Spring space shoe

#This invention is a spring shoe called herein a space shoe. Its sole is a structure constrained to compress without tilting; this structure is called herein the p-diamond. This optimally simple, anti-tilt, compressible structure comprises overlapping diamond and parallelogram linkages which constrain an upper plate from tilting as it moves vertically up and down with respect to a lower plate. The p-diamond has many applications where non-tilt spring systems are required, and it is an inexpensive alternative to telescopically guided spring systems. P-diamond applications include, but are not limited to, the space shoe, which also has a push-off means to allow natural foot action.

#The first embodiment of the space shoe is called herein a space shoe because most of the skeletal sole is free space rather than a solid, foam-filled structure. The springs of the space shoe act directly between the ground plate and the shoe plate; that is, these springs are located at shoe or sole level. The second embodiment of the invention is called a bow shoe; its bow spring is located at the shin level, or above, to minimize the device weight at foot level.

#The space shoe provides for the following improvements (referred to as S1-S3 with “S” for space shoe). (S1) It has an improved mechanism to capture both heel and toe impact energy and return all impact energy through the toe during the latter part of toe-off. (S2) It provides for optimal stability by constraining an upper shoe plate to not tilt with respect to a lower ground plate—via a linkage called herein a p-diamond linkage. Improvement (S2) is referred to herein as sole tilting. Improvement (S3) is that a natural running action is allowed—where this running action comprises both a natural roll-over from heel to toe and a push-off—with the wearer's metatarsal joint freely flexing and the heel lifting into the air during toe-off.

#FIG. 1 shows views of the main invention, a non-tilting compressible structure called p-diamond.

#FIG. 2 is a schematic side view of the space shoe showing various vertical and lengthwise springs located within the sole.

#FIG. 3 shows a side view of a p-diamond linkage indicating how lengthwise springs with the proper hard force curve can be used to achieve a constant force curve.

#FIG. 1 shows views of the main invention, a non-tilting compressible structure called p-diamond 11. Side-view FIGS. 1a and 1b show p-diamond 11 expanded and compressed. FIG. 1c is a front view and FIG. 1d is a top view. P-diamond 11 comprises one or more (two here) p-diamond linkages 9, rigidly connected by cross beams 13, and optionally covered by cover plates 21 on the top and the bottom. P-diamond linkage 9 comprises four diamond links 10, one top length link 23, one center length link 24, one bottom length link 25, and two end links 14—all of which are hingeably connected in the depicted configuration by link hinges 16. Top length link 23 and bottom length 25 optionally extend beyond link hinges 16 on either end, but the functional parts for p-diamond linkage 9, that causes the critical motion constraint of p-diamond linkage 9 to move with only one degree of freedom, requires only the parts between the link hinges 16. In total, these links form an 8-bar linkage which constrains upper frame 6 to move vertically (with no tilting) with respect to lower frame 4. In this embodiment, upper frame 6 comprises two top length links 23, cross beams 13 at the top, and cover plate 21 at the top. Likewise, lower frame 4 comprises two bottom length links 25, cross beams 13 at the bottom, and cover plate 21 at the bottom.

#FIG. 1a shows lengthwise spring 57 which resists any compression force on p-diamond 11; vertical springs 19 also resist external compression. An external compression force can be exerted at any point on and between the areas of upper frame 6 and lower frame 4. At the same time an expansion force can be exerted at any point on and between the areas of upper frame 6 and lower frame 4. Even though the compressive and expansive forces are not located in the same place, upper frame 6 will not tilt with respect to lower frame 4. This is the key feature of the p-diamond invention. The term “p-diamond” refers to the fact that the linkage comprises overlapping parallelograms and diamonds. The value of the invention is that this is the simplest structure using only hinges to achieve this particular constraint of one degree of motion, and hinges are the cheapest, lightest, most robust means to achieve guiding of spring mechanisms in many applications.

#FIG. 1 actually depicts several variations of spring systems. FIG. 1a shows lengthwise spring 57 (helical) acting between 1) the center cross bar 17 located at the cross beam at link hinge 16 connecting the outside (left) pair of diamond links 10 and 2) the center cross bar 17 between adjacent center length links 24. Note ths this second location could be anywhere along center length links 24. Diamond tether 59 limits the amount of compression. FIG. 1b shows the alternative of a generic vertical spring 19 resisting compression and stop 44 limiting compression. These can be helical springs 48 or spiral helical springs 50 (which can compress to the wire thickness).