Patent Publication Number: US-2023138934-A1

Title: Shock-absorbing Structure for a Sole and Sole for a Shoe having Same

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a shock-absorbing structure for a sole and a sole for a shoe having the shock-absorbing structure, and more specifically to a structural improvement for improving cushioning properties, resilience and durability. 
     As a shock-absorbing structure, for example, Japanese patent No. 3337971 (hereinafter referred to as JP ‘971) discloses a structure in which a plurality of band-shaped wavy sheets are disposed side by side in the lateral direction and the adjacent band-shaped wavy sheets are interconnected via connecting bars (see paragraphs 0053, 0054 and  FIGS.  1 ,  2   ). 
     When a shock load is imparted to the shock-absorbing structure from above, the respective band-shaped wavy sheets compressive-deform in the up-down direction (see paragraph 0056 and  FIG.  3   ). At this time, the connecting bars are twisted by the respective band-shaped wavy sheets that compressive-deform and thus act as torsion bars, thereby absorbing the shock load in conjunction with deformations of the respective wavy shapes of the respective band-shaped wavy sheets (see paragraph 0057). 
      Also, the above-mentioned JP ‘971 discloses the structure in which the front and rear end portions of the respective band-shaped wavy sheets are interconnected by a joining portion (see paragraph 0059 and  FIG.  5   ). In this case, when the shock load acts, a longitudinal elongation due to the compressive deformation of the respective band-shaped wavy sheets is restrained by the joining portion, such that thereby the shock load can be absorbed more efficiently in conjunction with the deformation of the respective wavy shapes of the respective band-shaped wavy sheets and the torsional deformation of the connecting bars (see paragraph 0060). 
     The patent application publication No. 2021-70358 (hereinafter referred to as JP ‘358) discloses an energy absorbing structure, which is provided between the seat body of the seat for an aircraft and the floor portion of the multicopter to absorb a touchdown impact of the multicopter at the time of a crash landing (see paragraph 0044 and  FIG.  2   ). The energy absorbing structure has a heteromorphic honeycomb structure that is sandwiched in the up-down direction between the bottom surface of the seat cushion and the floor portion. The heteromorphic honeycomb structure is formed in such a way that a plurality of corrugated structures each having a wavy shape are stacked in the up-down direction (see paragraph 0074 and  FIG.  13   ). 
     When a touchdown impact acts on the energy absorbing structure in the up-down direction, the respective corrugated structures deform to be crashed in the up-down direction. Thereby, a large energy absorption can be achieved with a short stroke (paragraph 0076 and  FIGS.  14 A to  14 E ). 
     However, in the shock-absorbing structure described in the above-mentioned JP ‘971, the respective band-shaped wavy sheets adjacent to one another in the lateral direction are interconnected by the connecting bars and the connecting bars are twisted every time the respective band-shaped wavy sheets compressive-deform, which requires durability of the connecting bars in addition to durability of the respective band-shaped wavy sheets. 
     Also, in the energy absorbing structure described in the above-mentioned JP ‘358, when the heteromorphic honeycomb structure deforms the respective corrugated structures deform to be crashed in the up-down direction. Therefore, the energy absorbing structure is structured in the light of absorbing the touchdown impact in the crash landing or the like and thus it does not consider resilience in absorbing an impact. 
     The present invention has been made in view of these circumstances and its object is to provide a shock-absorbing structure for a sole that can improve cushioning properties and resilience and that can enhance durability. 
     Other objects and advantages of the present invention will be obvious and appear hereinafter. 
     SUMMARY OF THE INVENTION 
     A shock-absorbing structure for a sole according to the present invention includes a wavy sheet laminated body in which a plurality of wavy sheets of a wave shape are laminated in the up-down direction to compose three or more layers, one-end sidewall portion provided at one end side in the wave direction of the wave shape of the wavy sheet laminated body and restraining the plurality of wavy sheets, the other-end sidewall portion provided at the other end side in the wave direction of the wave shape of the wavy sheet laminated body and restraining the plurality of wavy sheets, and a connecting portion in which at least a portion of a contact region of the plurality of wavy sheets is connected to one another. 
     Here, for explanatory convenience, a structure in which the wavy sheets are laminated in three layers is taken for example. The respective laminated wavy sheets are referred to as a first wavy sheet, a second wavy sheet, and a third wavy sheet, from top to bottom. 
     According to the shock-absorbing structure of the present invention, a load imparted to the first wavy sheet is transferred to the second wavy sheet through the contact area of the first wavy sheet with the second wavy sheet, and further transferred to the third wavy sheet through the contact area of the second wavy sheet with the third wavy sheet. Thereby, when the load acts to the shock-absorbing structure, the respective wavy sheets laminated in the up-down direction disperse the load to compressive-deform respectively in the up-down direction, thus effectively absorbing the load to improve cushioning properties. 
     Moreover, according to the present invention, there are provided one-end sidewall portion at one end side and the other-end sidewall portion at the other end side in the wave direction of the wave shape of the wavy sheet laminated body to restrain the plurality of wavy sheets respectively, which causing an elongation of the one end side and the other end side in the wave direction of the wave shape of the wavy sheet laminated body to be restrained when the respective wavy sheets compressive-deform at the time of loading. Thereby, at the time of compressive deformation of the respective wavy sheets, the respective wavy sheets can effectively accumulate an elastic energy. As a result, the accumulated elastic energy can be released after unloading thus enhancing resilience. 
     Furthermore, according the present invention, the respective wavy sheets laminated in the up-down direction are connected to one another at least at a portion of the contact are of the respective wavy sheets as a connecting portion without a member different from the wavy sheets, thus improving durability of the entire shock-absorbing structure. 
     The shock-absorbing structure may further include an upper-side wall portion provided on and cover the upper side of the wavy sheet laminated body and a lower-side wall portion provided on and cover the lower side of the wavy sheet laminated body. The upper-side wall portion and the lower-side wall portion may be connected to the one-end sidewall portion and the other-end sidewall portion respectively. The wavy sheet laminated body may be surrounded by the one-end sidewall portion, the other-end sidewall portion, the upper-side wall portion and the lower-side wall portion. 
      The contact area of the plurality of wavy sheets may be an area in which a trough portion of the wave shape of the wavy sheet disposed on the upper side is contacted with a crest portion of the wave shape of the wavy sheet disposed on the lower side. 
     The wavy sheet laminated body may further include a control member disposed at least either at one end side or at the other end side in the direction perpendicular to both the wave direction and the up-down direction of the wave shape of the wavy sheet laminated body and configured and adapted to control deformation of the wavy sheet. 
     The wavy sheet laminated body may further include a control member disposed at an intermediate position between one end side and the other end side in the direction perpendicular to both the wave direction and the up-down direction of the wave shape of the wavy sheet laminated body and configured and adapted to control deformation of the wavy sheet. 
     The wavy sheet laminated body, the one-end sidewall portion and the other-end sidewall portion may be formed of an elastic material. 
     The wavy sheet laminated body, the one-end sidewall portion and the other-end sidewall portion may be formed integrally with one another. 
     The wavy sheet laminated body, the one-end sidewall portion and the other-end sidewall portion may be formed by an additive manufacturing method. 
     The additive manufacturing method may be a fused-deposition-modeling type. 
     There may be provided a plate-like member having a foot sole contact surface on the upper side of the wavy sheet laminated body. 
     The wavy sheet laminated body may be composed of four or more layers of wavy sheets laminated in the up-down direction. 
     A sole for a shoe according to the present invention may include the above-mentioned shock-absorbing structure for the sole. The shock-absorbing structure for the sole may be disposed at least either at a sole heel region or at a sole forefoot region. 
     A sole for a shoe according to the present invention may include the above-mentioned shock-absorbing structure for the sole. The shock-absorbing structure for the sole may extend from a sole heel region through a sole midfoot region to a sole forefoot region. 
     As above-mentioned, according to the present invention, the above-mentioned shock-absorbing structure can improve cushioning properties and resilience and enhance durability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the invention, reference should be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention. 
         FIG.  1    is a general bottom perspective medial-side view of a shoe (for a right foot) employing a shock-absorbing structure for a sole according to a first embodiment of the present invention. 
         FIG.  2    is a medial side view of the shock-absorbing structure for the sole of  FIG.  1   . 
         FIG.  3    is a side view illustrating a general structural schematic view of the shock-absorbing structure for the sole of  FIG.  1   . 
         FIG.  4    is a general top perspective view as viewed diagonally forward of the shock-absorbing structure for the sole of  FIG.  3   . 
         FIG.  5    illustrates the state of the shock-absorbing structure for the sole of  FIG.  3    before loading or after unloading, showing an example of the three-layered wavy sheets. 
         FIG.  6    illustrates the state of the shock-absorbing structure for the sole of  FIG.  5    during loading. 
         FIG.  7    illustrates the state of the shock-absorbing structure for the sole of  FIG.  3    before loading or after unloading, showing an example in which the wavy sheets are three-layered and the one-end sidewall is an inclined wall. 
         FIG.  8    illustrates the state of the shock-absorbing structure for the sole of  FIG.  7    during loading. 
         FIG.  9    is a general bottom perspective medial-side view of a shoe (for a right foot) employing a shock-absorbing structure for a sole according to a second embodiment of the present invention. 
         FIG.  10    is a medial side view of the shock-absorbing structure for the sole of  FIG.  9   . 
         FIG.  11    is a general bottom perspective medial-side view of a shoe (for a right foot) employing a shock-absorbing structure for a sole according to a third embodiment of the present invention. 
         FIG.  11 A  is a schematic top plan view illustrating a schematic structure of the shock-absorbing structure for the sole of  FIG.  11   . 
         FIG.  11 B  is a top plan schematic view showing a first variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 C  is a top plan schematic view showing a second variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 D  is a top plan schematic view showing a third variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 E  is a top plan schematic view showing a fourth variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 F  is a top plan schematic view showing a fifth variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 G  is a top plan schematic view showing a sixth variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 H  is a top plan schematic view showing a seventh variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 I  is a top plan schematic view showing an eighth variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  11 J  is a top plan schematic view showing a ninth variation of the shock-absorbing structure for the sole of  FIG.  11 A . 
         FIG.  12    is a general bottom perspective medial-side view of a shock-absorbing structure for a sole according to a fourth embodiment of the present invention. 
         FIG.  13    is a general bottom perspective medial-side view of a wavy sheet laminated body constituting a shock-absorbing structure for a sole according to a fifth embodiment of the present invention. 
         FIG.  14    is a general top perspective medial-side view of a wavy sheet laminated body constituting a shock-absorbing structure for a sole according to a sixth embodiment of the present invention. 
         FIG.  15    is a general bottom perspective view of the wavy sheet laminated body of  FIG.  14   . 
         FIG.  16    is a side view illustrating a general structure of the wavy sheet laminated body constituting a shock-absorbing structure for a sole according to a seventh embodiment of the present invention 
         FIG.  17    is a general bottom perspective medial-side view of a shock-absorbing structure for a sole according to an eighth embodiment of the present invention. 
         FIG.  18    is a heel rear face view of the shock-absorbing structure of  FIG.  17   . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in detail with reference to embodiments thereof as illustrated in the accompanying drawings. 
     First Embodiment 
     Referring to the drawings,  FIGS.  1  to  8    show a shock-absorbing structure for a sole according to a first embodiment of the present invention. Here, a running shoe is taken for an example as a shoe. In the following explanations, “upward (upper-side/top/upper)” and “downward (lower-side/bottom/lower)” designate an upward direction and a downward direction, respectively, i.e. vertical direction of the shoe, “forward (front side/front/anterior)” and “rearward (rear side/rear/posterior)” designate a forward direction and a rearward direction, respectively, i.e. longitudinal direction of the shoe, and “a width or lateral direction” designates a crosswise direction or transverse direction of the sole. For example, as shown in  FIG.  2    (a medial side view of the shock-absorbing structure), when the state in which a sole bottom surface of the shoe is placed on the horizontal plane is taken as an example, “upward” and “downward” generally designate “upward” and “downward” in  FIG.  2   , respectively, “forward” and “rearward” generally designate “to the left side” and “to the right side” in  FIG.  2   , respectively, and “a width direction” generally designates “into the page” of  FIG.  2   . In  FIG.  2   , the background is colored in gray for illustration purposes. 
     As shown in  FIGS.  1  and  2   , a shoe S includes a shock-absorbing structure  1  for a sole of the shoe S and an upper U (indicated by a dash-and-dot line) that is provided on the shock-absorbing structure  1  and that is configured and adapted to cover a foot of a shoe wearer (not shown). The shock-absorbing structure  1  includes a heel region H, a midfoot region M, and a forefoot region F that are configured and adapted to correspond to a heel portion, a midfoot portion or a plantar arch portion, and a forefoot portion of the foot, respectively. The shock-absorbing structure  1  extends laterally and longitudinally from a heel rear end to a distal end of a tiptoe. 
     The shock-absorbing structure  1  for the sole includes a wavy sheet laminated body  2  in which a plurality of wavy sheets  20  of a longitudinally extending wave shape are laminated and layered in the up-down direction, one-end sidewall portion  3  (colored in gray) provided at one end side (on the left side of  FIGS.  1  and  2   ) in a wave direction of the wave shape of the wavy sheet laminated body  2  and restraining the plurality of wavy sheets  20 , and the other-end sidewall portion  4  (colored in gray) provided at the other end side (on the right side of  FIGS.  1  and  2   ) in the wave direction of the wave shape of the wavy sheet laminated body  2  and restraining the plurality of wavy sheets  20 . 
     The wavy sheet laminated body  2  extends longitudinally from the heel rear end to the distal end of the tiptoe and also extends laterally. The wavy sheet laminated body  2  is preferably formed of the wavy sheets  20  of three or more layers, and more preferably, the wavy sheets  20  of four or more layers. In the exemplification, the wavy sheet laminated body  2  is formed of the wavy sheets  20  of four or more layers except the distal end of the tiptoe. The one-end sidewall portion  3 , in this example, is disposed below the tiptoe, extends diagonally upwardly toward the distal end of the tiptoe, and extends in the sole width direction. The other-end sidewall portion  4 , in this example, is disposed below the heel region H, extends diagonally upwardly toward the heel rear end, and extends in the sole width direction. 
     On the upper side of the wavy sheet laminated body  2 , an upper-side wall portion  5  is provided to cover the upper side of the wavy sheet laminated body  2 , and on the lower side of the wavy sheet laminated body  2 , a lower-side wall portion  6  is provided to cover the lower side of the wavy sheet laminated body  2 . The upper-side wall portion  5  is a member extending in the sole width direction and having a foot sole contact surface  5   a  that a foot sole of the shoe wearer directly contacts or indirectly contacts through an insole (a plate-like member) IS or the like. There is provided a heel counter portion HC on the upper-side wall portion  5  that gradually rises upwardly from the midfoot region M to the heel region H to support a circumference of the heel portion of the foot of the shoe wearer. The lower-side wall portion  6  is a member extending in the sole width direction and having a ground contact surface to contact the ground. There is provided an outsole OS on the ground contact surface  6  of the lower-side wall portion  6  that has a multiple of protrusions that protrude downwardly. 
     The upper-side wall portion  5  and the lower-side wall portion  6  extend longitudinally and are connected to the one-end sidewall portion  3  and the other-end sidewall portion  4 , respectively. The one-end sidewall portion  3 , the other-end sidewall portion  4 , the upper-side wall portion  5  and the lower-side wall portion  6  constitute a box-shaped structure to encompass the wavy sheet laminated body  2 .also, the one-end sidewall portion  3 , the other-end sidewall portion  4 , the upper-side wall portion  5 , the lower-side wall portion  6  and the wavy sheet laminated body  2  constitute the sole for the shoe S. The shoe S is structured by fixedly attaching a bottom portion of the upper U to the foot sole contact surface  5   a  and the heel counter portion HC through bonding and the like. In addition, the medial and lateral side end surfaces of the wavy sheet laminated body  2  may be disposed at a position to be flush with or to recede slightly inwardly relative to the medial and lateral side end surfaces of the one-end sidewall portion  3 , the other-end sidewall portion  4 , the upper-side wall portion  5  and the lower-side wall portion  6 . 
       FIGS.  3  and  4    schematically illustrate the shock-absorbing structure  1  for the sole. Here, an example is shown in which the wavy sheet laminated body  2  is formed of seven-layered wavy sheets  20   1  to  20   7  that are laminated in the up-down direction. Each of the respective wavy sheets  20   1  to  20   7  is a thin sheet-like member and has a sine-wave shape. The wavelengths and amplitudes of the respective wave shapes are equal between the wavy sheets  20   1  to  20   7 . The phases of the respective wave shapes of the wavy sheets  20   1 ,  20   3 ,  20   5  and  20   7  differ from the phases of the respective wave shapes of the wavy sheets  20   2 ,  20   4  and  20   6  by π (i.e. 180 degrees). Thereby, the trough portions t (see white dots) of the respective wave shapes of the respective wavy sheets  20   1 ,  20   3 ,  20   5  and  20   7  are in contact with the ridge portions r (see black dots) of the respective wave shapes of the respective wavy sheets  20   2 ,  20   4  and  20   6  (in  FIG.  3   , only a part of the trough portions t and the ridge portions r is shown). These contact areas are connecting portions  10  that both the wavy sheets  20   1 ,  20   3 ,  20   5 ,  20   7  and  20   2 ,  20   4 ,  20   6  are connected to one another (in  FIG.  3   , only a part of the connecting portions  10  is shown). Here, the respective connecting portions  10  are connected by integrally forming both of the wavy sheets. Also, in this exemplification, in the entire wavy sheets  20   1  to  20   7 , the trough portions t and the ridge portions r of the respective wavy shapes are connected to one another by the connecting portions  10 . On the other hand, between the ridge portions of the wave shapes of the wavy sheets disposed on the upper side and the trough portions of the wave shapes of the wavy sheets disposed on the lower side, there are formed a gap c extending in the sole width direction. Additionally, in the respective wavy sheets  20   1  to  20   7 , the ridge lines to join the ridge portions r of the wave shapes extend in the sole width direction and similarly the trough lines to join the trough portions t of the wave shapes extend in the sole width direction. 
     As the concrete numerical values of the wavelength and the amplitude of the wave shapes of the respective wavy sheets  20   1  to  20   7 , the wavelength is preferably 15 mm or less, and the amplitude is preferably 7.5 mm or less. Also, the concrete numerical values of the thickness of the respective wavy sheets  20   1  to  20   7  are preferred to be 1.5 mm or less, and more preferred to be around 1 mm. In this way, the wavy sheet laminated body  2  according to the present embodiment incorporates a laminated microwave structure in the shoe sole. 
     In  FIGS.  3  and  4   , the wave directions of the wave shapes of the respective wavy sheets  20   1  to  20   7  are left to right direction of the drawings. On one end side (i.e. left side of the drawings) of the wave directions, the one-end sidewall portion  3  is disposed, and on the other end side (i.e. right side of the drawings) of the wave directions, the other-end sidewall portion  4  is disposed. In the drawings, the one-end sidewall portion  3  and the other-end sidewall portion  4  are respectively shown as a wall portion that extend in the up-down direction. Also, in this example, for the entire wavy sheets  20   1  to  20   7 , the one-end sides of the wave directions of the wave shapes are connected to the one-end sidewall potion  3 , and the other-end sides of the wave directions of the wave shapes are connected to the other-end sidewall potion  4 . 
     The shock-absorbing structure  1  for the sole (and thus the wavy sheet laminated body  2 , the one-end sidewall portion  3  and the other-end sidewall portion  4  that form the shock-absorbing structure  1 ) is preferably formed of an elastic material and in this example integrally formed using the elastic material. As the elastic material, elastomer resin is preferable, which includes ester, urethane, styrene, amide, olefin, and the like. Also, when forming the shock-absorbing structure  1  for the sole, the upper-side wall portion  5  and the lower-side wall portion  6  are also integrated with one another. 
     The shock-absorbing structure  1  for the sole (and thus the wavy sheet laminated body  2 , the one-end sidewall portion  3  and the other-end sidewall portion  4  that form the shock-absorbing structure  1 ) is molded (or formed/3D-printed) preferably by an additive manufacturing, through a 3D printer. As such a 3D printer, FDM (Fused Deposition Modeling)-method type is preferably used. This method may utilize thermoplastic resin such as nylon, polyester, TPU (thermos-plastic polyurethane), PU (polyurethane), thermoplastic elastomer and the like, or rubber and the like. A soft material is preferable and the soft material having an Asker A hardness of 90 A or below is more preferable. 
     When molding the shock-absorbing structure  1  for the sole by the 3D printer, the upper-side wall portion  5  and the lower-side wall portion  6  as well are simultaneously molded (or 3D-printed) by the 3D printer. That can eliminate a working process for disposing and fixedly attaching the wavy sheet laminated body  2  in a space encompassed by the box-shaped structure composed of the one-end sidewall portion  3 , the other-end sidewall portion  4 , the upper-side wall portion  5  and the lower-side wall portion  6 , thus reducing a cost. Also, when molding the shock-absorbing structure  1  for the sole by the 3D printer, the heel counter portion CH and the outsole OS as well are simultaneously molded (or 3D-printed) by the 3D printer. In such a fashion, the sole for the shoe can be molded at one time by the 3D printer, the manufacturing process can be simplified and the manufacturing cost can be further reduced. Although this is not shown in the figure, during molding by the 3D printer, there may be provided above the upper-side wall portion  5  a three-dimensional resin filament structure in which a multiple of resin filaments are arranged in various directions including up-down and left-right directions. Such a resin filament structure includes a three-dimensional special filament structure such as a laminate network, a three-dimensional network and the like, which can display a good elasticity in not only front-rear, left-right and up-down directions but also every direction. In this case, the upper surface of the resin filament structure or the upper surface of an insole forms the foot sole contact surface. 
      Then, the function effect of the above-mentioned embodiment will be explained using  FIGS.  5  to  8   . In  FIGS.  5  to  8   , an example is shown in which the wavy sheet laminated body  2  of the shock-absorbing structure  1  for the sole is composed of three-layered wavy sheets  20   1  to  20   3 . In  FIGS.  5  and  6   , an example is shown in which the one-end sidewall portion  3  is a vertically extending wall portion, and in  FIGS.  7  and  8   , an example is shown in which the one-end sidewall portion  3  is a diagonally upwardly extending wall portion. Also,  FIGS.  5  and  7    show the state before loading or after unloading (that is, the state in which load is not acted), and  FIGS.  6  and  8    show the state after loading. 
     From the state of unloading the shock-absorbing structure  1  for the sole as shown in  FIG.  5   , as a load is applied in the up-down direction at the time of landing, the shock-absorbing structure  1  for the sole deforms as shown in  FIG.  6   . 
     At this juncture, the load imparted to the wavy sheet  20   1  acts to the wavy sheet  20   2  through the contact area of the wavy sheet  20   1  with the wavy sheet  20   2 , and then to the wavy sheet  20   3  through the contact area of the wavy sheet  20   2  with the wavy sheet  20   3 . Thereby, during loading, the respective wavy sheets  20   1  to  20   3  laminated in the up-down direction disperse the load and compressive-deform in the up-down direction thus absorbing the load effectively to improve cushioning properties. 
     Moreover, in this case, since there are provided the one-end sidewall portion  3  and the other-end sidewall portion  4  at the one end side and the other end side respectively in the wave direction of the respective wavy sheets  20   1  to  20   3  to restrain the one end side and the other end side of the respective wavy sheets  20   1  to  20   3 , when the respective wavy sheets  20   1  to  20   3  compressive-deform during loading, an elongation to the one end side and the other end side in the wave direction of the respective wavy sheets  20   1  to  20   3  is restrained. Thereby, during the compressive-deformation of the respective wavy sheets  20   1  to  20   3 , the amplitude of the wave shape (i.e. a vertical height in  FIG.  6   ) of the respective wavy sheets  20   1  to  20   3  is hard to become zero, such that thereby the respective wavy sheets  20   1  to  20   3  can accumulate an elastic energy in an efficient way. As a result of this, the accumulated elastic energy can be released after unloading to improve resilience. In such a fashion, since the deformation amount during deformation of the shock-absorbing structure  1  for the sole can be lessened, not only the bending rigidity of the shock-absorbing structure  1  can be enhanced but also the torsional rigidity thereof can be enhanced. 
     Furthermore, since the respective wavy sheets  20   1  to  20   3  laminated in the up-down direction are interconnected to one another through the connecting portions  10  formed of contact areas between the adjacent wavy sheets  20   1  to  20   3 , not through a member different from the wavy sheets  20   1  to  20   3 , durability of the whole shock-absorbing structure  1  for the sole can be improved. Also, in this case, during compressive-deformation of the respective wavy sheets  20   1  to  20   3 , since the wave shapes of the respective wavy sheets  20   1  to  20   3  move to a flattened shape compared to the shape before the compressive-deformation, the contact areas between the adjacent respective wavy sheets  20   1  to  20   3  are enlarged, thereby preventing a separation of the wavy sheets  20   1  to  20   3  at the contact areas between the adjacent respective wavy sheet  20   1  to  20   3  thus further enhancing durability. 
     Next, in the case as well in which the one-end sidewall portion  3  is an inclined wall portion extending diagonally, from the state of unloading the shock-absorbing structure  1  for the sole as shown in  FIG.  7   , as a load is applied in the up-down direction at the time of landing, the shock-absorbing structure  1  for the sole deforms as shown in  FIG.  8   . 
     At this juncture, the load imparted to the wavy sheet  20   1  acts to the wavy sheet  20   2  through the contact area of the wavy sheet  20   1  with the wavy sheet  20   2 , and then to the wavy sheet  20   3  through the contact area of the wavy sheet  20   2  with the wavy sheet  20   3 . Thereby, during loading, the respective wavy sheets  20   1  to  20   3  laminated in the up-down direction disperse the load and compressive-deform in the up-down direction thus absorbing the load effectively to improve cushioning properties. In this case, because the one-end sidewall portion  3  is an inclined wall and thus the number of the wave shapes differs between the respective wavy sheets  20   1  to  20   3 , cushioning properties can be adjusted. 
     Moreover, in this case, since there are provided the one-end sidewall portion  3  and the other-end sidewall portion  4  at the one end side and the other end side respectively in the wave direction of the respective wavy sheets  20   1  to  20   3  to restrain the one end side and the other end side of the respective wavy sheets  20   1  to  20   3 , when the respective wavy sheets  20   1  to  20   3  compressive-deform during loading, an elongation to the one end side and the other end side in the wave direction of the respective wavy sheets  20   1  to  20   3  is restrained. Thereby, during the compressive-deformation of the respective wavy sheets  20   1  to  20   3 , the amplitude of the wave shape (i.e. a vertical height in  FIG.  8   ) of the respective wavy sheets  20   1  to  20   3  is hard to become zero, such that thereby the respective wavy sheets  20   1  to  20   3  can accumulate an elastic energy in an efficient way. As a result of this, the accumulated elastic energy can be released after unloading thus improving resilience. Also, in this case, because the one-end sidewall portion  3  is an inclined wall and thus the number of the wave shapes differs between the respective wavy sheets  20   1  to  20   3 , resilience can be adjusted. 
     Furthermore, since the respective wavy sheets  20   1  to  20   3  laminated in the up-down direction are interconnected to one another through the connecting portions  10  formed of contact areas between the adjacent wavy sheets  20   1  to  20   3 , not through a member different from the wavy sheets  20   1  to  20   3 , durability of the whole shock-absorbing structure  1  for the sole can be improved. 
     Also, in the first embodiment, since the shock-absorbing structure  1  for the sole extends from the heel region H through the midfoot region M to the forefoot region F of the sole, from heel-in to toe-off during running, when the load is transferred from the heel region H through the midfoot region M to the forefoot region F, cushioning properties and resilience of the respective regions can be improved and durability can be enhanced. Also, the shock-absorbing structure  1  for the sole is adaptable not only to a heel striker who lands on the ground from the heel but also a forefoot striker who lands on the ground from the forefoot region and a midfoot striker who lands on the ground from the midfoot region. 
     As the inclination of the one-end sidewall portion  3 , it is not limited to that shown in  FIGS.  7  and  8   . Any direction is acceptable except the direction perpendicular to the up-down direction (that is, the longitudinal direction). Also, the inclined wall portion may be provided at the other-end sidewall portion  4 , alternatively, both at the one-end sidewall portion  3  and at the other-end sidewall portion  4  (see  FIGS.  1  and  2   ). 
     Second Embodiment 
       FIGS.  9  and  10    show a shock-absorbing structure for a sole according to a second embodiment of the present invention. In the drawings, like reference numbers indicate identical or functionally similar elements. In  FIG.  10   , the background is colored in gray for illustration purposes. 
     In the above-mentioned first embodiment, an example was shown in which the shock-absorbing structure for the sole includes the heel region H, the midfoot region M and the forefoot region F and extends longitudinally from the heel rear end of the heel region H through the midfoot region M to the distal end of the tiptoe of the forefoot region F, but in this second embodiment the shock-absorbing structure for the sole is provided at the heel region H and the forefoot region F, not at the midfoot region M, and thus separated longitudinally. 
     As shown in  FIGS.  9  and  10   , the shock-absorbing structure for the sole according to the second embodiment includes a shock-absorbing structure  1   1  disposed at the heel region H and a shock-absorbing structure  1   2  disposed at the forefoot region F. 
     The shock-absorbing structure  1   1  comprises a wavy sheet laminated body  2   1  in which a plurality of wavy sheets  20  of a longitudinally extending wave shape are laminated in the up-down direction, one-end sidewall portion  3   1  (colored in gray) provided at one end side in the wave direction of the wave shape of the wavy sheet laminated body  2   1  and restraining the plurality of wavy sheets  20 , and the other-end sidewall portion  4   1  (colored in gray) provided at the other end side in the wave direction of the wave shape of the wavy sheet laminated body  2   1  and restraining the plurality of wavy sheets  20 . The wavy sheet laminated body  2   1  extends longitudinally from the heel rear end of the heel region H to the rear end of the midfoot region M and also extends in the sole width direction. In this exemplification, the one-end sidewall portion  3   1  is disposed below the rear end of the midfoot region M and formed in a curved shaped. The other-end sidewall portion  4   1  is disposed below the heel region H and extends diagonally upwardly toward the heel rear end. 
     On the upper side of the wavy sheet laminated body  2   1 , an upper-side wall portion  5   1  is provided to cover the upper side of the wavy sheet laminated body  2   1 , and on the lower side of the wavy sheet laminated body  2   1 , a lower-side wall portion  6   1  is provided to cover the lower side of the wavy sheet laminated body  2   1 . The upper-side wall portion  5   1  is a member extending in the sole width direction and having a foot sole contact surface  5   a  that a foot sole of the shoe wearer directly contacts or indirectly contacts through an insole (a platelike member) IS or the like. There is provided a heel counter portion HC on the upper-side wall portion  5   1  that gradually rises upwardly from the midfoot region M to the heel region H to support a circumference of the heel portion of the foot of the shoe wearer. The lower-side wall portion  6   1  is a member extending in the sole width direction and having a ground contact surface to contact the ground. There is provided an outsole OS on the ground contact surface of the lower-side wall portion  6   1  that has a multiple of protrusions that protrude downwardly. 
     The upper-side wall portion  5   1  and the lower-side wall portion  6   1  extend longitudinally and are connected to the one-end sidewall portion  3   1  and the other-end sidewall portion  4   1 , respectively. The one-end sidewall portion  3   1 , the other-end sidewall portion  4   1 , the upper-side wall portion  5   1  and the lower-side wall portion  6   1  constitute a box-shaped structure to encompass the wavy sheet laminated body  2   1 . Also, the one-end sidewall portion  3   1 , the other-end sidewall portion  4   1 , the upper-side wall portion  5   1 , the lower-side wall portion  6   1  and the wavy sheet laminated body  2   1  constitute the sole for the heel region H of the shoe. 
     The shock-absorbing structure  1   2  comprises a wavy sheet laminated body  2   2  in which a plurality of wavy sheets  20  of a longitudinally extending wave shape are laminated in the up-down direction, one-end sidewall portion  3   2  (colored in gray) provided at one end side in the wave direction of the wave shape of the wavy sheet laminated body  2   2  and restraining the plurality of wavy sheets  20 , and the other-end sidewall portion  4   2  (colored in gray) provided at the other end side in the wave direction of the wave shape of the wavy sheet laminated body  2   2  and restraining the plurality of wavy sheets  20 . The wavy sheet laminated body  2   2  extends longitudinally from the front end of the midfoot region M to the distal end of the tiptoe of the forefoot region F and also extends in the sole width direction. In this exemplification, the one-end sidewall portion  3   2  is disposed below the tiptoe and extends diagonally upwardly toward the tiptoe. The other-end sidewall portion  4   2  is disposed below the front end of the midfoot region M and formed in a curved shaped. 
     On the upper side of the wavy sheet laminated body  2   2 , an upper-side wall portion  5   2  is provided to cover the upper side of the wavy sheet laminated body  2   2 , and on the lower side of the wavy sheet laminated body  2   2 , a lower-side wall portion  6   2  is provided to cover the lower side of the wavy sheet laminated body  2   2 . The upper-side wall portion  5   2  is a member extending in the sole width direction and having a foot sole contact surface  5   a  that a foot sole of the shoe wearer directly contacts or indirectly contacts through an insole (a platelike member) IS or the like. The lower-side wall portion  6   2  is a member extending in the sole width direction and having a ground contact surface to contact the ground. There is provided an outsole OS on the ground contact surface of the lower-side wall portion  6   2  that comprises a multiple of protrusions that protrude downwardly. 
     The upper-side wall portion  5   2  and the lower-side wall portion  6   2  extend longitudinally and are connected to the one-end sidewall portion  3   2  and the other-end sidewall portion  4   2 , respectively. The one-end sidewall portion  3   2 , the other-end sidewall portion  4   2 , the upper-side wall portion  5   2  and the lower-side wall portion  6   2  constitute a box-shaped structure to encompass the wavy sheet laminated body  2   2 . Also, the one-end sidewall portion  3   2 , the other-end sidewall portion  4   2 , the upper-side wall portion  5   2 , the lower-side wall portion  6   2  and the wavy sheet laminated body  2   2  constitute the sole for the forefoot region F of the shoe. 
     In the shock-absorbing structure  1   1 , the one end side in the wave direction of the wave shapes of the wavy sheets of the wavy sheet laminated body  2   1  is connected to the one-end sidewall portion  3   1 , and the other end side in the wave direction of the wave shapes of the wavy sheets of the wavy sheet laminated body  2   1  is connected to the other-end sidewall portion  4   1 . Likewise, in the shock-absorbing structure  1   2 , the one end side in the wave direction of the wave shapes of the wavy sheets of the wavy sheet laminated body  2   2  is connected to the one-end sidewall portion  3   2 , and the other end side in the wave direction of the wave shapes of the wavy sheets of the wavy sheet laminated body  2   2  is connected to the other-end sidewall portion  4   2 . Also, the upper and lower sides of the wavy sheet laminated body  2   1  are connected to the upper-side wall portion  5   1  and the lower-side wall portion  6   1  respectively and the upper and lower sides of the wavy sheet laminated body  2   2  are connected to the upper-side wall portion  5   2  and the lower-side wall portion  6   2  respectively. 
     The shock-absorbing structure  1   1  for the sole (and thus the wavy sheet laminated body  2   1 , the one-end sidewall portion  3   1  and the other-end sidewall portion  4   1  that form the shock-absorbing structure  1   1 ) is preferably integrated with one another using an elastic material such as elastomer resin and the like. The shock-absorbing structure  1   1  for the sole is more preferably molded (or formed/3D-printed) by additive manufacturing, preferably through a 3D printer. As such a 3D printer, FDM (Fused Deposition Modeling)-method type is preferably used. During forming of the shock-absorbing structure  1   1  for the sole, the upper-side wall portion  5   1  and the lower-side wall portion  6   1  are also integrated with one another. 
     Similarly, the shock-absorbing structure  1   2  for the sole (and thus the wavy sheet laminated body  2   2 , the one-end sidewall portion  3   2  and the other-end sidewall portion  4   2  that form the shock-absorbing structure  1   2 ) is preferably integrated with one another using an elastic material such as elastomer resin and the like. The shock-absorbing structure  1   2  for the sole is more preferably molded (or formed/3D-printed) by additive manufacturing, preferably through a 3D printer of FDM-method type. During forming of the shock-absorbing structure  1   2  for the sole, the upper-side wall portion  5   2  and the lower-side wall portion  6   2  are also integrated with one another. 
     Also, during forming the shock-absorbing structures  1   1  and  1   2  for the sole, the midfoot region M disposed between the shock-absorbing structures  1   1  and  1   2  is also integrally formed. That can eliminate a working process for disposing and fixedly attaching the wavy sheet laminated body  2   1  in a space encompassed by the one-end sidewall portion  3   1 , the other-end sidewall portion  4   1 , the upper-side wall portion  5   1  and the lower-side wall portion  6   1 , and also eliminate a working process for disposing and fixedly attaching the wavy sheet laminated body  2   2  in a space encompassed by the one-end sidewall portion  3   2 , the other-end sidewall portion  4   2 , the upper-side wall portion  5   2  and the lower-side wall portion  6   2 . In addition, the shoe sole can be manufactured at one time by the 3D printer. Thereby, a manufacturing process can be simplified and a manufacturing cost can be further reduced. 
     The second embodiment as well displays a similar function effect to that of the above-mentioned first embodiment. 
     When a load is applied in the up-down direction at the time of a heel strike onto the ground, the load imparted to the upper-side wavy sheet  20  of the wavy sheet laminated body  2   1  of the shock-absorbing structures  1   1  acts to the lower-side wavy sheet  20  through the contact area of the upper-side wavy sheet  20  with the lower-side wavy sheet  20 , and then to the further lower-side wavy sheet  20  through the contact area to the still further lower-side wavy sheet  20 . Thereby, during loading, the respective wavy sheets  20  laminated in the up-down direction disperse the load and compressive-deform in the up-down direction thus absorbing the load effectively to improve cushioning properties of the heel region H. In this case, because the one-end sidewall portion  3   1  is a curved wall, the other-end sidewall portion  4   1  is an inclined wall, and thus the number of the wave shapes differs between the respective wavy sheets  20  laminated in the up-down direction, cushioning properties of the heel region H can be adjusted. 
     Moreover, in this case, since there are provided the one-end sidewall portion  3   1  and the other-end sidewall portion  4   1  at the one end side and the other end side respectively in the wave direction of the respective wavy sheets  20  to restrain the one end side and the other end side of the respective wavy sheets  20 , when the respective wavy sheets  20  compressive-deform during loading, an elongation to the one end side and the other end side in the wave direction of the respective wavy sheets  20  is restrained. Thereby, during the compressive-deformation of the respective wavy sheets  20 , the amplitude of the wave shape of the respective wavy sheets  20  is hard to become zero, such that thereby the respective wavy sheets  20  can accumulate an elastic energy in an efficient way. As a result of this, the accumulated elastic energy can be released after unloading to improve resilience of the heel region H. In such a fashion, not only the bending rigidity of the heel region H of the shock-absorbing structure  1  can be enhanced but also the torsional rigidity thereof can be enhanced. In this case, because the one-end sidewall portion  3   1  is a curved wall, the other-end sidewall portion  4   1  is an inclined wall, and thus the number of the wave shapes differs between the respective wavy sheets  20  laminated in the up-down direction, cushioning properties of the heel region H can be adjusted. 
     Furthermore, since the respective wavy sheets  20  laminated in the up-down direction are interconnected to one another through the contact areas between the adjacent wavy sheets  20 , not through a member different from the wavy sheets  20 , durability of the whole shock-absorbing structure  1  for the sole can be improved. Also, in this case, during compressive-deformation of the respective wavy sheets  20 , since the wave shapes of the respective wavy sheets  20  move to a flattened shape compared to the shape before the compressive-deformation, the contact areas between the adjacent respective wavy sheets  20  are enlarged, thereby preventing a separation of the wavy sheets  20  at the contact areas between the adjacent respective wavy sheets  20  thus further enhancing durability. 
     On the other hand, when a load is applied in the up-down direction at the time of a forefoot strike onto the ground, the load imparted to the upper-side wavy sheet  20  of the wavy sheet laminated body  2   2  of the shock-absorbing structure  1   2  acts to the lower-side wavy sheet  20  through the contact area of the upper-side wavy sheet  20  with the lower-side wavy sheet  20 , and then to the further lower-side wavy sheet  20  through the contact area to the still further lower-side wavy sheet  20 . Thereby, during loading, the respective wavy sheets  20  laminated in the up-down direction disperse the load and compressive-deform in the up-down direction thus absorbing the load effectively to improve cushioning properties of the forefoot region F. In this case, because the one-end sidewall portion  3   2  is an inclined wall, the other-end sidewall portion  4   2  is a curved wall, and thus the number of the wave shapes differs between the respective wavy sheets  20  laminated in the up-down direction, cushioning properties of the forefoot region F can be adjusted. 
     Moreover, in this case, since there are provided the one-end sidewall portion  3   2  and the other-end sidewall portion  4   2  at the one-end side and the other-end side respectively in the wave direction of the respective wavy sheets  20  to restrain the one-end side and the other-end side of the respective wavy sheets  20 , when the respective wavy sheets  20  compressive-deform during loading, an elongation to the one-end side and the other-end side in the wave direction of the respective wavy sheets  20  is restrained. Thereby, during the compressive-deformation of the respective wavy sheets  20 , the amplitude of the wave shape of the respective wavy sheets  20  is hard to become zero, such that thereby the respective wavy sheets  20  can accumulate an elastic energy in an efficient way. As a result, the accumulated elastic energy can be released after unloading thus improving resilience of the forefoot region F. In such a fashion, not only the bending rigidity of the forefoot region F of the shock-absorbing structure  1   2  can be improved but also the torsional rigidity thereof can be enhanced. In this case, because the one-end sidewall portion  3   2  is a curved wall, the other-end sidewall portion  4   2  is an inclined wall, and thus the number of the wave shapes differs between the respective wavy sheets  20  laminated in the up-down direction, cushioning properties of the forefoot region F can be adjusted. 
     Furthermore, since the respective wavy sheets  20  laminated in the up-down direction are interconnected to one another through the contact areas between the adjacent wavy sheets  20 , not through a member different from the wavy sheets  20 , durability of the whole shock-absorbing structure for the sole can be improved. Also, in this case, during compressive-deformation of the respective wavy sheets  20 , since the wave shapes of the respective wavy sheets  20  move to a flattened shape compared to the shape before the compressive-deformation, the contact areas between the adjacent respective wavy sheets  20  are enlarged, thereby preventing a separation of the wavy sheets  20  at the contact areas between the adjacent respective wavy sheets  20  thus further enhancing durability. 
     Third Embodiment 
       FIG.  11    shows a shock-absorbing structure for a sole according to a third embodiment of the present invention. In the drawing, like reference numbers indicate identical or functionally similar elements. 
     The third embodiment differs from the second embodiment in that sinusoidal wave shaped portions  21 ,  22  are provided on the both sides (that is, medial and lateral sides) of the wavy sheet laminated body  2   1  of the shock-absorbing structure  1   1  for the sole of the second embodiment (In  FIG.  11   , only the medial side is shown). The sinusoidal wave shaped portions  21 ,  22  may be provided at either the medial side or the lateral side of the wavy sheet laminated body  2   1 . Also, the sinusoidal wave shaped portions  21 ,  22  may be provided at either one or both of the medial side and the lateral side of the wavy sheet laminated body  2   2 . Moreover, the sinusoidal wave shaped portions  21 ,  22  may be provided at either one or both of the medial side and the lateral side of the wavy sheet laminated bodies  2   1  and  2   2 . 
     The respective sinusoidal wave shaped portions  21 ,  22  have a wave shape of a greater wavelength and amplitude compared to the wavy sheet  20  and the phase of the wave shaped portion  22  is offset by π (i.e. 180 degrees) relative to the phase of the wave shaped portion  21 . Also, in this example, the thickness of the respective wave shaped portions  21 ,  22  is greater than that of the wavy sheet  20 . The respective wave shaped portions  21 ,  22  are coupled to the medial and lateral side end portions of the wavy sheet  20 . The one end side and the other end side of the respective wave shaped portions  21 ,  22  in the wave direction are connected to the one-end sidewall portion  3   1  and the other-end sidewall portion  4   1  respectively. 
     In this case, because the respective wave shaped portions  21 ,  22  can restrain deformation of the respective wavy sheets  20 , the respective wave shaped portions  21 ,  22  can control the degree of deformation of the respective wavy sheets  20  according to material, thickness, shape and the like of the respective wave shaped portions  21 ,  22 , and can function as a control member to control the hardness (or softness) of the shock-absorbing structure for the sole itself. In addition, only one of the wave shaped portions  21 ,  22  may be provided. Alternatively, another wave shaped portion in addition to the wave shaped portions  21 ,  22  may be provided. 
     Here, the variations of dispositions and extending directions of the respective wave shaped portions  21 ,  22  relative to the respective wavy sheets  20  will be explained using  FIGS.  11 A to  11 J . These drawings are top plan schematic views that schematically show the respective wavy sheet  20  and the respective wavy shaped portions  21 ,  22 . In the drawings, the respective wavy shaped portions  21 ,  22  are shown in a dash-and-dot line for illustration purposes. 
     In a first variation shown in  FIG.  11 A , the respective wavy shaped portions  21 ,  22  extend along the entire sole width direction (i.e. to the left-right direction in  FIG.  11 A ) crossing the wavy sheet  20  and also extend from the outside position of the medial side end through the wavy sheet  20  in the sole width direction to the outside position of the lateral side end. The respective wavy shaped portions  21 ,  22  extend longitudinally from the rear end to the front end of the wavy sheet  20 . 
     The medial and lateral side end surfaces of the respective wave shaped portions  21 ,  22  are for example flush with the medial and lateral side end surfaces of the one-end sidewall portion  3   1 , the other-end sidewall portion  4   1 , the upper-side wall portion  5   1  and the lower-side wall portion  6   1  ( FIG.  11   ), and alternatively disposed at a slightly outwardly protruding position (or inwardly receding position) relative to the medial and lateral side end surfaces of the one-end sidewall portion  3   1 , the other-end sidewall portion  4   1 , the upper-side wall portion  5   1  and the lower-side wall portion  6   1 . 
     In a second variation shown in  FIG.  11 B , the respective wave shaped portions  21 ,  22  extend in the sole width direction from the outside position of the medial side end of the wavey sheet  20  to the position beyond the laterally central portion (that is, the inside position of the lateral side end) and extend longitudinally from the rear end to the front end of the wavy sheet  20 . 
     In a third variation shown in  FIG.  11 C , the respective wave shaped portions  21 ,  22  extend in the sole width direction from the outside position of the lateral side end of the wavey sheet  20  to the position beyond the laterally central portion (that is, the inside position of the medial side end) and extend longitudinally from the rear end to the front end of the wavy sheet  20 . 
     In a fourth variation shown in  FIG.  11 D , the respective wavy shaped portions  21 ,  22  extend along the entire sole width direction (i.e. to the left-right direction in  FIG.  11 D ) from the outside position of the medial side end to the outside position of the lateral side end. The respective wavy shaped portions  21 ,  22  extend longitudinally from the rear end to the position beyond the longitudinally central portion of the wavy sheet  20 . 
     In a fifth variation shown in  FIG.  11 E , the respective wavy shaped portions  21 ,  22  extend along the entire sole width direction (i.e. to the left-right direction in  FIG.  11 E ) from the outside position of the medial side end to the outside position of the lateral side end. The respective wavy shaped portions  21 ,  22  extend longitudinally from the front end to the position beyond the longitudinally central portion of the wavy sheet  20 . 
     In a sixth variation shown in  FIG.  11 F , the respective wavy shaped portions  21 ,  22  extend in the sole width direction from the inside position of the medial side end to the inside position of the lateral side end, and also extend longitudinally from the rear end to the front end of the wavy sheet  20 . 
     In a seventh variation shown in  FIG.  11 G , the respective wave shaped portions  21 ,  22  extend in the sole width direction from the inside position of the medial side end of the wave shaped portion  20  to the position beyond the laterally central portion (that is, the inside position of the lateral side end) and extend longitudinally from the rear end to the front end of the wavy sheet  20 . 
     In an eighth variation shown in  FIG.  11 H , the respective wave shaped portions  21 ,  22  extend in the sole width direction from the inside position of the lateral side end of the wave shaped portion  20  to the position beyond the laterally central portion (that is, the inside position of the medial side end) and extend longitudinally from the rear end to the front end of the wavy sheet  20 . 
     In a ninth variation shown in  FIG.  11 I , the respective wavy shaped portions  21 ,  22  extend in the sole width direction from the inside position of the medial side end to the inside position of the lateral side end of the wavy sheet  20  and extend longitudinally from the rear end to the position beyond the longitudinally central portion of the wavy sheet  20 . 
     In a tenth variation shown in  FIG.  11 J , the respective wavy shaped portions  21 ,  22  extend in the sole width direction from the inside position of the medial side end to the inside position of the lateral side end of the wavy sheet  20  and extend longitudinally from the front end to the position beyond the longitudinally central portion of the wavy sheet  20 . 
     Fourth Embodiment 
       FIG.  12    shows a shock-absorbing structure for a sole according to a fourth embodiment of the present invention. In the drawing, like reference numbers indicate identical or functionally similar elements. 
     The fourth embodiment differs from the above-mentioned second embodiment in that slant lattice-shaped portions  21 ′,  22 ′ are provided on the both sides (that is, medial and lateral sides) of the wavy sheet laminated body  2   1  of the shock-absorbing structure  1   1  of the sole according to the second embodiment (in  FIG.  12   , only the medial side is shown). The slant lattice-shaped portions  21 ′,  22 ′ may be provided at either the medial side or the lateral side of the wavy sheet laminated body  2   1 . Also, the slant lattice-shaped portions  21 ′,  22 ′ may be provided at either one or both of the medial side and the lateral side of the wavy sheet laminated body  2   2 . Moreover, the slant lattice-shaped portions  21 ′,  22 ′ may be provided at either one or both of the medial sides and the lateral sides of the wavy sheet laminated bodies  2   1  and  2   2 . 
     The thickness of the respective slant lattice-shaped portions  21 ′,  22 ′ is greater than that of the wavy sheet  20 . The respective slant lattice-shaped portions  21 ′,  22 ′ are coupled to the medial and lateral side end portions of the wavy sheet  20 . The front and rear ends of the respective slant lattice-shaped portions  21 ′,  22 ′ are connected to the one-end sidewall portion  3   1  and the other-end sidewall portion  4   1  respectively. 
     In this case, because the respective slant lattice-shaped portions  21 ′,  22 ′ can restrain the deformation of the respective wavy sheets  20 , the respective slant lattice-shaped portions  21 ′,  22 ′ can control the degree of deformation of the respective wavy sheets  20  according to material, thickness, shape and the like of the respective slant lattice-shaped portions  21 ′,  22 ′, and can function as a control member to control the hardness (or softness) of the shock-absorbing structure for the sole itself. In addition, only one of the slant lattice-shaped portions  21 ′,  22 ′ may be provided. Alternatively, another slant lattice-shaped portion in addition to the slant lattice-shaped portions  21 ′,  22 ′ may be provided. 
     The medial and lateral side end surfaces of the respective slant lattice-shaped portions  21 ′,  22 ′ are for example flush with the medial and lateral side end surfaces of the one-end sidewall portion  3   1 , the other-end sidewall portion  4   1 , the upper-side wall portion  5   1  and the lower-side wall portion  6   1 , and alternatively disposed at a slightly outwardly protruding position (or a slightly inwardly receding position) relative to the medial and lateral side end surfaces of the one-end sidewall portion  3   1 , the other-end sidewall portion  4   1 , the upper-side wall portion  5   1  and the lower-side wall portion  6   1 . 
     Here, the variations of dispositions and extending directions of the respective slant lattice-shaped portions  21 ′,  22 ′ relative to the respective wavy sheets  20  are similar to those of the respective wavy shaped portions  21 ,  22  (see  FIGS.  11 A to  11 J ). Accordingly, the respective slant lattice-shaped portions  21 ′,  22 ′ may extend along the entire sole width from the medial side end to the lateral side end of the respective wave sheets  20 . Also, either one or both of the medial and lateral ends of the respective slant lattice-shaped portions  21 ′,  22 ′ may be disposed at a position inside the medial side end and/or lateral side end of the respective wavy sheets  20 . The respective slant lattice-shaped portions  21 ′,  22 ′ may extend longitudinally from the rear end to the front end. Also, either one or both of the front and rear ends may be disposed at a position inside the front end and/or rear end of the respective wavy sheets  20 . 
     Fifth Embodiment 
       FIG.  13    shows a wavy sheet laminated body constituting a shock-absorbing structure for a sole according to a fifth embodiment of the present invention. In the drawing, like reference numbers indicate identical or functionally similar elements. 
     In the above-mentioned first embodiment, an example was shown in which the shock-absorbing structure  1  for the sole is structured by integrally forming the wavy sheet laminated body  2 , the one-end sidewall portion  3  and the other-end sidewall portion  4 . In the fifth embodiment, the wavy sheet laminated body  2  is formed separately from the one-end sidewall portion  3  and the other-end sidewall portion  4 . In this case, the one-end sidewall portion  3 , the other-end sidewall portion  4 , the upper-side wall portion  5  and the lower-side wall portion  6  of the shock-absorbing structure  1  for the sole are integrally formed with one another in a separate process, the wavy sheet laminated body  2  is inserted into a space encompassed by the one-end sidewall portion  3 , the other-end sidewall portion  4 , the upper-side wall portion  5  and the lower-side wall portion  6  and fixedly attached to the respective wall portions by bonding and the like. Alternatively, the wavy sheet laminated body  2  is formed in advance and then used as an insert to perform an insert molding when forming the one-end sidewall portion  3 , the other-end sidewall portion  4 , the upper-side wall portion  5  and the lower-side wall portion  6  of the shock-absorbing structure  1  for the sole. 
     In addition, when forming the upper-side wall portion  5  by the 3D printer, there may be provided above the upper-side wall portion  5  a resin filament structure composed of a multiple of resin filaments extending in the up-down direction and the left-right direction. Such a resin filament structure has a three-dimensional filament structure and can exhibit a good elasticity in every direction including the front-rear, left-right and up-down directions. In this case, the upper surface of the resin filament structure or an insole forms a foot sole contact surface. In addition, the wavy sheet laminated body  2  formed separately from the one-end sidewall portion  3  and the other-end sidewall portion  4  may be disposed at least either at the heel region H or at the forefoot region F. 
     Sixth Embodiment 
       FIGS.  14  and  15    show a wavy sheet laminated body constituting a shock-absorbing structure for a sole according to a sixth embodiment of the present invention. In the drawings, like reference numbers indicate identical or functionally similar elements. 
     As shown in  FIGS.  14  and  15   , in the sixth embodiment, there are a number of through holes  20   a  extending in the up-down direction and formed at the respective wavy sheets  20  of the wavy sheet laminated body  2 . In the illustrated example, the through holes  20   a  are formed and perforated at the midfoot region M and the forefoot region F, but they may be formed and perforated at the heel region H. Alternatively, the through holes  20   a  may be formed and perforated at the entire regions. The perforated areas and positions are arbitrary. Perforating such through holes  20   a  causes the rigidity of the wavy sheet  20  to be decreased, cushioning properties to be improved, and the weight of the wavy sheet laminated body  2  to be reduced. In addition, the respective through holes  20   a  do not need to be aligned in the up-down direction. Also, all the wavy sheets  20  laminated in the up-down direction do not need to be perforated. For example, every other wavy sheet  20  may be perforated. 
     Seventh Embodiment 
       FIG.  16    schematically shows a wavy sheet laminated body constituting a shock-absorbing structure for a sole according to a seventh embodiment of the present invention. In the drawing, like reference numbers indicate identical or functionally similar elements. 
     In the above-mentioned first embodiment, an example was shown in which the wavy sheet laminated body  2  composed of a plurality of vertically laminated wavy sheets  20  is formed integrally with one another. In the seventh embodiment, the respective wavy sheets  20  are formed respectively in a separate process and thereafter the wavy sheets  20  may be fixedly attached to one another via bonding or the like. In the illustrated example shown in  FIG.  16   , the respective wavy sheets  20   3  to  20   7  are bonded to one another at the connecting portion  10 . At the respective connecting portions  10 , similar to the above-mentioned first embodiment, the trough portion t of the wavy sheet disposed on the upper side and the ridge portion r of the wavy sheet disposed on the lower side are positioned and bonded. In the example shown in  FIG.  16   , the respective wavy sheets  20   1 ,  20   2  are going to be bonded in a similar procedure. 
     Additionally, all of the wavy sheets to compose the wavy sheet laminated body  2  may not be bonded. For example, after the wavy sheets  20   3  to  20   7  have been integrally formed, the wavy sheets  20   1 ,  20   2  formed in a separate step may be bonded to the wavy sheet  20   3 . 
     Eighth Embodiment 
       FIGS.  17  and  18    show a shock-absorbing structure for a sole according to an eighth embodiment of the present invention. In the drawings, like reference numbers indicate identical or functionally similar elements. 
      In the above-mentioned first and second embodiments, an example was shown in which the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) to compose the wavy sheet laminated body  2  (or  2   1  and  2   2 ) are disposed in such a way that the wave directions of the wave shapes of the respective wavy sheets  20  extend in the longitudinal direction, that is, the ridge lines and the trough lines of the wave shapes are disposed in the sole width direction, but the application of the present invention is not restricted to such an example. 
     As shown in  FIG.  18   , in the eighth embodiment, the wave directions of the wave shapes of the respective wavy sheets  20  composing the wavy sheet laminated body  2   1  of the heel region H extend in the lateral direction (or the sole width direction), that is, the ridge lines and the trough lines of the wave shapes are disposed in the longitudinal direction. The wave directions of the wave shapes of the respective wavy sheets  20  composing the wavy sheet laminated body  2   2  of the forefoot region F as well extend in the lateral direction (or the sole width direction), that is, the ridge lines and the trough lines of the wave shapes are disposed in the longitudinal direction. In both of the heel region H and the forefoot region F, the respective wavy sheets  20  laminated in the up-down direction are interconnected to one another at respective contact areas. 
     In the heel region H, at the one end side in the wave direction of the wave shapes of the respective wavy sheets  20  of the wavy sheet laminated body  2   1 , the one-end sidewall portion  7   1  is disposed, and at the other end side in the wave direction of the wave shapes of the respective wavy sheets  20  of the wavy sheet laminated body  2   1 , the other-end sidewall portion  7   2  is disposed. The one end side of the wave direction of the respective wavy sheets  20  is connected to and restrained at the one-end sidewall portion  7   1 , and the other end side of the wave direction of the respective wavy sheets  20  is connected to and restrained at the other-end sidewall portion  7   2 . Likewise, in the forefoot region F, at the one end side in the wave direction of the wave shapes of the respective wavy sheets  20  of the wavy sheet laminated body  2   2 , the one-end sidewall portion  8   1  is disposed, and at the other end side in the wave direction of the wave shapes of the respective wavy sheets  20  of the wavy sheet laminated body  2   2 , the other-end sidewall portion (not shown) is disposed. The one end side of the wave direction of the respective wavy sheets  20  is connected to and restrained at the one-end sidewall portion  8   1 , and the other end side of the wave direction of the respective wavy sheets  20  is connected to and restrained at the other-end sidewall portion (not shown). 
     The eighth embodiment as well displays a similar function effect to those of the above-mentioned first and second embodiments. 
     When a load is applied in the up-down direction at the time of a heel strike onto the ground, the load imparted to the upper side wavy sheet  20  of the wavy sheet laminated body  2   1  of the shock-absorbing structure  1   1  acts to the lower side wavy sheet  20  through the contact area of the upper side wavy sheet  20  with the lower side wavy sheet  20 , and then to the further lower side wavy sheet  20  through the contact area to the still further lower side wavy sheet  20 . Thereby, during loading, the respective wavy sheets  20  laminated in the up-down direction disperse the load and compressive-deform in the up-down direction thus absorbing the load effectively to improve cushioning properties of the heel region H. 
      Moreover, in this case, since there are provided the one-end sidewall portion  7   1  and the other-end sidewall portion  7   2  at the one end side and the other end side respectively in the wave direction of the respective wavy sheets  20  to restrain the one end side and the other end side of the respective wavy sheets  20 , when the respective wavy sheets  20  compressive-deform during loading, an elongation to the one end side and the other end side in the wave direction of the respective wavy sheets  20  is restrained. Thereby, during the compressive-deformation of the respective wavy sheets  20 , the amplitude of the wave shape of the respective wavy sheets  20  is hard to become zero, such that thereby the respective wavy sheets  20  can accumulate an elastic energy in an efficient way. As a result, the accumulated elastic energy can be released after unloading thus improving resilience of the heel region H. In such a manner, not only the bending rigidity of the heel region H of the shock-absorbing structure  1  can be enhanced but also the torsional rigidity thereof can be enhanced. 
     Furthermore, since the respective wavy sheets  20  laminated in the up-down direction are interconnected to one another through the contact areas between the adjacent wavy sheets  20 , not through a member different from the wavy sheets  20 , durability of the whole shock-absorbing structure  1  for the sole can be improved. Also, in this case, during compressive-deformation of the respective wavy sheets  20 , since the wave shapes of the respective wavy sheets  20  move to a flattened shape compared to the shape before the compressive-deformation, the contact areas between the adjacent respective wavy sheets  20  are enlarged, thereby preventing a separation of the wavy sheets  20  at the contact areas between the adjacent respective wavy sheets  20  thus further enhancing durability. 
     On the other hand, when a load is applied in the up-down direction at the time of a forefoot strike onto the ground, the load imparted to the upper side wavy sheet  20  of the wavy sheet laminated body  2   2  of the shock-absorbing structure  1   2  acts to the lower side wavy sheet  20  through the contact area of the upper side wavy sheet  20  with the lower side wavy sheet  20 , and then to the further lower side wavy sheet  20  through the contact area to the still further lower side wavy sheet  20 . Thereby, during loading, the respective wavy sheets  20  laminated in the up-down direction disperse the load and compressive-deform in the up-down direction thus absorbing the load effectively to improve cushioning properties of the forefoot region F. 
     Moreover, in this case, since there are provided the one-end sidewall portion  8   1  and the other-end sidewall portion (not shown) at the one end side and the other end side respectively in the wave direction of the respective wavy sheets  20  to restrain the one end side and the other end side of the respective wavy sheets  20 , when the respective wavy sheets  20  compressive-deform during loading, an elongation to the one end side and the other end side in the wave direction of the respective wavy sheets  20  is restrained. Thereby, during the compressive-deformation of the respective wavy sheets  20 , the amplitude of the wave shape of the respective wavy sheets  20  is hard to become zero, such that thereby the respective wavy sheets  20  can accumulate an elastic energy in an efficient way. As a result, the accumulated elastic energy can be released after unloading thus improving resilience of the forefoot region F. In such a manner, not only the bending rigidity of the forefoot region F of the shock-absorbing structure  1   2  can be improved but also the torsional rigidity thereof can be enhanced. 
     Furthermore, since the respective wavy sheets  20  laminated in the up-down direction are interconnected to one another through the contact areas between the adjacent wavy sheets  20 , not through a member different from the wavy sheets  20 , durability of the whole shock-absorbing structure for the sole can be improved. Also, in this case, during compressive-deformation of the respective wavy sheets  20 , since the wave shapes of the respective wavy sheets  20  move to a flattened shape compared to the shape before the compressive-deformation, the contact areas between the adjacent respective wavy sheets  20  are enlarged, thereby preventing a separation of the wavy sheets  20  at the contact areas between the adjacent respective wavy sheets  20  thus further enhancing durability. 
     First Variation 
     In the above-mentioned first to eighth embodiments, an example was shown in which the one-end sidewall portion  3  (or  3   1 ,  3   2  and  7   1 ) couples and restrains all the wavy sheets  20  at the one end side in the wavy direction of the wavy sheet laminated body  2  (or  2   1  and  2   2 ), but it may be at least one (e.g. at least two layers) of the wavy sheets  20  that is coupled and restrained to the one-end sidewall portion  3  (or  3   1 ,  3   2  and  7   1 ). Similarly, in the first to eighth embodiments, an example was shown in which the other-end sidewall portion  4  (or  4   1 ,  4   2  and  7   2 ) couples and restrains all the wavy sheets  20  at the other end side in the wavy direction of the wavy sheet laminated body  2  (or  2   1  and  2   2 ), but it may be at least one (e.g. at least two layers) of the wavy sheets  20  that is coupled and restrained to the other-end sidewall portion  4  (or  4   1 ,  4   2  and  7   2 ). 
     Also, the one-end sidewall portion  3  (or  3   1 ,  3   2  and  7   1 ) may be disposed with a gap relative to the one end in the wave direction of the wavy sheet laminated body  2  (or  2   1  and  2   2 ). In the same manner, the other-end sidewall portion  4  (or  4   1 ,  4   2  and  7   2 ) may be disposed with a gap relative to the other end in the wave direction of the wavy sheet laminated body  2  (or  2   1  and  2   2 ). In these cases, when loading, the wavy sheet laminated body  2  (or  2   1  and  2   2 ) can elongate the extent of the gap toward the one end side and the other end side in the wave direction. When the one end and the other end in the wave direction of the wave shapes come into contact with the one-end sidewall portion  3  (or  3   1 ,  3   2  and  7   1 ) and the other-end sidewall portion  4  (or  4   1 ,  4   2  and  7   2 ), an elongation of the wavy sheet laminated body  2  (or  2   1  and  2   2 ) is restricted and restrained. 
     Second Variation 
     In the above-mentioned first to eighth embodiments, an example was shown in which all of the contact areas of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) laminated in the up-down direction in the wavy sheet laminated body  2  (or  2   1  and  2   2 ) are interconnected to one another through the connecting portions  10 , but the application of the present invention is not restricted to such an example. The portions connected by the connecting portions  10  may be a part of all the contact areas of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ). 
     Third Variation 
     In the above-mentioned first to eighth embodiments, an example was shown in which the contact areas of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) are the areas of contact of the wave-shaped troughs t of the wavy sheets disposed on the upper side with the wave-shaped ridges r of the wavy sheets disposed on the lower side, the contact areas of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) are not limited to such an example. The respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) may be contacted with one another at intermediate areas between the wave-shaped troughs t and the wave-shaped ridges r. 
     Fourth Variation 
     In the above-mentioned first to eighth embodiments, an example was shown in which the wave shapes of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) are sinusoidal and the wavelengths, amplitudes and thicknesses of the wavy shapes are the same in all of the wavy sheet  20  (or  20   1  to  20   7  and  20   1  to  20   3 ), but the wavelengths, amplitudes and thicknesses of the wavy shapes may be different according to the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ), or partially different in the longitudinal/lateral direction in the same wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ). Also, the phase shift of the wave shapes of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) laminated in the up-down direction is not limited to π (i.e. 180 degrees) shown in the first to eighth embodiments. 
     Fifth Variation 
     In the above-mentioned first to eighth embodiments, an example was shown in which the wave shapes of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) are sinusoidal, but the wave shapes of the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) are not limited to such an example. Other optional appropriate wave shapes such as a rectangular wave, triangular wave, saw wave, trapezoidal wave and the like may be adopted. Also, a plurality of waves of different shapes can be combined. 
     Sixth Variation 
     In the above-mentioned first to seventh embodiments, an example was shown in which the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) extend continuously along the entire sole width direction, but the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) may be separated in the sole width direction. For example, the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) may be disposed at the medial side region and the lateral side region respectively and separated at a central region between the medial side region and the lateral side region. 
     Also, in the above-mentioned eighth embodiment, an example was shown in which the respective wavy sheets  20  extend continuously in the longitudinal direction in the heel region H and the forefoot region F, but the respective wavy sheets  20  may be separated in the longitudinal direction. For example, the respective wavy sheets  20  may be disposed at the heel rear region and the heel front region respectively and separated at the heel central region. The respective wavy sheets  20  may be disposed at the forefoot rear region and the forefoot front region respectively and separated at the forefoot central region. 
      In the first to seventh embodiments, an example was shown in which the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) are visible from the medial and lateral sides, but the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) may not be visible from the medial and lateral sides by covering the medial and lateral sides of the shock-absorbing structures  1 ,  1   1  and  1   2 . Alternatively, the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) may not be visible from the medial and lateral sides by incorporating the respective wavy sheets  20  (or  20   1  to  20   7  and  20   1  to  20   3 ) inside the sole. 
     Seventh Variation 
     In the above-mentioned second embodiment, an example was shown in which the shock-absorbing structure for the sole is disposed at both the heel region H and the forefoot region F, but the application of the current invention is not restricted to such an example. The shock-absorbing structure for the sole may be disposed only at either the heel region H or the forefoot region F. 
     Other Application 
     In the above-mentioned respective embodiments and alternative embodiments, an example was shown in which the shock-absorbing structure according to the present invention was applied to a running shoe, but the application of the present invention is not restricted to such an example. The present invention also has application to various sports shoes including walking shoes, other shoes including sandals. 
     As mentioned above, the present invention is useful for a shock-absorbing structure for a sole that can improve cushioning properties and resilience, and that can enhance durability. 
     Those skilled in the art to which the invention pertains may make modifications and other embodiments employing the principles of this invention without departing from its spirit or essential characteristics particularly upon considering the foregoing teachings. The described embodiments and examples are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. Consequently, while the invention has been described with reference to particular embodiments and examples, modifications of structure, sequence, materials and the like would be apparent to those skilled in the art, yet fall within the scope of the invention.