US20180199666A1 - Shoe having shoe sole with divided forefoot portion - Google Patents

Abstract

A main sole includes a toe-side first portion, a second portion arranged posterior to the first portion, and a third portion on a rear end side; and a first divide portion is defined by a first inclined surface extending in an upper-front diagonal direction at a rear surface of the first portion and a second inclined surface extending in an upper front diagonal direction at a front surface of the second portion.

Description

TECHNICAL FIELD
• The present invention relates to a shoe having a shoe sole with a divided forefoot portion.
BACKGROUND ART
• Shoes allowing users to run with a barefoot feel have recently been gaining popularity among some fans. These shoes are made to pursue a barefoot feel.
• A shoe sole is required to have various functions such as a flexible property and a shock-absorbing property. As one such flexible property, a shoe sole is required to flex in response to flexion of MP (metatarsal phalangeal) joints and IP (interphalangeal) joints of the forefoot section.
CITATION LISTPatent Literature
• First Patent Document: JP3,119,977U (front page)
• Second Patent Document: JP2007-89734A (front page)
• Third Patent Document: JP2000-197503A (front page)
• Fourth Patent Document: JP11-123101A (front page)
• Fifth Patent Document: JP2001-70004A (front page)
• Sixth Patent Document: JP2010-504839W (front page)
• Seventh Patent Document: WO2013/168259A1 (front page)
SUMMARY OF INVENTION
• JP3,119,977U discloses a shoe that aims at accommodating changes in the foot length during walk. This prior technique discloses grooves that allow for flexion at two locations in the front half of the shoe sole.
• With this prior technique, the upper is provided with an axis of flexion so that the insole stretches upon flexion.
• However, the lengths of toes and the joint heights of humans vary significantly. With the prior technique, the axis of flexion is provided at a particular position of the upper, and the center of flexion of the foot of the wearer often does not coincide with the axis of flexion.
• Moreover, the axis of flexion is arranged at a high position away from the upper surface of the shoe sole. Therefore, the insole needs to stretch significantly upon flexion, which will be a resistance against flexion.
• Moreover, it is not easy to precisely position a midsole and an outsole, which are divided into three parts in the front-rear direction, with respect to the upper. Therefore, the performance is likely to vary from one product to another.
• It is an object of the present invention to provide a shoe that easily flexes in response to flexion of joints in the forefoot section while running barefoot and whose performance is unlikely to vary from one product to another.
• WO2013/168259A1 proposes a shoe allowing the user to run without stress while maintaining its shock-absorbing property. This shoe is expected to suppress pronation of the heel portion occurring during the landing period while running, while maintaining its shock-absorbing property.
• However, this prior technique is not a proposal that pursues a barefoot feel. Therefore, it is not possible to realize barefoot-running joint movements.
• Therefore, it is another object of the present invention to provide a shoe that realizes joint movements close to barefoot-running joint movements while realizing a better shock-absorbing property than when running barefoot.
• One aspect of the present invention is directed to a shoe including an upper3 wrapping around an instep of a foot, aninsole4 being continuous with the upper3 and covering a sole of the foot, and a main sole MS covering theinsole4 from below and supporting the sole of the foot, wherein:
• • the main sole MS includes a toe-sidefirst portion11, and asecond portion12 arranged posterior DB to thefirst portion11;
  • a rear surface of thefirst portion11 includes oneinclined surface11F extending in an upper-front diagonal direction;
  • a front surface of thesecond portion12 includes anotherinclined surface12F extending in the upper-front diagonal direction;
  • the oneinclined surface11F of thefirst portion11 and the otherinclined surface12F of thesecond portion12 together define a first divide portion D1 at which thesurfaces11F,12F are in contact with each other or are capable of contacting each other;
  • abridging portion5F is provided, wherein thebridging portion5F is provided so as to bridge between thefirst portion11 and thesecond portion12 across the first divide portion D1, and thebridging portion5F connects between thefirst portion11 and thesecond portion12 so that the otherinclined surface12F of thesecond portion12 is rotatable relative to the oneinclined surface11F of thefirst portion11;
  • a part of thebridging portion5F is arranged between theinsole4 and thefirst portion11; and
  • another part of thebridging portion5F is arranged between theinsole4 and thesecond portion12.
• In this aspect, thebridging portion5F that connects between thefirst portion11 and thesecond portion12 is arranged between theinsole4 and thefirst portion11 and is arranged between theinsole4 and thesecond portion12. Therefore, thefirst portion11 and thesecond portion12, which are connected together via thebridging portion5F, can easily be positioned with respect to each other. This as a result improves the positioning precision between the main sole MS and the upper3, and the performance will be unlikely to vary from one product to another.
• When transitioning from foot-flat to heel-rise, the secondinclined surface12F of thesecond portion12 rotates at the first divide portion D1. Herein, the secondinclined surface12F extends in an upper-front diagonal direction, and thesecond portion12 will therefore rotate upward smoothly without being jammed between the road surface and thefirst portion11. As a result, the MP joints will flex smoothly, thereby realizing a running feel that is close to a barefoot feel.
• At heel-rise, the rear end portion of thefirst portion11 receives a large compressive load applied thereto at the heads of the metatarsal bones. Such a load will be easily supported by thefirst portion11 as theinclined surface11F of thefirst portion11 extends in an upper-front diagonal direction.
• As used in the present specification, inclined surfaces being in contact with each other means that at least a portion of one inclined surface is in contact with at least a portion of the other inclined surface when not worn. In this case, the load of the forefoot section when worn can easily be supported by the main sole MS.
• On the other hand, inclined surfaces being capable of contacting each other means that during the transition from heel-contact to heel-rise when worn, preferably at least at the stationary standing position ((load/shoe size)=1 kgf/cm), at least a portion of one inclined surface is in contact with at least a portion of the other inclined surface. In this case, the minimum value of the distance between these surfaces when not worn is preferably greater than 0.0 mm and less than 2.0 mm, and more preferably less than 1.0 mm, and most preferably less than 0.5 mm.
• The second aspect of the present invention is directed to a shoe including an upper3 wrapping around an instep of a foot, aninsole4 being continuous with the upper3 and covering a sole of the foot, and a main sole MS covering theinsole4 from below and supporting the sole of the foot, wherein:
• • the main sole MS includes a toe-sidefirst portion11, asecond portion12 arranged posterior DB to the first portion, and athird portion13 on a rear end side;
  • a rear surface of thefirst portion11 includes a firstinclined surface11F extending in an upper-front diagonal direction, and a front surface of thesecond portion12 includes a secondinclined surface12F extending in the upper-front diagonal direction;
  • the firstinclined surface11F and the secondinclined surface12F together define a first divide portion D1 at which thesurfaces11F,12F are in contact with each other or are capable of contacting each other;
  • a rear surface of thesecond portion12 includes a thirdinclined surface12B extending in an upper-rear diagonal direction, and a front surface of thethird portion13 includes a fourthinclined surface13B extending in the upper-rear diagonal direction; and
  • the thirdinclined surface12B and the fourthinclined surface13B together define a second divide portion D2 at which thesurfaces12B,13B are in contact with each other or are capable of contacting each other.
• In this aspect, during the period of transitioning from heel-contact, where only the heel contacts the ground, to foot-flat, where the sole of the foot entirely contacts the ground, thesecond portion12 and thethird portion13 can rotate relative to each other with the second divide portion D2 therebetween. This rotation will likely allow rotation of the subtalar joint STJ and the midtarsal joint MTJ of the foot.
• On the other hand, during the period of transitioning from foot-flat to heel-rise, it will allow smooth flexion of the MP joints as described above.
• Thus, the divided main sole MS allows flexion and rotation of various joints. As a result, one is likely to enjoy a running feel that is close to a barefoot feel.
• Note that the third and fourthinclined surfaces12B,13B of the second divide portion D2 extend in an upper-rear diagonal direction, and thethird portion13, which receives the load immediately after landing, therefore has a shape that flares downward. Therefore, the load will be easily supported by thethird portion13.
BRIEF DESCRIPTION OF DRAWINGS
• FIG. 1 is a medial side view showing a shoe according to one embodiment of the present invention.
• FIG. 2 is a lateral side view showing the same. Note that inFIG. 1 andFIG. 2, areas where mesh fabric is exposed is dotted.
• FIG. 3 is a perspective view showing a shoe sole as seen from the bottom surface side.
• FIG. 4 shows a bottom surface of the shoe sole.
• FIG. 5 is a plan view showing a midsole.
• FIG. 6A,FIG. 6B,FIG. 6C,FIG. 6D,FIG. 6E,FIG. 6F andFIG. 6G are cross-sectional views taken along respective lines shown inFIG. 4.
• FIG. 7 is an exploded perspective view of a midsole showing a first portion to a third portion separated from each other.
• FIG. 8 is an exploded perspective view showing an insole separated from a main sole. Note that inFIG. 8, the surface of the paddle is dotted.
• FIG. 9 is a lateral side view showing the shoe at heel-rise.
• FIG. 10 is a lateral side view showing the shoe at heel-contact.
• FIG. 11A,FIG. 11B andFIG. 11C are a medial side view, a plan view and a lateral side view, respectively, showing the foot bone structure.
• FIG. 12A andFIG. 12B are a back view and a perspective view of a worn shoe showing pronation and internal (medial) rotation of the foot, respectively.
• FIG. 13A,FIG. 13B,FIG. 13C,FIG. 13D andFIG. 13E are schematic lateral side views showing respective test samples. Note that in these figures, flexible portions are dotted.
• FIG. 14A,FIG. 14B andFIG. 14C are graphs showing test results.
• FIG. 15A,FIG. 15B andFIG. 15C are graphs showing test results.
• FIG. 16 is a lateral side view showing a shoe according to an alternative embodiment.
• FIG. 17A,FIG. 17B,FIG. 17C,FIG. 17D,FIG. 17E,FIG. 17F andFIG. 17G are cross-sectional views showing other alternative embodiments.
DESCRIPTION OF EMBODIMENTS
• In each of the aspects above, it is preferred that the bridgingportion5F is formed from a plate-shaped member that is separate (a different member) from the main sole MS.
• In this preferred example, it will be easier to manufacture the shoe sole as compared with a case where the bridgingportion5F is formed from the main sole MS.
• In each of the aspects above, it is more preferred that the shoe further includes first andsecond engagement portions11E and12E for positioning thebridging portion5F with respect to the main sole MS, wherein thefirst engagement portion11E is formed on an upper surface of thefirst portion11, and thesecond engagement portion12E is formed on an upper surface of thesecond portion12.
• In this case, the bridgingportion5F can easily be positioned with respect to thefirst portion11 and thesecond portion12. As a result, the positioning precision between thefirst portion11 and thesecond portion12 will further improve.
• More preferably, thefirst portion11 defines a first depression and thesecond portion12 defines a second depression; the bridgingportion5F fits into the first depression and the second depression; and the first depression forms thefirst engagement portion11E and the second depression forms thesecond engagement portion12E.
• In this case, the bridgingportion5F fits in the depressions of thefirst portion11 and thesecond portion12, and it is therefore easy to position the bridgingportion5F. As a result, the positioning precision between thefirst portion11 and thesecond portion12 will further improve.
• In each of the aspects above, an elastic modulus of the bridgingportion5F is equal to or greater than an elastic modulus of theinsole4.
• In this case, the bridgingportion5F having a large elastic modulus (Young's modulus) will suppress the inadvertent upward warping of thefirst portion11.
• In each of the aspects above, it is preferred that the first divide portion D1 has a shape that is protruding toward a front direction DF as seen in a plan view.
• The first divide portion D1 having such a protruding shape improves the positioning precision between thefirst portion11 and thesecond portion12.
• In each of the aspects above, it is preferred that the bridgingportion5F defines a through hole511, the through hole511 being arranged so as to extend from thefirst portion11 to thesecond portion12.
• In such a case, the main sole MS can easily flex at the bridgingportion5F.
• In each of the aspects above, it is preferred that awidth5W of the bridgingportion5F at the first divide portion D1 is set to be 25% to 100% of a width W of the main sole MS in (corresponding to) the first divide portion D1.
• The bridgingportion5F having alarge width5W improves the positioning precision.
• In each of the aspects above, it is preferred that a thickness of the bridgingportion5F is set to be 0.1 mm to 5.0 mm.
• In this case, the bridgingportion5F being thin contributes to maintaining a light weight, and awkwardness is unlikely to be felt on the sole of the foot.
• In each of the aspects above, it is preferred that a position of amedial edge1M of an upper end of the first divide portion D1 is set in a range of 65% to 75% from arear end1B of the main sole MS, with respect to a maximum length Lm from afront end1F to therear end1B of the main sole MS, along a center axis S extending in a front-rear direction FB of the main sole MS; and
• • a position of alateral edge1L of the upper end of the first divide portion D1 is set in a range of 60% to 70% from therear end1B of the main sole MS, with respect to the maximum length Lm of the main sole MS, along the center axis S of the main sole MS.
• In this case, the first divide portion D1 is likely to extend along a virtual line that connects together the heads of the metatarsal bones, as seen in a plan view.
• In each of the aspects above, it is preferred that a line obtained by aligning (tracing) an upper end of the first divide portion D1 with a width direction DW of the main sole MS is adapted to be arranged posterior DB to metatarsal phalangeal joints MP of a first toe B1 to a fifth toe B5 and is adapted to be arranged anterior DF to bases B11, B51 of first to fifth metatarsal bones.
• In this case, the first divide portion D1 is more likely to extend along the virtual line.
• In each of the aspects above, it is preferred that thefirst portion11 is continuous without being divided from the first divide portion D1 to a tip of the main sole MS.
• In this case, it is possible to prevent the bending feel at the toe from being discontinuous.
• More preferably, thefirst portion11 defines agroove11G, thegroove11G being shallower than a depth of the first divide portion D1 and extending in a width direction DW of the main sole MS.
• In this case, it is possible to realize smooth flexion of interphalangeal joints whose angle of flexion is smaller than that of MP joints.
• In each of the aspects above, it is preferred that the main sole MS includes anoutsole2 to be in contact with a road surface and amidsole1 arranged on theoutsole2; and
• • themidsole1 and theoutsole2 are each divided into parts in a front-rear direction at the first divide portion D1.
• The above-described advantages are likely to be realized as themidsole1 and theoutsole2 are each divided at the firstdivide portion D1.
• In the first aspect, it is preferred that the main sole MS includes athird portion13 arranged posterior DB to thesecond portion12;
• • a rear surface ofsecond portion12 and a front surface ofthird portion13 respectively include otherinclined surfaces12B,13B each extending in an upper-rear diagonal direction; and
  • theinclined surface12B of thesecond portion12 and theinclined surface13B of thethird portion13 together define a second divide portion D2 at which thesurfaces12B,13B are in contact with each other or are capable of contacting each other.
• In this case, it is possible to more easily realize a feel that is close to barefoot running, as described above.
• In each of the aspects above, it is preferred that the upper3 includes areinforcement portion36 obtained by reinforcing a midfoot portion of aside surface31,32 extending below (downward of) a wearing opening (topline)39, through which the foot is inserted; and
• • aflexible portion35 obtained by forming a forefoot portion of a side surface extending above (upward of) the first divide portion D1 so that theflexible portion35 is more flexible than thereinforcement portion36 so as to allow for rotation of thesecond portion12 while theinclined surface12F of thesecond portion12 moves in the upper-front diagonal direction.
• In this case, theflexible portion35 of the upper3 improves the degree of freedom in the flexion of the main sole MS at the first divide portion D1. Theflexible portion35 allows theinclined surface12F of thesecond portion12 to rotate while moving diagonally. Therefore, the first divide portion D1 will flex in accordance with the individual differences between wearers.
• On the other hand, the middle foot portion of the upper3 includes thereinforcement portion36 whose rigidity is greater than that of theflexible portion35, and the function of the upper3 of stably wrapping around the foot is unlikely to be lost.
• Any feature illustrated and/or depicted in conjunction with one of the aforementioned aspects or the following embodiments may be used in the same or similar form in one or more of the other aspects or other embodiments, and/or may be used in combination with, or in place of, any feature of the other aspects or embodiments.
EMBODIMENTS
• The present invention will be understood more clearly from the following description of preferred embodiments taken in conjunction with the accompanying drawings. Note however that the embodiments and the drawings are merely illustrative and should not be taken to define the scope of the present invention. The scope of the present invention shall be defined only by the appended claims. In the accompanying drawings, like reference numerals denote like components throughout the plurality of figures.
• Embodiment 1 of the present invention will now be described with reference toFIG. 1 toFIG. 10.
• The present embodiment is directed to a shoe sole of a shoe for running or walking, for example.
• A main sole MS shown inFIG. 1 includes a rubber-madeoutsole2 and a resin-mademidsole1. An upper3 wrapping around the instep of the foot is provided over the main sole MS.
• Themidsole1 includes a midsole body made of a resin-made foamed material such as EVA, for example, and may further include a reinforcement device. The term “made of resin” means that a resin component such as a thermoplastic component is contained, and may include any other suitable component. Apaddle5 ofFIG. 8 made of a high-resilience material, for example, is provided on the upper surface of themidsole1.
• Theoutsole2 ofFIG. 1 is a tread sole having a higher abrasion resistance than the foamed material of the midsole body, and typically has a higher hardness than the foamed material of the midsole body. Note that the term “made of rubber” means that it contains a natural rubber component or a synthetic rubber component, and it may contain any other component.
• As shown inFIG. 3 toFIG. 5, themidsole1 of the present embodiment and theinsole4 ofFIG. 8 generally cover the entire surface of the sole of the foot. On the other hand, as shown inFIG. 1 andFIG. 2, theoutsole2 is attached to the lower surface of themidsole1 and partially covers the sole of the foot. That is, the main sole MS ofFIG. 8 including themidsole1 and theoutsole2 covers theinsole4 from below and supports the sole of the foot.
• Theinsole4 ofFIG. 8 andFIG. 6B toFIG. 6G is continuous with the upper3 ofFIG. 2. The upper3 is shaped so as to wrap around the instep of the foot. Note that the shoe may include a shoelace for fitting the upper3 to the foot.
• The main sole MS is divided into a toe-sidefirst portion11, a second portion (rear portion)12 arranged posterior DB to the first portion, and a third portion13 (rear end portion) on the rear end side.
• The rear surface of thefirst portion11 includes a firstinclined surface11F extending in an upper-front diagonal direction. The front surface of thesecond portion12 includes a secondinclined surface12F extending in an upper-front diagonal direction. The firstinclined surface11F and the secondinclined surface12F together define a first divide portion D1 at which thesurfaces11F,12F are in contact with each other or are capable of contacting each other.
• The rear surface of thesecond portion12 includes a thirdinclined surface12B extending in an upper-rear diagonal direction.
• The front surface of thethird portion13 includes a fourthinclined surface13B extending in an upper-rear diagonal direction. The thirdinclined surface12B and the fourthinclined surface13B together define a second divide portion D2 at which thesurfaces12B,13B are in contact with each other or are capable of contacting each other.
• Themidsole1 and theoutsole2 are each divided into parts in a front-rear direction at the first and second divide portions D1, D2 (seeFIG. 7).
• As shown inFIG. 9, the secondinclined surface12F of thesecond portion12 is configured so that it can rotate relative to the firstinclined surface11F of thefirst portion11 in such a manner that the lower portion of the first divide portion D1 opens. As shown inFIG. 10, the fourthinclined surface13B of thethird portion13 is configured so that it can rotate relative to the thirdinclined surface12B of thesecond portion12 in such a manner that the lower portion of the second divide portion D2 opens.
• InFIG. 5, the position of themedial edge1M of the upper end of the first divide portion D1 is set in the range of 65% to 75%, from therear end1B of the main sole MS, of the maximum length Lm from thefront end1F to therear end1B of the main sole MS, along the center axis S (FIG. 4) extending in the front-rear direction FB of the main sole MS.
• The position of thelateral edge1L of the upper end of the first divide portion D1 is set in the range of 60% to 70%, from therear end1B of the main sole MS, of the maximum length Lm of the main sole MS, along the center axis S of the main sole MS.
• With the first divide portion D1 set in such a range, the line obtained by aligning the upper end of the first divide portion D1 with the width direction DW of the main sole MS is arranged posterior DB to the metatarsal phalangeal joints MP of the first toe B1 to the fifth toe B5 and is arranged anterior DF to the bases B11, B51 of the first to fifth metatarsal bones B1, B5. More preferably, the line is arranged posterior DB to the heads B12, B52 of the metatarsal bones. Note that the base refers to a portion of each bone that is close to a joint posterior thereto and that is slightly expanding to a greater thickness, and it is referred to also as the proximal head. On the other hand, the head refers to a portion of each bone that is close to a joint anterior thereto and that is slightly expanding to a greater thickness, and it is referred to also as the distal head.
• InFIG. 4, the first divide portion D1 has a shape that is protruding toward the front direction DF as seen in a plan view. On the other hand, the second divide portion D2 has a shape that is protruding toward the rear direction DB as seen in a plan view.
• In the present embodiment, thefirst portion11 is continuous without being divided from the first divide portion D1 to the tip of the main sole MS. Thefirst portion11 defines agroove11G, thegroove11G ofFIG. 1 being shallower than the depth of the first divide portion D1 and extending in the width direction DW of the main sole MS ofFIG. 4.
• The second portion (rear portion)12 extends toward the front direction DF from the rear surface. Thesecond portion12 defines agroove12G anterior DF to the rear surface. Thegroove12G is shallower than the depth of the second divide portion D2 (FIG. 1) and extends in the width direction W of the main sole MS.
• Next, thepaddle5 ofFIG. 8 will be described.
• Thepaddle5 is formed from a member different from the main sole MS. The elastic modulus of thepaddle5 is greater than or equal to the elastic modulus of theinsole4 and, more preferably, greater than the elastic modulus of theinsole4. Thepaddle5 is formed from a resin-made flat plate having a thickness of 0.1 mm to 5.0 mm, more preferably 0.5 mm to 1.5 mm.
• Thepaddle5 is arranged so as to extend across the first tothird portions11 to13. Thepaddle5 is sandwiched between the upper surface of themidsole1 and the lower surface of theinsole4. Thepaddle5 includes a bridgingportion5F on the forefoot side, and a bridgingportion5B on the rear foot side.
• A portion of the bridgingportion5F on the forefoot side ofFIG. 8 is arranged between theinsole4 and thefirst portion11. On the other hand, another portion of the bridgingportion5F is arranged between theinsole4 and thesecond portion12.
• A portion of the bridgingportion5B on the rear foot side is arranged between theinsole4 and thesecond portion12. On the other hand, another portion of the bridgingportion5B is arranged between theinsole4 and thethird portion13.
• In order for the bridgingportion5F on the forefoot side ofFIG. 8 to be positioned with respect to the main sole MS, thefirst engagement portion11E is formed on the upper surface of thefirst portion11 and thesecond engagement portion12E is formed on the upper surface of thesecond portion12. Thefirst portion11 and thesecond portion12 ofFIG. 7 define the first depression and the second depression, respectively, into which thebridging portion5F (FIG. 8) fits, wherein the first depression and the second depression form the first andsecond engagement portions11E and12E, respectively.
• In order for the bridgingportion5B on the rear foot side ofFIG. 8 to be positioned with respect to the main sole MS, thesecond engagement portion12E is formed on the upper surface of thesecond portion12 and thethird engagement portion13E is formed on the upper surface of thethird portion13. Thesecond portion12 and thethird portion13 ofFIG. 7 each define a depression into which the bridgingportion5B (FIG. 8) fits, wherein the depressions form therespective engagement portions11E,12E.
• InFIG. 5, the widths5Wf, Wb of thebridging portions5F,5B of the first and second divide portions D1, D2 are each set to be 25% to 100% of the width W of the main sole MS.
• InFIG. 8, the bridgingportions5F,5B define a plurality of through holes511. The through holes511 on the forefoot side are arranged so as to extend from thefirst portion11 to thesecond portion12. The through holes511 on the rear foot side are arranged so as to extend from thesecond portion12 to thethird portion13.
• Note that it is preferred that the through holes511 on the rear foot side are so structured that thethird portion13 can easily be displaced in the width direction DW.
• The bridgingportion5F on the forefoot side ofFIG. 8 is provided so as to bridge between thefirst portion11 and thesecond portion12 across the first divide portion D1, and the bridgingportion5F connects between thefirst portion11 and thesecond portion12 so that theinclined surface12F of thesecond portion12 is rotatable relative to theinclined surface11F of thefirst portion11, as shown inFIG. 9.
• The bridgingportion5B on the rear foot side ofFIG. 8 is provided so as to bridge between thesecond portion12 and thethird portion13 across the second divide portion D2, and the bridgingportion5B connects between thesecond portion12 and thethird portion13 so that theinclined surface12B of thesecond portion12 is rotatable relative to theinclined surface13B of the third portion, as shown inFIG. 10.
• InFIG. 4, the second divide portion D2 includes adiagonal portion131 that extends toward the lateral side in a diagonal forward direction DF from acentral portion13C between the medial side and the lateral side. The angle α formed between a virtual transverse (horizontal) line VL that is perpendicular to the center axis S extending in the front-rear direction FD of the main sole MS and thediagonal portion131 of the second divide portion D2 is set in a range of 10° to 40°.
• Themedial edge1M of the second divide portion D2 is arranged posterior DB to thelateral edge1L of the second divide portion D2.
• In the rear foot portion, amedial side surface31 of the upper3 ofFIG. 1 includes a medial-side high rigidity portion3111 and a medial-sideflexible portion31S that is more flexible than the medial-side high rigidity portion3111, which are separated from each other in the front-rear direction. Alateral side surface32 of the upper3 ofFIG. 2 includes a lateral-side high rigidity portion3211 and a lateral-sideflexible portion32S that is more flexible than the lateral-side high rigidity portion3211.
• The front edge portion of the medial-side high rigidity portion3111 and/or the medial-sideflexible portion31S ofFIG. 1 extend in an upper-rear diagonal direction from the upper end portion of themedial edge1M of the second divide portion D2. The front edge portion of the lateral-side high rigidity portion3211 and/or the lateral-sideflexible portion32S ofFIG. 2 extend in an upper-rear diagonal direction from the upper end portion of thelateral edge1L of the second divide portion D2. Note that the term “from the upper end portion” means from the upper end or a vicinity thereof.
• The high rigidity portions may each be formed from a synthetic-resin plate, for example. The low rigidity portions may each be formed from a fabric (cloth) such as a mesh fabric, a knit fabric, a woven fabric or a non-woven fabric, for example.
• A plurality of strip-shapedrestraining members34M are arranged on the medial-sideflexible portion31S ofFIG. 1 for restraining the stretch of the medial-sideflexible portion31S in the front-rear direction FB. Another plurality of strip-shapedrestraining members34L are arranged on the lateral-sideflexible portion32S ofFIG. 2 for restraining the stretch of the lateral-sideflexible portion32S in the front-rear direction FD.
• The restraining members may be a comb-shaped thin film bonded or welded (including transfer printing) on the surface of the mesh fabric.
• In the forefoot portion, including directly above the first divide portion D1, theflexible portion35 of the upper3 is formed from a low rigidity material, e.g., a cloth-like fabric such as a mesh fabric, a knit fabric, a woven fabric or a non-woven fabric, for example. Theflexible portion35 as described above allows theinclined surface12F of thesecond portion12 to rotate while moving in an upper-front diagonal direction as shown inFIG. 9.
• Next, a part of a shoe manufacturing process will be described.
• As shown inFIG. 8, thepaddle5 is adapted to theengagement portions11E to13E, which are depressions in the first, second andthird portions11 to13, thereby attaching (bonding) thepaddle5 to the upper surface of themidsole1. Thus, thefirst portion11 and thesecond portion12 are positioned with respect to each other, and thesecond portion12 and thethird portion13 are positioned with respect to each other.
• Themidsole1, which is made integral by means of thepaddle5, is bonded to the reverse surface of theinsole4, which is integral with the upper3 (not shown;FIG. 1). At this point, although theinsole4 and the upper3 are surrounded by a last well known in the art, themidsole1 is not divided in the front-rear direction as described above so that themidsole1 can easily be positioned with respect to theinsole4 at the time of bonding.
• Next, the behavior of the forefoot portion of the shoe while running will be described.
• When not worn (FIG. 2), the firstinclined surface11F and the secondinclined surface12F of the first divide portion D1 are partly in contact with each other, and there may be a slight gap between the firstinclined surface11F and the secondinclined surface12F of the first divide portion D1 due to manufacturing errors. However, at the standstill position with the shoe on or at foot-flat while running, the firstinclined surface11F and the secondinclined surface12F contact each other with a strong pressure due to compressive deformation of themidsole1, etc. Therefore, it will be possible to stably support the foot.
• At heel-rise, the upper3 and the main sole MS flex as shown inFIG. 9, and thesecond portion12 is displaced so as to rotate relative to thefirst portion11. As described above, themidsole1 is attached to the upper3 via the paddle5 (FIG. 8). Therefore, thesecond portion12 rotates, relative to thefirst portion11, about the vicinity of the upper end of the first divide portion D1.
• On the other hand, although the forefoot portion of the upper3 is compressed, theflexible portion35 of the upper3 directly above, and anterior/posterior to, the first divide portion D1 of the present embodiment is formed from a flexible material such as a mesh fabric described above, for example, and theflexible portion35 can easily be creased35W, thereby making it unlikely that the rotation is inhibited. For example, theflexible portion35 has no defined center of flexion, and therefore theinclined surface12F of thesecond portion12 rotates while moving in the upper-front diagonal direction in accordance with the flexion of the foot.
• Next, the structure of the rear foot section of a human will be described briefly with reference toFIG. 11A toFIG. 12B.
• As shown inFIG. 11A toFIG. 11C, the subtalar joint (STJ) and the midtarsal joint (MTJ) exist below the ankle. These joints STJ and MTJ can rotate about the axis Ss and the axis Sm, respectively. These axes Ss and Sm are orthogonal to intersecting planes Bs, Bm. The intersecting planes Bs, Bm are inclined planes that are inclined by about 42° and 15° with respect to the vertical plane inFIG. 11A andFIG. 11C. The intersecting planes Bs, Bm are also inclined planes that are inclined by about 20° and 9° with respect to the longitudinal axis of the foot inFIG. 11B.
• Considering the angles of the intersecting planes, the angle α2 formed between theinclined surfaces12B,13B of the second divide portion D2 ofFIG. 2 and the vertical plane is preferably about 5° to 45° on the lateral side of the foot, more preferably about 10° to 40°, and most preferably about 15° to 35°.
• On the other hand, the angle α1 between theinclined surfaces12F,13F of the first divide portion D1 ofFIG. 2 and the vertical plane is preferably about 20° to 70° on the lateral side of the foot, more preferably about 25° to 65°, and most preferably about 30° to 60°.
• Next, the mechanism of the pronation occurring while running will be described briefly.
• After landing while running, first, the joint STJ ofFIG. 11A toFIG. 11C rotates, and the heel thereby pronates as shown inFIG. 12A. Then, the joint MTJ rotates in conjunction with the rotation of the joint STJ ofFIG. 11A toFIG. 11C, and the lower leg thereby medially rotates as shown inFIG. 12B. Thus, pronation occurs. In order to realize movements of joints that are close to barefoot running, it is believed that there is a need for a shoe structure that allows, without inhibiting, the action of the joints STJ, MTJ, the pronation and the internal rotation.
• Next, the behavior of the rear foot portion of the foot while running will be described.
• In the main sole MS of the embodiment ofFIG. 1, the second divide portion D2 of the rear foot section extends in an upper-rear diagonal direction, the second divide portion D2 ofFIG. 5 includes thediagonal portion131 on the lateral side. Therefore, immediately after landing such as first strike ofFIG. 10, the lower portion of the second divide portion D2 is displaced so as to open, and it is unlikely to inhibit the action of the joints STJ, MTJ ofFIG. 11A toFIG. 11C, the pronation ofFIG. 12A and the internal rotation ofFIG. 12B. Therefore, it is likely to realize an action of pronation that is proximate to that during barefoot running.
• On the other hand, immediately after landing, a large impact load is applied to thethird portion13 ofFIG. 10. However, at the second divide portion D2, thethird portion13 and thesecond portion12 are in contact with each other and are separated from each other. Therefore, thethird portion13, which is separated from thesecond portion12, will easily deform after landing. Therefore, a good shock-absorbing property will be realized.
• During the transition from heel-contact ofFIG. 10 to foot-flat ofFIG. 2, thesecond portion12 is in contact with thethird portion13. Therefore, the transition will go smoothly. Thus, it is likely that movements of joints during barefoot running will be realized.
• Immediately after landing as shown inFIG. 10, the main sole MS flexes, and thethird portion13 is displaced so as to rotate relative to thesecond portion12. As described above, themidsole1 is attached to the upper3 via the paddle5 (FIG. 8). Therefore, thethird portion13 rotates, relative to thesecond portion12, about the vicinity of the upper end of the second divide portion D2.
• On the other hand, as can be seen from a comparison betweenFIG. 2 andFIG. 10, at heel-contact immediately after landing, an area of the upper3 that is in an upper-rear diagonal direction of the second divide portion D2 is compressed as the third portion rotates relative to thesecond portion12. Since the upper3 of the present embodiment includes theflexible portions32S,31S (FIG. 1), theflexible portions32S,31S (FIG. 1) ofFIG. 2 will easily contract (creating creases) as shown inFIG. 10. Thus, the rotation at the second divide portion D2 is unlikely to be inhibited.
• At heel-rise ofFIG. 9, the heel of the foot is likely to rise inside the upper3. In the present embodiment, while theflexible portions32S,31S (FIG. 1) are present, the restrainingmembers34L,34M (FIG. 1) are provided on theflexible portions32S,31S (FIG. 1). Therefore, it is possible to restrain the stretch of the flexible portion of the upper3 at heel-rise, and it is as a result possible to prevent the heel from rising inside the upper3.
• Next, a reference example and test examples will be illustrated in order to elucidate the advantageous effects of the present embodiment.
• First, as a reference example, test sample T1 ofFIG. 13A was provided that did not have the divide portions D1, D2. On the other hand, test samples T2 to T5 ofFIG. 13B toFIG. 13E were provided as test examples.
• In sample T2, the main sole MS is divided along a plane that is orthogonal to the axis Ss (FIG. 11A). In sample T3, the main sole MS is divided at four divide portions D1, D2, D11, D21 along planes that are orthogonal to the axis Ss (FIG. 11A) and the axis Sm (FIG. 11A). In samples T4 and T5, diagonalflexible portions33S are provided on the medial side and the lateral side of the upper3 so as to function in conjunction with the divide portions D1, D2 of samples T2 and T3. Note that sample T1 is not provided with the divide portions and the flexible portions.
• A test experiment was conducted with one subject at a running speed of 4 min/km. Comparisons were made between running with shoes ofFIG. 13A toFIG. 13E and running barefoot. The flexion/extension angle of the foot joint was measured while running, and the ground reaction force was measured in the front-rear direction and in the vertical direction.
• Then, the maximum propulsion force and the propulsion impulse (impulse product) were calculated from the angle and the ground reaction force in the front-rear direction. The values are shown inFIG. 14A andFIG. 14B. These graphs indicated that samples T2, T3, T4, T5 having the divide portions, as compared with barefoot and sample T1, required a greater maximum propulsion force and a greater propulsion impulse while running at the same speed.
• FIG. 14C shows a comparison result for the work of the foot joint required for push-off. As can be seen from the figure, the amount of work is greater for samples T2, T3, T4, T5 provided with the divide portions than for barefoot and sample T1. It can be seen that this resulted in a greater load on the lower leg.
• The reason for such results is assumed to be because the triceps of the lower leg, which are important for running, are used more due to the significant decrease in the rigidity of the main sole MS. Therefore, by running with these shoes on, one can expect a high effectiveness in training.
• Then, the heel portion pronation angle β and the lower leg internal rotation angle γ ofFIG. 12A andFIG. 12B were calculated from the flexion/extension angle. The results are shown inFIG. 15A andFIG. 15B. As a result of comparing the heel portion pronation angle β, it can be seen that sample T1 has a greater absolute value of the pronation angle β than barefoot, whereas samples T2, T3, T4, T5 have joint angles closer to barefoot running. As for the lower leg internal rotation angle γ, sample T1 has a smaller absolute value of the internal rotation angle γ than barefoot, whereas samples T2, T3, T4, T5 have joint angles closer to barefoot running.
• Therefore, it can be seen that with the provision of the second divide portion D2 ofFIG. 10, more preferably with the provision of thegroove12G and theflexible portions32S,31S (FIG. 1), it is possible to realize a shoe with which joint movements are closer to barefoot running.
• Then, the value of the impact load was calculated by dividing the ground reaction force in the vertical direction by the unit time. The results are shown inFIG. 15C. It can be seen from the figure that samples T2, T3, T4, T5 have an equivalent shock-absorbing property to sample T1, and have a good shock-absorbing property with a smaller impact value than barefoot.
• Samples T2 to T5 ofFIG. 13B toFIG. 13E were produced by modifying the main sole MS and the upper3 of existing shoes. Therefore, they do not have the paddle (FIG. 8).
• A shoe of the present invention may have a structure like those of samples T2 to T5, or may have a structure of samples T2 to T5 with the paddle (FIG. 8) added thereto.
• The bridgingportions5F,5B of thepaddle5 ofFIG. 8 may be separated from each other. However, thepaddle5 being continuous from thefirst portion11 to thethird portion13 has a greater Young's modulus than themidsole1, and will be useful as a reinforcement device of thesecond portion12.
• When thepaddle5 ofFIG. 8 is provided, the through holes511 do not need to be provided in thepaddle5. When the through holes511 are provided, protruding portions may be formed on the upper surface of themidsole1 so as to correspond to the through holes511, so that the upper surface of themidsole1 in the through holes511 is set to be at about the same level (height) as the upper surface of thepaddle5.
• As in the alternative example ofFIG. 16, this shoe may be provided with grooves Gm arranged in a staggered pattern on the lower surface of the main sole MS and on the upper surface of the main sole MS.
• FIG. 17A toFIG. 17D show alternative examples.
• As shown in the examples of these figures, at the divide portions D1, D2, thesections11,12,13 of the main sole may be in contact with each other via bridgingportions5F,5B that are protruding downward. At the divide portions D1, D2, the bridgingportions5F,5B may be such that the midsoles are not in direct contact with each other, but outsoles are in direct or indirect contact with each other.
• FIG. 17E toFIG. 17G show other alternative examples.
• In these figures, the upper surface of themidsole1 is attached to the lower surface of theinsole4, and the paddle5 (FIG. 8) is absent. In these cases, themidsoles1 may be bound together in areas other than the divide portions D1, D2 via a bonded or weldedattachment portion19 that is dotted in the figure. That is, themidsole1 may form thebridging portions5F,5B.
• While preferred embodiments have been described above with reference to the drawings, various obvious changes and modifications will readily occur to those skilled in the art upon reading the present specification.
• For example, the midsole may be provided with gel or pod-like shock-absorbing parts. The main sole may be formed solely from a flexible midsole-like material or solely from an outsole.
• Thus, such changes and modifications are deemed to fall within the scope of the present invention.
INDUSTRIAL APPLICABILITY
• The present invention is applicable to various shoes for running, walking, training, etc.
REFERENCE SIGNS LIST
• 1: Midsole,2: Outsole
• 1B: Rear end,1F: Front end,1L: Lateral edge,1M: Medial edge
• 11: First portion,11E: First engagement portion,11F: First inclined surface,11G: Groove
• 12: Second portion,12B: Third inclined surface,12E: Second engagement portion,12F: Second inclined surface,12G: Groove
• 13: Third portion,13B: Fourth inclined surface,13C: Central portion,
• 13E: Engagement portion
• 131: Diagonal portion,19: Attachment portion
• 3: Upper,31: Medial side surface,31H: Medial-side high rigidity portion,31S: Medial-side flexible portion
• 32: Lateral side surface,32H: Lateral-side high rigidity portion,32S: Lateral-side flexible portion,33S: Flexible portion
• 34L: Restraining member,34M: Restraining member,35: Flexible portion,36: Reinforcement portion
• 39: Wearing opening
• 4: Insole
• 5: Paddle,5B: (Second) bridging portion,5F: (First) bridging portion,5H: Through hole,5W: Width
• B1: First toe, B5: Fifth toe, Bc: Calcaneal bone
• Bs, Bm: Intersecting plane
• D1: First divide portion, D2: Second divide portion, D11, D21: Divide portion
• DB: Posterior, DF: Anterior, DW: Width direction, FB: Front-rear direction
• Lm: Maximum length
• MP: Metatarsal phalangeal joint, MS: Main sole
• STJ, MTJ: Joint
• S: Center axis, Ss, Sm: Axis
• V1: Transverse line
• W, Wb: Width
• α, β, γ: Angle

Claims (17)

1. A shoe comprising: an upper configured to wrap around an instep of a foot; an insole being continuous with the upper and configured to cover a sole of the foot; and a main sole covering the insole from below and configured to support the sole of the foot, wherein:

the main sole includes a toe-side first portion, and a second portion arranged posterior to the first portion;

a rear surface of the first portion includes one inclined surface extending in an upper-front diagonal direction;

a front surface of the second portion includes another inclined surface extending in the upper-front diagonal direction;

the one inclined surface of the first portion and the other inclined surface of the second portion together define a first divide portion at which the surfaces are in contact with each other or are capable of contacting each other;

a bridging portion is provided, wherein the bridging portion is provided on the first portion and the second portion so as to bridge the first divide portion, and the bridging portion connects between the first portion and the second portion so that the other inclined surface of the second portion is rotatable relative to the one inclined surface of the first portion;

a part of the bridging portion is arranged between the insole and the first portion; and

another part of the bridging portion is arranged between the insole and the second portion.

2. The shoe according toclaim 1, wherein the bridging portion is formed from a plate-shaped member that is separate from the main sole.

3. The shoe according toclaim 2, further comprising a first engagement portion and a second engagement portion both for positioning the bridging portion with respect to the main sole, wherein the first engagement portion is formed on an upper surface of the first portion, and the second engagement portion is formed on an upper surface of the second portion.

4. The shoe according toclaim 3, wherein the first portion and the second portion define a first depression and a second depression, respectively, into which the bridging portion fits, and the first depression and the second depression form the first engagement portion and the second engagement portion, respectively.

5. The shoe according toclaim 2, to wherein an elastic modulus of the bridging portion is equal to or greater than an elastic modulus of the insole.

6. The shoe according toclaim 2, wherein the first divide portion has a shape that is protruding toward a front direction as seen in a plan view.

7. The shoe according toclaim 2, wherein the bridging portion defines a through hole, the through hole being arranged so as to extend from the first portion to the second portion.

8. The shoe according toclaim 2, wherein a width of the bridging portion in the first divide portion is set to be 25% to 100% of a width of the main sole in the first divide portion.

9. The shoe according toclaim 2, wherein a thickness of the bridging portion is set to be 0.1 mm to 5.0 mm.

10. The shoe according toclaim 1, wherein:

a position of a medial edge of an upper end of the first divide portion is set in a range of 65% to 75% from a rear end of the main sole, with respect to a maximum length from a front end to the rear end of the main sole, along a center axis extending in a front-rear direction of the main sole; and

a position of a lateral edge of the upper end of the first divide portion is set in a range of 60% to 70% from the rear end of the main sole, with respect to the maximum length of the main sole, along the center axis of the main sole.

11. The shoe according toclaim 1, wherein:

a line obtained by aligning an upper end of the first divide portion with a width direction of the main sole is adapted to be arranged posterior to metatarsal phalangeal joints of a first toe to a fifth toe and is adapted to be arranged anterior to bases of first to fifth metatarsal bones.

12. The shoe according toclaim 1, wherein the first portion11 is continuous without being divided from the first divide portion to a tip of the main sole.

13. The shoe according toclaim 12, wherein the first portion defines a groove, the groove being shallower than a depth of the first divide portion and extending in a width direction of the main sole.

14. The shoe according toclaim 1, wherein:

the main sole includes an outsole to be in contact with a road surface and a midsole arranged on the outsole; and

the midsole and the outsole are each divided into parts in a front-rear direction at the first divide portion.

15. The shoe according toclaim 1, wherein:

the main sole includes a third portion arranged posterior to the second portion;

a rear surface of the second portion and a front surface of the third portion each include still another inclined surface extending in an upper-rear diagonal direction; and

the still other inclined surface of the second portion and the still other inclined surface of the third portion together define a second divide portion at which the still other surfaces are in contact with each other or are capable of contacting each other.

16. A shoe comprising: an upper configured to wrap around an instep of a foot; an insole being continuous with the upper and configured to cover a sole of the foot; and a main sole covering the insole from below and configured to support the sole of the foot, wherein:

the main sole includes a toe-side first portion, a second portion arranged posterior to the first portion, and a third portion on a rear end side;

a rear surface of the first portion comprises a first inclined surface extending in an upper-front diagonal direction, and a front surface of the second portion comprises a second inclined surface extending in the upper-front diagonal direction;

the first inclined surface and the second inclined surface together define a first divide portion at which the first inclined surface and the second inclined surface are in contact with each other or are capable of contacting each other;

a rear surface of the second portion comprises a third inclined surface extending in an upper-rear diagonal direction, and a front surface of the third portion comprises a fourth inclined surface extending in the upper-rear diagonal direction; and

the third inclined surface and the fourth inclined surface together define a second divide portion at which the third inclined surface and the forth inclined surface are in contact with each other or are capable of contacting each other.

17. The shoe according toclaim 1, wherein the upper includes:

a reinforcement portion obtained by reinforcing a midfoot portion of a side surface extending below a wearing opening, configured so that the foot is inserted therethrough; and

a flexible portion obtained by forming a forefoot portion of a side surface extending above the first divide portion so that the flexible portion is more flexible than the reinforcement portion so as to allow for rotation of the second portion while the inclined surface of the second portion moves in the upper-front diagonal direction.

Images