Patent Application
20080034615
The present invention relates to a shock absorbing device of a shoe sole.
The cushioning function of absorbing and alleviating the shock at landing is demanded in shoe soles, in addition to the lightness in weight and the function of supporting the foot stably. Recently, shoe soles having the repulsion function (rebound function) in addition to the above-mentioned functions have been presented. The repulsion function refers to the function of storing the impact energy at landing as deformation energy and emitting the energy of deformation when disengaging from the ground. This function is useful for improving exercise ability of a wearer.
By compressing or bending an element of the shoe sole, the deformation energy is stored in the element. However, when viscoelastic material having a small Young's modulus such as foamed resin used for a cushioning member of the shoe sole is deformed, energy is dissipated as heat and so on. Accordingly, generally, such viscoelastic material cannot perform the repulsion function sufficiently.
The configurations of shoes having the above-mentioned repulsion function are disclosed in the following patent documents.
First patent document: Japanese Utility Model Registration No. 3082722
Second patent document: Japanese Utility Model Registration No. 3053446
Third patent document: Japanese Patent Laid Open No. 02-114905
Fourth patent document: Japanese Patent Laid Open No. 01-274705
Fifth patent document: Japanese Patent Laid Open No. 2004-065978
Sixth patent document: Japanese Utility Model Registration No. 3093214
Seventh patent document: WO96/38062 (Japanese National Phase PCT Laid Open Publication of No. 11-506027)
The first and second patent documents disclose shoes with an improved repulsion function. In the first and second patent documents, the repulsion function is improved by attaching a repulsive member, which is obtained by forming an elastic material in the shape of a tube, to a bottom surface of the shoe sole. However, since such repulsive members have substantially the same size as the foot and supports the whole of the foot with a curved surface, it cannot support the foot stably.
However, this spring 101 is accommodated in the soft midsole 100. Accordingly, most part of impact energy (shock energy) at landing is absorbed and dissipated in the midsole 100, and the remainder of the energy is absorbed by the spring 101. Accordingly, the amount of energy stored by the spring 101 is reduced.
In addition, impact load (shock force) of landing is applied to the oval spring 101 after having been dispersed in the midsole 100. Accordingly, since the dispersed impact load is applied on each part of the oval spring 101 as distributed load, the amount of deflection of the endless spring 101 is considered to be small. Therefore, impact energy cannot be stored in the oval spring 101 sufficiently.
Since the reaction plate 104 is accommodated in the shoe sole also in the shoe disclosed in this patent document, the shoe has similar demerits to the shoe of the third patent document. It is supposed that the part, in which deformation energy due to shock at landing is stored, is mainly the fore and rear curved parts 104b, 104b, not the upper and lower facing sides 104a, 104a.
The shoe sole of the fifth patent document has a plurality of honeycomb deforming members 106. When the shoe sole is compressed vertically, the deforming members 106 deform from the state shown in
In this figure, a depressed part 121 is formed at a part of the midsole 120 corresponding to the heel, and a cushioning member 121 made of plastic is disposed to the depressed part 121. The cushioning member 122 is formed to be tubular in the shape of a letter “D” from the side view. A circular-arc arch part 123 and a flat bottom plate part 124 integrally constitute the cushion member 122. A venting cavity 125 is formed between the arch part 123 and the flat plate part 124.
In this shoe, the bottom plate part 124 of the cushion member 122 is flat-shaped. Accordingly, even if the shock at landing is applied to the shoe sole from below, the bottom plate part 124 does not perform bending deformation.
As shown in the figure, a cavity 131 is formed in an insole body 130. A plate 132 and an insert 133 are accommodated in the cavity 131. The insert 133 has a V-shaped part consisting of a heel lever 134, a fulcrum 135 and a base 136. During heel strike, localized shock force is applied to a heel region 137, thereby to enhance the energy return characteristics of the insert 133.
In this prior art, since the heel region 137 corresponding to the V-shaped part of the insert 133 protrudes downwards, shock force is easy to be absorbed by the insert 133.
However, since the insert 133 is V-shaped, when a load F1 is applied obliquely from below the shoe at an initial landing of the foot, the base 136 is easy to be compressed in the longitudinal direction of the plate and to buckle. Accordingly, in the case where the load F1 is applied obliquely from below the shoe, the base 136 is hard to perform bending deformation. Further, bending deformation does not occur in a part of the heel lever 134 forward of the fulcrum 135. That is, the part of the heel lever 134 cannot absorb shock or store energy.
Moreover, with the configuration shown in this figure, in the foot-flat stance where the whole of the foot touches the ground, the insert 133 bends, thereby to return stored energy. However, in the period during which the initial landing is shifted to the foot-flat stance, energy cannot be stored sufficiently and therefore cannot be returned sufficiently.
Therefore, an object of the present invention is to provide a shock absorbing device for a shoe sole performing a high cushioning function and repulsion function by absorbing and storing the impact load of landing sufficiently.
A shock absorbing device for a shoe sole according to the present invention comprises: an outer sole having a ground contact surface that contacts the ground at landing and an upper surface opposite to the ground contact surface; a midsole that is disposed above the outer sole and has a bottom surface; and a deformation element disposed between the outer sole and the midsole. The deformation element is joined to the bottom surface of the midsole and is joined to the upper surface of the outer sole. The deformation element has a tubular part in a flat tubular form. Young's modulus of a material constituting the tubular part is greater than both that of a material constituting the midsole and that of a material constituting the outer sole. The tubular part is arranged so as to have a major axis generally along a longitudinal direction of a foot and a minor axis generally along a vertical direction. A length of the major axis is set within a range of about 25 mm to about 80 mm. The tubular part has a lower portion that is curved so as to be convex downwards and thereby undergoes bending deformation due to an impact load of landing. A concave first curved surface is provided on the upper surface of the outer sole, and the lower portion of the tubular part fits into the first curved surface of the outer sole.
In a shock absorbing device for a shoe sole according to the present invention, an external force applied to the outer sole is directly transmitted to the tubular part having a great Young's modulus before being absorbed by the soft midsole. Accordingly, since the tubular part can absorb much of the external force, the tubular part performs a high repulsion function by leaf spring (flat spring) structure. In addition, the tubular part, the outer sole and the midsole integrally deforms, thereby to perform a high cushioning function.
Especially, since the lower portion of the tubular part is curved so as to be convex downwards, the lower portion performs large bending deformation due to the impact load of landing. Accordingly, the lower portion can easily store repulsion energy and perform a high cushioning function.
Furthermore, since the length of the major axis (major diameter) of the tubular part is set within a range of about 25 mm to about 80 mm, the tubular part is expected to perform sufficient bending deformation, and is able to support the foot stably. That is, when the length of the major axis of the tubular part is less than 25 mm, the tubular part is too small to perform bending deformation; when the length of the major axis is more than 80 mm, the tubular part is too large to maintain the stability. In view of this, it is preferred that the length of the major axis of the tubular part be set within a range of about 35 mm to 55 mm.
In the present invention, by the use of the term “the deformation element is joined to the bottom surface of the midsole”it is meant to include, for example, the case where the deformation element is joined directly to the midsole and the case where the deformation element is indirectly joined to the midsole via another member, which is located between the deformation element and the midsole and retains the deformation element.
By the use of the term “the deformation element is joined to the upper surface of the outer sole”, it is meant to include the case where a bottom surface of the deformation element is joined directly to the upper surface of the outer sole, and the case where another member to improve the adhesiveness between the deformation element and the outer sole is interposed therebetween.
According to a preferred aspect of the present invention, the tubular part has an upper portion that is curved so as to be convex upwards and thereby undergoes bending deformation due to the impact load of landing, a concave second curved surface is provided on the bottom surface of the midsole, and the upper portion of the tubular part fits into the second curved surface of the midsole.
In this aspect, since the upper portion of the tubular part is curved, both ends of the upper portion can be displaced in the direction of the major axis. Accordingly, the lower portion of the tubular part becomes easier to deform. In addition, the upper portion of the tubular part also becomes easier to perform bending deformation. Accordingly, the function of absorbing and storing the impact energy at landing on the ground becomes higher.
According to another preferred aspect of the present invention, a third curved surface that is curved so as to be convex downwards generally along the lower portion of the tubular part is provided on the ground contact surface of the outer sole.
In this aspect, since the ground contact surface is curved, the bending deformation of the lower portion is immediately caused due to the shock applied to a part of the ground contact surface of the outer sole at the moment of landing, i.e., at the time of the first strike. Accordingly, the impact energy of landing can be absorbed and stored in approximately the whole of the lower portion of the tubular part. In addition, since the curved outer sole deforms at the same time, the outer sole can also absorb and store the impact energy.
Since the outer sole is curved, the outer sole need not be formed unnecessarily thick, thereby to decrease the weight of the shoe sole. Furthermore, the outer sole becomes of such a shape that the outer sole may land sequentially from its rear end to its front while a wearer takes the landing action, i.e., a heel part of the foot lands and then the fore foot part gradually lands on the ground. Accordingly, a smooth motion of the foot during the period from landing on the ground to disengaging from the ground can be realized.
According to another preferred aspect of the present invention, the tubular part is disposed at a rear foot part of the midsole, and at least a part of the lower portion of the tubular part protrudes (bulges) downwards further than the rear foot part of the midsole.
In this aspect, since the lower portion of the tubular part protrudes downwards, the part of the outer sole below the tubular part firstly lands on the ground in the above-mentioned landing action. Accordingly, a great impact load at the moment of the landing (at the time of the first strike) is absorbed and stored in the deformation element. In view of this, it is preferred that substantially whole of the lower portion of the tubular part protrude (bulge) downwards further than the rear foot part of the midsole.
According to another preferred aspect of the present invention, the deformation element is provided at least on a lateral side of a rear foot part of the foot.
Generally, at landing, the lateral side of the rear foot part of the foot firstly lands on the ground, and therefore, by providing the deformation element on the lateral side of the rear foot part of the foot, the impact load of landing can be more sufficiently absorbed.
In this aspect, it is preferred that at least two deformation elements be provided separately from each other in a medial-lateral direction of the foot. Such constitution is useful for weight saving of the shoe.
In the case where deformation elements at the rear foot part of the foot are provided separately from each other in the medial-lateral direction (widthwise direction) of the foot, it is preferred the rigidity of the deformation element on the medial side be set greater than that of the deformation element on the lateral side, for example, by making their Young's modulus or thickness different from each other.
In addition, it is more preferred that at least two deformation elements be provided on the lateral side of the rear foot part of the foot. In such constitution, deformation elements of appropriate size can be arranged on the lateral side of the foot, thereby to absorb the shock and perform the high repulsion function in substantially the whole of the lateral side of the rear foot part where the shock of landing is applied.
In the case where deformation elements are provided separately from each other in the medial-lateral direction of the foot, it is preferred the minor axis of the tubular part becomes shorter as it gets closer to a center in the medial-lateral direction of the foot. The major axis may be of the similar shape.
In such constitution, since the diameter of the tubular part varies, it becomes possible to remove a mold or a die at the time of molding the tubular part. Furthermore, by forming the minor axis of the tubular part in the center in the medial-lateral direction shorter than that in the medial edge and lateral edge, it is possible to prevent the center of the shoe sole from protruding further than the medial side and the lateral side of the shoe sole, thereby to improve the stability of the foot in a stationary state.
According to another preferred aspect of the present invention, a shock absorbing member having a smaller Young's modulus than the tubular part is provided in an internal space of the tubular part.
If the shock is absorbed only in the tubular part, too much localized stress may be induced in a part of the tubular part. Accordingly, by providing the cushioning member other than the tubular part in the internal space of the tubular part, a burden to the tubular part can be reduced.
In addition, by providing the cushioning member having a smaller Young's than the tubular part in the internal space of the tubular part, it becomes possible to apply various combination of the tubular part having the repulsion function and the cushioning member having the cushioning function. It enables more appropriate design of the deformation element, taking into consideration the characteristics of repulsion, cushioning, endurance and so on.
In the present invention, it is preferred that the Young's modulus of the material constituting the tubular part be set within a range of about 1 kgf/mm2 to about 30 kgf/mm2.
This is because when the Young's modulus of the material constituting the tubular part is less than 1 kgf/mm2, the material is so soft that the energy cannot be stored in the curved lower portion of the tubular part; when the Young's modulus of the material constituting the tubular part is more than 30 kgf/mm2, the rigidity of the lower portion is so large that deflection of the lower portion is too small and that the lower portion cannot store the energy sufficiently.
According to another preferred aspect of the present invention, the tubular part has a front end portion in front of the lower portion and a rear end portion in the rear of the lower portion, and external surfaces of the two end portions are covered with the midsole and/or the outer sole.
Every time the lower portion of the tubular part undergoes bending deformation, a great stress is induced at the end portions of the tubular part. Accordingly, the end portions need great endurance. By covering such end portions with the midsole and/or the outer sole, aging deterioration of the end portions by light or the like can be prevented, thereby to improve the endurance of the end portions.
According to another preferred aspect of the present invention, the tubular part has a front end portion in front of the lower portion and a rear end portion in the rear of the lower portion, and a thickness of the end portion is greater than both that of the upper portion and that of the lower portion. By thickening the two end portions, which are subjected to great load due to the bending deformation, it becomes possible to improve more the endurance of the end portions.
In this aspect, for example, the thickness of the end portions is set within a range of about 1.5 mm to about 8.0 mm, and the thickness of the upper portion and the thickness of the lower portion are each set within a range of about 1.0 mm to about 4.0 mm.
According to another preferred aspect of the present invention, a connecting member having a greater Young's modulus than the midsole is joined to the bottom surface of the midsole, the tubular part is joined to the connecting member, and by joining the tubular part to the connecting member, the deformation element is retained by the connecting member.
Thus, by locating the connecting member above the deformation element, which member has a greater Young's modulus, and joining the deformation element to this connecting member, the adhesiveness of the deformation element is improved. That is, the deformation element becomes less likely to drop off. Furthermore, since the connecting member having a greater Young's modulus retains the deformation element, the deformation element becomes less likely to be displaced.
According to another preferred aspect of the present invention, the tubular part is integrally formed to be a single seamless member which is seamless in a longitudinal section of the shoe sole.
According to another preferred aspect of the present invention, a length of the minor axis of the tubular part is set within a range of about 8 mm to about 25 mm, and flatness obtained by dividing the length of the major axis by the length of the minor axis of the tubular part is set within a range of about 1.5 to about 4.0.
If the length of the minor axis of the tubular part is less than about 8 mm, the lower portion cannot have sufficiently large curvature, and so cannot absorb the shock sufficiently by bending deformation. If the minor diameter is more than 25 mm, too large deformation is caused, and so the foot cannot be supported stably, i.e., the stability of the foot is impaired.
FIGS. 6(a) to 6(c) are partial sectional views showing an example of the shoe sole of the present invention, and FIGS. 6(d) to 6(f) are partial sectional views showing an example of the shoe sole that is not included in the present invention.
FIGS. 7(a) to 7(e) are partial sectional views showing modifications of the shoe sole of the present invention.
FIGS. 8(a) to 8(e) are perspective views showing modifications of a tubular part.
FIGS. 9(a) to 9(i) show modifications of the tubular part, FIGS. 9(a), 9(b), 9(c) and 9(i) are sectional views along the medial-lateral direction of the foot, and FIGS. 9(d) to 9(h) are sectional views along the longitudinal direction of the foot.
FIGS. 10(a) to 10(h) are sectional views showing modifications of the cushioning member.
FIGS. 11(a) to 11(e) are schematic side views showing behavior of a body from landing on the ground to disengaging from the ground during running.
FIGS. 12(a) to 12(e) are partial lateral side views showing deformation of a rear foot part of the shoe sole according to the first embodiment during landing.
FIGS. 13(a) to 13(d) are partial medial sectional views showing the deformation of the rear foot part of the shoe sole.
FIGS. 14(a) and 14(b) each show a conventional shoe,
FIGS. 15(a) to 15(c) each show a conventional shoe sole,
FIGS. 16(a) and 16(b) each show a conventional shoe,
FIGS. 19(a) and 19(b) are exploded perspective views of the cushioning member.
The present invention will be understood more apparently from the following description of preferred embodiment when taken in conjunction with the accompanying drawings. However, it will be appreciated that the embodiments and the drawings are given for the purpose of mere illustration and explanation and should not be utilized to define the scope of the present invention. The scope of the present invention is to be defined only by the appended claims. In the drawings annexed, the same reference numerals denote the same or corresponding parts throughout several views.
Embodiments of the present invention will now be described with reference to the drawings.
FIGS. 1 to 4 show a first embodiment of the present invention.
As shown in
As shown in
As shown in
The second outer sole 2B are divided into the medial side and the lateral side, and the medial and lateral sides of the second outer soles 2B are spaced apart from each other in the medial-lateral direction. Each side of the second outer soles 2B is arranged so as to cover, from below, the two deformation elements 3, 3 aligned along the longitudinal direction Y on the respective side.
As shown in
Deformation Element 3:
As shown in
Young's modulus of the cushioning member 35 is smaller than that of the tubular part 30. A material forming the cushioning member 35 may be, for example, a rubber-like or pod-like compression deformation member.
The “rubber-like or pod-like compression deformation member” means a member that deforms so as to store a force of restitution (repulsion) while being compressed, and includes not only a member having rubber elasticity such as thermoplastic elastomer and vulcanized rubber but also a pod-like or bladder-like member in which air, a gelatinous material, a soft rubber-like elastic material or the like is filled. The “thermoplastic elastomer” means a polymer material that exhibits a property of vulcanized rubber at normal temperature and gets plasticized at high temperature to be molded with a plastic processing machine.
In the present invention, the rubber-like member, i.e., the member having rubber elasticity, means a member that is capable of great deformation (for example, rupture elongation thereof is more than 100%) and that is capable of recovering its original shape after the stress σ (sigma) is removed. In this member, as shown in a solid line L1 of the stress-strain diagram of
Accordingly, generally, as shown in a broken line L2 of the
As shown in
Note that the “elastic limit” means a maximum stress in the range where the relationship between the change of the compression load applied to the compression deformation member and the change of the amount of the compression of this member is proportional, i.e., where the change of the strain is proportional to the change of the compression stress.
In the present invention, “Young's modulus” means a ratio of the stress to the strain in the beginning PI of the deformation of the material, as shown in
The rubber-like member may be formed of rubber or rubber-like synthetic resin (thermoplastic elastomer). In the case where the rubber-like member is formed of rubber-like synthetic resin, for example, gel (commercial name for the cushioning member), a material of the rubber-like member may be, for example, polyurethane gel or styrene gel. The rubber-like member may be formed of resin form of EVA etc., instead of the gel or in addition to the gel.
Instead of the rubber-like member, a member that deforms so as to store a force of restitution (repulsion) while being compressed, such as a pod-like member in which air or liquid is filled, may be used.
Since load is concentrated on the deformation element 3, great stress is generated therein. Therefore, it is preferred that the elastic limit of the cushioning member 35 is larger than that of the midsole M. It makes the cushioning member 35 less likely to be subjected to permanent deformation even if the shoe is worn over and over again.
In a case where a material forming the cushioning member 35 is gel, it is preferred that Young's modulus of the gel is about 0.1 kgf/mm2 to about 1.0 kgf/mm2.
The tubular part 30 is formed of a material having Young's modulus greater than Young's modulus of the material forming the midsole M and Young's modulus of the material forming the outer sole 2. The Young's modulus of the material forming the tubular part 30 is about 1.0 kgf/mm2 to about 30 kgf/mm2, and, more preferably, it is about 2.0 kgf/mm2 to about 10 kgf/mm2. The material forming the tubular part 30 may be, for example, non-foam resin such as nylon, polyurethane and FRP.
Young's modulus of the materials forming the tubular part 30 and the cushioning member 35 may differ from the medial side of the rear foot part to the lateral side of the rear foot part. A thickness of the tubular part 30 and a section area of plane section of the cushioning member 35 may differ from the medial side of the rear foot part to the lateral side of the rear foot part. Such setting makes a vertical compressive stiffness per unit area of the deformation element 3 on the lateral side of the rear foot part more than that of the deformation element 3 on the medial side of the rear foot part, thereby preventing an excessive pronation of the foot.
As shown in
The length of the major axis Lr is set within a range of about 25 mm to about 80 mm. The length of the minor axis Sr is set within a range of about 8 mm to about 25 mm. Note that the length of the minor axis Sr means the height of the deformation element. Flatness (Lr/Sr) obtained by dividing the length of the major axis Lr by the length of the minor axis Sr of the tubular part is set within a range of about 1.5 to about 4.0.
As shown in
As shown in
It is preferred that in the vicinity of the end portion (the front end and the rear end) of the major axis Lr, the thickness of the tubular part 30 gradually decreases as it gets closer to the end portions, and the thickness of the tubular part 30 at the end portion of the major axis Lr is set approximately twice to five times as large as that at end portions (the upper end and the rear end) of the minor axis.
Because of such settings, when the impact load of landing is applied, the tubular part 30 will substantially not undergo deformation at the end portions of the major axis Lr and will undergo bending deformation at the end portions of the minor axis Sr. Moreover, since the thickness of the tubular part 30 does not change abruptly in the vicinity of the end portions of the major axis Lr, the end portions become less likely to be subjected to stress concentration, thereby greatly improving the endurance of the tubular part 30.
Connecting Member 4:
As shown in
Accordingly, the upper portion 32 of the tubular part 30 fits into the second curved surface 12 of the second midsole body 1B via the connecting member 4.
As shown in
Young's modulus of the connecting member 4 is set larger than that of the midsole M. Since the connecting member 4 having such large Young's modulus retains the tubular part 30, the midsole M becomes less likely to suffer a high localized load at the time of landing and a part of the midsole M where the tubular part 30 is joined is less likely to be damaged, as compared to a case where the tubular part 30 is directly joined to the midsole M.
As shown in
Second Outer Sole 2B:
As shown in
As shown in
In the rear foot part of the foot, an area of the bottom surface of the midsole body 1B divided by an area of the bottom surface of the second outer sole 2B is 1.3 or more. That is, an area of the bottom surface of a part of the midsole M in the rear of the arch divided by the area of the bottom surface of the second outer sole 2B is 1.3 or more.
As shown in
Since the end portions 33 of the tubular part 30 are covered with another member, the end portions 33, which is subjected to large load every time the tubular part 30 undergoes the bending deformation, can be protected from the strength reduction due to aging deterioration of by light and the like, the endurance of the end portions.
Deformation of the shoe sole during the period from landing on the ground to disengaging from the ground:
Next, a test on deformation of the shoe sole in the case where the user, wearing the shoe sole of the first embodiment, makes a series of motions from landing on the ground to disengaging from the ground will be described. In this test, the Young's modulus of the tubular part 30 was set at 5 kgf/mm2. A gel was used as the shock absorbing member, and the Young's modulus of a gel 35 on the medial side of the foot and that of a gel 35 on the lateral side of the foot were set at 0.2 kgf/mm2 and 0.3 kgf/mm2, respectively.
First, a motion of the foot during running will be described. FIGS. 11(a) to 11(e) are schematic side views showing a series of motions of a body from landing on the ground to disengaging from the ground during running.
FIGS. 12 (a) to 12(e) are lateral side views showing deformation of the lateral side of the rear foot part of the shoe sole of the first embodiment during landing.
FIGS. 13(a) to 13(d) are medial side views showing deformation of the medial side of the rear foot part of the shoe sole of the first embodiment during landing.
As described above, while the lower portions 31 of the tubular parts 130, 230, 330 and 430 undergo large bending deformation on the lateral and medial sides of the foot, the upper portions 32 of the tubular parts 130, 230, 330 and 430 perform relatively small bending deformation, during the period from the “heel-contact” to the “heel-rise”, as shown FIGS. 12(a) to 13(d).
During a series of motions from the time of the “heel-contact” to the time of the “heel-rise”, the lower portions 31 of the tubular parts 130, 230, 330 and 430 perform bending deformation and, as shown in FIGS. 12(c) and 13(c), end portions 233, 433 in the front side of the tubular parts 230, 430 in the fore of the rear foot part displace a little in the longitudinal direction with respect to the midsole M. The displacement of the end portions 233, 433 allows large bending deformation of the lower portions 31. It is speculated that the upper portions 32 is preferably curved to some extent so as to allow displacement of the end portions 233, 433.
On the lateral side of the rear foot part, the shoe sole sequentially makes contact with the ground forward from its rear end part and accordingly, the position on which a load is imposed is gradually moved forward. Therefore, by disposing the two tubular parts 130, 230 on the lateral side of the rear foot part of the shoe sole along the longitudinal direction, it is possible to effectively absorb shock over the whole area on the lateral side of the rear foot part.
On the other hand, on the medial side of the rear foot part, while the forward tubular part 430 undergoes large bending deformation, the rearward tubular part 330 undergoes small bending deformation. This is believed to be due to that, on the medial side of the rear foot part, the portion near the arch is subjected to a large load, while the portion near the heel is subjected to a small load. Therefore, the tubular part 330 in the rear of the medial side of the rear foot part may be replaced with the midsole M.
As understood from the fact that bending deformation of the tubular parts 330, 430 on the medial side of the rear foot part is larger than that of the tubular parts 130, 230 on the lateral side of the rear foot part, the foot can may incline toward the medial side during landing. To prevent this inclining for improving stability, in the deformation test, a vertical compression stiffness per unit area of each deformation element 3 on the lateral side of the rear foot part is set smaller than that of each deformation element 3 on the medial side of the rear foot part. As described above, this setting is achieved by making the Young's modulus of the shock absorbing member 35 in the tubular parts 330, 430 on the medial side larger than the Young's modulus of the shock absorbing member 35 in the tubular parts 130, 230 on the lateral side, or making stiffness of the tubular parts 330, 430 larger than stiffness of the tubular parts 130, 230 on the lateral side.
As described above, on the medial side of the rear foot part, the load imposed on the rearward tubular part 330 is far smaller than the large load imposed on the forward tubular part 430. Therefore, the compression stiffness of the forward deformation element (near the arch) of the two deformation elements on the medial side of the rear foot part may be set to be larger than that of the deformation element on the lateral side of the rear foot part and that of the deformation element in the rear of the medial side of the rear foot part.
The rear end portions 33 of the rearward tubular parts 130, 330 are disposed in the vicinity of the rear end of the outer sole 2. That is, the rear end portions 33. of the tubular parts 130, 330 are disposed at the rearmost position when the shoe sole makes contact with the ground. The lower portions 31 of the rearward tubular parts 130, 330 are formed in a substantially smooth arc shape in the longitudinal sectional view of the shoe sole (
With the tubular parts 130, 330 thus formed, in the period during which the state of the heel-contact where the foot lands on the ground as shown in
By receiving the load in this manner, the lower portions 31 of the tubular parts 130, 330 undergo bending deformation sequentially from the rear toward the front thereof. That is, by receiving the load in this manner, the region of the lower portions 31 of the tubular parts 130, 330 that undergoes bending deformation sequentially moves from the vicinity of the rear end portions 33 of the lower portions 31 toward the fore part thereof until it gets to the center of the lower portions 31 in the longitudinal direction, and furthermore, the region forward of the center also undergoes bending deformation.
Thus, since continuity of deformation is maintained and impact load of landing is absorbed continuously all over the period during which the state transfers, shock absorption function is enhanced. Moreover, since the deformed tubular parts 130, 330 return to the original shape during the transfer period or thereafter, the stored energy can be returned.
As shown in
In this manner, the deformation elements 3 in
Furthermore, since a plurality of deformation elements 3 each are provided in the fore and rear of the rear foot part, the foot of the wearer can be stably supported at the time of the foot-flat or in a standing position.
The front end portion 33 of the rearward deformation element 3 and the rear end portion 33 of the forward deformation element 3 are arranged so as to be close to each other in the longitudinal direction of the foot. This arrangement allows the longitudinal diameter Lr of each of the plurality of deformation elements 3 to be set large and thus, shock absorption function and energy storage function of the deformation elements 3 are improved.
In consideration of this, it is preferred that the deformation elements 3 are arranged separately from each other in the longitudinal direction of the foot.
In this embodiment, as shown in
In this embodiment, the connecting member for retaining the tubular part 30 is not provided, and the upper portion 32 of the tubular part 30 (lower half of the tubular part 30 in
The outer sole 2 is adhesive bonded onto the lower portion 31 of the tubular part 30 (upper half of the tubular part 30 in
FIGS. 17 to 19 show the third embodiment.
In this embodiment, as shown in
For example, a structure as disclosed in WO2005/037002 (PCT/JP2004/015042), the content of which is hereby incorporated herein by reference, may be employed for this shank 4a.
In this embodiment, the Young's modulus of the connecting member 4 is set larger than that of the midsole M and smaller than that of the tubular part 30, while, in the first embodiment, the Young's modulus of the connecting member 4 is about the same as that of the tubular part 30. Since such setting of this embodiment enables the connecting member 4 to retain the tubular parts 30 more softly, the upper portion 32 (
As shown in
As shown in FIGS. 19(a) and 19(b), in this embodiment, the cushioning member consists of a first cushioning member 35a formed of gel and a second cushioning member 35b formed of resin foam of EVA etc. A hole H is formed approximately in the center of the first cushioning member (longitudinal center of the tubular part 30), which hole has an axis substantially parallel to the minor axis of the tubular part 30. The second cushioning member H is fit into this hole H, thereby filling the hole H substantially completely. This hole H may be formed to pass through the first cushioning member 35a vertically as shown in
The second cushioning member 35b is made of a material that is softer and lighter than the first cushioning member 35a. This serves for weight saving and the increase in range of motion of gel, and therefore the repulsion force of the tubular part 30 can be enlarged and the endurance of the gel can be improved. Furthermore, since the hole H is located approximately in the longitudinal center of the tubular part 30, the cushioning members help to the deformation of the tubular part 30 so that the deformation in the vicinity of the end portions may be decreased and the deformation approximately in the center of the tubular part 30 may be increased.
Shock Absorption Function of Tubular Part:
Hereinafter, the result of the simulation of the case where static load was applied onto the tubular part disposed in the rear foot part will be shown in order to make clear the effect of the present invention.
First and second models were prepared: in the first model (
In these models, the length of the major axis Lr was set at 40.66 mm, the length of the minor axis Sr was set at 16 mm, the thickness of the tubular part 30 was set at 2 mm and the thickness of the outer sole was set at 5 mm. The radius of curvature of the lower portion 31 of the tubular part 30 in
In both models, Young's modulus of the tubular part 30 was set at 5.0 kgf/mm2 and Poisson's ratio of the tubular part 30 was set at 0.4; Young's modulus of the midsole M is set at 0.2 kgf/mm2 and Poisson's ratio of the midsole M is set at 0.01; Young's modulus of the outer sole 2 is set at 0.5 kgf/mm2 and Poisson's ratio of the outer sole 2 is set at 0.49.
First, in each model, the rear end of the shoe sole was pressed onto an inclined surface inclined at about 30 degrees to the horizontal as shown in FIGS. 6(b), 6(e), and thus a static load F1 was applied onto the shoe sole obliquely from rearward below as a supposed load at the time of landing. In the first model, the load F1 was set at about 0.35 kgf. In the second model, the load F1 was set at about 0.83 kgf, because the same load as the first model could make little deformation.
Consequently, in the first model, as shown in
Next, in each model, the rear portion of the shoe sole was pressed onto the horizontal surface as shown in FIGS. 6(c), 6(f), and thus a static load F1 was applied onto the shoe sole from below. In the first model, the load F2 was set at about 0.33 kgf. In the second model, the load F2 was set at about 1.31 kgf, because the same load as the first model could make little deformation.
Consequently, in the first model, as shown in
From these results, in the first model, it is speculated that the tubular part 30 can absorb much of the impact energy because the bulging lower portion 31 to be convex downwards undergoes bending deformation in spite of the direction of the loads F1, F2. On the other hand, in the second model, it is speculated that most of the impact energy is transferred to a portion of the midsole M above the end portion 33 because the flat (uncurved) lower portion 31 undergo only a small bending deformation in spite of the direction of the loads F1, F2.
From the above result of the simulation, it is speculated that, if the lower portion 31 is curved to be convex downwards and protruding from the midsole, the tubular part 30 can perform the shock absorption function sufficiently against the impact of landing. That is, it is speculated that, if the lower portion 31 of the tubular part 30 is curved to be convex downwards and protruding from the midsole, the tubular part 30 can store the impact energy of landing as deformation energy and therefore perform the repulsion function, sufficiently due to its leaf spring structure. However, if the whole of the lower portion 31 of the tubular part 30 is formed flat (uncurved) or if the lower portion 31 is not protruding downwards from the midsole, the tubular part 30 is difficult to undergo bending deformation, and therefore the tubular part 30 cannot absorb the shock of landing and cannot perform the repulsion function sufficiently. Accordingly, the first model (FIGS. 6(a) to 6(c)) falls within the scope of the present invention, while the second model (FIGS. 6(e) to 6(f)) is outside the scope of the present invention.
Various modified modification may be applied to the shapes of the tubular part 30, the outer sole 2 and the midsole 1.
For example, as shown in
The tubular part 30 need not necessarily be formed to be completely ring-shaped, and it may be formed by a modified tubular part 30 having a discontinuity in the longitudinal section and a end member 38 of rubber etc. which is disposed at this discontinuity, as shown in
As shown in
As shown in
Alternatively, the tubular part 30 may be formed in shapes shown in perspective views of FIGS. 8(a) to 8(e) or in shapes shown in sectional views of FIGS. 9(a) to 9(h).
That is, as shown in FIGS. 8(a), 8(b), the outer surface of the tubular part may be curved along the medial-lateral direction X at the front and rear end portions 33, 33. As shown in
As shown in FIGS. 9(a) to 9(c), the upper portion 32 and/or the lower portion 31 the tubular part 30 may be formed so that its medial or lateral end portion curls upwards. As shown in
While preferred embodiments of the present invention have been described above with reference to the drawings, obvious variations and modifications will readily occur to those skilled in the art upon reading the present specification.
For example, although, in the first and third embodiment, the cushioning member 35 is arranged approximately in the longitudinal center of the internal space of the tubular part 30, the shape and the arrangement of the cushioning member 35 is not limited to those of these embodiments. Alternatively, the cushioning member may be shaped and arranged as shown in FIGS. 10(a) to 10(h).
The number and the arrangement of the deformation elements is not limited to those of the embodiments. For example, two or three deformation elements or more than five elements may be arranged in the rear foot part. The deformation elements may be provided only in the lateral side in the rear foot part.
Thus, such variations and modifications shall fall within the scope of the present invention as defined by the appended claims.
The present invention is applicable to shoe soles of various shoes such as athletic shoes.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-286577 | Sep 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/12326 | 7/4/2005 | WO | 1/4/2007 |
