Athletic shoe sole design and construction

Abstract: A midsole assembly for an athletic shoe comprises a midsole 3 formed of soft elastic material and extending from the heel portion to the forefoot portion of the shoe, a curved groove 34 formed on the bottom side of the forefoot region A of the midsole 3 and extending in the substantially lateral direction, a through hole 35 formed in the curved groove 34 and having an opening end on the plantar contact face of the midsole 3, and a cover portion 50 covering the curved groove 34. An air tube 36, which is formed of and surrounded by the curved groove 34 and the cover portion 50, has opening portions on both ends thereof. The cover portion 50 is integrally formed with the outsole 5.

Description: The present invention relates to a sole assembly for an athletic shoe, and more particularly, to a sole assembly having a through hole formed in a midsole. The sole of an athletic shoe is generally comprised of a midsole and an outsole. The midsole is typically formed of soft elastic material in order to ensure adequate cushioning properties. The outsole is fitted under the midsole and directly contacts with the ground. Preferably, ventilation of a shoe is secured in a degree when wearing a shoe. Various kinds of shoes with vent holes have conventionally been proposed. For instance, the Japanese patent application laying open publication No. 8-131204 discloses a plurality of transverse holes formed at a body portion of the bottom member of a shoe and a plurality of vertical holes also formed at a body portion of the bottom member. The vertical holes communicate with the transverse holes and penetrate through the insole. The Japanese utility model application examined publication No. 63-43923 shows a plurality of through holes penetrating through the upper member of a sole in the thickness direction and a plurality of grooves formed at the lower member of the shoe. Each of the grooves corresponds to each of the through holes. In both cases, the air flows into a shoe through the transverse holes and the vertical holes, or the through holes and the grooves. Thus, ventilation of the inside of a shoe is acquired. On the other hand, in an athletic shoe, especially in the case of a running shoe, a higher flexibility of the forefoot portion is required. In the prior art construction, however, transverse holes or grooves are merely formed on the body portion of the lower member made of rubber or the like. Thus, these transverse holes and grooves, which are made only in the light of ventilation, cannot satisfy higher flexibility that are required in an athletic shoe. US-A-5408761 discloses a sole assembly for an athletic shoe according to the preamble of claim 1 hereinafter. It is desirable to provide a sole assembly for an athletic shoe that can realize higher flexibility as well as ventilation of the forefoot portion of a shoe. The present invention provides a sole assembly for an athletic shoe comprising: a midsole formed of soft elastic material and extending from the heel portion to the forefoot portion of said assembly; a curved groove formed on the bottom side of said forefoot portion of said midsole and extending substantially in a shoe width direction; characterised by a through hole formed in said curved groove and having an opening end on the plantar contact face of said midsole; and a cover portion covering said curved groove, said curved groove and said cover portion creating an air tube. The air tube may be open at one end or at both ends. An openable and closable valve means may be provided at the opening portion of the air tube. The valve means may be formed of a projection or a protrusion at the bottom portion of the curved groove in the vicinity of the opening portion. Alternatively, the air tube may be closed at its both ends and an open air intake port communicating with the through hole in the curved groove may be formed at either the midfoot portion or the heel portion of the midsole. Also, the cover portion may be formed integrally with an outsole disposed on the bottom side of the forefoot portion of the midsole. As will be appreciated from the embodiments described hereinafter, in use of a shoe, the air is introduced or flows into the inside of the shoe through the curved groove and the through hole, and thus, ventilation can be acquired inside the forefoot portion of the shoe. Moreover, in this case, the thickness of the midsole is smaller at the curved groove formed portion, which causes the midsole to be easier to bend in the vertical direction along the curved groove, thereby improving flexibility or bendability of the forefoot portion. This improved flexibility can realize smoother transfer of the load and secure gripping properties when an athlete or a shoe wearer gets down onto the ground from the heel portion to the toe portion of the shoe. Furthermore, the opening portion of the through hole on the bottom side is prevented from being exposed to the ground by the cover portion. Thereby, water, sand, dust, and the like outside the shoe are blocked from entering the inside of the shoe via the through hole when the shoe contacts with the ground. In such a way, the shoe can be used as an outdoor shoe as well. When at least one end of the air tube is open, the open air is introduced into the curved groove through the opening end of the air tube and flows into the inside of the shoe via the through hole from the curved groove. When the openable and closable valve means is provided, the valve means closes the opening portion of the air tube at the time of bending of the forefoot portion, thereby increasing the air pressure inside the air tube. The pressure increased air in the air tube easily flows into the inside of the shoe via the through hole, which improves ventilation of the shoe. When a projection or protrusion is provided in the curved groove, it contacts with the cover portion at the time of bending of the forefoot portion, thereby closing the opening portion of the air tube. In this case, because the valve means is formed of a mere projection or protrusion, the structure of the valve means can be simplified. When both ends of the air tube are closed, the air pressure inside the air tube easily increases at the time of bending of the forefoot portion and the pressure increased air is pushed out of the through hole and flows into the inside of the shoe. In this case, the open air is introduced into the air tube through the intake port formed at the midfoot portion and/or the heel portion of the midsole. Thus, the supply of air to the air tube can be conducted with ease. Additionally, integral formation of the cover portion with the outsole can simplify the whole structure of the sole. For a more complete understanding of the invention, reference should be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention. In the drawings, which are not to scale: FIG. 1 is a lateral side view of an athletic shoe (left shoe) incorporating a sole assembly according to an embodiment of the present invention; FIG. 2 is a bottom view of the left shoe sole assembly in Fig. 1; FIG. 3 is a lateral side view of the sole assembly of FIG. 2; FIG. 4 is an enlarged view of a portion of FIG. 3; FIG. 5 is a cross sectional view of FIG. 2 taken along line V-V; FIG. 6 is a perspective view of the upper midsole of the sole assembly of FIG. 2, showing a corrugated sheet fitted on the bottom side of the upper midsole; FIG. 7 shows an alternative embodiment of FIG. 4; FIG. 8 is a schematic illustrating the action of the valve means of FIG. 7; and FIG. 9 shows an alternative embodiment of FIG. 2. Turning now to the drawings, FIG. 1 illustrates an athletic shoe incorporating the sole construction, or assembly, of an embodiment of the present invention. The sole of this athletic shoe 1 comprises a midsole 3, a corrugated sheet 4 and an outsole 5 directly contacting with the ground. The midsole 3 is fitted to the bottom of an upper 2. The corrugated sheet 4 having a wavy configuration is interposed in the midsole 3. The outsole 5 is fitted to the bottom of the midsole 3. The midsole 3 is provided in order to absorb impact load imparted on the bottom of the shoe 1 when an athlete lands on the ground. The midsole 3 is comprised of an upper midsole 3a and a lower midsole 3b that are respectively disposed on the top and bottom surfaces of the corrugated sheet 4. That is, the corrugated sheet 4 is interposed between the upper midsole 3a and the lower midsole 3b, and the sheet 4 is integrated with the upper and lower midsoles 3a, 3b. Also, the upper midsole 3a extends from the heel portion to the forefoot portion of a shoe 1, whereas the lower midsole 3b is disposed mainly at the heel portion. The midsole 3 is generally formed of soft elastic material having good cushioning properties. Specifically, thermoplastic synthetic resin foam such as ethylene-vinyl acetate copolymer (EVA), thermosetting resin foam such as polyurethane (PU), or rubber material foam such as butadiene or chloroprene rubber are used. The corrugated sheet 4 is preferably formed of thermoplastic resin such as thermoplastic polyurethane (TPU) of comparatively rich elasticity, polyamide elastomer (PAE), ABS resin or the like. Alternatively, the corrugated sheet 4 is formed of thermosetting resin such as epoxy resin, unsaturated polyester resin and the like. The corrugated sheet may be formed of a plate made of elastic metal, or a meshed sheet made of elastic metal fibers. At the contact portions of the midsole 3 with the corrugated sheet 4 are formed a plurality of transverse holes 6, 7 extending laterally (into the page of FIG. 1). These holes 6, 7 are provided for improving cushioning properties of the midsole 3 and decreasing its weight. As shown in FIGS. 2 and 3, a curved groove 34, which extends substantially laterally, or in the general shoe width direction, is formed on the bottom side of the forefoot region A of the upper midsole 3a. A plurality of vertically extending through holes 35 are formed in the curved groove 34. The through holes 35 are open on the plantar contact face 30 of the upper midsole 3a, shown in FIGS. 5 and 6. The curved groove 34 is covered with the resin mold cover portion 50, which is integrally formed with the outsole 5, mentioned hereinafter. The space surrounded by the curved groove 34 and the cover portion 50 creates an air tube 36, as is clearly seen in FIG. 4. Both ends of the air tube 36 are open at the medial and lateral sides of the shoe. Preferably, the cover portion 50 has a bent shape toward the bottom face of the curved groove 34 so that the cover portion 50 can return to its original position with ease after bent deformation of the forefoot portion of the shoe. A plurality of grooves 33 communicating with the through holes 35 in the curved groove 34 are formed at the forefoot region A of the upper midsole 3a. A vertically extending through hole 31 is formed at the midfoot region B, or the plantar arch portion, of the upper midsole 3a. At the opening portion of the through hole 31 on the bottom side is formed a concave portion 32, or a recess, in communication with the groove 33. The corrugated sheet 4 extends from the heel region C to the midfoot region B, or a plantar arch portion, of the midsole 3, and it is comprised of a heel portion 4a having configuration and a generally planar midfoot portion 4b formed integrally with the heel portion 4a. The broken line extending in the lateral direction at the heel portion 4a of FIG. 2 shows a crest or a trough of corrugation of the corrugated sheet 4. As shown in FIGS. 2 and 6, the recess 32, which is formed at the midfoot region B of the upper midsole 3a is covered with the midfoot portion 4b of the corrugated sheet 4 and the midfoot portion 4b is formed with a slit, or air intake port 42, which is oppositely disposed to the recess 32, but not to the through hole 31. The outsole 5, shown in FIGS. 2 and 3, is comprised of a heel portion 5a placed on the bottom face of the lower midsole 3b and forefoot portions 5b and 5c that are placed mainly on the forefoot region A of the upper midsole 3a. The heel portion 5a is separated from the forefoot portions 5b, 5c. The forefoot portions 5b, 5c are integrated with each other by the cover portion 50 extending along the curved groove 34. In use of the shoe, the air, which has been introduced into the air tube 36 from the opening portions 34a, 34b on the medial and lateral sides, flows into the inside of the shoe via the through holes 35, thereby acquiring ventilation of the forefoot portion inside the shoe. Also, the air, which has been introduced into the recess 32 of the upper midsole 3a from the slit 42 of the corrugated sheet 4, flows into the midfoot region B inside the shoe via the through hole 31 and flows into the through hole 35 as well via the groove 33. Moreover, in this case, the thickness of the upper midsole 3a is made smaller at the curved groove 34 compared to the other portions of the midsole 3a, which facilitates bending of the upper midsole 3a in the vertical direction along the curved groove 34, thereby improving flexibility, or bendability, of the upper midsole 3a. Also, improved flexibility of the upper midsole 3a allows for smoother transfer of the load and secures gripping properties when an athlete lands on the ground from the heel portion to the toe portion of the shoe. Furthermore, the opening portion of the through hole 35 on the bottom side is prevented from being exposed to the ground by the cover portion 50. Thereby, water, sand, dust, and the like outside the shoe are blocked from entering the inside of the shoe via the through hole 35 when the shoe contacts with the ground. In such a way, the shoe can be used as an outdoor shoe. Also, in this case, because the cover portion 50 is integrally formed with the forefoot portion 5b, 5c of the outsole 5, the whole shoe structure can be simplified. In addition, when the cover portion 50 is formed of the transparent resin, the through hole can be seen from the bottom side of the shoe, which can improve aesthetic impression. In another embodiment, a valve member, which can open and close the air tube 36, may be employed at the opening portions 34a, 34b on both sides of the curved groove 34. FIG. 7 shows such a valve member of the sole construction. In FIG. 7, a projection or a protrusion 37 is formed on the bottom side of the curved groove 34 in the vicinity of the opening portion and each of the opening portions 34a, 34b of the curved groove 34 is narrower compared to the above-identified embodiment shown in FIGS. 1-6. When the forefoot portion of the shoe bends from the condition shown in FIG. 7, the upper midsole 3a is bent and deformed into the shape shown in FIG. 8. Then, the protrusion 37 comes in contact with the cover portion 50 and the opening portions 34a, 34b are forced to be closed, which increases the air pressure inside the air tube 36. The pressure increased air in the air tube 36 easily flows through the through hole 35 and into the inside of the shoe, thereby advancing ventilation of the shoe. Additionally, the groove 33 formed in the upper midsole 3a may be omitted in the embodiments shown in FIGS. 1-8. Because the open air can flow into the curved groove 34 mainly through the opening portions 34a, 34b on both sides of the curved groove 34 rather than through the groove 33. In such a way, the air can be supplemented into the air tube 36. In still another embodiment, one end or both ends of the curved groove 34 may be tightly closed. FIG. 9 shows such a curved groove 34 one end of which is closed, or not open. At the time of bending of this forefoot portion, the air pressure in the air tube 36 easily increases, thereby allowing the pressure increased air in the air tube 36 to smoothly enter the inside of the shoe via the through hole 35, which can improve ventilation of the shoe. In this embodiment as well, the valve member shown in FIG. 7 may be employed at the opening portion 34a of the curved groove 34. Thus, improved ventilation can be acquired. On the other hand, when the both ends of the curved groove 34 are closed, or not open, the air is supplemented into the air tube 36 through the slit 42 of the corrugated sheet 4 to the recess 32 and through the groove 33 of the upper midsole 3a. The recess 32, or concave portion, communicating with the groove 33 may be formed on the heel region C of the upper midsole 3a. In this case, the slit 42 corresponding to the recess 32 is formed on the heel portion 4a of the corrugated sheet 4. When the slit 42 is provided on the forefoot portion 4b or the heel portion 4a of the corrugated sheet 4, the position of the slit 42 is placed at a concave portion located away from the ground contact face of the shoe. Thus, water, sand, dust, and the like outside the shoe are prevented from entering the slit. The cover 50 is preferably integral with the outsole 5, but it can be separated from the outsole 5. Those skilled in the art to which the invention pertains may make modifications and other embodiments upon considering the foregoing teachings. The described embodiments and examples are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. Consequently, while the invention has been described with reference to particular embodiments and examples, modifications of structure, sequence, materials and the like would be apparent to those skilled in the art, yet still fall within the scope of the invention as defined in the accompanying claims.

Claims: A sole assembly for an athletic shoe comprising: a midsole (3) formed of soft elastic material and extending from the heel portion (C) to the forefoot portion (A) of said assembly; a curved groove (34) formed on the bottom side of said forefoot portion of said midsole and extending substantially in a shoe width direction; characterised by a through hole (35) formed in said curved groove and having an opening end on the plantar contact face (30) of said midsole; and a cover portion (50) covering said curved groove, said curved groove and said cover portion creating an air tube (36). A sole assembly of claim 1, wherein said air tube (36) has an opening portion (34a,34b) at least at one end thereof. A sole assembly of claim 2, wherein a valve means is provided to open and close said opening portion (34a,34b) of said air tube (36). A sole assembly of claim 3, wherein said valve means is comprised of said cover portion (50) and a projection or a protrusion (37) formed at the bottom portion of said curved groove (34) in the vicinity of said opening portion (34a,34b). A sole assembly of claim 1, wherein both ends of said air tube (36) are closed and an open air intake port (42) communicating with said through hole (35) in said curved groove (34) is formed at least either at a midfoot portion (B) or at said heel portion (C) of said midsole (3). A sole assembly of claim 1, wherein said cover portion (50) is integrally formed with an outsole (5) that is disposed on the bottom side of said forefoot portion (A) of said midsole (3). An athletic shoe comprising a sole assembly as claimed in any one of claims 1 to 6.

Inventors: KITA KENJIRO, KITA, KENJIRO
Applicants: MIZUNO KK, MIZUNO CORPORATION
Application year: 2000
Main classification: A43B7
IPC codes: A43B13, A43B7