Shock absorber, shoe sole and shoe
A shock absorber includes a three-dimensional structure composed of a unit structure repeatedly, regularly and continuously arranged in at least one direction, the unit structure being a three-dimensional shape formed by a wall having an external shape defined by a pair of parallel planes or curved surfaces. When the unit structure occupies a cuboidal space representing a unit space and defined by mutually orthogonal three sides having a first side extending in an axial direction in which the shock absorber exhibits a shock absorbing function as the shock absorber receives a load and second and third sides each extending from one end of the first side in a direction orthogonal to the axial direction, and the first side has a length L 1 and a longer one of the second and third sides has a length L 2 , the shock absorber satisfies 1.1≤L 1 /L 2 ≤4.0.
1. A shoe sole comprising a shock absorber comprising a three-dimensional structure composed of a unit structure repeatedly, regularly and continuously arranged in three orthogonal axial directions, the unit structure being a three-dimensional shape formed by a wall having an external shape defined by a pair of parallel planes or curved surfaces,
each unit structure having a cavity therein,
an axial direction of the three orthogonal axial directions being orthogonal to a tread, the axial direction being a direction in which the shock absorber exhibits a shock absorbing function as the shock absorber receives a load,
a cavity of any one unit structure communicating with any cavity of each of other unit structures adjacent to the one unit structure in the three orthogonal axial directions, in a direction in which the one unit structure is adjacent to each of the other unit structures,
wherein
such unit structures each occupy an approximate rectangular parallelopiped space representing a unit space and are defined by mutually orthogonal three sides having a first side extending in the axial direction and second and third sides each extending from one end of the first side in a direction orthogonal to the axial direction, and the first side has a length L 1 and a longer one of the second and third sides has a length L 2 , the three-dimensional structure including the unit structure satisfying 1.1≤L 1 /L 2 ≤4.0,
the wall of the three-dimensional structure has a meandering portion which is a portion presenting a cross-sectional shape extending in a meandering manner when the three-dimensional structure is cut along at least a specific plane,
the meandering portion has an integrally-formed reinforcement portion to reinforce a turning point of the meandering portion, and
the integrally-formed reinforcement portion is an additional thickness portion of the wall consisting of the same material as the wall and provided at an internal corner portion of the turning point to make the turning point larger in thickness and in compressive stiffness than another portion of the wall.
2. The shoe sole according to claim 1 , wherein such unit spaces aligned in the axial direction each have an equal L 1 /L 2 .
3. The shoe sole according to claim 1 , wherein the three-dimensional structure is a triply periodic minimal surface with a thickness added thereto.
4. The shoe sole according to claim 3 , wherein the three-dimensional structure has a Schwarz' P structure or a gyroid structure.
5. The shoe sole according to claim 1 , wherein the three-dimensional structure is composed of a plurality of planes disposed to intersect with one another with a thickness added thereto so that the three-dimensional structure has a cavity therein.
6. A shoe comprising:
a shoe sole according to claim 1 ; and
an upper provided above the shoe sole.
7. The shoe sole according to claim 1 , wherein the additional thickness portion of the wall comprises a protrusion at the internal corner portion of the turning point or a fill portion at the internal corner portion extending across the internal corner portion.