U.S. patent application number 12/296843 was filed with the patent office on 2009-10-29 for fluid safety liner.
This patent application is currently assigned to MASSACHUSETTS INSTITUTE OF TECHNOLOGY. Invention is credited to Nicholas Chan, Jason Ruchelsman, Laurence Young.
Application Number | 20090265839 12/296843 |
Document ID | / |
Family ID | 39312995 |
Filed Date | 2009-10-29 |
United States Patent
Application |
20090265839 |
Kind Code |
A1 |
Young; Laurence ; et
al. |
October 29, 2009 |
Fluid Safety Liner
Abstract
A fluid safety liner includes a liner of closed-cell foam that
uses a series of channels and reservoirs to spread forces and
distribute fluid contained within the liner throughout different
areas of the liner. The liner is useable in protective gear such as
a helmet and has a shape that conforms to the area of protection.
The channel and reservoir system generally includes a mesh of
coupled channels and reservoirs in the closed-cell foam. The
channel and reservoir system also generally includes an
incompressible fluid movable throughout the system for
redistributing pressure and absorbing the force of any impact
through viscous flow. The reduction in peak force and lengthening
of the duration of the force reduces the biomechanical severity
(e.g. HIC, Head Injury Criterion) of a blow to the protective
gear.
Inventors: |
Young; Laurence; (Waterville
Valley, NH) ; Chan; Nicholas; (Boston, MA) ;
Ruchelsman; Jason; (New York, NJ) |
Correspondence
Address: |
Sunstein Kann Murphy & Timbers LLP
125 SUMMER STREET
BOSTON
MA
02110-1618
US
|
Assignee: |
MASSACHUSETTS INSTITUTE OF
TECHNOLOGY
Cambridge
MA
|
Family ID: |
39312995 |
Appl. No.: |
12/296843 |
Filed: |
April 12, 2007 |
PCT Filed: |
April 12, 2007 |
PCT NO: |
PCT/US2007/066518 |
371 Date: |
March 16, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60792287 |
Apr 13, 2006 |
|
|
|
Current U.S.
Class: |
2/413 |
Current CPC
Class: |
A41D 13/015 20130101;
A42B 3/121 20130101 |
Class at
Publication: |
2/413 |
International
Class: |
A42B 3/06 20060101
A42B003/06 |
Claims
1. A device, wearable on the body, for protecting a body part
against a physical blow, the device comprising: a closed-cell foam
member, such member having an inner surface conforming generally to
an outer surface of the body part, such member including a
plurality of conduits and such member being deformable; a fluid
disposed in the conduits; so that when the foam member experiences
a blow at a location, the blow triggers a pressure wave in the
fluid and flow of fluid in the conduits away from that location in
such a manner as to absorb energy from the blow and to redistribute
force from the blow away from the location.
2. A device according to claim 1, wherein the closed-cell foam
member is a liner for a helmet.
3. A device according to any of claims 1 and 2, wherein the device
includes at least four conduits and such conduits are in
communication with each other to form a mesh.
4. A device according to any of claims 1 through 3, wherein the
fluid is substantially incompressible.
5. A device, wearable on the body, for protecting a body part
against a physical blow, the device comprising: a closed-cell foam
member, such member having an inner surface conforming generally to
an outer surface of the body part, such member including at least
one fluid channel; wherein the at least one fluid channel is in
communication with at least two reservoirs formed in the
closed-cell foam member; a liquid disposed in the at least one
channel and in the reservoirs; so that when the foam member
experiences a blow in the vicinity of one of the reservoirs, the
blow triggers a pressure wave in the fluid and flow of fluid in
that onc of the reservoirs through the at least one channel to
another one of the reservoirs in such a manner as to absorb energy
from the blow and to redistribute force from the blow away from the
vicinity.
6. A device according to claim 5, wherein the closed-cell foam
member is a liner for a helmet.
7. A device according to any of claims 5 and 6, wherein such member
includes at least four channels, at least four reservoirs are
formed in the member, and the reservoirs are coupled to one another
via the channels so as to form a mesh.
8. A device according to claim 5, wherein the fluid is
substantially incompressible.
9. A device according to claim 5, wherein the fluid is a
combination of incompressible fluid and compressible fluid
10. A device according to claim 5, wherein the fluid is a shear
thickening fluid.
11. A device according to claim 5, wherein the fluid is a shear
thinning fluid.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority from U.S.
provisional application No. 60/792,287 filed Apr. 13, 2006,
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to safety liners that
incorporate the use of fluids to disperse the force of an impact,
in particular the use of fluid safety liners for protection of the
head and other body parts.
BACKGROUND ART
[0003] It is known in the prior art to provide protective helmets
that use primarily foam to cushion an impact. It is also known in
the art to use fluids in the design of the helmet to absorb the
energy of the impact. U.S. Pat. No. 5,815,846 to Calonge discloses
a helmet assembly using a combination of a gas and a fluid
(including a generally viscous gel) for impact distribution and
dampening. U.S. Pat. No. 3,609,764 to Morgan discloses the use of
interconnected flexible chambers that can increase and decrease in
size and transfer fluid from a first chamber to an adjacent second
chamber when an impact force is applied.
SUMMARY OF THE INVENTION
[0004] In a first embodiment of the invention there is provided a
device, wearable on the body, for protecting a body part against a
physical blow having a closed-cell foam member and fluid disposed
within. The closed-cell foam member has an inner surface that
conforms generally to the outer surface of a body part. The member
has a plurality of conduits formed within where fluid is located.
Upon receipt of a blow at a location, the blow will cause the fluid
located in the conduits within the member to move away from that
location to absorb energy from the blow and to redistribute the
force from the blow away from the location.
[0005] In a related embodiment the closed-cell foam member is a
liner for a helmet.
[0006] In another embodiment the closed-cell foam member has at
least 4 conduits formed within that are coupled in such a way as to
form a mesh.
[0007] In a related embodiment the conduits of the closed-cell foam
member contain a fluid that is substantially incompressible.
[0008] In another embodiment there is provided a device wearable on
the body for protecting a body part against a physical blow having
a closed-cell foam member and at least one fluid channel in
communication with at least two reservoirs within the member. The
closed-cell foam member has a surface that conforms generally to an
outer surface of the body part. The member has fluid within the
channel and reservoirs that upon impact is urged away from the
reservoir in the vicinity of the blow through the channel to
another reservoir further from the vicinity of the blow to absorb
energy and redistribute force from the blow.
[0009] In a related embodiment the closed-cell member is a liner
for a helmet.
[0010] In a related embodiment the closed-cell member includes at
least four channels and at least four reservoirs formed in the
member. In the member the reservoirs are coupled to one another via
the channels so as to form a mesh.
[0011] In a related embodiment the fluid within the member is
substantially incompressible.
[0012] In another related embodiment the fluid within the member is
a combination of incompressible fluid and compressible fluid.
[0013] In yet another related embodiment the fluid within the
member is a shear-thickening fluid.
[0014] In yet another related embodiment the fluid within the
member is a shear-thinning fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The foregoing features of the invention will be more readily
understood by reference to the following detailed description,
taken with reference to the accompanying drawings, in which:
[0016] FIG. 1 is a schematic profile illustrating distribution of
force and pressurc, experienced on the head of a subject wearing a
conventional helmet, upon impact of a blow to the helmet.
[0017] FIG. 2 is a schematic profile illustrating distribution of
force and pressure, experienced on the head of a subject wearing a
helmet, upon impact of a blow to the helmet, when the helmet
incorporates a liner in accordance with an embodiment of the
present invention.
[0018] FIG. 3 is a perspective view of an embodiment of the present
invention incorporating a plurality of reservoirs in a liner of
closed-cell foam, wherein the relative locations of the reservoirs
are depicted.
[0019] FIG. 4 is a cross section of the liner of FIG. 3.
[0020] FIG. 5 is a perspective schematic view of the liner of FIG.
3, having the same orientation as that of FIG. 3, illustrating the
outer surface of the liner in relation to the reservoirs disposed
therein.
[0021] FIG. 6 is another perspective view of the liner of FIG. 3,
again having the same orientation as that of FIG. 3, illustrating
the outer surface of the liner.
[0022] FIG. 7 is a perspective view of an embodiment of the present
invention incorporating a plurality of conduits in a liner of
closed-cell foam, wherein the relative locations of the conduits
are depicted.
[0023] FIG. 8 is a perspective schematic view of the liner of FIG.
7, having the same orientation as that of FIG. 7, illustrating the
outer surface of the liner in relation to the conduits disposed
therein.
[0024] FIG. 9 is a graph illustrating the effects a fluid liner has
on the force profile over time due to an impact as compared to the
effects a conventional foam liner has on the force profile over
time due to an impact.
[0025] FIGS. 10a and 10b are graphs illustrating the pressure
distribution over the corresponding liners area
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0026] Definitions. As used in this description and the
accompanying claims, the following terms shall have the meanings
indicated, unless the context otherwise requires:
[0027] A "mesh" is a network of conduits within which fluid is
displaced on receipt of a blow in such a manner that force
associated with impact of the blow is distributed away from the
vicinity of the blow and energy associated with impact of the blow
is dissipated.
[0028] A "conduit" is a volumetric region in a deformable medium
for holding fluid and conveying fluid. A conduit may serve as a
channel for conveying fluid and in addition may serve as a
reservoir of variable volume for fluid. Accordingly, in the course
of deformation of the medium at a given location of a conduit, the
conduit expels fluid from the given location. However, since the
medium is deformable, the conduit conveys fluid away from the given
location, and conduit portions located away from the given location
will expand to receive fluid displaced as a result of the
deformation.
[0029] A "reservoir" is a conduit in a deformable medium for
holding, supplying, or receiving fluid.
[0030] A "channel" is a conduit in a deformable medium for
conveying fluid.
[0031] FIG. 1 is a schematic profile illustrating a prior art
distribution of force and pressure, experienced on the head of a
subject wearing a conventional helmet, upon impact of a blow to the
helmet. In FIG. 1, the force of the blow is represented by vector
11. The blow is imparted to prior art helmet 12, with which is
associated a prior art liner 14. The force 11 is transmitted
through the helmet 12 and through the liner 14 to produce force and
pressure on the head 13 of the subject. The magnitude of the force
is at a peak at the point of impact, and diminishes as distance
from the point of impact increases. The distribution of force in a
direction normal to the head is illustrated by vectors 15. It can
be seen that, while the combination of helmet 12 and liner 14
achieves some distribution of force, nevertheless the distribution
of force is highly localized.
[0032] FIG. 2 is a schematic profile illustrating distribution of
force and pressure, experienced on the head of a subject wearing a
helmet, upon impact of a blow to the helmet, when the helmet
incorporates a liner in accordance with an embodiment of the
present invention. Similarly, here the force of the blow is
represented by vector 11. The blow is imparted to helmet 12, with
which is associated a liner 21 in accordance with an embodiment of
the present invention. Prior to the blow, the liner has a profile
indicated by dashed line contour 22. The force 11 is transmitted
through the helmet 12 and through the liner 21 to produce pressure
on the head 13 of the subject. The liner 21 includes a number of
conduits in which fluid is disposed. The blow causes fluid in the
liner to flow away from the vicinity of the blow and the liner to
deform into the shape having the profile indicated by solid line
contour 23. The distribution of forces, in a direction normal to
the head caused by the blow as transmitted by the helmet and liner
is illustrated by vectors 25. Although here as in FIG. 1, the
magnitude of the force is at a peak at the point of impact, and
diminishes as distance from the point of impact increases, the
magnitude of the force at the point of impact is here reduced and
spread over a larger region. It can be seen that the combination of
helmet 12 and liner 21 achieve a distribution of force over a
greater area, in such a manner that the force in the vicinity of
the blow has been reduced in comparison to the force in the
vicinity of the blow in the case of the prior art embodiment
illustrated in FIG. 1. In other words, the liner 21 has the effect,
among other things, of distributing force of the blow away from the
region of impact.
[0033] The liner responds to a blow by deformation triggering the
flow of fluid within and also by causing propagation of a pressure
wave through the fluid. In combination these processes cause
distribution of force over a larger region compared to the prior
art and also involves absorption of energy. Of course the liner
material, itself, even independent of the pressure of fluid,
accounts for some absorption of force and some absorption of
energy.
[0034] It can also be seen that the blow in the embodiment of FIG.
2 has caused deformation of the liner 21. As will be described in
further detail below, the liner contains fluid that is displaced as
a result of the blow and propagates a pressure wave as a result of
the blow. As previously discussed the processes are responsible in
part for the deformation and also serve to absorb some energy from
the blow.
[0035] In general, we can describe handling of the impact of the
blow by this equation:
.intg..sub.APdA=F.sub.B (1),
where F.sub.B is the force of the blow, P is the local pressure at
a given location of the head, and A is the area of the region,
projected onto a plane normal to the force of the blow, over which
the pressure is experienced.
[0036] FIG. 3 is a perspective view of an embodiment of the present
invention incorporating a plurality of reservoirs in a liner of
closed-cell foam, wherein the relative locations of the reservoirs
are depicted. In FIG. 3, the peripheral reservoirs 33 are shown in
their relative locations along the lower outer region of liner 21.
The reservoirs 33 and 34 are coupled by channels 35 to form a mesh.
(For convenience of illustration, the channels and reservoirs are
not shown to scale.) The channels, for example, are here shown as
lines, whereas in fact, the channels have a cross sectional area
sufficient to convey fluid between reservoirs.
[0037] Although we have distinguished between reservoirs and
channels, both reservoirs and channels are disposed in closed-cell
foam, a deformable medium, so that the functions of reservoirs and
of channels overlap one another--namely, the reservoirs serve also
to convey fluid and the channels serve also to hold fluid. In this
respect, we say that the reservoirs and the channels are both
"conduits" as that term is defined above.
[0038] FIG. 3 also shows the interior reservoirs 34 arranged in an
overarching pattern relative to peripheral reservoirs 33. On
receipt of a blow, fluid flows through channels 35, causing a
redistribution of fluid in the liner. As discussed previously, the
fluid flow can absorb energy from the blow.
[0039] The closed-cell foam of the liner may be made of a wide
range of materials. Indeed, various types of closed-cell foam may
be employed in various embodiments of the present invention. Some
types of closed-cell foam contemplated include EPS (Expanded
Polystyrene) and EPP (Expanded Propylene). EPS is one-use only
(permanently deforms) whereas EPP may be reusable, at least to some
extent. In the latter category, is Cell-Flex NX210, available from
Der-Tex Corp, Saco, Me. Additional materials of this type are
available from Foam Fabricators Inc., Scottsdale, Ariz. Desirable
performance characteristics of closed-cell foam for the liner are
elastic deformability on receipt of a blow. Such characteristics
enable the liner to experience local deformation on receipt of the
blow to cause movement of fluid away from the area of impact, and
also expansion of conduits in the liner in regions away from the
area of impact. Also desirably in many cases, after impact the
liner and conduits in the liner return generally to their original
shapes and pressure of the fluid returns to pre-impact levels.
Materials providing elastic deformation may be desirable in many
cases in comparison to those providing plastic or permanent
deformation because the former materials provide an opportunity for
reuse of the liner.
[0040] A range of fluids may be employed in various embodiments of
the present invention. The fluid may, for example, be
non-Newtonian, including shear-thickening fluids and shear-thinning
fluids. In some embodiments, the fluid is incompressible. Suitable
fluids include those currently used in existing knee pads, for
example, those manufactured by Fluid Forms, Inc., Boulder, Colo.,
under the 1002 Patella T trademark. Suitable fluids include liquid
silicone oil (a polymerized siloxane), a product currently used,
among other things, for impact absorption in shoes. Silicone oil is
available in a wide range of viscosities from various suppliers,
including Clearco Products, Bensalem, Pa. A silicone oil can be
chosen to provide a desired viscosity and desired fluid flow
characteristics for use in embodiments of the present invention. In
further embodiments, one of the fluids employed may include gas or
a substance that has more than one phase, such as a substance that
is in a gas, liquid, and/or solid phase.
[0041] FIG. 4 is a cross section of the liner of FIG. 3. In this
cross section view of liner 21 reservoirs 33 and 34 are located
within the closed-cell foam. Reservoirs 33 and 34 are in the same
configuration in FIG. 4 as was illustrated in FIG. 3. In FIG. 4 the
closed-cell foam inner surface 41 that conforms generally to an
outer surface of the body part can be seen. Reservoirs 33 and 34
are in the same configuration in FIG. 4 as was illustrated in FIG.
3. The reservoirs 33 and 34 are coupled by channels 35 to form a
mesh as was illustrated in FIG. 3.
[0042] FIG. 5 is a perspective schematic view of the liner of FIG.
3, having the same orientation as that of FIG. 3, illustrating the
outer surface of the liner in relation to the reservoirs disposed
therein. Reservoirs 33 and 34 are in the same configuration in FIG.
5. as was illustrated in FIG. 3. The reservoirs 33 and 34 are
coupled by channels 35 to form a mesh as was illustrated in FIG.
3.
[0043] FIG. 6 is another perspective view of the liner of FIG. 3,
again having the same orientation as that of FIG. 3, illustrating
the outer surface of the liner. The channels 35 illustrated in FIG.
3. are shown here, configured in a mesh without being coupled to
reservoirs 33 and 34.
[0044] FIG. 7 is a perspective view of an embodiment of the present
invention incorporating a plurality of conduits in a liner of
closed-cell foam, wherein the relative locations of the conduits
are depicted. On receipt of a blow, fluid flows through conduits
71, causing a redistribution of fluid in the liner. The conduits in
the general embodiment must be in a deformable medium. In addition
to absorption of energy caused by fluid flow, the flow of fluid
throughout the liner also serves to redistribute the fluid for the
purpose of expanding the area of closed-cell foam over which the
net pressure is applied, thereby reducing the maximum magnitude of
pressure experienced at a particular location.
[0045] The conduits 71 may have various shapes to meet the needs of
the desired flow pattern and viscosity characteristics associated
with the fluid employed. The conduits may include orifices,
constrictions, baffles, and or valves. As FIGS. 1-8 indicate, the
conduit path need not be in a straight line, and may be contoured
to provide desired force distribution and energy absorption.
[0046] FIG. 8 is a perspective schematic view of the liner of FIG.
7, having the same orientation as that of FIG. 7, illustrating the
outer surface of the liner in relation to the conduits 71 disposed
therein.
[0047] FIG. 9 is a graph from a study conducted to illustrate the
effects a fluid-filled liner has on attenuation of peak forces
associated with a blow. Tn the study a fluid liner and a foam liner
were constructed. The foam liner used conventional ski helmet foam
found supplied from Der-Tex Corp. Saco, Me. The fluid liner was
made from a slightly elastic and waterproof fabric used in the
design of army tents. Each of the liners were wrapped around a
steel cylinder and set up for a drop test in an Instron Dynatup
9250 drop tester. Each of the liners was dropped from a height of 1
meter and the impact force and velocity were measured as a function
of time through the use of strain gauges and light sensors in the
Dynatup machine. The pressure distribution was also recorded
through the use of Pressurex strips (thin sheets that turn varying
densities of red when pressure is applied). Curve 91 illustrates
the magnitude of the force felt by the foam liner over time. Curve
93 illustrates the magnitude of the force felt by the fluid liner
over time. The peak force 94 experienced by the fluid liner is
substantially lower than the peak force 92 experienced by the foam
liner. The time of impact for the fluid liner was almost twice as
long as the impact time for the foam liner. The fluid liner also
experienced a more uniformly applied force over its impact time as
opposed to the foam liner that experienced a series of force peaks
and dips during its impact.
[0048] FIGS. 10a and 10b are graphs from the same study discussed
in connection with FIG. 9. FIGS. 10a and 10b illustrate the
pressure distribution that results upon impact of a liner. FIG. 10a
represents the fluid liner. FIG. 10b represents the foam liner.
Impact forces are distributed over a larger area in the fluid liner
as compared to the foam liner. In particular, it can be seen in
FIG. 10a that a maximum pressure of 100 PSI (pounds-per square
inch) is experienced by the fluid liner, while FIG. 10b shows that
a maximum pressure of 115 PSI is experienced by the foam liner.
* * * * *