U.S. patent application number 11/815486 was filed with the patent office on 2008-10-23 for air venting, impact-absorbing compressible members.
This patent application is currently assigned to XENITH, LLC.. Invention is credited to Vincent R. Ferrara.
Application Number | 20080256686 11/815486 |
Document ID | / |
Family ID | 36384460 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080256686 |
Kind Code |
A1 |
Ferrara; Vincent R. |
October 23, 2008 |
Air Venting, Impact-Absorbing Compressible Members
Abstract
An impact-absorbing compressible member includes a thin-walled
enclosure defining an inner chamber containing a volume of fluid
such as air. The enclosure includes one or more orifices which as
sized and positioned to allow air to vent from the inner chamber in
response to an impact on the member and to refill the inner chamber
in response to an impact on the member and to refill the inner
chamber after the impact is released. The enclosure is formed of a
blow-molded thermoplastic elastomer (TPE) material which is
economical to make and durable in use. The compressible members can
be used as building blocks for impact-absorbing shell structures
for a wide variety of application such helmets, protective pads for
body parts, sports arena wall padding, vehicular bumpers,
dashboards and the like. The compressible member has
impact-absorbing advantages over conventional foams currently used
in those applications.
Inventors: |
Ferrara; Vincent R.;
(Wellesley, MA) |
Correspondence
Address: |
CESARI AND MCKENNA, LLP
88 BLACK FALCON AVENUE
BOSTON
MA
02210
US
|
Assignee: |
XENITH, LLC.
Boston
MA
|
Family ID: |
36384460 |
Appl. No.: |
11/815486 |
Filed: |
February 16, 2006 |
PCT Filed: |
February 16, 2006 |
PCT NO: |
PCT/US06/05857 |
371 Date: |
August 3, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11059427 |
Feb 16, 2005 |
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11815486 |
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60654225 |
Feb 18, 2005 |
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60654194 |
Feb 18, 2005 |
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60654128 |
Feb 18, 2005 |
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Current U.S.
Class: |
2/413 |
Current CPC
Class: |
B60R 19/20 20130101;
B60R 2019/1893 20130101; A42B 3/065 20130101; A63B 2071/0063
20130101; A63B 71/0054 20130101; A63B 71/10 20130101; F16F 13/08
20130101; F16F 7/128 20130101; B60R 21/045 20130101; B60R 2021/0407
20130101; A63B 71/081 20130101; A41D 13/0155 20130101; A41D 31/285
20190201; F16F 9/0481 20130101; A42B 3/121 20130101; F16F 7/12
20130101 |
Class at
Publication: |
2/413 |
International
Class: |
A42B 3/00 20060101
A42B003/00 |
Claims
1. An impact-absorbing, compressible member comprising: an
enclosure having a thin wall and an uncompressed configuration
which defines a hollow inner chamber; a volume of fluid at least
partially filling said inner chamber; at least one orifice in the
enclosure wall which communicates with said inner chamber; said
enclosure being sized and adapted to collapse at a first rate when
the member is subjected to a relative high energy impact and to
collapse at a lesser rate when the member is subjected to a lesser
energy impact.
2. The compressible member of claim 1 in which said thin enclosure
is formed of a thermoplastic elastomer (TPE) material.
3. The compressible member of claim 2 in which said enclosure is
formed by blow-molding the TPE material into the uncompressed
configuration of said enclosure.
4. The compressible member of claim 2 in which said fluid is
air.
5. The compressible member of claim 1 including at least first and
second separate orifices through the wall of said enclosure, the
first orifice permitting fluid to exhaust from the inner chamber at
a first rate in response to the impact on said member, and the
second orifice permitting fluid to flow into the inner chamber at a
second rate different from the first rate following the impact.
6. The compressible member of claim 5 in which the first orifice
comprises a plurality of spaced, relatively small openings in the
wall of said enclosure.
7. The compressible member of claim 5 in which the second orifice
includes a one-way valve permitting fluid to flow into the inner
chamber and resisting fluid flow out of the inner chamber.
8. The compressible member of claim 5 in which the second orifice
is sized to adjust the rate at which the fluid flows into the inner
chamber relative to the rate at which the fluid flows out of the
inner chamber through the first orifice.
9. The compressible member of claim 1 in which said enclosure has a
bellows-like wall construction to facilitate collapse of said
enclosure in response to the impact.
10. The compressible member of claim 1 in which the at least one
orifice is sized such that, when the impact is of relatively high
energy, said enclosure collapses with sufficiently high resistance
to convert energy of the impact to heat in said enclosure.
11. The compressible member of claim 1 in which said wall is
elastic and the at least one orifice is in the form of a slit or
slits in the wall of said enclosure, which due to the elasticity of
the enclosure wall elastically varies or vary in size or shape in
response to the impact.
12. An energy-absorbing shell structure comprising a plurality of
energy-absorbing compressible members as defined in any of claims 1
through 11 arranged in a layer, and at least one additional layer
secured to corresponding parts of said compressible members.
13. The structure of claim 12 wherein said plurality of
compressible members are disposed between said at least one
additional layer and a second layer.
14. The structure of claim 12 or 13 configured as a protective
helmet for a wearer's head.
15. The structure of claim 12 or 13 configured as a protective pad
for a wearer's body part.
16. The structure of claim 12 or 13 configured as a protective pad
for a sports arena barrier.
17. The structure of claims 12 or 13 configured as a bumper on a
vehicle.
18. The structure of claim 12 or 13 configured as a protective
covering on a vehicle dashboard.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application
claiming priority to my co-pending U.S. patent application Ser. No.
11/059,427, filed Feb. 16, 2005, titled "Multi-Layer Air-Cushion
Shell With Energy-Absorbing Layer For Use in the Construction of
Protective Headgear." The entirety of this patent application is
incorporated by reference herein.
[0002] This application also claims priority to my Provisional
Application No. to 60/654,225, filed Feb. 18, 2005, titled
"Compressible Air Cushion Technology For Use In Protective Body
Equipment," my Provisional Application No. 60/654,194, filed Feb.
18, 2005, titled "Compressible Air Cushion Technology For Use In
Sports Arenas," and my Provisional Application No. 60/654,128,
filed Feb. 18, 2005, titled "Vehicular Uses Of Compressible Air
Cushion Technology." The entireties of these provisional
applications are also incorporated by reference herein.
[0003] This application is also related to my PCT application filed
concurrently herewith, titled "Energy-Absorbing Liners For Use With
Protective Headgear" (Cesari and McKenna, LLP Docket No.
104208-0019). The entirety of this application is also incorporated
by reference herein.
BACKGROUND OF THE INVENTION
[0004] 1. Field of the Invention
[0005] The invention relates generally to thin-walled,
impact-absorbing compressible members. More specifically, the
invention relates to an air venting, impact-absorbing compressible
member, preferably fabricated from thermoplastic elastomer (TPE)
material, that can be used in the construction of a wide variety of
shock-absorbing and/or impact protective devices, including,
without limitation, protective headgear, protective pads for other
parts of the body, protective padding for sports arenas such as
hockey rink boards and the like, and impact-absorbing devices for
vehicles such as bumpers, dashboards and the like.
[0006] 2. Background Information
[0007] Concussions, also called mild traumatic brain injury, are a
common, serious problem in sports known to have detrimental effects
on people in the short and long term. With respect to athletes, a
concussion is a temporary and reversible neurological impairment,
with or without loss of consciousness. Another definition of a
concussion is a traumatically induced alteration of brain function
manifested by 1) an alteration of awareness or consciousness, and
2) signs and symptoms commonly associated with post-concussion
syndrome, such as persistent headaches, loss of balance, and memory
disturbances, to list but a few. Some athletes have had their
careers abbreviated because of concussions, in particular because
those who have sustained multiple concussions show a greater
proclivity to further concussions and increasingly severe symptoms.
Although concussions are prevalent among athletes, the study of
concussions is difficult, treatment options are virtually
non-existent, and "return-to-play" guidelines are speculative.
Accordingly, the best current solution to concussions is prevention
and minimization.
[0008] Concussion results from a force being applied to the brain,
usually the result of a direct blow to the head, which results in
shearing force to the brain tissue, and a subsequent deleterious
neurometabolic and neurophysiologic cascade. There are two primary
types of forces experienced by the brain in an impact to the head,
linear acceleration and rotational acceleration. Both types of
acceleration are believed to be important in causing concussions.
Decreasing the magnitude of acceleration thus decreases the force
applied to the brain, and consequently reduces the risk or severity
of a concussion.
[0009] Protective headgear is well known to help protect wearers
from head injury by decreasing the magnitude of acceleration (or
deceleration) experienced by the wearers. Currently marketed
helmets primarily address linear forces, but generally do not
diminish the rotational forces experienced by the brain. Helmets
fall generally into two categories: single impact helmets and
multiple-impact helmets. Single-impact helmets undergo permanent
deformation under impact, whereas multiple-impact helmets are
capable of sustaining multiple blows. Applications of single-impact
helmets include, for example, bicycling and motorcycling.
Participants of contact sports, such as hockey and football, use
multiple-impact helmets. Both categories of helmets have similar
construction. A semi-rigid outer shell distributes the force of
impact over a wide area and a compressible foam inner layer reduces
the force upon the wearer's head.
[0010] The inner layer of single-impact helmets are typically
constructed of fused expanded polystyrene (EPS), a polymer
impregnated with a foaming agent. EPS reduces the amount of energy
that reaches the head by permanently deforming under the force of
impact. To be effective against the impact, the inner layer must be
sufficiently thick not to crush entirely throughout its thickness.
A thick inner layer, however, requires a corresponding increase in
the size of the outer shell, which increases the size and bulkiness
of the helmet.
[0011] Inner layers designed for multiple-impact helmets absorb
energy through elastic and viscoelastic deformation. To absorb
multiple successive hits, these helmets is need to rebound quickly
to return to their original shape. Materials that rebound too
quickly, however, permit some of the kinetic energy of the impact
to transfer to the wearer's head. Examples of materials with
positive rebound properties, also called elastic memory, include
foamed polyurethane, expanded polypropylene, expanded polyethylene,
and foamed vinylnitrile. Although some of these materials have
desirable rebound qualities, an inner layer constructed therefrom
must be sufficiently thick to prevent forceful impacts from
penetrating its entire thickness. The drawback of a thick foam
layer, as noted above, is the resulting bulkiness of the helmet.
Moreover, the energy absorbing properties of such materials tend to
diminish with increasing temperatures, whereas the positive rebound
properties diminish with decreasing temperatures.
[0012] Regardless of the particular material involved, the material
properties and densities of foam inner layers in helmets have
historically been selected to optimally absorb energy for impacts
that are considered severe for the particular sport or activity in
which the helmets are to be used. Foams are thus relatively
ineffective in absorbing impact energies below the severe level.
Industry safety standards currently test and certify helmet designs
based on their ability to absorb high energy impacts to ensure that
helmets protect wearers against severe head injuries, such as skull
fractures. Recent evidence has shown that lower energy impacts
result in less severe yet still damaging head injuries, typically
concussions. Current laboratory certification tests are pass/fail
tests, and are not designed to test for prevention of
concussions.
[0013] As such, testing of helmets to protect against concussions
is being developed outside the realm of existing industry standards
as the industry attempts to determine if helmets can be designed
that provide universal protection against both mild and severe
impacts. Several manufacturers are experimenting with various
permutations of laminated foams and newer materials to broaden the
range of impact energies over which the materials provide effective
energy absorption. While some progress is being made, it is
limited. This is due at least in part to the fact that foam
materials are inherently limited in their ability to absorb energy
because of their tendency to "bottom out" when compressed.
Specifically, foams can be compressed downwardly only about seventy
percent (70%) from their uncompressed thicknesses before they
become so dense and stiff that they no longer effectively absorb
impact energy. This factor is referred to as the "ride-down" point
of the foam. When compressed to the is maximum "ride-down" point, a
foam in a helmet is said to have "bottomed out", and acts
essentially as a rigid layer that transfers impact energy with
little or no absorption directly to the wearer's head.
[0014] There is thus a need in the industry for an improved helmet
construction that can reduce the risk and severity of head
injuries, including concussions, over a wide range of impact
energies, without the aforementioned disadvantages of current
helmet designs. There exists a similar need for structures that
have improved impact-absorbing properties for use in a variety of
other applications.
SUMMARY OF THE INVENTION
[0015] The present invention provides a compressible member whose
properties, configuration and construction are optimized to
maximize its impact-absorbing capabilities over a wide range of
impact energies.
[0016] In accordance with the invention, a compressible member
comprises a thin-walled enclosure defining a hollow inner chamber
containing a volume of fluid such as air. The compressible member
has at least one orifice by which fluid can vent from its inner
chamber when the member experiences an impact. Preferably, the
orifice is sized and positioned so that the compressible member
provides a rate sensitive response to impacts, i.e., the member
provides relatively low resistance to compression in response to
relatively low energy impacts and relatively high resistance to
compression in response to relatively high energy impacts. More
than one orifice may also be provided in the compressible member so
that air flows into its inner chamber following an impact at a rate
that can be selected by the designer depending on the particular
application of the member to be equal to, less than, or greater
than the rate at which air flows out of the inner chamber during
the impact.
[0017] The thin-walled enclosure of the compressible member is
preferably fabricated from blow-molded thermoplastic elastomer
material ("TPE"). TPE materials are uniquely suited for the
fabrication of the impact-absorbing, compressible members of the
invention because they can be readily and economically molded and
shaped into the desired thin-walled, hollow configuration, and
because they maintain their compressibility, stretchability and
structural integrity in use after experiencing repeated impacts.
Additionally, because they are hollow and air filled, the TPE
compressible members of the invention are capable of being
compressed to substantially greater degrees than conventional foams
of the type currently used in protective headgear, without
"bottoming out." This greater degree of "ride down" makes the TPE
compressible members of the invention effective in the absorption
of a much wider range of impact energies. Other advantages
resulting from the use of TPE materials for the compressible
members of the invention, and their higher "ride-down" factors, are
discussed in more detail below.
[0018] The compressible members of the invention may be assembled
side-by-side in a layer, and combined with one or more layers of
other materials, to form multilayer impact-absorbing shells for use
in a wide variety of applications. One particularly advantageous
embodiment of a protective shell structure comprises a thin outer
shell layer, a compressible middle layer comprised of a plurality
of the compressible members of the invention arranged in spaced
apart positions, and a thin inner layer. In response to an impact
to the outer shell layer, the outer layer deflects locally causing
the compressible members of the middle layer to compress and vent
air from their inner chambers. The inner layer is preferably
provided with one or more passageways that allow the air vented
from the compressible members to pass to the inside of the inner
layer. The outer shell layer and the inner layer are also
preferably secured to the compressible middle layer, but not
directly or rigidly to each other. This allows the outer layer to
shear or rotate relative to the inner layer and thus take up and
absorb tangential components of the impact force.
[0019] Multilayered shell structures which include one or more
compressible members of the invention can be configured and used in
the construction of a wide variety of impact-absorbing devices.
Examples disclosed include helmets, protective body pads, sports
arena padding, vehicle bumpers, dashboards and the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The above and further advantages of this invention may be
better understood by referring to the following description in
conjunction with the accompanying drawings, in which like numerals
indicate like structural elements and features in various figures.
The drawings are not necessarily to scale or relative dimension,
emphasis instead being placed upon illustrating the principles of
the invention.
[0021] FIG. 1A is a diagram illustrating an embodiment of a
compressible member of the invention having an enclosure with a
bellows-like wall construction and defining a hollow inner chamber
for holding a volume of fluid (e.g., air).
[0022] FIG. 1B is a diagram of a sequence illustrating simulated
effects of a high-energy impact to the compressible member of FIG.
1A.
[0023] FIGS. 1C and 1D are diagrams illustrating the stretching and
bending (e.g., shearing) capabilities of the compressible member of
FIG. 1A.
[0024] FIG. 1E is a diagram of the compressible member of FIG. 1A
following an impact.
[0025] FIG. 1F is a diagram illustrating the expansion of the
compressible member of FIG. 1A to its uncompressed condition after
impact force is removed.
[0026] FIG. 2 is a diagram of another embodiment of a compressible
member of the invention having a generally rectangular shape and
configuration.
[0027] FIG. 3 is a diagram of a sequence illustrating simulated
effects of an impact on another embodiment of a compressible member
of the invention having separate in-flow and outflow orifices for
the fluid contained in its inner chamber.
[0028] FIG. 4A is a partial, cross-sectional view of an embodiment
of a multilayer shell structure, which includes a layer formed of a
plurality of compressible members embodied in accordance with the
invention, configured to function as a protective helmet for a
wearer's head.
[0029] FIG. 4B is a diagram illustrating the operation of
protective shell of FIG. 4A during a direct impact.
[0030] FIG. 4C is a diagram illustrating the operation of
protective shell of FIG. 4A during a tangential impact.
[0031] FIG. 5 is a partial, cross-sectional view of an embodiment
of a multilayered shell structure, similar to that of FIG. 4A,
configured for use as a protective body pad, e.g., a shin pad.
[0032] FIG. 6 is a diagram illustrating an embodiment of a
multilayer shell structure, similar to that of FIGS. 4A and 5,
configured for use as an energy-absorbing covering for the boards
of a hockey rink.
[0033] FIG. 7 is a diagram illustrating an embodiment of a
multilayered shell structure, similar to those of FIGS. 4A, 5 and
6, configured for use as an impact-absorbing bumper on a motor
vehicle.
[0034] FIG. 8 is a diagram illustrating an embodiment of a
multilayered shell structure, similar to those of FIGS. 4A through
7, configured for use as an energy-absorbing dashboard in a
vehicle.
DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT
[0035] FIG. 1A illustrates a compressible member 50 embodied in
accordance with the present invention. The member 50 has a top
surface 120, a bottom surface 124, and a sidewall 128 that together
define a hollow inner chamber 132. The bottom surface 124 has a
small orifice 136 formed therein. When the member 50 compresses in
the general direction indicated by arrow 140, airflow 144, for
example, exits the small orifice 136. The member 50 is formed of
TPE material which, as discussed in more detail below, because of
its unique properties, optimizes the impact-absorbing properties of
the compressible member 50.
[0036] Thermoplastic elastomers or TPEs are polymer blends or
compounds, which exhibit thermoplastic characteristics that enable
shaping into a fabricated article when heated above their melting
temperature, and which possess elastomeric properties when cooled
to their designed temperature range. Accordingly, TPEs combine the
beneficial properties of plastic and rubber, that is, TPEs are
moldable and shapeable into a desired shape when heated and are
compressible and stretchable when cooled. In contrast, neither
thermoplastics nor conventional rubber alone exhibits this
combination of properties.
[0037] To achieve satisfactory purposes, conventional rubbers must
be chemically crosslinked, a process often referred to as
vulcanization. This process is slow, irreversible, and results in
the individual polymer chain being linked together by covalent
bonds that remain effective at normal processing temperatures. As a
result, vulcanized rubbers do not become fluid when heated to these
normal processing temperatures (i.e., the rubber cannot be melted).
When heated well above normal processing temperatures, vulcanized
rubbers eventually decompose, resulting in the loss of
substantially all useful properties. Thus, conventional vulcanized
rubbers cannot be formed into useful objects by processes that
involve the shaping of a molten material. Such processes include
injection molding, blow molding and extrusion, and are extensively
used to produce useful articles from thermoplastics.
[0038] Thermoplastics are generally not elastic when cooled and
conventional rubbers are not moldable using manufacturing processes
and equipment currently used for working with thermoplastics, such
as injection molding and extrusion. These processes, however, are
applicable for working with TPEs.
[0039] Most TPEs have a common feature: they are phase-separated
systems. At least one phase is hard and solid at room temperature
and another phase is elastomeric and fluid. Often the phases are
chemically bonded by block or graft polymerization. In other cases,
a fine dispersion of the phases is apparently sufficient. The hard
phase gives the TPEs their strength. Without the hard phase, the
elastomer phase would be free to flow under stress, and the
polymers would be unusable. When the hard phase is melted, or
dissolved in a solvent, flow can occur and therefore the TPE can be
processed. On cooling, or upon evaporation of the solvent, the hard
phase solidifies and the TPEs regain their strength. Thus, in one
sense, the hard phase of a TPE behaves similarly to the chemical
crosslinks in conventional vulcanized rubbers, and the process by
which the hard phase does so is often called physical crosslinking.
At the same time, the elastomer phase gives elasticity and
flexibility to the TPE.
[0040] Examples of TPEs include block copolymers containing
elastomeric blocks chemically linked to hard thermoplastic blocks,
and blends of these block copolymers with other materials. Suitable
hard thermoplastic blocks include polystyrene blocks, polyurethane
blocks, and polyester blocks. Other examples of TPEs include blends
of a hard thermoplastic with a vulcanized elastomer, in which the
vulcanized elastomer is present as a dispersion of small particles.
These latter blends are known as thermoplastic vulcanizates or
dynamic vulcanizates.
[0041] TPEs can also be manufactured with a variety of hardness
values, e.g., a soft gel or a hard 90 Shore A or greater. One
characteristic of the TPE material is its ability to return to its
original shape after the force against it removed (i.e., TPE
material is said to have memory). Other characteristics of TPE
include its resistance to tear, its receptiveness to coloring, and
its rebound resilience elasticity. Rebound resilience elasticity is
the ratio of regained energy in relation to the applied energy, and
is expressed as a percentage ranging from 0% to 100%. A perfect
energy absorber has a percentage of 0%; a perfectly elastic
material has a percentage of 100%. In general, a material with low
rebound resilience elasticity absorbs most of the applied energy
from an impacting object and retransmits little or none of that
energy. To illustrate, a steel ball that falls upon material with
low rebound resilience elasticity experiences little or no bounce;
the material absorbs the energy of the falling ball. In contrast,
the ball bounces substantially if it falls upon material with high
rebound resilience elasticity. This characteristic can influence
the behavior of the compressible member.
[0042] Another advantage of these TPEs is that their favorable
characteristics may exist over a wide range of temperatures.
Preferably, the TPE material of the compressible member 50 has a
glass-transition temperature of less than -20 degrees Fahrenheit.
The glass-transition temperature is the temperature below which the
material loses its soft and rubbery qualities. A TPE material with
an appropriate glass-transition temperature can be selected for the
compressible member 50 depending on the particular application of
the member (e.g., a glass-transition temperature of 0 degrees
Fahrenheit may be sufficient for baseball helmets, whereas a glass
transition temperature of -40 degrees Fahrenheit may be needed for
football and hockey helmets).
[0043] The size of the opening 136 in the compressible member 50 is
preferably selected to produce a rate-sensitive response to any
impact causing compression of the member 50. For instance, if the
application of force upon the member 50 is gradual or of relatively
low energy, the opening 136 permits sufficient air to pass through
so that the member 50 compresses gradually and presents little
resistance against the force. In that case, an individual may be
able to compress the member 50 manually with a moderate touch of a
hand or finger.
[0044] If, as illustrated by FIG. 1B, the application of force upon
the member 50 occurs instantaneously or is of relatively high
energy, laminar or turbulent air flows within the inner chamber
132. The size of the opening 136, which is small relative to the
volume of air moved by the force, restricts the emission of the
turbulent or laminar air from the chamber 132 and thus causes
resistance within the chamber 132. Eventually the resistance is
overcome and air flows out, and during this process, a portion of
the impact energy is also converted to heat. This variable
response, dependent upon the energy input, is termed a
rate-sensitive or a non-linear response.
[0045] A further important advantage of the compressible member 50
is that it can be compressed ninety percent (90%) or more from its
uncompressed thickness before "bottoming out", i.e., before the top
wall of TPE material comes in contact with the bottom wall of TPE
material. This increased "ride-down" factor compared to
conventional foams, which have ride-down factors of only about 70%,
increases the distance over which impacts are effectively absorbed
and, as a result, decreases the force trans-ferred through the
compressible member 50 proportionately to this increased distance.
Even when the compressible member 50 "bottoms out", a thickness of
TPE material (equal to twice the wall thickness) remains, which,
because of its compressibility, provides further energy
absorption.
[0046] Additionally, the geometry of the compressible member 50,
the stiffness and elasticity of the TPE material used for its
enclosure, and the venting of the member 50 can all be adjusted and
optimized to provide a "softer landing" than conventional foams
across a broad range of impact energy levels. Force/time curves for
foams are bell-shaped due to the increased stiffness of foams as
they are compressed which results in increasing forces with severe
peaks. The shape of the force/time curve for foams is similar
regardless of the amount of ride-down, which is dependent on the
energy of the impact. For low energy impacts, the ride-down
distance of foams is low and can result in concussions, even at
relatively low impact energies, especially with EPS foams.
[0047] The compressible member 50 of the invention, on the other
hand, can be engineered to allow optimal ride down for a wide range
of impact energies and also to "shape" the rate at which the forces
increase during the impact. This "shaping" of the force/time curve
is accomplished by managing the air pressure in the inner chamber
of the member 50 for various impact energies, something foams
cannot do. The result is a flatter and broader force/time curve for
the compressible member 50 which reduces the force of impact. This
broader, flatter curve in essence demonstrates a "soft
landing".
[0048] This technology allows for the manipulation of multiple
engineering parameters, such as material properties, chamber
geometry, chamber wall thickness, and relative configurations of
outflow(s) and inflow(s). Careful calibration of the many design
parameters will allow those skilled in the art to determine the
optimum combination based on the particular application to which
the member 50 is to be put.
[0049] In addition to providing this rate-sensitive response, the
compressible member 50 can also stretch and bend during tangential
impact, as illustrated by FIG. 1C and FIG. 1D. This allows the
compressible member 50 to shear in response to the tangential
impacts and absorb rotational forces as well as direct forces
applied normal to the top surface 120 of the member 50.
[0050] FIG. 1E shows the compressible member 50 following an
impact. Because of its resilient nature, the tendency of the member
50 is to return to its uncompressed shape. Accordingly, after the
impact force is removed from the compressible member 50, it expands
in the direction indicated by arrow 146, consequently drawing air
in through the opening 136 as indicated by arrows 148. FIG. 1F
illustrates a simulated sequence of expansion of a rate-sensitive
compressible member 50, as the impact force is removed.
[0051] FIG. 2 shows a cross-section of another embodiment of a
rate-sensitive compressible member 150 that is generally
rectangular in shape (i.e., a strip). The member 150 has a top
surface 160, a bottom surface 164, sidewalls 168-1, 168-2
(generally, 168), and a hollow inner chamber 172. Each sidewall 168
has a respective small opening 176-1, 176-2 (generally, 176) formed
therein. (Practice of the invention can be achieved with only one
of the sidewalls 168 having an opening). When the member 150
compresses generally in the direction indicated by arrow 180,
airflows 184 exit the small openings 176. This embodiment
illustrates that a variety of shapes, for example, disc-shaped,
cylindrical, and pyramidal, and the like, can be used to implement
rate-sensitive compressible members of the invention capable of
absorbing impact energy.
[0052] FIG. 3 diagrammatically illustrates another version of a
compressible member 250 embodied in accordance with the invention.
The compressible member 250 differs from the prior two embodiments
in that it includes separate orifices for the inflow and outflow,
respectively, of air relative to its inner chamber. More
specifically, the compressible member 250 includes a plurality of
outflow orifices, in the form of thin slits 254 in the wall of its
enclosure 252, spaced about the circumference of the enclosure 252.
The compressible member 250 also includes an inflow orifice, which
includes a one-way flap valve 256, located at the bottom of the
enclosure 252.
[0053] As the sequence of FIG. 3 illustrates, moving from left to
right in the figure, upon impact, the one way flap valve 256 is
forced closed and air is forced out of the inner chamber of the
compressible member 250 through the thin slits 254. Upon removal of
the force, the one-way flap valve 256 opens and air returns quickly
to the inner chamber of the compressible member 250 through the
opening of the valve.
[0054] To further enhance the "rate-sensitive" response of the
compressible member 250 of this embodiment, the outflow slits 254
are elastic, being formed directly in the TPE material of the wall
of the enclosure 252. Because of this elasticity, the slits 254
provide some resistance to opening and to the escape of the air in
the inner chamber during the impact, and close resiliently and
quickly following the impact. The slits 254 are also preferably
significantly smaller in diameter that the inflow opening of the
one-way flap valve 256. As a result, the member 250 provides a
greater degree of resistance to compression and collapse depending
upon the energy level of the impact force, yet will return quickly
to its uncompressed condition upon removal of the force, ready to
absorb additional impacts.
[0055] FIG. 4A is a partial cross-sectional view of an embodiment
of a multilayer shell structure 230 which includes a plurality of
the rate-sensitive compressible members 50 (FIG. 1A) disposed
therein, configured as a protective helmet 200. In this particular
embodiment shown, the compressible members 50 are spaced from one
another and sandwiched between an outer layer 220 and an inner
layer 228. An internal foam liner 232 of conventional design may be
disposed between the inner layer 228 and the wearer's head.
[0056] In the shell structure 230 of FIG. 4A, the orifice 136 of
each rate-sensitive compressible member 50 preferably aligns with
an opening (not shown) in the surface of the inner layer 228 and
through any internal liner 232 so that expelled or inhaled air can
pass into the interior of the shell structure 230. Similarly, such
openings 136 can be on the sides of the compressible members 50,
allowing the release and return of air through the interstitial
region of the shell structure 230 between the outer and inner
layers 220 and 228.
[0057] Those desiring further details of the construction of a
shell structure such as shell structure 230, and its configuration
as a protective helmet, are referred to my copending U.S. patent
application Ser. No. 11/059,427, filed Feb. 16, 2005, and my
related application filed concurrently herewith, titled
"EnergyAbsorbing Inner Liners For Use With Protective Headgear"
(Cesari and McKenna, LLP Docket No. 104208-0019), which, as noted
above, are incorporated by reference herein.
[0058] Those skilled in the art will appreciate that other
embodiments of the compressible member, such as the members 150 and
250 shown above, can be substituted for the compressible members 50
in the shell structure 230 of FIG. 4A, and that two or more types
or sizes of compressible members can be combined therein. Those
skilled in the art will also appreciate that modifications can be
made to the shell structure 230 without departing from the scope of
the invention. For example, the compressible members 50 may be
secured to a single layer, either on their inside or outside,
instead of being sandwiched between two layers as shown in FIG. 4A.
Additionally, the compressible members 50, instead of being
separate from one another, could be interconnected by a thin web of
TPE material to form a sheet-like middle layer. The connecting web
material could also include internal passageways that communicate
with the inner chambers of adjacent ones of the compressible
members 50, so that, during an impact, air passes from one chamber
or member 50 to another, in addition to venting from the chambers,
spreading the impact force among several members 50.
[0059] FIG. 4B illustrates an exemplary simulated operation of the
shell structure 230, with rate-sensitive compressible members 50,
undergoing a direct impact from an object 236. In this example, the
shell structure 230 operates to reduce linear-acceleration of the
wearer's head 234. When the object 236 strikes the outer layer, the
members 50 directly beneath the outer layer 220 at the point of
impact compress. The compression of the shell structure 230 also
causes air to exit the members 50 (arrows 238) and enter the
interior of the shell structure 230 through the openings in the
members 50 and in the inner layer 228.
[0060] FIG. 4C illustrates an exemplary simulated operation of the
shell structure 230, with rate-sensitive compressible members 50,
undergoing a tangential impact from an object 236. In this example,
the shell structure 230 operates to reduce rotational acceleration
of the wearer's head 234. When struck by an object tangentially,
the outer layer 220 shears with respect to the inner layer 228 in a
direction of motion of the object, as illustrated by arrows 240.
Members 50 at the point of impact compress to some extent and shear
with the outer layer 220. As with the example of FIG. 4B, the
compression causes air to exit the members 50 and to enter the
interior of the headgear. The combined effects of the shearing
motion of the outer layer 220 and members 50, the rate-sensitive
and energy-absorbing compression of the members 50, and the release
of air into the interior of the headgear operate to reduce the
rotational forces reaching the wearer's head 234.
[0061] The layered construction of the invention can be likewise
used to construct a variety of types of protective headgear
including, but not limited to, safety helmets, motorcycle helmets,
bicycle helmets, ski helmets, lacrosse helmets, hockey helmets, and
football helmets, batting helmets for baseball and softball,
headgear for rock and mountain climbers, and headgear for boxers.
Other applications can include helmets used on construction sites,
in defense and military applications, and for underground
activities.
[0062] Although the foregoing description focuses primarily on
protective headgear, it is to be understood that the compressible
members of the invention can be used in other types of equipment
used for sports activities or other applications.
[0063] By way of example, FIG. 5 illustrates the shell structure
230 configured as a shin pad which may be removably fastened by any
suitable means e.g., elastic straps, to the lower leg of a wearer.
Those skilled in the art will appreciate that the shell structure
230 may be similarly configured as a face mask, elbow pad, shoulder
pads, chest protector or the like, or as a protective body pad for
other sports/activities such as "extreme" and other outdoor sports,
motorcross, car racing, and the like.
[0064] FIG. 6 illustrates a shell structure 230', similar to, but
fabricated in larger scale and dimension than, the shell structure
230 previously described, as an impactabsorbing covering for
application to the boards of a hockey rink. A similar shell
structure 230' could be used as an impact-absorbing covering for
basketball gymnasium walls, racket ball walls, indoor soccer or
football arenas, and other structures which enclose an athletic
event.
[0065] FIGS. 7 and 8 illustrate still another version of a shell
structure 230'', similar to but larger than the shell structure 230
previously described, configured as part of a vehicle bumper and
dashboard, respectively. Other similar applications of the shell
structure 230'' include vehicle decking, highway barriers and the
like.
[0066] While the invention has been shown and described with
reference to specific preferred embodiments, it should be
understood by those skilled in the art that various changes in form
and detail may be made therein without departing from the spirit
and scope of the invention as defined by the following claims.
* * * * *