U.S. patent application number 09/887523 was filed with the patent office on 2002-12-26 for footwear with bladder filter.
Invention is credited to Dojan, Fred, Hazenberg, K. Peter, Passke, Joel L., Swigart, John F..
Application Number | 20020194747 09/887523 |
Document ID | / |
Family ID | 25391334 |
Filed Date | 2002-12-26 |
United States Patent
Application |
20020194747 |
Kind Code |
A1 |
Passke, Joel L. ; et
al. |
December 26, 2002 |
Footwear with bladder filter
Abstract
An article of athletic footwear having an air-filled bladder
disposed in a sole structure is disclosed. The air-filled bladder
is in fluid communication with ambient air through a filter that
permits ambient air to enter the bladder but restricts liquids and
particulates from entering the bladder. In operation, the filter
and bladder may be portions of a bladder system that absorb shock
when the footwear contacts a playing surface. Alternatively, the
filter and bladder may be portions of a bladder system that
ventilates the interior of the footwear. The filter may be formed
of expanded polytetrafluoroethylene that is attached to a
carrier.
Inventors: |
Passke, Joel L.; (Hillsboro,
OR) ; Dojan, Fred; (Vancouver, WA) ;
Hazenberg, K. Peter; (Portland, OR) ; Swigart, John
F.; (Portland, OR) |
Correspondence
Address: |
BANNER & WITCOFF
1001 G STREET N W
SUITE 1100
WASHINGTON
DC
20001
US
|
Family ID: |
25391334 |
Appl. No.: |
09/887523 |
Filed: |
June 21, 2001 |
Current U.S.
Class: |
36/29 |
Current CPC
Class: |
A43B 13/206 20130101;
A43B 7/125 20130101; A43B 13/203 20130101; A43B 7/081 20130101 |
Class at
Publication: |
36/29 |
International
Class: |
A43B 013/20 |
Claims
That which is claimed is:
1. An article of footwear for receiving a foot of a wearer, said
article of footwear comprising: an upper for covering at least a
portion of the wearer's foot; a sole structure attached to said
upper; an air-filled bladder in fluid communication with ambient
air and attached to said article of footwear; and a filter in fluid
communication with said bladder and ambient air, said filter being
structured to permit ambient air to enter said bladder and restrict
liquids and particulates from entering said bladder.
2. The article of footwear of claim 1, wherein said filter includes
polytetrafluoroethylene.
3. The article of footwear of claim 2, wherein said
polytetrafluoroethylene is expanded polytetrafluoroethylene.
4. The article of footwear of claim 1, wherein said filter includes
one of the group consisting of high density polyethylene, ultrahigh
molecular weight polyethylene, polyvinylidene fluoride,
polypropylene, and ceramic filter materials.
5. The article of footwear of claim 1, wherein said filter is
hydrophobic and oleophobic.
6. The article of footwear of claim 1, wherein a perforated layer
is located over said filter, said perforated layer permitting air
to access said filter.
7. The article of footwear of claim 6, wherein said perforated
layer prevents large particles and objects from contacting said
filter.
8. The article of footwear of claim 1, wherein said bladder is
located in said sole structure.
9. An article of footwear for receiving a foot of a wearer, said
article of footwear comprising: an upper for covering at least a
portion of the wearer's foot; a sole structure attached to said
upper; an air-filled bladder in fluid communication with ambient
air and attached to said article of footwear; and a
polytetrafluoroethylene filter in fluid communication with said
bladder and ambient air, said filter being structured to permit
ambient air to enter said bladder and restrict liquids and
particulates from entering said bladder.
10. The article of footwear of claim 9, wherein said
polytetrafluoroethylene is expanded polytetrafluoroethylene.
11. The article of footwear of claim 9, wherein said filter is
hydrophobic and oleophobic.
12. The article of footwear of claim 9, wherein a perforated layer
is located over said filter, said perforated layer permitting air
to access said filter.
13. The article of footwear of claim 12, wherein said perforated
layer prevents large particles and objects from contacting said
filter.
14. The article of footwear of claim 9, wherein said bladder is
located in said sole structure.
15. The article of footwear of claim 14, wherein said filter is
located in said sole structure.
16. The article of footwear of claim 14, wherein said filter is
located in said upper.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to footwear. More
particularly, the present invention relates to a filter system that
prevents water, other liquids, and particulates from obstructing
the operation of components located within an article of
footwear.
[0003] 2. Description of Background Art
[0004] The principal objectives of modern athletic footwear design
are to minimize weight while maximizing comfort, cushioning,
stability, and durability. In order to meet this goal, footwear
designers use a broad range of materials, shoe design techniques,
and shoe-making methods. The basic design of athletic footwear,
however, remains largely uniform.
[0005] Typical athletic footwear includes two primary elements, an
upper and a sole. Usually formed of leather, synthetic materials,
or a combination thereof, the purpose of the upper is to
comfortably secure the wearer's foot to the sole while providing
necessary ventilation. Attached to the upper is the sole. The sole
ordinarily has a multi-layer construction which includes an insole,
midsole, and outsole. The insole commonly consists of a thin padded
member placed within the upper to enhance shoe comfort. The midsole
forms the middle layer of the sole and typically includes a
resilient foam material that cushions the foot from the impact
forces of running, walking, or other movement. The outsole is
usually formed of a durable material, such as synthetic or natural
rubber, to resist wear during use. In many cases, the outsole
incorporates a textured surface to enhance traction.
[0006] An alternate midsole construction, disclosed in U.S. Pat.
No. 4,183,156 (patented Jan. 15, 1980 to Marion F. Rudy),
incorporated by reference, includes a midsole component in which
cushioning is provided by a fluid-filled bladder formed of
elastomeric materials. The bladder includes a plurality of tubular
chambers which extend longitudinally through the length of an
article of footwear. The various tubular chambers are in fluid
communication and jointly extend across the width of the footwear.
U.S. Pat. No. 4,219,945 (patented Sep. 2, 1980 to Marion F. Rudy),
incorporated by reference, discloses a fluid-filled bladder
encapsulated within a foam material. The combination of the bladder
and the encapsulating foam material functions as a midsole. An
upper may be cemented to the upper surface of the encapsulating
foam material and an outsole may be affixed to the lower
surface.
[0007] The fluid-filled bladders disclosed in the '156 and '945
patents utilize a gas with a large molecular size that cannot
diffuse through the bladder walls. In contrast, other bladder
devices, including the bladders disclosed in U.S. Pat. No.
4,912,861 (patented Apr. 3, 1990 to Ing-Chung Huang); U.S. Pat. No.
5,335,382 (patented Aug. 9, 1994 to Yin-Jun Huang); and U.S. Pat.
No. 5,937,462 (patented Aug. 17, 1999 to Ing-Chung Huang), which
are incorporated by reference, use ambient air as the inflation
gas. Unlike a gas with a large molecular size, air diffuses through
bladder walls. Accordingly, those bladders that use air as an
inflation gas frequently include pumps or other inflation devices
to inflate the bladder with air. In addition, such bladders include
valves that prevent the air from escaping through the inlet.
[0008] Over time, water and a variety of particulates, including
dust, dirt, small rocks, plants, cleaning solutions, oils,
cosmetics, and paint, may enter bladders, pumps, and valves in
systems that include ambient air inlets. The bladders, pumps, and
valves may, therefore, develop particulate deposits or mold growths
that detrimentally affect performance of the bladder pumping system
or the valves that prevent air from escaping. Accordingly, the art
requires an improved ambient air-filled bladder that prevents
substantial amounts of liquids and particulates from entering the
bladder and detrimentally affecting bladder performance.
BRIEF SUMMARY OF THE INVENTION
[0009] The present invention relates to an article of footwear for
receiving a foot of a wearer. The article of footwear includes an
upper for covering at least a portion of the wearer's foot, a sole
structure attached to the upper, and an air-filled bladder in fluid
communication with ambient air and attached to the article of
footwear. In addition, the footwear includes a filter in fluid
communication with the bladder and ambient air, the filter being
structured to permit ambient air to enter the bladder and restrict
liquids and particulates from entering the bladder.
[0010] In one embodiment, the filter is located on the outer
surface of the footwear and a bladder is located in the sole
structure. As the wearer walks or runs, air passes through the
filter and the bladder is inflated. The purpose of the filter is to
prevent liquids and particulates from entering the system, thereby
adversely affecting the aesthetic properties of the footwear and
the mechanical properties of the bladder and other components. For
example, dust and water may collect in portions of the bladder that
are visible, thereby detracting from the aesthetic properties of
the footwear. Furthermore, deposits of liquids and particulates may
prevent components of the invention from functioning properly.
[0011] A variety of materials may be used for the filter, including
polytetrafluoroethylene, expanded polytetrafluoroethylene, high
density polyethylene, ultrahigh molecular weight polyethylene,
polyvinylidene fluoride, polypropylene, and ceramic filter
materials. In order to assist in preventing water and other liquids
from entering the system, the filter may be both hydrophobic and
oleophobic. A perforated layer of material may be placed over
exterior portions of the filter to protect and support the
filter.
[0012] Various advantages and features of novelty which
characterize the invention are pointed out with particularity in
the claims. However, for a better understanding of the invention,
its advantages, and objects obtained by its use, reference should
be made to the drawings, and to the accompanying descriptive
matter, in which there is illustrated and described preferred
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a side view of an article of footwear having a
bladder system according to a first embodiment of the present
invention.
[0014] FIG. 2 is a cross-sectional view of the article of footwear
depicted in FIG. 1.
[0015] FIG. 3 is a schematic view of the bladder system according
to the first embodiment of the present invention.
[0016] FIG. 4 is a schematic view of a bladder system according to
a variation of the first embodiment of the present invention.
[0017] FIG. 5A is a plan view of a filter structure according to
the first embodiment of the present invention.
[0018] FIG. 5B is a cross-sectional view of the filter structure
depicted in FIG. 5A.
[0019] FIG. 5C is a schematic plan view of a bladder used in the
first embodiment of the present invention.
[0020] FIG. 6 is a cross-sectional view of an article of footwear
having a bladder system according to a second embodiment of the
present invention.
[0021] FIG. 7 is a cross-sectional view of an article of footwear
having a bladder system according to a third embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Referring to the drawings, wherein like numerals indicate
like elements, an article of footwear in accordance with the
present invention is disclosed. The figures illustrate only the
article of footwear intended for use on the right foot of a wearer.
One skilled in the art will recognize that a left article of
footwear, such article being the mirror image of the right, is
included within the scope of the present invention.
[0023] As depicted in FIG. 1, footwear 100 is an article of
athletic footwear, particularly a running shoe. Footwear 100 may,
however, be any style of footwear, including a cross-training shoe,
tennis shoe, basketball shoe, walking shoe, in-line skate, ski
boot, hiking boot, work boot, sandal, dress shoe, or loafer.
Footwear 100 includes an upper 110 attached to a sole structure
120. The configuration of upper 110 and sole structure 120 may vary
in accordance with the style of footwear, but should permit the
incorporation of other components, as described below.
[0024] Sole structure 120, as depicted in FIGS. 1 and 2, includes
an insole 121, a midsole 122, and an outsole 123. Insole 121 is a
thin, shock-absorbing member located within upper 110 and beneath a
foot of a wearer that functions to enhance the comfort of footwear
100. Midsole 122 is attached to the lower surface of upper 110 and
may be formed of a foam material, such as polyurethane, phylon, or
ethylene vinyl acetate, that absorbs impact forces when footwear
100 contacts a playing surface. Outsole 123 is attached to the
lower surface of midsole 122 and may be formed of a durable,
wear-resistant polymer, such as carbon-black rubber compound. The
lower surface of outsole 123 may be textured to provide enhanced
traction when contacting the playing surface. In certain articles
of footwear, one or both of the insole and outsole layers may be
removed. When both the insole and outsole layers are removed, a
single layer of material functions as the entire sole structure.
Alternatively, sole structure 120 may have a configuration that
does not include a foam material.
[0025] In addition to upper 110 and sole structure 120, footwear
100 includes a plurality of components that may be arranged in a
plurality of configurations. In a first embodiment, described in
detail below, the components combine to form a system having an
ambient air-filled bladder that provides enhanced shock-absorbing
properties to footwear 100. In a second embodiment, an alternate
method of providing enhanced shock-absorbing properties is
disclosed. In a third embodiment, also described below, the
components combine to form a system that ventilates a foot received
within upper 110.
[0026] With regard to the first embodiment, depicted in FIGS. 2 and
3, footwear 100 also includes a filter structure 130 that permits
air to enter a first conduit 140 but restricts the entry of liquids
and particulates. Conduit 140, which may include a first valve 150,
places filter structure 130 in fluid communication with a pump 160.
A second conduit 170, which may include a second valve 180, places
pump 160 in fluid communication with a bladder 190. Accordingly,
air may pass through filter structure 130 and, through the action
of the various components, enter bladder 190.
[0027] The purpose of the various components of the first
embodiment are to inflate bladder 190 with air, thereby providing
midsole 122 with enhanced shock-absorbing properties. When worn by
an individual, during running for example, footwear 100
repetitively contacts the playing surface and, following each
contact, disengages from the playing surface. When in contact with
the playing surface pump 160 is compressed by the weight of the
wearer. As footwear 100 disengages from the playing surface, pump
160 returns to an uncompressed configuration, thereby decreasing
the pressure within pump 160 below the atmospheric pressure. The
pressure differential between pump 160 and the atmosphere draws air
through filter structure 130 and into first conduit 140. The air
then passes through first valve 150 and enters pump 160, thereby
equalizing the pressure between pump 160 and the atmosphere. When
outsole 123 again makes contact with the playing surface, the force
of the wearer's body compresses pump 160 and increases the pressure
of the air in pump 160. Due to the increased pressure, air is
forced into second conduit 170, passes through second valve 180,
and enters bladder 190. Note that first valve 150 permits air to
pass from first conduit 140 into pump 160, but prevents air from
exiting in the opposite direction. Similarly, second valve 180
permits the passage of air into bladder 190, but prevents the
passage of air in the opposite direction. In this manner, bladder
190 is placed in fluid communication with ambient air through
filter structure 130, which is also in fluid communication with
ambient air.
[0028] As noted above, pump 160 returns to an uncompressed
configuration when footwear 100 disengages from the playing
surface. When incorporated into midsole 122, the expansion of
midsole 122 following compression may provide a means that is
sufficient to return pump 160 to an uncompressed configuration.
Further means, however, may be necessary in situations where
midsole 122 is not sufficient to return pump 160 to an uncompressed
configuration or where pump 160 is not located in a midsole. The
further means may include a spring or element of foam that is
positioned within pump 160. In addition, the further means may rely
upon the inherent tendency of pump 160 to return to the
uncompressed state.
[0029] Other configurations, which use similar components may be
used without departing from the scope of the present invention. For
example, first valve 150 may be located adjacent to pump 160 or
inside pump 160. In another alternate configuration, a third
conduit 141 may be added such that air must pass through third
conduit 141 before passing through filter structure 130, as
depicted in FIG. 4. Moreover, multiple pumps 160 and bladders 190
may be disposed within footwear 100.
[0030] Filter structure 130 prevents water, other liquids, and a
variety of particulates from hindering the operation of various
system components, such as first valve 150, pump 160, and second
valve 180, and bladder 190. If permitted to enter the system,
particulates, for example, could collect around first valve 150
such that air is permitted to freely return from pump 160 to filter
structure 130, thereby escaping to the atmosphere and decreasing
the resulting pressure in bladder 190. In addition, water and
particulates could collect in bladder 190 and become visible from
the exterior of footwear 100, thereby decreasing the aesthetic
properties of footwear 100. If water were permitted to enter
bladder 190 or other portions of the system, the weight of footwear
100 may be increased significantly. Furthermore, particulates may
act as an abrasive that wears away portion of the system, thereby
decreasing durability. Accordingly, filter structure 130 acts to
prevent the entry of liquids and particulates that may have a
detrimental effect upon the system.
[0031] With reference to FIGS. 5A and 5B, filter structure 130
includes a first sheet 131, a second sheet 132, an intermediate
sheet 133, and a filter 134. In general filter 134 is a semi-porous
medium through which air must pass in order to enter first conduit
140 and, thereafter, bladder 190. First sheet 131 and intermediate
sheet 133 are located on opposite sides of filter 134 and provide
support and protection to filter 134. Perforations 135a in first
sheet 131 and perforations 135b in intermediate sheet 133 permit
air to pass through filter 134 and enter a recess 136 which is in
fluid communication with first conduit 140. Second sheet 132, in
combination with intermediate sheet 133, forms recess 136.
Alternate filter structure configurations may also be used without
departing from the scope of the present invention. For example,
intermediate sheet 133 may be absent from filter structure 130. In
addition, first conduit 140 could include a flared end to which
filter 134 may be attached, thereby abrogating the need for first
sheet 131, second sheet 132, and intermediate sheet 133.
[0032] In order to provide protection to filter 134 and permit
filter 134 to have a sufficient surface area, first sheet 131 and
intermediate sheet 133 may be bonded to the perimeter of filter
134. This configuration permits air to pass through perforations
135a in first sheet 131, pass between first sheet 131 and filter
134, and then pass through filter 134 and perforations 135b,
thereby increasing the effective area of filter 134 beyond that
which is directly exposed by perforations 135a. Filter 134 may also
have a corrugated configuration so as to facilitate air flow to all
portions of filter 134 and effectively increase the surface area of
filter 134.
[0033] Perforations 135 may be a plurality of small holes or a
lesser number of large holes in first sheet 131 and intermediate
sheet 133. To ensure that air passes freely through at least a
portion of filter 134, perforations 135a may be aligned with
perforations 135b. In addition to providing a means for air to
contact filter 134, perforations 135a may also act as a coarse
filter to prevent larger objects and particulates from contacting,
and thereby damaging, filter 134. A screen, which may be formed of
a porous material, a fabric, or a foam, may be attached to the
exterior of filter structure 130 if filter 134 requires additional
protection.
[0034] The materials from which filter 134 may be formed should
conform to general concepts that relate to air flow rate, water
entry pressure, particulate size, and operating temperature. With
regard to air flow rate, filter 134 should permit air to flow at a
rate that sufficiently inflates pump 160 between successive strides
of the wearer. That is, filter 134 should exhibit a minimum air
flow rate that permits pump 160 to expand from a state of complete
compression by drawing air through filter 134 during each discrete
time interval in which pump 160 is not compressed. For example, the
time interval may be when the wearer's foot is not in contact with
a playing surface during a single stride of the wearer. As such,
the variables upon which the minimum air flow rate depend are the
time between successive strides of the wearer and the volume of
pump 160. Any filter material that permits the passage of air may
be configured to exhibit the minimum air flow rate given a
sufficiently large filter area. For example, a substantial portion
of the exterior of upper 110 could be comprised of a filter
material that is in fluid communication with bladder 190. An
exemplary, practical filter area, however, would be within the
range of 0.1 and 1 square inches. As one skilled in the art will
recognize, particulate deposits or the presence of liquids on the
exterior of filter 134 may inhibit air flow. Accordingly, the
considerations discussed above should be adjusted to account for
decreased air flow due to the presence of foreign materials.
[0035] In addition to a minimum air flow rate, filter 134 should be
selected to have a minimum water entry pressure that prevents the
passage of water at a pressure differential equal to the vacuum
pressure created by the expansion of pump 160. As pump 160 expands,
a vacuum is created within pump 160, first conduit 140, and recess
136. The pressure differential on opposite sides of filter 134 acts
to draw air into recess 136. In addition, the pressure differential
may induce the passage of liquids that are present on the exterior
of filter 134. As such, a filter material should be selected with a
water entry pressure that prevents water from passing through
filter 134 at a pressure differential equal to the vacuum pressure
created by the expansion of pump 160. A greater water entry
pressure, however, may be more desirable. For example, the wearer
of footwear 100 may step into a puddle or immerse footwear 100 in a
lake or pool. In these situations, the static pressure of the water
on the exterior of filter 134 in combination with the vacuum
pressure may create a pressure differential that is significantly
greater than the pressure differential created by vacuum pressure
alone. Accordingly, a filter that prevents the entry of water at
pressures greater than the vacuum pressure of pump 160 may be
necessary to prevent the passage of water in many circumstances.
Note that air flow rate and water entry pressure are generally
inversely related. As such, a filter material having a high water
entry pressure typically has a low air flow rate. One skilled in
the art may reconcile these competing concerns.
[0036] The material selected for filter 134 should also block
particulates that may decrease the aesthetics of footwear 100 or be
detrimental to the performance of first valve 150, second valve
170, or pump 160, including dust, dirt, small rocks, plants,
cosmetics, food, and paint. In general, the smallest visible
particle has a size of approximately 50 microns; bacteria ranges in
size from 0.4 microns to 11 microns; and certain endotoxins average
0.01 microns. As with water entry pressure, an inverse relationship
also exists between the particulate size that may freely pass
through a filter material and the air flow rate. As with water
entry pressure, however, a filter material that blocks relatively
small particles typically has a low air flow rate. Again, one
skilled in the art may reconcile these competing concerns. With
respect to the present invention, an adequate particulate blockage
size may range from 1 to 3 microns.
[0037] With respect to water and other liquids, it is desirable
that filter 134 be both hydrophobic and oleophobic. In other words,
filter 134 should repel water and oil that may build up on the
outer surface. Liquids that adhere to the outer surface may block
pores that would otherwise permit air to pass. In addition, such
liquids are likely to be drawn into the system when the minimum
water entry pressure is exceeded. A filter material that repels
water and oil will, therefore, be less likely to draw water or oil
into the system.
[0038] Finally, filter 134 should operate under a variety of
environmental conditions. In general, the criteria relating to
water entry pressure should be sufficient to prevent water from
entering bladder system 200 during rain or snow conditions. In
addition, filter 134 should be able to function properly following
exposure to temperature extremes, perhaps ranging from negative 10
degrees Fahrenheit to positive 175 degrees Fahrenheit.
[0039] One suitable material for filter 134 is
polytetrafluoroethylene (PTFE) which is disposed on a substrate
material. PTFE exhibits the required characteristics and is
suitably durable when attached to a substrate such as non-woven
polyester. A variation upon the standard formulation of PTFE is
expanded polytetrafluoroethylene (ePTFE) which is manufactured by,
for example, W.L. Gore & Associates. In addition to PTFE, other
suitable materials for filter 134 include high density
polyethylene, ultrahigh molecular weight polyethylene,
polyvinylidene fluoride, polypropylene, and certain ceramic filter
materials. Knit materials, woven materials, nonwoven materials,
laminate structures consisting of one or more differing filter
materials, and paper may also be suitable. In addition, filter
structure 130 may be formed of a solid, porous material.
[0040] First conduit 140 provides a means for air to pass from
recess 136 to pump 160. As depicted in FIGS. 2 and 3, first conduit
140 includes first valve 150. Similarly, second conduit 170
provides a means for air to pass from pump 160 to bladder 190 and
includes second valve 180. First valve 150 and second valve 180 may
be one-way or two-way valves that permit air to pass from recess
136 to pump 160 and from pump 160 to bladder 190, respectively.
Suitable valves include those that are disclosed in the '861, '382,
and '462 patents to Huang; duckbill check valves manufactured by
Vernay; valves manufactured by A.C. Hoffman Engineering Inc.; and
the valves disclosed in U.S. Pat. No. 5,144,708 (patented Sep. 8,
1992 to Robert W. Pekar).
[0041] As noted, first valve 150 may be a one-way or two-way valve.
The primary function of first valve 150 is to prevent the flow of
air from pump 160 to filter 134. Under some circumstances, it may
be desirable to limit the pressure within pump 160. Accordingly, a
two-way valve that permits air to flow from pump 160 to filter 134
only after a predetermined pressure is achieved within pump 160 may
be used.
[0042] The length of first conduit 140 must be sufficient to
connect filter structure 130 with pump 160. As depicted in FIG. 2,
filter structure 130 is located on the instep portion of upper 110
and pump 160 is located in midsole 122. Accordingly, first conduit
140 extends from an edge of midsole 122 and passes through upper
110 to connect with filter structure 130. Filter structure 130 may
be located in a plurality of locations, including, the heel area of
the sole, the medial or lateral side of the ankle region, or on the
interior of upper 110. In determining the locations of first
conduit 140 and filter structure 130, consideration should be given
to the possibility that water or other liquids may contact filter
134. To reduce the probability that filter structure 130 will be
exposed to water, filter structure 130 may be located on portions
of footwear 100 at relatively greater elevations.
[0043] Pump 160 includes a first sheet 161, a second sheet 162, an
inlet 163, and an outlet 164. One purpose of pump 160 is to provide
a volume of less than ambient pressure air that draws air through
filter structure 130 and, thereafter, through inlet 163. The volume
of less than ambient pressure air is created when first sheet 161
and second sheet 162 are separated as midsole 122 expands. As
midsole 122 disengages from the playing surface, the compressive
force decreases, and midsole 122 expands. The expansion of midsole
122 forces first sheet 161 and second sheet 162 to separate,
thereby creating the volume of less than ambient pressure air. A
second purpose of pump 160 is to provide an increase in pressure
that forces air to exit pump 160 through outlet 164 and,
thereafter, enter bladder 190. As midsole 122 contacts the playing
surface and is compressed, the volume between first sheet 161 and
second sheet 162 is decreased, thereby creating a volume of
compressed air that exits pump 160 through outlet 164 and passes
into bladder 190. Note that air will only pass into bladder 190
when the pressure of the air in pump 160 exceeds the pressure of
the air in bladder 190. As noted above, other methods may be used
to expand pump 160.
[0044] The air flow rate required of filter 134 may be dependent
upon the volume of pump 160. In addition, the portion of first
conduit 140 that is between first valve 150 and inlet 163 may also
be added into the volume of pump 160. When midsole 122 is
compressed, the air in this portion of first conduit 140 is also
compressed, thereby adding to the pumping action of pump 160.
Similarly, the portion of second conduit 170 that is between outlet
164 and second valve 180 may also be added into the volume of pump
160.
[0045] Pump 160 and bladder 190 may be manufactured, for example,
using a two-film, blow-molding, or vacuum forming technique. If
manufactured through a two-film technique, bladder 190 may include
a first sheet 191, a second sheet 192, and an inlet 193 that
connects with second conduit 170. In the two-film technique, two
separate layers of elastomeric film are placed one on top of the
other and welded together along the periphery and at predetermined
interior areas. Examples of such bladders and the conventional
welding technique may be found in the '156 and '945 Rudy
patents.
[0046] One advantage of the two-film technique is that it may be
used to integrally form many components of the system being
discussed, including portions of filter structure 130, first
conduit 140, pump 160, second conduit 170, and bladder 190. In
accordance with the two-film technique, elements such as
intermediate sheet 133, filter 134, and valves 150 and 180 are
placed between two layers of elastomeric material which are then
welded using, for example, one or more radio frequency welding
operations. Following the welding operation, excess portions of the
layers may be trimmed and the integrally formed components may be
incorporated into footwear 100. Note that the two-film technique
produces a system wherein first sheet 131, first sheet 161, and
first sheet 191 may be formed from the first layer of the two-film
technique. Alternatively, intermediate sheet 133, first sheet 161,
and first sheet 191 may be formed from the first layer of the
two-film technique. Similarly, second sheet 132, second sheet 162,
and second sheet 192 may be formed from the second layer of the
two-film technique. This continuity decreases the number of joints
and connections between various components, thereby increasing the
durability of the system.
[0047] Bladder 190 may also be manufactured through a blow-molding
technique wherein a liquefied elastomeric material is placed in a
mold having the desired overall shape and configuration of bladder
190. The mold has an opening at one location through which
pressurized air is introduced. The pressurized air forces the
liquefied elastomeric material against the inner surfaces of the
mold and causes the material to harden. Examples of blow-molding
techniques are disclosed in the '861, '382, and '462 patents to
Huang, U.S. Pat. No. 5,353,459 to Potter et al., and U.S. Pat. No.
5,406,719 to Potter, which are incorporated by reference. The '719
patent discloses a technique for forming footwear bladders from
separate sheets. U.S. Pat. No. 5,755,001 to Potter, which is also
incorporated by reference, discloses a footwear bladder and bladder
manufacturing technique wherein outer film layers are sealed
together around their perimeters and are internally connected to
one another by one or more internal sheets which act as tensile
members. Other manufacturing techniques may also be used.
[0048] The material forming bladder 190 preferably prevents
substantial quantities of air from diffusing through first sheet
191 and second sheet 192, thereby ensuring that bladder 190 remains
inflated. Limited diffusion, however, may occur as the system of
the first embodiment will replace escaped quantities of air. In
addition, the material of bladder 190 should remain pliable and
durable at both high and low operating temperatures. Suitable
materials include those disclosed in the '156 and '945 patents to
Rudy. One preferred material is thermoplastic polyurethane.
[0049] The location of bladder 190, as depicted in FIG. 2, is in
the heel region of footwear 100. An example of a suitable heel
bladder 190, which is formed of two sheets of material, is shown in
FIG. 5C. Bladder 190 is sealed around its U-shaped perimeter and
includes linear and dot-shaped welds in interior portions A variety
of bladder shapes, sizes, and locations may be used within the
scope of the present invention. For example, bladder 190 may be
located throughout the length and width of midsole 122, thereby
underlying substantially the entire foot of the wearer. In
addition, bladder 190 may be limited to one side of footwear 100 or
may be located in the forefoot region. Moreover, multiple bladders
may be located within a single article of footwear, a first bladder
in the heel region and a second bladder in the forefoot region, for
example.
[0050] In an exemplar system of the type discussed with reference
to the first embodiment, filter 134 was formed of an expanded PTFE
filter material having an area of 0.88 square inches. This area of
filter 134 was sufficient to provide an air flow rate that inflated
a pump 160 having a volume of 17 cubic centimeters. In turn, the
volume of pump 160 was sufficient to fully inflate a bladder 190
having a volume of 63 cubic centimeters. Duckbill check valves
manufactured by Vernay were used in both the first and second
conduits 140 and 170.
[0051] FIG. 6, which discloses the second embodiment of the present
invention, depicts a cross-section of an article of footwear 100a
having a filter 134a. A pump 160a is located in the forefoot
portion of footwear 100a and a bladder 190a is located in the heel
portion of a midsole 122a. A conduit 160a having a valve 180a
permits air to flow from pump 160a to bladder 190a. Filter 134a is
attached to the upper surface of pump 160a such that air from
within upper 110a may pass through filter 134a and enter pump
160a.
[0052] The purpose of this embodiment is to disclose an alternate
means of inflating a bladder, in this case bladder 190a, to a
pressure that is greater than atmospheric pressure. When footwear
100a is not in contact with the playing surface, midsole 122a and
pump 160a are fully expanded. In this state, pump 160a becomes
filled with air which is at approximately atmospheric pressure.
When footwear 100a contacts the playing surface, the foot of the
wearer covers filter 134a such that air may neither enter nor exit
pump 160a. As impact forces compress midsole 122a, thereby
compressing pump 160a, the pressure of the air within pump 160a
increases and air passes through conduit 170a and valve 180a,
thereby entering bladder 190a. When footwear 100a is lifted from
the playing surface, the wearer's foot uncovers filter 134a, air
enters pump 160a , and the process may repeat. Note that valve 180a
prevents air from exiting bladder 190a.
[0053] The third embodiment, depicted in FIG. 7, includes a filter
material that is used in conjunction with a ventilation system.
Footwear 200 includes an upper 210 and a sole structure 220. The
ventilation system, which may be primarily located in sole
structure 220, includes a filter 230 that permits air to flow into
a first conduit 240. First conduit 240 includes a first valve 250
that permits air to flow into a bladder 260 but not in the reverse
direction. A second conduit 270 leads from bladder 260 to a second
valve 280. Beyond second valve 280, second conduit 270 branches
into a plurality of ventilation conduits 290 that lead to the
interior of upper 210. A plurality of filters 230' cover the ends
of ventilation conduits 290 to prevent liquids and particulates
from entering the system. In the alternative, a single section of
filter 230' may be positioned so as to cover all of the ends of
ventilation conduits 290. The compression of bladder 260 forces air
into ventilation conduits 290 which then enters upper 210, thereby
ventilating the interior of upper 210. As with other
configurations, filters 230 and 230' prevents liquids or
particulates from entering the system.
[0054] Numerous characteristics and advantages of the present
invention have been described in detail in the foregoing
description with reference to the accompanying drawings. However,
the disclosure is illustrative only and the present invention is
not limited to the precise illustrated embodiment. Various changes
and modifications may be effected therein by persons skilled in the
art without departing from the scope or spirit of the present
invention.
* * * * *