CA2075989A1

CA2075989A1 - Article of footwear having improved midsole

Info

Publication number: CA2075989A1
Application number: CA002075989A
Authority: CA
Inventors: Hy Kramer
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-02-09
Filing date: 1991-02-04
Publication date: 1991-08-10
Also published as: FI923565A; RO109029B1; HU9202576D0; EP0594589B1; GR910100070A; PL289003A1; KR920702948A; ATE185951T1; YU20891A; CZ280447B6; EP0594589A1; WO1991011928A1; PL167270B1; FI923565A0; EP0594589A4; KR0148225B1; BR9106003A; IN175339B; JPH05503451A; CS31791A3

Abstract

A midsole, partial midsole, or the like (10), for inclusion in an article of footwear having a flexible, air-permeable top sole, characterized by at least one plug (11) in the heel region having a thickness (height) sufficient to permit significant compression deformationm along its thickness dimension accompanied by simultaneous significant bulging deformation in its circumscribing surface perpendicular to the thickness dimension; the deformations occuring solely due to normal walking activity by any wearer of the footwear; and the deformations thereby providing simultaneously for shock-absorption and ventilation during said normal walking activity.

Description

2 ~ rl 3 l~ ,Q 9 ~/0 91/1 1928 PCr/US9~/OU~90 ARTICLE OF FOOl~WEAR HAVI~G IMPROVED MIDSOLE

BACKGROUND OF THE INVENTION
1. Fi~ld o~f the Invention The present invention relates to improved article~ of footwear, particularly shoes having improved step cu~hioning and ventilation of the foot of the wearer. More particularly ~till, it relates to improvements in midsoles.
2. Backaround Art A large number of sport shoes such aq running shoes have been disclo~ed in the art and many are on the market, displaying variouR forms of midsole for the purpose of improving the performance of athletic shoes. Many ~haped outsoles, which are the only portions which actually contact the ground, have been proposed to provide shock ab~orption features.
Many items of prior art are known, such as U.S. Patent No.
4,782,603 issued November 8, 1988 to S.C. Brown. This patent provides a separate molded mid~ole encap~ulating a ~eries of parallel, spaced-apart tube~, disposed in a generally transverse po~i~ion with regard to the length of a shoe. The parallel tubes are subject to compres~ion with the step of the wearer, and the patent states that the tubes must be of suficient re~iliency and strength to resi3t collap~e along their walls.
U.S. Patent No. 49316,332 is~ued February 23, 1982, to Giese et al shows an outsole with hollow portion~ adapted to retain a shock absorbing materlal, and surrounded by a comparatively hard rim portions of the outsole.
U.S. Patent No. 4,608,768 i~ u~d September 2, 1986, to Cavanagh discloses the u~e of plug~ which are in~erted in an openwork ~upport forming a mid~ole. The plugs are made of a material ~hat i8 harder than that of the mid~ole.
U.S. Patent No. 4,831,749 is~ued May 23, 1989, to T~ai disclo~e~ a footwear including a ventilating and ma~saging insole having a plurality of uppar beads protruding upwardly to touch ~ -a wearer'~ ~oot and a plurality of lower bead~ protruding downwardly to ride on a footwear sole ~o that upon a depre~sion of a wearer's foot on the in~ole, an air flow will be pumped through holes each hole formed between each upper bead and each :' : : -' . . -,, ~' . ~ ., ' . .

WO~1/1192g 207~ 33 PC'r/~1991/00590 lower bqad for ventilating the wearer ~ foot and for massaging the 8 ame .
U.S. Patent No. 4,685,224 is~ued Augu~t 11, 1987, to Anger di~clo~e~ the use of a labyrinth of ventilation channel~ between the top-sole of a ~hoe and the under~ide of the foot. This i8 intended to provide a pumping effect to move air around and ventilate the foot of the wearer.
U.S. Patent 3,418,731 issued December 31, 1968, to Anciaux discloses the use of an insole for a shoe provided with upper and lower surface~ of resilient material, and the upper surface of the sole being provided with a plurality of blind reces~es, and the bottom surace being provided with corresponding projections so as to provide some ventilation during the action of walking.
The apparently closest background art encountered in the preparatory ~earch is U.S. Patent 4,845,863 i~Yued July 11, 1989, to Lin Yung-Mao which disclose~ the uae of an insole or mid~ole in an active wear shoe. The specification deal~ with an impermeable midsole/insole con~truction with downwardly projecting resilient member~, with those members being so placed and sized a~ to fit into receptables in the outsole to cuqhion the step of a wearer. The patent desc~ibes prior art deficiencies a follows:
Thus, conventional mid~ole~ do not offer anything in the way of independent ~u~pen~ion or deformation of various areas thereof, and further are ~uited to only a particular wei~ht class or cushionability preference of wearers.
The need for a midsole having a plurality of cu~hioning elements, each demon~trating an individual suspen~ion and deforming independently from the remaining elements has generally been met by the custom mid~ole aB di~closed in U.S. Patent No.
4,733,483, March 29, 1988, to Lin. However, it ha~
been found that a flat out~ol~ and mid~ole as di~closed therein have a tendency to creata a springboard effect which cau3es the heel to bounce and vibrate. Unle~s the midsole fits perfectly into the ~091/ll92X 2 ~ 7 ~ ~ ~ 9 PCT/us91/no5~) cavity created within the shoe, there i~ also a tendency for the midsole to ~lip therein. Thus, a need has arisen for a midsole that has a plurality of cu~hioning elements with individual suspension that doe~ not 91ip or vibrate.

Related U.S. Patent 4,843~741 issued July 4, 1989, also to Lin Yung-Mao, disclose~ similar structures, but additionally the downwardly depending plugs are provided with generally cylindrical cavitie3 in each element, for the purpo~e of reducing the waight of the midsole.
For further background material, the reader i~ directed to an article in New Sci~ntist of 15 July, 1989, by Alison Turnball "A Race for a Better Ru~ning Shoe", pages 42-44, and the immediately following article "How Elastic i~ a Running Shoe?"
by Alexander an~ Bennett, pagas 45 and 46. The authors discu2~ed a recent trend in athletic ~hoe manufacture which aims to return to the runners some of the energy expended in taking each step. Many di~closure~ in the prior art are directed at means for achieving some return of energy in this fashion.
Alexander and Bennett s~m up their test results as follows:
The quality to look for in a shoe g heel is probably high complianc~ (or peak deformation), which -will reduce the forces of impact. Looking at the same thing in a different way, ~he hsel ~hould be able to abs~rb the foot ~ kinetic ~nergy without developing ~ -large forces, 80 large value3 in "peak deformation" :. --and "work of deformation" are probably good.
High energy return in the ~or~part of the ~ole doe~ seem po~entially important (~e~ Table 3). But the figures ~rom our te~t~ ~or the percentage of energy returned still do not tell U9 how much energy a shoe returns. For that, we need to know how much energy wa ~tored in the fir~t place. The higher the compliance (or peak deformation) and the work of deformation, the more energy the ~ole stores as it is .. . . . . . .

.~ :

WVg~ 928 2 ~ ~J 9 ~J J PC~/I,SlJ1/~59~) compres~ed. The higher the energy return, the more of that energy i~ recovered in the elastic recoil.
SUMMARY OF THE INVENTION
The pre~ent invention i8 not directed to an objective of maximizing, or even obtaining, energy return to the walkers, but to the objective of shock-absorbing relatively gentle shock~ of the steps of a normal walker and simultaneously ventilating the inside of the shoes worn~
In order to achieve thi~ objective, it wa~ found that an extremely soft material mu~t be used for the pluy~ or col~lmn~ of the pre~ent invention and that ~uch plug~ or columns must either point upwardly underneath a permaable and flexible top sole (sometimes called insole and socksole) or point downwardly from such top-~ole, and ju~t a~ importantly that ~uch columns bulge significantly when compressed by the stepping action of a normal walker. The bulging action moves the air between the columns, thus ventilating the article of footwear and the foot through the to~-sole. The softnes~ of column material en~ures a large value in "peak deformation" for a small value in "work of deformation."
It has been found, that ~uch footwear is beneficial to the walker s joints and spinal column, in addition, of cour~e, to the wearer' 8 feet.
The pre~ent invention provides an article of footwear which includes in the ~ole area a number of vertical plug or columns adapted to ea~ily compres~ and bulge with ea h ~tep of the wearer. Thi8 provide~ a ~hock-absorbing element of special value as it provides a comfortable ba~e for the foot, fairly conformable to it8 801e contourY, and cushion~ each step of the wearer. The compre~sibility of the thermopla~tic material i~
such that the plug~ are compre~sed and ~ignificantly deformed to cu~hion each step of the wear2r, the deformation being accompanied by substantial bulging of the plugs, and the compres~io~, bulging9 and ~ub~equent recovery of the shape of the plug~ providing ~ignificant flow of air in the sole region, for ventilatin7 the article of footwear.

.

'091/1]928 ~ ~ 7 ~ .~ 8 9 PCT/~S91/0~;90 On~ embodiment of the pre~ent invention provides a midsole or part mid~ole adapted for inclusion in an article of footwear, to provide atep cushioning and ventilation for the wearer. The midsole or part midsole comprises a web portion adapted to extend along at least a portion of an out~ole of the footwear and includes a cuqhioning element compri~ing a plurality of plug~ projecting perpendicularly with respect to the plane of the web. Each plug is made of elastic but easily compressible thermoplastic rubber or the like. The plugs are diqtributed on a web B0 aq to provide a comfortable ba~e ~or the foot of a wearer to cushion each step of the wearer. The distribution, size and number of the plug~, and the compres~ibility of the material iB such that the plugs are easily deformed and significantly compres~ed to cu~hion each step of the wearer, the compression being accompanied by sub3tantial bulging of the plug. The compression, bulging, and subsequ~nt recovery of the shape of the plug provides movement of the surrounding air, for ventilation of the article of footwear.
In another embodiment, the invention provide~ an article of footwear compri~ing an out~ole and an upper, the outsole being provided with a plurality of upstanding plugs formed of resilient easily compressible material. The plugs are distributed on the outsole 80 as to provide a comfortable base for the foot of a wearer, and to cu~hlon the ~teps of a wearer.
Tha distribution, size and n~mber of said plug~ and the compres~ibility of th~ plastic ~s auch that the plugs are deformed and aignificantly compras~ed to ~ushion each s~ep of the wearor, the compres3ion being accompanied by sub~tantial bulging o~ the plug. The compression, bulging, and ~ubsequent recovery of the shape of the plug providing a ~ignificant flow of air along the outsole, for ventilation of the article of footwear.
BRIEF DESCRIPTION OF TEE DRAWINGS
The preferred embodiment~ of the pre~ent invention will now be described in detail in conjunction with the annexed drawings, in which:

WO91/1192~ 2 0 7 3 ~fl PCT/~S91/005g~

FigurQ 1 show~ a plan view of a midsole manufactured in accordance with a preferr~d embodiment of this invention;
Eigure 2 show~ a perspective view of a portion of a web shown in Figure l;
Figures 3, 4, and 5 are side elevation~ of a portion of web as ~hown in Figure 2, illustrating three embodiments of the upstanding plugs of the invention;
Figure 6 hows a different embodiment of a web, provided with a sock-sole;
Figure 7 shows a cut-away view of a complete shoe embodying one aspect of this invention;
Figure 8 shows a further embodiment of the inventive concept employing the compressible plugs;
Figure 9 shows an out301e provided with cavitie~ or ~paces for in~tallation of partial midsole 8eCtions of the type shown in Figure 2;
Figure~ 10 and 11 ~how ections of web 3uch as shown in Figure 2, with variationa in the shape of the plugs;
Figure 12 ~how~ a toe portion 41 of a web a3 shown in Figure 9, ln which the forwar~most plugs 53 are ~omewhat progressively shorter in length to ~uit a spacific installation;
Figure 13 show~ a variation of the invention;
Figure 14 shows a partial midsole conRtruction in the heel of a shoe according to the present invention; and Figure 15 show~ a variation of the present invention as applied to the heel of a women'~ shoe or sandal.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With referenc~ to Figure 1 of the drawingY, it ~ho~s a plan view of a mid~ole shown generally a~ web 10 which i8 provided with a large number of upstanding plug~ 11. The~e plugs are dispo~ed in thi~ embodiment along the entire midsole 10, which extends from the toe portion 12 through the ball portion 13 to t~e heel portion 14. In thi embodiment each plug 11 is up~tanding with respect to the web 10, and i9 affixed to the web at its proximal end. Each plug 11 in thi~ embodiment di~plays a central aperture 16.

,, .

09l/11928 ~ ~ 7 ~ PCT/US~l/00~90 The entire midsole 10 i8 preferably manufactur~d by injection moldins, in which case the web 10 of the midsole a~
well as ~he pLugs 11 are of the same material, and in which case the web 10 is highly flexible but not air-permeable. Such midsole then would be suitable for inclusion in an article of footwear, where the web 10 i~ in contact with the top of the out~ole and the plugs 11 pro~ect upwardly.
The most ~uitable material found for such mid~ole is that known a~ "Super~oft" thermopla~tic resin available from GLS
PLASTICS of Woodstock, IL 60098, U.S.A. ~sold by them under item #G3294). The material is made from a thermoplastic compound known as "Kraton"~ supplied by the Shell Chemical Company. The preferred Kraton compound3 ~because they are softest having Shore A hardnes~ [D-2240] o~ 27 and 34~ are Kraton D-2104 and Kraton D~3226.
The re ulting Supersoft thermopla~tic yield~ a midsole material having Durometer readings ~elow 30, and preferably in the vicinity of 20. In spite of the softnes3 of the resultant midsole, it still exhibits excellent elasticity and long life.
Of cour~e, there are o~her material3 besides Kraton, such as Estane, polyvinyl chloride or rubber. The requi~ite characteri3tics of ~he material is that they yield plugs 11 that are ea ily compressible and significantly ~eformable ~generally having Durometer reading~ below appr. 30) but that have long life and good ela~ticity in order to spring back to their original ~hape onca compres~ive forces have been re~oved. The ~hape of the plug3 11 is not critical, and whether they are hollow or solid does not generally affect their deormability.
In the embodiment of Figure 1 they are made hollow in order to save thermoplaatic re in.
Turning now to Figures 2 and 3, these show portions of the midsole shown in Figure 1 in perspective view and s~de elevation r~pectively. In Figure 3 it can be seen that thi~ embodiment i~ provided with lower projection~ 20, which provide a small amount of ventila~ion below the midsole. In Figure 4 the plugs are shown as item~ 20 and 21. It will be ~e~n that in the embodiments shown in Eigure 4, the plug~ are of varying ,, . , ~ :

, WO ~1/11928 ~ ~3 7 ~ 3 ~ ~ Pcr/ussl/oo~so thi~kne~ (i e., height). Such thickness or height i~ of course diqcretionary, but values below 10 mm would appear reason~ble.
In Figure 5 it will be seen that the plugq 22 are held in place in the mid~qole by a web 10 which i9 centrally located with respect to the plugs 22. This, of course, adds to cushionability of shocks.
In Figures 3, 4 and 5, the central aperture-q 16 are Rhown in plugs 11, 20, 21, and 22 aR dotted lines.
Figure 6 shows an embodiment in which a portion of midsole as shown in Figure 3 is provided with a top web 25, which suitably can be prepared of porous material, or it can be a perforated material, thereby providing for Rome movement of air.
In thi~ figure, the plugR 11 are ~hown compressively deformed and bulging.
Figure 7 ~hows a cut-away view of a shoe embodying on~ form of the present invention, in which the midsole shown in Figure 1 is in place on top of outsole 31 in a shoe. A flexible, air-permeable top-sole 30 i~ in place over the midsole.
Figure 2 ~hows a variation whersin the outsole 31 in the embodiment shown in Figure 7 i8 replaced by outsole 32, which i8 provided with a multipli~ity of pockets 33 adapted to receive and retain plugs 11 of the type discu~ed above, thus eliminating ~he need ~or the web 10 to retain these plug~ in place. Plugs 11 may be retained permanently in hole~ 33 by adheRion means, or any other suitable means.
Figure 9 show~ an embodiment wherein an out~ole 42 i8 provided during manufacture with cut-away portion~ 43 and 44 ~o that ~uit~bly sized and shaped ~ectiona 40 and 41 of web such as shown in Figure~ 2, 3, etc., fit directly into the qpace3, thereby takin~ up less v~rtical room in the interior of the footwear. The web section~ 40 and 41 compri~ing the "midsole"
are also thus held effectively in place against lateral movement. It i8, of cour~e, po~sible to provide only one of the s~ctlons 40 and 41.
Figure 10 illustrates an embodiment of the invention in which a ~ection of the web 10 ~uch a~ shown in Figure 2 i~
provided with plugs 50, which are ~olid plug_ inqtead of the , , '091/1192X 2 fJ 7 ,~ n~ ~ 9 PCr/US~1/00590 hollow plugs 11 ~hown in Figure 2. It may be necessary to u3e even qofter material for the plugs 50, in order to maintain the desired high degre~ of compre~ ility, yi~lding a suitable extent to compression under the ~tep of a wearer, while allowing the plug to bulge, and recover.
Figure 11 show3 still another embodiment of the present invention in which a portion of the web 10 similar to that in Figure ~ i8 provlded with up~tanding plugs 51 which are hollow, but essentially s~uare in cross section. These various deqign parameters may be varied in order to achieve a maximum performance. Such variables as the resiliency of the plastic material, the height and ~hape of the plug~, the distribution and number of the plugs per unit of area, variations in the height~ of variou8 plug~, or row~ of plug~, hollow versu~ solid plugs, and the thickne~s of the walls in such hollow plugs, can all be varied for the purpose of achieving the objectives of the pre~ent invention. Satisfactory re~ult~ hav~ been obtained using plugs having a cross-sectional area of appr. 0.5 cm2 with a wall thickneqs of 1 to 3 mm if holiow.
Figure 12 ~hows a further variation of the invention, in which the plugs are not all of the same length, wherein in insert 41 similar to the one ~hown in Figure 9, for the toe portion of a ~hoe or ~andal, as may be seen from Figure 12, the plugs 11 grow progressively ~hor er through plugs ~2 to 53 a~
they approach the toe. The lengths of the plug8 may be ~aried in any suitable manner to accommodate the geometry of the inside of the item of footwear.
Figure 13 show~ a further embodiment of a portion of a web in accordance with the present invention, wherein the plug~ in the upper and lower webs are facing each other for added cushioning. Again, the upper web should be flexible and preferably al80 air-permeable.
In Figure 14, the inner part of a heel section 60 of an outsole or mid~ole is ~hown which ha~ a square rece~s 61 in it.
The rece~s 61 ha~ inserted therein a single large diameter cylindrical plug 62 which is shown in it~ fully compressively deformed position for explanatory purposes. A~ may be seen, the WO~ Jg28 2B7 ~-J5'i PCT/~Sgl/005~0 compre~lv~ deformation i 9 causing the plug 62 to bulge but, of course, only to partially fill in the space between it3 circumfor~nce and the corner~ of the racess 61, thus pumping air upwards every time the plug 62 bulges.
In Figure 15, a heel section 70 of a women 8 shoe or sandal is shown, which ha~ shown in it, for purposes of explanation, cylindrical rece~e0 71 and rectangular recess 72. Of course, any other polygonal rece~ may be u~ed. Plugs 73 and 74, when installe~ in the rece~se~ stick out as desired due to the recesses being shallower than the thickness or length of the plug9 .

Claims

1. An article of footwear comprising at least one solid cylindrical plug made of a highly and easily compressible material, said plug supported by fitting in a rectilinear recess in the heel of said article of footwear and protruding upwardly therefrom to cushion the steps of its wearer by compressively deforming and simultaneously bulging to fill in spaces between its circumference and corners of said rectilinear recess thereby evacuating air in said spaces upwardly to ventilate the wearer's foot.

2. An article of footwear as defined in claim l, said at least one plug being under a flexible, air-permeable top-sole in said article of footwear.

3. An article of footwear as defined in claim 2, said rectilinear recess being rectangular.

4. An article of footwear as defined in claim 3, said rectilinear recess being polygonal.

5. An article of footwear as defined in claims l, 2 or 3 said article of footwear comprising a plurality of smaller plugs substantially evenly distributed over the heel area.

6. An insert for an article of footwear comprising:
- a web;
- a plurality of plugs integral with said web and extending vertically from at least one side of said web;
- said plugs comprised of a resilient, compressible thermoplastic material having a Shore A (D 2240) hardness value of less than about 35;
- said plugs having a height in the range of from about 3 mm to about 10 mm; and - said plugs being sufficient in number and design to permit significant compressive deformation along their height dimension accompanied by simultaneous significant bulging deformation in the circumscribing surface perpendicular to the height dimension when said insert is in use to provide for shock absorption and ventilation.

7. The article of claim 6 wherein an air permeable top sole overlies said plugs.

8. The article of claim 6 wherein said thermoplastic material has a Shore A (D-2240) hardness value of about 20.

9. The article of claim 6 wherein said plugs are hollow.

10. The article of claim 9 wherein said plugs are cylindrical.

11. The article of claim 6 wherein said plugs are solid and cylindrical.

12. The article of claim 6 wherein said web is sole shaped and flexible to closely conform to the contour of a shoe.

13. The article of claim 12 wherein said plugs vary in height such that the plugs in the toe portion of said article are shorter than the remaining plugs.

14. The article of claim 6 wherein said web is shaped to conform to the heel of a shoe.

15. The article of claim 6 wherein said thermoplastic material is selected from the group consisting of Kraton D-2104, Kraton D-3226, Estane , polyvinyl chloride, and rubber.

16. The article of claim 6 wherein said plugs vary in height.

17. An article of footwear comprising an outsole, a midsole and an uppersole wherein said midsole comprises:
- a web;
- a plurality of plugs integral with said web and extending vertically from at least one side of said web;
- said plugs comprised of a resilient, compressible thermoplastic material having a Shore A (D-2240) hardness value of less than about 3 5;
- said plugs having a height in the range of from about 3 mm to about 10 mm; and - said plugs being sufficient in number and design to permit significant compressive deformation along their height dimension accompanied by simultaneous significant bulging deformation in the circumscribing surface perpendicular to the height dimension when said insert is in use to provide for shock absorption and ventilation.

18. An article of footwear as set forth in claim 17 wherein said top sole is comprised of air-permeable material overlying said plubs.

19. An article of footwear as set forth in claim 17 wherein said plugs vary in height.