U.S. patent application number 11/270526 was filed with the patent office on 2007-05-10 for footwear sole assembly having spring mechanism.
This patent application is currently assigned to Fila Luxembourg S.A.R.L.. Invention is credited to Chris Brewer, Olivier Henrichot.
Application Number | 20070101617 11/270526 |
Document ID | / |
Family ID | 38002324 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070101617 |
Kind Code |
A1 |
Brewer; Chris ; et
al. |
May 10, 2007 |
Footwear sole assembly having spring mechanism
Abstract
A sole assembly which includes a heel cradle configured to
cradle a heel of a human foot when the human foot is rested within
the heel cradle, a rigid upper plate including a first part
connected to the heel cradle and a second part located farther from
the heel cradle than is the first part, a lower plate including a
first part of which is connected to the first part of the upper
plate and including a second part which is connected to the second
part of the upper plate, an oblong gap located between the upper
plate and lower plate and between the first and second parts of the
upper and lower plates. A sole assembly including an upper plate
and a lower plate stiffer than the upper plate and attached to the
upper plate so as to form an oblong gap. Also, a shoe including the
sole assembly.
Inventors: |
Brewer; Chris; (Baltimore,
MD) ; Henrichot; Olivier; (New York, NY) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Fila Luxembourg S.A.R.L.
Grand Duche du Luxembourg
LU
|
Family ID: |
38002324 |
Appl. No.: |
11/270526 |
Filed: |
November 10, 2005 |
Current U.S.
Class: |
36/103 |
Current CPC
Class: |
A43B 7/144 20130101;
A43B 13/12 20130101; A43B 7/08 20130101; A43B 13/026 20130101; A43B
13/183 20130101 |
Class at
Publication: |
036/103 |
International
Class: |
A43B 13/00 20060101
A43B013/00 |
Claims
1. A sole assembly comprising: a heel cradle configured to cradle a
heel of a human foot when the human foot is rested within the heel
cradle; an upper plate including a first part connected to the heel
cradle and a second part located farther from the heel cradle than
is the first part; a lower plate including a first part which is
connected to the first part of the upper plate and including a
second part which is connected to the second part of the upper
plate; an oblong gap located between the upper plate and lower
plate and between the first and second parts of the upper and lower
plates shaped such that a gap dimension between the upper and lower
plates in a first direction, measured from the first part of the
upper plate to the second part of the upper plate, is greater than
a gap dimension between the upper and lower plates in a second
direction which is perpendicular to the first direction.
2. The sole assembly of claim 1, further comprising at least one
insert attached to at least one of the upper plate and lower
plate.
3. The sole assembly of claim 2, wherein the at least one insert is
located in the lower plate.
4. The sole assembly of claim 3, wherein the at least one insert
includes a material with a stiffness greater than a stiffness of a
material comprising the lower plate.
5. The sole assembly of claim 4, wherein the at least one insert
comprises at least one of carbon fiber and poly-paraphenylene
terephthalamide.
6. The sole assembly of claim 4, wherein the insert is located
nearer to a medial side of the lower plate than to a lateral
side.
7. The sole assembly of claim 1, wherein the upper plate and lower
plate are comprised of different materials.
8. The sole assembly of claim 7, wherein the lower plate comprises
carbon fiber.
9. The sole assembly of claim 7, wherein the lower plate comprises
poly-paraphenylene terephthalamide.
10. The sole assembly of claim 1, wherein the heel cradle comprises
a different material than the upper plate.
11. The sole assembly of claim 1, wherein the heel cradle and upper
plate are a continuous piece of material.
12. The sole assembly of claim 11, wherein the heel cradle is
vented.
13. The sole assembly of claim 12, wherein the heel cradle is
partially directly supported by the upper plate and partially
directly supported by a cushion material.
14. The sole assembly of claim 1, wherein the upper plate is
asymmetrical about a vertical plane that passes through a center of
the heel cradle and a center of a toe of the sole assembly.
15. The sole assembly of claim 14, wherein the lower plate is
asymmetrical about a vertical plane that passes through a center of
the heel cradle and a center of a toe of the sole assembly.
16. The sole assembly of claim 15, wherein the lower plate has
vertical protrusions that support walls of the heel cradle.
17. The sole assembly of claim 1, wherein the lower plate includes
a cavity.
18. The sole assembly of claim 17, wherein the upper plate includes
a cavity at least partially overlapping the cavity of the lower
plate.
19. The sole assembly of claim 1, wherein a medial side of the
lower plate is stiffer than a lateral side of the lower plate.
20. The sole assembly of claim 19, wherein a medial side of the
upper plate is stiffer than a lateral side of the upper plate.
21. The sole assembly of claim 1, wherein the thickness of the
upper plate varies from a portion of a medial side to a portion of
a lateral side.
22. The sole assembly of claim 21, wherein the thickness of the
lower plate varies from a portion of a medial side to a portion of
a lateral side.
23. A shoe comprising: an upper portion; and a sole assembly
including, a heel cradle configured to cradle a heel of a human
foot when the human foot is rested within the heel cradle; an upper
plate including a first part connected to the heel cradle and a
second part located farther from the heel cradle than is the first
part; a lower plate including a first part which is connected to
the first part of the upper plate and including a second part which
is connected to the second part of the upper plate; an oblong gap
located between the upper plate and lower plate and between the
first and second parts of the upper and lower plates shaped such
that a gap dimension between the upper and lower plates in a first
direction, measured from the first part of the upper plate to the
second part of the upper plate, is greater than a gap dimension
between the upper and lower plates in a second direction which is
perpendicular to the first direction.
24. A sole assembly comprising: an outsole located on a side of the
sole assembly and configured to support the sole assembly; a
cushion material located next to the outsole, means for cradling a
heel of a human foot when the human foot is rested within the means
for cradling; and means for storing energy generated during walking
connected to the means for cradling.
25. A sole assembly comprising: an upper plate including a first
part and a second part and having a first stiffness; a lower plate
having a second stiffness greater than the first stiffness and
including a first part which is connected to the first part of the
upper plate and including a second part which is connected to the
second part of the upper plate, an oblong gap located between the
upper plate and lower plate and between the first and second parts
of the upper and lower plates shaped such that a gap dimension
between the upper and lower plates in a first direction, measured
from the first part of the upper plate to the second part of the
upper plate, is greater than a gap dimension between the upper and
lower plates in a second direction which is perpendicular to the
first direction.
26. The sole assembly of claim 25, wherein the upper plate and
lower plate are comprised of different materials.
27. The sole assembly of claim 26, wherein the upper plate
comprises TPU and the lower plate comprises carbon fiber.
28. The sole assembly of claim 26, wherein the upper plate
comprises TPU and the lower plate comprises poly-paraphenylene
terephthalamide.
29. The sole assembly of claim 26, wherein the upper plate has a
greater thickness in the vertical direction than the lower
plate.
30. The sole assembly of claim 29, wherein the thickness of the
upper plate is 3 mm and the thickness of the lower plate is 1.5
mm.
31. The sole assembly of claim 26, wherein the lower plate includes
an insert.
32. The sole assembly of claim 31, wherein the insert is disposed
on a medial side of the lower plate and comprises a material having
a different stiffness than material of the lower plate.
33. The sole assembly of claim 25, wherein the upper plate and
lower plate include wings projecting toward a toe region of the
sole assembly.
34. The sole assembly of claim 33, wherein a wing on a medial side
of the upper and lower plates is longer than a wing on a lateral
side.
35. The sole assembly of claim 25, wherein the lower plate includes
a cavity.
36. The sole assembly of claim 35, wherein the upper plate includes
a cavity at least partially overlapping the cavity of the lower
plate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a device that supports a
person's foot, and more specifically, to a shoe sole assembly
having a spring mechanism for storing and releasing mechanical
energy during the gait cycle.
[0003] 2. Discussion of the Background
[0004] Footwear has often incorporated various methods of absorbing
impact energy generated while a person walks or runs. Specifically,
sponges or cushion materials are often used to absorb and dissipate
energy throughout the wearer's gait cycle. However, in order to
achieve sufficient cushioning, a large amount of cushioning
material that substantially covers the entire plantar region of the
shoe may be necessary. This creates a thick and heavy sole
structure that adds weight to the shoe and prevents air flow to the
plantar region of the wearer's foot. Cushion material may also
become compacted over time and lose its cushioning effect, and does
very little to store energy for use during the gait cycle.
[0005] Shoe makers have also created "through-holes" in the cushion
material that extend from the lateral to medial sides of the shoe
sole in order to reduce the weight of the shoe. However, as these
conventional through-holes are typically mere vacancies created in
the cushion material, they do not provide effective air flow to the
plantar region of the wearer's foot. Moreover, conventional
through-holes do not provide a structure for effectively storing
mechanical energy.
[0006] Various spring elements have been used in footwear in an
attempt to store impact energy for use during the gait cycle. For
example, U.S. Pat. No. 6,449,878 discloses a spring assembly
including a first spring element that extends over a large area of
the shoe sole, and a second spring element attached to the first
element in a midfoot region but spaced from and opposing the first
element in a heel region of the shoe. The opposing first and second
spring elements form a tension spring in the heel region of the
shoe. However, this spring assembly is complex and requires large
and highly resilient components that are too heavy to be of
practical use for most shoes, particularly athletic shoes.
[0007] While simple and light-weight plastic-type assemblies have
been implemented into footwear, these structures have generally
been used to provide rigidity to certain regions of the sole and
cannot efficiently store and release energy during the gait cycle.
For example, U.S. Patent Publication 2003/0005600A1 discloses a
plastic shank member embedded in a midfoot region of a shoe sole.
The shank member is a substantially rigid sheet of material closed
to form an oblong cross sectional shape. Placement of the shank
member in the midfoot region of the midsole provides greater
rigidity to this area of the midsole so that the forefoot of the
midsole is more bendable. However, the shank is not disclosed as a
spring element for storing and releasing energy during gait.
[0008] Furthermore, the present inventors have recognized that when
any type of energy storage device is implemented in footwear, foot
placement within the shoe during contact with the ground is
important to realizing a spring effect. Moreover, if the foot is
improperly placed relative to the energy storage device, the device
may interfere with the natural sequence of pressure distribution of
the foot during the footstep, thus resulting in foot discomfort.
For example, in the heel area, the heel of the foot tends to break
contact or at least reduce pressure on the heel portion of the sole
of the shoe when the foot is lifted. Accordingly, the heel of the
foot may drift within the shoe and not impact the sole of the shoe
in the optimum location for cushion effect and energy storage.
Conventional shoes have not recognized this importance of heel
placement, and thus have not provided comfortable and efficient
energy storage mechanisms.
SUMMARY OF THE INVENTION
[0009] Accordingly, one object of the present invention is to
address at least some of the above described and/or other problems
of conventional footwear.
[0010] Another object of the present invention is to provide a
simple, light-weight footwear spring element for effectively
storing and releasing energy during the gait cycle.
[0011] Yet another object of the present invention is to provide a
footwear mechanism for effectively positioning the wearer's heel in
relation to a sole spring element in order to enhance efficient
storage of energy in the spring at impact. Any of these and/or
other objects can be provided by a sole assembly according to the
present invention.
[0012] According to one aspect of the present invention, a sole
assembly is disclosed including: a heel cradle configured to cradle
a heel of a human foot when the human foot is rested within the
heel cradle, a rigid upper plate including a first part connected
to the heel cradle and a second part located farther from the heel
cradle than is the first part, a lower plate including a first part
which is connected to the first part of the upper plate and
including a second part which is connected to the second part of
the upper plate, an oblong gap located between the upper plate and
lower plate and between the first and second parts of the upper and
lower plates shaped such that a gap dimension between the upper and
lower plates in a first direction, measured from the first part of
the upper plate to the second part of the upper plate, is greater
than a gap dimension between the upper and lower plates in a second
direction which is perpendicular to the first direction.
[0013] According to another aspect of the present invention, a shoe
is disclosed including: an upper portion; and a sole assembly
including, a heel cradle configured to cradle a heel of a human
foot when the human foot is rested within the heel cradle, a rigid
upper plate including a first part connected to the heel cradle and
a second part located farther from the heel cradle than is the
first part, a lower plate including a first part which is connected
to the first part of the upper plate and including a second part
which is connected to the second part of the upper plate, an oblong
gap located between the upper plate and lower plate and between the
first and second parts of the upper and lower plates shaped such
that a gap dimension between the upper and lower plates in a first
direction, measured from the first part of the upper plate to the
second part of the upper plate, is greater than a gap dimension
between the upper and lower plates in a second direction which is
perpendicular to the first direction.
[0014] According to another aspect of the invention, a sole
assembly is disclosed including: an outsole located on a side of
the sole assembly and configured to support the sole assembly, a
cushion material located next to the outsole, a means for cradling
a heel of a human foot when the human foot is rested within the
means for cradling, and a means for storing energy generated during
walking connected to the means for cradling.
[0015] According to another aspect of the invention, a sole
assembly is disclosed including: a rigid upper plate including a
first part and a second part and having a first stiffness, a lower
plate having a second stiffness greater than the first stiffness
and including a first part which is connected to the first part of
the upper plate and including a second part which is connected to
the second part of the upper plate, an oblong gap located between
the upper plate and lower plate and between the first and second
parts of the upper and lower plates shaped such that a gap
dimension between the upper and lower plates in a first direction,
measured from the first part of the upper plate to the second part
of the upper plate, is greater than a gap dimension between the
upper and lower plates in a second direction which is perpendicular
to the first direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0017] FIG. 1 is a perspective view of a shoe incorporating a sole
assembly and heel cradle according to one non-limiting embodiment
of the present invention;
[0018] FIG. 2 shows the medial side of a sole assembly according to
one exemplary embodiment of the present invention;
[0019] FIG. 3 shows the lateral side of a sole assembly according
to one exemplary embodiment of the present invention;
[0020] FIG. 4 shows the back of a sole assembly according to one
exemplary embodiment of the present invention;
[0021] FIG. 5 shows the bottom of a sole assembly including the
outsole and various cross-section lines according to one exemplary
embodiment of the present invention;
[0022] FIG. 6 shows the top of a sole assembly without the shoe
upper according to one exemplary embodiment;
[0023] FIG. 7 shows a cross-section along line 7 of the sole
assembly shown in FIG. 5;
[0024] FIG. 8 depicts a cross-section along line 8 of the sole
assembly shown in FIG. 5;
[0025] FIG. 9 depicts a cross-section along line 9 of the sole
assembly shown in FIG. 5;
[0026] FIG. 10 depicts a cross-section along line 10 of the sole
assembly shown in FIG. 5;
[0027] FIG. 11 depicts a cross-section along line 11 of the sole
assembly shown in FIG. 5;
[0028] FIG. 12 depicts a cross-section along line 12 of the sole
assembly shown in FIG. 5;
[0029] FIG. 13 shows a top view of a bottom plate according to one
exemplary embodiment of the present invention; and
[0030] FIG. 14 shows a perspective view of an upper plate and heel
cradle according to one exemplary embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Referring now to the drawings, wherein like reference
numerals designate identical or corresponding parts throughout the
several views, FIG. 1 is a perspective view of a shoe incorporating
a sole assembly according to one non-limiting embodiment of the
present invention. As seen in this figure, the shoe includes an
upper 1 attached to a sole assembly 2. The upper is preferably made
of durable sheets of non-elastic material such as leather, canvas,
synthetic material or any other upper material known to those
skilled in the art of shoes. In a preferred embodiment, the upper
is a breathable nylon mesh material reinforced with outer layer
regions of nylon netting. The upper 1 may be attached to the sole
assembly 2 by stitching, adhesion or any other method known in the
art.
[0032] In the embodiment of FIG. 1, the sole assembly 2 includes a
spring mechanism having an upper plate 3 and a lower plate 4 in
contact with one another to form a gap 11 through the sole assembly
2. Also included is a heel cradle structure 5, and rear and front
cushion materials 6 and 7 respectively. In the embodiment of FIG.
1, the rear cushion material 6 includes a through hole 9 that works
with the gap 11 to facilitate air flow to the bottom portion of the
sole assembly as will be further described below. An outsole 8 is
formed on a bottom portion of the cushion materials 6, 7 as will
also be discussed below.
[0033] FIG. 2 and 3 show a medial and lateral side respectively of
the sole assembly 2 shown in FIG. 1. As seen in these figures, the
upper plate 3 and a lower plate 4 are connected to one another so
as to form an oblong shaped gap 11 that extends as a hole from the
lateral to medial side of the sole assembly 2. The upper plate 3 is
concave facing downward and extends longitudinally from a heel
region to a metatarsal region of the sole assembly 2, while the
lower plate 4 is concave facing upward and connects to the upper
plate 3 at the heel and metatarsal regions respectively. However,
in alternative embodiments the upper and or lower plates may be
flat or concave in the opposite direction, and may be further
contoured to fit the shape of a human foot. Further the upper plate
3 and lower plate 4 may be attached by any of various methods, such
as, for example, by adhesive, heat bonding, ultrasonic welding or
mechanical connection etc.
[0034] In the embodiment of FIGS. 2 and 3, the gap 11 extends
approximately 10.5 cm longitudinally along the sole assembly 2, and
is approximately 1.2 cm high at a middle point of the gap, however
dimensions of the gap vary according to the size of the sole
assembly 2, and/or according to the spring effects desired. In one
embodiment, the gap is approximately 25-35% of the length of the
sole assembly 2. Preferably, the length of the gap (not considering
curvature) is from approximately 100 mm to 130 mm, and the height
is from approximately 5 mm to 14 mm.
[0035] In the embodiment of FIGS. 1-3, the upper plate 3 is more
flexible than the lower plate 4. Specifically, the upper plate 3
has a thickness of approximately 3 mm, and is formed with medial
and lateral sidewalls 3a and 3b that provide some rigidity to the
upper plate 3, while the lower plate 4 is approximately 1.5 mm
thick and generally planar along a transverse cross section.
However, the upper plate 3 is made of a relatively flexible
material such as thermoplastic polyurethane (TPU), while the bottom
plate is made of a stiffer material such as carbon fiber or
KEVLAR.RTM. (poly-paraphenylene terephthalamide) etc., which have a
higher tensile strength and flexural modulus. The present inventors
have discovered that the softer TPU used in the upper plate 3,
provides a cushioning effect while the more rigid carbon fiber
lower plate 4 provides excellent energy storage characteristics. In
alternative embodiments, the thickness, structural design and/or
the material composition of the plates may be varied to provide
upper and lower plates having the same or different stiffness
properties. Further the upper and/or lower plate can be designed to
have localized stiffness properties as will be further described
below.
[0036] One benefit of using carbon fiber in the plates, especially
the lower plate 4, is that because the carbon fiber is very strong
and stiff, the lower plate 4 can provide the desired spring effect
with a reduced thickness relative to other materials. Thus, the
vertical dimension of gap 11 is increased without increasing the
overall height of the sole assembly 2. This increase allows a
greater range of travel between the upper plate 3 and the lower
plate 4 within a given overall height of the sole assembly 2. In
other words, with one or both plates made of a high stiffness
material such as carbon fiber, the range of travel between the
plates can be maintained while the sole assembly can be made
shorter in height than would be possible with other materials.
[0037] In the embodiment of FIGS. 1-3, the heel cradle 5 is
integrally formed with the upper plate 3, and the lower plate 4
connects to a middle region of the heel cradle 5. Thus, a portion
of the upper plate 3 extends beyond the contact point with the
lower plate to form a cantilever portion 5a, which is contoured to
cup or cradle the wearer's heel. As seen by the dashed lines in
FIGS. 2 and 3, the rear cushion material 6 overlaps the bottom of
the cantilevered portion 5a in order to provide support for the
portion 5a The heel cradle 5 also includes a substantially flat and
flexible strip portion 5b that is in flush contact with an outer
surface of the upper 1 of the shoe to provide comfortable support
for the heel, while a more rigid portion 5c overlaps the strip 5b
and is made integral with the upper plate 4 to provide
reinforcement of the strip 5b.
[0038] As best seen in FIG. 4, the rear portion of the heel cradle
5 includes a rigid wall 5d that is integral with the cantilevered
part 5a and the reinforcing portion 5c. The wall 5d provides strong
support for the heel at impact during, for example, running. The
portions 5a, 5c and 5d of the heel cradle are preferably made of
the same material as the upper plate 3. The reinforcing portion 5c
(and strip 5b beneath it) extend from the rigid wall 5d along the
lateral and medial sidewalls of the upper 1, and are contoured to
approach the upper plate 3 as they run forward toward a midfoot
region of the sole assembly 2. Thus, side portions of the heel
cradle 5 include an opening 18, which can allow some air flow
through the upper 1 to the heel region of the shoe interior. In the
embodiment of FIGS. 1-4 and 14, the heel cradle 5 extends
approximately 3.7 cm up the sidewall of the upper 1 at a maximum,
and extends approximately 7 cm along the sidewalls from a rear of
the upper 1. It is to be understood, however, that the portion of
the heel cradle 5 overlapping the upper 1 can have varying
dimensions for different size shoes and for different shoe types,
as long as the overall heel cradle structure 5 supports the heel to
enhance centering of the wearer's heel during use.
[0039] The addition of the heel cradle 5 can enhance the effect of
the spring mechanism by improving a position of the wearer's heel
as the heel of the foot lifts and descends during walking or
running. The present inventors have realized that by consistently
centering the heel of the foot in relation to the sole assembled,
the upper plate 3 and lower plate 4 more efficiently store and
release energy during gait. Furthermore, proper positioning of the
heel allows the sole assembly 2 to smoothly accommodate the natural
gait of the wearer and to provide support where needed. To achieve
proper positioning of the heel of the foot, the heel cradle 5 is
typically added to the shoe on the outside of the upper 1 as shown
in FIGS. 1-4; however, the heel cradle 5 may be formed inside or as
an integral part of the heel region of the upper 1.
[0040] Further in the non-limiting embodiment shown in FIGS. 1-4
and 14, the heel cradle 5 is an integral part of the upper plate 3.
One benefit of this arrangement is that the heel cradle 5 not only
centers the heel of the foot on the upper plate 3, but flexes as
the upper plate 3 flexes. In another non-limiting embodiment, the
heel cradle 5 may be a separate component and attached to the upper
plate 3 via any of the various joining processes discussed above
regarding connecting the plate. Additionally, the heel cradle 5 may
be made of a different material than the upper plate 3.
Accordingly, the stiffness of the heel cradle 5 may be made
different from the plates by changing the material or by changing
the dimensions of the heel cradle 5.
[0041] As shown in FIG. 14, the heel cradle 5 may include openings
on the sides to provide ventilation to the heel region.
Additionally, in embodiments where the heel cradle 5 is external to
the upper 1, the heel cradle may provide an aesthetically pleasing
design. In the embodiment shown in FIGS. 4 and 14, the area between
the openings 18 and above rigid wall 5d is slightly lower in height
than the area above openings 18. This enhances the fit of the heel
cradle 5 to the Achilles tendon area of the heel.
[0042] As seen in FIGS. 1-4, the rear cushion 6 supports the upper
plate 3 and heel cradle 5 in the heel area, and supports the lower
plate 4 from the heel to approximately midfoot, while front cushion
7 supports the forefoot. Cushion material 6,7 is preferably made of
a resilient, shock-absorbing material such as, for example,
ethylene vinyl acetate (EVA). Rear cushion gap 9 is provided to
support the cantilevered portion of the upper plate 3 and heel
cradle 5. The presence of the rear cushion gap 9 may improve the
flexibility of the heel of the shoe while decreasing the weight of
the shoe and improving air flow directly around the heel of the
foot as will be further described below. In some non-limiting
embodiments, the rear cushion gap 9 may not be present, may be
shaped differently than as shown in FIG. 4, or may include multiple
smaller gaps.
[0043] The rear cushion 6 is coupled to the front cushion material
7 to provide a planar surface for attaching the outsole 8. The
outsole 8 is preferably implemented as a layer of deformable rubber
material that contacts the ground when the shoe is in use, and
preferably includes treads that are designed to grip a variety of
ground surfaces. As seen in FIGS. 2-4 the outsole 8 is shown as
curved along a contour provided by the sole assembly 2. Such
contouring accommodates a natural human gait by providing a smooth
flow from heel to toe as the foot twists during walking or running.
Details of the outsole 8 are discussed below.
[0044] The present inventors have discovered that the sole assembly
of the exemplary embodiment of FIGS. 1-4 provides a simple and
light-weight footwear spring element for effectively storing and
releasing energy during the gait cycle. Further the heel cradle can
effectively position the wearer's heel in relation to the sole
spring element in order to enhance efficient storage of energy in
the spring at impact. It is to be understood, however, that the
spring mechanism may be used to provide improved spring
characteristics without the need for the heel cradle, and the heel
cradle can enhance the energy storage and release characteristics
of springs other than that shown in FIGS. 1-4. Still further use of
the absorbing material 6, 7 can absorb and dissipate impact shock
during heel strike, and operate to dampen the spring effect of the
spring mechanism of the sole assembly 2.
[0045] Specifically, prior to heel impact of the gait cycle when
the heel is not in contact with the ground, the heel cradle 5 can
provide lateral support for the heel and maintain a substantially
center position of the heel on the sole assembly 2. A downward
force created from heel contact to the midstance portion of the
gait cycle is applied to the upper plate 3. This causes the upper
plate 3 to deflect in elastic deformation downward toward the lower
plate 4, thus storing the energy of the applied load. This stored
energy is then released during the windlass phase of the gait cycle
when the foot locks into place and moves from midstance to toe off.
This creates a natural propulsion sensation to the wearer. The
absorbing material functions to absorb and disperse shock forces in
order to cushion the foot during this gait cycle, and can further
dampen the spring effect of the spring element to provide a
smoother feel.
[0046] FIG. 5 shows a bottom surface of a sole assemble in
accordance with an embodiment of the present invention. As seen in
this figure, cross-section lines 7-12 are shown to define the
cross-section planes of FIGS. 7-12 respectively. As also seen in
FIG. 5, the outsole 8 is substantially continuous from the rear to
the front of the sole assembly 2. However, in other embodiments,
the outsole could be two or more separate parts, e.g., a rear part
and a front part separated by a gap or flexion area The outsole 8
includes a tread portion (designated by number 8), which can be
made of various tough, flexible materials such as, for example,
carbon rubber, and is designed to provide gripping of various
surfaces. In the embodiment of FIG. 5, the tread portion 8 is
implemented as a substantially planar sheet of rubber having
serpentine raised edges and grooves that extend in a longitudinal
direction.
[0047] The tread portion 8 includes a plurality of small holes 8a
therein at a forefoot region of the sole assembly, and a larger
hole 8d extending from the heel to midfoot region of the sole
assembly 2. In the embodiment of FIG. 5, the tread holes 8a
correspond to holes 8b in the absorbing material 7 to provide front
ventilation holes 8c in the bottom of the shoe to permit air flow
to the forefoot interior of the shoe. Similarly, the hole 8d
corresponds to hole 8e provided in the rear cushion 6, hole 8f
provided in lower plate 4 and hole 8g provided in upper plate 3,
such that a heel ventilation hole 12 allows air flow to an interior
of the shoe. Although the holes are shown in FIGS. 5 and 6 as
having a teardrop shape, other shapes are possible. Additionally,
not all of the upper plate 3, lower plate 4, or rear cushion 6 need
to have similarly shaped holes. Furthermore, as shown in FIG. 14,
the holes may have a mesh or reinforcing structure added.
[0048] FIG. 6 shows a top surface of the sole assembly 2 at the
interior of the shoe. As seen in this figure, the sole assembly 2
includes an outsole 8 having a front cushion 6 provided at a
forefoot region thereof, and a rear cushion 7, lower plate 4 and
upper plate 3 sequentially stacked on a heel to mid-foot region of
the outsole 8. As also seen in FIG. 6, the ventilation holes 8b and
12 extend to the interior of the shoe. The ventilation holes 8c and
12 preferably include a screen or mesh material that permits air
flow into the shoe while keeping debris from entering the interior
of the shoe. Thus, the sole assembly of FIGS. 5 and 6, is designed
to permit substantial air flow from an exterior of the shoe to a
plantar region of the wearer's foot. This is further enhanced by
the cushion gap 9 in the absorbing material 6 and the gap 11 in the
spring mechanism, which allow free flow of air around the heel
portion of the shoe and to the ventilation hole 12. Further
ventilation holes 8a and 12 reduce the weight of the sole assembly,
while enhancing the performance characteristics of the shoe by
guiding the heel to center strike upon impact.
[0049] FIGS. 7-12 show various cross sections of the sole assembly
of FIGS. 1-6 in accordance with one embodiment. FIG. 7 shows a
longitudinal cross section of the sole assembly of FIG. 5. As seen
in FIG. 7, the upper plate 3 is formed of TPU depicted by a
diagonal cross sectional marking, while the lower plate 4 is formed
from carbon fiber depicted by a vertical-horizontal cross sectional
marking. Areas 14 and 15 show a contact region of the upper and
lower plate at a heel and mid-foot region respectively. Further,
the upper and lower plates include a break at this cross section
due to the hole 8g in the upper plate 3 and the hole 8f in the
lower plate 4. As also seen in this figure, the absorbing material
7 at the metatarsal region of the forefoot includes a cavity having
a second absorbing or cushioning material 20 provided therein. In
one non-limiting embodiment, cushioning material 7 and 20
preferably have different durometer hardness ratings. However, in a
preferred embodiment, the cushioning material 7 and 20 are
comprised of the same material.
[0050] FIG. 8 shows a cross-section of the outsole 8 taken along
the section-line as defined in FIG. 5. As shown in FIG. 8, the
first foam material 20 provides a cushion across the metatarsal
region of the foot. Below the first foam material 20 is forefoot
absorbing material 7 and the outsole 8. In one non-limiting
embodiment, the upper plate 3 and lower plate 4 do not extend to
the cross-section shown in FIG. 8. By not placing the plates in the
region of this cross-section, natural flexure at the ball of the
foot occurs independently of the upper plate 3 and lower plate 4.
In another non-limiting embodiment, the upper plate 3 and lower
plate 4 are formed such that they are present in the metatarsal
region, but are structured to allow flexure at the ball of the foot
as needed. It should be noted that the upper plate 3 and lower
plate 4 may be made longer or shorter depending on the particular
needs of the wearer. In some cases, the plates may be made shorter
and moved closer to the heel of the sole assembly 2. In other
cases, the plates may be moved forward, either by lengthening the
plates relative to the length of the sole assembly 2 or by moving
the plates themselves forward.
[0051] FIG. 9 shows a cross-section of the outsole 8 taken at the
section-line as defined in FIG. 5. In this view, the first foam
material 20, absorbing material 7, and outsole 8 are present as
shown in FIG. 8. However, as section-line of FIG. 9 is closer to
the middle of the outsole 8 than section-line of FIG. 8, upper
plate 3 and lower plate 4 are shown on the right and left sides of
the outsole 8. In this non-limiting embodiment, the upper plate 3
and lower plate 4 are Y-shaped or have extended parts on their
right and left edges as shown in exemplary FIGS. 13 and 14, which
will be discussed further below. Thus, in the cross-section
depicted in FIG. 9, only the extended parts appear. The upper plate
3 and lower plate 4 plate make contact in the region of
section-line of FIG. 9. As discussed above, the plates may be
attached through various methods, including mechanical
attachment.
[0052] As also by a comparison of FIGS. 8 and 9, the sole assembly
2, upper plate 3 and lower plate 4 are thinner towards a center of
the shoe. Alternatively, the upper plate 3 and lower plate 4 may
have uniform widths as measured horizontally across the shoe. When
the widths and thicknesses of the plates are uniform, the plates
may easily be formed by simple extrusion. However, in order to
enhance response of the plates as a foot travels from heel to toe
during a footstep, the plates typically have a varying width (and
possibly thickness as discussed below) along their length. In
addition to altering the performance of the plates during
deflection, such curvature allows the plates to fit beneath the
contours of the foot and enhances aesthetic appeal.
[0053] FIG. 10 shows a cross-section taken at the line as defined
in FIG. 5. In this non-limiting embodiment, the upper plate 3 is
shown as having a concave shape pointing upward to form sidewalls
3a and 3b which can prevent the foot from slipping from side to
side. A comparison of FIGS. 9 and 10 shows that the upper plate 3
and lower plate 4 have separated and have formed the beginning
areas of the gap 11. Additionally, foam material 6 is shown, which
makes up the rear cushion 6 shown in FIGS. 1-4.
[0054] FIG. 11 shows a cross-section taken at the section-line as
shown in FIG. 5. As this section-line is further back from the
front of the shoe than is section-line of FIG. 10, the vertical
dimension of gap 11 is larger. Additionally, the concavity of the
upper plate 3 has decreased. Finally, FIG. 12 shows a cross-section
taken at the section-line as shown in FIG. 5. Although other
locations are possible, an optional rear cushion cavity 9 is shown
in approximately the center of the shoe. The presence of the rear
cushion cavity 9 allows more flexion in the center of the upper
plate 3, especially if the upper plate cavity 12 and lower plate
cavity 10 are present, and permits air flow as previously
described.
[0055] Further shown in FIG. 12 are the vertical protrusions 19
present on the upper plate 3. In this embodiment, the vertical
protrusions 19 are the remnants of the concave-upward parts of the
upper plate 3. However, the vertical protrusions may be formed
separately from the concave-upward parts of the upper plate 3. In
fact, it is not necessary for any other part of the upper plate 3
to be concave upward in order for the upper plate 3 to include the
vertical protrusions 19.
[0056] The sole assembly of FIGS. 1-12 has been described as having
a neutrally-positioned plate that generally allows for the
high-arched, rigid foot-type to apply consistent pressure through
the gait cycle and receive the maximum cushioning and spring
effect. In this embodiment, the material and thickness of each of
the upper plate 3 and lower plate 4 is substantially constant and
symmetrical across a respective plate to provide little variation
in stiffness properties across a respective plate. However,
alternative embodiments may be implemented to accommodate different
foot types. For example, an asymmetric design to give greater
support on the medial (inside) portion of the shoe to better
support a medium-arched semi-flexible foot as it pronates inward.
Similarly, maximum support on the medial side of the shoe may be
needed to support an extremely flexible and low-arched foot type.
The medial side material would need to be very stiff and noticeably
less flexible, as the general body-type for this kind of foot-type
is much larger, thus exerting more pressure on the spring device.
The stiffness would eliminate the potential for collapse in the
midfoot.
[0057] Such asymmetrical levels of stiffness can reduce foot
pronation. For example, human feet naturally rotate or roll inward
during walking, i.e., the feet pronate. Over-pronation occurs when
the arch of a human foot collapses upon weight bearing. Problems
associated with over-pronation include soft-tissue inflammation and
joint stress. To avoid over-pronation, shoes with augmented arch
supports have been designed. However, the augmentation may
undesirably add to the overall weight and height of the shoe.
Additionally, as the augmentation is typically designed merely to
prevent collapse of the arch of the foot, the augmentation does not
efficiently store energy during walking or running. Thus, rather
than augmenting the arch of a shoe with thicker padding which in
turn would increase the weight and height of the shoe, a particular
part of the foot such as, for example, the arch area of the foot,
may be preferentially supported by altering the stiffness
characteristics of the plates, either by changing plate geometry or
by changing materials.
[0058] FIG. 13 shows a general shape of the upper plate 3 and lower
plate 4 in accordance with an embodiment of the present invention.
As seen in this figure, the plate 40 includes front wings 42 and a
through hole 44, which generally divide the plate 40 into a medial
side 46 and lateral side 48 having a boundary indicated by the
vertical dashed lines in the figure. In one non-limiting
embodiment, a portion or all of the medial side 46 of the plate 40
may be made of stiffer material than a portion of the lateral side
48. For example, part of the medial side of the plate may be
fabricated from carbon fiber or other material while the remainder
of the plate may be made of relatively more flexible TPU. In one
non-limiting embodiment, the carbon fiber may comprise one or more
separate inserts 24 attached or placed inside the plate as shown in
FIG. 13. The insert 24 may be replaceable to enable one to
customize the shoe for a particular wearer or use. Provisional
Application Ser. No. 60/709792 discloses various methods of
measuring a characteristic of the wearer in order to determine a
footwear component such as insert 24 suitable for the wearer. This
provisional application is hereby incorporated herein in its
entirety. In another non-limiting embodiment, the inserts may be
integrally formed into the plate during the manufacture of the
plate.
[0059] Various methods of stiffening particular portions of the
plates exist. If the stiffness of the plate depends largely on the
number of fibers present in the material, such as it typically does
with fiber-glass or carbon fiber materials, the density of the
fibers in a part of the plate may be increased or reduced during
manufacture to affect the stiffness in a particular area. In yet
another non-limiting embodiment, the chemical composition of the
plate may be altered in various parts such that the stiffness
changes.
[0060] Further, the thickness of the plate 40 may be increased on
the medial side 46. As the stiffness of a cross-section of a plate
is proportional to the cube of the thickness of the plate, even a
small change in the thickness of the plate will have a large affect
on the overall stiffness of the plate. Thus, grooves, ribs, and
plates with gradually varying thicknesses may be used to affect the
localized stiffness of the upper plate 3 or lower plate 4 or both.
Still further, the medial side may be asymmetrical in shape as
shown by the phantom wing extension 50 on the medial side, which
may stiffen this area.
[0061] As shown in FIG. 13 wings 42 are typically positioned on the
medial and lateral sides of the plate 40. In FIG. 14, the wings 42
are shown on the upper plate 3 as slightly tapered protrusions
extending toward the toe area. Thus, the wings 42 enhance stability
of the sole assembly 2 by stiffening the outer portions of the sole
assembly, but add less weight than would a shape in which the area
between the wings 42 is filled with material. Accordingly, the
stiffness of the metatarsal region can be enhanced with little
added material. Wings 42 added to the lower plate 4 achieve similar
results. Additionally, the tapering shape of the wings 42 in the
vertical direction provides enhanced ability to attach the lower
plate 4 and upper plate 3 to the rest of the sole assembly 2, i.e.,
the taper provides a fillet shape in the connection area.
[0062] In addition to asymmetry of the upper and lower plates
themselves, the spring assembly may be positioned differently
within the sole assembly to accommodate different foot types. For
example, moving the spring mechanism forward or back may change a
performance characteristic of the sole assembly. For example, a
smaller system that is closer to the heel may work better for a
mild overpronator. As another example, moving the system forward
may create the best forefoot cushioning in a shoe. Still further,
material and design variations may be implemented to provide a
lower midsole height.
[0063] Clearly, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *