Footwear energy harvesting system

[0001] This invention claims the benefit of U.S. Provisional Application No. 60/872,220, filed Dec. 1, 2006. U.S. Provisional Application No. 60/872,220, filed Dec. 1, 2006, is hereby incorporated by reference.

[0002] The present invention pertains to energy converters, and particularly to a capture and conversion of bodily motion to a form of energy.

[0003] The invention is a system for harvesting footwear energy, storing it, using it in an application, and/or converting it into another type of energy.

[0007] With increased use of power-consuming portable electronics, the need for compact and lightweight power sources in replacement of batteries appears to be a pressing issue. Energy harvesting from walking, in particular via the force and compression in the footwear soles, has the potential to deliver one to five watts average power with negligible interference with a normal human gait. There appears to be a very significant amount of available “waste” power from normal human activity. However, converting watt-level mechanical body or foot power to usable electricity or other kind of power by a miniature device integratable into body wear such as footwear is approached here in a new way. Many similar existing devices appear cumbersome, inefficient and consequently impractical.

[0008] The present invention is a system which may be based on an approach of transmitting the sole-compression pneumatically, for instance, to a high-speed microturbine (or micro turbine), or other pneumatic-to-mechanical converter, which in turn can drive a rotary electromagnetic generator, another energy converter, provide electrical or pneumatic energy to a storage mechanism, and so forth. The pneumatic-to-mechanical converter and the electrical generator in combination may be regarded as a pneumatic-to-electrical converter. The sole or other body wear compression may be transmitted to various energy converters or translators such as a massager or pump (not shown). Sole-compression may be transmitted as a moving fluid in one direction via a pneumatic rectifier to drive a component. An example kind of shoes which may be adapted for the present system may be running or tennis shoes. The term “present” refers to the invention herein. “Fluid” may refer to a gas or liquid.

[0009] The component may be a microturbine for driving an electrical generator to provide power to activate a mechanism for use, or a device for electrical storage. The electrical or electronic mechanism may be a cell phone, a PDA (personal digital assistant), a portable computer, body safety or navigation lights, a GPS (global positioning system) device, a warmer for hands, feet, or other portions of the body, various kinds of instrumentation, and so on. In one implementation, a foot warmer may include electrical heating elements formed in socks or built into shoes. A device, such as a chargeable battery or high capacity capacitor, may be provided electrical power by the microturbine-generator for storage. Power may be provided by the generator to both a mechanism and storage. For example, batteries of personal electronic devices may be charged. A common situation may be where some people spend much time on a cell phone while walking around and then frequently have to discontinue their call because of a low battery in the cell phone. With the present system connected to the phone, one could talk indefinitely while walking around to one or more destinations, whether at work or on time off. Whether the phone is being used or not, the cell phone battery may get charged up while walking or running, thus obviating a need to find a source of power, such as an outlet, to plug the phone in for a recharge.

[0010] The component may instead be a massager or other similar pneumatically drivable mechanism associated with a person such as the wearer to provide massaging or other physical therapy. The pneumatically powered massager or other mechanism may be in contact with the wearer's body in an applicable place or manner, such as the wearer's feet. Such massaging or therapy, for example, may used to reduce foot and/or leg fatigue of the wearer while walking. The massager or like mechanism may consist of one or more pneumatically inflatable and deflatable bags or pouches proximate to the feet and/or legs of the wearer, and have a pneumatic valve device to alternate filling and releasing a gas, such as air, to and from the pouches.

[0011] A pneumatically drivable pump may be connected to the present system and be used for moving fluids for one application or another, such as a pneumatic tool, gas storage under pressure, and so forth.

[0012] FIG. 1 is a diagram of an example system 10 of the present invention with a shoe 11 having a sole 19 with compressible chambers 12 and 13. Back chamber 12 at the heel of shoe 11 may have an output 14 and an input 15. When back chamber 12 is compressed, a gas 18 may be expelled through output 14 from chamber 12, particularly when a foot in the shoe 11 is putting weight on the heel of the shoe 11. When weight on the heel is removed, then chamber 12 may decompress and return to its original shape and internal volume. At the same time, gas 18 may return to chamber 12 through the input 15. Also at the same time, the foot in the shoe 11 may be shifting the weight from the heel to the toe and thus compressing chamber 13 and expelling gas 18 through an output 16. When the weight on the toe is removed, the chamber 13 may decompress and return to its original shape and internal volume. At the same time, gas 18 may return to chamber 13 through the input 17. Also at the same time, the foot in the shoe may be shifting the weight from the toe to the heel and again compressing chamber 12 thereby expelling gas 18 through output 14. Such heel-toe or back-front double action may continue to repeat itself indefinitely while a person with the foot is proceeding with an ambulatory motion or some other physical activity. Gas 18 may permit system 10 to operate at various temperatures.

[0013] FIGS. 2a and 2b are diagrams of back-front chambers 12 and 13 for double action shown in conjunction with a pneumatic rectification circuit or rectifier 20 and an energy conversion device 25. The double action may be referred to as front-back, heel-front, front, back, or the like. Chambers 12 and 13 may be embedded insole of shoe 11 and have elastomer walls which facilitate compressibility and decompressibility of the chambers.

[0014] When the heel chamber 12 is being compressed, as shown in the diagram of FIG. 2a, gas 18 may exit output line 14 and go through a check or one-way valve 21. From valve 21, gas 18 may flow into line or tube 26 to energy converter 25. Gas 18 is not necessarily able to flow through valve 21 towards chamber 12. Converter 25 may instead be an energy storage device or a combination of an energy converter and storage device.

[0015] When the heel chamber 12 is being decompressed, as shown in the diagram of FIG. 2b, gas 18 may be drawn in from energy converter 25 through line or tube 27 and to a check or one-way valve 22 and enter input line 15 to expanding chamber 12. Gas 18 is not necessarily able to flow through valve 22 away from chamber 12.

[0016] When the toe chamber 13 is being decompressed, as shown in the diagram of FIG. 2a, gas 18 may be drawn in from energy converter 25 through line or tube 27 and a check or one-way valve 24 and enter input line 17 to expanding chamber 13. Gas 18 is not necessarily able to flow through valve 24 away from chamber 13.

[0017] When the toe chamber 13 is being compressed, as shown in the diagram of FIG. 2b, gas 18 may exit output line 16 and go through a check or one-way valve 23. From valve 23, gas 18 may flow into line or tube 26 to converter 25. Gas 18 is not necessarily able to flow through valve 23 towards chamber 13.

[0018] FIG. 3 show the present system implemented in footwear. Even though two pieces of footwear are shown in the Figure, in some cases the system may be implemented in just one piece of footwear or only one shoe 11 per person. The present system might even be implemented with just one chamber. The system may be implemented in footwear for a kind of animal such as a horse.

[0019] In a typical walking step, the gas chamber 12 on the back (heel) may first be compressed during heel landing 31 as indicated in FIG. 3, and then the front chamber 13 may be compressed during the takeoff push 32. The force in both compressions is comparable to the body weight, and their duration may be about 0.5 to 1 second, depending on the walking speed. The peak pressure for a 72 kg (˜159 lbs) body weight and a 3×3 cm² (˜1.4 in²) compression area, may be about 784,500 Pa (˜114 psi). For a compression distance of 3 mm (0.118 in), the volume displacement may be 2.7 cm³ (˜0.165 in³), corresponding to 2.1 J (2.1 watt sec) per compression and 4.2 J (4.2 watt sec) per step. From this estimate, 1 W (1 J/sec) average power at normal walking (2 steps/sec) only needs a minimum conversion efficiency of 12 percent, which is a moderate goal.

[0020] The pneumatic rectification circuit 20 using four check valves 21, 22, 23 and 24 may direct the high pressure gas to a turbine 28 with a nozzle 29 for both compressions, so the turbine 28 is always driven in one direction. The turbine 28 may be connected to an electric generator 33 with a shaft 34. Electric current may be provided by leads 35 from the generator 33. The leads 35 may be connected to an electrical device 36 such as a cell phone, a PDA, storage, a computer, a light, or other item.

[0021] The microturbine generator unit 25, by virtue of its small size (i.e., about 1 inch in length and 0.5 inch or so in diameter), may be placed in various locations in the footwear 11, depending on overall requirements and other specifications. If the unit 25 is not in sole 19, a pneumatic connection may be made via small tubings 26 and 27 to other locations for unit 25. There may be other items (e.g., a pump for filling a pressure tank with another medium for reserve energy, a massager, pump, and so forth) which may be driven by pressured gas 18 from the footwear 11.

[0022] In the present specification, some of the matter may be of a hypothetical or prophetic nature although stated in another manner or tense.

[0023] Although the invention has been described with respect to at least one illustrative example, many variations and modifications will become apparent to those skilled in the art upon reading the present specification. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.