U.S. patent number RE37,705 [Application Number 09/491,486] was granted by the patent office on 2002-05-21 for impact absorbing composites and their production.
Invention is credited to Byron A. Donzis.
United States Patent |
RE37,705 |
Donzis |
May 21, 2002 |
**Please see images for:
( Certificate of Correction ) ** |
Impact absorbing composites and their production
Abstract
An improved composite for absorbing and dispersing impacting
forces is disclosed. The composite includes a flexible plastic
enclosure defining an internal cavity. The flexible enclosure is
generally impermeable to air and capable of having its internal
pressure changed. The composite further includes a foam core
filling the cavity and retained within the cavity and adhered on
substantially all of its external surface to the internal surface
of the cavity. The cavity can be pressurized for higher impact
absorbance. Methods for fabricating the composites are disclosed,
as well.
Inventors: |
Donzis; Byron A. (Hunt,
TX) |
Family
ID: |
26796029 |
Appl.
No.: |
09/491,486 |
Filed: |
January 24, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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099368 |
Sep 21, 1987 |
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Reissue of: |
464700 |
Jan 16, 1990 |
05235715 |
Aug 17, 1993 |
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Current U.S.
Class: |
12/142R; 2/465;
264/46.6; 36/71; 36/81; 36/89 |
Current CPC
Class: |
B32B
3/26 (20130101); A41D 31/285 (20190201); F16F
1/37 (20130101); B60R 21/045 (20130101) |
Current International
Class: |
A41D
31/00 (20060101); B32B 3/26 (20060101); B60R
21/04 (20060101); B60R 21/045 (20060101); F16F
1/36 (20060101); F16F 1/37 (20060101); A43B
019/00 (); A41D 013/00 (); B29C 067/00 () |
Field of
Search: |
;12/142R
;36/37,89,92,81,71,82,138,44 ;2/465,22 ;264/46.6,45.1,46.8
;5/434,481,443,473 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2217759 |
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Oct 1973 |
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DE |
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24020 |
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1907 |
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GB |
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861983 |
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Mar 1961 |
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GB |
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Primary Examiner: Kavanaugh; Ted
Parent Case Text
This is a continuation of copending application Ser. No. 07/099,368
filed on Sep. 21, 1987, now abandoned.
Claims
What is claimed is:
1. A method for producing a shock absorbing composite and
dispersing impacting forces comprising
forming a plastic enclosure having a shock absorbing configuration
and defining an internal cavity therein,
placing within said enclosure a foam core filling said cavity,
retaining said core within said cavity such that the composite is
generally impermeable to air but includes means for adding and
removing pressurizing fluid from the internal cavity and such that
the enclosure and the core are prestressed by one another, the core
adhered on substantially all of its external surface with a heat
activated adhesive to the internal surface of the enclosure,
and
pressurizing the core through said means for adding and removing
pressurizing fluid from the internal cavity to a value between 0
and 20 psig effective to provide efficient impact absorption.
2. A method for producing a shock absorbing composite for absorbing
and dispersing impacting forces comprising
forming a flexible plastic enclosure having a shock absorbing
configuration and defining an internal cavity therein, impermeable
to air
placing within said enclosure a preshaped foam core partially
filling said cavity,
forming in situ between said enclosure and said preshaped foam core
a further foam core filling said cavity and joining substantially
all of the core's external surface to the internal surface of the
enclosure, retaining said cores within said cavity such that the
composite is generally impermeable to air and capable of having its
internal pressure changed and the enclosure and the core are
prestressed by one another, and
pressurizing the core to a value between 0 and 20 psig effective to
provide efficient impact absorption.
3. A method for producing a shock absorbing composite for absorbing
and dispersing impacting forces comprising
forming a flexible foam core shaped and sized as required for said
shock absorbing composite,
applying to the outer surface of said core a flexible plastic layer
thereby forming a flexible enclosure surrounding and adhered on all
sides to said core, said flexible enclosure and said core being
generally impermeable to air and capable of having its internal
pressure changed, and
pressurizing the core to a value between 0 and 20 psig effective to
provide efficient impact absorption.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to improved impact absorbing compressible
composites. These composites can be shaped into smooth compound
curves and find application wherever high efficiency impact
absorption is called for such as in athletic wear, in seating
system, in vehicle interior padding materials and the like.
2. Background Information
There is a well-recognized need for high performance materials for
spreading or absorbing impacts. In recent years, athletes, athletic
equipment manufacturers and sports medicine professionals have
recognized the need for improved impact absorbing materials in
athletic equipment. These materials find application as heel pads
and foot sole pads in shoes to absorb the shock of foot strike and
as cushioning points under football or hockey pads such as shoulder
pads, thigh pads, hip pads and the like to name but a few typical
applications. Similar needs may be found in seating systems and in
vehicle interiors, to name but a few representative fields in which
impact absorption is a major interest.
One common approach to impact absorption in the past has involved
using felts or blocks of a soft padding material. Padding materials
known heretofore include cotton padding, horsehair padding, foam
rubber, foamed plastics, sponge rubber and the like. In these
designs, the inherent resilience of the padding material is
employed to absorb and disperse the applied impact. These designs
have the disadvantage that they often "bottom out" or fully
compress on severe impacts of the type regularly encountered during
use such as in athletic equipment or in vehicle interiors and thus
provide minimal protection. When made thicker to avoid this
problem, they become cumbersome and can interfere with the design
of the article being padded, and in the case of athletic equipment
can interfere with the wearer's freedom and performance.
Impact absorbers have also been proposed which employ fluid-filled
bladders such as cushioning air sacks These devices rely upon the
compressibility of the enclosed fluid to provide the desired shock
absorbing. In some embodiments of these devices, the fluid is fully
enclosed and can not escape. In others, the fluid is gradually and
controllably forced out of the bladder during the impact with the
rate of release being selected to prevent exhaustion of the fluid
during the impact event. While effective as shock absorbers, these
devices can have the failing of ballooning or otherwise expanding
in one region when another region is being compressed. This can
lead to discomfort or at minimum give an unnatural or unstable feel
to the user. In the case of footwear, this problem can lead to an
unstable foot plant with increased opportunity for injury. Another
issue with this type of pad has related to problems in forming
shapes based on compound curve and to retaining structural
integrity with the above-described ballooning.
Representative patents in the field of shock absorbing or impact
absorbing devices include U.S. Pat. No. 4,513,449, SHOCK ABSORBING
ATHLETIC EQUIPMENT; U.S. Pat. No. 4,370,754, VARIABLE PRESSURE PAD;
U.S. Pat. No. 4,453,271, PROTECTIVE GARMENT; U.S. Pat. No.
4,217,705, SELF-CONTAINED FLUID PRESSURE FOOT SUPPORT DEVICE, all
issued to Donzis, U.S. Pat. No. 4,446,634 for FOOTWEAR HAVING
IMPROVED SHOCK ABSORPTION; U.S. Pat. No. 4,397,104 for INFLATABLE
SOLE-SHOE; U.S. Pat. No. 2,863,230 for CUSHIONED SOLE AND HEEL FOR
SHOES; U.S. Pat. No. 4,229,889 for PRESSURIZED POROUS MATERIAL
CUSHION SHOE BASE; U.S. Pat. No. 4,637,716 for METHOD FOR MAKING
ELASTOMERIC SHOE SOLES; U.S. Pat. No. 4,635,384 for FOOTWEAR SOLE;
U.S. Pat. No. 4,610,099 for SHOCK-ABSORBING SHOE CONSTRUCTION; and
U.S. Pat. No. 4,571,853 for SHOE INSERT.
It is an object of the present invention to provide an improved
impact absorbing composite. It is desired that this composite
provide superior shock absorbing performance and also be capable of
being formed into complex compound curve shapes, be durable and
hygienic.
STATEMENT OF THE INVENTION
An improved impact absorbing composite has now been found. This
composite is capable of dispersing and absorbing impacting forces
with high efficiency. The composite is characterized by a structure
including a flexible plastic wall (enclosure) defining an internal
cavity. This flexible enclosure is made of a material that is
generally impermeable to air and is capable of having its internal
pressure changed. The internal cavity of the enclosure is filled
with a foam core. This core is held in place by the cavity walls.
Importantly, the core is intimately adhered (glued, bonded or the
like) on substantially all of its external surfaces to the internal
surface of the cavity. In preferred embodiments, the wall and the
core are prestressed by one another. That is, the core presses out
against the wall and the wall pushes in against the core. The
intimate adherent contact between the foam core and the outer wall
gives rise to an unexpected degree of product integrity and
unexpectedly superior impact absorbing capabilities.
In preferred embodiments, the composite has a valve or fitting
communicating with the cavity so that the pressure within the
cavity can be altered. This permits the composite to be adjusted to
accommodate varying impacts. The invention can thus include in
combination such a composite together with a device for
pressurizing its cavity.
Also in preferred embodiments, the foam core is an open-celled foam
or a reticulated foam so that the pressure within the core is
uniform. Urethane polymers have been found to be excellent for
forming the cavity and the foam and are preferred materials of
construction.
In other aspects, the composites of the invention can employ cores
having a plurality of different foams arranged parallel or
perpendicular to the impact direction. This permits differing
densities and impact resistances to be present at different
positions on the composite. The impact absorbers of this invention
can be used in conjunction with other materials or layers including
without limitation, cosmetic or hygienic over-layers, other
shock-absorbing layers or the like.
In yet another aspect, this invention provides a variety of methods
for fabricating these composites. All of these methods are
characterized by creating an adherent bond between the foam core
and the outer layer and by pressurizing the core to a value
effective to provide efficient impact absorption.
One such method involves shaping the wall surface to create a
cavity, sizing and shaping the foam core so as to fully fill the
cavity and preferably prestress the wall and core, adhering and
enclosing the core within the cavity and adjusting the pressure
within the cavity to a value effective to provide efficient impact
absorption.
Another fabrication method involves shaping the wall surface to
create a cavity, sizing and shaping the core so as to partially
fill the cavity, placing the core within the cavity, forming an
elastomeric foam and preferably an open-celled or reticulated foam
in situ within the cavity so as to fill the space between the
preshaped foam and the cavity wall and to adhere the cavity wall to
the core and preferably prestress the wall and core, and adjusting
the pressure within the cavity to a value effective to provide
efficient impact absorption.
Yet another fabrication method involves shaping the wall surface to
create a cavity, forming a cavity-wall-adherent open-celled or
reticulated foam core in situ within the cavity so as to fill the
cavity and preferably prestress the wall and core, and adjusting
the pressure within the cavity to a value effective to provide
efficient impact absorption.
A further fabrication method involves sizing and shaping the foam
core, forming the outer wall in situ around and adherent to the
foam core such as by shrinking a film a core-adherent material
around the core or by applying a layer of uncured wall material,
such as a solution of wall-forming polymer, around and adherent to
the core and then curing the uncured wall material, thereby
creating a cavity enclosing and preferably prestressing the core,
and adjusting the pressure within the cavity to a value effective
to provide efficient impact absorption.
The present shock absorbing composite can be employed in a wide
range of applications. One excellent application is as heel pads
and/or sole pads for shoes, especially sport shoes, where they
serve to absorb foot strike impact with high efficiency.
The composites of this invention are characterized by being easily
formed in compound curve forms, by being very light weight and by
being hygienic. They are further characterized by being adjustable
in pressure, and thus in impact cushioning capacity. This permits
them to serve in a wide range of applications with widely variable
impacts.
DETAILED DESCRIPTION OF THE INVENTION
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described herein with reference being
made to the accompanying drawings. Where practical in the drawings,
a common reference numeral is used for the same part when it
appears in more than one Figure. In the drawing:
FIG. 1 is an exploded perspective view of the components of an
impact absorber of this invention;
FIG. 2 is an cut away cross-sectional view of a shock absorber of
this invention;
FIG. 3 is a partially schematic cross sectional view of an impact
absorbing heel pad not embodying this invention. This heel pad has
a wall defining a pressure-tight cavity but does not have a foam
core adhered to and filling its inner surface. This figure
illustrates the flaw in this design that an impact can be absorbed
but at the same time ballooning occurs;
FIG. 4 is similar to FIG. 3 but illustrates that with the present
invention ballooning is prevented;
FIG. 5 is a perspective view of an alternative foam core for use in
this invention. This core has a plurality of differing compression
strength foams arranged parallel to the impact force;
FIG. 6 is a cut away cross-sectional view of another alternative
embodiment of the impact absorber of this invention in which the
wall material defining the cavity is further shaped to provide a
supportive column;
FIG. 7 is another cross sectional view of the absorber shown in
FIG. 6 taken along line 7-7';
FIG. 8 is an exploded perspective view of the components of the
absorber of FIGS. 6 and 7;
FIG. 9 is a perspective view of an alternative embodiment of the
impact absorber of this invention. This embodiment employs a core
which has a plurality of differing compression strength foams
arranged perpendicular to the impact force;
FIG. 10 is a phantom top view of a core configuration for use with
closed cell foam materials;
FIG. 11 is a cross sectional view of the core shown in FIG. 10
taken along line 11-11';
FIG. 12 is a phantom top view of another core configuration for use
with closed cell foam materials;
FIG. 13 is a cross sections view of the core shown in FIG. 12 taken
along line 13-13';
FIG. 14 is a cut away cross sectional view of a shoe containing a
shock absorber of the present invention and additionally having a
pump for pressurizing the core of the absorber;
FIG. 15 is a cross sectional view of an automotive dash board
incorporating an impact absorber of this invention;
FIGS. 16 and 17 are two views of an additional representative
application for the shock absorbers of this invention as a foot
pad;
FIG. 18 is a perspective view of a shoulder pad under pad
application for the shock absorbers of this invention; and
FIGS. 19 and 20 are graphs illustrating the effectiveness of the
impact absorbers of this invention and their adaption to various
body weights and to various impacts.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1 and 2 in more detail, these figures illustrate
an impact absorber 10. Impact absorber 10 includes a foam core 11
and top and bottom wall sections 12 and 14 which when joined define
a cavity 15. A layer of adhesive .[.16.]. .Iadd.17 .Iaddend.is
present between essentially all of the inner surface of cavity 15
and the outer surface of foam core 11. This layer is shown on core
11 but could as well be on the inside surface of the wall or on
both the core and the wall as desired. When wall sections 12 and 14
are joined, the cavity which they define is pressure tight. It is
possible to equip the impact absorber with a valve or fitting such
as valve 16. Valve 16 is a "Halkey-Roberts" type urethane valve
which is shown in FIG. 1 is its pre-assembly form. After
incorporation, the top end of valve 16 is cut off flush with the
surface of the shock absorber as shown in FIG. 2. Any equivalent
form of valve or pressure control aperture can be used, if desired.
This valve allows the pressure in the interior (cavity 15) of the
impact absorber to be adjusted, as desired, by adding or removing
fluid from the cavity.
The outer wall of the impact absorber is formed of flexible
plastic. The materials used to form the wall can be selected from
the film-forming flexible plastics. Virtually any plastic can be
used so long as it is resistant to bacterial attack, flexible and
shapable into the forms and configurations desired. Useful
film-forming plastics include poly(urethane)s both of the
poly(ether) and the poly(ester) form, poly(ester)s such as
poly(ethylene terphthalate), flexible poly(vinyl)s, elastomeric
poly(olefin)s such as poly(isoprene), poly(isobutylene), and
neoprene, low density poly(ethylene)s and the like.
In the embodiment shown in FIGS. 1 and 2, the outer wall is
preshaped into the desired configuration and then the foam core is
adhered to it. In another embodiment, the outer wall can be formed
around the foam core. One way to accomplish this is to use a liquid
polymer precure solution or suspension which is applied to the
outer surface of the core and then cured. Another way to accomplish
this is to use plastic sheet stock and laminate it to the core or
shrink it around the core. In any of these alternative modes of
construction, it is essential that there be a strong adherent bond
between the wall and essentially the entire outer surface of the
core.
Of the plastics useful in forming the films, preference is given to
the flexible poly(urethane)s because of their ready availability.
These materials are available from J. P. Stevens Company and
Deerfield Urethane, Inc., to name but two regular suppliers.
Representative useful plastic films include the Deerfield
"Dureflex" poly(urethane) films. These materials can be preformed
as in FIGS. 1 and 2 or they can be used as stock goods. When a
liquid is used to apply the outer wall, it is typically a solution
of a prepolymer or resole resin. Vinyl films can be used in this
application. A typical vinyl film is the vinyl adhesive sealant
produced by W. R. Grace and marketed by Eclectic Products as
Eclectic 6000 adhesive sealant. These materials are solvented in
halocarbons such as perchloroethylene and the like. A preferred
liquid coating is based on the polyurethanes. Again, the nonrigid
urethane polymers are preferred. The solutions known in the art for
forming flexible urethane films are very suitable for this
application. Typical urethane polymer solutions include the
reaction product of a diisocyanate such as toluene diisocyanate or
hexamethylene diisocyanate with a polyol such as a polyether
polyol. These reaction products are commonly produced in a mixed
solvent system such as a polar solvent (for example, Butyl
Cellosolve, Cellosolve Acetate, butyl Carbitol, or diacetone
alcohol or the like) in combination with an aromatic solvent such
as toluene, benzene, or hydrocarbon distillate fractions heavy in
aromatics and having a boiling range in the range of from about
140.degree. to 240.degree. C. This outer wall, when applied as a
liquid can be dried (solvent removed) and cured by the application
of heat and/or the application of a curing catalyst such as an
amine. Other curing modalities such as photocuring can be employed
as well, if appropriate. The liquid wall-forming compositions can
contain plasticizers and builders and the like, if desired. The
particular conditions used for forming the outer wall are
conventional for processing polymers such as the urethanes which
are preferred and are known to those of skill in the polymer
arts.
The outer wall, whether supplied as a preformed structure, a cured
liquid overcoat or a shrunk or adhered layer of stock goods is
commonly from about 1 to 200 mils in thickness with thicknesses in
the range of from about 2 to 50 mils being preferred and excellent
results being attained with thicknesses of from about 3 to about 35
mils.
The core of the impact absorber is a foam. This foam is preferably
on open-celled foam, that is a foam in which the various cells are
in communication with each other and with the outer surface of the
foam. Similar properties are achieved with a reticulated foam, that
is a foam which has been treated to break down membranes which
separated various cells. Foam rubber, foamed latex, vinyl foams and
the like can be used. The preferred foam material for use in the
core is poly(urethane) foam. Representative foams include the
"Ensolite" foams sold by Uniroyal Plastics Co., Inc. and the
flexible urethane foams sold by the E. R. Carpenter Company.
Typical densities for the foam core range from between about 0.5 to
about 15 pounds per cubic foot. Preferred foam densities are from
about 2 to 10 pounds per cubic foot.
It will be appreciated that because the foam core is adhered to the
outer wall it is in effect a structural member. The adhered foam
serves to prevent the ballooning of the device as previously
described. This duty puts strain upon the foam of the core. If the
foam separates under this strain it can result in a loss of
integrity of the device. With this potential problem in mind, it is
possible to reinforce the foam by including filaments or fibers or
fabrics in it. Typical reinforcements an be inorganic materials
such as fiberglass or carbon fiber; natural organic fibers such as
silk, cotton, wool or the like or synthetic organic fibers such as
urethane fibers, nylon filaments, nylon fabrics, aramid filaments
and fabrics, and the like. This reinforcement can be laminated into
the foam, incorporated into the foam or otherwise compounded into
the foam as is known by those skilled in the art.
In the embodiment shown in FIGS. 1 and 2, the internal foam core is
preshaped to fit tightly within the outer wall of the impact
absorber.
This intimate fit may be accomplished in other ways as well. For
one, the core can be foamed in place within the wall structure
using injectable flexible foam forming materials known in the art.
With the preferred urethane foams, a typical foaming mixture can
include a polyether polyol, a diisocyanate such as toluene
diisocyanate, water, and amine and organotin catalysts. This
mixture generally contains polymeric fillers and flexibilizers
(plasticizers) as well. The added water reacts with the isocyanates
to produce an amine plus carbon dioxide gas which foams the liquid.
Other foaming agents such as gases including carbon dioxide,
nitrogen, air or the like as well as low boiling liquids, (commonly
low-boiling fluorocarbons and the like) can also be added. By
controlling the amount of foaming material added and the cure
conditions, the core so formed can, if desired, prestress the outer
wall as is preferred. The in situ cores can be closed-cell foams,
open-celled foams or reticulated foams as desired.
In a hybrid form of construction, the foam core can be a composite
of a preshaped foam body which does not completely fill the cavity
created by the outer wall and an added foam-in-place layer between
the wall and the preshaped body. This form of fabrication has the
advantage that the desired intimate fit is achieved with a minimum
of preshaping and fitting while at the same time the preshaped core
provides a measure of dimensional stability and integrity to the
composite during fabrication.
The third component of the impact absorbers of this invention is an
adhesive for affixing the foam core to the wall. This adhesive is
most conveniently an activated adhesive such as a light activated
adhesive, UV activated adhesive or heat activated adhesive so as to
permit the parts to be fitted together and then bonded. A typical
heat-activated adhesive is the Royal Adhesive DC-11324 material
sold by Uniroyal. This adhesive is a two part
poly(urethane)/isocyanate adhesive which has the added advantage of
being water-based. When applied to the foam and/or wall it dries to
a non-tacky surface which permits easy assembly. This material
heat-activates at 300.degree.-325.degree. F. to form a tough
adherent bond. Other useful adhesives can include epoxy adhesives,
contact cement type poly(urethane) adhesives such as the Uniroyal
"Silaprenes", the 3M "Scothgrip" adhesives and the isoprene contact
cements. In general one can employ as adhesive any material which
will bond the foam to the outer wall with a strength which will not
be exceeded by the forces of impact applied to the impact absorber
or by the forces applied by the pressure applied to the impact
absorber.
If the fabrication methods in which a liquid solution of prepolymer
is applied to the core to create the outer layer or in which the
core is foamed in place, it is often the case that the required
intimate bond between the core and the outer wall is formed
directly without the need for added adhesive.
The outer wall portions of the impact absorber are joined together
such as by the use of adhesive or by heat sealing or the like to
give a fluid impermeable wall to which the inner core is bonded.
After the fusing together of the wall components, the impact
absorber can be trimmed and, if desired, further shaped to conform
to the environment of use.
The core of the present impact absorbers contain a fluid. Gases and
in particular air are very suitable fluids. Liquids and .[.gells.].
.Iadd.gels .Iaddend.could be used as well, if desired.
Turning to FIGS. 3 and 4, the advantages of the impact absorber of
this invention are graphically illustrated. In each of these
figures a shoe 30 is shown together with foot 31 impacting downward
into a heel pad shown as 32 (in FIG. 3--not according to the
invention) and as 10 (in FIG. 4--in accord with this invention). In
the case of heel pad 32, the downward pressure of the heel causes
the center of the pad 34 to be severely depressed while permitting
the edges 35 and 36 to balloon up. This can be uncomfortable and
unstable. With pad 10 the center 33 depresses somewhat but there is
minimal ballooning.
Turning now to FIG. 5, a variation of the core 11 is shown. This
core (core 50) is fabricated from a plurality of foams of differing
properties, for example density. As shown, the core includes a
series of plugs 51A, 51B, etc of firm density foam inserted into
the body of core 11. This can result in a light weight core having
the firmness of the plugs. This is merely a representative
configuration and one could as well have one entire section of the
core with one density foam and another section with another
density. One could also vary the core based on other properties,
such as the ability of a region of the foam to take a set or the
like. The various core sections are adhered to the outer wall of
the impact absorber as is shown in FIGS. 1 and 2. One could form a
core of this type by placing preshaped pieces of one foam in the
cavity and then foaming in place the other material, if
desired.
The plastic wall of the impact absorber can have structural
properties and contribute to the rigidity and shock absorbing
properties of the device. FIGS. 6, 7 and 8 illustrate an embodiment
60 of the impact absorber which includes a depression or "column"
61 in its structure so as to provide additional wall surface and
structure in that region of the absorber. In this embodiment as
shown in FIG. 8, the valve 16 is illustrated being laminated into
the composite as the top 12 is joined to the bottom 14.
FIG. 9 illustrates other variations which may be employed without
departing from the spirit of this invention. FIG. 9 shows impact
absorber 80. The foam core of absorber 80 is fabricated from
several different foams including foam section 81, section 82,
section 83 and section 84. These sections are all adhered to the
wall 12/14. Valve 16 is again provided to permit the pressure of
the core to be altered and controlled. The various core sections
can be adhered to one another, if desired. If they are adhered to
one another, it must be borne in mind that the glue layers of the
like between the various sections can serve as barriers for the
transport of fluid between the various sections. If such fluid
communication is desired, gaps must be left in the glue layers or
glues which are fluid-permeable must be used.
Absorber 80 includes several other features which can be
incorporated into the present absorbers. An exterior pad 85 is
provided. This can provide additional shock absorbancy. A top layer
86 is also present. This can be a cosmetic over layer or can be
provided as a replaceable hygienic layer.
In the absorbers shown in FIGS. 1, 6 and 9, the means for adjusting
the pressure (valve 16) has been in communication with the foam
core itself and has relied upon the open-cell foam structure of the
core to distribute the applied pressure throughout the core and
thus provide a uniform level of support throughout the absorber.
While this structure is very suitable, one can also employ
closed-cell foams, if desired. FIGS. 10 and 11, and FIGS. 12 and 13
respectively illustrate two representative configurations for a
closed-cell foam core. In the configuration shown in FIGS. 10 and
11, the core 87 contains an aperture 88 into which the pressure
adjusting valve 16 can fit. This aperture 88 communicates with a
network of channels 89 spaced throughout the core so as to transmit
and distribute the pressure applied to aperture 88. In this
embodiment, the network of channels is contained by and enclosed by
the closed-cell foam core. This means that the core itself can
contribute to the containment of the pressure applied to the
channels. This offers the advantage that localized stress on the
outer wall is avoided or minimized and possible failures due to
rupture at localized stress points are minimized.
The configuration shown in FIGS. 12 and 13 is substantially the
same as that shown in FIGS. 10 and 11 with the exception that
aperture 97 communicates with a network of passages 98 which are
not fully contained within the core. This configuration of FIGS. 10
and 11 but would be less expensive and simpler to produce.
Turning to FIG. 14 an additional embodiment of the impact absorber
is shown as foot pad 90 housed within the sole portion of shoe 95.
Foot pad 90 includes the foam core 11 and adherent outer wall 12/14
described herein. Pad 90 is equipped with a built in pump to alter
the pressure within its core. This pump includes a one way check
valve 16 which admits air into pump cavity 91. Pump cavity 91 is
compressed and released to give a region of low pressure so that
air can enter through valve 16. When the cavity 92 is depressed
again, this forces the newly admitted air through passage 92 into
the core 11, thus increasing its pressure. This process is repeated
until the proper pressure is attained. Shoe 95 also includes a
collar 93. This can be formed with the same structure as pad 90
with an internal core adhered to the walls. Such a collar would be
very effective at absorbing the shock which would occur as the
wearer's foot comes up in the shoe and impacts it or would be
effective as a protection to the wearer's ankle and achilles tendon
region.
FIG. 15 illustrates that the present invention finds application in
many areas beyond athletic equipment. It illustrates an automotive
dashboard structure 101 having an impact pad 100 on its face as
well as phantom steering wheel 102. Impact pad 101 includes core
11, wall 12/14 and valve 16. Such a pad can provide efficient
dashboard impact protection for the occupants of the automobile in
the event of a crash.
FIGS. 16 and 17 illustrate in two views a ventilated footpad 110
for use in shoes. Pad 110 has a complex shape which requires
numerous compound curves. In its application as a shoe footpad, pad
110 will be subjected to a wide variation in impacts depending upon
the weight of the runner using it and the runner's lightness of
footstrike. It is of substantial advantage to adjust the pressure
within the pad with valve 16 to accommodate these variations.
FIG. 18 illustrates another embodiment of the present invention, an
underpad 180 for use in conjunction with contact sports shoulder
pads. Underpad 180 has a structure which includes numerous compound
curves and a plurality of "Swiss-cheese" holes through its
structure. The compound curve-forming ability and the plurality of
holes permit the pad to conform to and bend over the wearer's
shoulder with comfort and breathability. It is a special advantage
that the present invention makes these complex curves possible and
provides superior shock and impact absorption in such settings.
The effectiveness of the present invention can be demonstrated by
comparative tests. A series of impact tests were run on a standard
state-of-the-art basketball shoe. The same tests were then
performed on the same model shoe which had been modified by
replacing a portion of its sole structure (the heel pad region)
with an impact absorber of this invention. The impact absorber was
fabricated from 35 mil flexible poly(urethane). The core was about
1/2+L inch thick open-cell poly(urethane) foam of 5 lbs per cubic
foot density. The foam core slightly prestressed the outer wall by
being somewhat oversized and was adhered to the walls using a heat
activated waterbased urethane adhesive. Tests were run with the
core sealed at atmospheric pressure and with the core pressurized
to 5 and 10 psig. FIGS. 19 and 20 present the results of these
tests. In each figure line A is the results observed with the prior
art shoe. It can be seen that for a given application of energy to
the shoe, i.e. a given impact, the shoe transmits a certain peak
force and a certain acceleration, (in G's) to the wearer. Lines B
show the results achieved when the atmospheric bladder is used.
They show that the force and acceleration transmitted to the wearer
is significantly reduced. Importantly, this reduction occurs over
the entire range of applied energies. Thus the effectiveness of the
present absorbers is substantially universal and will be observed
with hard impacts such as may result with heavy athletes and also
with lighter impacts such as may result with lighter weight
athletes, etc.
Lines C show that even better shock absorbancy is achieved when a
positive pressure is applied to the bladders. Similar results were
obtained with the 5 and 10 pound pressures which suggest that in
practical terms these pressures may be quite adequate. On the basis
of these tests, it is believed that pressures in the range of 0 to
about 20 psig are preferred.
The present invention has been described herein in detail with
respect to a number of preferred embodiments and configurations. It
will be appreciated, however, that modifications and changes to
various aspects of these embodiments may be made while still coming
with in the spirit and scope of this invention which is as defined
by the following claims.
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