U.S. patent number 3,674,115 [Application Number 05/074,736] was granted by the patent office on 1972-07-04 for liquid shock absorbing buffer.
This patent grant is currently assigned to Energy Absorption Systems, Inc.. Invention is credited to Duane B. Ford, Wan Seegmiller, Grant W. Walker, Bruce O. Young.
United States Patent |
3,674,115 |
Young , et al. |
July 4, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
LIQUID SHOCK ABSORBING BUFFER
Abstract
A reuseable impact attenuation construction designed to protect
fixed objects near highways or vehicular traffic routes from damage
due to high velocity impact. The invention comprises a plurality of
collapsible, incompressible fluid filled energy absorbing and
dissipating buffer elements separated by collapsible panel and
diaphragm means whereby the force of impact of a colliding vehicle
compresses the aforesaid structure, causing a pressure build-up in
the fluid filled buffer elements which are sandwiched between the
panel and diaphragm means. The energy of impact is dissipated in
said buffer elements by the controlled escape of fluid therefrom
through a series of sharp edged orifices. The internal pressure in
the buffer elements creates a resisting force which dissipates the
kinetic energy of the impacting vehicle and brings it to a safe,
controlled stop without damage to said fixed object and without
injuring the occupants of the vehicle. BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to constructions
for protecting fixed structures from damage resulting from
colliding vehicles or the like. More particularly, this invention
relates to a reuseable impact attenuation device designed to absorb
and harmlessly dissipate the energy of impact of a colliding
vehicle or the like with a fixed structure along or near a highway,
such as a bridge abutment, parapet, sign or light stanchion or the
like. 2. Description of the Prior Art It is known to put rigid
guard rails and similar immovable protective devices alongside
vehicular traffic routes such as high speed highways for the
purpose of preventing cars, buses, trucks and other vehicles from
colliding with fixed structures such as abutments, columns, and
sign supports, for example, which may be positioned near or
adjacent to such vehicular traffic routes. Common practice is to
place a rigid railing between the vehicular traffic route and the
fixed structure to deflect the automobile in such a manner that the
automobile, or other vehicle, avoids direct impact with the fixed
structure. Such devices are of only limited value since they do not
attempt to decelerate the vehicle at a controlled, safe rate to
provide maximum safety and minimum injury to the occupants of the
impacting vehicle. Further, such devices result in the impacting
vehicle being thrown back on the highway where it may collide with
other moving vehicles. The present invention utilizes, in part,
devices for absorbing or dissipating the kinetic energy of a moving
body which are described in the patent application of John W. Rich,
Ser. No. 664,333, filed Aug. 30, 1967, now U.S. Pat. No. 3,503,600
and titled "Liquid Filled Buffer for Absorbing Kinetic Energy." A
portion of the individual buffer members described in said
application, or buffer members somewhat similar thereto, form part
of the construction of this invention. Further, this invention is
an improvement over the device disclosed in the patent application
of Grant W. Walker and Duane B. Ford, Ser. No. 48,950, filed June
22, 1970 and which is a continuation of application Ser. No.
777,329, filed Nov. 20, 1968, titled "Diaphragm Buffer Protective
Construction" now abandoned. SUMMARY OF THE INVENTION It has been
discovered that an improved energy absorbing and dissipating device
for protecting stationary structures from damage due to impacting
vehicles, while safely bringing the vehicle to a
controlled-deceleration stop, can be provided utilizing clusters of
energy absorbing buffer members or cells arranged in chambers which
sandwich or telescope into each other upon impact, whereby said
chambers are partly formed by lateral extending fender panels which
aid in properly re-directing the car after lateral impact on the
side of the protective device. Accordingly, it is a principal
object of this invention to provide a novel construction for
protecting a stationary structure which includes at least a cluster
of energy absorbing and dissipating buffer elements each arranged
in a plurality of chambers defined by diaphragms and laterally
extending fender panels such that an edge of each fender panel
overlaps one of said diaphragms permitting said chambers to
collapsibly telescope into one another upon impact of a vehicle
with the protective construction whereby the energy of impact is
absorbed and dissipated by the buffer members and the mass of the
construction itself. It has been further discovered that when the
device of the present invention is constructed comprising several
clusters of energy absorbing buffer elements in a plurality of
chambers spacially disposed throughout the extent of said device, a
controlled dispersion of an impact shock wave created in said
device can be obtained by reducing the capability of the device to
directly transmit the shock wave therethrough. Accordingly, it is
an important object of one embodiment of the present invention to
provide at least a single chamber void of buffer elements, whereby
direct transmission of the impact shock wave is interrupted and
partially dispersed by said void chamber. It has further been
discovered that in a device such as disclosed herein with at least
a void chamber, additional shock absorbing means can be provided in
the portion of the device between said void chamber and the
protected stationary structure to absorb and dissipate the effect
of the remaining impact shock wave passing beyond the void chamber.
Therefore, it is still another object of this invention to provide
an energy absorbing and dissipating device to protect a stationary
structure comprising clusters of buffer elements arranged in
spacially disposed chambers defined in part by diaphragms wherein
maximum impact shock wave attenuation is achieved by leaving one
chamber void of buffer elements and increasing the mass of at least
one of the diaphragms between the void chamber and the stationary
structure. An additional object of the invention is to provide
greater control in positioning the resisting mass of the unit and
in diminishing its effect upon the vehicle during deceleration.
Still another object of the present invention is to provide an
improved impact attenuation device which produces a satisfactory
deceleration wave upon impact. A further object of the present
invention is to provide an impact attenuation device comprising
laterally disposed fender panels to effectively deflect an
impacting vehicle away from a protected stationary structure at a
low angle relative to the normal direction of vehicle travel. An
additional object of the present invention is to provide an impact
attenuation device comprising restraining and pull-out cable means
attached to various members thereof which resist deformation of
such device when impacted laterally by a colliding vehicle. The
novel construction illustrated in the drawings and described
hereinafter constitutes more specific objects of the invention, but
the invention is not deemed to be limited to the exact construction
illustrated.
Inventors: |
Young; Bruce O. (Sacramento,
CA), Walker; Grant W. (Sacramento, CA), Ford; Duane
B. (Placerville, CA), Seegmiller; Wan (El Dorado,
CA) |
Assignee: |
Energy Absorption Systems, Inc.
(Chicago, IL)
|
Family
ID: |
22121373 |
Appl.
No.: |
05/074,736 |
Filed: |
September 23, 1970 |
Current U.S.
Class: |
404/6; 104/256;
188/32; 256/13.1; 267/139; 293/102; 405/212; 104/254; 114/219;
256/1; 267/116; 293/1; 293/107 |
Current CPC
Class: |
F16F
15/023 (20130101); E01F 15/146 (20130101) |
Current International
Class: |
E01F
15/00 (20060101); E01F 15/14 (20060101); F16F
15/023 (20060101); E02b 003/22 (); F16f 005/00 ();
F16f 009/08 () |
Field of
Search: |
;61/46,48
;104/249,254,256 ;114/219 ;188/1B,1C,32,129,266,298 ;256/1,13.1
;267/116,139 ;293/1,70,71R,71P,60,64 ;9/8 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: La Point; Arthur L.
Assistant Examiner: Beltran; Howard
Claims
We claim:
1. An impacting absorbing safety buffer device for a fixed
structure comprising:
a rigid backing member adapted to be positioned adjacent said fixed
structure;
collapsible, energy absorbing and dissipating means comprising a
plurality of individual elements positioned in an ordered array
extending forwardly of said backing member;
diaphragm means comprising a plurality of individual diaphragm
members interposed in said array at spaced intervals and with the
opposed ends of at least preselected ones of said diaphragm members
extending laterally outward of said array of individual
elements;
fender means comprising panel members pivotally coupled to the
opposed ends of said selected diaphragm members, said panel members
extending rearwardly from their associated diaphragm member and
partially overlapping the panel members associated with the
succeeding diaphragm member; and
non-rigid means interconnecting said backing member and said
diaphragm means.
2. The impact absorbing safety buffer device of claim 1
wherein:
said diaphragm means and said fender means are constructed to
telescope into each other upon impact;
and said panel members of said fender means are normally biased
into engagement with the panel members of the succeeding diaphragm
member.
3. The impact absorbing safety buffer device of claim 1
wherein:
said individual elements of said energy absorbing and dissipating
means are arrayed in a series of adjacent rows between at least
preselected ones of said diaphragm panels; and
said diaphragm means further includes interior panels interposed
between adjacent rows of said individual elements.
4. The impact absorbing safety buffer device of claim 3
wherein:
said individual elements of said energy absorbing and dissipating
means each comprise a fluid filled cavity, and orifice means
positioned above said cavity to permit discharge of said fluid from
said fluid filled cavity through said orifice means only at a rate
commensurate with an impact force applied thereto.
5. The impact absorbing safety buffer device of claim 1
including:
additional collapsible energy absorbing and dissipating means
located in front of the forward most diaphragm member.
6. The impact absorbing safety buffer device of claim 1
wherein:
said non-rigid means includes a restraining cable structure rigidly
anchored at one end in advance of the forwardmost one of said
diaphragm members and at its opposite end to said rigid backing
member and passing through apertures in said diaphragm means to
guide and control the movement of said diaphragm means during
impact.
7. The impact absorbing safety buffer device of claim 6
wherein:
said restraining cable means comprises at least two laterally
spaced cables which diverge from each other from the front to the
rear of said device to compensate for any slack that may develop
due to position changes of said diaphragm means.
8. The impact absorbing safety buffer device of claim 6
wherein:
said non-rigid means further includes a pull-out cable structure
attached to said diaphragm means to prevent said diaphragm means
from moving in a direction to enlarge said chamber means, said
non-rigid means constituting the substantially exclusive means for
interconnecting said diaphragm means.
9. The impact absorbing safety buffer device of claim 7
wherein:
each succeeding diaphragm member is laterally wider than the
preceding diaphragm member disposed toward said backing member, and
said diaphragm members and said clusters of energy absorbing and
dissipating means are positioned to form a generally
frustro-conical configuration.
10. An impact absorbing safety buffer device for a fixed structure
comprising:
a rigid backing member adapted to be secured adjacent said fixed
structure;
a plurality of spaced, substantially vertically disposed diaphragm
members with laterally disposed fender members pivotally attached
to two vertical sides of said diaphragm members;
said diaphragm members being positioned in spaced relation to one
another and with said fender members associated with each diaphragm
member partially overlapping respective fender members associated
with a successive diaphragm member for forming a plurality of
chambers spacially disposed in front of said backing member when
said fender means are in a longitudinally extensive position;
energy absorbing and dissipating means disposed in said chambers;
and
means for interconnecting and partially restraining movement of
said diaphragm means consisting essentially of flexible cables.
11. The impact absorbing safety buffer device of claim 10
wherein:
said fender means when disposed in said longitudinally extensive
position forms a barrier means which effectively deflects a vehicle
impacting laterally with said safety buffer device at a
substantially low angle measured along the longitudinal extent of
said safety buffer device.
12. The impact absorbing safety buffer device of claim 10
wherein:
the sides of said fender means facing the direction of impact have
a surface composed of a material having a relatively low
coefficient of friction.
13. The impact absorbing safety buffer device of claim 10
wherein:
said interconnecting and restraining means comprises cables rigidly
anchored at one end at a location in advance of the forwardmost of
said diaphragm members and at its opposite end to said rigid
backing member and passing through apertures in each of said
diaphragm members, for resisting lateral deformation of said safety
buffer device during lateral impact along said fender members.
14. An impact absorbing safety buffer device for a fixed structure
comprising:
a rigid backing member adapted to be secured adjacent said fixed
structure;
a plurality of spaced apart diaphragm members with laterally
disposed fender members attached thereto forming a plurality of
chambers sequentially aligned chambers disposed intermediate
respective adjacent pairs of said diaphragm members and spacially
disposed in front of said backing member; and
collapsible energy absorbing and dissipating means disposed in only
preselected ones and less than all of said plurality of
chambers.
15. The impact absorbing safety buffer device of claim 14
wherein:
said device includes eight chambers and said energy absorbing and
dissipating means is disposed in all but the third chamber from the
front of said device.
16. The impact absorbing safety buffer device of claim 14
wherein:
said energy absorbing and dissipating means includes a cluster of
flexible housing members each comprising a fluid filled cavity
therein and orifice means positioned above said cavity to permit
discharge of said fluid from said fluid filled cavity through said
orifice means only at a rate commensurate with an impact force
applied thereto.
Description
Other objects and advantages of the invention will appear from the
specification which follows with reference to the drawings
wherein:
FIG. 1 is a side elevational view of the cell sandwich impact
attenuation device forming the present invention in place
protecting an abutment;
FIG. 2 is a top plan view of the impact attenuation device of FIG.
1;
FIG. 3 is a top plan view of a modified embodiment of the present
invention wherein one chamber is void of buffer elements;
FIG. 4 is a top plan view of the impact attenuation device of FIG.
1 as it appears after a head-on impact by a moving vehicle or other
object;
FIG. 5 is a top plan view of the impact attenuation device of FIG.
1 as it appears after a side-angle impact by a moving vehicle or
other object;
FIG. 6 is a detail side elevational view of the restraining cable
and backup plate construction, showing the relative location of the
forward diaphragm, interior panels, and slide straps;
FIG. 7 is a detail side elevation view of the secondary cable and
pull-out cable construction of the present invention;
FIG. 8 is a detail view of a typical diaphragm, including fender
panel hinges, pull-out cable clips, and restraining cable eye
guides;
FIG. 9 is a detail view of the front diaphragm;
FIG. 10 is a detail view of a typical interior panel;
FIG. 11 is a detail side elevational view of a preferred manner of
fixing the buffer elements or cells to the structural rings and
interior panels;
FIG. 12 is a plot of acceleration forces on the impacting vehicle
in g's versus time in milliseconds using the impact attenuation
device of FIG. 2;
FIG. 13 is a plot of acceleration forces on the impacting vehicle
in g's versus time in milliseconds using the modified impact
attenuation device of FIG. 3;
FIG. 14 is a detail plan view of a preferred manner of connecting
the fender panels and diaphragms.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is made to FIGS. 1 and 2 for a description of the first
embodiment of the invention.
A fixed structure such as an abutment 10 which is normally located
adjacent or near a route of vehicular travel, such as a street or
highway, is sought to be protected. This protection encompasses one
of the main objects of the invention, along with the protection of
a vehicle and the occupants thereof from injury upon collision of
the vehicle with a fixed structure such as abutment 10.
If the existing concrete or steel stationary structure 10 is not
capable of resisting the imposed forces brought into play by the
impact of a colliding vehicle with the cell sandwich unit, a rigid
backing member 12 is provided to reinforce the stationary
structure. The rigid backing member 12 comprises two cable
fastening means 14 firmly secured to backing member 12. Positioned
in front of and in contact with backing means 12 are a plurality of
clusters 16 of energy absorbing and dissipating buffer members 18
partially filled with an incompressible fluid material which is
preferably water. However, any fluent material which is essentially
incompressible may be used. Buffer members 18 are collapsible
flexible cell cartridges which have the characteristic of remaining
flexible and water tight in extremes of heat and cold. As an
example, and not by way of limitation, buffer members 18 may
comprise a vinyl coated nylon fabric cylindrical body with an open
end and a diameter of approximately 5 1/2 inches. The length may
vary as required by the installation, but lengths of 24, 30 and 36
inches have found to be satisfactory for most installations. The
base fabric of buffer elements 18, by way of example, may consist
of 6.1 ounces of nylon and 16 ounces of vinyl to produce a total
weight of 22 ounces per yard. This provides a material which is
capable of offering a hydrostatic resistance of 300 psi or better.
An insert 20 (FIG. 11) containing sharp-edged orifices 22 to
regulate the rate of release of water from the buffer elements 18
is affixed to the open end of the buffer elements. Upon impact, the
release of water from the elements 18 by turbulent viscous flow is
controlled by orifices 22 which put a limit on the hydraulic
pressure by venting the fluid after buildup to a maximum pressure,
in the manner taught in the application of John W. Rich, Ser. No.
644,333, filed Aug. 30, 1967, titled "Liquid Filled Buffer for
Absorbing Kinetic Energy." As a result, the escape of fluid from
buffer elements 18 occurs only at a rate commensurate with the
impact force applied thereto. The sizes of orifices 22 will be
established pursuant to requirements of speed limits, weights of
vehicles, desired deceleration rate, etc.
The clusters 16 of elements 18 are formed by placing the buffer
elements in lateral rows which are held in a spaced relation by
interior panels 24, which may be composed of overlaid plywood or
any other suitable material. As shown in FIG. 2, an exemplary
cluster towards the rear of the protective device comprises four
rows of elements 18 separated by three interior panels 24. At the
forward end, where the lateral dimensions of the cell sandwich unit
are not as great, each row comprises a lesser number of buffer
elements 18. Elements 18 are secured to the interior panels 24 by
structural rings 26 (FIG. 11) which are attached to the interior
panels by suitable means such as bolts 28. Flexible elements 18 are
held in rings 26 by the force of friction, or the elements 18 may
comprise an upper flanged portion such as keeper ring 27 to prevent
the cells from falling through the structural rings. Since the
buffer elements 18 are not self-supporting, interior panels 24 hold
the cells erect.
Adjacent the outermost row of elements 18 in any cluster 16 is a
movable diaphragm 30 which, along with fender panels 32 pivotally
attached to and extending laterally and rearwardly from two lateral
sides of each diaphragm 30, forms a chamber housing each cluster
16. As shown in FIG. 2, each preceding chamber located from back-up
member 12 is of lesser width than the succeeding chamber. This
construction enhances the ability of the chambers to telescope one
into the other upon impact. Diaphragms 30 may be fabricated, as an
example, from 1 1/2 inch thick laminated wood, coated on both sides
with fiber-glass. Fender panels 32, for example, may be constructed
of any suitable material such as 3/4 to 1 1/4 inch plywood, and are
preferably coated on both sides with fiberglass. It is to be
understood that the thickness of the diaphragms 30 and fender
panels 32 may be varied from these dimensions depending upon the
force of impact against which the invention is designed to protect.
The exterior surface of fender panels 32 is coated with a "floated"
resin material or the like, to reduce the coefficient of friction
for purposes to be explained. Fender panels 32 are held in a
longitudinally extensive, or inward, position by means of springs
33 (FIG. 14). Fender panels 32 are fastened to diaphragms 30 by
means of loose pin hinges 35, thus facilitating the replacement of
damaged fender panels.
Fender panels 32 are pivotally attached to diaphragms 30 by means
of hinges 34 (FIGS. 8, 11). The free swinging end of each fender
panel 32 abuts the pivotal end of the succeeding fender panel in an
overlapping manner, and lies on the outside thereof. It can be seen
that upon compression due to impact of the chambers housing
clusters 16, each fender panel 32 will slide outside of the
succeeding fender panel, causing the chambers of clusters 16 to
telescope into each other. (FIG. 5). The most rearward fender
panels 32 on each side of the protective device abut a buffer
element 36 (FIG. 2), which is similar to that described in the
aforesaid patent application of John W. Rich. If the force of
impact from a head-on collision is great, the force against the
protective structure comprising this invention causes fender panels
32 to pivot outwardly against the force of springs 33 as the
chambers housing clusters 16 are telescoped inwardly, as shown in
FIG. 4.
At the forward, or nose, end of the impact attenuation structure,
immediately adjacent the first diaphragm 30, is a cluster of buffer
elements 38 substantially similar to the buffer elements disclosed
in the aforesaid patent application of John W. Rich. These buffer
elements 38 preferably comprise hollow, vinyl plastic cylinders
substantially filled with an incompressible fluid. An insert
similar to insert 22 shown in FIG. 11, containing sharp-edged
orifices to regulate the release of fluid from the cylinder at a
rate commensurate with the force of compression upon impact, is
secured to an open end of the cylinders. The material comprising
buffer elements 38 shall be chosen to possess high strength while
retaining flexibility at both high and low temperatures.
A series of cables are provided to assist in supporting the impact
attenuation device of the present invention, and to further enhance
the impact absorbing and dissipating capabilities of the structure.
Two restraining cables 40 are securely fastened at a point beyond
the forward end of the cell sandwich unit to a fixed cable
anchorage 42, and pass through reinforced apertures 44 in movable
diaphragms 30 (FIGS. 6, 8). As shown in FIGS. 6 and 9, apertures 44
in the forward two diaphragms 30 are nearer the ground since
restraining cables 40 pass through the two forward diaphragms 30 as
they are rising from cable anchorage 42. Restraining cables 40 also
pass along the lateral edge of each interior panel 24, which
comprise a reinforced portion 47 (FIG. 10) which contacts the
restraining cables 40 and protects the interior panels from
excessive wear.
Restraining cables 40 rise from cable anchorage 42 in a vertical
plane to the third diaphragm 30 counting from and including the
forward diaphragm, passing through apertures 44 in all diaphragms
through which the restraining cables pass. From the third
diaphragm, restraining cables 40 pass through apertures 44 of the
remaining diaphragms, and are ultimately firmly anchored to cable
fastening means 14. In the horizontal plane, as seen in FIG. 2,
restraining cables 40 extend inwardly from cable anchor 42 to the
forward diaphragm 30, from where they flare outwardly to fastening
means 14. This flared traverse of restraining cables 40 assists in
maintaining the cell sandwich unit in place during lateral
impacts.
As shown in FIG. 7, a secondary set of cables 46 are provided,
which are fastened at one end to cable anchor 42 by means of shear
pins 48, which break upon impact. The opposite ends of secondary
cables 46 are firmly attached to the forward diaphragm 30.
Turnbuckles 49 are provided to maintain secondary cables in a taut
condition. Upon impact, shear pins 48 break as forward diaphragm 30
is forced back in the direction of abutment 10. (FIGS. 4, 5).
In addition to the aforementioned restraining and secondary cables,
two pullout cables 50 are attached to the corners of each diaphragm
30. (FIGS. 1, 7). For this purpose, cable clamps 52 are provided at
the four corners of each diaphragm to which pullout cables 50 are
attached. Pullout cables 50 act during a lateral impact to provide
an internal compressive force which acts on the buffer elements 18,
to which the energy of impact is ultimately transferred for
absorption and dissipation. Further, the unit may be substantially
returned to its original shape after an impact by applying a
tension force to pullout cables 50. Turnbuckles 49 also assist in
keeping the pullout cables 50 in a taut condition.
Slide straps 54 are provided on the ground along the length of the
cell sandwich unit beneath diaphragms 30. Upon impact, the
diaphragms are readily movable along slide straps 54.
The embodiment of the invention disclosed in FIG. 3 differs from
the embodiment of FIGS. 1, 2, 4 and 5 in that the third chamber
counting from the forward, or nose end is void of buffer elements
18. It has been discovered that by leaving a void chamber, a
modified shock wave pattern is produced in the transmittal of the
impact wave to the back-up plate 12. This is diagrammatically
illustrated in FIGS. 12 and 13. FIG. 12, which was charted using
the device of FIGS. 1 and 2, shows, in a plot of the acceleration
(g) forces on the impacting vehicle versus time (milliseconds) how
an initial shock wave and then a secondary shock wave of slightly
higher amplitude are produced prior to a reduction of the forces on
the vehicle to zero. FIG. 13 shows a plot of the same acceleration
forces versus time developed using a device constructed in
accordance with the embodiment of FIG. 3, with the third chamber
void of buffer elements. The shock wave produced in an equivalent
time period comprises an additional "hump," however, the average
amplitude of the impact force is less than that produced in the
structure of FIGS. 1 and 2. Therefore, while the embodiment of
FIGS. 1 and 2 will be sufficient for most applications, additional
attenuation of the overall shock wave may be produced using a void
chamber such as disclosed in the embodiment of FIG. 3.
In the embodiment of FIG. 3, the shock wave in the device picks up
again when it passes the void chamber. By adding mass to the device
of FIG. 3 by the use of thicker and heavier diaphragms 30 and/or
interior panels 24 between the void chamber and the back-up plate
12, these thickened units will act as shock absorbers without
transmitting the shock wave to the back-up plate.
OPERATION
A vehicle impacting the cell sandwich unit head-on first contacts
the buffer elements 38 located ahead of the nose portion of the
device. Since cable anchorage 42 is almost level with the ground,
the vehicle rides over the anchorage without being impeded thereby.
A portion of the impact energy of the moving vehicle is absorbed
and dissipated by the regulated flow of fluid in buffer elements 38
through the sharp-edged orifices located at one end of each buffer
element.
As the vehicle continues its impacting movement, nose cluster 38 is
forced rearward, and the remaining impact energy is transferred to
forward diaphragm 30 which moves on slide straps 54 and compresses
the buffer elements 18 in the chamber directly behind the forward
diaphragm. A further portion of the energy of impact is absorbed
and dissipated by buffer elements 18 as fluid in said elements is
discharged through orifices 22 (FIG. 11) at a rate commensurate
with the impact force applied thereto. Diaphragms 30 and interior
panels 24 act to uniformly distribute the force of impact amongst a
series of buffer elements in a single row in each of the
chambers.
As buffer elements 18 are compressed in the first chamber, a force
is applied to the succeeding diaphragm 30, which moves along slide
straps 54 and applies a compressive force to the next cluster 16 of
buffer elements 18. The energy absorbtion and dissipating process
described above is repeated by each cluster of buffer elements 18,
with any remaining force of impact being transmitted to the
succeeding adjacent diaphragm 30. This succession of diaphragm
movements and buffer element energy dissipation continues until the
kinetic energy of the vehicle has been completely dissipated, and
the vehicle brought to a safe stop. The heavier the vehicle and the
faster it is going, the further along the length of the cell
sandwich unit it will travel before reaching zero velocity.
Therefore, the energy of impact is dissipated as the walls of
buffer members 38 are collapsed initially by the impact of the
vehicle upon the nose cluster, and by the subsequent movement of
the respective diaphragms and interior panels forcing the collapse
of successive clusters of buffer members 18 positioned between the
diaphragms 30, interior panels 24 and backing plate 12.
Since each diaphragm is successively wider than the preceding one,
a stepped or telescope effect is provided. The larger mass of the
elements of the cell sandwich unit nearer the back-up plate 14
gives the rear portion of the unit a higher degree of shock or
energy absorbing capability. Therefore, as the vehicle moves toward
back-up plate 14, the resistive forces acting to bring it to a halt
increase.
As best shown in FIG. 4, a head-on impact force will cause fender
panels 32 to swing outwardly on hinges 34 due to the movement of
the diaphragms 30 towards each other and the inertia of the fender
panels themselves. The outward movement of these fender panels
requires the expenditure of energy, which is obtained from the
kinetic energy of the impacting vehicle, thereby assisting the unit
further in dissipating the energy of impact.
As diaphragms 30 move towards each other while compressing buffer
elements 18 during impact, restraining cables 40 guide and control
the movement of the diaphragms. The outward flare in the
restraining cables 40 compensates for any slack that may develop
due to geometric position changes of the diaphragms, maintains
tension, and aids in redirecting the car at a low angle during a
side impact. Cables 40 also prevent the cell sandwich unit from
buckling in the lateral and vertical directions.
The secondary cables 46, which are used primarily to maintain the
forward diaphragm 30 in an upright position while the cell sandwich
unit is in place (FIG. 7), are broken loose from cable anchorage 42
upon impact. The tension in secondary cables 46 causes shear pins
48 to break, thereby permitting forward diaphragm 30 to move along
slide straps 54 as previously described.
The cell sandwich unit also works extremely well on side angle
impact, as diagrammatically illustrated in FIG. 5. Due to the force
exerted by the impacting vehicle, fender panels 32 remain in an
inwardly position and act as fenders to deflect the vehicle away
from the unit. This deflection, however, does not direct the
vehicle back to the lane of oncoming traffic. Tests have shown that
a vehicle travelling at 55-60 mph and side-impacting the cell
sandwich unit at an angle of 15.degree. was effectively fendered
away at an angle of ejection within two degrees of being parallel
to the side face of the unit. Thus, the vehicle safely comes to a
stop near the cell sandwich unit, which is located along side the
main traffic route, and not in the lane of moving traffic.
Two factors are primarily responsible for enhancing the effectivity
of the unit during side impacts. First, the two pretensioned
restraining cables 40 are positioned high for stability and near
the center of mass of the unit and of the impacting vehicle. Cables
40 resist extensive lateral movement, yet yield sufficiently to
reduce the force of impact reacting against the vehicle. When the
cell sandwich unit is impacted by a heavy vehicle, such as a loaded
truck or the like, or at high velocity and steep angle, the shear
pin anchoring the cable 40 nearest the impact wall break, releasing
that cable as shown in FIG. 5. However, the remaining cable is
sufficient to resist lateral movement of the unit and aids in
halting the vehicle.
The second factor enhancing the effectiveness of the cell sandwich
unit during a side impact is the low coefficient of friction of the
outer surface of the fender panels 32. This enables the vehicles to
slide more easily along fender panels 32 following impact. Since
the amount of penetration of the vehicle into the unit is small,
and since there is only a small frictional force developed between
the vehicle and the panels, the vehicle is gently redirected and
does not pocket and spin out.
Further resistance to deformation during side angle impacts is
afforded by pull-out cables 50 which are firmly attached to each
diaphragm 30, and prevent movement of said diaphragms in a
direction away from each other, thereby maintaining pressure on
buffer elements 18 during impact.
Generally summarizing the operation of the cell sandwich unit, when
the unit is impacted head on, it compresses, causing a pressure
build-up in the buffer elements 18 which are sandwiched between
diaphragms 30 and interior panels 24. The internal cell pressure
multiplied by its area of contact with the interior panels and
diaphragms equals a resisting force. This resisting force
multiplied by the distance through which the unit acts is a measure
of the energy dissipation during impact. The mass-inertia
phenomenon renders the cell sandwich unit self-adjusting as a
higher mass vehicle automatically produces a higher hydraulic
pressure to absorb impact.
The energy absorption system of the present invention functions to
dissipate the energy of impact in several ways. First, the transfer
of momentum involved in moving the fluid in the buffer elements
through the orifices and into the atmosphere requires the
expenditure of energy. Second, there is created in the buffer
elements 18 a force opposed to the build-up of hydraulic pressure
which eventually yields, but nevertheless, opposes impact prior to
yielding. Also, the shock wave generation through the fluid in the
buffer elements increases the temperature of the fluid, which
further absorbs energy. Further, the mass of the impacting vehicle
and the mass of the structural parts of the cell sandwich unit,
such as diaphragms, cell units, interior panels, cables, etc.,
absorb part of the force of impact. The vinyl housing comprising
the buffer elements also expands during impact, and this expansion
additionally absorbs part of the energy of impact.
Subsequent to either a head-on or lateral impact, the cell sandwich
unit may be easily repositioned by a vehicle such as a tow truck or
the like pulling against the pull-out cables 50 mounted at the top
and bottom and on each side of the unit.
In areas where snow occurs, covers are provided to prevent an
accumulation of snow and ice. In freezing climates, anti-freeze
solutions may be added to the fluid in the buffer elements 18 and
38.
If desired, architectural designs in varying colors and textures
may be affixed to the outer sides of fender panels 32 to make the
unit more pleasing in appearance.
The embodiments disclosed are exemplary of the type of
configuration which may be used to protect fixed structures near or
adjacent routes of vehicular traffic. However, the device may be
used to protect any object from another moving object, and it will
be apparent to the skilled engineer that the configuration of the
diaphragms, panel and buffer element arrangement will to some
degree be dictated by space requirements or the configuration of
the structure with which it is to be associated. Such adaptations
of configurations are well within the skill of the art and are
within the spirit and scope of the invention as defined in the
following claims.
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