Patent Description:
Shoes used for sports or the like are desired to follow the motion of foot portions of the wearer and firmly support the feet during walking, running, or exercising, for example, and also to reduce fatigue of the feet.

For example, Patent Literature <NUM> discloses a shoe sole that includes a curved portion extending between an anterior-most point disposed in a forefoot region and a posterior-most point disposed closer to a heel region than the anterior-most point. The curved portion has a constant radius of curvature in a region from the anterior-most point to a metatarsophalangeal point (MP point).

In Patent Literature <NUM>, the shoe sole in the forefoot region is curved to reduce the length of the lever arm about the ankle, thereby reducing the strain at the ankle joint; however, dissipation of energy caused by the motion of the ankle joint itself is not considered. With regard to the dissipation of energy caused by the motion of the ankle joint itself, the inventors have obtained the following findings.

The range of motion of the ankle joint angle in the sagittal plane varies according to the relative height positions of the heel and the toe. For example, in a situation where a person walks or runs forward, when the heights of the heel and the toe are almost the same, the motion of the ankle joint accompanying the forward shift of the center of gravity becomes larger before rotational motion of the foot starts, so that the strain due to the dissipation of energy caused by the motion of the ankle joint itself is increased. In the shoe sole described in Patent Literature <NUM>, the thickness of the shoe sole in the heel portion, i.e., the height of the heel portion, is almost the same as the height of the toe, as illustrated in <FIG> of Patent Literature <NUM> for example, and the ankle joint angle in the sagittal plane is not considered.

The present invention has been made in view of such an issue, and a purpose thereof is to provide a shoe sole and a shoe that can restrain the motion of the ankle joint and reduce the energy generated at the ankle joint.

The invention is defined by the appended independent claim <NUM>. Additional embodiments are defined in the dependent claims. An aspect of the present disclosure relates to a shoe sole. The shoe sole includes: a bottom part that includes a rear bottom surface part formed to extend from a rearfoot portion to a midfoot portion and to be, when the shoe sole is placed on a virtual surface as a flat surface, in contact with the virtual surface and that also includes a toe portion of which a height from the virtual surface is set to <NUM>% or greater and <NUM>% or less with respect to a thickness dimension in the rear bottom surface part; and a deformation restraining part (high stiffness part) that is disposed in an edge part on a medial side and a lateral side of the bottom part and extends from a forefoot portion to the midfoot portion along the bottom part and that has higher hardness than the bottom part.

A shoe sole of another aspect of the present disclosure includes: a bottom part that includes a rear bottom surface part formed to extend from a rearfoot portion to a midfoot portion and to be, when the shoe sole is placed on a virtual surface as a flat surface, in contact with the virtual surface and that also includes a front bottom surface part formed to continue to a front part of the rear bottom surface part and also curvedly extend to a toe portion such as to be spaced away from the virtual surface; and a deformation restraining part that is disposed in an edge part on a medial side and a lateral side of the bottom part and extends from a forefoot portion to the midfoot portion along the bottom part and that has higher rigidity than the bottom part. In the shoe sole, the rigidity against bending deformation in a vertical direction of the whole shoe sole is in the range from <NUM> N/mm to <NUM> N/mm inclusive.

A shoe sole of yet another aspect of the present disclosure includes: a bottom part including a bottom surface part that includes a rear bottom surface part formed to extend from a rearfoot portion to a midfoot portion and to be, when the shoe sole is placed on a virtual surface as a flat surface, in contact with the virtual surface and that also includes a front bottom surface part formed to continue to a front part of the rear bottom surface part and also curvedly extend to a toe portion such as to be spaced away from the virtual surface; and a deformation restraining part that is disposed in an edge part on a medial side and a lateral side of the bottom part and extends from a forefoot portion to the midfoot portion along the bottom part and that has higher hardness than the bottom part. In the shoe sole, the bottom part further includes an upper surface part that includes a first upper surface part constituted by a surface formed to extend from the rearfoot portion to the midfoot portion and formed to be parallel with the virtual surface or to extend downward from a rear part toward a front side in an unloading state and that also includes a second upper surface part constituted by a surface formed to continue to a front end of the first upper surface part and extend upward toward the front side to reach the toe portion. Also, in the shoe sole, a region facing an MP joint part of a foot is provided in the front bottom surface part in the bottom surface part and in the second upper surface part in the upper surface part.

A further aspect of the present disclosure relates to a shoe. The shoe includes a shoe sole described above, and an upper disposed on the shoe sole.

Optional combinations of the aforementioned constituting elements, and implementation of the present disclosure, including the constituting elements and expressions, in the form of methods or apparatuses may also be practiced as additional modes of the present disclosure.

The present invention can restrain the motion of the ankle joint and reduce the energy generated at the ankle joint.

Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which:.

In the following, the present invention will be described based on preferred embodiments with reference to <FIG>. Like reference characters denote like or corresponding constituting elements and members in each drawing, and repetitive description will be omitted as appropriate. Also, the dimensions of a member may be appropriately enlarged or reduced in each drawing in order to facilitate understanding. Further, in each drawing, part of members less relevant in describing embodiments may be omitted.

<FIG> is an exploded perspective view that illustrates an external view of a shoe <NUM> according to the first embodiment. The shoe <NUM> includes an upper <NUM> and a shoe sole <NUM>. The upper <NUM> is bonded to or sewed onto a circumferential edge part of the shoe sole <NUM> to cover the upper side of a foot. The shoe sole <NUM> includes an outer sole <NUM> (see <FIG>), a bottom part <NUM>, and a deformation restraining part <NUM>, for example, and is configured by laminating the deformation restraining part <NUM> and the bottom part <NUM> on the outer sole <NUM> and further laminating an insole or the like thereon, which is not illustrated.

<FIG> is a schematic diagram in which a skeleton model of a human foot is superimposed upon a plan view of the shoe sole <NUM>. A human foot is mainly constituted by cuneiform bones Ba, a cuboid bone Bb, a navicular bone Bc, a talus Bd, a calcaneus Be, metatarsal bones Bf, and phalanges Bg. Joints of a foot include MP joints Ja, Lisfranc joints Jb, and a Chopart's joint Jc. The Chopart's joint Jc includes a calcaneocuboid joint Jc1 formed by the cuboid bone Bb and the calcaneus Be, and a talocalcaneonavicular joint Jc2 formed by the navicular bone Bc and the talus Bd.

In the present invention, a center line N of a foot is represented by a straight line connecting a midpoint N3 between the center N1 of the thenar eminence and the center N2 of the hypothenar eminence, and the center N4 of the heel. For example, a longitudinal direction Y is in parallel with the center line N, and a width direction X is perpendicular to the center line N. A line P represents a straight line that extends along a width direction X, which is a direction perpendicular to the center line N, and that is assumed to pass through the heel-side end of the MP joints Ja. Also, a line Q represents a straight line that extends along a width direction X and that is assumed to pass through the toe-side end of the Chopart's joint Jc of the wearer. Hereinafter, a region from the line P to the toe is referred to as a forefoot portion, a region from the line P to the line Q is referred to as a midfoot portion, and a region from the line Q to the heel is referred to as a rearfoot portion. With regard to the relationship between the lines P, Q and the shoe <NUM>, the line P is positioned within a range from <NUM>% to <NUM>% of the entire length M of the shoe <NUM> from the rear end on the heel side in a direction along the center line N, for example. More preferably, the line P is positioned within a range from <NUM>% to <NUM>% from the rear end. Also, the line Q is positioned within a range from <NUM>% to <NUM>% of the entire length M of the shoe <NUM> from the rear end on the heel side in a direction of a center line N. More preferably, the line Q is positioned within a range from <NUM>% to <NUM>% from the rear end.

<FIG> is an exploded perspective view of the shoe sole <NUM>. The outer sole <NUM> includes a bottom surface portion, which comes into contact with a road surface, formed along the entire foot length in a longitudinal direction Y. The toe side is positioned higher than the heel side so that the motion of a foot from the landing to pushing off can be smoothly performed. The outer sole <NUM> is formed of a rubber material or the like, so as to absorb unevenness of the road surface and have abrasion resistance and durability.

The outer sole <NUM> includes a medial side cover portion <NUM> that extends from the toe to the midfoot portion on the medial side, a lateral side cover portion <NUM> that extends from the toe to the midfoot portion on the lateral side, and a heel cover portion <NUM>. The medial side cover portion <NUM> and the lateral side cover portion <NUM> of the outer sole <NUM> are continuous at the toe and the midfoot portion and also extend from the midfoot portion to the rearfoot portion. The heel cover portion <NUM> is formed in a U-shape that extends from the rear end to the medial side and the lateral side. The heel cover portion <NUM> may be continuous with the medial side cover portion <NUM> and the lateral side cover portion <NUM> or may be separated from the medial side cover portion <NUM> and the lateral side cover portion <NUM> with a slight gap in between, as illustrated in <FIG>.

The bottom part <NUM> is disposed on the outer sole <NUM> and formed along the entire foot length in a longitudinal direction Y. The toe side of the bottom part <NUM> is positioned higher than the heel side thereof so that the motion of a foot from the landing to pushing off can be smoothly performed. The bottom part <NUM> includes a recess <NUM> in an edge part on each of the medial side and the lateral side. The recesses <NUM> are formed such as to hole the lower surface side and both the left and right side surfaces of the bottom part <NUM> and extend from the forefoot portion to the rearfoot portion.

The deformation restraining part <NUM> is constituted by a medial deformation restraining part <NUM> and a lateral deformation restraining part <NUM>, which are stick-shaped. The medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> extend respectively on the medial side and the lateral side of the bottom part <NUM> from the forefoot portion to the rearfoot portion and are fitted and bonded to the recesses <NUM> provided in the edge part of the bottom part <NUM>. The deformation restraining part <NUM> is provided closer to the vertically lower side of the bottom part <NUM> and is provided between the outer sole <NUM> and the bottom part <NUM>. The hardness of the deformation restraining part <NUM> is higher than that of the outer sole <NUM> and the bottom part <NUM>. In addition, the rigidity against the bending deformation in a vertical direction of the deformation restraining part <NUM> is also higher than that of the outer sole <NUM> and the bottom part <NUM>. The rigidity against the bending deformation of the whole shoe sole <NUM> may be in the range from <NUM> N/mm to <NUM> N/mm inclusive, for example. It is assumed here that the rigidity against the bending deformation of the whole shoe sole <NUM> represents rigidity exhibited when the toe end of the shoe sole <NUM> is pressed in a vertical direction while the heel end of the shoe sole <NUM> is fixed.

<FIG> is a bottom view of the shoe sole <NUM>, and <FIG> is a sectional view taken along line A-A shown in <FIG>. The medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> each have a rectangular cross section and are bonded to the left and right side surfaces of the bottom part <NUM> at inner side surfaces 31a and 32a. The lower ends of the inner side surfaces 31a and 32a are covered with the medial side cover portion <NUM> and the lateral side cover portion <NUM> of the outer sole <NUM>, thereby preventing peeling off of the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> from the bottom part <NUM>. The deformation restraining part <NUM> may be formed outside a region where the wearer's foot is in contact with the bottom part <NUM>.

<FIG> are sectional views of shoe soles <NUM> according to modifications, taken along line A-A shown in <FIG>. The medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> shown in <FIG> each have a triangular cross section, and the inner side surfaces 31a and 32a are inclined such as to extend inward in a lateral direction (width direction X) toward the lower side. The lower ends of the inner side surfaces 31a and 32a are covered with the medial side cover portion <NUM> and the lateral side cover portion <NUM> of the outer sole <NUM>, thereby preventing peeling off of the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> from the bottom part <NUM>. Also, since the inner side surfaces 31a and 32a of the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> are inclined such as to extend inward in a lateral direction toward the lower side, the feeling of hardness at a portion with which the foot comes into contact can be reduced.

The medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> shown in <FIG> are each formed to have an L-shaped cross section. The inner side surfaces 31a and 32a are each formed in a stair-like pattern with a stepped portion. The lower ends of the inner side surfaces 31a and 32a are covered with the medial side cover portion <NUM> and the lateral side cover portion <NUM> of the outer sole <NUM>, thereby preventing peeling off of the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> from the bottom part <NUM>.

<FIG> is a side view of a lateral side of the shoe sole <NUM>, and <FIG> is a vertical sectional view of the shoe sole, which includes the center line N shown in <FIG>. When the shoe sole <NUM> is placed on a flat virtual surface S, such as a ground surface, a rear bottom surface part <NUM> extending from the midfoot portion to the rearfoot portion is in contact with the virtual surface S. The rear bottom surface part <NUM> may be in contact with the virtual surface S entirely in a longitudinal direction or may be partially spaced away from the virtual surface S, such as in a rear part of the heel portion. To improve the stability in a region from the heel portion to the midfoot portion at the time of landing, the portion to be in surface-contact of the rear bottom surface part <NUM> in the heel portion and the midfoot portion may preferably be provided in a range of <NUM>% or greater of the entire length M of the shoe sole <NUM>, and more preferably be provided in a range of <NUM>% or greater thereof. With regard to the surface-contact, when fine asperities are provided on the rear bottom surface part <NUM>, a surface that passes through the lowermost surfaces of the asperities may be regarded as a virtual rear bottom surface part <NUM>.

A front bottom surface part <NUM> is provided to continue to the front part of the rear bottom surface part <NUM> and also extend to a toe portion <NUM> such as to be spaced away from the virtual surface S. The front bottom surface part <NUM> extends upward toward the front side and reaches the toe portion <NUM>. The front bottom surface part <NUM> is formed only by a curved surface and a linear surface and does not include a portion extending downward toward the front side. The boundary between the rear bottom surface part <NUM> and the front bottom surface part <NUM> is positioned between the position of <NUM>% of the entire length M of the shoe sole <NUM> from the front end and a point P0 corresponding to an MP joint (the entire length M is assumed to be identical with the entire length of the shoe <NUM>, and the same applies hereinafter). The rear bottom surface part <NUM> and the front bottom surface part <NUM> form a bottom surface part <NUM>. The point P0 corresponding to an MP joint may be a position corresponding to the thenar eminence on the upper surface of the bottom part <NUM>, as shown in <FIG>, or may be a position corresponding to the hypothenar eminence among the MP joints. In other words, P0 may be positioned within a range from <NUM>% to <NUM>% of the entire length M of the shoe sole <NUM> from the rear end.

A height L3 of the toe portion <NUM> is defined as a height from the virtual surface to a point P3 at which an edge portion 26a, which is joined with the upper <NUM> in the upper surface of the bottom part <NUM> (an inner-side surface of the shoe <NUM>), extends upward, as illustrated in <FIG>. The height L3 of the toe portion <NUM> may also be defined as a height from the virtual surface to a point P4, which is the tip of the outer shape of the toe portion <NUM>. In the following description, the height from the virtual surface to the point P3 is used as the height L3 of the toe portion <NUM>.

The thickness of the rear bottom surface part <NUM> side of the shoe sole <NUM> is considered based on one of a thickness L1 of the shoe sole <NUM> at a point P1 in the heel portion and a thickness L2 of the shoe sole <NUM> at a point P2 in the midfoot portion. The height L3 of the toe portion <NUM> is set to <NUM>% or greater and <NUM>% or less of the thickness L1 of the shoe sole <NUM> at the point P1 in the heel portion. The height L3 of the toe portion <NUM> may preferably be set to <NUM>% or greater of the thickness L1 of the shoe sole <NUM> at the point P1 in the heel portion. The height L3 of the toe portion <NUM> is also set to <NUM>% or greater and <NUM>% or less of the thickness L2 of the shoe sole <NUM> at the point P2 in the midfoot portion. The height L3 of the toe portion <NUM> may preferably be set to <NUM>% or greater of the thickness L2 of the shoe sole <NUM> at the point P2 in the midfoot portion. The position of the point P2 in the midfoot portion may be defined as a position in the thickest part within a range from about <NUM>% to <NUM>% of the entire length M of the shoe sole <NUM> from the rear end. When the height L3 of the toe portion <NUM> is defined as the height at the point P4, the height L3 is set to <NUM>% or greater and <NUM>% or less of the thickness L2 of the shoe sole <NUM> at the point P2 in the midfoot portion and may preferably be set to <NUM>% or greater of the thickness L2 of the shoe sole <NUM> at the point P2 in the midfoot portion.

The position of the point P1 in the heel portion may be defined as a position in the thickest part in the heel portion (a range from <NUM>% to <NUM>% of the entire length M of the shoe sole <NUM> from the rear end), and the thickness dimension of the shoe sole <NUM> at the point P1 may be set to <NUM> or greater, for example. The rigidity against the bending deformation in an extension direction of the shoe sole <NUM> corresponding to an MP joint part, obtained by three-point bend testing, may be <NUM> N/mm or greater, for example. In the three-point bend testing, an <NUM>-centimeter length in a longitudinal direction that crosses the MP joint part is supported at the both ends, a middle part between the both ends is pressed downward to obtain the relationship between the displacement and the load, and the slope of the displacement-load curve in a range of the displacement of <NUM> to <NUM> is obtained. Also, the difference between the thickness of the shoe sole <NUM> in the heel portion in an unloading state where a foot is not placed on the shoe sole <NUM> and the thickness of the shoe sole <NUM> at a position corresponding to the MP joint part may be set to <NUM> or less, for example.

<FIG> are schematic diagrams used to describe an upper surface part <NUM> of the shoe sole <NUM>. Each of <FIG> illustrates a sectional view similar to that in <FIG>. A first upper surface part <NUM> is formed to extend from the rearfoot portion to the midfoot portion and corresponds to a surface included in predetermined parallel conditions with respect to the virtual surface S in an unloading state. The surface included in predetermined parallel conditions means a surface positioned between a virtual plane SU1 and a virtual plane SU2. The virtual plane SU1 is the highest surface within a region that includes a front end of the first upper surface part <NUM> (front part), which will be described later, and a position of <NUM>% of the entire length M of the shoe sole <NUM> from the rear end (rear part), and the virtual plane SU2 is the lowest surface in the region. The surface included in predetermined parallel conditions is also located within a region where the height difference between SU1 and SU2 is <NUM> or less and formed to be parallel with the virtual surface S or to incline downward from the rear part toward the front part. <FIG> illustrates the case where the first upper surface part <NUM> is parallel with the virtual surface S. <FIG> illustrates the first upper surface part <NUM> formed to incline downward from the rear part to the front part with a height reduction amount of <NUM>. For less incongruity on the bottom of a foot, the first upper surface part <NUM> may be suitably flat with fewer asperities; however, the first upper surface part <NUM> may have some asperities, have a height difference in a width direction, or have a twist, for example.

A second upper surface part <NUM> continues to the front end of the first upper surface part <NUM> and extends upward toward the front side to reach the toe portion <NUM>. The second upper surface part <NUM> is formed only by a curved surface and a linear surface extending upward toward the front side and does not include a portion extending downward toward the front side. As illustrated in <FIG>, the second upper surface part <NUM> is curved to be recessed with respect to the upper side. The boundary (front end) between the first upper surface part <NUM> and the second upper surface part <NUM> may be positioned within a range from <NUM>% to <NUM>% of the entire length M of the shoe sole <NUM> from the front end of the shoe sole <NUM>, for example.

The upper surface of the bottom part <NUM> in the shoe sole <NUM> has been described with reference to <FIG>. However, when an inner sole, omitted in the drawings, is provided on the bottom part <NUM>, the first upper surface part <NUM> and the second upper surface part <NUM> as described above may be defined in the upper surface of the inner sole.

For the outer sole <NUM>, rubber, rubber foam, thermoplastic polyurethane (TPU), a thermoplastic elastomer, and a thermosetting elastomer may be used, for example. The bottom part <NUM> may be formed of resin foam, for example. As a resin, a polyolefin resin, ethylene-vinyl acetate copolymer (EVA), or a styrene elastomer may be used, for example, and the resin may contain other arbitrary components, such as fiber, as appropriate. For the deformation restraining part <NUM>, resin foam using a polyolefin resin, EVA, or a styrene elastomer may be used, for example, and the resin foam may contain other arbitrary components, such as cellulose nanofiber or other fiber, as appropriate.

The hardness of the outer sole <NUM> may be set to HA70, for example. Also, the hardness of the bottom part <NUM> may be set to HC55, and the hardness of the deformation restraining part <NUM> may be set to HC67, for example.

There will now be described the functions of the shoe <NUM>. <FIG> is a chart used to describe rotational motion of the ankle joint in a longitudinal direction. A column A in <FIG> shows a case where the bottom surface of the shoe sole <NUM> is almost flat, and the rotational motion of the ankle joint in a longitudinal direction is large. In the column A, the body weight is shifted forward after the landing and the ankle joint is bent forward, so that an angle α(α2) at the ankle joint becomes smaller. Such rotational motion of the ankle joint causes stretch motion of muscles of the foot. Thereafter, the angle α(α3) at the ankle joint inversely becomes larger until the pushing off.

Meanwhile, a column B in <FIG> shows a case where the shoe sole <NUM> includes the front bottom surface part <NUM> described above, and the rotational motion of the ankle joint in a longitudinal direction is small. In the column B, when the body weight is shifted forward after the landing, the shoe sole <NUM> is rotated such that the front bottom surface part <NUM> comes into contact with a road surface. Accordingly, the forward rotational motion is restrained, so that the change of the angle α(α2) at the ankle joint is small. Thereafter, the change of the angle α(α3) at the ankle joint remains small until the pushing off.

<FIG> is a graph as an example that shows energy consumption in the ankle joint. In <FIG>, the horizontal axis represents time, and the vertical axis represents energy consumption in the ankle joint, and the energy consumption is compared between the cases of the columns A and B in <FIG>. Although energy consumption is generally a positive value, the case where muscles contract is indicated in the positive direction, and the case where muscles stretch is indicated in the negative direction, for the sake of convenience.

The energy consumption at the time of landing is greater in the case of the shoe sole <NUM> in the column A, compared to the case of the shoe sole <NUM> in the column B. The energy consumption at the time of landing is reduced mainly by the cushion member <NUM> provided in the heel portion of the shoe sole <NUM>. Until the pushing off after the landing, the rotational motion of the angle α at the ankle joint can be made smaller in the case of the column B compared to the case of the column A, as described with reference to <FIG>. Accordingly, the energy consumption becomes smaller in the case of the column B.

With the rear bottom surface part <NUM> provided, the stability at the time of landing of a foot can be ensured in the shoe sole <NUM> of the shoe <NUM>. Also, since the toe portion <NUM> is positioned higher than the rear bottom surface part <NUM>, the rotational motion of the ankle joint in a longitudinal direction during walking and running is reduced and the energy consumption is also reduced, so that strain at the foot can be reduced. With reference to <FIG>, by setting the height L3 of the toe portion <NUM> from the virtual surface S to <NUM>% or greater with respect to the thickness dimension L1 of the rear bottom surface part <NUM> in the heel portion, the effect of reducing the energy consumption can be achieved. Also, the height L3 of the toe portion <NUM> from the virtual surface S may preferably be set to <NUM>% or greater of the thickness dimension L1 of the rear bottom surface part <NUM> in the heel portion. Also, by setting the height L3 of the toe portion <NUM> from the virtual surface S to <NUM>% or less with respect to the thickness dimension L1 in the heel portion, the bending angle at the MP joint part of the foot can be maintained within a certain range.

By setting the height L3 of the toe portion <NUM> from the virtual surface S based on the thickness dimension L1 in the heel portion, after the landing of the heel portion, the strain at the ankle joint placed during the rotational motion of the shoe sole <NUM> toward the toe portion can be reduced. Also, the height L3 of the toe portion <NUM> from the virtual surface S may be set to <NUM>% or greater and <NUM>% or less with respect to the thickness dimension L2 in the midfoot portion. In this case, it is considered that, at least after the landing of the midfoot portion, the strain at the ankle joint placed during the rotational motion toward the toe portion <NUM> in the shoe sole <NUM> can be reduced. Also, the height L3 of the toe portion <NUM> from the virtual surface S may preferably be set to <NUM>% or greater of the thickness dimension L2 in the midfoot portion.

With reference to <FIG>, the first upper surface part <NUM> is formed as a surface included in predetermined parallel conditions, as described previously. The second upper surface part <NUM> is formed to continue to the front end of the first upper surface part <NUM> and extend upward toward the front side. By maintaining the downward inclination of the first upper surface part <NUM> toward the front side within a certain range, the upward inclination of the second upper surface part <NUM> toward the front side can be made gentle. Making the upward inclination of the second upper surface part <NUM> toward the front side gentle can restrain increase of the upward bending angle at the MP joint part of the foot.

Since the rear bottom surface part <NUM> includes a portion to be in surface-contact with the virtual surface S in the rearfoot portion and the midfoot portion, the stability at the time of landing of the rear bottom surface part <NUM> can be increased. Also, since the front bottom surface part <NUM> continues to the front part of the rear bottom surface part <NUM> and also curvedly extends to the toe portion <NUM>, the rotational motion of the foot can be smoothly performed. In the front bottom surface part <NUM>, by making a radius of curvature R1 in the rear part continuing to the rear bottom surface part smaller than a radius of curvature R2 in the toe portion, the rotational motion of the shoe sole <NUM> after the landing of the midfoot portion can be made to function more easily. The radius of curvature R1 smaller than the radius of curvature R2 may be positioned along the MP joint part from the medial side to the lateral side, for example. When R1 is set to <NUM>% or less of R2, the effect of smoother rotational motion can be obtained.

Also, in the region of the front bottom surface part <NUM>, the point P0 facing the MP joint part of a foot is included. Accordingly, while the rotational motion of the shoe sole <NUM> proceeds after the landing of the midfoot portion until the landing of the toe portion <NUM>, the motion of the MP joint part of the foot is made smaller. With such smaller motion of the MP joint part of the foot, energy consumption in the MP joint part is reduced, and the strain caused by stretching and contraction in the MP joint part can be reduced.

The deformation restraining part <NUM> has higher hardness than the bottom part <NUM> and functions to restrain deformation of the shoe sole <NUM> or the foot, thereby maintaining a constant foot shape more easily. Since the deformation restraining part <NUM> is constituted by the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM>, twisting deformation around a longitudinal axis of the shoe sole <NUM> can be allowed. For example, if the ground on which the foot has landed includes undulations on the medial side and the lateral side due to inclination or the like, the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> can be independently deformed, so that the shoe sole <NUM> as a whole gets twisted and deformed around the longitudinal axis and hence can follow the undulations of the ground.

The bottom part <NUM> has lower hardness than the deformation restraining part <NUM> and functions as a deformation allowance part in the shoe sole <NUM> for absorbing impact at the time of landing or unevenness of the road surface. Also, the bottom part <NUM> is provided higher than the deformation restraining part <NUM> and is in contact with the wearer's foot. Accordingly, the lower hardness of the bottom part <NUM> can reduce the load on the foot due to impact or the like and the pushing up of the foot due to unevenness of the road surface. Also, when the deformation restraining part <NUM> is formed outside the region where the wearer's foot is in contact with the bottom part <NUM>, the feeling of hardness on the medial side and the lateral side of the foot can be prevented.

The rigidity against the bending deformation of a material of a plate shape at the time of bending the material is generally determined based on the Young's modulus and the second moment of area of the material. If the material physical properties, including hardness, are the same and the width is also the same, the rigidity against the bending deformation is proportional to the cube of the material thickness. Accordingly, when the shoe sole <NUM> is made thinner, the material physical properties need to be supplemented by insertion of a high-strength member, such as a carbon fiber reinforced plastic, or increase of hardness of the outer sole <NUM>, for example. The outer sole <NUM> also functions as a deformation restraining part.

When the toe portion <NUM> of the shoe sole <NUM> extends upward such that the height of the toe portion <NUM> is <NUM>% or greater of the thickness dimension L1 of the shoe sole <NUM> in the heel portion or the thickness dimension L2 of the shoe sole <NUM> in the midfoot portion (at a position of <NUM>% of the entire length M from the rear end, for example) and when the rigidity against the bending deformation in a longer axis direction in the forefoot portion of the shoe sole <NUM> (the rigidity at a position corresponding to the MP joint part) is three or more times larger than the rigidity of general running shoes (<NUM> N/mm as a reference value), the deformation of the shoe sole <NUM> is restrained, and the effect of reducing the strain at the ankle joint can achieved.

When the height of the toe portion <NUM> extending upward is low, it is ineffective even though the shoe sole <NUM> is hard. Since the change of the angle at the ankle joint can be made small and the angular velocity can be reduced while the foot is in contact with the ground during walking and running, the workload of the ankle joint is reduced, thereby enabling walking and running with less effort.

<FIG> are bottom views in which the outer sole of the shoe sole <NUM> according to the second embodiment is omitted. In the shoe sole <NUM> shown in <FIG>, the longitudinal length of the medial deformation restraining part <NUM> of the deformation restraining part <NUM> is longer than that of the lateral deformation restraining part <NUM>. The medial deformation restraining part <NUM> extends from the forefoot portion to about the middle in a longitudinal direction of the rearfoot portion, and the lateral deformation restraining part <NUM> extends from the forefoot portion to the rear end of the midfoot portion or to the front end of the rearfoot portion. This can ease the restraint on the bending deformation in a vertical direction of the shoe sole <NUM> on the lateral side.

In the shoe sole <NUM> shown in <FIG>, the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> of the deformation restraining part <NUM> have similar longitudinal lengths and each extend from the forefoot portion to the rear end of the midfoot portion or to the front end of the rearfoot portion. This can ease the restraint on the bending deformation in a vertical direction of the shoe sole <NUM> on the medial side and the lateral side.

In the shoe sole <NUM> shown in <FIG>, the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> of the deformation restraining part <NUM> have similar longitudinal lengths and each extend from the forefoot portion to about the middle in a longitudinal direction of the rearfoot portion. Also, the deformation restraining part <NUM> includes a connection part <NUM> that connects a position around the middle in a longitudinal direction of the medial deformation restraining part <NUM> and a position around the rear end of the lateral deformation restraining part <NUM>. With the connection part <NUM> provided, the positional relationship between the medial side and the lateral side of the deformation restraining part <NUM> can be maintained, so that the durability can be improved.

<FIG> is a perspective view that illustrates an external view of the shoe sole <NUM> according to the third embodiment, and <FIG> is an exploded perspective view of the shoe sole <NUM>. <FIG> is a sectional view of the shoe sole <NUM> at a cross section equivalent to that shown in <FIG>. As is the case in the first and second embodiments, the shoe sole <NUM> according to the third embodiment also includes the outer sole <NUM>, the bottom part <NUM>, and the deformation restraining part <NUM>; however, the bottom part <NUM> is divided into an upper bottom part 20a and a lower bottom part 20b. Also, the deformation restraining part <NUM> includes a connection part <NUM> that connects the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> on the toe side.

In the bottom part <NUM>, a recess <NUM> is formed on the medial side, the lateral side, and the toe part of the lower bottom part 20b, and the deformation restraining part <NUM> is fitted into the recess <NUM>. The deformation restraining part <NUM> is bonded such as to be sandwiched between the upper bottom part 20a and the lower bottom part 20b. Also, the lower surface of the upper bottom part 20a is bonded to the upper surface of the lower bottom part 20b. Although the upper bottom part 20a and the lower bottom part 20b may be formed by integral molding, if the shape of the recess <NUM> into which the deformation restraining part <NUM> is fitted is made complex thereby, the manufacturability can be improved by separately forming the upper bottom part 20a and the lower bottom part 20b, as shown in <FIG>.

Also, the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM> of the deformation restraining part <NUM> are connected by the connection part <NUM> on the toe side, which facilitates the handling of the shoe sole <NUM> at the time of assembly and hence facilitates the assembly.

As illustrated in <FIG>, the deformation restraining part <NUM> is positioned closer to the vertically upper side of the lower bottom part 20b, and the lower surface side of the deformation restraining part <NUM> is covered with the lower bottom part 20b. Accordingly, the deformation restraining part <NUM> is not exposed to the lower surface side of the shoe sole <NUM>, so that the peeling off of the bonded part of the deformation restraining part <NUM> can be prevented. Also, when viewed along a vertical direction, the deformation restraining part <NUM> is disposed around the middle of the bottom part <NUM> including the upper bottom part 20a and the lower bottom part 20b; however, by reducing the thickness of the upper bottom part 20a, the positional relationship can be made such that the deformation restraining part <NUM> is disposed closer to the vertically upper side of the bottom part <NUM>.

As is the case in the first embodiment, the shoe sole <NUM> is formed such that the toe side is positioned higher than the heel side. Accordingly, when the wearer of the shoe <NUM> walks or runs, energy consumption at the ankle joint can be reduced, thereby enabling walking and running with less effort.

There will now be described the features of the shoe sole <NUM> and the shoe <NUM> according to the embodiments and the modifications.

The shoe sole <NUM> includes the bottom part <NUM> and the deformation restraining part <NUM>. The bottom part <NUM> includes: the rear bottom surface part <NUM> formed to extend from the rearfoot portion to the midfoot portion and to be, when the shoe sole is placed on the virtual surface S as a flat surface, in contact with the virtual surface S; and the toe portion <NUM> of which the height from the virtual surface S is set to <NUM>% or greater and <NUM>% or less with respect to the thickness dimension in the rear bottom surface part <NUM>. The deformation restraining part <NUM> is disposed in an edge part on the medial side and the lateral side of the bottom part <NUM> and extends from the forefoot portion to the midfoot portion along the bottom part <NUM>. Also, the deformation restraining part <NUM> has higher hardness than the bottom part <NUM>. Accordingly, the shoe sole <NUM> can ensure stability of landing of the rear bottom surface part <NUM> and also reducing the strain at the ankle joint during forward walking and running.

The shoe sole <NUM> includes the bottom part <NUM> and the deformation restraining part <NUM>. The bottom part <NUM> includes: the rear bottom surface part <NUM> formed to extend from the rearfoot portion to the midfoot portion and to be, when the shoe sole is placed on the virtual surface S as a flat surface, in contact with the virtual surface S; and the front bottom surface part <NUM> formed to continue to a front part of the rear bottom surface part <NUM> and also curvedly extend to the toe portion <NUM> such as to be spaced away from the virtual surface S. The deformation restraining part <NUM> is disposed in an edge part on the medial side and the lateral side of the bottom part <NUM> and extends from the forefoot portion to the midfoot portion along the bottom part <NUM>. Also, the deformation restraining part <NUM> has higher rigidity than the bottom part <NUM>. The rigidity against the bending deformation in a vertical direction of the whole shoe sole <NUM> is in the range from <NUM> N/mm to <NUM> N/mm inclusive. Accordingly, the shoe sole <NUM> can ensure stability of landing of the rear bottom surface part <NUM> and also reduce the strain at the ankle joint during forward walking and running. The rigidity against the bending deformation of the deformation restraining part <NUM> may preferably be in the range from <NUM> times to <NUM> times, inclusive, the rigidity against the bending deformation of other regions, such as a center part of the shoe sole <NUM> sandwiched between the medial deformation restraining part <NUM> and the lateral deformation restraining part <NUM>. If the rigidity against the bending deformation of the deformation restraining part <NUM> is low, the shoe sole <NUM> will be easily deformed. However, if the rigidity against the bending deformation of the deformation restraining part <NUM> is excessively high, a large shear force may be applied to the boundary regions with other portions, and hence, the shape or the like needs to be devised.

The shoe sole <NUM> includes the bottom part <NUM> and the deformation restraining part <NUM>. The bottom part <NUM> includes the bottom surface part <NUM> that includes the rear bottom surface part <NUM> formed to extend from the rearfoot portion to the midfoot portion and to be, when the shoe sole is placed on the virtual surface S as a flat surface, in contact with the virtual surface S and that also includes the front bottom surface part <NUM> formed to continue to a front part of the rear bottom surface part <NUM> and also curvedly extend to the toe portion <NUM> such as to be spaced away from the virtual surface S. The deformation restraining part <NUM> is disposed in an edge part on a medial side and a lateral side of the bottom part <NUM> and extends from a forefoot portion to the midfoot portion along the bottom part <NUM>. Also, the deformation restraining part <NUM> has higher hardness than the bottom part <NUM>. The bottom part <NUM> further includes the upper surface part <NUM> that includes the first upper surface part <NUM> constituted by a surface formed to extend from the rearfoot portion to the midfoot portion and formed to be parallel with the virtual surface S or to extend downward from a rear part toward a front side in an unloading state and that also includes the second upper surface part <NUM> constituted by a surface formed to continue to a front end of the first upper surface part <NUM> and extend upward toward the front side to reach the toe portion <NUM>. A region facing an MP joint part of a foot is provided in the front bottom surface part <NUM> in the bottom surface part <NUM> and in the second upper surface part <NUM> in the upper surface part <NUM>. Accordingly, in the shoe sole <NUM>, since the downward inclination of the first upper surface part <NUM> toward the front side is maintained within a certain range, the upward inclination of the second upper surface part <NUM> toward the front side can be made gentle, so that excessive upward bending of the toe can be prevented.

The deformation restraining part <NUM> may be formed outside a region where a foot is in contact with the bottom part <NUM>. Accordingly, in the shoe sole <NUM>, the feeling of hardness on the medial side and the lateral side of the foot can be prevented.

In the deformation restraining part <NUM>, the medial side and the lateral side may be connected on the toe side. This facilitates the handling of the shoe sole <NUM> at the time of assembly and hence facilitates the assembly.

In the deformation restraining part <NUM>, the medial side may extend longer to the rearfoot portion than the lateral side. Accordingly, in the shoe sole <NUM>, the deformation on the medial side is restrained, and the restraint on the bending deformation in a vertical direction on the lateral side is eased.

The deformation restraining part <NUM> may be disposed closer to a vertically upper side of the bottom part <NUM>. Also, the bottom part <NUM> may be formed to cover a lower surface side of the deformation restraining part <NUM>. Accordingly, in the shoe sole <NUM>, the bonded part between the deformation restraining part <NUM> and the bottom part <NUM> is not exposed to the lower surface side, so that the durability can be improved.

The deformation restraining part <NUM> may be disposed closer to a vertically lower side of the bottom part <NUM>, and the outer sole <NUM> may be formed to cover a lower surface side of the deformation restraining part <NUM> and the bottom part <NUM>. Accordingly, in the shoe sole <NUM>, the bonded part between the deformation restraining part <NUM> and the bottom part <NUM> is protected by the outer sole <NUM>, so that the durability can be improved.

Also, an inner side surface of the deformation restraining part <NUM> intersecting a lateral direction of a foot may be inclined such as to extend inward in the lateral direction toward the lower side. Accordingly, in the shoe sole <NUM>, the feeling of hardness at a portion with which the foot comes into contact can be reduced.

Also, at least one of the bottom part <NUM> or the deformation restraining part <NUM> may be formed of a foam material. This can reduce the weight of the constituting members of the shoe sole <NUM>.

The shoe <NUM> includes any one of the shoe soles <NUM> described above, and the upper <NUM> disposed on the shoe sole <NUM>. Accordingly, the shoe <NUM> can ensure stability of landing of the rear bottom surface part <NUM> and also reduce the strain at the ankle joint during forward walking and running.

The present invention has been described with reference to embodiments. The embodiments are intended to be illustrative only, therefore the description in the present specification and the drawings should be regarded as exemplary rather than limitative.

Claim 1:
A shoe sole (<NUM>), comprising:
a bottom part (<NUM>) that includes a rear bottom surface part (<NUM>) formed to extend from a rearfoot portion to a midfoot portion and to be, when the shoe sole (<NUM>) is placed on a virtual surface as a flat surface, in contact with the virtual surface and that also includes a toe portion (<NUM>) of which a height from the virtual surface is set to <NUM>% or greater and <NUM>% or less with respect to a thickness dimension in the rear bottom surface part (<NUM>); and
a deformation restraining part (<NUM>) that is disposed in an edge part on a medial side and a lateral side of the bottom part (<NUM>) and extends from a forefoot portion to the midfoot portion along the bottom part (<NUM>) and that has higher hardness than the bottom part (<NUM>),
wherein the deformation restraining part (<NUM>) comprises a medial deformation restraining part (<NUM>) and a lateral deformation restraining part (<NUM>) that are disposed in recesses (<NUM>) provided in the edge part of the bottom part (<NUM>), and the edge part is outside a region of the bottom part (<NUM>) where a foot is in contact with the bottom part (<NUM>), and
wherein an inner side surface of the deformation restraining part (<NUM>) intersecting a lateral direction of a foot is inclined such as to extend inward in the lateral direction toward the lower side.