U.S. patent application number 16/695703 was filed with the patent office on 2020-05-28 for sole structure for an article of footwear.
The applicant listed for this patent is NIKE, Inc.. Invention is credited to Margarita L. Cortez, Fred G. Fagergren, Klaas P. Hazenberg, Eric S. Schindler, Camden D. Stanke.
Application Number | 20200163409 16/695703 |
Document ID | / |
Family ID | 48916241 |
Filed Date | 2020-05-28 |
View All Diagrams
United States Patent
Application |
20200163409 |
Kind Code |
A1 |
Cortez; Margarita L. ; et
al. |
May 28, 2020 |
Sole Structure for an Article of Footwear
Abstract
A sole structure for an article of footwear includes one or more
outsole portions. At least some of these outsole portions include a
plurality of alternating upward-facing and downward-facing elongate
channels. The channels may have a base and two sidewalls, with
adjacent channels sharing a common sidewall. The bases of the
downward-facing channels form an upper surface of the outsole
portion and the bases of the upward-facing channels form a lower
surface of the outsole portion. The sidewalls are arranged at
non-perpendicular angles to the upper surface. A first outsole
portion has a pressure-versus-strain curve having a local maximum
at a "trip point" pressure value and a first strain value and
wherein the pressure-versus-strain curve has a change in strain of
at least approximately 10% before a second occurrence of the "trip
point" pressure value is reached. An article of footwear having the
sole structure attached to an upper is also provided.
Inventors: |
Cortez; Margarita L.;
(Portland, OR) ; Fagergren; Fred G.; (Hillsboro,
OR) ; Hazenberg; Klaas P.; (Guangzhou, CN) ;
Schindler; Eric S.; (Beaverton, OR) ; Stanke; Camden
D.; (Portland, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIKE, Inc. |
Beaverton |
OR |
US |
|
|
Family ID: |
48916241 |
Appl. No.: |
16/695703 |
Filed: |
November 26, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15455229 |
Mar 10, 2017 |
10595588 |
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16695703 |
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13556872 |
Jul 24, 2012 |
9629415 |
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15455229 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A43B 5/10 20130101; A43B
13/188 20130101; A43B 13/223 20130101; A43B 5/06 20130101; A43B
13/186 20130101; A43B 5/02 20130101; A43B 13/04 20130101; A43B
13/122 20130101; A43B 13/181 20130101; A43B 13/184 20130101; A43B
5/002 20130101 |
International
Class: |
A43B 13/18 20060101
A43B013/18; A43B 13/22 20060101 A43B013/22; A43B 13/12 20060101
A43B013/12; A43B 5/00 20060101 A43B005/00; A43B 5/02 20060101
A43B005/02; A43B 5/06 20060101 A43B005/06; A43B 5/10 20060101
A43B005/10; A43B 13/04 20060101 A43B013/04 |
Claims
1. A sole structure for an article of footwear, comprising: one or
more outsole portions, a first outsole portion having: a plurality
of alternating upward-facing channels and downward-facing channels;
wherein each channel has a base element and two sidewalls, with
adjacent upward-facing channels and downward-facing channels
sharing a common sidewall, wherein the base elements of the
downward-facing channels form an upper surface of the first outsole
portion and the base elements of the upward-facing channels form a
lower surface of the first outsole portion, and wherein the
sidewalls are curved, and wherein adjacent sidewalls curve in
opposite directions.
2. The sole structure of claim 1, wherein the sidewalls are curved
such that the upward-facing channels have a convex configuration
and the downward-facing channels have a concave configuration.
3. The sole structure of claim 1, wherein the plurality of
alternating upward-facing channels and downward-facing channels
includes a first upward-facing channel and a first downward-facing
channel that share a first common sidewall, and wherein a thickness
of the first common sidewall increases in a direction downward from
the base element of the first upward-facing channel toward the base
element of the first downward-facing channel.
4. The sole structure of claim 1, wherein the plurality of
alternating upward-facing channels and downward-facing channels
includes a first upward-facing channel and a first downward-facing
channel that share a first common sidewall, and wherein a thickness
of the base element of the first upward-facing channel varies.
5. The sole structure of claim 1, wherein the plurality of
alternating upward-facing channels and downward-facing channels
includes: (a) a first upward-facing channel, (b) a first
downward-facing channel, wherein the first upward-facing channel
and the first downward-facing channel share a first common sidewall
on a first side of the first-upward facing channel, and (c) a
second downward-facing channel, wherein the first upward-facing
channel and the second downward-facing channel share a second
common sidewall on a second side of the first upward-facing channel
located opposite from the first side, wherein a thickness of the
first common sidewall increases in a direction downward from the
base element of the first downward-facing channel toward the base
element of the first upward-facing channel, and wherein a thickness
of the second common sidewall increases in a direction downward
from the base element of the second downward-facing channel toward
the base element of the first upward-facing channel.
6. The sole structure of claim 1, wherein the plurality of
alternating upward-facing channels and downward-facing channels
includes: (a) a first downward-facing channel, (b) a first
upward-facing channel, wherein the first upward-facing channel and
the first downward-facing channel share a first common sidewall on
a first side of the first-downward facing channel, and (c) a second
upward-facing channel, wherein the first downward-facing channel
and the second upward-facing channel share a second common sidewall
on a second side of the first downward-facing channel located
opposite from the first side, wherein a thickness of the first
common sidewall increases in a direction downward from the base
element of the first downward-facing channel toward the base
element of the first upward-facing channel, and wherein a thickness
of the second common sidewall increases in a direction downward
from the base element of the first downward-facing channel toward
the base element of the second upward-facing channel.
7. The sole structure of claim 1, wherein the first outsole portion
is located in a heel region of the sole structure.
8. The sole structure of claim 7, wherein the one or more outsole
portions incudes a second outsole portion located in a forefoot
region of the sole structure, the second outsole portion having: a
plurality of alternating upward-facing channels and downward-facing
channels; wherein each channel of the second outsole portion has a
base element and two sidewalls, with adjacent upward-facing
channels and downward-facing channels of the second outsole portion
sharing a common sidewall, wherein the base elements of the
downward-facing channels of the second outsole portion form an
upper surface of the second outsole portion and the base elements
of the upward-facing channels of the second outsole portion form a
lower surface of the second outsole portion, and wherein the
sidewalls of the second outsole portion are curved, and wherein
adjacent sidewalls of the second outsole portion curve in opposite
directions.
9. The sole structure of claim 1, wherein the one or more outsole
portions incudes a second outsole portion having: a plurality of
alternating upward-facing channels and downward-facing channels;
wherein each channel of the second outsole portion has a base
element and two sidewalls, with adjacent upward-facing channels and
downward-facing channels of the second outsole portion sharing a
common sidewall, wherein the base elements of the downward-facing
channels of the second outsole portion form an upper surface of the
second outsole portion and the base elements of the upward-facing
channels of the second outsole portion form a lower surface of the
second outsole portion, and wherein the sidewalls of the second
outsole portion are curved, and wherein adjacent sidewalls of the
second outsole portion curve in opposite directions.
10. The sole structure of claim 9, wherein the one or more outsole
portions incudes a third outsole portion having: a plurality of
alternating upward-facing channels and downward-facing channels;
wherein each channel of the third outsole portion has a base
element and two sidewalls, with adjacent upward-facing channels and
downward-facing channels of the third outsole portion sharing a
common sidewall, wherein the base elements of the downward-facing
channels of the third outsole portion form an upper surface of the
third outsole portion and the base elements of the upward-facing
channels of the third outsole portion form a lower surface of the
third outsole portion, and wherein the sidewalls of the third
outsole portion are curved, and wherein adjacent sidewalls of the
third outsole portion curve in opposite directions.
11. The sole structure of claim 1, wherein the first outsole
portion is located in a forefoot region of the sole structure.
12. The sole structure of claim 1, wherein widths of the base
elements of the downward-facing channels of the first outsole
portion are greater than 2.0 mm.
13. A sole structure for an article of footwear, comprising: a
first outsole portion having: a first upward-facing channel defined
by a first base element, a first sidewall, and a second sidewall,
wherein the first sidewall and the second sidewall are curved in
opposite directions, a first downward-facing channel defined by a
second base element, the second sidewall, and a third sidewall,
wherein the third sidewall is curved in an opposite direction from
the second sidewall, a second upward-facing channel defined by a
third base element, the third sidewall, and a fourth sidewall,
wherein the fourth sidewall is curved in an opposite direction from
the third sidewall, and a second downward-facing channel defined by
a fourth base element, the fourth sidewall, and a fifth sidewall,
wherein the fifth sidewall is curved in an opposite direction from
the fourth sidewall.
14. The sole structure of claim 13, wherein the first, second,
third, fourth, and fifth sidewalls are curved such that the first
and second upward-facing channels have a convex configuration and
the first and second downward-facing channels have a concave
configuration.
15. The sole structure of claim 13, wherein a thickness of the
first base element varies, and wherein a thickness of the third
base element varies.
16. The sole structure of claim 13, wherein the first outsole
portion is located in a heel region of the sole structure.
17. The sole structure of claim 13, further comprising: a second
outsole portion having: a third upward-facing channel defined by a
fifth base element, a sixth sidewall, and a seventh sidewall,
wherein the sixth sidewall and the seventh sidewall are curved in
opposite directions, a third downward-facing channel defined by a
sixth base element, the seventh sidewall, and an eighth sidewall,
wherein the eighth sidewall is curved in an opposite direction from
the seventh sidewall, a fourth upward-facing channel defined by a
seventh base element, the eighth sidewall, and a ninth sidewall,
wherein the ninth sidewall is curved in an opposite direction from
the eighth sidewall, and a fourth downward-facing channel defined
by an eighth base element, the ninth sidewall, and a tenth
sidewall, wherein the tenth sidewall is curved in an opposite
direction from the ninth sidewall.
18. The sole structure of claim 13, further comprising: a third
outsole portion having: a fifth upward-facing channel defined by a
ninth base element, an eleventh sidewall, and a twelfth sidewall,
wherein the eleventh sidewall and the twelfth sidewall are curved
in opposite directions, a fifth downward-facing channel defined by
a tenth base element, the twelfth sidewall, and a thirteenth
sidewall, wherein the thirteenth sidewall is curved in an opposite
direction from the twelfth sidewall, a sixth upward-facing channel
defined by an eleventh base element, the thirteenth sidewall, and a
fourteenth sidewall, wherein the fourteenth sidewall is curved in
an opposite direction from the thirteenth sidewall, and a sixth
downward-facing channel defined by an twelfth base element, the
fourteenth sidewall, and a fifteenth sidewall, wherein the
fifteenth sidewall is curved in an opposite direction from the
fourteenth sidewall.
19. An article of footwear, comprising: an upper; and a sole
structure engaged with the upper, the sole structure including a
first outsole portion having: a first upward-facing channel defined
by a first base element, a first sidewall, and a second sidewall,
wherein the first sidewall and the second sidewall are curved in
opposite directions, a first downward-facing channel defined by a
second base element, the second sidewall, and a third sidewall,
wherein the third sidewall is curved in an opposite direction from
the second sidewall, a second upward-facing channel defined by a
third base element, the third sidewall, and a fourth sidewall,
wherein the fourth sidewall is curved in an opposite direction from
the third sidewall, and a second downward-facing channel defined by
a fourth base element, the fourth sidewall, and a fifth sidewall,
wherein the fifth sidewall is curved in an opposite direction from
the fourth sidewall.
20. The article of footwear of claim 19, further comprising: a
second outsole portion having: a third upward-facing channel
defined by a fifth base element, a sixth sidewall, and a seventh
sidewall, wherein the sixth sidewall and the seventh sidewall are
curved in opposite directions, a third downward-facing channel
defined by a sixth base element, the seventh sidewall, and an
eighth sidewall, wherein the eighth sidewall is curved in an
opposite direction from the seventh sidewall, a fourth
upward-facing channel defined by a seventh base element, the eighth
sidewall, and a ninth sidewall, wherein the ninth sidewall is
curved in an opposite direction from the eighth sidewall, and a
fourth downward-facing channel defined by an eighth base element,
the ninth sidewall, and a tenth sidewall, wherein the tenth
sidewall is curved in an opposite direction from the ninth
sidewall.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
15/455,229 filed on Mar. 10, 2017, which is a continuation of
application Ser. No. 13/556,872 filed on Jul. 24, 2012. Application
Ser. No. 13/556,872 and application Ser. No. 15/455,229, in their
entireties, are incorporated herein by reference.
FIELD
[0002] Aspects of the present invention relate to sole structures
for articles of footwear. More particularly, various examples
relate to outsole structures having improved impact-attenuation
and/or energy-absorption.
BACKGROUND
[0003] To keep a wearer safe and comfortable, footwear is called
upon to perform a variety of functions. For example, the sole
structure of footwear should provide adequate support and impact
force attenuation properties to prevent injury and reduce fatigue,
while at the same time provide adequate flexibility so that the
sole structure articulates, flexes, stretches, or otherwise moves
to allow an individual to fully utilize the natural motion of the
foot.
[0004] High-action sports, such as the sport of skateboarding,
impose special demands upon players and their footwear. For
example, during any given run, skateboarders perform a wide variety
of movements or tricks (e.g., carving, pops, flips, ollies,
grinding, twists, jumps, etc.). During all of these movements,
pressure shifts from one part of the foot to another, while
traction between the skateboarder and the skateboard must be
maintained. Further, for the street skateboarder, traction between
the skateboarder's shoe and the ground propels the
skateboarder.
[0005] Additionally, skateboarding requires the skateboarder to
apply pressure to one or the other portions of the skateboard using
his or her feet in order to control the board. This requires that
skateboarders selectively apply pressure to the board through their
shoes at different locations on the bottom and edges of the shoes.
For example, for some skateboarding tricks, pressure is applied
along the lateral edge of the foot, approximately at the outer toe
line location. For other tricks, pressure is applied on the lateral
edge of the foot somewhat forward of the outer toe line location.
As the interaction between the skateboarder and the skateboard is
particularly important when performing such tricks, skateboarders
typically prefer shoes having relatively thin and flexible soles
that allow the skateboarder to "feel" the board.
[0006] Importantly, however, over the past several years skateboard
tricks have become "bigger," involving higher jumps and more air
time. These bigger skateboard tricks may result in uncomfortably
high, even damaging, impact loads being felt by the skateboarder.
Further, during many of the movements and particularly upon
landing, significant impact loads may be experienced by various
portions of the foot.
[0007] Accordingly, it would be desirable to provide footwear that
allows the wearer to better feel and grip the ground or other
foot-contacting surfaces, to achieve better dynamic control of the
wearer's movements, while at the same time providing
impact-attenuating features that protect the wearer from impacts
due to these dynamic movements.
BRIEF SUMMARY
[0008] According to aspects of the invention, a sole structure for
an article of footwear has one or more outsole portions. At least
one of these outsole portions has a plurality of alternating
upward-facing and downward-facing elongate channels. The channels
may have a base element and two sidewalls, with adjacent
upward-facing and downward-facing channels sharing a common
sidewall. The base elements of the downward-facing channels form an
upper surface of each outsole portion and the base elements of the
upward-facing channels form a lower surface of each outsole
portion. A first outsole portion has a pressure-versus-strain curve
having a local maximum at a "trip point" pressure value and a first
strain value and the pressure-versus-strain curve has a change in
strain of at least approximately 10% before a second occurrence of
the "trip point" pressure value is reached.
[0009] According to certain aspects, the first outsole portion may
have a local minimum pressure value between the first and second
occurrences of the "trip point" pressure value, and the local
minimum pressure value may be greater than approximately 70% of the
"trip point" pressure value.
[0010] According to other aspects, the first outsole portion may
have a pressure-carrying capacity between the first and second
occurrences of the "trip point" pressure value that varies by less
than or equal to approximately 20% over a change in strain of at
least approximately 15%.
[0011] According to further aspects, the first outsole portion may
absorb a first amount of energy per unit area at the first
occurrence of the "trip point" pressure value and absorb a second
amount of energy per unit area between the first and second
occurrences of the "trip point" pressure value. The value of the
second energy per unit area may be at least 70% of the value of the
first energy per unit area.
[0012] According to some aspects, the first outsole portion may
have a height dimension of less than or equal to 8.0 mm, measured
from the upper surface to the lower surface. The first outsole
portion may absorb an energy per unit area of at least 600
J/mm.sup.2 without exceeding a pressure of 350 kPa. Alternatively,
the first outsole portion may absorb an energy per unit area of at
least 900 J/mm.sup.2 without exceeding a pressure of 500 kPa. Also,
alternatively, the first outsole portion may absorb an energy per
unit area of at least 1100 J/mm.sup.2 without exceeding a pressure
of 700 kPa.
[0013] According to other aspects, the first outsole portion may
have a "trip point" pressure value of between approximately 250 kPa
and approximately 450 kPa, or alternatively, the first outsole
portion may have a "trip point" pressure value of between
approximately 450 kPa and approximately 650 kPa.
[0014] According to even other aspects, the upward-facing channels
of the first outsole portion may undulate in the plane of the sole.
Thus, for example, when viewed perpendicular to the plane of the
sole (e.g., when viewed from above or from below), the channels may
have a zigzag, sinusoidal, sawtoothed, or other regular or
irregular wave-like configuration. Further, when viewed
perpendicular to the plane of the sole, the base elements of the
upward-facing channels (i.e., the lower base elements) may also
have the zigzag (or other wave-like) configuration. Similarly, the
downward-facing channels of the first outsole portion may undulate
in the plane of the sole. Thus, as an example, when viewed
perpendicular to the plane of the sole, the channels may have a
zigzag, sinusoidal, sawtoothed, or other regular or irregular
wave-like configuration. Correspondingly, when viewed perpendicular
to the plane of the sole, the base elements of the downward-facing
channels (i.e., the upper base elements) may have an undulating,
wave-like configuration. The undulating configuration(s) of the
lower base elements may be the same as the undulating
configuration(s) of the upper base elements. Optionally, the
undulating configuration(s) of the lower base elements may be
different than the undulating configuration(s) of the upper base
elements.
[0015] According to some aspects, the sidewalls of the channels may
form acute, perpendicular, or obtuse angles from the upper surface.
In some example embodiments, the angles of the sidewalls to the
upper surface of the first outsole portion may be greater than or
equal to approximately 70 degrees. The widths of the bases of the
downward-facing channels of the first outsole portion may be
approximately 3.0 mm and the widths of the bases of the
upward-facing channels of the first outsole portion may be less
than approximately 1.25 mm. The thickness of the sidewalls of the
first outsole portion may be between approximately 0.8 mm and
approximately 1.5 mm. The thickness of the bases of the
upward-facing channels of the first outsole portion may be between
approximately 1.0 mm and approximately 1.5 mm.
[0016] According to another aspect of the invention, a sole
structure for an article of footwear includes one or more outsole
portions. Each outsole portion has a plurality of alternating
upward-facing and downward-facing elongate channels. Each channel
has a base and two sidewalls, with adjacent upward-facing and
downward-facing channels sharing a common sidewall. The bases of
the downward-facing channels form an upper surface of each outsole
portion and the bases of the upward-facing channels form a lower
surface of each outsole portion. The sidewalls are arranged at a
non-perpendicular angle to the upper surface of the first outsole
portion. A first outsole portion has a monotonically increasing
vertical pressure-carrying capacity as a function of strain, as
measured over a 40 mm diameter area, until a local maximum "trip
point" pressure value is reached. Beyond this first occurrence of
the "trip point" pressure value the first outsole portion has a
local minimum pressure value that is between 60% to 100% of the
"trip point" pressure value.
[0017] An article of footwear including an upper attached to the
sole structure disclosed herein is also provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The foregoing Summary, as well as the following Detailed
Description, will be better understood when read in conjunction
with the accompanying drawings.
[0019] FIG. 1A is a perspective view, looking from the lateral
side, of an article of footwear having an upper and a sole
structure in accordance with aspects of this disclosure.
[0020] FIG. 1B is a bottom view of the article of footwear of FIG.
1A.
[0021] FIG. 1C is a schematic perspective view, looking from the
lateral side, of an article of footwear, having a cut-away view in
the forefoot region, in accordance with aspects of this
disclosure.
[0022] FIG. 2A is schematic of a representative "pressure versus
displacement" curve of the type that may characterize outsole
portions in accordance with aspects of this disclosure.
[0023] FIG. 2B is a set of experimentally measured "pressure versus
strain" curves of certain exemplary embodiments of outsole portions
in accordance with aspects of this disclosure.
[0024] FIG. 3A is a perspective, cut-away, view of an embodiment of
an outsole portion in an unloaded configuration in accordance with
aspects of this disclosure.
[0025] FIG. 3B is a perspective, cut-away, view of an embodiment of
an outsole portion in a buckled configuration in accordance with
aspects of this disclosure.
[0026] FIG. 4 is a schematic cross-section, viewed down the
elongate axis of a channel, of a section of a representative
outsole portion in accordance with aspects of this disclosure.
[0027] FIGS. 5A through 5G are schematic cross sections, viewed
down the elongate axis of a channel, of a section of representative
outsole portions illustrating certain aspects of the outsole
portions in accordance with aspects of this disclosure.
[0028] FIGS. 6A and 6B are schematic cross sections, viewed down
the elongate axis of a channel, of sections of representative
outsole portions illustrating certain aspects of the outsole
portions in accordance with aspects of this disclosure.
[0029] FIGS. 7A through 7C are simplified schematic bottom plan
views of various alternative outsole portions in accordance with
aspects of this disclosure.
[0030] FIGS. 8A through 8C are perspective, cut-away, views of
various alternative base element and channel configurations for
representative outsole portions in accordance with aspects of this
disclosure.
[0031] FIGS. 9A through 9C are perspective, cut-away,views of
various alternative base element and channel configurations for
representative outsole portions in accordance with aspects of this
disclosure.
[0032] FIG. 10 is a bottom plan view of an outsole structure in
accordance with certain aspects of this disclosure.
[0033] FIG. 11 is a bottom plan view of an outsole structure in
accordance with certain aspects of this disclosure.
[0034] FIG. 12 is a bottom plan view of an outsole structure in
accordance with certain aspects of this disclosure.
[0035] FIG. 13 is a graph of energy/area versus pressure for a set
of exemplary embodiments of outsole portions in accordance with
certain aspects of this disclosure.
[0036] FIGS. 14A and 14B are simplified schematic bottom plan views
of various alternative outsole portions in accordance with aspects
of this disclosure.
[0037] FIGS. 15A and 15B are schematic cross sections, viewed
crosswise to the elongate axis of a channel and taken through a
lower base element, of an alternative base element configuration
illustrating an outsole portion in accordance with aspects of this
disclosure.
[0038] It should be understood that the appended drawings are not
necessarily to scale, presenting a somewhat simplified
representation of various features illustrative of specific aspects
of the invention. Certain features of the illustrated embodiments
may have been enlarged or distorted relative to others to
facilitate visualization and clear understanding. In particular,
thin features may be thickened, for example, for clarity of
illustration.
DETAILED DESCRIPTION
[0039] The following discussion and accompanying figures disclose
articles of footwear having sole structures with sole geometries in
accordance with various embodiments of the present disclosure.
Concepts related to the sole geometry are disclosed with reference
to a sole structure for an article of athletic footwear having a
configuration suitable for the activity of skateboarding. However,
the disclosed sole structure is not solely limited to footwear
designed for skateboarding, and may be incorporated into a wide
range of athletic footwear styles, including shoes that are
suitable for rock climbing, bouldering, hiking, running, baseball,
basketball, cross-training, football, rugby, tennis, volleyball,
and walking, for example. In addition, a sole structure according
to various embodiments as disclosed herein may be incorporated into
footwear that is generally considered to be non-athletic, including
a variety of dress shoes, casual shoes, sandals, slippers, and
boots. An individual skilled in the relevant art will appreciate,
given the benefit of this specification, that the concepts
disclosed herein with regard to the sole structure apply to a wide
variety of footwear styles, in addition to the specific styles
discussed in the following material and depicted in the
accompanying figures.
[0040] Sports generally involve consistent pounding of the foot
and/or periodic high impact loads on the foot. For example,
skateboarding is a sport that is known to involve high impact
loading under the foot, especially when unsuccessfully or awkwardly
landing tricks and/or inadvertently coming off the board on hard,
unforgiving surfaces. Over the past several years, skateboarding
tricks have gotten much bigger, resulting in even higher impact
loads, especially in the medial and the heel regions of the foot.
This is true whether the foot remains on the board during landing
or, alternatively, if the landing is off the board. It is not
unheard of for skateboarders to experience heel bruising and even
micro-fractures.
[0041] A sole structure for an article of footwear having an
impact-attenuation system capable of handling the high "big trick"
impact loads, without sacrificing the intimate feel for the board
desired by skateboarders, is sought. Thus, it may be advantageous
to have a sole structure that responds somewhat stiffly when a user
is walking or performing relatively low impact ambulatory
activities, thereby maintaining a feel for the ground surface (or
board), and that also responds more compliantly when the user is
performing higher impact maneuvers, thereby lessening any
excessively high impact pressures that would otherwise be
experienced by the user.
[0042] In addition, the ability to "grip" the board is another
important feature desired by skateboarders. Softer materials tend
to provide higher coefficients of friction and, thus, generally
provide better traction and "grip" than harder materials. However,
softer materials also tend to wear out more quickly. Thus, another
feature sought by skateboarders is a durable sole. Indeed,
skateboarders and many other athletes desire sole structures that
provide high traction and lasting durability
[0043] Even further, skateboarders and many other athletes desire
sole structures that are light weight and low profile.
[0044] Various aspects of this disclosure relate to articles of
footwear having a sole structure with an outsole structure capable
of absorbing impact energies and mitigating impact loads.
[0045] As used herein, the modifiers "upper," "lower," "top,"
"bottom," "upward," "downward," "vertical," "horizontal,"
"longitudinal," "transverse," "front," "back" etc., unless
otherwise defined or made clear from the disclosure, are relative
terms meant to place the various structures or orientations of the
structures of the article of footwear in the context of an article
of footwear worn by a user standing on a flat, horizontal
surface.
[0046] Referring to FIGS. 1A and 1B, an article of footwear 10
generally includes two primary components: an upper 100 and a sole
structure 200. The upper 100 is secured to the sole structure 200
and forms a void on the interior of the footwear 10 for comfortably
and securely receiving a foot. The sole structure 200 is secured to
a lower portion of the upper 100 and is positioned between the foot
and the ground. Upper 100 may include an ankle opening that
provides the foot with access to the void within upper 100. As is
conventional, upper 100 may also include a vamp area having a
throat and a closure mechanism, such as laces.
[0047] Referring to FIG. 1B, typically, the sole structure 200 of
the article of footwear 10 has a forefoot region 11, a midfoot
region 12 and a heel region 13. Forefoot region 11 may further be
considered to encompass a ball region 11a and a toe region 11b.
Ball region 11a generally extends under the ball of the foot. Toe
region 11b generally extends under the toes of the foot. Although
regions 11-13 apply generally to sole structure 200, references to
regions 11-13 may also apply to article of footwear 10, upper 100,
or an individual component within either sole structure 200 or
upper 100.
[0048] The sole structure 200 of the article of footwear 10 further
has a toe or front edge 14 and a heel or back edge 15. A lateral
edge 17 and a medial edge 18 each extend from the front edge 14 to
the back edge 15. Further, the sole structure 200 of the article of
footwear 10 defines a longitudinal centerline 16 extending from the
back edge 15 to the front edge 14 and located generally midway
between the lateral edge 17 and the medial edge 18. Longitudinal
centerline 16 generally bisects sole structure 200, thereby
defining a lateral side and a medial side.
[0049] Referring to FIG. 1C, according to some embodiments, a sole
structure 200 may incorporate multiple layers, for example, an
outsole structure 210 and an insole 212. The outsole structure 210
forms the ground-engaging portion (or other contact
surface-engaging portion) of the sole structure 200, thereby
providing traction and a feel for the engaged surface. The outsole
structure 210 may also provide stability and localized support for
the foot. Even further, the outsole structure 210 may provide
impact-attenuation capabilities. Aspects of certain outsole
structures will be discussed in detail below.
[0050] The insole 212 (or sockliner), is generally a thin,
compressible member located within the void for receiving the foot
and proximate to a lower surface of the foot. The insole 212, which
is configured to enhance footwear comfort, may be formed of foam.
For example, the insole 212 may be formed of a 5.0 mm thick layer
of polyurethane foam, e.g., injected Phylon. Other materials such
as ethylene vinyl acetate or other foamed rubber may be used to
form an insole. Typically, the insole or sockliner 212 is not glued
or otherwise attached to the other components of the sole structure
200, although it may be attached, if desired.
[0051] In addition to outsole structures 210 and insoles 212,
certain sole structures may also include midsoles 214.
Conventionally, midsoles 214 form a middle layer of the sole
structure 200 and are positioned between the outsole structure 210
and the insole 212. The midsole 214 may be secured to the upper 100
along the lower length of the upper. Midsoles 214 may have
impact-attenuation capabilities, thereby mitigating ground (or
other contact surface) reaction forces and lessening stresses upon
the foot and leg. Further, midsoles 214 may provide stability
and/or additional localized support or motion control for the foot
or portions of the foot.
[0052] According to certain aspects, a midsole 214 need not be
provided. This may be particularly appropriate when the sole
structure 200 is designed to have a low profile and/or to be
lightweight.
[0053] The outsole structure 210 may have one or more regions or
portions 220 defined. For example, as shown in FIG. 1B, the outsole
structure 210 may include a forefoot portion 220a, a midfoot
portion 220b and a heel portion 220c. Further, the outsole
structure 210 may have a medial-side forefoot portion 220d and a
lateral-side forefoot portion 220e. Additionally, the midfoot
region may have a medial-side midfoot portion 220f and a
lateral-side midfoot portion 220g. Heel portions may be similarly
defined, as may toe portions. Further, portions associated with
other regions of the foot, such as the ball of the foot, the arch,
the great toe, etc., as would be known to persons of skill in the
art, may also be used to define portions of the outsole structure
210.
[0054] According to some aspects of the present disclosure and
referring to FIGS. 2A and 2B, at least some of the various outsole
portions 220 have a pressure load versus displacement response
system with multiple regimes, wherein each regime is associated
with a displacement range and a stiffness characteristic. The
stiffness characteristic of the outsole portion 220 may be
described by the slope of a curve that relates the pressure
response to the displacement. According to certain aspects, at
lower loads, for example when walking or when a skateboard remains
grounded, the outsole portion 220 reacts to pressure loads
according to a first stiffness characteristic; and at higher loads,
for example impact loads experienced when running or when landing
after performing a big trick on the skateboard, the outsole
structure 210 reacts to the pressure loads according to a second
stiffness characteristic. Specifically, in some embodiments, the
outsole portion 220 reacts to lower impact loads in a first,
non-buckled, configuration and reacts to higher impact loads in a
second, post-buckled, configuration. The first, non-buckled
configuration may have an essentially linearly increasing
load-versus-displacement curve. In the second, post-buckled
configuration, the load-versus-displacement curve may have a
negative slope and/or a substantially flat slope before the
pressure load once again increases as a function of displacement.
For purposes of this disclosure, "pressure" or a "pressure load" is
measured as the applied load divided by the areal footprint of the
loading fixture. Thus, a 100 Newton load applied with a 40 mm round
tup results in an applied pressure load of 79.6 kPa (i.e., 100
N/(.pi.(20 mm).sup.2)). In other words, the pressure is determined
using the overall gross area of the sole portion to which the load
is applied, not just the specific net area of those elements of the
sole portion that are directly contacted by the loading
fixture.
[0055] Thus, according to aspects of the present disclosure, an
outsole portion 220 may be designed with a particular structural
configuration such that buckling occurs when the outsole structure
is subjected to a predetermined pressure loading. For purposes of
this disclosure, "buckling" refers to the occurrence of a
relatively large deflection of a structure subjected to a
compression load upon a relatively small increase in the
compression load. The relatively large deflection in the direction
of the application of the load may occur in conjunction with a
large lateral deflection (i.e., a deflection lateral to the
direction of the application of the load) of one or more components
of the structure. For example, when a structure that consists of
one or more relatively long, thin, slender members (e.g., plates or
columns) is subjected to an initial compressive load, the long
slender members may initially compress along their length in
accordance with an essentially linear elastic stress-strain curve
of the material. When this structure is then subjected to an
increasing compressive load, at a certain critical load (referred
to herein as a "trip point") the long slender members may deflect
laterally (bowing out) such that the structure experiences a large
displacement in the direction of load application with a small
increase in applied load. This large lateral deflection changes the
load-carrying configuration of the structure, in essence, changing
the stiffness of the structure. In the buckled configuration, the
load required to compress the structure is less than the load
required to compress the structure the same amount in the initial
configuration. Thus, for a given increase in load, relatively large
compressive displacements occur in the buckled structure. In other
words, in the buckled configuration, the structure is "softened"
and impact loads may be attenuated. If the structure continues to
compress under the load, at some point it will "bottom out," and
once again, the compression will be governed by the stiffer
stress/strain curve of the material.
[0056] A schematic example of a load versus displacement curve, as
may be used to generally characterize such a multi-regime load
versus displacement response system, is shown in FIG. 2A. This
particular curve graphs "pressure" versus "displacement" for a
generic outsole portion 220 in accordance with the present
disclosure. In a first regime (I), an "initial stiffness" regime,
the pressure versus displacement curve is characterized by a
monotonically increasing response, i.e., as the displacement
increases, the pressure required to effect that displacement
increases. This initial stiffness regime is typically governed by
the properties of the material(s) forming the outsole portion 220.
At a "trip point" pressure, the system transitions to a second,
"buckling" regime (II). In this buckling regime, it takes less
force (or pressure) to compress the outsole structure 210 such that
a cushioning effect is experienced. In other words, in the second
regime (II), the pressure loading does not exceed the "trip point"
pressure. This second regime is typically governed, not only by the
material characteristics of the outsole portion 220, but also by
the structural configuration of the outsole. Finally, in a third
regime (III), a "bottomed out" regime, the pressure versus
displacement curve may once again be characterized as being
typically governed by the properties of the material(s) forming the
outsole portion 220, rather than being governed by the particular
structural configuration of the outsole portion 220.
[0057] Within the second regime (II) the
pressure-versus-displacement curve of the outsole portions 220 may
be described as being generally "S-shaped." This S-shape is due to
the presence of the "trip point," which is a local maximum, a
"point-of-inflection," and a local minimum. For purposes of the
present disclosure, the term "point-of-inflection" refers to a
point on a curve at which the change in curvature changes sign,
i.e., when the curve changes from being concave downward to concave
upward, or vice versa. In other words, the "point-of-inflection" is
the point on a curve at which the second derivative changes sign.
Even more simply, the point of inflection is where the tangent to
the curve crosses the curve. At the local minimum, the pressure is
at its minimum in the buckled regime. Further, relative to the
first and third regimes, the change in the pressure carrying
capacity of the outsole portions 220 in the second regime remains
relatively flat.
[0058] According to certain aspects, the buckling of the outsole
portion 220 is elastic buckling. For purposes of the present
disclosure, the phrase "elastically-buckled" (and variations
thereof) refers to a configuration of a load-carrying element
wherein an abrupt and large increase in the displacement (usually
accompanied by a relatively large lateral deflection) of the
load-carrying element(s) occurs with only a minimal increase in the
applied load, while the stresses acting on the load-carrying
element remain wholly elastic. In such case, when the load is
removed, the load-carrying element or elements assume their
original configuration (i.e., the zero-load configuration) without
experiencing any permanent deformation or set. In other words,
elastic buckling has occurred if the buckled structure regains its
original configuration upon the release of the buckling load. FIG.
2B illustrates mechanical test results as pressure-versus-strain
curves for certain exemplary embodiments of the outsole portions
220. A 40 mm round tup was used to compress the sample outsole
portions 220 (using a 3 Hz haversine waveform and a compression of
4 mm). Thus, for purposes of the present disclosure, the vertical
pressure-carrying capacity of the outsole portions 220 is measured
over a circular area having a 40 mm diameter. The geometry for the
tested samples is presented in Table I, below. The tested outsole
portion samples listed in Table I were made of a solid rubber
having a typical Shore A hardness of between 74-80. In general, the
outsole portions are not limited to being made of a solid rubber
having a Shore A hardness of 74-80, but may be made of any suitable
material, including conventional outsole rubbers as known and used
by persons of ordinary skill in the art.
[0059] In FIG. 2B, several pressure-versus-strain curves for
various outsole portions are presented. The pressure-versus-strain
curves have a local maximum pressure at a "trip point" pressure
value and a first strain value. Further, the pressure-versus-strain
curves have a local minimum pressure value at a second strain
value. The second strain value is greater than the first strain
value. Even further, these pressure-versus-strain curves have a
second occurrence of the "trip point" pressure value at a third
strain value, which is greater than the second strain value. The
change in the strain between the first occurrence of the "trip
point" pressure value and the second occurrence of the "trip point"
pressure value may be at least 10%, and more typically may be
greater than 20%. The pressure-carrying capacity of the outsole
portion between the first and second occurrences of the "trip
point" pressure value may vary by less than or equal to
approximately 20%. For example, in FIG. 2B, the outsole portion 220
associated with curve 6 (sample 6 of Table I) has a "trip point"
pressure value (see point "a") of approximately 300 kPa at a strain
of approximately 16%. At a strain of approximately 46%, the
pressure-carrying capacity of the outsole portion associated with
curve 6 again reaches the "trip point" pressure value of
approximately 300 kPa. This second occurrence of the "trip point"
pressure value occurs at point "c". Between the strains of 16% and
46%, a local minimum pressure carrying capacity of the outsole
portion associated with curve 6 is approximately 250 kPa at a
strain of approximately 36% (see point "b"). Thus, the outsole
portion 220 associated with curve 6 has a "trip point" pressure
value of approximately 300 kPa, a second regime that extends over a
strain range of approximately 30% (i.e., the change in the strain
between the first occurrence of the "trip point" pressure value and
the second occurrence of the "trip point" pressure value is 46%
minus 16%), and a change in pressure-carrying capacity over the
extent of the second regime of approximately 50 kPa (i.e., 300 kPa
minus 250 kPa). In other words, the pressure-carrying capacity of
the outsole portion 220 associated with curve 6 changed by only
approximately 17% (i.e., 50 kPa divided by 300 kPa) over a strain
range of approximately 30%.
[0060] In FIG. 2B, the outsole portion 220 associated with curve 7
(sample 7 of Table I) has a "trip point" pressure value of
approximately 350 kPa at a strain of approximately 17%. At a strain
of approximately 48%, the pressure-carrying capacity of the outsole
portion associated with curve 7 again reaches the "trip point"
value of approximately 350 kPa. Between the strains of 17% and 48%,
the minimum pressure carrying capacity of the outsole portion
associated with curve 7 is approximately 280 kPa at a strain of
approximately 35%. Thus, the outsole portion 220 associated with
curve 7 has a "trip point" pressure value of approximately 350 kPa,
a second regime that extends over a strain range of approximately
31% (i.e., 48% minus 17%), and a change in pressure-carrying
capacity over the extent of the second regime of approximately 70
kPa (i.e., 350 kPa minus 280 kPa). In other words, the
pressure-carrying capacity of the outsole portion 220 associated
with curve 7 changed by only approximately 20% (i.e., 70 kPa
divided by 350 kPa) over a strain range of approximately 31%.
[0061] Looking at another curve in FIG. 2B in detail, it is seen
that the outsole portion 220 associated with curve 1 (sample 1 of
Table I) has a "trip point" pressure value of approximately 500 kPa
at a strain of approximately 23%. At a strain of approximately 47%,
the pressure-carrying capacity of the outsole portion associated
with curve 1 again reaches the "trip point" value of approximately
500 kPa. Between the strains of 23% and 47%, the minimum pressure
carrying capacity of the outsole portion associated with curve 1 is
approximately 420 kPa at a strain of approximately 41%. Thus, the
outsole portion 220 associated with curve 1 has a "trip point"
pressure value of approximately 500 kPa, a second regime that
extends over a strain range of approximately 24% (i.e., 47% minus
23%), and a change in pressure-carrying capacity over the extent of
the second regime of approximately 80 kPa (i.e., 500 kPa minus 420
kPa). In other words, the pressure-carrying capacity of the outsole
portion 220 associated with curve 1 changed by only approximately
16% (i.e., 80 kPa divided by 500 kPa) over a strain range of
approximately 24%.
[0062] In FIG. 2B, the outsole portion 220 associated with curve 11
(sample 11 of Table I) has a "trip point" pressure value of
approximately 590 kPa at a strain of approximately 27%. At a strain
of approximately 42%, the pressure-carrying capacity of the outsole
portion associated with curve 11 again reaches the "trip point"
value of approximately 590 kPa. Between the strains of 27% and 42%,
the minimum pressure carrying capacity of the outsole portion
associated with curve 11 is approximately 560 kPa at a strain of
approximately 37%. Thus, the outsole portion 220 associated with
curve 11 has a "trip point" pressure value of approximately 590
kPa, a second regime that extends over a strain range of
approximately 15% (i.e., 42% minus 27%), and a change in
pressure-carrying capacity over the extent of the second regime of
approximately 30 kPa (i.e., 590 kPa minus 560 kPa). In other words,
the pressure-carrying capacity of the outsole portion 220
associated with curve 11 changed by only approximately 5% (i.e., 30
kPa divided by 590 kPa) over a strain range of approximately
15%.
[0063] In general, the curves of FIG. 2B illustrate that the
outsole portions 220 have pressure-versus-strain curves exhibiting
a local maximum pressure (i.e., the "trip point" pressure value) at
a first strain value and a change in strain of at least
approximately 10% before the "trip point" pressure value is reached
again. For certain embodiments, it can be seen that the change in
strain between the first and second occurrences of the "trip point"
pressure value may be at least approximately 15%, 20%, 25%, 30% or
even greater than approximately 30%. Further, it can be seen that
the curves of FIG. 2B illustrate that the outsole portions 220 have
pressure-versus-strain curves exhibiting a local minimum pressure
between the first and second occurrences of the "trip point"
pressure value. This local minimum pressure may be between
approximately 60% to 100% of the "trip point" value. For certain
embodiments, the local minimum pressure may be greater than
approximately 70%, greater than approximately 80% or even greater
than approximately 90% of the "trip point" pressure value. In other
words, it can be seen that the change in pressure between the first
and second occurrences of the "trip point" pressure value may be
less than approximately 40%, 30%, 25%, 20%, 15%, 10% or even less
than or equal to approximately 5%. Additionally, between the first
and second occurrences of the "trip point" pressure value the
change in strain may be greater than or equal to approximately 10%,
15%, 20%, 25% or 30%.
[0064] According to aspects of the disclosure and referring now to
FIGS. 3A, 3B and 4, at least one or more regions or outsole
portions 220 of the outsole structure 210 has a zig-zagged channel
configuration. The channels 230, 240 extend between an upper or top
layer 222 and a lower or bottom layer 224, wherein the bottom layer
224 is vertically displaced from the top layer 222. The top layer
222 is provided to support the foot and is located in the interior
of the footwear. The top layer 222, as a whole, may be considered
to be essentially planar, with only slight curvatures or
out-of-plane geometries as would be in keeping with an outsole
structure 210 following the contours of a foot. The bottom layer
224 is provided to contact the ground (the term "ground" as used
herein encompasses any type of contact surface). According to
certain embodiments the bottom layer 224 of the outsole structure
210 as a whole may be considered to be essentially planar, with
only slight curvatures or out-of-plane geometries. In certain other
embodiments, select portions of the bottom layer of the outsole
structure 210 (for example, the bottom layer 224 in the midfoot
portion 220b) may depart from the plane of the remainder of the
bottom layer.
[0065] Thus, the outsole structure 210 may include one or more
outsole portions 220 and one or more of these outsole portions 220
may have a multi-regime pressure load versus displacement response
system as discussed above.
[0066] Referring again to FIGS. 3A, 3B and 4 and according to
certain aspects of the disclosure, a multi-regime outsole portion
220 includes a plurality of alternating upward-facing elongate
channels 230 and downward-facing elongate channels 240. FIG. 3A is
a perspective, cut-away, view of an embodiment of an outsole
portion 220 in its undeformed, unloaded configuration; FIG. 3B is a
perspective, cut-away, view of an embodiment of an outsole portion
220 in a buckled configuration. FIG. 4 is a cross-section, viewed
down the elongate axis of channels 230 and 240, of a section of an
outsole portion 220. As best shown in FIG. 4, each channel 230, 240
has a base element 232, 242 and two sidewalls 234, 244, with
adjacent upward-facing and downward-facing channels 230, 240
sharing common sidewalls. The base elements 232, 242 and the
sidewalls 234, 244 extend along the elongated lengths of the
channels 230, 240. The plurality of base elements 242 of the
downward-facing channels 240, in the aggregate, forms the top layer
222 of the outsole portion 220. In other words, the top layer 222
is not continuous, but is formed of discrete base elements 242 that
in the aggregate form a platform for a foot to (directly or
indirectly) stand on. Because the base element 242 of each
downward-facing channel 240 is generally independent of and
discrete from the base elements 242 of the adjacent downward-facing
channels 240, the top layer 222 is formed as a series or an array
of, at least substantially, discrete base elements 242. Similarly,
the plurality of base elements 232 of the upward-facing channels
230, in the aggregate, forms the bottom layer 224 of the outsole
portion 220. Because, in general, the base element 232 of each
upward-facing channel 230 is independent of and discrete from the
base elements 232 of the adjacent upward-facing channels 230, the
bottom layer 224 is formed as a series or an array of, at least
substantially, discrete base elements 232. These base elements 232
may move relative to one another in a quasi-independent manner. In
some constructions, the independent and discrete base elements 232,
242 may be connected together over some portions of their
structure, e.g., along the perimeter edges of the outsole structure
210, through an interconnecting ridge or rib structure, etc.
[0067] The elongate sidewall elements 234, 244 are plate-like
elements that extend from the elongate base elements 242 of the top
layer 222 to the elongate base elements 232 of the bottom layer
224, thereby forming the alternating upward-facing and
downward-facing channels 230, 240. Specifically, each of the
sidewall elements 234, 244 extends from an elongated edge of one of
the base elements 242 of the top layer 222 to an elongated edge of
one of the base elements 232 of the bottom layer 224. At least one
of the sidewalls 234, 244 of each channel 230, 240 is arranged at
an angle to the top layer 222 of the outsole portion 220 that is
greater than 45 degrees. More typically the sidewalls 234, 244 may
extend at an angle of 70 degrees or greater from the surface plane
of the top layer 222.
[0068] Thus, according to aspects of the disclosure, the outsole
portion 220 has a top layer 222 a bottom layer 224, and a plurality
of sidewalls 234, 244 extending therebetween, wherein the top layer
222, the bottom layer 224 and the sidewalls 234, 244 are configured
to provide an array of alternating upward-facing channels 230
(upper channels) and downward-facing channels 240 (lower channels).
In the embodiment of FIG. 4, as viewed down the elongated length of
the channels 230, 240 (i.e., in a vertical plane perpendicular to
the sidewalls 234, 244 of the channels), each of the upper and
lower channels 230, 240 is a C-channel having outwardly angled
sidewalls 234, 244, i.e., sidewalls that form an angle (A) with the
upper base elements 242. When the angled sidewalls 234, 244 diverge
from one another as shown in FIG. 4 (i.e., the angle (A) is an
acute angle), this "splayed" C-channel may also be referred to as a
"hat section." Further, in this example embodiment, the thickness
(TU) of the upper base elements 242 (and, thereby, also of the top
or upper layer 222 of the outsole portion 220), the thickness (TL)
of the lower base elements 232 (and, thereby, also of the bottom or
lower layer 224 of the outsole portion 220), and the thickness (TS)
of the sidewalls 234, 244 are constant. Even further, in this
particular example embodiment, the width (WU) of the upper,
elongated, base element 242 is the same as the width (WL) of the
lower, elongated, base element 232. Additionally, in this
particular example embodiment, the height (H) of the outsole
portion 220 does not vary and the heights (HU, HL) of the upper and
lower channels 230, 240 are equal to one another and remain
constant for the entire array of channels. Finally, in the
embodiment of FIG. 4, the upper channel 230, if rotated 180 degrees
around a horizontal axis, is identical to the lower channel
240.
[0069] The particular dimensions of the outsole portion 220 and of
the channels 230, 240 may depend upon the particular application
for the article of footwear 10. Further, the dimensions of the
outsole portion 220 and of the channels 230, 240 may depend upon
the degree of impact-attenuation desired, the degree of flexibility
desired, the locations of the channels 230, 240 under the foot, the
existence and/or spacing of adjacent channels 230, 240, the
material used to form the channels 230, 240, the user's "feel"
preferences, etc.
[0070] For example, still referring to FIG. 4, the height (H) of
the outsole portion 220 may vary depending upon its location in the
outsole structure 210. Thus, the height (H) of the outsole portion
220 in the heel portion 220c may be greater than the height (H) in
the forefoot portion 220a. In general the height (H) of the outsole
portion 220 may range from approximately 4.0 mm to approximately
18.0 mm. For certain embodiments, the height (H) of an outsole
portion may be less than or equal to approximately 10.0 mm. For
example, the height (H) of the outsole portion may range from
approximately 4.0 mm to approximately 10.0 mm (e.g., as may be most
appropriate in a forefoot portion 220a). By way of other
non-limiting examples, the height (H) of an outsole portion 220 may
range from approximately 5.0 mm to approximately 9.0 mm or even
from approximately 6.0 mm to approximately 8.0 mm. Optionally, for
other embodiments, the height (H) of an outsole portion 220 may be
greater than or equal to approximately 10.0 mm. For example, the
height (H) of the outsole portion may range from approximately 10.0
mm to approximately 18.0 mm (as may be most appropriate in a heel
portion 220c or, for example, for a basketball shoe). Thus, for
example, the height (H) of an outsole portion 220 may range from
approximately 10.0 mm to approximately 16.0 mm or even from
approximately 11.0 mm to approximately 14.0 mm. For even other
alternative embodiments, the height (H) of an outsole portion 220
may range from approximately 6.0 mm to approximately 17.0 mm, from
approximately 6.0 mm to approximately 12.0 mm, from approximately
9.0 mm to approximately 16.0 mm, or even from approximately 10.0 mm
to approximately 15.0 mm depending upon the expected loading
conditions and the desired stiffness characteristics. The height
(H) of any one channel 230, 240 may vary along the length of the
channel 230, 240. Further, undulations in the height (H) of the
channels 230, 240 along the lengths of the channels 230, 240 (e.g.,
vertical undulations) may assist the shoe designer in tailoring the
traction area for specific applications.
[0071] According to other aspects, the thickness (TU, TL) of the
base elements 232, 242 and the thickness (TS) of the sidewalls 234,
244 of the channels 230, 240 may depend upon the desired
performance of the outsole portion 220. Thus, in certain
embodiments, for example as shown in FIG. 4, the thicknesses of the
base elements 232, 242 and/or of the sidewalls 234, 244 may be the
same, and further, these thicknesses may be constant along the
elongated length of the channels 230, 240 and/or along the heights
(HU, HL) of the channels 230, 240. For example, the thickness (TU,
TL) of the base elements 232, 242 may range from approximately 0.5
mm to approximately 3.5 mm. In order to minimize the weight of the
outsole portions 220, the thicknesses (TU, TL) of the base elements
242, 232 may range from approximately 0.5 mm to approximately 1.5
mm or even from approximately 0.8 mm to approximately 1.3 mm. In
order to increase the durability of the outsole portions 220, the
thicknesses (TU, TL) of the base elements 242, 232 may range from
approximately 1.0 mm to approximately 3.5 mm or even from
approximately 1.2 mm to approximately 2.5 mm. In some embodiments,
the thickness (TU, TL) of the base elements 242, 232 may depend
upon their location in the outsole structure 210. Thus, the
thickness (TU, TL) of the base elements 242, 232 in the heel
portion 220c may be greater than the thickness (TU, TL) of the base
elements 242, 232 in the forefoot portion 220a. In certain other
embodiments, the thickness (TU, TL) of the base elements 242, 232
in certain medial portions (e.g., 220d, 220f, etc.) may be greater
than the thickness (TU, TL) of the base elements 242, 232 in
certain lateral portions (e.g., 220e, 220g, etc.).
[0072] Additionally, referring for example to FIG. 5A, the
thicknesses (TU) of the upper base elements 242 need not be the
same as the thicknesses (TL) of the lower base elements 232. For
example, the thickness TU may be less than the thickness TL.
Referring to FIG. 5B, in certain embodiments, the thicknesses TU',
TU'' of adjacent upper base elements 242', 242'' need not be the
same. For example, the thickness TU' may be less than the thickness
TU''. Similarly, the thicknesses TL', TL'' of adjacent lower base
elements 232', 232'' need not be the same.
[0073] According to other aspects, the thickness (TU, TL) of any
individual base element 242, 232 need not be constant. For example
as shown in FIG. 5C, the thickness TL''' of base element 232''''
may vary as the base element 232''' extends from one sidewall 234
to the other sidewall 244 (i.e., across the width (WL) of the base
element 232'''). In this illustrated example, the thickness TL'''
of the base element 232''' increases and then decreases along its
width WL. Optionally, the thickness (TU, TL) of the base elements
242, 232 may vary along the elongate axis (i.e., along the length)
of the channel 230, 240.
[0074] According to even other aspects, and referring back to FIG.
4, the thickness (TS) of the sidewalls 234, 244 may range from
approximately 0.5 mm to approximately 2.0 mm. In order to minimize
the weight of the outsole portions 220, especially where impact
loads are expected to be relatively low, the thickness (TS) of the
sidewalls 234, 244 may range from approximately 0.5 mm to
approximately 1.5 mm or even from approximately 0.8 mm to
approximately 1.3 mm. Where impact loads are expected to be
relatively high, the thickness (TS) of the sidewalls 234, 244 may
range from approximately 1.0 mm to approximately 2.0 mm or even
from approximately 1.2 mm to approximately 1.8 mm. In some
embodiments, the thickness (TS) of the sidewalls 234, 244 may
depend upon their location in the outsole structure 210. Thus, the
thickness (TS) of the sidewalls 234, 244 in the heel portion 220c
may be greater than the thickness (TS) of the sidewalls 234, 244 in
the forefoot portion 220a. In certain other embodiments, the
thicknesses (TS) of the sidewalls 234, 244 in certain medial
portions (e.g., 220d, 220f, etc.) may be greater than the
thicknesses (TS) of the sidewalls 234, 244 in certain lateral
portions (e.g., 220e, 220g, etc.) in the outsole structure 210.
[0075] In even other embodiments, referring to FIG. 5B, the
thicknesses ((TS', TS'') of adjacent sidewalls 234, 244 need not be
the same. In this illustrated example, the thickness TS' of a
sidewall 234' is greater than the thickness TS'' of an adjacent
sidewall 244'. Optionally, as best shown in FIG. 5C, the sidewalls
234, 244 need not be flat or planar, but may curve or bulge. For
example, adjacent sidewalls 234, 244 may curve in opposite
directions as shown in FIG. 5C, or they may curve in the same
direction. Further, the thickness (TS) of any individual sidewall
234, 244 need not be constant. For example, referring to FIG. 5D,
the thicknesses TS''' of sidewalls 234''' and 244''' increase as
the sidewalls 234''' and 244''' extend from the top layer 222 to
the bottom layer 224. As another optional embodiment, the
thicknesses (TS) of the sidewalls 234, 244 may vary along the
elongate axes of the channels 230, 240.
[0076] According to even additional aspects and referring back to
FIG. 4, the width (WU, WL) of the base elements 242, 232 of the
upper and lower channels 230, 240 may be selected to provide
particular performance characteristics of the outsole portion 220,
such as weight, stiffness, mounting area and traction area. Thus,
in this particular illustrated embodiment, the width (WU) of the
upper base elements 242 may be the same as the width (WL) of the
lower base elements 232. The width (WU, WL) of the base elements
242, 232 may range from approximately 1.0 mm to approximately 5.0
mm. In order to minimize the weight of the outsole portion 220, the
widths (WU) of the upper base elements 242 may range from
approximately 2.0 mm to approximately 5.0 mm or, more limited, from
approximately 2.5 mm to approximately 3.5 mm. Similarly, the widths
(WL) of the lower base elements 232 may also range from
approximately 2.0 mm to approximately 5.0 mm, or more limited, from
approximately 2.5 mm to approximately 3.5 mm. Having a relatively
wide width (WU, WL) for the base elements 242, 232 spaces the
sidewalls 234, 244 of the channels 230, 240 further apart, such
that the mass of the outsole portion 220 may be minimized. On the
other hand, in order to increase the stiffness of the outsole
structure 210, the base elements 242, 232 may be provided with
relatively narrow widths (WU, WL), such that the sidewalls 234, 244
are more closely spaced. Thus, for certain embodiments, the widths
(WU, WL) of the upper and/or lower base elements 242, 232 may range
from approximately 1.0 mm to approximately 2.0 mm or, even more
limited, from approximately 1.0 mm to approximately 1.5 mm.
[0077] In some embodiments, the width (WU, WL) of the base elements
242, 232 may depend upon their location in the outsole portion 220.
Thus, the width (WU, WL) of the base elements 242, 232 in the heel
portion 220c may be less than the width (WU, WL) of the base
elements 242, 232 in the forefoot portion 220a. In certain other
embodiments, the width (WU, WL) of the base elements 242, 232 in
certain medial portions 220d, 220f, etc. may be greater than the
width (WU, WL) of the base elements 242, 232 in certain lateral
portions 220e, 220g, etc.
[0078] In certain embodiments, for example referring to FIG. 5D,
the width (WL, WU) of adjacent upper or lower base elements 232,
242 need not be the same. As shown, the width WL' of a first base
element 232' is less than the width WL'' of an adjacent base
element 232''. Further, the width (WU, WL) of any individual base
element 242, 232 need not be constant. For example, the width (WU,
WL) of a base element 242, 232 may vary along the elongate axis of
the elongate channel 230, 240.
[0079] Another parameter shown in FIG. 4 that affects the
performance of the outsole portion 220 is the angle (A) that the
sidewall elements 234, 244 make to the top layer 222. Thus,
according to certain aspects, the angle (A) of the sidewall
elements 234, 244 from the upper base elements 242 may range from
approximately 50 degrees to approximately 130 degrees. If the
sidewall angle (A) is from 50 degrees to just less than 90 degrees
from the base elements 242, the channel 240 may be considered to
have a "splayed" configuration. At 90 degrees the sidewalls 234,
244 are vertical and the cross-section of the channels 230, 240
forms a square wave. At greater than 90 degrees, for example as
shown in FIG. 5E, the sidewalls 234, 244 of each channel 230, 240
converge toward each other in what might be referred to as a
"knock-kneed" configuration. To a certain extent it is expected
that the more vertical are the sidewalls 234, 244, the greater may
be the "trip point." Thus, for channels 230, 240 having a "splayed"
section (see FIG. 4), the angle (A) of the sidewalls 234, 244 may
range from approximately 50 degrees to less than 90 degrees or,
more limited, from approximately 65 degrees to approximately 85
degrees. According to certain embodiments, the angle (A) of the
sidewalls 234, 244 may be greater than approximately 70 degrees.
For channels 230, 240 having a "knock-kneed" section (see FIG. 5E),
the angle (A) of the sidewalls 234, 244 may range from greater than
90 degrees to approximately 130 degrees or, more limited, from
approximately 115 degrees to approximately 95 degrees. According to
certain embodiments, the angle (A) of the sidewalls 234, 244 may be
less than approximately 110 degrees. In some embodiments, the
angles (A) of the sidewalls 234, 234 need not be the same for both
sidewalls, such that the cross-section of the channel 230, 240
would be non-symmetric.
[0080] Representative geometries for select outsole portions are
presented in Table I (with reference to FIG. 4). The embodiments
having heights of 6.0 mm may be most suitable for use in the
forefoot portions 220a of the outsole structure 210. The
embodiments having heights of 10.0 mm may be most suitable for use
in the heel portions 220c of the outsole structure 210. The
embodiments having a thicker lower base element provide additional
tread thickness for enhanced durability. These embodiments, with
heights of 7.5 mm, may be suitable for use in the forefoot portion
220a and/or the heel portion 220c. It is to be understood that
depending upon the specific application and the expected impact
loads, these and other geometries, as would be apparent to persons
of skill in the art given the benefit of this disclosure, could be
used in any portion of the outsole structure.
TABLE-US-00001 TABLE I Representative Geometries for Certain
Embodiments Upper Lower Side- Base Upper Base Lower wall Element
Base Element Base Thick- Thick- Element Thick- Element Angle ness
ness Width ness Width Height (A) (TS) (TU) (WU) (TL) (WL) (H)
Example (deg) (mm) (mm) (mm) (mm) (mm) (mm) 1 70 1.0 1.0 3.0 1.0
3.0 6.0 2 74 1.0 1.0 3.0 1.0 3.0 6.0 3 82 1.0 1.0 3.0 1.0 3.0 6.0 4
83 1.0 1.0 3.0 1.0 3.0 6.0 5 85 1.0 1.0 3.0 1.0 3.0 6.0 6 70 1.0
1.0 3.0 1.0 1.25 6.0 7 71 1.0 1.0 3.0 1.0 1.25 6.0 8 78 1.0 1.0 3.0
1.0 1.25 6.0 9 70 1.1 1.1 3.0 1.1 3.0 6.0 10 70 1.25 1.0 3.0 1.0
1.25 6.0 11 70 1.25 1.25 3.0 1.25 1.25 6.0 12 70 1.25 1.25 3.0 1.25
3.0 6.0 13 70 1.0 1.0 3.0 2.5 1.25 7.5 14 70 1.5 1.5 3.0 2.5 1.25
7.5 15 70 1.0 1.0 3.0 1.0 3.0 10.0 16 70 1.5 1.5 3.0 1.5 3.0 10.0
17 85 1.0 1.0 3.0 1.0 3.0 10.0 18 85 1.5 1.5 3.0 1.5 3.0 10.0 19 73
1.0 1.0 3.0 1.0 3.0 6.0 20 70 1.2 1.2 3.0 1.2 3.0 6.0 21 70 1.5 1.5
3.8 2.7 1.25 6.0 22 70 1.5 1.5 6.8 2.7 1.25 6.0 23 70 1.5 2.2 1.6
2.7 1.25 9.0
[0081] Referring in general to FIG. 4 and also to FIGS. 6A and 6B,
the upper base elements 242 are spaced apart from one another a
distance (DU), and the lower base elements 232 are spaced apart
from one another a distance (DL). Referring to FIG. 4, the distance
DU is shown as equal to the distance DL. For other embodiments, DU
need not equal DL. Typically, the distance (DU, DL) between
adjacent spaced apart base elements 232, 242 will be constant, such
that the base elements 232, 242 are equally spaced from one
another. For example, referring to FIG. 6A, the spacing DL between
a first base element 232' and a second adjacent base element 232''
is the same as the spacing DL between the second base element 232''
and a third base element 232''', and so on. Optionally, however,
the distance (DU, DL) between the spaced apart, adjacent base
elements 242, 232 need not be constant. Referring now to FIG. 6B,
according to certain embodiments, base elements 232', 232'', 232'''
may be non-equally spaced from one another, i.e., the spacing DL'
between a first base element 232' and a second base element 232'
may be greater than the spacing DL'' between the second base
element 232'' and a third base element 232'''. The spacing (DU, DL)
between the base elements 242, 232 may range from approximately 3.0
mm to approximately 10.0 mm. In order to minimize the weight of the
outsole portion 220, the spacing (DU, DL) between the base elements
232, 242 may range from approximately 5.0 mm to approximately 10.0
mm or, more limited, from approximately 6.0 mm to approximately 8.0
mm. In order to increase the stiffness of the outsole portion 220,
the spacing (DU, DL) between the base elements 232, 242 may range
from approximately 3.0 mm to approximately 6.0 mm or, more limited,
from approximately 4.0 mm to approximately 5.0 mm.
[0082] According to other aspects, the spacing (DU, DL) of the base
elements 232, 242 between any two adjacent base elements may be
constant along the elongated length of the base elements 232, 242
(and, thus, along the elongated length of the channels 230, 240),
such that adjacent base elements (and adjacent channels) are
arranged parallel (or substantially parallel) to one another.
Optionally, however, the spacing (DU, DL) of the base elements 232,
242 need not be constant along the elongated length of the base
elements, such that the base elements 232, 242 (and adjacent
channels) may diverge from and/or converge toward one another. For
example, referring to FIG. 9C, the spacing between upper base
elements 242 decreases along the elongated length of the elements
242, i.e., DUi is greater than DU.sub.2.
[0083] According to certain aspects of the invention, a plurality
of the alternating upper and/or lower channels 230, 240 may
undulate in the horizontal plane of the outsole structure 210. As
shown in FIGS. 1B, 3A and 3B, on the bottom surface of the outsole
portions 220, the lower base elements 232 and also the associated
downward-facing channels 240 undulate across the plane of the
outsole structure 210. Similarly, on the opposite, upper surface of
the outsole portions 220, the upper base elements 242 and the
associated channels 230 undulate across the plane of the outsole
structure 210. As noted above and referring to FIGS. 3A and 3B, the
plurality of upper base elements 242, in the aggregate, forms the
top layer 222. Similarly, the plurality of lower base elements 232,
in the aggregate, forms the bottom layer 224.
[0084] Referring to FIGS. 7A-7C and FIGS. 8A-8C, the undulating
channels 230, 240 and/or the base elements 232, 242 (when viewed
from above or from below) have a non-linear profile. In other
words, the elongate axis (see FIG. 7A) of an undulating channel
230, 240 is not a straight line, i.e., the elongate axis of the
undulating channel changes direction as the undulating channel 230,
240 extends from its first end 230a, 240a to its second end 230b,
240b. The undulations provide a three-dimensional aspect to the
sidewalls 234, 244 of the channels 230, 240. In the situation where
a channel and its sidewalls are non-undulating, i.e., a straight
channel, the walls of the channel are formed as flat plates.
Conversely, for undulating channels 230, 240 the sidewalls 234, 244
follow the undulations and are not flat. It is expected that this
out-of-plane geometry that is imposed on the sidewalls 234, 244 by
the undulations of the channels 230, 240 provides an additional
stiffening mechanism. In the general case, the undulating channels
230, 240 (when viewed from above or from below) may have a zigzag
profile, a sinusoidal profile, a sawtooth profile (i.e., an
asymmetric version of a zigzag profile), a circular profile or any
other curved or non-straight profile, whether regular or
irregular.
[0085] As shown in FIG. 7A, the undulating channels 240 and the
base elements 232 (when viewed from below) may have a zigzag
profile. It is to be understood, that when viewed perpendicular to
the plane of the sole, the undulating channels 230 and the base
elements 242 would also have a zigzag profile. Further, as can be
seen, the undulations of FIG. 7A are regular and cyclical. For
example, a base element 232, 242 (and thus, its associated channel
240, 230) may be formed with a regular zigzag configuration, in
that the period (p) and the amplitude (a) of the zigzag (in
particular, the period and amplitude of the elongate axis of the
zigzag) remain constant from the first end 232a to the second end
232b. By way of non-limiting examples, the period may range from
approximately 10.0 mm to approximately 30.0 mm or from
approximately 15.0 to approximately 25.0 mm. By way of non-limiting
examples, the amplitude may range from approximately 2.0 mm to
approximately 20.0 mm or from approximately 5.0 to approximately
15.0 mm.
[0086] Optionally, the undulations in the plane of the sole may be
irregular or even random. For example, as shown in FIG. 7B, the
amplitude (a) of the elongate axis of the zigzag could vary--the
amplitude (a) of the zigzag could increase and/or decrease--as the
base elements 242 extend from the first ends 242a to the second
ends 242b of the base elements 242 and the associated channel 230
extends from the first end 230a to the second end 230b of the
channel 230. In FIG. 7B the amplitude is ai at end 242a and has
decreased to a.sub.2 at end 242b, while the period p has remained
constant. As shown in FIG. 7C, the period (p) of the elongate axis
of the zigzag could vary--the frequency of the zigzags could
increase and/or decrease--as the base elements 232 and the
associated channel 240 extend from the first ends 232a, 240a to the
second ends 232b, 240b. In FIG. 7C the period pi is greater than
the period p.sub.2, while the amplitude (a) has remained constant.
In the general case, the undulating channels 230, 240 (when viewed
from above or from below) may have a zigzag profile, a sinusoidal
profile, a sawtooth profile (i.e., an asymmetric version of a
zigzag profile), a circular profile or any other curved or
non-straight profile.
[0087] As shown in FIG. 8A, the undulating channels 240 and the
base elements 232 (when viewed from below) may have a sinusoidal
profile. Further, the undulations of FIG. 8A are regular and
cyclical, although, as described above with respect to the zigzag
channels of FIGS. 7A-7C, the period (p) and/or the amplitude (a) of
the sinusoidal undulations need not be regular. Similarly, the
undulating channels 230 and the base elements 242 (when viewed
perpendicular to the plane of the sole) may have a sinusoidal
profile.
[0088] FIG. 8B illustrates an alternative embodiment of an outsole
portion 220 wherein the base elements 232, 242 are formed with both
sinusoidal and zigzag shapes. In this particular configuration, the
sinusoidally-shaped base elements 242' alternate with zigzag-shaped
base elements 242''. Channel 230 is an undulating channel, but one
of its sidewalls follows a sinusoidal path and the other of its
sidewalls follows a zigzag path. Similarly, the undulating channels
240 and the base elements 232 (when viewed from below) may also be
formed with alternating sinusoidal and zigzag shapes.
[0089] FIG. 8C illustrates another alternative embodiment of an
outsole portion 220 wherein the base elements 232, 242 are formed
as rings. In this particular configuration, the ring-shaped base
elements 242 and ring-shaped channels 230 undulate around a closed
loop. In other words, the elongate axis of a circular (or
elliptical, ovoid, etc.) channel 230, 240 is not a straight line.
Rather, the elongate axis of this circular undulating channel
changes direction as the undulating channel 230, 240 extends from a
first end to a second end. In the case of a closed loop, the first
and second ends are coincident. Just as with the zigzag or
sinusoidal undulations, the circular undulations provide a
three-dimensional aspect to the sidewalls 234, 244 of the channels
230, 240. In certain alternative embodiments, the loop need not be
closed, such that the base elements 232, 242 and channels 230, 240
may have a C-shaped profile, a hemispherical profile, a spiral
profile, etc. (when viewed from above or below).
[0090] Thus, according to certain other aspects, a plurality of the
upper base elements 242 may undulate in the substantially
horizontal plane of the upper layer 222. Similarly, a plurality of
the lower base elements 232 may undulate in the horizontal plane of
the lower layer 224. In other words, when viewed from above (or
below), each of the base elements 242, 232 that forms the top or
bottom layer 222, 224 of the outsole portion 220 may have a
nonlinear two-dimensional aspect along their elongated axis. In
certain embodiments, for example as shown in FIGS. 3A and 3B, the
undulating features of each of the base elements 232, 242 of the
top and/or bottom layers 222, 224 of the outsole portions 220 are
identical. In other words, each of the base elements 242 of the top
layer 222 of an outsole portion 220 has an identical nonlinear
configuration. Alternatively, the base elements 242 of the top
layer 222 need not have identical configurations.
[0091] Additionally, the undulating features of the base elements
242 of the top layer 222 may be identical to the undulating
features of the base elements 232 of the bottom layer 224. However,
in certain embodiments, the undulations of the upper base elements
242 need not be the same as the undulations of the lower base
elements 232. Thus, in an example embodiment, the upper base
elements 242 (when viewed perpendicular to the plane of the sole)
may have a zigzag configuration, while the lower base elements 232
(when viewed from below) may be smoothly sinusoidal. As another
example, the undulations of the upper base elements 242 may have an
amplitude and/or a period that differs from the amplitude and/or
period of the undulations of the lower base elements 232. Even
further, the lower base elements 232 may undulate in the plane of
the sole, while the upper base elements 242 do not (or vice versa).
Thus, for example, as shown in FIG. 14A, the lower base elements
232 may undulate (as seen from below), while the upper base
elements may extend straight without undulating across the outsole
portion 220.
[0092] As even another alternative configuration and referring to
FIG. 14B, the elongated axis of one or both of the lower base
elements 232 and the upper base elements 242 may extend without
undulating across the outsole portions 220 while the sidewalls 234,
244 undulate. This configuration is possible because, while the
centerline (i.e., the elongated axis) of the base elements 232, 242
remains straight, the lengthwise edges 232c, 232d, 242c, 242d of
the base elements 232, 242 undulate. The undulating lengthwise
edges 232c, 232c, 242c, 242d provide a three-dimensional aspect to
the sidewalls 234, 244 of the channels 230, 240 as the sidewalls
extend down the length of the channels. The vertical slopes of the
sidewalls 234, 244 may vary along the length of the channels. The
horizontal slopes of the sidewalls 234, 244 may vary along the
length of the channels. Picture a plane flying down a narrow
valley, wherein to hug the sides of the hills forming the valley
the plane must pitch and roll. In this manner, a twisting,
rippling, rolling, three-dimensional geometry may be imposed on the
sidewalls 234, 244 to thereby provide an additional stiffening
mechanism.
[0093] With such non-symmetric undulating configurations, the
sidewalls 234, 244 connecting the upper base elements 242 to the
lower base elements 232 would generally have complex, curvilinear
configurations. The sidewall elements 234, 244 may generally be
considered to be planar, plate-like elements, i.e., having a length
and/or a width that are considerably greater than their thickness
(TS). However, it is to be understood that the sidewall elements
234, 244 may be flat, curved in one dimension (such as a
cylindrical sidewall of a can would be) or doubly curved (such as a
portion of a sphere). Most typically, the sidewalls 234, 244 will
be linear in the vertical cross-sectional plane of the outsole
structure 210 and either linear or curved along the length of the
undulating channel 230, 240 (i.e., to follow the linear or curved
undulations of the undulating base elements 232, 242 of the top and
bottom layers 222, 224).
[0094] The top layer 222 and the bottom layer 224, and their
associated undulating base elements 242, 232, may remain
essentially planar. A person of ordinary skill in the art would
understand that "essentially planar," in the context of the upper
and lower layers 222, 224, encompasses slight curvatures or other
out-of-plane geometries as would be in keeping with a sole
structure 200 following the contours of a foot and allowing for a
comfortable and/or efficient gait. Thus, when viewed from the side,
the individual base elements 242, 232 may also be essentially
planar--the undulations of the base elements 232, 242 lie in the
plane of the top (or bottom) layer 222, 224. In other words, as
with the top (or bottom) layer 222, 224 as a whole, each base
element 232, 242 may be essentially planar, with slight curvatures
or out-of-plane geometries as would be in keeping with a sole
structure following the contours of a foot.
[0095] Alternatively, as shown in FIGS. 15A and 15B, undulations in
the height (H) of the channels 230, 240 along the lengths of the
channels 230, 240 may be reflected in vertical undulations of the
lower base elements 232 (when viewed from the side, i.e., crosswise
to the channels). As with the undulation of the base elements
in-the-plane of the sole, the undulations of the base elements
out-of-the-plane of the sole, the undulations may be regular or
irregular and of any shape (zigzag, sinusoidal, stepped, jagged,
rounded, angular, etc.). Due to the vertical undulations, the base
elements 232 may have areas 233 that contact the ground and raised
areas 235 that are displaced heightwise from the ground. Even
further, the raised areas 235, i.e., those areas of the lower base
elements 232 that are displaced heightwise from the ground in a
"no-load" condition (refer to FIG. 15A), may be displaced downward
when the sole portion is subjected to a pressure load (p) such that
some or all of the previously raised areas come into contact with
the ground (refer to FIG. 15B). Thus, according to some
embodiments, the traction area may vary as a function of pressure
load.
[0096] As discussed above and referring, for example, back to FIG.
4, the base elements 232, 242 may have a constant width or a
non-constant width (WU, WL). Thus, an undulating base element may
have a constant width. For example, as shown in FIG. 7A, a first
edge 232c of the undulating base element 232 may have a zigzag
profile and a second edge 232d of the undulating base element 232
may be formed with an identical zigzag profile. Alternatively, the
undulating base elements 232, 242 may have a varying width (WU,
WL). For example, as shown in FIG. 9A, a first edge 232c of the
undulating base element 232 may have a relatively deep zigzag
profile and the second edge 232d of the undulating base element 232
may have a shallower zigzag feature, such that the width (WL) of
the undulating base element 232 increases and then decreases within
the zigzag wavelength unit. As even another non-limiting example,
referring to FIG. 9B, an undulating base element 242 may have a
zigzag profile along a first edge 242c and half-sinusoidal profile
along a second edge 242d, wherein the wavelength of the zigzag
profile of the first edge 242c is the same as the wavelength of the
half-sinusoidal profile along the second edge 242d. It can be seen
that the width (WU) of the undulating base element 242 increases
and then decreases nonlinearly within the zigzag wavelength unit.
As a further non-limiting example, as shown in FIG. 9C, the
profiles along the first and second edges 242c, 242d of an
undulating base element 242 could be identical (for example, zigzag
profiles), with the exception that, rather than running parallel to
one another from the first end 242a to the second end 242b of the
base element 242, the edges 242c, 242d gradually diverge from one
another. Thus, in this example, the width (WU) of the base element
242 gradually increases as the element extends from the first end
242a to the second end 242b. Given the benefit of this disclosure,
it becomes apparent that variations and/or combinations of these
features may be combined.
[0097] Referring back to FIG. 1B, the outsole structure 210 could
be formed as a single outsole portion 220. In this example, as
viewed from below, the lower channels 240 of the outsole portion
220 undulate across the outsole structure 210 from the medial side
18 to the lateral side 17, and the plurality of lower channels 240
are arrayed in a series from the toe 14 to the heel 15. If viewed
from above, the upper channels 230 of the outsole portion 220 would
also be seen to undulate across the outsole structure 210 from the
medial side 18 to the lateral side 17, and the plurality of upper
channels 230 would be seen to be arrayed from the toe 14 to the
heel 15. In this embodiment, at least a majority of the channels
240 (and the channels 230) continuously extend essentially across
the outsole structure 210 from the lateral side 17 to the medial
side 18 (e.g., at least 90% of this distance, and in some examples,
at least 95% of this distance).
[0098] In certain embodiments, for example as shown in FIG. 1B, the
channels 240 extend from their first ends 240a to their second ends
240b in a generally lateral-to-medial direction. Alternatively, it
may be desirable for the channels 230, 240 to extend at an angle to
the lateral-to-medial direction (see, e.g., outsole portion 220a in
FIG. 11) or even in a generally longitudinal direction.
[0099] As noted above and referring to FIGS. 10, 11 and 12,
according to certain aspects, the outsole structure 210 may include
one or more outsole portions 220. Referring to FIG. 10, a first
outsole portion 220h may be located in the forefoot region 11, a
second outsole portion 220i may be located in the midfoot region
12, and a third outsole portion 220j may be located in the heel
region 13. In such case, the first outsole portion 220h may be
configured to be thinner and lighter weight than the third outsole
portion 220j. According to certain embodiments, the third outsole
portion 220j may be configured to react to greater impact loads
than the first outsole portion 220h. Referring to FIG. 11, a first
outsole portion 220k is located in the forefoot region and a second
outsole portion 220l is located in the heel region. Referring to
FIG. 12, a first outsole portion 220m is located in the forefoot
and the midfoot regions, a second outsole portion 220n is located
in the heel region and a third outsole portion 220p is located
beneath the great toe in the forefoot region. Each of these three
outsole portions 220m, 220n, 220p are provided with different
geometries (TS, TU, TL, WU, WL, DU, DL, profiles, periods,
amplitudes, etc.) so that these portions provide different
impact-attenuation properties. In this way, the outsole structure
210 may be tailored to the expected conditions of use.
[0100] The one or more outsole portion 220a, 220b, 220c, etc. may
cover at least a majority of the outsole area (e.g., at least 75%
of the area, or even at least 85% or more of the area) of the
outsole structure 210. Further, the one or more outsole portions
220 may be unitarily formed or, alternatively, the one or more
outsole portions 220 may be made from different and/or separate
pieces of material that are cemented or otherwise engaged to one
another or with other portions of the outsole structure 210, if
any.
[0101] Other conventional outsole configurations may also be
provided within the outsole structure 210 where the one or more
outsole regions 220, as disclosed herein, are not located. Thus, if
desired, one or more regions of the outsole structure 210 may be
provided without any channels 230, 240 or without any undulating
elements 232, 242 without departing from the invention (see, for
example, FIG. 11). These additional conventional outsole
configurations, when present, may be unitarily formed with the
outsole portions 220 as disclosed herein, or these additional
conventional outsole configurations may be made from different
and/or separate pieces of material that are cemented or otherwise
engaged with the remainder of the outsole structure 210. These
other conventional outsole configurations of the outsole structure
210 may be provided with or without a tread pattern, so as to give
different traction, wear resistance, aesthetic appearance, logos or
brand identifying information, and/or other desired properties or
characteristics to various portions of the outsole structure
210.
[0102] The outsole portions 220 may further include a frame member
226 that extends around the perimeter of the outsole portion 220
and serves to connect the ends of the channels 230, 240 and/or the
base elements 232, 242 together. The frame member 226 may lie in
the same plane as the top layer 222 or the bottom layer 224. When
the outsole structure 210 includes but a single outsole portion
220, the frame member 226 may extend around the perimeter of the
outsole structure 210, which generally will coincide with the
perimeter of the article of footwear.
[0103] Additionally, in one aspect, the outsole structure 210 may
be a cupsole, formed as a single piece. According to this aspect,
the outsole structure 210 may include a perimeter element 216
extending along at least a portion of the perimeter of the outsole
structure 210. Typically, the perimeter element 216 forms a flange
or sidewall that extends upward from the top layer 222 to form a
structure that may cup and assist in retaining the upper 100 and/or
the midsole 214, if any. The perimeter element 216 may be unitarily
formed or co-molded with, or otherwise attached to, the top layer
222 or bottom layer 224. Further, the perimeter element 216 may
also serve as a frame member 226 that connects the ends of the
channels 230, 240 and/or base members 232, 242 together.
[0104] In operation, as the outsole structure 210 is initially
compressed, energy is absorbed by the outsole structure's
impact-attenuation system. As the outsole structure 210 is
compressed even more, additional energy is absorbed by the system.
For high-impact loading, it would be desirable to have a
significant amount of energy absorbed by the system without the
user's foot experiencing high impact loads. The disclosed
impact-attenuation system provides a mechanism to absorb energy
while at the same time minimizing or ameliorating the loads
experienced by a user during the impact. As described below, the
multi-regime outsole portions 220 disclosed herein may absorb
significant amounts of energy, for example, as compared to
conventional foamed midsoles with conventional outsoles, while
minimizing or reducing the loads experienced by the user during the
impact event.
[0105] Examples of energy absorption curves of various outsole
portions 220 are shown in FIG. 13. This figure shows the total
energy absorbed, based on finite element analyses, by the outsole
portion per unit area as a function of pressure. As noted above,
the pressure is determined using the overall gross area of the sole
portion to which the load is applied, not just the specific net
area of those elements of the sole portion contacted by the loading
fixture (e.g., the area of just the upper base elements 242 of the
channels). As a control, a 6 mm tall polyurethane foam block
(injected Phylon) was tested in compression (curve X). In the
pressure range of interest, the foam block essentially exhibits a
linear response--as the pressure increases, the total energy per
unit area proportionally increases. Three example energy absorption
curves (A, B and C) for various outsole portion configurations
according to the present disclosure are also presented in FIG. 13.
Curve A is associated with sample 19 from Table I; curve B is
associated with sample 20 from Table I; and curve C is associated
with sample 5 from Table I.
[0106] Examining curve (A), it is seen that its "trip point" is
from 300 kPa to 350 kPa, and that without exceeding the pressure of
350 kPa the outsole portion 220 associated with curve A absorbs
from 700 J/mm.sup.2 to 800 J/mm.sup.2. In comparison, at a pressure
of 350 kPa the foam block absorbs only about 330 J/mm.sup.2. In
other words, at a pressure of 350 kPa, the outsole portion
associated with curve A absorbs more than twice (approximately 2.3
times) the energy per unit area as the control foam block. Even
further, when the "trip point" pressure value is first reached
(i.e., its first occurrence), the energy per unit area is
approximately 300 J/mm.sup.2, and when the "trip point" pressure
value is next reached (i.e., its second occurrence), the energy per
unit area is approximately 750 J/mm.sup.2. Thus, from the first
occurrence to the second occurrence of the "trip point" pressure
value, the amount of energy absorbed by the outsole portion 220
associated with curve A has more than doubled.
[0107] Examining curve (B), it is seen that its "trip point" is
from 450 kPa to 500 kPa, and that at a pressure of approximately
470 kPa the outsole portion 220 associated with curve B absorbs
approximately 1000 J/mm.sup.2--approximately 1.8 times the energy
per unit area as the control foam block. Further, at a pressure of
550 kPa, the outsole portion absorbs from 1000 J/mm.sup.2 to 1100
J/mm.sup.2. In comparison, at a pressure of 550 kPa the foam block
absorbs only about 740 J/mm.sup.2. Even further, when the "trip
point" pressure value is first reached (i.e., its first
occurrence), the energy per unit area of curve B is approximately
450 J/mm.sup.2, and when the "trip point" pressure value is next
reached (i.e., its second occurrence), the energy per unit area is
approximately 1000 J/mm.sup.2. Thus, from the first occurrence to
the second occurrence of the "trip point" pressure value, the
amount of energy absorbed by the outsole portion 220 associated
with curve B has increased by approximately 70%.
[0108] Examining curve (C), it is seen that its "trip point" is
from 600 kPa to 650 kPa, and that at a pressure of 650 kPa the
outsole portion 220 associated with curve C absorbs approximately
1200 J/mm.sup.2--approximately 26% more energy per unit area as the
control foam block. When the "trip point" pressure value is first
reached (i.e., its first occurrence), the energy per unit area of
curve C is approximately 600 J/mm.sup.2, and when the "trip point"
pressure value is next reached (i.e., its second occurrence), the
energy per unit area is approximately 1150 J/mm.sup.2. Thus, from
the first occurrence to the second occurrence of the "trip point"
pressure value, the amount of energy absorbed by the outsole
portion 220 associated with curve C has increased by approximately
90%.
[0109] Another way of viewing the curves of FIG. 13 is to consider
the total energy per unit area that must be absorbed due to any
particular impact loading event. If the total energy from the
impact loading event is, for example, approximately 700 J/mm.sup.2,
then the outsole portion 220 associated with curve A could absorb
that amount of energy without ever exceeding a pressure loading of
350 kPa (approximately 335 kPa). In contrast, in order for the foam
block (curve X) to absorb that amount of energy, a pressure loading
exceeding 500 kPa (approximately 530 kPa) would be experienced.
Thus, the outsole portion 220 associated with curve A achieves a
pressure loading reduction of approximately 60% compared to the
foam block for this scenario. Upon further examination of FIG. 13,
it can be conservatively determined that the outsole portion 220
associated with curve A is capable of absorbing an energy per unit
area of at least 600 J/mm.sup.2 without exceeding a pressure of 350
kPa; that the outsole portion 220 associated with curve B is
capable of absorbing an energy per unit area of at least 1000
J/mm.sup.2 without exceeding a pressure of 500 kPa; and that the
outsole portion 220 associated with curve C is capable of absorbing
an energy per unit area of at least 1200 J/mm.sup.2 without
exceeding a pressure of 700 kPa.
[0110] The outsole structure 210 may be formed of conventional
outsole materials, such as natural or synthetic rubber or a
combination thereof. The material may be solid, foamed, filled,
etc. or a combination thereof. One particular rubber may be a solid
rubber having a Shore A hardness of 74-80. Another particular
composite rubber mixture may include approximately 75% natural
rubber and 25% synthetic rubber. The synthetic rubber could include
a styrene-butadiene rubber. By way of non-limiting examples, other
suitable polymeric materials for the outsole include plastics, such
as PEBAX.RTM. (a poly-ether-block co-polyamide polymer available
from Atofina Corporation of Puteaux, France), silicone,
thermoplastic polyurethane (TPU), polypropylene, polyethylene,
ethylvinylacetate, and styrene ethylbutylene styrene, etc.
Optionally, the material of the outsole structure 210 may also
include fillers or other components to tailor its wear, durability,
abrasion-resistance, compressibility, stiffness and/or strength
properties. Thus, for example, the outsole structure 210 may
include reinforcing fibers, such as carbon fibers, glass fibers,
graphite fibers, aramid fibers, basalt fibers, etc.
[0111] While any desired materials may be used for the outsole
structure 210, in at least some examples, the rubber material of
the outsole structure 210 may be somewhat softer than some
conventional outsole materials (e.g., 50-55 Shore A rubber may be
used), to additionally help provide the desired multi-regime
characteristics. Optionally, if desired, a harder material (e.g.,
60-65 Shore A rubber) may be used in the heel region and/or in
certain medial regions.
[0112] Further, multiple different materials may be used to form
the outsole structure 210 and/or the various outsole portions 220.
For example, a first material may be used for the forefoot region
11 and a second material may be used in the heel region 13.
Alternatively, a first material may be used to form the
ground-contacting bottom layer 224 and a second material may be
used to form the sidewalls 234, 244 and/or the top layer 222. The
outsole structure 210 could be unitarily molded, co-molded,
laminated, adhesively assembled, etc. As one non-limiting example,
the ground-contacting layer 224 (or a portion of the
ground-contacting bottom layer) could be formed separately from the
sidewalls 234, 244 and/or the top layer 222 and subsequently
integrated therewith.
[0113] The ground-contacting bottom layer 224 may be formed of a
single material. Optionally, the ground-contacting bottom layer 224
may be formed of a plurality of sub-layers. For example, a
relatively pliable layer may be paired with a more durable,
abrasion resistant layer. By way of non-limiting examples, the
abrasion resistant layer may be co-molded, laminated, adhesively
attached or applied as a coating. Additionally, the material
forming the abrasion resistant layer of the outsole structure 210
may be textured (or include texturing inclusions) to impart
enhanced traction and slip resistance.
[0114] Further, with respect to another aspect of the disclosure,
at least a portion of the outsole structure 210 may be provided
with a grip enhancing material 218 to further enhance traction and
slip resistance (see e.g., FIG. 1A). The grip enhancing material
218 may provide improved gripping properties as the foot moves and
rolls along the skateboard, while the other portions of the outsole
structure 210 may provide long term durability and wear resistance.
Further, the grip enhancing material 218 may allow a larger area of
the footwear to maintain contact with the skateboard as the foot
moves and rolls along the board. Thus, for example, a relatively
soft rubber or rubber-like component or a relatively soft
thermoplastic material, such as a thermoplastic polyurethane (TPU),
may be provided along the perimeter portion of forefoot region 11
of the outsole structure 210. In one particular embodiment, a
softer durometer rubber may form an outer layer of the outsole
structure 210 (e.g., a rubber having a hardness of 60 to 75 Shore
A, possibly of 60 to 70 Shore A, and possibly of 64 to 70 Shore A),
with a harder durometer rubber forming an inner layer (e.g., a
rubber having a hardness of 70 to 90 Shore A, and possibly of 75 to
88 Shore A). Optionally, the enhanced gripping material may be
co-molded, adhesively bonded, coated or otherwise provided on the
outsole structure 210.
[0115] According to certain aspects and referring back to FIG. 5F,
the sole structure 200 may further include a strobel 260. For
instance, the top surface of the top layer 222 of the outsole
structure 210 may be glued or otherwise affixed to a strobel 260.
To assist in the attachment of the strobel 260 to the top layer
222, the width (WU) of the base elements 242 forming the top layer
222 may range from approximately 1.0 mm to approximately 5.0 mm,
from approximately 2.0 mm to approximately 4.0 mm, or even from
approximately 2.5 mm to approximately 3.5 mm. In certain
embodiments, a width WU of from approximately 2.8 mm to
approximately 3.2 mm may provide a suitable platform to which a
strobel 260 may be glued or otherwise affixed.
[0116] Typically, a strobel 260 is a sole-shaped element that may
include thin flexible materials, thicker and/or stiffer materials,
compressible materials or a combination thereof to improve
stability, flexibility and/or comfort. For example, the strobel 260
may include a cloth material, such as a woven or non-woven cloth
supplied by Texon International, or a thin sheet of EVA foam for a
more cushioned feel. An example strobel may be an EB-Strobel. The
strobel 260 may have a thickness ranging from approximately 4.0 mm
to approximately 10.0 mm, from approximately 5.0 to approximately
9.0 mm or even from approximately 6.0 to approximately 8.0 mm. For
some applications, the strobel 260 would be thicker in the heel
region than in the forefoot region. For certain applications, the
strobel 260 may only be provided in the forefoot region, the
midfoot region, the heel region, or select portions or combinations
of these regions. A foam sockliner 212 such as described above, may
be provided on top of the strobel 260.
[0117] It is to be understood that the addition of a strobel 260 or
a sockliner 212 (or any other structure) will generally affect the
stiffness characteristics of the outsole structure 210. Thus, the
above discussion of outsole portions 220 and their stiffness
characteristics is with respect to the outsole portions 220, in and
of themselves, i.e., without the inclusion of any additional
structure as may be part of the outsole structure 210 as a
whole.
[0118] According to even other aspects of this disclosure and
referring again to FIG. 5F, one or more fill elements 250, such as
polymeric foam inserts, rubber-type inserts or air bladders, may be
provided within the upward-facing channels 230 of the outsole
portions 220. These fill elements 250 may contact and/or stabilize
the sidewalls 234, 244 or portions of the sidewall. For example, a
majority of the sidewall area of one or more of the upward-facing
channels 230 may be in contact with relatively stiff, compressible,
foam. As another example, only the portion of the sidewall 234, 244
closest to the top layer 222, i.e., the portion of the sidewall
234, 244 away from the ground-contacting, bottom layer 224 may be
in contact with a fill element 250. Providing fill elements 250 may
allow the compressive loads to be further diffused, while at the
same time stabilizing portions of the outsole structure 220.
[0119] For example, if desired, fill elements 250 may include an
impact-attenuating material that at least partially fills, and in
some instances completely fills, at least some of the
upwardly-facing channels 230 of an outsole region 220. This
additional impact-attenuating material, which may be somewhat
softer than the material from which the channel is constructed, can
also help provide a smooth and comfortable surface for user foot
contact while still transmitting forces to the bottom layer 224 and
to the downwardly-facing channels 240. The impact-attenuating
material may include relatively soft polyurethane or other foam
material. The fill elements 250, if any, may be co-molded in
conventional manners along with the molding process used to form
the outsole structure 210 or the fill elements 250 may applied to
the outsole structure 210 in a separate manufacturing operation.
The strobel 260 and the fill elements 250 are separate elements
that may be provided independently of each other.
[0120] Even further as shown in FIG. 5G, the outsole structure 210
may optionally be provided with an impermeable layer 270 that is
sealed to the top surface of the top layer 222, to the frame member
216, if any (see e.g., FIG. 11) and/or to the perimeter member 226
(see e.g., FIG. 11) of the outsole structure 210. Such an
impermeable layer 270 need not extend completely over the entire
outsole structure 210, but may be located in one or more regions
(11, 12, 13, etc.) or portions of regions of the outsole structure
210. As a non-limiting example, the impermeable layer 270 may be
located in the heel region 13 and/or in the forefoot region 13, but
not in the midfoot region 12. The upper layer-to-outsole seal may
form a fluid-tight seal that defines one or more fluid-tight
chambers 272. These fluid-tight chambers 272 are defined by the
upper channels 230 and the impermeable layer 270. The fluid-tight
chambers 272 may accommodate and retain air (or other gas,
positively pressurized or not) or a liquid (for example, water,
positively pressurized or not). Thus, in essence, an outsole
structure 210 with a sealed impermeable layer 270 would form at
least one interior chamber 272 that may function as a fluid bladder
and thereby assist in carrying and distributing loads.
[0121] Thus, from the above disclosure it can be seen that the
enhanced impact-attenuation system due to the outsole portions 220
as disclosed herein provides better impact protection, while not
sacrificing feel, for a wearer of the article of footwear. During
use, one or more of the channels 230, 240 provide support for the
wearer's foot. The channels 230, 240 in a first, unbuckled
configuration carry or react at least some of the vertical,
compressive load transmitted from the wearer to the ground. Thus,
according to certain aspects of the disclosure, the channels 230,
240 in a first pressure-versus-displacement regime are designed to
elastically react vertical compressive loads. In this first regime,
the pressure versus displacement curve may be relatively stiff such
that the wearer is able to get a good "feel" for the engaged
surface. When a "trip point" load is reached, the channels 230, 240
are designed to assume a second, buckled, configuration. In such a
second pressure-versus-displacement regime, the channels 230, 240
are designed to compliantly absorb additional impact energy without
substantially any additional increase in load (for a given change
in displacement). At some point in the post "trip point" regime,
the buckling of the sidewalls 234, 244 will be at least partially
arrested or physically limited and the stiffness of the outsole
portion 220 will start to increase. For example, two adjacent
sidewalls 234, 244 may lateral deflect until they contact one
another, at which point, the lateral deflection of one sidewall
will serve to limit the lateral deflection of the other sidewall
(and vice versa). Upon release of the load, the channels 230, 240
return to their original configuration, without any permanent set
or deformation. If the impact energy to be dissipated is great
enough, the channels 230, 240 will eventually essentially "bottom
out," and the load experience by the wearer's foot in this third
pressure-versus-displacement regime may increase above the "trip
point" load.
[0122] The "trip point" load may be selected such that under normal
walking or usage conditions the "trip point" is not reached. In
other words, the channels 230, 240 may be designed with a high
enough "trip point" such that the "trip point" is only achieved
under relatively high impact loads. Further, the "trip point" may
be selected based on expected loading events and peak pressure
distributions under the foot. So, for example, for a skateboard
shoe a target "trip point" of 350 kPa (+/-50 kPa, +/-75 kPa, or
even +/-100 kPa) may be selected to accommodate expected loads
during high impact tricks in the forefoot region of the foot, while
a target "trip point" of 550 kPa (+/-50 kPa, +/-75 kPa, or even
+/-100 kPa) may be selected to accommodate expected loads during
high impact tricks in the heel region of the foot. Other "trip
points" could be selected based on the expected impact event.
[0123] The disclosed multi-stage or multi-zoned vertical stiffness
profile of this disclosed impact-attenuation system allows impact
loading associated with normal activities such as walking to be
reacted by the stiffer configuration of the outsole portions 220,
thereby providing greater "feel" for the ground during low impact
operation. The greater impact loading associated with jumping and
tricks may be partly reacted by the softer, buckled, configuration
of the outsole portions 220, thereby providing a "high-impact
cushioning system," i.e., a stiffness regime that provides superior
protection for the wearer during such high impact activities.
[0124] This disclosed impact-attenuation system allows the sole
structure 200 to be tailored to the specific application. The
stiffness and compression characteristics (and particularly, the
pressure-versus-displacement curves) of any particular outsole
portion 220 is a function not only of its material (as would be the
case with conventional cushions and foams) but also of its
geometry. Thus, in essence, the geometry of the outsole portions
220 may be selected so that a particular
pressure-versus-displacement characteristic may be achieved in the
first regime, a desired "trip point" may be design to, and the
post-buckling pressure-versus-displacement characteristics in the
second regime may be tailored so that the expected impact energy is
reacted without exceeding the desired "trip point" a second time.
For certain embodiments, as compared to a sole structure having a
solid foam midsole, the outsole portions 220 may be designed to be
initially stiffer, but then softer than a solid foam midsole sole
structure.
[0125] Thus, according to certain aspects, under expected
low-impact loading conditions, the outsole portions 220 could be
designed to act like a conventional, relatively stiff sole. Loads
reacted at the ground (or other engaged surface) would be
transmitted through the sole with relatively little attenuation
such that a user would "feel" the reaction loads. Under high-impact
loading conditions (i.e., when the "trip point" is reached), the
sidewalls 234, 244 could be designed to buckle, resulting in a
relatively short vertical displacement of the outsole portion 220
under a reduced (or possibly the same) pressure. During this
buckling, post "trip point" regime, the user would feel a softening
of the sole and experience a corresponding cushioning or
"sinking-in" feel. Although the user will lose some "feel" for the
ground during this "sinking-in" period, the loads experienced by
the user will be attenuated, thus protecting the user's foot from
injury. As the vertical displacement increases, at some point it is
expected that the user will start to experience increasing reaction
loads. Bottoming out occurs when the deflection due to buckling has
reached it maximum, at which point impact force attenuation would
be achieved by compression of the material of the outsole portion
220.
[0126] While the invention has been described with respect to
specific examples including presently preferred modes of carrying
out the invention, those skilled in the art, given the benefit of
this disclosure, will appreciate that there are numerous variations
and permutations of the above described structures, systems and
techniques that fall within the spirit and scope of the invention
as set forth above. Thus, for example, a wide variety of materials,
having various properties, i.e., flexibility, hardness, durability,
etc., may be used without departing from the invention. Finally,
all examples, whether preceded by "for example," "such as,"
"including," or other itemizing terms, or followed by "etc.," are
meant to be non-limiting examples, unless otherwise stated or
obvious from the context of the specification.
* * * * *