Shoe Construction Providing Spring Action

The present invention relates to an improved shoe construction which is particularly useful as a running shoe, training shoe or the like.

In general, running or walking involves a specific pattern or sequence of events insofar as the foot is concerned. In particular, the heel impacts the ground first, the weight then shifts forward onto the ball of the foot and next the forefoot and toe region provide the last contact with the ground as the foot is lifted from the ground. The initial impact in the heel area is of special interest with runners because, in general, it is desirable to absorb as much impact energy as possible, consistent with providing a stable landing and without slowing down the runner. A further consideration in a shoe construction of this type is that of actually enhancing the performance of the wearer by, e.g., providing built-in spring force that facilitates the weight shift mentioned above and also assists in propelling the foot off the ground.

A number of patents relate to shoe constructions which are variously designed to address one or more of the issues discussed above. For example, U.S. Pat. Nos. 5,596,819 and 5,437,110 (Goldston, et al.) disclose an adjustable shoe heel spring and stabilizer device for a running shoe including a spring mechanism disposed in the real sole of the shoe and including a cantilevered spring member and an adjustable fulcrum therefor. U.S. Pat. No. 4,492,046 (Kosova) discloses a running shoe which includes a spring wire located in a longitudinal slot in the shoe sole extending from the back edge thereof into the arch region. U.S. Pat. No. 2,447,603 (Snyder) discloses a U-shaped spring plate disposed between the heel of the shoe and overlying a rear portion of the shoe sole. Other U.S. Pat. Nos. of possible interest include: 2,444,865 (Warrington); 3,822,490 (Murawski); 4,592,153 (Jacinta); 5,343,636 (Sabol); 5,435,079 (Gallegos); 5,502,901 (Brown); 5,511,324 (Smith); 5,517,769 (Zhao); and 5,544,431 (Dixon).

In accordance with the invention, an improved shoe or shoe construction is provided which affords important advantages including, inter alia, cushioning the initial impact on the heel area, facilitating the shifting of the weight of a wearer from the heel area to the ball of the foot, and enhancing lift-off from the ground in the toe and ball area of the foot.

Accordingly to a preferred embodiment of the invention, a shoe construction is provided which comprises a base member including a raised front portion and a rearwardly extending sole portion, a flexible spring member disposed beneath the front portion of the base member, and a spring element including a front portion secured to the front portion disposed at an acute, non-zero angle with respect to the sole portion of the base member.

Preferably, the spring member comprises a substantially U-shaped spring having free ends affixed to the front portion of said base member at longitudinally spaced locations. Advantageously, the spring member further comprises a support shell which is secured to the front portion of said base member and in which the U-shaped spring is slidably received so as to permit removal of the spring. The support shell preferably includes first and second, longitudinally spaced, transversely extending rails against which the free ends of the U-shaped spring engage.

The base member preferably includes a curved portion located between the front portion and the sole portion for enhancing shifting of the weight of a wearer to the ball of the foot.

Advantageously, the sole portion of the base member is covered with a bottom sole. The bottom sole preferably comprises a perforated subsole having a plurality of spaced perforations therein and a porous underlayer covering the perforated subsole.

Preferably, the rear portion of the spring element is of greater flexibility than the front portion of the spring element. The rear portion of said spring element is advantageously comprised of a flexible graphite material which resists side to side torsion, and the front portion of the spring element is comprises of a graphite composite.

Advantageously, the acute angle between the flexible rear portion of said spring element and the sole portion of the base member is a value which lies between 20.degree. and 25.degree.. Preferably, the distal end of the rear portion of the spring element extends beyond the distal end of the rearwardly extending sole portion of the base member. In an advantageous implementation, the distal end of the rear portion of the spring element is located at a spacing of between 3 to 31/2 inches above the distal end of the rearwardly extending sole portion. Advantageously, a reinforcement member is disposed between the rear portion of the spring element and the rearwardly extending portion of the base member. A mounting means is preferably provided for removably mounting the reinforcement member on said rear portion of the spring element. The mounting means advantageously comprises a plurality of spaced support straps affixed to the rear portion of the spring element.

A cushion element is preferably disposed at the distal end of said rear portion of said spring element. A retaining strap is advantageously affixed to said sole portion of said base member and extending around said rear portion of said spring element. The retaining strap preferably includes an openable fastener. In addition, the shoe construction advantageously further comprises a retaining strap means affixed to the front portion of the base member and extending above the front portion of the spring element for receiving the front part of the foot of a wearer.

In accordance with a further aspect of the invention, a shoe construction is provided which comprises: a base or frame member including a raised front portion and an offset, rearwardly extending rear portion; a substantially U-shaped spring member, formed by a flat elongate spring element, which is affixed to the base member and is disposed beneath the front portion of the base member so as to extend longitudinally along the base member; and a foot receiving portion affixed to the base member.

In an important implementation of this aspect of the invention, the spring member has a rear end portion connected to the base member a front end portion in unconnected engagement with the front end portion of the base member. Preferably, the base member includes a downwardly projecting element and it is this element that is in unconnected engagement with the front end portion of the spring member. Advantageously, the base member includes a transitional portion between the front and rear portions thereof and the rear end portion of the spring member is embedded in the transitional portion.

Preferably, the shoe construction further comprises a spring element extending rearwardly from the base member above the rear portion of the base member. The spring element is advantageously disposed at an acute, non-zero angle with respect to the rear portion of the base member. In the embodiment wherein the base member includes a transitional portion between the front and rear portions thereof, the spring element preferably includes a first end embedded in this transitional portion.

Advantageously, the base member includes an upper surface including laterally spaced ridges and the foot receiving portion is affixed to the surface between the ridges. Preferably, the foot receiving portion is further affixed to spring element.

Preferably, an elastomeric sole is affixed to a bottom surface of the rear portion of said base member.

Other features and advantages of the invention will be set forth in, or apparent from, the following detailed description of preferred embodiments of the invention.

FIG. 1 is a side elevational view of a shoe construction in accordance with one preferred embodiment of the invention;

FIG. 2(a) to 2(e) are schematic side elevations of basic elements of the shoe construction of the invention illustrating sequential stages in landing and lifting of the shoe and showing the spring action provided thereby;

FIG. 3 is a side elevational view, partially broken away, of a shoe construction in accordance with a further preferred embodiment of the invention; and

FIG. 4 and 5 are a schematic side elevational view and bottom plan view, respectively, of a yet another embodiment of the invention.

Referring to FIG. 1, an exemplary embodiment of the shoe construction of the invention is shown. It should be understood that the illustrated embodiment is simply one example of a suitable overall shoe construction and the basic elements and principles of the invention, which are described more generally in connection with FIGS. 2(a) to 2(e), have general application. In this regard, the invention can, for example, be incorporated in a more conventional looking running shoe if desired.

In the illustrated embodiment, the shoe construction or shoe, which is generally denoted 10, includes a base member 12 including a raised, rigid front or sole support portion 12a, and an integral rigid subsole portion 12b stepped down from the front portion 12a and extending rearwardly therefrom. Base member 12 is preferably made of a rigid carbon graphite with an aluminum rod support, or of a like material and construction. A bowed, flexible spring member 14 is disposed beneath, and secured to, front portion 12a of base member 12. In a preferred embodiment, a small lip 12c (e.g., of 1/4" extent) is provided at the toe of base member 12. As illustrated, spring member 14 is disposed substantially directly under the ball of the foot and extends between the front of front portion 12a to a rear part of front portion 12a adjacent to a curved portion 12d of subsole 12b. The curvature of curved portion 12d is such as to enhance shifting of the weight of a wearer to the ball of the foot during running or walking as described in more detail below. The spring member 14 is preferably made of spring steel, flexible carbon graphite or the like.

In a preferred embodiment shown in FIG. 1, spring member 14 is of a two piece construction comprising a support shell or support housing 14a of an inverted, squared off U-shape and a spring 14b of a bowed or shallow generally U-shape. The ends of support shell 14a form two longitudinally spaced, transversely extending rails and support shell 14a is preferably constructed, e.g., of aluminum. As illustrated, the free ends of spring 14b engage against, but are not secured to, the respective rails formed by shell support 14a. With this construction, spring 14b can be slid in and out of shell 14a to enable replacement or substitution. Spring 14b preferably extends across the full width of the shoe 10 although the spring 14b can be more narrow if desired.

Secured to the front portion 12a of base member 12 is a sole spring element 16. Sole spring element 16 includes a front portion 16a which is preferably comprises of a non-flexible graphite composite, which is affixed to the front portion 16a which is preferably comprises of a non-flexible graphite composite, which is affixed to the front portion at 12a of base member 12 and on which rest the toes and ball of the feet of a wearer. Sole spring element 16 further includes a rear portion 16b which is preferably comprised of a flexible graphite material that resists side to side torsion, and which extends rearwardly of front portion 16a at an acute, non-zero angle with respect to subsole 12b. In a specific, non-limiting example, rear portion 16b forms an angle between bout 20.degree. and 25.degree., and preferably of about 22.degree., with subsole 12b, and the distal end of rear portion 16b is located about 3 to 3.5 inches above the plane of the ground. Although this height is advantageous, other heights can be used and, in general, a height of between about 1 and 6 inches could be workable. As illustrated, the distal end portion of sole spring element 16 extends a substantial distance beyond subsole 12b.

A supplementary, and optional, reinforcement member 18 is located between sole spring element 16 and subsole 12b, and, in the illustrated embodiment, is supported beneath sole spring element 16 by a series of spaced support straps or loops 20 secured to the undersurface of element 16. Alternatively, reinforcement member 18 can be received and held in a longitudinal groove or channel (not shown) formed in the bottom surface of rear portion 12b or can be affixed, at the front end thereof, to the front portion 12a of base member 12, e.g., by being secured in place in a slot or recess in front end portion 12a in a cantilever fashion. Reinforcement member 18 is preferably made of spring steel, flexible carbon graphite or the like. Reinforcement member 18 is preferably removable and can be replaced with a similar member having different characteristics, e.g., one providing additional spring force or one providing variable spring action because of the shape or construction thereof.

In the illustrated embodiment, an overlay, indicated 22 and made of rubber or the like, is provided on the upper surface of sole spring element 16, and a cushion element 24 of rubber or the like is provided at the distal end or heel portion of sole spring member 16.

In a preferred embodiment indicated schematically in FIG. 1, the subsole 12b, which is made of a rigid, light material, is of a perforated or grate-like construction including a plurality of perforations or holes 26a therein and is covered by a porous rubber bottom member or underlayer 26b. This enables water, and air, to rise up through the underlayer 26b into the holes 26a when the wearer is running on a wet surface to thereby prevent hydroplaning and increase the aerodynamics of the shoe. In the embodiment shown in FIG. 1, an open strap assembly 28, comprising a pair of transverse, U-shaped straps 28a interconnected by longitudinally extending connector straps 28b made of Nylon or the like, is affixed to the front portion 12a of base member 12 for gripping the front of the foot of a wearer. A further, single elongate strap 30, including a buckle fastener 30a, is adapted to fit around the wearer's foot just in front of the ankle.

The spring action provided by shoe 10 can perhaps be best appreciated by reference to FIGS. 2(a) to 2(e) wherein the basic elements of the shoe construction, viz., base member 12, spring member 14, sole spring element or member 16, and optional reinforcement member 18, are shown. FIG. 2(a) illustrates the relative positions of these members when the foot F of a wearer is lifted above the ground G and, in this instance, is about to land on the ground (the movement of the foot F being indicated by arrow A).

As shown in FIG. 2(b), as the shoe 10 hits the ground and the full weight of the wearer is received by, i.e., is brought to bear on, the shoe 10, the weight is first received by curved portion 12d and subsole 12b. Further, the rear portion 16b of spring element 16 begins bending backward to form an arch as indicated in FIG. 2(b). As a consequence, a whipping action is created as the weight of the wearer is shifted to the ball of the foot. Spring portion 16b thus accelerates lifting of the heel from the ground and propels the weight of the wearer forward to the ball of the foot where curved portion 12c acts as a pivot or fulcrum about which the weight is shifted to the front spring 14 and thus accelerates the movement of the foot in leaving the ground.

In general, spring 14 is not involved until the weight of a wearer shifts or rolls forward. Spring 14 is designed and constructed such that compression thereof begins only when more than one half of the body weight of the wearer is transferred thereto. As shown in FIG. 2(c), as the weight of wearer shifts forward to the ball of the foot as indicated by arrow F1, spring 14 is compressed and subsole 12b tips off of the ground G. As discussed above, as the force on the spring element 16 is released, the weight of the wearer is shifted to the front of the shoe 10 and the shoe 10 rolls forward on curved portion 12d and on spring member 14 until sufficient weight is transferred to cause spring member 14 to collapse or compress. At this point, both the heel of the foot and the subsole 12b are off of the ground because of the rolling or pivoting action around curved portion 12d.

Before the wearer begins to lift his or her foot, the weight of the wearer compresses spring 14. As the foot is lifted and weight is removed from spring 14, this spring provides a lifting force, indicated by arrow S2, on the ball area of the foot.

Finally, as shown in FIG. 2(e), all spring forces return to the initial states thereof, i.e., the states of FIG. 2a, when the shoe 10 is fully lifted from the ground G.

In a further alternative embodiment, a coil spring or another additional spring element (not shown) could be added in the space created within spring 14, i.e., between spring 14 and the lower surface of front portion 12a, to provide further spring force as needed.

Referring to FIG. 3, there is shown a shoe constructed in accordance with a further preferred embodiment of the invention. The shoe of this embodiment, which is generally 40, includes a base or frame member 42 including a raised, rigid front or sole support portion 42a and an integral rear or heel portion 42b which is stepped down from front portion 42a and extends rearwardly therefrom. Base member can be fabricated of a rigid plexiglass material or another suitable material.

A spring 44 in the shape of a shallow U is affixed at one end to heel portion 42b of base member 42. In a preferred embodiment, the other end of spring 44 is biased into contact with, but not affixed to, a downwardly projecting element 42c of front portion 42a. In other words, spring 44 is in unconnected engagement with projecting element 42c. With this construction, projecting element 42c rides along and cams against the facing portion of this end of spring 44 as the weight of the user is placed on the front portion 42a. This construction enables an increased range of movement of spring 44 and provides an increase in effective return spring force as compared with a spring construction such as that shown in FIG. 1 wherein both ends of the spring are fixed to the shoe. The size and length of spring 44 is increased as compared with spring 14 of FIG. 1 and, in this regard, spring 44 extends from the front of shoe 40 to a location near, or even rearwardly of, the middle of the shoe 40. Spring 44 can be constructed of reinforced carbon graphite or other suitable materials.

A sole member 46 preferably fabricated of rubber of the like is affixed to the flat bottom surface of rear portion 42b of base member 42. A further spring or spring element 48 is affixed at one thereof to base member 42 in the transitional area 42d between front portion 42a and rear portion 42b. Spring element 48 serves a function similar to spring element 16 of FIG. 1. Spring element 48 is formed of a simple flat member but can alternatively be shaped to conform to the shape of the bottom surface of the shoe upper 50. Spring element 48 can be constructed of carbon graphite or another suitable spring material.

Shoe upper 50 is affixed to the upper surface of spring element 48 and to the upper surface of front portion 42a of base member 42 between laterally spaced side ridges or rails, one of which denoted 42e, is shown in FIG. 3. Shoe upper 50 can, of course, take a number of different, more or less conventional, forms, and the overall appearance of the shoe 40 can also be made to be more like a conventional shoe.

Referring to FIGS. 4 and 5, there is shown, in a highly schematic manner, yet another embodiment of the invention. This embodiment is similar to that of FIG. 3 and like elements have been given the same reference numerals. In the embodiment of FIGS. 4 and 5, a further spring 51 is included which is similar to spring 44 but is nested within the latter in spaced relation thereto, as shown in FIG. 4. The forward end of spring 51 engages, but is not connected to, a downward projection 42f formed on base or frame member 42. Spring 51 includes a plurality of spikes or cleats 52 along the length thereof. Spring 44 includes a plurality of apertures of holes 54 therein which are arranged to register with spikes 52. Holes 54 are preferably covered by a thin elastomeric (e.g., rubber) membrane or covering 56 (see FIG. 4). As bottom spring 44 is compressed, spikes 52 protrude through apertures 54 to provide additional gripping. The spikes 52 deform, but do not penetrate through, membrane 56. The embodiment of FIGS. 4 and 5 provides variable spring action and, in this regard, both springs 44 and 51 provide lift.

It is noted that the retractable-extendable spike arrangement of FIGS. 4 and 5 could also be applied to a more conventional or traditional running shoe or like shoe. For example, a soft foam or rubber sole can be provided which compresses under the weight of the user (e.g., a runner) so that spikes or cleats are fully or partially exposed so as to grip the ground.

Although the present invention has been described relative to specific exemplary embodiments thereof, it will be understood by those skilled in the art that variations and modifications can be effected in these exemplary embodiments without departing from the scope and spirit of the invention.