Patent Publication Number: US-8973287-B2

Title: Shoe midsole and footwear

Description:
FIELD OF THE INVENTION 
     The present invention relates to a shoe midsole and footwear which can absorb a shock during walking while producing a walking feeling of stability and comfort, reduce a load on a foot, a knee, etc. in a standing position, and stimulate a sole of a foot to be massaged. 
     BACKGROUND OF THE INVENTION 
     It is conventionally believed that when a heel touches down on the ground, the shock applied to the heel is approximately 1.25 times higher than the human body weight during walking, and approximately three times higher than the human body weight during jogging. This shock is sequentially sent to the heel, an ankle, a knee, and hips. 
     Conventionally, a sole made of an elastic material is known as a shoe midsole for absorbing the shock applied when the heel touches down the ground. This elastic material absorbs the shock in the contacting area to the ground when the heel touches down on the ground. 
     Accordingly, the present applicant has proposed a technical means to spread and absorb the shock when the sole of a foot touches down on the ground during walking, and to stimulate the sole of a foot to be massaged (for example, see Patent Document 1). 
     Patent Document 1 disclosed that a fluid infused between a sole plate and a cover could spread and absorb the shock when the sole of a foot touched down on the ground, and could reduce a load on a knee, hips, etc. Patent Document 1 also disclosed the effect that the shock to the sole of a foot could be spread and absorbed with the fluid smoothly moved by uniformly tilting a plurality of blades toward the heel side, and the effect that the blades could massage the sole of a foot. 
     By the way, when we human being walk, we take a series of actions as follows: to contact with the ground as the first action, gradually contact a sole with the ground from the heel to the roots of toes as the next action, and to kick the ground with the toes as the last action. This series of actions is continuously repeated as one cycle of the actions. 
     Until now, it has been considered that the peak impact force is generated at the moment when the heel touches down on the ground within the one cycle of walking. However, it has been revealed that the impact force generated at the moment of kicking the ground of the roots of the toes is higher than the impact force generated at the moment of touchdown of heel on the ground as a simulation described later in  FIG. 6 . 
     However, according to the Patent Document 1 described above, the plurality of blades were uniformly tilted toward the heel side and it meant that the plurality of blades were same as the moving direction of the fluid at the moment of kicking the ground of the roots of the toes. Therefore, the fluid in the toe side is quickly moved to the heel side, and there is some risk, that the shock applied to the heel side is increased. 
     [Patent Document 1] U.S. Pat. No. 1,959,712 (Examined Patent Publication No. H6-91849) 
     DISCLOSURE OF THE INVENTION 
     The present invention provides a shoe midsole and footwear which can relieve a shock applied to a sole of a foot during walking, reduce a load on a knee, etc. during walking, and massage the sole of the foot. 
     SUMMARY OF THE INVENTION 
     A shoe midsole according to the present invention has a sole plate, a plurality of blades standing on the sole plate, a cover bonded to an outer circumference of the sole plate, and a fluid sealed between the sole plate and the cover. In the shoe midsole, a first concave part in a shape equivalent to a sole of a foot is formed on a surface of the sole plate, on which the plurality of blades stand, therefore, the plurality of blades are accommodated within the first concave part and are arranged at a predetermined interval in a direction nearly orthogonal to the longitudinal direction of the sole plate, and at least some of the blades are tilted toward a toe. 
     A footwear according to the present invention has a footwear midsole which is placed on a footwear base and comprises a sole plate, a plurality of blades integrally standing on the sole plate, a cover bonded to the outer circumference of the sole plate, and a fluid sealed between the sole plate and the cover. In this footwear, a first concave part in a shape equivalent to a sole of a foot is formed on a surface of the sole plate, on which the plurality of blades stand, and the plurality of blades that are accommodated within the first concave part are aligned at predetermined intervals in a direction nearly orthogonal to the longitudinal direction of the sole plate, and at least some of the blades are tilted toward a toe. 
     EFFECT OF THE INVENTION 
     According to the present invention, the shoe midsole and footwear can control the fluid movement during walking and can massage the sole of a foot with the plurality of blades. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external perspective view partially broken away of a shoe midsole according to a first embodiment, 
         FIG. 2  is a top view of a sole plate, 
         FIG. 3  is a fragmentary cross-sectional view of the sole plate and a cover when being cut along a longitudinal direction of the sole plate, 
         FIG. 4  is a fragmentary cross-sectional view of the sole plate and the cover when being cut along an orthogonal direction to the longitudinal direction of the sole plate, 
         FIG. 5  is a top view of the cover when viewed in the V direction shown in  FIG. 3 , 
         FIG. 6  is a graph illustrating pressure applied to a sole of a foot during walking simulation in a case where all or some of the blades are tilted toward a toe, 
         FIG. 7  is a fragmentary cross-sectional view of the sole plate and a cover when being cut along a longitudinal direction of the sole plate according to a second embodiment, 
         FIG. 8  is a fragmentary cross-sectional view of the sole plate and a cover when being cut along a longitudinal direction of the sole plate according to a third embodiment, 
         FIG. 9A  is an overall perspective view of a men&#39;s shoe having a heel in a situation where a shoe midsole and an insole are inserted into an opening according to a fourth embodiment, 
         FIG. 9B  is an exploded perspective view of a footwear base, the shoe midsole and the insole of a men&#39;s shoe, 
         FIG. 10A  is an overall perspective view of a women&#39;s shoe having a heel in a situation where a shoe midsole and an insole are inserted into an opening, 
         FIG. 10B  is an exploded perspective view of a shoe footwear base, the shoe midsole and the insole of the women&#39;s shoe, 
         FIG. 11A  is an overall perspective view of a men&#39;s shoe without a heel in a case where a shoe midsole is integrally fixed to a footwear base in a fifth embodiment, 
         FIG. 11B  is an exploded perspective view of the footwear base, the shoe midsole and the insole, 
         FIG. 11C  is a back view of the shoe midsole covered by the insole, and fixed to the insole with an adhesive, 
         FIG. 12A  is an overall perspective view of a women&#39;s shoe without a heel in a case where a shoe midsole is integrally fixed to a footwear base, 
         FIG. 12B  is an exploded perspective view of a footwear base, the shoe midsole and the insole; and 
         FIG. 12C  is a back view of the shoe midsole covered by the insole, and fixed to the insole with an adhesive; 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The First Embodiment 
     The first embodiment according to the present invention is described below by using the drawings. 
       FIG. 1  is an external perspective view partially broken away of a shoe midsole  10 . The shoe midsole  10  has a sole plate  11 , a cover  13  bonded to the sole plate  11  along the outer circumference with welding, etc., a fluid  14  sealed between the sole plate  11  and the cover  13 , and a sheet  18  bonded on the back surface of the sole plate  11 . 
     The sole plate  11  is made of a thermoplastic resin such as polyvinyl chloride resin, and is molded with injection molding, etc. A plurality of blades  12  are integrally formed on the sole plate  11 . The details of the plurality of the blades  12  will be described later. The sole plate  11  is bonded to the cover  13  via their respective welding surfaces  19 ,  19 ′. The sole plate  11  and the cover  13  are made of same kind of thermoplastic resins. 
     However, the sole plate  11  and the cover  13  can be made of different type of materials so far as they can be bonded together. The fluid  14  preferably has low water permeability, low-level evaporation, high fluidity and anti-deterioration. This fluid  14  is infused through an inlet  25  in the heel side. 
     As the fluid  14 , for example, a water mixed with antifreeze liquid is preferably used so that the fluid  14  can not freeze in cold regions. In the first embodiment, propylene glycol is used as the fluid  14 . 
     The sheet  18  is bonded to the sole plate  11  to reduce discomfort during walking by preventing the fluid  14  from leaking to the outside even if the fluid  14  breaks through the sole plate  11 . Also, the sheet  18  is made of, for example, a thermoplastic resin. If there is no possibility that the fluid  14  will break through the sole plate  11 , the sheet  18  can be omitted. 
       FIG. 2  is a top view of the sole plate  11 . 
     As illustrated in  FIG. 2 , a first concave part  15  having an equivalent shape (similar shape) to a sole of a foot is formed on the upper surface of the sole plate  11 . Moreover, a circumference  16  is formed so as to surround the first concave part  15  via an inner wall  15   a  and the welding surface  19 . The welding surface  19  is formed on a thick part  23  (see  FIG. 4 ). Some area of the first concave part  15  on the toe side may extend to the base of the toes. Desirably, however, the toe side of the first concave part  15  does not extend to the base of the toes, so as to facilitate walking. 
     Additionally, a partition  17  standing on the sole plate  11  is successively formed inside of the first concave part  15 . The detail of the partition  17  will be described later. The partition  17  is hatched in  FIG. 2  in order to be easily distinguished from the other parts. 
     Furthermore, plurality of blades  12 - 1  to  12 - 16  are arranged so as to integrally stand on the first concave part  15 . The plurality of blades  12  are aligned at a predetermined interval along a direction nearly orthogonal to the longitudinal direction of the sole plate  11 . In the first embodiment, all of the blades  12 - 1  to  12 - 16  are respectively aligned at a nearly equal interval from the heel to the toe. 
     The blades  12  have an important function to adequately stimulate the pressure points on the sole of a foot owing to its nature of the elastic material. It is known that many pressure points related to physical health are concentrated on the sole of a foot. 
     A collaborative action of the elastic force of the blades  12  and the fluid  14  absorbs a shock applied to the sole of a foot, and also stimulates and massages the pressure points adequately during walking. 
       FIG. 3  is a cross-sectional view of the sole plate  11  and the cover  13  bonded thereto when being cut along the longitudinal length. 
     As shown in  FIG. 3 , at least some of the plurality of blades  12 - 1  to  12 - 16  are arranged so as to be uniformly tilted toward the toe side. This embodiment represents a case where all of the blades  12 - 1  to  12 - 16  are arranged to be tilted toward the toe side. 
     Namely, all of the blades  12 - 1  to  12 - 16  are arranged to be uniformly tilted toward the toe side at an angle θ (approximately 45 degrees) with respect to a direction y-y nearly orthogonal to the longitudinal direction of the sole plate  11 . In this embodiment, approximately 45 degrees is selected as the angle θ. However, the angle θ is not limited to 45 degrees. 
     As shown in  FIG. 3 , a level difference h 1  is provided between the first concave part  15  and the circumference  16 . Moreover, the thick part  23  is formed along the inside of the circumference  16  of the sole plate  11  as the bonded (welded) area with the cover  13 . The thick part  23  has the welding surface  19 . Moreover, a tilted inner wall (tilted surface)  15   a  and a tilted outer wall (tilted surface)  15   b  are formed along the boundary between the first concave part  15  and the circumference  16 . The reason why the level difference h 1  is provided is to prevent the sole plate  11  from distortion. 
     Additionally, a second concave part  21  is formed on the cover  13  so as to face the first concave part  15 . A level difference h 2  is provided between the second concave part  21  and a circumference  22  formed to surround the second concave part  21 . Moreover, a tilted inner wall (tilted surface)  21   a  and a tilted outer wall (tilted surface)  21   b  are formed along the boundary between the second concave part  21  and the circumference  22 . A welding surface  19 ′ (surface to be welded) is formed along inside of the circumference  22 , facing the welding surface  19  of the sole plate  11 . 
     In this embodiment, the welding surface  19  of the circumference  16  of the first concave part  15  and the welding surface  19 ′ of the circumference  22  of the second concave part  21  are welded. The reason why the level difference h 2  is provided is to prevent the cover  13  from distortion. 
     In this way, the welding surface  19  of the sole plate  11  and the welding surface  19 ′ of the cover  13  are welded so as to combine the cover  13  with the sole plate  11 . When the sole plate  11  and the cover  13  are welded, the welding area melts and then reduces its thickness. Therefore, the thick part  23  having large thickness is formed on the sole plate  11 . 
     The width (horizontal width) of the thick part  23  is formed to be slightly wider than the width of the welding surface  19 . This is because water leakage possibly occurs through the welding area of the sole plate  11  if the width of the thick part  23  is narrower than that of the welding surface  19 . 
     As described above, the sole plate  11  and the cover  13  are welded to be sealed in the shape of a bag, in which said fluid  14  is sealed. 
     The inlet part  25  (see  FIG. 1 ) is left without being welded. And the outside of the welding surface  19  is left without being welded. 
     In this embodiment, it is described that the tilted surfaces  15   a ,  15   b  are formed along the boundary between the first concave part  15  and its circumference  16 , and the tilted surfaces  21   a  and  21   b  are formed along the boundary between the second concave part  21  and its circumference  22 . However, these tilted surfaces can be changed to arc-shaped surfaces or curved surfaces. 
     In the meantime, the sole of a foot of a human being is so sensitive as to feel uncomfortable when a small stone rests on the bottom of a shoe for example. Therefore, it is especially desirable that the welding surface  19 ′ of the cover  13  is preferably maintained in flat surface condition without unevenness after the thick part  23  is welded. 
     In this embodiment, as the welding surfaces  19 ,  19 ′ are welded together with a nearly equal width, the bonding strength can be uniform, then the water leakage can be prevented and the flat surface condition can be maintained without causing twist etc. on the shoe midsole  10  as a whole. And in this embodiment, the thick part  23  is formed to have a uniform width. This is because the welding surfaces  19 ,  19 ′ are welded with an almost uniform width. Furthermore, non-welding surfaces surrounding the welding surfaces  19 ,  19 ′ are spot-welded together at several points, and sand and dust can be prevented from entering into the gap between the sole plate  11  and the cover  13 . 
       FIG. 4  is a cross-sectional view of the sole plate  11  and the cover  13  when being cut along a direction nearly orthogonal to the longitudinal direction of the sole plate  11 . 
     As shown in  FIG. 4 , both ends of the upper surface of the blade  12  are formed in a shape of moderately curved arc each other, and edges of both sides of the blade  12  do not reach the partitions  17  formed along the inside of the circumference of the first concave part  15 . Moreover, grooves  20  are formed on the upper surface of the blade  12  between its both ends. The grooves  20  are formed so that the fluid  14  can move in the longitudinal direction of the sole plate  11 . In this embodiment, the two grooves  20  are formed at a predetermined interval on every blade  12 . 
     The number of grooves  20  is not particularly limited. Moreover, the cross-section of the groove  20  is formed in the shape of a rectangle in this embodiment. However, the shape of the groove  20  may not particularly be limited. The shape of cross-section of the groove  20  can be semi-circular or U-shaped. Additionally, the grooves  20  are formed on the upper surface (the surface near the cover  13 ) of the blade  12  in this embodiment. However, the grooves  20  can be formed on the bottom side (the side facing the first concave part  15 ). 
     As shown clearly in  FIG. 4 , the inner wall  15   a  of the sole plate  11  is formed to be continuously and gradually tilted up toward the circumference  16 . By forming the inner wall  15   a  to be tilted in this way, the fluid  14  can be smoothly moved, and the inner wall  15  can be prevented from getting pressure. The cover  13  has the similar characteristics. 
     Additionally, the partition  17  described above is formed to integrally stand on the sole plate  11  along the inside of the circumference of the first concave part  15  between both ends of the blade  12  and the inner wall  15   a  of the first concave part  15 . 
     The partitions  17  have a function to prevent the fluid  14  from leaking by preventing the fluid  14  from directly contacting the respective welding surfaces  19 ,  19 ′ (see  FIG. 1 ) of the sole plate  11  and the cover  13 . In this embodiment, it is one of the important subjects to prevent the fluid  14  from leaking. 
     For example, the fluid  14  within the concave parts  15 ,  21  moves with high pressure when the toes kick the ground during walking. The partitions  17  has the function to prevent the fluid  14  having high pressure from breaking through and leaking through the respective welding surfaces  19 ,  19 ′ of the sole plate  11  and the cover  13 . 
     It is because the impact force applied to the shoe midsole at the movement of a body weight during walking is beyond understandable level based on the common sense. In this embodiment, the horizontal position of the top surface of the partitions  17  is nearly equal to the horizontal position of the upper surface of the circumference  16  of the sole plate  11 . 
     Considering the walking actions, a heel portion of the foot touches down on the ground at first, and the area contacting the ground is expanding toward an arch of a foot, and after bearing the body weight on a swelled portion (ball portion) of the base of the toes, the toes horizontally spread to suppress a stagger in the horizontal or vertical direction. Next, the base of the toes starts to bend the ball portion while the center of gravity moves forward, then the heel portion goes up, and all the toes kick the ground. At this time, the fluid  14  sealed inside moves to evenly absorb and reduce the shock of touchdown on the shoe midsole  10  of this embodiment. 
     In this regard, when a pressure is partially applied to a liquid sealed within a container, for example, the pressure is spread to all the inner surfaces of the container (Pascal&#39;s Law). Therefore, based on the above, when the shoe midsole  10  of this embodiment is used, a water pressure equal to or higher than a body weight of a person is evenly applied to all over the surface contacting the cover  13 . Moreover, the elastic force of the plurality of blades  12  is relieved by the movement of the fluid  14 . 
       FIG. 5  is a schematic illustrating the cover  13  when viewed in a V direction shown in  FIG. 3 . 
     As described above, the second concave part  21  of the cover  13  is formed correspondingly to the first concave part  15  of the sole plate  11 . A circumference  22  is formed along the outside of a circumference of the second concave part  21  via the inner wall  21   a  and the welding surface (surface to be welded)  19 ′. 
     The respective planar shapes of the second concave part  21  and the circumference  22  are nearly equal to those of the first concave part  15  and the circumference  16  of the sole plate  11 . The thickness of the circumference  22  is nearly equal to that of the circumference  16  of the sole plate  11  except the thick part  23 . 
     Additionally, an uneven pattern such as a mat pattern or a pear-skin pattern is formed on the upper surface of the cover  13  when needed, although this is not illustrated in  FIG. 5 . The uneven pattern can prevent sweat from gathering as droplets on the upper surface of the cover  13 , and can promote diffusion and evaporation of the droplets. 
     After the sole plate  11  and the cover  13  are welded together, the fluid  14  is infused through the inlet  25  (see  FIG. 1 ) into the space enclosed with the first concave part  15  and the second concave part  21 . Thereafter, the inlet  25  is welded to seal the fluid  14 . 
       FIG. 6  is a graph illustrating changes in a pressure applied to a sole of a foot when a walking simulation is performed in the case of tilting all or some of the blades  12  toward the heel or the toe. 
     In this figure, the horizontal and the vertical axes represent time and a (non-dimensional) pressure value applied to the sole of a foot at that time, respectively. 
     In this embodiment (the first embodiment), all of the blades  12 - 1  to  12 - 16  were uniformly tilted toward the toe (curved line A), and a tilting angle was changed (curved line B). Changes in the pressure applied to the sole of a foot at this time were represented with the curved line A (solid thickened line) and the curved line B (dotted line). 
     A curved line E (dotted line) represents, as a comparison example, the case where the blades  12  were uniformly tilted toward the heel side. A curved line C (solid thin line) and a curved line D (dashed-dotted line) will be later described in the second and the third embodiments. 
     A point P 1  in this figure indicates a pressure applied to the sole of a foot just before the heel of the foot touched down on the ground during walking. Then the touchdown of the heel terminated at a point P 2  (the body weight was applied). Next, a point P 3  indicates a pressure applied to the sole of a foot while the body weight was transferred from the heel to the toe side. A point P 4  indicates a pressure applied when the toes kicked the ground (the body weight was applied). After the toes kicked the ground, the body weight was transferred and then the heel of the foot went to the point P 1  in the next step. The above was one cycle of walking of a person. 
     Here, the curved line A represents the pressure applied to the sole of a foot in the case where the blades  12  formed on the sole plate  11  were uniformly tilted toward the toe side at an angle α (such as 10 degrees). 
     The curved line B represents the pressure applied to the sole of a foot in the case where the blades  12  were uniformly tilted toward the toe side at an angle θ (such as 45 degrees) (θ&gt;α). 
     The curved line E represents changes in the pressure applied to the sole of a foot in the case where the blades  12  were uniformly tilted toward the heel side at the angle α (such as 10 degrees). 
     On the curved line A, the pressure (point P 2 ) applied at the moment of touchdown of the heel on the ground was approximately 38000 (non-dimensional), and the pressure (point P 4 ) applied at the moment of kicking the ground of the toes was 64000. In contrast, on the curved line B, the pressure (point P 2 ) applied at the moment of touchdown of the heel on the ground was approximately 35000, and the pressure (point P 4 ) applied at the moment of kicking the ground of the toes was 53000. 
     According to the above result, the case of the curved line A where the blades  12  have the smaller tilting angle (angle α) is higher than the case of the curved line B where the blades  12  have the larger tilting angle (angle θ) both in the pressure (point P 2 ) applied at the moment of touchdown of the heel on the ground and in the pressure (point P 4 ) applied at the moment of kicking the ground of the toes. 
     The reason of the above is considered that the pressure directly applied to the sole of a foot became higher in the case having the small tilting angle (angle α) of the blades  12  as shown in the curved line A 
     In the meantime, on the curved line E, the pressure (point P 2 ) applied at the moment of touchdown of the heel on the ground was approximately 39000 (non-dimensional), and the pressure (point P 4 ) applied at the moment of kicking the ground of the toes was 64000. 
     Namely, though the curved line E is almost the same as the curved line A as a whole, the pressure (point P 2 ) applied at the moment of touchdown of the heel on the ground on the curved line E was slightly higher than that on the curved line A. Moreover, the pressure (point P 4 ) applied at the moment of kicking the ground of the toes on the curved line E was nearly equal to that on the curved line A. 
     The reason why the pressure at the point P 2  on the curved line E was slightly higher than that on the curved line A is considered that a pressure directly applied to the sole of a foot in the case where the blades  12  were tilted toward the heel side (curved line E) was higher than that in the case where the blades  12  were tilted toward the toe side (curved line A). 
     Additionally, the pressures at the point P 4  on the curved lines A and E were nearly equal. 
     Furthermore, a difference between the pressure applied at the moment of kicking the ground of the toes (point P 4 ) and the pressure applied at the moment of touchdown of the heel on the ground (point P 2 ) was smaller on the curved line B than those on the curved lines A and E. 
     It is said that comfortable walking with less strain can be achieved in the case that the difference between the pressure applied at the moment of kicking the ground of the toes and the pressure applied at the moment of touchdown of the heel on the ground is smaller. From this viewpoint, it is proved that when the blades  12  are tilted toward the toe side, it is desirable to select slightly larger tilting angle (angle θ) rather than to select smaller tilting angle (angle α). 
     The reason of the above is considered that if the blades  12  are arranged to be uniformly tilted toward the toe, a resistance is given to the sealed fluid  14  in the opposite direction of the movement of the fluid  14  due to the reverse tilting angle of the blades  12 , especially when the toes kick the ground, and the resistance suppresses rapid movement of the fluid  14  from the toe side to the heel side. 
     Namely, as illustrated in  FIG. 6 , although the toes kick the ground after the heel touches down on the ground during walking, the touchdown force of the heel is smaller than the kicking force of the toes. Therefore, the moving speed of the fluid  14  from the heel side to the toe side is rather slower when the heel touches down on the ground. In contrast, as the force generated at the moment of kicking the ground of the toes is large, the moving speed of the fluid  14  from the toe side to the heel side is very fast when the toes kick the ground. 
     However, in this embodiment (curved lines A and B), as the blades  12  are uniformly tilted toward the toe side, a resistance in the opposite direction of the movement of the fluid  14  is given to the fluid  14  when the fluid  14  moves from the toe side to the heel side at the time when the toes kick the ground. From the above result, the moving speed of the fluid  14  slows down. In this way, the pressure applied to the sole of a foot (especially, the pressure applied when the toes kick the ground) can be reduced. 
     Additionally, in this embodiment, the shape of the first concave part  15  of the sole plate  11  (and the second concave part  21  of the cover  13 ) is formed to be similar to the sole of a foot (see  FIG. 2 ). Consequently, the volume of the sealed fluid  14  in the toe side is larger than that in the heel side. Therefore, the fluid  14  attempts to move from the toe side to the heel side at high speed when the toes kick the ground. However, as the blades  12  are uniformly tilted toward the toe side and a resistance against the movement of the fluid  14  is generated, the movement of the fluid  14  to the heel side is suppressed when the toes kick the ground. 
     By the way, the optimum value of the tilting angle of the blades  12  has not been obtained at the present time. This is because when the tilting angle of the blades  12  changes, not only the pressure value applied to the sole of a foot but also influences of other elements (change in the flow path of the fluid  14 , and ease of walking, etc.) are exerted, therefore, these factors should be considered together as a whole. 
     This embodiment refers to the case where the present invention is applied to the shoe midsole. However, the present invention is not limited to this implementation, and may be directly applied, for example, to the bottom of a shoe. 
     In this embodiment, the pressure applied at the moment of kicking the ground of the toes is reduced by arranging all the blades  12 - 1  to  12 - 16  to be uniformly tilted toward the toe, and then a shock transferred to the knee and the hips, etc. from the heel can be absorbed and a comfortable walking feeling can be produced. Though elastic force of the blades  12  actually massages the sole of a foot, the fluid  14  relieves the elastic force of the blades  12  and stimulates the sole of a foot, whereby comfortable walking can be continued for a long time. 
     The Second Embodiment 
       FIG. 7  is a cross-sectional view of the sole plate  11  and the cover  13  according to the second embodiment, cutting along the longitudinal direction. Members identical or equivalent to those in the first embodiment are denoted with the same reference numbers, and their descriptions are omitted. 
     In this embodiment, some of the blades  12  are arranged to be tilted toward the toe from the center of the longitudinal length of the sole plate  11  to the heel, and other blades are arranged to be tilted toward the heel from the center to the toe. 
     Namely, as illustrated in  FIG. 7 , the eight blades  12 - 1  to  12 - 8  are arranged to be uniformly tilted toward the toe at a predetermined angle θ (such as 45 degrees) from the center of the longitudinal length of the sole plate  11  to the heel, and the rest of the blades  12 - 9  to  12 - 16  are arranged to be uniformly tilted toward the heel at the predetermined angle θ (such as 45 degrees) from the center to the toe. Each blade  12  has a base  104  at the sole plate  11  and extends to a distal end  102 . As shown in  FIG. 7 , distal ends  102  of the blades  12 - 1  to  12 - 8  are closer to the toe than the bases  104  of such blades; and distal ends  102  of the blades  12 - 9  to  12 - 16  are closer to the heel than the bases  104  of such blades. 
     The curved line C (solid thin line) illustrated in  FIG. 6  represents changes in the pressure applied to the sole of a foot in this embodiment. 
     According to the curved line C, the pressure (point P 2 ) applied at the moment of touchdown of the heel on the ground was approximately 36000, and the pressure (point P 4 ) applied at the moment of kicking the ground of the toes was 53000. Namely, the difference between the maximum pressure at the time of kicking and that at the time of touchdown was 17000, therefore, the pressure difference was the smallest as to the curved lines illustrated in  FIG. 6 . 
     Therefore, comfortable walking with less strain can be also achieved in this embodiment. 
     The reason of the above is considered that a reverse resistance is applied to the fluid  14  by the blades  12  arranged from the center to the toe side to be uniformly tilted toward the heel side, though the fluid  14  sealed in the heel side moves from the heel to the center when the heel touches down on the ground. Accordingly, the fluid  14  in the heel side moves back and forth between the center and the heel, and the moving speed is slowed down, thereby the shock applied to the heel is reduced. 
     Next, a reverse resistance is applied by the blades  12  arranged from the center to the heel side to be uniformly tilted toward the toe side, even though the fluid  14  sealed in the toe side moves from the toe to the center when the toes kick the ground. Accordingly, the fluid  14  in the toe side moves back and forth between the center and the toe. Moreover, the moving speed is slowed down by the reverse resistance, thereby the shock applied to the toe is reduced. 
     According to this embodiment, the blades  12  arranged from the center of the longitudinal length of the sole plate  11  to the heel are uniformly tilted toward the toe, and the blades  12  arranged from the center to the toe are uniformly tilted toward the heel. Therefore, a resistance in the opposite direction of the movement of the sealed fluid  14  is applied to the fluid  14 , thereby the rapid movement of the fluid  14  can be suppressed. 
     The Third Embodiment 
       FIG. 8  is a cross-sectional view of the sole plate  11  and the cover  13  according to the third embodiment, cutting along the longitudinal direction. Parts identical to or equivalent to those of the first embodiment are denoted with the same reference numbers, and their descriptions are omitted. 
     In this embodiment, the blades  12  arranged from the center of the longitudinal length of the sole plate  11  to the heel are tilted toward the heel, and the blades  12  arranged from the center to the toe are tilted toward the toe. 
     In the second embodiment, the blades  12  arranged from the center of the longitudinal length of the sole plate  11  to the heel are tilted toward the toe. However, in the third embodiment the blades  12  arranged from the center to the toe are tilted toward the toe, and that is the different point from the second embodiment. 
     As illustrated in  FIG. 8 , the eight blades  12 - 1  to  12 - 8  arranged from the center of the longitudinal length of the sole plate  11  to the heel are uniformly tilted toward the heel at a predetermined angle θ (such as 45 degrees), and the blades  12 - 9  to  12 - 16  arranged from the center to the toe are uniformly tilted toward the toe at the predetermined angle θ (such as 45 degrees). 
     The curved line D (dashed-dotted line) illustrated in  FIG. 6  represents changes in the pressure applied to the sole of a foot in this embodiment. 
     According to the curved line D, the pressure (point P 2 ) applied at the time of touchdown of the heel on the ground was approximately 33000, and the pressure (point P 4 ) applied at the time of kicking the ground of the toes was 55000. Namely, the difference between the maximum pressure at the time of kick and that at the time of touch down was 22000. 
     According to the curved line D, the difference between the maximum pressure at the time of kick and that at the time of touchdown was smaller than that of the curved line A. Therefore, comfortable walking with less strain can be expected to be achieved in a similar manner as in the first and the second embodiments. 
     The above is considered that when the toes kick the ground, a reverse resistance is applied to the fluid  14  sealed in the toe side by the blades  12  uniformly tilted toward the toe side between the center and the toe side, and also the moving speed of fluid is slowed down, whereby the large shock applied to the toe can be reduced. 
     And it is also considered that when the heel touches down on the ground, a reverse resistance is applied to the fluid  14  sealed in the heel side by the blades  12  uniformly tilted toward the heel side between the center and the heel side, and then the moving speed of fluid is slowed down, whereby the shock applied to the heel can be reduced. 
     Additionally, when the toe kicks the ground, a reverse resistance is applied to the fluid  14  sealed in the toe side by the blades  12  arranged from the center to the toe and uniformly tilted toward the toe, and then the moving speed of the fluid is slowed down, whereby the shock applied to the sole of a foot is reduced in a similar manner as in the above embodiments. 
     The Fourth Embodiment 
       FIGS. 9A ,  9 B,  10 A and  10 B are overall views and exploded perspective views of footwear (men&#39;s shoe  30  and women&#39;s shoe  40 ) according to the fourth embodiment. 
     This embodiment refers to the case where the shoe midsole  10  as a footwear midsole is arranged to be freely inserted and extracted on a footwear bases  31 ,  41  of the men&#39;s shoe  30  and the women&#39;s shoe  40 . As portions other than the footwear bases  31 ,  41 , insoles  34 ,  44 , and the shoe midsole  10  do not directly relate to the present invention, any descriptions of them are omitted. 
       FIG. 9A  is an overall perspective view of the men&#39;s shoe  30  with a heel in the situation where the shoe midsole  10  and the insole  34  are inserted into a foot opening  37 , and  FIG. 9B  is an exploded perspective view of the footwear base  31  of the men&#39;s shoe  30 , the shoe midsole  10 , and the insole  34 . 
     The footwear base  31  of the men&#39;s shoe has an outsole  32  and a middle sole (midsole)  33 . A heel  36  is made, for example, as an independent part by stacking a plurality of sheets of leather. The outsole  32  is the bottom portion of the shoe, and generally made of a high cushioning material. The middle sole  33  is also called a midsole, and mainly located to improve the stiffness, the anti-bending and the shock absorption of the shoe. The outsole  32  and the middle sole  33  are bonded with an adhesive, stitched with a thread, or united by being integrally molded. The insole  34  is made of, for example, one sheet of leather. 
     In this embodiment, the shoe midsole  10  and the insole  34  are detachably placed on the middle sole  33  in this order so as to be freely inserted into and extracted from the foot opening  37 . Namely, the shoe midsole  10  and the insole  34  are placed without being adhered, etc. so that a customer can freely insert and extract them. The insole  34  is made of one sheet of leather, and a woven label  35  that displays the brand name of a manufacturer, etc. is stitched on the upper surface of the insole  34 . 
     For actual use, the shoe can be used by removing the insole  34  according to customer&#39;s preference. In this case, the shoe is used in a condition where the shoe midsole  10  is exposed. 
       FIG. 10A  is an overall perspective view of the women&#39;s shoe  40  with a heel in the situation where the shoe midsole  10  and the insole  44  are inserted into a foot opening  47 , and  FIG. 10B  is an exploded perspective view of the footwear base  41  of the women&#39;s shoe  40 , the shoe midsole  10  and the insole  44 . 
     The footwear base  41  of the women&#39;s shoe  40  has an outsole  42  and a middle sole (midsole)  43 . The outsole  42 , the middle sole  43 , the insole  44 , a heel  46  and a woven label  45  are similar to those of the above described men&#39;s shoe  30 . Therefore, their descriptions are omitted. 
     According to this embodiment, the shoe midsole  10  and the insole  44  are detachably placed on the middle sole  43  in this order so as to be freely inserted into and extracted from the foot opening  47 . Namely, the shoe midsole  10  and the insole  44  are arranged without being adhered, etc. so that a customer can freely insert and extract them. 
     For actual use, the shoe can be used by removing the insole  44  according to customer&#39;s preference. In this case, the shoe is used in a condition where the shoe midsole  10  is exposed. 
     This embodiment refers to the case where the shoe midsole  10  is arranged on the footwear bases  31 ,  41  of the men&#39;s shoe  30  and the women&#39;s shoe  40  to be freely inserted and extracted. However, this embodiment is not limited to the above implementations. For example, the shoe midsole  10  can be arranged to be freely inserted into and extracted from other footwear such as a sport shoe, a sneaker, a strapped or non-strapped sandal, a business shoe, a ski shoe, a golf shoe, a hiking shoe, a walking shoe, a boot, a long boot, an indoor shoe, a Japanese sandal, a slipper, a sock, etc. If there is a portion covering the upper portion of the footwear base  31 ,  41 , or a strap, the shoe midsole  10  does not come off easily even if it is arranged to be freely inserted and extracted. 
     According to this embodiment, as the shoe midsole  10  is arranged on the footwear bases  31 ,  41  of the men&#39;s shoe, etc. to be freely inserted and extracted, the midsole  10  can be easily installed in the men&#39;s shoe, etc. For example, if the effects of shock absorption and massage for the sole of a foot are desired to be improved during walking, the shoe can be used by removing the insoles  34 ,  44 . Similarly, the shoe midsole  10  can reduce a burden on a foot, a knee, etc. in a standing position. 
     The Fifth Embodiment 
       FIGS. 11A to 11C  and  12 A to  12 C are respectively external views, exploded perspective views, and a back view of footwear (men&#39;s shoe  50  or women&#39;s shoe  60 ) according to the fifth embodiment. 
     This embodiment refers to the case where the shoe midsole  10  as a footwear midsole is integrally bonded to respective footwear bases  51 ,  61  of the men&#39;s shoe  50  and the women&#39;s shoe  60 . Portions other than the footwear bases  51 ,  61 , insoles  54 ,  64 , and the shoe midsole  10  do not directly relate to the present invention. Therefore, their descriptions are omitted. 
       FIG. 11A  is an overall perspective view of a situation where the shoe midsole  10  is integrally fixed to the footwear base  51  (having an outsole  52 ) of the men&#39;s shoe  50  without a heel.  FIG. 11B  is an exploded perspective view of the footwear base  51 , the shoe midsole  10  and the insole  54 .  FIG. 11C  is a back view of a situation where the shoe midsole  10  is covered with the insole  54  and fixed with an adhesive. 
     The footwear base  51  of the men&#39;s shoe  50  has the outsole  52 . The outsole  52  is the bottom of the shoe and is made of, for example, a high cushioning material such as polyurethane, etc. Moreover, the insole  54  is made of, for example, one sheet of leather. 
     According to this embodiment, the shoe midsole  10  is covered with the insole  54  and is integrally fixed to the insole  54 . Then, the shoe midsole  10  and insole  54  integrally fixed together are fixed on the outsole  52 . Namely, an upper surface  10   a , a side surface  10   c  and the outer circumference of a back surface  10   b  of the shoe midsole  10  are covered with the insole  54 , and they are integrally bonded together with an adhesive coated on the circumferential part of the insole  54  (see  FIG. 11C ). 
     Furthermore, the shoe midsole  10  and the insole  54  integrated together are integrally bonded to the outsole  52  by using an adhesive coated both on the circumferential part of the insole  54  and on the back surface  10   b  of the shoe midsole  10 . In this case, it is preferable that the shoe midsole  10 , the insole  54  and the outsole  52  are bonded together by applying a pressure to the portions to be bonded. In this way, the shoe midsole  10  is integrally bonded on the back of the insole  54 . As a result, the shoe midsole  10  is prevented from accidentally moving or coming off. 
     This embodiment refers to the case where the shoe midsole  10  and the insole  54  are bonded with the adhesive, and the insole  54  and the outsole  52  are also bonded with the adhesive. However, this embodiment is not limited to this implementation. For example, they may be stitched with a thread, or may be united with means such as welding, etc. Also this embodiment refers to the case where the shoe midsole  10 , the insole  54  and the outsole  52  are bonded together with the adhesive coated on the circumferential part. However, for example, they may be bonded by coating the adhesive on the whole region of the facing areas. Moreover, the adhesive may be coated between the circumferential part of the upper surface  10   a  of the shoe midsole  10  and the insole  54  so as to bond the shoe midsole  10  and the insole  54   
     This embodiment refers to the case where the shoe midsole  10  is covered with the insole  54 . However, this embodiment is not limited to this implementation. For example, the shoe midsole  10  may be bonded so that the side surface  10   c  of the shoe midsole  10  is exposed. 
     On the circumferential part of the insole  54 , a plurality of slits  54   a  are formed at nearly equal intervals. The slits  54   a  are intended to adjust the length of the outer circumference to that of the inner circumference within the circumferential part. On the upper surface of the insole  54  (the side opposite to the welding surface of the shoe midsole  10 ), a woven label  55  that displays the brand name of a manufacturer, etc. is stitched. 
       FIG. 12A  is an overall perspective view of the situation where the shoe midsole  10  is integrally fixed to the women&#39;s shoe  60  without a heel.  FIG. 12B  is an exploded perspective view of a footwear base  61 , the shoe midsole  10  and an insole  64 .  FIG. 12C  is a back view of the situation where the shoe midsole  10  is covered with the insole  64  and fixed together with an adhesive. 
     The footwear base  61  of the women&#39;s shoe  60  has an outsole  62  and a middle sole  63 . 
     The outsole  62 , the middle sole  63 , the insole  64 , a heel  66  and a woven label  65  are similar to those of the above described men&#39;s shoe  30 . Therefore, their descriptions are omitted. 
     According to this embodiment, the middle sole  63 , the shoe midsole  10 , and the insole  64  are integrally fixed in this order, and then the middle sole  63 , shoe midsole  10  and insole  64  fixed integrally are fixed on the outsole  62 . In this case, the back surface  10   b  of the shoe midsole  10  and an upper surface  63   a  of the middle sole  63  are united with an adhesive coated between them, and they are covered with the insole  64 . Namely, the upper surface  10   a  of the midsole  10 , the side surface  10   c  thereof, and the circumferential part of the back surface  63   b  of the middle sole  63  are covered with the insole  64  in the condition where the shoe midsole  10  and the middle sole  63  are united. Moreover, the shoe midsole  10 , insole  64  and middle sole  63  integrally united together are bonded with an adhesive coated on the circumferential part of the insole  64  and the back surface  10   b  of the shoe midsole  10  (see  FIG. 12C ). In this case, it is preferable that the shoe midsole  10 , the insole  64  and the middle sole  63  are bonded together by applying a pressure to their respective portions to be bonded. 
     Further, the middle sole  63  integrally united with the insole  64  and the shoe midsole  10  is integrally fixed to the outsole  62  with the adhesive coated on the back surface  63   b  of the middle sole  63  and the circumferential part of the insole  64 . 
     This embodiment refers to the case where the shoe midsole  10  and the middle sole  63  are bonded with the adhesive, and the middle sole  63  and the outsole  62  are also bonded with the adhesive. However, this embodiment is not limited to this implementation. For example, they may be stitched with a thread or united with means such as welding, etc. Alternatively, the adhesive may be coated between the circumferential part of the upper surface  10   a  of the shoe midsole  10  and the insole  64 , and then both of them are bonded. 
     The shoe midsole  10  is integrally bonded to the back side of the insole  64  in this way, thereby preventing the shoe midsole  10  from accidentally moving or coming off. This embodiment refers to the case where the shoe midsole  10  is covered with the insole  64 . However, this embodiment is not limited to this implementation. For example, the shoe midsole  10  may be bonded so that the side surface  10   c  of the shoe midsole  10  is exposed. 
     On the circumferential part of the insole  64 , a plurality of slits  64   a  are formed at nearly equal intervals. They are intended to adjust the length of the outer circumference to that of the inner circumference within the circumferential part of the insole  64 . Moreover, a woven label  65  is stitched on the insole  64 . 
     This embodiment refers to the case where the shoe midsole  10  is integrally fixed to the footwear base  51 ,  61  of the men&#39;s shoe  50  or the women&#39;s shoe  60 . However, this embodiment is not limited to this implementation. For example, the shoe midsole  10  may be integrally fixed to other footwears such as a sport shoe, a sneaker, a strapped or non-strapped sandal, a business shoe, a ski shoe, a golf shoe, a hiking shoe, a walking shoe, a boot, a long boot, an indoor shoe, a Japanese sandal, a slipper, a sock, etc. 
     According to this embodiment, the shoe midsole  10  is integrally fixed to the footwear base  51 ,  61  of the men&#39;s shoe  50  or the women&#39;s shoe  60 . Therefore, the shoe midsole  10  does not accidentally move or is not exposed. Therefore, it is not detected that the shoe midsole  10  is accommodated within the men&#39;s shoe  50  or the women&#39;s shoe  60  when viewed from the outside. With the shoe midsole  10 , which is integrally bonded to the footwear base  51 ,  61  of the men&#39;s shoe  50  or the women&#39;s shoe  60  in this way, the effects of shock absorption and massage for a sole of a foot during walking can be obtained for a long period. Similarly, a burden on a foot, a knee, etc. in a standing position can be reduced with the shoe midsole  10 .