Abstract:
A modular article of footwear has a shock absorbing insert placed between the insole and the outsole thereof, for example at the heel. The insert includes a spring carrier having upper and lower portions, each having a plurality seats for receiving a respective ends of respective coil springs. Each of the springs extends between said upper and lower portions and is captured therebetween. A pair of opposed permanent magnets generates a separating force which supplements the supporting force of the mechanical springs. The insert may also contain a device for converting mechanical energy to electrical energy.

Description:
[0001]    This application is a continuation-in-part of application Ser. No. 14/330451 filed Jul. 14, 2014, which claims benefit of provisional application 61/957910, filed Jul. 15, 2013. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to shock absorbing footwear. 
         [0003]    Numerous footwear inventions have been proposed for absorbing shock and adding lift, particularly in the athletic shoe field. For example, U.S. Pat. No. 4,817,304 describes footwear with a cushioning sole structure in which a sealed internal member in the sole is inflated with gas to form a resilient insert in the heel region of the shoe. Various shoe structures have also been proposed in which springs are embedded in the shoe sole in the heel region or over the entire sole. See, for example, U.S. Pat. No. 5,502,901, No. 5,138,776, No. 4,566,206, and No. 4,592,153. Some of these structures are bulky and heavy, or cannot effectively be manufactured. My own patents (U.S. Pat. Nos. 5,502,901 and 7,213,350) describe improvements over those prior patents. 
         [0004]    One problem with prior shock absorbing footwear, including my own, is that the characteristics of the shock absorber, particularly including the load capacity, cannot be easily adjusted. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the present invention to provide new and improved items of footwear which have improved shock absorbing properties and which also add lift and propulsion to the foot of a wearer when walking or running. 
         [0006]    An object of the invention is to provide an article of footwear having an improved, easily replaceable, spring insert in the heel. 
         [0007]    Another object is to generate electrical power within the footwear as the user walks or runs. 
         [0008]    A further object is to provide a modular article of footwear, which can be quickly rebuilt, replaced, or modified by the wearer. 
         [0009]    These and other objects are attained by a shock absorbing footwear as described below. 
         [0010]    In this invention, a modular insert, containing two strong permanent magnets, is placed in a cavity in the heel of a shoe or boot. The magnets are arranged in magnetic opposition so that they are repelled from one another. The opposed magnets function as a magnetic spring, which acts in conjunction with mechanical (coil) springs to dissipate shock and add lift and propulsion to the wearer&#39;s foot in motion. 
         [0011]    The insert snaps into the heel cavity, so that it can be easily and quickly replaced, for example, for wearers of different weights. 
         [0012]    The coil springs and magnetic spring together are designed to support an air-flux gap within the sole member at all times. This permits continuous and more effective shock. dissipation than when the gap is closed, solid or absent under load. 
         [0013]    The coil springs and magnets work in conjunction to absorb and dissipate load or shock as the foot hits the ground. Subsequently, as the load shifts from the heel to the ball of the foot, both the coil springs and the magnets bias the opposing walls of the cavity apart, giving lift or propulsion to the wearer. 
         [0014]    The footwear may also include electrical elements which convert and store some of the mechanical energy generated by walking, Which would otherwise be absorbed or dissipated, into useful electrical energy. 
         [0015]    The shock absorbing insert of this invention may be used in any type of footwear, such as sports/athletic shoes, boots, casual shoes, work shoes, children&#39;s shoes, orthopedic shoes, sandals and the like. It significantly reduces shock to the body while walking, running or in other types of foot motion, and adds lift and propulsion, thereby reducing fatigue. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    In the accompanying drawings, 
           [0017]      FIG. 1  is an exploded perspective view of a first embodiment of shock absorbing footwear embodying the invention; 
           [0018]      FIG. 2  is a similar view of a second embodiment of the invention; 
           [0019]      FIG. 3  is an unexploded sectional view of the second embodiment, taken on a vertical longitudinal plane; 
           [0020]      FIG. 4  is a view of a spring insert assembly shown in  FIGS. 1 and 2 ; 
           [0021]      FIG. 5  is an enlargement of the portion of  FIG. 4  indicated by a circle; 
           [0022]      FIG. 6  is a top plan view of the insert assembly; 
           [0023]      FIG. 7  is a sectional view taken on the vertical center plane  7 - 7  in  FIG. 6 ; 
           [0024]      FIGS. 8, 9 and 10  are enlargements of the portions indicated in  FIG. 7  by respective circles; 
           [0025]      FIG. 11  is a perspective view of a portion of a debris shield shown in  FIGS. 1 and 2 ; and 
           [0026]      FIG. 12  is an enlargement of the portion of  FIG. 11  indicated by a circle. 
           [0027]      FIGS. 13-16  illustrate a modified form of the invention, which includes an electrical power generating and battery storage system. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    As shown in.  FIGS. 1 and 2 , which depict two embodiments of the invention, shock absorbing footwear embodying the invention includes an outsole  10 , an insole  20 , and an insert assembly  30 . 
         [0029]    The outsole  10  is preferably made of rubber, EVA, composite or polyurethane 
         [0030]    It has an open heel cavity or a similar cavity beneath the ball of the foot, approximately as wide as the heel or ball, 2.5″ for example.  FIG. 2  shows the heel cavity only, as an example. The reader will understand that the principles illustrated can easily be adapted to an insert placed beneath the ball of the foot (as suggested in  FIG. 1 ) rather than—or in addition to—at the heel location. 
         [0031]    The heel cavity has an opening on one side, e.g., toward to the arch or heel, approximately 3.0″ wide, for receiving the insert assembly. 
         [0032]    The outsole has a perimeter bead made of rubber, eva, composite or polyurethane. Alternatively, it may have multiple beads (upper and lower) to allow the insert to be manually pressed in the cavity while also allowing for easy removal and replacement. 
         [0033]    The footwear preferably also includes, between the insole and outsole, a midsole or footbed  25  made of modified cardboard or other suitable stiff material. The insole ( FIG. 1 ) or the footbed ( FIG. 2 ) has a hinged or flexible portion  27  which can be peeled back to allow access to the insert for removal or replacement. 
         [0034]    The insert assembly  30  includes a spring assembly  40  contained within a protective debris shield  60 . The spring assembly, best seen in  FIGS. 4 and 7 , includes a plate which has upper and lower portions  42 ,  44  joined along one edge by a living hinge  46 ; that is, the upper and lower plates are one continuous piece of material. The living hinge provides a preferred line of flexure between the upper and lower portions and allows the insert to be closed around the coil springs and magnets described below. The hinge and the upper and lower plates are preferably a single piece U-shaped molded part made of nylon or other suitable polymer. 
         [0035]    Each of the upper and lower plate portions  42 ,  44  is provided with a plurality of (preferably five or more) cup-shaped seats  48 , each designed to receive one end of a respective compression coil spring  50 , Each seat on the upper portion is aligned with a counterpart seat on the lower portion, along a longitudinal axis of the spring. Each seat has spaced walls  52 ,  54  defining an annular volume for securely holding the end of one of the springs. 
         [0036]    The spring seats  48  have beveled tops to prevent spring rub. The bottoms of the seats have protruding ribs that allow the spring to snap in, but hold the springs in place thereafter. 
         [0037]    Exemplary dimensions for each coil spring are 1.25″ length by 0.50″ diameter. The springs are preferably made of stainless steel; however, it should be understood that the choice of materials and exact dimensions may be adjusted to suit a particular situation. Furthermore, other types of mechanical springs, such as wave springs or Belleville springs, might be used instead of coil springs. The claims below use the generic term “mechanical compression springs” to cover all such alternatives. 
         [0038]    The seats  48  are preferably molded integrally with the plate portions  42 ,  44 , but they could alternatively be made as separate pieces. 
         [0039]    Upper and lower magnet canisters  55  are also formed in the plate, amid the coil spring seats  48 . The axis A-A ( FIG. 7 ) of each canister lies on the vertical center plane  7 - 7  ( FIG. 6 ) of the insert. The coil spring seats are arranged around the canisters, preferably at a uniform radial distance from the axis A-A. The insert preferably has snap-in feature to hold the magnet canisters in place. 
         [0040]    The preferred magnets  56  are two opposing thick nickel-coated rare earth permanent magnets of 35 MGOe (megagauss oersteds) or greater, Exemplary dimensions of each magnet are 1.0″ dia.×0.350″. 
         [0041]    It is preferred that the magnet spring and coil spring arrangement be able to support a load in the range of 100-600 pounds without coil binding. 
         [0042]    Before being installed in the outsole, the spring insert is placed within a debris shield  60  ( FIGS. 1-3 ) which provides some structural support and protects the springs and magnets from the elements (water, dirt, abrasive particles). The debris shield is a rubber or elastomeric polymer cover for the spring assembly; it is open on one end to receive the spring assembly. 
         [0043]    The debris shield preferably has a pair of pull tabs  58  that the user can grasp when removing the spring insert from the envelope. 
         [0044]    The insert assembly, normally securely seated in the recess in the outsole, can be quickly removed, for example when one desires to replace the insert with another having different spring characteristics, or to rebuild the inert by replacing the mechanical springs or the magnetic spring with parts having different spring rates of other characteristics. For example, the coil spring rates can be adjusted higher or lower around the perimeter of the insert. All the coil springs may have the same spring rate, or springs of different rates may be used to control pronation and supination for a particular wearer. 
         [0045]      FIGS. 13-16  shows a modified form of the invention, further including an electrical power generating and storage system. 
         [0046]    A heel insert utilizing two opposing 35 MGOe or greater permanent magnets  56  ( FIG. 7 ) further includes copper wire windings  60 ,  62  running from the top (12 o&#39;clock) of the permanent magnet to the bottom of the permanent magnet (six o&#39;clock). The windings arc situated on the flat faces of the permanent magnets, oriented 90° to the magnetic field between the permanent magnets. The windings are placed on a board in multiple layers, running both north-south and east-west. 
         [0047]    The number of windings determines the DC voltage output. As magnets move toward and away from one another in use, movement of the wire through the magnetic field induces alternating current in the windings. The wire windings lead to energy converting means such as an energy harvesting chip  64  which converts the alternating current to direct current. 
         [0048]    The preferred chip  64  is a low voltage device such as Texas Instrument BQ25570 Ultra Low Power Harvester Power Management IC, This device, which is available from Texas Instruments, Dallas, Tex., modulates and amplifies current induced in the winding. The BQ25570 chip can start at extremely low voltage levels (˜330 mV) and can continue to harvest energy all the way down to 100 mV, 
         [0049]    The generated current can be used immediately or saved in a storage device  60 , which may be a rechargeable battery or one or more supercapacitors. Presently, rechargeable lithium batteries are preferred as the most economical storage device. A stack of lithium coin batteries is illustrated in  FIGS. 15 and 16 ; other types of rechargeable batteries could be substituted. The batteries are placed in a container  68 . 
         [0050]    The windings may be made of copper or silver wire. Silver may be a better source, but the cost will be more. A copper winding can also capture the energy and would be a cheaper alternative. 
         [0051]    The chip should not be positioned in the magnetic field of the capture device, which should be separate or isolated on one part of the board. If the BQ25570 is placed in the magnetic field, there may be issues with noise. Preferably, therefore, a circuit board with the BQ25570 on it is mounted separate from the collection device. 
         [0052]    The BQ25570 is preferably connected directly to the output of the winding, but one should make sure that the voltage and current waveforms as the output of the winding are proper for the device. It may be necessary to use transorbs or the like to make sure that the voltage does not exceed the maximum voltage level of the BQ25570. 
         [0053]    Inasmuch as the invention is subject to variations and modifications, the foregoing description should be understood to be merely a preferred form of the invention defined by the claims below.