functioning as a toe bumper;
FIG. 7 shows an alternative embodiment of the catapult device including a shroud;
FIG. 8 shows an embodiment of a catapult device of the present invention;
FIG. 9A shows an embodiment of a catapult device of the present invention, with a wave spring augmenting a torsion spring;
FIG. 9B shows another embodiment of a catapult device of the present invention, with a wave spring augmenting a torsion spring;
FIG. 10 shows an embodiment of a catapult device of the present invention, with wave springs augmenting a torsion spring;
FIG. 11 shows an embodiment of a catapult device of the present invention, with wave springs augmenting a torsion spring;
FIG. 12 shows an embodiment of a catapult device of the present invention, with an energy return material augmenting a torsion spring;
FIG. 13 shows a side view of a portion of a shoe in accordance with an embodiment of the present invention;
FIG. 14 shoes a top view of a midsole having a cavity in which a catapult device is located in accordance with an embodiment of the present invention; and
FIG. 15 shows a flowchart of a method in accordance with an embodiment of the present invention.



DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIG. 1, an athletic shoe 5 is provided with a catapult device 10 according to an embodiment of the present invention. The catapult device 10 is mounted in an outsole 22 of the shoe 5, as shown in more detail in FIG. 2. The catapult device 10 includes a top plate 12 and a bottom plate 14 that are hinged together via a pin 18 (or similar means), as shown in FIG. 5. In various embodiments, the plates 12 and 14 are designed such that they have a very limited motion around a hinge axis. Also, in various embodiments, in a neutral position the plates 12 and 14 are parallel to each other, forming what might be explained as a duck-bill, as shown in FIGS. 3 and 4. In some embodiments, the plates 12 and 14 have a limited motion that allows movement toward one another but not opening beyond (any more than) the two plates being parallel to each other.
With reference to FIG. 1, various materials could be used for the plates 12 and 14, including polymer, block polymer, monomer, etc., that exhibit properties conducive to use in processes known as injection molding, and in some cases extrusion and the like, or other types of molding such as compression molding, etc. In various embodiments, material is selected for rigidity, because in practice the catapult device 10 will be subjected to tremendous force as a wearer goes through a gait cycle ending up on the balls of the feet. At the apex of the propulsion phase of the gait cycle, the catapult device 10 will be subjected to several times the wearer's body weight as the device is “loading”. During this loading, it may be desirable that the catapult device 10 does not deform under stress. Such deformity would result in loss of load factor resulting in diminished return of energy and a corresponding decrease in the actual intended performance. As such, thin steel is potentially usable to reinforce other materials to ensure the requisite rigidity.
A variety of hinge mechanisms could be used with the plates 12 and 14, such as a barrel hinge, butt hinge, living hinge, plain hinge, or others. In various embodiments, a barrel hinge can include molded features to control a movement of the plates 12 and 14 around its axis, to prevent it from springing open, such as a slot and key feature, or notched stop. A barrel hinge would form the two plates 12 and 14 into a single device with a single axis of rotation.
In various embodiments, a helical torsion spring 16 may encircle the hinge pin 18, and may bias the plates 12 and 14 apart consistent with a strength of the particular spring utilized. An embodiment including the helical torsion spring 16 is shown in more detail in FIG. 5. In various embodiments, the helical torsion spring 16 is constructed from a metal wire or rod twisted or formed into a helical coil. In such embodiments, each end of the coil may be biased against the plates 12 and 14. Such torsion springs may be similar to those shown in U.S. Pat. No. 5,464,197. That patent shows a coil spring member with arms that provide an opposing bias. Adjustment of the torsion is achieved therein via an inner coil which acts to control the deformation of an outer coil. If a hinge pin 18 is used, it could be positioned along line D as shown in the '197 patent. Alternatively, a torsion spring could be located within a barrel hinge formed as an integral member of the top and bottom plates 12 and 14. Once the catapult device has been properly assembled and installed within the forepart of the footwear, and the wearer moves into the apex of a gait cycle (i.e. toe-off in jumping), the force applied to the top plate 12 will push the two plates 12 and 14 together. This will increase the torque loading of the helical torsion spring 16, and provide the wearer with a launch factor equal to a release of torque from the helical torsion spring 16.
In various embodiments, between the plates 12 and 14 there can be lightweight foam 20, as shown in FIGS. 1-3. This component's purpose is basically as filler, and may extend partially (FIG. 8) or completely (FIG. 2) between the plates 12 and 14. In various embodiments, the catapult device 10 may perform optimally in a case where the space between the plates 12 and 14 is void or empty. However, given the normal spectrum of use for footwear, it might not be desirable to leave the space empty in many instances. Dirt, mud, water, snow, ice, etc. (debris) may find its way within the space and could significantly decrease or even destroy the function of the device. Therefore, various embodiments include a means of blocking debris from entering the working space between the plates 12 and 14. Because the catapult device 10 of various embodiments would perform optimally without any material between the plates 12 and 14, it may be desirable for performance reasons to include a material that is lightweight, reflects good tear strength values, and that possesses specific compression properties. In addition to the criteria above, the ideal candidate foam 20 in various embodiments would compress under very low loading and compress to 30% of original thickness gauge—or more. Based upon these criteria, the foam 20 would preferably be of an open cell type. Thus, polyurethane, rubber, rubber latex, PVC or polyethylene can be used in various embodiments.
One purpose of the foam 20 is to avoid debris collecting between the plates 12 and 14. The foam 20 may slightly inhibit the performance of the catapult device 10 in various embodiments, since it adds resistance in the loading phase of performance. As such, in an alternative embodiment of the invention shown in FIG. 7, the foam 20 may be replaced with a front shroud 30 on one of the plates 12, 14 (in FIG. 7, it is shown attached to the top plate 12). In various embodiments, the shroud 30 acts to keep debris from entering between the plates 12 and 14, and wraps around a perimeter of the toe area.
In addition, in various embodiments the foam 20 may be reduced in size or removed completely to allow the use of other springs 32, 34, 36 as shown in FIGS. 9A, 9B, 10, and 11. The springs 32, 34, 36 assist the torsion spring 16 in providing propulsion to the wearer of the shoe. In various embodiments, such additional springs could be wave springs as shown in U.S. Pat. No. 4,901,987, or the like. Wave springs are particularly advantageous because the energy return is almost entirely axial, which would serve to press the plates 12 and 14 apart after compression. The springs 32, 34, 36 could be attached directly to the top and bottom plates 12 and 14 in various embodiments. In various embodiments, an energy return or rebound material 48 may be disposed between the plates 12 and 14, as shown in FIG. 12. In some embodiments, the energy return material 48 comprises rubber, Hytrel®, or the like, and creates an additional energy return effect.
With reference to FIG. 9A, in various embodiments the top plate 12 and the bottom plate 14 are manufactured as separate units and may have portions in contact with each other at a contact location 85. With reference to FIG. 9B, in various other embodiments, the top plate 12 and the bottom plate 14 are manufactured as a single continuous unit.
As mentioned, in various embodiments the catapult device 10 is mounted to the outsole 22 under a forefoot region by conventional means (gluing, stitching, etc.) and replaces the midsole 38 in the forefoot portion of the shoe 5, as shown in FIG. 2. Thus, in such embodiments, the midsole 38 would extend only from the heel portion of the outsole 22 up to the catapult device 10. With reference to FIG. 2, the shoe 5 may be described with respect to different portions of the shoe 5 along a length of the shoe 5, including a heel portion 52, an arch portion 54, a ball portion 56, and a forefoot portion 58.
With reference to FIG. 1, in various embodiments, an optimal function of the catapult device 10 within the shoe 5 requires an absence of any material (foam/rubber/etc.) between the catapult device and the shoe upper 24. In other words, it is desirable in various embodiments to have the shoe upper 24 sit directly on the catapult device 10 in the forepart for best performance, as shown in FIG. 1. Therefore, in various embodiments the top plate 12 of the catapult device 10 would be configured to wrap up around the shoe upper 24 and in addition to its primary function of propulsion, forms features such as a toe bumper 26 and a sidewall 28, as shown in FIG. 6. Such a unique construction with the top plate 12 configured to wrap up around the shoe upper 24 would create a very rigid toe bumper 26 and sidewall 28, which would be a departure from typical basketball footwear.
With this approach, an alternative embodiment for the top plate 12 would have the top plate 12 manufactured from more typical, softer/flexible materials (rubber/foam/etc.) and a secondary component then added to it (e.g. steel) added to provide rigidity directly above the bottom plate 14. The bottom plate 14 in such embodiments may still be manufactured from the rigid materials.
FIG. 13 shows a side view of part of a shoe 6 in accordance with another embodiment of the present invention. The shoe 6 includes an outsole 22 and a midsole 38. In the shoe 6, the midsole 38 extends into a forefoot portion of the shoe 6. FIG. 14 illustrates a top view of the midsole 38 from FIG. 13 in accordance with an embodiment of the present invention, where the midsole 38 includes a cavity 39 in which an embodiment of the catapult device 10 is located. Thus, various embodiments allow for placing the catapult device 10 within a midsole 38, such as within the cavity 39 of the midsole 38 or otherwise surrounded by the midsole 38.
FIG. 15 illustrates a method in accordance with an embodiment of the present invention. In various embodiments, the method of FIG. 15 allows for storing and returning energy during a propulsion phase of a gait cycle in a human step using a catapult device in a shoe including two plates and a spring that biases the two plates apart from each other. In various embodiments, the method comprises (step 70) applying, with a foot, a force on at least one of the two plates that is positioned in the shoe beneath a forefoot portion of the foot, so as to move the two plates together and increase a loading of the spring, and (step 71) launching the foot due to the two plates being moved apart by the spring as the foot is being lifted.
The embodiments disclosed herein are to be considered in all respects as illustrative, and not restrictive of the invention. The present invention is in no way limited to the embodiments described above. Various modifications and changes may be made to the embodiments without departing from the spirit and scope of the invention. Various modifications and changes that come within the meaning and range of equivalency of the claims are intended to be within the scope of the invention.

## Claims

1. A shoe, comprising:
an upper;
an outsole;
a pair of hinged plates attached between the outsole and the upper in a forefoot portion of the shoe; and
a spring biasing said plates apart, whereby energy is stored and returned during a propulsion phase of a gait cycle in a human step;
wherein said spring comprises a torsion spring disposed in a hinge portion of said plates; and
wherein said torsion spring is adjustable.

2. The shoe of claim 1, wherein said shoe further comprises:
foam disposed between said plates.

3. The shoe of claim 1, wherein said shoe further comprises:
a shroud enclosing an outer periphery of said plates.

4. The shoe of claim 1, further comprising:
at least one wave spring disposed between said plates.

5. The shoe of claim 1, further comprising:
an energy return material disposed between said plates.

6. The shoe of claim 5,
wherein the energy return material comprises rubber or thermoplastic elastomer.

7. The shoe of claim 1,
wherein the plates are located entirely ahead of a ball portion of the shoe.

8. A shoe, comprising:
an upper;
an outsole;
a pair of hinged plates attached between the outsole and the upper in a forefoot portion of the shoe; and
a spring biasing said plates apart, whereby energy is stored and returned during a propulsion phase of a gait cycle in a human step;
wherein one of said plates wraps around a portion of said upper to form a toe bumper.

9. A shoe, comprising:
a device, installed in a forefoot portion of the shoe between an upper and an outsole of the shoe, and used to store and return energy during a propulsion phase of a gait cycle in a human step, the device comprising:
a pair of opposing plates;
hinge means for attaching said plates together at one end; and
spring means for biasing said plates apart,

whereby, when a wearer of the shoe moves into an apex of a gait cycle, a force applied on said plates pushes the plates together, increasing a loading of said spring means, and providing the wearer with a launch factor equal to a release of torque from said spring means;
wherein said spring means comprises an adjustment means for changing a force applied by said spring means to said plates to bias them apart.

10. The shoe of claim 9,
wherein said spring means comprises a torsion spring.

11. The shoe of claim 10,
wherein said spring means further comprises at least one wave spring.

12. The shoe of claim 9, wherein said device further comprises:
means for precluding debris from entering an area between said plates.

13. The shoe of claim 12,
wherein said means for precluding debris from entering the area between said plates comprises foam.

14. The shoe of claim 12,
wherein said means for precluding debris from entering the area between said plates comprises a shroud along a peripheral portion of said plates.

15. The shoe of claim 9,
wherein the device is installed entirely ahead of a ball portion of the shoe.