U.S. patent number 3,849,801 [Application Number 05/316,799] was granted by the patent office on 1974-11-26 for protective gear with hydraulic liner.
This patent grant is currently assigned to Medalist Industries, Inc.. Invention is credited to M. C. Holt, Walter F. Tomczak.
United States Patent |
3,849,801 |
Holt , et al. |
November 26, 1974 |
PROTECTIVE GEAR WITH HYDRAULIC LINER
Abstract
Protective gear such as head gear for use in sports, industry,
and the military, etc. includes a one-piece molded protective outer
shell such as a helmet shell with a hydraulic energy absorbing
liner which has an array of interconnected compressible vinyl
walled compartments arranged around a central crown compartment
with shock and energy dissipating fluid in the interconnected
compartments. Each of the compartments is provided with a porous
insert or surge mitigator of open-celled foam, which throttles
fluid flow within the compartments as the compartments are
compressed and deformed upon impact, thus to absorb or dissipate
energy. The porous inserts also prevent sloshing of fluid and
retain some fluid in the compartments at all times, preventing
complete collapse of one or more compartments during impact. In
preferred embodiments, the fluid includes hydraulic liquid.
Inventors: |
Holt; M. C. (Leesburg, FL),
Tomczak; Walter F. (Leesburg, FL) |
Assignee: |
Medalist Industries, Inc.
(Milwaukee, WI)
|
Family
ID: |
23230737 |
Appl.
No.: |
05/316,799 |
Filed: |
December 20, 1972 |
Current U.S.
Class: |
2/413 |
Current CPC
Class: |
A42B
3/121 (20130101) |
Current International
Class: |
A42B
3/04 (20060101); A42B 3/12 (20060101); A42b
003/02 () |
Field of
Search: |
;2/3R,2,6,7
;267/113,117,152,153 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schroeder; Werner H.
Assistant Examiner: Chan; Wai M.
Attorney, Agent or Firm: House, Jr.; Joseph P.
Claims
We claim:
1. Protective gear comprising an outer shall, a hydraulic liner for
said shell having an array of interconnected collapsible hydraulic
fluid containing compartments, hydraulic fluid in said
compartments, the interconnection of one compartment with another
allowing displacement of hydraulic fluid from a deformed
compartment to other compartments in said array, deformable highly
porous hydraulic fluid surge mitigating means having substantial
void space in said compartments for throttling hydraulic fluid flow
within a compartment and between said interconnected compartments
caused by deformation of said compartment and to dissipate and
absorb the energy causing the deformation and to retain hydraulic
fluid in the deformed compartment regardless of the displacement of
some hydraulic fluid to other compartments.
2. Protective gear in accordance with claim 1 wherein said surge
mitigating means comprises reticulated inserts providing a
multiplicity of hydraulic fluid passages and obstructions to
hydraulic fluid flow which causes a pressure drop during movement
of hydraulic fluid within the insert.
3. Protective gear in accordance with claim 2 wherein said porous
insert is constructed of open-celled foam.
4. Protective gear in accordance with claim 3 wherein said foam is
a polyurethane resin.
5. Protective gear in accordance with claim 1 wherein said array
includes forward, rear and side arrays of compartments arranged
around a crown compartment and means defining hydraulic fluid
passages interconnecting each of said compartments in each of said
arrays and interconnecting each array with said crown
compartment.
6. Protective gear in accordance with claim 1 in which said
compartments also contain air.
7. Protective gear in accordance with claim 1 in which the fluid
volume occupied by the hydraulic fluid is in excess of one-half of
the total available space within said array.
8. Protective gear in accordance with claim 1 wherein said
hydraulic fluid surge mitigating means substantially occupies the
volume of said compartment.
9. Protective gear in accordance with claim 1 including an
intermediate sizing liner between said hydraulic liner and said
shell.
10. Protective head gear comprising an outer covering, an energy
absorbing liner for said covering including an array of fluid
compartments, hydraulic fluid in said compartments, fluid passages
interconnecting adjacent compartments to allow displacement of
hydraulic fluid from a deformed compartment to other compartments
in said array and deformable highly porous means having substantial
void space occupying the major portion of the volume of each of
said compartments to provide a controlled resistance to movement of
hydraulic fluid within said compartment and between said
compartments and to retain a quantity of hydraulic fluid in said
compartments during use of the head gear nothwithstanding
substantial deformation of a compartment due to impact and the
tendency of hydraulic fluid to be displaced from said deformed
compartment.
11. Protective head gear in accordance with claim 10 in which said
fluid compartments also contain air.
12. Protective head gear in accordance with claim 11 in which the
air comprises less than one-half and the hydraulic fluid comprises
in excess of one-half of the total available space within said
compartments.
13. Protective head gear comprising an outer shell shaped to
receive a wearer's head, an energy absorbing liner for said shell
comprising an array of interconnected deformable compartments, the
interconnection of one compartment with another allowing
displacement of hydraulic fluid from a deformed compartment to
other compartments in said array, hydraulic fluid in said
compartments, and deformable highly porous resilient hydraulic
fluid surge mitigating means having substantial void space
materially filling the space within said compartments, said means
providing a plurality of fluid orifices and flow obstructions to
cause energy dissipating pressure losses upon movement of the
hydraulic fluid through said orifices and around said obstructions
as a result of deformation of said compartments, said surge
mitigating means retaining hydraulic fluid in a deformed
compartment regardless of the displacement of some hydraulic fluid
to other compartments.
14. Protective head gear in accordance with claim 10 in which said
array includes compartments at opposite sides of the wearer's head,
whereby hydraulic fluid displaced from a deformed compartment at
one side of the wearer's head will migrate through said fluid
passages to a compartment at the other side of the wearer's
head.
15. Protective head gear in accordance with claim 13 in which said
array includes compartments at opposite sides of the wearer's head,
whereby hydraulic fluid displaced from a deformed compartment at
one side of the wearer's head will migrate through said fluid
passages to a compartment at the other side of the wearer's head.
Description
BACKGROUND OF THE INVENTION
Various types of impact absorbing safety head gear have been
developed in which hydraulic fluid filled compartments are employed
to dissipate the energy of an impact. Simpson U.S. Pat. No.
3,039,109, Cade et al., U.S. Pat. No. 3,600,714, and Morgan U.S.
Pat. No. 3,609,764 are illustrative of safety helmets which employ
innerconnected cells or compartments arranged around the interior
of the helmet with a contained hydraulic fluid. Upon impact, the
fluid in the liners of these helmets is squeezed from a deformed or
compressed compartment into an adjacent compartment. Relatively
small diameter innerconnecting passageways between the compartments
obstruct fluid flow between the compartments and cause a drop in
pressure of the fluid as it is squeezed through the passageways,
resulting in performance of work and absorption of energy.
The fluid cell liners typified by the foregoing patents have
certain disadvantages which include the danger of complete loss of
fluid from one or more compartments caused by a rupture of one cell
or compartment and the resulting complete collapse of the
compartment. The bottoming or complete collapse of a cell can
result in loss of protection in the zone of the collapsed cell and
consequent risk of injury to the wearer of the head gear.
Other problems inhering in prior art head gear with hydraulic fluid
liners include noticeable and distracting fluid noises caused by
sloshing of the fluid in the cells, unequal distribution of fluid
in the cells caused by gravity migration of fluid, excessive head
gear weight caused by complete filling of the cells with liquid,
etc.
SUMMARY OF INVENTION
The difficulties and problems associated with prior art helmets
having a hydraulic fluid energy absorbing system with a plurality
of interconnected cells are avoided in the present invention by the
use of surge mitigators in the form of reticulated foam or like
inserts which materially fill the space enclosed within the
interconnected liquid containing cells or compartments and provide
internally within each insert a multiplicity of liquid passages and
liquid obstructions. Hence each compartment has a self-contained
hydraulic energy absorbing system which functions both
independently of the like systems in adjacent cells and in
cooperation with the like systems in adjacent cells. The surge
mitigators throttle fluid flow within a cell and between cells and
prevent rapid, and complete hydraulic fluid evacuation from any of
the compartments as a result of impact. The foam inserts also act
as pumps to restore hydraulic fluid to a cell after compressive
force thereon has been released.
In a preferred embodiment, reticulated open-celled polyurethane
foam inserts provide a throttling action to hydraulic fluid flow
within the compartments. This throttling action causes a fluid
pressure drop and consequent substantial energy absorption within
the individual compartments as well as absorption of energy as the
fluid is squeezed through the small passageways interconnecting the
compartments. Inasmuch as the preferred arrangement includes surge
mitigators in each of the fluid compartments, and the surge
mitigators substantially occupy the included space within the
undeformed fluid compartments, the porous inserts in adjacent
compartments obstruct flow of fluid through the passageways into
the adjacent compartments.
In addition, the porous inserts or surge mitigators damp liquid
flow noise of sloshing within the compartments during use and
retain sufficient liquid in a compartment even when the
compartments are substantially deformed to prevent complete
collapse or bottoming of a compartment and thus loss of energy
absorbing capability which can occur in prior art hydraulic
liners.
Further objects, advantages and features of the invention will
become apparent from the following disclosure.
DRAWINGS
FIG. 1 is an exploded view of a football helmet shell with an
intermediate sizing liner and a multi-compartment hydraulic liner
or suspension with surge mitigators in the liner compartments, in
accordance with the invention.
FIG. 2 is a developed plan view of the hydraulic liner shown in
FIG. 1.
FIG. 3 is an enlarged fragmentary sectional view of an assembly of
the parts shown in FIG. 1.
FIG. 4 is an enlarged fragmentary perspective view of a portion of
the hydraulic liner shown in FIGS. 1, 2 and 3 showing the hydraulic
fluid inlet valve.
FIG. 5 is an enlarged sectional view along line 5--5 of FIG. 2.
FIG. 6 is a perspective view of a surge mitigator.
Although the disclosure hereof is detailed and exact to enable
those skilled in the art to practice the invention, the physical
embodiments herein disclosed merely exemplify the invention which
may be embodied in other specific structure. The scope of the
invention is defined in the claims appended hereto.
The protective gear of the invention can be employed in all types
of protective gear and especially head gear for sports, industry,
military, etc. For exemplification, the invention is illustrated as
embodied in a football helmet 10 which includes a one-piece molded
helmet shell 12 (FIG. 1) made of an impact resistant plastic such
as Cycolac, a sizing liner 16 and a hydraulic liner or suspension
50 provided with hydraulic fluid compartments containing foam
inserts or surge mitigators 89. When properly fitted with sizing
liners 16, all portions of the inside surface of the helmet are
desirably at the same approximate distance from the skull to
dispense shock loads.
The sizing liner 16 is desirably made of a firm but resilient
plastic foam such as Ensolite to provide additional protection.
Sizing liners of various thicknesses are utilized to achieve proper
fitting of the helmet for each user. The helmet shell can also be
constructed in various standard head sizes. The sizing liners 16
have four radially projecting segments 18, 20, 22 and 24 (FIG. 1)
which diverge or increase in area radially outwardly from a central
hub portion 26. When assembled in the helmet shell 12, the adjacent
edges of the segments 21, 23 abut to thus provide substantially
complete coverage of the inside surface area of the helmet and the
area of the helmet covering the wearer's head. The sizing liner 16
is detachably secured to the inside surface of the helmet with
front and rear soft vinyl snubbers 28 and 30 (FIG. 3) which have a
hooked or U-shaped terminal extremity 32 which receives the margin
27 of the liner 16 and securely engages the lower margin 34 of the
helmet. Tabs 31 on vinyl snubbers 28, 30 are glued or otherwise
attached to the liner 16. Mating tape tabs such as Velcro tabs 33
can also be employed to connect with complementary tabs adhered to
the inside surface of the helmet shell 12.
The liner 16 is also provided with a plurality of tape tabs 42
arranged around the radially extending segments 18, 20, 22, 24 for
detachable engagement with mating tape tabs 44 on the hydraulic
liner when the hydraulic liner 50 is assembled in the helmet shell
12. Tape tabs 42, 44 are desirably formed of complementary Velcro
fastener elements.
The exemplified hydraulic liner or suspension 50 of the invention
includes an assembly of four radially extending multi-compartment
segments 60, 62, 64 and 66 (FIG. 2) with each of the segments
including three compartments 68, 70 and 72. The multi-compartment
segments diverge or increase in area radially outwardly from a
central or crown compartment 73 and are complementary to the shape
of the segments 18, 20, 22, 24 of the sizing liner. The segment 62
which spans the inside of the rear 75 of the helmet shell 12 is
desirably larger in size than the other segments, thus to cover the
larger rear helmet area. The individual compartments in each
segment are arranged around central openings 76 and are
interconnected by fluid passages 78. The compartments 72 adjacent
the central or crown compartment 73 are interconnected with the
central compartment 73 by fluid passages 82.
The compartments in the liner 50 are desirably vacuum formed from
one sheet of tough vinyl plastic 71 laminated to a flat backing
sheet 81 of like tough vinyl plastic (FIG. 5) by heat sealed seams
79 around the compartments and passageways 78. The crown
compartment 73 is provided with a vinyl valve assembly 83 (FIG. 4)
for introduction of a hydraulic fluid. The valve assembly 83 is
heat sealed to the wall 84 of the compartment 83 and includes a
valve member or plug 85 having an annular groove 86 which snaps
into the internal shoulder 87 in the fill tube 99 to seal the crown
compartment 73 when the valve plug and tube 99 are pressed
together. This valve is self-closing under pressure from within
compartment 73. A pull tab 91 facilitates separation of the plug 85
from the shoulder 87 to open the valve. The wall 84 which carries
the valve 83 is located against the sizing liner 16 when the liner
16 and the liner 50 are assembled in the helmet to prevent
accidental opening of the valve without disassembly of the liners.
When the valve 83 is closed, the entire valve assembly except for
the tab 91 are recessed beneath the surface 84.
A hydraulic fluid with a low freezing temperature such as a mixture
of Propylene Glycol and water is contained in the compartments. The
viscosity of this fluid is not substantially different from that of
water. In a practical embodiment when sixteen fluid ounces of
liquid are utilized in the suspension, this quantity consists of
eight fluid ounces each of water and Propylene Glycol, the same
being completely miscible.
In accordance with the invention, each of the hydraulic fluid
compartments in the hydraulic liner 50 is provided with hydraulic
fluid surge mitigating and hydraulic fluid and energy absorbing
means for retaining the hydraulic fluid and for impeding and
throttling hydraulic fluid flow within the compartments and between
compartments, thus to dissipate energy caused by an impact on the
helmet and deformation or compression of one or more compartments.
In the disclosed construction, the hydraulic fluid surge mitigating
means comprises reticulated open-celled foam inserts 89 which as
shown in FIGS. 2 and 6 have a configuration complementary to the
configuration of the cell and substantially completely occupy the
volume of the interiors of the compartments. The open-celled
reticulated polyurethane foam described in Volz U.S. Pat. No.
3,171,820 and marketed as Scott Industrial Foam has been
successfully utilized. This foam is available in various specified
porosities or pores per linear inch. Other desirable
characteristics of this foam include flexibility, compressibility,
light weight and high fluid permeability with uniform porosity. An
insert porosity of 80 pores per linear inch has provided the
desired regulated flow characteristics.
The surge mitigators or foam inserts 89 internally provide a
multiplicity of fluid passages and fluid obstructions which
throttle hydraulic fluid flow within the cell to cause a pressure
drop resulting in energy absorption or dissipation within
compartments. The foam inserts also prevent complete evacuation or
loss of hydraulic fluid from a particular compartment and thus
prevent bottoming out or complete collapse of the compartment or
cell and thus loss of energy absorbing capability which can occur
with prior art hydraulic liners. Moreover, the foam inserts prevent
sloshing of hydraulic fluid within the compartments and the
disturbing noise associated with the sloshing of hydraulic
fluid.
The hydraulic fluid retaining characteristics of the foam inserts
are such that even if a compartment ruptures, the hydraulic fluid
loss from the ruptured compartment is minimal.
In addition to providing for primary absorption or dissipation of
energy within the compartments, the passageways 78 and 82 provide
obstructions to hydraulic fluid flow between the compartments for a
secondary energy absorption stage. The hydraulic fluid surge
mitigators in adjacent compartments also obstruct flow between the
compartments. For instance, if the compartment 70 (FIG. 5) is
compressed and hydraulic fluid is squeezed through the passageway
78 in the direction of arrow 97, the surge mitigator 89 in
compartment 68 will obstruct flow at 92 of hydraulic fluid moving
through passageway 78.
The preferred foam has a density of about 0.2 lbs./cu. ft. Hence it
is very light in weight. The pores are so numerous that the
skeletal structure of the strand material of the foam occupies only
about 3 percent of the foam volume, thus leaving about 97 percent
of void space available for fluid retention. The absorptive
capacity of the foam is so great that even if a chamber is
ruptured, there will only be a loss of five percent or less of the
hydraulic fluid, the balance remaining absorbed in the foam
insert.
Utilization of the foam inserts makes it possible to reduce the
amount of liquid in the suspension without loss of energy
absorptive capability. This reduces the weight of the suspension
below what would be required in the absence of the surge mitigators
and reduces fatigue and annoyance otherwise experienced by the
wearer.
The fluid suspension of the present invention contains air,
hydraulic fluid and the foam surge mitigators. In a practical
embodiment of the invention, the percentage mixture for a football
helmet suspension containing sixteen fluid ounces of hydraulic
fluid is as follows:
Hydraulic fluid 65% Air 30% Foam insert (less void space) 5%
In the football helmet suspension above mentioned, measured volumes
were as follows:
Total internal volume of hydraulic cell envelopes 724.4 milliliters
Total volume of hydraulic fluid within the envelope 473.16
milliliters Total volume of air within the envelope 216.4
milliliters Total volume of foam insert (excluding void space)
34.84 milliliters
Accordingly, the hydraulic fluid is a major component of the
ingredients in said embodiment and occupies in excess of one-half
of the total available space.
This mixture has proven highly satisfactory but may not be optimum.
Variations from the foregoing percentages will also be useful.
Reductions of the percentage of hydraulic fluid from the indicated
amount will reduce the quantity of hydraulic fluid which can react
to impact and move from one pressure zone to another and hence will
reduce pro rata the cushioning and energy absorbing capacity of the
system. Increase of the percentage of hydraulic fluid from the
indicated amount will reduce the void or free space within the
suspension and hence will slow the rate of migration of the fluid
within any one compartment and from one compartment to another,
thus also reducing pro rata the cushioning and energy absorbing
capacity of the system. Accordingly, the foregoing mixture
percentages are given as an example only, as other mixture
percentages will likewise have beneficial results. A universal
optimum percentage mix has not been established, as this will vary
according to helmet size and the particular use to which the helmet
or other gear is to be put. It is believed, however, that the
percentage mixture above stated is nearly optimum for a standard
football helmet.
Certain aspects of the particular shape and configuration of the
hydraulic suspension 50, as illustrated in FIG. 2, are also
believed to be advantageous. Each segment 60, 62, 64, 66 has but a
single channel 82 connecting it to the control compartment 73.
Accordingly, flow of hydraulic fluid out of any such segment and
migration of fluid to the control compartment and thence to other
segments is restricted.
Gravity will tend to cause the hydraulic fluid to drop to the
bottom of the respective compartments. The effects of gravity are
counteracted by the absorptive capacity of the surge mitigators 89
which hold the fluid in suspension within the compartments against
the force of gravity.
Accordingly, the surge mitigators tend to stabilize the hydraulic
fluid in approximately equal amounts in each compartment where it
is instantly available for impact and shock absorption, regardless
of the altitude of the helmet or position of the wearer. Moreover,
the foam inserts act as pumps to restore hydraulic liquid to a cell
from which the liquid may have been squeezed, as the foam inserts
resiliently expand.
The channels 82, 78 are formed adjacent wall 81 (FIG. 5) of the
suspension. Accordingly, when the suspension is oriented in the
helmet with wall 81 uppermost, as shown in FIG. 3, the channels 82,
78 will be uppermost, thus trapping hydraulic fluid in sump
portions of the compartments therebelow. This arrangement also
restricts transfer of liquid from one chamber to another and helps
stabilize an even distribution of the liquid throughout the
suspension.
While the invention is primarily intended for use with head gear,
it is also applicable to other protective gear such as shoulder
pads, shin guards, knee pads, etc.
* * * * *